As Vancouver-based Axine Water Technologies reports some success in destroying per- and polyfluoroalkyl (PFAS) compounds in water and wastewater through electrochemical oxidation, the U.S.-based Water Environment Federation (WEF) has announced its own plan to study pyrolysis and thermal oxidation to also destroy what are often called “forever chemicals”.
Manufactured and used since the 1940s in a wide range of products worldwide, such as non-stick pans, cosmetics and firefighting foams, PFAS has also had numerous adverse impacts on the liver and kidney, as well as immunological effects.
Now, researchers are looking for the most effective ways to treat and destroy the compounds.
Axine’s EOx technology uses advanced catalysts and electricity to oxidize organic pollutants in wastewater to non-hazardous byproduct gases. According to the company, no toxic chemicals are required, and no solid waste is generated in the PFAS removal process.
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Axine said they successfully treated high PFAS concentration from 10 parts per million to under 100 parts per trillion, achieving nearly a 100% reduction.
“We’re very pleased with these results,” announced Axine’s VP of Technology, Victor Leung, in a statement. “They are consistent with the performance we’re achieving in the pharma industry where we routinely treat wastewater contaminated with non-biodegradable pharmaceuticals, including those that are fluorinated, to below analytical detection limits.”
Leung added that the technology may soon be a “reliable new standard for on-site PFAS destruction,” as opposed to removal offered by alternative extraction techniques that collect PFAS for hazardous disposal or secondary destruction, the company says.
The technology, however, was not as comprehensively effective in treating low initial PFAS concentrations.
WEF studying PFAS removal
As many utilities contemplate new ways to eliminate PFAS from biosolids to ensure regulatory compliance and to continue the many beneficial uses for the resource, WEF has partnered with a multidisciplinary research team to study the effectiveness of using pyrolysis followed by thermal oxidation to destroy PFAS.
Following an 18-month research period involving sampling, laboratory experiments, and analyses, a final report with findings and full-scale recommendations will be published by WEF.
“It is vital for economic and environmental sustainability that communities across the country are able to use biosolids for their many benefits and that this valuable resource is not just sent to fill up landfills,” said WEF Executive Director Walt Marlowe, in a statement. “The water sector has always used the best science to guide our work, and this research to explore destruction of PFAS is part of that commitment.”
The $500,000 study will be led by principal investigators Lloyd Winchell (Brown and Caldwell), Franco Berruti (Western University), and Detlef Knappe (North Carolina State University).
Pyrolysis — the chemical decomposition of organic materials via heat without the presence of oxygen — produces valuable biochar and fuel-rich off-gas. By using thermal oxidation, the off-gas can be reused as the heat source for pyrolysis or to generate power. In tandem, these processes can potentially destroy PFAS to alleviate concerns with biochar reuse or air emissions.
The research will evaluate PFAS destruction through a laboratory and full- scale pyrolysis and thermal oxidation system, including a mass balance to understand the fate of PFAS through the process.