Application of Hydrocyclone for Cell Separation in Mammalian Cell Perfusion Cultures

The present work was carried out to investigate the possibility of hydrocyclone application for cell separation in mammalian cell perfusion cultures. Firstly, experiments were carried out to evaluate the physical characteristics controlling the separation performance of the hydrocyclone as well as the effect of the different operating conditions and different hydrocyclone geometrical dimensions on the separation process. Increasing the pressure applied by the hydrocyclone increased the feed and the underflow rates as well as the flow split and the flow ratio. In addition, decreasing the overflow diameter increased the applied pressure and accordingly the flow ratio and the separation efficiency of the hydrocyclone. Moreover, operating the hydrocyclone at pressures ranging from 0.85 to 1.40 bar is favorable, since the hydrocyclone performance is expected to be constant in this range. Due to the high flow rates during hydrocyclone operation, and to avoid the complete washout of bioreactor content, the hydrocyclone was intermittently operated during the experimental work. The second part of the work aimed to study the effect of different pressures generated by the hydrocyclone on the cell viability and the separation efficiency using two cell lines, BHK and HeLa cells. The separation efficiency increased by increasing the pressure. Also, the viability for both cell lines was not markedly affected by the applied pressures, and this was attributed to the short residence time of cells inside the hydrocyclone (from 0.18 to 0.1 s). Also, the viability of the cells in the overflow markedly decreased compared to the viability of the cells in the underflow, which was referred to the longer residence time of these cells inside the hydrocyclone compared to the cells found in the underflow. In addition, the possible collision between cells due to the reversal of the flow may affect the viability of cells found in the overflow, where the inner vortex moves upwards to the overflow and the outer vortex moves downwards to the underflow.