Please read information below and case studies.

Troxyen: Ozone in cooling towers Ozone is a strong disinfectant and an interesting alternative for the chemical biocides in cooling tower water treatment. The use of ozone in cooling towers has some great advantages. Ozone is one of the most powerful oxidants known to man. It's capabilities have been recognized for over 100 years.  It is used extensively in the purification of water throughout the world. Conventional cooling towers use chemically treated water that is run through the pipes and components of the tower.  This chemically treated water, however, is simply not enough to counteract the harmful effects of wasteful runoff, the buildup of bio-film, scale, and potential health hazards inherent in less than sanitary environments of cooling towers, in their current state. Ozone use has grown consistently in North America throughout the 80’s & 90’s. There are now over 250 water treatment systems in operation on the continent. It should be noted that the power of ozone is often used to treat both drinking water and waste water in many different applications. The objective of ozone use with cooling towers is to maintain the higher purity of recirculating water, better heat transfer, and a reduction of water waste and chemical use.

Implementation and Post-Implementation Experience

The ozone system installed at the Utility Annex has a generation capacity of 600 gr/hr. For comparative purposes, the actual costs and savings reported by Tierney and Mott are identified in Table 3. The overall savings was determined to be $100,012/year. Experience at the Utility Annex cooling towers has shown that ozone treatment is indeed a viable water treatment method for cooling towers. The idea that zero blowdown can be practiced is not feasible, since the calcium levels will eventually get too high and scale will form. At 60 to 80 cycles, the cooling towers were 60% plugged with scale in 8 months. In addition, the ozone injection circuit was plagued by the same problem and was difficult to keep on line. This forced the operators to reduce the concentration cycles between 10 and 20. Research indicated that they could increase the concentration cycles between 30 and 40, which is where they are now.

Table 3. Reported^(a) Cooling Tower Operating Information

Ozone is a powerful biocide causing viruses to deactivate and oxidizes many organic and inorganic substances. These properties have made ozone an effective chemical for water treatment for nearly a century. 

CASE STUDY

This case study concerns a system of two cooling towers with a capacity of 300 tons each, located at the Lockheed Martin Electronics and Missiles Ocala Operation in Ocala, Florida. Data were taken from a paper written and presented at the DOE Pollution Prevention Conference XI in Knoxville, Tennessee, on May 16, 1995 (See "Who Is Using the Technology" for a contact at Lockheed Martin).

The Lockheed Martin Electronics and Missiles Ocala Operation is responsible for the production of electronic assemblies, printed circuit boards, and wiring harnesses for space exploration, defense weapon systems, and defense communication systems. The cooling towers support a variety of test and production equipment and also support secondary cooling of HVAC systems.

The cooling tower system consists of two conventional Marley counterflow cooling towers with an operating capacity of 500 gallons each. The towers operate with an influent water temperature of 85°F (29.4°C) and an effluent temperature of approximately 75°F (23.8°C), for an overall temperature drop of 10°F (5.6°C). The facility was not connected to a public works wastewater treatment facility, so the blowdown water had to be transported offsite for disposal, at an annual cost of $45,360.

The cooling towers had an annual make-up water volume of 2.482 million gallons. Since the installation was not connected to an outside water source, the source of make-up water was treated wastewater recycled from the manufacturing process. This make-up water had a total organic carbon (TOC) content that was greater than 1500 ppm. This high TOC concentration resulted in a large chemical demand in treating the cooling tower water, which was reflected in the overall chemical treatment costs. The water was soft (~=50 ppm as CaCO₃) and contained ferrous sulfate from the manufacturing process. Poor system control resulted in either excessive chemical use or insufficient chemical feed, with subsequent scale formation requiring acid cleaning. The tower required acid cleans several times a year and the chiller condensers were cleaned at least twice during the summer months due to biofilm growth that resulted in excessive pressure head.

The existing multi-chemical treatment program consisted of the application of chlorine gas, additional biocides, and corrosion inhibitors. The total annual chemical costs were $24,733.

The savings data identified in Table 4 were generated by personnel in charge of system operation. Significant savings were achieved in all elements of the process: labor, energy, chemical, and blowdown disposal.

Table 4. Operating Cost Comparison for Cooling Water System Per Year

Savings with ozone treatment were $140,753/year with an NPV of $1,072,235 and an SIR of 31.9.

In this situation, prior to the installation of the ozone system, the costs and maintenance were high enough to cause the facility to examine alternative methods for cooling tower water treatment. The result was a decision to use ozone for the treatment of the water. A proposal from REZ-TEK International, Inc. was obtained in 1993 for the installation.


During the last 20 years, technological improvements have made smaller-scale, stand-alone commercial ozone generators both economical, feasible, and reliable. Using ozone to treat cooling tower water is a relatively new practice; however, its market share is growing as a result of water and energy savings and environmental benefits relative to traditional chemical treatment processes. 

Our improved patented process along with some of "trade secrets", runs even more efficient than any standard chemically operated cooling towers.


The information below is from The Federal Technology Alert on Ozone Treatment in Cooling Towers: 

The bacterial count was reduced three orders-of-magnitude, from one million to one thousand colony-forming units (CFUs), and blowdown waste was reduced 90%. The operator reported that no chemicals had been added to the cooling tower one year after the ozone system was installed.

Labor savings were reported qualitatively: "Maintenance operator was enabled to alternate one chiller and remove waste heat from air conditioning and test chambers. System has allowed the maintenance operator time to focus on the other facility issues." An important aspect of this type of savings is that it will free up maintenance staff to address other operation and maintenance issues at the facility.

Corrosion tests indicated that copper in the tower neither corroded nor pitted, while iron showed 2.0 mils per year of corrosion and 0.37 mils per year of pitting. It was reported that the corrosion effect of ozone was 50% of that of chlorine treatment.

The power consumption was reduced by 39%.

The findings of the case study were very positive one year after installation. 

If we could save you even 20%-30% of your operation cost would you be interested?

Consider how this money could go to other uses in your company. 

From this data and our experience you can see that your system can operate at a highier efficiency with less water and chemical usuage. 

We look forward to helping you save money And Go Green!!