Relevance of the Luong model to describe the biodegradation of phenol by mixed culture in a batch reactor

Abstract

The kinetics of phenol biodegradation by mixed culture in a batch reactor was investigated over a wide range of initial phenol concentrations (40-350 mg L -1). The temperature (30°C), the stirring velocity (200 rpm), mineral salt supplementation, namely NaH 2PO 4 (3 g L -1), KH 2PO 4 (3 g L -1), MgSO 4 (0.1 g L -1), (NH 4) 2SO 4 (1 g L -1), as well as the initial pH (8) were kept constant. All experiments were carried out at a given initial bacterial concentration of 0.08 g L -1 (based on the optical density determination, 0.079). Irrespective of the culture conditions, total phenol degradation was recorded for a culture time ranging from 15.6 to 49.0 h. In addition, the optimal value of the maximum specific growth rate was observed for 125 mg L -1 of phenol. These results show the relevance of the specific microbial consortium used. The Luong equation accurately matched growth kinetics and enabled the relation between the maximum specific growth rates (μm) and the initial phenol concentration (S o) to be described. It could also be used to deduce the substrate saturation coefficient (K s) and the maximum substrate concentration (S m) above which growth ceases. The kinetic constants of the Luong equation for phenol were μ m = 1:04 h -1; K s = 153:2mg L -1; S m = 540 mg L -1 and n = 0:9, respectively. © Springer-Verlag and the University of Milan 2011.