Microfiltration of mineral suspensions using a MSD module with rotating ceramic and polymeric membranes

This paper focuses on dynamic microfiltration of CaCO3 suspensions conducted on a modified multishaft disk (MSD) laboratory pilot, which permits to use polymeric membranes. In this study, rotating membrane disks were mounted on the upper shaft. The effect of disk rotating speed, transmembrane pressure (TMP), with or without metal disks on the lower shaft was investigated in terms of the permeate flux. The results showed that the permeate flux could be raised significantly in the presence of metal disks. Polymeric membranes were compared to ceramic ones. It seems that the polymeric membrane produces a higher filtrate flux, but it is prone to particle deposit. Consequently, the overlapping disk is more efficient to remove the membrane cake when using a polymeric membrane. Besides, mean shear rates at the membrane were estimated in this MSD module to investigate their influence on the filtrate flux. Shear rates in a filtration module with a disk (RD) rotating near a stationary membrane were also presented for comparison. The results indicated that in both modules the shear rate is the key parameter controlling the filtrate flux. In addition, it was found that less energy was consumed when using ceramic membranes. This difference would be very large in an industrial scale MSD system.