Ex Situ Remediation of Investigation-Derived Wastes containing PFAS by Electron Beam Technology
Suresh D. Pillai | Texas A&M University
This project will investigate the utility of high energy electron beam (eBeam) technology as an innovative approach for on-site treatment of investigation-derived waste (IDW) containing per- and polyfluoroalkyl substances (PFASs). The lead investigator has a published study demonstrating the capacity of eBeam technology to defluorinate perfluorooctanoic acid (PFOA) with levels of defluorination efficiency ranging from 35% to 100% depending on geochemical conditions. More recently, another study demonstrated that the degradation of PFOA and perfluorooctanesulfonic acid (PFOS) by eBeam irradiation followed pseudo-first-order kinetics. Defluorination rates were reported as 95.7% for PFOA and 85.9% for PFOS. The overall objectives of this research are:
- To quantify the effectiveness of eBeam technology at breaking down PFOS in soil and water under controlled experimental conditions, and;
- To characterize the effectiveness of eBeam at destructive treatment for a mixture of PFASs present in actual IDW samples collected from multiple sites.
The initial experimental approach will focus on eBeam mediated treatment of PFOS and PFOA by spiking PFAS-free sand and laboratory supplied PFAS-free water with PFOS and PFOA. The spiked media will be irradiated at varying eBeam doses (between 5 kilograys and 150 kilograys) followed by laboratory analysis. Upon optimization of the eBeam dose, additional testing will be conducted using field IDW samples obtained from representative Department of Defense (DoD) sites impacted by a range of aqueous film forming foam (AFFF)-derived PFASs. Samples will be analyzed before and after eBeam treatment for soil parameters (pH, alkalinity, % moisture content,) and cocontaminants to identify factors that may influence treatment efficiency of PFASs in IDW.
Preliminary data from Texas A&M University supports the efficacy of eBeam on pure solutions of PFASs. However, additional experimentation is needed to validate eBeam as a form of treatment for more complex mixtures such as IDW. Proof of concept validation and preliminary identification of factors influencing the efficacy of eBeam-based remediation will enable the near future development and scale-up of this alternative to high-temperature incineration for treatment of PFAS contaminated IDW. Because eBeam technology has the potential to be implemented in a mobile treatment unit, it offers significant advantages in cost and coordination over offsite high temperature incineration. Additionally, this project will yield information regarding applicability of eBeam technology to effectively achieve ex-situ remediation of PFOS and PFOA at sites that have other organic contaminant mixtures. The project will also yield practical information about the technical feasibility of using eBeam technology for remediating PFASs and co-contaminants in IDW. An initial assessment of technology costs for a transportable eBeam technology platform suggests that this technology will likely present a feasible alternative to currently available IDW disposal methods. (Anticipated Completion - March 2019)