Composição e variação espaço-temporal das características dos esgotos sanitários em Maceió-AL

Abstract

The considerations of the quantitative and qualitative aspects of sanitary sewage by means of physical-chemical and microbiological analyses are of extreme importance to ensure the operation of sanitary sewage systems within the foreseen standards. It happens that the sewage network coverage in Brazilian cities is still partial, and there are places that use individual solutions or simply throw their sewage in the street beds or urban channels, turning them into unitary systems, where the sewage is carried mixed with rainwater, runoff from the spring itself and other residues. The city of Maceió/AL is developed by a low region where the lagoon and maritime coastal plain is located and a high region in the tablelands, and its coverage by sewage collection system is still in expansion, currently reaching about 40% of the population, and thus, its urban channels receive diffuse contributions of sanitary sewage throughout its course. In this context, the aim of this work was to monitor through qualitative, spatial and temporal characterization, the collecting network and urban channels of Maceió. For this purpose, biweekly collections of simple samples of raw sewage were performed in the main urban drainage channels of the city, in the sewage collection network and in the WWTP of a public hospital, during the period from December 2021 to June 2022, in order to analyze the spatial and temporal composition of the physicochemical and biological characteristics of the sewage, considering the dry and rainy periods, and the socioeconomic characteristics of the study area. The results showed that the sewage from the upper part of the city, which arrive at the ETEs, where a low-income population predominates, present constituent values typical of high concentration sewage, while those from the lower part of the city, where a high-income population predominates, present a composition typical of medium-concentration sewage, inversely to what is mentioned in the literature, since the lower part is a coastal region where the influence of the water table diluting the sewage is more significant than the contribution of rainwater in the network. It was also verified that hospital wastewater presents typical characteristics of high concentration wastewater and that the water quality of urban channels classifies it as low concentration sanitary wastewater.