Mathematical model of the non-steady-state adsorption and biodegradation capacities of BAC filters

Abstract This research was focused on developing a non-steady-state numerical model to differentiate the adsorption and biodegradation quantities of a biological activated carbon (BAC) column. The mechanisms considered in this model included adsorption, biodegradation, convection and diffusion. Simulations were performed to evaluate the effects of some parameters such as specific biodegradation rates and diffusivities on adsorption and biodegradation performances for the removal of dissolved organic matter from water. The results show that the developed model can predict the experimental data well. The biofilm developed around the BAC granules can hinder the mass transfer of the substrate onto the GAC surface, and the adsorption process will be restricted by the biofilm thickness. Although increasing the specific biodegradation rate can increase the performance of biodegradation, the adsorption efficiency will be decreased by lowering the boundary concentration in the interface of GAC. On the contrary, increasing the diffusivity can increase both the adsorption and biodegradation efficiencies simultaneously; so that the overall removal efficiency can be promoted through the improvement of mass transfer.