Pseudo bond graph modeling of wastewater treatment bioprocesses

The modeling of biotechnological processes is a complex task, because of the high interaction degree of the phenomena, non-linearities, and uncertainties of reaction kinetics. A novel approach for bioprocess modeling, based on pseudo bond graphs, is proposed in this paper. Bond graph method is an appropriate tool for modeling non-linear processes, eventually along with their control systems. Firstly, the pseudo bond graph method is applied in order to model some prototype bioprocesses starting from the reactions schemes and taking into account the biochemical phenomena. Then the rules used for the design of these models are applied on two widespread wastewater treatment processes. The first is an activated sludge bioprocess taking place in a sequential batch reactor, and the second is a wastewater biodegradation with the production of methane gas, which is carried out inside a continuous stirred tank bioreactor. The obtained bond graph models and several simulations are conducted using the 20sim modeling and simulation environment. This modeling procedure represents a valuable illustration of the power of the bond graph technique, and can be used as a base for the development of models of bioprocesses with a high level of complexity.