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Glass Recycling



Given the overcrowding of our landfills and the impact they have on the environment, fewer and fewer landfills are being built. Of the ones that are, very tight regulations are imposed. Communities across the country are reacting to this by developing and encouraging the use of recycling programs. The goal is to preserve our natural resources and save precious space in our landfills. Jars, bottles, and other containers are some of the everyday objects made from glass that can be recycled. Not all glass is recyclable. Glass found in light bulbs, cookware, and window panes is made by incorporating ceramics with the glass. This type of glass is not recyclable because doing so would introduce impurities into the recycling process. Once the glass is picked up by a recycling truck, it is separated by colors. Amber and green glass is made by adding a coloring agent during the original glass-manufacturing process; this color cannot be removed. Therefore, brown bottles can only make other brown bottles. When the glass is taken to a manufacturing or recycling plant, it is broken up into smaller pieces called cullet . The broken pieces are crushed, sorted, cleaned, and prepared to be mixed with other raw materials in the glass-making process. The cost savings of recycling is in the use of energy. When glass is made from scratch, high temperatures are needed to melt and combine all the ingredients. Since cullet melts at a lower temperature, the more of it you add to a batch of raw materials, the less energy you will need to melt it. Recycling glass is not only cost-efficient; it benefits the environment in several ways. Glass produced from recycled glass instead of raw materials reduces related air pollution by 20% and related water pollution by 50%. Throwaway bottles consume three times as much energy as reusable, returnable containers. And, recycling glass reduces the space in landfills that would otherwise be taken up by used bottles and jars. Ten to twelve percent of the glass used in the United States is recycled. Much of the glass used is not recycled. According to the Earthworks Group, about 28 billion bottles and jars are thrown away every year. That's enough to fill both towers of New York's World Trade Center every two weeks.


See how compacting a container affects how much space it takes up. You will find out how the volume of a container can be measured. Using your calculations, you will see the significance of compaction as it relates to landfills. Materials
  • glass, aluminum, and plastic softdrink containers (with tops or lids) of various volumes, shapes, and sizes
  • large pail
  • pan or tray
  • water
  • graduated cylinders (250 ml or larger)
  • sand
  • tape measure
  • calculators (optional)
  • paper and pencils
  1. Divide your students into three groups. Each group will have the task of figuring out how to get the most containers into a 2-foot square area (your "landfill").
  2. Have each group select one type of container to conduct its tests on.
  3. Each group can use any method it can think of to find out how much volume its container has, i.e., how much space the container would take up in a landfill. Using the materials provided, have the students calculate the volume of the containers and record their findings on a data sheet. (Some ideas for calculating volume include immersing the container into a bucket of water and measuring the "overflow"; filling the container with sand and measuring that amount; or using a measuring tape and calculating the container's dimensions.)
  4. Next, have each group compact its container to its smallest form and repeat step 3.


    Chertow, M. (1989) Garbage solutions: U.S. conference of mayors policy
    manual. Washington, DC: National Resources Recovery Association.
    MacEachern, D. (1990) Save our planet: 750 everyday ways you can help clean
    up the earth. New York: Dell.
    The Earthworks Group (1989) Fifty simple things you can do to save the earth.
    Berkeley, CA: Earthworks.
    Russell, H. (1973) Earth: The great recycler. Nashville, TN: Thomas
    Additional sources of information:
    Environmental Protection Agency
    Office of Water and Waste Management
    Washington, DC 20460
    (EPA Booklet SW-801: Let's Recycle)
    Glass Packaging Institute
    1801 K St. NW
    Washington, DC 20006
    (202) 887-4850
    Community resources:
    Environmental specialist
    Recycling companies