Microfiltration membrane fouling by dairy proteins : thesis submitted for the degree of Doctor of Philosophy at Massey University, New Zealand

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dc.contributor.authorMarshall, Allen D.
dc.date.accessioned2012-01-25T01:35:21Z
dc.date.available2012-01-25T01:35:21Z
dc.date.issued1994
dc.descriptionEmbargoed until 13 September 1996en_US
dc.description.abstractMicrofiltration membrane fouling occurs through the deposition of proteins both on the membrane surface and within the membrane pores. Fouling is complex with both the nature and location of fouling dependent upon the properties of the feed material, the properties of the membrane material and the operating conditions used. Two aspects of fouling have been investigated, one in which the feed contained proteins considerably larger than the membrane pores (casein micelles) and the other, in which the protein (β-lactoglobulin) was much smaller than the pores. In this way, it was possible to separately investigate surface layer formation and fouling within the membrane pores. It has been demonstrated that a casein "gel layer" forms on the membrane surface causing severe fouling during the microfiltration of skim milk on a 0.1 μm polysulphone membrane if the combination of cross-flow velocity and permeate flux leads to a concentration of casein at the membrane wall equal to or higher than that required for "gel layer" formation. Once formed, the gel layer restricts the passage of protein through the membrane and reduces plant throughput. During the microfiltration of β-lactoglobulin on a 0.1 μm zirconium oxide membrane, in the presence of calcium and with high fluxes, protein-protein interactions at or near the pore entrance lead to pore narrowing and the eventual retention of protein by the membrane. High localised shear rates at the pore entrance lead to partial unfolding of the protein and calcium appears to form an ion-bridge between exposed negatively charged protein groups leading to aggregation and multi-layer deposition on the membrane pore walls. The removal of calcium or a reduction in the permeate flux prevents severe fouling and greater than 90% transmission of protein can be achieved. The importance of understanding the properties of the feed material in interpreting and explaining membrane fouling is stressed.en_US
dc.identifier.urihttp://hdl.handle.net/10179/3019
dc.language.isoenen_US
dc.publisherMassey Universityen_US
dc.rightsThe Authoren_US
dc.subjectMembrane filtersen_US
dc.subjectFoulingen_US
dc.subjectMembrane separationen_US
dc.subjectMilk proteinsen_US
dc.titleMicrofiltration membrane fouling by dairy proteins : thesis submitted for the degree of Doctor of Philosophy at Massey University, New Zealanden_US
dc.typeThesisen_US
massey.contributor.authorMarshall, Allen D.
thesis.degree.disciplineFood Technology
thesis.degree.grantorMassey University
thesis.degree.levelDoctoral
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophy (Ph.D.)
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