The active cake layer filtration process is one of the unique features of the ceramic flat sheet membrane technology. A cake layer can function as additional filter bed for enhanced removal of very small particles and colloidal fractions. It can also be used to adsorb dissolved water contents. A formed cake layer can also function as protective coating to minimize membrane biofouling and scaling effects.
Common cake layer particles or flocs are based on metal oxides, e.g. from Fe and Mn but they can also be based on Alum or hardness precipitants.
Cake layer particle sizes below 0.4 µm are common. Membranes with larger pores sizes or a wide pore size distribution range will be affected by performance declines, e. g. due to pore blockages or reduced filtered water quality.
In general, the smaller the pore size and the tighter the pore size distribution the better the suitability for cake layer filtration processes.