Garantia probabilística em monitoramento da qualidade de efluente de um sistema de lagoas de estabilização

Abstract

The uncontrolled discharge of effluents into the environment causes water pollution. The excess of organic matter causes the depletion of oxygen in the water and kills the living beings dependent on it. Another problem with sewage is the possibility of contamination by disease-causing microbial agents. The adequate application of instruments and techniques aimed at controlling water pollution requires material guarantee over time. It also demands full understanding of the corresponding legislation and its consequent understanding and compliance. In addition, it is necessary to have analytical resources to assess the performance of sewage treatment plants. Thus, the computation of the reliability of an sewage treatment plants considers the quality of the treated effluent and the compliance with pre-established normative limits as the study has as its general objective to determine the degree of probabilistic guarantee in meeting the environmental standards. This theme deals with the discharge of effluent from a full-scale stabilization pond system. To achieve the objectives, the following analytical parameters of the effluent quality of the Ponta Negra lagoon system were considered: biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonia (AMN), pH, temperature (temp.) and thermotolerant coliforms. In all, 25 samples were collected from January 2014 to November 2017, referring to raw sewage and treated sewage, effluent from the last maturation pond.