Influência da estiagem prolongada na qualidade de água tratada – avaliação com número fuzzy triangular na bacia do Banabuiú

Abstract

Drought phenomena reduce water availability and affect the quality of water sources. These consequences bring great difficulties for the concessionaires to provide water within the quality standards required by ordinance MS Nº 2914 of 2011. Drought periods also accentuate the concentration of pollutants in reservoirs by accelerating the eutrophication process and substantially affecting water treatment due to the increased need for color removal and turbidity. Considering this scenario, the reliability analysis of the treatment of water stations acquires significant importance. The reliability of a system is obtained through a monitoring capable of evaluating the probability of it obtaining no failure in its operation in a certain period of time. In this context, the Fuzzy Agreement Index method emerges as a viable model capable of dealing with uncertainties and studying the assurance of water supply systems. The present work analyzes the effects of seasonality and cyclical periods on quality assurance in water treatment plants, verifying the influence of the rainy season and the dry season on four physical parameters: pH, apparent color, turbidity and free residual chlorine. Six stations were part of the study, three of direct ascending filtration and three of full cycle. The study was carried out using the average data from 01/01/2007 to 06/30/2017, in daily tests carried out in the ETA laboratories. From the obtained results, a performance reduction was observed in the parameters of color and turbidity in the rainy periods and in the drought years, obtaining considerable variations, mainly in turbidity. The methodology is a solid alternative in assessing the quality assurance of water treatment, providing better control of operational processes.