Water Purification

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Water Purification:

Water that exists naturally in earth is never pure. There are always impurities in it, sometimes in large amounts. In fact water could very well be contaminated with diseases and bacteria. This is why water has to be purified before it is put to use. Water purification involves two processes (Filtration & Chlorination) done in several steps:

  1. Water is taken from reservoirs or any other source to the water treatment plant
  2. Water is passed through filters to remove large, floating objects such as pieces of rocks or mud
  3. Smaller particles are removed by adding aluminum sulfate which makes them stick together in large pieces and settle down
  4. Water is passed through sand and gravel filters which filter off small particles and may kill some bacteria (filtration is done)
  5. Chlorine gas is bubbled through the water to kill all bacteria living in the water making the water sterile
  6. The water may end to be slightly acidic, small amounts of sodium hydroxide are added to treat this. Fluoride might be added to because it helps in preventing tooth decay
  7. Water is then delivered to homes

Air Pollution:

Pollution is the presence of harmful substances. Air pollution is the presence of pollutant gases in the air. A pollutant is a substance that causes pollution. These are:

  • Carbon monoxide
  • Oxides of nitrogen
  • Sulphur dioxide
  • Lead compounds

Carbon Monoxide: Carbon monoxide (CO) is one of the poisonous pollutants of air. It is considered a pollutant because it can kill living organisms. The main source of carbon monoxide is factories which burn carbon-containing fossil fuels since CO is one of the products of the incomplete combustion of fossil fuels. Carbon monoxide could be treated by installing catalytic converters in chimneys of the factories.

Sulphur Dioxide: Sulphur dioxide (SO2) is considered a pollutant since it contributes to acidic rain. Sulphur dioxide is a product of two process, these are combustion of sulphur –containing fossil fuels and extraction of metals from their sulphide ores (such as zinc sulphide). The problem associated with sulphur dioxide is that when it rises in the air from chimneys of factories, it mixes with water vapour of clouds and air. This results in the formation of sulphuric acid (H2SO4). When it rains, rain water which falls becomes acidic. Acid rain causes death…


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