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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