PFAS fate using lysimeters during degraded soil reclamation using biosolids

Area of Science:

• Environmental Science
• Soil Science
• Environmental Chemistry

Background:

• Biosolids are valuable soil amendments but contain per- and polyfluoroalkyl substances (PFAS).
• Concerns exist regarding PFAS leaching into groundwater and plant uptake from biosolids application.
• Degraded soils require effective remediation and nutrient enrichment strategies.

Purpose of the Study:

• To investigate the persistence and leaching of PFAS from biosolids applied to a simulated degraded soil environment.
• To evaluate the impact of blending biosolids with mulch on PFAS leaching.
• To compare PFAS leaching under different application rates and fertilizer treatments.

Main Methods:

• Application of biosolids and biosolids-mulch blends at varying rates to lysimeters mimicking degraded soils.
• Collection and analysis of leachate over a 2-year period.
• Quantification of PFAS using isotope-dilution, solid-phase extraction, and LC-MS/MS.

Main Results:

• Leachate PFAS concentrations initially high, then declined, with quantifiable levels proportional to biosolids application rates.
• Short-chain perfluoroalkyl acids dominated leachate, while longer chains were more prevalent in soil.
• A 43% biosolids-mulch blend reduced PFAS leachate concentrations by 21% compared to biosolids alone, despite higher application rates.

Conclusions:

• Biosolids blending with mulch is a viable strategy to reduce PFAS leaching.
• Mulch blending enhances PFAS retention in soil, particularly for long-chain compounds.
• This approach supports the sustainable beneficial reuse of biosolids in agriculture and land reclamation.