Fermentation Medium Selenium Reduction for Ethanol Production
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Solution Overview
Problem
Current processes for fermenting CO-containing gaseous substrates to produce ethanol often require high levels of selenium, which increases operational costs and is not cost-effective at a commercial scale, while maintaining high ethanol productivity.
Innovation Solution
A fermentation process and medium are developed that reduce selenium levels in cell biomass to 1 ppm or less, maintaining a specific space time yield of at least 1 gram of ethanol/(L·day·gram cells) by optimizing nutrient concentrations and removing or reducing selenium from the medium, thereby achieving significant cost savings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high levels of selenium are included in the fermentation medium, then ethanol productivity is maintained, but operational costs increase significantly
Solution Approach 1:
The patent changes the selenium concentration parameter in the fermentation medium from traditional high levels (e.g., 10-100 µM) to significantly reduced levels (e.g., 0.1-10 µM). This parameter change resolves the contradiction by demonstrating that lower selenium levels can maintain ethanol productivity while reducing operational costs and selenium quantity in the medium.
Solution Approach 2:
The patent employs a disposable, optimized fermentation medium formulation that eliminates the need for high selenium content. By using a carefully balanced medium composition with reduced selenium, the process achieves cost-effective operation without requiring expensive selenium supplementation, thereby resolving the contradiction between productivity and selenium quantity.
2Quantity of substance
If selenium is removed or reduced from the medium, then operational costs decrease, but ethanol productivity may be compromised
Solution Approach 1:
The patent identifies and optimizes multiple medium parameters simultaneously, not just selenium level. By adjusting concentrations of carbon sources, nitrogen sources, vitamins, and other trace elements in combination with reduced selenium, the system maintains ethanol productivity while achieving lower selenium levels. This multi-parameter optimization resolves the contradiction between selenium reduction and productivity maintenance.
Solution Approach 2:
The patent introduces optimized medium composition as an intermediary system that compensates for reduced selenium. The balanced formulation of other nutrients and growth factors acts as a mediator that maintains cellular metabolism and ethanol production efficiency even with lower selenium availability, thereby resolving the contradiction.
3Quantity of substance
If traditional medium components are eliminated or reduced, then medium cost decreases, but fermentation performance may deteriorate
Solution Approach 1:
The patent extracts and removes unnecessary or excessive medium components from traditional formulations. By eliminating redundant nutrients and optimizing the concentration of essential components, the process achieves cost-effective medium composition while maintaining fermentation performance. This selective removal resolves the contradiction between medium simplification and productivity maintenance.
Solution Approach 2:
The patent systematically optimizes the concentration parameters of multiple medium components including carbon sources, nitrogen sources, phosphates, sulfates, and trace elements. By adjusting these parameters to optimal levels rather than using traditional high concentrations, the process reduces medium cost while maintaining or improving ethanol productivity, thereby resolving the contradiction.
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 process achieves high ethanol productivity with reduced selenium levels in cell biomass, providing a cost-effective solution for commercial-scale ethanol production while maintaining high space time yield and cell density.
Implementation Method 1
Anaerobic microorganisms can produce ethanol from carbon monoxide (CO) through fermentation of gaseous substrates
Implementation Method 2
The Wood-Ljungdahl pathway is well known in the art and includes reactions which can be separated into two branches: (1) methyl branch and (2) carbonyl branch
Implementation Method 3
Enzymes catalyze reactions in the Wood-Ljungdahl pathway and those enzyme require various elements for optimal functionality
Data Source
AI summary
A process for fermenting syngas and a fermentation medium provides high ethanol productivity while removing medium components that were previously thought to be essential. The process is effective for providing a specific STY of at least about 1 gram of ethanol/(L·day·gram cells) and for providing a selenium content in cell biomass exiting the fermentation of about 1 ppm or less.