Bioelectricity recovery through isolation and removal of nitrogen from wastewater by shortcut nitrification-denitrification in a coupled microbial fuel cell system

Abstract

Achieving both sustainable power recovery and efficient nitrogen removal in a single microbial fuel cell (MFC) reactor is a big challenge in the selection of external resistance and choosing favorable conditions. This study introduced a coupled MFC system (N-MFC and D-MFC) with a unique approach of isolating nitrogen input from wastewater and removing it via shortcut nitrification–denitrification, achieving treatment of wastewater along with improved energy recovery. The configuration of the N-MFC facilitated it to contribute significantly to the 98 % COD removal and to the 1.27 W m−3 energy recovered of the coupled MFC system. The results highlighted that operational circumstances affected MFC performance and offered insights into power generation, ammonium isolation, and shortcut nitrification in the N-MFC. The ratio of nitrite to nitrate was maximized at 2 under the dissolved oxygen (DO) condition of 0.6 mg/L, as opposed to 1.44 under the DO condition of 1.2 mg/L, during the shortcut nitrification process in the cathode chamber of N-MFC. The total nitrogen removal efficiency of the coupled MFC system was obtained at 50.2–71.2 %, proportionate to the COD influent and nitrite-to-nitrate ratio. The nitrogen removal of the coupled MFC system was significantly aided by autotrophic denitrification in the cathode chamber of D-MFC. The finding of this study emphasized the potential for optimizing the nitrogen removal in the D-MFC to increase the performance of N-MFC in power recovery by implementing the shortcut nitrification–denitrification process. This concept can be applied in practical for meeting the goals of SDG6 (Sustainable Development Goals) and clean energy production.