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- Question
The main function(s) of a draft tube in an air lift fermenter is/are to
Options- A. increase the solubility of oxygen
- B. distribute shear forces throughout the reactor and minimise bubble coalescence
- C. concentrate shear forces around the sparger
- D. concentrate shear forces near the disengagement zone
- Correct Answer
- distribute shear forces throughout the reactor and minimise bubble coalescence
- 1. In an airlift bioreactor, the spent gases released from the liquid are called
Options- A. downcomer
- B. disengagement zone
- C. air riser
- D. flotsam Discuss
- 2. Axial flow impellers
Options- A. provide high shear conditions for breaking up bubbles
- B. provide low shear conditions and are suited for use in shear sensitive procesess
- C. provide direct flow towards the walls of the reactor
- D. none of the above Discuss
- 3. The production of an amylase from starch by Aspergillus niger is often performed in a fed batch fermenter. This is due to the reason that
Options- A. fed-batch reactor can be used to minimize starch concentrations and prevent a. niger from fermenting
- B. fed-batch reactor can be used to minimize starch concentrations and thus reduce the viscosity of the medium
- C. continuous reactor can be used to minimize starch concentrations and their inhibitory effects
- D. all of the above Discuss
- 4. Unsteady state mass balance for dynamic model of continuous stirred tank reactor (CSTR) is
Options- A. time rate of total amount in rector = rate of addition to reactor -rate of removal + rate of formation
- B. total amount in rector = rate of addition to reactor - rate of removal + rate of formation
- C. rate of total amount in rector = rate of addition to reactor - rate of removal + rate of formation
- D. none of the above Discuss
- 5. A continuous reactor has a dilution rate of 0.5 h-1. Its residence time would be
Options- A. ln(2)/0.5
- B. ln(2) x 0.5
- C. 0.5 h
- D. 2 h Discuss
- 6. Which of the following model holds correct for the two-film theory? (where KL is the mass transfer coefficient, DAB diffusivity and Zf film thickness)
Options- A. KL = DAB/Zf
- B. KL = DAB
- C. KL = Zf/DAB
- D. KL = DAB.Zf Discuss
- 7. A culture system with constant environmental conditions maintained through continual provision of nutrient and removal of wastes is called __________ culture system.
Options- A. continuous
- B. batch
- C. fed-batch
- D. semi continuous Discuss
- 8. An increase in the heat transfer in the stirred tank reactor will be observed at
Options- A. higher cooling water temperature
- B. higher stirrer speed
- C. the removal of baffles from the reactor
- D. slower stirrer speed Discuss
- 9. Population doubling time, td can be expressed as (where ? is the specific growth rate.)
Options- A. log2/?
- B. ln2/?
- C. ?/ln2
- D. ?/log2 Discuss
- 10. A dilatant fluid is one in which the viscosity
Options- A. is constant regardless of the stirrer speed or mixing time
- B. changes during mixing but returns to its original state after mixing
- C. increases with increasing stirrer speed
- D. decreases with increasing stirrer speed Discuss
More questions
Correct Answer: disengagement zone
Correct Answer: provide low shear conditions and are suited for use in shear sensitive procesess
Correct Answer: fed-batch reactor can be used to minimize starch concentrations and thus reduce the viscosity of the medium
Correct Answer: time rate of total amount in rector = rate of addition to reactor -rate of removal + rate of formation
Correct Answer: 2 h
Correct Answer: KL = DAB/Zf
Correct Answer: continuous
Correct Answer: higher stirrer speed
Correct Answer: ln2/?
Correct Answer: increases with increasing stirrer speed
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