What is electrodeionization?

Electrodeionization (EDI) is a continuous water purification technology that removes dissolved ions using ion-exchange resin, ion-selective membranes, and an electrical field. It is commonly installed after reverse osmosis to produce high-purity or ultrapure water without chemical resin regeneration.

How does an EDI system work?

An EDI system uses a direct-current electrical field to move positively and negatively charged ions through ion-exchange resin and selective membranes. The ions are transferred into concentrate streams, while water splitting continuously regenerates the resin inside the module.

Does EDI use chemicals?

EDI does not require the periodic acid and caustic chemical regeneration used by conventional mixed-bed deionisation systems. It uses electricity and water to maintain the ion-exchange resin in a regenerated state.

Why is RO used before EDI?

Reverse osmosis removes most of the dissolved salts and contaminants before water reaches the EDI system. This reduces the ionic load on EDI and allows it to focus on removing the remaining trace ions.

What is continuous electrodeionization?

Continuous electrodeionization is an EDI process in which ion removal and resin regeneration occur continuously while the system is operating. Unlike conventional deionisation, it does not require regular shutdowns for chemical regeneration.

Electrodeionization (EDI) for Ultrapure Water | Chemical-Free Purification