Chapter 18 – Wastewater story

These NCERT Class 7 Science Chapter 18 notes explain what happens to water after it is used in homes, schools, hospitals, and industries. The chapter helps students understand that used water becomes wastewater and contains harmful substances that can pollute the environment.

Wastewater Story describes sewage, sewerage systems, and the working of sewage treatment plants in a simple way. It also highlights the importance of sanitation, hygiene, and safe disposal of wastewater for protecting public health and the environment.

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1. Introduction: why wastewater management matters

•  Water used in homes, schools, hospitals, and industries becomes wastewater.
•  Wastewater contains dirt, chemicals, and disease-causing germs.
•  If released untreated, it pollutes water bodies and spreads diseases.
•  Dirty water must be cleaned before returning to nature.

2. What is wastewater

•  Wastewater is used water that has become contaminated.
•  It is also called sewage.
•  Sources include kitchens, bathrooms, toilets, industries, and hospitals.

3. What is sewage

•  Sewage contains human waste, food waste, soap and detergents, and chemicals.
•  It also contains microorganisms that can cause diseases.

4. Importance of wastewater treatment

•  Treatment prevents water pollution.
•  It protects human health and saves aquatic life.
•  Treated water becomes reusable.

5. Sewerage system

•  A sewerage system is a network of underground pipes.
•  These pipes, called sewers, carry sewage to treatment plants.

6. Sewage treatment plant (STP)

•  A sewage treatment plant cleans wastewater before release.
•  It removes harmful substances and germs from sewage.

7. Steps of sewage treatment

•  Screening removes large objects like rags and plastics to prevent blockage.
•  Grit and sand removal allows sand and stones to settle down.
•  Primary treatment separates sludge and scum from water.
•  Biological treatment uses bacteria to break down organic waste.
•  Treated water is released into rivers or reused.

8. Sludge management

•  Sludge is collected and dried.
•  It is used as manure or for producing biogas.

9. Sanitation and public health

•  Poor sanitation leads to diseases like cholera, typhoid, and dysentery.
•  Clean surroundings reduce the disease burden in India.

10. Role of toilets in hygiene

•  Toilets prevent open defecation.
•  They reduce the spread of diseases.
•  Toilets improve dignity and safety.

11. Good sanitation practices

•  Always use toilets.
•  Do not throw solid waste into drains.
•  Keep surroundings clean and save water.

12. Sanitation at home

•  Do not throw cooking oil, plastic, medicines, or sanitary waste into drains.
•  Such waste can block drains and harm treatment systems.

13. Wastewater recycling

•  Treated water can be reused for gardening and industries.
•  It is also used for cleaning roads.

14. Role of government and citizens

•  The government builds sewerage systems and treatment plants.
•  Citizens must follow hygiene and sanitation rules.

15. Environmental impact of untreated sewage

•  Untreated sewage pollutes rivers.
•  It kills aquatic life and spreads epidemics.

16. Importance of clean water

•  Clean water is essential for health.
•  It supports development and protects the environment.

17. Important keywords with simple definitions

•  Wastewater – used and contaminated water.
•  Sewage – wastewater containing waste and germs.
•  Sewerage – system of pipes carrying sewage.
•  Sewage treatment plant – place where wastewater is cleaned.
•  Sludge – solid waste separated during treatment.
•  Sanitation – practices for maintaining cleanliness and health.

Understanding NCERT Class 7 Science Chapter 18 – Wastewater Story is important to learn how wastewater is treated and why sanitation is essential for a healthy society. The chapter clearly explains sewage treatment, recycling of wastewater, and the role of citizens and government.

The ideas discussed in this chapter are highly useful for school examinations and foundation-level science preparation, especially for topics related to environment and public health.

FAQs

Q1. What is explained in NCERT Class 7 Science Chapter 18?
The chapter explains wastewater, sewage treatment, sanitation, and public health.

Q2. What is wastewater?
Wastewater is used water that contains dirt, waste, and harmful microorganisms.

Q3. What is a sewage treatment plant?
A sewage treatment plant cleans wastewater before releasing it into water bodies or reusing it.

Q4. Why is sanitation important?
Sanitation prevents the spread of diseases and keeps surroundings clean.

Q5. Why is NCERT Class 7 Science Chapter 18 important for exams?
It explains sanitation, wastewater management, and environmental protection, which are important topics for school and foundation-level exams.

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