Ramani Narayan, Michigan State University UNDERSTANDING BIODEGRADABILITY ROLE IN PLASTICULTURE MYTHS...
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Transcript of Ramani Narayan, Michigan State University UNDERSTANDING BIODEGRADABILITY ROLE IN PLASTICULTURE MYTHS...
Ramani Narayan, Michigan State University
UNDERSTANDING BIODEGRADABILITYROLE IN PLASTICULTURE
MYTHS & REALITY
Ramani NarayanUniversity Distinguished Professor
MICHIGAN STATE UNIVERSITY
If you use any of the slides/materials, please reference authorship and affiliation (Ramani Narayan, Michigan State University) – thank you
Copyright Ramani Narayan
&MATERIALS SCIENCE
Ramani Narayan, Michigan State University
PLASTICULTURE TECHNOLOGY
plastic mulch is standard practice used in agriculture to control weeds, increase crop yield, and shorten time to harvest
contributes significantly to the economic viability of farmers
Disposal is an issue – contributes to cost, and impacts on the environment
SOLUTION
DEGRADABILITY AND BIODEGRADABILITY DEGRADABILITY
Ramani Narayan, Michigan State University
The “VALUE PROPOSITION” FOR USING BIORESINS (BIOBASED AND OR BIODEGRADALBE)
• Using biodegradability as an end-of-life option to completely remove single use short life disposable plastics from the environmental compartment in a safe and efficacious manner via microbial assimilation
• Degradable, partial biodegradable not acceptable – serious health and environmental consequences
• Disposal environment (like composting, anaerobic digestor, marine
• Time to complete biodegradation
• Using bio/renewable feedstock (as opposed to petro/fossil feedstock:
• Reduces our carbon footprint and moves us to zero carbon or carbon neutral footprint
• Reduce CO2 emissions --- global warming climate change
• Provides a positive environmental footprint/profile (document using LCA tools)
Ramani Narayan, Michigan State University
TERMINOLOGY
BIOBASED (RENEWABLE)
Organic material containing in whole or part biogenic (biological sources) carbon
Refers to using biomass or crop feedstock (New carbon) vs petroleum or fossil feedstock (Old carbon)
Reducing carbon footprint
BIODEGRADABILITY – END-OF-LIFE option • functional property attribute to be designed and engineered into a biobased product
when needed or necessary!! • need to identify the (end-of-life)disposal system like composting, anaerobic digestion,
marine, soil • using microbes to completely utilize the carbon substrate and removing it from the
environmental compartment • Time to complete microbial utilization – no residue remaining
BIOMATERIALS -- Biomedical applications
Refers to:
Any material (metal, plastic, ceramic) implanted in the body -- design and engineering considerations different; biodegradability considerations different
Ramani Narayan, Michigan State University
TERMINOLOGY
Biobased plastics or productsOrganic material(s) containing in whole or part
biogenic carbon -- carbon from contemporary (non-fossil) biological sources – NEW CARBON
CO2 + H2O (CH2O)x + O2
Organic material(s) – IUPAC terminologyMaterial(s) containing carbon based compound(s) in whichthe carbon is attached to other carbon atom(s), hydrogen, oxygen, or other elements in a chain, ring, or three dimensional structure
Thus, to be classified biobased or biomass based, or renewable , the material must be organic and contain biogenic carbon (from biological sources)
Ramani Narayan, Michigan State University
Terminology (Contd)
BIOBASED
OR
BIOMASS BASED
OR
RENEWABLLY SOURCED
PLASTICS OR PRODUCTS
NOT BIODEGRADABLE
BIODEGRADABLE (Complete)
Petro based not biobased
PLASTICS OR PRODUCTS
BIOBASED AND
BIODEGRADABLE (complete!)PLASTICS OR PRODUCTS
BIOPLASTICS
IMPORTANT:Biodegradability MUST be defined/ constrained by:• the disposal system – composting, anaerobic
digestor• Time – 180 days ; max 1 year• Complete utilization of the substrate carbon by
the microorganisms as measured by the evolved CO2
Ramani Narayan, Michigan State University
DESIGNING FOR BIODEGRADABILITY – WHEN, & WHY?
• Durable Products – BIOBASED [reduced carbon footprint]
• biodegradability is not required element for reasons of performance, safety and long product life
• alternate methods of disposal needs to be identified
• Example -- BIO polyurethanes for automotive and farm vehicles
• Example -- Biofiber composites for industrial and automotive applications
• Example – Biopolyethylene ethanol to ethylene to PE
• BIODEGRADABILITY – For single use, short-life (controlled-life time), disposable products [end-of-life option]
• Like packaging, disposable plastics, agricultural films, marine disposable
• Designed for disposal systems like composting, anaerobic digestion, marine and soil disposal
• BIOBASED is added positive attribute
• IMPORTANT -- Must define environment and time required to ensure complete removal from the environmental compartment otherwise serious environmental and human health consequences
Ramani Narayan, Michigan State University
BIODEGRADABILITY -- END OF LIFE OPTIONS
COMPOSTING FACILITY
COMPOSTING FACILITY RECYCLING
FACILITY
RECYCLING FACILITY
WASTE TO ENERGY FACILITY
WASTE TO ENERGY FACILITY
BiodegradablePlastics
BiodegradablePlastics
RECYCLED PRODUCTS
LAND APPLICATIONrecycling polymeric carbon
back to soil
ENERGY
INCINERABLE
Anaerobic digestion facility
Marine environment
Paper-biopolymer composite
Landfill
X
Unless managed for landfill gas recovery for energy
BIOBASED
PLASTICS
Standards in place for Biodegradability as end-of-life option (Integration of Biodegradable Materials with Disposal Infrasructures)
BiodegradableMaterials
BiodegradableMaterials
COMPOSTING FACILITY
COMPOSTING FACILITY
LAND APPLICATIONrecycling polymeric carbon
back to soil
TEST METHODASTM D5338; ISO14855 1 & 2 ISO16939 (disintegration)ASTM D6340 C-14 SPECIFICATIONSASTM D6400; EN 13432 ISO 17088ASTM D6868 – paper coatings
Waste water treatment
facility
Waste water treatment
facility
ASTM D5271ISO 14851/14852
Anaerobic digestionbiogas energy plant
ASTM D5511ISO 15985
Soil Mulch film
Agriculture appl
Soil Mulch film
Agriculture appl
ASTM D 5988
Marine&fresh water
ASTM D 6691,6692D 7021 specification
Ramani Narayan, Michigan State University, www.msu.edu/~narayan
Ramani Narayan, Michigan State University, www.msu.edu/~narayan
Global Standards for Biodegradability
DIN CERTCOGERMANYBPS
J APAN
USA
Memorandum of UnderstandingCross Certification Program
www.bpiworld.org
EBPATaiwan K BPA
K orea
Composting AssnUK
BPSChina
BPSBrazil
DIN CERTCOGERMANYBPS
J APAN
USA
Memorandum of UnderstandingCross Certification Program
www.bpiworld.org
EBPATaiwan K BPA
K orea
Composting AssnUK
BPSChina
BPSBrazil
DIN CERTCOGERMANYBPS
J APAN
USA
Memorandum of UnderstandingCross Certification Program
www.bpiworld.org
EBPATaiwanEBPA
Taiwan K BPAK oreaK BPAK orea
Composting AssnUK
BPSChinaBPS
China
BPSBrazilBPS
Brazil
ISO 17088Specification for
compostable plastic
Ramani Narayan, Michigan State University
What is this all about?Myths and Green Washing – where is the data?
Industry debates: What’s biodegradable?
Plastics News October 6, 2006
• Oxobiodegradation is a process by which polyolefins can be accelerated to break down into low molecular weight species. Through the action of microbes , the material is transformed into CO2, water and biomass
• Have been used for many years in corn fields – no build of the films in the soil is evident, nor are there any issues with plant growth.
• Company claims that the material meets ASTM D5209, D5338 standards for biodegradability
• Products that conform to D6954 standard which allows for slower breakdown of materials wont get through
“PERF GO GREEN Bags will completely break down in a landfill environment in 12-24 months leaving no residue or harmful toxins and have a shelf life of 2 years.”
Basic Technology
– All of the commodity plastic resins used in the world today will take hundreds of years or more to degrade naturally in the environment
– Plastic products with our additives will biodegrade to become some of the soils’ organic components in a hundredth of that time or less
•Biodegrade
Conclusion
• Make all PE and PP products fully biodegradable• No toxic residue• Manufacture clear or in any color with no appreciable change
in physical properties• FDA compliant for use in applications with food contact• Products can be marketed as “biodegradable” because they
will biodegrade aerobically or anaerobically and without the need for additional reaction to heat, light or physical stress and therefore will biodegrade wherever there is other biodegradation occurring.
Ramani Narayan, Michigan State University, www.msu.edu/~narayan
Quote from Industry website
“The two main types are oxo-biodegradable and hydro-biodegradable. In both cases degradation begins with a chemical process (oxidation or hydrolysis), followed by a biological process. Both types emit CO2 as they degrade, but hydro biodegradable can also emit methane”
The plastic does not just fragment, but is consumed by micro-organisms after the additive has reduced the molecular weight to sub 40,000 Daltons, and it is therefore "biodegradable." This process continues until the material has biodegraded to nothing more than CO2, water, humus, and trace elements.
Oxo-biodegradable plastics Association
www.biodeg.org; Sept 08, 2008
Ramani Narayan, Michigan State University, www.msu.edu/~narayan
The 50% Bio-Batch film did not degrade as completely or as quickly as the cellulose. At the end of the test, 19% of the film had degraded.
The results of the aerobic degradation tests indicate that, in time, plastics produced using Bio-Batch pellets will biodegrade in aerobic conditions.
Ramani Narayan, Michigan State University, www.msu.edu/~narayan
BIODEGRADABILITY CLAIMS Chem. Commun., 2002, (23), 2884 - 2885
– A hypothesis was developed, and successfully tested, to greatly increase the rates of biodegradation of polyolefins, by anchoring minute quantities of glucose, sucrose or lactose, onto functionalized polystyrene (polystyrene-co-maleic anhydride copolymer) and measuring their rates of biodegradation, which were found to be significantly improved
PRESS Sugar turns plastics biodegradable. Bacteria make a meal of sweetened polythene and
polystyrene.
weight loss of only 2-12%,
Only sugar is being assimilated, PE chain intact – Is this a genuine example of biodegradable plastic?
Ramani Narayan, Michigan State University
WHAT IS THE VALUE PROPOSITION FOR BIODEGRADABILITY?
End-of-life option for complete removal of the plastic product from the environmental compartment in a safe and efficacious manner – enter into the microbial food chain!!!
Need to define disposal systems or environment like composting (compostable plastic), anaerobic digestor, soil, marine)
Need to define TIME to complete biodegradation (90%+ of the carbon substrate should be completely assimilated by the microorganisms present in the disposal within a short time period (one year or less)
Degradability, partial biodegradability, or will eventually biodegrade is not an option! – serious health and environmental consequences
ASTM D6400, D6868, D7021 (U.S. Govt procurement law, State of CA, San Francisco India , China, Korea)
EN 13432 European Packaging Directives
ISO 17088 (China, Korea, India)
Ramani Narayan, Michigan State University, www.msu.edu/~narayan
Why Biodegradable Plastics? How does it work?
Low-temperature electron micrograph of a cluster of E. coli bacteria, magnified 10,000 times. Each individual bacterium is oblong shape http://emu.arsusda.gov/default.html
Harness the power of microbes in soil to completely remove the carbon based plastics from the environment.
How?
By ensuing that it is completely consumed by the microorganisms (as its carbon food) for driving its life processes in a short and defined time frame and in the specified environment
the carbon product is taken inside the microbial cell and biologically oxidized to CO2 which releases energy that is utilized by the microorganism for its life processes – to multiply and grow and populate the soil for biological activity
Ramani Narayan, Michigan State University
Microorganisms extract chemical energy for use in their life
processes by the aerobic oxidation of glucose and other
utilizable substrates – BIODEGRADBLE PLASTICS, food waste, paper,
forest residues biological matter
Glucose/C-bioplastic + 6 O2 6 CO2 + 6 H2O; G0’ = -686 kcal/mol
AEROBIC
CO2 is the quantitative measure of the ability of the microrganisms present in the disposal environment to utilize/assimilate the test C-bioplastic, which is the sole C-source available for the microorganisms -- biodegradation/bioassimilation
METRIC FOR BIODEGRADABILITY
ANAEROBIC
Glucose/C-bioplastic 2 lactate; G0’ = -47 kcal/mol
CO2 + CH4
Ramani Narayan, Michigan State University
0
20
40
60
80
100
0 4 8 12 16 20 24 28 32 36 40 44
% C conversion to CO2
time (d)
lag-phase plateau phase
biodegradation degree 65%
biodegradation curve
degradation phase
O2
Compost & Test
Materials
CO2
Radiolabelling methodology – longer duration, can use active compost environment (90+% of carbon converted to CO2 absolute or relative to cellulose/positive control
Cellulose curve must plateau and the time period for control and test material must be the same
Ramani Narayan, Michigan State University, www.msu.edu/~narayan
FUNDAMENTALS -- BASICS
BIODEGRADATION -- BIODEGRADABILITY
Composting
Compostable plastic
Soil Anaerobic digestor
landfills marine
ENVIRONMENT
IN
IN WHAT TIME?
Ramani Narayan, Michigan State University
BIODEGRADABILITY/BIODEGRADATION
In simple terms, biodegradability measures the capacity of microorganisms present in the disposal environment to completely consume the bio carbon product within reasonable and defined time frame in the specified environment.
Composting is one such environment under which biodegradability occurs (compostable plastic) – In the composting environment:
the description of the environment the degree of microbial utilization (percent biodegradation) the time frame within which it occurs
are specified through ASTM D6400 (for plastic products), and ASTM D6868 (for coatings on plastic substrates) standards.
– In the marine environment the requirements are specified in ASTM D7081
Ramani Narayan, Michigan State University
HYDRO, OXO, PHOTO PREFIX DOES NOT MATTER!! Test method is material independent
HYDROLYTIC OXIDATIVE
COMPLETE BIOASSIMILATION/BIODEGRADTION IN
DISPOSAL ENVIRONMENT IN SPECIFIED TIME
Carbon chain polymers
QUESTION IS -- Can the microbial population in the disposal environment completely assimilate/utilize the C-material in one year time frame???
Time & Disposal Environment is the KEY
PVOH – YES
PE/PS + ADDITIVES – NO, NOT IN THE DISPOSAL ENVIRONMENT AND NOT IN ONE-TWO YEAR TIME FRAME
PET –NOPBAT, PBS -- YESCELLULOSE TRIACETATE –NOCA ( around 2.0 ds – yes)PLA (YES, crystallinity is key)
Specification StandardsD6400, D6868, D7021EN 13432ISO 17088
Ramani Narayan, Michigan State University
END OF LIFE OPTIONS
COMPOSTING FACILITY
COMPOSTING FACILITY RECYCLING
FACILITY
RECYCLING FACILITY
WASTE TO ENERGY FACILITY
WASTE TO ENERGY FACILITY
BiodegradablePlastics
BiodegradablePlastics
RECYCLED PRODUCTS
LAND APPLICATIONrecycling polymeric carbon
back to soil
ENERGY
INCINERABLE
Anaerobic digestion facility
Marine environment
Paper-biopolymer composite
Landfill
X
Unless managed for landfill gas recovery for energy
BIOBASED
PLASTICS
Ramani Narayan, Michigan State University
Cradle to Cradle Concept for Material Design(Integration of Biodegradable Materials with Disposal Infrasructures)
BiodegradableMaterials
BiodegradableMaterials
COMPOSTING FACILITY
COMPOSTING FACILITY
LAND APPLICATIONrecycling polymeric carbon
back to soil
TEST METHODASTM D5338; ISO14855 1 & 2 ISO16939 (disintegration)ASTM D6340 C-14 SPECIFICATIONSASTM D6400; EN 13432 ISO 17088ASTM D6868 – paper coatings
Waste water treatment
facility
Waste water treatment
facility
ASTM D5271ISO 14851/14852
Anaerobic digestionbiogas energy plant
ASTM D5511ISO 15985
Soil Mulch film
Agriculture appl
Soil Mulch film
Agriculture appl
ASTM D 5988
Marine&fresh water
ASTM D 6691,6692D 7021 specification
Ramani Narayan, Michigan State University, www.msu.edu/~narayan
Ramani Narayan, Michigan State University
DEGRADABLEVS
BIODEGRADABLE
Biodegradability claim must be qualified by identifying the disposal environment, ensuing complete utilization of the carbon substrate by the microorganisms present in the disposal environment in a short time period – one year or less, and substantiated by the appropriate ASTM, or ISO standards
Degradability, partial biodegradability, or will eventually biodegrade is not an option! – serious health and environmental consequences
Ramani Narayan, Michigan State University
BIODEGRADABILITY
Define Time – complete and short (one growing season)
Define Disposal Environment like composting
Degradability, partial biodegradability, or will eventually biodegrade is not an option! – serious environmental consequences
Ramani Narayan, Michigan State University
Problems with Degradables – Toxic Chemicals Transport
plastic pieces can attract and hold hydrophobic elements like PCB and DDT up to one million times background levels. As a result, floating plastic is like a poison pill -- toxins are carried up the food chain – birds, fishes, and eventually human
– From Algalita Marine Research Foundation – www.algalita.org/pelagic_plastic.html
Plastic residues function as a transport medium for toxic chemicals in the marine environment.
PCBs, DDE, and nonylphenols (NP) were detected in high concentrations in degraded polypropylene (PP) resin pellets collected from four Japanese coasts.
– Mato et al Environ. Sci. Technol. 2001, 35, 318-324
Ramani Narayan, Michigan State University
Captain Charles Moore
Algalita Marine Research Foundation
Plastic fragments with toxins colonized and consumed by birds fishesTransport of toxins up the food chain
Ramani Narayan, Michigan State University
Major Problems/Issues with Degradable Materials/Products
Thompson, R.C. et al. 2004. Lost at sea: Where is all the plastic? Science 304, 838, 2004
Plastic debris around the globe can erode (degrade) away and end up as microscopic granular or fiber-like fragments, and that these fragments have been steadily accumulating in the oceans
fragments come from several sources, the researchers suggest. These include mechanical erosion of nondegradable plastic bottles and packaging, nondegradable parts of biodegradable plastics, and plastic pieces used as abrasives in cleaning agents.
FLOTSAM Lab experiments show that marine animals consume microscopic bits of plastic, as seen here in the digestive tract of an amphipod. © Science 2004
Ramani Narayan, Michigan State University, www.msu.edu/~narayan
Biodegradable Plastic Products Space Confusion Misunderstanding Misinformation Claims without scientific substantiation GETTING BETTER/MUCH BETTER
– ASTM Standards in place D6400 for composting, D6868 for paper coatings modifiers and
additives, D 7021 for marine – specification standards– Certification by BPI based on strict compliance with Standards– Regulations like in CA– Pioneering programs like the one at the city of San Francisco
enforcing compliance of Standards– California Waste Management Board study at Chico State showing
the applicability of Standards and demonstrating “true completely biodegradable plastics in composting conditions”
– Other Community, State, mandates – U.S. Composting Council
Ramani Narayan, Michigan State University
ASTM D6954
7.1 The reporting section must clearly and objectively include the proposed real world applications and disposal environments for which the plastic is being developed with indicated exposure and lifetime expectancies.
7.2 Tier 1—The report must identify the following: 7.2.1 Resin grade plus the commercial name of the formulation additive or
percent of catalyst concentrations. NOTE 8—Identification of test samples needs to be sufficient to inform readers of
the commercial identification of the formulation and of the additives and their availability in the marketplace.
7.2.2 The proposed disposal medium or media for the plastic must be indicated with anticipated life expectancy noted.
7.2.3 The exposure conditions such as temperature, time, moisture, and oxygen concentrations need to be reported.
7.2.4 The exposure conditions and time of exposure (kJ/m 2·nm at 340 nm) to radiation, if used, must be recorded.
7.2.5 Molecular weight and polydispersity index, tensile elongation, and percentage of gels of the samples before and after the indicated time for abiotic test exposure should be reported.
7.2.6 Complete mass balances are to be reported.
Ramani Narayan, Michigan State University
ASTM D6954 (Contd) 7.3 Tier 2—The report must state the following: 7.3.1 Extent of biodegradation (carbon dioxide evolution profile to plateau as
per standards) and expressed as a percentage of total theoretical carbon balance.
7.3.2 Percentage of gel or other nondegradable fractions. 7.3.3 Volatiles produced by the oxidation process. 7.3.4 Temperature and moisture conditions. 7.3.5 Additions of inoculants and moisture and their timing and any additional
mixing procedures. 7.4 Resulting data from Tier 1 combined with data from Tier 2 for comparison
and ranking of polymers under test.
7.5 Tier 3—The report shall include the following: 7.5.1 Detailed description of preparation of material for testing. 7.5.2 Specific testing performed as described in 6.9 with particular emphasis on
any deleterious effects of the soil or aquatic additive. 7.5.3 Regulated metal concentrations, pH, and ability to hold and percolate
water before and following oxobiodegradation testing.
NOTE 5—For determining biodegradation rates under composting conditions, Specification D 6400 is to be used, including test methods and conditions as specified.
Ramani Narayan, Michigan State University
ASTM D 6954 contd -- NOTE
NOTE 5—For determining biodegradation rates under composting conditions, Specification D 6400 is to be used, including test methods and conditions as specified.
At least one temperature must be reasonably close to the end use or disposal temperature, but under no circumstances should this be more than 20°C away from the removed that temperature. It must also be established that the polymer does not undergo a phase change, such as glass transition temperature (Tg) within the temperature range of testing
Standard Guide for Exposing and Testing Plastics that Degrade in the Environment by a Combination of Oxidation and Biodegradation
Ramani Narayan, Michigan State University
ASTM D6400 identified 3 criteriaMineralization (D5338):
Conversion to carbon dioxide, water & biomass via microbial assimilation
60% of carbon conversion to CO2 for homopolymer & 90% carbon conversion to CO2 for block, segmented copolymers, and blends, including addition of low MW additives
Same rate as natural materials Leaves, paper, grass & food scraps
Time -- 180 days or less; if radiolabeled polymer is used 365 days or less
Disintegration <10% of test material on 2mm sieve
– Safety No impacts on plants, using OECD Guide 208 Regulated (heavy) metals less than 50% of EPA
(USA, Canada) prescribed threshold
Specification Standard for Biodegradable/Compostable Plastics
Basis for standards inEurope, Japan, China,
Korea, Taiwan
O2
Compost & Test
Materials
CO2
Ramani Narayan, Michigan State University
TERMINOLOGYBIOBASED (RENEWABLE)Organic material containing in whole or part biogenic (biological sources) carbonRefers to using biomass or crop feedstock (New carbon) vs petroleum or fossil feedstock (OLD carbon)Reducing carbon footprint
BIODEGRADABILITYEND-OF-LIFE option – integrated with disposal systems like composting, and anaerobic digestion or marine or soilfunctional property attribute to be designed and engineered into a biobased product when needed or necessary!!
BIOMATERIALS Refers to:Any material (metal, plastic, ceramic) implanted in the body -- design and engineering considerations different; biodegradability considerations differentBiomedical applications