FMC Chemicals Ltd Wirral International Business Park, Commercial Road, Bromborough, Wirral, CH62 3NL Tel: +44 1514827356 www.environmental.fmc.com

Ian Ross Ph.D, Mike Mueller and Philip Block Ph.D. (FMC Environmental Solutions)

FMC, Klozur, EHC, ISGS, DARAMEND, TERRAMEND, and PermeOx are registered trademarks

of the FMC Corporation. Copyright ©2012 FMC Corporation. All rights reserved. 21-01-EIT-DL

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0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

log

MP

N/g

so

il

Time (weeks)

Control

Dose 1

Dose 2

Dose 3

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 formation after 30 weeks

*[HgS]=203 μg/kg if all Hg precipitated as cinnabar.

0.0

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0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Time (weeks)

Su

lfid

e C

on

c. (m

g/L

as

S)

Control

Dose 1

Dose 2

Dose 3

Sulfide Production

• No MeHg producedKlozur® CR oxidized all contaminants in a sediment high in NOM (>14%)

• Native SRB survived the highest dose (20 g/kg) and thrived soon afterwards

• SRB produced sulfide within weeks

• >80% of Hg precipitated as HgS after 30 weeks

Conclusions

• Activated Persulfate is a strong oxidant used for in situ and ex situ destruction of contaminants in soil and

groundwater

• Provides the strength of “Fenton’s Chemistry” but with extended subsurface lifetime (3 – 4 months) and little to

no heat or gas evolution

• Applicable across a broad range of organic contaminants

• Activation produces a radical which is powerful and kinetically fast

• Effective activation method is based on contaminant, site lithology, and hydrogeology

Chlorinated Solvents PCE, TCE, DCE TCA, DCA Vinyl chloride Carbon tetrachloride Chloroform Chloroethane Chloromethane Dichloropropane Trichloropropane Methylene chloride

TPH BTEX GRO DRO ORO creosote

Oxygenates MTBE TBA

Chlorobenzenes Chlorobenzene Dichlorobenzene trichlorobenzene

Phenols phenol Pentachlorophenol nitrophenol

Freons

Pesticides DDT Chlordane Heptachlor Lindane Toxaphene MCPA Bromoxynil

PAHs Anthracene Benzopyrene Styrene Naphthalene Pyrene Chrysene trimethylbenzene

Others Carbon disulfide PFOS / PFOA Aniline PVA TNT / DNT

Examples of Contaminants Destroyed by Klozur Persulfate

ian.ross@fmc.com +44 7855745531

The application of in-situ chemical oxidation (ISCO) technologies, which are based on the delivery of oxidising agents to contaminated source zones in order to oxidise contaminants into harmless end products within the soil mass, is a promising method for remediation of multiple contaminants. Typical oxidants used traditionally have included potassium permanganate, hydrogen peroxide (Fenton’s reagent) and ozone. Each of these oxidants has it’s limitations (e.g. persistence, reactivity etc.) within a soil matrix. Klozur® persulfate (Na2S2O8) is a more recent addition to the list of possible oxidants for use within ISCO applications and possesses multiple advantages as compared to more traditional oxidants.

1. Direct Oxidation:

2. Radical Formation

S2O8-2 + 2H+ + 2e- 2HSO4

-1

A stoichiometric equation can be derived e.g. for PCE

2S2O8-2 + C2Cl4 + 4 H2O 2CO2 + 4Cl- + 4H+ + 4HSO4

-1

3 kg / kg

S2O8-2 + activator SO4•- + (SO4•- or SO4

-2)

persulfate anion

Kinetically Fast (Reaction Kinetics with Contaminant) Capable of Destroying Wide Range of Contaminants Increases solubility of contaminants in water Temperature Range: 35 – 45º C

Heat

Heat

H2O2

High pH

Iron

Chelated Iron Slower Reaction Kinetics (Extends Persulfate Lifetime in Subsurface) Capable of Destroying: Chlorinated Ethenes, BTEX, PAHs, MTBE Target in Groundwater: 75 – 100 ppm soluble Fe

Kinetically Fast (Reaction Kinetics with Contaminant) Capable of Destroying Wide Range of Organics Benefit of two powerful radical species. Typical Concentration Ratio: 5:1, moles peroxide : mole persulfate

Hydrogen Peroxide

Kinetically Fast (Reaction Kinetics with Contaminant) Capable of Destroying Wide Range of Organics pH between 10.5 – 12 (maintained while the Klozur is present) Pre-treatment titration is needed to determine the soil’s buffering capacity

NaOH

Klozur ® Persulfate PermeOx® Plus

+

• ISCO for 2 – 3 months • self-activating high pH persulfate • residual sulfate to stimulate anaerobic bioremediation of hydrocarbons

S2O82- → SO4·- , OH·-

• slow release of oxygen for up to one year • stimulate aerobic bioremediation

CaO2 + 2 H2O → H2O2 + Ca(OH)2

2 H2O2 → O2 + 2 H2O

“Klozur CR (Combined Remedy)”

Klozur® persulfate can destroy all organic compounds dissolved in water, however the kinetics of this reaction can be controlled using differing activators. Examples of differing organic contaminants that Klozur ® persulfate can mineralise are presented below, however further compounds such BTEX, TCA, TCE, PCE, pharmaceuticals and pesticides can also be mineralised.

Introduction In Situ Chemical Oxidation ad Bioremediation The application of in-situ chemical oxidation (ISCO) will cause destruction of organic compounds, so it will also cause some micro-organisms to be killed in locations where the oxidant is distributed. However, the oxidant does not distribute throughout he whole aquifer formation, groundwater containing micro-organisms will flow back in to the oxidised zone and microbial populations are very resilient as they are often present as biofilms and encapsulated in exopolysaccharides, glycoprotein and glycolipids. Thus microbial growth in aquifers following application of ISCO is commonplace and there is usually a bacterial recolonisation event following oxidation which occurs as subsurface conditions are more favourable as a results of an increase of terminal electron acceptors, such s oxygen, sulfate, ferric iron etc. After ISCO the residual sulfate and oxygen from persulfate can be used by aerobic or sulphate reducing bacteria to continue to biodegrade any residual hydrocarbons . The addition of both oxygen and/or sulfate as remedies for petroleum hydrocarbon impacted soil and groundwater are well know technologies, so the benefits of theses terminal electron acceptors following oxidation can be exploited to allow further contaminant destruction. With this in mind FMC evolved a novel product where activation of persulfate is promoted using Permeox Plus which comprises calcium peroxide to promote high pH activation and also releases oxygen to promote aerobic biodegradation. The product is called Klozur CR (combined remedy) which comes as a solid which can de dissolved in water and injected into the subsurface.

Treatment Train Approach

groundwater flow

Injection well

monitoring well

Source Zone

Down gradient plume

ISCO applied first in source zone

Bio applied in plume

Properties • formulated as a slurry • pH ~ 11

Typical Application • Direct push injection • Emplacement (excavations, barrier walls)

Target Compounds • TPH, BTEX, MTBE, PAHs • Chlorobenzene, Phenols etc.

Single Product to add to water and inject, provides both ISCO and Bioremediation

ISCO Bioremediation

Impact of ISCO on Sulfate Reducing Bacteria (SRBs) 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 • 4 g Klozur / kg sediment • 10 g Klozur / kg sediment • 20 g Klozur / kg sediment

Dose MeHg1

(%)

PCB2

(%)

PAH2

(%)

NOM

(%)

Dose 1 >99.96 31 27 22

Dose 2 >99.96 59 61 37

Dose 3 >99.96 91 88 43

% reductions from control

1 time= 5-10 days

2 time= 4-8 weeks

A study of the ability of Klozur persulfate to degrade recalcitrant organic compounds including PCB’s and PAH’s in addition to methyl mercury (MeHg), was performed using contaminated sediments in a stirred tank reactor (pictured above). The higher dose of persulfate caused significant contaminant destruction. However, following treatment the microbial population in the reactor was monitored and sulphate reducing bacteria were seem to recolonise the reaction vessel. The sulphide produced from biological activity also complexed the mercury, removing it from solution.

MPN of Sulfate Reducing Bacteria (SRB)

• Activated persulfate will not sterilize soil / groundwater • 20 – 30% initial drop in microbial population observed for both aerobic and anaerobic species • Rebound of microbial species observed, sometimes greater than initial concentrations • Cell utilization of contaminant substrate will be influenced but not halted • Calcium peroxide – activated persulfate is effective on TPH / BTEX compounds • SRB’s can be stimulated by residual sulfate

Conclusions