Mathematical modeling of the dynamic behavior of an integrated photo-bioelectrochemical system for simultaneous wastewater treatment and bioenergy recovery

An integrated photo-bioelectrochemical (IPB) system is innovative through integrating microbial fuel cells (MFCs) with algal bioreactors for simultaneous organics degradation, nutrient removal, and bioenergy production. A mathematical model has been developed for simulating and understanding the performance of the IPB system. The model inputs include influent COD (chemical oxygen demand), NH4+-N, total phosphorus, external resistance and flow rate, while the outputs include the biomass growth, COD degradation, nutrient removal, and electricity generation. The determination of unknown model parameters was assisted with sensitivity analysis. Satisfactory model fitting and validation was achieved, with low root-mean-square error of 5.6% and 0.2%, respectively, for biomass concentration and current generation under varied COD input. The simulated results suggested that the organic input and flow rate had more significant impacts on the growth of algal biomass than other input factors, while COD, flow rate and external resistance were of importance for current generation. The optimal condition for improving this particular IPB system was predicted to have a COD concentration above 150 mg L−1 and the flow rate at 0.1 mL min−1. This IPB model is the first attempt of the kind for the optimization of an integrated bioprocess of electrochemical reactions and algal growth.