CO2 Partial Pressure Control for Acetogenic Fermentation Purity
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Solution Overview
Problem
Maintaining a balanced population of acetoclastic and acetogenic microorganisms in continuous acetogenic syngas fermentation processes is challenging, particularly in commercial-scale bioreactors, as acetoclastic microorganisms can contaminate the fermentation broth, leading to decreased conversion efficiency and purity issues in producing oxygenated organic compounds.
Innovation Solution
Controlling the partial pressure of carbon dioxide in the bioreactor head space to selectively manage the population of acetoclastic microorganisms, with lower pressures (below 2 kPa) inhibiting their growth and maintaining a desired ratio with acetogenic microorganisms, thereby optimizing the production of oxygenated organic compounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steam cleaning is used to sterilize the bioreactor, then the sterilization effectiveness is improved, but microorganisms may still escape sterilization or contaminate cleaned areas, requiring extended reestablishment time
Solution Approach 1:
The patent applies preliminary action by establishing a controlled CO2 partial pressure environment before and during the fermentation process to prevent acetoclastic microorganism growth. By maintaining CO2 partial pressure below 2 kPa in the head space, the system proactively creates conditions that inhibit contaminant survival, eliminating the need for extensive post-contamination cleanup and reestablishment time.
Solution Approach 2:
The patent implements feedback control by continuously monitoring and adjusting CO2 partial pressure in the bioreactor head space. This feedback mechanism allows real-time control of acetoclastic microorganism population, enabling the system to detect and respond to contamination attempts before they establish, thereby reducing downtime and reestablishment requirements.
2Manufacturing precision
If the bioreactor is taken off-line for contamination removal, then the product purity is improved, but the production capacity is reduced and operating costs increase
Solution Approach 1:
The patent applies self-service by enabling the fermentation system to automatically control and maintain product purity through CO2 partial pressure regulation. The system uses its own operational parameters (CO2 pressure) to inhibit contaminant growth, eliminating the need for external intervention, shutdowns, or manual contamination removal, thereby maintaining continuous production capacity.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting CO2 partial pressure in the head space to control microorganism population. By changing this critical parameter to maintain levels below 2 kPa, the system prevents contamination without requiring physical intervention or production shutdowns, thus preserving both product purity and production capacity simultaneously.
3Productivity
If acetoclastic microorganisms are present in the fermentation broth, then the conversion efficiency is improved, but the product purity decreases due to contamination
Solution Approach 1:
The patent applies local quality by creating a specific CO2 partial pressure environment in the head space that selectively influences microorganism behavior. This localized control of CO2 pressure (maintaining below 2 kPa) creates favorable conditions for acetogenic microorganisms while being adverse to acetoclastic microorganisms, thereby achieving both high conversion efficiency and product purity simultaneously.
Solution Approach 2:
The patent uses parameter changes by regulating CO2 partial pressure to control the competitive balance between acetogenic and acetoclastic microorganisms. By changing the CO2 pressure parameter, the system optimizes conditions to favor acetogenic pathways (improving conversion efficiency) while suppressing acetoclastic contamination (maintaining product purity).
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 method effectively controls the population of acetoclastic microorganisms, minimizing contamination and maintaining high conversion efficiency and product purity over extended periods, without incurring undue operating expenses or loss of bioconversion efficiency.
Implementation Method 1
controlling the partial pressure of carbon dioxide in the bioreactor head space to selectively manage the population of acetoclastic microorganisms, with lower pressures (below 2 kPa) inhibiting their growth
Data Source
AI summary
Methods are disclosed for controlling the population of acetoclastic microorganisms in a process for the bioconversion of gas substrate comprising at least one of CO and a mixture of CO2 and hydrogen to at least one oxygenated organic compound by contact of said gas substrate under acidic, anaerobic fermentation conditions in a bioreactor containing an aqueous fermentation broth having a population of at least one acetogenic microorganism for bioconverting said gas substrate to at least one acetogenic oxygenated organic compound, said fermentation zone defining a head space, said methods comprising continuously or intermittently controlling the partial pressure of carbon dioxide in the head space to provide a desired population ratio of acetoclastic microorganisms to acetogenic microorganisms.