Análise do aproveitamento energético do biogás no process de tratamento de esgoto sanitário: estudo de caso em uma Estação de Tratamento de Esgoto em Minas Gerais

Abstract

The energy recovery of biogas in sanitary sewage treatment plants represents a sustainable alternative for the sanitation sector, contributing to the energy transition and the reduction of environmental impacts. This study aimed to evaluate the potential for biogas production at a Sewage Treatment Plant located in the state of Minas Gerais, Brazil, through the analysis of operational performance, the gas mass balance, and the removal efficiencies of the treatment units. This is a case study developed from a technical visit, consultation of historical monitoring data, which are public and accessible on the operator's official channels, and computational processing using spreadsheets elaborated in Microsoft Excel software, based on established methods for estimating methane production described by Chernicharo (2007) and Ramos (2008). The results demonstrated high efficiency in the removal of DQO, DBO, total suspended solids, and nitrogen compounds, indicating adequate performance of the biological units. However, the organic underload resulting from the excessive dilution of the influent during rainy periods compromised the stability of the reactors and significantly reduced the biogas generation potential. The comparative analysis between design values, operational data, and statistics revealed significant discrepancies in influent loads, reflecting structural limitations of the drainage basin and hydraulic interferences resulting from illegal stormwater inflows. It is concluded that, although the installed technology has the capacity for significant biogas production, energy recovery only becomes viable when the system operates with loads compatible with its design, reinforcing the need for control actions in the collection network.