Constitutive dechlorination of chlorinated ethenes by a methanol degradingmethanogenic consortium

The ability of granular methanogenic sludge to dechlorinate chloroethenes w as investigated with unadapted sludge from an upflow anaerobic sludge blank et (UASB) reactor fed with methanol. The sludge degraded chlorinated ethene s, but the degradation rates were low. The addition of primary substrate wa s necessary to sustain dechlorination. The dechlorinating activity seemed t o be constitutively present in the anaerobic bacteria. Usually, one chlorin e atom was removed via reductive hydrogenolysis. Only trichloroethene (TCE) was converted to substantial amounts of vinylchloride (VC). 1,1-Dichloroet hene (1,1DCE) was observed to be an important intermediate in the dechlorin ation by unadapted granular sludge, although previously this compound had n ot been commonly observed. Furthermore, the dechlorination of 1,1DCE was fa ster than the dechlorination of the other chloroethenes. (C) 2001 Elsevier Science Ltd. All rights reserved.