Application of computational fluid dynamics to ε-poly-L-lysine fermentation of different impeller combinations

The influence of two kinds of different impeller combinations(one impeller combination including two six-straight-blade-turbines,the other including six-straight-blade-turbine lower and propeller upper) on mass transfer,mixing effect and shear stress of 5 L gas-liquid bioreactor was studied with computational fluid dynamics(CFD).Meanwhile,using these two kinds of impeller combinations in laboratory-scale e-poly-L-lysine fermentation,the result shows that the different impeller combinations bring significantly different phenomena.Compared with bioreactor 1,bioreactor 2 has a huge improvement in cell respiration,and the oxygen uptake rate(OUR) and carbon dioxide evolution rate(CER) are 23% and 32% higher.Furthermore,the synthesis of strength of e-poly-L-lysine is increase by 8% and the biggest difference of the biomass dry mass at the same time is 40% higher.