BRGM: PFAS contaminated site - Fate, transport and remediation of soil and groundwater contaminated by AFFFs

Case Study 6 aims to assess the  fate and migration of PFAS from contaminated soil by aqueous film forming foams (AFFF) to groundwater. It also aims to develop innovative, sustainable, and cost-effective technologies for the PFAS treatment of contaminated soil and groundwater.

To achieve this ambitious objective, BRGM has conducted experimental works at laboratory scale. Furthermore, BRGM will apply AFFFs on topsoil under controlled conditions in its experimental platform “PRIME”, located in Orléans (France). PRIME serves as a research infrastructure bridging the gap between laboratory experimentation and large-scale field trials.

The laboratory experiments, conducted to assess the fate and transport of PFAS in a porous media, allow also to design the pilot-scale test. The first set of experiments demonstrated the key role of sorption at interface to control the fate and transport of PFAS in porous media.

The pluri-metric pilot (PMP) was filled by man-made soil and equipped with monitoring devices including sampling devices and sensors. In a second step, hydrogeological tests were conducted to control the hydrodynamics properties of the man-made soil characterized at laboratory scale.

The application of AFFF with former formulae containing PFAS will be done onto topsoil of the plurimetric pilot scale experiment PRIME, in April 2024. Methods developed by BRGM in WP1 (Development and implementation of analytical and toxicological methods and derived monitoring strategies) will be used for monitoring the AFFF plume, such as analyses of Total Fluor, Adsorbable Organic Fluorine and target analysis of specific PFAS identified in the selected AFFF.

 

In parallel, remediation tests to remove PFAS are conducted. The PFAS degradation experiments with Zero Valent Iron made it possible to destroy certain PFAS and also to adsorb part of it (i.e. extraction of the aqueous phase). In addition, dimethylsulfoxide also helped destroy certain PFAS.

Soil flushing using Non-Newtonian fluids (NNF) (gels with solvent) have demonstrated the effectiveness of the process even in heterogeneous environments. At lab-scale, BRGM has demonstrated that it is possible to extract PFAS from soils with high efficiency (remediation yields are greater than 90%).

Initial experiments utilizing sonocavitation to degrade PFAS have shown great promise. Further investigations involving varying frequencies and power levels will be conducted on AFFF.

The first experiments with biological treatment based on bacteria highlighted a degradation of certain PFAS.

All these processes developed in the laboratory will be implemented on a pilot-scale in the PMP PRIME. 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).