In-Situ PFAS Remediation Using Colloidal Activated...

In-Situ PFAS Remediation Using Colloidal Activated Carbon

Copyright Porewater Solutions (2019) 1

Presented By Grant R. Carey, Ph.D.

Ottawa, Ontario, Canada gcarey@porewater.com

CACBarrier

Co-Author Acknowledgement

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

Colloidal Activated Carbon Concepts

4 Copyright Porewater Solutions (2019)

Section 1

Activated Carbon

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

In-Situ Colloidal Activated Carbon (CAC)

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

PFAS Plume

Ground Surface

Vadose Zone

PFAS Mass Flux Reduction Using CAC Injection

Injection Wells

CAC Zone PFAS Plume

CAC Zone PFAS Plume Detachment

PFAS Plume

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

Remediation Journal, 2018 Remediation Journal, 2019

Central Canada Site: Furniture Manufacturer • Petroleum hydrocarbons, & PFOS-PFOA at low

• 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

rickm@IRSL.ca

PFOS Concentrations versus Time

W-1 MW-1MW-11

0 5 10

Scale, in meters

CAC Zone

Jan-16 Jul-16 Dec-16 Jul-17 Dec-17 Jul-18

Jan-16 Jul-16 Dec-16 Jul-17 Dec-17 Jul-18Co

L)Date

Pre-injection Pre-injection

Source Zone

MW-90 5 10

Scale, in metersScale, in meters

0 5 10 Flow

Detected

Non-detect

PFSA Radial Diagrams (2017)

MW-90 5 10

Scale, in meters

101001,00010,000

October 2017

Spring 2016

March 2018: all ND at MW-1, MW-8

CAC Zone

Source Zone

Concentrations in ng/L

Non-detect (plotted at one-half of the detection limit)

PFCA Radial Diagrams (2017)

MW-90 5 10

Scale, in meters

101001,00010,000

PFDAPFNA

PFHxAPFPeA

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

ISR-MT3DMS Model: PFOS Mass Balance in CAC Zone

a) Prior to CAC Injection b) Immediately after CAC Injection

Carey et al. (2019)

PFAS-CAC Isotherms

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 anh.pham@uwaterloo.ca

Isotherms: AFFF Site Groundwater Sample

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

𝑆𝑆 = 𝐾𝐾𝑓𝑓𝐶𝐶𝑎𝑎 Freundlich Isotherm:

In-situ Retardation Coefficient: 𝑅𝑅𝐶𝐶𝐶𝐶𝐶𝐶 = 1 +ρ𝐵𝐵θ

𝑓𝑓𝐶𝐶𝐶𝐶𝐶𝐶𝐾𝐾𝑓𝑓𝑎𝑎𝐶𝐶𝑎𝑎−1

0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08

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

0.97 1.45

0.780.37

0 10 20

Scale, in meters

PFOS (ug/L)

a) Prior to CAC injection

Source area

b) 180 days after CAC injection

Source area CAC Zone

Carey et al. (2019)

PFOS Md = 0.6 g/y

Simulated PFOS Plume versus Time

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

AFFF Site Model

Section 3

Groundwater Plumes

0 500 1000

Scale, in feet

PFOA PFOS PFHxS

GV to 10 ug/L

GV: Guidance Value

10 to 100 ug/L

100 to 1,000 ug/L

>1,000 ug/L

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

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

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

x = 150 ft

x = 700 ft

x = 1300 ft

x = 2100 ft

Former FTA

Preliminary PFAS-CAC Isotherms

Kf : mg1-a La / g; a: dimensionless

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

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%

PFOA PFHxS

CAC Longevity for PFOA and PFHxS at AFFF Site

4 y 6 y 10 y

15 y 20 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?

• 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)

Questions?

Grant Carey, Ph.D. Porewater Solutions

613-270-9458

gcarey@porewater.com www.porewater.com

PFOS Sorption Isotherms: GAC, PAC, and CAC

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

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)

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

0 20,000 40,000 60,000 80,000 100,000 120,000 140,000

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)

0.05 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 20,000 40,000 60,000 80,000 100,000 120,000 140,000

Pore Volumes

GAC Bench-Scale Test (Based on McCleaf et al., 2017)

GAC Full-Scale Pilot Test (Appleman et al., 2014)

0 50,000 100,000 150,000 200,000Co

tratio

Lead Effluent Lead Effluent - ND Lag Effluent Lag Effluent ND

0 50,000 100,000 150,000 200,000

-80%-60%-40%-20%

0%20%40%60%80%

0 50,000 100,000 150,000 200,000

Lead Effluent Lead Effluent - ND Lag Effluent

Carey et al. (2019, in preparation)

LEAD VESSEL

LAG VESSEL

Velocity = 500 m/day Retention time = 7 minutes

Length = 2.7 m Mass flux = 0.2 g/m2/day

Breakthrough Lag Period

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

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

-300-200-1000100200300

0.1 1 101

ORP(mV)

DO (mg/L)

Nitrate(mg/L)

Sulfate (mg/L)

a) Spring 2016 (pre-injection)

b) April 2017 (13 months after injection)

c) Oct. 2017 (19 months after injection)

Aerobic Anaerobic

CAC Zone

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