[[Image{{Language-box|english_link= Ozonation | french_link= Coming soon | spanish_link= Coming soon | hindi_link= Coming soon | malayalam_link= Coming soon | tamil_link= Coming soon | swahili_link=coming soon | korean_link= Coming soon | chinese_link=https:ozone icon//akvopedia.pngorg/wiki/臭氧消毒 |rightindonesian_link= Coming soon |100px]]japanese_link= Coming soon }}
[[Image:ozone icon.png|right|80px]][[Image:ozone generator.jpg|thumb|right|300px200px|Ozone generator by [http://ozonia.com/ozone.php#xf Ozonia.]]][[Image:ozone system.jpg|thumb|right|300px200px|Standard Water Treatment System with Bottling Station that includes ozone. '''Purpose''': bacteriological disinfection; removal of chlorine-resistant organisms. '''Components''': filtration, micro-filtration and ozone. <br>Photo: [http://www.livingwatersfortheworld.org/LWWPO_QF.php Living Waters for the World.]]][[Image:QuickPure ozone purifier.jpg|thumb|right|300px200px|Table top, low-cost, ozone purifier by [http://www.quickpure.com/WaterPurifiers.htm QuickPure.]]]__NOTOC__ <small-title />Ozone is a powerful oxidant [http://en.wikipedia.org/wiki/Oxidizing_agent oxidizing agent] and has many uses in water treatment, including oxidation of organic chemicals. Ozone can be used as a primary disinfectant. Ozone gas (O3) is formed by passing dry air or oxygen through a high-voltage electric field. The resultant ozone-enriched air is dosed directly into the water by means of porous diffusers at the base of baffled contactor tanks. The contactor tanks, typically about 5 m deep,
provide 10–20 minutes of contact time. Dissolution of at least 80% of the applied ozone should be possible, with the remainder contained in the off-gas, which is passed through an ozone destructor and vented to the atmosphere.
Ozone reacts with natural organics to increase their biodegradability, measured as assimilable organic carbon. To avoid undesirable bacterial growth in distribution, ozonation is normally used with subsequent treatment, such as biological filtration or granular activated carbon (GAC), to remove biodegradable organics, followed by a chlorine residual, as ozone does not provide a disinfectant residual. Ozone is effective for the degradation of a wide range of pesticides and other organic chemicals.
===Suitable conditions===
Ozone is currently the next most widely used drinking water disinfectant after chlorine (there are some 1100 water treatment plants
using ozone worldwide), although its use is almost exclusively limited to the industrial countries with high-integrity piped water networks. Ozonation has become popular in North America partly because of its superiority over chlorination. It enhances the coagulation process despite its inherent weakness in leaving practically no residual in the distribution system.
Although ozonation can effectively disinfect water, it is not suited for most developing country applications owing to its high cost, need for operational and maintenance infrastructure, and lack of residual protection in the distribution system.
===Construction, operations and maintenance===
Care is needed in operating and maintaining the generators, and in destroying excess ozone so it is not released into ambient air.
The system requires the use of a water softener and it requires the water to be less than 45 deg C.
===Costs===
The systems are expensive (1million GPD for $1M dollars), but combined units (that include filtration and other methods) or portable units are available.
===Acknowledgements===
* [http://docs.watsan.net/Downloaded_Files/PDF/WHO-2011-Guidelines.pdf Guidelines for Drinking-water Quality] or ([http://apps.who.int/iris/bitstream/10665/44584/1/9789241548151_eng.pdf alternative link]). Fourth edition. WHO, 2011.
* Gadgil, Ashok. [http://www.annualreviews.org/doi/abs/10.1146/annurev.energy.23.1.253?journalCode=energy.2 DRINKING WATER IN DEVELOPING COUNTRIES] or ([http://www.washdoc.info/docsearch/title/120709 alternative link] ). 1998.