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

本研究旨在建立铁粉还原性脱氯与厌氧微生物生物降解相结合的复合系统，修复土壤中含氯有机物污染。主要研究成果如下：对金属铁粉对氯化有机化合物如TCE的还原脱氯反应进行了动力学分析，阐明了反应过程的细节。提出了铁粉与土壤混合处理污染物的方法。当反应渗透墙安装在污染源区域时，反应渗透墙下游地下水中氯代有机物的浓度急剧下降。作为除铁粉以外的还原剂，在对硫铁矿等硫化矿物的利用进行考察时，发现在黄铁矿表面形成了噻吩衍生物和单质硫作为反应产物。同时，气相中未检出产物，液相中检出氯离子。在厌氧条件下，利用富集培养系统对TCE进行了间歇处理。在培养液中加入甲醇或EDC，观察了TCE对乙烯的脱氯作用。在含氯有机化合物的污染源区域混合并填充铁粉，在污染物浓度较低的污染源区域周围进行微生物处理。与每个过程独立进行的情况相比，这种混合系统非常有效地去除了污染物。

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.