Fermentation Bioreactor Agitation and Gas Flow Control
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Solution Overview
Problem
Current methods for microbial fermentation of gaseous substrates comprising carbon monoxide and hydrogen face challenges in rapidly increasing cell density, which is crucial for high production rates of chemicals like alcohols, often resulting in inefficient start-up processes due to rapid changes in gas rate and agitation after inoculation.
Innovation Solution
A method involving the fermentation of a gaseous substrate comprising carbon monoxide and hydrogen in an aqueous medium with anaerobic acetogenic microorganisms, where the agitation speed and gas flow are adjusted within specific ranges to optimize CO and H2 conversion differences, thereby increasing cell density effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If batch inoculum from stock culture is used to ensure healthy inoculum free from contaminants, then reliability is improved, but productivity deteriorates due to low cell density
Solution Approach 1:
The patent applies preliminary action by pre-adapting the inoculum to continuous culture conditions in a seed bioreactor before transferring to the production bioreactor. This preliminary adaptation phase allows cells to acclimate to the continuous operation mode, ensuring reliable contamination-free culture while building sufficient cell density to achieve high productivity in the subsequent production phase.
Solution Approach 2:
The patent segments the fermentation process into distinct phases: a seed bioreactor phase for inoculum preparation and adaptation, and a production bioreactor phase for high-density cell cultivation and product formation. This segmentation allows each phase to be optimized independently - the seed phase ensures purity and adaptation, while the production phase maximizes cell density and productivity.
2Productivity
If gas rate and agitation rate are pushed upward rapidly after inoculation to increase production rate, then productivity is improved, but reliability deteriorates due to unsuccessful start-up
Solution Approach 1:
The patent applies dynamics by implementing a gradual, stepwise increase in gas rate and agitation rate rather than sudden changes. The system dynamically adjusts operating parameters over time, allowing the microbial culture to adapt progressively to increased demands on substrate consumption and product formation, thereby ensuring reliable start-up while achieving high productivity.
Solution Approach 2:
The patent employs periodic action through controlled, incremental increases in gas flow rate and agitation speed at defined intervals during the start-up phase. This periodic adjustment pattern allows the system to build up production rate systematically while monitoring for signs of stress or contamination, ensuring reliable transition to high-productivity operation.
3Productivity
If cell-recycle is used to increase cell density, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent applies self-service by designing the continuous culture system to maintain high cell density through inherent process dynamics rather than complex external cell recycling equipment. The continuous feed of substrate and removal of products creates a self-sustaining environment where cells naturally accumulate to high densities, achieving high productivity without the need for additional centrifuges, filters, or recycling pumps.
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 allows for a faster and more controlled increase in cell density, enhancing the production rates of alcohols by maintaining optimal conversion rates of CO and H2, leading to improved fermentation efficiency and productivity.
Implementation Method 1
fermenting a gaseous substrate comprising carbon monoxide (CO) and hydrogen (H2) in an aqueous medium in a bioreactor said aqueous medium comprising one or more anaerobic acetogenic microorganisms
Data Source
Figure 1
AI summary
A method of gaseous substrate fermentation comprising: adding gaseous substrate comprising carbon monoxide (CO) and hydrogen (H2) into an aqueous medium in a bioreactor; said method comprising measuring conversion of CO; measuring conversion of H2; increasing flow of gaseous substrate by a preselected flow factor; wherein agitation comprises greater than or equal to target agitation rate.