Passive Control of a Microbial Electrolysis Cell for the Production of Hydrogen From Agricultural Wastewater

This work presents a local Port-Hamiltonian-based control strategy for a microbial electrolysis cell aimed at regulating the substrate concentration through the dilution rate. The proposed approach combines an equilibrium-based formulation with a damping injection term inspired by the IDA-PBC methodology. A nonlinear model including substrate, anodophilic biomass, methanogenic biomass, oxidized mediator concentration, and current dynamics is considered. The controller performance is evaluated under changes in the operating point and variations in the inlet substrate concentration. The simulation results show accurate substrate regulation, bounded control effort, and a consistent internal response of the electrochemical and biological variables, supporting the usefulness of the proposed formulation as a control-oriented framework for microbial electrolysis cells.