12/06/2020
Some information on ozonation
"Ozone is a remarkably versatile and powerful disinfectant, although the need to produce it onsite makes it expensive compared to alternatives such as chlorination or UV. First used for drinking water disinfection in 1893, by 1920 it was established as a major water disinfection process used throughout continental Europe. The cheapness of chlorine and the lack of a residual disinfection capability led to its replacement by chlorination almost universally by the 1970s. However, the presence of micropollutants in water, mainly pesticides and pharmaceuticals, and the rise of halogenated disinfection by-products such as trihalomethanes formed during chlorination, has led to renewed interest in ozonation for the oxidation of organic compounds and pathogens. The chemistry of ozone is explained, as is dosing and process technology. Its ability to oxidize a wide range of organic and inorganic compounds gives it significant extra value to operators, especially in relation to stricter standards relating to trace organics such as pesticides and chlorine-derived disinfection by-products. Ozone itself can also produce a range of disinfection by-products, most notably bromate. Ozonation is undergoing a renaissance, especially being adopted for surface supplies that suffer from runoff contamination. It is especially effective against the cysts and oocysts of protozoan pathogens. While ozone is an effective disinfectant against all waterborne pathogens, it is generally followed by low-level chlorination to ensure residual disinfection as treated water makes its way through the distribution mains to the consumer."
