Perfluoroalkyl and Polyfluoroalkyl Substances Release from Biosolid-Derived Compost

Area of Science:

• Environmental Chemistry
• Soil Science
• Contaminant Hydrology

Background:

• Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants found in biosolid-derived compost.
• Understanding PFAS release mechanisms from compost is crucial for assessing environmental risks and developing management strategies.

Purpose of the Study:

• To investigate the release potential and controlling mechanisms of various PFAS from compost.
• To evaluate the influence of eluent chemistry (water, NaCl, CaCl2) and compost properties on PFAS desorption.

Main Methods:

• Sequential leaching experiments using water and saline solutions (10 mM NaCl, 5 mM CaCl2) on biosolid-derived compost.
• Analysis of PFAS, dissolved organic matter (DOM), and major ions in eluate.
• Modeling PFAS desorption kinetics using a first-order two-compartment model.

Main Results:

• PFAS desorption followed a biphasic pattern (rapid then slow release), well-described by a two-compartment model.
• Electrostatic interactions, particularly Ca2+ bridging, significantly influenced PFAS release, with shorter-chain PFAS desorbing faster.
• Dissolved organic matter (DOM) complexation enhanced PFAS release under specific ionic conditions, indicating coupled release mechanisms.

Conclusions:

• PFAS mobility from compost is governed by a complex interplay of compost matrix properties, PFAS molecular structure, and eluent chemistry.
• Electrostatic interactions and DOM complexation are key mechanisms controlling PFAS release, necessitating tailored management approaches.