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Environmental Health
Water is absolutely essential to maintain life. Water
is required by the people for the purpose of drinking, cooking and washing
of the body, clothes, household, farm animals, etc. The body needs water to maintain
the fluidity of the blood, to keep the tissues soft and elastic, excretion and
secretion, and to maintain the body temperature. We get water from the
environment, which becomes polluted due to various factors. The
main agents of water pollution are human beings themselves. water may get polluted due to
population explosion, improper disposal of excreta and sewage, use of
pesticides for agriculture, waste
products released by factories, etc. In fact, water is called polluted when it
contains pathogenic germs, dust, organic matter, chemical substances, and other
harmful elements.
Water is most essential for the
maintenance of life, but if it is polluted, it can also work as a vehicle to carry several and
widespread water borne diseases such as:
i)
Cholera,
ii)
Diarrhoea,
iii)
Dysentery, and
iv)
Typhoid.
Mode of Water Contamination
Water is contaminated through the human excreta,
sewage, washing of contaminated utensils, clothes, and the agents of diseases.
When a person uses such contaminated water he/she may suffer from different types of
diseases.
Methods of Water Purification
In fact, water is never pure in a
chemical sense. Even clean and clean water may contain the germs of diseases. So, water must
be purified before use. Water can be purified in various ways. Some of them
are:
i)
Boiling: It is a
satisfactory method of purifying water for household purposes. While using this
method, water must be brought to a ‘rolling’ boil. Boiling should be done for
5-10 minutes. Boiling destroys all forms of diseases-producing organisms
usually found in water. When water is boiled, the container becomes sterilised
or water should be boiled Preferably
in the same container.
ii)
Sedimentation and
Decantation: it is a natural method of water purification. In this
method,
water is collected from the sources and stored in a jar or container. The water
if
allowed
to remain for some time in the container, the impurities (e.g. stone, sand,
chalk,
mud,
etc.) will settle down at the bottom. We will be able to pour out the water
without
disturbing
the impurities. This process of water filtration is called sedimentation
and it
Serves
the following purpose:
. The solid matter in suspension falls to the bottom by gravity and is
called the sediment.
.
Organic matter is destroyed through oxygenation.
.
Bacterial count is also reduced.
iii)
Sand Filtration:
This is also called the filtration of water by four pitchers system. It is an old-fashioned
filter system. In this method, the four pitchers are placed one above the other
on a wooden stand. All the vessel except the last one has small pores at the
bottom. The
uppermost vessel contains thick layer of charcoal which is filled with water
and which percolates through a hole of the second pitcher.
The second pitcher contains a layer of
sand, and the third contains gravel. Water drips into each of these vessels.
The last of fourth pitcher contains filtered water.
Nowadays, one can buy a manufactured
filter from the market. The principle of these filters is that water is made to
pass through porous ‘candles’ and in doing so it is purified.
iv)
Chlorination: One
of the most widely used disinfectants for treating drinking water is chlorine
and when it is added to water in proper proportion, it is affective in killing pathogenic
organisms. Besides, water may be purified by SODIS method. In this method, water
is collected in colourless plastic bottles and kept in sunlight for about six
hours.
