Institute for Biotechnology and Bioengineering, Centro de Eng. Biológica, University of Minho, Braga, Portugal.
Biotechnol Prog. 2012 Nov-Dec;28(6):1534-41. doi: 10.1002/btpr.1636. Epub 2012 Nov 1.
Filtration of an isotonic suspension of baker's yeast through a 0.45-μm membrane was studied at two different pressures, 40 and 80 kPa, for yeast concentrations ranging from 0.14 to 51 kg/m(3) (dry weight). For a yeast volume fraction above 0.06 (~21.8 kg/m(3) ), the porosity of the yeast cake is less dependent on the suspension concentration. For highly diluted suspensions, the specific cake resistance approaches a minimum that depends on the filtration pressure. Correlation functions of cake porosity and specific cake resistance were obtained for the concentration range investigated showing that the Kozeny-Carman coefficient increases when the applied pressure increases. Both filtration pressure and slurry concentration can be process controlled. In the range of moderate yeast concentration, the filtrate flux may be increased by manipulating the filtration pressure and the slurry concentration, thereby improving the overall process efficiency. The complex behavior of yeast cakes at high slurry concentration can be described by a conventional model as long as part of yeast cells are assumed to form aggregates, which behave as single bigger particles. The aggregation effect may be accounted for using a binary mixture model.
通过 0.45μm 膜对面包酵母的等渗悬浮液进行过滤的研究在两个不同的压力下进行，即 40 和 80kPa，酵母浓度范围为 0.14 至 51kg/m³（干重）。对于酵母体积分数高于 0.06（~21.8kg/m³），酵母饼的孔隙率不太依赖于悬浮液浓度。对于高度稀释的悬浮液，比滤饼阻力接近取决于过滤压力的最小值。在所研究的浓度范围内获得了滤饼孔隙率和比滤饼阻力的相关函数，表明 Kozeny-Carman 系数随着施加压力的增加而增加。过滤压力和浆料浓度都可以进行过程控制。在中等酵母浓度范围内，通过操纵过滤压力和浆料浓度可以提高滤液通量，从而提高整体过程效率。只要假设一部分酵母细胞形成团聚体，这些团聚体表现为单个较大的颗粒，就可以用传统模型来描述高浆料浓度下酵母饼的复杂行为。可以使用二元混合物模型来解释团聚效应。
