Abstract

Abstract Sustainable reuse of biosolids as fertilizers is being threatened by the presence of per‐ and polyfluoroalkyl substances (PFAS) in our waste stream warranting research on strategies that will minimize PFAS mobility from land‐applied biosolids. Here, we evaluated the ability of waste‐derived sorbents aluminum chlorohydrate water treatment residuals (ACH‐WTRs, 1 wt%) and biosolids‐based biochar (1.5 wt%) to reduce mobility of PFAS in columns with 3 wt% biosolids‐amended soils with and without sorbent layered on top of soil only and operated under transient unsaturated conditions. Cycles of simulated rain events of approximately three pore volumes distributed over a 4‐day period followed by 3 days of drying were imposed for 6 months. Total PFAS concentrations in collected leachates were lower in the sorbent‐treated columns compared to the control columns. Biochar outperformed the ACH‐WTR with 41% versus 32% lower total PFAS in leachate, respectively, compared to the control. The most significant mitigation effect was observed with PFOS (perfluorooctane sulfonate) with 68% and 62% less PFOS in the leachates from the columns treated with ACH‐WTR or biochar compared to the control, respectively. These results provide a first‐of‐its‐kind assessment of the potential benefit of co‐applying WTRs or biochar with biosolids to reduce PFAS mobility in biosolids‐amended soils.