Question

Bubble column reactor cannot be used for?

(a) Low viscous medium

(b) High viscous medium

(c) Liquid state medium

(d) Solid state medium

I got this question in a job interview.

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

Answer 1

Right answer is (b) High viscous medium

To explain: Bubble column reactor cannot be used for highly viscous medium. Pattern of gas bubbles in a bubble column reactor is dependent on the gas superficial velocity. Gas velocity should be 1-4 cm per second for uniform bubbles throughout medium which will provide proper mixing. If gas velocity is higher or lower than uniform bubbles will not be produced, thus when bubbles coalesce produces differences in fluid density which will disturb air flow rate.