Water Pollution and Solutions 8.4
In addition to primary and secondary treatment, many sewage plants use tertiary
treatment to clean wastewater. (Tertiary means “third.”) The chart below shows which
materials are removed in each treatment step. The thickness of the black bar shows how
much of each substance remains in the water. Use the chart to answer the following
questions on a separate piece of paper.
1.
2.
3.
4.
Which materials are partly removed by secondary treatment?
Which materials are mostly removed by primary treatment?
Which materials does tertiary treatment help remove?
If a sewage plant did not use tertiary treatment, which material(s)
would not be removed at all?
5. Which materials are completely removed before the treated water
is released into the environment after chlorination treatment?
6. Phosphorus and nitrogen are nutrients that help algae and plants
grow. Why is it important to reduce these materials before treated
water is released?
Water Pollution and Solutions 8.4
Write the letter of the correct answer on the line at the left.
1. ___ About 97% of the water on Earth is
A fresh water
B groundwater
C salt water
D ice
3. ___ The water and human wastes that are
washed down sinks, showers, and toilets are
called
A the water cycle
B sewage
C thermal pollution
D point pollution sources
2. ___ Water that causes erosion picks up
A sediments
B sewage
C pollutants
D algae
4. ___ Chemicals that kill crop-destroying
organisms are called
A sediments
B fertilizers
C acid rain
D pesticides
If the statement is true, write true. If the statement is false, change the underlined
word
or words to make the statement true.
5. _____________ Most water pollution is the result of natural processes.
6. _____________ Industry washes agricultural wastes, including animal wastes,
fertilizers, and pesticides, into ponds, causing algae to grow.
7. _____________ Wastes produced by agriculture, households, industry, mining,
and other human activities can end up in water.
8. _____________ Fresh liquid water is stored in soil and rock beneath Earth’s
surface.
9.
_____________ Keeping water clean requires effective cleanup of oil and
gasoline spills, proper sewage treatment, and reduction of pollutants
10. _________ Most communities treat groundwater before returning it to the
environment.