CS6: Fate and transport and (bio)remediation of soil and groundwater contaminated by PFAS from AFFFs, Orléans
@BRGM
Our aim: To assess PFAS fate and migration from soil to groundwater and technologies for their treatment
When PFAS-containing Aqueous Firefighting Foams (AFFF) are used, the surrounding soil and groundwater can be contaminated. Case Study 6 has therefore set itself the goal to assess PFAS fate and migration from soil to groundwater and to develop innovative, sustainable, and cost-effective technologies for the treatment of soil and groundwater polluted by PFAS.
To reach these goals, Case Study 6 is conducting an experimental application of AFFFs on topsoil under controlled conditions from lab-scale to semi-real conditions in an experimental platform in Orléans called "PMP PRIME" (PMP stands for pluri-metric pilot), a research infrastructure that connects laboratory experiments and full-scale tests.
In the PMP, Promisces Partner BRGM will perform a long-term experiment over six months. The monitoring will be carried out by using water sampling at several depths for analysis as well as specific probes and sensors. By reproducing the soil, vadose zone and groundwater matrices at semi-real scale, the PMP plant provides 4D monitoring of the unsaturated-saturated continuum. It is the ideal environment for scaling up TRL and validating and demonstrating remediation technologies.
What we have done so far...
We already reached two milestones: First, laboratory experiments were carried out in an unsaturated column to assess the fate and transport of PFAS in a porous media to design the pilot-scale test. The set of experiments demonstrated the key role of sorption at the interface to control PFAS fate and transport in porous media. Second, models of transport of PFAS in the vadose and saturated zone were performed using lab-scale experimental data and literature data.
At the same time, we are designing remediation tests to remove PFAS, based on laboratory experiments, from the porous media with non-Newtonians fluids (NNF) (foam and gels) and to treat the soil thanks to specific additives (reducers and other additives). It was shown that the in-situ chemical reduction was not the best solution. So the destruction of the PFAS will be carried out on site.
@BRGM
The injection of NNF is a very promising technology in the field of in-situ treatment of soils and groundwater. Improving the know-how on this technology in the framework of PROMISCES will allow its application to many other polluted sites (alluvial medium, fractured medium). The results of the on-site PFAS treatment are also very promising: on-site reduction, sono-cavitation and biological degradation have highlighted interesting results.
During the second step of this study, the PMP was filled by man-made soil and equipped with monitoring devices, pumps, including sampling devices and sensors. We have also conducted hydrogeological tests to control the hydrodynamics properties of the porous media characterised at laboratory scale. In addition, we have completed the application of AFFF with former formulae containing PFAS onto topsoil of the plurimetric pilot scale experiment "PRIME". Prior to PFAS injection, a baseline monitoring was done, followed by the injection of a diluted AFFF solution to study PFAS transport. The current step involves monitoring PFAS migration with weekly water infiltrations and analyses until October 2024.
In parallel, remediation treatments for in-situ mobilization of PFAS, in-situ destruction of PFAS and groundwater on-site treatment are being worked on.
