1,4-Dioxane as well as per- and polyfluoroalkyl substances (PFASs) are among the most persistent environmental chemicals, severely challenging currently available remediation technologies. Moreover, these chemicals of concern (COCs) often co-occur in mixed plumes at DoD sites. Building on previous work, the objective of this research is to advance the efficacy of electrolytic water treatment for the remediation of groundwater impacted by mixed COCs, focusing on PFASs and 1,4-dioxane in the presence of chlorinated solvents.
The treatment approach will create and utilize synergistic effects between two processes within a single treatment system: (1) rapid anodic oxidation on novel, dimensionally stable electrode materials, and (2) stimulation of aerobic biodegradation processes via electrolytically generated oxygen and concurrent removal of inhibiting co-occurring chemicals. This research is divided into the following tasks:
- Electrode Development and Testing (leveraged through funding by DuPont & Chemours Gift to Colorado State University): Development and characterization of novel tin-based mesh electrodes with subsequent performance and stability (i.e., service life) testing.
- (2-4) Treatment of Mixed PFAS, 1,4-Dioxane and Chlorinated Solvent impact: Simulating conditions representative of aquifers and aboveground treatment reactors, laboratory-scale flow-through column reactor studies will be conducted. Electrolytic, biological, and combined electrobiostimulated degradation performance for PFASs, 1,4-dioxane, and mixed PFASs/1,4-dioxane will be assessed. In addition, the impact of chlorinated solvents will be tested as these often co-occur with PFASs and 1,4-dioxane and may inhibit their biodegradation.
This research builds on the project team’s progress on earlier DoD research efforts, including “Sequential Electrolytic Degradation of Energetic Compounds in Groundwater” (SERDP ER-1234), “Electrically Induced Redox Barriers for In Situ Treatment of Groundwater” (ESTCP ER-200112), “Field Demonstration/Validation of Electrolytic Barriers for Energetic Compounds at Pueblo Chemical Depot” (ESTCP ER-200519), “In Situ Biodegradation of 1,4-Dioxane: Effects of Metals and Chlorinated Solvents” (SERDP ER-2300), and “Bioaugmentation with Vaults: A Novel In Situ Remediation Strategy for Transformation of Perfluoroalkyl Compounds” (SERDP ER-2422).
Currently, remediation of groundwater impacted with the highly persistent 1,4-dioxane and PFASs typically requires costly ex situ advanced oxidation processes, and in situ technologies are either limited or completely lacking. In this project, the researchers will endeavor to develop a practical and more cost-effective solution for managing mixed COC impact. The testing of various performance-impacting parameters in combination with previously gained experiences in field implementation will ultimately provide DoD site managers with financial and technical guidance on treatment options and design for specific remedial goals. (Project Completed - 2021)
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