The ease with which data may be entered into, and extracted from, electronic databases using Internet based applications is providing new opportunities for understanding and modelling of complex systems. An expert system for solid-liquid separation equipment selection and elimination, using an Internet based interface coupled to such a database, is described. Also, a database containing filtration constants for a variety of different minerals is provided and an illustration of how these constants may be used in mathematical simulations of filtration processes is given. A simple experimental procedure, which can be performed using only a single test where the pressure during filtration is incrementally increased, can provide the necessary filtration constants for the simulation procedure. Hence, the database of filtration constants can be easily expanded using experimental data from this, or similar procedures. An experimental technique that measured the in situ concentration of the forming filter cake, via electrical conductivity measurements, was used to compare the simulated local cake concentrations, using the filtration constants, against the measured ones. The agreement between the simulated cake concentrations and the measured ones was excellent. (C) 2002 Elsevier Science Ltd. All rights reserved.