Plastics are indispensable in many areas of our lives, yet questions over the materials’ sustainability are often in the headlines. End-of-life plastic materials that can completely break down naturally and disappear harmlessly may sound ideal. People hear terms like “biodegradable”, “bioplastic” and “compostable” and assume that these plastics are more “environmentally-friendly”. However, the reality is not so simple.

The main issue here is a lack of understanding of the nature of compostable or biodegradable plastics and what bioplastics are, including specific applications and the specialist treatment process needed for these materials. Bioplastics are made using renewable feedstocks rather than being derived directly from oil, and can be used for producing polymers that can be recycled, like rPET, or biodegradable polymers such as PLA.

It may seem obvious that selecting bioplastics is a sustainable option. Although there is a benefit from not depleting a non-renewable source, many petrochemicals are a by-product of the oil refining process. While we still live in an economy that is reliant on oil, it may be better to make use of its by-products rather than let them go to waste. Bioplastics are not free from environmental impacts, and the CO₂ emissions associated with growing and converting crops into the required chemicals needs to be considered.

“Compostable” and “biodegradable” are synonymous terms and mean that the material will completely degrade under certain conditions. The key to understanding potential benefits is to know whether the polymer will easily break down, say in your home compost, or if it must be treated in an industrial composting facility. Many plastics described as biodegradable or compostable must be separated from the rest of plastics waste and sent to an industrial composting facility to be broken down successfully. These facilities exist for food waste, but ensuring compostable packaging reaches them can be challenging.

Consumer confusion over what materials can and cannot be recycled is another big issue. Is this water bottle made from a biodegradable or conventional plastic, like PET? Does it go in the recycling bin or food waste collection?

Currently, throughout the UK, there is good infrastructure for PET bottle collection and recycling, accessible through kerbside collections. The infrastructure for food waste collections is not as well established, especially for “on-the-go” products. For water bottles made from biodegradable plastic to be correctly recycled, a public campaign would be needed so people know that this plastic should go in with food waste.

Some packaging such as that made from starch will breakdown in a less controlled environment, but completely switching to these materials is not possible since they are not suitable for all applications. For example, kitchen/food starch-based bags will degrade in a home composting system, but would not be suitable for packaging use as this material breaks down when wet.

Brand owners, food producers and manufacturers need to carefully consider what packaging they use and make an informed decision based on the reality of current waste management infrastructure and level of public understanding. Ensuring that products are “designed for recycling” is essential, as is knowing what happens to materials at end-of-life and what the environmental impact could be.

So are biodegradable plastics better for the environment? It’s a massive challenge and complicated! Ultimately it has to be down to infrastructure investment, public education and behavioural changes. Plastics are an inherent part of our lives and not “all bad”. Responsible use and disposal/recycling should be a top priority!

Richard McKinlay
Head of circular economy at Axion