Solid-state ethanol fermentation by means of inert gas circulation

Area of Science:

• Biotechnology
• Biochemical Engineering
• Fermentation Technology

Background:

• Conventional fermentation methods for ethanol production face challenges with efficiency and waste management.
• Solid-state fermentation (SSF) offers potential advantages but requires optimization for industrial scalability.

Purpose of the Study:

• To develop and evaluate a new solid-state ethanol fermentation (SSEF) system for enhanced ethanol production from solid starchy materials.
• To optimize starch hydrolysis and ethanol production using specific microbial strains and fermentation conditions.

Main Methods:

• Utilized a packed-bed fermentor for solid-state ethanol fermentation.
• Employed Aspergillus saitoi cultivation and saccharifying enzyme enrichment for efficient starch hydrolysis.
• Implemented parallel fermentation with a respiration-deficient mutant of Saccharomyces cerevisiae.
• Integrated simultaneous ethanol stripping using inert gas circulation and condensation for recovery.

Main Results:

• Achieved an average ethanol concentration over 200 g/L in the condensate.
• Recovered over 90% of produced ethanol from the packed bed within 15-16 days.
• Attained a fermentation efficiency of approximately 80%, significantly higher than conventional SSF.
• Generated residue with reduced volume and higher solids content, suitable for fertilizer or feed conversion.

Conclusions:

• The developed SSEF system demonstrates high efficiency and ethanol recovery from starchy materials.
• This method presents a promising advancement over traditional fermentation techniques, with benefits in waste reduction and byproduct utilization.