Problem: Which Types of Landfill Materials Would Produce Usable Gases Most Rapidly During

Name School Teacher Date

Summary

Problem: Which types of landfill materials would produce usable gases most rapidly during the decomposition process?

Hypothesis: Landfills that do not contain glass or plastic materials will decompose at a faster rate than landfills that do contain glass and plastic, and thus would produce gases such as methane more effectively.

Materials: common household products: paper, plastic, glass, cloth scraps; common yard wastes: grass clippings, leaves, twigs, sticks; common food wastes: fruit and vegetable peels (meat and/or daily products are not recommended), 4 -12” diameter balloons, water, common yard soil, 4- clean 3-liter soda bottles, thermometer for each bottle, electric heat source such as a light bulb or lamp, ¼ cup commercial yard/soil fertilizer such as Miracle Gro or ZIPP

Procedures: 1. Gather materials. 2. Fill control bottle approximately 2/3 full with a mixture of common landfill materials: soil, paper, metal, plastic, glass, yard and food wastes, and water. 3. Fill one bottle 2/3 full with common landfill materials with no glass or plastic added. 4. Fill one bottle 2/3 full with common landfill materials with no added food wastes. 5. Fill one bottle 2/3 full with common landfill materials and add ¼ cup of common commercial yard fertilizer such as ZIPP or Miracle Gro. 6. Place a thermometer strip on each bottle to measure and maintain a constant temperature in each bottle. 7. Stretch one balloon over the top of each container. 8. Place containers around a centrally located heat source with thermometers placed away from source. 9. Maintain a constant heat source. Adjust position of experiment bottles to ensure equal temperature in each bottle. 10. Monitor balloons for expansion. Measure balloon diameters as they inflate over time.

Results: The test bottles were allowed to decompose under controlled heat from a 100 watt bulb. The balloons attached to the tops of the bottles expanded at various rates based on the amount of gases that were being produced within the bottles as the materials began the decomposition process. The landfill model which contained normal landfill materials with the exception of glass and plastic produced gases most rapidly. The landfill model which served as the control, and contained paper, plastics, metal, glass, food and yard wastes, and water (standard landfill materials) produced gases at the second most rapid rate. The landfill model which contained normal landfill materials with the addition of a commercial fertilizer produced gases third fastest. The landfill model which contained normal landfill materials without the addition of glass was next, and was followed by the model containing normal landfill materials with no added water.

Conclusions: The hypothesis was correct. The landfill model which contained a combination of paper, metal, organic matter found in food and yard wastes, and water produced landfill gases at the greatest rate. The experiment proves that landfills which do not allow plastics and glass would be able to provide potentially usable energy gases at a faster rate than landfills which allow plastics and glass—products that have a longer decomposition period. The landfill model which produced gases at the least rapid rate was the model which did not contain water. This leads to the conclusion that water is an essential material in the decomposition of landfill materials. Perhaps companies which specialize in converting landfill gases to usable energy sources will be able to use this information to determine the best materials to allow into the landfill. A company would want to limit the amount of plastics and glass in their landfills to get the most gases as quickly as possible.