Science

Wastewater Story

Question:

Describe the steps involved in getting clarified water from wastewater.

Answer:

Following steps are involved in the purification of water:
(i) Firstly all the physical impurities like stones, plastic bags, cans etc. are to be removed. It is done by passing the water through bar screens.
(ii) Then water is taken to grit and sand removal tank where impurities are removed by sedimentation.
(iii) Solid impurities and feaces etc. are collected from bottom of water. These impurities collected are called sludge.
(iv) Clarified water is cleaned of other impurities by aerator. All disease causing bacteria are removed by chlorination.

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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