Objetivos: Fazer leitura instrumental.
Topico: Água Potável.
Interdiscipinaridade: Geografia/Ciências
 

THE WATER WE DRINK

The water we drink usually comes from reservoirs, lakes, or rivers. A large number of cities uses river water and dumps it back into the river. Sometimes another city downstream uses the same water. This water may be badly contaminated with chemicals and pathogenic bacteria. Many different chemical treatments are necessary to make it safe and palatable.

Chemical engineers usually place the water into a setting basing to purify it. Then, they treat it with slaked lime  and aluminum sulfate. The chemical reaction of these elements forms a gelatinous mass. This mass carries down dirty particles and bacteria.

Many communities add some form of fluoride to their water. Fluoride in concentrations of 0.7 to 1.0ppm can significantly reduce tooth decay in children.

Some communities, usually the smaller ones, obtain water from wells. Even they have problems because sometimes the ground water is contaminated. In some parts of the country the contamination of nitrate in well water is above the maximum safe level of 2.0 ppm. These nitrates come from agricultural fertilizers and from the decomposition of organic wastes.

What can we do! We can fight for clear water and convince our neighbors to do the same. We can de4mand an end to water pollution by industries and cities. And finally, we must know how to use the water of the earth because that is all we have.

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