Question

Coalescence is appropriate for oxygen transfer in bubbles?

(a) True

(b) False

This question was posed to me at a job interview.

My question is from Oxygen Transfer in Fermenters topic in division Mass Transfer of Bioprocess Engineering

Answer 1

Correct option is (b) False

The best explanation: Coalescence of small bubbles into bigger bubbles is generally undesirable because it reduces the total interfacial area and gas hold-up. Frequency of coalescence depends mainly on the liquid properties. In a coalescing liquid, a large fraction of bubble collisions results in the formation of bigger bubbles, while in non-coalescing liquids colliding bubbles do not coalesce readily. Salts act to suppress coalescence; therefore, fermentation media are usually non-coalescing to some extent depending on com- position. This is an advantage for oxygen mass transfer.