Abstract:Based on the concentration polarization theory and pore blocking effect, a model was developed to predict organics rejection during ultrafiltration in advanced wastewater treatment. The model was calibrated and validated against data collected from pilot-scale experiments. Results of model validation indicated that the model could well predict the time variations of permeate UV254 during ultrafiltration with absolute relative errors between simulated and observed data less than 10%. Regional sensitivity analysis and uncertainty analysis of model parameters suggested that the model exhibit a robust and reliable structure. The influence of different operating conditions, including filtration time, flux and feed concentration, on permeate concentration was investigated with the developed model. Results indicated that the pore blocking effect dominated in the initial stage of ultrafiltration and increased the rejection rate of organics, whereas concentration polarization effect dominated the rest and decreased rejection. The rejection rate of UV254, with a constant feed concentration of 0.1cm-1, was decreased by 13% when the flux increased from 5×10-5 m/s to 1×10-4m/s. With a constant flux of 5×10-5m/s, however, the permeate UV254 concentration was 50% lower at a feed concentration of 0.1cm-1 than that at 0.2cm-1. Therefore the model could simulate the influences of influent quality and operating conditions on effluent quality for the ultrafiltration process in advanced wastewater treatment, and thus provide decision support for the optimization of ultrafiltration with respect to pretreatment, filtration period and flux.