不同氧化还原条件下氯乙烯的微生物脱氯

氯乙烯是土壤和地下水中存在的污染物,其去除的有效途径之一为微生物降解.本研究在温度20℃、氯乙烯初始浓度100μmol/L条件下,对不同氧化还原条件下四氯乙烯、cis-二氯乙烯及一氯乙烯的微生物降解进行了实验.结果表明,在铁还原和碳酸氢盐存在条件下,四氯乙烯以0.26/d和0.31/d的速率分别脱氯为三氯乙烯和cis-二氯乙烯.在脂肪酸存在条件下,四氯乙烯、cis-二氯乙烯和一氯乙烯均完全脱氯为乙烯,但后两者脱氯速率(0.04/d)明显低于前者(0.57/d).在反硝化、锰还原及硫还原条件下,不同取代氯乙烯降解均不明显.当环境温度降至12℃,脱氯菌活性降低,但氯乙烯完全脱氯还原过程仍可发生.

Dechlorination of Chlorinated Ethenes under Different Redox Conditions

Chlorinated ethenes are pollutants in contaminated soil and groundwater, and one of the efficient way to remove them is biodegradation. In this paper, the microbial breakdown of PCE, cis-DCE and VC with initial concentrations of 100 mumol/L were studied under different redox conditions at temperature 20 degrees C. The results showed that in the presence of ferric iron and carbon dioxide, PCE were dechlorinated to TCE (0.26/day) and cis-DCE (0.31/day), respectively. In the presence of fatty acids and without competition from inorganic electron acceptors, all the studied chlorinated compounds were completely dechlorinated to ethenes. However, the degradation rates of cis-DCE and VC (0.04/day) were much lower than that of PCE (0.57/day). Under denitrifying, manganese reducing and sulfate reducing conditions, no degradation of chloroethenes was observed. When the temperature was lowered to 12 degrees C, the activities of dechlorinating microbes were also reduced, nevertheless, the completely reductive dechlorination of chloroethenes still occurred.