Competition to destroy ‘forever chemicals’ heats up

In brief

In the face of looming regulations  and growing liability risks, companies are seeking help in managing waste containing per- and polyfluoroalkyl substances (PFAS), also known as “forever chemicals.” Dozens of start-ups are hoping to assist by supplying new technologies capable of destroying the carbon-fluorine bond. Once thought to be impossible to degrade, PFAS are proving to be no match for powerful techniques like electrochemical oxidation and supercritical water oxidation. Companies are also demonstrating that emerging technologies for PFAS destruction, like those that rely on the subcritical process hydrothermal alkaline treatment, plasma, ultraviolet light combined with photocatalysts, and sonolysis can break apart PFAS. When combined with technologies that concentrate PFAS on the front end, destruction technologies could provide a cost-effective way to eliminate PFAS in the environment and stop them from ending up in drinking water.

Scientists once wrongly assumed that the carbon-fluorine bond was almost impossible to break. And that meant there was no practical way to completely destroy per- and polyfluoroalkyl substances (PFAS).

PFAS contamination by the numbers

715

Number of US military sites that the Department of Defense is evaluating for potential contamination by per- and polyfluoroalkyl substances (PFAS)

~3,000

Number of open landfills in the US generating leachate containing PFAS

Nearly 12,000

Number of closed landfills in the US generating leachate containing PFAS

~65,000

Number of public water systems that will have to comply with US Environmental Protection Agency limits for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) proposed last year

4 parts per trillion

Limit proposed by the EPA for PFOA and PFOS in drinking water

$10.3 billion

Amount to be paid by 3M under a proposed settlement of a lawsuit filed by public water utilities over PFOA and PFOS contamination.

“They were truly thought to be ‘forever chemicals,’ ” says Julie Bliss Mullen, who began investigating technologies for removing PFAS from drinking water as an undergraduate in 2010. At the time, “destruction was not really on the table,” she recalls.

But Mullen was obsessed with breaking the carbon-fluorine bond. PFAS can be removed from water, but they just get transferred to another medium and eventually make their way back into the environment, she says. To stop that cycle, you have to destroy the molecules by breaking the “unbreakable” bond.

Around 2014, as a PhD student at the University of Massachusetts Amherst, Mullen got her hands on some electrodes and, as she puts it, “started playing around with electrochemical oxidation in the lab.” The process creates hydroxyl radicals and, unlike other advanced oxidation techniques, facilitates the direct transfer of electrons. “Those electrons will almost immediately break the carbon-fluorine bond if we’re able to get PFAS onto the anode surface,” she says.

Mullen won’t say how she attracts PFAS to the anode surface. But in 2017, she and the university filed for a patent and spun out a company, Aclarity, to commercialize the technology. Mullen never did finish her PhD. Today, as cofounder and CEO of the Massachusetts-based firm, she’s seeing big interest in the technology from landfill operators and wastewater treatment plants.

Aclarity is not the only company vying for a piece of the PFAS destruction market. Dozens of start-ups are working on technologies for destroying the chemicals, which have been linked to cancer and adverse effects on the liver and immune system. Some companies are already operating at full scale; others are not far behind. And it turns out that electrochemical oxidation is just one of many ways to break the carbon​-fluorine bond.

Companies are developing an array of approaches, including supercritical water oxidation, hydrothermal alkaline treatment, plasma destruction, ultraviolet light combined with photocatalysts, and sonolysis. They all claim to break down most PFAS into less harmful chemicals, such as carbon dioxide, fluoride ions, and water. But complete destruction of all PFAS, including short-chain PFAS and precursors, is a stretch for some techniques.

Many of these start-ups are partnering with companies specializing in technologies that remove PFAS from contaminated water and concentrate it. The PFAS destruction start-ups come in at the end and destroy the concentrated PFAS.

It’s early days for PFAS destruction and too soon to tell which technologies will succeed in the marketplace. But entrepreneurs who started these companies see the possibility of permanently ridding drinking water of the once-invincible “forever chemicals.”

Credit: Aclarity

Aclarity’s Octa system contains eight reactors that destroy per- and polyfluoroalkyl substances in water by electrochemical oxidation.

Electrochemical oxidation comes of age

Aclarity is one of a handful of companies developing electrochemical oxidation for destroying PFAS. The technique, one of the more mature on the market, works by applying an electric current through a conductive liquid between an anode and a cathode. Direct oxidation occurs at the anode surface after the transfer of electrons from PFAS. Indirect oxidation involves the creation of oxidants, such as hydroxyl radicals, that break PFAS apart.

Electrochemical oxidation techniques can destroy over 99% of long-chain PFAS, which contain eight or more fully fluorinated carbons. But destroying shorter-chain PFAS, which can be present initially or be created by the incomplete degradation of long-chain PFAS, is more challenging. Several companies claim they have optimized their technologies to destroy all PFAS, but they tend to be short on details.

Supercritical water oxidation takes the stage

Credit: Revive Environmental/Photo by Kimberly Rottmayer, Picture the Love

Kamanu Loo, director of operations and technology at Revive Environmental, removes the heat exchanger feed tube in a per- and polyfluoroalkyl substances Annihilator unit for cleaning and inspection.

Sprawling along the Olentangy River, the immense Battelle Memorial Institute campus in Columbus, Ohio, could easily be mistaken for part of the Ohio State University, which sits across the street.

The heavily secured main entrance to the nonprofit research organization’s headquarters leads to a colorfully lit lobby that looks like a cross between a museum and a fancy hotel. A series of underground hallways connects the nearly 100-year-old buildings.

Inside, a Battelle spin-off named Revive Environmental is preparing to deploy a technology called the PFAS Annihilator. Battelle, in partnership with Viking Global Investors, launched Revive a little over a year ago to commercialize supercritical water oxidation (SCWO) for PFAS destruction. SCWO is a powerful oxidation technique that obliterates organic chemicals. Scientists have been using it for decades to destroy chemical weapons and other difficult-to-treat contaminants.

Each Annihilator system contains a series of wires, heat exchangers, flow valves, pumps, and pipes connected to a reactor box that looks somewhat like a coffin. PFAS-contaminated water is pumped through the reactor, where high temperature and high pressure, above the critical point of water, enable an oxidation reaction that breaks the carbon​-fluorine bond.

Revive and a few other firms pursuing SCWO offer full-scale, commercial systems that can be integrated into existing wastewater treatment facilities or transported in shipping containers to contaminated sites. Each company is targeting specific markets and developing ways to lower energy use, control corrosion, and eliminate the buildup of salts that commonly clog SCWO systems.

Energy is a big part of the operating cost. SCWO works by heating and compressing liquid waste to above 374 °C and 22 MPa, the critical point of water. In that supercritical state, an oxidizer drives a reaction that cleaves the carbon-fluorine bond.

Credit: Revive Environmental/photo by Kimberly Rottmayer, Picture the Love

Taylor Cochran, a chemical process engineer at Revive Environmental, takes a clean, liquid sample as it exits the PFAS Annihilator processing unit.

Unlike some other destruction methods, SCWO does not create unwanted by-products, such as short-chain PFAS and precursors to PFAS. But in general, breaking the carbon-fluorine bond creates hydrofluoric acid, which has to be neutralized with a base like sodium hydroxide.

Battelle began developing the SCWO technology behind Revive in 2018. At the time, the organization committed nearly 100 staffers to destroying PFAS, says Amy Dindal, PFAS program manager at Battelle. “We set out with this more holistic view. Destruction was number 1, but we wanted to be able to augment that with other technologies and capabilities,” she says. These included accredited analytical methods for measuring specific PFAS, methods that screen for PFAS using high-resolution mass spectrometry, and a total organic fluorine assay used to verify that all PFAS are destroyed.

Related: Podcast: Can ‘forever chemicals’ be destroyed?

Battelle kept its analytical chemistry capabilities related to PFAS and now subcontracts those capabilities to Revive. Battelle also manufactures all the equipment and provides warehouse-size space for the start-up at its Columbus campus.

So far, Revive has installed a commercial PFAS Annihilator unit at a wastewater treatment facility in Michigan. But for PFAS destruction firms like Revive, “the hottest market right now is AFFF—aqueous film-forming foam,” says David Trueba, Revive’s CEO.

Our mission is to end PFAS, not to beat the other guys who are ending PFAS.

Nigel Sharp,  CEO and cofounder, Aquagga

AFFF is the firefighting foam used by military bases, airports, and anywhere there’s a need to extinguish flammable liquid fires, such as those caused by oil and gas. The US Department of Defense and state agencies are transitioning to alternative firefighting foams that don’t contain PFAS, and they are seeking to destroy stockpiles of unused AFFF.

States are aggregating AFFF from fire departments. “We just were awarded the Ohio State take-back program,” which will involve destroying PFAS in nearly 200,000 L of AFFF over the next few months, Trueba says. Revive is also working with New Hampshire and a few other states, as well as airports, to destroy AFFF stockpiles. Trueba predicts that eliminating all the stockpiled AFFF will take at least 5 years.

Chemical manufacturers, the oil and gas industry, and industrial users of PFAS are the next big market for SCWO, Trueba says. Some companies are trying to eliminate AFFF, some are remediating groundwater, and others with fluorinated chemical production processes are seeking a remediation step that will allow them to stay in business, he says.

Credit: Aquagga

Aquagga demonstrates its hydrothermal alkaline treatment system for destroying per- and polyfluoroalkyl substances at a remote site in Alaska.

Here comes hydrothermal alkaline treatment

Hydrothermal alkaline treatment (HALT), like SCWO, was developed decades ago to destroy stockpiles of chemical weapons. It too recently hit the PFAS destruction scene.

Automated Monoclonal Antibody Subunit Analysis

by Agilent Technologies

Timothy Strathmann, a professor of civil and environmental engineering at the Colorado School of Mines, and colleagues were the first to optimize it for destroying PFAS. The Washington State–based start-up Aquagga has an exclusive license to the technology and is commercializing it at full scale.

HALT is like SCWO but with a catalyst and lower temperatures, says Brian Pinkard, Aquagga’s cofounder and chief technology officer. The firm’s system operates at about 350 °C, in the subcritical phase, he says. In addition to using less energy than SCWO, HALT can handle high levels of salts without any special treatment, he points out.

Pinkard says the first time he heard about PFAS was in 2019, when he joined entrepreneur Nigel Sharp in the Innovation Corps program of the US National Science Foundation (NSF). The program trains scientists and engineers on how to explore the commercial potential of technologies they are working on in the laboratory.

At the time, Pinkard was finishing up a PhD at the University of Washington, where he was investigating HALT for destroying chemical weapons. “I was curious whether what I was working on had any commercial relevance to anybody anywhere,” he says.

Pinkard entered the NSF program thinking he might have a technology that could destroy sewage sludge, solving wastewater issues around the world, he recalls. But when he and Sharp started interviewing people in the wastewater and environmental industries, PFAS came up over and over again.

We’re the caboose of the treatment train. As long as you provide us with high-enough PFAS waste, we’ll hit it with a heavy hammer.

Daniel Cho, CEO and founder, Onvector

“We kept hearing, ‘PFAS is this huge issue. Nobody knows how to deal with this stuff. Nobody knows how to destroy PFAS. It’s an impossible problem,’ ” Pinkard says. “It turned out the technology that I was working on was applicable for destroying PFAS.” Pinkard, Sharp, and their colleague Chris Woodruff launched Aquagga later in 2019 as a public benefit company.

The start-up conducted its first field test last summer at an airport in Fairbanks, Alaska. The site has a lined pond that collected runoff for decades from PFAS-laden foam used in firefighting training.

Aquagga teamed up with ECT2 (Emerging Compounds Treatment Technologies), a Maine-based start-up that specializes in PFAS removal techniques. Aquagga used ECT2’s foam fractionation method, which concentrates PFAS and reduces the volume of liquid that needs to be treated. The team successfully destroyed PFAS in the concentrate with a mobile HALT unit.

The field test showed the technology can run off a generator at a remote site. “You can hook it up to these totes filled with really nasty water, process the water through it, and produce something that’s much, much cleaner for discharge,” Pinkard says. The system can process about a full tote’s worth of water in a little over a day, he says. That’s a bit more than 1,000 L.

Plasma sparks interest

The start-up Onvector is pilot testing what it calls a plasma vortex. The technology rapidly destroys long-chain PFAS, such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). But it takes longer for plasma to degrade short-chain PFAS, CEO and founder Daniel Cho says.

Credit: Britt Erickson/C&EN

Onvector’s plasma vortex breaks down per- and polyfluoroalkyl substances in a column of fire and lightning.

Onvector started out in 2013 in an industrial park on the outskirts of Philadelphia. The company’s main location is now nestled among other cleantech startups at the Greentown Labs incubator in Somerville, Massachusetts.

Scientists still conduct bench-scale tests in a small lab at the Pennsylvania site. A unit there, small enough to fit inside a shipping container, sits on metal scaffolding on wheels. Pipes, tubes, pumps, and valves connect PFAS-laden wastewater in a stainless steel tank to a plasma reactor housed inside a series of clear, block-shaped polycarbonate modules.

Argon gas is injected through an electrode in the bottom of the reactor. With the flick of a switch, a roaring flame appears inside.

The geometry of the reactor is similar to that of a cyclone separator used in industry to remove particles from a gas or a liquid, Cho says. “We’ve added an electrode at the bottom of the cyclone, through which we inject gas,” he says. The electrode generates high-energy electrons that ionize the gas, creating a plasma that stretches through the cyclone.

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Taxonomy

• PFAS