EDI RO Ultrapure Water Treatment
EDI-RO ultrapure water treatment systems combine electrodeionization (EDI) and reverse osmosis (RO) technologies to provide an industrial water treatment solution for the continuous and stable production of high-purity water. It has become a core process for ultrapure water production in industries such as semiconductors and pharmaceuticals.
Reverse Osmosis (RO) serves as the primary desalination step, removing approximately 99% of dissolved ions, organics, and microbes. The two-pass RO ensures feed water quality for the EDI module meets stringent requirements.
Electrodeionization (EDI) acts as the final polishing stage. It uses a direct current electric field to drive ion migration through ion-exchange membranes and resin, continuously producing high-purity water without the need for chemical regeneration.
Key Features & Advantages
Compared to traditional mixed-bed ion exchange (MB), the EDI-RO combination offers significant operational benefits:
| Feature | EDI-RO Integrated System | Traditional Mixed-Bed Ion Exchange |
|---|---|---|
| Operation Mode | Continuous production, no downtime for regeneration. | Batch process. Requires periodic (days/weeks) shutdown for chemical regeneration. |
| Chemical Use | No acids or alkalis needed for regeneration. Eliminates hazardous chemical handling and waste disposal. | Heavily reliant on acids and alkalis for resin regeneration, with associated safety and environmental costs. |
| Water Quality Stability | Produces consistently high-purity water (typically 15-18 MΩ·cm resistivity) with no end-of-cycle quality decay. | Water quality declines through the service cycle, peaking after regeneration and falling before the next. |
| Automation & Space | Highly automated, easy PLC integration. Compact, modular design with smaller footprint. | Complex regeneration procedure often requires manual operation. Larger equipment footprint. |
| Operating Cost | Higher initial capital investment, but lower long-term operating cost (no chemicals, minimal waste, less labor). | Lower initial investment, but higher recurring operating costs (continuous chemical purchase, waste neutralization, and labor). |
Critical Feed Water Requirements for EDI:
The upstream RO system must condition the feed water to meet strict EDI inlet specifications:
Conductivity: Typically <40 μS/cm, optimal at <10 μS/cm.
Hardness (as CaCO₃): <1.0 ppm to prevent scaling.
Silica (SiO₂): <1.0 ppm, preferably <0.5 ppm.
Total Organic Carbon (TOC): <0.5 ppm.
Free Chlorine/Oxidants: <0.05 ppm to prevent oxidative damage to membranes and resin.
Fully automatic large-scale EDI commercial water purifier | |
Process | Raw water – multi-media – reverse osmosis – EDI |
Water output | 250-10000L/H |
MCotroller | Automatic |
Voltage | 220V/380V |
Equipment Size | Customized |
Device Material | Food grade FRP/stainless steel |