Treatment of Emerging Contaminants with Activated Persulfate - PowerPoint PPT Presentation

Treatment of Emerging Contaminants with Activated Persulfate Philip Block, PhD FMC Corporation

Agenda • Brief overview of persulfate chemistry • PFOA and PFOS • 1,4-dioxane • Metals (mercury and arsenic)

Activated Persulfate Chemistry • Activated persulfate has been used for over twelve years to treat contaminated soil and groundwater • “activation” needed to form highly reactive radical species 2.6 eV -2 + activator  SO4• - + (SO4• - or SO 4 -2 ) S 2 O 8 One of strongest Heat Iron H 2 O 2 High pH oxidants available.

Activated Persulfate Chemistry • Reactive species SO 4 · - sulfate radical OH· - hydroxyl radical O 2 · - superoxide • robust, multi-prong attack on contaminant • can treat a wide range of organic contaminants

PFOA / PFOS • PFOS is a recalcitrant xenobiotic which is persistent, bio-accumulative & toxic • Use in fire fighting foams (AFFF), Scotchguard ™ etc. • ISCO developed as aggressive solution for in situ destruction of PFOS

PFOA / PFOS Peer-Reviewed Literature Chen, et al, “ Photodegradation of Perfluorooctanooic Acid in Water Under Irradiation of 254 nm and 185 nm Light by Use of Persulfate”, Water Science and Technology 54, p 317, 2006 Hori, et al, “Efficient Decomposition of Environmentally Persistent Perfluorocarboxylic Acids by Use of Persulfate as a Photochemical Oxidant”, Environ Sci Technol 39, p 2383, 2005. Liu, et al, “Effect of Temperature on Oxidative Transformation of Perfluorooctanoic Acid (PFOA) by Persulfate Activation in Water” Separation and Purification Technology , in print, 2011. Lee, et al, “Microwave -hydrothermal Decomposition of Perfluorooctanoic Acid in Iater by iron- activated Persulfate Oxidation” Water Research 44, p 886, 2010. Hori, et al, “Persulfate -induced Photochemical Cecomposition of a Fluorotelomer Unsaturated Carboxylic Acid in Water”, Water Research 41, p 2962, 2007. Kingshott , “Remedial Approaches for Perfluorooctane Sulfonate ”, master’s thesis, Imperial College London, 2008.

Study Outcomes UV activated persulfate destruction of PFOA Chen PFOA rapidly destroyed by UV activated persulfate. Intermediates observed. February 4, 2014

Study Outcomes Hori UV activated persulfate destruction of PFOA PFOA rapidly destroyed by UV activated persulfate. Intermediates observed. February 4, 2014

Study Outcomes Lee Modest results on PFOA using heat and microwave radiation. Increased performance upon addition of ZVI. February 4, 2014

Study Outcomes Heat and high pH activated persulfate destruction of PFOS Kinshott Heat and hydrogen peroxide activated persulfate rapidly destroyed PFOS. Alkaline activation had much slower kinetics. February 4, 2014

FMC Lab Data on PFOS Destruction PEN Value = 21 Day Results % contaminant destroyed / % PFOS Reduction persulfate used 0.7 0.8 2.3 0.7 1.1 4.3 38 51 22 0.8 0.8 0.8 90 80 70 60 % PFOS Reduction 50 Low Medium 40 High 30 Low: 1 x 20 Medium: 2 x 10 High: 10 x 0 FeEDTA Fe + H2O2 high pH heat Control PFOS concentration: 985 mg/L Klozur persulfate dosing: 1, 2, 10 x stoichiometric amount Room temperature, DI water February 4, 2014

1,4-dioxane • primary use as a stabilizer for 1,1,1-TCA • highly water soluble (miscible) • resulting 1,4-dioxane plume may be larger than TCA plume • analytical detection is difficult • US EPA lists as probable carcinogen • Prop 65 (California) lists as a cancer causing agent February 4, 2014

1,4-dioxane  US EPA Listed Health Advisory for Dioxane at a Drinking Water Concentration of 3 ppb (µg / L)  Several EPA Regions and States Have Developed Guidelines for Dioxane  In 2004, Colorado First State to Establish Enforceable Standard for Dioxane in Groundwater Type of Guidance Matrix Concentration Type of Guidance Matrix Concentration State or Region State or Region Risk based Conc’s EPA Region 3 Tap water 6.1 ppb Generic cleanup 350 ppb - Ind Michigan criteria and DW Human health 85 ppb - Res screening levels EPA Region 6 medium specific Tap water 6.1 ppm screening levels Missouri Target Conc. GW 3 ppb Preliminary New Hampshire DW 3 ppb EPA Region 9 Tap water 6.1 ppb remediation goals North Carolina GW 7 ppb Health based California DW 3 ppb Medium specific advisory levels 5.6 ppb (A) concentrations for 24 ppb (B) Water quality GW & 6.1 ppb Pennsylvania organic regulated GW Colorado 56 ppb (C) (3.2 ppb March ‘10) standard surface water substances in 240 ppb (D) groundwater Uniform risk based Delaware remediation GW 6 ppb Drinking water standards South Carolina regulation and DW 70 ppb health advisory Soil cleanup target Florida GW 3.2 ppb levels Protected 18.6 ppb - Ind Texas concentration GW Maximum exposure 8.3 ppb - Res Maine DW 3.2 ppb levels guideline Massachusetts DW 3 ppb Risk based Conc’s West Virginia DW 6.1 ppb A = used aquifer / residential; B = used aquifer / non residential; C = nonuse aquifer / residential; D = nonuse aquifer / non residential February 4, 2014

Study Outcomes Site: active warehouse in Piedmont of NC vadose and saturated zones in sand / silt / clay Contaminants: TCA (200 ppm), DCE (82 ppm), 1,4-dioxane (50 ppm) Treatment train: combination of steam (target 45 C) and lime 30 injection points inside building 60 injection points outside injected 100,000 lbs of Klozur Site Location: North Carolina 1,4 Dioxane Treatment by Catalyzed Sodium Persulfate Monitoring Wells Dioxane concentration (ug/L) John Haselow Pre Treat Post Treat % Reduction MW-1 50,000 < 5 99.9% MW-7 3220 < 5 99.8% MW-14 3020 < 5 99.8% MW-17 3400 Non Detect 100% February 4, 2014

Study Outcomes Paul Dombrowski February 4, 2014

Study Outcomes 180,400 lb of Klozur persulfate injected over 3 events High pH activation (followed by peroxide application) February 4, 2014

Metals • oxidants generally are thought to have a negative impact on nascent metals in groundwater • changes in groundwater quality (pH, ORP, DO) can change metal mobility • however, long term change in mobility is not observed post ISCO application once groundwater returns to background conditions • can activated persulfate be used to reduce soluble metal concentrations? February 4, 2014

Example for Mercury W. Michigan Lab Study Prof. Dan Cassidy • contaminated sediments from Kalamazoo River • initial contaminant loadings • 7720 mg/kg PCB • 9063 mg/kg PAHs • 175 ug/kg total Hg • study incorporated 3 dosages: persulfate activated with calcium peroxide Stirred tank reactor • 4 g / kg sediment • 10 g / kg sediment • 20 g / kg sediment February 4, 2014

Example for Mercury MPN of Sulfate Reducing Bacteria (SRB) 8 7.5 7 log MPN/g soil 6.5 Control 6 Dose 1 5.5 Dose 2 5 Dose 3 4.5 4 3.5 3 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Time (weeks) February 4, 2014

Example for Mercury Sulfide Production 400.0 Sulfide Conc. (mg/L as S) 350.0 300.0 Control 250.0 Dose 1 200.0 Dose 2 150.0 Dose 3 100.0 50.0 0.0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Time (weeks) February 4, 2014

Example for Mercury HgS formation after 30 weeks [HgS] ( μg/kg )* Dose % total Hg Control 22.5 11.1 Dose 1 104.7 51.6 Dose 2 135.2 66.6 Dose 3 169.7 83.5 *[HgS]=203 μ g/kg if all Hg precipitated as cinnabar. February 4, 2014

Example for Arsenic • Laboratory study investigating combination of persulfate and zero valent iron (ZVI) to reduce soluble arsenic • DI water containing 20 – 100 mg/L As(III) was spiked into silty sand soil under nitrogen. ~ 30% of As spike was lost due to adsorption onto soil after 60 hours of contact time • water to soil ratio: 50 g soil to 100 mL of spiked water Grams of Reagent Addition to 300 g of Soil 10:1 persulfate : ZVI Sample Id. Sodium Zero valent Na 2 PO 4 persulfate iron 0.24 – 1.8 wt% active CTL 0 0 0 to soil R1L 0.6 0.06 0 R1H 1.5 0.15 0 R2L 0.6 0.06 0.06 R2H 1.5 0.15 0.15 February 4, 2014

Example for Arsenic February 4, 2014

Summary • activated persulfate can treat a wide range of contaminants • emerging contaminants can readily be treated with activated persulfate • PFOS / PFOA • 1,4-dioxane • MTBE (not presented here) • Nitrosamines (not presented here) • pharmaceuticals / endocrine disrupters (not presented here) • activated persulfate has been shown to have a positive effect on the reduction of aqueous concentrations of certain metals February 4, 2014

Questions Philip Block, PhD FMC Global Peroxygens 215-299-6645 philip.block@fmc.com February 4, 2014