Formatted Title
Integrated Remediation of Cr(VI) and PFAS Contaminants in Chrome-Plating Facilities
Background/Objectives
Background/Objectives. In recent years, there has been a significant rise in chrome-plating facilities taking remedial action independently or under regulatory guidance. Many of these facilities are commingled sources of per- and polyfluoroalkyl substances (PFAS) and hexavalent chromium (Cr(VI)) due to their use in the plating process. The co-occurrence of these contaminants presents unique challenges to in situ remediation, yet careful amendment selection and a clear understanding of treatment mechanisms can assist in developing effective remedial plans from bench studies to field implementations.
Approach/Activities
Approach/Activities. One approach to manage commingled Cr(VI) and PFAS plumes is the application of sulfidated micro-scale zero-valent iron (S-MZVI) and colloidal activated carbon (CAC): ZVI to treat Cr(VI) via immobilization or reduction to Cr(III), and CAC to immobilize PFAS. Additional methodologies will be presented including biological treatment added for Cr(VI) or chlorinated compounds. Both single mobilization treatments and remediation using multiple-phase treatment trains will be presented. Data have been compiled including early and intermediate monitoring results, along with an analysis of the type of remedial applications and selection considerations. Additionally, the potential for interference from each of the two co-occurring treatment processes was investigated on the bench scale.
Results/Lessons Learned
Results/Lessons Learned. A series of bench-scale scale tests were performed to determine if the presence of Cr(VI) and/or Cr(III) would have a measurable effect on the adsorption of PFAS by CAC. Results of the bench-scale showed that when Cr(VI) and PFAS were treated together, there was significant to complete removal of both contaminants. It was observed that the presence of field-relevant concentrations of Cr(VI)/Cr(III), whether reduced by ZVI or not, had little to no effect on the adsorption of PFAS in the CAC. By carefully considering the remedial needs of each contaminant type and observing the challenges associated with complex applications, a good understanding of future design types and project needs has been obtained.