Bioelectricity Generation from Acidogenic Palm Oil Mill Effluents using Microbial Fuel Cells

Microbial fuel cell offers a promising approach to improve wastewater quality and generate bioenergy from dark fermented effluents. In this study, the use of dark-fermented palm oil mill effluent as an electron donor for bioelectricity generation was investigated using a double-chambered microbial fuel cell (MFC). The MFCs were operated at room temperature (29 {+/-} 2{degrees}C), anode electrolytes adjusted to pH 7, and a chemical catholyte as the oxidizing agent. The maximum power {+/-} 8.07 mW/m2 and 155.16 {+/-} 12.88 mA/m2, respectively, were generated from the MFCs inoculated with sludge, which was 5.9 times higher than control without inoculum. Microbial community analysis revealed the enrichment of fermentative and electrogenic representative taxa from the phyla Bacillota, Bacteroidota and Pseudomonadota on the anode electrodes. Optimizations of the running conditions were carried out, suggesting the optimum parameters of 0.5 k{Omega} external resistance, anolyte initial pH 9, and 75% DFPOME substrate concentration. Operation under the optimized conditions increased current production, wastewater treatment, and Coulombic efficiency compared to the non-optimized conditions. Multiple configurations were also evaluated, showing higher cumulative voltage, power, and current densities with the stacked MFC connections, compared to single MFC units. Parallel circuit connection produced higher power and current density than serial connection. This study demonstrated the feasibility of MFC as a promising downstream treatment for biohydrogen production processes, towards higher treatment efficiency and resource recovery.