Development of an Extended ASM 3 Model for Predicting the Nitrous Oxide Emissions in a Full-Scale Wastewater Treatment Plant

3 An Activated Sludge Model #3 (ASM3)-based, pseudo-mechanistic model describing nitrous 4 oxide (N2O) production was created in this study to provide more insight into the dynamics of N2O 5 production, consumption, and emissions at a full-scale wastewater treatment plant (WWTP). N2O 6 emissions at the studied WWTP are monitored throughout the plant with an FT-IR analyzer, while 7 the developed model encountered N2O production in the biological reactors via both ammonia 8 oxidizing bacteria (AOB) nitrification and heterotrophic denitrifiers. Additionally, the stripping of 9 N2O was included by applying a KLa-based approach that has not been widely used before. The 10 objective was to extend the existing ASM3-based model of the plant and assess how well the full11 scale emissions could be predicted with the selected model. The validity and applicability of the 12 model were tested by comparing the simulation results with the comprehensive online data. The 13 results show that the ASM3-based model can be successfully extended and applied to modelling 14 N2O production and emissions at a full-scale WWTP. These results demonstrate that the biological 15 reactor can explain most of the N2O emissions at the plant, but a significant proportion of the 16 liquid-phase N2O is further transferred during the process. 17