Biochemical Engineering

Question: The maximum solubility of the alkane in the medium is 5 ppm. If the actual dissolved concentration of the alkane in the medium is 1 ppm. what conclusion may be drawn?
[A].

The growth rate is limited by the rate of mass transfer of the alkane into the fermentation medium

[B].

The growth rate is limited by the intrinsic kinetic properties of the cells and not by mass transfer

[C].

The growth rate is neither mass transfer nor kinetically limited

[D].

No conclusion on the growth rate can be withdrawn

Answer: Option D

Explanation:

No answer description available for this question.

Question: An increase in the heat transfer in the stirred tank reactor will be observed at
[A].

higher cooling water temperature

[B].

higher stirrer speed

[C].

the removal of baffles from the reactor

[D].

slower stirrer speed

Answer: Option B

Explanation:

No answer description available for this question.

Question: When liquid is pumped through cooling coil in a stirred tank reactor to cool. Which of the following is not correct?
[A].

If the stirrer speed is increased, the rate will be faster

[B].

Baffles in the tank will increase the rate of cooling

[C].

Faster cooling rates at a slower rate of pumping

[D].

Faster cooling rates at a faster rate of pumping

Answer: Option C

Explanation:

No answer description available for this question.

Question: 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
[A].

zero

[B].

15 mg.l-1.s-1

[C].

10 mg.l-1.s-1

[D].

5 mg.l-1.s-1

Answer: Option B

Explanation:

No answer description available for this question.

Question: The oxygen transfer rate in a bioreactor will increase if
[A].

oil is added

[B].

antifoam is added

[C].

detergent like molecules are added

[D].

increase in the reactor temperature

Answer: Option C

Explanation:

No answer description available for this question.

Question: 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)

Answer: Option C

Explanation:

No answer description available for this question.

Question: The rate limiting step in the movement of oxygen from the gas phase in a bubble to the cell is the movement of oxygen molecules through
[A].

gas-liquid interface

[B].

bubble boundary layer

[C].

bulk liquid

[D].

gas phase

Answer: Option B

Explanation:

No answer description available for this question.

Question: 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
[A].

zero

[B].

3 mg.l-1.s-1

[C].

5 mg.l-1.s-1

[D].

15 mg.l-1.s-1

Answer: Option A

Explanation:

No answer description available for this question.

Question: Which of the following is correct for the off-centre impellers?
[A].

Off-centre impellers can be used with any size reactor

[B].

Off-centre impellers should only be used with reactors with volumes less than 10 m3

[C].

The impeller should never be placed in an off-centre position

[D].

Off-centre impellers can be used when volume is greater than 10 m3

Answer: Option B

Explanation:

No answer description available for this question.

Question: Impeller damage can be minimized by
[A].

using specially designed axial flow impellers

[B].

using radial flow impellers

[C].

using Intermig impellers

[D].

all of the above

Answer: Option A

Explanation:

No answer description available for this question.