Análise das características hidrodinâmicas hidráulicas em reatores do tipo UASB verificando influência da biomassa no regime de escoamento

Abstract

The course conclusion paper aims to analyze the hydrodynamic behavior and the hydraulic characteristics of UASB reactors operated under different conditions in the treatment of synthetic wastewater, as well as analyze the influence of biomass in the reactor flow regime through statistical analysis. Thus, were used two UASB reactors in bench scale made of plexiglass with a volume of 1 L and operated with a flow rate of approximately 4 L.d-1 (0.166 L.h-1) and theoretical HRT of 6 h. The abiotic reactor was fed with water and operated in two stages: Stage I without simulation of the generation of biogas; a Step II with simulation of the generation of biogas and biotic reactor (R2), which corresponds to step III was filled with granular anaerobic sludge from a RALF reactor of the ETE of the Umuarama city and continuously fed with a synthetic effluent. The assays was performed at 30 minutes intervals with a total duration of 18 hours in each assays. It was used eosin Y, bromophenol blue and bromocresol green as tracers. The real HRT values obtained ranged from 3.8 to 7.4 h, and approximately 63% of the values were lower the theoretical HDT probably due to the absence of obstacles along reactor, the movement of biogas bubbles that pushed up the tracer, the occurrence of preferential paths, short-circuits and even probable occurrence of dead volumes in the reactor. As for the N- CSTR values were found 1 to 4 complete mixing reactors in series. By analyzing the RTD curves and correlation coefficients, it was observed that the uniparam é tric model of complete mixing tanks in series (N-CSTR) presented best fit the experimental data obtained. The low dispersion model (LD) showed best fit to the experimental data, although initially the trials did not respect their premisses. The analysis of the hydraulic characteristics relative the volume of dead zones in Step I showed greater volumes of dead zones for the tests with bromophenol blue (approximately 13%, 18% and 0%, respectively), in Step II and III the greater volume of dead zones were found in tests with bromocresol green, with values of around 33%, 18% and 23% respectively for Step II and approximately 13%, 12% and 37% in Step III. Compared to hydraulic short circuits there was a higher occurrence in Step II with values of about 0.09 in all tests with eosin Y, 0.25 in the assays 3 with blue bromophenol and 0.28 in the assays 1 with bromocresol green. Among the tracers used bromophenol blue showed the best fit curves for DTR Steps I and II, while for Step III was bromocresol green.