Superfund Innovative Technology Evaluation (SITE)
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of Organics and Stabilization of Metals in Soils
The Center for Hazardous Materials Research (CHMR), through a Cooperative Agreement with the U.S. Environ-mental Protection Agency's National Risk Management Research Laboratory, conducted a laboratory evaluation of the Sulchem Process for treatment of soils contaminated with organic hydro-carbons and heavy metals. The Sulchem Process mixes the material being treated with elemental sulfur at elevated temperatures in an inert reactor system. Organic hydrocarbons react with the sulfur to form an inert fine solid of carbon and sulfur, hydrogen sulfide gas, and modest a mounts of carbon disulfide. Heavy metals react to form sulfides or sulfidecoated particles which are less soluble. The acid gases formed may be scrubbed or treated to recover elemental sulfur using an auxiliary process unit. At processing temperatures of 2500 to 35O0C, destruction and removal efficiencies for aromatic hydrocarbons from phenanthrene to benzopyrene were all in excess of 99%. Using the EPA Method 1311, Toxicity Characteristic Leaching Procedure (TCLP), cadmium, copper, lead, nickel, and zinc were significantly reduced following treatment of the soil by the Sulchem process. Copper TCLP values were reduced most effectively; lead was reduced below regulatory targets when concentrations in the original soil were below about 10,000 ppm. Cadmium was reduced below TCLP limits when the concentration in the original soil was below several thousand ppm. Process economics for remedial soil treatment were estimated to be in the range of $105 to $181/ton depending on the size of the site and the processing rate.