Characterization of non-Newtonian behavior during mixing of bacterial cellulose in a bioreactor

The mixing properties of bacterial cellulose (BC) in an aerated and agitated vessel are described. To characterize the mixing of BC culture broth, which can affect the productivity of BC, non-Newtonian behavior during mixing of a 1% BC suspension was studied using an image processor capable of detecting decoloration of a pH indicator and was compared with that of a 2% carboxy methyl cellulose (CMC) solution. CMC solution was mixed homogeneously within the measured range of agitation speed, but the BC suspension was not mixed homogeneously at agitation speeds lower than 15 rps because mixing was delayed in some areas of the vessel. A possible reason for the inhomogeneity of the BC suspension at low agitation speeds is the non-Newtonian behavior which increases viscosity at low shear rates.