Introduction to the main processes of deionized water production equipment

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This post was last edited by hesonchang214 on 2019-11-2 08:32. The first method involves using cation-anion exchange resins to produce deionized water; after this process, the conductivity of the water can be reduced to below 10 us/cm. Further treatment with a mixed-bed resin can then bring the conductivity down to below 1 us/cm. However, the water produced by this method is extremely costly, and it contains too many particulate impurities, failing to meet the desired standards. It is now used less frequently. 　　The second method: pretreatment (i.e., sand-carbon filter + precision filter) + reverse osmosis + mixed-bed process. This approach is widely used nowadays, as the investment cost for reverse osmosis is not high; it can remove over 90% of the ions in water. The remaining ions are then removed through ion exchange in the mixed bed, resulting in a conductivity of the output water of around 5–10 us/cm. This is the popular method at the moment. 　　Third method: Two-stage reverse osmosis is used. The process is as follows: tap water → multi-media filter → activated carbon filter → water softener → intermediate water tank → low-pressure pump → precision filter → first-stage reverse osmosis → pH adjustment → mixer → second-stage reverse osmosis (with positively charged reverse osmosis membrane surface) → pure water tank → pure water pump → microporous filter → point of use.

Fourth method: Pre-treatment uses reverse osmosis just like the second method, but the mixed-bed used later is replaced by EDI continuous desalination membrane modules; thus, there is no need for acid or alkali to regenerate the resin, as regeneration is carried out electrically. This makes the entire process completely pollution-free, and the quality of the treated water can reach over 15M. However, this method requires a higher initial investment, but has low operating costs. Make appropriate investments based on the circumstances of each company.