Remove Microplastics from Water with Bioremediation

This project follows the Scientific Method. Review the steps before you begin.

Prepare Each Jar

1. Add 3.0 grams (g) of glitter to each jar.
   1. To weigh out the glitter, cut a small piece of wax paper (around 8 centimeters [cm] to 10 cm on each side), place the wax paper on the scale, zero out the scale (so that it reads “0 g”), and then weigh out the glitter on the wax paper, as shown in Figure 2.
2. Add 0.5 g, 1.0 g, or 2.0 g of yeast to each jar. Add no yeast to the fourth jar.
   1. Weigh out the yeast as you did for the glitter in step 1a.
   2. Label each jar with how much yeast is in the jar.
3. Add 200 mL of water to each jar.
   1. Use the graduated cylinder to measure and pour the water.
4. Each cup should now be filled almost to the top, with some empty space between the top of the liquid and the jar’s lid, as shown in Figure 3.
5. Screw the caps onto each jar securely.

Image Credit: Teisha Rowland / Science Buddies

Weighing glitter on a digital scale.

Figure 2. Scale being used to weigh out the glitter.

Image Credit: Teisha Rowland / Science Buddies

Jar of glitter, yeast, and water.

Figure 3. Jar prepared with glitter, yeast, and water.

Shake the Jars

1. Shake each jar at high speed for 2 minutes (min).
   1. Use a timer, stopwatch, or clock to keep track of time.
   2. Have a helper shake two of the jars (one in each hand) so all jars are shaken similarly and start at the same time.
   3. Shaking vigorously will help mix the yeast and glitter.
2. Shake each jar at a lower speed for an additional 5 min.
   1. Repeat the shaking as you did in step 1, but at a lower speed.
   2. This will help ensure the yeast and glitter are thoroughly mixed.
3. Set all jars next to each other in a flat, out-of-the-way location (such as a table or counter) where they will not be moved or bumped for the next hour. Also, make sure there is enough light to make observations.

Observe the Jars

1. Leave the jars undisturbed for 60 min, but make and record observations during this time.
   1. In your lab notebook, create a data table similar to Table 1.
   2. Record any observations at the indicated times (0, 15, 30, 45, and 60 min).
      1. How does the glitter look in each jar?
         1. At the 0 min timepoint, the glitter in the jar with no yeast (i.e., your control) should be floating at the top.
      2. Can you tell where the yeast is in the jars?
      3. Do the jars with the yeast look different in some way? How do they look similar?
   3. After 60 min, without moving the jar as much as possible, carefully remove the lid from each jar and perform final observations. Record these observations in your data table, too.
      1. Is there glitter floating on the top of the water? If yes, how is the amount of floating glitter in each jar similar or different?
      2. Where is the glitter in each jar?
      3. Where is the yeast in the jars with yeast?

Measure the Suspended or Floating Glitter

1. Set up a strainer with a coffee filter and place the strainer over a large container to collect the liquid that flows through. Your setup should look similar to Figure 4. You will be using this setup to collect the glitter floating and suspended in each jar.

Image Credit: Teisha Rowland / Science Buddies

Coffee filter in a strainer over a large cup viewed from the side

Image Credit: Teisha Rowland / Science Buddies

Coffee filter in a strainer over a large cup viewed from the top.

Figure 4. Set up with a coffee filter sitting inside a strainer, both placed over a large container to collect the liquid that flows through.

2. Slowly pour the jar with no yeast through the coffee filter, but stop pouring before any glitter that has settled on the bottom is disturbed. You will stop pouring to ensure you measure only the glitter that is floating or suspended in each jar, not the glitter that has settled to the bottom.
3. After the liquid has flowed through:
   1. Carefully lift off the coffee filter and set it aside to dry.
   2. Use a marker or pen to label the edge of the coffee filter with the sample that you poured through it.
4. Repeat steps 2 to 3 with a new coffee filter in the strainer, and this time slowly pour the jar with 2.0 g yeast through the coffee filter. As before, stop pouring before any layer of settled glitter or yeast is disturbed. Again, you want to ensure you measure only the glitter floating or suspended in each jar, not the settled glitter at the bottom.
5. Repeat step 4 with the remaining two jars.
6. While each coffee filter is drying, make a data table like Table 2 in your lab notebook.
7. After each coffee filter has completely dried, which may take at least an hour, weigh the glitter on it and record the weight in Table 2.
   1. Zero out the scale (so that it reads “0 g”) using a fresh coffee filter.
   2. Then weigh each coffee filter with the glitter on it from the jar.
      1. Tip: Be sure each coffee filter is completely dry, or your weight measurements will be inaccurate.

8. Repeat the procedure two more times. Scientists always repeat their experiments to make sure their findings are true and reproducible.
9. When you are done with your experiment, do not pour any glitter down the sink, but instead dispose of it by sealing it in a bag and placing it in the trash.
10. What do your results tell you about which conditions lead to glitter sinking and settling to the bottom of each jar?
    1. Which jar had the most glitter still floating or suspended after 60 min?
    2. Which jar (or jars) had the most glitter settle to the bottom?
    3. How much yeast is needed to cause glitter to settle to the bottom?
    4. How do the jars with yeast compare to the control jar (with no yeast)?
    5. What do your results tell you about potential bioremediation strategies for microplastics?
    6. Can you think of ways to improve upon the bioremediation strategy that was most successful in your science project? You can also check out the Variations section, below, for additional ideas.