A chemically enhanced backwash model for predicting the instantaneous transmembrane pressure of flat sheet membranes in constant flow rate mode

Abstract

In this study, a new model was proposed based on the cascade process of the chemical reaction and the physical removal mechanism to predict the instantaneous transmembrane pressure (p(t)) of yeast-fouled 0.1 μm polyacrylonitrile (PAN) membranes in the chemically enhanced backwash (CEB) process. The results indicated that the model predictions were in good agreement with the experimental data. Additionally, the transition point of the CEB mechanism, which changed from a combined cleaning (pore cleaning and cake cleaning) mechanism to an individual cake cleaning mechanism, appeared earlier at higher NaOCl concentrations or CEB fluxes. The corresponding available membrane area ratio also tended to stabilise earlier. In addition, the model predictions for different suspensions or solutions, membranes (0.1 μm polyethersulfone (PES) and polyvinylidene fluoride (PVDF) membranes), and chemical reagents were also in good agreement with the experimental data. Moreover, the integral of p(t) was used to correct Masse's energy consumption equation. The results show that the calculation method for the corrected equation is theoretically more accurate. Lower total energy consumption was obtained at a higher NaOCl concentration or lower CEB flux.