Ozone Treatment in Cooling Tower Water

Spartan Environmental Technologies supplies industrial ozone generators and fully integrated ozone water treatment systems for cooling towers and cooling water treatment applications. Call Spartan for help selecting one of our turnkey packages.

Ozone Application and Treatment of Cooling Tower Water Overview

Industrial ozone generators have been used extensively for the treatment of cooling water. This is due to the fact that ozone is a powerful, but environmentally friendly biocide. Its effectiveness has been studied by the U.S. government and industrial water treatment companies (links below):

• Ozone effectiveness studied by the U.S. government: Federal Technology Alert on Ozone for Cooling Water Treatment
• Ozone effectiveness studied by industrial water treatment companies on the laboratory, pilot and commercial scale: Application of Ozone in Cooling Water Systems
• View or Download a shorter technical bulletin PDF: Ozone Cooling Water Treatment

The unimpeded growth of bacteria, algae, fungi and mussels in cooling circuits promotes the formation of deposits in pipes, heat exchangers and the internal parts of cooling towers. This can lead to a reduction of heat transfer efficiency, corrosion and in some cases, emissions of harmful pathogens such as legionella. In fact, ASHRAE has proposed regulations for controlling biological growth in cooling towers in order to minimize the potential for the growth and emission of legionella. Read a more detailed discussion on the need for cooling water treatment.

Ozone Technology Application in Cooling Tower Water

Ozone is a powerful biocide, which, when compared to organochlorine-based biocides, not only combats microbial growth processes but also continuously reduces organic impurities. These impurities, measured as COD and AOX, can be reduced to acceptable discharge levels. No undesirable secondary reactions or salt build-ups occur. Read a more detailed discussion on the effects of ozone in a cooling tower.

Ozone is produced in an ozone generator and usually injected continuously into the cooling water system in a branch stream. The microorganisms in the systems are thus under permanent attack and microorganism counts are held at a very low level. This also applies to the bio films in the systems, so the tendency for coatings to form is kept to a minimum. This means that intervals between overhauls and maintenance sessions can be extended. A residual ozone concentration of 0.1 to 0.2 ppm is typically effective in keeping the cooling tower and the cooling circuit clean.

Some suppliers of industrial ozone systems suggest that ozone can universally protect a cooling tower from microbiological films as well as scaling and corrosion problems with zero blow down. While there are examples of this type of operation, it is highly dependent on the water chemistry of the tower and makeup water. Spartan believes that there are situations when ozone should be used in conjunction with anti-scaling agents and corrosion inhibitors.

The chemical added to an ozone treated system needs to be compatible with ozone. Spartan supplies a chemical formation for ozone treated cooling towers should these additional materials be needed. In any event, before applying any treatment to a cooling tower the tower owner should consult with a professional industrial water treatment company that has analyzed the water chemistry.

Advantages of Ozone Treatment in Cooling Tower Water

There are many advantages of using ozone treatment in cooling tower water including:

• Low corrosion rates
• No persistent chemicals or disinfectants in bleed
• Ozone breaks down to oxygen
• In some cases, ozone can replace disinfectants as well as dispersant and inhibitors
• In many cases, a lower overall cost
• Effective in a wide pH range
• Effective against mussels

Considerations for Ozone Treatment in Cooling Towers

Ozone use in cooling towers requires consideration of the following factors:

• Makeup water with high hardness and COD levels is less suitable for ozone water treatment
• Dead spots in the circulation system need to be eliminated
• The temperature of the cooling water in which ozone is used should be limited to around 45°C
• Materials of construction should be compatible with ozone

Ask Spartan a question or request a quote for ozone treatment in cooling tower water.