Question

Which type of fermenter is used mainly for mixing?

(a) Air-Lift fermenter

(b) Stirred Tank fermenter

(c) Fluidised Bed bioreactor

(d) Packed Bed bioreactor

I got this question in an international level competition.

This interesting question is from Mixing in chapter Fluid Flow and Mixing of Bioprocess Engineering

Answer 1

Correct answer is (b) Stirred Tank fermenter

To explain I would say: Mixing is usually carried out in a stirred tank; Stirred tanks are usually cylindrical in shape. If possible, the base of the tank is rounded at the edges rather than angled; this eliminates sharp corners and pockets into which fluid currents may not penetrate and discourages formation of stagnant regions.