Conversão de energia elétrica por célula combustível microbiana (CCM) aplicada em reator anaeróbio-aeróbio tratando esgoto sanitário

Abstract

The scientific community has focused its efforts on search of sustainable solutions for the sócio-environmental problems caused by the generation of electric energy, from the burning of fossil fuels and their derivatives. The microbial fuel cell (MCC) is a promising technology to contribute to this energy issue, as it can convert chemical energy into electrical energy through the metabolism of microorganisms. And, from this concept, an anaerobic-aerobic reactor was built, containing an effective volume of 17,18 liters, with the insertion of 20 electrodes of graphite bars, in its interior, connected by means of a rigid copper cable to an external circuit. Thus, the present research aims to evaluate the conversion of electrical energy from the CCM applied to an anaerobic-aerobic reactor, treating sanitary sewage (synthetic). This study was divided into 4 operational stages: Stage l (20h TDH), Stage ll (12h TDH), Stage lll (10h TDH) and Stage lV (8h TDH), to investigate the best operational conditions to obtain the higher conversions into electrical energy. In Stage 1, the system presented a removal of 85% of COD, while Stage ll with a TDH of 12 hours, presented a removal of 89% of COD. Step III and IV obtained an efficiency of organic matter removal of 88% and 89%, respectively. The electrical voltages obtained by the system were higher in the second operational stage, if compared to the others, varying between 141 mV and 661 mV. The power density was also higher in the second stage, totaling 389,31 mW m-2 generated in the system. Changing the hydraulic detention time of the combined reactor significantly interfered with the conversion of electrical energy in the MCC, and the best performance in the generation of electricity by the system was recorded in the 12 hour TDH. Furthermore, the variation in the concentration of carbonaceous organic matter, in terms of COD, has also been shown to influence the process of conversion into electrical energy.