Aurozon Thattanchavady, Pondicherry

Ozone disinfects water and kills bacteriae by oxidation of specific cell wall components. However, ozone will oxidize many different types of chemical species both organic and inorganic. For example if the water has a high concentration of manganese, iron, proteins or other organics then these components will effectively reduce the available concentration of ozone in the water, and hence the germicidal properties of the gas. As a rough guide (or a rule of the thumb) if you wish to achieve near 100% disinfection of the water, the applied ozone concentration should be equivalent to atleast 50% of the COD. For example, if the COD is 2mgl, then the ozone requirement should be atleast 1 mgl. You should only use this figure as a guide. Alternatively the ‘Ozone demand’ can be estimated experimentally.