Integration of photovoltaic energy supply with membrane capacitive deionization (MCDI) for salt removal from brackish waters.

Capacitive de-ionization (CDI) systems are well-known for their low energy consumption making them suitable for applications powered by renewable energy. In this study, CDI technology is, for the first time, integrated with a suitably-scaled, stand-alone, renewable power system comprising photovoltaic panels and battery storage. Guidelines for designing and sizing such power systems are proposed including determining electrode charging current, PV panels and battery capacity. A 1 kW pilot plant was designed, constructed and operated to verify the proposed guidelines. Using the pilot plant, the total energy consumption of the system has been evaluated with different electrode charging currents and influent flow rates and the relationship between these parameters analyzed. This analysis has enabled the development of practical design guidelines for bulk water treatment with MCDI electrodes. The results of this study show that use of photovoltaic-powered MCDI water treatment, particularly when combined with energy recovery, is competitive against more mature water-treatment technologies for particular applications and at particular locations.