Competitive microbial reduction of perchlorate and nitrate with a cathode directly serving as the electron donor

Simultaneous phenol removal, nitrification and denitrification using microbial fuel cell technology

Here we show that concomitant removal of phenol and nitrogen can be accomplished in a single dual-chamber microbial fuel cell (MFC) reactor, in which the two chambers are separated with an anion-exchange membrane. A series of experiments were performed with ammonium (230 NH4(+)-N mg L(-1)) and phenol (with concentrations varying from 0 to 1400 mg L(-1)) fed to the aerobic cathode chamber of the MFC. Experimental results demonstrated that no apparent inhibitory effect of phenol on the nitrifying reaction was noted even at the phenol concentration up to 600 mg L(-1). For all the experiments, simultaneous nitrification and denitrification was achieved in the MFC. In comparison to the traditional aerobic bioreactor (ABR) and the same MFC run under the open-circuit condition, the MFC reactor allowed less inhibition of nitrification to phenol exposure and higher rate of nitrogen removal. The data of bacterial analysis revealed that electrochemically active bacteria and denitrifiers in the anaerobic chamber play a significant role in electricity generation and anaerobic denitrification, respectively, while phenol-degrading bacteria, nitrifiers, and denitrifiers in the aerobic cathode chamber are responsible for phenol oxidation, aerobic nitrification and aerobic denitrification, respectively. These results imply that the MFC holds potential for simultaneous removal of phenolic compounds and nitrogen contained in some particular industrial wastewaters.