Page 222 - New Medley 4 Semester 2 PDF (Merged)

Use of polluted water causes many diseases in humans like gastroenteritis, jaundice,

cholera, diarrhoea and typhoid. So we should learn the ways to prevent water
pollution.

PURIFICATION OF WATER

The dirty water needs to be purified before use. Some common methods for the
purification of water are as follows:

Sedimentation and decantation

The substances which do not Knowledge Zone
dissolve in water are called insoluble 1. A person can live without food for more

substances. The process of settling than a month but only for one week
down heavy insoluble impurities in without water.

water is called sedimentation. The 2. In the Kalahari desert, people store water
substances which settle at the bottom in the shells of ostrich eggs and bury
them in the sand to be used later.
are called sediments and the clear
water on the top is called decant.

The process of separating clear water from the sediments is called decantation.

S E L Self-Management • Hands-on Learning
Activity

Take two beakers. Put muddy water in
one beaker. Leave it undisturbed for
some time. When you feel that all the
mud has settled at the bottom, then
pour the clear water on the top into
the second beaker carefully.

Step 1 Step 2 Step 3

Filtration

The process of separating out insoluble impurities from water

by using a filter is called filtration. A muslin cloth and different
types of water purifiers are used to filter dirty water.

Water purifier

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