Effect of dissolved oxygen concentration on nitrogen removal and electricity generation in self pH-buffer microbial fuel cell

A double-chamber self pH-buffer microbial fuel cell (MFC) was used to investigate the effect of dissolved oxygen (DO) concentration on cathodic nitrification coupled with anodic denitrification MFC. It was found that nitrogen and COD removal, electricity generation were positively correlated with DO concentration in the cathode chamber. When total inorganic nitrogen of influent was 202.51 +/- 7.82 mg/L at DO 6.8 mg/L, the maximum voltage output was 282 mV and the maximum power density was 149.76 mW/m(2). After 82 h operation, the highest removal rate of total inorganic nitrogen was 91.71 +/- 0.38%. Electrochemical impedance spectroscopy (EIS) test showed that the internal resistance of the reactor with different DO concentration was related to the diffusion internal resistance. The data of bacterial analysis in the cathode chamber revealed that there were not only ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB), but also a large number of exoelectrogens. Compared with the traditional biological denitrification and related MFC denitrification research, this method does not need pH-buffer solution and external circulation device through the anion exchange membrane (AEM). It can generate electricity and remove nitrogen simultaneously, and the oxygen utilization rate in the cathode can also be enhanced. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.