Bioreactors washout

The bioreactor has two equilibrium points within the physically realizable domain. Such equilibrium points correspond to washout and operation conditions. For the operation condition (i.e., when degradation of the organic... 

Two fundamentally different types of bioreactor setups can be distinguished. In the first type of reactors, MTBE-degradation occurs by bacteria in suspension in continuously stirred tank reactors (CSTR) (Table 6). An obvious advantage of this setup is the optimal mixing of MTBE-degrading biomass, contaminants and oxygen, reducing transport Hmitations to a minimum. However, specialized adaptations are required to prevent washout of biomass from the reactor. Three different methods exist. 

BWM burster washout machine ICB immobilized-cell bioreactor... 

Since substrate costs generally make up about 50 % of production costs substrate conversion is a key parameter for the economy of bioreactions. The lower the intensity of longitudinal medium dispersion, the higher the substrate conversion in continuous bioreactors under corresponding operational conditions. However, at a low dispersion intensity, cell washout occurs. To avoid washout and to achieve high substrate conversion,tower reactors with optimum longitudinal dispersion or tower loop reactors with an optimum recycling rate can be used (1). ... 

The steady-state values of this model as a function of D are shown in Fig. 6.6. Note that the biomass concentration does not vanish above the washout point (see also Sinclair and Brown, 1970 Toda and Dunn, 1982). Imperfectly mixed bioreactor systems have been summarized recently by A. Moser (1985b). 

Spinfilters and sedimentation devices do not retain all cells within a bioreactor and some washout occurs. Total retention of biomass is feasible by using an external microfilter to continuously harvest a cell-free stream, as shown in Fig. 28. The cells are returned to the bioreactor. The bioreactor operational schemes identified here are the ones most commonly used other variations on these schemes are encountered occasionally. 

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