The overall objective of this project is to bench-mark the performance of a recently commercialized surface-modified organo-clay adsorbent (Fluorosorb [FS]) for the removal of per- and polyfluoroalkyl substances (PFAS) and co-occurring chemicals at the pilot-scale as compared to that of representative granular activated carbon (GAC) and ion exchange (IX) products. A secondary objective of this project is to evaluate different hybrid configurations of FS, GAC, and IX to improve the overall PFAS removal performance by mitigating the impact of competitive adsorbates (e.g., dissolved organic matter), and perform an economic comparison of GAC, IX and FS, and GAC-IX versus FS-IX. Specifically, the project team hypothesizes that FS will achieve similar PFAS removal performance as IX at a cost comparable to GAC treatment. Additionally, a hybrid configuration of FS-IX will significantly elongate media replacement compared to GAC-IX based on water processed before PFAS breakthrough.
Potential drawbacks of FS will be evaluated during this study including media longevity (e.g., permeability), leaching of constituents from FS media, and the removal of co-occurring chemicals (e.g., fuel hydrocarbons, halogenated solvents) in aqueous film-forming foam-impacted groundwater. Here, two different impacted groundwaters will be targeted for the investigations and it is believed that conducting such an assessment can provide substantial guidance to the Department of Defense (DoD) for selecting PFAS treatment processes. The preliminary laboratory-scale experiments have shown promising results for FS with respect to PFAS removal indicating that the framework holds potential for mitigating current and future liabilities associated with PFAS-impacted groundwater at DoD facilities.
A pilot-scale demonstration will be conducted to investigate the objectives outlined above. To accomplish this, experimental work will entail the following:
- Comprehensive side-by-side comparison of FS to GAC and IX with a focus on removal of PFAS and common co-occurring chemicals. The project leverages previous research and existing testing infrastructure to answer the following significant question: Is FS a superior and more cost-effective option than GAC and IX for treatment of groundwater at DoD sites?
- Evaluation of FS, which is cost competitive with GAC, in a hybrid configuration with IX. Here, elongated operation of a contactor in series approach will be compared with the common GAC-IX configuration. While FS has shown great promise in laboratory-scale testing, questions remain regarding its robustness during long-term operation. Demonstration-scale will be performed to collect data (e.g., energy use, chemical use, waste production, etc.) necessary for life-cycle costing (LCC).
- Comparative assessment based on LCC. Based on data gathered and generated during the course of the study, LCC will be conducted to rank the effectiveness of selected treatment approaches and identify the best treatment scenarios (stand-alone and/or hybrid configuration) with respect to multiple metrics (treatment capability for both a range of PFAS and co-occurring chemicals), cost, disposal, etc.).
The majority of studies on novel sorbents have been carried out at bench-scale employing synthetic solutions. Although it is important to quantify performance under simplified conditions, performance of these sorbents under real environmental conditions remains relatively unknown. Currently, an unbiased and comprehensive assessment of a promising adsorbent, FS, for PFAS at pilot- and full-scale is lacking. FS is relatively new to the market and the past laboratory-scale research at Colorado School of Mines has indicated significant advantages over GAC and IX for PFAS removal. However, there are no long-term comparative assessments of FS to GAC and IX at conditions relevant to DoD sites, and currently, no unbiased assessment of FS. This project is designed to generate necessary data for DoD to determine if there are advantages of FS as an alternative to GAC or IX based on performance (removal of PFAS and co-occurring chemicals) and costing metrics. Additionally, this project is cost-effective as the pilot-scale equipment required for the comparative assessment is already constructed and the performance verified and will develop a considerable amount of relevant treatability and costing data to aid in treatment selection.