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- Question
Surface renewal theory predicts that the mass transfer coefficient is
Options- A. directly proportional to the square root of the molecular diffusivity
- B. inversely proportional to the square root of the molecular diffusivity
- C. directly proportional to the cube root of the molecular diffusivity
- D. indirectly proportional to the cube root of the molecular diffusivity
- Correct Answer
- directly proportional to the square root of the molecular diffusivity
- 1. Penetration theory assumes that turbulent eddies travel from the bulk of the phase to the interface where they remain constant for a constant exposure time (te). The model correlating KL, mass transfer coefficient and DAB, diffusivity can be expressed as
Options- A. KL = 2(DAB/?te)0.25
- B. KL = 2(DAB/?te)0.5
- C. KL = 2(DAB/?te)0.75
- D. KL = 2(DAB/?te) Discuss
- 2. Which have the maximum resistance while transferring carbon dioxide from the bulk liquid to an air bubble?
Options- A. Moving through the gas liquid interface
- B. Moving through the bubble boundary layer
- C. Moving across the cell membrane
- D. Moving through the bulk liquid Discuss
- 3. The lowest yield of ATP /is in
Options- A. fermentation
- B. aerobic respiration
- C. anaerobic respiration
- D. same in (a), (b) and (c) Discuss
- 4. The growth of an organism on glucose is described by the following Monod model parameters: ?m = 0.5 h-1 and Ks =0.1 g.l-1, if the concentration of glucose in the feed is 10 g.l-1 and the dilution rate is set to 0.4 h-1, then the steady state concentration of glucose in the effluent will be
Options- A. 0 g.l-1
- B. 0.5 g.l-1
- C. 1.0 g.l-1
- D. 10 g.l-1 Discuss
- 5. Immobilized cell reactors for wastewater treatment have the advantage of having/being
Options- A. higher cell concentration
- B. more stable and prevent washout
- C. higher dilution rate before the cells washout
- D. all of the above Discuss
- 6. Which of the following would be best described as an axial flow impeller?
Options- A. An impeller with blades pitched at 45° to the vertical
- B. An impeller which directs liquid flow towards the base of the reactor
- C. Both (a) and (b)
- D. An impeller with blades pitched at 75° to the vertical Discuss
- 7. Which of the following type(s) of stirrer can be used for microbiological processes?
Options- A. Mig
- B. Intermig
- C. Turbine
- D. All of these Discuss
- 8. Which of the following is most likely to cause an increase in the rate of oxygen transfer into a particular aerated fermentation system?
Options- A. Addition of antifoams
- B. Increase in temperature
- C. Increase in stirrer speed
- D. Both (a) and (b) Discuss
- 9. Which of the following will have the highest surface area available for oxygen transfer?
Options- A. A shake flask
- B. A standing test tube
- C. A non-sparged stirred tank reactor agitated at 400 rpm
- D. A sparged stirred tank reactor agitated at 400 rpm Discuss
- 10. At 25°C, the saturation concentration of oxygen in water is 1.26 mmol/l and the partial pressure of oxygen is 1 atm. The Henry's law constant will be
Options- A. 0.793atml/mmol
- B. 0.207atml/mmol
- C. 1.26 atml/mmol
- D. 8.74 atml/mmol Discuss
Agitation and Aeration problems
Search Results
Correct Answer: KL = 2(DAB/?te)0.5
Correct Answer: Moving through the bubble boundary layer
Correct Answer: fermentation
Correct Answer: 0.5 g.l-1
Correct Answer: all of the above
Correct Answer: Both (a) and (b)
Correct Answer: All of these
Correct Answer: Increase in stirrer speed
Correct Answer: A sparged stirred tank reactor agitated at 400 rpm
Correct Answer: 0.793atml/mmol
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