ALCA Members PLC Domains Data Standards Map Plan Curriculum Assessment Strategies

How Do We Recycle Waste Water? Copy

What happens to water that goes down your drain? If three-fourths of the Earth's surface is covered with water, do we need to worry about running out of water? This activity explains why we do need to worry about our water supply and how we treat water that goes down the drain.

Engaging Questions

  • If three-fourths of the Earth is covered with water, why is it necessary for humans to worry about the water supply?

  • Which of the cleaning processes seemed to make the most change in the "swamp water?"

Teacher Goals

  • Students will use gram and liter measurements to conduct experiments which demonstrate the procedures used by municipal water plants to purify water for drinking.

  • Students will collect data from the local waste water treatment plant and write a general statement that represents the data.

Required Resources

  • Printer or "Paint" software program
    Students may print the "Earth's Water Grid" and use cayrons to color it. Or, copy the grid to a "Paint" software program to color it on the computer.


  • Materials needed for demonstration projects

    • 5 liters of "swamp water" (or add 2 cups of dirt or mud to 5 liters of water)
    • 1 two liter plastic soft drink bottle with its cap
    • 2 two liter plastic soft drink bottles, one bottle with the top removed and the other with the bottom removed
    • 1 one and one-half liter (or larger) beaker or another soft drink bottle bottom
    • 20 grams of alum (approximately 2 tablespoons; available in the spice aisle in the grocery store)
    • Fine sand (about 800 mL in volume)
    • Coarse sand (about 800 mL in volume)
    • Small pebbles (about 400 mL in volume)
    • 1 large (500 mL or larger) jar
    • 1 coffee filter
    • 1 rubber band
    • 1 tablespoon
    • A clock with a second hand or a stopwatch

  • Community water treatment plant

  • Digital camera

    A regular 35 mm camera can substitute for a digital camera if a scanner is available to digitize the images.
     

  • Community Water Treatment Plant Description

    After a trip to your community water treatment plant, write a description of the processes used to clean your waste water. Take digital photographs of the plant processes in action to compare with other water treatment plants.
     

  • How Do We Recycle Waste Water?

    Answer each of the following questions by checking "yes," "no," or writing the answer in the "answer" column. You have successfully completed this activity when all questions are answered. Give the completed rubric to your teacher.
     

Optional Resources

  • EPA Water: Geographic Information
    This web site is from the U. S. Environmental Protection Agency. The site has a link to The Water Where You Live site which includes information organized by state, and a link to the Where does My Drinking Water Come From? site which provides information by county.
     

  • Office of Wastewater Management
    Another web site from the U. S. Environmental Protection Agency, Office of Water, this site is specifically about wastewater, water pollution, solutions, and recycling.
     

Steps

  1. Earth's Water Concept Map

    1. Click on the Internet link below to learn how much of the Earth's water is usable and available.
    2. Answer the following questions about the Earth's water (you may write your answers on the "Earth's Water" rubric):
        How much of the Earth's water is not usable?
      1. Why is it not usable?
      2. How much of the Earth's water is usable?
      3. How much of the Earth's water is usable and available?

  2. Earth's Water Grid

    1. Click on the link below to view an Earth's Water Grid.
    2. You may print the grid and use crayons to color the squares to represent the amount of the Earth's water that is not usable, usable but not available, and usable and available.
    3. You may choose to copy the image into a "Paint" software program to color; the directions for copying the grid into a paint program follow.
    4. To copy the image and paste it in your paint program do the following:
      1. Open the file
      2. Hold down the mouse and a window will appear. Choose COPY THIS IMAGE.
      3. Open your paint program.
      4. Go to "File" and choose "Paste."
      5. To color a square in the paint program, click on the paint can and the color you want to use.
      6. Next, click on the squares that you want to be that color. Make sure to use the same colors that are shown in the grid key.
    5. Show your completed grid to your teacher when finished.

  3. Aeration

    1. Pour about 1.5 liter of "swamp water" into a 2 liter bottle. Describe the appearance and smell of the water; you may record your description on "The Earth's Water" rubric.
    2. Place the cap on the bottle and shake the water for 30 seconds. Continue the aeration process by pouring the water into either one of the cut-off bottles, then pouring the water back and forth between the cut-off bottles 10 times. Describe any changes you observe; you may record your description on "The Earth's Water" rubric.
    3. Pour the aerated water into a bottle with its top cut off.

  4. Coagulation

    1. Pour the aerated water into a bottle with its top cut off.
    2. Add 20 g or alum crystals to the swamp water.
    3. Slowly stir the mixture for 5 minutes.
    4. Describe any changes that you observe. (You may record your descriptions in The Earth's Waters Rubric.)

  5. Sedimentation

    1. Allow the water to stand undisturbed in the bottle. Observe the water at 5 minute intervals for a total of 20 minutes.
    2. Describe any changes you observe after 5 minutes, 10 minutes, 15 minutes and finally at 20 minutes; you may record your descriptions on "The Earth's Waters" rubric.

  6. Filtration

    Construct a filter from the bottle with its bottom cut off as follows:

    1. Attach the coffee filter to the outside neck of the bottle with a rubber band. Turn the bottle upside down and pour a layer of pebbles into the bottle; the filter will stop the pebbles from falling out of the bottle neck.
    2. Pour the coarse sand on top of the pebbles.
    3. Pour the fine sand on top of the coarse sand.
    4. Clean the filter by slowly and carefully pouring 5 liters of clean tap water through the filter. Try not to disturb the top layer of sand as you pour the water.
    5. After a large amount of sediment has settled in the bottom of the bottle of swamp water, carefully pour the top two-thirds of the swamp water through the filter. Collect the filtered water in the beaker. Pour the remaining swamp water back into the collection container.
    6. Compare the treated and untreated water. Did the treatment change the appearance and smell of the water? You may record your comparison in the "Earth's Waters" rubric.

  7. Field Trip to Community Water Treatment Plant

    Visit your local waste water treatment plant. Notice each of the processes used to clean the water. Take digital photographs of the cleaning processes in action. Write a description of the processes used in your community's waste water treatment plant. Add this description and the photographs to the Data Form.
     

Teacher Notes

  • Hint: washed, natural color aquarium rocks will work for the small pebbles.

  • Aeration is the addition of air to water. This allows gases trapped in the water to escape and adds oxygen to the water.

    Coagulation is the process by which dirt and other suspended solid particles are chemically "stuck together" so that they can be removed from water.

    Sedimentation is the process that occurs when gravity pulls the clumps of alum and sediment to the bottom of the bottle.

    Filtration through a sand and pebble filter removes most of the impurities remaining in water after coagulation and sedimentation have taken place.

    NOTE: The final step at the treatment plant is to add disinfectants to the water to purify it and kill any organisms that may be harmful. Because the disinfectants are caustic and must be handled carefully, this step is not presented in this activity. Therefore, the water that was just filtered in this activity is NOT SAFE to drink.

  • The Earth's Water activity will take 15 minutes. The Water Treatment demonstrations will take 45 minutes. The field trip duration will vary according to distance and tour guide.

Learner Notes

  • Aeration is the addition of air to water. This allows gases trapped in the water to escape and adds oxygen to the water.

    Coagulation is the process by which dirt and other suspended solid particles are chemically "stuck together" so that they can be removed from water.

    Sedimentation is the process that occurs when gravity pulls the clumps of alum and sediment to the bottom of the bottle.

    Filtration through a sand and pebble filter removes most of the impurities remaining in water after coagulation and sedimentation have taken place.

    NOTE: The final step at the treatment plant is to add disinfectants to the water to purify it and kill any organisms that may be harmful. Because the disinfectants are caustic and must be handled carefully, this step is not presented in this activity. Therefore, the water that was just filtered in this activity is NOT SAFE to drink.
     

Mentor Notes

  • Aeration is the addition of air to water. This allows gases trapped in the water to escape and adds oxygen to the water.

    Coagulation is the process by which dirt and other suspended solid particles are chemically "stuck together" so that they can be removed from water.

    Sedimentation is the process that occurs when gravity pulls the clumps of alum and sediment to the bottom of the bottle.

    Filtration through a sand and pebble filter removes most of the impurities remaining in water after coagulation and sedimentation have taken place.

    NOTE: The final step at the treatment plant is to add disinfectants to the water to purify it and kill any organisms that may be harmful. Because the disinfectants are caustic and must be handled carefully, this step is not presented in this activity. Therefore, the water that was just filtered in this activity is NOT SAFE to drink.

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