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.

ENERGY STAR labels are familiar sights on appliances, light bulbs and other products, and now, over 26,000 buildings also boast the certification. ENERGY STAR certified facilities earn the designation by demonstrating that their energy performance score is better than 75% of buildings nationwide. For green-minded businesses, the certification offers visible confirmation of their leadership in environmental stewardship. 

So what does water filtration have to do with energy efficiency and ENERGY STAR certification? Cooling towers can account for 20% or more of a facility’s energy costs, so they’re prime targets when identifying opportunities for saving energy – especially in warm climates where the towers run continuously for much of the year. And selecting a filtration system that removes suspended solids and controls bacteria can significantly improve the operational efficiency of cooling systems, resulting in energy savings of up to 40%!

AS Filtration’s cooling water solutions include the high-efficiency Aqua-Stream side-stream filter and Pathex antibacterial filter media. Together, they continuously filter a portion of cooling water to remove suspended solids (down to 0.5 microns) and kill waterborne bacteria on contact. The result is a highly efficient system with clean water and clear tubes and pipes. Killing bacteria concurrently with filtration leaves behind cooling water that’s clear, clean and no longer prone to the scaling, corrosion, and biofilm that make cooling towers sluggish energy hogs. View a case study highlight to see how one hotel saved 162,490 kWh per year with Pathex filter media in side-stream filters.

If your business is interested in earning ENERGY STAR certification, don’t forget to include your cooling water treatment system in your hunt for energy savings.

AS Filtration takes on a limited number of pilot programs each year to demonstrate the effectiveness of our cooling water solutions. If your business is working toward ENERGY STAR certification and would like to become a test site, please contact us.