In‐situ application of colloidal activated carbon for PFAS‐contaminated soil and groundwater: A Swedish case study

Abstract

Soil and groundwater contamination by per-and polyfluoroalkyl substances (PFAS) has been a significant concern to human health and environmental quality. Remediation of contaminated sites is crucial to prevent plume expansion but can prove challenging due to the persistent nature of PFAS combined with their high aqueous mobility. In this case study, we investigated the potential of colloidal activated carbon (CAC) for soil stabilization at the pilot scale, aiming to entrap PFAS and prevent their leaching from soil into groundwater. Monitoring of the site revealed the presence of two potential sources of PFAS contamination at concentrations up to 23 μg L −1 for ∑ 11 PFAS in groundwater. After CAC application, initial results indicated a 76% reduction of ∑ 11 PFAS and high removal rates for long-chain PFAS, such as perfluorooctane sulfonic acid and perfluorooctanoic acid. A spike in concentrations was noticed 6 months after injection of CAC, showing a rebound of the plume and a reduction of treatment effectiveness. Based on long-term monitoring data, the treatment effectiveness for ∑ 11 PFAS dropped to 52%.The rebound of concentrations was attributed to the plume bypass of the barrier due to the presence of high conductivity zones, which likely occurred because of seasonal changes in groundwater flow directions or the CAC application at the site. This demonstrates the need for a detailed and accurate hydrogeological understanding of contaminated sites before designing and applying stabilization techniques, especially at sites with high geologic and hydrologic complexity. The results herein can serve as a guideline for treating similar sites and help avoid potential pitfalls of remedial efforts.

Distribution of Per- and Polyfluoroalkyl Substances (PFASs) in a Waste-to-Energy Plant─Tracking PFASs in Internal Residual Streams

“…Notably, activated carbon is injected before the fabric filters to capture other incineration-related contaminants. Since activated carbon is used in the remediation of PFAS-contaminated water and soil (see e.g., , ), it was reasonable to expect that the addition of activated carbon would affect the PFAS content of filter ash. There was also the possibility that the fabric filters, which according to the supplier contain Teflon, could be a contributing factor to the PFASs found in the filter ash.…”

Comprehensive Review of Global Perspectives on Per- and Polyfluoroalkyl Compounds: Occurrence, Fate, and Remediation in Groundwater Systems

“…Integrating technologies, such as using ion exchange resins with electrochemical oxidation or applying UV radiation in combination with electrochemistry, enables a more efficient approach to treating PFASs [15,77,78]. Novel in situ remediation techniques, such as colloidal activated carbon injection and electrochemical oxidation, eliminate the need for groundwater extraction [20,79]. Pilot and field studies have successfully optimized using granular activated carbon and anion exchange technologies to remove PFASs, as reported by some studies [7,72].…”

Challenges and Remediation Strategies for Per- and Polyfluoroalkyl Substances (PFAS) Contamination in Composting

“…Most studies have focused on the treatment of PFAS-contaminated soil remain in the experimental phase, while others have been tested in the field. Among these techniques is stabilisation [127][128][129].…”