Continuous Electro-Deionisation (CEDi) is the latest generation of ion exchange technology. This continuous process produces high purity water without the need for regenerant chemicals.
Continuous Electro-Deionisation (CEDi)
It is mainly used for deionisation downstream of reverse osmosis for polishing and removal of carbon dioxide, silica and total organic carbons (TOC).
CEDi systems use ion exchange membranes, ion exchange resins and electricity to produce consistent high quality water with no regeneration downtime. When fed with RO product water, CEDi systems achieve better than 99.5% salt removal and produce up to 0.055 µS/cm conductivity water.
Principles of CEDi:
- Feedwater entering the system flows inside resin/membrane compartments. The stream flows parallel to the membrane surface.
- Resins capture dissolved ions.
- Electric potential drives capture cations through cation membranes and capture anions through anion membranes.
- Cation-permeable membranes transport cations out of the diluting compartment, but prevent anions from leaving the concentrating compartment.
- Anion-permeable membranes transport anions out of the diluting compartment, but prevent cations from leaving the concentrating compartment.
- A waste stream flushes concentrated ions from the system.
- Product water leaves the system.