Ozone: Putting the record straight
Ozone, or activated ozone as it is sometimes known, is produced commercially from oxygen using a high-voltage charge. This happens naturally in lightning storms and produces the clean, fresh smell which follows them. Jon Fielder explains.Ozone was discovered by Van Marum in 1785, and was first used commercially for disinfection of water in 1893. Today's concerns about the biological and environmental risks of traditional disinfectants make ozone the natural choice for a growing number of applications. Its benefits include:
- Being nature's own disinfectant
- Being non-polluting
- Being environmentally friendly
- Being safe for discharge direct to rivers and streams without risk to plant and aquatic life
When mixed with water, ozone produces an oxidising disinfectant or biocide many times more powerful than chlorine, yet with none of the pollution and environmental risks associated with chemical biocides.
It is readily soluble in water with a half-life in water of ten to 20 minutes under normal conditions.
Drinking water can be routinely disinfected or sterilised using ozone, making it safe for drinking without leaving chemical residue or taint. As it breaks down rapidly to normal oxygen, ozone does not pollute or contaminate the water which, once disinfected, can be recycled and reused without any safety risks.
Being 100% effective against all bacteria, algae, viruses, cysts and occusts, ozone destroys all pathogenic and harmful organisms without any risk of immunity developing. Ozone does not kill bacteria and viruses by toxicity or poisoning, it operates by oxidising and destroying the chemical make up of the cells of organisms whether they are alive or dead. Provided sufficient ozone is applied, destruction is instant and complete.
In the past 50 years, there has been a rapid growth in ozone usage for an increasing range of applications, mainly due to:
- Research into ozone technology and the development of ozone generators
- Recognition of the limitations, biological hazards and environmental impact of historically used oxidants and disinfectants
- The phenomenal increase in environmental pollution
Hydrocarbon emissions from vehicles and industry combine with other contaminants to produce smog. Ozone is produced as a by-product of the photochemical reaction of sunlight and these pollutants.
As ozone is relatively easy to detect, and the quantity of ozone is proportional to the pollution and sunlight, it is used as a measure of pollution in built-up areas.
In fact, ozone has the beneficial effect of oxidising the pollutants to assist in breaking down and cleaning the pollution. Ozone is a consequence of pollution and part of the cleaning process, not a cause.
Ozone is used in water treatment primarily because of its oxidative strength. This powerful oxidation potential makes ozone effective in:
- Elimination of colour, taste and odour
- Destruction of bacteria and inactivation of viruses
- Breakdown of organic contaminants
- Oxidation of metal contaminants, including iron and manganese
- Liberation of organically bound heavy metals, otherwise not easily moved.
- Removing and preventing biofilms in process water systems
- CIP disinfection of process water loops and systems
- Washing and disinfection of equipment and food products
- Rinsing and disinfection of containers and tankers
- Biological control in cooling towers
- Treatment and disinfection of water for recycling
Jon Fielder is technical director at Waterwise Technology.
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