Chemistry-Water Cape Unit 2

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  • Topic: Water, Water purification, Oxygen
  • Pages : 3 (621 words )
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  • Published : January 30, 2013
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a) describe the importance of the water cycle
b) discuss the methods of water purification (include desalination via reverse osmosis) c) discuss the importance of dissolved oxygen to aquatic life d) discuss the sources of water pollution (include nitrates, phosphates, heavy metals (lead and mercury), cyanides, trace metals, pesticides, herbicides, petroleum reside, suspended particles) e) assess the impact of the pollutants in part d) above on the aquatic environment

Module 3 Water & its importance

Water Cycle

Water cycle is essential for the continued supply of water on the earth’s surface. Our bodies are made of about 65% water and thus all metabolic activities require water to be present. We cannot easily make MORE water, so we must depend on the water cycle for our present supply of it.

Water Purification
In many cases, the water obtained from nature is not pure enough for our needs, whether it is drinking or bathing or even for industrial processes. Hence a series of purification steps must be conducted in order for the water to be used for our various purposes.

Please note that desalination can also be considered a process of water purification via the use of reverse osmosis

Sedimentation
The water, after coagulation, is left in settling basin further for sufficient period to allow sedimentation of remaining materials. Sedimentation however considerably reduces microbial population of the water aside from removing most of the suspended particles.

Filtration
After sedimentation, water is subjected to sand filters to remove flocks of living organisms. The process of filtration is highly critical and important as it can remove protozoan cysts and also about 98-99% of bacteria from water. The water may also be filtered through activated charcoal to remove potentially toxic organic compounds and organic compounds that impart undesirable colour and/or taste to the water.

Disinfection
Disinfection is the final step is municipal...
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