In Situ Chemical

Reduction of

Chlorinated

Compounds

Josephine Molin

Technical Sales Manager

Air Pollution Control

FMC offers SOx and NOx abatement product technologies for coal-fired plants.

Natronx, LLC, EnProveTM sodium sorbents are engineered to remove SO2, SO3, HCl and HF

from stack gases.

FMC’s patented PerNOxide™ technology, licensed from NASA, uses H2O2 to oxidize nitrogen

oxide (NO) and elemental mercury (Hg˚) in flue gas into forms that can be captured by flue-

gas scrubbing devices.

Soil and Groundwater Remediation

FMC’s Klozur® persulfate, Daramend® bioremediation technology, and the EHC® family

of integrated carbon & ZVI technologies, are available globally to provide cost effective

solutions for the remediation of contaminated soil, groundwater, and sediments.

Water Treatment

FMC VigorOx® peracetic acid is a safe and environmentally-benign biocide. FMC can work

directly with customers to understand their unique challenges and develop turnkey solutions

tailored to meet their specific treatment needs while ensuring compliance with individual

state regulations. Our proven water treatment applications include the wastewater and the

oil services industries.

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ISCR Groundwater

Remediation

Technologies

EHC® family of integrated

carbon & ZVI technologies for

in situ chemical reduction

EHC® ISCR Reagent Composition

EHC is delivered as a dry powder and

includes the following:

• Micro-scale zero valent iron (standard ~40%)

• Controlled-release, food grade, complex

carbon (plant fibers) (standard ~60%)

• Major, minor, and micronutrients

• Food grade organic binding agent

• Sustainable Solution:

o scrap metal

o food production by-products

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Contaminants Treated

EHC® ISCR Reagent

• Chlorinated Solvents

o PCE, TCE, cDCE, 11DCE, VC

o 1122TeCA, 111TCA, 12DCA

o CT, CF, DCM, CM

• Pesticides

o Toxaphene, Chlordane, Dieldrin, Pentachlorophenol

• Energetics

o TNT, DNT, RDX, HMX, Perchlorate

EHC®-M ISCR Reagent for Metals

• Heavy Metals including As, Cr, Pb, Zn, Cd

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Mechanism Material Description

Direct Chemical Reduction

ZVI

•Redox reaction at iron surface where solvent gains electrons and iron donates electrons

•Abiotic reaction via beta-elimination

Indirect Chemical Reduction

ZVI •Surface dechlorination by magnetite and green rust precipitates from iron corrosion

Stimulated Biological Reduction

Carbon Substrate

•Anaerobic reductive dechlorination involving fastidious microorganisms

•Strongly influenced by nutritional status and pH of aqueous phase

Enhanced

Thermodynamic Decomposition

ZVI + Organic Carbon

•Energetics of dechlorination are more favorable under lower redox conditions generated by combination of ZVI and organic carbon

EHC® ISCR Treatment Mechanisms

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Direct Dechlorination Reactions

Figure

Courtesy P.

Tratnyek,

Oregon

Graduate

Institute

Reactions:

Fe0 Fe2+ + 2e-

2H2O 2H+ + 2OH-

2H+ + 2e- H2(g)

R-Cl + H+ + 2e- R-H + Cl-

Carbon Fermentation + ZVI Corrosion:

Multiple Dechlorination Mechanisms

Production of organic acids (VFAs):

•Serves as electron donor for microbial

reduction of CVOCs and other oxidized

species such as O2, NO3, SO4

•The release of acids keeps the pH down

and thereby serve to reduce precipitate

formation on ZVI surfaces

Favorable thermodynamic conditions

for dechlorination:

•Combined oxygen consumption from

carbon fermentation and iron oxidation

Strongly reduced environment

•High electron/H+ pressure

Corrosion H2 generation

Dissolved iron precipitates as reactive

minerals

Hydrocarbon generation

Material

Solid

Organic

Carbon

Iron

Metal

Oxide Film

Ferm

enta

tion

H+

VFA

Downgradient effects

• EHC zone of influence may significantly exceed the direct placement

zone.

• Elevated levels of TOC and Fe and changes to ORP has been

measured up to 70 ft away from the injection zone advection may

be a very important distribution mechanism at some sites.

Solid Particle Bacteria

• Low redox

• Controlled pH

• VFAs, Nutrients

• Ferrous iron

• Hydrogen

ß–Elimination: Main Pathway

Biogenolysis/Hydrogenolysis: Minor Pathway

• Reaction is abiotic reductive dehalogenation; minimizes/eliminates DCE/VC

• Requires direct contact with ZVI surface

• β-elimination is the dominant abiotic pathway (~90%); ZVI generates hydrogen so

some biotic reductive reactions are supported

Direct Chemical Reduction

CVOC Dechlorination Pathways with ZVI

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EHC® ISCR Installation Methods

Injection Methods

• Direct injection

• Hydraulic fracturing

• Pneumatic fracturing

• Well injections (EHC-L)

Direct Placement

• Trenching

• Excavations

• Deep soil mixing

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EHC Installation Methods – Direct Placement

Installation of EHC PRB

Placement at bottom of excavation to

treat standing groundwater.

EHC® ISCR Installation Methods

Direct Injection & ChemGrout Mixing

ChemGrouts CG-500 used for mixing and

injections (rated at 20 GPM at 1,000 psi).

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Preparation of slurry using grout mixer

EHC mixed with water into 30% slurry.

Injection probe with check valve

Allows for either top-down or

bottom-up injection and directs

the slurry laterally into the

subsurface.

A key feature of this probe is that it acts

as a backflow preventer, keeping injection

material IN the ground and not ON the

ground!

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EHC Conceptual Designs

Source Area/

Hotspot Treatment

Injection PRB for

Plume Control Plume

Treatment

- Dosing: 0.15 to 1% wt/wt

- Spacing: 2 to 5m (DPT)

- Dosing: 0.4 to 1% wt/wt

- Spacing: 2 to 3 m (DPT)

- Dosing: 0.05 to 0.2% wt/wt

-Line Spacing: depends on

linear gw velocity

EHC Case Study – Source Area Treatment

Former Dry Cleaner, Oregon

• Primary CVOCs included chlorinated

ethenes at concentrations up to:

– PCE ~ 22,000 ug/L

– TCE ~ 1,700 ug/L

– DCE ~ 3,100 ug/L

– VC ~ 7 ug/L

• Site-Specific Challenges:

– Low permeability lithology – high degree

of sorbed impacts expected

– Large seasonal variation in groundwater

table (range from ca 2.1 to 4.6 m bgs)

2.5 m smear zone

– Groundwater flow direction change with

season

Test Injection – EHC Injection Distribution Validation

EHC

injection

point

Sampling

locations

Test Injection Soil Cores with EHC Fractures

Injection layout and sampling locations

Figure from Hart Crowser.

-A total of 10,000 lbs (4,649 kg) of EHC was injected into 32 injection points

targeting an area measuring 77 m2 x 6 m deep (from 3 to 9 m bgs).

-Application rate of 0.6% EHC to soil mass.

Source Area Treatment

Results - EHC® Indicator Parameters

0

500

1,000

1,500

2,000

2,500

3,000

0 3 6 9 12 15 18 21 24 27 30 33 36 39

Conc.

(mg/L

)

Time post EHC injection (months)

Total Organic Carbon

0

20

40

60

80

100

120

140

0 3 6 9 12 15 18 21 24

Conc.

(mg/L

)

Time post EHC injection (months)

Ferrous Iron

NW sampling cluster NE sampling cluster

SW sampling cluster SE sampling cluster•Sharp increase in TOC and Fe(II) following injections

confirms effective product placement.

•Dissolved concentrations have gradually decreased over

time but remain above background levels.

•TOC ranging from 3.3 to 18.6 mg/L after 40 months, which

is above the baseline range of <0.8 to 1.8 mg/L.

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Source Area Treatment Results

Redox indicator parameters

NWsamplingcluster

NEsamplingcluster

SWsamplingcluster

SEsamplingcluster0

510152025303540

0 5 10 15 20 25 30 35 40

Conc.

(mg/L

)

Time post EHC injection (months)

Sulfate

0

5

10

15

20

25

0 5 10 15 20 25 30 35 40

Conc.

(mg/L

)

Time post EHC injection (months)

Methane

-300-250-200-150-100-50

050

100150

0 5 10 15 20 25 30 35 40

OR

P (

mV

)

Time post EHC injection (months)

ORP

0

1

2

3

4

5

6

0 5 10 15 20 25 30 35 40

Conc.

(mg/L

)

Time post EHC injection (months)

Dissolved Oxygen

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Source Area Treatment Results

CVOCs

0

2,000

4,000

6,000

8,000

1 5 8 12 14 18 22 24 31 34

Conc.

(ug/L

)

Time post injections (months)

SE sampling cluster

0

2,000

4,000

6,000

8,000

10,000

12,000

1 5 8 12 14 18 22 24 31 34

Conc.

(ug/L

)

Time post injections (months)

SW sampling cluster

0

5,000

10,000

15,000

20,000

25,000

30,000

-18 0 1 5 8 12 14 18 22 24 31 34

Conc.

(ug/L

)

Time post injections (months)

NW sampling cluster

0

1,000

2,000

3,000

4,000

5,000

6,000

-18 0 1 5 8 12 14 18 22 24 31 34

Conc.

(ug/L

)

Time post injections (months)

NE sampling cluster

VC

CA

c-DCE

TCE

PCE

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25

Total CVOCs and Fluctuations in

Groundwater Table 0

1

2

3

4

5

6

7

8

9

101

10

100

1,000

10,000

100,000D

ec-0

6

Ap

r-0

7

Au

g-0

7

Dec

-07

Ap

r-0

8

Au

g-0

8

Dec

-08

Ap

r-0

9

Au

g-0

9

Dec

-09

Depth

to G

roundw

ate

r (m b

gs)

Tota

l C

VO

C C

onc.

(ug/L

)

CVOCs - NW CVOCs - NE CVOCs - SW CVOCs - SE

GW Table - NW GW Table - NE GW Table - SW GW Table - SE

Max: 151 ppb

Max: 54 ppb

Max: 418 ppb

Source Area Treatment

Degradation End Products

0

100

200

300

400

500

600

700

800

0 3 6 9 12 15 18 21 24 27 30 33 36 39

Co

nc.

(ug

/L)

Time post EHC injection (months)

Ethene - NW

Ethane - NW

Ethene - NE

Ethane - NE

Ethene - SW

Ethane - SW

Ethene - SE

Ethane - SE

•An increase in ethene and ethane levels confirms that complete dehalogenation is occurring.

•Ethene levels of up to 760 ug/L were measured in July 2007 (11-month data) 96 percent increase

compared with maximum baseline levels.

•A correlation has been observed between total CVOC concentrations and ethene plus ethane measured

in groundwater following an initial acclimatization period of 7 months.

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Economics

• A total of 10,000 lbs of EHC was applied at a product cost of $20,000.

• The material cost of using EHC was $1.24/ft3 ($44/m3).

• The injections were completed in 5 days.

• Results of this pilot study have shown that ISCR using the EHC technology offers a safe, effective and cost-efficient remedial solution for dry cleaning and related sites.

• Plume extends 2,600 ft / 800

m from grain elevators.

• Discharges into small creek.

• The bedrock rises to an

elevation of ca 9 ft / 3 m above

the present day water table at

the presumed source area.

• PRB installed down-gradient of

suspected source area in April

2005.

• The PRB is installed as a line

of injection points spaced

approximately 10 ft / 3 m

apart.

• The PRB extends across the

width of the plume and

measures ca 270 ft / 90 m

long.

EHC® PRB Case Study

Plume Treatment Carbon Tet Site - Kansas

Figure courtesy of Malcolm Pirnie Inc.

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-50

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

0 27 54 81 108 135 162 189 216 243 270

Distance from SBE [ft]

Inje

cti

on

de

pth

[ft

]

EHC® PRB – Plume

Treatment Injection Layout

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44<1

<1

120067

25<1 <1

19

1575

16

72<1

5.825

<1

EHC Treatment Zone

Monitoring well andCT concentration (ug/L)

N

Property Line

0 300 600

SCALE IN FEET

May 2010

60<1

<1

57062

31<1 <1

21

1635

21

120<1

1334

<1

EHC Treatment Zone

Monitoring well andCT concentration (ug/L)

N

Property Line

0 300 600

SCALE IN FEET

October 2009

70<1

<1

1400130

29<1 <1

21

2117

62

260<1

1589

<1

EHC Treatment Zone

Monitoring well andCT concentration (ug/L)

N

Property Line

0 300 600

SCALE IN FEET

April 2009

150<1

<1

620170

49<1 <1

37

1254

110

490<1

28170

<1

EHC Treatment Zone

Monitoring well andCT concentration (ug/L)

N

Property Line

0 300 600

SCALE IN FEET

October 2008

82<1

<1

1400300

57<1 <1

13

1946

380

650<1

25280

<1

EHC Treatment Zone

Monitoring well andCT concentration (ug/L)

N

Property Line

0 300 600

SCALE IN FEET

April 2008

98<1

<1

1600170

27<1 <1

14

94140

610

540<1

82190

<1

EHC Treatment Zone

Monitoring well andCT concentration (ug/L)

N

Property Line

0 300 600

SCALE IN FEET

August 2007

36<1

<1

2700620

33<1 <1

17

150380

610

410<1

2.485

<1

EHC Treatment Zone

Monitoring well andCT concentration (ug/L)

N

Property Line

0 300 600

SCALE IN FEET

February 2007

47<1

<1

770140

100011 <1

140

49067

280

4606.4

3798

<1

EHC Treatment Zone

Monitoring well andCT concentration (ug/L)

N

Property Line

0 300 600

SCALE IN FEET

March 2005

EHC® PRB - Plume Treatment Results

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EHC® PRB – Plume Treatment Economics

• A total of 48,000 lbs / 21,800 kg of

EHC was used to create the 270 ft / 90

m long PRB at a product cost of less

than $100,000 $37/ft2 ($395/m2) of

PRB cross-section.

• The installation was completed in 12

days using direct injection.

• So far, the PRB has treated a total of

ca. 2,500,000 ft3 (73,000 m3) of

groundwater during its life-time at a

product cost of $0.04/ft3 ($1.32/m3).

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EHC®-L – Soluble ISCR Reagent

• EHC -L is a cold-water soluble formulation

of EHC specially designed for injection via

existing wells or hydraulic injection networks.

• EHC -L is delivered in two parts:

(i) a liquid organic carbon emulsion and

(ii) an organo-iron powder.

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Part 2

Part 1

• Water content will vary with

desired injection volume and

physical conditions.

EHC-M Controlled-release carbon with sulfide, nutrients & micro-scale ZVI

EHC®–M ISCR Reagent for Metals

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• Reducible metals are

present in natural waters as

anions and oxyanions (e.g.

Cr, As, Se, Mo, U)

• Immobilized via reductive

precipitation with iron

oxides and oxyhydroxides

• Puls and Su, EPA Research

Lab, OK:

Reductive precipitation of

chromium and arsenic

treatment with ZVI PRBs.

Previous Research on In-situ Reductive

Treatment of Dissolved Metals

• Metal cations are present in

natural waters as divalent

cations (e.g. Cu, Zn, Cd, Pb,

Hg, Ni)

• Precipitate as metal sulfides.

• Various carbon substrates used

to microbially mediate

reduction of sulfate present in

the groundwater

• Blowes et al., University of

Waterloo: Organic substrate

PRBs for sulfate reduction and

trace metals treatment in acid

mine drainage.

Amended aquifer

zone.

Solid carbon

source could be

saw dust, wood

chips, plant

fibers.

Previous Research on In-situ Reductive

Treatment of Dissolved Metals

EHC-M Composition

Contains controlled-release organic carbon, micro-scale zero valent iron (ZVI), a source of sulfate and other additives

Treats dissolved trace metals and mixed plumes containing cVOCs and metals

Summary of Treatment Efficiencies

Observed in Internal Lab Tests

Compound Influent

Concentration Range (ug/L)

Observed Removal Efficiency (%)

Antimony 24,500 >99

Arsenic 500 98

Cadmium 11 >99

Chromium 200 >99

Cobalt 210 >99

Copper 86 >99

Lead 64,000 >99

Nickel 350 >99

Zinc 50,400 92

November 5, 2012

www.environmental.fmc.com

Josephine Molin

Technical Sales Manager

FMC Environmental Solutions

Phone: 773.991.9615

josephine.molin@fmc.com

www.environmental.fmc.com

Any Questions?

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