Class 7 Science Question Answers - Wastewater Management

Short Types Questions

Sources of wastewater include domestic households, industrial processes, and agricultural activities.

Q.2. What are contaminants present in sewage?

Sewage often contains contaminants such as bacteria, viruses, chemicals, and solid waste.

Q.3. What is eutrophication and how is it caused by wastewater?

Eutrophication is the excessive growth of algae and other aquatic plants due to the presence of nutrients in water. Wastewater contains high levels of nutrients, which can lead to eutrophication in nearby water bodies.

Q.4. What is primary treatment in wastewater management?

Primary treatment is the initial stage of wastewater treatment that involves physical processes such as screening and sedimentation to remove large solids and debris from the wastewater.

Q.5. What are alternative methods of sewage disposal?

Alternative methods of sewage disposal include composting toilets, septic tanks, and constructed wetlands. These methods can be used in areas where traditional sewer systems are not feasible or cost-effective.

Long Types Questions

Wastewater is generated from various sources such as domestic households, industries, hospitals, and commercial establishments. It contains various types of contaminants such as organic matter, nutrients (nitrogen and phosphorus), pathogens (bacteria, viruses, and protozoa), heavy metals, and toxic chemicals. Domestic wastewater contains mainly organic matter and nutrients, while industrial wastewater contains heavy metals, toxic chemicals, and other pollutants depending on the industry.

Q.2. Describe the process of eutrophication and its impact on aquatic ecosystems.

Eutrophication is the process of excessive growth of algae and other aquatic plants due to the presence of high levels of nutrients (nitrogen and phosphorus) in the water. The excessive growth of algae leads to the depletion of oxygen in the water, which can lead to the death of fish and other aquatic organisms. It also affects the quality of water and makes it unsuitable for human consumption and recreational activities.

Q.3. Explain the primary, secondary, and tertiary treatment processes in wastewater treatment plants.

Primary treatment involves the physical removal of large solids and floating materials from wastewater through processes such as screening, sedimentation, and flocculation. Secondary treatment involves the biological removal of organic matter and nutrients using microorganisms such as bacteria and protozoa in aeration tanks. Tertiary treatment involves the advanced removal of nutrients and other contaminants through processes such as filtration, disinfection, and chemical treatment.

Q.4. Describe the sewer system and its components.

The sewer system is a network of pipes that collects and transports wastewater from households, industries, and other sources to the wastewater treatment plant. It consists of a collection system, which includes gravity pipes, lift stations, and force mains, and a treatment system, which includes primary, secondary, and tertiary treatment processes.

Q.5. Discuss the importance of controlling sewage generation and promoting environmental awareness.

Controlling sewage generation is important to reduce the quantity of wastewater generated and to prevent the contamination of water bodies and groundwater. This can be achieved through various methods such as water conservation, reuse, and recycling, and the use of alternative methods of sewage disposal. Promoting environmental awareness is important to create awareness among people about the importance of water conservation, wastewater management, and the impact of human activities on the environment. This can be achieved through various methods such as education, campaigns, and community participation.