# MERCURY AND AIR TOXIC ELEMENT

IMPACTS OF COAL COMBUSTION

BY-PRODUCT DISPOSAL AND UTILIZATION

Final Report

(for the period January 23, 2003 – December 31, 2006)

AAD Document Control

U.S. Department of Energy National Energy Technology Laboratory PO Box 10940, MS 921-143 Pittsburgh, PA 15236-0940

Cooperative Agreement No. DE-FC26-02NT41727 Performance Monitor: Lynn Brickett

Prepared by:

David J. Hassett

Loreal V. Heebink Debra F. Pflughoeft-Hassett Tera D. Buckley

Erick J. Zacher

Energy & Environmental Research Center University of North Dakota 15 North 23rd Street, Stop 9018

Grand Forks, ND 58202-9018

Mei Xin

Mae Sexauer Gustin

Department of Natural Resources and Environmental Sciences University of Nevada, Reno

1664 North Virginia Street FA 128, Mail Stop 370 Reno, NV 89557

Rob Jung

5192 8th Avenue North Grand Forks, ND 58203

2007-EERC-10-03 October 2007DOE DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United

States Government. Neither the United States G overnment, nor any agency thereof, nor any of their employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not n ecessarily constitute or imply its endorsement, recommendation, or favoring by the United States G overnment or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

This report is available to th e public from the National Techni cal Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springf ield, VA 22161; phone orders accepted at (703) 487-4650.

EERC DISCLAIMER

LEGAL NOTICE This research report was prepared by the Energy & Environmental Research Center (EERC), an agency of the Univ ersity of North Dakota, as an account of work sponsored by the U.S. Department of Energy (DOE), the Electric Power Research Institute (EPRI), and Reliant Energy. Because of the resear ch nature of the work performed, neither the EERC nor any of its employees makes any warranty, express or implied, or assumes any legal liability or responsibil ity for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed or repres ents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, proce ss, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement or recommendation by the EERC.

ACKNOWLEDGMENTS

The authors wish to gratefully acknowledge the guidance, support, and assistance of the DOE National Energy Technology Laboratory Performance Monitor, Lynn Brickett, and the industrial sponsor representatives:

Center for Air Toxic Metals ® – John Pavlish Cinergy – Darlene Radcliffe and R. James Meiers EPRI – Ken Ladwig Great River Energy – Mark St rohfus and Diane Stockdill North Dakota Lignite Research Coun cil – Harvey Ness and Jeff Burgess U.S. Waste Activities Group – James RoewerThe authors also wish to acknowledge EE RC colleague Research Microbiologist John Gallagher (1955–2004), who was instrumental in prep aring the project propos al and in initiating the microbiological work described in this report. The project t eam is honored to have worked with him and to have counted him as a colleague and friend.

The guidance and assistance of several ot her EERC colleagues is also gratefully acknowledged, including Kurt Eylands, Bruce Do ckter, Dennis Laudal, Lucinda Hamre, Mike Holmes, Stan Miller, Carolyn Nyber g, Jeff Thompson, and Chad Wocken.

The authors also wish to thank EERC suppor t staff, including Ka ri Lindemann, Tami Votava, Tobe Larson, Michelle Olderbak, and Shannan Longsdor f for all the assistance in performing and completing this project.MERCURY AND AIR TOXIC ELEMENT IMP ACTS OF COAL COMBUSTION BYPRODUCT DISPOSAL AND UTILIZATION

ABSTRACT

The University of North Dakota Energy & Environmental Research Center (EERC) conducted a multiyear study to evaluate the impact of mercury and other air toxic elements (ATEs) on the management of coal combustion by-p roducts (CCBs). The ATEs evaluated in this project were arsenic, cadmium, chromium, lead, nickel, and selenium. The study included laboratory tasks to develop measurement tech niques for mercury and ATE releases, sample characterization, and release experiments. A fiel d task was also perfor med to measure mercury

releases at a field site.

Samples of fly ash and flue gas desulf urization (FGD) materials were collected preferentially from full-scale co al-fired power plants operati ng both without and with mercury control technologies in place. In some cases, samples from pilot- and bench-scale emission control tests were included in the laboratory studies. Several sets of “paired” baseline and test fly ash and FGD materials collected during full-scal e mercury emission control tests were also included in laboratory evaluations . Samples from mercury emissi on control tests all contained activated carbon (AC) and some also incor porated a sorbent-enhancing agent (EA).

Laboratory release experiments focused on measuring releases of mercury under conditions designed to simulate CCB exposure to water, ambien t-temperature air, elevated temperatures, and microbes in both wet and dry conditions.

Results of laboratory ev aluations indicated that:

• Mercury and sometimes selenium are collec ted with AC used for mercury emission control and, therefore, present at higher c oncentrations than samples collected without mercury emission controls present.

• Mercury is stable on CCBs collected from systems both without and with mercury emission controls present under most conditio ns tested, with the exception of vaporphase releases of mercury expos ed to elevated temperatures.

• The presence of carbon either from added AC or from unburned coal can result in mercury being sorbed onto the CCB when exposed to ambient-temperature air.

The environmental performance of the merc ury captured on AC used as a sorbent for mercury emission control technologies indicated that current CCB mana gement options will continue to be sufficiently protective of th e environment, with the potential exception of exposure to elevated temperatures. The envi ronmental performance of the other ATEs investigated indicated that current manageme nt options will be appropriate to the CCBs produced using AC in mercury emission controls.i TABLE OF CONTENTS

LIST OF FIGURES ................................................................................................................ ....... iv

LIST OF TABLES................................................................................................................. ........ vi

NOMENCLATURE ................................................................................................................... .... x

EXECUTIVE SUMMARY .......................................................................................................... xii

1.0 INTRODUCTION............................................................................................................... .. 1

2.0 BACKGROUND................................................................................................................. .. 3

3.0 OBJECTIVES ................................................................................................................. ...... 5

4.0 EXPERIMENTAL ............................................................................................................... . 6

4.1 Literature Search.......................................................................................................... 6 4.2 Analytical Methods Selection...................................................................................... 6 4.3 Sample Identification and Selection ............................................................................ 6 4.3.1 Sample Prioritization ....................................................................................... 7 4.3.2 Sampling and Storage Procedures ................................................................... 8 4.3.3 Sample Collection.......................................................................................... 10 4.4 Chemical and Physical Characterization ................................................................... 10 4.4.1 Analytical Methods for Characteriz ation and Release Experiments ............. 11 4.5 Laboratory Evaluation of ATE Releases ................................................................... 12 4.5.1 Direct Leaching ............................................................................................. 13 4.5.2 Vapor-Phase Mercury Transport ................................................................... 15 4.5.3 Microbiologically Mediated Leaching and Vapor-Phase Transport ............. 20 4.6 Field Investigations.................................................................................................... 25

4.6.1 Field Task 1 ................................................................................................... 25

4.6.2 Alternate Field Task ...................................................................................... 26 4.7 Data Reduction and Interpretation............................................................................. 27

5.0 RESULTS AND DISCUSSION ......................................................................................... 28

5.1 Literature Search........................................................................................................ 28 5.2 Analytical Methods Selection.................................................................................... 29 5.3 Sample Identification and Selection .......................................................................... 30 5.3.1 Sample Prioritization ..................................................................................... 31 5.3.2 Sample Handling ........................................................................................... 33 5.3.3 Sample Descriptions...................................................................................... 34

Continued . . .ii TABLE OF CONTENTS (continued)

5.4 Chemical and Physical Characterization ................................................................... 36 5.4.1 Total Mercury and ATEs............................................................................... 36 5.4.2 Total Bulk Chemical Composition................................................................ 40

5.4.3 LOI and Moisture Content............................................................................. 41

5.4.4 Carbon Forms ................................................................................................ 47 5.5 Laboratory Evaluation of ATE Releases ................................................................... 48 5.5.1 Direct Leaching ............................................................................................. 48 5.5.2 Vapor-Phase Transport.................................................................................. 62 5.5.3 Microbiologically Mediated Leaching and Vapor-Phase Transport ............. 75 5.6 Field Investigations.................................................................................................... 80

5.6.1 Field Task 1 ................................................................................................... 81

5.6.2 Alternate Field Task ...................................................................................... 87 5.7 Data Reduction and Interpretation............................................................................. 89

6.0 CONCLUSIONS AND RECOMMENDATIONS.............................................................. 90

7.0 REFERENCES................................................................................................................. ... 93

SAMPLE IDENTIFICATION FORM ..........................................................................Appendix A

DRAFT STANDARD METHOD FOR SYNTHETIC GROUNDWATER LEACHING PROCEDURE ..........................................................................................Appendix B

MERCURY INFORMATION CLEARING HOUSE REPORTS..................................Appendix C

LABORATORY METHODS FOR THE EVALUATION OF POTENTIAL

RELEASE OF MERCURY FROM COAL UT ILIZATION BY-PRODUCTS............Appendix D

SAMPLE PRIORITIZATION....................................................................................... Appendix E

SAMPLE IDENTIFICATION NUMBER AND DESCRIPTIONS.............................. Appendix F

TOTAL TRACE ELEMENTAL DATA .......................................................................Appendix G

FGD LIQUOR TOTAL TRACE ELEM ENTAL CONCENTRATION AND pH DATA.......................................................................................................................A ppendix H

TOTAL BULK CHEMICAL COMP OSITION DATA ................................................. Appendix I

MOISTURE CONTENT AND LOI DATA...................................................................Appendix J

Continued . . .iii TABLE OF CONTENTS (continued)

pH DATA.......................................................................................................................A ppendix K

CARBON FORMS DATA ............................................................................................ Appendix L

LEACHATE DATA .....................................................................................................Appendix M

MERCURY AND AIR TOXI C ELEMENT LEACHING FROM COAL COMBUSTION BY-PRODUCTS ................................................................................Appendix N

SUMMARY OF LONG-TERM AMBI ENT-TEMPERATURE RELEASE

DATA ........................................................................................................................... .Appendix O

ELEVATED-TEMPERATURE VAPOR-PHASE MERCURY MEASUREMENT FROM COAL COMBUSTION BY-PRODUCTS ........................................................ Appendix P

ELEVATED-TEMPERATURE MERCURY RELEASE DATA.................................Appendix Q

MICROBIOLOGICALLY MEDIATED ME RCURY AND AIR TOXIC ELEMENT

RERELEASES FROM COAL COMBUS TION BY-PRODUCTS ..............................Appendix R

MICROBIOLOGICALLY MEDIATED LEACHING AND VAPOR-PHASE TRANSPORT TASK SAMPLE SET............................................................................ Appendix S

FIELD INVESTIGATIONS TASK SAMPLE SET AND FUNDAMENTAL CHARACTERIZATION DATA................................................................................... Appendix T

ALTERNATE FIELD TASK DATA ............................................................................Appendix Uiv LIST OF FIGURES

2-1 EPA information on mercury emissions ............................................................................... 4

4-1 Categorization of trace elements associ ated with coal ash based on volatility..................... 7

4-2 Mercury distribution in a power plant................................................................................... 9

4-3 Example LTL results for boron........................................................................................... 14

4-4 Indirect evidence of ettringite formation using SGLP and LTL ......................................... 15

4-5 Ambient-temperature mercury vapor release collection apparatus..................................... 17

4-6 Mercury thermal desorption apparatus................................................................................ 18

4-7 Typical thermal desorption curve for fly ash ...................................................................... 19

4-8 Example of thermal desorpti on curve for an FGD material................................................ 19

4-9 Early microbiologically mediated merc ury vapor-phase collection apparatus utilizing a wrist action shak er to facilitate mixing .............................................................. 21

4-10 Microbiologically mediated mercur y vapor-phase collection apparatus utilizing a stir plate to facilitate mixing .............................................................................. 22

4-11 Field sampling site map................................................................................................... .... 27

4-12 CCB–soil mercury vapor rele ase collection apparatus ....................................................... 28

5-1 Fly ash 18-hour SGLP leachate mercury plotted against total mercury content................. 52

5-2 Fly ash + AC and/or EA 18-hour SGLP leachate mercury plotted against total
mercury content............................................................................................................... .... 52

5-3 Arsenic 18-hour SGLP and 30- and 60-day LTL leaching data for a paired sample set .... 56

5-4 Sample Set 1 (194-day) long-term am bient-temperature mercury release or sorption as related to blank values ...................................................................................... 66

5-5 Sample Set 2 (188-day) long-term am bient-temperature mercury release or sorption as related to blank values ...................................................................................... 66

Continued . . .v LIST OF FIGURES (continued)

5-6 Sample Set 3 (187-day) long-term am bient-temperature mercury release or sorption as related to blank values ...................................................................................... 67

5-7 Long-term ambient-temperatur e mercury release rate from Samples 04-082 and 04-083................................................................................................ 70

5-8 Typical two-peak mercury desorption curve for fly ash ..................................................... 74vi LIST OF TABLES

4-1 Microbiological Rereleas e Apparatus Modifications.......................................................... 22

4-2 Microbiological Experime ntal Incubation Conditions........................................................ 24

4-3 Mercury Measurement Site Descriptions............................................................................ 26

5-1 Summary of Fly Ash Samples and Fundamental Characterization Data ............................ 32

5-2 Summary of FGD–SDA Samples and Fundamental Characterization Data....................... 33

5-3 Summary of Eastern B ituminous Wet FGD Material Samples and Fundamental

Characterization Data......................................................................................................... . 33

5-4 Paired Samples and Fundamental Characterization Data.................................................... 34

5-5 Range of Total Trace Elements in Fly Ash Samples .......................................................... 36

5-6 Range of Total Trace Elements in FGD–SDA Samples ..................................................... 37

5-7 Range of Total Trace Elements in Wet FGD Material Samples ......................................... 37

5-8 Total Trace Elements in FGD Gypsum Samples Comparing SCR On and SCR Off......... 38

5-9 Range of Total Trace Elements in FGD Liquor Samples ................................................... 39

5-10 Paired Samples and Total ATE Content ............................................................................. 40

5-11 Summary of Total Bulk Chemical Composition Compared to ASTM C618 Specifications ................................................................................................................ ...... 41

5-12 Range of Moisture Content and LOI in Fly Ash Samples .................................................. 41

5-13 Range of Moisture Content and LOI in FGD–SDA Samples ............................................. 42

5-14 Range of Moisture Content and LOI in FGD Material Solid Samples ............................... 42

5-15 Paired Samples Moisture Content and LOI......................................................................... 43

5-16 Range of pH in Fly Ash Samples ........................................................................................ 44

Continued . . .vii LIST OF TABLES (continued)

5-17 Fly Ash Samples Exhibiting a Greater Than One pH Unit Change over a

24-hour Period................................................................................................................ ..... 45

5-18 Range of pH in FGD–SDA Samples................................................................................... 46

5-19 Ranges of pH in Wet FGD Material Sample....................................................................... 47

5-20 Ranges of pH in Liquid from Wet FGD Material Samples................................................. 47

5-21 Number of Samples per Carbon Form with Total Hg and LOI Ranges.............................. 48

5-22 Ranges of Leachate Results for Fly Ash ............................................................................. 49

5-23 Ranges Leachate Results for FGD–SDA ............................................................................ 49

5-24 Ranges of Leachate Results for Wet FGD Material............................................................ 49

5-25 Ranges of Fly Ash Mercury Leachate Results by Leaching Test ....................................... 50

5-26 Ranges of Fly Ash Mercury Leachate and Leachate pH Results by Coal Type and Leaching Test ............................................................................................................. .. 51

5-27 Paired Samples Mercury 18-hour SGLP and TCLP Leachates and Fundamental

Characterization Data......................................................................................................... . 53

5-28 Paired Mercury Leachates and Fundame ntal Characterization Data of Fly Ash Samples with Enhancing Agent and ACI .................................................................... 53

5-29 Paired Mercury Leachates and Fundame ntal Characterization Data of Fly Ash Samples with AC ......................................................................................................... 54

5-30 Ranges of FGD–SDA Mercury Leac hate Results by Leaching Test .................................. 54

5-31 Paired FGD–SDA mercury leachates a nd fundamental characterization data.................... 54

5-32 Ranges of Wet FGD Material Mercur y Leachate Results by Leaching Test...................... 55

5-33 Range of Fly Ash Arsenic L eachate Results by Leaching Test .......................................... 55

5-34 Ranges of FGD–SDA Arsenic Leach ate Results by Leaching Test ................................... 55

Continued . . .viii LIST OF TABLES (continued)

5-35 Ranges of Wet FGD Material Arseni c Leachate Results by Leaching Test ....................... 56

5-36 Ranges of Fly Ash Cadmium Leachate Results by Leaching Test ..................................... 57

5-37 Ranges of Fly Ash + FGD–SDA Materi al Cadmium Leachate Results by Leaching Test ................................................................................................................. ..... 58

5-38 Ranges of Wet FGD Material Cadmiu m Leachate Results by Leaching Test.................... 58

5-39 Ranges of Fly Ash Chromium Leachate Results by Leaching Test.................................... 59

5-40 Ranges of FGD–SDA Chromium Leachate Results by Leaching Test............................... 59

5-41 Ranges of Wet FGD Material Chromium Leachate Results by Leaching Test .................. 59

5-42 Ranges of Fly Ash Lead Leachate Results by Leaching Test ............................................. 60

5-43 Ranges of FGD–SDA Material Lead Leachate Results by Leaching Test ......................... 60

5-44 Ranges of Wet FGD Material Lead Leachate Results by Leaching Test............................ 60

5-45 Ranges of Fly Ash Nickel Leachate Results by Leaching Test .......................................... 61

5-46 Ranges of FGD-SDA Nickel Leachate Results by Leaching Test...................................... 61

5-47 Ranges of Wet FGD Material Nickel Leachate Results by Leaching Test......................... 61

5-48 Ranges of Fly Ash Selenium Leachate Results by Leaching Test...................................... 62

5-49 Ranges of FGD–SDA Selenium Leachate Results by Leaching Test................................. 62

5-50 Ranges of Wet FGD Material Selenium Leachate Results by Leaching Test..................... 62

5-51 Long-Term Ambient-Temperat ure Sample Set 1 Summary .............................................. 64

5-52 Long-Term Ambient-Temperat ure Sample Set 2 Summary .............................................. 65

5-53 Long-Term Ambient-Temperat ure Sample Set 3 Summary ............................................... 68

5-54 Long-Term Ambient-Temperat ure Sample Set 4 Summary .............................................. 69

Continued . . .ix LIST OF TABLES (continued)

5-55 Summary of Fly Ash Samples Evaluate d in Elevated-Temperature Mercury Release Experiments ........................................................................................................... 72

5-56 Summary of FGD–SDA and Wet FGD Material Samples Evaluated in Elevated-Temperature Merc ury Release Experiments........................................................ 73

5-57 Range of Fly Ash Peak Mercury Release Temperatures at Elev ated Temperature ............ 74

5-58 Range of FGD–SDA and We t FGD Material Peak Mercury Release Temperatures at Elevated Temperature ......................................................................................................... 7 4

5-59 Microbiological Release Experiment Sample Summary, Experiment 7............................. 76

5-60 Microbiological Experiment 7 Eh and pH Results.............................................................. 77

5-61 Vapor-Phase Mercury Releas e Results, Experiment 7........................................................ 77

5-62 Microbiological Leached Total Trac e Element Results, Experiment 7 .............................. 78

5-63 Summary of Vapor-Phase Mercury Rel eases from Microbiologically Mediated Experiments on Fly Ash Samples ....................................................................................... 78

5-64 Summary of Vapor-Phase Mercury Rel eases from Microbiologically Mediated Experiments on FGD–SDA and Wet FGD Filtercake Samples.......................................... 79

5-65 Field Sample Composites and Associated CCB Mercury Analysis Results, Average ....... 82

5-66 Range of Fundamental Characterization Da ta in Field Samples Collected by EERC ........ 82

5-67 Summary of Mercury Fluxes Measured from Landfill Facilities........................................ 83

5-68 Summary of Scaling of Emi ssions Using Field Site Data................................................... 84

5-69 Comparison of Scaling of Hg Flux Using In Situ Data from Three Landfill Sites............. 85

5-70 Average CCB Landfill Mercury Readings and Standard Deviation ................................... 87

5-71 Alternative Field Task (CCB–soil) Elemental Mercury Results Summary ........................ 88

5-72 Alternative field task (CCB–soil) Organomercury Results Summary ................................ 89

5-73 Overall Elemental Mercury Va por Profiles in Noted Tasks ............................................... 91x NOMENCLATURE

AA atomic absorption AAS atomic absorption spectrophotometer

AC activated carbon ACI activated carbon injection

AF atomic fluorescence ASTM American Society for Testing and Materials

ATE air toxic element

CAA Clean Air Act

CARRC ® Coal Ash Resources Research Consortium ®
CCB coal combustion by-product CVAAS cold-vapor atomic absorption spectrometry CVAFS cold-vapor atomic fluorescence spectrometry DMA direct mercury analyzer DOE U.S. Department of Energy EA enhancing agent EERC Energy & Environmental Research Center EPA U.S. Environmental Protection Agency ESP electrostatic precipitator FGD flue gas desulfurization GC gas chromatography HDPE high-density polyethylene

HNO 3 nitric acid ICP–AES inductively coupled pl asma–atomic emission spectroscopy ICP–MS inductively coupled plasma–mass spectroscopy KCl potassium chloride LLQ lower level of quantitation LOI loss-on-ignition LTL long-term leaching MPN most probable number MWLP mine water leaching procedure NA not applicable NETL National Energy Technology Laboratory

NMLRC National Mine Land Reclamation Center

NO

x nitrogen oxides NQ not quantitated

NT not tested ORD Office of Research and Development pc pulverized coal PCD pollution control device PDW primary drinking water PP pyrophosphate

PRB Powder River Basin PTYG peptone–tryptone–yeast extract–glucosexi PYG peptone–yeast extract–glucose RCRA Resource Conservation and Recovery Act SBLP serial batch leaching procedure SCR selective catalytic reduction SDA spray dryer absorber SGLP synthetic groundwater leaching procedure

SO

x sulfur oxides

SO 2 sulfur dioxide SPME solid-phase microextraction TCLP toxicity character istic leaching procedure UND University of North Dakota UNR University of Nevada–Reno WVWRI West Virginia Water Research Institutexii MERCURY AND AIR TOXIC ELEMENT IMP ACTS OF COAL COMBUSTION BYPRODUCT DISPOSAL AND UTILIZATION

EXECUTIVE SUMMARY

The University of North Dakota Energy & Environmental Research Center (EERC) conducted a laboratory and field in vestigation designed to evaluate the impact of mercury and other air toxic elements (ATEs) on the manageme nt of coal combustion by-products (CCBs). Key objectives were:

• To determine the release potential of me rcury and other selected ATEs from CCBs under specific envir onmental conditions.

• To increase the database of informati on on mercury and other ATE releases for CCBs.

• To develop comparative laboratory and field data.

• To develop appropriate la boratory and field protocols to measure mercury and ATE

releases from CCBs.

The multiyear study comprised several tasks, including laboratory methods development and selection, sample selection, sample charact erization, laboratory rele ase experiments, and measurement of mercury rele ases at a field site.

Laboratory tasks were designed and performed to address funda mental issues critical to determining the release of these constituents over the life cycle of CCBs in a variety of management scenarios. Release mechanisms addressed included:

• Direct leachability of air toxic constituents from CCBs.

• Vapor release of mercury from CCBs at ambient and elevated temperatures.

• Biologically induced leachability and vapor release of mercury and other ATEs from

CCBs.

Experimental

The experimental component of this project was important to accomplishing the work in this project since standard expe rimental protocols were not available at the time the project was initiated. Throughout the duration of the project, the research staff continued efforts to select and develop experimental protocols to simulate me rcury and ATE releases under varying conditions and the analytical methods require d to quantitate those releases.

Multiple leaching procedures were used to evaluate the potential mobility of mercury and

other ATEs from the CCBs obtained for use in the project. Developmen t of laboratory methodsxiii to evaluate vapor-phase mercury releases under ambient and microbiologically mediated conditions continued throughout the project. Methods for quantitati on of mercury collected from vapor-phase release experiments and field samp ling were developed in parallel with those efforts. Analytical tools were also used to quan titate and speciate organomercury compounds primarily in vapor-phase releases from laboratory experiments.

Using the experimental protoc ols selected and developed, a large number of samples were evaluated to determine if there was potential fo r mercury and other ATEs to be released from those samples under conditions to which CCBs woul d be expected to be exposed in typical management activities.

Results

The results of this project were dependent on the careful selection and collection of samples for inclusion in the laboratory evaluati ons performed for this task. Identification and

basic characterization information was collected and generated for the samples in the final sample set, which included several paired sample sets that were obtained at facilities that were demonstrating mercury emission control technol ogies. A paired sample set included a baseline sample collected under normal operating conditions and one or more test samples collected during demonstration of mercury control. A su mmary of the samples included in the study is shown in Table ES-1, and the paired sa mple sets are listed in Table ES-2.

Total mercury content was determined for nearly all samples in the sample set, and total

elemental concentrations of the ATEs evaluate d in this project (ars enic, cadmium, chromium, lead, nickel, and selenium) were determined for a large number of samples in the sample set. When mercury emission controls were in place, fly ash samples exhibited consistently higher total mercury concentrations. For some fly ash samples collected from systems with mercury emission controls in place, selenium was also elevated. This was most noteworthy in samples collected from mercury emission control systems where activated carbon (AC) was injected after the primary particulate control device. It was determined that the total concentrations of all elements, except mercury and seleni um, were similar for fly ash and for flue gas desulfurization– spray dryer absorber (FGD–SDA) material sa mples generated with and without mercury emission controls present. While no wet FGD material samples were collected from systems with mercury emission controls in place, the total elemental data for these materials indicated significantly higher levels of most ATEs in wet FGD material + fly ash (fixated wet FGD material).

The moisture content and loss on ignition (LOI) of solid CCBs were determined as part of

the fundamental characteri zation. It has long been known that LO I is not a direct measurement of carbon content of fly ash; however, when AC is bei ng added to fly ash, as with most test samples evaluated in this project, the LOI value typically reflected the amount of carbon present in a fly ash sample. Fly ash samples collected from me rcury control technology testing exhibited LOI values ranging from 0.59% to 24.4%. Fly ash without mercury control had LOI ranging from 0.22% to 21.2%. These ranges were similar, and the highest LOI values were atypical of the samples evaluated, although the fly ash samples co llected in demonstrations where the AC wasxiv Table ES-1. Summary of Project Samples and Fundamental Characterization Data

Coal Type Type of SO 2 Control No. of Samples Sample Type with Hg Control Description 24-hour pH Range LOI Range, % Total Hg

Concentration

Range, μg/g

Bituminous No SO 2 control 21 Fly ash 5.52–12.65 0.47–21.2 <0.01–0.685

6 Fly ash + AC (post-primary

PCD 1 ) 3.99–9.20 12.6–24.4 0.742–120

2 Fly ash + AC (pre-primary PCD) NT 2 NT NT Wet Mg- enhanced lime 2 FGD gypsum 7.75–7.88 1.22–1.92 0.032–0.044

Wet limestone –

forced oxidation 3 FGD gypsum 7.72–7.95 1.60–2.26 0.043–0.103

Wet limestone –

nonoxidized 3 FGD filtercake 7.70–7.88 4.20–6.19 0.162–0.305

3 Fixated FGD 10.50–12.43 3.11–4.17 0.136–0.249

Subbituminous No SO 2 3 Fly ash 12.27–12.56 0.32–1.08 0.261–1.22

4 Fly ash + AC (pre-primary PCD) 10.95–11.90 2.28–4.14 1.09–5.81

SDA 1 FGD–SDA 12.22 2.07 0.105 Lignite No SO 2 control 13 Fly ash 10.50–12.74 0.22–7.48 <0.01–0.878

8 Fly ash + AC (post-primary PCD) 10.52–11.41 0.59–13.2 0.147–64.5

6 Fly ash + AC (pre-primary PCD) 11.86–12.61 0.96–4.21 0.225–12.7

3 Fly ash + EA 3 + AC (pre-primary PCD) 12.29–12.77 1.04–2.49 0.287–0.640 1 Fly ash + EA 11.77 1.70 0.717

SDA 3 FGD–SDA 12.50 0.95–12.5 <0.01–2.55

SDA

1 FGD–SDA +EA + AC (preSDA) 12.54 1.12 0.332

1 Pollution control device.

2 Not tested.

3 Enhancing agent.xv Table ES-2. Paired Samples and F undamental Characterization Data ID No. Sample Type 24-hour pH LOI, % Hg, μg/g 02-070 Fly ash 8.50 5.87 0.194 02-069 Fly ash + AC (post-primary PCD) 8.43 12.60 0.742 02-072 Fly ash 8.83 5.29 0.163 02-071 Fly ash + AC (post-primary PCD) 8.63 17.22 0.975 03-061 Fly ash 12.56 1.04 0.578 03-060 Fly ash + AC (pre-primary PCD) 11.90 2.38 1.86 04-035 Fly ash 12.74 2.46 0.159 04-036 Fly ash + EA + AC (pre-primary PCD) 12.77 2.33 0.287

05-001 Fly ash 12.51 0.90 <0.01 05-003 Fly ash + EA + AC (pre-SDA) 12.29 1.04 0.565 05-005 Fly ash 11.57 1.29 0.431 05-017 Fly ash + EA 11.77 1.70 0.717 05-038 Fly ash 11.73 0.22 0.104 05-013 Fly ash + AC (post-primary PCD) 11.33 13.2 39.0 05-023 Fly ash + AC (pre-primary PCD) 12.00 3.84 12.7 05-024 Fly ash + AC (post-primary PCD) 11.41 9.45 35.9 05-025 Fly ash + AC (pre-primary PCD) 11.99 3.19 12.6 05-040 Fly ash + AC (post-primary PCD) 11.36 9.68 44.5 06-001 Fly ash + AC (post-primary PCD) 11.37 11.6 64.5 05-002 Fly ash + FGD–SDA 12.50 0.95 <0.0105-004 Fly ash + FGD–SDA + EA + AC (preSDA) 12.54 1.12 0.332

injected after the primary PCD had the highest LOI values. For that type of ACI (activated carbon injection), a portion of the fly ash produced is collected in the PCD, and a typically small amount of fly ash that passes through the PCD remains in the flue ga s stream to the point of ACI, resulting in a higher AC content in the fly ash + AC stream. For FGD–SDA samples, the LOI is likely dependent on the LOI of the fly ash thatis incorporated into the FGD–SDA final byproduct material.

In an effort to learn more about the im pact of carbon forms on mercury capture and potential release, an evaluation of the carbon forms present in several fly ash samples was performed. The three major morphological carbon forms are inertinite, isotropic coke, and anisotropic coke, and each exhib its distinct and pred ictable physical propert ies. The reactivity

series of these carbon forms is:

anisotropic coke > isotropic coke > inertinite

Fly ash samples with AC present contained mo re reactive carbon forms, indicating that the presence of high-sorbing carbon forms can be an indicator of elevated mercury in fly ash samples and that AC contains these high-sorbing carbon forms.xvi The pH of all samples of sufficient quantity was determined, and since the pH of a material can influence the leaching prof ile and may impact the performance in certain utilization scenarios, including bulk placement in engineered fills, several pH measurements were made to develop the most accurate pH data possible.

On review of pH data by coal type, the following observations were made:

• Eastern bituminous fly ash samples exhibited a wide range of pH values in all tests. This range was greater in the fly ash samples without AC than with AC.

• The South American and western bituminous fly ash sample pH ranges were narrower and more similar to those of subbituminous and lignite fly ash samples than eastern bituminous fly ash samples. All fly ash + AC (pre-primary PCD) pH values for the South American bituminous, subbituminous, a nd lignite samples in the project were

similar.

• For some fly ash samples, the pH changed significantly over time.

The pH development data are interesting because pH is a primary factor in leachability and an indicator of the potential for secondary hydration phases to imp act leachability and engineering performance. These data suggested that pH measurements for CCBs should include an equilibration time of at least 24 hours. The pH values reported for all FGD–SDA samples fell within a narrow range regardless of the presence of AC. The pH for these samples is primarily a result of the presence of unreacted sorbent, which is present as calcium hydroxide. Calcium hydroxide has a pH of 12.4, which is very similar to the pH values measured in the FGD–SDA samples. The ranges of pH values of FGD materials and liquids were acidic to near-neutral pH, with the exception of the fixated wet FGD materials.

The release of constituents found in CCBs is most likely to occur through exposure to water or direct leaching. Laboratory leaching was performed using multiple tests (toxicity characteristic leaching proce dure [TCLP, U.S. Environmenta l Protection Agency Method 1311], synthetic groundwater leaching procedure [SGLP] , and long-term leaching [LTL] with 30- and 60-day equilibration periods) on a large number of the samples assembled for this project. Mercury and other ATEs were determined on leach ates. The fly ash leachi ng data are included in

Table ES-3.

Leaching results indicated that mercury is not readily leachable from fly ash, fly ash + AC and/or EA, FGD–SDA samples, and wet FGD mate rials. Most samples had leachate mercury concentrations below the 0.01-μg/L analytical method reporting limit. Short-term (18-hour SGLP) leaching results fr om fly ash samples collected from systems without mercury emission controls in place are shown in Figure ES-1. Figure ES-2 shows the 18-hour SGLP mercuryleaching data for fly ash + AC and/or EA samples plotted against the total mercury content of the sample. Results of short- and long-term leaching for fly ash indicated that total mercury content

did not correlate with leachate mercury concentrations. The results plotted in Figure ES-2 indicated that the higher total co ncentrations of mercur y associated with the presence of AC were stable and not readily released through leaching.xvii Table ES-3. Ranges of Leachate Results for Fly Ash, μg/L

Element Fly Ash Fly Ash + AC (pre-primary PCD) Fly Ash + EA +AC (preprimary PCD) Fly Ash + EA Fly Ash + AC (post-primary PCD)

As <2–336 <2–16.3 <2–15.2 46.3–95.9 8.1–842

Cd <0.2–8.30 <0.2–1.49 <0.2–0.39 <0.3–2.68 0.85–2.46

Cr 1.40–277 3.60–560 <2–134 182–211 17.3–680

Pb <0.001–8.50 <0.001–3.00 <0.001–3.00 <2 <2 Hg <0.01–0.325 <0.01–0.068 <0.01–0.061 <0.01–0.02 <0.01–0.07

Ni <2–80.6 <2–23.1 <2–25.2 <2–2.8 <2–23.4

Se <2–514 <2–147 <2–47.2 <4–97.0 45.2–8620 pH 3.54–12.81 3.80–12.60 12.21–12.61 11.69–12.01 3.79–11.82

Figure ES-1. Fly ash 18-hour SGLP leachate merc ury plotted against total mercury content.xviii Figure ES-2 Fly ash + AC and/or EA 18-hour SGLP leachate mercury plotted against total
mercury content.

In leachate from FGD–SDA samples collec ted both with and without mercury emission controls in place, mercury was measured either at very low concentrations or was below the analytical reporting limit. As noted for fly as h, no correlation between th e total and leachate mercury concentrations was observed.

Mercury leachate concentrations from the F GD materials were also generally low, but the

18-hour SGLP results for the wet FGD filtercake a nd fixated wet FGD materi al were higher than the other wet FGD materials, FGD–SDA, and fly ash samples. Leaching of FGD gypsum resulted in the lowest mercury leachate concentr ations of all the wet FGD material samples.

The laboratory leaching results all indicated th at mercury is expected to be stable on CCBs when exposed to water. The potential for mercury to leach from CCBs is very low and is not expected to impact current fly ash management practices.

Selenium was the only ATE other than merc ury identified as having increased total concentration in some fly ash + AC samples. Specifically, fly ash + AC samples where the AC was injected post-primary PCD ex hibited an elevated total sele nium content compared to the baseline for the single paired sample set of that type. Other fly ash paired samples that had the AC injected before the primary PCD did not ex hibit this notable increase in total selenium content. In paired samples, selenium leaching was elevated in the short-term leachates with higher total selenium content; how ever, leachate selenium concentrations generally decreased in long-term leachates.xix Arsenic leachate concentrations of fly ash + AC (pre-primary PCD), fly ash + EA + AC (pre-primary PCD), and fly ash + EA all were measured to be within the range reported for leachates from fly ash only. Total arsenic was not elevated in any samples with AC or EA present. For one paired fly ash and fly ash + AC (post-primary PCD) sample set, increased

leachate arsenic concentrations were noted for se veral of the fly ash + AC test samples even though total arsenic concentrations were similar. Arsenic mobility from all FGD–SDA samples

and wet FGD materials evaluated was low.

Leaching results for cadmium, chromium, lea d, and nickel generally indicated that these elements had very low leachability in all sa mple types with and without mercury emission controls in place.

Ambient and elevated-temperature vapor-pha se release of mercury was determined in laboratory experiments. Ambient-temperature expe riments were performed in batches and were run for up to 200 days with mercur y measurements taken at interv als. The data indicated that some samples released mercury and some sample s sorbed mercury. An example of results from the ambient-temperature experime nts is shown in Figure ES-3.

The sample set shown in Figure ES-3 include d fly ash, fly ash + AC (pre-primary PCD), and FGD–SDA samples from eastern bituminous, Powder River Basin (PRB) subbituminous, and lignite coal. One paired sample set with a ba seline fly ash (03-060) and a fly ash + AC test

Figure ES-3. Sample Set 1 (194-da y) long-term ambient-temperatur e mercury release or sorption as related to blank values, pg/g/day. Positive values indicate release, and negative values indicate sorption of mercury. Duplicat e bottles are represented.xx sample (03-061) was evaluated. Additional experi ments provided similar results with fly ash samples collected both with and without mercur y emission controls in place exhibiting sorption of mercury more commonly than release. Over the duration of the experiments, the rate of mercury typically decreased for all fly ash samp les. FGD–SDA and wet FGD materials typically released mercury, and wet FGD materials exhibi ted a different release profile than fly ash samples, releasing mercury at a higher rate and for a longer duration. Following extensive exposure to ambient air, some of the wet FGD material samples showed sorption of mercury. Release/sorption rates were extremely low for all samples evaluated.

Fly ash samples were evaluated for the real-t ime elevated-temperature release of mercury. Thermal desorption curves provided a comparativ e means of evaluating the elevated-temperature release of mercury. Fly ash samp les subjected to the elevated-temperature regime typically generated either one or two mercury peaks, w ith four being the maxi mum number of peaks identified for fly ash. Mercury was released at temperatures ranging from 256° to 750°C. Some samples, predominantly eastern bituminous fly ash samples with a LOI greater than 3% or fly ash + AC (post-primary PCD), continued to s how increasing mercury release at 750°C. As shown in the sample thermal desorption mercury curve (Figure ES-4), the first peak recorded was typically sharp and well defined. Following p eaks, where recorded, tended to show slightly less definition and were usually broader, although the absorption could be higher.

Samples with AC were more difficult to evaluate for elevated-temperature mercury releases, but sorbents that contained other comp ounds, such as halogens or sulfur, also offered analytical challenges. While sample identifications did not always indicate th e exact nature of the

Figure ES-4. Typical two-peak merc ury desorption curve for fly ash.xxi AC used, samples of this type were expected to produce a thermal curve containing multiple peaks. Multiple peaks were noted in a signific ant number of fly ash samples and were likely because of the presence of multiple mercury compounds in the samples.

Multiple project samples were evaluated for microbiologically mediated mercury leaching and vapor-phase release. These experiments we re challenging to carry out because of the requirements to keep the microbe s active, the presence of fungi , and analytical interferences. Higher vapor-phase releases of mercury were measured for bot h elemental and organomercury for all samples evaluated in systems under aerobi c conditions compared to those with anaerobic

conditions. FGD–SDA and wet FGD filtercake samples exhibi ted significantly higher vaporphase mercury release rates than the fly as h samples evaluated, and the FGD–SDA sample evaluated had the highest releas e rate of vapor-phase mercury. Methylation of mercury did predictably occur in the experimental systems, but the apparent rate and resultant concentrations of methylmercury were extremely small.

A field task was accomplished in two subtasks : 1) Evaluation of Vapor-Phase Mercury at CCB Disposal Sites and 2) Sma ll-Scale Vapor-Phase Mercury Release from Soil–Ash Mixtures.

The first subtask of the fi eld investigation task was performed at CCB management facilities associated with a ligni te-fired power plant where materials were collected for laboratory characterization and in situ mercury fluxes were measured by two methods. Even though the substrates measured varied slightly between th e two types of measurements, a comparison of the results indicated good agreement for total mercur y flux relative to substr ate type as noted in

Table ES-4.

An evaluation of the impact of the intera ction between soil and CCBs on mercury release from CCBs was also performed on mixtures of 20% CCB addition to a soil–peat moss sample. Elemental mercury and organomercury release m easurements were obtaine d on several samples and compared to a soil sample. The CCB–soil mi xtures generally exhi bited low levels of elemental mercury release, while the soil–peat moss sample (only one data point) sorbed elemental mercury. CCB–soil mixtures containing samples that had AC present released lower percentages of elemental mercury than those without AC present. On average, the samples with

Table ES-4. Total Mercury Field Flux Results Comparisons

EERC Measurements University of Nevada, Reno (UNR)

Measurements Wet FGD Material + Mill Rejects > Stabilized Wet FGD Material (with fly ash) > Fly Ash

> Wet FGD Material > Natural Grasslands (background soil) > Vegetated Fly Ash with Soil Cover > Bottom Ash/Mill Rejects + Wet FGD Material (sample not evaluated by UNR) Wet FGD Material + Mill Rejects > Stabilized Wet FGD Material (with fly ash) > Fly Ash > Agricultural Land (sample not evaluated by the EERC)

= Wet FGD Material > Vegetated Fly Ash with Soil Cover > Natural Grasslands (background soil)xxii AC present released mercury an order of magnitude lower percen tage than the sample from a similar coal source without AC. However, the measured elemental mercury release rate (pg mercury/g mixture/day) was high er for the fly ash + AC (post-primary PCD) samples. The results indicated that more organomercury wa s released from four of 13 replicate CCB–soil

mixture bottles than from the bottle containing only the soil–peat moss sample. Allorganomercury releases were low. Again, the samples with AC generally exhibited a lowerpercentage release of organomercury than thos e without AC present, although the difference was

not as consistent as that observ ed for elemental mercury releases.

CONCLUSIONS

Conclusions drawn for the extensive labor atory and field work performed under this project can be summarized as follows:

• Results for baseline fly ash or FGD–SDA and test samples with AC indicated that total mercury content was higher in the test samples.

• The total selenium content was higher for the fly ash samples + AC (post-primary PCD) test samples than the baseline fly ash.

• Total concentrations of arsenic, cadmium, chromium, lead, and nickel were similar for all fly ash samples and for FGD–SDA samples collected from systems with or without mercury emission controls in place.

• Direct leaching tests indicated that mercur y was not readily leached from fly ash or

FGD materials. Leachate merc ury concentrations were below the 0.01-μg/L analytical reporting limit for most samples evaluated.

• Mercury leachate concentra tions did not correlate to total mercury concentrations.

• When exposed to ambient-temperature air in laboratory experiments, fly ash samples

either released or sorbed small amounts of mercury. Samples containing unburned or AC tended to sorb mercury in ambient- temperature vapor-phase experiments.

• Laboratory data indicated that the potential for ambi ent-temperature vapor-phase mercury releases from CCBs are unlikely to impact atmospheric mercury loading.

• Mercury was not released to the vapor phase at temperatures be low 250°C in elevatedtemperature experiments, but for most samples, 100% of the mercury on the CCB was released by 750°C.

• Under microbiologically mediated conditions , only very low levels of elemental and organomercury were released in the vapor phase and leach ate, although more elemental mercury was released.xxiii • Field experiments at a lignite CCB dispos al site indicated lo w-level vapor-phase releases of mercury, as was ge nerally noted in laboratory ex periments for lignite fly ash samples. Releases from FGD materials we re noted both in laboratory and field

measurements.

• Laboratory methods were developed to ev aluate the potential for mercury releases

under several release mechanisms.1 MERCURY AND AIR TOXIC ELEMENT IMP ACTS OF COAL COMBUSTION BYPRODUCT DISPOSAL AND UTILIZATION

1.0 INTRODUCTION

Research has been under way for many year s at the Univeristy of North Dakota (UND) Energy & Environmental Research Center (EERC) and elsewhere to evaluate the environmental performance of coal combustion by-products (CCBs) from coal-based combustion systems (ADA-ES, Inc., 2003; Carey et al., 1999; Energy & Environmen tal Research Center, 2005; Gustin and Ladwig, 2004; Hassett, 1994; Hasse tt and Heebink, 2002, 2007; Hassett et al., 2002, 2003, 2004, 2005; Heebink and Hassett, 2002; Heeb ink et al., 2004, 2006; Hower et al., 2004; Keating and Chaisson, 1999; Laudal et al., 2000, 2001; Pavlish, 1999; Pflughoeft-Hassett et al., 1996, 2004; Sanchez et al., 2006; Schwalb and With um, 2003; Xin et al., 2006). A majority of this work has focused on the mobility of trace constituents from CCBs into the environment

when these materials are beneficia lly used, especially when they are used in soil stabilization, engineered fill, or mine reclamation applications . Much of this work has been driven by the 1970 Clean Air Act (CAA), which brought significant changes to the federal air quality program requiring the U.S. Environmental Protection Agen cy (EPA) to establis h national air quality standards as well as national standards for significant new pollution sources and for all facilities emitting hazardous substances. The regulation of CCBs has been closely tied to environmental regulation of coal-fired power plants in the United States. Pa rticulate control, flue gas desulfurization (FGD), and strategi es to reduce nitrogen oxide emi ssions have all influenced the type and characteristics of CC Bs being produced. The characteristics and performance of CCBs were evaluated under a mandate from EPA, and as a result, a final regulatory determination was made by EPA for fly ash, bottom ash, boiler sla g, and FGD material, which became effective September 2, 1993 . The rule stated that regul ation of CCBs generated by coal-fired electric utilities and independent power producers as hazardous waste is unwarranted and that the materials will remain exempt from regulation as a hazardou s waste under the Resource Conservation and Recovery Act (RCRA). This de termination was upheld in a s econd EPA report in 1999, which focused on the management of fluidized-bed com bustion wastes, low-volume wastes, pyrites, and comanaged wastes for which EPA determined that these materials would continue to be exempted from regulation under Subtitle C for hazardous wastes.

Significant work was performed and data reviewed for the 1993 and 1999 EPA

determinations on CCBs. Review of those data indicated that the information on mercury in CCBs and its potential to be re leased into the environment wa s limited because the standard analytical methods used were generally not sensitive enough to measure mercury in CCBs or CCB leachates. This lack of quant itative data on the mercury cont ent of and release from CCBs coupled with the understanding that coal-based power plant mercury emi ssions would likely be regulated in the future and that mercury emi ssion control strategies would likely impact the

character and behavior of the CCBs provide the motivation for the work undertaken in this project.

The scope of work was devel oped to provide data on the environmental acceptability of CCBs produced in systems with conventional and advanced emission controls by evaluating the2 release of air toxic el ements (ATEs) from CCB samples unde r controlled laboratory conditions

and in select utilization a nd disposal field settings.

It was the goal of the project to compare th e mercury and ATE release data generated from CCBs as currently produced and produced with advanced emission controls in place. The comparative data would provide a better unders tanding of the environmental performance of CCBs potentially to be generated with mercury em ission controls in place. The project included

work to:

• Provide comparative information on CCBs from systems with various emission controls, which will aid util ities in selecting emission c ontrol technologies consistent with existing CCB management plans.

• Develop scientifically sound experimental pr otocols for determining air toxic releases from CCBs based on CCB propertie s and management scenarios.

• Provide information to the state and fede ral agencies that regulate disposal and utilization options.

Laboratory tasks addressed three areas: 1) dir ect leachability of air t oxic constituents from CCBs, 2) vapor release of merc ury from CCBs at ambient and elevated temperatures, and 3) microbiologically induced leach ability and vapor release of Hg and other ATEs from CCBs. A field task addressed mercury release at CCB management site s. The laboratory tasks were accomplished in conjunction with development of reliable methods to determine the release of

ATEs from CCBs. While laborator y leaching has long been used to evaluate the mobility of various constituents from CCBs, the evaluation of vapor-phase transport and microbiologically mediated releases of ATEs required continue d method development throughout most of the project. Development and use of appropriate met hods to develop a project data set on currently produced CCBs and CCBs produced under expe rimental/simulated conditions provided an opportunity for the CCB industry to become aware of the potential impacts of mercury emission technologies on the CCBs produced, the expected environmental performance, and impacts to current CCB management strategies.

On initiation of this project, it was hypothesi zed that if CCBs as currently produced and from systems with proposed mercury emission c ontrol systems in place were found to exhibit comparable environmental performance, standard management scenarios could continue to be employed and CCB utilization could be expected to increase even after implementation of mercury emission controls. It was not the focus of this project to evaluate the impact of specific sorbents on the engineering perfor mance of CCBs; however, over the course of this project, the EERC and others (Heebink et al., 2006; Locker t et al., 2005; ADA-ES, In c., 2003; Gasiorowski et al., 2003) did find that the presence of activated carbon (AC) in fly ash is expected to impact the use of fly ash in concrete because of the re activity of the AC and interaction with chemical

admixtures used in concrete.

The presence of Hg and other ATEs in CCBs has raised concern by state regulatory agencies (Federal Register, 2000) and citizen gr oups about the potential environmental stability3 of these elements under disposal and utilization conditions. Th is project has addressed the technical aspects of that concern, and it is important that the results of this study be communicated with the CCB industry, the regulat ory community, and other stakeholders. The project results are expected to allow CCB managers and marketers to better evaluate management options for CCBs that may be produ ced after implementation of mercury emission

controls. The data can also serve to aid in the selection of mercury emi ssion controls for those CCB producers that manage their CCBs primarily through marketing.

2.0 BACKGROUND

Recent projections from the Energy Informati on Administration indicate that U.S. demand for energy will increase from 97.3 quadrillion to 130.1 quadrillion Btu between 2001 and 2020, reflecting an annual growth rate of 1.5%. By 2025, total energy consumption is projected to reach 139.1 quadrillion Btu (Energy Information Administration, 2004). Fo ssil fuel combustion, including the burning of coal, natural gas, or oil, provides about 85% of the present energy production in the United States. Of this amount, over 50% is provided by coal-fired utilities (Energy Information Administration, 2004). As a result of energy production from coal, CCBs are generated, and CCBs, as produced in the Unite d States, are primarily a result of emission control technologies installed to meet emission regulations.

Emission regulations first mandated reductio n of particulate matter released to the atmosphere by utilities, which requi red utilities to install collection devices for generated fly ash. Later emission regulations significant to CCB production mandated limits on sulfur oxide (SO

x ) emissions. As a result, utilities using high-sulfur coal could change coal sources, resulting in a different by-product character or scrub the fl ue gas using sorbents to remove the SO

x gases. The result of FGD was high volumes of spent FGD sorbent material. There is a wide range of FGD technologies, so FGD materials have broadly varied characteri stics but generally contain high

concentrations of calcium and su lfur. Currently, utilities are re sponding to regulations placing limits on nitrogen oxide (NO

x ) emissions, which also impacts the character of CCBs, including potentially increasing the amount of unburned car bon in fly ash or adding ammonia to the fly ash. Issues related to ATEs, including mercury, are currentl y under technical and regulatory scrutiny.

Figure 2-1 includes an excerpt from an EPA Fact Sheet entitled “EPA Proposes Options for Significantly Reducing Mercury Emissions from Electric Utilities,” in which some of the concerns about mercury are summarized. On December 14, 2000, EPA announced that it would regulate mercury emissions from coal- and oil- fired electric utility steam-generating power plants (Federal Register, 2000); propose re gulations by December 15, 2003; and finalize regulations by December 15, 2004. On December 15, 2003, EPA signed the Utility Mercury Reductions proposal, which seeks comments on two approaches for reducing mercury by up to nearly 70%. On March 15, 2005, EPA issued the firs t federal rule to permanently cap and reduce mercury emissions from coal-fired power plants (a power plant is define d as an electrical4 Figure 2-1. EPA information on mercury emissi ons (U.S. Environmental Protection Agency, 2003).

generating facility that provides >25 MW e ). The rule is a market-based cap-and-trade program (CAA Section 111) and is similar to the program in place for sulfur dioxide (SO 2 ). The rule is to be administered in two phases. The first phase places a cap of 38 tons per year of mercury beginning in 2010. The second phase sets a final cap of 15 tons by 2018. Coal-fired power plants currently emit about 48 tons per ye ar; therefore, the reduction in mercury emissions will be 21% and 69%, respectively.

The reduction of emissions at coal-fired pow er plants has historically impacted the quantity and character of resul ting CCBs, and with changing quantiti es and characteristics, the management and associated costs have also been impacted. One of the most noteworthy industrywide changes occurred when FGD syst ems were installed in the 1980s and large volumes of FGD materials were produced and required management. The removal or reduction of mercury emissions at coal-f ired power plants also has high potential to impact CCB management because several proposed mercury em ission control technologie s involve the use of solid sorbents that will likely be introduced in the flue gas and collected with the fly ash. Other candidate emission control technologies fo cus on increasing the mercury sorbed on FGD materials. These mercury emission control tech nologies will impact th e mercury content of CCBs. The question that this project was design ed to answer is, Will the changes in CCBs associated with mercury emission controls cha nge the management options for those CCBs as they relate to the potential release of mercur y? The U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) (2007) evaluate d the cost of activated carbon injection (ACI) mercury control and reporte d that the incremental costs increased by a fraction of 1.5– 3 when including impacts to CCBs in addition to implementation costs. DOE NETL reported costs for seven different power plant case studies, and when co sts of impacts to CCBs were5 included in the economic evaluation, four case st udies had costs exceeding DOE’s cost target of $45,000/lb Hg removed.

Since the large volumes of CCBs produced an nually in the United States are managed either by disposal or utilizati on, the design of various tasks in this project focused on simulating potential behavior of CCBs in environments wh ere they are typically managed. Examples of

utilization scenarios include:

• The use of fly ash in concrete, soil stabiliza tion, or fills that could be exposed to natural

waters or to microbial action.

• The use of FGD gypsum in wallboard, where it may be exposed to high temperatures in production or to natura l water under disposal.

• The use of fly ash in cement clinker production, where it would be exposed to extremely high temperatures.

• The use of FGD gypsum or fly ash as an agri cultural soil amendment or mine fill, where it would be exposed to natural wa ter and, potentially, microbial action.

In order to adequately address the potential for release of mercury from CCBs, sorbents, and combinations, release mechanisms that must be evaluated include leaching, elevated- and ambient-temperature vapor-phase releases, and microbiologically mediated releases. The EERC initiated research on the potenti al release of mercury from CCBs in 1999 and found that methods for evaluating the release of me rcury from CCBs using these mechanisms were not documented in the scientific literature, with the exception of leaching. As a result, the EERC initiated a program under EPA’s Center for Air Toxic Metals ® and the Coal Ash Resources Research

Consortium ® (CARRC ® ) to develop laboratory methods that would provide information on the potential for CCBs to release mercury and othe r ATEs under conditions associated with the proposed release mechanisms of di rect leaching, direct ambient- and elevated-temperature vaporphase release, and microbiologically medi ated leaching and vapor-phase release.

3.0 OBJECTIVES

The goal of the proposed effort was to evalua te the impact of mercury and other ATEs on the management of CCBs. Supporting objectives ar e to 1) determine the release potential of selected ATEs, including mercury and arseni c, from CCBs under specific environmental conditions; 2) increase the data base of information on mercury and other ATE releases for CCBs; 3) develop comparative laboratory and fiel d data; and 4) develop appropriate laboratory and field protocols.

The specific mechanisms of ATE releases eval uated were leaching rele ases, vapor releases to the atmosphere, and biologically induced leaching and vapor releases.6 4.0 EXPERIMENTAL

4.1 Literature Search

The literature search task was designed origin ally to allow the preparation of an annotated bibliography that included literat ure on the following topic areas:

• Mercury and other ATE content of CCBs

• The mobility/stability of those elements from/on CCBs

• Emerging mercury control technologies, especi ally as they would potentially impact the characteristics or composition of CCBs

In the first project year, it was agreed by proj ect sponsors and researchers that the use of an

online database to store and retrieve the assemb led documents would have greater value to the project, so the approach was modified to enable the development of an online database for the literature collected, allowing project sponsors access to all information gathered.

Throughout the duration of the project, the pr oject team collected and reviewed various documents that pertained to mercury and ot her ATEs. The documents were gleaned from journals, symposium and conference proceedings, news articles, and several other sources. Both

national and international documents were collected.

4.2 Analytical Methods Selection

To evaluate the potential for release of me rcury and other ATEs from CCBs, appropriate methods were required, including both experimental methods and analytical methods. This task

focused on the selection and cont inued development of experiment al protocols to simulate Hg and ATE releases under varying conditions and th e analytical methods required to quantitate

those releases.

4.3 Sample Identification and Selection

Sample identification and selection ranked hi gh in importance in conjunction with other critical components of the project because the results of laboratory tests and experiments are sample-specific. In order for laboratory results to be valid and relate to real-world applications, CCBs evaluated must be representative of those exp ected to be generated at full-scale coal-fired power plants.

The objective of this task was to identify, select, and obtain CCB samples of appropriate type, quality, and quantity for use in the laborat ory evaluation of the stability of mercury and

other ATEs.7 4.3.1 Sample Prioritization

A sample prioritization was developed based on the behavior of mercury. As shown in Figure 4-1, mercury is a highl y volatile element that, along with fluorine and chlorine, is expected to be essentiall y 100% associated with the flue gas a nd carried out of the stack. For this reason, mercury that may be associated with CCBs has the greatest likelihood of being associated with the fly ash or FGD materials. The temperatures at which bottom ash and boiler slag leave the combustion system are too high for mercury to associate with these materials, so researchers made the recommendation to project s ponsors that these materials be excluded from the sample set, and the recommendation was accepted.

Sample identification and selection activities re sulted in the preparation of a target list of samples expected to provide data from which c onclusions and generaliza tions can be drawn over the duration of the project. Sample collection was a major and ongoing task.

Samples of fly ash and FGD material from systems with conventional combustion and emission control technologies were relatively simple to access through the EERC’s CCB research program and contacts. These samples generally were collected and submitted as samples for typical utilization a pplications. Most of these sample s were collected as composites or from locations within the plant where “as-managed” samples could be accessed. These samples were most likely to represent the materials that are utilized or sent for disposal and provided the most reliable resu lts for real-world comparisons.

Figure 4-1. Categorization of trace elements a ssociated with coal ash based on volatility.8 As-managed samples were generally not available from demonstrations of mercury emission controls. Some of the mercury emissi on control demonstrations were performed on pilot-scale equipment and some were performe d on slipstreams at fu ll-scale power plants. Samples from these types of systems had the di sadvantage of not being collected with typical pollution control devices (PCDs). In cases where mercury emission control was demonstrated at full-scale power plants and collected with existing full-scale PCDs, the samples were generally collected from specific fields within the electrostatic precipitator (ESP).

At the Year 1 Project Revi ew Meeting, project sponsors and researchers discussed the advantages and disadvantages of using sample s from mercury emission control demonstrations in

this effort. In cases where the baseline and me rcury control samples were collected at the same location, the samples provided comparative data . However, these data cannot be directly compared to data generated on as-managed samp les. Hower et al. (2004) presented information on total mercury content in samples of fly ash colle cted at different locati ons at one power plant, as noted in Figure 4-2. The data indicate that samples from a single location in a full-scale power plant are unlikely to represent the merc ury content in the associated as-managed sample. Similar variations may be expected for other ATEs.

4.3.2 Sampling and Storage Procedures

The issue of obtaining and maintaining a high- quality sample for laboratory investigations is common across numerous scientific disciplines. In the area of CCB research and testing, some sampling and sample storage issues are critical to performing laboratory work that provides

information that can be translated to the r eal-world management of CCBs whether that is utilization or disposal. These i ssues can be more or less impor tant based on the type of CCB under consideration. Fly ash and FGD material s, have different sampling and storage requirements. A description of each of these materials follows:

• Fly ash is homogeneous on the macroscale ye t heterogeneous on the microscale. Further, fly ash can vary with changes in the operation of the plant over the course of hours, days, weeks, or months. For this reason, composite samples are generally recommended when fly ash is sampled. For most laboratory evaluations, fly ash is collected from a storage facilit y, a disposal site, or a truck or train car at the point of delivery. These samples, referred to as “as-managed,” are generally representative of the sample to be used or disposed of. Fly ash samples collected from specific locations in the PCD are not considered representation s of the bulk material that is used or disposed of.

• FGD material is generally a high-sulfur material but can have va rying physical and

chemical characteristics based on the t ype of FGD system and material-handling protocols. Physically, FGD mate rial can range from a very wet material to nearly dry. Generally, FGD materials to be characterized are usually collected after a dewatering step. This is especially true for FGD materi als that are being eval uated for utilization9 Figure 4-2. Mercury distri bution in a power plan t (Hower et al., 2004).

applications such as FGD gypsum for use in wallboard. The method of dewatering and collection can impact the chemical compositi on of the FGD material. FGD material that is destined for disposal may be collected either from a location referred to as the “blowdown” for the wet FGD systems or it ma y be collected at the point where it exits the transport system to the disposal site. In some instances, wet FGD material may be stabilized by the addition of fly ash or ot her reagents such as lime prior to use or disposal. In these cases, the added reagen t may impact the chemical composition and

behavior of the FGD material. FGD material from a spray dry absorber (SDA) system may have fly ash incorporated into the FGD ma terial as part of the system. In selecting and collecting FGD material samples for laboratory evaluations, the sample should represent the material as-managed, and th e laboratory personnel must be aware of special handling and reagents that may have been added.

Under ideal conditions, sample collection pr ocedures followed ASTM (American Society for Testing and Materials) Intern ational C311 procedures. The stan dard defines grab samples as samples taken at prescribed intervals over a period of time and having a mass of at least 4 lb. Grab samples can be combined to make a composite sample having a mass of at least 8 lb. According to ASTM C311, samples taken from bulk storage, railcars, or trucks may be taken by siphon tube during loading or by sampling tube from each railcar or truck. If the load is sampled at the point of discharge in to a railcar or truck, the top 8 in. must be removed.

Dry material samples (fly ash–sorbent, spent so rbent, and FGD solids) of greater than 1 gal were homogenized to create a repres entative 2- to 4-L sample that is transferred into a glass jar with Teflon-lined cap to ensure sample integrity was maintained over the dur ation of the project. Liquid FGD samples were mixed thoroughly, and a 2- to 4-L aliquot was transferred to a glass10 jar with a Teflon-lined cap. Liquid sample aliq uots were stored under refrigeration (<4°C) until the testing was completed. Homogenized subsampl es were stored in the laboratory for use throughout the project. Orig inal containers were st ored in a secure area.

Proper storage was important for maintaining the composition and integrity of the samples because the properties of the samples can ch ange with time depending on the material

characteristics.

4.3.3 Sample Collection

4.3.3.1 Sample Identification Form

In order to best categorize and interpret project results, information on the sample type, coal used, and system was needed. A sample id entification form was developed that allowed each sample submitter to easily identify system a nd sample information. All sample submitters were given the sample identification form. The sample identification form was extremely useful

in this effort because the same identification in formation is available for most project samples, facilitating data interpretation. A copy of the sample identification form is included in Appendix A.

4.3.3.2 Confidentiality

Confidentiality of sample identity was discussed with sample submitters, and when requested, confidentiality agreements were signe d. Each sample was assigned a project number, which was the primary identifier for all samp les. Other identifying information has been provided by most sample submitters through the sample submission form. That information included submitter name, location and name of power plant or pilot- or bench-scale system, fuel type, plant configuration, and so me operating information. All of these identifiers were kept confidential for this report.

4.4 Chemical and Physical Characterization

The objective of this task wa s to characterize selected samp les in order to understand the physical, engineering, and environmental performan ce of the materials and ensure that a cross section of fly ash and FGD materials was repr esented in the inves tigation. The chemical

characterization included determ ination of bulk chemical compos ition (major, minor, and trace element constituents) with a focus on the mercury and identified ATEs. In addition to mercury,

the ATEs included in the characterization an d the overall study were arsenic, cadmium, chromium, lead, nickel, and selenium. Physical characterization included loss on ignition (LOI), moisture content, pH, and carbon forms measurements. Eh was measured in leachate samples from the microbiologically mediated release e xperiment where a liquid medium was used to promote microbial growth. Data de veloped in this characterizati on task were used to aid in interpretation of the results from release experiments.11 4.4.1 Analytical Methods for Characte rization and Release Experiments

Standard methods were select ed and used for sample prepar ation and analyses where those were available and appropriate for the sample t ypes, volumes, and matrices. Sample preparation and analysis methods were modified or developed as needed where standard methods did not suit the needs of the project.

4.4.1.1 Total Mercury and Air Toxic Elements

The total mercury content of the majority of solid samples was determined using a direct mercury analyzer (DMA-80). Additionally, diges tion followed by cold-vapor atomic absorption spectrometry (CVAAS) (EPA Method 7471) (U.S . Environmental Protection Agency, 2005a)

was utilized.

The total concentrations of the other ATEs of arsenic, cadmium, chromium, lead, nickel, and selenium were determined using standard methods. Acid digestion was used on the CCB followed by detection using inductively coupl ed plasma–atomic emission spectroscopy (ICP– AES) (EPA Method 6010B) (U.S. Environmen tal Protection Agency, 2005b) or ICP–mass spectroscopy (ICP–MS) (EPA Method 6020) (U.S. Environmental Protection Agency, 2005c).

4.4.1.2 Total Bulk Chemical Composition

The major bulk composition, reported as pe rcent oxides, was dete rmined using x-ray fluorescence spectrometry. ASTM D4326-04 Standa rd Test Method for Major and Minor Elements in Coal and Coke Ash by X-Ray Fluor escence was used (ASTM International, 2004a).

4.4.1.3 LOI and Moisture Content

Standard characterization techniques were used to measure LOI and moisture content. ASTM C311-04 Standard Test Methods for Samp ling and Testing Fly Ash or Natural Pozzolans

for Use in Portland-Cement Concrete was used (ASTM International, 2004b).

4.4.1.4 pH

The pH of samples was determined using di stilled water and/or 1 M KCl. The method employing 1 M KCl was required for many types of solid samples that exhibit a double electric layer that affects the determination of pH. For this task, 25 mL of 1 M KCl solution was mixed with 10 g of CCB, and the resulting pH was measur ed and recorded. As previously noted, the pH was also determined in slurry of distilled, de ionized water. Where both methods were employed in this effort, it was noted that the pH values were similar. A comparison of these data for a relatively broad range of CCB types led researchers to conclude that it is not necessary to use 1 M KCl in determining the pH of CCBs; theref ore, remaining samples were evaluated using distilled, deionized water slurries. It is likely that the high concentration of total dissolved solids generated in the pH dete rmination eliminated the double electric layer effect that requires the use

of KCl solution in the determinati on of pH in other types of solid samples. It was found that for12 some samples especially those containing a dded carbon, up to 24 hours of equilibration was required in order to obtain a stable and accurate pH reading.

4.4.1.5 Carbon Forms

Dominant carbon forms were identified in a select group of project samples. The samples on which carbon forms were determined were pr epared by mounting in epoxy resin. The sample was dispersed in the bottom of a 1-in.-diamet er rubber cup mold. The epoxy was stained using Sudan black, which results in a hi gh contrast between the particle s of interest and the mounting medium. The surfaces to be analyzed were polishe d with incrementally smaller grits, with 1⁄4 μm being the final polishing grit used. The samples were then examined using a reflected-light microscope.

4.4.1.6 Eh

Eh was determined using a platinum elec trode with a standard reference electrode.

4.4.1.7 Methods of Measurement Speci fic to Release Experiments

4.4.1.7.1 Gold-Coated Quartz Traps

Gold-coated quartz mercury collection traps used to collect Hg from various release experiments were desorbed for analysis by h eating to approximately 500°C, and the mass of mercury released was determined using double- gold amalgamation with atomic fluorescence (AF) detection. A Brooks Rand Model III cold -vapor atomic fluorescence spectrophotometer (CVAFS) was utilized for mercur y concentration determination. Me rcury peaks were recorded to allow quantitation using an integrator.

4.4.1.7.2 Measurements of Mercury on Carbotraps

Supelco CarbotrapTM collection traps were also used in several release experiments and were analyzed for total mercury by heating to approximately 300°C, passing the released organomercury through a tube held at about 800°C, and collectin g the mercury on a gold-coated quartz trap, which was analyzed as described above.

4.5 Laboratory Evaluation of ATE Releases

Assembled samples were used in laboratory experiments focusing on specific release mechanisms of mercury and other ATEs. Primar y release mechanisms are leaching, vaporization, and biologically stimulated leaching and vaporiza tion. ATEs were evaluated including arsenic, cadmium, chromium, lead, mercury, nickel, and selenium for release through leaching. Vaporrelease experiments focused on mercury.13 4.5.1 Direct Leaching

Methods for leachability were broadly availa ble, but a review of leaching methods was required in order to ensure th at reliable results would be ge nerated. The appropriateness of individual leaching procedures is frequently de bated, and selection of leaching procedures for this effort was a key activity under this tas k. The EPA Office of Res earch and Development (ORD) developed a standard leaching protocol fo r research related to mercury release from CCBs, and the EERC participated in discussions coordinated by EPA ORD in the development of that protocol.

Leaching is the most likely mechanism of tr ansport of constituents from disposed or utilized CCBs contacted by water. Leaching is t ypically performed on CCBs to characterize them for management purposes. The leaching tests perfor med on the samples in this project were the toxicity characteristic leaching procedure (T CLP) (EPA Method 1311) (U.S. Environmental Protection Agency, 1992), the synthetic groundwa ter leaching procedure (SGLP), and long-term leaching (LTL) with 30- and 60-day equilibrati on periods (Hassett, 1998). TCLP was included because some regulatory groups continue to use TC LP results to determine whether a “waste” is hazardous. The SGLP–LTL was used because pr evious EERC work has shown it to yield scientifically valid results on CCBs includi ng reactive CCBs (Hassett, 1994; Hassett et al., 2005).

TCLP is a leaching procedure designed for the evaluation of leaching of wastes when codisposed in a sanitary landfill. Leaching with TCLP utili zes a 20:1 liquid-to-solid ratio, endover-end agitation at approximately 30 rpm, an 18-h equilibration time, and one of two

extraction fluids. The extraction fl uid used is dictated by the pH of the mate rial being leached. Extraction Fluid 1, used when the pH is below 5, is prepared by adding glacial acetic acid and sodium hydroxide to reagent wate r, and has a fluid pH of 4.93 ± 0.05. Extraction Fluid 2, used when the pH of the material is above 5, is prepar ed by adding glacial acetic acid to reagent water, resulting in a fluid pH of 2.88 ± 0.05.

The SGLP batch-leaching procedure is a relativ ely simple test that follows many of the

conditions of TCLP. The test u tilizes a 20:1 liquid-to-solid ratio, end-over-end agitation at approximately 30 rpm, an 18-h equilibration ti me, and usually employs a leaching solution consisting of water from the site, water that has b een prepared in the lab similarly to water likely to contact the CCB, or distilled, deionized water. When distilled water is used as the leaching solution for SGLP, the method is equivalent to the ASTM D3987 Standard Test Method for Shake Extraction of Solid Waste with Water (A STM International, 2006). Distilled, deionized water was used in this effort. For the long-term component of this proce dure, multiple bottles were set up and analyzed at different time interv als. A typical SGLP–LTL test might consist of 18-h, 30-day, and 60-day equilibration times. Although 60 days is often not adequate to achieve complete equilibrium, it is generally long enough to determine the concentration evolution of individual parameters. The most important factor when performing LTL is to have at least three equilibration times to determine a true trend. A draft of the SGLP–LTL method prepared for consideration by ASTM is in Appendix B.14 For all leaching procedures, th e solids were filtered from the leaching solution through a 0.45-μm filter, the pH of the resulting leachate was measured, and the leachate was preserved with hydrochloric acid (HCl) for mercury de termination and with nitric acid (HNO 3 ) for

determination of other trace elements.

Mercury leachate concentrations were dete rmined using CVAAS and CVAFS. Other trace elements were determined using ICP–MS or graphite furnace atomic absorption spectroscopy.

The SGLP method was used preferentially fo r the project samples, and where TCLP was applied, SGLP was applied for comparative pur poses. The SGLP short-term leaching procedure was applied to all samples, but for samples with a pH >10, the LTL option was also used. LTL provides the most valuable information when at least two long-term test s are run (30-day and 60-day LTL or longer as recommended) and repor ted in conjunction with SGLP results. CCBs exhibiting a high pH have the potential to unde rgo hydration reactions that can change the leaching profile with time. The EERC documented the impact of ettringite formation on leachate concentrations of several elements that are frequently present in CCBs, such as arsenic, selenium, and boron. The elements that are most lik ely to be incorporated into the ettringite structure and exhibit a change in leaching profile with time are those that are present as oxyanions at high pH. Examples of leaching profiles of high-pH CCBs for some trace constituents commonly found in CCBs ar e shown in Figures 4-3 and 4-4.

Figure 4-3. Example LTL results for boron.15 Figure 4-4. Indirect evidence of ettringite formation using SGLP and LTL (note: boron is on a secondary axis).

In Year 2, the task was expanded to incl ude participation in a DOE NETL informal interlaboratory round-robin experiment aimed at providing the industry with appropriate leaching procedures for CCBs. NETL sent a sample to all participating labor atories for evaluation. Samples were requested by the EERC from various utilities burning s ubbituminous or lignite coal to provide an additional fly ash sample for evaluation. Samples received were evaluated, and one reactive sample was selected for the experi ments and sent to partic ipants. Four leaching procedures including the 3-tier leaching protocol (Kosson et al., 2002), the serial batch leaching protocol (SBLP) developed by NETL, the SGLP and LTL with 30- and 60-day equilibration periods (Hassett, 1998), and the mine water le aching protocol (MWLP) proposed by the West Virginia Water Research Institute (WVWRI ) National Mine Land Reclamation Center (NMLRC) (Ziemkiewicz, 2005) were part of th e informal round-robin experiment. The SBLP and SGLP–LTL tests were performed on the two ash samples at the EERC. A 90-day equilibration period was include d at the EERC for this study.

4.5.2 Vapor-Phase Mercury Transport

4.5.2.1 Long-Term Ambient-Temperature Release

In order to develop a method to evaluate the potential for release of mercury from CCBs at ambient temperatures, several preliminary deci sions were made based on the practicality of performing this type of ev aluation in the laboratory:16 • Since most CCBs contain low concentrations of mercury, samples with relatively high concentrations of mercury would be used in experimental development and for initial

measurements.

• To facilitate evaluation of multiple samp les over long duration, gold-coated quartz mercury collection traps would be used to collect mercury vapor over predetermined time periods, allowing for determination of total mercury released and rate of release. A dedicated mercury analyzer was not availabl e for long-term real-time mercury release

measurements.

• In order to evaluate multiple samples with available equipment and instrumentation, released mercury was collected on analytical gold-coated quartz traps.

• Low release of mercury was anticipated, so it was decided to expos e a column of CCBs to low-mercury air rather than expose only the surface of a CCB to the ambienttemperature low-mercury air.

Using preliminary premises based on previ ous EERC work, 250-mL wi de-mouth glass test containers with bonded Teflon liner caps were us ed. Two holes were dr illed in the caps to accommodate a silicone tube for gas inlet and a Teflon outlet bulkhead fitting. The gas inlet tube extended only slightly into the container, while the outlet tube extended nearly to the bottom of

the container. A shorter outlet tube situated ab ove the sample was used for wet FGD material samples because air could not flow through the sa mple to the outlet below the sample surface.

Using these test containers, 75–200-g aliquo ts of CCB provided a column of material through which the low-mercury air could be tran sported. Breathing-quality air from a cylinder was passed through several sets of gold-coated quartz traps for mercury removal and admitted to each of the bottles through a gas distribution ma nifold that routed the gas through 0.25-mm-i.d. gas chromatography (GC) cap illary tubing to each of the individual bo ttles. The pressure drop across the GC capillary tubing allowed for the regulation of airflow through each bottle by simply adjusting the length of tubing to each bo ttle. The length of tubing was a nominal 65 cm. This length of tubing, when pr essurized to between 1 and 2 psig thr ough a gas distribution manifold, provided a convenient means of re gulating gas flow to approximately 2 cm 3 /min. Because of the variability of pa rticle sizes between different CCB samples, the sample with the initial highest gas flow was left with a 65-cm length of GC t ubing, and other samples had their tubing lengths shortened until all samples had approximately the same flow rate. The air exiting the GC tubing was given a final scrubbing to remove me rcury vapor using a gold-coated quartz trap just prior to entering the bottle containing the CCB. After entering the bottle, the air passed through the CCB and exited to a mercury collectio n tube containing two separate gold-coated quartz traps. The trap nearest th e exit bulkhead fitting, or anal ytical trap, collected mercury

released from the CCB and bottle. The second outle t, or top trap, was used to prevent mercury contamination from atmospheric mercury. Th is setup is illustrated in Figure 4-5.

The gold-coated quartz analytical trap ne arest the exit bulkhead fitting was analyzed multiple times, with the most typical sampling sc heme being one 7-day mercury vapor collection17 Figure 4-5. Ambient-temperature mercur y vapor release collection apparatus.

period followed by two consecutive 90-day mercur y vapor collection periods. The gold-coated quartz analytical traps were evaluated accordi ng to the method described in the analytical

method section. In order to determine the tota l mercury released over the duration of the experiment, the mercury results from all experimental time segments were combined, and the

container blank was subtracted. The container bla nk was determined on the empty bottles used to hold the samples.

4.5.2.2 Thermal Desorption at Elevated Temperature

Since mercury and mercury compounds are highly volatile, mercur y release from CCBs was expected when they were exposed to elevat ed temperatures. Even mercury that is sorbed onto fly ash, FGD material, or sorb ents developed to remove mercur y in flue gas was expected to have high potential to be released if exposed to high enough temperatures. Instrumental and equipment constraints existed for the physical test ing of elevated-temperature release of mercury from CCBs. These constraints included the following:

• Furnaces available for the experimental apparatus could only achieve maximum temperatures of 750°C.

• Fittings and connecting tubing needed to be heated in order to minimize the loss of mercury in the system.18 • Gas flow to remove the mercury from the h eated sample cell to the analytical cell

needed to be constant.

• Temperature ramping needed to be contro lled and consistent between sample runs.

• Detection limit of atomic absorp tion (AA)-determined sample size.

An apparatus was constructed as shown in Figure 4-6. The CCB sample was weighed into a quartz tube, with quartz wool used to keep the sample in place in the tube. Sample size varied from approximately 300 to 900 mg. The sample t ube was placed into a small tube furnace capable of achieving a maximum of 750°C. A pr ogrammed temperature controller ramped the furnace from ambient to maximum temperature at 25°C per minute. In preliminary experiments, the maximum temperature achievable was 700°C, but an improved furnace wa s incorporated into the apparatus to increase the maximum to 750°C. A nitrogen gas flow of 5 cm 3 /min was introduced into the tube furnace. As the mercury and mercury compounds desorbed from the CCB in the sample tube, the nitrogen flow carried them through the system to the electrically heated quartz analytical cell. The quartz analytical cell was operated at 800°C, allowing the detection of mercury compounds by thermally decomposing compounds to form elemental mercury, which can be detected by AA. The analytical cell at th e top of the diagram was placed in the center-focused beam path of an AA sp ectrophotometer (AAS). A mercury hollow-cathode lamp was used as the light source, and the AAS detector was set to the 253.7-nm line for mercury. A Hewlett Packard 3395 inte grator was used for data collection. Examples of thermal desorption curves generated with this method ar e shown in Figures 4-7 and 4-8. The integrator used standard algorithms to identify peaks and indicated the time of peak maximum, which is noted in Figures 4-7 and 4-8.

Figure 4-6. Mercury thermal desorption apparatus.19 Figure 4-7. Typical thermal desorption curve for fl y ash (peak time is noted in minutes for each peak recognized by the electronic integrator used for data collection).

Figure 4-8. Example of thermal de sorption curve for an FGD material (peak time is noted in minutes for each peak recognized by the electronic integrator used for data collection).20 4.5.2.3 Mercury Speciation Method

It has been hypothesized that the mercury species associated with fly ash, FGD material, or carbon might be identified using thermal desorp tion techniques. EERC researchers performed numerous experiments to confirm or refute th is hypothesis. The experi mental design focused on the use of analytical spikes using mercuric ch loride and elemental mercury. CCB samples, quartz sand, and quartz powder were all used as a base sample for these evaluations. Mercuric chloride

was dissolved in ether and then added to the ba se samples. Elemental mercury was added in a gaseous form to CCB samples. The spiked sample s were then desorbed us ing the same apparatus and protocol for the elevated-temperature vapor -phase mercury release experiments described

above.

4.5.3 Microbiologically Mediated Leac hing and Vapor-Phase Transport

4.5.3.1 Description of Initial Apparatus and Method

The first apparatus assembled to conduct micr obiologically mediated vapor-phase mercury release used a 250-mL Erlenmeyer flask fitted with an impinger in let/outlet tube, with the inlet center shortened to 6 cm below the standard tape r. Cylinder gas was passed through several sets of gold-coated quartz traps for mercury removal and admitted to each of the flasks through a gas distribution manifold that routed the gas th rough 0.25-mm GC capillary tubing to each of the individual flasks. A GC capillary length of a pproximately 60 cm, when pressurized to between 1 and 2 psig through a gas distribution manifold, provided a convenient m eans of regulating gas flow to approximately 2 cm 3 /min. The gas carried mercury vapor from the headspace of the flasks to a mercury vapor collection system at th e outlet of the flasks, c onsisting of two traps. A Supelco CarbotrapTM (for collect ion of organomercury compounds) and a gold-coated quartz trap (for collection of elemental mercury) were used to collect mercury released in the vapor phase

from the flasks.

The flasks were placed on a 16-flask wris t action shaker. The experimental matrix consisted of eight flasks under an aerobic conditions (using argon) and eight flasks under aerobic conditions (using breathing-quality air). In each se t of eight flasks, two contained only buffer,

three contained the CCB with buffer (starved), a nd three contained the CCB with buffer and glucose (fed). A 50-g aliquot of CCB was place d in the flasks, and ~100 mL of a phosphate buffer (with or without glucose, as appropriate) was added to create a neutral pH. The CCBcontaining flasks also had 100 μL of mixed bacterial culture adde d. The source of bacteria was a

mixed bacterial innoculum from a brackish wetla nd. This setup is illustrated in Figure 4-9.

4.5.3.2 Modifications of the Appar atus and Experimental Design

The apparatus as described underwent several iterations as difficulties were identified and solutions developed. The wrist-act ion shaker was abandoned, as it was inadequate to suspend the sample during the experiments. Instead of the wrist action shaker, samples were placed in Erlenmeyer flasks on a 9-place stir plate. Th is was operated for about 20 min every 3 h to maintain sample agitation over the duration of th e experiment. Additionally, the sample size was21 Figure 4-9. Early microbiologically mediated mercury vapor-phase collection apparatus utilizing a wrist action shaker to facilitate mixing.

reduced to 20 g and the buffer increased to 135 –150 mL to provide adequate sample volume for additional trace element analyses. The buffer co mposition was also altered. It was found that phosphate and nitrate interfered wi th a derivitization st ep in the determination of organomercury compounds in the solid-phase mi croextraction (SPME) proce ss using gas chromatographic separation followed by detection of the mercury compounds by AF. This technique is described in Section 4.5.3.6. The original buf fer utilized nominal concentrations of phosphate and nitrate salts. The improved buffer used only 100 ppm of phosphate and substituted potassium glutamate as the nitrogen source. This simple change app eared to remove the inte rferences. Additionally, later experiments did not involve the use of starve d control samples. In current experiments, all samples are fed with glucose. Table 4-1 su mmarizes the modificati ons and indicates the experimental difficulties that the modifications were employed to correct or improve. The final experimental apparatus used for the majority of the project microbiological experiments is illustrated in Figure 4-10.

4.5.3.3 CCB Preparation Methods

Some CCBs, especially fly ash, can be alkaline in nature. CCB alkalinity can be attributedto the dissolution of alkaline metal oxides that react with water to generate net alkalinity. Watersoluble calcium content contributes most of a CCB’s net alkalinity. This trend can be seen in the classification of fly ashes; Class C fly ash is enriched in Ca a nd Mg and subsequently generates pH values considerably higher th an Class F fly ash (e.g., pH >10).22 Table 4-1. Microbiological Rerelease Apparatus Modifications Original Experiment or Apparatus Component Difficulty or Unmet Need Modified Experiment or Apparatus Component Wrist Action Shaker, Continuous Shaking Inadequate suspension of sample. Magnetic stir plate, intermittent stirring. 50–80-gram Sample Size +

~100-mL Buffer Inadequate volume of liquid to recover for leachate analysis. ~20-gram sample + 135–

150 mL buffer. Phosphate Nitrate Buffer Solution Inte rference with the determination of the organomercury compounds in

leachate. Lower concentration of phosphate with potassium glutamate as nitrogen

source. Glucose-Fed and Starved Experiments Starved experiments did not promote microbial growth so were deemed

unnecessary. All experiments fed with glucose.

Gold-Coated Quartz Trap Followed by Carbotrap at Gas Exit (only in Experiment 1) Organomercury was trapped on the gold-coated quartz so organomercury could not be measured separately. Carbotrap was followed by gold-coated quartz trap at gas exit.

Figure 4-10. Microbiologically mediated mercury vapor-phase collection apparatus utilizing a stir plate to facilitate mixing.

In order for a CCB, or any material, to support biological activity, it must be near-neutral pH. A pH range of 6.5 to 8.5 was used for optimal microbiological activity, requiring substantial

neutralization of some CCBs. Prior to initiation of experiments, the buffer for that experiment was added to individual samples, pH of the as h–buffer mixture was measured, and an appropriate volume of acid was added over a peri od of time to achieve a neutral pH.23 4.5.3.4 Microbiological Innoculum Growth Conditions and Media

Since the microbes that promote the release of mercury are ubiquit ous, freshly collected

sediment from a local brackish wetland was used as the innoculum. This innoculum contained a variety of microbes including both aerobic and anaerobic bacteria a nd, therefore, was identified as an appropriate innoculum. The source of the innoculum was the same for all experiments.

The innoculum was prepared by using 1 g of sediment taken approximately 2 mm from the surface of the sample so that is was more likely that a high con centration of anaerobic organisms would be present. This sample was added to 10 mL of 0.9% NaCl and vortexed. This suspension was then used to inoculate the CCB slurry samples.

4.5.3.5 Experimental Incubation Conditions

Samples were allowed to incubate in sealed flasks at room temperature for 4 weeks. Experiments were all performed in triplicate. Table 4-2 provides information on the incubation conditions for microbiological rerelease e xperiments performed under this project.

4.5.3.6 Mercury Analyses

The mercury collected in the traps designed to collect mercury released in the vapor phase was quantitated at the conclusion of each experiment . Hg analytical traps were analyzed as noted

in 4.4.1.7 above.

The leachate was separated from the sample in order to determine the concentrations of mercury in solution. Total mercury concentrati ons of the leachate were determined using

CVAFS or CVAAS.

In order to determine organomercury specie s of the mercury present in the leachates, SPME was used. SPME is a sample collection technique utilizing a fiber coated with polydimethylsiloxane. Samples containing orga nomercury compounds are first derivatized to increase the volatility of or ganomercury halides such as methylmercuric chloride. The derivitization reagents used were sodium tetraethyl borate, sodium tetrapropyl borate, and sodium tetraphenyl borate. Sodium tetraet hyl borate was most commonly used. In the derivitization procedur e, derivatizing agent, acetate buffer, an internal standard (usually propyl mercuric chloride), and sample were mixed in a septum-capped vial. In a relatively fast reaction, the halide is replaced with the appropriate alkyl or aryl group, dependi ng on which derivatizing agent is chosen. Five mL of the liquid plus an a liquot of ethylmercuric ch loride as an internal standard was placed into a 15-mL septum-capped nonactinic vial containing a Teflon-coated stir bar. 500 μL of a pH 4.5 acetate buffer was added fo llowed by 200 μL of a 1% solution of sodium tetrapropylborate. SPME sampling was accomp lished using a 100-μm polydimethylsiloxanecoated fiber and sampler from Supelco (Bellefo nte, Pennsylvania). An SPME fiber was inserted through the septum cap, and the sample was sti rred using a Teflon-coated stir bar for 20 min. After this equilibration time, the SPME fiber was introduced into the heated inlet zone of a GC. Sample separation can be accomplished using a 0.53-mm capillary column 15 or 30 m in length.24Table 4-2. Microbiological Experimental Incubation ConditionsExperimentNo.Number ofSamples Runin TriplicateApparatusUsed Acid Addition BufferAsh-to-BufferRatio Incubation Conditions1 1 OriginalapparatusNone Phosphate/nitrate buffer 50 gto 94 mL Anaerobic and aerobic bothwith glucose-fed andstarved conditions2 1 OriginalapparatusNone Phosphate/nitrate buffer 50 gto 100 mL Anaerobic and aerobic bothwith glucose-fed andstarved conditions3 1 OriginalapparatusPhosphoric acidadded to neutralizesolution pH toallow microbialgrowthPhosphate/nitrate buffer 80 g to 100 mL Anaerobic and aerobic bothwith glucose-fed andstarved conditions4 3 ModifiedapparatusSulfuric acid added toneutralize solutionpH to allowmicrobial growthPhosphate/glutamic acidbuffer20 g to 150 mL Anaerobic and aerobic withglucose-fed conditions5 3 ModifiedapparatusSulfuric acid added toneutralize solutionpH to allowmicrobial growth forfly ash samplesPhosphate/glutamic acidbuffer20 g to 150 mL Anaerobic and aerobic withglucose-fed conditions; nobacterial innoculum forFGD sample6 4 ModifiedapparatusSulfuric acid added toneutralize solutionpH to allowmicrobial growthPhosphate/glutamic acidbuffer18 g to 135 mL Anaerobic and aerobic withglucose-fed conditions25 The exit end of the column was connected to a heated quartz tube (800°C), and makeup helium gas was added to increase the total flow to be tween 25 and 30 mL per minute. The gas was then

routed to an AF detector for determin ation of the separated mercury compounds.

4.5.3.7 Microbiological Analysis

Bacterial counts were performed upon completi on of the experiments to determine if there were adequate active microbes present at the co mpletion of the experiment to account for any mercury releases found. A 1-mL aliquot of solution was taken from each flask. Prior to processing, the ash sample was stored in a flas k at 4°C. When processing, 100 μL was removed and added to 9.9 mL sodium pyrophosphate (PP) buffer (0.1% w/v) pH 7.0 with three glass beads in each test tube. This was vortexed for 30 s then serially diluted into PP buffer (up to 1/1000 dilution). These dilutions were used to inoculate a 3-tube most probable number (MPN) assay with 1% peptone–tryptone–yeast extract–glu cose (PTYG) buffer. Four mL of PTYG was placed in each 13 × 100-mm tube along with i nnoculum and incubated at room temperature. Tubes and plates (peptone–yeast extract–glucose [PYG] agar) inoculated with samples from the anaerobic ash suspension were incubated und er anaerobic conditions (anaerobic hood), and aerobic ash suspension samples were exposed to atmospheric oxygen. At week intervals, they were scored based on turbidity.

4.6 Field Investigations

The objective of this task was to develop information to facilitate an understanding of how laboratory results can be used effectively to determine potential releases of ATEs from CCBs in real-world management settings. Phase one of th is task included a field sampling event at a lignite-based power plant disposal facility. Follo wing assembly of the phase one results, project sponsors and researchers agreed that additional field measuremen ts would not be expected to yield adequate data to allow the development of a method that directly correlated laboratory data with field data, so an alternate laboratory ev aluation for measuring micr obiologically mediated Hg releases was designed as phase two of the task.

4.6.1 Field Task 1

Phase one of the field investigation was performed at CCB management facilities associated with a lignite-fired power plant. The field task cons isted of three key activities: 1) collection of near-surface solid samples and water samples where available, 2) mercury flux measurements taken at near-surface locations, and 3) collection of mercury samples from CCB

and fill air at near-surface loca tions. The EERC contracted with the University of Nevada–Reno (UNR) to perform the mercury flux measurements.

The EERC methodology for determining CCB landf ill air mercury levels was performed at several locations at the CCB management facility including a fly ash disposal site, a site where wet FGD material and mill rejects were codisp osed, a reclaimed fly ash landfill site, near a disposal pond containing wet FG D material and bottom ash, and n ear a disposal pond containing wet FGD material stabilized with fly ash. The me rcury-sampling sites are outlined in Table 4-3.26 Table 4-3. Mercury Measurement Site Descriptions Substrate Type Site Description Fly Ash Uncovered, fly ash landfill Vegetated Fly Ash with Soil

Cover Closed, reclaimed (vegetated) fly ash landfill with 2-ft clay cap and 3-ft soil cover

Wet FGD Material + Mill Rejects Uncovered disposal of mate rial from ash Pond 91 during

2003 Wet FGD Material (wet disposal) Wet disposal in the middle of the pond (unstabilized)

Bottom Ash/Mill Rejects + Wet FGD material (wet disposal) Wet disposal in the middle of the pond (unstabilized) surrounded by a bottom ash embankment

Stabilized Wet FGD Material (with fly ash) Uncovered HDPE 1 -lined facility (stabilized)

Natural Grasslands (background soil) Natural grassland

Agricultural land Agricultural land actively farmed

1 High-density polyethylene.

CCB landfill air was drawn through gold-coated quartz traps and tubes containing Supelco CarbotrapTM. The combination of collection on these two types of analytical traps allowed assessment of inorganic mercury (gold trap) an d organomercury species (Supelco CarbotrapTM). Traps were analyzed as noted in the laborat ory methods section of this report (4.4.1.7).

Solid samples and water samples were obtai ned for laboratory testing. Solid composite samples were taken of the substrate on which the mercury air sampling was conducted. Composite samples are described in Table 4-3. Li quid samples were collected at disposal ponds where possible. A map showing sampling locations is show n in Figure 4-11.

In situ mercury flux was measured by UNR re search staff using two field flux chambers linked to a total mercury analyzer (Tekran 2537A) systems. Mercury fluxes for the field chamber measurements were calculated using the Hg flux rate, outlet and inlet air Hg concentrations, airflow rate, and soil surface area covered by th e chamber. Chamber blanks were also obtained. This method has been successfully applied before at other fly ash site s (Gustin and Ladwig, 2004). Micrometeorological parameters were also measured during the same time frame as the

flux measurements. These included air and subs trate temperatures, relative humidity, and incident light. Several solid samples were collected at each field sampling location for determination of total mercury. For each material , fluxes were measured from at least three locations (Xin et al., 2006)

4.6.2 Alternate Field Task

The phase two field investigation (alternate fi eld task) was designed to evaluate the impact of interaction between soil and fly ash on merc ury release from fly as h. The interaction of greatest interest was that caused by inherent microbiological orga nisms typically found in soils. The CCB–soil laboratory experimental apparatus was designed to evaluate microbiologically27 Figure 4-11. Field sampling site map.

mediated mercury release from CCB–soil mixt ures, analogous to utilization management practices in the field. The experimental pr otocol was similar to the long-term ambienttemperature experiment and used a similar appara tus. A schematic of the apparatus is shown in Figure 4-12. Note that an inverted funnel was pl aced over the soil–ash bed to facilitate collection of released mercury.

A 20% addition of CCBs was combined wi th the soil and mixed thoroughly. The soil consisted of a mixture of topsoil, potting soil , and peat moss, which had moisture added to increase existing microbial activity. Approximate ly 200 grams of this mixture was placed in sample containers. Mercury-free air entered the sample container, swept over the sample, and exited through an inverted glass funnel. Or ganomercury compounds were captured on a collection trap containing Supelco Carbotra pTM, and elemental mercury was captured on goldcoated quartz. Six fly ash–soil mi xtures, one FGD material–soil mi xture, and soil alone were set up in duplicate.

After a period of mercury collection, the Supelco Carbot rapTM and gold-coated quartz analytical traps were analyzed for captured merc ury as noted previously. All sample containers were subjected to a blanking process to accoun t for elemental mercury present in the empty

container and the scrubbed air entering the system.

4.7 Data Reduction and Interpretation

The quality objectives of this effort s upport continued environmentally responsible management of CCBs and appropria te federal regulation of CCBs. The quality objective was to28 Figure 4-12. CCB–soil mercury vapor release collection apparatus.

select and/or modify experiment al methods that would be most appropriate for the material
types.

Because this was a laboratory project to eval uate mercury stability in CCBs, most of the analyses of the samples were done using stan dard EPA-approved laboratory methods. Other laboratory techniques that did not have speci fic EPA-approved methods were performed in accordance with standard EERC laboratory practice.

5.0 RESULTS AND DISCUSSION

5.1 Literature Search

The online database of literature gathered over the project duration, modeled after the EERC’s FIRST SEARCH database, is located on the Coal Ash Resource Center Web site at www.undeerc.org/carrc/mercury. A user name and password are required, which allows only project sponsors and researchers to access the database. The database can be quickly searched using the “Quick Search” tool or the “Advanced S earch” tool; it can be searched for a specific title, author, source/publisher, or abstract text. Users may also browse all publications in alphabetical order by title. The majority of public ations contain abstract text, and a method is provided to acquire the full text. In several instances, full text is provided free of charge by following the full text instructions. The database contained 526 documents. In addition to these documents being made available to project rese archers and sponsors, many of these documents29 were used in preparation of research status reports under a separate e ffort for the Canadian Electric Association, and those report s are included in Appendix C.

The literature assembled indicated the following:

• Most work in the area of mercury stability /release from CCBs has been published after

2004.

• The rerelease mechanism that has the most da ta available is that of direct leaching. Direct leaching evaluations have been pe rformed primarily on fly ash, with limited

activities on FGD materials. Several groups, including the EERC’s reports from this project, reported low mobility of mercury from fly ash due to leaching.

• The mechanisms of vapor-phase rerelease and microbiologically mediated leaching and vapor-phase rerelease were investigated since 2004 but the data report ed in the literature

were limited.

• Field-generated data were consistent with laboratory data even though only limited field investigations were report ed in the literature.

5.2 Analytical Methods Selection

The methods selected for use in this projec t are listed and described in the experimental section. For the most part, methods used were standard methods. Both ASTM and EPA methods

were used when available. Wher e required, exceptions to the use of standard methods were also described in the experimental section and in a re port prepared earlier in the project to summarize the analytical and release me thods selected. That report is included in Appendix D.

The leaching method selected, SGLP–LTL, was selected based on EERC experience and familiarity with a large number of leaching procedures used to characterize CCBs and the appropriate application of those tests. SGLP–LTL meets the criter ia that EERC researchers have identified for leaching procedures to provide scie ntifically valid information. These criteria are

as follows:

• Reactivity or other properties of the mate rial being leached that may influence the leaching profile.

• The setting where the material is to be placed and the water that will most likely contact that material in that setting.

• The leaching time required to allow adequate time for hydration reactions to occur in reactive materials, such as high-calcium coal fly ash.

The elevated-temperature vapor-phase re lease method, developed at the EERC in 1998 (Pavlish, 1999) underwent minor modifications early in the project as described in the experimental section of this report, but has been shown to provide reproducible data. The30 remaining technical challenge w ith the method as employed for th is project is the limitations

associated with the maximum achievable temperature to be a pplied to the CCB under investigation, and this cannot be addressed under this project. The method also has limitations for samples with high sulfur content because sulf ur compounds are released as a gas on sample exposure to elevated temperatures and are an interference to the dete rmination of mercury.

The ambient-temperature vapor-phase rel ease method developed fo r this work also presents technical challenges, but these are re lated to the quantitation limitations for mercury. The extremely low levels of merc ury released at ambient temper atures are frequently near the levels of detection for the analytical system be ing used. The physical nature of the CCB samples

also results in variable data and the need to modify the me thod. As an example, using the apparatus to evaluate the potential for release of mercury from a wet FGD material required modification of the apparatus to shorten the gas inlet tube to above the level of the sample because gas could not be forced through the materi al when the inlet was near the bottom of the sample container.

The EERC method developed to evaluate th e microbiologically mediated release of mercury underwent significant modi fications during the project. Fo r samples of low to moderate pH and low sulfur content, the apparatus no ted in Figure 4-10 was appropriate and allowed collection and analysis of merc ury released in the vapor phase and by leaching. For alkaline samples and those with high sulfur content, in cluding FGD materials, th e apparatus shown in Figure 4-12 was developed and used for determini ng the microbiologically mediated releases of mercury from CCBs by mixing the CCB sample with soil and introducing a low-mercury airstream. Analytical traps were used to capture organomercury and total mercury released as a vapor. This apparatus was used to complete the microbiological experiments, and because soil was used in the sample setup, these experiments al so served to complete the work for the field task, which had been modified as not ed in the experimental section.

5.3 Sample Identification and Selection

Sample selection was initiated by identifying samples that would potentially be available through government, industry, and marketing contact s. CCBs were selected from systems with conventional emission control technologies a nd advanced emission control technologies. Samples included 1) currently produced fly ash from a variety of coal sources and system configurations; 2) wet and dry FGD materials, focusing on proce sses with a higher probability for future installation; and 3) CCBs from pilot-scale or experimental emission control technologies with a high potential to be implem ented under existing or expected regulations. For activities related to experimental protocol and an alytical methods developm ent, high-mercury fly ash samples were used in order to allow meas urements of mercury above the lower level of quantitation (LLQ). These samples were select ed from systems producing fly ash with higherthan-average carbon content or, in some cases, t hose from fabric filter collection systems. The best choices for samples were those collected from full-scale combustion and FGD systems; however, these were not always available, especi ally for mercury control technologies and early in the project before large-sc ale DOE mercury emission control tests were initiated. Throughout the project, samples from systems with advanced emission controls were collected from system technologies in the research, development, and demonstration phases under DOE and other31 programs focused on emission control. Some sample s were collected from bench- or pilot-scale studies because those samples were th e only ones available at the time.

5.3.1 Sample Prioritization

A sample prioritization was performed as pa rt of the project kickoff meeting, and the results of that effort (included in Appendix E) pr ovided a target list of sample types to include in the project sample set. The highest-priority samples were identified to be those generated using the following:

• Bituminous, subbituminous, and lignite in pulve rized coal (pc)-fired units and fuel oil

• Fabric filter or ESP cold side • No FGD system or wet calcium-based FGD process or SDA. • No ammonia-based system or ammonia inject ion or selective catal ytic reduction (SCR).

High priority was also given to samples that could be collected from full-, pilot-, or benchscale systems for mercury em ission control as follows:

• Carbon injection • Noncarbon sorbent injection

• Modified FGD • Fine particulate control • Fly ash from carbon removal technologies

It was also noted that, where possible, sample s representing a “baseline” and “test” sample pair should be obtained. The project sample set included primarily samples identified as high priority. Samples generated from pc-fired systems using 100% bituminous, subbituminous, and lignite constituted the majority of the samples co llected for the effort. The majority of fly ash samples that were collected from demonstratio ns of mercury emission control systems had AC used as a sorbent. Only one paired set of fly ash samples was obtained from a fine particulate control system being tested for mercury cap ture. While no noncarbon-based sorbent samples were collected, one sample where a chemical “enhancing agent” was added was obtained and

evaluated.

A summary of samples finally selected for use in this project is include d in Tables 5-1–5-3. A complete listing of samples and the identifica tion information are included in Appendix F. Based on the sample quantity, qua lity, and relevance to the project, mercury and ATE release experiments were performed using these samples; however, not all samples were subjected to all types of release experiments, and some samples collected or submitted for the project were not included in the final sample sele ction. Reasons for excluding samp les from the selected sample set were the following:

• Insufficient sample to perform character ization analyses and release experiments • Insufficient sample identification information • Sample not representative of typical coal-based systems • Sample poorly taken or stored prior to receipt so integrity was in question32 Table 5-1. Summary of Fly Ash Samples and Fundamental Characterization Data

Coal Type No. of Fly Ash Samples No. of Fly Ash Samples from

Hg Control 24-hour pH Range LOI Range, % Total Hg

Concentration

Range, μg/g

Eastern

Bituminous 17 5.52–12.44 0.47–6.27 <0.01–0.685

6 with AC (postprimary PCD) 3.99–9.20 12.6–24.4 0.742–120

South American

Bituminous 2 9.13 12.7–21.2 0.151–0.607

2 with AC (preprimary PCD) NT 1 NT NT

Western

Bituminous 2 10.38–12.65 1.42–2.56 0.144–0.521

Subbituminous 3 12.27–12.56 0.32–1.08 0.261–1.224 with AC (preprimary PCD) 10.95–11.90 2.28–4.14 1.09–5.81

Lignite 13 10.50–12.74 0.22–7.48 <0.01–0.8784 with AC (preprimary PCD) 11.86–12.61 0.96–4.21 0.225–2.22

3 with EA 2 + AC (pre-primary PCD) 12.29–12.77 1.04–2.49 0.287–0.640

1 with EA 11.77 1.70 0.717

10 with AC (post-primary PCD) 10.52–12.00 0.59–13.2 0.147–64.5

1 Not tested.

2 Enhancing agent.

As noted, the sponsor sample prioritization proc ess indicated that an effort should be made to collect “paired” samples from full-scale demonstrations of mercury emission control technologies. These sample pairs included a base line sample (collected when the system was running with standard conditions and no mercur y emission control was imposed) and a test sample (collected during a mercury emission test). These samples were collected from the same location at a single site; however, the sample colle ction point and protocol varied between sites because of differences in the type of emission control and availability of sampling locations. Table 5-4 lists the paired sample sets, a brief description of th e mercury control technology used,

and fundamental characteristics of the samples. A total of eight pair ed sample sets were collected

and evaluated in various release experiments in the project.33 Table 5-2. Summary of FGD–SDA Samples and Fundamental Characterization Data

Coal Type No. of

FGD–SDA

Samples No. of FGD– SDA Samples from Hg

Control 24-hour pH Range LOI Range, % Total Hg

Concentration

Range, μg/g Lignite 3 12.50 0.95–12.5 <0.01–2.55

1 with EA + ACI (pre-SDA) 12.54 1.12 0.332

Subbituminous 1 12.22 2.07 0.105

Table 5-3. Summary of Eastern Bitumi nous Wet FGD Material Samples and

Fundamental Characterization Data

SO 2 Control No. of FGD Samples by Sample Type 24-hour pH Range LOI Range, % Total Hg

Concentration

Range, μg/g Wet Mg-

Enhanced Lime 2 FGD gypsum 7.75–7.88 1.22–1.92 0.032–0.044

Wet Limestone –

Forced Oxidation 3 FGD gypsum 7.72–7.95 1.60–2.26 0.043–0.103

Wet Limestone –

Nonoxidized 3 FGD filtercake 7.70–7.88 4.20–6.19 0.162–0.305

Wet Limestone –

Nonoxidized 3 Fixated FGD 10.50–12.43 3.11–4.17 0.136–0.249

5.3.2 Sample Handling

Fly ash as produced from full-scale coal-bas ed systems is generally considered to be homogeneous on the macroscale and heterogeneous on the microscale. This means that a sample of fly ash collected using appropriate compositi ng techniques will usually provide a high-quality, representative sample on which the bulk charac teristics can be determ ined with good accuracy. On the microscale, however, the individual particles will not necessarily reflect the bulk

characteristics of the material b ecause of the manner in which the individual particles are formed during the combustion process. FGD materials are generally considered homogeneous on both

the macro- and microscale.

For this project, the fly ash samples freque ntly were visually nonhomogeneous because of the presence of AC. Res earch staff frequently noted the pres ence of carbon as discreet particles within the fly ash sample matrix and also noted that the particle sizes of carbon present could be easily distinguished visually. On agitation of the glass sample c ontainers, the segregation of fly ash and carbon was also frequently noted. This obvious nonhomogeneity required increased care in obtaining analytical subsets of the bulk samples. Several appr oaches were used to ensure representative samples were used. Bulk samples were gently agitated, and the sample was34 Table 5-4. Paired Samples and Funda mental Characterization Data ID Nos. Sample Type 24-hour pH LOI, % Hg, μg/g 02-070 Fly ash 8.50 5.87 0.194 02-069 Fly ash + AC (post-primary PCD) 8.43 12.60 0.742 02-072 Fly ash 8.83 5.29 0.163 02-071 Fly ash + AC (post-primary PCD) 8.63 17.22 0.975 03-061 Fly ash 12.56 1.04 0.578 03-060 Fly ash + AC (pre-primary PCD) 11.90 2.38 1.86 04-035 Fly ash 12.74 2.46 0.159 04-036 Fly ash + EA + AC (pre-primary PCD) 12.77 2.33 0.287

05-001 Fly ash 12.51 0.90 <0.01 05-003 Fly ash + EA + ACI (pre-SDA) 12.29 1.04 0.565 05-005 Fly ash 11.57 1.29 0.431 05-017 Fly ash + EA 11.77 1.70 0.717 05-038 Fly ash 11.73 0.22 0.104 05-013 Fly ash + AC (post-primary PCD) 11.33 13.2 39.0 05-023 Fly ash + AC (pre-primary PCD) 12.00 3.84 12.7 05-024 Fly ash + AC (post-primary PCD) 11.41 9.45 35.9 05-025 Fly ash + AC (pre-primary PCD) 11.99 3.19 12.6 05-040 Fly ash + AC (post-primary PCD) 11.36 9.68 44.5 06-001 Fly ash + AC (post-primary PCD) 11.37 11.6 64.5 05-002 Fly ash + FGD–SDA 12.50 0.95 <0.0105-004 Fly ash + FGD–SDA + EA + AC (preSDA) 12.54 1.12 0.332

observed to get the carbon distribut ed representatively through the bulk sample container. For the total mercury and ATE analyses, duplicate samp les were used, and in some cases where the carbon content was especially problematic or the mercury content very low or very high, up to eight replicates were run. For the elevated-temperature releas e experiments, where only very small samples could be introduced into the experimental apparatus, samples with large carbon particles present were ground to produce a more homogeneous sample.

FGD material samples with water standing were dewatered for use in release experiments. This was done by pouring of the majority of water and filtering through a B h chner funnel or pressing the solid, depending on the experi ment the sample was to be used in.

5.3.3 Sample Descriptions

The samples selected for evaluation in this project were obtained from samples collected from bench-, pilot-, and full-scale combustion systems and from demonstration of multiple mercury emission control systems and types. In order to adequately describe the samples for the purpose of the discussion of the data and to draw conclusions while maintaining confidentiality of sample identity, the following sample descript ors were developed and are used throughout this
report.35 Fly ash – Fly ash sample that was generated under operating conditions that were not influenced by a mercury control technology. These samples may be generated in systems with NO

x , SO

x , or other emission controls, and the specific system type is noted in Appendix F.

Fly ash + AC (pre-primary PCD) – Fly ash that has AC present as a result of ACI for mercury emission control. The AC was injected before the primary PCD.

Fly ash + EA (EA on coal) + AC (pre-primary PCD) – Fly ash that has AC present as a result of ACI for mercury emission control and has a nother chemical that wa s also introduced to enhance mercury uptake by the fly ash + AC. The EA was added to the coal. The AC was injected before the primary PCD.

Fly ash + EA (EA on coal) – Fly ash that has a chemical that was introduced to enhance mercury uptake by the fly ash or to change the ox idation state of the mercury present to enhance mercury uptake in an existing FGD system. The EA was added to the coal.

Fly ash + AC (post-primary PCD) – Fly ash that has AC present as a result of ACI for mercury emission control. The AC was injected after the primary PCD and the fly ash + AC were collected in a secondary PCD. This type of sample would include samples produced in a TOXECONTM system. In this type of system, a portion of the fly ash would have already been removed by the primary PCD, so only a fraction of the total fly ash generated would be mixed

with AC.

FGD–SDA – An FGD material from a SDA confi guration. FGD–SDA uses a calcium-based sorbent (lime or hydrated lime) to remove SO 2 from the flue gas. Calcium sulfite and calcium sulfate are the primary pr oducts of the reaction of the sorbent and the SO 2 . In the United States (and in all project samples), fly ash is usually in corporated into the SDA system, so the solid byproduct contains a mixture of the calc ium sulfite and sulfate and fly ash.

FGD–SDA + EA (EA on c oal) + AC (pre-primary PCD) – An FGD material from a SDA configuration where EA was added to the coal and AC was injected ahead of the SDA.

Wet FGD material – Any material producted from wet fl ue gas scrubbing utilizing a calciumbased sorbent.

FGD gypsum – FGD material from a wet system employing forced oxidation, producing gypsum (ca SO 4 · 2H 2 O). The sorbent may be limestone or magnesium-enhanced lime, also called

dolomitic lime.

Wet FGD slurry – Material produced in a wet FGD syst em that uses inhibited oxidation or natural oxidation. It is typically a wet, thixotro pic material containing both calcium sulfite and calcium sulfate. It may also be refe rred to as “nonoxi dized” FGD material.

FGD filtercake – The resulting material after filtration of wet FGD slurry.36 Fixated wet FGD material – Wet FGD material that has a stab ilizing agent (typically fly ash) added to it to facilitate handling.

5.4 Chemical and Physical Characterization

The bulk chemical and physical characterization task focuse d on determining trace element composition, moisture content, LOI, pH, and ca rbon forms. Total major and minor constituents were also determined on a limited number of samples.

5.4.1 Total Mercury and ATEs

In order to adequately determine the releas e of mercury and other ATEs from fly ash and FGD materials, the total concentrations of thes e elements needed to be determined. The total trace element results for all samples evaluated are included in Appendi x G. The ranges for all samples (fly ash with and without mercury cont rol and all FGD material s) evaluated are as

follows:

• <1–492 μg/g arsenic • <1–8.59 μg/g cadmium • 2.90–160 μg/g chromium • <3–272 μg/g lead • <0.01–120 μg/g mercury • <1–277 μg/g nickel • <2–457 μg/g selenium

A more detailed summary of the ranges of to tal trace elemental concentrations in the fly ash, FGD–SDA samples, and wet FGD material samp les selected for this project are shown in Tables 5-5, 5-6, and 5-7, respectively.

Table 5-5. Range of Total Trace El ements in Fly Ash Samples, μg/g

Element Fly Ash Fly Ash + AC (pre-primary PCD) Fly Ash + EA+ AC (preprimary PCD) Fly Ash +

EA Fly Ash +AC (postprimary

PCD)

As 5.90–492 19.4–73.9 26.8–46.3 NT a 35.3–444

Cd <1–8.59 <1–1.97 <1–0.942 NT <1–3.38

Cr 43.4–160 39.1–111 44.8–49.1 NT 35.5–115

Pb 17.4–272 30.3–87.1 18.3–25.9 NT 49.0–85.3 Hg <0.01–1.22 0.225–12.7 0.287–0.640 0.717 0.147–120

Ni 17.2–277 18.6–67.6 23.1–41.5 NT 15.4–94.5

Se 3.97–44.7 13.4–69.4 9.86–18.3 NT 19.6–457

a Not tested.37 Table 5-6. Range of Total Trace Elements in FGD–SDA Samples, μg/g

Element FGD–SDA FGD–SDA + EA + AC (pre-primary PCD)

As 14.7–22.6 21.8

Cd <1 <1

Cr 26.3–42.8 37.3

Pb 18.6–37.0 20.9 Hg <0.01–2.55 0.332

Ni 12.9–29.7 25.3

Se 9.15–9.92 9.79

Table 5-7. Range of Total Trace Elements in Wet FGD Material Samples, μg/g

Element FGD Gypsum Wet FGD Slurry Wet FGD

Filtercake Fixated Wet

FGD Material

As <1–1.65 <1 <1 53.4–53.8

Cd <1–1.89 <1 <1 1.08–1.24

Cr 2.90–4.13 6.61 10.2–10.4 51.6–53.6

Pb <3 <3 <3–4.40 80.3–86.7 Hg 0.032–0.103 <0.1–0.196 0.162–0.305 0.136–0.249

Ni <1–6.83 2.87 3.50–3.98 87.2–98.7

Se <2–2.68 3.01 <2–2.64 3.71–4.46

For all elements except mercury and seleni um, the fly ash samples from mercury control tests were within the ranges of fly ash samp les without mercury control (Table 5-5). The concentrations of arsenic, cad mium, chromium, lead, and nickel measured in fly ash (without mercury control) selected for this project are al so consistent with the concentrations of these elements measured in fly ash samples from previous EERC projects (H assett and Heebink, 2002; Pflughoeft-Hassett et al., 2004, 1996).

Total mercury concentrations in the fly ash-based samples ranged as follows:

• Fly ash (without mercury control) – <0.01–0.878 μg/g • Fly ash + AC (pre-primary PCD collection) – 0.225–12.7 μg/g • Fly ash + AC (post-primary PCD collection) – 0.147–120 μg/g

In all cases where ACI was used, the total mercury concentration range was higher than that noted for fly ash samples, providing an in dication of increased me rcury capture on the fly ash + AC samples. The highest individual mercur y concentrations were noted for the fly ash + AC (post-primary PCD) category of fly ash samples.

Total selenium concentrations in the fly ash-based samples ranged as follows:

• Fly ash (without mercury control) – 3.97–44.7 μg/g • Fly ash + AC (pre-primary PCD collection) – 9.86–69.4 μg/g • Fly ash + AC (post-primary PCD collection) – 19.6–457 μg/g38 Similar to the mercury data, the total seleni um concentration range was higher for the fly ash + AC samples than the fly ash. Again, the hi ghest individual selenium concentrations were noted for the fly ash + AC (post-primar y PCD) category of fly ash samples.

Total concentrations of ATEs were determ ined in the FGD–SDA samples using the same analytical techniques as those used for the fly ash samples. Only a limited number of FGD–SDA samples were obtained for use in this project. Th e data in Table 5-6 represent two samples of FGD–SDA and one sample of FGD–SDA + EA + AC. The FGD–SDA + EA + AC had total

trace elemental concentrations that fell with in the range noted for the FGD–SDA samples

evaluated.

The total mercury concentration in FGD material samples was determined by DMA or

EPA Method 7471. Total concentrations of ATEs we re determined in the FGD material samples using the same analytical techniques as those us ed for the fly ash samples. A limited number of FGD materials from wet systems were collected fo r evaluation in this project. None of the wet FGD materials were collected from systems w ith mercury emission controls in use. Total mercury and ATE content ranges for each wet FGD material type are noted in Table 5-7. The ATE concentrations are generally similar fo r the wet FGD filtercake, slurry, and gypsum; however, several of the A TE concentrations are elevated in the fixated wet FGD material, most notably the arsenic, chromium, l ead, and nickel. It was hypothesized that the fly ash added to the

wet FGD material as a stabilizer resulted in these elevated ATE c oncentrations. No associated fly ash sample was available to conf irm or refute this hypothesis.

One FGD gypsum sample set was collected fr om a single plant with an SCR. One sample was collected when the SCR was on, and the s econd sample was collected when the SCR was off. However, these samples were not considered “paired” as the collection dates were 3 months apart, and it could not be ascertained if the coal source and other operating conditions were consistent between sample dates. The information for these samples is noted in Table 5-8.

Liquid from FGD samples was also analyzed for total trace elemental concentrations. These included FGD gypsum filtrate and la b-dewatered FGD liquor samples from FGD filtercake and FGD slurry. The ranges of total trace elemental concentrations are given in Table 5-9. All results are in Appendix H.

Table 5-8. Total Trace Elem ents in FGD Gypsum Samples Comparing SCR On and SCR Off, μg/g Element FGD Gypsum SCR On FGD Gypsum SCR Off

As 1.65 <2

Cd <1 <1

Cr 3.39 3.95

Pb <3 <3 Hg 0.043 0.103

Ni 6.83 6.81

Se 2.56 2.6839 Table 5-9. Range of Total Trace Elemen ts in FGD Liquor Samples, μg/L

Element FGD Gypsum

Filtrate Wet FGD Slurry Liquor Wet FGD Filtercake Liquor

As 82.8 114 33.1–121

Cd 4.79 0.790 2.09–4.34

Cr 9.90 10.1 2.90–5.70

Pb <2 <2 <2 Hg <0.01 <0.15 <0.15

Ni 338 258 88.8–333

Se 684 1140 154–759 pH 5.20 6.75 5.92–7.56

The total ATE concentrations were determined in these liquid samples in order to better

understand the distribution of A TEs in FGD systems. Mercury wa s undetected in all FGD liquid samples as expected based on previous work (Hassett and Moe, 1997). Arsenic, nickel, and selenium were present in the liquid samples in relatively high concentrations. Since no mercury

emission controls were in use while these sa mples were collected, it was not possible to

determine if the ATE concentrations for FGD liquids will be impacted by mercury emission

controls.

5.4.1.1 Paired Samples

Several sets of “paired” fly ash samples an d one set of FGD–SDA samples were collected and evaluated in this effort; the sample pair s and total mercury cont ent are presented in

Table 5-4. Total ATE content is noted for th ese paired fly ash samples in Table 5-10.

5.4.1.2 Total Mercury and ATE Discussion

Fly ash selected for this pr oject generally contained low co ncentrations of mercury (see Table 5-5), and total mercury c oncentrations were consistent with those reported elsewhere (Energy & Environmental Resear ch Center, 2004; Energy & Envi ronmental Research Center, 2005; Sanchez et al., 2006). Total mercury content of fly ash + AC, regardless of ACI point, had higher ranges of mercury. Paired fly ash sample s (Tables 5-4 and 5-10) clearly indicated that injection of AC does capture mercury, which results in elevated total mercury contents in the fly ash + AC samples as compared to the baseline fl y ash samples. Other ATEs measured in all fly ash samples were generally present at similar co ncentrations regardless of whether the samples were collected with or without mercury emission controls in place.

For all FGD–SDA samples, the total conc entrations of individual ATEs, including mercury, were similar for those with and w ithout mercury emission controls in place.

The wet FGD material samples generally had lower total ATE concentrations than the fly ash and FGD–SDA samples, with the exception of the fixated wet FGD material. The

concentrations of most ATEs we re higher in those samples than the other wet FGD materials, likely because of added fly ash that was used for the fixation process.40 Table 5-10. Paired Samples and Total ATE Content, μg/g ID Nos. Sample Type As Cd Cr Pb Hg Ni Se 03-061 Fly ash 43.5 1.72 67.6 59.5 0.578 93.9 44.5 03-060 Fly ash + AC (pre-primary PCD) 19.4 1.87 76.7 82.2 1.86 67.6 34.2

04-035 Fly ash 36.0 <1 55.4 21.9 0.159 17.2 9.7804-036 Fly ash + EA + AC (preprimary PCD) 44.9 <1 48.8 18.7 0.287 23.5 10.4

05-001 Fly ash 24.4 <1 45.1 17.4 <0.01 30.3 8.8405-003 Fly ash + EA + AC (preSDA) 28.6 <1 45.5 21.2 0.565 25.7 11.5

05-038 Fly ash 43.4 <1 43.4 90.1 0.104 21.1 23.4 05-013 Fly ash + AC (post-primary PCD) 38.6 <1 36.5 73.2 39.0 15.4 60.3

05-023 Fly ash + AC (post-primary PCD: high fly ash) 48.3 <1 42.6 87.1 12.7 18.6 22.5

05-024 Fly ash + AC (post-primary PCD) 42.5 <1 35.5 82.2 35.9 17.6 87.3

05-025 Fly ash + AC (post-primary PCD: high fly ash) 46.8 <1 39.1 84.7 12.6 20.4 30.1

05-040 Fly ash + AC (post-primary PCD) 38.4 <1 42.2 74.5 44.5 22.0 42.2

06-001 Fly ash + AC (post-primary PCD) 35.5 <1 39.8 72.0 64.5 20.6 38.9

05-002 Fly ash + FGD–SDA 22.6 <1 42.8 18.6 <0.01 29.7 9.15 05-004 Fly ash + FGD–SDA + EA + AC (pre-SDA) 21.8 <1 37.3 20.9 0.332 25.3 9.79

Review of the total ATE concentrations for the paired samples indicated that most ATE concentrations remained consistent between pair ed samples. Mercury was the only ATE that was consistently elevated in the test samples as compared to the baseline sample. A significant

increase was noted in the total selenium concen tration in fly ash + AC (post-primary PCD) over the baseline and fly ash + AC (pre-p rimary PCD) in one sample set.

5.4.2 Total Bulk Chemical Composition

A limited number of samples were analyzed for total bulk chemical composition early in the project. The major and minor elements dete rmined were silicon, al uminum, iron, calcium, magnesium, sodium, potassium, barium, manganese , titanium, phosphorus, strontium, and sulfur. The results of these analyses, reported as oxides as is convention with fly ash, are included in Appendix I. The data are summarized in Ta ble 5-11, which also includes the ASTM C618 specification for fly ash for use as a mineral admixture in concrete.41 Table 5-11. Summary of Total Bulk Chemic al Composition Compared to ASTM C618 Specifications, %

Parameter Fly Ash Fly Ash + AC (pre-primary PCD) FGD–SDA FGD Gypsum ASTM C618 Class F Fly Ash

Specifications ASTM C618 Class C Fly Ash

Specifications

SiO 2 +
Al 2 O 3 +

Fe 2 O 3 46.76–

92.25 53.57–63.29 52.02 0.47 70 min. 50 min.

SO 3 0.06–

4.73 1.43–5.89 13.60 51.14 5.0 max. 5.0 max.

Moisture

Content 0.01–

0.14 0.05–0.23 1.01 17.37 3.0 max. 3.0 max.

LOI 0.32–

4.25 0.91–4.22 1.49 12.68 6.0 max. 6.0 max.

The sample set included five samples of bitu minous fly ash, one samp le of lignite fly ash, four samples of lignite fly ash + AC (pre-p rimary PCD), one subbituminous fly ash, and one subbituminous fly ash +AC (pre-primary PCD). Th e sample set also included one sample of FGD gypsum and one sample of FGD–SDA. Initiall y, it was proposed that these analyses would be valuable in data interpretation because th ey would provide information on the potential utilization options (mineral admixture for concrete, raw feed for cement kiln, cementitious applications, etc.) for the samples collected. The fly ash data shown in Table 5-11 indicated that the limited samples evaluated were typical of sa mples used as mineral admixtures for concrete, and even the samples with added AC met th e specification for LOI in ASTM C618. It was determined that the LOI and chemistry of fly ash samples were not adequate to provide an indication of utilization performance, so this task was not providing the type of information anticipated. Further, it became apparent that many of the samples selected for release experiments in this project were not collected from locations typical of “as managed” samples that are usually evaluated for ut ilization potential. A decision was made with agreement from project sponsors to discontinue th is subtask for those reasons.

5.4.3 LOI and Moisture Content

The moisture content and LOI of solid CCBs were determined. Ranges of moisture content and LOI are presented in Tabl es 5-12 through 5-14. Moisture c ontent and LOI results for all samples evaluated are included in Appendix J. As noted in Table 5-12, fly ash from mercury control technology testing had LOI values ranging from 0.59% to 24.4%. Fly ash without mercury control had LOI ranging from 0.22% to 21.2%.

Table 5-12. Range of Moisture Content and LOI in Fly Ash Samples, %

Parameter Fly Ash Fly Ash + AC (preprimary PCD) Fly Ash + EA+ AC (preprimary PCD) Fly Ash + EA Fly Ash + AC (post-primary PCD)

Moisture

Content 0.02–1.00 0.00–1.07 0.05–0.85 0.05 0.10–5.56

LOI 0.22–21.2 0.96–4.21 1.04–2.49 1.70 0.59–24.442 Table 5-13. Range of Moisture Content and LOI in FGD–SDA Samples, %

Parameter FGD–SDA FGD–SDA + EA + AC (preprimary PCD)

Moisture Content 1.08–3.00 0.75

LOI 0.95–12.5 1.12

Table 5-14. Range of Moisture Content and LOI in FGD Material Solid Samples, % FGD Material Type Moisture Content LOI FGD Gypsum 21.6–26.7 1.22–2.26 Wet FGD Slurry 56.8–65.7 4.37–6.38

Wet FGD Filtercake 28.6–43.3 4.20–6.19

Fixated Wet FGD 26.6–31.9 3.11–4.17

Moisture content and LOI for the paired fl y ash and FGD–SDA samples selected for this project are shown in Table 5-15. LOI increased for all but one sample pair with the injection of AC. The largest increases in moisture content and LOI from the fly ash to the paired samples were noted in the fly ash + ACI (post-primary PCD) samples. The fly ash + ACI (post-primary PCD: high ash) samples in the largest paired sample set showed increased LOI values over the fly ash but were minimal compared to the ot her fly ash + ACI (post-primary PCD) samples within the sample set. The fly ash and FGD–SD A samples containing an enhancing agent on the coal in the mercury control tec hnology testing generally showed the least ch ange in moisture

content and LOI.

Moisture content and LOI data for FGD–SDA sa mples selected for this project are noted in Table 5-13. For FGD–SDA samples, the LOI is likel y dependent on the LOI of the fly ash that is incorporated into the FGD–SDA final by-product ma terial. Most frequentl y, fly ash incorporated into FGD–SDA material is alkaline and provides some sorptive capacity for SO 2 capture. It is also generally true that alka line fly ash tends to have lowe r LOI than nonalkaline fly ash; however, as noted in the data in Table 5-13, a relatively high LO I value of 12.5% was measured in one FGD–SDA sample. Since no paired fly as h sample was available for testing, it is not known if this high LOI value is du e to carbon present in the inco rporated fly ash or is due to dehydration of hydrated phases pr esent in FGD–SDA. FGD–SDA us ually comprises relatively high percentages of calciu m sulfite hemihydrate (CaSO 3 ·1⁄2H 2 O, or hannebachite), which will lose water of hydration as well as SO 2 at temperatures above 600°C. Since LOI determinations are carried out at 750°C, the valu es reported will be indicative of these losses as well as any carbon that may be in the sample.

Table 5-14 shows the data on moisture conten t and LOI for a variety of wet FGD materials selected for use in this project. The moisture co ntent values reflect the water typically present in wet FGD materials. With the exception of FGD g ypsum, the types of wet FGD materials noted in Table 5-14 comprise calcium sulfit e and sulfate phases an d, prior to filtering or fixation, are a thixotropic material with high water content and problematic ha ndling properties. Even after43 Table 5-15. Paired Samples Moisture Content and LOI, % ID Nos. Sample Type Moisture Content LOI 02-070 Fly ash 0.20 5.87 02-069 Fly ash + AC (post-primary PCD) 0.78 12.6 02-072 Fly ash 0.17 5.29 02-071 Fly ash + AC (post-primary PCD) 1.18 17.2 03-061 Fly ash 0.17 1.04 03-060 Fly ash + AC (pre-primary PCD) 0.17 2.38 04-035 Fly ash 0.14 2.46 04-036 Fly ash + EA + AC (pre-primary PCD) 0.06 2.33

05-001 Fly ash 1.00 0.90 05-003 Fly ash + EA + AC (pre-SDA) 0.85 1.04 05-005 Fly ash 0.02 1.29 05-017 Fly ash + EA 0.05 1.70 05-038 Fly ash 0.04 0.22 05-013 Fly ash + AC (post-primary PCD) 0.29 13.2 05-023 Fly ash + AC (post-primary PCD: high ash) 0.13 3.84

05-024 Fly ash + AC (post-primary PCD) 0.23 9.45 05-025 Fly ash + AC (post-primary PCD: high ash) 0.07 3.19

05-040 Fly ash + AC (post-primary PCD) 0.10 9.68 06-001 Fly ash + AC (post-primary PCD) 0.39 11.6

05-002 FGD–SDA 1.08 0.95 05-004 FGD–SDA + EA + AC (pre-SDA) 0.75 1.12

filtering or fixation, a significant level of moisture is maintained. The LOI is likely a result of loss of water of hydration or, in the case of the fixated FGD mate rial, unburned carbon in the fly ash used as the fixation agent may contribute to the LOI.

FGD gypsum (calcium sulfate·2H 2 O), generally 95+% pure, exhibits lower moisture content because it is more readily separated from the water phase because of its crystalline form. The LOI for FGD gypsum is likely due to loss of water.

5.4.3.1 pH

The pH of all samples of sufficient quantit y was determined in distilled water with a 10– 15-minute equilibration time. Previous experience with fly ash and pH measurement raised questions about the most appr opriate method to determine pH of CCBs. Since the pH of a material can influence the leaching profile and may impact the performance in certain utilization scenarios, including bulk placement in engineered fills, it is important to determine the pH as accurately as possible, even though the pH may change with time. It was decided to perform additional pH measurements including 24-hour (d istilled water) pH and 10–15-minute pH using44 1 M KCl (potassium chloride). All pH data collected on project samples are included in Appendix K.

Table 5-16 separates the pH va lues for all fly ash samples by co al type and pH test. Eastern bituminous fly ash samples exhibited a wide range of pH values in all tests. This range was greater in the fly ash samples without AC th an with AC. The South American and western bituminous fly ash sample pH ranges were narro wer and were closer to those of subbituminous and lignite fly ash samples than eastern bitumi nous fly ash samples. All fly ash + ACI (preprimary PCD) pH values, for the South Am erican bituminous, subbituminous, and lignite samples in the project, were similar. The pH of all types of lignite fly ash samples were similar; however, the fly ash + AC (post-primary PCD) samples had pH values below 10 reported. The high-ash samples in the lignite fly ash + AC (post-primary PCD) exhibited the highest 24-hour pH values in that sample set. Overall, th e difference between the 10–15-min and 24-hour pH tests is not significant but can be seen on a per-sample basis.

Some samples exhibited a near-neutral 10–15-mi nute pH, but after 24 ho urs of stirring, the pH increased to an alkaline value. During this equilibration time, the samples were stirred at 350 rpm. As stated above, numerous samples e xhibited pH values that changed substantially

after 24 hours. Table 5-17 shows th e sample information for these samples and the associated

LOI.

Table 5-16. Range of pH in Fly Ash Samples

Coal Type pH Test Fly Ash Fly Ash +AC (preprimary

PCD) Fly Ash + EA+ AC (preprimary PCD) Fly Ash +

EA Fly Ash +AC (postprimary

PCD)

Eastern

Bituminous 10–15-min 3.76–12.56 NA NA NA 3.47–9.59

24-hour 5.52–12.44 NA NA NA 3.99–9.20

1 M KCl 4.42–12.72 NA NA NA 3.51–9.43

South

American

Bituminous 10–15-min 9.93–11.72 10.34–11.79 NA NA NA

24-hour 9.13 NT NA NA NA

1 M KCl 10.66 NT NA NA NA

Western

Bituminous 10–15-min 11.52–13.00 NA NA NA NA

24-hour 10.38–12.65 NA NA NA NA

1 M KCl 11.40–12.83 NA NA NA NA

Subbituminous 10–15-min 11.89–12.56 10.65–11.47 NA NA NA

24-hour 12.27–12.56 10.95–11.90 NA NA NA

1 M KCl 11.96–12.62 10.48–11.16 NA NA NA Lignite 10–15-min 11.20–12.84 11.74–12.69 12.39–12.85 12.04–12.19 6.69–11.67

24-hour 10.50–12.74 11.86–12.61 12.29–12.77 11.77 10.52–12.00

1 M KCl 11.05–12.84 12.38–12.84 12.82 NT 9.42–11.7345 Table 5-17. Fly Ash Samples Exhibiting a Greater-than-One-pH-Unit Change

over a 24-hour Period

ID No. Sample Type Coal Type 10–15- min pH 24-hr pH pH Change LOI, %05-040 Fly ash + AC (postprimary PCD) Lignite 7.03 11.36 4.33 9.68

03-083 Fly ash Eastern

bituminous 4.75 9.00 4.25 1.20

06-001 Fly ash + AC (postprimary PCD) Lignite 7.20 11.37 4.17 11.62

05-024 Fly ash + AC (postprimary PCD) Lignite 7.43 11.41 3.98 9.45

03-004 Fly ash Eastern

bituminous 4.54 7.08 2.54 3.34

05-013 Fly ash + AC (postprimary PCD) Lignite 9.00 11.33 2.33 13.24

03-006 Fly ash Eastern

bituminous 4.82 6.78 1.96 5.24

03-005 Fly ash Eastern

bituminous 4.45 5.88 1.43 3.60

03-007 Fly ash Eastern

bituminous 4.38 5.52 1.14 4.48

05-018 Fly ash Eastern

bituminous 7.42 8.49 1.07 3.01

04-006 Fly ash Western

bituminous 11.56 10.38

− 1.18 1.42

02-076 Fly ash South

American

bituminous 10.38 9.13

− 1.25 21.06

02-072 Fly ash Eastern

bituminous 10.09 8.83

− 1.26 5.29

02-070 Fly ash Eastern

bituminous 9.98 8.50

− 1.48 5.87

The fly ash samples that exhibited an increase in pH from the 10–15-minute measurement to the 24-hour measurement were either bituminous or lignite samples, but the lignite samples all contained AC from injection after the primary PC D and an associated relatively high LOI. The 10–15-minute pH for the lignite fly ash + AC sample s was 7 or higher, and the increase in pH at 24 hours ranged from 2.3 to 4.3 units. The bitu minous fly ash samples had 10–15-minute pH values of ~4.4–7.4 and had LOI values of 1.2%–5.2%. Most of these samples exhibited a pH increase of ~1–2 units; however, the sample with the lowest LOI (1.2%) had an increase of over 4 units. For the lignite fly ash + AC samples, th e reason for the increases noted was not evident but may be associated with the AC present, hydr ation reactions, or solubility of surface coatings or specific phases in the sample.46 Four bituminous fly ash samples exhibite d a decrease in pH from the 10–15-minute

measurement to the 24-hour measurement. Solubili ty of specific phases or coatings or hydration reactions may also have an impact on these samp les and cause changes to the pH. This decrease could also be due to uptake of CO 2 from the atmosphere.

These pH development data are interesting beca use pH is a primary factor in leachability. It has been shown that at pH values over 10.5, e ttringite can and will form in fly ash samples. This is important because of the fact that ettr ingite can incorporate numerous oxyanions such as borate, chromate, and selenate into its structure, thus rendering them insoluble. It is important, especially with alkaline ash types, to know the true equi librium pH in order to decide if LTL is necessary. LTL is always suggested at 18-hour and 30- and 60-day equili bration times in ash samples with equilibrium pH values above 10.5. Th e only exception to this is if mercury is the only analyte. Mercury does not appear to be aff ected by ettringite formation. These data suggest that pH measurements for CCBs should include an equilibration time of at least 24 hours.

The pH values reported for all FGD–SDA samp les (Table 5-18) fell within a narrow range regardless of the presence of AC. The pH for thes e samples is primarily a result of the presence of unreacted sorbent, which is present as ca lcium hydroxide. Calcium hydroxide has a pH of 12.4, which is very similar to the pH values m easured in the FGD–SDA samples. The presence of alkaline fly ash may also influence the pH of FGD–SDA samples, but the lack of a separate fly ash sample from these systems does not allow a discussion of the impact of the fly ash on pH. The pH of the FGD–SDA +EA + AC samples is s lightly elevated from the FGD–SDA samples. It was hypothesized that the increas ed pH, while minimal, could be associated with the presence of AC or the EA, which was unidentified.

The ranges of pH values of FGD materials and liquids are shown in Tables 5-19 and 5-20 and Appendices H and K. With the exception of the fixated wet FGD materials, the wet FGD materials and liquids all exhibite d acidic to near-neutral pH. This is due to either complete reaction of the alkaline scrubbing material or coating of the alka line phase with neutral calcium sulfate. The fixated wet FGD material likely exhi bits an alkaline pH because of the presence of fly ash used to fixate the material.

Table 5-18. Range of pH in FGD–SDA Samples Coal Type pH Test FGD–SDA FGD–SDA + EA + AC

Subbituminous 10–15-min 12.34–12.41 NA

24-hour 12.22 NA

1 M KCl 12.53 NA Lignite 10–15-min 12.18–12.85 12.51–13.06

24-hour 12.50 12.54

1 M KCl NT NT47 Table 5-19. Ranges of pH in Wet FGD Material Sample FGD Gypsum Wet FGD Slurry Wet FGD Filtercake Fixated Wet FGD 10–15-min pH 8.07–8.83 7.84–8.95 7.47–8.18 10.87–12.75 24-hour pH 7.72–7.95 8.75 7.70–7.88 10.50–12.43 1 M KCl pH NT NT NT 11.75–12.30

Table 5-20. Ranges of pH in Li quid from Wet FGD Material Samples FGD Gypsum

Filtrate FGD Slurry Liquor FGD Filtercake Liquor FGD Filtrate 10–15-min pH 5.40–5.49 6.73–6.78 6.53–7.36 7.20–7.26 24-hour pH 5.20–5.25 7.38 5.92–7.56 8.13–8.17

5.4.4 Carbon Forms

It is well known that unburned carbon associated with co al fly ash takes on many different morphological forms, three major forms of which are generally recognized. These morphologically different carbon forms are inertinite , isotropic coke, and anisotropic coke. Each of these forms has distinct and predictable physi cal properties. Isotropic and anisotropic coke have gone through the combustion process and undergone considerable changes including melting and reaction with oxygen, while inertinite appears to be relatively unaffected by the combustion process. Isotropic cokes represen t extensively reacted, nongraphitizable carbon particles, and anisotropic cokes represent ex tensively reacted, more highly aligned carbon particles (Maroto-Valer et al., 1999a). In a study of carbon forms associated with Class F fly ash,

it was found that inertinites exhibi t the lowest surface area (15–25 m 2 /g), isotropic coke particles presented intermediate surface areas (25–35 m 2 /g), and anisotropic coke exhibited the highest surface areas (35–60 m 2 /g) (Maroto-Valer et al., 1999b). Ther efore, inertinites represent lowdensity, low-surface-area particles; isotropic coke s represent intermediate-density, intermediatesurface-area particles; and anisot ropic cokes represent high-density , high-surface-area particles. Studies on Class C fly ashes, ge nerally derived from subbitumi nous and lignite coals, have shown much higher surface areas (200–400 m 2 /g) (Maroto-Valer et al., 1999b), indicating that the properties of fly ashes are not only depende nt on petrographic compos ition, but also on the rank of coal from which they are derived (Marot o-Valer et al., 1999b). Proba bly, in part, due to the differences in surface area, the adsorption of mercury has shown the same series with anisotropic coke > isotropic coke > inertinite.

A limited number of fly ash samples were analyzed to determine carbon forms present (Appendix L). A summary of the data collected is shown in Table 5-21, incl uding the types of fly ash samples evaluated, the identified dominan t carbon forms, and the mercury content of the samples.

As indicated by the data in Table 5-21, fl y ash samples without any AC present had a broad range of LOI, which generally reflec ts the amount of unburned carbon present. While other chemical changes can contribute to LOI, th ese are usually small cont ributions. The results48 Table 5-21. Number of Samples per Carbon Form with Total Hg and LOI Ranges

Fly Ash Fly Ash + AC (Pre-Primary PCD) Fly Ash + AC (Post-Primary PCD)

Dominant

Carbon

Form No. Samples Hg Range, μg/g LOI Range, % No. Samples Hg Range, μg/g LOI range, % No. Samples Hg Range,

μg/g LOI Range, % Anisotropic

Coke 2 0.607–0.785 2.54–21.2 2 0.289–1.86 0.97–2.47 2 55.6–120 22.2–24.4

Isotropic

Coke 2 0.440–0.578 1.00–7.48 1 1.09 2.84 0 NA NA

Inertinite 1 0.097 3.20–3.48 2 0.225–2.22 0.96–4.21 0 NA NA

Vitrinite 4 <0.01–0.662 0.24–4.54 0 NA NA 0 NA NA

Unburned

Carbon 5 0.017–0.197 1.20–12.7 1 0.490 1.26–1.29 0 NA NA

indicated that unburned car bon was the dominant carbon form in most of these samples, with the second most prominent form of carbon present be ing vitrinite, another relatively low-sorbing carbon form. The fly ash samples from systems w ithout AC addition also contained the lowest concentrations of mercury, and those with unbur ned carbon, vitrinite, and inertinite as the dominant carbon form generally had the lowest mercury content within that sample’s set.

Very limited samples of fly ash with AC (fly ash + AC [pre-primary PCD]) and fly ash + AC [post-primary PCD]) were available for an alyses; however, the data indicate that these samples contain more reactive carbon forms. Th e two samples of fly ash + AC (post-primary PCD) evaluated both had anisotropic coke as the dominant carbon form. The LOI of these samples was very high as was the mercury content, which is consistent with the presence of a high-sorbing carbon form. For the fly ash + AC (pre -primary PCD) samples, three of six samples evaluated had either anisotropi c or isotropic coke as the do minant carbon form. The LOI and mercury contents of these samples were similar to the four samples of fly ash without mercury control that had anisotropic and isotropi c carbon as the dominant carbon forms.

The carbon form data verify that the pres ence of high-sorbing carbon forms can be an indicator of elevated mercury in fly ash samples and that AC contains these high-sorbing carbon

forms.

5.5 Laboratory Evaluation of ATE Releases

5.5.1 Direct Leaching

Leaching was performed using multiple tests. As already noted, the methods were TCLP (EPA Method 1311, 1992), SGLP, and LTL with 30- and 60-day equilibration periods. Mercury and other ATEs were determined on leachates as the sample quantity allowed. Complete leachate data are reported in Appendix M. Summaries of leachate data are shown by sample type in Tables 5-22 through 5-24.49 Table 5-22. Ranges of Leachate Results for Fly Ash, μg/L

Element Fly Ash Fly Ash + AC (pre-primary PCD) Fly Ash + EA + AC (pre-primary PCD) Fly Ash + EA Fly Ash + AC (post-primary PCD)

As <2–336 <2–16.3 <2–15.2 46.3–95.9 8.1–842

Cd <0.2–8.30 <0.2–1.49 <0.2–0.39 <0.3–2.68 0.85–2.46

Cr 1.40–277 3.60–560 <2–134 182–211 17.3–680

Pb <0.001–8.50 <0.001–3.00 <0.001–3.00 <2 <2 Hg <0.01–0.325 <0.01–0.068 <0.01–0.061 <0.01–0.02 <0.01–0.07

Ni <2–80.6 <2–23.1 <2–25.2 <2–2.8 <2–23.4

Se <2–514 <2–147 <2–47.2 <4–97.0 45.2–8620 pH 3.54–12.81 3.80–12.60 12.21–12.61 11.69–12.01 3.79–11.82

Table 5-23. Ranges Leachate Results for FGD–SDA, μg/L

Element FGD–SDA FGD–SDA + EA + AC (preprimary PCD)

As 2.1–3.5 3.6–4.3

Cd <0.2–0.59 <0.2–0.2

Cr 34.6–223 21.8–87.7

Pb <2 <2 Hg <0.01–0.095 <0.01–0.012

Ni <2–39.1 <2–29.3

Se 11.3–65.8 12.0–24.3 pH 11.41–12.47 12.41–12.60

Table 5-24. Ranges of Leachate Results for Wet FGD Material, μg/L

Element FGD Gypsum Wet FGD Slurry Wet FGD

Filtercake Fixated Wet

FGD

As <4 <4 <2–3.7 <2–24.0

Cd <0.2–0.46 <0.3 <0.2–0.830 0.30–0.66

Cr <2 <1 <2 2.2–4.7

Pb <2 <0.001 <2 <2–14.3 Hg <0.01 0.047 <0.01–0.476 <0.01–0.289

Ni <2–28.4 15.0 6.10–32.1 <2–4.00

Se 2.70–18.7 65.0 41.0–71.2 <2–3.40 pH 7.42–8.17 8.02 7.57–8.39 11.31–12.34

A leaching topical report was published in August 2005 and can be found in Appendix N. Leaching experiments continued after the leachi ng topical report was published, but the added data were consistent with those presented in the topical report and supported the observations

made. The results for each element included in th e study are presented and di scussed in detail in the following sections.50 5.5.1.1 Mercury

Mercury leachate results fo r fly ash, FGD–SDA, and FGD material samples are reported on separately. Total mercury concentrations di scussed throughout the se ction are included in Appendix G.

The ranges of mercury leachate results for fly ash are reported by leaching test in

Table 5-25. Table 5-26 shows that data separated by coal type . Figure 5-1 shows the 18-hour SGLP mercury leaching data for fly ash samples pl otted against the total mercury content of the sample. Figure 5-2 shows the 18-hour SGLP mercur y leaching data for fly ash + AC and/or EA samples plotted against the total mercury content of the sample.

For fly ash and fly ash + AC and/or EA, me rcury is not readily leachable. Most samples have a leachate concentration below the 0.01 μg/L analytical method reporting limit. All fly ash sample leachates had mercury concentrations below the 2.0-μg/L primary drinking water (PDW) limit. The graphical representations of the merc ury leachate data for fly ash and fly ash + AC and/or EA samples, as shown in Figures 5-1 an d 5-2, also indicated that total mercury content does not correlate with leachable mercury. This is true for all leaching methods used in this project. The leachability of mercury from fly ash is not expected to impact current fly ash management practices.

Review of the total mercury content and leac hate concentrations fo r the paired fly ash samples indicated that the tota l mercury concentration increase d with the introduction of AC (with or without an EA) regardless of the locati on where the AC was injected (see Tables 5-27– 5-29). The total mercury concentrations of fl y ash + AC collected from post-primary PCD locations showed the greatest incr ease over the concentrations measured in the baseline fly ash samples. The mercury leachate concentrations reported for the paired fly ash samples do not reflect the increased total mercury content, and the mercury leachate concentrations are similar for all fly ash samples within the paired sample set for all leaching procedures, time frames, and final leachate pH. Most fly ash samples, both th e paired sample set a nd the overall project sample set, had mercury leachate results of <0.01, the analytical reporting limit of the method used. The total mercury content does not correl ate with the mercury l eachate concentrations.

Table 5-25. Ranges of Fly Ash Mercury Leac hate Results by Leaching Test, μg/L

Test Fly Ash Fly Ash + AC (pre-primary PCD) Fly Ash + EA + AC (pre-primary PCD) Fly Ash + EA Fly Ash + AC (post-primary PCD)

18-hour

SGLP <0.01–0.083 <0.01–0.064 <0.01–0.016 <0.01 <0.01–0.03

30-day

LTL <0.01–0.113 <0.01 <0.01–0.061 <0.01 <0.01

60-day

LTL <0.01–0.325 <0.01–0.068 <0.01–0.016 <0.01–0.02 <0.01–0.028

TCLP <0.01–0.034 <0.01 NT NT <0.01–0.07051 Table 5-26. Ranges of Fly Ash Mercury Leachate and Leachate pH Results by Coal Type and Leaching Test

Coal Type Sample Type TCLP Hg

Leachate and pH 18-hour SGLP Hg Leachate and pH 30-day LTL Hg Leachate and pH 60-day LTL Hg Leachate and pH

Eastern

Bituminous Fly ash <0.01–0.03 μg/L

3.54–4.97 <0.01–0.05 μg/L

4.71–12.67 <0.01–0.104 μg/L

9.38–11.49 <0.01–0.239 μg/L

5.55–11.36

Eastern

Bituminous Fly ash + AC (post-primary PCD) <0.01–0.07 μg/L

3.79–4.76 <0.01–0.03 μg/L

4.00–9.89 NT NT

South

American

Bituminous Fly ash <0.01–0.034 μg/L

3.89–4.11 <0.01–0.016 μg/L

11.18–11.68 NT NT

South

American

Bituminous Fly ash + AC (pre-primary PCD) <0.01 μg/L

3.80–4.20 <0.01 μg/L

10.71–11.71 NT NT

Western

Bituminous Fly ash NT <0.01–0.021 μg/L

11.59–12.81 0.035–0.076 μg/L

11.37–12.54 <0.01–0.087 μg/L

11.31–12.52

Sub-

bituminous Fly ash NT <0.01–0.023 μg/L

12.09–12.49 <0.01 μg/L

12.36–12.63 <0.01–0.325 μg/L

12.45–12.58

Sub-

bituminous Fly ash + AC (pre-primary PCD) <0.01 μg/L

5.51–6.56 <0.01–0.064 μg/L

11.08–12.21 <0.01 μg/L

11.84–12.46 <0.01–0.068 μg/L

11.85–12.38 Lignite Fly ash NT <0.01–0.083 μg/L

10.95–12.60 <0.01–0.113 μg/L

11.34–12.65 <0.01–0.124 μg/L

11.25–12.54 Lignite Fly ash + AC (pre-primary PCD) NT <0.01 μg/L

12.60 <0.01 μg/L

12.34 <0.01 μg/L

12.40 Lignite Fly ash + EA +AC (preprimary PCD) NT <0.01–0.016 μg/L

12.34–12.57 <0.01–0.061 μg/L

12.21–12.61 <0.01–0.016 μg/L

12.48–12.59 Lignite Fly ash + EA NT <0.01 μg/L

11.94 <0.01 μg/L

11.79 0.011 μg/L

12.00 Lignite Fly ash + AC (post-primary PCD) NT <0.01–0.012 μg/L

11.00–11.88 <0.01 μg/L

11.52–12.05 <0.01–0.028 μg/L

11.43–12.0952 Figure 5-1. Fly ash 18-hour SGLP leachate merc ury plotted against total mercury content.

Figure 5-2. Fly ash + AC and/or EA 18-hour SG LP leachate mercury plotted against total
mercury content.53 Table 5-27. Paired Samples Mercury 18- hour SGLP and TCLP Leachates and

Fundamental Characterization Data

ID Nos. Sample Type Total Hg, μg/g 18-hour SGLP Hg Leachate and pH TCLP Hg Leachate and pH 02-070 Fly ash 0.194 0.01 μg/L

10.55 0.03 μg/L

3.5602-069 Fly ash + ACI (postprimary PCD) 0.742 0.03 μg/L

9.48 0.07 μg/L

3.79 02-072 Fly ash 0.163 0.02 μg/L

10.81 0.02 μg/L

3.5402-071 Fly ash + ACI (postprimary PCD) 0.975 0.01 μg/L

9.89 <0.01 μg/L

4.06 02-076 Fly ash 0.607 0.016 μg/L

11.18 <0.01 μg/L

3.8903-009 Fly ash + ACI (preprimary PCD) NT <0.01 μg/L

11.71 <0.01 μg/L

4.2003-010 Fly ash + ACI (preprimary PCD) NT <0.01 μg/L

10.71 <0.01 μg/L

3.80

Table 5-28. Paired Mercury Leachates and Funda mental Characterizati on Data of Fly Ash Samples with Enhancing Agent and ACI

ID Nos. Sample Type Total Hg, μg/g 18-hour SGLP Hg Leachate and pH 30-day LTL Hg Leachate and pH 60-day LTL Hg Leachate and pH 04-035 Fly ash 0.159 0.081 μg/L

12.60 0.02 μg/L

12.65 <0.01 μg/L

12.5404-036 Fly ash + EA + ACI (preprimary PCD) 0.287 0.011 μg/L

12.56 <0.01 μg/L

12.61 <0.01 μg/L

12.59 05-001 Fly ash <0.01 <0.01 μg/L

12.42 0.011 μg/L

12.32 0.011 μg/L

12.3905-003 Fly ash + EA + ACI (preSDA) 0.565 <0.01 μg/L

12.34 0.043 μg/L

12.30 0.015 μg/L

12.49 05-005 Fly ash 0.431 <0.01 μg/L

11.69 <0.01 μg/L

11.74 <0.01 μg/L

11.83 05-017 Fly ash + EA 0.717 <0.01 μg/L

11.94 <0.01 μg/L

11.79 0.011 μg/L

12.00

In leachate from FGD–SDA samples (Table 5- 30), mercury was measured either at very low concentrations or was below the analytical reporting limit. Samples collected with and without mercury emission controls in place had similar mercury leachate concentrations. These data indicated that current manage ment practices can continue to be used for these samples. The paired sample data (as seen in Table 5-31) sh owed a definite increase in the total mercury content of the test sample over the baseline samples; however, no significant difference was noted in the mercury leachate concentrations fo r the FGD–SDA paired samples. No correlation

between the total and leachate merc ury concentrations was observed.54 Table 5-29. Paired Mercury Leachates and Fundamental Characterization Data of Fly Ash Samples with AC

ID Nos. Sample Type Total Hg, μg/g 18-hour SGLP Hg Leachate and pH 30-day LTL Hg Leachate and pH 60-day LTL Hg Leachate and pH 03-061 Fly ash 0.578 0.012 μg/L

12.45 <0.01 μg/L

12.63 0.325 μg/L

12.5803-060 Fly ash + AC (preprimary PCD) 1.86 0.015 μg/L

12.18 <0.01 μg/L

12.46 0.037 μg/L

12.38 05-038 Fly ash 0.104 <0.01 μg/L

11.85 <0.01 μg/L

12.00 <0.01 μg/L

12.0905-013 Fly ash + AC (postprimary PCD) 39.0 <0.01 μg/L

11.45 <0.01 μg/L

11.66 <0.01 μg/L

11.6105-023 Fly ash + AC (postprimary PCD: high ash) 12.7 <0.01 μg/L

11.85 <0.01 μg/L

12.05 <0.01 μg/L

12.09

05-024 Fly ash + AC (postprimary PCD) 35.9 <0.01 μg/L

11.51 <0.01 μg/L

11.67 <0.01 μg/L

11.6805-025 Fly ash + AC (postprimary PCD: high ash) 12.6 <0.01 μg/L

11.88 <0.01 μg/L

12.04 <0.01 μg/L

12.07

05-040 Fly ash + AC (postprimary PCD) 44.5 <0.01 μg/L

11.47 <0.01 μg/L

11.55 <0.01 μg/L

11.5406-001 Fly ash + AC (postprimary PCD) 64.5 <0.01 μg/L

11.39 <0.01 μg/L

11.52 <0.01 μg/L

11.47

Table 5-30. Ranges of FGD–SDA Mercury Leachate Results by Leaching Test, μg/L

Test FGD–SDA FGD–SDA + EA + AC (pre-primary PCD)

18-hour SGLP <0.01 <0.01 30-day LTL <0.01–0.050 <0.02 60-day LTL 0.013–0.043 0.012

Table 5-31. Paired FGD–SDA Mercury Leachates and Fundamental Characterization Data

ID Nos. Sample Type Total Hg, μg/g 18-hour SGLP Hg Leachate and pH 30-day LTL Hg Leachate and pH 60-day LTL Hg

Leachate and pH 05-002 FGD–SDA <0.01 <0.01 μg/L

12.40 0.050 μg/L

12.32 0.013 μg/L

12.47

05-004 FGD–SDA + EA + AC (pre-SDA) 0.332 <0.01 μg/L

12.43 <0.02 μg/L

12.48 0.012 μg/L

12.6055 Mercury leachate concentrations from the FGD materials noted in Table 5-32 were also generally low, but the 18-hour SGLP results for the wet FGD filtercake and fixated wet FGD material were higher than the other wet FGD materials, FGD–SDA, and fly ash samples.

Leachate data indicated that s hort-term mercury leachate concen trations from sulfite-rich wet FGD samples were somewhat elevated over the l ong-term mercury leachate concentrations, as also noted in Table 5-32. Leaching of FGD gyps um resulted in the lowest mercury leachate concentrations of all the wet FGD material sample s. The total mercury concentrations for all wet FGD material samples were very similar, but the da ta were insufficient to determine if there is a

correlation between total and le achate mercury concentrations. Further evaluation of a wide variety of wet FGD materials should include car eful identification of the sample type and location as well as factors that may impact th e mercury and ATE concentrations and leaching

behavior.

5.5.1.2 Arsenic

The ranges of arsenic leachate results by leaching test are re ported for all project fly ash samples in Table 5-33, FGD–SDA samples in Ta ble 5-34, and wet FGD samples in Table 5-35.

Table 5-32. Ranges of Wet FGD Material Mercury Leachate Results by Leaching Test, μg/L

Test FGD Gypsum Wet FGD Slurry Wet FGD

Filtercake Fixated Wet

FGD

18-hour SGLP <0.01 0.047 0.404–0.476 0.237–0.289 30-day LTL NT NT <0.01 <0.01 60-day LTL <0.01 NT <0.01 <0.01

Table 5-33. Range of Fly Ash Arsenic Leac hate Results by Leaching Test, μg/L

Test Fly Ash Fly Ash + AC (pre-primary PCD) Fly Ash + EA+ AC (preprimary PCD) Fly Ash + EA Fly Ash + AC (post-primary PCD)

18-hour SGLP <2–266 <4–16.3 <2–15.2 NT 20.2–842 30-day LTL <4–305 <2–9.9 <4–6.4 46.3 8.1–30.4 60-day LTL <2–336 <2–11.7 <2–7.5 73.0–95.9 10.4–27.3

Table 5-34. Ranges of FGD–SDA Arsenic Leachate Results by Leaching Test, μg/L

Test FGD–SDA FGD–SDA + EA + AC (pre-primary PCD)

18-hour SGLP 2.10–3.50 4.30 30-day LTL 2.60–3.30 3.60 60-day LTL 2.20–2.30 3.8056 Table 5-35. Ranges of Wet FGD Material Arsenic Leachate Results by Leaching Test, μg/L

Test FGD Gypsum Wet FGD Slurry Wet FGD

Filtercake Fixated Wet

FGD

18-hour SGLP <4 <4 <4 4.90–7.00 30-day LTL NT NT 3.50 5.20–24.0 60-day LTL <2 NT <2 <2–19.1

Arsenic leachate concentrations of fly ash + AC (pre-primary PCD), fly ash + EA + AC (pre-primary PCD), and fly ash + EA all were measured to be within the range reported for leachates from fly ash only. Total arsenic (Appendix G) was not elevated in any samples with AC or EA present. However, for the fly ash + AC collected post-primary PCD, several samples collected from a lignite-fired system had arseni c leachate concentrations significantly higher than the fly ash only, even though total arsenic concentrations were si milar. The leaching data from this paired sample set as noted in Figure 5-3.

The arsenic-leaching data for one set of paired fly ash samples is shown in Figure 5-3 with

the individual data from the 18-hour SGLP and 30- and 60-day LTL leaching test indicated for each sample. These samples were all collected fr om a system demonstra ting injection of AC after the primary PCD. These data show a leachi ng profile typical of alka line fly ash samples for elements that are present as oxyanions (arsen ic, boron, selenium, and others). As shown, the

arsenic leachate concentration decr eases with time. These specific sa mples also show an increase

Figure 5-3. Arsenic 18-hour SGLP and 30- and 60-day LTL leaching data for a paired sample

set.57 in the arsenic leachate concentrations in the te st samples as compared to the baseline sample even though the total arsenic concentrations in th ese samples were all similar. These data suggest that the AC may impact the leaching profile to facilitate increased arsenic release; however, other paired fly ash samples with AC injected post-primary PCD did not exhibit similar trends.

This observation should be considered as va rious CCBs from mercury emission controls are evaluated for leaching characterist ics, especially for arsenic since the arsenic limit for PDW was recently lowered to 10 μg/L.

Total arsenic concentrations were sim ilar for FGD–SDA samples evaluated, and the arsenic leachate concentrations were also similar, as shown in Table 5-34. Arsenic mobility from all FGD–SDA samples evaluated was low.

The arsenic-leachate concentrations for the various wet FGD materials noted in Table 5-35 were also very low, with the highest values noted for the fixated wet FGD material. The LTL

results also indicated an increase in arsenic leach ing with time for the fixated wet FGD materials.

5.5.1.3 Cadmium

The ranges of cadmium leachate results by l eaching test are reported in Tables 5-36 through 5-38 for fly ash samples, FGD–SDA samples, and wet FGD material samples, respectively.

For all sample types, cadmium leachate concen trations were generally low, but the highest cadmium leachate values were reported for the fl y ash samples without any emission controls in place. No increase in total cadmium content was noted with the presence of AC or EA. Cadmium leachate data are similarly low, varying within th e limits of the test and analysis, for all fly ash samples collected with mercury emission controls in place, all FGD–SDA materials, and all wet

FGD materials. The cadmium leachate values fo r the fly ash samples collected under mercury emission control conditions fell within the range of cadmium leachate concentrations for fly ash only. As observed in previous work, no trend is noted for cadmium leachate concentrations over

LTL.

Table 5-36. Ranges of Fly Ash Cadmium Leac hate Results by Leaching Test, μg/L

Test Fly Ash Fly Ash + AC (pre-primary PCD) Fly Ash + EA+ AC (preprimary PCD) Fly Ash + EA Fly Ash + AC (post-primary PCD)

18-hour

SGLP <0.2–8.08 <0.2–1.49 0.27–0.39 NT 0.99–1.87

30-day

LTL <0.2–7.64 <0.2–1.06 <0.2 2.40 0.85–1.99

60-day

LTL <0.2–8.30 <0.2–0.90 <0.2 <0.3–2.68 0.85–2.4658 Table 5-37. Ranges of Fly As h + FGD–SDA Material Cadmium Leachate Results by Leaching Test, μg/L

Test FGD–SDA FGD–SDA + EA + AC (pre-primary PCD)

18-hour SGLP 0.22–0.37 0.20 30-day LTL <0.2–0.58 <0.2 60-day LTL 0.20–0.59 <0.2

Table 5-38. Ranges of Wet FGD Material Cadmium Leachate Results by Leaching Test, μg/L

Test FGD Gypsum Wet FGD Slurry Wet FGD

Filtercake Fixated Wet

FGD

18-hour SGLP <0.2–0.46 <0.3 <0.2 0.43–0.44 30-day LTL NT NT 0.83 0.30–0.66 60-day LTL <0.2 NT 0.47 0.37–0.50

5.5.1.4 Chromium

The ranges of chromium leachate results for all project sample type s by leaching test are reported in Tables 5-39 through 5-41.

A comparison of all fly ash samples for total chromium versus leachate chromium was made (Appendix N), and results indicated that th ere may be an increased chromium leachate concentration for some fly ash samples with me rcury control. However, the paired samples

collected under this me rcury emission control configuratio n do not provide any indication of increased total chromium concentrations in the test samples over the baseline sample (see Table 5-10). Additionally, the leaching results for these paired samples did not show any changes in the leaching profile for test samples compared to the baseline sample. Chromium leachate concentrations were generally similar for fly as h samples with and without mercury controls in place, but the samples of fly ash + AC did yield some leachates with higher chromium concentrations. For paired samples, it was typical that changes in leachate concentrations noted over the LTL series results were the same for baseline and test samples. In some cases,

chromium leachate concentratio ns decreased with leaching time and, in some cases, the

chromium leachate concentrations increased with leaching time. No general trend was identified.

The decreases in chromium leachate concentrations with time were consistent with formation of secondary hydrated phases, but even though the pH of all samp les in the paired sample set was typical for these reactions to occu r, the data were inconclusive.

For FGD–SDA materials, the paired samples collected with mercury emission controls in place exhibited lower chromium le achate concentrations than t hose collected without mercury emission controls in place. For both the baseli ne and test samples, the 18-hour leachate had lower chromium concentrations than the long-term leachates.59 Table 5-39. Ranges of Fly Ash Chromium Le achate Results by Leaching Test, μg/L

Test Fly Ash Fly Ash + AC (pre-primary PCD) Fly Ash + EA+ AC (preprimary PCD) Fly Ash + EA Fly Ash + AC (post-primary PCD)

18-hour

SGLP 1.4–174 <50–560 <2–67.6 NT 17.3–410

30-day

LTL <2–265 3.6–147 <2–133 203 152–650

60-day

LTL <2–277 5.2–138 2.1–134 182–211 155–680

Table 5-40. Ranges of FGD–SDA Chromium Leachate Results by Leaching Test, μg/L

Test FGD–SDA FGD–SDA + EA + AC (pre-primary PCD)

18-hour SGLP 34.6–116 21.8 30-day LTL 113–215 67.7–78.0 60-day LTL 132–223 87.7

Table 5-41. Ranges of Wet FGD Materi al Chromium Leachate Results by Leaching Test, μg/L

Test FGD Gypsum Wet FGD Slurry Wet FGD

Filtercake Fixated Wet

FGD

18-hour SGLP <2 <2 <2 3.0–4.7 30-day LTL NT NT <2 2.2–3.1 60-day LTL <2 NT <2 2.4–3.3

Chromium concentrations were significantly lower in the wet FGD material leachates, but all wet FGD materials leached chromium at similarly low levels.

5.5.1.5 Lead

The ranges of lead leachate results are reported for fly ash samples in Table 5-42, FGD– SDA samples in Table 5-43, and wet F GD material samples in Table 5-44.

Lead leachate data indicated that nearly all leachate lead concentrations were below the analytical reporting level. In one paired sample set, the baseline sample had long-term leachate. The lead leachate results were consistent with data from previous studies and were generally very low.60 Table 5-42. Ranges of Fly Ash Lead Leac hate Results by Leaching Test, μg/L

Test Fly Ash Fly Ash + AC (pre-primary PCD) Fly Ash + EA+AC (preprimary PCD) Fly Ash + EA Fly Ash + AC (post-primary PCD)

18-hour

SGLP <2 <2 <2–3.0 NT <2

30-day

LTL <0.001–3.6 <2–3.0 <2 <2 <2

60-day

LTL <0.001–8.5 <2–2.4 <2 <2 <2

Table 5-43. Ranges of FGD–SDA Material Lead Leachate Results by Leaching Test, μg/L

Test FGD–SDA FGD–SDA + EA + AC (pre-primary PCD)

18-hour SGLP <2 <2 30-day LTL <2 <2 60-day LTL <2 <2

Table 5-44. Ranges of Wet FGD Material Lead Leachate Results by Leaching Test, μg/L

Test FGD Gypsum Wet FGD Slurry Wet FGD

Filtercake Fixated Wet

FGD

18-hour SGLP <2 <0.001 <2 6.60–14.3 30-day LTL NT NT <2 <2 60-day LTL <2 NT <2 <2

5.5.1.6 Nickel

Nickel-leaching data are presented in Tables 5-45 through 5-47. Results are shown for fly ash samples, FGD–SDA samples and wet FGD mate rial samples, and the SGLP–LTL tests used. An early evaluation of total nick el content (Appendix G) compared to leachate nickel content for all fly ash samples indicated that fly ash + AC sa mples exhibited reduced l eaching of nickel (see Appendix N). Continued laboratory evaluations indicated that th is observation was not supported by the nickel-leaching data on paired fly ash samp les. Nickel concentrations generally decrease over leaching time. Nickel usually does not partic ipate in reactions that form secondary hydrated phases.

Nickel-leaching results for F GD–SDA materials also indicat ed a decrease in leachate nickel concentrations with leaching time. The SG LP leachate nickel concentrations were higher than those reported for fly ash samples even th ough the total nickel content of fly ash samples and FGD–SDA materials was similar, and base line fly ash samples exhibited the highest

measured total nickel content.61 Table 5-45. Ranges of Fly Ash Nickel Leac hate Results by Leaching Test, μg/L

Test Fly Ash Fly Ash + AC (pre-primary PCD) Fly Ash + EA+ AC (preprimary PCD) Fly Ash + EA Fly Ash + AC (post-primary PCD)

18-hour

SGLP <2–80.6 <2–23.1 <2–25.2 NT <2–23.4

30-day

LTL <2–10.6 <2–5.4 <2–8.2 2.8 4.4–7.1

60-day

LTL <2–70.0 <2–5.3 <2–5.4 <4 2.9–5.1

Table 5-46. Ranges of FGD–SDA Nickel Leachate Results by Leaching Test, μg/L

Test FGD–SDA FGD–SDA + EA + AC (pre-primary PCD)

18-hour SGLP 16.4–39.1 29.3 30-day LTL <4 <4 60-day LTL <2 <2

Table 5-47. Ranges of Wet FGD Material Nickel Leachate Results by Leaching Test, μg/L

Test FGD Gypsum Wet FGD Slurry Wet FGD

Filtercake Fixated Wet

FGD

18-hour SGLP <2–28.4 15.0 6.1–7.4 <2 30-day LTL NT NT 32.1 <2–4.0 60-day LTL 10.1–12.6 NT 25.4 2.1–3.7

Leachate nickel concentrations for wet FGD materials were si milar to those for most fly ash samples and the FGD–SDA samples.

5.5.1.7 Selenium

Selenium was the only ATE other than merc ury identified as having increased total concentration in some fly ash + AC samples. Specifically, fly ash + AC samples where the AC was injected post-primary PCD ex hibited an elevated total sele nium content compared to the baseline for the single paired sample set of that type. Other fly ash paired samples that had the AC injected before the primary PCD did not exhibit this increase in total selenium content; however, the increase noted for the fly ash/fly ash + AC (post-primary PCD) samples and the properties of selenium raised interest in th e selenium-leaching data. The ranges of selenium leachate results by leaching test for fly ash, FGD–SD A, and wet FGD samples are reported in Tables 5-48 through 5-50, respectively.62 Table 5-48. Ranges of Fly Ash Selenium Le achate Results by Leaching Test, μg/L

Test Fly Ash Fly Ash + AC (pre-primary PCD) Fly Ash + EA +AC (preprimary PCD) Fly Ash + EA Fly Ash + AC (post-primary PCD)

18-hour SGLP 2.1–412 8.4–147 19.9–47.2 NT 99.3–8620 30-day LTL <2–489 <2–100 < 2–27.2 97.0 47.7–312 60-day LTL <2–514 3.8–114 < 2–30.3 <4–50.9 45.2–199

Table 5-49. Ranges of FGD–S DA Selenium Leachate Results by Leaching Test, μg/L

Test FGD–SDA FGD–SDA + EA + AC (pre-primary PCD)

18-hour SGLP 11.3–65.8 24.3 30-day LTL 12.0–65.2 12.0–13.2 60-day LTL 14.4–53.1 17.0

Table 5-50. Ranges of Wet FGD Material Se lenium Leachate Results by Leaching Test, μg/L

Test FGD Gypsum Wet FGD Slurry Wet FGD

Filtercake Fixated Wet

FGD

18-hour SGLP 3.3–18.7 65.0 41.0–71.2 2.1–2.70 30-day LTL NT NT 55.2 2.4–3.40 60-day LTL 2.7–8.2 NT 45.3 <2–2

5.5.2 Vapor-Phase Transport

Two types of vapor-phase transport (release) experiments were performed for this project: long-term ambient-temperature release expe riments and elevated-temperature release experiments. These experiments only measur ed mercury releases. No other ATEs were

determined.

5.5.2.1 Long-Term Ambient-Temperature Release

Over the course of this pr oject, the experimental result s and information obtained through the Year 1 field task, from documents assemble d, and through discussions with other research groups and sponsors, it became apparent that th e term “release” did not always describe the results of the ambient-temperature vapor-phase e xperimental results. The results of the ambienttemperature vapor-phase transport experiments we re reported as either mercury released or sorbed by the solid sample tested.

All samples included in the ambient-temper ature experiments and th e results are included in Appendix O. The experimental results are presented in sample sets because the experimental protocol required significant physical space and, therefore, limited the number of samples that could be evaluated at one time. Four sample se ts were evaluated for mercury captured in the63 analytical traps typically measured three tim es over the course of the experiment. The experiments were usually run for approximately 200 days, but selected samples were allowed to run for longer durations because of sample char acteristics or release pr ofiles. In the summary tables for this section, results for paired samp les are highlighted. The ta bles of summary data

include results of the two replicates of each sample expressed in two ways:

• Cumulative % Hg sorption or release refers to the amount of mercury sorption or

release based on the blank value measured over the entire experiment reported as a percentage of the total mercur y concentration of the sample.

• Years to release 100% Hg on CCB at measured rate is a calculation of the number of years required to release 100% of the total mercury content on the CCB at the rate of release measured over the experiment.

The first sample set evaluated comprised 12 samples and included fly ash, fly ash + AC (pre-primary PCD), and FGD–SDA samples fr om eastern bituminous, Powder River Basin (PRB) subbituminous, and lignite coal. One paired sample set (Samples 03-061 and 03-060) was evaluated. The samples and a summary of the results are shown in Table 5-51.

The results collected from Sample Set 1 are also shown graphically in Figure 5-4. Over the entire 194-day period of the experiment, five sa mples showed overall mercury release and seven samples showed overall mercury sorption. The rele ase of mercury, expressed as pg/g/day, was less for most samples in the final 90-day collectio n period than for the previous 90-day collection period. The observed variability was attributed to the variability i nherent in the analysis of the extremely low concentrations of mercury cap tured by and desorbed from the gold-coated analytical traps.

Samples included in Sample Set 2 and a summary of the results obtained are included in Table 5-52, and results are presen ted graphically in Figure 5-5. Th e sample set comprised seven samples including fly ash, fly ash + AC (post-primary PCD), fly ash + EA + AC (pre-primary PCD), and wet FGD filtercake fr om eastern bituminous, western bituminous, and lignite coal. One paired sample set (Samples 04-035 and 04-036) was evaluated.

In Sample Set 2, all fly ash samples sorbed mercury regardless of the presence of AC. The results from Sample Set 2 indicated that the release of mercury from the wet FGD filtercake sample (03-082) was higher than any releases meas ured for fly ash samples. Evaluation of this sample continued past that of the fly ash samples.

Based on this observation, Sample 03-082 was reevaluated in Sample Set 3. Also included in Sample Set 3 were fly ash, fly ash + EA + AC (pre-primary PCD), FGD–SDA, FGD–SDA + EA + AC (pre-SDA), and FGD gypsum from eastern bituminous, PRB subbituminous, and lignite coal. Two paired sample sets were eval uated. These included a fly ash pair (Samples 05- 001 and 05-003) and an FGD–SDA pair (Samples 05-002 and 05-004) from the same mercury control technology test. Results fo r Sample Set 3 are presented in Table 5-53. The results of the first 187 days of testing are disp layed graphically in Figure 5-6.64Table 5-51. Long-Term Ambient-Temperature Sample Set 1 Summary (Positive values indicate release, and negativevalues indicate sorption of mercury.Duplicate bottles are represented.)Replicate 1 Replicate 2ID No. Sample Type Coal TypeTotalHg onCCB,μg/gExp.Duration,DaysCumulative% HgSorption orReleaseYears toRelease 100%Hg on CCB atMeasured RateCumulative% HgSorption orReleaseYears to Release100% Hg onCCB at MeasuredRate01-002 Fly ash E. bit. 0.187 194−0.000153 NA – sorbing−0.000157 NA – sorbing03-006 Fly ash E. bit. 0.194 194−0.000110 NA – sorbing−0.0000845 NA – sorbing99-456 Fly ash PRB sub. 1.39 194−0.0000233 NA – sorbing−0.0000109 NA – sorbing01-008 Fly ash PRB sub. 1.22 194 0.0000037 14,472,785 0.0000000 NA – no sorptionor release03-061*Fly ashPRB sub.0.5781940.00000766,965,200−0.0000330NA – sorbing03-060Fly ash + AC (preprimary PCD)PRB sub.1.861940.000000774,619,3200.000002125,587,17503-017 Fly ash + AC (preprimary PCD)Lignite 0.225 194 0.0000045 118,14,972−0.0000966 NA – sorbing03-018 Fly ash + AC (preprimary PCD)Lignite 0.289 194 0.0000049 10,817,569−0.000122 NA – sorbing03-062 Fly ash + AC (preprimary PCD)Lignite 0.490 194 0.0000031 17,214,465 0.0000004 119,651,86199-188 FGD–SDA PRB sub. 0.112 194 0.0000026 20,144,056 -0.000657 NA – sorbing00-048 FGD–SDA Lignite 0.361 194−0.0000674 NA – sorbing 0.0000018 29,229,51701-011 FGD–SDA Lignite 2.55 194 0.0000006 82,875,125 0.0000008 68,131,501* Highlighted samples are paired samples.65Table 5-52. Long-Term Ambient-Temperature Sample Set 2 Summary(Positive values indicaterelease, and negative valuesindicate sorption of mercury. Duplicate bottles are represented.)Replicate 1 Replicate 2ID No. Sample TypeCoalTypeTotal Hgon CCB,μg/gExp.Duration,DaysCumulative %Hg Sorption orReleaseYears to Release100% Hg on CCBat Measured RateCumulative %Hg Sorption orReleaseYears to Release100% Hg on CCBat Measured Rate04-054 Fly ash + AC (postprimary PCD)E. bit. 17.7 188−0.0000008 NA – sorbing−0.0000012 NA – sorbing04-006 Fly ash W. bit. 0.144 188−0.000126 NA – sorbing−0.000235 NA – sorbing04-007 Fly ash W. bit. 0.521 188−0.0000685 NA – sorbing−0.0000168 NA – sorbing04-035*Fly ashLignite0.159188−0.0000646NA – sorbing−0.0000763NA – sorbing04-036Fly ash + EA + AC(pre-primary PCD)Lignite0.287188−0.0000392NA – sorbing−0.0000434NA – sorbing04-067 Fly ash + EA + AC(pre-primary PCD)Lignite 0.640 188−0.0000246 NA – sorbing−0.0000280 NA – sorbing03-082 Wet FGD filtercake E. bit. 0.248 699 0.609 315 0.448 428* Highlighted samples are paired samples.66 Figure 5-4. Sample Set 1 (194-day) long-term ambient-temperatur e mercury release or sorption as related to blank values, pg/g/day. Positive values indicate release, and negative values indicate sorption of mercury. Duplicat e bottles are represented.

Figure 5-5. Sample Set 2 (188-day) long-term ambient-temperatur e mercury release or sorption as related to blank values, pg/g/day. Positive values indicate release, and negative values indicate sorption of mercury. Duplicat e bottles are represented.67 Figure 5-6. Sample Set 3 (187-day) long-term ambient-temperatur e mercury release or sorption as related to blank values, pg/g/day. Positive values indicate release, and negative values indicate sorption of mercury. Duplicate bottles are re presented. Sample 03-082 is displayed on a secondary axis.

All fly ash samples in Sample Set 3 sorbed mercury. The FGD gypsum and wet FGD filtercake samples released mercury, with the wet FGD filtercake releasing at a rate of approximately over 100 times that of the FGD gypsum in the first 187 days of testing. The mercury determinations indicated that mercury re lease was continuing at that point, so the exposure to ambient air was c ontinued on all FGD material sa mples and mercury release was determined approximately every 45–60 days.

The cumulative mercury release for all the wet FGD material samples was higher than for any other samples evaluated. The rate of mercur y vapor release was also higher than fly ash samples. After extensive exposur e to ambient air, some of the wet FGD material samples, showed an indication of sorption of mercury.

Results for Sample Set 4 are shown in Table 5-54. This sample set included a set of paired fly ash samples, with 05-038 being the baseline sample, collected from a system where AC was injected after the primary PCD. The paired fly ash + AC samples in the set were test samples that had high or low ash content and va rying levels of AC present. The remaining two samples were FGD gypsum samples from the same plant, where Sample 04-082 was collected when the SCR was on and Sample 04-083 was collected when the SCR was off.68Table 5-53. Long-Term Ambient-Temperature Sample Set 3 Summary(Positive values indicaterelease, and negative valuesindicate sorption of mercury. Duplicate bottles are represented.)Replicate 1 Replicate 2ID No. Sample TypeCoalTypeTotal Hgon CCB,μg/gExp.Duration,DaysCumulative %Hg Sorption orReleaseYears to Release100% Hg on CCBat Measured RateCumulative %Hg Sorption orReleaseYears to Release100% Hg on CCBat Measured Rate04-029 Fly ash PRBsub.0.261 187−0.0000304 NA – sorbing−0.0000333 NA – sorbing04-044 Fly ash Lignite 0.878 187−0.0000245 NA – sorbing−0.0000129 NA – sorbing05-001*Fly ashLignite<0.01187−0.00238NA – sorbing−0.00392NA – sorbing05-003Fly ash + EA +AC (pre-primaryPCD)Lignite0.565187−0.0000234NA – sorbing−0.0000072NA – sorbing05-002FGD–SDALignite<0.01187−0.00548NA – sorbing−0.00119NA – sorbing05-004FGD–SDA + EA+ AC (pre-SDA)Lignite0.332187−0.0000611NA – sorbing−0.0000409NA – sorbing03-065 FGD gypsum E. bit. 0.044 473 0.00756 17,133 0.0111 11,67805-009 FGD gypsum E. bit. 0.032 473 0.0239 5,430 0.0190 6,83303-082 Wet FGDfiltercakeE. bit. 0.248 472 1.07 120 0.867 14903-082 Wet FGDfiltercakeE. bit. 0.248 476 0.866 151 0.963 135* Highlighted samples are paired samples.69Table 5-54. Long-Term Ambient-Temperature Sample Set 4 Summary(Positive values indicaterelease, and negative valuesindicate sorption of mercury. Duplicate bottles are represented.)Replicate 1 Replicate 2ID No. Sample TypeCoalTypeTotal Hgon CCB,μg/gExp.Duration,DaysCumulative% HgSorption orReleaseYears toRelease 100%Hg on CCB atMeasured RateCumulative% HgSorption orReleaseYears to Release100% Hg onCCB atMeasured Rate05-038*Fly ashLignite0.1041870.00002931,747,138−0.0000531NA – sorbing05-013Fly ash + AC (post-primaryPCD)Lignite39.01870.0000001388,756,0480.0000001399,977,49005-023Fly ash + AC (post-primaryPCD: high ash)Lignite12.71870.0000003173,663,7040.0000004125,457,46505-024Fly ash + AC (post-primaryPCD)Lignite35.9187−0.0000001NA – sorbing−0.0000001NA – sorbing05-025Fly ash + AC (post-primaryPCD: high ash)Lignite12.6187−0.0000017NA – sorbing−0.0000019NA – sorbing05-040Fly ash + AC (post-primaryPCD)Lignite44.51870.00000006,414,372,585−0.0000005NA – sorbing06-001Fly ash + AC (post-primaryPCD)Lignite64.5187−0.0000003NA – sorbing−0.0000003NA – sorbing04-082 FGD gypsum E. bit. 0.0427 200 8.41 6.51 8.38 6.5404-083 FGD gypsum E. bit. 0.103 200 0.381 144 0.282 194* Highlighted samples are paired samples.70 The fly ash and fly ash + AC samples in Sample Set 4 generally sorbed mercury or showed very low releases. Although Sample 04-082 (SCR on) had a lower total mercury concentration than Sample 04-083 (SCR off), it released a gr eater percentage of mercury. Sample 04-082 showed the highest mercury release in this proj ect. Figure 5-7 graphically presents the rate of mercury release, pg/g/day, from Samples 04-082 a nd 04-083. This clearly shows that the release of mercury from Sample 04-082 is decreasing with time.

Review of the results of long-term ambient-temperature release tests indicated that mercury might be released from some CCBs at relatively low levels. Fly ash that had unburned carbon or AC generally tended to sorb mercury from the ambient air that was introduced into the sample container. For fly ash samples, the rele ase of mercury was higher for each sample in the first period than in subsequent pe riods, indicating a reduced rate of release with time. This is due to the disruption of the sample and apparatu s during sample additi on to the container.

Wet FGD materials all released mercury at hi gher levels than any of the fly ash samples evaluated, and the calculated numbe r of years to complete release of mercury was the lowest for the wet FGD material samples, ranging from 6 to 428 years, while the calculated years to complete release were greater than 50M years + for fly ash and FGD–SDA samples evaluated. Generally, the rate of release measured in the fi nal testing period was decreasing compared to the prior testing period; ther efore, the calculated years to rel ease 100% of the total Hg on the CCB is likely low. The results indicate that the releas e or sorption of mercur y from fly ash and FGD– SDA samples is very minute and would cause no adverse impact on the mercury loading to the atmosphere.

Figure 5-7. Long-term ambient-temperature merc ury release rate, pg/g/day, from Samples 04- 082 and 04-083. Duplicate bot tles are represented.71 5.5.2.2 Desorption at Elevated Temperatures

A variety of CCBs were evaluated for the real-time elevated-temperature release of mercury. The CCBs were primarily fly ash. Evalua tion of FGD materials was limited because of analytical interference from the releases of sulfur compounds on sample exposure to elevated temperatures. The use of elevated-temperature re lease of mercury was evaluated as a means of determining the speciation of me rcury present on CCBs. An elev ated-temperature vapor-phase mercury release report was published in Februa ry 2006 and can be found in Appendix P. This report included a complete discussion of the work performed to evaluate the mercury releases from CCBs on exposure to elevated temperatur es, and the results are summarized here. All results can be found in Appendix Q.

Thermal desorption curves provided a comparative means of evaluating the elevated-temperature release of mercury from a variety of CCBs . Mercury thermal desorption curves were generated for 65 CCBs, including 31 fly ash samples and 28 fly ash samples with mercury control, two FGD–SDA samples and one FGD–SDA sample with mercury control, and

three wet FGD materials. Tables 5-55 and 5-56 list the samples evaluated indicating the coal source and mercury control. Although three we t FGD materials were tested, analytical interferences precluded conti nued work on FGD materials.

The fly ash samples subjected to the elevated-temperature regime typically generated either one or two mercury peaks, with four be ing the maximum number of peaks identified for fly ash. As also noted in Table 5-55, mercury wa s released at temperatures ranging from 256° to 750°C. Some samples continued to show increa sing mercury release at 750°C, so the highest peak temperature at which the mercury was released could not be determined. Samples exhibiting this continued mercur y release at 750°C were predom inantly eastern bituminous fly ash samples with a LOI greater th an 3% or fly ash + AC (post- primary PCD) samples. Samples with added AC were more difficult to replicate in part because the mercur y was likely associated with the carbon particles, and it wa s more difficult to take a repr esentative sample of fly ash + AC, especially with the sample size limitati ons of the method. Some samples were ground or

sieved in order to obtain a more homogeneous sample for evaluation.

Although the lowest mercury absorbance peak o ccurred at 256°C for a fly ash sample, the initiation of the first mercury release peak wa s noted before 250°C. Representative mercury release curves generated under this task are sh own in the report in Appendix P. Examples of replicate curves are also shown in the report. An example of a de sorption curve with two peaks is shown in Figure 5-8. The relatively sharp first p eak was typical of most first mercury peaks recorded. In curves where two or more peaks we re noted, peaks after the initial peak tended to show slightly less definition and were usually broader, although the absorption could be higher.

Samples with AC were more difficult to evaluate for elevated-temperature mercury releases, but sorbents that contained other comp ounds, such as halogens or sulfur, also offered analytical challenges. While sample identifications did not always indicate th e exact nature of the72 Table 5-55. Summary of Fly Ash Samples Evaluated in Elevated-Temperature Mercury Release Experiments

Coal Type Sample Type No. of Samples

Tested No. of

Peaks Range of Temp. at Peaks, °C Total Hg

Content Range, μg/g LOI Range,

%

Eastern

Bituminous Fly ash 16 0–4 260–750 <0.01–0.685 0.47–8.46

Fly ash + AC (post-primary PCD) 6 1–4 262–750 0.742–120 12.6–24.4

South American

Bituminous Fly ash 2 1–3 356–750 0.151–0.607 12.7–21.2

Western

Bituminous Fly ash 2 1 330–378 0.144–0.521 1.42–2.56

PRB

Subbituminous Fly ash 2 1 333–404 0.261–0.578 0.48–1.08

Fly ash + AC (pre-primary PCD) 4 1–2 302–750 1.09–5.81 2.28–4.14

Fort Union Lignite Fly ash 9 0–3 275–750 <0.01–0.785 0.22–7.48

Fly ash + AC (pre-primary PCD) 4 1 323–702 0.225–2.22 0.96–4.21

Fly ash + EA +AC (preprimary PCD) 3 1–2 306–750 0.287–0.640 1.04–2.49

Fly ash + EA 1 0–2 388–684 0.717 1.70 Fly ash + AC (post-primary PCD) 10 0–3 256–750 0.147–64.5 0.59–13.2

AC used, samples of this type were expected to produce a thermal curve containing multiple peaks. Multiple peaks were noted in a significant number of fly ash samples and were likely due to the presence of multiple mercury compounds in th e samples (mercury chloride, oxide, nitrate, or sulfate) because each com pound would be expected to result in a discreet peak on vaporization.

Elemental mercury is known to sorb as an oxidized species on AC. Additives such as sulfur or iodine, for ex ample, could lead to the formation of additional compounds such as73 Table 5-56. Summary of FGD–SDA and Wet FGD Material Samples Evaluated in Elevated-Temperature Mercury Release Experiments

Coal Type Sample Type No. of Samples

Tested No. of

Peaks Range of Temp. at Peaks, °C Total Hg

Content Range,

μg/g LOI Range, %

PRB

Subbituminous FGD–SDA 1 2–3 270–695 0.0716–

0.131 2.07

Fort Union Lignite FGD–SDA 1 0 NA <0.01 0.95

FGD–SDA +EA + AC (preSDA) 1 1 312–487 0.332 1.12

Eastern

Bituminous FGD gypsum 2 1 298–329 0.044–

0.096 1.22–

1.94

Fixated wet

FGD 1 3 256–720 0.180 3.11–

3.17

mercuric sulfide or mercuric iodide. The ther mal desorption curves were indicative of the following mechanisms of desorption:

• Elemental mercury and mercuric chloride can desorb unchanged.

• Other mercury compounds can decompose in to their components as would happen with mercuric oxide, which would decompose in to oxygen and elemental mercury prior to desorption.

Table 5-57 shows comparative data for fly as h samples subjected to elevated temperature. The table shows ranges of the temp eratures recorded for the initi ation and peak of each mercury peak noted for fly ash samples evaluated. The da ta indicated that the addition of an EA may result in fewer peaks to be generated both when us ed alone or with AC fo r mercury control. This same phenomenon was noted for the FGD–SDA sample shown in Table 5-58. The wet FGD materials (results summarized in Table 5-58) produced fewer me rcury peaks, and the mercury tended to desorb at lower temperatures than not ed for samples of fly ash and FGD–SDA. Results for FGD–SDA samples tended to be more reproduc ible than results from fly ash samples.

5.5.2.3 Mercury Speciation Method

An effort was made to use the elevated-tem perature apparatus to develop information on the species of mercury present on the CCBs tested. The presence of multiple peaks was potentially indicative of multip le mercury compounds being desorbed. The mercury speciation investigation was initiated with the use of qua rtz sand and pure quartz pow der, spiked with74 Figure 5-8. Typical two-peak merc ury desorption curve for fly ash.

Table 5-57. Range of Fly Ash Peak Mercury Release Temperatures at Elevated Temperature, °C

Peak Fly Ash Fly Ash + AC (pre-primary PCD) Fly Ash + EA+ AC (preprimary PCD) Fly Ash + EA Fly Ash + AC (post-primary PCD)

Peak 1 Start 173–645 226–433 275–371 339–372 135–540

Peak 1 273–750 302–702 324–433 388–406 262–750

Peak 2 Start 315–705 388–657 350 388 290–710

Peak 2 346–750 363–750 750 417–684 330–751

Peak 3 Start 454–709 687 NA NA 362–750

Peak 3 551–750 704–750 NA 578 411–750

Peak 4 Start 629 NA NA NA 515–750

Peak 4 737–747 750 NA NA 705–750

Table 5-58. Range of FGD–SDA and Wet FGD Material Peak Mercury Release Temperatures at Elevated Temperature, °C

Peak FGD–SDA FGD–SDA + EA + AC FGD Gypsum Fixated FGD Peak 1 Start 200 (3 times) 264–280 170–250 157

Peak 1 275–280 312–354 298–329 256

Peak 2 Start 412–416 NA NA 430

Peak 2 430–475 487 NA 460

Peak 3 Start NA NA NA 670

Peak 3 695 NA NA 72075 mercuric chloride. Quartz was selected as an in ert material. A single, sharp peak was recorded when the mercuric chloride was added to the qu artz sand. However, when mercuric chloride was spiked onto pure quartz powder, a double peak was noted.

Additional elevated-temperatu re release experiments were also performed on CCB samples spiked with mercury. All samples used in this ex periment were fly ash, so me of which contained AC or EA plus AC from merc ury emission control demonstrati ons. The addition of mercuric chloride or elemental mercury vapor to the CCBs re sulted in a shift of the mercury release peaks noted previously from the samples without any added mercury. The peak temperatures measured for spiked CCB samples shifted to higher temp eratures for some samples and to lower temperatures for other samples. This indicated th at the temperature range for mercuric chloride in CCBs was too wide for positive identific ation of a peak as a particular compound.

Figures 10 and 11 in Appendix P are an exampl e of a fly ash sample tested as described earlier compared to a separate aliquot spiked with mercuric chloride. This was done by mixing a single aliquot of the CCB, just less than 2 grams, and dividing it into two small, nearly equal portions. One portion was left untreated while the other portion was spiked with 50 μL of an

ether solution of mercuric chlori de containing 10 ng/μL of mercuric chloride. This is equivalent to the addition of 370 ng of mercury as mercuric chloride. Spiking was done in this manner to minimize nonhomogeneity between the two aliquots of sample. Mercuric chloride spiking of this fly ash sample produced an additional peak to those noted on the origin al fly ash sample. The reasons for an additional peak noted in the spiked sample are the same as why a fly ash sample may release multiple peaks of mercury.

Results indicated that the in teraction of mercury and merc ury compounds with the CCBs at elevated temperatures may precl ude speciation using this method on these complex materials. It is hypothesized that the first peak that evolves from each CCB is sorbed elemental mercury,

which can volatilize more r eadily than mercury compounds.

5.5.3 Microbiologically Mediated Leac hing and Vapor-Phase Transport

A variety of CCB samples were evaluated for microbiologically mediated mercury releases using the methods described in the experi mental section and in a report entitled “Microbiologically Mediated Mercury and Air T oxic Element Rereleases from Coal Combustion By-Products,” and submitted to project sponsors in 2006. The report is included in its entirety in Appendix R. The report summarizes the bulk of the work performed under this subtask. The work included significant efforts to modify the experimental method and apparatus used to allow determination of mercury released from sample s of CCB subjected to conditions conducive to microbial growth. The samples included in this subtask were primarily fly ash. A complete summary of the samples evaluated and identify ing information is included in Appendix S.

As described in the report noted, six sets of microbiologica lly mediated experiments were completed, and a seventh set was run after prepar ation of that report. The experimental method was designed to determine the leaching and vapo r-phase releases from the CCBs under aerobic and anaerobic conditions with appr opriate buffer to keep the pH of the systems in a range that would allow the microbes to reproduce.76 In keeping with the format used in the re port included as Appendix R, a summary of the samples and results from Experiment 7 are in cluded here. Table 5-59 provides information on the samples evaluated. The samples were all bi tuminous fly ash without any mercury emission controls in place. Results of Experiment 6 indi cated that high-pH fly ash typically generated from North Dakota lignite or subbituminous coal, cannot be maintained at a pH level that will support microbial growth. For that reason, the fina l experiment focused on fly ash samples with near-neutral pH values.

Microbiological release Experiment 7 in cluded aerobic and an aerobic glucose-fed conditions in triplicate similar to the earlier experiments. A 4-day initial elemental mercury release measurement was made for the samples, which was the period between sample and

buffer addition and bacteria addition to the flas k. Observations included possible fungal growth within three days of bacteria a ddition in most sample flasks and a moldy or musty odor in the air over the aerobic side of the expe rimental setup 10 days after bact eria addition. In some samples, a gray mold was clearly visible.

Analytical data were collected at the end of the monthlong e xperiment and are reported in Tables 5-60–5-62. Prior to prepar ations necessary for sample analyses, the condition of each flask sample was noted after settling of the solids. All anaerobic sample flasks contained a clear liquid and had no odor. All aerobic sample flasks contained a dark gray to black, opaque liquid. All but one of the aerobic sample flasks (Sampl e 04-003) had a slightly musty odor. Many of the aerobic sample flasks had varying amounts of sma ll white specks or a film that were possibly fungus. One of the aerobic flasks for Sample 03- 006 had a definite fungus or mold patch on the top of the liquid. The liquid samples from the aerobi c side of the experiment required the use of a centrifuge to separate the liquid and solid enou gh to filter through a 0.45-μm filter. Eh and pH measurements of all filtered liqui d samples are reported in Table 5-60.

Table 5-61 reports the elemental and orga nomercury vapor-phase release results in pg/g/day. The samples on the aerobic side rele ased more vapor-phase mercury with one exception.

Results of the mercury and trace element leachat e concentrations from that experiment are shown in Table 5-62. The aerobic trace element results were reported as the dissolved

concentration versus the total concentration. Table 5-62 shows several clear differences in

leachate concentrations of select trace elements between aerobic and anaerobic conditions. Under aerobic conditions, concentrations of arsenic, lead, and mercury with one exception, were

Table 5-59. Microbiological Release Exp eriment Sample Summary, Experiment 7 ID No. Sample Type Coal Type 24-hour pH Total Hg, μg/g 03-006 Fly ash Eastern bituminous 6.78 0.194 03-007 Fly ash Eastern bituminous 5.52 0.141 04-003 Fly ash Eastern bituminous 8.54 0.685 05-018 Fly ash Eastern bituminous 8.49 0.12377 Table 5-60. Microbiological Expe riment 7 Eh and pH Results

Anaerobic Aerobic ID No. Eh, mV pH ID No. Eh, mV pH

03-006 209.0 6.98 03-006 98.3 8.87

03-006 177.3 7.00 03-006 196 8.78

03-006 167.7 6.87 03-006 83.8 8.70

03-007 207.5 6.71 03-007 126 8.64

03-007 178.3 6.64 03-007 195 8.72

03-007 163.5 6.69 03-007 103 8.65

04-003 95.3 6.95 04-003 156 8.77

04-003 51.4 8.49 04-003 119 8.60

04-003 62.3 8.49 04-003 98.5 8.61

05-018 14.2 7.91 05-018 149 8.60

05-018 11.5 7.86 05-018 97.0 8.63

05-018 2.4 8.06 05-018 116 8.54

Table 5-61. Vapor-Phase Mercury Release Results, pg/g/day, Experiment 7

Anaerobic Aerobic ID No. Elemental Mercury Organomercury ID No. Elemental Mercury Organomercury

03-006 0.130 0.164 03-006 17.9 1.91

03-006 0.255 0.095 03-006 5.36 0.524

03-006 0.178 0.075 03-006 6.08 0.752

03-007 0.253 0.050 03-007 5.89 0.206

03-007 6.17 0.104 03-007 1.11 0.215

03-007 0.388 0.180 03-007 13.6 1.51

04-003 0.068 0.046 04-003 15.6 0.035

04-003 0.249 0.057 04-003 4.17 0.085

04-003 0.285 0.039 04-003 10.3 0.174

05-018 12.1 0.763 05-018 17.7 1.07

05-018 0.797 0.120 05-018 21.3 0.717

05-018 1.74 0.212 05-018 34.9 3.24

elevated. Under anaerobic conditio ns, concentrations of chromium, nickel, and selenium were elevated. Under both conditions, concentrations of cadmium remained about the same. It could be hypothesized that since under ae robic conditions pH values were elevated, simple pH control of conditions would explain the leachate concen trations. However, the slightly depressed concentrations of cadmium in the aerobic expe riments make that unlikely. Cadmium solubility over the pH range 6–9 would be exp ected to be much like that of lead and it was not. It is likely that in these experiments it was the differences in microbial and fungal popul ations that exerted a major influence in the final solution concentrations of trace elements.

Summaries of vapor-phase rele ase information generated in al l experiments in this subtask are included in Tables 5-63 for fly ash samples and 5-64 for FGD–SDA and wet FGD filtercake.78Table 5-62. Microbiologically Leached Total Trace Element Results, μg/L, Experiment 7Anaerobic AerobicID No. As Cd Cr Pb Hg Ni Se pH ID No. As Cd Cr Pb Hg Ni Se pH03-006 644 3.40 6.8 <2 0.134 128 608 6.98 03-006 2190 2.42 3.4 59.8 NT 8.6 216 8.8703-006 663 3.37 6.8 <2 <0.01 122 617 7.00 03-006 2310 2.53 3.1 15.8 0.120 15.5 217 8.7803-006 638 3.68 7.2 <2 <0.01 122 607 6.87 03-006 2160 2.25 <2 6.6 0.023 7.9 169 8.7003-007 398 4.55 6.6 <2 <0.01 144 585 6.71 03-007 2010 2.67 <2 4.1 0.025 33.9 162 8.6403-007 419 4.34 6.4 <2 <0.01 125 616 6.64 03-007 1320 3.13 3.5 8.4 <0.01 58.8 198 8.7203-007 421 4.50 6.4 <2 0.247 125 602 6.69 03-007 1820 2.61 3.6 3.8 0.079 6.9 119 8.6504-003 438 2.32 8.8 <2 0.009 111 655 6.95 04-003 1300 1.78 5.3 3.5 0.172 4.9 354 8.7704-003 569 2.33 12.7 <2 <0.01 160 793 8.49 04-003 1170 1.70 3.1 3.2 0.157 8.1 300 8.6004-003 596 2.38 12.9 <2 <0.01 160 823 8.49 04-003 1320 1.81 7.1 2.2 0.356 10.8 368 8.6105-018 785 11.6 11.3 <2 NT 270 753 7.91 05-018 1290 7.96 4.1 5.1 0.191 58.1 378 8.6005-018 726 10.9 10.4 <2 NT 249 723 7.86 05-018 1520 8.01 5.3 9.8 0.124 43.9 483 8.6305-018 772 10.8 13.8 <2 NT 278 725 8.06 05-018 1370 8.51 4.0 3.3 0.164 259 471 8.54Table 5-63. Summary of Vapor-Phase MercuryReleases from Microbiologically MediatedExperiments on Fly Ash SamplesVapor-Phase Hg Releases, pg/g/dayAnaerobic AerobicExperimentNo.ID No. Sample Type Coal TypeTotal Hg,μg/gElementalHgOrgano HgElementalHgOrgano Hg2 01-002 FA Bituminous 0.785 0.1 – 0.24 0.008 –0.0090.09 – 1.1 0.008 –0.0323 03-060 FA + AC Subtuminous 0.689 0.03 – 0.09 0.002 –0.0080.65 – 1.7 0.007 –0.0104 03-079 FA Lignite 0.160 0.56 – 1.06 1.00 – 1.34 2.26 – 3.96 0.50 – 6.164 04-043 FA Lignite 0.287 0.26 – 0.44 0.12 – 0.22 0.08 – 9.30 0.26 – 0.905*04-035FALignite0.1940.03 – 0.040.03 – 0.140.15 – 0.200.02 – 0.11504-036FA + ACLignite0.410.03 – 0.520.02 – 0.140.26 – 0.450.07 – 0.117 03-006 FA Bituminous 0.685 0.13 – 0.25 0.07 – 0.16 5.36 – 17.9 0.52 – 1.917 03-007 FA Bituminous 0.123 0.25 – 6.17 0.05 – 0.18 1.11 – 13.6 0.21 – 1.517 04-003 FA Bituminous 0.234 0.07 – 0.28 0.04 – 0.06 4.17 – 15.6 0.04 – 0.177 05-018 FA Bituminous 1.86 0.80 – 12.1 0.12 – 0.76 17.7 – 34.9 0.72 – 3.24* Shading indicates paired samples.79 Key observations made based on the results of these experiments are as follows:

• Analysis of mercury was hindered by high an alytical blanks and generation of hydrogen sulfide from high-sulfur samples that contaminated the analytical traps.

• Maintenance of neutral pH and associated microbial growth could not be achieved for samples with an initially high pH.

• Fungi was present in some samples unde r aerobic conditions and, when fungi was noted, the vapor-phase mercury releases were higher than in replicate sample flasks where no fungi was evident.

• Aerobic conditions resulted in increased vapor-phase mercury releases for both elemental and organomercury for all samples evaluated.

• The FGD–SDA and wet FGD filtercake exhibited significantly higher vapor-phase mercury release rates than the fly ash sa mples evaluated, and the FGD–SDA sample evaluated had the highest releas e rate of vapor-phase mercury.

• The formation of organomercury compounds wa s evident in all of the microbiologically mediated experiments. It was observed, howev er, that organomercury formation appears to be directly related to the amount of fungi present in the flasks at the end of the experiments.

• The mercury released from the CCB slurry was generally higher in the samples fed with glucose versus starved samples. The fina l experiments only included “fed” systems.

Sulfate-reducing bacteria in su lfur-rich samples such as FGD material tended to form large amounts of hydrogen sulfide in th e anaerobic flasks. This hydr ogen sulfide production required putting traps on the flasks in order to keep the hy drogen sulfide and its odor out of the lab. The

Table 5-64. Summary of Vapor-Phase Mercury Releases from Microbiologically Mediated Experiments on FGD–SDA and Wet FGD Filtercake Samples Vapor-Phase Releases, pg/g/day

Anaerobic Aerobic

Experiment

No. ID No. Sample Type Coal Type Total Hg, μg/g Total Hg Organo Hg Total Hg Organo Hg

1 99-188 FGD–SDA Subbituminous 0.131 31.5 –

43.5 NT 1090 –

2110 NT

4 03-082 Wet FGD

Filtercake Bituminous 0.218 0.14 –

2.54 0.52 –

20.4 97.2 –

130 18 – 22

5 1 03-082 Wet FGD

Filtercake Bituminous 0.218 1.54 NT 4.64 –

9.69 0.94 –

1.62

1 Microbes were not added.80 hydrogen sulfide also made analyses impossible becau se of the formation of colloidal sulfur soon after the samples were harves ted. Additionally, hydrogen sulfide collected in the CarbotrapTM

tubes came off as elemental sulfur and precluded analyses of thes e traps in our normal manner. No solutions were developed to solve this analytical problem.

Highly alkaline ash samples generated from li gnite have proven part icularly difficult to maintain at near neutrality. Experiments performed in the absence of bacteria provide us with a neutralization capacity for acid a ddition, but in microbiological e xperiments, thes e neutralized solutions quickly rose to above pH 10.5, thus k illing the bacteria. We had been using dilute

sulfuric acid for neutralization and believe that afte r neutralization, a sulfate coating has deposited around individual particles. After bact eria were introduced, we believe that the bacterial action may have removed the protective sulfate coating from alkaline particles, thus releasing additional alkalinity. At this time, th is is our only working hypothesis, and solutions based on this hypothesis are under investigation.

It is important to note that although methylat ion did predictably occur, the apparent rate

and resultant concentrations of methylmercury were extremely small. Research on the issue of methylation of mercury and other trace elements such as selenium and arsenic are currently ongoing. Despite the extreme toxicity of methylated mercury species, there does not appear to be evidence that would lead to any need for special precautions at this time. Methylation of select trace elements is a phenomenon that should be exp ected to occur and which is known to occur in sites with natural sources of arsenic, mercur y, and selenium. The research team’s primary observation was that the presence of fungi under aerobic conditions appears to be a primary source of methyl mercury. It was expected at the onset of these experiments that the presence of sulfate-reducing bacteria under an aerobic conditions would be a primary source of methylation. This was not the case despite the presence of sulfate-reducing bacteria in samples with high

concentrations of sulfate.

The presence of these speci fic bacteria was determined by the strong odor of hydrogen sulfide in samples with high c oncentrations of sulfate under an aerobic conditions. The presence of hydrogen sulfide was significan t enough that scrubbers were adde d to the flasks in order to keep the air in the lab breathable.

5.6 Field Investigations

The goal of the field investigation task was to develop information to facilitate an understanding of how laboratory results could be us ed to understand the potential for releases of ATEs from CCBs in real-world management setti ngs. As already stated, fi eld concentrations of constituents released from CCBs by exposure to water cannot be predicted by laboratory leaching test results, but leaching can provide information that can be used to determine if the potential for mobility of one or more constituents is at a level that warrants further consideration prior to a material being placed in specific envi ronmental settings or conditions. The field task focused on obtaining information on mercury concentrations in the air near and around CCB disposal facilities in order to make a preliminary determination on how to best use results from laboratory vapor-phase experiment s to provide information valuable in an assessment of the potential for vapor-phase mercury release to imp act atmospheric mercury loading. This task was81 accomplished in two subtasks: 1) Evaluation of Vapor-Phase Mercury at CCB Disposal Sites and 2) Small-Scale Vapor-Phase Mercury Release fr om Soil–Ash Mixtures. On completion of the first field subtask, the data were reviewed and compared with othe r field data, and it was agreed by project sponsors that instead of performing anot her field site investigation, it would be more valuable to carry out a small-scale evaluation of vapor-phase mercury release from soil–ash

mixtures since this was an ash utilization scenario that might fall under scrutiny by regulatory agencies and citizen groups.

5.6.1 Field Task 1

The first subtask of the fi eld investigation task was performed at CCB management facilities associated with a lignite-fired power plant. The EERC contracted with UNR to perform the mercury flux measurements using a mercury flux chamber as reported previously by UNR (Engle et al., 2001; Xin et al., 2006). The field task consisted of th ree key activities: 1) collection of near-surface solid samples and water samples, where available; 2) mercury flux measurements taken at near-surface locations by UNR; and 3) co llection of mercury samples from CCB landfill air at near-surface locations by the EERC. Air sampling was perfor med at a variety of locations

as described in Table 4-3.

5.6.1.1 Measurement of Mercury in Field-Collected Solid Samples

Water samples and replicate solid samples (EERC and UNR) were obtained for laboratory testing. Solid composite samples were taken of the substrate on which the mercury air sampling was conducted. Composite samples are described in Table 4-3. Liquid sample s were collected at disposal ponds where possible.

Averages of total mercury content of sa mples collected by both the EERC and UNR are noted in Table 5-65. Results from the two entities were similar for each jointly sampled substrate type. The total mercury concentrations for fly as h samples were low. The wet FGD material had the highest total mercury. The fly ash and botto m ash/mill rejects + wet FGD material total mercury contents were lower than the natural grasslands (background soil ) and agricultural land.

Fundamental characterizations of the solid samples collected in the field by the EERC are noted in Table 5-66 and Appendix T. The stabilized FGD material (with fly ash) had the widest total mercury range. Moisture content and LOI in the bottom ash/mill rejects + wet FGD material samples exhibited the widest range of values. The range of pH values was similar in all samples.

5.6.1.2 Measurement of Mercury Flux by UNR

In situ mercury fluxes were measured unde r highly variable weat her conditions ranging from bright, sunny days to cold, rainy days with strong wind. Measurements of relative humidity (24%–84%), solar ir radiance (36–761 W/m 2 ), and temperature (8.6°–33.1°C) were made and varied widely depending on the weather condition s. Mercury flux measurements were performed at seven locations with varying substrates , and results are summa rized in Table 5-67.82 Table 5-65. Field Sample Composites and Associated CCB Mercury Analysis Results, average

Sample Type Total Hg, μg/g

EERC Results Total Hg, μg/g UNR Results (Xin and Gustin, 2005) Fly Ash <0.01 <0.015 Vegetated Fly Ash with Soil

Cover NT 0.095

Wet FGD Material + Mill Rejects 0.197 0.179

Wet FGD Material 0.299 0.360 Bottom Ash/Mill Rejects + Wet

FGD Material 0.014 NT

Stabilized Wet FGD Material (with fly ash) 0.114 0.23

Natural Grasslands (background soil) 0.050 0.05

Agricultural Land NT 0.03

Table 5-66. Range of Fundamental Characteriza tion Data in Field Samples Collected by

the EERC

Sample Type Total Mercury Content, μg/g Moisture Content, % LOI, % 10–15-min pH Overnight pH Fly Ash <0.01 15.0 5.73 9.36 9.13

Wet FGD Material + Mill Rejects 0.188–0.207 19.3–21.3 2.18–3.31 8.62–8.68 8.51–8.53

Wet FGD Material 0.299 23.3 2.49 8.55 8.27

Stabilized Wet FGD Material (with fly ash) 0.011–0.250 10.1–23.5 2.68–3.68 8.72–10.33 8.63–10.81

Bottom Ash/Mill Rejects + Wet

FGD Material <0.01–0.044 7.02–28.8 1.99–13.0 8.77–9.78 9.29–10.33

Natural Grasslands (background soil) 0.050 12.6 6.88 8.57 8.40

Mercury flux was measured from eleven areas at the site. Five fl y ash-sampling locations with low mercury emission fluxes (from 0.0 to 1.8 ng/m 2 /hr) were measured, while two fly ash sites had higher emissions (4.5 ± 3.3 and 4.9 ± 2.5 ng/m 2 /hr). For two other sites, the mean flux indicated deposition of atmospheric me rcury to the fly ash during the day.

Mercury flux was also measured from three si tes on a vegetated fly ash substrate. The fly

ash was covered with a 2 ’ clay cap and a 3 ’ vegetated soil layer. Two of the measurement sites exhibited low mean mercury em ission rates (0.9 and 1.3 ng/m 2 /hr), and one site had an83 Table 5-67. Summary of Mercury Fluxes Measu red from Landfill Facilities (after Xin and Gustin, 2005)

Substrate Type Number of Measurements on

Substrate Surface Range of Flux Measurements, ng/m 2 /hr Fly Ash 97

− 0.2–4.9 Vegetated Fly Ash with Soil Cover 9 0.9–33.4 Wet FGD Material + Mill Rejects 12 6.9–15.9

Wet FGD Material 61 0.3–2.5 Stabilized Wet FGD Material (with fly ash) 61 0.7–22.2

Natural Grasslands (background soil) 9

− 0.1–0.3

Agricultural Land 9 0.0–2.3

exceptionally high mercury mean emission rate (33.3 ng/m 2 /hr). The high flux rate value was not used in further calculations because the sampling location was close to an active road and potentially had contaminated road dust or other road-related deposits to the soil surface.

For the wet FGD material substrate, whic h was disposed of in an ash pond, mercury

emission flux was low

. The mean daytime mercury flux was 1.3 ± 0.8 ng/m 2 /hr and the mean nighttime mercury flux was 0.3 ± 0.3 ng/m 2 /hr. The low emission for the saturated FGD material, as compared to that for wet but not saturated material, is similar to that reported for

soils. Soils that are saturated have been shown to have low Hg emissi ons, but as soils dry, emissions increase (Gustin and Stamenkaric, 200 5). Mercury emission rates were highest from

the wet FGD materials.

For the stabilized wet FGD material (with fly ash) substrate, mercury flux varied significantly among measurement sites. Low mean mercury emission fluxes were measured at three sites (0.7–4.8 ng/m 2 /hr), while higher mercury emission values were observed at two sites (10.9–22.2 ng/m 2 /hr). The average daytime mercury flux was 11.5 ± 12.7 ng/m 2 /hr, and the average nighttime mercury flux was 10.9 ± 7.2 ng/m 2 /hr. The high variability of the data may be explained by the inhomogeneity of the wet FGD mate rial and fly ash mixtur e within the disposal site. No correlation between mercury flux and light was observed for this substrate. The windy

conditions when flux measurements were made on this substrate could al so have affected the mercury flux (Gustin et al., 1997).

Mercury emissions were also measured for two types of soils in the surrounding area: a natural soil not obviously imp acted by agriculture and a field. Mean flux ranged from

− 1–2.3 ng/m 2 /hr during the day.

Observations can be summarized as follows:

• Wet FGD material (with fly ash) exhibited the highest release.84 • Fly ash substrates exhibited very low me rcury emissions, with the exception of one potentially contaminated site.

• Fly ash, vegetated fly ash with soil cover, and wet FGD material exhibited low mercury emissions similar to the background natu ral grasslands and agricultural land.

• No strong correlation was observed be tween mercury flux and total mercury

concentration for the substrates evaluated.

The flux measurements were used to calc ulate an annual mercury release for each substrate, and those calculated releases are noted in Table 5-68 (Xin and Gustin, 2005). Based on calculations for this field site, about 20.6 g Hg/yr would be emitted from the five sites evaluated. For the same area of natural grassland, 0.4 g Hg/yr would be emitted, and 5.5 g Hg/yr would be emitted from the agricultural land.

Data from this work were compared with data collected from a CCB landfill facility in the eastern United States (Gustin and Ladwig, 2004) and a CCB landfil l located in th e Great Lakes

area of the United States. The eastern site was a bituminous fly ash landfill visited in October

2002 and the Great Lakes site was a blended bitu minous–subbituminous fly ash landfill visited in October 2003. The comparison data are shown in Table 5-69. Assuming a disposal area of 100,000 m 2 for all substrates at all disposal sites, annual mercur y emissions were calculated.

These are also included in Table 5-69.

The highest calculated mercury releases were noted for the lignite-based stabilized wet FGD material (with fly ash) and the wet FGD material + mill rejects. The lignite-derived barren fly ash had the highest mercury flux compar ed to bituminous and blended bituminous– subbituminous fly ash. Vegetated fly ash from th e eastern United States and Great Lakes area acted as a mercury sink (mercury flux <0), whereas vegetated fly ash at the lignite site indicated

Table 5-68. Summary of Scaling of Emissions Using Field Site Data (Xin and Gustin, 2005)

Sample Type Area 1 , m 2 Mean Flux, ng/m 2 /hr Total Annual Flux, g/yr Barren Fly Ash 141,642 1.1 1.4 Vegetated Fly Ash 56,657 1.1 0.5 Stabilized Wet FGD 141,642 11.2 13.9 Unstabilized Wet FGD 141,642 0.8 1.0 Wet FGD + Mill Rejects 40,469 10.9 3.9
TOTAL 522,050 - 20.6

Natural Grassland (background soil) 522,050 0.1 0.4

Agricultural Land 522,050 1.2 5.5

1 Areas was estimated according to the field site landfill map.85 Table 5-69. Comparison of Scaling of Hg Flux Using In Situ Data from Three Landfill Sites (Field site examined in this report, one site in Eastern Unit ed States, and one site in the

Great Lakes area of the United Stat es. Area used for scaling is 100,000 m 2 for each substrate. Mean flux was the average flux obta ined from daytime and nighttime flux [Xin and Gustin, 2005])

Location Coal Type Sample Type Mean Flux, ng/m 2 /hr Total Annual Flux, g/yr Barren fly ash 1.1 0.9 Vegetated fly ash 1.1 0.9

Stabilized wet FGD 11.2 9.8

Unstabilized wet FGD 0.8 0.7 Wet FGD + mill rejects 10.9 9.5 Natural grassland 0.1 0.1 Field Site

Described in This Report Lignite

Agricultural land 1.2 1.1 Barren fly ash

− 0.2

− 0.2 Soil-covered fly ash

− 9.5

− 8.3 Eastern United

States Bituminous

Vegetated fly ash

− 0.2

− 0.2 Barren fly ash 0.9 0.8 Vegetated fly ash

− 0.1

− 0.1 Great Lakes Area

in United States Blended

bituminous and

subbituminous Soil 0.5 0.5

a release of mercury. Xin et al. (2006) provides a detailed discu ssion of data collected in the eatstern United States and the Great Lakes region.

5.6.1.3 Measurement of Mercury in CCB Landfill Air by the EERC

Using the method described in the experime ntal section, sampli ng was performed at

several locations at the CCB landfill site. Measurem ents were taken at locations near the UNR mercury flux measurement locations when possibl e. Results generated by the EERC at storage sites for elemental mercury captured on gold tr aps and organomercury captured on Supelco CarbotrapTM-containing tubes are outlined in Ta ble 5-70. The results are reported as ng/m 3

, which refers to the amount of mercury capture d on traps while a determined amount of CCB landfill air was drawn through the tubes.

The measured CCB landfill air mercury values were low and generally comparable to air

measurements made at locations in the natura l grasslands, which serv ed as an undisturbed background site. The highest elemental mercury concentrations were m easured near the wet FGD material + mill rejects. Most of the other el emental mercury air measurements were similar.

The measured organomercury concentrations , however, were all very low, with the stabilized wet FGD material (with fly ash) sampling location yieldi ng the highest reading.86 Table 5-70. Average CCB Landfill Mercury Re adings and Standard Deviation, ng/m 3 (field blanks were subtracted)

Substrate Type Elemental Mercury n Organomercury n Calculated Total Mercury Fly Ash 1.021 ± 0.238 4 0.052 ± 0.038 2 1.073 Vegetated Fly Ash with Soil

Cover 0.616 ± 0.277 4 0.019 ± 0.026 2 0.635

Wet FGD Material + Mill

Rejects 1.459 ± 0.995 4 0.006 ± 0.002 2 1.465

Wet FGD Material 0.954 ± 0.413 4 0.045 ± 0.042 2 0.999 Bottom Ash/Mill Rejects + Wet

FGD Material 0.541 ± 0.193 4 0.023 ± 0.011 2 0.564

Stabilized Wet FGD Material

(with fly ash) 0.849 ± 0.378 4 0.354 ± 0.476 2 1.203

Natural Grasslands (background

soil) 0.640 ± 0.270 4 0.017 ± 0.004 2 0.657

In Table 5-70, a calculated total mercury for air at each location is included. Using this value, the measurements can be listed from highest to lowest:

Wet FGD material + mill rejects > Stabilized wet FGD material (with fly ash) > Fly ash

> Wet FGD material > Natural grasslands (background soil) > Vegetated fly ash with soil cover > Bottom ash/mill rejects + wet FGD ma terial (sample not evaluated by UNR)

In comparison, the mercury flux measur ements performed by UNR resulted in the following indication of high to low me rcury associations by substrate:

Wet FGD material + mill rejects > Stabilized wet FGD material (with fly ash) > Fly ash > Agricultural land (sample not evaluated by EERC)

= Wet FGD material > Vegetated fly ash with soil cover > Natural grasslands (background soil)87 5.6.2 Alternate Field Task

The Phase 2 field investigation (alternate field task) was deve loped in response to project sponsor input on results of Field Task 1. It was agr eed that a useful addition to this task would be to evaluate the impact of in teraction between soil and CCBs on mercury release from CCBs, especially since CCBs are used in numerous soil app lications. The interaction of greatest interest was that caused by inherent microbiological or ganisms typically found in soils. The CCB–soil laboratory experimental apparatu s was designed to evaluate mi crobiologically mediated mercury release from CCB–soil mixtures, analogous to u tilization management pr actices in the field. Elemental mercury and organomercury release measurements were evaluated. Fundamental

characterization data of the soil used are in Appendix T.

The results of the elemental mercury release are shown in Ta ble 5-71, reported in a manner similar to the long-term ambient-temperature re lease experiments for CCBs. The total mercury

content of the CCB–soil mixtures was not measur ed; therefore, a calculation based on the total mercury content of the separate components and th e mixture percentage is given in Table 5-71. Each sample bottle had a blank bottle measuremen t of elemental mercury prior to introduction of the CCB–soil mixture. Sorption or release of el emental mercury was determined by subtracting

the blank value from the measurements. The calc ulations in the columns labeled “Cumulative % Elemental Hg Sorption or Release from Mix” and “Years to Release 100% Elemental Hg at

Measured Rate” are based on the calculated mixt ure total mercury content. Paired samples (Samples 05-038 and 05-025) are highlighted; these samples are from the larger sample set of paired lignite fly ash samples.

During the duration of the expe riment, the research team wa s unable to collect replicate data for two samples (Samples 05-038 and 06- 014) because of apparatus difficulties that developed.

The results show that the soil–peat moss mixtur e (only one data point) used in this task sorbed elemental mercury. The CCB–soil mixtures exhibited low levels of elemental mercury release, with the exception of one replicate. On average, ov er 100,000 years of air movement over the CCB–soil mixtures is required to release all mercury from the system. Samples that had AC present released lower percentages of elem ental mercury than thos e without AC present, even though the total mercury wa s higher in the samples with AC , especially those collected after the primary PCD. On average, the samples with AC present released mercury an order of magnitude lower percentage than the sample from a similar coal source without AC. However, as shown in Appendix U, the measured elemental me rcury release rate was higher for the fly ash + AC (post-primary PCD) samples. The paired sa mple set provided a good comparison of a fly ash sample without and with AC present.

Organomercury results are reported in Table 5-72. No organomercury blank value measurements were performed sinc e preparation of the experiment al vessel (heating to >500°C) was expected to eliminate any organomercury fro m the container. Therefore, the organomercury collected from the soil-only bottle served as th e blank for the experiment. This allowed for a determination of the impact of each CCB in each CCB–soil mixture.88Table 5-71. Alternative Field Task (CCB–soil) Elemental MercuryResults Summary. Positivevalues indicate release andnegative values indicate sorption of elemental mercury. Duplicate bottles are represented.Replicate 1 Replicate 2ID No. Sample Type Coal TypeCalculatedMixtureTotal Hg,μg/gCumulativeNo. DaysCumulative% ElementalHg Sorptionor Releasefrom MixYears toRelease 100%Elemental Hgat MeasuredRateCumulative% ElementalHg Sorptionor Releasefrom MixYears toRelease 100%Elemental Hgat MeasuredRate04-003 Fly ash Easternbituminous0.190 167 0.00105 43,693 0.000590 77,51704-054 Fly ash + AC(post-primaryPCD)Easternbituminous3.60 167 0.000288 158,678 0.000295 154,92804-029 Fly ash PRBsubbituminous0.106 167 0.00529 8,650 0.00414 11,05603-060 Fly ash + AC(pre-primaryPCD)PRBsubbituminous0.426 166−0.000195 NA – sorbing 0.000123 368,45505-0381Fly ashLignite0.07401660.0026617,075NQ2NQ05-025Fly ash + AC(post-primaryPCD: high ash)Lignite2.581670.000205222,9680.000266172,31905-009 FGD gypsum Easternbituminous0.0598 166 0.00181 25,189 0.00101 45,22106-014 Soil None 0.0666 166 NQ NQ−0.00205 NA – sorbing1Shading indicates paired samples.2Not quantitated.89Table 5-72. Alternative Field Task (CCB–soil) Organomercury Results Summary.Results are expressed as a comparison tothe soil used as blank. Positive values indicate release, and negative values indicate sorption of organomercury. Duplicatebottles are represented.Replicate 1 Replicate 2ID No. Sample Type Coal TypeCalculatedMixtureTotal Hg,μg/gCumulativeNo. DaysCumulative %OrganomercurySorption orRelease fromMixtureCompared to SoilYears to Release100%Organomercuryat Measured RateCompared to SoilCumulative %OrganomercurySorption orRelease fromMixtureCompared to SoilYears to Release100%Organomercuryat Measured RateCompared to Soil04-003 Fly ash Easternbituminous0.190 168 0.00134 34,465 0.000977 47,39604-054 Fly ash + AC(post-primaryPCD)Easternbituminous3.60 171−0.0000123 NA – below soilrelease−0.0000207 NA – below soilrelease04-029 Fly ash PRBsubbituminous0.106 169−0.000531 NA – below soilrelease−0.000481 NA – below soilrelease03-060 Fly ash + AC(pre-primaryPCD)PRBsubbituminous0.426 167−0.000248 NA – below soilrelease−0.000261 NA – below soilrelease05-0381Fly ashLignite0.074168−0.00124NA – below soilreleaseNQNQ05-025Fly ash + AC(post-primaryPCD: high ash)Lignite2.581720.00002971,588,470−0.0000109NA – below soilrelease05-009 FGD gypsum Easternbituminous0.0598 168−0.000418 NA – below soilrelease0.00358 12,8581Shading indicates paired samples.90 The results indicated that more organomercu ry was released from four of 13 replicate

CCB–soil mixture bottles than from the soil-only bottle. All organomercury re leases were low. Again, the samples with AC generally exhibite d a lower-percentage release of mercury than those without AC present, although the difference was not as consistent as that observed for elemental mercury releases. The fly ash alone from th e paired sample set released a lowerpercentage organomercury by two orders of magnit ude when compared to the fly ash + AC in the paired set.

The CCB sample elemental mercury vapor profiles for this task versus long-term ambienttemperature release and microbiologically mediat ed vapor-phase trans port task profiles are provided in Table 5-73. The FGD gypsum sample evaluated in this task (Sample 05-009) exhibited elemental mercury release whether analy zed alone or when mixed with soil. Generally, fly ash samples that exhibited an overall elem ental mercury sorption in the long-term ambienttemperature release experiment released mercury in the alternate field task when combined with soil. It was hypothesized by the project team during performa nce of the microbiologically mediated mercury release experiments that carb on (either unburned or ac tivated) would provide a source of food for the microbes present in the system and might promote release of mercury. These limited results sup port that hypothesis.

5.7 Data Reduction and Interpretation

The standard analysis techniques used in the project indicate acceptable performance criteria. The repeatability of the data was within the expected ±20%, with the exception of the data produced in the microbiological experiments. In this case, the experime nts are still a work in progress, with much improvement yet needed on the technique. This is nearing completion. Despite more variability than had been hoped for, the data still proved useful.

Data reduction and interpretation was performe d on a task basis for the release and field tasks, incorporating information from the method and sample selec tion tasks. Data interpretation incorporated information from real-world ash management scenarios in an attempt to draw conclusions on Hg ATE releases und er disposal and use scenarios.

6.0 CONCLUSIONS AND RE COMMENDATIONS

This project achieved its stated objectives, an d based on the results of the laboratory and field experiments conducted in this project, the followi ng conclusions were drawn:

• Results for “paired” baseline and test fl y ash and FGD–SDA samp les indicated that total mercury content was higher in the te st samples. Test samples contained AC injected as mercury sorbent with one excep tion, where an EA only was injected. The higher total mercury content was also genera lly noted for all fly ash samples collected from systems without mercury emission cont rols as compared to fly ash that was collected from systems with mercury emission controls in place. No similar trend was noted for the limited nonpaired FGD–SDA samples.91Table 5-73. Overall Elemental Mercury Vapor Profiles in Noted TasksLong-Term AmbientTemperature ReleaseAlternateField TaskMicrobiologicallyMediated VaporPhase TransportID No. Sample Type Coal TypeTotal MercuryContent, μg/g LOI, % CCB OnlyCCB–SoilMixture CCB in Buffer04-003 Fly ash Easternbituminous0.685 8.45 NT Release Higher release underaerobic conditions04-054 Fly ash + AC (postprimary PCD)Easternbituminous17.7 18.6 Sorption Release NT04-029 Fly ash PRBsubbituminous0.261 0.48 Sorption Release NT03-060 Fly ash + AC (preprimary PCD)PRBsubbituminous1.86 2.37 Release Sorption Higher release underaerobic conditions05-0381Fly ashLignite0.1040.22SorptionReleaseNT05-025Fly ash + AC (postprimary PCD: highash)Lignite12.63.19SorptionReleaseNT05-009 FGD gypsum Easternbituminous0.032 1.92 Release Release NT06-014 Soil None 0.067 44.2 NT Sorption NT1Shading indicates paired samples.92• The total selenium content of “paired” baseline and test fly ash samples with postprimary PCD ACI was higher for the test sample s than the baseline samples. This trend was not noted for “paired” samples with pre-primary PCD ACI or generally for the nonpaired samples.

• Total concentrations of arsenic, cadmium, chromium, lead, and nickel were similar for all fly ash samples and FGD–SDA samples co llected from systems with or without mercury emission controls in place. This was true for “paired” and nonpaired samples.

• Direct leaching tests indicated that mercur y was not readily leached from fly ash or FGD materials. 87% of samples leached had at least one leachate mercury concentration below the 0.01 μg/L analytical reporting limit. Mercury leac hate concentrations did not correlate to total mercury concentrations. In particular, the samples with the highest total mercury content showed no detectable leachate mercury. These conclusions were consistent for both paired and nonpaired samples.

• When exposed to ambient-temperature air in laboratory experiments, fly ash samples

either released or sorbed small amount s of mercury. Samples containing unburned carbon or AC tended to sorb mercury in ambi ent-temperature vapor-phase experiments. For fly ash samples that release mercury, the rate of release gene rally decreased with time. For those that sorbed mercury, the rate of sorption was generally increased over the duration of the experiments. All wet F GD material, including FGD gypsum released mercury in ambient-temperature laboratory experiments. When releases were noted, they were extremely low, both in total re leased over extended la boratory tests and in rate released. Laboratory data indicated that the potent ial for ambient-temperature vapor-phase mercury releases from CCBs is unlikely to impact atmospheric mercury loading.

• Mercury was not released to the vapor-phase at temperatures below 250°C in elevatedtemperature experiments. For some samples, the presence of AC with fly ash increased the temperature at which mercury was released when exposed to el evated temperature, but these samples were too limited in number to draw a final conclusion on the effect of AC on the initial release temperature for fl y ash + AC. For most fly ash samples with and without AC present, all mercury was rel eased from the sample before the sample

reached 750°C. Interferences from sulfur compounds precluded the use of the method developed for FGD materials.

• Under microbiologically mediated conditi ons, elemental and or ganomercury were released both to the vapor phase and the l eachate. While the levels of elemental and organomercury were low in both leachate and vapor, more elemental mercury was released. Fly ash samples with high pH valu es did not support microbial growth because the buffering capacity of the samples was too great. Samples of FGD material released hydrogen sulfide so mercury releases coul d not be quantitated. Very low amounts of elemental and organomercury releases were measured from soil–CCB mixtures in simulated field experiments. The results were consistent between the two experiments.93 • Field experiments evaluated vapor-phase releases at a CCB disposal site. Results indicated low-level vapor-phase mercury rele ases, as was generally noted in laboratory experiments for lignite fly ash samples. Rel eases from FGD materials were noted both in laboratory and field measurements.

• Laboratory methods were developed to ev aluate the potential for mercury releases

under several release mechanisms.

Based on the results of this project, th e following recommendations were made:

• Further work is needed on fly ash + noncar bon sorbents, fly ash + EAs, and fly ash +

carbon and noncarbon sorbents with EAs.

• Further investigations are required to better quantitate mercury releases from FGD

materials and understand the mechanisms of release.

• Highly alkaline fly ash samples with or wit hout sorbent or additives do not need to be subjected to microbiologically mediated releas e experiments. Future work could include samples of alkaline fly ash mixed with ot her CCBs such as FGD material that might provide adequate neutralizati on to support microbial growth.

7.0 REFERENCES

ADA-ES, Inc. Field Test Program to Develop Comprehensive Design, Operating, and Cost Data for Mercury Control Systems. Final Site Report for Pleasa nt Prairie Power Plant Unit 2 Sorbent Injection into a Cold -Side ESP for Mercury Control ; Final Report; DOE Report No. 41005R12; May 2003.

ASTM International. Standard Test Method fo r Major and Minor Elements in Coal and Coke Ash by X-Ray Fluorescence. D4326-04, 2004a.

ASTM International. Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete. C311-04, 2004b.

ASTM International. Standard Test Method for Sh ake Extraction of Solid Waste with Water. In Annual Book of ASTM Standards; Section 11: Water and Environmental Technology, ASTM D3987-06, 2006.

Carey, T.R.; Richardson, C.F.; Chang, R. Stabi lity of Mercury Captured on Sorbent Surfaces. Presented at the Air and Waste Manage ment Association 92nd Annual Meeting and Exhibition, St. Louis, MO, June 20–24, 1999.

Energy & Environmental Research Center. Me rcury Information Clearinghouse. Quarter 4 – Rerelease of Mercury from Coal Combustion By-Products, Oct 2004.94 Energy & Environmental Research Center. Me rcury Information Clearinghouse. Quarter 9 – Mercury Information Cleari nghouse Final Report, Dec 2005.

Energy Information Administration. Annual Energy Outlook 2004 with Projections to 2025 ; U.S. Department of Energy: Washington, DC, 2004.

Gasiorowski, S.; Bittner, J.; Mackay, B.; Whitlo ck, D. Applications of Carbon Concentrates Derived from Fly Ash. In Proceedings of the 15th International American Coal Ash Association Symposium on Management & Us e of Coal Combustion Products (CCPs) ; St. Petersburg, FL; Jan 27–30, 2003.

Gustin, M.S.; Ladwig, K. An Assessment of the Significance of Mercury Release from Coal Fly

Ash. J. Air Waste Manage. Assoc

. 2004

, 54 , 320–330.

Gustin, M.S.; Stamenkovic, J. Effect of Wateri ng and Soil Moisture on Mercury Emissions from

Soils. Biogeochem. 2005, 76 (2), 215–232.

Gustin, M.S.; Taylor Jr, G.E.; Maxey, R.A. Ef fect of Temperature and Air Movement on the Flux of Elemental Mercury from Substrate to the Atmosphere. J. Geophysic. Res. 1997

, 102

, 3891–3898.

Hassett, D.J. The Synthetic Groundw ater Leaching Procedure. In Encyclopedia of Environmental Analysis and Remediation ; Meyers, R.A., Ed.; John Wiley and Sons: New York, 1998; pp

4797–4803.

Hassett, D.J. Scientifically Valid Leaching of Coal Conversion Solid Residues to Predict Environmental Impact. In Proceedings of the Trace Element Transformations in Coal-Fired Power Systems Workshop; Scottsdale, AZ, April 19–22, 1993; Special Issue of Fuel

Process. Technol

. 1994, 39 (1–3), 445–459.

Hassett, D.J.; Moe, T.A. Oxidation of North Dakota Scr ubber Sludge for Soil Amendment and Production of Gypsum ; Final Report; EERC Publi cation 97-EERC-10-05; Energy & Environmental Research Center: Grand Forks, ND, Oct 1997.

Hassett, D.J.; Heebink, L.V. Environmental Evaluation for Utilization of Ash in Soil
Stabilization ; Final Report for U.S. Department of Energy, Energy & Environmental Research Center: Grand Forks, ND 2002.

Hassett, D.J.; Heebink, L.V. Qualifying CCBs for Agricu ltural Land Application ; Final Report Prepared for the Combustion Byproducts Recy cling Consortium (CBRC); EERC Publication 2007-EERC-02-07; Energy & Environmental Research Center: Grand Forks, ND, Feb.

2007.

Hassett, D.J.; Heebink, L.V.; Gallagher, J.R. ; Pflughoeft-Hassett, D.F.; Laudal, D.L. Stability of Mercury in Coal Combusti on By-Products and Sorbents ; 2002 Annual Report of the Center for Air Toxic Metals, organized and administer ed through the Univer sity of North Dakota95 Energy & Environmental Resear ch Center, for U.S. Environmental Protection Agency Contract No. R 827649-01; 2002; pp 69–76.

Engle, M.A.; Gustin, M. S.; Zhang, H. 2001 Quantifying Natural Source Mercury Emissions from the Ivanhoe Mining Distri ct, North-Central Nevada, USA, Atmospheric Environment

, 35; 2001; 3987–3997.

Hassett, D.J.; Heebink, L.V.; Gallagher, J.R.; Laudal, D.L.; Pflughoeft-Hassett, D.F. Stability of Mercury in Coal Combusti on By-Products and Sorbents ; 2003 Annual Report of the Center for Air Toxic Metals, organized and administer ed through the Univer sity of North Dakota Energy & Environmental Resear ch Center, for U.S. Environmental Protection Agency Contract No. R 827649-01; 2003; pp 103–115.

Hassett, D.J.; Pflughoeft-Hassett, D.F.; Heebink, L.V. A Review of the Current State of the Science Related to Rerelease of Me rcury from Coal Combustion Products ; Final Report for Utility Solid Waste Activ ities Group; EERC Publication 2004-EERC-11-01; Energy &

Environmental Research Center : Grand Forks, ND, Nov 2004.

Hassett, D.J.; Pflughoeft-Hassett, D.F.; Heebin k, L.V. Leaching of CCBs: Observations from

over 25 Years of Research. 2003 International As h Utilization Symposium, Special Issue of

Fuel 2005, 84 (11), 1378–1383.

Heebink, L.V.; Hassett, D.J. Release of Mercury Vapor from Coal Combustion Ash. J. Air Waste Manage. 2002

, 52 (8), 927–930.

Heebink, L.V.; Pflughoeft-Hassett, D.F.; Hassett, D.J.; Zacher, E.J.; Eylands, K.E. Mercury and Air Toxic Element Impacts of Coal Com bustion By-Product Disposal and Utilization ; 2004 Annual Report of the Center for Air Toxic Me tals, organized and administered through the University of North Dakota Energy & Envi ronmental Research Center, for U.S. Environmental Protection Agency Contract No. R 827649-01; 2004; pp 115–131.

Heebink, L.V.; Pflughoeft-Hassett, D.F.; Hassett, D.J.; Buckley, T.D.; Zacher, E.J. Laboratory Assessment of the Impact of Carbon-Based So rbents on the Management of Fort Union Lignite CCBs; In Proceedings of the 20th Symposium on Western Fuels ; Denver, CO, October 24–26, 2006.

Hower, J.; Rubel, A.; Mardan, S.; Perrone, R. Thermal Stability of Mercury Captured by Fly

Ash. Presented at the 19th Western Fuels Symposium, Billings, MT, October 12–14, 2004.

Keating, M.H.; Chaisson, J.M. The Fate of Merc ury on Coal-Fired Power Plants and Combustion Wastes. In Mercury in the Environment. In Proceedings of a Specialty Conference ; Air & Waste Management Association, Mi nneapolis, MN, Sept 15–17, 1999; pp 494–499.

Kosson, D.S.; van der Sloot, H.A.; Sanchez, F.; Ga rrabrants, A.C. An Integrated Framework for Evaluating Leaching in Waste Management a nd Utilization of Secondary Materials. Environ. Eng. Sci. 2002, 19 (3), 159–203.96 Laudal, D.L.; Gallagher, J.R.; Hassett, D.J.; Timpe, R.T. Stability of Mercury in Coal Combustion By-Products ; 2000 Annual Report of the Center for Air Toxic Metals, organized and administered through the University of North Dakota Energy &

Environmental Research Center , for U.S. Environmental Protection Agency Contract No. R 827649-01; 2000; pp 59–68.

Laudal, D.L.; Hassett, D.J.; Heebink, L.V.; Gallagher, J.R. Stability of Mercury in Coal Combustion By-Products ; 2001 Annual Report of the Center for Air Toxic Metals, organized and administered through the University of North Dakota Energy &

Environmental Research Center , for U.S. Environmental Protection Agency Contract No. R 827649-01; 2001; pp 51–60.

Lockert, C.A.; Zhou, Q.; Zhang, Y.; Nelson, S. Further Progress Towa rd Concrete-Friendly Mercury Sorbents. In Proceedings of Air Quality V: International Conference on Mercury, Trace Elements, SO 3 , and Particulate Matter ; Arlington, VA; Sept 2005.

Maroto-Valer, M.M.; Taulbee, D.N.; Hower, J. C. Novel Separation of the Differing Forms of Unburned Carbon Present in Fly Ash Us ing Density Gradient Centrifugation. Energy Fuels 1999a, 13 (4), 947–953.

Maroto-Valer, M.M.; Taulbee, D.N.; Schobert, H. H. Hower, J.C. Characterization of Differing Forms of Unburned Carbon Present in Fly Ash. In Proceedings of 1999 International Ash Utilization Symposium , Lexington, KY, Oct 18–20, 1999b.

Pavlish, J.H. Task 1.2 – Mercury Stability in the Environment ; Final Report for U.S. Department of Energy National Energy Technology Laborat ory; Energy & Environmental Research Center: Grand Forks, ND, July 1999.

Pflughoeft-Hassett, D.F.; Dockter, B.A.; Eylands, K.E.; Hassett, D.J. Survey and Demonstration of Utilization Potential of North Dakota Lignite Ash Resources ; Final Report; EERC Publication 1996-EERC-04-01; Energy & Environm ental Research Center: Grand Forks, ND, April 1996.

Pflughoeft-Hassett, D.F.; Dockter, B.A.; Hassett, D.J.; Heebink, L.V.; Solc, J.; Buckley, T.D. Demonstration of Coal Ash for Feedlot Surfaces ; Final Report; EERC Publication 2004- EERC-02-10; Energy & Environmental Resear ch Center: Grand Forks, ND, Feb 2004.

Regulatory Finding on the Emissions of Hazardous Air Pollutants from Electric Utility SteamGenerating Units. Fed. Regist. 2000, 65 (245), 79825–79831.

Sanchez, F.; Keeney, R.; Kosson, D.; Delapp, R. Characterization of Mercury-Enriched Coal Combustion Residues from Elect ric Utilities Using Enhanced Sor bents for Mercury Control ; EPA-600/R-06/008; Environmental Protec tion Agency: Washington, DC, Feb 2006.97 Schwalb, A.M.; Withum, J.A. The Evolution of Mercury from Coal Co mbustion Materials and By-Products. Presented at the Mercury Cont rol Technology R&D Program Review Meeting, Pittsburgh, PA, Aug 12–13, 2003.

U.S. Department of Energy National Ener gy Technology Laboratory. Updated Economic Analysis of Activated Carbon Injecti on, May 2007. http://www.ne tl.doe.gov/technologies/ coalpower/ewr/mercury/pubs/Phase_II_UP DATED_Hg_Control_Economic_Analysis.pdf.

U.S. Environmental Protection Agency. Fact Sheet, EPA Proposes Options for Significantly Reducing Mercury Emissions from Electric Utilities, Dec 15, 2003.

U.S. Environmental Protection Agency. Te st Methods for Evaluating Solid Waste: Physical/Chemical Methods (SW-846), Meth od 1311, Toxicity Characteristic Leaching

Procedure. 1992.

U.S. Environmental Protection Agency. Method 7471, Mercury in Solid or Semisolid Waste (Manual Cold-Vapor Technique). Test Methods for Evaluating Solid Waste, Physical/Chemical Methods,” EPA Publica tion SW-846, Third Edition, as amended by Updates I, II, IIB, III, and IIIB finalized in the Federal Register on June 14, 2005a.

U.S. Environmental Protection Agency. Me thod 6010, Inductively Coupled Plasma-Atomic Emission Spectrometry. Test Methods for Ev aluating Solid Waste, Physical/Chemical Methods,” EPA Publication SW-846, Third Editi on, as amended by Updates I, II, IIB, III, and IIIB finalized in the Federal Register on June 14, 2005b.

U.S. Environmental Protection Agency. Method 6020, Inductively Coupled Plasma – Mass Spectrometry. Test Methods for Evaluating Solid Waste, Physical/Chemical Methods,” EPA Publication SW-846, Third Edition, as amended by Updates I, II, IIB, III, and IIIB finalized in the Federal Register on June 14, 2005c.

Xin, M.; Gustin, M.S.; Ladwig, K. Laborator y Study of Air–Water–Co al Combustion Product (Fly Ash and FGD Solid) Mercury Exchange. Fuel 2006, 85 (16), 2260–2267.

Xin, M.; Gustin, M.S. Mercury Release from Coal Combustion Products (CCPs): North Dakota Field Study Report. In Appendix of Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilization ; Year 2 Final Report Prepared for U.S. Department of Energy; Cooperative Agreement No. DE-FC26-03NT41727, EERC Publication 2005-EERC-06-09; En ergy & Environmental Research Center: Grand Forks, ND, June 2005.

Ziemkiewicz, P.F. The Mine Water Leaching Procedure. In Proceedings of Regulation, Risk, and Reclamation with Coal Combustion By-Products at Mines: A Techni cal Interactive Forum ; U.S. Office of Surface Mining, Lexington, KY, April 13–14, 2005; pp 101–104.

# APPENDIX A

SAMPLE IDENTIFICATION FORMSAMPLE IDENTIFICATION FORM Mercury and Air Toxic Element Impacts of Coal Combustion Byproduct Disposal and Utilization

Company:

Station: Unit:

Contact Name (to relay data):

Date Sample Collected:

SYSTEM INFORMATION

BURNER TYPE

Pulverized Coal-Fired Cyclone

Stoker Fluidized-bed combustion (FBC)

Low-NO

x Burners

PARTICULATE COLLECTION Fabric Filter (FF) Electrostatic Precipitator (ESP) Cold Side

ESP Hot Side

ESP/Mechanical

FF/Mechanical

Other:

SO 2 CONTROL

None

Wet Flue Gas Desulfurizati on (FGD) (calcium based)

Lime

Limestone sorbents

Forced oxidation

Natural or in situ oxidation Dry FGD (calcium based) Spray Dryer Atomizer Wet FGD (alkali based) Dry FGD (alkali based)

Other:

AMMONIA-BASED SYSTEM

None Ammonia Injection Selective Catalytic Reduction Selective Noncatalytic ReductionMERCURY CONTROL

None Carbon Injection Injection Rate: Noncarbon Sorbent Injection Injection Rate:

Modified FGD

Fine Particulate Control Fly Ash from Carbon Removal Technologies

Other:

SAMPLE INFORMATION

FUEL TYPE

Bituminous

Subbituminous Lignite

Bituminous–Subbituminous Blend: % Bituminous/ % Subbituminous Subbituminous–Lignite Blend: % Subbituminous/ % Lignite

Oil

Other

SAMPLE TYPE(S) Fly Ash

FGD

Blend: % / %

Filtrate

Other:

COLLECTION POINT(S)

FF

ESP Field Specify: ESP Hopper Specify:

Silo

Pond/Landfill

Other:

OTHER INFORMATIONProject ID Sample Type Collection Point Other Description03-321EXAMPLEFly AshESP Row 2Composite 03/21/03–04/02/03; ActivatedCarbon Injection 5 lb/MMacfReturn this form and samples to: lheebink@undeerc.orgLoreal Heebink Phone: (701) 777-5116Energy & Environmental Research Center Fax: (701) 777-518115 N 23rd StreetGrand Forks, ND 58203

# APPENDIX B

DRAFT STANDARD METHOD FOR SYNTHETIC

GROUNDWATER LEACHING PROCEDURE

# APPENDIX A

DRAFT ASTM STANDARD METHOD FOR

SYNTHETIC GROUNDWATER LEACHING

PROCEDUREDRAFT

1 DRAFT ASTM STANDARD METHOD FOR

SYNTHETIC GROUNDWATER LEACHING PROCEDURE

1. Scope

1.1 This method determines the leachability of constituents in wastes, products, or materials using a leaching solution designed to simulate leachate anticipated in field conditions. The method allows for prediction of changes in leachability brought about as a result of the formation of secondary hydrated phases and new minerals through interaction of the waste and water over extended periods of time.

1.2 his method consists of the agitation of waste and a synthetic groundwater solution over an extended period of time (greater than 60 days) with sampling at regular intervals.

1.3 This method allows a comparison of maximum leachate concentration with actual concentrations of leachate at time intervals of from 18 hours to 2 months or greater. The method allows for determination of mass of analyte mobilized based on a leachate concentration and percent of total element leached and provides information to estimate leachate concentration trends with respect to time.

1.4 This method may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of whoever uses this method to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

2. Applicable Documents

2.1 American Society for Testing and Materials (ASTM) Standards: D1129 Definitions of Terms Relating to Water D1193 Specification for Reagent Water

D3987 Shake Extraction of Solid Waste with Water D2216 Method for Laboratory Determination of Moisture Content of Soils

2.2Toxicity Characteristic Leaching Procedure (TCLP) EPA Method 1311

3. Definitions

3.1 For definitions of terms in this test method, see Definitions D1129.

3.2 Ettringite: Ettringite is a mineral having the nominal composition Ca 6 Al 2 (SO 4 ) 3 (OH) 12 ·26H 2 O. Ettringite is also the family name for a series of related compounds as is the case for many mineral families. Ettringite has characteristic structural features that are fairly unique. The structure comprises of calcium aluminate columns {Ca 6 Al 2 (OH) 12 24H 2 O} 6+ with the channels between these columns containing the other components, which include an oxyanion such as sulfate with hydroxide and water {(SO 4 ) 2-4 (OH) 0-4 (H 2 O) 0-6 } 6- . Ettringite is unique in that several elements that exist as oxyanions can substitute for the sulfate in th e structure. These elements include but are not limited to arsenic, boron, chromium, molybdenum, selenium, and vanadium. Ettringite is known to form in the hydration of low-rank coal conversion solid residuesDRAFT

2 (CCSRs) and in CCSRs from advanced coal combustion processes such as fluidized-bed combustion (FBC) and limestone injection modified burner (LIMB).

3.3 Synthetic Groundwater: Synthetic groundwater as used in this application refers to a solution prepared in the laboratory containing the major geochemical parameters that would be found in water likely to contact the disposed CCSR. In the case of rainwater contact, this solution would be Type IV water, while with groundwater, a typical solution might contain calcium, magnesium, sodium, sulfate, and bicarbonate. Groundwater collected at the site of disposal could also be used, although if that were the case, corrections would have to be made for concentrations of trace elements already present in the water. It has been found with most CCSRs that it is the CCSR that regulates the equilibrium concentrations of major constituents in a synthetic groundwater leaching procedure; thus the inclusion of major geochemical constituents of actual groundwater may be unnecessary in many cases.

4. Significance and Use

4.1 This test is intended as a means for determining the mass of analyte readily mobilized by leaching with groundwater and also provides a means of determining the trend of leachate concentration change, if applicable. This test is intended for use with CCSRs

and other materials formed under conditions of high temperature. The long-term nature

of the test allows the determination of cha nges in concentrations of leached constituents as materials react with water to form secondary hydrated phases and other materials not present in the original material.

4.2 This test method is not intended to provide an accurate means of determining actual leachate concentrations under field conditions. The test does provide information about leaching under field conditions, however, and is useful in predicting the mobility of leachable constituents of CCSRs. The information provided from this test is an estimation of the mass of analyte that can be solubilized and trend of concentration change with respect to time. It should be noted that not all analytes will increase in concentration to an equilibrium level. Numerous elements, especially those trace elements that exist as oxyanions in aqueous solution, can exhibit a decrease in solution concentration after an initial and normally rapid increase in concentration. Additionally, major constituents can change solution concentration in a manner that would not be predicted on the basis of solubility calculations based on common mineral types, especially in CCSRs that form ettringite.

4.3 Since CCSRs are produced under conditions of high temperature, reactions with water during leaching can be expected. If these reactions produce ettringite, the concentrations of analytes present in solution as oxyanions can be expected to decrease with respect to time as ettringite forms. Other mineral formation can be expected to control leachate concentrations of additional analytes in ways not expected from simple solubility calculations based on the composition of ash before leaching. Additionally, the formation of secondary hydrated phases can be expected to affect the concentrations of major components.DRAFT

3 5. Apparatus

5.1 For a complete description of the apparatus, see ASTM Standard Test Method for ShakeExtraction of Solid Waste with Water. Any apparatus that can provide conditions of endover-end agitation at 30 plus or minus 2 rpm as specified in the protocol for the TCLP can be used in this procedure.

6. Reagents

6.1 Purity of Reagents – Reagent-grade chemicals can be used, provided they do not contain appreciable amounts of elements to be determined in the extraction test. Reagents must be of sufficient purity so they do not interfere with the accuracy of the test or introduce bias in the results of analyses of leachates.

6.2 Purity of Water – Unless otherwise indicated, references to water shall be understood to mean Type IV reagent water at 18° to 27°C (Specification D1193). The method by which the Type IV water is prepared (distillation, ion exchange, reverse osmosis, etc.) should remain constant throughout the test.

6.3 Synthetic Groundwater – Synthetic groundwater is a leaching solution containing the major geochemical parameters important to groundwater likely to contact disposed CCSRs. As previously stated, in the case of CCSRs disposed above the water table and where the likely water to contact the disposed materials is rainwater, Type IV water can be used as the leaching solution. Where the water likely to contact disposed material is highly mineralized, either a sample of the water itself or a synthetic mixture prepared in the lab will be used. A typical North Dakota synthetic groundwater can be prepared by dissolving 0.50 grams of sodium sulfate and 1.00 grams of sodium bicarbonate in one liter of Type IV water. The analysis of this solution is as follows:

Na 436 mg/L

SO 4 338 mg/L

HCO 3 726 mg/L pH 8.3–8.7

This sodium sulfate bicarbonate buffered water is typical for central and western North Dakota. Used for leaching low-rank coal ash, calcium was omitted since the ash itself ultimately

determined the final calcium concentration.

Other formulas for synthetic groundwater can be prepared as needed for site-specific conditions. Care is required when preparing fo rmulations containing calcium and magnesium that carbonates not be allowed to precipitate. This can be overcome by adding the reagents in the proper order, being certain that all carbonate is buffered to bicarbonate before adding the calcium and magnesium. Since sulfuric acid is used for sulfate and acid buffering, having excess sulfuric acid acidity will ensure this. A lo tus spreadsheet is available for the calculations necessary to select reagents for synthetic groundwater formulations, but with the limited components, the calculations can also be easily carried out manually.DRAFT

4 7. Sampling

8. Sample Preparation

8.1 For sample preparation, see D3987 Standard Test Method for Shake Extraction of Solid

Waste with Water.

9. Procedure

The laboratory protocol is similar to the U.S. Environmental Protection Agency (EPA) TCLP

and ASTM D3987 Standard Test Method for Shake Extraction of Solid Waste with Water. The primary difference is in the selection and preparation of the extraction fluid and the extension of test equilibration time over the prescribed 18-hour period. The long-term leaching aspect of this test is especially important since CCSRs can form secondary hydrated phases upon contact with water that can have a profound impact on leachate concentration of trace elements, especially elements that tend to exist as oxyanions in solution. The formation of secondary hydrated phases is known to take time, depending on the source of reactants in the leaching system. Time for complete formation of secondary hydrated phases can be from days to months. The test is not intended to carry the leaching to complete equilibrium but rather to extend the leaching time long enough for prediction of leachate concentration trends. For specifics related to the test, see D3987 Standard Test Method for Shake Extraction of Solid Waste with Water, or EPA Method 1311 TCLP, Federal Register, Vol 55, No. 126, June 29, 1990.

9.1 Record the physical description of the sample to be tested including particle size as

known.

9.2 Solids Content – Determine the solids content of the sample as described in D3987 Standard Test Method for Shake Extraction of Solid Waste with Water, Sections 9.2.1 through 9.2.4.

9.3 Shake Procedure – Prepare the apparatus and begin the test as described in D3987 Standard Test Method for Shake Extraction of Solid Waste with Water, Sections 9.4 through 9.7, except that multiple shake test containers are prepared for each sample, the number depending on the duration of long-term leaching. Leaching solution shall be prepared as described in the following section. Long-term leaching intervals for this procedure are 18 hours, 1 week, 1 month, and 2 months. Longer times can be used ifdesired, although trends are usually identified within the 60-day duration of this longterm leaching procedure. An alternative to the use of 2 liters of leaching solution involves the use of 225-mL polysulfone bottles. To each bottle, 10 grams (dry weight) of ash is added along with 200 mL of leaching solution. Multiple bottles prepared in this manner provide at least 150 mL of leachate and allow for the simultaneous extraction of a large number of samples with minimal space and equipment. It has been found that the standard equipment used for TCLP leaching will generally hold four of the polysulfone containers in the same position usually reserved for one 2-liter container.

9.4 Preparation of Leaching Solution: Leaching solution shall be prepared as recommended by an evaluation of field conditions. Where material disposed in a monofill is above the water table, the leaching solution shall be Type IV water (D1193 Specification for Reagent Water). Where the disposed material will likely be contacted by groundwater,DRAFT

5 either a sample of groundwater from the site or a synthetic groundwater shall be used for leaching. The synthetic groundwater if prepared in the lab shall contain all of the primary mineralization parameters as determined from an analysis of groundwater from the site or from an evaluation of data from analysis reports of water representative of the area of disposal.

9.5 Long-Term Leaching Sampling

B Long-term samples are taken from containers prepared for the shake test in an identical manner to the specimen for the 18-hour sampling period. These containers are sampled at the end of 1 week, 1 month, and 2 months. Longer sampling intervals can be added as required. A convenient method for doing this procedure is to prepare the samples at time intervals so that all of the samples are finished at the same time. For example, one sample is prepared, a second is prepared 1 month later, a third sample 1 month later, and a final sample 18 hours before the other samples are due to be terminated. This saves considerable lab time and expedites the entire procedure.

9.6 Sampling of Leachate

B Leachate is sampled for analysis as specified in D3987 Standard Test Method for Shake Extraction of Solid Waste with Water, Section 9.8.

9.7 Analysis

9.7.1 Selection of Analytes to Be Included in the Report. Analytes include all elements present in the ash in high enough concentrations to be problematic in disposal. These can be determined through screening procedures such as proton-induced x-ray emission (PIXE), instrumental neutron activation analysis (INAA), or plasma emission such as inductively coupled argon plasma (ICAP) spectroscopy or ICAP–mass spectrometry. Analytes for ash screening generally include the eight Resource Conservation and Recovery Act (RCRA) elements for regulatory

purposes.

9.7.2 Determination of Total Concentration of Select Analytes. Analytes selected on the basis of screening (9.6.1) are determined on a bulk sample prepared by digestion of sample in a microwave heated-sealed Teflon bomb. Analyses can be performed according to methods for trace analyses in SW846.

9.7.3 Determination of Analyte Concentrations in Leachates. Concentrations of analytes in leachates shall be determined using methods as described in SW846 or by approved analytical techniques us ing EPA or other approved techniques. All data shall be validated using good laboratory practice and approved quality assurance/quality control (QA/QC) procedures.

10. Calculation

10.1 Calculate the solids content as specified in D3987 Standard Test Method for Shake Extraction of Solid Waste with Water, Section 10.1.DRAFT

6 10.2 Calculation of maximum analyte concentration is determined by dividing the total mass of analyte in a sample by the volume of liquid used for leaching. C = M/V where C = Concentration of analyte M = Mass of sample leached V = Volume of leaching solution used

For this procedure the M:V ratio should be 1:20 as specified in the leaching protocol.

11. Report

11.1 The report shall include the following:

11.1.1 Source of CCSR, date of sampling, a nd preservation method used for leachates. 11.1.2 Description of CCSR including coal source, combustion technique, and method of sample collection (electrostatic precipitator, baghouse, etc.) 11.1.3 Solids content (see Method D2216) 11.1.4 A table of maximum analyte concentrations as determined by the method described in Section 10.2. (bulk chemical analysis) 11.1.5 A table of analyte concentrations as determined from analysis of 18-hour, 1- week, 1-month, 2-month, and any additional extended time intervals selected.

12. Precision and Bias

12.1 No information is presently available on the precision and accuracy or bias of this standard practice. It is recommended that standard QA/QC procedures such as analysis of duplicate samples and spiking of analyte be used for verification.

12.2 The precision of this test will vary depending on the material being leached.

# APPENDIX C

MERCURY INFORMATION CLEARINGHOUSE

REPORTSMERCURY INFORMATION CLEARINGHOUSE

QUARTER 4 – RERELEASE OF MERCURY FROM COAL COMBUSTION

BY-PRODUCTS

ACKNOWLEDGMENT AND DISCLAIMERS

This report was prepared under contract with the Canadian Electricity Association (CEA) and supported by funding from that organization, the Canadian Council of Ministers of the Environment, the U.S. Department of En ergy (DOE) National Energy Technology Laboratory (NETL) Cooperative Agreement No. DE-FC26-98FT40321, and the Center for Air Toxic

Metals ® (CATM ® ) Program at the Energy & Environmental Research Center (EERC). However, any opinions, findings, conclusions, or recommendati ons expressed herein are the author(s) and do not necessarily reflect the views of any of the above-mentioned organizations. The authors also acknowledge preliminary funding from the Utility Solid Waste Activities Group for a similar effort to assemble data on mercury releases from coal combustion by-products.

EERC DISCLAIMER

LEGAL NOTICE This research report was prepared by the EERC, an agency of the University of North Dakota, as an account of work for the CEA and supported by funding from that organization, DOE NETL, and the CATM ® Program at the EERC. Because of the research nature of the work performed, neither the EERC nor any of its employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privat ely owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement or recommendation by the EERC.

U.S. GOVERNMENT DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United

States Government. Neither the United States G overnment, nor any agency thereof, nor any of their employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States G overnment or any agency thereof. The views and opinions of authors expressed herein do not n ecessarily state or reflect those of the United States Government or any agency thereof.REPORT AVAILABILITY

This report is available to the public from the National Technical Information Service, U.S. Department of Commerce, 5285 Port Roya l Road, Springfield, VA 22161; phone orders accepted at (703) 487-4650 and the CEA Mercury Program Web site (www.ceamercuryprogram.ca).i TABLE OF CONTENTS

LIST OF FIGURES ................................................................................................................ ........ ii

LIST OF TABLES................................................................................................................. ......... ii

EXECUTIVE SUMMARY ...........................................................................................................iii

INTRODUCTION ................................................................................................................... ....... 1

MERCURY POLICY ................................................................................................................. .... 2

QUARTER 4 FOCUS: RERELEASE OF MERCURY FROM COAL COMBUSTION

BY-PRODUCTS.................................................................................................................... ......... 4

BACKGR OUND ..................................................................................................................... ....... 5 Mercury and CCBs............................................................................................................... . 5 Anticipated Impacts of Proposed Mercury Control Technologies on CCBs ........................ 7

STABILITY OF ME RCURY ON CCBs........................................................................................ 9 Leaching ....................................................................................................................... ....... 10 Vapor Release .................................................................................................................. ... 14 Microbiological Vapor-Phase Release................................................................................ 16

INTERPRETATION AND CONCLUSIONS.............................................................................. 16

UPCOMING EVENTS................................................................................................................ . 18

CONTACT INFO RMATION....................................................................................................... 19

REFERENCES ..................................................................................................................... ........ 20ii LIST OF FIGURES

1 Categorization of trace elem ents based on volatility. ........................................................... 7

2 Leachate vs. total Hg; nondetects are shown as negative values. ....................................... 13

LIST OF TABLES

1 Leaching Results ............................................................................................................. .... 11

2 Total Hg Concentrations in Fly Ash and Hg Concentrations in SPLP Extracts ................. 12

3 Coal Fly Ash and Leachate (60-day) Mercury Contents .................................................... 12

4 Mercury and Sulfur in Ash.................................................................................................. 14

5 Fly Ash Volatilization Results – Hg Concentration............................................................ 15iii MERCURY INFORMATION CLEARINGHOUSE

QUARTER 4 – RERELEASE OF MERCURY FROM COAL COMBUSTION

BY-PRODUCTS

EXECUTIVE SUMMARY

The topic for this fourth quarterly report is Rerelease of Mercury from Coal Combustion By-Products (CCBs). The stability of mercury associated with CCBs is an issue that has only recently been under investigation, but it has become a more significant issue as the utility industry begins to develop, test and, eventually, install mercury emission controls that may increase the mercury associated with CCBs. The reasons for evaluating the rerelease of mercury

from CCBs are 1) to determine the stability of mercury captured on CCBs and 2) to aid utilities in determining and understanding changes in CCBs associated with mercury control and associated CCB management.

Mercury can be present in quantifiable levels in CCBs, and the mechanisms that allow mercury to be removed with CCBs have become the focus for many developing mercury control technologies. Mercury is most likely to be found in fly ash and flue gas desulfurization (FGD) materials and not in bottom ash and boiler slag because of the relatively high temperatures at which bottom ash and boiler slag are formed and removed from coal combustion systems. As a result of improved mercury removal, especially through particulate control devices and FGD systems, increased mercury concentrations are likely to be observed in respective CCBs.

Potential rerelease mechanisms for mercury from CCBs are identified as 1) direct leachability, 2) vapor-phase release at ambient and elevated temperatures, and 3) biologically induced leachability and vapor-phase release.

Currently, the incorporation of sorbents into the fly ash stream, resulting from injection of sorbent into the flue gas, poses the highest potential impact on CCBs. At this time, the most likely sorbent candidate is activated carbon. The second most likely impact to CCBs from mercury control technologies is in the area of FGD materials, especially in materials generated from wet FGD systems.

Existing data indicate that the mercury content of fly ash and FGD materials collected during tests of mercury control technologies can be significantly increased over the mercury content currently being generated without mercury emission controls in place. Since many mercury control systems currently under development are using carbon sorbents to remove mercury from the flue gas, it is important to note that the unburned carbon associated with some currently generated fly ash has similar sorbent properties as activated carbon used for mercury removal. Both samples of fly ash with unburned carbon and fly ash with activated carbon sorbent have shown good performance in evaluations of mercury stability.

The data assembled and summarized here indicate that mercury associated with CCBs is stable and highly unlikely to be released under most management conditions, including utilization and disposal. Therefore, existing CCB management options are expected to beiv environmentally sound options for CCBs from systems with mercury control technologies

installed.1 MERCURY INFORMATION CLEARINGHOUSE

QUARTER 4 – RERELEASE OF MERCURY FROM COAL COMBUSTION

BY-PRODUCTS

INTRODUCTION

The Canadian Electricity Association (C EA) identified a need and contracted the Energy & Environmental Research Center (EERC) to create and maintain an information clearinghouse on global research and development activities related to mercury emissions from coal-fired electric utilities. With the support of the CEA, the Center for Air Toxic Metals ®

(CATM ® ) Affiliates, the U.S. Department of Energy (DOE), and the Canadian Council of Ministers of the Environment (CCME), the EERC is developing comprehensive quarterly information updates to provide a detailed assessment of developments in mercury monitoring, control, policy, and related research advances.

Ongoing developments in the area of mercury regulations for coal-fired power plants in Canada in the form of Canadawide Standards (CWS) and the United States in the U.S. Environmental Protection Agency’s (EPA’s) Proposed Utility Mercury Reduction Rule illustrate the need for effective mercury control strategies for coal-fired electric utilities. In previous quarterly reports, various mercury control technologies were reviewed in detail. Additionally, a review of the state of technology for mercury measurement was provided in the second quarterly report. As more emphasis is placed on mercury removal from flue gas, increased mercury concentrations may be found in the various coal combustion by-products (CCBs) which are valuable raw materials in the concrete and wallboard industries among others. The fate of these by-products and the mercury contained within them is of significant interest if mercury from coal combustion is going to be eliminated from the global pool. It is of vital importance that mercury removed from coal combustion flue gas and present in CCBs is stable and not hazardous to the environment or human health. If mercury concentrations of these CCBs is significantly increased over that of currently produced CCBs, utilities, CCB users, regulators, and others may need to modify management options to ensure the environmentally sound management of these materials. Therefore, significant research has been conducted to evaluate the mechanisms by which mercury is associated with fly ash and scr ubber effluents. A review of the fate of mercury in coal combustion by-products is provided in this quarterly report.

In order to adequately address the many topics pertinent to mercury research and development and provide the detail necessary for the various stakeholders to make informed decisions, selected topics will be discussed in detail in each quarterly report. Issues related to mercury from coal-fired utilities include the general areas of measurement, control, policy, and transformations. Specific topics that have been addressed in previous quarterly reports include the following:

• Quarterly 1 – Sorbent Control Technologies for Mercury Control

• Quarterly 2 – Mercury Measurement2 • Quarterly 3 – Advanced and Developmental Mercury Control Technologies

As advancements are made in these previously covered topics, updates will be provided as a secondary topic of the quarterly report. However, to date no significant advancements in technology development or measurement control have been identified.

Topics that will be addressed in upcoming quarterly reports include, but are not limited to, the following:

• Mercury policy – updated each quarter based on available information – Upcoming events and news releases – Regulation, policy, compliance strategies, and health developments

• Baseline mercury levels and emissions

• Mercury control – Summary of large-scale test activities and associated economics – Mercury oxidation and control for scrubbed systems – Multipollutant control strategies – Summary of mercury-related economics for commercial systems

• Mercury chemistry and transformations – Mercury chemistry fundamentals, modeling, prediction, and speciation – Mercury fate and transport – impacts on health

MERCURY POLICY

The CCME has been in the process of developing CWS for mercury since 1998 for several significant mercury-emitting sectors and products. Standards have been completed for base metal smelters, incinerators, mercury-containing la mps, and dental amalgam wastes. A CWS for mercury emissions from coal-fired electric power-generating plants is currently under development. Canadian coal-fired generating companies have embarked on a multiyear program to improve the information base around mercury measurement and control that will aid in the development of the CWS. A key component of the CEA Mercury Program is the Coal, Residue, and Flue Gas Sampling and Analysis Program th at companies have undertaken. This program has generated a rich database around mercury emission inventories and management to inform this decision-making process. To date, data have been collected from 16 different power plants operated by ATCO Power, EPCOR, Manitoba Hydro, New Brunswick Power, Nova Scotia Power, Ontario Power Generation, SaskPower, and TransAlta. The preliminary data can be accessed on the program Web site: http://www.ceamercuryprogram.ca. The data is currently undergoing verification and analysis by the CCME and the coal-fired generating companies to ensure the data set is robust for consideration in the 2005 CWS development process. Another componenet of the CEA Mercury Program is the Laboratory Round Robin, a review of analytical laboratories. Develope d by CEA member companies and funded by CCME,3 this program consisted of a two-phased analysis and quality assurance program. Mercury concentrations in fuel, by-products, and stack gas samples tend to exist at very low levels; therefore, accurate laboratory analysis is critical to ensuring an effective mercury inventory program. Phase I of this program has been completed and focused on assessing participating laboratories by analyzing standard samples over a 6-month period. Phase II of the Laboratory Round Robin provided ongoing quality assurance for the data collection program and benchmarked several common Canadian coals for mercury and other coal-specific properties. Laboratories participating in the program tended to do very well. For more information regarding the Laboratory Round Robin, go to http://www.ceamercuryprogram.ca.

In the United States, EPA has received 586,000 comments on the Proposed Utility Mercury Reduction Rule after it extended the comment period to June 29, 2004. From this record number of comments, including 4800 unique comments, approximately 200 comments contained substantial content and ranged in length from five to ten pages.

In his address to the 2004 annual Air and Waste Management Mega Symposium, EPA Administrator Mike Leavitt stated that EPA is in the process of reviewing the comments which will be summarized in a comment response document in advance of the March 15 deadline for the final rule. Additionally, he laid out five guidi ng principles that EPA is using in devising the final mercury rule. The rule will:

1) Concentrate on the protection of children and pregnant women.

2) Stimulate and encourage early implementation of new technology.

3) Leverage the $50 billion investment of the Clean Air Interstate Rule to reduce total mercury emissions.

4) Take into account the need to maintain America’s competitiveness worldwide.

5) Be one component of many efforts to reduce mercury emissions.

Once the EPA comment response document becomes available, a summary will be provided in the following quarterly report.

In Europe, the European Commission recently issued a consultation document on mercury which evaluated mercury emissions, production, trade, and use and reviewed the health and environmental impacts of mercury. The original focus of the effort was Europe’s chlor-alkali industry, which is the largest user of mercury in Europe; however, it is in the process of phasing out its use. A copy of the Commission’s document is available at the following Web site: http://europa.eu.int/comm/environment/chemicals/mercury/pdf/consultation.pdf.4 Currently, coal combustion in power plants is the largest single source of mercury emissions in Europe. However, the issue of mercury emissions is complicated by two opposing trends. In response to concerns over mercury, emission standards are tightening. However, unlike many other parts of the world, mercury emissions and environmental concentrations in Europe appear to be falling according to data collected between 1990 and 2000 and summarized at the aforementioned Web site. Based on this data, it is unclear what strategy the Commission will take regarding mercury emissions, and unlike the United States, it is not certain that Europe will introduce mercury controls at an early stage.5 QUARTER 4 FOCUS: RERELEASE OF MERCURY FROM COAL COMBUSTION

BY-PRODUCTS

Mercury and other air toxic elements can be present in fly ash, flue gas desulfurization (FGD) material and, to a lesser extent, bottom ash and boiler slag. The mercury that can associate with CCBs is a function of the mercury content of the coal used, the coal properties, the combustion technology, and the emission control technologies at the plant. Generally speaking, mercury released from the combustion of coal remains in the gaseous state until cooling to temperatures typical of back-end emi ssion control equipment, at which point it either reacts with components of the flue gas and is removed from the system as particulate-bound mercury in the ash, a sulfur compound with FGD control, or is emitted out the stack.

Mercury emission control technologies are be ing developed to remove mercury from the flue gases and, in many cases, these technologies are designed to incorporate the mercury removed from the flue gas into the fly ash or FGD material. The stability of mercury associated with CCBs is an issue that has only recently come under investigation, but it has become a prominent question as the industry strives to develop and test mercury emission controls that may consequently increase the mercury associated with CCBs. The primary reason for evaluating the rerelease of mercury from CCBs is to aid utilities in determining and understanding changes in CCBs associated with mercury control and how these changes may impact CCB management.

The rerelease mechanisms for mercury from CCBs are 1) direct leachability and 2) vaporphase release at ambient and elevated temperatures. Both leachability and vapor-phase transport can be impacted by microbiological action on the CCBs.

BACKGROUND

Mercury and CCBs

Mercury can be present in quantifiable levels in CCBs. It is most likely to be found in fly ash and FGD materials and not in bottom ash and boiler slag because of the relatively high temperatures at which bottom ash and boiler slag are formed and removed from coal combustion

systems.

Historically, data on mercury concentrati ons in fly ashes have varied widely, but leachability of mercury has generally fallen below detection limits (1–4). Hassett et al. (5–7) reported mercury concentrations ranging from <0.01 to 2.41 ppm in samples of fly ash from all

ranks of coal from both the eastern and wester n United States. Consistent with what is known about the chemistry of mercury in combustion systems, the average mercury content of fly ash is higher than that for bottom ash or slag and increases with the carbon content of the ash (8, 9). The mercury contents of FGD scrubber materials ar e, in turn, higher on average than those of fly ash (10). Concentrations of 39 and 70 ppm we re reported by DeVito and Rosenhoover (11) and DeVito (12) for two FGD materials.6 Nearly 100% of the mercury present in coal exits the boiler with the flue gas. The speciation of that mercury however is highly infl uenced by the composition of the flue gas (12). Data from the EPA Information Collection Request (ICR) allowed for some generalizations to be made regarding the potential for various CCBs to capture mercury. Hot-side electrostatic precipitators (ESPs) do not allow capture of mercury on the fly ash because the temperature is too high, but cold-side ESPs and fabric filters operate at temperatures that do allow some mercury to be removed from the flue gas. Fabric filters tend to remove significant percentages of both elemental and oxidized mercury because of the excellent gas–solids contact as the flue gas moves through the dust cake on the filter. Wet FGD (WFGD) systems and spray dryer absorbers have been shown to be effective in removing oxidized mercury from flue gas. Additional information on the results collected in the EPA ICR can be found in other sources (13–16). CEA has a program in place with eight coal-fired power generation companies in Canada designed to develop information associated with mercury em issions from coal-fired generation and to find cost-effective and efficient management options for mercury emissions (more information is available at the following Web site: http://www.ceamercuryprogram.ca/EN/ program_overview.html). The CEA program collected information on the mercury content of CCBs, and the data assembled are under review.

The EPA ICR data did not include information on the concentrations of mercury on the CCBs generated at the test facilities, so it is an inference that the noted mercury reductions indicate an associated mercury capture on the CCBs. It is logical to conclude that at least some mercury can be captured by fly ash and/or FGD material. It is known that the mercury can be present in the flue gas as either elemental and/or oxidized species and that both elemental and oxidized mercury can be sorbed on carbon. Mercury can be physically or chemically sorbed on carbon, so it can be assumed that unburned carbon present in fly ash can sorb mercury by either or both of these mechanisms. While elemental mercury can be sorbed on carbon, it is actually transformed to oxidized mercury (17), implying that its stability on the carbon will be similar to that of oxidized mercury. The mechanism of mercury capture on unburned carbon is expected to be equivalent to that of activated carbon introduced into the flue gas as a means of mercury removal and control. However, insufficient data exist to extrapolate that assumption to include modified activated carbons such as halogenated or sulfuric-impregnated carbon or other modified carbon sorbents under development. In many cases, the quantities of carbon sorbent needed for mercury control are not expected to be higher than the level of unburned carbon already found in some fly ashes. The activation of the carbon sorbent, however, is anticipated to be problematic for use of these fly ashes as a mineral admixture in concrete because the activated carbon has been shown to sorb standard air-entraining admixtures and limit the function of the admixture to produce an air-entrained concrete, which is needed for numerous applications.

The EPA ICR data strongly imply that certain co al fly ashes may exercise a catalytic effecton the oxidation of elemental mercury. Inorganic compounds such as manganese oxide, ironcontaining compounds, and chromium and nickel oxides have been shown to catalyze mercury oxidation (18, 19), but various tests with the addition of some of these compounds to simulated flue gas did not produce the anticipated oxidation of mercury (20, 21). The mechanism of sorption of mercury on fly ash is extremely complicated and has not yet been fully investigated.7 Anticipated Impacts of Proposed Mercury Control Technologies on CCBs

Proposed mercury emission controls have the potential to impact fly ash and FGD materials because mercury is highly volatile and should leave the combustion zone in the flue gas. As noted in Figure 1, mercury should be volatilized and emitted fully in the vapor phase in combustion systems. Mercury in the vapor phase in the flue gas has the potential to be sorbed onto the fly ash, carbon (either unburned carbon or sorbent), other sorbents, and the FGD reagent, or it may be emitted. The highest potential for mercury controls to impact CCBs is through the use of sorbent injection technologies th at will incorporate the sorbent into the fly ash stream. The most likely sorbent candidate is activated carbon, even though other sorbents have been and are being tested. Testing at four full-scale boilers that measured mercury across particulate control devices gives some insight to the importance of particulate control in mercury removal and indicates that increased carbon relates to increased mercury removal. Even though no sorbent injection or other add-on mercury control technology was in place during these tests, the unburned carbon present in the fly ash provided significant mercury removals. Mercury removals ranged from a low of 28% for an ESP to between 61% and 99% for units equipped with reverse-gas baghouses (22). The highest mercury removals were observed where there was a high level of unburned carbon in the fly ash (high loss on ignition [LOI]). Pilot tests reinjecting power plant fly ashes ahead of a reverse-gas baghouse indicated removals between 13% and 80% at temperatures in the range of l35°–l 60°C (275°–320°F), and again, removals increased with increased LOI. It must be noted that LOI is not equivalent to carbon content of ash.

Energy &

Environmental

Research

Center 

### Categorization of Trace Metals Based on Volatility

Class III

Volatilized and emitted fully

in the vapor phase – Not

enriched in the fly ash

Class II

Enriched in the fly ash and depleted in the bottom ash

Class I

Equally distributed between bottom ash and fly ash Hg

Br Cl F

B Se IIncreasing Volatility

Eu Hf La Mn Rb Sc Sm Th Zr As Cd Ga Ge Pb Sb Sn Te Ti Zn

Ba Be Bi Co Cr Cs Cu Mo Ni Sr Ta TI U V W

Figure 1. Categorization of trace elements based on volatility.8 At tests performed at Wisconsin Electric’s Pleasant Prairie Power Plant, Unit 2, in 2001 (23), activated carbon injection (ACI) resulted in mercury removals of 40%–70%, with increased removals correlating to increased carbon injection. The LOI of the fly ash produced without sorbent injection at Pleasant Prairie was approximately 0.5% but was increased to as high as 3.5%. More noteworthy than the LOI increase was the impact of that increase on the performance of the fly ash–sorbent mixture in th e Foam Index Test, which provides an indication of the appropriateness of the fly ash to be used with an air-entraining agent (AEA). The fly ash– sorbent mixture not only failed the Foam Index Test, but the fly ash from Unit 2 continued to fail

the test for 5 weeks after the conclusion of the sorbent injection tests. The presence of carbon in fly ash has been reported to impact the use of fly ash in concrete. The impact relates to air entrainment in concrete. AEAs are used to facilitate the incorporation of very small air bubbles into the concrete mix. The presence of these air voids provides improved freeze-thaw durability of the concrete. For commonly used AEAs, the pr esence of carbon interferes with the formation of the air voids by sorbing the AEA. Early in the development of specifications for fly ash for use as a mineral admixture in concrete, an upper limit of 6.0% LOI was set for fly ash in order to

address this technical issue associated with unburned carbon in fly ash. The potential addition of activated carbon is expected to exacerbate the problem associated with carbon in fly ash and its use in concrete. Preliminary results, such as those from the Pleasant Prairie tests, indicate that the long-standing limit of 6.0% LOI will not be adequate to determine the appropriateness of fly ash activated carbon mixtures for use in concrete. Work addressing this issue is under way by various academic and industrial groups and includes development of AEAs which will perform adequately even with higher carbon content fly ash, admixtures that deactivate the carbon and allow successful use of standard AEA, and carbon removal systems. High carbon fly ash is also used as a feedstock component for cement clinker production which is a high-temperature process. The chemistry of mercury suggests that mercury associated with fly ash (or the carbon in fly ash) will be released as vapor. Since there is evidence that noncarbon sorbents sorb mercury, research needs to be undertaken to determine the fate of mercury in a cement kiln and the associated emission control systems.

Senior et al. (23) also reported on activat ed carbon sorbent injection tests at Alabama Power’s Gaston Station, which has a hot-side E SP and a COHPAC (compact hybrid particulate collector), which provides a second particulate collection after the ESP for polishing purposes. This system allows the injection of sorbent afte r the bulk of the fly ash has been collected and separate collection of any remaining fly ash in the flue gas stream along with the mercury-loaded

sorbent.

Noncarbon sorbents have been tested for their mercury removal potential, with the intent of identifying sorbents that would capture and hold mercury and have a reduced impact on the fly ash for potential utilization especially in concrete (24, 25). One fly ash from a western subbituminous coal was shown to have a significant mercury sorption capacity after heating to remove all carbon (22), and mercury capture was improved by spray cooling to reduce the gas temperature to 110°C (230°F).

Another potential impact to CCBs from mercury control technologies is in the area of

calcium-based FGD materials. It has been show n in field tests (26–28) that WFGD is successful9 at removing a high percentage of oxidized mercur y from the flue gas stream. Elemental mercury is not removed by WFGD, but existing WFGD systems capture approximately 90% of the mercury (II) at essentially no cost to the utility. Studies to enhance the capture of mercury in WFGD systems, generally by enhancing the oxidized mercury in the flue gas, are under way (29–38). Studies are also being performed on removing elemental mercury in WFGD systems as well as on increasing the percentage of oxidized mercury that is removed. The use of WFGD systems for mercury control has the potential to facilitate multipollutant control and may provide some impetus for utilities to consider WFGD systems over other SO 2 controls for DOE Phase II (39) and new fine-particulate control standards. It has been shown that FGD material generated from wet systems can be oxidized to produce gypsum and that mercury present in the WFGD material is partitioned into the gypsum, implying that the mercury is not readily leached from the gypsum (40). The primary effort in the area of mercury emission control using FGD systems has been performed using wet systems, although other types of calcium-based FGD systems also are expected to remove oxidized mercury from flue gas at varying efficiency levels.

STABILITY OF MERCURY ON CCBs

As previously noted, data on mercury concen trations in fly ashes are varied. CEA data (http://www.ceamercuryprogram.ca/EN/program_overview.html) indicates mercury concentrations ranging from <0.002 to 1.221 ppm in fly ash and from 0.001 to 0.342 ppm in bottom ash. Hassett et al. (5–7) reported mercury concentrations ranging from <0.01 to 2.41 ppm in samples of fly ash from full-scale coal-fired power plants from all ranks of U.S. coal. Concentrations of 39 and 70 ppm were reported by DeVito and Rosenhoover (11) and DeVito (12) for two FGD materials. The mercury content of FGD material is higher on average than the mercury content of fly ash which is consistently higher than the concentrations found in bottom ash or boiler slag (10). The mercury concentration of fly ash tends to increase with the carbon content of the ash (8–9). Recently, the EERC reported that the mercury content of fly ash and FGD collected during tests of mercury control t echnologies can be significantly increased with samples containing a total mercury concentration as high as 120 ppm reported. However, of 21 samples collected from mercury control demonstrations, only 6 had mercury concentrations greater than those noted for samples from systems without mercury control. Those six samples had mercury concentrations ranging from 4.7 to 120 ppm.

Limited data on fly ash–carbon sorbent mixtures (eight total samples) indicate a range of 0.2–5.5 ppm total mercury content, with only two samples from one location providing data indicating mercury content greater than 1 ppm mercury. The limited data do not provide adequate evidence that mercury contents of fly ash–carbon sorbent mixtures will be consistently higher than fly ash produced without mercury em ission controls installed. Senior and Bustard (23) reported mercury concentrations in the range of 10–100 ppm in spent sorbent from test runs using the COHPAC system. These data points should be considered separately from samples of fly ash or FGD material that may be impacted by mercury emission controls.

The total concentration of mercury on CCBs or sorbents cannot be used as an indicator of stability. The stability of mercury on CCBs or sorbents can only be evaluated by subjecting the10 sample to a variety of laboratory tests that expose the material to conditions that simulate those in field settings for realistic management options for the material in question.

Leaching 1

Various leaching methods are available to evaluate CCBs and other materials for environmental performance, but current data on the leachability of mercury from CCBs has been generated primarily by use of the TCLP (toxicity characteristic leaching procedure) and the SGLP–LTL (synthetic groundwater leaching pr ocedure–long-term leaching). The TCLP, frequently applied to CCBs, involves the extraction of contaminants from a 100-g size-reduced sample of waste material with an appropriate extraction fluid. A 20:1 liquid-to-solid (L/S) ratio (mass/mass, m/m) is employed, and the mixture is rotated for 18 ± 2 hr at 30 rpm using a rotary agitation apparatus. The extraction fluid used for the extraction depends on the alkalinity of the waste material. Very alkaline waste materials are leached with a fixed amount of acetic acid without buffering the system (pH 2.88 ± 0.05), while other waste materials are leached with acetic acid buffered at pH 4.93 ± 0.05 with 1-N sodium hydroxide. After rotation, the final pH is measured, and the mixture is filtered using a glass fiber filter. The filtrate is collected in an appropriate container, and preservative may be added if needed. The filtrate is analyzed for a number of constituents. EPA now recognizes that the TCLP is an inappropriate test for use with CCBs. The SGLP–LTL is a procedure developed at the EERC. The SGLP–LTL was designed to use a synthetic groundwater for the leachate to more closely simulate environmental conditions and to include longer-term leaching time frames for reactive CCBs. In many cases, the SGLP– LTL uses distilled, deionized water because specific site information for the management options to be applied to the CCB is unavailable. The complete SGLP–LTL usually includes leaching times of 18 hours, 30 days, and 60 days. However, LTL is only necessary for alkaline samples (pH >10), because CCB samples with pH values below 10 do not undergo long-term hydration reactions that impact leachate characteristics.

The amount of mercury leached from currently produced CCBs is extremely low and generally does not represent an environmental or rerelease hazard. Concentrations of mercury in leachates from fly ashes and FGD material usi ng either the TCLP or the SGLP are generally below detection limits (0.005 to 0.05 μg/L) (5, 11, 12, 24, 30, 31, 33).

Mercury leachate concentrations from vari ous types of leaching tests (both batch and column) for CCBs resulting from the use of mercury control technologies have been reported. In addition to TCLP and SGLP, the synthetic precip itation leaching procedure (SPLP) and synthetic acid leaching (SAL) batch tests have been used as short-term methods. LTL, a component of the SGLP, has also been performed using 30- and 60-day equilibration periods.

1 The authors of the various references have reported data in several different formats. The following concentrations are equivalent: ppm (parts per million) = μg/g; ppb (parts per billion) = μg/kg, ng/g, μg/L; and ppt (parts per trillion) = pg/g, ng/L. The EERC has used ppm, ppb, and ppt to express concentrations associated with solid materials and vapor-phase releases. μg/L and ng/L have been used for concentrations in liquids such as leachate

concentrations.11 Senior et al. (23, 41) reported that little or no detectable Hg was leached by TCLP or SGLP from fly ash samples resulting from powdered activated carbon (PAC) injection demonstrations at four coal-fired power plants . As shown in Table 1, baseline fly ash, fly ash + sorbent, and COHPAC samples all gave similar leaching results, illustrating very low

concentrations.

Table 1. Leaching Results (leached by the EERC) (23, 41) Hg in, μg/L

Plant Location Injection Rate,

lb/MMacf TCLP SGLP Salem Harbor ESP Row A (control) 0 0.034 <0.01

Salem Harbor ESP Row A 10 <0.01 <0.01

Salem Harbor ESP Row A 10 <0.01 <0.01 Brayton Point New ESP 0 <0.01 0.01 Brayton Point Old ESP 1 0 0.02 0.05 Brayton Point New ESP 10 0.07 0.03 Brayton Point Old ESP 1 10 0.03 0.01 Brayton Point New ESP 1 20 <0.01 0.01 Brayton Point Old ESP 20 0.02 0.02

Gaston COHPAC B-side 1.5 0.01 <0.01

Gaston COHPAC B-side 1.5 NA 2 <0.01

Gaston COHPAC B-side 1.5 <0.01 <0.01 Pleasant Prairie ESP hopper composite 10 <0.01 <0.01 Pleasant Prairie ESP hopper composite 10 <0.01 <0.01 Pleasant Prairie ESP hopper composite 10 <0.01 NA

1 Sorbent injected downstream of the old ESP.

2 Not applicable.

Gustin et al. (42, 43) and Ladwig (44) also reported on the leachability of Hg from the Pleasant Prairie and Brayton Point PAC injection tests using SPLP (see Table 2). An increase in the Hg leachate concentration was noted between the baseline and PAC injection samples by Gustin et al. for the Pleasant Prairie samples, which were all collected from the same ESP. The Brayton Point baseline and test samples were collect ed at different points, so a direct comparison

cannot be made.

Fly ash samples from pilot-scale test burns using ACI and the Advanced HybridTM filter were leached using SGLP and LTL (45). The SG LP and 30-day LTL leachate results were below the limit of quantification (i.e., <0.01 ppb); however, the 60-day LTL leachates indicated a small release of mercury (Table 3). Pavlish et al. (45) reported that the results indicate that the fabric

filter and Advanced HybridTM filter were more effective in capturing particulate Hg relative to

the ESP.12 Table 2. Total Hg Concentrations in Fly Ash and Hg Concentrations in SPLP Extracts (adopted from Gustin et al. [43]) Sample Total Hg, ppb Leached Hg, ng/L S2A-1 (base) 247 0.65

S2A-1 a 0.8

S2A-1 a 0.6

S2A-1 a 0.2 S2A-2 (ACI) 2300 ND b

S2A-2 a ND

S2A-2 a 2.9 S2A-3 (ACI) 1040 3

S2A-3 a 6.9

S2A-3 a 10.7 B7A-1 (base) 670 2.6

B7A-1 a 2.6 B7A-2 (ACI) 752 ND

B7A-2 a ND B7A-3 (ACI) 670 ND

a Replicated measurements.

b Not detected.

Table 3. Coal Fly Ash and Leachate (60-day) Mercury Contents (adapted from Pavlish et al. [45])
Fly Ash (leachate) Mercury, ppm (ppb)

Coal Activated Carbon Injection Rate, g/hr ESP FF Advanced HybridTM Filter Poplar River NA a NA 0.030 (<0.01) NA NA Poplar River Luscar char 40–150 0.218 (0.032) NA NA Poplar River Luscar char 10–50 0.011 (<0.01) 8.66 (<0.01) NA Poplar River Luscar char 20–120 NA NA 1.15 (<0.01) Freedom Fine Luscar char 15–115 0.198 (<0.01) NA NA Freedom DARCO FGD 10–40 Not analyzed 17.8 (0.057) NA Freedom Luscar char 10–40 0.040 (<0.01) 5.73 (<0.01) NA Freedom Luscar char 10–40 NA NA 0.865 (<0.01)

a Not applicable.

In early work at the EERC, 22 samples from full-scale power plants operating without any mercury controls were subjected to SGLP, and all resulting leachate mercury concentrations were <0.01 μg/L, with one exception where the leachate concentration was 0.018 μg/L (46). More recently, the EERC reported that SGLP leachate concentrations of mercury ranged from <0.01 to 0.05 μg/L and TCLP leachate concentrations of mercury ranged from <0.01 to 0.14 μg/L (47). These data, which included evaluati ons of fly ash from systems with and without mercury controls in place, are shown in Figur e 2. EERC researchers concluded from the data presented that there was no correlation between total mercury content and leachable mercury.13 Results of column leaching performed by Kaz onich et al. (48) indicated that mercury leached at extremely low levels when subjected to leaching by solutions ranging from acidic to alkaline. Results of continuing work at DOE ’s National Energy Technology Laboratory (NETL) using the column leaching procedure and multiple leaching solutions indicated that release of mercury from CCBs by leaching was not related to the total concentration of mercury in the sample (49). The NETL data also indicated that higher leachate concentrations were observed with the acetic acid leachate; however, NETL concluded that it was unlikely that leachate concentrations of mercury would exceed drinking water standards.

The use of sodium tetrasulfide (Na 2 S 4 ) injection as a mercury control technology is being explored in pilot-scale facilities at Southern Research Institute (50). A bituminous and a

subbituminous coal were tested and associated ash samples subsequently leached using TCLP. Leachate concentrations of mercury are shown in Ta ble 4. An increase in tota l Hg content in the ash

was noted for both coals with Na 2 S 4 injection; however, on comparison to leachates from baseline ash, an increased mercury leachate concentration was only noted for the bituminous ash while the subbituminous ash had a lower mercury leachate concentration.

The effect of flue gas desulfurization used for Hg control has been reported by Richardson (51) and Golden (52). Associated TCLP l eaching results for forced oxidation limestone processes were all <0.06 μg/L, while the single FGD material from a system using inhibited oxidation gave a mercury leachate concentration of 0.34 μg/L. Withum et al. (53, 54) leached a variety of Hg control technology CCBs with both TCLP and American Society for Testing and Materials (ASTM) D3987 tests. All samples had Hg leachate concentrations of <1.0 μg/L.

Figure 2. Leachate vs. total Hg; nondetects are shown as negative values.14 Table 4. Mercury and Sulfur in Ash (50)

Run

No. Coal Type Injection Condition Na 2 S 4 in Flue Gas, ppmv Total Hg in Ash, ppb TCLP Hg, μg/L

6 Bit. a Baseline condition 0 1.28 20.6

7 Bit. 13.5 1.94 76.8 8 Bit. Raised flue gas temperature 13.5 1.94 76.8 9 Bit. Lowered flue gas temperature 13.5 1.94 76.8 10 Bit. Normal temperature 6.8 NA b NA 11 Bit. Repeat condition 2 13.5 NA NA 12 Bit. Inject chlorine through burner 13.5 NA NA 13 Bit. Half chlorine injection 13.5 2.20 69.9 14 Bit. Maintain chlorine injection, turn

off Na 2 S 4 injection 0 1.84 ± 0.28 70.4

15 PRB Baseline 0 1.76 65.7

16 PRB 12.2 1.93 0.342

17 PRB 6.1 1.93 0.342

18 PRB Return to baseline 0 1.93 0.342

19 PRB Residual effect 2.9 1.93 0.342

20 PRB Start fresh 2.9 NA NA

21 PRB 6.1 NA NA 22 PRB Increased air injection temperature 6.1 1.29 30.5

a Bituminous coal.

b Not applicable.

Leaching tests on four carbon sorbents were performed using TCLP. Detectable levels of mercury in the leachate were observed for only one sorbent (55). These preliminary results suggest that mercury is not readily leached from sorbents, which implies that the rerelease of mercury from spent sorbents such as those reported by Senior and Bustard (23) may not pose a significant management issue relative to leaching.

Vapor Release 2

The release of mercury vapor from CCBs resu lting from the use of Hg control technologies has been evaluated on a limited basis. Methods of determining the release include measuring the Hg in the air, capturing the Hg released over extended time periods, and evaluating the Hg content of the CCBs at varying time periods, which generally require very sensitive analytical techniques. Hassett and Heebink performed long-term ambient-temperature desorption experiments, and results indicated that five of the six CCBs analyzed acted as mercury sinks (56).

Butz and Smith (57) compared the total Hg content of CCBs initially and after 8 months in open and closed containers to determine offgassing. The results reported suggest that the Hg bound to the ash and/or activated carbon is fairly stable.

2 The authors of the various references have reported da ta in several formats. The following concentrations are equivalent: ppm (parts per million) = μg/g; ppb (parts pe r billion) = μg/kg, ng/g, μg/L; and ppt (parts per trillion) = pg/g, ng/L.15 Fly ash volatilization studies performed by Schwalb et al. (54) compared total mercury contents of several ash samples as-received and after exposure to elevated temperatures (100° and 140°F [37.7° and 60°C]) for 6 months with total mercury concentration measured at 3 and 6

months. Results are shown in Table 5.

Table 5. Fly Ash Volatilization Results – Hg Concentration, ppm (54)

3 month 6 month

Plant ID As-Received 100°F 140°F 100°F 140°F

3 0.09 ± 0.02 0.09 0.10 0.12 0.17

6 0.29 ± 0.05 0.34 0.32 0.38 0.34

6 0.19 ± 0.04 0.22 0.25 0.28 0.24

6 0.69 ± 0.11 0.72 0.69 0.69 0.69

4 0.08 ± 0.02 0.11 0.12 0.13 0.12

4 0.08 ± 0.02 0.09 0.10 0.11 0.13

Gustin et al. (42, 43) and Ladwig (44) ev aluated the Hg flux for CCBs. Results indicated that both baseline fly ash samples and those with activated carbon exhibited a net deposition of Hg on the fly ash. Deposition was greatest on the samples with activated carbon, leading Gustin et al. (42) to conclude that it was possible that the higher carbon in the ash facilitated atmospheric Hg uptake.

Gustin et al. (43) also evaluated Hg flux fr om fresh samples and samples exposed to air for 9 months in order to determine the potential for reemission of deposited atmospheric Hg from ash. Experiments included the addition of water to the samples exposed to air which resulted in a difference in the Hg flux noted. Mercury deposite d on dry ash, as previously noted, but results indicated that mercury was emitted from the wet ash. Gustin et al. (43) reported that the emission rate for the wet ash declined over time and returned to deposition. The addition of water to the fresh samples resulted in less of a difference in flux, indicating that Hg released after the addition of water was deposited atmospheric Hg and that the fresh ash did not have loosely bound, readily released Hg.

Limited information has been reported on the stability of mercury captured on sorbents (55). Results of thermal desorption tests indicate that mercury is thermally released from sorbents at temperatures considerably below the peak temperatures observed for fly ashes. Significant percentages of the mercury captured on the saturated sorbents were released upon heating above 135°C (275°F) in nitrogen, carbon dioxide, or flue gas; and 30%–50% of the original mercury capture capacity of the sorbent was regenerated after one or two regeneration cycles. Ambient release of mercury into a low flow rate of air was determined by collecting desorbed mercury on a sorbent. After correcting for blank determinations, essentially no mercury was released at ambient temperature (24°C [75°F]) from either of the sorbents tested. These data may be valuable in assessing the potential for rerelease of mercury from spent sorbents.16 Microbiological Vapor-Phase Release

EERC researchers have reported on the microbiologically induced release of mercury vapor from CCBs (58) under aerobic and anaerobic conditions. Results of these preliminary experiments indicated that both elemental and or ganomercury were released. The experimental matrix consisted of eight flasks under aerobic conditions (using breathing-quality air) and eight flasks under anaerobic conditions (using argon). In each set of eight flasks, two contained only buffer, three contained a slurry of the CCB with buffer, and three contained a slurry of the CCB with buffer and glucose. An 80-g aliquot of CCB was placed in the flasks, and 100 mL of aphosphate buffer (with or without glucose) was added to create a neutral pH. The CCBcontaining flasks also had 100 μL of mixed bact erial culture added. Vapor traps collected the organo- and elemental mercury released from the system, and leachates were collected at the conclusion of the 30-day experiment.

At the 2004 Combined Power Plant Air Pollutant Control Mega Symposium, the EERC reported that oganomercury species were detected at very low levels both in the vapor and leachate generated from the microbiologically mediated release experiments (58). The EERC reported speciation of these organomercury compounds in leachates to be dimethyl and diethyl mercury but present at levels <5 ng/L (ppt).

INTERPRETATION AND CONCLUSIONS

The data currently available on CCB mercury content and stability are limited because demonstration of mercury control technologies has only recently been initiated. Data on fly ash and FGD materials that have been generated at full-scale coal-fired power plants without mercury emission controls in place indicate that the concentration of mercury is relatively low for most samples, with total mercury concentrations ranging from <0.01 to 2.41 ppm. It has also been reported that the mercury content of fly ash and FGD collected during tests of mercury control technologies can be significantly increased with samples with a total mercury concentration as high as 120 ppm reported; however, of 21 samples collected from mercury control demonstrations, only six had mercury concentrations greater than those noted for samples from systems without mercury control. These data represent a very limited number of samples, types of mercury control, and combustion systems, but in 2004–2006, several tests of mercury emission control technologies at full-scale facilities will be performed, and a concerted effort is planned by DOE to fully evaluate the stability of mercury associated with the CCBs produced from these tests.

Carbon sorbents are expected to be used in many systems as part of the mercury control technologies, so it is important to note that normal activated carbon sorbents are not expected to perform differently than unburned carbon associated with fly ash, and samples of fly ash with unburned carbon have shown similar performance in evaluations of mercury stability. The stability of the mercury associated with these materials is similar to that of materials generated without mercury emission controls. Work on re lease of Hg from modified activated carbon sorbents is ongoing, and results are not available to assess the Hg behavior associated with these

sorbents.17 Existing data indicate that the stability of mercury on fly ash and FGD material is similar for samples collected at sites without mercury controls and during tests of mercury control technologies. Data assembled and summarized in this document indicate that mercury associated with CCBs is environmentally stable under most management conditions, including utilization and disposal. The exception to this is exposure to high temperatures such as those that may be achieved in cement production.

Evaluations of CCBs that are collected from full-scale demonstration of mercury control are needed to confirm the data available in the literature. The data do not sufficiently represent all of the variables that may be associated with CCBs generated when mercury controls are in place. Existing data indicate that present CCB management options are expected to be environmentally sound for CCBs from systems with mercury control technologies installed, but information that should become available in the next few years is expected to allow conclusions to be drawn from a broader and more representative sample set.18 UPCOMING EVENTS

By-Product Beneficial Use Summit November 8, 2004, Kansas City, Missouri http://www.byproductsummit.com/papers.html

Coal Combustion Products Partnership Workshop November 16, 2004, Atlanta, Georgia, contact William Aljoe (412) 386-6569 http://fossil.energy.gov/news/events/

POWER-GEN International November 30–December 2, 2004, Orlando, Florida http://pgi04.events.pennnet.com

229th ACS National Meeting March 13–17, 2005, San Diego, California http://oasys.acs.org/acs/229nm/topics.html

World of Coal Ash April 11–15, 2005, Lexington, Kentucky http://www.acaa-usa.org/ASP/EventCalendar.ASP?YEAR=2005

30th International Conference on Coal Utilization & Fuel Systems (formerly Clearwater Coal Conference) April 17–21, 2005, Clearwater, Florida http://www.coaltechnologies.com

International Conference on Clean Coal Technologies for Our Future May 10–12 2005, Sardinia, Italy, contact Rodney Anderson (304) 285-4709 http://fossil.energy.gov/news/events/

A&WMA 98th Annual Conference and Exhibition June 21–24, 2005, Minneapolis, Minnesota http://www.awma.org

230th ACS National Meeting August 28–September 1, 2005, Washington, D.C. http://oasys.acs.org/acs/230nm/topics.html

Air Quality V: Mercury, Trace Elements, and Particulate Matter Conference September 18–21, 2005, Washington, D.C. http://www.undeerc.org19 CONTACT INFORMATION

For more information, please contact:

Michael Holmes

Senior Research Advisor Energy & Environmental Research Center

PO Box 9018 Grand Forks, ND 58202-9018 mholmes@undeerc.org (701) 777-5276

John Pavlish

Senior Research Advisor Energy & Environmental Research Center

PO Box 9018 Grand Forks, ND 58202-9018 jpavlish@undeerc.org (701) 777-526820 REFERENCES

1. Carlson, C.; Adriano, D.C. Environmental Impacts of Coal Combustion Residues. J. Environ. Qual. 1993

, 22 , 224–247.

2. EPRI. Inorganic and Organic Constituents in Fossil Fuel Combustion Residue, Vol. 1: A
Critical Review; EPRI Report EA-5176, Project 2485, Aug 1987.

3. Hassett, D.J. Evaluation of Leaching Potential of Solid Coal Combustion Wastes ; Final Report for Indiana Coal Council; Energy & Environmental Research Center: Grand Forks,
ND, Dec 1991.

4. Pflughoeft-Hassett, D.F.; Dockter, B.A.; Eylands, K.E.; Hassett, D.J. Survey and Demonstration of Utilization Potential of North Dakota Lignite Ash Resources ; Final Report for the Industrial Commission of North Dakota; 96-EERC-04-01; Energy & Environmental Research Center: Grand Forks, ND, April 1996.

5. Hassett, D.J.; Pflughoeft-Hassett, D.F.; Laudal, D.L.; Pavlish, J.H. Mercury Release from Coal Combustion By-Products to the Environment. In Proceedings of the Specialty Conference on Mercury in the Environment: Minneapolis, MN, Sept. 15–17, 1999; Air and Waste Management Association: Pittsburgh, PA, 1999; pp 485–493.

6. Hassett, D.J.; Heebink, L.V.; Pflughoeft-Hassett, D.F. Potential for Mercury Release from Coal Combustion By-Products. In Proceedings of the Air Quality III: Mercury, Trace Elements, and Particulate Matter Conference ; Arlington, VA, Sept 9–12, 2002; Paper A2-

02.

7. Pflughoeft-Hassett, D.F. Overview of EERC Studies in Evaluating CCR Products and Identification of Major Data Gaps. Agenda for Coal Combustion Residues Workshop; Research Triangle Park, New Jersey, January 10–11, 2001.

8. Zhenglong, L.; Hwang, J.Y. Mercury Distribution in Fly Ash Components. In Proceedings of the Air and Waste Management Association 90th Annual Meeting and Exhibition ; Toronto, Ontario, Canada, June 8–13, 1997.

9. Pavlish, J.H.; Gerlach, T.R.; Zygarlicke, C.J.; Pflughoeft-Hassett, D.F. Mitigation of Air Toxics from Lignite Generation Facilities ; Final Report; Energy & Environmental Research Center: Grand Forks, ND, Oct 1995.

10. U.S. Environmental Protection Agency. Report to Congress—Wastes from the Combustion of Fossil Fuels: Vol. 2—Methods, Findings, and Recommendations ; EPA 530-R-99-010; EPA Office of Solid Waste and Emergency Response, Washington, DC, 1999.21 11. DeVito, M.S.; Rosenhoover, W.A. Flue Gas Hg Measurements from Coal-Fired Boilers Equipped with Wet Scrubbers. In Proceedings of the Air and Waste Management Association 92nd Annual Meeting and Exhibition ; St. Louis, MO, June 20–24, 1999.

12. DeVito, M.S. The Effect of Low-NO

x Burner Operation on Mercury Emissions, Speciation, and Removal at a Coal-Fired Boiler Equipped with Wet FGD. Presented at the 17th Annual Pittsburgh Coal Conference, Pittsburgh, PA, Sept 11–14, 2000.

13. Pavlish, J.H.; Sondreal, E.A.; Mann, M.D.; Olson, E.S.; Galbreath, K.C.; Laudal, D.L.; Benson, S.A. Status Review of Mercury Cont rol Options for Coal-Fired Power Plants.

Fuel Proc. Technol

. 2003

, 82 , 89–165.

14. Chu, P.; Goodman, N.; Behrens, G.; Roberson, R. Total and Speciated Mercury Emissions

from U.S. Coal-Fired Power Plants. In Proceedings of the Air Quality II: Mercury, Trace Elements, and Particulate Matter Conference ; McLean, VA, Sept 19–21, 2000; Paper

A34.

15. Laumb, J.D.; Jensen, R.R.; Benson, S.A. Information Collection Request for Mercury: or Relation Analysis of Coal and Power Plant Data. In Proceedings of the Air Quality II: Mercury, Trace Elements, and Particulate Matter Conference ; McLean, VA, Sept 19–21, 2000; Poster Paper 15.

16. Senior, C.L.; Helble, J.J.; Sarofim, A.F. Predicting the Speciation of Mercury Emissions

from Coal-Fired Power Plants. In Proceedings of the Air Quality II: Mercury, Trace Elements, and Particulate Matter Conference ; McLean, VA, Sept. 19–21, 2000; Paper A5-2.

17. Olson, E.S.; Laumb, J.D.; Benson, S.A.; Dunham, G.E.; Sharma, R.K.; Mibeck, B.A.; Miller, S.J.; Holmes, M.J.; Pavlish, J.H. An Improved Model for Flue Gas–Mercury

Interactions on Activated Carbons. In Proceedings of the Combined Power Plant Air Pollutant Control Mega Symposium ; Washington, DC, May 19–22, 2003.

18. Olson, E.S.; Sharma, R.K.; Miller, S.J.; Dunham, G.E. Identification of the Breakthrough Oxidized Mercury Species from Sorbents in Flue Gas. In Proceedings of the Specialty Conference on Mercury in the Environment ; Minneapolis, MN, Sept. 15–17, 1999; pp 121–126.

19. Olson, E.S. Energy & Environmental Research Center, Grand Forks, ND. Personal communication, June 27, 2001.

20. Galbreath, K.C.; Zygarlicke, C.J.; Toman, D.L.; Schulz, R.L. Effects of NO

x and Alpha

Fe 2 O 3 on Mercury Transformations in a 7-kW Coal Combustion System. In Proceedings of the Air and Waste Management Association 94th Annual Meeting and Exhibition ; Orlando, FL, June 24–28, 2001; Paper 767.22 21. Galbreath, K.C.; Zygarlicke, C.J.; Toman, D.L. Mercury–Flue Gas–Fly Ash Interactions.

In Proceedings of the Specialty Conference on Mercury in the Environment ; Minneapolis, MN, Sept 15–17; Air and Waste Management Association, Pittsburgh, PA, 1999; pp 141–

151.

22. Butz, J.; Albiston, J. Use of Fly Ash Frac tions from Western Coals for Mercury Removal

from Flue Gas Streams. In Proceedings of the Air Quality II: Mercury, Trace Elements, and Particulate Matter Conference ; McLean, VA, Sept 19–21; 2000; Paper A4-5.

23. Senior, C.; Bustard, C.J.; Durham, M.; Bald rey, K. Characterization of Fly Ash from FullScale Demonstration of Sorbent Injection for Mercury Control on Coal-Fired Power

Plants. In Proceedings of the Air Quality III: Mercury, Trace Elements, and Particulate Matter Conference ; Arlington, VA, Sept 9–12, 2002; Paper A2-05.

24. Butz, J.R.; Broderick, T.E.; Lovell, J.S.; Turchi, C.S. Amended Silicates: High-Capacity Mercury Sorbent Unaffected by Acid Gases. In Proceedings of the Air Quality III: Mercury, Trace Elements, and Particulate Matter Conference ; Arlington, VA, Sept 9–12, 2002; Paper A4-06.

25. Nelson Jr., S.; Zhou, Q.; Miller, J. Novel Duct-Injection Mercury Sorbents. In Proceedings of the Air Quality III: Mercury, Trace Elements, and Particulate Matter Conference ; Arlington, VA, Sept 9–12, 2002; Paper A4-08.

26. Brown, T.D.; Smith, D.N.; Hargis, R.A.; O’Dowd, W.J. Mercury Measurement and Its Control: What We Know, Have Learned, and Need to Further Investigate. J. Air Waste Manage. Assoc. 1999

, June , 1–97.

27. EPRI. An Assessment of Mercury Emissions from U.S. Coal-Fired Power Plants ; EPRI Report No. 1000608; EPRI: Palo Alto, CA, Oct 2000.

28. U.S. Environmental Protection Agency. Mercury Study Report to Congress ; EPA-452/R97-003; U.S. EPA Office of Air Quality Pl anning and Standards, U.S. Government Printing Office: Washington, DC, Dec 1997.

29. Holmes, M.J.; Redinger, K.E.; Evans, A.P.; Nolar, P.S. Control of Mercury in Conventional Flue Gas Emissions Control Systems. In Proceedings of the 4th International Conference on Managing Hazardous Air Pollutants ; Washington, DC,
Nov 12–14, 1997.

30. Amrhein, G.T.; Holmes, M.J.; Bailey, R.T.; Kudlac, G.A.; Downs, W.; Madden, D.A. Advanced Emissions Control Development Program ; Phase III—Approved Final Report; U.S. Department of Energy Contract DE-FC22-94PC94251, July 1999.23 31. Kudlac, G.A.; Amrhein, G.T. Enhanced Mercury Control for Coal-Fired Boilers. In Proceedings of the 17th Annual Pittsburgh Coal Conference ; Pittsburgh, PA, Sept 11–14, 2000; Paper 25-2.

32. Carey, T.R.; Skarupa, R.C.; Hargrove O.W., Jr. Enhanced Control of Mercury and Other HAPs by Innovative Modification to Wet FGD Processes ; Phase I Report for U.S. Department of Energy Agreement No. DE-AC22-95PC95260, Aug 28, 1998.

33. Richardson, C.F.; Blythe, G.M.; Rhudy, R.G.; Brown, T.D. Enhanced Control of Mercury by Wet FGD Systems. Presented at the Air and Waste Management Association 93rd Annual Meeting and Exhibition, Salt Lake City, UT, 2000; Paper No. AE1B 43.

34. Blythe, G.M.; Carey, T.R.; Richardson, C.F.; Meserole, F.B.; Rhudy, R.G.; Brown, T.D. Enhanced Control of Mercury by Wet Flue Gas Desulfurization Systems. Presented at the Air and Waste Management Association 92nd Annual Meeting and Exhibition, St. Louis,
MO, June 20–24, 1999.

35. Hargrove O.W., Jr.; Carey, T.R.; Rhudy, R.G.; Brown, T.D. Enhanced Control of Mercury by Innovative Modifications to Wet FGD Processes. In Proceedings of the Air and Waste Management Association 89th Annual Meeting and Exhibition ; Nashville, TN, June 23–28, 1996; Paper No. 96-WP64B.02.

36. Livengood, C.D.; Mendelsohn, M.H.; Huang, H.S.; Wu, J.M. Development of Mercury Control Techniques for Utility Boilers. In Proceedings of the Air and Waste Management Association 88th Annual Meeting; San Antonio, TX, 1995; Paper MP21.07.

37. Mendelsohn, M.H.; Livengood, C.D. A New Method for Oxidation of Gaseous, Elemental Mercury. In Proceedings of the Air and Waste Management Association Specialty Conference on Mercury in the Environment ; Minneapolis, MN, Sept 15–17, 1999.

38. Sondreal, E.A.; Benson, S.A.; Pavlish, J.H.; Galbreath, K.C.; Zygarlicke, C.J.; Thompson, J.S.; McCollor, D.P.; Crocker, C.R.; Lillemoen, C.M.; Mann, M.D.; Jensen, R.R.; Weber,

G.F. Center for Air Toxic Metals Final Technical Report Volume 3 ; Final Technical Report for U.S. Environmental Protection Agency Assistance Agreement R824854; Energy & Environmental Research Center: Grand Forks, ND, Sept 2000.

39. Berland, T.D.; Pfughoeft-Hassett, D.F.; Dockter, B.A.; Eylands, K.E.; Hassett, D.J.; Heebink, L.V. Review of Handling and Use of FGD Material ; Final Report for U.S. Department of Energy; Energy & Environmenta l Research Center: Grand Forks, ND, April

2003.

40. Hassett, D.J.; Pflughoeft-Hassett, D.F. Partitioning of Trace Elements During the Air Oxidation of Scrubber Sludge. Presented at the 5th International Conference on FGD and Synthetic Gypsum, Toronto, Ontario, Canada, May 11

− 14, 1997.24 41. Senior, C.; Bustard, C.J.; Durham, M.; Starns , T.; Baldrey, K. Characterization of Fly Ash from Full-Scale Demonstration of Sorbent Injection for Mercury Control on Coal-Fired

Power Plants. In Proceedings of the Air Quality IV: Mercury, Trace Elements, and Particulate Matter Conference ; Arlington, VA, Sept 22–24, 2003.

42. Gustin, M.S.; Giglini, A.; Piper; J.; Ladwi g, K. Mercury Releases from Coal Fly Ash. In Proceedings of the Air Quality III: Mercury, Trace Elements, and Particulate Matter Conference; Arlington, VA, Sept 9–12, 2002.

43. Gustin, M.S.; Ladwig, K. An Assessment of the Significance of Mercury Release from Coal Fly Ash. J. Air Waste Manage. Assoc

. 2004

, 54 , 320–330.

44. Ladwig, K. Fate of Mercury in Coal Combustion Products. Presented at the Mercury Control Technology R&D Program Review Meeting, Pittsburgh, PA, Aug 12–13, 2003.

45. Pavlish, J.H.; Holmes, M.J.; Benson, S.A.; Crocker, C.R.; Olson, E.S.; Galbreath, K.C.; Zhuang, Y.; Pavlish, B.M. JV Task 45 – Mercury Control Technologies for Electric Utilities Burning Lignite Coal, Phase I Bench- and Pilot-Scale Testing ; Final Report; Energy & Environmental Research Center: Grand Forks, ND, 03-EERC-10-03.

46. Hassett, D.J. Unpublished data, 2001.

47. Pflughoeft-Hassett, D.F. Mercury Impacts on By-Products. Presented at the Mercury Control Technology R&D Program Review Meeting in Pittsburgh, PA, July 14–15, 2004.

48. Kazonich, G.; Kim, A.G.; Dahlberg, M.D. Comparison of Leaching Results for Three High Mercury Fly Ash Samples. In Proceedings of the Air Quality IV: Mercury, Trace Elements, and Particulate Matter Conference ; Arlington, VA, Sept 22–24, 2003.

49. Kim, Ann. Aqueous Stability of Mercury on Fly Ash. Presented at the Mercury Control Technology R&D Program Review Meeting in Pittsburgh, PA, July 14–15, 2004.

50. Gale, T.K. Mercury Control with Calcium-Based Sorbents and Oxidizing Agents; Southern Research Institute – Quarterly Report for U.S. Department of Energy Contract DE-PS26- 02NT41183; April 1, 2003 – June 30, 2003.

51. Richardson, M. Mercury Stability in FGD By-Products. Presented at Hg Control – The Effects on By-Products: What Do We Know and Where Do We Go? NETL Workshop, Pittsburgh, PA, March 19, 2002.

52. Golden, D. Effect of Mercury Controls on By-Product Use. Presented at the American Coal Ash Association 15th International Symposium on Management and Use of Coal Combustion Products, St. Petersburg, FL, Jan 27–30, 2003.25 53. Withum, J.A.; Schwalb, A.M.; Statnick, R. M. Characterization of Coal Combustion ByProducts for the Re-Evolution of Mercury into Ecosystems. In Proceedings of the Air Quality III: Mercury, Trace Elements, and Particulate Matter Conference ; Arlington, VA, Sept 9–12, 2002.

54. Schwalb, A.M.; Withum, J.A. The Evolution of Mercury from Coal Combustion Materials and By-Products. Presented at the Mercur y Control Technology R&D Program Review Meeting, Pittsburgh, PA, Aug 12–13, 2003.

55. Carey, T.R.; Richardson, C.F.; Chang, R. Stability of Mercury Captured on Sorbent Surfaces. Presented at the Air and Waste Management Association 92nd Annual Meeting and Exhibition, St. Louis, MO, June 20–24, 1999.

56. Hassett, D.J.; Heebink, L.V. Long-Term Mercury Release. In Proceedings of the 2003 International Ash Utilization Symposium ; Lexington, KY, Oct 20–22, 2003.

57. Butz, J.; Smith, J. Coal Fly Ash as a Sorbent for Mercury. In Proceedings of the Western Region Ash Group Fall Meeting ; Denver, CO, Nov 10, 1999.

58. Hassett, D.J.; Heebink, L.V.; Zacher, E.J. Determination of Organomercury Compounds from Microbiologically Medicated Merc ury Release Experiments Using Gas Chromatography with SPME Sample Introduc tion after Boroethylation, Boropropylation, or Borophenylation. Presented at the Combined Power Plant Air Pollutant Control Mega Symposium, Washington, DC, Aug 30 – Sept 2, 2004.MERCURY INFORMATION CLEARINGHOUSE

QUARTER 9 – MERCURY INFORMATION CLEARINGHOUSE FINAL REPORT

ACKNOWLEDGMENT AND DISCLAIMERS

This report was prepared under contract with the Canadian Electricity Association (CEA) and supported by funding from that organization, the Canadi an Council of Ministers of the Environment, the U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) Cooperative Agreement No. DE-FC26-98FT40321, and the Center for Air Toxic Metals ® (CATM ® ) Program at the Energy & Environmental Research Center (EERC). However, any opinions, findings, conclusions, or recommendations expressed herein are the author(s) a nd do not necessarily reflect the views of any of the above-mentioned organizations.

EERC DISCLAIMER

LEGAL NOTICE This research report was prepared by the EERC, an agency of the University of North Dakota, as an account of work for CEA and supported by funding from that organization, DOE NETL, and the CATM Program at the EERC. Because of the research nature of the work performed, neither the EERC nor any of its employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily cons titute or imply its endorsement or recommendation by the EERC.

U.S. GOVERNMENT DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government, nor any agency thereof, nor any of their employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, appara tus, product, or process disclosed or represents that its use would not infringe privately owned rights. Re ference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed he rein do not necessarily state or reflect those of the United States Government or any agency thereof.

REPORT AVAILABILITY

This report is available to the public from th e National Technical Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161; phone orders accepted at (703) 487-4650 and the CEA Mercury Program Web site (www.ceamercuryprogram.ca).i TABLE OF CONTENTS

LIST OF FIGURES ................................................................................................................ ....... iv

LIST OF TABLES................................................................................................................. ......... v

EXECUTIVE SUMMARY ........................................................................................................... vi

INTRODUCTION ................................................................................................................... ....... 1

CEA MERCURY PROGR AM OVERVIEW................................................................................. 3 Laboratory Quality Assurance Assessment........................................................................... 4 Mercury Research and Development .................................................................................... 4 Mercury-Sampling and Analysis Program............................................................................ 5 CEA Mercury Program Coal Data ........................................................................................ 5 CEA Mercury Program Ash Data ......................................................................................... 7 CEA Mercury Program Flue Gas Data ................................................................................. 8 Mercury Policy................................................................................................................. ..... 9

References ..................................................................................................................... ...... 12

SORBENT CONTROL TECHNOLOGIES FOR MERCURY CONTROL AND MERCURY CONTROL FIELD DEMONSTRATIONS (QUARTER 1 AND QUARTER 6 REPORTS) ..... 13 Field Demonstrations of Carbon Injection.......................................................................... 13 Field Demonstrations Using Ch emically Treated Carbons................................................. 19

Economics of ACI............................................................................................................... 20

References ..................................................................................................................... ...... 20

MERCURY MEASUREMENT ( QUARTER 2 REPORT).......................................................... 23 Additional Experience with 40 CFR, Part 75, Appendix K Specifications ........................ 24 QA/QC Requirements for Mercury Measurement RATAs................................................. 24 Additional Experience Gained with Next-Generation Continuous Mercury Monitors ...... 25 An Instrument-Based Reference Method for Mercury Measurement................................. 25

ADVANCED AND DEVELOPMENTAL MERCURY CONTROL TECHNOLOGIES (QUARTER 3 REPORT)............................................................................................................. . 27 Pretreatment of the Coal to Remove Mercury .................................................................... 27

Combustion Modification and in Situ Generation of Sorbents........................................... 28 Non-Carbon-Based Sorbent, Amended Silicates ................................................................ 29

Continued . . .ii TABLE OF CONTENTS (continued)

Stationary Mercury Traps Positioned in the Flue Gas Stream............................................ 29

MerCAPTM................................................................................................................. 29 W.L. Gore & Associates, Inc.-Promoted Felt Filter Bag Inserts............................... 30

EnviroScrub Pahlman Process................................................................................... 30

Combined Oxidation of NO

x and Mercury................................................................ 31

LoTO

x TM .................................................................................................................... 31 ECO/Powerspan......................................................................................................... 31 Mercury Control with the Advanced Hybrid TM Filter ......................................................... 32

RERELEASE OF MERCURY FROM COAL COMBUSTION BY-PRODUCTS (QUARTER 4 REPORT)............................................................................................................. . 33 Stability of Mercury on CCBs............................................................................................. 33 Leaching ....................................................................................................................... ....... 35 Vapor Release .................................................................................................................. ... 35 Elevated Temperature Vapor-Phase Rerelease.......................................................... 36 Ambient Temperature Vapor-Phase Rerelease.......................................................... 36 Microbiologically Medi ated Release .................................................................................. 37 Field Studies of Mercury Releases...................................................................................... 37 Disposal Site Water Evaluations ............................................................................... 37 Field Vapor-Phase Releases ...................................................................................... 38 Rerelease of Mercury from CCBs in Select Utilization Applications ................................ 39 Summary ........................................................................................................................ ..... 40

References ..................................................................................................................... ...... 41

MERCURY FUNDAMENTALS ( QUARTER 5 REPORT) ....................................................... 44

Flue Gas Effects ............................................................................................................... ... 44

Carbon Structure Effects ..................................................................................................... 44

Acid Promotion Effects....................................................................................................... 45 Mercury Oxidation Mechanism .......................................................................................... 47 Halogenated Carbons .......................................................................................................... 47 Potential for More Effective Capture.................................................................................. 49

References ..................................................................................................................... ...... 50

HEALTH ASPECTS OF MERCURY EMISSIONS (QUARTER 5 REPORT).......................... 52 Environmental Hg ............................................................................................................... 56

References ..................................................................................................................... ...... 57

Continued . . .iii TABLE OF CONTENTS (continued)

COMMERCIALIZATION ASPECTS OF SORBENT INJECTION TECHNOLOGIES IN CANADA (QUARTER 8 REPORT)............................................................................................ 61

UPCOMING EVENTS................................................................................................................ . 63

AUTHORS........................................................................................................................ ............ 64

CONTACT INFO RMATION....................................................................................................... 64iv LIST OF FIGURES

1 Mercury removal as a function of ACI rate at three sites ................................................... 18

2 Field leachate – me rcury speciation.................................................................................... 38

3 Overview of mercury flue gas interactions on an activated carbon sorbent ....................... 45

4 Breakthrough curves for high and low acid gas.................................................................. 46

5 Mercury and acid gas-binding mechanism at carbon edge ................................................. 47

6 Oxidation mechanism – carbenium ion oxidant.................................................................. 48

7 Mecury oxidation mechanis m for chlorinated carbon......................................................... 49

8 Molar relationships between mercury and selenium concentrations in seafood................. 54

9 Molar ratio of mercury:selenium concentrations in seafood............................................... 54

10 Molar ratio of selenium:mercury concentrations in seafood............................................... 55

11 Relative effects of whale vs. fish consumption................................................................... 56v LIST OF TABLES

1 CEA Mercury Program Coal Data ........................................................................................ 6

2 CEA Mercury Program Ash Data ....................................................................................... 10

3 CEA Mercury Program Flue Gas Data ............................................................................... 11

4 Mercury Control Demonstration Projects F unded by the U.S. Department of Energy ...... 14

5 Additional O&M Costs for Canadian Power Plants as a Result of Adding ACI................ 21

6 Total Mercury in CCBs and Mercury-Leaching Results Reported by Various Groups ..... 34

7 Summary of Field Mercury Flux Data Presented by Xin et al............................................ 39

8 Mercury Emission from Dry-Curing Concretes.................................................................. 40vi MERCURY INFORMATION CLEARINGHOUSE

QUARTER 9 – MERCURY INFORMATION CLEARINGHOUSE FINAL REPORT

EXECUTIVE SUMMARY

The Canadian Electricity Association (C EA) identified a need and contracted the Energy & Environmental Research Center (EERC) to create and maintain an information clearinghouse on global research and development activities related to mercury emissions from coal-fired electric utilities. With the support of CEA, the Center for Air Toxic Metals ® (CATM ® ) Affiliates, and the U.S. Department of Energy (DOE), the EERC developed comprehensive quarterly information updates that provide a detailed assessment of developments in the various areas of mercury monitoring, control, policy, and re search. A total of eight topical reports were completed and are summarized and updated in this final CEA quarterly report. The original quarterly reports can be viewed at the CEA Web site (www.ceamercuryprogram.ca).

In addition to a comprehensive update of previous mercury-related topics, a review of results from the CEA Mercury Program is provide d. Members of Canada’s coal-fired electricity generation sector (ATCO Power, EPCOR, Ma nitoba Hydro, New Brunswick Power, Nova Scotia Power Inc., Ontario Power Generation, SaskPower, and TransAlta) and CEA, have compiled an extensive database of information from stack-, coal-, and ash-sampling activities. Data from this effort are also available at the CEA Web site and have provided critical information for establishing and reviewing a mercury standard for Canada that is protective of environment and public health and is cost-effective. Specific goals outlined for the CEA mercury program included the following:

1. Improve emission inventories and develop management options through an intensive 2-year coal-, ash-, and stack-sampling program

2. Promote effective stack testing through the development of guidance material and the support of on-site training on the Ontario Hydro method for employees, government representatives, and contractors on an as-needed basis

3. Strengthen laboratory analytical capabilities through analysis and quality assurance

programs

4. Create and maintain an information clearinghouse to ensure that all parties can keep informed on global mercury research and development activities

CEA members committed to a program of quarterly sampling and reporting of mercury in coal, residue, and stack emissions. Over the past 2 years, a large data set of approximately 35,000 data points has been generated that characterizes the range and variability of mercury present in the coal and the resulting variability of mercury present in by-products and stack emissions. Quarterly reports from each of the member companies provide detailed data on coal characteristics, ash, and stack gas measurements and can be viewed atvii www.ceamercuryprogram.ca. Through this sample and analysis effort, CEA met the goal to improve emission inventories to support mercury management strategies (Goal 1) and provide member utilities experience with mercury measurement methods (Goal 2). The findings of this effort have helped to reduce the uncertainty around mercury emissions and concentrations in coal and combustion by-products and provided critical information for establishing and reviewing a mercury standard for Canada.

In conjunction with quarterly sampling, a laboratory quality assurance and quality control program was conducted. In general the goal of improving and validating laboratory proficiency in mercury analysis (Goal 3) was achieved through the laboratory round-robin. Through this effort, quality assurance of lab procedures and methods was achieved, and a database of coal

characteristics from across Canada was enhanced.

Finally, through the compilation of this report and the previous eight quarterly Information Clearinghouse Reports, the goal of creating and maintaining a database of global mercury research has been achieved (Goal 4).1 MERCURY INFORMATION CLEARINGHOUSE

QUARTER 9 – MERCURY INFORMATION CLEARINGHOUSE FINAL REPORT

INTRODUCTION

The Canadian Electricity Association (C EA) identified a need and contracted the Energy & Environmental Research Center (EERC) to create and maintain an information clearinghouse on global research and development activities related to mercury emissions from coal-fired electric utilities. With the support of CEA, the Center for Air Toxic Metals ® (CATM ® ) Affiliates, and the U.S. Department of Energy (DOE), the EERC developed comprehensive quarterly information updates that provide a detailed assessment of developments in the various areas of mercury monitoring, control, policy, and research.

In order to adequately address the many topics and provide the detail necessary for the various stakeholders to make informed decisions, selected topics were discussed in detail in each quarterly report. Issues related to mercury from coal-fired utilities include the general areas of measurement, control, policy, and transformations. Specific topics that have been addressed in previous quarterly reports include the following:

• Quarterly 1 – Sorbent Control Technologies for Mercury Control

• Quarterly 2 – Mercury Measurement

• Quarterly 3 – Advanced and Developmental Mercury Control Technologies

• Quarterly 4 – Rerelease of Mercury from Coal Combustion By-Products

• Quarterly 5 – Mercury Fundamentals

• Quarterly 6 – Mercury Control Field Demonstrations

• Quarterly 7 – Mercury Regulations in the United States: Federal and State

• Quarterly 8 – Commercialization Aspects of Sorbent Injection Technologies in Canada

In this last of nine quarterly reports, an update of these mercury issues is presented that includes a summary of each topic, with recent information pertinent to advances made since the quarterly reports were originally presented. As a result of significant advances made in some areas of mercury research and development, several of the updated reports contain a comprehensive and detailed discussion, as is the case for Quarterly 4 – Rerelease of Mercury from Coal Combustion By-Products, and Quarte rly 3 – Advanced and Developmental Mercury Control Technologies. For other topics; Quarter 8– Commercialization Aspects of Sorbent Injection Technologies in Canada; for example, only limited new information is available and a brief summary of the original topical reports is provided. Each of the updated summary reports is provided in a section of this final Quarter 9 report.

In addition to a comprehensive update of previous mercury-related topics, a review of results from the CEA Mercury Program is provide d. Members of Canada’s coal-fired electricity generation sector are committed to reducing mercury releases and, with CEA, have compiled an extensive database of information from stack-, coal-, and ash-sampling activities. Data from this2 effort are available at the CEA Web site ( www.ceamercuryprogram.ca) and has provided critical information for establishing and reviewing a mercury standard for Canada that is protective of environment and public health and is cost-effective.3 QUARTER 9 FOCUS: MERCURY INFORMATION CLEARINGHOUSE FINAL

REPORT

CEA MERCURY PROGRAM OVERVIEW

CEA with the cooperation of eight coal-fired power generation companies in Canada joined forces to develop and implement the CEA Mercury Program designed to improve the information base around the measurement and control of mercury emissions. These utilities included ATCO Power, EPCOR, Manitoba Hydr o, New Brunswick Power, Nova Scotia Power Inc. (NSPI), Ontario Power Generation (OPG), SaskPower, and TransAlta. The focus of the program is to improve the understanding of both human and natural sources of mercury releases, mercury movement through the environment, effects on human health, and the best ways to minimize these impacts. The coal-fired electricity generation industry is one of the largest point sources of mercury emissions currently and is working with governments, researchers, and other stakeholders to help develop effective and efficient ways of reducing these emissions.

The first priority of the CEA Mercury Program is to reduce the uncertainty of mercury measurement and emission control. The key components of the program, which have been ongoing for almost 3 years, include a laboratory quality assurance round-robin, research and development, and a mercury-sampling and analysis program. Activities continue in all of these areas; however, significant progress has been made, and the findings have provided criticalinformation in support of the Canada-Wide Standard (CWS) for mercury from the coal-firedelectricity generating sector.

When the program was initiated, several goals were outlined. Through the laboratory round-robin, research and development, and sampling and analysis activities these goals have largely been met. Goals originally outlined included the following:

1. Improve emission inventories and the development of management options through an intensive 2-year coal-, ash-, and stack-sampling program

2. Promote effective stack testing through the development of guidance material and the support of on-site training on the Ontario Hydro method for employees, government representatives, and contractors on an as-needed basis

3. Strengthen laboratory analytical capabilities through analysis and quality assurance

programs

4. Create and maintain an information clearinghouse to ensure that all parties can keep informed on global mercury research and development activities4 Laboratory Quality Assurance Assessment

The laboratory quality assurance assessment was conducted to verify and ensure the accuracy and precision of mercury analysis in coal, ash, and scrubber effluent samples from coal-fired utilities. Proper analysis, by Canadian laboratories, of mercury in coal and ash samples is critical to accurately evaluate the fate of me rcury across a coal-fired unit. Concentrations of mercury in coal, ash, scrubber effluents, and stack gas samples tend to be very low, near the detection limits in some cases, making consistent, reliable results difficult to achieve. To address these challenges, CEA member companies conducted a two-phase program. In the first phase, performance of 13 laboratories was assessed over a 6-month period by analyzing standard samples and comparing results with known values. Analysis included mercury, total chlorine, moisture, sulfur, total carbon (ash), and heating value (coal). Results were reviewed statistically to determine the laboratory’s competency to accurately analyze the parameters in specific coals and ashes as well as limits of quantification. According to the Mercury Laboratory Round-Robin Project Canadian Council of Ministers of the Environment (CCME)–CEA Project 257-2003 Phase 1 CRM/RM Sample Report, nine of the 13 laboratories produced mercury values at least as good as the reference confidence limit, and “Canadian utilities produce mercury results of exceptional quality for coal...” (1).

Phase II consisted of a longer-term quality control and quality assurance effort. During Phase II, quarterly analysis was conducted that included reference coals and coal samples representative of fuel burned by Canadian utilities. Reference coal analysis provided ongoing measurement of laboratory performance relative to known standards. Analysis of utility coal samples provided valuable results from which to build a database of Canadian coal characteristics, which, in turn, supported the mercury emission standards development. Phase II of the laboratory quality assurance assessment builds upon the Coal and Ash Sampling Proficiency Exchange (CANSPEX) program, wh ich was developed in 1990 to provide quality assurance management of coal analysis.

In general the goal of improving and validating laboratory proficiency in mercury analysis (Goal 3) was achieved through the laboratory quality assurance assessment. Through this effort, quality assurance of lab procedures and methods was achieved, and a database of coal

characteristics from across Canada was enhanced.

Mercury Research and Development

Significant research and technology development has been ongoing in Canada, the United States, and internationally. Through a variety of governmental and commercial collaborations, CEA member companies have been conducting research on mercury as well as other emissions and greenhouse gases from coal-fired boilers.

Through the compilation of this report and the previous eight quarterly Information Clearinghouse Reports, the goal of creating and maintaining a database of global mercury research has been achieved (Goal 4).5 Mercury-Sampling and Analysis Program

One of the most important factors influencing mercury regulation is an accurate understanding of mercury fate across the process, both at specific facilities and in general for the coal-fired electric generating sector. In the United States, this understanding came from the Information Collection Request (ICR) conducted between November 1998 and July 2000. To support U.S. Environmental Protection Agency (EPA) regulation development, an intensive sampling and analysis program was undertaken to determine mercury values in coal, by-product effluents (bottom ash, fly ash, scrubber effluent ), and stack emissions. Sampling activities were conducted at facilities across the United States of various emission control configurations and fuel types. Results from these data were compiled and helped develop a better understanding of how mercury behaves in these systems and to set priorities for control.

In Canada, the CEA Mercury Program has stated that “the first priority in managing

mercury is to improve the inventory of mercury emissions from coal-fired power plants across the country” (2). In support of ongoing and histori cal efforts to quantify mercury emissions from coal-fired utilities, CEA members committed to a program of quarterly sampling and reporting of mercury in coal, residue, and stack emissions. Over the past 2 years, a large data set has been generated that characterizes the range and variability of mercury present in the coal and resulting variability of mercury present in by-products and st ack emissions. Quarterly reports from each of the member companies provide detailed data on coal characteristics, ash, and stack gas measurements and can be viewed at www.ceamercuryprogram.ca.

The mercury-sampling and analysis program was designed to function in cooperation with the laboratory quality assurance assessment to provide accurate and precise information. The findings of this effort have helped to reduce the uncertainty around mercury emissions and concentrations in coal and combustion by-products and provided critical information for establishing and reviewing a mercury standard for Canada and finding cost-effective and efficient management options. Data generated from this sampling and analysis program have helped to meet CEA’s goal (Goal 1) to improve emission inventories to support mercury management strategies and provided member utilities experience with mercury measurement methods (Goal 2). A brief summary of the data compiled through this effort is provided in the following section.

CEA Mercury Program Coal Data

The mercury emitted from coal-fired power plants, evolves directly from the mercury present in the coal at the time of firing. Typically, mercury is present in the coal in the tens of parts-per-billion range; however, it can vary significantly depending upon the type of coal and its source. A summary of results from sampling conducted by Canadian utilities is provided in Table 1 and shows that across Canada, mercury in the coal ranges from 0.007–0.640 mg/kg (ppm), with typical concentrations around 0.05–0.09 mg/kg. The data presented in Table 1 comprise average coal characteristics from sampling activities conducted at several collaborating CEA member companies. In general, the data are a compilation of many coal analyses conducted6Table 1. CEA Mercury Program Coal DataPower PlantMW Coal TypeBlendRatioMoisture,%Ash,% (dry)Mercury,mg/kg (dry)Mercury,Min/Max, mg/kg1Chloride,mg/kg (dry)Chlodine,Min/Max,mg/kg*ATCO PowerBattle River – 5 375 sub-b. NA24.56 16.81 0.040 0.023/0.063 28 14/62Sheerness – 1 and 2 767 sub-b. NA 24.59 18.53 0.060 0.034/0.089 29 22/49EPCOR PowerGenesee – 1 and 2 820 sub-b. NA 18.57 21.62 0.043 0.029/0.066 105 33/1188Manitoba HydroBrandon GS – 5 105 sub-b. NA 10.83 6.28 0.077 0.032/0.172 18 6/46New Brunswick PowerBelledune 490 bit. NA 11.08 10.11 0.044 0.018/0.095 245 122/468NSPILingan – 1 and 2 300 petc./bit.21/79 10.94 7.36 0.053 0.023/0.160 378 23/1558Lingan – 3 and 4 300 petc./bit.21/79 10.94 7.36 0.053 0.023/0.160 378 23/1558Point Aconi – 1 165 petc./bit. 75/25 7.83 2.75 0.023 0.007/0.071 294 <15/4600Point Tupper 150 petc./bit. 18/82 10.65 6.20 0.047 0.012/0.114 297 29/1600Trenton – 5 150 petc./bit. 4/968.13 8.39 0.100 0.035/0.195 816 <14/1500Trenton – 6 160 petc./bit. 26/74 6.57 17.93 0.039 0.012/0.087 756 160/2000OPGAtikokan 215 lig NA 34.19 15.26 0.089 0.060/0.136 25 10/622Lambton – 1 and 2 1000 bit. NA 8.72 9.24 0.063 0.018/0.640 641 207/1564Lambton – 3 and 4 505 each bit.NA 6.75 8.44 0.0960.063/0.322 861 427/1060Nanticoke – 5, 6, and 7 500 each sub-b./bit. 70/30 21.83 7.930.066 0.039/0.102 471 22/2001Thunder Bay – 2 and 3 310 lig./sub-b.80/20 31.02 12.39 0.084 0.010/0.310 17 10/82TAUSundance – 5 and 6 760 sub-b. NA 19.14 20.92 0.069 0.040/0.100 70 17/281SaskPower2Boundary Dam – 1 66 lig. NA 32.72 13.54 0.073 0.055/0.098 10 8.32/11.85Boundary Dam – 2 66 lig. NA 32.91 13.45 0.072 0.055/0.097 10 8.45/11.46Boundary Dam – 3 150 lig. NA 32.82 13.53 0.073 0.053/0.098 10 8.45/11.44Boundary Dam – 4 150 lig. NA 32.39 13.62 0.075 0.055/0.098 10 8.54/10.77Boundary Dam – 5 150 lig. NA 32.37 13.70 0.076 0.052/0.109 10 8.69/10.53Boundary Dam – 6 300 lig. NA 32.44 13.72 0.073 0.052/0.093 10 8.76/10.53Poplar River – 1 300 lig NA 36.84 13.69 0.090 0.068/0.114 12 10.36/13.2Poplar River – 2 300 lig. NA 36.83 13.72 0.089 0.068/0.114 12 10.44/13.2Shand 305 lig. NA 31.97 13.88 0.078 0.044/0.119 9 6.88/10.6Note: bit.=bituminous, sub-b.=sub-bituminous, lig.=lignite, petc.=petcoke1Quarterly Data Reports2SaskPower coal and ash results are as-received, not dry basis.7 since the effort began in the fall of 2002, with the maximum and minimum mercury and chlorine values presented to illustrate the range across Canadian fuels.

Based on the mercury data presented in Table 1, it is clear that variability exists both among the various power plants and within coal samples from a single facility. It is reasonable to expect similar relative variability in stack emissions, with additional variability due to the range of effectiveness of electrostatic precipitators (ESPs), fabric filters (FFs), and flue gas desulfurization (FGD) units at capturing mercury.

CEA Mercury Program Ash Data

Mercury present in the coal is volatilized during combustion and exits the boiler with the flue gas. As the gas cools in the preheater and ductwork, opportunities for the mercury to react or adsorb to other constituents in the flue gas exist. One pathway by which mercury finds its way out of the flue gas is by adsorbing to fly ash. Typically, ash with relatively high levels of unburned carbon exhibit the highest mercury concentration. Particulate control devices, therefore, become mechanisms for mercury capture depending upon the flue gas characteristics, ash composition, and operating conditions. Typically, mercury is not found in large quantities in bottom ash because of the high temperature in the boiler. This is consistent with data collected from Canadian utilities and presented in Table 2. The concentration of mercury in bottom ash ranged from less than 0.003 to 0.228 mg/kg; however, the average value was 0.02 mg/kg.

Mercury present in fly ash was typically one or two orders of magnitude higher than measured in the bottom ash. The concentration of mercury in the fly ash ranged from less than 0.003–0.847 mg/kg. Several plants, including OPG’s Nanticoke Units 5–7 and Lambton Units 1–4, had the highest mercury concentration in the ash. At Nanticoke Units 5–7, high levels of mercury in the fly ash, 0.637, could be related to the higher chloride concentration of the fuel. Table 1 shows an average chloride concentration for these fuels of 471 mg/kg for Units 5, 6, and 7. At chloride levels in the mid-100s, higher mercury concentrations are sometimes observed in the ash. Based on the present understanding of mercury fundamentals, it is believed that the presence of halogens in the flue gas improves the adsorption of mercury to carbon and/or ash, resulting in greater mercury capture and higher concentrations in hopper ash. This is consistent with the high carbon content measured in the ash at all of the Nanticoke and

Lambton Units.

At Lambton Units 1 and 2 and Units 3 and 4 the percentage of carbon exceeded 10%, similar to fly ash at Nanticoke. This high carbon content coupled with coal chloride greater than 500 ppm (Table 1) likely contributed to the higher-than-average mercury concentration measured in the fly ash. At Lambton 1 and 2, the average fly ash concentration was 0.326 mg/kg and at Lambton 3 and 4 0.274 mg/kg, nearly twice the level measured from the next highest unit.8 CEA Mercury Program Flue Gas Data

Stack sampling was generally conducted by e ither Ontario Hydro method or EPA Method 29 (multimetal sampling method) to quantify mercury emissions from the stacks of several Canadian utilities. Results from these tests in terms of emission rate in grams/hour and, in some cases, speciated mercury concentration are summarized in Table 3. In general, the values presented are an average of triplicate sampling (not necessarily representative of overall annual emissions), and the emission rate represents the estimated mercury emission from each unit. For those facilities that list two units, flue gas is exhausted through a common stack and the emission rate represents the mercury emission from the two units combined.

The stack gas mercury measurements conducted for the CEA Mercury Program typically represent snapshots of emission rates and have not been conducted over long enough periods to fully characterize emissions. However, they do provide useful information when reviewed relative to coal and ash results. The coal and ash data presented in Table 3 differ from the values presented in Tables 1 and 2 in that Table 3 data correspond only with coal and ash data collected during stack test activities. The two factors influencing stack mercury concentrations and emissions are the mercury content in the fuel and subsequent removal via pollution control devices. The mercury concentrations measured from CEA utilities range from 0.32 to 22.05 μg/Rm 3 . NSPI’s Point Aconi (only continuous fluidized-bed combustor tested) measured a stack gas mercury concentration of 0.32 μg/Rm 3 (one of the lowest measured) and, showed a relatively high mercury content in the ash, indicating that significant mercury capture is occurring across the FF. A similarly low stack mercury concentration was measured at OPG’s Lambton Unit 4, indicating mercury capture is occurring across the ESP and/or FGD.

The highest mercury concentrations measured at the stack were at SaskPower’s Poplar River, Boundary Dam, and Shand facilities, where the concentration was greater than 10 μg/Rm 3 from each of the five stacks tested. Speciation data from each of these three stacks show an elemental mercury fraction greater than 70%, consistent with lignite fuels. Coal data from these plants during stack sampling show mercury concentrations typically between 0.05 and 0.10 mg/kg and typically low chloride concentrations, 15 mg/kg. Based on these characteristics, it is not surprising that very little mercury was measured in the ESP ash and emission rates are higher than at other units.

The predominant emission control for Canadian utilities is a cold-side ESP, with the exception of Point Aconi, which has a FF. The other units that are unique among those tested include New Brunswick Power’s Belledune, wh ich operates an ESP and FGD and OPG’s Lambton Unit 4 which has SCR, a C-ESP and F GD. Ash data from Belledune suggest that a significant amount of mercury is not captured by the ESP. However, the stack mercury concentration (1.08–1.2 μg/Rm 3 ) is lower than most of the units tested and suggests that some mercury capture is occurring across the FGD similar to Lambton Unit 4.9 Mercury Policy

The Government of Canada, working closely with provincial and territorial partners, has accepted in principle a draft of the CWS for mercury emissions from coal-fired power plants (www.ccme.ca/initiatives/standards.html). Later this year, the draft will be reviewed by the Air Management Committee, Environmental Planning and Protection Committee, and Deputy Ministers Committee, and a finalized version will be developed. The final CWS is expected to be endorsed by the CCME in the first half of 2006. According to John Mayes, Assistant Director of the Standards Development Branch at the Ontario Ministry of the Environment at Air Quality V, the primary goals for the standard were (3):

• Develop a CWS by 2005

• Explore national capture of 60% to 90% of mercury

• Provide for mercury emission reductions by 2010

• Align with U.S. standards for mercury

The first three of these goals are being met. In accordance with provincial caps provided for under the draft CWS, mercury emissions would be reduced from the current 2695 kg/yr to 1130 kg/yr (58% reduction) by 2010 based on best achievable control technology economically available (BATEA). Therefore, the coal-fired utilities will need to install mercury technologies that can provide 50%–60% control. In addition, as part of the CWS, a review process will be implemented to evaluate requiring much higher levels of control, up to 80% by 2018. For new facilities, the use of best available control t echnologies (BACT) for mercury will be required upon start-up. Based on current estimates, BACT levels would be 85% control for bituminous coals and blends (emission rates of 3 kg/TWh) and 75% control for lignites (15 kg/TWh) and subbituminous fuel (8 kg/TWh).

The reporting and measurement protocols for the CWS have not yet been issued. Based on a recent conversation with Don Rose of Environment Canada, it is expected that these will be issued in early spring of 2006.

Based on the draft, the CWS will require a higher level of mercury control from power plants and in a shorter time frame than the EPA Clean Air Mercury Rule (CAMR). However, by 2018, the CAMR and CWS will be similar. Alt hough trading will be allowed under CAMR, it is not part of the draft CWS.

In March 2005, EPA issued the first-ever mercury regulation titled the CAMR. At Air Quality V, Robert Weyland of EPA said the rationale for the rule was EPA’s desire to allow electric generating utilities as much flexibility as possible and still protect public health (4). As a result, EPA issued the rule under Section 111 rather than Section 112 of the Clean Air Act Amendment (CAAA), thereby providing a cap-and-trade mechanism. The rule is designed to be implemented in two phases. The first phase would cap mercury emissions from coal-fired power plants at 38 tons/year by 2010 (about 48 tons/year is currently being emitted) and the second phase would permanently cap emissions at 15 tons/year by 2018. It is EPA’s position that the first phase will be accomplished as a cobenefit of the February 2005 Clean Air Interstate Rule10Table 2. CEA Mercury Program Ash DataBOTTOM ASH ANALYSIS FLY ASH ANALYSISPower PlantMW Coal TypeBlendRatioBottom Ash:Fly Ash RatioMoisture,%Carbon, %(dry)Mercury1,mg/kg (dry)Mercury,Min/Max.mg/kg*Moisture,%Carbon, %(dry)Mercury,mg/kg (dry)Mercury,Min/Max,mg/kg*ATCO PowerBattle River – 5 375 sub-b.NA 40:60 0.42 0.27 0.006 <0.003/0.011 0.01 0.140.072 0.039/0.126Sheerness – 1 and 2 767 sub-b. NA 40:60 0.46 1.770.006 <0.003/0.031 0.04 0.25 0.124 0.03/0.243EPCOR PowerGenesee – 1 and 2 820 sub-b. NA 40:60 0.122.21 0.003 <0.003/0.005 0.22 0.37 0.088 0.069/0.193Manitoba HydroBrandon GS – 5 105 sub-b. NA 25:75 0.410 0.524 0.029 <0.003/0.102 0.219 0.32 0.166 0.042/0.369New Brunswick PowerBelledune 490 bit. NA 20:80 - - 0.021 0.0010/0.076 0.12 13.49 0.043 0.004/0.156NSPILingan – 1 and 2 300 petc./bit. 21/79 15:85 0.29 - 0.002 <0.003 0.42 - 0.008 0.003/0.107Lingan – 3 and 4 300 petc./bit. 21/79 15:85 0.29 - 0.002 <0.003 0.42 - 0.008 0.003/0.107Point Aconi – 1 165 petc./bit. 75/25 47:530.25 - 0.080 0.074/0.086 0.31 - 0.150 0.069/0.493Point Tupper 150 petc./bit. 18/82 18:82 0.58 - 0.012 0.009/0.015 0.36 - 0.008 <0.003/0.023Trenton – 5 150 petc./bit. 4/96 10:90 0.25 - 0.002 <0.003 0.36 - 0.099 0.004/0.343Trenton – 6 160 petc./bit. 26/74 10:90 0.28 - 0.003 <0.003/0.007 0.31 - 0.029 0.004/0.139OPGAtikokan 215 lig. NA 20:80 0.07 0.17 0.0034 <0.003/0.053 0.04 0.07 0.016 0.003/0.037Lambton – 1 and 2 1000 bit. NA 15:85 - - 0.053 0.020/0.116 10.24 11.19 0.326 0.026/0.530Lambton – 3 and 4 505 each bit. NA 15:85 0.20 10.69 0.119 0.031/0.228 10.43 10.090.274 0.001/0.456Nanticoke – 5, 6, and 7 500 eachsub-b./bit. 70/30 15:850.30 8.89 0.019 0.014/0.022 0.16 10.080.637 0.322/0.847Thunder Bay – 2 and 3 310 lig./sub-b. 80/20 25:75 0.055 0.60 0.063 <0.003/0.342 0.16 0.08 0.002 <0.002/0.003TAUSundance – 5 and 6 760 sub-b. NA 40:60 0.735.24 0.014 0.008/0.020 0.22 1.43 0.141 0.094/0.483SaskPowerBoundary Dam – 1 66 lig. NA 20:80 0.15 2.24 0.013 ND/0.081 0.04 0.47 0.047 0.014/0.079Boundary Dam – 2 66 lig. NA 20:80 0.73 14.46 0.009 ND/0.037 0.07 0.52 0.054 0.017/0.087Boundary Dam – 3 150 lig. NA 20:80 0.19 1.72 0.011 ND/0.060 0.08 0.42 0.044 0.019/0.082Boundary Dam – 4 150 lig. NA 20:80 0.37 13.44 0.072 0.012/0.195 0.05 0.25 0.068 0.041/0.101Boundary Dam – 5 150 lig. NA 20:80 0.13 3.01 0.061 <0.001/0.214 0.12 0.70 0.018 0.002/0.035Boundary Dam – 6 300 lig. NA 20:80 0.32 3.50 0.003 <0.001/0.006 0.03 0.44 0.081 0.042/0.120Poplar River – 1 300 lig NA 20:80 0.17 1.08 0.003 0.001/0.010 0.09 0.14 0.036 <0.002/0.104Poplar River – 2 300 lig. NA 20:80 0.13 1.06 0.003 ND/0.005 0.07 0.19 0.094 0.021/0.221Shand – A Side 305 lig. NA 20:80 0.13 0.93 0.004 ND/0.034 0.09 1.79 0.031 0.004/0.133Shand – B Side 0.06 1.13 0.052 0.012/0.159Note: bit.=bituminous, sub-b.=sub-bituminous, lig.=lignite, petc.=petcoke*Quarterly Data Reports1Where average Hg concentration is below the lower limit of quantification(LoQ), 1⁄2 of the LoQ was reported.11Table 3. CEA Mercury Program Flue Gas DataTotal Hg Emissions Speciation of Mercury EmissionsPower PlantMW/Coal TypeMethodUsedCoalMercury,mg/kg (dry)Bottom AshMercury,mg/kg (dry)Fly AshMercury,mg/kg (dry)Concentration,μg/Rm^3EmissionRate, g/hParticulate,%Oxidized,% Elemental, %ATCO PowerBattle River – 5375 Sub-bM-2910.039 0.004 0.060 4.66 dry 8.05 <1 12 88Sheerness – 1 and 2767 Sub-bM-2910.060 0.002 0.042 3.35 dry 10.33 <1 19 81EPCOR PowerGenesee – 1 and 2820 Sub-b M-29 (2),OH (1)20.043 0.003 0.133 3.25-6.43 7.88-20.66 <1 4 96Manitoba HydroBrandon GS – 5105 Sub-bOH 0.050 <0.003 0.150 3.76-6.38 2.05-2.56 <1 11 89New Brunswick PowerBelledune490 Bit.OH 0.033 0.010 0.059 1.08-1.20 2.03-2.16 2–5 12–22 74–85NSPILingan – 1 and 2300 Petc/BitOH 0.058 <0.003 0.014 4.82 5.82 1 60 40Lingan – 3 and 4300 Petc/BitOH 0.1275 0.002 0.018 - 12.52 - - -Point Aconi – 1165 Petc/BitOH 0.032 0.003 0.149 0.32 0.23 4 66 30Point Tupper150 Petc/BitOH 0.062 0.094 0.016 5.24 3.60 <1 56 44Trenton – 5150 Petc/BitOH 0.093 <0.003 0.069 7.02 4.33 1 61 38Trenton – 6160 Petc/BitOH 0.046 0.004 0.050 3.71 2.28 1 54 46OPGLambton – 43505 Bit.OH 0.095 0.051 0.226 0.36 0.76 1 32 67Nanticoke – 5500 Sub-b/BitOH 0.0643 0.009 0.562 2.73 10.58 1 77 21Nanticoke – 6500 Sub-b/BitOH 0.0703 0.010 0.899 2.50 14.70 <1 48 52Nanticoke – 7500 Sub-b/BitOH 0.0607 0.016 0.721 3.32 13.86 4 86 10TAUSundance – 5 and 6760 Sub-bOH 0.056 0.010 0.146 3.27 10.09 0 5 95SaskPowerBoundary Dam – 1 and 24132 Lig.OH 0.073 0.008 0.080 17.68 (3% O2dry) 11.45 <1 16 84Boundary Dam – 54150 Lig.OH 0.090 - 0.037 19.39 (3% O2dry) 12.13 <1 17 83Boundary Dam – 6150 Lig.OH 0.052 0.002 0.098 14.00 (6% O2dry) 14.30 2 30 73Poplar River – 1300 Lig.OH 0.099 0.006 0.07222.05 (7.7% O2dry) 20.70 0 23 77Shand – 1300 Lig.OH 0.052 0.002 0.056 11.8 (6% O2dry) 14.08 <1 6 93N/A = not applicable1 Results from 1999 OH tests.2 Average of two Method 29 and oneOH test, speciation data from EERC.3 Data from September 10–12, 2003, test.4 Average of two tests (1-EERC, 1-SaskPower); speciation data from EERC.12 (CAIR), which requires that a number of utilities in the eastern states install wet FGD systems

for SO 2 control and selective catalytic reduction (SCR) for NO

x control. Mitchell Baer of DOE added that, although the second phase of the rule will require addition mercury controls, it is expected that a number of mature economical technologies will be available to meet CAMR requirements (5).

As presented in Quarter 7 – Mercury Regulations in the United States: Federal and State, CAMR has been controversial, and 11 states and four environmental groups have filed suit. Of particular concern to the states and organizations is the delisting of mercury from Section 112 of the CAAA which provides for maximum achievable control technology and the decision to regulate mercury under Section 111, providing for a cap-and-trade structure. At the same time, these lawsuits were filed, petitions for reconsideration were sent to the EPA administrator. The petitions requested EPA reconsider both CAMR and the legality of delisting utilities from

Section 112 of the CAAA to Section 111. There were four petitions asking reconsideration of the delisting. One petition was submitted by 14 states: New Jersey, California, Connecticut, Delaware, Illinois, Maine, Massachusetts , New Hampshire, New Mexico, New York, Pennsylvania, Rhode Island, Vermont, and Wisconsin. The second petition was submitted by five environmental groups: The Natural Resources Defense Council, the Clean Air Task Force, the Ohio Environmental Council, the U.S. Public Interest Research Group, and the Natural Resources Council of Maine. The two other petitions received by the EPA were from the

Jamestown Board of Public Utilities and the Integrated Waste Service Association. Two petitions were received to reconsider the met hodology of CAMR in determining caps and NSPS. One petition was received from the same 14 states and the other from five environmental groups and four Indian tribes. As a result, the EPA elected to reconsider on June 24, 2005, by asking for public comment. However, the reconsideration process will not stay the rule.

References

1. www.ceamercuryprogram.ca/EN/Pdf/ CCME%20257-2003%20CRM%20RM%20Report% 20Final%2026%20March%202003.pdf (accessed Dec 2005).

2. www.ceamercuryprogram.ca/EN/I-Plan/IPlan_All.pdf (accessed Dec 2005)

3. Mayes, J. Canada-Wide Standard for Mercury Emissions for Coal-Fired Electric Power Generation Plants. Presented at the Air Quality V: Mercury, Trace Elements, SO 3 , and Particulate Matter Conference, Arlington, VA, Sept 19–21, 2005.

4. Wayland, R.J. Clean Air Mercury Rule (CAMR) . Presented at the Air Quality V: Mercury, Trace Elements, SO 3 , and Particulate Matter Conference, Arlington, VA, Sept 19–21, 2005.

5. Baer, M. Technical and Policy Issues Associat ed with Hg Control Technologies for CAMR and CAIR, DOE Role and Perspective. Presented at the Air Quality V: Mercury, Trace Elements, SO 3 , and Particulate Matter Conference, Arlington, VA, Sept 19–21, 2005.13 SORBENT CONTROL TECHNOLOGI ES FOR MERCURY CONTROL AND

MERCURY CONTROL FIELD DEMONSTRAT IONS (QUARTER 1 AND QUARTER 6 REPORTS)

Field Demonstrations of Carbon Injection

In 1999, the DOE National Energy Technology Laboratory (NETL) issued a request for proposal (RFP) to test mercury control technologies at full scale. The near-term goal of the RFP was to evaluate technologies that could achieve 50%–70% mercury removal at a cost of less than three-quarters of the estimated cost of $50,000–$70,000/lb (CAN$136,000–CAN$191,000/kg) mercury removed. The longer-term goal was to de velop technologies that could provide up to 90% control at a cost of half to three-quart ers of activated carbon injection technology by the year 2010. During 2003 and 2004, NETL issued three more RFPs to evaluate mercury control technologies through its Office of Fossil Ener gy’s Innovation Program and through the Clean Coal Initiative. In 2005, they issued the Phase III RFP to demonstrate control technologies on a longer-term basis that can obtain 90% mercury control. In addition, pilot-scale tests for more novel technologies were encouraged, as well as new techniques for cleaning coal that can remove mercury. It is expected that awards will be made in early spring of 2006.

In September 2005, at Air Quality V: International Conference on Mercury, Trace Elements, SO 3 , and Particulate Matter, Tom Feeley of DOE–NETL presented an update regarding the status of mercury control programs (1). It is clear that significant strides have been made in developing effective mercury control technology over the past several years, particularly for low-rank coals. Based on the status of the Phase II program, Tom Feeley concluded the following:

• Activated carbon/sorbent injection and oxidation systems (i.e., catalysts, chemical additives) are the most promising Hg control technologies.

• The estimated cost of mercury control on a $/lb-removed basis has been significantly

reduced.

• DOE’s current field testing activity is a research and development (R&D) program and, therefore, further long-term field testing is needed to bring technology to commercial

demonstration readiness.

• DOE’s research, development, and dem onstration (RD&D) model projects broad commercial availability of mercury control technologies in the 2012–2015 time frame.

• The fate of mercury in combustion and gasification by-products remains an issue.

Table 4 summarizes 42 large-scale mercury control projects. This information identifies the lead contractor for each project, the demonstr ation site, boiler type and size, fuel type, air pollution control device (APCD) employed, merc ury control technology being evaluated, and project status. The demonstration sites represent utility boilers across the United States and one14Table 4 .Mercury Control Demonstration Projects Funded by the U.S. Department of EnergyLead Contractor Demonstration Site Boiler Type/Size Fuel Type APCD Hg Control Technology StatusUND EERC Leland Olds Station Unit 1Basin Electric Power CooperativeB&W wall-fired220 MWND lignite c-ESP ACI with SEA CompleteADA-ES Inc. Coal Creek Station Unit 1Great River EnergyCE t-fired546 MWND lignite c-ESPWet FGDTOXECON IITM CompleteB&W Endicott StationMichigan South Central Power AgencyB&W Stirling boiler55 MWBituminous c-ESPWet FGDFGD reagent additive CompleteB&W Zimmer StationCinergyB&W Carolinaboiler 1300 MWBituminous c-ESPWet FGDFGD reagent additive CompleteMobotec USA Cape Fear Station Unit 5Progress EnergyCE t-fired154 MWLow-sulfurbituminousc-ESP Sorbent injectionROFATM/ROTAMIXTMCompleteSouthern Company E.C. Gaston Station Unit 3Alabama PowerCE t-fired270 MWLow-sulfurbituminoush-ESPCOHPACTMACI CompleteURS Plant Yates Unit 1Georgia PowerCE t-fired100 MWLow-sulfurbituminousc-ESP ACI CompleteURS Plant Yates Unit 2Georgia PowerCE t-fired100 MWLow-sulfurbituminousc-ESPWet FGDACI CompleteSorbent TechnologiesCorporationSt. Clair Station Unit 1DTE EnergyB&W wall-fired160 MWPRBPRB–bit. blendc-ESP Brominated ACI CompleteSorbent TechnologiesCorporationBuck StationDuke EnergyNA Low-sulfurbituminoush-ESP Brominated ACI CompleteADA-ES Inc. Holcomb StationSunflower Electric Power CorporationB&W CarolinaBoiler 360 MWPRBPRB–W-bit.SDA–FF ACICoal blendingCompleteURS Stanton Station Unit 1Great River EnergyFW wall-fired150 MWPRB c-ESP ACI OngoingURS Stanton Station Unit 10Great River EnergyCE t-fired60 MWND lignite SDA–FF ACI CompleteSaskPower andUND EERCPoplar River Power Station Units 1 and 2SaskPowerNA300 MWPoplar Riverlignitec-ESP ACIPilot-scale slipstreamOngoingADA-ES Inc. Meramec StationAmerenEUNA140 MWPRB c-ESP ACI CompleteUND EERC Stanton Station Unit 1Great River EnergyFW wall-fired150 MWPRB c-ESP ACI OngoingUND EERC Antelope Valley Station Unit 1Basin Electric Power CooperativeCE t-fired440 MWND lignite SDA–FF ACIACI with SEACompleteContinued . . .15Table 4. Mercury Control Demonstration Projects Fundedby the U.S. Department of Energy (continued)Lead Contractor Demonstration Site Boiler Type/Size Fuel Type APCD Hg Control Technology StatusUND EERC Milton R. Young Station Unit 2Minnkota Power CooperativeB&W cyclonefired 450 MWND lignite c-ESPWet FGDMercury oxidationfuel/FG additivesCompleteUND EERC Monticello Station Unit 3Texas Utilities CompanyB&W wall-fired750 MWTexas lignite c-ESPWet FGDMercury oxidationfuel/FG additivesOngoingUND EERC Big Brown StationTexas Utilities CompanyCE t-fired600 MWTexas ligniteLignite–PRBc-ESP ACI OngoingURS Monticello Station Unit 3Texas Utilities CompanyB&W wall-fired750 MWTexas lignite c-ESPWet FGDWet FGD additives OngoingURS Plant Yates Unit 2Georgia PowerCE t-fired100 MWLow-sulfurbituminousc-ESPWet FGDWet FGD additive OngoingURS Conesville StationAmerican Electric PowerNA400 MWBituminous c-ESPWet FGDWet FGD additive 2005ADA-ES Inc. Conesville StationAmerican Electric PowerNA400 MWBituminous c-ESPWet FGDACI 2005ADA-ES Inc. Laramie River Station Unit 3Missouri Basin Power ProjectB&W550 MWPRB SDA–ESP ACI OngoingADA-ES Inc. Monroe Station Unit 4Detroit EdisonB&W785 MWPRB–bit. blend c-ESP ACI OngoingADA-ES Inc. Louisa Station Unit 1MidAmericanB&W650 MWPRB h-ESP Sorbent injection 2006ADA-ES Inc. Independence Station Unit 1EntergyCE840 MWPRB c-ESP TOXECON IITMTBDADA-ES Inc. Gavin StationAmerican Electric PowerB&W1300 MWBituminous c-ESP TOXECON IITMTBDADA-ES Inc. Council Bluff Unit 2MidAmericanNA PRB h-ESP Sorbent injection TBDALSTOM Power, Inc. Dave Johnston StationPacificCorpNA PRB c-ESP ACI with additives CompleteALSTOM Power, Inc. Leland Olds Station Unit 1Basin Electric Power CooperativeB&W440 MWND lignite c-ESP ACI with additives 2006ALSTOM Power, Inc. Portland StationReliant EnergyNA Bituminous c-ESP ACI with additives 2006GE EER John Sevier StationTennessee Valley AuthorityNA Bituminous NA Combined Hg andNOxControl2006Continued . . .16Table 4. Mercury Control Demonstration Projects Fundedby the U.S. Department of Energy (continued)Lead Contractor Demonstration Site Boiler Type/Size Fuel Type APCD Hg Control Technology StatusSouthern Company Daniel Station Unit 1 CE t-fired540 MW60–40 BlendPRB–Bit.c-ESP ACI and brominatedACIOngoingGE EER Lee Station Unit 3Progress EnergyNA Bituminous c-ESP Combined Hg andNOxcontrolOngoingSorbent TechnologiesCorporationLee Station Unit 1Progress EnergyNA Bituminous c-ESP Brominated ACI 2006Sorbent TechnologiesCorporationCrawford Station Unit 7Midwest GenerationNA PRB c-ESP Brominated ACI 2006Sorbent TechnologiesCorporationWill County StationMidwest GenerationNA PRB h-ESP Brominated ACI TBDMobotec USA Whitewater StationRichmond Power and LightNA NA NA Sorbent injectionROFATM/ROTAMIXTMOngoingADA-ES Inc. Presque Isle StationWE EnergyNA NA NA TOXECON IITMOngoingAmended Silicates, LLC Miami Fort Station Unit 6CinergyNA175 MWBituminous c-ESP Amended SilicatesTM2006ACI – activated carbon injection ADA-ES Inc. – ADA Environmental Solutions Inc. B&W – Babcock & Wilcox CompanyCE – Combustion Engineering COHPAC – compact hybrid particulate collector c-ESP – cold-side electrostatic precipitatorFGD – flue gas desulfurization FW – Foster WheelerGE EER – GE Energy and Environmental Researchh-ESP – hot-side electrostatic precipitator NA – not available PRB – Powder River Basin subbituminous coalROFATM– Rotating Opposed-Fire Air ROTAMIXTM– Rotating Mixing SDA–FF – spray dryer absorber–fabric filterSEA – sorbent enhancement additive TBD – to bedetermined t-fired – tangentially firedUND EERC – University of North Dakota URS – URS W-bit. – western bituminous coalEnergy & Environmental Research Center17 in Canada. Boiler types representing the major North American boiler manufacturers are included. Fuel types represented include U.S. northern plains and Gulf Coast lignite, PRB subbituminous coal, high- and low-sulfur bituminous coal, and Canadian lignite. Air pollution control technologies represented include c-ESPs and h-ESPs, various types of wet FGD systems, and SDA–FFs. All of these projects involve the eval uation of some type of additive, reagent, or sorbent for its potential to control Hg emissions in conjunction with existing air pollution control technology or modify Hg speciation in the flue gas to facilitate Hg control.

Most of these tests were previously reported in “CEA Quarter 6 – Mercury Control Field Demonstrations”; therefore, this report will only summarize the key findings and provide reported results for those tests completed recently. Although several projects have been completed, most projects are ongoing, with a significant number scheduled to begin in 2006.

The use of sorbent injection and/or ACI as a means of removing mercury from coal combustion flue gas is widely accepted as the most developed and commercially viable alternative. Many other technologies are being investigated, but the demonstrated performance of activated carbon in pilot- and full-scale tests make it the leading candidate for achieving the goals of the draft CWS for mercury emissions from coal-fired power plants. Although, ACI is considered the most promising and, therefore, the most tested technology option, it should be recognized that not all plant configurations or fu els have been tested to the same degree and additional data are needed to minimize uncertainty and ensure commercial readiness. Clearly, whether ACI is considered a commercially available technology by all groups depends on the level of testing that has been performed thus far and the confidence that the providers (vendors) and buyers (utilities) have in these data. Recent comments by the Institute of Clean Air Companies (ICAC) state that “companies are providing firm price proposals with performance guarantees for every coal and boiler type (2).” However, at the time of this review, there were no guarantees in place at plants in Canada. The President of ADA-ES was recently quoted as saying, “We can take an order for design and install, and a utility could be reducing mercury within six months.” Based on comments that were submitted to EPA prior to the CAMR being announced, utilities and coal suppliers dispute vendors’ ability to make performance guarantees and emphasize that additional testing is needed (3).

There are a number of major producers of powdered activated carbon (PAC) in the United States, Canada, Europe, and China, including the following:

• Norit Americas

• Calgon

• Nucon International

• Luscar, Ltd.

• Barnebey and Sutcliffe Corporation

• RWE Rheinbraun

• Ningxia Huahui18 With a few exceptions, most of the testing has been done with Norit Americas DARCO TM HG (formerly called DARCO TM FGD). However, in practice the carbons have provided similar results and have an average cost of about $0.50/lb.

Results from full-scale tests using ACI at three sites are shown in Figure 1. As was expected, the use of a FF (high air-to-cloth ratio, COHP ACTM) with ACI at the E.C. Gaston Station provided the best mercury removal at the lowest ACI rate, 87%–90% removal at an ACI rate of 1.5 lb/Macf. However, as a result of increased particulate loading to the COHPACTM, the cleaning frequency increased significantly. At Brayton Point Station (ESP alone), burning a similar coal (low-sulfur bituminous), an ACI rate of 20 lb/Macf was needed to obtain 90% mercury removal. At an ACI rate of 1.5 lb/Macf, only about 15% mercury removal was achieved at the Brayton Point Station.

Testing at Pleasant Prairie Station using P RB coal and a c-ESP, resulted in a maximum mercury removal of 66% regardless of the ACI ra te. However, at an ACI rate of 1.5 lb/Macf, mercury removal was ~40%. EERC pilot-scale tests showed relatively low mercury capture when Fort Union lignite was fired with an ESP only. Me rcury removal of only 45% was achieved even at a high ACI rate of 20 lb/Macf (4).

In general, the results shown in Figure 1 are representative of results achieved at many sites. For example a full-scale evaluation of ACI at the Yates plant, was conducted by URS Corporation working with Southern Company (5). The test unit fires an eastern bituminous coal and has a small ESP (SCA of 173 ft 2 /kacfm). Results showed that 60%–70% removal is achievable at 4.5 lb/MMacf, improving to 70%–80% at 6.5 lb/MMacf, with no further improvement at the higher injection rate. In addition to demonstrating mercury removal, another purpose for the test was to determine the effects of ACI on ESP performance. At low loads there

Figure 1. Mercury removal as a function of ACI rate at three sites.19 did appear to be increased arcing across the ESP. However, longer-term tests need to be completed before final conclusions can be made.

Another test recently completed evaluating ACI for a PRB coal was conducted by a team led by ADA-ES (6). Sites tested included Holcomb, Laramie River, Meramec, and Monroe Power Plants. The first three sites fired 100% PRB coal, and the fourth, Monroe, uses a 60–40 blend of PRB–eastern bituminous coal. The emission control configuration was unique for each of the units tested. Holcomb has a SDA–FF, Laramie River a SDA–ESP combination, Meramec only an ESP, and the Monroe plant an SCR followed by an ESP. Mercury removal at Meramec and Laramie River gave results similar to those presented in Figure 1 for Pleasant Prairie. At these plants, the percent mercury removal reaches a maximum and then flattens out, and there is little or no improvement regardless of the amount of carbon added. For Meramec the maximum mercury removal was about 75% at an ACI rate of 5 lb/MMacf; at Laramie River, the maximum was only 45% at the same ACI rate. It is likely that the lower removal at Laramie River was a result of the SDA removing the chloride. However, very different results were obtained at Monroe and Holcomb. At Monroe, which blends eastern bituminous coal with PRB, over 90% mercury removal was achieved at an ACI rate of 5 lb/MMacf, with similar results at Holcomb, 90% removal of mercury at an ACI rate of 6 lb/MMacf.

Field Demonstrations Using Chemically Treated Carbons

It has been determined, based on bench- and pilot-scale tests, that a limiting factor for western fuels is the relatively low level of chlorides in the coal compared to eastern bituminous coals. Therefore, one method to improve ACI performance is to treat the carbon with a halogen, chlorine, bromine, or iodine. The primary focus for many of the Phase II field demonstration projects was to use these halogenated carbons to achieve higher levels of mercury control. For example, Sorbent Technologies has developed brominated powered activated carbons (B-PACs) that have proven very effective at removing merc ury at a variety of power plants (7). Some plants have achieved >90% mercury removal at a cost that is <50% of DOE’s baseline estimate. Based on this and other work, it appears that halogenated carbons can improve mercury capture for low-chloride coals but provide less benefit for eastern fuels.

In similar testing led by URS Corporation, a Darco-Hg LH TM carbon (a brominated carbon) was tested at Great River Energy’s Stanton Sta tion Units 1 and 10 (8). Unit 10 is small (60 MW) boiler burning a North Dakota lignite with a SDA–FF combination, and Unit 1 is a larger boiler (150 MW) burning a PRB coal and operating an ESP. For Unit 1, the target of 60% mercury removal was achieved (ranged from 45% to 80%) at an average injection rate of only 0.7 lb/MMacf. Tests are just getting under way on Unit 1.

In addition to using halogenated carbon, additives can be used with ACI to improve mercury removal for low-rank fuels. The EERC recently completed longer-term testing at Antelope Valley Station (AVS) using a combina tion of SEA with ACI (9). AVS fires North Dakota lignite and has a SDA–FF. Month long test results have shown that with only 0.81 lb/MMacf ACI and 0.033 lb/MMacf of SEA, >90% mercury removal was achieved. This is compared to a near-zero baseline capture and 43% capture with ACI only.20 There has also been research ongoing to utilize other sorbent materials or substrates that are not carbon-based such as amended silicates. However, these materials have yet to be

demonstrated at the full-scale level.

Economics of ACI

Based on an economic study done by Hoffman and Ratafia-Brown for DOE (10), it was estimated that the capital cost for ACI equipment for a 500-MW plant would be US$3–US$4/KW. For smaller systems, the cost can be as high as US$8/KW. Typically capital costs for an ACI system include the following:

• Equipment transportation costs

• Equipment installation costs including concrete pads and injection ports

• Activated carbon storage silo

• A feeder skid that includes blowers, variable screw feeders, and control system

• Injection lances including piping and distribution manifolds

The following are variable operating and maintenance (O&M) costs associated with ACI:

• Sorbent

• Activated carbon disposal

• Power

• Operating labor

• ACI equipment maintenance

• Water (for spraying additives if used)

• Cost of money (inflation and interest)

In addition to these items another potential cost would be the loss of revenue from selling fly ash and the resultant increased disposal costs. An alternative to lost ash revenue is installation of a FF. Costs for this option include capital improvements, pressure drop (increased power requirements), general maintenance of the baghouse, and bag replacement. Table 5 presents the total O&M cost for each plant in Canada based on the carbon usage for each plant (CCME). The

cost of the sorbent is 90%–95% of the total O&M cost.

References

1. Feeley, T.J.; Brickett, L.A.; O’Palko, B.A.; Murphy, J.T.; Jones, A.P. An Update on the U.S. Department of Energy’s Phase II Mercury C ontrol Technology Field Testing Program. In21 Table 5. Additional O&M Costs for Canadian Power Plants as a Result of Adding ACI (11)

Power Station Net Capacity,

MW Units Total O&M 1
For All Units, million $/yr (US)

Alberta

Battle River 675 3 8.95–12.41

Sheerness 766 2 6.44–8.00

Genesee 1182 3 6.46–12.61
Keephills 766 2 4.44–8.66

Sundance 2020 6 11.50–22.40

Manitoba

Brandon 95 1 0.30–0.59

New Brunswick

Belldune 450 1 0 2

Nova Scotia
Lingan 600 4 1.32–4.92

Point Aconi 165 1 0 3

Point Tupper 150 1 0.60–1.16

Trenton 310 2 1.23–2.37

Saskatchewan
Boundary Dam 814 6 5.11–19.86
Poplar River 562 2 3.38–13.08

Shand 279 1 1.71–6.60

1 O&M costs are based on a report to DOE (11).

2 Belldune is already achieving 70% mercury control (w-FGD).

3 Point Aconi is already achieving 60%–90% mercury control (CFB).

2. Proceedings of the Air Quality V: Mercury, Trace Elements, SO 3 , and Particulate Matter Conference , Arlington, VA, Sept 19–21, 2005.

3. Clean Air Compliance. North American Emissions Regulation and Markets. Argues Media

2005

, 17 (01).

4. Proposed Rules. Fed. Regist. Proposed Rules, 2004

, 69 (230) www.epa.gov/mercury/control_emissions/noda.htm.

5. Holmes, M.J.; Pavlish, J.H.; Benson, S.A.; Zhuang, Y. Developing Mercury Control Options for Utilities Firing Western Fuels. In Proceedings of the 19th Western Fuels Symposium ; Billings, MT, Oct 2004.22 6. Dombrowski, K.; Richardson, C.; Chapman, D.; Chang, R.; Monroe, L.; Berry, M.; Glessman, S.; Campbell, T.; McBee, K. Full-Scale Evaluation of Activated Carbon Injection. In Proceedings of the Air Quality V: Mercury, Trace Elements, SO 3 , and Particulate Matter Conference ; Arlington, VA, Sept 19–21, 2005.

7. Sjostrom, S.; Starns, T.; Wilson, C.; Amrhein, J.; Durham, M.; Bustard, J.; O’Palko, A.; Chang, R. Full-Scale Evaluations of Mercury C ontrol for Units Firing Powder Basin Coals.

In Proceedings of the Air Quality V: Mercury, Trace Elements, SO 3 , and Particulate Matter Conference ; Arlington, VA, Sept 19–21, 2005.

8. Nelson, S.; Landreth, R.; Liu, X.; Tang, Z.; Miller, J.; Weaver, D.; McMurray, R.; Potter, S.; Corey, Q.; McCoy, M.; Rogers, W.; Slye, R.; Ley, T.; Brickett, L.; Chang, R. Power-Plant Mercury Control Results with Brominated PAC and ESPs. In Proceedings of the Air Quality V: Mercury, Trace Elements, SO 3 , and Particulate Matter Conference ; Arlington, VA, Sept 19–21, 2005.

9. Dombrowski, K.; Richardson, C.; Frenzel, D.; Ley, T.; Ebner, T.; Chang, R.; Strohfus, M.; Smokey, S.; Brickett, L. Full-Scale Activated Carbon Injection for Mercury Control in Flue Gas Derived from North Dakota Lignite and PRB Coal. In Proceedings of the Air Quality V: Mercury, Trace Elements, SO 3 , and Particulate Matter Conference ; Arlington, VA, Sept 19–21, 2005.

10. Holmes, M.J.; Wocken, C.A.; Pavlish, J.H.; Hill Brandt, K.L.; Ericksen, B.; Brickett, L. Field Testing of Mercury Control for Lignite-Fired Systems with Activated Carbon and Sorbent Enhancement Additives: Field Test Results from Antelope Valley Station. In Proceedings of the Air Quality V: Mercury, Trace Elements, SO 3 , and Particulate Matter Conference ; Arlington, VA, Sept 19–21, 2005.

11. Hoffman, J.; Ratafia-Brown, J. Preliminary Cost Estimate of Activated Carbon Injection for Controlling Mercury Emissions from an Unscrubbed 500-MW Coal-Fired Power Plant ; Science Applications International Corporati on Final Report for U.S. Department of Energy National Energy Technology Laboratory, Nov 2003.

12. Pavlish, J.H.; Laudal, D.L.; Holmes, M.J.; Hamre, L.L.; Musich, M.A.; Pavlish, B.M.; Weber, G.F.; Hajicek, D.R. Technical Review of Mercury Technology Options for Canadian Utilities – A Report to the Canadian Council of Ministers of the Environment ; 2005-EERC03-07; March 2005.23 MERCURY MEASUREMENT (QUARTER 2 REPORT)

With mercury regulations in place and full-scale, long-term demonstration of control technologies being conducted, measurement of merc ury in combustion flue gas is of critical importance to demonstrate compliance and to allow evaluation of mercury control technologies. However, collecting a representative flue gas sample for mercury analysis presents many challenges owing to complex flue gas chemistry, high temperatures, mercury reactivity, and particulate loading. Given these challenges, many methods and instruments are available under varying degrees of development.

The most common approach for measuring mercury emissions from anthropogenic point sources consists of sampling train methods. Several common impinger-based methods include EPA Method 29, and the Ontario Hydro method (ASTM D6784-02). Each of these methods relies upon an isokinetic nozzle and filter to collect a flue gas sample, which is transported through a variety of liquid and solid sorbents to separate and preconcentrate gaseous mercury species. Quantification of the collected mercury species is then conducted using cold-vapor atomic absorption spectroscopy (CVAAS), cold-vapor atomic fluorescence spectroscopy (CVAFS), or energy-dispersive x-ray fluorescence (EDXRF).

A similar sample collection approach can also be applied to capture mercury species on a solid sampling medium through adsorption, amalgamation, diffusion, or ion exchange. These methods offer advantages in easier handling and greater stability; however, they are limited to time-averaging applications. Examples of these methods are the FAMS, QuickCEMs, and EON

methods.

Real- or near-real-time data collection can only be obtained using continuous mercurymonitors (CMMs). A large variety of CMMs are available utilizing a variety of flue gasconditioning approaches; however, all commercially available instruments measure elemental mercury and use either chemical or thermal treatment to convert mercury. As they are currently configured, CMMs possess several challenges to long-term, low-maintenance operation, the most significant of which include sample coll ection and flue gas conditioning. Mercury species reactivity and particulate loading make transporting a representative gas sample to the instrument a challenge and require heated sample lines and particulate removal techniques which prevent the buildup of a filter cake. Flue gas conditioning is an area where the greatest development is occurring. Wet-chemistry methods have typically been used to convert mercury to the elemental form that the analyzer can detect. These solutions are corrosive or caustic chemicals, and challenges associated with their use are considered the limiting factor in CMM reliability. Dry conversion units are now being marketed and are being used in field demonstrations. These systems focus on high-temperature catalysts and thermal reduction to convert oxidized mercury to the elemental form for analysis. It is anticipated that developments in this area will be the critical factor in ensuring real-time mercury measurements can be conducted reliably under steady-state operation.24 The new regulations for mercury emissions from U.S. coal-fired boilers will require some form of continuous monitoring. EPA has announced that two measurement methods will be accepted: the sorbent trap methods as prescribed by 40 CFR, Part 75, Appendix K (Appendix K), and CMMs. Initially a number of utilities will opt for the sorbent trap methods; however, this could change as more robust CMMs become available. For both of these methods, EPA has established performance specifications (PS 12A), which relate to the setup, certification, and quality assurance/quality control (QA/QC) for each method. A summary of these specifications is provided; details can be found at www.epa.gov/mercuryrule.

Since May 2005, when the Mercury Information Clearinghouse second quarterly report was last updated, there have been a number of developments in mercury measurement, including the following:

• Additional experience gained with 40 CFR, Part 75, Appendix K Specifications

• Establishment of performance specifications and clarification of QA/QC requirements including relative accuracy test

• Additional experience gained with next-generation CMMs

• Possibility of an instrument-based reference method for mercury measurement

Additional Experience with 40 CFR, Part 75, Appendix K Specifications

To date, mercury emissions at over 85 stacks have been characterized using the twosection traps or the QuickCEM method (Dene). However, the QuickCEM as initially configured used only two sections, and Appendix K now requires the use of a third trap section designated for QA/QC purposes. The first two sections are still used to trap the gas-phase mercury and ensure there is no breakthrough. The third section is spiked with a known quantity of elemental mercury, and a correction factor based on the recovery is applied to the concentrations measured in the first two sections. Results presented at a recent Electric Power Research Institute (EPRI)- sponsored mercury measurement workshop indicated there are problems with the consistency of the spiking and recovery of the third section. Spike recoveries as low as 30% have been observed. The existing spiking method needs to be refined or a new method developed in order to ensure reliable and consistent third sections that can be used for QA/QC. The addition of the third section has also increased the cost of the dry sorbent method. Traps with a spiked third section can cost from $590 to $710 per trap to purchase and analyze. This cost does not include the cost of equipment or labor. It is expected that during the next 1–2 years, costs will be reduced considerably as more cost-effective spiking and analytical methods are developed.

QA/QC Requirements for Mercury Measurement RATAs

In the draft of PS 12A the paired reference method samples were required to be within 10% of the relative standard deviation of the results. That requirement was changed in the final version. The paired samples are now required to meet the following relative difference (RD)

criteria:25 RD C C

(C C ) 100%

RD 10% for Hg concentration > 1 g / m

or
RD concentration 1 g / m a b

a b

3

3 = −

+ ×

≤

≤ ≤ μ

μ 20% for Hg

Additional Experience Gained with Nex t-Generation Continuous Mercury Monitors

In addition to the use of CMMs during large-scale mercury control demonstration projects, EPA (Segall) has been evaluating several commercially available CMMs at two tests sites (Sites 1 and 2), which both burn eastern bituminous coals. Instruments that have been evaluated to dateinclude the Tekran Model 3300, Thermo Electron Mercury Freedom System, Horiba/NIC DM6B, Forney/Genesis Model 6500, Durag HM-1400, and the Opsis HG200. In addition to these instruments, Appendix K sorbent traps were also tested. All of the instruments at some point have passed the initial certification requirements of PS-12A, but to date, only two instruments have passed at least one of the RATAs: the Thermo Electron (passed at the first site) and Tekran systems (passed at both sites). EPA is planning additional RATAs in 2006. The Thermo Electron instrument will be commercially available in late 2005 or early 2006.

Now that EPA has issued performance specification for mercury monitors, vendors have a much better idea of what will be required As a result, mercury measurement technology is moving forward rapidly, and reliable, rugged systems should be available well before the January 1, 2009, deadline. Mercury control demonstration projects are now using CMMs for long-term monitoring of mercury concentrations at stacks and other locations within the power plant with good success. These tests (3 to 6 months in duration) should provide additional data as to the overall reliability of CMMs.

An Instrument-Based Reference Method for Mercury Measurement

A major concern for both certifying a CMM based on PS 12A and ongoing QA/QC requirement under 40 CFR, Part 75 is the requirement that all RATAs are to be conducted using the Ontario Hydro method. Obtaining nine valid paired sample trains is a challenge and will be very expensive for utilities. Therefore, EPA is trying to develop criteria for an instrument-based reference method. While a draft procedure may be available soon, there will be some major

obstacles to overcome before an instrument-based reference method can be used. One of the main obstacles is the ability to dynamically spike both elemental (Hg 0 ) and oxidized mercury (Hg 2+ ) to the tip of the sampling probe. Dynamic spiking requires the addition of a small amount of spike gas into the sample gas matrix. This is not required in the new regulations for the CMMs. All of the major CMM manufacturers are working on developing some type of mercury generation and delivery system. In order for the results from these systems to be accepted, they will need to be National Institute of Standards and Technology (NIST)-traceable. EPA has asked NIST to help provide traceability for gas standards. NIST is currently working on certification of Hg 0 gas cylinders and mercury gas generators, such as those provided by the PS Analytical and Tekran systems, for delivering Hg 0 . They have determined that the expanded uncertainty for the26 gas cylinders is approximately 6%, which is an order of magnitude higher than they usually get with other types of gas cylinders and not acceptable as a standard. A new equation for the mercury vapor pressure curves is also being proposed by NIST. Currently NIST, PS Analytical, and Tekran all use slightly different equations fo r Hg vapor pressure. NIST also plans to look at the long-term stability of the gas cylinders and mercury generators.27 ADVANCED AND DEVELOPMENTAL MERCURY CONTROL TECHNOLOGIES (QUARTER 3 REPORT)

A variety of approaches for mercury control are under development, ranging from combustion modification to multipollutant technol ogies. Many of these unique technologies have passed the bench- and pilot-scale developmental phases and are now being tested at full scale. Many of these technologies were discussed in Quarter 3 and updated in Quarter 6 and include:

• Pretreatment of coal to remove mercury.

• Combustion modification and in situ generation of sorbents.

• Non-carbon-based sorbent and amended silicates.

• Stationary mercury traps positioned in the flue gas stream.

• EnviroScrub Pahlman Process.

• Combined oxidation of NO

x and mercury.

• Mercury control with the Advanced HybridTM Filter.

Since the amount of mercury in coal is very small (typically about 0.1 μg/g), the total amount of mercury input (and potential emissions) for a 500-MW plant in a year is only about 300 lb. This suggests that there is potential for generating a minimum amount of waste material if the mercury can be effectively captured and concentrated. On the other hand, if the captured mercury is highly dispersed in waste material or by-product, the mercury must be proven to be in a stable form so that there is little possibility of reemission into the atmosphere. This will be a significant factor in the development of new technologies for long-term mercury control.

Pretreatment of the Coal to Remove Mercury

Removal of mercury from the fuel prior to combustion is a mercury control approach that has been considered for many years. Standard coal-washing methods for bituminous fuels to remove pyrites and other mineral matter result in the removal of some of the mercury; however, not to the extent that would be needed to meet future control requirements. Coal washing for ash reduction has proven to be effective primarily for bituminous fuels with large mineral grains. With subbituminous and lignite fuels, conventional coal washing is not effective because of the way the inorganic material is distributed within the coal. However, for subbituminous coals, deep cleaning or pretreatment of the coal, such as with the KFx K-Fuel process, has the potential to remove a significant fraction of the mercury.

A large-scale plant that can produce 750,000 tons per year of K-Fuel is nearing completion. The actual level of Hg reduction in the final fuel product as well as the fate of the removed mercury within the process will be demonstrated when the process becomes fully operational. PRB coals already account for about one-third of U.S. production and represent most of the growth in U.S. production in the last 10 years. Whether a significant portion of that production could eventually be upgraded as K-Fuel or similar products is primarily an economic one and highly dependent on tighter regulations. The current upward trend in world oil prices

and focus on CO 2 emission reduction would both appear to make K-Fuel more attractive in the28 marketplace. The success of the first full-scale pl ant as well as the strength of the market will determine how fast new capacity is developed to meet demand.

Another example of fuel-upgrading is th e Great River Energy project, funded by DOE, which focuses on drying of high-moisture North Dakota lignite. The process does not claim to remove mercury from the lignite but upgrades the fuel with waste heat, resulting in overall plant efficiency improvement, with some subsequent reduction in mercury emissions. However, even with mild thermal processing of a raw fuel, there is potential for removing some of the mercury along with the moisture by increasing the drying temperature.

In the recent Phase III RFP issues by DOE, one of the topics was new coal-cleaning technologies that would enhance mercury removal for lower-rank fuels.

Combustion Modification and in Situ Generation of Sorbents

An attractive approach to mercury control is to enhance the capture of mercury by modification of the combustion process to produce fly ash or unburned carbon that results in better mercury retention. The thought is that either increased carbon in the ash or generation ofcarbon in the ash with the appropriate characteristics will enhance mercury capture. Since lowNO

x burner (LNB) technology is already known to produce more carbon in the ash, a logical extension of LNB approaches is to specifically modify the process for enhanced mercury control, such as is being investigated in a DOE-funded project by General Electric Energy and Environmental Research Corporation (GE EER) and Lehigh University. Another interesting approach is extracting a portion of the coal from the combustion zone and then quenching it prior to complete combustion to produce a material with good mercury sorption characteristics. This approach is know as the Thief process and is being developed at DOE NETL. Another somewhat similar approach is detailed in two EPRI patents that describe a method for in situ activation of carbon-based sorbents by injecting carbonaceous material at the appropriate location in a boiler.

The largest single advantage for all three control technologies is that mercury capture could potentially be achieved with the coal. The GE EER process is the furthest along and is being tested at full scale. Of the three processes, this is also the simplest and would appear to be most likely implemented in the near future. One of the main concerns is that the process depends on incomplete combustion and the presence of significant unburned carbon in the ash. This makes fly ash utilization and disposal more challenging.

The Thief process appears to offer more flexibility in achieving a much higher-capacity carbon but with additional complexity. Since the Thief process can include injection downstream of a primary particulate control device, it also offers an opportunity for separating the fly ash from the spent carbon. However, similar techniques can be implemented with many sorbent injection technologies.

The EPRI process offers flexibility with the raw feed materials which may offer an opportunity to generate a very highly reactive, high-capacity sorbent. Since the generated sorbent material does not have to be collected and reinjected, the process may offer an opportunity to generate a very fine particle-size material. If so, in-flight capture would be29 enhanced, making it an attractive application for ESP-controlled units. This process, however, has not been substantially tested, so near-term development is unlikely.

Non-Carbon-Based Sorbent, Amended SilicatesTM

ADA Technologies, Inc., has been developing a non-carbon-based mercury sorbent for several years. The Amended Silicates material will be tested in 2006 under the DOE-funded large-scale mercury demonstration program. Am ended Silicates, LLC (a joint venture of ADA Technologies, Inc., and CH2M Hill), Littleton, Colo rado, will test the material at Cinergy’s 175- MW Miami Fort Unit 6 that burns bituminous coal. The research team also includes the EERC, Western Kentucky University, and Boral Materials Technologies. Current plans are for this testing to begin in February–March 2006.

A sorbent that is non-carbon-based is highly attractive because of the potential for ash utilization without concern over additional carbon in the ash. Based on material properties and test results to date, no impact of the material on fly ash utilization is expected.

Critical developmental questions concern the level of control that can be demonstrated compared to existing and new activated carbons and the stability of the mercury in the ash. The ability to manufacture large amounts of the material at a reasonable cost also needs to be

demonstrated.

The concept has moved beyond the bench-scale level and has been tested at the pilot level at a coal-fired power station. The current DOE-funded project will take the evaluation to the fullscale demonstration level.

Stationary Mercury Traps Positioned in the Flue Gas Stream

MerCAPTM

The general MerCAP (Mercury Control via Adsorption Process) concept is to place fixed structures into a flue gas stream to adsorb mercury and then periodically regenerate them and recover the captured mercury. While a variety of regenerable sorbent materials could be used, most of the development work has focused on the use of gold-coated substrates in the form of parallel plates spaced about 0.5 to 1 in. apart. Previous work has shown that the level of control is impaired in an unscrubbed flue gas environment. Subsequently, current development efforts seek to achieve high levels of mercury removal in scrubbed flue gases, either downstream from a spray dryer scrubber or a wet scrubber.

DOE NETL is currently funding a demonstration of MerCAP, conducted by URS Group. Testing has already been completed at Great Ri ver Energy’s Stanton Station, which burns North Dakota lignite, where MerCAP sorbent structures treated 6 MW e equivalence of flue gas when retrofitted into a single compartment in the ou tlet plenum of the Unit 10 baghouse. Additional testing is planned this year at Southern Company Services’ Plant Yates, which burns eastern

bituminous coal.30 The MerCAP process by itself has the potential to achieve >90% mercury removal when installed downstream of a scrubber. However, any upstream removal of oxidized mercury by the scrubber makes the total mercury removal of >90% even more likely. With regeneration, the mercury can be isolated for disposal, and since the mercury can be concentrated, permanent sequestering of the captured mercury is possible with a minimum volume of material.

Since the concept depends on the amalgamation of mercury with gold, a key concern is the absorption ability of the gold as well as the regeneration ability and lifespan of the material. A very critical developmental question is how sensitive the material is to small concentrations of HCl or other gases that affect the absorption of mercury. In longer-term testing up to 5000 hr, actual mercury removal levels have only been in the range of 30%–40%. However, at the recent AQV Conference, URS reported that new regene ration technologies are being employed that

enhance overall removal.

W.L. Gore & Associates, Inc.,-Promoted Felt Filter Bag Inserts

W.L. Gore & Associates, Inc., has developed an innovative technology for control of mercury emissions in flue gas streams. The configuration involves a mercury control filter placed inside the existing particulate control filter bag. This concept is similar to the MerCAP technology in that both attempt to achieve mercury capture by placing an adsorbent material in a convenient location within the system and then periodically (e.g., every 6 months) removing the components for regeneration and/or mercury concentration.

The Gore mercury filter system has been tested at the small pilot-scale level both at EPA facilities and at the EERC. Operationally, the mercury filter elements did not appear to impair the pulse cleaning of the bags. Results showed that, initially, nearly 100% mercury removal could be achieved. However, for the materials tested, early breakthrough occurred under some conditions. The process appears to have potential, but currently there are no known testing programs outside of Gore to further develop this technology.

EnviroScrub Pahlman Process

A multipollutant control technology that is tr uly unique is being developed by EnviroScrub Technologies Corporation. In 2000, EnviroSc rub acquired the dry PahlmanTM scrubbing technology, which can simultaneously remove SO x, NO

x , and Hg. The Pahlman process uses a sorbent composed of oxides of manganese. These specialized sorbents have been generically named PahlmaniteTM sorbent in honor of the late Dr. John E. (Jack) Pahlman who led the early research and development work on the process.

As presented, the technology is placed downstream of a particulate control device so that the captured mercury will not be mixed with the fly ash. This facilitates fly ash disposal as well as fly ash utilization as a by-product.

The concept has moved beyond the bench-scale level and has been tested with a 1000-acfm trailer-mounted slipstream device at a number of coal-fired power stations. However, only the collection step has been demonstrated. The fairly complex regeneration and recycling31 steps have not been tested. Much longer-term and larger-scale testing needs to be completed to address all aspects of the process, but little additional development work has been done within the last year.

Combined Oxidation of NO

x and Mercury

Two processes that oxidize mercury along with NO

x for capture in an ammonia-based wet scrubber are unique. Both the BOC LoTOxTM and ECOTM/Powerspan are NO

x control approaches whereby the NO

x is oxidized to a soluble form to allow capture in a wet scrubber. Even though the oxidation approaches for the two processes are different, both of these processes claim that elemental mercury is also oxidized to HgO and subsequently captured in the wet scrubber along with SO 2 and NO

x . Both of the processes are coupled with an ammoniabased wet scrubber.

LoTOxTM

The BOC LoTOx system is based on the patented Low-Temperature Oxidation (LTO)

Process for Removal of NO

x Emissions, exclusively licensed to BOC Gases by Cannon Technology. Marsulex Inc. and the BOC Group have signed a joint marketing agreement that will enable each company to offer electric utilities an integrated multipollutant control solution that provides maximum compliance for emissions of sulfur dioxide, sulfur trioxide, nitrous oxides, mercury, and other heavy metals in conjunction with ammonia-based wet scrubbing. The LoTOx system is a NO

x removal system that injects ozone into the flue gas stream to oxidize

insoluble NO

x to soluble oxidized compounds. The mercury removal is achieved by oxidizing elemental mercury with ozone to produce soluble HgO, which is captured in a downstream wet scrubber. The current status of the LoTOx process for mercury control is unknown.

ECO/Powerspan

Powerspan Corporation is the primary researcher and proprietary owner of the ECO process. However, Powerspan has entered into an alliance with Wheelabrator Air Pollution Control, Inc., to commercialize the system. Powerspan and First Energy jointly funded the latest pilot plant. In addition, DOE awarded a grant to Powerspan to optimize the mercury removal capability of the technology on a 50-MW demonstration facility at the R.E. Burger Plant.

In the ECO process, flue gas exiting the ESP or FF is routed to the ECO reactor where it is exposed to a high-voltage discharge, which generates high-energy electrons. These high-energy electrons initiate chemical reactions that lead to the formation of oxygen and hydroxyl radicals. These radicals then oxidize the pollutants in the flue gas, leading to the formation of particulate matter and aerosol mist. These components are removed downstream in an ammonium salt wet scrubber and wet ESP forming the ammonium sulfate and ammonium nitrate by-products. Approximately 90% of the NO in the flue gas is oxidized to NO 2 and is removed in the scrubber (the other 10% remains unoxidized). Less than 10% of the SO 2 in the gas is oxidized to form

SO 3 , which eventually forms sulfuric acid (H 2 SO 4 ). Elemental mercury vapor is oxidized to form mercuric oxide (HgO), which is removed by the wet scrubber/wet ESP.32 Extensive mercury removal results have been reported in the last year from the pilot unit tests at the Burger Plant. Results showed that over 90% mercury removal was achieved, but most of the inlet mercury was already oxidized. Additional testing in which supplemental elemental mercury was injected upstream showed that up to 75% of the elemental mercury was converted to oxidized mercury across the reactor, and the total mercury removal for the system was still over 80%. Testing to evaluate removal of the collected mercury from the scrubber liquor showed that well over 90% of the mercury was removed so that in many cased the mercury level in the scrubber liquid was below detection limits.

FirstEnergy recently announced plans to install an ECO system on the 215-MW Unit 4 boiler at its Bay Shore Plant in Ohio.

Mercury Control with the Advanced Hybrid TM Filter

Since 1995, DOE has supported development of a new concept in particulate control, called the advanced hybrid particulate collector marketed as the Advanced Hybrid filter. The Advanced Hybrid filter combines the best features of ESPs and baghouses to provide ultrahigh collection efficiency, overcoming the problem of excessive fine-particle emissions with conventional ESPs. Additionally, it solves the problem of reentrainment and re-collection of dust in conventional baghouses. The Advanced Hybrid filter also appears to have unique advantages for mercury control over baghouses or ESPs as an excellent gas–solid contactor. Since most of the sorbent material will collect on the perforated plates, there will be minimal effect on the pressure drop across the filter bags. In addition, better gas–solid contact is achieved than in conventional ESPs because the distance that gas must cross streamlines to reach sorbent particles is much smaller than in ESPs. Mercury control with commercially available sorbents was

demonstrated with a 2.5-MW Advanced Hybrid filter at the Big Stone Power Plant, which burns

subbituminous coal from several different PRB mines.

Over 90% mercury control was demonstrated at low carbon addition rates upstream of the Advanced Hybrid filter with commercially available NORIT FGD activated carbon. However, the level of control was dependent on other flue gas components. One of the very interesting findings was the discovery that when the plant cofired a small amount of tire-derived fuel, the level of mercury captured in the fly ash, the fraction of oxidized mercury in the inlet flue gas, and the level of total mercury removal with activated carbon all were significantly increased, likely due to the increased chlorine content from tire-derived fuel. Another significant result was that the injection of activated carbon for mercury control had no effect on bag-cleaning interval or pressure drop. The perforated plate geometry of the Advanced Hybrid filter allows sufficient gas–solid contact to achieve over 90% mercury removal at low carbon addition rates, even though most of the carbon is collected on the perforated plates.

The concept for mercury control has moved beyond the bench scale and has been tested at the 2.5-MW pilot level at a coal-fired power station. However, there are currently no plans for a full-scale demonstration to evaluate mercury control effectiveness with the Advanced Hybrid

filter.33 RERELEASE OF MERCURY FROM COAL COMBUSTION BY-PRODUCTS (QUARTER 4 REPORT)

At the time the CEA Quarter 4 report was written, only a limited amount of empirical data were available on mercury stability in coal combustion by-products (CCBs). Early work on rerelease of mercury from CCBs focused on developing and adapting methods to determine the potential for mercury to be rereleased from CCBs. Since that time, additional data have become available including results of field testing from mercury in ground and surface water at CCB disposal sites and vapor-phase mercury measurements at disposal and utilization sites.

In August 2005, DOE NETL selected Frontier Geosciences (Seattle, Washington) to conduct research on by-products generated from DOE’s mercury control program. As the majority of mercury control technologies result in additional concentrations of mercury being deposited in the fly ash or FGD material, Frontier will analyze multiple by-product samples for mercury and other elements from 31 different fi eld sites. The tests will include volatilization, leaching (both abiotic and biotic), total element concentrations, and limited halide analyses (1). It is anticipated that some of the materials to be evaluated under the new DOE NETL program will include those with combinations of activated carbon and mercury capture-enhancing agents. Additional work is also expected on FGD materials under this program.

The most significant concern associated with CCB management and mercury emission controls continues to be the use of ACI to achieve mercury capture in the particulate control device. The result of ACI is an elevated carbon and mercury content in fly ash which has implications on ash reuse and raises concerns related to the stability of mercury in subsequent uses of the fly ash. The major utilization application for coal combustion fly ash is concrete and concrete products. The impact of ACI on ash suitability for the concrete industry has been apparent and reported by Starns (2) for an ACI demonstration at We Energies’ Pleasant Prairie Power Plant. Additional questions have been raised more recently about how additives, added to ACI systems to improve mercury capture, will impact not only fly ash, but other CCBs as well. While these additives are designed to enhance the removal of mercury from emissions, the fate of these chemical additives remains unclear and will also be investigated as mercury emission control testing continues.

The other CCB being evaluated relative to mercury capture and rerelease is FGD materials. FGD effluents had only been evaluated for mercury rerelease on a very cursory level at the time of the original report submission. Since that time, additional work has been done to determine total concentrations of mercury in various FGD materials as well as on the rerelease of mercury

from FGD materials under different environmental conditions.

Stability of Mercury on CCBs

Total mercury concentrations for CCBs are of interest because these data are valuable in developing mercury balances across emission control systems. Additional data have been reported by several groups primarily on those CCBs most directly impacted by potential mercury emission controls. Table 6 provides a summary of data on fly ash and FGD materials collected34 Table 6. Total Mercury in CCBs and Mercury-Leaching Results Reported by Various Groups

Information Source CCB Type Number of Samples in Sample Set Range of Total Hg (μg/g) Reported Leaching Method Number of Samples in Sample Set Range of Mercury Leachate Concentrations Hg, μg/L EERC (3) Fly ash without Hg

control 40 <0.01–2.03 Batch

DI H 2 O 72 <0.01–0.32

EERC (3) Fly ash with Hg control 28 0.15–120 Batch

DI H 2 O 43 <0.01–0.07

EERC (3) FGD material without Hg

control 10 <0.01–0.22 Batch

DI H 2 O 18 <0.01–0.40

EERC (3) FGD with Hg control 1 0.33

Schroeder and Kairies (4) FGD gypsum 2 0.140–0.142

Schroeder and Kairies (4) FGD sludge – top layer (from nonoxidized wet scrubber) 2 2.90–13.0

Schroeder and Kairies (4) FGD sludge – bottom layer (from nonoxidized wet scrubber) 2 0.072–0.70

Kim and Schroeder (5) Fly ash without Hg

control 3 0.074–1.67 Column with

H 2 O/

HAc/

Na 2 CO 3 /

SP/

H 2 SO 4 3 12.2–47.8 ng/g

44.7–1614.8

6.69–517.0

0.39–9.34

12.2–68.3

Kim and Schroeder (5) Fly ash with Hg control 6 0.348–92.1 Column with

H 2 O/

HAc/

Na 2 CO 3 /

SP/

H 2 SO 4 6 2.74–845.8 ng/g

35.5–410.1

8.04–1263.1

2.71–464.8

4.15–147.7 Withum (6) Fly ash 17 0.06–1.49 Batch leaching at pH 2.8/ pH 4.9/

DI H 2 O 17

All <1

All < 1

All <1 Withum (6) FGD sludge (not fixa ted) 5 0.21–0.65 Ba tch leaching at pH 2.8/ pH 4.9/

DI H 2 O 5

<1–10.9

<1–5.2

All <1 Withum (6) FGD sludge (fixated) 9 0.26–0.90 Batch leaching at pH 2.8/ pH 4.9/

DI H 2 O 9

<1–6.6

<1–2.5

All <1 Withum (6) FGD gypsum 3 0.33–0.52 Batch leaching at pH 2.8/ pH 4.9/

DI H 2 O 3

All <1

All <1

All <1 Withum (6) Bottom ash 2 0.01–0.04 Batch leaching at pH 2.8/ pH 4.9/

DI H 2 O 2

All <1

All <1

All <1 Hower et al. (7) Fly ash 85 0.000–0.894 Hower et al. (7) Bottom ash and boiler slag 27 0.000–0.086

Hower et al. (7) FGD (predominantly sulfate) 7 (Av value) 0.176

Hower et al. (7) FGD (predominantly sulfite) 3 (Av value) 0.463

Gustin (8) Fly ash without mercury

control Batch leaching

SPLP 23 0–8 ng/L

Gustin (8) Fly as h with activated

carbon Batch leaching

SPLP 9 0–2 ng/L

Gustin (8) FGD Batch leaching

SPLP 8 0–4 ng/L

Starns (9) Fly ash without mercury control (baseline) 2 291–734 ng/g Batch leach ing 2 <0.0002 mg/L

Starns (9) Fly ash with activated

carbon 2 1250–1520 ng/g Batch leach ing 2 <0.0002 mg/L35 without and with mercury emission controls present. These data are presented as ranges reported by the referenced researchers and may include data reported previously.

Hower et al. (10) also investigated the mercury concentrations of fly ash collected in various hoppers of an ESP at one power plant. He concluded that mercury capture is fairly uniform through an ESP system.

Leaching 1

Table 6 also summarizes recent leaching data reported in several forums since October 2005. EPA has performed leaching tests on a vari ety of CCB samples including fly ash samples with activated carbon, fly ash from systems with SCR on and off, and FGD materials (11), but no data were reported for inclusion in this update. The available leaching data indicate strong agreement among researchers (3–6, 8–9) that the mobility of mercury from direct leaching is very limited. In fact, the researchers (3, 5) have concluded that:

• The leachate concentrations of mercury do not correlate to total mercury concentrations for fly ash samples.

• Mercury in CCBs has extremely low mobility based on direct leaching.

Researchers (3, 5, 9, 12, 13) also all have reported that a range of leaching methods and leachate solutions provide similar results indicating extremely low concentrations of mercury in leachates. They and Schroeder (3, 5, 11) all ha ve indicated that leachates from CCBs have mercury concentrations below the Drinking Water maximum contaminant level (MCL) of 0.002 μg/mL. Thornloe (11) also stated that te st values for mercury leachates indicate that engineering controls for CCB disposal are protective when compared both with MCL and the recommended ambient water quality criteria. Other data reported (3, 8) on leaching of fly ash samples without and with mercury control (activated carbon) indicated that the leachate concentrations of mercury are lower from fly ash with activated carbon present than fly ash that was generated without mercury controls, even though the total mercury content can be significantly higher for samples with activated carbon.

Vapor Release 2

Evaluations of potential for vapor-phase rereleas es both at elevated and ambient temperatures have been ongoing by several groups.

1 The authors of the various documents have reported data in several different formats. The following concentrations are equivalent: ppm (parts per million) = μg/g; ppb (parts per billion) = μg/kg, ng/g, μg/L; and ppt (parts per trillion) = pg/g, ng/L. The EERC has used ppm, ppb, and ppt to express concentrations associated with solid materials and vapor-phase releases. μg/L and ng/L have been used for concentrations in liquids such as leachate

concentrations.

2 The authors of the various documents have reported data in several formats. The following concentrations are equivalent: ppm (parts per million) = μg/g; ppb (parts pe r billion) = μg/kg, ng/g, μg/L; and ppt (parts per trillion) = pg/g, ng/L.36 Elevated Temperature Vapor-Phase Rerelease

Withum (6) performed volatilization tests on fly ash, FGD materials, spray dryer solids, and products that incorporated CCBs (aggregate, cement, and wallboard) at 100° and 140°F with a continuous Hg-free nitrogen purge. The experi ment duration was 6 months and indicated no detectable mercury loss from most samples; however, Withum did indicate that there were sampling and storage difficulties with the samples used in the effort. Hower et al. (10) used thermal gravimetric analysis (TGA) to evaluate the potential for mercury releases at elevated temperatures and concluded that mercury was not released until 300°C. Starns evaluated baseline fly ash samples (without mercury control) and co mparable fly ash samples with PAC from two different demonstrations of mercury emission controls for thermal stability and reported that for both demonstrations, the thermal stability of mercury increased when PAC was present in the sample, as evidenced by increased first mercury desorption peaks (240°C for baseline compared to 315°C for fly ash–PAC for one site and 358°C for baseline compared to 419°C for the fly ash– PAC from a second site). Pflughoeft-Hassett (3) generated mercury thermal desorption curves for 61 CCBs, including 36 samples without mercury control and 25 samples with mercury control. The samples were primarily fly ash but also included various types of FGD materials. Most samples generated either one or two mercury peaks with a range of 0–4 peaks. The temperature of the mercury peaks ranged from 256° to 750°C, with an average of 429°C. Some samples continued to show increasing mercury release at 750°C, so the peak temperature at which the mercury was released could not be determined. FGD materials tended to release mercury at a lower temperature than fly ash. Fly ash samples with activated carbon were more likely to indicate continued mercury release at 750°C than fly ash generated without any mercury controls present.

Ambient-Temperature Vapor-Phase Rerelease

Gustin et al. (8) reported on ambient-temperature releases for air–CCB mercury exchange experiments performed under varied laboratory conditions (temperature, time, light, and dark). Gustin also investigated the impact of loss on ignition (LOI) and moisture on mercury release in laboratory experiments. She concluded that deposition (or sorption) was the predominant atmospheric flux (air–CCB mercury exchange) for fly ash from bituminous and subbituminous coal. Fly ash from lignite was found to emit mercury. Fly ash with activated carbon present sorbed mercury from the atmosphere at a higher rate than fly ash without activated carbon. Wet FGD material had a higher potential to release mercury to the atmosphere than dry FGD material or fly ash, and water content greatly influenced emission or release rate.

The ambient-temperature release of mercury was also investigated by Pflughoeft-Hassett (3) on 19 CCB samples. In long-term release measurements, six of the samples showed overall mercury release and 13 samples showed overall mercury sorption. Pflughoeft-Hassett also indicated that a wet FGD material included in these experiments released considerably more mercury than fly ash or dry FGD as long as the sample remained wet, but after the water evaporated from the sample the mercury release rate slowed.37 Microbiologically Mediated Release

The EERC (3) continued its efforts to quantitate mercury rerelease from fly ash and FGD materials on exposure to microbiological activity. Improved methods were described and included measurement of the rerelease in the liquid phase as well as the vapor-phase for elemental and organomercury. Aerobic and anaerobi c glucose-fed conditions were used in the experiments on fly ash and wet limestone FGD filter cake material. The fly ash samples evaluated were both from lignite-fired power plants with total mercury contents of 0.689 μg/g and 0.785 μg/g. The FGD material had a mercury c ontent of 0.218 μg/g and a significant natural population of sulfate-reducing bacteria. The FGD ma terial had an average vapor-phase release of 0.13 pg/g/day under anaerobic conditions and 9.44 pg/g/day under aerobic conditions during a 3-week time period when the samples were being pH-stabilized with buffer addition. This release was attributed to the naturally occurring sulfate-reducing bacteria in the FGD material. Following the preliminary pH adjustment phase, the highest vapor-phase release of both elemental and organomercury was from the FGD material under aerobic conditions, even though it had the lowest level of total mercury. Analytical difficulties were noted and interfered with the final analysis of vapor-phase mercury release from the FGD material. The fly ash samples released similar levels of vapor-phase mercury in these experiments ranging from 0.036 to 0.147 pg/g/day elemental mercury and from 0.108 to 1.25 pg/g/day for organomercury. Organomercury was also measured in the liquid separated from these experiments. Again the FGD material had significantly greater concentrations of organomercury in solution compared to the fly ash samples with a release of ~1800 pg/g for anaerobic conditions and a release of ~400 pg/g for aerobic conditions. Fly ash releases were 70 pg/g and 170 pg/g for anaerobic conditions and 128 pg/g and 195 pg/g for aerobic conditions. The EERC i ndicated that the data were variable and that work would continue on the experimental release method and the analytical methods to address interference from sulfur in the samples and the development of mold in the samples during the experiments.

Field Studies of Mercury Releases

Disposal Site Water Evaluations

Withum (6) evaluated groundwater collected at active fly ash and FGD disposal sites using existing monitoring wells. No mercury was detected in any monitoring well samples. Ladwig (14) also collected and evaluated a variety of water samples from a large number of CCB disposal sites (including ash ponds, ash landfills, and FGD disposal sites) across the United States. Samples collected and analyzed were from the following locations depending on the site:

• Leachate wells

• Lysimeters

• Leachate collection systems

• Drive point

• Direct push

• Pond/seep grab

• Sluice lines38 Data were summarized by site type (see Figure 2), and Ladwig indicated that the mercury concentration range was low at 0.25 to 60 ng/L, w ith a median concentration of 3 ng/L. Methyl mercury was generally less that 1 ng/L, and di methyl mercury was usually not detected.

Field Vapor-Phase Releases

Xin et al. (16) presented results of fiel d studies designed to determine mercury flux. A variety of disposal sites at facilities utilizing bituminous, subbituminous, and lignite were included in Xin’s work. Table 7 summarizes Xin’s findings.

A summary of similar work also performed by University of Nevada Reno (UNR) indicated that field data were consistent with laboratory data, with bituminous and subbituminous fly ash disposal sites sorbing mercury from the atmosphere, while lignite-derived fly ash exhibited emissions even though in the field that emission rate was low and comparable to surrounding soil (8).

The EERC collected mercury from ambient air at near-surface locations at one field site in conjunction with the UNR work (16) and quantitated the concentrations of elemental and organomercury. Elemental mercury concentration ranged from 0.541 ng/m 3 (the FGD + bottom ash and mill rejects) to 1.456 ng/m 3 (above FGD + mill rejects). Samples collected above natural grassland upwind from the associated power plant had 0.640 ng/m 3 of mercury. For organomercury, the sample collected above the natural grassland gave a reading of 0.017 ng/m 3

. Samples collected above various disposal sites ranged from 0.006 ng/m 3 (FGD + pyrite) to

Figure 2. Field leachate – mercury speciation (15).39 Table 7. Summary of Field Mercury Flux Data Presented by Xin et al. (16)

Coal Type Used at

Associated Power Plant Material Type Where Flux

Measurements Were Taken Mercury Flux (+ indicates release, - indicates sorption), ng/m 2 hr

Bituminous–

Subbituminous Blend Vegetated top soil over fly ash -0.1

Bituminous–

Subbituminous Blend Barren fly ash +0.9

Bituminous–

Subbituminous Blend Background soil +0.5

Lignite Vegetated top soil over fly ash +1.1 Lignite Barren fly ash +1.1 Lignite Unstabilized wet FGD material +0.8 Lignite Wet FGD material + fly ash or pyrite +11.2 or +10.9

0.354 ng/m 3 (FGD + fly ash); however, the value measured for the FGD + fly ash was significantly higher than other values (0.006–0.052), and the standard deviation was also high.

Rerelease of Mercury from CCBs in Select Utilization Applications

Gustin et al. (8) used outdoor experiments to evaluate the potential for rerelease of mercury from CCBs. Her experiments were designed to simulate soil stabilization, compacted CCB pads, and agricultural soil amendment, and while work will continue, preliminary data indicated that the mercury flux from CCB-amende d substrates was not significantly different from soils used. Golightly et al. (17) captured the volatile mercury species in air directly above curing concrete specimens. The specimens included OPC (ordinary portland cement) concrete, concrete with 33% fly ash added, concrete with 55% fly ash added, and concrete with 33% fly ash and 0.5% mercury-loaded PAC. Sampling was performed at 2 days, 28 days, and 56 days during dry curing at 40°C. Results are shown in Table 8. Golightly et al. (17) concluded that laboratory experiments suggested that curing fly ash concretes contribute little to global anthropogenic mercury emissions but that field work needs to be performed.

Another area of investigation of potential re release of mercury from CCBs has focused on FGD gypsum which is used in the production of wallboard. Since gypsum (natural or byproduct) needs to be calcined before use in the wallboard-manufacturing process, questions have been raised as to the potential for mercury to be released during the calcining or other phases of the process. Heebink et al. (18) performed la boratory investigations on an FGD gypsum designed to simulate two types of gypsum calcining (ke ttle and flash). Heebink reported a range of releases from <0.4%–28% of total mercury content present in the FGD gypsum samples evaluated, and Heebink concluded that there was potential for mercury to be released from FGD gypsum in the calcining process used in wallboard-manufacturing plants and that release appeared to be related to total mercury content of the gypsum being used.40 Table 8. Mercury Emission from Dry-Curing Concretes Mass Release Rate, ng/day/kg

Curing Interval OPC

Concrete FA33

Concrete FA55

Concrete HgPAC

Concrete

n 4 6 3 4 First 2 Days [40 ± 1 °C] 0.07 ± 0.02 0.13 ± 0.07 0.08 ± 0.07 0.26 ± 0.04

First 28 Days [40 ± 1 °C] 0.10 ± 0.03 0.26 ± 0.04 0.34 ± 0.09 0.43 ± 0.12

n 2 0 1 2 Additional 28 Days, [23°C ≤ T ≤ 40°C] 0.08 ± 0.05 – 0.10 0.11 ± 0.01

Initial Mercury

Concentration in Concrete, μg/kg 4.1 9.2 12.6 22.4

Marshall et al. (19) reported on an evaluati on of mercury releases from FGD gypsum at a variety of full-scale wallboard plants using FGD gypsum from several sources. The effort included an evaluation of mercury releas es from gypsum drying, gypsum calcining, and wallboard drying. Using Ontario Hydro and solids analysis, Marshall reported that the mercury releases ranged from 2.3% to 55% of the total mercury content of the FGD gypsum for all wallboard processes evaluated and estimated that a wallboard plant could potentially emit approximately 71 lb of mercury per year. In laboratory experiments, Kairies et al. (20) investigated the distribution of mercury in FGD gypsum and found that FGD gypsum is 99% soluble using a continuous stirred reactor, but th at the remaining 1% solid residue contained 100% of the mercury present in the original FGD gypsum sample. Wallboard solubility was similar, with 2% residue remaining containing 100% of the mercury from the original wallboard. Experiments were also designed and performed to determine the partitioning of mercury when FGD gypsum settles. These experiments indicated that after settling, the majority of the mercury was present in the top layer, while the bottom layer had very low mercury content. The top layer was also enriched in iron, and Kairies et al. ( 20) concluded that an iron-containing phase is responsible for sorption of mercury.

Summary

A large amount of work has been accomplished and reported related to the rerelease of mercury from CCBs since October 2004. The rerelease mechanism that has the most data available is that of direct leaching. Direct leach ing evaluations have been performed primarily on fly ash, with limited activities on FGD materials. Several groups have reported similar results from leaching tests of fly ash generated both w ithout and with mercury controls. The reports reviewed generally indicated that direct leachi ng of mercury from fly ash, even with elevated mercury concentrations, is not expected to require changes to current fly ash management options.41 The remaining mechanisms, vapor-phase rerelease and microbiologically mediated leaching and vapor-phase rerelease, have also been investigated during the past year, with additional information reported in the literature. However, the data available are still too limited for conclusions to be drawn. For the vapor-phase rerelease evaluations, results reported from studies performed by different investigators indi cated similar ranges of rerelease or sorption from similar materials. To date, the microbiologically mediated rerelease work has been limited to work performed at the EERC under a DOE N ETL and industry-funded project. It is also noteworthy that the field-generated data are consistent with the reported laboratory data even though only limited field investigations have been performed.

When the DOE NETL-funded project to conduct research on by-products generated from large-scale mercury emission control demonstrations is initiated, it is anticipated that a large number of CCB samples will be evaluated for mercury volatilization and leaching (both abiotic and biotic). The data from this study will help to fill the existing data gaps and contribute to the information available to aid the CCB industry in making decisions on management of CCBs that have been impacted by mercury emission controls.

References

1. American Coal Ash Association. ACAA Newsletter. www.acaausa.org/ACAA%20E%20Newsletter/Sep-2005_N ewsletter.htm#DOE (accessed Oct 2005).

2. Starns, T.; Bustard, J.; Durham, M.; Lindsey, C.; Martin, C.; Schlager, R.; Donnelly, B.; Sjostrom, S.; Harrington, P.; Haythornthwaite, S.; Johnson, R.; Morris, E.; Chang, R.; Renninger, S. Full-Scale Test of Mercury Control with Sorbent Injection and an ESP at

Wisconsin Electric’s Pleasant Prairie Power Plant. Presented at the Air & Waste Management Association Annual Meeting, Session AE1-C, 2002.

3. Pflughoeft-Hassett, D.F. Mercury and Air T oxic Element Impacts of Coal Combustion ByProduct Disposal and Utilization. Presented at the U.S. Department of Energy National Energy Technology Laboratory Mercury Contro l Technology R&D Program Review, July

2005.

4. Schroeder, K.; Kairies, C. Distribution of Mercury in FGD Byproducts. Presented at the 2005 World of Coal Ash (WOCA), Lexington, KY, April 2005.

5. Kim, A.G.; Schroeder, K. Factors Controlling the Solubility of Mercury Adsorbed on Fly Ash. Presented at the 2005 World of Coal Ash (WOCA), Lexington, KY, April 2005.

6. Withum, J. Characterization of Coal Com bustion By-Products for the Re-Evolution of Mercury into Ecosystems. Presented at the U.S. Department of Energy National Energy Technology Laboratory Mercury Control T echnology R&D Program Review, July 2005.42 7. Hower, J.C.; Robl, T.L.; Anderson, C.; Thomas, G.A.; Sakulpitakphon, T.; Mardon, S.M.; Clark, W.L. Characteristics of Coal Combus tion Products (CCPs) from Kentucky Power Plants, with Emphasis on Mercury Content. Fuel 2005

, 84 , 1338–1350.

8. Gustin, M.; Xin, M.; Ladwig, K.; Pflughoeft-Hassett, D.; Ericksen, J.; Swain, E. Coal Combustion By Products: Do We Need to Worry about Hg Releases. Presented at Air Quality V: International Conference on Mercury, Trace Elements, SO 3 , and Particulate Matter, Arlington, VA, Sept 2005.

9. Starns, T.; Sjostrom, S.; Amrhein, J.; Sapp, C.; Wilson, C.; Zipp, E.; Senior, C. Evaluation of Fuel Samples and Process Byproducts form Full-Scale Mercury Control Evaluations Conducted on Coal-Fired Boilers Burning PRB Fuel. Presented at Air Quality V: International Conference on Mercury, Trace Elements, SO 3 , and Particulate Matter, Arlington, VA, Sept 2005.

10. Hower, J.; Rubel, A.; Mardon, S.; Perrone, R. Thermal Stability of Mercury Captured by Fly Ash. Presented at the Western Fuels Symposium, Billings, MT, Oct 2004.

11. Thorneloe, S. Atmospheric Protection Branch/NRMRL. Personal communication, 2005.

12. Schroeder, K.; Cardone C.; Hesback, P.; Kairies, C., Kazonich, G.; Kim, A. NETL In-House Characterization of Mercury in Coal Com bustion By-Products. Presented at the U.S. Department of Energy National Energy Technology Laboratory Mercury Control Technology R&D Program Review, July 2005.

13. Lockert, C.A.; Zhou, Q.; Zhang, Y.; Nelson, S. Further Progress Toward Concrete-Friendly Mercury Sorbents. Presented at Air Quality V: International Conference on Mercury, Trace Elements, SO 3 , and Particulate Matter, Arlington, VA, Sept 2005.

14. Ladwig, K. Speciation and Attenuation of Arse nic and Selenium, and Fate of Mercury in CCPs. Presented at the U.S. Department of Energy National Energy Technology Laboratory Mercury Control Technology R&D Program Review, July 2005.

15. Ladwig, K. Mercury in Coal Combustion Products. EPRI, Palo Alto, CA: 2005. 1010061.

16. Xin, M.; Gustin, M.S.; Ladwig, K. Mercur y Release from Coal Combustion Products; Presented at the 2005 World of Coal Ash (WOCA), Lexington, KY, April 2005.

17. Golightly, D.W.; Sun, P.; Cheng, C.; Taerakul, P.; Walker, H.W.; Weavers, L.K.; Wolfe, W.E.; and Golden, D.M. Mercury Emissions from Concrete Containing Flu Ash and mercury-Loaded powdered Activated Carbon; presented at the 2005 World of Coal Ash (WOCA), Lexington, KY, April 2005.

18. Heebink, L.V.; Hassett, D.J. Mercury Release from FGD. Presented at the 2003 International Ash Utilization Symposium; Special Issue of Fuel 2005

, 84 (11), 1372–1377.43 19. Marshall, J., Blythe, G.M.; Richardson, M.; Rhudy, R. Fate of Mercury in Synthetic Gypsum Used for Wallboard Production, Task 1. Presented at Air Quality V: International Conference on Mercury, Trace Elements, SO 3 , and Particulate Matter, Arlington, VA, Sept

2005.

20. Kairies, C.L.; Schroeder, K.T.; Cardone, C.R. Distribution of Mercury in FGD Materials. Presented at Air Quality V: International Conference on Mercury, Trace Elements, SO 3 , and Particulate Matter, Arlington, VA, Sept 2005.44 MERCURY FUNDAMENTALS (QUARTER 5 REPORT)

A review of the fundamental chemical princi ples of sorbent control of mercury in coal combustion flue gas was recently presented in Quarter 5. This update will summarize some of the earlier discussion as well go into more depth in certain areas of sorbent science. Understanding these fundamentals is critically important in the ongoing efforts to improve mercury capture and lower emissions from combustion sources. For low-chlorine coals, much of the mercury in the flue gas is elemental (Hg 0 ), and only a small amount is oxidized Hg(II), but finely powdered sorbent injection upstream of a particulate collection device has the potential to capture both elemental and oxidized mercury present in the flue gas.

There are several facts and ideas that have been developed in the last few years that are critical to understanding how the capture of mercury takes place on a carbon sorbent in a flue gas stream. Several unequivocal pieces of evidence demonstrated that the sorption at elevated temperatures occurs via an oxidation mechanism (chemisorption) rather than physisorption. The most important evidence is the results of the examination of spent sorbents using x-ray absorption fine structure (XAFS). These studies showed that only Hg (II) was present (1).

Flue Gas Effects

Based on results from an extensive matrix of tests at the EERC using full and partial gas compositions (2), a preliminary chemisorption model was developed (3). The model showed both oxidation of elementary mercury on the car bon surface and binding of the oxidized mercury to a basic site on the carbon surface. The model was supported by x-ray photoelectron spectroscopy (XPS) data for a number of experiments where a sorbent was exposed to various synthetic flue gas compositions for varying lengths of time (4). These data demonstrated the competitive role of the acidic flue gas components and sulfuric acid formed by oxidation of SO 2 at the basic binding sites on the carbon. An updated version of this chemisorption-competitive binding model is shown in Figure 3. NO 2 is shown to effect the oxidation of SO 2 to H 2 SO 4 or HSO 4

- on the carbon surface, a reaction that also requires H 2 O. Note, however, that the details of the mercury oxidation reaction as well as the SO 2 oxidation are not included nor are the

interactions of SO 3 . Thus this illustration is an overview of the reactions on the carbon, with no

mechanistic details.

Carbon Structure Effects

Published information of the effect of car bon structure on the capacity or reactivity of sorbents is very scant. The effect of oxygen functional groups on the sorbent surface was investigated by Ghorishi et al. (5), but they found no correlation with mercury capture. Regarding the effect of carbon crystallinity, there is little except the recent report by Rostam Abadi et al. (6). The capture of mercury on the unburned carbon (UBC) of fly ashes was examined, with very careful attention to the par ticle size and structural organization of the UBC fractions from three different ashes (6). The UBC content decreased with decreasing particle size for all three ashes. There was no correlation between the mercury content and UBC content of different size fractions; however, mercury cont ent of unburned carbons in each size fraction45 Figure 3. Overview of mercury flue gas interactions on an activated carbon sorbent.

increased with decreasing particle size for the th ree ashes. After a normalization with respect to surface area, the data showed a more pronounced dependence on size for the FA1 (baghouse ash). The implications are that the size of the FA1 UBC and the surface area both contributed to the capture, whereas for FA2 (ESP ash) UBC particles size had a larger effect on mercury capture than the surface area, and for FA3 baghous e UBC, the size had a larger effect than

surface area.

Comparison of the x-ray diffraction (XRD) spectra of UBCs with activated carbon and with graphite, showed that the UBCs have a less disordered structure than activated carbon. Thus the higher temperature in the combustion system resulted in more extensive ordering and consequently lower surface areas than activated carbons and lower mercury capture potential. The FA3 UBC was the most ordered and exhibited the lowest mercury capture. The implications for mercury capture in coal-fired boilers are that decreasing the UBC size will result in more capture. Also a lower temperature history for the UBC would result in less ordered carbon structures that are favored for mercury capture.

Acid Promotion Effects

In early work, an increase in sorption was observed when HCl was added to flue gas (7), but the reason for the success of this strategy was unknown. It is clear that HCl is not an oxidizing reagent, since it is already in the most reduced state. The possibility of a Deacon reaction of HCl with oxygen on the carbon sorbent could account for generation of an oxidant on the sorbent surface. In the test matrix conducted at the EERC (2), when relatively high HCl concentrations (50 ppm) typical of eastern bituminous coals were used, the capture of mercury at46 the start was always very high (less than 5% of inlet concentration), but in very low HCl concentrations (1 ppm), such as those obtained when low-Cl coals are burned, an initial breakthrough was observed at only about 50%

B 60% of inlet (8), followed by an increase in capture efficiency to the 5%–10% level (Figure 4). The higher HCl concentration thus eliminated this induction period where poor capture is obtained (9). Since the increased sorption activity is seen from the very start of exposure to the flue gas, this increased activity is clearly a kinetic effect and therefore results from a promotiona l effect of the HCl on the carbon sites catalyzing the oxidation of mercury (9).

XPS studies of carbons exposed to synthetic fl ue gas showed that in either high-HCl or low-HCl conditions, the chlorine concentration on the carbon surface builds up at first, but then diminishes at breakthrough when the sulfuric acid displaces the bound chlorine (4, 10). These studies showed that the chlorine is present mainly in two forms, organochlorine and chloride ion.

An increase in capacity for carbons that were pretreated with dilute aqueous HCl was reported by Ghorishi et al. (5). The effect was observed in both nitrogen and synthetic flue gas. Experimentation at the EERC (9) showed that the main effect was the same as that observed for flue gas containing HCl, as discussed above. A more detailed chemical model of the carbon bonding site was introduced (11) to explain the bonding of the HCl, Hg(II), and the competition with the poisoning agent the sulfuric acid generated by oxidation of SO 2 on the sorbent. The model, shown in Figure 5, uses the concept of zigzag carbene edge structures recently proposed by Radovic and Brockrath (12). The zig zag carbon flanked by the aromatic rings has an electron pair and is the basic binding site for which the HCl, H 2 SO 4 , and Hg(II) compete, as shown on the left side of the figure, forming a positive carbenium ion intermediate in each case.

Figure 4. Breakthrough curves for high and low acid gas.47 Figure 5. Mercury and acid gas-binding mechanism at carbon edge.

Mercury Oxidation Mechanism

Several features of the oxidation site were inferred from the HCl promotion and bonding effects (9) that led to development of a more comprehensive model (Figure 6) of the chemical mechanism of mercury capture (9, 13, 14). This mechanism uses a single carbon site for oxidation and bonding but in two different forms a nd thus offers more chemical detail on the nature of the oxidation-bonding site and its interaction with flue gases and mercury. The model thus provides a detailed mechanism for the catalytic role of acids, such as HCl, in the oxidation step. The conversion of carbene to carbenium i on by HCl and other acids generates the oxidation site (Lewis acid). The mechanistic model shows Hg 0 oxidation by the carbenium cation to the organomercury intermediate and subsequent oxidation by NO 2 to the bound Hg(II) species. At the breakthrough point, HgCl 2 is continuously released as sulfuric acid drives the formation of the carbenium sulfate. Comparative testing of a large number of acid-promoted AC showed that they exhibit a specific acid catalysis, not a general acid catalysis. That is, those acids with polarizable counterions (HI>HBr>HCl) show fast er initial rates compared with strong and weak oxyacids and fluoroacids (13). This finding is consistent with a mechanism where the halide ion proximate to the cation actually can assist in the oxidation mechanism by stabilizing the incipient mercurinium ion forming in the transition state.

Halogenated Carbons

It has been known since 1934, when the first patent for mercury sorption was granted, that adding molecular halogens such as chlorine (Cl 2 ), bromine (Br 2 ), or iodine (I 2 ) to carbons results in effective sorbents for Hg 0 capture in air (15). The first application used iodine as the halogen,48 Figure 6. Oxidation mechanism – carbenium ion oxidant.

but later applications used chlorine (16) a nd bromine (17) or a mixed halogen compound (18). Originally, the model for this type of sorbent was that the halogens on the carbon were responsible for reactions with the Hg 0 , but a considerable amount of chemical evidence (19) showed that the halogens that are impregnated into carbon react with the carbon and are strongly bound to the carbon. So it is more likely that the halogens promote the reactivity of the carbon, as we have demonstrated for HCl, rather than react as such with the Hg 0

.

To provide greater insight into the mechanisms for mercury capture on a chlorine-treated sorbent, a comparison of the structures and mercury sorption activities of several carbon sorbents that had been subjected to various chlorine treatments was recently conducted (20). The NORIT FGD carbon was pretreated with gaseous HCl, aqueous HCl, and gaseous Cl 2 . All the pretreated sample showed high initial activity for capture, and thus the induction peak has been eliminated. Exceptionally high capacities were not observed since the ability to oxidize SO 2 to sulfuric acid, the main position of the binding sites, is not impaired by the chlorination.

Several of the pretreated sorbents were exposed to flue gas containing elemental mercury for various lengths of time, and the samples were analyzed with XPS. The Cl spectra of the pretreated samples that had not been exposed to flue gas showed peaks corresponding to both organochlorine and inorganic chloride. No clearly resolved peaks for physisorbed or intercalated molecular chlorine were found, but some may have been present in the wings of the organochlorine peak at high energy. As a result of exposure to the flue gas for a short time (20 min), all the chlorine-treated samples lost chlorine, but mainly the inorganic chloride. This could have been lost as HCl via displacement by sulfuric acid as it began to accumulate, as predicted by the model. Heating the chlorinated sorbents in air or an inert gas did not evolve

either HCl or Cl 2 , so the chlorine is strongly bound and must be exchanged or reacted off the49 carbon by a strong acid. Further exposure to flue gas resulted in further loss of both organochlorine and inorganic chloride. Although thes e chlorine spectra indicate the structures of the chlorine but not the mercury, the results contribute to our understanding of the reactive sites and allow us to extend the model to the chlorinated sorbents with little modification (see Figure 5).

The mechanism depicted in Figure 7 shows chlorination of the carbon edge structure to form the organochlorine species, consisting of the dichloro intermediate in equilibrium with the chlorocarbenium chloride ion pair. The latter represents the active oxidation site for elemental mercury, and the result of the oxidation is the organomercury chloride. The breakthrough mechanism proceeds as with the unchlorinated carbon (Figure 6).

Potential for More Effective Capture

Owing to the high reactivity of the halogenated carbons, full-scale testing of these sorbents is being conducted. Preliminary results show that indeed the halogenated carbon capture mercury more effectively and faster. Since improved capture is found in ESP systems for halogenated carbon injection, the capture is not mass transfer-limited even in these short contact time

situations.

Figure 7. Mercury oxidation mechanism for chlorinated carbon.50 A better understanding of the interactions and effects of flue gas constituents and conditions has resulted in an improved mechanistic model and the development of more improved sorbents for mercury capture and control. We can actually derive and compare rate constants for the oxidation reactions. Ultimately, the refined model will have the potential to be used to describe carbon–Hg–flue gas rates and equilibria for various kinds of carbons and to predict capture rates under a variety of conditions. Based on the developed models, capture rates for given sorbent loadings have increased. These embellishments to the sorbent comprise variations of the cation and anion structures in the oxidation site, but exact details cannot be revealed until patent protection has been acquired.

References

1. Huggins, R.E; Yap, N.; Huffman, G.P., Senior, C.L. Fuel Process. Technol. 2003

, 82, 167.

2. Miller, S.J.; Dunham, G.E.; Olson, E.S.; Brown, T.D. Fuel Process. Technol. 2000

, 65

B 66

, 343

B 363.

3. Olson, E.S.; Laumb, J.D.; Benson, S.A.; Dunham, G.E.; Sharma, R.K.; Miller, S.J. Pavlish

J.H. Prepr. Pap.

C Am. Chem. Soc., Div. Fuel Chem. 2002

, 47 (1), 481.

4. Laumb, J.D.; Benson, S.A.; Olson, E.S. Fuel Process. Technol. 2004

, 85 (6

B 7), 577

B 585.

5. Ghorishi, S.B.; Keeney, R.M.; Serre, S.D.; Gullet, B.K.; Jozewicz, W.S. Environ. Sci

. Technol

. 2002

, 36 , 4454–4459.

6. Rostam-Abadi, M.; Lu, Y.; Funk, C.; Richardson, C.; Paradis, J.; Chang, R. In Proceedings of Air Quality V: Mercury, Trace Elements, and Particulate Matter Conference ; Arlington, VA. Sept 19–21, 2005.

7. Granite, E.J.; Pennline, H.W.; Hargis, R.A. Ind. Eng. Chem. Res

. 2000

, 39 , 1020–1029.

8. Pavlish, J.H.; Holmes, M.J.; Benson, S.A.; Crocker, C.R.; Galbreath, K.C. In Proceeding of Air Quality III, Mercury, Trace Elements, and Particulate Matter Conference ; Sept 9

B 12,

2002.

9. Olson, E.S.; Laumb, J.D.; Benson, S.A.; Dunham, G.E.; Sharma, R.K.; Mibeck, B.A.; Miller, S.J.; Holmes, M.J.; Pavlish, J.H. An Improved Model for Flue Gas

B Mercury

Interactions on Activated Carbons. In Proceedings of the Combined Power Plant Air Pollution Control Mega Symposium ; Washington, DC, May 19

B 22, 2003.

10. Olson, E.S.; Crocker, C.R.; Benson, S.A.; Pavlish, J.H.; Holmes, M.J. J.AWMA, 2005, in

press.

11. Olson, E.S.; Laumb, J.D.; Benson, S.A.; Dunham, G.E.; Sharma, R.K.; Miller, S.J.; Pavlish,

J.P. Prepr. Pap.

C Am. Chem. Soc., Div. Fuel Chem. 2003

, 48 (1), 30

B 31.51 12. Radovic, L.R.; Bockrath, B. Prepr. Pap.

C Am. Chem. Soc., Div. Fuel Chem. 2002

, 47 (2),

428.

13. Olson, E.S.; Mibeck, B.A.; Benson, S.A.; Laumb, J.D.; Crocker, C.R.; Dunham, G.E.; Sharma, R.K.; Miller, S.J.; Pavlish, J.H. Prepr. Pap.

C Am. Chem. Soc., Div. Fuel Chem.

2004

, 49

.

14. Olson, E.S.; Laumb, J.D.; Benson, S.A.; Dunham, G.E.; Sharma, R.K.; Mibeck B.A.; Crocker, C.R.; Miller, S.J.; Holmes, M.J.; Pavlish, J.H. The Mechanistic Model for Flue

Gas

B Mercury Interactions on Activated Carbons. In Proceedings of the Air Quality IV: Mercury, Trace Elements, and Particulate Matter Conference ; Arlington, VA, Sept 22

B 24,

2003.

15. Stock, A. US Patent 1,984,164, 1934.

16. deJong, G.J.; Vos, H.J. US Patent 4,196,173.

17. Nelson, S.G. US Patent Appl. 20040003716, 2004.

18. Revoir, W.H.; Jones, J.A. US Patent 3,662,523, 1972.

19. Bansal, R.C., Donnet, J-B.; Stoeckli, F. Active Carbon ; Marcel Dekker: New York, 1988,

259.

20. Crocker, R.R.; Olson, E.S.; Mibeck, B.A. ; Sharma, R,K.; Benson, S.A.; Hill Brandt, K.L. In Proceedings of the 1st International Conference on Carbon for Energy Storage and Environment Protection; Orleans, France, Oct 2–6, 2005, p. 75.52 HEALTH ASPECTS OF MERCURY EMISSIONS (QUARTER 5 REPORT)

Mercury released into the atmosphere from coal-fired power plants is deposited in the environment, becomes methylated, and accumulates in fish as they grow and age. Because of the higher methylmercury (CH 3 Hg) concentrations present in larger and older fish, consumption of these fish may be associated with health risks. Th is is of special concern in the case of prenatally exposed children. Although the dangers of acute exposures to high doses of Hg are well recognized, controversy over fish consumption and the actual risks of CH 3 Hg ingestion continue.

Threshold levels for toxic effects of chronic e xposure to low-dose Hg have not been possible to agree upon since no biochemical marker of risk has been established. However, insights into the physiological effects of Hg poisoning have th e potential to reconcile these differences.

Dietary selenium’s ability to decrease the toxic action of Hg has been established in all investigated species of mammals, birds, and fish (1, 2). Since 1967, when the first report on the protective effect of Se against Hg toxicity app eared (3), numerous studies have shown that Se counteracts the negative impacts of Hg exposure. The Hg–Se interaction has previously been assumed to occur when supplemental Se complexes with Hg and prevents toxic effects in animals fed otherwise debilitating amounts of Hg (4–6). However, scientific understanding of this effect is rapidly changing.

Selenium is a nutritionally essential element required to support the activity of enzymes that are normally present in all cells of all cr eatures (7). Researchers are currently aware of 25 selenoproteins, many of which are enzymes whose activities appear to be especially important in the brain, pituitary, and thyroid since these ti ssues are virtually impossible to deplete of Se (58). The selenide formed during each cycle of selenocysteine synthesis has an exceptionally high affinity constant for Hg: 10 45 —a millionfold higher than Hg’s affinity for sulfide: 10 39 (8).

The high binding affinities between Se and Hg are clearly important in Se’s well-known protective effect against Hg toxicity. It has prev iously been assumed that Se’s protective effect was the result of Se-dependent binding of Hg, limiting its availability for causing harm in tissues. However, it is possible that instead of Se acting to immobilize Hg, Hg-dependent sequestration of Se could inhibit formation of se lenium-dependent proteins. These proteins are normally present in all cells of all creatures. Since these enzymes are essential to support normal enzyme metabolic functions, especially in brain tissues, excessive exposure to Hg would be expected to disrupt selenium-dependent processes that occur in the brain. Hg-dependent sequestration of Se that leads to inhibition of selenium-dependent enzyme functions may explain why selenium-deficient rodents are more susceptible to prenatal toxicity of CH 3 Hg than those fed Se-adequate diets. This mechanism would also explain why maternal exposure to CH 3 Hg reduced Se-dependent enzyme activity in the brains of fetal/neonatal rats (9).

The contrasting observations reported by studies of Hg exposure performed in fish-eating populations of the Seychelles and the Faroe Islands may be related to differences in Hg exposure relative to Se in the foods consumed by of their respective study populations.

In the Faroe Islands (10, 11), adverse associations from prenatal CH 3 Hg exposure have been found. Although adult Faroe Islanders consume ~72 g of fish a day, the fish they consume53 have relatively low total Hg contents: ~0.07 ppm. However, less than 10% of the Hg they consume comes from fish. The pilot whale meat they eat is quite high in Hg and accounts for more than 90% of their mercury exposure. Averaged daily consumption of ~12-g portions of pilot whale muscle meat is much lower than that of fish, but whale meat is most often consumed in intermittent feasts with relatively large meal portions. With total Hg contents of 3.3 ppm (~50 times higher than the Hg of the fish they eat), pilot whale meat provides the bulk of Hg exposure in this population. The level of mercury-dependent harm found in Faroese children that have been prenatally exposed to Hg has been quite subtle, but distinct.

This is in contrast to the results of the Seychelles Study where no adverse associations have been noted, even though the absolute Hg exposure appears similar. A critical difference is that in the Seychelles, ~100% of the Hg exposure comes from fish consumption. The Seychelles population consumes large quantities of fish with relatively low Hg levels (12), resulting in a Hg exposure that is ~10–20 times as great as typically occurs in North American diets. In the Seychelles measurements of neurodevelopmental outcomes, fish consumption by Seychellois mothers during pregnancy was not associated with harmful effect but, in some cases, was

associated with beneficial effects on their ch ildren, possibly as a result of improved nutrition (selenium and omega-3 fatty acid).

One explanation of the contrasting observations of the Faroe Islands and the Seychelles studies may be that they are observing dose-dependent differences that arise from intermittent exposures to high concentrations of Hg (characteristic of whale meat) as opposed to persistent low-level Hg exposures (characteristic of fish meat consumption). Another possibility that needs to be considered is that there are distinctions in the molar ratios of Hg and Se present in the foods consumed by their study populations.

Figure 8 shows the relative molar concentrations of Hg and Se present in fish and whale meats. The data displayed in Figure 8 were converted into molar concentrations in order to accurately compare Hg and Se contents in samples. Since 1 nmol Hg/g = 200.59 ppb; 1 ppm Hg =~5 nmol Hg/g; 1 nmol Se/g = 78.96 ppb, thus 1 ppm Se = ~12.6 nmol Se/g). Aside from pilot whale (13) and swordfish (14), data depicted in this figure originate from Hall et al. (15).

As is apparent in Figure 9, mercury is present at a ~fourfold excess in whale meat, but its relative abundance in fish is substantially less. Greater risks of maternal consumption causing neurodevelopmental harm in a developing fetus are associated with mercury occurring at molar ratios in excess of 1:1. Data shown were calculated from data displayed in Figure 8.

Fish samples collected from Minamata Bay contained as much as 40 ppm CH 3 Hg. Although Se contents were not measured in these fish, conservative estimates indicate the Hg:Se molar ratio in these fish would have been between 10 and 40 moles of Hg for every mole of Se. Children exposed in utero to Hg from these highly contaminated fish showed severe neurodevelopmental impairment, even though the mothers experienced minimal or no clinical symptoms (16).54 Figure 8. Molar relationships between mercury and selenium concentrations in seafood.

Figure 9. Molar ratio of mercury:selenium concentrations in seafood.55 The data shown in Figure 10 were calculated from data displayed in Figure 8. As is apparent in Figure 10, selenium is highly availabl e in fish meat but very poorly available from whale meat. Selenium’s protective effects against Hg would be among the benefits associated with Se-rich dietary intakes from fish consumption.

The first panel in Figure 11 reflects the relative effects of mercury exposure from pilot whale vs. fish consumption in the Faroes. Since the concentration of mercury in pilot whale meat is ~50 times as great as that of the cod consumed in the Faroes, the slopes of the dose response curves of blood mercury levels are quite different. Blood MeHg rises quite rapidly for each meal of whale meat and is equaled only after many m eals on fish. The graph reflects the approximated differences in exposure from whale feasts vs. normal fish meals. Because of the much greater time interval required to consume a similar quantity of MeHg, the natural depuration effects of exfoliation and hair growth diminish the intensity of the peak exposure from a similar mass quantity of MeHg from fish. Meanwhile, the second panel in Figure 11 depicts the relative effects of fish consumption vs. whale consumpti on on selenium status of the exposed individual. Each whale meal diminishes the selenium status of the consumer, meanwhile selenium status improves with each fish meal.

Recent work indicates the probl em of excessive Hg exposure from whale meat consumption is not limited to the Faroes. Concentrations of MeHg in 160 samples of red meat products from small cetaceans sold for human consumption in mark ets throughout Japan from 2000–2003 all exceeded the provisional permitted levels in fish and shellfish set by the Japanese Government,

Figure 10. Molar ratio of selenium:mercury concentrations in seafood.56 Figure 11. Relative effects of whale vs. fish consumption.

0.3 μ g MeHg/wet g (17). The average MeHg level in the most contaminated species (false killer whale) was 11.5 μ g MeHg/wet g. The molar ratio of total Hg to Se was substantially greater than 1. It is, therefore, believed that consumption of red meat products from small cetaceans could pose a health problem for not only pregnant women but also for the general population.

It is clear that the Se naturally present in all foods and abundant in ocean fish and other seafoods can provide significant protection agai nst Hg toxicity. However, it is becoming apparent that instead of merely being a protective “tonic,” Se is instead a potential “target” of Hg toxicity since the loss of Se-dependent enzymes undoubtedly contributes to Hg’s pathologic effects. As research on this issue accrues, it is apparent the tonic-to-target paradigm shift will foster new understanding of apparent discrepancies in results of various studies. Efforts to define interactions between Se and Hg continue to move forward as increasing numbers of research groups are investigating this emerging perspective of the Hg issue.

Environmental Hg

Progress is being made in understanding how to deal with environmental Hg, and new practices may lead to ways of reducing Hg contam ination of fish in freshwater lakes. Flooding of terrestrial areas stimulates MeHg production and l eads to increased bioaccumulation in fish (18). Burning greatly reduced plant and soil retention of total and methylmercury, diminishing the amounts available for bioaccumulation in fish. Although this approach contributes to the global atmospheric pool of elemental Hg, it may be valuable to apply to reduce the Hg contamination in fish that often occurs in reservoirs and other areas where dry–wet cycling happens.

The Guizhou Province in the southwest of China has areas of extremely high soil selenium and also has many areas with high accumulations of Hg. Elemental analysis of a coal sample from this province indicated Hg concentrations of 55 ppm, which is ~200 times the average Hg concentration in North American coals (19). Atmospheric emissions of Hg from mining, ore57 processing, chemical industry wastewaters, a nd coal burning for electricity production in Guizhou Province amount to ~12% of the world’s total anthropogenic emissions (20). As a result, even foods that are not normally known for mercury accumulation develop substantial and potentially hazardous burdens. The concentration of Hg in rice grains can reach up to 569 μg/kg of total Hg of which 145 μg/kg was in MeHg form. The percentage of Hg as MeHg varied from 5% to 83%. Although this area is rich in Se, it is not known if the inorganic Hg in the rice is in the less available HgSe form or not.

Physical factors controlling total Hg and MeHg concentrations in lakes and streams of the northeastern United States were assessed using multiple regression models using watershed characteristics and climatic variables (21). These factors explained 38% or less of the variance in mercury values. Methylation efficiency (MeHg/total Hg) was modeled well (r 2 of 0.78) when a seasonal term was incorporated. Their physical models explained 18% of the variance in fish Hg

concentrations in 134 lakes and 55% in 20 reservoirs.

The role of Se in reducing bioaccumulation of Hg in fish has been reported (22–24), and inverse relationships between fish tissue Hg and the abundance of Se present in the ecosystem have been noted (25, 26). Selenium supplementation of lake waters in Sweden resulted in a 75%–85% reduction in Hg levels of fish over a 3-year period (27), and loss of Se can have the opposite effect. When Se-rich discharges of fly ash to an artificial lake were removed, researchers noted a steady increase in Hg concentrations (28, 29). Studies such as these indicate the importance of Se-dependent Hg retirement in aquatic ecosystems, possibly through formation of insoluble Hg:Se complexes that deposit in sediments. Several studies of the relationships between Hg and Se are currently ongoing in Canada and elsewhere in the world.

References

1. Grandjean, P.; Weihe, P.; White, R.F.; Debes, F. Cognitive Performance of Children Prenatally Exposed to “Safe” Levels of Methylmercury. Environ. Res

. 1998

, 77 , 165–172.

2. Beijer, K.; Jernelov, A. Ecological Aspects of Mercury–Selenium Interaction in the Marine

Environment. Environ. Health Perspect

. 1978

, 25 , 43–45.

3. Parizek, J.; Ostadalova, I. The Protective Effect of Small Amounts of Selenite in Sublimate

Intoxication. Experiential

. 1967

, 23 (2), 142–143.

4. Culvin-Aralar, L.A.; Furness, R.W. Mercury and Selenium Interaction: A Review. Ecotoxicol. Environ. Saf

. 1991

, 21 , 348–364.

5. Suzuki, K.T. Equimolar Hg–Se Complex Binds to Selenoprotein P. Biochem. Biophys. Res.

Commun

. 1997

, 231 (1), 7–11.

6. Whanger, P.D. Selenium in the Treatment of Heavy Metal Poisoning and Chemical Carcinogenesis. J. Trace Elem. Electrolytes – Health Dis

. 1992

, 6 (4), 209–221.58 7. Southworth, G.R.; Peterson, M.J.; Ryon, M.G. Long-Term Increased Bioaccumulation of Mercury in Largemouth Bass Follows Reduction of Waterborne Selenium. Chemosphere

2000

, 41 (7), 1101–1105.

8. Behne, D.; Pfeifer, H.; Rothlein, D.; Kyriakopoulos, A. Cellular and Subcellular

Distribution of Selenium and Selenium -Containing Proteins in the Rat. In Trace Elements in

Man and Animals 10 ; Roussel, A.M.; Favier, A.E.; Anderson, R.A., Eds.; Kluwer Academic/Plenum Publishers: New York, 2000; pp 29–34.

9. El-Demerdash, F.M. Effects of Selenium and Mercury on the Enzymatic Activities and Lipid Peroxidation in Brain, Liver, and Blood of Rats. J. Environ. Sci. Health

. 2001

, 36 (4),

489–499.

10. Myers, G.J.; Davidson, P.W.; Cox, C.; Shamlaye, C.; Cernichiari, E.; Clarkson, T.W. Twenty-Seven Years Studying the Human Neurotoxicity of Methylmercury Exposure.

Environ. Res. Section A

. 2000

, 83 , 275–285.

11. Grandjean, P.; Weihe, P.; White, R.F.; Debes, F.; Araki, S.; Murata, K. Cognitive Deficit in 7-Year-Old Children with Prenatal Exposure to Methylmercury. Neurotoxicol. Teratol

. 1997

, 19 , 417–428.

12. Iyengar, G.V.; Rapp, A.S.O. Human Placenta as a “Dual” Biomarker for Monitoring Fetal and Maternal Environment with Special Reference to Potentially Toxic Trace Elements. Part

3: Toxic Trace Elements in Placenta and Placenta as a Biomarker for These Elements. Sci.

Total Environ

. 2001

, 280 (1–3), 221–238.

13. Julshamn K; Andersen A; Ringdal O; Morkore J. Trace Elements Intake in the Faroe Islands. I. Element Levels in Edible Parts of Pilot Whales (Globicephalus meleanus). Sci.

Total Environ

. 1987

, 65 , 53–62.

14. Freeman, H. C.; Shum, G.; Uthe, J. F. The selenium content in swordfish (Xiphias gladius) in relation to total mercury content. J. Environ. Sci. Health, Part A: Environ. Sci. Eng

. 1978

, A13 (3), 235–40.

15. Hall, R. A.; Zook, E. G.; Meaburn, G. M. National Marine Fisheries Service Survey of Trace Elements in the Fishery Resource. NOAA Tech. Rep., NMFS SSRF (1978) (NMFS SSRF-721), 313 pp.

16. Tsubaki, T.; Irukayama, K. Minamata Disease: Methylmercury Poisoning in Minamata and Niigata, Japan. Tokyo: Kodansha Ltd. 1977, 57–95.

17. Endo, Tetsuya; Haraguchi, Koichi; Hotta, Yohei; Hisamichi, Yohsuke; Lavery, Shane; Dalebout, Merel L.; Baker, C. Scott. Total Mercury, Methyl Mercury, and Selenium Levels in the Red Meat of Small Cetaceans Sold for Human Consumption in Japan. Environ. Sci.

Technol

. 2005

, 39 (15), 5703–5708.59 18. Mailman, M.; Bodaly, R. A. Total Mercury, Methylmercury, and Carbon in Fresh and

Burned Plants and Soil in Northwestern Ontario. Environ. Pollut . (Amsterdam, Netherlands)

2005

, 138 (1), 161–166.

19. Finkelman, R.B., Belkin, H.E., Zheng, B. Health Impacts of domestic coal use in China.

Proc. Natl. Acad. Sci

. 1999

, 96 , 3427–3431.

20. Horvat, M.; Nolde, N.; Fajon, V.; Jereb, V.; Logar, M.; Lojen, S.; Jacimovic, R.; Falnoga, I.; Liya, Q.; Faganeli, J.; Drobne, D. Total Mercury, Methylmercury and Selenium in Mercury Polluted Areas in the Province Guizhou, China. Sci. Total Environ

. 2003

, 304 (1–3), 231–

256.

21. Shanley, J.B.; Kamman, N.C.; Clair, T.A.; Chalmers, A. Physical Controls on Total and Methylmercury Concentrations in Streams and Lakes of the Northeastern USA. U.S. Geological Survey, Montpelier, VT, USA. Ecotoxicology 2005

, 14 (1&2), 125–134.

22. Boudou, A.; Ribeyre, F. Mercury in the Food Web: Accumulation and Transfer

Mechanisms. In Metal Ions in Biological Systems: Mercury and Its Effects on Environment and Biology ; Sigel, A.; Sigel, J., Eds.; Marcel Dekker: New York, 1997; pp 289–319.

23. Jin, L.; Guo, P.; Xu, X. Effect of Selenium on Mercury Methylation in Faculative Lake

Sediments. Toxicolog. Environ. Chem

. 1999

, 69 (1–2), 255–261.

24. Bjoernberg, A.A. Decontamination of Merc ury from Swedish “Black-Listed” Lakes by

Addition of Selenium. In Proceedings of the 4th International Symposium of Uses of

Selenium and Tellurium ; Carapella, S.C. Jr., Ed.; Banff, Canada: Selenium-Tellurium Dev. Assoc., Darien, CT, 1989, pp 357–360.

25. Chen, Y.W.; Belzile, N.; Gunn, J.M. Antagonistic Effect of Selenium on Mercury Assimilation by Fish Populations near Sudbury Metal Smelters. Limnol. Oceanogr

. 2001

, 46 (7), 1814–1818.

26. Zhang, P.; Chen, C.; Zhao, J.; Li, B.; Xing, L.; Qu, L.; Chai, Z. Correlations of Mercury, Selenium, and Other Elements in Fish Tissu es from the Regions at Different MercuryExposure Levels. In 7th International Conference on Mercury as a Global Pollutant ; Pezdic, J., Ed.; Ljubljana, RMZ-Materials and Geoenvironment

, 2004

, 51 , 1457–1460.

27. Glass, G.E.; Sorenson, J.A.; Austin, J.J.; Schmidt, K.W.; Kallemeyn, L.W.; Hedman, S.C.; Rapp, G.R. Mitigating Mercury in Minnesota Lakes and Streams ; Final Report to the Minnesota Pollution Control Agency and Legislative Commission on Minnesota Resources; 1995, pp 1991–1993.

28. Paulsson, K.; Lindbergh, K. The Selenium Me thod for Treatment of Lakes for Elevated Levels of Mercury in Fish. Sci. Total Environ

. 1989

, 87–88 , 495–507.60 29. Southworth, G.R.; Peterson, M.J.; Turner, R.R. Changes in Concentrations of Selenium and Mercury in Largemouth Bass Following Elimination of Fly Ash Discharge to a Quarry. Chemosphere 1994

, 29 (1), 71–79.61 COMMERCIALIZATION ASPECTS OF SORBENT INJECTION TECHNOLOGIES IN CANADA (QUARTER 8 REPORT)

The CAMR in the United States and the accepta nce in principle of a draft of the CWS for mercury illustrate the need for cost-effective mercury control strategies for coal-fired electric

utilities. Recent demonstration activities have s hown effective mercury capture with sorbent injection at full-scale systems. Out of this effort, concerns have been raised regarding the availability of carbon, sorbents, additives, and the related capital equipment if there were widespread adoption of ACI technology.

Issues that relate to the state of commercialization of sorbent injection technologies include the following:

• Policy and regulatory issues that impact commercialization of mercury sorbent technologies

• Sorbents most likely to be used based on coal type and plant configurations

• Capital investment requirements and the availability of necessary equipment and labor

• Availability of sorbents and/or additives

• Status of mercury measurement technology for compliance purposes

• Balance-of-plant impacts

Projections by the activated carbon industry do not suggest that either the availability of activated carbon or equipment will be a significant issue, although existing shortages in labor and construction materials are likely to continue, causing delays in capital improvements in Canada. Over the long term, there are several areas of concern that need to be addressed before widespread commercial implementation of sorbent injection technology can occur. These include the following:

• Environmental and economic impacts of lost fly ash utilization (greenhouse gas credits)

• The impact of ACI on FF and ESP performance

• Environmental impacts of treated carbon

• Longer-term leaching potential of disposed ash

A disadvantage of ACI is the impact the added carbon may have on ash salability. There are a large number of utilities in Canada and the United States that sell at least a portion of the ash collected to the concrete industry. In Canada, almost all the utilities burning lignite or subbituminous coal (SaskPower, TransAlta, EPCOR, and ATCO POWER) have facilities selling their ash for use as an admixture in place of portland cement at varying concentrations up to as high as 50%. A review of the impacts of mercury on by-product utilization was addressed in Quarter 4, Rerelease of Mercury from Coal Co mbustion By-Products, Therefore, any mercury control technology that prevents the sale of ash would have financial as well as environmental penalties. Increased ash to the landfill, forgone revenue from by-product sales, and increased energy consumption to manufacture portland cement not replaced with fly ash all directly result from activated carbon in fly ash. In some cases, as little as 1% carbon in the ash may result in rejection of the ash by the cement industry especially when from ACI. One method of preventing62 activated carbon from entering the bulk of the fly ash is to add a small baghouse after the ESP with ACI between the two particulate control units. The downside is the added capital cost associated with installing a baghouse and the additional operating cost of replacing bags and the pressure drop.

The long-term effect of ACI injection on particulate control devices is currently being investigated. Long-term demonstration activities in Canada and the United States are being funded that will provide data over periods of up to 1 year. Data from these activities should help quantify many balance-of-plant effects, including both effects on particulate control devices and fate of halogens and other enhancement additives used to improve mercury capture.

Research is also ongoing to evaluate the long-term leaching potential of mercury from combustion by-products. Limited testing to date has indicated that mercury is stable on the ash; however, results from testing over periods of many months will be necessary to illustrate that stability.63 UPCOMING EVENTS

Power-Gen International 2005 Conference & Exhibition December 6–8, 2005, Sands Expo & Convention Center, Las Vegas, NV http://pgi05.events.pennnet.com

Pittcon 2006 March 12–17, 2006, Orlando, FL www.pittcon.org

231st ACS National Meeting & Exposition March 26–30, 2006, Atlanta, GA www.chemistry.org

Coal Ash Professionals Training Course April 19–21, 2006, Memphis, TN www.undeerc.org

A&WMA Annual Conference & Exhibition June 20–23, 2006, New Orleans, LA

www.awma.org

Eighth International Conference on Mercury as a Global Pollutant August 6–11, 2006, Madison, WI www.mercury2006.org/Default.aspx?tabid+1393

The Mega Meeting: Power Plant Air Pollutant Control Symposium (formerly The MegaSymposium) August 28–31, 2006, Baltimore, MD www.megasymposium.org

Pittcon 2007 March 11–16, 2007, New Orleans, LA www.pittcon.org64 AUTHORS

Dennis L. Laudal, Stanley Miller, Debra Pflughoe ft-Hassett, Nick Ralston, Grant Dunham, and Greg Weber

CONTACT INFORMATION

For more information, please contact:

Michael J. Holmes Deputy Associate Director for Research Energy & Environmental Research Center

PO Box 9018 Grand Forks, ND 58202-9018 mholmes@undeerc.org (701) 777-5276

John H. Pavlish

Senior Research Advisor Energy & Environmental Research Center

PO Box 9018 Grand Forks, ND 58202-9018 jpavlish@undeerc.org (701) 777-5268

Chad A. Wocken Research Manager Energy & Environmental Research Center

PO Box 9018 Grand Forks, ND 58202-9018 cwocken@undeerc.org (701) 777-5273

Dennis L. Laudal

Senior Research Advisor Energy & Environmental Research Center

PO Box 9018 Grand Forks, ND 58202-9018 dlaudal@undeerc.org (701) 777-5138

# APPENDIX D

LABORATORY METHODS FOR THE

EVALUATION OF POTENTIAL RELEASE OF

MERCURY FROM COAL UTILIZATION BYPRODUCTS

# LABORATORY METHODS FOR THE

EVALUATION OF POTENTIAL RELEASE OF

MERCURY FROM COAL UTILIZATION

BY-PRODUCTS

Topical Report

Prepared for:

Ms. Lynn Brickett

U.S. Department of Energy National Energy Technology Laboratory

626 Cochrans Mill Road

PO Box 10940 MS 922-273C Pittsburgh, PA 15236-0940

Other Industrial Sponsors

Prepared by:

Debra F. Pflughoeft-Hassett

David J. Hassett Tera D. Buckley

Loreal V. Heebink

Erick Zacher

Energy & Environmental Research Center University of North Dakota

PO Box 9018 Grand Forks, ND 58202-9018

April 2005EERC DISCLAIMER

LEGAL NOTICE This research report was prepared by the Energy & Environmental Research Center (EERC), an agency of the Univ ersity of North Dakota, as an account of work sponsored by the U.S. Department of Energy, Center fo r Air Toxic Metals ® , Cynergy, Utility Solid Waste Activities Group, North Dakota I ndustrial Commission, and Great River Energy.

Because of the research nature of the work performed, neither the EERC nor any of its employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or re presents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or othe rwise does not necessarily consti tute or imply its endorsement or recommendation by the EERC.

DOE DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United

States Government. Neither the United States G overnment, nor any agency thereof, nor any of their employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not n ecessarily constitute or imply its endorsement, recommendation, or favoring by the United States G overnment or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

ACKNOWLEDGMENT

This report was prepared with the support of the U.S. Department of Energy (DOE) National Energy Technology Laborat ory Cooperative Agreement No. DE-FC21-93MC30098

. However, any opinions, findings, co nclusions, or recommendations e xpressed herein are those of the authors(s) and do not necessar ily reflect the views of DOE.i TABLE OF CONTENTS

LIST OF FIGURES ................................................................................................................ ........ ii

EXECUTIVE SUMMARY ...........................................................................................................iii

INTRODUCTION ................................................................................................................... ....... 1

BACKGROUND ..................................................................................................................... ....... 1

OBJECTIVES..................................................................................................................... ............ 3

METHODOLOGIES – ANALYTICAL AND CHARACTERIZATION METHODS ................. 4 Chemical and Physical Characterization ............................................................................... 4 Total Mercury ............................................................................................................... 4

Total Air Toxic Elements.............................................................................................. 4 Total Bulk Chemical Composition ............................................................................... 4

LOI and Moisture.......................................................................................................... 5 pH............................................................................................................................ ...... 5

Carbon Forms................................................................................................................ 5

Eh ............................................................................................................................ ...... 5 Method Used to Measure Mercury on Gold-Coated Quartz Traps........................................ 5 Method Used to Measure Mercury on Carbotraps................................................................. 6

METHODS FOR THE EVALUATION OF TH E RELEASE POTENTIAL OF MERCURY

AND OTHER AIR TOXIC ELEMENTS FROM CUB................................................................. 6 Direct Leaching............................................................................................................... ....... 6 Vapor-Phase Transport ......................................................................................................... . 8 Long-Term Ambient Temperature Release .................................................................. 8 Vapor-Phase Transport ........................................................................................................ 1 0 Thermal Desorption at Elevated Temperature............................................................ 10 Microbiologically Mediated Leaching and Vapor-Phase Transport.................................... 13

SUMMARY........................................................................................................................ .......... 16

REFERENCES ..................................................................................................................... ........ 17

DRAFT ASTM STANDARD METHOD FOR SYNTHETIC GROUNDWATER LEACHING PROCEDURE ..........................................................................................Appendix Aii LIST OF FIGURES

1 Information from EPA on mercury emissions........................................................................ 2

2 Long-term leaching results for boron ..................................................................................... 7

3 Indirect evidence of ettringite formation using SGLP and LTL............................................. 8

4 Mercury vapor release collection apparatus ........................................................................... 9

5 Average total long-term ambient-temperatur e mercury release or sorption as related

to blank values ................................................................................................................ ...... 10

6 Mercury thermal desorption apparatus ................................................................................. 11

7 Typical thermal desorption curve for fly ash........................................................................ 12

8 Example of thermal desorption curve for an FGD material ................................................. 12

9 Microbiologically mediated mercury vapo r-phase collection apparatus utilizing a wrist action shaker to facilitate mixing................................................................................. 14

10 Microbiologically mediated mercury va por-phase collection apparatus utilizing a stir plate to facilitate mixing ................................................................................................ . 14

11 Example of a SPME chromatogram ..................................................................................... 15iii LABORATORY METHODS FOR THE EVALUA TION OF POTENTIAL RELEASE OF

MERCURY FROM COAL UTILIZATION BY-PRODUCTS

EXECUTIVE SUMMARY

Under a 3-year effort funded by the U.S. Department of Energy (DOE) and industry entitled “Mercury and Air Toxic Element Impact s of Coal Combustion By-Product Disposal and Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of mercury and other air toxic elements on the mana gement of coal utilization by-products (CUBs). The EERC is measuring the rel ease of mercury and other air toxic elements under different controlled laboratory conditions and investigating the release of these same air toxic elements in select field settings. Results wi ll be used to determine if mercury release from CUBs, both as currently produced and as produced with mercury and other emission controls in place, will potentially impact CUB management practices. In order to adequately address the potential for release of mercury from CUBs, sorbents, and combinations, release mechanisms that must be evaluated include 1) leaching, 2) elevated- and ambient-temperature vapor-phase releases, and 3) microbiologically mediated releases. The EERC initiated research on the potential release of mercury from CUBs in 1999 and found that methodol ogies for evaluating the release of mercury from CUBs using these mechanisms were not docum ented in the scientific literature, with the exception of leaching. As a result, method deve lopment work was initiated under the U.S. Environmental Protection Agency (EPA) Center for Air Toxic Elements and the Coal Ash

Resources Research Consortium.

The EERC concluded Year 2 of this effort in April 2005, and this report details the results

to date from Task 2: An alytical Methods Selection. As noted in several forums in recent years, the

methods used to evaluate CUBs must be relevant to the material and th e management of CUBs where possible. EERC researchers reviewed me thods currently being used at the EERC and elsewhere to determine the best possible methods for this effort.

Laboratory methods were selected based on ear ly work performed at the EERC but method development and modification continued. The methods being employed to evaluate the release of mercury from CUBs by direct leaching, exposure to ambient and elevated temperatures, and exposure to biota are described, and method limitations are discussed.1 LABORATORY METHODS FOR THE EVALUA TION OF POTENTIAL RELEASE OF

MERCURY FROM COAL UTILIZATION BY-PRODUCTS

INTRODUCTION

The stability of mercury associated with coal utilization by-products (CUBs) has become a prominent question as the coal-fired utility indus try develops and tests mercury emission controls that may consequently increase the mercury asso ciated with CUBs. The reasons for evaluating the release of mercury from CUBs are 1) to determine if merc ury captured on CUBs is stable or if it will be released, thus negating the purpos e of the removal of the mercury from the emissions, and 2) to aid utilities in determining and understanding changes in CUBs associated with mercury control and a ssociated CUB management.

Under a 3-year effort funded by the U.S. Department of Energy (DOE) and industry entitled “Mercury and Air Toxic Element Impact s of Coal Combustion By-Product Disposal and Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of mercury and other air toxic elements on the ma nagement of CUBs. The EERC is measuring the release of mercury and other air toxic elements under different controlled laboratory conditions and investigating the release of these same air toxi c elements in select field settings. Results will be used to determine if mercury released fr om CUBs, both as curr ently produced and as produced with mercury and other emission cont rols in place, will im pact CUB management practices.

The EERC concluded Year 2 of this effort in April 2005, and this report details the results

to date from Task 2: An alytical Methods Selection. As noted in several forums in recent years, the

methods used to evaluate CUBs must be relevant to the material and th e management of CUBs where possible. EERC researchers reviewed me thods currently being used at the EERC and elsewhere to determine the best possible methods for this effort. A summar y of research in this area was published in 2004 (1).

BACKGROUND

Recent projections from the Energy Informati on Administration indicate that U.S. demand for energy will increase from 97.3 quadrillion to 130.1 quadrillion Btu between 2001 and 2020, reflecting an annual growth rate of 1.5%. By 2025, total energy consumption is projected to reach 139.1 quadrillion Btu (2). Fossil fuel co mbustion, including the burning of coal, natural gas, or oil, provides about 85% of the present energy production in the United States. Of this amount, over 50% is provided by coal -fired utilities (2). As a result of energy production from coal, CUBs are generated, and CU Bs, as produced in the United St ates, are primarily a result of emission control technologies instal led to meet emission regulations.

Emission regulations first mandated reductio n of particulate matter released to the atmosphere by utilities, which requi red utilities to install collection devices for generated fly ash. Later emission regulations significant to CUB production mandated limits on SO

x emissions. As2 a result, utilities using high-sulfur coal could change coal sources, resu lting in a different by-product character, or sc rub the flue gas using sorbents to remove the SO

x gases. The result of flue gas desulfurization (FGD) wa s high volumes of spent FGD sorbent material. There is a wide range of FGD technologies, so FGD materials have broadly varied characte ristics, but generally contain high concentrations of calcium and sulfur. Currently, utili ties are responding to regulation placing limits on NO

x emissions, which also impacts th e character of ash by-products, including potentially increasing the amount of unburned carbon in fly ash or adding ammonia to the fly ash. Issues related to air toxic emissions, including mercury, are cu rrently under technical and regulatory scrutiny.

Figure 1 includes an excerpt from a U.S. Environmental Protection Agency (EPA) Fact Sheet titled “EPA Proposes Optio ns for Significantly Reducing Mercury Emissions from Electric Utilities,” in which some of the concerns about mercury are summarized. On December 14, 2000, EPA announced that it would re gulate mercury emissions from coal- and oil-fired electric utility steam-generating power plants (3); propose regulations by December 15, 2003; and finalize regulations by December 15, 2004. On December 15, 2003, EPA signed the Utility Mercury Reductions proposal, which seeks comm ents on two approaches for reducing mercury by up to nearly 70%. On March 15, 2005, the EPA i ssued the first federal rule to permanently cap and reduce mercury emissions from coal-fired power plants (a power plant is defined as an electrical generating facility that provides >25 MW e ). The rule is a market-based cap-and-trade program (Section 111 of the Clean Air Act) and is similar to the pr ogram in place for SO 2 . The rule is to be administered in two phases. The first phase places a cap of 38 tons per year of mercury beginning in 2010. The second phase sets a final cap of 15 tons by 2018. Coal-fired power plants currently emit about 48 tons per year ; therefore, the reductio n in mercury emissions will be 21% and 69%, respectively.

Figure 1. Information from EPA on mercury emissions (4). Mercury Emissions – Both Naturally Occurring and Man-made Sources

• Mercury is a toxic, persistent pollutant that accumula tes in the food chain. Fossil fuel-fired utilities are the largest source of human-generated mercury emissions in the United States.

• Concentrations of mercury in the air are usually low and of little direct concern. However, atmospheric mercury falls to Earth through rain or snow and enters lakes, rivers, and estuaries. Once there, it can transform to its most toxic form, me thylmercury, and accumulate in fish and animal

tissues.

• Americans are exposed to mercury primarily by ea ting contaminated fish. Because the developing

fetus is the most sensitive to the toxic effects of mercury, women of child-bearing age are regarded as the population of greatest concern. Children who are exposed to low concentrations of methylmercury prenatally are at increased risk of poor performan ce on neurobehavioral tasks, such as those measuring attention, fine motor function, language skills , visual-spatial abilities, and verbal memory.

EXCERPTED FROM EPA FACT SHEET: EPA Proposes Options for Significantly Reducing Mercury Emissions from Electric Utilities December 15, 20033 The reduction of emissions at coal-fired pow er plants has historically impacted the quantity and character of resulting CUBs. The removal or reduction of mercury emissions at coal-fired power plants has high potential to do the same because several proposed mercury emission control technologies invol ve the use of solid sorbents th at will likely be introduced in the flue gas and collected with the fly ash. Ot her candidate emission control technologies focus on increasing the mercury sorbed on FGD ma terials. These mercury emission control technologies will impact the mercury content of CUBs. The question that this project was designed to answer is, “Will the changes in CUBs associated with mercury emission controls change the management options for those CUBs as they relate to the potential release of mercury?”

Since the large volumes of CUBs produced an nually in the United States are managed either by disposal or utilizati on, the design of various tasks in this project focused on simulating potential behavior of CUBs in environments where they are typically managed. Examples of

utilization scenarios include:

• The use of fly ash in concrete, soil stabilizati on, or fills that could be exposed to natural

waters or to microbial action.

• The use of FGD gypsum in wallboard, where it may be exposed to high temperatures in production or to natura l water under disposal.

• The use of fly ash in cement clinker production, where it would be exposed to extremely high temperatures.

• The use of FGD gypsum or fly ash as an agri cultural soil amendment or mine fill, where it would be exposed to natural wa ter and, potentially, microbial action.

In order to adequately address the potential for release of mercury from CUBs, sorbents, and combinations, release mechanisms that must be evaluated include leaching, elevated- and ambient-temperature vapor-phase releases, and microbiologically mediated releases. The EERC initiated research on the potenti al release of mercury from CUBs in 1999 and found that methods for evaluating the release of mercury from CUBs using these mechanisms were not documented in the scientific literature, with the exception of leaching. As a result, the EERC initiated a program under EPA’s Center for Air Toxic Metals ® and the Coal Ash Resources Research

Consortium ® to develop laboratory methods that woul d provide information on the potential for CUBs to release mercury and other air toxic elements under conditions associated with the proposed release mechanisms of di rect leaching, direct ambient- and elevated-temperature vaporphase release, and microbiologically mediat ed leaching and vapor-phase release.

OBJECTIVES

The goal of the methods selection task was to select or develop a ppropriate laboratory methods to evaluate the potential for release of mercury from CUBs under conditions that are relevant to management options applied to CUBs. Supporting objectives were as follows:4 $ Select and apply one or more leaching procedures appropriate for environmental

characterization of CUBs.

$ Select, develop, and apply a method to ev aluate the release of mercury through offgassing from CUBs at elevated temperatures.

$ Select, develop, and apply a method to ev aluate the release of mercury through offgassing from CUBs exposed to ambient temperature air.

$ Select, develop, and apply a method to eval uate the release of mercury through leaching and offgassing from CUBs exposed to biot a commonly found in natural settings.

$ Select and apply laborator y analytical methods require d to determine mercury in solutions, collected on analytical traps, and in solid materials.

METHODOLOGIES – ANALYTICAL AND CHARACTERIZATION METHODS

Chemical and Physical Characterization

Chemical characterization of samples included total mercury and total bulk chemical composition on major, minor, and trace constituen ts. Physical characterization included carbon forms, pH, moisture, and loss-on-ignition (LOI) m easurements. Eh measurements were taken on samples used for microbiological experiments. Methodologies used for these characterizations

are further described below.

Total Mercury

The total mercury content of solid samples was determined using a direct mercury analyzer or digestion followed by cold-vapor at omic absorption spectrometry (CVAAS).

Total Air Toxic Elements

The total concentration of the other air toxi c elements of arsenic, cadmium, chromium, lead, nickel, and selenium was determined usi ng standard methods. Acid digestion was used on the CUB followed by detection using inductively coupled atomic emission spectroscopy (ICP– AES) or ICP mass spectroscopy (ICP–MS).

Total Bulk Chemical Composition

The major bulk composition, reported as pe rcent oxides, was determined using x-ray fluorescence spectrometry. American Society fo r Testing and Materials (ASTM) D4326-04 Standard Test Method for Major and Minor Elements in Coal and Coke Ash by X-Ray Fluorescence was used (5).5 LOI and Moisture

Standard characterization tec hniques were used to measure LOI and moisture content. ASTM C311-04 Standard Test Methods for Samp ling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete was used (6).

pH

The pH of samples was determined using di stilled water and/or 1 M KCl. The method employing 1 M KCl is required for many types of solid samples that exhibit a double electric layer that impacts the determination of pH. For th is task, a slurry of 25 mL of 1 M KCl solution was mixed with 10 g of CUB, and the resulting pH was measured and recorded. As previously noted, the pH was also determined in slurry of distilled, dei onized water. Where both methods were employed in this effort, it was noted that th e pH values were similar. A comparison of these data for a relatively broad range of CUB types led researchers to conclude that it is not necessary to use 1 M KCl in determining the pH of CUB; therefore, remaining samples were evaluated using distilled, deionized water slur ries. It is likely that the high concentration of total dissolved solids generated in the pH determination eliminated the double electric-layer effect that requires

the use of KCl solution in the determination of pH in other type s of solid samples.

Carbon Forms

Dominant carbon forms were identified in a se lect group of project samples. The samples on which carbon forms were determined were pr epared by mounting them in epoxy resin. The sample was dispersed in the bottom of a 1- inch-diameter rubber cup mold. The epoxy was stained using Sudan black, which re sults in a high contrast between the particles of interest and the mounting medium. The surfaces to be analy zed were polished with incrementally smaller grits with 1⁄4 μm being the final polishing grit used. The samples were then examined using a reflected-light microscope.

Eh

Eh was determined using a platinum electr ode with a standard reference electrode.

Method Used to Measure Mercury on Gold-Coated Quartz Traps

Gold-coated quartz mercury collection traps we re desorbed for analysis by heating to approximately 500°C, and the mass of mercury released was determined using double-gold amalgamation with atomic fluorescence (AF) detection. A Brooks Rand Model III cold-vapor atomic fluorescence spectrophoto meter (CVAFS) was utilized for mercury concentration

determination.6 Method Used to Measure Mercury on Carbotraps

Supelco CarbotrapTM collection tr aps were analyzed for total mercury by heating them to approximately 300°C, passing the released organo mercury through a tube held at about 800°C, and collecting the mercury on a gold-coated quartz trap, which was analyzed as described above.

METHODS FOR THE EVALUATION OF THE RELEASE POTENTIAL OF

MERCURY AND OTHER AIR TOXIC ELEMENTS FROM CUB

Direct Leaching

Leaching is the most likely mechanism of tr ansport of constituents from disposed or utilized CUBs contacted by water. Leaching is typically performed on CUBs to characterize them for management purposes. The leaching tests performed on the samples in this project were the toxicity characteristic leaching procedure (TCLP [EPA Method 1311 (7)]), the synthetic groundwater leaching procedure (SGLP), and long- term leaching (LTL) w ith 30- and 60-day equilibration periods.

TCLP is a leaching procedure designed for th e evaluation of leaching of wastes when codisposed in a sanitary landfill. Leaching with TCLP utili zes a 20:1 liquid-to-solid ratio, endover-end agitation at approximately 30 rpm, an 18-hour equilibration time, and one of two

extraction fluids. The extraction fl uid used is dictated by the pH of the mate rial being leached. Extraction Fluid 1, used when the pH is below 5, is prepared by adding glacial acetic acid and sodium hydroxide to reagent wate r, and has a fluid pH of 4.93 ± 0.05. Extraction Fluid 2, used when the pH of the material is above 5, is prepar ed by adding glacial acetic acid to reagent water, resulting in a fluid pH of 2.88 ± 0.05.

The SGLP batch-leaching proce dure is a relatively simple test that follows many of the

conditions of TCLP. The test u tilizes a 20:1 liquid-to-solid ratio, end-over-end agitation at approximately 30 rpm, an 18-hour equilibration time, and usually employs a leaching solution consisting of water from the site, water that has b een prepared in the lab similar to water likely to contact the CUB, or distilled deionized water. When distilled water is used as the leaching solution for SGLP, the method is equivalent to the ASTM D3987 Standard Test Method for Shake Extraction of Solid Waste with Water (8). Distilled deionized wa ter was used in this effort. For the long-term component of this proce dure, multiple bottles are set up and analyzed at

different time intervals. A typical SGLP–LTL test might cons ist of 18-hour, 30-day, and 60-day equilibration times. Although 60 days is often not adequate to achieve complete equilibrium, it is generally long enough to determine the concentrat ion evolution of individual parameters. The most important factor when performing LTL is to have at least three equilibration times to

determine a true trend. A draft of the SGLP–LTL method prepared for consideration by ASTM is in Appendix A.

For all leaching procedures, the solids were filtered from the leaching solution through a 0.45-μm filter, the pH of the resulting leachate was measured, and the leachate was preserved with HCl for mercury determination and with HNO 3 for determination of other trace elements.7 Mercury leachate concentrations were determined using CVAA S and CVAFS as noted in the analytical methods section. Othe r trace elements were determined using inductively coupled argon-plasma spectrometry, ICP–MS, or gra phite furnace atomic absorption spectroscopy.

The SGLP method was used preferentially fo r the project samples, and where TCLP was applied, SGLP was also applied. TCLP was incl uded because some regulatory groups continue

to use TCLP results to determine whether a “was te” is hazardous. The SGLP short-term leaching procedure was applied to all samples, but for samples with a pH >10, the LTL option was also used. CUBs exhibiting a high pH have the poten tial to undergo hydrati on reactions that can change the leaching profile with time. The EERC documented the impact of ettringite formation

on leachate concentrations of several elements that are frequently present in CUBs such as selenium and boron (9–12). The elements that are most likely to be incorporated into the ettringite structure and exhibit a change in leaching profile with tim e are those that are present as oxyanions at high pH. Examples of leaching profiles of high pH CUBs for some trace constituents commonly found in CUBs are shown in Figures 2 and 3.

Figure 2. Long-term leaching results for boron

.8 Figure 3. Indirect evidence of e ttringite formation using SGLP and LTL (note: boron is on a secondary axis ).

Vapor-Phase Transport

Long-Term Ambient Temperature Release

In order to develop a method to evaluate the potential for rele ase of mercury from CUBs at ambient temperatures, several preliminary deci sions were made based on the practicality of performing this type of evaluati on in the laboratory, as follows:

• In order to measure mercury releases fr om CUBs, most of which have very low concentrations of mercury, sa mples with relatively high concentrations of mercury

would be evaluated first.

• In order to evaluate multiple samples with available equipment and instrumentation, released mercury would be collected on analytical gold-coated quartz traps.

• Because very low release of mercury was anticipated, it was decided to expose a column of CUB to low-mercury air rather th an expose only the surface of a CUB to the ambient temperature low-mercury air.

Using these preliminary premises, 250-mL wide -mouth glass test cont ainers were designed with bonded Teflon liner caps. Two holes were dr illed in the caps to accommodate a silicone tube for gas inlet and a Teflon outlet bulkhead fitting. The gas in let tube extended nearly to the

bottom of the container while the outlet tube extended only s lightly into the container.9 Using these test containers, approximately 150-g aliquots of CUB provided a column of material through which the low-mercury air coul d be transported. Breathi ng-quality air from a cylinder was passed through several sets of gold-coated quartz traps for mercury removal and admitted to each of the bottles through a gas dist ribution manifold that routed the gas through 0.25-mm-ID gas chromatography (GC) capillary t ubing to each of the individual bottles. The pressure drop across the GC cap illary tubing allowed for the re gulation of air flow through each bottle by simply adjusting the length of tubing to each bottle. The length of tubing was a nominal 65 cm. This length of tubing, when pressuri zed to between 1 and 2 psig through a gas distribution manifold, provided a convenient means of regulati ng gas flow to approximately

2 cm 3 /min. Because of the variability of particle sizes between diffe rent ash samples, the sample with the initial highest gas flow was left with a 65-cm length of GC tubing, and other samples had their tubing lengths shortened until all samples had approximately the same flow rate. The air exiting the GC tubing was given a final scrubbing to rem ove mercury vapor using a goldcoated quartz trap just prior to entering the bottle containing the CUB. After entering the bottles, the air passed through the ash a nd exited to a central mercury collection tube containing two separate gold-coated quartz traps. The second ou tlet or top trap was used to prevent mercury contamination from atmospheric mercury. Th is setup is illustrated in Figure 4.

The gold-coated quartz trap nearest the exit bulkhead fitting was analyzed multiple times with the most typical sampling scheme being one 7-day period followed by two consecutive 90- day periods. The gold-coated quartz analytical traps were evaluated according to the method described in the analytical met hod section. In or der to determine the tota l mercury released over the duration of the experiment, th e mercury results from all experimental time segments needs to be combined, and the containe r blank needs to be subtract ed. The container blank was determined on the empty bottles used to hold the samples.

Figure 4. Mercury vapor rele ase collection apparatus.10 Examples of replicate data from a vari ety of CUB samples are shown in Figure 5.

Figure 5. Average total long-term ambient-temperat ure mercury release or sorption as related to blank values, pg/g/day. Positive values indicate re lease and negative values indicate sorption of

mercury.

Vapor-Phase Transport

Thermal Desorption at Elevated Temperature

Since mercury and mercury compounds are high ly volatile, mercury was expected to be released from CUBs when they were exposed to elevated temper atures. Even mercury that is sorbed on fly ash, FGD material , or sorbents developed to re move mercury in flue gas is expected to have high potentia l to be released if exposed to high enough temperatures. Instrumental and equipment constr aints existed for the physical te sting of elevated temperature release of mercury from CUBs. Thes e constraints included the following:

• Furnaces available for the experimental apparatus could only achieve maximum temperatures of 750°C.

• Fittings and connecting tubing needed to be heated in order to minimize the loss of mercury in the system.

• Gas flow to remove the mercury from the h eated sample cell to the analytical cell

needed to be constant.

• Temperature ramping needed to be controll ed and consistent between sample runs.11 The apparatus was constructed as shown in Figure 6. The CUB sample was weighed into a quartz tube with quartz wool used to keep the sample in place in the tube. Nominal sample size was approximately 1 g. The sample tube was placed into a small tube furnace capable of achieving a maximum of 750°C. A programmed temp erature controller ramped the furnace from ambient to maximum temperature at 25°C per minut e. In preliminary experiments, the maximum temperature achievable was 700°C, but an improve d furnace was incorporated into the apparatus

to increase the maximum to 750°C. A nitrogen gas flow of 5 cm 3 /min was introduced into the tube furnace. As the mercury and mercury com pounds desorbed from the CUB in the sample tube, the nitrogen flow carried them though the syst em to the electrically heated quartz analytical cell. The quartz analytical cell was operate d at 800°C, allowing the detection of mercury compounds by thermally decomposing compounds to form elemental mercury, which can be detected by atomic absorption (AA). The analytical cell at the top of the diagram was placed in the center-focused beam path of an AA spect rophotometer (AAS). A mercury hollow cathode lamp was used as the light source, and the AAS detector was set to the 253.7 nm line for mercury. A Hewlett Packard 3395 integrator was used for data collection.

Examples of thermal desorption curves genera ted with this method ar e shown in Figures 7

and 8.

Figure 6. Mercury thermal desorption apparatus.12 Figure 7. Typical thermal de sorption curve for fly ash.

Figure 8. Example of thermal desorp tion curve for an FGD material.13 Microbiologically Mediated Leaching and Vapor-Phase Transport

The EERC review of published data on the releas e of mercury from CUBs (1) reported that the only published method demonstrated for use in evaluating the release of mercury from CUBs on exposure to natural biota was developed by the EERC. The EERC method has been under development since approximately 1999 and has undergone numerous modi fications to achieve the goal of evaluating the mercur y release potential by leaching and offgassing when CUBs are under microbiologically mediated conditions. Th e first experiments performed using early versions of the apparatus focused on mercury releases by offgassing.

The first apparatus assembled to conduct micr obiologically mediated vapor-phase mercury release used a 250-mL Erlenmeyer flask fitted with an impinger inlet/outle t tube with the inlet center shortened to 6 cm below the standard tape r. Cylinder gas was passed through several sets of gold-coated quartz traps for mercury removal and admitted to each of the flasks through a gas distribution manifold that routed the gas th rough 0.25-mm GC capillary tubing to each of the individual flasks. A GC capillary length of a pproximately 60 cm, when pressurized to between 1 and 2 psig through a gas distribution manifold , provided a convenient m eans of regulating gas flow to approximately 2 cm 3 /min. The gas passed mercury vapor from the head space of the flasks to a mercury vapor collection system at th e outlet of the fl asks, consisting of two traps. The nearest trap contained Supelco Carbotra pTM, which collected organomercury compounds, followed by a gold-coated quartz trap, which collected elemental mercury.

The flasks were placed on a 16-flask wrist- action shaker. The experimental matrix consisted of eight flasks under an aerobic conditions (using argon) and eight flasks under aerobic conditions (using breathing-quality air). In each se t of eight flasks, two contained only buffer, three contained the CUB with buffer (starved), and three contained the CUB with buffer and glucose (fed). An 80-g aliquot of CUB was pl aced in the flasks, and 100 mL of a phosphate buffer (with or without glucose as appropriate) was added to create a neutral pH. The CUBcontaining flasks also had 100 μL of mixed bacterial culture adde d. The source of bacteria was a

mixed bacterial inoculum from a brackish wetl and. This setup is illu strated in Figure 9.

This apparatus underwent several iterations as difficulties were identified and solved. The

wrist-action shaker was abandoned because it was unable to provide adequate suspended sample.

Instead of the wrist-action shak er, a 9-place stir plate was introduced. This was operated for about 20 minutes every 3 hours to maintain sa mple agitation over the 30-day period of the experiment. Additionally, the samp le size was reduced to 20 g, and the buffer was increased to 150 mL to provide adequate sample volume for additional trace element analyses. The buffer composition was also altered. It was found that phosphate and nitrate interfered with a derivitization step in the determination of organomercury compounds in the solid-phase microextraction (SPME) determination using GC separation followed by detection of the mercury compounds by atomic fluorescence. This technique is described later. The original

buffer utilized nominal concentr ations of phosphate and nitrate salts. The improved buffer used only 100 ppm of phosphate and substituted potassium glutamate as the nitrogen source. This simple change appeared to remove the interf erences. Additionally, later experiments did not involve the use of starved control samples. In current experiments, all samples are fed with glucose. This setup is illustrated in Figure 10.14 Figure 9. Microbiologically mediated mercury vapor-phase collecti on apparatus utilizing a wrist action shaker to facilitate mixing.

Figure 10. Microbiologically mediated mercury va por-phase collection appa ratus utilizing a stir plate to facilitate mixing.15 Analyses of mercury and air toxic element re leases were performed after a 30-day period. The gold-coated quartz traps and CarbotrapsTM were analyzed as described in the analytical methods selection. Total mercury concentrations of the leachate were determined using CVAFS. Total air toxic element concentrations were determined using ICP–AES or ICP–MS.

Bacterial counts were performed upon completi on of the experiment. A 1-mL aliquot of solution was taken from each flask. The aqueous s upernate was serially diluted in 0.1% sodium pyrophosphate buffer (pH 7) and then used to inoc ulate a series of tubes containing 1% PTYG (peptone, tryptone, yeast extract, glucose) broth. The tubes were incuba ted at 30°C and growth, as turbidity, was monitore d over a 3-week period.

SPME was used in the determination of organom ercury species in the liquid portions of the samples. SPME is a sample collection technique in our case utilizing a fiber coated with polydimethylsiloxane. Samples containing orga nomercury compounds are first derivatized to increase the volatility of or ganomercury halides such as methylmercuric chloride. The derivitization reagents used were sodium tetraethyl borate, sodium tetrapropyl borate, and sodium tetraphenyl borate. Sodium tetraet hyl borate was most commonly used. In the derivitization procedur e, derivatizing agent, acetate buffer, an internal standard (usually propyl mercuric chloride), and sample were mixed in a septum-capped vial. In a relatively fast reaction, the halide is replaced with the appropriate alkyl or aryl group, dependi ng on which derivatizing agent is chosen. A SPME fiber was inserted through the septum cap, and the sample was stirred using a Teflon-coated stir bar for 20 minutes. Af ter this equilibration time, the SPME fiber was

introduced into the heated inlet zone of a GC . Sample separation can be accomplished using a 0.53-mm capillary column 15 or 30 meters in le ngth. The exit end of the column was connected to a heated (800°C) quartz tube, and makeup heli um gas was added to increase the total flow to 25–30 mL per minute. The gas was then routed to an AF detector for determination of the separated mercury compounds. An example of a SPME chromatogram generated with this method is shown in Figure 11.

Figure 11. Example of a SPME chromatogram.16 SUMMARY

Analytical methods were selected based on project needs and the sample types requiring analysis. Standard analytical met hods were selected and used as fr equently as possible. Replicate analyses were performed on a regular basis as pa rt of the laboratory quality assurance/quality control program.

The leaching method selected, the SGLP–LTL , was selected based on EERC experience and familiarity with a large number of leaching procedures used to characterize CUBs and the appropriate application of those tests. The SG LP–LTL meets the criteria that EERC researchers have identified for leaching procedures to provide scientifically valid information. These criteria

are as follows:

• Reactivity or other properties of the mate rial being leached that may influence the leaching profile.

• The setting where the material is to be placed and the water that will most likely contact that material in that setting.

• The leaching time required to allow adequate time for hydration reactions to occur in reactive materials, such as high calcium coal fly ash.

The elevated-temperature vapor-phase re lease method underwent minor modifications early in the project but has been shown to provide reprodu cible data. The remaining technical challenge with the method as employed for this pr oject is the limitations associated with the maximum achievable temperature to be applied to the CUB under investigation; and this cannot be addressed under this project.

The ambient-temperature vapor-phase release me thod developed for this work also presents technical challenges, but they are related to the quantitation limitations for mercury. The extremely low levels of mercury released at ambi ent temperatures are frequently near the levels of detection for the analytical system being us ed. The physical nature of the CUB samples also

results in variable data and the need to modify the method. As an example, using the apparatus to evaluate the potential for releas e of mercury from a wet FGD ma terial required modification of the apparatus to shorten the gas inlet tube to ab ove the level of the sample because gas could not be forced through the material when the inlet was near the bottom of the sample container.

The method developed to ev aluate the microbiologically me diated release of mercury underwent a relatively high degree of modification method over the first 2 years of the project. The final apparatus description and method now meets the project goals to produce reliable and relatively reproducible vapor and leachate samples. An evaluation of the particle-size reduction associated with the use of magnetic stir bars in the reaction vessels will be performed, and results

of that evaluation will be included in future project reports.17 REFERENCES

1. Hassett, D.J.; Pflughoeft-Hassett, D.F.; Heebink, L.V. A Review of the Current State of the Science Related to Rerelease of Me rcury from Coal Combustion Products ; Final report for Utility Solid Waste Activ ities Group; EERC Publication 2004-EERC-11-01; Energy &

Environmental Research Center : Grand Forks, ND, Nov 2004.

2. Energy Information Administration. Annual Energy Outlook 2004 with Projections to 2025 ; U.S. Department of Energy: Washington, DC, 2004.

3. Regulatory Finding on the Emissions of Hazar dous Air Pollutants from Electric Utility Steam Generating Units. Fed. Regist

. 2000

, 65 (245), 79825–79831.

4. U.S. Environmental Protection Agency. Fact Sh eet “EPA Proposes Options for Significantly Reducing Mercury Emissions from Electric Utilitie s,” Dec 15, 2003.

5. American Society for Testing and Materials. Standard Test Method for Major and Minor Elements in Coal and Coke Ash By X-Ray Fluorescence. D4326-04.

6. American Society for Testing and Materials. Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete. C311-04.

7. U.S. Environmental Protection Agency; Test Methods for Evaluating Solid Waste: Physical/Chemical Methods (SW-846) , Method 1311, Toxicity Characteristic Leaching

Procedure. 1992.

8. American Society for Testing and Materials. Standard Test Method for Shake Extraction of

Solid Waste with Water. In Annual Book of ASTM Standards ; Section 11: Water and

Environmental Techno logy, ASTM D3987-85, 2004.

9. Hassett, D.J.; McCarthy, G.J.; Henke, K.R.; Korynt a, E.D. Characteriza tion of a Lignite Ash

from the METC Gasifier III: Correlations with Leaching Behavior and Mineralogy. In Fly Ash and Coal Conversion By-Products: Characterization, Utilization, and Disposal I. ; McCarthy G.J.; Lauf, R.J., Eds.; Material s Research Society: Pittsburgh, PA, 1985.

10. Hassett, D.J.; Pflughoeft-Hassett , D.F.; McCarthy, G.J. Ettring ite Formation in Coal Ash as

a Mechanism for Stabilization of Hazardous Trace Elements. In Stabilization and Aquatic
Uses, Proceedings of the 9th International Ash Use Symp osium; Orlando, FL, Jan 22–25, 1991; EPRI Report GS-7162, Proj ect 3176, 1991; Vol. 2, pp 31-1–31-17.

11. Hassett, D.J., Thompson, J.S. Ettringite Formation as a Fixation Technology for Immobilizing Trace Elements ; Final Report to GRI GRI-96/0322. Feb 1997, 41

12. McCarthy, G.J.; Hassett, D.J.; Bender, J.A. Sy nthesis, Crystal Chemistry and Stability of Ettringite, a Material with Potential Appli cations in Hazardous Wa ste Immobilization. In Proceedings of the Materials Research Society Symposium; 1992; Vol. 245.

# APPENDIX A

DRAFT ASTM STANDARD METHOD FOR

SYNTHETIC GROUNDWATER LEACHING

PROCEDUREDRAFT

1 DRAFT ASTM STANDARD METHOD FOR

SYNTHETIC GROUNDWATER LEACHING PROCEDURE

1. Scope

1.1 This method determines the leachability of constituents in wastes, products, or materials using a leaching solution designed to simulate leachate anticipated in field conditions. The method allows for prediction of changes in leachability brought about as a result of the formation of secondary hydrated phases and new minerals through interaction of the waste and water over extended periods of time.

1.2 his method consists of the agitation of waste and a synthetic groundwater solution over an extended period of time (greater than 60 days) with sampling at regular intervals.

1.3 This method allows a comparison of maximum leachate concentration with actual concentrations of leachate at time intervals of from 18 hours to 2 months or greater. The method allows for determination of mass of analyte mobilized based on a leachate concentration and percent of total element leached and provides information to estimate leachate concentration trends with respect to time.

1.4 This method may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of whoever uses this method to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

2. Applicable Documents

2.1 American Society for Testing and Materials (ASTM) Standards: D1129 Definitions of Terms Relating to Water D1193 Specification for Reagent Water

D3987 Shake Extraction of Solid Waste with Water D2216 Method for Laboratory Determination of Moisture Content of Soils

2.2Toxicity Characteristic Leaching Procedure (TCLP) EPA Method 1311

3. Definitions

3.1 For definitions of terms in this test method, see Definitions D1129.

3.2 Ettringite: Ettringite is a mineral having the nominal composition Ca 6 Al 2 (SO 4 ) 3 (OH) 12 ·26H 2 O. Ettringite is also the family name for a series of related compounds as is the case for many mineral families. Ettringite has characteristic structural features that are fairly unique. The structure comprises of calcium aluminate columns {Ca 6 Al 2 (OH) 12 24H 2 O} 6+ with the channels between these columns containing the other components, which include an oxyanion such as sulfate with hydroxide and water {(SO 4 ) 2-4 (OH) 0-4 (H 2 O) 0-6 } 6- . Ettringite is unique in that several elements that exist as oxyanions can substitute for the sulfate in th e structure. These elements include but are not limited to arsenic, boron, chromium, molybdenum, selenium, and vanadium. Ettringite is known to form in the hydration of low-rank coal conversion solid residuesDRAFT

2 (CCSRs) and in CCSRs from advanced coal combustion processes such as fluidized-bed combustion (FBC) and limestone injection modified burner (LIMB).

3.3 Synthetic Groundwater: Synthetic groundwater as used in this application refers to a solution prepared in the laboratory containing the major geochemical parameters that would be found in water likely to contact the disposed CCSR. In the case of rainwater contact, this solution would be Type IV water, while with groundwater, a typical solution might contain calcium, magnesium, sodium, sulfate, and bicarbonate. Groundwater collected at the site of disposal could also be used, although if that were the case, corrections would have to be made for concentrations of trace elements already present in the water. It has been found with most CCSRs that it is the CCSR that regulates the equilibrium concentrations of major constituents in a synthetic groundwater leaching procedure; thus the inclusion of major geochemical constituents of actual groundwater may be unnecessary in many cases.

4. Significance and Use

4.1 This test is intended as a means for determining the mass of analyte readily mobilized by leaching with groundwater and also provides a means of determining the trend of leachate concentration change, if applicable. This test is intended for use with CCSRs

and other materials formed under conditions of high temperature. The long-term nature

of the test allows the determination of cha nges in concentrations of leached constituents as materials react with water to form secondary hydrated phases and other materials not present in the original material.

4.2 This test method is not intended to provide an accurate means of determining actual leachate concentrations under field conditions. The test does provide information about leaching under field conditions, however, and is useful in predicting the mobility of leachable constituents of CCSRs. The information provided from this test is an estimation of the mass of analyte that can be solubilized and trend of concentration change with respect to time. It should be noted that not all analytes will increase in concentration to an equilibrium level. Numerous elements, especially those trace elements that exist as oxyanions in aqueous solution, can exhibit a decrease in solution concentration after an initial and normally rapid increase in concentration. Additionally, major constituents can change solution concentration in a manner that would not be predicted on the basis of solubility calculations based on common mineral types, especially in CCSRs that form ettringite.

4.3 Since CCSRs are produced under conditions of high temperature, reactions with water during leaching can be expected. If these reactions produce ettringite, the concentrations of analytes present in solution as oxyanions can be expected to decrease with respect to time as ettringite forms. Other mineral formation can be expected to control leachate concentrations of additional analytes in ways not expected from simple solubility calculations based on the composition of ash before leaching. Additionally, the formation of secondary hydrated phases can be expected to affect the concentrations of major components.DRAFT

3 5. Apparatus

5.1 For a complete description of the apparatus, see ASTM Standard Test Method for ShakeExtraction of Solid Waste with Water. Any apparatus that can provide conditions of endover-end agitation at 30 plus or minus 2 rpm as specified in the protocol for the TCLP can be used in this procedure.

6. Reagents

6.1 Purity of Reagents – Reagent-grade chemicals can be used, provided they do not contain appreciable amounts of elements to be determined in the extraction test. Reagents must be of sufficient purity so they do not interfere with the accuracy of the test or introduce bias in the results of analyses of leachates.

6.2 Purity of Water – Unless otherwise indicated, references to water shall be understood to mean Type IV reagent water at 18° to 27°C (Specification D1193). The method by which the Type IV water is prepared (distillation, ion exchange, reverse osmosis, etc.) should remain constant throughout the test.

6.3 Synthetic Groundwater – Synthetic groundwater is a leaching solution containing the major geochemical parameters important to groundwater likely to contact disposed CCSRs. As previously stated, in the case of CCSRs disposed above the water table and where the likely water to contact the disposed materials is rainwater, Type IV water can be used as the leaching solution. Where the water likely to contact disposed material is highly mineralized, either a sample of the water itself or a synthetic mixture prepared in the lab will be used. A typical North Dakota synthetic groundwater can be prepared by dissolving 0.50 grams of sodium sulfate and 1.00 grams of sodium bicarbonate in one liter of Type IV water. The analysis of this solution is as follows:

Na 436 mg/L

SO 4 338 mg/L

HCO 3 726 mg/L pH 8.3–8.7

This sodium sulfate bicarbonate buffered water is typical for central and western North Dakota. Used for leaching low-rank coal ash, calcium was omitted since the ash itself ultimately

determined the final calcium concentration.DRAFT

4 Other formulas for synthetic groundwater can be prepared as needed for site-specific conditions. Care is required when preparing fo rmulations containing calcium and magnesium that carbonates not be allowed to precipitate. This can be overcome by adding the reagents in the proper order, being certain that all carbonate is buffered to bicarbonate before adding the calcium and magnesium. Since sulfuric acid is used for sulfate and acid buffering, having excess sulfuric acid acidity will ensure this. A lo tus spreadsheet is available for the calculations necessary to select reagents for synthetic groundwater formulations, but with the limited components, the calculations can also be easily carried out manually.

7. Sampling

8. Sample Preparation

8.1 For sample preparation, see D3987 Standard Test Method for Shake Extraction of Solid

Waste with Water.

9. Procedure

The laboratory protocol is similar to the U.S. Environmental Protection Agency (EPA) TCLP

and ASTM D3987 Standard Test Method for Shake Extraction of Solid Waste with Water. The primary difference is in the selection and preparation of the extraction fluid and the extension of test equilibration time over the prescribed 18-hour period. The long-term leaching aspect of this test is especially important since CCSRs can form secondary hydrated phases upon contact with water that can have a profound impact on leachate concentration of trace elements, especially elements that tend to exist as oxyanions in solution. The formation of secondary hydrated phases is known to take time, depending on the source of reactants in the leaching system. Time for complete formation of secondary hydrated phases can be from days to months. The test is not intended to carry the leaching to complete equilibrium but rather to extend the leaching time long enough for prediction of leachate concentration trends. For specifics related to the test, see D3987 Standard Test Method for Shake Extraction of Solid Waste with Water, or EPA Method 1311 TCLP, Federal Register, Vol 55, No. 126, June 29, 1990.

9.1 Record the physical description of the sample to be tested including particle size as

known.

9.2 Solids Content – Determine the solids content of the sample as described in D3987 Standard Test Method for Shake Extraction of Solid Waste with Water, Sections 9.2.1 through 9.2.4.

9.3 Shake Procedure – Prepare the apparatus and begin the test as described in D3987 Standard Test Method for Shake Extraction of Solid Waste with Water, Sections 9.4 through 9.7, except that multiple shake test containers are prepared for each sample, the number depending on the duration of long-term leaching. Leaching solution shall be prepared as described in the following section. Long-term leaching intervals for this procedure are 18 hours, 1 week, 1 month, and 2 months. Longer times can be used ifdesired, although trends are usually identified within the 60-day duration of this longterm leaching procedure. An alternative to the use of 2 liters of leaching solution involves the use of 225-mL polysulfone bottles. To each bottle, 10 grams (dry weight) of ash is added along with 200 mL of leaching solution. Multiple bottles prepared in thisDRAFT

5 manner provide at least 150 mL of leachate and allow for the simultaneous extraction of a large number of samples with minimal space and equipment. It has been found that the standard equipment used for TCLP leaching will generally hold four of the polysulfone containers in the same position usually reserved for one 2-liter container.

9.4 Preparation of Leaching Solution: Leaching solution shall be prepared as recommended by an evaluation of field conditions. Where material disposed in a monofill is above the water table, the leaching solution shall be Type IV water (D1193 Specification for Reagent Water). Where the disposed material will likely be contacted by groundwater, either a sample of groundwater from the site or a synthetic groundwater shall be used for leaching. The synthetic groundwater if prepared in the lab shall contain all of the primary mineralization parameters as determined from an analysis of groundwater from the site or from an evaluation of data from analysis reports of water representative of the area of disposal.

9.5 Long-Term Leaching Sampling

B Long-term samples are taken from containers prepared for the shake test in an identical manner to the specimen for the 18-hour sampling period. These containers are sampled at the end of 1 week, 1 month, and 2 months. Longer sampling intervals can be added as required. A convenient method for doing this procedure is to prepare the samples at time intervals so that all of the samples are finished at the same time. For example, one sample is prepared, a second is prepared 1 month later, a third sample 1 month later, and a final sample 18 hours before the other samples are due to be terminated. This saves considerable lab time and expedites the entire procedure.

9.6 Sampling of Leachate

B Leachate is sampled for analysis as specified in D3987 Standard Test Method for Shake Extraction of Solid Waste with Water, Section 9.8.

9.7 Analysis

9.7.1 Selection of Analytes to Be Included in the Report. Analytes include all elements present in the ash in high enough concentrations to be problematic in disposal. These can be determined through screening procedures such as proton-induced x-ray emission (PIXE), instrumental neutron activation analysis (INAA), or plasma emission such as inductively coupled argon plasma (ICAP) spectroscopy or ICAP–mass spectrometry. Analytes for ash screening generally include the eight Resource Conservation and Recovery Act (RCRA) elements for regulatory

purposes.

9.7.2 Determination of Total Concentration of Select Analytes. Analytes selected on the basis of screening (9.6.1) are determined on a bulk sample prepared by digestion of sample in a microwave heated-sealed Teflon bomb. Analyses can be performed according to methods for trace analyses in SW846.

9.7.3 Determination of Analyte Concentrations in Leachates. Concentrations of analytes in leachates shall be determined using methods as described in SW846 or by approved analytical techniques us ing EPA or other approved techniques.DRAFT

6 All data shall be validated using good laboratory practice and approved quality assurance/quality control (QA/QC) procedures.

10. Calculation

10.1 Calculate the solids content as specified in D3987 Standard Test Method for Shake Extraction of Solid Waste with Water, Section 10.1.

10.2 Calculation of maximum analyte concentration is determined by dividing the total mass of analyte in a sample by the volume of liquid used for leaching. C = M/V where C = Concentration of analyte M = Mass of sample leached V = Volume of leaching solution used

For this procedure the M:V ratio should be 1:20 as specified in the leaching protocol.

11. Report

11.1 The report shall include the following:

11.1.1 Source of CCSR, date of sampling, a nd preservation method used for leachates. 11.1.2 Description of CCSR including coal source, combustion technique, and method of sample collection (electrostatic precipitator, baghouse, etc.) 11.1.3 Solids content (see Method D2216) 11.1.4 A table of maximum analyte concentrations as determined by the method described in Section 10.2. (bulk chemical analysis) 11.1.5 A table of analyte concentrations as determined from analysis of 18-hour, 1- week, 1-month, 2-month, and any additional extended time intervals selected.

12. Precision and Bias

12.1 No information is presently available on the precision and accuracy or bias of this standard practice. It is recommended that standard QA/QC procedures such as analysis of duplicate samples and spiking of analyte be used for verification.

12.2 The precision of this test will vary depending on the material being leached.

# APPENDIX E

SAMPLE PRIORITIZATIONWorking Document Revised April 20, 2003

1 

## Mercury and Air Toxic Element Impacts of Coal Combustion Byproduct Disposal and Utilization

Sample Selection Criteria EERC Priority Justification (H=high; M=medium; L=low)

FUEL TYPES

• Bituminous H commonly used

• Subbituminous H commonly used

• Lignite H commonly used but generally higher mercury

content

• Oil H Industry sponsor priority

• Bituminous–Subbituminous Blends H M limited use

• Subbituminous–Lignite Blends L Only very limited use

BURNER TYPES

• pc fired H Most common

• Cyclone M Limited installations

• Stoker L Limited installations

• FBC L Limited utility installations

PARTICULATE COLLECTION

• Fabric Filter H commonly used

• ESP Cold Side H Most common

• ESP Hot Side M Less common

• ESP/Mechanical L Limited installations

• FF/Mechanical L Limited installations

SO 2 CONTROL

• None H Most common

• Wet FGD (calcium based) H Commonly used (include lime & limestone sorbents; fo rced oxidation & natural or in situ oxidation systems.)

• Dry FGD (calcium based) M Less common

• Spray Dryer Atomizer (SDA) H Commonly used with potential for additional installations

• Wet FGD (alkali based) L Limited installations

• Dry FGD (alkali based) L Limited installations

AMMONIA-BASED SYSTEMS

• None H Most common

• Ammonia Injection H Commonly used

• SCR H Commonly used

• SNCR H L Limited installationsWorking Document Revised April 20, 2003

2 

## Mercury and Air Toxic Element Impacts of Coal Combustion Byproduct Disposal a nd Utilization (continued)

Sample Selection Criteria EERC Priority Justification (H=high; M=medium; L=low)

PROPOSED Hg CONTROL

• Carbon Injection H Predicted for high use

• Noncarbon Sorbent Injection H Good potential for limited impact to ash quality

• Modified FGD H Expected to concentrate mercury on FGD material and limit impact to fly ash quality

• Fine Particulate Control H Good potential for limited impact to ash quality

• Fly ash from carbon removal technologi es H High interest to sponsors

# APPENDIX F

SAMPLE IDENTIFICATION NUMBER AND

DESCRIPTIONSID No.CollectionDate Sample Type Sample Type Notes Sample Treatment Coal Type Coal NotesBurnerTypeParticulateCollectionParticulate CollectionDescription Collection Point99-188 2/9/1999 FGD-SDA PRB Subbituminous pc-fired FF Silo00-048 10/12/2000 FGD-SDA Fort Union Lignite Cyclone FF01-002 2/26/2001 Fly Ash Eastern Bituminous pc-fired ESP Cold-side01-008 4/5/2001 Fly Ash PRB Subbituminous pc-fired ESP Hot-side01-011 5/9/2001 FGD-SDA Fort Union Lignite Cyclone FF02-002 4/25/2001 Fly Ash + Activated Carbon Eastern Bituminous Low S washed pc-fired COHPACESP-HS & COHPACFF FF02-003 4/26/2001 Fly Ash + Activated Carbon Eastern Bituminous Low S washed pc-fired COHPACESP-HS & COHPACFF FF02-004 11/14/2001 Fly Ash + Activated Carbon PRB Subbituminous pc-fired ESP Cold-side ESP Field02-005 11/14/2001 Fly Ash + Activated Carbon PRB Subbituminous pc-fired ESP Cold-side ESP Field02-006 11/14/2001 Fly Ash + Activated Carbon PRB Subbituminous pc-fired ESP Cold-side ESP Field02-007 4/25/2001 Fly Ash + Activated Carbon Eastern Bituminous Low S washed pc-fired COHPACESP-HS & COHPACFF FF02-069 7/18/2002 Fly Ash + Activated Carbon Eastern Bituminous Low S pc-fired ESP Cold-side ESP Row02-070 7/18/2002 Fly Ash Eastern Bituminous Low S pc-fired ESP Cold-side ESP Field02-071 7/22/2002 Fly Ash + Activated Carbon Eastern Bituminous Low S pc-fired ESP Cold-side ESP Field02-072 7/22/2002 Fly Ash Eastern Bituminous Low S pc-fired ESP Cold-side ESP Field02-073 7/6/2002 Fly Ash Eastern Bituminous Low S pc-fired ESP Cold-side ESP Field02-074 7/6/2002 Fly Ash Eastern Bituminous Low S pc-fired ESP Cold-side ESP Field02-076 9/24/2002 Fly AshSouth AmericanBituminous Low S pc-fired ESP Cold-side ESP Row03-004 Fly Ash Eastern Bituminous KY & WV; Low S pc-fired ESP Cold-side ESP Field03-005 Fly Ash Eastern Bituminous KY & WV; Low S pc-fired ESP Cold-side ESP Field03-006 Fly Ash Eastern Bituminous KY & WV; Low S pc-fired ESP Cold-side ESP Field03-007 Fly Ash Eastern Bituminous KY & WV; Low S pc-fired ESP Cold-side ESP Field03-008 11/19/2002 Fly AshSouth AmericanBituminous Low S pc-fired ESP Cold-side ESP Row03-009 11/20/2002 Fly Ash + Activated CarbonSouth AmericanBituminous Low S pc-fired ESP Cold-side ESP Row03-010 11/22/2002 Fly Ash + Activated CarbonSouth AmericanBituminous Low S pc-fired ESP Cold-side ESP Row03-016 6/10/2003 Fly Ash Fort Union Lignite pc-fired ESP Cold-side ESP Field03-017 6/10/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fired ESP Cold-side ESP Field03-018 6/10/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fired ESP Cold-side ESP Field03-019 6/10/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fired ESP Cold-side ESP Field03-060 5/21/2003 Fly Ash + Activated Carbon PRB SubbituminousBelle Ayr coal; 6109tons/day coal + 94 tons/daywaste seed corn: 98.5%coal/1.5% biomass CycloneAdvancedHybrid Advanced Hybrid03-061 5/10/2003 Fly Ash PRB Subbituminous 6400 tons/day coal CycloneAdvancedHybrid Advanced Hybrid03-062 6/10/2003 Fly Ash + Activated Carbonlab composite of 03-017 –03-019 (80/10/10 wt%) Fort Union Lignite pc-fired ESP Cold-side ESP FieldPage 1 of 8ID No.99-18800-04801-00201-00801-01102-00202-00302-00402-00502-00602-00702-06902-07002-07102-07202-07302-07402-07603-00403-00503-00603-00703-00803-00903-01003-01603-01703-01803-01903-06003-06103-062Mercury ControlMercury ControlConfigurationPaired MercuryControl SampleLow NOxBurner (LNB)SO2ControlSO2ControlDescriptionAmmonia-BasedSystemNo No FGD-dry calcium Lime spray dryerNoNo No FGD-drySpray dryerUnknownNo LNB No UnknownNo LNB No UnknownNo No FGD-drySpray dryerUnknownActivated Carbon Injection Post-Primary PCD LNB No NoActivated Carbon Injection Post-Primary PCD LNB No NoActivated Carbon Injection Pre-Primary PCD No No NoActivated Carbon Injection Pre-Primary PCD No No NoActivated Carbon Injection Pre-Primary PCD No No NoActivated Carbon Injection Post-Primary PCD LNB No NoActivated Carbon Injection Post-Primary PCDHg control testsample of 02-070LNB w/overfire air No NoNo Baseline of 02-069LNB w/overfire air No NoActivated Carbon Injection Post-Primary PCDHg control testsample of 02-072LNB w/overfire air No NoNo Baseline of 02-071LNB w/overfire air No NoNoLNB w/overfire air No NoNoLNB w/overfire air No NoNoBaseline of 03-009,03-010 LNB No SNCRNo LNB No SCRNo LNB No SCRNo LNB No SCRNo LNB No SCRNo LNB NoSNCR: UreabasedActivated Carbon Injection Pre-Primary PCDHg control testsample of 02-076 LNB NoSNCR: UreabasedActivated Carbon Injection Pre-Primary PCDHg control testsample of 02-076 LNB NoSNCR: UreabasedNo No No NoActivated Carbon Injection No No NoActivated Carbon Injection No No NoActivated Carbon Injection No No NoFine Particulate Control +Activated Carbon InjectionHg control testsample of 03-061 No No NoFine Particulate Control Baseline of 03-060 No No NoActivated Carbon Injection No No NoPage 2 of 8ID No.CollectionDate Sample Type Sample Type Notes Sample Treatment Coal Type Coal NotesBurnerTypeParticulateCollectionParticulate CollectionDescription Collection Point03-063 10/2/2003 Fly Ash Eastern Bituminous High S OH pc-fired ESP Cold-side Silo03-065 10/2/2003 FGD Gypsum Eastern Bituminous High S OH pc-fired ESP Cold-side Stacker pad03-067 10/2/2003 FGD Slurrydewatered with Büchnerfunnel 05/03/05 – resultingliquid saved as 03-103 Eastern Bituminous High S OH pc-fired ESP Cold-side Before oxidizer03-078 10/30/2002 Fly Ash Fort Union Lignite Cyclone ESP Cold-side ESP Field03-079 10/30/2002 Fly Ash Fort Union Lignite Cyclone ESP Cold-side ESP Field03-080 10/30/2002 Fly Ash Fort Union Lignite Cyclone ESP Cold-side ESP Field03-081 10/30/2002 Fly Ash Fort Union Lignite Cyclone ESP Cold-side ESP Field03-082 11/18/2003 FGD Filtercakedewatered – resulting liquidsaved as 03-104 Eastern Bituminous pc-fired ESP Cold-side03-083 11/18/2003 Fly Ash Eastern Bituminous pc-fired ESP Cold-side03-084 11/18/2003 Fixated FGDportion ground & dried at<40°C for microbiologicalexperiment Eastern Bituminous pc-fired ESP Cold-side03-085 11/18/2003 Fly Ash Eastern Bituminous pc-fired ESP Cold-side Silo03-086 11/18/2003 FGD Filtercakewater poured off 1/18/06 –resulting liquid saved as 03-114 Eastern Bituminous pc-fired ESP Cold-sideVacuum filterdischarge03-087 11/18/2003 Fixated FGD Eastern Bituminous pc-fired ESP Cold-side Stockpile03-088 Fly Ash Eastern Bituminous pc-fired ESP Cold-side Silo03-089 FGD Gypsum Eastern Bituminous pc-fired ESP Cold-sideSolids from FGDgypsum filter plant03-103 10/2/2003 Lab dewatered FGD liquorlab dewatered 03-067:FGD slurry Eastern Bituminous High S OH pc-fired ESP Cold-side Lab generated03-104 11/18/2003 Lab dewatered FGD liquorlab dewatered 03-082:FGD filtercake Eastern Bituminous pc-fired ESP Cold-side Lab generated03-114 Lab dewatered FGD liquorlab dewatered 03-086:FGD filtercake Eastern Bituminous pc-fired ESP Cold-side Lab generated04-003 6/28/2002 Fly Ash Eastern Bituminous WV, KY, & PA; Low S pc-fired FF FF04-004 6/28/2002 Fly Ash Eastern Bituminous WV, KY, & PA; Low S pc-fired ESP Cold-side ESP Field04-006 11/1/1999 Fly Ash Western Bituminous CO pc-fired FF FF04-007 5/22/2003 Fly Ash Western Bituminous UT pc-fired FF FF04-029 Fly Ash PRB Subbituminous pc-fired COHPACESP-CS & COHPACFF/Mechanical ESP Field04-030 11/17/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fired ESP Cold-side ESP Hopper04-031 11/18/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fired ESP Cold-side ESP Hopper04-032 11/20/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fired ESP Cold-side ESP HopperPage 3 of 8ID No.03-06303-06503-06703-07803-07903-08003-08103-08203-08303-08403-08503-08603-08703-08803-08903-10303-10403-11404-00304-00404-00604-00704-02904-03004-03104-032Mercury ControlMercury ControlConfigurationPaired MercuryControl SampleLow NOxBurner (LNB)SO2ControlSO2ControlDescriptionAmmonia-BasedSystemNo No FGD-wet calcium Mg-enhanced lime NoNo No FGD-wet calcium Mg-enhanced lime NoNo No FGD-wet calcium Mg-enhanced lime NoNo No FGD-wet calciumLime with fly ashrecycle NoNo No FGD-wet calciumLime with fly ashrecycle NoNo No FGD-wet calciumLime with fly ashrecycle NoNo No FGD-wet calciumLime with fly ashrecycle NoNo No FGD-wet calcium Limestone sorbents SCRNo No FGD-wet calcium Limestone sorbents SCRNo No FGD-wet calcium Limestone sorbents SCRNo LNB FGD-wet calcium Limestone sorbentsSCR & AmmoniaInjectionNo LNB FGD-wet calcium Limestone sorbentsSCR & AmmoniaInjectionNo LNB FGD-wet calcium Limestone sorbentsSCR & AmmoniaInjectionNo LNB FGD-wet calciumLimestone-forcedoxidationSCR & AmmoniaInjectionNo LNB FGD-wet calciumLimestone-forcedoxidationSCR & AmmoniaInjectionNo No FGD-wet calcium Mg-enhanced lime NoNo No FGD-wet calcium Limestone sorbents SCRNo LNB FGD-wet calcium Limestone sorbentsSCR & AmmoniaInjectionNo No No NoNo No No NoNo No No NoNoLNB w/overfire air FGD-wet calcium Limestone sorbents NoNo LNB NoAmmoniaInjectionActivated Carbon Injection Post-Primary PCD LNB FGD-wet calciumLime-natural or in situoxidation NoActivated Carbon Injection Post-Primary PCD LNB FGD-wet calciumLime-natural or in situoxidation NoActivated Carbon Injection Post-Primary PCD LNB FGD-wet calciumLime-natural or in situoxidation NoPage 4 of 8ID No.CollectionDate Sample Type Sample Type Notes Sample Treatment Coal Type Coal NotesBurnerTypeParticulateCollectionParticulate CollectionDescription Collection Point04-033 11/20/2003 Fly Ash + Activated Carbon Fort Union Lignite pc-fired ESP Cold-side ESP Hopper04-035 3/24/2004 Fly Ash Fort Union Lignite pc-fired ESP Cold-side ESP Hopper04-036 4/27/2004Fly Ash + Enhancing Agent +Activated Carbon Fort Union Lignite pc-fired ESP Cold-side ESP Hopper04-042 5/11/2004 Fly Ash Gulf Coast Lignite Unknown ESP Cold-side ESP Field04-043 5/11/2004 Fly Ash Gulf Coast Lignite Unknown ESP Cold-side ESP Field04-044 5/11/2004 Fly Ash Gulf Coast Lignite Unknown ESP Cold-side ESP Field04-045 5/11/2004 Fly Ash Gulf Coast Lignite Unknown ESP Cold-side ESP Field04-054 11/18/2003 Fly Ash + Activated Carbon Eastern Bituminous Low S washed pc-fired COHPACESP-HS & COHPACFF FF04-067 5/21/2004Fly Ash + Enhancing Agent +Activated Carbon Fort Union Lignite pc-fired ESP Cold-side ESP Field04-082 8/19/2004 FGD Gypsum Eastern Bituminous pc-fired ESP Cold-sideVacuum drying beltat gypsumprocessing facilityafter drying04-083 11/8/2004 FGD Gypsum Eastern Bituminous pc-fired ESP Cold-sideVacuum drying beltat gypsumprocessing facilityafter drying05-001 2/2/2005 Fly Ash Fort Union Lignite pc-fired FF FF05-002 2/2/2005 FGD-SDA Fort Union Lignite pc-fired FF SDA Hopper05-003 2/24/2005Fly Ash + Enhancing Agent +Activated Carbon Fort Union Lignite pc-fired FF FF05-004 2/24/2005FGD-SDA + EnhancingAgent + Activated Carbon Fort Union Lignite pc-fired FF SDA Hopper05-005 3/17/2005 Fly Ash Fort Union Lignite Cyclone ESP Cold-side ESP Hopper05-009 7/19/2005 FGD Gypsum Eastern Bituminous High S Ohio pc-fired ESP Cold-side Stockpile05-010 7/19/2005 Fly Ash Eastern Bituminous High S Ohio pc-fired ESP Cold-side ESP Hopper05-011 7/19/2005 FGD Gypsum Filtrate Eastern Bituminous High S Ohio pc-fired ESP Cold-side Filtrate pumps05-013 4/16/2005 Fly Ash + Activated Carbon Fort Union Lignite pc-fired FF FF05-017 4/13/2005 Fly Ash + Enhancing Agent Fort Union Lignite Cyclone ESP Cold-side ESP Hopper05-018 8/17/2005 Fly Ash Eastern Bituminous pc-fired ESP Cold-side Silo05-019 8/17/2005 FGD Filtercakewater poured off 9/21/05 &solid pressed – resultingliquid saved as 05-032 Eastern Bituminous pc-fired ESP Cold-sideVacuum filterdischarge05-020 8/17/2005 Fixated FGD Eastern Bituminous pc-fired ESP Cold-side Stockpile05-022 8/17/2005 FGD Filtrate Eastern Bituminous pc-fired ESP Cold-side Filtrate pumps05-023 5/14/2005 Fly Ash + Activated Carbon Fort Union Lignite pc-fired FF FFPage 5 of 8ID No.04-03304-03504-03604-04204-04304-04404-04504-05404-06704-08204-08305-00105-00205-00305-00405-00505-00905-01005-01105-01305-01705-01805-01905-02005-02205-023Mercury ControlMercury ControlConfigurationPaired MercuryControl SampleLow NOxBurner (LNB)SO2ControlSO2ControlDescriptionAmmonia-BasedSystemActivated Carbon Injection Post-Primary PCD LNB FGD-wet calciumLime-natural or in situoxidation NoNo Baseline of 04-036LNB w/overfire air No NoActivated Carbon Injection +Enhancing Agent Injection Pre-Primary PCDHg control testsample of 04-035LNB w/overfire air No NoNo LNB FGD-wet calcium Limestone sorbents NoNo LNB FGD-wet calcium Limestone sorbents NoNo LNB FGD-wet calcium Limestone sorbents NoNo LNB FGD-wet calcium Limestone sorbents NoActivated Carbon Injection Post-Primary PCD LNB No NoActivated Carbon Injection +Enhancing Agent InjectionEnhancing Agent onCoal, ACI Pre-PrimaryPCDLNB w/overfire air No NoNo No FGD-wet calciumLimestone-forcedoxidation SCRNo No FGD-wet calciumLimestone-forcedoxidation NoNo Baseline of 05-003 No FGD-drySpray dryerNoNo Baseline of 05-004 No FGD-drySpray dryerNoActivated Carbon Injection +Enhancing Agent InjectionEnhancing Agent onCoal, ACI before SDAHg control testsample of 05-001 No FGD-dry Spray dryer NoActivated Carbon Injection +Enhancing Agent InjectionEnhancing Agent onCoal, ACI before SDAHg control testsample of 05-002 No FGD-dry Spray dryer NoNo Baseline of 05-017 No FGD-wet calciumLime with fly ashrecycle NoNo No FGD-wet calcium Mg-enhanced lime NoNo No FGD-wet calcium Mg-enhanced lime NoNo No FGD-wet calcium Mg-enhanced lime NoActivated Carbon Injection Post-Primary PCDHg control testsample of 05-038 No No NoEnhancing Agent InjectionEnhancing Agent onCoalHg control testsample of 05-005 No FGD-wet calciumLime with fly ashrecycle NoNo LNB FGD-wet calcium Limestone sorbentsSCR & AmmoniaInjectionNo LNB FGD-wet calcium Limestone sorbentsSCR & AmmoniaInjectionNo LNB FGD-wet calcium Limestone sorbentsSCR & AmmoniaInjectionNo LNB FGD-wet calcium Limestone sorbentsSCR & AmmoniaInjectionActivated Carbon InjectionPost-Primary PCD:High fly ash contentHg control testsample of 05-038 No No NoPage 6 of 8ID No.CollectionDate Sample Type Sample Type Notes Sample Treatment Coal Type Coal NotesBurnerTypeParticulateCollectionParticulate CollectionDescription Collection Point05-024 5/29/2005 Fly Ash + Activated Carbon Fort Union Lignite pc-fired FF FF05-025 8/23/2005 Fly Ash + Activated Carbon Fort Union Lignite pc-fired FF FF05-032 Lab dewatered FGD liquorlab filtered 05-019:FGD filtercake Eastern Bituminous pc-fired ESP Cold-side Lab generated05-038 10/18/2005 Fly Ash Fort Union Lignite pc-fired FF FF05-040 11/1/2005 Fly Ash + Activated Carbon Fort Union Lignite pc-fired FF FF06-001 11/17/2005 Fly Ash + Activated Carbon Fort Union Lignite pc-fired FF FFPage 7 of 8ID No.05-02405-02505-03205-03805-04006-001Mercury ControlMercury ControlConfigurationPaired MercuryControl SampleLow NOxBurner (LNB)SO2ControlSO2ControlDescriptionAmmonia-BasedSystemActivated Carbon Injection Post-Primary PCDHg control testsample of 05-038 No No NoActivated Carbon InjectionPost-Primary PCD:High fly ash contentHg control testsample of 05-038 No No NoNo LNB FGD-wet calcium Limestone sorbentsSCR & AmmoniaInjectionNoBaseline of 05-013,05-023, 05-024, 05-025, 05-040, 06-001 No No NoActivated Carbon Injection Post-Primary PCDHg control testsample of 05-038 No No NoActivated Carbon Injection Post-Primary PCDHg control testsample of 05-038 No No NoPage 8 of 8

# APPENDIX G

TOTAL TRACE ELEMENTAL DATAID No. Sample Type Mercury Control Configuration Coal Type As (μg/g) Cd (μg/g) Cr (μg/g) Pb (μg/g) Hg (μg/g) Ni (μg/g) Se (μg/g) Total Trace Elemental Comments99-188 FGD-SDA PRB Subbituminous 14.7 <1 26.3 37 0.112 12.9 9.9202-002 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 55.602-003 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 32.002-004 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 1.0902-005 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 5.0002-006 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 37.4 1.97 111 60.2 5.81 50.6 69.402-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 60.502-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 12002-069 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 0.74202-070 Fly Ash Eastern Bituminous 0.19002-070 Fly Ash Eastern Bituminous 0.19702-071 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 0.97502-072 Fly Ash Eastern Bituminous 0.16302-073 Fly Ash Eastern Bituminous 0.23402-074 Fly Ash Eastern Bituminous 0.61302-076 Fly AshSouth AmericanBituminous 0.60703-004 Fly Ash Eastern Bituminous 72.2 <1 142 65.4 0.097 68.3 7.9303-005 Fly Ash Eastern Bituminous 71.4 <1 148 72.6 0.084 85.7 8.5403-006 Fly Ash Eastern Bituminous 78.0 1.36 135 94.3 0.194 60.4 13.603-007 Fly Ash Eastern Bituminous 68.6 1.13 138 89.0 0.141 55.2 11.403-007 Fly Ash Eastern Bituminous 72.1 <1 135 72.4 87.4 12.203-008 Fly AshSouth AmericanBituminous 0.15103-016 Fly Ash Fort Union Lignite 33.7 <1 59.6 25.6 0.016 59.5 13.003-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 40.1 <1 57.7 30.4 0.225 56.5 13.503-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 54.7 <1 61.5 40.4 0.289 54.0 14.803-019 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 73.9 <1 64.8 47.4 2.22 51.4 21.703-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 19.4 1.87 76.7 82.2 1.86 67.6 34.203-061 Fly Ash PRB Subbituminous 37.8 1.78 44.2 58.1 0.578 79.0 44.303-061 Fly Ash PRB Subbituminous 49.2 1.52 76.1 62.1 10703-061 Fly Ash PRB Subbituminous 43.4 1.86 82.4 58.4 95.8 44.703-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 43.3 <1 54.4 30.3 0.490 57.6 13.403-063 Fly Ash Eastern Bituminous 45.5 <1 128 37.1 <0.1 23.3 4.9403-065 FGD Gypsum Eastern Bituminous <1 <1 2.90 <3 <0.1 <1 <203-067 FGD SlurryEastern Bituminous 0.12003-067 FGD SlurryEastern Bituminous 0.196 3.01 Dewatered sample03-067 FGD SlurryEastern Bituminous <1 <1 6.61 <3 <0.1 2.8703-078 Fly Ash Fort Union Lignite 0.66203-079 Fly Ash Fort Union Lignite 351 2.1 83.2 68.3 0.785 40.9 14.703-080 Fly Ash Fort Union Lignite 157 1.06 66.1 39.9 0.440 63.5 11.903-081 Fly Ash Fort Union Lignite 492 3.60 85.2 124 0.459 68.4 18.103-082 FGD Filtercake Eastern Bituminous <1 <1 10.4 <3 0.218 3.50 <203-082 FGD Filtercake Eastern Bituminous 0.248 <2 Dewatered sample03-083 Fly Ash Eastern Bituminous 163 3.48 134 258 252 4.7803-083 Fly Ash Eastern Bituminous 169 3.66 139 272 0.017 266 3.9703-084 Fixated FGD Eastern Bituminous 53.4 1.24 53.6 80.3 0.180 87.2 4.4603-085 Fly Ash Eastern Bituminous 145 2.55 124 247 0.034 277 4.0403-086 FGD Filtercake Eastern Bituminous <1 <1 10.2 4.40 0.162 3.98 2.6403-087 Fixated FGD Eastern Bituminous 53.8 1.08 51.6 86.7 0.136 98.7 3.7103-088 Fly Ash Eastern Bituminous 44 8.59 160 249 0.010 74.5 7.42Page 1 of 2ID No. Sample Type Mercury Control Configuration Coal Type As (μg/g) Cd (μg/g) Cr (μg/g) Pb (μg/g) Hg (μg/g) Ni (μg/g) Se (μg/g) Total Trace Elemental Comments03-089 FGD Gypsum Eastern Bituminous <1 1.89 4.13 <3 <0.1 <1 <203-089 FGD Gypsum Eastern Bituminous 0.09604-003 Fly Ash Eastern Bituminous 49.8 <1 138 60.4 77.2 19.304-003 Fly Ash Eastern Bituminous 42.2 <1 132 60.5 0.685 75.9 19.104-004 Fly Ash Eastern Bituminous 31.5 <1 144 55.7 0.041 81.6 5.7704-006 Fly Ash Western Bituminous 5.90 <1 43.8 38.8 0.144 26.1 10.204-007 Fly Ash Western Bituminous 7.09 <1 64.9 29.1 0.521 22.0 13.504-029 Fly Ash PRB Subbituminous 31.1 1.07 63.7 38.6 0.261 39.9 15.704-030 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 136 3.34 92.8 85.3 0.147 24.2 28.104-031 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 134 3.24 91.8 83.4 0.174 28.2 31.204-032 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 161 3.38 94.8 74.9 0.470 40.0 19.604-033 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 148 2.91 86.5 74.9 1.43 29.1 23.204-035 Fly Ash Fort Union Lignite 36.0 <1 55.4 21.9 0.159 17.2 9.7804-036Fly Ash + Activated Carbon +Enhancing AgentEnhancing Agent on Coal, ACIPre-Primary PCD Fort Union Lignite 43.4 <1 48.4 18.3 0.287 23.1 11.004-036Fly Ash + Activated Carbon +Enhancing AgentEnhancing Agent on Coal, ACIPre-Primary PCD Fort Union Lignite 46.3 <1 49.1 19.1 23.8 9.8604-042 Fly Ash Gulf Coast Lignite 0.37104-043 Fly Ash Gulf Coast Lignite 0.68904-044 Fly Ash Gulf Coast Lignite 0.87804-045 Fly Ash Gulf Coast Lignite 0.84904-054 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 444 1.16 115 49.0 17.7 94.5 45704-067Fly Ash + Activated Carbon +Enhancing AgentEnhancing Agent on Coal, ACIPre-Primary PCD Fort Union Lignite 26.8 <1 44.8 25.9 0.640 41.5 18.304-082 FGD Gypsum Eastern Bituminous 1.65 <1 3.39 <3 0.043 6.83 2.5604-083 FGD Gypsum Eastern Bituminous <2 <1 3.95 <3 0.103 6.81 2.6805-001 Fly Ash Fort Union Lignite 24.4 <1 45.1 17.4 <0.01 30.3 8.8405-002 FGD-SDA Fort Union Lignite 22.6 <1 42.8 18.6 <0.01 29.7 9.1505-003Fly Ash + Activated Carbon +Enhancing AgentEnhancing Agent on Coal, ACIbefore SDA Fort Union Lignite 28.6 <1 45.5 21.2 0.565 25.7 11.505-004FGD-SDA + ActivatedCarbon + Enhancing AgentEnhancing Agent on Coal, ACIbefore SDA Fort Union Lignite 21.8 <1 37.3 20.9 0.332 25.3 9.7905-005 Fly Ash Fort Union Lignite 0.43105-009 FGD Gypsum Eastern Bituminous 0.03205-010 Fly Ash Eastern Bituminous 0.08005-013 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 38.6 <1 36.5 73.2 39.0 15.4 60.305-017 Fly Ash + Enhancing AgentEnhancing Agent on Coal Fort Union Lignite 0.71705-018 Fly Ash Eastern Bituminous 0.12305-019 FGD Filtercake Eastern Bituminous 0.30505-020 Fixated FGD Eastern Bituminous 0.24905-023 Fly Ash + Activated CarbonPost-Primary PCD: High fly ashcontent Fort Union Lignite 48.3 <1 42.6 87.1 12.7 18.6 22.505-024 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 42.5 <1 35.5 82.2 35.9 17.6 87.305-025 Fly Ash + Activated CarbonPost-Primary PCD: High fly ashcontent Fort Union Lignite 46.8 <1 39.1 84.7 12.6 20.4 30.105-038 Fly Ash Fort Union Lignite 43.4 <1 43.4 90.1 0.104 21.1 23.405-040 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 38.4 <1 42.2 74.5 44.5 22.0 42.206-001 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 35.3 <1 40.5 71.2 64.5 20.6 38.906-001 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 35.6 <1 39.0 72.7 20.5 38.8Page 2 of 2

# APPENDIX H

FGD LIQUOR TOTAL TRACE ELEMENTAL CONCENTRATION AND pH DATAID No. Sample Type Sample Type Notes Coal TypeAs (μg/L) Cd (μg/L) Cr (μg/L) Pb (μg/L) Hg (μg/L) Ni (μg/L) Se (μg/L) pH03-103Lab dewateredFGD liquorlab dewatered 03-067:FGD slurryEasternBituminous 114 0.79 10.1 <2 <0.15 258 1140 6.7503-104Lab dewateredFGD liquorlab dewatered 03-082:FGD filtercakeEasternBituminous 54.4 2.89 2.9 <2 <0.15 333 154 6.7303-114Lab dewateredFGD liquorlab dewatered 03-086:FGD filtercakeEasternBituminous 121 4.34 4.3 <2 NT 123 759 7.5605-011FGD GypsumFiltrateEasternBituminous 82.8 4.79 9.9 <2 <0.01 338 684 5.2005-032Lab dewateredFGD liquorlab filtered 05-019:FGD filtercakeEasternBituminous 33.1 2.09 5.7 <2 NT 88.8 305 5.92Page 1 of 2ID No. Sample Type Sample Type Notes Coal TypeSamplePrep10–15-MinpH10–15-MinpH Date 24-Hr pH24-Hr pHDate03-103 Lab dewatered FGD liquorlab dewatered 03-067:FGD slurry Eastern Bituminous 6.73 5/3/200503-103 Lab dewatered FGD liquorlab dewatered 03-067:FGD slurry Eastern Bituminous filtered 6.75 5/3/200503-103 Lab dewatered FGD liquorlab dewatered 03-067:FGD slurry Eastern Bituminous 6.78 6/21/2006 7.38 6/22/200603-104 Lab dewatered FGD liquorlab dewatered 03-082:FGD filtercake Eastern Bituminous 6.53 5/3/200503-104 Lab dewatered FGD liquorlab dewatered 03-082:FGD filtercake Eastern Bituminous filtered 6.73 5/3/200503-114 Lab dewatered FGD liquorlab dewatered 03-086:FGD filtercake Eastern Bituminous 6.99 6/15/2006 7.51 6/16/200603-114 Lab dewatered FGD liquorlab dewatered 03-086:FGD filtercake Eastern Bituminous 7.36 8/1/2006 7.56 8/2/200605-011 FGD Gypsum Filtrate Eastern Bituminous 5.44 5/8/2006 5.25 5/9/200605-011 FGD Gypsum Filtrate Eastern Bituminous 5.40 8/1/2006 5.20 8/2/200605-022 FGD Filtrate Eastern Bituminous 7.26 5/8/2006 8.13 5/9/200605-022 FGD Filtrate Eastern Bituminous 7.20 8/1/2006 8.17 8/2/200605-032 Lab dewatered FGD liquorlab filtered 05-019: FGDfiltercake Eastern Bituminous 6.75 6/13/2006 7.47 6/14/200605-032 Lab dewatered FGD liquorlab filtered 05-019: FGDfiltercake Eastern Bituminous 6.63 8/1/2006 5.92 8/2/2006Page 2 of 2

# APPENDIX I

TOTAL BULK CHEMICAL COMPOSITION DATA,

REPORTED AS OXIDESID No. Sample TypeMercuryControlConfiguration Coal TypeSiO2(%) Al2O3(%) Fe2O3(%)CaO (%) MgO (%)Na2O (%) K2O (%) TiO2(%) MnO2(%) P2O5(%)SrO (%) BaO (%)SO3(%)LOI (%)Moisture, asReceived (%)99-188 FGD-SDAPRBSubbituminous 30.79 17.69 3.54 25.68 2.93 1.65 0.48 0.59 0.09 0.63 0.45 0.37 13.60 1.49 1.0103-004 Fly AshEasternBituminous 55.23 27.48 6.37 1.44 0.78 0.37 2.47 1.62 0.02 0.40 0.11 0.14 0.12 3.46 0.1203-005 Fly AshEasternBituminous 55.29 27.51 5.84 1.54 0.91 0.41 2.59 1.64 0.04 0.36 0.11 0.14 0.06 3.56 0.1203-006 Fly AshEasternBituminous 55.83 27.51 6.65 1.34 0.96 0.41 2.57 1.66 0.03 0.35 0.11 0.13 0.07 2.40 0.1403-007 Fly AshEasternBituminous 54.88 27.62 5.77 1.32 0.90 0.33 2.60 1.64 0.02 0.35 0.10 0.13 0.08 4.25 0.1203-016 Fly Ash Fort Union Lignite 44.19 15.87 7.34 17.67 5.56 4.39 1.61 0.60 0.05 0.13 0.42 0.73 1.13 0.32 0.0103-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 40.46 15.24 7.59 19.38 6.62 4.79 1.33 0.58 0.08 0.20 0.45 0.81 1.43 1.04 0.0903-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 38.71 15.64 6.54 19.95 6.80 5.02 1.37 0.60 0.07 0.19 0.48 0.98 2.74 0.91 0.0503-019 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 35.23 14.87 5.63 18.86 6.38 5.12 1.31 0.57 0.07 0.20 0.49 1.16 5.89 4.22 0.2303-060 Fly Ash + Activated Carbon Pre-Primary PCDPRBSubbituminous 30.07 17.63 5.87 27.50 6.11 2.42 0.68 1.35 0.02 2.32 0.44 0.84 2.54 2.22 0.0903-061 Fly AshPRBSubbituminous 22.64 17.25 6.87 31.56 8.48 2.99 0.49 1.21 0.03 1.24 0.49 0.87 4.73 1.15 0.1103-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 40.30 15.61 7.31 19.37 5.95 4.91 1.32 0.58 0.08 0.20 0.46 0.87 1.86 1.17 0.0503-063 Fly AshEasternBituminous 41.01 18.78 32.46 2.88 0.72 0.41 1.58 0.96 0.05 0.20 0.04 0.06 0.34 0.52 0.0203-065 FGD GypsumEasternBituminous 0.39 0.05 0.03 34.69 0.91 0.00 0.01 0.02 0.01 0.03 0.01 0.03 51.14 12.68 17.37Page 1 of 1

# APPENDIX J

MOISTURE CONTENT AND LOI DATAID No. Sample Type Hg Control Configuration Coal Type Moisture Content, % LOI, %

99-188 FGD-SDA PRB Subbituminous 1.18% 2.07% 02-002 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 5.56% 22.2% 02-002 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 4.07% 24.2% 02-003 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 2.92% 19.4% 02-003 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 2.59% 19.3% 02-004 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 0.53% 2.84% 02-005 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 0.72% 4.14% 02-006 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 1.07% 3.88% 02-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 4.63% 23.9% 02-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 3.99% 24.3% 02-069 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 0.86% 12.6% 02-069 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 0.69% 12.6% 02-070 Fly Ash Eastern Bituminous 0.24% 5.88% 02-070 Fly Ash Eastern Bituminous 0.15% 5.85% 02-071 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 1.18% 17.2% 02-072 Fly Ash Eastern Bituminous 0.13% 5.18% 02-072 Fly Ash Eastern Bituminous 0.21% 5.39% 02-073 Fly Ash Eastern Bituminous 0.14% 5.00% 02-074 Fly Ash Eastern Bituminous 0.36% 6.27% 02-074 Fly Ash Eastern Bituminous 0.22% 6.09%

02-076 Fly Ash South American

Bituminous 0.60% 21.1%

02-076 Fly Ash South American

Bituminous 0.44% 21.0% 03-004 Fly Ash Eastern Bituminous 0.12% 3.48% 03-004 Fly Ash Eastern Bituminous 0.15% 3.20% 03-005 Fly Ash Eastern Bituminous 0.17% 3.59% 03-005 Fly Ash Eastern Bituminous 0.18% 3.60% 03-006 Fly Ash Eastern Bituminous 0.18% 5.28% 03-006 Fly Ash Eastern Bituminous 0.21% 5.19% 03-006 Fly Ash Eastern Bituminous 0.12% 5.24% 03-007 Fly Ash Eastern Bituminous 0.15% 4.54% 03-007 Fly Ash Eastern Bituminous 0.19% 4.41%

03-008 Fly Ash South American

Bituminous 0.15% 12.7%

03-009 Fly Ash + Activated Carbon Pre-Primary PCD South American

Bituminous NT NT

03-010 Fly Ash + Activated Carbon Pre-Primary PCD South American

Bituminous NT NT 03-016 Fly Ash Fort Union Lignite 0.05% 0.34% 03-016 Fly Ash Fort Union Lignite 0.04% 0.24% 03-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.06% 0.96% 03-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.10% 1.23% 03-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.12% 1.17% 03-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.09% 0.97% 03-019 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.61% 4.21% 03-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 0.18% 2.47% 03-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 0.15% 2.28% 03-061 Fly Ash PRB Subbituminous 0.19% 1.00% 03-061 Fly Ash PRB Subbituminous 0.14% 1.08%

Page 1 of 3ID No. Sample Type Hg Control Configuration Coal Type Moisture Content, % LOI, % 03-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.10% 1.29% 03-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 0.02% 1.26% 03-063 Fly Ash Eastern Bituminous 0.06% 0.47% 03-065 FGD Gypsum Eastern Bituminous 25.7% 1.22%

03-067 FGD Slurr y Eastern Bituminous 56.8% 4.37%

03-067 FGD Slurr y Eastern Bituminous 65.7% 6.38% 03-078 Fly Ash Fort Union Lignite 0.48% 1.47% 03-079 Fly Ash Fort Union Lignite 0.28% 2.54% 03-080 Fly Ash Fort Union Lignite 0.45% 7.48% 03-081 Fly Ash Fort Union Lignite 0.68% 1.15%

03-082 FGD Filtercake Eastern Bituminous 28.9% 5.04%

03-082 FGD Filtercake Eastern Bituminous 40.0% 4.20%

03-082 FGD Filtercake Eastern Bituminous 28.6% 4.86% 03-083 Fly Ash Eastern Bituminous 0.15% 1.20%

03-084 Fixated FGD Eastern Bituminous 26.6% 3.17%

03-084 Fixated FGD Eastern Bituminous 27.1% 3.11% 03-085 Fly Ash Eastern Bituminous 0.16% 2.10%

03-086 FGD Filtercake Eastern Bituminous 43.3% 5.87%

03-087 Fixated FGD Eastern Bituminous 31.3% 3.80%

03-087 Fixated FGD Eastern Bituminous 31.9% 4.17% 03-088 Fly Ash Eastern Bituminous 0.17% 1.07% 03-089 FGD Gypsum Eastern Bituminous 21.6% 1.94% 04-003 Fly Ash Eastern Bituminous 0.16% 8.46% 04-003 Fly Ash Eastern Bituminous 0.24% 8.44% 04-004 Fly Ash Eastern Bituminous 0.13% 1.38% 04-004 Fly Ash Eastern Bituminous 0.11% 1.38% 04-006 Fly Ash Western Bituminous 0.17% 1.42% 04-007 Fly Ash Western Bituminous 0.08% 2.56% 04-007 Fly Ash Western Bituminous 0.05% 2.46% 04-029 Fly Ash PRB Subbituminous 0.14% 0.48% 04-030 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.14% 0.76% 04-030 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.13% 0.62% 04-031 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.11% 0.67% 04-031 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.18% 0.59% 04-032 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.11% 1.09% 04-032 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.40% 0.93% 04-033 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.43% 1.39% 04-033 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.22% 1.27% 04-035 Fly Ash Fort Union Lignite 0.19% 2.45% 04-035 Fly Ash Fort Union Lignite 0.16% 2.68% 04-035 Fly Ash Fort Union Lignite 0.06% 2.24%

04-036 Fly Ash + Enhancing Agent +

Activated Carbon Enhancing Agent onCoal, ACI PrePrimary PCD Fort Union Lignite 0.05% 2.49%

04-036 Fly Ash + Enhancing Agent +

Activated Carbon Enhancing Agent onCoal, ACI PrePrimary PCD Fort Union Lignite 0.07% 2.16% 04-054 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 0.60% 18.6%

Page 2 of 3ID No. Sample Type Hg Control Configuration Coal Type Moisture Content, % LOI, %

04-067 Fly Ash + Enhancing Agent +

Activated Carbon Enhancing Agent onCoal, ACI PrePrimary PCD Fort Union Lignite 0.06% 2.11% 04-082 FGD Gypsum Eastern Bituminous 26.5% 1.60% 04-083 FGD Gypsum Eastern Bituminous 26.6% 2.26% 05-001 Fly Ash Fort Union Lignite 1.00% 0.90% 05-002 FGD-SDA Fort Union Lignite 1.08% 0.95%

05-003 Fly Ash + Enhancing Agent +

Activated Carbon Enhancing Agent on Coal, ACI before SDA Fort Union Lignite 0.85% 1.04%

05-004 FGD-SDA + Enhancing Agent + Activated Carbon Enhancing Agent on Coal, ACI before SDA Fort Union Lignite 0.75% 1.12% 05-005 Fly Ash Fort Union Lignite 0.02% 1.29% 05-009 FGD Gypsum Eastern Bituminous 26.1% 1.92% 05-010 Fly Ash Eastern Bituminous 0.33% 2.05% 05-013 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.29% 13.2%

05-017 Fly Ash + Enhancing Agent Enhancing Agent on Coal Fort Union Lignite 0.05% 1.70% 05-018 Fly Ash Eastern Bituminous 0.04% 3.01%

05-019 FGD Filtercake Eastern Bituminous 33.3% 6.19%

05-020 Fixated FGD Eastern Bituminous 31.1% 3.65%

05-023 Fly Ash + Activated Carbon Post-Primary PCD: High Ash Fort Union Lignite 0.13% 3.84% 05-024 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.23% 9.45%

05-025 Fly Ash + Activated Carbon Post-Primary PCD: High Ash Fort Union Lignite 0.13% 3.20%

05-025 Fly Ash + Activated Carbon Post-Primary PCD: High Ash Fort Union Lignite 0.00% 3.18% 05-038 Fly Ash Fort Union Lignite 0.04% 0.22% 05-040 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.10% 9.68% 06-001 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 0.39% 11.6%

Page 3 of 3

# APPENDIX K

pH DATAID No. Sample Type Mercury Control Configuration Coal TypeSamplePrep10–15-MinpH10–15-MinpH Date 24-Hr pH24-Hr pHDateOvernightpHOvernightpH Date1 M KClpH1 M KClpH Date99-188 FGD-SDA PRB Subbituminous 12.41 5/2/2006 12.22 5/3/2006 12.53 9/1/200499-188 FGD-SDA PRB Subbituminous 12.34 1/17/2002 12.53 9/10/200402-002 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 3.62 7/27/2004 3.51 9/15/200402-003 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 4.19 5/24/2006 4.76 5/25/2006 3.98 9/15/200402-003 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 3.91 7/27/200402-004 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 11.47 7/27/200402-005 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 10.65 7/27/200402-006 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 10.99 5/24/2006 10.95 5/25/2006 10.48 8/31/200402-006 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 10.86 4/8/200402-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 3.47 5/24/2006 3.99 5/25/2006 3.52 9/15/200402-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 3.54 7/27/200402-069 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 8.85 5/24/2006 8.43 5/25/200602-069 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 8.94 7/27/200402-069 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 9.00 9/26/200202-070 Fly Ash Eastern Bituminous 9.98 5/24/2006 8.50 5/25/2006 10.11 9/13/200402-070 Fly Ash Eastern Bituminous 10.25 9/26/200202-071 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 9.26 5/24/2006 8.63 5/25/2006 9.38 9/13/200402-071 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 9.59 9/26/200202-072 Fly Ash Eastern Bituminous 10.09 5/24/2006 8.83 5/25/200602-072 Fly Ash Eastern Bituminous 10.35 9/26/2002 10.16 9/1/200402-073 Fly Ash Eastern Bituminous 12.18 5/24/2006 12.44 5/25/2006 12.72 9/13/200402-073 Fly Ash Eastern Bituminous 12.56 9/26/200202-074 Fly Ash Eastern Bituminous 12.00 5/30/2006 11.80 5/31/2006 12.69 9/13/200402-074 Fly Ash Eastern Bituminous 12.18 9/26/200202-076 Fly AshSouth AmericanBituminous 10.38 5/30/2006 9.13 5/31/2006 10.66 9/10/200402-076 Fly AshSouth AmericanBituminous 9.93 10/19/200403-004 Fly Ash Eastern Bituminous 4.54 5/30/2006 7.08 5/31/2006 4.69 9/15/200403-004 Fly Ash Eastern Bituminous 4.26 9/29/200303-005 Fly Ash Eastern Bituminous 4.45 5/30/2006 5.88 5/31/2006 4.48 9/15/200403-005 Fly Ash Eastern Bituminous 4.26 9/29/200303-006 Fly Ash Eastern Bituminous 4.82 4/26/2006 6.78 4/27/2006 4.72 9/15/200403-006 Fly Ash Eastern Bituminous 4.60 9/29/200303-007 Fly Ash Eastern Bituminous 4.38 4/26/2006 5.52 4/27/2006 4.42 9/15/200403-007 Fly Ash Eastern Bituminous 4.15 9/29/200303-008 Fly AshSouth AmericanBituminous 11.72 3/14/200303-009 Fly Ash + Activated Carbon Pre-Primary PCDSouth AmericanBituminous 11.79 3/14/200303-010 Fly Ash + Activated Carbon Pre-Primary PCDSouth AmericanBituminous 10.34 3/14/200303-016 Fly Ash Fort Union Lignite 12.63 5/30/2006 12.54 5/31/2006 12.82 9/1/200403-016 Fly Ash Fort Union Lignite 12.60 9/29/2003 12.84 9/10/200403-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 12.69 6/1/2006 12.61 6/2/200603-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 12.57 9/29/2003 12.84 8/31/200403-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 12.58 6/1/2006 12.38 6/2/2006 12.76 8/31/200403-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 12.57 9/29/200303-019 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 11.92 6/1/2006 11.86 6/2/2006 12.38 9/1/200403-019 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 11.74 10/9/2003 12.46 9/10/2004Page 1 of 4ID No. Sample Type Mercury Control Configuration Coal TypeSamplePrep10–15-MinpH10–15-MinpH Date 24-Hr pH24-Hr pHDateOvernightpHOvernightpH Date1 M KClpH1 M KClpH Date03-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 11.31 6/1/2006 11.90 6/2/2006 10.95 9/1/200403-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 11.32 10/9/2003 11.16 9/10/200403-061 Fly Ash PRB Subbituminous 11.91 6/1/2006 12.56 6/2/2006 11.96 8/31/200403-061 Fly Ash PRB Subbituminous 12.02 10/10/200303-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 12.67 6/1/2006 12.60 6/2/2006 12.81 8/30/200403-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite 12.57 10/10/200303-063 Fly Ash Eastern Bituminous 10.98 6/1/2006 11.00 6/2/2006 11.62 9/10/200403-063 Fly Ash Eastern Bituminous 11.30 12/3/200303-065 FGD Gypsum Eastern Bituminous 8.07 5/2/2006 7.75 5/3/200603-065 FGD Gypsum Eastern Bituminous 8.59 12/3/200303-067 FGD SlurryEastern Bituminous dewatered 8.95 6/21/2006 8.75 6/22/200603-067 FGD SlurryEastern Bituminous dewatered 7.84 8/25/200503-067 FGD SlurryEastern Bituminous 8.05 6/9/200403-078 Fly Ash Fort Union Lignite 11.59 12/3/200303-079 Fly Ash Fort Union Lignite 11.81 6/1/2006 11.62 6/2/2006 11.63 9/13/200403-079 Fly Ash Fort Union Lignite 11.72 12/3/200303-080 Fly Ash Fort Union Lignite 11.72 6/13/2006 11.68 6/14/200603-080 Fly Ash Fort Union Lignite 11.64 12/3/2003 11.84 8/30/200403-081 Fly Ash Fort Union Lignite 11.20 6/13/2006 10.50 6/14/2006 11.05 8/30/200403-081 Fly Ash Fort Union Lignite 11.26 12/3/200303-082 FGD Filtercake Eastern Bituminous 8.18 5/8/2006 7.85 5/9/200603-082 FGD Filtercake Eastern Bituminous 7.47 6/9/200403-083 Fly Ash Eastern Bituminous 4.75 6/13/2006 9.00 6/14/2006 4.59 9/15/200403-083 Fly Ash Eastern Bituminous 4.28 12/3/200303-084 Fixated FGD Eastern Bituminous 11.57 6/13/2006 11.03 6/14/2006 12.30 9/13/200403-084 Fixated FGD Eastern Bituminous 12.52 12/3/200303-085 Fly Ash Eastern Bituminous 9.54 5/8/2006 8.79 5/9/200603-085 Fly Ash Eastern Bituminous 7.06 12/3/200303-086 FGD Filtercake Eastern Bituminous 7.81 6/13/2006 7.70 6/14/200603-086 FGD Filtercake Eastern Bituminous 7.70 6/9/200403-087 Fixated FGD Eastern Bituminous 10.87 6/13/2006 10.50 6/14/2006 11.75 9/13/200403-087 Fixated FGD Eastern Bituminous 12.51 12/3/200303-088 Fly Ash Eastern Bituminous 10.72 5/2/2006 11.15 5/3/200603-088 Fly Ash Eastern Bituminous 5.02 2/12/200403-088 Fly Ash Eastern Bituminous 7.50 4/8/200403-089 FGD Gypsum Eastern Bituminous 8.13 5/2/2006 7.95 5/3/200603-089 FGD Gypsum Eastern Bituminous 8.22 4/15/200404-003 Fly Ash Eastern Bituminous 9.36 4/26/2006 8.54 4/27/2006 9.42 9/1/200404-003 Fly Ash Eastern Bituminous 9.34 2/12/200404-004 Fly Ash Eastern Bituminous 9.89 4/26/2006 8.92 4/27/2006 10.10 9/1/200404-004 Fly Ash Eastern Bituminous 4.47 2/12/200404-004 Fly Ash Eastern Bituminous 10.29 4/8/200404-006 Fly Ash Western Bituminous 11.56 6/13/2006 10.38 6/14/2006 11.76 9/1/200404-006 Fly Ash Western Bituminous 11.52 3/4/2004 11.73 9/1/200404-006 Fly Ash Western Bituminous11.40 9/10/200404-007 Fly Ash Western Bituminous 12.74 6/13/2006 12.65 6/14/2006 12.82 9/1/200404-007 Fly Ash Western Bituminous 13.00 4/8/2004 12.80 9/1/200404-007 Fly Ash Western Bituminous12.83 9/10/200404-029 Fly Ash PRB Subbituminous 12.56 6/15/2006 12.27 6/16/2006 12.62 9/1/200404-029 Fly Ash PRB Subbituminous 12.37 4/8/2004 12.61 9/10/2004Page 2 of 4ID No. Sample Type Mercury Control Configuration Coal TypeSamplePrep10–15-MinpH10–15-MinpH Date 24-Hr pH24-Hr pHDateOvernightpHOvernightpH Date1 M KClpH1 M KClpH Date04-030 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 11.56 6/15/2006 11.30 6/16/200604-030 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 11.51 4/15/2004 11.54 8/31/200404-031 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 11.64 6/21/2006 11.25 6/22/2006 11.73 8/31/200404-031 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 11.60 4/15/200404-032 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 9.54 6/15/2006 10.52 6/16/2006 9.42 8/31/200404-032 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 9.67 4/15/200404-033 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 10.70 4/15/2004 10.98 8/31/200404-035 Fly Ash Fort Union Lignite 12.77 6/15/2006 12.74 6/16/2006 12.83 8/30/200404-035 Fly Ash Fort Union Lignite 12.68 6/9/200404-036Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal, ACI PrePrimary PCD Fort Union Lignite 12.79 6/15/2006 12.77 6/16/2006 12.82 8/30/200404-036Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal, ACI PrePrimary PCD Fort Union Lignite 12.64 6/9/200404-042 Fly Ash Gulf Coast Lignite 11.87 6/21/2006 11.31 6/22/200604-042 Fly Ash Gulf Coast Lignite 11.77 10/19/200404-043 Fly Ash Gulf Coast Lignite 11.82 6/21/2006 11.28 6/22/200604-043 Fly Ash Gulf Coast Lignite 11.48 6/9/200404-044 Fly Ash Gulf Coast Lignite 11.76 6/21/2006 11.27 6/22/200604-044 Fly Ash Gulf Coast Lignite 11.52 10/19/200404-054 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 8.48 4/20/2006 9.20 4/21/2006 9.43 8/30/200404-054 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 9.10 12/12/2005 9.59 12/13/200504-054 Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous 6.40 10/19/200404-067Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal, ACI PrePrimary PCD Fort Union Lignite 12.70 6/21/2006 12.60 6/22/200604-067Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal, ACI PrePrimary PCD Fort Union Lignite 12.80 11/5/200404-082 FGD Gypsum Eastern Bituminous 8.19 5/8/2006 7.72 5/9/200604-082 FGD Gypsum Eastern Bituminous 8.10 2/17/200504-083 FGD Gypsum Eastern Bituminous 8.19 5/8/2006 7.80 5/9/200604-083 FGD Gypsum Eastern Bituminous 8.10 2/17/200505-001 Fly Ash Fort Union Lignite 12.50 5/2/2006 12.51 5/3/200605-001 Fly Ash Fort Union Lignite 12.84 2/22/200505-002 FGD-SDA Fort Union Lignite 12.55 5/2/2006 12.50 5/3/200605-002 FGD-SDA Fort Union Lignite 12.85 2/22/200505-003Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal, ACIbefore SDA Fort Union Lignite 12.39 5/2/2006 12.29 5/3/200605-003Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal, ACIbefore SDA Fort Union Lignite 12.85 3/7/200505-004FGD-SDA + Enhancing Agent +Activated CarbonEnhancing Agent on Coal, ACIbefore SDA Fort Union Lignite 12.51 5/2/2006 12.54 5/3/200605-004FGD-SDA + Enhancing Agent +Activated CarbonEnhancing Agent on Coal, ACIbefore SDA Fort Union Lignite 13.06 3/7/200505-005 Fly Ash Fort Union Lignite 11.77 4/26/2006 11.57 4/27/200605-005 Fly Ash Fort Union Lignite 11.95 5/17/200505-009 FGD Gypsum Eastern Bituminous 8.68 5/8/2006 7.88 5/9/200605-009 FGD Gypsum Eastern Bituminous 8.83 8/25/200505-010 Fly Ash Eastern Bituminous 11.91 6/15/2006 11.72 6/16/200605-010 Fly Ash Eastern Bituminous 12.11 8/25/200505-013 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 9.00 4/20/2006 11.33 4/21/200605-013 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 9.05 11/3/2005Page 3 of 4ID No. Sample Type Mercury Control Configuration Coal TypeSamplePrep10–15-MinpH10–15-MinpH Date 24-Hr pH24-Hr pHDateOvernightpHOvernightpH Date1 M KClpH1 M KClpH Date05-017 Fly Ash + Enhancing AgentEnhancing Agent on Coal Fort Union Lignite 12.04 4/26/2006 11.77 4/27/200605-017 Fly Ash + Enhancing AgentEnhancing Agent on Coal Fort Union Lignite 12.19 8/25/200505-018 Fly Ash Eastern Bituminous 7.42 4/26/2006 8.49 4/27/200605-018 Fly Ash Eastern Bituminous 7.56 8/25/200505-019 FGD Filtercake Eastern Bituminous 7.90 5/8/2006 7.88 5/9/200605-019 FGD Filtercake Eastern Bituminous 8.07 11/3/200505-020 Fixated FGD Eastern Bituminous 12.10 5/8/2006 12.43 5/9/200605-020 Fixated FGD Eastern Bituminous 12.75 8/25/200505-023 Fly Ash + Activated CarbonPost-Primary PCD: High Fly AshContent Fort Union Lignite 11.35 4/20/2006 12.00 4/21/200605-023 Fly Ash + Activated CarbonPost-Primary PCD: High Fly AshContent Fort Union Lignite 11.65 11/3/200505-024 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 7.43 4/20/2006 11.41 4/21/200605-024 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 8.93 11/3/200505-025 Fly Ash + Activated CarbonPost-Primary PCD: High Fly AshContent Fort Union Lignite 11.53 4/20/2006 11.99 4/21/200605-025 Fly Ash + Activated CarbonPost-Primary PCD: High Fly AshContent Fort Union Lignite 11.67 11/3/200505-038 Fly Ash Fort Union Lignite 11.67 4/20/2006 11.73 4/21/200605-038 Fly Ash Fort Union Lignite 12.03 12/7/200505-040 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 7.03 4/20/2006 11.36 4/21/200605-040 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 6.80 12/8/2005 11.74 12/9/200506-001 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 6.69 4/4/2006 11.44 4/5/200606-001 Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite 7.20 4/20/2006 11.37 4/21/2006Page 4 of 4

# APPENDIX L

CARBON FORMS DATAID No. Sample Type Mercury Control Configuration Coal Type Dominant Carbon Form02-002 Fly Ash + Activated Carbon Post-Primary PCD Eastern BituminousAnisotropic Coke02-004 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous Isotropic Coke02-007 Fly Ash + Activated Carbon Post-Primary PCD Eastern BituminousAnisotropic Coke02-070 Fly Ash Eastern Bituminous Unburned Coal02-076 Fly Ash South American BituminousAnisotropic Coke03-004 Fly Ash Eastern Bituminous Inertinite03-005 Fly Ash Eastern Bituminous Unburned Coal03-006 Fly Ash Eastern Bituminous Unburned Coal03-007 Fly Ash Eastern Bituminous Vitrinite03-008 Fly Ash South American Bituminous Unburned Coal03-016 Fly Ash Fort Union Lignite Vitrinite03-017 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite Inertinite03-018 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union LigniteAnisotropic Coke03-019 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite Inertinite03-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB SubbituminousAnisotropic Coke03-061 Fly Ash PRB Subbituminous Isotropic Coke03-062 Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite Unburned Coal03-063 Fly Ash Eastern Bituminous Vitrinite03-078 Fly Ash Fort Union Lignite Vitrinite03-079 Fly Ash Fort Union LigniteAnisotropic Coke03-080 Fly Ash Fort Union Lignite Isotropic Coke03-083 Fly Ash Eastern Bituminous Unburned CoalPage 1 of 1

# APPENDIX M

LEACHATE DATAID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH99-188 FGD-SDAPRBSubbituminous18-HourSGLP 3.5 0.37 116 <2 <0.01 27.0 65.8 12.1499-188 FGD-SDAPRBSubbituminous18-HourSGLP <10 <10 105 <10 16.4 29.9 12.3399-188 FGD-SDAPRBSubbituminous 30-Day LTL 2.6 0.58 215 <2 <0.01 <2 53.5 11.4199-188 FGD-SDAPRBSubbituminous 60-Day LTL 2.2 0.59 223 <2 0.043 <2 53.1 11.4302-002Fly Ash + ActivatedCarbon Post-Primary PCDEasternBituminous18-HourSGLP <0.01 4.0002-002Fly Ash + ActivatedCarbon Post-Primary PCDEasternBituminous TCLP #1 0.01 4.5402-003Fly Ash + ActivatedCarbon Post-Primary PCDEasternBituminous18-HourSGLP <0.01 4.5302-003Fly Ash + ActivatedCarbon Post-Primary PCDEasternBituminous TCLP #1 <0.01 4.7602-004Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous18-HourSGLP <0.01 12.0002-004Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous 30-Day LTL <0.01 11.9502-004Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous 60-Day LTL <0.01 11.9002-004Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous TCLP #2 <0.01 5.5102-005Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous18-HourSGLP <0.01 11.0802-005Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous 30-Day LTL <0.01 11.8402-005Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous 60-Day LTL 0.01 11.8502-005Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous TCLP #2 <0.01 6.5302-006Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous18-HourSGLP 3.5 <0.2 560 <2 0.064 <2 57.1 11.57Page 1 of 13ID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH02-006Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous TCLP #2 <0.01 6.5602-007Fly Ash + ActivatedCarbon Post-Primary PCDEasternBituminous18-HourSGLP <0.01 4.0602-069Fly Ash + ActivatedCarbon Post-Primary PCDEasternBituminous18-HourSGLP 0.03 9.4802-069Fly Ash + ActivatedCarbon Post-Primary PCDEasternBituminous TCLP #2 0.07 3.7902-070 Fly AshEasternBituminous18-HourSGLP 0.01 10.5502-070 Fly AshEasternBituminous TCLP #2 0.03 3.5602-071Fly Ash + ActivatedCarbon Post-Primary PCDEasternBituminous18-HourSGLP 0.01 9.8902-071Fly Ash + ActivatedCarbon Post-Primary PCDEasternBituminous TCLP #2 <0.01 4.0602-072 Fly AshEasternBituminous18-HourSGLP 0.02 10.8102-072 Fly AshEasternBituminous TCLP #2 0.02 3.5402-073 Fly AshEasternBituminous18-HourSGLP 0.05 12.6702-073 Fly AshEasternBituminous TCLP #2 0.02 4.9702-074 Fly AshEasternBituminous18-HourSGLP 0.01 12.4002-074 Fly AshEasternBituminous TCLP #2 0.01 4.8802-076 Fly AshSouth AmericanBituminous18-HourSGLP 0.016 11.1802-076 Fly AshSouth AmericanBituminous TCLP #2 <0.01 3.8903-004 Fly AshEasternBituminous18-HourSGLP 7.7 6.27 <2 <0.01 50.0 16.7 5.54Page 2 of 13ID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH03-004 Fly AshEasternBituminous18-HourSGLP 9.3 1.10 9.8 <0.001 31.0 26.0 6.3003-004 Fly AshEasternBituminous18-HourSGLP 10.5 1.81 11 <2 0.019 80.6 31.8 6.3003-004 Fly AshEasternBituminous 60-Day LTL 118 1.11 10.1 <2 0.012 8.1 125 7.2903-005 Fly AshEasternBituminous18-HourSGLP 5.9 8.08 <2 <0.01 60.0 13.2 4.9803-005 Fly AshEasternBituminous18-HourSGLP <0.01 5.0003-005 Fly AshEasternBituminous18-HourSGLP 2.9 7.36 <2 <2 0.019 66.4 16.1 5.0003-005 Fly AshEasternBituminous 60-Day LTL 6.5 7.22 <2 <2 0.239 70.0 48.9 5.5903-006 Fly AshEasternBituminous18-HourSGLP 12.5 3.58 8.8 <2 <0.01 58.0 49.6 6.2203-006 Fly AshEasternBituminous18-HourSGLP 10.0 3.00 7.4 <0.001 50.0 49.0 6.2203-006 Fly AshEasternBituminous18-HourSGLP 19.2 4.31 <2 <0.01 40.0 48.5 6.4103-006 Fly AshEasternBituminous 60-Day LTL 110 1.37 7.5 <2 0.06 18.2 212 7.2003-007 Fly AshEasternBituminous18-HourSGLP 20.0 7.83 <2 <0.01 50.0 36.6 4.7103-007 Fly AshEasternBituminous18-HourSGLP 16.2 7.58 2.0 <2 <0.01 73.5 36.0 4.9703-007 Fly AshEasternBituminous18-HourSGLP 15.0 7.30 1.4 <0.001 75.0 29.0 4.9703-007 Fly AshEasternBituminous 60-Day LTL 10.6 6.70 <2 <2 <0.01 70.0 86.9 5.5503-008 Fly AshSouth AmericanBituminous18-HourSGLP <0.01 11.6803-008 Fly AshSouth AmericanBituminous TCLP #2 0.034 4.11Page 3 of 13ID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH03-009Fly Ash + ActivatedCarbon Pre-Primary PCDSouth AmericanBituminous18-HourSGLP <0.01 11.7103-009Fly Ash + ActivatedCarbon Pre-Primary PCDSouth AmericanBituminous TCLP #2 <0.01 4.2003-010Fly Ash + ActivatedCarbon Pre-Primary PCDSouth AmericanBituminous18-HourSGLP <0.01 10.7103-010Fly Ash + ActivatedCarbon Pre-Primary PCDSouth AmericanBituminous TCLP #2 <0.01 3.8003-060Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous18-HourSGLP 2.7 <0.2 <50 <2 <0.01 8.4 12.1503-060Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous18-HourSGLP <2 0.22 54.1 <2 0.025 23.1 16.5 12.2103-060Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous 30-Day LTL <2 <0.2 6.3 3.0 <0.01 4.5 8.5 12.4603-060Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous 60-Day LTL <0.01 12.3803-060Fly Ash + ActivatedCarbon Pre-Primary PCDPRBSubbituminous 60-Day LTL <2 <0.2 10.7 2.4 0.068 <2 11.4 12.3803-061 Fly AshPRBSubbituminous18-HourSGLP 2.0 <2 <2 <0.01 5.4 12.4003-061 Fly AshPRBSubbituminous18-HourSGLP <2 <0.2 15.5 <2 0.018 2.5 14.2 12.4903-061 Fly AshPRBSubbituminous 30-Day LTL <2 <0.2 3.0 3.6 <0.01 4.1 9.8 12.6303-061 Fly AshPRBSubbituminous 60-Day LTL <2 <0.2 3.2 8.5 0.325 <2 13.9 12.5803-062Fly Ash + ActivatedCarbon Pre-Primary PCD Fort Union Lignite18-HourSGLP 6.6 0.34 80.0 <2 <0.01 68.0 12.5903-062Fly Ash + ActivatedCarbon Pre-Primary PCD Fort Union Lignite18-HourSGLP 6.0 0.45 103 <2 <0.01 10.7 81.1 12.6003-062Fly Ash + ActivatedCarbon Pre-Primary PCD Fort Union Lignite18-HourSGLP <4 <0.3 99.0 <0.001 <4 68.0 12.6003-062Fly Ash + ActivatedCarbon Pre-Primary PCD Fort Union Lignite 30-Day LTL <2 <0.2 3.6 <2 <0.01 <2 <2 12.34Page 4 of 13ID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH03-062Fly Ash + ActivatedCarbon Pre-Primary PCD Fort Union Lignite 60-Day LTL 5.2 <0.2 5.2 <2 <0.01 <2 3.8 12.4003-063 Fly AshEasternBituminous18-HourSGLP 67.8 <0.2 <2 <0.01 29.1 11.6103-063 Fly AshEasternBituminous18-HourSGLP 52.0 <0.3 38.8 <0.001 <4 29.0 11.7003-063 Fly AshEasternBituminous18-HourSGLP 60.2 0.57 43.5 <2 <0.01 3 31.6 11.7003-063 Fly AshEasternBituminous 30-Day LTL 37.7 0.64 38.6 <2 <0.01 <2 42.6 11.4903-063 Fly AshEasternBituminous 60-Day LTL 36.1 0.61 38.8 <2 0.038 <2 37.4 11.3603-065 FGD GypsumEasternBituminous18-HourSGLP <2 <0.2 <2 <2 <0.01 <2 3.3 7.8003-065 FGD GypsumEasternBituminous 60-Day LTL <2 <0.2 <2 <2 <0.01 10.1 2.7 7.9903-067 FGD SlurryEasternBituminous18-HourSGLP <4 <0.3 <1 <0.001 0.047 15.0 65.0 8.0203-078 Fly Ash Fort Union Lignite18-HourSGLP 95.1 0.43 150 <2 <0.01 151 11.3203-078 Fly Ash Fort Union Lignite18-HourSGLP 90.5 4.47 166 <2 <0.01 11.1 149 NT03-079 Fly Ash Fort Union Lignite18-HourSGLP 75.7 0.37 150 <2 <0.01 60.4 11.8203-079 Fly Ash Fort Union Lignite18-HourSGLP 74.8 3.71 174 <2 <0.01 7.4 89.4 11.9103-079 Fly Ash Fort Union Lignite 30-Day LTL 45.3 4.23 265 <2 <0.01 <2 40.1 11.6003-079 Fly Ash Fort Union Lignite 60-Day LTL 59.8 3.96 250 <2 0.049 <2 38.9 11.5603-079 Fly Ash Fort Union Lignite 60-Day LTL 49.3 4.40 277 <2 <0.01 <2 37.7 11.6003-079 Fly Ash Fort Union Lignite 60-Day LTL <0.01 11.6003-080 Fly Ash Fort Union Lignite18-HourSGLP 44.6 1.57 90.0 <2 0.011 <2 75.1 12.0403-080 Fly Ash Fort Union Lignite 30-Day LTL 35.2 1.97 134 <2 0.113 <2 23.8 11.7803-080 Fly Ash Fort Union Lignite 60-Day LTL 29.2 2.06 110 <2 0.041 <2 22.7 11.8003-080 Fly Ash Fort Union Lignite 60-Day LTL 28.7 2.14 135 <2 <0.01 <2 24.1 11.84Page 5 of 13ID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH03-081 Fly Ash Fort Union Lignite18-HourSGLP 140 3.75 120 <2 0.083 <2 240 10.9503-081 Fly Ash Fort Union Lignite 30-Day LTL 232 6.02 264 <2 0.013 <2 112 11.3403-081 Fly Ash Fort Union Lignite 60-Day LTL 226 5.38 230 <2 0.019 <2 98.2 11.2503-081 Fly Ash Fort Union Lignite 60-Day LTL 0.017 11.3103-081 Fly Ash Fort Union Lignite 60-Day LTL 223 5.60 273 <2 0.124 <2 91.6 11.3103-082 FGD FiltercakeEasternBituminous18-HourSGLP 3.7 <0.2 <2 <2 0.404 7.4 71.2 8.3903-082 FGD FiltercakeEasternBituminous 30-Day LTL <0.01 7.6903-082 FGD FiltercakeEasternBituminous 30-Day LTL 3.5 0.83 <2 <2 <0.01 32.1 55.2 7.6903-082 FGD FiltercakeEasternBituminous 60-Day LTL <2 0.47 <2 <2 <0.01 25.4 45.3 7.5703-083 Fly AshEasternBituminous18-HourSGLP 48.0 <0.3 9.1 <0.001 <4 46.0 9.2103-083 Fly AshEasternBituminous18-HourSGLP 54.3 2.92 10.7 <2 <0.01 4.4 49.9 9.2103-083 Fly AshEasternBituminous18-HourSGLP 97.3 <0.2 <2 <0.01 44.1 9.4003-084 Fixated FGDEasternBituminous18-HourSGLP 4.9 0.44 4.7 14.3 0.289 <2 2.7 12.3403-084 Fixated FGDEasternBituminous 30-Day LTL <0.01 11.8703-084 Fixated FGDEasternBituminous 30-Day LTL 5.2 0.66 3.1 <2 <0.01 4.0 2.4 11.8703-084 Fixated FGDEasternBituminous 60-Day LTL <2 0.48 2.4 <2 <0.01 3.5 2.0 11.9403-084 Fixated FGDEasternBituminous 60-Day LTL <2 0.50 2.5 <2 <0.01 3.7 <2 11.9403-085 Fly AshEasternBituminous18-HourSGLP <0.01 10.7503-085 Fly AshEasternBituminous18-HourSGLP 250 2.57 21.3 <2 <0.01 3.2 90.2 10.87Page 6 of 13ID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH03-085 Fly AshEasternBituminous18-HourSGLP 250 <0.3 19.5 <0.001 <4 75.0 10.8703-085 Fly AshEasternBituminous18-HourSGLP 266 0.28 <2 <0.01 77.6 10.9103-087 Fixated FGDEasternBituminous18-HourSGLP 7.0 0.43 3.0 6.6 0.237 <2 2.1 12.0703-087 Fixated FGDEasternBituminous 30-Day LTL 24.0 0.30 2.2 <2 <0.01 <2 3.4 11.3103-087 Fixated FGDEasternBituminous 60-Day LTL 19.1 0.37 3.3 <2 <0.01 2.1 <2 11.5003-088 Fly AshEasternBituminous18-HourSGLP 18.4 4.93 110 <2 0.029 <2 76.4 11.7703-088 Fly AshEasternBituminous 30-Day LTL 23.0 7.64 160 <2 <0.01 5.4 15.5 11.2103-088 Fly AshEasternBituminous 60-Day LTL 23.4 8.30 180 <2 <0.01 5.6 19.0 11.0303-089 FGD GypsumEasternBituminous18-HourSGLP <2 0.46 <2 <2 <0.01 <2 9.4 7.6203-089 FGD GypsumEasternBituminous 60-Day LTL <2 <0.2 <2 <2 <0.01 12.6 8.2 7.8504-003 Fly AshEasternBituminous18-HourSGLP 188 0.56 48.8 <2 <0.01 <2 412 9.6704-003 Fly AshEasternBituminous 30-Day LTL 305 0.88 69.3 <2 0.104 <2 489 9.3804-003 Fly AshEasternBituminous 60-Day LTL 282 0.71 70.6 <2 <0.01 <2 492 9.0804-003 Fly AshEasternBituminous 60-Day LTL 336 0.77 70.0 <2 <0.01 <2 514 9.1304-004 Fly AshEasternBituminous18-HourSGLP 136 0.70 70.0 <2 <0.01 <2 166 10.7504-004 Fly AshEasternBituminous 30-Day LTL 135 1.02 98.1 <2 <0.01 <2 186 10.5704-004 Fly AshEasternBituminous 60-Day LTL 140 0.84 100 <2 0.077 <2 180 10.69Page 7 of 13ID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH04-006 Fly AshWesternBituminous18-HourSGLP <0.01 11.5704-006 Fly AshWesternBituminous18-HourSGLP 12.3 0.28 34.6 <2 <0.01 <2 160 11.6104-006 Fly AshWesternBituminous 30-Day LTL 3.4 0.36 49.2 <2 0.076 <2 111 11.3704-006 Fly AshWesternBituminous 60-Day LTL 7.3 0.33 52.8 <2 0.087 <2 76.2 11.3104-007 Fly AshWesternBituminous18-HourSGLP 10.7 <2 120 <2 0.021 <2 265 12.8104-007 Fly AshWesternBituminous 30-Day LTL <2 <0.2 7.3 2.2 0.035 10.6 26.7 12.5404-007 Fly AshWesternBituminous 60-Day LTL <2 <0.2 6.7 <2 <0.01 10.0 17.4 12.5204-029 Fly AshPRBSubbituminous18-HourSGLP <2 <0.2 24.1 <2 0.023 <2 2.1 12.0904-029 Fly AshPRBSubbituminous 30-Day LTL <2 <0.2 5.1 <2 <0.01 4.0 <2 12.3604-029 Fly AshPRBSubbituminous 60-Day LTL <2 <0.2 2.3 <2 <0.01 4.8 <2 12.4504-030Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite18-HourSGLP 26.9 1.40 399 <2 <0.01 <2 222 11.6504-030Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 30-Day LTL 8.1 1.86 640 <2 <0.01 5.6 53.2 11.7804-030Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 60-Day LTL 10.6 2.35 670 <2 <0.01 3.3 63.4 11.6404-031Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite18-HourSGLP 23.2 1.49 410 <2 0.012 <2 177 11.7004-031Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 30-Day LTL 9.6 1.95 650 <2 <0.01 4.4 54.4 11.8204-031Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 60-Day LTL 11.5 2.34 680 <2 0.028 2.9 60.3 11.7104-032Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite18-HourSGLP 28.0 1.24 333 <2 <0.01 <2 215 11.00Page 8 of 13ID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH04-033Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite18-HourSGLP 31.1 1.32 351 <2 <0.01 <2 156 11.4104-033Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 30-Day LTL 10.1 1.99 580 <2 <0.01 5.8 64.8 11.5504-033Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 60-Day LTL 10.4 2.46 620 <2 <0.01 4.7 71.0 11.4304-035 Fly Ash Fort Union Lignite18-HourSGLP <2 <0.2 55.8 <2 0.081 <2 17.8 12.6004-035 Fly Ash Fort Union Lignite 30-Day LTL <2 <0.2 <2 <2 0.02 9.6 <2 12.6504-035 Fly Ash Fort Union Lignite 60-Day LTL <2 <0.2 2.1 <2 <0.01 6.2 <2 12.5404-036Fly Ash + EnhancingAgent + ActivatedCarbonEnhancing Agenton Coal, ACI PrePrimary PCD Fort Union Lignite18-HourSGLP <2 0.27 67.6 3.0 0.016 <2 19.9 12.5404-036Fly Ash + EnhancingAgent + ActivatedCarbonEnhancing Agenton Coal, ACI PrePrimary PCD Fort Union Lignite18-HourSGLP <0.01 12.5704-036Fly Ash + EnhancingAgent + ActivatedCarbonEnhancing Agenton Coal, ACI PrePrimary PCD Fort Union Lignite 30-Day LTL <2 <0.2 <2 <2 <0.01 8.2 <2 12.6104-036Fly Ash + EnhancingAgent + ActivatedCarbonEnhancing Agenton Coal, ACI PrePrimary PCD Fort Union Lignite 60-Day LTL <2 <0.2 2.1 <2 <0.01 5.4 <2 12.5904-054Fly Ash + ActivatedCarbon Post-Primary PCDEasternBituminous18-HourSGLP 842 1.87 17.3 <2 <0.01 5.6 8620 NT04-067Fly Ash + EnhancingAgent + ActivatedCarbonEnhancing Agenton Coal, ACI PrePrimary PCD Fort Union Lignite18-HourSGLP 15.2 0.39 <2 2.2 <0.01 21.0 47.2 12.5004-082 FGD GypsumEasternBituminous18-HourSGLP <2 0.33 <2 <2 <0.01 28.4 12.5 7.4204-082 FGD GypsumEasternBituminous18-HourSGLP <0.01 8.1704-083 FGD GypsumEasternBituminous18-HourSGLP <2 0.25 <2 <2 <0.01 23.3 18.7 8.0205-001 Fly Ash Fort Union Lignite18-HourSGLP 3.0 0.24 45.3 <2 <0.01 43.6 12.9 12.42Page 9 of 13ID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH05-001 Fly Ash Fort Union Lignite 30-Day LTL <4 <0.3 153 <0.001 <0.01 <4 14.0 12.1105-001 Fly Ash Fort Union Lignite 30-Day LTL 2.1 0.26 132 <2 0.016 <2 15.6 12.3205-001 Fly Ash Fort Union Lignite 60-Day LTL 2.5 0.22 152 <2 0.011 <2 18.0 12.3905-002 FGD-SDA Fort Union Lignite18-HourSGLP 2.1 0.22 34.6 <2 <0.01 39.1 11.3 12.4005-002 FGD-SDA Fort Union Lignite 30-Day LTL <4 <0.3 126 <0.001 <0.01 <4 12.0 12.2305-002 FGD-SDA Fort Union Lignite 30-Day LTL 3.3 <0.2 113 <2 0.095 <2 65.2 12.4105-002 FGD-SDA Fort Union Lignite 60-Day LTL 2.3 0.20 132 <2 0.013 <2 14.4 12.4705-003Fly Ash + EnhancingAgent + ActivatedCarbonEnhancing Agenton Coal, ACIbefore SDA Fort Union Lignite18-HourSGLP 7.2 0.30 49.9 <2 <0.01 25.2 34.2 12.3405-003Fly Ash + EnhancingAgent + ActivatedCarbonEnhancing Agenton Coal, ACIbefore SDA Fort Union Lignite 30-Day LTL <4 <0.3 133 <0.001 <0.05 <4 25.0 12.2105-003Fly Ash + EnhancingAgent + ActivatedCarbonEnhancing Agenton Coal, ACIbefore SDA Fort Union Lignite 30-Day LTL 6.4 <0.2 123 <2 0.061 <2 27.2 12.3905-003Fly Ash + EnhancingAgent + ActivatedCarbonEnhancing Agenton Coal, ACIbefore SDA Fort Union Lignite 60-Day LTL 7.5 <0.2 133 <2 0.016 <2 30.3 12.4805-003Fly Ash + EnhancingAgent + ActivatedCarbonEnhancing Agenton Coal, ACIbefore SDA Fort Union Lignite 60-Day LTL 6.9 <0.2 134 <2 0.013 <2 29.8 12.4905-004FGD-SDA +Enhancing Agent +Activated CarbonEnhancing Agenton Coal, ACIbefore SDA Fort Union Lignite18-HourSGLP 4.3 0.20 21.8 <2 <0.01 29.3 24.3 12.4305-004FGD-SDA +Enhancing Agent +Activated CarbonEnhancing Agenton Coal, ACIbefore SDA Fort Union Lignite 30-Day LTL <4 <0.3 78.0 <0.001 <0.02 <4 12.0 12.4105-004FGD-SDA +Enhancing Agent +Activated CarbonEnhancing Agenton Coal, ACIbefore SDA Fort Union Lignite 30-Day LTL 3.6 <0.2 67.7 <2 <0.01 <2 13.2 12.5505-004FGD-SDA +Enhancing Agent +Activated CarbonEnhancing Agenton Coal, ACIbefore SDA Fort Union Lignite 60-Day LTL 3.8 <0.2 87.7 <2 0.012 <2 17.0 12.60Page 10 of 13ID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH05-005 Fly Ash Fort Union Lignite18-HourSGLP 134 2.79 137 <2 <0.01 15.5 123 11.6505-005 Fly Ash Fort Union Lignite18-HourSGLP <0.01 11.7305-005 Fly Ash Fort Union Lignite 30-Day LTL <0.01 11.6105-005 Fly Ash Fort Union Lignite 30-Day LTL 101 2.48 179 <2 <0.01 <2 51.6 11.8605-005 Fly Ash Fort Union Lignite 60-Day LTL 140 <0.3 166 <0.001 <4 15.0 11.8205-005 Fly Ash Fort Union Lignite 60-Day LTL 160 2.65 183 <2 <0.01 <2 38.5 11.8205-005 Fly Ash Fort Union Lignite 60-Day LTL <0.01 11.8305-005 Fly Ash Fort Union Lignite 60-Day LTL <0.01 11.8405-009 FGD GypsumEasternBituminous18-HourSGLP <4 <0.3 <1 <0.001 <0.01 <4 <4 7.8305-010 Fly AshEasternBituminous18-HourSGLP 41.0 <0.3 19.4 <0.001 <0.01 <4 160 11.7905-013Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite18-HourSGLP 30.4 1.29 112 <2 <0.01 15.8 498 11.4505-013Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 30-Day LTL 30.4 1.08 159 <2 <0.01 5.9 312 11.6605-013Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 60-Day LTL 27.3 1.14 156 <2 <0.01 4.1 199 11.6105-017Fly Ash + EnhancingAgentEnhancing Agenton Coal Fort Union Lignite18-HourSGLP <0.01 11.9405-017Fly Ash + EnhancingAgentEnhancing Agenton Coal Fort Union Lignite 30-Day LTL <0.01 11.6905-017Fly Ash + EnhancingAgentEnhancing Agenton Coal Fort Union Lignite 30-Day LTL 46.3 2.40 203 <2 <0.01 2.8 97.0 11.8905-017Fly Ash + EnhancingAgentEnhancing Agenton Coal Fort Union Lignite 60-Day LTL <0.01 11.9905-017Fly Ash + EnhancingAgentEnhancing Agenton Coal Fort Union Lignite 60-Day LTL 73.0 <0.3 182 <0.001 <4 <4 12.0005-017Fly Ash + EnhancingAgentEnhancing Agenton Coal Fort Union Lignite 60-Day LTL 95.3 2.55 206 <2 0.02 <2 50.9 12.0005-017Fly Ash + EnhancingAgentEnhancing Agenton Coal Fort Union Lignite 60-Day LTL 95.9 2.68 211 <2 0.012 <2 49.2 12.01Page 11 of 13ID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH05-017Fly Ash + EnhancingAgentEnhancing Agenton Coal Fort Union Lignite 60-Day LTL <0.01 12.0105-018 Fly AshEasternBituminous18-HourSGLP 150 <0.3 11.1 <0.001 0.022 <4 280 8.9605-019 FGD FiltercakeEasternBituminous18-HourSGLP <4 <0.3 <1 <0.001 0.476 6.1 41.0 8.1005-023Fly Ash + ActivatedCarbonPost-PrimaryPCD: High Fly AshContent Fort Union Lignite18-HourSGLP 14.5 1.01 168 <2 <0.01 11.8 145 11.8505-023Fly Ash + ActivatedCarbonPost-PrimaryPCD: High Fly AshContent Fort Union Lignite 30-Day LTL 8.1 0.75 134 <2 <0.01 4.9 65.1 12.0505-023Fly Ash + ActivatedCarbonPost-PrimaryPCD: High Fly AshContent Fort Union Lignite 60-Day LTL 9.1 0.72 138 <2 <0.01 5.0 72.2 12.0905-024Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite18-HourSGLP 24.6 1.50 141 <2 <0.01 20.3 343 11.5105-024Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 30-Day LTL 17.9 1.13 173 <2 <0.01 5.2 75.9 11.6705-024Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 60-Day LTL 14.0 1.16 167 <2 <0.01 4.0 73.2 11.6805-025Fly Ash + ActivatedCarbonPost-PrimaryPCD: High Fly AshContent Fort Union Lignite18-HourSGLP 16.3 1.49 153 <2 <0.01 12.2 147 11.8805-025Fly Ash + ActivatedCarbonPost-PrimaryPCD: High Fly AshContent Fort Union Lignite 30-Day LTL 9.9 1.06 147 <2 <0.01 5.4 100 12.0405-025Fly Ash + ActivatedCarbonPost-PrimaryPCD: High Fly AshContent Fort Union Lignite 60-Day LTL 11.7 0.90 133 <2 <0.01 5.3 114 12.0705-038 Fly Ash Fort Union Lignite18-HourSGLP 8.1 1.10 169 <2 <0.01 18.9 60.5 11.8505-038 Fly Ash Fort Union Lignite 30-Day LTL 2.4 0.58 92.0 <2 <0.01 5.3 20.1 12.0005-038 Fly Ash Fort Union Lignite 60-Day LTL <2 0.67 88.6 <2 <0.01 5.2 26.8 12.09Page 12 of 13ID No. Sample TypeHg ControlConfiguration Coal TypeLeachateTestAs(μg/L)Cd(μg/L)Cr(μg/L)Pb(μg/L)Hg(μg/L)Ni(μg/L)Se(μg/L)LeachatepH05-040Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite18-HourSGLP 20.9 1.35 112 <2 <0.01 19.4 161 11.4705-040Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 30-Day LTL 17.0 0.96 152 <2 <0.01 5.6 47.7 11.5505-040Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 60-Day LTL 15.6 1.08 155 <2 <0.01 3.9 45.2 11.5406-001Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite18-HourSGLP 20.2 0.99 119 <2 <0.01 23.4 99.3 11.3806-001Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite18-HourSGLP 21.3 1.01 120 <2 <0.01 22.8 101 11.3906-001Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 30-Day LTL 18.6 0.85 166 <2 <0.01 7.1 66.4 11.5206-001Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 60-Day LTL 17.5 0.89 160 <2 <0.01 5.1 46.1 11.4506-001Fly Ash + ActivatedCarbon Post-Primary PCD Fort Union Lignite 60-Day LTL 17.7 0.85 157 <2 <0.01 4.9 49.9 11.49Page 13 of 13

# APPENDIX N

MERCURY AND AIR TOXIC ELEMENT

LEACHING FROM COAL COMBUSTION

BY-PRODUCTS

# MERCURY AND AIR TOXIC ELEMENT

LEACHING FROM COAL COMBUSTION

BY-PRODUCTS

Topical Report

Ms. Lynn Brickett

U.S. Department of Energy National Energy Technology Laboratory

626 Cochrans Mill Road PO Box 10940, MS 922-273C Pittsburgh, PA 15236-0940

Cooperative Agreement No. DE-FC26-03NT41727

Prepared by:

Debra F. Pflughoeft-Hassett

David J. Hassett Tera D. Buckley

Loreal V. Heebink

Erick J. Zacher

Energy & Environmental Research Center University of North Dakota

PO Box 9018 Grand Forks, ND 58202-9018

2005-EERC-08-08 August 2005EERC DISCLAIMER

LEGAL NOTICE This research report was prepared by the Energy & Environmental Research Center (EERC), an agency of the Univ ersity of North Dakota, as an account of work sponsored by the U.S. Department of Ener gy (DOE), the Center for Air Toxic Metals ® , Cynergy, the Utility Solid Waste Activities Group, the North Dakota Industrial Commission, and Great River Energy. Because of the research nature of the work performed, neither the EERC nor any of its employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or re presents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or othe rwise does not necessarily consti tute or imply its endorsement or recommendation by the EERC.

DOE DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United

States Government. Neither the United States G overnment, nor any agency thereof, nor any of their employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not n ecessarily constitute or imply its endorsement, recommendation, or favoring by the United States G overnment or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

NDIC DISCLAIMER

This report was prepared by the Energy & Environmental Research Center (EERC) pursuant to an agreement partially funded by th e Industrial Commission of North Dakota, and neither the EERC nor any of its subcontractor s nor the North Dakota Industrial Commission nor any person acting on behalf of either:

(A) Makes any warranty or repr esentation, express or impl ied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or

(B) Assumes any liabilities with respect to the use of, or for damages resulting from the use of, any information, apparatus, method, or process disclosed in this report.

Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not n ecessarily constitute or imply its endorsement,recommendation, or favoring by the North Da kota Industrial Commission. The views and opinions of authors expressed here in do not necessarily state or reflect those of the North Dakota

Industrial Commission

ACKNOWLEDGMENT

This report was prepared with the support of DOE Nati onal Energy Technology Laboratory Cooperative Agreement No. DE -FC21-93MC30098. However, any opinions, findings, conclusions, or recommen dations expressed herein are t hose of the authors(s) and do not necessarily reflect the views of DOE.i TABLE OF CONTENTS

LIST OF FIGURES ................................................................................................................ ........ ii

LIST OF TABLES................................................................................................................. ........iii

EXECUTIVE SUMMARY ........................................................................................................... iv

INTRODUCTION ................................................................................................................... ....... 1

BACKGROUND ..................................................................................................................... ....... 2

OBJECTIVES..................................................................................................................... ............ 2

METHODS ........................................................................................................................ ............. 3

LEACHING RESULTS AND DISCUSSION................................................................................ 3 Mercury Leaching Results .................................................................................................... 5

Other Air Toxic Elem ent Leaching Results .......................................................................... 9

Arsenic....................................................................................................................... .. 9

Cadmium.................................................................................................................... 11

Chromium.................................................................................................................. 11

Lead .......................................................................................................................... . 14

Nickel........................................................................................................................ . 14

Selenium .................................................................................................................... 18

SUMMARY........................................................................................................................ .......... 20

REFERENCES ..................................................................................................................... ........ 20

Hg/ATE Project Sample Set and Analysis Status..........................................................Appendix A

Tables......................................................................................................................... ....Appendix B

Figures........................................................................................................................ ....Appendix Cii LIST OF FIGURES

1 Total mercury vs. short- and long-te rm leachable mercury: all fly ash – without mercury control and fly ash – with mercury control samples. The x-axis is reduced from 120 μg/g .................................................................................................................. ....... 5

2 Total mercury vs. short- and long-term leach able mercury: all available paired fly ash samples. One paired sample set has two fly ash – with mercury control samples ................. 6

3 Total mercury vs. SGLP leachable mercury: all available paired fly ash samples. One paired sample set has two fly ash – with mercury control samples........................................ 7

4 Total mercury vs. SGLP and TCLP leachable mercury: all available paired fly ash samples. One paired sample set has two fly Ash – with mercury control samples ................ 7

5 Total mercury vs. short- and long-term leach able mercury: all FGD material samples......... 8

6 Total arsenic vs. short- and long-te rm leachable arsenic: all fly ash – without mercury control and fly ash – with mercury control samples............................................................... 9

7 Total arsenic vs. SGLP leachable arsenic: all available paired fly ash samples................... 10

8 Total arsenic vs. short- and long-term leachab le arsenic: all FGD material samples. One sample had a total arsenic LLQ higher than the reported value of another sample.............. 10

9 Total cadmium vs. short- and long-term leachable cadmium: all fly ash – without mercury control and fly ash – with mercury control samples............................................... 11

10 Total cadmium vs. SGLP leachable cadmium: all available paired fly ash samples............ 12

11 Total cadmium vs. short- and long-term leach able cadmium: all FGD material samples.... 12

12 Total chromium vs. short- and long-te rm leachable chromium: all fly ash – without mercury control and fly ash – with mercury control samples. Several samples had a leachable chromium LLQ higher than the reported values of other samples ....................... 13

13 Total chromium vs. SGLP leachable chromium : all available paired fly ash samples. One paired sample set had a leachable chromi um LLQ higher than th e reported values of other samples ............................................................................................................... ..... 13

14 Total chromium vs. short- and long-term leachable chromium: all FGD material samples........................................................................................................................ .......... 14

15 Total lead vs. short- and long-term leachable lead: all fly ash – without mercury control and fly ash – with mercury control samples ......................................................................... 15

Continued. . .iii LIST OF FIGURES (Continued)

16 Total lead vs. SGLP leachable lead: a ll available paired fly ash samples ............................ 15

17 Total lead vs. short- and long-term leach able lead: all FGD material samples .................... 16

18 Total nickel vs. short- and long-te rm leachable nickel: all fly ash – without mercury control and fly ash – with mercury control samples. Several samples had a leachable nickel LLQ higher than the reported values of other samples. The x-axis is reduced from 300 μg/g .................................................................................................................. ..... 16

19 Total nickel vs. SGLP leachable nickel: all available paired fly ash samples. One paired sample set had a leachable nickel LLQ higher th an the reported values of other samples... 17

20 Total nickel vs. short- and long-term leach able nickel: all FGD material samples.............. 17

21 Total selenium vs. short- and long-term leachable selenium: all fly ash – without mercury control and fly ash – with mercury control samples. Th e x-axis is reduced from 450 μg/g. The y-axis is reduced from 9000 μg/g.................................................................. 18

22 Total selenium vs. SGLP leachable selenium : all available paired fly ash samples............. 19

23 Total selenium vs. short- and long-term leach able selenium: all FGD material samples..... 19

LIST OF TABLES

1 Fly Ash Sample Types and Descriptions................................................................................ 4

2 FGD Material Types and Descriptions ................................................................................... 4iv MERCURY AND AIR TOXIC ELEMENT LEA CHING FROM COAL COMBUSTION

BY-PRODUCTS

EXECUTIVE SUMMARY

Under this 3-year project, funded by the U.S. Department of Energy and industry, the Energy & Environmental Research Center (EERC) is evaluating the impact of mercury and other air toxic elements on the management of co al combustion by-products (CCBs). The EERC is measuring the release of mercur y and other air toxic elements from fly ash and flue gas desulfurization (FGD) material under different controlled labora tory conditions. One key release mechanism is being investigated in the laboratory is that of mercury a nd other air toxic element releases by direct leaching. The goa l of the leaching task was to develop a broad set of mercury and air toxic element leaching data on CCBs in order to determine the leachability of these elements from CCBs generated at existing syst ems and mercury emission control test systems. Tests of direct leachability have long been used to assess the environmental performance of CCBs, and the EERC has elected to apply short- and long-term batch le aching procedures to samples of fly ash and FGD materi al that have been assembled for this project. The project sample set includes samples of fly ash and FGD mate rial that were obtained from full-scale coalfired power plants operating unde r typical conditions and with no mercury control technologies being used. The sample set also includes fly ash samples and one FGD sample that were collected at pilot- and full-scale facilities while mercury control t echnologies were being tested.

Leaching data were assembled and presented in two formats: 1) a comparison of total elemental concentration with leachate concentrations for all samples without and with mercury controls for fly ash and separately for FGD mate rials and 2) a comparison of “paired” fly ash samples with a true baseline fly ash sample without mercury control and a test fly ash sample

with mercury control. Key conclusions drawn from the mercury leaching data are as follows:

• Total mercury content of samples generated both without and with mercury emission controls present and mercury leachat e concentrations did not correlate.

• Leachate mercury concentrations were independent of short-term leaching procedures

used.

• Leachate mercury concentrations have been found to be extremely low regardless of the total mercury content of the sample.

• Total mercury content of pa ired test fly ash samples with mercury control was consistently higher than the pa ired baseline fly ash sample without mercury control.

Leaching data for other air toxi c elements did not indicate any consistent increase in total elemental content where mercury control was in place. Leaching profiles tended to be sampledependent. Additional leaching work is planned to increase the data set for the other air toxic elements and specifically for FGD materials.1 MERCURY AND AIR TOXIC ELEMENT LEA CHING FROM COAL COMBUSTION

BY-PRODUCTS

INTRODUCTION

The stability of merc ury associated with coal combus tion by-products (CCBs) has become a prominent question as the coal-fired utility industry works to develop and test mercury emission controls that may consequently incr ease the mercury associated with CCBs. The reasons for evaluating the release of mercury from CCBs are 1) to determine if mercury captured

on CCBs is stable or if it will be released, thus negating th e purpose of the removal of the mercury from the emissions, and 2) to aid util ities in determining and understanding potential changes in CCBs associated with mercur y control and associated CCB management.

Under this 3-year project, funded by the U.S. Department of Energy (DOE) and industry, the Energy & Environmental Resear ch Center (EERC) is evaluating the impact of mercury and other air toxic elements on the management of CCBs. The EERC is measuring the release of mercury and other air toxic elements under diffe rent controlled laboratory conditions and investigating the release of these same air toxic el ements in select field settings. Results will be used to determine if mercury release from CCBs, both as curre ntly produced and as produced with mercury and other emission controls in place, will potentially impact CCB management practices.

Laboratory tasks were designe d to address three primary pot ential release mechanisms for mercury over the life cycle of CCBs in a variet y of management scenarios. These release

mechanisms are:

1. Direct leachability of air t oxic constituents from CCBs.

2. Vapor release of mercury from CCBs at ambient and elevated temperatures.

3. Biologically mediated leachability and vapor release of mercury and other air toxic

elements from CCBs.

This report focuses on the results generated from the assessment of the direct leachability of mercury and other air toxic elements from CCBs . Tests of direct leacha bility have long been

used to assess the environmenta l performance of CCBs as well as other materials, by-products, and wastes for both organic and inorganic constituen ts. In this project, inorganic constituents, and especially air toxic elements were the fo cus. The air toxic elements included in the evaluations were mercury, arsenic, cadmium, chro mium, lead, nickel, and selenium. All of these elements have been found to be present on CCBs and to exhibit leachability under various conditions. This report is a preliminary summary of leaching results fo r the overall project entitled “Mercury and Air Toxic Element Impact s of Coal Combustion By-Product Disposal and

Utilization.”2 BACKGROUND

Leaching tests have been applied to CCBs as the primary means of assessing the potential for constituents present in CCBs to be released to the environment when these materials are placed in the environment. Over the last nearly 28 years, researchers at the EERC have leached a very large number of various CCBs. Many groups have worked to develop appropriate leaching tests for a variety of materials including CCBs , understand leaching mechanisms of various materials, and assemble leachate data sets. Ki m (1) and Sorini (2) published summaries of available leaching methods, and Kim (3) publishe d results of extensive leaching studies of CCBs. Even though a broad variety of leaching tests of varying type s (batch, serial batch, flowaround, flow-through, etc. [1, 2]) are published, the EERC has concluded that an appropriate leaching test for the assessment of the potential fo r environmental impact of CCBs must meet the following criteria if it is to stand up to legal and scientific scrutiny:

• The test must take into account any reactivity or unusual properties of the material being leached.

• The test must as closely as possible utili ze a leaching solution that mimics the leaching solution most likely to contact the mate rial in its use or disposal setting.

• If the ash is reactive with water, the test must take this into account by allowing the hydration reactions to occur during the course of the leaching test. This necessitates the use of long-term leaching (LTL).

The EERC developed a test that meets these cr iteria (4). The test is referred to as the synthetic groundwater leaching procedure (SGL P) and generally includes an 18-hour batch leaching test and two longer-term leaching tests. 30- and 60-day leaching times are recommended for the long-term tests.

OBJECTIVES

The goal of the leaching task was to devel op a broad set of mercury and air toxic element leaching data on CCBs in order to determine th e leachability of these elements from CCBs generated at existing systems and mercury emi ssion control test systems. Supporting objectives

were to:

• Select and apply one or more appropriate laboratory leaching methods to evaluate the potential for release of mercury and ot her air toxic elements from CCBs under

conditions that are relevant to ma nagement options applied to CCBs.

• Develop leaching data on “paired” sample s from systems where baseline and test samples were available.

• Draw conclusions about the mobility of these elements, especially mercury, that may impact choices for CCB management options.3 METHODS

A report entitled “Laboratory Methods for the Evaluation of Potential Release of Mercury from Coal Utilization By-Products” was published in April 2005 under separate cover for this project. A discussion of methods available and th e justification fo r method selection is included in detail in that report and is not replicated in this repo rt. The leaching tests performed on the samples in this project were the toxicity char acteristic leaching procedure (TCLP) (5), SGLP, and LTL with 30- and 60-day equilibration periods.

Under this project, the EERC is participating in an interl aboratory comparative study of leaching procedures and has provided a sample of regional fly ash for inclusion in the comparative study. Participants in that st udy are the DOE Nati onal Energy Technology Laboratory (NETL), the EERC, the University of the Western Cape Department of Chemistry, the Virginia Tech Department of Crop and Soil Environmental Sciences, and the West Virginia

Water Research Institute National Mine Land Reclamation Center (WVWRI). The methods being compared are those developed at NETL, WVWRI, the EERC, and the 3-tier procedure published by Kosson and others (6). The EERC resu lts of this interlaboratory study were not yet available at the writing of this report but will be included in future project reports.

LEACHING RESULTS AND DISCUSSION

Sample descriptions for samples included in this study are shown in Appendix A. All leaching data are included in tabular form in Appe ndix B. As can be noted in Appendix B, not all leaching procedures were applied to all samp les. Where TCLP was included as one of the procedures applied, it was generally included b ecause of specific requests from the sample submitter. SGLP was generally applied to all su bmitted samples, and as noted in the report entitled “Laboratory Methods for the Evaluation of Potential Release of Mercury from Coal Utilization Byproducts,” SGLP applied using distil led deionized water is equivalent to ASTM

International D3987 Standard Test Method for Shake Extraction of Solid Waste with Water (7). For samples with a pH >10, the LTL procedure was also applied in order to assess the impact of reactivity of the material on the leaching profile of the sample.

Fly ash samples evaluated in this study for leachability of mercur y and other air toxic elements were from several sources and are delineated in the graphics in this report as noted in

Table 1.

Similarly, a variety of flue gas desulfurization (FGD) materi al samples were evaluated for leachability of mercury and other air toxic elements. Table 2 deta ils the types and descriptions

used for the FGD material s included in the study.4 Table 1. Fly Ash Sample Types and Descriptions Types of Fly Ash Sample Desc ription Used in Report Figures Currently generated fly ash from existing coal-fired system Fly ash – without mercury control

Fly ash collected from coal-fired system with mercury emission control installed (usually as a demonstration) Fly ash – with mercury control*

Fly ash collected at true baseline conditions in a system preparing to run a mercury emission control technology test Baseline fly ash (a subset of “Fly ash –

without mercury control”)

Fly ash collected during a mercury emission control technology test where a baseline fly ash sample was also collected Paired fly ash – with mercury control* (a subset of “Fly ash – with mercury control”)

* Note: “ with mercury control” indicates the presence of ac tivated carbon.

Table 2. FGD Material Types and Descriptions Types of FGD Materials Sample De scription Used in Report Figures Currently generated FGD material from existing coal-fired system FGD material – without mercury control

FGD material collected from system with mercury emission control installed (usually as a demonstration) FGD material – with mercury control

FGD material collecte d at true baseline conditions in a system preparing to run a mercury emission control technology test Baseline FGD material (a subset of “FGD

material – without mercury control”)

FGD material collected during a mercury emission control technology test where a

baseline FGD material was also collected Paired FGD material – with mercury control (a subset of “FGD material – with mercury control”)

In the text of this report, multiple figures ar e included for mercury and each of the air toxic elements of interest, as follows:

1. A figure comparing the total elemental con centration to all short- and long-term leachate concentrations generated in th e project for all samples of fly ash without and

with mercury control. Blue is used to represent concentrations of samples without mercury control and red represents samples with mercury control.

2. A figure showing the SGLP leaching results for the paired fly ash samples, where paired samples are represented with one color with open points for fly ash without mercury control and solid points for the paired fly ash with mercury control.

3. A figure showing all leachate results for a ll FGD materials evaluated including the only FGD material paired sample set, which are noted in each of these figures. Blue points represent results of samples without mercury control and a red point is used to5 represent the one sample generated with mercury control. In addition, samples of FGD gypsum collected at a single b ituminous-fired facility with selective cata lytic reduction (SCR) on and off are called out; however, th ese samples are not “paired” samples because they were collected several months apart.

Appendix C includes figures showing the short- and long-term leachi ng data for individual paired fly ash samples. The SGLP-only graphs were used in the text to allow ease of viewing the data, and the graphs of individu al paired fly ash sample sets provide more de tail and allow comparison of the short- and long-term leaching results.

Several samples had total elemental or leach ate concentrations below the lower limit of quantitation (LLQ). The LLQs were variable throughout the project, with some reported values below the LLQ of other samples. Therefore, th ese values are represented as one-half the LLQ graphically, and a red dashed lin e represents the highest LLQ.

Mercury Leaching Results

Mercury was the element of greatest interest for this project, and significant data were produced through Year 2 of the pr oject on the leaching profiles of mercury associated with fly ash. Additional figures are presented in the text for mercury leaching results. Figure 1 shows all short- and long-term leaching data for mercury for fly ash samples both without and with mercury control.

Figure 1. Total mercury vs. short- and long- term leachable mercury: all fly ash – without mercury control and fly ash – with mercury control samples. Th e x-axis is reduced from 120 μg/g.6 Figure 2 shows all short- and long-term mercury leaching data for baseline fly ash without mercury control and the paired fly ash with mercury control in addition to Figure 3, which shows only the SGLP mercury leaching data for this same sample set. In Figures 2 and 3, the baseline fly ash results are noted as open points and the paired fly ash with mercury control is noted as solid points. Paired samples are denoted by the same color points.

A comparison of short-term leaching results from SGLP and TCLP is shown in Figure 4. Results presented in Figure 4 show that neither of these short-term leaching tests resulted in a consistently higher or lower le achate concentration, indicating that neither test should be considered a more aggressive test.

Figure 5 summarizes all available mercury leach ing data for FGD materials. As noted, only a single sample with baseline FGD material and paired FGD material with mercury control is represented. In addition, sample s of FGD gypsum collected at a si ngle bituminous-f ired facility with SCR on and off are also called out in Figu re 5. Studies have shown that the speciation of mercury in the flue gas can be impacted by SCR systems, but as can be noted by the sample descriptions in Appendix A, these samples are not “paired” samples because they were collected several months apart. The variabil ity of mercury in coal over time has been noted in other studies and may be an explanation for the lower total me rcury in the sample with SCR on as compared to the one with SCR off. These samples are intere sting in that they point out the potential for erroneous conclusions if samples without mercury control are compar ed one-to-one with samples

Figure 2. Total mercury vs. short- and long-term l eachable mercury: all available paired fly ash samples. One paired sample set has two fly ash – with mercury control samples.7 Figure 3. Total mercury vs. SGLP leachable mercur y: all available paired fly ash samples. One paired sample set has two fly ash – with mercury control samples.

Figure 4. Total mercury vs. SGLP and TCLP leach able mercury: all available paired fly ash samples. One paired sample set has two fly ash – with mercury control samples.8 Figure 5. Total mercury vs. short- and long-term leachable mercury: all FGD material samples.

with mercury control, unless these samples are a true baseline sample and a paired sample with mercury control. Since many FGD materials exhib it a near-neutral pH, only a few FGD materials tested included LTL data points.

Based on the mercury leaching data currently available from this project, the following preliminary observations were made:

• Total mercury content of samples generated both with and without mercury emission controls present and leachate co ncentrations did not correlate.

• Leachate concentrations were independent of short-term leaching procedures used.

• Leachate mercury concentrations have been found to be extremely low regardless of the total mercury content of the sample. Most leachates exhibited mercury concentrations less than the reporting limit of 0.01 μg/L. All leachate concentrations fell well below the primary drinking water (PDW) limit of 2.0 μg/L for mercury as well as the limit at 30 × PDW (60 μg/L) and 100 × PDW (200 μg/L).

• Total mercury content of pa ired test fly ash samples with mercury control was consistently higher than the pa ired baseline fly ash sample without mercury control.9 Other Air Toxic Element Leaching Results

The other air toxic elements of interest for this project were arsenic, cadmium, chromium, lead, nickel, and selenium. SGLP and LTL only were evaluated for these elements because, as already noted, TCLP was only done on submitter request.

Arsenic

Figure 6 shows a comparison of the total arseni c concentrations versus the leachate arsenic concentrations for all fly ash samples without and with mercury control. The fly ash samples

without and with mercury control contained similar concen trations of total ar senic and generally leached similar levels of arsenic. Leaching results from baseline fly ash and paired fly ash with mercury control are shown in Figure 7. The presence of activated carbon in the samples designated as with mercury control does not correlate with a higher total arsenic concentration for this limited sample set. The FGD material data shown in Figure 8 may indicate that FGD materials with higher total arsenic concentrations may leach higher levels of arsenic; however, the sample set is too small to draw a firm co nclusion. Data on the paired sample set are very similar and within the error of the experiments and analytical procedures, so no conclusions can be drawn based on those data po ints. Figure C-3 show s that the long-term leachates exhibited lower arsenic concentrations than the SGLP, a nd this trend can also be seen in Figure C-4.

Figure 6. Total arsenic vs. short- and long- term leachable arsenic: all fly ash – without mercury control and fly ash – with mercury control samples.10 Figure 7. Total arsenic vs. SGLP leachable arse nic: all available paired fly ash samples.

Figure 8. Total arsenic vs. short- and long-term l eachable arsenic: all FGD material samples. One sample had a total arsenic LLQ higher than the reported value of another sample.11 Cadmium

Figures 9–11 are results of cadmium leaching, with Figure 9 including all samples of fly

ash without and with mercury control and Figure 10 comparing the baseline fly ash with the paired fly ash with mercury control. Figure 11 shows the data on the FGD materials evaluated. Results are similar to those noted for arsenic, with no indication that higher levels of cadmium are found in samples with activat ed carbon present and the limited data on the paired sample set varying within the limits of the test and analysis. As can be seen in Figure C-5, the three values reading above the LLQ for cadmium were from the SGLP. Remaining data points were at the LLQ.

Chromium

Figure 12, comparing all fly ash samples for total chromium versus leachate chromium, shows that there appears to be an increased ch romium leachate concentration for some fly ash samples with mercury control. Figure 13, showing the SGLP data for the paired fly ash sample sets, also indicates a small increase in chromium leachate concentrations for two sample sets. The third sample set has an unusually high LLQ a nd cannot be used to confirm or refute this observation. However, in Figure C-7, it can be noted that the long-term chromium leachate concentrations were significantly lower than those for the SGLP for two samples. The third sample did show a slightly higher total chro mium concentration for the paired fly ash with mercury control and subsequent slightly higher leachate concentrations for the long-term

Figure 9. Total cadmium vs. short- and l ong-term leachable cadmium: all fly ash – without mercury control and fly ash – with mercury control samples.12 Figure 10. Total cadmium vs. SGLP leachable cadmium: all availa ble paired fly ash samples.

Figure 11. Total cadmium vs. short- and long- term leachable cadmium: all FGD material samples.13 Figure 12. Total chromium vs. short- and l ong-term leachable chromium: all fly ash – without mercury control and fly ash – with mercury control samples. Several samples had a leachable chromium LLQ higher than the reported values of other samples.

Figure 13. Total chromium vs. SGLP leachable chro mium: all available paired fly ash samples. One paired sample set had a leachable chromium LLQ higher than the repo rted values of other samples.14 leaching tests. A reduced y-axis on Figure C-8 shows this in deta il; however, the SGLP values cannot be used in this evaluation because they are below the LLQ, as noted in the figure. Figure 14 shows the data on th e FGD materials evaluated.

Lead

As shown in Figures 15 through 17, leachate le ad concentrations were below the LLQ for most samples evaluated. It can be seen in Figure C-10 and C-11 that for one of the paired fly ash samples, the long-term leachate lead c oncentrations were well above the LLQ.

Nickel

Data for total nickel content versus leachat e nickel content in Figure 18 for all fly ash samples appears to indicate that thos e samples containing activated carbon ( with mercury control) exhibit reduced leaching of nickel, bu t the data in Figures 19 and C-13 through C-15 showing comparisons of the paired fly ash samp les are insufficient to support this observation. Figure 20 shows no correlation between total and leachable nickel for FGD materials.

Figure 14. Total chromium vs. short- and long- term leachable chromium: all FGD material samples.15 Figure 15. Total lead vs. short- and lo ng-term leachable lead: all fly ash – without mercury control and fly ash – with mercury control samples.

Figure 16. Total lead vs. SGLP leachable lead : all available paired fly ash samples.16 Figure 17. Total lead vs. short- and long-term leachable lead: all FGD material samples.

Figure 18. Total nickel vs. short- and long-term leachable nickel: all fly ash – without mercury control and fly ash – with mercury control samples. Several samples had a leachable nickel LLQ higher than the reported values of other sa mples. The x-axis is reduced from 300 μg/g.17 Figure 19. Total nickel vs. SGLP leachable nicke l: all available paired fly ash samples. One paired sample set had a leachable nickel LLQ hi gher than the reported values of other samples.

Figure 20. Total nickel vs. short- and long-term leachable nickel: all FGD material samples.18 Selenium

Figures 21 and 22 show the comparative conc entrations for total selenium and leachate selenium for fly ash samples w ith Figure 21 showing data point s for all fly ash samples and Figure 22 showing SGLP results for the paired fl y ash samples. Figure 23 contains data on the FGD materials evaluated including one paired sample. The seleni um data are under continuing review, but preliminary interpre tive efforts show similar total concentrations and leachate concentrations for fly ash regardless of the orig in of the sample. Repeat analyses of selected samples for total selenium and leaching will be performed.

Figure 21. Total selenium vs. short- and l ong-term leachable selenium: all fly ash – without mercury control and fly ash – with mercury control samples. Th e x-axis is reduced from 450 μg/g. The y-axis is reduced from 9000 μg/g.19 Figure 22. Total selenium vs. SGLP leachable sele nium: all available paired fly ash samples.

Figure 23. Total selenium vs. short- and long- term leachable selenium: all FGD material samples.20 SUMMARY

The data presented in this report include al l leaching data for the pr oject entitled “Mercury and Air Toxic Element Impacts of Coal Combus tion By-Product Disposal and Utilization.” The most complete data set is for the element mercury, and the data presented support the following preliminary conclusions:

• Total mercury content of samples generated both with and without mercury emission controls present and leachate co ncentrations did not correlate.

• Leachate concentrations were independent of short-term leaching procedures used.

• Leachate mercury concentrations have been found to be extremely low regardless of the total mercury content of the sample. Most leachates exhibited mercury concentrations less than the reporting limit of 0.01 μg/L. All leachate concentrations fell well below the PDW limit of 2.0 μg/L for mercury as well as the limit at 30 × PDW (60 μg/L) and 100 × PDW (200 μg/L).

• Total mercury content of pa ired test fly ash samples with mercury control was consistently higher than the pa ired baseline fly ash sample without mercury control.

For the remaining air toxic elements, the following preliminary observations can be made:

• The presence of activated carbon in fly ash samples with mercury control is not an

indicator of increased total c oncentrations of any of the air toxic elements studied. The data from a limited number of paired fly ash samples support this observation.

• Generally, higher total concentrations of air toxic elements do not correlate to higher

leachate concentrations.

• All air toxic elements showed reduced, increas ed, or variable leachate concentrations with increased time using the SGLP and LTL tests. Based on pr evious EERC work, these leaching profiles are expected to be sample-dependent.

Continuing work on leaching in this project will focus on adding leaching data from FGD materials and paired samples of both fly ash and FGD materials. Da ta verification will also be completed for inclusion in the project final repo rt. The results of an in terlaboratory comparison of leaching methods will also be completed by the c onclusion of this project, and results of that study will be reported in the project final report.

REFERENCES

1. Kim, A.G. CCB Leaching Summary: Survey of Methods and Results. In Proceedings of Coal Combustion By-Products and Western Coal Mines: A Technical Interactive Forum ; Golden, CO, April 16–18, 2002.21 2. Sorini, S.S. An Overview of Leaching Methods and Their Application to Coal Combustion By-Products. In Proceedings of the 12th Internati onal Symposium on the Management and Use of Coal Combustion Products (CCPs) ; Orlando, FL, Jan 26–30, 1997.

3. Kim, A.G. Results of CUB Leachi ng Studies: Metal Solubility. In Proceedings of the 15th International Symposium on the Management and Use of Coal Combustion Products (CCPs) ; St. Petersburg, FL, Jan 27–30, 2003.

4. Hassett, D.J. The Synthetic Groundwater Leaching Procedure. In Encyclopedia of Environmental Analysis and Remediation ; Meyers, R.A., Ed.; John Wiley and Sons: New York, 1998; pp 4797–4803.

5. USEPA Method 1311, Toxicity Characteristic Leaching Procedure, Test Methods for Evaluating Solid Waste, Physical/Chemical Methods, EPA Publication SW-846, Third Edition, as amended by Updates I, II, IIB, and III, finalized in the Federal Register on June 13, 1997.

6. Kosson, D.S.; van der Sloot, H.A.; Sanchez, F.; Garrabrants, A.C. An Integrated Framework for Evaluating Leaching in Waste Management and Utilization of Secondary Materials. Environmental Engineering Science 2002

, 19 (3), 159–203.

7. American Society for Testing and Materials. Standard Test Method for Shake Extraction of

Solid Waste with Water. In Annual Book of ASTM Standards ; Section 11: Water and

Environmental Techno logy, ASTM D3987-85, 2004.

## APPENDIX A

Hg/ATE PROJECT SAMPLE SET AND ANALYSIS

STATUSHg/ATE Project Sample Set and Analysis StatuspH = pH too low.IS = Insufficient sample.LP/SOW = Low priority, analysis was not part of the proposed statement of work.LP/ID = Low priority, insufficient sample identification information.NA = Not applicable.ID No. Sample Type Coal Type Hg Control Hg (μg/g) pH LOI Hg Total Total Trace SGLP 30-day LTL 60-day LTLThermalCurveLong-TermAmbient Microbiological Carbon Forms02-002 Fly ash Eastern bituminous Yes 30.6 3.62 24.2% Completed IS Completed pH pH Under way IS IS Completed02-003 Fly ash Eastern bituminous Yes 21.7 3.91 19.3% Completed LP Completed pH pH Under way IS IS LP/SOW02-004 Fly ash Subbituminous Yes 5.50 11.47 IS Completed IS Completed Completed Completed Under way IS IS Completed02-005 Fly ash Subbituminous Yes 4.73 10.65 IS Completed IS Completed Completed Completed Under way IS IS LP/SOW02-006 Fly ash Subbituminous Yes 5.81 10.86 3.88% Completed Completed Completed IS IS Under way IS IS LP/SOW02-007 Fly ash Eastern bituminous Yes 120 3.54 24.3% Completed LP Completed pH pH Under way IS IS Completed02-069 Fly ash Eastern bituminous Yes 0.526 8.94 12.6% Completed Completed Completed pH pH Under way IS IS LP/SOW02-070 Fly ash Eastern bituminous No 0.197 10.25 5.85% Completed Completed Completed Pending Pending Under way IS IS Completed02-071 Fly ash Eastern bituminous Yes 0.595 9.59 17.2% Completed Completed Completed pH pH Under way IS IS LP/SOW02-072 Fly ash Eastern bituminous No 0.158 10.35 5.18% Completed Completed Completed Pending Pending Under way IS IS LP/SOW02-073 Fly ash Eastern bituminous No 0.205 12.56 5.00% Completed Completed Completed Pending Pending Under way IS IS LP/SOW02-074 Fly ash Eastern bituminous No 0.526 12.18 6.09% Completed Completed Completed Pending Pending Under way IS IS LP/SOW02-076 Fly ash Eastern bituminous Yes 0.400 9.93 21.0% Completed LP Completed pH pH Under way IS IS Completed03-004 Fly ash Eastern bituminous No 0.0973 4.26 3.20% Completed Completed Completed pH Completed Under way NA – low Hg NA – low Hg Completed03-005 Fly ash Eastern bituminous No 0.0842 4.26 3.59% Completed Completed Completed pH Completed Under way NA – low Hg NA – low Hg Completed03-006 Fly ash Eastern bituminous No 0.194 4.60 5.28% Completed Completed Completed pH Completed Under way Completed Pending Completed03-007 Fly ash Eastern bituminous No 0.141 4.15 4.41% Completed Completed Completed pH Completed Under way Pending Pending Completed03-008 Fly ash Eastern bituminous No 0.119 11.72 IS Completed IS Completed IS IS Under way IS IS Completed03-009 Fly ash Eastern bituminous Yes 0.198 11.79 IS Completed IS Completed IS IS IS IS IS NA03-010 Fly ash Eastern bituminous Yes 0.371 10.34 IS Completed IS Completed IS IS IS IS IS NA03-011 Fly ash Unknown Yes 0.618 8.44 10.5% Completed LP Completed pH pH Under way IS IS LP/SOW03-012 Fly ash Unknown Yes 1.09 11.58 12.8% Completed IS Completed IS IS Under way IS IS LP/SOW03-013 Fly ash Unknown Yes 0.362 10.39 10.9% Completed LP Completed IS IS Under way IS IS LP/SOW03-014 Fly ash Unknown Yes 1.21 9.95 10.9% Completed LP Completed NA NA Under way NA NA LP/SOW03-015 Fly ash Unknown Yes IS 10.52 IS IS IS Completed NA NA NA NA NA NA03-016 Fly ash Lignite No 0.0161 12.60 0.34% Completed Completed Pending Pending Pending Under way Pending Pending Completed03-017 Fly ash Lignite Yes 0.225 12.57 0.96% Completed Completed LP/Composite LP/Composite LP/Composite Under way Completed Pending Completed03-018 Fly ash Lignite Yes 0.289 12.57 0.97% Completed Completed LP/Composite LP/Composite LP/Composite Under way Completed Pending Completed03-019 Fly ash Lignite Yes 2.22 11.74 4.21% Completed Completed LP/Composite LP/Composite LP/Composite Under way IS IS Completed03-060 Fly ash Subbituminous Yes 1.86 11.32 2.28% Completed Completed Completed Completed Completed Under way Completed Completed Completed03-061 Fly ash Subbituminous No 0.578 12.02 1.00% Completed Completed Completed Completed Completed Under way Completed Pending Completed03-062 Fly ash Lignite Yes 0.490 12.57 1.29% Completed Completed Completed Completed Completed Under way Completed Pending Completed03-063 Fly ash Eastern bituminous No < 0.005 11.30 0.47% Completed Completed Completed Completed Completed Under way Pending Pending Completed03-065 Gypsum Eastern bituminous No 0.0440 8.59 1.22% Completed Completed Completed pH Completed Under way Pending Pending NA03-067 FGD Slurry Eastern bituminous No < 0.1 8.05 6.38% Completed Completed Pending pH pH Pending Pending Pending NA03-074 Dust collector ash Lignite No < 0.005 12.63 34.5% Completed Completed Completed NA – low Hg Completed Under way NA – low Hg NA – low Hg Completed03-075 Fly ash Lignite No 1.40 12.70 15.4% Completed Completed Completed Completed Completed Under way IS IS Completed03-076 Fly ash Lignite No 0.553 12.71 21.5% Completed Completed Completed Completed Completed Under way IS Pending Completed03-077 Fly ash Lignite No 2.03 11.85 IS Completed Completed Completed Completed Completed Under way IS IS Completed03-078 Fly ash Lignite No 0.662 11.59 IS Completed IS Completed IS IS Under way IS IS Completed03-079 Fly ash Lignite No 0.785 11.72 2.54% Completed Completed Completed Completed Completed Under way IS Completed Completed03-080 Fly ash Lignite No 0.440 11.64 7.48% Completed Completed Completed Completed Completed Under way Pending Pending Completed03-081 Fly ash Lignite No 0.459 11.26 1.15% Completed Completed Completed Completed Completed Under way IS IS LP/SOW03-082 FGD filtercake Eastern bituminous No 0.218 7.47 4.20% Completed Completed Completed Completed Completed Pending Underway Completed NA03-083 Fly ash Eastern bituminous No 0.0174 4.28 1.20% Completed Completed Completed pH pH Under way Pending Pending Completed03-084 Fixated FGD Eastern bituminous No 0.180 12.52 3.17% Completed Completed Completed Completed Completed Under way Pending Pending LP/SOW03-085 Fly ash Eastern bituminous No 0.0337 7.06 2.10% Completed Completed Completed pH pH Under way Pending Pending LP/SOW03-086 FGD filtercake Eastern bituminous No 0.162 7.70 5.87% Completed Completed Pending pH pH Pending Pending Pending NA03-087 Fixated FGD Eastern bituminous No 0.136 12.51 3.80% Completed Completed Completed Completed Completed Pending Pending Pending LP/SOW03-088 Fly ash Eastern bituminous No 0.0103 7.50 1.07% Completed Completed Completed Completed Completed Under way Pending Pending LP/SOW03-089 Gypsum Eastern bituminous No 0.0960 8.22 1.94% Completed Completed Completed pH Completed Under way Pending Pending NA03-103 FGD slurry water Eastern bituminous No Pending 6.73 NA – water Underway Underway NA – water NA – water NA – water NA – water NA – water NA – water NA – water03-104 FGD Filtercake Water Eastern bituminous No Pending 6.53 NA – water Underway Underway NA – water NA – water NA – water NA – water NA –water NA – water NA – waterA-1Hg/ATE Project Sample Set and Analysis StatuspH = pH too low.IS = Insufficient sample.LP/SOW = Low priority, analysis was not part of the proposed statement of work.LP/ID = Low priority, insufficient sample identification information.NA = Not applicable.ID No. Sample Type Coal Type Hg Control Hg (μg/g) pH LOI Hg Total Total Trace SGLP 30-day LTL 60-day LTLThermalCurveLong-TermAmbient Microbiological Carbon Forms04-003 Fly ash Eastern bituminous No 0.685 9.34 8.44% Completed Completed Completed Completed Completed Under way Pending Pending LP/SOW04-004 Fly ash Eastern bituminous No 0.0411 10.29 1.38% Completed Completed Completed Completed Completed Under way Pending Pending LP/SOW04-006 Fly ash Western bituminous No 0.144 11.52 1.42% Completed Completed Completed Completed Completed Under way Underway Pending LP/SOW04-007 Fly ash Western bituminous No 0.521 13.00 2.46% Completed Completed Completed Completed Completed Under way Underway Pending LP/SOW04-029 Fly ash Subbituminous No 0.261 12.37 0.48% Completed Completed Completed Completed Completed Under way Pending Pending LP/SOW04-030 Fly ash Lignite Yes 0.147 11.51 0.70% Completed Completed Completed Completed Completed Under way IS Pending LP/SOW04-031 Fly ash Lignite Yes 0.174 11.60 0.64% Completed Completed Completed Completed Completed Under way IS IS LP/SOW04-032 Fly ash Lignite Yes 0.470 9.67 1.09% Completed Completed Completed pH pH Under way IS IS LP/SOW04-033 Fly ash Lignite Yes 1.43 10.70 1.27% Completed Completed Completed Completed Completed Under way IS IS LP/SOW04-034 Fly ash Unknown No 0.424 11.92 29.3% Completed Underway Completed Completed Completed LP/ID LP/ID LP/ID LP/SOW04-035 Fly ash Lignite No 0.159 12.68 2.24% Completed Completed Completed Completed Completed Completed Under way Pending LP/SOW04-036 Fly ash Lignite Yes 0.287 12.64 2.16% Completed Completed Completed Completed Completed Completed Under way Pending LP/SOW04-037 Fly ash Lignite/subbituminous No 0.435 11.80 Pending Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-038 Fly ash Lignite/subbituminous No 0.802 11.72 Pending Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-039 Fly ash Lignite/subbituminous No 0.767 11.32 Pending Completed Pending Pending Pending Pending Pending IS Pending LP/SOW04-040 Fly ash Lignite/subbituminous No 0.507 9.58 Pending Completed Pending Pending Pending Pending Pending IS Pending LP/SOW04-041 Fly ash Lignite/subbituminous No 0.287 IS IS Completed Pending IS IS IS IS IS IS IS04-042 Fly ash Lignite No 0.371 11.77 Pending Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-043 Fly ash Lignite No 0.689 11.48 Pending Completed Pending Pending Pending Pending Pending IS Completed LP/SOW04-044 Fly ash Lignite No 0.878 11.52 Pending Completed Pending Pending Pending Pending Pending IS Pending LP/SOW04-045 Fly ash Lignite No 0.849 IS IS Completed Pending Pending IS IS IS IS IS IS04-054 Fly ash Eastern bituminous Yes 17.7 6.40 18.6% Completed Completed Completed NA NA Completed Under way Pending LP/SOW04-055 Field – fly ash Lignite No 0.0070 Pending 5.73% Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-056Field – wet FGD/MillRejects Lignite No 0.187 Pending 3.31% Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-057Field – Wet FGD/millrejects Lignite No 0.207 Pending 2.18% Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-058 Field – soil Lignite No 0.0500 Pending 6.88% Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-059 Field – bottom ash Lignite No 0.0440 Pending 1.99% Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-060 Field – wet FGD Lignite No 0.299 Pending 2.49% Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-061 Field – bottom ash Lignite No < 0.005 Pending 13.0% Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-062 Field – bottom ash Lignite No < 0.005 Pending 7.73% Completed Pending Pending Pending Pending LP/SOW LP/SOW LP/SOW LP/SOW04-063 Field – FGD/fly ash Lignite No 0.0800 Pending 3.40% Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-064 Field – FGD/fly ash Lignite No 0.250 Pending 2.68% Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-065 Field – FGD/fly ash Lignite No 0.0110 Pending 3.68% Completed Pending Pending Pending Pending Pending Pending Pending LP/SOW04-067 Fly ash Subbituminous Yes 0.640 12.80 2.11% Completed Completed Underway Pending Pending Under way Under way Pending LP/SOW04-082 FGD gypsum Eastern bituminous No 0.0430 8.10 1.60% Completed Completed Underway pH pH Pending Pending Pending LP/SOW04-083 FGD gypsum Eastern bituminous No 0.103 8.10 2.26% Completed Completed Underway pH pH Pending Pending Pending LP/SOW05-001 Fly ash Lignite No < 0.005 12.84 0.90% Completed Completed Underway Pending Pending Under way Pending Pending LP/SOW05-002 FGD–SDA Lignite No < 0.005 12.85 0.95% Completed Completed Underway Pending Pending Under way Pending Pending LP/SOW05-003 Fly ash Lignite Yes 0.565 12.85 1.04% Completed Completed Underway Pending Pending Under way Pending Pending LP/SOW05-004 FGD–SDA Lignite Yes 0.332 13.06 1.12% Completed Completed Underway Pending Pending Under way Pending Pending LP/SOW05-005 Fly ash Lignite No 0.431 Pending Pending Completed Pending Underway Pending Pending Under way Pending Pending LP/SOW05-006 FGD slurry Lignite No Pending Pending Pending Pending Pending Pending Pending Pending Pending IS Pending LP/SOW05-007 FGD slurry water Lignite No Underway Pending NA Underway Underway NA – water NA – water NA – water NA – water NA – water NA – water NA– water99-188 Fly ash + FGD–SDA Subbituminous No 0.112 12.34 2.07% Completed Completed Completed Completed Completed Under way Completed Completed LP/SOWA-2

## APPENDIX B

TABLESB-1 Table B-1. Fly Ash Arsenic Data ID No. Hg Control As, μg/g SGLP 30-Day LTL 60-Day LTL TCLP

02-006 Yes 37.4 3.5 NT* NT NT

03-004 No 72.2 7.7 NT 118 NT

03-005 No 71.4 4.4 NT 6.5 NT

03-006 No 78 19.2 NT 110 NT

03-007 No 70.4 20 NT 10.6 NT

03-011 Yes NT NT NT NT 1482

03-060 Yes 19.4 2.7 <2 <2 NT

03-061 No 43.5 2 <2 <2 NT

03-062 Yes 43.3 6.6 <2 5.2 NT

03-063 No 45.5 67.8 37.7 36.1 NT

03-075 No 42.2 5.4 20.3 26 NT

03-076 No 25.6 3.3 5.2 12.2 NT

03-077 No 36.8 18.4 7.6 10.8 NT

03-078 No NT 95.1 NT NT NT

03-079 No 351 75.7 45.3 54.6 NT

03-080 No 157 44.6 35.2 29.0 NT

03-081 No 492 140 232 224 NT

03-083 No 166 97.3 NT NT NT

03-085 No 145 266 NT NT NT

03-088 No 44 18.4 23 23.4 NT

04-003 No 46 188 305 309 NT

04-004 No 31.5 136 135 140 NT

04-006 No 5.9 12.3 3.4 7.3 NT

04-007 No 7.09 10.7 <2 <2 NT

04-029 No 31.1 <2 <2 <2 NT

04-030 Yes 136 26.9 8.1 10.6 NT

04-031 Yes 134 23.2 9.6 11.5 NT

04-032 Yes 161 28 NT NT NT

04-033 Yes 148 31.1 10.1 10.4 NT

04-034 No NT 30.8 15.2 16.0 NT

04-035 No 36 <2 <2 <2 NT

04-036 Yes 44.9 <2 <2 <2 NT

04-054 Yes 444 842 NT NT NT

04-067 Yes 26.8 15.2 NT NT NT

05-001 No 24.4 3 NT NT NT

05-003 Yes 28.6 7.2 NT NT NT

05-005 No NT 134 NT NT NT

*=Not tested.B-2 Table B-2. Fly Ash Cadmium Data ID No. Hg Control Cd, μg/g SGLP 30-Day LTL 60-Day LTL TCLP

02-006 Yes 1.97 <0.2 NT NT NT

03-004 No <1 6.27 NT 1.11 NT

03-005 No <1 7.72 NT 7.22 NT

03-006 No 1.36 4.31 NT 1.37 NT

03-007 No <1 7.83 NT 6.7 NT

03-011 Yes NT NT NT NT 27.4

03-060 Yes 1.87 <0.2 <0.2 <0.2 NT

03-061 No 1.72 <0.2 <0.2 <0.2 NT

03-062 Yes <1 0.34 <0.2 <0.2 NT

03-063 No <1 <0.2 0.64 0.61 NT

03-075 No 1.47 <0.2 0.42 0.51 NT

03-076 No <1 <0.2 0.25 0.29 NT

03-077 No 2.82 0.35 0.21 <0.2 NT

03-078 No NT 0.43 NT NT NT

03-079 No 2.1 0.37 4.23 4.18 NT

03-080 No 1.06 1.57 1.97 2.10 NT

03-081 No 3.6 3.75 6.02 5.49 NT

03-083 No 3.57 <0.2 NT NT NT

03-085 No 2.55 0.28 NT NT NT

03-088 No 8.59 4.93 7.64 8.3 NT

04-003 No <1 0.56 0.88 0.74 NT

04-004 No <1 0.7 1.02 0.84 NT

04-006 No <1 0.28 0.36 0.33 NT

04-007 No <1 <0.2 <0.2 <0.2 NT

04-029 No 1.07 <0.2 <0.2 <0.2 NT

04-030 Yes 3.34 1.4 1.86 2.35 NT

04-031 Yes 3.24 1.49 1.95 2.34 NT

04-032 Yes 3.38 1.24 NT NT NT

04-033 Yes 2.91 1.32 1.99 2.46 NT

04-034 No NT 0.217 0.27 0.5 NT

04-035 No <1 <0.2 <0.2 <0.2 NT

04-036 Yes <1 0.27 <0.2 <0.2 NT

04-054 Yes 1.16 1.87 NT NT NT

04-067 Yes 0.942 0.39 NT NT NT

05-001 No 0.669 0.24 NT NT NT

05-003 Yes 0.755 0.3 NT NT NT

05-005 No NT 2.79 NT NT NTB-3 Table B-3. Fly Ash Chromium Data ID No. Hg Control Cr, μg/g SGLP 30-Day LTL 60-Day LTL TCLP

02-006 Yes 111 560 NT NT NT

03-004 No 142 <50 NT 10.1 NT

03-005 No 148 <2 NT <2 NT

03-006 No 135 <50 NT 7.5 NT

03-007 No 137 <50 NT <2 NT

03-011 Yes NT NT NT NT 437

03-060 Yes 76.7 <50 6.3 10.7 NT

03-061 No 67.6 <50 3 3.2 NT

03-062 Yes 54.4 80 3.6 5.2 NT

03-063 No 128 <50 38.6 38.8 NT

03-075 No 26.1 <2 <2 <2 NT

03-076 No 25.5 <2 <2 <2 NT

03-077 No 17.1 <50 16.1 <2 NT

03-078 No NT 150 NT NT NT

03-079 No 83.2 150 265 263 NT

03-080 No 66.1 90 134 122 NT

03-081 No 85.2 120 264 252 NT

03-083 No 137 <50 NT NT NT

03-085 No 124 <50 NT NT NT

03-088 No 160 110 160 180 NT

04-003 No 135 48.8 69.3 70.3 NT

04-004 No 144 70 98.1 100 NT

04-006 No 43.8 34.6 49.2 52.8 NT

04-007 No 64.9 120 7.3 6.7 NT

04-029 No 63.7 24.1 5.1 2.3 NT

04-030 Yes 92.8 399 640 670 NT

04-031 Yes 91.8 410 650 680 NT

04-032 Yes 94.8 333 NT NT NT

04-033 Yes 86.5 351 580 620 NT

04-034 No NT 29.5 62.5 83.3 NT

04-035 No 55.4 55.8 <2 2.1 NT

04-036 Yes 48.8 67.6 <2 2.1 NT

04-054 Yes 115 17.3 NT NT NT

04-067 Yes 44.8 <2 NT NT NT

05-001 No 45.1 45.3 NT NT NT

05-003 Yes 45.5 49.9 NT NT NT

05-005 No NT 137 NT NT NTB-4 Table B-4. Fly Ash Lead Data ID No. Hg Control Pb, μg/g SGLP 30-Day LTL 60-Day LTL TCLP

02-006 Yes 60.2 <2 NT NT NT

03-004 No 65.4 <2 NT <2 NT

03-005 No 72.6 <2 NT <2 NT

03-006 No 94.3 <2 NT <2 NT

03-007 No 80.7 <2 NT <2 NT

03-011 Yes NT NT NT NT 37.4

03-060 Yes 82.2 <2 3 2.4 NT

03-061 No 59.5 <2 3.6 8.5 NT

03-062 Yes 30.3 <2 <2 <2 NT

03-063 No 37.1 <2 <2 <2 NT

03-075 No 58.9 <2 2.9 2.1 NT

03-076 No 17 <2 <2 <2 NT

03-077 No 137 2.6 <2 <2 NT

03-078 No NT <2 NT NT NT

03-079 No 68.3 <2 <2 <2 NT

03-080 No 39.9 <2 <2 <2 NT

03-081 No 124 <2 <2 <2 NT

03-083 No 265 <2 NT NT NT

03-085 No 247 <2 NT NT NT

03-088 No 249 <2 <2 <2 NT

04-003 No 60.5 <2 <2 <2 NT

04-004 No 55.7 <2 <2 <2 NT

04-006 No 38.8 <2 <2 <2 NT

04-007 No 29.1 <2 2.2 <2 NT

04-029 No 38.6 <2 <2 <2 NT

04-030 Yes 85.3 <2 <2 <2 NT

04-031 Yes 83.4 <2 <2 <2 NT

04-032 Yes 74.9 <2 NT NT NT

04-033 Yes 74.9 <2 <2 <2 NT

04-034 No NT <1 <1 <1 NT

04-035 No 21.9 <2 <2 <2 NT

04-036 Yes 18.7 3 <2 <2 NT

04-054 Yes 49 <2 NT NT NT

04-067 Yes 25.9 2.2 NT NT NT

05-001 No 17.4 <2 NT NT NT

05-003 Yes 21.2 <2 NT NT NT

05-005 No NT <2 NT NT NTB-5 Table B-5. Fly Ash Mercury Data
ID No. Hg Control Hg, μg/g SGLP 30-Day LTL 60-Day LTL TCLP

02-002 Yes 30.6 <0.01 NT NT <0.01

02-003 Yes 21.7 <0.01 NT NT <0.01

02-004 Yes 5.5 <0.01 <0.01 <0.01 <0.01

02-005 Yes 4.73 <0.01 <0.01 0.01 <0.01

02-006 Yes 5.81 0.064 NT NT <0.01

02-007 Yes 120 <0.01 NT NT NT

02-069 Yes 0.526 0.03 NT NT 0.07

02-070 No 0.197 0.01 NT NT 0.03

02-071 Yes 0.595 0.01 NT NT <0.01

02-072 No 0.158 0.02 NT NT 0.02

02-073 No 0.205 0.05 NT NT 0.02

02-074 No 0.526 0.01 NT NT <0.01

02-076 Yes 0.4 0.016 NT NT <0.01

03-004 No <0.1 <0.01 NT 0.012 NT

03-005 No <0.1 0.01 NT 0.239 NT

03-006 No 0.194 <0.01 NT 0.06 NT

03-007 No 0.141 <0.01 NT <0.01 NT

03-008 No 0.119 <0.01 NT NT 0.034

03-009 Yes 0.198 <0.01 NT NT <0.01

03-010 Yes 0.371 <0.01 NT NT <0.01

03-011 Yes 0.618 <0.01 NT NT 0.17

03-012 Yes 1.09 <0.01 NT NT <0.01

03-013 Yes 0.362 <0.01 NT NT <0.01

03-014 Yes 1.21 0.018 NT NT 0.01

03-015 Yes NT <0.01 NT NT <0.01

03-060 Yes 1.86 <0.01 <0.01 0.037 NT

03-061 No 0.578 <0.01 <0.01 0.325 NT

03-062 Yes 0.490 <0.01 <0.01 <0.01 NT

03-063 No <0.1 <0.01 <0.01 0.038 NT

03-075 No 1.40 0.039 <0.01 0.13 NT

03-076 No 0.553 0.087 <0.01 0.027 NT

03-077 No 2.03 <0.01 <0.01 0.054 NT

03-078 No 0.662 <0.01 NT NT NT

03-079 No 0.785 <0.01 <0.01 0.02 NT

03-080 No 0.440 0.011 0.113 0.023 NT

03-081 No 0.469 0.083 0.013 0.018 NT

03-083 No <0.1 <0.01 NT NT NT

03-085 No <0.1 <0.01 NT NT NT

03-088 No <0.1 0.029 <0.01 <0.01 NT

04-003 No 0.685 <0.01 0.04 <0.01 NT

04-004 No <0.1 <0.01 <0.01 0.077 NT

04-006 No 0.144 <0.01 0.076 0.087 NT

04-007 No 0.521 0.021 0.035 <0.01 NT

04-029 No 0.261 0.023 <0.01 <0.01 NT

04-030 Yes 0.147 <0.01 <0.01 <0.01 NT

04-031 Yes 0.174 0.012 <0.01 0.028 NT

04-032 Yes 0.470 <0.01 NT NT NT

04-033 Yes 1.43 <0.01 <0.01 <0.01 NT

04-034 No 0.424 <0.2 <0.2 <0.2 NT

04-035 No 0.159 0.081 0.02 <0.01 NT

04-036 Yes 0.287 0.016 <0.01 <0.01 NT

04-054 Yes 17.7 <0.01 NT NT NT

04-067 Yes 0.640 <0.01 NT NT NT

05-001 No <0.1 <0.01 NT NT NT

05-003 Yes 0.565 <0.01 NT NT NT

05-005 No 0.431 <0.01 NT NT NTB-6 Table B-6. Fly Ash Nickel Data

ID No. Hg Control Ni, μg/g SGLP 30-Day LTL 60-Day LTL TCLP

02-006 Yes 50.6 <2 NT NT NT

03-004 No 68.3 50 NT 8.1 NT

03-005 No 85.7 63.2 NT 70 NT

03-006 No 60.4 40 NT 18.2 NT

03-007 No 71.3 50 NT 70 NT

03-011 Yes NT NT NT NT 279

03-060 Yes 67.6 <40 4.5 <2 NT

03-061 No 93.9 <40 4.1 <2 NT

03-062 Yes 57.6 <40 <2 <2 NT

03-063 No 23.3 <40 <2 <2 NT

03-075 No 25.4 <2 <2 <2 NT

03-076 No 24.6 <2 <2 <2 NT

03-077 No 17.8 <40 <2 <2 NT

03-078 No NT <40 NT NT NT

03-079 No 40.9 <40 <2 <2 NT

03-080 No 63.5 <2 <2 <2 NT

03-081 No 68.4 <2 <2 <2 NT

03-083 No 259 <40 NT NT NT

03-085 No 277 <40 NT NT NT

03-088 No 74.5 <2 5.4 5.6 NT

04-003 No 76.6 <2 <2 <2 NT

04-004 No 81.6 <2 <2 <2 NT

04-006 No 26.1 <2 <2 <2 NT

04-007 No 22 <2 10.6 10 NT

04-029 No 39.9 <2 4 4.8 NT

04-030 Yes 24.2 <2 5.6 3.3 NT

04-031 Yes 28.2 <2 4.4 2.9 NT

04-032 Yes 40 <2 NT NT NT

04-033 Yes 29.1 <2 5.8 4.7 NT

04-034 No NT 5.97 4.07 <2 NT

04-035 No 17.2 <2 9.6 6.2 NT

04-036 Yes 23.5 <2 8.2 5.4 NT

04-054 Yes 94.5 5.6 NT NT NT

04-067 Yes 41.5 21 NT NT NT

05-001 No 30.3 43.6 NT NT NT

05-003 Yes 25.7 25.2 NT NT NT

05-005 No NT 15.5 NT NT NTB-7 Table B-7. Fly Ash Selenium Data ID No. Hg Control Se, μg/g SGLP 30-Day LTL 60-Day LTL TCLP

02-006 Yes 36.6 57.1 NT NT NT

03-004 No <1 16.7 NT 125 NT

03-005 No <1 14.7 NT 48.9 NT

03-006 No 5.27 48.5 NT 212 NT

03-007 No 0.792 36.6 NT 86.9 NT

03-011 Yes NT NT NT NT 165

03-060 Yes <1 8.4 8.5 11.4 NT

03-061 No 23.4 5.4 9.8 13.9 NT

03-062 Yes <1 68 <2 3.8 NT

03-063 No <1 29.1 42.6 37.4 NT

03-075 No <1 40.3 41.9 41.6 NT

03-076 No <1 19.1 16.6 13.8 NT

03-077 No 3.74 71.6 71.3 69.3 NT

03-078 No NT 151 NT NT NT

03-079 No <1 60.4 40.1 38.3 NT

03-080 No <1 75.1 23.8 23.4 NT

03-081 No <1 240 112 94.9 NT

03-083 No <1 44.1 NT NT NT

03-085 No <1 77.6 NT NT NT

03-088 No <1 76.4 15.5 19 NT

04-003 No 3.39 412 489 503 NT

04-004 No <1 166 186 180 NT

04-006 No <1 160 111 76.2 NT

04-007 No <1 265 26.7 17.4 NT

04-029 No <1 2.1 <2 <2 NT

04-030 Yes <1 222 53.2 63.4 NT

04-031 Yes <1 177 54.4 60.3 NT

04-032 Yes 5.41 215 NT NT NT

04-033 Yes 5.67 156 64.8 71 NT

04-034 No NT 113 12.8 21.1 NT

04-035 No <1 17.8 <2 <2 NT

04-036 Yes <1 19.9 <2 <2 NT

04-054 Yes 428 8620 NT NT NT

04-067 Yes 7.59 47.2 NT NT NT

05-001 No 3.38 12.9 NT NT NT

05-003 Yes 5.08 34.2 NT NT NT

05-005 No NT 123 NT NT NTB-8 Table B-8. FGD Material Arsenic Data ID No. Hg Control As, ug/g SGLP 30-Day LTL 60-Day LTL

99-188 No 14.7 3.5 2.6 2.2

03-065 No <1 <2 NT <2

03-082 No <1 3.7 3.5 <2

03-084 No 53.4 4.9 5.2 <2

03-087 No 53.8 7 24 19.1

03-089 No <1 <2 NT <2

04-082 No 1.65 <2 NT NT

04-083 No <2 <2 NT NT

05-002 No 22.6 2.1 NT NT

05-004 Yes 21.8 4.3 NT NT

Table B-9. FGD Material Cadmium Data ID No. Hg Control Cd, ug/g SGLP 30-Day LTL 60-Day LTL

99-188 No <1 0.37 0.58 0.59

03-065 No <1 <0.2 NT <0.2

03-082 No <1 <0.2 0.83 0.47

03-084 No 1.24 0.44 0.66 0.49

03-087 No 1.08 0.43 0.3 0.37

03-089 No 1.89 0.46 NT <0.2

04-082 No <0.5 0.33 NT NT

04-083 No <0.5 0.25 NT NT

05-002 No 0.703 0.22 NT NT

05-004 Yes 0.629 0.2 NT NT

Table B-10. FGD Material Chromium Data

ID No. Hg Control Cr, ug/g SGLP 30-Day LTL 60-Day LTL

99-188 No 26.3 111 215 223

03-065 No 2.9 <2 NT <2

03-082 No 10.4 <2 <2 <2

03-084 No 53.6 4.7 3.1 2.45

03-087 No 51.6 3 2.2 3.3

03-089 No 4.13 <2 NT <2

04-082 No 3.39 <2 NT NT

04-083 No 3.95 <2 NT NT

05-002 No 42.8 34.6 NT NT

05-004 Yes 37.3 21.8 NT NTB-9 Table B-11. FGD Material Lead Data ID No. Hg Control Pb, μg/g SGLP 30-Day LTL 60-Day LTL

99-188 No 37 <2 <2 <2

03-065 No <1 <2 NT <2

03-082 No 2.22 <2 <2 <2

03-084 No 80.3 14.3 <2 <2

03-087 No 86.7 6.6 <2 <2

03-089 No 2.08 <2 NT <2

04-082 No <2.5 <2 NT NT

04-083 No <2.5 <2 NT NT

05-002 No 18.6 <2 NT NT

05-004 Yes 20.9 <2 NT NT

Table B-12. FGD Material Mercury Data ID No. Hg Control Hg, μg/g SGLP 30-Day LTL 60-Day LTL

99-188 No 0.112 <0.01 <0.01 0.0428

03-065 No <0.1 <0.01 NT <0.01

03-082 No 0.218 0.404 <0.01 <0.01

03-084 No 0.18 0.289 <0.01 <0.01

03-087 No 0.136 0.237 <0.01 <0.01

03-089 No <0.1 <0.01 NT <0.01

04-082 No <0.1 <0.01 NT NT

04-083 No 0.103 <0.01 NT NT

05-002 No <0.1 <0.01 NT NT

05-004 Yes 0.332 <0.01 NT NT

Table B-13. FGD Mate rial Nickel Data ID No. Hg Control Ni, μg/g SGLP 30-Day LTL 60-Day LTL

99-188 No 12.9 21.7 <2 <2

03-065 No <1 <2 NT 10.1

03-082 No 3.5 7.4 32.1 25.4

03-084 No 87.2 <2 4 3.6

03-087 No 98.7 <2 <2 2.1

03-089 No <1 <2 NT 12.6

04-082 No 6.83 28.4 NT NT

04-083 No 6.81 23.3 NT NT

05-002 No 29.7 39.1 NT NT

05-004 Yes 25.3 29.3 NT NTB-10 Table B-14. FGD Material Selenium Data ID No. Hg Control Se, μg/g SGLP 30-Day LTL 60-Day LTL

99-188 No <1 47.9 53.5 53.1

03-065 No <1 3.3 NT 2.7

03-082 No <1 71.2 55.2 45.3

03-084 No <1 2.7 2.4 1.5

03-087 No <1 2.1 3.4 <2

03-089 No <1 9.4 NT 8.2

04-082 No <2.5 12.5 NT NT

04-083 No <2.5 18.7 NT NT

05-002 No 4.13 11.3 NT NT

05-004 Yes 3.71 24.3 NT NT

## APPENDIX C

FIGURESC-1 Figure C-1. Total mercury vs. short- and long-term leachable mercury: paired fly ash sample set ID

Nos. 03-060 and 03-061.

Figure C-2. Total mercury vs. short- and long-term leachable mercury: paired fly ash sample set ID

Nos. 04-035 and 04-036.C-2 Figure C-3. Total arsenic vs. short- and long-term leachable arsenic: all available paired fly ash samples.

Figure C-4. Total arsenic vs. short- and long-term leachable arsenic: paired fly ash sample set

ID Nos. 03-060 and 03-061.C-3 Figure C-5. Total cadmium vs. short- and long-term leachable cadmium: all available paired fly ash samples.

Figure C-6. Total cadmium vs. short- and long-term leachable cadmium: paired fly ash sample set

ID Nos. 03-060 and 03-061.C-4 Figure C-7. Total chromium vs. shor t- and long-term leachable chromi um: all available paired fly ash samples. One paired sample set had a leachable chromium LLQ higher than the reported values of other samples.

Figure C-8. Total chromium vs. short- and long-term leachable chromium: paired fly ash sample set ID Nos. 03-060 and 03-061. The SGLP leachable chromium LLQ was higher than the reported values of the long-term leachates.C-5 Figure C-9. Total chromium vs. shor t- and long-term leachable chromium: paired fly ash sample set

ID Nos. 04-035 and 04-036.

Figure C-10. Total lead vs. short- and long-term leach able lead: all available paired fly ash samples.C-6 Figure C-11. Total lead vs. short- and long-term leachable lead: paired fly ash sample set

ID Nos. 03-060 and 03-061.

Figure C-12. Total lead vs. short- and long-term leachable lead: paired fly ash sample set

ID Nos. 04-035 and 04-036.C-7 Figure C-13. Total nickel vs. short- and long-term leachable nickel: all av ailable paired fly ash samples. One paired sample set had a leach able nickel LLQ higher than the reported values of other samples.

Figure C-14. Total nickel vs. short- and long-term l eachable nickel: paired fly ash sample set ID Nos.

03-060 and 03-061. The SGLP leachable nick el LLQ was higher than the reported values of the long-term leachates.C-8 Figure C-15. Total nickel vs. short- and long-term leachable nickel: paired fly ash sample set

ID Nos. 04-035 and 04-036.

Figure C-16. Total selenium vs. short- and long-term leachable selenium: all available paired fly ash samples.C-9 Figure C-17. Total selenium vs. short- and long-term leachable selenium: paired fly ash sample set

ID Nos. 03-060 and 03-061.

Figure C-18. Total selenium vs. short- and long-term leachable selenium: paired fly ash sample set

ID Nos. 04-035 and 04-036

# APPENDIX O

SUMMARY OF LONG-TERM AMBIENTTEMPERATURE RELEASE DATAID No. Replicate BatchTestingPeriodNo. Daysin TestingPeriodTotal Hgon CCB(μg/g)% Hg on CCBReleased OverTesting PeriodYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Testing PeriodExperimentDuration,DaysCumulative % Hg on CCBSorption or Release overExperimentYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Experiment99-188 1 1 1 8 0.112 0% NA No sorption or release99-188 1 1 2 91 0.112 0% NA No sorption or release99-188 1 1 3 95 0.112 0.0000026% 9,864,357 Release 194 0.0000026% 20,144,056 Release99-188 2 1 1 8 0.112 -0.0000281% -77,875 Sorption99-188 2 1 2 91 0.112 -0.000300% -83,232 Sorption99-188 2 1 3 95 0.112 -0.000329% -79,095 Sorption 194 -0.000657% -80,930 Sorption99-456 1 1 1 8 1.39 -0.0000010% -2,189,765 Sorption99-456 1 1 2 91 1.39 -0.0000106% -2,361,255 Sorption99-456 1 1 3 95 1.39 -0.0000118% -2,212,209 Sorption 194 -0.0000233% -2,278,715 Sorption99-456 2 1 1 8 1.39 -0.0000005% -4,568,890 Sorption99-456 2 1 2 91 1.39 -0.0000049% -5,046,768 Sorption99-456 2 1 3 95 1.39 -0.0000055% -4,751,898 Sorption 194 -0.0000109% -4,877,518 Sorption00-048 1 1 1 8 0.361 -0.0000031% -717,111 Sorption00-048 1 1 2 91 0.361 -0.0000293% -850,697 Sorption00-048 1 1 3 95 0.361 -0.0000350% -743,129 Sorption 194 -0.0000674% -788,731 Sorption00-048 2 1 1 8 0.361 0% NA No sorption or release00-048 2 1 2 91 0.361 0% NA No sorption or release00-048 2 1 3 95 0.361 0.0000018% 14,313,423 Release 194 0.0000018% 29,229,517 Release01-002 1 1 1 8 0.187 -0.0000026% -853,552 Sorption01-002 1 1 2 91 0.187 -0.0000613% -406,857 Sorption01-002 1 1 3 95 0.187 -0.0000887% -293,589 Sorption 194 -0.000152% -348,532 Sorption01-002 2 1 1 8 0.187 -0.0000069% -319,622 Sorption01-002 2 1 2 91 0.187 -0.0000742% -335,780 Sorption01-002 2 1 3 95 0.187 -0.0000762% -341,639 Sorption 194 -0.000157% -337,914 Sorption01-008 1 1 1 8 1.22 0% NA No sorption or release01-008 1 1 2 91 1.22 0.0000020% 12,496,097 Release01-008 1 1 3 95 1.22 0.0000017% 15,517,310 Release 194 0.0000037% 14,472,785 Release01-008 2 1 1 8 1.22 0% NA No sorption or release01-008 2 1 2 91 1.22 0% NA No sorption or release01-008 2 1 3 95 1.22 0% NA No sorption or release 194 0% NA No sorption or release01-011 1 1 1 8 2.55 0% NA No sorption or release01-011 1 1 2 91 2.55 0.0000005% 53,747,404 Release01-011 1 1 3 95 2.55 0.0000002% 146,657,695 Release 194 0.0000006% 82,875,125 Release01-011 2 1 1 8 2.55 0% NA No sorption or release01-011 2 1 2 91 2.55 0.0000005% 47,851,501 Release01-011 2 1 3 95 2.55 0.0000003% 100,452,715 Release 194 0.0000008% 68,131,501 Release03-006 1 1 1 8 0.194 -0.0000047% -468,182 Sorption03-006 1 1 2 91 0.194 -0.0000533% -468,182 Sorption03-006 1 1 3 95 0.194 -0.0000520% -500,495 Sorption 194 -0.000110% -483,467 Sorption03-006 2 1 1 8 0.194 -0.0000038% -572,612 Sorption03-006 2 1 2 91 0.194 -0.0000382% -652,696 Sorption03-006 2 1 3 95 0.194 -0.0000425% -612,832 Sorption 194 -0.0000845% -629,031 Sorption03-017 1 1 1 8 0.225 0% NA No sorption or releasePage 1 of 9ID No. Replicate BatchTestingPeriodNo. Daysin TestingPeriodTotal Hgon CCB(μg/g)% Hg on CCBReleased OverTesting PeriodYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Testing PeriodExperimentDuration,DaysCumulative % Hg on CCBSorption or Release overExperimentYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Experiment03-017 1 1 2 91 0.225 0.0000029% 8,554,255 Release03-017 1 1 3 95 0.225 0.0000016% 16,430,687 Release 194 0.0000045% 11,814,972 Release03-017 2 1 1 8 0.225 -0.0000041% -532,956 Sorption03-017 2 1 2 91 0.225 -0.0000447% -557,211 Sorption03-017 2 1 3 95 0.225 -0.0000477% -545,382 Sorption 194 -0.0000966% -550,333 Sorption03-018 1 1 1 8 0.289 0% NA No sorption or release03-018 1 1 2 91 0.289 0.0000032% 7,890,762 Release03-018 1 1 3 95 0.289 0.0000018% 14,840,697 Release 194 0.0000049% 10,817,569 Release03-018 2 1 1 8 0.289 -0.0000051% -427,244 Sorption03-018 2 1 2 91 0.289 -0.0000565% -440,887 Sorption03-018 2 1 3 95 0.289 -0.0000602% -432,098 Sorption 194 -0.000122% -435,970 Sorption03-060 1 1 1 8 1.86 0% NA No sorption or release03-060 1 1 2 91 1.86 0.0000006% 44,570,210 Release03-060 1 1 3 95 1.86 0.0000002% 170,208,032 Release 194 0.0000007% 74,619,320 Release03-060 2 1 1 8 1.86 0% NA No sorption or release03-060 2 1 2 91 1.86 0.0000012% 20,994,849 Release03-060 2 1 3 95 1.86 0.0000009% 29,253,023 Release 194 0.0000021% 25,587,175 Release03-061 1 1 1 8 0.578 0.0000040% 550,923 Release03-061 1 1 2 91 0.578 0.0000023% 10,729,242 Release03-061 1 1 3 95 0.578 0.0000013% 19,586,941 Release 194 0.0000076% 6,965,200 Release03-061 2 1 1 8 0.578 -0.0000000428% -51,176,729 Sorption03-061 2 1 2 91 0.578 -0.0000165% -1,506,482 Sorption03-061 2 1 3 95 0.578 -0.0000164% -1,590,529 Sorption 194 -0.0000330% -1,612,762 Sorption03-062 1 1 1 8 0.490 0% NA No sorption or release03-062 1 1 2 91 0.490 0.0000026% 9,609,441 Release03-062 1 1 3 95 0.490 0.0000005% 52,785,429 Release 194 0.0000031% 17,214,465 Release03-062 2 1 1 8 0.490 0% NA No sorption or release03-062 2 1 2 91 0.490 0% NA No sorption or release03-062 2 1 3 95 0.490 0.0000004% 58,592,405 Release 194 0.0000004% 119,651,861 Release03-065 1 3 1 7 0.044 0.000137% 13,985 Release03-065 1 3 2 90 0.044 0.00209% 11,794 Release03-065 1 3 3 90 0.044 0.00229% 10,788 Release03-065 1 3 4 44 0.044 0.00185% 6,509 Release03-065 1 3 5 46 0.044 0.000751% 16,778 Release03-065 1 3 6 48 0.044 0.000318% 41,353 Release03-065 1 3 7 43 0.044 0.000420% 28,059 Release03-065 1 3 8 58 0.044 -0.000149% -106,573 Sorption03-065 1 3 9 47 0.044 -0.000142% -90,856 Sorption 473 0.00756% 17,133 Release03-065 2 3 1 7 0.044 0.000189% 10,142 Release03-065 2 3 2 90 0.044 0.000875% 28,181 Release03-065 2 3 3 90 0.044 0.00388% 6,350 Release03-065 2 3 4 44 0.044 0.00421% 2,863 Release03-065 2 3 5 46 0.044 0.00108% 11,624 ReleasePage 2 of 9ID No. Replicate BatchTestingPeriodNo. Daysin TestingPeriodTotal Hgon CCB(μg/g)% Hg on CCBReleased OverTesting PeriodYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Testing PeriodExperimentDuration,DaysCumulative % Hg on CCBSorption or Release overExperimentYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Experiment03-065 2 3 6 48 0.044 0.000229% 57,433 Release03-065 2 3 7 43 0.044 0.000310% 37,981 Release03-065 2 3 8 58 0.044 0.000341% 46,556 Release03-065 2 3 9 47 0.044 -0.0000260% -494,826 Sorption 473 0.0111% 11,678 Release03-082 1 2 1 7 0.248 0.000773% 2,480 Release03-082 1 2 2 44 0.248 0.0324% 372 Release03-082 1 2 3 46 0.248 0.0251% 501 Release03-082 1 2 4 46 0.248 0.0428% 294 Release03-082 1 2 5 45 0.248 0.0660% 187 Release03-082 1 2 6 58 0.248 0.0577% 275 Release03-082 1 2 7 33 0.248 0.0218% 415 Release03-082 1 2 8 45 0.248 0.0286% 431 Release03-082 1 2 9 47 0.248 0.0272% 473 Release03-082 1 2 10 43 0.248 0.0291% 405 Release03-082 1 2 11 44 0.248 0.0322% 375 Release03-082 1 2 12 46 0.248 0.0435% 290 Release03-082 1 2 13 45 0.248 0.0454% 272 Release03-082 1 2 14 45 0.248 0.0368% 335 Release03-082 1 2 15 59 0.248 0.0673% 240 Release03-082 1 2 16 46 0.248 0.0519% 243 Release 699 0.609% 315 Release03-082 2 2 1 7 0.248 0.0000172% 111,680 Release03-082 2 2 2 44 0.248 0.00525% 2,297 Release03-082 2 2 3 46 0.248 0.00596% 2,115 Release03-082 2 2 4 46 0.248 0.0133% 948 Release03-082 2 2 5 45 0.248 0.0323% 381 Release03-082 2 2 6 58 0.248 0.0388% 409 Release03-082 2 2 7 33 0.248 0.0111% 818 Release03-082 2 2 8 45 0.248 0.0175% 705 Release03-082 2 2 9 47 0.248 0.0186% 694 Release03-082 2 2 10 43 0.248 0.0205% 576 Release03-082 2 2 11 44 0.248 0.0199% 605 Release03-082 2 2 12 46 0.248 0.0284% 443 Release03-082 2 2 13 45 0.248 0.0367% 336 Release03-082 2 2 14 45 0.248 0.0285% 432 Release03-082 2 2 15 59 0.248 0.0496% 326 Release03-082 2 2 16 46 0.248 0.121% 104 Release 699 0.448% 428 Release03-082 3 3 1 7 0.248 0.0000234% 81,978 Release03-082 3 3 2 45 0.248 0.0170% 725 Release03-082 3 3 3 45 0.248 0.0380% 324 Release03-082 3 3 4 47 0.248 0.0489% 263 Release03-082 3 3 5 43 0.248 0.0562% 209 Release03-082 3 3 6 44 0.248 0.0511% 236 Release03-082 3 3 7 46 0.248 0.0766% 165 ReleasePage 3 of 9ID No. Replicate BatchTestingPeriodNo. Daysin TestingPeriodTotal Hgon CCB(μg/g)% Hg on CCBReleased OverTesting PeriodYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Testing PeriodExperimentDuration,DaysCumulative % Hg on CCBSorption or Release overExperimentYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Experiment03-082 3 3 8 45 0.248 0.0815% 151 Release03-082 3 3 9 45 0.248 0.0643% 192 Release03-082 3 3 10 59 0.248 0.375% 43.1 Release03-082 3 3 11 46 0.248 0.264% 47.7 Release 472 1.07% 120 Release03-082 4 3 1 7 0.248 0.000759% 2,527 Release03-082 4 3 2 45 0.248 0.0426% 289 Release03-082 4 3 3 45 0.248 0.0436% 283 Release03-082 4 3 4 47 0.248 0.0436% 295 Release03-082 4 3 5 43 0.248 0.0481% 245 Release03-082 4 3 6 44 0.248 0.0493% 245 Release03-082 4 3 7 46 0.248 0.0661% 191 Release03-082 4 3 8 45 0.248 0.0798% 154 Release03-082 4 3 9 45 0.248 0.0643% 192 Release03-082 4 3 10 59 0.248 0.227% 71.2 Release03-082 4 3 11 46 0.248 0.202% 62.4 Release 472 0.867% 149 Release03-082 5 3 1 7 0.248 0.000666% 2,878 Release03-082 5 3 2 45 0.248 0.0751% 164 Release03-082 5 3 3 45 0.248 0.0485% 254 Release03-082 5 3 4 47 0.248 0.0492% 262 Release03-082 5 3 5 43 0.248 0.0675% 175 Release03-082 5 3 6 44 0.248 0.0654% 184 Release03-082 5 3 7 46 0.248 0.103% 122 Release03-082 5 3 8 45 0.248 0.138% 89.5 Release03-082 5 3 9 45 0.248 0.0947% 130 Release03-082 5 3 10 63 0.248 0.217% 79.4 Release03-082 5 3 11 46 0.248 0.00652% 1,932 Release 476 0.866% 151 Release03-082 6 3 1 7 0.248 0.0000897% 21,385 Release03-082 6 3 2 45 0.248 0.0685% 180 Release03-082 6 3 3 45 0.248 0.0618% 200 Release03-082 6 3 4 47 0.248 0.0397% 324 Release03-082 6 3 5 43 0.248 0.0625% 188 Release03-082 6 3 6 44 0.248 0.0621% 194 Release03-082 6 3 7 46 0.248 0.109% 115 Release03-082 6 3 8 45 0.248 0.131% 94.0 Release03-082 6 3 9 45 0.248 0.116% 106 Release03-082 6 3 10 63 0.248 0.310% 55.7 Release03-082 6 3 11 46 0.248 0.00210% 5,989 Release 476 0.963% 135 Release04-006 1 2 1 7 0.144 -0.0000048% -396,725 Sorption04-006 1 2 2 90 0.144 -0.0000622% -396,725 Sorption04-006 1 2 3 91 0.144 -0.0000587% -424,930 Sorption 188 -0.000126% -409,894 Sorption04-006 2 2 1 7 0.144 -0.0000089% -214,953 Sorption04-006 2 2 2 90 0.144 -0.000113% -219,087 Sorption04-006 2 2 3 91 0.144 -0.000114% -218,809 Sorption 188 -0.000235% -218,795 SorptionPage 4 of 9ID No. Replicate BatchTestingPeriodNo. Daysin TestingPeriodTotal Hgon CCB(μg/g)% Hg on CCBReleased OverTesting PeriodYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Testing PeriodExperimentDuration,DaysCumulative % Hg on CCBSorption or Release overExperimentYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Experiment04-007 1 2 1 7 0.521 -0.0000020% -958,159 Sorption04-007 1 2 2 90 0.521 -0.0000329% -749,092 Sorption04-007 1 2 3 91 0.521 -0.0000336% -742,965 Sorption 188 -0.0000685% -752,201 Sorption04-007 2 2 1 7 0.521 -0.0000007% -2,748,990 Sorption04-007 2 2 2 90 0.521 -0.0000080% -3,093,527 Sorption04-007 2 2 3 91 0.521 -0.0000081% -3,079,637 Sorption 188 -0.0000168% -3,072,481 Sorption04-029 1 3 1 7 0.261 -0.0000006% -3,115,851 Sorption04-029 1 3 2 90 0.261 -0.0000160% -1,542,848 Sorption04-029 1 3 3 90 0.261 -0.0000138% -1,782,759 Sorption 187 -0.0000304% -1,683,717 Sorption04-029 2 3 1 7 0.261 0.0000001% 33,539,583 Release04-029 2 3 2 90 0.261 -0.0000178% -1,382,399 Sorption04-029 2 3 3 90 0.261 -0.0000155% -1,590,153 Sorption 187 -0.0000333% -1,539,173 Sorption04-035 1 2 1 7 0.159 -0.0000026% -750,237 Sorption04-035 1 2 2 90 0.159 -0.0000307% -804,038 Sorption04-035 1 2 3 91 0.159 -0.0000313% -795,294 Sorption 188 -0.0000646% -797,663 Sorption04-035 2 2 1 7 0.159 -0.0000030% -630,077 Sorption04-035 2 2 2 90 0.159 -0.0000359% -687,312 Sorption04-035 2 2 3 91 0.159 -0.0000374% -667,237 Sorption 188 -0.0000763% -675,195 Sorption04-036 1 2 1 7 0.287 -0.0000005% -3,523,638 Sorption04-036 1 2 2 90 0.287 -0.0000189% -1,301,931 Sorption04-036 1 2 3 91 0.287 -0.0000197% -1,262,661 Sorption 188 -0.0000392% -1,312,989 Sorption04-036 2 2 1 7 0.287 -0.0000017% -1,120,108 Sorption04-036 2 2 2 90 0.287 -0.0000205% -1,205,697 Sorption04-036 2 2 3 91 0.287 -0.0000212% -1,176,251 Sorption 188 -0.0000434% -1,187,922 Sorption04-044 1 3 1 7 0.878 -0.0000010% -1,912,355 Sorption04-044 1 3 2 90 0.878 -0.0000123% -2,012,058 Sorption04-044 1 3 3 90 0.878 -0.0000113% -2,188,197 Sorption 187 -0.0000245% -2,088,908 Sorption04-044 2 3 1 7 0.878 -0.0000003% -5,752,628 Sorption04-044 2 3 2 90 0.878 -0.0000067% -3,663,105 Sorption04-044 2 3 3 90 0.878 -0.0000059% -4,205,365 Sorption 187 -0.0000129% -3,962,923 Sorption04-054 1 2 1 7 17.7 0.0000000% -745,762,297 Sorption04-054 1 2 2 90 17.7 -0.0000004% -60,558,141 Sorption04-054 1 2 3 91 17.7 -0.0000004% -60,699,677 Sorption 188 -0.0000008% -62,776,621 Sorption04-054 2 2 1 7 17.7 0.0000000% -1,390,309,949 Sorption04-054 2 2 2 90 17.7 -0.0000006% -42,001,853 Sorption04-054 2 2 3 91 17.7 -0.0000006% -39,302,048 Sorption 188 -0.0000012% -42,122,262 Sorption04-067 1 2 1 7 0.640 -0.0000010% -2,018,590 Sorption04-067 1 2 2 90 0.640 -0.0000117% -2,114,844 Sorption04-067 1 2 3 91 0.640 -0.0000120% -2,077,249 Sorption 188 -0.0000246% -2,092,795 Sorption04-067 2 2 1 7 0.640 -0.0000011% -1,805,535 Sorption04-067 2 2 2 90 0.640 -0.0000137% -1,805,535 Sorption04-067 2 2 3 91 0.640 -0.0000132% -1,882,177 Sorption 188 -0.0000280% -1,841,838 Sorption04-082 1 4 1 7 0.043 0.161% 11.9 ReleasePage 5 of 9ID No. Replicate BatchTestingPeriodNo. Daysin TestingPeriodTotal Hgon CCB(μg/g)% Hg on CCBReleased OverTesting PeriodYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Testing PeriodExperimentDuration,DaysCumulative % Hg on CCBSorption or Release overExperimentYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Experiment04-082 1 4 2 7 0.043 0.431% 4.45 Release04-082 1 4 3 7 0.043 0.572% 3.35 Release04-082 1 4 4 5 0.043 0.430% 3.18 Release04-082 1 4 5 7 0.043 0.684% 2.81 Release04-082 1 4 6 3 0.043 0.304% 2.71 Release04-082 1 4 7 5 0.043 0.500% 2.74 Release04-082 1 4 8 5 0.043 0.502% 2.73 Release04-082 1 4 9 4 0.043 0.288% 3.80 Release04-082 1 4 10 5 0.043 0.487% 2.81 Release04-082 1 4 11 5 0.043 0.497% 2.75 Release04-082 1 4 12 4 0.043 0.370% 2.96 Release04-082 1 4 13 5 0.043 0.319% 4.29 Release04-082 1 4 14 6 0.043 0.373% 4.41 Release04-082 1 4 15 13 0.043 0.558% 6.38 Release04-082 1 4 16 7 0.043 0.146% 13.1 Release04-082 1 4 17 7 0.043 0.297% 6.47 Release04-082 1 4 18 9 0.043 0.292% 8.44 Release04-082 1 4 19 14 0.043 0.299% 12.8 Release04-082 1 4 20 29 0.043 0.418% 19.0 Release04-082 1 4 21 46 0.043 0.486% 25.9 Release 200 8.41% 6.51 Release04-082 2 4 1 7 0.043 0.183% 10.5 Release04-082 2 4 2 7 0.043 0.419% 4.58 Release04-082 2 4 3 7 0.043 0.593% 3.23 Release04-082 2 4 4 5 0.043 0.446% 3.07 Release04-082 2 4 5 7 0.043 0.694% 2.76 Release04-082 2 4 6 3 0.043 0.314% 2.62 Release04-082 2 4 7 5 0.043 0.536% 2.55 Release04-082 2 4 8 5 0.043 0.494% 2.78 Release04-082 2 4 9 4 0.043 0.300% 3.65 Release04-082 2 4 10 5 0.043 0.493% 2.78 Release04-082 2 4 11 5 0.043 0.510% 2.69 Release04-082 2 4 12 4 0.043 0.377% 2.91 Release04-082 2 4 13 5 0.043 0.321% 4.26 Release04-082 2 4 14 6 0.043 0.349% 4.71 Release04-082 2 4 15 13 0.043 0.550% 6.48 Release04-082 2 4 16 7 0.043 0.140% 13.7 Release04-082 2 4 17 7 0.043 0.288% 6.65 Release04-082 2 4 18 9 0.043 0.266% 9.29 Release04-082 2 4 19 14 0.043 0.294% 13.1 Release04-082 2 4 20 29 0.043 0.394% 20.2 Release04-082 2 4 21 46 0.043 0.419% 30.1 Release 200 8.38% 6.54 Release04-083 1 4 1 7 0.103 0.00272% 706 Release04-083 1 4 2 43 0.103 0.0331% 356 ReleasePage 6 of 9ID No. Replicate BatchTestingPeriodNo. Daysin TestingPeriodTotal Hgon CCB(μg/g)% Hg on CCBReleased OverTesting PeriodYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Testing PeriodExperimentDuration,DaysCumulative % Hg on CCBSorption or Release overExperimentYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Experiment04-083 1 4 3 45 0.103 0.0563% 219 Release04-083 1 4 4 59 0.103 0.0676% 239 Release04-083 1 4 5 46 0.103 0.221% 56.9 Release 200 0.381% 144 Release04-083 2 4 1 7 0.103 0.00305% 629 Release04-083 2 4 2 43 0.103 0.0609% 194 Release04-083 2 4 3 45 0.103 0.0487% 253 Release04-083 2 4 4 59 0.103 0.0712% 227 Release04-083 2 4 5 46 0.103 0.0986% 128 Release 200 0.282% 194 Release05-001 1 3 1 7 <0.01 -0.000116% -16,506 Sorption05-001 1 3 2 90 <0.01 -0.00116% -21,251 Sorption05-001 1 3 3 90 <0.01 -0.00110% -22,437 Sorption 187 -0.00238% -21,567 Sorption05-001 2 3 1 7 <0.01 -0.000105% -18,212 Sorption05-001 2 3 2 90 <0.01 -0.00196% -12,607 Sorption05-001 2 3 3 90 <0.01 -0.00186% -13,287 Sorption 187 -0.00392% -13,080 Sorption05-002 1 3 1 7 <0.01 -0.000153% -12,503 Sorption05-002 1 3 2 90 <0.01 -0.00275% -8,975 Sorption05-002 1 3 3 90 <0.01 -0.00258% -9,546 Sorption 187 -0.00548% -9,343 Sorption05-002 2 3 1 7 <0.01 0.0000577% 33,230 Release05-002 2 3 2 90 <0.01 -0.000685% -35,990 Sorption05-002 2 3 3 90 <0.01 -0.000562% -43,864 Sorption 187 -0.00119% -43,069 Sorption05-003 1 3 1 7 0.565 -0.0000007% -2,744,055 Sorption05-003 1 3 2 90 0.565 -0.0000131% -1,883,252 Sorption05-003 1 3 3 90 0.565 -0.0000096% -2,578,508 Sorption 187 -0.0000234% -2,193,689 Sorption05-003 2 3 1 7 0.565 0.0000000% 49,463,677 Release05-003 2 3 2 90 0.565 -0.0000044% -5,659,177 Sorption05-003 2 3 3 90 0.565 -0.0000029% -8,416,414 Sorption 187 -0.0000072% -7,068,541 Sorption05-004 1 3 1 7 0.332 -0.0000018% -1,076,757 Sorption05-004 1 3 2 90 0.332 -0.0000320% -769,945 Sorption05-004 1 3 3 90 0.332 -0.0000272% -904,992 Sorption 187 -0.0000611% -839,164 Sorption05-004 2 3 1 7 0.332 -0.0000017% -1,151,710 Sorption05-004 2 3 2 90 0.332 -0.0000201% -1,227,580 Sorption05-004 2 3 3 90 0.332 -0.0000192% -1,285,465 Sorption 187 -0.0000409% -1,251,619 Sorption05-009 1 3 1 7 0.032 0.000863% 2,222 Release05-009 1 3 2 45 0.032 0.00672% 1,833 Release05-009 1 3 3 45 0.032 0.00202% 6,102 Release05-009 1 3 4 90 0.032 0.00535% 4,607 Release05-009 1 3 5 44 0.032 0.00817% 1,476 Release05-009 1 3 6 46 0.032 0.000506% 24,928 Release05-009 1 3 7 48 0.032 0.000169% 77,979 Release05-009 1 3 8 43 0.032 0.000117% 100,674 Release05-009 1 3 9 58 0.032 -0.000109% -145,382 Sorption05-009 1 3 10 47 0.032 0.000056% 230,325 Release 473 0.0239% 5,430 Release05-009 2 3 1 7 0.032 0.000816% 2,351 ReleasePage 7 of 9ID No. Replicate BatchTestingPeriodNo. Daysin TestingPeriodTotal Hgon CCB(μg/g)% Hg on CCBReleased OverTesting PeriodYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Testing PeriodExperimentDuration,DaysCumulative % Hg on CCBSorption or Release overExperimentYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Experiment05-009 2 3 2 45 0.032 0.00545% 2,263 Release05-009 2 3 3 45 0.032 0.00158% 7,781 Release05-009 2 3 4 90 0.032 0.00339% 7,265 Release05-009 2 3 5 44 0.032 0.00433% 2,783 Release05-009 2 3 6 46 0.032 0.00279% 4,524 Release05-009 2 3 7 48 0.032 0.000273% 48,232 Release05-009 2 3 8 43 0.032 0.000242% 48,780 Release05-009 2 3 9 58 0.032 -0.000177% -89,646 Sorption05-009 2 3 10 47 0.032 0.000269% 47,862 Release 473 0.0190% 6,833 Release05-013 1 4 1 7 39.0 0.0000001% 28,634,635 Release05-013 1 4 2 90 39.0 0.0000000% 894,186,303 Release05-013 1 4 3 90 39.0 0.0000000% 662,189,135 Release 187 0.0000001% 388,756,048 Release05-013 2 4 1 7 39.0 0.0000000% 71,666,636 Release05-013 2 4 2 90 39.0 0.0000001% 289,972,871 Release05-013 2 4 3 90 39.0 0.0000000% 1,513,153,294 Release 187 0.0000001% 399,977,490 Release05-023 1 4 1 7 12.7 0.0000001% 27,020,806 Release05-023 1 4 2 90 12.7 0.0000001% 217,423,321 Release05-023 1 4 3 90 12.7 0.0000001% 222,884,943 Release 187 0.0000003% 173,663,704 Release05-023 2 4 1 7 12.7 0.0000001% 22,251,582 Release05-023 2 4 2 90 12.7 0.0000001% 192,511,093 Release05-023 2 4 3 90 12.7 0.0000002% 127,036,891 Release 187 0.0000004% 125,457,465 Release05-024 1 4 1 7 35.9 0.0000000% 116,137,574 Release05-024 1 4 2 90 35.9 -0.0000001% -320,866,834 Sorption05-024 1 4 3 90 35.9 0.0000000% -736,059,867 Sorption 187 -0.0000001% -546,002,953 Sorption05-024 2 4 1 7 35.9 0.0000000% 97,478,007 Release05-024 2 4 2 90 35.9 -0.0000001% -418,363,021 Sorption05-024 2 4 3 90 35.9 -0.0000001% -460,332,617 Sorption 187 -0.0000001% -551,909,510 Sorption05-025 1 4 1 7 12.6 0.0000000% -71,585,890 Sorption05-025 1 4 2 90 12.6 -0.0000009% -27,276,514 Sorption05-025 1 4 3 90 12.6 -0.0000008% -31,743,484 Sorption 187 -0.0000017% -30,003,754 Sorption05-025 2 4 1 7 12.6 0.0000000% -86,636,216 Sorption05-025 2 4 2 90 12.6 -0.0000009% -26,038,716 Sorption05-025 2 4 3 90 12.6 -0.0000010% -25,362,355 Sorption 187 -0.0000019% -26,390,978 Sorption05-038 1 4 1 7 0.104 0.0000110% 175,125 Release05-038 1 4 2 90 0.104 0.0000155% 1,590,224 Release05-038 1 4 3 90 0.104 0.0000029% 8,600,047 Release 187 0.0000293% 1,747,138 Release05-038 2 4 1 7 0.104 0.0000004% 4,284,755 Release05-038 2 4 2 90 0.104 -0.0000538% -458,675 Sorption05-038 2 4 3 90 0.104 0.0000002% 117,631,310 Release 187 -0.0000531% -964,820 Sorption05-040 1 4 1 7 44.5 0.0000000% 592,394,110 Release05-040 1 4 2 90 44.5 0.0000000% -839,331,007 Sorption05-040 1 4 3 90 44.5 0.0000000% 722,511,068 Release 187 0.0000000% 6,414,452,894 Release05-040 2 4 1 7 44.5 0.0000000% -105,422,344 SorptionPage 8 of 9ID No. Replicate BatchTestingPeriodNo. Daysin TestingPeriodTotal Hgon CCB(μg/g)% Hg on CCBReleased OverTesting PeriodYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Testing PeriodExperimentDuration,DaysCumulative % Hg on CCBSorption or Release overExperimentYears to Release 100%Hg on CCB at MeasuredRateSorption or Releaseover Experiment05-040 2 4 2 90 44.5 -0.0000003% -83,152,524 Sorption05-040 2 4 3 90 44.5 -0.0000002% -132,626,936 Sorption 187 -0.0000005% -102,334,397 Sorption06-001 1 4 1 7 64.5 0.0000000% -207,793,209 Sorption06-001 1 4 2 90 64.5 -0.0000001% -188,954,213 Sorption06-001 1 4 3 90 64.5 -0.0000001% -196,211,436 Sorption 187 -0.0000003% -193,045,902 Sorption06-001 2 4 1 7 64.5 0.0000000% -851,189,611 Sorption06-001 2 4 2 90 64.5 -0.0000002% -135,031,899 Sorption06-001 2 4 3 90 64.5 -0.0000002% -164,261,871 Sorption 187 -0.0000003% -152,947,977 SorptionPage 9 of 9

# APPENDIX P

ELEVATED-TEMPERATURE VAPOR-PHASE

MERCURY MEASUREMENT FROM COAL

COMBUSTION BY-PRODUCTS

# ELEVATED-TEMPERATURE VAPOR-PHASE

MERCURY MEASUREMENT FROM COAL

COMBUSTION BY-PRODUCTS

Final Report

AAD Document Control

U.S. Department of Energy National Energy Technology Laboratory PO Box 10940, MS 921-143 Pittsburgh, PA 15236-0940

Cooperative Agreement No. DE-FC26-02NT41727 Performance Monitor: Lynn Brickett

Prepared by:

David J. Hassett

Loreal V. Heebink Debra F. Pflughoeft-Hassett

Erick J. Zacher Tera D. Buckley

Energy & Environmental Research Center University of North Dakota

PO Box 9018 Grand Forks, ND 58202-9018

2006-EERC-02-05 February 2006DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United

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ACKNOWLEDGMENT

This report was prepared with the support of the U.S. Department of Energy (DOE) National Energy Technology Laboratory C ooperative Agreement No. DE-FC26-02NT41727 However, any opinions, findings, co nclusions, or recommendations e xpressed herein are those of the authors(s) and do not necessar ily reflect the views of DOE.

EERC DISCLAIMER

LEGAL NOTICE This research report wa s prepared by the Energy & Environmental Research Center (EERC), an agency of the Univ ersity of North Dakota, as an account of work sponsored by DOE. Because of the research natu re of the work performed, neither the EERC nor any of its employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or re presents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or othe rwise does not necessarily consti tute or imply its endorsement or recommendation by the EERC.

NDIC DISCLAIMER

This report was prepared by the Energy & Environmental Research Center (EERC) pursuant to an agreement partially funded by th e Industrial Commission of North Dakota, and neither the EERC nor any of its subcontractor s nor the North Dakota Industrial Commission nor any person acting on behalf of either:(A) Makes any warranty or repr esentation, express or impl ied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or

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Industrial Commission.ELEVATED-TEMPERATURE VAPOR-PHASE MERCURY MEASUREMENT FROM

COAL COMBUSTION BY-PRODUCTS

ABSTRACT

Under an effort funded by the U.S. Depart ment of Energy (DOE) and industry entitled “Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of mercury and other air toxic elements on the management of (coal combustion by-products (CCBs). The EERC is measuring the release of mercury and other air toxic elements under different controlled laboratory conditions and investigating the re lease of these same air toxic elements in select field settings. One of the potential release mechanis ms under investigation, and the subject of this report, is the elevated-t emperature vapor-phase re lease of mercury from

CCBs.

This report includes a summary of the method development and associated results for work performed under this project to assess the release of mercur y from CCBs when exposed to elevated temperatures. The report includes descri ptions of the apparatu s and method developed. It also includes examples of real-time mercury release profiles generated when various fly ash and flue gas desulfurization material samples were subjected to temperatures up to 750°C. A discussion of work performed using the elevated-t emperature releases to speciate mercury on the CCBs is presented. The report summarizes the various technical issu es associated with performing the release experiments and data inte rpretation. A preliminary interpretation of the results generated is included.i TABLE OF CONTENTS

LIST OF FIGURES ................................................................................................................ ........ ii

LIST OF TABLES................................................................................................................. ........iii

EXECUTIVE SUMMARY ........................................................................................................... iv

INTRODUCTION ................................................................................................................... ....... 1

BACKGROUND ..................................................................................................................... ....... 1

OBJECTIVES..................................................................................................................... ............ 4

METHODS ........................................................................................................................ ............. 4 Mercury Desorption Apparatus and Method......................................................................... 4 Mercury Speciation Method.................................................................................................. 6

RESULTS AND DI SCUSSION..................................................................................................... 6 Samples Evaluated for Elevated-Temperature Release......................................................... 6 Elevated-Temperature Release Desorption Curves for Fly Ash ........................................... 7 Elevated-Temperature Release Deso rption Curves for FGD Material ............................... 13 Mercury-Spiked Desorption Curves.................................................................................... 13

CONCLUSIONS.................................................................................................................... ....... 16

REFERENCES ..................................................................................................................... ........ 16

LIST OF SAMPLES TESTED WITH MERCURY THERMAL DESORPTION APPARATUS ......................................................................................Appendix Aii LIST OF FIGURES

1 Mercury desorption curve for an activated carbon sorbent loaded with mercury................. 3

2 Mercury thermal desorption apparatus.................................................................................. 5

3 Typical one-peak mercury desorption curve for fly ash........................................................ 9

4 Typical two-peak mercury desorption curve for fly ash ....................................................... 9

5 Replicate 1 of a reproducible sample mercury desorption curve, using 640.3 mg of sample ............................................................................................................ . 10

6 Replicate 2 of a reproducible sample mercury desorption curve, using 634.2 mg of sample ............................................................................................................ . 10

7 Replicate 1 of an irreproducible sa mple mercury desorption curve, using 788.9 mg of sample ............................................................................................................ . 11

8 Replicate 2 of an irreproducible sa mple mercury desorption curve, using 581.6 mg of sample ............................................................................................................ . 11

9 Mercury desorption curve for an SDA material generated during injection of activated carbon, usin g 458.7 mg of sample................................................................... 14

10 Mercury desorption curve for a baseline (no mercury control) eastern bituminous fly ash, using 855.9 mg of sample....................................................................................... 15

11 Mercury desorption curve for a baseline (no mercury control) eastern bituminous fly ash spiked with 500 ng of mercuric chloride, using 811.1 mg of sample ..................... 15iii LIST OF TABLES

1 Fly Ash Volatilization Results – Hg Concentration.............................................................. 2

2 Summary of Samples Evaluated in Elevated-Tempera ture Mercury Release Experiments ........................................................................................................... .. 6

3 Summary of Fly Ash Mercury Thermal De sorption Curves Generated to Date................... 7

4 Breakdown of Number of Peaks Generated for Fly Ash Mercury Thermal Desorption Curves to Date .................................................................................................... 8

5 Summary of FGD Material Mercury Thermal Desorption Curves Generated to Date....... 13

6 Identified Peak Ranges for FGD Ma terial Mercury Thermal Desorption

Curves to Date................................................................................................................ ..... 13iv ELEVATED-TEMPERATURE VAPOR-PHASE MERCURY MEASUREMENT FROM

COAL COMBUSTION BY-PRODUCTS

EXECUTIVE SUMMARY

Under an effort funded by the U.S. Depart ment of Energy (DOE) and industry entitled “Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of mercury and other air toxic el ements on the management of coal combustion by-products (CCBs). The EERC is measuring the release of mercury and other air toxic elements under different controlled laboratory conditions and investigating the re lease of these same air toxic elements in select field settings. One of the potential release mechanis ms under investigation, and the subject of this report, is the elevated-t emperature vapor-phase re lease of mercury from

CCBs.

Investigation of elevated-t emperature mercury release fr om CCBs at the EERC began in 1999. The constructed apparatus heated an aliquot of CCB from ambient temperature to 750°C at a constant ramp rate. The mercury and mercury compounds desorbed from the CCB were carried with nitrogen to a heated analytical quartz cell operated at 800°C to thermally decompose compounds to form elemental mercury, which was detected by an atomic absorption spectrophotometer.

Early work under a DOE task showed that thermal desorption curves generated for 100%

activated carbon sorbents loaded with mercury indicated a signi ficant level of mercury desorbed from the sorbent with reproducible peaks. Th e curves generated under the early DOE work provided background information for this task.

A variety of CCBs were evaluated for the real-time elevated-temperature release of mercury. The CCBs were primarily fly ash but also included a limited number of flue gas desulfurization (FGD) materials. Most samples ge nerated either one or two mercury peaks with a range of 0–4 peaks. The temperature of the pr imary mercury peak for fly ash samples ranged from 262° to 750°C, with an average of 468°C. Some samples actually continued to show increasing mercury release at 750° C, so the highest peak temper ature at which the mercury was released could not be determined. More sample s collected from mercury emission control tests continued to release mercury at 750°C than those collected under conditions without mercury emission control testing.

The use of elevated-temperature release of mercury was evaluated as a means of determining the speciation of mercury present on CCBs. Results indicated th at the interaction of mercury with the CCBs at elevated temperatures may preclude speciation using this method on these complex materials.

Thermal desorption curves provided a comparative means of evaluating the elevated-temperature release of mercury from a variety of CCBs, but the method and results have not yet yielded an understanding of the mech anism of release over the temperature range

evaluated.1 ELEVATED-TEMPERATURE VAPOR-PHASE MERCURY MEASUREMENT FROM

COAL COMBUSTION BY-PRODUCTS

INTRODUCTION

The stability of merc ury associated with coal combus tion by-products (CCBs) has become a prominent question as the coal-fired utility industry develops and tests mercury emission controls that may consequently increase the mercury associated with CCBs. The reasons for evaluating the release of mercury from CCBs are 1) to determin e if mercury captured on CCBs is stable or if it will be released, thus negating th e purpose of the removal of the mercury from the emissions, and 2) to aid utilities in determining and understanding changes in CCBs associated with mercury control and a ssociated CCB management.

Under an effort funded by the U.S. Depart ment of Energy (DOE) and industry entitled “Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of mercury and other air toxic elements on the ma nagement of CCBs. The EERC is measuring the release of mercury and other air toxic elements under different controlled laboratory conditions and investigating the release of these same air toxi c elements in select field settings. Results will be used to determine if mercury released fr om CCBs, both as currently produced and as produced with mercury and other emission cont rols in place, will impact CCB management practices.

Laboratory tasks were designe d to address three primary pot ential release mechanisms for mercury over the life cycle of CCBs in a variety of management scenarios:

1. Direct leachability of air t oxic constituents from CCBs.

2. Vapor release of mercury from CCBs at ambient and elevated temperatures.

3. Biologically mediated leachability and vapor release of mercury and other air toxic

elements from CCBs.

This report focuses on the results generated from measuring mercury release at elevated temperatures. Elevated-temperature vapor-pha se experiments simulated potential mercury release from high-temperatur e manufacturing processes su ch as wallboard and cement manufacturing. This report is a preliminary summar y of elevated-temperature release results for the ongoing project entitled “Mercury and Ai r Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilization.”

BACKGROUND

Mercury emission controls will result in r eapportioning the mercury that was previously released to the atmosphere into CCBs. The stability of mercury associated with CCBs is an issue that has only recently been under investigation, but has become a prominent question as the industry strives to determine if current manageme nt options for CCBs will need to be modified.2 The release of mercury vapor, both at ambi ent and elevated temperatures, from CCBs resulting from the use of mercury control tech nologies has been eval uated on a limited basis. Samples of CCBs generated under emission contro l conditions were not r eadily available until

DOE initiated field demonstrations of the contro l technologies. However, some work has been accomplished on samples primarily from pilot- scale and short-term tests. Methods of determining the release include measuring the merc ury in the air, capturing the mercury released over extended periods, and eval uating the mercury contents of CCBs at varying periods, which generally require very sensit ive analytical techniques.

Fly ash volatilization studies performed by Schwalb et al. (1) compared total mercury contents of several ash samples as received and after exposure to elevated temperatures (100° and 140°F [37.7° and 60°C]) for 6 months, with tota l mercury concentration measured at 3 and 6

months. Results are shown in Table 1.

Limited information has been reported on the stability of mercury cap tured on sorbents (2). Results of thermal desorption tests indicate that mercury is thermally released from sorbents at temperatures considerably below the peak temp eratures observed for fly ashes. Significant percentages of the mercury captu red on the saturated sorbents we re released upon heating above 135°C (275°F) in nitrogen, carbon dioxide, or flue gas, and 30% –50% of the original mercury capture capacity of the sorbent was regenerated after one or two regene ration cycles. Ambient release of mercury into a low flow rate of ai r was determined by collecting desorbed mercury on a sorbent. After correcting for blank determinations, essentially no mercury was released at ambient temperature (24°C [75°F]) from either of the sorbents tested. These data may be valuable in assessing the potential for re release of mercury from spent sorbents.

Investigation of elevated-t emperature mercury release fr om CCBs at the EERC began in 1999. Most of the thermal curves generated were straightforward, containing only one or two major desorption peaks (3).

In early work performed under a DOE task (4 ), several samples of 100% activated carbon sorbents loaded with mercury were evaluated. Figure 1 shows a desorption curve generated for

one of these sorbents. The deso rption curve indicated that a si gnificant level of mercury was

Table 1. Fly Ash Volatilization Results – Hg Concentration, ppm (1)

3 month 6 month

Plant ID As-Received 100°F 140°F 100°F 140°F

3 0.09 ± 0.02 0.09 0.10 0.12 0.17

6 0.29 ± 0.05 0.34 0.32 0.38 0.34

6 0.19 ± 0.04 0.22 0.25 0.28 0.24

6 0.69 ± 0.11 0.72 0.69 0.69 0.69

4 0.08 ± 0.02 0.11 0.12 0.13 0.12

4 0.08 ± 0.02 0.09 0.10 0.11 0.133 Figure 1. Mercury desorption curve for an ac tivated carbon sorbent lo aded with mercury.

desorbed from the sample and, as noted in Figure 1, five peaks were identified. These five peaks were reproducible. Other sorbent desorption cu rves were similar, and it was hypothesized as described above that there were multiple binding s ites related to several mechanisms of sorption or bonding to additives in the carbon sorbents. At the time these curves were generated, the calibration of the elevated temper ature apparatus had not yet been instituted, so the amount of mercury released was not quantitated.

No further elevated-temperature experime nts were performed on 100% sorbent samples under this project, but the curves generated under the early DOE wo rk provided background

information for this task.

Determination of the speciation of mercury present on CCBs has been attempted at the EERC (5). Samples were spiked with mercuric oxide (HgO) or merc uric chloride (HgCl 2 ) powder. Experimental work was also done on determ ining the thermal curves for devolatilization of HgO and HgCl 2 compounds added to pulverized quartz pow der to simulate an inert matrix. Thermal desorption of HgO produced a sharp, symme tric peak that desorbed at 250°–325°C. The peak from HgCl 2 desorption was less symmetric and deso rbed at temperatures of 200°–250°C. When spiking ash samples with HgO and HgCl 2 , it was found that the co mplex chemistry and/or matrix of the ash sample altered the deco mposition of the mercury compounds. All spiked samples had peak desorption temperatures higher than that of the spike component alone. In all but one sample, the CCBs spiked with HgCl 2 eluted peaks at temperatures lower than the plain CCB. Spiking samples with HgO yielded variable decomposition temperatures. Unfortunately, this delayed desorption was not completely reproducible, making “peak matching” with desorption curves of the mercury compounds without ash difficult and problematic.4 The use of fly ash in cement manufacture has become relatively common in recent years, and the use of FGD gypsum in wallboard has grown to the extent that new wallboard plants are almost exclusively using FGD and other by-pro duct gypsum. The release of mercury in these uses where the CCB is exposed to elevated temp eratures has the poten tial to impact the use applications and these industries. Laborator y information will be the starting point to understanding the impacts.

OBJECTIVES

The primary objective of the vapor-phase subt ask was to evaluate the release of mercury from CCBs at ambient, near-ambient, and elevat ed temperatures to simulate possible mercury release in various disposal a nd utilization scenarios. The el evated-temperature experiments simulated high-temperature manufacturing s cenarios such as wallboard and cement manufacturing. Mercury is more likely to be rel eased at elevated temperatures, and this report only focuses on the elevated-temperature release experiments and results.

The objective of this report is to report on the method development for and results of experiments to evaluate the elevated-temperatu re vapor-phase release of mercury from CCBs.

METHODS

Mercury Desorption Apparatus and Method

Since mercury and mercury compounds are high ly volatile, mercury was expected to be released from CCBs when they were exposed to elevated temperatures. Even mercury that is sorbed on fly ash, flue gas desu lfurization (FGD) material, or sorbents developed to remove mercury in flue gas is expected to have high potential to be released if exposed to high enough temperatures. Instrumental and equipment constrai nts existed for the physical testing of elevatedtemperature release of mercury from CCBs . These constraints were as follows:

• Furnaces available for the experimental apparatus could only achieve maximum temperatures of 750°C.

• Fittings and connecting tubing needed to be heated in order to minimize the loss of mercury in the system.

• Gas flow to remove the mercury from the heated sample cell to the analytical cell

needed to be constant.

• Temperature ramping needed to be contro lled and consistent between sample runs.

The apparatus for the investigation of real-t ime mercury release was constructed as shown in Figure 2. The CCB sample was weighed into a qua rtz tube with quartz wool used to keep the sample in place in the tube. Nominal sample size was approximately 1 gram. The sample tube5 was then placed into a small tube furnace capab le of achieving a maximum temperature of 750°C. The furnace was controlled with a temp erature controller programmed to ramp the furnace from ambient to maximum temperature at a rate of 25°C per minute. In preliminary experiments, the maximum temperature achiev able was 700°C, but an improved furnace was incorporated into the apparatu s to increase the maximum achiev able temperature to 750°C. A nitrogen gas flow of 5 cm 3 /min was introduced into the tube furnace. As the mercury and mercury compounds desorbed from the CCB in the sample tube, the nitrogen flow carried them through the system to the electrica lly heated quartz analy tical cell. The quartz analytical cell was operated at 800°C, allowing the detection of mercury compounds by thermally decomposing compounds to form elemental mercury, which can be detected by atomic absorption spectrophotometer (AAS). The analytical cell was placed in the center-focused beam path of an AAS. A mercury hollow cathode lamp was used as the light source, and the AAS detector was set to the 253.7-nm line for mercury. A Hewlet t Packard 3395 integrator was used for data

collection.

Calibration of the AAS with elemental me rcury vapor sorbed onto gold-coated quartz produced a peak that was very symmetric and well-defined, decomposing at an average temperature of 350°–375°C. Calibration allows quant itation of the amount of mercury desorbed from the sample being evaluated.

Figure 2. Mercury thermal desorption apparatus.6 Mercury Speciation Method

It has been hypothesized that the mercury species associated with fly ash, FGD material, or carbon can be identified using thermal desorption techniques . EERC researchers performed several experiments to confirm or refute this hypothesis. The experiment al design focused on the use of analytical spikes usi ng mercuric chloride and elemental mercury. CCB samples, quartz sand, and quartz powder were all used as a base sample for these evaluations. Mercuric chloride

was dissolved in ether and then added to the ba se samples. Elemental mercury was added in a gaseous form to CCB samples. The spiked sample s were then desorbed us ing the same apparatus and protocol for the mercury rel ease experiments described above.

RESULTS AND DISCUSSION

Samples Evaluated for Elevated-Temperature Release

Mercury thermal desorption curves were generated for 39 CCBs, including 18 samples without mercury control and 18 samples with merc ury control. The sample set included primarily fly ash but also included various types of FGD ma terials. Several sorbents were evaluated under earlier EERC work, and data from some of these samples are included for comparison and discussion purposes. A list of the samples incl uded in the elevated-temperature release experiments is included in Appendi x A. Table 2 lists numbers of each sample type based relative to coal source and mercury control. It was de termined early in the elevated-temperature

Table 2. Summary of Samples Evaluated in Elevated-Temperature Mercury Release Experiments

Coal Type Sample Type Mercury

Control No. of Samples

Tested Total Mercury

Content Range, μg/g Average

Total Mercury,

μg/g Loss on Ignition (LOI), %

Eastern

Bituminous Fly ash Yes 6 0.4–120 31.8 12.61–23.91

Eastern

Bituminous Fly ash No 7 0.01–0.685 0.199 1.07–8.44

Eastern

Bituminous Fly ash Unknown 3 0.362–1.21 0.730 10.49–10.90

Lignite Fly ash Yes 7 0.147–2.22 0.857 1.04–4.21 Lignite Fly ash No 6 <0.01–0.785 0.343 0.34–2.54 Lignite FGD material Yes 1 0.332 0.332 1.12 Lignite FGD material No 0 <0.01 <0.01 0.95 Subbituminous Fly ash Yes 4 0.64–5.5 3.18 2.11–4.14 Subbituminous Fly ash No 2 0.261–0.578 0.420 0.48–1.08

Subbituminous FGD material No 1 0.112 0.112 2.07

Western

Bituminous Fly ash No 1 0.521 0.521 2.467 experiments that total mercury content of <0. 01 μg/g generally did not allow for a desorption curve to be generated with any level of repr oducibility. The absolute quantitation limit of the apparatus was approximately 10 nanograms. Us ing a maximum of 1 gram of sample, the quantitation limit was used to de termine the lower concentrati on limit of 0.01 μg/g. The bulk of the samples evaluated had total mercury conten t of >0.01 μg/g and, after some preliminary attempts to evaluate samples with a lower total mercury content, low mercury samples were

screened out and not evaluated.

Elevated-Temperature Release Desorption Curves for Fly Ash

As already noted, the release of mercury at elevated temperatures was evaluated by heating a sample in a temperature-controlled tube fu rnace and detecting the emitted mercury or mercury compounds with AAS in a t-cell he ated to 800°C. Over the durati on of the project, the apparatus for elevated-temperature release experiments has been modified to increase the achievable maximum temperature from 700° to 750°C. During the developmental stages of this apparatus, it was also determined that good control of gas fl ow was essential for good quantitation. Since the pressure drop across the sample increases as temperature increases, a mass flow controller was added to maintain a constant gas flow. The releas e of mercury from CCBs at temperatures up to 750°C is essentially quantitative. Mercury ther mal desorption curves were generated throughout the project. However, only those generated after the installation of the ma ss flow controller are included in this report to give a better comparison of obtained results. Representative curves are shown in Figures 1–8.

For this project, most samples desorbed were fly ash samples, and most samples generated either one or two mercury peaks with a range of 0–4 peaks. Table 3 summarizes the information on the mercury thermal desorption curves by samp les with and without mercury control testing. The temperature of the primary mercury peak ra nged from 262° to 750°C, with an average of 468°C. Some samples actually continued to show increasing mercury releas e at 750°C, so the highest peak temperature at which the mercury was released could not be determined. More samples from mercury control testing c ontinued to release mercury at 750°C

Table 3. Summary of Fly Ash Mercury Thermal Desorption Curves Generated to Date
Coal Type Mercury

Control No. of Samples

Tested No. of

Peaks

Noted Range of All Peaks,

°C Total Mercury

Content Range, μg/g LOI, %

Eastern

Bituminous Yes 6 1–4 262–750 0.4–120 12.61–23.91

Eastern

Bituminous No 7 0–3 302–750 0.01–0.685 1.07–8.44

Eastern

Bituminous Unknown 3 1–2 351–750 0.362–1.21 10.49–10.90

Lignite Yes 7 1–2 325–632 0.147–2.22 1.04–4.21 Lignite No 6 0–2 334–750 <0.01–0.785 0.34–2.54

Subbituminous Yes 4 1–2 318–750 0.64–5.5 2.11–4.14

Subbituminous No 2 1 333–404 0.261–0.578 0.48–1.08

Western

Bituminous No 1 1 330–335 0.521 2.468 than those without mercury control testing. Although the lowest me rcury absorbance peak occurred at 262°C for a fly ash sample, some sa mples showed mercury release beginning before

250°C.

Examples of desorption curves with one and two peaks are shown in Figures 3 and 4, respectively. As can be seen in these figures, th e single or first peaks te nded to rise relatively sharply at the initiation of the p eak but tailed off with time. In curves where two or more peaks were noted, peaks after the initial peak tended to show slightly less definition and were usually

broader.

Examples of replicate desorption curves ar e noted in Figures 5–8. Figures 5 and 6 are replicate curves for a sample of lignite fly ash generated during merc ury control technology testing and show excellent reproducibility. Figures 7 and 8 are replicate curves for a sample of eastern bituminous fly ash and show relatively poor reproducibility. While replicates were not performed on every sample in the task samp le set (Appendix A), where replicates were performed, results were generally good. Poor replication generally indicated a highly variable sample.

Table 4 presents a breakdown of sample re producibility for replicate mercury thermal desorption curves generated for fly ash. Just over half of the samples show a reproducible number of peaks generated in replicate runs . However, the remaining samples produced an inconsistent number of peaks in replicate runs and are reported as generating a range of peak

numbers.

Table 4. Breakdown of Number of Peaks Generated for Fly Ash Mercury Thermal Desorption Curves to Date No. of Samples with Designated No. of

Peaks Coal Type Mercury

Control No. of Samples

Tested <DL 1 1 2 3 4 1–2 2–3 1–3

Eastern

Bituminous Yes 6 1 1 1 2 1

Eastern

Bituminous No 7 1 1 2 1 2

Eastern

Bituminous Unknown 3 1 2

Lignite Yes 7 5 2 Lignite No 6 1 2 2

Subbituminous Yes 4 3 1

Subbituminous No 2 2

Western

Bituminous No 1 1

1 Detection limit.9 Figure 3. Typical one-peak mercury desorption curve for fly ash.

Figure 4. Typical two-peak mercur y desorption curve for fly ash.10 Figure 5. Replicate 1 of a reproducible sample mercury desorption curve, using 640.3 mg of sample.

Figure 6. Replicate 2 of a reproducible sample mercury desorption curve, using 634.2 mg of sample.11 Figure 7. Replicate 1 of an irreproducible sample mercury desorption curv e, using 788.9 mg of sample.

Figure 8. Replicate 2 of an irreproducible sample mercury desorption curv e, using 581.6 mg of sample.12 Samples that have shown the most variabil ity are those that c ontain activated carbon

sorbents. The nature of the ash–carbon mixture is to sepa rate, with the carbon moving preferentially to the surface of any container in which the sample is stored. The research team was aware of this issue, and it was sometimes eas ily observed in the laboratory handling of the samples; however, even very car eful mixing and sampling were not adequate to alleviate this variability for the small sample size used for th ermal desorption experiments. In later thermal runs, samples containing no visible carbon showed improved reproducibili ty after grinding. We believe that in these samples the carbon particle s may have been coated with ash and, for this reason, could not be easily seen. During grindin g, the carbon particles became evident as black

swirls as the material was bein g ground. The variability of the sample was al so readily noted in experiments to quantitate mercury releases. In some samples with activated carbon present, mercury concentrations determined based on the peaks identified by the integrator (after apparatus calibration) were not consistent. This phenomenon was exacerbated as carbon particles in the individual samples were noted to be larger. It was determined that this problem could be overcome by carefully grinding the samples in a mo rtar and pestle to a llow a more homogeneous samples to be placed in the thermal desorption sample tubes.

An example of the many problems associated with thermal desorption is a fly ash sample containing sulfur-impregnated acti vated carbon. A sample like this would be expected to produce a thermal curve containing more than one peak. The reasons that multiple peaks might occur on a thermal desorption profile include the following:

• Flue gas can contain elemental and oxidi zed mercury. The oxidized mercury may be present as a chloride, oxide, nitrate, or sulfate, and each of these compounds could result in a discreet peak on its vaporization.

• Sorbents may contain other compounds by desi gn as in sulfur- or halogen-impregnated activated carbon, which may cause formation of additional mercury compounds, each releasing at a discreet temperature.

Elemental mercury is known to sorb as an oxidized species on activated carbon. Additives such as sulfur or iodine, for example, could lead to the formation of additional compounds such

as mercuric sulfide or mercuric iodide. Duri ng thermal desorption, there are many additional things that might happen:

• Elemental mercury and mercuric chloride can desorb unchanged.

• Other mercury compounds can decompose in to their components as would happen with mercuric oxide, which would decompose in to oxygen and elemental mercury prior to desorption.

All of these factors combine in practice to produce thermal desorption curves that, while we may not completely understand the process, provide valuable data.13 Elevated-Temperature Release Desorption Curves for FGD Material

Some FGD material samples we re also subjected to the elevated-temperature protocol. A summary of the information on the mercury thermal desorption curves by sample is provided in

Table 5. Table 6 contains a breakdown of the iden tified mercury peaks from several sample runs. The three samples tested showed a wide variety of mercury release profiles.

Figure 9 is an example of a desorption curve for a spray dryer absorber (SDA) material. This sample was collected during demonstrati on of mercury emission control testing using activated carbon injectio n at a lignite-fired power plant. Fly ash is recycled into the SCA system at the power plant where these samples we re obtained, which is relatively common.

FGD materials are difficult to an alyze with the current elevated -temperature release system because of sulfur interferences, moisture, and other possible problems as noted above.

Mercury-Spiked Desorption Curves

Quartz sand and pure quartz powder where spik ed with mercuric chloride as an inert material similar to CCBs. A single sharp peak wa s recorded when the mercuric chloride was added to the quartz sand. However, when mercuric chloride was spiked onto pure quartz powder, a double peak was noted. This sugg ests that matrix effects may make determination of species very unlikely.

Table 5. Summary of FGD Material Mercury Thermal Desorption Curves Generated to

Date

Coal Type Mercury

Control No. of Samples

Tested No. of

Peaks

Noted Range of All Peaks,

°C Total Mercury Content, μg/g LOI, % Lignite Yes 1 1 312–354 0.332 1.12 Lignite No 1 0 NA 1 <0.01 0.95

Subbituminous No 1 2–3 270–695 0.112 2.07

1 Not applicable.

Table 6. Identified Peak Ranges for FG D Material Mercury Thermal Desorption

Curves to Date Coal Type Mercury Control Identified Peak Ranges No. of Samples Tested Lignite Yes 312–354 1 Lignite No NA 1

270–280

430–475 Subbituminous No

695 114 Figure 9. Mercury desorption curve for an SDA mate rial generated during injection of activated carbon, using 458.7 mg of sample.

Additional elevated-temperatu re release experiments were also performed on CCB samples spiked with mercury. All samples used in this ex periment were fly ash, so me of which contained activated carbon from mercury emission control demonstrati ons. The addition of mercuric chloride or elemental mercury to the CCBs resulted in a shift of the mercury release peaks noted previously from the samples without any added mercury. The peak temperatures measured for spiked CCB samples shifted to higher temperatures for some samples and to lower temperatures for other samples.

Figures 10 and 11 are an example of a fly ash sample tested as described earlier compared to a separate aliquot sp iked with mercuric chlo ride. This was done by mixing a single aliquot of the CCB, just less than 2 grams, and dividing it into two small, near ly equal portions. One portion was left untreated while th e other portion was spik ed with 50 μL of an ether solution of mercuric chloride containing 10 ng/μL of mercuric chloride. This is equiva lent to the addition of 370 ng of mercury as mercuric chloride. Sp iking was done in this manner to minimize nonhomogeneity between the two ali quots of sample. Mercuric chlo ride spiking of this fly ash sample produced an additional peak to those noted on the original fly ash sample. The reasons for an additional peak noted in the spiked samp le are the same as why a fly ash sample may release multiple peaks of mercury.15 Figure 10. Mercury desorption curve for a baseline (no mercury control) eastern bituminous fly ash, using 855.9 mg of sample.

Figure 11. Mercury desorption curve for a baseline (no mercury control) eastern bituminous fly ash spiked with 500 ng of mercuric chloride, using 811.1 mg of sample.16 CONCLUSIONS

Thermal desorption curves provided a comparative means of evaluating the elevated-temperature release of mercury from a variety of CCBs, but the method and results have not yet yielded an understanding of the mech anism of release over the temperature range evaluated. The possible scenario s for release are as follows:

• Mercury and mercury compounds, as sorbe d, are being released unchanged during the thermal desorption procedure.

• Mercury compounds are being desorbed by a mechanism of thermal decomposition whereby sorbed compounds such as HgO are thermally decomposed to mercury and oxygen during the thermal desorption.

• Mercury or mercury compounds are chemica lly reacting with the CCB components then thermally desorbed according to the first or second scenario as described above.

The results indicated that the mercury pres ent on CCBs is expected to be released at temperatures between 262° and 750°C. In most cases, all the sorbed mercury will be released, although some samples did retain some mercury after exposure to 750°C. Some samples showed continued release at 750°C so they might not rel ease all their mercury until a higher temperature

is achieved. While not in vestigated under this project, the amount of time the CCB is exposed to certain temperatures may also impact the amount of mercury released. It is recommended that this be investigated, especially for FGD gypsum, which may be exposed to elevated temperatures for short times during the preparation for use in wallboard. The use of fly ash that contains measurable mercury (with or w ithout sorbent carbon) for cement manufactur e has high potential to release that mercury based on the results presented. It is r ecommended that the CCB industry work with cement manufacturers to investigate so lutions that will facilitate maintenance of this market for fly ash.

REFERENCES

1. Schwalb, A.M.; Withum, J.A. The Evolution of Mercury from Coal Combustion Materials and By-Products. Presented at the Mercur y Control Technology R&D Program Review Meeting, Pittsburgh, PA, Aug 12–13, 2003.

2. Carey, T.R.; Richardson, C.F.; Chang, R. St ability of Mercury Captured on Sorbent

Surfaces. Presented at the Air and Waste Ma nagement Association 92nd Annual Meeting and Exhibition, St. Louis, MO, June 20–24, 1999.

3. Laudal, D.L.; Gallagher, J.R.; Hassett, D.J.; Timpe, R.T. Stability of Mercury in Coal Combustion By-Products. 2000 Annual Report of the Center for Air Toxic Metals ; organized and administered through the University of North Dakota Energy & Environmental Research Center, for U.S. Environmental Protection Agency Cont ract No. R 827649-01; 2000; pp 59–68.17 4. Pavlish, J.H. Task 1.2 – Mercury Stability in the Environment; Fi nal Report for U.S. Department of Energy National Ener gy Technology Laboratory, July 1999.

5. Hassett, D.J.; Heebink, L.V.; Gallagher, J.R. ; Laudal, D.L.; Pflughoeft-Hassett, D.F. Stability of Mercury in Coal Combustion By-Products and Sorbents. 2003 Annual Report of the Center for Air Toxic Metals ; organized and administered th rough the University of North Dakota Energy & Environmental Research Ce nter, for U.S. Environmental Protection Agency Contract No. R 827649-01; 2003; pp 103–115.

# APPENDIX A

LIST OF SAMPLES TESTED WITH MERCURY

THERMAL DESORPTION APPARATUSA-1 Table A1. List of Samples Tested with Mercury Thermal Desorption Apparatus

ID No. Sample Type Coal Type Mercury

Control Total Mercury, μg/g LOI, % 02-002 Fly ash Eastern bituminous Yes 30.6 22.17 02-003 Fly ash Eastern bituminous Yes 21.7 19.38 02-004 Fly ash Subbituminous Yes 5.5 2.84 02-005 Fly ash Subbituminous Yes 4.73 4.14 02-007 Fly ash Eastern bituminous Yes 120 23.91 02-069 Fly ash Eastern bituminous Yes 0.634 12.61 02-070 Fly ash Eastern bituminous No 0.193 5.88 02-072 Fly ash Eastern bituminous No 0.16 5.39 02-076 Fly ash Eastern bituminous Yes 0.4 21.15 03-005 Fly ash Eastern bituminous No 0.084 3.60 03-007 Fly ash Eastern bituminous No 0.141 4.41 03-011 Fly ash Eastern bituminous Unknown 0.618 10.49 03-013 Fly ash Eastern bituminous Unknown 0.362 10.90 03-014 Fly ash Eastern bituminous Unknown 1.21 10.88 03-016 Fly ash Lignite No 0.016 0.34 03-018 Fly ash Lignite Yes 0.289 1.17 03-019 Fly ash Lignite Yes 2.22 4.21 03-060 Fly ash Subbituminous Yes 1.86 2.47 03-061 Fly ash Subbituminous No 0.578 1.08 03-062 Fly ash Lignite Yes 0.49 1.29 03-078 Fly ash Lignite No 0.662 1.47 03-079 Fly ash Lignite No 0.785 2.54 03-088 Fly ash Eastern bituminous No 0.01 1.07 04-003 Fly ash Eastern bituminous No 0.685 8.44 04-007 Fly ash Western

bituminous No 0.521 2.46

04-029 Fly ash Subbituminous No 0.261 0.48 04-033 Fly ash Lignite Yes 1.43 1.39 04-035 Fly ash Lignite No 0.159 2.24 04-036 Fly ash Lignite Yes 0.287 2.16 04-054 Fly ash Eastern bituminous Yes 17.7 18.60 04-067 Fly ash Subbituminous Yes 0.64 2.11 05-001 Fly ash Lignite No <0.01 0.9005-002 Fly ash + FGDSDA Lignite No <0.01 0.95

05-003 Fly ash Lignite Yes 0.565 1.0405-004 Fly ash + FGDSDA Lignite Yes 0.332 1.12

05-005 Fly ash Lignite No 0.431 1.29 05-017 Fly ash Lignite Yes 0.717 1.70 05-018 Fly ash Eastern bituminous No 0.123 3.0199-188 Fly ash + FGDSDA Subbituminous No 0.112 2.07

# APPENDIX Q

ELEVATED-TEMPERATURE MERCURY

RELEASE DATATable Q-1. Elevated-Temperature Mercury Release ResultsID No. Run #SampleAmount (mg)Peak 1(°C)Peak 2(°C)Peak 3(°C)Peak 4(°C) Comments Sample Type Hg Control Configuration Fuel Type99-188 1154 765.7 270 475 695FGD-SDA PRB Subbituminous99-188 1181 1018.7 280 440FGD-SDA PRB Subbituminous99-188 1182 1087.1 275 430FGD-SDA PRB Subbituminous02-002 1050 116.1 262 330 411 736Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-002 1051 71 278 352 470 740Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-003 1052 138.7 290 400 519 750 Peak 1 very small Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-003 1053 54.4 390 509 748 additional peak evolved after heated at 750° for extended period Fly Ash + Activated Carbon Post-PrimaryPCD Eastern Bituminous02-004 1054 155.2 318 552Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous02-004 1101 154 334 363 Very close double peakFly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous02-004 2879 257 366 start of curve noticed at end of run Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous02-005 1056 99.5 326Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous02-005 2880 87.8 358 750Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous02-006 1058 53.9 302 very fine double peakFly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous02-006 3015 83.4 702 peak tip not very defined Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous02-007 1060 19.6 400 518Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-007 2877 13.2 433 571 2nd peak is large tailing peakFly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-069 1061 655.2 481 750 high absorbance Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-069 2921 429.5 474 722 750 Hg release continued when held at 750°CFly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-069 2957 442.4 478Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-069 2958 446.8 700 peak was essentially a small bump Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-069 2959 444.4 750Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-069 2960 442 350 685 747 all peaks very small Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-069 2963 520 410 429 543 705Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-069 2965 484.5 415 450 619 739Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-069 2966 488.8 445 597 750Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-070 1062 707.7 473 741Fly Ash Eastern Bituminous02-070 2993 856.4 473Fly Ash Eastern Bituminous02-071 1063 541 427 675Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-072 1064 792.9 411 558 590Fly Ash Eastern Bituminous02-072 2971 770.3 420 645Fly Ash Eastern Bituminous02-072 2973 778 612Fly Ash Eastern Bituminous02-073 1065 636.3 404Fly Ash Eastern Bituminous02-073 2989 912.1 406 524 750 Hg release continued when held at 750°CFly Ash Eastern Bituminous02-074 1068 606.2 399Fly Ash Eastern Bituminous02-074 3016 706.2 750Fly Ash Eastern Bituminous02-076 1069 710.5 405 750 Hg release continuing at 750°C Fly Ash South American Bituminous02-076 1070 741 417 750Fly Ash South American Bituminous02-076 2990 709.1 386 602Fly Ash South American Bituminous02-076 2997 735.3 356 750 Hg release continued when held at 750°CFly Ash South American Bituminous02-076 2999 722.2 358 708 750 Hg release continued when held at 750°CFly Ash South American Bituminous02-076 3000 722.5 396 750Fly Ash South American Bituminous02-076 3006 702.6 365 750Fly Ash South American Bituminous02-076 3028 363.7 361 750Fly Ash South American Bituminous03-004 1071 994.7 378 720Fly Ash Eastern Bituminous03-004 3014 1070.2 537Fly Ash Eastern Bituminous03-005 1072 956.4 384 711Fly Ash Eastern Bituminous03-005 1080 530.2 376 750 Hg release continuing at 750°C Fly Ash Eastern Bituminous03-006 1073 767.7 443Fly Ash Eastern Bituminous03-006 2987 894 450Fly Ash Eastern BituminousPage 1 of 7ID No. Run #SampleAmount (mg)Peak 1(°C)Peak 2(°C)Peak 3(°C)Peak 4(°C) Comments Sample Type Hg Control Configuration Fuel Type03-006 2988 884.1 412 575 625Fly Ash Eastern Bituminous03-007 1074 788.9 435 740Fly Ash Eastern Bituminous03-007 1102 936.2 452 527 718Fly Ash Eastern Bituminous03-007 1103 581.6 522Fly Ash Eastern Bituminous03-008 1075 942.8 362Fly Ash South American Bituminous03-016 1082 1001.1 368Fly Ash Fort Union Lignite03-016 2904 408.1 354Fly Ash Fort Union Lignite03-016 2905 964.8 383 very small bump Fly Ash Fort Union Lignite03-017 1083 697.1 350 slight peak start at end of run Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-018 1084 649.2 325Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-018 1085 649.3 335Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-018 1108 438.1 350Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-018 1200 616.4 346Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-018 1202 647.6 339 slight increase at end of run Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-018 2931 638.8 358Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-018 2932 639.5 363Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-019 1086 221.2 375Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-019 1250 186.1 382Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-019 1251 167.1 375Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-060 1087 197.6 395Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous03-060 1247 202.4 400Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous03-060 1248 196.3 392Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous03-061 1088 556.7 383Fly Ash PRB Subbituminous03-061 2908 269.4 404Fly Ash PRB Subbituminous03-061 2926 276.9 378Fly Ash PRB Subbituminous03-062 1089 629.7 334Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-062 1230 595.8 358Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-062 1231 596.3 357 sharp peak Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-062 1239 598.2 346 sharp peak Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-062 2933 603 398Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-062 2934 604.8 368 ground sample Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-062 2935 602.7 361Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-062 2942 606.3 331Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-062 2943 604.4 333 jagged peak Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-062 2945 600 356Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-063 1090 990.1 675 no real peak Fly Ash Eastern Bituminous03-065 1111 1000.9 329FGD Gypsum Eastern Bituminous03-078 1044 494.6 350Fly Ash Fort Union Lignite03-078 1120 498.4 334Fly Ash Fort Union Lignite03-078 1171 505.7 355 jagged top of peak Fly Ash Fort Union Lignite03-079 1043 236.7 356Fly Ash Fort Union Lignite03-079 1121 465.4 361 750 peak not complete at end of run Fly Ash Fort Union Lignite03-079 2916 506.1 345Fly Ash Fort Union Lignite03-080 1122 677.4 380 443 slight increase at end of run Fly Ash Fort Union Lignite03-080 3018 1105 750Fly Ash Fort Union Lignite03-080 3019 1044.7 347Fly Ash Fort Union Lignite03-081 1123 641.3 275 346 592Fly Ash Fort Union Lignite03-081 2984 479.5 296 750 peak not complete at end of run Fly Ash Fort Union Lignite03-083 1124 1005.9 413 very broad peakFly Ash Eastern Bituminous03-083 3021 1364.2 358Fly Ash Eastern BituminousPage 2 of 7ID No. Run #SampleAmount (mg)Peak 1(°C)Peak 2(°C)Peak 3(°C)Peak 4(°C) Comments Sample Type Hg Control Configuration Fuel Type03-084 1125 750.1 256 460 720Fixated FGD Eastern Bituminous03-085 1126 1003.5 354 748Fly Ash Eastern Bituminous03-085 3020 1558.2 392 750Fly Ash Eastern Bituminous03-088 1127 1862.8 273 350 551 747Fly Ash Eastern Bituminous03-088 1173 1323.1 742Fly Ash Eastern Bituminous03-088 1175 1315 487 737 all peaks very small Fly Ash Eastern Bituminous03-088 1177 1327.8 285 750 all peaks very small Fly Ash Eastern Bituminous03-089 1128 756.8 298FGD Gypsum Eastern Bituminous04-003 1129 467.7 434Fly Ash Eastern Bituminous04-003 1178 507.7 393 750Fly Ash Eastern Bituminous04-003 1180 504.8 449Fly Ash Eastern Bituminous04-003 2918 253 444Fly Ash Eastern Bituminous04-004 1130 1606.1 300Fly Ash Eastern Bituminous04-006 1131 752.1 378Fly Ash Western Bituminous04-007 1132 620.5 330Fly Ash Western Bituminous04-007 2954 626.7 335Fly Ash Western Bituminous04-029 1133 623.5 352Fly Ash PRB Subbituminous04-029 2910 317.3 333 very small peakFly Ash PRB Subbituminous04-030 1143 1308.5 397 750 peak not complete at end of run Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite04-030 3013 1011.2 563Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite04-031 3010 890 555Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite04-032 1145 788.2 448 572 747Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite04-032 3009 806.3 318 576Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite04-033 1149 293.5 477Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite04-033 2867 251.4 632Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite04-033 2868 284.9 499 603Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite04-033 2883 251.3 528Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite04-035 1150 715 336Fly Ash Fort Union Lignite04-035 1209 558.2 356Fly Ash Fort Union Lignite04-035 1215 623.5 362Fly Ash Fort Union Lignite04-035 2912 852 370 sample had visible unburned C particles Fly Ash Fort Union Lignite04-035 2936 768.6 341 jagged peak Fly Ash Fort Union Lignite04-035 2940 771.2 365Fly Ash Fort Union Lignite04-035 2941 769.4 353 jagged peak Fly Ash Fort Union Lignite04-036 1151 619.7 336Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union Lignite04-036 1203 640.3 360Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union Lignite04-036 1204 634.2 368Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union Lignite04-036 2946 635.2 339Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union Lignite04-036 2947 632.5 344Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union Lignite04-036 3022 704.8 324 750Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union Lignite04-036 3023 885.9 324 ground sampleFly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union Lignite04-036 3025 711.8 330Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union LignitePage 3 of 7ID No. Run #SampleAmount (mg)Peak 1(°C)Peak 2(°C)Peak 3(°C)Peak 4(°C) Comments Sample Type Hg Control Configuration Fuel Type04-054 1153 60.5 385 435 720Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous04-054 1190 99.4 490Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous04-054 1191 115.4 477Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous04-054 1193 104.3 344 500 750 peak not complete at end of run Fly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous04-067 1206 543.9 377 high absorbanceFly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union Lignite04-067 1207 482.3 397 high absorbanceFly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union Lignite04-067 2884 374.1 433Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union Lignite04-067 2928 504.1 422 sharp peakFly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union Lignite05-001 1211 532.8 no real peak recorded Fly Ash Fort Union Lignite05-001 2861 1033.1 289 442Fly Ash Fort Union Lignite05-001 2862 1179.5 459Fly Ash Fort Union Lignite05-002 1228 453.9 no real peak recorded FGD-SDA Fort Union Lignite05-003 1223 490.9 335Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI before SDA Fort Union Lignite05-003 1225 474.8 345Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI before SDA Fort Union Lignite05-003 1226 496.6 329Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI before SDA Fort Union Lignite05-003 2890 206.5 385 broad tailingFly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI before SDA Fort Union Lignite05-004 1217 458.7 318 487FGD-SDA + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI before SDA Fort Union Lignite05-004 2891 287.8 354FGD-SDA + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI before SDA Fort Union Lignite05-004 2953 291.9 312FGD-SDA + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI before SDA Fort Union Lignite05-005 1219 405.3 365Fly Ash Fort Union Lignite05-005 1220 428.3 377Fly Ash Fort Union Lignite05-005 2892 265.2 384Fly Ash Fort Union Lignite05-005 2924 520.5 379 all peaks small; sample run through 100-mesh sieve Fly Ash Fort Union Lignite05-005 3030 778.7 332 sample run through 100-mesh sieve Fly Ash Fort Union Lignite05-005 3034 729.2 316 sample run through 100-mesh sieve Fly Ash Fort Union Lignite05-005 3042 673.4 316 sample run through 100-mesh sieve Fly Ash Fort Union Lignite05-010 2864 782.1 328 393 broad curve with two peaks Fly Ash Eastern Bituminous05-010 2865 762.9 311Fly Ash Eastern Bituminous05-010 3007 777.1 334 750Fly Ash Eastern Bituminous05-013 3075 6.2 423Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite05-013 3076 4.8 457 751Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite05-013 3077 5.6 451 526 very jagged Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite05-017 2853 341.8 417 578Fly Ash + Enhancing AgentEnhancing Agent on Coal Fort Union Lignite05-017 2854 523.5 405 561Fly Ash + Enhancing AgentEnhancing Agent on Coal Fort Union Lignite05-017 2858 338 403 590Fly Ash + Enhancing AgentEnhancing Agent on Coal Fort Union Lignite05-017 2863 320.5 406Fly Ash + Enhancing AgentEnhancing Agent on Coal Fort Union Lignite05-017 3039 485 391 684Fly Ash + Enhancing AgentEnhancing Agent on Coal Fort Union Lignite05-017 3040 560 399Fly Ash + Enhancing AgentEnhancing Agent on Coal Fort Union Lignite05-017 3041 403.5 393 666Fly Ash + Enhancing AgentEnhancing Agent on Coal Fort Union LignitePage 4 of 7ID No. Run #SampleAmount (mg)Peak 1(°C)Peak 2(°C)Peak 3(°C)Peak 4(°C) Comments Sample Type Hg Control Configuration Fuel Type05-018 2855 788.4 317 747 1st peak high absorbance; Hg release continuing at 750°C Fly Ash Eastern Bituminous05-018 2857 787.4 340 703Fly Ash Eastern Bituminous05-018 2995 822.7 302 564 643 3rd peak on tail of 2nd peak Fly Ash Eastern Bituminous05-018 3003 855.9 317 581Fly Ash Eastern Bituminous05-023 3046 167.2 497 749 high absorbance Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-023 3048 55.5 454 746 750 great amount of Hg release after 750°C reached Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-023 3050 86.9 471 high absorbance Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-023 3053 102.1 471 high absorbance Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-023 3054 75.5 469 high absorbance; Hg release continued when held at 750°C Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-023 3059 102.1 441 682Sx in 1008.5 mg quartz sand; high absorbance; Hg releasecontinued when held at 750°C Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-023 3062 29 388 Sx in 1002.8 mg quartz sand Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-023 3063 32.8 460 586 Hg release continuing at 750°C Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-023 3065 19.6 459 577Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-023 3067 13.7 468Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-024 3071 16.2 436 high absorbance Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite05-024 3072 9.2 444Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite05-024 3073 8.5 443Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite05-025 3068 31.2 437Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-025 3069 18.6 353 430 704Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-025 3070 20.7 438 684Fly Ash + Activated CarbonPost-Primary PCD: High FlyAsh Content Fort Union Lignite05-038 3056 941.6 376 697 Hg release continuing at 750°C Fly Ash Fort Union Lignite05-040 3078 2.9 427Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite05-040 3079 2.2 447 750Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite06-001 3080 1.3 385Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite06-001 3081 1.2 423Fly Ash + Activated Carbon Post-Primary PCD Fort Union LigniteQuartz Sand 3058 1008.5 no peaks Quartz SandQuartz Sand 3084 494 no peaks Quartz SandQuartz Sand 3090 495.8 no peaks Quartz SandQuartz Sand 3108 531.9 no peaks Quartz SandFly Ash Std. 1139 526.9 292NIST 1633b Fly Ash StandardFly Ash Std. 2951 806.4 450 750 all peaks very small NIST 1633b Fly Ash StandardPage 5 of 7Table Q-2. Elevated-Temperature Mercury Release Results for Mercury Spiked SamplesID No. Run #SampleAmount (mg) Spiked withPeak 1(°C)Peak 2(°C)Peak 3(°C)Peak 4(°C) Comments Sample Type Hg Control Configuration Fuel Type02-004 1099 155.6HgCl2in ether307 plateau noted half way down tail of peakFly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous02-004 1100 157.5HgCl2in ether307 plateau noted half way down tail of peakFly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous02-069 2968 494.7HgCl2in ether306 419 698 750 Hg release continued when held at 750°CFly Ash + Activated Carbon Post-Primary PCD Eastern Bituminous02-070 2994 778.6HgCl2in ether483 596Fly Ash Eastern Bituminous02-076 2991 713.4HgCl2in ether364 651Fly Ash South American Bituminous02-076 3001 722HgCl2in ether410 750Fly Ash South American Bituminous02-076 3002 760.3HgCl2in ether401Fly Ash South American Bituminous02-076 3027 614.3HgCl2in ether367Fly Ash South American Bituminous03-007 1104 593.1HgCl2in ether597Fly Ash Eastern Bituminous03-007 1105 581.6 Hg0403 577 1st peak very sharp, 2nd peak broad Fly Ash Eastern Bituminous03-007 1106 548.8 Hg0406 572 1st peak very sharp, 2nd peak broad Fly Ash Eastern Bituminous03-007 1107 573.9HgCl2in ether431 750 Hg release continued when held at 750°CFly Ash Eastern Bituminous03-016 2907 458.6HgCl2in ether315Fly Ash Fort Union Lignite03-018 1109 438.8 Hg0350Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-018 1110 436.3HgCl2in ether323Fly Ash + Activated Carbon Pre-Primary PCD Fort Union Lignite03-061 2909 222.4HgCl2in ether387 broad peak with narrow lip at topFly Ash PRB Subbituminous03-061 2927 277HgCl2in ether392Fly Ash PRB Subbituminous03-063 1096 975.2HgCl2in ether307 450 very broad; 2nd peak on tail of 1st peakFly Ash Eastern Bituminous03-063 1097 479.4HgCl2in ether260 tailing peakFly Ash Eastern Bituminous03-081 2985 454.2HgCl2in ether320 664 Hg release continued when held at 750°CFly Ash Fort Union Lignite04-029 2911 331.8HgCl2in ether361 jagged peak Fly Ash PRB Subbituminous04-033 2887 105HgCl2in ether331 475 498 all peaks very small Fly Ash + Activated Carbon Post-Primary PCD Fort Union Lignite04-035 2914 892.5HgCl2in ether351Fly Ash Fort Union Lignite04-036 3024 777.1HgCl2in ether307 750FlyAsh+EnhancingAgent +Activated CarbonEnhancingAgent onCoal,ACI Pre-Primary PCD Fort Union Lignite04-036 3026 774.2HgCl2in ether306FlyAsh+EnhancingAgent +Activated CarbonEnhancingAgent onCoal,ACI Pre-Primary PCD Fort Union Lignite04-067 2903 393.9HgCl2in ether388FlyAsh+EnhancingAgent +Activated CarbonEnhancingAgent onCoal,ACI Pre-Primary PCD Fort Union Lignite04-067 2929 506.7HgCl2in ether407 750FlyAsh+EnhancingAgent +Activated CarbonEnhancingAgent onCoal,ACI Pre-Primary PCD Fort Union Lignite05-003 2899 205.7HgCl2in ether370FlyAsh+EnhancingAgent +Activated CarbonEnhancingAgent onCoal,ACI before SDA Fort Union Lignite05-004 2900 298HgCl2in ether321FGD-SDA+EnhancingAgent +Activated CarbonEnhancingAgent onCoal,ACI before SDA Fort Union Lignite05-005 2901 271HgCl2in ether376Fly Ash Fort Union Lignite05-005 2923 519HgCl2in ether377 sample run through 100-mesh sieve Fly Ash Fort Union Lignite05-010 3008 770.4HgCl2in ether286 382 750 Fly Ash Eastern Bituminous05-018 2996 885.6HgCl2in ether317 583Fly Ash Eastern Bituminous05-018 3004 811.1HgCl2in ether313 496 569 Fly Ash Eastern Bituminous05-038 3055 800HgCl2in ether339 711Fly Ash Fort Union LigniteBlank Tube 2889 1HgCl2in etherPage 6 of 7ID No. Run #SampleAmount (mg) Spiked withPeak 1(°C)Peak 2(°C)Peak 3(°C)Peak 4(°C) Comments Sample Type Hg Control Configuration Fuel TypeBlank Tube 2969 1HgCl2in ether408Blank Tube 2978 1HgCl2in ether287Blank Tube 2979 1HgCl2in ether132 228 very jaggedBlank Tube 2980 1HgCl2in ether203 237 315 very jaggedQuartzPowder 1093 513.6HgCl2in ether218 260Quartz PowderQuartzPowder 1094 501.1HgCl2in ether219Quartz PowderQuartz Sand 1092 511.2HgCl2in ether268Quartz SandQuartz Sand 1095 507.2HgCl2in ether264Quartz SandQuartz Sand 2894 1009.5HgCl2in ether175 218Quartz SandQuartz Sand 2895 1003.6HgCl2in ether285Quartz SandQuartz Sand 2896 1014.4HgCl2in ether270Quartz SandQuartz Sand 3085 492.2HgCl2in ether209Quartz SandQuartz Sand 3086 460.4HgCl2in ether189 750Quartz SandQuartz Sand 3087 501.6HgCl2in ether213 240 713 Quartz SandQuartz Sand 3089 477.4HgCl2in ether193 236 very jagged Quartz SandQuartz Sand 3091 487HgCl2in ether173Quartz SandQuartz Sand 3092 497.2HgCl2in ether168 202 662 734 very jagged Quartz SandQuartz Sand 3093 495.2HgCl2in ether216Quartz SandQuartz Sand 3097 471.1HgCl2in ether191 228 very jagged Quartz SandQuartz Sand 3098 488HgCl2in ether200 very jagged Quartz SandQuartz Sand 3101 488.1HgCl2in ether199Quartz SandQuartz Sand 3102 478.6HgCl2in ether207 691 Hg release continued at 750°C Quartz SandQuartz Sand 3104 478.8HgCl2in ether199Quartz SandQuartz Sand 3105 482.2HgCl2in ether204Quartz SandQuartz Sand 3106 470.2HgCl2in ether190Quartz SandQuartz Sand 3109 489.5HgCl2in ether152 183Quartz SandQuartz Sand 3110 489.3HgCl2in ether197Quartz SandQuartz Sand 3111 496.6HgCl2in ether188Quartz SandQuartz Sand 3112 453.1HgCl2in ether202Quartz SandQuartz Sand 3113 476.1HgCl2in ether197Quartz SandPage 7 of 7

# APPENDIX R

MICROBIOLOGICALLY MEDIATED MERCURY

AND AIR TOXIC ELEMENT RERELEASES

FROM COAL COMBUSTION BY-PRODUCTS

# MICROBIOLOGICALLY MEDIATED MERCURY

AND AIR TOXIC ELEMENT RERELEASES FROM

COAL COMBUSTION BY-PRODUCTS

Final Report

AAD Document Control

U.S. Department of Energy National Energy Technology Laboratory PO Box 10940, MS 921-143 Pittsburgh, PA 15236-0940

Cooperative Agreement No. DE-FC26-02NT41727 Performance Monitor: Lynn Brickett

Prepared by:

Debra F. Pflughoeft-Hassett

David J. Hassett John R. Gallagher

Loreal V. Heebink

Erick J. Zacher Rob Jung Tera D. Buckley

Energy & Environmental Research Center University of North Dakota

PO Box 9018 Grand Forks, ND 58202-9018

2006-EERC-02-04 February 2006DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United

States Government. Neither the United States G overnment, nor any agency thereof, nor any of their employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not n ecessarily constitute or imply its endorsement, recommendation, or favoring by the United States G overnment or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

This report is available to th e public from the National Techni cal Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springf ield, VA 22161; phone orders accepted at (703) 487-4650.

ACKNOWLEDGMENT

This report was prepared with the support of the U.S. Department of Energy (DOE) National Energy Technology Laboratory Coop erative Agreement No. DE-FC26-02NT41727. However, any opinions, findings, co nclusions, or recommendations e xpressed herein are those of the authors(s) and do not necessar ily reflect the views of DOE.

EERC DISCLAIMER

LEGAL NOTICE This research report was prepared by the EERC, an agency of the University of North Dakota, as an account of work sponsored by DOE. Because of the research nature of the work performed, neither the EERC nor any of its employees makes any warranty, express or implied, or assumes any legal li ability or responsibili ty for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademar k, manufacturer, or otherwise does not necessarily constitute or imply its endorsement or recommendation by the EERC.

NDIC DISCLAIMER

This report was prepared by the EERC pursuan t to an agreement pa rtially funded by the Industrial Commission of North Dakota, and neith er the EERC nor any of its subcontractors nor

the North Dakota Industrial Commission nor any person acting on behalf of either:

(A) Makes any warranty or repr esentation, express or impl ied, with respect to the accuracy, completeness, or usefulness of the information contained in this report, orthat the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or

(B) Assumes any liabilities with respect to the use of, or for damages resulting from the use of, any information, apparatus, method, or process disclosed in this report.

Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not n ecessarily constitute or imply its endorsement, recommendation, or favoring by the North Da kota Industrial Commission. The views and opinions of authors expressed here in do not necessarily state or reflect those of the North Dakota

Industrial Commission.MICROBIOLOGICALLY MEDIATED ME RCURY AND AIR TOXIC ELEMENT

RERELEASES FROM COAL COMBUSTION BY-PRODUCTS

ABSTRACT

Under an effort funded by the U.S. Depart ment of Energy (DOE) and industry entitled “Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of mercury and other air toxic el ements on the management of coal combustion by-products (CCBs). The EERC is measuring the release of mercury and other air toxic elements under different controlled laboratory conditions and investigating the re lease of these same air toxic elements in select field settings. One of the potential release mechanis ms under investigation, and the subject of this report, is the biologica lly mediated leachability and vapor release of mercury and other air toxic elements from CCBs.

This report includes a summary of the method development over the course of this project

and the associated results. It also summarizes the various technical issues associated with performing the release experiments and the analys es of the mercury released in both the vapor and liquid phases. A preliminary interpretation of the results generated is also included, but a final data analysis and interpretation will be incl uded in the final report for the ongoing project.i TABLE OF CONTENTS

LIST OF FIGURES ................................................................................................................ ........ ii

LIST OF TABLES................................................................................................................. ........iii

EXECUTIVE SUMMARY ........................................................................................................... iv

INTRODUCTION ................................................................................................................... ....... 1

BACKGROUND ..................................................................................................................... ....... 2

OBJECTIVES..................................................................................................................... ............ 3

METHODS ........................................................................................................................ ............. 3 Description of Initial Apparatus and Method........................................................................ 4 Modifications of the Apparatu s and Experimental Design ................................................... 5 CCB Preparation Methods .................................................................................................... 5 Microbiological Innoculum Growth Conditions and Media................................................. 6 Experimental Incubation Conditions..................................................................................... 6 Mercury Analyses ............................................................................................................... .. 8 Microbiological Analysis ...................................................................................................... 8

RESULTS AND DI SCUSSION..................................................................................................... 9 Microbiologically Mediated Release of Mercury from CCBs – Experiment 1 .................... 9 Microbiologically Mediated Release of Mercury from CCBs – Experiment 2 .................. 10 Microbiologically Mediated Release of Mercury from CCBs – Experiment 3 .................. 11 Microbiologically Mediated Rele ase of Mercury and Air Toxic Elements from CCBs – Experiment 4 ................................................................................. 12 Microbiologically Mediated Rele ase of Mercury and Air Toxic Elements from CCBs – Experiment 5 ................................................................................. 15 Microbiologically Mediated Release of Mercury from CCBs – Experiment 6 .................. 18

OBSERVATIONS AND CONCLUSIONS ................................................................................. 19

REFERENCES ..................................................................................................................... ........ 20

MICROBIOLOGICAL SAMPLE SET .........................................................................Appendix Aii LIST OF FIGURES

1 Early microbiologically mediated mercury vapor-phase collection apparatus utilizing a wrist action shaker to facilitate mixing................................................ 4

2 Current microbiologically mediated mercury vapor-phase collection apparatus utilizing a stir pl ate to facilitate mixing ................................................................ 6

3 Summary of microbiological results ................................................................................... 18iii LIST OF TABLES

1 Microbiological Rerelease Apparatus Modifications............................................................ 5

2 Experimental Incubation Conditions..................................................................................... 7

3 CCB Sample Description and Total Me rcury Content, Experiment 1.................................. 9

4 Results of Microbiologically Released Me rcury from Sample 99-188, Experiment 1....... 10

5 CCB Sample Description and Total Me rcury Content, Experiment 2................................ 11

6 Results of Microbiologically Released Me rcury from Sample 01-002, Experiment 2....... 11

7 CCB Sample Description and Total Me rcury Content, Experiment 3................................ 12

8 Results of Microbiologically Me diated Release of Vapor-Phase Mercury and Total Bact erial Counts for Sample 03-060, Experiment 3 ............................ 12

9 CCB Sample Description and Total Me rcury Content, Experiment 4................................ 13

10 Initial Elemental Mercury Release, Experiment 4 .............................................................. 13

11 Results Including Eh, pH, and Ending Sa mple Description, Experiment 4........................ 14

12 Vapor-Phase Mercury Release Results, Experiment 4........................................................ 15

13 Solution Organomercury Results, Experiment 4................................................................. 16

14 Leached Total Trace Element Results, Experiment 4 ......................................................... 16

15 Samples Included in Microbiolog ical Release Experiment 5 ............................................. 16

16 Microbiological Eh and pH Results, Experiment 5............................................................. 17

17 Vapor-Phase Mercury Release Results, Experiment 5........................................................ 17

18 Microbiological Leached Total Trace Element Results...................................................... 18

19 Microbiological Buffer Total Trace Element Results ......................................................... 18

20 Samples Included in Microbiolog ical Release Experiment 6 ............................................. 19iv MICROBIOLOGICALLY MEDIATED ME RCURY AND AIR TOXIC ELEMENT

RERELEASES FROM COAL COMBUSTION BY-PRODUCTS

EXECUTIVE SUMMARY

Under an effort funded by the U.S. Depart ment of Energy (DOE) and industry entitled “Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of mercury and other air toxic el ements on the management of coal combustion by-products (CCBs). The EERC is measuring the release of mercury and other air toxic elements under different controlled laboratory conditions and investigating the re lease of these same air toxic elements in select field settings. One of the potential release mechanis ms under investigation, and the subject of this report, is the biologica lly mediated leachability and vapor release of mercury and other air toxic elements from CCBs.

The EERC’s method to evaluate the mercury release potential from CCBs by leaching and offgassing under microbiologically mediated c onditions has undergone several modifications since it was first developed in 1999 . The current apparatus uses a 9- place stir plate to facilitate mixing of the CCB, a buffer, and microbes. An improved buffer uses 100 ppm of phosphate and potassium glutamate as the nitrogen source. Ea rly experiments with starved microbes did not promote microbial growth; therefor e, all samples in later experime nts were fed with glucose. An

innoculum from a local brackish wetland added to 10 mL of 0.9% NaCl and vortexed was introduced to the samples. Sulfuric acid was added to neutralize alkaline samples prior to introducing the microbes. The sample mixtures were allowed to incubate in sealed flasks at room temperature for 4 weeks. Experiments were all performed in triplicate.

Several methods were used to collect, measure, and speciate the mercury release from CCBs. Vapor-phase organomercury compounds were trapped on Supelco CarbotrapTM collection traps, with the remaining mercury collected on gold-coated quartz collection traps. The CarbotrapTM collection traps were analyzed for total mercury by heating the trap to approximately 300°C, passing the released orga nomercury through a tube at about 800°C, and collecting the mercury vapor on a gold-coated quartz trap. All gold-coated quartz traps were desorbed for analysis by heating to approxima tely 500°C and determining the mass of mercury released with atomic fluorescence (AF). Total me rcury concentrations of the leachate were determined using cold-vapor atomic fluor escence spectroscopy (CVAFS). Solid-phase microextraction (SPME) was used to determine or ganomercury species of the mercury present in leachates. The air toxic element—arsenic, cadmium, chromium, lead, nickel, and selenium—

concentrations of the leachate were determined by inductively coupled plasma (ICP) and ICP– mass spectrometry (ICP–MS).

A variety of CCB samples were evaluated for microbiologically mediated mercury releases using the methods described. Aerobic and anaer obic glucose-fed conditions were used in the experiments on fly ash and wet limestone flue gas desulfurization (FGD) filter cake material.The fly ash samples evaluated were from eastern bituminous, subbituminous, and lignite coalfired power plants, with total mercury cont ents ranging from 0.004–1.86 μg /g. The FGD materialv had a 0.218-μg/g mercury content and a signifi cant natural population of sulfate-reducing bacteria. Data collected to date are variable, a nd work will continue on the experimental release method and the analytical methods.1 MICROBIOLOGICALLY MEDIATED ME RCURY AND AIR TOXIC ELEMENT

RERELEASES FROM COAL COMBUSTION BY-PRODUCTS

INTRODUCTION

The stability of merc ury associated with coal combus tion by-products (CCBs) has become a prominent question as the coal-fired utility industry develops and tests mercury emission controls that may consequently increase the mercury associated with CCBs. The reasons for evaluating the release of mercury from CCBs are 1) to determin e if mercury captured on CCBs is stable or if it will be released, thus negating th e purpose of the removal of the mercury from the emissions, and 2) to aid utilities in determining and understanding changes in CCBs associated with mercury control and a ssociated CCB management.

Under an effort funded by the U.S. Depart ment of Energy (DOE) and industry entitled “Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilization,” the Energy & Environmental Research Center (EERC) is evaluating the impact of mercury and other air toxic elements on the ma nagement of CCBs. The EERC is measuring the release of mercury and other air toxic elements under different controlled laboratory conditions and investigating the release of these same air toxi c elements in select field settings. Results will be used to determine if mercury released fr om CCBs, both as currently produced and as produced with mercury and other emission cont rols in place, will impact CCB management practices.

Laboratory tasks were designe d to address three primary pot ential release mechanisms for mercury over the life cycle of CCBs in a variet y of management scenarios. These release

mechanisms are:

1. Direct leachability of air t oxic constituents from CCBs.

2. Vapor release of mercury from CCBs at ambient and elevated temperatures.

3. Biologically mediated leachability and vapor release of mercury and other air toxic

elements from CCBs.

This report focuses on the methods deve lopment for and results generated from microbiologically mediated experiments to measur e rerelease of mercury from CCBs. This report includes a summary of the methods developmen t over the course of this project and the

associated results. It also summarizes the variou s technical issues associ ated with performing the release experiments and the analys es of the mercury released in both the vapor an d liquid phases. A preliminary interpretation of the results generate d is also included, but fi nal data analysis and interpretation will be included in the final report for the ongoing project entitled “Mercury and Air Toxic Element Impacts of Coal Combustion By-Product Disposal and Utilization” Under which this work was performed.2 BACKGROUND

A majority of mercury emission controls cu rrently being developed and demonstrated in the United States are expected to result in reapportioning of mercur y that was previously released to the atmosphere into CCBs. Research on CCBs has not previously focused on mercury, primarily because the levels of mercury were low and difficult to quantitate, but the potential for significantly increased levels of mercury to be present on CCBs, especially fly ash and FGD, has raised the question of its potential to be rere leased from the CCBs under standard management scenarios. This question should have been addressed prior to implementing mercury emission controls at coal-fired power plants because rerelease or emission from the CCBs could potentially negate the use of the mercury emission controls. Pr eliminary work in the area of direct leaching and direct vapo r-phase rerelease of mercury fr om CCBs indicated that these releases were expected to be very low (1–5). Ho wever, the investigation of the microbiologically mediated rerelease of mercury from CCBs had onl y been initiated on a preliminary level when this project was developed (2–4). Since the chemis try of mercury is unique in that it can form extremely toxic organomercury compounds when e xposed to a variety of microorganisms, the rerelease of mercury from CCBs exposed to mi crobes, including filament ous fungi, is of great

interest both from the fundamental chemis try standpoint and from the CCB management standpoint.

There is a wide distribution and variety of microorganisms in the environment that can promote the rerelease of mercury from many sources including CCBs, and many of these microorganisms have been found to be present in CCB disposal sites and cer tainly are present in environments where CCBs may be used such as in combination with soils for various use applications. A wide variety of specific microbe in teractions can affect key elements associated with CCBs, including oxidation/re duction and alkylation/dealkyla tion reactions. Additionally, in

order for microbes to be metaboli cally active, a few constraints mu st be satisfie d. These include a food source, water, and an appropriate pH. For some CCBs and in some CCB management scenarios, these criteria are un likely to be met, but for scen arios where they can be met, laboratory experiments can be used to simulate appropriate scenarios. Designing these experiments is a challenge as reported previously by the EERC (2–4, 6). The experiments needed to address a variety of materials and take into consideration the microbi ological processes that are expected to allow mercury to be rereleased from CCBs.

Microbiological processes that can aff ect mercury associated with CCBs are:

• Methylation–demethylation type reacti ons involving sulfate-reducing bacteria.

• Formation of:

– Methylmercuric chloride.

– Dimethyl mercury.

– Ethylmercuric chloride.

– Diethyl mercury.

– Many possible others.3 OBJECTIVES

The overall goal of the project under whic h this work was accomplished is to support continued environmentally responsible management of CCBs and appropria te federal regulation of CCBs. Results will provide an indication of appropriate utilization guidelines and disposal requirements. If the environmental performan ce of CCBs from conventional and advanced emission control systems is similar, it will facil itate the maintenance of current CCB markets and minimize the potential for an additional barrier to utilization of CCBs. If the environmental performance changes, the proposed project w ill facilitate an understanding of appropriate management options and provide direction for any future re gulatory assessment of CCBs. Supporting objectives of the project are to 1) determine the release potential of sele cted air toxic elements, including mercury and other air toxic elements, from CCBs under specific environmental conditions; 2) incr ease the database of informati on on mercury and other air toxic element releases for CCBs; 3) develop compara tive laboratory and field data; and 4) develop appropriate laboratory and field protocols.

The objective of this report is to provide information on the methods development for and results of experiments to evalua te the microbiologically mediated rerelease of mercury, arsenic, cadmium, chromium, lead, nickel, and selenium from CCBs. Primary work was accomplished on release of mercury.

METHODS

Early work at the EERC resulted in devel opment of a preliminary method to determine vapor-phase rerelease of mercury from CCBs under microbiologically mediated conditions. Development of the method took into considera tion the properties of CCBs, the chemistry of mercury, and the microbiological processes th at could occur under CCB disposal or land application. The methodology, developed at the EERC, required the CCB or CCB–soil mixture to be buffered to near neutral with phosphate buffer. The sample was dosed with glucose as a carbon and energy source and salts to stimulate micr obial growth and inoculated with a source of microbes. The inoculated sample is sparged w ith mercury-free gas (either air or argon) and

monitored for the release of elements from the mixture.

In the EERC review of published data on the release of mercury from CCBs (1), it was reported that the method developed by the EE RC was the only published method developed and demonstrated for use in evaluating the release of mercury from CCBs on exposure to natural

biota. The EERC method has been under deve lopment since approximately 1999 and has undergone numerous modifications to achieve the goal of evaluating the mercury release potential by leaching and offgassing when CCBs are under microbiol ogically mediated conditions. The first experiments performed usi ng early versions of th e apparatus focused on mercury releases by offgassing. Over the durati on of this project, it was decided that the apparatus and experiments could also be used to determine if microbiologically mediated leaching of mercury was occurring, and measurement of organomercury compounds and air toxic elements in leachate was included as pa rt of the methods development and analysis.4 Description of Initial Apparatus and Method

The first apparatus assembled to conduct micr obiologically mediated vapor-phase mercury release used a 250-mL Erlenmeyer flask fitted with an impinger inlet/outle t tube with the inlet center shortened to 6 cm below the standard tape r. Cylinder gas was passed through several sets of gold-coated quartz traps for mercury removal and admitted to each of the flasks through a gas distribution manifold that routed the gas th rough 0.25-mm gas chromatography (GC) capillary tubing to each of the individual flasks. A GC capillary length of approximately 60 cm, when pressurized to between 1 and 2 psig through a gas distribution manifol d, provided a convenient means of regulating gas flow to approximately 2 cm 3 /min. The gas passed mercury vapor from the head space of the flasks to a mercury vapor collection system at the outlet of the flasks, consisting of two traps. A gold-coated quartz trap (for collection of elemental mercury) and a Supelco CarbotrapTM (for collecti on of organomercury compounds) were used to collect mercury released in the vapor phase from the flasks.

The flasks were placed on a 16-flask wris t action shaker. The experimental matrix consisted of eight flasks under an aerobic conditions (using argon) and eight flasks under aerobic conditions (using breathing-quality air). In each se t of eight flasks, two contained only buffer,

three contained the CCB with buffer (starved), a nd three contained the CCB with buffer and glucose (fed). A 50-gram aliquot of CCB was pl aced in the flasks, and ~100 mL of a phosphate buffer (with or without glucose, as appropriate) was added to create a neutral pH. The CCBcontaining flasks also had 100 μL of mixed bacterial culture added. The source of bacteria was a

mixed bacterial inoculum from a brackish wetl and. This setup is illu strated in Figure 1.

Figure 1. Early microbiologically mediated mercur y vapor-phase collection apparatus utilizing a wrist action shaker to facilitate mixing.5 Modifications of the Apparatus and Experimental Design

The apparatus as described underwent several iterations as difficulties were identified and solutions developed. The wrist-act ion shaker was abandoned, as it was inadequate to suspend the sample during the experiments. Instead of the wrist action shaker, samples were placed in Erlenmeyer flasks on a 9-place st ir plate. This was operated fo r about 20 minutes every 3 hours to maintain sample agitation over the 30-day e xperiment period. Additionally, the sample size was reduced to 20 grams and th e buffer increased to 135–150 mL to provide adequate sample volume for additional trace element analyses. The buffer composition was also altered. It was found that phosphate and nitrate interfered with a derivitization step in the determination of organomercury compounds in the solid-phase microextraction (SPME) process using gas chromatographic separation followed by dete ction of the mercury compounds by atomic fluorescence. This technique is described later. The original buffer utilized nominal concentrations of phosphate a nd nitrate salts. The improved buffer used only 100 ppm of phosphate and substituted potassium glutamate as the nitrogen source. This simple change appeared to remove the interfer ences. Additionally, later experime nts did not involve the use of starved control samples. In current experiment s, all samples are fed with glucose. Table 1

summarizes the modifications and indicates the e xperimental difficulties that the modifications were employed to correct or improve. The final e xperimental apparatus used for the majority of the project microbiologi cal experiments is illustrated in Figure 2.

CCB Preparation Methods

Some CCBs, especially fly ash, can be alkaline in nature. CCB alkalinity can be attributedto the dissolution of alkaline metal oxides that react with water to generate net alkalinity. Watersoluble calcium content contributes most of a CCB’s net alkalinity. This trend can be seen in the classification of fly ashes; Class C fly ash is enriched in Ca a nd Mg and subsequently generates pH values considerably higher th an Class F fly ash (e.g., pH >10).

Table 1. Microbiological Rerelea se Apparatus Modifications Original Experiment or Apparatus Component Difficulty or Unmet Need Modified Experiment or Apparatus Component Wrist Action Shaker, Continuous Shaking Inadequate suspension of sample. Magnetic stir plate, intermittent stirring. 50–80-gram Sample Size +

~100-mL Buffer Inadequate volume of liquid to recover for leachate analysis. ~20 gram sample + 135–

150 mL buffer. Phosphate Nitrate Buffer Solution Inte rference with the determination of the organomercury compounds in

leachate. Lower concentration of phosphate with potassium glutamate as nitrogen

source. Glucose-Fed and Starved Experiments Starved experiments did not promote microbial growth so were deemed

unnecessary. All experiments fed with glucose.

Gold-Coated Quartz Trap Was Followed by Carbotrap at Gas Exit (only in Experiment 1) Organomercury was trapped on the gold-coated quartz so organomercury

could note be measured. Carbotrap was followed by gold-coated quartz trap at gas exit.6 Figure 2. Current microbiologically mediated merc ury vapor-phase collection apparatus utilizing a stir plate to facilitate mixing.

In order for a CCB, or any material, to suppor t biological activity, it mu st be near neutral pH. Microbiological activity of su lfate-reducing bacteria is viable only in the pH range of 6.5 to 8.5, requiring substantial neutraliz ation of some CCBs. Prior to in itiation of experiments, the buffer for that experiment was added to indivi dual samples, pH of the ash–buffer mixture was measured, and an appropriate volume of acid was added over a period of time to achieve a neutral pH.

Microbiological Innoculum Growth Conditions and Media

Since the microbes that promote the release of mercury are ubiquit ous, freshly collected

sediment from a local brackish wetland was used as the innoculum. This innoculum contained a variety of microbes including both aerobic and anaerobic bacteria a nd, therefore, was identified as an appropriate innoculum. The source of the innoculum was the same for all experiments.

The innoculum was prepared by using 1 gram of sediment taken approximately 2 mm from the surface of the sample so th at is was more likely that a high concentration of anaerobic organisms would be present. This sample was added to 10 mL of 0.9 % NaCl and vortexed. This suspension was then used to inoculate the CCB slurry samples.

Experimental Incubation Conditions

Samples were allowed to incubate in sealed flasks at room temperature for 4 weeks. Experiments were all performed in triplicate. Table 2 provides information on the incubation conditions for microbiological rerelease expe riments performed under this project.7Table 2. ExperimentalIncubation ConditionsExperimentNumber ofSamples Runin TriplicateApparatusUsed Acid Addition BufferAsh-to-BufferRatio Incubation ConditionsExperiment 1 1 OriginalapparatusPhosphate/nitrate buffer 50 g to 94 mL Anaerobic and aerobic bothwith glucose-fed andstarved conditionsExperiment 2 1 OriginalapparatusPhosphate/nitrate buffer 50 g to 100 mL Anaerobic and aerobic bothwith glucose-fed andstarved conditionsExperiment 3 1 OriginalapparatusPhosphoric acidadded to neutralizesolution pH toallow microbialgrowthPhosphate/nitrate buffer 80 g to 100 mL Anaerobic and aerobic bothwith glucose-fed andstarved conditionsExperiment 4 3 ModifiedapparatusSulfuric acid added toneutralize solutionpH to allowmicrobial growthPhosphate/glutamic acidbuffer20 g to 150 mL Anaerobic and aerobic withglucose-fed conditionsExperiment 5 3 ModifiedapparatusSulfuric acid added toneutralize solutionpH to allowmicrobial growth forfly ash samplesPhosphate/glutamic acidbuffer20 g to 150 mL Anaerobic and aerobic withglucose-fed conditions; nobacterial innoculum forflue gas desulfurization(FGD) sampleExperiment 6 4 ModifiedapparatusSulfuric acid added toneutralize solutionpH to allowmicrobial growthPhosphate/glutamic acidbuffer18 g to 135 mL Anaerobic and aerobic withglucose-fed conditions8 Mercury Analyses

The mercury collected in the traps designed to collect mercury released in the vapor phase was quantitated at the conclusion of each expe riment. The gold-coated quartz collection traps were desorbed for analysis by heating to approx imately 500°C, and the mass of mercury released was determined using atomic fluorescence (AF) yielding a result indicating the elemental mercury vapor-phase release. The Carbotrap TM collection traps were an alyzed for total mercury by heating the trap to approximately 300°C, pa ssing the released organomercury through a tube at about 800°C, and collecting the mercury vapor on a gold-coated quartz trap, which was analyzed as described above. The result from this analysis was reported as vapor-phase organomercury released.

The leachate was separated from the sample in order to determine the concentrations of mercury in solution. Total mercury concentrati ons of the leachate were determined using CVAFS (cold-vapor atomic florescence spectroscopy).

In order to determine organomercury specie s of the mercury present in the leachates, SPME was used. SPME is a sample collection technique utilizing a fiber coated with polydimethylsiloxane. Samples containing orga nomercury compounds are first derivatized to increase the volatility of or ganomercury halides such as methylmercuric chloride. The derivitization reagents used were sodium tetraethyl borate, sodium tetrapropyl borate, and sodium tetraphenyl borate. Sodium tetraet hyl borate was most commonly used. In the derivitization procedur e, derivatizing agent, acetate buffer, an internal standard (usually propyl mercuric chloride), and sample were mixed in a septum-capped vial. In a relatively fast reaction, the halide is replaced with the appropriate alkyl or aryl group, dependi ng on which derivatizing agent is chosen. A SPME fiber was inserted through the septum cap, and the sample was stirred using a Teflon-coated stir bar for 20 minutes. Af ter this equilibration time, the SPME fiber was

introduced into the heated inlet zone of a GC . Sample separation can be accomplished using a 0.53-mm capillary column 15 or 30 meters in le ngth. The exit end of the column was connected to a heated quartz tube (800°C), and makeup helium gas was added to increase the total flow to between 25 and 30 mL per minute. The gas was then routed to an AF detector for determination of the separated mercury compounds.

Five mL of the liquid plus an aliquot of ethylme rcuric chloride as an internal standard was placed into a 15-mL septum-capped nonactinic vial containing a Teflon-coated stir bar. 500 μL of a pH 4.5 acetate buffer was added followe d by 200 μL of a 1% solution of sodium tetrapropylborate. SPME sampling was accomp lished using a 100-μm polydimethylsiloxanecoated fiber and sampler from Supelco (Bellefonte, Pennsylvania). The head space was sampled

for 20 minutes after which the SPME fiber was directly introduced into the GC.

Microbiological Analysis

Bacterial counts were performed upon completi on of the experiments to determine if there were adequate active microbes present at the co mpletion of the experiment to account for any mercury releases found. A 1-mL aliquot of solution was taken from each flask. The aqueous supernate was serially diluted in 0.1% sodium pyrophosphate buffer (pH 7) and then used to9 inoculate a series of tubes contai ning 1% PTYG (peptone, tryptone, yeast extract, glucose) broth. The tubes were incubated at 25°C, and growth, as turbidity, was monitore d over a 3-week period.

Of the 18 samples, half were grown under an aerobic conditions and the other half were grown under aerobic conditions. Ash samples were removed from the shaker table and a 1-mL aliquot was removed for further processing.

Prior to processing, the ash sample was stored in a flask at 4°C. When processing, 100 μL was removed and added to 9.9 mL sodium pyr ophosphate (PP) buffer ( 0.1% w/v) pH 7.0 with three glass beads in each test tube. This was vorte xed for 30 s then serially diluted into PP buffer (up to 1/1000 dilution). These dilutions were us ed to inoculate a 3-tube most probable number (MPN) assay with 1% peptone–t ryptone–yeast extract–glucose (P TYG) buffer. 4 mL of PTYG were placed in each 13 × 100-mm tube along with innoculum and incubated at room temperature. Tubes and plates (peptone–yeast extract–glucose [PYG] agar) inoculated with samples from the anaerobic ash suspension were incubated under anaerobic conditions (anaerobic hood), and aerobic ash suspension sa mples were exposed to atmospheric oxygen. At week intervals, they were scored based on turbidity.

RESULTS AND DISCUSSION

A variety of CCB samples were evaluated for microbiologically mediated mercury releases using the methods described. The results of experiments are presented for each experiment so the

results can be discussed relative to the methods modifications that were required over the course of the project. Samples included primarily coal combustion fly ash. A complete summary of the samples evaluated and identifying inform ation is included in Appendix A.

Microbiologically Mediated Release of Mercury from CCBs – Experiment 1

The first microbiologically mediated mercur y release experiment was performed on one CCB buffered to near neutral with a phosphate–nitrat e buffer. The CCB tested in Experiment 1 is listed in Table 3. The sample was dosed with gluc ose as a carbon and energy source and salts to stimulate microbial growth and inoculated with a source of microbes. The inoculated sample was sparged with mercury-free gas and monitored fo r the release of mercury from the mixture. Mercury vapor-phase releases only we re quantitated from Experiment 1.

The results from the experiment using Sample 99-188, a subbituminous fly ash neutralized prior to the experiment, are show n in Table 4. AF instrument problems resulted in incomplete results for the elemental mercury captured on some of the gold-coated quartz traps because of the

Table 3. CCB Sample Description and Total Mercury Content, Experiment 1

Sample Sample Type Coal Type Mercury

Control Additional

Information Total Mercury, μg/g
99-188 Fly ash + FGDSDA Subbituminous No Neutralized 0.13110 Table 4. Results of Microbiologically Releas ed Mercury from Sample 99-188, Experiment 1

Anaerobic Gold Trap Hg,

pg Gold Trap Hg, pg/g/day Carbotrap TM Hg,

pg Carbotrap TM Hg, pg/g/day

Blank 3920 NA a 300 NA

Blank 3980 NA 190 NA

Fed 63,100 43.5 720 0.50

Fed 45,600 b 31.5 b 2320 1.60
Fed 69,200 47.7 4140 c 2.86 c

Starved NT d NT 1830 1.26
Starved 47,700 b 32.9 b 5620 3.88
Starved 66,300 45.7 2070 1.43

Aerobic

Blank 23,700 NA 80 NA

Blank 16,500 NA 60 NA

Fed 31,500 1090 1060 36.5

Fed 61,300 2110 860 29.5

Fed 33,200 1140 1930 66.4

Starved 45,000 1550 660 22.8

Starved 42,200 1460 500 17.3

Starved 44,900 1550 890 30.8

a Not applicable.

b Low value because of analyzing conditions.

c High value because of analyzing conditions.

d Not tested.

unexpected high masses of mercury. The elemental mercury release results appear to be higher

from the anaerobic condition. No tr end is apparent for the organom ercury results. This may be because the order of the gold- coated quartz and Carbotrap TM collection traps was incorrect. The gold-coated quartz traps were placed nearest the flask outlet during the experimentation; therefore, it is believed that some of the or ganomercury was trapped on the gold-coated quartz traps before the gas pa ssed to the Carbotrap TM collection traps. The bact erial count showed more

bacteria in the flasks in which the bacteria we re fed glucose in both the anaerobic and aerobic

conditions.

Microbiologically Mediated Release of Mercury from CCBs – Experiment 2

The second microbiologically mediated me rcury release experiment was performed the same as Experiment 1, using Sample 01-002, described in Table 5.11 Table 5. CCB Sample Description and Total Mercury Content, Experiment 2

Sample Sample Type Coal Type Mercury

Control Total Mercury, μg/g
01-002 Fly ash Eastern bituminous No 0.234

The results from th e experiment using Sample 01-002, an eastern bitumi nous fly ash, are

shown in Table 6. The blank fl asks, containing only buffer, yielded higher mercury release values than those containing the CCB slurry. Th e mercury release results show that more elemental mercury was released from flasks in wh ich the bacteria were fed with glucose versus

starved. These values are much lower than t hose from Sample 99-188, pg/ g/day versus ng/g/day.

The bacterial count results show th at the bacteria were able to survive in the aerobic environment and that within the aerobic environment, the bacterial count was higher at the end of the experiment in the flasks where the bacteria were fed with glucose.

Microbiologically Mediated Release of Mercury from CCBs – Experiment 3

The third microbiologically mediated mercury release experiment wa s performed similarly to Experiments 1 and 2. However, phosphoric aci d was added to the flasks to neutralize the slurry pH. The sample tested is shown in Table 7.

Table 6. Results of Microbiologically Releas ed Mercury from Sample 01-002, Experiment 2

Anaerobic Gold Trap Hg, pg Gold Trap Hg, pg/g/day Carbotrap TM Hg,

pg Carbotrap TM Hg, pg/g/day

Blank 1280 NAa 95.47 NA

Blank 2303 NA 203 NA

Fed 155 0.0968 13.45 0.00840

Fed 177.3 0.111 14.12 0.00882

Fed 376.9 0.236 12.66 0.00791

Starved 66.49 0.0415 13.16 0.00822

Starved 45 d 0.0281 22.29 0.0139

Starved 56.28 0.0352 19.9 0.0124

Aerobic

Blank 1096 NA 36.16 NA

Blank 1160 NA 44.52 NA

Fed 405.71 0.253 13.76 0.00860

Fed 1758 1.10 52 d 0.0325

Fed 136.1 0.0851 13.16 0.00822

Starved 48 d 0.0300 5.876 0.00367

Starved 79.39 0.0496 13.59 0.00849

Starved 30.48 0.0190 4.739 0.0029612 Table 7. CCB Sample Description and Total Mercury Content, Experiment 3
Sample Sample Type Coal Type Mercury Control Total Mercury, μg/g
03-060 Fly ash Subbituminous Yes 1.86

Results from CCB 03-060, a subbituminous fly as h collected during a mercury control test,

are shown in Table 8. These resu lts show that elemental mercury is being released from the CCB-containing flasks in the aerob ic environment in which the ba cteria are fed with glucose. The mass of mercury released from the blank flas ks in the aerobic environment was much lower

than in the anaerobic environment.

The results of Experiments 1–3 (Tables 4, 6, and 8) showed some general trends. The mercury released from the CCB slurry was genera lly higher in the samples fed with glucose versus starved samples and in aerobic versus anaerobic conditions. The bacterial count followed a similar trend. The flasks containing buffer only were used as blanks.

Microbiologically Mediated Release of Mercury and Air Toxic Elements from CCBs – Experiment 4

Three samples (see Table 9) were evalua ted under aerobic and an aerobic glucose-fed conditions in triplicate. A 20-gram sample, 150- mL buffer solution, a sample-dependent amount of sulfuric acid, and a 100-μL aliquot of a sulfate-reducing b acteria culture were used for

evaluation. The bacteria were adde d 4 days after the addition of the buffer and acid to allow the systems to neutralize. The system was stirred intermittently over the duration of the experiment. Vapor-phase organomercury releas ed from the system was capture d in tubes containing Supelco CarbotrapTM, and elemental mercury releases were captured on gold-coated quartz traps.

Three days after the bacteria was introduced to the e xperimental vessels, Sample 03-082

under anaerobic conditions exhibited notable change s. The CCB changed from a cream to a gray color, and a hydrogen sulfide smell was emanating from the flasks. The gas from these flasks was directed to flasks containing zinc acetate to capture the hydrogen sulfide being produced.

Table 8. Results of Microbiologically Mediate d Release of Vapor-Phase Mercury and Total Bacterial Counts for Sample 03-060, Experiment 3

Anaerobic Aerobic

Condition Elemental Mercury, pg/g/day Organomercury, pg/g/day Condition Elemental Mercury, pg/g/day Organomercury, pg/g/day

Fed 0.069 0.008 Fed 1.7 0.010

Fed 0.092 0.007 Fed 0.65 0.018

Fed 0.033 0.002 Fed 1.3 0.007

Starved 0.025 0.001 Starved 0.024 0.003

Starved 0.021 0.001 Starved 0.020 0.002

Starved 0.049 0.002 Starved 0.038 0.00213 Table 9. CCB Sample Description and Total Mercury Content, Experiment 4 ID No. Sample Type Coal Type Mercury Control Total Mercury, μg/g 03-079 Fly ash Lignite No 0.785

03-082 FGD

filtercake Eastern

bituminous No 0.218

04-043 Fly ash Lignite No 0.689

Fifteen days after the addition of bacteria, crys tal-like formations were noted on the liquid surface layer from Sample 04-043, two flasks unde r anaerobic and one under aerobic conditions.

In this experiment, 3 weeks elapsed before the addition of the buffer solution; therefore, the gold-coated quartz traps were analyzed to determin e the amount of initial elemental mercury released from the samples in the interim pe riod (see Table 10). Sample and blank flasks generally released similarly low quantities of mercury, but Sample 03-082 under aerobic conditions released significantly more elemental mercury than the other samples. This wet FGD sample was determined to contain a significant population of sulfate-re ducing bacteria. The now mercury-free gold-coated quartz traps were th en replaced on the flasks for collection of elemental mercury over the dur ation of the experiment.

Upon completion of the experiment, eval uations included pH, Eh, elemental and organomercury vapor releases, solution orga nomercury content, and solution elemental

concentrations.

A description of the contents of each samp le flask upon completion of the experiment is included in Table 11. After the liq uid was filtered from the solid, the pH and Eh values were determined. For Samples 03-079 and 03-082, the pH was higher under anaerobic conditions than aerobic; the opposite was true for Sample 04-043. A greater amount of mold was noted in the Sample 04-043 aerobic flasks th at yielded a higher pH.

Table 10. Initial Elemental Mercury Release, pg/g/day, Experiment 4

Anaerobic Aerobic

ID No. Initial Elemental ID No. Initial Elemental

03-079 0.0534 03-079 0.0732

03-079 0.0417 03-079 0.0622

03-079 0.0358 03-079 0.0204

03-082 0.264 03-082 9.20

03-082 0.0341 03-082 9.29

03-082 0.178 03-082 9.83

04-043 0.0454 04-043 0.0313

04-043 0.0245 04-043 0.0356

04-043 0.0358 04-043 0.0588

a One flask broke; therefore, only two samples were evaluated.14 Table 11. Results Including Eh, pH, and Endi ng Sample Description, Experiment 4

Anaerobic Aerobic

ID No. Eh, mV pH Sample Description ID No. Eh, mV pH Sample Description 03-079 164 8.23 Black layer on top of clear liquid; liquid bubbles;

brown ash 03-079 374 8.09 Very slightly brown liquid; black and brown coatings on flask; dark

brown ash 03-079 179 8.30 Black layer on top of clear liquid; liquid bubbles;

brown ash 03-079 314 8.02 Film on top of liquid; very slightly brown liquid; black and brown coatings on flask; dark

brown ash 03-079 189 8.45 Black layer on top of clear liquid; liquid bubbles;

brown ash 03-079 354 7.97 Two spots of mold; film on top of liquid; very slightly brown liquid; black and brown coatings on flask; dark

brown ash

03-082

! 176 8.39 Gray liquid and ash; H 2 S smell;

crusted bubbles on

top of liquid— round on top and

broken on bottom 03-082 a a a

03-082

! 161 8.55 Gray liquid and ash; H 2 S smell; slightly crusted bubbles on top of liquid 03-082 39 7.89 Slightly gray liquid with gold crust on top; smelled like baby formula; gray ash

03-082

! 146 8.51 Gray liquid and ash; H 2 S smell; slimy on top of liquid 03-082 44 7.92 Slightly yellow liquid; smelled like baby formula; gray ash

04-043 164 6.85 Some carbon particles on top of

clear liquid; no noticeable smell; grayish-brown ash 04-043 354 7.61 Layer of mold on top of slightly gray liquid confirmed by smell; grayish-brown ash

04-043 154 6.95 Some carbon particles on top of

clear liquid; no noticeable smell; grayish-brown ash 04-043 279 7.15 No mold smell; grayish liquid; carbon granules on top of liquid; grayish-brown ash

04-043 149 6.81 Some carbon particles on top of

clear liquid; no noticeable smell; grayish-brown ash 04-043 134 7.36 Patch of mold on top ofgray liquid; grayishbrown ash

a One flask broke; therefore, on ly two samples were evaluated.15 The results from th e three samples evaluated under th e modified met hod are shown in Table 12 and reported as picogram s of mercury per grams of CCB. In some instances, the results were highly variable for the replicate flas ks. The highest release of both elemental and organomercury was from Sample 03-082 under aer obic conditions. Analysis of the gold-coated quartz traps from Sample 03-082 under anaerobic conditions resulted in a white, sulfur-smelling deposit on the gold trap. Analyzing the Carbotra pTM tubes from Sample 03-082 aerobic condition

caused a sulfur smell to be released with no deposit formed. Analyzing the CarbotrapTM tubes from Sample 03-082 anaerobic condition resulted in a noticeable sulfur-smelling smoke to be released, and a subsequent fo rmation of a white- to yellow -colored deposit on both the CarbotrapTM and pyrolysis tube. The amount of vapor-phase elemental mercury released coincided with the amount of mold present in the Sample 04-043 aerobic flasks at the completion of the experiment.

SPME was used to determine organomercur y compounds in the liquid remaining in the flasks after the experi mental collection period. Results are shown in Table 13.

Solution elemental concentrations are shown in Table 14.

Microbiologically Mediated Release of Mercury and Air Toxic Elements from CCBs – Experiment 5

Three samples (Table 15) were evaluated in aerobic and an aerobic glucose-fed conditions in triplicate. A 20-g sample, a 150-mL buffer solu tion, a sample-dependent amount of sulfuric acid, and a 100-μL aliquot of a su lfate-reducing bacteria culture were used for evaluation. The experimental systems were brought to a neutral pH by addition of the buffer solution and sulfuric

acid. The bacteria were added afte r neutral pH conditions were f ound to be stable. The remainder of the protocol and setup were the same as in Experiment 4 for Samples 04-035 and 04-036. Samples 04-035 and 04-036 were a paired sample set, collected before and during mercury emission control testing, resp ectively. Sample 03-082, a moist FGD sample evaluated in

Table 12. Vapor-Phase Mercury Release Results, Experiment 4

Anaerobic Aerobic

ID No. Elemental Mercury, pg/g Organomercury, pg/g ID No. Elemental Mercury, pg/g Organomercury, pg/g

03-079 4.1 5.7 03-079 14.7 9.1

03-079 2.8 5.0 03-079 11.3 30.8

03-079 5.3 6.7 03-079 19.8 2.5

03-082 12.7 41.3 03-082 a a

03-082 0.7 2.6 03-082 486 90.0

03-082 1.5 102 03-082 648 110

04-043 1.3 1.1 04-043 46.5 4.5

04-043 2.2 0.6 04-043 4.0 1.4

04-043 1.9 1.0 04-043 9.1 1.3

a One flask broke; therefore, on ly two samples were evaluated.16 Table 13. Solution Organomercury Results, Experiment 4

Anaerobic Aerobic

ID No. Methylmercury Measured,

pg/mL Methylmercury Released, pg/g/day ID No. Methylmercury Measured,

pg/mL Methylmercury Released, pg/g/day

03-079 13 2.65 03-079 32 6.67

03-079 15 3.05 03-079 7 1.47

03-079 <5 <1 03-079 12 2.50

03-082 a a 03-082 b b

03-082 250 50.7 03-082 18 3.75

03-082 a a 03-082 99 20.6

04-043 31 6.30 04-043 <5 <1

04-043 19 3.86 04-043 65 13.6

04-043 18 3.65 04-043 13 2.72

a Samples precipitated colloidal sulfur on standing and were not analyzed.

b One flask broke; therefore, only two samples were evaluated.

Table 14. Leached Total Trace Element Results, μg/L, Experiment 4

Anaerobic Aerobic ID No. As Cd Cr Pb Hg Ni Se ID No. As Cd Cr Pb Hg Ni Se

03-079 99 15 10 <2.0 0.15 350 200 03-079 76 16 2.0 <2.0 <0.01 24 48

03-079 95 15 9.6 <2.0 <0.01 330 200 03-079 49 17 <2.0 <2.0 0.095 36 37

03-079 87 16 8.8 <2.0 <0.01 320 190 03-079 56 17 2.0 <2.0 <0.01 27 14

03-082 12 <0.2 7.7 <2.0 a 25 16 03-082 b b b b b b b

03-082 14 <0.2 20 <2.0 a 25 9.9 03-082 17 <0.2 37 <2.0 0.024 33 17

03-082 11 <0.2 6.8 <2.0 a 27 8.5 03-082 28 <0.2 11 <2.0 0.070 31 20

04-043 12 5.5 8.0 <2.0 <0.01 260 79 04-043 140 5.9 7.1 <2.0 0.020 140 190

04-043 11 5.2 7.8 <2.0 <0.01 250 79 04-043 90 4.2 3.8 <2.0 4.9 130 170

04-043 11 4.7 7.7 <2.0 <0.01 250 78 04-043 71 3.4 3.8 <2.0 0.013 100 210

a Samples precipitated colloidal sulfur on standing and were not analyzed.

b One flask broke; therefore, only two samples were evaluated.

Table 15. Samples Included in Microbiological Release Experiment 5 ID No. Sample Type Coal Type Mercury Control Total Hg, μg/g

03-082 FGD filtercake Eastern bituminous No 0.218 04-035 Fly ash Lignite No 0.160 04-036 Fly ash Lignite Yes 0.287

Experiment 4, required minor revisions to the protocol. The amount of sample was increased from 20 to 22 g to account for the moisture presen t, and no acid or bacteria were added to this sample. Sulfate-reducing bacteria were found to be pres ent in the sample as received, and this experiment was designed to take advantage of th ese natural conditions to serve as a comparison to the experiment run previously under the standard protocol.17 Upon completion of the experiment, eval uations included pH, Eh, elemental and organomercury vapor releases, solution mercur y and trace element concentrations, and a

bacterial count.

Vapor-phase elemental and organomercury re leases were determined using the method

described earlier.

Sample 03-082 under anaerobic conditions change d from a cream color to gray and began to release hydrogen sulfide within 5 days of buffer addition. As noted previously, this sample

was not inoculated and had no acid addition. In the previous experiment, this sample was inoculated 4 days after buffer and acid additi on, with hydrogen sulfide release 3 days after inoculation. Therefore, it appear s that the pH of Sample 03-082 with the buffer addition and the natural bacteria in the sample is sufficient to produce hydrogen sulfide.

The results for Experiment 5 are shown in Tables 16–19. A summary of microbiological

results for the anaerobic and aerobic experiments is noted in Figure 3.

Table 16. Microbiological Eh and pH Results, Experiment 5

Anaerobic Aerobic

ID No. Eh, mV pH ID No. Eh, mV pH

03-082

− 10 8.52 03-082 92 7.81

03-082

− 94 8.52 03-082 81 7.83

03-082 105 8.41 03-082 86 7.83

04-035

− 11 11.26 04-035 12 10.56

04-035

− 21 11.17 04-035 10 10.39

04-035

− 13 11.20 04-035

− 10 10.53

04-036

− 8 11.29 04-036

− 25 10.74

04-036

− 14 11.14 04-036

− 3 10.68

04-036

− 12 11.25 04-036

− 18 10.53

Table 17. Vapor-Phase Mercury Release Results, pg/g/day, Experiment 5

Anaerobic Aerobic ID No. Elemental Mercury Organomercury ID No. Elemental Mercury Organomercury

03-082 NT* NT 03-082 4.64 0.935

03-082 1.54 NT 03-082 9.69 1.62

03-082 NT NT 03-082 8.98 1.01

04-035 0.0279 0.0364 04-035 0.190 0.113

04-035 0.0366 0.0251 04-035 0.150 0.0876

04-035 0.0317 0.135 04-035 0.202 0.0153

04-036 0.0352 0.0242 04-036 0.449 0.0482

04-036 0.147 0.0815 04-036 0.265 0.111

04-036 0.516 0.139 04-036 0.374 0.0723

* Not tested.18 Table 18. Microbiological Leached Total Trace Element Results, μg/L

Anaerobic Aerobic ID No. As Cd Cr Pb Hg Ni Se ID No. As Cd Cr Pb Hg Ni Se

03-082 56 0.36 15 <2.0 0.034 22 23 03-082 14 0.35 13 <2.0 0.018 28 26

03-082 7.9 0.32 14 <2.0 0.041 16 3.8 03-082 19 0.35 15 <2.0 0.014 39 34

03-082 96 0.31 16 <2.0 0.036 18 22 03-082 26 0.34 13 <2.0 0.037 22 30

04-035 NT* NT NT NT NT NT NT 04-035 NT NT NT NT NT NT NT

04-036 NT NT NT NT NT NT NT 04-036 NT NT NT NT NT NT NT

* Not tested.

Table 19. Microbiological Buffer To tal Trace Element Results, μg/L Element As Cd Cr Pb Hg Ni Se

Concentration <2.0 0.41 18 <2.0 <0.01 <2.0 <2.0

Anaerobic Samples 04-035 and 04-036 exhibited no growth in either the broth or plates. Sample 03-082 did show growth in PTYG broth. A bright ye llow color to the media in the test tubes indicated the presence of sulfur-reducing bact eria, especially one flask of Sample 03-082. Cell density was not determined in this sample, and the plates for this sample’s dilution exhibited no growth.

Aerobic Samples 04-035 and 04-036 exhibited no gr owth on either broth or plates. Sample 03-082 plate counts indicated cell density in excess of 25 million cells per mL in the original sample. When the MPN was performe d on the dilution samples in PTYG broth, they indicated cell densities in ag reement with the plate counts.

Figure 3. Summary of mic robiological results.

It is likely that for the samples (04-035 and 04-036) that did not exhi bit growth, it was due largely to pH fluctuations occurring during the fly ash slurry portion of the experiment. Results of leachate mercury and air toxi c element concentrations are found in Table 18. The leachate from Samples 04-035 and 04-036 was not tested because of the excessive pH levels. The microbiological buffer was tested for the same el ements (Table 19). Mercury mobilization can be correlated with growth of microorganisms.

Microbiologically Mediated Release of Mercury from CCBs – Experiment 6

A sixth experiment was initiated to evalua te four samples (Table 20) under aerobic and anaerobic glucose-fed conditions in triplicate. The latest method was modified slightly. An 18-g (instead of 20-g) sample, a 135-mL (instead of 150-mL) buffer solution, and a 100-μL aliquot of a sulfate-reducing bacteria culture were used fo r evaluation. The sample a nd buffer aliquots were19 Table 20. Samples Included in Microbiological Release Experiment 6 ID No. Coal Type Sample Type Mercury Control Total Hg, μg/g 04-035 Lignite Fly ash No 0.160 04-036 Lignite Fly ash Yes 0.287 05-001 Lignite Fly ash No 0.004 05-003 Lignite Fly ash Yes 0.565

reduced to allow for more sulfuric acid, but the ratio of sample to buffer solution was maintained. A sample-dependent amount of sulfur ic acid was added over an extended period of time instead of within 1 day. The bacteria were added after the addition of the buffer and acid to allow the systems to neutralize. The system wa s stirred intermittently over the duration of the experiment.

The samples evaluated consisted of two pair ed sample sets, collected before and during mercury control testing. Samples 04-035 and 04-036 were repeated from the previous experiment because the pH had risen above the accep table pH range for bacterial survival by the end of the previous experiment.

Acid addition over an extended period was attempted to maintain an acceptable pH level

over the duration of the last 30-day experiment. However, th e pH of an aerobic sample measured 10.5 at the 20-day mark, which was significa ntly above the acceptable range of 6.5–8.5 for bacterial survival. The pH of all samples exceeded 10.5, which killed the bacteria. A pH adjustment of all samples was attempted for rei noculation of bacteria but was unsuccessful, and this experiment was aborted because the sample s could not be pH-adjusted to an appropriate range to support microbial activity.

OBSERVATIONS AND CONCLUSIONS

As noted throughout this report, the laborat ory development of the method used and its application to a variety of samples offered significant challenges. Major challenges were:

• High blank values from the buffer solutions.

• Generation of hydrogen sulfide from high-sulfur samples, resulting in poisoning of the analytical traps.

• Difficulty in maintaining a neutral pH, and associated microbial growth, in samples with an initially high pH.

• Growth of fungi in addition to bacterial growth in some samples.

• Difficulty in maintaining constant gas flow to a large number of sample containers, which was solved by use of GC capillary tubing.

• Difficulty in keeping samples suspended.

Several general conclusions can be drawn from the work presented in this report.20 The formation of organomercury compounds wa s evident in all of the microbiologically mediated experiments. Unexpectedly, the greate st releases were found under aerobic conditions. This has been tentatively relate d to fungal action but has not ye t been verified. It has been observed, however, that organomercury formation a ppears to be directly re lated to the amount of fungi present in the flasks at the end of th e experiments. It had been expected that sulfate-reducing bacteria, known to be present in our innoculum and in FGD material samples, would be the primary source of methylation.

Sulfate-reducing bacteria in su lfur-rich samples such as FGD material tended to form large amounts of hydrogen sulfide in th e anaerobic flasks. This hydr ogen sulfide production required putting traps on the flasks in order to keep the hydrogen sulfide and its odor out of the lab. The hydrogen sulfide also made analyses impossible becau se of the formation of colloidal sulfur soon after the samples were harves ted. Additionally, hydrogen sulfide collected in the CarbotrapTM tubes, came off as elemental sulfur and precluded analyses of these traps in our normal manner. This analytical problem is under investigation, but no solu tion has yet been developed.

A further modification to our protocol wi ll involve using a dist illation step in the determination of organomercury in aqueous samples. This will eliminate matrix effects in the derivitization step used just prior to analys is by gas chromatography.

Highly alkaline ash samples generated from li gnite have proven part icularly difficult to maintain at near neutrality. Experiments performed in the absence of bacteria provide us with a neutralization capacity for acid a ddition, but in microbiological e xperiments, thes e neutralized solutions quickly rise to above pH 10.5, thus kill ing the bacteria. We have been using dilute

sulfuric acid for neutralization and believe that afte r neutralization, a sulfate coating has deposited around individual particles. After bacteria are introduced, we believe that the bacterial action may be removing the protective sulfate co ating from alkaline particles thus releasing additional alkalinity. At this time , this is our only working hypothesis and solutions based on this hypothesis are under investigation.

REFERENCES

1. Energy & Environmental Research Center. Me rcury Information Clearinghouse. Quarter 4 – Rerelease of Mercury from Coal Combustion By-Products, Oct 2004.

2. Laudal, D.L.; Hassett, D.J.; Heebink, L.V.; Galla gher, J.R. Stability of Mercury in Coal Combustion By-Products. 2001 Annual Report of the Center for Air Toxic Metals ; organized and administered through the University of North Dakota Energy & Environmental Research Center, for U.S. Environmental Protection Agency Cont ract No. R 827649-01; 2001; pp 51–60.

3. Hassett, D.J.; Heebink, L.V.; Gallagher, J. R.; Pflughoeft-Hassett, D.F.; Laudal, D.L. Stability of Mercury in Coal Combustion By-Products and Sorbents. 2002 Annual Report of the Center for Air Toxic Metals ; organized and administered th rough the University of North21 Dakota Energy & Environmental Research Ce nter, for U.S. Environmental Protection Agency Contract No. R 827649-01; 2002; pp 69–76.

4. Hassett, D.J.; Heebink, L.V.; Gallagher, J.R. ; Laudal, D.L.; Pflughoeft-Hassett, D.F. Stability of Mercury in Coal Combustion By-Products and Sorbents. 2003 Annual Report of the Center for Air Toxic Metals ; organized and administered th rough the University of North Dakota Energy & Environmental Research Ce nter, for U.S. Environmental Protection Agency Contract No. R 827649-01; 2003; pp 103–115.

5. Heebink, L.V.; Hassett, D.J.; Release of Mercury Vapor from Coal Combustion Ash. J. Air Waste Manage

. 2002

, 52 (8), 927–930.

6. Heebink, L.V.; Pflughoeft-Hassett, D.F.; Hassett, D.J.; Zacher, E.J.; Eylands, K.E. Mercury and Air Toxic Element Impacts of Coal Com bustion By-Product Dispos al and Utilization. 2004 Annual Report of the Center for Air Toxic Metals ; organized and administered through the University of North Dakota Energy & E nvironmental Research Center, for U.S. Environmental Protection Agency Contract No. R 827649-01; 2004; pp 115–131.

# APPENDIX A

MICROBIOLOGICAL SAMPLE SETA-1pH = pH too low.IS = Insufficient sample.LP/SOW = Low priority, analysis was not part of the proposed statement of work.LP/ID = Low priority, insufficient sample identification information.NA = Not applicable.ID No. Sample Type Coal Type Hg Control Hg (μg/g) pH LOI Hg Total TotalTrace SGLP 30-day LTL 60-day LTL Thermal Curve Long-Term Ambient Microbiological Carbon Forms99-188 Fly ash + FGD–SDA Subbituminous No 0.112 12.34 2.07% Completed Completed Completed Completed Completed Underway Completed Completed LP/SOW01-002 Fly ash Eastern bituminous No 0.187 4.03 6.05% CompletedCompleted Completed LP/SOW03-060 Fly ash Subbituminous Yes 1.86 11.32 2.28% Completed Completed Completed Completed Completed Underway Completed Completed Completed03-079 Fly ash Lignite No 0.785 11.72 2.54% Completed Completed Completed Completed Completed Underway IS Completed Completed03-082 FGD filtercake Eastern bituminous No 0.218 7.47 4.20% Completed Completed Completed Completed Completed Pending Underway Completed NA04-035 Fly ash Lignite No 0.159 12.68 2.24% Completed Completed Completed Completed Completed Completed UnderwayPending LP/SOW04-036 Fly ash Lignite Yes 0.287 12.64 2.16% Completed Completed Completed Completed Completed Completed UnderwayPending LP/SOW04-043 Fly ash Lignite No 0.689 11.48 Pending Completed Pending Pending Pending Pending Pending IS Completed LP/SOW05-001 Fly ash Lignite No < 0.005 12.84 0.90% Completed Completed UnderwayPending Pending UnderwayPending Pending LP/SOW05-003 Fly ash Lignite Yes 0.565 12.85 1.04% Completed Completed UnderwayPending Pending UnderwayPending Pending LP/SOW

# APPENDIX S

MICROBIOLOGICALLY MEDIATED LEACHING

AND VAPOR-PHASE TRANSPORT TASK

SAMPLE SETID No. Sample Type Hg Control Configuration Coal Type Hg (μg/g)10–15-MinpH, Avg. 24-Hr pHAvg. LOI,%99-188 FGD-SDA PRB Subbituminous 0.112 12.38 12.22 2.07%01-002 Fly Ash Eastern Bituminous 0.187 3.90 NT 6.05%03-006 Fly Ash Eastern Bituminous 0.194 4.71 6.78 5.24%03-007 Fly Ash Eastern Bituminous 0.141 4.27 5.52 4.48%03-060 Fly Ash + Activated Carbon Pre-Primary PCD PRB Subbituminous 1.86 11.32 11.90 2.37%03-079 Fly Ash Fort Union Lignite 0.785 11.77 11.62 2.54%03-082 FGD Filtercake Eastern Bituminous 0.233 7.83 7.85 4.86%04-003 Fly Ash Eastern Bituminous 0.685 9.35 8.54 8.45%04-035 Fly Ash Fort Union Lignite 0.159 12.73 12.74 2.46%04-036Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI Pre-Primary PCD Fort Union Lignite 0.287 12.72 12.77 2.33%04-043 Fly Ash Gulf Coast Lignite 0.689 11.65 11.28 NT05-001 Fly Ash Fort Union Lignite <0.01 12.67 12.51 0.90%05-003Fly Ash + Enhancing Agent +Activated CarbonEnhancing Agent on Coal,ACI before SDA Fort Union Lignite 0.565 12.62 12.29 1.04%05-018 Fly Ash Eastern Bituminous 0.123 7.49 8.49 3.01%Page 1 of 1

# APPENDIX T

FIELD INVESTIGATIONS TASK SAMPLE SET

AND FUNDAMENTAL CHARACTERIZATION

DATAID No. Field Task Sample Type Notes Hg (μg/g) 10–15-Min pH Overnight pH 24-Hr pH Moisture Content, % LOI, %04-055 1 Fly ash <0.01 9.36 9.13 15.0% 5.73%04-056 1 Wet FGD material + mill rejects 0.188 8.62 8.51 21.3% 3.31%04-057 1 Wet FGD material + mill rejects 0.207 8.68 8.53 19.3% 2.18%04-058 1Background Soil from NaturalGrasslands 0.050 8.57 8.40 12.6% 6.88%04-059 1Bottom ash/mill rejects + wetFGD material 0.044 8.77 9.29 7.02% 1.99%04-060 1 Wet FGD material 0.299 8.55 8.27 23.3% 2.49%04-061 1Bottom ash/mill rejects + wetFGD material <0.01 9.08 9.72 16.2% 12.9%04-062 1Bottom ash/mill rejects + wetFGD material <0.01 9.78 10.33 28.8% 7.73%04-063 1Stabilized wet FGD material (withfly ash) 0.080 8.94 9.14 15.0% 3.40%04-064 1Stabilized wet FGD material (withfly ash) 0.250 8.72 8.63 23.5% 2.68%04-065 1Stabilized wet FGD material (withfly ash) 0.011 10.33 10.81 10.1% 3.68%06-014 2 soil-peat moss mix 0.067 7.42 7.48 38.5% 44.2%Page 1 of 1

# APPENDIX U

ALTERNATE FIELD TASK DATATable U-3. CCB–Soil Experiment Organomercury Results Compared to SoilID No. Replicate PeriodCalculatedCCB–SoilMixture HgTotal (μg/g)No.Days inTestingPeriodOrganoHgRelease Rate inTesting PeriodCompared toSoil (pg/g/day)% OrganoHgReleased OverTesting Period (FromCalculated Total Hg)Compared to SoilYears to Release100% CalculatedCCB–Soil MixtureHg at MeasuredRate Compared toSoilAbove orBelow SoilReleaseover TestingPeriodExperimentDuration,DaysCumulativeOrganoHgRelease Rate inTesting PeriodCompared toSoil (pg/g/day)Cumulative %OrganoHg ReleasedOver Testing Period(From Calculated TotalHg) Compared to SoilYears to Release100% CalculatedCCB–Soil MixtureHg at MeasuredRate Compared toSoilAbove orBelow SoilRelease overExperiment03-060 1 1 0.426 19 -0.0047 -0.000021% -249,006 Below03-060 1 2 0.426 22 -0.0008 -0.000004% -1,437,004 Below03-060 1 3 0.426 49 -0.0190 -0.000219% -61,439 Below03-060 1 4 0.426 77 -0.0005 -0.000009% -2,263,313 Below167 -0.0063 -0.000248% -184,590 Below03-060 2 1 0.425 19 -0.0038 -0.000017% -306,627 Below03-060 2 2 0.425 22 -0.0007 -0.000004% -1,675,948 Below03-060 2 3 0.425 49 -0.0200 -0.000230% -58,307 Below03-060 2 4 0.425 77 -0.0008 -0.000015% -1,422,466 Below167 -0.0066 -0.000261% -175,583 Below04-003 1 1 0.190 19 -0.0038 -0.000038% -136,582 Below04-003 1 2 0.190 22 -0.0001 -0.000001% -4,499,912 Below04-003 1 3 0.190 49 -0.0095 -0.000243% -55,157 Below04-003 1 4 0.190 78 0.0393 0.00161% 13,273Above 168 0.0151 0.00134% 34,465Above04-003 2 1 0.190 19 -0.0037 -0.000037% -142,075 Below04-003 2 2 0.190 22 0.0003 0.000004% 1,665,484Above04-003 2 3 0.190 49 0.0006 0.000015% 923,520Above04-003 2 4 0.190 79 0.0239 0.000990% 21,857Above 169 0.0110 0.000977% 47,396Above04-029 1 1 0.106 15 0.0003 0.000005% 884,116Above04-029 1 2 0.106 25 -0.0002 -0.000006% -1,232,013 Below04-029 1 3 0.106 50 -0.0159 -0.000753% -18,201 Below04-029 1 4 0.106 79 0.0029 0.000215% 100,622Above 169 -0.0033 -0.000531% -87,154 Below04-029 2 1 0.106 15 -0.0004 -0.000006% -720,231 Below04-029 2 2 0.106 26 0.0019 0.000047% 150,686Above04-029 2 3 0.106 49 -0.0160 -0.000744% -18,046 Below04-029 2 4 0.106 79 0.0031 0.000233% 92,817Above 169 -0.0030 -0.000481% -96,166 Below04-054 1 1 3.60 19 -0.0039 -0.000002% -2,551,068 Below04-054 1 2 3.60 22 -0.0001 0.000000% -146,858,672 Below04-054 1 3 3.60 49 -0.0136 -0.000019% -723,001 Below04-054 1 4 3.60 81 0.0037 0.000008% 2,645,740Above 171 -0.0026 -0.000012% -3,804,226 Below04-054 2 1 3.60 19 -0.0043 -0.000002% -2,313,976 Below04-054 2 2 3.60 22 -0.0002 0.000000% -50,784,241 Below04-054 2 3 3.60 49 -0.0147 -0.000020% -671,982 Below04-054 2 4 3.60 81 0.0008 0.000002% 12,857,511Above 171 -0.0044 -0.000021% -2,266,176 Below05-009 1 1 0.060 19 -0.0033 -0.000105% -49,631 Below05-009 1 2 0.060 23 0.0002 0.000008% 811,862Above05-009 1 3 0.060 48 -0.0190 -0.00152% -8,632 Below05-009 1 4 0.060 78 0.0093 0.00121% 17,649Above 168 -0.0015 -0.000418% -110,120 Below05-009 2 1 0.060 19 -0.0033 -0.000105% -49,790 Below05-009 2 2 0.060 23 0.0002 0.000006% 1,001,620Above05-009 2 3 0.060 48 0.0047 0.000376% 34,951Above05-009 2 4 0.060 78 0.0254 0.00331% 6,456Above 168 0.0127 0.00358% 12,858Above05-025 1 1 2.58 19 0.0034 0.000003% 2,060,761Above05-025 1 2 2.58 21 0.0057 0.000005% 1,239,898Above05-025 1 3 2.58 50 -0.0092 -0.000018% -771,837 Below05-025 1 4 2.58 82 0.0125 0.000040% 565,151Above 172 0.0044 0.000030% 1,588,470Above05-025 2 1 2.58 19 -0.0038 -0.000003% -1,843,196 BelowPage 1 of 2ID No. Replicate PeriodCalculatedCCB–SoilMixture HgTotal (μg/g)No.Days inTestingPeriodOrganoHgRelease Rate inTesting PeriodCompared toSoil (pg/g/day)% OrganoHgReleased OverTesting Period (FromCalculated Total Hg)Compared to SoilYears to Release100% CalculatedCCB–Soil MixtureHg at MeasuredRate Compared toSoilAbove orBelow SoilReleaseover TestingPeriodExperimentDuration,DaysCumulativeOrganoHgRelease Rate inTesting PeriodCompared toSoil (pg/g/day)Cumulative %OrganoHg ReleasedOver Testing Period(From Calculated TotalHg) Compared to SoilYears to Release100% CalculatedCCB–Soil MixtureHg at MeasuredRate Compared toSoilAbove orBelow SoilRelease overExperiment05-025 2 2 2.58 21 0.0004 0.000000% 16,069,573Above05-025 2 3 2.58 50 -0.0053 -0.000010% -1,344,485 Below05-025 2 4 2.58 82 0.0004 0.000001% 17,531,901Above 172 -0.0016 -0.000011% -4,332,263 Below05-038 1 1 0.074 15 -0.0022 -0.000044% -92,695 Below05-038 1 2 0.074 25 -0.0002 -0.000005% -1,350,142 Below05-038 1 3 0.074 49 -0.0170 -0.00113% -11,913 Below05-038 1 4 0.074 79 -0.0005 -0.000059% -369,850 Below168 -0.0055 -0.00124% -37,037 Below06-014 1 1 0.067 1506-014 1 2 0.067 2506-014 1 3 0.067 4906-014 1 4 0.067 78167Page 2 of 2