Abstract: To investigate the effects of different sulfur to nitrogen ratios (mass ratios of sulfur to nitrogen) on the nitrogen and sulfur removal and electrogenesis performance of microbial fuel cell (MFC), sodium sulfide ( $ Na_{2}S $) solution was used as anode simulated wastewater, potassium nitrate ( $ KNO_{3} $) solution was used as cathode simulated wastewater, and MFC activated sludge was inoculated in the anode and cathode chambers respectively. The results show that when the ratio of sulfur to nitrogen is 5:5, the nitrogen and sulfur removal and electrogenesis performance in the system is the best, the mass concentration of the nitrate outlet solution of the cathode chamber decreases from 100.00 mg/L to 8.68 mg/L, the conversion rate is 91.32%, the operating period is 90 h, and the average conversion rate is 24.35 mg/(L·d); the conversion rate of sulfide is 98.84%, the efficiency of nitrogen and sulfur removal is the highest. In addition, the current density and power density reach the maximum, which are 16 875 mA/m $ ^{3} $ and 1 560.56 mW/m $ ^{3} $, respectively. The 16S rRNA sequencing shows that Chlorobaculum, Desulfobacterium and Longilinea are the dominant bacteria related to sulfides degradation by MFC, and Acidovorax, Thermomonas and Nitrospira are dominant denitrifying bacteria. Sulfur to nitrogen ratio affects the abundance of dominant bacteria.
Keywords: sulfur to nitrogen ratio; microbial fuel cell (MFC); desulphurization and denitrification; electrogenesis; microbial flora