6/10/2015Disinfection applications 1 Oxidation Case Studies J(Hans) van Leeuwen

6/10/2015Disinfection applications 2 Introduction Summary and explanation Simple calculations Show some applications

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

6/10/2015Disinfection applications 4 INTEGRATION OF CHICK’s LAW Integrating for N, N=N o at t = 0 ln N/N 0 = -kt N/N 0 = e -kt

6/10/2015Disinfection applications 5 Watson’s Law C n t = constant Simplified: Ct = constant Applies only for a fixed rate of “kill” a certain organism a specific disinfectant

6/10/2015Disinfection applications 6 Example Ct value for ozone is 1.0 mgL -1 min. We could achieve that with 1 mg/L ozone residual for 1 minute Or: 0.4 mg/L for 2.5 minutes

6/10/2015Disinfection applications 7 Free – HOCl and OCl - Combined – NH 2 Cl, NHCl 2 Total = Free + combined CHLORINE RESIDUALS

6/10/2015Disinfection applications 8 CHLORINE REACTIONS WITH AMMONIA Cl 2 + H 2 O  HOCl + H + Cl - HOCl + NH 3  NH 2 Cl + HOH HOCl + 2NH 2 Cl  N 2 + 3H + Cl - + H 2 O Net reaction: 2 x 2 nd + 3 rd : 3 HOCl + 2 NH 3  N 2 + 3H + Cl - + 3H 2 O

6/10/2015Disinfection applications 9 CHLORINE REACTIONS WITH AMMONIA Cl 2 + H 2 O  HOCl + H + Cl - HOCl + NH 3  NH 2 Cl + HOH HOCl + 2NH 2 Cl  N 2 + 3H + Cl - + H 2 O Net reaction: 3 x 1 st + 2 x 2 nd + 3 rd : 3 Cl NH 3  N 2 + 6H + Cl -

6/10/2015Disinfection applications 10 MEASUREMENT OF CHLORINE (OR CHLORAMINES) DPD – pink color develops KI solution – I -1 oxidized to I, forms I 2 Color of DPD or I 2 can be measured, or I 2 titrated with FAS solution

6/10/2015Disinfection applications 11 Other oxidation reactions formation

6/10/2015Disinfection applications 12 DISINFECTION BYPRODUCTS THMs - CHX 3, e.g. CHCl 3 Chlorite and chlorate, ClO 2 - ClO 3 - Bromoform - CHBr 3 Bromate - BrO 3 -

6/10/2015Disinfection applications 13 ClO2 made from Sodium Chlorite Acidification of Chlorite 5 ClO H +  4 ClO H2O + Cl - Oxidation of Chlorite by Chlorine 2 NaClO 2 + Cl 2  2 NaCl + 2 ClO 2 Oxidation of Chlorite by Persulfate 2 NaClO 2 + Na 2 S 2 O 8  2 ClO Na 2 SO 4 From Sodium Hypochlorite and Sodium Chlorite NaOCl + 2 NaClO HCl  2 ClO NaCl + H 2 O Electrochemical oxidation of chlorite ClO 2-  ClO2 + e- Dry chlorine/chlorite (laboratory method) NaClO 2 + 1/2 Cl 2 --> ClO 2 + NaCl (solid)

6/10/2015Disinfection applications 14 OZONE PRODUCTION Electron bombardment UV irradiation at < 200  m Electrolytically

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6/10/2015Disinfection applications 22 Corona Discharges in Ozone Generation

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6/10/2015Disinfection applications 25 Large Ozone Generators

6/10/2015Disinfection applications 26 Toxicity of ozone to humans Ozone concentration ppm Exposure time (minutes)

6/10/2015Disinfection applications 27 COMPONENTS OF AN OZONATION SYSTEM

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6/10/2015Disinfection applications 29 BUBBLECOLUMNCONSTRUCTIONDETAILS

6/10/2015Disinfection applications m Deep Shaft OzonationSystem

6/10/2015Disinfection applications 32 Ozone Pre-ozonationDisinfection G Raw Water Screening Clarification Filtration A Distribution C Residual Disinfection

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6/10/2015Disinfection applications 36 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

6/10/2015Disinfection applications 37 Scarce Water Resources near Mines

6/10/2015Disinfection applications 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)

6/10/2015Disinfection applications 39 Mine Water Cooling

6/10/2015Disinfection applications 40 Case Study: Mining Application

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6/10/2015Disinfection applications 43 DUST

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6/10/2015Disinfection applications 46 POSSIBLE INHIBITORS High temperatures Heavy metals Disinfectant byproducts or residues

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6/10/2015Disinfection applications 48 Ozonation Bubble Column Sand Filters

6/10/2015Disinfection applications 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

6/10/2015Disinfection applications 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

6/10/2015Disinfection applications 51 CYANIDE REMOVAL FROM COG

6/10/2015Disinfection applications 52 CYANIDE REMOVAL FROM BHP

6/10/2015Disinfection applications 53 CYANATE REMOVAL FROM BHP

6/10/2015Disinfection applications 54 TOC AND COLOR REMOVAL FROM ACTIVATED SLUDGE EFFLUENT

6/10/2015Disinfection applications 55 Cost Implications: CN- Capital cost of ozone installation $ 0.64 million Amortisation, maintenance operation $16,000 per month Present alternative, formaldehyde costs $ 7000 per month, more COD Ozone not cost effective

6/10/2015Disinfection applications 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

6/10/2015Disinfection applications 57 SYNTHETIC ORGANIC REMOVAL BY INTEGRATED OZONOLYSIS / ACTIVATED SLUDGE

6/10/2015Disinfection applications 58 Air - CONVENTIONAL PREOZONATION + ACTIVATED SLUDGE

6/10/2015Disinfection applications 59 More Treatment required POST-OZONATION: Remove degradables first

6/10/2015Disinfection applications 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

6/10/2015Disinfection applications 61 Biological treatment before and after ozonation Ozonated Recycle Using a large ozonated recycle

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6/10/2015Disinfection applications 63 THE SOLUTION INVESTIGATED O 3

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6/10/2015Disinfection applications 65 Experimental Set-up Activated sludge with wastewater containing methylene blue  ozonated

6/10/2015Disinfection applications 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

6/10/2015Disinfection applications 67 Control after settling Ozonated mixed liquor

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6/10/2015Disinfection applications 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

6/10/2015Disinfection applications 71 Pilot Scale Implementation at Van Diest Supply Company, Iowa