Biodegradable plastics are plastics degraded by microorganisms into water, carbon dioxide (or methane) and biomass under specified conditions
Biodegradable plastics are plastics degraded by microorganisms into water, carbon dioxide (or methane) and biomass under specified conditions
The first generation of degradable plastics (early 1990s), polyolefin-starch materials, did not degrade as claimed.
Since that time, universal standards have been developed , new materials have been introduced, and a compostable logo has been developed to guide consumers in their decision-making.
Biodegradable plastics are plastics that are capable of being decomposed by bacteria or other living organisms.
Two basic classes of biodegradable plastics exist:
Biodegradable plastics offer a value proposition for a series of single and/or short-term use applications:
Organic waste collection and diversion Agricultural and horticultural sectors (e.g. as mulch-films or plant pots) Food packaging Disposable tableware (closed systems)
The material can be foamed into packing materials, it can be extruded, and it can be injection-molded in modified conventional machines. Different types of fillers can be used with the system, such as wood flour, lime, clay, or waste paper (and other organic and inorganic fillers). The fillers may be colored or used in various granulation sizes to change the material´s external appearance.
The material can be co-injected with other plastic materials such as LDPE, PP, and HDPE. The co-injection process deposits a thin film of plastic material over the top of this material. Co-injection of biodegradable plastics would yield a completely biodegradable item that is cheaper than conventional plastic materials, completely water proof, and colored to match conventional plastic materials.
Certified biodegradable products that are intentionally designed to be recovered by means of organic recycling are expected to be treated in composting plants or anaerobic digestors. Mechanical recycling is usually not the proper recovery option for these materials.
Biodegradable plastics are not designed to be thrown away in the environment and should not encourage a throw-away mentality.
Biodegradable plastics biodegrade in controlled environments under defined conditions.
Like traditional plastics, biodegradable plastics do not degrade efficiently in landfills due to the lack of oxygen and humidity, and the low temperatures.
Establishment of sound waste management combined with education and raising environmental awareness is the only sustainable solution.
DEFINITON
What are biodegradable/compostable plastics and what standards apply to them?
Biodegradable plastics are plastics degraded by the action of microorganisms and enzymes. The mineralization of organic structures by microorganisms converts the material into carbon dioxide, methane (if the process occurs under anaerobic conditions), water and biomass. Compostable plastics are biodegradable plastics that undergo a biodegradation process under controlled conditions (temperature, oxygen and humidity), typical of industrial composting facilities. Under those aerobic composting conditions the formation of methane is avoided and only water and CO2 are produced. In Europe, claims of biodegradability of packaging and plastics waste in composting applications are currently regulated by EN 13432 and EN 14995, respectively. To avoid disruption of waste treatment facilities it is important that only plastic waste that is compliant with the official compostability standards and the requirements of the respective facility enters composting or digestion streams. Examples of other international standards for compostability include GreenPla, AS 4736 and ASTM D6400.
FUNCTIONALITY
What differentiates bio-based and biodegradable plastics from conventional plastics?
The term bioplastics covers plastics made from renewable resources (bio-based plastics), including plastics that biodegrade under controlled conditions at the end of their use phase. Biodegradable plastics may be derived from renewable resources such as starch, but may also be derived from fossil feedstock, e.g.polycaprolactone. On the other hand, some bio-based plastics have the same structure and material properties as conventional plastics, e.g., bio-polyethylene, bio-polyvinylchloride, bio-polyethylene terephthalate. In this case, the only difference compared to the conventional equivalent is the origin of at least part of their feedstock. There are also a number of bio-based plastics that have no conventional plastic equivalents. Examples are polylactic acid, certain polyamides as well as polyhydroxyalkanoates. These materials have innovative properties that bring additional value to the applications in which they are used.
What are typical applications for bio-based and biodegradable plastics?
Bio-based and biodegradable plastics offer a value proposition for a series of applications. Biodegradable plastics are used in single or short-term use applications such as organic waste collection and diversion, in agricultural and horticultural sectors (e.g., as mulch-films or plant pots) and in packaging applications. Bio-based, plastics can be used in long-lasting applications, such as: automotive, E&E, sports and leisure, and furniture. Due to the rapid growth of the sector and continuous innovations, a wider range of applications is expected to emerge in the coming years.
SUSTAINABILITY/RESOURCE EFFICIENCY
How do bio-based and biodegradable plastics contribute to resource efficiency and climate protection?
The use of renewable resources for the production of bio-based products is often seen as a means of reducing the dependency of the plastics industry on fossil resources. Furthermore, in some cases there may also be a contribution to climate protection through the reduction of greenhouse gas emissions, particularly CO2. However, as for any other material or product, environmental benefits need to be proven by a life cycle assessment approach. Like conventional plastics, bio-based plastics can be used to reduce energy consumption. For example, high performance bio-based plastics can replace some metal parts in transport applications hence reducing weight and energy consumption. The exploitation of biomass waste derived from agricultural productions and forestry, for the production of bio-based plastics could represent a significant contribution to resource efficiency (waste as feedstock for industrial use) and climate protection. It therefore merits further research efforts and technical development. Compostable plastic waste bags support clean separation and collection of organic waste and divert organic waste from landfill towards high-quality compost production. Composting is of particular importance when soil erosion is a serious problem. In the future, the European Union will require its member states to collect and dispose of organic waste separately. In Europe today, only 30% of compostable waste is separated from the rest[3] – many countries still deposit it in the same landfill with non-compostable waste. If all of Europe collected and composted its organic waste separately, greenhouse gas emissions from waste disposal could be reduced by 30%.[4]
Is it feasible and would it make sense to replace all conventional plastics with bio-based and biodegradable plastics?
No, this is neither feasible nor would it make sense. Nowadays the bio-based and biodegradable plastics market represents less than 1% of all plastics produced. Although production capacity is expected to grow at about 20% per year, bio-based and biodegradable plastics will continue to be a niche segment in the next few decades. Furthermore, plastics are resource efficient materials in many applications and help to save resources and improve quality of life in many ways during their use phase. Overall, the plastics industry should continue to strive towards a more efficient use of all kinds of resources, irrespective of their origin.
Are bio-based and biodegradable plastics more sustainable than conventional plastics?
PAGEV recommends that any product environmental impact should be measured using comprehensive Life Cycle Assessments together with cost evaluations. It is not correct to assume that bio-based and biodegradable plastics have by definition a lower environmental impact than conventional plastics.
TECHNOLOGY & MARKET
What is the production capacity for bio-based and biodegradable plastics (globally and by regions)?
A recent market study published by EuropeanBioplastics(2) estimated that in 2011 the global bio-based and biodegradable plastics production capacity amounted to 1,161,000 tons. Of this amount, biodegradable plastics (including non-bio-based) accounted for 486,000 tons of and bio-based (non-biodegradable) plastics for 675,000 tons. In 2011, the production capacity was distributed evenly between South America and Asia and on a minor extent between Europe and North America. However, the forecast for the year 2016 predicts significant growth of the Asian production capacity (the proportion of production capacity share is expected to increase from 34.6% in 2011 to 46.3% in 2016) and a progressive decline in the share of production capacity in Europe (from 18.5% to 4.9%).
How fast is the market for bio-based and biodegradable plastics expected to grow in the coming years?
Production capacity is forecasted to grow at about 20% per year until 2016, whereby the highest contribution to growth will come from bio-based (non-biodegradable) plastics.
Can bio-based and biodegradable plastics be processed with conventional plastics processing technologies?
Many bio-based plastics like bio-PE, bio-PET, bio-PA and bio-PVC have the same chemical and mechanical properties of the corresponding fossil-based materials. As a result, they can be processed in the same way as their conventional equivalents. Other bio-based and biodegradable plastics also offer drop-in solutions, and can be processed with existing equipment even though they do not have any fossil-based equivalents. As with any new material, it is not possible to give a generalized answer. The situation must be considered on a case-by-case basis.
END OF LIFE
How can compostable plastics be disposed of? How does composting work?
Compostable plastics used in food packaging applications, catering or for the collection of organic waste can be disposed via industrial/municipal composting facilities. Microorganisms such as fungi and bacteria produce enzymes that can metabolize biodegradable plastics: • The polymer becomes their source of food and energy; • The microorganisms transform the biodegradable plastic product into carbon dioxide, water and biomass. Microorganisms require certain levels of temperature, heat, water and oxygen for efficient and effective biodegradation. Conditions for home composting are significantly different from those in industrial/municipal facilities. As a result, many products that meet the requirements of EN13432 in industrial/commercial composting facilities will not do so in a home composting situation.
Do compostable plastics biodegrade in landfill and contribute to GHG emissions?
In contrast to conventional plastics, compostable plastics are prone to aerobic or anaerobic biodegradation and are designed to be recovered, together with organic waste, in industrial composting facilities or organic digesters. Compostable plastics as well as conventional plastics are too valuable materials and should not be disposed of in landfills. PAGEV supports the policy of "zero plastic waste going to landfill”. In properly managed landfills, humidity and temperature are too low to trigger a consistent material degradation; therefore, the majority of compostable plastics, like conventional plastics, do not biodegrade. Nevertheless, it should be noted that the family of biodegradable plastics comprises a big ranges of materials and test results on the biodegradability of plastics materials under landfill conditions exists only for a limited number of products.
Is biodegradability a solution to the problem of litter and marine litter?
Biodegradable plastics are frequently quoted as a remedy to solve the issue of littering. However, biodegradability or any other form of enhanced degradation of plastics does not resolve the litter issue. The causes of littering are lack of a suitable waste management system and infrastructure as well as bad human behavior. Establishment of a sound waste management system combined with education and raising environmental awareness is the only sustainable solution for litter. Plastic products are also valuable at the end of their use phase - as material or as energy resource - and should not be littered. [1] If a yield of 2 metric tons biopolymer per hectar of land is considered.
FOOTNOTES:
[2] Source:
a) European Bioplastics, 2012.
b) „Globale landflächen und biomasse nachhaltig und ressourcenschonend nutzten",
umweltbundesamt, 2012, page 8.
[3] ORBIT e.V. / European Compost Network ECN ""Compost production and use in the EU",
2008.
[4]
a) BASF Ecoefficiency analysis, 2011.
b) "Waste opportunities Past and future climate benefits from better municipal waste
management in Europe” EEA Report /No 3/2011
[5] EuropeanBioplastics, Fact Sheets „Mechanical Recycling", 2010
