Partitioning, mobility and persistence of PFAS in biosolids-based compost products across solid and aqueous matrices

Area of Science:

• Environmental Chemistry
• Environmental Science
• Soil Science

Background:

• Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants.
• Biosolids composting is a common waste management practice.
• Understanding PFAS behavior in compost is crucial for environmental risk assessment.

Purpose of the Study:

• To evaluate the persistence, release, and mobility of PFAS from composted biosolids and vegetative waste.
• To characterize PFAS partitioning between solid and aqueous phases in composted materials.
• To assess the implications of composting on PFAS environmental transport.

Main Methods:

• Laboratory experiments simulating post-application conditions (pH 7.5).
• Analysis of 40 PFAS in various compost matrices and leachates using a modified U.S. EPA Method 1633.
• Evaluation of PFAS partitioning for 15 predominant PFAS in solid samples and leachate.

Main Results:

• Strong matrix-dependent PFAS behavior observed.
• Long-chain PFAS showed greater retention in solids; short-chain PFAS mobilized to water.
• Sulfonates had higher affinity for vegetative matter than carboxylates; screen overs enriched in precursors.

Conclusions:

• Composting modifies PFAS partitioning by altering organic matter composition.
• Dual-release behavior: rapid release of short-chain PFAS, slower release of long-chain PFAS and precursors.
• Findings have significant implications for groundwater transport and risk assessment of land-applied composts.