Utilização de esgoto sanitário tratado em lagoa de estabilização para produção de pasta de cimento e concreto

Abstract

In face of the growing scarcity of potable water it is of major importance the searching for new alternative sources of water, mainly for sectors of high consumption like civil construction. Thus, this research disposes to analyze the technical viability of the use of domestic sewage treated by stabilization ponds at the Sewage Treatment Station of Mangabeira, operated by CAGEPA (Companhia de Água e Esgotos da Paraíba), located in João Pessoa - PB as kneading and concrete cure water. Initially it was estabilished a 25 MPa resistance for the produced concrete, and thus with the description of the aggregate the dosage was done. Subsequently, the effluent was collected in different periods, for a better specification of the treated sewage, totaling four samples on which chemical analyzes were carried out indicated by Mercosur Standard 137. The results obtained in the tests of determination of the pH at 25 ° C, total iron, total solids, chlorides and soluble sulfates were coherent to the required limits and thus the production of the concrete was possible. With the effluent samples, 48 concrete cylinders were produced and for comparison purposes, 16 concrete cylinders with water supplied by CAGEPA, totaling 64 elements. After the moldings and due cures, the compressive resistance for age of 7, 28 and 120 days, as well as the modulus of elasticity were analyzed. Finally, the results of the resistance for 7 days, presented values divergent to the tolerance exposed by the norm under study. On the other hand, at 28 days, it was observed that the resistance had an increase of 54,29%, a result that was within the limits required by norms NM 137 and for ages of 120 days, the concrete produced with effluent presented 24,92% more resistant to potable water. While the modulus of elasticity showed no variability between the mean values of fck established by the destructive and non-destructive method, confirming the consistency of the values found in the compression test, it was also verified that the effluent did not interfere considerably in the fck of the concrete produced. Therefore, the sewage treated in the study, met most of the requirements discriminated by the Mercosur Standard 137, proving suitable for the production of cement paste and concrete.