Name: ______________________
Date: _________
_____ / 35
Water Treatment
Background:
The goal of water treatment is to eliminate organic and inorganic wastes in water. Organic waste
consists of fecal matter which contains bacteria, such as Escherichia coli. E. coli is found in the
intestines of warm blooded animals and should not be found in drinking water. Inorganic wastes
may consist of mercury and phosphates.
Water that contains organic and inorganic impurities is treated in several steps. Water from a
lake, river or stream enters the water treatment plant and undergoes sedimentation, a step when
large particles are separated from the water. Next, flocculation occurs as special chemicals are
added to the water to cause organic materials to bind to each other. This results in clumps
called flocs which sediment out. The water will then go through a filtration process. Finally,
chlorine is added to the water to kill any harmful microbes. The chlorine will also treat the pipes
that carry the water from the treatment facility to your homes.
Like water treatment, sewage treatment is a process to treat water so it is safe to release into
the environment. Sewage water undergoes a primary, secondary, and sometimes tertiary
treatment. During the primary treatment phase, the waste water is screened and then
undergoes sedimentation. When the water reaches the secondary treatment phase, the water
experiences activated sludge aeration. Oxygen is pumped into the sewage to increase the
activity of the bacteria. The bacteria are now more activity in digesting the sludge. A sewage
plant may also have a trickling system. This system consists of round vats with sprayers. Like
the aeration system, the trickling system also aids bacteria in digesting sludge. Finally, the water
may enter a chlorination tank where the water is treated chemically to kill any remaining
bacteria. The water can then be released into a stream.
Pre-Lab Questions:
1. Explain why filtration and sedimentation are considered physical changes. (2 points)
2. Explain why chlorination is considered a chemical change. (1 point)
3. How are bacteria both beneficial and harmful in the process of wastewater treatment? (2
points)
4. What disease can develop if wastewater is not treated? (1 point)
Objective:
With the materials your teacher provides you, you will design an efficient water treatment
process to clean a sample of wastewater. In order for your cleaned water to be safely released
into the environment, it must meet the EPA requirements. Therefore, you will have to consider
both physical and chemical changes while creating your treatment process.
Wastewater:
-
water
soil
paper
plastic
vinegar
oil
pond water (microorganisms)
Treatment Materials:
-
brown paper towel
white paper towel
paper
coffee filter
beakers
cheese cloth
baking soda
bleach
soap
Procedure:
Complete the data table for each step that you take to clean your wastewater sample.
1. What treatment material did you use?
2. What waste material did this treatment method remove?
3. Describe what your water looked like after completing this step.
4. What treatment process did you simulate (sedimentation, filtration, chlorination, etc)?
5. Was this a physical or chemical treatment?
Data Table: (15 points)
Material
What
removed?
Observations
Treatment
Process
Physical/
Chemical
Analysis/Conclusion:
1. Identify the followings wastes as organic or inorganic: (3 points)
Soil
Paper
Plastic
Vinegar
Oil
pond water (microorganisms)
2. Why is it important to remove solid wastes from water? (1 point)
3. Why is it important to kill microorganisms from the water? (1 point)
4. What was the most effective treatment method? Why? (2 point)
5. What was the least effective treatment method? Why? (2 points)
6. Did your water meet EPA standards? If so, explain why your procedure was successful.
If not, explain how you could modify your process to achieve a better result. (5 points)