Removal Of PFAS Precursor Compounds Using GAC

Removal of PFAS PrecursorCompounds Using GACEric ForresterDevelopment Engineer, Drinking Water SolutionsE: fforrester@calgoncarbon.comP: 412-787-6821

RESEARCH GOALSDEVELOP DATA SET FOR PFAS PRECURSOR REMOVAL RSSCTs – well-established method, relatively quick to run Target compounds: 4 fluorotelomers & 1 sulfonamide Compare multiple carbon types (5) PFOA & PFOS included in “background”BETTER UNDERSTAND ROLE OF CARBON PROPERTIES Can pore volume distribution explain results? Can more “simple” test methods correlate to results?

PREVIEW – RESULTS - 14:2 Fluorotelomer Sulfonic Acid

PREVIEW – RESULTS - 2

PREVIEW – RESULTS - 3

PFAS OVERVIEWWHAT ARE PFAS? Poly- and perfluoroalkyl substances Class of man-made fluorinated compoundsPFOS MoleculePFOA MoleculeHealth Advisory:70 pptCombinedPFOA / PFOSWHY ARE THEY A PROBLEM? Contaminates drinking water and food Highly persistent / resistant to degradation Accumulate in the bodyWHERE DO THEY COME FROM?PFAS are used in a variety of products as asurface-active agent

PFAS Molecular CharacteristicsC-F BondCHEMICALLY STABLE Carbon Chain backbone C-F BondC-C BondCarboxylic AcidHead GroupLOW VAPOR PRESSUREPFOA MOLECULESulfonic AcidHead GroupPFOS MOLECULERELATIVELY HIGH MOLECULAR WEIGHTEASILY INFILTRATES INTOGROUNDWATER & SOILBIOACCUMULATES IN ORGANISMS

PFAS PRECURSORS4:2 Fluorotelomer Sulfonic Acid(4:2 FTS)8:2 Fluorotelomer Sulfonic Acid(8:2 FTS)6:2 Fluorotelomer Sulfonic Acid(6:2 FTS)Perfluorooctane Sulfonamide

PFAS TREATMENT TECHNOLOGYTREATMENT OPTIONPROS Significantly lower capital costsSignificantly lower O&M costsReactivation saves cost, destroys PFASs, &removes liabilityEstablished BAT for a long list of organiccontaminantsROCONS Removes salts / inorganics that GAC cannot Resin can be regeneratedMay be more economical at highconcentrations of PFAS (generally much higherthan drinking water applications – primarilyremediation applications only) High Natural Organic Matter (NOM) canincrease use ratesRemoval efficacy varies bysize/weight/solubility of contaminantConcentrated waste water disposalliabilities & costsMore energy / CO2 intensiveHigh maintenance cleaning andreplacement of fouled membranesRemoves healthy mineralsHigh cost of mediaRegeneration produces disposalliabilities & costsRegeneration requires both brine and asolvent (e.g. methanol)

STRUCTURE OF ACTIVATED CARBONAdsorptionPoresTransportPores Calgon Carbon Corporation 2018 Slide 10 Finest pores in structure Termed “micropores” 20Å diameter Diffusion pathways totransport adsorbates Termed “mesopores” 20Å - 500 Å diameter

CALGON CARBONPFAS TREATMENT LOCATIONSLARGE EQUIPMENT INSTALLATIONSPOINT OF ENTRY TREATMENT INSTALLATIONS40 INSTALLATIONS ACROSS THE US

TREATMENT METHODOLOGYDUAL VESSEL TREATMENT Maximize carbon loading Simplify carbon exchange logistics RedundancySUFFICIENT CONTACT TIME IS CRITICAL FOR EFFECTIVE REMOVAL Kinetics and Thermodynamics of adsorption must be considered 10 minutes EBCT per vessel minimum

REMOVAL STUDYRSSCTsGACDETAILSFive GAC products evaluated underidentical equivalent full-scale operatingconditions and influent water qualityGAC Source MaterialFull-ScaleMesh SizeApparentDensityIodine Number(mg/g)Xylenol Orange DyeNumber (mg/g/hr)MolassesNumberReagglomeratedBituminous Coal - Virgin12 400.543103013.5189ReagglomeratedBituminous Coal – React.12 400.54690513.4236Lignite Coal12 400.37760517.4416Sub-Bituminous Coal12 400.350101521.7154Coconut Shell12 300.414129013.5288

GAC COMPARISONTEST CONDITIONS - 1OPERATING PARAMETERS 10 minutes empty-bed contact time (EBCT). Pennsylvania groundwater spike with PFAS.Compound4:2 Fluorotelomer Sulfonic Acid6:2 Fluorotelomer Sulfonic Acid8:2 Fluorotelomer Sulfonic AcidPerflurooctanesulfonic AcidPerflurooctanoic AcidPerflurooctane SulfonamideAbbreviation4:2 FTS6:2 FTS8:2 FTSPFOSPFOAPFOSAAvg. InfluentConcentration (ng/L)130435615317739

GAC COMPARISONTEST CONDITIONS - 2WATER QUALITYComponentpHTotal Dissolved SolidsAlkalinityTotal Organic CarbonValue8.16701050.3Unitsmg/Lmg/L as CaCO3mg/L

REFRESHER: READINGBREAKTHROUGH CURVESREMEMBER Usually shown asnormalized values. C/Co - What isinfluentconcentration? “Bed Volumes”does not equalactual run time.

PFAS BREAKTHROUGH CURVESREAGGLOMERATED BITUMINOUS GAC (VIRGIN)

PFAS BREAKTHROUGH CURVESLIGNITE-BASED GAC

PFAS BREAKTHROUGH CURVES4:2 FTS

PFAS BREAKTHROUGH CURVES6:2 FTSShort-term spikeIn feed concentrations

PFAS BREAKTHROUGH CURVES8:2 FTSShort-term spikeIn feed concentrations

PFAS BREAKTHROUGH CURVESPFOS

PFAS BREAKTHROUGH CURVESPFOA

PFAS BREAKTHROUGH CURVESPFOSAShort-term spikeIn feed concentrations

INITIAL CONCLUSIONSALL 4 PRECURSORS REMOVABLE WITH GAC 4:2 FTS most difficult‒ Lower molecular weight (shorter chain).‒ Large variation in removal.‒ Most-favorable performance with reaggl. bituminous GACs.SENSITIVITY TO VARYING INFLUENT CONCENTRATIONS Reaggl. bituminous GAC minimally affected.Sub-bituminous & enhanced coconut showed rapid increasein breakthrough during spike.Some sensitivity evident in lignite breakthrough curve.

PROPERTIES vs.PERFORMANCEIn addition to surrogate adsorbate tests,porosity of test GACs was evaluated usingnitrogen adsorption isotherms andcompared to performance.4:2 FTSREMOVALGAC Source MaterialBV to 50%BreakthroughApparentDensityIodine Number(mg/g)Xylenol Orange DyeNumber (mg/g/hr)MolassesNumberReagglomeratedBituminous Coal - ous Coal – React.150,5000.54690513.4236Lignite Coal36,2000.37760517.4416Sub-Bituminous Coal38,6000.350101521.7154Coconut Shell38,8000.414129013.5288

GAC POROSITY: 5 - 500 ÅParking LotsHighways

GAC POROSITY: 5 - 100 ÅParking LotsHighways

GAC POROSITY: NORMALIZED TO VOLUME IN BEDDramatic shiftsin relativeamounts ofporosity.

GAC POROSITY: HOW MUCH IS IN THE BED?

GAC POROSITY: RELATED TO PERFORMANCE?Key is porosity pervolume, not perweight!

IODINE NUMBER: RELATED TO PERFORMANCE?Does not accountfor variation indensity of GACs.

NORMALIZED IODINE NUMBER: RELATED TO PERFORMANCE?Normalized toactual volume ofcarbon in bed.

IODINE & DYE NUMBER COMBINED: RELATED TO PERFORMANCE?GAC Source MaterialApparentDensityIodine Number(mg/g)Xylenol Orange DyeNumber (mg/g/hr)ReagglomeratedBituminous Coal - Virgin0.543103013.5ReagglomeratedBituminous Coal – React.0.54690513.4Lignite Coal0.37760517.4Sub-Bituminous Coal0.350101521.7Coconut Shell0.414129013.5AD x (0.1 x Iodine 3.2 x Dye Number)

CONCLUSIONSPRECURSORS ARE REMOVABLE ALONG WITH PFOA & PFOS Compound structure impacts removal as expectedGAC performance varies widely among source materialsReactivated GAC can offer performance on-par, or nearly on-par, withits virgin counterpart, depending on the target contaminantGAC SELECTION MUST CONSIDER INTERPLAY BETWEEN PROPERTIES No single specification can adequately guide carbon selectionPorosity is key, but only when considered alongside bed density“Old” methods such as Iodine Number are still valuable, especially whencombined with some measure of adsorption rate, such as Dye Number

Thank you for your time.Questions?Eric Forresterfforrester@calgoncarbon.com412-787-6821 Calgon Carbon Corporation 2018 Slide 36

Breakthrough Apparent Density Iodine Number (mg/g) Xylenol Orange Dye Number (mg/g/hr) Molasses Number Reagglomerated Bituminous Coal - Virgin 206,300 0.543 1030 13.5 189 Reagglomerated Bituminous Coal –React. 150,500 0.546 905 13.4 236 Lignite Coal 36,200 0.377 605 17.4 416 Sub-Bituminous Coal 38,600 0.350 1015 21.7 154 Coconut Shell 38,800 .