PHANG XIN RU 2 SAPPHIRE SCIENCE FORM 2 CHAPTER 5: WATER AND SOLUTION 5.3 WATER PURIFICATION AND WATER SUPPLY
1.Water from natural resources may contain: - Impurities such as particles of soil and suspended particles - Chemical substances and dissolved mineral salts - Microorganisms such as disease-causing protozoa and bacteria - Unpleasant smell, taste and colour 2.There fore, we must purify water before use. We can purify water in many ways. (a) Filtration • Eliminates big-size suspended particles • Does not eliminate fine suspended particles, dissolved substances and does not kill microorganisms in water • Not safe to drink because still contains microorganisms (b) Chlorination • Chlorine is used in liquid form and poisonous substance • Kills microorganisms in the water • Does not eliminate dissolved substances and suspended particles • Excessive use gives an uneasy smell and is harmful to health (c) Boiling • The boiling point of water is 100°C at normal atmosphere pressure • Kills the microorganisms in water • Does not eliminate dissolved substances and suspended particles (d) Distillation • Produces distilled water • Eliminates suspended impurities, dissolved substances and microorganisms • Not suitable for drinking because the water does not contain any mineral salts needed by the body 5.3 WATER PURIFICATION AND WATER SUPPLY FILTRATION :
WATER SUPPLY SYSTEM 1. Filtration - Eliminates large suspended particles like leaves, tree branches and others 2. Oxidation - Increases the oxygen content in the water to eliminates smell and taste that are not comfortable 3. Coagulation - Alum is added to coagulate the suspended particles, whereas slaked lime is added to reduce the acidity in the water 4. Sedimentation - Suspended particles that have coagulated deposit at the bottom of the tank 5. Filtration - Eliminates remnants of suspended substances using a sand filter 6. Chlorination - Kills microorganisms in the water 7. Fluoridation - prevents tooth decay
1. TYPES OF POLLUTANTS: Industrial waste NEGATIVE EFFECTS: Poison aquatic life, causes cancer, changes the water pH causing the aquatic organisms to die CONTROL MEASURES: Taking legal actions against factories those disposal, treating waste before disposal 2. TYPES OF POLLUTANTS: Agriculture waste NEGATIVE EFFECTS: Pesticides that are non-biodegradable will remain in the water and will transfer through the food chain CONTROL MEASURES: Educate the farmer using fertilisers and pesticides correctly 3. TYPES OF POLLUTANTS: Domestic waste NEGATIVE EFFECTS: Detergent reduce dissolved oxygen in the water, this causes the death of a lot of aquatic organisms CONTROL MEASURES: Recycle all paper, plastic, glass and metals 4. TYPES OF POLLUTANTS: Logging and building construction NEGATIVE EFFECTS: Mud and sand will follow into the water and make the river shallow and cause flashfloods CONTROL MEASURES: Plan the location of new residential areas in detail WATER SUSTAINABILITY
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