Ozone Technology and Ozone Chemistry

History of Ozone

  • 1840 - Discovered by Schönbein
  • 1893 - Used as a disinfectant in drinking water
  • 1909 - Used as a food preservative for cold storage of meats
  • 1939 - Was found to prevent the growth of yeast & mold during the storage of fruits
  • 1982 - FDA GRAS declaration for ozone use in bottled water
  • 1995 - FDA GRAS for ozone use in bottled water renewed without change
  • 1997 - Industry Expert Panel declares ozone GRAS and meets FDA requirements.            Regulators have the option to later add control on ozone use.
  • 1999 - USDA rejects an ozone use protocol for meats, cites 1982 GRAS declaration for            water where FDA stated "any other use must be regulated by a Food Additive            Petition."
  • 2000 - Food Additive Petition, that addresses both water and air use of ozone, under            preparation. FDA estimates approval will occur within six months of submission of            the Petition
  • 2000 - 2004: Implementation Stage EPA - Disinfection By-Product Rules (DBPR)
               Today :Ozone is EPA listed as DBPR compliant
Properties of Ozone (O3)

Ozone is a gas - triatomic form of oxygen. It most powerful oxidizing agent available for conventional water treatment. It is highly reactive and unstable – therefore it must be generated and used on-site. The weak bond holding ozone's third oxygen atom is what causes the molecule to be unstable and thus, very effective as an oxidizer. Ozone is only partially soluble in water, but more so than oxygen. The best property of ozone is that after all its actions it ultimately reverts to environmentally friendly oxygen.


Ozone chemistry is composed of a single bond and one double bond. The single bonds are weak and this leads t easy formation of free radicals. The double bond is as strong as the double bond of oxygen and so un reactive. Two resonance structure of ozone exists and they are inter convertible. The inter-convertibility is so fast that at point of time ozone as seen as a blend of the two resonance structure .The strength of these two bonds are equal


As an Oxidant ozone is more powerful that Oxygen. This difference is due to the oxidation states .In water the oxidation state of the hydrogen atoms is +1 and that of oxygen atom is -2 ( hydrogen as yielded its electron to oxygen and oxygen as acquired an electron from each hydrogen atom ) The Oxidation State for oxygen atoms is usually - 2. However, in both ozone and molecular oxygen, the oxygen atoms each have an oxidation state of 0. Therefore, ozone and oxygen are both oxidants because they are capable of drawing electrons from a source, decreasing the oxidation State of at least one of their oxygen atoms in the process.

OZONE is more reactive than oxygen because ozone can readily react with substrate on its own whereas oxygen requires a catalyst such as metal ions to initiate reaction

Ozone Antimicrobial Action

Ozone is an effective biocide against:
  • Virus
  • Bacteria
  • Bio-Film
  • Fungi (including mold and yeast)
  • Protozoa and many unicellular organisms
  • Other higher life forms such as small insects, worms, mites, and parasites
Its action can be compared to a broad spectrum antibiotic and its no wonder that Ozone is also know as a broad spectrum disinfectant

The advantage of ozone is also that apart from its anti microbial actions, it also exhibits simultaneous oxidation properties that is most suited for water treatment process

How is ozone produced: Two known methods are recognized

Ultraviolet (Light Energy) Technology - This is how ozone is produced via the sun's ultraviolet rays. This generates low ozone amounts used only for air treatment and not suitable for other applications .The concentrations are too low for microbial actions in water but enough in air.

Corona Discharge (Electrical Energy) - This is how ozone is produced via lightning. Large scale production of ozone requires this method. This is relatively more complex, with high output concentrations mainly used for Commercial and industrial applications.
  • Oxygen molecules (O2) are split by high voltage electrodes resulting in two        individual oxygen atoms (O1).
  • Oxygen atoms (O1) + (O1) unite with other oxygen molecules (O2) to produce        OZONE (O3).
  • Hence: (O1) + (O2) = (O3):

Advantages of Ozone

Ozone is the highly excited state of oxygen - the essence of life on planet earth. It decays naturally to oxygen and this makes it the preferred choice for a multiplicity of air and water treatment applications.

It is also the most efficient broad spectrum microbiological control agent and the fastest oxidizing agent available. It is also an excellent viral deactivating agent.

Ozonation of water is now accepted worldwide as the most efficient and nature friendly process to purify water. USFDA has certified ozone as GRAS (Generally Recommended As Safe).

Powerful ! More than 3000 times powerful than chlorine.

Safe ! Leaves no by-products; unlike chlorine which forms carcinogenic compounds (THMs) with organic compounds.

Predictable! More predictable than UV sterilization or chlorination.

Other benefits ! The decolorizing and deodorizing properties of ozone make water sparkling clear. Water stays fresh longer. These properties are also used in industrial applications and as color / odor removal of effluents


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