02
Track 02 · Water treatment
EDI: electrodeionization
Continuous deionization after RO, with no acid or caustic regeneration.
How it works
EDI combines ion exchange resin, ion-selective membranes and direct current. Ions cross the membranes into a concentrate compartment. The current splits some water into H⁺ and OH⁻, which regenerate the resin inside the module.
The system therefore runs continuously, with no chemical regeneration stops. Different needs suit different types of EDI, so I select by product quality and operating conditions.
When to use it
- You need ultrapure water for electronics, microchips, thermal power, cleanrooms or pharmaceuticals.
- You want stable quality without storing and handling acid and caustic on site.
- An RO stage upstream already meets the feed requirements of the module.
Common mistakes
- Feed water above the limits for hardness, CO₂, silica or chlorine, scaling and shortening the life of the module.
- Applying power before flow is stable, or starting and stopping in the wrong order.
- Imbalance between product and concentrate flows.
- Not trending voltage, current and differential pressure.
- Leaving a module idle for long periods without proper preservation.
Related notes
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