Modelling subsurface PFAS transport with focus on in-situ stabilization with sorbents

Description

The migration of PFAS both in the unsaturated (vadose) zone and the groundwater zone is complex and is affected by several processes that are partly different compared to traditional, more well-studied pollutants. At the same time, modeling tools for PFAS transport are relatively untested and in need of development with respect to several PFAS-specific processes such as; retention on air-water surfaces in the unsaturated zone, transformation of precursors and competitive effects between different PFAS both when sorbing to air-water interfaces and to solid material. Within their governmental assignment on PFAS mitigation (RU PFAS), the Swedish Geological Survey (SGU) and the Swedish Geotechnical Institute (SGI) generate large amounts of data from pilot trials with injection and mixing of activated carbon sorbents for in-situ stabilization of PFAS. Modeling the transport and retention processes is an important part of being able to interpret the results of the pilot trials and learn from them. This research project will evaluate and develop modeling tools to better understand the effects of in-situ stabilization on fate and transport of PFAS in soil-groundwater systems. The modeling is done in collaboration with researchers at SGI. The purpose is partly to develop modeling tools that can facilitate evaluation and design of in-situ stabilization measures for PFAS and partly to contribute to the evaluation of SGI's and SGU's pilot trials with in-situ stabilization within the governmental assignment RU PFAS. The project is expected to contribute to better models to predict how PFAS spreads from contaminated hotspots and what the effect of in-situ stabilization will be. Comparisons of different models, methods of applying them and verification against detailed field data should further provide information on the suitability and robustness of the models.