Biodegradation kinetic studies for the removal of p-cresol from wastewater using Gliomastix indicus MTCC 3869

Abstract

Biodegradation of p-cresol by a pure culture of new filamentous fungal strain Gliomastix indicus was studied. The fungus strain was acclimatized to the higher concentration of 700 mg/l of p-cresol in modified czapeck medium over a period of two months. The lag period was 24 h. The shake flask batch experiments were carried out at temperature of 28 °C and pH of 6 over a wide range of initial p-cresol concentration (10–700 mg/l) keeping initial biomass concentration constant at 18.72 mg/l. Experimentally it was observed that p-cresol was inhibitory type substrate and the inhibition effect of p-cresol became predominant above a concentration of 50 mg/l. The kinetics of cell growth and p-cresol degradation were investigated. Six kinetic models (Haldane, Andrews, Webb, Yano, Aiba, and Teissier) were fitted to the experimental growth kinetic data. Models by Haldane, Andrews, Webb and Yano (correlation coefficient R 2 > 0.99) were found to be most suitable models. In addition, the variation of observed yield coefficient Y X with specific growth rate μ g was investigated. The maintenance energy coefficient and true growth yield coefficient, were found to be 0.0227 h −1 and 1.0708 (mg/mg), respectively. The specific substrate utilization rate was represented in terms of specific biomass growth rate. The decay coefficient was found to be 0.0055 h −1. The effect of pH and nitrogen source of medium on biodegradation of p-cresol was investigated as well.