Industrial cooling towers—the larger, more powerful version of HVAC systems found in office buildings, schools, and hospitals—are used to remove heat from cooling systems found in industrial environments. Cooling towers are typically employed in:
- Electric generating plants
- Pulp and paper mills
- Chemical manufacturing plants
- Iron and steel manufacturing
- Petroleum refineries
- Food processing
- Aluminum manufacturing plants
Understanding the Risks
But while cooling towers provide a cost-effective and energy efficient method of removing heat in industrial processes and environments, they can also become a source of additional risk for the team charged with managing them and potentially, their surroundings.
There are several types of risk that cooling towers present, from physical threats such as slip/fall hazards to personnel, overflow/flooding damage, or electrical hazards brought on by the presence of water. However, the water itself—or rather what’s found in it—is its own area of concern. Let’s focus on this water-borne risk and, more importantly, how to manage it properly.
A key consideration for teams that manage industrial cooling towers is the risk that comes from Legionella —a bacteria that can cause a serious lung infection or pneumonia known as Legionnaires’ Disease. People get Legionnaires’ by directly breathing in airborne water droplets containing Legionella bacteria (it’s not transmitted person-to-person). That means that facilities that don’t monitor or check for Legionella could be creating hazardous conditions for both workers at the facility and those who live in surrounding areas.
Turns out that Legionella bacteria love cooling tower water. Why? Because these systems present the perfect environment for microbial: pools of warm water that are open and exposed to the atmosphere.
Without proper testing, cleaning, and/or disinfected through regular maintenance, contamination risk is more “when” than “if”. In fact, over the past handful of years alone there have been multiple Legionnaires' disease outbreaks traced back (or considered the highly-like source of infection) to contaminated industrial cooling towers in Scotland and France leaving nearly 200 people sick with 21 fatalities. 
How Flow Cytometry Can Help Industrial Cooling Towers Monitor Bacteria
Now that we know Legionella bacteria—and the associated risk of Legionnaire’s Disease—can thrive in industrial cooling tower water, let’s talk about the best way to monitor for contamination, the first step in managing risk.
Unfortunately, the most common microbial testing methods are based on cell cultivation—that is growing cells on agar plates or in liquid culture media—only capture a fraction of the microbial population or resort to unprecise proxy parameters to assess the microbial load in a sample. As a result, this testing method provides a limited picture of what’s in the water.
A key reason the cultivation model fails comes from something called VBNC stands for “Viable but non-Culturable” bacteria. These are bacteria that are alive and able to perform certain functions but still do not grow and multiply in the laboratory using standard culturing techniques, hence easily overlooked. This is especially problematic because VBNC bacteria can remain infectious and cause disease, and therefore continue to be a threat to humans or animals.
Thankfully there’s a better method to identify, and even count, bacteria, called Flow Cytometry. FCM uses optical technology for electronic cell counting that allows multiparametric analysis of the properties of thousands of cells per second.
It works like this: Cells which have been labelled with a fluorescent dye pass in front of a laser in a confined stream of fluid. The laser excites electrons in the fluorescent dye that then return in fractions of a second to their previous state by emitting light. The analog light signal gets transformed into digital data that is further processed into the desired format of the user.
A major advantages of FCM is the ability to analyze a very large number of cells quickly and accurately. This is especially true when compared to cell cultivation. FCM is quite sensitive and can provide substantially more insight into water microbiology than the competing methods. FCM started off in the 1970s and has since become a routine tool in in-vitro diagnostics and life sciences research and pharma. Up until recently, however, widespread adoption of FCM outside of these applications has been hindered by:
- The complexity of the method
- The maintenance requirements of the equipment
- The technical/scientific requirements towards the operator
The Bottom Line: FCM is Now Available for Routine Use. By Anyone. At Any Time.
Through extensive development work, rqmicro has succeeded in greatly simplifying and automating FCM. Now you can bring the accuracy, speed, and versatility of FCM water testing into other industrial use cases, such as cooling towers. With rqmicro.COUNT, industrial cooling tower operators have a tool that can help them quickly and efficiently quantify bacteria such as Legionella using flow cytometry. This monitoring approach allows for several key benefits including:
- Accuracy: High measuring accuracy and sensitivity on single-cell level
- Speed: First results are available within 30 minutes
- Versatility: Test kits available for unspecific counting of all bacteria and also specific counting of pathogens (E. coli, Legionella) on the same platform
- Cloud-Connected Data: Share data with secure cloud platforms for automated analysis, alarms and sharing of reports from the dashboard
- Simplicity: Ready-to-use reagent tubes and single-use cartridges make flow cytometry as convenient as never before
 "Edinburgh Legionnaires' outbreak: Third death reported", BBC online, July 3, 2012, https://www.bbc.com/news/uk-scotland-18693873
"A Community-Wide Outbreak of Legionnaires Disease Linked to Industrial Cooling Towers—How Far Can Contaminated Aerosols Spread?", IDSA Journal Article, 2006, https://academic.oup.com/jid/article/193/1/102/863674