Monday, September 9, 2024
11:00 AM - 11:30 AM
Location Name
Some Like It Hot, but PFAS Does Not! Advancing Thermal Destruction of PFAS in Biosolids

Many wastewater agencies in California are facing the dual challenge of trying to address PFAS within the treatment plant and facing limitations in biosolids disposal options. This presentation will address both of those challenges and give attendees a solid understanding of how PFAS enters wastewater, accumulates in biosolids, and different destruction techniques that are being evaluated. We will specifically discuss PFAS characterization studies that have been done to-date in California wastewater treatment plants, and new innovative studies where Brown and Caldwell (BC) is partnering with utilities to better understand PFAS destruction using thermal processes. This presentation will highlight recent work that is underway at Silicon Valley Clean Water (SVCW), which has the only operational large scale biosolids pyrolysis systems in the country. Because the fate of PFAS through pyrolysis is not well understood, BC has partnered with SVCW to perform special studies aiming to provide a comprehensive picture of the fate of different PFAS species, precursors, and transformation products through the biosolids pyrolysis processes. This work will provide valuable insights into the level of PFAS transformation and/or destruction within the pyrolysis system. Because thermal treatment is the only technology currently available to utilities to destroy PFAS, this research aimed to characterize the extent of destruction and support development of scientific data documenting their positive environmental impact. For this study, SVCW provided dewatered biosolids that were transferred to a laboratory partner at Western University’s Institute for Chemicals and Fuels from Alternative Resources (ICFAR) in London, Ontario. Dewatered biosolids were dried and processed through a bench scale pyrolysis reactor coupled with a thermal oxidizer, at operating conditions resembling SVCW’s process. Samples of the dewatered biosolids, dried biosolids, biochar, and gas emissions will be collected for PFAS analysis, including targeted, non-targeted, and total organic fluorine to fully characterize PFAS fate through the system. Results of this study will demonstrate whether current sampling and analytical approaches approximate a mass balance for specific compounds while identifying others previously unknown. Initial sampling to determine baseline PFAS concentrations has been completed.