Yukhaimi, chemical technician explained the process of demineralization to me.
Firstly, service water is fed to the carbon filter. The influent water is passed through a column of activated carbon to remove the major part of the organic matter and residual chlorine.
Then, the water is routed to the cation exchanger packed with a column of strong acid cation, exchange ion resin in the hydrogen form.
The cation effluent is then passed through a strong base anion inside the anion exchanger. The hydrogen ions from the cation resin neutralized the hydroxide ions from the anion resins and yield pure water.
The demineralized water is then passed to the mixed bed exchanger which contain a mixture of anion exchanger and cation exchanger to further polish the water before the water is discharged to demineralized water storage tank.