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 SOLVENT EXTRACTION

This profile provides the following general information about this
treatment process:

1.   Description
2.   Applicability
3.   Limitations
4.   Availability and vendor list
5.   Performance data and field applications
6.   Sources of information for this profile



1.   Description:

Solvent extraction does not destroy wastes but is a means of
separating hazardous contaminants from soils, sludges, and
sediments, thereby reducing the volume of the hazardous waste that
must be treated.  The technology uses an organic chemical as a
solvent and differs from soil washing, which generally uses water
or water with wash-improving additives.  Commercial-scale units
are in operation; they vary in regard to the solvent employed,
type of equipment used, and mode of operation.

Solvent extraction is commonly used in combination with other
technologies, such as solidification/stabilization, incineration,
or soil washing, depending upon site-specific conditions.  It also
can be used as a standalone technology in some instances. 
Organically bound metals can be extracted along with the target
organic contaminants, thereby creating residuals with special
handling requirements.  Traces of solvent may remain within the
treated soil matrix, so the toxicity of the solvent is an
important consideration.  The treated media are usually returned
to the site after having met Best Demonstrated Available
Technology (BDAT) and other standards



2.   APPLICABILITY

Solvent extraction has been shown to be effective in treating
sediments, sludges, and soils containing primarily organic
contaminants such as PCBs, VOCs, halogenated solvents, and
petroleum wastes.  The technology is generally not used for
extracting inorganics (i.e., acids, bases, salts, or heavy
metals).  Inorganics usually do not have a detrimental effect on
the extraction of the organic components, and sometimes metals
that pass through the process experience a beneficial effect by
changing the chemical compound to a less toxic or leachable form. 
The process has been shown to be applicable for the separation of
the organic contaminants in paint wastes, synthetic rubber process
wastes, coal tar wastes, drilling muds, wood-treating wastes,
separation sludges, pesticide/insecticide wastes, and petroleum
refinery oily wastes.



3.   LIMITATIONS

Factors that may limit the applicability and effectiveness of the
process include:

     Organically bound metals can be extracted along with the
     target organic pollutants, which restricts handling of the
     residuals.

     The presence of detergents and emulsifiers can unfavorably
     influence the extraction performance.

     Traces of solvent may remain in the treated solids; the
     toxicity of the solvent is an important consideration.

     Solvent extraction is generally least effective on very high
     molecular weight organic and very hydrophilic substances.

     Some soil types and moisture content levels will adversely
     impact process performance



4.   AVAILABILITY AND VENDOR LIST

Solvent extraction is commercially avaiilable from several
vendors, listed below.

Art International, Inc.                      (201) 627-7601
CF Systems Corporation                       (617) 937-0800
Dehydro-Tech Corporation                     (201) 887-2182
EM&C Engineering Associates                  (714) 957-6429
Envirogen, Inc.                              (609) 936-9300
Geo-Microbial Technologies, Inc.             (918) 535-2281
Integrated Chemistries, Inc.                 (612) 636-2380
Nukem Development                            (713) 520-9494
Resources Conservation Co.                   (301) 596-6066
SRE, Inc.                                    (201) 661-5192
Terra-Kleen Corporation                      (405) 728-0001



5.   PERFORMANCE DATA AND FIELD APPLICATIONS



The ability of RCC's full-scale B.E.S.T.  process to separate oily
feedstock into product fractions was evaluated by EPA at the
General Refining Superfund site near Savannah, Georgia, in
February 1987.  The treated soils from this unit were backfilled
to the site, product oil was recycled as a fuel oil blend, and the
recovered water was pH-adjusted and transported to a local
industrial wastewater treatment facility.

CF Systems completed a SITE program demonstration on PCB-bearing
sediment at New Bedford Harbor, MA.  Extraction efficiencies were
high (99.9 percent) despite some operating difficulties.

DehydroTech (Carver-Greenfield Process) completed a SITE program
demonstration at the EPA testing facility in NJ and Terra Kleen
(Solvent Extraction) completed a SITE demonstration at the Naval
Air Station North Island in San Diego.



6.   Source: 

Marks, Peter J., Walter J. Wujcik and Amy F. Loncar, October 1994.
REMEDIATION TECHNOLOGIES SCREENING MATRIX AND REFERENCE GUIDE,
SECOND EDITION.  DOD Environmental Technology Transfer Committee.
NTIS No. PB95-104782.  Reproduced for the Bloomington, Indiana PCB
Superfund Sites Bulletin Board with the permission of USAEC, 
SFIM-AEC-ETD, APG, MD. Supplemented by MVA Consulting, Inc.
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