Sustainable leachate pre-treatment using microbial desalination cell for simultaneous desalination and energy recovery

Leachate treatment technologies struggle with low treatment efficiencies due to complex and toxic chemicals in leachate. Therefore, mixing leachate with low-density wastewater could be beneficial. This research studied the feasibility of pretreating a mixture of leachate and municipal wastewater (1:4) in a microbial desalination cell (MDC) for the first time. The study examined the MDC potential in removing organics and NH₃-N from leachate-wastewater mixture along with measuring the desalination efficiency and energy recovery at different applied external resistance (R_ext). The results showed that MDC-1 (at R_ext = 1 Ω) showed a higher desalination rate (DR) (35.71 mg/h) and higher NH₃-N removal (36%) with lower COD removal (28%) compared to MDC-100 (at R_ext = 100 Ω) with DR = 17.98 mg/h, NH₃-N removal of 10% and COD removal of 78.26%. The results revealed that R_ext could regulate the pollutants (organics, NH₃-N) removal and desalination efficiency. The lack of soluble organics could also result in significant discrepancies in bioelectrochemical performance. MDC-100 showed four times higher energy output (5.63 W·m⁻³) compared to MDC-1 (1.39 W·m⁻³), while MDC-1 showed five times higher columbic efficiency (29.3%) compared to MDC-100 (5.52%). Future studies should investigate the best MDC configurations for the optimum leachate-wastewater ratio for sustainable leachate treatment.