Bioreactor Methanation With Cell Retention and Metabolic Water Removal
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Solution Overview
Problem
The challenge of maintaining a stable and efficient biogenic methane production process is hindered by the continuous discharge of metabolic water, which dilutes essential medium components and requires frequent replenishment, increasing operational costs and inefficiencies.
Innovation Solution
A method involving cell retention conditions in a bioreactor to maintain methanogenic microorganisms, coupled with continuous removal of metabolic water and controlled nutrient supply, particularly reducing nitrogen source input, to enhance methane production efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If metabolic water is continuously discharged to maintain constant liquid level, then bioreactor overflow is prevented, but medium components and nutrients are lost
Solution Approach 1:
The patent implements a medium recovery system that captures the discharged metabolic water containing dissolved nutrients and minerals, and returns it to the bioreactor. This resolves the contradiction by discarding the harmful effect (overflow risk) while recovering and reusing the valuable nutrients that would otherwise be lost, thereby maintaining both liquid level stability and nutrient availability.
2Productivity
If concentrated medium stock solutions are continuously added to compensate for nutrient dilution, then methanation rate is maintained, but operational costs increase
Solution Approach 1:
Instead of discarding the metabolic water and adding fresh concentrated medium, the system recovers the nutrients from the discharged water and returns it to the bioreactor. This eliminates the need for continuous addition of expensive concentrated medium stock solutions while maintaining the methanation rate, thereby resolving the contradiction between productivity and operational costs.
Solution Approach 2:
The medium recovery system enables the bioreactor to self-regenerate its nutrient supply by recycling its own metabolic discharge. The system essentially serves itself by converting waste metabolic water back into a useful nutrient source, reducing dependence on external medium additions and lowering operational costs.
3Productivity
If cell retention conditions are applied, then methane production efficiency increases, but system complexity increases
Solution Approach 1:
The patent introduces a membrane as an intermediary element that selectively retains methanogenic cells while allowing metabolic water and dissolved nutrients to pass through. This simple membrane-based approach achieves cell retention and improved methane production efficiency without requiring complex cell separation or recycling systems, thereby resolving the contradiction between productivity and system complexity.
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 method achieves a 30-50% increase in methane production efficiency by retaining cells within the bioreactor, reducing nutrient losses, and optimizing nutrient supply, thereby lowering operational costs and maintaining a stable methanation rate.
Implementation Method 1
Within a bioreactor, a culture of hydrogen using methanogenic microorganisms catalyses the methanation reaction as follows: CO2+4H2→CH4+2H2O
Implementation Method 2
iv. continuously removing metabolic water in the culture medium from the bioreactor
Implementation Method 3
A well-known technique is distillation, which would allow to remove excess water by evaporation.
Data Source
AI summary
The present invention refers to a method to convert H2 and CO2 into methane by methanogenic microorganisms in a bioreactor in a continuous production process for methane enriched gas compositions, while culturing the methanogenic microorganisms under cell retention conditions and continuously removing metabolic water in the cell culture medium.