Modelling the uptake of natural organic matter (NOM) by different granular sorbent media

The removal of natural organic matter (NOM) by four different granular sorbent media, activated carbon, an anion exchange resin, activated alumina and granular ferric hydroxide, respectively, was investigated. Isotherm data, kinetic parameters and column breakthrough curves were determined. Adsorption analysis was applied to describe sorption equilibria, and the film-homogeneous surface diffusion model was used to predict NOM uptake in fixed-bed columns. The results show that NOM adsorption by activated carbon and activated alumina could be modelled quite well by the approach used. NOM uptake by the anion exchange resin could be predicted with respect to capacity while two kinetic parameters were obviously not sufficient to describe the rate of uptake correctly. NOM adsorption by granular ferric hydroxide proved to be a very slow process that could not be predicted using parameters derived from batch data.