Hiroyuki HARA

Remediation of Soil Contaminated with Chlorinated Ethylenes
by Combined Use of Anaerobic Enrichment Culture and Iron Powder

Toshiya Komatsu@Shuji Himeno@Shoichi Fujita

Soil and groundwater contamination by chlorinated ethylenes, such as tetrachloroethylene (PCE) and trichloroethylene (TCE), are now serious problems in Japan. PCE and TCE can be decomposed into harmless products, ethylene and ethane by an anaerobic enrichment culture which we developed. Previous study showrd the effectiveness of using iron powder as the electron donor in the anaerobic bioremediation of PCE-contaminated soil by the enrichment culture, because hydrogen, which is the direct electron donor for dechlorination, is produced from iron powder under anaerobic conditions.
The purpose of this study is to examine various factors affecting the conversion of PCE and TCE in the combined remediation system of anaerobic enrichment culture and iron powder.
The experiment was conducted using six kinds of soil,and conducted according to the conditions from previous study.Efficient remediation was possible by holding pH in the optimum activity range of anaerobic enrichment culture. But in the case of acid soils, iron powder required for remediation increased. Consequently,we focused attention on alkaline colloidal iron,other iron material. As a result, The use of Colloidal iron seems to be particularly effective for the acid soil, because an increase of pH to neutral level occurs in the small amount of dose.