Cooperative denitrification in biocathodes under low carbon to nitrogen ratio conditions coupled with simultaneous degradation of ibuprofen in photoanodes

Abstract

A two-chamber microbial photoelectrochemical cell (MPEC) with a denitrification biocathode and an α-Fe₂O₃/P3HT photoanode was established aimed to enhance nitrate removal from wastewater of low carbon sources and achieve simultaneous ibuprofen degradation. The results demonstrated that the average removal of NO₃^--N in the biocathode reached 96.56 ± 0.72% when the COD/NO₃^--N was 0.75, and the relative contributions of heterotrophic and autotrophic denitrification were 21.47% and 78.53%, respectively. When there was no organic source in the influent, the maximum removal of NO₃^--N was less than 45%. High-throughput sequencing revealed that both heterotrophic bacteria, such as Bacillus, and autotrophic bacteria (e.g., Thermomonas and Hydrogenophaga) dominated in the cooperative denitrification biocathode. Moreover, the functional gene analysis showed that the abundance of genes related to denitrification was highest in the cooperative denitrification biocathode. In addition, the photocatalytic degradation efficiency of ibuprofen in the anode chamber attained 67.95% ± 0.97%.

Keywords: Cooperative denitrification biocathode; Ibuprofen; Low carbon to nitrogen ratio; Photocatalytic anode.