A versatile broad-spectrum microbiocide, chlorine dioxide is well known for its effectiveness in controlling a host of microorganisms that grow in cooling water systems. Fungi, algae and bacteria flourish in conditions that don’t favor chlorine or other organic-based proprietary products. However, Verox-8, a concentrated solution of stabilized chlorine dioxide, is being used with favorable results as a control for microbiologic growth in water treatment systems, and in particular, under conditions not favorable to chlorine dioxide.
Controlling Microbiologic Growth in Open and Closed Systems
Despite regular treatments of various products to control microbiological growth, slime deposits can persist in troublesome ways in cooling systems. Typically, slime may be seen in a cooling tower’s louvers, sump basins or distribution decks, or other locations that are even more worrisome, such as distribution piping or the condensers’ tubes and/or tube sheets. When this condition occurs, frequent cleaning is necessary, or high corrosion rates can occur and damage the refrigeration equipment.
Slime bacteria excrete protective polysaccharide film, which traps solids in the water, which then form deposits that are hard to get rid of in cooling systems. These deposits are also acidic: they corrode underlying metal surfaces. Slime also shields live bacteria from a number of microbiocides, so that they continue to grow in the water. It’s a tough situation to correct.
What’s more, slime deposits have insulating properties that not only reduce heat transfer but restrict water flow, reducing the effectiveness of the refrigeration process, and driving up operating costs.
Even more alarming is that studies show slime deposits pose health concerns, in that they can promote environments in cooling systems conducive to Legionella pneumophila, which leads to infection with Legionnaires Disease, a serious health issue.
The Verox-8 Advantage
Chlorine dioxide works by penetrating biofilm deposits and destroying the bacterial cells that secrete slime. Furthermore, chlorine dioxide is a selective oxidizer. It won’t degrade phosphanates, azoles or polymers crucial to water treatment; nor will it promote corrosion of steel or copper components.
Jamestown Technologies has used Verox-8 with good results in several projects where water treatment cooling systems had been compromised by microbiologic deposits, and where corrosion was also occurring. Verox-8 is Environmental Protection Agency-registered. As a single-drum microbiocide, it does not require complex activation equipment, nor do hazardous precursor chemicals need to be stored for its use. While traditional chlorine dioxide technology has been recognized as effective, it’s also been known to require significant maintenance and capital expenses, as well as heightened attention to plant safety and handling. Verox-8 provides the benefits of traditional chlorine dioxide technology, but not the problems.
In addition to performing well when there is persistent slime or biofilm, Verox-8 also is effective when systems have elevated pH levels or there is nitrogen or ammonia contamination, or when there is contamination from mineral or vegetable oils, as well as organic compounds that promote microbial growth.