Evaluation of Soil Washing as Remediation for PFAS-Contaminated Soil

Sammanfattning

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants. Due to their chemical structure, these compounds pose risks to ecosystems and human health, creating a need for effective remediation strategies. This study evaluates the applicability of soil washing as a remediation technique for PFAS-contaminated soils, with a focus on identifying conditions under which the method is effective and most suitable. A literature study was conducted, compiling data from recent field- and pilot-scale studies of soil washing at sites contaminated by firefighting foam. The results show that the removal efficiency varies widely between studies, with removal of perfluoroctane sulfonic acid (PFOS) ranging from 11% to over 99%, depending on multiple factors. Soil characteristics, particularly grain size distribution, strongly influence the performance, with higher efficiencies in coarse-grained soils. In addition, the composition of the washing solution, type of PFAS, and choice of treatment approach were also found to affect removal outcomes, while cost and operational constraints influence practical applicability. Comparison between studies was limited by differences in methodology, reporting, and analytical focus, highlighting a lack of standardization and available field data. The study concludes that soil washing can be an effective remediation method under favorable conditions, particularly when applied ex-situ in coarse-grained soils, but that its applicability is site specific and may require combination with complementary techniques.