An indigenous mixed microbial culture isolated from an effluent treatment section of a coke oven plant has been studied for its m-cresol biodegradation capacity under aerobic batch reactor operation. The culture, after acclimatization could biodegrade up to 700 mg/L of m-cresol. The m-cresol concentration in the present study was at 50 mg/L and then ranged from 100 to 700 mg/L with step up concentration of 100 mg/L. Both biodegradation kinetics and microorganism growth kinetics were studied and kinetic parameters were estimated. The result showed that m-cresol was an inhibitory-type substrate and the inhibition effect became predominant after 200 mg/L of initial m-cresol. The specific growth rate of microorganisms increased up to 200 mg/L of m-cresol as sole carbon source, and then started decreasing. The kinetic data obtained in this study have been fitted to different substrate inhibition models (Haldane, Han-Levenspiel, Edward, Luong, Aiba, Teissier, Yano-Koga). Among all models, Han-Levenspiel and Luong were best fitted for this study (root mean square error = 0.001349). In addition, the variation of observed yield coefficient Yx/s with initial m-cresol concentration was investigated. The values of kinetic constants estimated by the models proved that the mixed culture used in the study had good potential for m-cresol degradation.

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