Ozone oxidation is by far the most effective water treatment process. It is also the most ecologically sound process as ozone is a natural gas that breaks down into oxygen within a short period of time.
What makes ozone this effective is its high oxidation potential (2.07V), i.e. its potential to react with other substances. The oxidation potential of ozone can be measured by the redox potential and comparing, ozone is about five times more oxidizing than oxygen and about twice as oxidizing as chlorine. Ozone has a well-documented kill rate of microorganisms such as fungus, bacteria and viruses. The high kill rate makes it possible to shorten the retention times and use smaller reaction tanks compared to disinfecting with other oxidants. In other words the investment cost for tanks and treatment plants are reduced considerably.
Apart from killing microorganisms ozone can be used to controls taste, odor and color. It can also be used for flocculation of organic material which simplifies for mechanical filtration.
The oxygen – ozone cycle
Ozone is essentially made up by oxygen. When an oxygen molecule (O2) is exposed to electric high voltage (or UV-light in the stratosphere), the oxygen molecule (O2) is split into two oxygen atoms (O1). The oxygen atom (O1) then connects to oxygen molecules (O2) and ozone (O3) is formed. Ozone then reacts with other substances and the single oxygen atom (O1) disconnects from the ozone molecule (O3), which then again turns into an oxygen molecule.
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Ozone is a natural gas
Ozone is an unstable gas with a very short half-life, which means that it reacts and disappears very fast. Ozone exists naturally in the atmosphere where it is a vital gas that protects us from harmful UV-radiation. The highest concentration of ozone is found in the stratosphere, which is also called the ozone layer.
Ground-level ozone is a greenhouse gas and can be harmful to the environment due to its high oxidation potential. Ground-level ozone is created as a reaction from certain air pollutants and sun light (UV-light), called the photolysis reaction. The highest levels of ground-level ozone are found in much polluted cities like for example Mexico City or Huston, Texas.
Ozone produced by ozone generators is harmless to the environment.