Multi-phenomenal macroscopic investigation of cross-flow membrane flux in microfiltration of oil-in-water emulsion, experimental & computational

The primary reasons for reduction of permeate flux in membrane separation processes are cake layer formation and concentration polarization phenomenon. Although pore blocking affects cross membrane flux, but its influence has been neglected in the previous numerical studies. In present study, macroscopic 2D CFD modeling and experimental survey in treatment of oil-in-water emulsion with cellulose acetate (CA) membrane in a cross-flow microfiltration are presented. In order to investigate the simultaneous effects of both phenomena of cake formation and pore blocking, an oil droplet size distribution based on experimental measurements is considered in the modeling. The pore blocking is simulated macroscopically in the microfiltration process. As a main result, by considering membrane governing equations into a 2D domain, i.e. pore blocking phenomenon, the simulation prediction can improve about 15%. Effects of various operational conditions such as trans-membrane pressure (TMP), cross-flow velocity (CFV) and feed oil concentration on permeate flux and process performance are also evaluated. By increasing feed oil concentration from 1000 to 10000 mg/L, the maximum value of oil concentration on membrane surface increases 9.68 times and by increasing CFV from 0.5 to 1.1 m/s, the maximum thickness of concentration polarization (CP) layer decreases 14%. Comparison of model predictions against experimental data for permeate flux indicates acceptable accuracies with a maximum error of 4.62%.