oxidative treatment of trace organic contaminants in ... · envirowater, 2-4 march 2009 oxidative...

EnviroWater, 2-4 March 2009

Oxidative Treatment of Trace Organic Oxidative Treatment of Trace Organic Contaminants in Wastewater Effluents Contaminants in Wastewater Effluents

by Oby O33 and Oand O33/H/H22OO22

Myint Myint Sein*, Alexandra Jarocki*, Torsten C. Schmidt*, Alfred Golloch*,

Clemens von Sonntag**

*University of Duisburg-Essen, Instrumental Analytical Chemistry, Lotharstr. 1, 47057 Duisburg, Germany

**Max Planck Institute for Bioinorganic Chemistry, Stiftstr. 34-36, 45413 Mülheim an der Ruhr, Germany


OutlineOutline

• IntroductionOxidation processes (Direct ozonation,

Radical reaction)• Objective• Experimental• Results• Conclusion


• Modern wastewater treatment plants are very effective, but traces of organic pollutants are still detected

• In order to protect the environment these organic pollutants must be removed

• One of the most promising techniques to solve the problem is the treatment of the wastewater effluents by ozonation

IntroductionIntroduction

OxidationOxidation ProcessesProcessesUse of Ozone:

DisinfectionOxidation of organic micropollutants

Two possible pathways during ozonation:Oxidation by direct ozone

(olefins, amines, phenols, aromatics with ē donors)Oxidation by free .OH Radicals

1.36Chlorine Cl2

1.79HydrogenperoxideH2O2

2.07Ozone O3

2.42Oxygenradical ·O

2.79Hydroxylradicals ·OH

Oxidation Potential

(V)

OxidantSpecies

Mox Direct reaction(kO3 = 10-3 – 109 M-1 s-1)

+ M

OH-·OH

+ M M'ox Radical reaction(k·OH = 108 – 1010 M-1 s-1)

O3

At higher pH

These reaction pathways take place simultaneously.

Limitations of Use of OzoneLimitations of Use of Ozone• Some organic compounds are refractory towards ozone attack• High energy demand and the handling• Formation of BrO3

- (max. allowed limit 10 µg/L in drinking water)

To overcome these drawback, ozonation process alone is beingmodified to increase the oxidising capability

Advanced Oxidation Process (AOP)

e.g, Oxidation by H2O2 + O3 (Peroxone process)H2O2 + 2 O3 → 2 .OH + 3 O2

AOP has become an attractive and increasingly important research field in theuse of ozone


• To investigate the removal efficiency of the selected trace organic substances in wastewater effluent by treating with O3 and H2O2 + O3

ObjectiveObjective

Selected Organic Trace Pollutants in Selected Organic Trace Pollutants in Wastewater EffluentsWastewater Effluents

Commonly used pain killer.86 t a-1 in Germany (2003)

Diclofenac(non-steroidal anti-inflammatory drug)

Fungicides (in wood, textiles, paints)Endocrine disruptorsIn the category 1 in the priority list of compounds. No longer allowed since 1993 in Europe

Tri-n-butyltin chloride(Organotin compounds)

Mainly used as a plasticizer, an additive in the clothing industry

Tri n-butylphosphate (TnBP)

Used as a flame retardant,applied in insulation for buildings and in refrigerator casings

Tris-(1-chloro-2-propyl)-phosphate (TCPP)

Applied in doses up to 200 g per Person.The global consumption is ~3500 t a-1.Rapidly excreted unchanged

Iopamidol(X-ray contrast medium)

UsesSubstance

The Reaction Rate Constants of these The Reaction Rate Constants of these Selected Organic Trace PollutantsSelected Organic Trace Pollutants

-< 1Tris-(1-chloro-2-propyl)-phosphate (TCPP)

(5)

2.8 x 1091.4Iopamidol(3)

~ 0.013

7 - 10

6.3 x 105

kO3 (M-1 s-1)

1 x 1010Tributylphosphate (TnBP)(4)

-Tributyltin Chloride(2)

7.5 x 109Diclofenac(1)

k·OH (M-1 s-1)Substances

8.5 x 106

3.9 x 108

<<1 x 10-2

<1 x 10-2-HCO3

- (Radical

-CO32- scavengers)

mg /mg DOC0

mg /mg DOC0

Oxidation

212

211

(AOP)Dose of H2O2

(Pure ozonation) Z spec.

ExperimentalExperimental

GO3 = the gas ozone concentration (mg/LG)Q = the gas flow rate (L/min)t = the reaction time (min)DO3 = the dissolved ozone concentration (mg/Lw)V = the water volume treated (L)DOC = dissolved organic carbon (mg/L)

The spec. ozone consumption:Zspec. (mg/ mg) = [ ∫ (GO3, gas in – GO3, gas out) Q x dt – (DO3 x V)] / DOC

The Continuous Ozone ReactionThe Continuous Ozone Reaction of Spiked of Spiked Wastewater EffluentWastewater Effluent

O2

O3 generator

O3 inlet

O3 outlet

O3 analyzer

Reactor

H2O2 solution

45 L

˚°° ˚˚ ˚°

Sample collector

Wastewater effluent

150 L/hr

150 L/hr

Organic compound

pH 8

Ozone Ozone Decomposition in Water Decomposition in Water

Before ozonation

After ozonation

Ozone decomposes rapidly in water

- High pH, high Temp.- high DOC

*(t½ : ≤ 0.35 s at DOC 8.5 mg/L;~ 0.5 s at DOC 4.5 µg/L)

[O3]0 = 4 mg/L

* Buffle et al., Water Research, 40(9), 1884, 2006.


Diclofenac Diclofenac ((NonNon--SteroidalSteroidal AntiAnti--InflammatoryInflammatory Drug)Drug)

N

HOOCCl

Cl

HO3

N

HOOCCl

Cl

H

O3

Possible sites of ozone attack

ResultsResults

Elimination of diclofenac from wastewater effluent by Ozone(C0 = 10 mg/L, DOC = 10 ppm, pH = 8)

7.5 x 109

K˙OH (M-1 s-1)6.3 x 105Diclofenac

kO3 (M-1 s-1)

11

96 100

0

10

2030

40

50

60

7080

90

100

0.5 1.0 1.5

[O3] mg/ DOC

Elim

inat

ion

(%)

Well eliminated by ozone direct reaction or/and radical type reaction.O3 dose 1 mg/ DOC eliminates > 90% diclofenac.

0

5

10

15

20

25

30

35

40

45

50

0 50 100 150 200 250

[Ozone] / µM

[Dic

lofe

nac]

and

[Pro

duct

s] /

µM

(■ Diclofenac ■ Iminoquinone (major intermediate) ■ 2,6-Dichloroaniline)

N

O

Cl

Cl

CH2

COOH

N

O

Cl

Cl

CH2

COOH

H2N

C l

C l

C H 2

CO O H

N

C l

C l

H

O3 / ·OH

M. M. Sein et al., Oxidation of diclofenac by ozone, Environ. Sci. Technol, 42(17), 6656, 2008.

Main Degradation Pathway of Diclofenac during Ozonation

Sufficient amt. of ozone is needed to eliminate diclofenac and its OPs

O3 / ·OH


TriTri--nn--butyltinbutyltin Chloride Chloride

nn--butyltinbutyltin compounds, (Bucompounds, (Bu(4(4--n)n)--SnSn--XXn n )) (n=1,2,3), (n=1,2,3), (X= Cl, Br, I)

Toxicity(Bu)3-Sn-X >>> (Bu)2-Sn-X2 >> Bu-Sn-X3

(TBT) (DBT) (MBT)

Elimination of TBTCl from wastewater effluent by ozone and ozone + H2O2, (C0 = 100 µg/L; DOC = 10 ppm, pH = 8)

-

K˙OH (M-1 s-1)

DBT, MBT7.2 - 10TBT chloride

Reaction productskO3 (M-1 s-1)

In pure ozonation, the main reaction pathway must be the radical reaction.~ 80% TBTCl can be eliminated by 1 mg O3/DOC. Higher O3 dose can increase the elimination efficiency, > 90%.

Elimination of TBTCl 100 µg/L

7679

8896 96 94

0

20

40

60

80

100

120

without H2O2 1 mg H2O2/DOC 2 mg H2O2/DOC

Elim

inat

ion

(%)

1 mg O3 / DOC 2 mg O3 / DOC


IopamidolIopamidol((XX--Ray Contrast Medium)Ray Contrast Medium)

Elimination of iopamidol from wastewater effluent by ozone and ozone + H2O2; (C0 = 200 µg/L; DOC = 10 ppm, pH = 8)

2.8 x 109

K˙OH (M-1 s-1)

1.4Iopamidol

kO3 (M-1 s-1)

Elimination of iopamidol (200 µg/L)

56

74 77

94100 97

0

20

40

60

80

100

w ithout H2O2 0.5 mg H2O2/DOC 1 mg H2O2/DOC

Elim

inat

ion

(%)

1 mg/L O3 2 mg/L O3

The main reaction pathway must be by radical reaction.Elimination efficiency can be increased by higher O3 dose >90%. Addition of H2O2 does not much enhance the elimination efficiency.


OrganophosphatesOrganophosphates

POO

OO

Tri-n-butylphosphateTnBP

CH3CCH2Cl

HOPO OO

CCH3

CH2ClH

CH3C CH2ClH

Tris-2-chloroisopropylphosphateTCPP

CHH

CH

HCH

HCH3

CHH

C

CH

HCH

HCH3

H

HCH

HCH

HH3C

8

52

42

7270

71

0

20

40

60

80

100


Elim

inat

ion

(%)

1 mg O3 / DOC2 mg O3 / DOC

50

929998 99 99

0

20

40

60

80

100


Elim

inat

ion

(%)

1 mg O3 / DOC2 mg O3/ DOC

Elimination of TnBP (left) and TCPP (right) from wastewater effluent by ozone and ozone + H2O2

(C0 = 25 µg/L; DOC = 10 ppm, pH = 8)

-< 1TCPP1 x 10100.8TnBP

K˙OH (M-1 s-1)kO3 (M-1 s-1)

The main reaction pathway must be by radical reaction.Elimination efficiency is improved by higher O3 dose.The addition of H2O2 can enhance the elimination to a some extent.

Formation of Formation of BromateBromate during Ozone Reactionduring Ozone Reaction

Influence of Br- concentration in the formation of BrO3

- during ozonation of wastewater effluent(DOC = 14.2 mg/L, TIC = 45 mg/L, pH = 8, T = 20°C)(Schumacher, J., PhD Dissertation, Berlin, 2006).

y = 0,0854x - 6,5342

y = 0,3239x + 3,8618

0

20

40

60

80

100

120

140

0 50 100 150 200 250 300 350 400

Bromide [µg/L]

Bro

mat

e [µ

g/L]

O3 ini = 10 mg/LO3 ini = 20 mg/L

Bromate formation during ozonation of wastewater effluent (DOC = 11.1 mg/L, [Br-]0 = 110 µg/L)(Nöthe, T., PhD Dissertation, Dortmund, 2009).

-100

10203040506070

0 0,5 1 1,5 2

Zspec

[Bro

mat

e] /

µg L

-1

Zspec = 0.8 (9 mg/L O3)

Zspec = 0.91 (10 mg/L O3)

BrO3- formation depends on:

- pH- DOC- Initial Br-

- O3 exposure


Dosing of NH3/ NH4+ can reduce 40% of BrO3

- formation.

Br- + O3 → BrO- + O2 → → → BrO3-

BrO- + NH3 → H2NBr + OH-

To Control the BrO3- Formation


ConclusionConclusion• Oxidation by O3 turned out to be a promising approach

for treatment of wastewater effluents. • At higher pH, O3 decomposes into ·OH and thus a

concentration reduction of the organic pollutants is achieved.

• Ozonation of wastewater effluent can be applied in practice(Total cost 5 cent/m3 at Zspec = 2 mg/mg DOC0)

• In pure ozonation, the elimination depends on the O3concentration.

• Addition of H2O2 (AOP) enhances the elimination only to some extent.


AcknowledgementAcknowledgement

Federal Ministry of Education and Research

Bundesministerium für Bildungund Forschung (BMBF)


Thank you for your attention

oxidative treatment of trace organic contaminants in ... · envirowater, 2-4 march 2009 oxidative...

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