ELECTRONIC DEIONIZATION (CEDI) WATER TREATMENT
Continuous Electronic Deionization (CEDI) is an advanced water purification technology used to remove ions from water through an electrochemical process. Also known as continuous electrodeionization, CEDI is commonly used in various industries where high-purity water is required, such as in pharmaceuticals, electronics manufacturing, power generation, and laboratory applications.
CEDI is an evolution of the more traditional ion exchange process, which involves using resin beds to exchange ions in the water with ions of similar charge on the resin beads. CEDI enhances this process by using ion-exchange membranes and an electric field to continuously remove ions from the water without the need for chemical regeneration of the ion exchange resin.
CONTINUOUS ELECTRONIC DEIONIZATION
Continuous Electronic Deionization (CEDI) offers consistent high-purity water without the downtime associated with regeneration cycles or swapping out large resin tanks. Its continuous operation, combined with the absence of chemical regenerants, makes it a preferred choice in industries where consistent and reliable water quality is crucial for process water applications. Several thousand CEDI treatment systems have been installed over the past two plus decades and these numbers continue to grow as more companies are looking for a sustainable alternative to the strong acid and strong base chemicals that are used to regenerate traditional mixed bed deionizing resins.
HOW CONTINUOUS ELECTRONIC DEIONIZATION WORKS
Ion Exchange Membranes: CEDI systems consist of alternating cation-exchange and anion-exchange membranes. These membranes are selective, allowing only either positively charged ions (cations) or negatively charged ions (anions) to pass through.
CEDI units are typically configured as a stack of alternating cation and anion exchange membranes. Feed water flows through the stack in a controlled manner.
Electric Field: A direct current (DC) electric field is applied across the membranes in the stack. This electric field creates a migration of ions towards their respective exchange membranes. Opposites attract so cations are drawn toward the anion-exchange membranes, and anions are drawn toward the cation-exchange membranes.
As the water flows through the stack, ions migrate across the exchange membranes according to their charge. Positively charged ions are removed by the anion-exchange membranes, and negatively charged ions are removed by the cation-exchange membranes.
The continuous migration of ions through the membranes results in a continuous purification process. The effluent, or permeate, from the CEDI unit is depleted of ions, resulting in high-purity water suitable for various applications.
One of the key advantages of CEDI is that it operates without the need for chemicals or frequent regeneration cycles, as required by traditional ion exchange systems. This makes CEDI more efficient and environmentally friendly.
Depending on the specific application, the purified water from a CEDI unit might undergo further treatment steps, such as ultraviolet (UV) disinfection, ozone purification, or polishing filters, to ensure the desired level of purity.