Ion Migration
When a DC electric field is applied, cations and anions move toward electrodes of the opposite charge.
EDI | Electrodeionization
Operating Principle
EDI is a high-purity water treatment technology that combines ion-exchange membranes, ion-exchange resins and a direct-current electric field to continuously remove residual ions from water.
Ion-exchange resin fills the dilute chambers between cation-exchange membranes (CEMs) and anion-exchange membranes (AEMs). When a DC electric field is applied, cations move toward the cathode (−) and anions toward the anode (+).
The ions selectively pass through their respective ion-exchange membranes into the concentrate chambers. Ion concentrations in the dilute chambers continually decrease, producing high-purity water.
Within the EDI module, H⁺ and OH⁻ produced by electric-field-induced water dissociation continuously regenerate the ion-exchange resin. Unlike conventional ion-exchange processes, this enables continuous high-purity water production without periodic acid or alkali regeneration.
Selective Separation
Ion-exchange membranes selectively allow ions of a particular charge to pass into the concentrate chambers, reducing ion concentrations in the dilute chambers.
Continuous Regeneration
Hydrogen and hydroxide ions produced by water dissociation continuously regenerate the resin, enabling high-purity water production without separate chemical regeneration.
EDI Advantages
Continuous High-Purity Water Production
Simultaneous ion removal and resin regeneration enable continuous high-purity water production without stopping operation.
No Regeneration Chemicals
Periodic acid and alkali regeneration is unnecessary, reducing chemical consumption, regeneration wastewater and the operational demands of chemical storage and handling.
Stable Product Water Quality
Maintains consistent high-purity water quality under appropriate pretreatment and operating conditions.
Compact System Design
A simple, compact configuration for polishing downstream of RO.
Easy Automation and Maintenance
Suitable for continuous automated operation, with minimal separate chemical-handling equipment.
EDI Equipment
EDI Applications
Semiconductors & Displays
Ultrapure water (UPW) production, cleaning water, and water for electronic components and precision materials manufacturing
Pharmaceuticals & Biotechnology
Purified water systems, high-purity water for pharmaceutical and bioprocesses, and medical purified water
Power & Energy
Boiler feedwater, high-purity water for combined-cycle and cogeneration plants, and demineralized water for high-pressure steam systems
Other High-Purity Water Applications
Fine chemicals, battery materials, laboratory and analytical water, and alternatives or supplements to mixed-bed processes
EDI Modules and Systems for Your Feedwater
As the exclusive SnowPure distributor in Korea, we support everything from module selection to system design.
