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.

Begin updating your water management program today 

In our previous entries, we touched on the basics of the ASHRAE Standard 188-2015, why it’s important, and what buildings and facilities are impacted. Now, we’ll take a look at what you should do to follow the published guideline. 

Establishing a water treatment program
Most cases of Legionellosis are the result of exposure to Legionella bacteria associated with building water systems, so the standard requires use of a water management program to reduce the risk of Legionellosis associated with those systems. 

The water treatment framework within the standard includes these components: 

• Program team identification
  Indicate who is responsible for implementing and monitoring the water management program. 
  

• Description and analysis of building water systems
  Indicate the location and flow of water systems, then identify those that pose the most significant risk for Legionellosis and note where water treatment can be applied. 
  

• Control measures
  This is the heart of the standard. Choose and install water treatment measures to effectively reduce the risk of Legionella. Document all treatment measures taken, their implementation schedules and processes, measurement parameters, and corrective actions for each control measure. 

 

• Verification and validation
  Outline specific, scheduled reviews of water treatment program documentation and processes to ensure the program is being implemented. Then, perform periodic water sampling of building water systems to validate the efficacy of your treatment measures. Routine testing specifically for Legionellosis is the most direct method for confirming the effectiveness of your program. 
  

What should I do with the written plan and program compliance information?
Simply keep the documentation and make it available for review as needed by the party or parties responsible for enforcing the requirements of ASHRAE Standard 188-2015. 

AS Filtration’s Legionella Risk Management Solutions
Your water management program must include disinfectant to kill or inactivate pathogens, as well as water treatment products to control microbiological activity, scale, and corrosion.  

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).  

Pathex® antimicrobial filter media removes particles and controls waterborne bacteria. It’s included in our Aqua-Stream filtration system and is also a drop-in replacement for most sand and multi-media filters. Unlike plain sand filters that often harbor bacteria, Pathex kills waterborne bacteria on contact. Pathex is EPA registered as a pesticide under FIFRA sec 3(c)(7)(A) and is certified by NSF International to NSF/ANSI Standard 61 for drinking water system components.  

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

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

New standard sets guidelines for reduction and control of Legionella bacteria 

The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has published ASHRAE Standard 188-2015, an industry guideline for Legionellosis risk management, to protect public health by controlling Legionella bacteria in building water systems. 

Low levels of Legionella bacteria are present in nearly all bodies of water and can cause Legionellosis (Legionnaire’s Disease), a serious and sometimes fatal form of pneumonia. The illness is spread through fine water particles, like mist dispersed by hot tubs and fountains. The disease is not spread person-to-person. According to the Centers for Disease Control and Prevention (CDC), 8,000 to 18,000 people in the United States are hospitalized each year from the disease. Most recently, a deadly outbreak occurred in New York, and a factory was shut down briefly in North Carolina after Legionella bacteria were found in its cooling towers. 

What is ASHRAE Standard 188-2015?
The standard is an industry guideline establishing minimum Legionellosis risk management requirements for building water systems such as cooling towers, evaporators, fountains, and hot tubs. It provides an outline for Legionella control measures and gives building owners leeway in choosing a compliant water treatment program.

The standard requires that affected facility owners/managers implement and document an effective, written water treatment program with Legionella control measures that comply with the stated guidelines. 

Does the standard include a list of required treatment methods?
No, the standard offers only a framework for Legionella risk management and leaves specific water treatment measures to the discretion of your water program team. This flexibility is intentional and recognizes that there is great variation among individual buildings and water systems, and that no single solution is ideal for every application. Regardless of your chosen treatment method, ongoing control measures and active testing are part of any effective program. 

Are there penalties for non-compliance with the standard?
According to OSHA, organizations are legally required to protect occupants from known dangers, and Legionella may be considered a known hazard. Although the Standard 188-2015 is not a law, organizations may be found negligent in court if testing demonstrates a failure to comply with the published guidelines.   

Earlier this month, New York City Council adopted legislation requiring adherence to part of the Legionella standard, and other cities, counties and state agencies may follow suit. 

In our next blog, learn more about the buildings and facilities impacted by the standard. Then, read the final entry to find out how to comply with the standard. You’re also invited to visit our Legionella Risk Management Solutions page for information on water treatment products that may enable ASHRAE 188 compliance in your facility.