DEGRADATION OF CHLOROPHENOLS BY ALCALIGENES-EUTROPHUS JMP134(PJP4) INBLEACHED KRAFT MILL EFFLUENT

The ability of Alcaligenes eutrophus JMP134(pJP4) to degrade 2,4-dichl orophenoxyacetic acid, 2,4,6-trichlorophenol, and other chlorophenols in a bleached kraft mill effluent was studied. The efficiency of degra dation and the survival of strain JMP134 and indigenous microorganisms in short-term batch or long-term semicontinuous incubations performed in microcosms were assessed. After 6 days of incubation, 2,4-dichloro phenoxyacetate (400 ppm) or 2,il,6-trichlorophenol (40 to 100 ppm) wer e extensively degraded (70 to 100%). In short-term batch incubations, indigenous microorganisms were unable to degrade such of compounds. De gradation of 2,4,6-trichlorophenol by strain JMP134 was significantly lower at 200 to 400 ppm of compound. This strain was also able to degr ade 2,4-dichlorophenoxyacetate, 2,4,6-trichlorophenol, 4-chlorophenol, and 2,4,5-trichlorophenol when bleached Kraft mill effluent was amend ed with mixtures of these compounds. On the other hand, the chlorophen ol concentration and the indigenous microorganisms inhibited the growt h and survival of the strain in short-term incubations. In long-term ( >1-month) incubations, strain JMP134 was unable to maintain a large, s table population, although extensive 2,4,6-trichlorophenol degradation was still observed. The latter is probably due to acclimation of the indigenous microorganisms to degrade 2,4,6-trichlorophenol. Acclimatio n was observed only in long-term, semicontinuous microcosms.