Microbial electrolysis desalination and chemical-production cell for CO2 sequestration

Area of Science:

• Environmental Science
• Geochemistry
• Biotechnology

Background:

• Mineral carbonation is a slow process for CO2 sequestration.
• Accelerating mineral dissolution and carbonate precipitation is key to efficient carbon capture.

Purpose of the Study:

• To investigate the use of acid and alkali generated from a microbial electrolysis desalination and chemical-production cell (MEDCC) to enhance mineral carbonation for CO2 sequestration.
• To assess the efficiency of CO2 absorption and precipitation as carbonates using natural serpentine minerals.

Main Methods:

• Utilized acid generated in a MEDCC to dissolve magnesium/calcium silicates (serpentine).
• Employed alkali from the same MEDCC process to absorb CO2 and precipitate magnesium/calcium carbonates.
• Monitored dissolved ion concentrations, CO2 absorption, carbonate precipitation, chemical oxygen demand (COD) removal, and desalination.

Main Results:

• Dissolved Mg(2+) and Ca(2+) concentrations from serpentine increased 20 and 145 times, respectively, using the acid solution.
• Under optimal conditions, 24 mg of CO2 was absorbed and 13 mg precipitated as carbonates per fed-batch cycle (24h).
• The MEDCC achieved 94% COD removal and 22% desalination.

Conclusions:

• The MEDCC process significantly accelerates mineral carbonation for CO2 sequestration.
• This integrated approach offers a viable method for carbon capture using renewable organic matter and natural minerals.
• The process simultaneously addresses wastewater treatment (COD removal) and desalination.