Flux enhancement in a spiral wrap ultrafiltration element by using backpulsing

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dc.contributor.advisorBurger, A. J.en_ZA
dc.contributor.advisorSanderson, R. D.en_ZA
dc.contributor.authorElarbi, Abdulghaderen_ZA
dc.contributor.otherUniversity of Stellenbosch. Faculty of Engineering. Dept. of Process Engineering.
dc.dateENGLISH ABSTRACT: The effect of backpulsing on the prevention of fouling of a 2.5 inch spiral wrap cross-flow ultrafiltration element was investigated experimentally. Backpulsing experiments with an organic (dextrin) solution and an inorganic (kaolin) suspension were performed using a polypropylene membrane with 100 000 molecular mass cut point. The dextrin feed concentration ranged from 250 to 750 mg/L, the kaolin feed concentration ranged from 100 to 300 mg/L, the feed flow rate ranged between 500 and 1500 L/h, and the feed pressure was fixed at 100 kPa. Backpulsing involves applying pressure pulses ranging from 100 to 150 kPa on the permeate space. The pulsing interval varied between 1 and 15 s and pulse duration varied between 0.1 and 0.5 s. Experimental results showed that backpulsing was effective in reducing membrane fouling and improving membrane flux. With continual backpulsing the net flux was found to increase with increasing backpulsing pressure, increasing weakly with increasing cross-flow rate and decreasing strongly with increasing feed concentration. The best backpulsing parameters for the respective foulants were found to be the following: 0.2 s pulse duration, 3 s pulse interval and 150 kPa backpulse pressure for the dextrin solution, and 0.2 s pulse duration, 5 s pulse interval and 150 kPa backpulse pressure for the kaolin suspension. The best flux results achieved using backpulsing under these conditions were 3-fold and 1.5-fold higher than the fluxes obtained in the non pulsing case for the dextrin and kaolin feeds, respectively. After the membrane had been exposed to fouling and then backpulsing, it was cleaned, using clean water with backpulsing. The flux values of the clean membrane, previously fouled with dextrin and kaolin were 62% and 71% of the original clean membrane fluxes, respectively. The Taguchi method with L9 orthogonal array was used to identify the influential factors backpulsing that give maximum permeate flux. It was found that pulse pressure has the strongest effect on membrane flux. Pulse interval and pulse duration have negligible effects and, in comparison cross-flow rate has a weak effect on the membrane flux. It must be noted that these observations are only valid within the experimental boundaries, as identified during the preliminary investigation.en_ZA
dc.date.accessioned2009-11-24T08:03:37Zen_ZA
dc.date.accessioned2010-06-01T09:05:45Z
dc.date.available2009-11-24T08:03:37Zen_ZA
dc.date.available2010-06-01T09:05:45Z
dc.date.issued2009-12en_ZA
dc.descriptionThesis (MScEng (Process Engineering))--University of Stellenbosch, 2009.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Die effek van teenpolsing op die aanvuiling van 'n 2.5-duim spiraal kruisvloei ultrafiltrasie element is eksperimenteel ondersoek. Teenpolseksperimente met 'n organiese (dekstraan) oplossing en 'n anorganiese (kaolien) suspensie is uitgevoer deur gebruik te maak van 'n polipropileenmembraan (100 000 molekulêre massa snypunt). Die konsentrasie van die dekstraanoplossing was tussen 250 en 750 mg/L en die konsentrasie van die kaolien oplossing was tussen 100 en 300 mg/L. Teenpolsing behels die aanwending van drukpolse van tussen 100 en 150 kPa aan die kant van die produk (permeaat). Die polstussenposes het gewissel tussen 1 en 15 s en die duur van die polse tussen 0.1 en 0.5 s. Die vloeitempo was tussen 500 en 1500 L/h, en die toegepaste druk was 100 kPa. Eksperimentele resultate het getoon dat terugpols effektief was vir die vermindering van membraanaanvuiling, en die verbetering van vloei deur die membraan. Met aanhoudende terugpolsing het die netto vloei toegeneem met toenemende terugpolsdruk. Daar was 'n effense toename met 'n toename in kruisvloeitempo en 'n sterk afname met toenemende voeroplossingkonsentrasie. Die beste terugpols parameters vir die twee verskillende aanvuilingsmateriale was soos volg: 0.2 s polsduur, 3 s polstussenpose en 150 kPa terugopolsdruk vir die dekstraanoplossing; en 0.2 s polsduur, 5 s polstussenpose en 150 kPa terugopolsdruk vir die kaoliensuspensie. Die beste resulate behaal vir vloei onder hierdie kondisies was 3-maal en 1.5-maal hoër as die vloei behaal sonder polsing, vir dekstraan en kaolien, onderskeidelik. Nadat die membraan aan aanvuiling, gevolg deur terugpolsing, blootgestel is, is dit skoongemaak deur skoon water met terugpolsing te gebruik. Die vloei van die skoon membrane wat voorheen met dekstraan en kaolien aangevuil is was 62% en 71% van die oorspronklike vloei, onderskeidelik. Die Taguchi metode met 'n L9 ortagonale reeks is gebruik om die belangrike terugpolsfaktore te bepaal wat 'n maksimum permeaatvloei tot gevolg gehad het. Die polsdruk het die grootste effek op die membraanvloei gehad. Polstussenpose en polsduur het 'n onbeduidende effek en die dwarsvloeitempo het 'n swak effek op membaanvloei gehad. Daar moet egter opgelet word dat hierdie waarnemings slegs van toepassing is binne die eksperimentele grense soos bepaal in die inleidende ondersoek van hierdie studie.en_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/3082
dc.language.isoenen_ZA
dc.publisherStellenbosch : University of Stellenbosch
dc.rights.holderUniversity of Stellenbosch
dc.subjectBackpulsingen_ZA
dc.subjectTaguchi approachen_ZA
dc.subjectDissertations -- Process engineeringen
dc.subjectTheses -- Process engineeringen
dc.subject.lcshMembranes (Technology)en_ZA
dc.subject.lcshFoulingen_ZA
dc.subject.lcshUltrafiltrationen_ZA
dc.titleFlux enhancement in a spiral wrap ultrafiltration element by using backpulsingen_ZA
dc.typeThesisen_ZA
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