What’s the difference between biodegradable, degradable and compostable?

What’s the difference between biodegradable, degradable and compostable?
More than ever, products are being labelled with the way they break down, but what does it all mean? It can be hard to work out what the difference between biodegradable, degradable and compostable is, and how you can properly dispose of them. So, we’ve broken it down to explain the difference (pun intended) and included some shocking truths!

What is biodegradable?

In the right conditions, a biodegradable substance will break down naturally into organic compounds. Eventually these compounds will be absorbed by the earth. In terms of environmental benefits, the best biodegradable materials are the ones that break down the quickest, leaving no harmful substances behind and saving on landfill space. The process of biodegradation relies on bacteria, fungi or microorganisms to break down a substance, however, as not all substances are created equal, neither are their requirements to break down.

Anaerobic vs. aerobic biodegradation

There are 2 ways for biodegradable substances to break down: anaerobically or aerobically.
Both processes require the presence of microorganisms, fungi or bacteria. When something degrades aerobically, it does so in the presence of oxygen, with microorganisms and other bacteria consuming the biodegradable waste, leading to a release of water and some carbon dioxide. With aerobic biodegradation most of the nutrients from broken down materials will return back to the soil.
 Anaerobic biodegradation occurs without the presence of oxygen (the most common process in landfill). This takes significantly longer than what a substance would take to break down if it was in nature or in compost and can also let off gasses like methane and carbon dioxide.

How do you dispose biodegradable items?

Not all items that are biodegradable are compostable, but all items that are compostable are biodegradable. Items like fruit, vegetables, paper and plants can be composted at home otherwise, things like biodegradable cutlery, plastic cups, packaging and plastic bags will need to go into the general waste bin as they cannot go through the regular recycling process. Due to a lack of micro-organisms, oxygen and light, items that would ordinarily break down quickly in nature or through composting, can take just as long as some plastics to break down. (Scary fact: it can take one head of lettuce 25 years to break down in landfill!)

What is degradable? 

Degradable is one of the scariest break-down methods of them all and can result in the release of micro-plastics into the environment. Unlike biodegradable substances, degradable materials do not require bacteria and micro-organisms to break down. Instead they are made from are made from plastic with chemicals and heavy metals added to speed up the break down process when exposed to sunlight and heat (you may have come across degradable plastic bags). If degradable bags are released into the environment, they can break down into tiny microplastics which are a lot harder to remove than a plastic bag, and are more easily consumed by animals.

How do you dispose of degradable items?

Degradable items should only be placed in the general waste bin.

What is compostable?

 Ah, compostable. The favourite child of break down methods. Simply put, composting works when organic material is eaten and broken down by by micro-organisms in the presence of oxygen. This process heats up the compost (to help it further break down) and releases some carbon dioxide, leaving behind a nutrient dense fertiliser soil that can be spread on house plants and the garden. What’s not to love about that?
You may have seen compostable items replacing single use plastics, and that’s great, but you may not be able to compost these items at home.

Home composting vs. commercial composting

The principal of composting remains the same between home and commercial composting with organic material being eaten and broken down by micro-organisms – they even get the same nutrient dense fertiliser soil by-product. Commercial composting is on a much larger scale than home composting and is a highly efficient composting process. Unlike home composting, commercial composting facilities can monitor and control temperature, moisture and airflow as well as using machinery such as grinders and mixers to further break down larger items. These processes, make the organic matter more manageable for microbes to breakdown.
The main difference between home composting and commercial composting, is that commercial composting can break down compostable items a lot quicker than home composting, with some compostable items only compostable through commercial facilities (due to the time it would take them to break down at home). For compostable cutlery and packaging that says it’s only compostable through commercial facilities, we have some bad news: if you don’t have access to a commercial composting facility, you may need to dispose of this in general waste. Technically compostable plastics can be recycled; however, they need to be separated from the other plastics, which our recycling facilities in Australia aren’t yet set up to do. If these commercially compostable items then end up in landfill, they are no longer in the ideal conditions to be composted and can take as long as some plastics to break down.

How to compost at home?

There are many ways you can compost at home whether it is with a compost tumbler (our favourite), an on the ground compost unit, a worm farm or a bokashi bin. The type of organic waste you are able to add to compost varies depending on the type of composting unit you are using. Make sure you do your research into which unit suits your lifestyle (and waste), as adding the wrong organic waste can upset the balance of your composting (e.g. worms do NOT like garlic, chilli or citrus!)

How can you help?

When using cutlery, bags, food storage, packaging, water bottles, hand soap bottles or anything considered to be single use, reusable is best. This way, you’re doing the environment a favour by keeping more stuff out of landfill. If you’re not sure where to start, we’ve put together a how-to guide for living more sustainably. For the rest try and apply your sustainable mind to the things you are using and consuming. You can ask yourself things like: can it be composted at home? If not, do you have access to a commercial composting facility? If you have the option between a biodegradable item or a recyclable item, how do you feel about the biodegradable needing to go into general waste?