An overview of wastewater treatment technologies in Minas Gerais, Brazil: predominance of anaerobic reactors

The deficit in sewage collection and treatment is a problem in Brazil, and a large portion of untreated sewage, usually disposed directly into water bodies, compromises water quality, with implications for public health and environmental balance. This scenario does not differ in the State of Minas Gerais, where only 44% of the urban population has their sewage treated. This study aimed to evaluate the current scenario of the use of wastewater treatment technologies in active wastewater treatment plants (WWTPs) in Minas Gerais, based on a database from the Sewage Atlas, and analyze how the characteristics of the municipality and the treatment system influence the choice of technologies adopted. Information on 376 active WWTPs and 26 WWTPs designed or under construction was obtained. The most commonly used technologies include upflow anaerobic sludge blanket (UASB) reactors, with or without post-treatment, adopted in more than 70% of WWTPs. A logistic regression model was fitted to explain the presence of post-treatment UASB reactors in the municipality. The model showed that the chances of implementing this technology by the municipal autarchy and public companies are, 3.3 and 7.1 times greater, respectively, compared to that by municipal governments.