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Selecting the Most Cost Effective Technologies for PFAS Treatment
Steve Woodard, Ph.D., P.E.
Presentation outline
• PFAS case study: site history & background
• Mechanisms of PFAS removal
• Pilot test at Pease AFB former Fire Training Center (FTC)
• Full-scale design and implementation
• PFAS removal results
• Lessons learned
• Drinking water case study
• Technology selection - general approach
Site history and background: Former Pease AFB
• Decades of fire fighting training activities on Site
• Other sources of PFAS contamination include fire station, misc. spills, response to aircraft fire, etc.
• PFAS detected in drinking water during 2014 sampling event
• Public advocacy groups formed ✓ PFAS Blood Testing Program✓ Risk assessment and remediation
• High profile site that drew local and regional media attention
Former fire training center
Haven Well
PFAS contamination source – former FTC
• Early days of FTC remediation: jet fuel cleanup
• Duel-phase extraction system
• Focus on BTEX/ VOCs
• Groundwater treatment system shut down – “cleanup completed”
• Restarted treatment using GAC in 2014 after discovery of PFAS in groundwater
• Frequent GAC changeouts – every 3 weeks
• Air Forces began searching for a better solution
Properties of PFAS – important for treatment
_
PFOS PFBA
• Hydrophobic fluorinated carbon chain – “tail”
• Anionic sulfonate or carboxylate group – “head”
12
34
5 6 78
12
3 4
Head
Tail
Ion exchange resin utilizes both IEX and adsorption
PFOS Molecule
Simplified Resin Bead
Dual mechanism of removal: IEX and adsorption
GAC only uses Adsorption
SORBIX™ A3F regenerable resin process flow
Regenerable IEX ResinSORBIX A3F
© Amec Foster Wheeler 2016.8
Pilot test process flow diagram
Influent PFAS concentrations
Former FTC pilot test: IEX resin vs. GAC
© Wood 2018.10
Processpumps
Cartridge filters for solids removal
GAC (front) and resin (rear)
vessels
PFOA & PFOS breakthrough at 5-min EBCT
Regenerable resin selected for full-scale implementation, based on: • Superior performance• Lower lifecycle cost
Full-scale design and implementation
Full-scale resin system
Resin regeneration and distillation/reuse
Influent and effluent Total PFAS (13 detected)
Challenges and lessons learned
PFAS contamination of City of Portsmouth water supply
• April 2014 – NHDES contacts City of Portsmouth to sample drinking water wells
• May 2014 – City staff are notified that the PFOS concentration in the Haven Well is 2,500 ppt, more than 10x the EPA Health Advisory Standard
• City shuts down Haven well
• Begins implementation of temporary GAC system to treat water from Smith and Harrison wells
• Keeping track of Air Force’s developments at FTC
Fire Training Center
Haven Well
Harrison and Smith
Wells
Former Pease Air
Force Base
Map courtesy of Air Force Civil Engineering Center
*
Haven Well pilot test
Activated Carbon versus ECT’s SORBIX single-use resin
Side-by-Side test
Inlet total PFAS = 3 ug/l (ppb)
Removal comparison – PFOA + PFOS
City shutdown GAC pilot
GAC IX Resin
Short-chain sulfonate - PFBS
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Co
nce
ntr
atio
n (p
pb
)
Date
GAC - PFBS
GAC 10.0 min
GAC 5.0 min
GAC 2.5 min
INFLUENT
First sample at 574 gals Treated
2860 BVs
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Co
nce
ntr
atio
n (p
pb
)
Date
IX - PFBS
IX 10.0 min
IX 5.0 min
IX 2.5 min
INFLUENT
GAC IX Resin
Lifecycle cost comparison
Treatment Option Capital CostAnnual Operating
CostPresent Worth
Cost Cost Reduction
GAC $2,474,000 $380,000 $7,633,000 -
Resin $1,990,000 $97,500 $3,315,000 50%
Twenty-Year Present Worth Analysis (USD)800-gpm Drinking Water Treatment Plant
Source: Weston & Sampson (independent consultant)
PFAS technology selection – general approach
• Example of cost-effective GAC application
• High influent chloride concentrations
• Need to remove short-chain PFCAs
• Has co-contaminants, such as VOCs
• Example of cost-effective single use resin application
• “Normal” chloride concentrations (< 150 mg/l)
• Need to remove all PFAS compounds, or just PFOA and PFOA
• No VOC co-contaminants
• Example of cost-effective regenerable resin application
• Elevated influent PFAS (>20 ug/l)
• Treatment objective = PFOS + PFOA < 70 ng/l
• Client wants to minimize waste generation
• Influent PFAS compound mix and concentrations
• Effluent PFAS regulations/treatment objectives
• Unit cost of power ($/kWh)
• Co-contaminants and foulants
• Inorganic anion concentrations, esp. chloride
• Disposal type/location/cost
• Liability management
• Footprint
• Lifecycle cost analysis
Important Factors