Pict. 8. Types of Impurities Found in Water
“Water quality” is a term used to describe the chemical, physical, and biological characteristics of water, usually in respect of its suitability for a particular purpose (for drinking, industrial purposes, irrigation, recrea- tion, etc.) Although scientific measurements are used to define water quality, it’s not a simple thing to say “this water is good/ pure”, or “this water is bad/ impure”. There are complex interconnections among fac-
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tors such as surface and ground water, atmospheric and climatic factors, natural landscape features (such as geology, topography, and soils), hu- man activities, and aquatic health which must be taken into account in analyzing water quality.
The quality of water from natural water sources as well as water qual- ity requirements for various water users vary greatly.
By analyzing water from natural sources the presence of various sub- stances and microorganisms is determined. For obtaining the correct characteristics of water from the given water source, water sampling and analyses should be done for a long period of time in order to take into account seasonal changes of water quality.
Water treatment is purification of water to make it suitable (i.e. pota- ble and palatable) for human consumption or for other purposes. It is any of several physical and chemical processes (or a combination of these processes) in which undesirable impurities and pollutants in water are removed or neutralized.
The primary objective of water treatment is the protection of the health of the community. Palatable potable water is the water that must be bacteriologically safe, free from toxic or harmful microorganisms, chemicals or substances, as well as crystal clear and comparatively free of turbidity, colour, odour and taste. Excessive hardness and high con- centration of dissolved solids are also undesirable, particularly for indus- trial purposes. Industrial requirements may be even more stringent; many industries provide special treatment on their own premises.
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Decide whether the following statements are true or false accord- ing to the text.
1. Factors such as the development of human society, the growth of civi- lization and social and technological progress have resulted in the changing of the composition of natural water resources.
2. There is no obvious interconnection among water quality, water pollu- tion and water treatment.
3. Water treatment is the presence of undesirable impurities in water.
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4. Water pollution is the removal of undesirable foreign matter from wa- ter.
5. Water pollution is contamination of water by undesirable foreign mat- ter which improves water quality.
6. There are no parameters of water quality.
7. The worse the quality of water, the more water treatment is needed.
8. In its purest form, water is simply H2O; that is, two atoms of hydrogen attached to one molecule of oxygen.
9. Since water is a good solvent, in the environment it will always contain dissolved or suspended impurities.
10. Undesirable impurities can be contained in water in three different states: in suspension, in colloidal state and in solution.
11. Water contaminants include dissolved solids and suspended organic matter.
12. Pollutants may be either living or non-living, either of natural or of man-made origin.
13. Many living microorganisms in water are disease-causing ones.
14. The types of impurities found in water can be divided into microbio- logical, physicochemical and radioactive.
15. Manganese, chlorine, copper, lead and mercury are examples of physi- cal water impurities.
16. “Water quality” is a term which describes chemical and physical char- acteristics of water.
17. Water can be used for various purposes: for drinking, industrial pur- poses, irrigation, recreation, etc.
18. In analyzing water quality, numerous factors must be taken into ac- count.
19. Water sampling and analyses are done to determine the presence of various substances and microorganisms in water from natural sources.
20. Only a combination of several physical and chemical processes in which undesirable impurities in water are removed or neutralized can be called water treatment.
21. Palatable drinking water must not contain toxic or harmful microorgan- isms, chemicals or substances.
22. Drinking water must always be purer than water for industrial purpos- es.
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6. Answer the following questions.
1. What are the main reasons for the recent changing of the composi- tion of natural water resources?
2. Why should we consider the nature of water pollution and the no- tion of water quality?
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3. What is water pollution?
4. What dimensions does water quality have?
5. Is there the only one parameter of water quality?
6. What does the type and extent of water treatment depend on?
7. What are the classifications of water pollutants?
8. What does the term “water quality” describe?
9. Is it easy to say “this water is good/ pure” or “this water is bad/ im- pure”? Why? Why not?
10. What are the factors which must be taken into account in analyzing water quality?
11. What is water treatment?
12. What is the primary objective of water treatment?
13. What is palatable potable water?
14. Why do many industries provide special water treatment on their own premises?
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