Revealing the performance of aerotolerant anodes for electroactive nitrification/denitrification and current production under coexistence of oxygen and nitrate conditions.

The coexistence of oxygen and/or nitrate at anode usually affects the biofilm activities of traditional anaerobic anode, thereby deteriorating wastewater treatment performance of microbial fuel cells (MFCs). Improving the aerotolerant responses of anode biofilms is a challenge for field application. In this study, we report that using the electroactive nitrifying/denitrifying inoculum and air-cathode expansion could fabricate the aerotolerant anode biofilms (AAB) under affordable nitrate stress (90 ± 5 mg/L). The highest average removal efficiencies were 99% for chemical oxygen demand (COD), NH 4 +-N and total nitrogen. The highest average current output of 0.69 mA and power density of 290 mW/m2 were obtained. The average current was confirmed to be reduced 10%–78% but the power density remained almost stable except the quart-air-cathodes MFC by increasing dissolved oxygen concentration with expansion of the air-cathode area. The higher oxygen concentration also contributed to oxidation of ammonium through electroactive autotrophic nitrification. The facultative anaerobic bacteria including Thauera , Microsillaceae , Shinella , Blastocatellaceae , Rhodobacter , Comamonadaceae , Caldilineaceae were enriched, which forms the AAB to remove nitrogen and produce current. Therefore, an easy-to-use method to fabricate AAB is evaluated to realize practical applications of MFCs in wastewater treatment. [Display omitted] • Aerotolerant anodes are fabricated in coexisting oxygen and affordable nitrate. • Currents are generated by aerotolerant anodes under high DO condition. • Aerotolerant anodes achieve efficient nitrogen removal and power recovery. • Increasing air-cathodes can enhance aerobic environment around the anodes. [ABSTRACT FROM AUTHOR]