TABLE 1.

High-level summary of various PFAS management technologies

Technology		Advantages	Disadvantages
Concentration	Reverse osmosis and nanofiltration	• Effective removal • Small footprint • Relatively energy-efficient	• Membrane scaling limits recovery
	Membrane distillation	• Effective removal of PFPeA	• Membrane fouling • Very early research stage • High thermal energy use
	Forward osmosis	• High rejection and recovery possible	• Draw regeneration difficult
	RO-electrodialysis hybrids	• Possibly concentrate charged PFAS compounds	• No validation with PFAS
	Foam fractionation	• Effective removal of long-chain PFAS, including PFOS	• Less effective for short-chain PFAS
	Electrocoagulation	• Ease of operation • Effective removal of PFOA and PFOSwith Zn anode	• Requires optimization ofoperational conditions • Passivation of electrode material
	Evaporation ponds	• Compatible with solar energy	• High land area requirement
		• ZLD possible	• PFAS emissions to air possible
	Brine concentrators and crystallizers	• Significant concentration and ZLD possible	• High energy requirement • PFAS emissions to air possible
	Adsorption	• Reliable and easy to operate	• May require frequent regeneration and/or replacement of saturatedadsorbents
	Coagulant aids	• Early data show high effectiveness	• Proprietary formulations
Defluorination	Biological treatment	• Could scale well	• Largely unsuccessful so far
	Ultraviolet irradiation	• Availability of equipment	• Ineffective for PFAA
	Photocatalysis	• Effective degradation of PFOA • Reduce energy consumption by using visible light	• May generate intermediates, such as PFHpA, PFHxA, PFPeA, PFBA, PFPA, and TFA • Proof-of-concept stage
	Advanced oxidation	• Moderate success with FTOHs	• Limited success with PFAS
	Hydrated electrons	• Effective destruction of at least some PFAS	• Early stage
	Plasma-based treatment	• Early evidence of effective defluorination	• Early stage
	Electron beam	• High technology readiness level: previously used at full and pilotscales for wastewater and groundwater and commercially available in medical and pasteurization industries	• Large capital cost and high priceper volume treated • Needs further research onmembrane concentrate to understand matrix interferences
		• Effective at PFOA and PFOS degradation
	Zero-valent iron	• Effective with carbonate PFAS	• Less effective with sulfonate PFAS
	Sonochemical treatment	• Complete mineralization of PFAS can be achieved without any pretreatment	• High energy input and scalability issues
	Incineration	• Effective in desorption/destruction of PFAS	• Formation of by-products
	Supercritical water oxidation	• Effective with many PFAS • Demonstrated at scale with PFAS-laden groundwater and leachate	• High temperature and pressure create operational challenges
		• Salts in membrane concentrates must be removed to prevent severescaling
Sequestration	Deep-well injection	• Reliable sequestration	• Nondestructive
	Landfill	• Endpoint for solids	• Nondestructive • Impermanent sequestration due toPFAS-laden leachate production

Note: For references, see the relevant section of the narrative.

Abbreviations: FTOHs, fluorotelomer alcohols; PFAA, perfluoroalkyl acid; PFAS, per- and polyfluoroalkyl substances; PFBA, pentafluorobenzoic acid; PFHpA, perfluoroheptanoic acid; PFHxA, perfluorohexanoic acid; PFOS, perfluorooctane sulfonic acid; PFPeA, perfluoropentanoic acid; PFPA, perfluoropropanoic acid; RO, reverse osmosis; TFA, trifluoroacetic acid.