Two-stage microbial fuel cell (MFC) and membrane bioreactor (MBR) system for enhancing wastewater treatment and resource recovery based on MFC as a biosensor.

Lack of process control between the two stages of a combined microbial fuel cell-membrane bioreactor (MFC-MBR) system limits its application in wastewater treatment due to membrane fouling and high energy consumption. In this study, a two-stage MFC-MBR integrated system was established to investigate the impact of incorporating process control on petroleum refinery wastewater treatment. The results showed that chemical oxygen demand (COD) removal exhibits a linear relationship with the MFC voltage output (R = 0.9821); therefore, the MFC was used as a biosensor to control the combined system. The removal efficiencies of COD, ammonium nitrogen (NH-N), and total nitrogen (TN) were 96.3%, 92.4%, and 86.6%, respectively, in the MFC-MBR biosensor, whereas those in the control system were 74.7%, 71.2%, and 64.7% respectively. Furthermore，using the biosensor control system yielded a 50% reduction in the transmembrane pressure (1.01 kPa day) and decreased membrane fouling in wastewater treatment. The maximum energy recovery of the biosensor system (0.00258 kWh m) was five times higher than that of the control system, as determined by calculating the mass balance of the system. Thus, this study indicates that using the MFC as a biosensor for process control in an MFC-MBR system can improve overall system performance.