Surface area and environmental impact: what might it mean for extended producer responsibility and plastic pollution?
Something from my training as a surface scientist is (finally!) relevant to my current area of interest – i.e. the environmental impact of problematic wastes – and plastic waste in particular. This line of thought was partly prompted by a presentation I saw by WasteAid at a TechUK meeting last month on the impact of plastics in countries with little-to-no waste management infrastructure.
So why do I think we need to consider surface science and surface area? Surfaces are the interface between materials and their environment, and the smaller something is the higher its potential to interact and perturb its environment (per unit volume). For example, 1,000 1cm diameter pieces of plastic pollution are equivalent in volume to one 10cm diameter piece of plastic pollution but with 10,000 times the surface area interacting with the environment. Size matters – but not in the way most folk assume it does.
Most processes, be it raw material extraction and processing, product manufacture or EoL management, generally have a relatively consistently sized interface with the environment, i.e. roughly the size of the boundary of business premises (notwithstanding atmospheric and water emissions). This is probably why standard life cycle analysis (LCA) approaches work in the majority of cases. However, LCA’s do not seem to be capturing the true cost of poor EoL plastic management and the reason might be the orders of magnitude difference in the environmental interface of a globally dispersed and miniscule nature of plastic pollution compared to a single geographical site.
Leakage into the environment, through littering and a lack of infrastructure drive the dispersal of plastic waste. Estimates vary that there could well be over 250,000 tonnes of plastic in the worlds’ oceans. [Ref] 250,000 tonnes of ocean plastic is approximately 2.5X the annual capacity of the largest PET plastic recycler in the UK (Clean Tech), but with an environmental interface roughly 100 million times greater.
I appreciate that this is primarily a reflection on why plastic is such a big problem and not anything as useful as thoughts on how to tackle the problem. But using surface area as a metric might, in combination with other metrics, create a radically different list of wastes for future extended producer responsibility measures – and that is something we’re going to look into more.
Written by Nia Bell, Senior Consultant.
[Ref]: Eriksen M, Lebreton LCM, Carson HS, Thiel M, Moore CJ, et al. (2014) Plastic Pollution in the World’s Oceans: More than 5 Trillion Plastic Pieces Weighing over 250,000 Tons Afloat at Sea. PLoS ONE 9(12): e111913. doi:10.1371/ journal.pone.0111913