Multiphase reactors bioreactors

Robert Langer, Polymer Systems for Controlled Release of Macromolecules, Immobilized Enzyme Medical Bioreactors, and Tissue Engineering J. J. Linderman, P. A. Mahama, K. E. Forsten, and D. A. Lauffenburger, Diffusion and Probability in Receptor Binding and Signaling Rakesh K. Jain, Transport Phenomena in Tumors R. Krishna, A Systems Approach to Multiphase Reactor Selection... 

Bioreactors In biotechnology, although single-phase reactors are used (e.g., see the enzyme reactor described above), multiphase reactors are predominant. There are characteristics of bioreactors that set them apart from the t) ical chemical reactors, such as, for example, the presence of biomass that can remain in suspension but can also form biofilms on any surface. Formation of biofilms can either be a desired or an unwanted side reaction, depending on the objective of the application. 

For measurement by electrochemical methods, probes have to be developed. For example, knowledge of the magnitude of the frictional forces between the solids and the gas-liquid mixture is very important for design of bioreactors. The growth of biomass on solid surfaces may be sensitive to shear stress. In fluidized bed bioreactors the suspended carriers are used for microbial immobilization or enzyme encapsulation. The knowledge of shear stress is important because some micro-organisms and cells attached to microcarriers are sensitive to excessive friction. The aim is to develop and verify a fast and inexpensive method for measuring the frictional forces in multiphase reactors beds. 

G. J. Eye, J. M. Woodley, (Advances in the selection and design of two liquid phase biocatalytic reactors), in Multiphase Bioreactor Design, J. M. S. Cabral, M. Mota, J. Tramper (eds.), Taylor Francis, Fondon, pp. 115-134, 2001. 

Melo, L.F. and Oliveira, R. (2001) Biofilm reactors, in Multiphase Bioreactor Design (eds J.M.S. Cabral, M. Mota and J. Tramper), Taylor and Francis, pp. 271-308, London. 

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... 

Additional information on mechanically agitated gas-liquid-solid reactors can be obtained in van t Riet and Tramper (Basic Bioreactor Design, Marcel Dekker, 1991), Ramachandran and Chaudhari (Three-Phase Catalytic Reactors, Gordon and Breach, 1983), and Gianetto and Silveston (Multiphase Chemical Reactors, Hemisphere, 1986). Examples... 

Prazeres DMF, Cabral JMS (2001) Enzymatic membrane reactors. In Cabral JMS, Mota M, Tramper J (eds) Multiphase bioreactor design. Taylor Francis, London... 

Membrane reactors were classically grouped according to the hydrodynam-ics/configuration of the system in CSTR and PFR types [106]. However, this proved vmable to comprise some commonly used types in UF, such as flat membranes or dead-end operated modules and multiphase bioreactors. A classification based on the contact mechanisms that bring together substrate and biocatalyst was thus proposed [110]. Thus, membrane reactors could be divided into direct contact, diffusion contact, and interfacial contact reactors. 

Solid particle size in stirred tank reactos, loop reactors and bubble columns is usually in the range of 100 - 200 and solid concentration is rather low whereas in multiphase fluidized beds the solid concentration as well as solid particle size is larger. The density difference of liquid and solid usually is large, except in bioreactors, where one is faced also with agglomeration problems and nonnewtonian behavior of the suspension. 

ANSYS simulation enables engineers to study multiphase distribution, heat and mass transfer calculations, chemical kinetics and reaction of gas-liquid reactions. These include the design of plate columns, packed columns and bubble columns, a loop reactor and bioreactor development, gas-in-liquid dispersion studies and emulsion design. 

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