Membrane bioreactor application examples

A number of pervaporation membrane bioreactor (PVMBR) applications have also been reported [3.3]. These represent a special class of membrane bioreactor applications, which are discussed more extensively in Chapter 4. A number of studies utilizing PVMBR involve esterification reactions. Van der Padt et al. [3.46], for example, studied in a PVMBR the synthesis of triglycerides from glycerol and fatty acids. The reaction is equilibrium limited, and is described as follows ... 

In the following, a number of integrated reaction-separation systems wiU be discussed, with emphasis on the application of polymeric membranes. As a result, the systems discussed will be Hmited to relatively low temperatures, typically below 120°C. In Section 13.2, appHcations of membranes in chemical synthesis will be described. Subsequently, in Section 13.3 various examples of membrane bioreactors will be discussed. 

The BOHLM systems, integrating reaction, separation, and concentration functions in one apparatus (bioreactor), attracted great interest in the last few years. Bioreactors combine the use of specific biocatalyst for the desired chemical reactions, with repeated or continuous application of it under very specific conditions. Such techniques were termed hybrid membrane reactors. In biotechnology and pharmacology, these applications are termed hybrid membrane bioreactors or simply bioreactors (see Table 5.13). An example of an experimental setup of the bioreactor system is shown sche-maticaUy in Figs 5.14 and 5.15. 

Pervaporation membrane reactors (PVMR) are an emerging area of membrane-based reactive separations. An excellent review paper of the broader area of pervaporation-based, hybrid processes has been published recently [3.1]. The brief discussion here is an extract of the more comprehensive discussions presented in that paper, as well as in an earlier paper by Zhu et al [3.2]. Mostly non-biological applications are discussed in this chapter. Some pervaporation membrane bioreactor (PVMBR) applications are also discussed additional information on the topic can be found in a recent publication [3.3], and a number of other examples are also discussed in Chapter 4. 

Lipases used in laundry detergents and in other bulk applications do not require enzyme immobilization however, an increasing number of applications in synthesis and biotransformation demand an immobilized biocatalyst for efficient use. It has been claimed that the success of a lipase catalyzed biotransformation for the production of certain pharmaceuticals depends on immobilization. For example, in the industrial preparation of the chiral intermediate used in the synthesis of Diltiazem, the lipase from Serratia marcescens was supported in a spongy matrix, which was used in a two-phase membrane bioreactor (Cowan 1996). 

Abstract In this chapter, membrane bioreactors are described from an economic point of view. Economic analysis is a crucial stage in plant design, project and control and also requires an evaluation of the research, development and commercialization of the products and bioproducts. Such an analysis is focused here on membrane bioreactors and reactors, also taking into account the separation units such as micro-, ultra- and nano-flltration units that might be used as a downstream process or as pretreatment steps. The most important rules and parameters are first introduced. Some examples of application and case studies are also reported. 

Efficient stem cell expansion is a key bottleneck for clinical application and commercialization of stem cell therapy. Membrane bioreactors may make a significant contribution due to its important features such as possibility for uniform chemical and biochemical conditions within the bioreactor, low or even zero hydrodynamic shears, large surface-to-volume ratios, and physical separation between two cell types but allowing biochemical signaling between them. For example, it may be possible to culture the feeder cells on one side of the membrane, while culturing human embryonic stem cells on the other. In this way human embryonic stem cells are not mixed with the feeder cells, which eliminates the need for later difficult separation, but get the biochemical signals from the feeder cells that are necessary to proliferate embryonic stem cells (e.g., Choo et al., 2006 Klimanskaya et al., 2005). 

An early example of a patent on membrane contactor for gas transfer is in Ref. [12]. Harvesting of oxygen dissolved in water and discharging of CO2 to the water is presented in Ref. [13]. A membrane device to separate gas bubbles from infusion fluids such as human-body fluids is claimed in Ref. [14]. A hollow fiber membrane device for removal of gas bubbles that dissolve gasses from fluids delivered into a patient during medical procedures is disclosed in Ref. [15]. Membrane contactors have also found application in dissolved gas control in bioreactors discussed in Refs. [16-17]. 

MIP membrane adsorbers for the specific sample enrichment from large volumes by membrane SPE, and for the specific decontamination of large process streams will be among first examples for applications (cf Section V.D). Other promising continous separations are the resolution of enantiomers or the product removal from bioreactors, both feasible by electrodialysis or dialysis (cf. Section V.B). 

Chapter 19 deals with the physicochemical aspects of the most ubiquitous interface in living systems, the biological membrane. We conclude with Chapter 20, which deals with bioadhesion, that is, the accumulation of biological cells at interfaces. Bioadhesion may lead to adverse effects—for example, fouling of surfaces—but in other applications it is desired—for example, immobilization of cells in bioreactors. 

The use of various membrane configurations coupled with bioreactors has lead to multiple functionality improvements and innovations. Implementation as guard beds, recycle conditioning vessels (with solids separations capabilities), in situ extraction systems, and slipstream (and bypass) reactors for biocatalyst activity maintenance, are but a few important examples representing successful applications when using living systems operating in controlled microenvironments. 

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