Power Generation by Halophilic Bacteria and Assessment of the Effect of Salinity on Performance of a Denitrifying Microbial Fuel Cell

Saline wastewater pollution is a critical issue that needs to be addressed. The present study focused on the development of a dual-chambered microbial fuel cell (MFC) treating saline wastewater at the anode. Halophilic exo-electrogenic bacteria enriched from seawater (Arabian Sea, Mumbai, India) were used in the anodic chamber of the MFC. Denitrification using denitrifying bacteria was employed in the cathodic chamber. The maximum power density was significantly increased from 96.77 mW/m(2) to 162.09 mW/m(2) with a rise in NaCl concentration from 20 to 40 g/L. Nitrate removal in the cathode chamber increased from 80 +/- 3% to 89 +/- 3.2% with increase in salt concentration from 20 g/L to 40 g/L and concomitantly COD removal in the anode chamber increased from 76 +/- 3.8% to 83 +/- 4%. Cyclic voltammetry (CV) analysis revealed higher electrochemical activity at 40 g/L salt concentration. Electrochemical impedance spectroscopy (EIS) analysis exhibited that charge transfer and solution resistances were lower when the salinity was increased. Microbial community analysis revealed the presence of Clostridium, Shewanella, and Bacillus as the most abundant genera in the anodic chamber. This study demonstrated the dual applicability of the system targeted for removal of organics from saline wastewater and nitrate removal from contaminated wastewater accompanied by power generation from the MFC.

Automated summary

This study developed a dual-chambered microbial fuel cell (MFC) for the treatment of saline wastewater. The use of halophilic exo-electrogenic bacteria in the anodic chamber and denitrifying bacteria in the cathodic chamber significantly improved the power generation and removal of organics and nitrate. Electrochemical analysis showed enhanced activity and lower resistance with increased salinity. Microbial community analysis identified Clostridium, Shewanella, and Bacillus as the predominant genera in the anodic chamber. Overall, this study demonstrated the dual applicability of the MFC system for organics and nitrate removal from saline and contaminated wastewater while generating power.