Bioplastics compostability – What you need to know

A lot has been written about bioplastics’ biodegradability properties and their ability to be composted, or “organically recycled” as some legislations in Europe would call it. When bioplastics originally hit the market some 18 years ago, there was some misconception that all were compostable and that therefore, much of the global petrochemical plastics industry would convert, especially short cycle packaging applications.

This perception has not come to fruition, and in fact, was based on unrealistic assumptions about the role of biodegradable properties in plastic applications.

In order to understand the current state of affairs with biodegradable bioplastics, let’s start with a few definitions in different parts of the world. In the US the Society of the Plastic Industry’s (SPI) definition of bioplastics is: ”plastic that is biodegradable, has biobased content or both. In Europe, according to http://en.european-bioplastics.org’ s definition, “bioplastics are biobased, biodegradable or both”. Close enough.

Those definitions have two words ‘biodegradable’ and ‘biobased’ that are further defined as follows:

  • Biodegradable means a plastic that undergoes biodegradation as per accepted industry standards. As of 2013, accepted industry standard specifications include: ASTM D6400, ASTM D6868, ASTM D7081, ISO 17088 and EN 13432. Degradation results from the action of naturally occurring microorganisms – bacteria, fungi and algae. The referenced standards dictate specific levels of temperature, moisture, micro-organisms, and most importantly time, in order for biodegradation to be achieved. The micro-organism uses the plastic as a food and energy source. Biodegradation also assumes that there is complete assimilation of degraded products to ensure return of carbon to the ecosystem. Biodegradable bioplastics are most applicable in single-use, short life disposable packaging and consumer goods. There are other applications such as agricultural mulch film and food waste bags.
  • Biobased means, for the SPI, an organic material where carbon is derived from a renewable resource via biological processes. A well known n example is corn, more precisely starch from corn used for first generation bio-fuels or bio-plastics such as Polylactic acid (PLA) via a fermentation process. The second generation bio-plastics will come from non-feed renewable agricultural by-products like straw that will deliver cellulosic sugars and lignin via a fractionation process. The biobased content is the fraction of the carbon content which is new carbon made up of biological materials or agricultural resources versus fossil carbon or old carbon content. Biobased content is measured in the US following the procedures set by ASTM D6866. In Europe, the definition of European Bioplastics is slightly different: the term biobased describes the part of a material or product that stems from biomass. When making a biobased claim, the unit (biobased carbon content or biobased mass content), a percentage, and the method of measurement should be clearly stated.
  • Compostability – In most applications where biodegradation is the desired end-of-life (EOL) scenario, composting is the usual mechanism to achieve that result. Composting is an environmentally sound approach to transferring biodegradable waste into useful product. To be compostable a material must:
      • Disintegrate quickly, leaving no visible residue that has to be screened out
      • Biodegrade fully or convert rapidly to CO2, water and biomass
      • Not introduce high levels of regulated (heavy) metals into the soil.
      • Not disrupt, in any way, the ability of the compost to be used in a manner that supports plant growth

ASTM, ISO and CEN (EN) standards incorporate the technical procedures and testing necessary to ensure compliance with the standards. However, they do not cover the marketing aspects of presenting a product or package to the consumer with sensible information on the variety of end-of-life options including composting.

It should be noted a test method standard is not a product specification. Some of these standards limit themselves to state that the rules for performing a laboratory test are defined.

The reference manuals for the understanding of compostable bioplastics are the FTC Green Guides and the European Bioplastics’ Environmental Communications Guide for Bioplastics. Both of these are reader-friendly guidelines aimed at helping marketers ensure that the claims they make about the environmental attributes of their products are truthful and non-deceptive.

Regarding compostability, section IV of Green Guides clarifies that phrases like ‘‘timely manner’’ means ‘‘in approximately the same time as the materials with which it is composted.’’ The Guides also state that marketers clearly qualify compostable claims if, for example, their product cannot be composted safely or in a timely manner at home, or if necessary large-scale facilities are not available to a substantial majority of the marketer’s consumers.
Images intégrées 4

Source: Zoysia Farms Nursery

There is another compostability nuance to the Guides that is often overlooked by brand owners and retailers. This nuance is—even if the package or product meets all the technical aspects of composting, like complete breakdown, time, etc., there must be compost facilities available in the geographical area where the package or product is discarded. “To avoid deception about the limited availability of municipal or institutional composting facilities, a marketer should clearly and prominently qualify compostable claims if such facilities are not available to a substantial majority of consumers or communities where the item is sold.”

In conclusion, if you are selling a product or package and making an environmental claim, it must have competent and reliable scientific evidence that all the materials in the item will break down into, or otherwise become part of, usable compost in a safe and timely manner in an appropriate composting facility, or home compost pile or device available in the area where the product is sold. !
Another aspect of compostability is product certification. This can be handy for the many items within the food service industry. This industry has a way to identify material that is certifiable in compost facilities that recognize the certification compliance. The most widely know certification program in the U.S. is the Biodegradable Product Institute (BPI).

Europe, Japan and China have certification standards for biodegradation by composting. DIN CERTCO is the registration agency in Europe certifying passage of all required testing according to EN-13432.

The main stumbling blocks to a rapid development of biodegradable bioplastics – Clearly, in applications that lend themselves to a biodegradable solution, like food service packaging, biodegradable bioplastics serve a viable purpose. There are still, however, two key issues: the full geographical availability and the full suitability of compost facilities. Even if locally available, many private and municipal compost facilities in the US or Europe will not take biodegradable food service articles because in many cases, they do not fully compost in their specific operation. Additionally, the introduction of food service articles, even if fully biodegradable, potentially will prevent compost from being certified organic.

The lack of composting infrastructure and a thorough understanding of the composting process at the consumer level have contributed to the slow market development of compost-friendly bioplastics. The polymer technology was way ahead of the market’s ability to utilize the technology. Many of the leading compostable biopolymer companies like Metabolix/Archer Daniel Midland , Natureworks/ Cargill or Cereplast have or are dissolving operations or focusing new developments where biodegradation is not driving the biopolymer adoption. This shift in focus may be a sign that biodegradability may not be the ‘silver bullet’ everyone was led to believe it could be. At least in the short term, until private and public waste collection and treatment institutions roll-out a dense enough network of adequate composting facility replacing incinerators and landfills.

Conclusion There is still a viable market segment for biodegradable bioplastics. These bioplastics will eventually find their application and market driven level of acceptance, but it will take the continued efforts of progressive composters, informed consumers and agreement from all stakeholders on upgraded meaningful standards that match real world composting conditions.

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