N2O emissions from a single-stage partial nitritation/anammox granule-based reactor – a model based assessment

Abstract

Completely autotrophic nitrogen removal (CANR) can be obtained in single stage granule-based bioreactors. However, their environmental footprint is compromised due to elevated N2O emissions. In this study we develop and present results from a novel spatially explicit biochemical process model of granular CANR systems that predicts N2O dynamics and stripping. The model is adapted to predict pH gradients within the granule and considers different granule size distributions and their impact on N2O emissions. The model will serve as a guiding tool to define an operational window, where aeration strategies, granule size and bulk pH are optimized to retain high nitrogen removal whilst minimizing the N2O production