Green Ozone for Water Disinfection

A major consideration with ozone is the rate at which it decomposes spontaneously in water, according to the overall reaction. 

Because of the decomposition of ozone in water, some chlorine must be added to maintain disinfectant throughout the water distribution systan. Although ozone does not produce the undesirable halogenated organics that cause problems with the use of chlorine, it does produce some oxygenated by-products. These include aldehydes (acetaldehyde, H3CC(0)H) and carboxylic acids and their salts (oxalic acid, HO2CCO2H). 

With the caveat that release of toxic ozone to the ambient atmosphere must be avoided (see Section 5.11.7), disinfection of water by ozonation is a virtually ideal example of green chemical practice. The only raw material is universally available air, which is free. Ozone is produced only where it is needed as it is needed, without by-products. The ozone does not persist in water, where it decomposes to elemental oxygen, and there is very little likelihood of producing harmful disinfection by-products with ozone. 

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