PFAS is the latest in a long line of public and environmental health panics, and a particularly insidious one. But these invisible, ‘indestructible’ toxic compounds might have met their match.
Birmingham is no stranger to breaking new ground and pushing boundaries. Known as the City of 1000 Trades in the early-Industrial Revolution, by the year 2000 around 2,800 of the UK’s 4,000 annually copyrighted inventions were born within a 35-mile radius of the Midlands metropole. The rate of innovation hasn’t stopped since, and one of the latest eureka moments could be a global game-changer.
If you’re new to PFAS then evidently you don’t read Environment Journal enough. Colloquially known as ‘forever chemicals’, the term refers to a vast appendix of compounds which are used for an equally expansive number of tasks. From the mundane and everyday to highly specialised applications. The big problem is, many of these substances do not naturally break down in the wild, and those that do can take millennia to disappear.
This means over time concentrations accumulate where PFAS enter the environment. And from there they leach, spread and disperse to other locations, eventually winding up in our food chain and our bodies. Finding a solution to this mounting waste issue is now considered one of the most pressing environmental challenges.
Enter a team of researchers at the University of Birmingham who last month finished as finalists in the RSC Emerging Technologies Competition. Their work centres on a process, and machine, that could offer a vital lifeline by allowing us to easily breakdown and destroy PFAS at source. Dr Dominik Kubicki, Associate Professor of Chemistry, can explain more.
‘The RSC recognised a technology that does not merely remove PFAS and move them elsewhere. It destroys their carbon-fluorine framework and opens a route to recover fluorine, turning a persistent waste problem into the start of a circular materials system,’ he tells us. ‘We combine concentrated PFAS waste with a reactive metal inside a sealed ball mill. Impacts from the milling ball drive a room-temperature, solvent-free reaction that breaks the exceptionally strong carbon-fluorine bonds. This produces carbon and an environmentally benign mineral fluoride where the PFAS is then transformed into a non-hazardous material.
‘The residual waste is a stable mixture of carbon and calcium fluoride, CaF2. Calcium fluoride occurs naturally as the mineral fluorite,’ he continues. ‘Once it meets the relevant specifications, the material can be disposed of safely, [but] the more valuable route is to recover and use it. CaF2 is the starting feedstock for the fluorine industry, so PFAS waste could return fluorine to chemical manufacture as a controlled mineral resource.’
Dr Dominik Kubicki, Associate Professor of Chemistry at the University of Birmingham
There is, of course, a big difference between a controlled laboratory environment and the real world. More so, the budgets available for limited experiments and actual affordability to scale things up. According to Kubicki, these factors have already been taken into consideration: the reaction is not only easily replicated in a cost-effective way, it could be applied in a broad range of settings and scenarios.
‘The machine can be scaled and re-sized for each project. A benchtop unit processing hundreds of grams would occupy about 0.5 metres by 0.5 metres, similar to a desktop printer. A kilogram-scale pilot could be pallet-sized, roughly 1-2 metres square. At tonne scale, feed handling, containment and product recovery would make it a containerised or fixed plant, occupying tens of square metres,’ he replies when we ask about cost and the ability to implement in different places.
‘Small units could travel to stockpiles while larger units could be located at treatment or manufacturing sites,’ Kubicki continues. ‘Ball mills are familiar to industry as they already operate at enormous scale in cement, minerals, pharmaceuticals and battery materials. It is too early to quote a commercial price, but room-temperature, solvent-free operation and mature machinery give us a strong basis for competitive costs.’
Hopes are now high that the solution can be brought to the commercial market within six-to-12 months, although there are still challenges ahead. These include ‘demonstrating the process remains safe, repeatable and efficient’, although we’re told the remaining steps are standard for any engineering validation. Sadly, though, as Kubicki is quick to emphasise, the machine and process can only tackle one part of the wider PFAS problem. But there are already ways of handling the flip side.
‘Our system is designed for concentrated PFAS waste, such as solid fluoropolymers — PTFE, PVDF etcetera — and stockpiled firefighting foam concentrates. It is not suited for extremely dilute PFAS in water or soil. In those cases, the PFAS can first be extracted and concentrated, and the concentrated stream then sent to our process,’ he tells us. ‘Fluid-phase approaches are well matched and important to very dilute PFAS streams. Our process addresses the other end of the problem: it takes solid concentrated PFAS waste and directly transforms it into safe products with no solvent or heating necessary. The market needs complementary technologies matched to the concentration and form of each waste stream.’
All images: University of Birmingham
More on PFAS:
The Solent food web is riddled with PFAS, new research finds