SMART-Plant_Dynamics of GHG emissions from a typical full-scale WWTP in Italy

5th International Conference on Sustainable Solid Waste Management Abstract: Purpose The current work presents the results of a long-term online N2O monitoring campaign in an Italian wastewater treatment plant (WWTP) that applies conventional activated sludge process. The aim of this study is to examine the effect of different gaseous sampling methods on the profile of N2O emissions in a full-scale WWTP. Methods The effect of operational parameters of the secondary treatment on the generation of N2O emissions is investigated through the continuous monitoring of N2O, NO and NO2 emissions in the nitrification reactor. Statistical and event-driven sensitivity analysis based on cause-effect relationships was applied to evaluate potential relationships between the online monitored parameters and the N2O emissions. Two different types of gas chambers were examined; fixed and floating. Results The average N2O emission factor (EF) was 0.001% and 0.005% of TN in the influent for the fixed and floating chambers respectively. The diurnal variation of N2O emissions varied significantly for the different gas chambers. The results indicated that the rate of N2O emissions was partly affected by the different gas chambers; however, a COD:TN ratio lower than 4:1 systematically resulted in higher N2O emissions. The sensitivity analysis showed that the N2O dynamics are not significantly affected by dissolved oxygen (DO) variations (within the range of 1.5 – 2 mg/L). Conclusions The effect of the application of different gas chambers on the N2O profiles demonstrated the significant role of the sampling protocol within the full-scale N2O monitoring campaigns. In the current study, N2O emissions were mainly affected by the ammonia loading rate in the reactor. Keywords: Nitrous oxide emissions, Full-scale monitoring, Activated sludge, event based sensitivity analysis; gas sampling assessmen