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Biopolymers and BioPlastics Conference San Francisco, CA

A Review of Biodegradation of Biodegradable Plastics under Industrial Compost, Marine, Soil, and Anaerobic Digestion. Biopolymers and BioPlastics Conference San Francisco, CA. October 20, 2017 Joseph P. Greene, Ph.D. Professor California State University, Chico Chico , CA  95929-0789. Topics .

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Biopolymers and BioPlastics Conference San Francisco, CA

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  1. A Review of Biodegradation of Biodegradable Plastics under Industrial Compost, Marine, Soil, and Anaerobic Digestion Biopolymers and BioPlastics ConferenceSan Francisco, CA October 20, 2017 Joseph P. Greene, Ph.D.ProfessorCalifornia State University, ChicoChico, CA  95929-0789

  2. Topics • Introduction to California State University, Chico • Biodegradation ASTM Standards • Biodegradable, Oxodegradable, and UV-degradable Plastic Materials • Biodegradation Testing Results • Hot Industrial Compost Lab and Field Environments • Marine Water Lab Environment • Soil Lab Environment • Anaerobic Digestion Lab Environment (Landfill) • Conclusions and Recommendations • Questions

  3. Introduction • California State University, Chico • 17,600 students • One of 23 Cal State Universities in CA • Located 90 miles north of Sacramento, CA • Department of Mechanical and Mechatronic Engineering and Sustainable Manufacturing. • 758 students in fall 2017 • Dr. Joseph Greene, Department chair and professor in Sustainable Manufacturing Program. • Ph.D. in Chemical Engineering from the University of Michigan. • Professor for 19 years at Chico State University. • Senior manufacturing and development engineer at General Motors Company in Warren, Michigan for 14 years.

  4. Background • Plastics laboratory at Chico State • Three Arburg electric injection molding machines • Brabender blown film extruder • Leistritz twin screw extruder 19mm and 45 L/D • Blow film extruder • 100-ton compression molder • Rotational molder • Thermoformer • Biodegradation testing per ASTM standards • Plastic quality and mechanical testing

  5. ASTM Biodegradation Tests • Biodegradation of plastics can be evaluated with a two-step process per ASTM standards. • Step 1. Approved test method • Assures that the biodegradation test follows approved approved procedures to generate valid results. • ASTM test methods for biodegradation: • D5338. Test method for hot industrial compost • D6691. Test method for cool marine conditions • D5511. Test method for anaerobic digestion conditions • D5526. Test method for accelerated landfill conditions • Step 2. Certification of biodegradation • ASTM 6400. Certification of biodegradation for industrial compost. • ASTM 7081. Certification of biodegradation for marine conditions. *Note: ASTM does not have a method for certification of soil or landfill biodegradation. **Note: Good reference for explanation of ASTM standards: Sustainable Plastics by Joseph Greene PC

  6. Biobased and Biodegradable Plastics • Biobased plastics are plastics made from natural materials • PLA, PHA, ecoflex, starch-based plastics, sugar cane plastics, cellulose, others. • http://bpiworld.org/ provides as good description of each of the certified biodegradable plastics. • These biodegradable plastics were tested in the following environments: • Hot industrial compost. • Cool marine water. • Cool soil from national forests. • Cool anaerobic digestion to simulate landfill conditions.

  7. Biodegradation in Industrial Compost Environment

  8. Industrial Compost Environment • What happens to plastics in commercial compost? • Site: Nor-Cal in-vessel food waste industrial compost facility in Dixon,CA • Materials (Purchased at stores or on-line) • Compostable:PLA lids, Biobag trash bags, Ecoflex Polyester bags, PHA Bags, Husky Eco Guard biodegradable bags, Sugar Cane Bagasse lids. • Oxodegradable: Ecosafe Trash Bags, Eco-friendly plastic bag, UV-degradable plastic bags • Controls: LDPE plastic trash bag and Kraft paper • Tests • Monitored visual disintegration and biodegradation of products after 30, 60, 90, and 180 day test intervals. • Monitored temperature of air and compost, moisture percentage, pH, compost maturity, and % solids.

  9. NorCal In-vessel Compost Pictures Corn starch TPS plastic bag Mirel PHA plastic bag PLA lids Sugar can lids Oxodegradable plastic bag LDPE plastic bags

  10. NorCal Vacaville In-vessel Food Waste Compost • Results • 30 days (In-vessel) • Some degradation: Food waste and PLA cups, forks, spoons, knives, clamshell containers, lids, and straws, Sugar cane plates and lids, and Biobag trash bags. • 180 days: (Windrow) • Full disintegration: no visible fragments- PHA bag, Ecoflex bag, PLA lids, Husky Eco-Guard TPS plastic trash bags. • Some high disintegration: Sugar cane lids and Kraft paper control • No disintegration: Oxo-biodegradable and UV degradable plastic trash bags; LDPE control.

  11. NorCalVacaville In-vessel Food Waste Compost Pictures (180 days)(Note: Kraft paper fragments were wet and had low strength and obvious lignin degradation) Static Compost pile Kraft paper Sugar cane lids Compost temperature: 140 +/- 5F Moisture: 40-45%

  12. NorCal Vacaville In-vessel Compost and Vacaville Static Pile Compost (180 days) Oxodegradable bags 180 days Note: Oxo-degradable plastics are not designed to biodegrade in a compost environment.

  13. Laboratory Biodegradation Compost • Materials • Kraft paper, Cellulose filter paper and low density polyethylene controls • Oxo-biodegradable: Ecosafe and Eco-friendly plastic trash bags • Compostable biodegradable products, i.e., PLA straws, Biobag trash bags, PHA bags, Ecoflex bags • Biodegradable: Stalk Market sugarcane lids. • Method (Per ASTM D-5338) • Redesigned of laboratory procedure with • Improve the accuracy of CO2 measurement with LabView data acquisition system and computer control. • CO2 scrubber, 50 psi pressure canister to supply moist air. • 180-day test interval • Tests • Monitored carbon dioxide and oxygen levels for 180 days. • Phytoxicity tests with tomato seeds. • Regulated metals testing for Cd, Pb, and Co.

  14. Aerobic Industrial CompostTests per ASTM 5538 Test Method • What happens to plastic materials in an anaerobic environment? • Method • Test must be run per test conditions from ASTM 5538 test method • Testing that maintains a temperature 58°C. • 100 g of plastic with 600 g of mature compost. • Measure carbon dioxide over 6 months. • Calculate % biodegradation from the grams of carbon emitted as a gas divided by the grams of carbon in the plastic sample. • Biodegradation standards are better explained in the following book. • Reference: J. Greene, Sustainable Plastics: Environmental Assessments of Biobased, Biodegradable, and Recycled Plastics, Wiley, Hoboken, NJ, ISBN: 978-1-118-10481-1(July 2014)

  15. Computer CO2 or O2 Detector Wet air void of CO2 Biogas Testing Methods • Laboratory Environment • ASTM 5338 Standards Sampling process schematic.

  16. Fail Fail Pass Laboratory Biodegradation Compost Results Pass

  17. Industrial Compost Biodegradation Tests • Step 2. Approved biodegradation specification • Industrial compost environment per ASTM D6400 • ASTM 6400 • Test must be run per test conditions from ASTM 5338 • Testing that maintains a temperature 58°C. • 100 g of plastic with 600 g of mature compost. • Measure carbon dioxide over 6 months. • Calculate % biodegradation from the grams of carbon emitted as a gas divided by the grams of carbon in the plastic sample. • Biodegradation standards reports that the plastic sample must exhibit 90% biodegradation after 6 months of testing. PC

  18. 180-day Degradation Results

  19. Biodegradation in Marine Environment

  20. Plastic Waste in the Ocean • Ocean Plastic Debris • Plastics comprise 60 to 80% of plastic debris. • 80% of ocean debris has a land source. • Pacific Gyre • Dead zone off of CA has floating debris, the size of Texas. • Debris is eaten by birds, mammals, and fish causing injury and death. Top Ten USA Marine Debris Items in 2008 Reference: Ocean Conservancy's International Coastal Cleanup program

  21. Laboratory Marine Testing • Materials • Microcellulose powder and low density polyethylene controls • Biodegradable: Biodegradable products, i.e., PLA straws and PHA bags • Methods (Based on ASTM D-6691 standards) • Place 30 mg of sample in jar with 100 ml of ocean water at 30°C. • Ocean water was retrieved in July 2007 from Big Sur beach in California. • Water was held at 5°C until testing. • Tests • At 30 days weigh samples after 24 hours of drying in air and then replace water with fresh 100 ml ocean water and place in oven. • At 60 days weigh samples after 24 hours of drying in air and then add fresh 40 ml ocean water and place in oven. • At 90 days weigh samples after 24 hours of drying in air.

  22. Laboratory Marine TestingPictures Experimental Set-up Oxo-degradable 90 days PHA 90 days PHA 30 days

  23. Aerobic Marine BiodegradationTests per ASTM 6691 Test Method • What happens to plastic materials in an anaerobic environment? • Method • Test must be run per test conditions from modified ASTM 6691 test method. • Testing that maintains a temperature 30°C. • 1g of plastic with 40 ml of ocean water and 100 g of sand and sediment. • Measure carbon dioxide over 6 months. • Calculate % biodegradation from the grams of carbon emitted as a gas divided by the grams of carbon in the plastic sample. • Reference: J. Greene, Sustainable Plastics: Environmental Assessments of Biobased, Biodegradable, and Recycled Plastics, Wiley, Hoboken, NJ, ISBN: 978-1-118-10481-1(July 2014)

  24. Biodegradation Tests • Step 2. Approved biodegradation specification • ASTM 7081 • Test must be run per test conditions from modified ASTM 6691 test method • The carbon must be converted from the plastic sample to carbon dioxide as measured by a respirometer or by titration experiments. • Measure carbon dioxide over 6 months. • Calculate % biodegradation from the grams of carbon emitted as a gas divided by the grams of carbon in the plastic sample. • Biodegradation standards REQUIRES that the plastic sample must exhibit greater than 30% biodegradation after • 6 months of testing. PHA PHA PASS Cellulose Fail Polyethylene PLA PC

  25. Laboratory Marine Testing Results • Results • After 180 days: • PHA bag- 38 and 48% biodegradation- PASS • Cellulose powder- 32% biodegradation- PASS • PLA lids- No biodegradation- FAIL • Polyethylene- No biodegradation- FAIL

  26. Biodegradation in Soil Environment

  27. Soil Environment Soil biodegradation tests per modified ASTM 5538 test method • What happens to plastic materials in a soil environment? • Method • Test must be run per test conditions from ASTM 5338 test method. • Testing that maintains a temperature 40°C. • 100 g of plastic with 600 g of mature compost. • Measure carbon dioxide over 6 months. • Calculate % biodegradation from the grams of carbon emitted as a gas divided by the grams of carbon in the plastic sample. • Biodegradation standards do not exist in the US for soil biodegradation

  28. Results after 15 and 20 weeks: some disintegration in starch plastics, paper, and polyethylene plastics.

  29. Aerobic Soil Laboratory Tests per Modified ASTM 5538 Test Method • What happens to plastic materials in an anaerobic soil environment? • Method • Test must be run per test conditions from ASTM 5538 • Testing that maintains a temperature 40°C. • 100 g of plastic with 600 g of mature compost. • Measure carbon dioxide over 6 months. • Calculate % biodegradation from the grams of carbon emitted as a gas divided by the grams of carbon in the plastic sample. • Note: There are ASTM test standards for soil biodegradation. • Reference: J. Greene, Sustainable Plastics: Environmental Assessments of Biobased, Biodegradable, and Recycled Plastics, Wiley, Hoboken, NJ, ISBN: 978-1-118-10481-1(July 2014)

  30. Soil biodegradation laboratory results after 172 days • Test 3. Biodegradation Test Results • Paper experienced approximately 38% biodegradation. • Dry starch-based plastics experienced approximately 36% biodegradation. • Wet starch-based plastics that were soaked for two hours in fresh creek water experienced approximately 28% biodegradation. • Polyethylene plastics experienced less than 5% biodegradation. Paper Starch dry Starch wet Polyethylene

  31. Biodegradation in Anaerobic Environment

  32. Anaerobic Digestion Testing • What happens to organic materials in landfill environment? • Do they biodegrade? • Old Landfills: • Anaerobic environment in a landfill can be simulated with anaerobic digestion. • Inactive landfill- no oxygen, low temperature, and no water results in no organic microbes • Airless tomb for materials per US EPA (1991) • Results • Materials are not designed to biodegrade in landfill. • Landfill is not designed to biodegrade organic materials due to lack of oxygen and moisture and temperature.

  33. Landfill Environment • Old Landfills: Inactive landfill- no oxygen, low temperature, and no water results in no organic microbes • Airless tomb for materials per US EPA (1991) • Contents of typical landfill • ~ 30% organic • ~ 20% paper • ~ 10% lumber • ~ 10% plastic • ~ 30% metal, glass, other materials • Results • Plastics and organics do not biodegrade in a landfill.

  34. Anaerobic Digestion Tests per Modified ASTM 5511 Test Method • What happens to plastic materials in an anaerobic environment? • Method • Test must be run per test conditions from ASTM 5511 • Testing that maintains a temperature 37°C in 2.5 L jars. • 4 g of plastic per liter of inoculum • Inoculum (pH = 7.76; FOS = 1.08g/L; TAC = 6.49g/L was stored one week at 37°C before the beginning of the experiment to let it degas. • Measure volume of biogas (methane and carbon dioxide) over 20 days. • Measured percentage of each gas with a Gas Chromatograph. • Calculate % biodegradation from the grams of carbon emitted as a gas divided by the grams of carbon in the plastic sample. • Biodegradation standards do not exist in the US for anaerobic digestion environment

  35. Anaerobic Digestion Test Results • Experimental setup • Plastic is placed in liquid inoculum at 37°C. • The biogas generated pushes out water in a column to measure volume of gas. • Biogas is withdrawn for gas sampling and the concentration is measured with a GC.

  36. Anaerobic Digestion Test Results • The test results • PHA had 100% biodegradation in 14 days. • Cellulose control had 40% biodegradation after 4 days • Polyethylene had 0% biodegradation after 20 days.

  37. Conclusions • Compostable materials degrade under commercial compost environments. • PLA container, Sugar cane lids, PHA bag, Ecoflex bag, and Husky Eco-Guard plastic bag completely degraded in commercial • In-vessel food waste compost systems and • Laboratory conditions • Oxodegradable plastics do NOT biodegrade in compost environments. • Oxodegradable plastics may fragment into smaller pieces in compost environments, but may also create more SEVERE environmental consequences.

  38. Conclusions • PHA disintegrated significantly in marine environment after 180 days. • PLA straws, Ecoflex bag, and Biobag did not disintegrate in marine environment after 90 days. • PHA plastic bags and cellulose powder biodegraded over 30% in 180 days. • PLA plastic film and polyethylene plastic film did not biodegrade in the marine environment after 180 days. • Oxodegradable and UV-degradable plastics did not disintegrate in marine environment after 90 days. • Starch-based plastics biodegraded over 40% in a simulated soil burial laboratory environment. • PHA and cellulose powder biodegraded in a cool anaerobic digestion environment. • Polyethylene plastic did not biodegrade in a cool anaerobic digestion environment.

  39. Acknowledgements • The author would like to thank the following people and organizations who have helped develop this research work: • Dr. Jim Hill, California CALRecycle Organization • Dr. Cindy Daley (CSU, Chico), Dr. Ken Derucher (CSU, Chico), Dr. Gregory Kallio (CSU, Chico), Dr. Randy Miller (CSU, Chico), and Mr. Chad Nevin, Mr. Jeremie Vuong, Mr. Gabirel Magny (CSU, Chico) • Dr. Fengyn Wang (NorCal Waste Systems), Chris Taylor (NorCal Waste Systems), and Mr. Greg Pryror (Jepson Prairie Organics).

  40. Questions?

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