Formation and partitioning behaviour of perfluoroalkyl acids (PFAAs) in waste activated sludge during anaerobic digestion

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

20 Scopus Citations
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Author(s)

  • Yijing Li
  • Jennifer Bräunig
  • Guerrero C. Angelica
  • Phong K. Thai
  • Jochen F. Mueller

Detail(s)

Original languageEnglish
Article number116583
Journal / PublicationWater Research
Volume189
Online published30 Oct 2020
Publication statusPublished - 1 Feb 2021
Externally publishedYes

Abstract

The formation and fate of perfluoroalkyl acids (PFAAs) in sludge during anaerobic digestion (AD) is of global importance since the sludge is a significant source of PFAAs to the environment. The formation of PFAAs from polyfluorinated compounds, namely PFAA precursors, is poorly understood in AD. This study aims to investigate the formation of PFAAs from precursors and their partitioning behaviour in waste activated sludge (WAS) during AD process. To achieve this, three isotope-labelled PFAAs were spiked and monitored along with indigenous PFAAs and precursors over eight weeks in a laboratory-scale anaerobic digester, fed with sludge from a local wastewater treatment plant and operated with a hydraulic retention time of 12 days under 35 ℃. In addition to isotope-labelled PFAAs, twelve native PFAAs and eight polyfluorinated compounds were detected in the feed and digested sludges. A mass-balance model, validated by the spiking experiment, was applied to predict the concentrations of PFAAs and precursors assuming no formation/degradation in AD. The measured concentrations of short-chain PFAAs (perfluoroalkyl carboxylates (PFCAs): C < 8; perfluoroalkane sulfonates (PFSAs): C < 6) in the AD sludge were significantly (p < 0.05) higher than the model-predicted concentrations, indicating the formation of these PFAAs from precursors in AD. In contrast, the formation of long-chain PFAAs (PFCAs: C ≥ 8; PFSAs: C ≥ 6) was not observed. Moreover, the degradation of two polyfluoroalkyl phosphates (PAPs) (6:2 PAP and 6:2/8:2 diPAP) occurred, evidenced by their measured concentrations that were statistically lower than the mass-balance predictions. Further, the AD process reduced the amount of PFAAs absorbed/adsorbed to sludge, particularly for the long-chain ones, due to the breakdown of solids. © 2020 Elsevier Ltd.

Research Area(s)

  • Adsorption, Anaerobic sludge digestion, Distribution coefficient, Mass balance, Perfluoroalkyl acids, Precursors

Citation Format(s)

Formation and partitioning behaviour of perfluoroalkyl acids (PFAAs) in waste activated sludge during anaerobic digestion. / Li, Yijing; Bräunig, Jennifer; Angelica, Guerrero C. et al.
In: Water Research, Vol. 189, 116583, 01.02.2021.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review