Ozone as a cooling tower biocide is not only environmentally benign, it also brings a significant number of other benefits.
The circulating water of cooling tower systems has always been an ideal place for growth of microorganisms. The warm temperature of the water and the addition of nutrients from the scrubbed air flowing through the tower provide a virtual nirvana for all sorts of microbes and algae. In turn, these organisms multiply at fantastic rates. The result is degraded system efficiency due to blockage of flow, shortened equipment life due to corrosion, increased operating cost due to higher pumping power requirements, and the spread of disease or even death
Ozone as a cooling tower biocide offers a means to this end. It is not only environmentally benign, but ozone use also brings a significant number of other benefits to the cooling tower system operator. Ozone is a practical oxidizing biocide because it is the fastest acting and the most efficient oxidizing agent against all microbiological organisms - when properly applied, ozone will kill all viruses, bacterium, cysts, and algal species. And, any ozone not consumed as a biocide naturally decays to oxygen, making ozonation the preferred choice for biological control of many cooling tower systems.
Field tests have demonstrated that the use of ozone in place of chemical treatment can reduce the need for blowdown, and, in some cases where make-up water and ambient air are relatively clean, can eliminate it. As a result, cost savings accrue from decreased chemical and water use requirements and from a reduction of wastewater volume. There are also environmental benefits as fewer chlorine or chlorinated compounds and other chemicals are discharged. There is also a belief within the industry (and some evidence) that under certain conditions ozone acts as a descaling agent. The premise is that ozone oxidizes the biofilm that serves as a binding agent adhering scale to heat exchange surfaces. When scale buildup on condenser tubes is reduced, higher heat transfer rates are achieved. Increasing the condenser heat transfer rate will reduce the chiller head pressure, which then allows the chiller to operate more efficiently and consume less energy.
Biological growth, scaling, and corrosion are the main maintenance concerns with these cooling towers.