Membrane cleaning and performance insight of osmotic microbial fuel cell

Abstract

Osmotic microbial fuel cell (OsMFC) integrating forward osmosis into microbial fuel cell (MFC) favors the merits of organic removal, bioenergy generation, and high-quality water extraction from wastewater. This study demonstrated an 18.7% power density enhancement over a conventional MFC due to the water-flux-facilitated proton advection and net positive charge (NPC)-flux-promoted countercurrent proton exchange. Among the three examined membrane cleaning methods, chemical cleaning using 0.2% NaClO was found to be especially effective in removing organic foulants composed of proteins and polysaccharides, resulting in a water flux recovery of up to 91.6% with minimal impact on average maximum power density and internal resistance. The effects of operating parameters including anode HRT and draw solution concentration were studied. Shortening HRT from 6.0 to 3.0 h increased power density by 78.0% due to a high organic loading rate and a slightly reduced polarization concentration. Increasing draw solution concentration from 0.2 to 1.0 M NaCl enhanced power density by approximately 2.7-fold due to enhanced proton advection. Water-flux-facilitated proton advection played a more important role in determining the electricity generation performance of OsMFC than the NPC-flux-promoted countercurrent proton exchange under varied operating conditions.