Continuous electrodeionization (CEDI) is a process that involves a combination of ion exchange resins and membranes with a flow of electric current to remove ions from water. Standard designs for the production of Purified Water (PW), Water for Inyection (WFI) and High Purity Water usually includes a reverse osmosis stage followed by CEDI. This configuration allows the production of water with ion concentrations close to, o lower than, detection limits. CEDI is widely accepted for the production of high purity water for the pharmaceutical industry, as well as for microelectronics and energy production.
EDI regenerates with no use of chemicals. Therefore, operation is safer since no dangerous chemicals are handled, stored or manipulated. For this same reason no neutralization of regenerants is needed.
EDI is a continuous process that automatically regenerates the resins due to the electrical field generated by the electrical current used for operation. This differs with ion exchange operation, since it doesn't need to be taken out of operation in order to perform a regeneration. Since regeneration is continuous, water quality is uniform, and no increasing leackage occurs, as it usually does with ion exchange, as resins get saturated.
The electric field also creates a stable environment inside the CEDI cell, in terms of microbiology, inhibiting bacterial and other microorganism’s growth.
The CEDI system has significantly lower operational costs than conventional Ion Exchange. A small amount of energy is used to obtain high purity water. The lack of acid or caustic soda for regeneration translates into a lower dependence on the operator, reducing then the expenses associated to manpower. CEDI initial investment is similar to traditional Ion Exchange (there’s no need for chemical storage, chemical pumping systems, equipment for neutralization, among others).
There is no need for a “Twin Configuration” with CEDI because due to its modular construction, one of the modules can be removed from the equipment to perform maintenance operations, while the rest remain operating.
CEDI footprint is much lower than a conventional treatment unit.
CEDI are highly recommendable alternatives for the following treatments:
- Ion Exchange deionization.
- Second stage of Reverse Osmosis.