Sterilization ozone effect

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). 

Ozone is the fourth strongest oxidant known to man and is more effective at sterilizing water than chlorine. Ozone s reaction with NO is a natural phenomenon that takes place in the upper atmosphere that depletes the ozone layer and creates acid... 

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... 

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). 

Ozone is toxic to all forms of life and can be used only very sparingly in the continuous treatment of rivers and lakes. Ozone is used to control the quality of water in aquaculture. In this application, it sterilizes the water before it is allowed into the tanks used to grow the fish. Ozone completely kills all bacteria, viruses, parasite eggs, and fungus spores. In aquaculture, it is far more effectively than chlorine. Unlike chlorine that makes the water salty ozone decomposes to useful oxygen. With properly control, it is a preferred method of protecting fish from waterborne disease. It has also been used to aid in controlling the spread of Zebra Mussels. 

In the framework of the aforementioned kinetic model of plasma sterilization, the following formula describes the rate of inactivation of airborne micro-organisms inside a DBD from the combination of effects of ozone, hydroxyl, and UV radiation ... 

The final step normally involves treating the water with a chemical agent to ensure the destruction of bacteria. Ozone is more effective, but chlorine is less expensive. Liquefied CI2 is dispensed from tanks through a metering device directly into the water supply. The amount used depends on the presence of other substances with which the chlorine might react and on the concentrations of bacteria and viruses to be removed. The sterilizing action of chlorine is probabty due not to CI2 itself but to hypochlorous acid, which forms when chlorine reacts with water ... 

Regular ozone treatment is effective for sterility, and is used in high-purity water systems. 

Concern over the adverse health effects of trace amounts of THMs produced during the chlorination of drinking water has led to the use of nonchlorin-ated disinfection agents, such as ozone (O3), in the treatment of domestic water, particularly in Europe. Ozone has not been extensively employed in the United States because it is difficult to maintain an active residual once the water leaves the treatment plant. Ozone gas is also used in hospitals to sterilize instruments and surgical dressings. 

Ultraviolet (UV) light is directly effective against microbes. Unfortunately, it has low penetrative capabilities and even a thin film will serve as an effective barrier between radiation and microbes. Thus, its use is generally restricted to laboratory applications for surface sterilization. Skin and eyes must be shielded (by glass) from continued exposure to UV light. Ozone (O3) is being used in water treatment. Ozone degrades rapidly in warm water (>35°G/95°F). Thus, at present, its primary application is cold-water recirculation systems. 

Carbons modified with fluorine [112] and nitrogen [113,114] have also been extensively studied as catalysts in fuel cells leading to improvements in performance for both oxygen reduction and methanol oxidation. Both decrease in overpotentials and increase in lifetimes have been reported. The application of similar concepts to electrode materials for effluent/water treatment is likely to lead to electrodes with greater stability. A nitrogen-doped diamond-like carbon has been shown to be effective for generation of ozone in water and the resulting solution employed to sterilize water oiEscherichia coli [115]. 

New technologies provide commodity PO with modified sensitivity to degradation. Depletion of the ozone layer accounting for a potential increase in the intensity of UV radiation should be anticipated by relevant UV stabilizers. Effective radiation-resistant protection during and after sterilization by energetic radiation is necessary. 

Ozone exhibits a 100% bacteriological effect at concentrations of 0.023 mg/1 without producing spores. Spores are destroyed at 0.61 mg/1 [247], At the same concentration, 87.5% of the hepatic virus B is inactivated. Large amounts of blood can be conserved without clotting by bubbling with oxygen-ozone mixture. Parallel to this, all the microbial materials in blood are oxidized, thus sterilizing it [266]. 

Usually sterilization is performed at sufficiently high temperatures that may cause damage on same materials used in food processing industry, pharmaceutical industry and cosmetics. The effect of ozone on bacteria is well known, especially its toxicity and reactivity characteristics that is why attention should be given to dosage and C5q)osure time. 

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