Bioprocessing dialysis

Figure 2.5 Possible technological solutions to bioprocess problems a) Fed-batch culture b) Continuous product removal (eg dialysis, vacuum fermentation, solvent extraction, ion exchange etc) c) Two-phase system combined with extractive fermentation (liquid-impelled loop reactor) d) Continuous culture, internal multi-stage reactor e) Continuous culture, dual-stream multi-stage reactor f) Continuous culture with biomass feedback (cell recycling). (See text for further details).

In bioprocesses, a variety of apparatus that incorporate artificial (usually polymeric) membranes are often used for both separations and bioreactions. In this chapter, we shall briefly review the general principles of several membrane processes, namely, dialysis, ultrafiltration (UF), microfiltration (MF), and reverse osmosis (RO). 

Only articles that raise the productivity of a bioprocess by removing the product selectively are included. Therefore, processes that improve their productivity by the implementation of a simple cell recycle or another immobilization system are not taken into account. Nor is dialysis, which is mainly used as a biomass retention system or sometimes as a means of removing unwanted by-products. Information about dialysis cultures is available in the review by Portner and MSrkl [32]. 

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