Further development of filtration theory

The filtration theory presented here is only very basic and the assumptions on which it is built are often too simplistic. This so-called classical filtration 

Starting with the medium resistance, R, which can be determined from the intercept in constant pressure filtration (section 9.3.1), this is subject to great uncertainty and in practice often comes out either unrealistically small or even negative. Tiller et al have pointed out that the plots of tIV against V have marked curvature at the start of the filtration experiment and this can easily be missed. They defined the intercept values as false medium resistance and showed that a good value of medium resistance is obtained only if the ordinate of the first experimental point (1/0 is close to the intercept value. 

It is now certain that the only truly rigorous approach to filtration theory is by using point values of a within the cake itself and those can only be obtained from studies of flow and local porosities in practical cakes. This is inevitably very complicated and beyond the scope of this book. The reader is referred to the already mentioned review by Tiller et al and to a theoretical paper by Wakeman . 

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