Synchronised treatment of groundwater & wastewater along with bioelectricity generation using a novel hexagonal microbial desalination cell

Microbial desalination cell (MDC) is a versatile bioelectrochemical system, which can simultaneously desalinate water and recover energy, while treating wastewater. The MDC technology, originally developed for desalting saline/brackish waters (10–35 g/L salt content), is explored for its possibilities in treating groundwater (GW), typically low in salinity. However, treating low saline water using conventional rectangular MDC (Conv MDC) configuration suffers from the limitations of poor power generation, reduced concentration gradient induced ion migration and consequent slower desalination rate. A novel hexagonal shaped MDC architecture (Hex MDC) with a single desalination chamber encircled by three pairs of anode and cathode chambers was proposed in this study to treat GW. This architecture offers an inherently lower inter electrode distance (D IE ), enhancing overall electro kinetics of MDC. Hex MDC was evaluated under: (i) two reactor connection configurations - adjacent (Hex adj ) and opposite (Hex opp ) connections; (ii) three electrical connection configurations – individual (Hex adj I), parallel (Hex adj - P), and series (Hex adj – S). Among the evaluated configurations, Hex adj – P was most effective in bringing down the pollutants to permissible limits. Hex adj – P achieved the highest removal of total hardness (TH) (88 %), F ‐ (89 %), Cl ‐ (72 %) and produced 6.2 times higher power density (PD) than the Conv MDC. The membrane characterization (XRD & FESEM) confirmed minimal fouling and scaling in Hex MDC. This study thus proves the feasibility of treating GW using MDC and highlights the significance of reactor architecture in a treatment process. • A hexagonal configuration of MDC (Hex MDC) is used for groundwater treatment • Hex MDC outperformed conventional MDC (Conv MDC) in ion removal and power production • Total hardness, fluoride, and chloride was brought down to permissible limits by Hex MDC • Parallel connection produced highest power output in both the reactors • Hex MDC generated a 6.2-fold higher power than Conv MDC