Chapter 3
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47
sewer lines. Factories must treat their
wastewater before it is allowed to travel
through sewer lines. Sometimes, factories
and people dump waste materials into
rivers and lakes. Both state and local
governments have passed laws to control
this type of pollution.
Polluted water can cause disease in
humans and animals. Wastewater must be
treated tomake it clean again.Dirtywater is
treated at wastewater
treatment plants
.
Perhaps youhave seen a treatment plant in
your area. Wastewater goes through many
steps at the treatment plant to make it
clean. Finally, the water is treated with
chlorine to kill any remaining germs in the
water. After the water has beenmade clean
again, it can be recycled, or returned, to
rivers and streams. We must all work to
keep our salt and freshwaterforms clean.
Keeping Our
Land Clean
A
nother concern for Pennsylvanians
is keeping the land on which they
live clean. Until recently, we have
thought only to throw things away when
we no longer need them. People throw
away tons and tons of garbage, or solid
wastes, each year. They are hauled to large,
open areas called
landfills
. Then, the solid
wastes are buried under soil.
There are three big problems with
landfills. One problem is that these solid
wastes do not decay for hundreds of years.
For instance, it takes aluminum thousands
of years to decay in the soil. Landfills also
take garbage from factories. Some factories
send poisonous materials sealed in metal
Recycling thematerials we use, such as glass, aluminum,
and paper, helps us with our solidwaste problem.
