Ozone - General Information

Ozone is a naturally occurring component of fresh air. It can be produced by the ultraviolet rays of the sun reacting with the Earth's upper atmosphere, which creates a protective ozone layer, or it can 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 predates 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. This process is carried out by 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 ultraviolet 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, microflocculation, 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. When used for iron and manganese oxidation or to induce flocculation, it is usually introduced early, and when used for taste and odor removal it is introduced at an intermediate point. In European water treatment practices, ozonation is recognized as a preferred method of virus inactivation rather then just an alternative to the use of chlorine for disinfection.

Nine out of ten diseases, including the common cold and the flu, are caused by water or airborne bacteria and viruses. 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 waste water treatment. The principal applications for ozonation systems (single ozone generators are rarely sold) are as follows:

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

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