Case Study: Remove and Prevent Biofilms in Cooling Towers

This case study was recently published in the Facilities Engineering Journal. Cooling towers are very active at rejecting process heat and therefore are still one of the most environmentally friendly ways to provide process cooling. However, there are still challenges for cooling tower operators to reduce costs and ensure compliance with local regulations for the control of Legionella bacteria.

Some of these challenges are increasing water costs, process efficiency challenges, process fouling and rising maintenance costs which all need consideration while ensuring regulatory compliance.

Most of these challenges are avoided with effective water treatment of the system. Typically, chemical and non-chemical programs use corrosion inhibitors, antiscalants, bio-dispersants and biocides to provide stable waterside conditions.

Conditions vary in cooling systems with process load changes, process contamination and breakdowns leading to challenges in water chemistry control. All of these factors increase the risk of biofilm formation in a system, and once accumulated, it is tough to remove and provides the ideal habitat for pathogens such as Legionella bacteria to reproduce. Biofilms act as insulating barriers for heat transfer, reducing the efficiency of a system significantly and provide conditions for microbiologically induced corrosion.

A trial, using Bio-organic catalyst (BOC) technology on a variety of industrial and commercial cooling towers. Typically, the BOC replaces secondary biocide dosing or traditional bio dispersant dosing and therefore is no extra cost to the overall program. It is, however, non-toxic and environmentally friendly and thus reduces the health and safety impact for employees handling chemicals on site.