Avaliação do potencial de aproveitamento energético do biogás para secagem de lodo em 6 estações de tratamento de esgoto do estado de Sergipe que possuem reatores anaeróbios

Abstract

The management of organic solid waste produced in sanitary sewage processes and the collection of solid urban waste are relatively recent activities in the world, resulting from pressure from environmental agencies in recent decades. As a way of maximizing energy management from sewage treatment plants (STP), some sanitation companies in the world aim to take advantage of renewable sources, as is the case with biogas. The burning or release of this gas into the atmosphere characterizes financial waste and environmental damage. The use of biogas energy can offer important environmental, economic, energy and social benefits, representing an alternative and renewable source of energy increasingly used worldwide. The treatment of effluents through anaerobic digestion is shown to be advantageous when compared to aerobic digestion, occupies smaller areas, has low energy consumption and solid production, and is favored by climatic conditions in Brazil. UASB reactors (Upflow Anaerobic Sludge Blanket) represent the most effective method among anaerobic digestion methods, as they generate by-products with high energy potential. Therefore, this undergraduate thesis aims to evaluate the efficiency of the biogas generated in 6 UASB reactors in the state of Sergipe, as an energy source for thermal cleaning of the sludge produced in each STP. Based on data provided by the Companhia de Saneamento de Sergipe-DESO, it was estimated the generation of biogas with the help of the Probio software, for each STP under study. As well as, a methodology proposed in the specialized literature was used, which considers the conversion routes of COD (Chemical Oxygen Demand) and methane losses inside the reactor not considered in the most traditional methodologies. The results found confirm that the concentration of methane in the biogas produced in UASB reactors treating domestic sewage is suitable for use in energy cogeneration, burning, drying and sludge hygienic units. Among the 6 STP's studied in this work, all have values below 8 kWh / Nm³biogas, making available chemical energies (kWh / day) of little advantage for recovery, however, efficient for cleaning the sludge generated in the UASB reactors.