Per‐ and polyfluoroalkyl substances (PFAS), which are present in many waters, have detrimental impacts on human health and the environment. Reverse osmosis (RO) and nanofiltration (NF) have shown excellent PFAS separation performance in water treatment; however, these membrane systems do not destroy PFAS but produce concentrated residual streams that need to be managed. Complete destruction of PFAS in RO and NF concentrate streams is ideal, but long‐term sequestration strategies are also employed. Because no single technology is adequate for all situations, a range of processes are reviewed here that hold promise as components of treatment schemes for PFAS‐laden membrane system concentrates. Attention is also given to relevant concentration processes because it is beneficial to reduce concentrate volume prior to PFAS destruction or sequestration. Given the costs and challenges of managing PFAS in membrane concentrates, it is critical to evaluate both established and emerging technologies in selecting processes for immediate use and continued research.Article Impact Statement: Readers will benefit from learning about established and emerging management approaches for per‐ and polyfluoroalkyl substances and the peculiarities of their application to reverse osmosis and nanofiltration concentrates.

Granular activated carbon (GAC) is a commonly used technology for removal of per- and polyfluoroalkyl substances (PFAS). However, most studies characterizing PFAS absorption to GAC are performed in small bench-scale tests with synthetic groundwater, which poorly approximates conditions encountered in full-scale treatment systems. Pilot-scale studies, although somewhat rare, better predict full-scale performance due to realistic operating conditions. This study presents breakthrough results from a pilot-scale GAC system operated for seven months treating a continuous source of PFAS contaminated groundwater with four activated carbons, Calgon F400 and F600, and Norit GAC400 and GCN1240. Chain length dependent breakthrough was generally observed for perfluorocarboxylates (PFCAs) and perfluorosulfonates (PFSAs) where shorter chain PFASs broke through faster than longer chain PFASs. All tested GACs performed similarly for weakly adsorbing shorter chain PFASs, suggesting that GAC properties may not affect breakthrough for these PFASs. However, F400 and GAC400 performed 40–50% better than F600 and GCN1240 for strongly adsorbing long chain PFASs, which may be due to a higher volume of transport pores within F400 and GAC400. Breakthrough curves were fit by equilibrium and intraparticle diffusion models using the solid liquid partition coefficient (K_d). The equilibrium model was found to be a better fit for the data and a more practical model. Model K_d outputs from the pilot study were compared against a separate batch study. Comparisons showed that batch study K_d values were larger for longer chain compounds and smaller for shorter chain compounds.

Toxic per- and polyfluoroalkyl substances (PFAS) are now found in nearly every water source on the planet. Exposure to these molecules can have negative health consequences, but the low concentration of PFAS relative to other solutes in water makes their removal challenging. Adsorbents offer a promising treatment route, but often exhibit low selectivities and removal capacities, as well as slow kinetics. The performance in these metrics can be improved by chemically optimizing PFAS binding sites and maximizing PFAS-adsorbent interactions. To explore how to achieve this, a porous polymer network solid (PPN-6, also known as PAF-1) was postsynthetically modified with various chemical moieties capable of leveraging unique combinations of electrostatic, hydrogen-bonding, hydrophobic, and fluorophilic interactions with PFAS molecules. Batch adsorption experiments and computational studies revealed that electrostatic and hydrogen-bonding interactions drive short-chain PFAS adsorption, while hydrophobic and fluorophilic interactions improve long-chain PFAS adsorption. In complex water matrices, a combination of electrostatic and fluorophilic interactions led to the greatest total PFAS removal. The best-performing material, functionalized with a fluorinated alkylammonium (PPN-6-FNDMB), selectively adsorbs PFAS with high capacity (up to 4.0 mmol/g) and rapid kinetics (equilibrium reached in <30 s). Furthermore, PPN-6-FNDMB outperforms several commercial adsorbents, achieving near-complete removal of 21 different PFAS from a groundwater sample collected at a US Air Force base. The PFAS could subsequently be desorbed from PPN-6-FNDMB, concentrating them by a factor of over 50 times. The recycled PPN-6-FNDMB could then be reused with minimal losses in long-chain PFAS adsorption capacity over four cycles.