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1 Plastivida Brazil June 10, 2008 Joseph P. Greene, Ph.D. Professor California State University, Chico Chico, CA 95929-0789 Biodegradable and Degradable.

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Presentation on theme: "1 Plastivida Brazil June 10, 2008 Joseph P. Greene, Ph.D. Professor California State University, Chico Chico, CA 95929-0789 Biodegradable and Degradable."— Presentation transcript:

1 1 Plastivida Brazil June 10, 2008 Joseph P. Greene, Ph.D. Professor California State University, Chico Chico, CA Biodegradable and Degradable Plastics Biodegradation Testing in Aerobic Compost and Anaerobic Environments

2 2 Agenda Research Objectives Products Tested Results –Compost Environment Chico Green Yard Waste Chico In-vessel Manure Waste Vacaville In-vessel Food Waste Mariposa County In-vessel Municipal Solid Waste (MSW) Laboratory ASTM D-6400 –Marine Water Environment –Anaerobic Digestion Environment –Laboratory Quality Tests for Contamination of Recycled Plastics Conclusions and Recommendations Questions

3 3 Objectives of Research Evaluate –Performance, degradation rates and environmental impacts of degradable plastic products in commercially operated compost facilities and in simulated marine environments. Testing –Bio-degradation Compost environment: windrow, in-vessel, and laboratory locations Marine environment Anaerobic digestion –Environmental Safety Assessments Fate and persistence of the by-products and toxicity resulting from the degradation –Mechanical and physical properties Recycled plastics with contamination from degradable plastics

4 4 What does Biodegradable Mean? Can the microorganisms in the disposal system (composting, soil, anaerobic vessel) assimilate/utilize the carbon substrate as food source completely and in a short defined time period? CO 2 + H 2 O + Cell biomass Complete microbial assimilation Specified time frame. No residual residues. Hydrolytic Polymer chains with susceptible linkages Enzymatic Oxidative Oligomers & polymer fragments Environment – soil, compost, waste water plant, marine Biodegradation: Only if all fragmented residues consumed by microorganisms as a food & energy source Define time and environment (disposal system) Reference: Dr. Ramani Narayan, Michigan State University,

5 5 Biodegradable versus Degradable Plastics Biodegradable Plastics –Degraded by microorganisms in soil, compost, or marine environments. –Made from natural materials, e.g.,corn, potato, polylactic acid, sugar cane, microbes, etc. –Made from petroleum products, e.g. modified or polyesters. –Compostable Regulated by ASTM standards- will degrade in compost environment in less than 180-days. Does not leave any fragments in residue, does not have any heavy metals or toxins, and will support plant life. Degradable plastics –Degraded by sunlight, oxygen, or microbes. Oxodegradable, photo-degradable, starch-polyethylene plastics. –Can cause environmental problems. Results in small fragments that can pollute compost, landfill, marine. Does not degrade as fast as compostable plastics, may leave small fragments in soil, may not have toxic residuals, may not support plant life.

6 6 Designing products to be degradable or partially biodegradable causes irreparable harm to the environment Degradable, biobased, single-use, disposable packaging and consumer plastics, and plastic-paper combination products (non-durable goods) have serious environmental consequences. Must ensure complete biodegradability in a short defined time frame (determined by the disposal infrastructure like composting) TIME --- ONE GROWING SEASON; MAYBE TWO DISPOSAL ENVIRONMENT – Composting, anaerobic digestion plants, marine/oceans, soil DEGRADABLE = Major Environmental Problems MUST ENSURE COMPLETE BIODEGRADABILITY IN THE SELECTED DISPOSAL ENVIRONMENT (as per ASTM test methods and specifications) Reference: Dr. Ramani Narayan, Michigan State University,

7 7 Definitions Degradable plastics –All plastics are degradable, though the mechanism is different. –Oxidation: plastics degrade in oxygen environment. Anti-oxidants are added to polymers. –UV light: plastics degrade in sunlight. Stabilizers are added to polymers. –Heat: polymers can degrade under high temperatures. Stabilizers are added Oxo-Degradable –Pro-degradents are added to increase the rate of oxidation and disintegration of plastics though NOT biodegradable since microorganisms do not consume them. Biodegradable –Plastics degrade from microorganisms that consume material but time frame is not specified. Can be biobased or petroleum based. Both can be consumed by microorganisms. Compostable (Most complete definition) –Plastics that degrade from microorganisms that consume material in specified time frame and under specified environmental conditions. Can be biobased or petroleum based. Both can be consumed by microorganisms.

8 8 Products Tested Compostable (Certified by Biodegradable Polymers Institute- BPI) –PLA Cups, forks, spoons, knives, clamshell containers, lids, and straws –Biobag trash bags –Ecoflex Polyester bags –PHA Bags –Husky Eco Guard biodegradable bags –Sugar Cane Bagasse plates, bowls, and containers. Oxo-Degradable (NOT certified by Biodegradable Polymers Institute- BPI) –Natural Value Oxo-degradable Ecosafe Trash Bags –Oxo Biodegradable Eco-friendly plastic bag –UV-degradable plastic bags and soda can rings Control –LDPE plastic trash bag –Kraft paper –Cellulose filter paper

9 9 Commercial Compost Environment Sites –Chico Green Yard Waste –Chico In-vessel Manure Waste –Vacaville In-vessel Food Waste –Mariposa County In-vessel Municipal Solid Waste 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.

10 10 Chico Green Yard Waste Compost Pictures (120 days) OxobiodegradableCompost pile PLA ContainerBiobag bag Incoming trash

11 11 Chico Green Yard Waste Compost Results: –30 days: (Windrow) No degradation: Oxo-biodegradable plastic trash bags Some degradation: Food waste and PLA cups, forks, spoons, knives, clamshell containers, lids, and straws, Sugar cane plates and lids, and Biobag trash bags. –120 days: (Windrow) No degradation: Oxo-biodegradable plastic trash bags More degradation: Small fragments of PLA container and straw, and Biobag trash bags. Full degradation: no visible fragments- PLA cups, forks, spoons, knives, and lids; sugar cane lids and plates.

12 12 In-vessel Manure and Food Waste Compost Pictures (120 days) In-vessel Compost pile PLA ContainerBiobag bag Incoming MSW trash Turning row

13 13 In-vessel Manure and 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. –120 days: (Windrow) More degradation: Small fragments of PLA cups and container, and Biobag trash bags. Full degradation: no visible fragments- PLA, forks, spoons, knives, and lids; sugar cane lids and plates.

14 14 NorCal Vacaville In-vessel Compost Pictures Compost pile after 30 days In-vessel composting with polyethylene cover

15 15 NorCal In-vessel Compost Pictures Oxodegradable plastic bag UV-polyethylene plastic bag Mirel PHA plastic bagCorn starch plastic bagEcoflex plastic bag

16 16 NorCal Vacaville In-vessel Compost Pictures PLA lidsSugar can lids Husky Eco-Guard plastic bagLDPE plastic bags Kraft paper

17 17 NorCal Vacaville In-vessel Compost Pictures Compost pile after 30 days Burlap sacks filled with samples

18 18 NorCal Vacaville In-vessel Food Waste Compost Results –30 days (In-vessel) September to October 2006 Some degradation: Food waste and PLA cups, forks, spoons, knives, clamshell containers, lids, and straws, Sugar cane plates and lids, and Corn starch trash bags.

19 19 NorCal In-vessel Compost Pictures- 30 days Oxodegradable plastic bag UV-polyethylene plastic bag Mirel PHA plastic bagCorn starch plastic bagEcoflex plastic bag

20 20 NorCal Vacaville after 30 days Pictures PLA lidsSugar can lids Husky Eco-Guard plastic bagLDPE plastic bags Kraft paper

21 21 Vacaville In-vessel Food Waste Compost Pictures (180 days) In-vessel Compost pile Sugar cane lidsKraft paper Compost temperature: 140 +/- 5  F Moisture: 40-45%

22 22 Vacaville In-vessel Food Waste Compost Pictures (180 days) Oxodegradable bagUV-degradableLDPE stretch film control

23 23 Vacaville In-vessel Food Waste Compost Results –30 days (In-vessel) –60 days: (Windrow) –180 days: (Windrow) March 2007 No degradation: Oxo-biodegradable and UV degradable plastic trash bags; LDPE control. Some bio-degradation: Sugar cane lids and Kraft paper control though samples were very wet and fell apart when moved. Full degradation: no visible fragments- PHA bag, Ecoflex bag, PLA lids, Biobag trash bags.

24 24 Mariposa County In-vessel MSW Compost Pictures ECS In-vessel Compost MethodInside chamber with samples

25 25 Mariposa In-vessel Food Waste Compost –Oven Temperature: 60  C for 3 days, 50  C for 21 days –% Moisture: > 50%

26 26 Mariposa after 42 days Pictures Oxodegradable plastic bag UV-polyethylene plastic bag Mirel PHA plastic bagCorn starch plastic bagEcoflex plastic bag

27 27 Mariposa after 42 days Pictures PLA lidsSugar can lids Husky Eco-Guard plastic bagLDPE plastic bags Kraft paper

28 28 NorCal Vacaville Windrow Compost In-vessel Compost pile Compost temperature: 140 +/- 5  F Moisture: 40-45% Samples moved to windrow compost after 42 days for an additional 150 days

29 29 Mariposa In-vessel Food Waste Compost Results –42 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. –150 days: (Windrow) Identical to Vacaville result No degradation: Oxo-biodegradable and UV degradable plastic trash bags; LDPE control. Some bio-degradation: Sugar cane lids and Kraft paper control though samples were very wet and fell apart when moved. Full degradation: no visible fragments- PHA bag, Ecoflex bag, PLA lids, Biobag trash bags.

30 30 Mariposa In-vessel (42 days) plus Vacaville Windrow Compost (150 days) Pictures Note: Same results as Vacaville Compost alone Oxodegradable bagsKraft paper and sugar cane lids

31 31 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 CO 2 measurement with LabView data acquisition system and computer control. CO 2 scrubber, 50 psi pressure canister to supply moist air. –45-day test interval Tests –Monitored carbon dioxide and oxygen levels for 45-days. –Phytoxicity tests with tomato seeds. –Regulated metals testing for Cd, Pb, and Co.

32 32 Testing Methods Laboratory Environment –ASTM 5338 Standards Sampling process schematic. Wet air void of CO 2 Computer CO 2 or O 2 Detector Biogas 42 Jars at 50C for 45 days

33 33 Laboratory Biodegradation Compost Pictures

34 34 45-day Degradation Results MaterialBiodegradation Conversion % Degradation rate g/day Results Cellulose positive control Pass Kraft paper positive control Pass PHA bag Pass PLA straws Pass Sugar cane plate Pass Biobag trash bag Pass Ecoflex bag Pass Blank compost control Polyethylene negative control Fail Oxodegradable bag Fail

35 35 Plant Growth Results MaterialAverage Germination % Average Length, mm after 10- days Average Germination Index Average pHResults Compost control Pass Cellulose control Pass Avicell cellulose control Pass Kraft paper control Pass Polyethylene negative control Pass PLA Container Pass Sugar Cane lid Pass Biobag trash bag Pass PHA bag Pass Ecoflex bag Pass Oxo-degradable bag Pass

36 36 Regulated Metal Testing Note: Maximum limit of Pb is 30 mg/kg, Cd is 17 mg/kg and Co is not regulated in the US. Material Average Lead ConcentrationResult Average Cd ConcentrationResult Compost 0.02 mg/kgPass.001 mg/kgPass Cellulose 0.02 mg/kgPass.001 mg/kgPass Kraft Paper 0.02 mg/kgPass.001 mg/kgPass Polyethylene 0.02 mg/kgPass.001 mg/kgPass Biobag 0.02 mg/kgPass.001 mg/kgPass PLA straws 0.02 mg/kgPass.001 mg/kgPass Sugar Cane 0.02 mg/kgPass.001 mg/kgPass Ecoflex bag 0.02 mg/kgPass.001 mg/kgPass PHA bag 0.02 mg/kgPass.001 mg/kgPass

37 37 Anaerobic Digestion at UC Davis Materials –Kraft paper and low density polyethylene controls –Oxo-biodegradable: Ecosafe and Eco-friendly plastic trash bags –Biodegradable: Food waste and biodegradable products, i.e., PLA lids and straws, Biobag trash bags, PHA bags, Ecoflex bags, and Stalk Market sugarcane lids. Methods –Per Dr. Zhang’s research from U.C. Davis –Place 1 g of sample in 1-L jar with 0.5L of water waste and food sludge at 50°C. –Duplicate test with new samples. Tests –Monitor biogas production over 30 day period. More research is needed.

38 38 Anaerobic Digestion at UC Davis Pictures

39 39 Anaerobic Digestion at UC Davis Results: Duplicate trial: 45 days Conclusions –Digestion occurs and biogas (CO 2 and Methane) is generated for first 15 days. –PHA DOES continues to generate biogas and thus digest anaerobically for the next 30 days. –PLA, Ecoflex, oxo-degradable, UV-degradable, and Kraft paper DO NOT generate biogas after 15 days.

40 40 Laboratory Marine Testing Materials –Kraft paper and low density polyethylene controls –Oxo-biodegradable: Ecosafe and Eco-friendly plastic trash bags –Biodegradable: Biodegradable products, i.e., PLA straws, Biobag trash bags, PHA bags, Ecoflex bags, and Stalk Market sugarcane lids. Methods (Based on ASTM D-6692 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 and place in oven. –At 60 days weigh samples after 24 hours of drying in air and then add fresh 40 ml and place in oven. –At 90 days weigh samples after 24 hours of drying in air. More research is needed.

41 41 Laboratory Marine Testing Pictures Experimental Set-upOxo-degradable 90 days PHA 30 days PHA 90 days

42 42 Laboratory Marine Testing Results –30 days in water No degradation: Oxo-biodegradable and UV degradable plastic trash bags; LDPE control, Kraft paper control; PLA lids; Sugar cane lids; Biobag trash bags; Ecoflex bag, UV degradable soda rings. Some degradation: PHA bag- 36% disintegration –60 days in water No degradation: Oxo-biodegradable and UV degradable plastic trash bags; LDPE control, Kraft paper control; PLA lids; Sugar cane lids; Biobag trash bags; Ecoflex bag, UV degradable soda rings. Some degradation: PHA bag- 60% disintegration –90 days: No degradation: Oxo-biodegradable and UV degradable plastic trash bags; LDPE control, Kraft paper control; PLA lids; Sugar cane lids; Biobag trash bags; Ecoflex bag, UV degradable soda rings. Some degradation: PHA bag- 70% disintegration

43 43 Laboratory Quality Tests for Contamination of Recycled Plastics Materials –Recycled PET, HDPE, LDPE –Oxo-biodegradable plastic trash bags –Biodegradable: PLA straws and Biobag trash bags Method –Combine LDPE and Biobag bags at 0%, 10% and 20%. –Combine HDPE and PLA at 0%, 5%, and10%. –Heated plastic bags under IR heater and then chopped with grinder. –Injection molded samples with dry blend of plastic.

44 44 Laboratory Quality Tests for Contamination of Recycled Plastics Processing –Injection molding tensile bars with 55 ton Arburg. –Blow molding of bottles with Rocheleau R4 machine. –Blown film with 1” Braybender extruder. Testing –Quality Melt index, density, moisture % Opacity, dart impact –Mechanical properties Tensile modulus, elongation, and strength, impact –Samples were tested in batches of 5.

45 45 Results Contamination of Recycled Plastics Quality tests –PLA plastics at concentrations of 5 and 10 wt% Negatively affected melt index, moisture content of LDPE. Decreased tensile strength and impact strength of LDPE. –Corn-starch based plastic bags at concentrations of 10 and 20 wt% Negatively affected melt index, moisture content of HDPE. Decreased tensile strength and impact strength of HDPE. –Oxodegradable plastics at concentrations of 10 and 20 wt% Negatively affected melt index, moisture content of LDPE. Decreased tensile strength and impact strength of LDPE. –More research is needed.

46 46 Results Contamination of Recycled Plastics Mechanical tests Material Tensile strength Ultimate Elongation Tensile Modulus Impact strength % increase LDPE- neat-- LDPE 10%oxo LDPE 20% oxo LDPE 10% biobag LDPE 20% biobag HDPE- neat-- HDPE 5% PLA HDPE 10% PLA

47 47 Summary of Biodegradation Results Environment Compostable Plastics Oxodegradable PlasticsPolyethylene Meet ASTM D standards Compost (with proper moisture, oxygen, and temperature levels) Yes- 100% biodegradable in 180 days No Landfill (with low moisture, oxygen, and temperature levels) No Marine (with high moisture levels and low oxygen and temperature levels) No, for most Yes, for PHANo Anaerobic Digester (with high moisture levels and low oxygen and temperature levels) No, for most Yes, for PHA No

48 48 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 Green yard waste, In-vessel compost systems, and Laboratory conditions Oxodegradable and UV-degradable plastics do NOT biodegrade in any compost environments. Oxodegradable and UV-degradable plastics may fragment into smaller pieces compost environments, but may also create more SEVERE environmental consequences.

49 49 Conclusions PHA degraded in marine and anaerobic digestion environments. Sugar cane degraded in anaerobic digestion environment and also in marine environment. PLA straws, Ecoflex bag, and Biobag did not disintegrate in marine environment and biodegraded slowly in anaerobic digestion environment.

50 50 Conclusions Biodegradable plastics are a contaminant to recycled plastics. –PLA and Biobag plastics at concentrations of 10 and 20 wt% can negatively impact melt index, moisture content, tensile and impact properties. –Contamination of biodegradable plastics can be controlled like other contaminants to recycled plastics.

51 51 Recommendations The research work will help the expanded use of compostable plastic materials for selected applications. The compostable materials should be certified as compostable by BPI and included in procurement standards. The compostable plastic materials should perform well in simple applications, e.g., food service ware, lawn and leaf refuse bags that have dry contents, grocery bags, department store bags, and pet bag products.

52 52 Acknowledgements The author would like to thank the following people and organizations who have helped develop this research work: –California Integrated Waste Management Board –Mr. Edgar Rojas (CIWMB) and Mr. Mike Leaon (CIWMB) –Dr. Cindy Daley (CSU, Chico), Dr. Ken Derucher (CSU, Chico), Dr. Gregory Kallio (CSU, Chico), Dr. Randy Miller (CSU, Chico), and Mr. Peter Natale (CSU, Chico) –Dr. Fengyn Wang (NorCal Waste Systems), Chris Taylor (NorCal Waste Systems), and Mr. Greg Pryror (Jepson Prairie Organics). –Mr. Steve Engfer (Mariposa County Waste Management).

53 53 Questions?


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