Ethanol is to be used as a substrate for single-cell protein production in a chemostat. The available equipment can achieve an oxygen transfer rate of 10 g O₂/l of liquid per hour. Assume the kinetics of cell growth on ethanol is of the Monod type, with µm = 0.5 h^–1, K_s = 30 mg/l, YX/S = 0.5 cells/g ethanol, and YO2/S = 2 g O2/g EtOH. We wish to operate the chemostat with an ethanol concentration in the feed of 22 g/L. We also wish to maximize the biomass productivity and minimize the loss of unused ethanol in the effluent. Determine the required dilution rate

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#Question id: 14294

#Section 5: Bioprocess Engineering and Process Biotechnology

#Question id: 14295

#Section 5: Bioprocess Engineering and Process Biotechnology

Pseudomonas methylotrophus is used to produce single-cell protein from methanol in a 1000 m³ pressure-cycle airlift fermenter. The biomass yield from substrate is 0.41 g g^{- 1}, K_S is 0.7 mg l^{- 1}, and the maximum specific growth rate is 0.44 h^{- 1}. The medium contains 4% (w/v) methanol. A substrate conversion of 98% is desirable. The reactor may be operated either in batch or continuous mode. If operated in batch, an inoculum of 0.01% (w/v) is used and the downtime between batches is 20 h. If operated continuously, a downtime of 25 d is expected per year. Neglecting maintenance requirements, compare the annual biomass production from batch and continuous reactors?

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#Question id: 14296

#Section 5: Bioprocess Engineering and Process Biotechnology

A two-stage chemostat system is used for production of secondary metabolite. The volume of each reactor is 0.5 m³; the flow rate of feed is 50 l h^{- 1}. Mycelial growth occurs in the first reactor; the second reactor is used for product synthesis. The concentration of substrate in the feed is 10 gl^-1. Kinetic and yield parameters for the organism are:

Assume that product synthesis is negligible in the first reactor and growth is negligible in the second reactor. Determine cell concentrations entering the second reactor.

#Question id: 14297

#Section 5: Bioprocess Engineering and Process Biotechnology

A two-stage chemostat system is used for production of secondary metabolite. The volume of each reactor is 0.5 m³; the flow rate of feed is 50 l h^{- 1}. Mycelial growth occurs in the first reactor; the second reactor is used for product synthesis. The concentration of substrate in the feed is 10 gl^-1. Kinetic and yield parameters for the organism are:

Assume that product synthesis is negligible in the first reactor and growth is negligible in the second reactor. Determine substrate concentrations entering the second reactor.