Evaluation of Hexavalent Chromium Treatment Using Iron-Chelate and Calcium Polysulfide in Conjunction with ISCO

摘要

Hexavalent chromium [Cr(VI)] is often found in contaminated groundwater along with a complex mixture of other pollutants due to its high solubility and stability over a wide range of pH conditions, which makes its remediation difficult. Chemical reduction/ fixation is among the most common remediation method for Cr(VI) treatment via reduction to trivalent chromium [Cr(III)], a less toxic and relatively immobile state of chromium. In-situ chemical oxidation (ISCO) has been widely used over the past decade for organic pollutant treatment; however, the resulting oxidizing conditions may be unfavorable for sequential Cr(VI) reduction. A series of bench-scale laboratory studies were performed on groundwater sample procured from a former industrial facility site impacted with both Cr(VI) and VOCs in an effort to find a compatible chemical oxidation/reduction solution that can address both the contaminants. ISCO using modified Fenton’s reagent (MFR) was being considered for this site to address the VOC/DNAPL contamination.