Modeling equilibrium adsorption of 2-methylisoborneol and geosmin in natural waters

The impact of natural organic matter (NOM) on the adsorption of the taste and odor causing compounds 2-methylisoborneol (MIB) and geosmin by powdered activated carbon was investigated. Equilibrium experiments showed that adsorption of MIB and geosmin in natural waters was an order of magnitude lower than single-solute adsorption. It was found that when the equilibrium concentration was expressed as a percentage of the initial concentration, the removal of MIB and geosmin in natural waters was independent of initial concentration. This relationship was also mathematically derived from the ideal adsorbed solution theorem when the concentration of the target compound was assumed to be much lower than the concentration of the competing NOM. A single equivalent background compound (EBC) was used to simulate the competitive effects of the background NOM and describe the adsorption of MIB and geosmin. The same EBC was found to be applicable to both MIB and geosmin and, at different initial concentrations, for all four waters. Three of the waters had similar ratios of EBC initial concentration to total organic carbon concentration.