Electrodialysis, electrodialysis reversal and capacitive deionization technologies

Abstract

The electromembrane process is a designation to describe technologies grounded on ion migration through ion-exchange membranes using the electrical potential gradient as the driving force. In this field, the main processes are electrodialysis, electrodialysis reversal, electrodialysis with the bipolar membrane, electrodeionization, and membrane-capacitive deionization. This chapter presents the operational principles, the transport equations, particularities, applications, and limitations for these electromembrane processes. Their competitiveness, compared to other technologies, depends on a series of conditions such as the quality of the water or wastewater to be treated, the degree of treatment desired, space and energy available for installing the treatment plant, as well as installation and operating costs. Nowadays, electromembrane processes are also applied for product purification and recovery in many industries. However, most uses are due to electro-membrane processes bringing together clean technologies able to change polluted water in drinking water and convert wastewater into a source of reuse water, thus allowing materials recovery.. Thus electromembrane technologies may be chosen as closing-loop methods for zero-discharge processes.