Fermentation Process Permeate Recycling for Ethanol Production
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Solution Overview
Problem
Microbial fermentation processes using CO as a substrate face inefficiencies due to co-production of acetate and potential waste disposal issues, along with interruptions in gas supply leading to microorganism hibernation and lag in productivity, and challenges in removing metabolites like acetic acid and 2,3-butanediol from fermentation broth.
Innovation Solution
A method involving microbial fermentation of CO in a bioreactor, where a portion of the fermentation broth is passed through a bleed stream and permeate stream, treated to remove products, and then recycled back to the bioreactor after clarifying modules remove biomass, proteins, and organic or inorganic components, including acids, to maintain optimal conditions and prevent product accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fermentation broth is continuously removed to prevent product accumulation, then ethanol production efficiency is improved, but microorganism hibernation occurs during gas supply interruptions leading to productivity loss
Solution Approach 1:
The patent applies preliminary action by maintaining a reservoir of active microorganisms and pre-treated broth that can quickly replenish the system when gas supply is restored. The continuous cultivation system ensures microorganisms remain metabolically active and ready to resume high-rate ethanol production immediately upon restoration of substrate supply, eliminating the hibernation lag period
2Productivity
If acetate and other metabolites are allowed to accumulate in fermentation broth, then carbon utilization efficiency improves, but waste disposal problems and environmental impact worsen
Solution Approach 1:
The patent implements discarding and recovering by selectively removing accumulated metabolites such as acetate, 2,3-butanediol, and other fermentation by-products from the broth through separation units. These removed metabolites can be further processed or disposed of appropriately, while the clarified broth is recycled back to the bioreactor, thus maintaining carbon utilization efficiency while eliminating waste disposal problems
Solution Approach 2:
The patent converts the harmful effect of metabolite accumulation into a benefit by using the accumulated acetate and other by-products as additional carbon sources or energy substrates for the microorganisms, or by processing them through coupled systems (such as anaerobic digestion or chemical conversion) to produce valuable co-products, thereby transforming waste streams into resources
3Productivity
If treated permeate is recycled back to bioreactor, then resource utilization improves, but product accumulation and inhibition of microbial growth may occur
Solution Approach 1:
The patent applies taking out by using separation units (such as membranes, centrifuges, or adsorption systems) to extract and remove ethanol and other fermentation products from the permeate stream before recycling. This extraction ensures that the recycled broth does not contain inhibitory concentrations of products, thereby maintaining microbial growth rates while still achieving resource utilization through recycling of nutrients and water
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 enhances ethanol production efficiency by maintaining optimal bioreactor conditions, reducing waste, and minimizing the impact of supply interruptions, while allowing for the reuse of treated permeate, thereby improving microbial fermentation productivity and reducing environmental impact.
Implementation Method 1
passing the product depleted stream to a clarifying module wherein at least a portion of one or more components of the product depleted stream selected from the group consisting of biomass, proteins, organic components, or inorganic components is removed
Implementation Method 2
in a bioreactor comprising a culture of one or more microorganisms, fermenting a gaseous substrate comprising CO to produce a fermentation broth comprising one or more products
Data Source
AI summary
This invention relates generally to method for producing products, particularly alcohols, by microbial fermentation. In particular, the invention relates to methods for increasing the efficiency of the fermentation, by providing a method for treating the used fermentation broth to produce a treated permeate which is then passed back to the bioreactor. The invention provides a method whereby at least one treatment step used to treat the permeated, produces a gaseous product which is then used in one or more stages of the fermentation process.