Both Ozone and UV are well recognized methods for municipal drinking water treatment and disinfection. Each can be used for the inactivation of viruses, giardia, cryptospordium, bacteria and other microbial contaminants. While UV is limited to disinfection, ozone is also an effective treatment for taste, odor and color removal, iron and manganese reduction, as well as being a flocculating agent. Ozone and/or UV require a relatively short residence times for disinfection unlike chemicals such as chlorine and chlorine derivatives.
Drinking water is treated to kill or inactivate any pathogenic micro-organisms such as viruses, bacteria and parasites, to remove inorganic and organic trace contaminants which have found their way into the water system because of pollution and to reduce the naturally occurring organic compounds such as humic acid and algal metabolites. In general, surface waters such as lakes and rivers contain higher levels of micro-organisms and are more prone to contamination than groundwater and require different treatment regimes. To reduce the risk to consumers, more and more countries are introducing new drinking water regulations containing stricter limits on pathogens and contaminants.
Ozone has been used by municipal bodies for many years to improve the aesthetic qualities of water and for its germicidal action. It is an accepted fact that drinking water is disinfected when a residual ozone level of 0.4 mg/l has been maintained for a period of 4 minutes. Ozone has many additional benefits in the drinking water process: