Predictive models and factors affecting natural organic matter (NOM) rejection and flux decline in ultrafiltration (UF) membranes Original Research Article

Prediction equations for NOM rejection were formulated using parameters, including specific UV absorbance [SUVA = UV absorbance at 254 nm/dissolved organic matter (DOC)] and a fk ratio [a ratio of water permeability (f) to the mass transfer coefficient (k)], which have been found to influence aspects of NOM and operating conditions, respectively. Attempts were made to formulate relationships between adsorption resistance (Ra) and interfacial membrane concentration (Cm), and specifically between the amount of NOM absorbed (mg C/cm2) and the Ra. Flux decline was also formulated in two ways: (1) by the (so-called) empirical flux-decline equation with three flux-decline coefficients, and (2) by the adsorption flux-decline model with two NOM adsorption terms between bulk, the NOM and the membrane surface and an existing NOM adsorption layer.