Modelling, simulation and optimization of a plug-flow acidogenic reactor

Abstract

Researches for renewable energy sources are increasing nowadays, due to a possible scarcity of fossil fuels in the future. In this context, a promising alternative for clean energy is the treatment of domestic or industrial effluents using the anaerobic digestion process in bioreactors, in which microorganisms degrade complex organic matter and convert it into biogas, hydrogen or methane. Hydrogen, compared to methane, is even more interesting, because during its combustion process it produces only water (2H2+O2 ’2H2O). In these acidogenic bioreactors, microorganisms degrade different types of substrates and produce hydrogen and organic acids. However, as important as knowing the experimental process to produce biogas, itis also important to perform a mathematical modeling to simulate the process in other scenarios and for scale-up. The most widely used model for modeling of anaerobic digestion processes is the Anaerobic Digestion Model Number 1 (ADM1), proposed in 2002 by the Task Group of the International Water Association. This model was formulated for a complete anaerobic digestion, in which the end product is methane. However, modifications were made in its structure to the model be able to simulate the processing of acidogenic batch reactors. Therefore, further studies are required for this model be used in simulation of bioreactors operated continuously and with a plug-flow regime. Therefore, the objective of this work is to discretize the ADM1 and incorporate gas-liquid mass transfer equations for simulation of a continuous plug-flow reactor called Anaerobic Structured Bed Reactor (AnSTBR), which was used previously in lab-scale experiments for the production of biohydrogen. (AU)