Análise dos custos operacionais de uma estação de tratamento de esgoto de instituição federal de ensino superior

Abstract

The performance indicators serves as a supporting resource for monitoring the effectiveness and efficiency of management and practice in sanitation services. Thus, it must include, in addition to social and environmental indicators, economic indicators linked to operating and maintenance (O&M) expense. This work presents the O&M costs of a sewage treatment plant (ETE) of a federal institution of higher education (IFES) by activated sludge with prolonged aeration, located in the city of Natal/RN, with the main objective of determining the O&M expense per m³ of treated sewage, as well as categorizing them into six different categories, according to the methodology proposed by Souza (2019). To this end, the constituents of the ETE’s O&M expense for the year 2019 were surveyed, since on March 18, 2020 the Federal University of Rio Grande do Norte (UFRN) suspended face-to-face activities due to the Covid-19 pandemic, which greatly reduced the flow of sewage affluent referred to ETE. The average cost of O&M per cubic meter found was R$ 5.24, corresponding to a higher value than that found in the literature due to the size of this ETE. The categories with the most representative expenses were related to administrative and electricity, corresponding to 70.27% and 19.34%, respectively. For energy expense, there was greater expense in the aeration step in the oxidation value, representing more than 50% of the cost of this category, similar to ETE Barueri, which has the same type of treatment. The feasibility of reusing treated sewage for irrigation was also verified, showing savings of more than 1 million reais for UFRN compared to the use of potable water.