Enhancing methane oxidation in a bioelectrochemical membrane reactor using a soluble electron mediator

Area of Science:

• Environmental Science
• Electrochemistry
• Microbiology

Background:

• Bioelectrochemical methane oxidation by anaerobic methanotrophic archaea (ANME) is limited by methane bioavailability and slow extracellular electron transfer (EET).
• Optimizing methane delivery and electron transfer kinetics are crucial for enhancing system performance.

Purpose of the Study:

• To improve the performance of methane-driven bioelectrochemical systems.
• To investigate the combined effect of hollow fibre membranes (HFMs) and a soluble redox mediator (ferricyanide) on methane oxidation.

Main Methods:

• Utilized hollow fibre membranes (HFMs) for efficient methane delivery to ANME.
• Amended the system with ferricyanide to act as a soluble redox mediator, facilitating electron transfer between ANME and the anode.
• Assessed performance by measuring current density (mA m⁻²).

Main Results:

• The combined use of HFMs and ferricyanide significantly increased the performance of ANME-based bioelectrochemical methane oxidation.
• Achieved a current density of up to 196 mA m⁻², which is 244 times higher than the control system.
• Demonstrated enhanced performance when HFMs were pressurized at 1.6 bar.

Conclusions:

• Improving methane delivery and extracellular electron transfer (EET) are critical for enhancing bioelectrochemical methane oxidation.
• Process engineering, including optimized methane delivery and mediator use, enables efficient energy recovery from direct methane oxidation.