Modeling of a Microbial Fuel Cell fed with a substrate of slow biodegradability

Microbial fuel cells (MFCs) degrade organic matter through the activity of electroactive microorganisms. The significance lies in utilizing organic waste, particularly digestate waste, due to its complex organic substrate of slow biodegradability. Given the considerable interest in this process, a model that represents the dynamics of these substrates and their correlation with the current production, is presented. The model encompasses the hydrolysis and diffusion stages in the biofilm of a slowly biodegradable organic matter component. The electroactive bacteria's activity induces hydrolysis, transforming it into rapidly biodegradable organic matter and subsequently into a flow of electrons delivered to the anode. The model comprises ten differential equations describing the behavior of the slowly biodegradable organic matter component and the rapidly biodegradable matter in the biofilm layers, a differential equation representing the charge accumulation in the biofilm, and the non-linear Buttler-Volmer equation. An identification procedure was undertaken to determine the values of the nine parameters utilized in the model. Subsequently, an experimental validation of the model was conducted, demonstrating its successful representation of the behavior of the MFC when fed with the digestate.