Mass transfer coefficient evaluation for lab scale fermenter using sodium sulphite oxidation method

Abstract

Oxygen transfer is often the rate-limiting step in the aerobic bioprocess due to the low solubility of oxygen inside the aqueous solution. The rate of reaction is such that as oxygen enters the liquid phase, it is immediately consumed to oxidize the sulfite so that the rate of oxidation is equivalent to the oxygen-transfer rate.  Reaction rate often determined by titration is much faster than oxygen transfer rate so that gas- liquid mass transfer is the rate controlling step. The current study involves using central composite design, a statistical technique to find out the parameter conditions for the optimum volumetric mass transfer coefficient in a lab scale (2L) fermentor. The optimum volumetric mass transfer coefficient was found to lie outside the range of parameters studied and analytical expressions was obtained to predict the volumetric mass transfer coefficients for the parameter ranges studied using response surface methodology.  The analytical expression was found to be significantly valid based on ANOVA results.

Keywords: Aerobic bioprocess; Sodium sulphite oxidation process; Mass transfer coefficient; Central composite design