Enhanced power generation and desalination rate in a novel quadruple microbial desalination cell with a single desalination chamber

Microbial desalination cell (MDC) is considered as an eco-friendly technology for water purification in which organic contaminants in wastewater are used as energy source to drive the desalination process. MDCs with a single-desalination chamber (single-DC MDC) offers a simple desalination configuration without facing the challenges associated with electrodialysis stacked MDC (ED-SMDC), e.g., osmosis water loss and high internal resistance. However, single-DC MDCs suffer from low desalination rate, low power recovery, and high anolyte to saltwater volume ratio. To address these challenges, this present study provides insights into a polygonal MDC design by proposing a new quadruple microbial desalination cell (QMDC). The QMDC performance was investigated under three different connection configurations; i.e., individual (IQMDC), parallel (PQMDC), and series (SQMDC). Among these configurations, PQMDC showed the lowest internal resistance over the desalination cycle along with the highest power recovery of 17.7 mW, overall desalination rate of 48.12 mg/h, and desalination ratio of 98.9%. These findings revealed 127% and 88% increases in power generation and mass desalination rate in comparison with the values obtained in the conventional three-chamber MDC, respectively. Step by step evaluation of the QMDC performance in terms of continuous current generation, mass and concentration desalination rates, and power recovery revealed that the QMDC performance was most affected by the internal resistance as the main controlling factor. The results also showed that the performance of the developed polygonal (quadruple) MDC could compete with that of the ED-SMDCs through optimizing reactor configuration.