Microbial Fuel Cell-driven caustic potash production from wastewater for carbon sequestration

Area of Science:

• Environmental Science
• Electrochemistry
• Biotechnology

Background:

• Microbial fuel cells (MFCs) offer a promising avenue for sustainable energy generation.
• Carbon dioxide (CO2) sequestration remains a critical challenge in mitigating climate change.
• Wastewater streams, particularly those rich in nutrients like urine, represent underutilized resources.

Purpose of the Study:

• To report the novel formation of caustic potash (KOH) on an MFC cathode.
• To demonstrate CO2 capture and conversion into potassium bicarbonate salt (kalicinite).
• To evaluate the potential for simultaneous electricity generation and CO2 sequestration using wastewater.

Main Methods:

• Utilizing potassium-rich wastewater as a microbial fuel source in an MFC anode.
• Analyzing the alkaline catholyte formed on the cathode surface (pH > 13).
• Mineralizing the captured CO2 into potassium bicarbonate salt (kalicinite).

Main Results:

• Caustic potash (KOH) was formed directly on the MFC cathode.
• The process generated electricity while simultaneously capturing CO2.
• The captured CO2 was successfully mineralized into potassium bicarbonate salt (kalicinite).
• The catholyte exhibited high alkalinity (pH > 13) and CO2 sorbent properties.

Conclusions:

• This MFC approach provides a cost-effective and environmentally friendly method for CO2 sequestration.
• The technology demonstrates potential for a carbon-negative economy.
• It offers a dual application for electricity production and nutrient recovery from wastewater for fertilizer use.