Effect of nitrate concentration on power generation and nitrogen removal in microbial fuel cell

ABSTRACT Microbial fuel cell (MFC) technology with decarbonization and denitrification is considered to be advantageous in treating wastewater with a low carbon-to-nitrogen ratio. In this study, MFC was treated with different concentrations of nitrate-nitrogen. The MFC technology revealed significant treatment advantages when compared to both abiotic electrode treatment and microbial treatment only. The best treatment effect was recorded when the MFC's nitrate-nitrogen ( ) concentration was 414 mg/L. The running of the MFC system showed that it produced a stable output voltage of up to 0.17 V within 160 h. It showed a power density of up to 40.18 mW/m2, 1.58 times M1 (138 mg/L, 25.49 mW/m2), and 4.48 times non-biological electrode. The removal rate of was 97.48%, but the lack of anode electron supply resulted in the incomplete reduction of nitrate-nitrogen and accumulation of nitritenitrogen. Nitrate-nitrogen concentration in the study had no significant impact on microbial population diversity. However, the relative abundance of Proteobacteria increased from 47.3% to 65.4% when concentration increased from 138 to 414 mg/L. Burkholderiales, Hydrogenophilales, and Rhodocyclales were the main denitrifying bacteria. These results demonstrate promise in supporting the development of microbial cathode denitrification.