the Analyst The Voice of the Water Treatment Industry
Volume 25 Number 3
9707 Key West Avenue, Suite 100 • Rockville, MD 20850
Summer 2018
Design and Care of Reverse Osmosis Systems DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers PBTC Revisited
Volume 25 Number 3 Summer 2018
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the Analyst The Voice of the Water Treatment Industry
Volume 25 Number 3
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Summer 2018
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Design and Care of Reverse Osmosis Systems DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers PBTC Revisited
Volume 25 Number 3 Summer 2018
Summer 2018 Volume 25
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Number 3
10 Design and Care of Reverse Osmosis Systems
Wes Byrne, U.S. Water Services, Inc. Reverse osmosis (RO) systems offer power plant owners and operators a reliable and wellproven water treatment solution; however, designing and caring for an RO system requires a thorough understanding of a plant’s water supply and the technology’s capabilities. The information presented in this article could help plant engineers design and optimize an RO system to match their needs.
28 DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers
Linna Wang, Claudia C. Pierce, Dorothy Reynolds, Suez Water; and Elizabeth Summer, Ecolyse, Inc. Effective microbial control in cooling systems is necessary to ensure system cleanliness and to avoid fouling that degrades cooling system performance, promotes corrosion, and favors growth of pathogens. Controlling organisms optimally, however, involves an understanding of the identity of the population of microbes in a system due to the varying susceptibilities of organisms to biocides. This is a challenging task with standard culturing techniques, which only allow for a small fraction of the total population to be cultured and identified. In this study, 16s rDNA was employed to maximize the population identification of 40 different independent cooling tower samples. Many of the samples included pair planktonic and sessile samples from the same location. The analysis yielded over 282,000 sequences, which corresponded to over 1,700 different taxa, demonstrating extensive diversity not only from remote locations but also within locations of close proximity. This shows that a wide variety of biocides are needed to address microbial populations.
48 PBTC Revisited
Robert J. Ferguson, French Creek Software, Inc., and Richard Ashcraft, Athlon Solutions PBTC (2-phosphonobutane 1,2,4-tricarboxylic acid) has become the workhorse for calcium carbonate scale inhibition in cooling water, water reuse, and water treatment applications operating at the edge of control technology. This paper provides findings based on over 30 years of field application and recent laboratory studies to elucidate the behavior and performance of this "go to" inhibitor over a broad range of conditions. Data developed and reported includes inhibitor minimum effective dosage requirement as a function of saturation ratio (scaling index), temperature as it affects rate, residence time, and PBTC dissociation state. Performance as the sole inhibitor, and when applied with commonly used polymers, is also discussed.
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Calendar of Events
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President’s Message
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Message From the President-Elect
59 Membership Benefits 60 Association News 61 Industry Notes 66 Making a Splash 68 Charity Update 70 CWT Spotlight 71 Ask the Experts 72 T.U.T.O.R. 77 Capital Eyes 79 Business Notes 81 Financial Matters 82 Advertising Index
the Analyst Volume 25 Number 3
9707 Key West Avenue, Suite 100 Rockville, MD 20850 (301) 740-1421 • (301) 990-9771 (fax) www.awt.org
2018 AWT Board of Directors President
Marc Vermeulen, CWT
Calendar of Events
Association Events 2018 Annual Convention and Exposition
Secretary
September 26–29, 2018 Omni Orlando Resort at ChampionsGate Orlando, Florida
Treasurer
2019 Annual Convention and Exposition
President-Elect
David Wagenfuhr, LEED OPM
Thomas Branvold, CWT
September 11–14, 2019 Palm Springs Convention Center and Renaissance Hotel Palm Springs, California
Michael Bourgeois, CWT
Immediate Past President
Bruce T. Ketrick Jr., CWT
Directors
Matt Jensen, CWT Andy Kruck, CWT Bonnee Randall Andrew Weas, CWT
2020 Annual Convention and Exposition
Ex-Officio Supplier Representative
Kevin Cope
Past Presidents
Jack Altschuler John Baum, CWT R. Trace Blackmore, CWT, LEED AP D.C. “Chuck” Brandvold, CWT Brent W. Chettle, CWT Dennis Clayton Bernadette Combs, CWT, LEED AP Matt Copthorne, CWT James R. Datesh John E. Davies, CWT Jay Farmerie, CWT Gary Glenna Charles D. Hamrick Jr., CWT Joseph M. Hannigan Jr., CWT Mark R. Juhl
Brian Jutzi, CWT Bruce T. Ketrick Sr., CWT Ron Knestaut Robert D. Lee, CWT Mark T. Lewis, CWT Steven MacCarthy, CWT Anthony J. McNamara, CWT James Mulloy Alfred Nickels Scott W. Olson, CWT William E. Pearson II, CWT William C. Smith Casey Walton, B.Ch.E, CWT Larry A. Webb
Staff
Executive Director
Heidi J. Zimmerman, CAE
Deputy Executive Director
Sara L. Wood, MBA, CAE
Senior Member Services Manager
Angela Pike
September 30–October 3, 2020 Louisville Convention Center and Omni Hotel Louisville, Kentucky
2021 Annual Convention and Exposition
September 22–25, 2021 Providence Convention Center and Omni Hotel Providence, Rhode Island
2022 Annual Convention and Exposition September 21–24, 2022 Vancouver Convention Centre Vancouver, Canada
2023 Annual Convention and Exposition
October 4–7, 2023 Grand Rapids Convention Center and Amway Grand Hotel Grand Rapids, Michigan
Also, please note that the following AWT committees meet on a monthly basis. All times shown are Eastern Time. To become active in one of these committees, please contact us at (301) 740-1421.
Vice President, Meetings
Second Tuesday of each month, 11:00 am – Legislative/Regulatory Committee
Meetins Manager
Second Tuesday of each month, 2:30 pm – Convention Committee
Meetings Manager
Second Wednesday of each month, 11:00 am – Business Resources Committee
Grace L. Jan, CMP, CAE Morgan Prior
Kristen Jones, CMP
Exhibits and Sponsorship Manager
Second Friday of each month, 9:00 am – Pretreatment Subcommittee
Barbara Bienkowski, CMP
Second Friday of each month, 10:00 am – Special Projects Subcommittee
Brandon Lawrence
Second Friday of each month, 11:00 am – Cooling Subcommittee
Julie Hill
Third Monday of each month, 9:00 am – Certification Committee
Marketing Manager
Jeyin Lee
Third Monday of each month, 3:30 pm – Young Professionals Task Force
Director of Editorial Services
Third Monday of each month, 4:30 pm – Standards Task Force
Accountant
Third Tuesday of each month, 3:00 pm – Education Committee
Exhibits and Sponsorship Coordinator Marketing Director
Lynne Agoston
Dawn Rosenfeld
The Analyst Staff Publisher
Third Friday of each month, 9:00 am – Boiler Subcommittee Third Friday of each month, 10:00 am – Technical Committee
Heidi J. Zimmerman, CAE
Quarterly (call for meeting dates), 11:00 am – Wastewater Subcommittee
Lynne Agoston
Other Industry Events
Managing Editor
Advertising Sales
Heather Prichard, advertising@awt.org
The Analyst is published quarterly as the official publication of the Association of Water Technologies. Copyright 2018 by the Association of Water Technologies. Materials may not be reproduced without written permission. Contents of the articles are the sole opinions of the author and do not necessarily express the policies and opinions of the publisher, editor or AWT. Authors are responsible for ensuring that the articles are properly released for classification and proprietary information. All advertising will be subject to publisher’s approval, and advertisers will agree to indemnify and relieve publisher of loss or claims resulting from advertising contents. Editorial material in the Analyst may be reproduced in whole or part with prior written permission. Request permission by writing to: Editor, the Analyst, 9707 Key West Avenue, Suite 100, Rockville, MD 20850, USA. Annual subscription rate is $100 per year in the U.S. (4 issues). Please add $25 for Canada and Mexico. International subscriptions are $200 in U.S. funds.
WEFTEC, Annual Technical Exhibition and Conference, September 29–October 3, 2018, New Orleans, Louisiana IWC, Annual Conference, November 4–8, 2018, Scottsdale, Arizona RETA, Annual Convention, November 6–8, 2018, Dallas, Texas USGBC, GreenBuild, November 14–16, Chicago, Illinois
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the Analyst Volume 25 Number 3
Bio-Source is a specialty consulting, toll blender, repackager and distributor of EPA registered non-oxidizing and oxidizing biocides. We also distribute a wide range of raw materials commonly used to formulate boiler and cooling water products. All biocides can be resold under the manufacturer’s label or private labeled through a subregistration. All private labels will be printed and maintained current with EPA by Bio-Source.
RAW MATERIALS
BIOCIDES Bromicide Tablets ( BCDMH ) Bromicide Granules Sodium Bromide ( 40 % ) Stabilized Liquid Bromine Trichlor / NaBr Dichlor / NaBr DBNPA ( 20 % ) DBNPA ( 5 % ) DBNPA Tablets ( 40 % ) Glutaraldehyde ( 50, 45, 25, 15 % ) Glut / Quat Blends Isothiazolin ( 1.5 % ) Isothiazolin ( 1.5 % Cu Free ) Isothiazolin / Bronopol Blend Terbutylazine ( 4 % ) TTPC ( 5 % ) TTPC / WSCP ( 5 % ) WSCP ( 60 % ) THPS, Various Concentrations Hydrogen Peroxide / Silver Blends
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President’s Message
By Marc Vermeulen, M.Sc., CWT
8. Basic Water Treatment Calculations 9. Installing Water Treatment Equipment 10. Maintaining Water Treatment Equipment a. Service Visit Overview b. Sample Collection c. Testing d. Inventory and Feed Equipment Checks e. Service Review and Recommendations 11. Inspections 12. Testing 13. Recordkeeping and Reporting 14. Transporting Products
2018 has been a successful year for AWT. It feels like for many months we have been telling you about things that are “coming soon,” and finally, all of the hard work happening behind the scenes is coming to fruition.
AWT App
It took us longer than anticipated, but the water calculations app has been updated to include metric units as well LSI and RSI calculators. If you already have the app on your phone or tablet, you will see a new version the next time you log on. To get the metric version, or if you don’t already have the app, you’ll want to download it at the Apple App Store or on Google Play.
This training is critical to all of us in the industry. Given this, the training will be free to all members. Our goal is to help educate the next generation of water treaters, and we believe this online training will help companies quickly get their employees up to speed.
AWT Online Training
We’re putting the final touches on the “Introduction to Water Treatment” online training. This training is designed to very quickly get a new hire up to speed with our industry and what they can expect to see each day. The content has been divided into an introduction and 14 modules: 1. 2. 3. 4. 5. 6. 7.
Thank You
I am so amazed by the incredible work of AWT’s volunteers. We are so lucky to have such a great community within our association. From the app to the online training to the closed-loop paper—all of these items are created by you, our members. That may seem intimidating. You might read that and think, “how could I possibly contribute?” But you’d be amazed at all the projects we’re working on and what we need help with. It’s not just technical and it’s not all high level. We had a team of people helping with graphics in the online training modules. Volunteers review and vet business information. Our young professionals group works on STEM projects. The success of AWT is deeply dependent upon the amazing participation of you, our members.
Role of a Service Technician Properties of Water a. Why Water Is Used b. Water Quality c. Terms and Definitions Boiler Equipment Pretreatment Equipment Cooling Equipment Basic Water Chemistry Common Water Treatment Components
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the Analyst Volume 25 Number 3
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Message From the President-Elect
By David Wagenfuhr, LEED AP O&M
to any career fairs to promote our industry and recruit new talent, be sure to visit the AWT career center first: https://www.awt.org/membersonly/advocacy/downloadcenter.cfm. There, you will find downloadable and customizable flyers, posters, ads, and social media posts that you can use to promote our industry and your company.
The 2018 Annual Convention and Exposition is right around the corner. We have multiple panel sessions planned, which will allow attendees to hear from more experts and get their questions answered in a more efficient manner.
Outcome 4: Charity
At the conclusion of the board meeting following the convention, I will transition to my role as AWT president. I very much look forward to working with our volunteers to advance our strategic plan.
A lot of AWT members have gone on Pure Water for the World (PWW) trips this year. In fact, some companies are using service trips as an incentive for their staff members—top performers get to go on a service trip paid for by the company. We will have two presentations from PWW during the convention. One will be on this idea of using service trips as an employee benefit, and another will cover the technical aspects of evaluating the silver-embedded ceramic tablet as a secondary pointof-use water purification technology. These are two sessions you won’t want to miss.
Outcome 1: Technical Resources
Marc outlined the new “Introduction to Water Treatment” online training. This is a very exciting development for our industry. The modules will quickly get new and younger employees up to speed. Personally, I can’t wait to add this resource to my company’s current in-house training program. We will be using a laddered approach to professional development, where we supplement our in-house training with AWT’s online and in-person training programs.
AWT has some great programs and services in the works for the coming year, and I look forward to developing them alongside our committed volunteers. I can be reached at dwagenfuhr@h2oeng.com. Thank you for the opportunity, and I look forward to serving you!
Outcome 2: Business Resources
This year, our Business Resources Committee added multiple new services for the membership. At the end of 2017, the committee rolled out a partnership for online leadership and sales training through Dale Carnegie at a greatly discounted rate. It also coordinated discount programs with Deluxe Business Solutions, where many of us purchase checks and other business products. The committee, of course, has also coordinated many highly success business webinars. And finally, it planned and organized the Business Owner’s Meeting at the Annual Convention—an event I am looking forward to attending.
Outcome 3: Advocacy
Colleges and universities will soon be back in session. If you’re planning to go
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the Analyst Volume 25 Number 3
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FILTRATION
Design and Care of Reverse Osmosis Systems Wes Byrne, U.S. Water Services, Inc.
Pure water does not exist in nature; all water in its natural state contains varying amounts of dissolved and suspended matter. Osmosis is the process by which a solvent, such as water, flows through a semipermeable membrane from a less-concentrated solution to one with a higher concentration. This normal osmotic flow can be reversed (reverse osmosis) by applying hydraulic pressure to the more concentrated (contaminated) solution to produce purified water. There is no perfect semipermeable membrane. A small amount of dissolved salt is also able to diffuse through, but this results in low concentrations relative to the feedwater values. The benefits of reverse osmosis (RO) technology should be well understood in water treatment for power generation, particularly because of its potential to reduce operating and maintenance expenses. For most sources of water, RO is the least expensive way to remove the majority of a large concentration of dissolved salts. The term total dissolved solids (TDS) refers to mostly inorganic salts present in solution. The salts exist as cations (mostly calcium, magnesium, sodium, and potassium) and anions (mostly bicarbonate, chloride, sulfate, and nitrate). These positively and negatively charged ions can pass electrical flow, thus determining the conductivity of the water as a measurement of its TDS concentration. Pure water is a poor conductor of electricity. For plants originally built using only ion exchange, adding RO can reduce chemical regeneration requirements by a factor of 20 or more. Complete removal of
regenerable systems might even be considered. With RO upstream removing the bulk of the dissolved salts, the polishing ion exchange systems might be economically replaced with service demineralizer beds that are chemically regenerated by an offsite water service company, or they might be replaced by electrodeionization (EDI). EDI units use electricity to continuously regenerate their ion exchange resins. Some new and existing plants are now required to remove dissolved salts from wastewater streams prior to discharge. A well-performing RO system can make it possible to reuse the water within the plant. The concentrated salt stream remaining after RO treatment can then be more economically hauled to an area better able to handle it environmentally, or it could be evaporated or discarded in some other manner. The political and regulatory advantages of becoming a zero-liquid discharge (ZLD) facility can offset part of the capital and operating costs. But the superior economics of RO operation are only achievable if the system and its upstream treatment components are correctly designed, operated, and maintained.
Analysis of a Water Sample
Pulling a water sample for laboratory analysis is a good start to preparing an RO design (Table 1). A comprehensive analysis provides data on the metals in the water, such as iron, manganese, and aluminum; the dissolved salts (cations and anions); the water pH (acidity); and possibly the inorganic total suspended solids (TSS). A measurement of the total organic carbon (TOC) often correlates with the potential for biological activity.
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Design and Care of Reverse Osmosis Systems continued
Table 1. Water analysis.
This table shows results from an actual water analysis. Results are listed down to the detection limit of the instrument used. Where results fall below these limits, they are reported as less than the detection limit. A dash indicates testing was not requested or was unable to be run. Source: U.S. Water A TSS analysis reveals the concentration of filterable solids in the water. The concentration of dissolved metals (e.g., iron) in the water changes in the sample as they react with oxygen introduced by contact with air. This causes some of the metals to oxidize and become insoluble. The metals that remain suspended may cause the TSS value to increase significantly with many wellwater sources. Biological fouling solids are not well represented in TSS results. The mass of these solids typically becomes negligible when the TSS filter is dried prior to weighing for results. The water could be tested for its silt density index (SDI) if the metals are first separated out of the sample. This test is highly sensitive to the ability of biological solids to coat and reduce the flow rate through its 0.45micron test filter. Its results correlate with the fouling tendencies of a membrane system.
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No analysis is perfect, and water quality can change over time. Even the characteristics of a well-water source can change if the well is relatively shallow. Sampling methods also affect results; some concentrations can change between sample pull and analysis. Metals may attach to the container’s inner surface. Ammonia and carbon dioxide (CO2) may de-gas or CO2 may dissolve from exposure to air. Any of these changes will cause the water pH to change. An accurate water pH is best measured on site. Chemical suppliers can use a water analysis to predict how much purified water (permeate) the RO might safely separate from the source before the dissolved salts become too concentrated in the remaining water and form scale within the membrane elements (Table 2). The water analysis is also used in designing the RO system, both in projecting the purified water quality and in assessing any effect of the salts on system hydraulics. the Analyst Volume 25 Number 3
Design and Care of Reverse Osmosis Systems continued
Table 2. Scale formation potential.
This table shows partial results generated by a scale inhibitor dosage program for a given reverse osmosis (RO) recovery. The scale inhibitor utilized was USW RO-504 at a dosage rate of 8.42 milligrams per liter (K sp = solubility product constant). Source: U.S. Water
Pilot Study for an RO System
Figure 1. Example of a pilot RO system.
An RO system and its pretreatment equipment designed solely on one water analysis may not be fully optimized for the fouling characteristics of the source. It might be oversized or, of greater concern, it might not be ideal for water that has a high membrane-fouling potential. This can best be determined with a pilot study.
Courtesy: U.S. Water
A well-designed pilot study uses components that have been scaled down but still offer the same type of media, and use similar flow velocities and exposure times. The pilot RO (Figure 1) should duplicate the permeate recovery, the permeate flux rate (i.e., the permeate flow per unit of membrane area), and concentrate stream vessel exit velocities, along with the scale inhibitor dosage and shutdown flush methods. When the pretreatment methods are piloted along with the RO, the system operation can be adjusted to minimize the rate of RO membrane fouling, such as by modifying the permeate flux rate, or the rate at which water passes across the membrane surface and through the membrane elements. With the right equipment choices and sizing, it might be possible to eliminate membrane fouling, which could then dramatically reduce operating costs and maximize membrane life.
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Design and Care of Reverse Osmosis Systems continued
The choice of membrane might also be evaluated. With larger systems, demonstrating that a low-fouling membrane element performs better than a standard element helps justify the higher cost. Low-energy elements might be evaluated for their potential to reduce pump sizing and associated power consumption. The pilot study also offers an opportunity to learn more, specifically about what could foul the RO system. A membrane element from the pilot study might be pulled and autopsied, and analysis of the solids makes it possible to choose cleaning solutions best-suited for removing the fouling materials. The effectiveness of the solutions and cleaning methodology could then be verified with the pilot unit. The longer the pilot system is operated, the more information is gained; a minimum of several months is recommended.
Upstream Equipment
The success of a new RO membrane system is often directly related to its pretreatment. Piloting the upstream processes can be challenging in sizing these components for the pilot’s low flow rate. The most important role played by pretreatment is protecting the RO from incompatible substances. With the polyamide thin-film RO membrane commonly used today, the biggest concern is removal or destruction of any chlorine, or other potentially oxidative compounds. This membrane has very little tolerance to free chlorine (present in many municipal water sources), and is only slightly tolerant of chloramines (in other municipal water sources). The most common methods for breaking down chlorine are reducing-agent injection and activated carbon filtration. The most common reducing agent is sodium bisulfite (NaHSO3), which reacts preferentially with free chlorine in breaking it down to the innocuous chloride ion. Sodium bisulfite/sulfite injection systems can fail in ways that degrade RO membrane elements if not quickly remedied. The day tank could run out of solution, or the injection pump could lose power or pump-head prime. The injection pump setting might provide insufficient chemical to handle the full range of chlorine concentrations, or might be set for such a low 14
pulse speed that the chemical does not sufficiently mix with the feedwater. The proper NaHSO3 dosage should be injected any time the RO inlet valve opens, even if this opening is for filling the RO or for flushing it out before a shutdown. There should not be significant pipe length distance between the point of injection and the RO inlet valve, because this length will become fully chlorinated during shutdown by chlorine diffusion. The point of NaHSO3 injection should be immediately upstream of the inlet isolation valve. Activated carbon filtration may offer a more reliable means of breaking down chlorine. During manufacture, non-carbonaceous materials are burned off, leaving porous granules with a high amount of pure carbon surface area. This has a high attraction for adsorbing almost any contaminant, including most organic materials and heavy metals, although there may be limited removal capacity for some contaminants that are shed into the effluent water. The breakdown of chlorine by activated carbon involves an electrochemical reaction, which offers a high capacity for chlorine removal. The carbon gives up electrons to the chlorine atoms, forming innocuous chloride ions (Cl-) that remain in the water. In this reaction, oxygen atoms previously bonded with the chlorine atoms as hypochlorous acid (HOCl) now attach to the carbon surface. Because the carbon also reacts with dissolved oxygen in the water, the carbon surface can become fully oxygenated. It then loses its ability to remove additional chlorine, but this typically takes a few years with inlet chlorine concentrations less than 1 milligram per liter (mg/L). When ammonia is present naturally or when added by a municipality, chlorine chemically bonds with the ammonia to form monochloramine (NH 2Cl) or possibly dichloramine (NHCl 2). The chloramines are not as chemically reactive and require more carbon volume for their breakdown. A catalyzed carbon media is available at an increased cost that improves the carbon reactivity with chloramines and reduces the need for oversizing the carbon filters. Carbon system valves must not leak or otherwise bypass. They should be normally closed and driven by sufficient the Analyst Volume 25 Number 3
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Design and Care of Reverse Osmosis Systems continued
air pressure to prevent chlorinated water from reaching the RO system.
Figure 2. Scale crystals.
Maintenance is critical to the success of either reducing-agent injection or carbon filtration. It is recommended that the activated carbon media be replaced annually, or based on an increase in the effluent concentration of TOC, to prevent the shedding of biological particles into the RO system. Over-injection of sulfite causes increased breakdown of dissolved oxygen in the water. This increases the potential for heavy growth of slime-forming species of bacteria, which can quickly foul an RO system if there is a sufficient concentration of organic food in the water source. This potential can be minimized by maintaining a residual sulfite concentration that is greater than zero but less than 2 mg/L as sodium sulfite, measured using a low-level test with sensitivity of 1 mg/L or less. As long as the sulfite concentration is greater than zero and it is well mixed into the feedwater, free chlorine will not be present.
Preventing Scale Formation
This image shows scale crystals that formed within the feedside spacing material (shown at top) and on the membranes (shown at bottom). Courtesy: U.S. Water
There is typically at least one salt in any natural water source that will concentrate beyond its solubility and potentially form scale. Preventing scale formation (Figure 2) should not be a major challenge unless the water source has an unusually high concentration of a slightly soluble salt, or the RO is being operated with an unusually high permeate recovery.
Acid injection prevents calcium carbonate scale formation but leads to an extremely high concentration of CO2, which is not removed by the RO system and places a high removal demand on downstream ion exchange processes. Also, acid injection alone doesn’t offer much protection against the formation of sulfate or certain other scales.
Scale formation may be prevented by injecting an acid into the inlet water, by softening the water, or by injecting a chemical scale inhibitor. Usually the least expensive method is a scale inhibitor, which slows the rate at which salt crystals grow when their solubility is exceeded.
Softening offers several advantages but suffers from high capital and operating costs unless there are particularly low concentrations of calcium and magnesium hardness in the water. The softener also removes other potential scale-forming ions, such as strontium and barium, and removes metals that would otherwise foul the RO system, such as iron, manganese, and aluminum. But the softening resin also fouls with the metals and then requires periodic chemical treatment. Scale-inhibition chemical suppliers often use software programs to estimate the potential for scale formation. These programs predict the concentrations of salts present in the RO concentrate stream, as well as its pH, to determine how much scale inhibition chemical is needed.
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Design and Care of Reverse Osmosis Systems continued
The potential for silica scale is common with certain groundwater sources in the western United States. Inhibition formulations have shown varied success. Maintaining warmer water temperatures improves silica solubility, as does changing the water pH. Increasing pH is a common strategy, although the water must first be softened to prevent hardness scale from forming when a caustic chemical is injected to raise the pH.
Figure 3. Biologically fouled cartridge filters.
When using a scale inhibitor, it is critical to rinse the RO system of its increased concentration of dissolved salts whenever the RO shuts down. Otherwise, scale particles grow and stick to the membrane surfaces during the shutdown. This rinsing process should be automated and is often performed with low-pressure inlet water. Low pressure reduces the RO permeation that tends to concentrate the dissolved salts. A better rinse might be performed with pressurized permeate water if a line can be plumbed back to the RO from a permeate storage tank system. The permeate is biostatic; its use reduces the formation of biological solids within the RO while shut down.
Membrane Fouling
Fouling doesn’t necessarily reduce RO membrane life if the RO is effectively cleaned. If the RO is allowed to foul too severely and cleaning is not effective, then the membrane will likely continue to lose performance. It is common to include a filter housing on the RO system inlet that contains 2.5-inch-diameter cartridge filters (Figure 3), whose pore size is nominally rated. The actual ability to remove smaller particles can vary greatly. Some (regardless of rating) only protect the RO against large particles that might get caught within the membrane flow channels or damage the high-pressure pump. These are inexpensive and may last weeks before an elevated pressure drop indicates the need for replacement. Tighter porosity filters that can remove more of the incoming suspended solids are more expensive and also require more frequent replacement. Therefore, the use of these tighter filters becomes more economically viable if the concentration of suspended solids in the water has been minimized by upstream treatment.
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It is common to include a filter housing on the RO system inlet that contains 2.5-inch-diameter cartridge filters. The filters shown here are fouled with various particles. Tighter porosity filters that can remove more suspended solids are more expensive and require more frequent replacement. Courtesy: U.S. Water Suspended solids can often be effectively reduced to reasonable concentrations for the downstream RO system with just a multimedia filter. Its inclusion in the RO water system might be sufficient to prevent a high RO fouling rate that could result in unmanageable cleaning requirements. Multimedia filters contain granules of two or more different types or sizes of sand, crushed rock, or anthracite (a hard form of coal). Such a filter can be successful at removing most of the particles that make up the suspended solids if: the Analyst Volume 25 Number 3
Design and Care of Reverse Osmosis Systems continued
It is sized for a downward flow velocity approaching 2 feet per second. It has a lower collection lateral system designed to obtain uniform flow distribution across the media when the filter is operated at low flow velocity, while also allowing the entry of a sufficient backwash flow rate for a 40% bed expansion. The filter is backwashed before its previously removed smaller/fine particles are shed, which may occur before there is an appreciable buildup in filter pressure drop. After backwashing, the filter is forward-rinsed at its service flow rate until its effluent quality is acceptable (such as based on effluent iron concentration, turbidity, or SDI). The preceding points do not provide all the filter design requirements but were chosen because these particular guidelines are often not followed (mostly because they would increase the filter’s cost). Some water sources may contain unusually high concentrations of fine particles. In these cases, it may be necessary to send the water through large reaction tanks intended to give the particles more time to coagulate into larger particles that can then be more easily filtered. An inorganic chemical coagulant (never a cationic polymer) may be added to the water upstream of the tank to speed the coagulation process. The coagulant is most effective if it is first well mixed with the suspended solids. If soluble metals (such as iron or manganese) are present in the water source, some percentage will be oxidized by allowing the water to contact atmospheric air in the tank, although this percentage is typically small. A chemical oxidizer such as chlorine (bleach) can be added to the water to oxidize the metals into their insoluble oxides (actually into their hydroxides when present in water) prior to coagulation.
Therefore, these systems may be used as an alternative to multimedia filtration, or possibly downstream to further polish the water and minimize RO fouling. The most common configuration is hollow-fiber technology. Fibers of an inert polymer are extruded with a hollow internal region, or lumen. The fibers may be relatively fine/small in diameter where the inlet water passes around the outside of the fibers, and through the fiber wall to the fiber lumen. It then moves toward one end of the module for collection. Because the fibers are tightly packed, flow movement around them is not uniform. Feedwater particles will come out of suspension on the membrane surface as the water goes through the fiber. They are not concentrated within a passing stream, as the particles mostly would be with spiral-wound RO, so there is no concentrate stream. The systems are simply operated at 100% recovery, except for the water losses from frequent backwashing with filtered water, resulting in an overall recovery of 90% to 95%. There also are modules with larger fibers that use an inside-out service flow direction. The fatter fibers offer improved membrane surface flow characteristics for better distribution of the fouling solids, while the finer fibers offer the cost advantages of more membrane surface area in the modules. The membrane filtration systems (Figure 4) should be sized to keep the fiber pressure differential (transmembrane pressure, TMP) relatively low to prevent compaction of solids against the fiber and into the fiber pore structure, and to reduce the potential for fiber breakage. This may mean sizing the fiber for a filtrate flux rate of 30 gallons per square foot per day or less.
Membrane Filtration
Membrane filtration is becoming more common in various applications, including pretreatment for RO systems. It can often provide water that is more consistently low in its concentration of suspended solids than that provided by a pressurized multimedia filter.
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the Analyst Volume 25 Number 3
Design and Care of Reverse Osmosis Systems continued
Figure 4. Automated membrane filtration system.
Figure 5. Doubling up.
The system shown here can be used as an alternative to multimedia filtration, or downstream to further polish the water and minimize RO system fouling. Courtesy: U.S. Water The fiber modules are backwashed using the filtrate water at a frequency of roughly once every 30 minutes, again, to try to keep the solids from compacting and to prevent particles from getting forced into the pores and subsurface structure. Some manufacturers reduce the backwash volume by knocking the solids free with compressed air. Backwashing alone may not fully restore the original TMP, and a chemically enhanced backwashing may be required. If this fails to restore original performance, a circulated cleaning for an extended period of time may be needed.
Operation and Monitoring
Large RO systems include a number of membrane pressure vessels, which are staged so that the concentrated salt stream from one set of parallel-plumbed vessels is plumbed into a smaller number of membrane vessels, then possibly plumbed to another stage with an even smaller number of vessels (Figure 5). This staging is based on maintaining flow velocities sufficient to keep suspended particles moving and to assist dissolved salts in diffusing back into the bulk stream from the membrane surface.
20
A two-pass RO system purifies the raw water twice and requires essentially twice the control valves and monitoring instrumentation as a single-pass system. Courtesy: U.S. Water RO systems are usually operated by adjusting the membrane feed pressure as needed to achieve the desired RO permeate flow rate. This may be done with a variable frequency drive (VFD) to control the high-pressure pump motor’s rotational speed, or by using a throttle valve located directly downstream of the pump. With VFD control, the adjustment may be automatic. The RO system also has a concentrate stream throttle system to achieve the desired concentrate flow rate. This may be a fixed system that uses an orifice plate, or more commonly a manual or automatic valve.
the Analyst Volume 25 Number 3
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Design and Care of Reverse Osmosis Systems continued
Along with the permeate and concentrate flow meters, pressure sensors are installed in the system piping to monitor the pressure entering the membrane elements, the concentrate pressure exiting the membrane, and possibly the pressures within the plumbing manifolds that connect the membrane vessel stages. A permeate pressure sensor may be needed, especially if there is significant or variable permeate backpressure on the system. The electrical conductance of the water streams is used to monitor how well the RO is removing dissolved salts. The RO permeate water conductivity is monitored along with the makeup water conductivity. A percent salt rejection for the system is calculated by subtracting
the permeate conductivity from the feed stream conductivity and then dividing this value by the feed conductivity. The salt rejection percentage is probably the most commonly monitored performance variable. Additional instruments (Figure 6) may be needed if there is variability in the feedwater characteristics, or if a chemical is added. If the water acidity changes naturally or through chemical addition, then the water pH should be continuously monitored. The pH can have a dramatic impact on the RO salt rejection. If chlorine is being removed upstream, an online chlorine monitor or possibly an oxidation-reduction potential (ORP) monitor may be used to warn against its presence.
Figure 6. Siting the monitoring instruments.
Depending on system location, and its installation configuration, monitoring instruments may be panel-mounted or mounted directly on system piping. Courtesy: U.S. Water
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the Analyst Volume 25 Number 3
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Design and Care of Reverse Osmosis Systems continued
Key RO System Variables
Monitoring the percent salt rejection is important but is limited in its ability to show the state of the RO membrane, and it is generally not a good gauge of membrane fouling or scale formation. The relative ability for water to permeate the RO membrane can be tracked (Figure 7) using a variable called the normalized permeate flow rate, which is the RO permeate flow rate standardized for the effects of operating pressures, dissolved salt content, and water temperature. The feed-to-concentrate pressure drop tracks the resistance to water passage through the flow channels of the various membrane elements. This value may be calculated for the entire RO vessel array, or if
interstage pressures are available, it can be calculated for the individual vessel stages. If flow rates are not kept constant when operating the RO, it is necessary to standardize the pressure drop for the effect of changing flow rates in calculating normalized pressure drop values. This then allows direct comparison of these values over time, regardless of whether any flow rates have changed. Small suspended particles or salt particles that coat the RO membrane surface can cause the RO normalized permeate flow rate to decline (Figure 8). Larger particles that get caught within the membrane flow channels and subsequently block the flow will cause the normalized pressure drop to increase.
Figure 7. A stable RO system.
This graphic shows the performance variables of a stable RO system, with normalized permeate flow and normalized differential pressure in psi, over a 215-day period. Courtesy: U.S. Water
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the Analyst Volume 25 Number 3
Design and Care of Reverse Osmosis Systems continued
Figure 8. Declining normalized permeate flow rate.
This chart provides information about an RO system with a declining normalized permeate flow rate, as tracked over 194 days. Courtesy: U.S. Water If something in the water is chemically reacting with the RO membrane, the effect will likely be apparent in the normalized permeate flow rate, and possibly in the salt rejection. For example, if chlorine is allowed to come into contact with the RO membrane, the extent of membrane oxidation is apparent as an increase in the normalized permeate flow rate, soon followed by a decline in RO salt rejection. A thorough understanding of the state of the RO system can be gained by routinely calculating and graphing the salt rejection and the two normalized performance variables, though their values may be misleading if any of the instrument readings are inaccurate. It is critical that monitoring instruments be routinely calibrated and repaired/replaced if in error.
Frequency of System Cleaning
Chemical cleaning is a routine requirement for most RO systems; the frequency depends on the effectiveness of the pretreatment equipment. As fouling solids or scale particles accumulate, their characteristics often change and 25
they become more resistant to cleaning. Clay and biological materials tend to compress against the membrane surface and become chemically resistant as water is squeezed out of their structure. Scale formations may change from being primarily calcium carbonate (relatively easy to clean) to calcium sulfate (difficult to clean). The change in normalized RO performance variables can be used to determine cleaning needs. Most membrane manufacturers recommend cleaning before these variables change by about 15%. Certain types of fouling solids or scaling salts may have a substantial impact on permeate quality. Aluminum salts may come out of suspension as a fouling particle, only to redissolve if the water acidity changes. This can result in increased aluminum passage from the membrane surface through the membrane and into the permeate/purified water. Calcium carbonate scale may leach a relatively high concentration of calcium carbonate through the membrane into the permeate stream and affect the conductivity. Most other fouling the Analyst Volume 25 Number 3
Design and Care of Reverse Osmosis Systems continued
solids don’t have a significant impact on RO salt rejection unless the fouling is extreme.
How to Clean a System Membrane
Membrane cleaning involves passing a cleaning solution through the membrane system at conditions that promote the dissolution or delamination of the fouling solids from the membrane surface, or from the spacing material along the membrane flow channels. The optimum solution depends on the particular fouling solids or scale particles, and the relative ability to clean is often limited by membrane chemical tolerance. Most strong oxidizing agents that are typically effective in cleaning biological solids are not compatible with RO membranes. There are also limits to the pH extremes that should be used. In addition, while higher temperatures increase the rate of cleaning, the solution temperature is limited to less than 105 °F or as designated by the membrane manufacturer. The most critical characteristic of a cleaning solution is its pH. Acidic solutions are more effective in dissolving metals and scale formations, while alkaline (high pH) solutions are more effective in removing clay, silt, biological, and other organic solids. Strongly acidic solutions may stabilize biological solids and should not be used as a first cleaning step. Finishing a cleaning with a strongly acidic solution tends to leave the membrane with increased rejection characteristics but reduced permeate flow, while finishing with a strongly alkaline solution has the opposite effect. The addition of specific cleaning agents often improves the solution’s cleaning abilities. A chelating agent assists in extracting metals from the fouling solids, while surfactants/detergents improve the solution’s ability to penetrate the fouling solids and suspend oily substances. The use of surfactants may reduce cleaning time, but increases the time required for rinseup. When the fouling solids cause a flow restriction, increasing normalized pressure drop, high cleaning flow rates (within the membrane manufacturer’s guidelines) through the membrane feed channels cause agitation that assists in breaking up the deposits. When the solids coat the membrane surface and reduce the
26
normalized permeate flow rate, the delamination of these solids is best achieved by cleaning at low pressure, so that water does not permeate through the membrane during the cleaning process, creating a force that holds the solids to the surface. Achieving a high cleaning flow rate that is balanced throughout all the membrane vessels usually requires each vessel stage to be cleaned separately. This also helps minimize the pressure required to push the solution through the elements. Cleaning solution should be pumped at high flow rates, as recommended by the membrane manufacturer, and pumped at the maximum pressure required to achieve the target flow rate—but this may be limited to 60 psi to reduce the potential for crushing or otherwise damaging the membrane elements. The solution is directed in the normal feed-end direction of flow and the exiting concentrate stream is then returned to the cleaning tank at minimal backpressure. The flow direction may occasionally be reversed so that the solution enters the concentrate end of the stage when fouling solids are blinding the face of the lead-end membrane elements. There may be a small flow of permeate that should also be returned to the cleaning tank using a separate line. In spite of its low apparent flow rate, the permeate should never be valved off because this may put certain membrane elements at risk of physical damage. Data should be recorded during the cleaning process. With membrane surface fouling, it is difficult to gauge when original performance has been restored until the unit is rinsed and operated normally. If the fouling solids were causing an increased pressure drop in the RO, then the cleaning inlet pressure can be used as a measure of cleaning progress. If the pressure keeps declining, the cleaning is still removing fouling solids. If the fouling is severe, it may require a number of hours of circulation before the inlet pressure stabilizes. Cleaning success is confirmed when the normalized pressure drop, and normalized permeate flow rate, return to their startup values.
the Analyst Volume 25 Number 3
Design and Care of Reverse Osmosis Systems continued
Conclusion
Silica is poorly ionized at neutral pH and has limited solubility. Membrane and precipitation processes can be quite effective at elevated pH but are either ineffective or less than wonderful at neutral pH. Demineralizers, with hydroxide-form anion resin, remain one of the best methods for removing silica, especially when TDS removal is also required.
Removal of silica without also removing all the other ions is far more problematic, and there are no wonderful methods in the water treatment engineer’s toolbox. Of the less than wonderful ways, ion exchange remains one of the available treatment methods, directly applicable as pretreatment to other unit processes or as a standalone method of removing silica along with other ions. Wes Byrne is a membrane technologies consultant for U.S. Water Services and can be reached at (612) 741-2001 or wbyrne@uswaterservices.com.
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DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers Linna Wang, Claudia C. Pierce, Dorothy Reynolds, Suez Water; and Elizabeth Summer, Ecolyse, Inc.
Introduction Background on WCT Microbial Issues Cooling processes use water as a heat sink, flowing over and through pipes and surfaces with many areas exposed to ambient conditions and environmental nutrients, not to mention nutrients stemming from industrial processes themselves. This creates an environment where microorganisms thrive and will take advantage of systems that are not maintained with proper chemical treatments.1 Microbiological activity causes a number of issues, with some particular problem areas in a cooling tower, including fouling, corrosion, and the spread of aerosolized pathogens. One of the major issues caused by organism accumulation is a reduction of heat exchanger efficiency due to the insulating characteristics of biofilm growth, which also can restrict water flow or lead to full plugging of these tubes.1 Microbial influenced corrosion and pitting are more likely to occur in tubes and pipes containing biofilm due to the creation of chemical gradients and anaerobic conditions.2 Algal mats can form on open deck systems, restricting water flow, and in water lines, creating clogs. Tower fill encompasses a lot of surface area, is open to ambient air, and, with drift water contacting contaminated surfaces, creates potential health concerns. Organisms will also contribute to biodeterioration of wooden components in a cooling tower. There are also potentially pathogenic organisms, which, if captured in tower drift, may become aerosolized. In industry, a typical approach to microbial control is through the generic application of chemical biocides. However, bacteria simply do not always respond in a uniform, predictable fashion to chemicals. In medicine, identification of the problem bacteria is sometimes needed to identify an effective antibiotic; similarly, biocides do not always work effectively in every application. Biocide sensitivity impacts many industries and sectors of society, including oil and gas, water treatment, food, personal hygiene, and health.3-9 The root cause of response variation can be complex. In some cases, the cause is due to incompatibility of the biocide with the system chemistries. Additionally, intrinsic structural and physiological differences between organisms give rise to various susceptibilities. The sensitivity to biocides is also impacted by growth in a biofilm, and changes are observed depending on the species composition of the 29
biofilm. Certain bacteria are more likely to produce the extracellular components of the biofilm (e.g. exopolysaccharides, which form a protective gelatinous film over organism). Others might produce acidic byproducts and inhabit areas under biofilm where they are protected and closest to metal surfaces, making damage likely. In other situations, the toxic nature of chemical biocides is contrary to their application (e.g., waters that may re-enter the environment). The primary concern of industries is the efficient removal and control of potentially problem-causing organisms, as opposed to details on the types of organisms. However, control and knowledge of the problem organisms cannot always be separated. Growing evidence suggests that different types of bacteria respond very differently to chemical control agents. Therefore, in the interest of developing better microbial control methods, knowledge of the types of organisms causing the problem is paramount. Application of microbial population analysis tools based on amplification metagenomics has revolutionized understanding of bacteria in health, ecology, and other industries.2,10 This understanding includes information on the types of water cooling tower (WCT) associated bacteria, the relative abundance of each different type of bacteria (i.e., which types of bacteria dominate a given population of a WCT systems), the absolute abundance (i.e., number of cells per milliliter of water, gram of solids, or centimeter of surface area), and how similar the different facilities are. A systematic, broad analysis of microbial populations in WCT using an amplicon metagenomics approach has, to the best of our knowledge, not been conducted. This will better allow for predictive tools to follow the specific types of bacteria that are responsible for microbial-associated issues. The purpose of this study was to gain a broad perspective on microbial population structures across a spectrum of WCTs, as well as multiple samples within a single WCT. This information can be used to gain a real understanding of the targets of microbial control in WCT. Toward this end, an amplicon metagenomics approach was employed on 40 samples isolated across broad geographical and WCT types. This analysis provides a framework with which to plan the types of microbial control strategy that can be applied across a wide range of WCT, as well as to better understand the potential values of species targeted antimicrobials. the Analyst Volume 25 Number 3
DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers continued
Experimental Procedure
Results
Sample Descriptions Sample Collection and Storage WCT liquid samples were collected into clean, new polypropylene bottles, filled to the brim. Sessile samples included solids debrided from the sides of structures, sediments from the bottom of pools, or biofilms formed on corrosion coupons. Solid samples were packed in liquids obtained from the same location. All samples were kept at 4 oC and processed immediately upon arrival at the lab. DNA Isolation and 16S Amplicon Metagenomics Total environmental DNA was isolated from each sample. To do this, the bacteria were concentrated by centrifugation or filtration. DNA was isolated using a bead-beating approach, during which chemical and physical disruption of the cells is accomplished by incubation under strong denaturing conditions and maceration by vortexing in the presence of ceramic beads. The isolated DNA was column purified, and subjected to bacterial tag-encoded FLX amplicon pyrosequencing (bTEFAP).10 Resulting sequences were trimmed and quality scored. All sequences passing the quality score were compared using BLASTn to a ribosomal database to make a classification. Identity values were used to make assignments to the appropriate taxonomic levels based on the following cutoffs: Sequences with identity scores, to known or well characterized 16s sequences, greater than 97% identity (<3% divergence) were resolved at the species level, between 95% and 97% at the genus level, between 90% and 95% at the family level and between 85% and 90% at the order level, 80 and 85% at the class level and 77% to 80% at phyla level.
A total of 40 samples, including 25 planktonic and 15 sessile samples, were collected from 12 WCT facilities (Table 1). Sample collecting and sequencing occurred between 2012 and 2014. The selection of WCT varied in geographical location, design, volume, and type of facility serviced. Geographically, the WCT samples included single facilities located in Ontario, Canada; Rhein, Germany; the states of Kansas, Maryland, New Jersey, Ohio, Pennsylvania, and South Carolina; and four cities in Texas. About half (19) were collected from WCT servicing industrial plants, primarily refineries. The remaining samples include eight collected at five different WCT within a large academic institution and 13 samples collected from a WCT servicing large commercial buildings. Within each location, samples were taken from collection ponds, makeup waters, and recirculation or sump water, as well as from sessile samples growing on coupons or solids from the location. For 11 of the sessile samples, 1-cm stainless steel biostuds were installed onto Robbins devices connected to recirculation waters at each site and allowed to circulate for varying lengths of time prior to analysis. For sampling, bacteria and DNA were isolated from the Robbins device coupons as well as associated fluids. The four sediments, including sludge and sand, were collected from the bottom of the collection pond for three of the samples. Planktonic samples included any flocculant in the materials recirculating water.
Physiological Annotations Physiological assignments were made based on analysis of the data available for the most closely related organisms.
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the Analyst Volume 25 Number 3
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DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers continued
Table 1. Water Cooling Tower Sample Summary
Bacterial Diversity in WCT DNA was isolated from each of the WCT samples. The DNA yields ranged from 0.7 ng/ml to over 5 mg/ml of sample. When converted to bacterial cells per ml, using a conversion factor of 3.3 X 105 bacterial cells per ng DNA, these DNA yields corresponded to between 105 to 109 bacterial cells per ml. Note that this calculation does not take into account that DNA recovery is not 100% and also that at least some of the DNA could originate from nonbacterial sources, such as algae. Both of these factors impact the accuracy of using DNA yields to calculate bacterial load. The isolated DNA was subject
32
to 16S amplicon metagenomic analysis. Following quality scoring and trimming, between 1,058 and 21,362 sequences were generated per sample. These were compared to a RNA sequence database and assigned species annotations. A total of 1,755 bacterial taxa were annotated. On a per sample basis, the number of taxa clusters ranged from 15 in sample I.1 to 519 in sample I.7 (Table 2). The ratio of the number of sequences to the number of taxa generated ranged from 0.007 to 0.08 (Table 2, data not shown). Table 2 provides a summary of the number of sequences and the number of unique taxa obtained from each sample.
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DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers continued
Table 2. Number of Bacterial Taxa Identified in 40 Water Cooling Tower Samples
Type is the type of sample (P, planktonic; S, sediments; B, biostud), # Seq = number of sequences, # Taxa = number of bacterial taxa. Total is the total for all samples. Note that the total number of unique taxa is not additive because some taxa are present in more than one sample. “Per Avg” is average number of sequences and number of taxa per sample. identified in the sample are predicted to be involved Of the 1,755 bacterial taxa, 566 were given genus in widespread metabolic and physiological processes, designations but not species designations because the including nitrogen cycling, degradation of xenobisimilarity to known species was not high enough. These otics or atypical substrates such as cell wall materials, organisms are indicated as Genus sp. The four most photosynthesis, biofilm formation, iron reduction, widespread bacteria were annotated as Psuedomonas sulfidogenesis, and acid production (Table 3). sp., Acidobacterium sp., Flavobacterium sp., and Hydrogenophaga sp (Table 3). Each of these contains subclusters of sequences that are distinct enough to be different species. This indicates that bacterial C O R P O R AT I O N diversity is even higher than what is ® Environmentally Safe VpCI /MCI Technologies indicated here. In all, 823 genera and 57 bacterial classes were identified in the samples. More than 93% of all species identified in the 40 samples were members of one of 16 different Cortec® VpCI® water treatments give you the green building blocks to classes, including numerous represtop scale and corrosion during system operation. VpCIs can be added sentatives of Gammaproteobacteria, to your current treatment program as a liquid or powder. They are ideal Betaproteobacteria, for both closed and open loop systems, providing a complete inhibitor package for multi-metal protection and scale inhibition. Cortec® VpCIs Alphaproteobacteria, replace nitrites, amines, phosphates, azoles, molybdates, and other Deltaproteobacteria, Cytophagia, corrosion and scale inhibitors. For protection against bacteria, ask Flavobacteria, Clostridia, about Cortec’s green bio-dispersant. Sphingobacteria, and Verrucomicrobia (Table 3, data not shown). Bacteria Q U A EXCELLENCE I T Y
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the Analyst Volume 25 Number 3
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DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers continued
Table 3. Bacteria Identified Present in at Least 15 of 40 WCT Samples Class
Species
# WCT
Avg %
Characteristics of Interest
Gammaproteobacteria
Pseudomonas sp
36
7.34
Various, i.e., GHB, Biofilm, etc.
Acidobacteriia
Acidobacterium sp
34
14.94
APB, unknown
Flavobacteriia
Flavobacterium sp
31
8.01
Biodegradation
Betaproteobacteria
Hydrogenophaga sp
31
2.99
Biodegradation
Betaproteobacteria
Acidovorax sp
28
0.65
NRB, denitrifying
Betaproteobacteria
Methylophilus sp
28
8.00
Methylotroph
Alphaproteobacteria
Sphingomonas sp
27
1.14
Biodegradation, GHB
Cytophagia
Flexibacter sp
26
0.46
Biodegradation
Alphaproteobacteria
Rhodobacter sp
25
0.98
Photoautotroph
Gammaproteobacteria
Legionella sp
24
0.63
Unknown
Deltaproteobacteria
Bdellovibrio sp
23
0.26
Bacterial predator
Alphaproteobacteria
Bradyrhizobium sp
23
0.35
Nitrogen fixing
Alphaproteobacteria
Caulobacter sp
23
0.59
GHB
Clostridia
Eubacterium sp
23
2.30
Fermentative acetogen
Alphaproteobacteria
Porphyrobacter sp
23
3.60
Photoautotroph,biodegradation
Gammaproteobacteria
Thermomonas sp
23
0.60
NRB, denitrifying
Unclassified
Aquabacterium sp
22
0.85
Biofilm Steel
Betaproteobacteria
Comamonas sp
22
0.48
Biodegradation PAH denitrifying
Alphaproteobacteria
Hyphomicrobium sp
22
0.65
GHB
Betaproteobacteria
Methylobacillus sp
22
0.24
Methylotroph
Cytophagia
Cytophaga sp
21
1.51
Biodegradation GHB, biofilm
Gammaproteobacteria
Pseudomonas aeruginosa
21
5.67
Gammaproteobacteria
Acinetobacter sp
20
1.86
Biodegradation
Gammaproteobacteria
Aquimonas sp
20
0.76
GHB
Clostridia
Clostridium sp
20
0.82
Diverse, fermentative
Unclassified
Leptothrix sp
20
0.24
Filamentous, Mn(II)OX MIC
Alphaproteobacteria
Mesorhizobium sp
20
0.17
Nitrogen fixing
Alphaproteobacteria
Parvibaculum sp
20
0.33
Biodegradation, alkanes
Alphaproteobacteria
Porphyrobacter tepidarius
20
5.25
Photoautotroph, biodegradation
Alphaproteobacteria
Rhizobium sp
20
0.21
Nitrogen fixing
Betaproteobacteria
Methylovorus mays
19
0.65
Methylotroph
Alphaproteobacteria
Novosphingobium sp
19
3.85
Biodegradation
Sphingobacteriia
Sphingobacterium sp
19
0.27
GHB aerobe
Verrucomicrobiae
Verrucomicrobium sp
19
0.45
Fermentative
Deltaproteobacteria
Geobacter sp
18
0.33
IRB
Betaproteobacteria
Ralstonia sp
18
0.64
Biodegradation
Unclassified
Reyranella massiliensis
18
0.55
Unknown
Gammaproteobacteria
Stenotrophomonas sp
18
0.28
Biofilm
Unknown
Uncultured bacterium
18
1.61
Unknown
Gammaproteobacteria
Aeromonas sp
17
4.44
Biofilm
Gammaproteobacteria
Alcanivorax sp
17
0.51
Biodegradation
Bacilli
Bacillus sp
17
0.13
Diverse, GHB, biodegradation
Gammaproteobacteria
P. pseudoalcaligenes
17
0.75
GHB, biofilm
Betaproteobacteria
Sterolibacterium sp
17
0.15
Biodegradation denitrifying
TM7 (class)
TM7 uncultured
17
1.12
Unknown
Betaproteobacteria
Acidovorax delafieldii
16
1.00
Biodegradation
Betaproteobacteria
Alcaligenes sp
16
0.39
NRB
36
the Analyst Volume 25 Number 3
DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers continued
Alphaproteobacteria
Blastomonas sp
16
0.29
CT Unknown
Gammaproteobacteria
Cellvibrio sp
16
1.18
Flavobacteriia
Chryseobacterium sp
16
5.05
Biodegradation
Betaproteobacteria
Denitratisoma sp
16
0.30
NRB, denitrifying
Gemmatimonadetes
Gemmatimonas sp
16
0.22
GHB, oligotroph
Unclassified
Methylibium sp
16
0.38
Methylotroph
Gammaproteobacteria
Methylophaga sp
16
0.25
Methylotroph
Betaproteobacteria
Methyloversatilis universalis
16
5.30
Methylotroph
Gammaproteobacteria
Rheinheimera sp
16
2.04
Unknown
Betaproteobacteria
Variovorax sp
16
0.67
Biodegradation, phenol, TCE
Cytophagia
Algoriphagus sp
15
0.37
GHB, biodegradation
Gammaproteobacteria
Alishewanella sp
15
0.26
Sulfidogen
Gammaproteobacteria
Aquimonas voraii
15
0.22
Biodegradation
Betaproteobacteria
Azoarcus sp
15
0.45
Biodegradation, PAH, denitrifying
Deltaproteobacteria
Bdellovibrio bacteriovorus
15
0.31
Bacterial predator
Alphaproteobacteria
Brevundimonas sp
15
0.32
Biodegradation
Chlamydiia
Chlamydia sp
15
0.67
Endosymbiont
Betaproteobacteria
Delftia sp
15
0.74
Biodegradation, phenanthrene
Chlamydiia
Parachlamydia acanthamoebae
15
0.11
Endosymbiont
Chlamydiia
Rhabdochlamydia crassificans
15
0.42
Endosymbiont
Gammaproteobacteria
Shewanella sp
15
0.30
IRB, sulfidogen, MIC
Betaproteobacteria
Thauera sp
15
0.32
NRB, biodegradation
Betaproteobacteria
Thiobacillus sp
15
1.66
APB, SOB
Table 3 abbreviations: # WCT is the number of WCT samples that the indicated organism was identified in. Avg % is the average percent abundance in any samples. Characteristics of Interest are select characteristics of that type of bacteria. APB, acid producing bacteria; GHB, general heterotrophic bacteria, MIC, microbial influenced corrosion; NRB, nitrate reducing bacteria; SOB, sulfur oxidizing bacteria; IRB, iron reducing bacteria. The majority of bacterial species were present in only a few samples. Bacteria were categorized by select physiological or metabolic traits to determine the distribution and abundance of potentially problematic bacteria (Table 4). Bacterial physiologies associated with corrosion include acid production, sulfidogenesis, and iron reduction. Sulfidogenic bacteria, capable of sulfide generation either from sulfate reduction or other pathways, were detected in 35 of the samples. Over 70 species of sulfidogenic bacteria, including 41 true SRB, were identified in 35 of the 40 samples tested. Representative SRB genera included Desulfovibrio, Desulfomicrobium, Desulfobacter, Desulfobotulus, and Desulfoglaeba (Table 4). Since true SRB are strict anaerobes, it is likely that these bacteria were associated with anaerobic microenvironments, such as in biofilms or floc. IRB are associated with metal corrosion. There were 43 species of IRB present, primarily different Geobacter and Pelobacter isolates. IRB were found in 27 of the 43 samples. Inorganic acid production, usually through sulfur oxidation, is associated
37
with concrete degradation. Important inorganic acid producing bacterial genera, including Thiobacillus strains, were found in 26 of the 40 samples. When present, sulfidogenic, IRB, and inorganic acid producing bacteria did not constitute a significant proportion of the bacterial population, each usually comprising less than 1% of the total population of bacteria (Table 4). Data on these organisms in oil and gas systems, where their impact is most well studied, suggests that even these low concentrations might be enough to pose a threat to structures (2, 13). Organic acid bacteria typically produce acids as a result of fermentation. When present, organic acid bacteria constituted, on average, 7.6% of a given population. Organic acids are a common product of microbial fermentation under reductive conditions, which can be found in bottom layers of a biofilm, decreasing pH near metal surfaces and causing metals to dissolve. Formation of organic acids also supplies rich nutrients into deep layers of biofilm, which can be readily utilized by SRBs to create more aggressive corrosion.
the Analyst Volume 25 Number 3
DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers continued
Table 4. Distribution and Relative Abundance of Potentially Problematic Bacterial Types
Bacterial Relative Abundance and Distribution To better understand the impact of bacterial diversity on WCT functioning, the basic parameters of bacterial population structure needs to be determined. Two basic pieces of information about bacterial population structure are 1) the number of different types of unique species in a given sample (absolute diversity) and 2) the relative abundance (e.g., the relative proportion of each bacteria to each other, as a % abundance in the population). For the 40 WCT populations tested here, the number of species identified in each sample varied from 15 to 519, with an average number of species per sample of 155. Not every species was present in every sample. On average, each species was found in 3.5 of the 40 samples. The distribution of species across all samples was found to vary considerably (Table 5). Of 1,755 species, 697 were found in only one of the 40 samples, and 1,619 were found in fewer than 10 samples. Conversely, only 4 species were found in more than 30 samples, with one species of Pseudomonas that was present in 36 samples being the most widely distributed. The four most widely distributed species were identified as Pseudomonas sp., Acidobacterium sp., Flavobacterium sp., and Hydrogenophaga sp., which were present in 36, 34, 31, and 31 samples, respectively.
38
Table 5. Distribution of 1,755 Species Across 40 WCT Samples Number of samples in which each species is present
Number of Species
% of Species
30 to 40 samples
4
0.23
20 to 29 samples
26
1.48
10 to 19 samples
106
6.04
1 to 9 samples
1619
92.25
40 samples
1,755 species total
Average Species/Sample: 155 species/sample Average Samples/Species: 3.5 samples/species
Most of the different types of bacteria in each sample were present as only a small fraction of the total biomass of bacterial cells (Figure 1). Each of these “low abundance” types of bacteria constituted less than 1% of the population, meaning for every 1,000 bacterial cells in the sample, less than 10 of them were the indicated species. The “medium abundance” types of bacteria each contributed 1% to 10% of the biomass of bacteria, and “high abundance” types of bacteria made up more than 10% of the bacterial biomass. When each bacterium in a sample was classified as “low abundance,” “medium abundance,” and “high abundance,” it was found that most of the types of bacteria in each sample were considered “low abundance,” with sample l.1 being the only exception (Figure 1). Taken together, the information on distribution and relative abundance suggests that most of the genetic diversity in WCT samples is present in “low abundance” organisms; that is, those making up less than 1% of the total biomass of the population. Because they are low abundance, the sequence coverage for most samples is not sufficient to robustly identify them in every sample. It is possible that the species are more widespread than indicated by these data, but much higher sequence coverage is needed to detect them. the Analyst Volume 25 Number 3
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DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers continued
Figure 1. The Relative Abundance of Each Species in Each Sample
Comparison of Population Structures Between Different Samples The next basic question on population structures is to ask how similar each population is to one another. One indicator of population similarity is how similar the two populations are in terms of how many shared organisms they have.11 The population consortia of the different samples were also compared using the Diceâ&#x20AC;&#x2122;s coefficient, Equation 1, where C is the number of species shared between the two samples, and A and B are the number of species in samples A and B.9, 10
D=[2C]/[A+B] (1)
The assumption is that populations that share a greater percentage of species in common are more similar to each other. A limitation of this calculation is that it is not weighted for relative abundance of the shared organisms. Dice coefficient values range between zero and 1, where a value of 1 indicates the two samples are identical, such as when a sample is compared to itself. The 40 WCT samples were compared to each other using the Dice coefficient (Figure 2). When all organisms, regardless of percent abundance in the sample, were compared, the overall pair-wise sample similarities
40
were low, with an average value of 0.2, indicating that on average each sample shared less than 20% of potentially shared species in common with any other sample (data not shown). To reduce the impact of low sequence coverage, the values were recalculated using bacteria present in at least 1% of a sample. This resulted in an average pair-wise similarity value of 0.4 (Figure 2). Overall, samples from within a single WCT, or geographical location, were more similar to each other then they were to WCT from other geographical locations, with an average intra WCT value of 0.5. There were nine paired planktonic/sessile samples: A.1p/A.2s; B.1p/B.2s; B.4p/B.5s; D.1p/D.2s; F.1p/F.2s; H.1p/H.2s; I.8p/I.6s, I.7s; J.1p/J.2s; L.11p/L.8s, L.9s, L.10s. The average value for paired coupon and sessile samples was 0.7, indicating that the most similar populations of bacteria analyzed were the cognate biofilm and planktonic samples from a single location (Figure 2). Sample sets I and L included multiple samples from different WCT within a single geographical location. Paired sessile/biofilm samples were more similar to each other than they were to samples collected from different WCT within the same geographical location.
the Analyst Volume 25 Number 3
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DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers continued
Figure 2. Pair-Wise Comparison of Bacteria in 40 WCT Samples
Figure 2 shows a 40 by 40 grid, with the Dice coefficient value for each population compared against every other population. The yellow diagonal indicates samples compared to themselves, which results in a value of 1 (100% identical). The remaining values are duplicated above and below the diagonal. Values are color coded as indicated. Boxed sample labels in the header row indicate the paired planktonic and sessile samples. Boxed values are the values for all samples collected from a single WCT, also indicated by the X-axis label (A through L).
Conclusions
This study included the analysis of a total of 40 samples comprising 12 different geographical locations. Having such diversity of locations proved to be a benefit but also had some downsides. The benefits include having a comparison of diversity from different states and even different countries. It could be seen if even a few organisms were abundant on a global or regional basis. It is much easier to make larger generalizations about particular organisms and their treatments if there is information related to prevalence. On the downside, it is more difficult to conduct a complete and thorough analysis
44
of so many locations, making the data not as complete. Still, much information was gained from the study, and some interesting observations were made. When just the comparison of the overall population structure in terms of distribution and relative abundance of bacteria in the samples is considered, results here parallel previous findings on bacterial populations from natural and industrial systems. Two generalities supported by independent analysis of multiple bacterial population data sets are that 1) the majority of different types of bacteria in a given sample are scarce (i.e., they constitute less than 1% of all bacteria in that sample), and 2) most of the bacterial types in any one sample are very limited in distribution (i.e., they are not likely to be detected in any other samples, even samples from the same field). However, the latter point might be an artifact of sequence depth, because as sequence coverage increases, the likelihood that low abundance speciess will be detected increases. These patterns were also evident in this study and suggests a generality that among organisms present in WCT, the bulk of genetic diversity is found in comparatively uncommon organisms, both in terms of absolute abundance as well as geographical distribution.
the Analyst Volume 25 Number 3
DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers continued
Of the 1,755 different species types detected in the study, 35 are considered to be in high abundance (over 1%), demonstrating the point above that the majority of organisms are in low abundance. This type of population, in which a few types of organisms dominate the system but there is a large diversity among low abundance organisms, has been seen in analysis of water samples taken from other industries, such as the oil and gas segment.2, 12, 13 This makes detection via standard plate count of the majority of organism types near impossible, as the most abundant organisms will always dominate the cultures. Organisms even at low abundance may act as a reservoir to take advantage of shifting conditions that become more favorable for proliferation and survival. It should be noted from historical data taken from the oil and gas industry that organisms need only be present at low levels ranging from 1% to 10% to become an issue, with an example being SRBs.2 Thus, detection of even low levels of bacteria is crucial to properly applying treatment to avoid the impact of, in this case, corrosion. Such high diversity with organisms even in low abundance is a lingering threat to systems that are not optimally treated due to both the intrinsic morphological variances in response to biocidal actives and the unique adaptive tolerance potential of each species. There were, however, four species found in more than 30 samples, with the top two in both abundance and prevalence across locations being acid producing bacteria and bacteria likely to lead to biofilm formation. When considering the organisms that have potential to cause issues in a cooling tower, biofilm formers and acid producers are two of the major culprits. Biofilm formers are less susceptible to biocide penetration due to their EPS generation potential. Biofilms also combine organisms with collective EPS barriers, which leads to a more protective environment for other organisms through the generation of anaerobic conditions and chemical gradients. Biofilmâ&#x20AC;&#x2122;s intrinsic resistance to biocides is due to the exopolysaccharide glycocalyx polymers, which allow adhesion to surfaces. Under these conditions biocides are forced through a diffusion gradient before reaching the organisms. Some Pseudomonas species are facultative anaerobes and can adjust from aerobic to anaerobic conditions and thrive above and below.
45
Biocide mechanisms of actions vary, and there is not a one-size fits all, particularly in light of the dynamic nature of organism tolerances. Of the general mechanism classes, there are oxidants, non-oxidant electrophiles, and membrane active chemicals. The oxidants include chlorine and peroxide and work from the outside in through free radical mediated oxidation. Electrophiles such as isothiazolones and glutaraldehyde react with intracellular nucleophiles on enzymes and cellular respiration. Some surface-acting mechanism biocides cationically react with anionic membranes to destabilize and cause leaking followed by cell death. Others act on surfaces through proton destabilization, such as what occurs with pyrithiones. Organisms react to varying degrees, depending on the ability to adapt to such stressors. Membrane protein alterations, efflux pumps, exclusion, and catalase and oxidase production are all examples. A common example is seen in the waterborne organism Pseudomonas making quats more difficult to penetrate the surface. Oxidants are susceptible to catalase- and oxidase-producing bacteria causing inactivation. Common practice is to combine free radical oxidizers with metabolic inhibitors or surfacing acting agents, the thought being that the organisms are not as likely to have multiple phenotypic changes at once. Testing for susceptibility to a variety of biocides at both the onset of a biocidal program as well as periodically is key to keeping the most optimized and cost-effective solution.
Acknowledgements
We would like to thank Matt Maddox, Chris Janes, and Geddy Hamblen for excellent technical support on this project.
the Analyst Volume 25 Number 3
DNA-Based Diversity Analysis of Microorganisms in Industrial Cooling Towers continued
References
1. W. Paulus, Microbicides for the Protection of Materials, (AA Dordrecht, The Netherlands: Springer; 2008) 2. E. Summer, S. Duggleby, C. Janes, M. Liu, "Microbial Populations in the O&G: Applications of this Knowledge," Proc CORROSION 2014, paper no 43763 (San Antonio, TX: NACE International 2014) 3. S.V. Sutton, D.W. Proud, S. Rachui, D.K. Brannan "Validation of Microbial Recovery from Disinfectants." PDA J Pharm Sci Technol, 56, 5 (2002): pp. 255-266
4. M. Periame, N. Philippe, O. Condell, S. Fanning, J.M. Pages, A. Davin-Regli, "Phenotypic Changes Contributing to Enterobacter Gergoviae Biocide Resistance," Lett Appl Microbiol, 61, 2: pp.121-129
5. A.D Russell, "Bacterial Adaptation and Resistance to Antiseptics, Disinfectants and Preservatives Is Not a New Phenomenon," J Hosp Infect, 57, 2 (2004): pp. 97-104 6. E. Giaouris, N. Chorianopoulos, A. Doulgeraki, G.J. Nychas, "Co-culture with Listeria Monocytogenes within a Dual-species Biofilm Community Strongly Increases Resistance of Pseudomonas Putida to Benzalkonium Chloride," PLoS One 8, 10, e77276
7. P. Sanchez-Vizuete, B. Orgaz, S. Aymerich, D. Le Coq, R. Briandet. "Pathogens Protection Against the Action of Disinfectants in Multispecies Biofilms,". Front Microbiol 6:705 8. E. Giaouris, E. Heir, M. Hebraud, N. Chorianopoulos, S. Langsrud, T. Moretro, O. Habimana, M. Desvaux, S. Renier, G.J. Nychas, "Attachment and Biofilm Formation by Foodborne Bacteria in Meat Processing Environments: Causes, Implications, Role of Bacterial Interactions and Control by Alternative Novel Methods," Meat Sci 97, 3: pp. 298-309
9. H.A. Videla, Manual of Biocorrosion, 1st ed (Boca Raton, FL: CRC Lewis Publishers, 1996)
10. S.E.Dowd, Y.Sun, P.R.Secor, D.D.Rhoads, B.M.Wolcott, et al., “Survey of bacterial diversity in chronic wounds using pyrosequencing, DGGE, and full ribosome shotgun sequencing,“ BMC Microbiol 8, 43 (2008)
11. L.R.Dice, "Measures of the Amount of Ecologic Association Between Species," Ecology 26, 3, (1945): pp.297-302
12. J. Fichter, K. Wunch, R. Moore, E.J. Summer, S. Braman, P. Holmes, "How Hot is Too Hot for Bacteria? A technical study assessing bacterial establishment in downhole drilling, fracturing and stimulation operations," Proc CORROSION 2012, paper no 01310 (Houston, TX: NACE International 2012) 13. J.B.Wrangham, E.Summer, “Planktonic Microbial Population Profiles Do Not Accurately Represent Same Location Sessile Population Profiles,” Proc CORROSION 2013, paper no. 02780 (Orlando, FL: NACE International, 2013)
Reproduced with permission from NACE International, Houston, Texas. All rights reserved. Author(s), Paper 9483 presented at CORROSION/2017, New Orleans, Louisiana. © NACE International 2017.
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the Analyst Volume 25 Number 3
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the Analyst Volume 25 Number 3
PBTC Revisited Robert J. Ferguson, French Creek Software, Inc. Richard Ashcraft, Athlon Solutions
48
the Analyst Volume 25 Number 3
Abstract
PBTC (2-phosphonobutane 1,2,4-tricarboxylic acid) has become the workhorse for calcium carbonate scale inhibition in cooling water, water reuse, and water treatment applications operating at the edge of control technology. Economically, this stressed system inhibitor allows cooling tower operation at higher concentration ratios, resulting in decreased water usage and discharge. The inhibitor also allows the reuse of water that would otherwise be discharged, possibly after costly treatment. It permits the use of less than desirable water in other applications. Performance and limits of this inhibitor were first characterized in a 1985 paper.1 This article expands these findings based on over 30 years of field application and recent laboratory studies to elucidate behavior and performance of this "go-to" inhibitor over a broad range of conditions. Simulated test conditions varied from easy-to-treat low-concentration ratio HVAC towers, to water reuse applications, and into the range of hydrofracturing flowback brines. Data developed and reported includes inhibitor minimum effective dosage requirement as a function of saturation ratio (scaling index), temperature as it affects rate, residence time, and PBTC dissociation state. Performance as the sole inhibitor, and when applied with commonly used polymers, is also discussed. This article stresses the upper limits for the inhibitor when used as the sole treatment, and in combination with other inhibitors. Both synergism and antagonism were observed for the inhibitor blends, with the interaction type being a function of ratio. Future reports will expand the PBTC performance database to include calcium sulfate and barium sulfate scale control.
Introduction PBTC Models for Minimum Effective Dosage Existing models for calculating the minimum effective dosage for scale control have been applied to industrial and oil field scale control treatment optimization since the 1970s. Standard correlations are routinely used in developing the models.1,2,3,4,5,6,7,8,9,10 The models typically 49
apply to a single inhibitor. There is a driving force limit for each inhibitor, above which scale control cannot be achieved, regardless of the inhibitor dosage. Knowing the upper limit is critical for selecting the optimum treatment program and in specifying control limits for a system such as an open recirculating cooling tower or membrane system. Limits for individual inhibitors have been well documented. Studies have been conducted to determine the impact of blending inhibitors on the upper driving force limit. Upper driving force limits, as expressed by calcite saturation ratio, were measured for calcium carbonate inhibition by individual inhibitors and combinations. Results were evaluated, and blends were found to do one of the following: Increase the upper limit above that of either inhibitor when applied alone (synergism). Decrease the upper limit (antagonism or competitive inhibition). Provide an upper limit in between that of the individual inhibitors (equivalent efficacy). Test methods, data, and correlations are presented and discussed with respect to mechanisms.
How Inhibitors Work When reactants are mixed, a solution is heated or cooled, undergoes a pressure change, or is otherwise perturbed, but the impact of the environmental changes is not immediate. A finite time passes before the perturbation affects any susceptible reaction. In the case of scale formation, induction time can be defined as the time before a measurable phase change (precipitation or growth) occurs after perturbation.4,7 In a pure system, with only the reactants present, such as calcium and carbonate or barium and sulfate, scale formation might proceed as follows: 1) Aqueous calcium carbonate molecules congregate and form larger and larger clusters. 2) The clusters grow to a critical size and overcome the "activation energy" needed for the change from the "aqueous" to "solid" phase to occur. 3) The phase change is then observed. In the case of CaCO3, pH drops as the salt changes phase, and the induction time can be defined. 4) Crystals will then grow. the Analyst Volume 25 Number 3
PBTC Revisited continued
Scale inhibitors do not prevent scale. They delay the inevitable. The minimum effective dose for a given water will prevent scale formation, or growth, until the water has passed through the system. The time until scale formation or growth is initiated is termed induction time. Scale inhibitors are induction time extenders. Untreated, there is a baseline induction time before scale growth occurs (Tinduction 0). This baseline induction time decreases as the driving force for scale formation increases. So, induction time decreases as scale driving force, like saturation ratio, increases. A driving force index is integral to modeling induction time. All of the indices in use for driving forces, including the simplest and the most sophisticated, are derived from the basic relationship, which defines the solubility product. For calcium carbonate this equates to:
Equation 4) Tinduction 0 = 1
Equation 1) {Ca 2+}{CO32-} = Ksp
where {Ca 2+} is the calcium activity in the water at the current conditions
inhibitor is the scale inhibitor molar concentration
M is s coefficient related to the number of molecules in a critical cluster
N is s coefficient
k is a temperature dependent rate constant
Saturation is the saturation ratio defined in Equations 2 and 3 and Table 1.
{CO3} the carbonate activity at current conditions Ksp is the solubility product at the current conditions of temperature, ionic strength, and pressure. The "free" ion activities for {Ca 2+} and {CO32-} are used in ion association models to improve accuracy and account for phenomena such as common ion effects. A simple arrangement of Equation 1 relates "what we have" to "what we can ultimately have": Equation 2) Saturation Ratio = {Ca 2+}{CO32-} what we have Ksp
what will be at t = â&#x2C6;&#x17E;
Equation 2 can be generalized to cover any commonly encountered scales: Equation 3) Saturation Ratio =
{IAP} what we have
K'sp
what will be at t = â&#x2C6;&#x17E;
where {IAP} is the ion activity product for the scale being evaluated, and K'sp is the solubility product for the scale forming specie under the conditions being evaluated. 50
k [x Saturation] M
Inhibitors extend this time by interfering with one of the steps in scale formation or growth (Textended) Equation 5) Textended
=
[inhibitor] N k [x Saturation] M
where Tinduction 0 is the induction time untreated Textended is the induction time when treated
Induction time has been studied extensively for industrial processes. Original crystallization studies were conducted to maximize production. In the case of sucrose crystallization, the objective is to minimize induction time and maximize crystallization. In the case of scale control, the objective is to extend the induction time until a water has safely passed through the cooling system, or other process adversely affected by scale. The induction time, in the absence of scale inhibitors, has been modeled for common scales, including barite (BaSO4) and calcite (CaCO3).4 Figure 1 profiles the untreated induction time for calcite in the practical operational range for calcite of 0 to 150x saturation. This range was chosen because it is the effective range for most scale inhibitors. The 150x saturation-level limit is a commonly accepted upper limit for operation with common inhibitors such as phosphonates and polymers. PBTC has been used successfully the Analyst Volume 25 Number 3
PBTC Revisited continued
at operational systems with observed calcite saturation ratios in excess of 200. It should be noted that the induction times for both calcite and barite are several orders of magnitude below the typical residence time in an open recirculating cooling water system, oil field production process, or membrane system. As a result, the use of the thermodynamic saturation ratios for predicting scale is accurate and an acceptable practice in typical operating ranges for these systems. Actual induction times in practical operating systems will typically be lower than those of a pure system. Existing "seed" crystals and deposits provide a substrate for crystal growth without the necessity for achieving the "activation energy" for the initial phase change. In other words, it is easier to keep a clean system clean than to keep a dirty system from getting dirtier. Other factors can also decrease induction time. Ideally, studies will incorporate both “seeded” and “unseeded” conditions. It is imperative that the upper driving force limits for inhibitors be known so that dosage curves and inhibitors are not applied to waters above the point where no dosage of the inhibitor will be effective.
Growth on Existing Substrates At low saturation ratios, below the critical saturation ratio where seed crystal formation occurs, precipitation occurs by growth at active sites on an existing substrate. For precipitation from a pure solution, the substrate would be the scale of interest. In an operating practical environment such as oil field production, an industrial cooling system, or a reverse osmosis unit, the substrate could be any surface where growth might occur. Seed Crystal Formation and Growth Above the critical saturation ratio, spontaneous nucleation can occur, followed by growth on the seed crystals. As the degree of supersaturation increases, the rate of seed crystal formation increases. Minimum Effective Dosage Profiles Minimum effective dosages are compared for the common phosphonates ATMP (aminotris(methylenephosphonic acid), HEDP (1,1-hydroxyethylidene diphosphonic acid), and PBTC to demonstrate the application 52
niche for the various approaches. Figure 2 compares the induction time extension response to dosage. Figure 3 simulates the dosage response to increasing stress as saturation ratio and temperature increase. Table 2 outlines the conditions modeled for the response to increasing stress in Figures 5 and 6. Inhibitors and their blends have specific application niches where they tend to be used. As seen in Table 5 and Figure 3, application niches for the phosphonates compared can be identified based upon performance and mg/L dosage as follows: HEDP tends to provide the lowest dosages at lower saturation ratios and lower temperatures. ATMP tends to control scale at lower dosages at intermediate saturation ratios and temperatures. Of the three phosphonates compared, PBTC tends to provide the lowest dosage and highest upper limit at high saturation ratios and temperatures.
The "Comfort Zone" The "comfort zone" is defined as a region where achieving scale and corrosion control is a relatively stress-free operation. Calcium carbonate scale potential is well below the accepted limits for common phosphonates (calcite x saturation 30 to 80, versus a limit of 135 to 140 x saturation). Temperatures are below 120 °F. HEDP tends to be used with polymers and copolymers in the "comfort zone." The "Typical Industrial Range" The "typical industrial range" is defined as a region where achieving scale control is well below the normal inhibitor upper limit of 150 x saturation (60 to 120 x saturation), with increased temperature stress. The "Stressed CaCO3 Zone" The "stressed CaCO3 zone" is defined as a region where achieving scale and corrosion control is difficult and requires excellent control. Calcium carbonate scale potential is approaching or above the accepted limits for common phosphonates (calcite x saturation 120 to 200 versus a standard treatment limit of 135 to 140 x saturation). Stress-tolerant inhibitors such as PBTC and blends of PBTC with PMA (polymaleic anhydride) are the Analyst Volume 25 Number 3
PBTC Revisited continued
required. Blends of HEDP and PMA are sometimes used. The stressed zone is typically the niche for the PBTC PMA blend.
Experimental Procedure The Behavior of Inhibitor Blends—Saturation Ratio Limit Inhibitors have an upper driving force that they can handle. Once this upper limit is reached, even drastically increasing inhibitor dosage will not provide scale control. Inhibitors included in this study are outlined in Table 2. Typical upper limits for single inhibitors are outlined in Table 4. Note that the upper limit for common inhibitors is around a calcite saturation ratio of about 150 x, while the upper limit for PBTC is over 200 x when applied as the sole inhibitor. It has been known that blending inhibitors can increase the upper limit. The combination of a phosphonate and PMA, for example, has been observed to raise the upper limit well above that of the phosphonate alone. Not all combinations or ratios show this positive effect. Possibilities for the impact of inhibitor blends on the upper limit include: The limit for the blend would be the lower of the limits for the inhibitors in the blend. The limit would be a weighted average of the limit for each inhibitor when applied alone. The limit would be the higher of the limits for the individual inhibitors in the blend. The new limit would be higher than the limit for any of the inhibitors in the blend. A laboratory study reproduced the impact of polymaleates observed in field applications when blended with PBTC and for the phosphonate blend of HEDP and ATMP. The study measured the upper saturation ratio limit for calcium carbonate for the individual inhibitors, and when blended in various ratios. Two solutions were prepared: An anion solution of bicarbonate and carbonate. A cation solution of calcium.
The test is initiated by mixing the cation and anion solutions. pH is monitored as anion solution and added to the mixture. The additional anion solution increases carbonate, pH, and the calcium carbonate saturation ratio. The upper limit for the inhibitor is indicated by loss of control and a drop in pH as calcium carbonate precipitates. The solution is also observed for turbidity. Figure 4 profiles a typical plot of pH as the solution is “titrated” to the upper saturation limit for the inhibitor. Care must be taken in the experimental design so that the solubility of inhibitor salts does not interfere, such as through the formation of Ca-HEDP. The time for the test must also be less than the treated induction time to prevent precipitation other than that from exceeding the upper limit. The PBTC:PMA combination was studied and compared to other common inhibitor combinations in search of synergy and antagonism.
Results
PBTC:PMA Combination: The combination of PBTC and PMA demonstrated the most dramatic impact of blending on the upper saturation limit, as depicted in Figure 5. As the blend ratio in the test goes from polymer only to phosphonate only, there appears to be a drop in the upper limit at high polymer to PBTC ratios, possibly indicating an antagonistic effect when the polymer is the primary inhibitor. The upper limit failure point increases to a maximum at a ratio of 3:1 PBTC to polymer, with the upper limit of the higher ratios indicating a synergy between the PBTC and lower levels of PMA. This trend has been observed in field applications. Antagonism might occur as a result of polymer adsorbing near newly formed active sites and blocking the PBTC from nearby active sites, or by changing the surface charge to decrease attraction. In this case, the upper limit for the blend would be expected to have a lower limit than either inhibitor alone. Synergy might occur as a result of polymer attaching near newly formed active sites and by changing the surface charge to increase the attraction of PBTC to nearby active sites. In this case, the upper limit for the blend would be expected to have a higher limit than either inhibitor alone.
The scale inhibitor or blend being tested is included in the anion solution. No inhibitor is added for the blank untreated tests. 54
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PBTC Revisited continued
HEDP:PMA Combination: The combination of HEDP and PMA demonstrated a similar impact trend to the PBTC:PMA blend on the upper saturation limit, as depicted in Figure 6. As the blend ratio in the test goes from polymer only to phosphonate only, there appears to be a drop in the upper limit at high polymer to HEDP ratios, possibly indicating an antagonistic effect when the polymer is the primary inhibitor. The upper limit failure point increases to a maximum at a ratio of 3:1 HEDP to polymer, with the upper limit of the higher ratios indicating a synergy between the HEDP and lower levels of PMA. The overall impact of blending the phosphonate HEDP with PMA upon the upper saturation limit appears to be less than the PBTC:PMA blend. HEDP:ATMP Combination: The combination of ATMP and HEDP demonstrated a positive impact on the upper saturation limit, as depicted in Figure 7. As the blend ratio in the test goes from HEDP only to ATMP only, the upper limit failure point increases to a maximum at a ratio of approximately 1:1 HEDP to ATMP, with the upper limit indicating a synergy between the HEDP and ATMP at all ratios. A similar trend in inhibitor effectiveness was observed in similar studies that demonstrated an increase in percent inhibition for phosphonate blends.9
The Behavior of Inhibitor Blends—Inhibitor Solubility As mentioned as a caveat for test protocols, inhibitor upper limit tests should be conducted in a range where the solubility of the inhibitor will not decrease the limit measured. The formation of salts such as a CalciumInhibitor or Iron-Inhibitor have been known to limit the maximum dosage in a water. Incorporation of co- and higher polymers into a blended inhibitor formulation allows the product to function at higher dosages and has been observed to prevent deposition or inhibitor activation of inhibitor salt solubility limited treatments. A reduction in dosage is not necessarily observed. The added protective polymer allows the original scale inhibitors(s) to function at a higher dosage—a dosage above their normal solubility. Some might term this “synergy.” Others may call it “smart formulating.” In either or both cases, the end result is that the addition of another molecule into the formula allows the inhibitors to function at 55
a higher dosage under the same conditions. Inhibitor salts can be modeled like any scale. Their solubility, and the inhibitor dosage required to prevent their precipitation or deactivation, can be modeled using the same methods used for mineral scale inhibitors. The degree of supersaturation for the Metal-Inhibitor reactant is calculated. Studies can be run to determine the impact of copolymer dosage on Metal-Inhibitor induction time and degree of saturation.
Conclusions
PBTC earned its place as the “go-to” inhibitor for stressed applications due to its high calcium tolerance and expanded upper limit for calcite scale potential. Many formulators observed that blending inhibitors, such as PBTC and polymaleates, raised the maximum driving force limit at which the inhibitor is effective, and demonstrated synergy. Field experience and laboratory studies optimized blend ratios. Optimizing the ratio of the inhibitors PBTC and PMA was essential for operation in the region of synergy rather than at ratios resulting in antagonism and a decreased upper limit. It is the author’s opinion that combinations further enhanced and solidified the use of PBTC in high-stress applications.
Further Work
Additional inhibitors and blends will be studied using the procedure outlined for measuring the upper saturation ratio limit. The impact of inhibitor blends upon induction time extension will be studied for inhibitors with existing models (Table 4) and blends until the standard arsenal of phosphonates and proprietary inhibitors has been studied, including phosphonates in combination with higher “designer” polymers. Studies for both upper limit and induction time extension will be run in both a “clean” system and when “seeded” with the solid phase of the scale under study. Scales studied will be expanded to include CaCO3, CaSO4*2H 2O, BaSO4, and where appropriate, Ca:PO4. As data is available, the laboratory results and trends will be validated to operating industrial systems.
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PBTC Revisited continued
Figure 1. Untreated Induction Time vs. Calcite Saturation Level
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PBTC Revisited continued
Figure 2. Phosphonate Dosage vs. Calcite Saturation Ratio (at constant temperature and induction time)
Figure 3. Minimum Effective Dosages for the Phosphonates ATMP, HEDP, and PBTC
Figure 4. Example of Progressive Carbonate Test Plot
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PBTC Revisited continued
Figure 5. Impact of Polymer to Phosphonate Ratio Upon Maximum Saturation for Enhanced PMA and PBTC
References
1. R.H. Ashcraft, "Scale Control Under Harsh Conditions Using 2-phosphonobutane 1,2,4- triccaroxylic acid PBTC," NACE Corrosion '85, Paper 123, 1985 2. R.J. Ferguson, “Developing Scale Inhibitor Models”, WATERTECH, Houston, TX, 1992.
3. R.J. Ferguson, D.A. Weintritt, “Developing Scale Inhibitor Models For Oil Field”, NACE, CORROSION 1994, Baltimore, MD.
4. R.J. Ferguson, B. R. Ferguson, and R. F. Stancavage, “Modeling Scale Formation and Optimizing Scale Inhibitor Dosages in Membrane Systems”, AWWA Membrane Technology Conference March 30, 2011 Long Beach, CA, USA
5. M.B. Tomson, G. Fu, M.A. Watson, and A.T. Kan, "Mechanisms of Mineral Scale Inhibition, Society of Petroleum Engineers, Oilfield Scale Symposium, Aberdeen, UK, 2002.
6. B.W. Ferguson, R.J. Ferguson," Sidestream Evaluation of Fouling Factors in a Utility Surface Condenser," Journal of the Cooling Tower Institute, 2, (1981):p. 31-39.
Figure 6. Impact of Polymer to Phosphonate Ratio on Maximum Saturation for Enhanced PMA and HEDP
7. R.J. Ferguson, O. Codina, W. Rule, R. Baebel, Real Time Control Of Scale Inhibitor Feed Rate, International Water Conference, 49th Annual Meeting, Pittsburgh, PA, IWC-88-57. 8. R.J. Ferguson, “30 Years of Ultra Low Dosage Scale Control”, NACE, CORROSION 2003, San Diego, California
9. R.J. Ferguson,” The Kinetics Of Cooling Water Scale Formation And Control,” Association of Water Technologies Annual Meeting, Association of Water Technologies Annual Meeting, September 14 - 17, 2011 Atlanta, GA, USA
10. D. Vanderpool, Calculating Minimum Threshold Inhbiitor Dosage, The Analyst, XII (3), Asociation of Water Technologies, 2000.
11. R.J. Ferguson, Computerized Ion Association Model Profiles Complete Range of Cooling System parameters, International Water Conference, 52nd Annual Meeting, Pittsburgh, PA, IWC-91-47.
Figure 7. Impact of Phosphonate Ratio on Maximum Saturation for ATMP and HEDP
12. R.J. Ferguson, A.J. Freedman, G. Fowler, A.J. Kulik, J. Robson, D.J. Weintritt,” The Practical Application of Ion Association Model Saturation Level Indices To Commercial Water Treatment Problem Solving,” (Washington, DC: American Chemical Society Annual Meeting, Division of Colloid and Surface Chemistry Symposia, Scale Formation and Inhibition, 1994). 13. R.J. Ferguson, A Kinetic Model for Calcium Carbonate Scale, CORROSION/84,Paper No. 46, (Houston, TX:NACE INTERNATIONAL 1984).
14. R.J. Ferguson, “The Impact of Inhibitor Speciation on Efficacy: pH, Ionic Strength and Temperature Impact,” Presented at the 2015 Cooling Technology Institute Annual Conference, New Orleans, Louisiana February 9-12, 2015 15. D.W. Griffiths, Roberts, S.D., and Y.T. Liu, ”Inhibition of Calcium Sulfate Dihydrate Crystal Growth by Phosphonic Acids – Influence of Inhibitor Structure and Solution pH,” Society of Petroleum Engineers, International Symposium on Oil Field and Geothermal Chemistry (1979).
Reproduced with permission from NACE International, Houston, Texas. All rights reserved. Author(s), Paper 9105 presented at CORROSION/2017, New Orleans, Louisiana. © NACE International 2017.
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Membership Benefits
Integrated cash rewards and incentives for lifestyle improvement.
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Association News
This month, AWT will be transitioning its listserv from its existing software platform to a new and improved community platform: the AWT Exchange (http:// exchange.awt.org). Here’s a quick overview of some of the new features you can expect in the AWT Exchange: Enhanced discussion capabilities. Now you’ll receive emails that are more structured and easier to read than a traditional listserv or forum alert. Improved Member Directory search. You can find members by name, location, area of expertise, work setting, and more. Granular privacy controls. You can have complete control over what information you share with members of the community and your contacts.
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Centralized subscription management. You can manage your subscriptions to all discussions in one place. Choose to receive daily digests or real-time emails by group. Resource sharing. All attachments posted to discussions are archived in a dedicated Resource Library. You can also add documents to share anytime you want. Need some advice or want to compare notes with your peers? Visit the AWT members-only Exchange community to engage your fellow members in an informative discussion.
the Analyst Volume 25 Number 3
Industry Notes Advantage Controls and “Green” Energy
Advantage Controls, a worldwide provider of industrial water treatment equipment for boilers and cooling towers, has expanded its Steel Fabrication Division. The new expansion is to an existing building adjacent to the headquarters and will possess just under 1,000 solar panels covering 22,000 sq ft. of its rooftop. The $3.5 million expansion for Advantage TerraFab includes the solar panels, increasing overall building footprint to 65,000 sq. ft; state-of-the-art powder coat and liquid paint coating systems; and energy-efficient LED lighting. Advantage plans to continue this process to make all facilities as environmentally friendly as practical.
H2O Advantage TerraFab is a steel manufacturer and fabricator and is AISC certified in providing high-quality structural steel buildings (commercial/industrial), simple bridge and components, and sophisticated coatings, as well as OEM products, including Truck Lungs©. For more information, visit www.advantagecontrols.com.
H2SO4
The photovoltaic system will supply up to 1,500 kWh daily, nearly 70% of the total energy required to maintain welding production. The system is large enough to power over 40 residential homes per month, which results in massive savings during peak hours. The project will pay for itself within six or seven years. Morris says, “Solar panels make sense with the ever-increasing costs and demands of electricity.” He has met with many agencies, state politicians, and local business leaders to make Muskogee unique by pushing for alternative energy throughout the city. Morris continued, “It’s our way of helping the community to increase its total available power for new business growth within the community.” Advantage TerraFab will be the first steel fabrication company in Oklahoma to install solar panels for its production needs—a great benefit for Muskogee residents as well as their team members. Advantage TerraFab will also measure its current building efficiency through the Leadership in Energy and Environmental Design (LEED) program. The company’s goal is to achieve a “Certified” rating by 2020, focusing on the building carbon footprint among air quality, renewable energy, energy savings, and water efficiency. “By eliminating certain wastes, not only do we become more efficient in getting a return on our dollar, but more importantly, it empowers our team,” said Morris.
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Design Water Treatment Systems in an Even More User-Friendly Process
The specialty chemicals corporation LANXESS has made further enhancements to its LewaPlus software for designing water treatment systems. With this 2.0 release, users now have the unique ability to combine per drag and drop different technologies in one design. “Because modules can be added to a project via drag and drop, LewaPlus 2.0 is now even more intuitive to use than existing programs on the market,” emphasizes Dr. Jens Lipnizki, head of technical marketing membranes at LANXESS. Now, users can seamlessly simulate complex plant designs including a combination of several treatment steps in a single design process. The water analysis calculated by the individual modules is automatically taken over as feed to the subsequent module. During the design process, the user can change the design of the system via drag and drop.
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Industry Notes continued
“With LewaPlus 2.0, calculations can be made for designs that not only treat the purified stream of water but also the so-called retentate. As a result, environmentally friendly overall concepts can be calculated in order to significantly reduce the volume of wastewater produced in practice,” Lipnizki added. The modules can be added to a project via drag and drop—even retrospectively in a later stage of the process. This is helpful if the system designer decides to add pretreatment of feed during the design process, for example. Compared to previous versions, the software can now show all of the selected modules in a combined PDF report. A list of links to the respective modules, which can be individually renamed, helps the user to navigate through the PDF quickly and easily. In addition, the new version also offers a product finder. It enables LewaPlus users to identify which Lewatit and Lewabrane quality products they can use instead of conventional ion exchange resin types and reverse osmosis membrane elements to upgrade their plants. The intuitive design software LewaPlus is a comprehensive tool for planning and designing an industrial water treatment system and allows the dimensioning of ion exchange and reverse osmosis systems for a for a wide variety of unique system configurations, including several one-of-a-kind process configurations that can only be achieved with Lewatit and Lewabrane product technology. Numerous modules are available for the calculation of every step of the water treatment process. As a result, users can precisely plan important factors such as operating costs, power consumption, and water quality. One module can even be used to model a CCRO system (closed circuit reverse osmosis). This helps to enhance the ecobalance of water treatment through the use of either ZLD (zero liquid discharge) or MLD (minimal liquid discharge) treatment processes.
H2O Innovation: Piedmont Obtains Its ISO 9001: 2015 Certification and Positions Itself Strategically on the International Desalination Market
H2O Innovation Inc. is proud to announce that it recently obtained its ISO 9001:2015 certification, ensuring quality management, from design to manufacturing, of all its products and components for water treatment systems. This is a major milestone in its strategic positioning with the major players of the desalination industry. By 2025, the international desalination market is expected to reach $27 billion, representing a 103% increase compared to 2016, mainly driven by rapid industrialization, population growth, and depletion of freshwater bodies. The Middle East and Africa are the largest markets and are expected to maintain that dominance over the coming years due to the high supply-demand gap of potable water (Source: Hexa Research Report, 2017). “We are proud to have obtained, in a very short amount of time, the ISO 9001: 2015 certification. This certification is part of a positioning approach on the international desalination market that will certainly allow us to adequately meet the needs of our large customer base. We believe this addition will have a direct impact on increasing our sales and our customers' trust in our product lines. It is also a prerequisite for most large EPC (Engineering – Procurement – Construction) involved in the manufacturing of large desalination plants,” stated Ties Venema, commercial director of Piedmont. Piedmont initially started offering a first line of flexible coupling products and then launched its line of cartridge filters housings made of reinforced fiberglass (FRP) two years ago. In fact, the Piedmont team is currently working on developing a third line of products that should be ready in the coming months. For more information, visit www.piedmontpacific.com.
Extensive information about LANXESS water treatment products and services can be found at http://lpt. lanxess.com/. The LewaPlus design software can be downloaded at no charge. 62
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Industry Notes continued
The Nexus Between Mechanical Filtration and Chemical Treatment in Cooling Water Applications
Selecting the right filtration technology for all applications becomes easy when you perform a particle distribution analysis (PDA). Laser counters are most commonly used and are accurate and affordable solutions.
Considerations must be given to determine if the total suspended solids (TSS) illustrate a majority of total counts less than 10.0 microns. The microscopic particles between 0.45 and 5.0 microns are responsible for biofilm buildup and increased energy and operational costs. Synergies through combined treatment technologies allow for: Enhanced filtration and chemical treatment programs in a sustainable manner. Cleaner heat exchange surfaces that reduce or maintain design performance criteria. Savings in energy, water, labor, and downtime. Reduced erosion of piping, valves, seals, and impellers. Better cooling water heat rejection. Reduced MIC, anaerobic and harboring of higher life forms. Less frictional drag of pumped water caused by biofilm. Biofilm has a thermal conductivity of just 0.6 and is four times as resistant to heat transfer as compared to calcium carbonate scale. Years of research have proven that biofilm starts with TSS around a 5.0-micron size range, with smaller particles attached to the base layer later on. Selecting the right technology that can reduce TSS between 0.45–5.0 microns is of the utmost importance.
Michael J. Highum, CPCU, Becomes a Partner at McGowan Insurance Group
Effective the end of last year, Mike Highum became a partner at McGowan Insurance Group. Since he joined the agency in 2003, Mike has been an integral part of its growth and success. The many roles he has performed at the agency have given him unique perspectives of both the company’s strengths and opportunities for improvement. Most importantly, he has been a consistent driver toward McGowen’s organic growth that has continually outperformed industry norms.
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Well before it became an industry trend, Mike’s vision and persistence positioned McGowan as an expert in multiple niche industry segments. The Agency winning the 2017 Supplier of the Year from AWT is one of many examples. Mike’s opportunity to become an agency principal is further evidence of McGowen’s commitment to the same core values that have guided it for almost 90 years: family owned, committed to community and our industry, and being a resource first. At McGowan, we are passionate about our potential and believe that everyone should have the tools to reach theirs. Mike’s leadership will continue to help the agency build relationships that are sustainable and serve our client’s best interest.
ResinTech Hires Arna Ramic
Arna Ramic has joined ResinTech as an ion exchange technologist working out of the company headquarters in West Berlin, New Jersey. Previously an engineer for Environmental Resources Management's air quality team, Arna’s technical consulting background in the oil & gas, power, and energy industries bolsters ResinTech's already rich experience in the power sector. She has authored several case studies and white papers on topics that include "Evaluation of Dechlorinating Chemicals for Spent Membrane Cleaning Solutions" and “Removal of Technetium-99 on I-X Resin.” A native of Bosnia, Arna moved to the United States at age 5 and eventually earned a B.S. in chemical engineering from the University of Washington in Seattle. She will be reporting to ResinTech's technical director, Peter Meyers, and president, Larry Gottlieb. For more information, visit www.resintech.com.
ProMinent Fluid Controls Announces New Expansion of U.S. Headquarters
ProMinent Fluid Controls, a global manufacturer of highquality chemical metering pumps and industrial water treatment equipment, has more than doubled the size of its U.S. headquarters in Pittsburgh, Pennsylvania, over the past four years. It expanded its square footage from 46,000 sq. ft. to 66,000 sq. ft. in 2014 with a new building to increase engineering and chemical feed system production. Just two years later, a 35,000 sq. ft addition was needed to accommodate the fast-paced growth, increasing the Analyst Volume 25 Number 3
Industry Notes continued
the entire facility to over 100,000 square feet. The latest expansion includes a weld shop, state-of-the-art training facility, and more office space. Investing in several new Kardex inventory systems has allowed the company to continue shipping pumps and controllers to its customers within one to three days. ProMinent Fluid Controls has been manufacturing chemical feed pumps, controllers, and chemical feed and monitoring systems in the United States since 1978. ProMinent, an ISO 9001 registered facility that includes a UL 508A electrical department, has grown to be a leader in the engineering and manufacturing of quality chemical feed components and systems. Please call (412) 787-2484 or go to www.prominent.us to learn more.
displayed strong sales and operational leadership and oversaw a period of rapid growth, highlighted by the expansion of Sterilex’s brand and portfolio of award-winning products for microbial control and detection. Concurrent to Alex’s appointment, Dr. Shira Kramer, Sterilex’s founder, will remain as CEO and chairwoman. As founder and past president, Shira led the business and was instrumental in strategic leadership, obtaining key regulatory claims, new product innovation, and commercialization. In addition, she led the sustained growth of many key markets and has played an important role in establishing the brand as it is today. “Alex’s efforts can be directly seen in the results,” said Shira. “With his leadership, ability to deliver results, and strategic thinking, Alex is the ideal candidate to execute Sterilex’s strategic key business initiatives and drive sustainable growth,” she stated. To learn more, visit www. sterilex.com.
APTech Breaks Ground at Manufacturing and Corporate Headquarters
Sterilex Appoints New President
Sterilex announces the promotion of Alex Josowitz to the position of president. As president, Alex will have responsibility for the organization’s operational functions and will play a key role in the company’s strategic direction.
“
I am excited and honored to take on this new role and look forward to working with our talented and growing team to continue to drive innovation, sustain growth, and develop value-added products for our customers,” said Alex.
Alex has worked at Sterilex for 12 years, taking on a variety of sales, marketing, and operational leadership roles. Most recently, he served as executive vice president of business development and operations, where he
APTech Group, Inc. broke ground at the site of its new manufacturing and corporate headquarters located in West Chester, Ohio, on June 29. The expanded facility, which is set on 7 acres, will allow for its office and production of chemicals and equipment to be housed in the same complex. As a global manufacturing leader of safe and sustainable solid-concentrated water treatment products, APTech has experienced tremendous growth throughout the past 15 years and is looking forward to operational optimization of the additional space that this facility will provide, along withopportunities for further expansion.
The groundbreaking was well attended by many community and county officials, affiliated contractors, and architects as well as APTech employees and their families. James Heimert, CEO of APTech, states “this is a new chapter in APTech’s history—we are doubling our size, relocating everything, and foresee growth.” APTech’s managing director, Matt Horine, states “the added capacity and flexibility will allow us to strengthen our position as a supplier to the water treatment market.” Anticipated completion date of the facility is December 31, 2018. For more information, visit www.aptechgroup.com. Continued on p. 67
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Making a Splash
Marta Drewniak, Ph.D.
Chem-Aqua, Inc. Irving, Texas
What prompted you to start volunteering with AWT?
Few years ago, when I joined the water treatment R&D group at NCH Corp., I changed my carrier from polyolefin compounds and structural foams to water treatment. I had to learn a lot since I was new to water treatment, and one of my biggest challenges was to get to know people in industry. I have attended some AWT conferences in the past, but last year I finally had a chance to enjoy the whole AWT conference in Grand Rapids. I got introduced to many people during those couple of days, but I still needed to further expand my network. This is when I realized that the best opportunity to get to know people in water treatment and gain experience is to volunteer on one of the AWT technical committees. My NCH co-workers introduced me to the Cooling Subcommittee, and I decided to spend some helping out. For the last few years I have been benefitting from othersâ&#x20AC;&#x2122; work, utilizing various AWT resources, such as tutorials, webinars, and technical papers, so it was my turn to at least try to give back something to this group. I had also noticed that there were not too many females in water treatment, so I thought that by volunteering, I may be able to contribute to better representation of female voices in this industry.
What has been the most rewarding thing about volunteering?
I have only been on the Cooling Subcommittee for few months. Right from the start, I was welcomed by other members, and even though I did not have a long history of experience in water treatment, I was encouraged to participate in the projects; that by itself was very encouraging. I think that seeing the completed poster from the first project I got involved with will be very rewarding.
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Why would you encourage others to become a volunteer?
Initially, I was not sure whether there would be enough work for all volunteers who joined the technical committee after the last conference, but I was wrong, and I would definitely encourage others to volunteer. There is always something that needs to be done, and the more people volunteer, the easier it is on everyone; we all have very busy schedules. AWT needs multiple voices and opinions from various water treatment professionals, new and experienced, so it can represent the entire water treatment community and provide benefits to all.
Tell us about a current project you or your committee is working on.
The goal of the first project I got involved in is to update the poster with â&#x20AC;&#x153;Guidelines for Corrosion Rates.â&#x20AC;? AWT issued a poster with classification and placement of corrosion coupons for Open Recirculating Cooling Water Systems in 2010. The information on the poster needed to be updated to match the newest industry recommendation. When this project was proposed to the committee, I immediately thought that I should get involved. Not only did it seem to be fairly short and easy for a first project, but it also complemented my current work, where I was investigating aluminum corrosion and protection. The project is almost complete; the appropriate information was gathered, and we are waiting for editors to update the poster.
the Analyst Volume 25 Number 3
Making a Splash continued
Industry Notes continued
How have you been able to utilize the expanded business connections you’ve made while volunteering?
Introduction of 316 Stainless Steel Metallic Sealless Pumps
There are two projects that come to mind with regard to impacting AWT and its members. The foldout coupon poster still comes to mind as a highlight for the Marketing/Communications Committee. The team was able to take technical information and create a solid technical resource for AWT members. The Marketing/ Communications Committee also assisted in creating ads for the IFMA Journal, bringing water treatment awareness to facility managers and the industry at large.
How have you been able to utilize the expanded business connections you’ve made while volunteering?
Known for over 60 years of manufacturing innovative nonmetallic sealless pumps, Iwaki America is pleased to announce the introduction of its 316 stainless steel metallic sealless pump line. Iwaki Sanwa will feature two series of pumps; the MP series will feature flows to 340 gallons per minute while the smaller MMP series will be a fractional horsepower series of pumps with flows to 24 gallons per minute. Both series incorporate 316 stainless steel construction, a one-piece nonwelded rear casing, and silicon carbide “D” bearings, allowing for limited dry run operation. For more information, visit www.iwakiamerica.com.
With only a very short time on the Cooling Subcommittee, I have not yet been able to fully utilize my new business connections, but I am looking forward to expanding my network.
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the Analyst Volume 25 Number 3
Charity Update
Windshield Time— Honduras Style
Highlights from an AWT member’s trip to Honduras with our charity partner, Pure Water for the World. By Rye Thompson, Innovative Water Consulting
“Toyota Hilux trucks work darn hard on rural Central American dirt roads!” “Windshield time” took on a whole new meaning last week, as I found myself standing in flatbeds, in the open air, riding with the Pure Water for the World (PWW) staff and volunteers from across the United States in rural Honduras. We were making “service calls”… installing biosand water filters in rural, dispersed family homes. It was amazing work. We AWT members are incredibly lucky to be aligned with a charity like PWW. I spent last week with them in Honduras. They are the real deal. Here are some quick notes…before I get back to my day job of running a business! PWW is AWT’s charity partner. We see them at the AWT conferences. I finally pulled the trigger and joined them on a weeklong volunteer trip to Honduras…and I am so glad I did. Last week, we installed 35 biosand water filters in homes, which now provide 210 people with clean, filtered water for drinking and bathing. These families do not have running water or electricity. They use 5-gallon buckets to bring water into their homes! We completed the building of four latrines, complete with sinks (hand-washing stations), at two rural community schools. Folks: prior to last week, these school kids had no place to wash their hands after doing what we all do everyday when we visit a bathroom. No wonder they get sick a lot! We distributed 200 hygiene kits to families and helped the PWW staff and local doctor administer over 350 deworming pills. Yeah, people here have worms living in their intestines that they get from drinking and bathing in contaminated water. The PWW folks do water work with a purpose! Evenings were spent eating great food and sharing camaraderie and adult beverages with the volunteers. 68
We visited an amazing cigar factory and bought boxes of excellent, award-winning cigars at low, low prices. Load up! I was so impressed with how lean PWW runs. My business partner and I are pledging our 2018 charity funds to this organization, as we have personally vetted them and their work. Volunteering with PWW in Honduras is a very unique experience for AWT members to combine a week of adventure and travel with a purpose and charity. The PWW team is top notch and was at our sides the entire time while we were in their country. Our company’s employees will be joining in on future trips for sure! Maybe we’ll see you there, too!
the Analyst Volume 25 Number 3
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CWT Spotlight
missed by anyone considering certification today. My background included lots of math and science, so the calculations came easy. Reviewing basic math and chemistry will really help.
Vince Resor, CWT
Chardon Laboratories, Inc. Reynoldsburg, Ohio
What prompted you to obtain your CWT, and when did you begin the process by taking the exam? The CWT program was new when I took the exam at the Broadmoor in Colorado Springs at the 1996 convention. I was looking for more after I worked my way through my company's training resources, and the new CWT program was the highest level of training and certification I could find. I began studying several months before the convention. At the time, the CWT Manual was a collection of papers by a diverse array of authors and loosely bound into a manual. Excellent reading though. What advice would you give those thinking about taking the exam? A few of our people look at taking the CWT exam every year, and my advice has been the same for years. Get the manual and attend the training sessions prior to the exam date. It's by far the best preparation, and I wish it had been around when I took the exam. What was the most difficult aspect of the exam? As I recall, it was several hundred questions spanning seven straight hours of testing. Time may have embellished those numbers, but it was a long test. Staying focused, that took energy. How did you prepare for the exam? I used the first generation of the CWT Manual. Today's version flows far better and is a world-class manual. The classes were not available back then but should not be
Why do you feel this credential was important to have? At the time, I was directing our company training program, and completing our highest level was an important example for others entering or working their way through the program. As the CWT program has gained momentum, I get more and more questions about it from our customers and prospects in the field. Arriving on a troubleshooting scene with that extra level of credibility is always a good thing. What has been your greatest professional accomplishment? Being highlighted in the Analyst is right up there! The decades of conventions I've attended, the countless presentations I've watched, the pages of notes I've taken, the long list of conversations I've had with fellow water treaters, and the CWT designation I've earned have presented me with the ability to amass a long list of problems I have solved and questions I have answered. Those solutions and answers are my greatest professional accomplishments. What do you think are the most prominent issues facing the water industry today? The Information Age has changed everything. Where monthly service used to pass for following a system pretty closely, today's expectation is real-time information. Mastering the connectivity issues has never been easier, but it has presented us with an enormous volume of information to digest every day. Staying on top of it all and selling the value is a challenge and a real differentiator among industries.
Please join us in congratulating the latest individuals to become CWTs Roger Anderson, DuBois Chemicals Inc. Matt Brooks, Viking Water Technology, Inc. Brian Burgess, Global Water Technology, Inc. Jeff Burton, Ques Industries, Inc. Jeffrey Chan, Mandai Park Development Pivate Limited Jim Davis, WaterLink, Inc. Kevin Haskins, CH2O, Incorporated Gary Ho, The Metro Group, Inc.
Travis Long, Aqua-Serv Engineers, Inc. William Pagano, Adena Technologies Conor Parrish, FCT Water Treatment Kyle Rossi, Aqua-Serv Engineers, Inc. Kevin Thurston, Jamestown Technologies, A Division of Azure Water Services, LLC John Weddle, Technical Resources Group Jinapat Yoswattana, Chem Pro Laboratory, Inc.
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the Analyst Volume 25 Number 3
Ask the Experts The discussion below occurred on AWT’s listserv and/ or LinkedIn page. Be sure to join to be part of the conversation!
LEED Question
technologies such as filming amines and high molybdate also work but may be more costly (at least the molybdate one is which is what I used prior to 1998!!). Using RO permeate as cooling tower makeup is way too costly.
Response 1 I’m sure others can speak on LEED in more depth but simply by having a controller to regulate the cycles and time feed chemicals makes him LEED appropriate.
Response 6 For those who are reading this and questioning the effects of softening makeup water for cooling towers, no matter the makeup water quality, when softened, the COCs simply will have limiting factors other than hardness. So when the makeup is softened, the COC is not as you wish, it is just a factor other than hardness that limits the maximum COC. The chemistry is straightforward, but it is not so much so that softening will negate other influences. Suffice it to say that all attempts to increase the maximum COCs will have a cost for the associated equipment and maintenance; therefore, options should be carefully calculated to be sure of the benefit.
I have a new customer who wants his cooling tower system to be LEED appropriate and is also looking for 8-10 cycles of concentration. Any suggestions.
Response 2 Correct, and also by having water meters on the makeup and the blowdown lines. Response 3 Cycles of Concentration depends on makeup water. Depending on your water source, softening the water may help you achieve high cycles. Response 4 In the past, we have found it always a cost advantage to run hard vs. soft in cooling towers due to the corrosion inhibition package necessary to prevent carbon steel and copper corrosion. Since we started using filming amine for corrosion inhibition, the equation has shifted toward soft water due to higher cycles of concentration and the cost of water. The combination of soft/RO has significantly reduced bleed and is starting to show a payback after a couple of years. Just thought I would throw my two cents in on LEED. Response 5 Maximum COC with chemistry depends on the water quality. With softened makeup you can run whatever COC you wish, just have to address the corrosion problem. Using softened makeup does present a challenge as to keeping corrosion under control and there are several means to do it. I have two patents covering treatment of softened cooling water with silicate chemistry, which works well at a reasonable cost. Payback, including a softener, is generally less than a year. Other 71
Response 7 When running higher COC with softened makeup water, in addition to increased corrosivity to deal with, deposition and biological control become much more important. We use sidestream filtration with a multimedia filter for most cooling tower systems operating over 8 COC to address the deposition issue. Bromine is our current choice for biological control, as the pH of a high COC soft makeup system will be in the range of 9.5 to 9.8. Note that white rust is also a real issue if the CT are galvanized; we have installed several Delta CT as one means to completely eliminate the problem of white rust. Note our latest article on use of softened makeup water in CT in Water Conditioning & Purification, September 2017, for additional information. Bill Harfst also has a good paper, “Benefits of Soft Water Makeup for Cooling Tower Operation,” International Water Conference paper, 07-10, 2007.
Continued on p. 76 the Analyst Volume 25 Number 3
T.U.T.O.R.
Technical Updates, Tips, or Reviews
Dead Legs, Biofilms, and Legionnaires’ Disease: One Thing Can Lead to Another By Allan Browning, Chem-Aqua, Inc.
Dead Legs Cause Serious Problems
legs do not receive disinfectant or biocide treatment. Sediment accumulations in dead legs further support biofilm growth. Once established, biofilms and associated microorganisms provide a protective environment for problem-causing bacteria such as Legionella to multiply. Eventually, Legionella could be released into the bulk water to cause disease.
Dead legs are sections of a water system with low or no flow due to system design and/or operation. Common examples of dead legs include capped piping, closed cross connections, low point drains, cooling tower equalization lines, bypass lines, and out of service rooms or equipment. Intermittently operated faucets, showers, chillers, heat exchangers, and pumps can also be dead legs depending on how long they are out of service.
Established biofilms are tenacious and difficult to remove, even when subjected to high levels of chlorine or other disinfectants. The lack of flow and access for cleaning makes biofilms growing in dead legs especially difficult to remove. The best control strategy is to eliminate the dead leg. Where this is not practical, a combination of design, operational, and maintenance strategies is required to help manage biofilm problems resulting from dead legs.
Dead legs in building water systems can result in serious problems, including persistent positive Legionella test results and an increased incidence of Legionnaires’ disease. A basic understanding of dead legs, how to recognize them, and how to manage the problems they cause can help building owners reduce the risks associated with Legionella and other pathogens in their water systems.
Dead Legs, Biofilms, and Legionella
Biofilms can be a link between dead legs and Legionnaires’ disease. Biofilms are communities of surface-attached bacteria surrounded by a sticky, gel-like secretion often called slime. Although biofilms start out microscopic in size, they can grow into visible biofouling deposits in just a matter of days. A wide range of problem-causing microorganisms, including Legionella, can grow to high levels protected within biofilms and associated microorganisms, especially amoebae. The end result of biofilms include corrosion, clogged piping, reduced heat transfer, increased pumping costs, and increased potential for Legionella amplification.
Dead Legs and Biofilm Formation
Stagnant water in dead legs provides ideal conditions for biofilms to form. Without flow, planktonic bacteria can readily attach to system surfaces to start the biofilm formation process. Lack of flow also means that dead 72
Managing Dead Legs
Design: Design strategies involve mechanical alterations to provide continuous or intermittent flow. These strategies include removing dead legs or unused equipment, installing jumper piping across dead legs, and installing drain lines to allow flushing. As a general rule, terminated piping should extend less than 2X its diameter. Operational: Dead legs can also be managed by continuously or periodically establishing flow through offline piping and equipment in coordination with disinfectant or biocide additions. A common control strategy for cooling tower systems involves programming the building automation system to establish flow through offline system components (chillers, heat exchangers, pumps, piping, etc.) at least twice per week in conjunction with biocide feed. Likewise, tower basin equalization lines or low point drains can be automatically flushed using motorized valves and timers. the Analyst Volume 25 Number 3
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T.U.T.O.R. continued
Maintenance: Effective maintenance procedures are also required to help manage biofilms and dead legs. Systems or components that have been off line for more than a defined period of time (~five days) should be disinfected upon startup. Disinfection and physical cleaning may also be required in response to out-of-range microbiological test results. Itâ&#x20AC;&#x2122;s important to address any accumulated debris in equalization lines, drains, side stream filters, and remote sumps, and to ensure equipment and piping receive circulation during disinfection procedures. Cleaning adjuncts can be used to aid biofilm removal during disinfection processes. New Systems: The stagnant water associated with pressure testing new building water systems, or additions to existing systems, makes them particularly susceptible to biofilm-related problems. Even if the system is drained, trapped water can result in severe biofouling. New piping systems and additions should always be cleaned and disinfected just prior to startup. Dead legs in water systems can cause serious and costly problems. Design, operational, and maintenance strategies should be employed to help manage biofilm problems where dead legs cannot be eliminated.
Basin Equalization Line: Install drain line to flush two to three times per week during biocide additions. Automate with timer. Flush heavily to remove debris during twice a year cleaning and disinfection.
Out of Service Sand Filter: Replace sand. Disinfect housing and piping before operation if out of service > 5 days. To permanently decommission, remove filter and terminate piping.
Managing Common Cooling Tower System Dead Legs
Standby Chillers: (Open For Inspection) Establish flow through all offline equipment two to three times per week during biocide additions. Disinfect before operation if out of service more than five days.
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Free Cooling Heat Exchangers: Establish flow through all heat exchangers two to three times per week during biocide additions. Disinfect before operation if out of service more than five days.
the Analyst Volume 25 Number 3
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T.U.T.O.R. continued
Ask the Experts continued
Capped Expansion Piping: Remove dead leg or install drain line or cross connection to flush two to three times per week during biocide additions. Automate with timer.
Response 8 Regarding LEED-appropriate qualifications, we had worked directly with the USGBC when I was at SonitecVortisand Inc., a leading manufacturer of high-efficiency water filtration. There are two sets of LEED accreditation—new construction and existing buildings—which have different criteria for LEED credits. Vortisand was the first Green Accredited filtration company in North America at that time. They also received one LEED credit for every rainwater harvesting project they sold.
Standby Recirculation Pump: Rotate pumps or operate to establish flow two to three times per week during biocide additions. Disinfect before operation if out of service more than five days.
All the responses are accurate and true, whereas, I would look at installing high-efficiency filtration on all cooling towers right from the start. Many papers have been published supporting the use of sidestream filtration because 5.0 µ particles will adhere to surfaces first, followed by smaller particles, which leads to deposition issues on tower fill, chiller tubes, heat exchanger, control valves, and piping. This is why you must select a filtration technology that actually removes the harmful TSS by micron size. The filtration industry is basically nominal technology, and some companies will use that to their advantage in selling lesser efficient products. Particle Distribution Analysis (PDA) should always be conducted. I can supply reference material on this subject if you want them. As for Delta Cooling Towers, I had recommended a company to them years ago that manufactures a nano liquid antimicrobial compound, but I’m not sure if that is what they ultimately are using now. Great idea and design using a slopped sump, which helps to reduce low flow velocity areas such as tower sumps (reduced sludge buildup). However, it will allow the fine TSS to be reintroduced back into the main loop to settle out somewhere else. Thus, the need for efficient filtration.
Allan Browning is the vice president of engineering and technology at Chem-Aqua. He can be reached at (972) 438-0449.
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the Analyst Volume 25 Number 3
Capital Eyes
Semiannual Regulatory Agenda By Janet Kopenhaver
Twice a year, federal agencies publish their Regulatory Agendas and Regulatory Plans. The activities included in the agenda are, in general, those that will have regulatory action within the next 12 months. Below are regulations from the Environmental Protection Agency (EPA) that could impact water treatment companies, their suppliers, and/or their customers.
2010-AA12. Increasing Consistency, Reliability and Transparency in the Rulemaking Process
EPA is considering developing implementing regulations that would increase consistency across EPA divisions and offices, increase reliability to affected stakeholders, and increase transparency during the development of regulatory actions. Many EPA statutes, including the Clean Air Act and the Clean Water Act, provide language on the consideration of costs, but costs have historically been interpreted differently by the EPA depending on the office promulgating the regulatory action. This has led to EPA choosing different standards under the same provision of the statute, the regulatory community not being able to rely on consistent application of the statute, and EPA developing internal policies on the consideration of costs through non-transparent actions. By developing implementing regulations through a notice-andcomment rulemaking process, it will provide the public with a better understanding on how EPA is evaluating costs when developing a regulatory action and allow the public to provide better feedback to EPA on potential future proposed rules.
2040-AF84. Clean Water Act Methods Update for Rule for the Analysis of Effluent
This regulatory action would amend â&#x20AC;&#x153;Guidelines Establishing Test Procedures for the Analysis of Pollutantsâ&#x20AC;? to approve test procedures for use by testing laboratories and others for water monitoring. These test 77
procedures must be used to implement the NPDES program unless EPA has approved the use of an alternative procedure. This action approves new and revised versions of testing procedures for analysis and sampling under the CWA. The rule is expected to include primarily method revisions from voluntary consensus standard bodies and Alternate Testing Procedures that are comparable to the current methods. Generally, these changes will have a positive impact on NPDES permittees by increasing method flexibility, thereby allowing entities to reduce costs by choosing more cost-effective methods.
2040-AF25. NPDES Application and Program Updates Rule
EPA is developing a final rule to update specific elements of the existing National Pollutant Discharge Elimination System (NPDES) regulations. The rule would make targeted revisions to outdated application, permitting, monitoring, and reporting requirements in order to eliminate inconsistencies between regulations and application forms, improve permit documentation and transparency, and clarify existing regulations.
2070-AK33. TSCA Chemical Data Reporting Revisions
The Chemical Data Reporting (CDR) rule, under TSCA, requires manufacturers to provide the EPA with information, including processing and use information, on chemical substances that they manufacture above threshold production volumes. The information is collected every four years, and the production volume threshold for reporting a chemical substance is generally 25,000 pounds for a specific reporting year. Before the next reporting period in 2020, the EPA will be revising the reporting requirements to better align with new statutory requirements resulting from TSCA, as amended by the Frank Lautenberg Chemical Safety for the 21st Century Act.
the Analyst Volume 25 Number 3
Capital Eyes continued
2070-AK42. Parent Company Definition for Toxics Release Inventory
The Toxics Release Inventory (TRI) program is considering whether to codify a definition of “parent company” for reporting purposes. This rulemaking would clarify existing guidance and provide guidance for facilities owned by public entities, multiple entities, and entities with several layers of ownership. Providing this definition would clarify reporting requirements and increase the quality of TRI data by increasing consistency in the reporting of the parent company and improving trend analyses across ownership structures.
2070-AC46. Groundwater and Pesticide Management Plan Rule As proposed, this regulation would have established Pesticide Management Plans (PMPs) as a new regulatory requirement for certain pesticides. The rule would also specify procedures and deadlines for development, approval, and modification of plans by states. Several parameters of the program described in the proposed rule were reconsidered to determine whether the program could address water quality issues rather than groundwater only, and to determine the best partnership approach to implementation. During this period, the risk level associated with the named pesticides was reexamined and reduced. Moreover, since the proposal in 1996, many states have adopted the original concept and framework of PMPs, and these programs are operational today. This experience and growth in knowledge has exceeded the requirements and specifications of the original proposal. Accordingly, EPA intends to withdraw the proposed rule in the near future.
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2070-AJ94. Significant New Uses of Chemical Substances: Updates to the Hazard Communication Program and Regulatory Framework
EPA issued regulations in 1989 for the “Protection in the Workplace” and “Hazard Communication Program” components of the Significant New Uses of Chemical Substances regulation. Where possible, these regulations are closely aligned with OSHA regulations. OSHA issued a final rule on March 26, 2012, that aligns with OSHA’s Hazard Communication Standards with the Globally Harmonized System of Classification and Labeling of Chemicals (GHS). On July 28, 2016, EPA issued a rule proposing changes to the applicable Significant New Uses of Chemical Substances regulations to align with EPA’s regulations and, where possible, with the final revisions to the OSHA Hazard Communication Standards.
Janet Kopenhaver is president of Eye on Washington and serves as the AWT Washington representative. She can be reached at (703) 528-7822 or via email at janetk@eyeonwashington.com.
the Analyst Volume 25 Number 3
Business Notes
8 Questions to Ask Someone Other Than “What Do You Do?” By David Burkus, Harvard Business Review
We’ve all been in the awkward situation of meeting someone new and having to build rapport quickly—at networking events, industry conferences, charity events, dinner parties, and other social–professional situations. If you’re like many people—especially most Americans— you break the awkward silence with a pretty standard question: “So, what do you do?” But that question might not be the best way to build rapport with someone else. In fact, it may be best to avoid talking about work entirely. Research findings from the world of network science and psychology suggests that we tend to prefer and seek out relationships where there is more than one context for connecting with the other person. Sociologists refer to these as multiplex ties—connections where there is an overlap of roles or affiliations from a different social context. If a colleague at work sits on the same nonprofit board as you, or sits next to you in spin class at the local gym, then you two share a multiplex tie. We may prefer relationships with multiplex ties because research suggests that relationships built on multiplex ties tend to be richer, more trusting, and longer lasting. We see this in our everyday lives: The work friend who is also a “friend friend” is far more likely to stick with you should one of you change jobs. And it goes the other way, too: People who have at least one real friend at work report liking their jobs more. Which brings us back to the problem of using “So, what do you do?” as your opener. Assuming you’re already at a work-related networking event or meeting another person in a work context, the question quickly sets a boundary around the conversation 79
that the other person is now a “work” contact. It’s possible you might discover another commonality and build a multiplex tie, but it’s far less likely to happen in that conversation. Instead, consider beginning your introductory questions with something deliberately non-work-related and trusting that the context of the meeting will eventually steer the conversation back to work-related topics. Toward that end, here are a few questions you could start with that will leave you more likely to find multiple commonalties and turn your new contacts into a multiplex tie—and maybe even a friend: What excites you right now? This is a question that has a wide range of possible answers. It gives others the ability to give a work-related answer or talk about their kids, or their new boat, or basically anything that excites them. What are you looking forward to? This question works for the same reason, but is more forward-looking than backward-looking, allowing others to choose from a bigger set of possible answers. What’s the best thing that happened to you this year? Similar to the previous two, but reversed: more backward-looking than forward-looking. Regardless, it’s an open-ended question that gives others a wealth of answers to choose from. Where did you grow up? This question dives into others’ backgrounds (but in a much less assertive and loaded way than “Where are you from?”) and allows them to answer with simple details from childhood or to engage in their story of how they got to where they are right now and what they’re doing. What do you do for fun? This question steers the conversation away from work, unless of course they are lucky the Analyst Volume 25 Number 3
Business Notes continued
enough to do for work what they’d be doing for fun anyway. Even then, it’s understood as a non-work question, and the most likely answers will probably establish non-work ties. Who is your favorite superhero? This might seem random, but it’s one of my favorites. Occasionally, asking this question has led me to bond over the shared love of a character, but more often you’ll find a shared connection or two in the reason for why the other person chose that particular character…or why they’re not really into superheroes. Is there a charitable cause you support? Another big, open-ended question (assuming they support at least one charitable cause). It’s important to define support as broader than financial donations, as support might be in the form of volunteering or just working to raise awareness. You’re also really likely to either find shared ground or find out about a cause you didn’t know about.
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What’s the most important thing I should know about you? This one is effective for similar reasons as many of the above, plus it gives the broadest possible range from which they can choose. It can come off as a little forthright, so when to use it depends on a lot of contextual clues. Regardless of which question you choose, the important thing is to ask a question that is open-ended enough to allow others to select non-work answers if they choose. Doing so will increase the chances that you don’t just turn a stranger into a new contact on your phone, but that you actually make a new friend. David Burkus is the best-selling author of three books, including the forthcoming Friend of a Friend, and is associate professor of leadership and innovation at Oral Roberts University. Copyright © 2018 Harvard Business School Publishing Corporation. All Rights Reserved.
the Analyst Volume 25 Number 3
Financial Matters
Handle With Care: Mutual Funds and Taxes Many people overlook taxes when planning their mutual fund investments. But you’ve got to handle these valuable assets with care. Here are some tips to consider.
Avoid year-end investments Typically, mutual funds distribute accumulated dividends and capital gains toward the end of the year. But don’t fall for the common misconception that investing in a fund just before a distribution date is like getting “free money.”
mutual funds, which generally redeem shares by selling securities, ETFs are often able to redeem securities “in kind”—that is, to swap them for other securities. This limits an ETF’s recognition of capital gains, making it more tax efficient. This isn’t to say that tax-inefficient funds don’t have a place in your portfolio. In some cases, actively managed funds may offer benefits—such as above-market returns—that outweigh their tax costs.
True, you’ll receive a year’s worth of income right after you invest. But the value of your Watch out for reinvested distributions Directing tax-inefficient shares will immediately drop by the funds into nontaxable same amount, so you won’t be any Many investors elect to have their accounts better off. Plus, you’ll be liable for distributions automatically reinvested If you invest in actively managed taxes on the distribution as if you had in their funds. Be aware that those or other tax-inefficient funds, owned your shares all year. distributions are taxable regardless of ideally you should put these whether they’re reinvested or paid out holdings in nontaxable accounts, You can get a general idea of when a in cash. such as a traditional IRA or particular fund anticipates making a 401(k). Because earnings in these distribution by checking its website Reinvested distributions increase accounts are tax-deferred, distriperiodically. Also, make a note of your tax basis in a fund, so track your butions from funds they hold won’t have any tax consequences the “record date”—investors who own basis carefully. If you fail to account until you withdraw them. And fund shares on that date will particifor these distributions, you’ll end if the funds are held in a Roth pate in the distribution. up paying tax on them twice—once account, those distributions will when they’re paid and again when escape taxation altogether. you sell your shares in the fund. Invest in tax-efficient funds Actively managed funds tend to Fortunately, under current rules, mutual fund companies be less tax efficient. They buy and sell securities more are required to track your basis for you. But you still may frequently, generating a greater amount of capital gain, need to track your basis in funds you owned before 2012 much of it short-term gain taxable at ordinary income when this requirement took effect, or if you purchased units rates rather than the lower, long-term capital gains rates. in the fund outside of the current broker holding your units. Consider investing in tax-efficient funds instead. For example, index funds generally have lower turnover Do your due dilligence rates. And “passively managed” funds (sometimes Tax considerations should never be the primary driver of described as “tax managed” funds) are designed to your investment decisions. Yet it’s important to do your due minimize taxable distributions. diligence on the potential tax consequences of funds you’re considering—particularly for your taxable accounts. Another option is exchange-traded funds (ETFs). Unlike
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63 AMSA, Inc. 31 AquaPhoenix Scientific Inc. 5
Bio-Source, Inc.
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73 ProMinent Fluid Controls, Inc. 2
Pulsafeeder, Inc.
23 Pyxis Lab, Inc. 69 QualiChem, Inc. 8
Ques Industries, Inc.
75 Sanipur US LLC 60 Scranton Associates Inc. 84 Special Pathogens Laboratory 7 Univar 35 USABlueBook 53 Walchem, IWAKI America Inc. 83 Water Science Technologies 15 WaterColor Management
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