welcome to the science of iscr webinar · 2014. 2. 20. · origins of “iscr” tratnyek, johnson,...

Welcome to the

Science of ISCR

Webinar

hosted by,

Paul Tratnyek

James Mueller

The Science of ISCR

Paul Tratnyek (OHSU)

Jim Mueller (FMC)

IN SITU CHEMICAL REDUCTION (ISCR) Part 1. Introduction, Technical Background,

and Core Concepts

Dr. Paul G. Tratnyek, Professor

Environmental and Biomolecular Systems

Oregon Health & Science University

http://www.ebs.ogi.edu/tratnyek/

[email protected]

Origins of “ISCR”

Tratnyek, Johnson, Lowry, Brown (2014) SERDP Book Series, v7 4

In situ chemical reduction (ISCR) has been given a variety of

definitions since the term first started appearing in the late 1990s:

1. Dolfing, van Eekert, Seech, Vogan, Mueller, 2006 (5th

ChlorCon); 2008, Soil Sed. Contam. 17(1): 63-74.

– Combined C and Fe for synergistic effect

– Context for Daramend® and EHC®

– Trademark by Adventus, no longer by FMC

2. Brown et al., 2006 (5th ChlorCon); 2008 (6th ChlorCon);

2010 (SERDP Book, v5).

– Evolving definitions some emphasizing analogy to ISCO

3. Tratnyek 2010 (7th ChlorCon); 2014 (SERDP Book, v7)

– Precise, but inclusive

– Non proprietary

– Consensus

P.G. Tratnyek (OHSU)

Consensus Definition of ISCR

Tratnyek, Johnson, Lowry, Brown (2014) 5

• For the purposes of the chapter, and in general, ISCR refers to the category of in situ groundwater remediation technologies where treatment occurs primarily by chemical reduction of contaminants.

– Partially analogous to ISCO

• The emphasis of ISCR is on abiotic processes, but contaminant reduction by biogenic reducing minerals is included if the role of microbial activity in the contaminant reduction is indirect.

– Assumes a continuum from abiotic to biotic

• The reducing conditions necessary for ISCR can arise from natural “intrinsic” biogeochemical processes, or be generated by stimulation of in situ microbial activity, or be “engineered” by addition of strong chemical reductants.

– Accommodates Dick Brown’s “branches” of ISCR


State of the Practice


• SZTI (w/ nZVI):

Source zone targeted injection

• ISSM (w/ ZVI + Clay):

In soil soil mixing

• ISCR(®) (w/ Daramend® or EHC®):

In situ chemical reduction

• PRBs (w/ ZVI):

Permeable reactive barriers

• ISRM (w/ dithionite):

In situ redox manipulation

• CRD (w/ H2 + Pd):

Catalytic reductive dechlorination

• BiRD (w/ C and S):

Biogeochemical reductive dechlorination

• Abiotic MNA:

Monitored natural attenuation


NRC (2005) Contaminants in the Subsurface

Lebron, Reinhard, et al. (2007) NAVFAC

Szecsody, Fruchter, et al. (PNNL)

Technical Background: Outline

Tratnyek and Macalady (2000) 7

Reductant (reducing)

Contaminant (oxidizing)

Oxidized Reductant

Reduced Contaminant


Matrix, Medium

Four chemical aspects of remediation by ISCR:

Background: 1. Reductants

Fan et al. (2013) ES&T 47(10): 5302-5310 8

The reductants that contribute to ISCR can be divided

into two “branches”:

1. Relatively mild “intrinsic” reductants: natural minerals that

contain FeII, S−II, and/or S−I, and natural organic matter (NOM).

2. Relatively strong “engineered” reductants: dithionite (S2O42−),

zerovalent iron (ZVI) or other zerovalent metals (ZVMs).

Most of what applies to (1) may also

be involved in (2).


Add nZVI to induce sulfate reduction.

Sulfide forms FeS, which sequesters

pertechnetate as technetium sulfide.



The three types of “intrinsic” (naturally occurring), abiotic reductants

that have been studied most thoroughly are:

1. Minerals (or their amorphous analogs) that derive reducing

properties from FeII. These include magnetite, green rust,

ferruginous clays, iron oxides with adsorbed FeII, and

possibly minerals commonly associated with basalt.

2. Minerals deriving their reducing properties from S−II (or S−I) as

well as FeII. The most-studied such minerals are mackinawite

and pyrite, but other FeII and S−II/−I phases of possible

significance include greigite, marcasite, and amorphous

FeS.

3. Redox-active moieties associated with natural organic matter,

which are mainly quinones, but could also include thiol groups

and/or complexed iron.



He, Su, Wilson, et al. (EPA 600/R-09/115) 10




Engineered abiotic reductants include:

1. Zerovalent iron (ZVI)

– in SZTI, ISSM, ISCR(®), PRBs

2. Divalent iron (DVI) as “soluble iron”

3. Sulfide (H2S/HS−) or Polysulfide (CaSx foam)

4. Dithionite (hydrosulfite, S2O4=)

– in ISRM

5. Hydrogen (H2) with hydrogenation catalysts (Pd, Ni, etc.)

– in CRD

6. Organic reductants (formate, citrate, etc.)

– in BiRD



Matheson & Tratnyek (1994) ES&T 28(12): 2045-2053 12

Reductions initiated by Fe0 corrosion:

1. Reactions involving iron metal

Fe0 + 2 H2O → FeII + H2 + 2 OH-

Fe0 + ½ O2 + H+ → FeII + OH-

Fe0 + RX + H+ → FeII + RH + X-

2. Reactions involving ferrous iron

2 FeII + ½ O2 + H+ → 2 FeIII + OH-

2 FeII + RX + H+ → 2 FeIII + RH + X-

3. Other possible reactions

H2 + RX → RH + H+ + X-


Background: 1. Kinetics

Amonette et al. (2000) and Gregory et al. (2004) 13

Fe(II) adsorbed to Fe(III) oxides creates strongly reducing surface sites that can

give fairly rapid contaminant reduction. Left: carbon tetrachloride (CT) favored by

Fe(II) on goethite; Right: RDX reduction favored by Fe(II) on magnetite.



AFCEE/ESTCP (2008) Workshop 14


Background: 2. Contaminants

Tratnyek, Scherer, Johnson, Matheson (2003) 15

The processes responsible for contaminant removal by ISCR

include degradation and sequestration.

• Contaminants that are subject to degradation by reduction under ISCR

conditions include:

– Organic compounds with chloro-, nitro- or other readily reducible

functional groups (esp. chlorinated solvents; TCE etc.).

– Metal oxyanions that become less mobile upon reduction (esp.

chromate, also pertechnetate, selenate, arsenate, etc.)

– Non-metal inorganics such as nitrate and perchlorate(?).

• Contaminants that are subject to sequestration under ISCR conditions

include:

– Metal oxyanions that undergo reduction/(co)precipitate

(above, and uranyl, etc.)

– Metal cations by “cementation” (esp. Cd, Cu, Hg, Ni, Pb, etc.)


Background: 2. Contaminants



Solid arrows: hydrogenolysis

Dotted arrows: reductive elimination

Dashed arrows: hydrogenation

“Stall” Intermediates

Background: 3. Thermodynamics

Tratnyek and Macalady (2000) 17


Overall redox reaction is

sum of the half-reactions:

(Ared = AOx + e−) +

(BOx + e− = BRed) =

(ARed + BOx = AOx + BRed)

ΔErxn must be positive, so

ΔGrxn will be negative, so

rxn will be favorable

thermodynamically.

(Still may not be

favorable kinetically.)

Background: 3. Thermodynamics

Grundl et al. (2001) Aquatic Redox Chemistry, Ch. 1 18


• Redox reactions

occur between

specific oxidants

and reductants.

• Redox couples are

not in equilibrium.

• Measured Eh (ORP)

is a poor predictor of

reduction rates.

• Measured Eh (ORP)

is only a symptom,

NOT the cause.


Johnson, Scherer, Tratnyek (1996) ES&T 30: 2634-2640 19


Kinetics for ZVI are

well characterized.

kobs (half-life) is site

specific.

kM and kSA are mass

and surface area

normalized kobs.

kSA is most general

(esp. for comparison

among ZVI types).


Tratnyek et al. (1997) GWMR 17: 108-114 20


1 m2/mL is typical of batch tests. 3.5 m2/mL is typical of PRBs.


Tratnyek et al. (1997) GWMR 17: 108-114 21


For ZVI PRB,

scaling calculations

done with a simple

reactive transport

model by Jerry

Eykholt.

Assumes typical

values of kSA, ZVI

specific surface area

and dose, treatment

goal, dispersion, etc.

Background: 3. Capacity

Tratnyek (unpublished) 22


Overall success requires meeting thermodynamic,

kinetic, and “capacity” criteria.

As with ISCO, total demand =

contaminant demand + aquifer demand

Background: 4. Matrix Effects

23


Natural Reductant Demand (NRD)

(i) Ford, R.G. (2002) In: EPA Workshop on Monitoring Redox

Processes in GW; (ii) Brown, R.A. and D. Robinson (2004) In:

Proc. ChlorCon Conf. in Monterey, CA. (iii) Borda et al. (2009)

In: ACS Symp. Ser. No. 1027.

Johnson, R.L.; Nurmi, J.T.; O’Brien Johnson, G.S.; Fan, D.; O’Brien

Johnson, R.L.; Shi, Z.; Salter-Blanc, A.J.; Tratnyek, P. G.; Lowry,

G. V. (2013) Field-Scale Transport and Transformation of

Carboxymethylcellulose-Stabilized Nano Zero-Valent Iron.

Environ. Sci. Technol. 47, 1573-1580.

Tratnyek, P.G., R.L. Johnson, V.G. Lowry, and R.A. Brown. (2014) In

situ chemical reduction (ISCR). In: B.H. Kueper, H.F. Stroo , and

C.H. Ward (ed.), Chlorinated Solvent Source Zone Remediation.

SERDP and ESTCP Remediation Technology Monograph

Series, Springer, New York, in press.


Johnson et al. (2013) ES&T 47(3): 1573-1580 24


Large Tank Injection with Detailed Characterization (OHSU)

Modeling for Design and Assessment (Carnegie Mellon)


Johnson et al. (2013) ES&T 47(3): 1573-1580 25


Color change reflects “reductant demand”

Contact Information

26

Paul G. Tratnyek

• [email protected]

• http://www.ebs.ogi.edu/tratnyek/

• https://groups.google.com/forum/#!forum/tratnyek-lab

Electronic reprints:

• http://www.ebs.ogi.edu/tratnyek/temp/IscrChptr.pdf

• http://www.springer.com/series/8449/, Vol. 7

• http://www.ebs.ogi.edu/tratnyek/resources/docs/

• http://cgr.ebs.ogi.edu/iron/

• [email protected]


The Science of ISCR

Part 2

Field Applications

Jim Mueller – Chicago

[email protected]

Presentation Outline

Brief Introduction to FMC ESD

DARAMEND Original ISCR Reagent for Soil / Sediment

– Case Study #1 = DDT/DDD/DDE Toxaphene, Alabama

– Case Study #2 = TNT/DNT Toole AAP, Idaho

EHC Original ISCR Reagent for Groundwater

– Case Study #1 = Fracturing for TCE, Colorado

– Case Study #2 = PRB for CT, Kansas

Questions

FMC Environmental Solutions

We employee ca. 30 environmental professionals focused

on in situ remedial strategies

– 8 Ph.D. level scientists

– From 10 to 30 years experience

– 2 laboratories

We are the inventors and providers of various field-proven

remedial technologies

– >10,000,000 tons of soil treated

– Thousands of sites globally

FMC Environmental Solutions

We are not:

Consultants

Design Engineers

Field Operators

Remedial Contractors (drilling, geoprobe)

Our business model is to work collaboratively with

site owners, their consultants and our

construction partners to develop site-specific

solutions and strategies that are safe, effective

and cost efficient.

In Situ Chemical Reduction (ISCR)

– ISCR may be defined as “a synergistic process that

combines biotic + abiotic reactions and accelerates

treatment by creating highly reducing conditions”

– ISCR is beyond enhanced anaerobic

bioremediation/ERD

Process Amendments

Enhanced Anaerobic Degradation / ERD

Molasses, emulsified vegetable oils, sodium lactate, polylactic acid, whey, simple H release compounds

In Situ Chemical Reduction

EHC, EHC Lliquid , EHC-M, DARAMEND

FMC’s ISCR Reagents

water film

clay/organic matter agglomerate

clay platelets

mineral particle

micropore organic matter

hydrated DARAMEND®

particle colonized by native soil bacteria

bacterial cells

contaminant desorbs from binding site on soil and diffuses to DARAMEND®

particle surface

zero-valent metal particle

Significantly Lowered Redox (Eh) Potential = ISCR

Treatment Time (days)

Eh P

ote

nti

al (

mV

)

-600

-400

-200

200

400

0 5 10 15 25 20

Control ZVI or Carbon Only

EHC™

Redox potentials of -600 mV to -800 mV

Thermodynamics of reductive decomposition become favorable

Buffering capacity US Patents W.R. Grace & Company / Adventus / FMC

COIs Treated by ISCR

Chlorinated Solvents

• PCE, TCE, cDCE, 11-DCE, VC

• 1122-TeCA, 111-TCA, 12-DCA

• CT, CF, DCM, CM

Pesticides

• Toxaphene, Chlordane, Dieldrin, Pentachlorophenol, DDT/DDD/DDE

Energetics

• TNT, DNT, RDX, HMX, Perchlorate

Heavy Metals including

• As, Cr, Pb, Zn, Cd, Ni

NOT TPH, DRO, GRO (BTEX?)

• Reductive DARAMEND tilled into soil and water added to initiate

reductive phase

• Very strong reducing conditions created with Eh readings commonly

between -400 mV and -500 mV within 24 hours

• Static incubation for 5 to 10 days

• Soil tilled to initiate aerobic phase of 2 to 5 days duration = ONE

CYCLE

• Amendment composition and dosage soil specific (ZVI content/source)

TIME

ANOXIC (NEGATIVE)

OXIC (POSITIVE)

REDOX

ONE CYCLE

0

What is DARAMEND®

Treatment of Pesticides THAN Superfund Site, Montgomery, AL

Daramend® Pesticide Removal Efficiency

High Concentrations (average 6 cycles)

Contaminant Initial Concentration

(mg/kg)

Concentration After

1st Cycle (mg/kg)

Concentration After

2nd Cycle (mg/kg)

Final %

Removal

DDT 2.05 2.00 0.66 68%

DDE 2.37 1.98 0.80 66%

Dieldrin 0.110 0.080 0.028 65%

Contaminant Concentration (mg/kg)

RDE (%) Initial Final

Toxaphene 720 10.5 99

DDT 227 15 93

DDD 590 87 85

DDE 65 8.6 87

Total COC 1,602 121.1 92

Low Concentrations

59-01-EIT-DL

What was the fate of the DDT? Dechlorination (anaerobic)

From Sayles et al. (1997)

What was the Fate of the DDT? Ring opening/Mineralization?

• Radioisotope (14C-DDT) Fate Studies:

Main fate was conversion to carbon dioxide

Slow but significant production of 14C-CO2

Recovery of added 14C in DDT as carbon dioxide was about 7% in 150 days

After 150 days the rate of 14C-CO2 release had decreased to about 1% per month

• Stable isotope (13C-DDT) Fate Studies indicated dichlorobenzophenone was the major breakdown product

Tooele AAP - Utah

10,000 yd3 of impacted soil

TNT maximum concentration 2,500 mg/kg; RAO <86

RDX maximum concentration 1,000 mg/kg; RAO < 31

Tooele AAP - Utah

Effect of DARAMEND® RDX and DNT

Average TNT and RDX Results

0

100

200

300

400

500

600

700

800

900

0 0.5 1 1.5 2 2.5

Sampling Event Number

Co

ncen

trati

on

(P

PM

)

RDX (PPM)

TNT (PPM)

ca. $60/yd3

DARAMEND Treatment Cost = $16/ton (1 application)

On-site Adventus Tech Support $19,600

Equipment Rental $11,500

DARAMEND ISCR Reagent $27,700

Delivery of product and equipment $11,500

TOTAL: $70,300

*0.8 acres @ 2.5 ft bgs = 4,400 tons **Typical US costs ~$29 - $63/ton

Excavation Unit Cost = $103/ton

Excavation $83,000

Soil Import, Backfill, & Compaction $54,000

Waste Disposal ($72/ton as non-RCRA) $314,000

TOTAL: $451,000

Economic Analysis = saved $380,000

EHCTMGranular EHCTMPellet EHCTMSlurry EHCTM Powder

EHC is a solid iron/carbon composite material that provides:

• Controlled-release, hydrophilic carbon source

• Micro-scale (5 - 150 µm) zero valent iron (ZVI) or

other reduced metals (Zn, Al), at 5 to 50% weight

• Major, minor, and micronutrients

What is EHC®

Source Area/

Hotspot Treatment

Injection PRB for

Plume Control Plume

Treatment

Dosing: 0.15 to 1% wt/wt

Spacing: 5 to 15 ft (DPT)

Dosing: 0.4 to 1% wt/wt

Spacing: 5 to 10 ft (DPT)

Dosing: 0.05 to 0.2% wt/wt

Line Spacing: based on 1 year

g.w. travel distance

Application Strategies

trenching (50 ft, 15m)

DPT (>250 ft, 75 m)

soil mixing (40 ft, 12 m)

jetting (60 ft, 18 m)

pneumatic fracturing (90 ft, 27 m)

Nitrogen

Gas Source

Overburden

Treatment ZoneIn j ec t o r

Atomized Slurry

in Gas Stream

Packer

Pneumatic

Injection Module

Ferox Injection

Trailer

Common Construction Methods (Depths Achieved to Date)

EHC® Slurry (water content can be varied)

35% solids 30% solids

25% solids 59-01-EIT-DL

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!

59-01-EIT-DL

EHC® ISCR Installation Methods

Direct Injection & ChemGrout Mixing

ChemGrouts CG-500 used for mixing and injections (rated at 20 GPM at 1,000 psi).

59-01-EIT-DL

Direct Push Technologies

EHC Influenced Reductive Treatment

Zone

2 1 3 4

Direct ZVI corrosion effects

Indirect ZVI effects (H2 gas and iron corrosion product generation)

Carbon substrate fermentation produces volatile fatty acids (VFAs),

sulfate released from EHC-M

Biostimulation of the aquifer zone by the dissolved components

1

2

3

4

Fracture Emplacement of a Micro-

Iron/Carbon Amendment for TCE

reduction in a Bedrock Aquifer

FRAC RITE ENVIRONMENTAL LTD.

Fracturing and Emplacement of EHC-G

• 7 Boreholes in “Source Area” Plume (0.27% EHC-G by wt)

• 2 Boreholes in “Dissolved Area” Plume (0.10% EHC-G by wt)

• Fracture-emplacement of “EHC-G” Zero Valent Iron/Carbon by Adventus in zone from 35 ft to 63 ft bgs in bedrock

• Total of 206,000 lb of EHC-G zero valent iron delivered at 42 individual fracture depths – generally 4 to 5 fracs per Borehole.


Atlas 12 Pilot Test

EHC-G Distribution

Source Area:

7 Fracture Boreholes

Dissolved Phase Plume:

2 Fracture Boreholes

EHC-G Injections:

April 20 to May 19, 2009

24,000 lbs;

4 depths

Mass of EHC-G per Borehole;

Number of Fracture Depths 24,000 lbs;

4 depths

32,000 lbs;

5 depths

32,000 lbs;

6 depths

32,000 lbs;

5 depths 24,000 lbs;

4 depths

24,000 lbs;

6 depths

5,700 lbs;

4 depths

8,200 lbs;

4 depths


Fracture Mapping Conducted for 7 boreholes in source area


B

B’

B B’

Fracture Mapping From MW-22 looking west


North-South extent of continuous ZVI/C

coverage is approximately 450 ft, effectively

comprising a treatment barrier

ZVI/C Fracture Characteristics

• Fracture Trend: 60% SSE; 40% NNE

• Average Vertical Dimension = 79 ft.

• Average Lateral Dimension = 65 ft.

• Median Fracture Thickness = 0.3 in.

• Average Aspect Ratio = 1.21

• Maximum Fracture Radius = 80.1 ft.

• Approximate Fracture Overlap = 25%


TCE Treatment Performance (9 months)

Source Area:

Pre-treatment TCE levels -

>2000 to 4,000 ug/L

After 9 months – less than

400 ug/L except at 2 wells

Dissolved Plume Area:

Pre-treatment TCE levels -

500 to 700 ug/L

•After 9 months –

•200 to 400 ug/L


EHC PRB Case Study

• 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 was installed as a line

of injection points spaced

approximately 10 ft / 3 m apart.

• The PRB extended across the

width of the plume and

measures ca 270 ft / 90 m long.

• CT max. 2,700 ppb

• RAO CT< 5 ppb; CF <100;

DCM < 5; CM < 20

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


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


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


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


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


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


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


N

Property Line

0 300 600

SCALE IN FEET

March 2005

EHC® PRB - Plume Treatment Results

59-01-EIT-DL

47 <1

<1

770 140

1000 11 <1

140

490 67

280

460 6.4

37 98

<1

EHC Treatment Zone

Monitoring well and

CT concentration (ug/L)

N

Property Line

0 300 600

SCALE IN FEET

March 2005

After Before 44

<1

<1

1200 67

25 <1 <1

19

15 75

16

72 <1

5.8 25

<1

EHC Treatment Zone

Monitoring well and

CT concentration (ug/L)

N

Property Line

0 300 600

SCALE IN FEET

May 2010

After

EHC® PRB: Plume Treatment Injection

Layout

http://umbbd.ahc.umn.edu

http://umbbd.ahc.umn.edu/ctc/ctc_map

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 < $100,000

$37/ft2 ($395/m2) of PRB cross-section.

• The installation was completed in 12

days using direct injection.

• As of 2010, 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).

59-01-EIT-DL

Approach Bio-based Alternative

Fuel Renewable

Energy Recycled Content

Impact on Soil Quality

EHC and DARAMEND

ISCR Reagents

Excavation and disposal

Sustainability Evaluation

Complementary

Site Evaluations

http://environmental.fmc.com/contact-us/

http://environmental.fmc.com/





Thank you

For more information please contact:

FMC Environmental Solutions 2871 W. Forest Road, Suite 2 Freeport, IL 61032 USA

Ph: (815) 235-3503

[email protected]

Or visit our website: www.environmental.fmc.com

mailto:[email protected]

welcome to the science of iscr webinar · 2014. 2. 20. · origins of “iscr” tratnyek, johnson,...

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