FilmTec Technical Manual - Chester Paul Company

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Figure 1.1 Major desalination processes8,000Brackish Water RO Membranes50 12,000Distillation20,000Sea Water ROMembranes50,000105050Low Energy BW RO MembranesIon Exchange3006002,000Reverse OsmosisElectrodialysis10,000Raw Water Salt Concentration (mg/l)50,000100,000The various filtration technologies which currently exist can be categorized on the basis of the size of particles removed froma feed stream. Conventional macrofiltration of suspended solids is accomplished by passing a feed solution through the filtermedia in a perpendicular direction. The entire solution passes through the media, creating only one exit stream. Examples ofsuch filtration devices include cartridge filters, bag filters, sand filters, and multimedia filters. Macrofiltration separationcapabilities are generally limited to undissolved particles greater than 1 micron.For the removal of small particles and dissolved salts, crossflow membrane filtration is used. Crossflow membrane filtration(see Figure 1.2) uses a pressurized feed stream which flows parallel to the membrane surface. A portion of this streampasses through the membrane, leaving behind the rejected particles in the concentrated remainder of the stream. Sincethere is a continuous flow across the membrane surface, the rejected particles do not accumulate but instead are sweptaway by the concentrate stream. Thus, one feed stream is separated into two exit streams: the solution passing through themembrane surface (permeate) and the remaining concentrate stream.Figure 1.2 Crossflow membrane filtrationThere are four general categories of crossflow membrane filtration: microfiltration, ultrafiltration, nanofiltration, and reverseosmosis.Microfiltration (MF)Microfiltration removes particles in the range of approximately 0.1 to 1 micron. In general, suspended particles and largecolloids are rejected while macromolecules and dissolved solids pass through the MF membrane. Applications includeremoval of bacteria, flocculated materials, or TSS (total suspended solids). Transmembrane pressures are typically 10 psi(0.7 bar).Ultrafiltration (UF)Ultrafiltration provides macro-molecular separation for particles in the 20 to 1,000 Angstrom range (up to 0.1 micron). Alldissolved salts and smaller molecules pass through the membrane. Items rejected by the membrane include colloids,proteins, microbiological contaminants, and large organic molecules. Most UF membranes have molecular weight cut-offvalues between 1,000 and 100,000. Transmembrane pressures are typically 15 to 100 psi (1 to 7 bar).Page 8 of 180 ® Trademark of The Dow Chemical <strong>Company</strong> ("Dow") or an affiliated company of Dow Form No. 609-00071
Nanofiltration (NF)Nanofiltration refers to a speciality membrane process which rejects particles in the approximate size range of 1 nanometer(10 Angstroms), hence the term “nanofiltration.” NF operates in the realm between UF and reverse osmosis. Organicmolecules with molecular weights greater than 200-400 are rejected. Also, dissolved salts are rejected in the range of 20-98%. Salts which have monovalent anions (e.g. sodium chloride or calcium chloride) have rejections of 20-80%, whereassalts with divalent anions (e.g. magnesium sulfate) have higher rejections of 90-98%. Typical applications include removal ofcolor and total organic carbon (TOC) from surface water, removal of hardness or radium from well water, overall reduction oftotal dissolved solids (TDS), and the separation of organic from inorganic matter in specialty food and wastewaterapplications. Transmembrane pressures are typically 50 to 225 psi (3.5 to 16 bar).Reverse Osmosis (RO)Reverse osmosis is the finest level of filtration available. The RO membrane acts as a barrier to all dissolved salts andinorganic molecules, as well as organic molecules with a molecular weight greater than approximately 100. Water molecules,on the other hand, pass freely through the membrane creating a purified product stream. Rejection of dissolved salts istypically 95% to greater than 99%.The applications for RO are numerous and varied, and include desalination of seawater or brackish water for drinkingpurposes, wastewater recovery, food and beverage processing, biomedical separations, purification of home drinking waterand industrial process water.Also, RO is often used in the production of ultrapure water for use in the semiconductor industry, power industry (boiler feedwater), and medical/laboratory applications. Utilizing RO prior to ion exchange (IX) dramatically reduces operating costs andregeneration frequency of the IX system. Transmembrane pressures for RO typically range from 75 psig (5 bar) for brackishwater to greater than 1,200 psig (84 bar) for seawater.The normal range of filtration processes is shown in Figure 1.3.Figure 1.3 Ranges of filtration processesPage 9 of 180 ® Trademark of The Dow Chemical <strong>Company</strong> ("Dow") or an affiliated company of Dow Form No. 609-00071
Page 1 and 2: DowWater SolutionsFILMTEC Reverse O
Page 3: 2.6 Biological Fouling Prevention .
Page 7: 1. Basics of Reverse Osmosis and Na
Page 11 and 12: How to Use Reverse Osmosis and Nano
Page 13 and 14: 1.4 Membrane DescriptionThe FILMTEC
Page 15 and 16: Membrane systems are typically desi
Page 17 and 18: 1.8 Element CharacteristicsFILMTEC
Page 19 and 20: 2. Water Chemistry and Pretreatment
Page 21 and 22: SeawaterSeawater with TDS of 35,000
Page 23 and 24: Table 2.5 Water analysis for RO/NFS
Page 25 and 26: Table 2.7 Solubility products of sp
Page 27 and 28: In this process, only Ca 2+ , Ba 2+
Page 29 and 30: For the concentration ranges presen
Page 31 and 32: The conditions for CaCO 3 scale con
Page 33 and 34: Figure 2.3 Langelier saturation ind
Page 35 and 36: These computations have been descri
Page 37 and 38: Figure 2.5 “K” versus ionic str
Page 39 and 40: Figure 2.6 Ksp for CaSO 4 versus io
Page 41 and 42: 2.4.6 Calcium Fluoride Scale Preven
Page 43 and 44: Figure 2.8 K sp for SrSO 4 versus i
Page 45 and 46: 2.4.7 Silica Scale PreventionDissol
Page 47 and 48: Table 2.10 Solubility of SiO 2 vers
Page 49 and 50: 2.4.8 Calcium Phosphate Scale Preve
Page 51 and 52: Table 2.9 Various fouling indicesIn
Page 53 and 54: Frequent shutdowns and start-ups sh
Page 55 and 56: If the differential pressure across
Page 57 and 58: 1. Intake (surface) or well, before
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or combined residual chlorine (CRC)
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2.6.5 DBNPADBNPA (2,2, dibromo-3-ni
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2.6.11 Use of Fouling Resistant Mem
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2.11 Treatment of Feedwater Contain
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2.13 Summary of Pretreatment Option
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26. Handbook of Industrial Membrane
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Table 3.1 System design information
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3.2 Batch vs. Continuous ProcessAn
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3.4 Single-Stage SystemIn a single-
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The apparent salt passage of the sy
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Instead of having a separate high-p
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3.9.1 Membrane System Design Guidel
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In Table 3.6, the small commercial
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Table 3.8 Number of stages of a sea
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3.11 System Performance Projection3
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3.11.2 Design Equations and Paramet
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Table 3.10 Design equations for pro
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3.11.3 Comparing Actual Performance
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The high-pressure concentrate is fe
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If the product water from an RO sys
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Besides the above recommendations,
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4. Loading of Pressure VesselsThis
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The process of shimming is performe
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4.5.2 Summary of Large Element Inte
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5. System Operation5.1 Introduction
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5.2.3 Start-Up SequenceProper start
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5.2.4 Membrane Start-Up Performance
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5.5.3 SeawaterIn principle, the ope
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Table 5.1 Reverse osmosis operating
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A. Normalized Permeate FlowQS=ΔPsP
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For the operating conditions we hav
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4. During recirculation of cleaning
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2. The cleaning pump should be size
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6.7 Effect of pH on Foulant Removal
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Cleaning ProcedureThere are seven s
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If the organic fouling is the resul
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There are two factors that greatly
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7. Handling, Preservation and Stora
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7.4 Preservation of RO and NF Syste
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If the normalized actual performanc
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8.3.3 Localization of High Solute P
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Figure 8.2 Permeate probing apparat
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8.4.5 Performance TestThe standard
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8.5.1.1 Low Flow and Normal Solute
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. Metal Oxide FoulingMetal oxide fo
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. Organic FoulingThe adsorption of
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8.5.3 High Pressure DropHigh differ
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In case of fullfit or heat sanitiza
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Breakpoint chlorinationBreak tankBr
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FeedThe input solution to a treatme
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Milligram per litre (mg/L)Mixed-bed
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SBS Sodium bisulfite, NaHSO 3.Scale
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9.2 Specific Conductance of Sodium
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Figure 9.1 Conductivity of ionic so
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9.6 Temperature Correction FactorTa
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9.9 Osmotic Pressure of Sodium Chlo
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Details - TestEquipment andSpecific
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satisfactory for such a determinati
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case for almost all tested biocides
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9.12 Key Word IndexAbrasion - 150 B
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Positive displacement pump - 95 Shu
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FilmTec Technical Manual - Chester Paul Company

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