Modeling geosmin removal in a full-scale filter

Abstract

Taste and odor compounds affect drinking water safety perception and may drive consumers to less secure water sources. Adsorption, using powered activated carbon, is the most common method to remove these compounds but greatly increases the amount of sludge generated. Another way of removing taste and odor compounds is to use filters with granular activated carbon (GAC) but little is still known on how to design them. In this work, the homogeneous surface diffusion model (HSDM) was used to model bench-scale kinetic and isotherm experiments and to simulate the removal of geosmin in a full-scale GAC filter. Geosmin adsorption isotherm was best described by the Freundlich model in all used carbons and film resistance (Kf) was more relevant to adsorption kinetics than pore diffusion (Ds). The simulation showed that in a filter with an empty bed contact time of 5 minutes and raw water with geosmin concentrations of 50, 75, and 100 ng.L-1, the effluent would exceed the trash-hold concentration (10 ng.L-1) in 98, 77, and 66 days, respectively, without considering biological removal.