Effect of air flow, intermittent aeration time and recirculation ratio in the hydrodynamic behavior of a structured bed reactor

摘要

Among the novel system configurations that remove organic matter and nitrogen simultaneously, the structured bed reactor with recirculation and intermittent aeration (SBRRIA) can be mentioned. Studies addressing the SBRRIA have shown high efficiency of organic matter and nitrogen removal, as well as low sludge production. However, operational parameters such as the recirculation rate, intermittent aeration time, and airflow are not fully established. Therefore, this research aimed to evaluate the effect of these three parameters on the mixing characteristics of an SBRRIA adopting established hydrodynamic models, also proposing a new flow model for the reactor. Hydrodynamic tests were performed using sodium chloride as a tracer, and the variables were the recirculation rate, intermittent aeration time, and airflow. Results showed that the reactor presented a plug-flow behavior when the aeration was turned off and behaved as a completely stirred reactor when the aeration was turned on. Traditional models were not sufficient to explain the flow of the SBRRIA, resulting in the development of a simplified programming pseudo-code to adequately represent the flow in the reactor. The tested airflow and recirculation rates did not affect the mixing behavior in the SBRRIA. These observations represent a significant advance in SBRRIA studies as they show that energy consumption could be optimized, making the system even more advantageous by saving electrical energy up to 75% due to pumping.