&EPA
United States
Environmental Protection
Agency
Solid Waste and
Emergency Response
(5102W)
EPA542-S-95-001
April 1995
Emerging Abiotic In SJitu
Remediation Technologies for
Ground Water and Soil
Summary Report
Purpose
This document summarizes the status and trends in the develop-
ment of abiotic technologies to treat contaminated ground water
in-place or increase contaminant solubility and mobility to
improve their removal by pumping. It is an overview of six status
reports that document demonstrations and research on specific
emerging abiotic technologies. This information will allow
stakeholders to understand the current investments in emerging
abiotic technologies and make more informed decisions concern-
ing their use for remediation.
This document and the underlying status reports do not cover
trends in the use of bioremediation. EPA has other resources
summarizing the progress of bioremediation technologies. See the
section of "Related Information Sources" for information about
the Bioremediation in the Field newsletter and the Bioremediation
in the Field Search System database. The database contains
information on the status of over 400 sites where bioremediation
is being applied, and the newsletter provides updates on perfor-
mance evaluations of new technologies, resources, and regula-
tions affecting the use of bioremediation. At these sites, a broad
range of in situ and ex situ biotreatments are being applied,
-including land treatment, bioventing, bioreactor treatment,
nutrient addition, and many other techniques.
Method
EPA has identified six abiotic technologies that are emerging as
possible clean-up remedies. For each technology, EPA has
produced a separate report identifying research projects, demon-
strations, and field applications of the technology. The technolo-
gies are:
surfactant enhancements
treatment walls
hydraulic fracturing/pneumatic fracturing
cosolvents
electrokinetics
thermal enhancements
Information in each report was found in computerized databases
such as EPA's Vendor Information System for Innovative Treat-
ment Technologies (VISITT) and Alternative Treatment Technolo-
gies Information Center (ATTIC) and databases available from
Knight-Ridder Information Services; and in publications such as
the Hazardous Substance Research Center Annual Reports, the
Superfund Innovative Technology Evaluation Technology
Profiles and the Department of Energy Office of Technology
Development Program Summary. The review also included
conference summaries, proceedings, and compendia. It was
supplemented with personal interviews and discussions with
representatives of other federal agencies, academic research
centers, and hazardous waste remediation consulting firms.
Technology Needs
The predominance of ground-water contamination at hazardous
waste sites and the lack of methods to treat the contamination is a
problem of great concern to EPA. According to a recent report
released by the National Research Council, there are approxi-
mately 300,000-400,000 contaminated waste sites'. The contami-
nated ground water found at Superfund sites is often the limiting
factor for complete site remediation. Until recently, many
believed that contaminants In surface soils were the only signifi-
cant source of ground-water contamination. Consequently,
development of remediation technologies focused mainly on this
source. Ground-water treatment was limited to pump-and-treat
technology while in situ ground-water treatment was ignored.
Technologies to remediate contaminated ground water in situ are
not yet well developed, primarily because contaminated ground
water plumes are difficult to define, contaminants can migrate in
different directions simultaneously, and, in most cases, the
subsurface is unreachable for in situ characterization.
Researchers and regulators studying data from pump-and-treat
remediation systems have become convinced that the source of
much ground-water contamination is dense non-aqueous phase
liquids (DNAPLs) and other compounds that migrate downward
into aquifers and often form pools of subsurface contaminants. In
these cases, the efficiency of contaminant removal is contingent
on solubility of the contaminant, efficacy of the pumping system,
and hydraulic characteristics of the aquifer. Unless they directly
remove the contaminant source, pump-and-treat systems only
treat the symptom (solubilized contaminants), and not the cause.
Because of this, there is a need for technologies that improve the
efficiency of pumping systems as well as in situ treatment of
contaminated ground water and subsurface contaminant sources.
1
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Technology Descriptions and Analyses
Thermal Enhancements. Thermal enhancement technologies
include the injection of hot water or steam or the use of radio
frequency or electrical resistance heating to increase the mobility,
solubility, or volatility of organic contaminants, particularly
immiscible compounds.
There are approximately 16 completed, ongoing or future
demonstrations. Two demonstrations will be using the "Con-
tained Recovery of Oily Wastes (CROW)," a patented technol-
ogy by Western Research Institute. Almost all the other demon-
strations were or will be conducted at federal facilities. There are
11 completed demonstrations which provide some cost and
performance information. Most of the demonstrations treated
VOCs, SVOCs, and BTEX; however, two demonstrations were
designed to treat PAHs from wood treating sites and one treated
pesticides.
There were only two research projects being conducted. The
dearth of research may be explained by the fact that the physical
site conditions, not chemical reactions, are the major controlling
factors on the use of the technology. Therefore, laboratory
studies, although important, are not critical.
Surfactant Enhancement Surfactants increase the solubility of
the contaminant in water and also increase mobility by reducing
interfacial tension between the contaminant and the soil matrix,
resulting in direct mobilization.
There were 10 demonstrations or commercial applications. Many
of these were supported by the State University of New York
(SUNY) at Buffalo, which conducted much of the early research
for the technology. The target contaminants at the demonstrations
were VOCs, SVOCs, BTEX and one demonstration for PCBs.
There were nine research projects identified, a relatively large
number which reflects the need of laboratory and bench-scale
support. There are a variety of surfactants available and the
effectiveness of each of these to treat a specific contaminant in a
specific geochemical environment is usually unknown until
laboratory and bench scale treatability tests are conducted.
Consequently, research support for this technology is necessary
and important. Research is being supported by a variety of
stakeholders, including the federal government, private industry
and research facilities. All the current research is being conducted
on organic contamination.
Treatment Walls. These are vertical treatment zones installed
across the flow path of a contaminant plume to treat the contami-
nants as the plume passes through the zone. These mechanically
simple barriers may contain metal-based catalysts for degrading
volatile organics, chelators for immobilizing metals, or nutrients
and oxygen to enhance bioremediation.
Four of the 11 ongoing or completed demonstrations are using or
have used in situ metal-enhanced dehalogenation. The patent for
this technology is held by the University of Waterloo. The
remaining demonstrations are testing the use of O2, nutrients for
bioremediation, and chemical reactants to reduce Cr+6. Prelimi-
nary results from four demonstrations are expected in 1995.
There are 10 research projects identified, sponsored primarily by
DOE and EPA. This research is divided between the treatment of
metals and organics.
Hydraulic Fracturing/Pneumatic Fracturing. Fracturing
consists of the injection of pressurized water or air to increase the
size and number of fractures in a consolidated material or
relatively impermeable unconsolidated material. The enlarged
fractures provide more treatment area for an in situ technology or
more pathways to remove solubilized or mobilized contaminants.
Demonstrations of pneumatic fracturing are being conducted by
two vendors, with the New Jersey Institute of Technology
providing a supporting role with research. The demonstrations
were included in the EPA Superfund Innovative Technology
Evaluation (SITE) program. One demonstration of hydraulic
fracturing was included in SITE. There were no current direct
research efforts identified.
Cosolvents. Cosolvents are a form of in situ flushing that
involves the injection of a solvent mixture (e.g., water plus_a
miscible organic solvent such as alcohol) that enhances the
solubility of organic contaminants.
Figure 1: Development Status of VISITT and SITE Program Technologies
Ground Water
Soil
35
30
25
20
15
10
5
0
1992
1993
1992
1993
Developers of 31 technologies claim to treat ground water and soils. Soils in this context also include solids, debris, and sludge. There were a
total of 177 technologies in 1992 and 289 technologies in 1993.
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The use of cosolvents is in the very early stage of development.
No vendors were identified who are marketing the technology
and three planned demonstrations will be conducted by a partner-
ship between a federal laboratory, a military base, and a univer-
sity. One research project was completed in 1991.
Electrokinetics. The basis of this technology is that positively-
charged organic or inorganic contaminants can be made to
migrate in an electric field to a collection point for removal by
pumping. Most of the six demonstrations are being sponsored or
cbsponsored by the federal government (Department of Energy or
Army Corps of Engineers). Of these demonstrations,
approximately half were designed to treat metals and half were
for treating BTEX and TCE. There is a relatively large number of
universities conducting research in electrokinetics, many being
supported by DOE. Louisiana State University (LSU) is heavily
involved in this research and has published over 30 papers. They
are also in partnership with a private company that is deploying
and commercializing the technology. Besides LSU, there are
seven other research facilities conducting studies on the
technology.
The following table (Figure 2) summarizes the number of
activities being conducted to test and demonstrate the six
technologies analyzed in the status reports. The number of
research projects represents the number of research centers
actively conducting research to develop and fine-tune technolo-
gies. The research projects involve technologies that are not
necessarily ready to be demonstrated. Each project consists of
one group, generally a university or laboratory, but in some cases
a technology vendor. The number of ongoing or future demon-
strations represents the number of locations where the technology
is being demonstrated or will be demonstrated in the near future.
The number of completed demonstrations represents the number
of demonstrations that have already taken place. Commercial
applications represent individual sites where the technology is
being used commercially to remediate a site. A single organiza-
Figure 3: Contaminants Treated or Studied During
Demonstrations or Research Projects of
In Situ Technologies
VOCs* Metals BTEX SVOCs* PCBs Pesticides
* Suspected DNAPLs
tion may be involved in more than one demonstration or commer-
cial application.
The amount of activity taking place and the capabilities of the
technologies being studied are good news for the outlook for
cleaning up contaminated, ground water at hazardous waste sites.
Further, the contaminants that are being treated in the technology
demonstrations and applications are among the most commonly
occurring chemicals at hazardous waste sites.
Footnotes |
'National Research Council. Alternatives for Ground Water
Cleanup. Washington, DC: National Academy Press, 1994.
2U.S. Environmental Protection Agency. Profile of Innovative
Technologies and Vendors for Waste Site Remediation. EPA 542-
R-94-002, December 1993.
Figure 2: Development Status of Selected In Situ Technologies
Technology
Thermal
Enhancements
Surfactants
Treatment
Walls
Fracturing
Cosolvents
Electrokinetics
Total
Research
Projects
2
9
11
1
10
33
Ongoing
or Future
Demos
B
6
S
2
3
5
30
Completed
Demos
11
3
2
10
1
27
Commercial
Applications
1
I
2
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Ordering Information for the Status Reports
The full status reports can be ordered from EPA's Center for Environmental Information and Publications (NCEPI). To order, send or fax your name,
address, phone and fax numbers, and the order number(s) of the publication(s) to:
NCEPI
II305 Reed Hartman Highway, Suite219
Cincinnati, OH 45241
513-489-8695 (fax), 513-489-8190 (voice number for confirmation of fax)
The report numbers for the individual reports are as follows:
Surfactant Enhancements: EPA542-K-94-003 Cosolvents: EPA542-K-94-006
Treatment Walls: EPA542-K-94-004 Electrokinetics: EPA542-K-94-007
Hydraulic Fracturing/Pneumatic Fracturing: EPA542-K-94-005 Thermal Enhancements: EPA542-K-94-009
Related Information Sources
The following publications and databases (with the exception of those with an * after the title) are available from NCEPI:
Alternatives for Ground Water Cleanup.* National Research Council Committee on Ground Water Cleanup AlternativesL Washington, DC: National
Academy Press, 1994. ~" - - - - - - -
Bloremediation in the Field (BIF) newsletter and Bioremediation in the Field Search System (BFSS) Database Version 1.0, U.S. Environmental
Protection Agency, Office of Solid Waste and Emergency Response and Office of Research and Development.
Cleaning Up the Nation & Waste Sites: Markets and Technology Trends* U.S. Environmental Protection Agency, Office of Solid Waste and Emer-
gency Response. EPA 542-R-92-012, NTIS order number PB93-140762, April 1993.
Innovative Treatment Technologies: Annual Status Report (Sixth Edition). U.S. Environmental Protection Agency, Office of Solid Waste and
Emergency Response. EPA 542-R-94-005, September 1994.
Profile of Innovative Technologies and Vendors for Waste Site Remediation. U.S. Environmental Protection Agency, Office of Solid Waste and
Emergency Response. EPA 542-R-94-002, December 1993.
Selected Alternative and Innovative Treatment Technologies for Corrective Action and Site Remediation (A Bibliography of EPA Information
Resources): Fall Update. U.S. Environmental Protection Agency. EPA/542/B-93/010, November 1993.
Swpcrfund Innovative Technology Evaluation Program Technology Profiles (Seventh Edition). U.S. Environmental Protection Agency, Office of
Research and Development. EPA/540/R-94/526, November 1994.
Vendor Information System for Innovative Treatment Technologies. U.S. Environmental Protection Agency, Technology Innovation Office. VISITT
Dalabase Version 3.0, Fall 1994.
This material has been funded by the United States Environmental Protection Agency under contract number 68-W2-0004.
Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
xvEPA
United States
Environmental Protection
Agency
(5102W)
Washington, DC 20460
Official Business
Penally for Private Use
$300
EPA542-S-95-001
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