OZONE for DISINFECTION 4/16/2017 OZONE for DISINFECTION Cameron Tapp ClearWater Tech, LLC.

Ozone Basics • History of Ozone • How Ozone is Generated

History of Ozone • First discovered in 1840 • From the Greek word “ozein”, which means “to smell” • 1886: Europeans recognize the ability of ozone to disinfect polluted water • 1893: First full scale application using ozone for drinking water in Oudshoorn, Netherlands

History of Ozone • 1906: Ozone first used to disinfect drinking water in Nice, France • 1915: At least 50 major ozone installations on line throughout Europe • 1937: First commercial swimming pool to use ozone in the U.S.A. • 1939: Ozone system displayed at the New York World’s Fair as the future of water treatment • 1940s: Ozone first used in U.S.A. to disinfect municipal drinking water

History of Ozone - City of Los Angeles - 12,000 PPD • 1990s: Ozone gains acceptance in a wide variety of applications - City of Los Angeles - 12,000 PPD - City of Dallas - 16,000 PPD - Also used to treat: • Waste water • Bottled water • Swimming pools & spas • Aquariums • Cooling towers • Soft drinks, breweries, wineries • Food processing

How Ozone is Generated = + = + Ozone (O3) Oxygen (O2) O3 O1 O2 O3 O2 Ultraviolet Light or Corona Discharge Some O2 molecules break apart And reassemble with other O2 molecules to form ozone = O3 O2 + O1

How Ozone is Generated • Man replicates nature to produce ozone in two ways: 1. By forcing oxygen or ambient air past an ultraviolet light source matching the ozone-producing wavelength of the sun’s rays (185 nanometers) 2. By sending a lightning-like spark (a ‘corona discharge’) through an oxygen or dry air flow

How Ozone is Generated • Ozone is highly unstable, and the action involved in killing the microorganisms it contacts causes it to revert back to its original state of biatomic oxygen (O2)

High Voltage Electrode (Anode) How Ozone is Generated 1. Dried air or oxygen is passed through a gap between a glass dielectric and the anode Glass Dielectric Stainless Steel Sleeve (Cathode) High Voltage Electrode (Anode) Gap 2. High voltage current is applied to the anode, which arcs to the cathode. Air in the gap is exposed to the electrical discharge, converting a percentage (1% to 14%) of the oxygen to ozone

What Ozone Does Not Do • Ozone is incapable of oxidizing radon, methane or nitrite ion • Below pH 9, ozone is incapable of oxidizing ammonia at any practical rate • Ozone cannot practically oxidize any of the trihalomethanes, except very slowly

What Ozone Does Not Do • Ozone cannot oxidize chloride ion to produce free chlorine at any practical rate • Ozone cannot oxidize calcium, magnesium, bicarbonate, or carbonate ions; consequently, ozone cannot oxidize hardness or alkalinity ions

What Ozone Does For Problem Water • Disinfection Ozone kills bacteria, cysts etc. up to 3,125 times faster than traditional methods • Taste and Odor Control Ozone oxidizes the organics responsible for 90% of taste and odor-related problems (e.g.: tannin and color removal) For Problem Water

What Ozone Does For Problem Water • Algae Control • Oxidation Ozone effectively kills plankton algae (e.g.: ponds and water features) • Oxidation Ozone’s high oxidation potential can remove many pesticide residuals (e.g.: groundwater remediation) • Preoxidation Ozone’s high oxidation potential can also precipitate iron, manganese, sulfide and metals more quickly than any other commonly used oxidants, aiding removal by direct filtration For Problem Water

Relative Oxidation Reduction Potential of Oxidizing Species Potential Volts Relative Oxidation Reduction Power Species Fluorine 3.06 2.25 Hydroxyl Radical 2.80 2.05 Atomic Oxygen 2.42 1.78 Ozone 2.07 1.52 Hydrogen Peroxide 1.77 1.30 Perhydroxyl Radicals 1.70 1.25 Permanganate 1.67 1.22 Hypochlorous Acid 1.49 1.10 Chlorine* 1.36 1.00 Bromine .78 .57 *Based on chlorine as a Relative Oxidation Reduction Power of 1.00

Oxidation of Typical Contaminants - Iron • Divalent 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 amount of ozone to oxidize 1mg/L Fe is .43 mg/L • If complexed with organics, longer contact times and higher doses are recommended For Problem Water

Oxidation of Typical Contaminants - Manganese • Divalent manganese (Mn2+) oxidizes to tetravalent (Mn4+), hydrolyzing to insoluble manganese oxydihydroxide • Over oxidation will produce soluble permanganate ion (indicated by pink tint to water) • Optimum pH range is 7.5 - 8.5 • Theoretical amount of ozone to oxidize 1 mg/L Mn is .87 mg/L For Problem Water

Oxidation of Typical Contaminants - Sulfide Ion • Hydrogen sulfide ion is oxidized to soluble sulfate ion and insoluble sulfur • Rapid reaction • Theoretical amount of ozone to oxidize 1 mg/L sulfide ion is 1.5 mg/L For Problem Water

Oxidation of Typical Contaminants - Color • Primarily composed of humic and fulvic acids • No set dosage • Complete color removal typically requires high dosages • Filtration not always necessary For Problem Water

Sizing Basics • Preoxidation system for iron, manganese and sulfide removal: Ozone Required To Treat: Stoichiometric Practical 1 PPM Iron (Fe++) Requires .43 PPM .5 -.14 PPM 1 PPM Manganese (Mn++) Requires .88 PPM 1.5 - .6 PPM 1PPM Sulfide (S2) Requires 6 PPM 1.5 - .5 PPM

Example Applied Dosage Calculation Ozone Dosage Required for Iron/manganese Removal (Water flow at 10 gpm with 1.3 PPM Iron and .22 Manganese) Ozone Dosage Required = 1.3 (Fe) X .43 (O3) = .56 ppm = .22 (Mn) X .88 (O3) = .19 ppm Ozone Required = .75 ppm Dosage added for unknown demand = .75 ppm Recommended Total Ozone Dosage = 1.50 ppm 1.50 (dosage) X 10 gpm X .012* X 19* = 3.42 g/h *.012 is the constant for conversion from gallons per minute (GPM) to pounds per day (PPD) while 19 is the number of grams per hour in a pound per day. In this example, 3.42 g/h is the output of the ozone generator required. Sizing Basics

Factors That Affect System Performance • Fluctuations in water temperature • Changes in water contamination levels • Changes in water flow rate • Varying atmospheric conditions Sizing Basics

Mass Transfer Basics • Definition: The movement of molecules of a substance to and across an interface from one phase to another i.e.: The amount (mass) of ozone that transfers from air, across the air-water interface and into water

Mass Transfer Basics • Factors affecting transfer of a gas into a liquid: Pressure: As pressure increases, more gas is forced into the liquid Temperature of the water/gas mixture: At lower temperatures, ozone gas is more easily absorbed by the liquid. At higher temperatures, water tends to release gas rather than absorb it Bubble size: As a gas is broken into more small bubbles, the total bubble surface area increases, enlarging the area for interaction between ozone and water Concentration of ozone in the carrier gas: Increased concentration of ozone enhances the ability of ozone to be absorbed into water

Ozone Contact Time • The Contact Vessel An integral part of any ozone system Allows time for chemical reactions (precipitation) to occur Allows time for disinfection to occur Allows for ozone dissolution Allows for off-gassing of any remaining carrier gas and ozone not dissolved into the water

CT Value Defined Contact Time • C = the residual concentration of the disinfectant (expressed in mg/L) measured at or before the first point of consumption • T = The contact time (expressed in minutes) required for water to travel from the point of injection to the point where C is measured • Example: A 0.4 residual after 4 minutes of contact time will yield a value of 1.6 (.4 x 4 = 1.6) Tables have been established to help determine CT values required for certain levels of disinfection at various water temperatures and pH readings Contact Time

CT Values for Giardia Cyst Inactivation by Ozone: (pH can be anywhere between 6 and 9) at various water temperatures (Source: EPA, SWTR Guidance Manual, 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°F 0.5 log 0.48 0.32 0.23 0.16 0.12 0.08 1.0 log 0.97 0.63 0.48 0.32 0.24 0.16 1.5 log 1.50 0.95 0.72 0.48 0.36 0.24 2.0 log 1.90 1.30 0.95 0.63 0.48 0.32 2.5 log 2.40 1.60 1.20 0.79 0.60 0.40 3.0 log 2.90 1.90 1.40 0.95 0.72 0.48 CT Values for Giardia Cyst Inactivation by Free Chlorine: Water temperature at 20˚C (68˚F) at various pH readings Removal <6.0 6.5 7.0 7.5 8.0 8.5 <9.0 0.6 log 38 45 54 64 77 92 109 1.0 log 39 47 56 67 81 98 117 1.6 log 42 50 59 72 87 105 126 2.0 log 44 52 62 75 91 110 132 2.6 log 46 55 66 80 97 117 141 3.0 log 47 57 68 83 101 122 146

Significant Points About CT • Ozone kills bacteria very quickly and effectively on contact • Viruses and cysts, respectively, require increasingly greater CT values. To maximize CT effectiveness, longer contact times should be emphasized over higher ozone concentrations • Disinfectants for which CT values have been established: Free Chlorine Chloramines Chlorine Dioxide Ozone

Typical Installation Clarification Ozone Contactor Filtration Surface water Clarification Residual Sanitizer Added Ozone Contactor Filtration

Benefits of Ozone Use • Generated on site No transportation, storage or handling challenges • More powerful than chlorine Chlorine’s relative oxidation reduction power = 1.00. Ozone = 1.52. • Reverts to oxygen leaving no telltale taste or odor to be removed Greatly simplifies water chemistry, control and convenience.

Benefits of Ozone Use • Creates no carcinogenic by-products, i.e., trihalomethanes (THMs) New surface water treatment plants require ozone to meet modern THM regulations Ozone’s only by-product is oxygen • Ozone is the only recognized disinfectant capable of practical inactivation of Cryptosporidium oocysts with CT requirements about 3 to 5 times those for Giardia cysts

Large Commercial Ozone Plant 750 PPD

Skid-Mounted Package Plant 650 PPD

Installing Dielectrics

1 mgd Small Community Plant Commercial Units

Disinfection Technology Comparison ClearWater Tech, LLC

Applicability of Disinfection Techniques

Chlorine Advantages and Disadvantages • Readily available • Known technology • Long half life • Simplicity Disadvantages • High CT values • Highly toxic • pH dependent • Transportation issues

Ozone Advantages and Disadvantages • Low CT values • No by-products • Strongest oxidizer commercially available • Generated on site • Effective for THM control • Effective against Crypto Disadvantages • Capital cost • Larger footprint • Higher service and maintenance

UV Advantages and Disadvantages • High reliability • No by-products • Generated on site • Effective against viruses and bacteria Disadvantages • Initial capital cost • No chemical residual • Higher service requirements

Conclusion • No single water treatment method is the panacea for all types of water conditions. Typically, using the combined strengths of several methods will produce the best overall results.

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