Electro Deionization

Additional Details

Electro deionization or EDI, is a continuous and chemical-free process of removing ionized and ionizable species from the feed water using DC power. EDI is typically used to polish reverse osmosis (RO) permeate and to replace conventional mixed bed ion exchange, which eliminates the need to store and handle hazardous chemicals used for resin regeneration and associated waste neutralization requirements. 

The patented EDI module utilizes a unique, leak free, low maintenance spiral wound design containing membrane (see below) and ion exchange resins, sealed in a high-strength fiberglass reinforced plastic (FRP) pressure vessel. EDI modules optimize performance, maintain continuous product quality and can produce up to 18 M -cm high-purity water with high silica and boron rejection.

Electro deionization (EDI) is a water treatment process that removes ionizable species from liquids using electrically active media and an electrical potential to effect ion transport. It differs from other water purification technologies such as conventional ion exchange in that it is does not require the use of chemicals such as acid and caustic. EDI is commonly used as a polishing process to further de ionize Reverse Osmosis (RO) permeate to multi-mega ohm-cm quality water. 

The continuous electro deionization (EDI) process, is distinguished from other electrochemical collection/discharge processes such as electrochemical ion exchange (EIX) or capacitive deionization (Cap DI), in that EDI performance is determined by the ionic transport properties of the active media, not the ionic capacity of the media. EDI devices typically contain semi-permeable ion-exchange membranes and permanently charged media such as ion-exchange resin. The EDI process is essentially a hybrid of two well-known separation processes - ion exchange deionization and electro dialysis, and is sometimes referred to as filled-cell electro dialysis.