Membrane bioreactors principle

Principles and Applications of Membrane Bioreactors in Water and Wastewater Treatment, Elsevier, Great Britain. 

Membrane bioreactors have been reviewed previously in every detail [3,4,7,8,18], There are two main types of membrane bioreactors (i) the system consists of a traditional stirred-tank reactor combined with a membrane separation unit (Figure 14.1) (ii) the membrane contains the immobilized biocatalysts such as enzymes, micro-organisms and antibodies and thus, acts as a support and a separation unit (Figure 14.2). The biocatalyst can be immobilized in or on the membrane by entrapment, gelification, physical adsorption, ionic binding, covalent binding or crosslinking [3, 7, 18]. Our attention will be primarily focused on the second case where the membrane acts as a support for biocatalyst and as a separation unit, in this study. The momentum and mass-transport process, in principle, are the same in both cases, namely when there is... 

Membrane bioreactors have been reported for the production of diltiazem chiral intermediate with a multiphase/extractive enzyme membrane reactor [15, 16]. The reaction was carried out in a two-separate phase reactor. Here, the membrane had the double role of confining the enzyme and keeping the two phases in contact while maintaining them in two different compartments. This is the case of the multiphase/ extractive membrane reactor developed on a productive scale for the production of a chiral intermediate of diltiazem ((2R,3S)-methylmethoxyphenylglycidate), a drug used in the treatment of hypertension and angina [15]. The principle is illustrated in... 

Figure 5 Operating principle of extractive membrane bioreactor technology...

S. Judd, The MBR book Principles and applications of membrane bioreactors in water and wastewater treatment, Elsevier, Oxford, 2006. 

The basic principles of bioconversion, bioreactors and biocatalysis are introduced, together with a description of the most important biocatalyst immobilization techniques. The mass transfer phenomena involved in membrane systems are discussed along with some representative configurations of membrane bioreactors, whose behaviour can be described using a simple mathematical approach. For all the aforementioned systems the most significant parameters have been defined to estimate the system performance. 

Principle of membrane bioreactors and biocatalytic membrane reactors... 

In Part I a selection of the types of membrane reactor is presented, together with chapters on the integration of membrane reactors with current industrial processes. To summarize, in Chapter 1 (Calabro) membrane bioreactors are described from an engineering point of view, together with a straightforward description and simulation, with a simple mathematical approach, of the most important configurations and processes in which they are involved. Basic principles of bioconversion, bioreactors and biocatalysis with immobilized biocatalysts are also presented. For all the cited systems the most significant parameters are defined in order to estimate their performances. The best approaches for the preparation of... 

The principle of both membrane reactors and membrane bioreactors are the same but the origin is completely different. In the case of a bioreaction enzymes or microorganisms (bacteria, fungi, mammalian ceils, yeasts) are applied under very specific reaction conditions. Both concepts wil be discussed briefiy. 

Judd, S. The MBR Book principles and applications of membrane bioreactors for water and wastewater treatment Elsevier Science Oxford, 2006, pp. 55-76. 

As is the case with pure bubble columns and gas-operated loop reactors, most bioreactors in technical use are aerated with oxygen or air. Reactors with pure surface aeration, such as roller bottles, shake flasks and small stirred reactors or special reactors with membrane aeration, are exceptions. The latter are used for the cultivation of cells and organisms which are particularly sensitive to shearing (see e. g. [28 - 29]). The influence of gas bubbles in increasing stress has been described in many publications (see e.g. [4, 27, 29, 30]). In principle it can be caused by the following processes ... 

Fig. 23.4 Organophilic pervaporation (PV) for in situ recovery of volatile flavour compounds from bioreactors. The principle of PV can be viewed as a vacuum distillation across a polymeric barrier (membrane) dividing the liquid feed phase from the gaseous permeate phase. A highly aroma enriched permeate is recovered by freezing the target compounds out of the gas stream. As a typical silicone membrane, an asymmetric poly(octylsiloxane) (POMS) membrane is exemplarily depicted. Here, the selective barrier is a thin POMS layer on a polypropylene (PP)/poly(ether imide) (PEI) support material. Several investigations of PV for the recovery of different microbially produced flavours, e.g. 2-phenylethanol [119], benzaldehyde [264], 6-pentyl-a-pyrone [239], acetone/buta-nol/ethanol [265] and citronellol/geraniol/short-chain esters [266], have been published...

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