4 What Ozone Does Not DoOzone is incapable of oxidizing radon, methane, and nitratesBelow pH of 9, ozone is incapable of oxidizing ammonia at any practical rateOzone can not practically oxidize any of the trihalomethanes except very slowly
5 What Ozone Does Not DoOzone can not oxidize chloride ion to produce free chlorine at any practical rateOzone cannot oxidize calcium, magnesium, carbonate, or bicarbonate ions; consequently, ozone can not treat hardness or alkalinity
7 What Ozone Does Well Disinfection Ozone kills bacteria, viruses, spores and cysts through a process called cellular lysis - an oxidation process in which ozone ruptures the cellular membrane of the micro-organisms and disperses the cytoplasm into solution.With bacteria such as E. Coli, streptococcus fecalis, and legionella pneumophila relatively low doses of ozone are required and inactivation occurs up to 3,125 times faster than chlorine.
8 What Ozone Does Well Disinfection: A 3-log (99.9%) reduction of viruses can be easily achieved with significantly lower CT values than for chlorine.Spores and cysts such as Giardia and Cryptosporidium can be inactivated with relatively high dosages of ozone. Crypto requires increasingly higher dosages of ozone for inactivation, currently with CT values 5 times that of Giardia. There is no established CT value for Cryptosporidium inactivation with chlorine.
9 What Ozone Does Well Taste and Odor Control Algae Control Ozone oxidizes the organics such as tannins, unsaturated aldehydes, humic and fulvic acids, etc. responsible for 90% of taste and odor problems.Algae ControlOzone effectively kills plankton by oxidizing essential organic compounds that are part of the metabollic process.
10 What Ozone Does Well Oxidation Pre-oxidation Ozone’s powerful oxidation potential can remove a variety of man-made organic compounds including pesticides, VOCs, SOCs, and other micro pollutants.Pre-oxidationOzone’s powerful oxidation potential can precipitate dissolved iron, manganese, and sulfide faster than any other commonly used oxidants, aiding removal by direct filtration
11 Benefits of Ozone Generated on site More powerful than chlorine No transportation or storage required.More powerful than chlorine100 times the oxidizing power of chlorine without the handling problemsReverts to oxygen leaving no telltale taste or odor to be removedGreatly simplifies water chemistry and control.
13 Mass Transfer BasicsMass transfer is the movement of molecules of a substance to and across an interface from one phase to another.i.e.: the amount of ozone that transfers from air, across the air-water interface and into water.
14 Mass Transfer Basics Factors affecting transfer of gas into liquid: Pressure: as pressure increases, more gas is forced into liquid.Temperature of the water/gas mixture: at lower temperatures, ozone gas is more easily absorbed into liquid. At higher temperatures, water tries to release gas rather than absorb it.
15 Mass Transfer Basics:Factors affecting the transfer of gas into liquid:Bubble size: as a gas is broken down into more and more smaller bubbles, the total surface area of the bubbles increase, thus increasing the surface area for interaction of ozone and water.Concentration of ozone in the carrier gas: at higher ozone concentration in the carrier gas, higher amounts of ozone are absorbed into the water.
16 Mass Transfer Basics Concentration of ozone in the carrier gas: Ultra violet ozone generators- 0.01% to 0.10% concentration by weight (0.10% concentration = 1,000 ppm)Corona discharge ozone generators- 1.0% to 6.0% concentration by weight (1.0% concentration = 10,000 ppm)The concentration of ozone gas is determined at a standard temperature of 68º F (20º C) and standard pressure of 1 atmosphere (14.7 psi).
17 Mass Transfer Basics Concentration of ozone in the carrier gas: At the same percentage of mass transfer efficiency, a CD ozone generator will deliver more ozone to the water than an UV ozone generator.Ozone concentration directly affects it’s ability to become soluble in water.
18 Mass Transfer BasicsConcentration of ozone in the carrier gas:
19 Aeration vs. Venturi Injection Bubble diffusionPressure in the system created by water column - relatively low pressuresTaller tanks will increase system pressure.Large bubble size - smaller total surface area for ozone and water interface to occurDiffusion devices with smaller pore sizes are more likely to clog.Mass transfer efficiencies up to 75%, typically around 50%.
20 Aeration vs. Venturi Injection Differential pressure venturi injector technology utilizes water flow to create a vacuum to pull ozone gas into water.A turbulent interaction of the ozone gas and water occurs at the throat of the injector as the gas/water stream compresses, expands, and recompresses rapidly creating cavitation.Very fine bubbles are created allowing more total surface area for ozone and water interface to occur.
21 Aeration vs. Venturi Injection The back pressure at the outlet of the injector allows higher levels of ozone to dissolve into solution.Typically requires a 20 psi pressure differential.When properly sized, up to 99% mass transfer efficiencies can be achieved.Mazzei venturi sizing?
27 Commercial Water Treatment Water sourceWell water - generally very good quality; ozone used for pre-oxidation of dissolved metals including iron, manganese, and sulfides into filterable precipitateWells with surface water intrusion - generally very good quality; ozone used for pre-oxidation of dissolved metals into filterable precipitate and disinfection, typically coliform bacteriaSurface water - varying water quality; ozone used for primary disinfection, color, taste, and odor removal
28 Commercial Water Treatment DisinfectionIndependent of pH.Spores and cysts including Giardia, Cryptosporidium, etc. - sizing based on CT values, typically requires high dosagesCurrently, the EPA recognizes ozone as the only oxidant capable of Cryptosporidium inactivation - CT values 5 times that of GiardiaBacteria and viruses including coliform bacteria, E. Coli, Legionella, etc. - applied dosage of 1.5 mg/l recommended
29 Commercial Water Treatment Disinfection: the C.T. value conceptC = the residual concentration of the disinfectant in mg/L measured at or before the first point of consumptionT = the contact time required (in minutes) for water to travel from the point of injection to the point where C is measured the residualFor example: A 0.4 disinfection residual after a 4 minute contact time (.4 x 4 = 1.6) will yield a CT value of 1.6.
30 CT Values for Giardia Cyst Inactivation by Ozone: At various water temperatures - pH can be anywhere between 6 and 8 (Source: EPA, SWTR GuidanceManual,October, 1990)Removal 0.5°C 5°C 10°C 15°C 20°C 25°C 33°F 41°F 50°F 59°F 68°F 77°F0.5 log1.0 log1.5 log2.0 log2.5 log3.0 logCT Values for Giardia Cyst Inactivation by Free Chlorine:Water temperature at 20˚C (68˚F) at various pH readingsRemoval < <9.00.6 log1.0 log1.6 log2.0 log2.6 log3.0 log
31 Commercial Water Oxidation Best at pH over 7. Man-made organic compounds including pesticides, VOCs, SOCs, and other micro pollutants - applied dosage of 0.5 to 5.0 mg/l recommendedTannins, unsaturated aldehydes, humic and fulvic acids, etc. responsible for 90% of taste and odor problems - applied dosage of 1.5 mg/l recommended
32 Commercial Water Treatment Pre-oxidation: IronDivalent ferrous iron (Fe2+) oxidizes to trivalent ferric iron (Fe3+), which precipitates as ferric hydroxide.Rapid reaction.Best at pH over 7, preferably over 7.5.Theoretical applied ozone dosage to oxidize 1 mg/l of iron is 0.43 mg/lIf complexed with organics, recommend doubling the applied ozone dosage and increasing contact time.
33 Commercial Water Treatment Pre-oxidation: SulfideHydrogen sulfide ion is oxidized to soluble sulfate ion and in-soluble elemental sulfur.Rapid reaction.Independent of pH.Theoretical applied ozone dosage to oxidize 1 mg/l of sulfide ion is 1.5 mg/lIf complexed with organics, recommend doubling the applied ozone dosage and increasing contact time.
34 Commercial Water Treatment Pre-oxidation: ManganeseDivalent manganese (Mn2+) oxidizes to tetravalent manganese (Mn4+), hydrolyzing to insoluble managanese oxyhydroxide.Optimum between pH range ofTheoretical applied ozone dosage to oxidize 1 mg/l of manganese is 0.88 mg/l.Over oxidation will produce soluble permanganate ion indicated by pink water.
35 Commercial Water Treatment Sizing an ozone systemBased upon the amount of ozone required to completely react with the contaminants being treated in the water.Disinfection: spores and cysts - sizing based on CT valuesDisinfection: bacteria and viruses mg/l applied ozone dosageOxidation: VOCs and SOCs to 5.0 mg/l applied dosageOxidation: tannins mg/l applied dosagePre-oxidation: iron mg/l applied dosagePre-oxidation: sulfide mg/l applied dosagePre-oxidation: manganese mg/l applied dosage
36 Commercial Water Treatment Sizing an ozone systemOzone systems are sized based on the principle of exact demand. To correctly size an ozone system, each contaminant and contaminant level must be accounted for.An accurate total ozone demand is important for sizing an ozone system.Ozone production is measured in grams per hour.The total ozone demand and water flow rate is needed to calculate for required ozone production.
37 Commercial Water Treatment Sizing an ozone systemOzone demand for each contaminant is calculated by multiplying the contaminant level by the applied dosage appropriate for that contaminant.By adding up the ozone demand for each contaminant, the total ozone demand can be found.A safety factor of 25% should be added to the total ozone demand.
38 Commercial Water Treatment Sizing an ozone systemWith the total ozone demand and water flow rate, the following equation is used to calculate for required ozone production:total ozone dosage X flow rate X X 19 =grams per hour required ozone productionWhere is the constant for conversion from gallons per minute to pounds per day, while 19 is the number of grams per hour in a pound per day.
41 Commercial Water Treatment Design considerationsRecommend single pass ozone injection systems for all commercial water treatment applications - larger systems will use sidetream injectionSizing of sidestream pump is critical - oversize and take into consideration the presssure drop across the injectorMinimum +5 psi required in the sidestream after injection and contacting to re-enter the main stream
42 Commercial Water Treatment Design considerations: contact vesselsContact vessels are an integral part of any ozone system.Allows time for chemical reaction to occur.Allows time for disinfection to occur.Allows for ozone dissolution.Allows for off-gassing of any carrier gas and ozone not dissolved into water
43 Commercial Water Treatment Design considerations for pre-oxidation and oxidation systemsImportance of an accurate lab analysis.Recommend minimum 5 minutes contact time for pre-oxidation systems.Recommend minutes contact time for oxidation systems.Pre-filtration may be required.
44 Commercial Water Treatment Design considerations for pre-oxidation and oxidation systemsOzone is not a stand alone water treatment tool, post filtration is required. Recommend activated carbon or multi-media filtration for pre-oxidation systems. Activated carbon filtration for oxidation systems.Residual sanitizer must be added for storage and delivery.
45 Commercial Water Treatment Design considerations for disinfection:Ozone is not a stand alone water treatment tool, pre and post filtration is required. Recommend multi-stage filtration levels down to 5 micron for pre-filtration and activated carbon for post filtration.Always exceed EPA recommended C.T. values.When meeting C.T. values, use lower ozone concentrations and higher contact times.
46 Commercial Water Treatment Design considerations for disinfection:When calculating for contact time, follow EPA guidelines for time credit - plug flowIf oxidation or pre-oxidation is required in conjunction with disinfection, two complete ozone systems with two injection points and contact/de-gas systems is recommended.Residual sanitizer must be added for storage and delivery.
47 Commercial Water Treatment Design considerations for disinfection:Carcinogenic disinfection by-products may form when ozone is used in the presence of bromide ions - bromate and bromoform ionsDifficult to treat after ozonation - some forms of activated carbon may have effective adsorption or chemical reduction capacitiesLow levels of ozone applied over long periods will minimize the formation of bromate ions.
49 Residential WellsOzone is typically used when more than one contaminant is present.Typically used for pre-oxidation and oxidation.Maybe used for disinfection of bacteria and viruses that may be found in wells with surface water intrusion.
50 Typical Residential Well Water Treatment System
51 Typical Single Pass Ozone System Ozone GeneratorOff-gas DestructOff-gas VentVacuum BreakPressure Tank120V Signal from Pressure SwitchOZDPressure SwitchWell PumpWater from Well PumpContact TankInjection Manifold & Check Valve AssemblyMulti-Media, Activated Carbon or Catalytic Carbon Filter TankWell Pump Controlled by Pressure Switch
52 Alpha SeriesComplete integrated component ozone systems - single pass treatment.Ozone GeneratorOff-gas DestructOff-gas VentVacuum BreakPressure Tank120V Signal from Pressure SwitchOZDPressure SwitchWell PumpWater from Well PumpContact TankInjection Manifold & Check Valve AssemblyMulti-Media, Activated Carbon or Catalytic Carbon Filter TankWell Pump Controlled by Pressure Switch
53 Complete integrated skid mounted ozone systems - recirculated multi-pass treatment. POE SeriesFilter (optional)Pressure TankWater Source (Well)Pressure SwitchTo Use
54 CWT Problem Water Ozone Demand Sizing Guideline Alpha Series PPM Contaminant Level (from water analysis)Ozone Dosage Required per PPM of ContaminantOzone Dosage RequiredPPMContaminantsIron (FE 2+)Manganese (Mn 2+)Sulfide (S 2-)TanninsPPMPPMX0.43=0.88=2.20=1.50=Ozone Dosage RequiredSafety Factor For Unknown DemandTotal Ozone Dosage Required=PPMX1.25=PPMRecommended CWT Ozone Treatment Systems (based on dosage and flow rate):Alpha !Alpha IIAlpha IIIDosage Rate PPM PPM PPMFlow Rate 10 GPM max 10 GPM max 10 GPM max
55 CWT Problem Water Ozone Demand Sizing Guideline POE Series PPM Contaminant Level (from water analysis)Ozone Dosage Required per PPM of ContaminantOzone Dosage RequiredPPMContaminantsIron (FE 2+)Manganese (Mn 2+)Sulfide (S 2-)TanninsPPMPPMX0.43=0.88=2.20=1.50=Ozone Dosage RequiredSafety Factor For Unknown DemandTotal Ozone Dosage Required=PPMX1.25=PPMRecommended CWT Ozone Treatment Systems (based on dosage and flow rate):POE10POE15POE20Dosage Rate PPM PPM PPMFlow Rate 10 GPM max 15 GPM max 15 GPM max
56 Residential Wells ALPHA and POE series sizing notes Sizing based on dosage, residential applications onlyMaximum 10 gpm flow rate for ALPHA series and 15 gpm maximum flow rate for POE seriesOxygen as an oxidizerLong contact timesAssisted by media filtrationResidual build-up through recirculation for POE systemsGuidelines only - additional factors such as pH, temp, ORP, organic load, and other water impurities will affect ozone consumption
57 Residential WellsDesign considerations for residential well treatment systemsImportance of an accurate water analysisDraw down test required to get exact flow rate.Add 1.5 mg/l applied ozone dosage for disinfection of bacteria and viruses.Ozone is not a stand alone water treatment tool, post filtration is required. Recommend activated carbon or multi-media filtration for pre-oxidation systems. Activated carbon filtration for oxidation systems.
67 Miscellaneous Ramblings Factors that affect system performanceWater temperature fluctuationsChanges in water contaminant parametersChanges in flow rateAtmospheric conditions
68 Miscellaneous Ramblings Off-gas destructionOff-gas monitorsImportance of monitoring for water quality using ORP or residual ozone monitorsAutomation capabilities
69 Miscellaneous Ramblings Importance of air prepThe air we breath is composed of 78% nitrogen gas, 21% oxygen gas, and 1% other gases.When air is fed into the ozone reaction chamber, the oxygen and nitrogen molecules are split into atoms.The air we breath is humid (H2O is present).In a highly charged corona field, all molecules are split into atoms.
70 Miscellaneous Ramblings Importance of air prepThe oxygen atoms combine into ozone molecules.The nitrogen, hydrogen, and oxygen atoms combine to form nitric acid.Nitric acid will destroy the reaction chamber from the inside out.Nitric acid will be introduced into the water.
71 Miscellaneous Ramblings Importance of air prep: air dryersAir is dried to -60 degrees F dewpoint using a molecular sieve material, most commonly silica gel.Nitrogen and oxygen atoms are still present but with the removal of moisture, the hydrogen atom is not introduced into the corona field.Ozone concentration: 1% by weight
72 Miscellaneous Ramblings Importance of air prep: oxygen concentratorsHigh volumes of compressed air is pushed through a molecular sieve which removes nitrogen and water.Oxygen concentrations up to 95% are attainable.Minimum -100 degrees F dewpoint.Ozone outputs are tripled. Ozone concentration: minimum 3% by weight.