Filtration microfiltration

Filtration Cross-flow filtration (microfiltration includes cross-flow filtration as one mode of operation in Membrane Separation Processes which appears earlier in this section) relies on the retention of particles by a membrane. The driving force for separation is pressure across a semipermeable membrane, while a tangential flow of the feed stream parallel to the membrane surface inhibits solids settling on and within the membrane matrix (Datar and Rosen, loc. cit.). 

Separation or clarification techniques, grit separation, sedimentation, air flotation, filtration, microfiltration and ultrafiltration, and oil-water separation. 

Nanofiltration Filtration for the treatment of water that removes suspended particles that are larger than about 0.001 pm (compare with Donnan exclusion, filtration, microfiltration, reverse osmosis, and ultrafiltration). 

Reverse osmosis The use of pressure to force the solvent of a solution through a membrane, but not its solutes (compare with filtration, microfiltration, nanofiltration, and ultrafiltration). 

Industrial products are mostly of the extracellular variety. They can be recovered directly from the fermentation broth. The primary recovery involves removing the cells from the broth, aptly called cell separation. Three different techniques are commonly used to achieve this goal filtration, microfiltration, and centrifugation. 

The most common sort of embodiment involving a liquid phase is the membrane separation of suspended solids from liquids, denoted variously by the terms filtration, microfiltration, and ultrafiltration, depending on the particle size, and which may include colloidal suspensions and emulsions. The solid particulates, for the most part, are deposited in the interstices or pores of a membrane barrier, and accordingly will require an intermittent backflushing operation. 

Depending on the size of cells and debris, and the desired clarity of the filtrate, microfiltration membranes with pore sizes ranging from 0.01 to 10 pm can be used. In cross-flow filtration (CFF see Figure 9.2b), the liquid flows parallel to the membrane surface, and so provides a higher filtration flux than does dead-end filtration (Figure 9.2a), where the liquid path is solely through the membrane. In CFF, a lesser amount of the retained species will accumulate on the membrane surface, as some of retained species is swept from the membrane surface by the... 

Physical Techniques Physical techniques include ultraviolet radiation (UV), membrane filtration [microfiltration (MF) and ultrafiltration (UF)j, and sand filtration. These techniques either modify the bacterium itself to hinder reproduction (UV) or remove bacteria via particle size filtration (MF, UF, and sand filtration). These techniques can be capital intensive and do little to address biofilm once formed. 

Fig. 33.2 Membrane separation processes are divided into conventional filtration, microfiltration, ultrafiltration, reverse osmosis, gas separation, and pervaporation according to the pore sizes of the membranes. The sizes of selected molecules ranging from water (2.7 A in diameter) to starch (10 A) are given for comparison. (Modified from Ref. 36.)...

Consider first the case of constant filtration flux in cake filtration/microfiltration. Since the volume flux Vs is... 

Figure 6.3.25. Steady state filtration/microfiltration of a slurry via bulk flow perpendicular to the force direction, (a) Bulk motion of fiiter/membrane containing the cake perpendicular to the force direction, (b) Bulk motion of the suspension/slurry perpendicular to the force direction.

Filtration, microfiltration The removal of particles of 0.1 to 10 microns in size. 

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