Destruktion av per- och polyfluorerade alkylsubstanser (PFAS) vid förbränning i avfallsförbränningsanläggningar

Per- and polyfluorinated alkyl substances (PFAS) are a group of environmentally harmful chemicals. The group consists of more than 4730 different substances including two of the most famous ones; PFOA and PFOS. PFAS consist of carbon backbones connected to fluorine. They are in general thermally stable and persistent to degradation due to their C-F bonds, which is one of the strongest bonds in chemistry. The use of PFAS is widespread and therefore they can be found in a variety of consumer products, which eventually end up as waste. Household waste and other waste streams are incinerated at waste incineration facilities at (at least) 850° C for two seconds. The aim of this study was to investigate if that temperature is high enough to, at least partly, break down PFAS and to study where in the outflows PFAS ends up. Three different facilities (B2, P4 and P6) for waste incineration where examined, including incoming fuels; household waste, industrial waste, return fuel and sewage sludge. The three facilities included in the study had two types of boilers (grated and circulating fluidized bed) with three different treatment facilities for the flue gas and condensate. Bottom ash, fly ash, end product and condensate were analysed after incineration. A mass balance based on the limited amount of data indicates that at least 86-98 % of the 11 examined PFAS substances are eliminated. The difference between the three facilities are probably due to a difference in temperature and a few problems during the sample week. Another reason might be the variations in PFAS concentrations in incoming fuels. The facility with the lowest elimination percentage also had the lowest PFAS-concentrations in incoming fuels, and some problems during the sample period. The facility with the highest elimination percentage had a more even and higher temperature