Abstract Wastewater systems are high-energy consuming processes that discharge considerable amounts of pollutants into aquatic ecosystems, thus requiring appropriate optimization. Therefore, a full-scale activated sludge process was studied in this work through mathematical modeling of heterotrophic and nitrifying microorganisms. The airflow rate was introduced as the controlling parameter to accomplish the degradation of pollutants. Moreover, a sensitivity analysis was performed to determine the most sensible parameters that should be evaluated through further experiments, aiming to improve the model. The obtained results indicated that readily biological oxygen demand degradation and the oxidation of ammonia to nitrite could be achieved with an airflow rate of 35 m 3 air d -1 . The sensitivity analysis showed that heterotrophic kinetic parameters and oxygen mass transfer coefficient through diffusers are the most sensitive to the system. These results also proved that the air-diffusing systems can work at 0.3% of their maximum capacity to accomplish degradation. Future studies should consider other oxygen-consuming variables.