Comportamento de reator anaeróbio-aeróbio no tratamento de efluente bovino

• Autor(a) principal: Kreutz, Cristiane
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do UNIOESTE
• Texto Completo: http://tede.unioeste.br:8080/tede/handle/tede/2884
• topic: processo combinado; reator de leito fixo; comportamento hidrodinâmico; eosina, traçador; tempo de detenção hidráulico; combined process; fixed bed reactor; hydrodynamic behavior; eosin; tracer; hydraulic detention time; CNPQ::CIENCIAS AGRARIAS::ENGENHARIA AGRICOLA

In this study, it was evaluated the operational conditions, the organic matter, nitrogen and phosphorus removal efficiency and the hydrodynamic behavior of a continuously up-flow combined anaerobic-aerobic fixed bed reactor (RAALF), operated in bench-scale, filled with expanded clay and polyurethane foam cubic arrays as means of biomass immobilization support, in the treatment of raw effluent from a cattle slaughterhouse. Three different operational conditions were tested: Step I, characterized by the operation of RAALF in anaerobic condition; Step II, in combined condition (anaerobic-aerobic), and Step III, in combined condition with recirculation. In each operational step three different hydraulic retention times (14, 11 and 8 h) were tested. The hydrodynamics assays were determined using stimulus-response type pulse, with Eosina Y as a tracer to obtain the curves of residence time distribution (RTD). The results from the RAALF in the Step I, under anaerobic condition, indicated that operational conditions ensured the process of anaerobic digestion, with keeping of the pH and the RAALF s buffering, promoting a biochemical balance between acidogenic/acetogenic and methanogenic archaea. In this operational step, the HRT of 11 h showed better result, with removal efficiency of raw COD, filtered COD, TS, TSS and N-amon of 59, 60, 56, 76 and 16%, respectively. In Step II, the HRT of 14 h showed better results in terms of organic matter and solids removal efficiency, with 58, 66, 66 and 84% for raw COD, filtered COD, TS and TSS, respectively. The overall efficiency of nitrogen removal achieved in this study was 0, 17 and 7% at Step I; 37, 22 and 22% in Step II for the HRT 14, 11 and 8 h, respectively, and 50 and 29% for the HDT of 11 and 8 h in Step III. Therefore, there was an evolution in the overall nitrogen removal efficiency in Steps II and III when compared to Step I, due to the partial nitrification and denitrification. Denitrification has been compromised by factors such as liquid temperature, pH, and DQO/N-NO3- ratio. The efficiency of phosphorus removal was 0, 0 and 15% in Step I and 46, 0 and 0% in Step II for HRT 14, 11 and 8 h, respectively, and 10 and 0 % removal HRT to 11 and 8 h, respectively, in Step III. The ANOVA and Tukey tests indicated that the operational stages I, II and III were statistically different for all physical-chemical parameters evaluated, except for phosphorus, for which it can be stated that the efficiency of organic matter and nitrogen removal was affected by the operating condition. The hydrodynamic study conducted at RAALF indicated behavior tending to a complete mixing and deviations from ideality were found, such as dead zones, recirculation and long tail effect. The dispersion degrees were probably influenced by insertion of the aerobic phase, which improved the liquid mixture inside the reactor. The RAALF presented similar kinetic behavior in the operational steps I, II and III, represented by the first order model, with increase of k and vr parameters along the height of the anaerobic phase and decrease of the kinetic constant and degradation rate in the aerobic phase