Fixed-bed adsorption in drinking water treatment: a critical review on models and parameter estimation

A review is given on the state of modelling of fixed-bed adsorption processes in drinking water treatment with special consideration of parameter estimation. In particular, the Homogenous Surface Diffusion Model (HSDM) and the Linear Driving Force Model (LDF model) are compared and evaluated with respect to availability of the required model parameters. In this context, methods for predicting equilibrium and mass transfer parameters are critically discussed under particular consideration of the specific drinking water characteristics. Feasibilities and limits of different approaches for estimating equilibrium parameters are exemplarily shown. In particular, Polanyi's potential theory, a modified Freundlich equation, and the adsorption analysis for complex mixture solutions are considered. Furthermore, empirical correlations for predicting mass transfer coefficients for single-solute and multi-component adsorbate systems are presented and evaluated.