Microbial Electrolysis Cells Based on a Bacterial Anode Encapsulated with a Dialysis Bag Including Graphite Particles

Area of Science:

• Microbial Electrochemistry
• Bioelectrochemical Systems
• Wastewater Treatment

Background:

• Bacterial anodes in microbial electrolysis cells (MECs) are often hindered by non-exoelectrogenic bacteria, which impede current transfer and reduce hydrogen production.
• These non-exoelectrogens form physical barriers and compete for nutrients, negatively impacting MEC efficiency.

Purpose of the Study:

• To improve the performance of MECs by enhancing current transfer from the bacterial anode.
• To investigate the effect of encapsulating the bacterial anode with suspended graphite particles within a dialysis bag.

Main Methods:

• A novel anode design involving encapsulation within a dialysis bag containing suspended graphite particles was developed.
• Control groups included an anode encapsulated in a dialysis bag without graphite and a bare anode.
• Performance was evaluated using artificial wastewater and Geobacter medium, measuring current density, hydrogen production rate, areal capacitance, and COD removal.

Main Results:

• The MEC with the graphite-dialysis-bag anode achieved significantly higher current density (2.73 A·m⁻²), hydrogen production rate (7.6 × 10⁻² m³·m⁻³·d⁻¹), and areal capacitance (134.13 F·m⁻²) compared to controls.
• Electrochemical impedance spectroscopy revealed the lowest charge transfer resistance (35 Ω) for the modified anode.
• Higher Chemical Oxygen Demand (COD) removal (53%) was observed with Geobacter medium compared to artificial wastewater (40%).

Conclusions:

• Encapsulating bacterial anodes with graphite particles effectively overcomes limitations posed by non-exoelectrogenic bacteria.
• This modification substantially enhances MEC performance, including current generation and hydrogen production.
• The graphite-dialysis-bag anode shows promise for efficient wastewater treatment and bioenergy production in MECs.