Kinetics of nitrogen removal in pilot-scale internal-loop airlift bio-particle reactor for simultaneous partial nitrification and anaerobic ammonia oxidation

The pilot-scale internal-loop-airlift bio-particle (ILAB) reactor was a novel configuration adopted to study the performance of simultaneous partial nitrification (PN) and anaerobic ammonia oxidation (ANAMMOX). The ILAB reactor was operated at different nitrogen loading rates and hydraulic retention times to investigate the nitrogen removal kinetics. The reactor showed good tolerance to substrate concentration shock while it was significantly affected by hydraulic shock. Five kinetic models including first-order model, Grau second-order model, Stover-Kincannon model, Monod model and Contois model were applied to steady-state experimental data to evaluate the substrate removal in the reactor. The Grau second-order model and Stover-Kincannon model were found to be more appropriate compared with other models to describe and predict the performance of the reactor. Both the models were evaluated by judging the linearity between experimental data and predicted values which confirmed their validity for the process.