Theme: 07. Per- and Polyfluorinated Alkyl Substances (PFAS)

Topic Area: 7d. Ex Situ PFAS Water Treatment Technologies

Formatted Title:

Application of High Recovery Membrane Systems for the Separation of PFAS

Background/Objectives:

The implementation of separation-based treatment technologies for PFAS-impacted liquids is generally limited by throughput, decreased performance for short-chain PFAS, uncertainty regarding future PFAS regulations, and treatment residual management considerations. Applications of high-pressure membrane systems address many of the challenges facing separation-based PFAS treatment technologies with the notable exception of treatment residuals management. However, emerging high-recovery, high-pressure membrane systems mitigate some of these concerns and can serve as critical elements of successful integrated PFAS treatment solutions.

The objective of this study was to investigate the PFAS rejection performance of high-pressure membranes spanning a range of selectivity in a full-scale pilot system operating at 97% recovery; resulting in a concentrated liquid residual representing 3% of the treated volume.

Approach/Activities:

In this study, four commercially available high-pressure membranes (NF270, NF90, CR100, and SW30) spanning the loose NF to tight RO separation ranges were investigated for their PFAS rejection performance. The specific focus was devoted to evaluating the removal of perfluoroalkyl acids (PFAAs) in a full-scale closed-circuit desalination (CCD) pilot module operating at 97% recovery. The results of these membrane evaluations were compared based on standard performance metrics (e.g., conductivity rejections), PFAA rejection, and estimated specific energy consumption.

Results/Lessons Learned:

Results from this study indicate that tight NF and RO membranes can be used to concentrate PFAS streams by a factor of 33 (97% recovery) with very low permeate PFAA concentrations. The application of high-recovery, high-pressure membrane systems in integrated treatment train approaches has the potential to significantly increase the resiliency of PFAS treatment systems against the evolving regulatory landscape and enhance the viability of achieving PFAS destruction.

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