ABSTRACT: Biological processes are being applied to nitrogen removal from wastewater. The conventional process is based on nitrification followed by denitrification. In nitrification process the ammoniacal nitrogen is oxidized to nitrate and it is strongly influenced by availability of dissolved oxygen. In this context, kinetics studies are an alternative used to evaluate the microorganisms activity by defining substrate (NH3-N) consumption and the influence of others parameters, like oxygen and substrate. The present study aims to evaluate the ammonium consumption rate by nitrification process at three different ammonia concentrations (100, 200 and 300 mg NH3-N L -1 ) at air flow rates of 20, 30, 50, 100, 200 and 500 mLair min−1 L −1 reactor. The kinetics were made by batch tests in an EGSB reactor at temperature of 25ºC for 2h30min. It was visualized that with 100 and 200 mg N-NH3 L - ¹ the substrate concentration was fully consumed. However, at the substrate concentration of 300 mg NH3-N L - ¹ an increase of substrate consumption was observed but ammonia was not entirely consumed. Furthermore, for the three initial ammonia concentrations, the behavior of substrate consumption was similar in function of air flow rate. Additionally, it was possible to conclude that as the supply of oxygen increased, the nitrogen ammoniacal consumption rate also increased
