Effects of Compost Material on Various Degradable Lawn Bags

1. Effects of Compost Material on Various Degradable Lawn Bags Joe Mautino 9th Grade Central Catholic High School

2. Problem • Plastic bags are used frequently and add to pollution problems • Plastic bags are not thought to readily decompose • Composting has been implied as an effective means of recycling organic materials • Can composting degrade plastic bags as readily as paper?

3. Background (Composting) • Composting is the transformation of organic waste into compost • Main components of composting • Organic matter • Brown (leaves, twigs, manure) supply Carbon • Green (grass, fruit rinds) supply Nitrogen • Bacteria • Mesophilic Bacteria Range (10 C° - 40 C° ) • Thermophilic Bacteria Range (40 C° - 65 C°) most desirable • Oxygen • Oxygen is used up quickly by the microbes as they metabolize the organic matter • Less oxygen, slower composting • Moisture • Ideal range is 40% to 60% moisture • High moisture causes anaerobic conditions, low moisture inhibits activity

4. Background (Plastic) Americans throw away approximately 100 billion polyethylene plastic bags a year Made from crude oil Accounts for 4% of the worlds total oil usage The process of making plastic bags requires large amounts of electricity Does not readily decompose

5. Background (Paper) Paper production impacts the environment in many ways • Collection of timber for production is long and environmentally taxing • Water usage • Thousands of gallons of clean H2O used to wash and bleach pulp • Paper = 1 part pulp to 400 part H2O Disposition of used paper • Landfills • Takes many years to decompose • Recycle • Requires extensive process to return to pulp

6. Background (BioPlastic) • New biodegradable & compostable plastics derived from cornstarch, Mater-Bi • Made from starch, biodegradable polyester, other natural plasticizers • Claim to biodegrade in 10-45 days • Biodegradable: degrade from composting into carbon dioxide, water, and inorganic biomass • Compostable: Meets ASTM -6400-99 • Biodegradable • Disintegrate • Low eco-toxicity

7. Purpose To determine the garbage bag that will decompose the most rapidly in a compost pile.

8. Hypothesis In the test compost, Mater-Bi plastic bags will decompose more than polyethylene plastic bags. The paper bags will undergo the greatest degree of decomposition. Null: No significant variation in decomposition rate will be composted between Mater-Bi, polyethylene plastic and paper.

9. 10 Mater-Bi plastic 127 mm * 127 mm bag pieces 10 polyethylene plastic 127 mm * 127 mm bag pieces 10 paper 127 mm * 127 mm bag pieces Digital scale (.000) grams 5 L of organic potting mix 15 L of cut grass 900 ml of cheese 500 ml of yogurt 500 ml of cucumber 700 ml of green pepper 400 ml of broccoli 1 22 L metal bucket A small electric heater 1 155 L insulated bucket 1 measuring cup Appropriate PPE Materials

10. Procedure • Collected and used appropriate PPE • Cut 10 127 mm * 127 mm pieces of each bag (Polyethylene plastic, Paper, and Mater-Bi plastic bags) • Weighed each sample and recorded initial mass of each piece • Created compost mixture with the organic materials (Approximately 20 L) • Placed the compost into a 22L bucket. • Mixed all 30 samples (Plastic, paper, and Mater-Bi plastic) into the compost mixture • Used a small heater under the bucket and set to 25°C

11. Procedure • Covered the small bucket with the 155L insulated can to keep a constant temperature • Used a small shovel to mix compost weekly • After 4 weeks removed sample bags from the compost • Cleaned bag samples by brushing all excess dirt from bags • Let the samples dry overnight • Weighed final mass

12. Polyethylene Plastic Experiment Samples (Control) Before After

13. Paper Experiment Samples Before After

14. Mater-Bi Plastic Experiment Samples Before After

15. Data

16. Anova Single Factor calculations for the Average Weight Loss For the 3 Bag Types

17. Percentage Weight Loss for the Average of Each Sample Bag

18. Observations • All elements in the compost biodegraded to rich black soil • Mater-Bi plastic showed indications that decomposition had started • The Polyethyleneplastic did not show any signs of biodegradation • Only little pieces of the paper bags were left

19. Future Improvements • Fill actual bags with organic material • Improve final cleaning to reduce residual compost on the samples • Add additional composting bacteria to accelerate decomposition

20. Conclusion • My alternate hypothesis was proven correct, that in the test compost, Mater-Bi plastic bags will decompose more than polyethylene plastic bags. The paper bags will undergo the greatest degree of decomposition. • My null hypothesis was rejected, shown by the P value stated in the Anova calculations.