Destroying PFAS… and environmental anxiety

Luke Henderson talks to Adam Duckett about his work scaling up a plasma torch system to destroy PFAS

“I’M REALLY sorry to do this,” the email begins, and I groan. It’s not unusual for an interviewee to get cold feet and back out at the 11th hour but I hadn’t expected it for this one. And then relief: “We’ll be running some tests until fairly late tonight that we’ll be coordinating with some overseas business partners.” Thankfully, Luke Henderson only wants to postpone the interview until the following day. Perfectly reasonable, and perhaps the tests will give us more to talk about?

While planning this PFAS special we knew it would provide a broad sweep of the denser technical detail about remediation and destruction. To balance this, we wanted to include some personal insight by profiling an engineer working to help achieve that.

Luke works as an innovation engineer at Synergen Met in Australia. I tell him it’s a neat job title but it’s not one the 29-year-old is fond of.

“There’s a great deal of engineering positions of any variety around the globe that could have some credibility to claim themselves as innovation engineers. I don’t think I’m any more entitled to that little moniker than anyone else. It’s very much a chemical engineering position.”

Breaking down, building up

Luke is currently focused on testing a thermal plasma torch for a PFAS destruction plant that Synergen Met is commissioning. That’s what the previous day’s postponement was all about. The team are pushing to finish a skid-mounted process for shipment overseas to a contaminated site. This will allow the client to conduct a test run aimed at destroying a large amount of PFAS contamination.

It turns out there’s some symmetry here when we trace Luke’s path from his chemical engineering studies and doctorate involving thermal plasma processes at the University of Queensland to his work today.

“I did my work experience training with Synergen Met decommissioning a system very similar to the one I’m working on building now.

“It was mostly physical labour in the Brisbane summer sun, taking apart an acetylene production skid piece by piece.”

Luke had an intuition that he’d end up working for the firm.

“I always found the work really interesting, and here are these very intelligent people passionately working to solve real problems. I was hoping I would end up in that direction.”

It was Luke’s chance reading of a job advert that crystallised the opportunity.

“I was working for a water treatment startup and I came across an advertised position working on synthesis of chemicals with thermal plasma, and I thought ‘Hey, this is something I have very, very specific experience in. I think I might be able to bring something to this.’ I scroll down the advert and there I [see the position is at Synergen Met] so sure as heck I’m pretty happy to end up here.”

High stakes, high temperatures

As wider public consciousness grows about PFAS, I ask Luke if he can remember when he first learned about its impact.

“I don’t have a eureka moment sitting under tree and an apple falling on my head, but I can almost guarantee my first thought would have been ‘Oh God, something else to worry about’.”

“There are plenty of environmental problems in the world and this is one that is very solvable. It’s very high stakes as well, obviously, but it’s definitely solvable, and that gives me a lot of hope.

“Plenty of work has been done ensuring that this technology 100% does the job of destroying PFAS. A lot of the papers you’d find about PFAS destruction via thermal plasma would use maybe 10 kilowatt systems. Whereas the system we’re working on right now uses a 100 kilowatt plasma torch.”

I ask Luke to explain what the testing process looks like.

“A thermal plasma torch is a fairly simple concept for people to get their head around. I think of it as a giant toaster to some degree,” Luke says.

The arc that forms between the two electrodes is like the heating elements in your toaster but rather than adding bread there’s a continuous stream of gas that gets heated.

The PFAS you want to destroy are injected into the resulting plasma jet flame. Though the recent tests have not involved PFAS, the team is focused on control.

“When you’re working with a piece of equipment that can work at 10,000K, there have to be a lot of safety measures in place. Most of these are interlocks on the programming side. If any conditions deviate even a little bit from the norm, then the plasma torch needs to shut off right away.”

The testing setup pictured above shows the cylindrical torch (left, middle) bolted to a frame.

“When we test it, you see the jet of flame…a bright pink flame from one end of the torch that’s reaching 10,000 degrees at its hottest point. Of course, we’re not standing anywhere near it.

Instead, the team will located by the electrical cabinets (pictured in the background, behind the torch) manipulating the control systems.

“Any chemical engineer has seen pumps and heat exchangers 100 times, but the torch is really where it’s at.

“It’s a piece of technology that a lot of people don’t have that direct experience with. It poses challenges separate to a lot of the other standard reactors that one might deal with. The sheer fact that it produces temperatures in excess of 10,000°C means it’s very difficult to get a clear picture of what’s going on. We can’t very well just poke a temperature sensor in there because like anything else, it will melt. Even the design of the reactor, controlling the water-cooling system is so important because if something goes wrong, part of the torch melts very quickly.”

If something does go wrong, its disruptive, as it can take a long time to diagnose problems or procure replacement parts.

“It’s not like we have a lot of suppliers in Brisbane selling electrodes for a plasma torch.”

After the excitement of the plasma torch testing, Luke says the next couple of days will be less dramatic as he works on the detailed design and equipment sizing needed to fit the plant into the skid.

As for the future, he says his personal ambitions are tied up with Synergen Met’s success and the opportunity to help contribute to solving a serious social challenge.

“The technology that we’re working on right now is my number one ambition. It really is,” he says.

“On a very personal level, I don’t know if this is a very specific or a particularly universal thing, but I know there are lots of people out there who would be in a similar boat as me with anxiety about the state of the world, and particularly with the environment. I especially think this is relevant of young people. I think something that goes a long way to dealing with that anxiety is actually being in a position to do something about it.”