Multiple Choice Questions.....................
Question 1: Which of the following is wastewater?
(a) Water trickling from a damaged tap.
(b) Water coming out of a shower.
(c) Water flowing in a river.
(d) Water coming out of laundry.
Solution 1: (d) Water coming out of laundry.
After routine, water discharged during operations such as washing clothes, flushing toilets, cleaning utensils renders the water dirty. That water is known as waste water. Water coming out of the broken tap, water coming out of the shower and water flowing through a river is not dirty, so the correct response is water coming out of a laundry.
Question 2: Sewage is mainly a
(a) liquid waste.
(b) solid waste.
(c) gaseous waste.
(d) mixture of solid and gas.
Solution 2: (a) liquid waste.
The waste water that comprises domestic and industrial liquid waste is sewage water. It includes different suspended solids and microorganisms that are harmful.
Question 3: Which of the following is/are products of wastewater treatment?
(a) Biogas
(b) Sludge
(c) Both biogas and sludge
(d) Aerator
Solution 3: (c) Both biogas and sludge
Treatment water is permitted to settle in a wide tank that is sloped towards the middle during waste water. At the bottom, solids such as faeces accumulate and are collected with a scraper. That's the sludge here. The floatable solids, including oil and grease, are collected by a skimmer. Such cleared water is called clarified water. The sludge is transported by the anaerobic bacteria to a separate tank where it is decomposed. In the process, the biogas generated can be used as fuel or can be used to generate electricity.
Question 4: An open-drain system is a breeding place for which of the following.
(a) Flies
(b) Mosquitoes
(c) Organisms which cause diseases
(d) All of these
Solution 4: (d) All of these
The opening drainage mechanism allows the foul smell to be troublesome. The breeding source for mosquitoes and flies is the open drainage system. The open system of drainage also allows the growth of species that cause disease.
Question 5: Water polluted by various human activities causes a number of water-borne diseases. Which of the following is not a waterborne disease?
(a) Cholera
(b) Typhoid
(c) Asthma
(d) Dysentry
Solution 5: (c) Asthma
Asthma is an infectious infection, while infected water and food spreads cholera, typhoid and dysentery.
Question 6: Pick from the following one chemical used to disinfect water.
(a) Chlorine
(b) Washing soda
(c) Silica
(d) Coal
Solution 6: (a) Chlorine
Chorine is used to destroy harmful species, and chlorination is known as the method of adding chlorine.
Question 7: The system of a network of pipes used for taking away wastewater from homes or public buildings to the treatment plant is known as
(a) sewers
(b) sewerage
(c) transport system
(d) treatment plant
Solution 7: (b) sewerage
The system of a network of pipes used for taking away wastewater from homes or public buildings to the treatment plant is known as sewerage.
Question 8: Which of the following is a part of inorganic impurities of the sewage?
(a) Pesticides
(b) Urea
(c) Phosphates
(d) Vegetable waste
Solution 8: (c) Phosphates
Organic waste that serves as impurities in sewage water is eaten by pesticides, urea and vegetable waste, while phosphates are the inorganic impurities found in sewage.
Question 9: In a filtration, plant water is filtered using layers of
(a) sand and clay.
(b) clay and fine gravel.
(c) sand and fine gravel.
(d) sand, fine gravel and medium gravel.
Solution 9: (d) sand, fine gravel and medium gravel.
Wastewater is permitted to join a grid of sand, fine gravel and medium gravel during wastewater treatment. The pace of waste water is slowed down here to allow the settlement of sand, fine gravel and medium gravel.
Question 10: Which of the following is not a source of wastewater?
(a) Sewers
(b) Homes
(c) Industries
(d) Hospitals
Solution 10: (a) Sewers
Sewers are a network of large and small pipes that bring waste, i.e. treatment plants, from the point of processing to the point of disposal.
Very Short Answer Questions....................
Question 11: Why are open drains a concern?
Solution 11: Open drains are a problem because they contain unhygienic and unsafe conditions that contribute to the spread of disease.
Question 12: State whether the following statements are True or False. In case a statement is false, write the correct statement.
(a) Sewage is a solid waste which causes water pollution and soil pollution.
(b) Used water is wastewater.
(c) Wastewater could be reused.
(d) Where underground sewerage systems and refuse disposal systems are not available, the high-cost on-site sanitation system can be adopted.
Solution 12:
a) False- Sewage is a liquid waste that is responsible for water and soil contamination.
b) True
c) True
d) False- The low-cost on-site sanitation system can be adopted where underground sewerage systems and refuse disposal systems are not usable.
Question 13: How are open drains harmful to human health?
Solution 13: The opening drainage mechanism allows the foul smell to be troublesome. The breeding source for mosquitoes and flies is an open drainage system. The open system of drainage also allows the growth of species that cause disease. Therefore, drains are detrimental to human health.
Short Answer Questions.............
Question 14: Name two inorganic impurities present in sewage.
Solution 14: Two inorganic impurities present in sewage are Nitrates, Phosphates.
Question 15: Animal waste, oil and urea are some of the organic impurities present in sewage. Name two more organic impurities present in sewage.
Solution 15: Organic impurities present in sewage are Fruits and Vegetables.
Question 16: Name two alternative arrangements for sewage disposal where there is no sewerage system.
Solution 16:
Two alternative arrangements for sewage disposal where there is no sewerage system are:
(i) Septic tanks
(ii) Composting pits
Question 17: A man travelling in a train threw an empty packet of food on the platform. Do you think this is a proper waste disposal method? Elaborate.
Solution 17: No, what a man does is not a form of proper disposal. The waste must always be stored or brought in a nearby dustbin before a suitable place for the food packet to be disposed of is found.
Question 18: Why should we not throw
(a) used tea leaves into the sink?
(b) cooking oil and fats down the drain?
Solution 18:
a) Used tea leaves may create a blockage in the sink.
b) It hardens cooking oil and fats and blocks the sink.
Question 19: Match the items of Column I with the items of Column II with reference to sewage.
Solution 19:
Question 20: Given below is a jumbled sequence of the processes involved in a wastewater treatment plant. Arrange them in their correct sequence.
(a) Sludge is scraped out and skimmer removes the floating grease.
(b) Water is made to settle in a large tank with a slope in the middle.
(c) Large objects like plastic bags are removed by passing wastewater through bar screens.
(d) Sand, grit and pebbles are made to settle by decreasing the speed of incoming wastewater.
(e) Wastewater enters a grit and sand removal tank.
Solution 20:
(c) Large objects like plastic bags are removed by passing wastewater through bar screens.
(e) Wastewater enters a grit and sand removal tank.
(d) Sand, grit and pebbles are made to settle by decreasing the speed of incoming wastewater.
(b) Water is made to settle in a large tank with a slope in the middle.
(a) Sludge is scraped out and skimmer removes the floating grease.
Question 21: Three statements are provided here which define the terms –
(a) sludge
(b) sewage and
(c) wastewater.
Pick out the correct definition for each of these terms.
(a) The settled solids that are removed in wastewater treatment with a scraper.
(b) Water from the kitchen used for washing dishes.
(c) Wastewater released from homes, industries, hospitals and other public buildings.
Solution 21:
(a) The settled solids that are removed in wastewater treatment with a scraper: Sludge
(b) Water from the kitchen used for washing dishes: Wastewater
(c) Wastewater released from homes, industries, hospitals and other public buildings: Sewage
Question 22: A mixture (x) in water contains suspended solids, organic impurities, inorganic impurities (a), nutrients (b), disease-causing bacteria and other microbes. Give names for (x), (a) and (b)?
Solution 22:
(x) Sewage
(a) Nitrates and phosphates
(b) Phosphorus and nitrogen
Long Answer Questions.................
Question 23: What are the different types of inorganic and organic impurities generally present in sewage?
Solution 23:
(i) Inorganic impurities present in sewage– Nitrates, Phosphates and Metals.
(ii) Organic impurities present in sewage– Fruit and Vegetable wastes, oil, urea, human faeces, animal waste, pesticides and herbicides.
Question 24: The terms sewage, sewers and sewerage are interlinked with each other. Can you explain, how?
Solution 24: As sewage is a mixture of waste water coming from households and other areas. Sewers are pipes carrying sewage and a network of sewage carrying pipes is sewerage.
Question 25: Fill in the blanks in the following statements using words given in the box.
A very _________ number of our people defecate in the open. It may cause _________ pollution and soil pollution. Both the surface water and _________ water get polluted. _________ water is the source for wells, tube-wells and _________. Thus it becomes the most common route for _________ borne diseases like _________, dysentery, etc.
Solution 25:
A very large number of our people defecate in the open. It may cause water pollution and soil pollution. Both the surface water and ground water get polluted. Ground water is the source for wells, tube-wells and hand-pumps. Thus it becomes the most common route for water borne diseases like cholera, dysentery, etc.
Question 26: Describe various steps of cleaning wastewater in a wastewater treatment plant.
Solution 26: Wastewater treatment requires physical, chemical and biological processes that remove wastewater-contaminating physical, chemical and biological matter.
- Via bar displays, waste water is passed through. Large items are eliminated, such as rags, sticks, cans, plastic bags, napkins.
- 2. Then water goes to a removal tank for grit and sand. In order to allow sand, grit and pebbles to settle down, the velocity of the incoming waste water is reduced.
- In a wide tank which is sloped towards the centre, the water is then allowed to settle. At the bottom, solids such as faeces accumulate and are collected with a scraper. That's the sludge here. The floatable solids, including oil and grease, are collected by a skimmer. Such cleared water is called clarified water. The sludge is transported by the anaerobic bacteria to a separate tank where it is decomposed. In the process, the biogas generated can be used as fuel or can be used to generate electricity.
- To allow aerobic bacteria to expand, air is injected into the clarified water. Human waste, animal waste, soaps and other unnecessary matter are ingested by bacteria left in clarified water.
The suspended microbes settle at the bottom of the tank as activated sludge after several hours. From the top, the water is then removed. The sludge that is triggered is around 97 percent water. Via sand drying beds or machines, the water is removed. As compost, dried sludge is used, returning organic matter and nutrients to the soil.
A very low amount of organic material and suspended matter is in the treated water. It is released into the sea, into the river, or into the land. Nature further cleans it up. Often, before releasing it into the delivery system, it may be important to disinfect water with chemicals like chlorine and ozone.
Question 27: Think and suggest some ways to minimise waste and pollutants at their source, taking your home as an example.
Solution 27:
(i) Do not throw into the drain used tea leaves, solid food scraps, etc. Throw waste in the dustbin.
(ii) Chemicals should not be dumped into the sewer, such as drugs, paints, insecticides, etc., as they raise the sewage contamination load.