Contribuição ao estudo e modelagem matemática de reator anaeróbio de leito granular expandido (EGSB) tratando água residuária de suinocultura

Abstract

Anaerobic systems have been widely studied and used in treatment of wastewater from agriculture and others. Among the existing technologies, there are the EGSB (Expanded Granular Sludge Bed) reactors, which have emerged as improvement of UASB (Upflow Anaerobic Sludge Blanket) reactors. It was sought to evaluate the performance of an EGSB reactor using synthetic swine wastewater as substrate, increasing the volumetric organic load (2, 4, 8, 10 and 15 kgCOD.m-3.d-1) and the upflow velocity (6 and 10 m.h-1). Efficiencies higher than 83% were obtained in removal of COD, however there was a buildup of volatile acids and a possible microbial imbalance after the application of the load 10 kgDQO.m-3.d-1. The reactor showed homogeneity in microorganisms along the reactor, with the presence of bacilli of different sizes, coccus, and similar to the genera Methanosaeta and Methanosarcina. It was developed a mathematical model aiming to study in more detail the hydrodynamics of EGSB, generally regarded as continuous complete mix reactors (CSTR). For that, it was used a phenomenological model based on the mass balance of the reactor, and after the adjustment to the experimental data, it was observed that the EGSB reactor can be worked as a series of five continuous complete mix reactors (CSTR), three in the tube region and two in the separator region with kinetic intrinsic rate at approximately 7,5.10-5 L.mgSSV-1.h-1 and kinetic rate constant decreasing with increase in organic load.