Location: Major Southwest Texas Universitycisnerosresearch.com/docs/SRB Presentation.pdf · 1 SRB Project – Sulfite Reducing Bacteria Primary Chilled Water Loop . Product: WBS (Water

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SRB Project – Sulfite Reducing Bacteria Primary Chilled Water Loop

Product: WBS (Water Bacteria Solution)

Location: Major Southwest Texas University

Cisne Enterprises, Inc. Purely Elemental

Mr. Assistant Director Assistant Director Plant Operations/HVAC Nov 2.2009 Reference: SRB Contract ________Campus Mr. The treatment program was begun on October the 16th 2009. Injection points were selected on the University campus: Kelly Hall, Miners Village and Satellite Plant. The method of monitoring has been by ATP. ATP testing provides a rapid method for the detection of all living cells in the water as well as a method for determination of the biocide and bio-dispersant efficacy in a very short time period. A short time period, being the area of focus at this point. Biological plate counts are very good. They however do require on the average of two weeks for determination, due to the fact that the Bacterial Colony Forming Unit counts need to reach eye level determination before the result can be known. The method of determination by ATP is fifteen seconds and results are as real time biological monitoring. ATP analysis offers several advantages as an assay for active biomass: It can be performed in a short period of time, and it has a sensitive limit of detection. ATP is an energy cell molecule. ATP (adenosine triphosphate) A nucleotide that is of fundamental importance as a carrier of chemical energy in all living organisms. It consists of adenine linked to D-ribose (i.e. adenosine); the D-ribose component bears three phosphate groups, linearly linked together by covalent bonds. These bonds can undergo hydrolysis to yield either a molecule of ADP (adenosine diphosphate) and inorganic phosphate or a molecule of AMP. Both these reactions yield a large amount of energy (about 30.6 kJ mol–1) that is used to power the living cell with resultant ATP determination. The standard PLATE TECHNIQUE FOR BACTERIAL ENUMERATION will be used as the program progresses. Short time SRB auger methods are being used as a rapid detection method to give an assessment of total SRB colonies after the first chemical charge has been accomplished. An initial injection is in progress to establish our treatment objectivities. Five initial monitoring locations have been selected as control points, Kelly Hall-Miners Village-Central Plant-Satellite Plant-Main Thermal Water Storage Tank are the locations established. Initial ATP in energy source units Fmol before program start 10/15/09 Date 10/13/09

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Location Central Plant Satellite Plant Miners Village Kelly Hall Main Storage Tank ATP fmol 688 287 285 206 186 SRB > 10-3 < 10-2 > 10-3 > 10-4 > 10-3 Location: Central Plant Satellite Plant Miners Village Kelly Hall Main Storage Tank Program Start Date 10/16/09 Chemical Injection start up. Reading on 10/28/09 ATP 12 10 8 7 16 SRB < 10-3 < 10-1 10-3 < 10-3 > 10-3 Guidelines SRB 10-3 CFU = 1000 colonies ATP Less than 20 is considered very good for aerobic and non aerobic bacteria bio mass this may not include all SRB or NRB types of bacteria, rapid test cultures are used for quick determination. The next phase of monitoring will be a more definitive quantification for SRB CFU, conjunctive with ATP fmol energy units. Injection is scheduled to begin directly into the thermal storage tank. This will be followed by a system drain down and recharge of biocide into the systems. The units will be tested for biomass and direct injection will start on a localized basis in units found to be contaminated. Additional recirculation of some units may be required, so as to remove larger biomass concentrations should they be found. Definitive reports will be forthcoming, it would be somewhat misleading to list reduction percentages and or pass/fail locations at this time, based upon a two week start up time. As more information becomes collected, it will offer an objective evaluation of the progress being made. Thank You

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Summary Primary Chilled Water Loop

The Problem: Infected water with SRB

Reason: Contaminated water in the chilled water loop.

Time Line:

Step #1: Injection Time 14 days 2 week Treatment

Step #2: Application Time 60 days Two Months Application Time

Step # 3: Maintenance Flush 30 days Monthly System Cleaning

Step # 4: Shock Time 365 days One Year Projected efficacy time to disinfect the water in Chilled Water

Conclusion: Diminish the SRB problem in the system, reducing the overall repair and replacement problems to HVAC department.

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THE PROBLEM is that the chilled water loop has developed Sulfite Reducing Bacteria (SRB) problem. This problem was determined with field testing and an in-depth analysis by an independent metallurgy laboratory, specializing in these types of problems, made it possible for us to concentrate in a more refined area of the problem. This project outline comes as a result of those findings. Chemical selection for this type of problem becomes complex. Primarily in regard to the environmental issues involved with the treatment of four million gallons of water at a major university campus. The purpose of the prolonged treatment exposure time is to avoid the protein excretion from the bacteria. When a quick rupture of the cell membrane wall occurs the cell attempts to avoid intrusion via this excretion method, further compounding the problem. By applying a differential charge across the cell wall it will slowly lose its permeability without the protective filming, which might otherwise occur from the bacteria. This is accomplished by the highly cationic charge, imparted by the treatment process, allowing the unit to lose the nutrients necessary to sustain life. The bacteria have been present a long time and have the ability to live and thrive under many and varied conditions. Our job is to “out smart” the cell during the treatment process in order to have successful elimination. The surfactant properties of the material being used will assist us in maintaining the fluid of the dead cells. This maintains the cells in the water phase, allowing removal through the system bleed. Outlined below is the method that will be used for biological growth, Adenosine Triphosphate (ATP). The use of firefly luciferase to assay adenosine triphosphate (ATP) extracted from microorganisms provides an easy means to enumerate microbes within minutes. The small amount of light produced is proportional to ATP and thus microbial number. The average bacterium contains around 10(-15) g ATP per cell. Present reagents permit detection of 10(3) cells per tube. Luminometers currently on the market detect about 10(-12) g ATP. Proper extraction of ATP from the microbes is an essential part of any protocol, as is the removal of non-microbial ATP from, for example, somatic cells also present in samples. The technique may be applied to a wide range of samples, for example food and beverages and clinical samples such as urine. The ATP assay gives a global measure of microbial numbers. This test is a cell biomarker and is considered the Gold standard in Bio testing. By applying the treatment as outlined and using ATP, the problem can be controlled, eliminating future issues and concerns.

Primary Chilled Water Loop

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Is Something in Your Water ?

Example of SRB Determination of Potential SRB Population - observe daily for reaction. Date of Test: 01-12-09 thru 02-12-09 / Sample taken from: Kelly Hall / Chemical: WBS

SRB Test showing (+) Positive. Treated sample

The treatment being used will rupture the cell wall of the bacteria and accelerate the loss of cell nutrients resulting in the extinction of the cell. For this to occur, some resident contact time will be required as the chemical imparts a cationic charge to the cell wall, resulting in the parting of the protein structure and allowing for the loss of the required food sourcing occurring. Based on laboratory observations, this treatment will be effective for the systems considered for treatment.

Page 4 of 9


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Reason

The reason for this type of treatment will be to provide protection for the HAVC system and associated equipment. Without this treatment program the SRB bacteria will continue to cause a serious problem. The treatment is costly due to the complexity of the bacteria as well as the chemistry related to achieving a resolution. Environmentally safe micro biocides are more expensive than others, which could be used if environmental exposure were not a concern. How does SRB occur? Sulfate-reducing bacteria (SRB) form one group of sulfate reducing prokaryotes. Main genus is Desulfovibrio. Desulfovibrio desulfuricans is often used to immobilize dissolved heavy metals as metallic sulfides. Beijerinck[1] showed in 1895 that living matter could reduce sulphate to sulphide in sediments under anaerobic conditions. Although many bacteria can produce sulphide, only a few do so at a sufficient rate for application in high-rate processes. These rapid sulphide-generating bacteria are able to conserve energy by the reduction of sulfur oxyanions[2], and they are generally termed sulphate-reducing bacteria (SRB). A typical overall conversion equation is (neglecting the small amount of organic material required to produce biomass): SO42- + CH3COOH + 2 H+ → HS- + 2 HCO3- + 3 H+ (1) Eight electrons are transferred from the energy source acetic acid to the electron acceptor sulphate in order to produce sulphide. The reaction equation shows that in the same process also alkalinity is produced. This leads to an increase in the pH of the water, often to a near neutral value. Typically, a certain amount of metals is present together with the sulfate. These metals will react with the dissolved sulfide to form highly insoluble metals sulfides. HS- + Me2+ → MeS + H+ (2) Me2+ can for example be copper, zinc etc.


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K. Purdy (University of Essex, UK). Environmental isolates from Alaska and Indonesia were kindly provided by Dr I. B. Beech (University of Portsmouth, UK; see Zinkevich et al., 1996Down ). All the SRB used in this work used lactate as a carbon and energy source and were routinely cultured in SL10-lactate media at pH 7·0, in either 10 ml volumes in 12 ml Hach tubes (screw-top test tubes with an airtight seal) or 50 ml volumes in 60 ml Weaten vials. SL10 defined liquid media (Widdel & Pfennig, 1981Down ) contained the salts (g l-1) Na2SO4 (4·0), KH2PO4 (0·2), NH4Cl (0·25), NaCl (1·0), MgCl2 . 6H2O (0·4), KCl (0·5) and CaCl2 (0·15) with trace elements and vitamins (μg l-1) MnCl2 . 4H2O (100), CoCl2 . 6H2O (190), ZnSO4 . 7H2O (144), H3BO3 (6), NiCl2 . 6H2O (24), CuCl2 . 2H2O (2), NaMoO4 . 2H2O (36), FeSO4 . 7H2O (2·1), Na2SeO3 . 5H2O (6), Na2WO4 . 2H2O (8); (μg l-1) 4-aminobenzoic acid (0·4), D(+)-biotin (0·1), nicotinic acid (1·0), Ca-D(+)-pantothenate (0·5), pyridoxine . 2HCl (1·5) and thiamin . 2HCl (1·0). The media also contained 1·5 mM sodium sulphide and 20 mM sodium lactate, in order to lower the redox potential of the medium and act as a carbon source. Cultures were incubated at 30 °C in the dark and samples of spent media for analysis were filtered through 0·45 μm pore size cellulose nitrate membranes which effectively remove cells (control). Experiment showed that protein concentrations in filtered plant medium were negligible), snap-frozen in liquid nitrogen and stored at -20 Deg.C.


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Step #1: Injection Time 14 days 2 week Treatment

Step #2: Treatment 60 days Two Months Application Time

Step # 3: Maintenance Flush 30 days Monthly System Cleaning

Step # 4: Application Time 365 days One Year Projected efficacy time to disinfect the water in Chilled Water

Timeline: Primary Chilled Water Loop

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Polarographic measurement of metal binding by SRB spent medium. Differential pulse polarography was carried out using a Metrohm 663 VA stand incorporating a multiwavelength electrode set to the static mercury drop electrode facility. The analysis was carried out using Autolab General Purpose Electrochemical System (GPES) for Windows, version 4.3 (Ecochemie, The Netherlands). Measurements of free metal ion concentrations were carried out in 25 ml electrolyte containing 1 M KCl, buffered with either 10 mM PIPES (pH 6·0) or 50 mM MES (pH 5·5) buffer, adjusted to the appropriate pH value using tetramethylammonium hydroxide. These buffers were chosen for their negligible metal-binding activities (Good et al., 1986Down ). In most experiments, free metal cation concentrations, from added metal chloride solutions, were measured immediately after the reaction mixture was purged with N2. The electrolyte was purged for 180 s and the current measured over three scans between potentials of 0 and -0·4 V for copper or -0·8 and -1·2 V for zinc with a step potential of 0·0036 V. Each metal has a characteristic half wave potential, -0·18 V for copper and -0·97 V for zinc, with the measured current being proportional to the amount of metal ion present. Free metal concentrations were calculated with respect to a standard curve over the range 10–100 μM. Two approaches were used to measure the metal-binding activity present in SRB culture filtrates. The first involved measuring the decrease in free metal concentration on the addition of a known volume of sample and calculating the concentration of metal-binding compound as the amount of metal bound (ml culture filtrate)-1 (Shuman, 1994Down ). This method was used to measure the increase in metal-binding activity over time in Dc. multivorans batch cultures and to identify which HPLC fractions contained metalbinding activity. The second approach (the reverse of the method described above) involved the addition of aliquots of metal ion solution to buffered culture filtrate. These titration data could then be transformed using the method of Ruzic (1982)Down and van den Berg (1982)Down to obtain stability constants for the metal-binding ligands.


CONCLUSION

The SRB project at the University campus is extremely important for the campus HVAC systems to continue to meet operational status goals as well as meet our established energy conservation objectivities. The problem began showing up several years ago and efforts were started to resolve The problem. This problem may be unusual for these types of systems, however, not uncommon. It is our professional opinion that this problem has been in existence, Needs to be addressed and resolved with urgency. Maintenance cost to unit replacement ratio and energy savings is some of the many Reasons this problem must reach a resolution this year. The labor cost and expenses And inconveniences incurred during “down times” will continue unless corrective Action is taken. The goals are to resolve and bring this ongoing and expensive current situation under control this year, preventing a reoccurrence in the future which such a project is one that other Universities and large buildings with similar systems can strive to emulate.

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Corrosion Testing Laboratories, Inc. 60 Blue Hen Drive, Newark, DE USA 19713

(302) 454-8200 • fax (302) 454-8204 • e-mail: [email protected] http://www.corrosionlab.com

FAILURE ANALYSIS OF ALUMINUM-FIN/COPPER TUBE

HORIZONTAL BASIC FAN COIL CUSTOMER: NORMEX INTERNATIONAL LABORATORIES

CTL PROJECT NO.: 25137

Mr. _________________ provided the background information on the submitted samples, which was relied upon to assess the samples supplied, and assisted in the development of opinion. A Model number HBR04-D-2-B Titus Horizontal Basic Fan Coil (HBFC) unit failed when leaks occurred in the copper tubing. The HBFC unit (tag number FCU-B) was used for comfort cooling on the third floor of Kelly Hall (phase 2B). The unit was in service from 06-06-06 to 05-13-08. Water flowed through the ID (inside surface) of the tubes while residential space return air was on the OD surface (outside surface). Water at a flow rate of 1.00 GPM (gallons per minute) entered and exited the copper coil tubes at approximately 45°F and 59°F. Normal operating pressure of the unit was 60psi. Fan assisted airflow rate over the unit was 323.00 CFM (cubic feet per minute). The failure was not isolated; several similar units throughout the building had failed. The failed units were all secondary type units that went through an idle period over the winter months (roughly from November until late March). There were no reported problems in units that had continuous water flow throughout the whole year. The total air-cooling closed system for the building was about 3.8 million gallons of water that was supplied from one (1) large tank. The municipal water was used as make-up water when needed. The systems cooling water was poorly filtered and that the hardness was measured around 90ppm, moderately hard on the water hardness scale. It was reported that higher than normal oxygen levels were present in the water along with iron levels tested at greater than 3ppm. The cooling water was treated with an all-organic chemical system by a third party vendor. No additional information on the water treatment product(s) such as name, chemistry or function/purpose (i.e., inhibition of corrosion, scale and deposit, fouling, and/or microbiological growth) were provided. The coil was sent to CTL for evaluation, Figure 1. Inspection of the coil, out of the box, revealed damage to the brazed joint on the end (front-end) of the coil with the inlet and outlet supply water lines, Figure 2. The damage prevented CTL from performing a pressure check of the unit; subsequently the general locations of any leaks could not be established. It was reported that one leak was located on one of the U-shaped sections of tube (U-bend) on the back-end (side Opposite the inlet/outlet lines) of the HBFC.

http://www.corrosionlab.com/

Corrosion Testing Laboratories, Inc. (CTL)

Figure 1. As-received front-end view (water inlet and outlet lines) and back-end view of aluminum-finned/copper tube HBFC unit.

Figure 2. Broken connection found on front-end (side with water inlet and outlet lines) of HBFC during initial inspection when unit was received

September 2008

Corrosion Testing Laboratories, Inc. (CTL) FINDINGS: Chemical Analysis (water) During the initial inspection of the HBFC unit, it was discovered that a considerable amount of water was present in the copper tubes. Ion Chromatography (IC) was performed on a sample of the coil water. Significant (>100ppm) concentrations of chloride and sulfate along with lesser amounts of acetate, formate, nitrite, nitrate, and phosphate were detected in the water sample, Table 1.

September 2008

Table 1: IC Analysis (concentration) of Sample of Water Found Inside The Coil

Ions Flouride Acetate Formate Chloride Nitrite Nitrate Phosphate Sulfate ppm 0.976 3.034 8.604 169.82 1.877 6.217 5.484 134.18

Visual (Macro) Examination A sizable through-wall hole was found on one of the U-bends located on the back end of the HBFC during visual inspection, Figures 3, 4. The U-bend was removed from the unit after which the ID surface was visually examined through the openings on either end. Scale and deposit buildup were observed along with either a greenish colored gelatinous type mound or a slime film covered solid scale/deposit buildup (tubercle) that was positioned over the through-wall hole, Figure 5.

Figure 3. Back-end of HBFC unit showing location

of U-bend with through-wall hole. Figure 4. Close-up of U-bend with through-wall hole indicated by arrow. Greenish colored corrosion product can be seen in and around hole.


Figure 5. Gelatinous mound or slime film covered tubercle found positioned over the through-wall hole in the U-bend section of tube. Scale and deposit buildup were also observed. 12X original magnification.

Five straight sections of tube were randomly chosen and removed from the finned section of the HBFC unit. The fins were subsequently removed from the copper tubes sections after which there OD surfaces were cleaned. Examination of the tubes OD surfaces with the stereomicroscope (magnification 100X) revealed multiple through-wall holes on four out of the five tubes. Scale, deposits, and/ or corrosion product buildup could be seen on the interior (ID) surface of the tubes through the end openings. The straight sections of tubes were sectioned longitudinally. A sizable portion of the straight tube sample’s ID surface was covered with a myriad of scale, deposits, and corrosion product along with tubercles or mound like formations, and gelatinous (slime) film, Figure 6. There was some gravitational effect with one portion of the tubes having a heavier concentration of the scale and deposit buildup but the mound-like formations along with the gelatinous film were found on the sides of the (270 degrees) sampled straight sections of tube in addition to the bottom. Upon closer inspection, it was determined that the mound formations were both solid and gelatinous. The solid formations (tubercles) were made up of a black outer crust with a green/blue inner solid material (deposit/corrosion product), Figures 7, 8. Pits were found under the tubercles. Gray and black colored gelatinous type mound formations were also discovered on the tubes ID surface. The gray colored mounds were larger and found to be fairly dried out. Larger sized pits, some through-wall, were found under these dried-out mound formations, Figures 9, 10. The black gelatinous mounds had the appearance of still being wet and slimy and when probed were still in the gel like state, Figure 11. In addition to the tubercles and the gelatinous mounds there was scale/deposits and slime (gel) like film found on the ID surface, Figure 12. Some of the dry scale appeared flaky and was weakly attached to the surface of the tubes, this type of scale was indicative of dried slime (bio) film/layer, Figure 13. Cleaning of the ID straight tube surfaces revealed a significant amount of varying sized pits, Figure 14,15.

September 2008


Figure 6. Representative areas from two of the straight tube half sections showing examples of scale, deposits corrosion product, mound like formations, and gelatinous type (slime) film.

Figure 7. Example of black colored solid (tubercle) formation. 20X original magnification.

Figure 8. Blue-white colored product (solids) inside black tubercle. 11X original magnification

Figure 9. Dried out gray gelatinous mound over through-wall pit. Blueish-green slime like product around mound. 16X original magnification.

Figure 10. Through-wall pit on tubes OD surface that correspond to gelatinous mound in Figure 4. 16X original magnification.

September 2008

EDS Sample #1

EDS Sample #2

EDS Sample #4

EDS Sample #3


Figure 11. Black gelatinous mound formations. 16X original magnification.

Figure 12. Deposits, scale and blue-green gelatinous (slime) film. 16X original magnification.

Figure 13. Flaky type scale (dried gelatinous/slime film). 16X original magnification.

Figure 14. Large through-wall hole/pit found under larger gelatinous mounds. Crystalline cuprous oxide in the pit. Some undercutting in pit. 16X original magnification

Figure 15. Smaller pits found under deposits, scale, and gelatinous film. 16X original magnification.

September 2008

EDS Sample #5

EDS Sample#6

EDS Sample #7

Corrosion Testing Laboratories, Inc. (CTL) Chemical Analysis (deposits/scale/mounds) Samples of the ID surface deposits/scale, solid (tubercles) and gelatinous mound formations, and the gelatinous (slime) layer were analyzed by energy dispersive x-ray spectroscopy (EDS) for elemental composition. Approximate elemental composition (weight percent) findings for the EDS samples are tabulated in Table 2. The copper was from the base metal metallurgy, while the oxygen was most likely detected as part of the metal oxide that was formed on the surface. Sulfur chloride, calcium, and iron were from the cooling water. The source of the phosphorous was unknown. It could have been from the water treatment chemicals or it could have been an indicator of biological activity. It has been reported that phosphorous-rich deposits contain active bacteria, which use phosphorous chemistry to store energy1

September 2008

Table 2: EDS ChemicAL Analysis ELEMENT Sample Sample Sample Sample Sample Sample Sample

#1 #2 #3 #4 #5 #6 #7 Oxygen M M M M M M M Silicon … … … t … t … Phosphorous m m m m t m t Sulfur t t m m … t … Chloride … … t t m t t Calcium t t … t t t … Iron m m t M m m t Copper M M M M M M M

M = major element (>10wt%), m = minor element (1 to 10wt %), t = trace element (0.2 to 1 wt%)

Sample #1: Outside surface of black mound (See Figure 8 ). Sample #2: Blue-white material/product inside black mound (See Figure 8 ). Sample #3: Material/product inside large dried gel mound over pit (see Figure 9). Sample #4: Scale/Deposits on surface (see Figure 9). Sample #5: Blue-green gelatinous/slime film (see Figure 12). Sample #6: Scale/Deposits on surface (see Figure 12 ). Sample #7: Reddish colored surface area (See Figure 12).

Metallographic (Micro) Examination Cross-sectional metallographic mounts were prepared from areas adjacent to the through-wall holes found on the U-bend section of tube and from one of the straight sections of tube examined. The polished and etched cross sections were examined via optical microscopy. Microscopic examination revealed that the through-wall holes were created by metal loss originating from the ID surface of the tubes, Figure 16, 17. Minor undercutting can be seen on the straight tube cross-section sample. The etched microstructures of the tube samples were typical for copper tubing. There were no indications of metallurgical defects observed in either of the samples’ microstructures. 1 Tatnall, R.E. and Pope, D.H., “Identification of MIC”, A Practical Manual on Microbiologically Influenced Corrosion, 1993, p67.


ID

OD

ID

OD

Figure 16. Cross section of through-wall hole on U-bend section of tube removed from the rear of HBFC unit. 50X original magnification. Potassium di-chromate etch

Figure 17y. Cross section of through-wall hole on straight section of tube removed from the finned area of HBFC unit. 50X original magnification. Potassium di-chromate etch..

DISCUSSION AND CONCLUSION: Examination of the ID surfaces of the copper tube sections pulled from the HBFC revealed a buildup of scale and deposits on the bottom portion of the tubes. The deposit build-up was most likely the result of the stagnant (no flow) service conditions caused by the reduced operation of the unit over the winter months. The deposit accumulation in the bottom portion of the tubes was due to gravitational settling of solids and minerals present in the still water. The solid (tubercles) and gelatinous mound-like formations along with the underlying pits along the ID surface of the tubes other than at the bottom (sides) required the existence of aggressive water conditions. Under such conditions, cells of copper oxide or other complexes can initiate and establish localized sites anywhere on a tubes’ ID surface. Localized electrochemical reactions can result in the formation and growth of solid (tubercles) mound like formations, which are essentially made up of accumulated corrosion product along with minerals and ionic species from the surrounding water environment. The formation and growth of the scale/mound formations (tubercles) on the surface of the tubes created conditions for localized under-deposit attack. Deposits and scale (includes corrosion product) can cause or accelerate corrosion both directly and indirectly. If deposits or scale contain corrosive species (i.e., chlorides and sulfur compounds, known to be severely aggressive to copper and copper alloys2) attack is direct; interaction with the aggressive deposit or scale causes wastage. Shielding of surfaces below deposits or scale formations produces indirect attack; corrosion occurs as a consequence of surface shielding by the deposit or scale formations. The initial driving force is often an oxygen concentration cell or metal ion cell, but continued growth is fostered by accumulation of acidic hydrolyzed salts in the crevice formed under the deposits or scale formations. Literature indicates that the presence of gelatinous type mounds and/or a gelatinous (slime) film/layer on copper tubes, in water service, could be the result of biological formation/growth. Microbially induced or influenced corrosion (MIC) occurs when microorganisms and the byproducts they produce influence the electrochemical corrosion of metals. Microbes present in the water readily attach to the copper surface and proceed to form a protective gelatinous-like or slime 2 Harvey Herro and Robert Port, The Nalco Guide to Cooling Water System Failure Analysis, p71- 85, 1993. 18


film (biofilm), which further facilitates organic decomposition. Discontinuous or localized coverage by the biofilm can create favorable conditions for corrosion initiation (localized attack). Under low flow or no flow (stagnant) conditions the biofilm can thicken (local mound like formations). The biofilm traps water, nutrients, and additional microbes along with solids, minerals, and aggressive species from the water. As the biofilm increases in thickness, oxygen permeability to the interior decreases and this creates an ideal environment for anaerobic bacteria. The remaining aerobic bacteria will consume any remaining oxygen that does not penetrate the biofilm. Corrosion occurs due to the formation of concentration cells under the biofilm. An electrochemical reaction similar to the reaction associated with under-deposit attack leads to localized metal wastage as well as pitting. The electrochemical reaction under the biofilm becomes self-sustaining. Mobile aggressive species (anions) such as chloride and sulfate readily migrate to the surface under the biofilm formations to maintain a charge balance. Concentration of these aggressive species can accelerate the corrosion process. Water quality and the extended stagnant (non-flow) period contributed to create conditions that were conducive for aggressive corrosion attack of the copper tubes in the Horizontal Basic Fan Coil (HBFC) unit. Localized metal wastage (pitting) on the ID surfaces of the copper tubes was the result of a combination of under-deposit/under-scale type corrosion attack and MIC. This study was performed, and this report prepared, based upon specific samples provided to Corrosion Testing Laboratories, Inc. [CTL] by Normex International Laboratories, Inc. The information contained in this report represents only the materials evaluated, and such work performed in accordance with CTL's Quality Assurance Manual, Revision 12, issued 23 June 2005. The conclusions and opinions were developed within a reasonable degree of scientific certainty, and based upon the materials and information provided to date. If additional information became available (i.e., after continued review of the material received, or additional material submitted for examination), we would reserve the right to alter or change our opinions. CTL assumes no responsibility for variations in sample or data quality (composition, appearance, performance, etc.) or any other feature of similar matter produced, measured, manufactured, fabricated, etc. by persons or under conditions over which we have no control. This report shall not be reproduced, except in full, without the written approval of CTL. All material that is received by CTL will be discarded six (6) months after this report has been issued, unless other arrangements have been made. All liquid, soil and gaseous samples that is received by CTL shall not be stored for more than thirty (30) days and shall be disposed of in accordance with applicable rules and regulations. Principal Investigator Reviewed By

Failure Analysis Engineer Senior Corrosion Scientist Laboratory Supervisor

September 2008

___________ _____________

SRB Biological Control 3.31.10

Test Results

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Major USA University

SRB Biological Control 3.31.10

Cultures taken monthly and retain for 12 months.

21

Indio 4.26.10

Eagle 4.26.10

Franklin 4.26.10

Test Protocol Test Used Quick Scan for SRB Determination of Sulfate reducing Bacteria Culture will turn Black within five days If SRB is above 10>3 Colonies are present.

Location Date

Del

Norte

4.22.1

0

Sacra

mento

4.22.1

0

Educa

tion

4.22.1

0

Phy.Sc

i

4.20.10

Miners

Hall 4.20.10

Cent.

Museum 4.20.10

Bio

Sci 4.20.10

Chilled Water

Sat. Plt. 4.20.10

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Equipment used at ATP Hygiena System Sure Plus SN 016475 Cal Date 5.1.10 Radio Isotope Positive Rod – Exp. Date, May 2014 Negative Rod Exp. Date May 2014 Calibration Control Kit PCO 4000 Stored at Room Temperatures

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All analysis by standard methods determination.

ATP Vials maintained at a temperature of 32 degrees F.

Laboratory instruments calibrated Monthly.

All analysis performed wearing sterile gloves and sterile masking

Radio Isotope calibration performed on ATP monthly.

Retain period of samples is 12 months


All analysis performed wearing sterile gloves and sterile masking Retain period of samples is 12 months

Summary: All cultures taken last month indicated negative for SRB. These are in retainer status for a period of 12 months.

ATP Vials maintained at a temperature of 32 degrees F. All analysis performed wering sterile gloves and sterile masking . Retain period of samples is 12 months.

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Bldg. SRB Date Cultured Date Reviewed

Cotton Mem Slight 3.2.10 3.27.10

Hudspeth Zero 3.2.10 3.27.10

Graham Zero 3.2.10 3.27.10

Liberal Arts Zero 3.2.10 3.27.10

Cent. Museum Zero 3.2.10 3.27.10

Seamon Slight 3.2.10 3.27.10

The SRB Cultures are to be reviewed after five days this review is extended so as to pick up

the slightest growth in the systems.


Kelly Zero 1.17.10 3.27.10

Kelly Zero 2.16.10 3.27.10

Hueco 10>6 11.18.09 3.27.10

Hueco Zero 12.15.09 3.27.10 Hueco Zero 1.13.10 3.27.10

Hueco Slight 2.16.10 3.27.10




Quinn Hall Zero 12.07.09 3.27.10

Bio Science Zero 12.07.09 3.27.10

Mem. Gym Zero 12.07.09 3.27.10

Worrell Hall Slight 12.23.09 3.27.10

Worrell Hall Slight 2.16.10 3.27.10


the slightest growth in the systems. 25


Bell Hall Slight 12.23.09 3.27.10

Psychology Zero 12.23.09 3.27.10

Benedict Hall Zero 12.23.09 3.27.10

ULC Zero 12.17.09 3.27.10

Cent. Museum Zero 12.23.09 3.27.10

Book Store Zero 1.11.10 3.27.10



Cultures Taken 3.25.10 Cultures after six day incubation period

Tinaja Less than 10>3 colonies

Guadalupe Less than 10>3 colonies

Sacramento Less than 10>3 colonies

Eagle Less than 10>3 colonies

Del Norte Less than 10>3 colonies

Chisos Less than 10>3 colonies

Cultures Taken 3.25.10 Cultures after six day incubation period

Hueco Less than 10>3 colonies

Indio Less than 10>3 colonies

Franklin Less than 10>3 colonies

Mimbres Less than 10>3 colonies

Davis Less than 10>3 colonies

Capitan Less than 10>3 colonies

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Major USA University – SRB Project

Comments and Summary Date: 12.31.10

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Summary All Cultures taken last month indicated neg for SRB. These are in Retainer status for a period of 12 months

All analysis by standard methods determination.


Laboratory instruments calibrated Monthly.

All analysis performed wearing sterile gloves and sterile masking

Radio Isotope calibration performed on ATP monthly.

Retain period of samples is 12 months

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SRB Cultures After five (5) day incubation - NEG

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SRB Bacteria before termination

Food Source Metal>>>>>>>>>>>

Summary 12.31.10 Effective this month, the new biocide has been placed into full usage, this will enhance the stability of the program and provide an additional corrosion protection program for the system All biological cultures are negative from the locations as sampled. Data would indicate that we move into the month of reduced circulation with the bacteria in a controlled state with some regeneration occurring, but much reduced. It would appear from the collected data that most biological cell structures are in the process of removal.

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Culture in system water BEFORE

New School of Nursing

Culture in system water AFTER Biological treatment

and flush and drain x 3 New School of Nursing

Cultures will be taken monthly

7.31.10 Monthly S.R.B. Summary Status of SRB Bacteria: While under control, it has not been completely removed Status just taken: undetermined at this time. Status 60 day cultures: Under Control Status 90 day: Some have indicated slight cell regeneration The system would indicate good control, but not as yet terminated in the complete system. This is in regard to the locations cultured at the time the culture was obtained SRB BACTERIA WAS FOUND IN THE NEW SCHOOL OF NURSING AND WAS TERMINATED AND COMPLETE REMOVAL FROM THE SYSTEM WAS ACCOMPLISHED. THIS OCCURRED FOLLOWING A RECIRCULATING PUMP OUTAGE AND PUMP REPLACEMENT. THE CULTURES WERE OBTAINED FROM THE SYSTEM FOLLOWING THE PUMP REPLACEMENT AND CULTURED WITH THE RESULTS AS SHOWN BELOW.

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MEMORANDUM

Comments – Summary

Date: January 5th. 2011

From: The Director of Plant Operations /HVAC Major USA University Subject: SRB (Sulfite Reducing Bacteria) Project The later part of 2009, we decided to try a new product to deal with the bacterium (SRB, Sulfite Reducing Bacteria problem that was causing leaks from the inside out on our chill water coils. A new product to the water treatment industry was used. The product name is WBS (Water Bacteria Solution) Here is what that product has done for us. a) WBS is an excellent biocide. It kills bacteria on contact and neutralizes acids. We use an independent laboratory to verify results of before and after CFU (Colony Forming Units) counts. b) WBS is a great cleaner for distribution systems, including thermal tanks, coils, heat exchangers, etc. The cleansing of the water side of the coils allows for optimum heat transfer, thus bringing old systems back to original heat transfer capability reducing the heat lost and the cost of it. c) WBS is friendly to the environment, as well as to personnel handling the product. d) WBS is totally soluble in water and it makes it slick (increased lubricity) a great drag reducer. This is the quality that is giving us a reduction in our total Central Plants KWG consumption, not just pumping loads. In the past nine (9) months we have consumed 6.1% less KWH as compare to last year's same time period. e) Before the treatment of our chill water system, we were replacing approx. 45 to 50 cooling coils (panels) per year with corrosion from the inside out. This was costing approx. 50K per year. This year, we have only replaced one (1) unit after the SRB bacteria was brought under control. f) We estimate the savings on electricity to be 40 to 50K per year. We have and we will continue to use WBS (Water Bacteria Solution)

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Documents

Location: Major Southwest Texas Universitycisnerosresearch.com/docs/SRB Presentation.pdf · 1 SRB Project – Sulfite Reducing Bacteria Primary Chilled Water Loop . Product: WBS (Water