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SEQUENTIAL ANAEROBIC DEGRADATION OF 2,4-DICHLOROPHENOL IN FRESHWATER SEDIMENTS
Citation:
Zhang, X. AND J. Wiegel. SEQUENTIAL ANAEROBIC DEGRADATION OF 2,4-DICHLOROPHENOL IN FRESHWATER SEDIMENTS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-94/294.
Description:
2,4-Dichlorophenol (2,4-DCP) was degraded anaerobically in freshwater lake sediments. rom observed intermediates in incubated sediment samples and from enrichment cultures, the following sequence of transformations was postulated. 2,4-DCP is dechlorinated to 4-chlorophenol (4-CP), 4-CP is dechlorinated to phenol, phenol is carboxylated to benzoate, and benzoate is degraded via acetate to methane and carbon dioxide. t least five different organisms are involved sequentially. he rate-limiting step was the transformation of 4-CP to phenol. ediment-free enrichment cultures were obtained that catalyzed only the dechlorination of 2,4-DCP, the carboxylation of phenol, and the degradation of benzoate, respectively. ow concentrations of 4-CP inhibited phenol and benzoate degradation. ransformation rates and maximum concentrations allowing degradation were determined in both freshly collected sediments and in adapted samples. t 31 degrees C, which was the optimal temperature for dechlorination, the average adaptation times for 2,4-DCP, 4-CP, phenol, and benzoate transformation were 7, 37, 11 and 2 days, respectively. he highest concentrations that still allowed the transformation of the compound in acclimated sediments were 3.1 mM 2,4-DCP, 3.1 mM, 4-CP, 13 mM phenol, and greater than 52 mM benzoate. he corresponding values were lower for sediments that had not been adapted for the transformation steps.