A fermentation process involving a single stage chemostat is used to produce the amino acid lysine. The same process has been modified to include cell recycle, with a recycle ratio of 0.3 and a cell concentration factor of 2.5. Assuming that all other conditions are identical, how much will cell concentration change due to the use of cell recycle?

Problem 2.

A two-stage fermentation process is being used to grow fungal cells. The feed stream is at a flowrate of 50 L/min and contains 220 g/l Glucose (which is the limiting nutrient). The volume of the first fermenter is 400 L. The steady state cell concentration in fermenter 1 is 110 g/l, and the steady state cell concentration in fermenter 2 is 140 g/l. Other known fermentation parameters are Y_x/s=0.65, µ₂=0.04 min^-1.

Determine the following: a) µ₁, b) Volume of fermenter 2, c) Steady-state substrate concentrations in fermenter 1 and fermenter 2.

Problem 3.

A fermentation process is being used to produce yeast cells. Using the following conditions, determine Productivity for both batch and continuous fermentation processes at growth rates of µ = 0.05, 0.1, 0.2, 0.4, 0.8, and 1 hr^-1. Assume that the continuous system is a standard single stage continuous reactor with no recycle. X_o = 2.0 g/l, X_f =3.5 g/l Total batch turnaround time, t = 1.5 hrs (includes lag, delay, and turnaround times).

Make a graph of Productivity vs Growth Rate comparing both systems.

What conclusions can be made regarding productivity in batch and continuous systems as a function of growth rate?