Remoção de sulfetos e obtenção de enxofre elementar em reatores UASB com adição de oxidantes

Abstract

In the treatment of sanitary sewage in UASB reactors anaerobic digestion occurs, among the several processes that comprise it, sulfide produces sulfide, which causes several problems, such as: odor emanation, corrosion, toxicity and decrease of methane concentration in the Biogas. This research aims to improve processes to produce elemental sulfur and reduce the concentration of sulfides in the effluent and biogas of UASB reactors with the addition of oxidants in the treatment of sanitary sewage. The experimental investigation was divided into three phases. In the first one, three reactors were used, two microaerobes and a UASB reactor with addition of nitrate to the tributary. In the second phase, a microaerobic reactor and a UASB reactor with nitrate addition were operated. In the third phase two reactors were operated, one microaerobic and one UASB reactor (control). When analyzing the results of the reactor monitoring, it was possible to identify that the first-stage microaerobic reactors with sulfide removal efficiencies higher than 90%. And an elemental sulfur production of approximately 28% in relation to the total affluent sulfur. In the second phase the reactors also removed more than 90% of the total dissolved sulfide, but with respect to the elemental sulfur, the production had less expressive results. The nitrate addition reactors showed 98% of the sulphide removal 2- -1 efficiencies, with a mean concentration of 0.2 ± 0.06 mg S-S . L . In the third phase the microaeration provided a sulfide removal of 84% in the effluent and 97% in the biogas, with an average of 8 ppm. Then there was a reduction in the emanation of odors and several other problems related to high concentrations of sulphide in the effluent and in the biogas of UASB reactors.