Simultaneous nitrification, denitrification and electricity recovery of Halomonas strains in single chamber microbial fuel cells for seawater sewage treatment

Abstract

Simultaneous nitrification and denitrification (SND) by microbial fuel cell (MFC) holds great promise in the nitrogen removal from seawater sewage due to the harvest of electricity and low organic carbon requirement. However, this remains very difficult owing to the inhibition of microbial growth and metabolism by the high salinity. In this work, a halophilic bacterium Halomonas sp. B01 with both exoelectrogenic and SND capability in hypersaline environment was reported. Halomonas sp. B01 was screened from several Halomonas species considering their growth and electricity production abilities. Halomonas sp. B01 generated a high power density of 24.2 mW/m2 (0.61 W/m3) and efficient N removal rate of 93.8% in single chamber MFCs on seawater substrate. The nitrogen removal pathway of Halomonas sp. B01 was demonstrated to include (1) nitrification process coupled with electron-donating to the anode, and (2) denitrification process coupled with electron-accepting from the cathode. The present work represents a successful attempt to accomplish simultaneous SND and electricity production in MFCs by a single halophilic strain, which provides a theoretical and method support for the convenient treatment of seawater sewage.