Novel microbial fuel cell integrating anoxic/oxic-membrane bioreactor design for simultaneous energy recovery and carbon–nitrogen removal from shale oil and gas wastewater

Shale oil and gas wastewater (SOGW), rich in pollutants, poses an environmental threat. A novel microbial fuel cell (MFC) resembling an anoxic/oxic-membrane bioreactor (A/O-MBR), called AOMM, was developed to treat SOGW and recover energy. AOMM required no expensive ion-exchange membrane and incorporated a custom suspended-rotating biocathode, reducing the reliance on high-cost and hard-to-scale components. Furthermore, AOMM achieved a maximum power density of 61.6 mW/m² and, under optimized operating conditions, removed 98.3% of chemical oxygen demand (COD), 99.6% of ammonium nitrogen (NH₄⁺-N), and 82.2% of total nitrogen (TN) from simulated SOGW. Microbial and gene analyses revealed enrichment of key bacteria and functional genes associated with electron transfer, carbon degradation, and nitrogen removal in both the anode and cathode. Moreover, AOMM demonstrated greater organic removal with a simpler process than an actual SOGW treatment project. This study provides an alternative with high application potential for efficient treatment and resource recovery of SOGW.