While conventional wastewater treatment systems aren’t designed to handle PFAS, a research team at Toronto Metropolitan University (TMU) says biofilm-based treatment known as aerobic granular sludge is a promising method to remove the family of chemicals from wastewater.
As per- and polyfluoroalkyl substances (PFAS) continue to be found in everyday items like non-stick cookware, cosmetics, and food packaging, these persistent chemicals enter water systems through wastewater and runoff, where they accumulate in organisms and are linked to serious health risks, including cancer, immune suppression, and liver damage. But the TMU researchers say aerobic granular sludge (AGS) treatment can trap PFAS more effectively than traditional methods, even at high concentrations, without compromising the system’s ability to remove other pollutants.
Using AGS, microorganisms stick together and to surfaces, the TMU researchers say. Over 247 days, the team used AGS in two sequencing batch reactors to test synthetic wastewater containing PFAS compounds PFPeA, PFOA, PFBS, and PFDS at concentrations reaching 500 µg /L.
“Our findings suggest that AGS can play a key role as a frontline capture step, separating PFAS from the liquid stream early in the treatment process,” said Rania Hamza, co-founder of TMU’s Water Research and Resource Recovery (WR3) Urban Water Lab.
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Both reactors were able to achieve some 95% removal of chemical oxygen demand, ammonia, and phosphate.
Joined by TMU professors Roxana Suehring and Steven Liss, the research team simulated real-world PFAS concentrations based on global wastewater data. Even under heavy PFAS exposure, AGS maintained over 95% removal efficiency for ammonia and organic matter and retained PFAS up to 10 times more effectively than conventional systems — likely due to the granules’ dense, water-repelling structure.
“The most surprising outcome was not just the operational stability, but the clear indications that AGS can adapt and maintain treatment function under PFAS pressure,” said Hamza. “This opens new avenues for resilient, biofilm-based PFAS mitigation strategies.”
Once captured in the sludge, PFAS can then be destroyed using advanced methods like incineration or chemical decomposition, an approach that combines biological containment with targeted treatment.
The research, conducted at TMU’s WR3 Urban Water Lab and published in the Journal of Hazardous Materials, offers a scalable solution for municipalities. Since AGS is already in use for nutrient removal, it could be deployed for PFAS control without major infrastructure changes.
The study was supported by TMU’s Faculty of Engineering and Architectural Science, Urban Water TMU, the Natural Sciences and Engineering Research Council of Canada (NSERC), and the Canada Water Agency.
