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Picture courtesy of: http://www.epa.gov/
1) Jar, 2) plants, 3) water, 4) soil, 5) sand. 6) pebbles
Water filtration activity:
Water in lakes, rivers, and swamps often contains impurities that make it look and smell
bad. The water may also contain bacteria and other microbiological organisms that can cause
diseases. That is why water must be cleaned before it can be drunk by people.
Water treatment plants do this job! They clean the municipal water you receive at home if you
live in developed countries. Below is the explanation of what does a treatment plant.
Picture courtesy of: http://www.epa.gov/
In the treatment plant, water goes through a
series of cleansing processes known as:
(1)
aeration;
(2)
coagulation;
(3)
sedimentation;
(4)
filtration;
(5)
disinfection.
Coagulation removes dirt and other
particles suspended in water. Alum and
other chemicals are added to water to attract
the dirt particles. The weight of the dirt +
the alum sink to the bottom.
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Clear water moves to filtration. The water
passes through filters, some made of layers
of sand, gravel, and charcoal that help
remove even smaller particles.
Chlorine can help killing any bacteria or
microorganisms that may be in the water.
Water is placed in a closed tank for
disinfection.
The water then flows through pipes to
homes and businesses in the community.
Activity: Purify some water, but do not drink it!:
This experiment do not make water drinkable; it just makes it clear!
Collect a few Liters of soiled water.
1)
Put the water into a large bottle, then shake it vigorously. Pour water into other recipients,
then pour back into the main recipient again for a few minutes: AERATE.
2)
Add 20 g of alum crystals to the water. Stir: COAGULATION.
3)
Let the water stand half an hour to let the particles sink at the bottom of the recipient:
SEDIMENTATION.
4)
Attach a coffee filter with an elastic band at the neck of a bottle. Cut off the bottom of a
bottle. The bottle upside down, place into it a layer of pebbles, then a layer of sand. Pour the
water over it without disturbing the layer of sand to make sure it stays effective:
FILTRATION.
5)
Add disinfectants to the water to purify it and kill any organisms still present: DISINFECT.
Make sure you do not drink the water since disinfectants are dangerous for the health. Only
qualified persons know what is proper to disinfect water. Remark the color and smell of the
water now.
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