A problem like PFAS: navigating regulation and research

While per-and poly-fluoroalkyl substances (PFAS) contamination is an issue the water community is acutely aware of, recent media coverage has peaked public attention, shining a spotlight on where Australia is positioned in terms of regulation and remediation efforts.

Known as ‘forever chemicals’ due to their resistance to degradation, PFAS have been used for decades in the manufacture of oil and grease-resistant food packaging, non-stick cookware, cosmetics, clothing, and fire-fighting foams.

While PFAS contamination of water and soil is now well-known by water professionals, Professor in the UNSW School of Civil and Environmental Engineering and Managing Director of the Water Research Laboratory, Denis O'Carroll said the heightened public perception of the issue underscores the need to continue monitoring efforts while solutions are developed.

“First and foremost, a lot of people are concerned about whether or not PFAS is in their tap water. There’s been a lot of media coverage recently,” he said.

“In my view, we are not poisoning our kids when we let them drink water from the tap. Do I think we should be paying attention to PFAS levels in drinking water and the environment? Yes, absolutely. We could be quantifying a broader range of PFAS and releasing that information.

“Some of our Australian utilities only report on three different varieties of PFAS, whereas in the US, European Union and Canada many more PFAS come under regulatory scrutiny. Just because they are not regulated in Australia doesn’t mean we shouldn’t check on them.

“The water sector is acutely aware of the PFAS issue. It’s not my role to direct water organisations, but I think it would be good for us all to keep an eye on international standards and to continue monitoring efforts.

“As water professionals, we pay attention to all contaminants, not to scare people but to be aware. We want to make sure we keep doing this to avoid further headaches in the future.”

O’Carroll said the fast-paced change in regulations creates a difficult context within which to steer public understanding of the issue, and even investment in new technology.

“Part of the issue is that regulation changes and it can change very quickly. It’s hard to navigate this issue, as their result can be that water providers end up taking heat for decisions that are made external to their influence,” he said.

“Or investing in new treatment technology that soon becomes outdated.

“In the broad range of chemicals I have worked with throughout my career, regulation around PFAS has changed at lightspeed. Usually things take time and it's a slow process. But PFAS is completely different.”

Current research focus

O’Carroll said removing PFAS in a drinking water system is costly, but absolutely possible: “We have removal methods that continue to be improved and we continue to build our understanding of remediation techniques”.

Researchers from UNSW’s School of Chemistry have designed a catalyst system that can activate a reaction to break down common types of branched PFAS. The new method developed by Dr Jun Sun and Professor Naresh Kumar holds promise for more efficient and sustainable PFAS remediation in the future.

Working alongside O’Carroll, and Professor Michael Manefield and Dr Matthew Lee, and funded by a $3 million grant from the Australian Research Council in 2019, the team have designed a catalyst system that could play a key role in solving the problem of PFAS.

“Owing to its robust nature, simple application, and cost effectiveness, the new system we have developed shows successful PFAS remediation in the lab, which we hope to eventually test at a larger scale,” Sun said.

The application of activated carbon which absorbs PFAS is an approach already established, but destroying the concentration of PFAS removed is an area of work that’s still developing.

“So if you’ve got a pad of activated carbon, and you pass water through it, you can absorb PFAS onto the activated carbon, but you then have to burn it to destroy the PFAS, or safely store it,” Kumar said.

Another method scientists have explored uses a strong oxidising agent to break PFAS down, but this approach can exacerbate the issue, creating more smaller structures that become even harder to remove completely.

“There is an ongoing need to come up with an energy efficient and environmentally friendly way to remove PFAS from water. The method we have developed is a type of reductive defluorination, which decreases the toxicity of PFAS by breaking the strong C-F bonds of branched PFAS,” Sun said.

Catalysing change

Nano zero-valent metals (nZVMs) are an eco-friendly chemical reducing agent used for decades in the treatment of groundwater and soil contaminated with chlorinated compounds, using a dechlorination process.

But there has been a lack of research into the defluorination of PFAS using nZVMs, largely due to the lack of appropriate catalysts required to activate the reaction.

“Inspired by the fact that B12 has the potential to catalyse this reaction, we wanted to synthesise a catalyst that mirrors the unique ring shape of B12, which we did using a structure known as a porphyrin ring,” Sun said.

Testing their method out on two common types of PFAS – branched PFOS and PFOA – Kumar and Sun mixed the PFAS chemicals with nZVMs and the porphyrin ring in a buffer solution and measured the breakdown of the PFAS.

"We did this by following how much fluoride is released as those strong carbon-fluoride bonds are broken down. So by simply measuring the amount of fluoride ion that is produced by the reaction, we can tell how much of the PFAS have been degraded,” Sun said.

“We also compared these results to the existing B12 catalysts and found that the cobalt porphyrin ring we have used was more efficient and faster at degrading branched PFAS.”

Results revealed that within five hours, approximately 75% of the fluoride had been released from branched PFOS and PFOA, significantly reducing the amount of PFAS within the solution.

Large scale application

While further research is required before this method can be applied at scale, the UNSW research team are focusing on next steps.

“The next step for us is to really try this on a pilot scale to see if this can be done out of the laboratory on a real sample. Then we’d like to try it out in a real water purification system or sites which are contaminated with PFAS,” Kumar said.

The team are also considering ways to scale up the process in an environmentally friendly way, by incorporating the catalyst into an electrode.

"These findings would allow us to set up the catalytic system in an electrochemical cell, where applied voltage can replace the nano zero-valent zinc so that the PFAS can be degraded within the cell,” Kumar said.

"We hope to try this method out on linear PFAS, not just branched types. But we’re already one step closer to solving a widespread environmental problem,” Sun said.