膜分离(组件)

1、membranes膜过程的驱动力压力驱动- RO, NF，UF, MF其它过程-渗析（浓度差）电渗析（电位差）压力驱动的膜过滤膜 MF UF NF RO孔尺寸减小泵压力增加 高分子材料 (PAN, PES, CA, PVDF). 铸膜液制备：聚合物+有机溶剂(NMP, DMF, acetone等易与水互溶). 添加其它助剂 (pore-formers or non-solvents). 凝固浴 （主要用水和其它聚合物不良溶剂构成，通过相分离产生the pores 和the membrane body)必需品 PES聚合物 NMP 溶剂 水 玻璃片 刮膜器 NMP甲基吡咯烷酮PES聚醚酚Poly

2、 Sulfon (PS)PS in NMP solutionCleaning glassplates importantglassplatesFilling the knife with PS solutionMembrane knife (0,2 mm)Creating a membrane filmPut slowly in the water for.Move very gently to leftMembrane is floating after coagulationAfter coagulationTake of a membraneOut of the waterThe pho

3、to of the produced membraneMake sheets of it in a moduleMake a module of itMore than one membraneSubmerge in a MBR tank Porous vs Non Porous Hydrophilic vs Hydrophobic Polymeric vs InorganicHydrophilic亲水 Hydrophobic疏水Porous Non PorousSymmetric Asymmetric Dense (Non porous)Porous SymmetricPorous asym

4、metricRO, NFUF, MFMFSkinSupportPorous Symmetric MembranesNuclepore Membrane核径迹成孔核径迹成孔Cellulose MembraneSymmetric membraneAsymmetric MembranesDense LayerPorous supportFiber SupportPore sizeCeramic membrane pictures (CEM)Membrane structure structure: symmetric asymmetric shapes: flat sheet tubular: tu

5、be(d 3 mm) capillary (0.5 d 3.0 mm) hollow fibre(d 0.5 mm)Module shapes Flat Sheet Spiral Wound Tubular Hollow Fiber Contained vs SubmergedFlat sheet moduleMembraneFeedResiduePermeatePermeate014-DWG-MWPlate and Frame ModuleUFPolyacrylo nitrile(PAN)Polyvinylidene fluoride(PVF)Polysulfone(PS)Sulfonate

6、d Polysulfone(SPS)Tubular and capillary membranes Tubular membranewww.vito.beTubular membranes (contained)Hollow Fiber (capillar)Outside In VS Inside OutFrom Catalog of TorayCapillary 8 inch moduleMonolith (demo)Inorganic Membranes- CeramicMF, UFRecently NF- Porous glass- ZirconiumSpiral-Wound RO/NF

7、 ModuleFlow INSpacerMembranePermeateConcentrateCollection pipeFeed flowFeed flowPerm eate flowMem braneMem braneFeed spacerFeed spacerResidue flowPerm eate015-DW G-MWYou can make your own spiral wound module today! Two A4 papers Cotton sheet A4 (if available) Shears to cut Glue for paper Plastic tub

8、e with a slid (prefabricated)Reverse Osmose-installation+/- various configurationsFeedPermeatePermeateFeedRetentateDead endCross-flowDeadend and CrossflowOperation modesMembrane filtration dead-endMembraneWaste waterPermeatefeedMembrane filtration cross flowWaste waterPermeateconcentratefeedmembrane

9、Air injectionDead-end FiltrationtimeCross-flow filtrationtimeSemi dead-end filtrationCross-flow filtration Advantages:turbulent flowcontinuous concentrate dischargecontrol of cake-layer build-up Disadvantages:more complex process layouthigh(er) energy consumptionhigh(er) investment costCascade singl

10、e pass systemFeedRetentateConcentrateTwo-stage recirculation systemConcentrateFeedPermeatePermeateStage 1Stage 2Feed pumpRecirculation pumpFouling of membranes Fouling Reversible fouling Irreversible fouling Biofouling Pore blocking Scalingfoul a.1. 肮脏的,污浊的;2. 恶臭的;(食物)腐败的;3. 邪恶的,可恶的;4. 下流的,恶语咒骂的;5.

11、(天气等)恶劣的;(风)逆的;6. (比赛中)犯规的;7. (水管等)堵塞的;8. (绳索等)被缠住的ad.1. 违反规则地;不正当地n.1. (比赛中)犯规C(+against/on)vt.1. 弄脏;污染;玷污;2. 使堵塞;3. 缠住;4. 碰撞vi.1. 腐败,腐烂;2. (管道等)堵塞(+up);3. (比赛中)犯规;4. (绳索等)缠结Resistance ModelI =ER1+R2+R3ER1R2R3IRmRcRgRpJvJv =DPm(Rc+Rg+Rp +Rm)Separation of resistance factors to Cake, Gel, Plugging, M

12、embrane.Rejection by UF/MF membranesGlobular ProteinLinear polymerSolutePepsinCytochrome CPolydextranMW (kDa)3513100Rejection (%)90700 Porous supportSelective membrane skinGlobularproteinLinearmacromoleculeCake layer formationMembraneParticleColloid/proteinCake/fouling layerFlow directionDriving for

13、cepFouling in MF/UFDecrease in flux due to: Pore-plugging, adsorption and cake-layer formation No concentration polarization of salts no scaling In general concentrated feed solutions containing large particles (size 10 nm 25 m).This results in low back-diffusion rates, fast cake layer build-up and

14、pore blocking low product-fluxes (1/10 of the CWF) Complex cake layer structureFouling in NF/ROFouling behavior differs from UF/MF due to: Lower fluxes and presence of smaller molecules higher back-diffusion and in general no thick cake layer formation Charged membrane surfaces (in general negative)

15、 adsorption of colloids and biological matter Scaling (CaSO4, CaCO3)Fouling reduction/cleaning Membrane properties and module design Optimum process conditions (low TMP) Cleaning regimehydraulic cleaning (backwash, forward flush and airflush)chemical cleaningrelaxation Pre-treatment of the feed (flo

16、cculation/coagulation, pH adjustment)Backwash (= Backflush)SuspensionMembranePermeateFiltration modeBackflushing modeto drainFluxTimewith backflushingwithout0negative flowSuspensionMembranePermeateFiltration modeBackflushing modeto drainFluxTimewith backflushingwithout0negative flowBackwash (= Backf

17、lush)Forward Flush productionforward flushBack Flush productionforward flush & back flushpermeateAirFlushbubble flowslug flowannular flowForward Flush with airflush productionforward flush with airflush & backflushMembrane filtration semi dead-endMembraneWaste waterPermeatefeedDead-end production-ru

18、n, startpermeatepermeatepermeatepermeatefeedMembrane moduleDead-end at end of production runBuilding up fouling layerProduction of permeate decreases at constant TMPpermeatepermeatepermeatepermeatefeedDead-end with backflushBackflush with permeate duringproductionconcentratefeedpermeatepermeateperme

19、atepermeateDead-end with backwash & airflushAir injectionfeedpermeatepermeatepermeatepermeateBackwash with airflush results in lower permeate useAir injectionMembrane filtration cross flowWaste waterPermeateconcentratefeedmembraneAir injectionCross flow High sheering forces in membrane module Low fouling layer build up Higher energy demand Higher recovery Applicated for higher MLSS contentsAt t = 156 hAt t = 372 hThe effect of backwash on permeate production:Relaxation Give the membrane time to relax Fouling will loosen Me