Formatted Title
PFAS in Suppression Systems: A Vehicle-Level Characterization of Persistent PFAS Impacts on Systems after Rinse
Background/Objectives
Per- and polyfluorinated alkyl substances (PFAS) in aqueous film-forming foams are under scrutiny as facilities react both to legislation mandating transition to PFAS-free firefighting formulations and public scrutiny of historical and current foam discharges. PFAS are known to aggregate at phase interfaces creating a water-resistant layer that can back-diffuse into PFAS-free firefighting formulations after changeout. The resistance of PFAS to removal from system surfaces during foam changeout has increased concern about the best method to minimize or eliminate PFAS risk. This project provides a by-part characterization of PFAS residuals on wetted surfaces of airport rescue and firefighting (ARFF) apparatus fire suppression system components following water rinse. The continuing presence of PFAS demonstrates the ineffectiveness of water to achieve complete PFAS removal and provides critical context to site stakeholders when determining the best course of action for reducing risk during transition to PFAS-free firefighting formulations.
Approach/Activities
This project provides a demonstration case study for the potential of full firefighting formulation delivery system replacement as a means for PFAS elimination from an ARFF apparatus. Metrics include replacement equipment costs, personnel effort required, and time from inception to completion are reviewed to determine the feasibility of a full replacement approach. Characterization of PFAS on the surfaces of the foam concentrate, water, and post-mixed foam system of an ARFF apparatus are presented. Characterization techniques include scanning electron microscopy, total organic fluorine, liquid chromatography with tandem mass spectrometry, total oxidizable precursor assay, particle-induced gamma emission spectroscopy and X-ray photoelectron spectroscopy. Data presented analyze the effect of system location, part orientation, and material of construction on PFAS surface residual loading after a triple water rinse.
Results/Lessons Learned
Results/Lessons Learned. There are indefinite and evolving regulatory criteria relating to firefighting foam use amidst multiple authorities transitioning away from PFAS. This project presents the process for full firefighting formulation delivery system replacement and the challenges faced that protracted the completion of the replacement which provides a cautionary tale for future practitioners. Data presented show the composite sample results for each step of a triple water rinse prior to disassembly and characterization, including unexpected PFAS impacts on the water-only portions of the ARFF apparatus. Characterization data provide a statistically relevant analysis of the effect of part location, material construction, and type on PFAS residual while demonstrating that the method of rinsing with water three times is insufficient to remove PFAS from system components despite its prevalent use in the industry.