EDI system - EMEC - Que Vo Bac Ninh Industrial area

WHAT IS EDI WATER?

EDI (Electrodeionization) is the process of elimination of ions in water by electrolysis, usually by using electrolysis of electrolysis of water (separation of H2O molecules into H + and OH- ions). With DI technology, there is no need to use chemicals like acid and sodium to regenerate.
EDI is a pure water treatment system, commonly used in combination with reverse osmosis RO to form a clean water treatment system, replacing the ion exchange equipment of traditional water treatment technology. In EDI technology, water supply requires 0.025-0.5MΩ · cm resistance, fully reverse osmosis equipment can meet the requirements. Ultra-clean water through EDI technology has a resistivity up to 18MΩ · cm or more.
The structure and operation principle of the EDI technique
Each EDI module typically consists of five main components: ion-exchange resin, two ion-exchange membranes and two electrodes. There are two types of compartments in the EDI device: the dilution chamber and the concentration chamber. The dilution chamber is an ion exchange resin containing pure water or diluted ions. Concentric cavity is the concentrated area of ions and becomes waste water. Diluted and concentrated compartments separated by ion exchange membranes are anionic exchange membranes and cation exchange membranes.
Typical EDI devices contain interleaved anion exchange membranes and semi-permeable cations. The gap between the membranes is loosened by the pad that contains the flow compartment. An external power source is used at the boundary of the membrane and compartment.
The chambers are subjected to an electric field, bound by an anionic film facing the positive and cationic films facing the cathode and are prevented by the dilution chamber. To facilitate ion transfer, the dilution cavity is filled with ion-exchange resin.
Cations in the water supplied to the dilution chamber are absorbed on the cation exchange resins and transported under the electric field applied to the cathode. When a cation passes through the cationic membrane into the adjacent concentration chamber, its process is blocked by anionic membranes on the other side of the cavity, similar to the anions. As a result, diluted dilapidated ions and concentric chambers contain high concentrations of ions.
The great advantage of EDI technology over DI is that it can perform continuously and does not use chemicals for Resin regeneration.

DEIONIZATION PROCESS IN EDI DEVICE

- Deionization: Removal of ions by cations and anion. Resin cations in the form of hydrogen will remove cations such as Ca ++, Mg ++, S, K +, NH + ... Resin anion in the hydroxide form replaces the anion such as Cl-, HCO3-, SO4-, NO3-, SiO2 ... by ion hydroxide. The result of ion exchange in water is the H + and OH- ions, replacing cation ions and anions in water that combine to form pure water.
- Ion Movement: Unlike ion exchange, when cation resins and anions have replaced all H + and OH ions - they need to be regenerated with acid and caustic soda. With the EDI system, the power supply provides a current between the two poles, the current traveling between the electrodes from the positive to the negative. When the ions are removed from the supply water, the cations are attracted to the cathode, the anions are attracted to the positive. When the feed water is introduced into the EDI system, positively charged ions travel through the cationic resin and move through the cation exchange membrane into the concentration chamber by being drawn to the cathode. Similarly, negatively charged ions travel through the anionic resin and move through the anion exchange membrane into the concentric cavity by being drawn to the anode.
As the ions move through the membranes into the concentric chamber, they can not move to the electrode due to the arrangement of the membrane, the cationic membrane is toward the positive electrode and the anion membrane is on the negative side. Water in the concentrate is waste water containing cations and anions to be removed.
- Regeneration: Unlike conventional ion exchanger, acid and caustic soda are used to regenerate resin. EDI systems do not need to be recycled with chemicals, but instead use the electricity used throughout. EDI module. Electricity causes a small fraction of water molecules to dissociate into hydrogen ions and hydroxide so it continually regenerates cationic resins and anion resins without stopping the device for recycling. As a result, the EDI operation is continuous, the continuous ions are removed and the resin is continuously regenerated by the ionization of the electrolyte.
The water quality after filtration through the EDI system reaches a very high resistivity up to 18MOhm.cm, which satisfies the requirements of pure water for the manufacturing industry.

THE ADVANTAGES

-    EDI technology does not require chemicals to restore ion exchange resin particles in traditional water treatment technology.
-    Continuous operation, Water quality is stable
-    Easy to implement automatic control. No chemical required
-    Not due to recirculation cycle that stopped the machine
-    Recycled water and waste water treatment equipment? High productivity of water (95%)
-    No need to store, dilute acid
-    Safe use, avoid workers exposure to acid
-    Reduce operation and maintenance costs
-    Single unit, can be flexibly combined with different water supply
-    Simple installation, low cost ?
-    Occupy less area

APPLICATION OF EDI TECHNOLOGY IN MANUFACTURING INDUSTRIES

-    Pharmaceutical production
-    Microelectronics
-    Power generation industry
-    Washing technology, surface spraying, electrolysis industry
-    Production of electronic components, IC ...
-    Laboratory
-    Super clean chemical
-    Car polish surface treatment, home appliances
-    Photovoltaic Products
-    Highly technical products
-    Supply to large pressure boiler
-    Paint and plating industry