Tratamento de esgoto doméstico em reator anaeróbio-aeróbio de leito fixo com recirculação da fase líquida

Abstract

This completion of course work aimed to evaluate the performance of an anaerobic-aerobic fixed bed with and without recirculation of the liquid phase, the reactor immobilized with polyurethane foams and expanded clay, used in the treatment of sewage. For this, a bench scale reactor (4,75 L) was operated with influent flow rate of 0.6 L h-1 and HRT of 8 h and kept at room temperature. We evaluated the following physico-chemical parameters: temperature, pH, total alkalinity, and partial baking, volatile acids, COD (raw and filtered), total solids (fixed and volatile) and suspended solids (fixed and volatile), were also carried series of nitrogen (total Kjeldahl nitrogen, ammonia nitrogen, organic nitrogen, nitrite and nitrate). In addition, tests were performed stimulus-response type wrist with eosin Y in order to know the hydrodynamic flow reactor and verify the presence of anomalies in the hydrodynamic behavior. The results of characterization of sewage classified as "strong" in terms of COD and total solids. The microscopic examinations were performed during the inoculation to evaluate the microbial flora in the reactor. Among the bacteria, the morphologies were observed most cocos, vibrios, bacilli and filaments. The system performance was evaluated in two different conditions, with the same hydraulic retention time (HRT), 8 hours. One without recirculation and another with the inclusion of the recirculation of the liquid phase. The condition without recirculation showed high removal efficiency of organic matter in terms of COD (86%), and removing solid (63%). The combined system is shown quite stable, even with variations in organic loads imposed on the system. The nitrite concentrations are always kept low, which indicates balance nitrification. Gains made were obtained when recirculation of the treated effluent, especially in relation to the removal of organic matter removal reached 99% and total nitrogen removal was 71% for recirculation ratio of 0.5. The reactor had rated operational stability, high removal of organic matter and nitrogen without the need for addition of exogenous carbon source and alkalinity supplementation.