Question

The smaller bubbles are sensitive than larger bubbles?

(a) True

(b) False

I had been asked this question during an interview for a job.

This intriguing question comes from Oxygen Transfer in Fermenters topic in portion Mass Transfer of Bioprocess Engineering

Answer 1

The correct choice is (a) True

For explanation: kL in fermentation liquids is about 3-4×10^-4 m s^-1 for bubbles greater than 2-3 mm diameter; this can be reduced to 1×10^-4m s^-1 for smaller bubbles depending on bubble rigidity. Once the bubbles are above 2-3 mm in size, kL is relatively constant and insensitive to conditions.