Enhanced power generation, organics removal and water desalination in a microbial desalination cell (MDC) with flow electrodes

• Published in: The Science of the total environment Vol. 858; no. Pt 2; p. 159914
• Main Authors: Yang, Zhigang, Li, Yunfei, Zhan, Ziyi, Song, Yang, Zhang, Lijie, Jin, Yan, Xu, Linxu, Wang, Jin, Shen, Xue, Liu, Liming, Chen, Feiyong
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2023
• Subjects: activated carbon; anodes; bacterial communities; carbon nanotubes; chemical oxygen demand; desalination; electric potential difference; electricity; electrochemistry; Electron harvest; environment; Flow electrode; Hydrogenophaga; microbial activity; Microbial desalination cell; power generation; Pseudomonas; slurries; Wastewater treatment; Water desalination; Flow electrode; Microbial desalination cell; Water desalination; Wastewater treatment; Electron harvest
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2022.159914

This study introduced a flow electrode microbial desalination cell (FE-MDC), which used activated carbon (AC) particles and carbon nanotubes (CNTs) as the electrode to promote electron harvesting. The recovered electricity energy (0.371 KWh/m3) and columbic efficiency (66.7 %) of the FE-MDC were over 2 times higher than those of the conventional MDC without the flow electrode. Consequently, the salt and COD removal efficiencies were enhanced to 77.8 % and 91.2 %, respectively. Electrochemical analysis implied that the charge transfer resistance of the system was reduced by the flow electrode. Electron accumulation and charging-discharging experiments proved that the flow electrode could accumulate electrons and transfer the electrons to the fixed anode. Bacterial community analysis indicated that the bacterial activity was improved by the flow electrode. The content of the exoelectrogen Pseudomonas increased from 5.0 % to 14.7 %, and Hydrogenophaga improved from 1.4 % to 5.9 %. Finally, a continuous operation mode of the FE-MDC was established, and the flow electrode slurry was returned to the anodic chamber for recirculated utilization. The voltage output, COD removal, and salt removal during the operation mode reached 610 mV, 78.8 %, and 76.1 %, respectively. This study proved that the flow electrode is a promising way to promote the practical application of MDC technology. [Display omitted] •FE-MDC performance is enhanced as harvested electrons increased more than 2 times.•Electrode electrochemical activity of the anode is improved using flow electrode.•Electrons accumulated at the flow electrode then transferred to the fixed anode•Bacterial richness decreased while live cells and Pseudomonas contents increased.