United States
Environmental Protection
Agency
EPA/540/MR-94/521
September 1994
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration Bulletin
Terra-Kleen Solvent Extraction Technology
Terra-Kleen Response Group, Inc.
Technology Description: The Terra-Kleen Solvent Extrac-
tion Technology was developed by Terra-Kleen Response
Group, Inc., to remove polychtorinated biphenyls (PCB) and
other organic constituents from contaminated soil. This batch
process system uses a proprietary solvent at ambient tem-
peratures to treat the contaminated soil. The system in-
cludes a solvent regeneration system that concentrates the
extracted contaminants and allows the extracted solvent to
be reused. Following treatment, clean soils are returned to
the site, and the concentrated contaminant is sent off site for
disposal.
A schematic diagram of the pilot-scale treatment system
that was used in the Superfund Innovative Technology Evalu-
ation (SITE) demonstration is shown in Figure 1. The sys-
tem includes the following equipment: five extraction tanks
(tanks A through E), a sedimentation tank, a microfiltration unit, a
solvent purification station, a clean solvent storage tank, and a
vacuum extraction system. Since the solvent used is flammable,
pneumatic, and spark-proof pumping systems are used to move
the solvent and vapor through the system, thus maintaining an
intrinsically safe environment.
Treatment begins after the excavated soil is loaded into the
extraction tanks. Screening of solids is not necessary, but may
be advantageous when large rocks and/or debris are present.
Clean solvent from the solvent storage tank is then pumped into
the extraction tanks. The soil and solvent are held in the extrac-
tion tank for a time period sufficient to solubilize organic contami-
nants, separating them from the soil. The contaminant-laden
solvent is then transferred from the extraction tank into the
sedimentation tank. Clarified solvent is pumped to the micro-
1 Ton
untreated soil
1 Ton
untreated sol
1 Ton
untreated soil
1 Ton
untreated sol
1 Ton
untreated soil
Vacuum extraction system
j
Contaminant-laden
solvent
Vent
to
atmosphere
Liquid CMNar Vapor
I Otration oond»na»r pump t
Legend
Untreated sol
-> Air and solvent vapor
Sedimentation tank
Microfiltration
unit
Solvent
purification
station
dean solvent
storage tank
Figure 1. The Terra-Kleen solvent extraction technology as demonstrated.
-------
filtration unit and the solvent purification station prior to recycling.
Solvent wash cycles are continued until a site-specific soil cleanup
level is attained.
Some residual solvent remains in the soil after the wash cycles
are completed. Vacuum extraction is used to remove the majority
of the residual solvent by drawing solvent vapor through a con-
denser and liquid filter. Following vapor extraction, an active
biological culture is added to the treated soil to biodegrade any
remaining residual solvent. Finally, the treated soils are removed
from the extraction tanks.
The solvent regeneration process begins by pumping contami-
nant-laden solvent from the sedimentation tank through a
microfiltration unit and a proprietary solvent purification station.
The microfiltration unit removes any fines remaining in the sol-
vent. The solvent purification station separates organic contami-
nants from the solvent and concentrates them, reducing the
volume of hazardous waste for offsrte disposal. The regenerated
solvent is then pumped into the clean solvent storage tank for use
in subsequent wash cycles.
Waste Applicability: The Terra-Kleen solvent extraction technol-
ogy is a volume reduction process designed to remove semivolatile
and volatile organic contaminants from soils, specifically: RGBs,
petroleum hydrocarbons, chlorinated hydrocarbons, polycyclic aro-
matic hydrocarbons, polychlorinated dibenzo-p-dioxins (PCDD),
pesticides, and polychlorinated dibenzo-p-furans (PCDF).
The system is transportable and can be configured to treat small
volumes of soil (1-1,000 yd3). Multiple large extraction tanks (20
yd3) can be used to treat higher volumes of contaminated soils.
The technology's effectiveness for removing pesticides from soil
is currently under investigation.
Preliminary Results: Terra-Kleen demonstrated its solvent ex-
traction technology during a SITE demonstration between May 16
and June 11, 1994. The technology demonstrated was at Naval
Air Station North Island's (NASNI) Site 4, which is located near
San Diego, California. As part of the Naval Environmental Lead-
ership Program (NELP), NASNI contracted with Terra-Kleen to
treat approximately five tons of PCB contaminated soil.
Terra-Kleen conducted 11 washing cycles in seven days. Analyti-
cal results showed that the only PCB mixture present in the soil
was Aroclor 1260. Table 1 shows the analytical results of soil
Table 1. Preliminary PCB Removal Results for the Terra-Kleen SITE
Demonstration at Naval Air Station North Island
PCB as Arodor 1260 in milligrams per kilogram (mg/kg)
Extraction Tank Tank A Tank B Tank C Tank D Tank £
Untreated Soil 130
Treated Soil 1.34
140 134 147 170
1.57 1.66 2.64 1.41
Percent
Removal
99.0
98.9
98.8
98.2
99.2
samples collected from each extraction tank. These analysis
were conducted on-site and are preliminary. Additional data qual-
ity checks are being completed on laboratory generated values.
To provide additional information on the technology's capabilities,
samples were also collected and analyzed for volatile and
semivolatile organic compounds, PCDD, and PCDF. These ana-
lytical results and the Terra-Kleen SITE demonstration findings
will be discussed in the SITE technology capsule and the innova-
tive technology evaluation report. Preliminary findings from this
SITE demonstration are summarized as follows:
• PCB Aroclor 1260 concentrations were reduced from an aver-
age of 144 milligrams per kilogram (mg/kg) in untreated soil to
an average of 1.72 mg/kg in treated soil. The average removal
efficiency was 98.8%.
• The system can effectively concentrate PCBs into a smaller
waste volume for offsite disposal.
• The treatment system's PCB removal efficiency was consis-
tently reproduced for all five batches treated during this demon-
stration.
For Further Information:
EPA Project Manager:
Mark Meckes
U.S. EPA Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
(513) 569-7348 FAX: (513) 569-7676
United States
Environmental Protection Agency
Center for Environmental Research information
Cincinnati, OH 45268
Official Business
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EPA
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EPA/540/MR-94/521
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