Microbial electrolysis cells (MECs) have rapidly developed into a promising technology to treat sulfaterich wastewater that lacks electron donors. However, little is known regarding the effect of different carbon sources on the microbial community structure bioelectrochemical systems. This study sought to investigate the effect of different carbon sources (NaHCO 3 , ethanol, and acetate were employed as sole carbon source respectively) on the performance of sulfate-reducing biocathodes. The sulfate reduction e ciency enhanced by the bioelectrochemical systems was 8.09%−11.57% higher than that of opencircuit reference experiments. Furthermore, the optimum carbon source was ethanol with a maximum sulfate reduction rate of 170 mg L −1 d −1 in the bioelectrochemical systems. The different carbon sources induced signi cant differences in sulfate reduction e ciency as demonstrated by the application of a micro-electrical eld. The dominant sulfate-reducing bacteria that use NaHCO 3 and acetate as carbon sources were Desulfobacter and Desulfobulbus, whereas those that use ethanol as carbon source were Desulfomicrobium and Desulfovibrio. Our results suggest that ethanol is a more suitable carbon source for sulfate reduction in bioelectrochemical systems.

Microbial electrolysis cells (MECs) have rapidly developed into a promising technology to treat sulfate-rich wastewater that lacks electron donors. However, little is known regarding the effect of different carbon sources on the microbial community structure bioelectrochemical systems. This study sought to investigate the effect of different carbon sources (NaHCO3, ethanol, and acetate were employed as sole carbon source respectively) on the performance of sulfate-reducing biocathodes. The sulfate reduction efficiency enhanced by the bioelectrochemical systems was 8.09%−11.57% higher than that of open-circuit reference experiments. Furthermore, the optimum carbon source was ethanol with a maximum sulfate reduction rate of 170 mg L−1 d−1 in the bioelectrochemical systems. The different carbon sources induced significant differences in sulfate reduction efficiency as demonstrated by the application of a micro-electrical field. The dominant sulfate-reducing bacteria that use NaHCO3 and acetate as carbon sources were Desulfobacter and Desulfobulbus, whereas those that use ethanol as carbon source were Desulfomicrobium and Desulfovibrio. Our results suggest that ethanol is a more suitable carbon source for sulfate reduction in bioelectrochemical systems.