Product Overview
For decades, mixed-bed ion exchange technology has been the standard for ultra-pure water preparation. However, this method requires periodic regeneration, which consumes large amounts of chemicals (acid and alkali) and pure water, leading to environmental concerns. As a result, there is a growing need to develop acid- and alkali-free ultra-pure water systems.
Traditional ion exchange can no longer meet the demands of modern industry and environmental protection. This has led to the development of Electrodeionization (EDI) technology, which combines membranes, resin, and electrochemical principles to revolutionize water treatment. EDI eliminates the need for chemical regeneration, making it environmentally friendly and compliant with global environmental standards.
Since its industrialization in 1986, thousands of EDI systems have been installed worldwide, particularly in industries such as pharmaceuticals, semiconductors, power generation, and surface cleaning. EDI is also widely used in wastewater treatment and beverage production.
EDI devices are used in conjunction with reverse osmosis systems, replacing traditional mixed-bed ion exchange (MB-DI) to produce stable deionized (DI) water. Compared to mixed-bed ion exchange, EDI technology offers the following advantages:
1. Consistent High Quality: Produces water with a resistivity of up to 17 MΩ·cm (0.058 µS/cm).
2. Fully Automated Operation: No manual intervention required.
3. No Downtime for Regeneration: Continuous operation without interruptions.
4. Chemical-Free Regeneration: Eliminates the need for acid and alkali chemicals.
5. Low Operating Costs: Reduced chemical and maintenance expenses.
6. Compact Design: Requires minimal workshop space.
7. Environmentally Friendly: No wastewater discharge.
EDI technology represents a sustainable and efficient solution for modern ultra-pure water production, meeting the needs of both industry and environmental protection.
Working Principle of Electrodeionization
Electrodeionization (EDI) operates by using an electrical current. This current forces contaminant ions in the feed water to continuously migrate out of the water and into the reject stream. At the same time, the resin bed is constantly regenerated with H+ (hydrogen) and OH- (hydroxyl) ions produced from water splitting. The patented flow process of the dilute and concentrate streams makes the Omexell module truly unique.
1. Feed Water (Dilute Stream) Flow
The feed water, which is the dilute stream, enters the Omexell module from the bottom. It is then directed into vertically spiraled cells called the 'D' (dilute) chambers. This dilute stream flows vertically through ion - exchange resins. These resins are positioned between two membranes: an anion membrane, designed specifically to allow only anions to pass through, and a cation membrane, which permits only cations to migrate.
2. Concentrate Flow
Concentrate enters the module through the central pipe from below. It is diverted into spirally - flowing cells known as the 'C' (concentrate) chambers.
3. Role of DC Current
A direct current (DC) is applied across the cells. This DC electrical field causes a small proportion of water molecules (H2O) to split into hydrogen (H+) and hydroxyl (OH-) ions. These H+ and OH- ions attach to the cation and anion resin sites, constantly regenerating the resin. Hydrogen ions carry a positive charge, and hydroxyl ions have a negative charge. Due to their attraction to the cathode or anode, they migrate through their respective resins, then pass through their corresponding permeable membranes, and finally enter the concentrate chamber. Cation membranes are only permeable to cations and prevent anions and water from passing. Similarly, anion membranes are only permeable to anions and block cations and water.
4. Contaminant Removal Process
Contaminant ions dissolved in the feed water attach to their respective ion - exchange resins, displacing H+ and OH- ions. Once in the resin bed, these contaminant ions join the migration of other ions and pass through the membrane into the 'C' chambers. The contaminant ions get trapped in the 'C' chamber and are carried away. The feed water continues to flow through the dilute chamber, where it is purified. The purified water is collected at the outlet of the "D" chambers and exits the EDI module. All the product flows from the EDI module are gathered and leave the system.
The condition of influent water quality
TEA(contain CO2 ) <25mg/LasCaCO3
PH 5-9
Water hardness < 0.5 mg/LasCaCO3
Silicon <0.5mg/L
TOC <0.5 mg/L
Remaining Cl <0.05mg/L
Fe,Mn,H2S <0.01 mg/L
Influent Water pressure 30-100PSI
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