Treatment of soil contaminated with Cr(VI) by soil washing and bioremediation.

Radian Corporation has developed a process for treating hexavalent chromium contaminated soils that involves: soil washing using an alkaline extractant; biological reduction of Cr(VI) to Cr(III) in the soil wash effluent; and separation of Cr(III) from the biologically treated effluent. Biological treatment has been demonstrated for immobilised cells (fixed-film) in fluidised bed bioreactors and suspended cells in slurry bioreactors for Cr(VI) levels ranging from 30-600 mg/l which have been reduced to non-detectable levels (less than 0.05 mg/l). The resulting Cr(III) effluent was chemically treated to precipitate chromium hydroxide for removal by physical separation.
Radian Corporation has developed a process for treating hexavalent chromium contaminated soils that involves: soil washing using an alkaline extractant; biological reduction of Cr(VI) to Cr(III) in the soil wash effluent; and separation of Cr(III) from the biologically treated effluent. Biological treatment has been demonstrated for immobilised cells (fixed-film) in fluidised bed bioreactors and suspended cells in slurry bioreactors for Cr(VI) levels ranging from 30-600 mg/l which have been reduced to non-detectable levels (less than 0.05 mg/l). The resulting Cr(III) effluent was chemically treated to precipitate chromium hydroxide for removal by physical separation.