ABSTRACT
A very convenient classification of solid-liquid separation processes in terms of their modes of action has been given by Purchas. From the point of view of solid-liquid separation pretreatment the terminology of La Mer and Healy is to be preferred because the aggregates of particles arising from flocculation and coagulation. An important factor in the design of a filtration process is the source of the pressure necessary to overcome the resistance to fluid flow caused by the medium and deposited filter cake. In the cake filtration of fine particles it is often found that the first layer of cake deposited will penetrate the filter medium and "blind" it to such an extent that flow virtually ceases. Filter aids may also be used as "precoats" to overcome the problems of blinding and bleeding. It involves the prior deposition of a layer of the aid on the filter medium before filtration is begun.
