Pilot-scale membrane capacitive deionization for water reclamation: Commissioning, performance benchmarking, and long-term assessment

With the continued advancement of membrane capacitive deionization (MCDI) technology, research has focused not only on exploring its practical applications but also increasingly on the development of pilot-scale implementation. This study presents the first successful development of a decision framework for the pilot-scale MCDI water reclamation process, providing a structured framework for MCDI system design and operation. This pilotscale MCDI-based water reclamation process was demonstrated to reclaim secondary effluent from a domestic wastewater treatment plant continuously and in real time. During the benchmark procedure, a 400-s charging time and a 120-s discharging time were selected on the basis of the trade-off between MCDI performance aspects. The long-term assessment further validated the effectiveness and robustness of the optimized operating protocols. With treatment capacity of 21.1 cubic meters per day (CMD), the MCDI unit demonstrated stable ion removal efficiency exceeding 80%, low energy consumption (0.21 +/- 0.07 kWh/m3), and high water recovery (77%) with an acidic cleaning frequency of 2.25 times per day. However, challenges such as organic fouling or mineral scaling have been observed, potentially impacting system longevity over time. Overall, the decision framework and operating protocols for the MCDI-based reclamation process were validated by findings from experimental investigations. The high quality of reclaimed water from secondary effluent at the domestic wastewater treatment plant (DWTP) highlights the potential of MCDI as a scalable and efficient technology for sustainable water reclamation.