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Treating Emerging Contaminants
Evaluation of the removal efficiency of activated carbon on
PFAS in drinking water
Wendy Schultz
Per- and Polyfluoralkylsubstances (PFAS)
Most people in the United States have been exposed to PFAS and have PFAS in their blood.
Data Source: Centers for Disease Control and Prevention. Fourth Report on Human Exposure to Environmental Chemicals (January 2017).
Michigan PFAS Sites
Michigan PFAS Sites
Project Objective
The objective of this project was to assess the effectiveness of granular activated carbon for removing PFAS from drinking water sources.
Project Drivers
Safe water for our customers
Meeting future regulations
Agenda / Topics
Overview of PFAS and Granular Activated Carbon
Background of the finding the problem
Project and Methodology
Key Findings/Results
Conclusion/Future
What are PFAS ?
What are PFAS ?
PFCs
What are PFAS?
PFAS
Perfluoroalkyl Polyfluoroalkyl
Focus on two perfluoroalkylsubstances
CCCCC
CCC
C
CCC
CC C
C
>3,000 Man-made chemicals
Fire-fighting foam
Whiteman AFB, Missouri
B2 Stealth Bomber
B2 Stealth Bomber
Fire-fighting foam
Industrial Sites
WWTP
Landfills
Water & Air
Released into the food chain
Persists indefinitely in the environment
Builds up
Human Exposure
Found in fresh food
Found in fast food packaging
Found in fast food
Found in home-cooked food
Found in house dust
Found in cleaning products
Found in stain-resistant coatings
Found in personal care items
Found in fish
PFAS in Michigan fish
Granular Activated Carbon (GAC)
How is GAC made?
Why is it called activated carbon?
What makes it granular activated carbon?
2 grams of GAC
How does GAC work?
Adsorption vs. Absorption
(think Adhere vs. Absorb)
Adsorption Capacity
Third Unregulated Contaminant Monitoring Rule (UCMR3)
Contaminant (ppt)Dec
2013Mar
2014Jun
2014Sep
2014
perfluorooctanesulfonic acid (PFOS) ND 43.0 ND ND
perfluorooctanoic acid (PFOA) ND ND ND ND
perfluorononanoic acid (PFNA) ND ND ND ND
perfluorohexanesulfonic acid (PFHxS) ND ND ND ND
perfluoroheptanoic acid (PFHpA) ND ND ND ND
perfluorobutanesulfonic acid (PFBS) ND ND ND ND
PFOS and PFOA combined in the drinking water contamination near Rockford measured at 58,930 ppt.
Ann Arbor Water Treatment Plant
Ann Arbor Water Treatment Schematic
PRIMARY
FLOC
PRIMARY
SETTLING
CO2
RECARBSEC
SETTLING
Huron River
Water
LIM
EGAC
FILTRATION
Finished
Water
CL
2
Turb =10-20
pH = 10.8-11.2
TAlk =50-70
O3
OZONESEC
FLOC
SEC
RAP MIX
PRIMARY
RAP MIX
Well
Water
Well
Water
Turb = 2-20
pH = 7.8-8.2
TAlk = 275
Hard = 325
AM
PO
LYM
ER
CO2
PH
OS
PH
AT
E
NA
OH
FLU
OR
IDE
RECARB
Turb = 20-40
pH =10
TAlk =30-50
Turb =0.05-0.2
pH =9.3
TAlk =30-70
Hard =150
Ann Arbor Treatment Diagram(
Investigation
This Photo by Unknown Author is licensed under CC BY-NC-ND
Huron River
Water SupplyOptional statement
152 NPDES sites
Huron River
Image courtesy of Tim Kiser
Huron River PFAS
Ann Arbor Water Treatment Plant
Filter Gallery
Filter Gallery
Our usual configuration
6” sand
~18” GAC
Water out
Water in
29” GAC
Water out
Water in
Filter #1
Filter #15
6” sand
~18” GAC
Water out
Water in
Sampling Methodology
Filter #1 PFOS
Filter #1 PFOA
Filter #15 PFOS
Filter #15 PFOA
Project Summary
Conclusion
Future
AppendixReferences Buck et al 2011. Perfluoroalkyl and Polyfluoroalkyl Substances in the Environment: Terminology, Classification, and Origins. Integrated Environmental Assessment and Management. v7, (4), pp. 513–541.
CDC. 2009. Fourth National Report on Human Exposure to Environmental Chemicals. Atlanta, GA: Centers for Disease Control and Prevention. p. 247 –257.
