PFAS and DOM removal using an organic scavenger and PFAS-specific resin: Trade-off between regeneration and faster kinetics

Treatment technologies such as ion exchange (IX) process exhibit promising potentials for the removal of toxic per- and poly-fluoroalkyl substances (HAS) from natural waters. In recent years, industries have started manufacturing PFAS-specific resins which are typically operated in a single use-and-dispose mode until exhaustion. However, this increases the resin demand and the consequent operational cost and environmental burden of the IX process. In this study, the performance of a PFAS-specific resin (A592) was compared with that of a regenerative organic scavenger resin (A860) which is traditionally employed for dissolved organic matter (DOM) and micorpollutant removal, Comparative studies were performed to examine the removal of multiple long- and short-chain carboxylic, sulfonic, precursor and emerging PFAS (including GenX) from synthetic and natural waters. The A592 resin exhibited faster uptake kinetics for PFAS while simultaneously removing 10-15% of DOM. The A860 resin removed similar to 60-70% of DOM; however, it required approximately 3-fold higher contact times for achieving the same degree of PFAS removal when compared to the PFAS-specific resin. The resin breakthrough (C-treated (PFAS) > 70 ng/L) was observed around 125,000 +/- 5000 bed volumes (BVs) for the PEAS-specific resin (via multiple loading tests), while it ranged between 15,000-27,000 BVs for the organic scavenger. Yet, a mass balance on PFAS and DOM removal indicated similar to 90-98% site saturation (in milli-equivalents (meqs)) on both IX resins before exhaustion. More importantly, the regenerated organic scavenger resin (A860) exhibited PEAS and DOM removal capabilities for longer operational BVs when compared to A592 operated in a single use-mode in natural waters. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Treatment technologies like ion exchange show potential in removing toxic PFAS from natural waters, but the use of PFAS-specific resins can lead to increased resin demand and operational costs. Comparative studies found that PFAS-specific resin had faster uptake kinetics for PFAS and removed some DOM, while regenerative organic scavenger resin required longer contact times for PFAS removal. Despite differences in resin breakthrough, both IX resins showed similar levels of PFAS and DOM removal before exhaustion.