Modular multi-cathode microbial electrosynthesis enabling predictable scale-out conversion of CO₂ to acetate

Area of Science:

• Bioelectrochemical engineering
• Sustainable chemistry
• Carbon capture and utilization

Background:

• Microbial electrosynthesis (MES) offers a sustainable route for converting CO2 into valuable chemicals.
• Scaling up conventional MES reactors is hindered by issues with electrochemical and biological uniformity, leading to performance degradation.

Purpose of the Study:

• To propose and evaluate a modular multi-cathode chamber MES configuration for reliable and scalable CO2-to-acetate electrosynthesis.
• To demonstrate that this design overcomes uniformity challenges during scale-out.

Main Methods:

• A modular multi-cathode MES reactor was developed, sharing a single anode across multiple isolated cathode chambers.
• The system was scaled from 0.25 L to 2 L by increasing the number of cathode chambers.
• Acetate production, biofilm density, faradaic efficiency, and carbon recovery were analyzed at different scales.

Main Results:

• Acetate production demonstrated a linear correlation with reactor volume and cathode area (R² = 0.99) over an eightfold scale increase.
• Key performance metrics, including surface-normalized biofilm density and faradaic efficiency, remained consistent across scales.
• Bioelectrochemical performance was maintained without compromise during the scale-out process.

Conclusions:

• The modular multi-cathode configuration enables linear and predictable scaling of MES.
• This approach maintains bioelectrochemical uniformity, paving the way for practical, large-scale CO2-to-acetate production.