Treatment of dilute phenol/PCP wastewaters using the upflow anaerobic sludge blanket (USAB) reactor

UASB reactors started up well using phenol as the sole carbon source, and by day 46, COD removal efficiency was 100%. Pentachlorophenol (PCP) was then introduced at a concentration of 1 mg/l. Sequential appearance of tri-, di- and ultimately mono-chlorophenols was observed in the reactor effluent. After 70 days of operation, only 3-chlorophenol was detected in the reactor effluent. Increasing PCP concentrations led to transient appearance of PCP and other polysubstituted constituents in the reactor effluent; however, no toxic effects were observed over the range of PCP concentrations examined. Using phenol as an additional carbon source, the upflow anaerobic sludge blanket reactor proved capable of reducing highly chlorinated phenolic compounds into lightly chlorinated phenolics more amenable to subsequent aerobic degradation.