Contribuição da presença de sulfatos e sulfetos para corrosão em esgotos sanitários tratados por lagoas de estabilização

Abstract

Biological treatment of sanitary effluents, despite needing large areas to be implanted, is quite advantageous because it is simpler, less expensive and uses natural, biological mechanisms. Due to the various chemical species present in the effluents, such as sulphates (SO42-) and sulfides (S2-), and some microorganisms that producing acids, the medium becomes favorable to the wear and tear of concrete structures of sewerage due to corrosion. that starts. Thus, the present work aims to evaluate how sulfates and sulfides present in sanitary effluents treated by stabilization ponds located in ten municipalities of the state of Ceará can contribute to the corrosion of the concrete pipes of the systems, as well as to evaluate the quality of treated effluents. for launching purposes in accordance with the standards required by Resolution No. 02 of February 2, 2017 of the State Environmental Council (COEMA). Thus, the samples were collected and selected for analysis the following physicochemical parameters: sulfate (SO42-), sulfide (S2-), dissolved oxygen (DO), pH (at 25 °C) and conductivity (at 25 °C), besides the microbiological parameters: total and thermotolerant coliforms. It was found that all results were within the required resolution parameters and, therefore, it can be said that the treatments were effective and all effluents are able to be released into a recipient body. In addition, it was observed that the analyzed effluents are within the class of weak aggressiveness to concrete structures, since they had contents below 150 ppm SO42-.