Abstract
Electrodeionization (EDI) is a membrane desalination process that is used in the production of ultrapure water (UPW). Unlike ion-exchange resin demineralization, EDI is a continuous process which does not require acid or caustic regeneration. Also EDI is a fairly simple process which requires little operator attention and little maintenance.
One of the successes of EDI is the high removal ratio of weakly ionized species. Weakly ionized species such as boron and silica break through ion-exchange resin relatively earlier but it is hard to detect the breakthrough by observing conductivity, and moreover, boron monitor and silica monitor are relatively expensive especially for small UPW production. For these reasons, management of leakage of weakly ionized species from ion-exchange resin is always an issue. On the contrary, it does not the case in EDI operation since it can operate continuously.
