POTENTIAL AND LIMITATIONS OF (ADVANCED) OXIDATION PROCESSES IN WATER AND WASTEWATER TREATMENT

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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

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

Relative EE2 or EEEQ

0.0 0.2 0.4 0.6 0.8 1.0

Relative EE2

0.0 0.2 0.4 0.6 0.8 1.0

Relative EEEQ

0.0 0.2 0.4 0.6 0.8 1.0

Chlorine

dose, M

0 5 10 15 20 25 30

Bromine

Relative EE2

0.0 0.2 0.4 0.6 0.8 1.0

Relative EEEQ

0.0 0.2 0.4 0.6 0.8 1.0

dose, M

0 5 10 15 20 25 30

Ozone

Relative EE2

0.0 0.2 0.4 0.6 0.8 1.0

Relative EEEQ

0.0 0.2 0.4 0.6 0.8 1.0

UV fluence, mJ/cm²

0 100 200 300 400

0.0 0.2 0.4 0.6 0.8 1.0

OH radical

Relative EE2

0.0 0.2 0.4 0.6 0.8 1.0

Relative EEEQ

0.0 0.2 0.4 0.6 0.8 1.0

dose, M

0 5 10 15 20 25 30

Chlorine dioxide

Relative EE2

0.0 0.2 0.4 0.6 0.8 1.0

Relative EEEQ

0.0 0.2 0.4 0.6 0.8 1.0

dose, M

0 10 20 30 40

Ferrate

Relative EE2

0.0 0.2 0.4 0.6 0.8 1.0

Relative EEEQ

0.0 0.2 0.4 0.6 0.8 1.0

1

r² = 0.96 r² = 0.99

1 1

r² = 0.99

1 r² = 0.99

1 r² = 0.99

1 r² = 0.99

Relative EE2 or EEEQ

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^-  2^OH +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 P k ox P

 dt =   

       )

0

ln P

k ox t

P =    

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

HOOC Cl

Cl H

O₃

N

HOOC Cl

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

O

CH₂ O C OH

N

Cl

Cl

- O₃^{ }

- H⁺

.

O

+ H

O 

OH + O

+ 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

[Diclofenac] and [Products] / µM

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

.

CO₂H

O H

CH₂ N

Cl

Cl

.

CO₂H

HO

CH₂ N

Cl

.

CO₂H

O₂

HO O O - 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

230 260

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

Ozone exposure [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(BrO3- )[µg/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

H

O

Q = 1 m

/h

c(O

) = 1, 3, 5 mg/L

c(H

O

) = ca. c(O

)

Reaction time = 10 min

0 10 20 30 40 50 60 70 80 90 100

Raw water Flocculation/UF UF O3 AC filter

Residual conc. in %

Pilot: Micropollutant Elimination

Bentazone MTBE

Dichlorobenzamide

Diclofenac Carbamazepine

Sulfadiazine

Ozon dose UF O₃ 1mg/L O₃, PN 3

k_O3: < 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

Concentration [µg/l]

Sampling point

No transformation of Chlorthalonil M12 by O₃ or ^•OH

S O

O

OH

N H₂

O

Cl

Cl Cl

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

O

Flocculation + UF

O

(Postozonation)

Good disinfection

Lowered oxidation efficiency

Increased bromate formation

O

+ H

O

(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, z_spec = 0.36

0 10 20 30 40 50 60 70 80 90 100

Elimination [%]

n.d.

© Jochen Türk, IUTA

0 10 20 30 40 50 60 70 80 90 100

Elimination [%]

5 mg Ozone/L, z_spec = 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