Microfiltration cell-liquid separation

After extraction, the enzyme preparation is contaminated with undisrupted cells and cell debris that have to be removed before purification. Common operations of solid-liquid separation, like centrifugation and dead-end filtration, can be used but the drawbacks already mentioned with respect to cell separation are augmented by the very small size of the cell fragments. Microfiltration is a better option that has been used successfully (Vaks et al. 1984 Chan et al. 1991). 

Pharmaceutical Removal of suspended matter is a frequent application for MF. Processes may be either clarification, in which the main product is a clarified liquid, or solids recovery. Separating cells or their fragments from broth is the most common application. Clarification of the broth in preparation for product recovery is the usual objective, but the primary goal may be recovery of cells. Cross-flow microfiltration competes w l with centrifugation, conventional filtration by rotary vacuum filter or filter press and decantation. MF delivers a cleaner permeate, an uncontaminated, concentrated cell product... 

Consider a typical antibiotic production process, as illustrated in Figure 11.1.1. The antibiotic is present in a fermentation broth as a very dilute solution in the presence of considerable soluble impurities, as well as a significant concentration of whole cells and cellular debris. The particulate materials, such as whole cells, cell debris, etc., are removed first by filtration or centrifugation. The filtration method is described under rotary vacuum filtration (Section 7.2.1.5) or microfiltration (Section 7.2.1.4) of the tangential-flow type (TFF). Centrifugation is illustrated in Sections 7.3.2.1 and 7.S.2.2 via different types of centrifuges. This step has heen characterized as removal of insolubles (Belter et al, 1988) - it is essentially separation of cellular particles from a liquid solution of the product. 

This chapter, in addition to surveying membrane types and production, overviews applications of gas and liquid membrane separation and polymer films as banier layers. Water purification for reuse and in desalination using reverse osmosis and nano-, ultra-, and microfiltration are discussed. Electrodialysis, dialysis, and hemodialysis are also covered. Membranes in emerging technologies are described including fuel cell membranes, membranes in lithium batteries, conducting polymer membranes, and thin film membranes used in LED and photovoltaic applications. 

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