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A Six-Year Field Test of Emulsified Zero-Valent Iron to Treat Source - - PowerPoint PPT Presentation

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A Six-Year Field Test of Emulsified Zero-Valent Iron to Treat Source Zone Chlorinated Solvents at a Superfund Site November 2, 2015 Chunming Su, EPA Robert Puls, EPA (retired) Tom Krug, GeoSyntec Mark Watling, GeoSyntec Suzanne OHara,

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Office of Research and Development National Risk Management Research Laboratory Ground Water and Ecosystems Restoration Division, Ada, OK

A Six-Year Field Test of Emulsified Zero-Valent Iron to Treat Source Zone Chlorinated Solvents at a Superfund Site

Chunming Su, EPA Robert Puls, EPA (retired) Tom Krug, GeoSyntec Mark Watling, GeoSyntec Suzanne O’Hara, GeoSyntec Jacqueline Quinn, NASA Nancy Ruiz, US Navy

November 2, 2015

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Properties of Emulsified Zero-Valent Iron (EZVI)

  • Emulsion droplets contain nanoscale zero-valent iron (ZVI)

particles in water surrounded by an oil-liquid membrane (food-grade surfactant, biodegradable vegetable oil)

  • Oil layer of emulsion is miscible with the DNAPL
  • Chlorinated volatile organic compounds (CVOCs) diffuse

through the oil membrane and are degraded in the presence

  • f the ZVI in the interior aqueous phase
  • EZVI can be used to enhance degradation of DNAPL by

enhancing contact between the DNAPL and the ZVI particles

  • Due to vegetable oil and surfactant which will act as long-

term electron donors, EZVI also promotes anaerobic biodegradation

Water Oil Surfactant Iron

  • 12. 3 µm

Jacqueline Quinn, NASA

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Objectives

  • To evaluate two injection technologies (pneumatic and

direct injections) within a DNAPL source zone for EZVI delivery

  • To evaluate the effectiveness of EZVI to decrease mass

flux of dissolved volatile organic compounds (VOCs) from a DNAPL source zone and decrease the DNAPL mass in the source area

  • To investigate fate and transport of injected nanoscale ZVI

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Reasons for Selecting Parris Island site:

  • Free phase DNAPL
  • Easy access
  • Site support available
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Demonstration Site

Marine Corps Recruit Depot Parris Island, SC Former dry cleaner facility Buildings torn down Source areas located around former above- and below-ground storage tanks Tetrachloroethene (C2Cl4,PCE) Spill in 1994

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  • 9 soil cores and groundwater samples collected in 2005 and 2006 to evaluate

contaminant distribution

  • Wells installed in June 2006 to target the source areas identified through cores

Previous Storage Tank Area Direct Injection Plot Pneumatic Injection Plot

GW flow rate 0.15 – 0.18 ft/day

1.5 3 1.5 3 Meters Meters

SC-9 SC-2 SC-4 SC-6 SC-8 TW-1 TW-4 TW-3 SC-7 SC-5 SC-3 SC-1 TW-2 PMW-1 PMW-2 PMW-4 PMW-3 ML-7 ML-1 ML-2 ML-6 ML-5 ML-4 ML-3 PMW-5 PMW-6

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Pneumatic Injection Plot Targeted VOCs 38 kg Direct Injection Plot Targeted VOCs 155 g

Monitoring Well Installation

Multilevel Well Construction Direct and Pneumatic Injection Plots

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Baseline Characterization

  • Samples collected from over 50 sample

locations (including multilevel wells) during June, August, and October 2006 sampling events

  • Sample parameters include fjeld parameters

(DO, ORP, pH, conductivity, turbidity), CVOCs, DHGs, VFAs, anions, alkalinity, TOC/TIC, metals (dissolved, total), and isotopes (C-13, Cl-37)

  • Integral pump test performed downgradient of

Pneumatic Injection test plot DNAPL

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EZVI Preparation

  • EZVI made on-site by combining:
  • Nanosized iron (Toda, 35-140 nm, $2

lb) 10% by weight

  • Corn oil 38%
  • Surfactant (Sorbitan Trioleate) 1%
  • Tap water 51%
  • Ingredients added to drum and mixed

using a top mounted industrial mixer

  • EZVI pumped from mixing drums into

injection tanks

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Pneumatic Injection Plot Direct Injection Plot

sand silty clay sand peat

0 m 1 m 2 m 4 m 6 m

sand silty sand sand peat sand/clay

3 m 5 m

Fully screened and multilevel wells

Demonstration Site

Target zone: 2-3.5 m bgs Target zone: 2-6 m bgs

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EZVI Injections Pneumatic Injection Plot

  • 575 gal EZVI injected at 8

locations between 7 and 19 ft bgs (2 locations using Direct Injection)

  • During injections, monitored

injection pressure, pressure distribution in subsurface, ground heave, and looked for EZVI at ground surface (daylighting)

1.5 3 Meters

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Direct Injection Plot

  • 150 gal EZVI injected at 4

locations between 6 and 12 ft bgs

  • During injections, monitored

injection pressure and looked for EZVI at ground surface (daylighting)

1.5 Meters

EZVI Injections

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3

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EZVI Injection

EZVI daylighted in both Pneumatic Injection and Direct Injection Plots Pneumatic Injection plot Direct Injection plot (daylighting around ML-3 pad, (daylighting possibly from down-gradient of plot)

  • ld soil core location)

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EZVI Soil Cores

  • Collected cores to evaluate ability of injection

technologies to distribute EZVI evenly over the target treatment intervals

Sand saturated with EZVI

  • EZVI was observed in all soil cores with the

possible exception of ESC-06

  • The most conservative estimate of travel

distance was made by using the closest injection points as the assumed point of

  • rigin.

ESC-04, 12-16ft

1.5 3 Meters

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Performance Monitoring

  • Samples collected from same

locations as baseline sampling events; samples collected in November 2006; January, March, and July 2007; and January, July 2008; March 2009; September, October 2010; October 2012 (2-3 week sampling events)

  • Samples analyzed for the same

parameters as baseline events

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Upgradient Mass Flux Estimates Based on Wells ML-1 and ML-2

Mass Flux (mmol yr-1 m-2) 45,000 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5,000

Pre-Injection (August & October 2006) November 2006 & January 2007 March & July 2007 January & July 2008 Post-Demonstration (March 2009) September 2010 October 2012

PCE TCE cDCE VC Ethene Compound

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Downgradient Mass Flux Estimates Based on Wells ML-3 and ML-7

Mass Flux (mmol yr-1 m-2) 25,000 20,000 15,000 10,000 5,000 PCE

Pre-Injection (August & October 2006) November 2006 & January 2007 March & July 2007 January & July 2008 Post-Demonstration (March 2009) September 2010 October 2012

TCE cDCE VC Ethene Compound

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Pre- and Post-demonstration CVOC Mass Estimates in Pneumatic Injection Plot

Pre-Injection Mass Post-demonstration Media VOC (g) Mass (g) Sorbed/Dissolved DNAPL Total Sorbed/Dissolved DNAPL Total Soil PCE 2,760 29,028 31,788 3,116 1,384 4,500 TCE 1,317 1,317 672 672 Cis-DCE 1,254 1,254 1,542 1,542 VC 2,214 2,214 204 204 Groundwater PCE 577 577 48 48 TCE 267 267 50 50 Cis-DCE 588 588 1,226 1,226 VC 12 12 103 103 Total Mass (g) 8,990 29,028 38,018 6,962 1,384 8,346 % Reduction 23% 95% 78%

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X-ray Diffractograms of Solids from Well Purge Water

Fe0: α-Fe0 M: Magnetite (Fe3O4) L: Lepidocrocite (γ-FEOOH) G: Goethite (α-FeOOH) 25

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X-ray Diffractograms of Soil Cores (2.5 Years After Injection)

Q: Quartz (SiO2) K: Kaolinite (Al2Si2O5(OH)4) P: Pyrite (FeS2) M: Magnetite (Fe3O4) 26

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27 c: ML3-1, 3/3/09 d: ML3-2, 7/7/07 f: ESC-12, 4.6-4.8 m, 3/19/09 e: ML3-2, 3/3/09 b: ML3-1, 7/7/07 a: RNIP-10DS, Aged 8 days

Scanning Electron Microscopy

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Cl Cl C C PCE Cl a 2 a dichloroacetylene C C Cl Cl b 17 d 16 15 d 6 Cl 1 b 3 b Cl Cl TCE C C b 4 H Cl b 5 a: β-elimination b: Hydrogenolysis c: α-elimination d: Hydrogenation Degradation Pathways chloroacetylene C C Cl H b 14 acetylene C C H H 12 C4 compounds a 8 13 d 10 a 7 b trans-1,2-DCE Cl C Cl H C H b 18 b 9 cis-1,2-DCE Cl C H Cl C H ethene H C H H C H vinyl chloride Cl C H H C H 11 c 1,1-DCE Cl C H H C Cl 19 d C2H6 ethane

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Conclusions

  • Injected nanoiron was transformed to iron oxides (with greater

particle size) mostly within three months.

  • EZVI resulted in more reducing conditions that stimulated

dechlorinating bacteria; there is no evidence of adverse effect to the microbial communities.

  • Radius of influence was as much as 2.1 m with pneumatic

injection and 0.89 m with direct injection.

  • There were significant reductions in the downgradient

groundwater mass flux.

  • There were significant reduction in total VOC and DNAPL.
  • EZVI technology can be successfully applied to treat source zone

DNAPL.

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Acknowledgements

  • Mr. Brad Scroggins, Mr. Ken Jewell, Mr. Russell Neil, Mr. Justin Groves,
  • Mr. Mark White, Mr. Pat Clark, Ms. Lynda Callaway, Ms. Kristie Hargrove,

EPA/ORD/NRMRL

  • Professors Christian Clausen, Cherie Geiger, University of Central Florida
  • Ms. Deborah Schnell, Mr. Cornel Plebani, Pneumatic Fracturing, Inc.
  • Mr. Corey Gamwell, Mr. Andrew Thornton, Vironex Environmental Field

Services

  • Mr. Steve Randall, Geosyntec
  • Mr. Steve Markham, Mr. Andrew Greenwood, CB&I
  • Mr. Tim Harrington, Ms. Lisa Donohoe, Marine Corps Recruit Depot, Parris

Island, SC

  • Ms. Bridget Toews, Independent Student Contractor

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Questions?

The Kerr Lab

Ground Water and Ecosystems Restoration Division (Kerr Lab) National Risk Management Research Laboratory Office of Research and Development United States Environmental Protection Agency Ada, Oklahoma

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