Exercises: Wastewater Management | Class 7 Oxford Science: Chapter Notes, Worksheets & Tests PDF Download

Objective Type Questions 

An excessive growth of algae causes eutrophication.
Eutrophication is caused by excessive nutrients in water bodies, leading to the growth of plants and algae. This growth can cause oxygen depletion and harm aquatic life.

Q.2. (Sewer/Onsite disposal) system is a channel system of pipelines used to carry sewage. 

Sewer system is a channel system of pipelines used to carry sewage.
Sewer systems are used to collect and transport sewage from households and buildings to treatment plants.

Q.3. Air is blown into the sewage in __________ (sedimentation/aeration) tanks. 

Air is blown into the sewage in aeration tanks.
Aeration tanks are used in sewage treatment to introduce oxygen into the wastewater. This helps to promote the growth of aerobic bacteria, which break down organic matter.

Q.4. ____________(LPG/Biogas) is produced by the action of bacteria on the organic matter of the sludge.

Biogas is produced by the action of bacteria on the organic matter of the sludge.
Biogas is produced through the anaerobic digestion of organic matter by bacteria. This process can be used to treat sewage sludge and produce a renewable energy source.

Q.5. ____________(Earthworms/Ants) are used to convert human excreta into compost in vermi-composting toilets.

Earthworms are used to convert human excreta into compost in vermi-composting toilets.
Vermi-composting toilets use earthworms to break down human waste and convert it into compost. This process is a sustainable way to manage waste and produce fertilizer for plants.

Choose the Correct Option.

Very Short Answer Type Questions 

Sewerage

Q.2. Facility that treats wastewater from domestic as well as industrial sources  _________

Wastewater treatment plant

Q.3. Light waste that rises to the top and floats in sedimentation tanks during primary treatment of wastewater  _________

Scum

Q.4. The water that comes out of the sedimentation tanks after the completion of primary process ______

Effluent

Q.5. Burning of sludge to ashes  __________

Incineration

Short Answer Type Questions 

The different sources of wastewater are domestic households, industries, hospitals, schools, and other public places.

Q.2. How does a sewer system function? 

A sewer system functions by collecting wastewater from different sources and transporting it to a treatment plant for treatment. The wastewater flows through pipes that are laid underground and are connected to each other. The sewer system is designed to ensure the smooth flow of wastewater without any blockages.

Q.3. How can we convert sludge into useful substances? 

Sludge can be converted into useful substances by a process called sludge treatment. Sludge treatment involves separating the solid and liquid components of the sludge. The solid component is then treated with chemicals to make it safe for use as fertilizer or as fuel for power plants.

Q.4. Why is it important to maintain proper sanitation in public places?

It is important to maintain proper sanitation in public places to prevent the spread of diseases. Poor sanitation can lead to the transmission of diseases like cholera, typhoid, and hepatitis A. Proper sanitation practices like handwashing, clean water supply, and proper disposal of waste can prevent the spread of these diseases.

Long Answer Type Questions 

Measures to control the generation of sewage:

a. Educating people on the importance of reducing water usage. They can be advised to fix leaking taps, use low-flow showerheads, wash clothes only when necessary, etc.

b. Encouraging the use of biodegradable products like soaps, detergents, and cleaning agents.

c. Encouraging people to compost food waste and use it as manure for plants.

d. Promoting the use of public toilets and ensuring their proper maintenance.

e. Encouraging industries to install treatment plants to treat their wastewater before releasing it into the environment.

f. Encouraging the use of water-efficient appliances and technologies.

Q.2. Discuss the problems faced due to improper management of wastes.

Problems faced due to improper management of wastes:

a. Air and water pollution due to untreated sewage and industrial waste.

b. Contamination of soil and groundwater due to the release of chemicals and heavy metals from waste.

c. Spread of diseases due to the breeding of mosquitoes and other disease-causing organisms in stagnant water.

d. Damage to marine life due to the release of waste into water bodies.

e. Loss of biodiversity and habitat destruction due to the dumping of waste in natural areas.

Q.3. Explain alternative methods of sewage disposal.

Alternative methods of sewage disposal:

a. Constructing septic tanks to treat sewage at the household level.

b. Setting up decentralized treatment plants to treat sewage in small communities.

c. Constructing wetlands to treat sewage using natural processes.

d. Recycling sewage for irrigation purposes.

e. Constructing bio-toilets in public spaces and remote areas where conventional sewage systems are not feasible.