What is ozone ?
Ozone, as a chemical constituent of the terrestrial atmosphere, has emerged when the first electrical discharges were generated high up, in the presence of oxygen. Even though the presence of ozone can be easily detected due to its specific smell, even in very small concentrations, its identification as a particular chemical constituent was performed by the German chemist Christian Friedrich Schönbein in 1840, who, after certain experiments in electrolysis systems and in the presence of electrical discharges, identified a compound with a specific smell, which was identical to the one detected during a storm, in the presence of intense lightning. The ‘ozone’ name comes from Greek, as it is the transcription of the verb ‘to smell’ (ozein - ὄζειν). The chemical identity of ozone (O3) was set up by Soret in 1865.
Even though technology has tremendously progressed in the past 150 years, the main methods for producing ozone are still based on the utilisation of the electrical discharges to which a flow of gas containing oxygen is subjected in a space between two surfaces loaded to an electric potential (electrodes). Under the action of the intense local electrical field, the molecule of oxygen (O2) is divided into two atoms of oxygen (O), which instantly form a connection with another molecule of oxygen (O2), the result thereof being the creation of the molecule of ozone (O3).
•1840 - Schönbein identifies the specific smell of ozone and terms it according to the Greek word.
•1850 - Werner von Siemens builds the first industrial ozone generator.
•1865 - Jacques-Louis Soret determines the chemical formula of ozone (O3).
•1893 - One makes the first real scale system for the water treatment, in Oudtshoorn, The Netherlands.
•1903 - The first plant of treating water by ozone – at the Niagara Falls, The United States
•1905 - The commissioning of the water treatment plant in Nice, France, thought to be ‘the birthplace’ for the industrial applications of ozone
•1909 - The first application of ozone as an agent for preserving meat products (Germany)
•1914 - The German army uses gaseous ozone to fight infections.
•1915 - The German physician Albert Wolf uses gaseous ozone to treat skin disorders.
•1939 - Ozone is used to prevent the development of the microorganisms within vegetal product storing processes.
•1950 - Ozone begins to be used within water bottling technological processes.
•1965 - Ozone begins to be used for removing the colour from the treated drinkable water, in the UK.
- In Switzerland one implements applications as to the degradation of the phenol compounds and of the pesticides from the drinkable water.
•2001 - The US FDA (Food and Drug Administration) regulates the utilisation of ozone as a treating agent in the food field.
•2004 - Ozone is acknowledged as a treating agent and recommendations are set out as to its utilisation for processing natural juices (US-FDA).
Advantages of using ozone
• Ozone is one of the most powerful known oxidising and disinfecting agents, at present available for treatment both in the aqueous environment and in a gaseous form.
• Even though not completely soluble in water and relatively unstable (it decomposes itself), its disinfecting properties can be efficiently used to the fullest.
• As a result of its action, ozone decomposes itself into oxygen, thus enhancing the degree of oxygenating the environment.
• Ozone reacts with a wide range of organic compounds, bringing forth their oxidation.
• Even though ozone is the most powerful commercially available oxidising agent, its utilisation and handling can be made totally safely, owing to the fact that it is produced on site, in the dose and amount wished for, as it cannot be stored.
• Ozone by itself does not add additional byproducts to the treated medium.
• In gaseous form, ozone is a powerful agent for fighting smells, as it acts directly on their source and vectors (odorous gases).
• Ozone does not directly affect the pH of the treated environment.
• Within the processes of treating drinkable water, of treating domestic, industrial and secondary waste waters, apart from its great oxidising power, ozone has got the ability of generating the conversion of the organic compounds that are resistant to the biological processes of degradation into biodegradable compounds. The combination of the ozonisation processes with biological ones may increase the efficiency in eliminating the polluting compounds much more than in case of using individual processes.