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

Abstract

Per- and polyfluoroalkyl substances (PFASs) are a large group of compounds commonly used as industrial chemicals and constituents of consumer products, e.g., as surfactants and surface protectors. When products containing PFASs reach their end of life, some end up in waste streams sent to waste-to-energy (WtE) plants. However, the fate of PFASs in WtE processes is largely unknown, as is their potential to enter the environment via ash, gypsum, treated process water, and flue gas. This study forms part of a comprehensive investigation of the occurrence and distribution of PFASs in WtE residues. Sampling was performed during incineration of two different waste mixes: normal municipal solid waste incineration (MSWI) and incineration of a waste mix with 5–8 wt % sewage sludge added to the MSWI (referred to as Sludge:MSWI). PFASs were identified in all examined residues, with short-chain (C4–C7) perfluorocarboxylic acids being the most abundant. Total levels of extractable PFASs were higher during Sludge:MSWI than during MSWI, with the total annual release estimated to be 47 and 13 g, respectively. Furthermore, PFASs were detected in flue gas for the first time (4.0–5.6 ng m–3). Our results demonstrate that some PFASs are not fully degraded by the high temperatures during WtE conversion and can be emitted from the plant via ash, gypsum, treated process water, and flue gas.

Fate of perfluoroalkyl and polyfluoroalkyl substances (PFAS) through two full‐scale wastewater sludge incinerators

“…The FBF followed similar trends, but the measurements of the shorter chain PFCA compounds in the stack were not useable due to contamination. Björklund et al (2023) found PFBA to be the most abundant PFAS detected in stack samples from a municipal solid waste (MSW) incinerator while processing MSW alone or when co‐processing dewatered wastewater sludge. Unfortunately, PFBA and PFPeA analyses can be compromised by interferences (Bangma et al, 2023), so results reported here must be viewed with some skepticism until the previously noted nontargeted analyses are completed.…”

Levels of per- and polyfluoroalkyl substances (PFAS) in various wastewater-derived fertilizers – analytical investigations from different perspectives

“…The lowest PFAS values were detected for the pyrolyzed products which is also in good agreement with previous studies. 55,56 However, it has to be kept in mind that thermal treatment of PFAS containing fertilizers may produce volatile ultrashortchain PFAS 57,58 or organouoride compounds like CF 4 , CHF 3 etc. 59 which have a high global warming potential, and may aerwards enter the atmosphere, depending on the used lter systems in thermal treatment plants.…”

Distribution of Per- and Polyfluoroalkyl Substances (PFASs) in a Waste-to-Energy Plant─Tracking PFASs in Internal Residual Streams

“…Condensate, boiler ash, and filter ash were collected and pooled on three occasions per sampling day (Table S2). Flue gas was sampled before the wet flue gas cleaning (Figure ) using the EN 1948:1 cooled probe sampling train (Figure S1), which was modified with additional features from air-sampling methodologies described elsewhere . Sludge from the internal water treatment was not accessible at the time of sample collection.…”

“…Sample preparation has been described in detail elsewhere. , Briefly, boiler ash and filter ash were weighed into a polypropylene tube and spiked with 3 ng internal standard. To each tube, 5 mL of methanol was added before vortexing for 10 s. Thereafter, samples were ultrasonicated for 15 min before being centrifuged for 10 min at 1200 g .…”