Ch 18 follows the journey of wastewater from our homes to the treatment plant and back to water bodies. Students learn the cleaning process and the importance of sanitation.
Sewage from homes travels through underground sewer pipes to a Wastewater Treatment Plant (WWTP). Steps: bar screen (removes large debris) → grit/sand removal → sedimentation (solids settle as sludge) → aeration (bacteria decompose organic matter using oxygen) → final treatment → clean water released into rivers.
Proper sanitation prevents disease: do not throw cooking oil/chemicals down the drain. Use low-phosphate detergents. Sludge from treatment plant can be dried and used as manure or to produce biogas. Open drains spread disease — covered sewage systems are essential.
Download: https://ncert.nic.in/textbook/pdf/gesc118.pdf | Complete book: https://ncert.nic.in/textbook/pdf/gesc1ps.zip
Untreated sewage pollutes water bodies: bacteria consume oxygen (killing fish), toxic chemicals harm aquatic life, disease-causing organisms spread waterborne diseases (cholera, typhoid). This is why treatment before discharge is essential.
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