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Torsten C. Schmidt, Holger Lutze
POTENTIAL AND LIMITATIONS OF (ADVANCED) OXIDATION PROCESSES
IN WATER AND WASTEWATER TREATMENT
Cairo, February 19, 2013
Outline
Introduction/Overview of Oxidative Processes
Examples of our Recent Work: Lab Scale: Mechanistic Investigations with
Probe Compounds: Degradation of Micropollutants
Pilot Scale: Implementation of Ozonation in Drinking Water Treatment
(Full Scale: Advanced Treatment of Wastewater Effluents)
Conclusions and Outlook
Use of Oxidation Processes in Water
Treatment
Advantages:
• Constant process performance
• No disposal of concentrates or solids
(compared with AC sorption or membrane filtration)
Areas of Use:
• Drinking water
– Disinfection, Decolorization, Fe(II) and
Mn(II) Removal, Micropollutant Elimination
• Municipal wastewater
– Disinfection, Further elimination of micropollutants
• Industrial wastewater
• High purity industrial process waters
Important Considerations in Oxidative
Treatment Processes
Pollutants Oxidation CO2, H2O
Lifetime
Mechanisms
Kinetics
Transformation
products
Biodegradability
D Toxicological
effects
Scavenging by matrix
components
Possible loss of efficiency,
Oxidation byproducts
Prediction of
elimination based
on properties
possible?
Oxidation
Modified after U. von Gunten, eawag
Energy Demand/Carbon Footprint?
Estrogen Receptor
Effect? Effect
Oxidation
Estrogenically active compound
Effect of Oxidative Transformation:
Reduction of Estrogenicity
Transformation product
binds? binds
Modified after U. von Gunten, eawag
17b-Estradiole (E2)
Reduction of estrogenicity is proportional to
concentration decline of EE2
Lee et al. 2008
Reduction of Estrogenic Effects (EEEQ) of 17a-
Ethinylestradiole by Oxidative Processes
dose, M
0 5 10 15 20 25 30
Rel
ativ
e E
E2
or
EE
EQ
0.0
0.2
0.4
0.6
0.8
1.0
Relative EE20.0 0.2 0.4 0.6 0.8 1.0
Rel
ativ
e E
EE
Q
0.0
0.2
0.4
0.6
0.8
1.0
Chlorine
dose, M
0 5 10 15 20 25 30
Bromine
Relative EE20.0 0.2 0.4 0.6 0.8 1.0
Rel
ativ
e E
EE
Q
0.0
0.2
0.4
0.6
0.8
1.0
dose, M
0 5 10 15 20 25 30
Ozone
Relative EE20.0 0.2 0.4 0.6 0.8 1.0
Rel
ativ
e E
EE
Q
0.0
0.2
0.4
0.6
0.8
1.0
UV fluence, mJ/cm2
0 100 200 300 4000.0
0.2
0.4
0.6
0.8
1.0
OH radical
Relative EE20.0 0.2 0.4 0.6 0.8 1.0
Rel
ativ
e E
EE
Q
0.0
0.2
0.4
0.6
0.8
1.0
dose, M
0 5 10 15 20 25 30
Chlorine dioxide
Relative EE20.0 0.2 0.4 0.6 0.8 1.0
Rel
ativ
e E
EE
Q
0.0
0.2
0.4
0.6
0.8
1.0
dose, M
0 10 20 30 40
Ferrate
Relative EE20.0 0.2 0.4 0.6 0.8 1.0
Rel
ativ
e E
EE
Q
0.0
0.2
0.4
0.6
0.8
1.0
1
r2 = 0.96 r
2 = 0.99
1 1
r2 = 0.99
1
r2 = 0.99
1
r2 = 0.99
1
r2 = 0.99
Rel
ativ
e E
E2
or
EE
EQ
EE2
EEEQ
Modified after U. von Gunten, eawag 17a-Ethinylestradiole (EE2)
Oxidation + Biological Filtration:
Reduction of Toxic Effects in Whole Effluents
• Data from WWTP Regensdorf, CH:
Adapted from S. Zimmermann, EPFL
Elimination by ozonation and slow sand filtration in %
Bioluminescence
suppression
Acetylcholinesterase
suppression
Algae test
(photosynthesis)
Algae test
(growth)
YES Assay
Overview Advanced Oxidation Processes
UV based Ozone based H2O2 based
UV/H2O2
UV/O3
O3/H2O2
No Chemicals
O3/AC
Ozonation
Fenton Ultrasound
UV/TiO2
H2O+Ultrasound OH +H
H2O + VUV(120-160nm) OH +H
2O3 + HO2- 2OH +3O2
O3 + AC OH + O2
O3 + (OH-, NOM) OH
H2O2 + UVC 2 OH (F = 1)
O3+UVC H2O2 OH+O2
TiO2 + hn h+ + e- OH + O2-
Vacuum UV (VUV)
OH- yield: 50%
[Jarocki et al., in prep.]
H2O2
Fe(II) Fe(III)
OH
H2O2 HO2
[Fe(III)HO2]2+
Also direct
photolysis
pH < 4
BrO3-
NDMA
Comparison of Advanced Oxidative
Processes
UV based Ozone based H2O2 based
UV/H2O2(TiO2)
UV/O3
O3/H2O2
No Chemicals
O3/AC
Ozonation
Fenton Ultrasound
Energy demand
Vacuum UV
Loss of oxidation efficiency via matrix scavenging, assimilable organic carbon
formation, unknown transformation products
Negative Effects
Br- HOBr/OBr-
BrO3-
O3
O3/•OH
H2O2
Br-
Describing Pollutant Removal
Oxidant
No. of publ.
kinetic const.
k (ca. 2008)
Ozone ~ 500
OH Radicals ~ 2000
Chlorine ~ 300
Chlorodioxide ~ 100
Ferrate(VI) ~ 50
)
d Pk ox P
dt =
)0
lnP
k ox tP
=
Typical second order kinetic
constants for a pollutant P:
pH, T!
Quantification oxidant exposure:
• Matrix dependent
• Dosage dependent
• Consideration of secondary oxidants
Determination kinetic constants:
• Direct measurements
• Indirect measurements (Competition kinetics)
• Quantitative structure activity relationships (QSARs)
• Estimation from similar oxidants
Modified after U. von Gunten, eawag
Mechanistic Investigations
Degradation of Micropollutants:
Example Diclofenac
N
HOOCCl
Cl
H
O3
N
HOOCCl
Cl
H
O3
Possible sites of ozone attack
Diclofenac (Non-Steroidal Anti-Inflammatory Drug)
Ref.: Sein et al. (2008), Environ. Sci. Technol. 42, 6656
Degradation of Micropollutants:
Example Diclofenac
Ref.: Sein et al. (2008), Environ. Sci. Technol. 42, 6656
CH2
C O OH
N
Cl
Cl
H
O
O
O
CH2
C O OH
N
Cl
Cl
H
O3
CH2
C O OH
N
Cl
Cl
- O3
- H+
.
O3 + H2O OH + O2 + OH
([Diclofenac]0 = 50 µM) ■ Diclofenac ■ Iminoquinone (major intermediate) ■ 2,6-Dichloroaniline
0
5
10
15
20
25
30
35
40
45
50
0 50 100 150 200 250
[Ozone] / µM
[Dic
lofe
na
c]
an
d [
Pro
du
cts
] / µ
M
N
O
Cl
Cl
CH2
COOH
Ref.: Sein et al. (2008), Environ. Sci. Technol. 42, 6656
Diclofenac Degradation in Presence of t-BuOH
Suggested Reaction Mechanism for the
Formation of the Iminoquinone Intermediate
CH2
N
Cl
Cl
.CO2H
O3 / - O2
CH2
N
Cl
Cl.
CO2H
OH
CH2
N
Cl
Cl.
CO2H
HO
CH2
N
Cl
Cl.
CO2H
O2
HOOO
- HO2
CH2
N
Cl
Cl
CO2H
O
1,2 H-shift
Iminoquinone
Ref.: Sein et al. (2008), Environ. Sci. Technol. 42, 6656
Pilot-Scale Study
• Provides drinking water for ca. 80% of the
population of Luxemburg
• The drinking water treatment plant was
build up in 1969
• Modernization of treatment and increase
of water production to 100’000 m3/d
planned
SEBES
Surface area: 3,8 km2 Capacity: 60 Mill. m3
SEBES Syndicat des Eaux du Barrage
d'Esch-sur-Sûre
Raw Water
Postozonation
pH Adjustment/Flocculation
Membrane Filtration
Preozonation
pH Adjustment/Flocculation
Membrane Filtration
Biological Filtration
Simplified Scheme of the Pilot Plant
Pilot Study SEBES
Accompanying Lab Studies:
Ozone Scavenging
Ozone half life time vs. ozone dose preozonation (RW O3), postozonation (UF O3) and AOP O3/H2O2 (UF AOP)
206
402
573
701
26
230260
523
63 57 58 46
0
100
200
300
400
500
600
700
800
1 2 3 5
t[s]
c(O3) [mg/l]
RW O3
UF O3
UF AOP
0
0,005
0,01
0,015
0,02
0,025
0,03
1 2 3 4 5
Ozo
ne e
xp
osu
re [
M×
s]
c(O3) [mg/L]
RW O3
UF O3
UF AOP
Accompanying Lab Studies:
Disinfection Efficiency
Ozone exposure vs. ozone dose; preozonation (RW O3), postozonation (UF O3) and AOP O3/H2O2 (UF AOP); reaction time 500 s, DOC: raw water 2 mg/L, UF filtrate 1 mg/L, alkalinity: 0.4 mM, pH: 7
99% inactivation
B. subtilis spores
Accompanying Lab Studies:
Bromate Formation Potential
Bromate formation vs. ozone dose, c(Br-): 20 µg/L, complete ozone depletion, preozonation (RW O3), postozonation (UF O3) and AOP O3/H2O2 (UF AOP), DOC: RW 2 mg/L, UF 1 mg/L, Alkalinity: 0.4 mM, pH: 7
Bromate TLV
0
5
10
15
20
25
1 2 3 5
c(B
rO3
- )[µ
g/l]
c(O3) [mg/l]
RW O3
UF O3
UF AOP
Bromate drinking water standard
Design of Postozonation
Design of Postozonation
PN 2
PN 3
PN 1
H2O2
Q = 1 m3/h
c(O3) = 1, 3, 5 mg/L
c(H2O2) = ca. c(O3)
Reaction time = 10 min
0102030405060708090
100
Raw water Flocculation/UF UF O3 AC filter
Re
sid
ua
l c
on
c. in
%Pilot: Micropollutant Elimination
Bentazone MTBE
Dichlorobenzamide
Diclofenac
Carbamazepine
Sulfadiazine
Ozon dose UF O3 1 mg/L O3, PN 3
kO3: < 10, 700, > 103 M-1s-1
Pilot: Micropollutant Elimination
0
0,2
0,4
0,6
0,8
1
1,2
1 2 3 4
Co
nc
en
tra
tio
n [
µg
/l]
Sampling point
No transformation of Chlorthalonil M12 by O3 or •OH
S OO
OH
NH2
O
Cl
ClCl
N
PN1 PN2 PN3 Complete ozone consumption
AOP O3/H2O2 , O3 4 mg/L, H2O2 17 mg/L DOC 1 mg/L, Alkalinity: 0.4 mM, pH: 7
Summary of Pilot Study
(Preozonation)
Intermediate disinfection
Intermediate oxidation efficiency
Bromate formation at high ozone doses
O3
Flocculation + UF
O3
(Postozonation)
Good disinfection
Lowered oxidation efficiency
Increased bromate formation
O3 + H2O2
(Post AOP)
Poor disinfection
High oxidation efficiency
Bromate formation can be controlled
Reservoir
Synergy via switch between two modi
Disinfection modus Oxidation modus
Full-Scale Implementation
45
Elimination of pharmaceutical residues in
municipal wastewater treatment plants
(WWTP: Schwerte, Bad Sassendorf & Duisburg-Vierlinden)
Institut für Siedlungswasserwirtschaft und Abfalltechnik
Lehrstuhl für Siedlungswasser- wirtschaft und Umwelttechnik
Abteilung für Hygiene, Sozial- und Umweltmedizin
Project management: Dr. Thomas Grünebaum (Ruhrverband, Essen)
Research projects „Reine Ruhr“
Final report: http://www.lanuv.nrw.de/wasser/abwasser/forschung/abwa
sser.htm
Elimination of Selected Target Compounds in Large Scale WWTP
2 mg Ozone/L, zspec = 0.36
0
10
20
30
40
50
60
70
80
90
100
Elim
inati
on
[%
]
n.d.
© Jochen Türk, IUTA
0
10
20
30
40
50
60
70
80
90
100
Elim
ina
tio
n [
%]
5 mg Ozone/L, zspec = 0.91
Take-home Messages
Oxidative Processes can be used to meet (additional)
goals of water and wastewater treatment
Optimized technical use requires a profound
understanding of chemistry of oxidant species
including formation of oxidation byproducts
For micropollutant elimination detailed knowledge of
transformation reaction is needed but enormous
effort needed
Comprehensive economical and effect-orientied
evaluations are still largely lacking
Acknowledgements
• Current and Previous Coworkers in Oxidative Processes: Alexandra Jarocki, Alexandra Beermann, Maike Cyris, Agnes Tekle-Rötering, Sebastian Kowal, Alaa Salma, Myint Sein, Clemens von Sonntag, Jochen Türk, numerous students
• Collaborators: Urs von Gunten, Georges Kraus, Jean-Paul Lickes, Stefan Panglisch, André Tatzel
• Funding: Deutsche Forschungsgemeinschaft, BMWi/AiF, BMBF, Deutsche Bundesstiftung Umwelt, Wasserchemische Gesellschaft, EU MC-ITN ATWARM
ANAKON 2011, Zürich Wasser 2012, Neu-Ulm
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