Fluidized‐Bed Bioreactors

Abstract

Fluidized-bed reactors present a number of advantages that make them an attractive alternative in processes involving biocatalysts. However, fluidized-bed bioreactors are also realtively complex, basically for two reasons. First, their use requires the biocatalyst, commonly cells or enzymes, to be immobilized into or onto a solid support. Second, the hydrodynamic characterization is difficult, especially in those systems where three phases (gas-liquid-solid) are involved. The mathematical model of a fluidized-bed bioreactor needs to take into account those hydrodynamic aspects that will determine the flux model in the reactor. Moreover, the description of other aspects is also required: the mechanisms of transport between the different phases, the kinetic equations for the phenomena taking place in the biocatalytic particles, such as cell growth, product formation, substrate consumption, enzyme deactivation, and the mass balance equations in the reactor. In addition to these aspects, the application of fluidized-bed bioreactors to different kind of processes is also discussed. The potential of this type of bioreactor is also emphasized from the point of view of the different number of possible modifications in the design both of the bioreactor and the biocatalyst particles, in order to enhance its operation.

Continuous perfusion culture of encapsulated hybridoma cells

“…The microcapsule to total volume ratio is in the order of 20-25%, a typical value found in this type of bioreactors. 32 Under these conditions, gas superficial velocity in the fluidized bed was in the range 0.11×10 −2 -0.12×10 −2 m s −1 . Another relevant aspect to consider is that, due to the buffer system replacement (in order to avoid the use of bicarbonate), there was no need to feed CO 2 to adjust medium pH.…”

Biological denitrification of reverse osmosis brine concentrates: II. Fluidized bed adsorber reactor studies

“…These advantages that are extensively reviewed in literature (Sutton and Mishra 1994;Godia and Sola 1995) can be briefly summarized as follows: (i) increased process efficiency and reduced reactor sizes due to high biomass concentrations; (ii) greater operational flexibility such as approximating to plug-flow conditions or using smaller media particles for better mass transfer and heat transfer (where applicable) from liquid to solid phase; (iii) better resistance or resilience to shock loading arising from changes in influent volumetric flow rates and contaminant concentrations; (iv) lesser problems associated with reactor hydraulics, clogging, and sludge retention in the event of excessive biofilm growth; These advantages that are extensively reviewed in literature (Sutton and Mishra 1994;Godia and Sola 1995) can be briefly summarized as follows: (i) increased process efficiency and reduced reactor sizes due to high biomass concentrations; (ii) greater operational flexibility such as approximating to plug-flow conditions or using smaller media particles for better mass transfer and heat transfer (where applicable) from liquid to solid phase; (iii) better resistance or resilience to shock loading arising from changes in influent volumetric flow rates and contaminant concentrations; (iv) lesser problems associated with reactor hydraulics, clogging, and sludge retention in the event of excessive biofilm growth;…”

“…The disadvantages of fluidized-bed reactors include problems associated with biofilm control, energy consumption, reactor clogging, and start-up (Godia and Sola 1995). Reactor clogging and start-up problems arise from excessive biological growth and non-uniform fluidization, especially in anaerobic systems, where media particles undergo substantial increase in size leading to excessive bed expansion.…”

Phase Behaviour, Interactions, and Structural Studies of (Amines+Ionic Liquids) Binary Mixtures

“…The fluidized bed reactor has successfully been used as an alternative plant configuration to perform biotechnological processes addressed to the production of high added value compounds or to treat effluents 1. In general terms, such a bioreactor is characterized by the presence of microorganisms immobilized onto solid support particles submerged in a fermentation medium.…”