Demineralization is the process of removing mineral salts from water by using the ion exchange process.

 
Demineralised water is water completely free (or almost) of dissolved minerals as a result of one of the following processes :
   
• Distillation
• Deionization
• Membrane filtration (reverse osmosis or nanofiltration)
• Electrodyalisis
• Or other technologies.

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The water free from any mineral is called De- Mineralised Water (D.M.Water). Naturally occurring water has various salts in dilute form which are called dissolved solids (TDS) . When the water having such mineral is required to be free from this, it is to be treated in Ion Exchange Resins column (H form) which adsorbs the positively charge ion. Now the cations free passed through Anion Resin Column (OH form) which adsorbs the negatively charged anions and water free from the total ions shall comes out from the system.
 

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