Surfactant Flushing
2009 Pilot Study
Fueling Point – Military Site
Northeastern USA
Jeffrey H. Harwell
Asahi Glass Chair of Chemical Engineering
The University of Oklahoma
Principal
Surbec Environmental, LLC
Background
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Jet fuel spill discovered in 2006
Probably happened in 2001
Depth to water 44 ft
Sandy aquifer - 20% silt
Drinking water wells within ¼ mile but in
deeper aquifer
Estimated 350,000 to 700,000 gal spill
Pilot Study Objectives
Surfactant Enhanced Aquifer Remediation (SEAR)
• Evaluate effectiveness and efficiency
• Demonstrate chemical/hydraulic control
• Generate design for full-scale implementation
Pilot Study Location
• Within the LNAPL plume
• generally up-gradient
• minimize recontamination
• No impact to existing soil vapor extraction system
Treatability Study
Surfactant system design
• Provide proof of concept
• Geochemistry considerations
• Heterogeneity issues
• Optimization of injection strategy
•
Step 1: Formulate Microemulsion
I
III
II
Micelle
Monomer
Monomer
Increasing Salinity
Organic
Contaminant
Step 1: Formulate Microemulsion
BA-1
BA-2
BA-3
BA-4
BA-5
BA-6
BA-7
BA-8
BA-9
BA-10
BA-11
Surf. A
(wt%)
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
0.75
Surf. B
(wt%)
0.19
0.19
0.19
0.19
0.19
0.19
0.19
0.19
0.19
0.19
0.19
Salt A
(wt%)
1.5
1.5
1.2
1.3
1.4
1.6
1.7
1.8
1.9
2.0
2.1
Salt B
(wt%)
0.06
0.10
0.10
0.10
0.10
0.10
0.10
0.10
0.10
0.10
0.10
BA-12
0.75
0.19
2.2
0.10
Yes
Clear
BA-13
BA-14
BA-15
BA-16
BA-17
0.75
0.75
0.75
0.75
0.75
0.19
0.19
0.19
0.19
0.19
0.8
1.5
1.6
1.7
2.5
0.10
0.10
0.10
0.10
0.10
No
Yes
Yes
Yes
Yes
Hazy
Clear
Clear
Clear
Clear
Vials
Middle Aqueous
Phase
Phase
No
Hazy
Yes
Clear
Yes
Clear
Yes
Clear
Yes
Clear
Yes
Clear
Yes
Clear
Yes
Clear
Yes
Clear
Yes
Clear
Yes
Clear
NAPL
Phase
Yellow
Yellow
Yellow
Yellow
Yellow
Yellow
Yellow
Yellow
Yellow
Yellow
Yellow
Hazy
Yellow
Yellow
Yellow
Yellow
Yellow
Yellow
Table 1 Microemulsion Phase Behavior
Mixture of food grade anionic surfactants
Winsor
Type
I
III
III
III
III
III
III
III
III
III
III
III
I
III
III
III
III
Step 2: Verify Adsorption Losses are Reasonable
Summary of Sorption Test
Soil:
Water:
i=
f=
Q=
Ci =
Ceq =
V=
M=
Ft. Drum
Ft. Drum sediment - dryed & sieved with #10 (d < 2.0 mm)
DI water
initial
final
(mass sorbed/mass media) = (Ci - Ceq)V / M
Initial Concentration of surfactant
Final Concentration of surfactant
volume of solution
mass of media
Batch
M
V
[Surf A],i [Surf B],i [Total Surf],i [Surf A],f [Surf B],f [Total Surf],f Q, Surf A Q, Surf B Q, Total Surf %, loss of # of surf PV to be applied
Name
g
ml
mg/L
mg/L
mg/L
mg/L
mg/L
mg/L
mg/g
mg/g
mg/g
total surf to compensate for the loss
AD022409-1
0
15
6652.8
2038.4
8691.2
6652.8
2038.4
8691.2
0.0
1.00
AD022409-2
5.0015
15
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
AD022409-3
5.0025
15
6652.8
2038.4
8691.2
6384.0
1980.1
8364.1
0.8
0.2
1.0
3.8
1.04
AD022409-4
5.0011
15
3326.4
1019.2
4345.6
3270.4
984.7
4255.1
0.2
0.1
0.3
2.1
1.02
AD022409-5
5.0032
15
665.3
203.8
869.1
406.6
199.3
605.8
0.8
0.0
0.8
30.3
1.30
Note: The analytical results of surfactant A are in the range of ±10%.
Table 2 Sorption Studies
Very sandy soil; very low adsorption
Step 3: Examine Sensitivity to
Phase Separation
Sample
[Surf.
A]
[Surf.
B]
[Salt A]
ID
P-0
P-100
P-300
P-500
P-800
wt%
0.75
0.75
0.75
0.75
0.75
wt%
0.19
0.19
0.19
0.19
0.19
wt%
1.6
1.6
1.6
1.6
1.6
[Salt B]
[Calcium
Chloride]
Presence of
Precipitate
wt%
0.1
0.1
0.1
0.1
0.1
ppm
0
100
300
500
800
Yes/No
No
No
No
No
No
Table 3 Precipitation and Phase Separation Tests
Note: * No phase separation within the first day of
observation
Presence
of
Separation
Yes/No
Yes*
Yes*
Yes
Yes
Yes
Step 4: Mobility Ratio
Solution
NAPL
Surfactant/Polymer (S/P)
Solution
Surfactant/Polymer/Alkaline
(S/P/A) Solution
Polymer μ(Average)
(ppm)
(cp)
0
100
300
500
800
1,500
0
300
500
500
800
1,500
1.4181
1.4046
1.6949
1.9367
2.7654
3.3162
3.7507
1.4046
2.0927
2.6748
2.6748
3.9592
4.2944
Table 4 Viscosity of Different Solutions
Note: m(average) is the average viscosity shown in the
unit of centipoise (cp)
Step 5: Optimize Injection Sequence
Column Test #
Description
% Recovery
Note
1
Surfactant only
99.49
Observed some surfactant retardation
2
2PV Surfactant/Polymer
99.93
Mobilization started on the second
PV of surfactant injection
3
2PV Surfactant/Polymer/Alkaline
99.94
Mobilization started on the second
PV of surfactant injection
4
0.2PV P/A, 1PV S/P/A, 0.2PV P/A at
1500 ppm polymer*
99.93
More mobilized NAPL in the first PV
of mobilization
5
0.2PV P/A, 1PV S/P, 0.2PV P/A at 500
ppm polymer
99.93
More solubilization observed when
compared to column test #6
6
0.2PV P/A, 1PV S/P/A, 0.2PV P/A at
500 ppm polymer
99.94
More mobilization observed when
compared to column test #5
7
0.05PV P/A, 1PV S/P, 0.05 PV P/A at
500 ppm polymer
99.93
When compared to column 8, less
amount of NAPL mobilized and
more solubilized NAPL
The NAPL was mobilized out from
the column 3-5 minutes before
column test #7 and there was a higher
amount of NAPL mobilized out from
column when compared to column
test #7
8
0.05PV P/A, 1PV S/P/A, 0.05 PV P/A
at 500 ppm polymer
99.93**
9
0.05PV P/A, 1PV S/P, 0.2 PV P/A at
100 ppm polymer
94.6
Less amount of mobilized oil when
compared to 500 ppm polymer
10
0.05PV P/A, 1PV S/P/A, 0.05 PV P/A
at 100 ppm polymer
90.29
Less amount of mobilized oil when
compared to 500 ppm polymer
11
1 PV S/A, no polymer
92.97
Solubilization mechanism is
dominant
Table 5 Summary of 1-D Column
Tests
*S: surfactant, P: polymer, A: alkaline;
PV = pore volume
**yellow highlighted: the optimal
surfactant candidate based on the
performance of NAPL recovery and
the recovery mechanism (mainly
mobilization)
Pilot Study Overview
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Footprint was < 1/8 acre; well spacing of 25 ft.
2 pore volumes of surfactant at 0.94 wt %
2 nine-spot patterns
Submersible pumps recover NAPL/water/surfactant
Process equipment
• oil/water separator
• injection mixing tanks/pumps
• injection/extraction manifolds
• influent/effluent pumps
• carbon vessels
Mixing & Holding Tanks, O/W
Separator, GAC Canisters
Site Map
Timeline
• Pre-Flush – 1 pore volume
– 31 Aug 09 – 6 Sep 09
– Set BioTraps on 3 Sep 09
– Tracer (NaBr) injected 4 – 5 Sep 09
• Surfactant Flush – 2 pore volumes
– 6 – 21 Sep 09
– Groundwater sampled on 10 and 17 Sep 09
– Surfactant first observed
– EX-02 and OWS on 20 Sep 09
– EX-01 on 23 Sep 09
Timeline
• Post Flush - 5 pore volumes
– 21 Sep 09 – 1 Nov 09
– Applied vacuum on extraction wells on 25 Sep 09
– Reconfigured injection/extraction on 20 Oct 09
– Groundwater sampled on 1 Oct 09 and 2 Nov 09
– BioTraps 7 Oct 09
– Injected remaining treated water 3 – 6 Nov 09 to empty tanks
Mixing Tanks
Size: 18,000 Gallons
Transfer Pump
Mixing Tanks
Size: 18,000 Gallons
Mixer with propeller
Injection Manifold
Flow Meters and Flow Controllers
Flow Meter
Flow Control Unit
Remediation and Monitoring Wells
Oil/Water Separator
45 min. Residence Time
Surfactant Concentrate
330 Gallon Totes
Added Manually to Mixing Tank
Quality Control Check
NaCl: 0.3-1.7% with 0.1% increment
2.5
min
3 min
Phase Behavior Test
Phase Behavior Test
NaCl: 0.3-1.7% with 0.1% increment
1 hour
Data Assessment
• Pre-Pilot Conditions
– API Model estimated 2,300 gal LNAPL
• Results
– Total LNAPL Recovery was 2,740 gal
– API Model estimated140 gal remained
LNAPL Thickness/Distribution
API Model
Soil Sampling Results - Upper
Soil Sampling Results - Middle
Soil Sampling Results - Lower
11/3
11/1
Sys down from 5 am
1 Nov tp 4 pm 2 Nov
for GW sampling
80
10/30
100
10/28
10/26
10/24
10/22
10/20
10/18
10/16
10/14
10/12
10/10
10/8
10/6
120
1,500
60
1,000
40
500
20
0
0
Cumulative Recovery (gal)
End of Post-flush (PV5)
New configuration
13-hr power outage
Cum_OWS
10/4
10/2
Sys down to readjust EX-01
Vacuum applied
2-hr Power outage
Post-flush started
Cum_total
9/30
9/28
9/26
9/24
9/22
Daily_OWS
9/20
Surfactant-flush started
Daily_tanks (estimated)
9/18
9/16
9/14
9/12
9/10
9/8
180
9/6
Tracer injection
200
9/4
140
Pre-flush started
160
9/2
8/31
Daily Recovery (gals/day)
LNAPL Recovery
Oasis SEAR Pilot Study LNAPL Recovery
Note:
Vacuum truck events done on
9, 14, 20, 21, 27 Oct, and 9 Nov 09
3,000
2,500
2,000
Extraction Well - Partial Plugging
Key Findings
• Motivation for full-scale implementation
– Significant LNAPL removal - 2,740 gal
– Significant reduction in LNAPL thickness
– Significant reduction in soil TPH-DRO
– Hydraulic control achieved and maintained
– No increase in dissolved-phase concentrations
– Optimized surfactant formulation
Key Findings
• Lessons learned as a result of the pilot study
– Heterogeneous NAPL thickness along perimeter
– Heterogeneous stratigraphy
– Mobilization of fine sand
– Emulsification within process equipment
• Fixes
– Better placement of well screens
– Improved well locations
– Improved surfactant formulation
– Longer residence times in oil/water separator
Full Scale Implementation
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Final review with State Regulatory Agency, Military Base
Groups on November 12th
Decision for full scale (3.6 acres) made - RFP issued
Implementing in 3 parcels of 1.2 acres each
System installation in May 2010
Surfactant injection in June 2010
Post surfactant flush to be finished November 2010