Emission of Per- and Polyfluoroalkyl Substances from a Waste-to-Energy PlantROccurrence in Ashes, Treated Process Water, and First Observation in Flue Gas

Per- and polyfluoroalkyl substances (PFASs) are a largegroup ofcompounds commonly used as industrial chemicals and constituents ofconsumer products, e.g., as surfactants and surface protectors. Whenproducts containing PFASs reach their end of life, some end up inwaste streams sent to waste-to-energy (WtE) plants. However, the fateof PFASs in WtE processes is largely unknown, as is their potentialto enter the environment via ash, gypsum, treated process water, andflue gas. This study forms part of a comprehensive investigation ofthe occurrence and distribution of PFASs in WtE residues. Samplingwas performed during incineration of two different waste mixes: normalmunicipal solid waste incineration (MSWI) and incineration of a wastemix with 5-8 wt % sewage sludge added to the MSWI (referredto as Sludge:MSWI). PFASs were identified in all examined residues,with short-chain (C4-C7) perfluorocarboxylic acids being themost abundant. Total levels of extractable PFASs were higher duringSludge:MSWI than during MSWI, with the total annual release estimatedto be 47 and 13 g, respectively. Furthermore, PFASs were detectedin flue gas for the first time (4.0-5.6 ng m(-3)). Our results demonstrate that some PFASs are not fully degradedby the high temperatures during WtE conversion and can be emittedfrom the plant via ash, gypsum, treated process water, and flue gas. Minimal research exists on the fate ofper- and polyfluoroalkylsubstances (PFASs) in waste-to-energy processes. This study, the firstof its kind, depicts a snapshot of the presence of PFASs in waste-to-energyresidues.