Biodegradation of Phenol from Wastewater by Microorganism Immobilized in Bentonite and Carboxymethyl Cellulose Gel

Abstract

This study presents a microbial process for phenol degradation in coking wastewater. The optimum immobilized condition of the strain for degrading phenol was determined through orthogonal experiment. The free and immobilized microorganisms were examined for their capabilities on degrading phenol. Results indicated that the optimum immobilized conditions were 20% microorganism suspension, 5% bentonite, 3% sodium carboxymethyl cellulose content, and 1 h of crosslinking time. The biodegradation rate was optimized at 35°C and 0.23 gmL−1 of immobilized microorganism bead. The degrading rate for the immobilized microorganism bead was up to 95.96% at an initial phenol concentration of 100 mgL−1; however, the immobilized microorganism considerably took more time (288 h) to reach 94.6% removal efficiency at a much higher concentration of 1000 mgL−1. The batch experiment demonstrated that 94.50% of phenol was removed using the beads with the immobilized microorganism at an initial concentration of 500 mgL−1. By contrast, only 24.60% and 33.88% of phenol were degraded using the gel beads without and with free microorganisms, respectively. The immobilized microorganism beads can used reused for up to nine cycles at the same initial phenol concentration (50 mgL−1) and can be stored up to 40 d without loss of its degradation capacity.