Colloidal membrane fouling mechanisms were modeled for experimental data provided for nanofiltration of surface water by single and hybrid membrane systems.The hybrid system is composed of coagulation/activated carbon adsorption and bare polyethersulfone or mixed-matrix membranes. The comprehensive modeling of these membrane systems was performed by three explicit equations to evaluate the effects of combined cake-filtration and pore-blocking on the fouling processes. These equations were derived from Darcy's law applied under constant operating pressure. The results showed that by using the nonlinear regression method, the combined cake-filtration/pore-blocking models demonstrated more accurate fits to the experimental permeate volume data compared to individual blocking models. The accuracy achieved by such nonlinear fits is expressed in terms of a mean squared error of approximately 10 −10 (m 3 /m 2 ) 2 and R 2 > 0.999. Furthermore, the impact of a pretreatment stage and the type of membrane used to prevent or reduce the fouling are also investigated. Experimental results reveal that the colloidal fouling depends on the type of membrane and the characteristics of raw water and is not only related to the cake filtration.

Providing potable water will be a challenge for humanity over the next years. In this research, water samples from the Gamasiab River (Iran) were purified to achieve drinking water by applying coagulation, conventional filtration in combination with the nanofiltration process. By using poly aluminum chloride as a coagulant, the turbidity decreased by 96.4%. The turbidity and COD decreased by 98.82% and 32.7%, respectively, via passing the effluent through the activated carbon. Membranes were made of polyethersulfone (PES). Cesium hydrogen phosphotungstic acid (Cs0.5H2.5PW12O40 as CsPW) nanoparticles were incorporated into the polymer matrix to improve the hydrophilicity. The morphology of membranes was studied using the FE‐SEM and AFM. The pure water flux and contact angle for the sulfonated PES with 1.5 wt.% CsPW were 51.9 kg/m2 h and 55.49 °, respectively. The percentage of the turbidity, conductivity, TDS, and COD removal was found to be 99.9, 89.3, 89.3, and 86.6%, respectively, after the hybrid process. The removal of calcium, magnesium, nitrate, chloride, sodium, sulfate, and bicarbonate ions was 90.5, 83.4, 87.9, 60.7, 49, 86, and 80.5%, respectively. Based on these results, the river water meets the standards for drinking water after being purified by applying the aforementioned coagulation/filtration and nanofiltration processes. Practitioner Points The treatment of the Gamasiab River (Iran) was selected for this study to produce potable water. A hybrid systematic coagulation/filtration/nanofiltration (NF) was considered. Water quality parameters were measured and compared with the standard values. The cesium hydrogen phosphotungstic acid was incorporated into the NF to increase the hydrophilicity and water flux. Polyethersulfone was sulfonated to add the sulfonyl group to the polymer.