Hydrogen Production in Microbial Electrolysis Cells Using an Alginate Hydrogel Bioanode Encapsulated with a Filter...

Area of Science:

• Bioelectrochemical systems
• Microbial electrolysis cells (MECs)
• Renewable energy
• Wastewater treatment

Background:

• The bacterial anode limits hydrogen evolution reaction (HER) efficiency in microbial electrolysis cells (MECs).
• Improving biofilm attachment and stability on the anode is crucial for enhanced performance.
• Existing bioanodes often suffer from low mechanical strength and susceptibility to degradation in wastewater.

Purpose of the Study:

• To enhance biofilm attachment and stability on the carbon-cloth anode of MECs.
• To improve the overall bio-electrochemical activity and hydrogen production efficiency.
• To develop a robust bioanode system suitable for operation with real wastewater.

Main Methods:

• Developed an alginate hydrogel to improve biofilm attachment to the carbon-cloth anode.
• Encapsulated the alginate-modified bioanode within a filter bag to enhance mechanical strength and prevent degradation.
• Compared the performance of the encapsulated alginate bioanode against bare, alginate-only, and encapsulated-only bioanodes in MECs, using both synthetic medium and real wastewater.

Main Results:

• The encapsulated alginate bioanode demonstrated a significant decrease in charge transfer resistance (Rct) from 240.2 Ω to 9.8 Ω over three weeks.
• MECs with the encapsulated alginate bioanode achieved the highest current density (9.21 ± 0.16 A·m⁻²) with wastewater, outperforming controls by 20% to 180%.
• This configuration also yielded the highest reduction currents (4.14 A·m⁻²) and hydrogen production rate (0.39 m³·m⁻³·d⁻¹), with Geobacter dominating the microbial community (79%).

Conclusions:

• Encapsulating an alginate hydrogel-modified bioanode in a filter bag significantly enhances bio-electrochemical activity and stability in MECs.
• This approach effectively preserves biofilm integrity, leading to superior electron transfer rates and improved hydrogen production.
• The developed system shows great promise for efficient wastewater treatment and sustainable hydrogen generation.