Acidity and alkalinity of desalinated water
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The demineralized water system consists of an activated carbon tank, a softener (anion bed—cation exchange resin), and an RO reverse osmosis membrane. The chloride content in the demineralized water produced by the demineralization system is between 10–20 mg/L, and its pH value is 6–7, indicating a slightly acidic nature. I wonder if it’s normal?
Water contains carbon dioxide, and a slightly acidic pH is normal.
A water production rate of around 30 tons per hour
Concentrated water is not very useful; how do you recycle and use it?
It’s normal for the product to be slightly acidic. The poster mentioned that for primary softening, a cation exchange bed is used; the water coming out of such a bed has a higher acidity, as some of the cations are replaced by hydrogen ions, making the water acidic. During the RO process, it is normal for the produced water to be acidic if the removal rate of anions is not high enough. It is recommended to add a stage of degassing after the cation resin bed, as carbon dioxide tends to be removed easily under acidic conditions. If pure water is desired, it is recommended to add an anion resin bed or a mixed resin bed after the RO system.