Following the successful Kick-Off Event for the “Investigating New Forever Chemicals in Canadian Water Systems Project”, held in Spring 2023, a webinar was hosted by the Ontario Water Consortium (OWC) on June 20, 2024 to provide an opportunity to delve deeper into the progress and ongoing research in the detection and treatment of per- and polyfluoroalkyl substances (PFAS) in Canadian water systems. The webinar featured a series of insightful presentations from leading researchers and students involved in the project, highlighting significant advancements and future directions.
Funded by the NSERC Alliance Option 2 grant, the University of Waterloo and Western University have partnered with USP Technologies, Brown and Caldwell, Ontario Clean Water Agency, Ontario Water Consortium, and seven regional water supply systems in Ontario to address the presence of and treatment of PFAS in water supplies. The partnering facilities provide water and wastewater services to more than 2.5 million Canadians.
The webinar commenced with a welcome address from OWC, setting the stage for the session and reiterating the importance of tackling PFAS contamination in water systems.
PFAS in Canadian Water Systems
Professor Scott Hopkins from the University of Waterloo provided an overview of the NSERC Alliance project, which focuses on the detection and treatment of PFAS in Canadian water systems. He highlighted the collaborative efforts and innovative approaches being employed to address the challenges posed by these persistent environmental contaminants.
Professor Hopkins reported that, over the past year, the research team has made significant progress in detecting, quantifying, and treating PFAS in Canadian water systems, including water, wastewater, and biosolids. These man-made chemicals, known for their resistance to breakdown and environmental mobility, are a growing concern due to their prevalence and potential health impacts. Their work has involved developing advanced detection methods, exploring new treatment technologies, and applying machine learning models to optimize these processes. The team has collaborated with various partners and conducted extensive sampling to better understand PFAS concentrations and transformations during treatment.
The water treatment plant data shows relatively low PFAS concentrations, with PFAS levels remaining consistent before and after treatment, and PFOSA concentrations increasing during treatment. Key questions include the fate of transformation products, unknown PFAS, and other contaminants, as about 10,000 PFAS compounds are currently ignored.
Despite some success, challenges remain in detecting unknown PFAS and assessing the efficacy of treatment methods. To improve treatment outcomes and reduce PFAS contamination, upcoming efforts will involve new rounds of sampling, further development of treatment technologies, refinement of non-target analysis, and advancements in machine learning models.
Analytical Workflow Development
Emir Nazdrajic, a Postdoctoral Fellow at the University of Waterloo, presented on the development of analytical workflows for the quantitation and characterization of PFAS in both aqueous and solid samples. He discussed the technical challenges and solutions in accurately measuring PFAS concentrations, emphasizing the importance of robust analytical methods in understanding PFAS behavior in the environment.
Emir emphasized the importance of the project partners who provided complex samples for method development. The current EPA methods for PFAS analysis were improved by using specialized cartridges for carbon cleanup and optimizing chromatographic conditions. Initial findings indicate similar PFAS concentrations in influent and effluent water samples, but higher levels in wastewater. Challenges remain in analyzing biosolids due to matrix complexity. Future work will focus on refining high-resolution mass spectrometry workflows, accepting more samples for seasonal analysis, and enhancing untargeted analysis protocols.
Unmasking Trends in PFAS Classes
Chris Ryan, a MSc student at the University of Waterloo, introduced a novel analytical method that uses differential ion mobility (DMS) and liquid chromatography to characterize various chemical subclasses of PFAS. This two-dimensional separation technique allows for a more detailed understanding of PFAS composition and distribution, aiding in the development of targeted treatment strategies.
Chris emphasized the potential of DMS to identify unknown PFAS by distinguishing trends in various PFAS families, such as carboxylic acids and sulfonic acids. Future work includes applying this method to complex sample matrices, integrating it with EPA 1633 workflows for sample enrichment, and validating limits of quantitation (LOQs) to better detect PFAS in water and biosolids samples.
Thermal Treatment of Biosolids
Professor Franco Berruti from Western University discussed the scale-up of integrated drying, pyrolysis, and thermal oxidation technologies for the thermal treatment of PFAS-contaminated biosolids. Professor Berruti’s presentation focused on the practical aspects of implementing these technologies at a commercial scale, offering insights into their potential for widespread application.
The objectives of Professor Berruti’s team at Western include the destruction, reduction, and displacement of PFAS, producing valuable biochar for soil amendment, carbon sequestration, or adsorption applications. Research is also concentrating on thermal oxidation of vapors and gases formed during pyrolysis to break down carbon-fluorine bonds, and the subsequent mineralization of fluorine with metal oxides. Their pilot plant, “Le Bebe Chaud”, has shown significant PFAS reduction, achieving an overall reduction of 99.35%, with reductions between 93% and 99% observed throughout the entire system based on targeted analysis. The team is optimizing and scaling up this technology for industrial application. Key follow-up questions include how to implement this high-temperature pyrolysis process on an industrial scale.
Destroying PFAS and Capturing Synthetic Fluorine
Joshua Cullen, a PhD student at Western University, shared experimental work on the pyrolysis of PFAS-contaminated biosolids, coupled with thermal oxidation of vapors and gases. He also discussed the capture of fluorine through mineralization, presenting promising results that demonstrate the efficacy of these methods in breaking down PFAS compounds and capturing harmful byproducts.
His research highlights the effectiveness of thermal treatment in breaking carbon-fluorine bonds in PFAS, with pilot-scale testing showing a significant reduction of PFAS in biosolids at temperatures between 500 and 700 degrees. Target analysis revealed that less than 1% of initial fluorine remained as detectable PFAS in the biochar, and 17-25% remained in the bio-oil. Joshua’s work addresses the challenge of quantifying and capturing terminal PFAS by investigating two methods: thermal mineralization and metal mineralization. Testing with fluoropolymers and metal oxides (such as calcium, magnesium, and aluminum) demonstrated successful mineralization of fluorine, indicating potential for improved fluorine mass balance in pilot-scale systems. Joshua aims to apply these findings to industrial-scale processes and continues to explore in-situ metal oxide beds for thermal oxidizers to treat volatile PFAS byproducts.
Energy-Efficient PFAS Removal and Destruction
Ehsan Khorshidi Nazloo, a PhD student at Western University, introduced an integrated membrane-vacuum UV treatment system designed for energy-efficient PFAS removal and destruction in water. Nazloo’s pilot-scale study showcased the potential of this hybrid system to effectively treat contaminated water sources, offering a novel solution to the PFAS challenge.
Ehsan highlighted the challenges in treating PFAS, including the shift towards shorter-chain PFAS, incomplete mineralization, energy inefficiency, and evolving regulations. Current methods are insufficient and energy-intensive due to the strong carbon-fluorine bonds in PFAS. Ehsan’s hybrid treatment combines separation and degradation, using high-pressure membranes for concentration and vacuum ultraviolet lamps for degradation. This method targets contaminants in concentrated streams, improving efficiency and cost-effectiveness. Preliminary tests on pharmaceuticals showed significant degradation, and ongoing work aims to optimize parameters and apply the technology to actual PFAS samples, ensuring compliance with stricter future regulations.
Q&A and Discussion
The webinar concluded with a Q&A and discussion session facilitated by OWC, allowing stakeholders from across the water industry, including fellow academics, municipalities, provincial and federal government officials, consultants and industry representatives, to engage with the presenters and delve deeper into the technical details of their research.
Topics included the potential application of high-temperature processes for PFAS destruction in sewage sludge incinerators, with considerations on temperature thresholds and residence times. Questions also touched on cost assessments for treatment methods, prompting discussions on capital investments versus operational efficiencies, and the potential economic benefits of biochar production. Participants expressed interest in ongoing research and future developments in PFAS remediation technologies, emphasizing the need for cost-effective solutions aligned with evolving regulatory standards.
Overall, the webinar was a resounding success, highlighting the significant progress made in the fight against PFAS contamination in Canadian water systems. The event underscored the importance of continued research, collaboration, and innovation in developing effective solutions to protect public health and the environment from these persistent pollutants.