CBSE Class 7 Science Chapter 13 Important Questions - Wastewater Story

Very Short Answer Questions: (1 Marks)

Fill in the Blanks:

1. The United Nations declared the period from 2005-2015 as the International Decade for _______________. 

Ans: Action on the water for life 

2. The suspended impurities in sewage are called _________________.

Ans: Contaminants 

3. The network of small and big pipes that is used for the transport of sewage from the point of production to the point of treatment is called __________________. 

Ans: Sewerage 

4. The sewage that originates from the kitchen is called as _____________. 

Ans: Sullage 

5. Foul waste originates from __________________. 

Ans: Toilets and bathrooms 

6. Wastewater generated by the industries is called as __________________. 

Ans: Trade water 

7. _______________ are used to remove large objects from wastewater. 

Ans: Bar screens 

8. Solid component of sewage is called as _______________. 

Ans: Sludge 

9. Aerobic bacteria that settle in the bottom of the tank after clarification are referred to as ________________. 

Ans: Activated sludge 

10. Septic tanks, chemical toilets and composting pits are examples of ___________________.

Ans: On-site composting

Short Answer Questions: (3 Marks)

1. What is the importance of sewage treatment?

Ans: Sewage is wastewater produced by households and businesses. As a result, it contains material that is hazardous to human health. Water and solid stuff such as faeces make up sewage. If sewage is not treated, the organic stuff in it provides ideal circumstances for the growth of bacteria and other potentially harmful carrier organisms. These organisms have the potential to cause sickness in both humans and animals. Furthermore, sewage has a foul odour that is nauseating and can induce a variety of ailments. Due to a shortage of clean water, this is impossible.

2. How is activated sludge formed?

Ans: The clarified water is then transported to an aeration tank for additional treatment. An aerator is used to introduce air into the cleared water, allowing aerobic bacteria to flourish. These aerobic bacteria then eat any organic substance that remains in the cleared water, such as human waste, food waste, soaps, and so on. These suspended aerobic bacteria settle to the bottom of the tank as activated sludge after many hours.

3. What is the role of grit and sand removal tanks?

Ans: The grit and sand removal tank is a progressively sloped tank where heavier particles such as grit and sand can settle. The pace of water in this tank is substantially slowed. Heavy particles in the wastewater, such as grit and sand, sink to the bottom of the tank when water runs at a near-stagnant rate. After that, the water is transported to the clarifier.

4. How is water clarified in a water clarifier?

Ans: The clarifier is a huge tank with a centre slope. Water is allowed to settle for several hours in this tank. During this time, the sewage's organic solid particles settle at the bottom of the tank. Sludge refers to the solid element of sewage. A scraper is used to scrape and remove the sludge. A skimmer is used to remove floatable materials like oil and grease. Clarified water is the water that is obtained at the end of this operation. The sludge is then moved to a separate tank, where anaerobic bacteria decompose it into biogas and compost. Manure can be utilised as fertiliser and biogas can be used to generate electricity.

5. What are onsite composting methods?

Ans: On-site composting systems treat sewage at the point of production rather than transporting it to a treatment facility. Septic tanks, chemical toilets, compost pits, and other on-site composting technologies include septic tanks, chemical toilets, and compost pits, among others. Such on-site solutions can be used because the volumes of sewage created by tiny units are lower than those generated by a large population. The action of bacteria composts sewage, and cleaned wastewater is subsequently reintroduced into the sewers. The burden on the sewage treatment plants is reduced as a result.

Long Answer Questions: (5 Marks)

1. Suggest better housekeeping practices that can be adopted to reduce waste generation.

Ans: We can utilise a variety of housekeeping methods to reduce sewage and our environmental impact.

1. Cooking fats and oils solidify and clog drains. As a result, they should not be flushed down the toilet.

2. Chemicals can destroy critical sewage-treatment bacteria, therefore they shouldn't be flushed down the toilet.

3. Solid wastes should not be poured down the sink since they clog it. They also obstruct oxygen flow, which has a negative impact on the deterioration process.

4. Do not pollute the environment. If there isn't a garbage bin available, the trash should be transported home and disposed of in the trash can.

2. Poor sanitation leads to diseases. Justify.

Ans: The maintenance of hygiene at the communal level is referred to as sanitation. It entails proper sewage disposal and sustaining communal cleanliness. Sanitation issues imply that hygiene is not being maintained. This happens as a result of incorrect sewage disposal. This allows disease-causing microorganisms and their vectors to reproduce. A rise in the number of pathogenic bacteria increases the chance of developing numerous diseases. Poor sanitation also has an impact on the supply and availability of safe drinking water.  In the lack of safe drinking water, a variety of health issues occur, which can lead to a variety of diseases. In addition, due to a shortage of clean water, recovering from infections would be difficult.

5 Important Topics of Class 7 Science Chapter 13 You Shouldn’t Miss!

In Chapter 13 Wastewater Story, students explore essential topics related to wastewater management, treatment processes, and their impact on health and the environment.

Benefits of Class 7 Science Important Questions Chapter 13 Wastewater Story

• Important Questions help students focus on the main ideas of wastewater treatment, ensuring a solid understanding of the chapter.

• Practising these questions prepares students for assessments by familiarising them with the types of questions they may encounter.

• Answering Important Questions encourages students to think critically about wastewater management and its environmental impact.

• Reviewing Important Questions aids in the long-term retention of key concepts by breaking down complex information into manageable parts.

• These questions often relate to real-life scenarios, helping students understand the practical implications of wastewater treatment.

• Regular practice of Important Questions boosts students' confidence in their understanding of the material, making them more prepared for exams.

Conclusion

In conclusion, the Important Questions for Class 7 Science Chapter 13, Wastewater Story, serve as a valuable resource for reinforcing key concepts related to wastewater management and its environmental significance. By actively engaging with these questions, students can enhance their understanding of the treatment processes, the importance of clean water, and the impact of wastewater on health and ecosystems. 

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