Study on dissolved organic nitrogen (DON) removal by activated carbon adsorption

Dissolved organic nitrogen (DON) is an important issue in drinking water field. This paper deals with DON removal by activated carbon (AC) in batch and fixed bed operation. Adsorption kinetics and equilibrium isotherms in batch operation are investigated while the breakthrough curves in fixed bed operation for DON adsorption at different conditions are obtained. The isotherm results show that the peach carbon is the most suitable type which shows higher adsorption capacity than other ACs. Kinetic data of adsorption are well fitted by the pseudo-second-order kinetic model, and the thermodynamic constants are also evaluated in the study. The results of the fixed bed operation show that, with the increase of the flow rate and the influent concentrations, the breakthrough curve becomes steeper while the break point time decrease. With the increase in the bed height, the breakthrough time increases. Adams-Bohart model is used to describe the initial region of breakthrough curve, while bed depth service time model is applied to predict the breakthrough time for new conditions. Both models give good agreement with experimental curves. This paper reveals the suitable ACs for DON removal and gives the basic data for DON removal in fix bed adsorption.