Improving electricity generation and substrate removal of a MFC–SBR system through optimization of COD loading distribution

Abstract

Incorporation of microbial fuel cell (MFC) into existing wastewater treatment systems is an important direction to bring MFCs into practical energy-efficient wastewater treatment application. Here, we report an integrated MFC–SBR (sequencing batch reactor) process with enhanced electricity generation by optimizing the chemical oxygen demand (COD) loading distribution between the MFC and SBR modules. The results show that the performances of individual modules in this system were linked through the “food chain”, and the overall system performance was governed by COD loading distribution. When excess COD was shunted to the SBR, the electricity generation decreased resulting from overgrowth of heterotrophs over cathode-respiration bacteria. Appropriately prolonging the hydraulic retention time (HRT) improved the system performance. With the HRT increased from 10 to 40min, the COD removal rate in the MFC increased by 52.4%, and the maximum power density increased from 3.9 to 4.5W/m3.