Objective
The goal of this project is to develop a prototype mobile system capable of destructive treatment of per- and polyfluoroalkyl substances (PFAS) in soils and sediments, targeting concentrations ranging from parts per billion to parts per million levels and capable of being transported and implemented at various sites. The goal of the technology is to enable the unrestricted disposal, discharge, and/or reuse of PFAS-impacted soils and sediments. Specific objectives include:
- Conduct laboratory-scale treatability testing under field-like conditions to optimize a treatment train involving mechanochemical ball milling, soil washing, and plasma treatment.
- Design a field-scale treatment train using three technologies: ball milling, soil washing, and plasma treatment, and construct a mobile ball mill system.
- Conduct a field demonstration of the treatment train using the mobile ball mill system, soil washing equipment, and plasma treatment to treat impacted soil.
Technology Description
This project will use an integrated treatment train to advance technology readiness rapidly within the two-year project duration, which includes ball milling treatment, soil washing, and plasma treatment. It is hypothesized that ball milling treatment can destroy most of the PFAS in sediment. The remaining short-chain fluorocarbons (if any) are more hydrophilic and, therefore, can be washed off together with the residual co-milling reagents. The plasma process can then treat the rinse solution, and the post-treatment sediments can be returned to the environment, avoiding expensive management of the media.
The system will first be tested on a field-like scale, using five gallons of sediment, followed by a field-scale demonstration to treat multiple 55-gallon drums of sediments. Throughout testing, forty PFAS will be measured in ambient samples, wash solution, rinse solution, solids extract, and plasma-treated aqueous phase following the U.S. Environmental Protection Agency Draft Method 1633.
Technology Schematic Diagram
Benefits
The results from this project will contribute to both fundamental science and practical engineering. The laboratory-scale validation is anticipated to yield the following:
- An in-depth understanding of the interplay between co-milling reagents and PFAS in sediment
- Best practices to enhance soil washing efficiency
- Optimized conditions for plasma treatment of spent soil washing solutions
The project will also mark the first cross-media PFAS treatment paradigm through the integration of the three most promising physical-chemical processes. If successful, the outcomes will prepare the team for future customization of this treatment train to suit site-specific conditions and provide a sustainable alternative for managing PFAS-impacted soils and sediments at their sites. (Anticipated Project Completion - 2025)