Anaerobic Biodegradation of Chlorinated Aliphatic Solvents

摘要

The anaerobic biodegradation of chlorinated aliphatic hydrocarbons (CAH) includingcarbontetrachloride (CT) and trichloroethylene (TCE) under various electron acceptorconditions was investigated using enrichment cultures developed from the anaerobicdigester sludge of Thibodaux sewage treatment plant. The results indicated that CT wasbiotransformed under sulfate-reducing, methanogenic, nitrate-reducing, iron-reducing,fermenting, and mixed electron acceptor conditions. However, the rates of CT removalvaried among the conditions studied. The fastest removal of CT (100% removal in 12days) was observed under mixed electron acceptor conditions followed in order bysulfate-reducing, methanogenic, fermenting, iron-reducing, and nitrate-reducingconditions. Similar results were observed for TCE. Under mixed electron acceptorconditions, the CT was converted to methyl chlorides, which was further metabolized.Under sulfate, iron, nitrate-reducing, and methanogenic conditions, the major metaboliteproduced from CT metabolism was chloroform (CF). Under fermenting conditions,methylene chloride was produced from CT metabolism. This study showed evidence forCT and TCE metabolism in a mixed microbial population system similar to anycontaminated field sites, where heterogeneous microbial population exists.