New insights into microbial fuel cells for saline wastewater treatment: Bioelectrogenesis evaluation, microbial interactions and salinity resource reuse

This first-attempted study displayed the multi-skilling performance of microbial fuel cells (MFCs) for treating saline wastewater in terms of soluble organics biodegradation, bioelectricity conversion, redox-mediators obtainment and salinity reuse. Results indicated that a bioelectricity conversion efficiency of ca. 0.865-0.960 kWh/kg CODMn with over 90% organics removal in 10.0-20.0 g NaCl/L conditions could be realized. Meanwhile, the redox mediators-like substances could be enriched from saline wastewater via MFCs treatment, which exhibited relatively high redox properties as electron shuttles. Moreover, the dominant members of Bacteroides, Azospirillum, Dyella, Sphingomonas, Ignavibacteriales and Clostridium cooperated together for completing bioelectrogenesis effectively with high capabilities of salinity tolerance. Higher salinity (ca. 30.0-40.0 g NaCl/L) impaired key hydrolase activities, reduce microbial metabolic functions and weaken anodic microbial diversity, which negatively reduce MFCs' running properties. Finally, the harvested salinity from saline wastewater through MFCs could be used effectively as a promising way of achieving waste sludge solubilization. This study could help to re-shape the thinking about future saline wastewater and excess sludge treatment/management toward resource recovery and cost minimization.