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.

Now that cooler weather is upon us, it’s time to perform HVAC system maintenance and lay up cooling towers for winter. If your system struggles to keep up with the summer’s heat and humidity, now is the perfect time to evaluate your cooling water treatment program and consider making a switch.
 
Take, for example, a hotel in Washington, D.C. that traded biocide chemicals for Pathex filter media and hasn’t looked back:

The Problem
Biofilm, scaling and corrosion were winning the battle in the cooling tower of a Washington, D.C.’s 10-story hotel. Resulting operational inefficiencies in the 200-ton cooling tower led to guests complaining about hot, muggy rooms.

The Solution
An Aqua-Stream high-efficiency side-stream filter, fitted with Pathex antibacterial filter media, was installed. The Aqua-Stream efficiently filters suspended solids, and Pathex replaced the oxidizing chemical biocides that weren’t adequately killing bacteria in the cooling water.
 
Together, the products improved heat transfer efficiency, reduced water and energy consumption and decreased maintenance needs for the hotel – ultimately resulting in cooler, more comfortable rooms for hotel guests.
 
The Outcomes
Cleaner air, cooler water and significant savings.
 
Read the case study for additional outcomes or contact us to discuss your cooling tower filtration needs.

Already have a side-stream filter? Consider switching to Pathex filter media to boost the power of your filter. It’s a drop-in replacement for most sand and multi-media filter beds. Pathex kills bacteria on contact without using or leaching chemicals.

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.

Having a dirty water filter in your cooling tower is almost as bad as having no filter at all. Over time, media beds can clog with biological growth and debris, like dust, dirt and pollen, that diminish the filter’s ability to remove suspended solids. This buildup makes your whole system work harder and leads to problems like these:

• Channeling in the media bed
• Caking (hardening) of the media bed
• Increased turbidity
• Reduced capacity
• Harboring waterborne bacteria
• Decreased heat transfer

 
A dirty water filter is not only inefficient; it can also be dangerous if it becomes a breeding ground for harmful bacteria like Legionella.
 
Chemicals are the typical solution for keeping filters clean. However, they can be costly and hazardous to handle and store, they frequently create harmful byproducts, and they require constant tinkering to get the balance just right as environmental and process factors fluctuate.
 
A safer alternative is now available. AS Filtration’s groundbreaking filter media destroys bacteria on contact and requires only a simple backwash to remove debris and allow the filter to operate effectively at optimal flow rates. The antibacterial property of the filter media prevents the formation of biofilm and inhibits the growth of new bacteria in the system, putting an end to caking and channeling of the media bed.
 
The proactive nature of the filter media also prolongs the lifespan of pipes, tubes, valves and downstream equipment by addressing scaling and corrosion caused by biological growth and harsh chemical treatments.  Plus, your facilities staff will thank you for sparing them the chore of chipping out solidified media beds!
 
See how else this new technology stacks up against other water disinfection solutions for keeping your cooling tower filters clean:

You may also be interested in our blog: How Low Can You Go? Is Your Cooling Tower Water Filter Missing 85% of Suspended Solids?

An overview of the facility types impacted by ASHRAE Standard 188-2015 

In our last blog, we talked about ASHRAE Standard 188-2015 and why it was developed to reduce and control Legionella bacteria in building water systems, including fountains, whirlpools and cooling towers.  

Now, we’ll describe the types of buildings and facilities identified in the standard as being at-risk for Legionella bacteria. If your facility falls into one of these categories, you should familiarize yourself with the standard and begin implementing a compliant water treatment program.  

Who needs to read the standard?
The ASHRAE Standard 188-2015 is intended for use by owners and managers of “human occupied commercial, institutional, multiunit residential and industrial buildings.”  

The standard requires a written water treatment program for facilities with the following risk factors:

• Open and closed circuit cooling towers or evaporative condensers 
  
• Whirlpools or spas (hot tubs), on the site or in the building
  
• Ornamental fountains, misters, atomizers, air washes, or humidifiers 
  
• Non-potable water systems or devices that release water droplets in the building or on the site
  

 
In addition, the standard requires written water treatment programs for*: 

• Multiple housing units with one or more centralized potable water-heater systems
  
• Buildings more than 10 stories high (including any levels that are below grade)
  
• Health care facilities where patient stays exceed 24 hours
  
• Buildings containing one or more areas for the purpose of housing or treating occupants receiving treatment for burns, chemotherapy for cancer, or solid organ transplantation or bone marrow transplantation
  
• Buildings identified as being for the purpose of housing occupants over the age of 65 years
  
• Buildings that house or treat occupants who are at higher risk from becoming ill through exposure 

Owners/managers of new and existing buildings should complete an assessment of the premises identifying any risk factors listed prior to occupancy of a new building or before construction begins on renovations, additions, or modifications to existing buildings.   

The ASHRAE standard also applies to those involved in the design, construction, installation, commissioning, operation, maintenance and service of a centralized building water system and components to ensure compliance. 

Single-family residences are not included in the standard. 

In our next blog, we’ll talk more about how to comply with the standard to reduce the risk of a Legionnaire’s Disease outbreak at your facility. You’re also invited to visit our Legionella Risk Management Solutions page for information on water treatment products that may enable compliance in your facility.

*please read the full standard for more specific details about at-risk facilities

The cause of Legionnaire’s Disease, Legionella bacteria, is present at low levels in many bodies of water. But it thrives in warm, damp environments like cooling towers and whirlpool spas and can pose a serious health risk when dispersed in mist or fine droplets.
 
Fortunately, reducing and controlling Legionella is relatively easy to do with an effective, continuous water treatment program that is regularly evaluated and maintained. The recently published ASHRAE Standard 188-2015 for managing Legionella risk outlines water treatment program guidelines for monitoring and reducing the bacteria in building water systems. It’s an excellent starting point for establishing or updating a water treatment program for your facility. 

A central component of the standard is control measures to inactivate or kill pathogens as well as reduce scaling, corrosion, and biofilm in cooling towers and evaporative condensers. Control measures are also required for potable water systems, whirlpool spas, ornamental fountains, and aerosol generating misters, atomizers, air washers, and humidifiers.  

There’s no single solution that is best for every application, but our filtration products can be valuable components of your water treatment program for managing Legionella risk in many new and retrofit situations.  

Aqua-Stream™ High-Efficiency Side-Stream Filter
The Aqua-Stream filtration system has been proven to kill and control waterborne bacteria while removing suspended particles as small as 0.5 micrometers (microns). It provides continuous filtration and uses a small footprint, so it’s ideal as a water treatment product in retrofit and critical facility applications .
 
Pathex® Filter Media
Pathex antimicrobial filter media is the key to successful particle removal and controlling waterborne bacteria without the use of chemicals. (See our Technical Report, Breakthrough Filter Media Technology Kills Bacteria on Contact). Pathex is included in the Aqua-Stream filtration system and can also be used as a drop-in replacement for most sand and multi-media filters. Unlike plain sand filters that may harbor bacteria, Pathex kills waterborne bacteria on contact. Pathex is EPA registered as a pesticide and is NSF/ANSI Standard 61 certified for drinking water system components.  

For more information about Legionella risk reduction, please visit our Legionella Risk Management Solutions page or contact us for a free consultation.

Traditional water treatment solutions for cooling towers combat scaling, corrosion, fouling and microbiological growth in two steps: filtration and chemical treatment.

Removing suspended solids with side-stream filtration
Rather than treating all cooling water at once, side-stream filters continuously clean a portion of cooling water, so that the entire water volume is filtered over the course of a day. Traditional side-stream filters are designed to remove suspended solids and silt from water, offering benefits that lead to improved operational efficiency.

In the 2012 paper, “Technical Evaluation of Side Stream Filtration for Cooling Towers,” the Federal Energy Management Program (FEMP) discusses the effectiveness of side-stream filters as solutions for combatting the primary water treatment concerns in cooling towers:

1. Corrosion
   
2. Scaling
   
3. Fouling
   
4. Microbiological Activity
   

By continuously removing solids, silt and organics, side-stream filters diminish fouling and biofouling in the system, which, in turn, reduces scaling and corrosion. However, cooling tower water treatment programs that utilize side-stream filters still require additional disinfection to control waterborne bacteria.

Controlling microbiological activity with chemical biocides
The FEMP report states that most mechanical filtration systems focus on the removal of suspended solids greater than 10 microns in size. But roughly 90 percent of suspended particles are smaller than that! Those smaller particles are typically bacteria, and traditional water treatment programs require oxidizing or chemical biocides for bacterial disinfection.

Those biocides require constant monitoring and can be harmful to handle and store. Often, they can create hazardous byproducts, and they contribute to corrosion of pipes and tubes in the HVAC system. That corrosion creates suspended particles that perpetuate the need for filtration and leads to increased maintenance and shortened equipment lifespans.

A single solution
The Aqua-Stream™ high efficiency side-stream filter takes a revolutionary approach to cooling tower water treatment by filtering suspended particles and killing waterborne bacteria in a single step. 

The high-efficiency sand filter removes particles down to 0.5 microns in size, but the magic really happens when bacteria comes into contact with the antimicrobial filter media (Pathex®). The EPA-registered filter media kills bacteria on contact, reducing the need for water treatment chemicals by as much as 90 percent. 

The one-two punch of filtration and bacterial control improves operational efficiency by removing suspended particles and preventing the build-up of biofilm. Aqua-Stream can be sized to meet your flow rate needs, and its small footprint makes it ideal for settings where space is at a premium.

Why pay for two solutions, when you only need Aqua-Stream?

Contact us to see whether Aqua-Stream can solve your water treatment problems.

You may also like Side-Stream Filtration Saves Cooling Tower Water, Maintenance.