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Removal of perfluoroalkyl acids from the drinking water production chainChristian Eschauzier and Pim de Voogt.
2Watercycle Research Institute
Outline
• Introduction
• Sources of PFAA to groundwater
• Behavior of PFAA in drinking water production
• Conclusions
2
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Perfluoroalkyl acids - properties
• Chain length varies nCF2 +F = 3 to 17
• Very persistent, possibly bioaccumulative and toxic.
• Water solubility: 9.5 g/L � high!
• Multiple uses
Acid
hydrophilic
Perfluoroctanoic acid (PFOA)
Very stable bond
Fully fluorinated chain
hydrophobic
Introduction
• PFAA in environmental compartments
• Surface water, biota, air
• Human serum
• Exposure pathways (denHollander, 2010)
• Drinking water(Vestergren, 2009)
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5Watercycle Research Institute
Introduction
Perfluoroalkyl acids in drinking water: Sources, fate and removal.
• Sources: to groundwater and surface waters
• Fate: During treatment
• Removal: Affinity adsorption
6Watercycle Research Institute
Introduction
6
•PFAA in surface waters
•Surface vs. Drinking water
•Background concentrations:
• low ng/L level e.g. Ericson(2009)
•In surface waters or groundwater contaminated areas: high concentrations
•Unknown concentrations in Dutch drinking water •Info mainly focuses on PFOA and PFOS•Info does not focus on different treatment steps
Takagi, 2008
PFOA
0
50
100
150
200
250
300
350
400
450
Mar-06 Oct-06 Apr-07 Nov-07 Jun-08 Dec-08 Jul-09 Jan-10
Datum
Co
nc
. n
g/L
Hochbehälter „Vogled“
Übergabeschacht Marktl
Hochbehälter Eschelberg
LGL, 206 to 2009
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• Low concentrations in general (ng/L)
• Much less info available
• Sources
• fire fighting practise
• Landfills
• Producing/using companies
• Drinking water treatment less thorough
7Watercycle Research Institute
Sources to groundwater
8Watercycle Research Institute
Case study
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Groundwater: Case study
• Chain length dependent behaviour
• PFOS not mobile
• Point source: Landfill
• Diffuse source: Rainwater
• PFOS mobility
• Removal from groundwater…?
9Watercycle Research Institute
Fate: During treatment
•Drinking water production of Amsterdam•Two sampling rounds •Hydrological retention time taken into account•More than 60 samples analyzed in duplicate over two seasons
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11
F
Drinking
Water
Production
from river
Rhine water
in NL
with sampling
points
Drinkingwater treatment
12Watercycle Research Institute
G
H I
J
Drinkingwater treatment
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PFAA behaviour during DW treatment
•Similar PFAA profile in
the surface water as through
the pre-treatment process
•PFAA present in all samples
• PFBA (52 ng/L max)
• PFBS (42 ng/L max) (in raw water)
Inf.
Lek c
anal
Effl. c
oagula
tion
Effl. r
apid
san
d filtr
atio
n
0
5
10
15
Co
nc.
ng
/L
Afte
r dune
passa
ge
Effl. r
apid
san
d filtr
atio
n
Effl. o
zonat
ion
Infl
GAC fi
ltrat
ion
Effl. F
irst G
AC fi
ltrat
ion
Effl. G
AC fi
ltrat
ion
Drin
king w
ater
0
5
10
PFBA
PFHxA
PFOA
PFNA13
36
28
32
Inf.
Lek c
anal
Effl. c
oagula
tion
Effl. r
apid
san
d filtr
atio
n
0
10
20
30
40
Co
nc.
(ng
/L)
Afte
r dune
passa
ge
Effl. r
apid
san
d filtr
atio
n
Effl. o
zonat
ion
Infl
GAC fi
ltrat
ion
Effl. F
irst
GAC fi
ltrat
ion
Effl. G
AC fi
ltrat
ion
Drin
king w
ater
0
10
20
30PFBSPFHxSPFOS
A B
C D
Results 2GAC filtration
•No removal of PFAA throughout the purification process except for GAC filtration.
•No removal of ≤C8 carboxylic acids and ≤ C5 sulfonic acids
•Filter age dependency of the removal capacity
-100
-80
-60
-40
-20
0
20
Lead PFCALag PFCA
C5 C6 C7 C8 C9 C10
Lead PFSALag PFSA
ALkyl chain length
Rem
oval (%
)
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15Watercycle Research Institute
PFOA
0.1 1 10 1000.1
1
10
100
JapanUSUK
Influent (ng/L)
Eff
luen
t (n
g/L
)
PFOS
0.1 1 10 1000.1
1
10
100
JapanUSUK
Influent (ng/L)
In a broader perspective
Conclusions
• From all tested processes only GAC removes PFAA
• No removal of short chained PFAA• PFBS which is used PFOS substituent
• PFHxA which is partly replacing PFOA
• Margins to existing guidelines are large
• 300 ng/L PFOS + PFOA
• PFBA 7000 ug/L (Wilhelm, 2010)
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17Watercycle Research Institute
Acknowledgments
• EU project PERFOOD (KBBE-227525)
• TTIW Wetsus
• BTO
• Wellington Laboratories
18Watercycle Research Institute