Method to sustain culture activity, gas uptake and improve selectivity for ethanol production during syngas or producer gas fermentation in bioreactors

BACKGROUND

Global energy demand continues to rise while fossil fuel reserves decline, heightening the need for sustainable alternatives such as biofuels. Syngas- a mixture of carbon monoxide (CO), hydrogen (H₂), and carbon dioxide (CO₂)- can be biologically converted into valuable chemicals including alcohols through microbial fermentation. However, efficient and selective bioconversion is hindered by several challenges, notably the low solubility of CO and H₂ gases in the fermentation broth, which limits mass transfer and substrate availability for bacteria. Additionally, imbalances in gas supply can disrupt microbial metabolism, leading to reduced productivity and unwanted byproducts. Overcoming these mass transfer limitations and maintaining high microbial activity are essential for economically viable commercial alcohol production from syngas.

SUMMARY OF TECHNOLOGY

This technology introduces fine powdered activated carbon into a continuously stirred tank reactor (CSTR) during syngas fermentation to address the critical mass transfer bottleneck associated with sparingly soluble gases like CO and H₂. The activated carbon acts as a localized gas reservoir and facilitates electron transfer between microbial cells and substrates, enhancing microbial activity while mitigating toxic effects from gaseous intermediates. This results in significantly improved substrate uptake, shifts product selectivity towards high ethanol yields, and prolongs biocatalyst longevity. Experimental data demonstrates up to a 26-fold increase in ethanol concentration and extended microbial performance compared to traditional methods. Compatible with various syngas compositions and reactor types, this process also improves hydrogen utilization and optimizes mixing power input, thereby increasing energy efficiency, product yield, and overall operation cost-effectiveness making it a highly promising solution for sustainable biofuel production.

POTENTIAL AREAS OF APPLICATION

• Petrochemical Refinery Waste Streams; Processing CO, CO₂ & H₂
• Landfill Gas Conversion; Landfill Gas to Syngas
• Coal Gasification Plants; Enhance Gas-to-Liquid Mass Transfer
• Chemical Manufacturing Sector; Improved Ethanol Production
• Power Generation Industry; Improve Fuel Availability
• Oil & Gas Upstream Operations; Gas Byproduct Management & Reduced Environmental Impact

MAIN ADVANTAGES

• Increases Ethanol Yield & Selectivity
• Extended Fermentation Duration & Biocatalyst Activity; 470+ Hours
• Mitigation of CO Toxicity & Improved Microbial Health
• Applicability to Various Autotrophic Acetogenic Microbes

STAGE OF DEVELOPMENT

• Working Model