Enabling microbial electrolysis cell scale-up via electrochemistry-, hydrodynamic-, and microbial ecology-informed...

Area of Science:

• Electrochemical Engineering
• Environmental Biotechnology
• Microbial Ecology

Background:

• Microbial electrolysis cells (MECs) offer sustainable hydrogen production and wastewater treatment.
• Scaling up MECs has historically resulted in performance loss compared to lab-scale systems.
• The reasons for performance discrepancies during MEC scale-up remain poorly understood.

Purpose of the Study:

• To develop a framework for analyzing and optimizing MEC performance during scale-up.
• To quantify limitations and identify strategies for achieving equivalent performance at larger scales.
• To advance electrochemical biotechnology for practical wastewater treatment applications.

Main Methods:

• Developed a combined electrochemistry-, hydrodynamic-, and microbial ecology-informed framework.
• Applied the framework to scale up a zero-gap MEC from 9 cm² to 100 cm² electrode area.
• Utilized COMSOL simulations for flow dynamics and high-throughput sequencing for microbial analysis.

Main Results:

• Achieved similar maximum current densities (9 cm²: 25.1 ± 2.7 A/m²; 100 cm²: 21.7 ± 1.1 A/m²).
• Maintained equivalent hydrogen production rates (9 cm²: 67.7 ± 2.4 L/L-d; 100 cm²: 69.3 L/L-d).
• Minimized internal resistance increase and characterized microbial community differences across scales.

Conclusions:

• The developed framework effectively guides MEC scale-up by integrating key performance parameters.
• This approach facilitates achieving comparable performance in larger-scale MEC systems.
• Contributes to the practical deployment of energy-efficient electrochemical wastewater treatment.