Evaluation and Life Cycle Comparison of Ex-Situ Treatment Technologies for Per- and Polyfluoroalkyl substances (PFASs) in Groundwater
Dr. Kenan Ozekin | Water Research Foundation
Currently, an unbiased and comprehensive assessment of the various perfluoroalkyl substance (PFAS) treatment technologies is lacking. Such an assessment is needed to provide guidance to the Department of Defense (DoD) for selecting PFAS treatment processes. To fill this information gap, an experienced project team has been assembled that seeks to generate the data necessary to compare, on a life-cycle assessment (LCA) and costing (LCC) basis, established and emerging PFAS treatment approaches. The objectives of this project include:
a) Development of a comprehensive assessment framework for ex-situ PFAS treatment technologies. Based on data gathered and generated during the course of the study, a LCA and LCC will be conducted to compare the effectiveness of various treatment scenarios using multiple metrics (e.g., treatment capability, cost, environmental and human health impacts). This framework is needed to develop effective strategies for ex-situ PFAS remediation.
b) Generation of a PFAS treatment efficiency database to support development of a decision support tool. Efforts will focus on collecting and generating treatment data for established and emerging treatment processes for the removal and/or destruction of PFASs in aquifers impacted by aqueous film forming foam (AFFF) and common co-contaminants. The technologies selected for the database will represent state-of-the-science approaches for PFAS treatment. The team will collect existing data and augment the developed database with information gained from laboratory scale experiments.
c) Development of a treatment technology decision support tool with stakeholder input. While certain technologies have been touted as effective for certain PFASs, each approach has limitations depending on site-specific contamination, treatment goals, and a myriad of other factors. Currently, there is little guidance on the selection of treatment processes for site-specific goals. Efforts will focus on gathering input from various stakeholders via a workshop and ultimately the development of a decision support tool for the selection of treatment approaches based on the developed assessment framework.
The established treatment technologies to be included in the decision support tool include granular activated carbon (GAC), ion exchange (IX), GAC followed by IX, and nanofiltration or reverse osmosis (NF/RO). The emerging treatment technology that will be tested is superfine powdered activated carbon (sPAC) with separation by ceramic microfiltration (MF). The team will review current and ongoing related research on destructive technologies (i.e., electrochemical, non-thermal plasma and UV-sensitized treatment processes) for treatment of residuals (i.e., IX regenerant, RO/NF concentrate) to assess readiness levels and inclusion in the treatability study. Slight modifications to these treatment approaches will be considered pending the results of on-going research efforts, including current Air Force Civil Engineering Center (AFCEC) and Strategic Environmental Research and Development Program (SERDP) research efforts.
There has been a significant number of recent publications proposing the treatment of PFASs through a variety of methods . While some technologies show promise for certain PFASs, little work comparing the benefits and liabilities of the various treatment options has been performed. Moreover, unbiased side-by-side comparison of PFAS treatment technologies is required to perform an LCA on various treatment approaches. The goal is to vet the most promising technologies being touted as effective for PFAS treatment. Improved insight into the life-cycle feasibility of various technologies for the ex-situ removal of a variety of PFASs and co-contaminants from dilute groundwater plumes will facilitate the adoption of appropriate technologies at DoD sites and provide guidance to the broader water treatment community.