TOPIC: WASTE WATER STORY
Q.1.What is sewage?
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Q.2. Name some contaminants found in sewage.
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Q.3.Give reasons.
a) Oil and fats such as cooking oils, solid food remains, plastic bags, toys etc. should never be thrown in a drain.
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b) Chemicals such as paints, medicines, insecticides should not be thrown into drains.
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c) During the treatment of waste water, air is pumped into it.
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d) Untreated human excreta is a health hazard.
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Q.4. List the four steps involved in waste water treatment.
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Q.5.What do you understand by the term sewerage?
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Q.6.What is the use of manholes provided in the sewerage?
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Q.7.What is the use of skimmer in a waste-water treatment plant?
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Q.8. How is sludge decomposed in a waste-water treatment plant?
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Q.9. Name any two chemicals used to disinfect water.
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Q.10. Name any four onsite sewage disposal systems suitable for rural areas.
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Please click on below link to download CBSE Class 7 Science Waste water Set B
