Answer:
The stages when treating water to make it safe to drink :<u> Chlorination </u>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 <u><em>sedimentation.</em></u>
<u><em>Here only dissolved organic impurities gat settle down. The light weight pathogen are still present in the sample. </em></u><em>At this stage water is not suitable for drinking.</em>
2. Filtration : This include passing of water through a porous membrane . This helps in <u>removal of suspended particulate matter present in the wate</u>r.Sand also get separated from water at this stage.
At this stage also water is not safe for drinking because it still contain <u>viruses </u>which can pass through the pores
3. Chlorination:
This is the process of adding chlorine to the water. Chlorine is good disinfectant and <u>effective against killing bacteria and viruses present in the water.</u> 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