Engineered biochar from fruit processing side-streams for PFAS mitigation and soil health in biosolids-amended soils

Overview

This research program converts fibrous fruit-processing side streams—spent citrus peel and apple pomace—into engineered biochar designed to serve dual purposes: retaining per- and polyfluoroalkyl substances (PFAS) in biosolids-amended agricultural soils and improving soil health. The work responds to the need for practical PFAS mitigation tools in farmland where biosolids application has introduced PFAS contamination, while simultaneously addressing soil quality goals.

The resulting biochar positions as a higher-value engineered remediation amendment relative to commodity biochar or activated-carbon benchmarks, combining PFAS retention with soil-health benefits such as improved water-holding capacity, nutrient value, and stable carbon content. The program leverages an established research platform—including feedstock characterization, oxygen-limited pyrolysis, PFAS analytical workflows, soil-column testing, and field trials—so new feedstocks can be validated efficiently and affordably.

Technical specifications

Representative citrus peel, apple pomace, blends, and fine residues are characterized to quantify feedstock variability, conditioning requirements, and quality-control targets. Conditioned materials are converted to biochar via oxygen-limited pyrolysis.

Candidate biochars are evaluated for:

• Yield, carbon content, pH, and nutrient content
• Specific surface area, porosity, and cation exchange capacity
• Water-holding capacity and stable-carbon indicators
• PFAS retention through batch screening and flow-through soil columns representing biosolids-amended agricultural soils
• PFAS leaching, breakthrough behavior, and soil-health metrics

The best-performing treatment advances to field-scale evaluation.

Technology readiness level

The research extends an active USDA NIFA-funded project (Award No. 2026-70001-46303) that has established and validated feedstock characterization, pyrolysis, PFAS analysis, soil-column testing, and field-trial workflows. This program adds fruit-processing side streams to that existing platform, with candidate biochars benchmarked against manure- and biosolids-derived biochars from the funded project. The current stage is laboratory- and column-scale validation (TRL 3–4), with the selected treatment progressing toward field-scale testing.