;?§313€1‘?5?5L’?!?§i!:?’12<5'92""'" ' ' ‘ AN lfi‘w’ESTIGATiON OF THE mmcmou OF SYNTHETEC BR-iNE BY REVERSE OSMDSIS Thesis far the Degree of 3A. 8. .fiééGHEGAfl S‘s’fii’E BREVER‘SW KESARA BHUHTUMKQMOL 1973 ...... I! ‘ ~— ' BINDING BY 7 HOME & SONS’ 800K BWHERY INC. Lmnnra gmnrns ABSTRACT AN INVESTIGATION OF THE PURIFICATION OF SYNTHETIC BRINE BY REVERSE OSMOSIS BY Kesara Bhuntumkomol A study was made of the use of reverse osmosis to purify brackish water. The reverse osmosis system including the hollow fiber membrane cartridges was pro- vided by Dow Chemical Company. The feed brine used was of 8700 ppm concentration, closely resembling the Marshall formation, underground water in the Michigan area. Two hollow fiber membrane cartridges (Model No. J-267 and L6J2) were used, one at a time. The ion -2 +2 4 , Ca , Na+ and K+ were determined at different water recoveries over a period of time. rejections of SO water recovery and flux were also calculated. The accuracy of the result was tested by using a CA ratio. Analysis was done by injecting a radioisotope of the ion studied into the feed stream. Then the radioactivity was detected with liquid scintillation techniques. Kesara Bhuntumkomol The average total ion rejection was found to be 90% at steady state. The rejection decreased with increase of water recovery. Ions with larger charge and mass :2, Ca+2) were rejected more easily than smaller ions (80 (Na+, Ki). Water recovery of 30% is recommended for use with the brine to prevent chemical precipitation. Higher feed rates and system pressures should be tried using the Marshall formation. Further cost studies to determine the most feasible process for the brine should be done. AN INVESTIGATION OF THE PURIFICATION OF SYNTHETIC BRINE BY REVERSE OSMOSIS BY Kesara Bhuntumkomol A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Chemical Engineering 1973 To my parents ii AC KNOWLEDGMENTS The author wishes to express her gratitude to Dr. Bruce W. Wilkinson for his thoughtful advice and help during the study. Acknowledgment is due the United Nations Indus- trial Development Organization (UNIDO) for providing financial support for the Masters Program and to Dow Chemical Company for supplying the Dow Reverse Osmosis Unit. Help from Mr. Don Childs in fabricating and repairing the equipment and from Mr. Edward Brockbank in activating the radionuclide samples is also appre- ciated. iii ACKNOWLEDGMENTS . . LIST OF TABLES . . LIST OF FIGURES . . 1. INTRODUCTION. . 1.1 TABLE Recent Development 1.2 Purpose of Study. THEORY. . . . .1 Principles of Reverse Osmosis 2 Membrane. 2 2. Osmotic 2.2.1. 2.2.2. 2.2.3. 2.2.4. 2.3 2.4 2.4.1. 2.4.2. 2.4.2. 2.4.4. OF CONTENTS and Use Water Flux . Product Quality Concentration Polarization. System Pressure Loss. Plate and Frame Tubular Spiral WOund Hollow Fine Fiber. RAW MATERIALS AND EQUIPMENT 3.1 Raw Materials. 3.2 Experimental Equipment. EXPERIMENTAL METHODS iv 4.1 Preliminary Test. 4.2 Experimental Procedure. 4.3 Flushing of the System. 4.4 Safety Precautions . Membrane Transport Mechanism. RO System Parameters Page iii vii viii U1 \DU'I 12 12 15 18 19 20 21 23 24 24 25 32 32 33 36 36 5. ANALYTICAL METHODS . . . . . . . . . . . 5.1 Sample Preparation . . . . . . . . 5.2 Liquid Scintillation Spectrometer . . . . 6 0 DATA 0 O O O O O O O O O O O O O O 7. RES 7.1 7.2 8. DIS 8.1 8.2 9. CON 9.1 APPENDI Appendi A. ULTS. O O O O O C O O O O O O O 0 Cartridge Model No. J-267 . . . . . . . Cartridge Model No. L6J2 . . . . . . . 7.2.1. Decrease of Ion Rejection . . . . 7.2.2. Steady State Flow . . . . . . . CUSSIONS O O O O O O O O O O O O O Cartridge Model No. J-267 . . . . . . . Cartridge Model No. L6J2 . . . . . . . 8.2.1. % Ion Rejection. . . . . . . . 8.2.2. % Ion Rejection vs. Time. . . . . 8.2.3. % Ion Rejection vs. % Water Recovery 0 O O O C O O O 0 8.2.4. Permeate Flux . . . . . . . . 8 I 2 O S 0 CA Ratio 0 O O O O O O O O 0 8.2.6. Conductivity. . . . . . . . . 8. 2. 7. pH I O O O O O O O O O O O CLUSIONS AND RECOMMENDATIONS. . . . . . . Recommendations . . . . . . . . . . CES x Definition of Terms. . . . . . . . . . Analysis of Tap Water from Michigan State University . . . . . . . . . . . Analyses of the Marshall Formation Underground water 0 O O C O O O O O O I O O Neutron Activation and Radioactive Decay. . . Page 38 38 38 40 47 48 52 59 59 6O 60 61 61 61 64 66 68 68 69 70 72 73 75 76 77 APPENDICES Appendix Page E. Radioactivity Data . . . . . . . . . 79 F. Samples of Calculation. . . . . . . . 84 88 BIBLIOGRAPHY . . . . . . . . . . . . . vi LI ST OF TABLES Table Page 1. Chemical Makeup of Synthetic Brine . . . . . 24 2. Dow Hollow Fiber Module Specifications. . . . 30 3. Experimental Data Obtained for SO";2 Ion—- Cartridge Model J—267. . . . . . . . . 41 4. Experimental Data Obtained for so;2 Ion-- Cartridge Model L6J2 . . . . . . . . . 42 5. Experimental Data Obtained for Ca+2 Ion-- Cartridge Model L6J2 . . . . . . . . . 43 6. Experimental Data Obtained for Na+ Ion-- Cartridge Model L6J2 . . . . . . . . . 44 7. EXperimental Data Obtained for KI Ion-- Cartridge Model L6J2 . . . . . . . . . 45 8. Experimental Data Obtained for K+ Ion-- Cartridge Model L6J2 . . . . . . . . . 46 £2, Ca+2 Ions . . . . 49 9. Results Obtained for SO 10. Results Obtained for Na+, K+ Ions . . . . . 56 11. Summary of Results (Cartridge Model L6J2). . . 71 12. Analysis of Tap Water from Michigan State University . . . . . . . . . . . . 75 13. Analyses of the Marshall Formation Underground water 0 O O O O O O O O O O O O O 7 6 vii Figure 11. 12. 13. 14. 15. 16. LIST OF FIGURES Reverse Osmosis Principle . . . . . Plate and Frame Module Configuration (7) Tubular Module Configuration (7). . . Spiral WOund Module Configuration (7) . Hollow Fiber Module Configuration (8) . water Transfer in CA Membrane (21) . . Flow Diagram of Reverse Osmosis System. Front View of Dow Reverse Osmosis Unit. Rear View of Dow Reverse Osmosis Unit . % Ion Rejection vs. Time for so;2 Ion at 50% Water Recovery (Expt. 2) . . . % Ion Rejection vs. Time for so;2 Ion at 50% Water Recovery (Expt. 3) . . . % Ion Rejection vs. Time for $022 Ion (Expts. 6-7) 0 o o o o o o o % Ion Rejection vs. Time for SO"2 Ion at 50% water Recovery (Expt. 28?. . . % Ion Rejection vs. Time for Ca Ion (EXptSo 9-11) 0 o o o o o o o % Ion Rejection vs. Time for Na+ Ion (Expts. 12-14). . . . . . . . % Ion Rejection vs. Time for K Ion (Expts. 25-27) 0 o o o o o o 0 viii Page 11 11 13 14 17 26 27 28 50 51 53 54 55 57 58 Figure 17. 18. 19. 20. Dow Hollow Fiber Reverse Osmosis Cartridge % Ion Rejection vs. Time for SO“2 50% water Recovery (Expts. % Ion Rejection (at 120 min.) vs. Recovery Permeate Flux at 25°C (50% Water Recovery) VS. Time 6‘} Ion at % Water 28). Page 62 63 65 67 1 . INTRODUCTION 1.1 Recent Development and Use During the past 20 years, the reverse osmosis (RO) process has progressed rapidly as a promising method to recover water from saline solutions. Its advantages are simplicity and, theoretically, low energy require- ments-—no energy-wasting phase change takes place. All that is needed is a strong, corrosion resistant, reliable, cheap, selective membrane (1). The RO process is achieved by forcing a salt solution under high pressure past a semi-permeable mem- brane, which passes water more readily than other organic or inorganic materials. Interest in reverse osmosis first started in 1953 when C. E. Reid at the University of Florida found that secondary cellulose acetate (CA) may be used as a semipermeable membrane to separate water from saline solution by RC (2). However, CA had disappointingly low water tran3port and a very short productive life. During the 1950's, Loeb and Sourirajan at the University of California found that by heat treating the film and adding swelling agents to the casting formulation, they could make CA membranes which not only had excellent selectivity but also had water permeabilities sufficiently high to be of real practical interest (3). From that point on, the major advances have been the development, engineering and marketing of RO systems. Most of the research and development is sponsored by the Office of Saline Water, U.S. Department of Interior. Today, RO systems for water treatment are commercially available for any moderate need, ranging from a 2.5 gal./ day unit for a home drinking supply to a 150,000 gal./day auxiliary source for municipal water, a 350,000 gal./day plant for vacation resorts and 800,000 gal./day plants for industrial water (1). The sc0pe of RO systems is being extended to seawater desalting. Some other applications of R0 are: Food processing.--recovery of protein from cheese whey; concentration of maple sap, fruit juices, coffee and tea; concentration of drugs and biological products. Pollution control.-“removing chromate from cooling tower blowdowns; removal of sulfates from acid mine drainage; retrieval of gold, silver, platinum and other precious metals from electroplating solutions and rinses. Water reclaimation.--treating of secondary sewage effluent; reducing phosphate in the discharge (1). 1.2 Purpose of Study The purpose of the present study is to obtain data to determine the efficienty of the RO membrane by determining its ion rejection, flux,etc. (see Appendix A) using synthetic brine as feed solution. The composition of the synthetic brine used in this study closely resembles that from the Marshall for- mation, a brackish water source below the fresh water table in the central region of Michigan. The Marshall formation is found at a depth of about 600 feet (4). A U.S. Geological Survey of 1900 showed its salt concen- tration to be about 8768 ppm, including Ca+2, Na+, K+, 30-2, Cl-, HCO- ions (see Appendix C). It was once 4 3 hOped that this high concentration of salts could be separated and sold for profit. Now, thought is being given to this brackish source as potential municipal water. RO is looked upon as one of the best means to purify water from the Marshall formation. The equipment was provided by Dow Chemical Company. This RO study using a hollow fine fiber module consisted of 2 parts. First, the eXperiments were repeated using the cartridge Model J-267, which was used by Tucker in his M.S. Thesis (5). In the second part, the new cartridge Model L6J2 was used. The analysis was accomplished by using radioactive tracer technique and liquid scintillation. 2. THEORY 2.1 Principles of Reverse Osmosis Osmosis is the tendency of a solvent to flow through a semipermeable membrane from a dilute solution (water) to a concentrated one (saline) as depicted in Figure la. The driving potential for the flow of pure water is known as osmotic pressure (An). The actual flow of fluid is related to the chemical potential of the solution. This chemical potential is a function of the solution pressure, temperature and the number and types of molecules in the solution (6) or, Au V (AP - An) . . . . . . . (1) where: partial molar volume of water (pressure Osmotic Pressure Membrane Saline Water / Fresh Water 1c. Reverse Osmosis Figure 1. Reverse Osmosis Principle Using Raoult's law for dilute solutions, van't Hoff formulated an equation to calculate osmotic pressure: z) I! RT/V z nRT/v . . . . . . . (2) where: :1 ll osmotic pressure V = molar volume sr< T = temperature 5U ll proportionality factor When an external pressure equal to the osmotic pressure is applied to the concentrated salt solution, the flow of fluid will be in equilibrium as seen in Figure 1b. This condition is known as osmotic equilibrium. If the external pressure on the salt is continued beyond the osmotic pressure, a reversal of flow will take place. Pure water will be separated from the concentrated salt solution as shown in Figure 1c. This last phenomenon is the basis of the RO method of desalination. The following equations approximately describe the flow of water and salt through most current RO mem- branes (7). C4 ll L. I? KBAC KB(CW.- C ) . . . (4) P where: Jl = product water flux (gal./day - ftz) Kl = membrane permeability constant (gal./day - ft2 - psi) AP = pressure difference measured between the feed and the product stream (psi) Ar = osmotic pressure difference between the feed and the product stream (psi) Peff = effective membrane driving pressure (psi) (see equation 5) J = salt transfer flux (lb/hr.) K = proportionality constant (1'1 ll salt permeation constant 0 ll feed stream salinity measured at membrane wall C = product salinity Equation 1 indicates the significance of high fluid pressure on the water production rate. Acting in opposition to the pressurized fluid is the osmotic pressure of the saline solution. Osmotic pressure associated with typical brackish water feeds are in the range of 30 to 150 psi., where seawater may be as high as 450 to 600 psi. To assure a reasonable flow of product water through current high salt rejecting CA membranes, fluid system pressures in the range of 600 to 800 psi are required for brackish water feeds and up to 1500 psi for seawater feeds (7). 2.2 Osmotic Membrane The most important part of the RO system is the membrane. An ideal membrane is one which would allow only water molecules to pass through its structure (semi- permeable). A number of substances such as collodion, cellophanes, porous glass frits, finely cracked glass, inorganic precipitates and CA polymers have been used in fabricating semipermeable membrane films. A modified CA material has proven to be most satisfactory in demineralization studies. It has good selectivity, dope formulations amenable to variation, good availa- bility of raw materials and relatively low cost. There are 4 different basic membrane configur- ations currently being evaluated for use with R0 units (7). They are: 2.2.1. Plate and Frame The plate and frame configuration (see Figure 2) was the first type explored in early RO development and appears to be losing favor now. The advantages and disadvantages of the configuration are: 10 Advantages: (a) (b) (C) Design simplicity Physical ruggedness Only the membrane is replaced in the event of membrane failure. Disadvantages: (a) (b) Difficult brine flow patterns High labor requirements for membrane assembly and replacement High equipment cost Tubular The tubular configuration is similar to a typical shell and tube heat exchanger. Figure 3 shows a schematic of a typical design. This configuration has the follow- ing advantages and disadvantages: Advantages: (a) (b) (C) ((1) Well defined flow passages Filtration requirements are small Porous tubes can be utilized as both the porous structure and the membrane support. Ease of cleaning Disadvantages: (a) (b) (G) Large number of tubes and fittings required per unit surface area Low packing density Moderately high initial cost 11 Membrane Support Plates ‘1 ”,‘l’ ‘1 ‘ , /’/.v // l a [I’ll] ‘ Ill-IIII'I‘ i i I i . . 1111,11] | .‘l ‘ l \ \ N 7 I O, \T' Figure 2. Plate and Frame Module Configuration (7) Porous Support Product Water See Detail A Tube with Replaceable Osmotic Membrane 03 00 0°00 0° Brackish , 0:00 B , a I 0030 a Water , on ""9 00° 0 O . O Fiberglass Product Water Reinforced Epoxy Tube Cellulosic Liner Osmotic Membrane Tubular Module Detail A Assembly Figure 3. Tubular Module Configuration (7) 12 2.2.3. Spiral Wound Figure 4 depicts the configuration of a spiral wound membrane module. The advantages and disadvantages of the module are as follows: Advantages: (a) High membrane packing density possible (b) Adaptable to factory fabrication and simple field replacement of module Disadvantages: (a) Product flow path is long (b) A high level of feedwater filtration is required to prevent plugging of the brine side spacer (c) Module telescoping must be prevented 2.2.4. Hollow Fine Fiber The hollow fine fiber module which was used in this study was developed by the Dow, DuPont and Monsanto Companies. The configuration is similar to a shell and tube heat exchanger with a large number of hollow fibers (CA or nylon) serving as tubes. The fiber sizes are in the range 25 to 250p O.D. with wall thickness of 5 to 50p. The brine flows external to the fiber and the pro- duct flows through the fiber (see Figure 5). The advantages and disadvantages of this configuration are: 13 Brine-Side Separator Screen ‘ Brine Flow ‘ Product-Water Flow ' (after passage through Product Water membrane) Product-Water-Side Backing Material with Membrane on Each Side, Glued Around Edges and to Center Tube V Membrane Product-Water- Side Backing Material Membrane A 7 Brine-Side Spacer / Figure 4. Spiral wound Module Configuration (7) 14 Ammmm mamcwm I mmowuuumo mamcfimv Ame coaumusmflusoo mascoz Hmnflm 30HHom .m madman Ho>ou Hoccgu @ 33m cam @ Ezmssx $626: 263$ 000» 82.3.2933. 32.2 880 533333 none: 9318 636.3 @ to Ask} Xi‘an ammo ousmmcum @ E2m2§u629< 286$. not 0‘93... 23$»... xmttz 33<~GL2§ to 0.9.3: 323 s 52.5....» Sedan“? .2 {Omuo m2 92$ oleénwh 624.3. ms» 36% mummi 353K 02.90. 32$ «was: 33E / 1) x x E. x. . .z \ N \ V . . \\\x\ . 414.44.m.4 .114..4HH.11”144'4\.4 .w. . . . ... . ,.;...-... ... \.1.....~ 1.1.4.... kmdeo , , --4n|.I|H|4144 4...I. .. 4| II «has . 4.. ...|. .WMH . , l. . .HAHA .. A 58 . , 1.1““... in“... Burn". - 2\ § “z\n\a I . .uflu. . «flu. .u L _ 0N: ~2\NQ\W N\ 5 anflm .;:.,.; ....._.. ,. .:s. 4 . . a . . 144...... -- W W4 lax . I444|4.| IH.|4| 444I.|. 4 ill ./ P - 7_ % /A / \\ \ t .1 .n .1 \ .o\ \Sexfiunq ks aqskméitsu «use .333 was. ulti [nozkth usm 00 in» Romeo 15 Advantages: (a) High packing density '(b) Elimination of membrane support material require- ments (c) Little membrane compaction (with nylon fibers) (d) Large surface area/unit volume Disadvantages: (a) Factory fabrication and replacement of membrane module required '(b) High degree of feedwater filtration required (c) High efficiency desalting membrane has not been developed 2.3 Membrane Transport Mechanism A great number of papers have appeared in recent years suggesting transport mechanisms in R0 desalination. These suggestions include solution-diffusion models (9, 10), pore flow models (11), free volume models (12- 14), nonequilibrium thermodynamics (15-17), hydrogen ' bonding models (2, l8), capillary sorption models (19) and dielectric constant effect models (20). However, a physical theory which completely and accurately describes membrane performances to the satisfaction of all involved scientists has not yet been formulated. The most outstanding theory is the pore flow model, whose explanation of the transport of water and 16 salts across CA membrane is given in the following passages (l). Chemically, CA is a hydroxylic polymer made up of long chains of B-glucoside units (30,000-60,000) that have been acetylated with acetic anhydride and then hydrolyzed to reduce acetylation to about 40%. Most often, the CA powder supplied for RO membrane casting is in this partially acetylated form, which is known as 2.5 cellulose acetate. RO membranes are also cast from the fully acetylated form (triacetate). When cast as RO membranes, CA is a film about 4 mils thick. It is asymmetric--that is, the film has a thin, dense layer of about 0.25u above a thick, porous layer. Water passes easily from the dense layer through to the porous one, but with difficulty the other way. Unlike the thick, amorphous underlayer, the dense layer on top of the membrane is made up of tightly packed and organized chains of CA polymer that attract and hold water. Thus, water and solute are separated because the water molecules can form hydrogen bonds with the acetyl groups on the polymer, while many other Species cannot (see Figure 6). The CA polymer chains within the dense layer are highly organized because the membrane receives an annealing treatment that shrinks the film and crystallizes the polymer. The long molecules are somewhat separated 17 missus 0:03.09. 30983. .30. I ,4 1 . 1---! .55 0.55593 . l “ 1,4..1u W. _ / OAHU C.v 00 ON . V 4 _~ _” “m w. a H . /wi,v:» Q: mm \ w d. “.1 C CC CC CC. C\ m V. \./ \/ . t. . r, \ I. K .. \. / s W . C100C4OOCIOCCOO . _ . . P. w . . \ W... H! . H4. _ a... ./ C10 C1C-0CCO CCO w W . . r. 3.1. w. H 42 W. n c c r r U . . r. .L C10 C10 C10 C10 .. . . , , . , u , 7., I. X x \c \ft, \rw. > ”\pflarchClC_0{.C0ClC0.~ .V _ 1 4 o o 0 . I. _ w I. w W 3 _ WW I. m w w u “ . H _ H , H I. C1C C C C.C C‘C _ n _ . nw . . . o 0 o _ “orllllrn (@3295 :54ll1l t Water Transfer in CA Membrane (21) Figure 6. 18 and relatively immobile because of the interplay of van der Waals' forces. In this state, the polymer chains are close enough to crosslink with water molecules in the casting formulations and the annealing media. These water molecules bridge across adjacent chains by forming strong hydrogen bonds with the acetyl groups. In this way, the voids between chains are filled with bound-water molecules and no foreign substances can pass. If the polymer chains were not densely packed, water molecules would bond to acetyls on the same chain and leave voids through which foreign ions could pass. Water molecules move through the membrane by an applied pressure that pushes the water from a bond with one acetyl group to the next. Only a moderate force is necessary because the bonds are transferred, not broken. Dissolved ions or molecules that do not hydrogen bond cannot enter into attachments with bonding sites (acetyl groups) and are left to concentrate at the membrane surface. 2.4. R0 System Parameters There are 2 important parameters which characterize an R0 system: 19 2.4.1. Water Flux Product per unit area of membrane or water flux is defined as the amount of product recovered per day from a unit area of membrane. This flux is determined by physical characteristics of the membrane (e.g., thick- ness, chemical composition, porosity) and by the con- ditions of the system (e.g., temperature, differential pressure across the membrane, salt concentration of solution touching the membrane and velocity of the feed moving across the membrane). In practice, the properties of the membrane and the solutions are relatively con- stant, and water flux becomes a simple function of pressure, as described by equation 3. Flux declines with time for several reasons: -- Membrane fouling or temporary flux reduction is caused when foreign or nonhydrogen bonding materials (such as calcium carbonates, sulfate scales, hydrates of iron oxides and aluminum, silicates, miscellaneous particulates and biological growths) coat the membrane surface and interfere with inward movement of water. Most fouling can be minimized by pretreating the feed to remove iron and to control pH; by limiting the process to nonscaling concentrations of waste; by filtration and by injection of 20 small amounts of biocide. However, fouling always occurs no matter how thorough the pro- tection. The usual cleaning procedure is to flush the membrane with water and other cleansing agents. -- There is a compaction and compression that slowly reduces the water flux. This results from densification of the thin air-dried membrane layer and crushing of the porous structure of the membrane because of high pressure fluid. -- Another cause of flux decline is the hydrolysis of acetyl groups. The reaction results in a loss of hydrogen bonding sites, which reduces the water transport. This is why RO membranes are limited to a pH operating range of 3 to 7, out- side of which rapid hydrolysis and membrane degradation occur. The optimum pH range is 5-6. The reaction is also a source of salt leakage because there are fewer water bridges blocking the passage of foreign materials through the pore. 2.4.2. Product Quality Product quality is measured by the amount of solute or salt in the product. This depends on 21 selectivity of the membrane and its imperfections. The amount of salt passing through a unit area of membrane is described by equation 4. The amount of salt in the product depends on the physical characteristics of the membrane, such as thick- ness, salt diffusion and the distribution of solute between the membrane and the solution. From equation 4, normal salt flux is independent of pressure. The ability of the membrane to reject salts decreases with time. This is due to the following reasons: -- Hydrolysis of CA to cellulose as explained in 2.4.1 -- Membrane compaction which may increase the pore size of the membrane and thus reduce the rejection factor -- Coupling or membrane leakage because of imper- fections in the membrane through which the pressurized fluid can flow and contaminate the product water. Other pertinent parameters to be considered are: 2.4.3. Concentration Polarization Concentration polarization is a measure of the increase of feed water salinity at the membrane wall 22 beyond that of the bulk solution. The concentration polarization factor (CPF) is defined as the ratio of the salt concentration at the membrane wall relative to that in the bulk of solution. The usual CPF is 1.2 to 2.0 depending on design specifics (l). The adverse effects of this phenomenon are an increase in product water salinity, an increase in mem- brane scaling and an increase in osmotic pressure which means higher power requirements. In general, the magni- tude of the polarization effect is dependent upon the following parameters: (a) Brine channel configuration and dimensions (b) Brine flow velocity (c) Membrane water permeability To decrease the CP effects, the boundary layer at the membrane wall should be reduced by higher feed velocities and turbulence. However, there are 2 points which should be emphasized: I. High membrane water fluxes increase polarization effects. II. Increasing flow rates decreases polarization effects but increases the pumping power required. The Optimum flow rate should be designed for every application. At present, turbulence promotors 23 (e.g., small plastic balls, waffle-like polyethylene screens) are a more attractive way to reduce the boundary layer. 2.4.4. System Pressure Loss System pressure loss can be categorized as brine side pressure drOp (APB) and product water side pressure dro (AP ). p p The effective system driving pressure is defined by the following equation (7): P (P - P - APP) - An . . . . (5) eff L where: P = High pressure pump outlet pressure P = Pressure loss associated with the con- centrating feed water stream APp = Product side pressure drop An = Osmotic pressure gradient The brine side pressure loss is due to the friction pressure drop of the brine through the brine channel. Pressure losses are typically 50 to 150 psi or 5 to 15% of the total system pressure. ground water. 3. RAW MATERIALS AND EQUIPMENT 3.1 Raw Materials The synthetic brine used in the experiment shown in Appendices B and C. resembles that in the Marshall formation, Michigan under- The analysis of the top water and brine is For every batch of 50 gallons of synthetic brine the amounts of chemicals shown in Table l were mixed. Table 1 Chemical Makeup of Synthetic Brine Chemical Compound Amount (gm.) NahCO3, Commercial grade NaCl, Commercial grade MgCl2 - 6HZO, Purified grade KCl, Analytical grade NaZSO4, Purified grade CaCl Purified grade 2’ HCl (conc.), Analytical grade 681.0 565.0 85.6 22.3 124.0 202.2 650 ml. 24 25 Radionuclides used: 835 Ca45 Na24 K42 S35 and Ca45 were purchased outside the university. About 20 uCi was used in each experiment (2—2 l/2-hour operation). 24 42 . . Na and K were activated in the MSU Reactor Laboratory. Because of their short half-life, about 45 uCi had to be used in each experiment (see Appendices D and F). 3.2 Experimental Equipment The hollow fine fiber RO module used in this study was manufactured by Dow Chemical Company. The auxiliary system (model $03005 serial 1175) was designed and made by Polymetrics of San Carlos, California (22). Other supplement equipment was either fabricated by the MSU Division of Engineering Research Shop or purchased outside of the university. The process diagram is shown in Figure 7. The front and rear of the equipment are shown in Figures 8 and 9 respectively. Equipment used with the RO system included: 26 EmDmMm mflmoEmo mmno>om mo EmHmMHo 30am .b madman 3 d--- o “mum: mufl>auouccoo nmumsmuom wfiwwfihwm OHSUOZ om mmmsw musmmmum II QHvMHUCUUCOU Houofimuom mesa oudmmmum scam m>am> machoom \ moonm .mEmB mmmsw ounmmwum E llrllvxmll4 Hmuwz mm oumdz .lll AHV .............. deem swam a. a HHO>Hmmmm 4 mUHHUSGOAUmm one Uflod wmmsw JHMHll musmmwum ill/k mEdm mcfluouoz Hence: .caa meaxaz “madam 1m @mmm v--1~A u...- \«H -~ 1.1 .....‘. “\-1.4.. .p -.-I G D m --| 8 E 1n 0 (D m H 2 Q) n: 3 O Q 94 O 4434 H > 4.1 L1 0 H In Figure 8. - car-ti; 906/: IV - \r) - \./ uwco mamofimo mmud>mm 300 no 30.; “com .m 939nm 29 2 polyethylene tanks, each with a capacity of 55 gallons, for feed brine storage 1 motor pump with 1 HP 1 cartridge-type filter housing (5 u) l mixing tank with a capacity of 7 gallons 1 manual controlled chemical feed pump with a maximum capacity of 3.4 gpd. and a dial setting from 30-100 to indicate percentage of maximum feed rate 1 high pressure pump, Gould Multistage Centri- fugal 15 HP, 450 volts, 3 phase with a capacity of 2-6 9pm., maximum working pressure of 800 psi., and maximum working temperature of 160°F 2 Dow hollow fine fiber(CA) R0 modules with specifications as described in Table 2 (only one used at a time) The instruments included: 1 feed water pH monitor 1 feed water temperature guage 1 product water conductivity monitor pressure guages for the feed, system and con- centrate 30 .Q.O awn x .Q.H 1mm mum mama pumzpso >HHMHUmm .a.o now «an hmaa cumscH madmaomm msoscflpdou .Emm H mom 1 OH m.m I o.v Doom 1 0H mama com mmcwamsou uwa5muow> Eddflfidad ammum ov .zom Beau sxodm mace =Hu x .a.o .m.m Hmnwm mo mNHm mmpwupumu mamdwm mo mend m>wuo< mmcwuunmo mamcwm mo moo: 30am mucmumaoa oGMHOHnO mmdmm mum>oomm Hmong modem mm omdmm ousumnmmswa muammmum mdwumnmdo .xdz mucmoao can mum>oo Hoccmnu amwumumz Hamnm meHmcmEHQ Hamnm meq HOUOZ hmmlh HGwOE chHDMUAMHoon. mcowumowmwommm canto: Hogan BOHHom Boa m magma 31 -- product water flow meter -- concentrate brine flow meter The start-up of the system is accomplished with an automatic "on" button. The system can turn itself off when the inlet pressure drops below the minimum required for high pressure pump operation (about 10 psig.). 4. EXPERIMENTAL METHODS 4.1 Preliminary Test One of the.main problems which occurred at the beginning of the experiment was a difficulty in dissolv- ing all the chemicals to make up the synthetic brine. A test was done in laboratory scale to solve this problem. It was found that for every batch of 50 gallon brine, 650 ml. of concentrated HCl acid should be added to 30 gallons of tap water before the chemicals are added, beginning with NaHCO3, then NaCl, MgCl KCl, Na SO4 and 2’ 2 CaCl2 respectively. Stirring was done after each chemical was added. Tap water was then added to make up 50 gallons of synthetic brine. When this synthetic brine of pH about 5.6 was left at room conditions, the chemicals began to pre- cipitate after 80% of the water was evaporated. From the chemical report (23) of the synthetic brine, CaSO4 ° ZHZO will precipitate at water recovery of 83%. At this recovery, the solubility product of CaSO4 in the brine solution is 0.0016949. If the HCOS ions in the brine are reacted with H2804, CaSO4 . 2H20 will pre- cipitate at a water recovery of 39%. This is the 32 33 reason why HCl acid should be added in the brine instead of H2304 aCid. Another problem was the precipitation of hydrated iron oxide in the membrane module. This was due to the use of commercial grade CaCl (92% CaClz) which contains 2 some iron oxide. It has been found that iron hydroxide is one of the major constituent of fouling layers formed during brackish water disalination (24). In the present study, purified grade CaCl was used instead. This 2 resulted in less iron oxide precipitation. 4.2 Experimental Procedure Synthetic brine was prepared as described in section 4.1. in the polyethylene tanks. It was desirable to have the room fully ventillated so that acid fumes could be dispersed quickly. Prior to experimentation, calibration of the pH meter was necessary (22). The pH probe had to be checked to see that there was enough saturated KCl solution. The procedure for start-up and experimentation was as follows: Steps 1. The brine or concentrate valve was opened fully. 10. 34 A check was made that an adequate supply of radionuclide solution was available, and that the pumplines were primed and leak free. Tap water was allowed to flush the system to remove air. This is completed when no bubbles appear in the brine rotameter. The brine flow was adjusted to about 2 gpm. The high pressure pump was then turned on with the "auto" button. Re-adjustment was made of the concentrate flow for the desired rate. When the flow was steady (about 15-20 minutes), flow rates of both concentrate and permeate were measured by weighing the amount of water at definite times. This was done at least twice and an average value was taken. Samples of feed, permeate and concentrate were taken to measure the background radioactivity level. The radionuclide was then introduced into the system by turning on the chemical feed pump. After the radionuclide had been introduced into the system for 15 minutes, the feed valve was switched from the tap water to the prepared 35 synthetic brine. The time was noted as the starting time (t = O). 11. Samples of feed, permeate and concentrate were taken in small polyvials. Subsequent samples were taken at 60-minute intervals for 2-2 1/2 hours. 12. Periodic checks of the pressures, pH, temperature and conductivity were made during the experiment. 13. When all samples had been taken, the injection of nuclide was stopped. 14. The system was then flushed with tap water for at least 2 hours, usually at higher flow rates than were used during the run. 15. All power to system was turned off. There were only two polyethylene feed tanks used in the experiment, so the feed valve had to be switched from one to the other after the brine was almost gone in the first tank. The brine had to be prepared and used at once. It was very easy to lose the priming on the radionuclide feed pump. The best way to avoid this was to keep the suction end in solution at all times when not in use, to take it out of solution between pulses and to shake the bubbles out of the suction tube after placing it back into the solution. 36 4.3 Flushing of the The system had to be flushed experiment to remove the radioactive cipitates from the brine. Tap water System at the end of each ions and the pre- at 50 psig. with a flow rate 2-3 times that of the brine flow was usually used. From time to time, the system was flushed with radiacwash solution (chelating agent) using recycle flow for 2-3 hours. The radiacwash (1/2 gallon radi- acwash in 50 gallon tap water) helps to solubilize radioactive ions and also other chemical ions. 4.4 Safety Precautions The following precautions were followed during the experiment at all times: -- A pocket film badge was worn when using radio- nuclides. -- Plastic gloves were used when preparing the radioactive samples and taking samples during the experiment. -- To reduce contamination from leakages or spills on the equipment and floor, absorbent paper was taped to parts of the RO unit as well as to the floor near the outlet streams. 37 Contamination wipes were taken after each experi- ment to determine if the equipment was becoming too active for safety. All sample polyvials and glasswares were thoroughly cleaned with radiacwash solution and hot water after each experiment. All contaminated liquids were disposed of in the prOper radioactive container. The RO system was flushed with tap water for at least 2 hours after each experiment to reduce the amount of radioactivity in the system. 5. ANALYTICAL METHODS The radioactivity in the samples was analyzed by using liquid scintillation spectrometry. The system used was a Packard Tri-Carb Liquid Scintillation Spec- trometer System, Model 3003. 5.1 Sample Preparation Ten millilitres of radioactive aqueous sample was mixed and shaken vigorously with 10 ml. of Packard Insta Gel Emulsifier in a polyethylene vial. If the solution was not clear, the vial with the solution was placed in ice water until it was clear. For background counting, the aqueous solution sample collected before the injection of radionuclide was mixed with the Insta Gel. 5.2 Liquid Scintillation Spectrometer Procedure: 1. The temperature in the counting chamber was adjusted to about 5°C. 38 39 2. The gain was set at maximum. This gain had been determined before for each nuclide (25). 3. The sample vial was then placed to count for 50 minutes or 100,000 counts depending on which was reached first. The sample no., time and counts in all three channels were printed out by a digital printer on paper tape. This particular spectrometer has a sample changer with a capacity of 200 sample vials. Each successive sample is automatically counted one after another (25). 6 . DATA The experimental data using cartridge model J-267 are shown in Table 3 and cartridge model L6J2 in Tables 4-8. The feed, system and concentrate pressures (see Appendix A) were kept within ranges of 12-16, 665-670 and 650-660 psig. re5pectively. The temperature of the feed brine was around 59-67°F, except in the first two experiments where hot tap water was used to dissolve the chemicals instead of cold water. The feed was adjusted within a pH range of 5.6-6.1 to avoid membrane deterior- ation and chemical precipitation. The radioactivities of feed, permeate and con- centrate streams (see Appendix A) were measured at par- ticular times to determine the ion rejection of the mem- brane. Raw data are presented in Appendix E. At the same time, the conductivity of the permeate stream was also taken. Stream flow rates were measured to determine the water recovery and permeate flux (see Appendix A). Appendix F includes methods of calculating permeate flux at operating temperature and at 25°C, and water recovery. 40 4].- . oa an nowadwuass I xm m me.o me.o MN~.o x-.o xvu.o h.m m mo.v xe.m um.n xa.v mm.~ o.o m so.a ma.a axm.H 44 44 m.m H omH ONH om on on 1.caso mafia name .02 a . a loomm an .soxoasouoaeo m u xm Eoonuw ouoosuom cw hufi>auosodoo coon mo noun: mas o.om NMH.H mn.o ms.o oo4am can one as 44 m 44 m.~m enm.o mm.o mn.o ~m4mm owe one ma 44 ~ 44 s.mh ~os.c nm.o H~.o va4ns coo one ma4na 44 a Awe Amuo\eaoc 1.5dmc x.sdmc is . ..uammc ..mammo ..maaao 1.cwan.uac .oz ouoz huo>ooom UomN no Mdah ouom Beam ouom .mfima .moum .noum .moum ofiwa . mkm Houoz ouoofiuom ouoofiuom 30Hm .ocoo .OGOU Eoumwm doom unannoum u no~4u Hoeoz omeauuuao44coH «wow you eoaaauno mung Huucosauomxm m oanofi . oH an cowaaauaaa 4 an 442 m xm.~ Mo.~ 44 x~.~ 44 xv.~ so.~ 44 44 o.o SN 11 11 11 mom.o mum.o mmH.H mmm.o 11 11 m.m ma 11 11 11 mwv.o Mma.o M~.o mmh.o n.m m.v o.m m 11 11 11 m~.o an.o mmo.o oma o.m h.v h.m h 11 11 11 Mon.o Noa Mm~.o Mmh.o m.m n.v h.m m 11 11 11 moa va.o on mm H.h m.m m.m m 11 11 mm.o mm mm mm~.o omv.o 11 11 h.m v ovm oma oma oNa ca cm on A.GHEV osva .oaoo ovmosuom pooh .oz loomm an .onoaeouoasc ma .uaxm Edouvm ovoofiuom cw avfl>fivoaccoo m.om «mm.o No.0 Hw.o mo1mm mmm one ma omumm mm ~.om hmv.o mv.o nv.o «m1ow mmw ohm ma moumm ma m.m~ Hum.o_ . vm.o «m.H omImm omm chm NH omnaa m m.~o th.o oo.o mm.o ~u1mm own one ma once u m.om mvm.o mm.o hm.o mm1oo mmm mom «a omum m m.mv Nmm.o mm.o ~m.o Ho1¢m mmm one «H omnm m >.m¢ 5mm.o hm.o mo.o ow1mm mmw chm ma o v E .5339 1.53 1&3 1 a 3 1.3.3 1.3.3 1.3.3 1.5.: .5: .oz auo>ooom comm va xsam ovum 30am ovum .msm .noum .moum .moum osva . ex uovoz ovooeuom ovwofiuom . 30am .ocoo a .ocou Eovuhm coom mcwvuovm v m Nwow non cocaauao sumo HancoEHHomxm v oanoa News deco: omeauuuau44aou 443 . as an emaamauase 4 ma m mom.o eva.o .sma.o so.H 44 44 m.m 5H smo.o mmo.o xmo.o xmm.o n.m v.4 o.m Ha xva.o Mam.o wa.o xm~.a ~.o «.4 m.m oa xHH.o xma.o mam.o exam.o o.w m.v s.m a oma cm on on A.GHEV oEHB .ocou ovoofiuom pooh .oz loom” um .so\oasouoae. .udxm mm Eoouvm ovooahom cw mvw>wvosucou c.om mvm.o mm.o mm.o vw4~m mmw ass «a mmnom AH m.m~ ouv.o me.o mH.H mo4om omm mam NH omuna Ha o.mo ~mm.o mm.o mm.o no owe ohm «a4ma omuma OH o.Hm mmm.o mm.o mm.o ~u4ow com one uH4nH owuna a lac, Amumxeamc 1.8mmo 1.2amc .m . 1.mamac ..mamac 1.aamac .1.aaeu.uno .oz muobooom Uomm vo xdam ovum 30am ovom .mfim .moum .ooum .moum oEHB . m uova ovoofiuom ovooEuom 30am .ocou a .0:00 sovmhm pooh mcwvuovw v xm whoa Homo: omcfluvuoollcoH +ou MOM vodwovno cvmo HovcoEHuomxm N m oHnoB . OH an amaflmauase 1 ma 44 m mma.o Mam.o mem.o xv~.a 11 11 m.m ma Mmm.o Ma.o moa.o mN.o 11 11 >.m «a mmm.o .mha.o mmm.o mHH.o 11 11 m.m ma m~.o ummm.o hm aha mo.m m.v m.m NH oma om on on A.cwEV oEHB .ocoo ovuofiuom pooh .02 .vme Aoomm vu .EO\oonuowev mm Euouvm ovuofiuom cw hvw>wv05ccoo v.om mvm.o. mm.o hm.o moIaw mmw chm mHIvH .omumm ma m.om mmv.o vv.o mm.o omlmm own cum walvd moqu va m.oo cam.o mm.o wm.o voInm mmm chm mHIVH mouuw ma m.om Hmm.o om.o mm.o moIam mmw chm VA . omuma NH 1.1 imuuxoaoc 1.2amo 1.2amc .m c 1.mamac 1.mama. 1.mamac ..caa..uec .oz muo>ouom Oomm vu xsam ovum 30am ovum .dsm .noum .noum .moum oEHB . m uovuz ovuoEuom ovuofiuom 30am .ocoo a .0:00 Eovmam pooh mcwvuuvm v xm Noon Homo: omovuvuuo11coH +uz mom cocauvno uvuo Huvcoavuomxm w manna . oH an amaaaauaas 4 x m n .vcoEHuomxo onv oHOMon .H: H MOM Smuzouwouu svws mcwnmsamu mNH.o Ma.o Mmo.o Mao.o m.m NN 445 xmv.a xvo.a xva.o xv.a m.m Hm mma.o smo.a so~.o xmm.o e.m om sm.a xmm.o xm~.o xvo.H m.m ma Mm~.o xvm.o mmm.H nxvm.o h.m ma oma om om on a.:«EV oEwB pooh .02 mm .vdxm Aoomm vu .EU\OAEOHOMEV suouvw ovuoEuom aw >vw>wvospcoo N.om mmv.o Nm.o Hm.a mmlnw 0mm onw VHIMH omuov uNN m.Hw mmm.o «v.0 av.o mwlmw mmm chm va omnmm Hm m.om vhv.o om.o VH.H Holow omm mow ea omuwm om N.Hm th.o Hm.o mm.o volmw mmm Ono «H . omuvm ma m.om vvm.o mm.o hm.o mwle mmm mmm VA omumm ma Awe Amvu\udoo 1.8dmo ..sdmc .m o ..mammo x.mvmdo ..mvmmc ..caeu.unc .oz huo>ooom uomm vu xSHm ovum 30am ovum .mEm .monm .moum .moum mafia .vmxm uovuz ovuofiuom ovuofiuom 3on .ocoo a .ocoo Eovmam boom msflvuuvm Noon Homo: omowuvuuUIIcoH +m How vocauvno uvun HuvcoEHuomxm h oHQuB moH an cowamvvass u so .vaofiquomxo onv ouomon mcflcuoao mend coflvuonsw oUHHoscowoumn .ocfla coon ca asexuoqu «46 so.~ x~.m mm.~ Mo.m m.m hm xv.~ x¢.~ xm.~ us.~ m.m mm x~.~ x~.~ xm.a Me.m H.u mm xH.m x>.~ xH.~ so.m o.m an sma.o xm~.o xm~.o oxm~.o m.m MN oma om om om A.cwev oEHB boom .oz mm .udxm Auomm vu .EU\0£Eou0fiEv Euouvm ovuoEuom cw mvw>wvodocoo o.oo Hem.o vm.o mv.o mmlmm coo chm oHImH omnom hm o.om Nmm.o ~m.o No.0 hm1mo mmo 05¢ «a omumw ow w.mm oam.o mm.o Hm.a mwlmm omw moo MHINH . omumv 9mm «.mm mom.o No.o mv.o mw1vo mmw chm malea . omuvv uvw o.om mhm.o vo.o mv.o solmm mmw chm ma omumv mm E 5333 1.33 1&3 a c 1.343 1.333 1.343 1.3.: .5: .oz muo>ooom comm vu xdam ovum 30am ovum .mmo .moum .moum .moum oEHH . mx uovuz ovuofiuom ovuofiuom 30am .ocou a .ocoo Eovnhm Boom mcwvvuvw v m meA Home: omUHuvHuUIIQOH +m How convuvoo uvua HuvcoEHuomxm m oHQuB 7 . RESULTS Four different ions were measured to find the efficiency of the hollow fine fiber RO module: Ca+2, Na+, KI and 80:2. The raw radioactivity data in Appendix B were used to calculate the percentage of salt rejection of the RO module, by using the equation: (Feed Activity - Permeate Activity) FeediActivity % Ion Rejection = 100 x To determine whether the result was accurate, a parameter called the CA Ratio was designed. This ratio was defined as the ratio of projected concentrate activity rate to actual concentrate activity rate (see Appendices A and F). Ideally, this ratio should equal 1.0. A value less than 1.0 indicates that more radioactivity is leav- ing the system than entering (theoretically impossible). This may be due to improper mixing in the R0 system or error in scintillation counting or to dissolution of precipitate within the apparatus. A CA Ratio greater than 1.0 indicates that some of the nuclide is depositing in the system or there are errors in scintillation counting. 47 48 Appendix F includes methods of calculating ion rejection, water recovery and standard deviation. 7.1 Cartridge Model No. J-267 This cartridge was used by Tucker in his M.S. Thesis (5). It was plugged with precipitates which caused scattered results and low ion rejection. In the present study, the experiments were rejected using the same cartridge to determine % ion rejection of so;2 in the synthetic brine. The result is shown in Experiment 1 in Table 9. To remove the precipitates, the system was flushed with radiacwash for 3 hours. Then the experiment was repeated. The result using synthetic brine as feed is shown in Experiment 2 in Table 9 and Figure 10. Another experi- ment using tap water as feed is shown in Experiment 3 in Table 9 and Figure 11. Improvement in % ion rejection is shown in Experi- ments 2 and 3. This might be caused by flux increasing which helps to reduce the concentration polarization or by flushing. The improvement of CA ratio (see Table 9) indi- cates that some precipitates were removed by flushing. However, % ion rejection of so;2 in both experiments is still low (69-71%). The ion rejection in Experiment 3 is lower than that in Experiment 2. This may be due to the precipitation of chemicals during Experiment 2. 49 44 ma.a mo.a HH.H nv.o 1444 m.“ a ~.oa m.~ a o.pm m.H « m.mm «.4 a o.vm o.om mmuom pH 44 mo.H mo.H mm.o ma.o 4444 H.~ a m.mm ~.~ « m.mm «.N a s.mm m.~ a m.~m m.a~ omuna AH 44 ~H.H ~H.H mH.H n~.a 4444 m.H a ”.mm m.a « o.mm o.a « o.mm F.H a o.om o.mo omuma SH 44 mo.a «H.H so.a o~.~ 4444 o.« « o.vm S.” « v.um n.H a o.Hm m.H a H.4m o.am omuna m ~+ao 1.:ae ov~o 1.eas omac 1.:ae onac mo.H mo.H mo.a ~H.H v~.a v.H a m.ma n.H a m.mm ~.H a m.am n.a a M.SS m.” a o.wm m.om omn~m mm 44 H~.H mo.H «H.H mm.a 4444 o.a a «.ma u.a a m.nm b.H a m.om m.a 4 «.5a ~.om moumm ms 44 no.H mH.H mo.H m~.H 4444 m.~ « ooa m.~ « ooa s.~ « cod m.~ a ooa m.m~ canaa m 44 H~.H aw.” ea.” mo.m 4444 ~.H « ~.sa ~.a a o.mm ~.H « a.mm v.a a m.oa m.~o on.» s 44 Hm.o mo.o ma.” ~m.a 4444 m.a « o.mm a.a “ H.~a s.a « «.mm p.H « a.ma m.om om.m m 44 ~H.H ha.a ma.a om.a 4444 ~.H a n.om H.H « s.om «.H « ~.pm n.H a H.mm m.mv omum m ma.a ma.~ a~.~ 44 44 m.a a ooa m.a « «.mm o.~ u m.oa m.~ « o.mm H.m « «.vm “.mv o a ~wom Ho.a mo.” vo.a wo.a nm.a ~.~ a o.mm «.~ 4 h.mo n.~ a o.po ~.~ « o.a~ H.~ a ”.mn o.om 44 n mm.o oo.a sm.o oo.H 5H.a o.a « «.«h o.a a m.as m.a « n.ah o.a « 5.Hs Q.“ « n.on m.~m 44 N mm.a ~o.a an.” 44 44 s.~ a o.oa o.m » o.o~ o.v a H.v~ 44 44 h.me 44 H Nmom and oNH on on on one owe as cm on lac 1.:Heu.unc .oz 1.cwec wave 1.:ve. wave suo>ooom mafia . a com Hove: mcavuuvm v am cavam «o noavoonom can a neon ~+ao . ow uou convauno «vacuum a oHnuB 50 AN .vmxmv muo>ooom uovuz wom vu coH Nvom How oEHB .m> coavoohom coH w .oa ousmflm Acflav oEHB oma oma om om om a 1 a _ 1 a a AGOHqu>oQ ouuocuvmv ca 1 ow om om on om om 00H UOInoateH % 51 Am .vdxmv muo>ooom uovuz mom vu cOH omH ONH Aaoflvufl>oo puupcuvmv DH A.CHEL oEHE om . wow MOM oEHB .m> coflvoohom coH w as .JOOH .HH ousmflm uotqoefeu % 52 After Experiment 3, it was decided that the cartridge model J-267 is inefficient and should be replaced by a new one. 7.2 Cartridge Model No. L6J2 The ion rejection of 4 different ions (SOZZ, +2, Na+, KI) were determined, each at 3 different Ca water recoveries (30, 50 and 60%). Synthetic brine was used as feed in every experiment. The results of 5022 ion rejection are shown in Experiments 4-8, 15 and 28 in Table 9 and Figure 12. The ion rejection results are quite high, esPecially at water recovery of 30%. This is due to the new cartridge used. There was no effect due to pre- cipitation and membrane compaction yet. The results of Ca+2 ion rejection are shown in Experiments 9-11 and 17 in Table 9 and Figure 14. The results of Na+ ion rejection are shown in Experiments 12-14 and 16 in Table 10 and Figure 15. The results of K+ ion rejection are shown in Experiments 18-27 in Table 10 and Figure 16. Experi- ments 19-21 showed a fluctuation of results. This was caused by precipitation of ions. The system was then flushed with radiacwash for 1 hour. Experiment 22 gave better results but during Experiment 23, there was a leakage in the feed line. The system had to be opened 53 Able .mvmxmv cOH meow How oEHB .m> coHvoonom coH w .NH onsmflm ads 459 oma omH om om om _ a _ _ a a 1 m a L Acoflvufl>oo onupcuvmv ow muo>ooom novuz woo huo>ooom Hovuz mom on om om ooa Hornoafiea % Amm .vdxmv muo>ooom Hoqu mom vu coH vow How oEHB .m> COHvooflom GOH m .ma oudmflm 54 Nl 1.55 2E. com com oma ONH oo o e m 1 _ A m m _ _ a on AGOHqu>oQ UHuUCuvmv 0H 1 W l l om % H a rL. W l e W a 1 T..- O u l OOH 55 Aaalm .mvmxmv :oH AGOAvufl>oo Unupcuvmv on 4 >Ho>ooom Hovuz wow 1 muo>ooom Hovuz won 4 muo>ooom uovuz mom 1 N +uO How oEHB .m> COAvUonom coH w 1.2.53 45.9 cm om 4% 1v a. _ .va onomflm on om uornoeCeu % om ooa 565 m~.H Hm.H «~.H mm.H 4.H H h.mn o.H H name o.H H m.~s o.H H H.~H o.oo omuom pH oo.H Ho.d ~H.H HH.H o.H H «.ms m.o H H.sp m.o H «.0» m.o H m.vs o.om onus. mm mo.H mo.H mo.H mo.H o.H H o.~m o.H H v.~m o.H H n.Hm o.H H m.mh «.mm omuov mu 44 as.q ~m.a oo.H 44 m.H H m.vm H.H H a.am q.H H «.mm ~.mm omuvq an 44 ~4.H ao.a mH.H 44 o.H H H.mm H.H H m.mm H.H H o.mh a.am omuuv MN mo.a mo.o mm.o Ho.a v.a H ~.mm m.H H m.as m.” H o.mm n.H H H.mm ~.om omuov Hm Hm.” m~.o ~m.o am.H m.o H m.om m.N_H ~.om v.H H H.ms m.o.H v.ua m.Hm om.an an ov.H em.o no.0 ow.a ~.H H n.vm H." H a.eo m.~ H s.mn m.H H m.us m.om omnmn om mv.o a~.H oo.o as.” o.~ H «.mo m.~ H m.~m H.H H m.~o a.o H o.om H.Hw omuvm as ~m.o Ho.H HH.H mH.H o.H H ~.Hm o.H H o.am a.o H a.om m.o H m.Hm m.om omu~m ma +x oo.H Ho.H oo.H. OH.H v.~ H m.om m.~ H m.om ~.~ H o.mn H.~ H o.~a v.om o~nm~ ma mo.H No.H oo.H mo.H ~.H H H.5m ~.H H o.~m ~.H H m.ua H.H H n.sa w.om noan «a SH.H mH.H am.H m~.a m.o H «.mm m.c H m.vm 5.0 H n.ma m.o H ..~m m.om mo.- na mo.H H~.H sm.o mH.H «.4 H m.mm o.q H o.Hw ~.v H ~.as o.v H H.~m n.om omnma «H +az oNH as on on ONH as as on 755 were 755 05a. a 3; Guanine .oz H0>OOON 05H? COH oHuam no eoHuuoHou can a Haves .maauuaum .umxm mcoH +m .+uz How oodHuvao vasnom OH Oanua 57 AvH4NH .mvmxmv GOH +uz How oEHB .m> COHvoonom coH w .mH oHsmHm A.GHEV oEHB oma OS om om om _ _ 1 A H _ a H _ a mno>ouom Hovuz wow 1 mno>ooom Hovuz wom 4.< muo>ooom Hovuz wom 1 AGOHqu>oQ puucduvmv 6H 4 W on om om ooa uorqoefeu % 58 Anm4mm .mvdxmv coH +m How oEHB .m> cOHvooflom coH w 335 as: omH QNH om _ fl _ H _ W >Ho>ooom Hovuz wow 4 >Ho>ooom Hovuz mom 1 < muo>ooom Hovuz won 1 o AcoHqu>oo puupcuvmv 6H 1 .SH magmas on I.OOH UOTQSBCGH % 59 for repairs. There was a disorder in the suction end of the radionuclide injection pump during Experiment 24. The pump lines had to be cleaned. The results were improved in later experiments (Experiments 25-27). 7.2.1. Decrease of Ion Rejection EXperiments 15-17, 25 were also performed to determine the decrease of ion rejection after a longer period of time. This decrease in ion rejection can also be noticed from the conductivity data in Tables 3-8. The conductivity of the product stream was increased with no. of experiment or time especially from Experi- ments 23 to 24. 7.2.2. Steady State Flow Most experiments showed consistent CA Ratio, except for the first 30 minutes. This was caused by the unsteady flow and mixing at the beginning. From the results, it is noticed that the steady state was approached in about 30 to 60 minutes. 8. DISCUSSIONS 8.1 Cartridge Model No. J-267 Experiment 1, which was repeated using the same condition as Tucker's Experiment 39 (5), showed the same scattering and low so;2 rejection. This was due to the precipitation of ions in the membrane. For synthetic brine with 8700 ppm. concentration, CaSO4 will precipi- tate if the water recovery is more than 83% (23). How- ever, even when less than 83% recovery is used, precipi- tation can occur in the R0 system because of the polari- zation effect as stated in 2.4.3. In Tucker's experiment, the water recovery used (70-85%) was too high. This high water recovery or low feed rate increased the concen- tration polarization effect. The ion concentration near the wall became more than the concentration in 83% water recovery, so the ions precipitated in or on the membrane. Other causes might be the deterioration of the cellulose acetate with time or sWelling of the membrane because of the high pressure used as discussed in 2.4. Experiments 2 and 3 showed the result after the cartridge was flushed with radiacwash solution for 3 hours. The % ion rejection was improved with more 60 61 consistent results. However, the % rejection of 70.0 is still too low to be practical. The cartridge was con- sidered inefficient and was not used further. When the cartridge was removed from the system, a lot of precipitates including iron oxide were found both in the solution and on the membrane wall (see Cart- ridge Model J-267 in Figure 17). The iron oxide came from the unpurified CaCl2 used. 8.2 Cartridge Model No. L-6J2 8.2.1. % Ion Rejection Of all the ions, $042 was shown to be the ion most rejected by the RO membrane as expected. The reasons are that the so;2 ion has the largest charge and mass. The ion rejection usually increases with the change on the ion and its physical size (1). The next most rejected ion was Ca+2. The next one should be K+ because of its larger molecular size than Na+. In this experiment, it was difficult to distinguish which one is more rejected, because of the precipitation of chemical ions and the resultant lowering of the ion rejection with time. 8.2.2. % Ion Rejection vs. Time Figure 18 shows that the % ion rejection of so;2 ion decreased with time. The time plotted is not Figure 17. Dow Hollow Fiber Reverse Osmosis Cartridge 63 Amm .mH .m .mvmxmv muo>ooom Hovuz wom vu coH Nwom HOH oEHB .m> COHvoomom coH w .ma oHsmHm 1.Hac msHH pm om ow om o 1 A a _ A, a. a om AcoHqu>oQ UHuccuvmv 6H 1 uotaoefau % ooa 64 continuous. It was accumulated from successive experi- mental times when synthetic brine was used as feed, not including flushing time at the beginning and end of each .experiment. It is noticed that the iron rejection drOpped quite distinctly at a time close to 50 hours. At that time, the system was opened to repair leakage in the feed line. The membrane could have dried. This caused the deterioration of the CA membrane and thus decreased the rejection ability. 8.2.3. % Ion Rejection vs. % Water Recovery The results of ion rejection vs. water recovery of 4 different ions are shown in Figure 19. From the results, the lower the water recovery, the higher is the ion rejection. This is due to the higher feed rate or turbulence when lower water recovery is used (the permeate rate remained almost constant for all eXperi- ments). This higher turbulence helped to reduce the concentration polarization effect and thus reduce the ion concentration near the wall. As discussed in 2.1, the salt flux depends on the feed concentration near the wall (Cw) as follows: J2 = KB (Cw - Cp) 65 mno>ooom Hovuz w .m> A.cHE oma vuv cOHvoomom coH w >Ho>ooom Hoqu w om om ow H _ _ HI _ _ AGOHqu>oo Unuocuvwv 6H.4 W Om I .ma musmflm om om om on om om ooa uorqoefea % 66 For 8022, there is just a little decrease in ion rejection when water recovery is increased from 30 to 60%, about 3%. Water recovery plays an important role in Ca++ rejection, accounting for about 10% change when water recovery is varied from 30 to 60%. In this case, the +2 Ca ions can be precipitated as CaCO3 or CaSO4. CaSO4 precipitates when its solubility product in the solution reaches 0.0016949 (23). At high water recovery, Ca++ may precipitate and thus the ion rejection is lower than usual. For Na+, the ion rejection decreased about 4% when water recovery was increased from 30 to 60%, whereas 0 I O + about an 8% ion rejection decrease was observed for K at the same water recovery increase. 8.2.4. Permeate Flux Figure 20 shows that the permeate flux remains almost constant with time (accumulated time from suc- cessive experiment), except at one point. This may be due to the error in measuring the flow rates at that point. The permeate flux of the membrane model L6J2 is quite low because of the large active area of the membrane (1895 ftz) and the low feed rate used. To increase the permeate flux, the low pressure applied 67 ow oEHB .m> Amuo>ooom Hovuz womv Oomm vu xdam ovuoEHom om 1.unc meHa ow 0H _ .om ovsmHm m.o v.0 m.o w.o m.o (zqg/pdfi) xntg eqeemxed 68 to pump the feed stream in should be increased. How- ever, larger feed storage tanks should be used too. The increase in feed flow rate will help to reduce the concentration polarization effect, and improve the A product quality. 8.2.5. CA Ratio Most of the CA ratio at 30 and 50% water recovery are close to 1.0 (see Tables 9 and 10). This shows that there was no precipitation occurring during the experiments. At 60% recovery, CA ratios are much more than 1.0; however, they are consistent. The high CA ratio shows that the ions might be precipitating in the membrane. At this point, it can be concluded that there was precipitation occurring at 60% water recovery using synthetic brine as feed. 8.2.6. Conductivity In some experiments, the conductivity was not constant as it should be. This may be due to insuf- ficient mixing of feed solution, or precipitation in the membrane. The increase of conductivity of the permeate stream with no. of experiments indicates that there was precipitation occurring during the experiments. The 69 conductivity increased sharply in Experiment 24. This may be due to the dryness of the membrane as stated in 8.2.2. 8.2.7. pH The pH of the feed brine was controlled between 5.5-6.0 to avoid deterioration of the membrane. The average pH is about 4.7 for the product stream and 6.0 for the concentrate stream. The lower pH in the product stream is due to the lower salt and higher CO2 concen- tration. A lot of CO2 was produced when HCl acid reacted with NaHCO in the feed brine. Most CO2 can 3 permeate through the membrane (26) and thus lower the pH of the product stream. The pH of the product water increased after letting the product water stand so the CO could escape. 2 9. CONCLUSIONS AND RECOMMENDATIONS Using synthetic brine as feed in Dow R0 systems, ion rejections of the hollow fine fiber membrane were studied for SOZZ, Ca+2, Na+, K+ ions. Ions with larger charge and mass, such as 8032, are more rejected by the membrane. Ion rejection is also quite high at low water recovery because of the high turbulence near the mem- brane walls. The results also show that there are chemicals precipitated at 60% water recovery. Using 50-60% water recovery, the system has to be flushed with radiacwash solution or other cleansing agents every 20-hour operation. To avoid the chemical precipitation, low water recovery at 30% should be used. The system can then be flushed after longer periods of Operation. The average total ion rejection of the membrane is about 90% at 50% water recovery and system pressure of 670 psi. If higher system pressure (> 700 psi.) is applied at lower water recovery (30%), the ion rejection may be increased to 96%. The product water can then be used as potable water. Another alternate process con- sists of 2 R0 systems in series using lower pressure to purify the brackish water to potable level. 70 71 Table 11 Summary of Results (Cartridge Model L6J2) Ions % Water Flux at 25°C % Iona Recovery (gpd/ftz) Rejection + Na 30.6 0.423 87.2 50.3 0.531 85.9 60.3 0.510 83.8 x+ 29.4 0.510 82.0 50.0 0.552 75.2 60.0 0.571 75.7 Ca+2 29.8 0.460 98.5 51.0 0.553 94.0 63.0 0.552 89.1 5032 28.9 0.521 2100 50.3 0.545 99.6 62.3 0.572 97.2 a% Ion Rejection was measured at operating time of 120 min. II. III. IV. 72 9.1 Recommendations More conc. HCl can be added to the synthetic brine to lower the pH to 5.5. This may decrease the precipitation of chemicals. The process using higher system pressure (700- 800 psi) should be tried at 30% water recovery. The process using lower pressure (300-400 psi) with 2 R0 systems in series should be tried. The costs of both processes in II and III should be studied to determine the most suitable process for the brackish water. APPENDICES APPENDIX A DEFINITION OF TERMS APPENDIX A DEFINITION OF TERMS Definition of terms used in describing the oper- ation of reverse osmosis process are as follows: Feed stream.--An aqueous solution from which the water is to be removed. Product or permeate stream.--The water which has permeated through the membrane. Concentrate stream.--The aqueous solution which has had part of its water content removed. Concentrate flow rate.--The rate of flow of con- centrate stream expressed in term of gpm. Permeate flow rate.--The rate of flow of product stream expressed in term of gpm. Permeate flux.--The quantity of water permeating through a unit membrane surface during the time interval. This term is expressed as gal.of permeate water per sq. ft. of membrane surface per day. Feed pressure.--The pressure applied to pump the feed stream into the filter (psi). 73 74 System pressure.--The pressure applied to the feed stream before going through the R0 module (psi). Concentrate pressure.--The pressure measured at the concentrate stream after passing through the R0 module (pSi). % Water recovery.--The percentage of permeate water produced in a unit time period on the basis of the feed water used in the same unit time period. Permeate flow rate Permeate flow rate + Concentrate fIOw rate % Water recovery = % Ion rejection.--This term is used to measure process efficiency. (Conc. of ions in feed-Conc. of ions in product) X 100 Conc. of ions in feed % Ion rejection = CA ratio.--This term is used to measure the accuracy of the results. (Feed rate) (Feed activity) - (Permeate rate) (Permeate activity) (Concentrate rate) TConcentrate activity) CA ratio = APPENDIX B ANALYSIS OF TAP WATER FROM MICHIGAN STATE UNIVERSITY APPENDIX B Table 12 Analysis of Tap Water from Michigan State Universitya Constituent Concentration (ppm.) Ca as CaCO3 310. Mg+2 27. -2 SO4 15. Na+ 13.8 C1” 3.0 K+ 1.5 F- 1.0 Fe+2 0.0 Mn+2 0.0 NO3 0.0 Total dissolved solids 371.3 PH 7.6 aThe analysis is from the State of Michigan Department of Public Health (30). 75 APPENDIX C ANALYSES OF THE MARSHALL FORMATION UNDERGROUND WATER APPENDIX C Table 13 Analyses of the Marshall Formation Underground Water Constituent Concentration (ppm.) Ca(HC03)2 1537a Fe(HCO3)2 27 Mg(HCO3)2 329 K2804 213 8102 57 NaCl 4575 NaHCO3 1601 Nazso4 429 Total solids 8768 aThe analysis was found in the U.S. Geological Survey water supply paper No. 31, pages 38, 58 and 60 (1900) (4). The above analysis corresponds to the synthetic brine analysis used in the experiment (excluding Si02). 76 APPENDIX D NEUTRON ACTIVATION AND RADIOACTIVE DECAY APPENDIX D Neutron Activation The Na and K radionuclides used in the experi- ment were activated by MSU Triga Reactor at Michigan State University. The activity produced in an irradiation time t is given by (29): where: 1/2 A At N00 (l-e- ) . . . . . . .(6) activity produced (disintegration/sec. or dps) the no. of atoms of the target nuclide in the sample, capable of forming the radio- isotope in question the neutron flux (n/cm.2-sec) the isotopic thermal neutron capture cross section (cm.2) irradiation time decay constant = 0.693/tl/2 the half life of the nuclear species pro- duced, in the same units as t. 77 78 Radioactive Decay The decay of radioactive nuclides is a first- order reaction in which the rate of change is pro- portional to the number of radioactive atoms present. The number of radioactive atoms present at any time t can be calculated by the following equation (28): A = A e—At O O O O O O O (8) o where: A = no. of radioactive atoms remaining at time t A0 = original no. of radioactive atoms present A = decay constant = 0.693/tl/2 t = half life of the radioactive nuclide 1/2 APPENDIX E RADIOACTIVITY DATA APPENDIX E Radioactivity Data Data of radiactivity counted by the Scintillation Spectrophotometry for all streams (feed, permeate and concentrate) at different times. The activities are net counts per 50 minutes, corrected for background and radioactive decay. 1. Nuclide - S35 Experiment 1 Time (min.) Feed Permeate Concentrate 90 14699 11157 20238 120 13709 10979 21804 150 14647 8791 17004 Experiment 2 30 10459 3111 15870 60 11062 3133 18621 90 10922 3138 20210 120 11119 3170 20002 150 10947 3039 20803 Experiment 3 30 7231 1802 8303 60 7494 2130 12101 90 7426 2450 11958 120 7688 2328 12456 150 7443 2265 12450 Experiment 4 30 2250 130 --- 60 2435 49 1341 90 7966 90 11435 120 8606 56 13352 150 9210 0 14778 79 Experiment 5 Time (min.) 30 60 90 120 Experiment 30 60 90 120 Experiment 30 60 90 120 Experiment 30 60 90 120 Experiment 30 60 90 120 Experiment 30 60 120 180 240 15 28 Feed 12906 15259 15773 15223 7153 7740 5964 5358 11461 16111 16035 15734 2613 2437 2323 2358 8325 7319 6949 7705 16005 16149 16896 15557 12530 Permeate 122 357 201 259 82 296 171 24 371 794 637 446 0000 235 91 150 137 2234 2211 1926 1771 1276 Concentrate 13093 25397 25838 26030 7549 13485 13800 13345 9749 33534 33595 33899 2945 3136 2847 3218 12378 12788 12705 12673 24220 27103 29371 29017 22166 2. Nuclide - Ca Experiment 9 Time (min.) 30 60 90 120 Experiment 10 30 60 90 120 Experiment 11 30 60 90 120 Experiment 17 Experiment 12 30 60 90 120 Experiment 13 45 Feed 6831 8129 8431 8316 8627 9692 10440 10466 4104 4483 4551 4620 1467 10924 10734 11121 Na24 1705 1672 1807 1527 44411 47938 37043 37711 81 Permeate 406 733 303 503 867 1007 1192 1137 307 195 148 71 226 1435 1331 1087 306 348 344 213 7830 5129 5726 6093 Concentrate 5976 14828 15075 15206 17138 21208 23298 23539 7221 7455 6112 6229 5731 18482 18436 18792 2719 3092 2723 2704 79702 73181 71371 73677 Experiment 14 Time (min.) 30 60 90 120 Experiment 16 30 60 90 120 4. Nuclide - Experiment 18 30 60 90 120 Experiment 19 30 6O 90 120 Experiment 20 30 60 90 120 Experiment 21 3O 60 90 120 K 42 Feed 21105 19052 17443 17566 6362 5868 5302 5023 34036 34837 25902 30526 33518 15660 3501 10919 6159 4061 8852 18710 36059 16059 8882 38051 82 Permeate 2689 2555 2271 2245 1146 1231 1033 965 6364 6639 4928 5733 6719 5877 271 4023 465 1070 3110 2935 6346 3522 4421 3701 Concentrate 28417 26415 23611 23532 10617 10618 9538 9276 52206 56231 46785 60565 44246 51492 6648 51778 1296 5511 21225 18216 41844 43731 57631 31598 Experiment Time (min.) Experiment 30 60 90 120 Experiment Experiment 30 60 90 120 Experiment 30 60 90 120 Experiment 22 23 24 25 26 27 Feed 14223 11017 9170 13829 26659 20640 27575 20121 18973 11681 3354 30054 31402 30361 31395 38088 40048 39944 34726 34348 35075 34751 28307 83 Permeate 1971 1809 2023 1904 5879 3389 3838 2772 6282 3462 4147 6060 5883 5347 5652 9696 9526 9136 8620 9370 9650 9268 6894 Concentrate 19238 17135 18097 17949 50147 42785 44380 30838 39339 22355 29950 3186 38904 40152 39730 40194 59824 63217 65857 60832 54112 59320 48050 48421 APPENDIX F SAMPLES OF CALCULATION APPENDIX F Samples of Calculation Samples of Calculation: Experiment 14. - Na+ at 30% water recovery 1. Amount of chemical to be irradiated for experimental 1188:. 45 pCi = 45 x 3.7 x 104 dps. Approximate activity desired (A) Neutron flux (¢) 2 x 1012 n/cmz-sec Isotopic thermol neutron capture cross section of Na24 (0) = 5.3 x 10.25 cm.2 Irradiation time (t) = 1/4 hr. A of Na24 = 4.62 x 10'2 /hr From A = Noo (J.-e’0'693t/t 1/2) 4 « gms. pure Na needed = (45 x 3'7 x 10 ) (23) (6.023 x 1023) (2 x 1012) _2 (5.3 x 10'25) {1-e'("'°62 X 10 /4)} = 5.216 x 10‘3 3 ; gms. NaOH needed =(%§9 (5.22 x 10— ) = 9.071 x 10’3 gms. 2. Radioactive decay after 600 min. or 10 hr.: Activity after 10 hr. (A) = 11067 counts/50 mins. t 10 hr. From A0 = AeAt 84 85 4.62 x 10'2 x 10 (11067) (e ) 1 Initial activity 17566 counts/50 mins. 3. % Ion rejection: (Feed Activity-Permeate Activity) Feed Activity x 100 % Ion rejection (17566 - 2245) 417566 x 100 4. Permeate flux: Permeate flux rate ;_ Active membrane area of RO module a) Permeate flux at T°C = (0.435 gpm) (60 min) (24 hr.) (1895 ftz) (1 hr.) (1 day) 0.330 gpd/ft2 Flux at temperature T°C b) Permeate flux at 25°C = T-T (1.0265) 25 0.330 = 0.423 gpd/ft.2 5. % Water Recovery: = Permeate flow rate x 100 , Feed flow rate Permeate flow rate x 100 Permeate flow rate + Concentrate flow rate _ 0.44 ‘ 0.44‘4 0.99 X 100 = 30.6% 86 6. CA ratio: (Feed rate) (Feed activity) - (Permeate rate) jfi (Permeate activity) (Concentrate rate) (Concentrate activity) (1.43) (17566) - (0.44) (2245) (0T99) (23532) = 1.03 7. Standard deviation (0): The standard deviation of a net number of counts is the square root of the number of counts divided by the length of time the sample was counted. 1/2 - 0Feed = ($1599) = 2.651 Cpm. .. 50 1/2 0Product = (Eééé) = 0.948 Cpm. The standard deviation of the difference of two numbers is given as follows in counts per minute (cpm.): (A 1' OF) " (B 1 Up) = (A-B) i (O; + 0:)1/2 = (A-B) i ODIF 17566 2245 + 17566 2245 1/2 ( ’ ) — ( + -——-4 56 55 502 502 306.420 i 2.815 cpm. The standard deviation of a quotient is given as follows in cpm: |+ “'3 ODIF) F H 3 The standard 87 2 o o 2 (.5712) [1 i {ELF—2.... F }1/2] (A-B) A 306.4202 (17566 50 ( 17566 2 17566 - 2245) [l + { 2.815 + 2.651 0.872 t 0.012 deviation of this quotient is 1.2%. 2 ) 1/2 2}] BIBLIOGRAPHY BIBLIOGRAPHY Kaup, Edgar C. "Design Factors in Reverse Osmosis." Chem. Eng., April 2, 1973, 47-55. Breton, E. J., Jr. and Reid, C. E. "water and Ion Flow Through Imperfect Osmotic Membranes." Office of Saline water Research and Development Progress Report No. 16, April, 1957. Loeb, S. and Sourirajan, S. Advan. Chem. Ser., 38 (1962), 117. Lansing Board of Water and Light. Report of C. R. Erickson to O. E. Eckart, General Manager, October 25, 1954. Tucker, Lanny J. "An Investigation of the Purifi- cation of Synthetic Brine with Reverse Osmosis." M.S. Thesis, Michigan State University, Dept. of Chem. Eng., E. Lansing, Mich. (1972). Merten, U. Proceedings of the First International Symposium on water Desalination, Washington, D.C., October 3-9, 1965, l (1967), 275. Hittman Associates. "Reverse Osmosis Desalting State-of-the—Art (1969)." Office of Saline Water Research and Development Progress Report No. 611, October, 1970. Dow Chemical Company. "Development of Cellulose Triacetate Hollow Fiber Reverse Osmosis Modules for Brackish Water Desalination." Office of Saline Water Research and Development Progress Report No. 763, December, 1971. Lonsdale, H. K., Merten, V. and Riley, R. L. "Trans- port Properties of CA Osmotic Membranes." Appl. Polymer Sci., 2 (1965), 1341. 88 10. 11. 12. 13. 14. 15. l6. 17. 18. 19. 20. 21. 22. 89 Rickles, R. N. "Molecular Transport in Membranes." Ind. Eng. Chem., §§_(6) (1966), 19. Sarbolouki, M. N. and Miller, Irving F. "On Pore Flow Models for R0 Desalination." Desalination 12 (1973), 343. Yasuda, H., Lamaze, C. E. and Peterlin, A. "Dif- fusive and Hydraulic Permeabilities of Water in Water Swollen Polymer Membranes." J. Polymer Science, 2_(1971), 1117. Yasuda, H. and Lamaze, C. E. "Salt Rejection by Polymer Membranes in R0. I. Nonionic Polymers." ibid., 2_(197l), 1537. Yasuda, H. and Lamaze, C. E. "Salt Rejection by Polymer Membranes in R0. II. Ionic Polymers." ibid., 9 (1971), 1579. Spiegler, K. S. and Kedern, A. "Thermodynamics of Hyperfiltration (RO): Criteria for Efficient Membranes." Desalination, i (1966), 311, Johnson, J. 8., Jr., Kraus, K. A. and Dresner, L. Principles of Desalination, K. S. Spiegler, Ed., Academic Press, New York, N.Y., Chapter 8, 1966. Elata, C. "The Determination of the Intrinsic Characteristics of Reverse Osmosis Membranes." Desalination, 6 (1969), 1. Keilin, B. Office of Saline Water Research and Development Progress Report No. 84, 1963. Sourirajan, S. "The Mechanism of Demineralization of Aqueous Sodium Chloride Solutions by Flow, Under Pressure, Through Porous Membranes." Ind. Eng. Chem. Fundamentals, 3 (l) (1963), 51. Gluekauf, E. Proceedings of the First International Symposium on Water Desalination, Washington, D.C., October 3-9, 1965, l (1967), 143. Lacey, Robert E. "Membrane Separation Processes." Chem. Eng., September 4, 1972, pp. 56-73. "Polymetrics Operational Manual." Prepared for Model 803005, Serial 1175 Reverse Osmosis System of Dow Chemical Company. 23. 24. 25. 26. 27. 28. 29. 30. 90 Chemical Analysis from Dow Chemical Laboratory. Reported in the letter from Mr. Jerry T. West- brook of Dow Chemical Company, Midland to Dr. Bruce W. Wilkinson, MSU, November 23, 1971. Jackson, James M. and Landolt, Dieter. "About the Mechanism of Formation of Iron Hydroxide Fouling Layers on Reverse Osmosis Membranes." Desalin- ation, 12 (1973), 361. Packard Operation Manual for Series 3000 Tri-Carb Liquid Scintillation Spectrometer System Manual 2018, Packard Instrument Co., Inc., LaGrange, Ill., March, 1964. Milstead, C. E., Reidinger, A. B. and Lonsdale, H. K. "Rejection of Carbon Dioxide and pH Effects in Reverse Osmosis Desalination.“ Desalination, 9 (1971), 217-23. Chase, G. D. and RabinnoWitz, J. L. "Scintillation Techniques and Nuclear Emulsions.” Principles of RadioisotOpe Methodology, 3rd Ed., Burgess Pub- lishing Company, Minneapolis, 1967, pp. 283-323. Chase, G. D. and Rabinnowitz, J. L. "Radioactive Decay." Ibid., pp. 146-85. Chase, G. D. and Rabinnowitz, J. L. "Activation AnalYSiSo I! Ibido ’ pp. 427-320 Chemical Analysis of Water from Michigan Department of Public Health, Bureau of Laboratories, Lab. No. 441, February 1, 1972. 498 579 lllll ”0 U“ ummmwljlwum 3