2009 Volume 46 Issue 4 Pages 250-260
The transition phenomenon, which is a feature of the filtration properties of non-woven fabric filter, is the change in filtration mode during filtration from the first stage of deep bed filtration to the second stage of surface blocking filtration or the cake filtration. In this study the effect of filter structure in depth direction on the transition phenomenon was studied with the filters prepared by layering three types of polypropylene non-woven fabric filters and binary mixture suspension of uniform PMMA particles. The change in the apparent pore size distribution of prepared filters was measured by the differential flow method. In the case of filters stacked with the same type of filters the change in the filtration performance by the stacking could be explained by the change in the surface blocking filtration condition in the first stage filtration period and it could be roughly predicted from the change in the apparent pore size distribution. But in the case of the filters stacked with different types of filters the change in the filtration performance did not show clear trends with the stacking condition and could not be explained from the change in the apparent pore size distribution.
