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Monthly Archives:April 2017

Spinoff that puts phosphorus in its place

Spinoff that puts phosphorus in its place signs key contract

Members of the NRU team and the Barak Lab at UW–Madison’s King Hall. From left to right are Hannah Stern, Tyler Anderson, Mauricio Avila, Menachem Tabanpour, Phillip Barak, Christy Davidson and Nimi Ehr.

In a bit of high-tech judo, a UW–Madison spinoff has started selling a technology to transform phosphorus at wastewater treatment plants from a major headache into an asset.

A process invented in the lab of Phillip Barak, a professor of soil science, extracts phosphorus from the treatment plant and forms the calcium phosphate mineral brushite, which can be sold as dry fertilizer.

Removing the phosphorus makes pipes in the plant less prone to clogging. And the solid leftovers from sewage treatment are easier to recycle on farm fields because they carry less phosphorus, which is both a critical plant nutrient and a major cause of algal pollution in waterways.

On March 23, Barak’s company, Nutrient Recovery and Upcycling LLC, signed a licensing agreement with CNP, a division of Centrisys, both of Kenosha. Centrisys manufactures centrifuges, which are a key piece of equipment in the phosphorus removal process.

Phosphorus in surface-water runoff plays a major role in fertilizing algae in lakes. After about 15 inches of rainfall in June 2008, algae collected on the surface of Lake Mendota in Madison.

Barak did not expect to turn his attention to phosphorus removal and recycling. “I’ve been at UW–Madison for 26 years, and I was known as a theoretical scientist. I was about as surprised as anybody else when this theoretical work started to enter a realm that, unknown to me, was something the real world was concerned about.”

Barak studied structures called compressed Langmuir monolayers, a layer of close-packed molecules creating an ionically-charged surface. He suspected that struvite, which is an ammonium magnesium phosphate mineral found in many kidney stones, could form on them. “I asked Menachem Tabanpour, who was then a high-school student and an intern in my lab, to run an experiment to prove this, and in five minutes, he succeeded,” Barak says. “None of my other experiments had ever worked so fast or so convincingly on a first run!”

Having invented a fast way to make struvite, Barak still “could not imagine what in the world” it could be used for. Then he learned that struvite plugs pipes in wastewater treatment plants – a problem that, he says, costs treatment plants for mid-size cities like Madison about $250,000 annually. But he reasoned that his struvite process would extract phosphorus too late in the treatment plant to mitigate the clogging.

Brushite, a calcium phosphate compound, is the product of a new phosphorus-reduction technology invented by Phillip Barak, a professor of soil science at the UW–Madison.

Then Barak found a way to make brushite, a different phosphorus mineral, early in the treatment process which thus could reduce struvite plugging. “From an operator’s standpoint, that’s a big advantage,” he says, “and this put me in a big hurry to figure out how that would look with brushite.”

Research at NRU and Barak’s UW–Madison lab has been supported by the U.S. Department of Agriculture (Hatch Act and Small Business Innovation Research), the Madison Metropolitan Sewerage District, the State of Wisconsin Center for Technology Commercialization, and the founders of the company.

When the Wisconsin Alumni Research Foundation declined to patent the brushite invention, “it meant I owned the patent and commercialization rights to brushite formation, but that required a gut check. How certain was I myself that this was likely to be a real thing?”

In 2011, Barak and two of his former students, Tabanpour and soil scientist Mauricio Avila, formed Nutrient Recovery and Upcycling (NRU) to develop and sell the patented phosphorus technology. Avila is technical director, and Tabanpour is president. “It was a little nerve-racking at first,” says Barak, “but for a professor there is nothing better than being surrounded by former students.”

To date, NRU has installed one pilot system, with two more on the boards for 2017. The company is also developing a process to recycle nitrogen from wastewater plants.

– The sales pitch to the target market, wastewater plants, stresses multiple benefits from removing phosphorus:

– Operating savings from preventing struvite precipitation in pipes;

– Better ability to meet tightened regulations on phosphorus content in liquid effluent; and

Income from selling brushite, which is “almost identical, pound for pound, to conventional phosphorus fertilizer,” Barak says.

A final advantage concerns the solid leftover from sewage treatment. These biosolids are typically trucked to farm fields to improve water retention and supply nitrogen and phosphorus fertilizer to crops. With phosphorus, however, “Less is more,” Barak says. “It’s crazy. The biosolid will contain less phosphorus,” which gives farmers a better balance between nitrogen and phosphorus.
“So by reducing phosphorus, sewerage districts will be able to load more biosolids per acre, which can save trucking costs and improve use of biosolids as a nitrogen source,” Barak says.

The first pilot plant, Woodridge, Illinois, performed well, Barak says. “We were making tons of this brushite fertilizer — this is not a wimpy sort of thing.” Visitors from a tradeshow at the Water Environment Federation [the professional organization of wastewater plant operators] saw “brushite raining out of the digester. It was like snow in a snow globe, right there in front of the eyes of a busload of experts.”

As NRU moves toward its first sales, “Being able to criticize your own work is an essential part of being a scientist,” Barak says, “and I keep looking for blemishes in the silver lining, but I am not finding any.”

© 2017 Board of Regents of the University of Wisconsin System

Vortisand® Cooling Tower Filtration

High Efficiency Media Filtration and Ultraviolet (UV) Disinfection is becoming a crucial component for today’s cooling tower needs
Taking the heat out of cooling: Data Center Example

An increasing number of technology industries are turning to cooling towers to remove excess heat from buildings or processes. Server farms or server clusters are typically located between the system switches and routers, the removal of heat from these facilities is critical to their optimal performance. The advances in cluster computing, scientific simulation (such as Computational Fluid Dynamics), the rendering of detailed 3D images for health care, and the complex transactions required by web enterprises are all processed at server farms. The buildings cooling capabilities, rather than its processing speed, limit performance of the servers. In many cases for every 100 watts used to power the server, 50 watts is required to cool it. The critical design parameter for these large and complex continuous systems is performance per watt. As a result, maintaining effective and continuous cooling is critical to server performance.

Facebook has established a server cluster in Lulea, Northern Sweden (within 62 miles of the Arctic Circle), to benefit from the availability of cold air. High-speed fiber optic cables link the USA to cooler climates, such as Iceland. Google operates 12 data centers globally, with 6 in the USA, and uses 260 million watts of power, or 0.01% of global power consumption. Amazon operates 450,000 servers across 9 locations globally, with a 10th under construction in Ningxia, China. These complex, large scale operations require a great deal of cooling, and for some time now the trend has been to move away from the use of chemicals and towards non-chemical, more water efficient and critically robust disinfection processes. UV disinfection of the cooling water plays a central role in these process critical applications; preventing harmful microbial growth that can pose a danger to employees, while effecting the performance of the cooling system.

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How does cooling take place
Evaporative Cooling

Evaporative cooling occurs when water evaporates, changing state from liquid to vapor and requires an input of heat energy – the latent heat of evaporation. The input of heat is drawn as a waste product directly from the server facility. Modern heat rejection requirements employ cooling towers or evaporative condensers as the most efficient and cost effective method, maximizing the contact between air and the water to be cooled.

Legionella Bacteria

Cooling towers used in evaporative cooling water systems and domestic hot and cold water systems are a common source of Legionella. The disease is transmitted via the inhalation of mist droplets containing the bacteria. The use of UV water treatment ensures that microbial contaminants are effectively inactivated, including slime formers that impair cooling tower performance. Unlike chemical disinfection systems, organisms do not demonstrate a tolerance or resistance to UV light. Typically, cooling towers require nearly 66% less power to reject a given amount of heat than alternative “dry methods”. In addition, they occupy a smaller footprint and are significantly quieter. Some server farms use reclaimed water for cooling, although all need optimal performance from their cooling loops.

Dissolved Solids

Cooling towers evaporate pure water, leaving any suspended or dissolved solids, such as minerals etc., behind in the retained water. This resultant build-up of solids or concentration factor would leave the water unusable, reducing operating efficiencies and potentially damaging the recirculating system. In an effort to reduce build up, it is necessary to blowdown or bleed a proportion of the system water. In the US, the total dissolved solids (TDS) of the supply water requires that the concentration factor within an evaporative cooling system is maintained at 3 to 3.5 times, requiring an amount of water equivalent to up to 50% of the evaporation losses being bled to waste. For a typical MW (1,000Kw) of heat rejected, this equates to 150 to 200 gallons per hour that is drained to waste. Several novel approaches are being utilized for cooling water systems, including the use of reclaimed or wastewater for cooling in an attempt to reduce the use of potable water. The selection of filtration products that minimize backwash water loss is critical; as a result high efficiency media filters such as the Vortisand® Systems with Cross-Flow Microsand Filtration are specified for the most demanding applications.

Airborne Contaminants

Cooling towers are effective air scrubbers. As a consequence of the cooling method, they flush airborne contaminants into the system where they deposit on and foul the heat exchange surfaces. Suspended matter in the cooling water also supplies waterborne microorganisms with a supply of nutrients. Modern UV systems use automatic wipers to keep the optical path free from contamination. Many of these airborne contaminants, as well as iron in solution in the water, will foul the quartz sleeves and prevent optimal disinfection of the cooling water.

Particulates under 5 micron in size contribute to reduced cooling efficiencies by fouling the surfaces of heat exchangers.

Microbial and fouling concerns in cooling systems

Fouling, Biofilm & Slime

The dynamics of flora and fauna in cooling water systems are beginning to be better understood. In systems where a single microbial group or species dominates, fouling problems can often occur. In a balanced population mix, often little or no fouling is evident. It is probable that when mixed populations co-exist, they compete for the available oxygen and nutrients, and so control each other’s growth. When one group successfully displaces the others, its growth can proceed without competition, leading to the quick formation of biofilm and slime.

Colonizing Bacteria

A wide variety of bacteria, including Klebsiella Pneumoniae and Bacillus Emegaterium, can colonize cooling systems. Spherical, rod-shaped, spiral, and filamentous forms are common. Some are spore producing to survive adverse environmental conditions, such as dry periods or high temperatures. Both aerobic bacteria (needing oxygen to survive) and anaerobic bacteria (such as Desulfovibrio Desulfurcans – SRB that can survive in the absence of oxygen) are found in cooling systems. The SRB species are directly linked to Microbial Induced Corrosion (MIC), as they metabolize Sulfur and form Hydrogen Sulfide as a waste product. This then leads to hydrochloric acid formation, causing corrosion of pipes and structures.

Fungi

Several forms of fungi are encountered in cooling systems, including Candida Krusei and Trichoderma Viride. Filamentous molds will lead to rot of any exposed wood and as with yeasts; they are prolific slime formers that will impair cooling performance.

Algae

Algae, including Chlorella Pyrenoidosa and Scenedesmus Obliquus, are commonly found in cooling systems. Green and blue-green algae are very common in cooling systems. Several species of algae will produce the growths that foul screens and block distribution decks. Without disinfection, algae fouling will lead to unbalanced water flow and dramatically reduced cooling tower efficiency.

Combination of high media filtration and ultraviolet (UV) systems
​Ultraviolet (UV) Systems

A high efficiency media filtration system and UV combination can remove contaminants before they have a chance of increasing the cost of operation, cause infection, and/or cause a shutdown situation. Earlier applications of UV, for cooling water loops, was to disinfect a side-stream flow. Modern, high capacity UV systems, when used with the correct separation processes, can deliver a high dose of UV to the cooling loop and turn over the entire reservoir frequently. A key benefit of UV disinfection is that the water cannot be overdosed.

High Efficiency Media Filtration Systems

Typically a cooling system will turn over the entire volume of water several times each hour. A typical reservoir might contain 7,000-15,000 gallons, with a filtration rate of 500 to 1,000 gallons per minute. A 100-ton cooling tower would recirculate the cooling water at 300-500 gallons per minute. Side-stream technologies are a lower cost, but a less effective method to disinfect the cooling system. Process critical applications such as server farms need to have full flow automated disinfection, operating 24 hours a day, 365 days a year.

Vortisand® filtration systems with high efficiency cross-flow technology is a replacement to the older, more traditional sand filters. The Vortisand system is a high capacity media filter that combines cross-flow dynamics with microsand media to achieve submicron filtration performance. This technology allows the unit to operate at filtration rates of up to 5 times greater than those of traditional media filters, while filtering 10-50 times finer. Water from cooling towers attracts and absorbs airborne contaminants on a continuous basis. Typically, 85% of suspended solids in chilled water and hot water loops are smaller than 5 microns. Studies have shown these small particles (5 microns and less) are the adherent contaminants fouling cooling tower and heat exchangers, reducing the performance of the cooling system. Bacteria, such as Legionella, also contribute to this phenomenon.

The Vortisand system typically requires 3-5% of the cooling tower flow, or a turnover rate of 7-12 depending on the tower location. Standard sand filters and centrifugal separators will require typically 10-30% of the cooling tower flow. Due to its particulate removal capabilities, the Vortisand system is an excellent pre-treatment filter for UV applications.

High efficiency media filtration system and UV combination can remove contaminants before they have a chance of increasing the cost of operation.

Summary

​Modern high efficiency media filtration and UV disinfection systems are capable of filtering the full flow of modern cooling loops, and disinfecting the entire water system many times each hour. Server farms are just one of many applications in which high efficiency filtration is critical to attaining optimal ROIs. Having an efficiently operating and clean cooling tower can lead to multiple benefits. Such benefits include a cleaner HVAC system, reduced maintenance costs and higher operating efficiencies. Industrial applications can also benefit; having a clean source of cooling tower water to pull from will help meet improved levels of production and quality.

Contact our team of water experts to learn how the Vortisand® and ETS-UV™ systems can help you meet your water objectives!

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References

1. U.S. Department of Energy (2011). Cooling Towers: Understanding Key Components of Cooling Towers and How to Improve Water Efficiency. DOES/PNNL-SA75820
2. Amir Samimi (2013). Micro-Organisms of Cooling Tower Problems and How to Manage Them. International Journal of Basic and Applied Science, 01 (04), 705-715.
3. http://www.zdnet.com/pictures/facebooks-data-centers-worldwide-by-the-numbers-and-in-pictures/
4. https://www.google.com/about/datacenters/inside/locations/index.html

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