United States
Environmental Protection
Agency
Air And Radiation
(6601J)
EPA 402-R-97-006
July 1997
Mixed Was
Groundw
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United States Air and Radiation EPA 402-R-97-006
Environmental Protection Agency (6601J) July 1997
RESOURCE GUIDE FOR ELECTROKINETICS LABORATORY AND
FIELD PROCESSES APPLICABLE TO RADIOACTIVE AND
HAZARDOUS MIXED WASTES IN SOIL AND GROUNDWATER FROM
1992 TO 1997
September 30,1997
Prepared/or:
U.S. Environmental Protection Agency
Office of Radiation and Indoor Air
Radiation Protection Division
Center for Remediation Technology and Tools
Washington, DC
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Disclaimer
Although this document has been published by the U.S. Environmental Protection Agency, it does
not necessarily reflect the views of the Agency, and no official endorsement should be inferred.
Mention of trade names or commercial products does not constitute endorsements or
recommendation for use.
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Preface
A goal of the Environmental Protection Agency/Office of Radiation and Indoor Air/Center for
Remediation Technology and Tools (EPA/ORIA/CRTT) is to bring innovative remediation
technologies for radioactive and hazardous mixed wastes to the Office of Air and Radiation. This
involves investigating any techniques which show promise in meeting EPA cleanup standards for
hazardous waste in soil and groundwater. The electrokinetic remediation technology utilizes electric
currents to extract radionuclides, heavy metals, organics and hazardous mixed waste from a porous
medium. This resource document compiles a list of all electrokinetic processes used on a patented,
bench, pilot, field or conceptual scale from the period 1992 to 1997. It is intended to be used by
anyone interested in learning about the work that has occurred in the field of electrokinetics or by
environmental management and scientists responsible for identifying and selecting a remediation tool
for use at sites containing radioactive materials.
The information obtained in this report, adheres to the approved Data Quality Objectives (DQO) and
Quality Assurance Program Plan (QAPP) for this document. The information was obtained by the
use of the Internet, other documents, and by information received from various facilities upon request.
This report tried to be consistent in the information cited for each electrokinetic process. However,
this depended upon the availability of information. Therefore, some electrokinetic processes may
appear to be more descriptive than others. If more in-depth information (e.g. biodegradation effects,
hydraulic conditions, transport, sorption, precipitation and dissolution reactions) is desired for a
particular electrokinetic process, then it is advised to contact the facility directly.
This project is coordinated by the EPA/Office of Radiation and Indoor Air (EPA/ORIA). The
principal authors are Barrett Riordan and Rohit Karamchandani from Jack Faucett Associates, Inc.
EPA/ORIA acknowledges all reviewers for their valuable observations and comments.
Questions and comments can be addressed to:
Robin Anderson/Project Manager
EPA/Office of Radiation and Indoor Air
401 M Street, SW (6603 J)
Washington, DC 20460
(202) 233-9385
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TABLE OF CONTENTS
Section Page
Table of Contents ii
List of Tables iii
List of Figures iv
Introduction and Summary 1
Category A: Electrokinetic processes which are currently in use as remediation tools, either in
the United States or in other countries 6
Category B: Electrokinetic processes which are in the experimental testing stage at bench, pilot,
or field scale 29
Category C: Electrokinetic processes which are currently in the conceptual development
stage 73
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LIST OF TABLES
Page
Table 1 Overview of in situ technologies for remediation of soils 5
Table 2 Category A Summary Table 7
Table 3 Effectiveness of electrokinetic treatment of gasoline in clay-composed soil .... 15
Table 4 Summary of Geokinetics International, Inc.'s various completed and ongoing
remediation projects 22
Table 5 Category B Summary Table 30
Table 6 Successfully completed or ongoing electrokinetic remediation projects carried
out by Lynntech, Inc. since 1993 58
Table 7 Category C Summary Table 74
in
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LIST OF FIGURES
Page
Figure 1 Schematic diagram of a typical electrokinetic processing system 2
Figure 2 Lead concentration profile after 123 days of processing kaolinite sand mixture
spiked at 5,322 mg/kg 11
Figure 3 Confirmatory sampling location 14
Figure 4 Diagrammatic overview of the Pool Process 19
Figure 5 Detail of electrode wells 20
Figure 6 Lagoon based remediation of dredgings 20
Figure 7 Electrodes in place before power is applied 21
Figure 8 After remediation, electrodes removed 21
Figure 9 ELECTROSORB™ Cell 25
Figure 10 Installation of ELECTROSORB™ Cell 26
Figure 11 Isotron Electrode Array at Old TNX Basin 28
Figure 12 Example of an application for uranium decontamination using ELECTROSORB™
cylinders 28
Figure 13 Major contributions of the participating Consortium members 36
Figure 14 Layered horizontal and vertical configuration of the electrodes and degradation
zones 37
Figure 15 Metals removal at cathode 42
Figure 16 Site map of DP-25 Sump Area 47
Figure 17 Site map of Area 27 48
Figure 18 General arrangement of a demonstration using SEEC™ Pad technology 51
Figure 19 Contaminant transport processes induced by applying direct current between
buried electrodes 52
Figure 20 Lynntech's Electrokinetic Field Technology 57
Figure 21 Lynntech's Electrokinetic Field Technology 57
Figure 22 Schematic of a field installation for in situ remediation by electro-osmotic
purging 63
Figure 23 2-D multielectrode system 63
Figure 24 Electrokinetic demonstration for chromate removal at the Unlined Chromate Acid
Pit 66
Figure 25 Aerial photo of electrokinetic site over the Unlined Chromic Acid Pit 67
Figure 26 Electrode array configuration for electrokinetic remediation of the Unlined
Chromic Acid Pit 68
Figure 27 Electrokinetic remediation schematic 69
Figure 28 Electrode effluent containing chromate contamination 70
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INTRODUCTION AND SUMMARY
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The theory of applying electric current to the soil or groundwater for remediation of inorganic,
organic, radioactive and heavy metal wastes is called electrokinetic remediation. It is also known as
electroreclamation, electrokinetic soil processing and electrochemical decontamination. Figure 1
depicts a general illustration of an electrokinetic system.
Figure 1: Schematic diagram of a typical electrokinetic processing system (Source: Electro
Remediation Group, Ltd. and Lockheed Missiles and Space Co., Inc., Electrochemical
Remediation of Contaminated Soil: A Technology Overview. 1993)
This figure shows a series of electrodes placed in the contaminated area. A small direct current (50-
150 volts) is then applied between the electrodes. Because of the charge on soil, water and the
contaminate, migration will occur towards the oppositely charged electrodes. In general, active
electrodes in water cause an acid front at the anode and a base front at the cathode. The pH will drop
at the anode and increase at the cathode. To prevent this pH imbalance, the electrodes are placed
inside ceramic casings which are filled with a processing fluid. This processing fluid (also called
surfactants and chelators) not only keeps a balance of pH at the anode and cathode, if chosen
correctly, it also helps solubilize and move contaminants. Some processing fluids which have been
used or considered are acetic acids, humic or gallic acids. The contaminant and processing fluid are
then taken through a pump and recycling purification system where the contaminate is removed and
the processing fluid is reused in the electrokinetic system.
There are five basic phenomena which together make up electrokinetic remediation. All have their
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own properties and influences on the system but together work harmoniously to successfully
remediate a contaminated area. They are diffusion, electrolysis, eletroosmosis, eletrophoresis and
electromigration. If the area of interest is considered to be undisturbed before the electric current is
applied, then the moment electricity enters the system diffusion begins. Diffusion is the process of
redistributing the matter which lies between the electrodes. Electroosmosis is the movement of water
under the electric field. This transport mechanism is necessary for contaminates to move towards
electrode. The more saturated the soil, the easier electroosmois will occur. Electrophoresis and
electromigration are the movement of soil particles and contaminates respectively under an electric
field. Because of the negative charge on soils, electrophoresis will be towards the anode.
Depending upon the charge of the contaminate, electromigration can cause contaminate attraction
towards either the anode or the cathode. Electrolysis is the chemical reaction which occurs around
the electrodes. It can be properly manipulated with the appropriate chemical processing fluid as
previously described.
The concept of electrokinetic remediation has been theorized in the form of electroomosis since the
early 1800s. However, application of electrokinetic remediation to a contaminated area is a fairly
innovative technology dating back to the early 1970s in the United States and in Europe. In the
United States, the approach was led by engineering and civil engineering laboratories and academic
institutions. Technologically, the goal was to use electroosmosis to drive a flushing fluid between
opposing anodes and cathodes. U.S. development work was boosted by an Oregon meeting in 1986
called by the U. S. Environmental Protection Agency (EPA). European researchers, however, focused
on an entirely different approach. They used electromigration to desorb and then migrate anions and
cations to their respective electrodes. Unlike the U.S. focus, much of the early European work was
undertaken by electrochemical researchers. The techniques which resulted showed this difference in
perspective.1
Some contaminates that have been tested with electrokinetic remediation have been uranyl, thorium,
radium, lead, cadmium, mercury, zinc, iron, magnesium, phenol, and BTEX compound (benzene,
toluene and ethylene). Electrokinetic remediation rivals innovative and standard technologies (like
soil excavation, incineration, vitrification, chemical stripping, phytoremediation, pressure flushing,
soil washing, solidification/stabilization, chemical oxidation, air-stripping and impoundment) because
of its efficacy of removal and its in situ and/or ex situ use. However, a limitation to this process is
that the contaminate needs to be solubilize either by an acid front or by a processing fluid in order for
the contaminate to be extracted. Table 1 provides an overview of the key factors for some of these
technologies including electrokinetics.
This document attempted to list and describe all published work on electrokinetic remediation from
1992 to 1997. This work includes electrokinetic remediation being used commercially or on a bench,
pilot, field or conceptual scale. There are three categories in this resource guide. The first category,
Category A, lists all electrokinetic processes that are used as the remediation tool at a contaminated
Geokinetics, International, Inc., Electrokinetic Remediation of Toxic Metals: Statement of Qualifications , June
1997.
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site. Category B lists all electrokinetic processes that are being used on the bench, pilot or field scale.
Finally, Category C lists all electrokinetic process that are in the conceptual development stage.
Electrokinetic remediation being used abroad was also included in this resource guide. Information
about each electrokinetic system includes the developers' name and address, technical description,
status, cost and illustration (if available). This document should be used as a resource guide to
understanding what work has been done in electrokinetic remediation as it applies to radioactive and
hazardous mixed wastes so further research in this area can progress.
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Table 1
Overview of in situ technologies for remediation of soils (Source: U.S. Environmental Protection
Agency, Office of Solid Waste and Emergency Response, In Situ Remediation Technology:
Electrokinetics. EPA542-K-94-007, April 1995)
TECHNOLOGY
Evaluation
Factor
Status
Range of
Metals Treated
Major Limiting
Factor(s)
Site-Specific
Considerations
Electrokinetics
Full-scale applications
in Europe
Recently licensed in
the United States
Broad
State-of-the-art
Moisture level of soil
Homogeneity of soil
Phytoremeditaion
Pilot-scale
Currently being
field-tested in the
United States and
Europe
Broad
State-of-the-art
Longer time required
for treatment
Crop yields and
growth patterns
Depth of
contamination
Concentration of
contamination
Soil Flushing
Commercial
Selected at a
number of
Superfund sites
Limited to
inorganics
(including
radioactive
contaminants)
Potential
contamination of
the aquifer from
residual flushing
solution
Permeability of
soil
Groundwater flow
and depth
Solidification/
Stabilization
Commercial
Broad
Concern with long-
term integrity
Debris
Depth of
contamination
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CATEGORY A
Electrokinetic processes which are currently in use as remediation tools, either
in the United States or in other countries
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Table 2
Category A Summary Table
Name of
developer(s)
Electrokinetics,
Inc. (EK) —
CADEX™
electrode system
Environmental &
Technology
Services (ETS)
Isotron
Corporation —
ELECTROSORB™
Process
Soil
type(s)
tested
kaolinite
clay-
composed
mixture
of sand
and
kaolinite
Distance
between
electrodes
not
available
not
available
not
available
Depth the
electrodes
were
placed in
3 feet
not
available
not
available
Voltage
and/or
DC
current
level
not
available
10-15
amperes
not
available
Processing
fluid(s)
proprietary
conditionin
g agents
not
available
not
available
Size of
remediation
area
30 feet by 60
feet
Depth of 3
feet
200 feet by
200 feet
Depth of 70
feet
not available
Contaminant(s)
treated
lead
volatile organic
compounds
(VOCs), BTEX
(benzene,
toluene,
ethylbenzene,
xylene)
compounds,
total petroleum
hydrocarbons
(TPH)
uranium,
mercury
Time to
complete
cleanup
6-8 months
3-12
months
not
available
Contaminant
concentration
levels before and
after remediation
Before
1,000-5,000 ppm
After
not available
Before
VOC: 10-30 ppm
BTEX: 100-2,200
ppm
TPH: 3,000 ppm
After
VOC: < 0.1 ppm
BTEX: < 40 ppm
TPH: < 35 ppm
Before
mercury: 10-20
ppm
After
uranium: 50%-99%
removal
Treatment
cost
not
available
$17-$50
per ton
not
available
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Table 2 (continued)
Category A Summary Table
Name of
developer(s)
Geokinetics
International, Inc.
(Gil) — Pool
Process
Soil
type(s)
tested
clay
Distance
between
electrodes
5-10 feet
Depth the
electrodes
were
placed in
0.3-3.3 feet
Voltage
and/or
DC
current
level
5-20
volts
0.5-1.0
amperes
Processing
fluid(s)
acid or alkali
Size of
remediation
area
230 feet by
10 feet
Depth of 3. 3
feet
Contaminant(s)
treated
arsenic,
cadmium,
chromium,
copper, lead,
nickel, zinc
Time to
complete
cleanup
2-18
months
Contaminant
concentration
levels before
and after
remediation
Before
Cd: 660 ppm
Cu: 500-1,000
ppm
Ni: 860 ppm
Pb: 300-5,000
ppm
Zn: 2,600 ppm
After
Cd: < 50 ppm
Cu: < 250 ppm
Ni: « 80 ppm
Pb: < 75 ppm
Zn: < 300 ppm
Treatment
cost
$300-$500*
per cubic
yard
*total cost
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41
Research: CADEX™ electrode system2
Developer(s): Electrokinetics, Inc. (EK)
Contact(s): Dr. Robert Gale or Elif Ozsu-Acar
Electrokinetics, Inc.
11552 Cedar Park Avenue
Baton Rouge, LA 70809
Phone: (504) 753-8004
Fax: (504) 753-0028
Research Description
The project investigated the feasibility of removing lead from the soils (approximately 5,400 mg/kg)
in situ at Firing Range 24A located in Fort Polk, Louisiana (see Figure 2). Bullets from the firing
operations disintegrated due to various environmental factors and resulted in the contamination of
the soil. The site remediation project is being conducted for the U.S. Army Engineer Waterways
Experiment Station (USAEWES), Vicksburg, Mississippi, and operated under the U.S.
Environmental Protection Agency's (EPA) Superfund Innovative Technology Evaluation (SITE)
Program. At the time of its initiation, this project represented the first comprehensive study in the
United States of the electrokinetic separation technology applied to in situ remediation of heavy
metals.
The principal compound for removal is lead which has accumulated at the site over a 30-year period.
The remediation site size is 30 feet by 60 feet and the soils are to be remediated to a depth of 3 feet.
The CADEX™ electrode system is being used to remediate the site. This electrode system controls
the chemistry at the cathode and enhances the removal of metal species. The CADEX™ electrode
Information provided was obtained from the following journals and reports:
Acar, Y.B. and Alshawabkeh, A.N., Principles of Electrokinetic Remediation, Environmental Science and Technology ,
Vol. 27, No. 13, pp. 2638-2647 (1993)
Acar, Y.B., Gale R., Marks R.E., and Ugaz, A., Feasibility of Removing Uranium, Thorium, and Radium from Kalonite
by Electrochemical Soil Processing, U.S. Environmental Protection Agency , No. 009-292, Electrokinetics, Inc.,
LA (1992)
Electrokinetics, Inc., Technologies for Waste Management: Report on Project Descriptions
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
10
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system contains proprietary conditioning agents and a depolarizer that significantly reduces the input
power cost and needs only minimum maintenance during processing.
Status
In 1995, pilot-scale studies with 1.5 ton samples of a soil retrieved from the Army firing range and
contaminated with lead leached from bullets were conducted. As of June 1996, electrokinetic
remediation at the demonstration site was operated on a remote basis from a central control house
located at the site where DC input current, DC voltage, site resistivity, and pH can be measured. The
demonstration site goal was to remove as much lead as possible from the soils between June and the
end of 1996. For detail information on this project, please contact: Mr. Mark Bricka, Site Manager,
Waterway Experiment Station, 3909 Halls Ferry Road, Vicksburg, MS 39180. Phone: (601)
634-3700.
11
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%
\
\
Figure 2
Lead concentration profile after 123 days of processing kaolinite sand mixture spiked at 5,322
mg/kg. (Source: Electrokinetics, Inc., Technologies for Waste Management: Report on Project
Descriptions)
12
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A2
Research: Electrokinetic Enhancement3
Developer(s): Environmental & Technology Services (ETS)
Contact(s): Dr. Walter W. Loo
Environmental & Technology Services
2081 15th Street
San Francisco, CA 94114
Telephone: (415) 861-0810
Fax: (415) 861-3269
Research Description
Research and case closure was completed in 1991 at a site in Anaheim, California. The case involved
remediation of 150,000 tons of soil contaminated with chlorinated solvents. The volatile organic
compounds (VOCs) plume covered a 200 feet by 200 feet surface area. An electrokinetic electrode
system involving electro-osmosis desorption of chlorinated VOCs from a 10-foot thick wet clay-
composed layer was installed. Remediation of VOCs to less than 0.1 ppm was achieved.
Remediation cost was at about $17 per ton. The closure was approved by the Santa Ana Regional
Water Quality Control Board and the Orange County Health Services in August 1991.
Another project conducted by ETS involved electrokinetic enhanced in-situ bioventing of gasoline
and BTEX (benzene, ethylbenzene, toluene, xylene)-contamination in soil. The gasoline in soil was
related to a 10,000-gallon underground storage tank spill in San Diego, California. The gasoline soil
plume covered an area of about 2,400 square feet and to a depth of 30 feet with gasoline
concentration ranging from 100 to 2,200 ppm. Direct current was applied through 56 electrodes
installed in the upper clay layer to move the contaminants and water down 15 feet into dense
cemented conglomerate sandstone where contaminants were removed by bioventing. Electrolysis of
some water molecules, resulting from the electrical gradient, was thought to have produced hydroxyl
ions that promoted oxidation of the contaminants. Total petroleum hydrocarbons (TPH) and BTEX
were treated to non-detect in about 8 hours. The soil remediation effort was completed after about
90 days of treatment. The concentration of gasoline in soil after treatment was less than 40 ppm. The
Information provided was obtained from the following reports:
Loo, W.W. and Chilingar, G.V., Advances in the Electrokinetic Treatment of Hazardous Wastes in Soil and
Groundwater, presented at HAZMACON 97, Santa Clara, California, pp. 1-15 (1997)
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
13
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cost of treatment was about $50 per ton for this advanced soil treatment process which provides a
cost effective solution to this soil plume.
Another remediation effort in 1994 involved the removal of a 1,000-gallon underground storage tank
located at a warehouse and distribution facility in Los Angeles (see Figure 3). The volume of the
gasoline soil plume was estimated to be about 3,300 cubic yards and the TPH concentrations were
as high as 23,000 ppm, with an average level of 3,000 ppm. The remedial system that was used
included a heat enhanced bioventing system, an ultraviolet light disinfection system, granular activated
carbon adsorption, and electrokinetic treatment which was designed to remediate the lower 5 feet,
35 to 40 feet below the surface grade, of low permeability clay-composed silts. The electrokinetic
system was connected to direct current (DC) power supply. The system was operated at about 10
to 15 amperes of electricity flow to 'dry out' the clay-composed silts in the bottom 5 feet. After
approximately 12 months, samples taken from the site indicated that the concentration of TPH as
gasoline in soil after treatment was below 35 ppm. The effectiveness of the electrokinetics treatment
of the clay-composed soil located at the 40-foot depth is given in Table 3.
Status
ETS is continuing to conduct research and remediation activities involving electrokinetic treatment
of hazardous and toxic waste in soil and groundwater. Several state-of-the-art remedial technologies
are being invented and implemented for use by Dr. Loo and ETS.
14
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Figure 3
Confirmatory sampling location (Source: Loo, W.W. and Chilingar, G.V., Advances in the Electrokinetic Treatment of Hazardous
Waste in Soil and Groundwater. presented atHAZMACON 97, Santa Clara, California, pp. 1-15, 1997)
15
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Table 3
Effectiveness of electrokinetic treatment of gasoline in clay-composed soil
(Source: Loo, W.W. and Chilingar, G.V., Advances in the Electrokinetic Treatment of Hazardous Waste in Soil and Groundwaten
presented atHAZMACON97, Santa Clara, California, pp. 1-15, 1997)
(All units are in mg/kg or ppm)
Benzene
Toluene
Ethylbenzene
Xylene
Benzene
Toluene
Ethylbenzene
Xylene
C-l Area
18
0.45
1.6
0.15
1.2
2.9
0.17
0.6
0.03
0.54
C-2 Area
C-5 Area
1300
87
0.68
0.28
27
2.7
23
1.4
140
0.66
1.7
No data
0.07
0.18
0.43
0.06
0.04
No data
0.51
16
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A3
Research: Electrokinetic Remediation4
Developer(s): Geokinetics International, Inc. (Gil)
Contact(s): Dr. Stephen R. Clarke
Gil
829 Heinz Street
Berkeley, CA 94710
Telephone: (510) 704-2940
Fax: (510)848-1581
E-mail: EDASteve@aol.com
Research Description
Gil primarily uses an electrokinetic technology called the "Pool Process" (also called "closed loop
process") to remediate toxic heavy metals such as arsenic, chromium, nickel, copper, zinc, lead, and
cadmium (see Figure 4). The major components of the Pool Process are as follows:
• ion-permeable electrolyte casings are placed in the contaminated media and connected
to a centralized electrochemical ion-exchange (EIX) based electrolyte management
system. Each casing has an electrode inside. Together, these form alternating rows
of anodes and cathodes. Electrolyte is circulated in a closed loop between the
electrode casings and the EIX units;
• electrolysis of water in the electrolyte results in the formation of H+ ions at the
anodes and OH- at the cathodes. These ions migrate through the casing into the soil
generating a temporary and localized pH shift which desorbs contaminating ions;
Information provided was obtained from the Internet at the Geokinetics International, Inc. world wide web site
at http:\\www.geokinetics.com and the following reports:
Geokinetics, International, Inc., Electrokinetic Remediation of Toxic Metals: Statement of Qualifications , June 1997
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
17
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• once desorbed, the contaminating ions migrate under the influence of the applied
potential (electromigration) to their respective electrodes (anodes for anions, cathodes
for cations). Here they pass through the electrode casing walls and are taken up by
the circulating electrolytes. The pH at the anode and cathode is managed by the
addition of acid or alkali as required;
• contamination is selectively recovered from the circulating electrolytes as they pass
through the EIX units. Soluble but benign elements are returned to the soil to
maintain soil properties;
• periodically the EIX units are regenerated by polarity reversal. This recovers the
contaminants in a concentrated, pure and re-usable form.
Figure 5 shows some of the detail of the electrode wells. Figures 6, 7 and 8 show an example of an
actual electrokinetic remediation of a lagoon of dredgings. GIFs electrokinetic process can be
operated in three separate ways:
1) In situ remediation: electrode wells are placed directly in the ground and contamination is
recovered with the slightest disturbance to the site.
2) Batch operation: contaminated media is transported to a batch facility and treated ex situ.
Batch times take between 1 to 5 days depending on electrode spacing and current loading.
3) Electrokinetic Ring Fence (EKRF): this uses a chain of electrode pairs deployed in the ground
to recover ionic contamination from groundwater as it flows past the electrodes. It is
significantly more efficient than pump and treat and is sludge free.
The first ever commercial application of electrokinetics was conducted in a former paint factory,
'Oeverbosch' in Groningen, the Netherlands, by Gil in 1987. The 400-cubic yard site was
contaminated with 20,000 ppm of lead and 12,000 ppm of copper. A vertically installed array of
alternating anodes and cathodes (each consisting of an electrode placed inside a semipermeable well
casing) was spaced on 10-feet intervals. Anodes and cathodes were each connected to separate
anolyte and catholyte management systems. Anolyte and catholyte pH was managed by the addition
of acid or alkali as required. The recirculating electrolytes were periodically treated to remove
collected contaminants and other ions. After 43 0 hours of operation, lead concentrations ranged from
90 to 700 ppm with an average reduction of 70 percent, while copper concentrations ranged from 15
to 250 ppm with an average reduction of 80 percent.
18
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Another remediation project involving electrokinetics processing was conducted by Gil during 1992.
The proj ect was performed at Woensdrecht on behalf of the Dutch ministry of defense. The work
was undertaken at a former Dutch Royal Air Force base. The 3400-cubic yard site was contaminated
with cadmium and other toxic heavy metals. Aircraft wash-down operations and plating shop
activities were the main reasons for the contamination. The recovered material was placed in a
temporary lagoon and treated in two large onsite batches. Large horizontal tubular cathodes and
short vertical anodes were used. The cathodes were placed at 5-feet intervals at the bottom of the
lagoon prior to it being filled with contaminated soil. The tubular anodes were placed at 5-feet
intervals between the cathodes after the lagoon was filled. The electrokinetic process reduced
cadmium concentrations from 7,300 ppm to 47 ppm in 580 days. All other toxic metal concentrations
were also reduced significantly. This project is considered to be the largest electrokinetic project
completed worldwide.
Status
Gil continues to perform several remediation projects involving electrokinetics both in the United
States and abroad. The commercial scale electrokinetic remediation technology used by Gil is mainly
used for the extraction of toxic metals and toxic anions from soil and groundwater. Table 4
summarizes GIFs various completed and ongoing remediation projects.
19
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Figure 4
Diagrammatic overview of the Pool Process (Source: Geokinetics, International, Inc.,
Electrokinetic Remediation of Toxic Metals: Statement of Qualifications. June 1997)
20
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per
•.cable ~\
__ Lknliohh; fed & i-ciurn
Figure 5
Detail of a general electrode well (Source: Geokinetics, International, Inc.. Electrokinetic
Remediation of Toxic Metals: Statement of Qualifications. June 1997)
Figure 6
Lagoon based remediation of dredgings (Source: Geokinetics, International, Inc., Electrokinetic
Remediation of Toxic Metals: Statement of Qualifications. June 1997)
21
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Figure 7
Electrodes in place before power is applied (Source: Geokinetics, International, Inc.,
Electrokinetic Remediation of Toxic Metals: Statement of Qualifications. June 1997)
Figure 8
After remediation, electrodes removed (Source: Geokinetics, International, Inc., Electrokinetic
Remediation of Toxic Metals: Statement of Qualifications. June 1997)
Table 4
22
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Summary of Geokinetics International, Inc.'s various completed and ongoing remediation
projects (Source: Geokinetics International, Inc., Electrokinetic Remediation of Toxic Metals:
Statement of Qualifications. June 1997)
Year
1997-
ongoing
1997-
ongoing
1997-
ongoing
1997-
ongoing
1997
1996
1996
1996
1992 - 1994
Location
California
Virginia
Pearl Harbor -
Oahu, HI
Alameda Naval
Air Station
California
California
California
California
Temporary
Landfill at the
airbase of
Woensdrecht
Client
Large International
Chemicals Corporation
Large US Engineering &
Chemicals Corporation
US Navy & EPA Office of
Technology Development
US Navy & EPA Office of
Technology Development
Large international water
services company
EPA Region 6, Office of
Emergency Response
Large US Industrial &
Communications Company
EPRI & SoCal Eddison
Ministry of Defence/DGWT
Description
Pilot test of the recovery of Zn
from 80,000 yd3 chemical
sludge ponds
Large pilot scale evaluation of
Zn recovery from 200,000 yd3
chemical sludge ponds
In situ remediation of Pb from
battery re-processing plant
(1,500 yd3)
Pilot scale (40 yd3) recovery of
Cr from former plating
operations
Bench scale evaluation of Pb
recovery from former battery
plant
Bench scale evaluation of Zn
recovery from mine tailings
Bench scale recovery of Cr from
former plating shop
Large bench scale study and
conceptual design of Pb from
battery manufacturing site
Form on site lagoon and in situ
remediation of 3,400 yd3 sludge
contaminated with Cr, Ni, Cu,
Zn and Cd
Cost
Ongoing
Ongoing
Ongoing
Ongoing
$42,000
$45,000
$16,000
$75,000
$1,040,000
23
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Table 4 (continued)
Summary of Geokinetics International, Inc.'s various completed and ongoing remediation
projects (Source: Geokinetics International, Inc., Electrokinetic Remediation of Toxic Metals:
Statement of Qualifications. June 1997)
Year
1990 - 1992
1989
1988
1987
Location
Temporary Landfill
"Vleddermond" at
Stadskanaal
Former wood
impregnation plant
"PERDOK"
Loppersum
Galvanizing plant
"Braat" at Deflt
Former paint factory
"Oeverbosch" at
Groningen
Client
Municipality of
Stadskanaal/Province
of Groningen
Kwint
b.v./Municipality of
Loppersum
Bammensgroep,
Maarssen
Province of Groningen
Description
Establish temporary landfill
and in situ remediation of
2,500 yd3 soil and sludges
from gardens and canals at
Stadskanaal contaminated
withCd
In situ 300 yd3 clay polluted
with heavy metals Ar and
Cu
In situ 300 yd3 clay polluted
with heavy metals Zn and
Cd
In situ 400 yd3 clay polluted
with heavy metals Cu, Pb
andZn
Cost
$960,000
$160,000
$160,000
$120,000
24
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A4
Research: Electrokinetic Remediation5
Developer(s): Isotron Corporation
Contact(s): Henry Lomasney
Isotron Corporation
13152 Chef Menteur Hwy
New Orleans, LA 70129
Telephone: (504) 254-4624
Fax: (504)254-5172
Research Description
Electrokinetics was used in situ in 1994 in the Old TNX Basin at the Savannah River Site in South
Carolina to remediate mercuric nitrate contamination in unsaturated soil consisting primarily of sand
and kaolinite. The ongoing project is supported by the U.S. Department of Energy's (DOE) Office
of Technology Development. An ELECTROSORB™ process with a patented cylinder (see Figures
9 and 10) to control buffering conditions in situ and an iron exchange polymer matrix called
ISOLOCK™ to trap metal ions were employed.
The electrodes are placed in boreholes in the soil and a direct current is applied (see Figure 11).
Under the influence of the current, ions migrate through the pore water to an electrode, where they
are trapped in the polymer matrix. If desired, the polymer can contain ion exchange resins or other
sorbants that can trap and hold ions before they reach the electrode. When electric current is applied
to the system, electrodes are monitored and periodically replaced with fresh electrode assemblies.
This allows the used assemblies to be chemically treated and analyzed for the presence of mercury
and other metals in the polymers and on the electrodes. The special features of this technology are
Information provided was obtained from the Internet at the Isotron Corporation world wide web site at
http:\\www.isotron.com and the following report:
Isotron Corporation, Electrolytic Migration Technology For Mercury Decontamination of Old TNX Area , Phase 1
Technical Report, Subcontract No. AA89030P, July 1992
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
25
-------
upply
Scaling collar
for clccErode &,
sensor u
Figure 9
ELECTRO SORB™ Cell (Source: Isotron Corporation, Electrolytic Migration Technology For
Mercury Decontamination of Old TNX Area. Phase 1 Technical Report, Subcontract No.
AA89030P, July 1992)
26
-------
Fotyvinyl Chloride
Tubing
LocMug collar KJ
position electrode
cyliadcr at desired
elevadbii
Et£CTROSORB
cylinder
Figure 10
Installation of ELECTRO SORB™ Cell (Source: Isotron Corporation, Electrolytic Migration
Technology For Mercury Decontamination of Old TNX Area. Phase 1 Technical Report,
Subcontract No. AA89030P, July 1992)
27
-------
the polymer matrices that serve as ion traps. These matrices also serve as sources of chemicals that
can regulate pH or that will enhance the efficiency of the process. Preliminary investigations indicated
that mercury concentrations ranging from 10 to 20 ppm were found in the Basin.
Status
After the conclusion of the field demonstration at the Savannah River Site in 1995, the
ELECTROSORB™ technology (see Figure 12) was also successfully used on a Unit 7 mine site in
Uzbekistan to decontaminate a 10,000 meter area contaminated with gamma emitting radionuclides
(uranium). The gamma range was reduced from 50-99 percent in some areas after application of the
technology.
28
-------
r't
Figure 11
Isotron Electrode Array at Old TNX Basin (Source: Isotron Corporation world wide web site at
http: \\www. i sotron. com)
Anode OEmfer
Figure 12
Example of an application for uranium decontamination using ELECTROSORB™ cylinders
(Source: Isotron Corporation world wide web site at httpAWww.isotron.com)
29
-------
CATEGORY B
Electrokinetic processes which are currently in the experimental testing stage
at hpnrh. mint nr fiplH sralp
•/
at bench, pilot or field scale
30
-------
Table 5
Category B Summary Table
Name of
developer(s)
Consortium of
Monsanto, DuPont
and General
Electric —
Lasagna™ Process
Electrokinetics,
Inc. (EK) —
Electro-Klean™
Soil Processing
Soil
type(s)
tested
clay-
composed
with gravel
and sand
layers
saturated/
unsaturate
d sands,
silts, fine-
grained
clay,
sediments
Distance
between
electrodes
2-7 feet
3 feet
Depth the
electrodes
were
placed in
15 feet
3 feet
Voltage
and/or
DC
current
level
100-140
volts
40-45
amperes
450-600
volts
15-20
amperes
Processing
fluid(s)
not available
acetic acid
Size of
remediation
area
15 feet by 10
feet
Depth of 15
feet
Lead
contaminated
site:
10 feet by 34
feet
Depth of 3
feet
Contaminant(s)
treated
TCE
uranium,
thorium, radium,
arsenic, BTEX
compounds,
cadmium,
chromium,
copper, lead,
nickel, phenol,
TCE, zinc
Time to
complete
cleanup
4-36
months
1-6 months
Contaminant
concentration
levels before
and after
remediation
Before
1 ppb to 1760
ppm
After
< 1.5 ppm
Before
uranium:
1,000 pCi/g
thorium: 50-
300 pCi/g
radium: 1,000
pCi/g
lead: 2,000
ppm
After
uranium: 95%
removal
thorium,
radium: not
available
lead: 25%-
50% removal
Treatment
cost
$40-$90 per
cubic yard
$50-$150per
ton
31
-------
Table 5 (continued)
Category B Summary Table
Name of
developer(s)
Electro-Petroleum,
Inc. and Lehigh
University
Soil
type(s)
tested
kaolinite
clay, sand
Distance
between
electrodes
not
available
Depth the
electrodes
were
placed in
not
available
Voltage
and/or
DC
current
level
30 volts
1.5
amperes
Processing
fluid(s)
ethylenedi-
amine
(EDA),
distilled
water
Size of
remediation
area
Laboratory
soil sample
tube 7.62 cm
long and
3.55 cm deep
Contaminant(s)
treated
uranium,
strontium,
cesium,
chromium,
cobalt,
cadmium,
mercury, lead,
nickel, zinc,
hydrocarbons
Time to
complete
cleanup
24-170
hours
Contaminant
concentration
levels before
and after
remediation
Before
U: 10-100 ppm
Sr, Cs: 1,000
ppm
Cr: 3,000 ppm
Hg: 5-130 ppm
Ni: 1,000 ppm
Pb: 15,000 ppm
Zn: 22,500 ppm
After
U: 30%-80%
removal
Sr: 95%-100%
removal
Cs: 70%-90%
removal
Cr: 95%
removal
Hg: 60%-80%
removal
Ni: 94%
removal
Pb: 60%-85%
removal
Zn: 35%-65%
removal
Treatment
cost
$37.5 per
cubic yard
Table 5 (continued)
32
-------
Category B Summary Table
Name of
developer(s)
Isotron
Corporation —
SEEC™ Pad
Technology and
ELECTROSORB™
Process
Lynntech, Inc.
Massachusetts
Institute of
Technology (MIT)
Soil type(s)
tested
sand,
kaolinite
low
permeability
soils (clay)
kaolinite
Distance
between
electrodes
4-5 feet
not
available
20
centimeter
s
Depth the
electrodes
were
placed in
2 feet
not
available
1.5
centimeter
s
Voltage
and/or
DC
current
level
90-100
volts
40-50
amperes
not
available
20 volts
Processing
fluid(s)
citrate and
carbonate
salts
not
available
acetic acid
Size of
remediation
area
8 feet by 9
feet
Depth of 2
feet
not available
Laboratory
sample
cylinder 200-
mm long and
32-mm in
diameter
Contaminant(s)
treated
uranium,
mercury
chromium, lead,
chlorinated
hydrocarbons
zinc, phenol
Time to
complete
cleanup
20-40
days
3-9
months
9-60 days
Contaminant
concentration
levels before
and after
remediation
Before
uranium: 600
ppm
After
uranium: > 99%
removal
Before
not available
After
lead: 65%
removal
Before
40% water +
500 mg/L zinc
60% kaolin clay
phenol: 45-450
ppm
After
zinc: 98%
removal
phenol: 94%
removal
Treatment
cost
$95 per ton
$65-$125 per
cubic yard
$20-$30 per
ton
33
-------
Table 5 (continued)
Category B Summary Table
Name of
developer(s)
Sandia National
Laboratories
(SNL)
Texas A&M
University
Soil type(s)
tested
unsaturated
soils with
25%
saturation
kaolinite,
saturated
silty clay
Distance
between
electrodes
not
available
5 meters
Depth the
electrodes
were
placed in
15 feet
5 meters
Voltage
and/or
DC
current
level
not
available
100 volts
Processing
fluid(s)
sodium
chloride
citric acid,
acetic acid,
disodium
ethylnedi-
aminetetr-
aacetate
(EDTA)
Size of
remediation
area
700 to 1,000
cubic feet
(depth of 15
feet)
50 meters by
100 meters
Depth of 5
meters
Contaminant(s)
treated
uranium,
chromium
copper, lead,
organics
Time to
complete
cleanup
4-12
months
6 months
Contaminant
concentration
levels before
and after
remediation
Before
chromium: 25-
10,000 ppm
After
chromium:
75%-90%
removal
Pb: 5,000 ppm
removal
Cu: 10,000 ppm
removal
Treatment
cost
$50-$150per
ton
$3 9 per unit
volume
34
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Bl
Research: Lasagna™ Process6
Developer(s): Consortium consisting of Monsanto, E.I. du Pont de Nemours & Co.
(DuPont), and General Electric (GE)
Contact(s): Dr. Sa Ho
Environmental Services Center
Monsanto Company
St. Louis, MO 63167
Telephone: (314) 694-5179
Fax: (314)694-1531
E-mail: svho@monsanto.com
Research Description
In early 1994, EPA signed a Cooperative and Research and Development Agreement (CRADA) with
a private research Consortium — consisting of Monsanto, DuPont and GE — to jointly develop an
integrated, in situ remedial technology, referred to as the Lasagna™ process. The Consortium's
activities are being facilitated by Clean Sites, Inc., under a Cooperative Agreement with EPA's
Technology Innovation Office. The overall objective of the Consortium is to sufficiently develop the
integrated in situ remediation technology so that it can be utilized for site remediation. Figure 13
shows the major contributions of the participating Consortium members.
The Lasagna™ process remediates soils and soil pore water contaminated with soluble organic
compounds. Lasagna™ is especially suited to sites with low permeability soils where electro-osmosis
can move water faster and more uniformly than hydraulic methods, with very low power
consumption. The process uses electrokinetics to move contaminants in soil pore water into
treatment zones where the contaminants can be captured or decomposed.
Information provided was obtained from the Internet at the Monsanto world wide web site at
http:\\www.monsanto.com and the following report:
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
35
-------
Highly permeable subsurface sorption zones will be created in vertical configuration by hydraulic
fracturing or similar technology followed by the introduction of certain sorbants. The electrodes,
placed vertically on either side of contaminant plume, will flush contaminants by electro-osmotic flow
into sorption zones containing certain sorbants. (The electrodes may be constructed horizontally or
vertically depending on the site and contaminant characteristics.) The layered configuration of the
electrodes and degradation zones is shown in Figure 14. The contaminant targeted in this proposed
program is trichloroethylene (TCE).
The major features of the technology are:
• electrodes energized by direct current, which causes water and soluble contaminants
to move into or through the treatment layers and also heats the soil;
• treatment zones containing reagents that compose the soluble organic contaminants
or adsorb contaminants for immobilization or subsequent removal and disposal; and
• a water management system that recycles the water that accumulates at the cathode
(high pH) back to the anode (low pH) for acid-base neutralization. Alternatively,
electrode polarity can be reversed periodically to reverse electro-osmotic flow and
neutralize pH.
The major limitations to the Lasagna™ process are the following:
• treatment chemistry and procedures need to be developed to ensure compatibility of
the treatment processes for individual contaminants;
• problems in maintaining appropriate electrical contact to electrodes and trapping
gases generated by electrolysis need to be resolved; and
• for field implementation, bioremediation in Lasagna™ treatment zones need to be
further developed.
In early 1995, with significant funding by DOE, the work group initiated a field experiment at the
DOE Paducah Gaseous Diffusion Plant (PGDP) in Kentucky, which has clay-composed soil
contaminated with TCE, to test the vertical configuration of the Lasagna™ process. The PGDP site
consists of a 4-foot layer of gravel and clay overlaying a 40-foot layer of sandy clay loam with
interbedded sand layers. The clay soil had been contaminated with TCE at concentrations ranging
36
-------
Dufont (Anaerobic BIcu
VKrtif.it Zone liiaallation)
DOE (Site SelEdiun aril)
Field Support) C". 4,
Gaieral Etediiii, -„——
(EK an
CPA (Hydrafracturcr
Integrated in-situ
Remediation Technology
Figure 13
Major contributions of the participating Consortium members (Source: Monsanto world wide
web site at http:\\www.monsanto.com)
37
-------
A. Horizontal Configuration
«iPPLU-
POTC
u ai t ectrode
B. Vertical Conflguraticn
Figure 14
Layered horizontal and vertical configuration of the electrodes and degradation zones (Source:
Monsanto world wide web site at httpAWww.monsanto.com)
38
-------
from 1 ppb to 1,760 ppm. The average contamination at the PGDP site was 83.2 ppm. Due to low
organic content, the soil adsorbed very little TCE.
Status
Installation procedures of important elements of the field experiments in the vertical configuration
were conducted in the summer of 1994. CDM Federal Programs Corporation conducted preliminary
field tests, and in November 1994 they installed the field experiment at the DOE PGDP site. The
Phase I-Vertical field test, which operated for 120 days at the site, was successfully completed in May
1995. Soil samples taken throughout the test site before and after the test indicate a 98-percent
removal of TCE, from a tight clay soil. A Phase II-Vertical field experiment was planned at the
Paducah site for 1996. This phase is expected to consist of two stages. In the first stage (Phase Ila-
Vertical), the Lasagna™ process will be used to treat 20 times more soil than Phase I. If successful,
this will be followed by a full-scale first application demonstration encompassing the entire
contaminated region (105 ft x 60 ft x 45-ft deep), with treatment to be completed in 12 to 24 months.
In addition, Phase I-Horizontal field tests in TCE-contaminated soils using the Lasagna™ process,
were to be conducted during the summer and fall of 1996 at sites in Ohio and Nebraska, where
preliminary testing has already been conducted.
The technology implementation cost for Lasagna™ as conducted in the Phase I test (steel plate
electrode with wick drains and carbon-filled treatment zone) is estimated at $80-$90 per cubic yard
for remediation in 1 year, $50-$60 per cubic yard if 3 years are allowed for remediation. Comparable
estimates for the Phase II mode of operation are $60-$70 per cubic yard (1 year) and $40-$50 per
cubic yard (3 years). Deeper contamination, although involving more technically challenging
enhancement, costs less because of the larger volumes remediated per electrode.
39
-------
B2
Research: Electro-Klean™ Electrokinetic Soil Processing7
Developer(s): Electrokinetics, Inc. (EK)
Contact(s): Dr. Robert Gale or Elif Ozsu-Acar
Electrokinetics, Inc.
11552 Cedar Park Avenue
Baton Rouge, LA 70809
Phone: (504) 753-8004
Fax: (504) 753-0028
Research Description
Electro-Klean™ is a process that removes or captures heavy metals, radionuclides, and selected
volatile organic pollutants from saturated or unsaturated sands, silts, fine-grained clays, and
sediments. Electro-Klean™ can be applied in-situ or ex-situ, and uses direct currents with electrodes
placed on each side of the contaminated soil mass. Conditioning fluids may be added or circulated
at the electrodes to enhance the electrochemistry of the process. An acid front migrates towards the
negative electrode (cathode) and contaminants are extracted through electroosmosis and electro-
migration (see Figure 15). The concurrent mobility of the ions and pore fluid decontaminates the soil
mass. Contaminants are electroplated on the electrodes or separated in a post-treatment unit.
Bench scale tests have removed arsenic, benzene, cadmium, chromium, copper, ethylbenzene, lead,
nickel, phenol, trichloroethene, toluene, xylene, and zinc from soils. EPA has initiated the Volume
Information provided was obtained from the following journals and reports:
Acar, Y.B. and Alshawabkeh, A.N., Principles of Electrokinetic Remediation, Environmental Science and Technology,
Vol. 27, No. 13, pp. 2638-2647 (1993)
Acar, Y.B., Gale R., Marks R.E., and Ugaz, A., Feasibility of Removing Uranium, Thorium, and Radium from Kalonite
by Electrochemical Soil Processing, U.S. Environmental Protection Agency , No. 009-292, Electrokinetics, Inc.,
LA (1992)
Electrokinetics, Inc., Technologies for Waste Management: Report on Project Descriptions
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
40
-------
Reduction and Chemical Extraction (VORCE) proj ect to investigate technologies that can reduce the
volume of soil contaminated with radioactivity at Superfund sites. The use of electrokinetics has been
included for investigation as a potential VORCE technology.
There are however some limitations to the technology. Some of the major limitations to the
technology are that: 1) it is less cost-effective in sands and gravels for removal of VOCs as these
compounds are more easily removed by vacuum extraction, bioventing and soil washing techniques;
and 2) complex mixtures of heavy metals, radionuclides and organic pollutants can affect the
electrochemistry and result in loss of removal efficiency.
Bench scale studies under EPA's SITE Program also demonstrated the feasibility of removing
uranium, thorium and radium from kaolinite. Uranium removal tests at 1,000 pCi/g of activity
demonstrated that the process efficiently removed uranium from kaolinite. Removal efficiency
decreased from the anode towards the cathode, due to increase in pH. A yellow uranium hydroxide
precipitate was encountered in sections close to the cathode and on the cathode. Formation of this
precipitate increases the resistivity, the voltage gradients and energy expenditure. Acetic acid
introduction at the cathode successfully prevented the precipitation encountered close to the cathode
and 95% of uranium removal was achieved. Thorium removal tests at 50-300 pCi/g of activity have
demonstrated that thorium is only removed by migration from the leading anode sections of the cell.
Complex species that can reduce the net ionic charge on the thorium species are necessary in order
to efficiently remove thorium by electrokinetics. Radium tests at 1,000 pCi/g of activity have
demonstrated minimal removal across the test cells. The only rational explanation is the extremely
low solubility of the precipitated radium sulfate species. Similar to the tests results for thorium,
complex species are necessary to remove radium.
Status
Theoretical and experimental modeling, bench scale, and pilot scale feasibility studies are routinely
performed in EK laboratories for an assessment of the potential to extract hazardous metals, organics
or radionuclides using in-situ electrokinetic remediation and/or in-situ electrokinetic bioremediation.
A pilot scale laboratory study investigating removal of 2,000//g/g lead loaded into kaolinite was
completed in 1993. Removal efficiencies of 90 to 95 percent were obtained. The electrodes were
placed 3 feet apart in a 2-ton kaolinite specimen for 4 months, at an energy cost of about $ 15 per ton.
The results of a second pilot-scale laboratory study using 5,000 //g/g of lead absorbed on kaolinite
showed similar efficiency results as the earlier study.
41
-------
In 1994, EK developed a mathematical model for multicomponent contaminant transport of reactive
species under an electric field. Three pilot scale tests were conducted using soil specimens weighing
1 ton in each test. The objective of these tests was to investigate the effect of up-scaling bench scale
tests to pilot scale tests. These tests evaluated the feasibility and cost efficiency of electrokinetic soil
remediation at dimensions representing field conditions, and also assessed the hypothesized principles
of multicomponent contaminant transport under an electric field. Pilot scale tests demonstrated up
to 98 percent lead removal from soils. Also in 1994, EK, in collaboration with a Norwegian firm,
conducted bench scale tests on samples retrieved from a site in Heimdal, Norway, to assess the
efficiency of removing chromium and to evaluate the efficiency of two different techniques proposed
for enhancement. These tests were run for about 1200 to 1400 hours and, as a result, 68 percent of
the initial chromium present in the soil was removed. A pilot scale testing study in collaboration with
the Norwegian firm is currently in the planning stages.
42
-------
Figure 15
Metals removal at cathode (Source: Acar, Y.B. and Alshawabkeh, A.N., Principles of
Electrokinetic Remediation. Environmental Science and Technology. Vol. 27, No. 13, pp. 2638-
2647, 1993)
43
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B3
Research: In Situ Electrokinetic Soil Processing8
Developer(s): Electro-Petroleum, Inc. and Lehigh University
Contact(s): Dr. J. Kenneth Wittle
Electro-Petroleum, Inc.
Suite 1118
996 Old Eagle School Road
Wayne, PA 19087
Telephone: (610) 687-9070
Fax: (610) 964-8570
Research Description
Most of the research for the In Situ Electrokinetic Soil Processing has been conducted under two
contracts through the Argonne and Sandia National Laboratories. Studies in the laboratory were
conducted jointly by Electro-Petroleum, Inc. and Lehigh University. The research was composed of
two phases of laboratory work.
In the first phase, short-term tests were carried out on the samples. The contaminant levels selected
in the experiments were typical of levels to be found at various DOE sites. The laboratory
experiments have shown mobilization of 11 heavy metals and 6 organic compounds in 5 soil matrices.
The degree of success of decontamination seemed to be parameter specific and is more dependant
on the type of contaminant to be removed than the type of medium being decontaminated.
Researchers determined that this electrokinetic process can treat soils, sludges, and sediments
Information provided was obtained from the following journals and reports:
Wittle, J.K. andPamukcu, S., Electrokinetic Treatment of Contaminated Soils, Sludges, and Lagoons. Final Report,
DOE/CH-9206, U.S. Department of Energy, Argonne National Laboratory, (1993)
Wittle, J.K. andPamukcu, S., Electrokinetically Enhanced In-situ Soil Decontamination, in Wise and Trantolo (eds.)
Remediation of Hazardous Waste Contaminated Soils, Chapter 13, New York: Marcel Dekker, pp. 245-298
(1993)
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
44
-------
contaminated with heavy metals (cadmium, mercury, lead, nickel, zinc), volatile and semi-VOCs,
solvents, BTEX compounds, surrogate radionuclides (cobalt, cesium, strontium, uranium) and
inorganic cyanides. It was determined, however, that the process works best on clay-composed soils
with low hydraulic permeability. Electrokinetic permeabilities for aqueous systems in clays have been
demonstrated to be up to one thousand times greater than normal hydraulic permeabilities, and some
heavy metals have exhibited removal efficiencies of up to 100 percent.
The second phase of work involved development of a model of contaminant transport in soils.
Testing of removal of soil contaminated with strontium and acetic acid was carried out. The model
predicted a slower rate of removal of strontium and a faster rate of removal for acetic acid than what
the laboratory tests demonstrated. In all the electrokinetics experiments, a constant 30-volts DC
potential was applied across the electrodes. The actual voltage gradient in soil varied in time and
space and also with type of soil contamination pair.
Status
The laboratory experiments demonstrated the capability to mobilize ionic and non-ionic contaminants
through various types of soil. The experiments also indicated that electrokinetics process has the
potential to solve soil remediation problems under a broad range of real site conditions. The process
can work well together with a surfactant flush, pump and treat system. Although reductions of up
to 100 percent have been demonstrated in the laboratory, field testing and treatability studies on site-
specific soil samples using electrokinetics processes are still under development.
A cost evaluation based on laboratory results and previous in-field investigations provided the basis
for estimating the treatment costs. For a 10,000-cubic yard site including equipment, power and
post-waste treatment, the cost is on the order of $37.5 per cubic yard.
45
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B4
Research: Electrokinetic Enhancement9
Developer(s): Environmental & Technology Services (ETS)
Contact(s): Dr. Walter W. Loo
Environmental & Technology Services
2081 15th Street
San Francisco, CA 94114
Telephone: (415) 861-0810
Fax: (415) 861-3269
Research Description
Several bench scale and field demonstrations of electrokinetic treatment were conducted on selenium,
boron, chlorinated solvents, and fuel hydrocarbons. A description of the various research activities
is explained below.
In 1996 at the Panoche Water Drainage District (PWDD) in Firebaugh, California, ETS conducted
an in-situ electrokinetic treatment project. The objectives of the in-situ treatment were to:
• reduce the dissolved selenium in the PWDD drainage runoff water;
• reduce the dissolved boron in the PWDD drainage water to the extent possible that
the water can be recycled for crop irrigation water uses; and
• reduce the dissolved solids in the PWDD drainage runoff water to the extent possible
that the water can be recycled for crop irrigation water uses.
Q
Information provided was obtained from the following reports:
Loo, W.W. and Chilingar, G.V., Advances in the Electrokinetic Treatment of Hazardous Wastes in Soil and
Groundwater, presented at HAZMACON 97, Santa Clara, California, pp. 1-15 (1997)
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
46
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The in-situ electrokinetic treatment systems were installed and conducted at DP-25 site and Area 27
of PWDD as represented in Figures 16 and 17. ETS recommended that PWDD proceed with the
design of a drainage water quality management program by installing a network of electrokinetic
systems along the interceptor drain at DP-25.
Another research activity includes two case closures at a site located in Emeryville, California, with
the biodegradation of chlorinated solvents (TOX). In 1989, ETS successfully demonstrated the field
closure of the biodegradation of trichloroethene (TCE) and trichloroethane (TCA) together with
toluene in soil through heat and nutrient enhancement by the growth of Bacilli and Pseudomonas
fluorescens. In 1992 and 1993, a TOX contaminated aquifer at the site was remediated by
electrokinetic enhanced in-situ passive cometabolic treatment.
Status
ETS is continuing to conduct research, field and remediation activities involving electrokinetic
treatment of hazardous and toxic wastes in soil and groundwater. Several state-of-the-art remedial
technologies are being invented and implemented for use by Dr. Loo and ETS.
47
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'.'ATER TANK
RANOOHE WATER QRAIWAQe DFSTRSCT PROJECT
X
N
Figure 16
Site map of DP-25 Sump Area (Source: Loo, W.W. and Chilingar, G.V., Advances in the
Electrokinetic Treatment of Hazardous Wastes in Soil and Groundwaten presented at
HAZMACON97, Santa Clara, California, pp. 1-15, 1997)
48
-------
Figure 17
Site map of Area 27 (Source: Loo, W.W. and Chilingar, G.V., Advances in the Electrokinetic Treatment of Hazardous Waste and
Groundwater, presented at HAZMACON 97', Santa Clara, California, pp. 1-15, 1997)
49
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B5
Research: Electrokinetic Extraction10
Developer(s): Isotron Corporation
Contact(s): Henry Lomasney
Isotron Corporation
13152 Chef Menteur Hwy
New Orleans, LA 70129
Telephone: (504) 254-4624
Fax: (504)254-5172
Research Description
The effectiveness of electrokinetics to move and capture uranium and organic contaminants in soil
was carried out in this demonstration project. The demonstration was supported by the U.S. DOE's
Office of Technology and Development. Isotron's concrete decontamination technology applies an
electric field to induce migration of ionic contaminants from within the porous concrete into the
Isotron decontamination unit. The system utilizes the company's patented ELECTROSORB™
process and SEEC™ pad technology (see Figure 18). The electrolyte solution contains materials to
promote formation of a soluble ionic complex of each specific contaminant present. The electrolyte
solution is in contact with the concrete surface through the carpet-like SEEC™ pad, which partially
removes contaminants from the electrolyte solution and limits the bulk flow of the electrolyte
solution. All contaminants are collected in the aqueous electrolyte solution which flows into the
separation module where the contaminants are removed. The contaminants are then collected in a
disposable cylinder or sorbent material.
The SEEC™ pad technology was used on a concrete structure at the K-25 building site in Oak Ridge,
Tennessee. The project combines the use of selective extractants (citrate and carbonate salts) to
Information provided was obtained from the Internet at the Isotron Corporation world wide web site at
http:\\www.isotron.com and the following reports:
Isotron Corporation, Electrokinetic Extraction of Uranium From K-25 Soil, Final Technical Brief', November 1995
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
50
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remove the uranium with electrokinetics to transport the contaminants to ion exchange media. The
media surrounding the electrodes capture and concentrate the uranium for later recovery or disposal
(see Figure 19). The electrokinetics demonstration process was carried out at the K-25 site over an
area measuring 8 feet x 9 feet with an approximate volume of 144 cubic feet contaminated soil. The
depth of the uranium contamination at this site was approximately 2 feet. An average uranium
concentration of 600 ppm was estimated. The demonstration area was covered with 6 SEEC™ pads
and the electrodes are buried at a depth of 2 feet with spacing 4.5 feet apart. A 40-ampere current
is applied at a voltage gradient of 90 volts across the electrodes. The partial cost (not including labor
and excavation cost) for the field demonstration was $95 per ton of soil.
Status
Laboratory tests completed in 1994 using site soil showed that the process could move and capture
99 percent of the uranium. A final treatability test report and a site characterization report was issued
in 1995 (see references). Isotron is continuing to use its patented electrokinetic technologies to
remediate contaminated hazardous waste. Technological advances made by Russian scientists in this
area of environmental remediation are being used as much as possible in conjunction with Isotron's
own technology.
51
-------
"Stet" Pad
(Typical)
___--
Vj
A.Al
Detail A
NA[i,i Pad
Figure 18
General arrangement of a demonstration using SEEC™ Pad technology (Source: Isotron
Corporation, Electrokinetic Extraction of Uranium From K-25 Soil Final Technical Brief,
November 1995)
52
-------
'' Electro-osmosis ' Electrophoresfe '
•OOK,OOO°O<>O/OOOOC
\ . /
Figure 19
A general illustration of contaminant transport processes induced by applying direct current
between buried electrodes (Source: Isotron Corporation world wide web site at
http: \\www. i sotron. com)
53
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B6
Research: Electrokinetic Soil Processing11
Developer(s): Lehigh University
Contact(s): Dr. Sibel Pamukcu
Lehigh University
Department of Civil and Environmental Engineering
Fritz Engineering Laboratory
13 East Packer Ave.
Bethlehem, PA 18015
Telephone: (610) 758-3220
Fax: (610) 758-4522
E-mail: sp01@lehigh.edu
Research Description
The critical parameters of electroosmosis and flow enhancing ions have been investigated in a series
of laboratory experiments. Laboratory tests on soil contents collected from a former manufactured
gas plant (MGP) site indicate that electrokinetic processes can assist in the transport and removal of
coal tar constituents from contaminated soils.
From 1992 to 1993, investigators conducted long-term electrokinetic tests on soil cores collected
from a former MGP site. Some of the tests were enhanced by injecting solubilizing agents
(surfactants) into the soil. Researchers subjected samples to varying levels of water flow, depending
on the physical properties of the soil, for a period of 3 to 4 weeks. During each test, they monitored
the systems for voltage, current, and in-flow and out-flow of liquid through the soil. After each test,
they analyzed soil specimens for polynuclear aromatic hydrocarbon (PAH) concentration profiles and
pH profiles to determine the extent of PAH transport and removal.
Information provided was obtained from the following reports:
Pamukcu, S., Electrokinetic Removal of Coal Tar Constituents from Contaminated Soils , Electric Power Research
Institute Report, EPRI-TR-103320, Palo Alto, CA, p 32 (1994)
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
54
-------
The study demonstrated successful removal of 16 targeted PAH compounds from the soil (clay or
granular) at a removal rate of 44 to 70 percent upon 2 to 9 pore-volumes of electro-osmotic water
flow through the soil specimens. In general, the degree of success of decontamination by
electrokinetic processes appeared to be parameter specific; more dependent on the type of the
contaminant to be removed than the type of medium being contaminated. Electroosmosis appeared
to be the dominant mechanism of transport when the contaminants present in the aqueous phase were
nonpolar or nonionic, neutral micelles or surface-coated colloids.
Investigations of clay or clay mixtures and a known concentration of a selected heavy metal salt
solution or an organic compound (such as sodium dodecylbenzene sulfonate) showed up to 99
percent heavy metal removal, and high removals of some organic compounds such as phenol, acetic
acid, and O-nitrophenol. In addition, removal of radionuclides was also achieved. A cost evaluation
based on laboratory results and previous in-field investigations provided the basis for estimating the
treatment costs. For a 10,000 cubic yard site including equipment, power and post-waste treatment,
the cost is on the order of $37.5 per cubic yard.
Status
Further research and development of this method is being conducted to determine if the
electrokinetics process can be used on a field scale to provide a reliable method for in-situ
remediation of MGP sites.
55
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B7
Research: Electrokinetic Remediation12
Developer(s): Lynntech, Inc.
Contact(s): Dr. Tom Rogers or Dr. Dalibor Hodko
Lynntech, Inc.
7610 Eastmark Drive, Suite 105
College Station, TX 77840
Telephone: (409) 693-0017
Fax: (409) 764-7479
Research Description
Researchers at Lynntech have studied methods to combine electrokinetics and bioremediation, an
effective low environmental impact treatment process, for in situ degradation of a wide range of
organic pollutants. Bioremediation has two major disadvantages: 1) slow rate of action; and 2) its
adverse effect on low permeability soil (such as clay). Electrokinetic process can overcome these
disadvantages by:
• enabling movement and delivery of essential nutrients to the anaerobes; and
• uniform delivery of nutrients in low permeability soils
Although this method is in its early stage of development, there is an enormous commercial potential
for this technology because of its low cost of implementation.
Lynntech has also successfully completed a 3-month field demonstration test for removal of heavy
metals from soil at Radford Army Ammunition Plant in Radford, VA. During this test, more than 65
percent of lead contamination was removed. The method does not involve excavation or offsite
transportation, does not create any environmental impact and is a favorable approach in terms of
public perception.
Information provided was obtained from the following report:
Hodko, D. and Rogers, T.D., Lynntech, Inc. Electrokinetics Technology Capabilities Brochure , August, 1997
56
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The treatment costs, based on actual field experience range from $65-$ 125 per cubic yard of treated
soil. The Lynntech field technology (see Figures 20 and 21) is fully automated and once installed,
can be operated and monitored remotely, thus minimizing process and project cost.
Status
Lynntech is at present conducting a field demonstration in Florida at the Kennedy Space Center to
practically apply the combinational bioremediation-electrokinetic process based on laboratory tests.
This project is being conducted for the National Aeronautics and Space Administration (NASA)
under the Small Business Innovative Research (SBIR) program. A summary of Lynntech's completed
and ongoing electrokinetic projects is listed in Table 6.
57
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Figure 20
Lynntech's Electrokinetic Field Technology (Source: Lynntech, Inc. capabilities brochure)
Figure 21
Lynntech's Electrokinetic Field Technology (Source: Lynntech, Inc. capabilities brochure)
58
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Table 6
Successfully completed or on-going electrokinetic remediation projects carried out by Lynntech
since 1993 (Source: Lynntech, Inc. capabilities brochure)
Project Title
Pulsed DC Electric Fields for Heavy
Metals Decontamination of Soil
Pulsed DC Electric Fields for Heavy
Metals Decontamination of Soil
- Field demonstrated in 1995
Dielectrophoresis: Application to
Polluted Soil Remediation
In Situ Degradation of Dioxins by
Chemical Oxidation
In Situ Degradation of Dioxins by
Chemical Oxidation
- Field demonstrated in 1997
Engineered Bioremediation of
Contaminated Soil Through
Enhancement of Microbial
Populations
Engineered Bioremediation of
Contaminated Soil Through
Enhancement of Microbial
Populations
- 9-month field demonstration in
progress at Kennedy Space Center
New Electrochemical Process for In
Situ Soil Decontamination
A Micromodel Study of Residual
Hydrocarbon Mass Transfer Rates in
Porous Media
Client
DOD: $50K
9/92 - 3/93
DOD: $683K
9/92 -12/95
NSF: $65K
1/94 - 8/94
DOD (Air Force):
$58K
5/94-11/94
DOD (Air Force):
$705K
5/95 - 5/97
NASA: $70K
11/94-5/95
NASA: $539K
3/96 - 3/98
NSF: $65K
1/95 - 6/95
DOD (Air Force):
$80K
7/95 - 1/96
Accomplishment
One of the first demonstrations of the value of non-
uniform electric fields in electrokinetics
Successful field implementation of electrokinetic
for metal recovery. Significant developments
made in process design and control
Implemented new electric field effects with unique
applications to nonmetallic contaminants
Laboratory demonstration of a combined
electrokinetic/soil oxidation system
At the time of its initiation, the first field scale
implementation of electrokinetics for chemical
oxidant delivery. Made substantial improvements
in field hardware and installation procedures
A laboratory system demonstrating the use of
electrokinetic soil processing to enhance
bioremediation
Field demonstration of electrokinetics to control
soil redox chemistry to promote anaerobic
biodegradation of chlorinated solvents.
Advancements in electrode well designs made
Novel cathode designs were investigated as a
unique method to control the redox chemistry
surrounding the electrodes
Development of a unique understanding of the
effects of electrokinetics at the microscopic level
59
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Table 6 (continued)
Successfully completed or on-going electrokinetic remediation projects carried out by Lynntech
since 1993 (Source: Lynntech, Inc. capabilities brochure)
Project Title
Client
Accomplishment
Transport of Colloidal Size Particles
Through Porous Media: A New
Approach for Formation of
Impermeable and Reactive
Subsurface Barriers
NSF: $70K
1/97-6/97
The first laboratory demonstration of electrokinetic
technology for in situ barrier emplacement
Soil Treatability Study Remedial
Services: Camp Stanley Storage
Activity Area
- Field demonstration in progress
Parsons
Engineering:
$73.5K
4/96 - 9/96
An ongoing field demonstration of the use of non-
uniform electric fields at a site contaminated with
chromium
Electrokinetic Demonstration:
NAWS Point Magu, CA
- 9-month field demonstration
planned at 2 test sites in 1998
LB&M Assoc.,
Inc.: $756K
8/97-11/98
Remediation of chromium in a tidal marsh area
60
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B7
Research: Electroremediation13
Developer(s): Massachusetts Institute of Technology (MIT)
Contact(s): Dr. Ronald F. Probstein
MIT Department of Mechanical Engineering
77 Massachusetts Avenue
Cambridge, MA 02139
Telephone: (617) 253-2240
Fax: (617) 258-8559
E-mail: rfprobst@mit.edu
Research Description
MIT researchers used laboratory experiments and mathematical modeling to study the changes in the
flows of ions and pore liquid during the removal of contaminants from soils using electric fields. The
flows are directly related to the removal of charged and uncharged contaminants by electromigration
and electroosmosis, respectively. The laboratory experiments consist of purging a prepared kaolinite
sample which is loaded with a known amount of phenol or acetic acid.
The process of electro-osmotic purging uses an electric field that is applied to soils which are
saturated or partially saturated with contaminated water (see Figure 22). The applied electric field
moves the water and dissolved contaminants to the electrode wells where they may be pumped to the
Information provided was obtained from the following journals and reports:
Jacobs, R.A. and Probstein, R.F., Two-Dimensional Modeling of Electroremediation, AIChEJ. 42, pp. 1685-1696 (1996)
Jacobs, R.A., Sengun, M.Z., Hicks, R.E., and Probstein, R.F., Model and Experiments on Soil Remediation by Electric
Fields, J. Em. Sci & Health, 29A , No.9 (1994)
Probstein, R.F. and Hicks, R.E., Removal of Contaminants from Soils by Electric Fields , Science 260, pp. 498-503 (1993)
Probstein, R.F. and Shapiro, A.P., Removal of Contaminants from Saturated Clay by Electroosmosis , Env. Sci. &
Technology 27, pp. 283-291 (1993)
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
61
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surface. A nontoxic purge solution that is drawn in at one of the electrodes is used to wash the soil
and to prevent the formation of cracks by maintaining soil saturation. The solution may contain
reagents to enhance the mobility of contaminants that are not originally present in the aqueous phase.
ADC power connected to the carbon electrodes - 1.5 centimeters deep and placed 20 centimeters
apart — was controlled to maintain a constant voltage of 20 volts across the clay. The process is
shown to be very effective at removing organics such as phenol and acetic acid from clay, achieving
at least 94 percent removal under certain conditions, and has also shown 98 percent removal of heavy
metals such as zinc.
The factors which determine the success of the decontamination are the combined effects of electro-
osmotic convection, ionic migration, chemical equilibria, and electrochemical reactions. These
phenomena are analyzed in a model which compares favorably with experiments. The one-
dimensional mathematical model takes into account the complex interaction of subsurface effects that
occur simultaneously when a direct current is applied in soil. The model can also describe
complexation, dissolution and precipitation reactions, surface complexation and sorption processes,
and electrochemical reactions. Both the experiments and the mathematical model show the
development of sharp fronts, some propagating with the electro-osmotic flow and others stationary
at the electrodes. The pH of the purging solution is shown to have significant influence on the
electro-osmotic velocity and can be selected to optimize the process.
Status
MIT has been conducting research on electroremediation for the past 10 years. This research, which
is sponsored by DOE, is expected to improve the efficiency and reduce the cost of practical
applications of the technology. It is expected that the model developed will provide an important
guide to laboratory and pilot-scale treatability studies.
Recently, researchers at MIT have developed a two-dimensional model and numerical code for the
simulation of contaminant removal from soils by electric fields. Like the one-dimensional model, this
model also describes the coupled transport of mass and charge, and the chemical speciation of a
multicomponent system subjected to an electric field. The two-dimensional model was developed to
address the variation of the current density with the geometry of the electrode array. The computer
code developed for the two-dimensional model, computes the time evolution of several state variables
(including the spatial distributions of the electrostatic potential and pressure, the current density, and
all species velocities and concentrations) in a multielectrode, multicomponent system of arbitrary
shape subject to an electric field (see Figure 23). The results from this model can be applied to three-
dimensional systems in which the distance between electrodes is small compared to their length, and
there is no significant variation of the material properties with depth.
62
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Laboratory experiments applying DC electric fields to soils containing aqueous solutions of soluble
contaminants show potential for an effective in situ means for cleaning waste sites. Limited field tests
and computer modeling support this projection, although the ability to make quantitative predictions
of expected contaminant removal and costs at an actual hazardous waste site is at an early stage.
Several development steps are needed to assess this method's potential: the results of well
characterized field tests together with additional laboratory data, particularly on the removal of heavy
metals and their interactions with different soils of varying degrees of saturation; reagents for
enhancing the desorption and solubilization of both organic and inorganic contaminants; and
improved predictive models that enable optimization of the process variables. MIT researchers are
at present carrying out a field test in New Jersey on a chromate contaminated site under EPA
auspices, but the test is essentially just starting and no results are available as yet.
Laboratory experiments on organics removal by electroosmosis purging at moderate voltages, so that
heating losses are not excessive, show energy costs averaging about 20kWh per cubic meter of
effluent. The estimated energy costs for contaminant removal by electric fields based on the
experiments, could approximate $20 to $30 per ton.
63
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Figure 22
Schematic of a field installation for in situ remediation by electro-osmotic purging (Source:
Probstein, R.F. and Shapiro, A.P., Removal of Contaminants from Saturated Clay by
Electroosmosis. Env. Sci. & Technology 27, pp. 283-291, 1993)
Figure 23
2-D multielectrode system (Source: Jacobs, R.A. and Probstein, R.F., Two-Dimensional
Modeling of Electroremediation. AIChE J. 42, pp. 1685-1696, 1996)
64
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B8
Research: In Situ Electrokinetic Extraction System14
Developer(s): Sandia National Laboratories (SNL)
Contact(s): Eric R. Lindgren
Sandia National Laboratory
P.O. Box 5800, Mail Stop 0727
Albuquerque, NM 87185
Telephone: (505) 844-3820
Fax: (505) 844-1480
E-mail: ERLINDG@sandia.gov
Research Description
The purpose of this research is to develop an in situ electrokinetic process for remediating
unsaturated soils (as low as about 25 percent saturation) contaminated with anionic (negatively
charged) heavy metals (such as chromium and radionuclides) without raising soil moisture content
significantly. In sandy soils with approximately 40 to 60 percent moisture saturation, the bench scale
electrokinetic process removed 75 to 90 percent chromium. Chromium contamination is of interest
because it is one of the most significant contaminants in the SNL Chemical Waste Landfill (CWL)
Unlined Chromic Acid Pit (UCAP) (see Figures 24 and 25). At the CWL, electrokinetics has been
used to remove negatively charged chromium ions from the chromate plume in the vadose zone below
the UCAP. Chromium contamination has been detected to a depth of 75 feet at the CWL.
Three to five electrode pairs, supplied with water and neutralization chemicals, were used to treat
chromium-contaminated soil over a 120-day period. Between 25 and 120 kilograms of chromium
was removed from 700 to 1,000 cubic feet of soil. Soluble chromium concentrations range from 25
(background) to 10,000 ppm with the upper limit at 15 feet below ground surface. Contaminants
arriving at the electrode were removed using a vacuum system. To use the electrokinetic system,
electrodes are installed in the ground in a square array and connected to a DC voltage power supply
Information provided was obtained from the Internet at the Sandia National Laboratory world wide web site at
http:\\www.sandia.gov and the following report:
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
65
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(see Figures 26 and 27). Each electrode assembly contains water, a pump, an electrode, and
numerous sensors and controllers. The outer casings of the electrodes are made of porous ceramic
which allows electrical current and contaminants to pass. A vacuum is applied to the casings which
keeps the water inside the assembly from flowing out and saturating neighboring soils. The
electrodes are placed in the predetermined treatment zone with the ceramic casing at the treatment
depth of 15 feet below ground surface. When the DC power supply is applied to the soil between
electrodes, water flows in the soil pores (usually towards the cathode). The SNL electrode design,
however, allows water to enter the soil at the anode, supplying the pore water adjacent to the
electrode casing but never saturating the soil. The ions are then pumped to the surface by circulating
water within the ceramic casing. Electrode effluent containing chromate contamination is shown in
Figure 28.
A major advantage of this particular electrokinetic system is that it operates in unsaturated soil for
much longer periods of time than if simple electrodes were used. In addition, the process needs
relatively limited amounts of energy compared to excavation: a 40K watt portable diesel generator
can power the system. A major limitation to this process is that buried metal objects divert the
current from the soil needing remediation. Another problem can arise if large amounts of nontargeted
contaminants are present in the soil to be treated. Estimates for electrokinetic remediation range from
$50 to $150 per ton. Processes involving excavation of soil cost $200 to $500 per ton.
Status
Research and demonstrations at SNL are supported by DOE. The technology was developed and
tested at the bench and pilot scale in 1993. In 1994, a prototype electrode system was field-tested
in the UCAP, inside the CWL, to characterize the process and to demonstrate in situ water control
in unsaturated soil. Efforts are underway to extend the technology to treat cationic contaminants
which adsorb strongly to soil or exist as solid precipitates. Organic complexants are electrokinetically
injected into the soil at the cathode and form anionic complexes with certain contaminants which are
attracted to and removed from the anodes. The SNL In Situ Electrokinetic Extraction System was
also demonstrated at SNLs UCAP from May 15 to November 24,1996, and evaluated under the EPA
SITE Program. The target contaminant for the demonstration was hexavalent chromium in the form
of chromate ions. SNL researchers indicate that this process can also be used for uranium removal
at DOE's Hanford site. Commercial availability of the technology is expected in 1998.
66
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Figure 24
Electrokinetic demonstration for chromate removal at the Unlined Chromate Acid Pit (Sandia
National Laboratories, Tech Area III, Chemical Waste Landfill) (Source: Sandia National
Laboratory world wide web site at http:\\www.sandia.gov)
67
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Figure 25
Aerial photo of electrokinetic site over the Unlined Chromic Acid Pit (Sandia National
Laboratories, Tech Area III, Chemical Waste Landfill) (Source: Sandia National Laboratory
world wide web site at http:\\www.sandia.gov)
68
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Figure 26
Electrode array configuration for electrokinetic remediation of the Unlined Chromic Acid Pit
(Source: Sandia National Laboratory world wide web site at httpAWww.sandia.gov)
69
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Electrophoresis
inouemoit of palOclcs
Figure 27
Electrokinetic remediation schematic (Source: Sandia National Laboratory world wide web site
at http: \\www. sandia.gov)
70
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Figure 28
Electrode effluent containing chromate contamination (Sandia National Laboratories, Tech Area
III, Chemical Waste Landfill) (Source: Sandia National Laboratory world wide web site at
http: \\www. sandia.gov)
71
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B9
Research: Electrokinetic Extraction15
Developer(s): Texas A&M University
Contact(s): Dr. Albert T. Yueng
Texas A&M Department of Civil Engineering
College Station, TX 77843-3136
Telephone: (409) 845-6554
Fax: (409) 845-6554
E-mail: alyeung@tamu.edu
Research Description
Basic electrokinetic phenomena in clay and the fundamental contaminant removal mechanisms by
electrokinetics was studied by researchers. The research was conducted for the U.S. Army Corps
of Engineers (USAGE) Waterways Experiment Station under the Installation Restoration Research
Program. The research was funded in part with federal funds as part of the program of the Gulf
Coast Hazardous Substance Research Center which is supported by the EPA, and in part with funds
from the State of Texas as part of the program of the Texas Hazardous Waste Research Center.
A coupled flow theory for the transport of fluid, electricity, and chemical gradients to describe the
contaminant transport during the electrokinetic extraction process was formulated. Electrochemical
reactions associated with the processes and soil-contaminant interactions are also included. A
numerical model was developed to simulate the contaminant transport, electrochemical reactions, and
Information provided was obtained from the following journals and reports:
Alshawabkeh, A.N. and Yueng, A.T., Practical Aspects of In-situ Electrokinetic Extraction, submitted to the Practice
Periodical of Hazardous, Toxic, and Radioactive Waste Management of ASCE for review and possible
publication on April 29, 1997
Datla, S. and Yeung, A.T., Subsurface Migration of Contaminants under the Coupled Influences of Hydraulic, Electrical,
and Chemical Gradients, Proceedings of the 8 * International Conference of the International Association of
Computer Methods and Advances in Geomechanics , Morgantown, West Virginia, pp. 1042-1048 (1994)
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
72
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soil-contaminant interactions during the extraction processes. Bench scale experiments on the
cleanup of contaminants - such as sodium chloride, lead nitrate, phenol, and acetic acid - from
Milwhite kaolinite (a commercial product from Patria Packaging, Inc., Valdosta, Georgia) were
performed to evaluate the validity of the theory and numerical model. The results obtained from the
extraction of lead from Milwhite kaolinite (using disodium ethylnediaminetetraacetate (EDTA) as an
enhancement agent) show that the removal of contaminants started towards the end of the samples
and slowly migrated inwards. Low pH conditions developed at the anode and high pH conditions
developed at the cathode. The research shows that the validity of the theoretical model is supported
by experimentally measured results, but there is need to develop guidelines and to optimize operation
parameters for the electrokinetics process.
Status
In the laboratory experiments, an example of a contaminated area of 50 meters x 100 meters was
considered. The depth of contamination was assumed to be 5 meters and the soil is saturated silty
clay. Remediation time is assumed to be 6 months. The electrodes were placed 5.2 meters apart and
the electric voltage across opposite electrodes was 100 volts. The total costs per unit volume based
on these parameters was determined to be $38.5. The viability of the research undertaken on
electrokinetics extraction, an emerging in-situ technology, is being continued to be established by
many bench-scale and large-scale experiments, and pilot-scale field investigations, but is not in use
as a remediation tool. Some important practical aspects such as a cost analysis and design criteria
need to be considered before the technology can be successfully implemented in the field.
73
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CATEGORY C
Electrokinetic processes which are currently in the conceptual development
stage
74
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Table 7
Category C Summary Table
Name of
developer(s)
University of
Massachusetts at
Lowell
West Virginia
University
Soil
type(s)
tested
kaolinite
and fine-
grained
soils
fine-
grained
soil
Distance
between
electrodes
not
available
not
available
Depth the
electrodes
were
placed in
not
available
not
available
Voltage
and/or
DC
current
level
not
available
not
available
Processing
fluid(s)
natural and
synthetic
flushing
solutions
not available
Size of
remediation
area
not available
not available
Contaminant(s)
treated
lead, benzene,
toluene, m-
xylene, TCE
lead
Time to
complete
cleanup
not
available
not
available
Contaminant
concentration
levels
not available
not available
Treatment
cost
not available
not available
Cl
75
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Research: Electrokinetics16
Developer(s): University of Massachusetts at Lowell
Contact(s): Dr. Clifford Bruell
University of Massachusetts at Lowell
Civil Environmental Department
One University Avenue
Lowell, MA 01854
Telephone: (508) 934-2280
Fax: (508) 934-3052
Research Description
Since 1992, researchers have been conducting laboratory studies on the effectiveness of
electroosmosis for removing hydrocarbons and heavy metals from clay. Benzene, toluene, TCE
and m-xylene — all of which have relatively high water solubilities — were more easily removed
from fine-grained soils than hexane and isooctane and other compounds with low water
solubilities and high distribution coefficients. Researchers also are studying the physical and
chemical characteristics of electro-osmotic contaminant transport. The data are being used to
gain insights into electro-osmotic organic contaminant displacement and how soil and pore water
characteristics affect the process.
Status
In 1996, additional laboratory experiments for the use of electrokinetics in combination with
natural and synthetic flushing solutions were studied to determine their efficiency in removing lead
from clay. Natural flushing solutions were prepared by mixing water and clay in varying ratios by
weight. An ideal ratio was determined through a comparison of lead removal efficiencies. The
Information provided was obtained from the following reports:
Bruell, C.J., Coletta, T.F., Inyang, H.I., and Ryan, D.K., Electrokinetics and Ionic Solutions to Remove Lead from Kaolin
Clay, presented at the 3rd International Symposium on Environmental Geotechnology, June 10-12, 1996
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
76
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primary elemental constituents of the natural solution were then determined. A synthetic solution
with varying concentrations of aluminum and calcium was made and compared to the natural
solution for lead removal efficiency. The synthetic solutions of aluminum and calcium with the
highest efficiency were then compared. In the final analysis, it was determined that the
concentrations of the elemental constituents of the flushing solution complemented the
electrokinetic removal of lead and Kaolinite clay.
77
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C2
Research: In Situ Electrokinetics17
Developer(s): West Virginia University
Contact(s): Dr. Brian Reed
West Virginia University
Department of Civil and Environmental Engineering
647 Engineering Science Building
Morgantown, WV 26506
Telephone: (304) 293-3031 Ext. 613
E-mail: reed@cemr.wvu.edu
Research Description
Research on the use of electrokinetics to remediate fine-grained soil contaminated with lead was
conducted. The research included an evaluation of the impact of initial conditions on the
efficiency of electrokinetics to drive liquids and contaminants through soil samples. An
electrokinetic soil reactor designed to mimic in situ electrokinetic flushing was applied to silt loam
artificially contaminated with lead. Studies of the removal of lead from soils indicate that the
efficiency of lead removal is related to the flow of the acid front generated by the positive
electrode.
Status
The DOE National Research Center for Coal and Energy sponsored the laboratory studies
between September 30, 1987, and June 30, 1993. Recent research on electrokinetics processing
has not been undertaken by the university for the past few years.
Information provided was obtained from the following report:
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency Response, In Situ Remediation
Technology: Electrokinetics, EPA542-K-94-007, April 1995
78
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