Wastewater Story Class 7 Science Chapter 13 CBSE Notes - 2025-26

1. Waste Water

• Water that has been drained out from the sink, showers, toilet, laundries etc. is called wastewater

• It is of black brownish colour which is rich in a lather, oil, suspended impurities etc.

2. Water Our Lifeline:

• Clean water is a basic need of a person for survival.

• Earth has 71% water still there is water scarcity and clean water is not available to everyone.

• Inability to access clean water leads to many water-related diseases.

• Cleaning of water is a process of removing pollutants before it enters a water body or is reused, pollutants are substances that cause contamination.

• This process of treating wastewater to remove pollutants is usually referred to as sewage treatment.

3. What is Sewage?

• Sewage is a liquid waste produced by the community of people.

•  Sewage is essentially the wastewater that is released by houses, industries, hospitals, offices and rainwater that has run down the street during a storm or heavy rainfall.

• Sewage contains disease-causing bacteria and other microbes which can spread a lot of diseases.

• Discharging of sewage into the river body contaminates our source of freshwater and leads to water scarcity and other problems.

• It is also threatening the life of aquatic animals and plants.

• Therefore, sewage should be treated before discharging into water bodies.

4. Water Freshens Up-An Eventful Journey:

• The liquid waste i.e., sewage goes to the point of disposal from the point of being produced through the network of big and small pipes called sewers.

• These sewers form sewerage.

• Manholes are a small covered opening in a paved area allowing access beneath, especially one leading to a sewer and are located at every 50 m to 60 m within the sewerage.

• Manholes are found at the junction of two or more sewers and at points where there is a change in direction.

• Wastewater through the sewerage reaches the wastewater treatment plant where it has to go through a different method of treatment.

• After treatment and purification, it is discharged into water bodies and available for use.

5. Wastewater Treatment Plant:

• It is a facility where physical, chemical and biological processes are used to treat the wastewater.

• In the wastewater treatment plant, firstly wastewater is passed through bar screens which remove large objects like rags, sticks, cans, plastics etc.

• Water then goes to a grit and sand removal tank. The process of removing grit and sand is known as screening.

• The water is then allowed to settle in the large tank which is sloped towards the centre to separate sludge.

• After this, the sludge is transferred to an aeration tank where it is decomposed by the anaerobic bacteria and air is pumped to assist aerobic bacteria to grow.

• Bacteria consume unwanted matter still remaining in the water.

• The activated sludge contains water this water is removed by sand drying beds or machines.

• It is necessary to disinfect water chemically with chlorine and ozone to kill unwanted bacteria and microbes.

6. Better Housekeeping Practices:

• Sewage formation should be decreased as it leads to the pollution of water.

• We must adopt some measures such as:

• Not throwing vegetable oil and fats down the drain

• Chemicals should not be discharged into the drain as they may kill the microbes that help purify water.

• Throwing used tea leaves, kitchen waste, soft toys, sanitary towels, etc. in the dustbin.

7. Sanitation and Disease:

• Poor sanitation and contaminated drinking water are the major causes of the spreading of various diseases like cholera, typhoid, polio, meningitis, hepatitis and dysentery.

• Excreting in open areas leads to water and soil pollution and these untreated human excreta are harmful to our health which indirectly goes into our body.

8. Alternative Arrangement for Sewage Disposal:

1. On-site Sewage Disposal System

• These toilets do not require scavenging.

• Excreta from these toilets are directed into a biogas plant. 

• The biogas produced is employed as a source of energy.

2. Sanitation at Public Places:

• The government has laid down certain standards of sanitation in public places.

• We all should contribute to maintaining sanitation in public places.

• We should not scatter litter anywhere as it will lead to pollution.

Importance of Chapter 13 Wastewater Story Class 7 Notes

Class 7 Science Chapter 13, Wastewater Story, provides a comprehensive introduction to the concepts of forests and their importance in the environment. Here's a summary of the key points covered in the chapter:

1. Enhanced Understanding: Notes simplify and clarify complex information about forests and their role in the environment, making it easier for students to grasp essential concepts.

2. Efficient Revision: They provide a concise summary of key points, helping students quickly review and retain important details for exams and quizzes.

3. Structured Learning: Notes organise information systematically, ensuring that students can follow a logical progression of topics and build a solid understanding.

4. Visual Aids: They often include diagrams, charts, and illustrations that visually represent information, aiding in better comprehension and recall.

5. Support for Self-Study: Comprehensive notes serve as a valuable resource for independent study, allowing students to review and learn at their own pace.

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

Here are the important topics from Class 7 Science Chapter 13, Wastewater Story, that you shouldn't miss:

1. Importance of Sanitation and Clean Water: Understanding why proper sanitation is vital for health and hygiene.

2. Wastewater and Sewage: Explanation of what wastewater is, and how sewage is managed in urban areas.

3. Sewage Treatment Plant (STP): The process involved in treating wastewater before releasing it into the environment.

4. Steps of Sewage Treatment: Detailed explanation of physical, biological, and chemical processes in sewage treatment.

5. Wastewater Management: The need for effective wastewater management and recycling.

6. Role of Individuals in Maintaining Sanitation: Simple actions students can take to conserve water and ensure hygiene.

Tips for Learning the Class 7 Science Chapter 13 Wastewater Story

Here are some tips for learning Class 7 Science Chapter 13, Wastewater Story, according to the NCERT syllabus:

1. Understand Key Definitions: Focus on the definitions of wastewater, sewage, sanitation, and sewage treatment plants. These terms form the foundation of the chapter.

2. Study the Sewage Treatment Process: Pay close attention to the different stages of sewage treatment—primary, secondary, and tertiary. Draw a flowchart to simplify your understanding.

3. Real-Life Examples: Relate the chapter's concepts to real-life situations, such as how wastewater is treated in your city or how sanitation is maintained in daily life.

4. Focus on Diagrams: Study the diagrams of a sewage treatment plant and understand the functions of different parts. Visualizing the process helps in better retention.

5. NCERT Questions: Practice the exercises and questions provided at the end of the chapter in the NCERT textbook to ensure a thorough understanding of the topics.

Conclusion

Chapter 13, Wastewater Story, emphasises the importance of proper wastewater management and sanitation for a healthy environment. It explains how sewage is treated and the significance of conserving clean water. By understanding the stages of sewage treatment, students gain awareness of how essential it is to keep our surroundings hygienic and sustainable. Vedantu’s notes make these concepts easier to grasp, helping students prepare for exams with confidence and clarity, while also encouraging responsible water usage in daily life.

Related Study Materials for Class 7 Science Chapter 13 Wastewater Story

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