Ozone also has another, and no less important, role to play in the protection of the environment and human health in agricultural regions: various pesticides are used to increase fruit and crop yield and protect them from plant diseases, however, the residues of these pesticides make their way into soil and groundwater, and partially also remain in fruits and vegetables, leading to chronic diseases. Ozone, especially in combination with other oxidants (H2O2, UV, H2O2/UV), acts as a degradation agent of pesticide residues stored in groundwater.

How does ozone treatment work?

A solution of ozone with a concentration of 2.5–3.5 mg/l is applied in the above cases in a foliar way. As a result of such treatment, plant diseases are eliminated, the quality of the product is improved and their storage time is extended by approximately two weeks.

In the food industry, harvested fruits, vegetables and berries go through several processes involving water, such as washing, freezing, and packaging. This, however, increases their chances of contamination by pathogens and micro-organisms, which constitutes a major problem in terms of food safety.

Therefore, in order to avoid such contamination, agricultural products are washed and disinfected with ozonated water or ozone gas. This method has proven to be effective in the case of several micro-organisms, such as Escherichia coli, Penicillium Italicum and P. digitatum. Ozone is a universal disinfectant that removes any unpleasant colours and odours from agricultural products, while also destroying mildew, fungi, bacteria, viruses and plankton. The deodorising effect of ozone is based on the oxidation of ketones, hydrocarbons, acids, sulphides, and nitrogen derivatives. In addition, ozone improves the quality markers of products, such as colour, odour, taste, and extends their shelf life.

Use of ozone in livestock, poultry and fish farming

In this industry, ozone can be useful in ensuring the necessary living conditions for the dairy herd, beef-cattle, sheep, pigs, rabbits, chickens and other animals in farms and breeding. The same problems are present in livestock and poultry farming almost everywhere: due to poor ventilation and a large number of animals, the air is contaminated with ammonia, hydrogen sulphide, carbon dioxide, methane, and other gaseous pollutants. Moreover, many diseases are airborne, e.g. fowl cholera (Pasteurella multocida), Avipoxvirus (avian pox), Salmonella, Staphylococcus, and infectious bronchitis.

When used as an aqueous solution (0.2–0.5 mgO3/l) or sprayed as a gas in safe concentrations of 0.1–0.2 ppm, ozone can significantly reduce microbial contamination in farms.

Decreased need for antibiotics

Pre-ozonation of drinking water has been proven to significantly improve the health of livestock. As a result, the need for antibiotics and pharmaceutical disinfectants was reduced by up to 90–95%. Compared to pharmaceutical preparations, ozone is a naturally occurring substance (trioxygen) that is broken down relatively quickly into oxygen. The half-life of ozone at 20 °C in natural freshwaters is approximately 20 minutes.

It also reduces heating costs!

Ozone has also proven effective in deodorising the air of farms and stables. Thanks to the use of ozone, the need for ventilation in winter is reduced, which helps save on heating costs.

Ozone can be used in fish farming in two ways: by enriching the freshwater supply with ozone (indirect) or by carefully adding ozone directly into the fish tank (direct). While the latter method is more effective (the increase in the weight measurements of fish was more pronounced), it is also more dangerous, as excessively high doses of ozone are lethal for fish. My good colleague, Associate Professor Lui Pikkov at the TTÜ Institute of Chemical Engineering, obtained interesting results in disinfecting (O3 or UV) and purifying the circulating water of fish farms (e.g. trout) from nitrogen compounds.

Ozone has several roles to play in fish farm tanks: it removes suspended solids and dissolved organic matter that cause stress in fish, in addition, it decreases the content of nitrite and ammonia, which are toxic to fish, and increases the growth of fish. With the use of ozone, the water consumption in fish farms was significantly reduced by one tonne per farmed fish, greatly influencing the cost-effectiveness of the company.

Therefore, the use of ozone in agriculture, livestock and fish farming has both direct and indirect (environmental) impacts: ozone can replace both medicinal products (e.g. antibiotics), plant protection products (i.e. pesticides) and chemical disinfectants, thereby preventing the contamination of soil and groundwater with the residues of said chemicals.

Why on earth are we not using it to improve our living environment?