Membrane-less cloth cathode assembly (CCA) for scalable microbial fuel cells

Area of Science:

• Energy conversion and storage
• Environmental biotechnology
• Materials science

Background:

• Scaling up microbial fuel cell (MFC) technology faces challenges with cost-effective, high-power cathode development.
• Current cathode architectures are often expensive and complex, hindering widespread MFC adoption.
• Non-precious metal catalysts and conductive materials are sought for sustainable MFC designs.

Purpose of the Study:

• To develop a simple, low-cost, and scalable method for creating electrically conductive and catalytically active cathode architectures for MFCs.
• To evaluate the performance of novel cloth cathode assemblies (CCAs) in terms of power generation and wastewater treatment.
• To compare the efficiency and cost-effectiveness of CCAs against existing MFC cathode technologies.

Main Methods:

• A one-step method was employed to convert non-conductive canvas cloth into a conductive CCA by coating it with conductive paint (nickel-based or graphite-based) and manganese dioxide (MnO(2)) catalyst.
• Tubular air-chamber MFCs were constructed using the developed Ni-CCA and graphite-CCA.
• Performance was assessed by measuring power density, chemical oxygen demand (COD) removal, and coulombic efficiency in fed-batch mode using brewery wastewater.

Main Results:

• The Ni-CCA equipped MFC achieved a maximum power density of 86.03 mW m⁻² (projected cathode area) and 9.87 W m⁻³ (reactor liquid volume).
• The Ni-CCA exhibited significantly lower volume resistivity (1.35 x 10⁻² Ω cm) compared to graphite-CCA (225 x 10⁻² Ω cm), correlating with higher power output.
• MFCs with Ni-CCA and graphite-CCA demonstrated high COD removal (approx. 95%) and coulombic efficiencies of 30.2% and 19.5%, respectively, within 13-18 days.

Conclusions:

• The developed cloth cathode assembly (CCA) offers a mechanically durable, economical, and scalable solution for MFC technology.
• The Ni-CCA demonstrated superior performance in power generation and wastewater treatment compared to graphite-CCA, attributed to its lower electrical resistance.
• This cost-effective cathode design, utilizing non-precious metal catalysts, represents a significant advancement for practical MFC applications.