The potential of electrotrophic denitrification coupled with sulfur recycle in MFC and its responses to COD/SO42− ratios

Electrotrophic denitrification is a promising novel nitrogen removal technique. In this study, the performance and the mechanism of electrotrophic denitrification coupled with sulfate-sulfide cycle were investigated under different anodic influent COD/SO42- ratios. The results showed that electrotrophic denitrification contributed to more than 22% total nitrogen removal in cathode chamber. Higher COD/SO42- ratios would deteriorate the sulfate reduction but enhance methane production. Further mass balance indicated that the electron flow utilized by methanogenic archaea (MA) increased while that utilized by sulfate-reducing bacteria (SRB) decreased as the COD/SO42- ratio increased from 0.44 to 1.11. However, higher COD/SO42- ratios would produce more electrons to strengthen electrotrophic denitrification. Microbial community analysis showed that the biocathode was predominantly covered by Thiobacillus that encoded with narG…