Análise de parâmetros hidrodinâmicos de reator anaeróbio-aeróbio de leito fixo com biomassa imobilizada

Abstract

The aim of this study was evaluate the hydrodynamic behavior of anaerobic-aerobic packed-bed reactor, operated with hydraulic retention time (h) of 18h and 12h, with immobilized biomass, treating raw wastewater of bovine slaughterhouse. As a support to biomass immobilization, it was used matrices polyurethane under a rigid structure polypropylene in Reactor 1 (R1) and Luffa cilyndrica (cellulose sponge) in Reactor 2 (R2).The reactors were operated on bench scale with a useful volume of 4.75 L and 4.3 L to R1 and R2 respectively, have been kept at room temperature. To evaluate the hydrodynamic behavior and possible flow anomalies were carried out stimulus-response assays, pulse type, using eosin Y as tracer. In order to assess the state of apparent dynamic balance of the reactors during their operation, It were monitored the physical and chemical parameters such as pH, temperature, dissolved oxygen, bicarbonate alkalinity, volatile acids, COD (crude and filtered), total solids and total solids suspended solids. The results were satisfactory regarding to organic matter removal efficiency to R1 and R2 operated with h 12 h, averaging of 68 and 76% crude and filtered COD respectively for R1, and 57 and 63% for R2.In operating the reactors with h 18 h, the efficiencies dropped to 49 and 60% crude and filtered COD respectively for R1, and 52 and 51% for R2.Even with the drop in efficiency, the reactors proved to be robust to withstand loads shock when operated with hydraulic load variation imposed. At the results of hydrodynamic assays was observed the phenomenon of the long tail in the concentration curve of tracer eosin Y and delay its response at the output of treated effluent. It was also found that the flow pattern approached to the complete mixing for the two reactors and that the h of 12 h proved better hydrodynamic behavior of reactors and greater capacity to withstand hydraulic load variations. In the tests it was checked the presence of short-circuits and dead zones in the reactors, with 11% and 7% dead volume in R1 and R2 respectively, to hof 18 h and 20% for both with hof 12 h. The hydraulic efficiency of the reactors was classified as poor and the values of Reynolds number indicated laminar flow regime. The support media at R1 provided RTD curves with higher D/uL values, suggesting high longitudinal dispersion and faster mixing within the reactor.