Dual-objective for the mechanism of membrane fouling in the early stage of filtration and determination of cleaning frequency: A novel combined model

It is great importance to clarify the mechanism of the membrane fouling in the early stage of filtration. In this study, a novel model based on the loss of effective filtration area was established to predict the variation of the transmembrane pressure (TMP) at the constant flux mode. The coefficient of available membrane filtration area (ω) was adopted to describe the inflection point varying from combined pore blocking and cake filtration mode to individual cake filtration mode. Model simulations could predict reasonably the rise of transmembrane pressure (TMP) with correlation coefficient of R2 > 0.99. The reliability of the model was evaluated under different operating conditions (flux and stirring speeds) and feed concentrations, wherein the flux presented higher contribution to TMP, resistance of cake filtration (Rc) and resistance of intermediate pore blocking (Ri) than others. The accuracy of predictions of the proposed model was higher than other previous models. Moreover, the wide adaptability of the model was validated by using various real wastewater as feed suspensions. Furthermore, the calculation of the timing of the cake layer formation from the proposed model provided an instructional suggestion for the determination of the cleaning frequency. In summary, the proposed model sheds light on the fouling mechanism in the early stage of filtration and provides guidance to the strategy of cleaning protocols in MBR operations.