Influence of applied voltage on the performance of bioelectrochemical anaerobic digestion of sewage sludge and planktonic microbial communities at ambient temperature.

•Applied voltage affects the activities of EAB & PAB in bioelectrochemical digester.•At 0.5V, higher activity of EAB improves the methane content and methane yield.•Higher activity of PAB improves the methane production and energy efficiency at 0.3V.•The proper applied voltage for bioelectrochemical methane production is 0.3–0.5V.