Continuous Bioelectricity Generation from Phenol-Contaminated Water by Mediator-Less Microbial Fuel Cells: A Comparative Study between Air-Cathode and Bio-Cathode Systems

Due to metabolic activity of bacteria, microbial fuel cells (MFCs) can directly generate electricity by converting chemical energy of a biodegradable substrate to electrical energy. Simultaneous production of clean energy and wastewater treatment can be accomplished in these systems. In this study, phenol (100 - 1,000 ppm) as a toxic model of wastewater pollutant compounds was used as the sole source of carbon and energy for growth of bacteria and concomitant power generation in a dual-chamber MFC. Experiments were conducted in two lab-scale systems including an air-cathode and a bio-cathode MFC operating in continuous mode. Anode and bio-cathode chambers were inoculated with aerobic activated sludge from an industrial wastewater treatment plant. The highest output power was obtained at a phenol concentration of 700 ppm in both air-cathode (25 mW m(-2)) and bio-cathode (5 mW m(-2)) MFCs without using any co-substrate for the first time confirming the higher performance of the air-cathode electrode in oxygen reduction reaction. Phenol removal efficiency for an influent concentration of 700,ppm with an HRT of 125 min was 59.0% and 71.8% in bio-cathode and air-cathode MFCs, respectively. Cyclic voltammetry results confirmed involvement of both soluble and membrane-bound mediator components in electrochemical activity of anodic biofilm.