Agitation and Aeration – Section 2

11. Which of the following is not classified as an axial flow impeller?

A. A propeller
B. A marine impeller
C. A Rushton turbine
D. A hydrofoil impeller

Correct Answer: C. A Rushton turbine

12. Power number (Np) is also known as

A. Froude’s number
B. Bond’s number
C. Newton’s number
D. Rayleigh’s number

Correct Answer: C. Newton’s number

13. Flooding is a condition/phenomenon which occurs in a bioreactor when

A. The air escapes without being distributed by the agitator
B. The fermenter medium spills out the reactor due to foaming
C. The volume of foam is more than the volume of broth
D. None of the above

Correct Answer: A. The air escapes without being distributed by the agitator

14. A cylindrical reactor has a liquid volume of 100,000 liters. It has an aspect ratio of the channel height to width of 1:1. The height of the liquid in the reactor will be approximate:

A. 1.0 m
B. 3.0 m
C. 5.0 m
D. 7.0 m

Correct Answer: C. 5.0 m

15. Detergent like substances produced by microorganisms during fermentation will lead to

A. decrease the surface tension of the liquid
B. accumulate at the gas-liquid interface
C. decrease the rate of bubble coalescence
D. all of the above

Correct Answer: D. all of the above

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