What is demineralization of water?

Water stuffed with mineral ions is unsafe for drinking. Demineralization of water refers to the process of relieving the water from these mineral ions so that it becomes safe for our consumption. Demineralized water is also known as Demin water or Deionised water. This demineralization or deionization process is generally performed through a demineralization plant.

Mineral ions in impure water

The different mineral ions present in water can be divided into cations and anions.

- Cations: Magnesium, Calcium, Potassium and Sodium

- Anions: Chloride, Nitrate and Bicarbonate

Types of deionization:

As mentioned earlier, the demineralization plants use deionization system to purify the drinking water. There are 2 major types of the deionization process-

1. Two-bed deionization

A 2-bed deionizer comes with 2 vessels- one contains cation-exchange ion resin in H+ form & the other comes with anion-exchange resin in OH- form. When water is flown through cation column, all cations would be exchanged for the hydrogen ions. It’s to note here that to keep water balanced electrically, for each monovalent cation, 1 hydrogen ion would be exchanged & for each divalent cation, 2 hydrogen ions would be exchanged. Same rings true with anion exchange. Decationised ater is flown through anion column where all negatively-charged ions would be exchanged for the hydrogen ions that further combine with hydrogen ions, leading to formation of H20 or water.

2. Mixed-bed deionization

Here you will have the cation & anion-exchanged resins mixed intimately & contained in single- pressure vessel. This thorough mix of cation-exchangers & anion-exchangers in one column makes mixed-bed deionizer somewhat equivalent to long series of 2-bed plants. This way, water obtained from mixed-bed is generally higher compared to a 2-bed plant.

How does a demineralization system work?

Impure water collected at a demineralization plant is initially passed through couple of polystyrene beds stuffed with ion-exchanged resins. In the 1 st bed, the cation-exchange resins would work to release H+ (Hydrogen) ions or some other positive ions in place of impured cations in the unsafe water. On the other hand, in the 2 nd bed, the anion-exchange resin would release OH- (hydroxyl) ions or some other negative ions in place of impured anions in the unsafe water. Here is a step by step brief on the process.

- Feed water would be pumped to Multi-media filters & activated carbon filters.
- The units would remove the cationic ions.
- Next, the water would enter through Strong-Base Anions & anions are removed from water stream.
- The mixed-bed units would then polish up the water & reduce its conductivity level.
- Feed pumps release regenerated water to regeneration skids.
- Various regeneration skids extend the necessary dilute chemical right to demineralization
vessels.
- Now, finally, this demineralized water would be passed to demineralization plant's storage tank.

Various applications:

- Laboratories - Hospitals
- Pharmaceuticals
- Electroplating
- Boilers feed water
- Ion-exchange plants

Kelvin Water Technologies is one of the leading names when it comes to demineralization plants manufacturing and maintenance in India. Our group of demineralization specialists and experienced engineers assure efficient and robust demineralization plants.