High-Solids Ethanol Fermentation via Dual Pretreatment
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Solution Overview
Problem
Ethanol yield decreases and by-product inhibition occurs during ethanol fermentation with high solid concentrations due to poor heat and mass transfer, enzyme binding with lignin, and low water concentrations.
Innovation Solution
A method of ethanol fermentation with cellulose at high-solids loading involves pretreating lignocellulose with NaOH and AlCl3-enhanced ethanol solutions, followed by simultaneous saccharification and fermentation with cellulase and yeast activation solution, and batch supplementation of dry cellulose to maintain optimal water content and enzyme accessibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high solid concentration is used in ethanol fermentation, then equipment utilization rate increases and production cost decreases, but ethanol yield decreases due to poor heat and mass transfer
Solution Approach 1:
The patent applies preliminary action by conducting pretreatment of lignocellulose before fermentation to improve enzyme accessibility. The pretreatment process modifies the substrate structure in advance to prevent enzyme binding with lignin during fermentation, thereby maintaining high ethanol yield even at high solid concentrations (30-50%).
Solution Approach 2:
The patent changes physical and chemical parameters of the substrate through pretreatment methods. By adjusting parameters such as temperature, pressure, and chemical composition during pretreatment, the substrate structure is optimized to improve heat and mass transfer while maintaining high solid concentration, thus resolving the contradiction between productivity and ethanol yield.
2Productivity
If high solid concentration is used in ethanol fermentation, then production cost decreases, but by-product concentration increases causing inhibitory effect on microorganisms
Solution Approach 1:
The patent applies the taking out principle by selectively removing or reducing harmful by-products through optimized fermentation conditions and pretreatment. This extraction of harmful factors reduces their inhibitory effect on microorganisms while maintaining high solid concentration, thereby keeping production cost low without sacrificing microbial activity.
Solution Approach 2:
The patent uses intermediaries such as optimized buffer systems and pH control agents to mitigate the harmful effects of by-products. These intermediaries help maintain optimal fermentation conditions even when by-product concentrations are high, reducing their inhibitory impact while allowing high solid concentration fermentation to proceed cost-effectively.
3Productivity
If high substrate loading is used, then ethanol production efficiency increases, but water concentration decreases leading to poor mass transfer
Solution Approach 1:
The patent applies local quality by creating localized water-rich environments around the substrate particles through controlled addition of water or aqueous solutions during fermentation. This ensures sufficient water concentration for mass transfer in specific local regions while maintaining overall high substrate loading, thereby preserving both ethanol production efficiency and mass transfer capability.
Solution Approach 2:
The patent addresses the water concentration issue by transitioning from a homogeneous liquid phase to a structured system with multiple phases or dimensions. By using solid-supported substrates or structured reactors, the system creates distinct zones where water can be effectively utilized for mass transfer even at high overall substrate concentrations, thus maintaining ethanol production efficiency.
4Productivity
If high solid concentration is used, then substrate transport efficiency decreases due to water binding to biomass, but ethanol yield needs to be maintained
Solution Approach 1:
The patent applies preliminary action by pre-modifying the substrate structure through pretreatment to reduce water binding capacity before fermentation. This preliminary modification prevents excessive water binding during high solid concentration fermentation, maintaining substrate transport efficiency and ensuring high ethanol yield is achieved.
Solution Approach 2:
The patent changes the physical and chemical parameters of the substrate through pretreatment to alter water binding characteristics. By adjusting parameters such as moisture content, surface area, and chemical composition, the substrate is optimized to maintain adequate water availability for transport and reaction even at high solid concentrations, thereby maintaining both substrate transport efficiency and ethanol yield.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method significantly increases ethanol yield and reduces fermentation time by optimizing water content and enzyme accessibility, while minimizing by-product inhibition.
Implementation Method 1
adding cellulase and a yeast activation solution to the sterilized solution, and then performing simultaneous saccharification and fermentation
Implementation Method 2
simultaneous saccharification and fermentation
Implementation Method 3
adding cellulase and a yeast activation solution to the sterilized solution, and then performing simultaneous saccharification and fermentation
Data Source
AI summary
The present invention provides an ethanol fermentation method with cellulose at high-solids loading. The method includes: mixing lignocellulose A treated with NaOH-enhanced ethanol solution and lignocellulose B treated with AlCl3-enhanced ethanol solution, adding water, and mixing to obtain a mixed cellulose solution; then adding a nutrient salt, sterilizing, saccharifying and fermenting, and supplementing mixed cellulose in the fermentation process; and after the completion of material supplementation, mixing the mixed cellulose and water according to a mass ratio of (30-45):100.