Question

Very short answer type questions:
18.
Name the three infectious diseases caused by stagnant sewage.
19.
Name any two organic impurities present in sewage.

20.
Name the various wastes which should not be thrown down the drain.

Name the three stages of sewage treatment.​

Answer 1

18. Three diseases caused by stagnant sewage are giardiasis, dwarf tapeworm infection and threadworm infection.

19. The two organic impurities present in sewage water are human faeces and animal wastes like animal dung.

20. 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 reducing its effectiveness in filtering water.

The three stages of sewage treatment :-

There are three main stages of the wastewater treatment process, aptly known as primary, secondary and tertiary water treatment. In some applications, more advanced treatment is required, known as quaternary water treatment

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