“…The flux of NF membranes was related to their hydrophobicity and charges. Fouling by NOM adsorption was an important factor in hydrophobic and positively charged membranes, whereas it was negligible for hydrophilic and negatively charged membranes (Lee et al 2007). Many factors affect membrane fouling by natural organic matter (NOM), including the nature of the NOM (size, hydrophobicity, and charge), the membrane (hydrophobicity, charge, and surface roughness), the solution (pH, ionic strength, hardness ion concentration) and the hydrodynamic systems (solution flux, surface shear) (Taniguchi et al 2003;Farahbakhsh et al 2004).…”