Microbial Desalination Cell for Arsenic Removal: Influence of Dissolved Oxygen, Temperature, and Retention Time

Arsenic contamination of drinking water sources poses a critical global public health threat, with millions of people in developing regions exposed to concentrations far exceeding the World Health Organization guideline value of 10 μg/L. Conventional removal technologies are frequently constrained by high operational costs, chemical dependency, and secondary waste generation, creating an urgent need for sustainable, energy-efficient alternatives suitable for resource-limited settings. This study evaluated the performance of a laboratory-scale microbial desalination cell for arsenic elimination from contaminated water by systematically investigating the effects of dissolved oxygen concentration (2–6 mg/L), temperature across psychrophilic (5–15°C), mesophilic (25–30°C), and thermophilic (50–60°C) regimes, hydraulic retention time (30–120 minutes), and initial arsenic concentrations of 100–600 μg/L, with performance further validated against synthetic wastewater and real drinking water samples collected from the Bardsir region of Kerman Province, Iran. Optimal operating conditions of 6 mg/L dissolved oxygen, mesophilic temperature, 600 μg/L initial arsenic concentration, and 120 minutes retention time yielded a maximum arsenic removal efficiency of 75% with an open-circuit voltage of 0.72 V, while efficiencies of 67% and 57% were achieved from real drinking water and synthetic wastewater, respectively. The findings demonstrate that the microbial desalination cell is a technically viable, low-energy, and sustainable platform for arsenic removal, offering particular promise for decentralised treatment applications in arsenic-affected communities where conventional infrastructure is unavailable, though multi-stage treatment is recommended to meet drinking water quality standards.