Basic Science Solutions for Class 7 Science Chapter 18 Waste Management are provided here with simple step-by-step explanations. These solutions for Waste Management are extremely popular among Class 7 students for Science Waste Management Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Basic Science Book of Class 7 Science Chapter 18 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Basic Science Solutions. All Basic Science Solutions for class Class 7 Science are prepared by experts and are 100% accurate.

Page No 170:

Question A.1:

Answer:

The wastewater from sources such as kitchens, toilets, homes and offices, which is carried away by sewers and drains, is called municipal sewage.

Page No 170:

Question A.2:

The wastewater from sources such as kitchens, toilets, homes and offices, which is carried away by sewers and drains, is called municipal sewage.

Answer:

Black water is the wastewater from toilets carried away by sewers.
The wastewater from kitchens and bathrooms is referred to as grey water.

Page No 170:

Question A.3:

Black water is the wastewater from toilets carried away by sewers.
The wastewater from kitchens and bathrooms is referred to as grey water.

Answer:

The three main sources of liquid waste are the following:
(i) Industrial effluents
(ii) Rainwater carrying waste
(iii) Sewage

Page No 170:

Question A.4:

The three main sources of liquid waste are the following:
(i) Industrial effluents
(ii) Rainwater carrying waste
(iii) Sewage

Answer:

Treating wastewater refers to ridding it of pollutants in treatment plants and reusing the water for domestic and industrial purposes.

Page No 170:

Question A.5:

Treating wastewater refers to ridding it of pollutants in treatment plants and reusing the water for domestic and industrial purposes.

Answer:

The suspended solid waste in water, which settles down in tanks during the primary treatment of wastewater, is known as sludge. It can be used to prepare compost.

Page No 170:

Question A.6:

The suspended solid waste in water, which settles down in tanks during the primary treatment of wastewater, is known as sludge. It can be used to prepare compost.

Answer:

Here are two points to observe to reduce pressure on treatment plants.
(i) We should not flush solid waste down drains.
(ii) We should not throw non-biodegradable waste into open drains.

Page No 170:

Question B.1:

Here are two points to observe to reduce pressure on treatment plants.
(i) We should not flush solid waste down drains.
(ii) We should not throw non-biodegradable waste into open drains.

Answer:

Open drains are meant to carry run-off during monsoons, but these drains are flooded during excessive rain and become breeding grounds for mosquitoes. Besides, these drains are clogged because solid waste is thrown into them, causing water to remain stagnant. This stagnant water provides a perfect habitat for mosquitoes and other flies that spread diseases.

Page No 170:

Question B.2:

Open drains are meant to carry run-off during monsoons, but these drains are flooded during excessive rain and become breeding grounds for mosquitoes. Besides, these drains are clogged because solid waste is thrown into them, causing water to remain stagnant. This stagnant water provides a perfect habitat for mosquitoes and other flies that spread diseases.

Answer:

Everyday, as the human population keeps increasing, the amount of the waste generated also increases. Also, most of the artificially generated substances are non-biodegradable, and natural agents are not capable of assisting in recycling this waste. Therefore, it is important for us to find ways of managing the waste we generate.

Page No 170:

Question B.3:

Everyday, as the human population keeps increasing, the amount of the waste generated also increases. Also, most of the artificially generated substances are non-biodegradable, and natural agents are not capable of assisting in recycling this waste. Therefore, it is important for us to find ways of managing the waste we generate.

Answer:

Primary treatment of wastewater involves the separation of solid materials (rags, leaves, plastic wrappers, paper, etc.) from water using screens or strainers. The water is then passed through settlement tanks, where the suspended solids settle and form a sludge. This sludge is called primary sludge.

Page No 170:

Question B.4:

Primary treatment of wastewater involves the separation of solid materials (rags, leaves, plastic wrappers, paper, etc.) from water using screens or strainers. The water is then passed through settlement tanks, where the suspended solids settle and form a sludge. This sludge is called primary sludge.

Answer:

Organic matter is separated from sewage during secondary treatment, in which aerobic and/or anaerobic bacteria work upon the organic matter present in sewage to settle it at the bottom of aeration tanks. Sometimes, to fasten the activity of aerobic bacteria, air is blown into these tanks.

Page No 170:

Question B.5:

Organic matter is separated from sewage during secondary treatment, in which aerobic and/or anaerobic bacteria work upon the organic matter present in sewage to settle it at the bottom of aeration tanks. Sometimes, to fasten the activity of aerobic bacteria, air is blown into these tanks.

Answer:

Wetlands, i.e., natural or man-made ponds, can be used as a cost-effective natural alternative to sewage treatment plants. A series of ponds can be used to filter water of all the waste that it contains. These ponds have a rich variety of microbes that naturally degrade and settle solid waste. Grass and reeds help in filtering solid waste physically and also take away harmful chemicals from water, thereby cleaning it.

Page No 170:

Question B.6:

Wetlands, i.e., natural or man-made ponds, can be used as a cost-effective natural alternative to sewage treatment plants. A series of ponds can be used to filter water of all the waste that it contains. These ponds have a rich variety of microbes that naturally degrade and settle solid waste. Grass and reeds help in filtering solid waste physically and also take away harmful chemicals from water, thereby cleaning it.

Answer:

The problem of absence of a sewage system in villages can be overcome by setting up a biogas plant. Waste from sanitary toilets can be used as the input for the plant for manufacturing biogas that is rich in methane, an efficient fuel that causes very little pollution. The biogas thus produced can be used for domestic purposes, such as cooking.

Page No 170:

Question C:

The problem of absence of a sewage system in villages can be overcome by setting up a biogas plant. Waste from sanitary toilets can be used as the input for the plant for manufacturing biogas that is rich in methane, an efficient fuel that causes very little pollution. The biogas thus produced can be used for domestic purposes, such as cooking.

Answer:

1. Underground pipes that carry wastewater are called sewers.
2. Natural decomposers cannot break down non-biodegradable waste.
3. Wastewater generated by industries is called industrial effluent.
4. Industrial wastewater and municipal wastewater are major causes of river pollution.
5. Organic matter is decomposed by aerobic bacteria in aeration tanks.
6. The solids that separate out from sewage after the action of bacteria are referred to as primary sludge.



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