Soils washing system

After mixing for an appropriate time, clean soil particles and wash water containing the dissolved and suspended contaminants are separated. Separation techniques in soil-washing systems are similar to those applied in the mineral-processing industry.78 The most common separation techniques are as follows ... 

The big difference in application from the in situ flushing method is that this ex situ method can apply to soils with lower permeability, because soil is excavated and can be sufficiently washed. The following presents two ex situ soil washing processes for organic contaminants the BioGenesis soil cleaning process and the BioTrol soil washing system. 

FIGURE 18.16 BioTrol soil washing system process diagram. 

Castle, G, Brack, J., Sappington, D., and Erbaugh, M., 1985, Research and Development of a Soil Washing System for Use at Superfund Sites In Proceedings of the USEPA Sixth National Conference on Management of Uncontrolled Hazardous Waste Sites. Washington, D.C., pp. 452 155. 

T0131 Brice Environmental Services Corporation (BESCORP), Soil Washing System (BSWS)... 

According to the vendor, the SW-400 Soil Washing system has several advantages ... 

The BenCHEM soil washing system successfully treats inorganic mining ores and ore processing tailing wastes. The technology has also been successfully applied to petroleum-contaminated soils containing tetraethyl lead. 

The BioGenesis soil washing system also produces residual wastes that may require either additional treatment or off-site disposal. This factor can also affect treatment costs (D10256X, p. 30). 

The BioTrol soil washing system is a patented, water-based volume reduction process used to treat excavated soil. It separates slightly contaminated, coarse, washed soil particles from heavily contaminated fine soil particles. The process operates on the premise that (1) contaminants tend to be concentrated in the fine size fraction of soil (sUt, clay, and soil organic matter) and (2) contaminants associated with the coarse soil fraction (sand and gravel) are primarily surficial. The BioTrol soil washing system can be used to treat soils contaminated with petroleum hydrocarbons, pesticides, polychlorinated biphenyls (PCBs), various industrial chemicals, and metals. 

BioTrol soil washing system costs for the MacGilhs and Gibbs Superfund site in New Brighton, Minnesota, were examined on both an integrated and a unit process basis. Costs for the demonstration study were extrapolated to full-scale treatment of the wood preserving site. The extrapolation included both operating costs and capital costs amortized over an assumed 10-year equipment life span. Costs were estimated in 1991 dollars. 

If all three technologies [soil washing (SW), slurry bioreactor (SBR), and BioTrol aqueous treatment system (BATS)] are used, the estimated cost of a commercial-scale soil washing system is 168/ton ( 185/metric ton). Incineration of woody material removed during washing accounts for 76% of the cost (D110690, p. 43). 

The BESCORP Soil Washing System (BSWS) is a water-based unit for the volume reduction of coarse/sandy soils contaminated with lead or other heavy metals. It uses a combination of trommel agitation, attrition scrubbing, high-pressure washing, and separation by particle size and density to remove heavy metals and heavy-metal compounds from soil. 

The soil washing system treats soil and can potentially treat nonmunicipal sludge, solids (e.g., slag), and natural sediment. The Divesco system cannot treat asphalt and tars. 

The cost of the Divesco soil washing system ranges from 50 to 65 per ton of waste treated (D10161R, p. 8). 

The aqueous soil washing system is used to classify the particles into a coarse and fine fraction. The coarse fraction is cleaned by the use of heat, chemicals, and mechanical energy. This material can be returned to the site as clean backfill. The fine fraction is thickened and sent to the solvent extraction unit. 

EnRem has developed a soil washing system that recovers hydrocarbons for reuse. The unit uses a patented chemical, EnRem-17. All information is from the vendor and has not been independently verified. 

The TRUclean soil washing system is a patented, ex situ modular process that uses soil washing, size fractionation, and gravimetric separation techniques to remediate soils contaminated with radionuclides and heavy metals. The technology developer, Lockheed Martin Corporation, claims... 

The Metcalf Eddy HYDRO-SEP soil washing system is an ex situ, water-based technology that separates contaminants from soil matrices. The HYDRO-SEP modular system uses screening and hydraulic classification processes to separate uncontaminated soil particles from a contaminated mixture. 

Soil washing system (possibly mixers, washers, screens, conveyors, etc.)... 

The Snrbec soil washing technology is commercially available. It has been nsed in The Netherlands for more than 10 years and has treated over 600,000 tons of contaminated soil. According to the vendor, the soil washing system has several advantages ... 

According to the vendor, a pilot-scale soil washing system was used in Duphar, The Netherlands, to treat 50 tons of soil contaminated with lindane. The vendor states that the unit cost of the demonstration was 50 per ton (D21365A, p. 9). 

TABLE 1 Vendor-Estimated Operational Costs for a 20-yd /hr Soil Washing System... 

The vendor has determined that the operating costs for the Terra Wash technology depend upon the nature of the soil matrix, the contaminants treated, the rate of treatment, system maintenance requirements, and the surfactant-to-water ratio. Table 1 shows a set of vendor-estimated operational costs for a 20-yd /hr soil washing system. The vendor has also provided estimates for larger capacity systems however, these larger systems have not yet been built (D168290, pp. 11-30 D21392D, p. 1). 

After the completion of remediation activities, 1000 to 4000 gal of flnids remain in the soil washing system. This waste requires disposal, which may cost up to l/gal (D21392D, p. 2). 

The Trigon Group, L.L.C., soil washing system is commercially available. 

The TVIES, Inc., soil washing system has a cost range of 30 to 100/yd for hydrocarbon remediation, and a cost range of 30 to 150/yd for metals remediation. The remediation of nuclear materials can cost up to 600/yd if the soil has been packed in drums, because drum handling alone is sometimes more expensive than soil remediation (D10352W, p. 2). 

Soil washing system (water-based volume reduction) at MacGillis Gibbs Superfund site in Minnesota (Cheremisinoff, 1989) PAHs, PCBs, and PCP BioTrol, Inc., Minnesota... 

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