A fermentation system has a KLa of 3 s-1 and a C0* of 5 ppm of O2. If the bulk liquid is completely depleted of oxygen, then the oxygen transfer rate will be equal to
Options
A. zero
B. 15 mg.l-1.s-1
C. 10 mg.l-1.s-1
D. 5 mg.l-1.s-1
Correct Answer
15 mg.l-1.s-1
Agitation and Aeration problems
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1. During fermentation, the saturation concentration of oxygen was reduced from 7 ppm. to 1 ppm. Which one of the following conclusions can be drawn?
Options
A. Microbial growth is oxygen limited since the oxygen concentration is lesser than the saturation concentration
B. Microbial growth is not oxygen limited since the oxygen concentration is lesser than the saturation concentration
2. For aerated mixing vessels in an aqueous solution, the mass transfer coefficient (kL) co-relating power consumption (Pm) and fermenter volume (V) can be expressed as
Correct Answer: Off-centre impellers should only be used with reactors with volumes less than 10 m3
5. A cylindrical reactor fitted with Rushton Turbine has a liquid volume of 100,000 litres. It has an aspect ratio (the ratio of the channel height to the width) of 2:1. The diameter of the impeller should be approximately:
Correct Answer: they provide high shear mixing conditions
8. A fermentation system has a KLa of 3 s-1 and a C0* of 5 ppm of O2. If the bulk liquid is saturated with oxygen then the oxygen transfer rate will be equal to