The Process and Water Quality Specialists
In contrast to other membrane types, the ED process applies an electric potential that moves dissolved salt ions (e.g. (+) ions are attracted to the (–) electrode) through an electrodialysis stack consisting of alternating layers of cationic and anionic ion exchange flat sheet membranes, creating alternate channels of desalted product water and concentrated reject water. A modification of the ED process; termed as EDR (electrodialysis reversal), reverses the polarity of the applied electrical potential on the stack, periodically, to minimize the effects of inorganic scaling and fouling by converting product channels into concentrate channels. EDR is most attractive for the desalination of brackish water and in cases where TOC removal and microbial control are not important. Click here to see a working diagram of ED process.