Hybrid System for in-situ Remediation of Contaminated Soil by Chlorinated Organic Compounds

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The purpose of this study was to establish the hybrid system combined reductive dechlorination by iron powder and biodegradation with anaerobic microorganisms for the remediation of the soil contaminated with chlorinated organic compounds. Main research results are as follows.1.On the reductive dechlorination of the chlorinated organic compounds such as TCE by the metallic iron powder, the details of the reaction palhway was clarified by the kinetic analysis. The mixing method of iron powder to the soil to treat the contaminant efficient was developed.2.The concentration of chlorinated organic compounds in the groundwater drastically decreased in the downstream of the reactive permeable wall, when the wall was installed in the contaminant source area.3.As a reducing agent except for iron powder, it was detected that thiophene derivatives and elemental sulfur had been formed as reaction product in the pyrite surface, when the utilization of sulfide mineral such as the pyrite was examined. At the same time, no product detected in the vapor phase, though chloride ion was detected in liquid phase.4.The batch treatment at the anaerobic condition using the enrichment culture system for decomposing TCE was carried out. The dechlorination of TCE to the ethene was observed, when methanol or the EDC was added to culture solution.5.Iron powder was mixed and filled in the contaminant source area of chlorinated organic compounds, and microbial treatment was applied around the source area where the concentration of the contaminant was relatively lower level. The contaminant was very efficiently removed by this hybrid system in comparison with the case in which each process was independently carried out.