Non-Pressurized Counter-Current Regeneration Cation-Anion Exchanger

The non-pressurized counter-current regeneration ion exchanger retains all the advantages of counter-current regeneration while eliminating the need for a pressurization system, simplifying operation, and reducing both investment and operating costs. As such, it is currently one of the more advanced devices in desalination treatment. By loading different types of resin into the column, it can function as a strong-type bed, weak-type bed, dual-layer bed, etc., enabling the formation of an economically rational desalination process and achieving optimal technical and economic outcomes.
The designed operating flow rate for this exchanger is 15-20 m/h for Φ200-Φ800 models, and 20-30 m/h for Φ1000-Φ3000 models. The regeneration flow rate is 2 m/h for Φ200-Φ800 models, and 5-7 m/h for Φ1000-Φ3000 models. The backwash flow rate is 10-15 m/h for cation beds and 8-10 m/h for anion beds.
To ensure extended water production periods and minimize regeneration frequency, the total influent salt content should be below 500 mg/L. When this value is exceeded, the use of a pre-electrodialysis unit is more appropriate.
When cation and anion exchangers are combined to form a mixed-bed system, it is advisable to install a CO₂ removal unit between them if the influent alkalinity (HCO₃ content) exceeds 50 mg/L, as this facilitates more effective dealkalization.