The problem with the plastics problem
Solving the plastics problem will not be easy. It does not have one single and simple solution. The problem is complex and often underestimated. Single use plastics, exemplified by plastic packaging will, and should, never be eliminated completely - to do so would risk other undesirable environmental consequences.
Take the cucumber. With a plastic wrapper, they last for up to 11 days longer than without. This simple film of plastic thus helps to prevent food waste and reduces greenhouse gas emissions that are generated through additional deliveries and waste food degradation. What happens to that plastic wrapper is also important. How many end up the recycling bin? While the recycling of plastic milk bottles (made from HDPE) is one of the hidden success stories of the recycling industry with over 30% of every milk bottle made from recycled content, this relies on the consumer to responsibly recycle their bottles, and all local authorities to collect them. Here, it’s easy to see how consumers can be confused; different local authorities have different rules for what they will and won’t collect for recycling which can cause confusion and misunderstanding.
The problem is not just in single-use products. They rightly receive much scrutiny as a result of our drift into being a disposable society and much can and should be done to reduce the amount and complexity of what we use. However, packaging plastics only make up less than 40% of the total plastic waste generated. This means that the majority of plastics are made and used in other areas such as in homeware, textiles, construction, healthcare, automotive, electrical amongst others. What happens to these at the end of their life? While a reusable coffee cup or water bottle are improvements on their single use counterparts, they still reach an end of life when left on a train, dropped and broken etc.
Do the public think of these as plastic that can be recycled, does it end up in the recycling bin? What do we currently do with waste textiles, many of which are made from the same material as disposable water bottles?
Our recycling industry is very good at recovering plastics to create value, and second uses thereof. Polyester, commonly known as PET is widely mechanically recycled. It is noticeable through the darkened colour of the bottles - that results from impurities in the recycling process - on the shelves that the levels of recycled PET is increasing.
There is however a limit to how many times a plastic can be recycled through mechanical means before it has to be used for lower value applications on account of a loss of it’s properties. PET is now widely repurposed into fibres that are made into clothing. When that reaches the end of it’s life, some is captured and recycled further, often into even lower value fibres for carpets. But what happens when carpets reach the end of their life? Typically they will be sent to landfill or burnt for energy recovery.
While the extension of the lifespan of the plastic is excellent, it still pollutes our environment in the long run. Pyrolysis or solvolysis technologies (sometimes referred to as chemical recycling) are gaining traction as mature methods to reduce the plastics to small molecules but are still limited by either the purity of the feedstocks or the production of complex mixtures of products, often at a high energy cost.
Emerging technologies such as catalytic chemical recycling or upcycling present exciting technologies to recycle the unrecyclable and create value from these wastes streams without costing the earth.
So what is the solution? As outlined above, there isn’t one single solution. Important decisions about our future relationship with plastics need to be made. We need better public education about the benefits of plastics and the need to responsibly handle this precious resource. There needs to be consistent messaging on recyclability and collection at source (the home, the waste recycling sites, town centres etc.) which, coupled with best practice on product design will ensure that the maximum quality and quantity of recylate will be collected for processing. Where it is not possible or practical to collect and recycle (for example additives or agricultural materials) we may need to look at biodegradable solutions. Improvements to our recycling infrastructure will be required to deal with the increased volume of plastic waste that will be captured.
While mechanical recycling will likely remain as the first choice for value recovery, when the materials are devalued or too complex, other solutions such as catalytic chemical recycling and upcycling are needed to go beyond smarter packaging and realise zero plastic waste.
Andrew Dove, Professor of Chemistry.