An empirical model based on logistic equation coupled with gel polarization/film mathematical model based on cake filtration theory, have been developed in the present study. Unlike the factors needed to be determined in convection-diffusion model, the factors in this empirical model were easier to achieve. In this paper, the estimation of gel polarization process in two different UF processes (stirred and non-stirred conditions) had been carried out through flux declining investigation. The results shown that the R-2 value of gel formation process simulated by logistic model was 0.9941, and 0.9971 for gel elimination process, indicating this equation was reliable and effective. Moreover, both cake filtration model and convection-diffusion model were not accurate to simulate gel formation (elimination) process accurately, because the parameters were hard to be determined, and the R2 values were also too low to get a suitable simulation. Thus, this empirical model based on logistic equation has been found to predict the formation and elimination of polarized layer reasonably, once the three parameters (initial, middle and final values of flux) were get along with the operating condition. Moreover, surface and cross-sectional morphologies of membrane were investigated by scanning electron microscope (SEM), and chemical bond variation between membrane and fouled membrane was studied by ATR-FTIR, which made an advanced certificate of this UF process. (C) 2013 Elsevier B.V. All rights reserved.