Dynamic model for soluble Mn2+ removal by oxide-coated filter media

A process model for soluble Mn2+ removal by oxide-coated media filtration was developed, incorporating a modified Gnielinski mass transfer correlation for boundary layer transport, hydrodynamic dispersion, the Freundlich isotherm, and a modified Keinath correlation for intracoating surface diffusion. The available fraction of equilibrium sorption capacity was the calibration parameter used for the sorptive process mode. For the process mode of continuous regeneration by free chlorine, the sorbed Mn2+ oxidation rate constant was an additional calibration parameter, and the two parameters were uncorrelated. The calibrated model was predictive for laboratory column effluent profiles under dynamic influent boundary conditions of sorption followed by desorption over ranges of pH, flow rate, ionic strength, and (Ca2-). The model also satisfactorily accounted for oxidative Mn2+ removal over a range of process conditions for both synthetic and ''naturally'' coated media. Model structure was suggested by results of fundamental physical and chemical characterization of filter media from water treatment plants.