Process engineering for stable power recovery from dairy wastewater using microbial fuel cell

Abstract Microbial fuel cells (MFCs) are one of the sustainable technologies that can effectively treat wastewater with concomitant generation of electricity. The present study investigated the treatment of real dairy wastewater (RDW) using Shewanella algae (MTCC-10608) within a single chamber microbial fuel cell (SCMFC). The study was conducted in both batch and fed-batch modes with initial chemical oxygen demand (COD) of 4000 mg/L and 2000 mg/L, respectively, in 0.2 L working volume of RDW for 15 days. However, the fed-batch strategy involved subsequent feeding of dairy wastewater with 6000 mg/L and 8000 mg/L COD on the 5th and 10th day, respectively. This two-step feeding strategy resulted in a maximum open-circuit voltage of 666 mV at 286 h of incubation with a COD removal efficiency of 92.21% and a columbic efficiency of 27.45%. The kinetic studies predicted the saturation constant of 55.83 mg COD/L and current density of 143.3 mA/m2, which are similar to the findings from the experiments and polarization curve obtained. The maximum current density and power density from experiments were found to be 141 mA/m2 and 50 mW/m2 respectively. Thus, this study successfully indicates the utilization of dairy wastewater as a potential substrate for the sustainable power generation using Shewanella algae as a biocatalyst in the microbial fuel cell.