Case Study Questions Class 7 Science Chapter 18 Wastewater Story
CBSE Class 7 Case Study Questions Science Wastewater Story. Important Case Study Questions for Class 7 Board Exam Students. Here we have arranged some Important Case Base Questions for students who are searching for Paragraph Based Questions Wastewater Story.
At Case Study Questions there will given a Paragraph. In where some Important Questions will made on that respective Case Based Study. There will various types of marks will given 1 marks, 2 marks, 3 marks, 4 marks.
CBSE Case Study Questions Class 7 Science Wastewater Story
Case study 1
All of us use water in our homes and make it dirty. Rich in lather, mixed with oil, black–brown water that goes down the drains from sinks, showers, toilets, laundries is dirty. It is called wastewater. This used water should not be wasted. We must clean it up by removing pollutants. Clean water that is fit for use is unfortunately not available to all. It has been reported that more than one billion of people have no access to safe drinking water. This accounts for a large number of water-related diseases and even deaths. People even children walk for several kilometers to collect clean water.
The increasing scarcity of freshwater is due to population growth, pollution, industrial development, mismanagement and other factors. Realizing the urgency of the situation on the World Water Day, on 22 March 2005, the General Assembly of the United Nations proclaimed the period 2005–2015 as the International Decade for action on “Water for life”. All efforts made during this decade aim to reduce by half the number of people who donot have access to safe drinking water.
Que. 1) Which of the following is waste water?
(a) Dirty water
(b) Fresh water
(c) Good water
(d) Bad water
Que. 2) The increased scarcity of water is due to which of the following reasons?
(a) Population growth
(b) Less population
(c) More peoples
(d) Overexploitation
Que. 3) …………………………………………………………………..………billion of people have no excess to safe drinking water.
(a) One
(b) Two
(c) five
(d) Ten
Que. 4) Who walks several kilometers to collect clean water?
Que. 5) What causes water related disease and even death?
Answer Key
Que. 1)(a) Dirty water
Que. 2) (a) Population growth
Que. 3) (a) One
Que. 4) Answer: Peoples and children walks several kilometers to collect clean water.
Que. 5) Answer: Drinking unsafe and unhygienic water can cause water related disease and even death.
Case study 2
Sewage is wastewater released by homes, industries, hospitals, offices and other users. It also includes rainwater that has run down the street during a storm or heavy rain. The water that washes off roads and rooftops carries harmful substances with it. Sewage is a liquid waste. Most of it is water, which has dissolved and suspended impurities. In a home or a public building generally one set of pipes brings clean water and another set of pipes takes away wastewater. Imagine that we could see through the ground. We would see a network of big and small pipes, called sewers, forming the sewerage. It is like a transport system that carries sewage from the point of being produced to the point of disposal, i.e. treatment plant.
Manholes are located at every 50 m to 60 m in the sewerage, at the junction of two or more sewers and at points where there is a change in direction.
Que. 1) Manholes are located at how much distance in the sewerage?
(a) 50 to 60m
(b) 60 to 50m
(c) 50m
(d) 100m
Que. 2) Sewage is waste water released by which of the following?
(a) Homes
(b) Industries
(c) Offices
(d) All
Que. 3) Where does the sewers transports the sewage after collecting all the wastewater from various sources?
(a) Treatment plant
(b) Plant
(c) Reservoir
(d) None
Que. 4) Define sewers.
Que. 5) Rain water that runs down in the streets during heavy rainfall is also waste water is it true or false.
Answer Key
Que. 1)(a) 50 to 60m
Que. 2) (d) All
Que. 3) (a) Treatment plant
Que. 4) Answer: The network of small pipes and big pipes which transports the sewage to treatment plant is called as sewers.
Que. 5) Answer: The statement that rain water runs down in the street is also a waste water is true.
Case study 3
Treatment of wastewater involves physical, chemical, and biological processes, which remove physical, chemical and biological matter that contaminates the wastewater.
1.) Wastewater is passed through barscreens. Large objects like rags,sticks, cans, plastic packets, napkinsare removed
2.) Water then goes to a grit and sandremoval tank. The speed of theincoming wastewater is decreased toallow sand, grit and pebbles to settle down.
3.) The water is then allowed to settle ina large tank which is sloped towards
the middle. Solids like faeces settleat the bottom and are removed with a scraper. This is the sludge. Askimmer removes the floatable solidslike oil and grease. Water so clearedis called clarified water The sludge is transferred to aseparate tank where it is decomposedby the anaerobic bacteria. The biogas
Produced in the process can be used as fuel or can be used to produce electricity.
4.) Air is pumped into the clarified waterto help aerobic bacteria to grow.Bacteria consume human waste, foodwaste, soaps and other unwantedmatter still remaining in clarifiedwater.
After several hours, the suspendedmicrobes settle at the bottom of the tank
As activated sludge. The water is thenremoved from the top.The activated sludge is about 97%water. The water is removed by sanddrying beds or machines. Dried sludgeis used as manure, returning organicmatter and nutrients to the soil.The treated water has a very low levelof organic material and suspendedmatter. It is discharged into a sea, a riveror into the ground. Nature cleans it upfurther. Sometimes it may be necessaryto disinfect water with chemicals likechlorine and ozone before releasing itinto the distribution system.
Que. 1) Treatment of waste water involves which of the following process?
(a) Physical
(b) Chemical
(c) Biological
(d) All
Que. 2) Water is disinfected by ……….…………………………..……………………………………………….…..chemical.
(a) Chlorine
(b) Carbon
(c) Oxygen
(d) No chemical
Que. 3) What is the percentage of activated sludge in the waste water treatment?
(a) 95%
(b) 97%
(c) 100%
(d) 0%
Que. 4) Why air is pumped into the clarified water?
Que. 5) What does the treated water have?
Answer Key
Que. 1)(d) All
Que. 2) (a) Chlorine
Que. 3) (b) 97%
Que. 4) Answer: Air is pumped into the clarified water because it helps in the growth of bacteria.
Que. 5) Answer: The treated water have very low level of suspended matter and organic matters.
Case study 4
Waste generation is a natural part ofhuman activity. But we can limit the type of waste and quantity of wasteproduced. Often we have been repelledby offensive smell. The sight of opendrains is disgusting. The situationworsens in the rainy season when thedrains start overflowing. We have towade through the mud pools on the roads. Most unhygienic and unsanitaryconditions prevail. Flies, mosquitoes andother insects breed in it.
You can be an enlightened citizenand approach the municipality or thegram panchayat. Insist that the opendrains be covered. If the sewage ofany particular house makes theneighborhood dirty, you should request them to be more considerateabout others’ health. It has been suggested that we shouldplant eucalyptus trees all alongsewage ponds. These trees absorb allsurplus wastewater rapidly andrelease pure water vapour into theatmosphere.
Que. 1) Waste generation is a……………………………………………………………………………………….. part of day to human activity.
(a) Natural
(b) Artificial
(c) Anthropogenic
(d) Man made
Que. 2) The site of open drains is which of the following?
(a) Ravishing
(b) Good
(c) Disgusting
(d) Excellent
Que. 3) Which tree should be planted along the sewage ponds?
(a) Pine
(b) Eucalyptus
(c) Wild
(d) Sal
Que. 4) What happens to the drains during rainy season?
Que. 5) An open stagnant water source is a breeding ground for whom?
Answer Key
Que. 1)(a) Natural
Que. 2) (c) Disgusting
Que. 3) (b) Eucalyptus
Que. 4) Answer: The drains get overflowed during the rainy seasons
Que. 5) Answer: An open stagnant water source is a breeding ground for mosquitoes, flies and insects.
Case study 5
One of the ways to minimised or eliminatewaste and pollutants at their source isto see what you are releasing down thedrain.Cooking oil and fats should not bethrown down the drain. They canharden and block the pipes. In anopen drain the fats clog the soil poresreducing its effectiveness in filteringwater. Throw oil and fats in the dustbin.
Chemicals like paints, solvents,insecticides, motor oil, medicinesmay kill microbes that help purifywater. So do not throw them downthe drain.Used tealeaves, solid food remains,soft toys, cotton, sanitary towels, etc.Should also be thrown in the dustbin. These wastes choke thedrains. They do not allow free flow of oxygen. This hampers thedegradation process.
In the year 2016, the Government of India has initiated a new mission known as“Swachh Bharat” under which a lot of drives such as proper sewage disposaland providing toilets for everyone have been started. A design of a toilet in which humans excreta is treated by earthworms has beentested in India. It has been found to be a novel, low water-use toilet for safeprocessing of human waste. The operation of the toilet is very simple and hygienic.The human excreta is completely converted to vermi cakes — a resource muchneeded for soil.
Que. 1) In which year government of India initiated “Swachh Bharat”?
(a) 2015
(b) 2018
(c) 2020
(d) 2016
Que. 2) ……………………………………………………………………………….….resource is much needed for soil to be more fertile and good for better yield
(a) Vermi cakes
(b) Soil cakes
(c) Dung cakes
(d) All
Que. 3) Chemical oil and fat should be thrown in drain is it true or false.
(a) True
(b) False
Que. 4) Which design of toilet has been tested in India?
Que. 5) Which waste chokes the drain?
Answer Key
Que. 1)(d) 2016
Que. 2) (a) Vermi cakes
Que. 3) (b) False
Que. 4) Answer: A toilet in which human excreta is treated with the help of earthworms has been tested in India.
Que. 5) Answer: Wastes like solid food waste, soft toys, cotton etc chokes the drain.