Prolonged lifetime of biological activated carbon filters through enhanced biodegradation of melamine

Micropollutants can be removed in Biological Activated Carbon (BAC) filters through biodegradation, besides adsorption, when the conditions are favorable. In the present study, we build upon previous work on melamine biodegradation and activated carbon regeneration in batch experiments and assess the efficiency of this process in continuous flow lab-scale BAC filters. Melamine is frequently detected at low concentrations in surface water and is used here as a model micropollutant. BAC filters were inoculated with melamine degrading biomass and the contribution of biodegradation to melamine removal was assessed. Furthermore, we tested the effect of an additional carbon source (methanol) and the effect of contact time on melamine removal efficiency. We demonstrate that inoculation of activated carbon filters with melamine degrading biomass increases melamine removal efficiency by at least 25%. When an additional carbon source (methanol) is supplied, melamine removal is almost complete (up to 99%). Finally, through a nitrogen mass balance, we demonstrate that around 60% of the previously adsorbed melamine desorbs from the BAC surface when biodegradation rates in the liquid phase increase. Melamine desorption resulted in a partial recovery of the adsorption capacity.