SUMMARY

• This study evaluated the feasibility of using sorbents to immobilise Per- and Polyfluoroalkyl Substances (PFAS) in soils at an international airport located in Australia.
• The PFAS sorptive capacity of 8 different sorbents was measured using the Standardised Sorbent Qualities Measure (SSQM) and Matrix Sorbent Qualities Measure (MSQM) tests.
• RemBind 100 and PS1300 achieved the best results for PFOS+PFHxS sorption compared to the other sorbents tested. RemBind 100 was selected for further bench-scale testing and field-scale deployment based on a cost-benefit analysis.
• Bench-scale trials involved mixing RemBind 100 with PFAS-contaminated soils from the airport site at different dosage rates and measuring PFAS leachability using the Australian Standard Leaching Protocol (ASLP) at pH 5 and 7.
• Bench-scale results showed that RemBind 100 at 1 – 2% dosage rate reduced PFOS+PFHxS leachability by 99%, meeting the current drinking water criteria in Australia (0.07ug/L).
• In the field, RemBind 100 was applied to 8,000 tonnes of soil at 1 – 2% using three different mixing approaches; an excavator, a trommel screen, and a pugmill.
• ASLP analyses of treated soil samples showed similar PFAS leachability reductions as the bench-scale tests, with all tested samples meeting the onsite target criteria of 0.4 ug/L for PFOS+PFHxS.
• The Sorbent Assisted Uniformity Test (SAUT), an infield dye-based kit, was used to determine the uniformity of sorbent addition across the treated soil stockpiles.
• The SAUT results demonstrated relatively consistent blending results across all three mixing techniques.