Read the text. Using a dictionary, translate it in writing.
TEXT A. Water Quality.
Water Pollution and Water Treatment
“High quality water is more than the dream of the conservationists, more than a political slogan; high quality water, in the right quantity at the right place at the right time, is essential to health,
recreation, and economic growth.” EDMUND S. MUSKIE, U.S. Senator, speech, 1 March 1966
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The development of human society, the growth of civilization and so- cial and technological progress has resulted in the changing of the com- position of natural water resources. Natural waters contain a considerable amount of the products of mechanical, chemical and biological pollution. Untreated water contains a number of contaminants of natural and man- made origin, the presence of which is undesirable or dangerous.
For better understanding the process and objectives of water treat- ment, we should consider the nature of water pollution and the notion of water quality.
Water pollution is contamination of water by undesirable foreign matter (materials such as waste effluents, chemicals, detergents, and fer- tilizers and pesticides) which deteriorates water quality. Water quality has a microbiological and a physicochemical dimension. There are thou- sands of parameters of water quality. The type and extent of water treatment depends on the quality of the water source. The better the quality, the less treatment is needed.
In its purest form, water is simply H2O; that is, two atoms of hydro- gen attached to each atom of oxygen. Water is called the "universal sol- vent" because of its strong tendency to dissolve other substances. Be- cause water is such a good solvent, in the environment it will always contain dissolved or suspended impurities.
The quality of water is determined by the presence of various sub- stances of organic and inorganic origin, as well as microorganisms in it. Undesirable impurities can be contained in water in three different states: 1 – in suspension – as separate suspended solids (coarse suspension); 2 – in colloidal state; 3 – in solution – as dissolved solids.
All identified water contaminants [pollutants] are typically divided into the following types:
· suspended solids (fine, non-settling particles of any solid);
· heavy metal ions (ions of metals of relatively high density);
· dissolved organic matter (compounds, chiefly of biological origin, containing carbon);
· microorganisms (microscopic organisms, esp. a bacterium, virus, or fungus);
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· phytoplankton (plankton consisting of microscopic plants) / zoo- plankton (plankton consisting of small animals and the immature stages of larger animals).
Another classification of pollutant foreign matter can be made into:
· non-living water contaminants;
· living water contaminants (many of which are disease-causing).
The types of impurities found in water can be divided into four groups: microbial, physical, chemical, and radiological.
| Types of Impurities | Examples | ||
| Microbial (Microorganisms) | |||
| Bacteria Viruses Protozoa Other | Campylobacter, Legionella Hepatitis Cryptosporidium, Giardia Cyanobacteria (blue-green algae) | ||
| Physical | |||
| Colour Taste and odour Appearance | Iron, dissolved organic matter Methyl isoborneol Silt, suspended particles, plankton | ||
| Chemical | |||
| Naturally occurring Agricultural Water treatment Plumbing Industrial | Manganese, nitrate Atrazine, chlordane Chlorine, fluoride Lead, copper Polyaromatic hydrocarbons, mercury | ||
| Radiological
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