Enhanced Removal of Long- and Short-Chain PFAS from Source Water via Hybrid Green Sorption Media-Nanofiltration (GSM-NF)

Limitation of conventional remediation technologies Granular activated carbon (GAC) Reverse osmosis and nanofiltration Limited capacity High energy requirements Expensive High capital cost Disposal of spent carbon Sensitivity to fouling Non-selective Concentrate disposal Ion exchange Chemical Oxidation Limited capacity Limited application Sensitive to fouling Expensive Expensive Production of byproducts 7 Research objectives Investigating the effects of green-sorption media (GSM) pretreatment on NF of long- and short-chain PFAS Understanding the impact of GSM-pre-treated water matrix properties on NF membrane performance Mechanisms of PFAS removal by green sorption media and the subsequent nanofiltration (NF) 8 Membrane ID XN45 Membrane Type Nanofiltration Manufacturer TriSep Polymer Polypiperazine-amide MWCO (Da) Contact angle (degree) 57 ± 1a Zeta potential at pH 5.5(mV) -25a Isoelectric point (IEP) 4a Rejection (%) 95% MgSO Flux (GFD)/psi 35/110 pH range 2-11 a (Hallé, 2023) a (Hallé, 2023) 13 Experimental set up for individual system Influents ZIPGEM CPS Centrifugal Pump Peristaltic pump Retentate Retentate Valve Feed Tank Feed tank Column effluents evlaV ssapyB Pressure Gauge Permeate CF042 cell Inlet SCALE SCALE PC SCALE Flowmeter Recirculating Chiller Experimental set up of pretreatment units (a) and nanofiltration system (b) M. Experimental aspects Summary of experimental aspects Removal efficiencies of long-chain and short-chain PFAS by both GSM Removal efficiencies of perfluoroalkyl sulfonic acids (PFSAs) and perfluoroalkyl carboxylic acids (PFCAs) by both GSM Removal efficiency via any of the hybrid systems (CPS-NF and ZIPGEM-NF) and the control. Removal efficiencies of membrane in hybrid system and that of the control. Concentrations of TOC, DOC and Ca2+ in the raw canal water and the GSM-pre-treated water. 16 Effect of GSM pretreatment on NF 100 80 60 40 20 PFBA PFBS PFOA PFOS 19 lavomeR % CPS-NF ZIPGEM ZIPGEM-NF CPS Control Control 45 40 35 30 0 5 10 15 20 Time (h) )1-h2-mL( xulf etaemreP a) Removal efficiencies of selected PFAS in different treatment system. b) Permeate flux decline in nanofiltration membrane Hence, when the pretreatment media fails to remove PFAS effectively (e.g., shortchain PFAS, upon media exhaustion), the membrane plays a significant role in the overall removal efficiency. GSM pretreatment can not only offer PFAS removal from source waters, but also serve as a costeffective and sustainable means of reducing NF membrane fouling/scaling by removing NOM and cations from water. 23 Biofiltration in Drinking Water Treatment: Reduction of Membrane Fouling and Biodegradation of Organic Trace Contaminants. Continuous fixed-bed column adsorption of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) from canal water using zero-valent Iron-based filtration media.