Utilização de cogeração de energia elétrica e térmica para melhorar a etapa de secagem do lodo de excesso de reator UASB
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Data
2025-03-14
Autores
Zardo Junior, Orlando
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Universidade Federal do Espírito Santo
Resumo
The interdependence between water, energy, and food is central to sustainable development, especially in the face of challenges such as climate change and urbanization. This study assesses the cogeneration of electrical and thermal energy in a solar drying system for sludge from a UASB (Upflow Anaerobic Sludge Blanket) anaerobic reactor, aiming for energy efficiency and economic feasibility. The research integrates an off-grid photovoltaic (PV) system with a solar greenhouse, analyzing the influence of temperature on heat and mass transfer during drying, in addition to economic indicators such as payback, IRR, and EROI. The methodology applied includes: 1) Solar drying – use of a chapel-type greenhouse, with resistive loads inside, coupled to a solar collector with a blower; 2) Economic indicators – calculation of payback, internal rate of return (IRR), and energy return on investment (EROI) to assess the profitability of the photovoltaic system; 3) Environmental analysis: quantification of the carbon emissions avoided by replacing fossil fuel sources with solar energy. The main results were: 1) Solar drying efficiency – average temperatures from 35°C to 67°C inside the greenhouse, with an 85% reduction in sludge volume; 2) Specific energy consumption of 1.55 kWh/kg of evaporated water, lower than thermal methods (between 1.77 and 2.86 kWh/kg); 3) Economic feasibility – payback of 6.15 years for the photovoltaic system, with an IRR of 12% per year and an EROI of 8.3, higher than the global average (between 6 and 8); 4) Avoided carbon: 5.36 tons of CO2 over 25 years; 5) Biosolid as a resource: total solids content >70%, suitable for agricultural use (CONAMA Class B); 6) 99.9% reduction in Escherichia coli load, ensuring sanitary safety. Conclusions: The integration of photovoltaic systems with solar drying proved to be technically and economically feasible, aligning with the principles of Sustainable Development Goals (SDG) 6 and the Brazilian National Solid Waste Policy (Law No. 12,305/2010).
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Palavras-chave
Secagem solar , Cogeração , Fotovoltaico , Viabilidade econômica , Solar drying , Cogeneration , Photovoltaic , Economic feasibility