Desempenho do sistema UASB-LGA operando no tratamento de água residuária da suinocultura: o que o sistema pode oferecer em termos de água de reúso

Abstract

Pig farming is an agricultural activity of great economic and social importance, as it is mainly responsible for the protein consumed worldwide. However, its production process generates an effluent with a high polluting potential, known as Swine Wastewater (SWW). Thus, this work aimed to evaluate the performance of a system consisting of an Upflow Anaerobic Sludge Blanket (UASB) reactor followed by an Aerobic Granular Sludge (AGS) in the treatment of SWW, on the removal of organic matter and nutrients in order to promote the reuse of the treated effluent. For this, the system was monitored for 90 days, characterizing the experiment Phase I. The UASB reactor was fed with SWW with a COD concentration of 5 g L-1 and its startup took place under organic load conditions, with application of a Volumetric Organic Load (VOL) of 10 kg COD m3 d -1 , Hydraulic Loading Rate (HLR) of 1.10 m3 m-3 d -1 , Hydraulic Retention Time (HRT) of 12 ascending velocity (VA) of 0.14 m h-1 , being fed with SWW with a COD of 5 g L -1 . The influent values of COD, Q, VOL, HLR and HRT were constant during the experiment. After treatment, the AGS reactor was operated with a 50% volumetric exchange and a 12-hour cycle time. The average removal efficiencies of Total Chemical Oxygen Demand (DQOT) and Biochemical Oxygen Demand (BOD5 20 °C) from the system were 91.3 and 93.2%, respectively. The removal efficiencies of Total Suspended Solids (TSS), Volatile Suspended Solids (VSS), Ammoniacal Nitrogen (NAm) and Total Phosphorus (P) were 89.5, 87.5, 86 and 75%, respectively. It was concluded that the system showed stability throughout the experiment, and high levels of organic matter and nutrients removals. However, given the high polluting load of SWW, the parameters did not reach the limits defined in current legislation for reuse. Thus, it is essential to develop a better structured regulatory document, as well as the adoption of a tertiary treatment or final polishing, such as constructed wetlands, to enhance the organic matter and nutrients removals, and enabling the achievement of quality for reuse application.