Adsorption mechanisms of milk components on synthetic membrane filter surfaces
This is an ear-marked 4 year project offered through the CDT in Sustainable Chemical Technologies – a centre operated jointly by Chemical Engineering & Chemistry at the University of Bath. Students spend their first year pursuing 2 x 6 month short research projects, and extensive skills training. Subsequently, a 3 year PhD project is undertaken.
Supported by Tetra Pak Processing Systems (Lund, Sweden)
Fouling of milk components upon membrane surfaces is an area that has been investigated at Bath for over twenty years. Consequently, all of the necessary experiment and computational facilities required are already in place.
The Membrane Applications Laboratory has recently developed the concept of ‘beneficial fouling’ i.e. the functionalisation of surfaces with elements of the food stream being treated, to give favourable separation and flux characteristics. Recent patents and papers in this area have extended this concept to generate ‘easy clean’ as well as low fouling surfaces using food adsorption to surfaces. Functionalising existing, commercially available membranes to be low foul / easy clean is conceptually a complimentary but very different prospect to laboratory synthesis of membranes that are inherently anti-foul – an approach taken by the majority of the academic membrane research community. An important aim of the research is to increase our understanding of fouling by milk components, both in fresh and fermented milk, on microfiltration and ultrafiltration membrane surfaces following surface functionalisation. Modification of the milk feeds by thermal pre-treatments is also of great commercial interest, and will be investigated.
Milk component fouling of membrane filters is complex – calcium phosphate displays an inverse solubility with temperature, and forms a tenacious and abundant foulant. Thermal treatment of milk products in the pasteurisation temperature / time profile also leads to two important phenomena related to proteins: denaturation and aggregation-lactoglobulin and -lactalbumin are principally responsible for controlling the morphology and structure of the protein deposits. Thermally denatured proteins can aggregate in either bulk or surface controlled processes. On non-heated membrane surfaces the expectation would be that thermally affected protein / phosphate species would migrate from the bulk onto and into the porous structure. As with all membrane filters, the hydrophobicity, roughness and charge of the membrane will all affect its subsequent filtration properties, and will be investigated fully.
A key aim of the project will thus be to determine how the composition and thermal processing history of milk based feeds affects the subsequent filtration performance with respect to the location, structure and extent of the fouling deposits.
Milk processing and cleaning operations consume large quantities of water, and generate effluent of an alkali nature with a high BOD; these streams must be treated, and cause a particular problem when they combine with domestic effluent streams in sewage works. By understanding the adhesion and removal mechanisms on functionalised surfaces, this project will seek in minimise the amount of water consumed, and the effluent generated. There is thus a strong sustainability focus in the outputs from this project.
Tetra Pak are experts in milk processing and packaging. They will supply industrial support and guidance in terms of the selection of appropriate milk based feeds, and industrially relevant thermal processing conditions. Tetra Pak also have extensive pilot plant facilities that will be available for use in the project. This will be particularly valuable when determining the applicability of membrane surface treatments, feed modifications or cleaning protocols to industrial scale operations.
The work will be novel, industrially relevant, internationally supported, and with high impact. It will be very publishable.
The Centre for Doctoral Training (CDT) in Sustainable Chemical Technologies at the University of Bath.
The project is offered in collaboration with Tetra Pak Processing Systems, Lund, Sweden.
1st class degree in Chemical Engineering. Funding restrictions mean that applications can only be considered from UK citizens. Please do not apply unless you meet the selection criteria.
This CDT studentship offers a stipend (at the usual research council rate) plus all university fees paid. In addition, the CDT offers £3K per year towards project consumable costs. An additional fund may be applied for to cover the cost of periods spent overseas to visit sponsors, or present at conferences.
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FTE Category A staff submitted: 61.00
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