Wastewater Story — Science STD 7 — Question

We must minimise and manage waste at our houses before its disposal in the following manner:
(i)Cooking oil and fats should not be thrown down the drain. They can harden and block the pipes. In an open drain, the fats clog the soil pores and reduce its effectiveness in filtering water. Throw oil and fats in the dustbin.
(ii)Used tea leaves, solid food remains, soft toys, cotton, sanitary towels, etc. should also be thrown in the dustbin. These wastes choke the drains. They do not allow free flow of oxygen and hamper the degradation process.
(iii)Chemicals like paints, solvents, insecticides, medicines and motor oils should not be thrown in drains as they may kill microbes that help to purify water.