Automated real-time feeding control for microbial electrolysis cell-anaerobic digestion systems using finite state machine

Abstract

Abstract This study investigates the use of biosensor-led control in Microbial Electrolysis Cell-Anaerobic Digestion (MEC-AD) systems to enhance operational stability. Traditional methods depend on human operators to interpret data and adjust processes, whereas this research employed a current threshold-based Finite State Machine (FSM) for automated control in lab-scale, single-chamber MEC-AD reactors operated continuously for four months. By monitoring current draw as an indirect electrochemical proxy for microbial substrate-utilisation activity, the study facilitated real-time control of feeding events based on current responses to organic loading. Results show that, under the tested lab-scale conditions, this method enabled adjustment of feed volume and timing in response to changes in system conditions and microbial activity. Using an FSM provided a structured framework that links current responses to feeding events and defined system states, enabling predictable management of the MEC-AD process. Using molasses as feedstock, the research demonstrates effectiveness across reactors with varied hydraulic retention times at lab scale, indicating potential for further investigation into scalability and automation. This approach offers a promising alternative for optimising the performance of continuous operation AD systems, ensuring better control and lower risk of overload failures.