Bioreactors CSTR

In a batch fermentation of ethanol, kinetic data were collected as product formed. The data are shown in Table E.5.1. The data will be used to design a continuous bioreactor (CSTR) with a 1001 working volume. 

Fig. 4.1. Instrumentation control for continuous stirred tank (CSTR) bioreactor.

Fig. E.9.1. Substrate concentration versus dilution rate in a CSTR bioreactor.

The Monod rate model is valid for a CSTR bioreactor with maximum specific growth rate of 0.5 li 1 and K, 2 g-1. What would be a suitable dilution rate at steady-state condition, where there is no cell death if initial substrate concentration is 50g-l-1 and yield of biomass on substrate is 100%. 

A special CSTR fermentation known as a chemostat bioreactor is used for microbial cell growth. The rate of biomass generation is given by ... 

We wish to compare the performance of two reactor types plug flow versus CSTR with a substrate concentration of Csf = 60g-m 3 and a biomass yield of Y = 0.1. In a plug flow bioreactor with volume of 1 m3 and volumetric flow rate of 2.5 m -li what would be the recycle ratio for maximum qx compared with corresponding results and rate models proposed for the chemostat ... 

A tubular bioreactor design with operational may lead to a CSTR, having sufficient recycle ratio for plug flow that behave like chemostat. The recirculation plug flow reactor is better than a chemostat, with maximum productivity at C, 3 g-m 3. Combination of plug flow with CSTR which behave like chemostat was obtained from the illustration minimised curve with maximum rate at CSf = 3 g-m-3. 

In regard dynamics and control scopes, the contributions address analysis of open and closed-loop systems, fault detection and the dynamical behavior of controlled processes. Concerning control design, the contributors have exploited fuzzy and neuro-fuzzy techniques for control design and fault detection. Moreover, robust approaches to dynamical output feedback from geometric control are also included. In addition, the contributors have also enclosed results concerning the dynamics of controlled processes, such as the study of homoclinic orbits in controlled CSTR and the experimental evidence of how feedback interconnection in a recycling bioreactor can induce unpredictable (possibly chaotic) oscillations. 

Figure 11.9 Different arrangements and modes of operation for membrane bioreactors Continuous Stirred Tank Reactor (CSTR) with recirculation arrangement (a), dead-end cell (b), tubular with entrapped enzyme (c).

The bioreactor has been introduced in general terms in the previous section. In this section the basic bioreactor concepts, i.e., the batch, the fed-batch, the continuous-flow stirred-tank reactor (CSTR), the cascade of CSTRs and the plug-flow reactor, will be described. 

When the biochemical reactors are kinetically controlled, the batch bioreactors and the PFR are described by the same design equations (Equations (11.25) and (11.28)) and show a better performance than the CSTR in most cases, except for substrate inhibition kinetics. 

Similar behavior to that of the nonisothermal CSTR system will be observed in an isothermal bioreactor with nonmonotonic enzyme reaction, called a continuous stirred tank enzyme reactor (Enzyme CSTR). Figure 3.27 gives a diagram. 

This case study presents the design of a biochemical process for NO removal from flue gases, where an absorber and a bioreactor are the main units. Based on a rough estimation of Hatta numbers, it was concluded that a spray tower offering a large G/L interfacial and a small liquid fraction is the best type of equipment, favoring the main chemical reaction. The bioreactor was chosen as a CSTR. 

Figure 10.2.1 Plug flow reactor simulation using NSTAGEs of CSTRs for solution. [From Analysis of a Continuous, Aerobic Fixed-Film Bioreactor. I.. Stcady-.Siaio Bclia ior. by Y. Park.. VI. F. Davis and D. -. Wallis, Biotech. 26 11984) 457. copyright...

In this section we return to mass equations on the cells [Equation (7-117)] and substrate [Equation (7-118)] and considerthe case where the vol-CSTR umetric flow rates in and out are the same and that no live (i.e., viable) cells enter the chemostat. We next define a parameter common to bioreactors called the dilution rate, D. The dilution rate is... 

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. 

Eq. 5.24 represents the model of steady-state operation of CSTR. As in the case of CPBR, it allows the determination of the steady-state X for any given combination of Mcat/F and can also be used for bioreactor design, since bioreactor dimensions will be determined from the concentration of biocatalyst that can be adequately handled in the bioreactor ... 

Once kii has been determined, the curve of reactor operation (X vs t) can be obtained from Eqs. 5.73 or 5.74. Values of Xi are obtained from Eqs. 5.16 or 5.24 for a certain enzyme load and feed flow-rate in the bioreactor. Eqs. 5.73 and 5.74 also allow bioreactor design (volume determination). In the case of CPBR, the volume of the catalytic bed can be directly determined from the amount of biocatalyst required, by dividing its mass by the apparent density of the biocatalyst bed, which is easily determined. In the case of CSTR, the volume of reaction can also be determined from the amount of biocatalyst required, by dividing its mass by the biocatalyst concentration, which is usually determined by hydrodynamic considerations. 

A bioreactor is a reactor that utilizes either a living organism or one or more enzymes from a living organism to accomplish a certain chemical transformation. Bioreactors can be either CSTRs (in which case they are known as chemostats) or PFRs. 

Certain characteristics of a bioreactor must be more tightly controlled than they must be in a normal CSTR or PFR because cellular enzymes are very complex and have relatively narrow ranges of optimum activity. These include, but are not limited to ... 

In principle the use of a well-stirred bioreactor in a continuous flow mode offers significant advantages over operation in a batch or semibatch mode, but the majority of bioreactors in industrial use are operated in the latter modes. However, the actual performance of single CSTR or a cascade of such reactors often fails to meet the expectations... 

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