科研之友
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摘要
Soil column tests were conducted to study the the remediation of chromate-contaminated groundwater with the reductive immobilization of in situ redox manipulation (ISRM) when polysulfide was chosen as the reductant and field-collected red soil and cinnamon were chosen as the packing material. The results indicated that both types of polysulfide-treated soils had good reductive properties to immobilize Cr(Ⅵ), although their reductive capacities varied to some extent. When 10 mg·L?1 Cr(Ⅵ) solution was continuously injected to the column packed with sulfidization treated red soil and cinnamon, the corresponding column breakthrough occurred at 38PV and 22PV, and their reductive capacities depleted at 218PV and 138PV, respectively. Significant changes in effluent pH and oxidation-reduction potential were observed in the soil sulfidization experiments and Cr(Ⅵ) reduction with sulfidization treated soil column. Further analysis indicated that the electronic utilization efficiencies of polysulfide-treated red and cinnamon soils were 23.0% and 24.8%, respectively. Based on column experiments, remediation of Cr(Ⅵ)-contaminated groundwater by ISRM with polysulfide reductant was an effective approach. Polysulfide addition can not only remove chromate in pore-water effectively, but also establish an effective reductive zone in porous media and perform a continuous field treatment of Cr(Ⅵ). The difference in dosages of polysulfide used in column tests and predicated by theory may arise from the complexity of soils. Thus, the actual remediation effect could be ensured by the application of field remediation with ISRM and reasonable addition of overdosed reductant.
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