Garantia de qualidade de efluente de lagoa de estabilização: avaliação com simulação Monte Carlo e número Fuzzy triangular

Abstract

Monitoring the performance of sewage treatment plants (STP) is critical to ensuring the environmental quality of water bodies and the maintenance of human health. The release of effluents into water bodies must meet the limits set by the discharge standards. In what regards STP, the concept of guarantee is related to the percentage of time in which the effluent concentrations meet the discharge standards. This study aims to calculate the guarantee for the quality of sewage treatment systems using Monte Carlo simulation and Fuzzy Numbers. It was analyzed 10 stabilization ponds systems located in the state of Rio Grande do Norte. The guarantees of the systems were calculated for the parameters BOD, filtered BOD and Ammonia Nitrogen. The obtained results of guarantee were submitted to a correlation analysis to check its consistency. Were also evaluated the correlation between the guarantee values and the volumetric application rates and the superficial application rates of each system. At the end of the analysis it could be concluded that the results obtained by the different methodologies were consistent and indicate a low guarantee compliance with the standard limits for BOD and filtered BOD parameters as well as a low correlation of guarantee values for these parameters and volumetric and superficial application rates. Although, the Ammonia Nitrogen parameter presented better compliance with the standard limits and a moderate correlation between guarantee values and superficial application rate. Regarding the methodology evaluation, both methods were considered simple although the methodology that makes use of fuzzy numbers was considered more robust as it enables time economy and requires less operational effort