United States 

Environmental Protection 

Agency 

AQUABOX 50 and MARABU 

Packed Biological Reactor 

System Technology Evaluation 

Innovative Technology 

Evaluation Report 
June 2000 

AQUABOX 50 AND MARABU PACKED 

BIOLOGICAL REACTOR SYSTEM 

TECHNOLOGY EVALUATION 

INNOVATIVE TECHNOLOGY EVALUATION REPORT

EPA - BMBF BILATERAL SITE 

DEMONSTRATION

STADTWERKE DUESSELDORF AG SITE, 

DUESSELDORF, GERMANY

by

Tetra Tech EM Inc. 

1230 Columbia Street, Suite 1000 

San Diego, California 92101 

Contract No. 68-C5-0037 

Work Assignment Order No. 0-05 

Work Assignment Manager 

Ann Vega 

Land Remediation and Pollution Control Division 

National Risk Management Research Laboratory

 Cincinnati, Ohio 45268 

National Risk Management Research Laboratory

Office of Research and Development 

 U.S. Environmental Protection Agency

 Cincinnati, Ohio 45268 

EPA/540/R-07/003
NOTICE 

The information in this document has been prepared for the U.S. Environmental Protection Agency=s 

(EPA) Superfund Innovative Technology Evaluation program by Tetra Tech EM Inc. under Contract No. 

68-C5-0037. This document has been prepared in accordance with a bilateral agreement between the 

EPA and the Federal Republic of Germany Ministry for Research and Technology. This document has 

been subject to EPA peer and administrative reviews, and has been approved for publication as an EPA 

document. Mention of trade names or commercial products does not constitute an endorsement by the 

EPA or recommendation for use. 

ii 
FOREWORD 

The Superfund Innovative Technology Evaluation (SITE) program was authorized by the Superfund 

Amendments and Reauthorization Act of 1986. The U.S. Environmental Protection Agency (EPA) Office 

of Research and Development established the program to accelerate the development and use of 

innovative remediation technologies applicable to Superfund and other hazardous waste sites. The SITE 

program accomplishes these goals through pilot- or full-scale demonstrations designed to collect 

performance and economic data of known quality on selected technologies. 

This demonstration evaluated the effectiveness of two different biological reactors in treating 

groundwater contaminated with benzene, toluene, ethylbenzene, and xylenes (BTEX), naphthalene, 

acenaphthene, and fluorene. The AQUABOX 50 and MARABU packed biological reactors were 

evaluated at a former manufactured gas (coal gasification) plant that operated from 1890 to 1967 in a 

section of Duesseldorf, Germany known as Duesseldorf-Flingern. The primary industrial process at the 

former manufactured gas plant, the Stadtwerke Duesseldorf AG (SWD) site in Duesseldorf, Germany, 

was the conversion of coal to natural gas; associated by-products of this process include BTEX and 

polycyclic aromatic hydrocarbons (PAH). The facility has been operated by SWD as an operations yard 

from post-1967 to the present. While the manufactured gas plant was in operation, aquifer contamination 

occurred through storage system leaks, improper handling of by-products, and World War II bombing 

damage. Further contamination occurred approximately 25 years ago when the gasworks were 

demolished. This innovative technology evaluation report provides an interpretation of the data collected 

during the demonstration and discusses the potential applicability of the technology to other contaminated 

sites. 

Hugh W. McKinnon, Director 

National Risk Management Research Laboratory 

iii 
 

 

 

 

 

TABLE OF CONTENTS

Section Page 

NOTICE........................................................................................................................................................ii 

FOREWORD ...............................................................................................................................................iii 

EXECUTIVE SUMMARY..................................................................................................................... ES-1 

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

1.1 SUPERFUND INNOVATIVE TECHNOLOGY EVALUATION PROGRAM................ 3 

1.2 UNITED STATES AND GERMAN BILATERAL AGREEMENT ON 

REMEDIATION OF HAZARDOUS WASTE SITES....................................................... 5 

1.3 BIOLOGICAL REACTOR TECHNOLOGY DESCRIPTION ......................................... 6 

1.3.1 Process Equipment................................................................................................ 6 

1.3.2 System Operations ................................................................................................. 9 

1.4 KEY CONTACTS .............................................................................................................. 9

2.0 BIOLOGICAL REACTOR TECHNOLOGY EFFECTIVENESS.................................................... 10 

2.1 BACKGROUND .............................................................................................................. 11 

2.1.1 Site Background................................................................................................... 11 

2.1.2 Demonstration Objectives and Approach ............................................................ 12 

2.2 DEMONSTRATION PROCEDURES ............................................................................. 15 

2.2.1 Evaluation Design................................................................................................ 15 

2.2.2 Sampling and Analysis Program.......................................................................... 16 

2.2.2.1 Sampling and Measurement Locations................................................... 16 

2.2.2.2 Sampling and Analytical Methods.......................................................... 17 

2.2.3 Quality Assurance and Quality Control Program ................................................ 19 

2.2.3.1 Field Quality Control Checks ................................................................. 21 

2.2.3.2 Laboratory Quality Control Checks........................................................ 21 

2.2.3.3 Field and Laboratory Audits................................................................... 21 

2.3 EVALUATION RESULTS AND CONCLUSIONS........................................................ 21 

2.3.1 Operating Conditions........................................................................................... 21 

2.3.1.1 Treatment System Configuration............................................................ 22 

2.3.1.2 Operating Parameters.............................................................................. 22 

2.3.2 Results and Discussion ........................................................................................ 23 

2.3.2.1 Primary Objectives ................................................................................. 23 

2.3.2.2 Secondary Objectives ............................................................................. 26 

2.3.3 Data Quality......................................................................................................... 35


2.3.3.1 Groundwater Samples............................................................................. 35


2.3.3.2 Gas Samples............................................................................................ 36


2.4 CONCLUSIONS .............................................................................................................. 41


3.0 ECONOMIC ANALYSIS.................................................................................................................. 42


4.0 TECHNOLOGY APPLICATIONS ANALYSIS .............................................................................. 44


iv 
 

 

TABLE OF CONTENTS (Continued) 

Section Page 

4.1 FEASIBILITY STUDY EVALUATION CRITERIA...................................................... 45


4.1.1 Overall Protection of Human Health and the Environment................................. 45


4.1.2 Compliance with ARARs .................................................................................... 45


4.1.3 Long-Term Effectiveness and Permanence ......................................................... 46


4.1.4 Reduction of Toxicity, Mobility, or Volume Through Treatment....................... 46


4.1.5 Short-Term Effectiveness .................................................................................... 46


4.1.6 Implementability.................................................................................................. 46


4.1.7 Cost...................................................................................................................... 46


4.1.8 State Acceptance.................................................................................................. 47


4.1.9 Community Acceptance....................................................................................... 47


4.2 APPLICABLE WASTES ................................................................................................. 47


4.3 LIMITATIONS OF THE TECHNOLOGY...................................................................... 47


5.0 BIOLOGICAL REACTOR SYSTEM TECHNOLOGY STATUS................................................... 48


6.0 REFERENCES .................................................................................................................................. 49


v 
1 

2 

3 

4 

5 

6 

FIGURES 

Number Page 

1 SITE LOCATION 2 

2 BILATERAL PROJECT ORGANIZATION 7 

3 TREATMENT SYSTEM SCHEMATIC 8 

4 DATA REDUCTION, VALIDATION, AND REPORTING SCHEME 20 

TABLES 

Number Page 

ANALYTICAL METHODS 19 

RANGE AND MEAN MASS REMOVAL EFFICIENCIES FOR THE TOTAL SYSTEM 24 

SUMMARY OF REMOVAL EFFICIENCY CALCULATIONS FOR THE TOTAL SYSTEM 25 

SUMMARY OF THE INFLUENT FLOW RATES TO THE SYSTEM 25 

RANGE AND MEAN REMOVAL EFFICIENCIES FOR THE SYSTEM COMPONENTS 27 

SUMMARY OF MASS REMOVAL EFFICIENCY CALCULATIONS FOR SYSTEM 

COMPONENTS 28 

7 STRIPPING EFFICIENCIES FOR EACH COMPONENT OF THE TREATMENT SYSTEM 31 

8 RANGE AND MEAN STRIPPING EFFICIENCIES FOR EACH COMPONENT 32 

9 PHYSICAL AND CHEMICAL CHARACTERISTICS OF THE TREATED WATER 33 

10 MATRIX SPIKE/MATRIX SPIKE DUPLICATE RESULTS, EVENT 1 36 

11 MATRIX SPIKE/MATRIX SPIKE DUPLICATE RESULTS, EVENT 2 37 

12 MATRIX SPIKE/MATRIX SPIKE DUPLICATE RESULTS, EVENT 3 37 

13 MATRIX SPIKE/MATRIX SPIKE DUPLICATE RESULTS, EVENT 3 RETEST 38 

14 MATRIX SPIKE/MATRIX SPIKE DUPLICATE RESULTS, EVENT 4 38 

15 GAS MATRIX SPIKE/MATRIX SPIKE DUPLICATE RESULTS, EVENT 1 39 

16 GAS MATRIX SPIKE/MATRIX SPIKE DUPLICATE RESULTS, EVENT 2 39 

17 GAS MATRIX SPIKE/MATRIX SPIKE DUPLICATE RESULTS, EVENT 3 40 

18 GAS MATRIX SPIKE/MATRIX SPIKE DUPLICATE RESULTS, EVENT 4 40 

vi 
ACRONYMS AND ABBREVIATIONS

ASTM American Society for Testing and Materials 

BFB 4-Bromofluorobenzene 

BMBF German Federal Ministry of Education, Science, Research, and Technology 

BS Blank spike 

BSD Blank spike duplicate 

BTEX Benzene, toluene, ethylbenzene, and xylenes 

EC Degrees Celsius 

Ca Calcium 

CCC Calibration check compound 

CERCLA Comprehensive Environmental Response, Compensation, and Liability Act 

Cl- Chloride 

CS2 Carbon disulfide 

DFTPP Decafluorotriphenylphosphine 

DHHS U.S. Department of Health and Human Services 

EPA U.S. Environmental Protection Agency 

F- Fluoride 

Fe Iron 

GC/MS Gas chromatography/mass spectroscopy 

HCl Hydrochloric acid 

ICP Inductively coupled plasma 

ITER Innovative Technology Evaluation Report 

IUM Ingenieurbuero fuer Umwelttechnik und Maschinenbau GmbH 

K Potassium 

L/min Liters per minute 

3 m Meters cubed 

m3

/h Meters cubed per hour 

MCAWW Methods for the Chemical Analysis of Water and Wastes (EPA, 1983) 

MDL Method detection limit 

Mg Magnesium 

Mn Manganese 

vii 
ACRONYMS AND ABBREVIATIONS (Continued) 

MSD Matrix spike duplicate 

Na Sodium 

NBM NBM Petrol Stations & Industry 

NIOSH National Institute of Occupational Safety and Health 

NO3 

- Nitrate 

NO2 

- Nitrite 

NPL National Priorities List 

NRMRL National Risk Management Research Laboratory 

ORD Office of Research and Development 

PAH Polycyclic aromatic hydrocarbons 

PO4 

3­ Phosphate 

PQL Practical Quantitation Limit 

Probiotec ArGe focon-PROBIOTEC 

PVC Polyvinyl chloride 

QA Quality assurance 

QA/QC Quality assurance/quality control 

QAPP Quality assurance project plan 

QC Quality control 

QM-TAP Qualitätsmanagement-Testablaufplan 

%R Percent recovery 

RE Removal efficiency 

RF Response factor 

RPD Relative percent difference 

%RSD Percent relative standard deviation 

SARA Superfund Amendments and Reauthorization Act 

SITE Superfund Innovative Technology Evaluation 

SO4 

2­ Sulfate 

SPCC System performance check compounds 

SWD Stadtwerke Duesseldorf AG 

viii 
ACRONYMS AND ABBREVIATIONS (Continued) 

Tetra Tech Tetra Tech EM Inc. 

UBA Umweltbundesamt 

FG/L Micrograms per liter 

VOA Volatile organic analysis 

VOC Volatile organic compounds 

ix 
CONVERSION TABLE 

(Metric to English Units) 

To Convert Into Multiply By 

Centimeters Feet 0.0328 

Centimeters Inches 0.394 

Cubic meters Cubic feet 35.3 

Cubic meters Gallons 264 

Cubic meters Cubic yards 1.31 

Degrees Celsius Degrees Fahrenheit multiply by 1.80; add 

32 

Kilograms per square meter Pounds per square inch, absolute 0.00142 

Kilograms Pounds 2.20 

Kilograms per liter Pounds per cubic foot 12.8 

Kilometers Miles (statute) 0.622 

Liters Gallons 0.260 

Liters per second Cubic feet (standard) per minute 2.12 

Meters Feet 3.28 

Millimeters Inches 0.0394 

Square meters Square feet 10.8 

x 
ACKNOWLEDGMENTS

This report was prepared under the direction of Dr. Ronald Lewis of the EPA National Risk Management 

Research Laboratory (NRMRL) in Cincinnati, Ohio. This report was prepared by Mr. Roger Argus, Ms. 

Elizabeth Barr, Mr. Steven Geyer, Ms. Linda Hunter, and Dr. Greg Swanson of Tetra Tech EM Inc. Ms. 

Ann Vega of NRMRL, Dr. Jorg Siebert of Probiotec, and Dr. Reiner Kurz of Institut Fresenius were 

contributors to, and reviewers of, this report. 

xi 
EXECUTIVE SUMMARY

This innovative technology evaluation report (ITER) summarizes the results of an evaluation of the 

AQUABOX 50 and MARABU Packed Biological Reactor technologies. The evaluation was conducted 

under a bilateral agreement between the United States (U.S.) Environmental Protection Agency (EPA) 

Superfund Innovative Technology Evaluation (SITE) program and the Federal Republic of Germany 

Ministry for Research and Technology (BMBF). The Stadtwerke Duesseldorf AG biological reactor 

system was demonstrated from July 15, 1999 through August 31, 1999 at the Stadtwerke Duesseldorf AG 

site in Duesseldorf, Germany. 

The Biological Reactor Technology 

Two packed biological reactors, operated concurrently in a side-by-side demonstration, were included in 

the evaluation: the AQUABOX 50 and the MARABU. The purpose was to evaluate the efficiencies of 

each reactive barrier to remove benzene, toluene, ethylbenzene, and xylenes (BTEX) and polycyclic 

aromatic hydrocarbons (PAHs) from the contaminated groundwater plume located at the site. The 

AQUABOX 50 was provided to Stadtwerke Duesseldorf AG (SWD) by NBM Petrol Stations & Industry 

(NBM). The MARABU was designed by SWD with design assistance from Ingenieurbuero fuer 

Umwelttechnik und Maschinenbau GmbH (IUM). The overall treatment system has been operated and 

maintained by SWD since December 1995. 

The AQUABOX 50 and MARABU are designed to treat the influent groundwater through biodegradation 

by microbes that grow on the packed bed media. The AQUABOX 50 bioreactor consists of five 

connected compartments, each 2 cubic meters (m3

) in volume (for a total volume of 10 m3), incorporating 

a packed bed consisting of a polyvinyl chloride (PVC) mat with rough, linear extrusions. The MARABU 

bioreactor consists of one 1.5 m3

 compartment, incorporating a packed bed consisting of polyethylene 

rings. Each bioreactor is supplied with an aeration system to ensure sufficient oxygen for the bacteria. 

These aeration systems employ air flow rates of 4 cubic meters per hour (m3

/hr) fresh air and 50 m3/hr 

circulated air in the AQUABOX 50, and 5 m3

/hr fresh air in the MARABU with no circulated air. 

Groundwater was extracted at varying pumping rates from five recovery wells installed within the 

contaminant plume. Extracted groundwater from four of the recovery wells at a combined flow rate of 

about 20 m3

/hr was pumped into the AQUABOX 50, and extracted groundwater from one recovery well 

at a flow rate of about 3 m3

/hr was pumped into the MARABU. Treated water from both the AQUABOX 

50 and MARABU bioreactors flowed through separate piping into the same intermediate storage tank, 

with a total storage capacity of 20 m3

. This tank was aerated at a flow rate of 7 m3/hr to reduce iron 

ES-1 
concentrations in the treated water by promoting oxidation and precipitation which occurs within the sand 

filter. High iron concentrations are a natural characteristic of the facility groundwater. 

The partially treated water flowed from the storage tank through a 30 m3

 sand filter (10 m3 water capacity) 

to remove residual iron. Trapped bacteria in the sand filter provided further contaminant biodegradation 

in the previously treated groundwater. The groundwater was then passed through an activated carbon 

unit, which filtered out the residual organic contamination prior to infiltration back into the aquifer. 

Exhaust gases from each system component were passed through activated carbon prior to final 

atmospheric discharge. Backup activated carbon units were also in place at each of the three gas exhausts 

and at the sand filter effluent. 

Waste Applicability 

Both the AQUABOX 50 and MARABU bioreactors effectively reduced dissolved-phase BTEX and 

PAHs from the groundwater. 

Demonstration Objectives and Approach 

This bilateral SITE demonstration of the AQUABOX 50 and MARABU packed biological reactor 

systems was designed with two primary and four secondary objectives. The objectives were chosen to 

provide potential users of the technology with the information necessary to assess the applicability of the 

biological reactor technology for treatment of groundwater at other contaminated sites. The following 

primary and secondary objectives were selected to evaluate the technology: 

Primary Objectives 

P1 Demonstrate greater than 95 percent average removal efficiency for total BTEX and greater than 

60 percent average removal efficiency for the three most prevalent PAHs (acenaphthene, 

fluorene, and naphthalene) for the overall system. The overall system includes the AQUABOX 

50, MARABU, and sand filter, but excludes the activated carbon system component. 

P2 Measure the removal efficiencies for BTEX and the three most prevalent PAHs across each of the 

treatment units, including the AQUABOX 50, MARABU, and sand filter. 

ES-2 
Secondary Objectives 

S1 Determine the percent of total BTEX and naphthalene that is stripped from each aerated 

component of the system. 

S2 Document the physical and chemical characteristics of the treated water that could affect the 

performance of the evaluation system and document how these parameters change with 

treatment. 

S3 Document the capital and operating costs of the SWD AQUABOX 50 and MARABU packed 

biological reactor system based on observations during the evaluation and data from the 

engineering designers and from the operator of the system. 

Demonstration Conclusions 

This demonstration was limited to an evaluation of the technology=s ability to remove BTEX and PAHs 

from groundwater. Based on the biological reactor technology demonstration, specific conclusions are 

summarized below. 

C The removal efficiencies for the three target PAHs, acenaphthene, fluorene and napthalene, and 

BTEX for the total system were all greater than 99 percent. These removal efficiencies exceeded 

the target removal efficiencies of 60 percent for the PAHs and 95 percent for the total BTEX. 

C The removal efficiencies for the three target PAHs and the total BTEX were calculated for three 

components of the system, the AQUABOX 50, the MARABU and the sand filter. The removal 

efficiencies of the AQUABOX 50 for acenaphthene, fluorene and napthalene ranged from 70.4 

percent to 99.8 percent, 75.2 percent to 99.2 percent, and 91.0 percent to 99.8 percent, 

respectively. The removal efficiency for total BTEX of the AQUABOX 50 ranged from 92.3 

percent to 97.0 percent. The removal efficiencies of the MARABU for acenapthene, fluorene and 

napthalene ranged from 47.0 percent to 66.1 percent, 53.6 percent to 71.5 percent, and 75.3 

percent to 90.2 percent, respectively. The removal efficiency for total BTEX of the MARABU 

ranged from 67.6 percent to 74.6 percent. The removal efficiencies of the sand filter unit for 

acenaphthene, fluorene and napthalene ranged from 99.0 percent to 99.4 percent, 95.7 percent to 

97.2 percent, and 97.5percent to 98.9 percent, respectively. The removal efficiency for total 

BTEX of the sand filter unit ranged from 28.6 percent to 94.6 percent. 

C The stripping efficiencies (percent of influent mass stripped into the exhaust gas) for the three 

target PAHs and the total BTEX were calculated for the three components of the system. 

Stripping efficiencies of the AQUABOX 50 for acenaphthene, fluorene, and napthalene, ranged 

from <0.01 percent to <0.06 percent, <0.04 percent to <0.1 percent, and <0.02 percent to <0.08 

percent, respectively. Stripping efficiency for total BTEX of the AQUABOX 50 ranged from 0.2 

percent to 1.0 percent. Stripping efficiencies of the MARABU for acenaphthene, fluorene, and 

napthalene, ranged from 0.1percent to 0.2 percent, <0.06 percent to <0.08 percent, and 0.2 

percent to 0.4 percent, respectively. Stripping efficiency for total BTEX of the MARABU ranged 

from 6.9 percent to 8.8 percent. Stripping efficiencies of the sand filter for acenaphthene, 

ES-3 
C

fluorene, and napthalene, ranged from <0.02 percent to <0.06 percent, <0.1 percent to <0.2 

percent, and 0.2 percent to 0.5 percent, respectively. Stripping efficiency for total BTEX of the 

sand filter ranged from 3.2 percent to 28.4 percent. 

The following physical and chemical characteristics of the treated water were measured at the 

four influent wells to the AQUABOX 50, the one influent well to the MARABU, and the effluent 

well from the sand filter: pH, sodium, potassium, calcium, iron, magnesium, manganese, chloride, 

floride, nitrite, nitrate, phosphate, sulfate, bicarbonate (alkalinity), lead, copper, cadmium, zinc, 

nickel, chromium, arsenic, and mercury. The following trends were noted: 

$ Groundwater samples taken from influent sampling well to the AQUABOX 50 

located at WA3 had the highest sodium, potassium, calcium, iron, manganese, 

chloride, floride, sulfate, and zinc concentrations. 

$ Groundwater samples taken from the influent sampling well to the MARABU 

located at WM1 had the lowest sodium, calcium, magnesium, nitrate, phosphate, 

and sulfate concentrations. 

$ Groundwater samples taken from the effluent located at WK had the lowest iron, 

manganese, nitrite, phosphate, and zinc concentrations. All of these analytes had 

been significantly reduced, most likely due to the precipitation reactions 

occurring within the biological reactive boxes. The highest concentration of 

nitrate was recorded in samples taken from the effluent sampling location. 

$ Lead, cadmium, chromium, and mercury concentrations were less than the 

detection limit in all monitoring wells. Copper and nickel concentrations were 

detected in two of the influent wells at low concentrations. Arsenic was detected 

in all monitoring wells at low concentrations. 

$ The initial capital cost of the biological reactor system at the Stadtwerke Duesseldorf AG Site, 

including site preparation, permitting and regulatory costs, construction materials and labor, and 

startup was about 218,700 DM ($113,900 U.S. dollars assuming a 1.92 DM to $1 U.S. dollar 

exchange rate). Monitoring and other periodic costs amounted to about 37,000 DM ($19,300 

U.S.) per year. 

ES-4 
1.0 INTRODUCTION

This report documents the findings of an evaluation of two biological reactors. The AQUABOX 50 

was provided to Stadtwerke Duesseldorf AG (SWD) by NBM Petrol Stations & Industry (NBM). 

The MARABU was designed by SWD with design assistance from Ingenieurbuero fuer 

Umwelttechnik und Maschinenbau GmbH (IUM). The overall treatment system, which incorporates 

of these two biological reactors set up side-by-side and operated concurrently, was operated and 

maintained by SWD at the Stadtwederke Duesseldorf AG site in Duesseldorf, Germany (see Figure 1 

for location). The demonstration period was from July 15 through August 31, 1999. This evaluation 

was conducted under a bilateral agreement between the U.S. Environmental Protection Agency (EPA) 

Superfund Innovative Technology Evaluation (SITE) program and the Federal Republic of Germany 

Ministry for Research and Technology (BMBF). 

The demonstration evaluated each technology=s effectiveness in enhancing the removal of benzene, 

toluene, ethylbenzene, and xylenes (BTEX) and the polycyclic aromatic hydrocarbons (PAHs) 

naphalene, fluorene, and acenaphthene, from contaminated groundwater. The evaluation was carried 

out by Tetra Tech EM Inc. (Tetra Tech), ArGe focon-PROBIOTEC (Probiotec), SWD facility 

personnel, and Institut Fresenius, in accordance with the July 1999 quality assurance project plan 

(QAPP) (Tetra Tech 1999). Groundwater was sampled by Institut Fresenius with assistance from 

Probiotec and Tetra Tech. Probiotec was responsible for ensuring that all sampling, analytical, and 

QA/QC requirements were effectively communicated to Institut Fresenius. Probiotec reviewed the 

sampling and analytical data obtained during the system evaluation for validity and assessed 

measurement systems for precision and accuracy. SWD demonstrated the technology. 

The subject site is currently owned by a public utility company (Stadtwerke Duesseldorf AG). SWD 

was responsible for facilitating access to the site and for supporting the evaluation. SWD also 

operated, maintained, and monitored the treatment system at the site. SWD was responsible for 

coordinating evaluation activities with Probiotec and Institut Fresenius to ensure that all requirements 

are met, and for reporting operational and monitoring data. All samples were analyzed by the Institut 

Fresenius laboratory in Taunusstein. All demonstration activities were conducted in accordance with 

the referenced QAPP. 

1 
 



  

  	 


2
1.1 

Probiotec focon-Probiotec, Stadtwerke Duesseldorf AG facility personnel, and Institut Fresenius 

contributed to the development of this document. 

This report provides information from the bilateral SITE demonstration of the AQUABOX and 

MARABU biological reactor technologies that is useful for remedial managers, environmental 

consultants, and other potential technology users in implementing this technology at contaminated 

sites. Section 1.0 presents an overview of the SITE program and bilateral agreement, describes the 

technology, and lists key contacts. Section 2.0 presents information relevant to the technology=s 

effectiveness, including contaminated aquifer characteristics and site background, demonstration 

procedures, and the results and conclusions of the demonstration. Section 3.0 presents information on 

the costs associated with applying the technology. Section 4.0 presents information relevant to the 

technology=s application, including an assessment of the technology in relation to nine feasibility 

study evaluation criteria used for decision making in the Superfund process. Section 4.0 also 

discusses applicable wastes/contaminants and limitations of the technology. Section 5.0 summarizes 

the technology status, and Section 6.0 lists references used in preparing this report. 

SUPERFUND INNOVATIVE TECHNOLOGY EVALUATION PROGRAM 

This section provides background information about the EPA SITE program. Additional information 

about the SITE program, the AQUABOX 50 and MARABU biological reactor technology, and the 

technology demonstration can be obtained by contacting the key individuals listed in Section 1.4. 

EPA established the SITE program to accelerate the development, demonstration, and use of 

innovative technologies to remediate hazardous waste sites. The demonstration portion of the SITE 

program focuses on technologies in the pilot-scale or full-scale stage of development. The 

demonstrations are intended to collect performance data of known quality. Therefore, sampling and 

analysis procedures are critical. Approved quality assurance and quality control (QA/QC) procedures 

are stringently applied throughout the demonstration. 

Past hazardous waste disposal practices and their human health and environmental impacts prompted 

the U.S. Congress to enact the Comprehensive Environmental Response, Compensation, and Liability 

Act (CERCLA) of 1980 (PL96-510). CERCLA established a Hazardous Substance Response Trust 

Fund (Superfund) to pay for handling emergencies at and cleaning up uncontrolled hazardous waste 

sites. 

3 
Under CERCLA, EPA has investigated these hazardous waste sites and established national priorities 

for site remediation. The ultimate objective of the investigations is to develop plans for permanent, 

long-term site cleanups, although EPA initiates short-term removal actions when necessary. EPA=s 

list of the nation=s top-priority hazardous waste sites that are eligible to receive federal cleanup 

assistance under the Superfund program is known as the National Priorities List (NPL). 

As the Superfund program matured, Congress expressed concern over the use of land-based disposal 

and containment technologies to mitigate problems caused by releases of hazardous substances at 

hazardous waste sites. As a result of this concern, the 1986 reauthorization of CERCLA, called the 

Superfund Amendments and Reauthorization Act (SARA), mandates that EPA Aselect a remedial 

action that is protective of human health and the environment, that is cost effective, and that utilizes 

permanent solutions and alternative treatment technologies or resource recovery technologies to the 

maximum extent practicable.@ In response to this requirement, EPA established the SITE program to 

accelerate development, demonstration, and use of innovative technologies for site cleanups. The 

SITE program has four goals: 

C Identify and remove impediments to development and commercial use of innovative 

technologies, where possible 

C Conduct evaluations of the more promising innovative technologies to establish reliable 

performance and cost information for site characterization and cleanup decision-making 

C Develop procedures and policies that encourage selection of effective innovative 

treatment technologies at uncontrolled hazardous waste sites 

The Demonstration Program is the flagship of the SITE Program. Its objective is to conduct field 

demonstrations and high quality performance verifications of viable remediation technologies at sites 

that pose high risks to human health and/or the environment are common throughout the region or the 

nation, or where existing remediation methods are inadequate, unsafe, or too costly. The SITE 

Program solicits applications annually from those responsible for clean-up operations at hazardous 

waste sites. A panel of SITE Program scientists, engineers, and associated environmental experts 

reviews the applications to identify those technologies that best represent solutions for the most 

pressing environmental problems. The resulting data and reports are intended for use by decisionmakers in selecting remediation options and for increasing credibility in innovative applications. 

4 
1.2 

SITE evaluations are usually conducted at uncontrolled hazardous waste sites, such as EPA removal 

and remedial action sites, sites under the regulatory jurisdiction of other federal agencies, state sites, 

EPA testing and evaluation facilities, sites undergoing private cleanup, the technology developer=s 

site, or privately owned facilities. In the case of the biological reactor technology demonstration, the 

Stadtwerke Duesseldorf AG site was selected cooperatively by EPA and BMBF. 

SITE and bilateral SITE evaluations provide detailed data on the performance, cost effectiveness, and 

reliability of innovative technologies. These data were provided potential users of a technology with 

sufficient information to make sound judgments about the applicability of the technology to a specific 

site or waste and to allow comparisons of the technology to other treatment alternatives. 

UNITED STATES AND GERMAN BILATERAL AGREEMENT ON 

REMEDIATION OF HAZARDOUS WASTE SITES 

In April 1990, EPA and BMBF entered into a bilateral agreement to gain a better understanding of 

each country=s efforts in developing and demonstrating remedial technologies. The bilateral 

agreement has the following three goals: 

C Facilitate an understanding of each country=s approach to remediation of 

contaminated sites 

C Demonstrate innovative remedial technologies as if the demonstrations had taken 

place in each country 

C Facilitate international technology exchange 

Technologies under development in the U.S. and Germany are evaluated under the bilateral 

agreement. Individual, or in some cases, multiple remedial technologies are demonstrated at each 

site. Technology evaluations occurring in the U.S. correspond to SITE evaluations; those occurring 

in Germany correspond to full-scale site remedial activities and are referred to as bilateral SITE 

evaluations. In the case of the U.S. evaluations, demonstration plans are prepared following routine 

SITE procedures. Additional monitoring and evaluation measurements required for evaluation of the 

technology under German regulations were specified by the German partners. For the demonstrations 

occurring in Germany, the German partners were provided all required information to allow the U.S. 

to develop an EPA NRMRL Applied Research QAPP. An EPA NRMRL Applied Research QAPP, 

AQuality Assurance Project Plan for the SWD AQUABOX 50 and MARABU Packed Biological 

5 
Reactor System Technology at the Stadtwerke Duesseldorf AG Site in Duesseldorf, Germany,@ dated 

July 1999, was prepared for this demonstration (Tetra Tech 1999). 

Probiotec (a partnership of two German environmental consulting firms) was commissioned by 

BMBF to compile summary reports for the German technologies and sites, to evaluate the U.S. 

demonstration plans, and to facilitate the bilateral agreement on behalf of BMBF. The Probiotec 

technical consulting partnership is not directly involved in the German remedial actions, and the 

partnership does not influence actual site remediation activities. The bilateral project organization is 

presented in Figure 2. 

1.3 BIOLOGICAL REACTOR TECHNOLOGY DESCRIPTION 

This section describes the process equipment and system operations of the AQUABOX 50 and 

MARABU packed biological reactors. This section also describes the conventional components of 

the overall treatment system technology. 

1.3.1 Process Equipment 

The AQUABOX 50 bioreactor consists of five connected compartments, each 2 cubic meters (m3

) in 

volume (for a total volume of 10 m3

), incorporating a packed bed consisting of a polyvinyl chloride 

(PVC) mat with rough, linear extrusions. The MARABU bioreactor consists of one 1.5m3 

compartment, incorporating a packed bed consisting of polyethylene rings. A schematic of the 

treatment system is shown in Figure 3. 

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8
1.3.2 System Operations 

Groundwater is extracted at varying pump rates from five recovery wells installed within the 

contaminated groundwater plume. Extracted groundwater from four of the recovery wells is pumped 

into the AQUABOX 50 at a combined flow rate of about 20 cubic meters per hour (m3

/h). Extracted 

groundwater from one recovery well is pumped into the MARABU at a flow rate of about 3 m3

/h. 

The AQUABOX 50 and MARABU treat the influent groundwater through biodegradation by 

microbes that grow on the packed bed media. Each bioreactor is supplied with an aeration system to 

ensure sufficient oxygen for the bacteria. These aeration systems employ air flow rates of 4 m3

/h 

fresh air and 50 m3

/h circulated air in the AQUABOX 50, and 5 m3/h fresh air with no circulated air 

in the MARABU. Treated water from both the AQUABOX 50 and MARABU bioreactors flows 

through separate piping into the same intermediate storage tank with a total storage capacity of 20 m3

. 

This tank is aerated at a flow rate of 7 m3

/h which promotes the precipitation of the oxidated iron to 

occur within the sand filter. (The presence of high concentrations of iron in the facility groundwater 

is a natural characteristic of the area.) 

The partially treated water flows from the storage tank through a 30-m3

 sand filter (10 m3 water 

capacity) to remove residual iron. Trapped bacteria in the sand filter provide further contaminant 

biodegradation in the previously treated groundwater. The groundwater then filters through an 

activated carbon unit to remove residual organic contamination prior to infiltration back into the 

aquifer. 

Exhaust gases from each system component are passed through activated carbon prior to final 

atmospheric discharge. Backup activated carbon units are also in place at each of the three gas 

exhausts and at the sand filter effluent. 

1.4 KEY CONTACTS 

Additional information on the biological reactor technology and the EPA-BMBF bilateral technology 

evaluation program can be obtained from the following sources: 

9 
 

Dr. Karlheinz Huebenthal 

Federal Ministry for Research and Technology

Heinemannstrasse 2 

53175 Bonn, Germany

Tel. 49-228-57-3069 

Dr. Annett Weiland-Wascher 

Umweltbundesamt 

Bismarckplatz 1 

14191 Berlin, Germany

Tel. 49-8903-3569 

Biological Reactor Technology 

Dr. Hans-Peter Rohns 

Stadtwerke Duesseldorf 

Abt. Wasserwirtschaft und Technik 

Faerberstrasse 78 

40223 Duesseldorf 

Tel. 49-211-821-8316 

EPA-BMBF Bilateral Technology Evaluation Program 

Annette Gatchett 

Bilateral Program Manager and SITE Program Manager 

U.S. Environmental Protection Agency

Office of Research and Development 

26 West Martin Luther King Drive 

Cincinnati, Ohio 45268 

Tel. 513-569-7697 

Information on the SITE Program is also available through the following on-line information 

clearinghouse: The Vendor Information System for Innovative Treatment Technologies (Hotline: 

(800) 245-4505) database contains information on 154 technologies offered by 97 developers. 

Technical reports may be obtained by contacting U.S. EPA/NCEPI, P.O. Box 42419, Cincinnati, 

Ohio 45242-2419, or by calling (800) 490-9198. 

2.0 BIOLOGICAL REACTOR TECHNOLOGY EFFECTIVENESS 

This section documents the background, field and analytical procedures, results, and conclusions of 

the Stadtwerke Duesseldorf AG bilateral SITE technology evaluation. 

10 
2.1 BACKGROUND 

The bilateral SITE demonstration of the SWD AQUABOX 50 and MARABU Packed Biological 

Reactors was conducted at the Stadtwerke Duesseldorf AG site in Duesseldorf, Germany (Figure 1). 

The site background and an overview of the demonstration objectives and approach are described in 

the following subsections. 

2.1.1 Site Background 

The bilateral SITE demonstration of these technologies was conducted at a facility owned and 

operated by a public utility company, SWD. The facility was operated as a manufactured gas (coal 

gasification) plant from 1890 to 1967. The primary industrial process at manufactured gas plants is 

the conversion of coal to natural gas; associated by-products of this process include BTEX and 

polycyclic aromatic hydrocarbons (PAH). The facility has been operated by SWD as an operations 

yard from post-1967 to the present. While the manufactured gas plant was in operation, aquifer 

contamination occurred through storage system leaks, improper handling of by-products, and World 

War II bombing damage. Further contamination occurred approximately 25 years ago when the 

gasworks were demolished. 

Environmental assessments conducted between 1991 and 1993 identified several dissolved-phase 

hydrocarbon plumes in the facility groundwater. The results of these assessments were used to 

prioritize release areas at the facility in terms of clean-up priority. The top-priority plume (based on 

measured benzene) is located at an area of the facility historically used for benzene production. This 

plume has been chosen as the study area for this technology evaluation. Components of this plume 

include BTEX and PAHs. The contaminant plume is approximately 600 meters long by 100 meters 

wide by 10 to 15 meters in height, the top of which is approximately 6.5 to 7.5 meters below the 

ground surface (bgs) (and 1.5 meters below the water table). Groundwater samples were collected 

and analyzed from within this plume on March 23, 1999 to document current conditions. 

11 
2.1.2 Demonstration Objectives and Approach 

Demonstration objectives were selected to provide potential users of the system with the necessary 

technical information to assess the applicability of the treatment system at other contaminated sites. 

For this bilateral SITE evaluation, two primary objectives and three secondary objectives were 

developed and are summarized below: 

Primary Objectives 

P1 Demonstrate greater than 95 percent average removal efficiency for total BTEX and 

greater than 60 percent average removal efficiency for the three most prevalent PAHs 

(acenaphthene, fluorene, and naphthalene) for the overall system. The overall system 

includes the AQUABOX 50, MARABU, and sand filter, but excludes the activated carbon 

system component. 

To accomplish this objective samples were collected from the influent water wells, labeled WA1 

through WA4 for the AQUABOX 50 reactor, and one water location labeled WM1 for the MARABU 

reactor. Samples were also taken from the effluent water location labeled WK. Samples were 

collected once per week for a total of 4 weeks and analyzed for BTEX and the three most prevalent 

PAHs, acenaphthene, fluorene, and napthalene. Summary results were expressed as a mean and a 

range of removal efficiencies obtained over the 4-week evaluation period, and the mean result was 

compared to the objective. 

To achieve objective P1, a removal efficiency (RE) was calculated on a mass basis for the entire 

system (excluding the pre-infiltration activated carbon filter) for each sampling event using the 

following equation: 

(QCi − QCe) RE = X100

QCi

Where: 

RE = Removal efficiency (%) 

Ci = Calculated contaminant concentration in the influent to the system (a single flowweighted average concentration was calculated based on the measured contaminant 

concentrations in the flow lines from the five influent wells - WA1 through WA4 and 

WM1) 

Ce = Measured concentration in the effluent from the gravel filter (WK) 

12 
Q = Flow rate of groundwater through the system (sum of flows for each of the five 

influent flow lines - WA1 through WA4 and WM1) 

The above equation was applied to data from each sampling event. Four separate REs were 

calculated for the system for each sampling event: total BTEX, acenaphthene, fluorene, and 

naphthalene. 

To achieve objective P2, individual REs were calculated for the AQUABOX 50, MARABU, and sand 

filter using the above equation, with the following variable description substitutions: 

RE

Ci 

= 

= 

Removal efficiency (%) of each of the bioreactors and the sand filter 

Contaminant concentration in the influent to each of the bioreactors and the sand 

filter (a single weighted average concentration was calculated for the AQUABOX 50 

based on the detected contaminant concentrations of the four influent wells - WA1 

through 4; the concentration at WM1 was used for the MARABU; the concentration 

at WZ was used for the sand filter) 

Ce = Contaminant concentration in the effluent from each of the bioreactors (WA5 and 

M2) and the sand filter (WK) 

P2 Measure the removal efficiencies for BTEX and the three most prevalent PAHs across each of 

the treatment units, including the AQUABOX 50, MARABU, and sand filter. 

To accomplish this objective, influent samples were collected from the influent wells as described 

above, with the addition of the sand filter influent sample location (WZ). Effluent samples were 

collected from each of the bioreactor effluents, including the AQUABOX 50 (WA5) and the 

MARABU (WM2) as well as the the sand filter effluent (WK). Samples were collected once per 

week for a total of 4 weeks and analyzed for BTEX and the three most prevalent PAHs, 

acenaphthene, fluorene, and napthalene. Summary results were expressed as a mean and a range of 

removal efficiencies obtained over the 4-week evaluation period, and the mean result was compared 

to the objective. 

To achieve objective P2, individual REs were calculated for the AQUABOX 50, MARABU, and sand 

filter using the above equation under objective P1, with the following variable description 

substitutions: 

RE = Removal efficiency (%) of each of the bioreactors and the sand filter 

Ci = Contaminant concentration in the influent to each of the bioreactors and the sand 

filter (a single weighted average concentration was calculated for the AQUABOX 50 

based on the detected contaminant concentrations of the four influent wells - WA1 

through 4; the concentration at WM1 was used for the MARABU; the concentration 

at WZ was used for the sand filter) 

13 
Ce = Contaminant concentration in the effluent from each of the bioreactors (WA5 and 

WM2) and the sand filter (WK) 

Secondary Objectives 

S1 Determine the percent of total BTEX and naphthalene that is stripped from each aerated 

component of the system. 

To accomplish this objective, individual exhaust gas samples were collected from each of the system 

components at locations before the activated carbon units (GA1, GM1, and GZ1). These exhaust gas 

samples were collected on the same schedule as the influent/effluent water sampling activities (once 

per week for a 4-week period) and analyzed for BTEX and napthalene. Summary results were 

expressed as a mean and a range of the percentage removed by air stripping over the 4-week 

evaluation period. 

To achieve objective S1, the percentage of total BTEX and naphthalene removed by the aeration 

component of the treatment system was calculated using the following equation: 

Qa, eCa, e

SE = 

Qw, iCw, i 

Where: 

SE = Stripping efficiency (%) 

Qa,e = Air flow rate at emission sampling point 

Ca,e = Concentration of contaminant in the air stream at the sampling point 

Qw,i = Groundwater flow rate in the influent to each of the bioreactors and the sand filter 

Cw,i = Contaminant concentration in the influent groundwater 

S2 Document the physical and chemical characteristics of the treated water that could affect the 

performance of the evaluation system and document how these parameters change with 

treatment. 

To accomplish this objective, samples were collected once per week from five influent water 

wells and the effluent water well for the total system during the 4-week sampling period. 

These samples were analyzed for pH; major cations, including sodium (Na), potassium (K), calcium 

(Ca), iron (Fe), magnesium (Mg) and manganese (Mn); and anions, including chloride (Cl-

), fluoride 

(F-

), nitrate (NO3-), nitrite (NO2-), phosphate (PO4

3-), and sulfate (SO42-). 

14 
S3 Document the capital and operating costs of the SWD AQUABOX 50 and MARABU packed 

biological reactor system based on observations during the evaluation and data from the 

engineering designers and from the operator of the system. 

SWD had estimated the capital and operating costs of this system based on operating requirements 

observed during the evaluation and on capital and operating cost information available from the 

designers and operator of the system. To accomplish this objective, the preliminary construction cost 

estimate was updated, and operational costs were also compiled based on data provided by SWD. 

2.2 DEMONSTRATION PROCEDURES 

This section describes the methods and procedures used to collect and analyze samples for the 

bilateral SITE demonstration of the biological reactor system technology. The activities associated 

with the biological reactor technology demonstration included (1) evaluation design, (2) groundwater 

collection and analysis, and (3) field and laboratory QA/QC. Section 2.2.1 presents the evaluation 

design. The methods used to collect and analyze samples are outlined in Section 2.2.2. Field and 

laboratory QA/QC procedures are described in Section 2.2.3. 

2.2.1 Evaluation Design 

The purpose of the evaluation was to collect and analyze data of known and acceptable quality to 

achieve the objectives as described in Section 2.1.2. 

15 
 

 

 

2.2.2 Sampling and Analysis Program 

The main objective of the sampling and analysis program is to provide sufficient data to allow EPA to 

evaluate the performance of the SWD AQUABOX 50 and MARABU packed biological reactor 

treatment system through meeting the primary and secondary evaluation objectives discussed in 

Section 2.1.2. Because of logistical constraints and the schedule requirements of the German bilateral 

partners, the evaluation of this system was limited to a time period of 4 weeks during July, 1999. 

Thus, samples that are representative of long-term operation cannot be practically obtained. 

Therefore, the goal of the planned sampling procedures was to obtain a sufficient number of samples 

to be representative of this short evaluation period and to maximize the representativeness of these 

samples so that the results accurately reflect the performance of the treatment system during the 

evaluation period. 

2.2.2.1 Sampling and Measurement Locations 

Sampling locations selected based on the configuration of the treatment system and project objectives 

are shown in Figure 3. 

• WA1: Influent water from recovery well 19059 into AQUABOX 50 (flow rate of ~5 m3

/h) 

• WA2: Influent water from recovery well 19124 into AQUABOX 50 (flow rate of ~3 m3

/h) 

• WA3: Influent water from recovery well 19123 into AQUABOX 50 (flow rate of ~3 m3

/h) 

• WA4: Influent water from recovery well 19071 into AQUABOX 50 (flow rate of ~9 m3

/h) 

• WM1: Influent water from recovery well 19125 into MARABU (flow rate of ~ 3 m3

/h) 

• WA5: Effluent water from AQUABOX 50 

• WM2: Effluent water from MARABU 

• WZ: Effluent water from intermediate storage tank/influent to sand filter 

•	 WK: Effluent water from sand filter; total system (except carbon) effluent sampling 

location 

• GA1: Exhaust gas stream from AQUABOX 50 

• GM1: Exhaust gas stream from MARABU 

• GZ1: Exhaust gas stream from intermediate storage tank 

16 
2.2.2.2 Sampling and Analytical Methods 

This section described procedures for collecting representative samples at each sampling location and 

analyzing collected samples. Grab sampling techniques were employed throughout the 

demonstration. Samples were collected at nine locations. 

System operating parameters were monitored continuously by facility personnel. Sampling began 

after facility personnel judged that the system was operating at a steady state. 

Groundwater Samples 

Influent and effluent water samples were collected from the treatment system once per week for a 

total of 4 weeks. The effluent water samples were collected after the influent, to account for the 

retention time in the system in order to obtain a representative sample. Water samples were collected 

during each event at each of the water sampling locations described in Section 2.2.1.2. 

Water samples were collected as grab samples from a valved tap directly into sample containers from

each location. Each sample collected for BTEX analysis was collected in 20-milliliter volatile 

organic analysis (VOA) vials containing hydrochloric acid (HCl) to acidify the sample to a pH of less 

than 2. Water was introduced into the sample containers gently to reduce agitation that may drive off 

volatile organic compounds (VOCs). Each vial was filled, and then tap checked for bubbles. If any

air bubbles were present, the sample was recollected. The second sample vial served as a backup to 

the original sample in the event that one vial was broken or its integrity was otherwise compromised. 

Water samples collected to analyze for PAHs were contained in two 1-liter glass jars. Again, the 

second sample bottle served as a backup to the original sample in the event that one bottle was broken 

or its integrity otherwise compromised. 

Water samples collected for physical and chemical parameters necessary to fulfill objective S2 were 

collected in one 500-milliliter plastic jar and one 1-liter plastic jar. 

Prior to collecting water samples from a given location, the valve on the tap was opened and water 

was purged to flush any stagnant water out of the tap. 

17 
Gas Samples 

Gas samples were collected during each sampling event at each of the gas sampling locations 

described above in Section 2.2.1.1 (GA1, GM1, and GZ1). Gas sampling times were based on a 

maximum sampling time of 50 minutes per location and take into account the water residence time 

through each of the associated aerated components. 

Samples were collected according to the series of National Institute of Occupational Safety and 

Health (NIOSH) gas sampling methods that incorporate charcoal tube adsorption for specific groups 

of VOCs and pre-filtered XAD resin adsorption for napthalene. Sampling was conducted in 

accordance with modified NIOSH Methods 1501 for BTEX and 5515 for napthalene. 

Two charcoal tube adsorbent samples for BTEX and two pre-filtered sorbent resin samples for 

naphthalene were taken at different sample volumes (20 and 50 liters) from each gas sampling 

location. These volumes were calculated by Institut Fresenius to achieve desired detection limits. 

Therefore, two samples of differing volumes were collected for BTEX at each gas sampling location 

and two samples of differing volumes were collected for naphthalene at each gas sampling location, 

for a total of four exhaust gas adsorbent samples collected at each gas sample location per sampling 

event. 

Leak checks were performed before and after collection of each gas sample. After the post-sampling 

leak check, the traps were sealed with end caps and returned to their glass containers for storage and 

transport. 

Analytical Methods 

Table 1 lists the analytical methods used for samples collected during the evaluation. 

18 
 

2.2.3 

Table 1 Analytical Methods 

Matrix Parameter Reference Method Method Name 

BTEX SW-846 

5030B/8260B 

Purge-and-trap; Capillary 

Column; GC/MS 

PAH 

SW-846 

3520C/8270C 

Continuous Liquid-Liquid 

Extraction; Capillary Column; 

GC/MS 

pH MCAWW 150.1 pH 

Major Cations SW-846 

3010A/6010B 

Metals by ICP/Atomic Emission 

Spectroscopy 

(Na, K, Ca, Fe, Mg, Mn) 

Water Major Anions SM 4110B 

Ion Chromatography (Cl-

, F­, 

NO2 

-

, NO3 

-

, PO4 

-3, SO4 -2) 

BTEX NIOSH 1501 

SW-846 8260B 

Extraction of Charcoal 

Adsorbent with CS2; 

BTEX by GC/MS 

Gas Naphthalene NIOSH 5515 

SW-846 8270C 

Extraction of XAD Resin with 

Toluene;Naphthalene by 

GC/MS 

Notes: 

GC/MS Gas chromatography/mass spectrometry

ICP Inductively coupled plasma 

MCAWW Methods for the Chemical Analysis of Water and Wastes 

NIOSH National Institute of Occupational Safety and Health 

SM Standard Methods for the Examination of Water and Wastewater 

BTEX Benzene, toluene, ethylbenzene, and total xylenes

PAH Polyaromatic hydrocarbons 

Quality Assurance and Quality Control Program 

Quality control checks were an integral part of the bilateral SITE evaluation. These checks and 

procedures focused on the collection of representative samples absent of external contamination and 

on the generation of comparable data. The QC checks and procedures conducted during the 

evaluation were of two kinds: (1) checks controlling field activities, such as sample collection and 

shipping; and (2) checks controlling laboratory activities, such as extraction techniques and analysis. 

The results of the field and laboratory QC checks are summarized in Section 2.3.3. Figure 4 presents 

the data reduction, validation, and reporting scheme for this demonstration. 

19 
	
 
		
 


	 

 

 	 
	 	   



 	 

  	 

  	 

    
	 


   
	 
 

   
	 


  	  

	   

  


 	   	  

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2.2.3.1 Field Quality Control Checks 

As a check on the quality of field activities, including sample collection, shipment, and handling, 

three types of field QC samples (field blanks and trip blanks) were collected. In general, these QC 

checks assess the potential for contamination of samples in the field and ensure that the degree to 

which the analytical data represent site conditions is known and documented. 

2.2.3.2 Laboratory Quality Control Checks 

Laboratory QC checks are designed to assess the precision and accuracy of the analysis, to 

demonstrate the absence of interferences and contamination from glassware and reagents, and to 

ensure the comparability of data. Laboratory-based QC checks consisted of method blanks, matrix 

spikes/matrix spike duplicates, surrogate spikes, blank spikes/blank spike duplicates, and other checks 

specified in the analytical methods. The laboratory also conducted initial calibrations and continued 

calibration checks according to the specified analytical methods. 

2.2.3.3 Field and Laboratory Audits 

No project specific audits were conducted during this technology demonstration. However, general 

systems audits of Institut Fresenius laboratories have been conducted under other bilateral technology 

demonstrations. 

2.3 EVALUATION RESULTS AND CONCLUSIONS 

This section describes the operating conditions, results, data quality, and conclusions of the bilateral 

SITE evaluation of the biological reactor system technology. 

2.3.1 Operating Conditions 

The AQUABOX 50 and MARABU biological reactors are active technologies that require operation 

and maintenance of the system components. During this bilateral SITE evaluation, the biological 

reactor system was operated at conditions determined by the developer, SWD. 

21 
2.3.1.1 Treatment System Configuration 

The configuration of the biological reactor system components is shown in Figure 3. 

2.3.1.2 Operating Parameters 

The developer and facility owner monitored the biological reactor system throughout the 

demonstration. System operating parameters included individual well extraction rates and overall 

groundwater flow rates. Various operating parameters obtained from the on-site operators of the 

system were monitored to collect the operational data needed to fulfill the objectives of this 

evaluation. These parameters included: 

(1) Extracted groundwater flow rates (for each of five recovery wells): Groundwater 

flow rates were read at the inlet port to each reactor when the influent groundwater 

sampling was performed (i.e. one measurement per day per event at each location). 

(2) Ventilation gas flow rates (for AQUABOX 50, MARABU, and intermediate storage 

tank): Gas flow rates were read at the outlet port from each reactor and the 

intermediate storage tank, when the influent groundwater sampling was performed 

(i.e. one measurement per day per event at each location). 

(3) Electric power consumption for the evaluation system: Electrical power 

measurements were read and recorded by the field team at the beginning and end of 

each sampling event to determine power consumption. Cost information was 

compiled by Probiotec from the power consumption data recorded and reviewed by 

Tetra Tech. 

The flow meters were calibrated by a state calibration office ("Staatliches Eichamt") before they were 

purchased from the vendor and were ready for immediate use. On-site operating personnel were 

responsible for maintaining all existing monitoring instruments. 

22 
2.3.2 Results and Discussion 

This section presents the results of the bilateral SITE evaluation of the biological reactor technologies 

at Duesseldorf, Germany. The results are presented by and have been evaluated in relation to the 

project objectives. The specific primary and secondary objectives are shown at the top of each 

section in italics, followed by a discussion of the objective-specific results. 

2.3.2.1 Primary Objectives 

P1 Demonstrate greater than 95 percent average removal efficiency for total BTEX and greater than 

60 percent average removal efficiency for the three most prevalent PAHs (acenaphthene, 

fluorene, and naphthalene) for the overall system. The overall system includes the AQUABOX 

50, MARABU, and sand filter, but excludes the activated carbon system component. 

The SWD AQUABOX 50 and MARABU packed biological reactor system was designed to reduce 

total BTEX concentrations in water by greater than 95 percent and total PAH concentrations in water 

by greater than 60 percent. Based on the relatively low initial PAH concentrations in the groundwater, 

detection limit resolution was a concern for total PAH measurement. As such, removal efficiencies 

were only calculated for the three PAHs present at the highest initial concentrations: acenaphthene, 

fluorene, and naphthalene. Removal efficiencies were calculated using the average influent 

concentration and effluent concentration of the three critical PAHs and total BTEX. 

The removal efficiencies for the target PAHs, acenaphthene, fluorene, and naphthalene ranged from 

>99.7 percent to >99.9 percent, >98.9 percent to >99.4 percent, and >99.6 percent to >99.9 percent, 

respectively. The removal efficiency of total BTEX ranged from >99.5 percent to >99.7 percent. 

(Note: removal efficiencies that are calculated from effluent concentrations less than the detection 

limit are designated as A>@. Using the removal efficiency formula in Section 2.1.2, an influent 

concentration minus a less than the detection limit (A<@) effluent concentration is presented as a A>@

difference.) Table 2 presents the ranges and means of the removal efficiencies for these critical 

compounds, and Table 3 presents the influent concentrations, effluent concentrations, and calculated 

removal efficiency for each sampling event. Table 4 presents the flow rates [Q, see the removal 

efficiency equation in Section 2.1.2, where Q equals the flow rate of groundwater through the system 

(sum of flows for each of the five influent flow lines - WA1 through WA4 and WM1)] at the five 

influent wells for each sampling event that were used to calculate an average influent concentration. 

(Note: The effectiveness of the activated carbon filter in removing these contaminants from the water 

stream was not evaluated because activated carbon filters are conventional technology). Ranges and 

23 
averages of removal efficiencies for analytes that had concentrations less than the detection limits 

were calculated using half of the detection limit for each nondetect result. 

Table 2 Range and Mean Mass Removal Efficiencies for the Total System 

Compound Range (Percent) Mean (Percent) 

Acenaphthene >99.7 - >99.9 >99.7 

Fluorene >98.9 - >99.4 >99.1 

Naphthalene >99.6 - >99.9 >99.8 

Total BTEX >99.5 - >99.7 >99.6 

P2 Measure the removal efficiencies for BTEX and the three most prevalent PAHs across each of the 

treatment units, including the AQUABOX 50, MARABU, and sand filter. 

The average removal efficiencies for the 4-week demonstration period were calculated on an 

individual mass basis for the target PAHs and total BTEX across each of the biological treatment 

units and the sand filter units (Table 5). The removal efficiencies for the PAHs were significantly 

lower than the removal efficiencies of the total BTEX, most likely due to volatization of the BTEX to 

air or increased 

24 
Table 3 Summary of Removal Efficiency Calculations for the Total System 

Compound Sampling Event No. 1 Sampling Event No. 2 Sampling Event No. 3 

Influent 

Conc. 

(Fg/L) 

Effluent 

Conc. 

(Fg/L) 

Removal 

Efficiency 

(%) 

Influent 

Conc. 

(Fg/L) 

Effluent 

Conc. 

(Fg/L)

 Removal 

Efficiency 

(%) 

Influent 

Conc. 

(Fg/L) 

Effluent 

Conc. 

(Fg/L) 

Removal 

Efficiency 

(%) 

Influen

Conc

(Fg/L

Acenaphthene 193 <1.0 >99.7 171.4 <1.0 >99.7 184 <0.5 >99.9 157 

Fluorene 57 <1.0 >99.1 45.3 <1.0 >98.9 52.1 <0.5 >99.5 42.1 

Naphthalene 208.5 <1.0 >99.8 129 <1.0 >99.6 248 <0.5 >99.9 184 

Benzene 76.6 <1.0 >99.3 48.1 <1.0 >99.0 88.6 <1.0 >99.4 47.8 

Toluene 494.5 1.8 99.6 420 <1.0 >99.9 403 <1.0 >99.9 462 

Ethylbenzene 26.6 <1.0 >98.1 22.1 <1.0 >97.7 27.9 <1.0 >98.2 28.2 

Total xylenes 222.8 1.0 99.6 182 1.0 99.5 206 1.0 99.5 245 

Total BTEX 820 3.8 >99.5 672 2.5 >99.6 726 2.5 >99.7 783 

Notes: Conc. Concentration 

Fg/L Microgram per liter 

% Percent BTEX Benzene, toluene, ethylbenze and total xylenes 

Table 4 Summary of the Influent Flow Rates to the System 

Total Influent Flow Rates Sampling Event No. 1 

Influent Flow Rate (m3/hr) 

Sampling Event No. 2 

Influent Flow Rate (m3/hr) 

Sampling Event No. 3 

Influent Flow Rate (m3/hr) 

Total (sum of the 4 influent flow rates) to the AQUABOX 50 unit 

20.7 19.9 17.7 

One influent flow rate to the MARABU unit 2.99 2.95 2.96 Total (sum of the 5 influent flow rates) to the system 23.7 22.9 20.7 

Notes: m3/hr Cubic meters per hour 

25 
biodegradation. The removal efficiencies of the AQUABOX 50 unit for acenaphthene, fluorene and 

naphthalene ranged from 76.0 percent to >99.8 percent, 80.7 percent to >99.3 percent, and 91.0 percent to 

>99.8 percent, respectively. The removal efficiency for total BTEX of the AQUABOX 50 unit ranged 

from 92.1 percent to >97.1 percent. The removal efficiencies of the MARABU unit for acenaphthene, 

fluorene, and napthalene ranged from 47.0 percent to 66.1 percent, 53.6 percent to 71.5 percent, and 75.3 

percent to 90.2 percent, respectively. The removal efficiency for total BTEX of the MARABU unit 

ranged from 67.6 percent to 74.6 percent. The removal efficiencies of the sand filter unit for 

acenaphthene, fluorene, and naphthalene ranged from >99.0 percent to >99.4 percent, >95.7 percent to 

>97.1 percent, and >97.5 percent to >98.9 percent, respectively. The removal efficiency for total BTEX 

of the sand filter unit ranged from >40.5 percent to >94.6 percent. (Note: the flow rates, Q,used in the 

removal efficiency calculating, are presented in Table 4. See the equation in Section 2.1.2). 

Because the three target PAHs and BTEX were detected at low concentrations in the influent well to the 

sand filter unit, the associated calculated removal efficiencies are not significant. The concentrations of 

these target analytes both in the influent wells and effluent from the sand filter unit were either low or less 

than the detection limit, resulting in removal efficiencies that are not meaningful. Table 6 presents 

influent and effluent analyte concentrations and removal efficiencies per event. 

2.3.2.2 Secondary Objectives 

The secondary project objectives and the associated noncritical measurement parameters required to 

achieve those objectives were presented in Section 2.1.2. The results of each secondary objective are 

discussed in the following subsections. 

S1 Determine the percent of total BTEX and naphthalene that is stripped from each aerated 

component of the system 

Aeration systems provide air flow through the AQUABOX 50, MARABU, and intermediate storage tank. 

Airflow strips BTEX and to a lesser extent PAHs (acenaphthene, fluorene, and naphthalene) from the 

groundwater. Resulting exhaust gases are discharged to the atmosphere through activated carbon filters. 

To assess the quantity of the total BTEX and volatile PAHs (acenaphthene, fluorene, and naphthalene) 

that are removed by air stripping, individual exhaust gas samples were collected from each of the system 

components at locations before the activated carbon units (GA1, GM1, and GZ1). These exhaust gas 

samples were collected on the same schedule as the influent/effluent water sampling activities (once per 

26 
week for a 4-week period). Results of the stripping efficiency calculations are presented in Table 7. 

Summary results were expressed as a mean and a range of the percentage stripped over the 4-week 

evaluation period are presented in Table 8. 

Percentages of the PAHs and BTEX that were removed from the groundwater by the biological reactor 

and percentages removed to the air due to the aeration in the biological reactors were determined. Table 8 

presents the percentages of the contaminants that were volatilized, or stripped, to the air. The PAHs, 

which are semivolatile, were stripped at lower percentages than the volatile BTEX. The PAHs detected in 

the gas were all either lower than the detection limit or detected at low concentrations. 

Table 5 Range and Mean Removal Efficiencies for the System Components 

Compound 

Percent Removal Efficiencies 

Range (Percent) Mean (Percent) 

AQUABOX 50 Unit 

Acenaphthene 76.0 - >99.8 >84.6 

Fluorene 80.7 - >99.3 >87.7 

Naphthalene 91.0 - >99.8 >94.8 

Total BTEX 92.1 - >97.1 >94.8 

MARABU Unit 

Acenaphthene 47.0 - 66.1 52.8 

Fluorene 53.6 - 71.5 64.4 

Naphthalene 75.3 - 90.2 82.6 

Total BTEX 67.6 - 74.6 71.7 

Sand Filter Unit 

Acenaphthene >99.0 - >99.4 >99.2 

Fluorene >95.7 - >97.2 >96.5 

Naphthalene >97.5 - >98.9 >98.2 

Total BTEX >40.5 - >94.6 >80.0 

Notes: 

BTEX Benzene, toluene, ethylbenzene, and total xylenes

27 
Table 6 - Summary of Mass Removal Efficiency Calculations for System Components 

Compound Sampling Event No. 1 Sampling Event No. 2 Sampling Event No. 3 

Influent 

Conc. 

(Fg/L) 

Effluent 

Conc. 

(Fg/L) 

Mass 

Removal 

Efficiency 

(%) 

Influent 

Conc. 

(Fg/L) 

Effluent 

Conc. 

(Fg/L) 

Mass 

Removal 

Efficiency 

(%) 

Influent 

Conc. 

(Fg/L) 

Effluent 

Conc. 

(Fg/L) 

Mass 

Removal 

Efficiency 

(%) 

In

C

(F

AQUABOX 50 Unit Acenaphthene 171 40.9 76.1 163 39.1 76 142.0* 19.3* 86.4* 139 Fluorene 50.5 9.3 86.1 47.1 9.1 80.7 41.0 4.5 89.0 38.0 Naphthalene 134 8.3 93.8 114 10.3 91.0 114.3* 6.1* 94.7* 126Benzene 42.2 2.7 93.6 35.9 2.1 94.1 24.4 <1.0 >97.9 21.3 Toluene 555 39.6 92.9 527 32.1 93.9 491.1 13.0 97.4 499 Ethylbenzene 24.9 3.1 87.5 24.0 2.7 88.8 24.8 1.4 94.4 27.1 Total xylenes 234 22.1 90.5 216 20.3 90.6 224.9 8.1 96.4 254Total BTEX 856 67.5 92.1 803 57.2 92.9 765.2 23.0 97.0 802 MARABU Unit Acenaphthene 347.3 173.6 50.0 394.9 204.5 48.2 354.2* 120.1* 66.1* 356

Fluorene 101.2 33.8 66.6 111.9 38.3 65.8 96.8 27.6 71.5 88.2 

Naphthalene 720.7 95.3 86.8 848.6 186.0 78.1 787.4* 77.1* 90.2* 836

Benzene 312.0 72.5 76.8 346.1 94.3 72.8 347.0 109.9 68.3 487 

Toluene 79.4 16.9 78.7 68.0 14.6 78.5 48.3 15.0 68.9 129

Ethylbenzene 38.5 13.2 65.7 40.0 15.1 62.3 40.3 13.8 65.8 48.2 

Total xylenes 149.3 48.2 67.7 149.1 54.2 63.6 131.8 45.3 65.6 167

28
Table 6 - Summary of Mass Removal Efficiency Calculations for System Components (Continue

Compound Sampling Event No. 1 Sampling Event No. 2 Sampling Event No. 3 

Influent 

Conc. 

(Fg/L) 

Effluent 

Conc. 

(Fg/L) 

Mass 

Removal 

Efficiency 

(%) 

Influent 

Conc. 

(Fg/L) 

Effluent 

Conc. 

(Fg/L) 

Mass 

Removal 

Efficiency 

(%) 

Influent 

Conc. 

(Fg/L) 

Effluent 

Conc. 

(Fg/L) 

Mass 

Removal 

Efficiency 

(%) 

In

C

(F

Total BTEX 579.2 150.8 74.0 603.2 178.2 70.5 567.4 184.0 67.6 831

Sand Filter Unit Acenaphthene 49.4 <1.0 >99.0 50.1 <1.0 >99.0 37.7* <0.5* >99.3* 39.6 

Fluorene 11.8 <1.0 >95.8 11.5 <1.0 >95.7 9.0 <0.5 >97.2 8.6 Naphthalene 20.4 <1.0 >97.5 20.6 <1.0 >97.6 23.0* <0.5* >98.9* 23.4 Benzene 7.4 <1.0 >93.2 6.6 <1.0 >92.4 9.9 <1.0 >94.9 <1.0 Toluene 25.8 1.8 93.0 19.1 <1.0 >97.4 8.8 <1.0 >94.3 2.2 Ethylbenzene 3.0 <1.0 >83.3 3.1 <1.0 >83.9 2.3 <1.0 >78.3 <1.0 Total xylenes 18.7 1.0 94.7 17.2 1.0 94.2 9.9 1.0 89.9 1.0 Total BTEX 54.9 3.8 >93.1 46.0 2.5 >94.6 30.9 2.5 >91.9 4.2 

Notes: * MS/MSDs for these compounds did not meet the QA objectives during this event. Fg/L Micrograms per liter % Percent 

29 
The results indicate removal efficiencies for the PAHs in groundwater ranging between 76.0 percent and 

99.8 percent for the AQUABOX 50, and 48.2 and 90.2 percent for the MARABU. The gas concentration 

for PAHs were either less than the detection limit or very low indicating a minimal removal due to 

stripping. The BTEX gas concentrations stripped from the AQUABOX 50 range from 0.2 percent to 1.0 

percent; BTEX gas concentrations stripped from the MARABU ranged from 6.9 percent to 8.8 percent. 

S2 Document the physical and chemical characteristics of the treated water that could affect the 

performance of the evaluation system and document how these parameters change with 

treatment. 

Parameters measured include pH, major cations (Na, K, Ca, Fe, Mg, Mn), and anions (Cl-

, F-, NO2

-

, NO3

-

, 

PO4

3-, SO42-). To accomplish this objective, samples were collected once per week for the influent to 

(WA1 through WA4, WM1) and effluent from (WK) the treatment system during the 4-week sampling 

program. These samples were analyzed for each of the parameters identified above; results are presented 

as a mean and a range of the four measured values (see Table 9). 

S3 Document the capital and operating costs of the SWD AQUABOX 50 and MARABU packed 

biological reactor system based on observations during the evaluation and data from the 

engineering designers and from the operator of the system. 

Capital and operating costs of this system, as applied at the SWD site, were estimated based on operating 

requirements observed during the evaluation and on capital and operating cost information available from 

the designers and operator of the system. The initial capital cost of the biological reactor system at the 

Stadtwerke Duesseldorf AG Site, including site preparation, permitting and regulatory costs, construction 

materials and labor, and startup was about 218,700 DM ($113,900 U.S. assuming a 1.92 DM to $1 U.S. 

exchange rate). Monitoring and other periodic costs amounted to about 37,000 DM/year ($19,300 

U.S./year). 

30 
Table 7 Stripping Efficiencies for Each Component of the Treatment System 

Compound 

Sampling Event No. 1 Sampling Event No. 2 Sampling Event No. 3 Sampling Event No. 4 

Inf. H2O 

mg/hr 

Gas 

mg/hr 

SE 

% 

Inf. 

H2O 

mg/hr 

Gas 

mg/h 

SE 

% 

Inf. H2O 

mg/hr 

Gas 

mg/hr 

SE 

% 

Inf. 

H2O 

mg/hr 

Gas 

mg/hr 

SE 

% 

AQUABOX 50 Unit 

Acenaphthene 3510 <0.5 <0.01 1810 <1.0 <0.06 1690 <0.5 <0.02 4720 <0.5 <0.01 

Fluorene 1040 <0.5 <0.04 525 <0.4 <0.08 488 <0.5 <0.1 1290 <0.5 <0.04 

Naphthalene 2740 <0.5 <0.02 1270 <1.1 <0.08 1360 <0.5 <0.04 4300 <0.5 <0.02 

Benzene 866 2.7 0.3 400 3.4 0.9 290 <1.2 <0.4 724 1.3 0.2 

Toluene 11400 43.9 0.4 5870 54.4 0.9 5840 25.0 0.4 16900 25.0 0.1 

Ethylbenzene 511 3.8 0.7 268 5.0 0.4 295 2.88 1.0 919 2.9 0.3 

Total xylenes 4790 22.0 0.5 2410 26.6 1.1 2680 13.0 0.5 8650 14.8 0.2 

Total BTEX 17600 72.4 0.4 8950 89.5 1.0 9110 42.0 0.5 27200 44.0 0.2 

MARABU Unit 

Acenaphthene 1040 1.4 0.1 1160 1.6 0.1 1050 2.4 0.2 1070 2.4 0.2 

Fluorene 304 <0.2 <0.06 330 <0.2 <0.06 287 <0.2 <0.06 265 <0.2 <0.08 

Naphthalene 2160 7.1 0.3 2500 6.2 0.2 2330 9.2 0.4 2510 9.4 0.4 

Benzene 936 50.3 5.4 1020 54.1 5.3 1030 63.9 6.2 1460 92.8 6.4 

Toluene 238 13.4 5.6 201 12.1 6.0 143 11.8 8.3 388 21.5 5.5 

Ethylbenzene 116 11.1 9.6 118 12.6 10.7 119 10.6 8.9 145 17.6 12.1 

Total xylenes 448 30.3 6.8 440 30.1 6.8 390 26.8 6.9 502 44.0 8.8 

Total BTEX 1740 139 8.0 1780 152 8.5 1680 138.6 8.3 2500 173.0 6.9 

Sand Filter Unit 

Acenaphthene 1160 <0.3 <0.02 706 <0.3 <0.04 560 <0.3 <0.06 1460 <0.3 <0.02 

Fluorene 278 <0.3 <0.1 162 <0.3 <0.2 134 <0.3 <0.2 318 <0.3 <0.1 

Naphthalene 480 1.5 0.3 290 1.5 0.5 342 1.6 0.5 864 1.6 0.2 

Benzene 174 7.3 4.2 93 10.2 11.0 147 15.7 10.7 <18 15.7 <87 

Toluene 607 18.8 3.1 269 23.5 8.7 131 12.7 9.7 <81 12.7 <15.7 

Ethylbenzene 71 3.0 4.2 44 4.1 9.3 34 3.6 10.6 <18 3.6 <20.0 

Total xylenes 440 12.4 2.8 243 14.4 5.9 147 11.9 8.1 37 11.9 32.2 

Total BTEX 1290 41.5 3.2 649 52.2 8.0 459 44.0 9.6 155 44.0 28.4 

Notes: H2O = Water; mg/hr = Milligrams per hour; SE = Stripping Efficiency by Aeration; % = Percent 

31
Table 8 Ranges and Mean Stripping Efficiencies for Each Component 

Compound 

Percent Stripping Efficiencies 

Range (Percent) Mean (Percent) 

AQUABOX 50 Unit 

Acenaphthene >0.005 - > 0.03 >0.01 

Fluorene >0.02 - >0.05 >0.03 

Naphthalene >0.009 - >0.04 >0.02 

Total BTEX 0.2 - 1.0 0.5 

MARABU Unit 

Acenaphthene 0.1 - 0.2 0.2 

Fluorene >0.03 - >0.04 >0.03 

Naphthalene 0.2 - 0.4 0.3 

Total BTEX 6.9 - 8.8 8.0 

Sand Filter Unit 

Acenaphthene >0.01 - >0.03 >0.02 

Fluorene >0.05 - >0.1 >0.7 

Naphthalene 0.2 - 0.5 0.4 

Total BTEX 3.2 - 28.4 12.3 

Notes: 

BTEX Benzene, toluene, ethylbenzene, and total xylenes

32 
Table 9 - Physical and Chemical Characteristics of the Treated Water 

Parameter Units Sampling Location 

Influent - WA1 Influent -WA2 Influent - WA3 Influent - WA 4 Influent - WM1 

Range Mean Range Mean Range Mean Range Mean Range Me

pH 7.01-7.18 7.11 6.88-6.95 6.92 6.95-7.03 6.99 6.94-7.98 7.24 6.95-6.99 6.

Temp. EC 13.7-14.2 13.9 13.7-14.6 14.0 13.9-14.1 14.0 14.6-14.9 14.7 13.4-13.8 13

Conductivity high 4th 

FS/cm 

649-864 718 647-859 712 754-1010 835 697-927 766 626-831 68

Redox-potential mV -210 - -102 -149 -159 - -90 -113 -139 - -87 -115 -153 - -100 -122 -215 - -118 -1

Dissolved O2 mg/L 0.1-0.5 0.3 0.14-0.5 0.3 0.2-0.99 0.6 0.1-0.4 0.2 0.1-0.7 0

Na mg/L 59.7-61.1 60.3 60.3-62.6 61.4 63.8-64.8 64.3 62.6-64.6 63.9 58.0-60.7 59

K mg/L 13.0-17.3 14.6 12.9-13.5­ 13.1 21.9-22.4 22.0 9.0-9.8 9.3 13.0-13.9 13

Ca mg/L 143-149 146 141-144 142 172-179 175 147-152 149 134-138 13

Fe mg/L 3.8-4.1 4.0 6.2-6.6 6.4 10.3-11.2 10.6 7.8-8.9 8.4 6.0-6.2 6

Mg mg/L 16.4-17.1 16.7 16.3-16.6 16.5 18.3-19.2 18.7 18.8-19.8 19.4 15.5-15.9 15

Mn mg/L 0.77-0.79 0.78 1.5-1.5 1.5 2.1-2.1 2.1 1.5-1.5 1.5 1.1-1.1 1

Cl mg/L 86-93 88 73-78 75 68-73 71 85-89 87 75-79 7

F mg/L 0.36-0.37 0.37 0.63-0.68 0.65 0.73-0.75 0.74 0.3-0.3 0.3 .66-.70 0.

Nitrite mg/L <0.02-<0.02 <0.02 <0.02-0.06 0.02 0.04-0.12 0.08 <0.02-.11 0.05 0.1-0.1 0

Nitrate mg/L <0.3-<0.3 <0.3 1.3-1.4 1.3 1.5-1.9 1.7 0.9-1.6 1.3 <0.3-<0.3 <0

Phosphate mg/L 0.3-0.5 0.4 0.1-0.6 0.4 0.4-0.7 0.6 0.5-0.7 0.6 0.9-1.1 1

33
Table 9 - Physical and Chemical Characteristics of the Treated Water (Continued)

Parameter Units Sampling Location 

Influent - WA1 Influent -WA2 Influent - WA3 Influent - WA 4 Influent - WM1 

Range Mean Range Mean Range Mean Range Mean Range Me

Sulfate mg/L 185-192 189 193-204 199 298-313 308 187-199 193 167-173 17

CaCO3 mmol/L 5.11-5.17 5.15 4.9-5.0 5.0 5.23-5.28 5.26 5.61-5.66 5.64 5.27-5.46 5.

Lead Fg/L <5 - <5 <5 <5 - <5 <5 <5 - <5 <5 <5 - <5 <5 <5 - <5 <

Copper Fg/L <5 - 16 6 <5 - <5 <5 <5 - <5 <5 <5 - <5 <5 <5-20 7 

Cadmium Fg/L <0.5 - <0.5 <0.5 <0.5 - <0.5 <0.5 <0.5 - <0.5 <0.5 <0.5 - <0.5 <0.5 <0.5 - <0.5 <0

Zinc Fg/L 80-193 117 204-639 360 343-690 446 250-310 268 129-990 42

Nickel Fg/L <5 - <5 <5 <5-13 5 <5-5 3 <5-6 3 <5 - <5 <

Chromium Fg/L <5 - <5 <5 <5 - <5 <5 <5 - <5 <5 <5 - <5 <5 <5 - <5 <

Arsenic Fg/L 2-3 2 1-1 1 2-2 2 3-4 4 3-3 3 

Mercury Fg/L <0.2-<0.2 <0.2 <0.2-<0.2 <0.2 <0.2-<0.2 <0.2 <0.2-<0.2 <0.2 <0.2-<0.2 <0

Notes: Fg/L Micrograms per liter FS/cm Microsiemens per centimeter mg/L Milligrams per liter EC Degree Celsius mmol Micromole 

34 
2.3.3 Data Quality 

This section summarizes the data quality for groundwater samples collected and analyzed during the 

biological reactor system bilateral SITE demonstration. The purpose of this data quality assessment was 

to identify any limitations of the data presented in this report or qualifications of the conclusions based on 

known information on data quality. 

2.3.3.1 Groundwater Samples 

For the groundwater samples, both field and laboratory QC samples were collected. Field QC samples 

included trip blanks and field blanks, as well as MS/MSDs. 

Because BTEX in groundwater was one of the primary contamination concerns at the site, field blanks 

and trip blanks were collected to monitor whether field techniques or sample shipping introduced VOCs 

to field samples. Toluene was the only compound detected in the field blanks and trip blanks above the 

detection limit at 2.9 Fg/L and 1.8 micrograms per liter (Fg/L), respectively. These results suggest that 

small concentrations of toluene may have been introduced by field techniques or sample shipping. Trip 

and field blank results for the remaining analytes were all less than detection limits. 

One MS/MSD sample was taken during each of the four sampling events to assess the precision and 

accuracy of the recoveries for the critical analytes and matrix interferences. MS/MSD sample results, 

presented in Tables 10 thru 14, indicate that the recoveries and relative percent differences (RPDs) for the 

critical analytes were within the pre-established QC limits for three of the four samples. The MS/MSD 

recoveries and RPDs for 7 of the 8 critical analytes in samples taken during Event 3 were outside of the 

acceptance criteria. The volatiles, BTEX, were reanalyzed and MSD recoveries were all within range. 

The PAHs were not reanalyzed; acenaphthene and naphthalene were below the lower QC limit. 

Therefore, the results for these two PAHs in Event 3 could be biased low. 

35 
2.3.3.2 Gas Samples 

The primary QC samples processed in relation to the gas samples included field blanks, trip blanks and 

MS/MSD samples. All the field and trip blanks had analytical results less than detection limits for 

contaminants of concern. Therefore, introduction of contaminants by field or laboratory techniques was 

unlikely. All the MS/MSD samples met the QA objectives, as shown in Tables 15 through 18, indicating 

that general data quality was good and that the sample data are useable without qualification. 

Table 10 Matrix Spike/Matrix Spike Results, Duplicate Event 1 

Compound Field 

Sample 

(Fg/L) 

MS 

(Fg/L) 

MSD 

(Fg/L) 

MS 

Recovery 

(%) 

MSD 

Recovery 

(%) 

Recovery 

Acceptance 

Criteria 

RPD RPD 

Acceptance 

Criteria 

Acenaphthene 0.24 8.37 9.04 81.3 88.8 60-132 7.7 #30 

Fluorene 0.00 8.25 8.61 82.5 86.1 71-108 4.3 #30 

Naphthalene 0.00 6.87 7.28 68.7 72.8 35-120 5.8 #30 

Benzene 9.0 17.9 19.4 89.9 105.3 80-120 8.2 #30 

Toluene 2.0 11.6 11.2 92.9 88.4 80-120 4.0 #30 

Ethylbenzene 5.8 15.3 15.6 96.8 99.8 80-120 1.9 #30 

m-,p-Xylene 0.5 19.4 19.8 94.9 96.5 80-120 1.6 #30 

o-Xylene 0.9 9.9 10.0 93.8 95.7 80-120 1.8 #30 

Notes: 

Fg/L Microgram per liter 

% Percent 

* Outside acceptance criteria 

MS Matrix spike 

MS Matrix spike duplicate 

RPD Relative percent difference 

36 
Table 11 Matrix Spike/Matrix Spike Results, Duplicate Event 2 

Compound Field 

Sample 

(Fg/L) 

MS 

(Fg/L) 

MSD 

(Fg/L) 

MS 

Recovery 

(%) 

MSD 

Recovery 

(%) 

Recovery 

Acceptance 

Criteria 

RPD RPD 

Acceptance 

Criteria 

Acenaphthene 0.00 9.36 8.30 93.6 83.0 60-132 12.0 #30 

Fluorene 0.00 8.99 8.00 89.9 80.0 71-108 12.0 #30 

Naphthalene 0.00 8.01 7.47 80.1 74.7 35-120 7.0 #30 

Benzene 2.1 41.9 42.0 100.4 100.4 80-120 0.2 #30 

Toluene 32.1 74.0 71.8 101.4 96.0 80-120 3.0 #30 

Ethylbenzene 2.7 43.1 41.6 103.3 99.4 80-120 3.6 #30 

 m-,p-Xylene 13.4 96.5 93.5 104.3 100.6 80-120 3.1 #30 

o-Xylene 6.9 48.1 44.9 107.3 99.0 80-120 6.9 #30 

Notes: 

Fg/L Microgram per liter 

% Percent 

* Outside acceptance criteria 

MS Matrix spike 

MS Matrix spike duplicate 

RPD Relative percent difference 

Table 12 Matrix Spike/Matrix Spike Duplicate Results, Event 3 

Compound Field 

Sample 

(Fg/L) 

MS 

(Fg/L) 

MSD 

(Fg/L) 

MS 

Recovery 

(%) 

MSD 

Recovery 

(%) 

Recovery 

Acceptance 

Criteria 

RPD RPD 

Acceptance 

Criteria 

Acenaphthene 0.24 8.37 9.04 81.3 88.8 60-132 7.7 #30 

Fluorene 0.00 8.25 8.61 82.5 86.1 71-108 4.3 #30 

Naphthalene 0.00 6.87 7.28 68.7 72.8 35-120 5.8 #30 

Benzene 9.1 32.3 15.1 234.3* 60.7* 80-120 72.5* #30 

Toluene 7.1 26.6 8.2 189.7* 11.4* 80-120 105.6* #30 

Ethylbenzene 2.1 25.8 13.4 242.5* 115.7* 80-120 63.3* #30 

 m-,p-Xylene 5.4 54.7 18.7 247.7* 67.0* 80-120 98.1* #30 

o-Xylene 3.7 26.9 9.8 242.2* 63.9* 80-120 93.1* #30 

Notes: 

Fg/L Microgram per liter MS Matrix spike 

% Percent MSD Matrix spike duplicate 

* Outside acceptance criteria RPD Relative percent difference 

37 
 

Table 13 Matrix Spike/Matrix Spike Duplicate Results, Event 3 Retest 

Compound Field 

Sample 

(Fg/L) 

MS 

(Fg/L) 

MSD 

(Fg/L) 

MS 

Recovery 

(%) 

MSD 

Recovery 

(%) 

Recovery 

Acceptance 

Criteria 

RPD RPD 

Acceptance 

Criteria 

Acenaphthene 37.70 54.94 44.67 86.2 34.9* 60-132 20.6 #30 

Fluorene 8.95 25.77 21.76 84.1 64.1 71-108 16.9 #30 

Naphthalene 22.95 39.71 23.65 83.8 3.5* 35-120 50.7* #30 

Benzene 9.9 1.3 28.7 108.1 95.0 80-120 8.7 #30 

Toluene 8.8 30.0 29.3 102.6 99.3 80-120 2.3 #30 

Ethylbenzene 2.3 22.9 22.3 105.1 102.0 80-120 2.7 #30 

m-,p-Xylene 6.0 48.1 46.5 105.7 101.7 80-120 3.4 #30 

o-Xylene 3.9 24.0 23.1 104.6 99.9 80-120 3.9 #30 

Notes: 

Fg/L Microgram per liter 

% Percent 

* Outside acceptance criteria 

MS Matrix spike 

MS Matrix spike duplicate 

RPD Relative percent difference 

Table 14 Matrix Spike/Matrix Spike Duplicate Results, Event 4 

Compound Field 

Sample 

(Fg/L) 

MS 

(Fg/L) 

MSD 

(Fg/L) 

MS 

Recovery 

(%) 

MSD 

Recovery 

(%) 

Recovery 

Acceptance 

Criteria 

RPD RPD 

Acceptance 

Criteria 

Benzene 0.3 19.0 17.5 94.3 86.7 80-120 8.3 #30 

Toluene 2.2 18.9 19.9 81.2 85.9 80-120 5.0 #30 

Ethylbenzene 0.2 20.2 19.1 102.3 96.5 80-120 5.8 #30 

 m-,p-Xylene 0.3 42.0 39.7 104.6 98.9 80-120 5.6 #30 

o-Xylene 0.5 20.3 19.4 103.1 98.8 80-120 4.2 #30 

Acenaphthene 0.08 8.39 8.68 83.1 86.0 60-132 3.4 #30 

Fluorene 0.01 8.08 8.52 80.7 85.1 71-108 5.3 #30 

Naphthalene 0.01 8.22 8.37 82.1 83.6 35-120 1.8 #30 

Notes: 

ug/L Microgram per liter MS Matrix spike 

% Percent MSD Matrix spike duplicate 

* Outside acceptance criteria RPD Relative percent difference 

38 
Table 15 Gas Matrix Spike/Matrix Spike Duplicate Results, Event 1 

Compound Field 

Sample 

(Fg/L) 

MS 

(Fg/L) 

MSD 

(Fg/L) 

MS 

Recovery 

(%) 

MSD 

Recovery 

(%) 

Recovery 

Acceptance 

Criteria 

RPD RPD 

Acceptance 

Criteria 

Acenaphthene 0.06 8.01 7.94 99.4 98.5 60-132 0.88 #30 

Fluorene 0.00 7.72 7.94 96.5 99.3 71-108 2.81 #30 

Naphthalene 0.09 7.99 7.82 98.8 96.6 35-120 2.15 #30 

Benzene 0.00 19.04 19.04 96.1 96.1 80-120 0.00 #30 

Toluene 0.03 19.64 20.06 95.0 97.0 80-120 2.12 #30 

Ethylbenzene 0.00 18.91 19.46 96.5 99.3 80-120 2.87 #30 

Total Xylenes 0.01 54.9 55.24 92.3 92.9 80-120 0.32 #30 

Notes: 

Fg/L Microgram per liter 

% Percent 

* Outside acceptance criteria 

MS Matrix spike 

MS Matrix spike duplicate 

RPD Relative percent difference 

Table 16 Gas Matrix Spike/Matrix Spike Duplicate Results, Event 2 

Compound Field 

Sample 

(Fg/L) 

MS 

(Fg/L) 

MSD 

(Fg/L) 

MS 

Recovery 

(%) 

MSD 

Recovery 

(%) 

Recovery 

Acceptance 

Criteria 

RPD RPD 

Acceptance 

Criteria 

Acenaphthene 0.06 7.82 7.93 97.0 98.4 60-132 1.40 #30 

Fluorene 0.00 7.75 7.40 96.9 92.5 71-108 4.62 #30 

Naphthalene 0.08 7.60 7.88 94.0 97.5 35-120 3.62 #30 

Benzene 0.00 19.08 18.96 96.3 95.7 80-120 0.63 #30 

Toluene 0.00 20.26 19.94 98.1 96.6 80-120 1.59 #30 

Ethylbenzene 0.00 19.63 19.45 100.2 99.3 80-120 0.92 #30 

Total Xylenes 0.00 54.03 53.0 91.5 89.7 80-120 0.99 #30 

Notes: 

Fg/L Microgram per liter 

% Percent 

MS Matrix spike 

MS Matrix spike duplicate 

RPD Relative percent difference 

39 
Table 17 Gas Matrix Spike/Matrix Spike Duplicate Results, Event 3 

Compound Field 

Sample 

(Fg/L) 

MS 

(Fg/L) 

MSD 

(Fg/L) 

MS 

Recovery 

(%) 

MSD 

Recovery 

(%) 

Recovery 

Acceptance 

Criteria 

RPD RPD 

Acceptance 

Criteria 

Acenaphthene 0.00 6.33 6.40 105.5 106.7 60-132 1.10 #30 

Fluorene 0.00 6.10 6.28 101.7 104.7 71-108 2.91 #30 

Naphthalene 0.09 6.52 6.92 107.2 113.8 35-120 5.95 #30 

Benzene 0.00 36.29 37.33 91.5 94.2 80-120 2.83 #30 

Toluene 0.03 39.02 38.93 94.4 94.2 80-120 0.23 #30 

Ethylbenzene 0.00 38.36 38.57 97.9 98.4 80-120 0.55 #30 

Total Xylenes 0.00 113.21 113.59 95.8 96.2 80-120 0.21 #30 

Notes: 

Fg/L Micrograms per liter 

% Percent 

MS Matrix spike 

MS Matrix spike duplicate 

RPD Relative percent difference 

Table 18 Gas Matrix Spike/Matrix Spike Duplicate Results, Event 4 

Compound Field 

Sample 

(Fg/L) 

MS 

(Fg/L) 

MSD 

(Fg/L) 

MS 

Recovery 

(%) 

MSD 

Recovery 

(%) 

Recovery 

Acceptance 

Criteria 

RPD RPD 

Acceptance 

Criteria 

Acenaphthene 0.09 8.25 8.21 102.0 101.5 60-132 0.49 #30 

Fluorene 0.00 7.90 7.89 98.8 98.6 71-108 0.13 #30 

Naphthalene 0.07 8.37 8.47 103.8 105.0 35-120 1.19 #30 

Benzene 0.00 38.39 38.58 96.8 97.3 80-120 0.49 #30 

Toluene 0.02 41.07 39.87 99.4 96.5 80-120 2.97 #30 

Ethylbenzene 0.01 41.55 40.82 106.0 104.2 80-120 1.77 #30 

Total Xylenes 0.03 120.41 117.04 101.9 86.3 80-120 8.29 #30 

Notes: 

Fg/L Microgram per liter 

% Percent 

MS Matrix spike 

MS Matrix spike duplicate 

RPD Relative percent difference 

40 
2.4 CONCLUSIONS 

This section presents the conclusions of the biological reactor system. The conclusions for each objective 

are summarized below. 

$ The removal efficiencies for the three target PAHs, acenaphthene, fluorene and 

napthalene, and for total BTEX were all greater than 99 percent. These removal 

efficiencies exceeded the target removal efficiencies of 60 percent for the PAHs and 95 

percent for the total BTEX. 

$ The removal efficiencies, for the three target PAHs and the total BTEX, were calculated 

for three components of the system, the AQUABOX 50, the MARABU and the sand 

filter. Removal efficiencies of the AQUABOX 50 for acenaphthene, fluorene and 

napthalene ranged from 70.4 percent to 99.8 percent, 75.2 percent to 99.2 percent, and 

91.0 percent to 99.8 percent, respectively. Removal efficiency for total BTEX of the 

AQUABOX 50 ranged from 92.3 percent to 97.0 percent. Removal efficiencies of the 

MARABU for acenapthene, fluorene, and napthalene ranged from 47.0 percent to 66.1 

percent, 53.6 percent to 71.5 percent, and 75.3 percent to 90.2 percent, respectively. 

Removal efficiency for total BTEX of the MARABU ranged from 67.6 percent to 74.6 

percent. Removal efficiencies of the sand filter unit for acenaphthene, fluorene, and 

napthalene ranged from 99.0 percent to 99.4 percent, 95.7 percent to 97.2 percent, and 

97.5 percent to 98.9 percent, respectively. Removal efficiency for total BTEX for the 

sand filter unit ranged from 28.6 percent to 94.6 percent. 

$ The stripping efficiencies (percent of influent mass stripped into the exhaust gas) for the 

three target PAHs and the total BTEX were calculated for the three components of the 

system. 

$ Stripping efficiencies of the AQUABOX 50 for acenaphthene, fluorene, and napthalene, 

ranged from <0.01 percent to <0.06 percent, <0.04 percent to <0.1 percent, and <0.02 

percent to <0.08 percent, respectively. Stripping efficiency for total BTEX of the 

AQUABOX 50 ranged from 0.2 percent to 1.0 percent. Stripping efficiencies of the 

MARABU for acenaphthene, fluorene, and napthalene, ranged from 0.1percent to 0.2 

percent, <0.06 percent to <0.08 percent, and 0.2 percent to 0.4 percent, respectively. 

Stripping efficiency for total BTEX of the MARABU ranged from 6.9 percent to 8.8 

percent. Stripping efficiencies of the sand filter for acenaphthene, fluorene, and 

napthalene, ranged from <0.02 percent to <0.06 percent, <0.1 percent to <0.2 percent, 

and 0.2 percent to 0.5 percent, respectively. Stripping efficiency for total BTEX of the 

sand filter ranged from 3.2 percent to 28.4 percent. 

$ The following physical and chemical characteristics of the treated water were measured 

at the four influent wells to the AQUABOX 50, the one influent well to the MARABU, 

and the effluent well from the sand filter: pH, sodium, potassium, calcium, iron, 

magnesium, manganese, chloride, floride, nitrite, nitrate, phosphate, sulfate, bicarbonate 

(alkalinity), lead, copper, cadmium, zinc, nickel, chromium, arsenic, and mercury. The 

following trends were noted: 

41 
 

$ Groundwater samples taken from influent sampling well to the AQUABOX 50 located at 

WA3 had the highest sodium, potassium, calcium, iron, manganese, chloride, floride, 

sulfate, and zinc concentrations. 

$ Groundwater samples taken from the influent sampling well to the MARABU located at 

WM1 had the lowest sodium, calcium, magnesium, nitrate, phosphate, and sulfate 

concentrations. 

$ Groundwater samples taken from the effluent sampling well located at WK had the 

lowest iron, manganese, nitrite, phosphate, and zinc concentrations. All of these analytes 

had been significantly reduced most likely due to the precipitation reactions occurring 

within the biological reactive boxes and possibly biological oxidation of nitrite by 

nitrifying bacteria. The highest concentration of nitrate was recorded in samples taken 

from the WK sampling well. 

$ Lead, cadmium, chromium, and mercury concentrations were less than the detection limit 

in all monitoring wells. Copper and nickel concentrations were detected above the 

detection limit in two of the influent wells at low concentrations. Arsenic was detected in 

all monitoring wells at low concentrations. 

$ The initial capital cost of the biological reactor system at the Stadtwerke Duesseldorf AG 

Site, including site preparation, permitting and regulatory costs, construction materials 

and labor, and startup was about 218,700 DM ($113,900 U.S. assuming a 1.92 DM to $1 

U.S. exchange rate). Monitoring and other periodic costs amounted to about 37,000 DM 

($19,300 U.S.) per year. 

3.0 ECONOMIC ANALYSIS 

Cost estimates presented in this section are based on data provided by SWD. Because the cost of 

implementing this technology at a given site depends upon various site-specific factors, costs are initially 

presented below as those directly incurred by SWD in the installation and operation of the biological 

reactor at the Stadtwerke Duesseldorf AG Site in Duesseldorf, Germany. 

The initial capital cost of the biological reactor system at the Stadtwerke Duesseldorf AG Site, including 

site preparation, permitting and regulatory costs, construction materials and labor, and startup was about 

218,700 DM ($113,900 U.S. assuming a 1.92 DM to $1 U.S. exchange rate). Monitoring and other 

periodic costs amounted to about 37,000 DM ($19,300 U.S.) per year. 

42 
The above overall cost estimates are approximate and were provided directly by SWD. Although 

groundwater treatment costs were not independently estimated, the following cost categories (Evans 

1990) should be considered when evaluating the potential cost of treating groundwater using the 

biological reactor system technology: 

C Site preparation 

C Permitting and regulatory requirements 

C Capital equipment 

C Startup 

C Labor 

C Consumables and supplies 

C Utilities 

C Effluent treatment and disposal 

C Residuals and waste shipping and handling 

C Analytical services 

C Maintenance and modifications 

C Demobilization 

Stadtwerke Duesseldorf AG provided the following cost breakdown and explanations in accordance with 

the above listed criteria. 

Site Preparation: The cost for site preparation included the cost for the foundation and construction of 

the workshop hall for the treatment system. 

Permitting and Regulatory Costs: The permitting and regulatory cost included the cost for obtaining the 

license, associated procedures necessary to comply with permitting procedures, and for the design of the 

construction of the treatment system. Both the expert opinion and the quality control of the groundwater 

treatment investigation were requested by the German authorities in order to obtain a permit for 

construction and operation of the biological reactor system. 

Capital Equipment Costs: Capital equipment costs included the rental fees for the two packed biological 

reactors, the MARABU and AQUABOX 50. 

43 
 

Startup Costs: The two largest parts of the startup costs were for the sand filter and for the control 

system of the facility. 

Operating Costs: Operating costs were included the salaries for the project managers and engineers. 

Consumables and Supplies: The cost for consumables and supplies required for this system included the 

cost for replacement parts such as pumps, engines and pipes. The costs for the activated carbon are 

considered in the cost for Aresiduals and waste shipping and handling@. 

Utilities: This cost included the cost for electric power for the system. 

Effluent Treatment and Disposal: No costs were associated with effluent treatment and disposal, since 

this is an in-situ passive treatment technology. 

Residuals and Waste Shipping and Handling: The cost associated with residuals and waste shipping 

included the purchase of the activated carbon and the disposal of the sludge and working materials. 

Analytical Service: The cost for monitoring the performance of the biological reactor system through the 

sampling and analysis of groundwater from influent and effluent monitoring wells included both the 

organic and inorganic analyses for the periodical monitoring of the treatment system. 

Maintenance and Modification: Maintenance and modification costs included the labor costs for 

maintenance of the treatment system. 

Demobilization: Demobilization costs included the demobilization of the foundation and the treatment 

system. 

4.0 TECHNOLOGY APPLICATIONS ANALYSIS 

This section evaluates the general applicability of the biological reactor system technology to 

contaminated waste sites. Information presented in this section is intended to assist decision makers in 

screening specific technologies for a particular cleanup situation. This section presents the advantages, 

disadvantages, and limitations of the technology and discusses factors that have a major impact on the 

performance and cost of the technology. The analysis is based both on the demonstration results and on 

available information from other applications of the technology. 

44 
4.1 FEASIBILITY STUDY EVALUATION CRITERIA 

This section assesses the biological reactor system technology against the nine evaluation criteria used for 

conducting detailed analyses of remedial alternatives in feasibility studies under CERCLA (EPA 1988). 

4.1.1 Overall Protection of Human Health and the Environment 

The biological reactor system technology provides both short-term and long-term protection of human 

health and the environment by reducing the concentrations of contaminants in groundwater. 

BTEX and PAHs are removed by biodegredation and air stripping the extracted groundwater. (Removal 

efficiency is discussed in more detail in Section 2.0.) Treated groundwater from both bioreactors is 

pumped into a storage tank which is aerated to reduce iron concentrations in the treated water. The 

partially treated water flows from the storage tank through a sand filter to remove residual iron. Trapped 

bacteria in the sand filter provide further contaminant biodegradation in the previously treated 

groundwater. The groundwater then filters through an activated carbon unit to remove residual organic 

contamination prior to infiltration back into the aquifer. Exposure from air emissions is minimized 

through the removal of contaminants from the system's air process stream using carbon adsorption units 

before discharge to the atmosphere. 

4.1.2 Compliance with ARARs 

Although general and specific applicable or relevant and appropriate requirements (ARARs) were not 

specifically identified for the biological reactor system technology, compliance with chemical-, location-, 

and action-specific ARARs should be determined on a site-specific basis. While location- and actionspecific ARARs generally can be met, compliance with chemical-specific ARARs depends on the 

efficiency of the biological reactor system in removing contaminants from the groundwater and the sitespecific cleanup level. 

45 
4.1.3 Long-Term Effectiveness and Permanence 

The biological reactor system permanently reduces BTEX and PAH levels in groundwater through 

biodegredation and air stripping. Potential long-term risks to the treatment system workers, the 

community, and the environment from emissions of treated groundwater and discharge of treated 

groundwater are mitigated by ensuring that established standards are met. 

4.1.4 Reduction of Toxicity, Mobility, or Volume through Treatment 

As discussed in Section 4.1.1 and 4.1.3, the biological reactor system offers permanent removal of BTEX 

and PAHs. As such, the toxicity, mobility, and volume of contaminants are also significantly reduced. 

4.1.5 Short-Term Effectiveness 

The permanent removal of BTEX and PAHs from groundwater is achieved relatively quickly, providing 

for short-term effectiveness, as well as long-term effectiveness discussed in Section 4.1.3. Potential 

short-term risks presented during system operation to workers, the community, and the environment 

include air emissions. Exposure from fugitive air emissions during operation, monitoring, and 

maintenance are minimized through the removal of contaminants in the system's air process stream using 

carbon adsorption units before discharge. 

4.1.6 Implementability 

Implementation of the AQUABOX 50 and MARABU biological reactor system involves (1) site 

preparation, (2) system construction and configuration, (3) monitoring and maintenance. Minimal 

adverse impacts to the community and the environment are anticipated during site preparation and system 

installation. 

4.1.7 Cost 

The initial capital cost of the biological reactor system at the Stadtwerke Duesseldorf AG Site, including 

site preparation, permitting and regulatory costs, construction materials and labor, and startup was about 

218,700 DM/year ($113,900 U.S./year assuming a 1.92 DM to $1 U.S. exchange rate). Monitoring and 

other periodic costs amounted to about 37,000 DM/year ($19,300 U.S./year). 

46 
4.1.8 State Acceptance 

State acceptance is anticipated because the biological reactor system uses widely accepted processes to 

remove contaminants from groundwater and to treat air emissions. If remediation was conducted as part 

of Resource Conservation and Recovery Act (RCRA) corrective actions, state regulatory agencies require 

that permits be obtained before implementing the system, such as a permit to operate the treatment system 

and an air emissions permit. 

4.1.9 Community Acceptance 

The system's size and space requirements, as well as the principles of operation, may raise concern in 

nearby communities. However, proper management and operational controls coupled with minimal shortterm risks to the community and the permanent removal of contaminants through these processes make 

this technology likely to be accepted by the public. 

4.2 APPLICABLE WASTES 

The biological reactor system technology demonstrated at Duesseldorf, Germany, was designed to 

remove BTEX and PAHs from groundwater. The technology=s applicability to contaminants other than 

BTEX and PAHs was not examined as part of this demonstration. 

4.3 LIMITATIONS OF THE TECHNOLOGY 

The developer claims that high concentrations of contaminated media can be treated by the system. 

However, high concentrations of contaminants may require more than one pass through the system to 

achieve remediation goals. The full range of system applicability was not evaluated as part of this 

demonstration. 

47 
5.0 BIOLOGICAL REACTOR SYSTEM TECHNOLOGY STATUS 

According to SWD AG, the technology can be used for remediation of contaminated groundwater, 

especially those contaminated with volatile and semivolatile organic compounds. There are currently no 

commercially operating systems in the U.S. 

48 
6.0 REFERENCES

American Society for Testing and Materials (ASTM). 1990. Water Content of Soil/Rock/Soil-Aggregate 

Mixtures, D2216. 

Evans, G. 1990. "Estimating Innovative Technology Costs for the SITE Program." Journal of Air and 

Waste Management Assessment. Volume 40, Number 7. July. 

Tetra Tech EM Inc. (TTEMI) 1999. Quality Assurance Project Plan for the Stadtwerke Duesseldorf AG 

AQUABOX 50 and MARABU Packed Biological Reactor System Evaluation at the Stadtwerke 

Duesseldorf AG Site in Duesseldorf, Germany. July 27. 

U.S. Environmental Protection Agency (EPA). 1987. Test Methods for Evaluating Solid Waste, Volumes 

IA-IC: Laboratory Manual, Physical/Chemical Methods; and Volume II: Field Manual, 

Physical/Chemical Methods, SW-846, Third Edition, (revision 0), Office of Solid Waste and 

Emergency Response, Washington, D.C. 

EPA. 1988. "Guidance for Conducting Remedial Investigations and Feasibility Studies under 

CERCLA." EPA/540/G-89/004. October. 

49