Cooling towers use water as a circulating coolant, which absorbs heat from a system and releases it into the atmosphere to have the system cooled. The cooling water in a cooling tower will be recycled through the system. However, the circulating cooling water provides suitable temperature and humidity conditions for the growth of bacteria and microorganisms. And microbial growth can lead to problems such as sediment attachment, equipment corrosion, and algae blooms. This will lead to blockages in pipes and, more troubling, to bacteria such as Legionella, which can cause serious health concerns. The good news is that cooling tower ozone sterilization is now the best solution for the problem.
For the treatment of circulating water in cooling towers, chlorine preparations or organic biocides at low costs were generally applied in the past. These solutions may have great impacts on the environment. Chlorine agents and organic biocides cannot effectively inhibit resistant bacteria but will add toxins and make the water more corrosive. In the face of this problem, in recent years, as a better solution, cooling tower ozone sterilization has gradually been widely recognized and adopted.
How Does Ozone Work?
The use of ozone in cooling towers was encouraged by the gradual limitation of chlorine sterilization of circulating water in the late 1970s when the U.S. Environmental Protection Agency (EPA) found that chlorination of water produced a variety of carcinogenic organics. As a strong oxidant, ozone has many advantages. Ozone has a strong sterilization ability, which is also simple in practical operation. Ozone treatment does not change the pH value of the water or cause any secondary pollution. The application of ozone in cooling water treatment is mainly shown in the following aspects:
1. Ozone can prevent the formation of scales
The scale in the circulating water of a cooling tower is formed from the concentration and crystallization of salt substances in the water. By introducing ozone into the water, the cooling water can be guaranteed to be free of scale at a total dissolved solids of 1600mg/L and a hardness of 710mg/L. This is impossible for those ordinary scale inhibitors. According to an analysis, the significant effect of ozone is due to its ability to move carbonates towards bicarbonates. Therefore, the ozone sterilization of cooling tower has a significant advantage over other scale inhibitors.
2. Ozone can prevent the corrosion of metals
Ozone, as a strong oxidant, was once considered corrosive. However, recent studies have shown that ozone has a very good prevention of metal corrosion. This is because the oxygen atoms generated after ozone decomposition can react with ferrous ions. The reaction will form a passivation film on the surface of the positive electrode, thus playing a good role in protecting the metal from corrosion. Tests have shown that ozone can reduce the corrosion rate of steel by 1/3 to 1/2.
3. Ozone’s killing effect on bacteria, viruses and microorganisms
Ozone is a recognized pollution-free biocide. Ozone at 0.1 PPM can effectively kill bacteria and viruses, and control the growth of microorganisms in circulating water in cooling towers. Ozone also oxidizes the organic composition of the dirt that has formed, making the dirt loose and easy to be removed. Cooling tower ozone sterilization can effectively control the growth of microorganisms and also reduce the difficulty of daily cleaning and maintenance of cooling towers.
According to statistics, cooling tower ozone sterilization can reduce about 50% of the sewage discharge and slow down the corrosion rate of metal also at about 50%. By ozone descaling, the equipment can save energy up to about 15% and the compressor performance can be improved by over 5%. From an economic point of view, using ozone can reduce costs by more than 50% compared to using traditional water treatment methods.
Operation Method for Cooling Tower Ozone Sterilization
The method of applying ozone in the circulating water of a cooling tower is not complicated. It can be done by introducing the ozone generated by an ozone generator into the water to be treated. The concentration of ozone can be monitored and controlled with the help from a manual ozone test kit or meter.
In our previous Blog posts, we talked about the significant role of ozone in removing kitchen odors, car odor, smoke smell, and many other kinds of odors. We have also discussed the advantages of ozone in water treatment industry, its use in aquariums, swimming pools, and in the production of bottled water. You can read them by checking out our Blog. As a gas with strong oxidizing ability, the field in which ozone can function is impossible to define. Its application scope will continue to expand with the development of the present industries, the advancement of technology and the emergence of new industries.