Application of rotational vibration in a submerged hollow fibre membrane system for bioseparation of high concentration yeast suspensions

Abstract

A novel submerged rotational vibration membrane system was investigated using high concentration yeast suspensions to demonstrate the capability of this system for the separation of high concentration biomass. The critical flux and shear rate for this system can be correlated by the expression, Jcritical=1.2γ̅0.55, for the filtration of 200 g/L yeast suspension. Good fouling control performance as indicated by low and stable TMP at approximately 13 kPa as well as high protein transmission of 84% was maintained over 26 h of filtration using 200 g/L yeast suspension at a constant permeate flux of 15 L/m2 h before a rapid TMP rise was observed mainly due to the increase of feed concentration. It was determined that there is a limiting concentration, defined here as the critical concentration point, below which low and stable TMP operation can be maintained and above which rapid TMP rise was observed. Fractionation analysis of the foulant layer at the end of long term filtration experiments showed that majority of fouling was loose and reversible, which can be easily recovered by simple rinsing. The implementation of intermittent shear enhancement and periodical relaxation were found to be effective in fouling limitation, which extended the critical concentration point. However, applying periodical backwash using the permeate is not advantageous as the permeate contains protein and carbohydrate which can cause internal fouling of the pores.