Ion exchange is a molar reaction of equal charge between ions in water and ions on ion exchange resin.

Composite bed: Using two exchangers, the anion and cation exchange resins are loaded into their respective exchangers according to the design requirements. The raw water is first treated with cation exchangers, and cations such as Ca2+, Mg2+, K+, Na+in the water are adsorbed by the exchangers. The exchangeable H+on the exchangers is replaced by the water and forms inorganic acids with the anions in the water; The effluent passes through an anion exchange agent, where anions such as SO42-, CL -, HCO3-, etc. are adsorbed by the exchange agent. The exchangeable ion OH - on the exchange agent is replaced in the water and combines with H+in the water to form H2O.

The water treated by the above-mentioned anion and cation exchangers removes the salt in the water, which is the desalination treatment of the first stage double bed. The effluent water quality is ≤ 10us/cm.

The regeneration cycle is determined based on the quality and water consumption of the raw water. Generally, tap water can be regenerated for about one cycle. The required regeneration solution is divided into hydrochloric acid and alkali, with hydrochloric acid used to regenerate cations. Mix one liter of hydrochloric acid (with a concentration of over 30%) with each liter of cations, and dilute it with a jet mixer to a concentration of about 6%. Let it wash slowly for half an hour, and then rinse the acid solution clean again.

Generally, a 99% concentration of caustic soda is mixed with water, with a concentration of about 30%, to cool it down, and then diluted into the anion resin layer through a jet injector. It is discharged in the middle for about half an hour, and then rinsed with a large amount of raw water until the alkaline solution is completely washed, usually for about 50 minutes. Regeneration completed.