FAQ's Ozone

You can also check our Ozone information Overview page.

What is ozone?
How does ozone work?
How is ozone produced?
What is the half-life of ozone?
Is ozone harmful and what are the effects?
How can you tell the level of ozone?

QUESTION: WHAT IS OZONE?

ANSWER: Ozone is a molecule that consists of three oxygen atoms (O₃), with a delta negative and a delta positive electric charge. The ozone molecule is very unstable and has a short half-life. Therefore, it will decay after some time into its original form: oxygen (O₂, according reaction presented below)

2O₃ ⇋ 3O₂

In essence ozone is nothing more than oxygen (O₂), with an extra oxygen atom, formed by an electric high charge an extra oxygen atom. In nature ozone is produced by some chemical reactions. The most familiar example is of course the ozone layer, where ozone is produced from the sun’s ultra-violet (UV) rays. But ozone is also produced at thunderstorms and waterfalls. The extreme high voltages attended with thunderstorms produce ozone from oxygen. The special “fresh, clean, spring rain” smell is a result from nature-produced ozone. Ozone derives from the Greek word ozein, which means to smell.

Ozone is only produced under extreme circumstances. This can also be created by ozone generators. Ozone generators produce ozone with extreme high voltages or with UV-light.

QUESTION: HOW DOES OZONE WORK?

ANSWER: Ozone operates according the principle of oxidation. When the static loaded ozone molecule (O₃) contacts with something “oxidation able”, the charge of the ozone molecule will directly flow over. This is because ozone is very instable and likes to turn back in its original form (O₂). Ozone can oxidize with all kinds of materials, but also odor and microorganisms like viruses, moulds and bacteria’s. The extra oxygen atom releases from the ozone molecule and binds with the other material. Eventually remains only the pure and stable oxygen molecule.

Ozone is one of the strongest oxidation agents technical available for use to oxidize solutes. The extra-added oxygen atom will bind (=oxidation) in a split second to every component that comes into contact with ozone.

Ozone can be used for a broad of area of purification. For the biggest part ozone is applied in the municipal wastewater and potable water treatment plants (for disinfection). However ozone is used more and more in the industrial branch. In the food industry for example ozone is used for disinfection and in the paper- and textile industry it is used for the oxidation of wastewater. The main benefit of ozone is its clean character, because it only oxidizes materials, with forming almost no byproducts. Because ozone has a strong recognizable odor, very low concentrations will soon be perceived. This makes it generally safe to work with ozone.

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QUESTION: HOW IS OZONE PRODUCED?

ANSWER: Ozone can be produced artificially according the same principle as it occurs in nature, which means by UV light (ozone layer) or via corona-discharge (high voltages, thunderstorm). In both methods the connection between the oxygen molecules is broken up. Consequently oxygen radicals are produced, which connect with the oxygen molecule to O₃ (ozone). For the production of ozone, corona discharge is used more because of the greater advantages of this method. Advantages are the lower costs for ozone production (more cost-efficient) and the greater durability of the system. For the feed inlet ambient air can be used as well as pure oxygen. For pure oxygen, oxygen generators can be used to concentrate oxygen out of air. When pure oxygen is used a higher concentration of ozone can be produced.

QUESTION: WHAT IS THE HALF-LIFE OF OZONE?

ANSWER: For the purification of water and air, it’s needed to produce ozone on-site. Because of its short half-life, ozone will decay soon when produced. The half life of ozone in water is about 30 minutes, which means that every half hour the ozone concentration will be reduced to half its initial concentration. For example, when you have 8 g/l, the concentration reduces every 30 minutes as follows: 8; 4; 2; 1; etc. In practice the half-life is shorter because a lot of factors can influence the half-life. Factors are temperature, pH, concentration and concentration and sort solutes. Because ozone reacts with all kinds of components, the concentration ozone will reduce quickly. When most of the components are oxidized, the residual ozone will remain, and the concentration ozone will reduce less fast.

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QUESTION: IS OZONE HARMFUL AND WHAT ARE THE EFFECTS?

ANSWER: At higher concentrations ozone is harmful for human health after inhalation. Several agencies, such as the occupational safety and health agency (OSHA) have proposed MAC-values for ozone. The MAC-value is the Maximum Acceptable Concentration a human is allowed to be exposed to for a certain time and certain agent.
For ozone the MAC-values is 0.06 PPM for 8 hours a day, 5 days a week (PPM = Parts Per Million). For a maximum of 15 minutes a MAC-value of 0.3 PPM is applied.
The concentrations mentioned above are much higher than the odour threshold at which ozone can be smelled, so critical concentrations will be noticed quickly.
When people are exposed to high ozone concentrations the symptoms can vary from dryness in the mouth and throat, coughing, headache and chest restriction. Nearby the lethal limits, more acute problems will follow. When larger ozone generators are applied, ozone destructors can be used for the destruction of residual ozone.

QUESTION: HOW CAN YOU TELL THE LEVEL OF OZONE?

ANSWER: There are a lot of measuring instruments available to measure ozone in water and air. These measuring instruments rest on different principles and can measure the concentrations from PPM (PPM = Parts Per Million) to PPB (= Parts Per Billion). The instruments can be used for monitoring and controlling the ozone generator.

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