1. Oxidation Case Studies
J(Hans) van Leeuwen
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Disinfection applications

2. Introduction Summary and explanation Simple calculations
Show some applications
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3. DISINFECTION KINETICS
Chick’s Law
dN = -kN dt
N is the number of microorganisms at time t,
and k is a constant (dimension : t-1).
This constant applies only for a fixed
concentration of a certain disinfectant

4. N/N0 = e-kt INTEGRATION OF CHICK’s LAW
Integrating for N, N=No at t = 0
ln N/N0 = -kt
N/N0 = e-kt
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5. Watson’s Law Cnt = constant Ct = constant Applies only for
Simplified:
Ct = constant
Applies only for
a fixed rate of “kill”
a certain organism
a specific disinfectant
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6. Example Ct value for ozone is 1.0 mgL-1min. We could achieve that with
1 mg/L ozone residual for 1 minute
Or: 0.4 mg/L for 2.5 minutes
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7. Free – HOCl and OCl- Combined – NH2Cl, NHCl2 Total = Free + combined
CHLORINE RESIDUALS
Free – HOCl and OCl-
Combined – NH2Cl, NHCl2
Total = Free + combined
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8. CHLORINE REACTIONS WITH AMMONIA
Cl2 + H2O  HOCl + H+Cl-
HOCl + NH3  NH2Cl + HOH
HOCl + 2NH2Cl  N H+Cl- + H2O
Net reaction: 2 x 2nd + 3rd :
3 HOCl + 2 NH3  N H+Cl- + 3H2O
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9. CHLORINE REACTIONS WITH AMMONIA
Cl2 + H2O  HOCl + H+Cl-
HOCl + NH3  NH2Cl + HOH
HOCl + 2NH2Cl  N H+Cl- + H2O
Net reaction: 3 x 1st x 2nd + 3rd :
3 Cl NH3  N H+Cl-
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10. MEASUREMENT OF CHLORINE (OR CHLORAMINES)
DPD – pink color develops
KI solution – I-1 oxidized to I, forms I2
Color of DPD or I2 can be measured,
or I2 titrated with FAS solution
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11. Other oxidation reactions
formation
Other oxidation reactions
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12. DISINFECTION BYPRODUCTS THMs - CHX3, e.g. CHCl3 Chlorite and chlorate,
ClO ClO3-
Bromoform - CHBr3
Bromate - BrO3-
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13. ClO2 made from Sodium Chlorite
Acidification of Chlorite 5 ClO H+  4 ClO2 + 2 H2O + Cl-
Oxidation of Chlorite by Chlorine 2 NaClO2 + Cl2  2 NaCl + 2 ClO2
Oxidation of Chlorite by Persulfate 2 NaClO2 + Na2S2O8  2 ClO2 + 2 Na2SO4
From Sodium Hypochlorite and Sodium Chlorite NaOCl + 2 NaClO2 + 2 HCl  2 ClO2 + 3 NaCl + H2O
Electrochemical oxidation of chlorite ClO2-  ClO2 + e-
Dry chlorine/chlorite (laboratory method) NaClO2 + 1/2 Cl2 --> ClO2 + NaCl (solid)
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14. OZONE PRODUCTION Electron bombardment UV irradiation at < 200 m
Electrolytically
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22. Corona Discharges in Ozone Generation
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25. Large Ozone Generators
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26. Toxicity of ozone to humans
Ozone concentration ppm
Exposure time (minutes)
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27. COMPONENTS OF AN OZONATION SYSTEM
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29. BUBBLE COLUMN CONSTRUCTION DETAILS 11/27/2018
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30. Deep Shaft Ozonation System 50m 50 m 11/27/2018
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32. Ozone Pre-ozonation Disinfection G Raw Water A C Residual Disinfection
Screening
Clarification
Filtration A
Distribution C
Residual
Disinfection
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36. Cyanotoxins – cylindrospermopsin, microcystin, anatoxin*
OTHER USES OF OZONE
IN WATER TREATMENT
Iron and Mn removal
Color removal
Geosmin and 2-MIB
Cyanotoxins – cylindrospermopsin, microcystin, anatoxin*
Microflocculation
Biodegradability
*Produced by Cylindrospermopsis, Microcystis and Anabena genera
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37. Scarce Water Resources near Mines
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38. Further Applications of Ozone in The Water Technology Field
Wastewater treatment
Effluent disinfection
Cooling water treatment
Swimming pools
Ozonated ice
Ozonated air
AOP (advanced oxidation processes)
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39. Mine Water Cooling
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40. Case Study: Mining Application
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43. DUST
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46. POSSIBLE INHIBITORS High temperatures Heavy metals
Disinfectant byproducts
or residues
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48. Ozonation Bubble Column
Sand Filters
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49. Oxidation of cyanides, thiocyanate and TOC in the Reclamation of Water in Steel Processing
BHP near Wollongong, Australia reuses wastewater after biological and activated carbon treatment
Cyanides interfere with biological treatment and need to be lowered to 200 mg/L before activated sludge
Cyanates are incompletely removed if over 250 mg/L
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50. BHP Ozonation Investigations
Ozone was tested to observe efficacy to remove CN- and SCN-
Ozone requirements due to competitive reactions observed
Ozone needs to replace or enhance activated carbon treatment
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51. CYANIDE REMOVAL FROM COG
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52. CYANIDE REMOVAL FROM BHP
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53. CYANATE REMOVAL FROM BHP
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54. TOC AND COLOR REMOVAL FROM ACTIVATED SLUDGE EFFLUENT
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55. Cost Implications: CN-
Capital cost of ozone installation $ million
Amortisation, maintenance operation $16,000 per month
Present alternative, formaldehyde costs $ 7000 per month, more COD
Ozone not cost effective
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56. Cost implications: SCN-
Capital required $ 2.0 million
Monthly costs $
No other method SCN- removal There will be a much smaller risk in achieving treatment objectives
Ozone not economical
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57. SYNTHETIC ORGANIC REMOVAL BY INTEGRATED OZONOLYSIS/ ACTIVATED SLUDGE
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58. - Air Air CONVENTIONAL PREOZONATION + ACTIVATED SLUDGE 11/27/2018
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59. POST-OZONATION: Remove degradables first
More
Treatment
required
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60. Since ozonolysis results in biodegradable byproducts,
more biological treatment
required after post-ozonation
This requirement can be resolved
in two possible ways:
¶ another biological treatment stage
¶ recirculation to biological treatment
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61. Biological treatment before and after ozonation Using a large ozonated
recycle
Ozonated Recycle
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63. THE SOLUTION INVESTIGATED
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65. Experimental Set-up Activated sludge with wastewater
containing methylene blue
 ozonated
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66. Results  MeBl removal in ozonated activated sludge 95%
vs. 40% in control
COD removal in ozonated
activated sludge 80.5%
vs. 79.5% in control
 Better biomass settling
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67. Control Ozonated after settling mixed liquor 11/27/2018
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70. Conclusions
 Ozone can be dosed within an activated sludge system for the ozonolysis of non-biodegradables
 Effect on biomass beneficial, if minimal
 Byproducts mainly biodegradable
 Economical integrated procedure
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71. Pilot Scale Implementation at Van Diest Supply Company, Iowa
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