Remediation Technology Symposium (RemTech) 2012 · PDF fileAcknowledgements AFCEE Tech...
Transcript of Remediation Technology Symposium (RemTech) 2012 · PDF fileAcknowledgements AFCEE Tech...
Comparison of Approaches to Engineered In Situ Biogeochemical Transformation of Chlorinated Solvents
19 October 2012
Remediation Technology Symposium (RemTech) 2012
Bruce M. Henry, PG
Acknowledgements
AFCEE Tech Transfer – Dr. Seb Gillette Air Force Demonstration Hosts Joint Base Pearl Harbor-Hickam (JBPHH), Hawaii –
Bill Grannis Altus Air Force Base (AFB), Oklahoma – Dan Stanton Joint Base Elmendorf-Richardson (JBER), Alaska –
Donna Baumler Little Mountain Test Annex (LMTA), Hill AFB, Utah –
Kyle Gorder
Parsons – John Hicks, John Hall, Mitch Jensen
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Presentation Topics
Technical Approaches Engineered Systems – Case Studies Materials Bioreactors Direct Injection
Factors Impacting Performance Amendment Properties and Distribution Utilization of Iron, Sulfate, and Organics Design Considerations – Special Considerations
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Engineered In Situ Biogeochemical Transformation
Chlorinated compounds degraded by abiotic reactions with naturally occurring or biogenically-formed reactive minerals
Abiotic processes typically do not produce intermediate dechlorination products
Alternative or complement to biostimulation using selective Dehalococcoides species
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Framboidal Pyrite
Demonstrate an in situ technology capable of sustained degradation of
chlorinated solvents without accumulation of cis-DCE or VC
AFCEE Objective
Three General Approaches
Production of reactive iron monosulfide (FeS) minerals while limiting biological activity – “one and done” approach (Dover AFB injection; Kennedy et al., 2006)
Continual production of FeS with high sulfate consumption rate (Altus AFB biowalls and bioreactors; Lebron et al., 2010)
Synergistic approach stimulating both production of reactive FeS minerals and biotic dechlorination with bioaugmentation (JBPHH bioreactor study; Leigh et al., 2011)
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Engineered Systems – Case Studies
Materials Iron Amendments Sulfate Amendments
Bioreactors LF05 Bioreactor, JBPHH, HI LF03 Bioreactor, Altus AFB, OK
Direct Injection DP98, JBER, AK North Disposal Area,
LMTA, Hill AFB, UT
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Sulfate amendments are soluble (up to 26,000 mg/L) and migrate with groundwater flow, but dissolution rate may vary (anhydrous versus hydrated forms)
Potential Sulfate Amendments
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Material (most common form)
Percent Sulfate
Percent Iron
Notes
Ferrous Sulfate (heptahydrate) - FeSO4 • 7H2O
35% 20% Soluble
Magnesium Sulfate (heptahydrate) - MgSO4 • 7H20
39% 0% Soluble - Epsom Salt
Calcium Sulfate (dihydrate) - CaSO4 • 2H20
56% 0% Moderate Solubility - Gypsum
Sodium Sulfate (decahydrate) - Na2SO4 • 10H20
30% 0%
Highly Soluble
Percent by weight in hydrated form
Ferrous Sulfate (FeSO4•7H2O)
Solid iron amendments have a broad range of bioavailability
– ranging from 250 to 25,000 mg/kg
Potential Iron Amendments
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Material (most common form)
Percent Sulfate
Percent Iron
Notes
Crushed or Powdered Hematite - Fe2O3
0% 68% Natural or Synthetic (pigment)
Crushed or Powdered Magnetite – Fe3O4
0%
67% Natural or Synthetic (pigment)
Ferrous Chloride (anhydrous) - FeCl2
0% 34% Soluble (corrosive - low pH)
Ferrous Lactate - Fe(C3H5O3)2
0% 28% Soluble – Food Additive
Ferrous Sulfate (heptahydrate) - FeSO4 • 7H2O
35% 20% Soluble
Powdered Hematite (Fe2O3)
LF05 DNAPL Source Bioreactor, JBPHH
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High Iron Native Basalt Sand
Plan View of Hickam LF05 Bioreactor
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Groundwater Flow
Data Shown
Recirculation
1
10
100
1000
10000
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
450,000
-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Tota
l Mo
lar
Ch
lori
nat
ed E
then
es (
mm
ol/L
)
Co
nce
ntr
atio
n (
µg/L
)
Months Since Installation
PCE TCE
Total DCE VC
Ethene + Ethane Total Molar Chloroethenes
Chlorinated Ethenes at Well MW-18
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96% reduction in total molar concentration of chloroethenes
1
10
100
1000
10000
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
-1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Tota
l Mo
lar
Ch
lori
nat
ed E
then
es (
mm
ol/L
)
Co
nce
ntr
atio
n (
µg/L
)
Months Since Installation
PCE TCE
Total DCE VC
Ethene + Ethane Total Molar Chloroethenes
Chlorinated Ethenes at Well MW-38
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95% reduction in total molar concentration of chloroethenes
Contrast to MW-04 for a Prior Bioremediation Pilot
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0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
100,000C
on
cen
trat
ion
(µg
/L)
Date
TCE
cis-1,2-DCE
VC
Persistent cis-1,2-DCE, accumulation of VC
LF-03 Recirculating Bioreactor, Altus AFB, OK
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Solar-powered recirculating bioreactor – built in November 2003
Emulsified vegetable oil (EVO) and ferrous sulfate injected in May-June 2010
LF-03 Injection – EVO + Ferrous Sulfate
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Ferrous Sulfate Product
Direct Injection into Bioreactor Frozen Mulch Sample
Mixed w/ GW + AquaBufpH™
Cumulative and Average Daily Flow
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Sulfate Loading/Consumption Rate Over Time
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0
4,000
8,000
12,000
16,000
20,000
24,000
28,000
32,000
0
100
200
300
400
500
600
700
800
Nov-03 Nov-04 Nov-05 Nov-06 Nov-07 Nov-08 Nov-09 Nov-10 Nov-11
Flo
w R
ate
(L/d
ay)
Su
lfate
Rat
e (m
g/L
/day
)
Date
Sulfate Loading Rate
Sulfate Consumption Rate
Flow Rate
October 2006 Enhancement
May 2010Enhancement
Sulfate consumption up to 200 mg/L/day
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Molar Concentrations of CAHs Over Time at SW3
0
500
1,000
1,500
2,000
2,500
3,000
Baseline 4 Months 7 Months 11 Months
Co
nc
en
tra
tio
n (n
mo
l/L)
Months After EVO/Ferrous Sulfate Injection
TCE
DCE
VC
Ethene
Total CAHs
Transition to biotic degradation due to iron depletion
Abiotic degradation signature
Molar Concentrations of Chloroethenes and Ethene in Deeper Zone Beneath Bioreactor
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0
30,000
60,000
90,000
120,000
150,000
180,000
Baseline 4 Months 7 Months 11 Months
Co
nce
ntr
atio
n (n
mo
l/L)
Months After EVO/Ferrous Sulfate Injection
TCE
DCE
VC
Ethene
Total CAHs
Reduction in TCE without accumulation of DCE or VC
Cumulative Mass Removal
0
5
10
15
20
25
30
35
40
45
50
May
-03
May
-04
May
-05
May
-06
May
-07
May
-08
May
-09
May
-10
May
-11T
ota
l CA
H M
ass
Rem
ova
l (kg
)
Date
May 2010 Enhancement
October 2006 Enhancement
Note: Bioreactor was down for an unknown period prior to repair in January 2010.
Mass removal = 0.042 kg/day
Mass removal = 0.015 kg/day
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Influent versus Bioreactor Concentrations
Compound Influent (May 2010)
Within Bioreactor (May 2010)
Within Bioreactor (May 2011)
Percent Reduction (May 2010)
Percent Reduction (May 2011)
TCE (µg/L) 3,600 183 2.6 95% 99.7%
cis-DCE (µg/L) 2,300 725 169 69% 91%
VC (µg/L) 80 50 174 38% +2.3%
Ethene (µg/L) 9 3.3 29 Decrease Increase
Total Molar Chloroethenes (nmol/L)
52,900 9,890 4,800 81% 85%
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May 2010 and May 2011 (1 mo. pre- and 11 mo. post-injection)
Dechlorination efficiency for TCE, DCE, and Total Molar Chloroethenes improved after injection
Case Study: DP98, JBER, Alaska
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Direct-Push Injection Test Cell No. 1 (May 2010)
DP98 Test Cell Scenarios
Site/Location Amendments
Notes
Test Cell No. 1 EHC® Control Tight silty clay with silty sand layers, low to moderate GW flow
Test Cell No. 2 Gypsum, Hematite, Emulsified Vegetable Oil (EVO)
Tight silty clay with silty sand layers, low to moderate GW flow
Test Cell No. 3 Ferrous Sulfate with EVO Injected in former bioremediation pilot test
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A buffered EVO product was used to stabilize pH
Chloroethenes at Test Cell No. 2 (EVO + Hematite + Gypsum)
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215134
7
3
3,531 3,3212,048
1,394
1.9
1114 20
7.9
1.7
3.2
1.00
5,000
10,000
15,000
20,000
25,000
30,000
35,000
40,000
1
10
100
1,000
10,000
100,000
0 2 4 6 8 10 12 14 16
To
tal l
Mo
lar
CA
Hs
(n
mo
l/L
)
Co
nc
en
tra
tio
n (µ
g/L
)
Months Since Installation
TCE Total DCE VC Ethene + Ethane Total Molar
61% decrease in Total DCEand Total Molar CAHs
Stable VCTCE reduced to below MCL
Contrast with 2005 Biostimulation with EVO
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4,920 1,980
ND ND
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6,366 4,696 11,147 7,838
11,068
ND ND
74
ND
200
1.2 1.2 1.7 1.4
1
10
100
1,000
10,000
100,000
0 6 12 18 24 30 36
Co
nce
ntr
atio
n (µg
/L)
Months Since Injection
CONCENTRATIONS OF CHLOROETHENES AT INJECTION LOCATION DP98INJ-02
TCE Total DCE VC Ethene + Ethane
Biostimulation stalls at cis-DCE
North Disposal Area, LMTA, Utah
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TCE Plume in 2007
LMTA Performance Objectives
Generate FeS up to 1,000 to 3,000 mg/kg Enhance rates of degradation by an order of magnitude
or more over natural rates Reduce total molar concentrations by over 90 percent (no
increase in cis-1,2-DCE or VC)
Soil cores before injection, LMTA, Utah
Soil cores 6 months after injection, LMTA, Utah
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Ferrous Iron, Sulfate, and Sulfide at LM-679 in Test Cell No. 1 (Ferrous Sulfate + EVO)
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ND
14.2
19.5
4.900.80
0.741.14
7.86
38.9
236
556
461
212 219
0
100
200
300
400
500
600
0
10
20
30
40
50
60
-1 0 1 2 3 4 5 6 7 8 9 10 11 12
Sul
fate
Con
cent
ratio
n (m
g/L)
Con
cent
ratio
n (m
g/L)
Months from InjectionFerrous Iron Sulfide Sulfate (secondary axis)
Build up of sulfide indicates iron is limiting factor
Ferrous Iron, Sulfate, and Sulfide at LM-683 in Test Cell No. 2 (Powder Hematite + Mg Sulfate)
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0.11 0.69
21.0
17.5
2.94
0.70
3.47ND
4.57118
1,348
52 13.3ND 0
300
600
900
1200
1500
0
10
20
30
40
50
-1 0 1 2 3 4 5 6 7 8 9 10 11 12
Sul
fate
Con
cent
ratio
n (m
g/L)
Con
cent
ratio
n (m
g/L)
Months from InjectionFerrous Iron Sulfide Sulfate (secondary axis)
Low sulfate is limiting factor
Sulfate utilized at a faster rate than iron
Chloroethenes at Test Cell No. 1 (Ferrous Sulfate w/ EVO)
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Dissolved Organic Carbon in NDA Test Cells
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0
100
200
300
400
500
-1 0 1 2 3 4 5 6 7 8 9 10 11 12
Con
cent
ratio
n (m
g/L)
Months from Injection
LM-679
LM-680
LM-683
LM-684
Excess of Substrate
Factors Impacting Performance
High sulfate consumption rate is desirable Substrate type should behave like amendment type
(soluble with soluble and solids with solids) Utilization rates – in general soluble sulfate
reduction will be greater than solid phase iron reduction
Mineral saturation/super saturation states for iron sulfide minerals (geochemical modeling)
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Slow release substrates such as EVO are not a good fit with soluble amendments
Factors Impacting Performance (continued)
Adequate groundwater mixing – nucleation versus crystal growth
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Pyrite Framboids with high surface area Large pyrite grain with low surface area
Design Considerations
Limit substrate to avoid over stimulation of biological processes, yet provide for continual production of fresh FeS minerals
Use conservative tracers to confirm utilization of soluble sulfate and ferrous iron amendments
Configurations suitable for multiple injections or recirculation allow the greatest potential for optimizing the ratio of organic substrate to sulfate to iron
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Given the challenges to enhancing abiotic processes without significant biotic dechlorination, a synergistic approach optimizing biogeochemical processes along with bioaugmentation may be an optimal approach.
Optimal Approach
Special Considerations
Co-contaminants such as nitrate and heavy metals Low pH, poor buffering capacity Very high or very low rates of groundwater flow Overstimulation of biotic dechlorination Sites with high initial populations of dechlorinators (sites
with high concentrations of DCE, VC, or DCA)
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Buffering products for pH control
Bioaugmentation for sites with DCE, VC, or DCA
Mitigation Measures
References
AFCEE. 2008. Technical Protocol for Enhanced Anaerobic Bioremediation Using Permeable Mulch Biowalls and Bioreactors. Prepared by Parsons, Denver, Colorado.
Lebrón, C., P. Evans, K. Whiting, J. Wilson, E. Becvar, and B. Henry. 2010. In situ Biogeochemical Transformation of Chlorinated Ethenes Using Engineered Treatment Systems. Prepared for NAVFAC ESC and ESTCP.
Kennedy, L., J.W. Everett, E. Becvar, and D. DeFeo. 2006. Field-scale demonstration of induced biogeochemical reductive dechlorination at Dover Air Force Base, Dover, Delaware. Journal of Contaminant Hydrology, Vol. 88:119-136.
Leigh, D.P., R.J. Steffan, W. Grannis, and E. Becvar. 2011. Biogeochemical Degradation of Chlorinated Ethenes at Hickam AFB, Hawaii, Using Sustainable Processes. Presentation C-01, 2011 Battelle Symposium, Reno, NV.
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Questions and Discussion
Comparison of Approaches to Engineered In Situ Biogeochemical Transformation of Chlorinated Solvents Bruce M. Henry, PG 19 October 2012