Análise de sistemas piloto composto por reator UASB seguido por lodo ativado com decantação intermediária

Abstract

The Brazilian northeast has a great potential - which needs to be further explored - thanks to its hot climate, which is favorable to the biological sewage treatment. A biological method that has been commonly used in large Sewage Treatment Plants (STP) uses UASB reactors followed by an activated sludge system, justified mainly by the reduction of STP costs, the low area requirement and the high quality of its effluent. However, this configuration can present certain problems due to the reception of the aerobic sludge in the UASB reactor in order to stabilize it, for example, the expulsion of the sludge from the anaerobic reactor for the following steps. With a view to analyzing a solution to the aforementioned problems, the monitoring and characterization of two pilot systems composed of a UASB reactor and activated sludge system was carried out, one of them with an intermediate decanter, both receiving a flow of 100 L/day of domestic sewage. The monitoring was divided into two stages: stage 1 followed the stabilization of systems without recirculation of aerobic sludge disposal to the UASB, while stage 2 referred to the system in full operation with sludge recirculation. Both systems performed satisfactorily, obtaining COD removal efficiencies of 75% and 69% in phase 1 and 68% and 70% in phase 2. Notably, the anaerobic treatment stood out in terms of organic matter removal, and low concentration of solids in the effluents, close to 20 mg/L in both reactors and for both phases of monitoring. Although the system had a good initial performance, it was not possible to determine the real influence of the intermediate decanter, requiring more monitoring time of. In this way, it is suggested that more work be carried out in this line of research, which is still poorly elucidated.