Energy and Economic Evaluation of the Production of Biogas from Anaerobic and Aerobic Sludge in Brazil

摘要

This study conducted energy and economic analysis for biogas production from an Upflow Anaerobic Sludge Blanket (UASB) and activated sludge from the Copasa and Fania® Wastewater Treatment Plants (WWTP), both of which are located in the city of Itajuba, Minas Gerais, Brazil. The methodology adopted for the research study included Physicochemical laboratory analyses of sludge samples. Furthermore, an experimental prototype of a sludge anaerobic digester (AD) that measured the characteristics of biogas and methane discharge was constructed and monitored. Lastly, economic viability analysis for using biogas energy was studied. The results show that the substrate, following processing using an AD, had reductions in all of the physiochemical parameters evaluated. Furthermore, CH_4 yield in relation to volatile solids (VS) was 0.0046 Nm~3CH_4/kgSV (4.6 Nm~3CH_4/tSV), 32.89% VS for UASB sludge, 0.0019 Nm~3CH_4/kgSV (1.9 Nm~3CH_4/tSV), and 50.45% VS for activated sludge. UASB sludge samples had the best results, which were 1014.46 kWh/year of electrical energy generated at the Copasa WWTP. Economic feasibility analysis considered a project lifespan of 15 years for continuous power generation. The results showed a NPV of negative USD$-226,255.28, a LCOE of 1.40 USD/kWh, and an unfeasible Internal Rate of Return (IRR).