Ozone water purifying systems have been used by water treatment plants since the late 19th century, after European scientists discovered their effects on waterborne contaminants. Water treatment has become very important in recent decades, as clean water supplies continue to decline. As the negative effects and limitations of chlorination have become apparent, municipal water providers have turned to alternative methods of water purification.
An ozone water purifier works by passing ozone gas through the water, eliminating a wide spectrum of contaminants as it comes in contact with them. Ozone kills more bacteria and viruses than chlorination, and can also help remove minerals like iron, sulfur and manganese by oxidizing them, transforming them into a form that can be easily removed by filtration.
Ozone has been used in Europe for water treatment since the early 20th century. Initial applications were to disinfect the relatively clean spring or well water, but they evolved more and more to oxidize contaminants common to surface waters. Since World War II, ozonation has become the main method of securing drinking water in Switzerland, West Germany and France. More recently, important freshwater and sewage treatment facilities using ozone water treatment methods have been built around the world. Relatively, the use of ozone for water treatment and purification in the United States has been much more limited. However, ozone use has increased here in the US, particularly during the last decade as the negative effects of chlorination have become more apparent. For example, the city of Los Angeles has built a modern water treatment plant in the United States to use ozone for primary disinfection and microflocculation of up to 600 million gallons of water per day.
Ozone is a powerful oxidizer with high disinfectant capacity. One study found that within a pH range of 6 to 10, 3 to 10 C, and with ozone residues between 0.3 and 2.0 mg / L, bacteriophage MS-2 (a substitute test organism) And Hepatitis A virus were completely inactivated. Inactivations ranged from> 3.9 log and> 6-log, and occurred in very short contact periods (ie, 5 seconds). A 1992 research report describes the treatment studies performed on MS-2, poliovirus and Giardia cysts. In addition, Giardia muris and enteric viruses can be inactivated by ozone (as primary disinfectant) with a contact time of 5 minutes and ozone residues from 0.5 to 0.6 mg / L to 3-log and 4-log removals, respectively. The report concludes that ozone design as the primary treatment should be based on simple criteria such as residual ozone, competitive ozone demands and minimum contact time to meet the required cyst and viral inactivation requirements, in combination with the ozone recommendations. The EPA has reviewed survey data submitted by the International Ozone Association and found that ozone has been applied in many drinking water treatment facilities in the USA. With capacities greater than 100,000 gal / day and some smaller installations for disinfection as well as for other water treatment targets. Applications in the smaller water size category.