Enhanced treatment of petroleum refinery wastewater by short-term applied voltage in single chamber microbial fuel cell

•Supplementation of mild voltage to MFC in the initial phase helped for efficient electroactive biofilm.•Petroleum refinery wastewater (PRW) evidenced maximum influence at 500 mV of applied potential for 24 h.•Substrate degradation and power generation enhanced for at least 50%.•Long chain alkanes/diesel range organics were degraded up to 89% Electrochemically active anodic biofilm that has adapted under mild applied potentials in the range 100–500 mV was evaluated for its improved bioelectrogenesis and bioelectrochemical treatment of petroleum refinery wastewater (PRW) in a single chamber air cathode microbial fuel cell (MFC). MFC operation with 500 mV as supplemental voltage has exhibited a maximum power density of 132 mW/m2, which was three times higher than control MFC (45 mW/m2). Similarly, highest substrate removal efficiency (48%) was also obtained with the MFC of 500 mV, followed by 300 mV (37%), 100 mV (32%) and control (27%). Adaptation under applied potential conditions also exhibited enhanced degradation efficiency of diesel range organics (DROs)/straight chain-alkanes. The strategy efficiently reduced DROs with the maximum efficiency of 89% (500 mV), which is almost 50% higher than that of the control system (59%), demonstrating the effectiveness of using supplemented voltage in treating PRW.