A GAC biofilm reactor for the continuous degradation of 4-chlorophenol: treatment efficiency and microbial analysis

Using a continuous enrichment technique, a bacterial consortium capable of degrading 4-chlorophenol (4-CP) was obtained from the rhizosphere of Phragm ites australis. A granular activated carbon (GAC) biofilm reactor was estab lished using this consortium, and the degradation of 4-CP was investigated under continuous flow operation using a feed of 20-50 mg l(-1) with a hydra ulic residence time of 17 min over a 6-month period. Chloride liberation oc curred throughout the operation, and the reactor had 4-CP removal efficienc ies of 69-100%. Periods of lower performance were attributed to clogging of the column with biomass and the formation of channels. Subsequently, the i mmobilized biofilm was subjected to a starvation period of 5 months, after which its degradative capacity was still maintained. The microbial consorti um was characterized during the continuous flow experiment and dynamic popu lation changes were observed throughout. One isolate recovered from the bio film was shown to be capable of degrading 4-CP as a sole carbon and energy source.