POLY- AND PERFLUOROALKYL SUBSTANCES (PFAS) - CONTAMINATED FIRE PROTECTION TRAINING AREAS AND AVAILABLE SITE REMEDIATION TECHNOLOGIES

Per- and polyfluoroalkyl substances (PFAS) are a group of thousands of synthetic chemical compounds characterized by surfactant properties, water and oil repellency, high thermal stability, and chemical resistance. These characteristics have favored their widespread use in industrial and consumer products, such as firefighting foams, water-repellent fabrics, food packaging, and non-stick coatings. However, their high persistence, mobility, and tendency to bioaccumulate have led to widespread environmental contamination and increasing concern about potential risks to human health. The aim of this thesis is to provide an up-to-date overview of PFAS, examining their physicochemical properties, environmental behavior, international regulatory framework, and main remediation technologies. The acquired knowledge was applied to a case study concerning contamination from firefighting foams at the fire training area of Santa Maria Island airport (Azores, Portugal), with the objective of assessing the extent of contamination, consequences for human health, and identifying the most suitable remediation strategy, taking into account the site characteristics and logistical constraints of a remote island context. The methodology involved an in-depth review of the scientific literature, a sampling campaign for soil and groundwater at five points around the study area, and a two-tiered risk analysis. Tier 1 compared the measured concentrations with reference values available in the literature, while Tier 2 integrated site-specific parameters using the Risk-Based Corrective Action (RBCA) approach, implemented through the Risk-Net software, allowing for the definition of site-specific remediation targets. The results confirmed significant contamination due to decades of use of PFAS-containing firefighting foams. Tier 1 showed that reference values were exceeded in both soil and groundwater, making a second-level analysis necessary. Soil contamination was dominated by long-chain PFAS, particularly PFOS, which have a greater capacity for soil adsorption, whereas short-chain PFAS, more mobile and prone to migration, prevailed in groundwater. The second-level analysis provided a more realistic assessment of receptor exposure and highlighted the importance of using site-specific parameters for proper risk evaluation. Furthermore, the high concentrations detected indicated the need for further investigations to more precisely define the extent of contamination. The choice of remediation technology was based on a Multi-Criteria Decision Analysis (MCDA), evaluating effectiveness, cost, sustainability, and feasibility. High-temperature incineration with emission recirculation (Haemers Technologies) proved most suitable for soil, due to its ability to destroy PFAS, treat hydrocarbon co-contamination, and adapt to logistical constraints. For groundwater, a Pump and Treat system with activated carbon or ion exchange resins and a hydraulic barrier is proposed, while capping the area would allow training activities to continue. Overall, the thesis shows that managing PFAS-contaminated sites requires an integrated approach, considering risk, site-specific characteristics, contaminant behavior, and intervention feasibility, highlighting the challenges posed by regulatory limits and remote geographic contexts.