SPIRIT – Strategies for PFAS in-situ remediation using innovative technologies

Per‑ and polyfluoroalkyl substances (PFAS) are considered one of the greatest challenges for soil and groundwater protection because of their high persistence, toxicity, and complex environmental chemistry. A particularly prominent example is the extensive PFAS contamination in the Rhine Valley between Rastatt and Baden‑Baden.

The aim of this project is to systematically investigate and further develop different in‑situ remediation technologies for PFAS‑contaminated soils, enabling their future application on polluted sites. Three sub‑projects address various technological approaches.

In this work package, thermal desorption and transformation are examined as an in‑situ remediation method for PFAS‑contaminated soils under varying boundary conditions (e.g., additives, temperatures, heating duration). The focus is on identifying PFAS conversion processes and applying mass‑balance approaches during the thermal treatment.
The planned investigations build on the results of the BMBF project PFClean and aim to gain further experience for potential field application. This includes deriving key design parameters such as required heating times, target temperatures, and the sizing of heating elements and soil‑air extraction systems.

The aim of this work package is to deliberately promote and accelerate the conversion of PFAS precursor compounds into more mobile end products, often short‑chain PFAS at the terminus of the transformation chain. Laboratory experiments will be used to gain a deeper understanding of the underlying mobilization and transformation processes and to optimize them for potential field application. The focus is on identifying parameters that create favorable conditions for biological availability and conversion, such as temperature, chemical additives, or surfactants.

In this work package a technical approach is investigated to capture PFAS‑containing water in the transition zone between the unsaturated and saturated soil layers. The goal is to collect PFAS masses that can accumulate at air‑water interfaces above the capillary zone. The central hypothesis is that temporary changes in water level—e.g., due to natural groundwater fluctuations—mobilize PFAS from the unsaturated zone, allowing them to be removed via suitable collection elements.

Claus Haslauer

Anna Burkhardt

Erin Huggett

VEGAS

01.10.2025 until 31.07.2027

Ministry for the Environment, Climate and Energy Sector
Regierungspräsidium Karlsruhe

DVGW - Technologiezentrum Wasser (TZW), Karlsruhe