Water treatment
Purifying water
Water taken straight from the natural environment, such as water from rivers and lakes. contains dissolved ions, Microscopically small organism, such as a bacterium or single-celled fungus. Also called a microorganism., pollutants and Unable to dissolve in a particular solvent. For example, sand is insoluble in water. materials like sand and stones. Water is treated to remove any harmful components before being fed into the public supply. This is done in several ways.
- Sedimentation 鈥 the water is stored in a large tank or a reservoir. This slows down the flow of the water and allows large, insoluble particles to settle to the bottom. The cleaner water at the top can then be extracted for the next stage.
- Filtration 鈥 the water is sprayed onto specially-prepared layers of sand and gravel. As it trickles through, smaller insoluble particles are removed. The filter beds are cleaned periodically by pumping clean water backwards through the filter.
- Chlorination 鈥 chlorine gas is injected into the water to To kill any living organisms, usually microbes that might cause disease, on an object or in a substance. it. The chlorine is poisonous and so kills microorganisms.
Water is purified by sedimentation, filtration and the addition of chlorine