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REDUCTIVE DETOXIFICATION AND IMMOBILIZATION OF CHROMATE PRESENT IN SOILS
Citation:
Khan*, F A. AND R W. Puls*. REDUCTIVE DETOXIFICATION AND IMMOBILIZATION OF CHROMATE PRESENT IN SOILS. HYDROLOGICAL SCIENCE AND TECHNOLOGY 15(1-4), (1999).
Description:
The in-situ permeable reactive barrier at the U.S. Coast Guard Air Support Center at Elizabeth City, North Carolina is very effective in remediating the contaminant plumes of TCE and chromate in the ground water, but it has limited effectiveness to attenuate chromate present as sorbed phases in the vadose zone. Manipulation of the oxidation-reduction (redox) status of a vadose zone is a viable approach for in-situ remediation of a redox-sensitive contaminant like chromate. It was hypothesized that by creating a reducing zone through introducing a reductant into the vadose zone, the soluble and sorbed Cr(VI) will be reduced and precipitated resulting in an immobile and less toxic Cr(III) mineral phase. Therefore, the objective of this study was to evaluate potential reductants and their effectiveness to reduce highly Cr(VI)-contaminated soil or sediment samples collected from the vadose zone beneath the plating facility. The reductants evaluated were sodium dithionite, 1-ascorbic acid, and hydroxylamine. These reductants reduced chromate present in soils/sediments, and each provided a unique geochemical environment. Sodium dithionite proved to be the most effective reductant to detoxify chromate present in the vadose zone materials.