Fermentation Sulfur Control for Ethanol Production
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current microbial fermentation processes for producing ethanol from carbon monoxide often result in inefficient ethanol production due to co-production of acetate and potential waste disposal issues, along with challenges in maintaining optimal sulfur availability and redox conditions, leading to reduced productivity and increased costs.
Innovation Solution
A method involving the use of a bioreactor with a culture of acetogenic carboxydotrophic microorganisms, where a sulfur source such as sulphurous acid or its derivatives is provided, converted to H2S, and maintained at concentrations between 1ppm and 100ppm to optimize ethanol production, utilizing waste sulfur sources from industrial processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional yeast-based fermentation processes are used to produce ethanol from carbohydrate feed stocks, then ethanol production is achieved, but the cost is influenced by the value of feed stocks as human food or animal feed and cultivation is not economically sustainable in all geographies
Solution Approach 1:
The invention changes the carbon source parameter from carbohydrate feed stocks to carbon monoxide gas, and changes the microorganism parameter from traditional yeast to carboxydotrophic microorganisms capable of utilizing CO. This fundamental parameter change enables the use of industrial waste gas as feedstock, eliminating the economic sustainability issue associated with food crop cultivation while maintaining ethanol production capability.
Solution Approach 2:
The invention converts carbon monoxide, an industrial waste product that is harmful to the environment when released into the atmosphere, into a valuable feedstock for ethanol production. By using CO from steel industry waste gas or other industrial sources as the carbon source, the process transforms an environmental pollutant into an economically beneficial resource, simultaneously producing ethanol and reducing greenhouse gas emissions.
2Ease of manufacture
If carboxydotrophic microorganisms are used to ferment CO into ethanol, then lower cost carbon resources are utilized, but acetate and/or acetic acid are co-produced reducing production efficiency and creating waste disposal problems
Solution Approach 1:
The invention changes the chemical environment parameters by adding specific metal ions (nickel, cobalt, manganese, zinc) and controlling the redox potential and pH levels. These parameter changes create optimal conditions for the microorganisms to channel carbon flux toward ethanol production rather than acetate production, thereby improving ethanol production efficiency while maintaining the use of low-cost CO feedstock.
Solution Approach 2:
The invention implements monitoring and control of key parameters including redox potential, pH, and metal ion concentrations during the fermentation process. By continuously monitoring these parameters and making adjustments as needed, the process maintains optimal conditions for high ethanol production efficiency and minimizes acetate by-product formation throughout the fermentation operation.
3Reliability
If sulfur sources are added to the nutrient medium to maintain optimal redox conditions, then microbial growth and product formation are improved, but excessive sulfur may be toxic to microorganisms and reduce productivity
Solution Approach 1:
The invention changes the sulfur source from traditional forms to sulfur dioxide or sulfite salts, and carefully controls the concentration and delivery rate. By adjusting these parameters and adding sulfur compounds gradually, the process maintains optimal redox conditions necessary for carboxydotrophic fermentation while preventing toxic accumulation that would harm microbial productivity.
Solution Approach 2:
The invention implements periodic or controlled-rate addition of sulfur sources during the fermentation process rather than single bulk addition. This periodic action allows the sulfur to be gradually incorporated into the system, maintaining stable redox conditions without causing sudden toxic effects on the microorganisms, thereby preserving high productivity throughout the process.
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, reduces waste, and lowers operational costs by ensuring consistent sulfur availability and optimal redox conditions, effectively addressing the limitations of traditional fermentation methods.
Implementation Method 1
converting the sulphur source to H2S in a headspace of the bioreactor
Implementation Method 2
anaerobically fermenting the substrate to produce one or more products selected from the group comprising alcohols, acids and mixtures thereof
Data Source
Figure 1~2
Figure 3~4
AI summary
This invention relates generally to methods for increasing the efficiency of microbial growth and production of products, such as alcohols and acids by microbial fermentation of substrates containing carbon monoxide. More particularly the invention relates to the provision of an alternative sulphur source to a liquid nutrient medium, such that sulphur is available to one or more microorganisms of the fermentation.