in-situ pfas remediation using colloidal activated...
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In-Situ PFAS Remediation Using Colloidal Activated Carbon
Copyright Porewater Solutions (2019) 1
Presented By Grant R. Carey, Ph.D.
Ottawa, Ontario, Canada [email protected]
CACBarrier
Co-Author Acknowledgement
Copyright Porewater Solutions (2019) 2
Seyfollah Gilak Hakimabadi Dr. Anh Pham Rick McGregor Dr. Brent Sleep
Agenda
1. Colloidal Activated Carbon (CAC) Concepts
2. Canadian Site – PFOS Longevity Modeling 3. AFFF Site Longevity Assessment
• Groundwater plumes (PFOS, PFOA, PFHxS)
• Isotherm Results
• CAC Longevity modeling
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Colloidal Activated Carbon Concepts
4 Copyright Porewater Solutions (2019)
Section 1
Activated Carbon
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GAC 0.5-1 mm
Granular Activated Carbon 0.5 to 1 mm
Powdered Activated Carbon 0.01 to 0.1 mm
Colloidal Activated Carbon 0.001 to 0.002 mm
750 microns 25 microns 1.5 microns
GAC
PAC
CAC
In-Situ Colloidal Activated Carbon (CAC)
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SEM Image of CAC attached to sand grains.
Courtesy of Regenesis
• Polymer enables distribution and prevents clogging
• Polymer biodegrades/ flushed downgradient
• Low-pressure injections minimize preferential pathways and enhanced distribution (Rick McGregor, 2018)
Courtesy of Rick McGregor, IRSL
Conceptual Cross-Section
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Flow
PFAS Plume
Ground Surface
Vadose Zone
PFAS Mass Flux Reduction Using CAC Injection
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Flow
Injection Wells
CAC Zone PFAS Plume
PFAS Mass Flux Reduction Using CAC Injection
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Flow
CAC Zone PFAS Plume Detachment
PFAS Plume
PFAS Mass Flux Reduction Using CAC Injection
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Flow
CAC Zone PFAS Plume Detachment
PFAS Plume
Longevity depends on:
• fCAC
• CAC zone length
• Regulated PFAAs
• Co, velocity
• Isotherms
• Competitive effects
After CAC saturation:
• Additional injection or new alternative
Canada Site Case Study: CAC Longevity Modeling
Section 3
11 Copyright Porewater Solutions (2019)
Remediation Journal, 2018 Remediation Journal, 2019
Central Canada Site: Furniture Manufacturer • Petroleum hydrocarbons, & PFOS-PFOA at low
ug/L
• Remedy implemented by Rick McGregor (2016) • CAC injected with ORC
• Low-pressure injections to avoid fracturing soil
• 3 m well spacing
• Single injection event over one week period
• Total treatment cost: $100,000
• Two years of monitoring data indicate that PFAS remain below target criteria
Rick McGregor, President InSitu Remediation Services Limited
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PFOS Concentrations versus Time
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W-1 MW-1MW-11
MW-2
MW-4
MW-5
MW-7
MW-8
0 5 10
Scale, in meters
CAC Zone
0
200
400
600
800
1000
1200
1400
Jan-16 Jul-16 Dec-16 Jul-17 Dec-17 Jul-18
Conc
entr
atio
n (n
g/L)
Date
MW-1
0
200
400
600
800
1000
1200
1400
Jan-16 Jul-16 Dec-16 Jul-17 Dec-17 Jul-18
Conc
entr
atio
n (n
g/L)
Date
MW-2
0
200
400
600
800
1000
1200
1400
Jan-16 Jul-16 Dec-16 Jul-17 Dec-17 Jul-18
Conc
entr
atio
n (n
g/L)
Date
MW-5
0
200
400
600
800
1000
1200
1400
Jan-16 Jul-16 Dec-16 Jul-17 Dec-17 Jul-18Co
ncen
trat
ion
(ng/
L)Date
MW-8
Pre-injection Pre-injection
Pre-injection Pre-injection
Source Zone
MW-90 5 10
Scale, in metersScale, in meters
0 5 10 Flow
N
Detected
Non-detect
PFSA Radial Diagrams (2017)
Copyright Porewater Solutions (2019) 14
MW-1
MW-2
MW-5
MW-8
MW-90 5 10
Scale, in meters
101001,00010,000
PFOSA
PFDS
PFOS
PFHxS
PFBS
October 2017
Spring 2016
March 2018: all ND at MW-1, MW-8
CAC Zone
Source Zone
Flow
N
Concentrations in ng/L
Non-detect (plotted at one-half of the detection limit)
PFCA Radial Diagrams (2017)
Copyright Porewater Solutions (2019) 15
MW-1
MW-2
MW-5
MW-8
MW-90 5 10
Scale, in meters
101001,00010,000
PFDoA
PFUnA
PFDAPFNA
PFOA
PFHpA
PFHxAPFPeA
PFBA
Concentrations in ng/L
Non-detect (plotted at one-half of the detection limit)
October 2017
Spring 2016
March 2018: all ND at MW-1, MW-8
CAC Zone
Source Zone
Flow
N
ISR-MT3DMS Model: PFOS Mass Balance in CAC Zone
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Tota
l PFO
S M
ass
On-
Site
(mg)
a) Prior to CAC Injection b) Immediately after CAC Injection
0
100
200
300
400
500
1 20
100
200
300
400
500
Carey et al. (2019)
PFAS-CAC Isotherms
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15 mL plastic test tube Rotate for 1-3 day
Polycarbonate ultracentrifuge tube
Centrifugation
mass-labelled standard
& methanol
HPLC vial
Plumestop®PFAS 1 – 1000 ug/L
Courtesy of Dr. Anh Pham, University of Waterloo
Note: Site-specific isotherms and pilot tests are recommended.
Seyfollah Gilak Hakimabadi
Dr. Anh Pham [email protected]
Isotherms: AFFF Site Groundwater Sample
18
AnalyteResult(ug/L)
PFBS 2.71PFPeS 2.46PFHxS 65.5PFHpS 3.13PFOS 208PFDS <0.020
Total PFSAs: 281.8
AnalyteResult(ug/L)
PFBA 1.14PFPeA 10PFHxA 11.6PFHpA 2.73PFOA 20.8PFNA 0.552PFDA 0.092
PFUnDA <0.020PFDoDA <0.020PFTrDA <0.050PFTeDA <0.050Total PFCAs: 46.9
AnalyteResult(ug/L)
FOSA 2.04MeFOSA <0.050EtFOSA <0.050MeFOSE <0.050EtFOSE <0.020
MeFOSAA <0.020EtFOSAA <0.0204:2 FtS 0.226
6:2 FtS 40.48:2 FtS 17.5
10:2 FtS <0.020Total Precursors: 60.2
PFSAs PFCAs Precursors
Copyright Porewater Solutions (2019)
TOC: 23.8 mg/L
Note: GW sample was provided by Dr. Charles Schaeffer (CDM).
PFAS-CAC Isotherms
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𝑆𝑆 = 𝐾𝐾𝑓𝑓𝐶𝐶𝑎𝑎 Freundlich Isotherm:
In-situ Retardation Coefficient: 𝑅𝑅𝐶𝐶𝐶𝐶𝐶𝐶 = 1 +ρ𝐵𝐵θ
𝑓𝑓𝐶𝐶𝐶𝐶𝐶𝐶𝐾𝐾𝑓𝑓𝑎𝑎𝐶𝐶𝑎𝑎−1
Seyfollah Gilak Hakimabadi
Dr. Anh Pham [email protected]
0
5
10
15
20
25
30
35
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08
Soil
Conc
entr
atio
n (m
g/g)
Aqueous Concentration (mg/L)
Solution type: PFOS-only AFFF site sampleKf (mg1-a La / g): 143 4.9
a (dimensionless): 0.59 0.24
GW sample from AFFF site
Simulated PFOS Plume Detachment
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0.97 1.45
<0.02
0.780.37
<0.02
<0.02
0.28
<0.02
<0.02
0.57
0 10 20
Scale, in meters
PFOS (ug/L)
a) Prior to CAC injection
Source area
b) 180 days after CAC injection
N
Source area CAC Zone
Flow
Flow
Carey et al. (2019)
PFOS Md = 0.6 g/y
Simulated PFOS Plume versus Time
Copyright Porewater Solutions (2019) 21
a) t=1 year
a) t=10 years
a) t=20 years
a) t=30 years
a) t=40 years
a) t=50 years
0 10 20
Scale, in meters
PFOS (ug/L)
CAC Zone Source Area
N
AFFF Site Model
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Section 3
Groundwater Plumes
23
0 500 1000
Scale, in feet
PFOA PFOS PFHxS
N N N
GV to 10 ug/L
GV: Guidance Value
10 to 100 ug/L
100 to 1,000 ug/L
>1,000 ug/L
Copyright Porewater Solutions (2019)
GV = 0.07 ug/L GV = 0.07 ug/L GV = 0.56 ug/L
Former FTA Former FTA Former FTA
Note: plumes based on GW samples collected in 2011 through 2015
Plume Characteristics
24 Copyright Porewater Solutions (2019)
PFHxS PFOS PFOAA 992 321 213B 92 43 32C 74 42 32D 90 54 41E 0.9 n/a n/a
Mass Discharge (g/y)Transect
0 500 1000
Scale, in feet
A
N
B
C
D
E
0.07 to 10 ug/L
10 to 100 ug/L
100 to 1,000 ug/L
>1,000 ug/L
PFHxS PFOS PFOAA 617 345 206B 106 46 74C 70* 40* 35*D 60* 35* 35*E 0.44 0.008 0.05
Maximum Concentration (ug/L)Transect
* Conservative Estimate
Groundwater velocity ~ 30 m/year
PFHxS
x = 150 ft
x = 700 ft
x = 1300 ft
x = 2100 ft
Former FTA
Preliminary PFAS-CAC Isotherms
25 Copyright Porewater Solutions (2019)
Kf : mg1-a La / g; a: dimensionless
Seyfollah Gilak Hakimabadi
Dr. Anh Pham [email protected]
K f a K f aPFOS 143 0.59 4.9 0.24PFOA 25 0.56 0.5 0.22PFHxS 41 0.42 1.2 0.22PFBS 12 0.68PFBA
PFPeAPFHxA
Single Species AFFF Site GW SampleAnalyte
IN PROGRESS
1-D PFAS CAC Longevity Model
Copyright Porewater Solutions (2019) 26
Co*
Velocity: 30 m/year
CAC Zone Breakthrough Time?
12 to 24 m
* Based on Transect D concentrations PFOA: 35 ug/L PFHxS: 60 ug/L
Note: PFOS longevity longer than PFHxS and PFOA, so was not modeled.
fCAC: 0.02% to 0.2%
0
10
20
30
40
50
60
70
CAC
Long
evity
(yea
rs)
PFOA PFHxS
CAC Longevity for PFOA and PFHxS at AFFF Site
Copyright Porewater Solutions (2019) 27
4 y 6 y 10 y
15 y 20 y
30 y
40 y
60 y
fcac = 0.02% fcac = 0.05% fcac = 0.10% fcac = 0.20%
Longevity α fcac and LENGTH of sorption zone
Canadian Site
Potentially Attainable
Conclusions and Recommendations • CAC is viable as an interim remedy for PFAS mass flux
reduction at some sites, but not all sites • May be able to offset longer term costs until more
regulatory and technological certainty • Additional laboratory and field-scale testing are needed,
and in progress • Variation in sorption capacity at range of PFAS sites? • Performance with shorter-chain PFAAs? • Attainable fCAC? • Competitive sorption effects?
Copyright Porewater Solutions (2019) 28
• PFAS isotherms • PFCAs, PFSAs, FtS • Sensitivity to various conditions
• CAC colloidal transport • Fate and transport model development • Field-scale pilot tests • Site characterization & visualization methods • Seeking GW samples
PFAS Remediation Research Group
• Univsersity of Waterloo (Dr. Anh Pham) • University of Toronto (Dr. Brent Sleep) • Carleton University (Dr. Paul Van Geel) • Porewater Solutions (Dr. Grant Carey) • IRSL (Rick McGregor)
29 Copyright Porewater Solutions (2019)
Questions?
30
Grant Carey, Ph.D. Porewater Solutions
613-270-9458
[email protected] www.porewater.com
Copyright Porewater Solutions (2018)
PFOS Sorption Isotherms: GAC, PAC, and CAC
0
1
10
100
1,000
10,000
100,000
1,000,000
0.0000001 0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000
Batc
h Te
st S
orbe
d Co
ncen
trat
ion
(mg/
Kg)
Aqueous Concentration (mg/L)
CAC-Pham & Gilak (2018) CAC-Regenesis
GAC-Yu et al (2009) PAC-Yu et al (2009)
GAC-Senevirathna et al (2010) GAC-Hansen et al (2010)
PAC-Hansen et al (2010) Ochoa-Herrera & Sierra-Alvarez (2008) - high Cw
Ochoa-Herrera & Sierra-Alvarez (2008)-lower Cw CAC-extrapolated
Carleton U. (AFFF site GW)
Regenesis (pure solution)
Copyright Porewater Solutions (2019) 32
GAC Bench-Scale Test (Based on McCleaf et al., 2017)
y = 0.9466e-2E-05x R² = 0.9033
y = 0.9939e-1E-05x R² = 0.9251
y = 1.0027e-8E-06x R² = 0.9593
y = 1.0154e-7E-06x R² = 0.9578
y = 1.2437e-7E-05x R² = 0.9014
y = 0.9897e-3E-05x R² = 0.8716
-20%
0%
20%
40%
60%
80%
100%
0 20,000 40,000 60,000 80,000 100,000 120,000 140,000
Rem
oval
Effi
cien
cy
Pore Volumes
Removal Efficiency Decline Rates: PFCAs (shorter chained)
PFBA PFPeA PFHxA PFHpA
PFOA PFNA PFBA-Trend PFPeA
Expon. (PFHxA) Expon. (PFHpA) Expon. (PFOA) Expon. (PFNA)
Expon. (PFBA-Trend) Expon. (PFPeA)
Source: McCleaf et al. (2017)
0.1 m
0.05 m
Velocity = 61 m/day Retention time = 2 minutes
Length = 0.1 m Mass flux = 0.002 g/m2/day
Desorption
Carey et al. (2019, in preparation)
y = 1.011e-4E-06x R² = 0.9539
y = 1.0074e-1E-05x R² = 0.9058
y = 1.0258e-7E-06x R² = 0.9653
y = 1.0255e-4E-06x R² = 0.9454
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 20,000 40,000 60,000 80,000 100,000 120,000 140,000
Rem
oval
Effi
cide
ncy
Pore Volumes
FOSA
PFBS
PFOS
PFHxS
GAC Bench-Scale Test (Based on McCleaf et al., 2017)
Copyright Porewater Solutions (2019) 34
GAC Full-Scale Pilot Test (Appleman et al., 2014)
0%
20%
40%
60%
80%
100%
0 50,000 100,000 150,000 200,000Co
ncen
tratio
n (u
g/L)
nPV
PFOS
Lead Effluent Lead Effluent - ND Lag Effluent Lag Effluent ND
0%
20%
40%
60%
80%
100%
0 50,000 100,000 150,000 200,000
Conc
entra
tion
(ug/
L)
nPV
PFOA
Lead Effluent Lead Effluent - ND Lag Effluent Lag Effluent ND
-20%
0%
20%
40%
60%
80%
100%
0 50,000 100,000 150,000 200,000
Conc
entra
tion
(ug/
L)
nPV
PFHxA
Lead Effluent Lead Effluent - ND Lag Effluent Lag Effluent ND
-80%-60%-40%-20%
0%20%40%60%80%
100%
0 50,000 100,000 150,000 200,000
Conc
entra
tion
(ug/
L)
nPV
PFBA
Lead Effluent Lead Effluent - ND Lag Effluent
Carey et al. (2019, in preparation)
LEAD VESSEL
LAG VESSEL
1 2
Velocity = 500 m/day Retention time = 7 minutes
Length = 2.7 m Mass flux = 0.2 g/m2/day
Breakthrough Lag Period
Copyright Porewater Solutions (2019) 35
Influence of Activated Carbon Size on PFOS Sorption
10,000
100,000
1,000,000
10,000,000
100,000,000
1,000,000,000
1 10 100 1000
Effe
ctiv
e K
d (L
/Kg)
Activated Carbon Particle Size (um)
? PAC-GAC Data from Xiao et al. (2017)
0 10 20
Scale, in meters
PFOS (ug/L)
0.6 0.8 1 1.2 1.4
Injection Well Locations and Vertical Carbon Distribution
36 (Modified from McGregor, 2018)
CAC Zone PFOS Source Area
Radius of influence: >4 m Average fCAC: 0.02%
Redox Radial Diagrams
Copyright Porewater Solutions (2019) 37
-300-200-1000100200300
0.1
1
10
0.1 1 101
10
100
ORP(mV)
DO (mg/L)
Nitrate(mg/L)
Sulfate (mg/L)
MW-1
MW-2
MW-5
MW-8
MW-1
MW-2
MW-4
MW-5
MW-7
MW-8
MW-11
MW-1
MW-2
MW-5
MW-8
a) Spring 2016 (pre-injection)
b) April 2017 (13 months after injection)
c) Oct. 2017 (19 months after injection)
Aerobic Anaerobic
CAC Zone
CAC Zone
N