nZVI Field Application Case nZVI Field Application Case Studies in the U.S.Studies in the U.S.

Daniel W. Elliott, Ph.D.Daniel W. Elliott, Ph.D.

Geosyntec Consultants, UNC-Chapel HillGeosyntec Consultants, UNC-Chapel Hill

Field-Scale Iron Nanoparticle Remediation Field-Scale Iron Nanoparticle Remediation Experience and Evolving Risk Benefit Experience and Evolving Risk Benefit

UnderstandingUnderstanding

USEPA CLU-IN WebinarUSEPA CLU-IN Webinar

14 December 201014 December 2010

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OutlineOutline

i.i. Introduction to field-scale use of nZVIIntroduction to field-scale use of nZVI

ii.ii. Overview of the case studyOverview of the case study

iii.iii. A decade of nZVI injections in NJA decade of nZVI injections in NJ

iv.iv. Field-scale implications and issuesField-scale implications and issues

v.v. Final thoughtsFinal thoughts

i. nZVI from lab to fieldi. nZVI from lab to field Significant experience with demonstrating that the Significant experience with demonstrating that the

chemistry workschemistry works Amenable reductates: CAHs, oxidized MeAmenable reductates: CAHs, oxidized Mex+x+, pesticides, , pesticides,

Cl & NOCl & NO22-aromatics, ClO-aromatics, ClO44--, etc., etc.

Lab success may not follow in field Lab success may not follow in field Batch study complexity << field conditionsBatch study complexity << field conditions Mixing differences and contact Mixing differences and contact

Scaling-up and benchmarking difficultScaling-up and benchmarking difficult Variability in site conditions and nZVIVariability in site conditions and nZVI Very costly to rigorously assess performanceVery costly to rigorously assess performance

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i. Drivers for nZVI in remediationi. Drivers for nZVI in remediation Multiple delivery options/broad efficacy:Multiple delivery options/broad efficacy:

Injection of nZVI slurries through MW and DPT Injection of nZVI slurries through MW and DPT technologytechnology

Diffuse CAH plumes in GW & DNAPL zonesDiffuse CAH plumes in GW & DNAPL zones Immobilization of redox-sensitive metalsImmobilization of redox-sensitive metals

Technology synergies:Technology synergies: Profound water chemistry impactsProfound water chemistry impacts

FeFe00 + 2H+ 2H22O O Fe Fe2+2+ + + HH22 +2OH +2OH--

Anaerobic biodegradation and nZVIAnaerobic biodegradation and nZVI

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i. Profound water chemistry impactsi. Profound water chemistry impacts

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0 90 180 270 360 450 540 630 720

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0.10 g/L nZVI in DI H2O

i. Perspectives on nZVIi. Perspectives on nZVI

Rapid evolution of technologyRapid evolution of technology• Developed at Lehigh in 1996Developed at Lehigh in 1996• 11stst field deployment in 2000 field deployment in 2000• Burgeoning interest in Burgeoning interest in

academia, industry, regulatorsacademia, industry, regulators

AttributesAttributes• Enhanced reactivityEnhanced reactivity• Target hot-spot areas & tough Target hot-spot areas & tough

reductatesreductates

nZVI vendor developmentsnZVI vendor developments• 2000 = None2000 = None• 2010 = Many, worldwide2010 = Many, worldwide• Various manufacturing Various manufacturing

methodsmethods

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i. Variety of iron nanoparticlesi. Variety of iron nanoparticles

Bare nZVIBare nZVI Bimetallics (Fe/Pd, etc.)Bimetallics (Fe/Pd, etc.) Supported nZVI Supported nZVI

Carbon or polymeric bead substrateCarbon or polymeric bead substrate Emulsified ZVI (eZVI) Emulsified ZVI (eZVI)

nZVI or mZVI within emulsified oil micellesnZVI or mZVI within emulsified oil micelles Surface-modified nZVISurface-modified nZVI

Surfactant/polymer-based surface architecturesSurfactant/polymer-based surface architectures

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ii. Case study site overviewii. Case study site overview

Manufacturing site in Trenton, NJ Manufacturing site in Trenton, NJ Active since 1937Active since 1937 Springs, appliances, HVAC equipmentSprings, appliances, HVAC equipment

RI began 1990RI began 1990 Multiple interim remedial measuresMultiple interim remedial measures

Soils and groundwater impactSoils and groundwater impact Well-characterized TCE plumeWell-characterized TCE plume Ongoing reductive dechlorination Ongoing reductive dechlorination

NJDEP case team very involvedNJDEP case team very involved Meetings, submittal of benchscale study & nZVI data, Meetings, submittal of benchscale study & nZVI data,

permit-by-rule for injection permit-by-rule for injection

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ii. Objectivesii. Objectives

Field efficacyField efficacy Works in the lab but…Works in the lab but… Degradation products?Degradation products? Mobility in the subsurface?Mobility in the subsurface?

Enhance ongoing NA processes Enhance ongoing NA processes Lower TCE & ELower TCE & EHH, Increase Fe, Increase Fe2+,3+2+,3+

Drive anaerobic biodegradation processesDrive anaerobic biodegradation processes Role of nZVI in site remediation strategyRole of nZVI in site remediation strategy

Evaluation of different injection techniquesEvaluation of different injection techniques Cost-effectivenessCost-effectiveness

iii. Overview of treatment areasiii. Overview of treatment areas

Two key areas of site: Two key areas of site: DGC-15 & AOC-3DGC-15 & AOC-3

DGC-15:DGC-15: Downgrad of bldg & mfg areas, NW cornerDowngrad of bldg & mfg areas, NW corner DGC-12, DGC-15, MW-18DGC-12, DGC-15, MW-18

AOC-3:AOC-3: Former 5,000-gal TCE AST, upgrad of bldgFormer 5,000-gal TCE AST, upgrad of bldg DGC-9, DGC-9D, MW-28DGC-9, DGC-9D, MW-28

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iii. Aerial view of site – Trenton, NJiii. Aerial view of site – Trenton, NJ

DGC-15 AOC-3

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iii. Three nZVI injection campaignsiii. Three nZVI injection campaigns

June-Aug 2000June-Aug 2000 11stst field demonstration of technology field demonstration of technology Small-scale injections, proof-of-conceptSmall-scale injections, proof-of-concept

June-Nov 2003June-Nov 2003 Utilization of supported nZVIUtilization of supported nZVI Demonstrated efficacy of larger-scale injectionDemonstrated efficacy of larger-scale injection

May-Dec 2007May-Dec 2007 Surface-modified nZVISurface-modified nZVI Large-scale injection (500 lbs) under buildingLarge-scale injection (500 lbs) under building

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iii. Pre-injection conditionsiii. Pre-injection conditions

Key contaminants: TCE & daughtersKey contaminants: TCE & daughters Surficial aquifer impactedSurficial aquifer impacted

Silty sands & clays, saprolite above bedrock (35 ft bgs)Silty sands & clays, saprolite above bedrock (35 ft bgs)

Key hydrogeological parameters:Key hydrogeological parameters: K ~10K ~10-2-2 m/s, i ~0.01, v ~0.3-3 m/d m/s, i ~0.01, v ~0.3-3 m/d

Field parameters (DGC-15, AOC-3):Field parameters (DGC-15, AOC-3): D.O. ~0-2 mg/L; ORP ~+200 mV; pH ~4.5-5.5D.O. ~0-2 mg/L; ORP ~+200 mV; pH ~4.5-5.5

Chloroethenes (DGC-15, Chloroethenes (DGC-15, AOC-3AOC-3):): TCE ~400-600 TCE ~400-600 g/L; c-DCE ~200 g/L; c-DCE ~200 g/L; VC ~10 g/L; VC ~10 g/Lg/L TCE ~200-300 TCE ~200-300 g/L; c-DCE ~50 g/L; c-DCE ~50 g/L; VC ~1-10 g/L; VC ~1-10 g/Lg/L

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iii. DGC-15 area schematic (2000, 2003) iii. DGC-15 area schematic (2000, 2003)

1.5 m 1.5 m 1.5 m

4.8 – 6.0 m

2.4 – 3.6 mGroundwater

DGC-15PZ-1 PZ-2 PZ-3

FlowmeterNanoparticle Suspension (400 L)

3.0 – 4.5 mRecirculation systemRecirculation system

Gravity feed injection Gravity feed injection (~1g/L) nZVI slurry(~1g/L) nZVI slurry

Within plume, downgradient Within plume, downgradient of manufacturing buildingof manufacturing building

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iv. nZVI injection underway (2000)iv. nZVI injection underway (2000)

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2000 - Phase I TCE Reduction, %

Day 2-3Day 9Day 23

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iii. 2007 Geoprobe injection strategyiii. 2007 Geoprobe injection strategy Two approaches:Two approaches:

(1) Wells INJ-1 & INJ-2 & (2) DPT (Geoprobe) (1) Wells INJ-1 & INJ-2 & (2) DPT (Geoprobe)

Geoprobe 6610 used to inject 300 lbs iron Geoprobe 6610 used to inject 300 lbs iron Sodium polymethacrylate (NaSodium polymethacrylate (Na++PMA) stabilizedPMA) stabilized 2-150 gal poly tanks containing ~20 g/L nZVI slurry2-150 gal poly tanks containing ~20 g/L nZVI slurry Formation water from INJ-1 used to dilute nZVIFormation water from INJ-1 used to dilute nZVI

DPT injection strategyDPT injection strategy 2 transects of borings2 transects of borings 3 depth intervals: 8-12, 14-16, 23-25 ft bgs3 depth intervals: 8-12, 14-16, 23-25 ft bgs Approx 20-25 lbs nZVI per boring, some “double-shots”Approx 20-25 lbs nZVI per boring, some “double-shots” 8-12 ft depth interval very low permeability8-12 ft depth interval very low permeability

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iii. Infrastructure for Geoprobe injectioniii. Infrastructure for Geoprobe injection

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iii. 2007 nZVI injection results iii. 2007 nZVI injection results Within Area 3, significant redox chemistry Within Area 3, significant redox chemistry

ORP: ~ +200 mV to -300 mVORP: ~ +200 mV to -300 mV pH: ~0.5 to 1 std unit increasepH: ~0.5 to 1 std unit increase

Boring B-7 (middle of test area)Boring B-7 (middle of test area)

nZVI reducing TCE, 2nZVI reducing TCE, 200 bio more important? bio more important? Effects of surface-modificationEffects of surface-modification

nZVI traveled >30 ft, evident in cores beneath bldgnZVI traveled >30 ft, evident in cores beneath bldg Potentially some loss of reactivity, too much NaPotentially some loss of reactivity, too much Na++PMA?PMA?

InjectionInjection TCE (TCE (g/L)g/L) c-DCE (c-DCE (g/L)g/L) t-DCE (t-DCE (g/L)g/L)

PrePre 220220 4545 NDND

Post (6 months)Post (6 months) 145145 1010 1010

iii. Longer-term look at DGC-15 & AOC-3iii. Longer-term look at DGC-15 & AOC-3 2010 data (basis 2000)2010 data (basis 2000)

Difficult to interpret resultsDifficult to interpret results Contaminant trends are decreasingContaminant trends are decreasing Overlapping attenuation mechanismsOverlapping attenuation mechanisms Activity of iron? Activity of iron?

2020

TCE % Red c-DCE % Red VC % Red

DGC-15 220 45-60 170 15 15 -50

AOC-3 100 55 30 33<1

(ND)0

iv. Implications and Issuesiv. Implications and Issues

Multiple injections will be requiredMultiple injections will be required Dosing and frequencyDosing and frequency Cost to implement nZVI not well definedCost to implement nZVI not well defined

Lack of QA/QC data for ironLack of QA/QC data for iron H&S exposure issuesH&S exposure issues

PPE = Gloves, safety glasses PPE = Gloves, safety glasses Regulatory acceptance Regulatory acceptance

NJDEP on board with nZVI application at siteNJDEP on board with nZVI application at site Fate and transport of the injected nZVIFate and transport of the injected nZVI

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iv. nZV QA/QC – major data gapsiv. nZV QA/QC – major data gaps

Documentation provided = MSDSDocumentation provided = MSDS Info focuses on safety not efficacyInfo focuses on safety not efficacy

How do you know if the nZVI is still active?How do you know if the nZVI is still active? Minimal product lifecycle analysesMinimal product lifecycle analyses Variable mfg methods and storage periodsVariable mfg methods and storage periods

What performance or quality data is What performance or quality data is needed from vendor?needed from vendor?

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iv. Potential QA/QC parametersiv. Potential QA/QC parameters

““Born on date” & storage methodBorn on date” & storage method pH/ORP profilepH/ORP profile Particle size distribution (PSD)Particle size distribution (PSD) Specific surface area (SSA)Specific surface area (SSA) Zeta potential (Zeta potential () & Isoelectric point (IEP)) & Isoelectric point (IEP) Batch reactivity testBatch reactivity test

QA/QC should be low cost, rapid, and easy to develop QA/QC should be low cost, rapid, and easy to develop

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iv. Environmental fate considerationsiv. Environmental fate considerations

Rapid aggregation of nZVIRapid aggregation of nZVI Core-shell structure Core-shell structure FeFe00 core shrinks over time, core shrinks over time,

oxide shell growsoxide shell grows Magnetite (FeMagnetite (Fe33OO44) rich oxides ) rich oxides

Fe in +2.67 ox. state Fe in +2.67 ox. state Maghemite (FeMaghemite (Fe22OO33) rich oxides ) rich oxides

Fe in +3 ox. stateFe in +3 ox. state

Iron oxides removed by aquifer Iron oxides removed by aquifer mediamedia

Activity 0.5-1 yr or longer?Activity 0.5-1 yr or longer?

Fe00

Fe oxides

ee-- transfer across oxide shell transfer across oxide shell

v. Major considerationsv. Major considerations

Performance vs. costPerformance vs. cost Typically 5-20 g/L but how many rounds? Frequency?Typically 5-20 g/L but how many rounds? Frequency? Effect of non-target reductates (water, e-acceptors, etc.) when Effect of non-target reductates (water, e-acceptors, etc.) when

treating relatively dilute contaminant plumestreating relatively dilute contaminant plumes ~$30/lb vs. ~$1-10/lb for mZVI~$30/lb vs. ~$1-10/lb for mZVI

Delivery issuesDelivery issues Reasonable hydrogeologyReasonable hydrogeology Injection well(s), recirc. loops, transects of boringsInjection well(s), recirc. loops, transects of borings

Interpretation of post-injection dataInterpretation of post-injection data Complicated & overlapping attenuation mechanismsComplicated & overlapping attenuation mechanisms

Proximity of receptorsProximity of receptors Exposure issues: VI, off-site considerations, GW discharge areasExposure issues: VI, off-site considerations, GW discharge areas

Amenability of regulatorsAmenability of regulators

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v. Final thoughtsv. Final thoughts

nZVI a useful complementary remedial nZVI a useful complementary remedial technologytechnology

Major hurdle limiting growth is lack of robust Major hurdle limiting growth is lack of robust cost-effectiveness datacost-effectiveness data

Environmental fate of nZVI likely a lesser Environmental fate of nZVI likely a lesser concern in comparison to worker exposureconcern in comparison to worker exposure

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Thanks! Any questions?Thanks! Any questions?

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