Fixation and stabilization of chromium in contaminated materials

摘要

A highly flexible multi-step treatment technology for chemical fixation and stabilization of leachable chromium, particularly hexavalent chrome, in contaminated soils, solid wastes, concrete, sludge, sand and gravel and waste waters is disclosed. The process comprises reducing hexavalent chromium to chromous (Cr2+) and chromic (Cr3+) forms in the presence of water under alkaline conditions and fixing the reduced chromium forms with phosphate. The process reduces Toxicity Characteristic Leaching Procedure chromium levels below the regulatory threshold of 5 mg/l as required by the USEPA.