What Is RO-Electrodeionization?

Electrodeionization (EDI), also known as Continuous Electrodeionization (CEDI), is an advanced water purification technology that continuously removes ionized and ionizable impurities from water using direct current (DC) power—without the use of chemicals.

Unlike traditional mixed-bed ion exchange systems that require periodic regeneration with hazardous acids and bases, EDI is a chemical-free solution that combines ion exchange resins with electrically active membranes and a DC electrical field. This process efficiently polishes reverse osmosis (RO) permeate to deliver consistent, ultra-pure water.

Benefits of RO-EDI Water Purification

Chemical-Free Operation – No acid or caustic regeneration required
Continuous Process – No shutdowns or downtime for regeneration
Low Operating Costs – Reduced consumables, disposal, and labor
Environmentally Friendly – No hazardous chemical storage or waste
Consistent Water Quality – Resistivity often >15 MΩ·cm
Compact Footprint – Smaller resin volume, high efficiency
Bacteriostatic Environment – Inhibits bacterial growth inside the module

EDI Membrane Graphic

How RO-Electrodeionization Works

EDI modules consist of multiple chambers filled with ion exchange resins, separated by ion-exchange membranes. As water flows through the chambers:

Ionized impurities are attracted by the applied electrical field.
Ions migrate across membranes into concentrate streams.
Purified water continues through the system, free from dissolved inorganics.
The resins are continuously regenerated by the electric field, eliminating the need for chemical regeneration.

Because contaminants are diverted into separate concentrate channels, the resins are not exhausted and can operate for years with minimal maintenance.

Applications of RO-EDI/CEDI Systems

Our EDI systems are ideal for any industry requiring high-purity water without chemical regeneration:

Electronics Manufacturing
Pharmaceutical & Biotech
Power Generation & Boiler Feed Water
Laboratory & Analytical Applications
Cooling Tower Makeup Water
Food & Beverage Production

Why Choose ALSI for Your RO-EDI System?

Reliable, Long-Term Performance
Eco-Friendly, Sustainable Water Treatment
Expert Support for System Integration and Maintenance
Engineered for Compatibility with RO and Pretreatment Systems

Whether you’re looking to upgrade an aging ion exchange system or build a new high-purity water treatment train, our EDI solutions offer unmatched performance, cost-efficiency, and regulatory peace of mind.

Looking for a Rental?

Short or Long-Term rental units available
Delivery and Startup Services available
Service and Maintenance included with rental

ALSI gives you the flexibility to either purchase a capital RO-EDI system or rent exactly what you need. Our short- and long-term rentals include fast delivery, full startup support, and worry-free service and maintenance, so you stay focused on production while we handle the rest.

Talk to a Water Treatment Expert

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EDI modules consist of multiple chambers filled with ion exchange resins, separated by ion-exchange membranes. As water flows through the chambers:

Ionized impurities are attracted by the applied electrical field.
Ions migrate across membranes into concentrate streams.
Purified water continues through the system, free from dissolved inorganics.
The resins are continuously regenerated by the electric field, eliminating the need for chemical regeneration.

Because contaminants are diverted into separate concentrate channels, the resins are not exhausted and can operate for years with minimal maintenance.