The decomposition and emission factors of a wide range of PFAS in diverse, contaminated organic waste fractions undergoing dry pyrolysis

• Published in: Journal of hazardous materials Vol. 454; p. 131447
• Main Authors: Sørmo, Erlend, Castro, Gabriela, Hubert, Michel, Licul-Kucera, Viktória, Quintanilla, Marjorie, Asimakopoulos, Alexandros G., Cornelissen, Gerard, Arp, Hans Peter H.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.07.2023
• Subjects: Biochar; Emission factors; Mass balance; Method development; Organic waste; PFAS; Pyrolysis; Sewage sludge; Emission factors; Mass balance; Pyrolysis; Organic waste; Method development; Biochar; Sewage sludge; PFAS
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2023.131447

Current treatment options for organic waste contaminated with per- and polyfluoroalkyl substances (PFAS) are generally limited to incineration, composting or landfilling, all resulting in emissions. Dry pyrolysis is a promising emerging alternative to these practices, but there is uncertainty related to the fate of PFAS during this process. The present work first developed a robust method for the determination of PFAS in complex matrices, such as sewage sludge and biochar. Then, a mass balance was established for 56 different PFAS during full-scale pyrolysis (2–10 kg biochar hr-1, 500–800 °C) of sewage sludges, food waste reject, garden waste and waste timber. PFAS were found in all wastes (56–3651 ng g-1), but pyrolysis resulted in a ≥ 96.9% removal. Residual PFAS (0.1–3.4 ng g-1) were detected in biochars obtained at temperatures up to 750 °C and were dominated by long chain PFAS. Emitted PFAS loads ranged from 0.01 to 3.1 mg tonne-1 of biochar produced and were dominated by short chain PFAS. Emissions made up < 3% of total PFAS-mass in the wastes. Remaining uncertainties are mainly related to the presence of thermal degradation products in flue gas and condensation oils. [Display omitted] •A robust protocol for determination of PFAS in complex matrices such as sewage sludge and biochar.•Multiple PFAS congeners present at elevated concentrations in eight different organic waste fractions.•Residual PFAS concentrations in biochars produced between 500 and 800ºC.•> 95% of PFAS decomposed or accumulated in pyrolysis oil following dry pyrolysis > 500ºC.•Emission factors of PFAS during pyrolysis dominated by short chains and range 0.01 – 3.1 mg tonne-1.