selecting the most cost effective technologies for pfas ... · selecting the most cost effective...

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

Steve Woodard207-210-1551swoodard@ect2.com

Questions?