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Continuous Electro Deionization

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CEDI (Continuous Electro Deionization) is a continuous electrochemical process that is typical implemented downstream a Reverse Osmosis system. CEDI modules consist of many flow compartments formed by alternating cat-ion and an-ion exchange membranes. Feed water enters the module and is distributed throughout the product and reject compartments. Under the influence of DC voltage, ions in the product compartments are transferred to the reject compartments for disposal. Both compartments are resin filled. As the water in the product compartments become free of ions, the DC voltage splits water into hydrogen and hydroxyl ions, which in turn regenerate the ion exchange resins.

The water passing through the product compartments is deionized to purified water, while the rest of the water is flowing into the reject compartments. This water takes away concentrated salts and small amounts of gases formed on the electrode surfaces. The reject water exiting the CEDI unit can be re-used and mixed with the RO feed water in a vented break tank.