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.