Why do cooling towers promote bacterial growth?
Simply stated – the combination of sunlight, air, warm temperatures, and nutrients are a perfect recipe for bacterial growth, making cooling towers an ideal breeding ground for bacteria.
Biocides are expensive – are they worth it?
Here is an example of worst-case scenario. Given the rising rate of legionella outbreaks in the U.S. and its associated harm, personal injury claims and litigation are becoming more frequent. Public health notices and negative media attention can also lead to business interruption and reputation damage.
One example took place in 2016 in Hopkins, MN where 23 people got sick with Legionnaires' disease and one person died. Samples were taken from all cooling towers in the area and sent to a lab in New York for testing. When the results came back, the source was found to be the cooling tower at a beverage processing plant. Unfortunately, there are many other examples of legionella outbreaks in the U.S. and globally.
In addition to an increased risk for Legionella, leaving a system unprotected from biological growth can lead to more common problems found in systems:
- System fouling
- Increased energy costs
- Expensive clean-up
- Under deposit corrosion from biofilm
- Plugged pipes, orrifices, valve, heat exchangers, etc
- Reduced flow rates
- Unsightly algae, fungi or bacteria growth
How to prevent biofouling.
A comprehensive and well-maintained water treatment program that includes biocides can prevent biofouling. When it comes to cooling tower maintenance the benefits really outweigh the costs. It is important to have a program that relies on the right biocides. It is equally important to have a Water Management Plan
to ensure there is an ongoing process of evaluation and remediation to verify your system is healthy. The water in your system is literally a moving target and regular testing is an important part of the process. Preventing serious issues such as positive Legionella results is key, but knowing how to respond in the event your system does test positive is even more important.
How can I check if my biocide program is working?
There are several ways to check the effectiveness of a biocide treatment program. The testing options vary in terms of cost and timing that it takes to get results. Below are some options to verify and validate that your system is healthy:
ATP UltraSnap®: This is a personal favorite because you get an instant result – expensive upfront costs, moderate costs per test. Real-Time Data.
Agar Panels: 2-3 day incubation period – most common, fairly inexpensive, but after 3 days is your cooling tower water still in the condition it was in at time of test?
Mesh Biofilm Coupons: The mesh creates an artificial landing spot for potential bacteria fouling and an easy way to monitor results. Good for analyzing fouling potential and for gauging effectiveness of a cleaning procedure. The mesh biofilm coupon is similar in size to typical corrosion coupons and can be placed in a standard corrosion-coupon rack.
- Check the screen above the return drain and clean if necessary to ensure proper flow.
- Feel along the side walls at the water-line for any slime or biofilm.
- Inspect the tower basin for sediment that can harbor bacteria and cause under-deposit corrosion.
- Make sure the tower make-up and level controls are functioning properly and that there is no tower water continuously overflowing out of the overflow drain which diminishes biocide performance.
- Inspect mist eliminators for scale or algae.
Keep a log of your chiller’s approach temperatures – any increase in the differential could be related to bacteria growth and/or scale formation.
What if a biocide is not effective at reducing high bacteria counts?
If your system tests positive for bacteria, knowing the specific bacteria you are encountering can be a game changer!
BART biodetectors are excellent diagnostic tools to help identify the presence of process disruptors. Find out if you have bacteria creating slime layers, limiting biocide effectiveness, or discover if iron-reducing bacteria are eating your pipes.
Do you have questions about your cooling system?
Each cooling system has unique challenges and opportunities. Watertech has a proven track-record with developing Water Management Plans for our customers to keep their facilities safe and in compliance. Would you like a system evaluation? Click the link below and fill out the form. One of our Technical Engineers will be in touch.
Ed Dimler, Territory Manager - Iowa
Ed has worked in the water treatment industry for 31 years and has experience in boiler, cooling and wastewater chemical treatment programs. Ed leads educational training events and seminars to promote better water management and improve safety. He is a member of ISHE and holds a BA from St Mary's College.
Contact him directly at 563-419-8106, firstname.lastname@example.org
or follow him on LinkedIn.