Avaliação do comportamento de um reator UASB tratando esgotos sanitários da Universidade Tecnológica Federal do Paraná, câmpus Campo Mourão

Abstract

The objective of completion was to evaluate the hydrodynamic behavior of a UASB reactor operated with constant and subjected to sinusoidal cyclic variation of hydraulic head values in the lower and upper 40% of the inflow of sewage treatment in the Federal Technological University Paraná, campus Campo Mourão. For this, a pilot-scale UASB reactor (160 L) was operated with influent flow of 16 L.h-1 and HRT of 10 h (stage I), sinusoidal cyclic variation in the inflow below and above 40% (stage II) and kept at room temperature. The behavior of the reactor was evaluated by determining the physico-chemical parameters temperature, pH, alkalinity to bicarbonate, volatile acids, COD (raw and filtered), total solids (fixed and volatile) and suspended solids (fixed and volatile). In addition, tests were performed stimulus-response type pulse with eosin Y, bromophenol blue and bromocresol green to evaluate the hydrodynamic regime of the reactor in two stages. The results indicated that the sewage can be classified as "average" in terms of COD and total solids according to Metcalf and Eddy (2003). The average values of pH, bicarbonate alkalinity were 6.8, 128 mgCaCO3.L-1 (step I); 7.2, 247 mgCaCO3.L-1 (step II) for the influent and 7.2, 199 mgCaCO3.L-1 (step I); 7,6, 322 mgCaCO3.L-1 (step II) for the effluent. The average efficiency of COD removal ranged from 51% to 73% (Stage I) and 31 to 79% (stage II). The volatile acid concentration in the effluent resulted in less than 76 mgHac.L-1 (step I) and 106 mgHac.L-1 (step II). The average concentrations of ST were 1138 mg.L-1 and 1022 mg.L-1 (stage I and II) for the influent and 567 mg.L-1 and 622 mg.L-1 (stage I and II) for the effluent. The mean concentrations of TSS 355 mg.L-1 and 323 mg.L-1 (stage I and II) for the influent and 86 mg.L-1 and mg.L-1 (stage I and II) for the effluent. The phenomenon observed in the tail curves obtained results from the diffusion of the tracer in dead zones and its slow release in the effluent. For the Reynolds number was obtained value of 8.7 (step I) and (stage II) was obtained 3.8 to minimum flow (7.10 L.h-1) 5.8 to the average flow (10.66 L.h-1) and 7.7 for maximum throughput (14.20 L.h-1). For the calculation of dead zones was obtained average of 31% and 20% (stage I and II) for assays with Eosin Y, 26% and 30% (stage I and II) for assays with bromophenol blue and 16% and 40% (stage I and II) for assays with bromocresol green. The presence of short circuiting was observed in almost all tests hydrodynamic (step I) and step II was not detected the presence of short circuits. In the study of hydraulic efficiency was found that in all tests have resulted in poor hydraulic efficiency (λ ≤ 0.5) for both constant flow and for the flow variation