Análise do impacto do esgotamento sanitário na qualidade da água de rios através de modelagem computacional – estudo de caso no rio Piabanha/RJ

Abstract

The growing demand for water coupled with the recurrent degradation of water bodies due to pollution increases the need for new sources of raw water. The lack of sanitation is a factor that negatively affects the environment, public health, tourism, economy and social welfare. Hence, the present study analyzes the impact of the universalization of sanitary sewage services and the implementation of wastewater reuse on the water quality of rivers. An analysis was performed through computational water quality modeling, using the QUALUFMG tool, in an experimental watershed, the Piabanha river basin, in Rio de Janeiro. Three scenarios were simulated, the Present, with current disposal and withdraw conditions in the watershed; the Universalization in which all wastewater was collected and treated before discharge and; the Reuse scenario where, after universalization, 30% of the effluents were sent, through reuse practices, to other destinations other than discharge into the body's water receptor. Besides Petropolis is the city with the best sanitation infrastructure in the watershed, the high disposal of organic matter was diagnosed in the headwaters, the city’s urban region, where the river's dilution capacity is low. Scenarios simulations showed a progressive improvement over the simulations measured by decrease of river segments violating the parameters defined for adjustment classes. The improvement was also measured in terms of mean DBO (reduction) and OD (increase) concentration rates. In conclusion, reuse acts an efficient water resource management tool by reducing the pollutants discharge and increasing water supply. Finally, it should be highlighted the difficulty to obtain official public data and inconsistencies between official data sources.