PFAS Uptake by Plants in Soils Amended with Biosolids Derived from Wastewater with Industrial Input

Per- and polyfluoroalkyl substances (PFAS) present in biosolids pose challenges for the management of biosolids land application. This study evaluated the phytoremediation potential of a grass-legume mixture derived from a Conservation Reserve Program (CRP) seed blend for removing PFAS from biosolids-amended soils treated with biochar. Thirteen representative PFAS were monitored in plant tissues over a 92 day greenhouse experiment. Results showed that PFAS uptake was significantly influenced by soil type, biochar type and dose, and biosolids characteristics. Notably, biosolids derived from a mixture of industrial and domestic wastewater, containing higher concentrations of PFAS precursors (1515.9 ± 1.89 μg/kg), resulted in reduced plant biomass and lower ΣPFAS removal of 0.3–0.7% compared to 1.0–2.5% of ΣPFAS removal with biosolids comprising PFAS precursors of 6.30 ± 1.89 μg/kg sourced solely from domestic wastewater. While low-dose biochar (0.05%) enhanced PFAS uptake under certain conditions, higher doses (5%) generally stabilized PFAS, reducing their bioavailability. Isotopically labeled PFHxS and PFNA confirmed these patterns, with chain length influencing uptake efficiency. Leaching tests using water revealed that biochar amendments reduced PFAS leachability in Scantic soil but increased it in Woodbridge soil, highlighting the need for site-specific remediation strategies. Overall, PFAS phytoextraction was less effective in biosolids derived from mixed industrial and domestic sources compared with those from domestic wastewater alone. This study highlights the importance of tailoring phytoremediation and biochar applications to biosolids composition and soil properties to ensure safe and effective PFAS management.