S-EPA
United States
Environmental Protection
Agency
EPA/540/MR-92/075
October 1992
SUPERFUND INNOVATIVE
TECHNOLOGY EVALUATION
Demonstration Bulletin
Soil/Sediment Washing System
Bergmann USA
Technology Description: The Bergmann USA Soil/Sediment
Washing System is a waste minimization technique designed to
separate or "partition" soils and sediments by grain size and
density. In this water-based volume reduction process, hazard-
ous contaminants are concentrated into a small residual portion
of the original volume using physical and chemical methods. The
theory of operation is based upon the hypothesis that most of the
contaminants of interest in the sediment are partitioned or con-
centrated into two fractions: organic materials (i.e., leaves, roots,
twigs, bark, etc.) and fine particles ("fines"), and that contamina-
tion of the larger, granular particle fraction (clean sand and
larger) is small. This process may then minimize the amount of
waste since the volume of contaminated material requiring further
treatment may be greatly reduced by virtue of isolating and
concentrating the contaminants.
Figure 1 presents a schematic flow diagram of the Bergmann
USA Soil/Sediment Washing System. Solid material is trans-
ported to and from the system by a series of conveyor belts. At
various locations, the soil encounters water that passes through
the system in a countercurrent fashion. Multiple pieces of equip-
ment are used to separate the resulting slurries into fractions
based on their grain size and density. A brief description of this
equipment follows.
A trommel unit separates out fractions coarser than 6 mm and
allows the remainder of the material to proceed through the
system for further separation by a series of three cyclone separa-
tors. A dense media separator (DMS), or hydrosizer, facilitates
the removal of light organic particles (sp. gr. <1.6) from the sand
fraction. Removal of these organics is important as this fraction of
material generally acts as a primary host to contaminants. An
attrition scrubbing machine is used to remove surficial contami-
nants from the sand grains. Reagents such as surfactants or pH
modifiers may be added to the feed of the attrition cell. A parti-
tioned dewatering screen recovers both the sand fraction and the
organic fraction from their respective slurries. A clarifier, with the
aid of polymer flocculents, is used to separate out the fines.
Waste Applicability: This technology is suitable for land-
based soils as well as river and harbor sediments containing no
more than 40% sift and clay material; the solid organic content
should not exceed 20% by volume. The medium to be separated
may be contaminated with both organic and inorganic constitu-
ents.
Demonstration Results: A demonstration of a Bergmann
USA pilot-scale (5 ton/hr) Soil/Sediment Washing System has
been performed under the Superfund Innovative Technology Evalu-
ation (SITE) Program. The demonstration occurred in late May/
early June 1991 at the U.S. Army Corps of Engineers (USAGE)
Confined Disposal Facility (CDF), a man-made island in the
Saginaw Bay of Lake Huron near Essexville, Michigan.
During the Demonstration Test, the Bergmann USA Soil/Sedi-
ment Washing System treated sediments contaminated with poly-
chlorinated biphenyls (PCBs) and heavy metals that had been
previously dredged from the Saginaw River and stockpiled on the
CDF. The Demonstration Test results indicate that the Soil/
Sediment Washing System can effectively isolate and concen-
trate the PCB contamination into the organic fraction and the
fines. Levels of metals contamination were also beneficially al-
tered from the feed stream to the output streams. The effective-
ness of the Soil/Sediment Washing System on the inorganic
compounds met or exceeded its performance for PCB contami-
nation.
A 5-day test of continuous operation 8 hr/day with 100% on-line
efficiency of the Bergmann USA Soil/Sediment Washing System
using the dredged sediments from the Saginaw River gave the
following results:
Approximately 71% of the total <45-u. particle output from the
Soil/Sediment Washing System was found in the fines.
Less than approximately 20% of the total <45-^ particle
fraction was found in the clean sand.
The distribution of concentrations of the PCBs in the input
and output streams were as follows:
Input Sediment = 1.6 mg/kg
Output Sand = 0.20 mg/kg
Output Organics = 11 mg/kg
Output Fines = 4.4 mg/kg
The metals of concern were concentrated in the same man-
ner as the PCBs.
Ť The clean sand output consisted of approximately 82% of
the input sediment.
A Technology Evaluation Report and an Applications Analysis
Report describing the complete Demonstration will be available in
the Fall of 1993.
iŁg> Printed on Recycled Paper
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For Further Information:
EPA Project Manager:
Jack Hubbard
U.S. EPA Risk Reduction Engineering Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
(513) 569-7507
Trommel Spray
(from within system)
Dredged ,"
Material
Feed ~
Key:
* Water Line
~*"" Process Flow
\l Separator
Velmet
Rotary
Screen
*. Organics >0.5mm
Surnpi
Dense
Media
Separator
(Hydrosizer)
Fines
FIgttro 1. Schematic flow diagram of Bergmann USA Soil/Sediment Washing System.
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
BULK RATE
POSTAGE & FEES PAID
EPA
PERMIT No. G-35
EPA/S40/MR-92/075
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