Economic growth of Brazil is largely supported by bioethanol production, which is a biofuel obtained from a renewable material, and its combustion is less aggressive to the environment, as compared to fossil fuels. Nevertheless, each liter of bioethanol generates approximately between 10 and 15 L of vinasse, which contains high amount of organic matter, as well as antibacterial and recalcitrant compounds. Currently, vinasse is used as a fertilizer in sugarcane cultivation, causing negative impacts on microorganisms, plants and groundwater. Thus, facing to the need of improving the sustainability of the biorefinery, research about the treatment of its wastes has been increased. Anaerobic digestion has been considered as an attractive method to stabilize the organic matter from vinasse, since it recovers sustainable energy, such as H2 and other products of chemical interest. Notwithstanding, the energy recovery is low and the yield is thermodynamically limited to 4 mol H2 per mol of glucose, although the theoretical stoichiometric potential is 12 mol H2 mol-1. In this sense, a microbial electrolysis cell (MEC), an emerging type of bioelectrochemical system (BES), in where the redox metabolism is driven by a small input energy, has been used to overcome such that thermodynamic limit. Therefore, this postdoc research project proposes the application of a hybrid fermentative/MEC system. In a first step, in an acidogenic anaerobic reactor the carbohydrates will be consumed, which leads the formation of organic acids. As a second step, the effluent rich in organic acids will be used as substrate in a MEC. Thus, such sequential system allows improving the energy recovery, in the form of H2 and/or other valuable products, compared with a classical fermentative process.
News published in Agência FAPESP Newsletter about the scholarship: