In-Situ Treatment of PFAS Using D-FAS Technology

Dr. David Reynolds | Geosyntec Consultants

ER19-5075

Objective

The over-arching objective of this project is to demonstrate that the D-FAS technology is a cost-effective, easily implemented, sophisticated solution requiring minimal infrastructure that efficiently removes per- and polyfluoroalkyl substance (PFAS) source zone mass, thus reducing discharge to groundwater systems, and lowering concentrations at downgradient receptors. Given the extensive laboratory testing previously conducted on this technology, the focus of the project will be an in situ pilot test demonstration/validation, enhanced by a limited site-specific bench test, designed to identify and optimize multiple important parameters that will allow the technology to be scaled to full-scale applications.

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Technology Description

The D-FAS technology has been developed through extensive laboratory and preliminary field testing. It is an in situ process that exploits the preference for PFAS to accumulate at air/water interfaces such as gas bubbles. In the D-FAS approach, gas bubbles are added to the base of a treatment well, and as the bubbles rise through the water column, PFAS spontaneously transfer from the dissolved phase to bubble surfaces due to their inherent partitioning properties. PFAS-laden bubbles accumulate at the top of the water column as a foam (inside the treatment well), which is then removed by a device under vacuum. The foam is condensed into a low volume, liquid concentrate which can subsequently be treated by high temperature incineration or similar methods either on- or off-site.

D-FAS can remediate groundwater and soil concentrations to very low, potentially regulatory guideline levels. It can remove high PFAS mass in source areas and lower groundwater concentrations in downgradient areas in significantly shorter timeframes and with significant cost savings compared to conventional pump and treat approaches. This project is focused on demonstrating the effectiveness of the technology with source zone concentrations in the field and collecting engineering data to support future field applications.

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Benefits

D-FAS is an innovative in situ technology that can significantly reduce the DoD's PFAS liability cost-effectively. Application of the technology in PFAS source zones will result in significant mass removal resulting in reduced source zone mass discharges to plumes and downgradient receptors and has the potential to achieve current groundwater concentration guidelines.

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Points of Contact

Principal Investigator

Dr. David Reynolds

Geosyntec Consultants

Phone: 519-515-0883

Program Manager

Environmental Restoration

SERDP and ESTCP

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