ANAEROBIC DECHLORINATION OF TRICHLOROETHYLENE (TCE) TO ETHYLENE USINGCOMPLEX ORGANIC MATERIALS

Reductive dechlorination of trichloroethylene (TCE) io ethylene was su pported by complex organic matter such as cane molasses and ligno-cell ulosic materials as a substrate and electron donor under methanogenic conditions. The studies were performed with an anaerobic dechlorinatin g, methanogenic microbial consortium at 20-22 degrees C. A high molar ratio between methane and ethylene (158 mol/mol) was observed during r apid dechlorination of TCE with cane molasses as a substrate. Three li gnocellulosic materials (corn cobs, hard wood chips and newsprint) sup ported dechlorination of TCE to ethylene. After 140 days of incubation , the molar ratio between methane and ethylene was 36, 29 and 22 mmol/ mmol for corn cobs, wood chips and newsprint, respectively. The rates of dechlorination and methanogenes were relatively rapid during the fi rst 60 days. The efficiency of COD and electrons used for dechlorinati on ranged from 0.3-0.5% for cane molasses to 2.0-3.5% for ligno-cellul osic materials. Methanogenesis was more prevalent reaction than dechlo rination during the studies, bur the fraction of electron donors and c hemical oxygen demand (COD) used for dechlorination was increased when biodegradability of the ligno-cellulosic materials slowed. The comple x organic matter can be used as a cost-effective substrate for anaerob ic biotreatment of chlorinated ethylenes. (C) 1998 Elsevier Science Lt d. All rights reserved.