Volumetric Oxygen Mass Transfer Coefficient Determination and Hydrodynamic Optimization of Polyhydroxyalkanoate Production with Vegetal Oil as Carbon Source

Abstract

The effects of aeration rate and agitation speed on the production of Polyhydroxyalkanoates (PHA’s) by Burkholderia cepacia B27 in a batch fermenter were investigated. Central composite design (CCD) technique was used to develop an empirical model to find the best hydrodynamic conditions to demonstrate the high influence of rheological culture over biomass production and PHA accumulation. The agitation speed and aeration rates were between 120 to 515 rpm and 4.3 to 22 ?? ??????^-1, respectively. This values range was selected due to the aeration and agitation restriction of bioreactor. A dynamic method was applied to measure the volumetric oxygen mass transfer, which has a critical influence on biomass development on the overall process. Results revealed the agitation was the most important factor to PHAs accumulation. Furthermore, other parameters including bacteria growth was affected by the mass transfer, dissolved oxygen and broth viscosity, therefore agitation speed and aeration rate had a significant effect over strain and its production efficiency. Maximum PHA’s concentration reached was 8.72 ?? ??^-1 at 24 h of fermentation time with aeration rate and agitation speed at 13.5 ?? ??????^-1 and 310 rpm, respectively.