Electrodeionisation of water

Why Electrodeionisation?

The production of ultrapure water uses a combination of membrane separation and ion exchange processes. EDI is a process that combines semi-permeable membrane technology with ion exchange to provide a highly efficient demineralisation process. Unlike traditional ion exchange systems, an EDI system does not require chemicals.

Waterbehandelingsinstallatie voor ultrapuur water (EDI)
Waterbehandelingsinstallatie bij een klant van Grünbeck Waterbehandeling voor ultrapuur water

What is EDI (Electro Deionisation)?

Electro Deionisation (EDI) is a technique for producing demineralised (demi water) / Ultra Pure Water (UPW) and consists of a combination of membrane filtration and an ion exchange unit. The EDI process produces industrial process water of very high purity, using less than 95% of the chemicals used in conventional ion exchange processes. With the EDI system, membranes and electricity replace the large amounts of litres of acid and base chemicals that the old processes required on a daily basis.

How does Electro Deionisation work?

By passing a direct voltage through the EDI module, the ions in the water supply are transported along the surface of the ion exchange resin to the ion-selective membrane. Ions pass through the membrane and reach the barrier chamber. Here they are removed. All that remains is demineralised water.

Direct current divides water into H+ and OH- ions. These then regenerate the ion exchange resin. Since the selective membrane only allows ions to pass through, a small part (5%) of the water supply is used to remove the ions from the barrier chamber in the concentrated flow.

As an alternative to traditional ion exchange processes, EDI brings advances in both the energy and operating costs of water treatment and purification technologies. Environmental benefits are also realised by avoiding and removing acidic and caustic chemicals brought into the field by eliminating the regular regeneration requirements for ion exchange resins.

Medewerker van Grünbeck bezig met montage van een waterbehandelingsinstallatie

Advantages of Electro Deionisation

Grünbeck EDI systems have many important features and benefits, including:

  • Simple and continuous operation
  • Complete elimination of regenerated chemicals
  • Economical operation and maintenance
  • Low energy and salt consumption
  • Environmental friendliness, safety and reliability
  • Little need for automated valves or complex control sequences that require operator supervision
  • Takes up little space
  • Produces very pure water with a constant flow
  • Removes completely dissolved inorganic particles
  • Removes more than 99.9% of ions from water when combined with reverse osmosis pretreatment

Disadvantages of Electrodeionisation

EDI also has disadvantages, namely:

  • EDI cannot be used in water with a hardness greater than 1. This is because the concentrated water crusts the calcium carbonate in the camera and limits its effect.
  • Cleaning pre-treatment is required.
  • Carbon dioxide passes freely through the RO membrane, increasing the conductivity of the water. Ionic species formed from carbon dioxide gas reduce the leakage resistance of water produced by EDI. Management of CO2 in the water is usually done in two ways. Either adjust the pH of the water to allow the RO membrane to release ionic species, or use stripping gas to remove carbon dioxide from the water.
Waterbehandelingsinstallatie met omgekeerde osmose installatie en een EDI voor ultrapuur water

EDI systems of Grünbeck

EDI systems offer a wide range of benefits. These include high water efficiency and very pure water without the use of chemicals.

Are you interested in, or do you have questions about electro deionisation? Then please contact info@gruenbeck.nl! Grünbeck has been a specialist in water treatment for many years, and our experts will be happy to answer your questions.


The knowledge article on electrodeionisation of water is also available in Dutch

EDI waterbehandelingsinstallatie voor ultrapuur water


100 – 2700L

Kleine ton voor waterbehandeling van ultrapuur water van Grünbeck Waterbehandeling

Mixed bed filter desaliQ:BA

600 – 2000L

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