NCERT Exemplar Solution for Class 7 Science Chapter-18 Wastewater Story: A Precious Resource
Clean water is essential for healthy living, but after being used in homes, industries, schools, and hospitals, water becomes contaminated and turns into wastewater. Chapter 18, Wastewater Story, helps students understand how dirty water is produced, how it affects health and the environment, and how it can be treated before being released back into nature. The chapter explains sanitation systems, sewage treatment plants, water pollution, and the importance of hygiene in maintaining public health. It also teaches students the value of safe disposal of waste and responsible use of water resources. The NCERT Exemplar Solution for class 7 provides detailed explanations and application-based questions that help learners understand these environmental and scientific concepts clearly. By practicing the NCERT Exemplar Solution, students improve conceptual understanding and analytical thinking skills. Many learners searching for reliable NCERT solutions for class 7 use exemplar exercises to strengthen preparation for examinations and gain awareness about environmental protection.
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Wastewater and Its Sources
Wastewater is water that has been used and contains impurities such as soap, oils, food waste, chemicals, dirt, and harmful microorganisms. Water from kitchens, bathrooms, toilets, factories, and hospitals becomes wastewater after use. This contaminated water is commonly called sewage.
Sewage contains many harmful substances that can spread diseases if not treated properly. Human waste, detergents, chemicals, and microorganisms present in sewage can pollute rivers, lakes, and groundwater. Therefore, proper sewage management is necessary for maintaining public health and environmental safety. The chapter explains that untreated wastewater can cause serious diseases such as cholera, typhoid, dysentery, and hepatitis. These diseases spread through contaminated water and poor sanitation. Maintaining cleanliness and proper drainage systems helps prevent the spread of infections.
Modern cities use underground sewer systems to carry wastewater safely away from homes and buildings. Sewers transport sewage to sewage treatment plants where it is cleaned before being released into water bodies. In many rural areas, septic tanks are used for wastewater disposal and treatment. Students also learn the importance of sanitation and hygiene. Proper disposal of waste, regular cleaning of surroundings, and avoiding open defecation help keep the environment clean and healthy. The chapter encourages awareness about community hygiene and responsible civic behavior.
Sewage Treatment and Water Purification
Sewage treatment is the process of removing pollutants and harmful substances from wastewater. This treatment makes water safer before it is released into rivers or reused for certain purposes. Sewage treatment plants use physical, biological, and chemical methods to clean wastewater.
The first stage of treatment involves removing large objects such as plastic bags, sticks, and rags through screening. After this, wastewater passes through sedimentation tanks where heavy solids settle down as sludge. Oils and grease float on the surface and are removed separately. In the next stage, air is pumped into the wastewater to encourage the growth of helpful bacteria. These bacteria break down organic waste and help clean the water naturally. This biological process is an important part of wastewater treatment.
After treatment, cleaner water is released into rivers or lakes, while sludge can be processed to produce manure or biogas. Proper wastewater treatment helps reduce water pollution and protects aquatic life from harmful chemicals and waste materials. The chapter also highlights alternative sanitation methods such as composting toilets and eco-friendly waste disposal systems. These methods are useful in areas where proper sewage systems are not available.
Students learn that everyone can contribute to reducing water pollution by avoiding the disposal of cooking oil, chemicals, medicines, and plastic materials into drains. Responsible habits at home play a major role in maintaining clean water resources.
Importance of NCERT Exemplar Questions for This Chapter
The NCERT Exemplar Solution and exercises for this chapter are highly useful because they focus on environmental awareness and practical understanding. Questions related to sewage treatment, sanitation, pollution control, and hygiene help students connect scientific concepts with real-life situations.
These solutions improve conceptual clarity by explaining difficult terms and processes in easy language. Students can revise important topics quickly and gain confidence in answering school examination questions. Diagram-based questions related to sewage treatment plants also improve visual learning and scientific observation skills. The chapter develops awareness about public cleanliness and environmental responsibility. Students understand how improper waste disposal affects health and nature. Through regular practice of exemplar questions, learners improve logical thinking and answer-writing abilities.
Exemplar solutions also encourage students to think about sustainable living and community hygiene. The knowledge gained from this chapter is useful not only for academic learning but also for adopting healthier and cleaner habits in daily life.