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

S2O8

• 2 + activator  SO4•- + (SO4•- or SO4
• 2)

Heat Iron H2O2 High pH 2.6 eV One of strongest

• xidants

available.

Activated Persulfate Chemistry

• Reactive species

sulfate radical SO4·- hydroxyl radical OH·- superoxide O2·-

• 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

• f 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.

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Study Outcomes

Chen UV activated persulfate destruction of PFOA

PFOA rapidly destroyed by UV activated persulfate. Intermediates observed.

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Hori UV activated persulfate destruction of PFOA

PFOA rapidly destroyed by UV activated persulfate. Intermediates

• bserved.

Study Outcomes

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Lee

Modest results on PFOA using heat and microwave radiation. Increased performance upon addition of ZVI.

Study Outcomes

February 4, 2014

Study Outcomes

Kinshott Heat and high pH activated persulfate destruction of PFOS

Heat and hydrogen peroxide activated persulfate rapidly destroyed PFOS. Alkaline activation had much slower kinetics.

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FMC Lab Data on PFOS Destruction

10 20 30 40 50 60 70 80 90

FeEDTA Fe + H2O2 high pH heat

% PFOS Reduction

PFOS Reduction

Low Medium High

Low: 1 x Medium: 2 x High: 10 x 21 Day Results Control PFOS concentration: 985 mg/L Klozur persulfate dosing: 1, 2, 10 x stoichiometric amount Room temperature, DI water

PEN Value = % contaminant destroyed / % persulfate used

0.7 0.8 2.3 0.7 1.1 4.3 38 51 22 0.8 0.8 0.8

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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

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• 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

State or Region Type of Guidance Matrix Concentration EPA Region 3 Risk based Conc’s Tap water 6.1 ppb EPA Region 6 Human health medium specific screening levels Tap water 6.1 ppm EPA Region 9 Preliminary remediation goals Tap water 6.1 ppb California Health based advisory levels DW 3 ppb Colorado Water quality standard GW & surface water 6.1 ppb (3.2 ppb March ‘10) Delaware Uniform risk based remediation standards GW 6 ppb Florida Soil cleanup target levels GW 3.2 ppb Maine Maximum exposure guideline DW 3.2 ppb Massachusetts DW 3 ppb State or Region Type of Guidance Matrix Concentration Michigan Generic cleanup criteria and screening levels DW 350 ppb - Ind 85 ppb - Res Missouri Target Conc. GW 3 ppb New Hampshire DW 3 ppb North Carolina GW 7 ppb Pennsylvania Medium specific concentrations for

• rganic regulated

substances in groundwater GW 5.6 ppb (A) 24 ppb (B) 56 ppb (C) 240 ppb (D) South Carolina Drinking water regulation and health advisory DW 70 ppb Texas Protected concentration levels GW 18.6 ppb - Ind 8.3 ppb - Res West Virginia Risk based Conc’s DW 6.1 ppb A = used aquifer / residential; B = used aquifer / non residential; C = nonuse aquifer / residential; D = nonuse aquifer / non residential

1,4-dioxane

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Study Outcomes

Site Location: North Carolina 1,4 Dioxane Treatment by Catalyzed Sodium Persulfate Monitoring Wells Dioxane concentration (ug/L) 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% 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

John Haselow

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)

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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
• bserved 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

• 4 g / kg sediment
• 10 g / kg sediment
• 20 g / kg sediment

Stirred tank reactor

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Example for Mercury

MPN of Sulfate Reducing Bacteria (SRB)

3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 log MPN/g soil Time (weeks)

Control Dose 1 Dose 2 Dose 3

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Example for Mercury Sulfide Production

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

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HgS formation after 30 weeks

Dose [HgS] (μg/kg)* % 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 μg/kg if all Hg precipitated as cinnabar.

Example for Mercury

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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

Sample Id. Grams of Reagent Addition to 300 g of Soil Sodium persulfate Zero valent iron Na2PO4 CTL R1L 0.6 0.06 R1H 1.5 0.15 R2L 0.6 0.06 0.06 R2H 1.5 0.15 0.15 10:1 persulfate : ZVI 0.24 – 1.8 wt% active to soil

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Example for Arsenic

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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