Start-up of a membrane bio-electrochemical reactor: technology for wastewater treatment and energy generation

Abstract

Membrane bio-electrochemical reactors (MBER) are the combination between microbial fuel cells (MFC) and membrane bioreactors (MBR). This technology presents a high potential for wastewater treatment and nutrients removal, especially nitrogen, while generating energy from the fuel cell by electron production and transfer by bacteria in biochemical reactions. The aim of this work was to evaluate energy generation and the removal of pollutant (organic matter and nitrogen compounds) during the start-up of a pilot-scale MBER. The MBER system was assembled with the cathode in an anoxic chamber, the anode in an anaerobic one, and ultrafiltration membranes in the aerobic compartment. Results show biochemical oxygen demand (BOD5) and chemical oxygen demand (COD) removals of 97 ± 3% and 97 ± 1%, respectively. Beyond that, total nitrogen removal was 80 ± 17% and the system showed high capacity for nitrification, with ammoniacal nitrogen (N-NH3) removal of 88 ± 19%. Even during start-up, the voltage generation achieved values similar to the ones of stable MBERs, with maximum voltage obtained of 482 mV. In summary, the results indicate that, even during start-up, the permeate had a similar quality to the permeate produced by membrane bioreactors, while generating energy between the electrodes.