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Communication Dans Un Congrès Année : 2023

Towards a robust reactive transport model to simulate fate and transport of PFAS from surface to groundwater

Samuel Mertz
  • Fonction : Auteur
  • PersonId : 1041982
Anne Togola
Julie Lions

Résumé

The H2020 PROMISCES project (GA-101036449) aims to promote a zero-pollution circular economy by overcoming the presence of contaminants, notably poly- and perfluoroalkyl substances (PFAS), in the soil-sediment-water system. Hence, a sound understanding of their retention and transport behavior in the soil-aquifer continuum is mandatory. Reactive transport models are suitable tools to tackle this goal albeit their robustness is still questioned, mainly due to their use on a narrow range of experimental dataset. The aim of this study is to test their efficiency to predict PFAS mobility over a broad range of environmental conditions by simulating a large set of column experiments. A 1D reactive transport model has been based on a coupling between HYDRUS-PHREEQC software. Richards equation was used to simulate variably saturated water flow. Reactive transport were simulated by accounting for advection-dispersion, rate-limited diffusive transfer between mobile-immobile domains and thermodynamic equilibrium and/or kinetically-constraints adsorption processes at solid-water interface (SWI) and air-water interface (AWI). Model calibration and validation have been based on column experiments in saturated and unsaturated conditions carried out on a sand material and a soil. A mix of 4 PFAS (PFOA, PFOS, PFHxS and PFBS) were used. For each PFAS, concentration in the inlet solution was either 5 mg L-1 or 5 µg L-1, hence mimicking contaminated site or environmental conditions. The whole set of PFAS breakthrough curves were accurately simulated. Simulations results illustrated that the amounts of PFAS sorbed at SWI and AWI remained low in regards to the amount in aqueous phases at high PFAS concentration. Hence, transport processes controlling PFAS mobility. At low PFAS concentration, sorption processes at SWI in saturated conditions and at SWI and AWI in unsaturated conditions play a key role. We also highlight that calibration of some model parameters associated with sorption processes at AWI and rate-limited diffusive transfer was concentration-dependent. Lower PFAS concentration is, higher values of model parameters are. This trend is greater for the compounds with longer carbon chain. In order to overcome this limit preventing to simulate PFAS mobility from contaminated site to less affected environmental compartments, ongoing conceptual and numerical developments are done.
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Dates et versions

hal-04151957 , version 1 (05-07-2023)

Identifiants

  • HAL Id : hal-04151957 , version 1

Citer

Nicolas Devau, Samuel Mertz, Hugues Thouin, Mohamed Djemil, Stéfan Colombano, et al.. Towards a robust reactive transport model to simulate fate and transport of PFAS from surface to groundwater. Goldschmidt 2023 - International conference on geochemistry and related subjects, European Association of Geochemistry; Geochemical Society, Jul 2023, Lyon, France. ⟨hal-04151957⟩

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