Sequential Two-Stage Ethanol Fermentation Process
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Solution Overview
Problem
Current ethanol production methods from lignocellulosic biomass face challenges such as high risk of contamination and longer hydrolysis times due to high sugar concentrations and enzyme inhibition, which limit ethanol yield and productivity.
Innovation Solution
A process involving sequential saccharification and co-fermentation using cellulase enzymes from two different sources, where the first enzyme is added during initial fermentation at 30-37°C, followed by a second enzyme at elevated temperature for hydrolysis, and then cooling for secondary fermentation, optimizing conditions for C5 and C6 sugar conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If simultaneous saccharification and fermentation (SSF) is used, then reaction time is reduced and contamination risk is minimized, but ethanol inhibits enzymatic hydrolysis and optimal conditions for both processes cannot be achieved
Solution Approach 1:
The patent divides the simultaneous saccharification and fermentation process into two sequential stages: first stage performs saccharification at 50°C to convert cellulose to sugars, then second stage performs fermentation at 30°C to convert sugars to ethanol. This segmentation allows each process to occur under its optimal conditions without mutual interference, resolving the contradiction between reaction time reduction and ethanol inhibition.
Solution Approach 2:
The patent performs saccharification as a preliminary action before fermentation. By first converting cellulose to fermentable sugars at 50°C, then subsequently performing fermentation at 30°C, the process ensures that enzymatic hydrolysis occurs without ethanol inhibition, while still achieving high productivity through the sequential optimization of both stages.
2Object-affected harmful factors
If separate hydrolysis and fermentation (SHF) is used, then optimal conditions for enzymatic hydrolysis and fermentation can be achieved, but hydrolysis time increases and contamination risk increases due to long reaction time and high sugar concentration
Solution Approach 1:
The patent merges the advantages of both SSF and SHF by implementing a sequential two-stage process that combines the optimal condition separation of SHF with the time efficiency of SSF. The process achieves optimal temperatures for each stage while maintaining a compact overall timeline through continuous operation without extended idle periods between stages.
Solution Approach 2:
The patent changes temperature parameters between stages: maintaining 50°C during saccharification for optimal enzymatic activity, then reducing to 30°C for fermentation. This parameter change allows each process to proceed under its optimal conditions while the sequential design prevents the contamination risks associated with prolonged exposure to high sugar concentrations.
3Quantity of substance
If high enzyme loading is used during enzymatic hydrolysis, then sugar yield increases, but cost increases and enzyme inhibition by end-products occurs
Solution Approach 1:
The patent maintains continuous useful action by immediately fermenting the produced sugars in the second stage. This continuous removal of end-products (sugars) prevents enzyme inhibition while maintaining high sugar yield, as the fermentation process continuously consumes the sugars as they are produced during saccharification.
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
This approach reduces reaction time, minimizes enzyme usage, and achieves higher ethanol yields of 2.0%-5.0% (W/V) within 48 hours by targeting C5 and C6 sugars sequentially, improving productivity and reducing contamination risks.
Implementation Method 1
enzymatic hydrolysis of biomass
Implementation Method 2
first cellulase enzyme, co-fermenting microorganism, nutrient in the fermentor at 30-37° C. for a period of 16 to 24 hours; adding second cellulase enzyme
Implementation Method 3
preferentially fermenting mainly C5 sugars by incubating the pretreated lignocellulosic biomass of step (i) with first cellulase enzyme, co-fermenting microorganism
Implementation Method 4
incubating the pretreated lignocellulosic biomass of step (i) with first cellulase enzyme, co-fermenting microorganism, nutrient in the fermentor at 30-37° C.
Implementation Method 5
adding second cellulase enzyme to the fermentation broth of step (ii) and increasing the temperature to 45-55° C. for hydrolysis; allowing the fermentation broth of step (iii) to cool to a temperature of 35-38° C.
Data Source
AI summary
The present invention relates to an improved method of second generation ethanol production from a lignocellulosic biomass. The process comprises subjecting a slurry of pre-treated lignocellulosic biomass comprising C5 and C6 sugars in a fermentor; preferentially fermenting mainly C5 sugars by incubating the pretreated lignocellulosic biomass of step (i) with first cellulase enzyme, co-fermenting microorganism, nutrient in the fermentor at 30-37° C. for a period of 16 to 24 hours; adding second cellulase enzyme to the fermentation broth of step (ii) and increasing the temperature to 45-55° C. for hydrolysis; allowing the fermentation broth of step (iii) to cool to a temperature of 35-38° C.; and preferentially fermenting C6 sugars by incubating the broth of step (iv) with a second dose of co-fermenting microorganism for a period of 6-8 hours to obtain ethanol. The process results in high ethanol productivity in shortest duration of time.