Energy use evaluation of biogas from UASB reactors in great Goiania sewage treatment plants

This work addresses some measures for the use of biogas from UASB Reactors in compact sewage treatment plants. The study was conducted in real units located in the great Goiânia, capital of the state of Goias - Brazil. The research covered qualitative and quantitative aspects and was based on data collection in the field, on the follow up of laboratory tests and on the volume and quality of the gas produced. After the theoretical definition of the methane volume, the on-site quantification phase was performed. In order to do so, it was necessary to install a filter and a flowmeter at STP Campos Dourados, belonging to Saneago Company. A percentage of 71.08% of the calculated theoretical value was reached for the initial measurements. The justification for the result was determined by the occurrence of some leaks in the three-phase separator of the reactor. Some interventions of the maintenance team were proposed, aiming the correction of the leaks, in order to allow a real comparison between the measured values and the calculated. At the end, was estimated the power for the installation of an electric power generator for the STPs under study, considering the continuous operation or only at peak hours. The generated energy was also evaluated and, consequently, the value saved with the energy concessionaire.