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978-3-8439-0685-2, Reihe Technische Chemie
A contribution to design foam fractionation processes
143 Seiten, Dissertation Technische Universität Dortmund (2012), Softcover, A5
In biochemical industry foams are generally undesired because foaming is mostly accompanied by product loss and thus, effort is put into the prevention of foam formation especially during downstream processing. However, the foaming tendency caused by amphiphilic or surface-active substances in bioprocesses does not necessarily need to be disadvantageous. A downstream separation technique, where foam is actually desired and used as the separation medium, is foam fractionation. The principle of separation is the preferential adsorption of surface-active substances at a gas-liquid interface.
In this thesis, a fungal hydrolytically active enzyme, biochemically characterized as a cutinase, is separated out of the crude culture supernatant using foam fractionation. For batch and continuous foam fractionation various process parameters, like pH value or temperature, and column design parameters, such as length or diameter of the foaming column are systematically investigated in regard to separation efficiency and foam stability. For continuous foam fractionation enriching and stripping mode were examined. A recovery of 94 % and a 47-fold concentration and 19-fold purification of cutinase in the foam phase could be achieved in a single process step. This, and the lack of additives and the simple experimental procedure make foam fractionation a technique for process intensification. However, before foam fractionation can be used in industry a scale-up is necessary. Two traditional scale-up approaches were tested to enlarge the foam fractionation system. However, the investigated and enlarged foam fractionation columns were still lab-scale equipment.
Parallel to the cutinase system the industrial enzyme PLA2 was separated and purified from complete culture broth of the recombinant Aspergillus niger via foam fractionation.
As a consequence of the research presented a guideline was developed to adjust foam fractionation fast and efficiently to general enzyme systems. To validate the guideline the a pure component system, and non-foamable enzymes were investigated.