Question

Explain the various techniques used for water purification in the Water Works System.

Answer 1

There are number of methods commonly used to purify water.
1) Filtration - Filters separate unblocked chlorine, chloride oxide, phenol, pesticides and organic solvents. Activated carbon is used as a filter effectively.
2) Distillation - It is a method which is based on the boiling point. Various impurities get separated due to the difference in boiling point . The vapours of water then condenses after passing through condensor.
3) Coagulation and flocculation - It involves the addition of chemicals to remove particles suspended in water. These particles can be inorganic like clay or organic like virus and bacteria.
4) Sedimentation - In this technique, heavy particles in raw water settle out into holding ponds or basins before filtration.
5) Reverse osmosis - It is most widespread technique used now-a-days. This method is capable of separating impurities and particles which are smaller than nanometre.
6) UV sterlisation - Ultraviolet radiation has a germicidal effect. So used to purify water.
7) Ozonation - This technique oxidise all bacteria, mold , yeast spores, organic material and viruses.