Science

Wastewater Story

Question:

What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas.

Answer:

Sewage is a liquid containing wastes which is disposed by households, industrial and agricultural activities in water. It is harmful to discharge untreated sewage into rivers or seas because it can pollute the whole sources of water. Sewage contains harmful substances and disease causing organisms. It is therefore dangerous to release untreated sewage in water.

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Wastewater Story

Q 1.

Outline your role as an active citizen in relation to sanitation.

Q 2.

Why should oils and fats be not released in the drain? Explain.

Q 3.

Explain the relationship between sanitation and disease.

Q 4.

Name two chemicals used to disinfect water.

Q 5.

What is sewage? Explain why it is harmful to discharge untreated sewage into rivers or seas.

Q 6.

Fill in the blanks:
(a) Cleaning of water is process of removing __________
(b) Wastewater released by houses is called __________.
(c) Dried __________ is used as manure.
(d) Drains get blocked by __________ and __________.

Q 7.

What is sludge? Explain how it is treated.

Q 8.

Describe the steps involved in getting clarified water from wastewater.

Q 9.

Explain the Junction of bar screens in a wastewater treatment plant.

Q 10.

Untreated human excreta is a health hazard. Explain.

Q 11.

Why should oils and fats be not released in the drain? Explain.

Q 12.

Here is a crossword puzzle. Good luck!
ncert-solutions-class-7-science-chapter-18-wastewater-story-01
Across:
3. Liquid waste products
4. Solid waste extracted in sewage treatment
6. A word related to hygiene
8. Waste matter discharged from human body
Down:
1. Used water
2. A pipe carrying sewage
5. Micro-organisms which cause cholera
7. A chemical to disinfect water