Capacitive Deionization Water Desalination Technology, Process Optimization and Cost Analysis - A Review

Capacitive deionization is an emerging electrochemical technology employed in water desalination applications. Multiple water desalination technologies include reverse osmosis, multi-stage flash, humidification-dehumidification, and nanofiltration. Capacitive deionization is appreciably increased the desalination efficiency compared to other technologies while promising energy-efficient and cost-effective operation. In the CDI system, the charged ions are extracted from feedwater by applying an electrical voltage across electrodes, in which the charged ions are attracted to the oppositely charged electrodes. This paper demonstrates the concept of capacitive deionization (CDI), the components of CDI cell, working principal, and performance metrics for the CDI system. Furthermore, the paper reviews the state of technology of the CDI cell and the development of the system since the mid-1960, including the concepts of membrane and flow electrode CDI. Finally, a cost analysis framework of CDI, MCDI, and FCDI is demonstrated based on the Levelized cost of water.