The regulating role of applied voltage on methanogenesis in an up-flow single-chamber microbial electrolysis assisted reactor

Applied voltage was introduced into the anaerobic system for improving the efficiency of sewage treatment and bioenergy production. For better energy efficient applications, it was necessary to have a good understanding of the effect of applied voltage, which is different from the conductive materials. In this study, the effects of applied voltage at different positions were investigated, considering the concentration gradients. Results showed that the maximum COD removal efficiency was 96.7% and the methane production rate was 0.434 ± 0.018 m³ CH₄/m³/day in the reactor with two pairs of electrodes. The effect of the applied voltage on the organic matter conversion and methane production were dominant in the lower electrode. The increased energy output could content the required electric energy, and additional energy could be generated by CHP. The contribution of electrochemical direct action was lesser, and the increase of applied voltage led to the enrichment of functional microbes in this system, especially the hydrogenotrophic methanogens dominated by Methanocorpusculum.