### MEMORANDUM

TO: Ron Jordan, EPA Jezebele Alicea, EPA

FROM: Shelly Schultz, ERG TJ Finseth, ERG

DATE: March 1, 2013

SUBJECT: Evaluation of Emerging Technologies for the Treatment of Flue Gas
Desulfurization Wastewater

ERG is providing technical support to the U.S. Environmental Protection Agency’s Office of Water, Engineering and Analysis Division (E AD) for development of effluent limitations guidelines and standards (ELGs) for the Steam Electric Power Generating Industry. EPA, with the support of ERG, identified and evaluated tec hnologies available for th e treatment of power plant wastewater, specifically flue gas desulfurization (FGD) wastewater, to form the basis for the technology-based effluent limitations included in the proposed revisions to the Steam Electric ELGs. Based on the evaluation of the technologies , EPA selected the following three treatment technologies as technology options fo r the treatment of FGD wastewater:

 Chemical precipitation (including hy droxide and sulfide precipitation);

 Anoxic/anaerobic biological treatment (used for heavy metals removal); and

 Vapor-compression evaporation.

EPA also identified other emerging treatment technol ogies that can be used for the treatment of FGD wastewater; however, most of these emer ging technologies are only being evaluated at bench- or pilot-scale levels. This memorandum identifies five other emerging technologies, describes the processes for treating the FGD wastewater, and presents the data currently available regarding the technologi es’ treatment performance.

1.0 I RON C EMENTATION

The iron cementation process cons ists of contacting a wastewater with an iron powder, which reduces a contaminant to its elemental form (i.e., cementation). Iron cementation has been used since the 1500s to remove many types of contamin ants. The less noble (inert ) iron dissolves (i.e., corrodes or oxidizes) while the more noble cont aminant precipitates from solution (i.e., is reduced). The following equation shows th is cementation reaction with copper:

Fe 0 + Cu 2+  Fe 2+ + Cu 0Memorandum March 1, 2013 Page 2

For FGD Wastewater, iron cementation is bei ng looked at for heavy metal removals. The addition of a source of iron during treatment is showing promise for metals such as arsenic, chromium, cadmium, selenium and many others. Some advantages discovered during initial
studies are that this te chnology is relatively low cost with as sociated pollutant removals and does not require significant additional pretreatment. A disadvantage of this technology is that for the best results, the reacti on retention time may be longer than is practical for high volume systems.

EPRI Study

The Electric Power Research Institute (EPRI) perfo rmed bench and pilot studies at a coal-fired power plant to evaluate the poten tial to utilize iron cementation for selenium removal. Initial bench scale testing using the plant’s FGD wastewater suggest ed iron cementation has the potential to reduce the effluent selenium concentration to less than 50 ug/L while minimizing sludge production. This was achieved by testing variations to pH, re action time, and postcementation pH adjustments.

The conclusions made by the bench-scale study aide d in setting test conditions for the follow-on pilot-scale study to evaluate the iron cementatio n technology under continuous flow conditions at a coal-fired power plant. For this pilot study, EPRI used FGD wastewater that had already undergone hydroxide precipitation an d clarification for in itial desaturation of the wastewater. In the pilot study, as shown in Figur e 1, the metallic iron (as an ir on powder) is oxidized to ferrous iron during the selenium reduction process, which occurred in the Iron Reactor with the addition of sulfuric acid to maintain pH. A clarifier was utilized as an iron sepa rator. The iron recovered in the clarifier was recycled back into the Iron Reactor. The overflow from the clarifier was sent to a pH adjustment tank. In the pH adjustme nt tank, the pH was maintained at 8.5 S.U. by addition of caustic. The pH increase resulted in precipitation of solids that contain the target
metals as well as the iron dissolved in the process upstream in the Iron Reactor. The pH adjustment tank effluent was then sent to a fl occulant mixing tank, where it was mixed with a
diluted flocculant solution. The flocculant aide d coagulation and settling of solids in the process

water. 1 EPRI noted that for a full-scale system, clarif iers could be utilized in series with aeration
and filtration.

Figure 1: Basic Schematic of EPRI Iron Cementation Pilot Study

The pilot-study showed that selenium removal improved as the pH was lowered and reaction time was increased; however, this combination also resulted in higher co sts (i.e., higher iron

1 The report does not describe any solids removal mechanisms used to remove solids from the pH adjustment tank or the flocculation tank, but ERG expects that additional solids removal would be required.Memorandum March 1, 2013 Page 3

consumption) and increased sludge production. The pilot st udy also showed that the effectiveness of removing selenium from th e FGD wastewater using iron cementation is dependent on the species of the selenium pres ent. During the pilot study, the iron cementation system was able to remove greater than 99% of the selenite at each pH tested. In comparison, the system was able to remove 95% of selenate at a pH of 4.5 S.U., but the system was only able to remove 37.4% of the selenate at a pH of 5.5 S.U. EPRI noted that the system also achieved significant removals of mercury, ranging from 84.5 to 97.8 percent. 2

This pilot study showed that the iron cementation technology can remove selenium from FGD wastewater containing el evated selenium levels 3 ; however, like chemical precipitation, the removal of selenite is more easily achieved th an removal of selenate. Ultimately, the study was not able to achieve the target effluent total sele nium concentration of 50 ug/ L; the lowest effluent selenium concentration that the system achie ved was 159 ug/L, while the highest effluent selenium concentration was 2,240 ug/L. Additiona lly, relationships between iron retention time, dissolved iron, and selenium reduction were iden tified to allow further optimization of the process and possibly achieve the target effluent concentrations during future studies [EPRI, 2009].

Texas A&M University Study

In addition to the research conducted by EP RI, researchers at Te xas A&M University demonstrated successful heavy metals removals using an Activated Iron Process (AIP) which
uses what the researchers cal l hybrid zero-valent iron (hZVI). The study confirmed that the technology can simultaneously reduce many heavy metals, including selenium, mercury, arsenic, iron, chromium, copper, and cadmium from FGD wa stewater at relativel y low costs. Based on results from successful bench-scale tests, a pilo t study was implemented at an unidentified power plant located in the Southeastern United States. Th e pilot system consisted of four stainless steel zero-valent iron (ZVI) reactors where the iron cementation occurs followed by post-treatment units including aera tion, clarification, and sand filtration. Figure 2 presen ts a diagram of the set up for the pilot scale test.

The study occurred over approximately five months and consisted of two phases. The first phase (January-April) was set up to tr eat 3.8 L/min (1 gpm), while the second phase (April-May) was set up to treat 7.6 L/min (2 gpm). As shown in Fi gure 2, the pilot study used the effluent from the plant’s FGD pond as the influent to the system. The FGD wastewater had typical characteristics of the 22 coal-fired plants that are operated by the host power company. As the researchers were concerned mostly with the removal of selenium and mercury, each of those contaminants were spiked in the feed water to raise their concentrat ions. In addition, research ers were interested in results from just the initial ZVI reactor (i.e., stage one reaction tank) and from the combination
of all four ZVI reactors. Table 1 shows the average influent and effluent results from the study.

2 Because mercury was not a defined target pollutant for th e study, only a limited set of data were evaluated for mercury. The range of percent removals is based on three measurements.

3 The selenium concentrations of the primary clarifier effl uent entering the pilot study ranged from 6,840 ug/L to 8,350 ug/L for total selenium and 5,620 ug/L to 7,060 ug/L for dissolved selenium.Memorandum March 1, 2013 Page 4

Source: [Huang, 2012a]

Figure 2 Diagram of Hybrid ZVI Treatment System Pilot Study

Table 1. Average Influent and Effluent Concentrations for Hybrid ZVI Treatment System Pilot Study

Contaminant FGD Wastewater Influent (ug/L) One Reactor Effluent (ug/L) Four Reactors Effluent (ug/L)

Selenium (as Selenate) 22,000 (spiked) 8,000 4,000 (< 1000 towards the end of the study) Mercury (total) 1,150 (spiked) 0.05 0.025 (< 0.01 towards the end of the study) Lead (dissolved) 5,000 <1 <1 Cadmium (total) 2,500 10 <1 Copper (dissolved) 5,000 1-3 1

Arsenic (total) 20 <1 <1 Chromium (as

chromate) 5,000 10 2

Nitrate 10,000 NR 100
Source: [Huang, 2012] NR - Not reported in the study.

Over the five-month period of the pilot test, th e average consumption rate was 0.3 kg ZVI per 1

m 3 FGD wastewater treate d (0.0025 lbs ZVI/gal FGD wastewater treated). This consumption rate resulted in a cost of approximately $0.6-1.0 per 1 m 3 ($0.0023-0.0038 per gal) FGD wastewater for just the chemical consumption. Costs associated with sludge generation and disposal were not reported. The pilot study demonstrated that the ZV I process is scalable (i.e., multiple reactors can
be utilized to achieve additional removals or expand treatment capacity) [Huang, 2012].

2.0 R EVERSE O SMOSIS

Reverse osmosis (RO) is a well-established membra ne treatment process used for desalination of
seawater and removal of dissolved materials from industrial wastewater. RO systems uses thin film membranes that are semi-permeable, meani ng they allow water but not dissolved solids to flow through; they are permeable to water, but impermeable to dissolv ed solids. In an ROMemorandum March 1, 2013 Page 5

system, high-pressure pumps are used to apply pr essure to the solution from one side of the semi-permeable membrane to force the wa ter through the membrane, leaving behind the dissolved solids and a portion of the water. The rate that wa ter passes through the membrane depends on the operating pressure, concentration of dissolved materials, and temperature, as well as the permeability of the membrane.

As described above, the RO system separates the feed wastewater into two product streams: the permeate, which is the clean water that has pa ssed through the membrane, and the concentrate, which has been retained (“rejected”) by the memb rane. The percentage of membrane system feed that emerges from the system as permeate (i.e ., the volume of permeate divided by the volume of feed) is known as the water recover y. One of the advantages of a RO system is that it can be used to achieve zero liquid discharge in certain appl ications. One of the disadvantages is that the system requires pretreatment to remove excess total suspended solids (TSS) and organics to prevent scaling and fouling 4

.

RO systems are currently in use at steam electri c power plants, usually to treat boiler make-up water or cooling tower blowdow n wastewaters. For example, the Harry Allen Gas Turbine Combined Cycle power plant, located in Nevada, u tilizes RO as part of a zero liquid discharge system. This system design operates at an overall recovery of gr eater than 95% while discharging a stream of wastewater to evaporation ponds and trucking solids off site (Alexander, 2012).

While RO systems may be compatible for the treatment of boiler make-up water or cooling tower blowdown, they are of limited use for the treatment of FGD wastew ater because of the high chloride levels present in FGD wastewater . These high chloride levels lead to a high osmotic pressure, which limits the effectiveness of a reverse osmosis system. To date, there are no cost-effective ways to reduce the chlorides pr esent in the FGD wastewater, and therefore, reverse osmosis systems are not practical for the treatment of FGD wastewater at most plants. However, a RO system could be evaluated at specif ic plants that have low levels of chlorides in the FGD wastewater (e.g., once-through FGD systems).

Allegheny Energy’s Hatfield’s Ferry Power Plant, located in Pennsylvania, considered RO as a potential treatment option to reduce total disso lved solids (TDS) from their FGD wastewater. However, based on research conducted by the plan t, they did not feel RO was a practical treatment method. Part of their treatment goa ls included volume reduction for a zero liquid discharge system and the RO process would ha ve added increased flow to the remaining treatment processes. Furthermore, the wastewater to be treated contained high levels of organic constituents that would produce scaling and f ouling issues of the membrane causing the technology to be inefficient. No laboratory or fiel d tests were performed as part of this evaluation [Black and Veatch, 2008].

3.0 S ORPTION M EDIA

Sorption media systems adsorb pollutants onto the media’s surface area using physical and chemical reactions. A variety of sorption media t echnologies have been used for water treatment.

4 Fouling occurs when both dissolved and suspended solid s deposit onto a membrane surface and degrade its overall performance, thereby decreasing permeate quality and water recovery percentage.Memorandum March 1, 2013 Page 6

The sorbents are typically designed for the remo val of specific pollutant s; however, they may also remove other pollutants simultaneously. The advantages of sorption media are the ease of installation, efficiency of contaminant rem oval, and effectiveness under various pH and contaminant conditions. Some disadvantages with sorption media are that they are typically single use products that require replacement instead of regeneration. Furthermore, they are subject to fouling that may re quire pretreatment to remove suspended solids and organics.

EPRI Study

EPRI research determined that the most common types of adsorbents are metal-based, single use applications, such as granular ferric oxide (or hydroxide) an d titanium based oxides. The advantages of the adsorption media are that it op erates over a wide pH range and it has relatively few interferences from other contaminants presen t in FGD wastewater. One of the disadvantages of the adsorption media is that it requires pr etreatment to remove excess TSS and bioactive organics to prevent plugging and f ouling of the media [EPRI, 2009].

MAR Systems, Inc. Study

A study by MAR Systems, Inc. examined a proprietary functionalized alumina adsorbent technology for its ability to remove both selenite and selenate. It is a single pass through media in a standard filtration vessel. This proprietary adsorption media was developed from various other proprietary chemistries to form functionali zed sites in the media that will form covalent
bonds with selected soluble metals. As these materi als and reactions are all proprietary, details of the chemistry were not reported in this study. At least three of the chemical components forming
the functionalized sites on the media are known to co mplex with soluble selenium in the selenate and selenite oxyanion forms. The removal is accom plished by the formation of various selenite and selenate complexes such as aluminum sele nite, aluminum selenate, and others. The study observed selenium removal rates from 16% to 50% [Sherwood, 2012].

Siemen’s Industry Technologies

Siemens Industry, Inc. installed two types of full-scale sorbent media systems at the Public Service Company of New Hampshire's Merrimack Station for removal of mercury and arsenic. Siemens provided details of these media to ER G in a conference call held on January 2, 2013. These systems include the SCU Adsorbent and the GFH® Media. The SCU Adsorbent is a single use granular carbonaceous adsorbent media which selectively adsorbs dissolved metal cations, including cadmium (Cd), trival ent chromium (Cr+3) , copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), and zinc (Zn). At the Merrimack Station, the SCU Adsorbent is specifically used for mercury removal. The permitted maximum efflue nt mercury concentration at the Merrimack Station was set at 14 parts per tr illion (ppt), based on the plant’s projected performance (i.e., the technology vendor’s guarantee). Th e plant operates a physical/c hemical precipitation system, including hydroxide and sulfid e precipitation, prior to the sorption media systems. Siemens designed the system based on an influent mercur y concentration entering the media at 100 ppt. According to Siemens personnel, the system ha s been achieving low single digit ppt mercury
levels.

To address the arsenic concerns at the Merrimack Station, Siemens utilized its GFH® Media. The GFH® Media is a granulated ferric hydroxide media that is used primarily for the removalMemorandum March 1, 2013 Page 7

of arsenic, but it also achieves removals of ot her heavy metals. According to Siemens personnel,
the GFH® Media is best suited for arsenic removals from wastewater with low silica
concentrations. Siemens did not disclose arsenic removal rates during the call.

Both media developed by Siemens are single us e media, with no regene ration. Therefore, when the media are spent, which is determined based on effluent sampling re sults, the plant must replace the spent media with new media. The me dia can either be replaced by swapping out the entire vessel or vacuuming out the spent media and replacing with new media. Siemens estimates that the capital costs for a system utilizing both media could range from $200,000 to $2,000,000, depending on the flow rate, influent concentra tions, and system configuration. Specific costs associated with the Merrimack Station are prop rietary; however, Siemens provided some general operation and maintenance (O&M) cost estimate s based on their operations. From April to December 2012, the system processed approximately 10 million gallons of water at a rate of approximately 40 gallon per minute. Based on the replacement frequency observed at Merrimack, the media costs for the SCU Adsorbent is approximately $2 per 1,000 gallons and the GFH® Media is approximately $1 per 1,000 ga llons. There are additional costs associated with these systems, such as O&M labor and anal ytical monitoring/sampling that are not included in these estimates [Peschman, 2013].

Zorbtech Environmental Solutions Testing

Zorbtech Environmental Solutions has perfor med bench- and pilot- scale testing on a nonactivated carbon adsorbent media for mercury removal. The company conducted a bench-scale study on power plant scrubber water (which ERG a ssumes is FGD wastewater, but this is not specifically stated in the articl e). The article describing the stu dy contains limited information regarding the treatment steps used in the study and the effluent concentrations achieved, but the article did indicate that mercury re moval was achieved [Purves, 2013].

4.0 I ON E XCHANGE

Ion exchange systems remove specific constituents from wastewater; therefore, the system can target specific metals to be removed. The ion exchange resin works by substituting one ion for another on a specific resin, which must be replaced or regenera ted when the resin becomes full [AEP, 2010]. While the ion exchange process does not generate a re sidual waste, it does generate a regenerant stream that contains the metals st ripped from the wastewater. Ion exchange can be complicated by other contaminants present in the wastewater, as such, the ion exchange systems require pretreatment to remove excess TSS to prevent scaling and fou ling of the resin. A study by ResinTech, Inc. discusses how trace contaminan t removal in wastewater by ion exchange is highly dependent on the other ions that surround the contaminant [Meyers, 2012].

Conemaugh Generating Station

EPA and ERG conducted a visit at GenOn Energy Northeast Management Company’s Conemaugh Generating Station, which operates an ion exchange system for the treatment of boron in FGD wastewater. Upstream of the i on exchange system, the plant treats the FGD wastewater with a physical/chemi cal precipitation system consis ting of hydroxide precipitation
and clarification. The overflow fr om the clarifier is fed to the ion exchange system. The ion exchange system consists of two parallel trains , each capable of handling 75 percent of the flow.Memorandum March 1, 2013 Page 8

The wastewater is first pumped through pressure sand filters and is then transferred to the ion exchange resin vessels. Each tr ain contains two vessels. As de signed, the vessels operate in series, except when one of the vessels is being regenerated. The system was originally designed for regeneration to occur every six hours; howev er, because of scaling issues, the plant has needed to operate the system such that one of the vessels in each train is always being regenerated. As the regeneration of one vesse l is completed, the other vessel begins its regeneration process.

The plant uses sulfuric acid and caustic soda washes to regenerate the resins. The waste from the regeneration process is transferre d to a precipitation tank where th e plant adds ferric chloride and lime. The plant then feeds the water to a clarif ier where a polymer is added. The plant operates filter presses to create a filter cake with the clarifier underflow; therefore, the ion exchange process at this plant does generate a residual sl udge, which is landfilled. The clarifier overflow and the filtrate from the filter presses are recy cled back to the front of the FGD wastewater treatment system (i.e., influent to the chemical precipitation process) for additional processing. The effluent from the ion exchange vessels is tr ansferred to additional treatment systems prior to discharge.

Plant personnel reported obser ving a roughly 85% reduction in bor on concentrations across the chemical precipitation and ion exchange systems. The plant has measured boron concentrations between 400 and 600 ppm in the purge stream and c oncentrations of 75 ppm in the effluent from the ion exchange system. Roughly 45% of th e boron reduction occurs in the chemical precipitation system with the ion exchange syst em removing approximately 70-75 percent of the
boron that remains in the wastewater followi ng the chemical precip itation step [ERG, 2012].

AEP’s Mountaineer Plant

ERG is also aware of a plant that conducted pi lot testing of an ion exchange system that evaluated the removal of mercury in FGD wastewater. As part of American Electric Power’s (AEP) permitting process for the several of its power plants al ong the Ohio River, the company conducted a pilot study at its Mountaineer Pl ant that evaluated f our mercury removal technologies. One of the four systems evalua ted was an ion exchange resin, referred to as “Technology B.” The ion exchange resin was form ulated to specifically target removal of mercury. The objective of the study was to find a technology that will reduce total mercury concentrations to less than 12 ppt. Table 2 presen ts the influent and effluent concentrations for the ion exchange resin observ ed throughout the pilot study as well as a calculated removal
percentage rate.

As Table 2 indicates, the ion exchange resin t echnology was relatively effective at removing total mercury with an average re moval rate of 88.4 percent; howeve r, researchers concluded that although the resign sufficiently removed dissolved mercury it was not effective at removing particulate-bound or colloidal mercury. Therefore, an additional ultraf iltration unit would be required to achieve the target effluent mercury concentration of 12 ppt [AEP, 2010].Memorandum March 1, 2013 Page 9

Table 2. AEP Pilot Study Ion Exchan ge Total Mercury Removal Results

Sample Date Influent to Ion Exchange (ppt) Ion Exchange Resin Technology Effluent (ppt) Removal Rate 7/23/2008 1,210 451 62.7% 7/30/2008 1,550 652 57.9%

8/6/2008 895 231 74.2% 8/13/2008 1,530 408 73.3%

8/20/2008 612 48.7 92.0%

8/27/2008 851 200 76.5% 9/3/2008 1,940 125 93.6%

9/10/2008 758 45.2 94.0% 9/17/2008 1,990 15.4 99.2% 9/24/2008 1,840 14.1 99.2%

10/1/2008 643 4.8 99.3%

10/8/2008 665 NM NM

10/15/2008 651 NM NM

10/22/2008 437 13.4 96.9%

10/29/2008 205 8.9 95.7%

11/5/2008 282 3.1 98.9%

11/12/2008 505 4.7 99.1%

11/19/2008 224 10.3 95.4%

11/26/2008 342 NM NM

12/3/2008 181 NM NM

12/10/2008 261 12.6 95.2%

Average 836.8 132.2 88.4%

Source: AEP, 2010.
NM: Not Measured

5.0 E LECTRO -C OAGULATION

Electro-coagulation (EC) is a technique utilized in wastewater treatment in which an electrical charge is applied to the water causing a change in particle surface charge, allowing suspended
solids to fall out of solution. These systems typically use alum inum or iron electrodes, which dissolve into the wastestream during the process. Th e dissolved metallic ions precipitate with the other pollutants in the wastewater and form inso luble metal hydroxides. According to EPRI, the pollutants removed by iron coprecip itation in a standard chemi cal precipitation system should also be removed by an electro-coagulation syst em utilizing an iron electrode. One of the advantages of the EC system is that is has the po tential to remove hard-to- treat pollutants such as selenium. Some of the disadvantages of the syst em are that it requires a constant power source and it may increase the wastewater concentrations of the metals forming the electrodes used in the system (e.g., aluminum, iron). Additionally, the EC system requires pretreatment to adjust the pH to between 7.5 and 9.0 S.U.

The Duke Energy Mayo plant at one point considered EC as a possible treatment option for treating its FGD wastewater; however, the plan t has chosen to install a vapor-compression evaporation system [Loewenburg, 2012].Memorandum March 1, 2013 Page 10

University of Florida Study

A University of Florida study for the installati on of a new FGD wastewater system at a power plant in Crystal River, Florida proposed usi ng a combination of EC, ion exchange, and zero liquid discharge. EC was identified as a poten tial treatment option based on bench-scale testing using FGD wastewater from a plant in Roxboro, NC . The bench scale test determined that EC
could be used to remove seleni um from FGD wastewater and that the best setup for EC was two aluminum plates separated with U-shaped rubbe r spaces. In this bench-scale study, filtered FGD wastewater at pH 8 S.U. was pumped through a small Tygon tube using a peristaltic pump into the bottom of the EC, through a hole in the rubber space. The pH of 8 S.U. for the influent water
was chosen because it minimizes the contribution of solids from the elec trodes. The researchers conducted two separate tests using the same FGD wastewater for the tests.

Analytical results from the bench-scale study ar e included in Table 3. Fo r every analyte, two detection wavelengths were used and the table presents the results for the two be nch-scale tests for both wavelengths. The specific wavelengths used for the analyses were not provided in the study report. Calcium and magnesium do not have specific goal discharge limits; however, these pollutants do need to be controlle d in order to meet the total wa ter hardness limit for the plant.

As shown in Table 3, removals of selenium were achieved for both EC samples, for at least one of the wavelengths used for the analyses. However, the EC system increased the aluminum and iron concentrations across the treatment system. The researchers determined that aluminum and
iron could be removed with downstream of the EC system using water softening [University of Florida, 2010.]

Table 3. University of Florida EC Study Results

Analyte Equipment
Detection Limits (ppm) Goal Discharge Limits (ppm) Influent (ppm) EC Treated Sample 1

(ppm) EC Treated Sample 2

(ppm) Ag 0.0009 0.1 0.006 0.006 BDL Ag 0.0009 0.1 0.015 BDL BDL

Al 0.003 1.5 0.071 528.200 533.900

Al 0.003 1.5 BDL 1066.000 1080.000

Ca 0.0002 --- 2179.667 120.700 131.600

Ca 0.0002 --- 2181.000 109.200 117.900

Fe 0.002 0.3 0.014 6.453 6.928

Fe 0.002 0.3 0.012 6.357 6.810 Mg 0.00007 --- 532.667 21.190 23.330 Mg 0.00007 --- 534.333 20.430 22.560

Mn 0.0004 0.1 1.508 25.880 26.520

Mn 0.0004 0.1 1.490 25.720 26.380

Se 0.05 0.071 1.580 0.092 BDL

Se 0.05 0.071 BDL BDL BDL

BDL – Below detection limit.Memorandum March 1, 2013 Page 11

References

1. Alexander, Gerald, et al. 2012. A Unique Integrated Memb rane Makeup and Zero Liquid Discharge System for a Co mbined Cycle Power Plant Siemens Industries, Inc. DCN
SE03961.

2. AEP. 2010. American Electric Power Mercur y Removal Effectiveness Report. (29 January). DCN SE02008.

3. Black and Veatch, 2009. Allegheny Energy Inc. Hatfield’s Ferry Power Stations Conceptual Wastewater Treatment Engin eering Study and Cost Estimate. DCN SE03960.

4. Eastern Research Group, Inc. (ERG). 2013. Final Conemaugh Site Visit Notes. (16 March). DCN SE03756.

5. Electric Power Research Institute (EPRI). 2009b. Selenium Removal by Iron
Cementation from a Coal-Fired Power Plant Flue Gas Desulfurization Wastewater in a Continuous Flow System – Pilot St udy. 1017956. Palo Alto, CA. (July). DCN
SE00409A2.

6. Huang, Yong H, et al. 2012. Field Demonstration of the Activated Iron Technology for Removing Heavy Metals from Flue -Gas-Desulfuriza tion Wastewater, Texas A&M University. DCN SE03966.

7. Loewenburg, Matthais et al. 2012. Zero

‐ Liquid Discharge System at Duke Energy Mayo
Plant . GEA Process Engineering, Inc. DCN SE02027.

8. Meyers, Peter. 2012. Removal of Trace Contaminants by Ion Exchange. ResinTech, Inc.
DCN SE03962.

9. Schultz, Shelly, et al. 2013. Telephone call w ith ERG. “Discussion of Merrimack Station System Operation and Costs.” East ern Research Group, Inc. DCN SE03901.

10. Purves, Bill et al. Cost Effectively Removing Mercury in a Wastewater Streams . Accessed
2013. DCN SE03964.

11. Sherwood, Nancy et al. 2012 . Selenite and Selenate Removal by a Functionalized Alumina Adsorption Technology, MAR Systems, Inc. DCN SE03963.

12. University of Florida, Integrated Product and Process Design Program, 2010. Flue Gas Desulfurization Wastewater Mitigation . DCN SE03973.