SUMMARY

• The objective of this study was to evaluate four sorbents (RemBind, Biochar Basic, Earthlite, Calgon F400) for the removal of both heavy metals and Per- and Polyfluoroalkyl Substances (PFAS) from stormwater.
• Initial screening studies were performed using synthetic water dosed with heavy metals (copper and zinc) and PFAS (PFOS, PFOA, PFHxS).
• Biochar Basic and Earthlite resulted in greater removals of copper and zinc (75 – 99%) than RemBind (60 – 85%). Calgon F400 showed the poorest removal of heavy metals with 69% for copper and little or no removal for zinc.
• For PFAS, RemBind showed the best removal efficiencies of 84 – 95% compared to 28 – 81% for Calgon F400. Biochar Basic showed particularly poor PFAS removal efficiencies (<10% for PFOS, PFOA and PFHxS) compared to 28 – 55% for Earthlite.
• Real stormwater collected from a field site was characterised in order to determine which matrix components impact sorbent performance.
• Organic matter in the real stormwater significantly decreased the PFAS removal efficiencies of RemBind from 84 – 95% to 0 – 45%. Pretreating the real stormwater with Biochar Basic removed suspended solids and subsequently resulted in significantly greater PFAS removals by RemBind (20 – 60% increase) for 11 out of 21 PFAS species.
• The final sorbents selected for the real stormwater treatment were Biochar Basic, which is first deployed for heavy metal and solids removal, followed by RemBind for PFAS removal.