Investigating the response of electrogenic metabolism to salinity in saline wastewater treatment for optimal energy output via microbial fuel cells

• Published in: The Science of the total environment 2021-08, Vol.783, p.147092-147092, Article 147092
• Main Authors: Xiao, Yihang, Lin, Sen, Hao, Tianwei
• Format: Article
• Language: English
• Subjects: Electron transfer; Energy harvest; Microbial fuel cells; Saline wastewater; Sulfidogenesis
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.147092

In the current study, MFCs treating saline wastewater with the different conductivities of 5.0 ± 0.2, 7.7 ± 0.6, 10.5 ± 0.9, 13.0 ± 1.0, 15.3 ± 1.0, and 16.0 ± 0.1 mS/cm were investigated. Increasing salinity drives a considerable shift of microbial communities, and it also affects metabolic pathways in MFCs. Overwhelming acetate oxidizing electron transfer with moderate conductivities between 7.7 and 13.0 mS/cm led to high energy outputs. Power generation at the low conductivities of less than 7.7 mS/cm was restricted by the competition between fermentative bacteria (e.g., Lactobacillus) and exoelectrogens (e.g., Pseudomonas and Shewanella) for substrate utilization. Increasing salinity beyond 13 mS/cm suppressed the fermentation of glucose to butyrate. It also induced sulfidogenesis; sulfide oxidizing bacteria Desulfovibrio (5.2%), Desulfuromonas (3.7%) and exoelectrogen Pseudomonas (1.1%) formed a sulfur-driven current production, thereby resulting in low energy outputs. The present study revealed the effects of ionic conductivity on electrical energy production and provided insights into the dynamics of the MFCs substrate utilization. [Display omitted] •MFCs treating saline wastewater with different conductivities were investigated.•Low power generation under 8 mS/cm was restricted by the thriving fermentation.•Acetate oxidizing electron transfer led to efficient power generation at 8–13 mS/cm.•More energy metabolism enzymes at 11 mS/cm attributed to higher energy transfer.