title: Calcium polysulfide remediation of hexavalent chromium contamination from chromite ore processing residue.
abstract: Past disposal of high-lime chromite ore processing residue (COPR) from a chemical works in S.E. Glasgow, UK, has led to continuing release of toxic and carcinogenic hexavalent chromium (Cr(VI)) to groundwaters which are highly contaminated with Cr(VI)O4(2-). Traditional methods of remediating Cr(VI)-contaminated land, e.g. using ferrous sulfate and organic matter, have had limited success in converting Cr(VI) to less harmful and insoluble Cr(III). This paper describes the first application of calcium polysulfide (CaS(x)) to the remediation of contaminated groundwater and high-lime COPR in a series of laboratory experiments, which have demonstrated the effectiveness of the treatment in quantitatively and rapidly reducing Cr(VI) to Cr(III) over the pH range (8-12.5) typically found at the sites. Cr(III)-organic complexes, present in groundwater at one location, were also effectively precipitated upon treatment with CaS(x). The potential for large-scale use of CaS(x) in the remediation of Cr(VI) from COPR is also discussed.
authors.affiliation: School of GeoSciences, Joseph Black Building, University of Edinburgh, Edinburgh EH9 3JJ, Scotland, UK. margaret.graham@ed.ac.uk
authors.forename: Margaret C
authors.initials: MC
authors.lastname: Graham
authors.forename: John G
authors.initials: JG
authors.lastname: Farmer
authors.forename: Peter
authors.initials: P
authors.lastname: Anderson
authors.forename: Edward
authors.initials: E
authors.lastname: Paterson
authors.forename: Stephen
authors.initials: S
authors.lastname: Hillier
authors.forename: David G
authors.initials: DG
authors.lastname: Lumsdon
authors.forename: Richard J F
authors.initials: RJ
authors.lastname: Bewley
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D002274:Carcinogens, Environmental / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D007220:Industrial Waste / Q000032:analysis*; D008669:Metallurgy; D012606:Scotland; D013440:Sulfides / Q000737:chemistry*; D013885:Thiosulfates / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000032:analysis; D014881:Water Supply / Q000032:analysis
chemical_list: D017610:Calcium Compounds; D002274:Carcinogens, Environmental; D007220:Industrial Waste; D013440:Sulfides; D013885:Thiosulfates; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion; C033907:calcium sulfide