Bacterial removal of toxic phenols from an industrial effluent

Chlorinated phenols, widely used in industries, are of growing concern owing to their high toxicity, carcinogenicity and wide distribution in industrial wastes. In the present study, one Pseudomonas isolate, identified as Pseudomonas fluorescens, was obtained using the enrichment process with 2,4,6-trichlorophenol (2,4,6-TCP) as a sole carbon source. This isolate was found to be able to degrade various highly chlorinated phenolic compounds such as pentachlorophenol, 2,4,5-TCP, 2,4,6-TCP as well as phenol, 2,4-dibromophenol and 2,4-dichlorophenol (2,4-DCP). The ability of P. fluorescens isolate to remove phenol from a resin producing industrial effluent was tested by scanning the spectrum with a UV-VIS spectrophotometer. The results indicated that this isolate metabolized phenol in the meta-pathway. The optimal phenol degradation conditions of P. fluorescens isolate were at pH 7 and 30oC. At the 480 mg/l of phenol concentration, the highest specific degradation rate of was observed. Further increases in phenol concentration slowed down the degradation ability of the isolate. However, P. fluorescens isolate still has the ability of degrading phenol at the concentration of 3.2 g/L. The supplementation of 1% glucose stimulated the growth of P. fluorescens isolate and enhanced the ability to utilize phenol from the effluent sample. GC-MS results show that 85.4% of phenol in the effluent sample was metabolized after 40 days. In conclusion, P. fluorescens isolated in this study has the ability of utilizing various chlorophenolic compounds and demonstrates its potentials of degrading high concentration of phenol in industrial effluents.