Beginning in October 2016, AS Filtration, LLC conducted a year-long study to document the effectiveness of a non-oxidizing biocide within a side stream filter on the cooling tower system of a four-story office building in Chattanooga, Tennessee. AS Filtration installed an Aqua-Stream™ side stream filter, utilizing their unique Pathex® antimicrobial filter media, on the 400-ton cooling tower system in operation at the office building. The goal of this study was to analyze the effects of the Aqua-Stream™ and Pathex® on bacteria, energy use, water use, and overall equipment/maintenance costs.
The Aqua-Stream™ side stream filter, using Pathex® antimicrobial filter media, proved successful during the year-long study in Chattanooga. The goal of a side stream filter on a cooling tower is to treat the water in such a way that operation is more efficient, both financially and in terms of cooling effectiveness. Bacterial presence in the Chattanooga cooling system was consistently lowered throughout the year to levels significantly below industry standards, commonly exceeding the performance demanded by the cooling industry. As the presence of bacteria encourages the proliferation of other concerns like scaling, fouling, and microbiologically influenced corrosion, its removal results in improved operational efficiency (PNNL 2012). Additionally, the removal of chlorine chemical treatment for the year suspended the corrosive action of oxidizing biocide treatments. The negative environmental impacts of chemical use were also halted. Finally, the financial savings from the use of a side stream filter were estimated to be $10,646 per year, including a savings of approximately 228,000 gallons of water, using the Pacific Northwest National Laboratory formula for a comparable, properly maintained 400-ton cooling tower.
The use of the Aqua-Stream™ side stream filter and Pathex® antimicrobial filter media from AS Filtration™ successfully controlled waterborne bacteria and provided exceedingly beneficial results for the year-long study in Chattanooga. The side stream filtration system would reasonably be expected to continue to improve the condition and operation of the cooling tower system, with minimal maintenance requirements. Several side stream filters utilizing Pathex® have been in continual operation for nearly a decade, with proper maintenance and backwashing, and continue to operate as designed for the control of bacteria in cooling systems. Given the proven benefits of the Aqua-Stream™ side stream filter with Pathex® antimicrobial filter media, its continued use on the Chattanooga cooling tower system would result in ongoing financial savings and improved operational efficiency for many years to come.