Class 7 Waste Water Management
Waste Water Management
KEYWORDS
Sewage: Wastewater which is carried away in the sewer.
Sewer: An underground water pipe which carries away dirty waste water.
Manhole: It is a covered vertical hole in the ground above the underground sewer pipeline.
Sludge: Solid matter produced by sewage treatment.
Contaminant: Dissolved and suspended impurities in sewage.
POINTS TO REMEMBER
• Water is a precious resource. It should not be contaminated, polluted and wasted.
• Wastewaters are of two types: domestic wastewater and industrial wastewater.
• Sewage is the wastewater which is carried away in sewers.
• Drainage carries municipal sewage and dirty waste outside the city.
• Sewage is a liquid waste and it has dissolved and suspended impurities.
• Water pollution is caused by the uncontrolled dumping of excreta, blood, organic debris, soaps, detergents, paper and cloth.
• The sewer system has a system of underground pipes, pumps, and sewage treatment plants that collect untreated liquid sewage.
• An underground water pipe which carries away dirty wastewater is called a sewer.
• Sewage treatment is the process of removing pollutants or contaminants from the sewage water to make it harmless, so that it may be disposed of safely in the water bodies.
Exercises on Waste Water Management
Multiple Choice Questions (MCQs)
1. The organic impurities present in sewage water include –
(a) bacteria
(b) phosphorus
(c) human faeces
(d) nitrates
2. Which of the following is not an inorganic impurity present in sewage?
(a) nitrate
(b) phosphate
(c) urea
(d) metal salt
3. Which of the following organisms produce biogas from sludge in the digester tank of a wastewater treatment
plant?
(a) anaerobic plant
(b) fungi
(c) aerobic bacteria
(d) protozoa
4. Which of the following is not a waterborne disease?
(a) cholera
(b) tuberculosis
(c) typhoid
(d) dysentery
5. Adopting good ……………… practices should be a way of our life
(a) eating
(b) sanitation
(c) reading
(d) none
Answers:
1. (c) 2. (c) 3. (c) 4. (b) 5. (b)
Fill in the blanks:
(a) Wastewater released by houses is called———-.
(b) Cleaning of water is a process of removing——–.
(c) Dried————- is used as a manure.
(d) Drains get blocked by——— and——–.
(e) All the portable toilets are———–.
Answers:
(a) Wastewater released by houses is called Sewage.
(b) Cleaning of water is a process of removing pollutants.
(c) Dried sludge is used as a manure.
(d) Drains get blocked by cooking oil and fats.
(e) All the portable toilets are a chemical toilet.
Very Short Answer Type Questions.
1. Name two organic and inorganic impurities present in sewage.
2. Write the full form of WWTP.
3. Mention one uses that the sludge from sewage treatment can be put to use.
4. What is the cause of a large number of diseases in our country?
5. What type of sewage disposal system will be suited for an isolated cluster of 4 or 5 houses in an area where there is
no sewerage?
Answers:
1. The two organic impurities present in sewage water are human faeces and animal wastes like animal dung. The two inorganic impurities present in sewage water are nitrates and phosphorus.
2. Waste Water Treatment Plant
3. Sludge is added back to the aeration tank to increase the population of aerobic bacteria.
4. The cause of a large number of diseases in our country is improper Sanitation habits.
5. Septic tank toilets are suitable for those places where there is no sewage system. A cluster of four or five houses can also install and maintain a common septic tank. A septic tank works for a fairly long time after which it has to be cleaned.