Uso da clarificação convencional como alternativa para o pós-tratamento de efluente de Reator UASB

Abstract

The need to produce quality effluents is growing, whether for disposal in water bodies or for urban, agricultural or industrial reuse. In Brazil, the discharge of effluents follows the standards established by the National Environment Council through CONAMA Resolution Nº. 430/2011. A low cost technology for the treatment of sewage is the UASB reactor, which is efficient in removing organic matter, however its effluent does not meet the discharge standards, therefore requiring post-treatment to improve and adapt the system final effluent. Among the post-treatment options, this study studied conventional clarification, composed of three unit operations, namely: coagulation, flocculation and sedimentation, using aluminum polychloride (PAC) as a coagulant. The clarification aims to remove total suspended solids, turbidity, COD, phosphorus and sulfide. In search of the best coagulation / flocculation conditions, two factorial designs with three centralpoints were used as a way to find the best answers for phosphorus removal, COD (Chemical Oxygen Demand), SST (Total Suspended Solids), turbidity and sulfide, and thus apply this data on a pilot scale. Therefore, a station was operated, with a treatment capacity of approximately 1m³ / day of UASB reactor effluent. On a bench scale, it was possible to obtain a removal above 90% of total phosphorus and turbidity, 60% of COD removal, 90% of sulfide and 55% of SST. Finally, a full-scale system was monitored, which had a UASB reactor and clarification as one of its stages. Applying the results of the bench on the pilot scale, we found very close and very efficient results, so it can be applied on a larger scale, however it is not yet ready for launch or reuse, with the need to implement an intermediate treatment between systems.