The fate of compostable packaging in home composting systems

The convenience of single-use plastic is undeniable. Since the early 1940’s single-use plastic has increasingly replaced traditional coverings such as paper. In the not-so-distant past items were sold ‘loose’ with no plastic covering, but as our expectations have changed so have our acceptance of this ubiquitous commodity. While the carrier bag tax (UK) in 2015 encouraged the switch from free plastic to reusable bags, the use of single-use plastic as packaging is still heavily used. Most often reusing single-use plastic poses a challenge, due to being manufactured for just a single use it can easily fragment. In recent years alternatives to single-use plastic have started to emerge, claiming to do the same job of protecting perishable items, with the added bonus of breaking down naturally, therefore reducing the volume of plastic waste sent for disposal. These often more expensive alternatives can be robust and offer an attractive alternative to their single-use hydrocarbon-based cousins.

Compostable plastic alternatives can be more appealing since they claim to fully break down into their natural constituents of water, carbon dioxide and an organic component. However, the vocabulary of these new alternatives can be confusing as consumer awareness between degradable, biodegradable and compostable is often limited. Together with varied instructions to decompose these alternatives, many consumers are either extracting the slimy, often complete packaging, from their composting system and/or disposing directly into their home refuse waste for incineration or landfill. Confidence is dwindling and indeed recently some organisations have stopped using compostable packaging.

My research will start with surveying home/allotment composters to understand what composting methods are used, together with their experience, if any, of compostable packaging. The results of which will inform controlled laboratory experiments using modified Dynamic Respiration composting reactors designed to measure decomposition rates of compostable materials.

Later, using garden composting systems, a range of environmental parameters will be measured. Raman spectroscopy will be used to characterise the type, size, and stage of decomposition of compostable packaging. This research will help to inform future development of this new generation of plastic alternatives together with demystifying the confusion faced by consumers.