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BIODEGRADABLE VS. COMPOSTABLE.

Updated: Mar 4

We often hear the terms biodegradable and compostable on the label of a number of products these days, but what does it all mean and what is the difference?



What do we mean by ‘biodegradable’?

In the plastic packaging industry, ‘biodegradable’ was often used to refer to plastic bags breaking down in landfill or in natural environments. However, the term has little significance without industry standards or benchmarks against which we can determine the ‘biodegradability’ of a piece of plastic. In fact, there is nothing that does not degrade in nature. Even steel oxidizes and corrodes over time but this process can take many years just as it does with plastics. So what do we mean by ‘biodegradable’? In the plastic packaging industry, the term has referred to plastic packaging to which additives were added, for it to more rapidly disintegrate in landfill or nature. Whilst this was a step forward, it is not the silver bullet we need when it comes to reducing waste. This process can still take many years but what is more troubling is that it leaves toxic residue or micro-plastics in the environment. Some might argue, that we are no better off with this solution. So, what then? What is ‘oxo-degradable’? Even more recently, particularly the early 2000s, ‘oxo-degradable’ became quite popular in the plastic packaging industry. Similar to ‘biodegradable’ packaging, oxo-degradable packaging also consisted of additives that allowed it to break down anywhere, as long as oxygen was present. Over time, bags would break into smaller fragments and eventually break down into microplastics (sound familiar?) however, it too was not the solution to our waste problems. Not only did it still take time but the microplastics would be found in more populated areas, posing a danger to humans and animals.


What is compostable packaging?

Enter, ‘compostable’ packaging. Why ‘compostable’ and not ‘biodegradable’? Even though we may use the term interchangeably as most people understand the term ‘biodegradable’ rather than compostable, what we really mean at Adventpac is compostable. When we say our Greenpac™ is 100% compostable, we don’t mean ‘biodegradable’ in the traditional sense. Composting is a form of waste disposal where organic waste such as food decomposes naturally under oxygen and microbe-rich conditions. There are industrial compost facilities and composting systems for the home (e.g. a worm farm, a compost bin, or bokashi system). It is in these facilities or systems that compostable packaging should be disposed of. Why? Well, compostable packaging is made of raw materials (e.g. corn starch) that naturally decompose in microbe and oxygen-rich environments just like organic waste. The benefit of this is that not only does the packaging not end up in landfill but when turned in compost, can help fertilize plants and vegetation. Finally, a genuine step forward for sustainable packaging! BUT WAIT! Now, you’re an expert in the technical terms but there’s more that we need to understand. Just because something is labelled ‘compostable’ does not mean it is ‘compostable’. What do we mean by that? There are different compostability standards for compostable packaging and understanding the differences between them will help you determine the necessary conditions required for them to decompose as well as how long you can expect it to take. In Australia, there are two standards for compostable packaging: AS 4736 and AS 5810 which we will go through down below. AS 4736-2006: Industrial Compostability In Australia, for a plastic material to be certified as compostable, it must comply with the AS 4736-2006 standard. This standard is similar to the European EN 13432 standard but has an additional requirement of a worm test. The AS 4736-2006 standard provides the criteria against which plastics materials that are to be biodegraded in industrial anaerobic composting facilities, are assessed. It is important to note that industrial compost facilities are very different to home composting systems. Industrial composting facilities are able to process organic waste at high temperatures that cannot be replicated in the home (50°C or higher), thus accelerating the rate at which the waste decomposes. Therefore, just because something has been certified for the AS 4736-2006 standard, does not mean it will decompose in the same way in a home compost system!

In order to comply with the AS 4736‐2006, plastic materials need to meet the following requirements:

  • Minimum of 90% biodegradation of plastic materials within 180 days in compost

  • Minimum of 90% of plastic materials should disintegrate into less than 2mm pieces in compost within 12 weeks

  • No toxic effect of the resulting compost on plants and earthworms.

  • Hazardous substances such as heavy metals should not be present above the maximum allowed levels

  • Plastic materials should contain more than 50% organic materials.

Products that meet the requirements above can be endorsed with the ABA Seedling Composting Logo. This logo ensures that these products and materials are easily recognized and food waste or organic waste contained in these certified products can be easily separated out and diverted from landfill. AS 5810-2010: Home Compostable Although a home composting system is very different to that of an industrial facilty, the core requirements for the certification remain the same. For a plastic material to be ceritified to the AS 5810-2010 standard, it must undergo stringent testing conducted by recognised and accredited third-parties. Due to the differences between a home compost system and industrial compost facilty, the testing period for this standard is a maximum of 12 months however, the end results remain the same as the AS 4736-2006 standard. That means a minimum of 90% biodegredation, no toxic effect to compost, plants and earthworms and materials should contain more than 50% organic material. If successful, applicants will be granted the license to use the home compostable logo on their packaging. This logo will help the end consumer, customers and/or municipal authorities to recognise compostable packaging and dispose of it accordingly. More importantly, the Home Compostable Verification logo will communicate the authenticity and independent verification of claims of compliance to AS 5810-2010.

Which Should I Choose?

Due to the extreme and stringent requirements of the AS 5810-2010 standards, it holds true that whichever product meets the home compostable standard, it will meet the industrial standard. The opposite however, does not always hold true. The choice as to which certification you should settle for will depend on who the end user is. At the time of writing, industrial compost systems are not widely available and accessible for the majority of the population in Australia as is the case in many other parts of the world. So, if you know that either you or your customer will not have easy access to an industrial compost facility, it is best to ensure that you choose packaging that has been certified to AS5810-2010 as this will allow anyone with a home compost system to easily dispose of it properly and reduce the amount of waste that ends up in landfill.

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