Effects of alternative electron donors, acceptors and inhibitors on pentachlorophenol dechlorination in soil

The potential dechlorination of pentachlorophenol (PCP) in soil by a DCP-adapted consortium was investigated Results show that PCP dechlorination was enhanced under sulfate reduction and methanogenic conditions, but inhibited under denitrifying conditions within a 20-day incubation period. Under those same three conditions we also found that PCP dechlorination was enhanced by the addition of lactate, pyruvate, and acetate, but delayed by the addition of manganese oxide and inhibited by the addition of ferric chloride. In addition, our results failed to show any relationship between PCP dechlorination and oxidation-reduction potential (ORP) or changes in pH values. Treatment with lactate caused the greatest increase in methane production, the highest rates of sulfate or nitrate consumption; adding manganese oxide led to the second greatest increase, and the addition of ferric chloride the least. The addition of methylphenols and nitrophenols were found to inhibit PCP dechlorination. Methanogen may have constituted the major dechlorination population in our experimental consortium.