Biodegradable vs Compostable vs Oxo-degradable: The sustainability of bioplastics explained

For example, the production of bioplastics is expected to increase by as much as 20% by 2022!  The three types of bioplastics available are biodegradable, compostable, and oxo-degradable. However, many businesses mix up the differences between these bioplastics and this could lead to dire consequences if they are disposed of incorrectly. In this article, we will define the differences that you need to know about each of these bioplastics.

What is ‘Biodegradable’?

‘Biodegradable’ is a term that has no official definition or requirements, so it often misleads brands, retailers, and consumers. A substance is biodegradable if it is “capable of being decomposed by bacteria or other living organisms.” Some products, such as food and plants, are naturally biodegradable, whilst others can break down into harmful gasses or substances.

Even though all compostable plastics are biodegradable, not all biodegradable plastics are compostable. This means even though naturally occurring organic compounds can be biodegradable, it could take hundreds or thousands of years to decompose. It is important to recognise the term ‘biodegradable’ does not define the length of time needed for your products to decompose. For example, plastic bags may be labelled as ‘biodegradable’, but it does not mean they are a good option for protecting our environment.

Having said that, biodegradable plastics are usually much more efficient and eco-friendly than normal plastic and help to reduce pollution. Often, companies that manufacture biodegradable products use renewable resources and so produce lower emissions.

Some good examples of biodegradable plastics are:

• Polylactic acid (PLA): It is made from renewable sources such as corn starch and decomposes well in the presence of acids. PLA can be used for grocery bags, food packaging, thermal insulation as well as medical applications like medical sutures and plates. However, it is only industrially compostable and can take between 6-12 months to degrade in soil.
• Polyhydroxyalkanoate (PHA): Blended with starch and cellulose, PHA is more economical and will biodegrade in ambient environment including the ocean. It can also decompose in soil, compost, or marine sediment.  
  
  

What is ‘Compostable’?

‘Compostable’ means products are capable of complete biodegradation in compost, meeting specific standards for breakdown to receive a compostability certification.

Compostable packaging is made from natural materials, and unlike some bioplastics, it can decompose fully without leaving behind any toxicity. Research has found that compostable products broke down or completely disappeared much quicker than biodegradable products that can still persist in the environment after three years.

Also, whereas flexible plastic packaging waste is often too contaminated with food waste to be suitable for recycling and ends up sent for incineration or to landfill, compostable packaging avoids this problem as the compost produced can return organic matter to the soil.

How to know if a package is compostable

To know for sure whether your package is compostable, look for a certified compostable logo as this would prove that the packaging can be broken down completely without any toxic residues. Any products labelled as ‘compostable’ are designed to degrade in a compost system with food waste. Including certified compostable items like takeaway containers, food packaging, cups, and plates.

There are two variations of compostable packaging which are industrial composting and home composting. These are identified using different packaging labels.

• Industrial composting: The products will show the ‘seedling’ logo and should not be thrown into home composts as they usually require different conditions to compost properly.
• Home composting: The home compostable logo is used to highlight products that can be disposed of in a regular home compost.

The difference between home, commercial and industrial composting

Certified compostable products must be disposed of in a designated municipal composting facility unless stated otherwise, as many certified compostable items require higher temperatures of industrial settings to biodegrade quick enough.

To be certified home compostable, the compostable materials must disintegrate within 18 days. Home composters have a lower mass and are generally exposed to ambient temperatures so under these conditions it will disintegrate within the time frame. However, commercial, and industrial composters have a much larger mass of organic material, with more heat being generated from industrial composters (45-60 Degrees Celsius) allowing biodegradation to accelerate.

Therefore, compostable materials should disintegrate within 90 days in commercial compost - half the time it would take in a home compost.

What is Oxo-degradable?

Oxo-degradable plastics are conventional polymers where specific bio-additives (such as starch) are added to traditional plastic (e.g., polystyrene, polyethylene, polypropylene) to break them down into small pieces. Some examples of oxo-degradable packaging include carrier bags, blister packaging, bottles, labels, and caps.

The Oxo-degradable ban

In recent years, oxo-degradable plastics have been marketed as a solution to soil and marine pollution. However, significant evidence from a range of academics, testing laboratories, trade associations and multiple other experts now suggests that oxo-degradable plastic packaging never fully biodegrades. This is because microorganisms do not recognise the synthetic monomers, so they do not digest them.

The evidence has created major concern as it means oxo-degradable plastics contribute to microplastic pollution which poses an environmental risk, particularly in the ocean. Some evidence also shows that this is the case for other plastic packaging with similar chemical additives, both organic and inorganic, that claim to have accelerated biodegradation, including enzyme-mediated degradable plastics.

Oxo-degradable plastics are said to be not suited for effective long-term reuse, recycling at scale or composting as it goes against the two core principals of circular economy: designing out waste and pollution and keeping products and materials in high-value use. The Ellen MacArthur foundation has published a ban on oxo-degradable packaging due to this and the Environmental Services Association also released a statement saying, “overwhelming scientific evidence, including research commissioned by DEFRA and the EU, has demonstrated beyond doubt that the claims these additives transform polyolefin plastics into biodegradable plastics are unfounded.”

Defining the difference

In conclusion, it is vital to recognise the distinctions between biodegradable, oxo-degradable and compostable as they have different implications for their end-of-life. It is possible to have fully functional, consumer-friendly compostable packages for all your packaging needs, including fresh produce, grains, snacks, apparel and even zipped bags for storage. However, not all biodegradable plastics are compostable so always look for the compostable certified logo on your packaging.

When it comes to oxo-degradable, we highly recommend to move to an actual sustainable packaging solution, considering the proven damaging affects oxo-degradable plastics have on our environment. If you would like to know what packaging solutions are available for you and your business, contact our packaging experts today.