- [Frank Graff] This is a two story tall furnace with a big name.

- So this system here is a down-fired thermal oxidizer.

- [Frank] And that big furnace with the big name has one job: burn up dangerous chemicals.

- It basically simulates an industrial process for destroying hazardous or difficult to destroy compounds.

- [Frank] Those dangerous and hard-to-destroy compounds are PFAS, per and polyfluoroalkyl substances.

They're called forever chemicals, because they last forever.

The secret is in the chemistry.

- PFAS have the common attribute of having a carbon fluorine bond, and that bond is the strongest possible bond that carbon can have.

And so to break that bond, you have to have tremendous energy.

And frequently, that energy comes in the form of heat.

And that's exactly what we're studying here.

We're applying tremendous energy to the PFAS chemicals in the form of heat to break the bonds.

- [Frank] That super strong carbon fluorine bond is what made PFAS chemicals so useful.

They made life better, and that's why they're found everywhere: Waterproofing non-stick surfaces, firefighting foam.

Let's focus on that foam a little more.

- So this here is a small sample of aqueous film forming foam, and it's basically a liquid mixture of concentrated PFAS molecules.

Mixed with water and then sprayed on and it foams so much that it actually coats the fire and prevents oxygen from reaching the fire.

So this is an example of a perfluorobutanoic acid and it's one example molecule that would be found in many AFFF, or aqueous film-forming foam mixtures.

- [Frank] Trouble is those really useful chemicals are also toxic.

PFAS chemicals have been linked to multiple health issues, including cancer.

And those molecular bonds that made PFAS chemicals so useful are also what keep them from breaking down in the environment.

Remember that forever chemical nickname?

PFAS chemicals have been found in everything from the water supply to us.

It's a chemical conundrum, toxic mixtures found everywhere not breaking down.

The challenge is how to destroy them.

And that's where the rainbow furnace comes in.

- [Scientist] We're trying to understand what conditions result in full destruction of all of the fluorine contained in it.

- [Frank] Temperatures in the furnace range from 1,000 to 2,000 degrees Fahrenheit.

Different color levels, different temperatures.

- Our burner is up top, and as you come down from the burner it gets cooler.

And so in these ports in the side, we have these high temperature thermocouples that we use to continuously measure the temperature in each zone.

- [Frank] Researchers are learning what temperatures and conditions are best for destroying PFAS.

- We use this dual fluid atomizer and basically this gets introduced into a port on the side of the rainbow furnace.

And out of the tip here, we spray a mist of AFFF or other PFAS containing liquid.

So we can very precisely determine how much of the liquid we're injecting.

In order to know, ascribe a number like 99.9% destruction, you have to know exactly how much entered the system.

So in incineration we like to talk about the three Ts.

It's time, temperature, and turbulence.

You basically have to have enough time for everything to come up to temperature.

You have to have enough turbulence for everything to sufficiently mix and actually reach the temperature.

And then you have to have everything reach whatever the required temperature is to break all the carbon fluorine bonds.

If any of those three attributes are insufficient, you can end up with products of incomplete destruction, which are essentially fragments of the original PFAS molecule that you started with.

- [Frank] Those PFAS chemicals that aren't destroyed could be as toxic as the original compounds.

- I like to think of it as like a Lego set.

If you build a big Lego set every, you know what that is.

But if you come along and hit it with a sledgehammer or a bunch of heat, it breaks up into a bunch of pieces.

You might not recognize it as the set that you built, but you're still gonna recognize it as a bunch of Lego bits.

- [Frank] And there's also a concern about the gases that are released during incineration.

That smoke or vapor could also be toxic.

Scientists capture it for testing.

- And those samples would be pulled into these canisters, whatever's in the stack or in the emission source would come out into this can.

Then we'd bring them over to a lab, and they can be analyzed with gas chromatography, which separates those gases out according to their physical and chemical properties.

- [Frank] Researchers hope their work will provide guidance on how to destroy large quantities of PFAS chemicals.

- PFAS are in a lot of different things and a lot of different materials and can come off of those in a lot of different ways.

So we're trying to answer that question of, how do you measure it and where is it?

We're doing the research part of it.

We have communities that are interested in knowing whether they're safe or not.

We have states and local agencies that are clamoring to know what they need to do to keep their citizens safe.

And then we have our partners here in the federal agency that are gonna look at what policies need to be set, what guidelines, what rules or regulations and all.

So our information will feed into all of that.

[pensive music]