United States
Environmental Protection
Agency
EPA/540/M5-91/003
July 1991
&EPA
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration Bulletin
Soil Washing System
BioTrol, Inc.
Technology Description: The three component technologies
of the BioTrol Soil Washing System (BSWS), tested in the SITE
demonstration were a Soil Washer (SW), an Aqueous Treatment
System (ATS), and a Slurry Bio-Reactor (SBR). The Soil Washer
operates on the principle that a significant fraction of the chemicals
in a contaminated soil are either physically or chemically bound to
the silt, clay or humic particles, and removal of these fine particles
leaves the bulk of the soil (mostly sand) relatively clean. Excavated
soils are screened to remove debris and mixed with waterto form a
slurry. The slurry is subjected to a series of intensive scrubbing and
physical classification steps to scour the contaminants and silt and
clay fines from the sand particles. The washed sand is separated
from theslurry, and the remaining contaminated fines can be treated
in the SBR. Contaminated process water from the Soil Washer can
be sent to the ATS to remove organics. Figure 1 is a simplified flow
diagram of the Soil Washer, the ATS, and the SBR.
The ATS is a microbiological system for degrading toxic organics in
contaminated water. It consists of a multi-cell, submerged packed-
bed reactor where naturally occurring microbes along with an
inoculum of a bacterium species specific to the chemical are allowed
to grow on a plastic support material. Process water from the Soil
Washer is pumped to the system where the pH is adjusted and
nutrients are added to optimize the performance of the microbes.
The waste stream is then passed through the reactor where the
combination of microbes rapidly degrades the penta-chlorophenol
(penta) and polynuclear aromatic hydrocarbons. (PAHs) into carbon
dioxide, water, and inorganicchloride, which are harmless products.
The SBR is a three stage microbiological system for treating
degraclable organiccontaminants associated with fine soil particles.
The equipment for the system is an EIMCO BioLift™ reactor
manufactured by the EIMCO Process Equipment Company. BioTrol
Contaminated
Water *
Contaminated
Sift/Clay **
Aqueous
Treatmerit
System (ATS)
Slurry
Bio-Reactor
(SBR)
Clean
Water
Can be treated by a variety of methods.
* Can be treated also by incineration, stabilization or
disposed off-site.
Figure 1. Flow diagram of the BioTrol soil washing system.
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uses the reactor to remove contamination from sift and clay soil
fractions. The system consists of three upright, continuously-stirred
reactors in series. The silt and clay slurry enters the first reactor
where the degradation of organic contaminants by the indigenous
and inoculated mterobial populations begins. As the slurry flows to
each successive reactor, the contaminants are further degraded to
inorganic products. However, the contaminated residual products
from soil washing can be treated by other methods than the ATS and
the SBR.
Waste Applicability: This technology was initially developed to
treat soils contaminated with oil, penta, and creosote (PAHs) from
wood preserving sites. It is also expected to be applicable to soils
contaminated with petroleum hydrocarbons and pesticides.
Demonstration Results: The SITE demonstration of the soil
washing technology took place from September 25 to October 27,
1989 at the MacGillis & Gibbs superfund site in New Brighton,
Minnesota. The Soil Washer used in the demonstration was a pilot
scale unit with a treatment capacity of 500 to 1,000 Ib/hr. The Soil
Washer was operated continuously for two days on a soil contami-
nated with low levels of penla (about 130 mg/kg) and seven days on
a high penta level soil (about 680 mg/kg). All process waterfrom soil
washing was treated in the ATS and recycled back to the Soil
Washer. A portion of the fine particle slurry from the high penta soil
washing test was treated in the pilot scale SBR. Table 1 summarizes
the test results:
Table 1. Demonstration Results
High Cone. Soil Test
Low Cone. Soil Test
Soil Washer
ATS
SBR*
Test
Contaminant
Penta
PAH
(carcinogenic)
PAH
(non-carcinogenic)
Penta
PAH
Penta
PAH
(carcinogenic)
(non-carcinogenic)
Influent
Cone.
mg/kg
680
58
300
mg/l
44
N/D1
3500
800
280
Effluent %Reduction
Cone.
mg/kg
87
6.5
37
mg/l
3
N/D1
280
140
7.3
87
89
88
94
92
82
97
Influent
Cone.
mg/kg
130
17
230
mg/l
15
N/D1
Effluent
Cone.
mg/kg
14
2.3
33
mg/l
1.3
N/D1
%Reduction
89
86
86
91
1N/D: Not Detected.
'Results for the SBR are for the solid fraction (after filtration) of the slurry only. Performance results are maximum
no steady- state performance was achieved during the test.
values observed as
For Further Information:
EPA Project Manager:
Mary K. Stinson
Risk Reduction Engineering Laboratory, USEPA
Woodbridge Avenue
Edison, New Jersey 08837
Phone: (201)321-6683 FTS:340-6683
Technology Developer Contact:
Dennis Chilcote
BioTrol, Inc.
11 Peavey Road
Chaska, Minnesota 55318
Phone:(612)448-2515
United States
Environmental Protection
Agency
Center for Environmental
Research Information
Cincinnati, OH 45268
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
Official Business
Penalty for Private Use $300
EPA/540/M5-91/003
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