Exercises
1. Fill in the blanks:
(a) Cleaning of water is a process of removing
(b) Wastewater released by houses is called
(c) Dried
is used as manure.
(d) Drains get blocked by
and
2. What is sewage? Explain why it is harmful to discharge untrea
sewage into rivers or seas.
3. Why should oils and fats be not released in the drain? Explain.
4. Describe the steps involved in getting clarified water from wastewa
5. What is sludge? Explain how it is treated.
Answers
Answer:
1) POLLUTANT
2) SEWAGE
3) SLUDGE
4) OILS AND FATS
2) Ans: sewage is a liquid waste which has water as it's largest component along with various types of impurities like waste water from houses, offices and factories ets.
Discharging untreated sewage into rivers and waters can cause water pollution.
3) Ans: Oils and fats can clog the drains reducing its effectiveness in filtering water. In open drains, they block the pores in the soil and thus hamper the filtration by soil. Hence oils and fats cannot be released into drains.
4) Ans:
1) wastewater is passed through bar screens which remove large objects like days, sticks, cans, plastic packets, napkins etc.
2) water then goes through Grit and Sand removal tank, where sand, grit and pebbles settle down.
3) water is then allowed to settle in atank where solids like faeces settle at the bottom and are removed with a scraper.
5) Ans: Sludge is a human waste in waste water left during sewage treatment. Since it is organic waste, it is used to produce bio gas manure
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Answer:
pollution
sewage
sludge
oil and fats