Irradiação de micro-ondas e air stripping em sistema contínuo para remoção de amônia de água residuária

Abstract

In this final project, it was investigated the removal of N-ammonia by combining microwave and air stripping in a continuous system. It was evaluated the influence of the initial pH (9 to 12), the liquid’s flow (60 to 100 mL.min-1) and the initial concentration of N-NH3 (1 to 5 gL-1) through statistical planning Composite Design of Rotational Central (CDRC), totalizing 20 trials. The power of microwave irradiation was maintained at 100% (555 W) and the airflow 0.95 m3.min-1. With the analysis of ammoniac N of both initial and final samples of the process, it was possible to calculate the removal percentage. The main results indicate that the linear term of the independent variable pH has greater significance with 5% level, followed by the quadratic term pH, linear term of initial concentration of nitrogen and, the last one, the linear term of the pump flow, being the others not considered significant. The microwave effect in the system was less significant if compared to the pH, since the pump flow rate is related to the retention time of the influent in the apparatus. The low significance of the independent variable pump flow may have been experienced by the short amount of flow range. With these pump flows at the exit of the wastewater microwave oven, water reached a temperature range of 77 to 64°C, with only 13ºC difference. The maximum removal percentage of ammonia in this continuous system was 81.1%, indicating the combination potential of microwave irradiation and air stripping tower in the performance of a continuously operated system.