a statue covered with yellow plastic bag

Have you ever been confused about all the different words used to describe if a product will decompose once being thrown out?

What really is the difference between compostable, biodegradable and degradable?

And what are these new Bio plastic or Plant based plastics?

Today we are trying to make some clarity around all these terms to help you making an informed choices next time you shop.

difference between compostable, biodegradable and degradable

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According To the ABA (Australasian Bioplastic Association) compostable refers to products or materials that will convert into water, carbon dioxide and a small amount of carbon humus.

Compostable products don’t include toxic additives and won’t pollute the soil they end up being.

Within compostable products, a distinction has to be made between commercially compostable and home compostable.

A verified commercially compostable product, when sent to composting with food and other organic waste, will biodegrade in commercial composting conditions within six months.

This means that, if you throw it in your home compost bin, it won’t be likely to decompose because it will need a higher level of sophistication to balance the necessary high heat and microorganism activity for these products to decompose.

On the contrary, a verified home compostable product will biodegrade in six months, when placed into well set up and maintained home composting conditions.

Home compost will work well for your green waste, vegetable scraps, coffee grounds, and leftover grains, it will not do that well with meat, dairy, and fats.

But it will work also with napkins, paper plates, compostable bags, corn plastic cups, etc. IF they have been certified for home composting.

The Australian Standards certifications you are looking for are AS 4736-2006 (biodegradable materials suitable for commercial composting) and Australian Standard AS 5810-2010 (biodegradable plastics suitable for home composting).

If we look more specifically at compostable bags, these are made of natural plant starch, and do not produce any toxic material when decomposing.

If certified for home composting, they can be thrown in your home compost bin; if not, and your council doesn’t have the facility to commercially recycle compostable materials, they will end up in your general rubbish.

Unfortunately, nowadays there are only 150 plants in Australia able to process commercially compostable material and there is no guarantee that a compostable plastic will go to a composting site.

And what will happen to your 100% compostable coffee cup or bag if it’s thrown out together with normal rubbish?

The composting process requires oxygen and, for the most part, landfills are containers within the ground, which are sealed and airtight, therefore oxygen-free.

So, these coffee cups and bags might eventually biodegrade in the landfill, but it will be at a much slower rate and inducing anaerobic composting. Anaerobic composting of plastic-like compostable material made from corn (such as PLA) will produce methane emissions, a greenhouse gas that is about 30 times more potent than carbon dioxide which we are trying to avoid with the whole compostable concept (from the study “Assessment of anaerobic degradation of Ingeo polylactides under accelerated landfill conditions”)

In summary, if your product is not home compostable, there is a high chance that it won’t help much our purpose of reducing the amount of rubbish that ends up in the landfill.


Home compost garden 



All compostable products are also biodegradable but the opposite is not necessarily true.

Still according to the ABA (Australasian Bioplastic Association), biodegradable refers to a natural process during which micro-organisms convert materials into natural substances such as water, carbon dioxide and biomass. The process of biodegradation depends on very specific surrounding environmental conditions (e.g. location or temperature) and on the material itself.

These products should not be disposed of in a composting facility or in your home compost bin as they need specific conditions to be able to break down. Look for what is written on the package for directions on the best way to dispose of them, most of the times they will end up in your general waste bin.

The good part about biodegradable materials is that artificial additives are not needed to facilitate the breaking down process.

However, if we look for example at biodegradable bags, these often still have a component of plastic in them. This means that, when they will eventually start to decompose, they will break down into smaller pieces of plastic that are even more hazardous for the wildlife, who is more likely to eat them.

Also, it will be almost impossible to remove these tiny pieces of plastic from the now polluted landfill, creating almost more damages than throwing out a single plastic bag.

This is the case of many new products launched in the market right now, such as cling wrap or garbage bags, which claim to be 65% plant based, giving you a false reassurance of doing the best thing in buying them.

There is no Australian standardised labelling for biodegradable products which means that there is no time limit on how long it will take them to break down. A product can be called biodegradable and still take 10 years to break down – as long as it eventually happens.

If you don’t have any other option, choose at least products that are 100% biodegradable and takes the least time to break down.



Degradable is different than biodegradable.

Degradable products will similarly break down and disintegrate over time when exposed to very specific conditions of heat and sunlight.

They don’t require bio microorganisms to help the process such as biodegradable products, but chemicals are added instead (including heavy metals) to speed up the decomposition process, increasing even more the pollution of the soil the end up being.

Similarly to biodegradable bags, degradable bags will break down into smaller pieces of plastic, they'll function similarly to petroleum-based plastic and will become quite problematic for animals and the environment.

They will reduce the amount of plastic waste that we see, but the plastic will still be there, just invisible to our eyes.

Degradable bags are neither compostable or biodegradable and will need to be thrown out in your normal waste bin.

You might ask now: can degradable and biodegradable plastic be recycled?

Technically is possible, however it requires very advanced recycling facilities able to recognise and process differently PLA based products and conventional plastic products.

No recycling facilities in Australia have the technology to do so and they won’t accept bioplastic products fearing it will contaminate their recycling stream.

There are only nine composting facilities in Australia able to process bioplastic products (five in NSW, three in QLD, one in Sa and one in WA. Zero in VIC).


 Rubbish plant with escavator



Be careful of these terms:

Bio or plant based: it means the material is made from plant materials rather than fossil fuels, but this doesn't necessarily mean it is biodegradable or compostable.

Bioplastic has two meanings – it could mean the plastic is biodegradable/compostable or that it is made from plant materials.

It can either be made by extracting sugar from plants like corn and sugarcane to convert into polylactic acids (PLAs), or it can be made from polyhydroxyalkanoates (PHAs) engineered from microorganisms. PLA plastic is the cheapest source of bioplastic and the most common type used in plastic bottles, utensils, and textiles. (read more about bio plastic on National Geographic)

It’s not a very reliable term and, as explained above, there is a very little chance these bioplastic products will be correctly processed after being disposed of.

Bioplastic products are in certain ways better than petroleum-based plastic but, in many others, can end up being an example of greenwashing, with consumers misled about how sustainable a product truly is with a Bio prefix that hints at an Earth-friendly product.



We obviously need to improve the recycling and composting infrastructure in Australia so that any product you dispose of can be processed correctly and waste be minimized.

You can also sign for this Change.Org petition asking the Australian government to fund more  onshore recycling facilities

Then, we obviously need to look into reducing, or better avoid, single-use items to reduce the impact we have on the planet and not simply compost more (this petition is asking for a ban on single use plastic in Australia).

Read our blogs on 10 easy ways to start your zero waste journey and 15 tips to reduce your waste for some ideas on which everyday items you can swap!


Turtle eating plastic

Picture credit : Fauna & Flora international
Cover Photo by Anna Shvets from Pexels

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