Treatment of Domestic Water | Chemistry for Grade 11 (IGCSE) PDF Download

Water supply

• Water is sourced from rivers, reservoirs, or subterranean water bodies like groundwater.
• An aquifer refers to a geological formation capable of storing water.

Water Treatment

• Raw water contains both soluble and insoluble impurities.
• Insoluble impurities consist of soil, plant fragments, and organic matter.
• Soluble impurities include dissolved calcium, metallic compounds, and various inorganic pollutants.
• Water is directed into sedimentation tanks where it remains stationary for several hours.
• Sedimentation occurs as gravity causes mud, sand, and other particles to settle at the tank's bottom, forming a sediment layer.
• Filtration involves passing water through layers of sand and gravel filters to capture smaller particles.
• Additionally, water can be filtered through activated carbon, typically in charcoal form, to eliminate tastes and odors.
• Chlorination is employed to eradicate bacteria and microorganisms that cannot be trapped by filters.
• Chlorine is carefully added to the water to kill harmful bacteria and microorganisms.
• Untreated water consumption can lead to bacterial infections such as cholera and typhoid.
• Diagram showing the stages in the treatment of water: