Tuesday , July 5 2022

NCERT 7th Class (CBSE) Science: Wastewater Management

Question: What is sludge? Explain how it is treated.

Answer: Solids waste like faeces settle at the bottom of tank during sedimentation is called sludge.

Sludge is removed with a scraper and then transferred to a separate tank where it is decomposed by the anaerobic bacteria to produce biogas.

Question: Untreated human excreta is a health hazard. Explain.

Answer: Untreated human excreta is a health hazard as it can cause water pollution and soil pollution. Both the surface water and ground water gets polluted. Thus, it becomes the most common route for water borne diseases which include cholera, typhoid, polio, meningitis, hepatitis and dysentery. It is also a big threat to sanitation.

Question: Name two chemicals used to disinfect water.

Answer: Two chemicals used to disinfect water are chlorine and ozone.

Question: Explain the function of bar screens in a wastewater treatment plant.

Answer: Bar screen in a waste water treatment plant is used to remove the large objects like rags, sticks, cans, plastic packets and napkins.

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

Answer: Role as an active citizen in relation to sanitation:

  1. Contribute in maintaining sanitation at public places and should not scatter litter anywhere.
  2. Throwing garbage or waste at its desired place.
  3. Ensure that my surrounding and neighbourhood is clean and help the municipality in maintaining proper sanity.
  4. Preventing clogging of drains by not releasing oil and fat and solid waste into the drain.
  5. Immediately inform the municipality about any sewage leakage and for the maintenance of dustbins.

Question: Explain the relationship between sanitation and disease.

Answer: Poor sanitation and contaminated drinking water is the cause of large number of diseases. Poor sanitation leads to:

  1. Growth of harmful microbes, flies and mosquitoes. Hence spread of many diseases like cholera, typhoid, polio, meningitis, hepatitis and dysentery.
  2. Pollution of soil and water.

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