The Optimization, Kinetics Model, and Lab-Scale Assessments of Phenol Biodegradation Using Batch and Continuous Culture Systems

Abstract

Phenol was considered a severe hazard to all ecosystems even at low concentrations. The bioremediation process is an eco-friendly process for complete phenol degradation and bioelectricity generation. In the present study, a consortium of native isolates was used for phenol biodegradation and bioenergy generation using nano-graphite electrodes. The optimization of nutritional and environmental parameters using batch culture revealed that the optimum conditions for maximum phenol degradation and energy generation were inoculum concentration, 1%; incubation period, 48 h; phenol, 6 ppm; MgSO4, 70 mg/L; K2HPO4, 175 mg/L; and CaCl2, 1 mg/L. Phenol biodegradation reached 93.34% with a power density of 109.419 mW/cm3. A lab-scale bioreactor was used as a continuous culture with aeration rate, agitation speed, and dissolved oxygen of 0.5 v/v/m, 750 rpm, and 30%, respectively. On using the continuous culture, phenol biodegradation and bioenergy production reached 97.8% and 0.382 W/cm3, respectively. A kinetics study using Haldane’s kinetics model reported the best fit to achieve a significant correlation coefficient (R2) value (0.9865) reaching maximum specific growth rate with initial phenol concentration of approximately 9 mg L−1 where the specific growth rates (μ, h−1) varied with different initial phenol concentrations. In conclusion, the native isolated consortium could be considered as an economical and sustainable approach to phenol biodegradation in industrial wastewater as well as bioelectricity generation.