Particle separation and fractionation by microfiltration

cum laude graduation (with distinction) For the production of present-day dairy products, raw milk is often considered an entity. However, a large quality improvement could be reached if selected constituents were available. In order to achieve this, milk will have to be fractionated prior to use in dairy products. Microfiltration is an important technique for the fractionation of milk; the pore size typically being in the order of micrometers. However, due to insufficient separation caused by blockage of the filter, the potential of microfiltration is still hardly used. This instigated the Ph.D. research project of Janneke Kromkamp which aims at using microfiltration for fractionation to its fullest potential. The interaction between the different microparticles in milk and the surrounding liquid were studied at a fundamental level by means of computer simulation techniques. By coupling this information to observations on the microfiltration of milk, important new insights were obtained which can substantially improve the fractionation process. Paradoxically enough, the liquid flow was better able to fractionate particles than the membrane alone. Because the particles organise in the liquid flow, the large ones moving to the centre of the channel, the smaller ones can be separated easily. Herewith, membrane blockage, which was the biggest challenge in this thesis, is prevented. An additional advantage is that the fractionation process can be completely controlled by easily controllable process parameters. The high-quality dairy products mentioned earlier have now come within reach