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Membrane FiltrationRanjan Sharma1www.OzScientific.com

Traditional vs membrane filtrationTraditional2Membrane

Membrane filtrationAPV3

Batch membrane filtration plantFeed productConcentration loopPermeateCooling medium1. Product tank2. Feed pump3. Circulation pump4. Strainer5. Membrane module6. CoolerDairy Processing Handbook. Published by Tetra Pak Processing Systems AB, S221 86 Lund, Sweden.4

Membrane filtration spectrumDairy Processing Handbook. Published by Tetra Pak Processing Systems AB, S221 86 Lund, Sweden.5

Filtration spectrumGEA6

Membrane filtration - dairyDairy Processing Handbook7

Filtration processes - dsWaterBacteriaionsMFUFNFRO8

Membrane filtration applications Reverse osmosis (RO) Concentration of solution by removal of water Concentration of organic components by removal of part ofmonovalent ions like sodium and chlorine (partialdemineralisation) Nanofiltration (NF) Ultrafiltration (UF) Concentration of large and macro molecules Removal of bacteria, separation of macromolecules Microfiltration (MF)9

Comparison of membrane processesWagner, 2001, Membrane Filtration Handbook10

Wagner, 2001, Membrane Filtration HandbookApplications of membrane filtration11

Membrane material Membranes may be composed of natural (e.g modifiednatural cellulose polymers ) or synthetic polymers (plasticmaterials) or inorganic ceramic materials 12be good film formers,manage high permeate flows,have high selectivity,have good chemical and bacteriological resistance,be resistant to detergents and disinfectants,be inexpensive.

Membrane material – cellulose acetate Mostly for RO and UF Advantages easy to manufacture, provide high flux and have high saltrejection properties Disadvantages 13limited temperature range (max 30 C),limited pH range (pH 3-6) – problem for cleaning withdetergentspoor resistance to chlorine as a sanitiser,poor membrane properties at high operating pressuressusceptibility to microbial attack due to their natural origin

Membrane material – synthetic polymers 14Polyamide and polysulphoneWidely used for UFWide tolerance to pH, temperature and chlorine

Membrane material – ceramic 15Made from mineral materials such as glass,aluminium oxide and zirconium oxideHigh resistance to chemical degradation, andtolerate wide pH and temperature rangesExpensive and can be brittleMainly used for microfiltration

Chemical resistance of membrane materialWagner, 2001, Membrane Filtration Handbook16

Membrane manufacturersWagner, 2001, Membrane Filtration Handbook17

Membrane modules 18Plate and frameSpiral woundTubular, based on polymersTubular, based on ceramicsHollow-fibre

Plate and frame design 19Membrane sandwiched between membranesupport plates which are arranged in stackssimilar to a plate heat exchangerTypically polymers (e.g polyethersulfone) withpolypropylene or polyolefin supportUF ( 1 to 1000 kDa MWCO)MF (0.1 to 0.16 um diameter)

Plate and frame membrane systemsRetentatePermeateFeedOval shapedRectangle shaped20

Plate and Frame moduleNirosoft waste water system21http://www.nirosoft.com/site/item.php?ln en&item id 189&main id 110

Plate and Frame moduleNirosoft waste water system22http://www.nirosoft.com/site/item.php?ln en&item id 189&main id 110

Spiral Wound membraneWagner, 2001, Membrane Filtration Handbook23

Spiral Wound membrane – cross-section24

Hollow fibre membrane Hollow-fibre a narrow tube made of anon-cellulosic polymerwww.norit.nl25

Hollow fibre membranewww.tifac.org.in26

Hollow fibre membrane27

Tubular design - polymers Stainless steel tubes in 28shell and tubeconstructionMembrane insertPCI – Patterson andCandy International

Tubular design - ceramic Channels fine-grained ceramic Support Coarse-grained ceramic Applications removal of bacteria frommilk, whey, WPC, brine French company - SCTDairy Processing Handbook29

Comparison of membrane modulesSystemAdvantagesFlat Sheet/ 1. Low hold up volumePlate and 2. Permeate from individualFramemembrane element3. Membrane replacement easyDisadvantages1. Difficult to clean2.Susceptible to pluggingSpiral1. Compact1.Not suitable for very viscous fluidWound2. Minimum energy consumption 2.Dead spaces3. Low capital/operating cost3. Difficult to clean4.Faulty membrane - change whole moduleHollowFibre1. Low hold up volume2. Backflushing possible3. Low energy consumption1. Susceptible to end-face fouling2. Not suitable for viscous fluids3. Single fibre damage - replace entire moduleTubular1. Feed stream with particulatematter can be put throughmembrane2. Easy to clean1. High energy consumption2. High hold-up volume30

Comparison of membrane modules31Wagner, 2001, Membrane Filtration Handbook

Filtration modulesRONFUFSpiral-wound Plate and frame Tubular (polymers) Tubular (ceramics) Hollow-fibre 32Dairy Processing HandbookMF

Membrane structure Asymmetric Same material throughout, but has a thin, tight skin on thesurface of the feed side so that the skin is the effective filtrationlayer, and the more open and thicker sub layer serves as asupport for the skinMost widely used for both UF and RO Same material with the same structure throughout A thin polymer membrane on a microporous sub layer ofanother material Symmetrical Composite asymmetric membranes33

Batch operationEnergy inefficient34

Continuous operation with single passNot practicalToo large area requirement35

Continuous operation feed and bleed36

Multistage operation37

Factors affecting membrane performance fouling Concentration polarisation Differential solute conc between membrane surface and bulk streamReversibly affected by operation parametersFouling Formation of deposits Irreversibly affected by operation parameters38

Concentration polarisation39

Membrane fouling Two types Surface (temporary) fouling Pore (permanent) fouling40

Membrane fouling Surface (temporary) fouling Foulant appears an evenly deposited layer on the 41membrane surfaceCan be easily removed by cleaning solutionPermeation rate of membrane can be regenerated bycleaningMost common type of fouling in UF plantMost studies dealt with this type of fouling

Membrane fouling Pore (permanent) fouling Particulate matter diffuses into the membrane Could be caused by the poor quality of the cleaning 42waterUneven distribution of the foulant and compression ofthe separation zoneFlux cannot be regenerated by cleaningDetermines the lifetime of the membraneReceived much less attention in literature

Membrane fouling Implications More energy consumption Duration of continuous operation without need for 43cleaningMembrane durabilityProperties and quality of concentrateOverall economy of the membrane process

Ultrafiltration 44Can be defined as a pressure-driven membraneprocess that can be used in separation andconcentration of substances having a molecularweight between 103 – 106 DaltonsMost widely used in dairy industry

Applications of UF in dairy industry Protein standardisationMilk solids fortification for yogurtCheese Whey protein concentrate and isolate (WPC/WPI) Milk protein concentrate and Isolate (MPC/MPI)45 Increased yield Protein concentration Protein concentration

Five fold concentration of milk by UFMilkComponent% Fat% Protein% Lactose% Salts% Total Solids% Water46Feed Retentate/Permeate100 L MilkConcentrate 20L 04.80.75.594.5

UF – Commercial UF plant set upDairy Processing Handbook47

WPC 48UF spiral-wound membrane MW cutoff: 10000 Da DF required for higher than 60% protein

Whey protein concentrate35-85% protein in dry matter 49UF : 25-30% solidsMF to remove fatDF to remove more lactose and mineralsSpray drying

WPI ( 90% protein) UF/DF Microfiltration to remove fat50

WPC manufacture51

WPC – Whey compositionTotal oferrin52Sweet wheypH:6.2-6.4Acid wheypH: 4.6-5.0

WPC To increase flux Demineralisation Calcium removal 53(electrodialysis)Sequestering agent (SHMP)Increase pH to 7.5 (calcium phosphateprecipitate)Preheating 60 C for 30 min; UF at 50 CMicrofiltration

Effect of diafiltration on Diluted50:50with water40L .020.00.0Protein%17.58.7517.50.0Lactose %4.82.42.42.4Salts0.70.350.350.35Total Solids%43.021.540.252.75Water57.078.558.7597.25%%

Modern WPC plantFeed flow – 100,000 L/h constant feed rateTemperature - cold55

Milk protein concentrate Concentrating both casein and whey proteinsRatio similar to milkApplications: Cheese milk extension Nutritional beverages56

MPC CompositionComponentsNFDMMPC-56 MPC 75MPC 80(% 21.51.7Lactose51.33110.95.5Minerals7.78.08.27.457

MPC Manufacturing ProcessPasteurization/UHTRaw ionCreamWaterUF/EV concentrateSkimmilkmilkSkimUltra/diafiltrationUF Concentrate58WaterPermeateSpray DryingMPCWater

UF in cheese making Protein standardisation 3.6-4.0% Consistent cheese quality Increased throughput Open structure cheeseModified equipment needed Suitable for closed structure cheeseModified equipment needed Pre-concentration – 2X Partial concentration 20% and 40% TS Total concentration59

Applications of UF in dairy industryDairy Processing Handbook60Tilsiter cheese using ultrafiltration

Reverse osmosis Osmosis Pure water flows from a dilute solution through asemipermeable membrane(water permeation only) to ahigher concentrated solutionRise in volume to equilibrate thepressure (osmotic Water

Reverse osmosis Reverse osmosis If pressure greater than the osmoticpressure is applied to the highconcentration the direction of waterflow through the membrane can bereversed.http://www.trionetics.com/an001.pdf62

Reverse osmosishttp://www.trionetics.com/an001.pdf63

Reverse osmosis 643-10 MPaRemove water against osmotic pressureΠ 0.7 MPaWater and small molecules diffuse through30% dry matter achievableGel layer formed by caseinWhey proteins at pH 6Calcium phosphate a problem at pH 6.6

Reverse osmosis Milk - Can be used for concentration up to 30% TS Fat globules increases viscosity Homogenization in retentate through the pressure 65release valveLactose crystallizationApplied to permeate from UF or whey

Whey powder - RO Separation of fat and casein fines Pasteurization Concentration Reverse osmosisVacuum evaporation (45-65%)(Lactose crystallization) Spray drying66

Nanofiltration (NF) 67New class of pressure-driven membraneprocesses that lies between UF and ROPressure range - 10-50 barRejects ions with more than one negative charge(such as SO42- , CO32-)

Nanofiltration Removal of inorganic salts Na, K, Cl, urea, lactic acid, Partial demineralization Membranes that leak particle species with a radius in thenanometer range 68Reduce salty tastePretreatment for electrodialysis, ion exchangeAcid removalReduce salt from cheese making

Lab NF equipment – DDS Lab 20 Plate & Framehttp://www.ivt.jku.at/Lehre/pdf2/04NF PRws2006.pdf69

NF -Salt rejection by different NF membranes - 0.2M NaClΔ - 0.2M Nasulphatehttp://www.ivt.jku.at/Lehre/pdf2/04NF PRws2006.pdf70

NF – rejection at 30 bar at 25CMW 200-1500 Da - 90% rejectedhttp://www.ivt.jku.at/Lehre/pdf2/04NF PRws2006.pdf71

NF - Commercial NF membraneshttp://www.ivt.jku.at/Lehre/pdf2/04NF PRws2006.pdf72

MF - Microfiltration 73Two filter modules connected in seriesOne retentate circulation pumpOne permeate circulation pump

MF – industrial two module MF system 74Dairy Processing HandbookTwo filter modulesconnected in seriesOne retentatecirculation pumpOne permeatecirculation pump

MF – Design principle of MF filter loopDairy Processing Handbook75

MF - Hollow fibre designA – filtrationB – Back flushingC - CleaningDairy Processing Handbook76

GEA Filtration77

MF - buttermilkMF (0.8 um) 50C; 25C; ¡7CJ Dairy Sci 2004, 87, 26778

MF - buttermilkMF using 0.8 um membraneJ Dairy Sci 2004, 87, 26779

Other membrane techniques 80Counter diffusionOsmotic distillationElectrodialysisIon-exchange

Counter diffusion81Separate small ions from large moleculesHollow fibre cellulose diffusion tubesCounter diffusion can produce 50% demineralisationwhich may represent 70% removal of monovalents

Osmotic distillationLow pressure and low temp separationHollow fibre or spiral wound hydrophobic membrane82

ElectrodialysisUses electrical force to separate charged particles83