Outlet substrate concentration

Inlet and outlet substrate concentrations Biofilm erosion rate... 

Thus, the specific growth rate in a chemostat is controlled by the feed flow rate, since // is equal to D at steady state conditions. Since ft, the specific growth rate, is a function of the substrate concentration, and since fi is also determined by dilution rate, then the flow rate F also determines the outlet substrate concentration S. The last equation is, of course, simply a statement that the quantity of cells produced is proportional to the quantity of substrate consumed, as related by the yield factor Yx/s-... 

Assuming maximum reaction rates, choose a value of F and S1F, and estimate the outlet substrate concentration at steady state. What oxygen supply rate would be required Verify by simulation. 

You carried out an enzymatic reaction in a 5-L CSTR. The inlet substrate concentration was 100 mmol/L and the flow rate was set 1 L/hr. After a steady-state was reached, the outlet substrate concentration was 10 mmol/L. 

CSBR). In this case the bioconversion is run under approximately steady-state conditions where the position of reaction equilibrium lies toward the products of the conversion. In this case the concentration of product (proportional to Sj — S0 ) at a given reactor residence time becomes a function of both the flow rate (Q) into the reactor and reactor volume, in addition to the factors discussed above for batch mode reactors (i.e., catalyst parameters and density, inlet substrate concentration S and outlet substrate concentration S0). 

B.I. We wish to use the enzyme whose kinetics, described 1 (5.51), were studied earlier in this chapter, in an immobilized-enzyme packed bed reactor. Neglecting any internal mass transfer resistance (we assume the enzyme is immobilized in very small pellets), we compute the outlet substrate concentration by solving the ODE-IVP... 

The average biomass concentration is defined as the product of yield of biomass and change of substrate concentrations in inlet and outlet streams. The biomass balance is ... 

As indicated below in Fig. 3.21, feed enters the reactor at a volumetric flow rate F0, with cell concentration X0 and substrate concentration S0. The vessel contents, which are well-mixed, are defined by volume V, substrate concentration S and cell concentration X. These concentrations are identical to those of the outlet stream, which has a volumetric flow rate F. ... 

A strain of yeast is being cultivated in a 30-L CSTF with a cell recycling system (cell settler) as shown in the following figure. The cell settler was designed so that the cell concentration of its outlet stream is 30 percent of that of its inlet stream, whereas the substrate concentrations of the two streams are the same. The growth rate of the cells can be represented by the Monod kinetics with the parameters Ks = 0.05 g/L, max = 0.3 h-1, and YX/s = 0.025. Calculate the steady-state substrate and cell concentrations in the fermenter. The inlet substrate concentration is 100 g/L and the flow rate is 20 L/hr. The feed stream is sterile. 

Fig. 29. Origin of systematic errors in spite of potentially error-free analysis. On-line sampling setups (top) and time trajectories of limiting substrate concentration during sample preparation in the two paradigmatic setups depending on the actual culture density (bottom). Either a filter in bypass loop is used for the preparation of cell-free supernatant (upper part in top insert) or an aliquot of the entire culture is removed using an automatic sampler valve and a sample bus for further inactivation and transport of the samples taken (lower part). Both methods require some finite time for sample transportation from the reactor outlet (at z = 0) to the location where separation of cells from supernatant or inactivation by adding appropriate inactivators (at z = L) takes place. During transport from z = 0 to z = L, the cells do not stop consuming substrate. A low substrate concentration in the reactor (namely s KS) and a maximal specific substrate consumption rate of 3 g g h 1 were assumed in the simulation example to reflect the situation of either a fed-batch or a continuous culture of an industrially relevant organism such as yeast. The actual culture density (in g 1 1) marks some trajectories in the mesh plot. Note that the time scale is in seconds...

When a CSTB (volume V) is operated with a constant inlet and an outlet flow rate (F) with the cell concentration of Cj, and substrate concentration, the material balance for the microorganisms in a CSTB can be written as... 

Assume that you obtained the Cg versus t curve you calculated in part (a) experimentally. Estimate K/ and by plotting the (Cg - Cs)/ln(Cg /Cg) versus f/ln(Cgj,/Cg) curve according to Eq. (2.38). Is tnis approach reliable Chemostat (continuously stirred-tank reactor) runs with various flow rates were carried out. If the inlet substrate concentration is 300 mol/m and the flow rate is 100 cm / min, what is the steady-state substrate concentration of the outlet The reactor volume is 300 cm. Assume that the enzyme concentration in the reactor is constant so that the same kinetic parameters can be used. 

Continuous mode of operation in well-mixed stirred tanks often starts as a fed-batch process at constant feed rate under a given substrate concentration Cjo, so that D = fi until an outlet valve is opened. This is performed in order to allow the effluent to be continuously recovered from the reactor at an outlet flow rate equal to the inlet flow so that the volume of the medium in the fermenter stays constant and steady state is achieved. 

Now substitute the outlet concentration of substrate, resulting in the following equation ... 

Typical results for the outlet concentration of substrate and product are shown in Figure 2.57 for two different values of tf/tp. When tf/tp = 0.9, for most of a cycle the... 

Figure 2.57 Substrate (dashed line) and product (full line) concentrations at the channel outlet for two different operation modes, taken from Stepanek etal. [169. ...

Change the feed concentration of substrate. Does this alter the steady state value of S in the reactor outlet Why ... 

---