As stay-at-home orders are eased and people are returning to work in-person, a careful look at building water systems should be part of the reopening plan (See this article from WaterOnline.com). Water sitting in pipes and rising spring temperatures can be perfect conditions for bacterial growth, including Legionella.

Pathex antimicrobial filter media has been proven to kill and control bacteria in building water systems.

Contact AS Filtration and use Pathex as part of your water management plan.

While COVID-19 has temporarily closed many buildings, the operations of their water systems have also been drastically reduced. This can result in optimal conditions for the growth and spread of Legionella. As businesses begin to reoper, the CDC has released guidance for building water systems, with the first step being to establish or update a water management program. The guidelines can be found here: www.cdc.gov/coronavirus/2019-ncov/php/building-water-system.html.

Water filtration using Pathex has been proven to kill and control waterborne bacteria, while improving operating efficiency and equipment life. Contact us today to learn about using Pathex to update your facility and protect against waterborne bacteria, including Legionella.

In the summer of 2018, AS Filtration installed a large 3-vessel filtration unit to treat the cooling water for eight cooling towers. The cooling system is used for climate control of 1-million sq-ft. of office spaces and critical systems, including an on-site data center.

When filtration with with Pathex began, bacteria levels were high. Bacteria counts were approaching 19,000 spc/mL, despite a professional chemical treatment plan. Using Pathex, waterborne bacteria levels were reduced by 90% within 2 weeks, and more than 99% in the next 8 weeks. Similarly, TSS was reduced to undetectable levels within 6 weeks of implementing Pathex.

More than 18 months after installation, Pathex is maintaining extremely low bacteria and TSS levels and maximizing the operating efficiency of the cooling system. One employee said that the water in the cooling tower basins was so clear, he thought they were empty!

For more information on this, or to find out how Pathex can help with your water treatment needs, Contact AS Filtration!

The Pacific Northwest National Laboratory, in the paper "Side Stream Filtration for Cooling Towers" (PNNL, 2012), estimates that substantial energy and water savings can be achieved through the use of a side stream filter on a cooling system. This study predicts a minimum energy savings of 10% and a decrease of blowdown frequency that allows water to be used up to 33% longer before discharge is needed. Side stream filtration with Pathex antimicrobial filter media enhances these benefits by killing and controlling waterborne coliform bacteria in the cooling system. Contact AS Filtration to learn more!

Thermal conductivity is significantly affected by fouling, a thin insulating layer or film that accumulates on heat transfer surfaces. In fact, a fouling layer of just one thousandth of an inch (0.001") increases system power requirements by 10%. Fouling can be caused by biofilm or suspended solid particles that settle on heat exchangers. Side stream filtration with Pathex antimicrobial filter media addresses the suspended solids that contribute to fouling, as well as the bacteria that support biofilm formation. Contact AS Filtration to discuss implementing Pathex and improving heat exchanger performance at your facility.

Outbreaks of the potentially deadly Legionnaires' disease have become an increasingly common occurrence in recent years. According to USA Today, reports of Legionnaires' disease cases have increased by more than five times since 2000. A significant number of these cases are found to have originated in cooling towers with high levels of Legionella bacteria. Testing has shown that filtration through Pathex antimicrobial filter media can reduce levels of Legionella by more than 98%.

Contact AS Filtration and learn how to combat waterborne bacteria using Pathex at your facility!

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.

Conclusions:
The Aqua-Stream™ side stream filter, using Pathex® antimicrobial filter media, proved successful during the year-long study in Chattanooga. The goal of a side stream filter on a cooling tower is to treat the water in such a way that operation is more efficient, both financially and in terms of cooling effectiveness. Bacterial presence in the Chattanooga cooling system was consistently lowered throughout the year to levels significantly below industry standards, commonly exceeding the performance demanded by the cooling industry. As the presence of bacteria encourages the proliferation of other concerns like scaling, fouling, and microbiologically influenced corrosion, its removal results in improved operational efficiency (PNNL 2012). Additionally, the removal of chlorine chemical treatment for the year suspended the corrosive action of oxidizing biocide treatments. The negative environmental impacts of chemical use were also halted. Finally, the financial savings from the use of a side stream filter were estimated to be $10,646 per year, including a savings of approximately 228,000 gallons of water, using the Pacific Northwest National Laboratory formula for a comparable, properly maintained 400-ton cooling tower.

The use of the Aqua-Stream™ side stream filter and Pathex® antimicrobial filter media from AS Filtration™ successfully controlled waterborne bacteria and provided exceedingly beneficial results for the year-long study in Chattanooga. The side stream filtration system would reasonably be expected to continue to improve the condition and operation of the cooling tower system, with minimal maintenance requirements. Several side stream filters utilizing Pathex® have been in continual operation for nearly a decade, with proper maintenance and backwashing, and continue to operate as designed for the control of bacteria in cooling systems. Given the proven benefits of the Aqua-Stream™ side stream filter with Pathex® antimicrobial filter media, its continued use on the Chattanooga cooling tower system would result in ongoing financial savings and improved operational efficiency for many years to come.

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.

Economics:
Side stream filtration offers savings in energy and water consumption, as well as maintenance and equipment costs. The formula used by the Pacific Northwest National Laboratory in the paper “Side Stream Filtration for Cooling Towers” is applied below to simulate the annual energy cost for a 400-ton cooling tower, similar to the one at the Chattanooga site:

A/C tonnage x kW/ton x load factor x hours of operation/year x cost/kWh = energy costs per year

The cooling tower at the Chattanooga site is a 400-ton tower, this example assigns a 50% operating efficiency, a typical 70% load, 3,500 operating hours per year (roughly 40% of the year), and an energy cost of $0.11 per kWh (the actual cost per kWh at the location during the study, according to supplied records). Using these values, the approximate annual operating cost of $53,900 for this cooling tower is calculated as follows:

400 ton x 0.5 kW/ton x 0.7 load factor x 3,500 hours/year x $0.11/kWh = $53,900/year

The Pacific Northwest National Laboratory anticipated the side stream filter to result in a minimum energy savings of 10%, or $5,390 per year. Also, the frequency of required blowdown was expected to decrease, allowing water to be utilized by the cooling tower roughly 33% longer, saving 228,000 gallons per year. Using a combined water cost of $7 per thousand gallons, the actual average cost at the location, this decrease in water demand would result in water cost savings of $1,596 annually. It was also expected to cut required maintenance in half, leading to a conservative estimate of $2,160 of savings per year. All chemical treatment was removed for the study, relying only on the Aqua-Stream™ and Pathex® for water treatment, saving approximately $1,500 per year in chemicals. In total, the installation of this side stream filtration system on a properly maintained cooling tower would result in an estimated savings of $10,646 annually (PNNL 2012).

Contact AS Filtration to find out more about using the Aqua-Stream™ and Pathex® at your facility!

Maintenance and Equipment:
Cooling towers are inherently dirty systems due to their operation and being open to the environment. As explained in a previous entry, cooling towers harbor a constantly increasing amount of contaminants and impurities. Traditionally, this build up would require the cooling tower to be shut down, drained, and the layers of sediment and other deposits to be manually removed. It is not uncommon for a properly maintained cooling tower to undergo this cleaning twice a year, costing extra in downtime, labor, lost water from draining and refilling the system, and additional cleaning chemicals (PNNL 2012). Side stream filtration, by constantly “cleaning” the water within the cooling tower, provides for considerably longer periods of operation between shutdowns for required maintenance actions, drastically reducing the annual cooling tower maintenance costs. In a study at the Oak Ridge National Laboratory, annual maintenance requirements for a 400-ton cooling tower with a side stream filter were 80% less than a comparable tower not using side stream filtration. In this example, the cooling tower with a side stream filter took half a day to be cleaned out by a vacuum truck, while the non-filtered tower took two and a half days to clean (US DOE FEMP 2014).  In addition, keeping the system cleaner extends the life of the equipment, meaning cooling towers and their components can be used longer before needing replacement or maintenance.

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-StreamTM and Pathex® on bacteria, energy use, water use, and overall equipment/maintenance costs.

Neglecting to perform preventative maintenance can degrade cooling tower performance and increase the water and energy required to cool effectively. It can also shorten the life of cooling system equipment. Side stream filtration can help reduce required maintenance and lengthen the amount of time in between maintenance actions. Pathex® further enhances the effects of side stream filtration by killing waterborne bacteria and improving overall water quality within the cooling system.

Contact us today for more information and to learn how to use Pathex® at your facility!

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 (Image 1). 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.

Water:
Water is a fundamental component of any cooling tower system, as it is the medium through which heat exchange is achieved.  Cooling tower operation, with side stream filter placement options, is depicted in Figure 1, below. The Aqua-Stream™ filter at the Chattanooga site is located between the pump and heat exchanger (Option 2, below).  As water passes through the heat exchanger, waste process heat is transferred to the cooler water, allowing equipment to operate without overheating. A portion of this hot water is then evaporated in the cooling tower, with the remaining water being cooled for reuse through the heat exchanger.
Cooling towers consume water in two ways: evaporation and blowdown. Evaporation, as seen above, occurs as part of normal cooling tower operation. Because of this, the remaining water retains a constantly growing concentration of dissolved solids. Blowdown manages this issue by purging the water with high concentrations of solids or minerals, often to the sewer system, and refilling the system with clean (usually municipal) water. The longer water can recirculate through the system before blowdown is required, the less water the cooling tower consumes. Side stream filtration helps manage water usage by constantly filtering and removing the suspended and dissolved particles that lead to blowdown. Logically, this translates into water savings, as less make up water is required to operate the cooling tower.

The next entry will examine the maintenance requirements and equipment costs associated with cooling systems and their operation.