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| The sea lavender can survive on the edge of salt marshes. [view] |
Did
you know?
| Tossing
water balloons is a fun way to cool off on a hot day. Fill empty balloons
with a bit of water and then blow them up. (It's no good filling the
balloons with too much water because they'll burst immediately.) Wear
bathing suits. Two players stand close together and begin throwing a water balloon back and forth. Each time you catch the balloon, take a step backwards. The loser catches the bursting balloon. |
[Format
of print]---Print the article of this topicWater for cooling
--Natural cooling
--Cooling engines and power stations
---Water for heat storage
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Desalination People
can drink fresh water, but not salt water. If we drink salt water
we become very ill, as our body cannot cope with the salts. In places
where fresh water is in short supply, such as in desert area near
the equator, desalination plants provide an importance source of
fresh water. Desalination is a process by which the salt is removed
from the seawater. The fresh water can then be used for drinking
or irrigate crops. In the past, most desalination plants relied
on distillation to remove the salt. The salt water was placed in
a vessel and heated so that it boiled. The water vapor was drawn
off and then cooled. This causes the water vapor to condense, allowing
pure water to be collected. Impurities in the water such as salt
were left in the vessel. The water that was produced was ever purer
than normal fresh water. This method was quite expensive, because
it required a large amount of energy to boil off the water. But,
in the 1970s, a process called reverse osmosis was developed. In
this process, an artificial membrane is used to remove the molecules
of salt from the water. |
