VIABILIDADE DE COGERACAO DE ENERGIA ELÉTRICA COM O BIOGAS PROVENIENTE DO TRATAMENTO DE ESGOTOS DOMESTICOS.

Abstract

This work goals to study the technical and economic aspects of the feasibility of energy cogeneration ­ electrical and thermal ­ using the biogas spawn from digesters from sewage anaerobes treatment plants (UASB) limited to three of these UASB's plants owned by the COMPANHIA DE SANEAMENTO BASICO DO MARANHAO ­ CAEMA with anaerobic reactors of the UASB type available and in operation. It also aims to demonstrate the possibility of recovering biogas produced by the treatment of domestic sewage by anaerobic process of digestion and subsequent purification even to meet the technical specifications of its use, as a fuel for power generation. In witch It concerns to economic and financial aspects It also aims to analyze and verify the economic feasibility at a conception study standard of the energy cogeneration asset investments in sewage plants of various sludge treatment and generation capacity sizes having as premises the electricity consumption reduction which represents a relevant weighting in the expenses of the sanitation sector total expenses energy charged by supplier companies and the dried sludge transport costs reduction from the ETEs with the reduction of its volume with the use of heat energy from the cogeneration to Its thermal drying. Finally as an environmental completing aspect It analyses the energy cogeneration with methane fuel use as an alternative burning to the methane produced by the sewage plants as established in the ABNT standard thus contributing to the greenhouse gas emissions reduction goals of a current relevance GHG and to take advantage of the clean thermal energy by using the exhausting heat gases from the generators besides the thermal drying of the sewage sludge with Its hygiene and pathogenic microorganisms removal that presents an environmental and public health policies possibility for the Basic Sanitation sector. Using the methodology for the decay of chemical oxygen demand (COD) from the literature, the volume of biogas produced was estimated and the investment and operating costs were valued and the Economic Engineering investment analysis techniques were applied, also, as with the risk analysis of investments, results were obtained that prove the financial and economic viability of investments in energy cogeneration, which is the object of this study.