Abstract
Sludge from wastewater treatment plant of petrochemical industry was acclimatized to 2-chlorophenol under anaerobic conditions. The sludge could degrade 100 mg·l-1 of 2-chlorophenol to methane in a day via phenol and benzoate. Addition of unacclimatized activated sludge at appropriate intervals was effective to stabilize the degradation activity.
Optimum temperature for degradation of 2-chlorophenol was 40°C and the optimum pH was 7.5. Of three monochlorophenols, only 2-chlorophenol was degraded. As for dichlorophenols, only the Cl group ortho to phenolic OH was reductively dechlorinated and 3- or 4- chlorophenol was formed from 2,3- or 2,4-dichlorophenol without further degradation. 2,6-Dichlorophenol was degraded to methane completely. Among the trichlorophenols, 2,3,6- and 2,4,6-trichlorophenols were dechlorinated to produce 3- and 4-chlorophenols, respectively.
We also discuss the mechanism of reductive dechlorination by the sludge.
