BERGMANN, A DIVISION OF LINATEX, INC.

(Soil and Sediment Washing)

TECHNOLOGY DESCRIPTION:

The soil and sediment washing technology developed by Bergmann, A Division of Linatex, Inc.'s, (Bergman), separates contaminated particles by density and grain size (see photograph below). The technology operates on the hypothesis that most contamination is concentrated in the fine particle fraction (less than 45 microns [m]) and that contamination of larger particles is generally not extensive.

Bergmann Soil and Sediment Washing

After contaminated soil is screened to remove coarse rock and debris, water and chemical additives such as surfactants, acids, bases, and chelators are added to the medium to produce a slurry feed. The slurry feed flows to an attrition scrubbing machine. A rotary trommel screen, dense media separators, cyclone separators, and other equipment create mechanical and fluid shear stress, removing contaminated silts and clays from granular soil particles.

Different separation processes create the following four output streams: (1) coarse clean fraction; (2) enriched fine fraction; (3) separated contaminated humic materials; and (4) process wash water. The coarse clean fraction particles, which measure greater than 45 m (greater than 325 mesh) each, can be used as backfill or recycled for concrete, masonry, or asphalt sand application. The enriched fine fraction particles, measuring less than 45 m each are prepared for subsequent treatment, immobilization, destruction, or regulated disposal. Separated contaminated humic materials (leaves, twigs, roots, grasses, wood chips) are dewatered and require subsequent treatment or disposal. Upflow classification and separation, also known as elutriation, separates light contaminated materials such as leaves, twigs, roots, or wood chips. The process wash water is treated by flocculation and sedimentation, oil-water separation, or dissolved air flotation to remove solubilized heavy metal and emulsified organic fractions. The treated process wash water is then returned to the plant for reuse.

WASTE APPLICABILITY:

This technology is suitable for treating soils and sediment contaminated with organics, including polychlorinated biphenyls (PCB), creosote, fuel residues, and heavy petroleum; and heavy metals, including cadmium, chromium, lead, arsenic, copper, cyanides, mercury, nickel, radionuclides, and zinc.

STATUS:

This technology was accepted into the SITE Demonstration Program in winter 1991. It was demonstrated in Toronto, Ontario, Canada in April 1992 as part of the Toronto Harbour Commission (THC) soil recycling process. For further information on the THC process, including demonstration results, refer to the THC profile in the Demonstration Program section (completed projects). The technology was also demonstrated in May 1992 at the Saginaw Bay Confined Disposal Facility in Saginaw, Michigan. The Applications Analysis Report (EPA/540/AR-92/075) and the Demonstration Bulletin (EPA/540/MR-92/075) are available from EPA.

Since 1981, Bergmann has provided 31 commercial systems, treating up to 350 tons per hour, at contaminated waste sites.

DEMONSTRATION RESULTS:

Demonstration results indicate that the soil and sediment washing system can effectively isolate and concentrate PCB contamination into the organic fractions and the fines. Levels of metals contamination were also beneficially altered from the feed stream to the output streams. The effectiveness of the soil and sediment washing system on the inorganic compounds met or exceeded its performance for PCB contamination.

During a 5-day test in May 1992, the Bergmann soil and sediment washing system experienced no downtime as it operated for 8 hours per day to treat dredged sediments from the Saginaw River.

The demonstration provided the following results:

• Approximately 71 percent of the particles smaller than 45-m in the input sediment was apportioned to the enriched fine stream.
• Less than 20 percent of the particles smaller than 45-m in the input sediment was apportioned to the coarse clean fraction.
• The distribution of the concentrations of PCBs in the input and output streams were as follows:
  Input sediment = 1.6 milligrams per kilogram (mg/kg)
  Output coarse clean fraction = 0.20 mg/kg
  Output humic materials = 11 mg/kg
  Output enriched fines = 4.4 mg/kg
• The heavy metals were concentrated in the same manner as the PCBs.
• The coarse clean sand consisted of approximately 82 percent of the input sediment.

FOR FURTHER INFORMATION:

EPA PROJECT MANAGER:
Jack Hubbard
U.S. EPA
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7507
Fax: 513-569-7620

TECHNOLOGY DEVELOPER CONTACT:
George Jones
Bergmann, A Division of Linatex, Inc.
1550 Airport Road
Gallatin, TN 37066-3739
615-230-2217
Fax: 615-452-5525