Kinetics of styrene biodegradation in synthetic wastewaters using an industrial activated sludge

Kinetics of styrene biodegradation in synthetic wastewaters, containing either styrene or styrene together with ethanol, by an industrial activated sludge obtained from the wastewater treatment unit of a petrochemical complex was studied. The kinetic data could be fitted using the Haldane kinetic model. This model was previously used to predict kinetic data for biodegradation of styrene by pure or mixed microbial cultures isolated from biofilters, but the values of the model parameters reported in these studies was substantially different from that obtained for the industrial activated sludge. The presence of ethanol did not affect the kinetics of styrene biodegradation by the industrial activated sludge; however, it increased the rates of styrene biodegradation due to the resulting higher microbial growth rates. Styrene concentration was found to affect the specific growth rate in a manner similar to its effect on the styrene degradation rate. No lag phase was observed in styrene biodegradation by industrial activated sludge for styrene concentrations up to 100mg/L. Lag phase was observed for municipal activated sludge even at 50mg/L styrene concentration but the rate of styrene biodegradation after the lag phase was similar to that achieved by the industrial activated sludge.