Sterilization Using Ozone

Ozone (O3) is a powerful oxidant, and application to effluent treatment has developed slowly because of relatively high capital and energy costs compared to chlorine. Energy requirements for ozone are in the range of 10 to 13 kWh/lb 

The odor control market is the largest and much of this market is in sewage treatment plants. Use of ozone for odor control is comparatively simple and efficient. The application is for preservation of environmental quality in addition, alternative treatment schemes requiring either liquid chemical oxidants (like permanganate or hydrogen perioxide) or incineration can significantly increase capital and costs. 

Ozone applications in the United States for drinking water are far fewer than in Europe. However, the potential market is large, if environmental or health needs ever conclude that an alternate disinfectant to chlorine should be required. Although energy costs of ozonation are higher than those for chlorination, they may be comparable to combined costs of chlorination dechlorination-reaeration, which is a more equivalent technique. One of ozone s greatest potential uses is for municipal wastewater disinfection. 

Technical, economic, and environmental advantages exist for ozone bleaching of pulp in the paper industry as an alternate to hypochlorite or chlorine bleaching which yields deleterious compounds to the environment. 

Over 100 years ago it had been demonstrated that ozone (Oj). the unstable triatomic allotrope of oxygen, could destroy molds and bacteria and by 1892 several experimental ozone plants were in operation in Europe. In the 1920s, however, as a result of wartime research, during World War I, chlorine became readily 

---

Today in addition to Paris, many other cities use ozone in production of potable water. Zurich, Switzerland, Florence, Italy, Brussels, Belgium, Marseille, France, Singapore and Moscow, Russia all have ozone water treatment plants. In Europe many swimming pools, both public and private use ozone in place of chlorine. With ozone, no salts are added to the water, so that in addition to a high level of sterility, the acidity (pH) is easier to control. In the United States, ozone s use is limited, but LaSalle, Illinois has a relatively new ozone water treatment facility. ... 

Table 12-2. Phenomenological Reaction Rate Coefficients for Plasma Sterilization of Bacteria (E. coli) using Ozone O3, Hydroxyl Radicals (OH), and UV Radiation...

Sterilization of the surfaces of vessels, pipes and valves may be achieved by heat, radiation or chemicals [81]. The use of steam has already been mentioned apart from cost it tends to be a slow procedure for sterilizing brewery vessels when steam pressures are low. Furthermore, it may carry undesirable particles and odours while the condensate is often drained unsatisfactorily. Radiation sterilization is rare although ultraviolet light irradiation is used for the treatment of water on a continuous basis. One of the simplest chemicals used for sterilization is ozone but this has proved corrosive [82]. More widely employed is hydrogen peroxide which, with peracetic acid, is added to soak baths for flexible pipes and items of fermentation equipment. 

In order to reduce the chances of disease in the hatchery, disinfection of the inlet water is crucial. Disinfection can reduce the amount of fish pathogens typically as much as 99.9 % (log 3), although complete sterilization is practically impossible. The most common system is ultraviolet (UV), but it is also possible to use ozone (Summerfelt, 2003 Masters et a/., 2008). Disinfection should be carried out after particle removal in order to avoid any negative influence from the particles during disinfection, UV shadowing, or unnecessary reduction of the ozone concentration. 

Pharmaceutical Industry. In the pharmaceutical industry, sterility of deionized water systems is maintained by using an ozone residual. The ozone residual concentration is maintained at >0.3 ppm ppm in the water recirculation loop. Prior to product compounding, the ozone residual is removed by contact with uvirradiaton for <1 s. Ozone also is used to oxidize pyrogens from distilled water destined for intravenous solutions. 

Chlorine Dioxide. Like ozone, chlorine dioxide [10049-04-4] is a powerflil oxidant. It is usually generated as used. It has been used for disinfecting drinking water and bleaching paper pulp. Its effectiveness in killing microorganisms is well documented (305,306), and it has received recent study as a gas to sterilize medical devices. It requites 50% rh or higher to be effective. Bacterial cells had a D-value of 2.6 min and spores of 24 min (307). 

Besides the disinfeetion of sewage effluent, ozone is used for sterilizing industrial containers sueh as plastic bottles, where heat treatment is inappropriate. Breweries... 

Ozone can also be used as an oxidizing agent, but because of its instability, it must be generated on-site. It is a powerful oxidant for some organic materials, but others are oxidized only slowly or not at all. Ozone is only suitable for low concentrations of oxidizable materials. A common use is for the sterilization of water. 

Sterilization. In some processes, such as food and beverage and pharmaceutical processes, water might need to be sterilized before it is reused or recycled. Chemical oxidation (e.g. ozonation) can be used. Ultraviolet light is an alternative for lightly contaminated water. Alternatively, a combination of chemical oxidation and UV light can be... 

Lead dichloride occurs in nature as the mineral cotunnite. The compound is used in making many basic chlorides, such as Pattison s lead white. Turner s Patent Yellow, and Verona Yellow, used as pigments. Also, it is used as a flux for galvanizing steel as a flame retardant in nylon wire coatings as a cathode for seawater batteries to remove H2S and ozone from effluent gases as a sterilization indicator as a polymerization catalyst for alpha-olefins and as a co-catalyst in manufacturing acrylonitrile. 

Ozone has many industrial applications. It is a sterilizing and deodorizing agent. It is used for disinfection of filtered drinking water and to purify waste-waters. It also is used in water treatment plants for removal of metal impurities by oxidizing them into insoluble compounds. This removes undesired taste, odor, and color from the water. Ozone also is used for odor control. 

Since no added substances are allowed, if chloride and ozone are applied in the preparation of purified water, the following should be ensured tests for total organic carbon and conductivity apply to purified water produced on site for use in manufacturing. Purified water packaged in bulk for commercial use elsewhere shall meet requirements of all tests under sterile purified water, except labeling and sterility, per USP XXIV. 

Nevertheless, ozone is beneficial in at least three ways. It is an excellent disinfectant and is used increasingly to sterilize municipal water supplies (Section 14.7). It can also be used as a powerful oxidant in the chemical process industries. Finally, O3 is an important constituent of the ozone layer in the stratosphere. The ozone layer absorbs short-wavelength ultra-... 

Ultraviolet (uv) light has also been used to sterilize the water in aquaculture systems. The effectiveness of uv decreases with the thickness of the water column being treated, so the water is usually flowed past uv lights as a thin film (alternatively, the water may flow through a tube a few cm in diameter that is surrounded by uv lights). Uv systems require more routine maintenance than ozone systems. Uv bulbs lose their power with time and need... 

High up in the atmosphere, around 20 km from the surface of the earth, the ozone layer acts as a shield and protects the earth from the harmful UV rays present in the incoming solar radiation. But for this layer, all life on earth would have been scorched. Ozone is used to sterilize drinking water and to remove bad odours and tastes. 

One of the most effective fumigants is methyl bromide. It essentially sterilizes soil when applied under a ground covering, because it kills insects, nematodes, and weed seed but also is used to fumigate warehouses. Overexposure to this compound causes respiratory distress, cardiac arrest, and central nervous effects. The inhalation LC50 is 0.06 mg/L (15 min) of air (rat) and 7900 ppm (1.5 h) (human). Methyl bromide has been classified as an ozone depleter under the Clean Air Act and is due to be phased out of use by 2005. 

Because sap is a perishable product, it is generally processed relatively soon after collection to minimize microbial contamination and the accompanying reduction in syrup quality. Sap is often filtered and UV-sterilized after collection to reduce microbial loads in order to maintain sap quality. Ozone treatment, although useful in water treatment, does not appear to be effective in maple applications, presumably due to the strong protective effect of sugars on microbial populations (Labbe et al, 2001). 

---