Modelling the NOM uptake by anion exchange resins in drinking water plants

In drinking water treatment plants, the removal of natural organic matter (NOM) is an essential aim to improve the final water quality and to reduce the formation of disinfection by-products. The objective of the present study was to compare the performance of different macroporous anion exchange resins (AERs) with regard to their NOM removal under drinking waters conditions. NOM removal at neutral pH was assessed by measuring the decrease of the dissolved organic carbon concentration in equilibrium experiments. Further, the fictive component approach (adsorption analysis) was applied to describe the competitive adsorption equilibria of the complex NOM system. Due to their relevance for fixed-bed filter design, breakthrough curves (BTCs) were measured and modelled by the homogeneous surface diffusion model with the linear driving force approach for surface diffusion combined with the ideal adsorbed solution theory for competitive adsorption. These model approaches, well known from activated carbon adsorption, were used in the present study to describe NOM adsorption onto AERs. The required mass transfer coefficients were obtained by empirical correlations. The applicability of the BTC model was verified with the experimental data of NOM uptake onto one selected AER.