Modelling, simulation and optimization of anaerobic acidogenic plug flow reactors

Abstract

Researches for renewable energy sources is increasing considerably nowadays, due to a possible shortage of fossil fuels in the future. In this sense, 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 converts it into biogas, hydrogen or methane. Hydrogen, compared to methane, has an even greater interest, since during its combustion process it produces only water as product. In these acidogenic bioreactors, microorganisms degrade different types of substrate and produce hydrogen and organic acids. However, as important as knowing the experimental process of this biogas production, it is also important to perform the mathematical modeling of the process for simulation in other scenarios and to scale up it. The most widely used model for modeling anaerobic 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 process, in which the final product is methane. However, modifications in its structure were made, thus this model was able to simulate the processing in batch acidogenic reactors. Therefore, further studies are required to use this model for simulations of bioreactors operated continuously and with piston flow. Consequently, there is much researches to be done in this area in the world and, mainly, in Brazil, where there is only one research group being nucleated at the University of São Paulo to work directly with modeling of anaerobic processes. Therefore, the objective of this work is to discretize the ADM1 and incorporate gas-liquid mass transfer equations for simulation of the AnTR (Anaerobic Tubular Reactor), AnSTBR (Anaerobic Structured Bed Reactor) and AnPBR (Anaerobic Packed Bed Reactor) reactors. (AU)