United States
Environmental Protection
Agency
EPA/540/MR-92/079
December 1992
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION \
Demonstration Bulletin
The Basic Extractive Sludge Treatment (B.E.S.T.®)
Resources Conservation Company (RCC)
Technology Description: The Basic Extractive Sludge Treat-
ment (B.E.S.T.®) process is a solvent extraction system that
separates organic contaminants from sludges, soils, and sedi-
ments. The primary distinguishing feature of the process is the
extraction agent, triethylamine.
The key to the success of triethylamine extraction is the property
of inverse miscibility. At temperatures below 60°F, triethylamine
is miscible with water; above 60°F, triethylamine and water are
only slightly miscible. Therefore, by utilizing solvent chilled below
60°F, solids can be dewatered while simultaneously extracting
organic contaminants. This is referred to as a "cold extraction".
Afterwards, the remaining organic contaminants can be removed
at temperatures ranging from 70 to 1608F and higher. These are
referred to as "warm" and "hot" extractions, respectively.
The B.E.S.T.® process operates as follows. Contaminated mate-
rial screened to less than 1/2 inch diameter (1/8 inch
for this demonstration) is added to a refrigerated premix tank with
a predetermined volume of 50 percent sodium hydroxide. After
the tank is sealed and purged with nitrogen, chilled solvent is
added. The chilled mixture is agitated, and then allowed to
settle. After this cold extraction is completed, the resuj|ng__
solution of solvated oil, water, and solvent is decantedlrbm the
solids and centrifuged. The solvent and water are removed from
the solvent/water/oil mixture by evaporation and condensation of
the solvent and water.
Cold extractions are repeated as additional feed is added to the
premix tank so that enough solids are accumulated to warrant
subsequent extraction cycles. Solids with high moisture contents
may require more than one cold extraction. For this demonstra-
tion, a sediment containing 41% moisture required two cold
extractions.
Once a sufficient volume of moisture-free solids is accumulated,
it is transferred to a steam jacketed extractor/dryer. Warm
triethylamine is added to the solids. The mixture is heated,
agitated, settled, and decanted. This process can also be re-
peated. These warm and hot extractions result in separation of
the organics not removed during the initial cold extraction.
The B.E.S.T.® solvent extraction process is illustrated in Figure 1.
As illustrated, high oil and/or water content material such as
Primary Extraction/
Dewatering
Solvent Recovery
Filter Cake
Secondary Extraction/
Solids Drying
Steam
Clean Soilds
Product
^ Solvent Evaporator
Oil
Product
Chiller
Figure 1. Simplified diagram of the RCC B.E.S. T. solvent extraction process.
Product
Water Receiver
Printed on Recycled Paper
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sludge is placed initially in a premix tank where cold extractions
are performed. Although the total number of cold and hot extrac-
tion cycles required for a particular feedstock may vary, bench-
scale tests aid in the determination of process requirements.
The solids remaining in the extractor/dryer contain triethylamine
following decanting. After a small amount of caustic is added for
pH control, the solvent is volatilized by heating with the steam
jacket. Steam Is also injected into the solids near the end of the
drying cycle to drive off residual solvent and to add moisture to
reduce dust problems. The products from the fully run process
are 1) product solids 2) product water and 3) concentrated oil
containing the organic contaminants. The recovered oil fraction
can be dechlorinated or incinerated to destroy the organics. The
triethylamine is recovered and reused in further extractions.
Waste Applicability: This process is designed to treat slud-
ges, soils, and sediments contaminated with organic compounds.
Polynuclear aromatic hydrocarbons (PAHs) and polychlorinated
biphenyls (PCBs) were the organics of interest during the demon-
stration.
Demonstration Results: The demonstration of RCC's
B.E.S.T.* pilot plant was conducted in cooperation with the Great
Lakes National Program Office and the U.S. Army Corps of
Engineers. The testing took place between July 1 and July 22,
1992 at a location adjacent to the Grand Calumet River in Gary,
IN. The material treated during the demonstration was river
bottom sediment collected from two separate locations along the
Grand Calumet River.
Figure 2 is a regional map showing the approximate sample
locations. These core sample locations were chosen so that a
variation in contaminant concentration (including oil percentage)
could be evaluated in regard to treatment applicability.
The B.E.S.T.® demonstration consisted of two separate tests, one
for each sediment type. Each test consisted of two phases;
Phase I involved determination of optimum process variables from
results of three runs and Phase II consisted of two additional runs
at the determined optimum conditions (for a total of three optimum
runs.)
Sediment A contained 41% moisture, 6,900 mg/kg oil and grease,
12 mg/kg PCBs and 550 mg/kg PAHs. The process removed
greater than 98% of the oil and grease, 99% of the PCBs and
Chicago
Indiana
Harbor
3 Miles A
North
Lake Michigan
Grand Calumet River Sediment A Gary, IN
Figure 2. Regional location map.
greater than 96% of the PAHs. Sediment B contained 64%
moisture, 127,000 mg/kg oil and grease, 430 mg/kg PCBs and
73,000 mg/kg PAHs. The process removed greater than 98% of
the oil and grease and greater than 99% of the PCBs and PAHs.
The residual solvent in the product solids, product water, and
product oil (Sediment B) was 103 mg/kg, less than 1
mg/l, and 730 mg/kg, respectively.
A Technical Evaluation Report and an Applications Analysis
Report describing the complete demonstration will be available in
the summer of 1993.
For Further Information:
EPA Project Manager:
Mark Meckes
U.S. Environmental Protection Agency
Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7348
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
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EPA
PERMIT No. G-35
EPA/540/MR-92/079
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