Agitation and Aeration Objective Questions and Answers

22. Which of the following is not considered among the three best-known theories of interphase mass transfer?

23. Which of the following is most likely to cause an increase in the rate of oxygen transfer into a particular aerated fermentation system?

A. Addition of antifoams

B. Increase in temperature

C. Increase in stirrer speed

D. Both (a) and (b)

Discussion

24. 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

25. Gas hold up, characterizing the hydrodynamics in a fermenter, mainly depends on the

A. superficial gas velocity

26. Turbine impeller consists of flat impeller blades with

A. a vertical pitch welded directly to the shaft

B. a angled pitch welded directly to the shaft

C. a vertical pitch welded to a horizontal disk

D. a angled pitch welded to a horizontal disk

Discussion

27. An aerated bioreactor will increase oxygen transfer rates with the addition of detergents because it

A. enhances bubble coalescence

B. causes bubbles to expand

C. discourages bubble coalescence

D. increases the surface tension of the liquid

Discussion

28. Vortexing in stirred tank reactors can be prevented by

A. installing baffles in the reactor

B. shifting the impeller to an off-centre position

C. Both (a) and (b)

D. using axial flow impellers

Discussion

Biochemical Engineering Objective Questions { Agitation and Aeration }