As fouling has always been a major drawback of membrane technology, qualitative and quantitative understanding of membrane fouling mechanisms therefore becomes vital in order to help push membrane separation technologies forward. In this study, firstly, self-cleaning Polysulfone(PSf) membranes were synthesized by incorporation of WO_3nanoparticles(0–2 wt%) and subsequent UV irradiation for efficient ultrafiltration(UF)of landfill leachate and dairy wastewater. The membrane surface properties were characterized by scanning electron microscopy(SEM) and contact angle analysis. It was found that UV-irradiated membranes exhibited higher percent COD removals due to the hydrophilicity and photocatalytic properties of nano-WO_3. Subsequently, in order to analyze the fouling behavior of the membranes, a set of experimental data from cross-flow ultrafiltration of municipal landfill leachate and industrial dairy wastewater at 25 °C was obtained. A new model of membrane fouling was proposed based on a resistance in series concept and was fitted well with all experimental data sets.Almost all relative errors of prediction provided by the proposed model were less than 2.5%. In addition, it was revealed that this newly-developed model exhibited smooth transition between the common successive twostep pore blockage-cake filtration phenomena and thus eliminates the need to use separate equations for different mechanisms. As this has, a fauling has always been a major drawback of membrane technology, qualitative and quantitative understanding of membrane fouling mechanisms therefore becomes vital in order to help push membrane separation technologies forward. In this study, first, self-cleaning Polysulfone (PSf) membranes were synthesized by incorporation of WO_3nanoparticles (0-2 wt%) and subsequent UV irradiation for efficient ultrafiltration (UF) of landfill leachate and dairy wastewater. The membrane surface properties were characterized by scanning electron microscopy (SEM) and contact angle analysis. It was found that UV -irradiated membranes showed higher percent COD removals due to the hydrophilicity and photocatalytic properties of nano-WO_3. In order to analyze the fouling behavior of the membranes, a set of experimental data from cross-flow ultrafiltration of municipal landfill leachate and industrial dairy wastewater at 25 ° C was obtained. A new model of membrane fouling was proposed bas ed on a resistance in series concept and was fitted well with all experimental data sets. Almost all relative errors of prediction provided by the proposed model were less than 2.5%. In addition, it was revealed that this newly-developed model profiling smooth transition between the common successive twostep pore blockage-cake filtration phenomena and thus eliminates the need to use separate equations for different mechanisms.