it would depend on the kind of purification one would like to do, like bio waster water, heavy metal, particulate etc. But speaking in generic term, one would look at porosity and the pressure bearing capacity of the membrane as the starting point

I would recommend the packing density of clay as well as flow rate of water. In other words, the packing efficiency is dictated the particle size distribution used after heat treatment.

I am working on the modeling of the clay pours activity in the mud pots ......please help in this view..........