Question

The rate of oxygen tranfer is given by equation ____________

(a) dCL/dt = KLa (C* – CL)

(b) dCL/dt = KLa (C*)

(c) dCL/dn = KLa (CL)

(d) dCL/dn = KLa (C* – CL)

This question was addressed to me in an online interview.

The above asked question is from Aeration and Agitation in section Aeration and Agitation of Fermentation Technology

Answer 1

The correct answer is (a) dCL/dt = KLa (C* – CL)

To explain I would say: The rate of oxygen transfer from air bubble to liquid phase is described as: dCL/dt = KLa (C* – CL) where, CL is the concentration of DO in fermented broth, dCL/dt is the change in oxygen concentration over a period of time, KL is the mass transfer coefficient, a is the gas/liquid interface area per liquid volume, C* is the saturated DO concentration.