The cleaning of water refers to the process of removing pollutants from water before it enters a body of water or is reused. Sewage treatment refers to the process of treating wastewater. There are numerous sewage management methods, with each sewage treatment method consisting of several steps. In most homes, one set of pipes transports clean water while the other transports used water. Sewers are the network of pipes used for sewage treatment. It is essentially a transportation system that transports sewage from the point of production to the point of disposal or treatment through the drainage systems.
Download PDF of Class 7 Chemistry Worksheet on Chapter 18 Wastewater Story – Set 1
CBSE Class 7 Chemistry Worksheet Chapter 18 Wastewater Story – Set 1
Q1. Chlorine tablets are used to remove __ from wastewater.
a.) Odour
b.) Bacteria
c.) Dissolved impurities
d.) All of the above
Q2. Sewage contains ___ impurities.
a.) Organic
b.) Inorganic
c.) Nutrients
d.) All of the above
Q3. Solid wastes are commonly called ___.
a.) Sewage
b.) Drainage
c.) Garbage
d.) All of the above
Q4. Sewage can be used to produce ___.
a.) Biogas
b.) Manure
c.) Fertilisers
d.) All of the above
Q5. Which of the following organisms is used in a vermicomposting toilet?
a.) Earthworm
b.) Flatworm
c.) Roundworm
d.) All of the above
Q6. Fill in the blanks.
a.) The activated sludge is ___ % water.
b.) A solid which can be extracted in a sewage plant is ___.
c.) ____ can be decomposed in an aerated tank.
Q7. State True or False.
a.) The smell and sight of open drains are pleasant.
b.) One should not defecate in the open.
c.) Water should be treated before discharging it into the sea, rivers or other water bodies.
Q8. How can the sludge be disposed of?
Q9. Define sewers and manholes.
Q10. Comment on the statement, “Natural water is the purest form of water.”
Q11. What do you understand by the term biogas?
Q12. How do a bar screen and a grit and sand removal tank help with water cleaning?
Q13. What are the various components of sewage?
Q14. What is a septic tank?
Q15. What are the ill effects of open drains?
Q16. How can we help in maintaining sanitation in public places?
Q17. Why should oils and fats not be released into the drain? Explain.
Q18. How does a septic tank function?
Q19. Why is a wastewater treatment plant important?
Q20. Describe various steps of cleaning wastewater in a wastewater treatment plant.
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