Evaluation of PFAS concentrations at key stages of a waste-to-energy process

Per- and polyfluoroalkyl substances (PFAS) are widely present in consumer products, making waste streams a potential source of contamination to soil, groundwater, and air. Thermal degradation in Waste-to-Energy (WtE) plants is considered a promising approach to reduce these pollutants, yet emission data remain limited. The heterogeneous distribution of PFAS in waste, uncertainties in sampling and analysis further challenge effective management. We conducted a measurement campaign at a Swedish WtE facility equipped with an electrostatic precipitator for particle removal and a three-stage wet scrubber for acid gas control and heat recovery. Semi-volatile and volatile PFAS in flue gas were analysed using OTM-45 and OTM-50 methods, respectively. Additional samples of gypsum, sludge, effluent, scrubber water, and ash were collected to assess PFAS fate throughout the treatment system. Results show that nearly 70% of semi-volatile PFAS were removed during flue gas treatment, with only ∼1 ng Nm⁻³ detected at the stack. Short-chain PFAS (e.g., PFPrA, PFBA) occurred in liquid effluents at <5 ng L⁻¹, whereas heavier compounds such as PFOS and 6:2 FTS were effectively removed by the coagulation/precipitation unit. Several PFAS were also detected in field blanks using OTM-50, and numerous fluorinated gases were difficult to interpret, suggesting possible contamination from the surrounding atmosphere or sampling equipment. These findings provide new insights into PFAS behaviour in WtE plants and highlight the need for improved emission data and robust analytical protocols to support future regulatory frameworks.