This work presents a short and long-term calibrated 1D-model for the MBBR process operated under nitrogen removal conditions. Experimental data have been collected at a pilot-scale MBBR fed with a municipal wastewater. Several protocols have been applied to determine the variations versus time of the mass and the maximal thickness of biofilm, the limit liquid layer thickness, the maximal nitrification rate and the oxygen mass transfer coefficient in sludge. The MBBR system operation has been followed-up for 4 days under dynamic conditions for short-term calibration, and for 33 days under steady-state for long-term calibration of the model. Compared to the short-term calibrated parameters set, the maximal biofilm thickness, the limit liquid layer thickness and the oxygen mass transfer coefficient in sludge have been adjusted to the new conditions of the 33 days long-term period. After calibration, a good fit between measured and simulated data has been reached during short and long-term period, particularly for nitrogen forms. Then, the calibrated MBBR model has been used to predict the MBBR functioning under other conditions.