Biodegradable, compostable, oxo-degradable… what does it mean?

Some do have very specific meaning while others might refer to a loose concept. Here we explore some of the most common environmental claims.

A brand owner or manufacturer might want to display the properties of specific products to describe how a product can be discarded (e.g. recyclable), how it may interact with the environment (e.g. oxo-degradable), or the type of material it was made of (e.g. bio-based)… Those statements are called “environmental claims”.

1. Recyclable

Waste that could be recovered and processed into material suitable for the manufacture of a useful new product.

As per ISO14021 on environmental self-declaration, a company can claim a product recyclable if it meets the following criteria:

  1. Customers have a reasonable access to a recycling program
  2. Technologies are available locally to sort and then recycle the product
  3. There is a market for the recycled material

In many cases, companies make recyclability claims based on national, overseas, or international guidelines, or internal assessments. This results in discrepancies.

As a result, industry organisations have implemented in different countries a standardised approach to assess the recyclability of packaging in specific countries:

  • OPRL (On-Pack Recycling Label) in the United Kingdom.
  • ARL (Australasian Recycling Label) in Australia and New Zealand.
  • How2Recycle in the United States and Canada.
  • L4R (Label for Recycling) in Singapore.

2. Biodegradable and compostable

Biodegradable: Materials that can be broken down by microorganism into simple, stable compounds such as carbon dioxide and water.

Biodegradation is a chemical process in which materials are metabolised into water, carbon dioxide, and biomass with the help of microorganisms. The process of biodegradation depends on the environmental conditions, which influence it (e.g. temperature, inoculum, humidity, etc.), and on the material or application itself. To claim a product’s biodegradability, the ambient conditions have to be specified and a timeframe for biodegradation must be set in order to make claims measurable and comparable. This is regulated in the applicable standards.

Compost: organic residues, or a mixture of organic residues and soil, that have undergone thermophilic decomposition to achieve pasteurisation and a specified level of maturity.

In order to be recovered by means of organic recycling (composting) a material or product needs to be biodegradable. Compostability is a characteristic of a product, packaging or associated component that allows it to biodegrade under specific conditions (e.g. a certain temperature, timeframe, etc). These specific conditions are described in standards, such as the European standard on industrial composting EN 13432 (for packaging) or EN 14995 (for plastic materials in general). Materials and products complying with this standard can be certified and labelled accordingly.

Please note that in order to make accurate and specific claims about compostability the location (home, industrial) and timeframe need to be specified.

  • Standards for industrial composting and anaerobic digestion

The harmonised European standard EN 13432 “Requirements for packaging recoverable through composting and biodegradation” requires at least 90% disintegration after twelve weeks, 90% biodegradation (CO2 evolvement) in six months, and includes tests on ecotoxicity and heavy metal content. It is the standard for biodegradable packaging designed for treatment in industrial composting facilities and anaerobic digestion.

  • Standards for home composting

While there is currently no international standard specifying the conditions for home composting of biodegradable plastics.

Belgian certifier Vinçotte (now TÜV AUSTRIA Belgium) had developed the OK compost home certification scheme, requiring at least 90% degradation in 12 months at ambient temperature.

  • Biodegradability in soil

The certification scheme “Bio products – degradation in soil” developed by TÜV AUSTRIA Belgium (former Vinçotte) is based on EN13432/EN14995 (Standards for the industrial composting of packaging/plastics) and adapted for the degradation in soil. The test demands at least 90% biodegradation in two years at ambient temperatures.

  • Biodegradability in marine environments

Currently, there is no standard providing clear pass/fail criteria for the degradation of plastics in sea water.

TÜV AUSTRIA Belgium (former Vinçotte) has developed a certification scheme based on ASTM D7081, which demands a biodegradation of at least 90% in 6 months. The corresponding label is OK biodegradable MARINE.

3. Bio based

The term bio-based describes the part of a material or product that stems from biomass (EN 16575).

This term is particularly loose, as illustrated in Figure 1. When making a bio-based claim, the unit (bio-based carbon content/ bio-based mass content), a percentage and the measuring method should be clearly stated.

 

Overview of plastic types compared to its natural or fossil origins and bio or non-biodegradable
Figure 1 - Overview of plastic types compared to its natural or fossil origins and bio or non-biodegradable

4. Oxo-degradable

Oxo-degradation (or oxidative degradation) is defined as degradation identified as resulting from oxidative cleavage of macromolecules.

In other words, oxo-degradable plastics are conventional polymers (such as LDPE) to which chemicals are added to accelerate the oxidation and fragmentation of the material under the action of UV light and/or heat, and oxygen.

This type of plastic is highly criticised for worsening the management of plastic waste both in the recycling process and pollution of natural environments.

Sources:

[1] According to Singapore Standards SS 594:2014
[2] https://www.european-bioplastics.org/faq-items/what-is-the-difference-between-biodegradable-and-compostable/
[3] Complete biodegradation of the plastic material has occurred when 90% or more of the original material has been converted to CO2. The remaining share is converted into water and biomass, which no longer contains any plastic.
[4] https://docs.european-bioplastics.org/2016/publications/EUBP_environmental_communications_guide.pdf
[5] https://www.european-bioplastics.org/bioplastics/materials/
[6] European Standards Organisation (CEN), CEN/TR 15351:2006 Plastics – Guide for vocabulary in the field of degradable and biodegradable polymers and plastic items
[7] Statement letter by the New Plastic Economy https://ecostandard.org/wp-content/uploads/oxo-statement.pdf

 

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About Zero Waste City

Zero Waste City is a consulting business specialised in waste reduction for commercial and industrial facilities. We help companies to save money by reducing waste and to achieve Zero Waste goals. Our services include:

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