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Experiment: Remove microplastics from water with yeast
Дата публикации: 30-06-2026 10:30:00

Learn how yeast can be used to remove microplastics from contaminated water with this experiment.

Основное содержимое страницы с новостью.

Objective: In this science project, you’ll investigate how much yeast is needed to remove microplastics from contaminated water.
Areas of science: Environmental Science; Green Chemistry
Difficulty: Intermediate easy
Time required: Very Short (≤ 1 day)
Prerequisites: None
Material availability: Assistance ordering materials needed. See the materials list for details.
Cost: Very Low (under $20)
Safety: No issues
Credits: Teisha Rowland, PhD, Science Buddies

Plastic pollution is a major issue worldwide, and plastic production has been increasing for decades. Mass production of plastic is not sustainable for the environment, and recycling plastic alone will not address the problem of plastic pollution. Plastic pollution has negative effects on the environment, impacting ecosystems and the organisms in them, including us. Although we do not currently know whether plastics alone are harmful to human health, emerging research suggests they may be associated with human immune disorders and developmental, reproductive and neurological issues. Better understanding the impacts on animal and human health is an active area of research.

Why is plastic pollution such a big problem? Some plastics take an extremely long time to break down, or degrade, and even this process itself can cause problems. Plastics can break down into microplastics, tiny pieces 5 millimeters (0.2 inch [in]) or smaller. Microplastics may not only contain harmful chemicals but can also bind to toxins. While much remains unknown about how microplastics may affect living organisms, ingesting them (and any bound toxins) may be harmful to our bodies and ecosystems.

Nearly half of plastic pollution can float, and it ends up in the oceans or washed up on beaches. Ocean microplastics are consumed by a range of marine organisms, including fish, marine mammals and seabirds. Microplastics may also accumulate in fish that we eat. The Great Pacific Garbage Patch is a gigantic collection of marine debris — plastic and other floating trash — in the central North Pacific Ocean, weighing about 100,000,000 kilograms (kg) (220,000,000 pounds [lbs]).

Watch this video to see how the experiment is done.

Efforts are underway to tackle this enormous challenge. By the end of 2024, scientists and others with the Ocean Cleanup project had removed about 500,000 kg (1,100,000 lbs) of trash from the Great Pacific Garbage Patch, but that was only half a percent of the total amount of garbage! While only about 8 percent of plastic in the Great Pacific Garbage Patch is microplastics, larger plastic pieces continually break down, creating more microplastics, and these pieces are much harder to clean up. Plastic trash and particles are now found in most marine and terrestrial habitats, including rivers, lakes, ponds, beaches, coral reefs and the deep sea.

What can we do about plastic pollution? In this science project, you will investigate how floating microplastics can be removed from contaminated water. To clean water at a wastewater treatment plant, flocculants are added. Flocculants clump together with particles floating or suspended in the water. These clumps, called flocs, can then sink and settle to the bottom of a water container, making it easier to remove both the flocculants and the particles. This process is called flocculation. (Sedimentation is another term used to describe how particles sink and settle at the bottom of a container or body of water.)

To help make sure that flocculants do not harm organisms living in or using the water, scientists are investigating using bioremediation instead of chemicals during flocculation. Using organisms (usually microscopic organisms, or microorganisms) to remove environmental pollutants is called bioremediation. Watch the video below to learn more about bioremediation.

In this project, you will investigate how baker’s yeast (Saccharomyces cerevisiae) can be used as a flocculant to sediment microplastics in contaminated water. For the microplastics, you will use plastic glitter.

Microbes can help remove pollution from the environment, a process known as bioremediation.Terms and concepts
  • Microplastics
  • Great Pacific Garbage Patch
  • Wastewater treatment plant
  • Flocculants
  • Flocs
  • Flocculation
  • Sedimentation
  • Microorganisms
  • Bioremediation
  • Yeast
Questions
  • Why might floating microplastics be a problem in water systems such as rivers, lakes and oceans?
  • How is flocculation used in a wastewater treatment plant?
  • Do some research into flocculants used in wastewater treatment plants. How do flocculants usually work?
  • How is bioremediation different from other methods used to remove pollutants from the environment?
ResourcesMaterials and equipment
  • Common lab supplies:
  • Glitter (36 grams)
    • Standard plastic glitter should be used. The glitter should be made of polyethylene terephthalate (PET), also called polyester. It should float when mixed with water.
  • Jars with lids, 8-ounce size (4)
    • Canning jars work well for this.  
  • Wax paper (1 sheet)
  • Baker’s yeast (11 g)
  • Timer, clock or stopwatch
  • Helper for shaking the jars
  • Optional: Camera
  • Lab notebook
Experimental procedurePrepare each jar
  1. Add 3.0 grams (g) (0.1 ounce [oz]) 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 (3 to 4 in) 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 (0.02 oz, 0.04 oz or 0.08 oz) 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 1i.
    2. Label each jar with how much yeast is in the jar.
  3. Add 200 mL (about 1 cup [C]) of water to each jar.
    1. Use the graduated cylinder to measure and pour the water.
  4. Each jar 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 lids onto each jar securely.
Shake the jars
  1. Shake each jar at high speed for two 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 five 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 time point, 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, carefully remove the lid from each jar, moving the jar as little as possible, 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?
No Yeast0.5 g (0.02 oz) Yeast1 g (0.04 oz) Yeast2 g (0.08 oz) Yeast
0 min
15 min
30 min
45 min
60 min
Table 1. In your lab notebook, make a data table like this one in which to record your observations and results over time.Measure the suspended or floating glitter

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.

  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.
  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 (0.08 oz) 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.
No Yeast0.5 g (0.02 oz) Yeast1 g (0.04 oz) Yeast2 g (0.08 oz) Yeast
Weight of suspended or floating glitter (g)
Table 2. In your lab notebook, make a data table like this one in which to record your observations and results over time.
  1. Repeat the procedure two more times. Scientists always repeat their experiments to make sure their findings are true and reproducible.
  2. 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.
  3. 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.
Variations
  • In this project, you used baker’s yeast in your bioremediation experiments. What other organisms could you use to test their ability to remove water pollutants?
  • This science project involved adding baker’s yeast to clean up contaminated water. While such an approach may work for cleaning contaminated wastewater, adding baker’s yeast may not be as feasible for cleaning contaminated waters in the ocean and other natural water systems. What other methods could be used to safely and efficiently remove microplastics from natural water systems? 
  • Biofilms may trap floating microplastics. Do some research into biofilms. How could you safely test the ability of biofilms to remove floating microplastics from contaminated water?
  • Here, you used glitter as an example of microplastics. Explore what other types of microplastics pollute water systems. How could you test ways to remove other types of microplastics from contaminated water?
  • Biodegradable hydrogels are being explored for their potential to safely remove pollutants from water. How could you test the ability of hydrogels to remove pollutants from water? 
  • Do some research into other types of pollutants that contaminate various water systems, such as rivers, lakes and oceans. For example, dyes and high levels of sugars can pollute some water systems. Pick a different type of pollutant and research how it can be removed from water. How could you test how effective different approaches are in removing your chosen pollutant from contaminated water?
  • Some microplastics can bind to toxins, making their ingestion more hazardous. Can you design a way to model this, for example, by exposing different plastics to different dyes and measuring how well each plastic changes color when stained with each dye?

This activity is brought to you in partnership with Science Buddies. Find the original activity on the Science Buddies website.

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Power Words More About Power Words

biofilm: A gooey community of different types of microbes that essentially glues itself to some solid surface. Living in a biofilm is one way microbes protect themselves from stressful agents (such as poisons) in their environment.

chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

control: (n.) A part of an experiment where there is no change from normal conditions. The control is essential to scientific experiments. It shows that any new effect is likely due only to the part of the test that a researcher has altered. For example, if scientists were testing different types of fertilizer in a garden, they would want one section of it to remain unfertilized, as the control. Its area would show how plants in this garden grow under normal conditions. And that gives scientists something against which they can compare their experimental data. (v.) To include some unchanged or unaffected conditions in an experiment so their results could later be contrasted with those from where changes had been made.

coral: Marine animals that often produce a hard and stony exoskeleton and tend to live on reefs (the exoskeletons of dead ancestor corals).

data: Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning. For digital information (the type stored by computers), those data typically are numbers stored in a binary code, portrayed as strings of zeros and ones.

degrade: To break down into smaller, simpler materials — as when wood rots or as a flag that’s left outdoors in the weather will fray, fade and fall apart. (in chemistry) To break down a compound into smaller components.

developmental: (in biology) An adjective that refers to the changes an organism undergoes from conception through adulthood. Those changes often involve chemistry, size and sometimes even shape.

digital: (in computer science and engineering)  An adjective indicating that something has been developed numerically on a computer or on some other electronic device, based on a binary system (where all numbers are displayed using a series of only zeros and ones).

disorder: (in medicine) A condition where the body does not work appropriately, leading to what might be viewed as an illness. This term can sometimes be used interchangeably with disease.

economy: Term for the combined wealth and resources (people, jobs, land, forests and minerals, for instance) of a nation or region. It is often measured in terms of jobs and income or in terms of the production and use of goods (such as products) and services (for instance, nursing or internet access).

ecosystem: A group of interacting living organisms — including microorganisms, plants and animals — and their physical environment within a particular climate. Examples include tropical reefs, rainforests, alpine meadows and polar tundra. The term can also be applied to elements that make up some artificial environment, such as a company, classroom or the internet.

environment: The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of things in the vicinity of an item of interest).

Environmental Protection Agency: (or EPA) A national government agency charged with helping create a cleaner, safer and healthier environment in the United States. Created on Dec. 2, 1970, it reviews data on the possible toxicity of new chemicals (other than foods or drugs, which are regulated by other agencies) before they are approved for sale and use. Where such chemicals may be toxic, it sets limits or guidelines on how much of them may be released into (or allowed to build up in) the air, water or soil.

filter: (n.) Something that allows some materials to pass through but not others, based on their size or some other feature. (v.) The process of screening some things out on the basis of traits such as size, density, electric charge.

flocculant: A  chemical that promotes tiny particles suspended in a liquid to clump together. These clumps are known as flocs. When the clumps get big enough they will — depending on their density — either settle out (and fall to the bottom of the liquid) or float atop it. This process, known as flocculation, works by neutralizing the electrical charges that initially had caused the tiny particles to repel each other.

habitat: The area or natural environment in which an animal or plant normally lives, such as a desert, coral reef or freshwater lake. A habitat can be home to thousands of different species.

hydrogel: A “smart” polymer-based material that can change its structure in response to its environment, such as the local temperature, pH, salt or water concentration. The polymers that make up a hydrogel have water-attracting ends sticking out. Those ends help hydrogels latch onto molecules of water. Some hydrogels are used in baby diapers to hold urine. Others are added to potting soils to hold water near to plants until they need it. Still others may be part of wound dressings to prevent a sore from drying out.

immune: (adj.) Having to do with immunity. (v.) Able to ward off a particular infection. Alternatively, this term can be used to mean an organism shows no impacts from exposure to a particular poison or process. More generally, the term may signal that something cannot be hurt by a particular drug, disease or chemical.

liquid: A material that flows freely but keeps a constant volume, like water or oil.

mammal: An animal distinguished by possessing hair or fur, the secretion of milk by females for the feeding of their young, and (typically) the bearing of live young. They also are warm-blooded (or endothermic).

marine: Having to do with the ocean world or environment.

marine mammal: Any of many types of mammals that spend most of its life in the ocean environment. These include whales and dolphins, walruses and sea lions, seals and sea otters, manatees and dugongs — even polar bears.

mass: A number that shows how much an object resists speeding up or slowing down — basically a measure of how much matter that object is made from.

microorganism: A living thing that is too small to see with the unaided eye, including bacteria, some fungi and many other organisms such as amoebas. Most consist of a single cell.

microplastic: A small piece of plastic, 5 millimeters (0.2 inch) or smaller in size. Microplastics may have been produced at that small size, or their size may be the result of the breakdown of water bottles, plastic bags or other things that started out larger.

microscopic: An adjective for things too small to be seen by the unaided eye. It takes a microscope to view objects this small, such as bacteria or other one-celled organisms.

model: A simulation of a real-world event (usually using a computer) that has been developed to predict one or more likely outcomes. Or an individual that is meant to display how something would work in or look on others.

neurological: An adjective that refers to the brain, spinal cord or nerves.

organism: Any living thing, from elephants and plants to bacteria and other types of single-celled life.

Pacific: The largest of the world’s five oceans. It separates Asia and Australia to the west from North and South America to the east. The term can also refer to island nations that sit within the Pacific Ocean.

particle: A minute amount of something.

plastic: Any of a series of materials that are easily deformable; or synthetic materials that have been made from polymers (long strings of some building-block molecule) that tend to be lightweight, inexpensive and resistant to degradation. (adj.) A material that is able to adapt by changing shape or possibly even changing its function.

pollutant: A substance that taints something — such as the air, water, our bodies or products. Some pollutants are chemicals, such as pesticides. Others may be radiation, including excess heat or light. Even weeds and other invasive species can be considered a type of biological pollution.

polyester: A synthetic material used chiefly to make fabrics. The actual chemical name for the material used is polyethylene terephthalate.

polyethylene: A plastic made from chemicals that have been refined (produced from) crude oil and/or natural gas. The most common plastic in the world, it is flexible and tough. It also can resist radiation.

polyethylene terephthalate (PET): A commonly used type of plastic, usually referred to simply as PET. It can be produced as strong, stable fibers for use in making clothing. It also is the basis of many plastic beverage bottles (such as milk jugs) and semi-hard food packages (often used for produce). When used in fabrics, it’s simply known as polyester. To identify these plastics in goods other than clothing, they tend to carry a labeled on the bottom or side with the number 1 surrounded by the triangular "chasing arrows" symbol and the acronym PET or PETE below the triangle.

range: The full extent or distribution of something. For instance, a plant or animal’s range is the area over which it naturally exists. (in math or for measurements) The extent to which values can vary (such as the highest to lowest temperatures). Also, the distance within which something can be reached or perceived.

reef: A ridge of rock, coral or sand. It rises up from the seafloor and may come to just above or just under the water’s surface.

sea: An ocean (or region that is part of an ocean). Unlike lakes and streams, seawater — or ocean water — is salty.

sediment: Material (such as stones and sand) deposited by water, wind or glaciers.

strategy: A thoughtful and clever plan for achieving some difficult or challenging goal.

sustainable: (n. sustainability) An adjective to describe the use of resources in a such a way that they will continue to be available long into the future.

system: A network of parts that together work to achieve some function. For instance, the blood, vessels and heart are primary components of the human body's circulatory system. Similarly, trains, platforms, tracks, roadway signals and overpasses are among the potential components of a nation's railway system. System can even be applied to the processes or ideas that are part of some method or ordered set of procedures for getting a task done.

terrestrial: Having to do with planet Earth, especially its land. Terra is Latin for Earth.

toxin: A poison produced by living organisms, such as bacteria, algae and certain plants (such as poison ivy). Bees, spiders, snakes and other animals also produce toxins. These are referred to as venoms.

wastewater: Any water that has been used for some purpose (such as cleaning) and no longer is clean or safe enough for use without some type of treatment. Examples include the water that goes down the kitchen sink or bathtub or water that has been used in manufacturing some product, such as a dyed fabric.

yeast: One-celled fungi that can ferment carbohydrates (like sugars), producing carbon dioxide and alcohol. They also play a pivotal role in making many baked products rise.

A version of this article appears in the September 1, 2026 issue of Science News Explores.

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