Biohydrogen facilitated denitrification at biocathode in bioelectrochemical system (BES)

Abstract

Reductive removal of nitrate in bioelectrochemical system (BES) at abiotic cathode, biocathode and biohydrogen facilitated biocathode were investigated. It was found that nitrate removal efficiency reached 95% and 59% at the biohydrogen facilitated biocathode and biocathode respectively, while which was only 13% at the abiotic cathode. Meanwhile, activity of nitrate reductase reached 0.701g-N/Lh for the biohydrogen facilitated group, which was about 9.3times of the biocathode group. Moreover, electrochemical performances as power density, ohmic resistance, and polarization resistance of the biohydrogen facilitated group reached 76.96mW/m3, 8.63ohm and 383ohm, respectively, which were better than two other groups. Finally, an obvious shift of bacterial community responsible for the enhanced nitrate reduction between the two biocathode groups was observed. Therefore, nitrate reduction in BES could be enhanced at the biocathode than that of the abiotic cathode, and then be further boosted with the combination of biohydrogen.