Both the term biodegradable and compostable are often used to give the impression that a product is more sustainable than other alternatives. But what do those terms mean? Do they present us with better alternatives or are they just misleading us into thinking they are?
What is biodegradable?
Biodegradable refers to a natural process where micro-organisms transform materials into substances such as water, carbon dioxide and biomass over a period of time – this could be from 1 day to 1000 years. So essentially anything that eventually breaks down can be considered biodegradable.
Many businesses label products as biodegradable when they're made from plant material, as there is the assumption that it will break down in landfill over time.
This often misleads us to think that biodegradable products are a sustainable choice, however we don't know how long this product will take to break down and can still produce harmful greenhouse gases and contribute to climate change during this time.
Biodegradable products are not always the most 'environmentally friendly' alternative.
What is compostable?
Composting refers to the breakdown of food and other organic waste into compost which can be used to improve soil. Since composting prevents waste from sitting in landfill and generating harmful gases, it can be seen as the more sustainable option. However, what does it mean when a product packaging or man-made item is compostable?
When a product is labelled compostable it typically implies that the product will break down, similar to food and other organic waste, into compost.
Many products that are labelled compostable have not been tested to prove their compostability. Products that have been certified by the Australasian Bioplastic Association (in Australia and New Zealand or other official bodies in your region) have been tested to safely degrade in specified time frames.
Compostable: check for certification
In Australia and New Zealand, we have the Australasian Bioplastic Association (ABA) which helps identify certified compostable products and inform on how to dispose of them after usage. There are two main certifications, home compostable and commercial compostable. The key difference between the two are the methods of disposal.
Certified home compostable:
Products can be certified for home compostability. AS5810 certified products should be able to disintegrate after 180 days and completely biodegrade after 12 months in a home composting system.
A home composting system can include a worm farm or home composting system such as hot or cold composting.
Certified commercial compostable:
Products can also be certified for commercial compostability. AS4736 certified products should be able to disintegrate after 12 weeks and completely biodegrade after six months in a commercial composting or a commercial organics recycling facility.
A commercial organics recycling facility includes large industrial facilities with large-scale composting abilities. There are very few commercial organics recycling facilities accessible to individuals.
Is compostable or biodegradable better?
Understanding the difference between biodegradable and compostable is challenging due to the lack of regulation and mis-use.
Certified compostable products have proven to break down in certain time frames compared to biodegradable products which have no testing or proof.
We encourage you to choose certified home compostable (AS 5810) as these products can be composted in your own worm farm or home composting system. If you don't have a home compost, you may be able to find a neighbour or community group with one close to you via ShareWaste.
Most individuals do not have access to a commercial composter, but if you do, you may be able to compost certified commercial compostable products.
To complicate things further, there are also instances where certifications are not required, such as paper towels or corrugated cardboard. These products are made with paper fibre and are home compostable by nature.
While it's not always possible to make the most sustainable choice, understanding different materials and their lifecycles empowers us to make better decisions.
Ultimately, reducing and reusing whenever possible are the most effective ways to minimise environmental impact