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The Production of Sewage Biogas and its Use for Energy Generation
Prof. Dra. Suani Teixeira Coelho1
[email protected]
M. Sc. Sílvia Stortini González Velázquez1
[email protected]
M.Sc. Silva, Orlando Cristiano1
[email protected]
M. Sc. Varkulya, Américo Jr. 1
[email protected]
Pecora, Vanessa1
[email protected]
Abreu, Fernando Castro1
[email protected]
1
IEE / CENBIO – Institute of Electrotechnics and Energy / Brazilian Reference Center on Biomass, USP University of São Paulo, São Paulo, Brazil.
ABSTRACT
Purpose: The project proposal of sewage use to produce biogas and this last one as fuel to electric energy
generation. Its development is a commitment of CENBIO (Brazilian National Biomass Reference Center),
and it is, in fact, one between others projects developed by a Sao Paulo University Program named
PUREFA (Program of Rational Energy Use and Alternative Sources), which aims to increase the renewable
energy participation in the University’s energetic matrix, as well as it allows new perspectives for
renewable energy employment in Brazil. In this context, this abstract presents a pilot project for biogas
conversion in Brazil. The project aims to increase the biogas conversion efficiency, by using it as fuel to
produce electricity.
The biogas is generated at Sao Paulo University campus, in a UASB (Up-flow Anaerobic Sludge Blanket)
biodigestor, feed in this project, with liquid effluents provided by residential buildings, located in the
University, presenting a mass flow rate equivalent to 3 m3 per hour.
Results: The biogas results from organic material anaerobic fermentation and its chemical composition
depends on several parameters. The biodigestor employed and the kinds of organic material are two of
them. Anyway, the most important biogas components are methane (CH4), carbon dioxide (CO2) and
sulfuric components (H2S). The biogas composition is an essential parameter to energy generation, because
it allows identifying the appropriate purification system, which aims to remove sulfuric gases and
decreasing the water volume, contributing to improve the combustion fuel conditions. So, two analysis of
the biogas composition were made, one before the pre installation of the purification system and another
after it. Another data obtained from biogas analysis refers to the low heat value, that combined to the
efficiency and biogas consumption is important to estimate the electric generation potential. The low heat
value depends on the residence time of the sewer in the biodigestor, about eight hours, and the
characteristics of the effluent sewer, so two analysis of the sewer effluent were made, one before and the
another after the biodigestor.
Conclusion: This project is currently under development and the results obtained will provide information
about the biodigestor´s operational conditions, defining appropriate areas where this project could be
applicable to generate decentralized energy. The most important environmental contribution associated to
this project is the mitigation of greenhouse gases (GHG) emissions, especially verified trough methane
conversion in carbon dioxide, which presents a dangerous level around twenty five times lower than
methane.