Buildings provide a hospitable environment for a range of bacteria, which are found on surfaces, air and water. Water-borne bacteria originate from the outside in small quantities, and remain harmless as long as they don't become established. Once colonies form their numbers increase geometrically and some species can cause harm to people and equipment. Considerable efforts are taken to prevent harmful bacteria from making contact with building occupants and visitors. Frequent testing programs, cleaning regimes and biocides in water systems help to maintain low levels of biological organisms.
Cooling towers play a prominent role in airborne bacteria control, since open loop systems are exposed to weather and outside elements. Dirt, pollen and debris to enter the water stream by the wind, and they circulate throughout the system until they are physically removed or become sediments. Suspended particles and biologic matter are ideal hosts for the formation of biofilm (also known as bioslime) that provides favorable conditions for a range of microorganisms to become established.
Biofilm Supports Pathogens
Facility engineers and operations managers are aware of waterborne pathogen control and testing procedures, that can be found in cooling towers, boilers, and potable water systems. ASHRAE’s recently issued Standard 188 provides minimum Legionellosis risk management requirements for building water systems for reducing risk due to Legionella bacteria that can become airborne and inhaled by humans near an infected water system.
Biofilms form on suspended particles, smooth or limescale surfaces and can be prevalent in any structure, including efficient and LEED certified buildings. When disturbed or oxidized by chemical biocides, the production of biofilm increases rapidly, and some portions break away and drift through the water stream to attach in other locations where new colonies will establish and create more biofilm.
Chemical treatments play a central role in bio control, though this isn’t enough. The favorable conditions that host bacteria growth must be eliminated. Bacteria are surprisingly resilient, with ability to rebound to prior colony sizes within weeks after biocides reduced counts by 99.99%. Physically removing biofilm is important for maintaining control of bacteria and pathogens in water systems.
Biofilm Control in Cooling towers
Biofilm is a common issue for cooling tower water system operators as it is difficult to control with only chemicals, so physical removal is required. According to OSHA, cooling towers and evaporative condensers should be inspected and thoroughly cleaned at least twice per year.
Biofilm is actually a consortium of various microorganisms that stick to each other and to a surface or sediments. The bacteria jointly produce a slime that they live beneath, which protects them from predators, temperature changes and biocides. Biofilms are quite resistant to biocides, so increasing the amount of biocide in the water stream is usually not enough to disinfect a cooling tower.
Biofilm contains a range of potentially harmful organisms that include pathogens like Legionella, and sulfite reducing bacteria that can cause significant corrosion in your HVAC system. A thin layer of biofilm impedes heat transfer more than scale deposition does; wasting significant amounts of energy.
Legionella occurs naturally and will not become established without a host environment like a biofilm that offers not only protection, but contains organisms that nourishes them. Once established beneath a biofilm layer, Legionella are difficult to eradicate. Removing biofilm is as important as dosing with biocides.
Removing Biofilm with Physical Water Conditioning
Physical Water Conditioning effectively removes biofilm and floating bacteria beyond what chemical dosing achieves, by causing biofilm to detach from surfaces. HydroFLOW uses a pulsed frequency that extends throughout the entire water system. Unlike magnets and wrapped pipes that only have local effect where a device is installed, the patented Hydropath signal reaches slow-moving water zones and dead legs where bacteria are prevalent, and where chemicals can’t access. The frequency irritates biofilm, causing it to detach anywhere in a water system.
The HydroFLOW frequency operates 24/7 throughout the water system, and disturbs bacteria and biofilm by injuring cells and causing individual bacteria to rupture. Biofilm is dislodged and is removed by the side stream filter. The absence of biofilm prevents new bacteria from being established, and Total Bacteria counts remain in low numbers.
Biocides are Enhanced by HydroFLOW and Filtration
HydroFLOW can reduce the volume of chemicals by up to 75%, though biocides remain an important component of water system management. It is important to maintain biocides in case a bird or large organic load enters the water and causes a spike in bacteria. HydroFLOW and side stream filtration enhance biocide effectiveness because the dislodged biofilm and suspended particles are removed by the filter, which decreases the amount of organic matter that would otherwise deplete a biocide quickly. The biocide lasts longer and is more effectivly applied to free floating organisms.
Incorporating HydroFLOW with filtration and biocide significantly prevents biological fouling and corrosion in a cooling tower system. HydroFLOW is an effective secondary biological control while preventing scale accumulation throughout a water system.
HydroTech provides eco-friendly, solid time release biocides that are effective without relying on hazardous chemical drums, manifesting and disposal.
Total Water Management Controls Biofilm, Scale and Conserves Water
HydroTech Solutions provides the Total Water Management program for cooling tower systems that includes:
- HydroFLOW physical water conditioning
- Solid chemical biocides and corrosion inhibitors that are eco-friendly
- IoT-enabled water sensors and meters
- Data analysis with a secure dashboard 24/7 on a phone or desktop
- Monthly site visit by a qualified technician who reviews system components and water chemistry and periodically collects water samples for biological testing
- Monthly reports for individual buildings and portfolios detailing water use, observations, and cost details.
The Total Water Management program maintains low biological levels in cooling tower systems, which controls pathogens, microbial induced corrosion (MIC) and improves energy use by preventing biofilm from insulating heat transfer surfaces.
- Asset life cycles are extended
- Operating budgets are reduced
- Maintenance events are reduced
- Predictive analytics anticipates equipment failures and inefficiencies across your portfolio of locations
The Total Water Management program provides operating data and automated analysis that measures water use, conservation, cost and system efficiency. The program costs you nothing to install, and pays for itself through cost savings.