Class 7 Science Chapter 13 Important Question Answers - Wastewater story

Very Short Answer Type Questions

Q1: Why should water be filtered before drinking?
Ans: Water should be filtered before drinking because it contains impurities that are not easily visible and can be harmful.

Q2: What diseases can result from drinking contaminated water?
Ans: Drinking contaminated water can result in diseases such as cholera, typhoid, and diarrhea.

Q3: What is World Water Day, and when is it celebrated?
Ans: World Water Day is celebrated on March 22nd. It was declared by the United Nations to raise awareness about the importance of clean water.

Q4: What is the purpose of sewage treatment?
Ans: The purpose of sewage treatment is to remove impurities and contaminants from wastewater, making it safe for reuse or release into water bodies.

Q5: What are the three categories of impurities found in sewage?
Ans: Sewage contains organic and inorganic impurities, disease-causing bacteria, and nutrients.

Q6: Define "clarified water" in the context of sewage treatment.
Ans: Clarified water is wastewater that has had physical impurities removed and is considered relatively clean.

Q7: What is the role of an aerator in wastewater treatment?
Ans: An aerator pumps air into wastewater, allowing bacteria to consume organic waste. It helps in the purification of water.

Q8: Why is chlorine or ozone used in water treatment plants?
Ans: Chlorine or ozone is used to disinfect water and kill disease-causing bacteria and microbes during water treatment.

Q9: What is the significance of eucalyptus trees in wastewater treatment?
Ans: Eucalyptus trees planted near sewage ponds absorb wastewater and release pure water vapor into the atmosphere, helping in water purification.

Q10: What are some common mechanisms for sewage disposal in areas without proper sanitation?
Ans: Common mechanisms for sewage disposal include septic tanks, chemical toilets, composting pits, and vermi-processing toilets.

Short Answer Type Questions

Q11: Explain why proper sanitation is crucial and the consequences of poor sanitation.
Ans: Proper sanitation is crucial because poor sanitation leads to water and soil pollution, resulting in diseases like cholera, typhoid, and dysentery. Inadequate sanitation also affects groundwater and surface water. It is a significant problem in developing countries due to factors like a lack of awareness, population growth, and inadequate infrastructure.

Q12: Describe the types of sewage and their characteristics.
Ans: Sewage can be categorized into sullage water (kitchen waste), foul waste (toilet waste), and trade waste (industrial waste). Sullage water contains mild detergents, oils, and food particles. Foul waste includes human waste and harmful bacteria. Trade waste contains toxic chemicals and acids from industries.

Q13: What is the sewerage system, and why is it important in wastewater management?
Ans: The sewerage system consists of pipes (sewers) that carry wastewater from homes and industries to treatment plants. It plays a vital role in preventing direct drainage of sewage into rivers or lakes, reducing water contamination.

Q14: Explain the stages of wastewater treatment.
Ans: Wastewater treatment involves physical, biological, and chemical processes. Physical processes include screening (bar screens) and grit and sand removal. Biological processes use bacteria to consume organic waste. Chemical processes, such as chlorination, disinfect water.

Q15: How do septic tanks work, and where are they commonly used?
Ans: Septic tanks collect and treat sewage from isolated buildings or areas without direct sewage connections. Bacteria break down organic waste in the tank, and the clarified water is released. Septic tanks are common in rural areas or places without centralized sewage systems.

Q16: Describe the composting toilet system and its environmental benefits.
Ans: Composting toilets convert human waste into organic compost and soil. Micro-organisms and earthworms break down waste into minerals. This system is environmentally friendly, as it reduces water pollution and produces compost.

Q17: What are vermi-composting toilets, and how do they work?
Ans: Vermi-composting toilets use earthworms to treat human excreta. Earthworms help in breaking down waste into vermi-compost. It is a low-cost and eco-friendly sanitation solution.

Q18: Explain the concept of Sulabh toilets and their benefits.
Ans: Sulabh toilets are a twin-pit pour flush toilet system used by millions daily. Waste goes to biogas plants, producing biogas and bio-fertilizers. Biogas serves as a low-cost fuel source.

Q19: Why should people be aware of proper waste disposal practices, especially in public places?
Ans: Proper waste disposal in public places is essential to prevent sanitation problems and diseases. Awareness helps in maintaining cleanliness and hygiene, reducing the risk of water and soil contamination.

Q20: How can governments and organizations address sanitation issues in areas with inadequate infrastructure?
Ans: Governments and organizations can implement low-cost onsite sewage disposal systems like septic tanks, chemical toilets, composting pits, and vermi-processing toilets. They can also raise awareness about proper sanitation practices and provide necessary facilities in underserved areas.