Sustainable Groundwater Remediation
Mentor: Dr. Michelle Crimi
Department: Institute for a Sustainable Environment
The historical use of aqueous film forming foam (AFFF) formulations containing perfluorinated compounds (PFCs) for firefighting and training activities at DoD sites has led to concern over the potential for contamination of groundwater at up to 600 sites. Because regulatory guideline concentrations for PFCs are 3-4 orders of magnitude lower than concentrations measured to date at several Air Force sites, cost effective in situ groundwater treatment approaches are needed that consider the unique chemical properties of PFCs (high solubility, low volatility, emulsification behavior, recalcitrance, and presence as mixtures). The objective of this proposed work is to develop a predictable and low cost in situ treatment train for remediating perfluoroalkyl contaminated groundwater toward expedited closure of Department of Defense (DoD) sites. Our approach takes advantage of the key features of two current best practices for treatment of perfluoroalkyl contaminated water, sorption onto granular activated carbon (GAC) and destruction using activated persulfate oxidation, while overcoming key limitations of each. We propose to evaluate the feasibility, effectiveness, and sustainability of a treatment train approach where activated carbon is used to sorb and concentrate contaminants in situ, followed by contaminant destruction and carbon regeneration in situ using activated persulfate. This approach is termed in situ chemical oxidation of sorbed contaminants (ISCO-SC). We will also identify oxidation intermediates and byproducts toward understanding limitations of ISCO for treatment of PFCs and the need for additional coupled processes, and the amenability of intermediates and byproducts to biological treatment using computer-based prediction tools. We will evaluate the feasibility, effectiveness, and sustainability of a treatment train approach where activated carbon is used to sorb and concentrate contaminants in situ, followed by contaminant destruction and carbon regeneration in situ using heat activated persulfate for the long-term, semi-passive treatment of PFCs, common co-contaminants, and/or other AFFF additives. We will also identify intermediates and byproducts of oxidation of PFCs and common precursors and co-contaminants. We will develop a tool to help determine longevity of carbon and regeneration time under varied site conditions, and we will evaluate the tool effectiveness using soil and groundwater collected from field sites. Finally, we will conduct a conceptual design level analysis of cost and sustainability relative to other potentially viable treatment approaches for a portfolio of PFCs-contaminated sites.