Pressure-dependent permeate flux in ultra- and microfiltration

The effect of applied pressure on the permeate flux in cross-flow ultrafilt ration (UF) and microfiltration (MF) was investigated both theoretically an d experimentally In UF and MF processes, the permeate fluxes are controlled by concentration polarization and cake formation over the membrane surface . As a better understanding of concentration polarization and cake formatio n becomes available, the permeate flux under any pressure can be theoretica lly predicted. Experiments were conducted in a ceramic tubular cross-flow f ilter with silica colloids of a narrow size distribution (model colloids). The pressure-dependent flux of the model colloidal suspension in cross-flow filtration was investigated under various experimental conditions. The exp erimental measurements were compared with the theoretical predictions, and the results showed that the pressure-dependent permeate flux in cross-flow filtration can be adequately predicted. Furthermore, theory and experiments demonstrated that the performance and operating state of UF and MF could b e well characterized by the so-called "characteristic pressure" of the proc ess.