CS #7: Remediation of groundwater affected by PFAS and organochlorines, Northeastern Spain
Our aim: restoring polluted groundwater
Case Study 7 considers two aquifers in northeastern Spain: one contaminated with polyfluoroalkyl substances (PFAS) and the other contaminated with chlorinated solvents. Different oxidation/reduction processes (e.g. persulfate, ferrate, nano-zero valent iron) are being tested at the laboratory scale to find the best solution for degrading these pollutants.
The most effective best reagent combination for removing PFAS will be scaled up to the field scale to remediate the polluted groundwater in-situ. Additionally, a simple box model capable of predicting the fate and transport of PFAS in groundwater is being developed.
Find here the abstract "Dealing with a PFAS-polluted aquifer: from modelling to in-situ remediation treatment" from the EGU 2022 conference.
Sampling groundwater on the field for PFAS determination. @Hèctor de Buen (Esolve)
Preparation and analysis of chlorinated organic compounds by HS-SPME-GC (head-space (HS)- solid phase microextraction (SPME)-gas chromatography (GC). @Alicia Cano (IDAEA-CSIC)
What we have done so far...
So far, the initial state of the site has been characterized. In order to build the fate and transport model, saturated column experiments have been conducted to study the behaviour of pollutants in groundwater and in contact with soil (PFAS adsorption). We have begun incorporating all available parameters to model PFAS adsorption in the unsaturated zone. In the coming months, we will model the saturated zone.
We have completed laboratory-scale experiments (batch experiments with real groundwater and soil, and column experiments) testing innovative technologies to remove PFAS and organochlorine pollutants. We have found that the best reagents combination for removing organochlorine pollutants is PS+nZVI, achieving between 70 and 99 percent removal in batch experiments with contaminated groundwater.
Regarding PFAS compounds, we have determined that the best reagent combination for PFAS removal is Persulfate + Ferrate (VI), achieving removal rates between 67 and 95 percent in column experiments using spiked groundwater and soil from the case study. Additionally, a tracer test has been conducted in the field. In early July, we will scale up the treatment to implement it at field scale (only for the aquifer contaminated with PFAS).
For more information check out our recent scientific publication “Novel Oxidation Strategies for the In Situ Remediation of Chlorinated Solvents from Groundwater—A Bench-Scale Study”.
