PFAS in Wastewater: Environmental Detection and Removal via Pyrolysis

The first 30 minute presentation will be given by Taryn McKnight on in-depth characterization of PFAS in wastewater using a more comprehensive analysis. Research and studies typically look for specific PFAS compounds. Employing the broader “total organic fluorine” assay allows for better assessment of PFAS and helps explain why individual PFAS concentrations may increase during conventional wastewater treatment. This presentation will highlight research on a variety of wastewater samples from private WWTPs, to POTWs and outfalls from an Industrial Pretreatment Program. Targeted analyses can only capture a few dozen PFAS constituents, so with a family of thousands of chemicals we may be missing the bulk of the picture. Emerging tools like Total Organic Fluorine and Total Oxidizable Precursor Assays are required to illuminate more of this hidden mass of PFAS and this research shows how much hidden mass may be present across these types of facilities.


The second 30 minute presentation will be given by Patrick McNamara and Zhongzhe Liu on fundamental research studies that investigated the impact of pyrolysis on PFAS from biosolids. Pyrolysis is a thermal decomposition process that occurs at high temperatures (normally over 450ºC) under limited or no oxygen. Pyrolysis of biosolids generates solid, liquid, and gaseous products. The solid product, called biochar, is a carbon-rich product similar to charcoal that can be used as a soil amendment because it retains moisture. The non-condensable gases produced, called py-gas, contain energy rich constituents such as methane and hydrogen. The py-liquid can be co-combusted as a fuel but can be problematic to the burner due to its corrosive and unstable properties. Current literature is contradictory on the impact of pyrolysis on PFAS, with removal and no removal of PFAS both being reported. Our new research confirmed that pyrolysis removes PFAS from the solid-phase biochar, but transformation products that were still categorized as PFAS were detected in the py-liquid. Thus, pyrolysis can be used as a technology to generate a value-added solid product in biochar that is PFAS free, but it is not a viable option to completely destroy PFAS.