The stages when treating water to make it safe to drink : Chlorination is done .
Explanation:
Why do we need to do these stages?
1. Sedimentation :
In the first step coagulation is done by adding alums or salts of Aluminium Sulfates .when this is done , The impurities becomes heavy because they grow into large particles called floc and settle down at the bottom,.
This process of settlement of particles at the bottom is called sedimentation.
Here only dissolved organic impurities gat settle down. The light weight pathogen are still present in the sample. At this stage water is not suitable for drinking.
2. Filtration : This include passing of water through a porous membrane . This helps in removal of suspended particulate matter present in the water.Sand also get separated from water at this stage.
At this stage also water is not safe for drinking because it still contain viruses which can pass through the pores
3. Chlorination:
This is the process of adding chlorine to the water. Chlorine is good disinfectant and effective against killing bacteria and viruses present in the water. Chlorine is cheap and inexpensive. It inactivate the microorganisms by weakening their cell membrane.
It oxidize other impurities also because of its oxidising nature:
Cl2 + water release reactive Oxygen which kill other harmful germs.
Now water can be useful for drinking
