General Information

Ozone is a naturally occurring component of fresh air. The ultra-violet rays of the sun reacting with the Earth’s upper atmosphere can produce it. This creates the protective ozone layer. It can also be created artificially with an ozone generator. The ozone molecule contains three oxygen atoms whereas the oxygen molecule contains only two.

Ozone is a very reactive and unstable gas with a short half-life before it reverts back to oxygen.

Ozone is the most powerful and rapid acting oxidizer man can produce, and will oxidize all bacteria, mould and yeast spores, organic material and viruses.

A Brief History of Ozone

Ozone has played a significant role in the waste treatment process in the past and will continue to do so in the future. The utilization of ozone in industrial situations has a long and impressive history, one that pre-dates current environmental concerns. The American Indians, for whom fishing was a central industry, recognized a correlation between a successful catch and a strange odor released by the action of lightning after an electric storm. On the other side of the globe the ever-astute Greeks had also noticed the odor (and so defined it “ozein”) and like the Indians, preferred fishing after a storm, which is still practiced today. The explanation for this natural phenomenon is that after an electric storm the upper layer of water in lakes is enriched with diluted oxygen and therefore naturally ozonated. The positive influence of ozone on the digestive system of different species of fish has been scientifically documented. The closed loop for fish farming is only possible with ozone because of its ability to destroy viruses responsible for many diseases in fish culture. The most common use of ozone is for the treatment of water. In 1906 group of scientists and doctors studied the ozonation system at the Oudshoorn plant in Holland and later constructed a 19,000 m3/day (5 mgd) plant using ozonation for disinfection - at Nice, France. Nice is therefore referred to as “the birthplace of ozonation for drinking water treatment”.

Formation of Ozone

The formation of oxygen into ozone occurs with the use of energy. In nature, Ozone is formed during thunderstorms. In industry, this process is copied by artificially producing an electric discharge field as in the CD-type ozone generators (corona discharge -simulation of the lightning), or by ultraviolet radiation as in UV-type ozone generators (simulation of the ultra-violet rays from the sun). In addition to these commercial methods, ozone may also be made through electrolytic and chemical reactions.

Ozone And Its Applications

Ozone is not only a very powerful oxidizing agent but also a very powerful non-chemical disinfectant. It has the unique feature of decomposing to a harmless nontoxic environmentally safe material, namely oxygen.

In Europe, ozone is used for many purposes: color removal, taste and odor removal, turbidity reduction, organics removal, micro flocculation, iron and manganese oxidation, and most commonly, bacterial disinfection and viral inactivation.

Most of these applications are based on ozone’s high oxidizing power. Ozone can be introduced at different points in the water treatment process, depending on its intended application. Ozonation is recognized as a preferred method of virus inactivation rather then just an alternative to the use of chlorine for disinfection.

Water or airborne bacteria and viruses cause Nine out of ten diseases, including the common cold and the flu. Like chlorine, ozone kills microorganisms. The sterilization action of ozone is by “direct kill attack” and oxidation of the biological material. The rate of bacteria killed by Ozone is 3500 times faster than with chlorine. Virus destruction with ozone is instantaneous, safe and foolproof, as ozone is nature’s own purifier. Chlorine’s reactive oxidant is hypochloric acid, which is formed when chlorine is dissolved in water. This powerful oxidant will have significant long-term negative effects on our water sources. Ozone, on the other hand, has no side effects as far as the treatment of water is concerned. It has properly been described as the “add-nothing” sterilant.

In Eastern Canada, there are approximately 100 ozone plants for the treatment of municipal water, as well as many large industrial plants for water processing and wastewater treatment. The principal applications for ozonation systems (single ozone generators are rarely sold) are as follows:

Air Treatment, Aquaculture, Bottled water, Cooling towers, Fish boats, Fish canneries Fish hatcheries, Hot springs, pools, Industrial waste, Odor Control, Process water, Pools and Spa, Potable water, Therapeutic use, Waste water.

There are hundreds of commercial applications and new emerging applications being developed.

Other Ozone Facts

In 1957, the US Department of Agriculture approved the use of gaseous ozone for meat storage and disinfection.

In 1982, the FDA affirmed GRAS (Generally Recognized As Safe) status for ozone specifically for bottled water.

In 1991, the US Environmental Protection Agency confirmed that ozone is the most effective primary disinfectant available for drinking water. Today, more than 200 US drinking water plants use ozonation, and that number will jump as cities comply with EPA’s forthcoming standards in 1999, which will require the inactivation of Crytosporidium, which chlorine doesn’t eradicate.

Now, ozone has been declared safe for use in food processing by the FDA. The FDA confirmed the affirmation of GRAS status in June 1997. To attain GRAS affirmation for ozone for food processing, EPRI followed the FDA’s guidelines and assembled a panel of six top experts in food science, nutrition, toxicology and ozone chemistry. The Institute also undertook an extensive, worldwide search for scientific and historical documents describing the use of ozone in food processing. In reviewing these data, the experts considered ozone’s safety, toxicology, impact on nutrients, and efficacy in food processing. The panel members communicated regularly via conference calls and faxes and convened periodically in Washington, DC to review their findings. After 15 months of intensive investigation, they released and signed their assessment, concluding that “ . . .the available information supports a GRAS classification of ozone as a sanitizer or disinfectant for foods when used at levels and by methods of application consistent with Good Manufacturing Practices.” This GRAS ruling covers both gaseous ozone and ozone in water for food processing, storage and disinfection.”

This report was published in the EPRI Journal of July/August 1997.

The report goes on to say: “Ozone is widely used in the pharmaceutical industry to generate the ultra pure water needed in its manufacturing processes. Typically, water is purified and transferred to a storage tank until needed. Ozonation keeps the water free of bacteria, a critical task, since a number of pharmaceuticals are made biochemically and the introduction of unwanted bacteria could result in unwanted chemical compounds. In an even more established application, the pharmaceutical industry also uses ozone as an oxidant in its manufacturing processes. Unlike chlorine, ozone does the job without leaving behind residuals to disrupt the chemical reactions underway. It’s also highly selective – that is, capable of targeting certain functional groups within a chemical compound without affecting the rest of the compound.”

The report goes on to list other uses of ozone: as a soil fumigants; as an aid in agricultural drip irrigation systems; as a purifier of the high-quality water required for dialysis in hospitals; in recycling of saltwater in major aquariums and fish farms; and as a pool disinfectant at the 1984 Los Angeles and 1996 Atlanta Olympic Games.