Anaerobic biodegradation of pentachlorophenol in a liquor obtained after extraction of contaminated chips and wood powder.

Recovery of 97.5% of the pentachlorophenol (PCP) in contaminated wood powder was obtained after extraction with 0.1% KOH solution at 60 degrees C for 75 min. Extraction with NaOH and Na2CO3 was less effective than KOH. The neutralized extract was treated using a methanogenic consortium in an upflow anaerobic fixed-film reactor. The reactor was operated at 29 degrees C for over 600 d. The best performance of the reactor was observed when the PCP liquor was supplemented with glucose and formate. Complete dechlorination of PCP and phenol removal was obtained for a PCP loading rate of 13.3-18.0 mg l(-1) of reactor volume d(-1) with recirculation of the effluent and a hydraulic retention time (HRT) of 0.5-0.6 d.