Summary of Study:
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.

Bacteria:
As described in the previous entry, controlling bacterial and microbiological presence can help a cooling system operate more efficiently and limit other undesirable issues. A cooling system with bacterial concerns can also be a health issue, harboring pathogenic bacteria such as E. coli and Legionella. These particular bacteria have been known to cause sickness in humans, with Legionella (responsible for Legionnaires’ disease) having caused dozens of fatal infections in the US alone.

Frequently, oxidizing biocide chemicals such as chlorine, chlorine dioxide, and bromine are used to control biological activity. While typically effective, the chemicals are often hazardous to handle, must be constantly replenished, are harmful to the environment, and can accelerate corrosion within the system (GE 2013). The extensive corrosion seen in Images 1 and 2 occurred over only 8 years, the length of time that the cooling tower has been in service. Prior to the installation of the Aqua-Stream™, chlorine was being used to treat the cooling water at the Chattanooga study site. During the year-long study using the Aqua-Stream™ with Pathex® all chemical treatment was suspended. All water samples were taken and analyzed by an independent laboratory. As shown in Image 3, the concentration of waterborne bacteria increased dramatically once the chemical treatment was stopped in mid-October of 2016, quickly approaching the allowable threshold before the effects of filtration were seen.

The combination of the Aqua-Stream™ filter and Pathex® media maintained a reduced bacterial presence via biological control for the remainder of the study. It is worth noting that during the warmer spring and summer months (when the cooling system is being used the most and bacteria thrive) the Aqua-Stream™ with Pathex® consistently maintained cooling system bacteria levels considerably lower than industry standards. Filtration through Pathex® frequently achieved bacteria counts lower than 100 colonies per milliliter (col/mL), and achieved counts as low as 10 col/mL, one one-thousandth of the industry standards set by the Cooling Technology Institute (CTI 2008).

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 188 recommends water treatment plans for a building’s HVAC and water systems to address these issues. Though the standard itself does not have regulatory authority for pathogen control, it is frequently incorporated into building codes. These results demonstrate the suitability of the Aqua-Stream™ filter with Pathex® media as a critical component of a water management plan to meet or exceed the criteria set forth in ASHRAE Standard 188.

The next entry will focus on energy consumption and how it relates to cooling systems and side stream filtration. If you would like to know more or discuss using the AquaStream™ and/or Pathex® at your facility, please contact us!

Summary of Study:
Starting 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-StreamTM side stream filter, utilizing their unique Pathex® antimicrobial filter media, on the 400-ton cooling tower system in operation at the office building (Image 1). The goal of this study was to analyze the effects of the Aqua-StreamTM and Pathex® on bacteria, energy use, water use, and overall equipment/maintenance costs.

Overview:
Cooling towers are an important part of many large-scale cooling systems. They typically use evaporation to cool process water, so that the water can be reused to extract heat from the system. Given the purpose of cooling towers, they operate much more efficiently when their heat exchange surfaces are clean.

Cooling towers face four primary water treatment issues that can reduce operational efficiency: corrosion, scaling, fouling, and microbiological activity (PNNL 2012).

• Corrosion – can cause premature structural failures; exacerbated by high oxygen levels  and oxidizing biocide chemicals
• Scaling – precipitation of dissolved minerals; has insulating properties that reduce the efficiency of the heat exchange surfaces; requires more work from the system to achieve desired cooling
• Fouling – insulating film formation on heat exchange surfaces affecting performance and energy requirements of the cooling system; causes include process oils, suspended particles, and biologic growth
• Microbiological activity – can be either suspended or formed on system components; strongly insulating, increasing energy requirements; byproducts encourage further microbiological activity/growth     

All of these can negatively affect operational efficiency and are inter-related, such that an increase or decrease in the severity of one can cause a comparable, parallel change in the others (PNNL 2012). These water treatment issues arise for a number of reasons, including water chemistry, suspended and dissolved solids, dust, and bird and insect activity from the open system.

Multiple reputable studies, including several from the Department of Energy (DoE), have shown that side stream filtration can reduce the prevalence of the concerns described above. These studies also examined the benefits of side stream filtration on water usage, energy consumption, maintenance requirements/downtime, and biological control. Side stream filtration using the Aqua-StreamTM and Pathex® antimicrobial filter media allows for all of these benefits of filtration, with the addition of killing and controlling bacteria and biological activity. The Aqua-StreamTM selected for the cooling tower in this study measures 24 inches in diameter and roughly 80 inches in height, with a total footprint of 36 inches by 48 inches (12 ft2), and utilizes approximately 650 lbs (6.5 ft3) of Pathex® media. The filter operates with its own control system, virtually eliminating the need for any maintenance actions. Pathex® antimicrobial filter media does not degrade and is rejuvenated daily by the filter’s control system through a programmed backwash cycle.
 
The next entry will examine waterborne bacteria in cooling systems and the effect of Pathex® on these issues.

Whether your goals are to cut costs, reduce maintenance pressure on your staff, or do good for the planet, AS Filtration’s sustainable water treatment solutions are up to the task.
 
Here are 6 reasons why sustainable water treatment makes sense: 
 
1. Reduce chemical use
The leading water treatment solutions include chemicals for controlling bacteria, but those same chemicals also speed corrosion and scaling in pipes and tubes, shortening the lifespan of HVAC equipment, and, ironically, spurring the need for additional chemical treatments. 

2. Say good-bye to harmful byproducts
Water treatment chemicals, such as chlorine, can create hazardous disinfection byproducts that are considered harmful to humans and animals.  
 
3. Worker and facility safety
Some chemicals used in water treatment programs are explosive in high concentrations, and most are dangerous to handle and store requiring compliance with  special worker training as well as added material record keeping.

4. Decrease pressure on limited resources
Severe drought conditions over the last year underscored the need for clean water. Using sustainable water treatment products stretch the useful life of process equipment while reducing water and energy consumption.  

5. Financial savings
Saving water and energy translates directly into bottom-line savings. But the savings don’t stop there – decreased reliance on chemicals means less money spent buying, storing, and handling chemicals. And, choosing products that effectively clean and filter water without contributing to scaling and corrosion means your equipment will last longer and need less labor and downtime for maintenance. (Read more in our blog: 4 Ways to Save Big on Cooling Tower Costs). 

6. Get noticed
Local and national programs reward and recognize facilities that reduce their environmental impact through sustainable practices and products. AS Filtration’s products can help you earn LEED certification points and / or achieve ENERGY STAR certification. (Read more in our blog: Become an Energy Star). 

​Ready to go green with clean, blue water? Contact us today to find out how our sustainable water treatment solutions can solve your water woes and meet your budget goals.

The Federal Energy Management Program (FEMP) offers guidance for reducing water usage and improving water efficiency, and their Best Management Practices publication includes a section on cooling tower management. Although the FEMP resources are designed specifically for federal businesses and campuses, they’re best practices that can help all building owners and managers save money on cooling tower operations.
 
The FEMP’s best practice #10 offers water efficiency opportunities for cooling towers, and we’ll focus on three of those tips:

1. Maximize cycles of concentration
2. Install side-stream filtration
3. Consider alternative water treatment options

 
Cycles of concentration
Maximizing cycles of concentration reduces water lost through blowdown, thereby minimizing the amount of water needed as make-up water. Significant water savings can be achieved by running lengthier cycles, but using the same water for a longer period allows dissolved solids to accumulate between blowdown flushes, causing scaling and corrosion problems.  The extent of those problems is highly dependent on environmental factors and the quality of your makeup water.
 
The next two water efficiency recommendations, however, provide solutions for increasing cycles of concentration in new and retrofit configurations.
 
Side-stream filtration
Side-stream filters run continuously, filtering sediment from a portion of cooling water and returning clean water back into the system. This process prevents the buildup of scaling and biofilm and requires fewer maintenance interruptions. High-efficiency side-stream filtration also improves operational efficiency, saves water, and reduces the need for water treatment chemicals.

Learn more about high-efficiency side-stream filtration in “2-in-1 Solution for Industrial and Commercial Cooling Tower Water Treatment.”
 
Alternative water treatment options
The FEMP guideline here is a bit vague but refers to the fact that new treatment options can be effective tools in your arsenal for cutting chemical use and saving water. AS Filtration’s antimicrobial filter media, Pathex, is one such solution. Pathex is EPA-registered as a pesticide and is a proven tool for destroying waterborne bacteria on contact. The filter media enhances the efficacy of side-stream filters by removing not only suspended solids, but also by controlling bacteria as water is filtered. Pathex is a drop-in replacement for most sand and multi-media filters.
 
Our blog, How Clean is Your Water Filter?, compares water disinfection technologies and shows how Pathex filter media stacks up against traditional treatment options.
 
For more best practices in cooling tower management, read the FEMP’s full Best Management Practice #10.
 
To talk with an experienced engineer about your water efficiency needs, contact us.

Your cooling tower is home to hidden savings opportunities that significantly reduce energy and water consumption in your facility. Over time, patchwork repairs, general neglect, or changes in facility needs mean your cooling tower may not be operating in top form. Performing these 4 steps can keep your cooling tower working in tip-top shape, improving its reliability and extending its operating lifespan:

1. Catch problems early by tracking key parameters
A log is an early warning system for any developing problems with your equipment. By regularly checking and tracking the key components of your cooling tower, filters and treatment system, you’ll be able to quickly spot and address trends and outliers that may signal a looming problem. Catching those deviations early can help avoid costly maintenance and repairs down the road.

Cooling tower water treatment measures to track may include: water hardness, alkalinity, suspended solids, total dissolved solids (TDS), pH balance, chlorides, sulfates, silica, iron, manganese and ammonia.

2. Perform regular maintenance, like inspections and cleanings
In the case of your cooling tower, half an ounce of prevention may be worth a lot more than a pound of cure. Dirt, dust, pollen, algae, scale, fluctuating temperatures, process variations – any of these can add up to a quickly escalating problem if a cooling tower is left unchecked for too long.  Keep things humming along and avoid costly problems by regularly inspecting and tuning your equipment in accordance with its service plan.

Regular maintenance can help your facility reduce bleed-off, extend equipment lifespan, and keep operational and maintenance costs in check. It’s much cheaper to perform routine maintenance than to let a problem with your equipment or cooling water spiral out of control.

3. Use a filter to keep the system clean
The cleaner your system, the more efficiently it will operate. Although running higher cycles of concentration may save money on blowdown in the short term, that choice could be an expensive one in the long run if your water isn’t being filtered properly. Those higher cycles allow more suspended solids to accumulate in the water, leading to scaling, bio-fouling, corrosion, decreased heat efficiency transfer and higher energy costs.

Side-stream filtration devices, such as the Aqua-Stream, can remove even small (< 30 microns) suspended solids to permit high cycles of concentration without the build up of waterborne deposits. These systems continuously cycle a portion of your cooling water, reducing the need for system downtime, water treatment chemicals and maintenance hours. The Aqua-Stream requires 50% less backwash than other filters, further compounding savings.

By simply making the most use of the water in the system with adequate filtration and treatment, your facility can save money on makeup water, blowdown and associated sewer expenses.

4. Control biological growth
Cooling towers present the perfect conditions for biological activity thanks to their warm, moist environments. Biofilms are particularly problematic, as they have strong insulating properties, contribute to fouling and corrosion, and produce byproducts that further micro-biological growth.

Keeping biological activity in check has the added benefit of also minimizing the likelihood of scaling and corrosion. One method for controlling this growth is adding Pathex antibacterial filter media to your cooling tower water treatment plan. The silica media kills bacteria on contact without chemicals or harmful byproducts and provides protection for years. It’s a drop-in replacement for sand and multi-media filters that can deliver significant savings over the life of your cooling tower by reducing water, energy, maintenance and chemicals.

To save money on your HVAC system, look no further than your cooling tower. With these 4 steps, you can uncover significant savings on energy, water, maintenance and chemicals.

Learn more

To find out more about AS Filtration’s solutions for finding savings in your cooling tower with filtration and treatment, visit our cooling water solutions page. There, you’ll find a case study demonstrating 375% improvement in heat transfer efficiency in a project using Aqua-Stream and Pathex cooling tower water filtration solutions.

If you would like to discuss how our filtration and treatment solutions can be applied to your specific situation, please call 423.602.9520 to speak to one of our engineers, or complete the Contact Us form.