title: Pentachlorophenol dechlorination by an acidogenic sludge.
abstract: This study reports the feasibility of removing pentachlorophenol (PCP) by an acidogenic process in batch reactors. When the acidogenic sludge was first acclimated with 2,4,6-trichlorophenol (2,4,6-TCP) and developed 2,4,6-TCP dechlorinating activity, PCP could be ortho-dechlorinated to 3,4,5,-trichlorophenol (3,4,5-TCP) via 2,3,4,5-tetrachlorophenol as the intermediary. However, due to PCP's higher hydrophobicity and its higher expected Gibbs free energy yield, it was adsorbed to the sludge and dechlorinated preferentially to 2,4,6-TCP. This resulted in the inhibition of 2,4,6-TCP dechlorination. PCP removal under acidogenic condition was attributed to both reductive dechlorination and adsorption. At low PCP loads of 0.48micromoles/gMLVSS.d, dechlorination was the dominant removal mechanism (69% of total removal), while at the higher PCP load of 9.3micromoles/gMLVSS.d, adsorption was the main mechanism (82% of total removal). Attempts to induce meta or para position dechlorination of PCP failed when using meta position chlorophenols such as 2,3,6-TCP, 3,4,5-TCP and 3,5-DCP as the initial substrates. Overall, acidogenic biotreatment was an effective process in reducing PCP loads prior to downstream biological treatment.
authors.affiliation: Division of Environmental Science & Engineering, National University of Singapore, Singapore 117576. g0304861@nus.edu.sg
authors.forename: Cheok Hong
authors.initials: CH
authors.lastname: Mun
authors.forename: Jianzhong
authors.initials: J
authors.lastname: He
authors.forename: Wun Jern
authors.initials: WJ
authors.lastname: Ng
mesh_terms: D000143:Acids; D000327:Adsorption; D002713:Chlorine / Q000737:chemistry*; D002733:Chlorophenols / Q000737:chemistry; D004785:Environmental Pollutants / Q000737:chemistry; D010416:Pentachlorophenol / Q000737:chemistry*; D010575:Pesticides / Q000737:chemistry; D012722:Sewage; D014867:Water; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000295:instrumentation / Q000379:methods
chemical_list: D000143:Acids; D002733:Chlorophenols; D004785:Environmental Pollutants; D010575:Pesticides; D012722:Sewage; D014874:Water Pollutants, Chemical; D014867:Water; C534098:3,4,5-trichlorophenol; D002713:Chlorine; D010416:Pentachlorophenol; C024564:2,4,6-trichlorophenol