title: Biodegradation of 4-chlorophenol by acclimated and unacclimated activated sludge--evaluation of biokinetic coefficients.
abstract: Unacclimated and acclimated activated sludges were examined for their ability to degrade 4-CP (4-chlorophenol) in the presence and absence of a readily growing substrate using aerobic batch reactors. The effects of 4-CP on the micro (specific growth rate), COD removal efficiency, Y (yield coefficient), and q (specific substrate utilization rate) were investigated. It was observed that the toxicity of 4-CP on the culture decreased remarkably after acclimation. For example, the IC(50) value on the basis of micro was found to increase from 130 to 218 mg/L with the acclimation of the culture. Although an increase in 4-CP concentration up to 300 mg/L has no adverse effect on the COD removal efficiency of the acclimated culture, a considerable decrease was observed in the case of an unacclimated culture. Although 4-CP removal was not observed with an unacclimated culture, almost complete removal was achieved with the acclimated culture, up to 300 mg/L. The Haldane kinetic model adequately predicted the biodegradation of 4-CP and the kinetic constants obtained were q(m)=41.17 mg/(gMLVSSh), K(s)=1.104 mg/L, and K(i)=194.4 mg/L. The degradation of 4-CP led to formation of 5-chloro-2-hydroxymuconic semialdehyde, which was further metabolized, indicating complete degradation of 4-CP via a meta-cleavage pathway.
authors.affiliation: Department of Environmental Engineering, Middle East Technical University, Inonu Bulvari, 06531 Ankara, Turkey.
authors.forename: Erkan
authors.initials: E
authors.lastname: Sahinkaya
authors.forename: Filiz B
authors.initials: FB
authors.lastname: Dilek
mesh_terms: D000222:Adaptation, Physiological; D001420:Bacteria, Aerobic / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019149:Bioreactors; D002733:Chlorophenols / Q000378:metabolism* / Q000633:toxicity; D015169:Colony Count, Microbial; D007700:Kinetics; D008954:Models, Biological; D010461:Peptones; D012722:Sewage; D014865:Waste Disposal, Fluid
chemical_list: D002733:Chlorophenols; D010461:Peptones; D012722:Sewage; C029107:4-chlorophenol