AWT Spring 2020 Analyst

the Analyst The Voice of the Water Treatment Industry

Volume 27 Number 2

1300 Piccard Drive, Suite LL 14 • Rockville, MD 20850

Spring 2020

Can Slow-Dissolving DBNPA Tablets Help Control Cooling Tower Biofouling?

Is Overstabilization of Stabilized Bromine a Significant Concern?

Can RO Concentrate Successfully Work as Cooling Tower Makeup?

Volume 27 Number 2 Spring 2020

Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants: An ASME Research Report

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Cover An industrial cooling tower.

Photo courtesy Adobe Stock.

Spring 2020

Volume 27

Number 2

8 Can Slow-Dissolving DBNPA Tablets Help Control Cooling Tower Biofouling?

Jonathan Howarth, Ph.D.; Carley Thompson; and Chrissa Easter, M.S., Enviro Tech Chemical Services In 2011, a type of slow-dissolving dibromonitrilopropoionamide (DBNPA) biocide tablet was introduced in a technical paper given at the Association of Water Technologies (AWT) Annual Convention. DBNPA tablets constitute the simplest biocide treatment option for cooling water. As these tablets primarily consist of inert ingredients, an insoluble residue remains after the tablets dissolve. Other problems of the tablets include swelling upon contact with water and fusion of swollen tablets.

Slow-dissolving DBNPA tablets leave behind no insoluble residue and do not swell upon water contact, thus giving them an advantage over the traditional tablets.

20 Is Overstabilization of Stabilized Bromine a Significant Concern?

Qilong Xu, Ph.D. (Southern Microbiological Services); Brian Nixon (Albemarle Corp.); William T. Doerrler, Ph.D. (Southern Microbiological Services and Louisiana State University, Department of Biological Sciences); and Eric Liimatta, Ph.D. (Albemarle Corp.)

The buildup of stabilizer in a cooling tower over time and the possibility of diminished biocidal efficacy is a concern, especially in cooling towers with high cycles of concentration. In this article, efficacy studies were done as a function of sulfamate levels to determine the effect on both planktonic organisms and biofilms.

Samples were taken from cooling towers treated with stabilized bromine so that the measured sulfamate levels could be compared to the biocidal performance.

30 Can RO Concentrate Successfully Work as Cooling Tower Makeup?

Timothy Keister, CWT FAIC, ProChemTech International, Inc. Evaporative, or "wet," cooling towers are the technology of choice for commercial and industrial cooling systems, as water is the best material for both transfer of heat and evaporative cooling. Such installations are many times the largest water consumers at the facility. Due to freshwater shortages in many areas and increased water and sewer charges, many facilities are now looking to reuse industrial wastewaters as cooling tower makeup. Often, facilities with cooling towers also have reverse osmosis treatment to purify incoming water for process use or boiler makeup.

4

Calendar of Events

5

President’s Message

6

Message From the President-Elect

63 Convention Preview 67 Membership Benefits 69 Association News 70 Industry Notes 73 CWT Spotlight 74 Making a Splash 75 Capital Eyes 77 Financial Matters 78 Business Notes 80 T.U.T.O.R. 86 Advertising Index

36 Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants: An ASME Research Report

By Edward S. Beardwood, Solenis LLC This article introduces the elements of a consensus report regarding precommissioning and highlights some of its features that will result in the construction of a plant with steam/water-wetted surfaces that are as clean and corrosion-free as practical. Issues can surface during the commissioning of a combined-cycle power plant that cause unintended delays, cost overruns, increased post startup maintenance, and depreciation of equipment. Consensus recommendations have been developed to minimize these risks and improve long-term reliability.

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the Analyst Volume 27 Number 2

1300 Piccard Drive, Suite LL 14 Rockville, MD 20850 (301) 740-1421 • (301) 990-9771 (fax) www.awt.org

2020 AWT Board of Directors President

Thomas Brandvold, CWT

Calendar of Events

Association Events 2020 Annual Convention & Exposition

Secretary

September 30–October 3, 2020 Louisville Convention Center and Omni Hotel Louisville, Kentucky

Treasurer

2021 Technical Training (West)

President-Elect

Michael Bourgeois, CWT Matt Jensen, CWT

February 24–27, 2021 Doubletree Mission Valley San Diego, CA

Stephen C. Hallier, CWT

Immediate Past President

David Wagenfuhr

Directors

Noah Baskin Mark Coldren, CWT Stephanie Keck, CWT Andy Kruck, CWT

2021 Technical Training (East)

Ex-Officio Supplier Representative

Garrett S. Garcia

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 Jr., 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 Marc Vermeulen, CWT David Wagenfuhr 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

Vice President, Meetings

Grace L. Jan, CMP, CAE

Meetings Manager

Ivy Caro, GCMP

Meetings Manager

Morgan Prior

Exhibits and Sponsorship Manager

Barbara Bienkowski, CEM

Marketing Director

Jennifer Olivares

Technical Writer/Copy Editor Lynne Agoston

Accountant

Dawn Rosenfeld

The Analyst Staff

Publisher, Heidi J. Zimmerman, CAE Managing Editor, Lynne Agoston Production Manager, Maryia Alenchyk Technical Editor Michael Henley (303) 745-3890 mdhenleywater@gmail.com

Advertising Sales

Heather Prichard advertising@awt.org

The Analyst is published quarterly as the official publication of the Association of Water Technologies. Copyright 2020 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, 1300 Piccard Drive, Suite LL 14, 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.

March 17–20, 2021 Graduate Annapolis Annapolis, MD

2021 Annual Convention & Exposition

September 22–25, 2021 Providence Convention Center and Omni Hotel Providence, Rhode Island

2022 Annual Convention & Exposition September 21–24, 2022 Vancouver Convention Centre Vancouver, Canada

2023 Annual Convention & 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.

Second Tuesday of each month, 11:00 am – Legislative/Regulatory Committee Second Tuesday of each month, 2:30 pm – Convention Committee Second Wednesday of each month, 11:00 am – Business Resources Committee Second Friday of each month, 10:00 am – Special Projects Subcommittee Second Friday of each month, 11:00 am – Cooling Subcommittee Second Friday of each month, 2:00 pm – Pretreatment Subcommittee Third Monday of each month, 9:00 am – Certification Committee Third Monday of each month, 3:30 pm – Young Professionals Task Force Third Tuesday of each month, 3:00 pm – Education Committee Third Friday of each month, 9:00 am – Boiler Subcommittee Third Friday of each month, 10:00 am – Technical Committee Quarterly (call for meeting dates), 10:00 am – Wastewater Subcommittee

Other Industry Events

ASHRAE, Virtual Conference, June 29–July 2, 2020 BOMA, International Conference & Expo, Live via Webcast, July 7–9, 2020 ACS, Fall National Meeting & Expo, August 16–20, 2020, San Francisco, California NACE, Corrosion Technology Week, September 13–17, 2020, Houston, Texas WEFTEC, Annual Technical Exhibition and Conference, October 3–7, 2020, New Orleans, Louisiana

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President’s Message

By Tom Brandvold, CWT

These are challenging times we find ourselves in. As I write this, we are in the midst of the COVID-19 crisis. It’s hard to know what tomorrow will bring, let alone what we will be dealing with when this magazine reaches you.

In these uncertain times, community is more important than ever. It seems like that word “community” is being thrown around a lot lately, but the best way to navigate these uncharted waters is together.

For all of us, normal day-to-day routines have been upended. For some members, regional or state lockdowns have meant explaining to officials why water treatment is an essential business. For other companies, business goes on, but the facilities we treat are needing less service, as once bustling schools and office buildings find themselves virtual ghost towns. On a personal level, many of our home lives have been altered by having kids home doing distance learning.

It has been heartening to see how our AWT community has come together, sharing resources both online and in person. As a business owner, the resources we share with one another have been critical to navigating through this crisis. And on a personal level, my friendships with my AWT colleagues have been a lifeline.

As the economic impact of this virus becomes clearer in the coming weeks, I hope you continue to rely on the AWT community. You’ll notice that we recently enhanced the website, making it easier to navigate and connect with one another. Be sure to visit the Members Only page to download the myriad of articles and white papers available to you. If you haven’t already, be sure to sign up for the Exchange, AWT’s online, members-only community. COVID-19 and stimulus package information are being regularly updated on this forum. And finally, you can use the AWT calculations app on your phone as a mobile download or on the website if you’re at the office.

At the board level, we conducted our first-ever virtual meeting at the end of April. Your board will be taking action on a number of exciting projects and initiatives that will enhance how membership is served and will strengthen your association.

I look forward to seeing you at the AWT Annual Convention later this year! Thank you for the opportunity to serve. I can be reached at carmac@premierwater.com.

Tom Brandvold President

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Message From the President-Elect

By Michael Bourgeois, CWT

Convention

These certainly are challenging times. I’ve been struck by the fact that now, more than ever, there is a need for continued online training, and when it’s deemed safe, returning to in-person training.

Planning is moving forward with the Annual Convention & Exposition from September 30– October 3. As of the printing of this issue of the Analyst, we are hopeful we can meet in person in Louisville, Kentucky, but if we are unable, we will still have an exciting and robust virtual meeting. We have a very strong educational program with some new topics and great panels and workshops. I hope you prioritize the Louisville meeting as an important one to attend.

I had the pleasure of attending the AWT Technical Training Seminars earlier this year. I’m so impressed by the quality of the training and the dedication and expertise of our volunteer trainers. The sessions I attended were top notch. Our company uses the in-person training to supplement our own in-house training, as well as the other online training options that AWT provides.

Make no mistake, attending the convention is an expense—there are the actual costs of travel and registration, plus the cost of having people out of the field.

But going to the convention is an investment that pays dividends.

Speaking of online training, I’ve had the honor of working on the “Introduction to Water Treatment” online modules. Developing these modules has been a herculean task and has taken longer than anticipated.

However, the need for this training has been highlighted as in-person gatherings are put on hold. As I write this, our development task force is in the final stage of getting the modules online. We will be excited to push these out to the membership. Be sure to take advantage of these free courses. They are a great benefit of membership.

It’s easy to get lost in the daily routine of work, but getting a break from the norm and networking with new and old friends is a great way to stay motivated.

Everyone comes back from the convention with new pieces of knowledge that we implement to make ourselves and our companies better. We’re energized when we return and have a renewed sense of purpose.

The bottom line is, you cannot afford to miss the meeting in Louisville.

As we continue to plan the 2020 Convention, I welcome your feedback. I can be reached at mbourgeois@chemcoprod.com. Thank you for the opportunity to serve.

6

the Analyst Volume 27 Number 2

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Can Slow-Dissolving DBNPA Tablets Help Control Cooling Tower Biofouling?

Jonathan Howarth, Ph.D.; Carley Thompson; and Chrissa Easter, M.S., Enviro Tech Chemical Services

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Introduction

Experimental Materials and Methods/ Laboratory Testing

In 2011, a type of slow-dissolving dibromonitrilopropoionamide (DBNPA) biocide tablet, now commercially available, was introduced in a technical paper given at the Association of Water Technologies (AWT) Annual Convention (1). DBNPA tablets constitute the simplest biocide treatment option for cooling water because of their ease of application.

An APTech Group enduroTEQ Ultra-S feeder was obtained from Chem-Aqua Inc. and installed in the research laboratoryA. Installation was completed according to the user manual except for the following modifications:

½-inch outside diameter (OD) tubing was used for both the overflow and the outlet lines. The outlet fitting was changed to accommodate the larger tubing.

This was done to ensure constant spraying of the feeder and to prevent any inadvertent DBNPA particle accumulation in the tubing from tablet fragments that may have passed through the mesh screen cap.

Traditional DBNPA tablets consist of 40% solid DBNPA as the active ingredient, with a 200-gram (g) tablet required for use in 500 to 1,000 gallons (gal) of water. As these tablets primarily consist of inert ingredients, an insoluble residue remains after the tablets dissolve. Other problems with traditional DBNPA tablets include swelling upon contact with water and fusion of swollen tablets. Slow-dissolving DBNPA tablets leave behind no insoluble residue and do not swell upon water contact. Due to the increased DBNPA content, one 100-g tablet treats the same volume of water as traditional 200-g tablets. Taken together, these properties give the slow-dissolving DBNPA tablets an advantage over the traditional tablets.

¼-inch OD tubing was used for the inlet line to allow connection to existing water system in place at the lab.

An analog pressure indicator was installed along the inlet line to monitor water pressure during use.

A 3/8-inch hole was drilled in the mesh screen covering the tablets so that the entire water spray entered the tablet capsule and no water was allowed to rebound off the screen and not contact the tablets. (See Figure 2).

Although formally a nonoxidizing biocide, it is known that one of the two bromine atoms in DBNPA possesses some oxidizing properties. Indeed, it is this oxidation property that forms the basis for its determination; iodometry is used to determine the wt. % of DBNPA in DBNPA products. The total chlorine DPD reagent (which contains KI and is oxidized to I 2) is used for analysis of parts per million (ppm) DBNPA in solutions at use-dilution by use of a colorimeter.

Here is a summary of the characteristics of a typical dissolution test used to establish this novel method: APTech Group enduroTEQ Ultra-S feeder.

Capsule with a 100-millimeter (mm) neck opening from C. L. Smith (part number 09-1270IND).

Figure 1: Structure of DBNPA.

Capsule equipped with 100-mm locking neck finish mesh screen with 0.055-inch square mesh openings from Viking LLC (part number VOA LOCK B V98).

Mesh drilled with ⅜-inch hole.

Previously, slow-dissolving DBNPA tablets were limited to use in conventional bromine feeders, floaters, mesh bags in sumps, or placement directly into the tower sump. This article reports on a novel method for DBNPA treatment through use of a metering dissolution feeding system.

Capsule charge—5.8 lb (26 tablets) of slow-dissolving DBNPA tablets.

Run time DBNPA tablets alone—4x1 hours per day every day.

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Can Slow-Dissolving DBNPA Tablets Help Control Cooling Tower Biofouling?

Run time DBNPA tablets + bromochlorodimethylhydantoin (BCDMH).

continued

Figure 3: (Left) The enduroTEQ Ultra-S dissolver. (Right) Capsule containing 5.8 lb (26 tablets) of slow-dissolve DBNPA and tablets for reference.

Feedwater pressure—30 pounds per square inch (psi).

Feedwater temperature—60 °F to 65 °F. Figure 2: Modified mesh screen for capsule.

Analytical Methods The dissolution feeder was wall-mounted and fresh water was used. Water pressure was adjusted to 30 psi. The water was then guided to a spray nozzle housed inside the feeder. The spray was directed through the hole in the mesh and into the inverted capsule containing the tablets. To maximize outflow rate and prevent the feeder reservoir from filling and automatically turning the water inflow off, ½-inch OD diameter pipe and fittings were used for the feeder outlet. This allowed the rate of the freshwater flow in to be the same as the DBNPA effluent out (to the water being treated). Thus, the internal reservoir never filled, and the ultrasonic level indicator that activated a solenoid to cut the freshwater flow was never employed in any of the dissolution runs reported in this article, allowing for maximized dissolution rates of the tablets. Consequently, there was never any need for the safety overflow to be engaged.

Figure 3 shows the enduroTEQ Ultra-S dissolver (left) and the container containing 5.8 lb (26 tablets) of slow-dissolve DBNPA and tablets for reference (right).

Flowrate testing. Flowrate testing was performed by taking a 6-liter (L) beaker to collect outflow, and the time required to collect 5 L was recorded. From this, the flowrate was calculated in terms of min/5L. DPD residual testing. DBNPA residuals in the water dispensed by the feeder were determined by modified DPD testing. Within 15 minutes of flowrate testing, a sample of water from the feeder was taken and diluted with reverse osmosis (RO) water. Dilutions were either 1:100, 1:200, or 1:500 by mass, depending on the results of the DPD testing (i.e., if the 1:100 dilution was above the limit of the colorimeter, a greater dilution was used, and if the reading at a greater dilution was extremely low, a lesser dilution was used). Care was taken to ensure that no particles of DBNPA were collected in the sample to be diluted and tested. 10 milliliter (mL) of the diluted sample was placed in a glass vial and used to zero a Hach Chlorine Pocket Colorimeter (Model 46700-00). A DPD Total Chlorine Reagent Pillow pack was added to the vial, mixed well, and allowed to develop for 3 minutes. The total chlorine reading in ppm was taken and converted to ppm DBNPA by Equation 1.

Total Cl 2 Reading x 1.7 x dilution = ppm DBNPA Eq. 1

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Can Slow-Dissolving DBNPA Tablets Help Control Cooling Tower Biofouling?

The number 1.7 is the interchangeability factor for chlorine (molecular weight [MW] 71) and DBNPA (MW of 241.9). To convert, a ratio of the MW is used (241.9/71 = 3.4). This number is divided by 2 because only one bromine atom on DBNPA is reactive to the DPD total chlorine indicator.

DBNPA concentrations in the outflow were recorded, and readings resulting from different dilutions of the same outflow collection were averaged.

Daily tablet usage. The daily tablet usage of the feeder for each test period was determined using the flowrate and the average DBNPA residual concentration for that test period. The daily tablet usage was calculated as if the feeder were operating continuously for 10 hours per day, and the outflow DBNPA concentration remains constant throughout the entire operating time. Daily tablet usage was calculated as shown in Equation 2.

continued

Eq. 2

Results and Discussion

Flowrate and DPD residual testing were both performed at each sampling interval during the dissolution runs.

Tablet usage was calculated based on each reading. Using the DBNPA residual concentration and the flowrate, a theoretical number of tablets used per day was determined. This value assumes that the concentration of DBNPA is consistent throughout the day and at the same concentration as determined during that particular testing period, that the flowrate never varies, and that the feeder is operating for 10 hours per day.

Figure 4 is a graphical representation of the DBNPA concentrations in outflow over time.

Figure 4: Graphical representation of DBNPA concentrations in outflow over run time.

Early in the dissolution test, the DBNPA concentration in the effluent is fairly constant at around 300 ppm. It is conjectured that during this period, the water spray is only contacting the first one or two tablets and the mouth of the capsule. Subsequently, the spike in the DBNPA concentration between 12 and 18 hours of run time represents the “breakthrough� of the water spray as it contacts the entire bed of tablets in the capsule. This is visually corroborated by the water spray contacting the top of the inverted capsule. The ensuing decline in the DBNPA concentration in the effluent signifies a decreasing bed height of tablets with continued dissolution.

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Can Slow-Dissolving DBNPA Tablets Help Control Cooling Tower Biofouling?

continued

“The most striking observations are the traces of blistering and spalling on the untreated coupons oxidized without tannins.�

When dissolution is nearly complete at 32 hours, almost the entire bed of tablets has been depleted and DBNPA concentration in the effluent from the feeder falls to below 100 ppm. The experienced water treater will know that the capsule should be changed around 27 hours of total run time. At this point, the capsule should be removed from the feeder and the mesh pried off with a screwdriver. Undissolved DBNPA tablets in the near-depleted capsule are then transferred to a fresh capsule so that nothing is wasted. It is to be noted that snap-on meshes are preferred over screw-on meshes, as these can unscrew during service and empty the contents of the capsule.

The full-empty dissolution profile was replicated two more times. Each run yielded a near-identical chart as that displayed in Figure 4. In each case, tablet dissolution was complete and proceeded without residue or plugging of the feeder.

Application of Findings

Based on the dissolution profile of the slow-dissolve tablets and the required dosage per gallon of water to be treated, a dosage rate was determined for use with the feeder. Feed rates of every day, every other day, and every three days were determined for system volumes of 500 to 5,000 gal. of water.

Using the study findings, the device can dissolve 90 to 100-g DBNPA per day (approximately one tablet) using the conditions employed in this study. Since one 100-g tablet is used to treat 500 gal of water in a three-week period, the daily feed time can be calculated for the amount of water requiring treatment.

Figure 5 is a graphical representation of a calculation on the use of the slow-dissolve DBNPA as dispensed by the tablet feeder. The data is based on laboratory findings.

Figure 5: Tablet feeding dosage time by system volume. The black line represents the weeks until depletion of the capsule.

12

the Analyst Volume 27 Number 2

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Can Slow-Dissolving DBNPA Tablets Help Control Cooling Tower Biofouling?

Field Studies

Field trials involved the use of the DBNPA on cooling water at a local California winery that had a history of suffering leaks of wine juice high in sugars and were under marginal microbiological control. One DBNPA capsule feeder was used to supplement the existing BCDMH program (Tower 8) and the other delivered just DBNPA as the sole biocide (Tower 7) (Figure 6).

The other two control towers employed in the study remained on BCDMH alone. The efficacy of the respective biocide programs was monitored for a summer season. Figure 7 shows the DBNPA tablet feed systems used on Towers 7 and 8.

continued

Figure 6: Cooling towers 7 and 8 that were used in the field trials for this report.

Figure 7: Tablet feeders on Towers 7 and 8.

Here are the specifications for the cooling towers used in the research:

Table A summarizes the water quality in the two test towers.

Manufacturer: Baltimore Air Coil Co., Model No. VCA-1010A Type: Forced flow cooling tower Volume: 800 U.S. gallons Tower blowdown: Approximately 400 U.S. gal/day Water half-life: Holding time index of 1.7 days Cycles of concentration: 1.3 to 1.6 Purpose: Used to cool ammonia refrigeration system for wine

Table A: Water quality of test towers Water Source

pH

Conductivity (μS/cm)

Tower 7 Makeup Water

7.08

1,123

Tower 7 Recirculating

8.88

1,770

Tower 8 Makeup Water

7.83

889

Tower 8 Recirculating

8.87

1,431

“Care was taken to ensure that no particles of DBNPA were collected in the sample to be diluted and tested.”

14

the Analyst Volume 27 Number 2

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Can Slow-Dissolving DBNPA Tablets Help Control Cooling Tower Biofouling?

continued

Prior to cooling tower applications, samples of water from the cooling towers were taken. The decomposition of DBNPA in the water samples was studied to provide the specific decay profile. The results can be seen in Figures 8 and 9.

Figure 8: Profile of DBNPA in cooling tower water.

Figure 9: Half-life of DBNPA in cooling tower water.

Each test tower was fed twice a day with DBNPA, at 10 am and 10 pm. The DBNPA-only tower (Tower 7) was fed for 30 minutes, with a concentration of 0.8 to 1.2 ppm DBNPA after feeding, and Tower 8 was fed for 15 minutes, resulting in 0.3 to 0.7 ppm DBNPA after feeding. Tower 8 also had a supplementary BCDMH feeding schedule with 2 minutes feeding at 6 am and 8 pm and 3 minutes feeding at 10 am and 1 pm. The DBNPA feeder effluent was collected after 5 minutes of feed time and tested, with a resulting effluent concentration of 158.27 ppm of DBNPA.

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Can Slow-Dissolving DBNPA Tablets Help Control Cooling Tower Biofouling?

continued

length and lack of height needed for gravity flow to the tower. Lastly, an initial flow resistance has been speculated to be due to the forced flow mechanism within the tower pushing air out through the tubing.

Bulk water samples were collected pre- and postfeeding and plated for aerobic bacteria. Dilutions were made at 10 –2 and 10 –4 before plating. Both dilutions were enumerated and averaged for each sample.

Microbiological results can be seen in Figure 10.

In the field trials, a number of obstacles were encountered. Initial installation of the feeders involved using the included effluent tubing. The tubing was too small for continual feeding, resulting in erratic feeding during on times. Once this was noticed, the tubing was replaced with ½-inch OD, as in the laboratory setup. The new effluent tubing exhibited clogging during feeding. This was attributed to friction within the effluent line due to

The flow-resistance problem was overcome by removing the effluent tube from the tower until DBNPA effluent ran continuously through the tubing, then reinserting the tube into the tower. This allowed the effluent to continue flowing into the tower. A long-term solution is to redirect the end of the effluent tubing to below the water level within the reservoir of the cooling tower or to ensure that feeding does not run counter to the air flow from the fans.

Figure 10: Microbiological residuals of the towers pre- and post-DBNPA feeding.

Conclusions

Based on our research, we made the following conclusions from this study that examined the use of solid-form DBNPA alone or in conjunction with BCDMH tablets: Single DBNPA tablets are simply introduced to a cooling tower sump (1 x 100-g tablet /500 gal) and offer continuous release of DBNPA to the treated water.

Use of the tablets in a capsule dissolution feeder permits administration of the same dose in a much more controlled manner. The feeding device is capable of accurately metering a controlled dose of DBNPA to the cooling water.

Dissolution studies presented in this article define the active water flow time for sufficient dissolution to be accomplished.

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Can Slow-Dissolving DBNPA Tablets Help Control Cooling Tower Biofouling?

continued

“The experienced water treater will know

Endnote

that the capsule should be changed

A

around 27 hours of total run time.”

The laboratory mentioned in the text is located at Enviro Tech Chemical Services’ facility in Modesto, California.

British-educated Jon Howarth, Ph.D., has worked his entire career in the U.S. specialty chemical industries. Over the years, he has accrued 38 U.S. patents. More recently, he spent the last 17 years as senior VP of technology for Enviro Tech Chemical Services. Dr. Howarth has co-invented and commercialized many items, from “instant pool conditioner” to BromMax, which is a stabilized bromine biocide. His humorous mind keeps the lab environment spirits lifted without a doubt.

DBNPA and BCDMH tablets are chemically compatible.

Depending on the volume of the cooling water, a 5 lb DBNPA tablet capsule will last between 6.4 to 6.5 weeks. In a cooling tower with supplementary BCDMH treatment, the DBNPA capsule will last even longer.

A method for measuring low levels of DBNPA in cooling water has been developed for service in the field. The test is based on a modification of the DPD Total Chlorine method and employs a colorimeter.

It is possible to run a microbiological treatment program of a cooling tower on DBNPA tablets alone.

The consumption of DBNPA tablets in a microbiological treatment program is half when DBNPA is fed in conjunction with BCDMH.

Acknowledgements

The authors would like to thank Chris Binfield of Blue Tech Water Labs for allowing the use of their cooling towers as locations for the field trials. The authors also appreciated the help offered by Matt Horine of APTech Inc. in supplying the chemical feeders used in the field trials.

Reference

1. Harvey, M.; Shaver, T.; Howarth, J. (September 2011). “New, Slow-Dissolving DBNPA Tablets for Biocidal Treatment of Small Cooling Water Systems,” AWT fall conference, Atlanta, Georgia.

18

Chrissa Easter, M.S., has been a research chemist at Enviro Tech Chemical Services since 2018. She earned a B.S. in 2013 and an M.S. in 2016, both from University of the Pacific in Stockton, California. She has worked in conjunction with R&D and quality control while at Enviro Tech. When not immersed in chemistry, she is mom to an energetic 2-year-old.

Carley Thompson was born and raised in the Central Valley of California. She attended Modesto Junior College before she started working at Enviro Tech Chemical Services in 2010. Ms. Thompson became a quality control lab technician in 2010 and now has been the lab supervisor for more than three years. She has worked with R&D on new EPA and FDA formulations as well as analyzing all products produced respectively for Enviro Tech. Ms. Thompson is a painter and dog-lover from Modesto, California.

This technical paper was presented at the 2019 AWT Annual Convention, which was conducted September 11–14, 2019, in Palm Springs, California.

the Analyst Volume 27 Number 2

19

the Analyst Volume 27 Number 2

Is Overstabilization of Stabilized Bromine a Significant Concern?

Qilong Xu, Ph.D. (Southern Microbiological Services); Brian Nixon (Albemarle Corp.); William T. Doerrler, Ph.D. (Southern Microbiological Services and Louisiana State University, Department of Biological Sciences); and Eric Liimatta, Ph.D. (Albemarle Corp.)

Abstract

The buildup of stabilizer in a cooling tower over time and the possibility of diminished biocidal efficacy is a concern, especially in cooling towers with high cycles of concentration. There is certainly some precedent for this concern as chlorine in swimming pools can be overstabilized by cyanuric acid. It has been speculated that having a certain level of stabilizer in a cooling tower would indicate that the biocide is overstabilized. However, we are unaware of any studies examining overstabilization in any detail. In this article, efficacy studies were done as a function of sulfamate levels to determine the effect on both planktonic organisms and biofilms. Lastly, samples were taken from cooling towers treated with stabilized bromine so that the measured sulfamate levels could be compared to the biocidal performance. In all of these cases, high levels of sulfamate (>100 parts per million [ppm]) did not significantly hinder the biocidal performance. In the biofilm studies, sulfamate levels greater than 150 ppm were required to observe degradation in biocide performance.

Introduction

The commercialization of stabilized liquid bromine in the late 1990s has provided a powerful new tool in the arsenal to control bacteria in a cooling tower. This material uses sulfamic acid as the stabilizer. Stabilized liquid bromine is a stable, easy-to-feed, single-component biocide, which has significantly enhanced efficacy over chlorinated biocides at the alkaline pH values typically observed in the cooling tower. Stabilized bromine was so successful that it and bleach are now the most widely used oxidizing biocides in industrial water treatment.

Much of this enhanced storage stability is because of the addition of a stabilizer. While there are several possible stabilizer options, sulfamic acid is currently the most widely used. Figure 1 demonstrates how the active biocide is generated when added to water.

Figure 1: The hydrolysis of stabilized bromine in water to prepare the active biocide.

21

Sporadic anecdotal reports from the field, however, indicate that the halogen residual that once provided the desired level of microbiological control was no longer providing the same level of control, even though there was no apparent change in the system. One possible explanation for this observation is overstabilization.

Overstabilization may occur when there is a large excess of sulfamic acid stabilizer present, and the hypobromous acid becomes very tightly bound and thus less available to kill bacteria. As one might expect, overstabilization would be more likely to occur in cooling towers with high cycles of concentration.

Despite the concern about overstabilization, and the long period of commercial use of stabilized bromine products, we are unaware of any published data on this topic. Some members of the industrial water treatment community have suggested that if the cooling tower contains above a certain ppm level of sulfamate, the cooling tower is overstabilized. One biocide supplier has suggested that if the ratio of sulfamate to available bromine in the water is over 20, the cooling tower is overstabilized. While these points of view may be accurate, we are unaware of any data supporting these observations.

The authors’ view on this issue is a little more nuanced.

Our belief is that the level of sulfamate in the water required for overstabilization will depend on conditions in the cooling tower. Thus, there is no single number for the sulfamate level that one can measure and definitely assert whether a cooling tower is having issues with overstabilization. In this article, we will present planktonic data, biofilm data, and real-world data on the effects of sulfamate levels on biocidal efficacy to support this view.

Materials and Methods

ƒ Experimental materials used in the studies included a stabilized bromine biocide.A All other chemicals and growth media were purchased from Thermo-Fisher.

Dip slides were from Solar Biologicals Inc. ƒ Synthetic water (SW) was prepared by adding 0.22 grams (g) of calcium chloride (CaCl 2) and 0.168 g of sodium bicarbonate (NaHCO3) to 1 liter (L) of deionized water (DW). The water had 150 ppm of alkalinity (as calcium carbonate [CaCO3]), and 200 ppm Ca hardness (as calcium carbonate [CaCO3]) and a pH of approximately 8. the Analyst Volume 27 Number 2

Is Overstabilization of Stabilized Bromine a Significant Concern?

continued

Before each use, Escherichia coli (ATCC BAA1427) or Pseudomonas aeruginosa PAO1 was cultured in tryptic soy broth (TSB) overnight and cultured again for 16 hours (h). The recultured bacteria were pelleted by centrifugation at 5,000 revolutions per minute (rpm) for 10 minutes (min) and washed once in phosphatebuffered saline (PBS, NaCl 8.0 g/L, potassium chloride [KCl] 0.2 g/L, disodium phosphate [Na 2HPO4] 1.44 g/L, monopotassium phosphate [KH 2PO4] 0.24 g/L) and resuspended in PBS to 8.5 log colony forming units per milliliter (CFU/mL).

Halogen solutions or synthetic water (9 mL) and prepared bacteria (1 mL) was mixed and incubated at room temperature with 200 rpm orbital shaking. At 5 min, 30 min, 60 min, or 120 min, 1 mL from each mixture was transferred to 9 mL of 0.1% buffered peptone water containing 0.05% thiosulfate (BPWT) and mixed well. Each solution was tested in duplicate.

The solutions from each treatment were 10x diluted in BPWT. Aerobic petri-film counts (APC, 3M) were used for the colony counts of E. coli and P. aeruginosa.

Pseudomonas aeruginosa (ATCC 27853), which had been maintained on Luria Broth (LB) agar at 4 °C, was cultured in LB broth at 37 °C for 18 to 20 h. Cells were centrifuged at 5,000 rpm for 5 min, washed twice with phosphate-buffered saline (PBS, pH 7.4), and re-suspended in LB broth. Cell density was adjusted to 0.25 at the optical density 600 nanometers (nm) (OD600). To each well of 96-well plate (treated, Corning), 200 microliter (µL) of the resuspended solution was added. The plate was wrapped with a single layer of Parafilm and put in an autoclave tray.

The plate was covered with 8 to 10 layers of warm, wet paper towels. The tray was covered with aluminum foil and incubated overnight (18 to 24 h) at 37 °C oscillated at 72 rpm.

temperature for one hour without shaking. Biocides were removed and the wells were washed three times with sterile water by aspiration from highest to the lowest concentration (Figure 2A). 210 µL LB or sterile water was added. The plate was sealed with a layer of Parafilm and incubated overnight at 37 °C without shaking. The regrowth was visually read, based on the appearance of the wells (Figure 2B). The lowest concentration of biocide that did not allow bacterial regrowth (thus complete kill of the bacteria in the well) is called the minimum biofilm eradication concentration (MBEC).

The sulfamate levels in the cooling water samples were measured by ion chromatography on a Thermo Scientific Dionex ICS-5000 5000 instrument using a potassium hydroxide (KOH) eluent generator and a conductivity detector for anions.

Figure 2: 2A (top) shows the measurement of biocidal efficacy against bacterial biofilm using a 96-well plate.

After biofilm growth for 24 h, media is removed and wells washed with water. Biocides are applied in triplicate to Row A, followed by serial dilutions in Rows B-F as shown.

Following incubation with stabilized bromine, wells are washed, growth media is added, and plates are incubated to allow detection of surviving biofilm. Untreated biofilms and media-only (cell-free) wells are included as controls (called reference in 2A). 2B (bottom) shows a 96-well plate after regrowth. The clear well indicates complete kill of the biofilm bacteria (no growth). Turbidity indicates incomplete kill of the biofilm bacteria (growth).

To avoid contamination, all treatments were performed in a biosafety hood. The growth media from the 24-h biofilm culture was removed from the 96-well plate by aspiration. The plate was washed twice with 200-µL sterile water and once with 220-µL sterile water.

Biocides were serially diluted and were applied with 300-µL/well as triplicates per the matrix described in Figure 2A. The plate was incubated at room 22

the Analyst Volume 27 Number 2

Is Overstabilization of Stabilized Bromine a Significant Concern?

continued

Results

Our first efforts to examine the effects of sulfamate levels on biocidal efficacy were with planktonic bacteria.

These were time kill studies. Pure bacterial cultures were used for this work to ensure that if multiple tests were required, the test matrix would be the same for each test.

Please note that the sulfamate level noted in the tables is in addition to the stabilizer that is already contained in the product. In Table A, the test bacteria are E. coli.

It is very clear that the sulfamate levels greatly affect the efficacy at shorter contact times. However, at longer contact times (and certainly very reasonable contact times for a cooling tower) complete kill was achieved, even with 100 ppm additional sulfamate added.

Table A: E. coli Time Kill Study 5 min

30 min

60 min

120 min

5 ppm

4.3

ND

ND

ND

5 ppm + 25 ppm SA

0.16

5.20

ND

ND

5 ppm + 50 ppm SA

0.02

6.02

ND

ND

5 ppm + 100 ppm SA

0.00

2.02

5.25

ND

Notes: ND = not detected (complete kill) SA = Sulfamate The initial titer was 8.36 log CFU/mL of bacteria. The solution pH is 8.0. The data in Table A represents log reduction.

To observe the effects of a very large excess of sulfamate (560 ppm), the study summarized in Table B was performed. In this case, the efficacy of the biocide is severely degraded. In this instance, the solution with the excess sulfamate shows less efficacy at 60 min than the solution with no excess stabilizer at 5-min contact time.

This solution is clearly overstabilized.

Table B: E. coli Time Kill Study With 560 ppm Sulfamate 5 min

30 min

60 min

5 ppm

2.29

ND

ND

5 ppm + 560 ppm SA

0.07

0.08

0.25

Notes: ND = not detected (complete kill) SA = Sulfamate The initial titer was 8.72 log CFU/mL of bacteria. The solution pH is 8.0. The data in Table B represents log reduction.

We repeated this experiment with a different bacterium to see if the behavior observed for E. coli was typical. For this next set of experiments, a bacteria commonly found in cooling towers (P. aeruginosa) was used. As shown in Table C, very similar behavior was observed. At short 23

contact times, the addition of sulfamate reduces biocidal efficacy, but again, even with the addition of 100 ppm additional sulfamate, acceptable biocidal efficacy is achieved at longer contact times.

Table C: Pseudomonas aeruginosa Time Kill Study 5 min

30 min

60 min

120 min

7.5 ppm

2.14

6.11

ND

ND

7.5 ppm + 25 ppm SA

0.03

2.77

5.36

6.76

7.5 ppm + 100 ppm SA

0.01

2.32

3.96

7.14

10 ppm

3.00

7.76

ND

ND

10 ppm + 25 ppm SA

0.1

5.33

7.76

ND

10 ppm + 100 ppm SA

.03

3.62

7.76

ND

Notes: ND = not detected (complete kill) SA = Sulfamate The initial titer was 8.91 logs CFU/mL. The solution pH is 8.0. The data in Table C represents log reduction.

The next set of experiments was on biofilm bacteria. This is a more challenging experiment, as biofilm are much more difficult to kill than planktonic bacteria. Again, the goal was to determine the effect of the sulfamate level on biocidal efficacy. The experiment involved a 96-well test system employing one-day-old Pseudomonas aeruginosa biofilm, and the biocidal contact time was one hour.

Please note that the P. aeruginosa strain used in the biofilm experiments is different than the strain used in the planktonic experiments. To increase the sensitivity of the experiment (minimize the difference between biocidal challenge concentrations), instead of just performing the standard serial dilution in each column of the 96-well plate, two different biocide concentrations were used and then serially diluted in each column.

Figure 3A shows there is no difference in efficacy in this test for material with any added sulfamate to solutions with up to an additional 150 ppm of sulfamate. At all levels of added sulfamate tested, the MBEC was 6 ppm.

“At short contact times, the addition of sulfamate reduces biocidal efficacy, but again, even with the addition of 100 ppm additional sulfamate, acceptable biocidal efficacy is achieved at longer contact times.� the Analyst Volume 27 Number 2

Is Overstabilization of Stabilized Bromine a Significant Concern?

continued

Figure 3: 3A (top): Effect of one-hour biocidal contact time with varying amounts of stabilizer against a one-day-old Pseudomonas aeruginosa biofilm. 3B (bottom): Cloudy wells indicate that the bacteria were not all killed by the biocide.

“The next set of experiments was on biofilm bacteria. This is a more challenging experiment, as biofilm are much more difficult to kill than planktonic bacteria.�

Samples from five cooling towers at a chemical manufacturing plant were acquired and the sulfamate level measured. These cooling towers are slug-dosed daily with stabilized bromine, and the microbial level in the cooling water is controlled to 103 to 104 CFU/mL. The cycles of concentration are approximately seven for each tower. In addition, dip slides were sent with the samples.

The dip slides confirmed that at the time the samples were taken, the bacterial load in the cooling tower water was 103 to 104 CFU/mL. The sulfamate data is shown in Table D. Table D: Summary of the Size and Sulfamate Levels in Cooling Towers From a Chemical Manufacturing Plant

Since no efficacy differences were observed at up to 150 ppm added sulfamate, higher levels of sulfamate were tested. Figure 3B shows the results of that test. In this case, clear differences in efficacy were observed. Again, the biocide with no added sulfamate had an MBEC of 6 ppm. However, the biocide with 200 and 250 ppm of added sulfamate had an MBEC of 13 ppm, and the wells with 300 ppm sulfamate had an MEC of 25 ppm.

The next component of this study was to examine realworld samples. We wanted samples from cooling towers that were using stabilized bromine as a biocide and were maintaining good microbiological control. The sulfamate levels in these cooling towers would provide us with information on sulfamate levels that can exist in cooling towers that were under microbial control.

24

Cooling Tower

Volume (gallons)

Sulfamate (ppm)

Tower A

50,000

96

Tower B

35,000

216

Tower C

45,000

19

Tower D

16,000

207

Tower E

20,000

52

The sulfamate levels show that the cooling towers are under very different loads and that they fed differing amounts of stabilized bromine. Cooling towers had more than 50 and 90 ppm sulfamate and were still under acceptable microbial control. It might have been predicted that at these sulfamate levels, the cooling towers should be overstabilized. However, these realworld examples are consistent with the biofilm and planktonic data that were generated in this study. What was a bit surprising was that for two of these cooling towers, acceptable microbial control was achieved at sulfamate levels around 200 ppm. This is a much higher sulfamate level than would have been predicted for being able to maintain microbiological control.

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Is Overstabilization of Stabilized Bromine a Significant Concern?

continued

Conclusions

The data from the planktonic bacteria testing showed that, while additional sulfamate reduced efficacy of the biocide, excellent log reductions were achieved at contact times relevant to a cooling tower, even with an excess of 100 ppm sulfamate present.

The data from the biofilm testing also showed that no change in the MBEC at up to 150 ppm added excess sulfamate.

Finally, the real-world data showed that cooling towers containing from 50 to more than 200 ppm sulfamate were still able to maintain good biological control when using stabilized bromine as the biocide.

All of this data (planktonic, biofilm, and real world) clearly shows that most of the speculation in the industry about at what sulfamate level overstabilization definitely occurs is too conservative. We suggest that there is not one particular sulfamate level above which overstabilization definitely occurs in all cooling towers. Variables like the type and amount of bacteria, organic load, presence of ammonia, and temperature will surely impact this value. Thus, the level of sulfamate that needs to be present for overstabilization to occur will depend on the conditions present in a cooling tower at a particular point in time.

Acknowledgements

The authors would like to thank Lucas Medwell for supporting this work. We would also like to thank Dr. John Power and Miguel Gutierrez for helpful discussions.

Endnote

STABROM® 909 is the stabilized bromine biocide referenced in the text that was used in the experiments. It is manufactured by Albemarle Corp.

A

Qilong Xu, Ph.D., is a senior scientist at Southern Microbiological Services, LLC. He has 20 years of experience in the fields of plant pathology, genetic engineering, medical microbiology, and food safety.

Dr. Xu’s work focuses on biofilm assay, biocide application, and viable but nonculturable bacteria. He received his doctorate in 2004 from the University of Kentucky. Dr. Xu can be reached at qilongxu@gmail.com.

Brian Nixon is a senior lab technician at Albemarle Corp. He received his B.S. in environmental science from Southeastern Louisiana University. He has 10 years of experience working in food safety and biocides. Mr. Nixon has a patent on the synthesis of a pharmaceutical active and one publication discussing viable but not culturable (VBNC) pathogens after being treated by food safety biocides. He can be reached at brian.nixon@albemarle.com.

William T. Doerrler, Ph.D., is an associate professor of biological sciences at Louisiana State University and president of Southern Microbiological Services. He has 30 years of experience in the fields of molecular biology, genetics, microbiology, and food safety. Dr. Doerrler’s current research is focused on mechanisms of bacterial resistance to antibiotics and antimicrobial peptides. He received his doctorate in 1999 from the University of Texas Southwestern Medical Center and joined the LSU faculty in 2004. Dr. Doerrler can be reached at wdoerr@lsu.edu.

Eric Liimatta, Ph.D., is a customer applications and technical support advisor for Albemarle. He has more than 20 years of experience in the biocide area.

He has 15 U.S. patents, most of which are in the area of applications of biocides for food safety. Dr. Liimatta received his doctorate in inorganic chemistry from Northwestern University in 1988 and joined Albemarle in 1989. He can be reached at eric.liimatta@albemarle.com.

This technical paper was presented at the 2019 AWT Annual Convention, which was conducted September 11–14, 2019, in Palm Springs, California.

26

the Analyst Volume 27 Number 2

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Can RO Concentrate Successfully Work as Cooling Tower Makeup?

Timothy Keister, CWT FAIC, ProChemTech International, Inc.

30

the Analyst Volume 27 Number 2

Background

Evaporative, or "wet," cooling towers are the technology of choice for commercial and industrial cooling systems, as water is the best material for both transfer of heat and evaporative cooling. Such installations are many times the largest water consumers at the facility and often account for more than 30% of total water use.

Figure 1 shows Cooling Tower #3 at the case history chemical plant.

Figure 1: Cooling Tower #3 at the case history chemical plant.

Due to freshwater shortages in many areas and increased water and sewer charges, many facilities are now looking to reuse industrial wastewaters as cooling tower makeup.

Often, facilities with cooling towers also have reverse osmosis (RO) treatment to purify incoming water for process use or boiler makeup. A typical RO unit operates at a recovery of 75%. So, for a treated permeate flow of 100 gallons per minute (gpm), the influent flow would be 133 gpm with a brine (concentrate) flow of 33 gpm.

For a cooling tower operating at 5 cycles of concentration (COC), a brine flow of 33 gpm (47,520 gallons per day [gpd]) would be sufficient to operate a cooling tower with a thermal capacity of 1,342 tons. Currently, the majority of RO installations simply discharge the brine to sanitary sewer.

If the RO influent is softened by pretreatment, the RO brine will also be low hardness with high levels of rejected ions such as sodium, chloride, and sulfate.

Looking at the brine as cooling tower blowdown at 75% recovery, the water would be at a COC of 4. While RO brine would be extremely corrosive when operated at 5 or more COC in a cooling tower, a treatment chemistry (1, 2) is available that is suitable for the operation of cooling towers using RO brine as makeup. A generic term for the chemical treatment would be “polysilicate-phosphate.”

The taught inorganic chemistry forms a corrosion-resistant layer on ferrous and yellow metal surfaces which is effective at the high pH, dissolved solids, alkalinity, chloride, and sulfate levels in the cycled cooling water when RO concentrate is the makeup water source.

Figure 2 shows a schematic of the installed system in 2017 with the RO units and the three cooling towers.

The diagram shows how the RO brine is stored in a storage tank for use in the cooling towers.

As cooling tower loads change and operation of RO systems is often on an intermittent basis, a hydraulic equalization and soft water backup system must be devised if RO brine is to be reliably reused as cooling tower makeup. A typical system would consist of a RO brine accumulation tank, level controls to add soft water when the tank level falls to a predetermined level, appropriate level alarms, and a dual pump skid to provide cooling tower makeup water. Figure 2 shows a schematic of the installed system in 2017 with the RO units and the three cooling towers. The diagram shows how the RO brine is stored in a storage tank for use in the cooling towers.

“The water management program implemented for the reuse system uses a single polysilicate-base corrosion and deposition inhibitor product and a single oxidizing biocide.”

31

the Analyst Volume 27 Number 2

Can RO Concentrate Successfully Work as Cooling Tower Makeup?

continued

Figure 2: Schematic of the 2017 installed system that shows the two RO units with the concentrate discharge to the accumulation tank.

The economics typically justify the cost of an equalization and backup system given current water and sewer rates. Using the rates from Tucson, Arizona, water at $5.88/1,000 gallons (gal) and sewer at $4.85/1,000 gal with a 100-gpm RO system operating on a 12-hour per day (h/d) 360-days per year (d/yr) basis, we see that reuse of the brine would reduce the water and sewer costs due to RO operation, shown in Examples 1 and 2: Water: 23,760 gpd Reduction = $139.71/d

Example 1

Sewer: 23,760 gpd Reduction = $115.24/d

Example 2

Examples 1 and 2 show that the use of RO would permit a total cost reduction of $254.95/d or $91,782/yr.

A daily brine flow of 23,760 gpd would be sufficient to operate a 671-ton thermal load on a 24/7 basis 360 days/ yr operating at 5 COC.

32

Considering the cost of the single equalization and backup system installed to date with capacity for a 500-ton thermal load, we estimate that a 671-ton system would cost no more than $64,000, giving a simple return on investment (ROI) of less than a year.

Case History

Here is a case history to illustrate the use of RO concentrate in a chemical manufacturing plant in Arizona.

A chemical manufacturing plant desired to reduce its use of freshwater and subsequent discharge of wastewater to the sanitary sewer. Our examination of the plant showed two RO systems operating with softened influent water to provide high-quality process water with brine discharged to the sanitary sewer. Typically, an average of 20,500 gpd of concentrate is produced by these RO systems. Three process cooling tower systems were also on site using hard city water for makeup with a designed thermal load of 500 tons. The average RO brine the Analyst Volume 27 Number 2

Can RO Concentrate Successfully Work as Cooling Tower Makeup?

continued

flowrate was determined to be sufficient to supply more than 100% of the cooling tower makeup needs under most conditions. As RO brine is concentrated soft water, corrosion in the cooling tower systems was the major concern, given the high chloride and sulfate levels in the city water supply.

Equalization and Backup Equipment

The equipment package consisted of a 5,000-gallon black polyethylene tank to receive the RO brine and a manufactured dual-pump skid to provide water to the cooling towers. The treatment system included a programmable logic controller (PLC)-based control panel with makeup and blowdown meters, soft water backup valve and water meter, overflow meter, and retrofit of the three cooling tower systems with new control A and chemical feedB units. This equipment package was installed by a combination of chemical plant personnel and an outside plumbing contractor.

Installation and startup was completed in March 2017.

Figure 3 shows the PLC control panel.

Figure 3: PLC control panel in chemical manufacturing plant.

Cooling System Information

The cooling tower systems are equipped with four counter-flow units (PVC fill)—one with galvanized steel and three with stainless steel construction. Cooling Towers #1 and #2 are connected and operated as one system in Cooling Tower #3, giving a total of three cooling tower systems. The total rated thermal capacity of the cooling tower systems was given as 500 tons, typically operating 24 hours per day, seven days a week, providing cooling water to plant chillers and air compressors. Using hard city water makeup, these cooling towers were being operated at three COC with conductivity-controlled blowdown, timed biocide addition, and makeup proportional chemical feed.

The major reason for replacing the cooling tower controllers was that the cooling towers were to be operated at more than 5 COC with the brine water as makeup, resulting in a cooling water conductivity exceeding the maximum 10,000 millimho (mmhos) range of the existing controllers.

The water management program implemented for the reuse system uses a single polysilicate-base corrosion and deposition inhibitor product and a single oxidizing biocide (n,n, dibromosulfamate [stabilized bromine]) for biological control. A colorimetric control tracer is used for routine manual control testing since discharge of the commonly used cooling water molybdate tracer to the sanitary sewer in the blowdown is not permitted.

COC are maintained between 5 and 6, based on cooling water conductivity. Note that chloride testing, often used for COC control testing, cannot be utilized because of variations in the RO brine chloride levels and use of a high-chloride content biocide.

Startup Problems

Two major problems became evident during system startup.

1. Routine testing of the water in the accumulation tank showed total hardness values from 85 to 170 milligram per liter (mg/L). Going upstream, we found total hardness values of 68 to 136 mg/L in the RO influent. Obviously, the facility had some major problems with operation, or damage to the two water softeners providing influent water to the RO units. The problem was corrected by the two outside contractors responsible for maintenance and operation of the RO systems.

33

the Analyst Volume 27 Number 2

Can RO Concentrate Successfully Work as Cooling Tower Makeup?

continued

2. A second problem became evident when we attempted to increase COC in two of the three cooling towers systems from 3 to the target of 5.

An investigation showed that the two cooling tower systems that were unable to increase to the desired COC were equipped with sidestream hydrocyclone units that purged on a time basis. The hydrocyclone units were shut down and the cooling towers COC immediately increased to the desired level. Water discharged during the hydrocyclone purge was sufficient to limit COC. We also noted that sidestream hydrocyclones are of little value on cooling tower systems because of their inability to remove particles smaller than 25 microns.

Results

The operational information shown in Table A covers the time period June 19 to July 19, 2017.

Table A: Operational Data From Cooling Towers Metered total cooling tower makeup: 446,500 gal Metered soft water backup amount: 5,000 gal Metered cooling tower blowdown: 62,500 gal Calculated evaporation: 384,000 gal Calculated thermal load: 482 tons

Table B: Analysis of Water Samples Parameter

City Water (mg/L)

RO Brine (mg/L)

CT #1 (mg/L)

CT #2 (mg/L)

CT #3 (mg/L)

pH

7.8

8.2

9.5

9.5

9.5

Total alkalinity

120

338

2,185

2,163

2,125

Conductivity

991

2,210

11,650

11,690

11,500

Calcium

76.5

0.07

0.56

0.53

0.40

Magnesium

25.4

0.068

0.375

0.304

0.339

Iron

<0.05

-

<0.03

<0.03

<0.03

Copper

<0.05

-

0.04

0.02

0.03

Zinc

<0.012

-

0.040

0.031

0.069

Silicon

3.1

32.0

105

101

100

Chloride

145

255

3,350

3,380

3,352

Sulfate

237

418

3,170

3,160

3,316

Total hardness

296

0.5

2.9

2.6

2.4

5.3

5.3

5.2

COC on conductivity

It is a rule of thumb (3) in the cooling water industry that a maximum chloride level to prevent excessive corrosion is 1,200 mg/L, while high levels of sulfate also increase corrosion rates. As shown in the analysis results, cooling water chloride levels obtained are more than twice the maximum industry rule of thumb, along with a substantial amount of sulfate also being present.

Corrosion Test Results

As a basis for comparison, the following results were calculated using the thermal load and operating the cooling systems at three COC in Equations 1 and 2: Total Cooling Tower Makeup: 576,000 gal Cooling Tower Blowdown: 192,000 gal Fresh Water Use Reduction = 576,000 gal - 5,000 gal = 571,000 gal Eq. 1 Sanitary Sewer Discharge Reduction = 638,500 gal 62,500 gal = 576,000 gal Eq. 2

Water Quality Data

Table B compares makeup and cooling tower analysis results for samples taken on July 17, 2017.

As corrosion is the major concern when operating with a cycled soft water having high levels of chloride and sulfate, the customer engaged a third party to undertake two corrosion coupon studies between June and December 2017. Cooling water parameters of conductivity, chloride, and sulfate were within the ranges noted during the entire corrosion coupon study period. Coupon material selection was by the third party with no input from the author. The results as reported are summarized in Table C. Table C: Corrosion Coupon Test Data Coupon Material

CT #1

CT #2

CT #3

Mild steel average

1.5 mils/yr

0.35 mils/yr

0.3 mils/yr

Copper average

0.1 mils/yr

<0.1 mils/yr

0.1 mil/yr

Minimal pitting corrosion was reported. These are excellent results per the Association of Water Technology (AWT) guidelines (4) for industrial cooling tower systems.

34

the Analyst Volume 27 Number 2

Can RO Concentrate Successfully Work as Cooling Tower Makeup?

Technology History

continued

The technology to use soft water makeup chemistry had its beginnings in 1984, when softened makeup water was first used to address severe scale problems in cooling tower systems providing cooling water to large, very high-temperature glass-melting furnaces. A two-furnace plant is shown in Figure 4. While use of softened makeup water eliminated the scale problem, severe corrosion problems became evident within six months.

C

Figure 4: A glass-melting plant facility with two furnaces.

makeup water. With the continuing decrease in the availability of good quality cooling tower makeup water, the ability to reuse RO concentrate as cooling tower makeup water with equal or better corrosion control is a positive environmental good. It is also a definite economic benefit to reduce utility costs by reusing RO concentrate, decreasing costs of freshwater purchase and sewerage fees. Under this approach, about 80% of the concentrate is evaporated by operation of the cooling tower, meaning there is no fee for that disposal method.

References 1. Keister; T.E. (February 21, 2008). “Operation of Evaporative Cooling Towers with Minimal or No Blowdown,” U.S. Patent No. 7,595,000.

2. Keister, T.E. (September 11, 2009). “Composition for Operation of Evaporative Cooling Towers with Minimal or No Blowdown,” U.S. Patent No. 8,128,841.

3. Frayne, C. ( January 2001). Cooling Water Treatment Principles and Practice, Chemical Publishing Co., Inc., New York, NY.

4. AWT Technical Committee (2016). “Recommendations and Guidelines for Corrosion Coupons in Cooling Systems,” Association of Water Technologies, Rockville, MD.

Endnotes A The pump skid and treatment system control panel mentioned in the text were made by ProChemTech International Inc., Brockway, PA.

Initial work discovered that a high molybdate-polysilicate-polydiol formulation provided acceptable corrosion control at moderate COC using 100% softened makeup water. A later addition of zinc to the formulation provided additional corrosion control.

With the substantial increase in the cost of molybdate and imposition of effluent limits on the discharge of molybdate in some jurisdictions, additional research and development was conducted to eliminate molybdate from the formulation. This work was successful in the discovery that addition of polyphosphate and orthophosphate as a molybdate replacement to the formulation provided acceptable corrosion rates at an economical dosage. Azole and a white rust inhibitor compound are also included in formulations for cooling systems where yellow metals and galvanized components are present.

Closing Thought

The answer to the initial question is “yes, RO concentrate can be used as cooling tower makeup.” The enabling technology is a result of research on corrosion control technology to resolve an initial problem with high corrosion rates when cooling towers were switched to softened 35

B The cooling tower control and chemical feed controllers mentioned in the article were Advantage MegaTron XS controllers, which are made by Advantage Controls in Muskogee, Oklahoma.

C Aqua-Ionic™ is the trademark for the treatment technology used when cooling towers use softened makeup water as referred to in the text. It is offered by ProChemTech International Inc., Brockway, Pennsylvania.

Timothy Keister has a B.Sc. in ceramic science from Penn State and is the chief chemist of ProChemTech International, Inc. He is a Certified Water Technologist (CWT); a fellow of the American Institute of Chemists; emeritus member of the American Institute of Chemical Engineers; and member of the WateReuse Association, the American Chemical Society, the Cooling Technology Institute, and the Water Environment Association. After 13 years in the glass industry as the water/wastewater manager responsible for 38 plants, Mr. Keister founded ProChemTech in 1987 as a water management and technology development firm. He currently has 11 water treatment technology patents. He may be reached at tek@prochemtech.com.

This technical paper was presented at the 2019 AWT Annual Convention, which was conducted September 11–14, 2019, in Palm Springs, California.

the Analyst Volume 27 Number 2

Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants: An ASME Research Report Edward S. Beardwood, Solenis LLC

36

the Analyst Volume 27 Number 2

Abstract

The Combined-Cycle Task Group for the Water Technology Subcommittee of the ASME Research and Technology Committee on Water and Steam in Thermal Systems has prepared a 90-page report regarding pre-commissioning (1), which is now available to the public. This article introduces the elements of the consensus report and highlights some of its features.

The document provides guidance on design, procurement, and pre-commissioning activities that will result

in the construction of a plant with steam/water-wetted surfaces that are as clean and corrosion-free as practical. Issues can surface during the commissioning of a combined-cycle power plant (see Figure 1) that cause unintended delays, cost overruns, increased post startup maintenance, and depreciation of equipment. Consensus recommendations have been developed to minimize these risks and improve long-term reliability. The material contained in the document is also transportable and transferable to other steam generation systems.

Figure 1: Combined-cycle power plant layout.

â&#x20AC;&#x153;Examples of design phase improvements are the inclusion of condensate polishers for startups and condenser leaks and equipment design upgrades.â&#x20AC;?

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the Analyst Volume 27 Number 2

Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

Introduction

The time required to commission a combined-cycle power plant can vary substantially and affect the overall cost of the project prior to commercialization. A number of pre-commissioning delays have been experienced in the independent power-producing industry that is associated with the critical path of these projects. In some cases, important issues are overlooked or compromised in order to move to the next segment of the pre-commissioning. Shortcuts taken at various stages of the project, such as not chemically cleaning the unit, can threaten the integrity of the equipment and/or delay the project’s completion. One survey of combined cycle pre-commissioning experiences revealed that four out of 22 performance issues accounted for 77% of the concerns. These included: Improper use of, or ignoring, standard practices and procedures, 27%.

Insufficient staff to accomplish the work in the scheduled timeframe, 22%.

Poor project planning, 16%.

Breakdown in communication among project team members, 12%.

It is critical that the availability and conditioning of the water to be used for plant processes be well understood in the design stage of the project. The duration of the project commissioning process and the long-term reliability of the equipment can be affected by the ability to supply or produce water of the required quantity, quality, or purity. Therefore, the production of high-purity water and the associated treatment issues must be considered part of the critical path. The chemistry criteria required to establish and maintain internal surface cleanliness during all stages of the project must not be overlooked.

The Engineering, Procurement, and Construction (EPC) contractor’s technical team should be involved in all phases of design specification development prior to the release of the RFQs (Request for Quotations). EPC contractors can employ the techniques specified herein to ensure the chemistry requirements and limits are met during commissioning and through initial start-up operations. Operating for significant periods of time outside 38

the chemistry limits imposed by heat recovery steam generator (HRSG) and turbine manufacturers will void the manufacturer’s warranty. This will leave the owner/ EPC contractor liable for the full cost of any repair that may be required within the warranty period.

During the plant design phase, it may be beneficial and cost effective to consider additional equipment or modifications to equipment designs, which could significantly reduce the cost and duration of the startup process, even at the expense of increased capital cost. Post startup operating problems and plant component failures may also be avoided long term. Examples of design phase improvements are the inclusion of condensate polishers for startups and condenser leaks and equipment design upgrades for cycling operations.

Experience has shown that failure to consider complex interrelationships between the various component systems can result in costly delays in project completion and turnover dates. Additionally, incorrect procedures and planning can result in damage or failure of key pieces of equipment or systems during subsequent operations. An example of recommendations is illustrated in this article’s Appendix A: “Avoiding Premature Failures.” Other procedures are provided throughout the document that will be useful for those involved in the design, construction, and commissioning of a combinedcycle power plant, with or without export steam.

A generalized representation of the timeline for a combined-cycle plant development, construction, and commissioning timeline is given in Figure 2. While this document primarily addresses the physical pre-commissioning stages, design specifications are also very important, and equipment selection determines the available cycle chemistry options. These concerns are discussed in the document and referenced to related literature sources. Influent water quality, treatment, and the resultant water purity are important parts of design and pre-commissioning. Poor equipment cleanliness and improper water chemistry have been responsible for costly delays and corrosion-related failures. Notes for the segments in Figure 2 are listed in Table A.

the Analyst Volume 27 Number 2

Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

Figure 2: Combined-cycle plant development, construction, and commissioning timeline.

Table A: Associated Notes for Work Segments of the Commissioning Timeline Work Segment

Notes Regarding the Work Timing

A

Business/project development may take six months to two years to establish contracts and obtain permits.

B

Development of design specifications begins during Segment A.

C/D

Construction can start as early as six months into the design specifications segment with land grading and initiation of support pilings and structures. About 18 to 24 months total time is required for this segment.

E

Makeup water treatment plant startup will take approximately one week. Temporary piping and exhaust points for the steam blow are typically installed concurrently with this segment.

F

Initial hydro and feedwater train cleaning and operational startup requires about four days to one week.

G

Hydraulically flushing and chemically cleaning the HRSG requires about one week; however, up to 30 days has been reported.

H

Steam blows, depending upon the number of flow paths chosen and the impingement target acceptance criteria, can take from two to three days.

I

Turbine startup. The time, which includes dismantling the temporary piping and refitting the steam turbine (ST) to accept steam plus debugging turbine controls, will vary and may take five to six weeks.

J

Baseline run/performance testing will require 100 hours of continuous run. Total time will vary.

K

Cycle transition. Approximately one to two years are typically required to complete all the outstanding issues.

Project Development and Design Considerations

It is impossible to define a template for typical project development as no two prospective power plant sites will be the same. Generally, the initial project development tasks include: 1. choice of a suitable site with access to water, transmission lines, and fuel; 2. definition of the type of operational duty required; and 3. evaluation of project economics and permitting requirements. Project development considerations are illustrated in Figure 3. The size of the plant and whether or not it includes export steam with or without condensate returns must be defined. The HRSG, gas turbine, and steam turbine can then be configured appropriately.

39

The main decision drivers during project development are the type of plant, available water supply, environmental considerations, chemical regimes, and major equipment components (i.e., HRSG, condenser, steam turbine, and water treatment equipment). Determining the way the plant will be operated early in the project development is important. Deciding whether or not a plant will normally be base-loaded or cycling is an important decision that can then be incorporated into the plant design. Base-loaded plants are designed to operate at full load, or at a steady base load, the majority of the time. Cycling units may operate anywhere from no load to full load at any time and are frequently shut down or bottled up during the nighttime and weekends.

the Analyst Volume 27 Number 2

Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

â&#x20AC;&#x153;Determining the way the plant will be operated early in the project development is important.â&#x20AC;?

Figure 3: Project development considerations.

If the plant is to operate routinely in a cycling mode, the anticipated frequency and duration of the cycles must be addressed in the plant design phase. Under cycling conditions, the expansion and contraction rates of critical components such as hangers, joints, piping, duct work, coils, tubes, and tube-to-tube header connections must be included in the design to avoid low-cycle thermal fatigue failures. Specifying a design to include cycling will affect startup ramp rates and possibly the details of construction of the equipment. Some of the items that must be designed to accommodate operation not only for normal or base-loaded operation conditions, but also for frequent start-up operations, include the chemical feed system, makeup water treatment system, HRSG blowdown system, drain line locations, drain pots for condensation with conductivity sensors, stack dampers, and insulation. When the deaerator and/or steam turbine condenser are not in service, auxiliary steam availability 40

and a correctly sized steam sparge in the demineralized water storage tank and condenser hot well should be present to provide warm startup conditions and some deoxygenation.

If the plant is to supply steam to an outside host, additional preplanning during the project design and development phase can minimize problems during plant startup and operation. Items that should be addressed in the design of a cogeneration facility include host steam chemistry limitations, collection and treatment of the returned condensate, chemistry limits for acceptance of returned condensate, sizing of the makeup treatment system to replace dumped condensate, disposition of dumped condensate, and operation without steam export.

Critical parameters for the design of a combined-cycle power plant are itemized in Table B. the Analyst Volume 27 Number 2

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Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

Design Parameters

Table B: Critical Design Parameters 1. Steam Host or Stand-Alone

a) Requirements for and restrictions on host steam purity

b) Condensate—amount and quality recovered versus

returned purity required 2. Climate/Weather/Location of Plant

a) Equipment redundancy

b) Freeze protection

c) Shipping/procurement time for equipment and chemicals 3. Gross Rating

a) Power augmentation that will be applied

b) Secondary fuel type that will be used 4. Operation Mode; Base-Load or Cycling

a) Manpower requirement

1. Degree of automation

2. Instrumentation

3. Maintenance requirements

b) Ramp rates allowed (environmental—air permit) 5. Water Source and History

a) Amount required versus availability b) Chemistry

c) Review of possible treatment options

1. Reliability

2. Life cycle (maintenance/replacement costs)

d) Amount and quality of condensate from host 6. Water Balance 7. Heat Balance

a) Condenser cooling water supply 8. Discharge Permit or Zero Liquid Discharge 9. Cycle Chemistry Desired, Required, and Selected

a) Customer preferences/requirements

b) Condensate polishing required? Type selected?

10. Materials Selection for Equipment and Piping 11. Major Equipment Specification

a) Gas and steam turbines

b) Condenser—cooling tower, air-cooled, or wet-surface air-cooled c) HRSG

d) Feed pumps 12. Auxiliary Equipment Specification a) Deaerator

b) Makeup/pretreatment

c) Sampling/monitoring panels

d) Condensate polishing

e) Auxiliary boiler/steam supply

f) Chemical feed equipment 13. Cleanliness of Major Equipment Fabrication

a) Hydro testing, cleaning, and passivation requirements

b) Inspection (NDE)

c) Preservation for shop storage and transportation 14. Site Storage/Construction a) Cleanliness

b) Preservation of fabricated equipment and components c) Size and installation of hydro testing drains, connections for chemical feed, connections for chemical cleaning, and temporary recirculation system steam lines and mufflers for steam blows 15. Pre-commissioning/Startup

a) Plan adequate time and water resources for pre commissioning and startup activity

42

Water supply source. A project cannot be developed without an adequate and reliable water supply that is also economically and environmentally viable. Several potential water sources may be available when developing, planning, and executing power projects, such as city water (potable water), surface water (e.g., river, lake), seawater, well water, and gray water (secondary treatment effluent). In addition, returned condensate from one or more host facilities may be fed back into the system.

The quantity of returned condensate can vary from 0% to 90% of the total makeup water requirement and have wide variations in temperature and purity.

Once the water source is established, developing the design basis water analysis is the next major challenge.

Average and worst-case percent makeup and percent condensate return to the HRSG feedwater should be assessed. Collection of multiple samples of the raw water and host condensate return if present should be completed over an extended period of time to capture seasonal and other variations in water quality. The parameters prescribed for the different water sources and sampling frequency are summarized in Table 3 of the ASME document (1).

Water treatment equipment. Makeup water treatment systems typically consist of two subsystems: a pretreatment system followed by a demineralization system.

Selection of the pretreatment system equipment depends on the quality and source of raw water and the equipment specified for the demineralization system. The type of demineralization system is chosen to meet the final water quality needed to meet the steam and gas turbine steam purity requirements. Various water pretreatment methods and their impurity reduction capabilities are provided in Table 4 of the ASME document. All the factors needed to evaluate which pretreatment components and what type and configuration of demineralizers are required to meet purity are also discussed in the ASME document. An example of pretreatment equipment staging is illustrated in Figure 4.

the Analyst Volume 27 Number 2

Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

Figure 4: Example of pretreatment equipment staging.

Equipment size and effluent quality. The pretreatment system at a combined-cycle plant may be designed with a much larger capacity than the demineralization system to provide pretreated water for other uses, such as cooling tower makeup, service water, and auxiliary cooling water and, at some facilities, potable water.

The demineralized water makeup rate can vary from 1% to 5% of the steaming capacity for stand-alone combined-cycle power plants to more than 50% for cogeneration facilities. For multi-stage demineralization systems, the typical demineralized effluent quality should be <10 parts per billion (ppb) of silica as SiO2, <0.1 microsiemens per centimeter (µS/cm) specific conductivity at 25 °C, and <200 ppb of total organic carbon (TOC). If the makeup water treatment system is not providing the expected effluent quality, this indicates a problem that should be resolved.

Makeup water quality parameters are established to ensure compliance with main and reheat steam purity 46

limits. Other limits are then back-calculated to determine saturated steam purity limits, HRSG water limits, feedwater limits, condensate limits, and makeup water quality limits, as noted here: The saturated steam purity limits can be estimated based on the main steam limits and the attemperation rates (% of feedwater sprayed into steam).

The HRSG water limits generally are determined by the operating pressure and type of treatment (e.g., all-volatile treatment, phosphate treatment).

Feedwater quality is determined by the HRSG drum water as well as the HRSG drum blowdown rate.

The makeup water quality requirements are based on HRSG feedwater quality and condensate return.

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Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

historical makeup and condensate return data to improve makeup water treatment equipment selection, sizing, and regeneration sequencing.

Condensate polishers. Condensate polishers are resinbased systems used to remove contaminants from the HRSG feedwater cycle. There are several plant design situations in which condensate polishers should be included as part of the condensate/feedwater system design. These are: Plants where brackish water or seawater is used to cool the main condenser.

Plants where condensate from exported steam is returned to a steam cycle operating above 1,200 pounds per square inch gauge (psig) (8.27 megapascal [MPa]).

Plants with a steam cation conductivity limit < 0.15 µS/cm.

Condensate polishers are also recommended for plants that are designed with two or more of these six design and operating characteristics which have the potential to impact plant performance and startup: Plants with steam cation conductivity limits < 0.20 µS/cm.

Plants where an air-cooled condenser (ACC) is used to cool steam turbine exhaust.

wise investment. Polishers can reduce the time required to obtain steam purity during plant startup, allow the unit to operate for a limited time with a condenser leak, allow for an orderly shutdown of the unit if a condenser leak occurs, reduce the requirement for demineralized water makeup by decreasing steam cycle blowdown requirements, and provide savings associated with the cost of demineralized water.

If condensate polishing equipment is not installed, rental ion exchange systems, designed as part of a sidestream cleanup loop, can be used after the steam blows to facilitate faster cleanup. Connections for this equipment must be planned in advance.

Steam and gas turbines. Specifications for steam turbines (see Figure 5) are typically performance based.

Therefore, it is essential to coordinate and lock in the plant design water and heat balances for the steam turbine, gas turbine, and HRSG suppliers as early in the project development phase as possible. A single plant design water/heat balance is not sufficient. Multiple potential operating conditions need to be evaluated based on different anticipated plant scenarios, such as fogging, power augmentation, and attemperation. In particular, if equipped with duct burners, the plant heat balance during duct burner operation needs to be addressed. The worst-case scenario should then be used to back-calculate the water quality required to meet the specified operating limits for sodium, potassium, silica, chloride, sulfate, phosphate, and TOC. Figure 5: Cut away of a steam turbine.

Plants that operate with an all-volatile treatment (AVT) or oxygenated treatment (OT) chemistry program.

Plants with high-pressure (HP) steam operating pressure greater than 2,400 psig (16.55 MPa).

Cycling units with short startup times.

Plants with a steam turbine manufacturer limit on low-pressure (LP) steam cation conductivity included in contract.

Even if the plant does not operate with any of these waters or conditions, condensate polishers may still be a 48

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Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

â&#x20AC;&#x153;Operational control ranges can then be established for water conditioning equipment, drum chemistry, and steam purity. With this information in place, the preferred water treatment chemistry regime can be selected.â&#x20AC;?

For steam purity, this calculation will include the impurities in the drum water that are transported by both mechanical carryover (pressure dependency chart) and vaporous carryover (impurity distribution ratio at various pressures), plus the contribution of any attemperation water. Based on these calculations, the makeup treatment and condensate polishing equipment can be configured and sized. Operational control ranges can then be established for water conditioning equipment, drum chemistry, and steam purity. With this information in place, the preferred water treatment chemistry regime can be selected, taking into account operational flexibility and provisions for modification during incidents such as condenser in-leakage, condensate contamination, or chemical pretreatment upsets. Refer to Figure 6 for additional guidance.

Figure 6: Chemical treatment regimes.

Turbine steam purity limits are the basis for most other steam cycle-related equipment design, selection, and operational control limits. When the gas turbine (see Figure 7) design includes steam injection or cooling, the steam turbine steam purity requirements need to be compared to the steam purity requirements for the gas turbine. Then, using the more restrictive requirements, the plant designer should determine the required makeup treatment system water quality parameters and the permissible cycle chemical treatment regimes.

50

the Analyst Volume 27 Number 2

Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

configuration within the condenser (i.e., full width of the condenser, with sparger tubes perpendicular to the condenser tubes and the sparger jets from the sparger tube parallel to the condenser tubes).

Figure 7: Cut away of a steam turbine.

Matching gas turbine and steam turbine cycles during transients and low-load conditions is difficult. The greatest difficulty is experienced during startups, shutdowns, and steam turbine trips. Because the gas turbine produces so much exhaust heat at such a rapid rate the thermal ramp rate limits, as well as the permissible metal-to-steam temperature gradients (i.e., ∆T = 145 to 200 °F/hour (h) or 63 to 93 °C/h), are often violated in thick-walled components of the HRSG and/or steam turbine during these transients.

Controlling these variables can require special gas turbine firing controls, a flue gas bypass stack and damper, and/or a steam turbine bypass system/dump condenser. The latter can be accomplished in either a cascading or parallel fashion, but the former is more desirable. Sizing the dump system typically requires consideration that 140% of the steam turbine’s 100% load is ejected during a trip. Therefore, sizing of valves, piping, and dump tubes (spargers in the condenser) is very important, as is control of attemperation of the high-pressure bypass steam and reheat bypass steam.

Feed-forward schemes are typically used where the pressure and temperature upstream of the pressure control valve (PCV) and pressure downstream of the PCV are measured. The attemperation water flow is then handled based on the enthalpy and mass flowrate of the dump steam during the transient, decreasing component failures associated with excessive superheat steam temperature. Erosion and vibration are handled by line/ valve/sparger sizing and sparger system location and 52

Chemical regimes. Phosphate treatment is most often used when HRSGs send steam to and receive condensate back from a host plant. The process of selecting the chemical treatment program for the HP evaporator should include consideration of many plant parameters, including steam purity requirements, type of makeup water treatment, presence and type of condensate polishers, potential for condensate contamination, condensate and feedwater system metallurgy, HRSG design, operating pressure, the use of duct burners, cycling service, and the availability of a chemist to quickly implement corrective action, should it be required. A decision tree for chemical treatment selection is illustrated in Figure 3, which presents some of the factors to be considered when selecting the HP evaporator chemical treatment regime.

The chemical treatment regimes shown in Figure 3 are as follows: All-volatile treatment (AVT) Alkaline phosphate treatment (APT) Caustic treatment (CT) Congruent phosphate treatment (CPT) Oxygenated treatment (OT) Once all water-conditioning equipment and chemical treatment programs are selected and test control ranges and action levels established, analytical testing and monitoring equipment, as well as the sampling locations and sample conditioning methods, can be selected.

Guidance on operational chemistry control limits can be found in the ASME publication Consensus on Operating Practices for the Control of Water and Steam Chemistry in Combined-Cycle and Cogeneration Power Plants (2).

The associated sampling and monitoring required for chemistry control can be found in the ASME publication Consensus on Operating Practices for the Sampling and Monitoring of Feedwater and Boiler Water Chemistry in the Analyst Volume 27 Number 2

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Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

Modern Industrial Boilers (3). The design specifications and baseline calculations found in the above referenced ASME publications are used in the pre-planning for both the pre-commissioning and the commissioning phases of the combined-cycle plant.

HRSGs. Stand-alone deaerators typically provide additional flexibility in selection of the chemical treatment program for the LP evaporator. The use of an integral deaerator limits the chemical treatment program to AVT and requires specifying upgraded materials for this section of the HRSG to prevent FAC issues. If the LP drum is utilized as a feedwater storage tank or serves as the source of attemperation water, however, AVT chemistry must be used as the treatment program for the LP section.

Additionally, the system metallurgy should ideally be copper-free, since this increases chemical treatment options for the system.

Specifications for the HRSG should define: Where (what location) the HRSG will be fabricated.

Degreasing of the HRSG by the fabricator, followed by full cleaning and passivation.

After shop hydro where the components are drained, air blown dry to a relative humidity end point of 35% or a vapor phase corrosion inhibitor (VPCI) applied, and immediately followed by sealing the equipment for delivery.

What parts, ancillary equipment, and consumables may be used? And, a preferred list of suppliers/vendors.

Auxiliary boiler emissions from an auxiliary boiler typically need to be accounted for in the application for the air permits. Therefore, the decision to use an auxiliary boiler as a permanent part of the overall plant design, or to facilitate initial plant startup, needs to be made early in the project development phase. If the plant is designed to cycle frequently, the installation of a permanent auxiliary boiler is recommended. The auxiliary boiler will allow the plant to hold vacuum overnight, speeding up the return to base load conditions in the morning and avoiding destabilization of system chemistry resulting from air 54

ingress. If you do not break vacuum, then there is a short hold time before allowing the steam to go to the turbine.

This is because air ingress causes pH depression and flash rusting of moist surfaces. Without vacuum, the time to achieve a deep vacuum and remove the noncondensable/ heat-transfer insulating gases and corrosion products is quite lengthy. Such lengthy restarts are expensive, as water, chemicals, and fuel are consumed with no steam turbine power generation. In colder climates, an auxiliary boiler is necessary to ensure that equipment does not freeze during an unscheduled outage.

Zero liquid discharge (ZLD) system. Designing a facility for ZLD has become a common occurrence for power plant developers. ZLD allows developers to site a plant in a remote area where no viable discharge option exists (e.g., river, municipal treatment facility) but a source of water is available. An important item to be addressed when designing a plant for ZLD is what to do with the wastewater when problems with ZLD equipment occur. Typically, it is financially impractical to design 100 percent redundancy into the ZLD system.

Therefore, plant developers must provide an alternate means of dealing with wastewater when equipment maintenance or replacement is required. Unless an emergency wastewater discharge location is available, it is recommended that a storage tank or wastewater pond be included in the plant design and be sized to hold a minimum of 48 hours of wastewater to deal with these situations. The ZLD system should then be sized to empty this emergency reservoir in a reasonable period of time without hindering normal full-load operation.

Miscellaneous design detail considerations. A number of bulleted items are also listed at the end of this section in the ASME document. To name a few, they include: Makeup water must be available for hydro testing, cleaning, flushing, steam blows, and performance testing. Makeup water quality specifications are provided in Table 5 in the ASME document. The quality of first fill water should be the same as that required for the HRSG during performance testing in order to minimize the likelihood of delays during testing.

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condenser hotwell when high-volume water usage rates are scheduled.

and chemical cleaning pathways, chemical injection, and sampling.

Steam from an auxiliary boiler or a rental boiler, together with steam injection lines and mufflers sized to effectively preheat the high-purity water storage tanks to a sustainable 180 °F, will be required during the steam blow process.

Condensate and temporary pumps.

Other pre-commissioning considerations. The ASME document provides further guidance and recommendations for the EPC and owner to consider during the build and pre-commissioning of the combined-cycle power plant. A brief summary of such sections are given here.

Sufficient hydro and flush water inventory and quality (see Tables 5 and 6 in the ASME document).

Section 6: “Off-Site Fabrication and Assembly.” Preferred hydrostatic test chemistry and method provided to also incorporate vapor-phase corrosion inhibitor prior to capping and sealing fabricated parts for transportation and storage.

Section 7: “On-site Construction.” Receiving and receipt of site materials, maintaining cleanliness, storage, when to unwrap and inspect, integrity of site transport lines.

Other considerations for site construction and commissioning readiness such as scheduling, connections, inspections, cleaning, and passivating.

Section 8: “Make-Up Water Treatment Plant Start-Up.” Outlines inspections, incomplete items, and deficiency list production. Clean and flush all containers, operating vessels, transfer/transport lines, and sampling lines. Verify resin volumes and operational flows during regeneration and the leakage present compared to specification.

A temporary tank fitted with full-flow filtration equipment to collect and filter the flush waters prior to return to the condenser hotwell.

Section 10: “Heat Recovery Steam Generator Cleaning.”

Describes inspections and defines preoperational cleaning methods for the type of materials and debris present. Alkaline degreasing boilout and chemical cleaning and passivation procedures are outlined as well as post-cleaning inspections and cleaning waste disposal.

The startup of the chemical monitoring and control systems is also discussed. An example of a sampling and monitoring system is illustrated in Figure 8.

Figure 8: Example of sampling and monitoring panel.

Planned flush and chemical cleaning paths, including system isolation valves or pipe blanks.

Section 11: “Steam Blows.” Both the procedure and targets for acceptable steam blow performance are discussed.

The calculation for the cleaning force ratio (CFR) target using the steam mass flow and specific volume is provided. Other important considerations for steam include provision for temporary high-volume feeding of chemicals to storage tanks, surge tanks, and condenser hot well. Steam injection mufflers and supply lines should be sized to preheat the high-purity water storage tanks to a sustainable 180 °F (82 °C) during the steam blow process.

All permanent and temporary connections, piping, and correctly sized valves to permit isolation of the flush

Section 12: “Turbine.” After the steam blows and removal of all temporary piping, the turbine will undergo

Section 9: “Initial Hydrostatic Test and High Velocity Flush.”

Water quality to be used is defined as well as the flush procedures, velocity, and final quality (i.e., <10 parts per million [ppm] suspended solids). Prior to the hydro, the following items should be functional:

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readiness for testing by the manufacturer. At this time, the calculations for steam purity, feedwater, and pretreatment control limits should be revisited. This review will allow early identification and correction of steam purity and water quality issues prior to performance testing and help minimize the potential for prolonged delays.

By this time, all plant systems should be complete and available. If permanent in-line condensate polishers are not provided, the installation and use of temporary precoat filters with deep-bed, mixed resin demineralizers installed in a side stream around the hotwell will reduce system cleanup time prior to baseline and performance testing. This practice is encouraged, particularly for plants with air-cooled condensers, because steam blow cleanup performance is highly variable. All the sampling lines and in-line instrumentation must be working and calibrated with the delay time response verified for the appropriate sampling flowrates. All predetermined chemistry and chemical treatment control ranges for achieving the desired water and steam purity levels should then be verified while initiating the system cycle cleanup prior to baseline testing.

should be achieved in no longer than three to seven days.

Longer time requirements for this activity are typically associated with poor pre-cleaning of system circuits, in-leakage problems, or the failure to use a properly designed and operated condensate polishing system.

It has been demonstrated during numerous startups that initial operation of the turbine at full load will remove impurities hidden in the steam turbine and the HRSG feedwater systems. During full-load operation, these contaminants dilute out and uniformly mix within the feedwater and condensate systems. This cleanup approach is more effective than blowdown holds since the continuous blowdown systems are only sized for 2% to 4% maximum continuous rating (MCR) flow. Therefore, the quicker that turbine full load can be reached, the sooner the target feedwater chemistry and steam purity values may be achieved. It is in the best interest of the owner/contractor to negotiate relaxation of chemistry limits during equipment contract negotiations in order to avoid long holds and costly delays, particularly when steam is first admitted to the turbine. A recommended approach is to specify that contaminant concentrations in the first steam entering the turbine not exceed four times the normal operating limits; these levels should be roughly equal to the steam turbine OEM’s Action Level 3 category. The contamination constituent limits should be trending downward before steam is admitted to the turbine and the recommended normal limits are to be met within the negotiated timeframe. Normal feedwater, HRSG, and steam chemistry limits and specifications

Section 14: “Start-Up, Shut Down, and Lay-Up.” Avoidance of cyclic stresses upon startup and shutdowns are discussed to prevent fatigue cracking. Generalized lay-up categories and procedures are also provided.

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Section 13: “Turbine Commissioning.” Initial startup feedwater chemistry guidelines and steam purity limits (values trending downwards) allowed for steam admission to the turbine are provided as well as steam turbine commissioning procedures.

Initial startup feedwater chemistry guidelines and steam purity limits (values trending downwards) allowed for steam turbine admission are provided as well as steam turbine commissioning procedures. A list of items requiring completion prior to the commercial acceptance test initiation is provided to avoid lengthy delays.

Checking and reverifying steam purity and deaeration air in-leakage performance as well as determining the phosphate (if in use) hide-out concentration at the MCR should also be done at this time.

Acknowledgements

This article is dedicated to the late Michael Rootham, a valued member of the ASME Water Technologies Subcommittee and a contributor to this consensus.

His friendship, humor, wit, intellect, and courage will never be forgotten. Also, special thanks to the reviewers and editors: Colleen Scholl, Deborah Bloom, and Anton Banweg. We would also like to thank the other 24 contributing Water Technologies Subcommittee members that assisted in the document production.

References 1. ASME (2017). “Consensus on Pre-Commissioning Stages for Cogeneration and Combined Cycle Power Plants”, Book No.: 861264, ISBN: 978-0-7918-6126-4, American Society of Mechanical Engineers (ASME), New York, NY (www.asme.org).

2. ASME (2012). “Consensus on Operating Practices for the Control of Water and Steam Chemistry in Combined Cycle and Cogeneration Power Plants”, ASME, New York, NY (www.asme.org).

3. ASME (2006). “Consensus on Operating Practices for the Sampling and Monitoring of Feedwater and Boiler Water Chemistry in Modern Industrial Boilers”, CRTD-81, ASME, New York, NY (www.asme.org).

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Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

Edward S. (Ted) Beardwood is the founder of BC&T Inc. (Beardwood Consulting & Technologies Inc.) and has more than 43 years of experience in water treatment. Before starting BC&T, his career included technical and sales positions with major specialty chemical companies, including serving as the senior global applications consultant for Solenis LLC, technical director for the Canadian operations of the Ashland Water Technologies Division, and sales representative and area sales manager for the Dearborn Division of WR Grace (now Betz/ GE/Suez). His experience in the industrial water conditioning industry has ranged from full service, sales, sales management, new construction and commissioning of thermal systems, laboratory management, regulatory compliance, product management, R&D, and consulting. Mr. Beardwood is a past chair of Water Technologies and the Research and Technology Committee for Water and Steam in Thermal Systems for the American Society of Mechanical Engineers (ASME), as well as a former working member of PTC–31 Performance Test Code for High Purity Water Systems and past chair of NACE International Research Committee STG 11 on Water. Mr. Beardwood holds 13 patents. He may be contacted at ebeardwood@bctinc.org.

This paper was originally presented at the International Water Conference, which was conducted November 13–15, 2017, in Orlando, Florida. More information about the IWC and technical papers is available at www.eswp.com/water.

Appendix A Avoiding Premature Failures

The potential for component failures may increase due to poor pre-planning, improper selection and execution of design specifications, or inadequately performed pre-commissioning stages. The nature of these failures may be mechanical, operational, or chemical.

Maintaining and monitoring cleanliness during fabrication, shipping, site storage, field construction, and pre-commissioning cleaning will avoid lengthy startup delays and post-commissioning failures.

Avoidance of premature failure is best realized by a cause-and-effect discussion regarding the most common failures experienced in a combined-cycle plant. These failures may result from, but not be limited to, any of the following categories:

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1. Construction issues, including fabrication, shop hydro, shipment, storage, and erection associated with: • Pitting corrosion • General corrosion • Microbiologically influenced corrosion (MIC) • Deposit formation • Contamination by chemicals and foreign materials 2. Preoperational issues, including hydro test, storage, chemical cleaning, steam blow, and lay-up associated with: • Pitting corrosion • General corrosion • MIC • Deposit formation 3. Design and operational issues associated with: • Flow accelerated corrosion (FAC) (both singleand two-phase flow) • Corrosion fatigue • Under-deposit corrosion • Hydrogen damage • Caustic gouging • Phosphate gouging • Pitting corrosion • Stress-assisted corrosion • Thermal fatigue • Creep • High-cycle fatigue • Fretting corrosion • Crevice corrosion • Copper alloy related corrosion mechanisms (e.g., ammonia grooving, dealloying) • MIC • Galvanic corrosion Component failures associated with poorly planned or executed design decisions and pre-commissioning activities can have a long-term impact or influence on operational failures. Several examples are provided here to illustrate their importance.

Poor pre-cleaning, drainage, and preservation of fabricated components after shop hydro testing (Category 1 in Table 1 of the actual ASME document) may result in localized general corrosion that can the Analyst Volume 27 Number 2

Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

continue during the pre-commissioning period (Category 2 in Table 1 of the actual ASME document) and manifest itself after turnover to the plant owner as high-pressure evaporator tube failures due to pitting, under-deposit corrosion, stress assisted corrosion, or, at a cyclic plant, corrosion fatigue.

Porous corrosion deposits may develop during onsite storage and erection in uncapped or unsheltered tube sections exposed to high humidity or condensing moisture. Formation of these corrosion products can be avoided by excluding moisture or by applying preservatives or VPCIs. Tube failures associated with under-deposit corrosion can result if deposits are not detected (e.g., by a video probe inspection) and removed by effective chemical cleaning prior to operation.

Greater attention to design and materials selection is required for a cycling plant. Evaluation of the potential number of restarts per year, duration of dispatch, and the time available for return to service may justify the inclusion of additional equipment, such as an auxiliary boiler to minimize susceptibility to stress assisted corrosion. In addition, corrosion fatigue failures may develop if high ramp rates are used frequently during startup. Designing the system with all-ferrous metallurgy removes concerns associated with copper/ copper alloy corrosion and permits optimization of corrosion control for ferrous materials by allowing operation at higher pH and dissolved oxygen concentrations, minimizing the susceptibility to FAC. The potential for crevice corrosion should be evaluated for all condensers with austenitic (300 series) stainless steel tubes. The Nickel Development Institute (NiDI) offers free software for evaluating the likelihood of crevice corrosion occurring in austenitic, duplex, and some other specialty stainless steels. The most significant factors contributing to crevice corrosion include low molybdenum content, pH, and sulfate concentration; high temperature; and chloride concentration. A main condenser used as a dump condenser can be particularly susceptible to crevice corrosion because of the exposure to high temperatures when steam is being dumped. The NiDI crevice corrosion model has been used to justify the installation of a more corrosion-resistant alloy (i.e., 60

a tube alloy containing a higher concentration of molybdenum), the installation of titanium tubing, and the implementation of more stringent water chemistry control limits.

Potential damage mechanisms and commonly associated locations are given in Table 1 in the actual ASME document and intentionally left out of this article due to size and complexity. Definitions of these mechanisms are included in Appendix B. When these mechanisms are initiated prior to commercial operation, degradation can be expected to continue when the plant is operational, resulting in failure at a later date.

Appendix B Damage/Corrosion Mechanisms The following terms that are associated with corrosion damage are defined based on the original ASME document (1) that this article summarizes.

Caustic gouging: The dissolution of carbon steel by localized high concentrations of sodium hydroxide.

This high-pH condition solubilizes the steel’s protective magnetite layer and ultimately forms sodium ferroite (NaFeO2) and sodium ferroate (Na 2FeO2). In-situ corrosion products remain in place, and smoothed surfaces are typically present below the deposits in the attacked area.

Corrosion: Degradation of a material and its properties resulting from chemical or electrochemical reactions within the environment.

Corrosion fatigue: Life reduction due to the occurrence of cyclic applied stress (fatigue) in a corrosive environment.

Component lifetime under corrosion fatigue is less than if fatigue life and corrosion life had both been assessed separately because of continuous breaking of the protective oxide film by fatigue action.

Creep: The time-dependent, thermally assisted deformation or strain of components under load (stress). Creep damage in a given material is a function of a combination of time, temperature, and stress and results from a combination of high stress and high temperature relative to a material’s creep limits. Damage occurs in three stages. Visible damage is induced during the tertiary the Analyst Volume 27 Number 2

Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

stage. Isolated creep microvoids coalesce along grain or dendrite boundaries, resulting in fissure formation prior to stress rupture.

Crevice corrosion: Localized corrosion resulting from the formation of a concentration cell in a crevice formed between two surfaces that shield it from the full oxygen content of the environment.

Fatigue: Repeated applied stress cycles that result in reduction of strength, crack initiation, and crack propagation. Most of a componentâ&#x20AC;&#x2122;s fatigue life occurs prior to crack initiation. Crack morphology varies based on type of fatigue loading (i.e., high-cycle, which typically is induced by vibration, or low-cycle, which is typically induced thermally) and environment (e.g., corrosion fatigue cracks often are oxide-filled and produce secondary parallel cracks).

Flow-accelerated corrosion (FAC): FAC is a phenomenon that affects the normally protective oxide layer formed on carbon or low-alloy steel. With FAC, the oxide layer dissolves into the flowing stream of water or a watersteam mixture. As the oxide layer becomes thinner and less protective, the corrosion rate increases. Eventually a steady state is reached where the oxide dissolution rate equals the oxidation rate, and no oxide exits on the metal to slow corrosion. It is important to note that in the FAC process, the protective oxide film is not mechanically removed. Rather, the oxide is dissolved. Thus, FAC may be defined as corrosion enhanced by mass transfer between a dissolving oxide film and a flowing fluid that is unsaturated in the dissolving species (as defined in the original ASME document. This mechanism is also known as flow-assisted corrosion or flow-induced corrosion.

Fretting corrosion: Fretting refers to metal deterioration caused by repetitive slip (on the order of microns) at the interface between two contact surfaces. Small metallic particles spall during metal-to-metal contact and continue to induce damage. This mechanism is often called fretting corrosion because of the red oxide produced by oxidation and fretting when one or both alloys are ferrous-based.

Galvanic corrosion: Corrosion caused when a metal or alloy is electrically coupled to another metal or conducting nonmetal in the same electrolyte. When

dissimilar metals are electrically coupled, the current flow between the metals causes increased corrosion of the less corrosion-resistant metal and decreased corrosion of the more corrosion-resistant metal.

Gas-side decarburization: A high-temperature gas-metal reaction whereby carbon (typically in the form of pearlite or iron carbides) is selectively removed from the surface of a metal alloy. High concentrations of carbon dioxide can combine with iron carbide in the steel to form iron and carbon monoxide at high temperatures. Reduction in the carbon content typically reduces surface strength.

Gas-side dew point corrosion: Corrosion caused by the formation of acids, typically sulfuric acid, when the combustion flue temperatures drop below the condensation point for the acid present as a vapor in the flue stream. This condition can cause pitting corrosion during shutdowns of equipment that typically sees elevated temperatures in service. Such corrosion most often occurs during the shutdown of components that operate above dew point temperature.

General corrosion: Non-localized corrosion that occurs over a large percentage of the metal surface, resulting in uniform metal loss. Seawater flowing over carbon steel, for example, can generate general corrosion.

High-cycle fatigue (vibration): Fatigue associated with low-amplitude, high-frequency compression-relaxation cycles from vibrational loading.

High temperature oxidation: Also known as thermal oxidation, this is a reaction where the metal or alloy is converted to an oxide due to exposure to elevated metal temperatures in an environment that allows the metal to combine with oxygen at excessive rates.

Hydrogen damage: A general term for the embrittlement, cracking, blistering, and hydride formation that can occur when hydrogen is present in some metals.

Liquid droplet erosion: A wastage mechanism caused by impingement of droplets of a liquid entrained in a vapor or gas stream at high relative velocity to a solid surface.

Microbiologically influenced corrosion (MIC): MIC is an electrochemical process in which the source is biological.

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Consensus on Pre-Commissioning Stages for Cogeneration and Combined-Cycle Power Plants continued

MIC is often caused by sulfate-reducing bacteria, but other biological initiators also exist. Chemistry changes can be brought about by the depletion in oxygen and the production of enzymes and waste metabolites. Direct metal dissolution can also be incurred due to oxidation-reduction reactions of the microorganismâ&#x20AC;&#x2122;s metabolism. MIC can occur at temperatures up to 235 °F and often occurs in stagnant flow conditions.

Figure 9: Three groups of major factors determining susceptibility to stress-corrosion cracking.

Pitting corrosion: Corrosion of metal surfaces confined to small points or areas that takes the form of cavities in the surface. Pits result from localized galvanic cells that often are associated with local discontinuities, including inclusions, local deposits, or local composition deviations.

Phosphate gouging: The dissolution of carbon steel by localized high concentrations of mono- or disodium phosphate to form maricite (NaFePO4) and other sodium-iron-phosphate compounds. Crusty, alternating black-and-white layered deposits may remain with knife-edge-like surfaces in the gouged area. This form of corrosion also requires a phosphate-concentrating mechanism, such as steam blanketing or boiling within porous deposits, and the development of a thermal barrier between the tube metal and the boiler water.

Stress-assisted corrosion (SAC): Corrosion caused by a combination of high local stress, either applied or residual, and a corrosive environment. Highly localized stress can cause breaks in the protective oxide film, so that the presence of a corrosive environment initiates attack where the film is broken. Often the attack appears as cracks composed of a series of interconnected pits. (SAC is a process in which either an applied stress or residual stress is present that causes a break in the protective oxide that does not self-repair at a rate fast enough to prevent the corrosive environment from accelerating the corrosion).

Three groups of major factors determining susceptibility to SCC. Specific values are required within each group for SCC to occur. In contrast, corrosion, fatigue and corrosion-fatigue require specific values in only two groups of factors. These are illustrated in Figure 9.

Thermal Fatigue: Fatigue associated with cyclic temperature changes that cause the metal to expand and contract. The mechanism is considered to be high-amplitude, low-frequency, low-cycle fatigue.

Under-deposit corrosion: Corrosion damage mechanisms where apparent surface deposits are present and damage occurs under the deposits. The deposit sources may have come from upstream or may have been generated by the corrosion mechanisms (e.g., caustic gouging, hydrogen damage, and phosphate corrosion) themselves.

Stress corrosion cracking (SCC): A cracking process that requires the simultaneous action of a corrodent and sustained stress acting on a susceptible material.

Cracking damage can appear as intergranular or transgranular, multi-branched cracks, depending on the alloy and the environment. Cracks are typically non-oxide-filled and branched along their lengths.

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2020 ANNUAL CONVENTION & EXPOSITION S E P T E M B E R 3 0–O C TOB E R 3 , 2 02 0

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Convention Preview It's Happening!

As of the printing of this issue the Analyst, we are hopeful that we will all be able to safely gather together in Louisville. However, the AWT Convention Committee and Leadership Team are closely monitoring the situation with COVID-19. If it is unsafe to meet, or if we are unable to meet in person, rest assured that our Annual Convention & Exposition will still take place! We are working on an exciting contingency plan for a robust virtual meeting!

The AWT Annual Convention & Exposition is a time where industry leaders learn new ways to lead high-performing companies, improve sales, and better understand the challenges facing all of us. These interactions are vital to staying current and energized. The educational program involves knowledgeable subject-matter experts to ensure that you get the essential updates, fresh strategies, and practical advice you need.

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Visit our website awt.org/annual-convention-2020 for more details.

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Convention Preview continued

Hotels

Reflecting the past, present, and future of an exciting Kentucky town, the Omni Louisville Hotel, our headquarters hotel, is the new cornerstone of downtown. The location allows you to easily make your way to Main Street and indulge in Louisville's many popular restaurants and distilleries. Blending the historic surroundings with modern comforts, the Omni Louisville Hotel reflects the essence of the city and invites you have an unforgettable stay.

AWT also has a block of rooms at the Marriott Louisville Downtown. Both hotels are equidistant from the Louisville Convention Center, where you will find the exhibit hall and education sessions. And, both hotels are a short, 15-minute ride from the Louisville Mohammed Ali International Airport, 96 miles from Cincinnati/Northern Kentucky International Airport, and 115 miles from Indianapolis International Airport.

Educational Program

But of course, you don’t just come to an AWT Annual Convention for the location—you come for the education.

We’ll start the educational sessions out right with a keynote session discussing how to deal with stress and covering the guidelines that are crucial to applying humor as a business skill. Humor can positively affect productivity at work. As a strategic skill, it plays a constructive part in communication, morale, and stress

reduction. Explore ways to steer clear of controversial humor that may become a source of problems and complaints. Learn how to use humor that enhances (and never diminishes) workplace culture while improving morale and ultimately, customer service.

Throughout the course of the meeting, there will be tracks on water treatment, wastewater, equipment, corrosion, and cooling water treatment as well as sessions on boilers, RO, Legionella, and potable water. Here are just a handful of the sessions that will be held during the convention: Cooling Towers and Water Management Programs The EPA New Proposed Lead and Copper Rule: How It Can Impact Your Business Enhancing Efficiencies in Condenser Water Systems Implementing a Sustainable Solution for Cooling Tower Treatment in the Food Industry 2020—The Future of Water is Now! Innovations Improving Efficiencies in Production and the Field Role of Water and Water Treatment in Renewal Energy Production

Thank You to Our Sponsors

AWT would like to thank our convention sponsors (as of 4/28/2020): AquaPhoenix Scientific, Inc. Buckman Carlon Meter, Inc. Environmental Safety Technologies, Inc. Evapco French Creek Software, Inc. Grundfos McGowan Insurance Group

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Myron L Company Peabody Engineering & Supply, Inc. Scranton Associates, Inc. Taylor Technologies, Inc. Tiarco Chemical Wincom ZIBEX, Inc.

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New Exhibitors and Vendors

Finding the right solution providers is essential to your company’s success. The AWT Exposition was created to be your one-stop destination for finding the right solutions to guide your company into the future. You can walk the show floor and browse categories ranging from equipment providers to blenders and everything in between. Check out the 2020 AWT Annual Convention & Exposition to find solutions today! Some of this year’s exhibitors include: Lakewood Instruments LLC Lovibond Lubrizol Corporation, The LuminUltra Technologies Ltd. Lutz-Jesco America Corp.

Marlo, Inc. Masters Company, Inc. McGowan Insurance Group Metal Samples Co. Myron L Company Neptune Chemical Pump Co. North Metal & Chemical Company Nouryon Surface Chemistry NuStream Filtration, Inc. ODYSSEE Environment Peabody Engineering & Supply Inc. PEAK Commercial & Industrial/Thermal Charge Phigenics, LLC ProMinent Fluid Controls, Inc. Pure Water For the World Pyxis Lab, Inc. QualiChem, Inc. Quantrol, Inc. Radical Polymers Sanipur US LLC Shandong Green Technology Co. Ltd. Sigura Smart Release SNF Inc. Solid State Technologies, LLC Spartan Bioscience Special Pathogens Laboratory Spectra Colors Corporation Stenner Pump Company Suez Water Technologies & Solutions Taylor Technologies, Inc. Tiarco Chemical Uniphos, Inc. Univar USABlueBook U.S. Micro-Solutions, Inc. Vector Industries, Inc. Walchem, IWAKI America Inc. Wincom, Inc.

Aceto Corporation ADEY Innovation LLC Advantage Controls, Inc. Aerobiology Laboratory Associates Albemarle Corporation American Water Chemicals, Inc. AmeriWater AMSA, Inc. APTech Group, Inc. AquaMedix Aquapharm Chemicals Pvt. Limited AquaPhoenix Scientific Inc. Bio-Source, Inc. Biosolutions, LLC Brenntag North America Carlon Meter, Inc. CDG Environmental, LLC CHEMetrics Chemtrol Commonwealth Chemical Specialties, LLC Cortec Corporation Creative Water Solutions LLC Droycon Bioconcepts Inc. Earthwise Environmental, Inc. Eddington Industries, LLC EMEC EMSL Analytical Inc. Enviro Tech Chemical Services, Inc. Environmental Safety Technologies, Inc. Equip Solutions ESOPMarketplace.com Eurofins EMLab P&K French Creek Software, Inc. GEO Specialty Chemicals HC Info Heyl Brothers North America L.P. Houghton Chemical Corporation IDEXX Innovative Waters, LLC International Dioxcide, Inc. Interstate Chemical Co., Inc. Italmatch USA Corp.

Justeq, LLC Kemira KOST USA, Inc.

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Networking Opportunities

Annual Reception and Awards Dinner

Golf Tournament

The details of the Annual Reception and Awards Dinner are being worked out, but in addition to the awards segment of the evening, there will be entertainment and tours. It will be a memorable event!

The AWT Annual Convention is the only place in the water industry where you can meet people who are confronted with the same challenges as you. As small to medium-sized businesses, attendees at the annual convention can relate to the exact challenges you face.

And as we all know, networking is one key factor in being a successful business owner. The best way to get through tough times, be it a business slump or times of incredible growth, is to have a trusted peer in the industry who you can turn to for advice and counsel.

The Annual Reception and Awards Dinner will be held at Churchill Downs, home of the Kentucky Derby.

Horse racing in Kentucky dates back to 1789, when the first race course was constructed in Lexington. Almost 100 years later, in 1875, Churchill Downs officially opened its gates in Louisville and began its tradition as the longest continually running sporting event in America.

Our annual golf tournament will be held at Fuzzy Zoeller’s Covered Bridge Golf Club. Covered Bridge is a Fuzzy Zoeller/Clyde-Johnston-design 18-hole golf course carved through the gorgeous landscape of southern Indiana. Each hole of this par 72 layout offers a new and exciting challenge from tee to green. Paved cart paths bring these 18 holes together, connecting tee boxes to the course’s Zoysia grass fairways. Multiple lakes and strategically placed bunkers add to the beauty of the slightly undulated greens. Covered Bridge is a Uniphos 2020.pdf 1 4/23/2020 3:57:49 PM demanding yet fair test for every golfer.

Register Today!

This is one convention you can’t afford to miss! Visit https://www.awt.org/annualconvention20/ for extensive information about the convention. We hope to see you there!

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A US-based company helping North American water treatment chemical companies, blenders, and distributors.

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Uniphos, Inc.

1011 West Lake Street Suite 210 Oak Park, IL 60301

Phone: 708 445-1294 • Fax: 708 445-1394 • Email: gcollias.uniphos@sbcglobal.net

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the Analyst Volume 27 Number 2

Membership Benefits

ASHRAE and CTI Updates

of the water treatment industry that they are. In 2005, when ASHRAE endeavored to develop and eventually publish the FIRST (and still only) U.S. Standard for Legionella (in 2015), AWT was well positioned to have a prominent role in the development of Standard 188. The AWT Liaison to ASHRAE is the current vice-chair of the standing 188 committee, including being a significant (AWT) voting member of the latest ASHRAE Standard 514 under development (from NSF 444).

ASSE (International Association of Plumbing and Mechanical Officials): AWT is recognized as an organizational representative voting member on the ASSE Qualifications Standard 12080 Working Group, which approved a final draft document in early February 2020. It was subsequently approved by an ASSE Professional Qualifications Standards Committee and sent out for a 45-day public review period, per ANSI requirements, which ended March 30, 2020. The public review comments are currently being reviewed, and if they don’t result in any changes to the standard (other than editorial), it will be filed by ASSE with ANSI to be recognized as an ANSIapproved standard, which could actually happen in early May. If the public review results in changes to the draft that are deemed substantial, then the draft will have to go through another public review period of 30 or 45 days. We think it’s not going to require such review.

CTI Bill also attended the CTI Annual Conference and Expo in Houston, Texas, February 9–13, 2020. Bill is the chair of GDL 159, Legionella and also attended other Task Group Reports, including WTG 126, Application of Non-Oxidizing Biocides; WTG 130B, Deposit Monitoring; WTG 142, Galvanized/White Rust; WTG 155, Cooling Water Reuse; WTG 161, Best Practices Guidelines for Cooling Water Systems; WTG 168, External Reuse for Cooling Water Makeup; and STD 149, Corrosion Testing Procedures. CTI deals with many of the same cooling tower water treatment technical topics as AWT and our presence at CTI ensures that we are relevant.

Did you know that AWT represents you in the industry?

As part of AWT’s overall advocacy efforts to become the global voice of the water treatment industry, representatives from AWT liaise with multiple organizations with water treaters from around the world. Liaisons will sit on committees, attend events, and build relationships on behalf of AWT. Following is an update from ASHRAE and CTI from RTO Liaison Bill Pearson, CWT.

ASHRAE AWT RTO Liaison to ASHRAE, Bill Pearson, CWT, attended the ASHRAE Winter Meeting and Expo in Orlando, Florida, February 1–5, 2020. Bill presented a session on Cooling Tower Water Treatment 101 for the Expo Seminar program on behalf of CTI and was recognized as AWT Liaison to CTI and ASHRAE. Bill is also part of two committees—the TC3.6 Water Treatment Technical Committee and the SSPC 188 (Legionella and Guideline 12) Committee. Through Bill’s work, AWT has become recognized as the significant water treatment organization and very much the “voice” 67

Earlier this year, CTI released its Comprehensive Legionellosis Guideline (GDL) 159 – Practices to Reduce the Risk of Legionellosis from Evaporative Heat Rejection Equipment Systems. This new document provides comprehensive guidance specifically for owners, operators, water treatment professionals, and others involved in the monitoring and care of cooling systems utilizing evaporative heat rejection. GDL-159 was developed by a committee of industry professionals, including water treaters, microbiologists, manufacturers, suppliers, and equipment owners and operators per the CTI consensus-based approval process. The guideline covers such areas as basic Legionella microbiology, risk assessment, general maintenance and inspection, equipment operations, and recordkeeping. GDL-159 can be used as a resource in the development of Water Management the Analyst Volume 27 Number 2

Membership Benefits continued

Plans, such as those required by ASHRAE Standard 188-2018, Legionellosis: Risk Management for Building Water Systems.

AWT Benefits Program

AWT is pleased to offer members a comprehensive and affordable health benefits solution that meets all the compliance requirements of the Affordable Care Act (ACA). This program is designed to help AWT members strategically manage healthcare costs while still providing employees with great benefits!

Your Company Can Enjoy: Flexible, level-funded medical plans.

Value-added benefits to save on out-of-pocket expenses.

Association-negotiated economies of scale pricing.

Integrated wellness with deductible credits and cash rewards.

Premium savings of 5–15% from traditional plan designs.

Consumer-driven features for proactive cost containment.

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Why Is the Lifestyle Health Program So Unique?

Level-funded group medical plans underwritten by “A” rated carriers.

Premium savings averaging 5–15%.

Up to a $500 deductible credit available to all wellness participants.

Integrated cash rewards and incentives for lifestyle improvement.

24/7/365 telemedicine access.

Innovative prescription, outpatient lab, and diabetic supply coverage included.

Proactive cost-containment measures integrated into every plan design.

For more information, please contact Hillary Thompson at (574) 231-6530 or hthompson@keystoneinsgrp.com.

the Analyst Volume 27 Number 2

Association News Charity Update

AWT members are making a big impact with Pure Water for the World, raising over $50,000 in 2019 that will support water projects in three small communities in Hondurasâ&#x20AC;&#x201D;El Horconcito, Las Uvillas, and La Union.

The funds from AWT members are supporting projects to transform the lives of the people in these communities. Projects include home water filter installation, community training to help local people take ownership of water projects, and hygiene training for the community and local schools.

Following is an update from the recent Community Agent training that took place in El Horconcito, Hondurasâ&#x20AC;&#x201D;the community you all so generously helped fund.

These volunteer Community Agents will work with the PWW team to install water filters in homes. Each will be responsible for three or four homes. They will visit their assigned families regularly to ensure that the filters are working properly, that the families understand how to use the filter and are utilizing safe hygiene practices, and that the families are benefiting from drinking and washing with the filtered water. The Community Agents work closely with PWW to troubleshoot any issues.

They take their jobs seriously and are invaluable to the community's ownership of their water project and to the long-term sustainability of the tools and practices.

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the Analyst Volume 27 Number 2

Industry Notes Dayton Business Owner Named Among World's Top Women Entrepreneurs

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Lois Elrich, president of Dayton-based water technologies company Solid Blend, is among 113 international winners of the 2020 Enterprising Women of the Year Awards.

The annual tribute to the world's top women entrepreneurs is put on by Enterprising Women magazine. It is considered one of the most prestigious recognition programs for women business owners, according to a press release.

Xylem Introduces Industrial-Strength Product Lines to Handle Critical Industrial Challenges

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To win, nominees must demonstrate they have fastgrowth businesses, mentor or actively support other women and girls involved in entrepreneurship, and stand out as leaders in their communities. Many of the honorees also serve as leaders of key organizations that support the growth of women’s entrepreneurship.

Elrich is among 12 winners in the $4 million to $5 million annual sales category. Winners are recognized in categories ranging from less than $1 million to over $50 million and come from all over the world, including New York City, Dubai, Nairobi, Chicago, London, and Japan.

Honorees will be recognized at the 18th Annual Enterprising Women of the Year Awards Celebration & Conference, scheduled for October 18–20, 2020, at the Wyndham Grand in Clearwater Beach, Florida.

Large-capacity vertical turbine, multistage ring section, 2 4 and double suction centrifugal pumps solve water and fluid management-intensive applications.

Xylem expanded its pump portfolio to include the e-MP multistage ring section pumps, e-XC single-stage double suction centrifugal pumps, and larger vertical turbine pumps. From intake to discharge, Xylem’s products provide a wide range of industrial applications with increased production and profitability.

Designed to address the biggest issues in industrial pumping and processes, including minimizing downtime, costs, and environmental impact and boosting and transporting water as efficiently as possible, these products integrate with industrial operations for sustainable production.

In addition to her role as president of Solid Blend, Elrich is also a WBE-certified executive leadership coach and facilitator for Aileron. “It’s an honor to be counted among a group of women who are working hard to lead their businesses and give back to their communities and other women," Elrich said. "I’m passionate about developing teams and coaching to build relationships. It’s my privilege to be able to do what I love both as a leader at Solid Blend and as a mentor for others."

Founded in 1999, Solid Blend is a woman-owned business that specializes in healthcare water management solutions, with a focus on Legionella detection, remediation, control, and outbreak response. The company employs 15 people at its Dayton headquarters.

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“Industries ranging from pulp and paper to automotive to food and beverage rely on technology, innovation, and dependability in the products they choose to strike the right balance of output, efficiency and costs,” said Joshua the Analyst Volume 27 Number 2

Industry Notes continued

Allen, Xylem Industrial Solutions director of marketing, Americas. “Drawing on more than 170 years of experience, our experts developed these solutions to minimize downtime and meet environmental regulations.”

Xylem’s e-MP, e-XC and vertical turbine pumps are customizable to meet the demands of industrial applications—from water intake and boosting to wastewater discharge. Built on the thinking that every step in industrial operations is part of a process versus a stand-alone function, these products are safer, stronger, and more efficient for lower lifecycle costs and energy demands. More benefits of the products are outlined below.

Marianne Metzger Joins ResinTech Lab Services

Ion exchange manufacturer ResinTech® announced that it hired Marianne Metzger to lead business development efforts for the company’s Laboratory Services Division. Ms. Metzger brings over two decades of environmental testing experience, including nearly five years in leadership positions at the Eastern Water Quality Association (EWQA).

Before joining ResinTech, she held sales leadership positions at National Testing Laboratories in Cleveland, Ohio, and CNA Environmental in Ballston Spa, New York.

e-MP – The multistage ring section pump is ideal for high-pressure applications, such as filtration, reverse osmosis, boiler feed, and scrubbers. Versatile mechanical configuration and optimized pump hydraulics enable reduced energy consumption and wear and tear, while intelligent pumping features boost monitoring and control performance with multiple sensor interfaces and options.

An avid gem mining enthusiast, Ms. Metzger graduated from Case Western Reserve University with degrees in environmental geology and political science. “Marianne’s passion for geology, her credibility in the water industry, and her deep business development track-record make her ideally suited to help us grow our lab services business. We are all delighted he has chosen to join ResinTech,” said company president Larry Gottlieb.

e-XC – Designed for maximum durability and performance in even the harshest environments, the e-XC comes in multiple models and configurations and a wide range of materials to handle aggressive applications. A corrosion-resistant stainless steel impeller and wear rings as standard reduce downtime, increase efficiency, and enhance overall performance.

The addition of Ms. Metzger comes at a pivotal moment for ResinTech. The company recently increased its already formidable lab services capability by investing in the highly sensitive equipment necessary for detecting PFAS compounds and other emerging contaminants at minuscule concentrations. This summer, the company that started in founder Michael Gottlieb’s basement will open its new $138.8 million, 27-acre campus, where it expects to produce over 500,000 cubic feet of solvent-free cation resin annually. The company will also consolidate operations of its filter and lab water unit, Aries FilterWorks, and its resin regeneration division, ACM Technologies.

Vertical turbine pump – The efficient extension to the existing Xylem vertical turbine product line, it’s scaled with capacities up to 50,000 gpm for the largest industrial fluid needs, including raw water intake and boosting, fluid transfer, and machine tool cooling.

With bowl efficiencies near 90% and broad hydraulic coverage, operators can realize greater energy savings while maintaining pumping power.

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Acuren, Inc. Acquires M&M Engineering Associates, Inc. Acuren Inc., the global provider of nondestructive testing (NDT), inspection, and related services, is pleased to announce the acquisition of M&M

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Industry Notes continued

Engineering Associates, Inc., a leading U.S. provider of field and lab engineering services to the power generation, pulp and paper, chemical, and manufacturing segments. Through its state-of-the-art integrity management, shutdown planning, and failure analysis capabilities, M&M Engineering helps clients manage operational risk while reducing their overall cost of operation.

This exciting combination enables Acuren, an established leader in NDT for over 40 years, to bring integrated assessment and inspection solutions to its valued customers across the United States. Acuren, a wholly owned subsidiary of Rockwood Service Corporation, also provides a range of inspection and engineering services in Canada.

Solenis to Acquire Paper Business of Water Chemicals Provider

“We are delighted to welcome the M&M Engineering team to the Acuren family,” said Peter Scannell, Rockwood’s founder and president. “M&M shares Acuren’s commitment to developing customized engineering and inspection programs that enable plants to optimize the life cycle of their critical assets. We are excited about bringing more value to our collective customers through combining Acuren’s best-in-class inspection, condition monitoring, and rope access capabilities with M&M Engineering’s deep expertise in metallurgical condition assessment, risk-based evaluation, and failure analysis.”

“This is an excellent opportunity to continue to consolidate our channel to market after the recent successful merger of BASF’s Paper and Water Chemicals business with Solenis.” said John Panichella, president and CEO, Solenis. “We have had an exceptional working relationship with ChemSystems for many years, and this acquisition will allow Solenis to directly provide value to pulp, paper and tissue markets in South Africa.”

Karen Fuentes will continue to oversee the M&M organization and its experienced team of engineers and technical experts. Mrs. Fuentes commented, “We are highly enthusiastic about this new partnership and the broader set of capabilities that we can provide. Having worked together with Acuren in the past, we know that Acuren shares our commitment to quality, safety and continuous improvement.”

Effective February 28, 2020, Solenis signed an agreement to acquire the paper business of ChemSystems, a division of AECI Ltd. The transaction is expected to close in the second quarter of 2020.

Headquartered in Johannesburg, South Africa, ChemSystems produces and supplies specialized chemical solutions for water-intensive industries, including the pulp, paper and tissue manufacturing industries in South Africa and Sub-Saharan Africa. Until this acquisition, the business was Solenis’ pulp and paper specialty chemical distributor in Africa.

Mark Dytor, chief executive of AECI, added, “Through ChemSystems, we have partnered with South Africa’s pulp and paper customers for many years. Excellent relationships have been developed, and I am certain that these will be enhanced further by Solenis.”

For additional information about Solenis, please visit www.solenis.com.

For more information, visit www.mmengineering.com.

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the Analyst Volume 27 Number 2

CWT Spotlight

Amy Pollock, CWT Chemtron Corporation Jacksonville, Florida

What prompted you to obtain your CWT and when did you begin the process by taking the test?

The certification is so important to our field. It gives our clients confidence in our professionalism. Additionally, apathy can be a pitfall to anyone in the work field.

Obtaining and maintaining the CWT certification is a surefire way of combating this. After 15 years of industry experience, the time was right for me to step up to the challenge.

I also saw the changing needs as a supplier to the healthcare industry. The CWT is becoming more and more prevalent with regards to writing WMPs. When public safety is concerned, our clients need to know that the people they rely on are educated in the field and are committed to continuous education.

What advice would you give those thinking about taking the exam?

If you are considering the CWT, know that it is a process. While the test is the biggest piece, there is more to it. Itâ&#x20AC;&#x2122;s a commitment to continuing your education and taking your career path to the next level. I would tell anyone considering this path to sign up for the test first. The demands of a water treater are only growing.

Balancing work and family is difficult, and obtaining the CWT takes a serious commitment. It is so easy to put our own needs at the bottom of the pile. Sign up for the

test before you do anything else so that you have a firm deadline! Secondly, take the AWT training course! It is crucial in the preparation process.

What was the most difficult aspect of the exam?

The exam covers the gamut of water treatment! Itâ&#x20AC;&#x2122;s not enough to be an expert in one or two areas of our industry. Taking a step back and relearning topics covered in chemistry and biology was enlightening and pretty fun. Taking on challenges and choosing to exercise your mind are so important to personal growth and development How did you prepare for the test?

The AWT training course was crucial to the process of obtaining the CWT. Additionally, I used the AWT training manuals, the practice tests, and mentors! Never take for granted the power of experience! Tony LaRussa, long-time Cardinals manager would always put the veterans in over the rookies to win an important game.

I followed his logic in using the people around me who had more experience.

Why do you feel this credential was important to have?

This credential is popping up in more and more bid specifications. It also gives clients a sense of ease with regard to writing water management plans and chemical program management.

Congratulations to Our Newest CWTs Please join us in congratulating the latest individuals to become CWTs (January 31, 2020-April 15, 2020) Ryan Cochran, CWT, AquaTrol - Division of Momar, Inc.

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Patrick Shaver, CWT, Global Water Technology, Inc.

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Making a Splash

John W. Humphrey, CWT Technical Director

Anderson Chemical Company River Falls, Wisconsin

What prompted you to start volunteering with AWT? My mother and father were both involved in volunteer work over the years, and it was a large part of my upbringing. My father often had sage advice for me and my siblings that included the phrase “pay it forward,” before that was well known. He encouraged us to volunteer for things where we could make a difference. When my company became a member of AWT, I was able to observe the organization and how everyone worked together toward a common goal of shared knowledge and experience. I was able to meet a number of great mentors that were volunteers for AWT, who encouraged my participation and shared many of the same values my father had expressed. Volunteering for AWT is a way for me to help people who are in the position I was when I first attended AWT events. If I can serve others by volunteering and helping to increase knowledge, then we can grow the service AWT can provide. Volunteering for AWT has been rewarding and a whole lot of fun!

How has volunteering improved your professional career?

By volunteering I have met a number of really smart, really wonderful people from whom I have gained a large amount of knowledge. Working with these incredible people has helped me with my knowledge base, which I can share with our field personnel at Anderson Water Management. In addition, my presentation skills and my ability to organize has improved through my volunteer work with AWT. Meeting other water treatment professionals from various companies and suppliers has led to some partnerships that have been mutually beneficial.

Volunteering and being a part of AWT has definitely made me a better water treatment professional.

Why would you encourage others to become a volunteer?

Most water treatment professionals are quite passionate about their work. Usually, there is one area of water 74

treatment that they find the most exciting. My area of extra excitement is in wastewater treatment. Others may have that special passion for boilers, cooling , process waters, reverse osmosis, or legislative matters.

Volunteering allows individuals to share their passion and knowledge and can be very rewarding. Imagine how you feel when you are attending training or a seminar and there is a subject that you finally understand based on what you’ve learned. Now imagine being the person who is able to help others achieve that understanding. It’s a fantastic feeling and really shows how you can have a positive impact on others and serve them by passing along your knowledge. This is why AWT is such a tremendous organization—water treatment professionals helping other water treatment professionals reach their greatest potential. I encourage everyone who is an AWT member to consider volunteering, as it is a way to pay back and further the service to others. That is a hallmark of AWT.

Tell us about a current project you or your committee is working on?

I have only recently become the chair of the Wastewater Subcommittee, and a project that the subcommittee has been working on for a while now is to update the wastewater chapter in the AWT water treatment manual. It is a comprehensive chapter that deals with all matters in wastewater treatment, and I am proud to participate.

This project is a perfect example of water treatment professionals coming together to work toward a common goal, with many members of the subcommittee able to provide insight and knowledge. The finished project will help all AWT members to gain a better understanding of wastewater and how to gain more business for themselves and their individual companies. Projects like this are critical to allow AWT to grow and remain an important part of the water treatment industry.

the Analyst Volume 27 Number 2

Capital Eyes

EPA Revises Rules for Storing Chemicals The Environmental Protection Agency (EPA) has proposed changes to its National Pollutant Discharge Elimination System (NPDES) 2020 issuance of the Multi-Sector General Permit (MSGP) for Stormwater Discharges. The proposed permit, once finalized, will replace the EPA’s existing MSGP that will expire on June 4, 2020. The EPA proposes to issue this permit for five years and to provide permit coverage to eligible operators in all areas of the country where the EPA is the NPDES permitting authority.

Background

Section 405 of the Water Quality Act of 1987 added section 402(p) of the Clean Water Act (CWA), which directed the EPA to develop a phased approach to regulate stormwater discharges under the NPDES program.

This 2020 MSGP will cover stormwater discharges from industrial facilities. The proposed permit is similar to the existing permit and is structured in nine parts: general requirements that apply to all facilities (i.e., eligibility requirements, effluent limitations, inspection and monitoring requirements, Stormwater Pollution Prevention [SWPPP] requirements, and reporting and recordkeeping requirements) (Parts 1–7); industrial sector-specific conditions (Part 8); and state and tribal-specific requirements applicable to facilities located within individual states (Part 9).

After the EPA issued the 2015 MSGP, numerous environmental nongovernmental organizations (NGOs) challenged the permit; two industry groups intervened, and a settlement agreement was signed in 2016 with all parties. The settlement agreement stipulated several terms and conditions that the EPA agreed to address in the proposed 2020 MSGP. One key term from the settlement agreement stipulated that EPA fund a study conducted by the National Academies of Sciences, Engineering and Medicine’s National Research Council (NRC) on potential permit improvements, focused 75

primarily on monitoring requirements for consideration in the next MSGP. The NRC study’s overarching recommendation is that the MSGP is too static and should continuously improve based on best available science, new data, and technological advances. Below are some of the study’s recommendations, as well as details on how EPA is addressing these recommendations in this proposed rule.

MSGP Pollutant Monitoring Requirements and Benchmark Thresholds: Industrywide monitoring for pH, total suspended solids (TSS), and chemical oxygen demand (COD) as basic indicators of the effectiveness of stormwater controls employed on site. EPA Response: Proposes to require universal benchmark monitoring for these substances for all facilities.

Process to periodically review and update sector-specific benchmark monitoring requirements to incorporate new scientific information. EPA Response: Proposes revisions to the MSGP’s sector-specific fact sheets and proposes specific benchmark monitoring for certain sectors.

Benchmark levels based on the criteria designed to protect aquatic ecosystems from adverse impacts from short-term or intermittent exposures which to date have generally been acute criteria. EPA Response: Proposes to update benchmark thresholds for aluminum, selenium, arsenic, cadmium, magnesium, iron, and copper based on the latest toxicity information.

Sampling and Data Collection: Allowance and promotion of the use of composite sampling for benchmark monitoring for all pollutants except those affected by storage time. EPA Response: Proposes an explicit clarification that composite sampling is allowed for benchmark monitoring. the Analyst Volume 27 Number 2

Capital Eyes continued

For permittees with average results that meet the benchmark, a minimum of continued annual sampling to ensure appropriate stormwater management throughout the remainder of the permit term. EPA Response: Proposes that facilities monitor and report for these three parameters on a quarterly basis for the entire permit term, regardless of any benchmark threshold exceedances.

Public sign of permit coverage. EPA Response: Proposes to include a requirement that MSGP operators must post a sign of permit coverage at a safe, publicly accessible location in close proximity to the facility.

The EPA proposes that this notice must also include information that informs the public on how to contact the EPA if stormwater pollution is observed in the discharge.

A tiered approach to monitoring that recognizes the varying levels of risk among different industrial activities and that balances the overall burden to industry and permitting agencies. EPA Response: Proposes to have the following tiered approach to monitoring: 1) A possible inspection-only option available to low-risk facilities; 2) require new universal benchmark monitoring for pH, TSS, and COD; 3) continue existing benchmark monitoring requirements for the 2015 MSGP; and 4) require continued benchmark monitoring as a part of the proposed Additional Implementation Measures.

Consideration of major storm control measure enhancements. EPA Response: Proposes that operators would be required to consider implementing enhanced measures for facilities located in areas that could be impacted by stormwater discharges from major storm events that cause extreme flooding conditions.

Recommendations for Stormwater Retention to Minimize Pollutant Loads: Incentives to encourage industrial stormwater infiltration or capture and use where appropriate. EPA Response: Proposes infiltration, where the operator can demonstrate to the EPA that it is appropriate and feasible for site-specific conditions, as an alternative or adjunct to structural source controls and/or treatment controls.

Permit Changes: Streamlining of permit. EPA Response: Proposes to streamline and simplify language throughout the permit to present the requirements in a generally more clear and readable manner.

Eligibility for stormwater discharges to a federal CERCLA site. EPA Response: The 2015 MSGP requires facilities in EPA Region 10 that discharge stormwater to certain CERCLA or Superfund sites to notify the EPA Regional Office in advance and requires the EPA Regional Office to determine whether the facility is eligible for permit coverage.

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Impaired waters monitoring. EPA Response: Under the 2015 MSGP, operators discharging to impaired waters must monitor once per year for pollutants for which the waterbody is impaired and can discontinue monitoring if these pollutants are not detected or not expected in the discharge. The EPA proposes to require operators discharging to impaired waters to monitor only for those pollutants that are both causing impairments and associated with the industrial activity and/or benchmarks. The proposal specifies that, if the monitored pollutant is not detected in your discharge for three consecutive years or it is detected but you have determined that its presence is caused solely by natural background sources, operators may discontinue monitoring for that pollutant.

To read the proposed rule in its entirety, see https:// www.govinfo.gov/content/pkg/FR-2020-03-02/ pdf/2020-04254.pdf.

Janet Kopenhaver is president of Eye on Washington and serves as the AWT Washington representative. She can be reached at (703) 528-6674 or janetk@eyeonwashington.com.

the Analyst Volume 27 Number 2

Financial Matters

Running Your Personal Finances Like a Business Most individuals don’t regard themselves as businesses, trying to turn a profit and beat the competition. But, occasionally, it may help to look at your financial situation this way to determine where you might cut expenses and boost cash flow. Here are some tips.

Lay Out Your Financials

Where an executive might reach for financial statements to get a read on the company’s standing, you can create or update a net worth statement. Essentially a monetary scorecard, a net worth statement helps you determine where you stand financially and whether you’re on track to meet your goals.

You can calculate your net worth by adding all your assets, including cash and cash equivalents, brokerage account balances, retirement funds, real estate and other fixed assets and personal property. Then subtract your liabilities, including mortgages, personal loans, credit card balances and taxes due.

The result provides some important clues about where your money is going and how you might be able to trim spending and increase savings. Are you overrelying on credit cards with high interest rates? Could you cut back on food or entertainment costs?

Practice Risk Management

To maintain their companies’ financial health, business executives also practice risk management. You can do the same by first assessing compensation and benefits elections. A major life change—such as a marriage or birth—may require an update to your W-4 withholding allowances with your employer.

Unexpected medical costs can be a huge risk. Review your health insurance to ensure it’s providing the best value. Now might not be an ideal time to switch to a spouse’s plan but, if it’s a better deal, perhaps make a note to do so when you can. Also, if you have a Health Savings Account or Flexible Spending Account, make sure you’re using it to your full advantage.

in your homeowner’s coverage. Or maybe you no longer have enough life insurance to protect your growing family. Talk to your insurance professional to determine the right amount of coverage.

Finally, check your credit report. If you wait until something is obviously wrong, it may be too late to prevent significant damage. Federal law requires the three major credit reporting agencies to provide you with one free report per year.

Think About Retirement

Business owners must think about succession planning.

But even if you don’t own a company, you should think about life after employment.

If your employer allows you to adjust your retirement plan contributions during the year, consider boosting them to take full advantage of tax-deferred compounding and, if available, employer matching. Similarly, if you plan to make an IRA contribution this year, do so as early as possible to give your assets more time to grow.

Also review your estate plan and, if necessary, update it.

Financial priorities change over time, so make sure the beneficiary designations for your retirement accounts and insurance policies still match your wishes. Check your will or living trust to ensure no changes are necessary.

And, if you’re looking to reduce the value of your taxable estate, remember that you can make $15,000 ($30,000 for married couples) in annual exclusion gifts per recipient this year without using up any lifetime exemption.

Get Rolling

Some might say that the beginning of the year is the most important time for financial planning. Others might say it’s year end, when you start preparing to file your tax return. In truth, the whole year is important. And right now, with the arrival of spring and the year well underway, it is a perfect time to adjust objectives set a few months ago—and really get rolling. Contact us for help. © 2019 Thomson Reuters

Think about other insurance, too. Perhaps your home has increased in value, necessitating a corresponding increase 77

the Analyst Volume 27 Number 2

Business Notes

State of the Healthcare Industry, March 2020

By Josh Estelle, Owner/Account Executive with Pfenninger, Claxton & Estelle Insurance Group For most business that offer a comprehensive suite of employee benefits that includes a medical plan, this expense is often the second largest line item on their income statement behind payroll. In addition, for those businesses that purchase a traditional, fully insured health plan and “just renew it each year,” it is probably also the expense on the profit/loss statement that is growing at the fastest rate. According to the Kaiser Family Foundation, the average family premium on an employer plan grew to $20,576. Since 2010, employer health premiums have increased 54%. That number in and of itself would be astounding, but when you combine it with the fact that over that time, those same plans have also raised deductibles and out of pocket to employees by 162% (which when raised in the same year obviously lowers premiums), it’s hard to imagine this trajectory being sustainable in the long term. Over a period where worker’s wages and overall inflation was around 20%, why are premiums rising 54% and out of pocket expenses on plans going up 162%? What, if anything, can we do about?

Let’s start by breaking down each segment of the market and where employers of different sizes may fit within each segment. Much of this information will be general and largely true across the country, but with the disclaimer that there are nuances in some states where the state does have the ability to determine certain aspects of the law.

In most states, small group health insurance is defined as employers who have 50 or fewer full-time equivalent employees. In those same states, large group is defined as employers with 51 or more FTEs. In a few states, the cutoff for large group is 100 instead of 50. For true fully insured plans in the small group market, they are governed by strict ACA requirements and must follow Community Rating Rules, which means every group gets equivalent rates regardless of health conditions or other factors besides the allowance of differentiation based on the group location (hence the term community rating; the cost of care locally can be figured into the rates). Other than that location difference, every group that applies for coverage gets the same rates without answering any medical questions and without regard for any other 78

factor. In the large group market in most states, medical underwriting is still involved and is the main factor in pricing and eligibility for large employers in the fully insured market. Fully insured plans work in this way: the employer pays the premium, and in exchange for that premium, the insurer pays claims that are eligible under the contract. In those plans, the employer has little input on what is covered, how the plans work, etc. They are given a set of plans to choose from, and they pick from that set of pre-built plans.

With the advent of the ACA Community Rated plans, we saw an influx of alternative funded plans come into the large and small group space to give options to employers who didn’t find the ACA platform attractive. In Indiana, for instance, a healthy group at the time of ACA introduction was looking at a potential 70–75% premium difference between a competitively underwritten plan and the ACA option. Because partially self-funded plans are exempt from the ACA Community Rating rules, these plans allowed groups with average or above average health to get much more competitive premiums in both the small and large group market. In some cases, it also allows them to get a partial refund of premium at the end of the year if the group has good claims experience. Many of these plans were already in the marketplace but had requirements of 20–25 employees insured to be eligible. With the ACA changes, we saw many of these alternatives move down market to allow even groups of two to have a level funded, ACA Community Rated alternative.

It has been proven statistically that employers and brokers who properly and aggressively manage selffunded and partially self-funded health plans pay less healthcare cost and that costs increase at a much slower pace than those in the fully insured market. The treatment of catastrophic chronic conditions along with prescription drug pricing have made the market more volatile than ever. The answer to the original question “what, if anything, can we do about these rising costs” is this: We can control costs more efficiently by unbundling every aspect of the health plan, analyzing each of those,

the Analyst Volume 27 Number 2

Bulk 2020.pdf 1 4/23/2020 3:56:54 PM

Business Notes continued

and placing cost control measures within the plan that minimally impact employees but significantly reduce plan costs and transparency within the plan.

BULK SYSTEMS, INC.

The first and most critical step in this process is to find a broker who is well-versed and an expert in this space. The broker needs to not only have knowledge of all the players in the insurance market, but also be aligned with the right cost containment partners. They must have the knowledge of how to implement those measures both internally in their office and externally through partnerships with vendors that manage expenses daily, like pharmacy benefit managers, care management vendors, and many more. I know many small to mid-sized employers think the term “self-funding” is scary and that they aren’t large enough to be in that space, but when properly implemented and managed by the right partners, not only is partially selffunding the least volatile method of paying for health care, it is proven to be the method that reduces the annual increase in costs more than any other means of funding your employer paid health plan.

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I had this information written and planned to close with the thought that I would expect fully insured premiums to continue to see double digit increases and ACA Community Rated plans to see even more volatility. Catastrophic medical conditions will continue to have skyrocketing costs, and the pharmaceutical side of treating these chronic conditions will continue to drive costs. When many of the drugs in the FDA approval pipeline are more than $1 million annually, it is impossible for this to not be a huge factor. Since preparation of the rough draft of this article, the COVID-19 situation has escalated significantly. It is yet to be determined what impact this might have on the benefit market, but Kaiser projects the average American who has to be treated more seriously will have expenses in excess of $20,000. We know antivirals related to COVID-19 will be introduced, the economy will be impacted, and probably things that are impossible to predict will be fallout in the benefits space from the virus. One thing is certain: this will continue to be a front that is challenging for employers to manage cost. It will be critical that they pick partners in this space to help them navigate these difficult times ahead.

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Josh Estelle is an owner/account executive with Pfenninger, Claxton & Estelle Insurance Group. He can be reached at (765) 529-6400 or josh@pceinsure.com.

79

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T.U.T.O.R.

Technical Updates, Tips, or Reviews

Keys to Successful EDI Operation and Maintenance

By Wes Byrne, Purewatercloud LLC A prior tutorial article, “What Is Electrodeionization (EDI)?” (the Analyst, Fall 2019), explains how EDI works and provides an introduction on how to apply the technology to a high-purity water treatment system. This article continues that discussion and addresses how to operate the EDI as well as how to monitor and maintain its performance.

A critical point in the prior article is that EDI is able to produce high-purity water when provided with sufficiently purified inlet water. The water must be free of suspended solids, and its concentration of dissolved organics and salts has to be reduced for normal water sources. It must typically have less than 20 microsiemens per centimeter (µS/cm) conductivity and contain a low concentration of dissolved carbon dioxide, hardness, and dissolved silica. Because the requirements of EDI models will vary, it is important to follow the guidelines provided by the manufacturer.

How these guidelines are met will depend on the quality of the raw water but generally will necessitate the use of at least single-pass reverse osmosis (RO) (1) upstream. With some water systems, a softener may be included as pretreatment to the RO since its inclusion will further reduce the concentration of hardness in the RO permeate while also preventing RO scale formation and reducing its fouling by suspended solids. If the raw water contains a particularly high concentration of dissolved salts or silica, two-pass RO may be needed or desired upstream to better protect the EDI from scale formation, or to improve its effluent quality and system reliability. Putting the water through a second pass of RO membrane will remove most of the salts that might

get through the first pass, which may be critical if there is a problem with the first-pass RO.

EDI Effluent Quality

If the water application requires better than 17.5 megohm-cm resistivity (2) quality water (less than 0.057 µS/cm), the ability of the EDI modules to consistently provide this water quality will directly depend on the modules receiving pretreated feedwater with sufficiently reduced concentrations of salts and dissolved gases like carbon dioxide or ammonia. The specific water quality requirements are dependent on the EDI model. As the inlet concentrations are reduced, the EDI effluent quality will improve relative to the electrical current flow. This would also be true when attempting to achieve part-perbillion (ppb) concentrations of dissolved silica or boron.

If the EDI system should shut down, ions will diffuse from regions of high concentration within the modules to regions of lower concentration, the extent dependent on how long the EDI is offline. When the system is put back into service, it will take operating time before its effluent quality is fully restored to pre-shutdown concentrations.

The ion exchange (IX) resin/media near the effluent end of the modules may have to electrically regenerate off ions that migrated into those regions while offline.

It is common for EDI system manufacturers to include an effluent diversion system to either dump poor quality product water or return it to an upstream location in the water system as based on an unacceptable conductivity/ resistivity reading. This system will divert water when starting up after a shutdown until it regenerates sufficiently so as to produce acceptable water. This is illustrated on the right side of Figure 1.

“It is common for EDI system manufacturers to include an effluent diversion system to either dump poor quality product water or return it to an upstream location in the water system as based on an unacceptable conductivity/resistivity reading.”

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the Analyst Volume 27 Number 2

T.U.T.O.R. continued

Figure 1: EDI system with two-pass RO upstream.

If the EDI frequently cycles, its water production will be reduced. If a break tank is located immediately upstream, then diverting the poor-quality product water back to this tank would reduce the demand on the RO and other upstream processes while reducing the time for the EDI to regenerate itself back to quality. This arrangement, however, may allow additional carbon dioxide to potentially be absorbed into the break tank water from the atmosphere unless the tank has a nitrogen blanket. As discussed in the prior article, the carbon dioxide and resulting bicarbonate ion may overwhelm the EDI if the RO permeate water pH is not consistently controlled within the range of 8.0 to 8.5. An RO/EDI system with a break tank is shown in Figure 2.

Figure 2: RO and EDI system that includes a break tank.

A common product water recovery range for an EDI system is 90% to 95%. Because the EDI concentrate outlet stream is typically of better quality than the raw water, it is often recycled back to an upstream location in the water purification system, or it is reused in some other manner. Some EDI manufacturers isolate the electrode outlet stream so that it can be sent to drain. It likely contains chlorine as well as hydrogen and oxygen gases. Other manufacturers may combine it with the concentrate outlet water, which means that the chlorine will need to be broken down before the water can safely enter an RO system.

Increased water quality and system reliability would be achieved if the EDI system was followed with mixed-bed IX tanks, especially if they contain unregenerated resins (3). This polishing system would remove most of the residual salts able to get through an upstream EDI and would have the ability to provide high-purity water, even with moderately high-salinity inlet water. So, if there is a major problem with the system RO unit, the mixed-beds 81

might temporarily allow the continued production of acceptable-quality effluent water, while the EDI would need to be taken offline to prevent it from severe scale formation.

When the RO and EDI are performing as designed, there would be minimal loading on a polishing mixed-bed system. Its resin would be expected to last a year or more before needing to be replaced.

Operational Settings

The previous article introduced the concepts of operating the EDI system with moderate flow and electrical settings. It is easy to understand that higher flowrates result in more dissolved salts that have to be removed by the EDI to meet effluent quality standards. This then requires greater current passage, which means more water splitting. More water splitting creates more hydroxide ions (OH-) that increase the potential for forming scale and possibly causing electrode corrosion.

the Analyst Volume 27 Number 2

T.U.T.O.R. continued

The EDI manufacturers will also provide minimum flow guidelines to make sure there is sufficient agitation as water flows through every EDI chamber. With EDI systems that include a large number of parallel stacks/ modules, maintaining sufficient flow becomes more critical. Fouling or scale formation in some of the chambers will elevate the pressure differential across the entire system. The extent of the increase is dampened by the number of stacks, such that flow can more easily bypass the problematic chambers in larger systems. This can lead to increased heating of plastic components within the stagnant regions, which can result in catastrophic system failure if the plastics should melt.

Advances in EDI technology have simplified the ability to operate and control EDI systems. The original EDI stacks were burdened with the need to recycle part of their concentrate stream in order to achieve higher water recovery percentages, and often needed the injection of additional dissolved salt to reduce the electrical resistance in the concentrate chambers.

A remaining complication with many EDI systems is the need to set control valves so that the dilute/product chamber pressures are slightly greater than the corresponding concentrate chamber pressure as the water streams flow through the stack. This ensures that a mechanical leak between chambers does not result in concentrate water entering the dilute/product chambers, which can reduce EDI effluent quality. Pressures and flowrates may change as the EDI operates, so occasional valve adjustments may be needed. Figure 3 shows control valve gauges with an EDI system.

Figure 3: Dilute chamber pressures must be somewhat greater than their locally associated concentrate chamber pressures.

The IX beads/media within the dilute chambers may swell as they achieve a higher regenerative state via water splitting over time. This can cause the pressure difference/drop through the dilute chamber to increase, resulting in its outlet pressure falling below the concentrate chamber outlet pressure, which may cause the effluent quality to decline. Correcting this situation for many EDI systems can be accomplished by first slightly opening the concentrate outlet valve to reduce its outlet pressure, and then closing the concentrate inlet valve as needed to obtain the correct concentrate flowrate.

With some EDI rectifiers, the voltage difference between electrodes can be adjusted. With others, the current is adjustable. Some will shift between voltage and current control, depending on the range of the setting. Without exceeding the manufacturerâ&#x20AC;&#x2122;s guidelines, the voltage/ current should be slowly adjusted upward until achieving the desired EDI product quality, keeping in mind that it may take hours before the EDI effluent quality approaches a stable value. With previously cleaned or new EDI stacks, the resins will be in an exhausted state and so will need to electrically regenerate via internal water splitting before they will be able to produce water of their anticipated quality. Operating the EDI with more current than is necessary to achieve the desired effluent quality increases the potential for scale formation within its concentrate chambers.

Monitoring

To be able to determine how well an EDI stack is performing, such as whether it is fouling or scaling, the water temperature, flowrates, voltage, current, and inlet and outlet stream pressures should be recorded and monitored. The inlet and outlet pressure differentials between the concentrate and dilute streams can be calculated to verify that the dilute stream is at a higher pressure and that the difference is within the manufacturerâ&#x20AC;&#x2122;s guidelines. The concentrate and dilute chamber pressure drops/differentials can also be calculated. It is recommended that these values be collected at least daily for in-service EDI systems.

Individual stacks may have separate flowrate control valves and flow sensors and can be individually monitored, or a number of stacks may be plumbed for parallel operation using combined stream control valves and sensors. The electrical control may also be set up for

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the Analyst Volume 27 Number 2

T.U.T.O.R. continued

“To be able to determine how well an EDI stack is performing … the water temperature, flowrates, voltage, current, and inlet and outlet stream pressures should be recorded and monitored.” individual stacks, or the electrodes of a number of stacks may be wired to operate with the same voltage differential. The current may be monitored or controlled for individual stacks, or for parallel operation of a number of stacks. In some cases, two stacks may be wired for series operation, where a cathode is electrically connected to an anode of another stack. It is important to know how the EDI system is wired in order to properly calculate and monitor the electrical resistance and power consumption of the stacks. Table A identifies useful parameters for monitoring and trending an EDI system’s performance.

Table A: Parameters That Are Useful in Monitoring and Trending EDI Performance Parameter/Variable

Justification

Inlet conductivity

To calculate the ionic loading.

Inlet CO2 (if the inlet pH is less than 8.3)

To calculate the ionic loading (if anion limited).

Inlet pH

To calculate the ionic loading (if cation limited).

Inlet dissolved silica

To calculate the ionic loading (if anion limited).

Effluent water resistivity/ conductivity

To trend the contaminant removal ability.

Effluent water dissolved silica (see Author’s Endnote 4)

To evaluate removal of lowpolarity contaminants.

Concentrate chamber pressure drop

To trend fouling/scale formation.

Dilute chamber pressure drop

To trend fouling or the state of resin regeneration.

Electrical resistance (voltage/ current)

To trend the potential for fouling/scale formation.

% Electrical efficiency

To track the extent of water splitting.

Fouling by biological materials within the concentrate chambers, or occasionally within the dilute/product chambers, will create restriction to flow that may cause the chamber pressure drop/differential to increase.

Scale formation in the concentrate chambers will have a similar effect. Both of these problems may cause the electrical resistance to increase across the stack.

Trending electrical resistance and chamber pressure drops will make it possible to evaluate ongoing EDI performance. The relative change in these variables can be used to gauge whether cleaning is needed, and after 83

the cleaning, whether original performance was fully restored.

Flowrates and water temperature will also affect these variables. Electrical resistance will decline more than 2% for every degree (°C) increase in water temperature.

Temperature can also affect the chamber inlet-to-outlet pressure drops, as related to its effect on the water viscosity. Resistance and chamber pressure drops should be normalized to standard conditions in order to more accurately trend performance changes. Pressure drops can be divided by the appropriate value to compensate for the effect of varying temperatures.

An EDI system must be operated with sufficient electrical current to create the internal water splitting that is needed to keep the IX media regenerated in the effluent end of its dilute chambers. This requires providing more current than what would otherwise be needed to ionize the dissolved gases and dissolved silica, in addition to the current needed to move all of these residual ions out of the dilute chambers via electrodialysis-driven migration.

A convenient way to estimate this base demand on electrical current is to calculate an EDI inlet Feed Conductivity Equivalent (FCE) (5). This EDI loading would be calculated using the anionic contaminants when their removal demand exceeds that of the cations, a condition known as being anion-limited. This would typically be the case when the inlet water pH is less than 8.3 because of the presence of carbon dioxide and dissolved silica, which are both removed as anions.

The FCE value would then be calculated as shown in Equation 1: FCE = Conductivity + (2.7 x mg/L-Carbon Dioxide) + (1.9 x mg/L-Dissolved Silica) Eq. 1 Some water sources (6) may contain a high concentration of ammonia with a pH greater than 8.3, where the cation loading may exceed the anion loading (i.e., cation limited). The greatest FCE demand might then be calculated as illustrated in Equation 2: the Analyst Volume 27 Number 2

T.U.T.O.R. continued

FCE = Conductivity + (6.9 x mg/L-Ammonia)

Eq. 2

The higher value from these two equations can then be inserted into Equation 3 to estimate the percentage of the total electrical current required for the ionization and ion movement. % efficiency = 5 x Product Flowrate x FCE/(Number of Cells x Current) Eq. 3 Where: “Product Flowrate” is expressed in gallons per minute.

Cleaning

Chemically cleaning an EDI is somewhat similar to cleaning an RO, but there may be unique guidelines offered by the manufacturer that should be followed.

Acidic or alkaline cleaning solutions (diluted into purified water) are pumped through the system chambers, typically at a flowrate comparable to the EDI service flow and preferably at an elevated temperature. The EDI power must be disengaged. The solution may be allowed to soak within the EDI chambers for an extended period of time, or it may be circulated back to the cleaning tank.

Figure 4 shows an example of an EDI cleaning system.

Figure 4: Circulated EDI cleaning system.

“FCE” is the higher calculated value for the Feed Conductivity Equivalent.

“Number of Cells” is the EDI unit’s quantity of dilute chambers per stack.

“Current” through the stack is expressed as amps.

While efficiency is a commonly applied term in other applications to desirable attributes, an EDI requires operation at a low electrical efficiency to achieve higher purity effluent water. The “inefficiency” is due to excess splitting of water molecules, which is needed to obtain the internal pH extremes for ionizing poorly charged contaminants. When targeting effluent water with a high resistivity, such as 15 megohm-cm or better (less than 0.067 µS/cm conductivity), it is common to operate an EDI with efficiencies as low as 10%. Monitoring the % electrical efficiency is valuable because of this relationship with effluent water quality.

EDI effluent boron or dissolved silica may serve as indicators of the system’s ability to remove poorly charged contaminants, as well as being critical water contaminants in certain applications. An increasing effluent boron/silica concentration while maintaining the same electrical efficiency and normalized chamber pressure drops may serve as evidence that the EDI’s anionic components are starting to lose their strong-base functionality due to age or exposure to oxidizing agents.

84

Cleaning before there is a substantial increase in either the concentrate chamber pressure drop or in the stack electrical resistance, normalized for any changes in flowrate, salinity, or water temperature, will increase the probability that EDI performance will be fully restored.

A maximum increase of 15% is suggested for these performance variables before cleaning (7).

EDI components offer the advantage of greater tolerance to pH extremes than an RO membrane. Surfactants or chelating agents may not be needed in the EDI cleaning solutions because much higher acid or caustic chemical concentrations can be used. Without surfactants, the rinse-up time required to restore effluent water quality may be reduced. Some EDI designs may allow the dilute/product chambers to be isolated from direct exposure to the cleaning solution, which will also reduce rinse-up and regeneration time.

A common practice is to clean the EDI first with a strongly acidic solution if any metals or scale are thought to be present. The excess acid is then rinsed out (8). A caustic cleaning step may then follow if fouling by biological or other organic materials is suspected.

Before any caustic cleaning step, a sodium chloride the Analyst Volume 27 Number 2

T.U.T.O.R. continued

brine solution is usually passed through the EDI to either exchange sodium ions for the hydrogen ions on the cation resin if previously acid-cleaned, or to displace hardness ions if not. A strongly caustic solution, or possibly a combined caustic and salt solution, is then pumped into the EDI. After rinsing, some manufacturers will require another brine step to fully exhaust the resin.

The extent of final rinsing may be specified before it is safe to restore power and begin regenerating the EDI resin back to its original equilibrium. Restoring original performance may take a number of hours, which can be somewhat reduced by temporarily increasing the voltage/ current setting.

Final Thought

Keep in mind that with sufficient pretreatment of the EDI feedwater, cleaning may rarely, if ever, be required.

This then means that the EDI stacks will consistently produce high-purity effluent water with minimal maintenance, other than some tweaking of flowrates and voltage/current settings.

85

Endnotes

1. In single-pass RO, water permeates the membrane only once as opposed to twice with two-pass RO. 2. Resistivity in units of megohm-cm is the reciprocal of conductivity in microsiemens/centimeter (ÂľS/cm).

3. Due to reduced shedding of contaminant ions, it is not feasible to chemically regenerate IX resin to the same level as unused/new resin.

4. If reduced dissolved silica is required for the process water.

5. A term introduced by IonPure, EDI equipment made by Evoqua Water Technologies, LLC.

6. Ammonia is present in some aquifers and will result from the breakdown of chloramines.

7. Always follow the EDI manufacturerâ&#x20AC;&#x2122;s guidelines.

8. Purified water is used for any dilution or rinsing.

Wes Byrne is president of Purewatercloud LLC. He has 40 years of RO and high-purity water treatment experience and authored the book titled Reverse Osmosis, A Practical Guide for Industrial Users (2nd edition, 2002, Tall Oaks Ventures LLC).

Purewatercloud LLC provides consulting, online training and training seminars, membrane cleaning, software development, and RO monitoring products to support the needs of RO, UF, IX, and EDI manufacturers and end users. Mr. Byrne may be reached at WesByrne@purewatercloud.com.

the Analyst Volume 27 Number 2

Advertising Index 47 AMSA, Inc.

44 Myron L. Company

49 AquaPhoenix

28 North Metal & Chemical Company

55 Bio-Source, Inc.

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41 Brenntag North America

25 QualiChem, Inc.

7

43 Sanipur US LLC

Browne Laboratories, Inc.

Pulsafeeder, Inc.

79 Bulk Systems, Inc.

86 Seko Dosing Systems Corp.

85 Chem-Met Company

88 Special Pathogens Laboratory

57 CHEMetrics

66 Uniphos

15 Environmental Safety Technologies, Inc.

19 Walchem, IWAKI America Inc.

13 IDEXX

87 Water Science Technologies

27 Lovibond Tintometer

53 WaterColor Management

51 McGowan Insurance Group

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the Analyst Volume 27 Number 2

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