Developing the mathematical model to predict the nitrogen removal and N2O emission by the biological aerated filter

Abstract

Despite the established evidence that the influent Carbon/nitrogen (C/N) ratio affects nitrogen removal properties and nitrous oxide (N2O) emissions in the biological aerated filter (BAF), N2O production is difficult to predict when influent C/N ratios fluctuate widely for actual wastewater treatment systems. In this study, a simplified mathematical model was developed and applied to the BAF system. The operational parameters that influenced the effluent quality and N2O emissions were optimized by sensitivity analysis. Using an experimental dataset with C/N ratio of 5, model parameters were developed for predicting N2O emissions. Subsequently, the model was extended to predict N2O concentrations over a larger range (i.e., C/N 2 and 8), and comparisons were performed to verify its applicability. Results from this study indicated that YNO2,HB was the most sensitive stoichiometric coefficient for predicting N2O emissions (sensitivity = 15.5 %), and that the developed model could accurately predict nitrogen removal and N2O emissions over a C/N ratio range of 2 to 8 in BAF. The proposed mathematical model could benefit the estimation of GHG emissions from full-scale wastewater treatment plants and thereby contribute to improving the friendly operation of BAF treatment facilities.