Photosynthesis Layer Bicarbonate Diffusion for High-Density Culture
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In photo-bioreactors, maintaining adequate carbon supply and preventing pH gradients at high cell densities is challenging due to carbon dioxide depletion and light limitation, especially in thin photosynthesis layers, which can lead to substrate deficiency zones and cell death.
Innovation Solution
A process involving a photosynthesis layer with a bicarbonate concentration of at least 10 mM, maintained by an initial high concentration in the medium or through diffusion from a separate carbon storage medium, and using a membrane-permeable substrate to prevent pH increase and ensure carbon availability, without stirring or gas passage, allowing for efficient carbon distribution and light penetration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high biomass concentration is used in photo-bioreactors, then productivity increases, but carbon dioxide depletion zones and light deficiency occur leading to cell death
Solution Approach 1:
The system is segmented into two distinct compartments: a photosynthesis compartment containing the microorganism culture and a reservoir compartment containing concentrated bicarbonate solution. These compartments are separated by a gas-permeable membrane that allows selective diffusion of carbon dioxide, enabling high biomass concentration while preventing substrate depletion through the membrane-mediated supply interface
Solution Approach 2:
A gas-permeable membrane acts as an intermediary between the reservoir compartment and the photosynthesis compartment. This membrane selectively allows carbon dioxide to diffuse from the concentrated bicarbonate solution into the culture medium, providing continuous carbon supply to high-density cultures without direct mixing or contamination
2Quantity of substance
If carbon dioxide is supplied by introducing air or carbon dioxide-air mixture into cell suspension, then carbon supply is provided, but carbon dioxide depletion zones form at high biomass concentrations
Solution Approach 1:
The carbon dioxide supply system is extracted from the bulk liquid phase and relocated to a separate reservoir compartment. Carbon dioxide is generated in the reservoir from concentrated bicarbonate and delivered through the membrane interface, eliminating the formation of depletion zones that occur during direct aeration of the culture
3Quantity of substance
If bicarbonate concentration is increased to more than 200 mmol L−1 to support high biomass growth, then carbon stock is sufficient, but many cultures die off due to toxicity
Solution Approach 1:
The system separates the high-concentration bicarbonate solution into a distinct reservoir compartment isolated from the culture by a gas-permeable membrane. This segmentation allows the use of toxic concentrations (200 mmol L−1 or higher) in the reservoir to provide sufficient carbon stock, while the membrane prevents direct contact between the toxic bicarbonate and the sensitive microorganism culture
Solution Approach 2:
The gas-permeable membrane serves as an intermediary that permits carbon dioxide diffusion from the high-concentration bicarbonate reservoir to the culture while blocking the passage of toxic bicarbonate ions and other harmful substances, enabling safe delivery of high carbon flux
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 enables high rates of photosynthesis at high cell densities without energy-consuming gas injection, preventing substrate depletion and pH toxicity, and supports stable growth of photoautotrophic microorganisms by maintaining optimal bicarbonate levels and light distribution.
Implementation Method 1
continuous delivery of a carbon substrate for photosynthesis chosen from the group comprising carbon dioxide and bicarbonate ions from a cell-free carbon storage medium (4) that is located outside of the photosynthesis medium by diffusion through a membrane that is permeable to the photosynthesis substrate
Implementation Method 2
photoautotrophic microorganisms suspended therein... exposure of the photosynthesis layer (2) to the light... rates of photosynthesis... production of oxygen, biomass or organic material by the photoautotrophic microorganisms
Implementation Method 3
located within a closed space with an outer border (1) acting as barrier for gas diffusion
Data Source
AI summary
The invention relates to a method for cultivating photoautotrophic micro-organisms, comprising the following steps: provision of a photosynthesis layer, which contains a photosynthesis medium and photoautotrophic micro-organisms suspended therein, in a closed accommodation space having a gas-diffusion-inhibiting outer boundary, wherein the photosynthesis layer has an average thickness of no more than 10 mm; exposure of the photosynthesis layer without eddying or feeding through a gas in the photosynthesis medium while limiting the diffusive gas exchange of the accommodation space by the environment, wherein the supply of micro-organisms in the photosynthesis medium with hydrogen carbonate ions is maintained by storing hydrogen carbonate ions in the photosynthesis medium and/or providing a photosynthesis substrate in the form of carbon dioxide and hydrogen carbonate from a cell-free carbon storage medium outside the photosynthesis layer; and conducting a gas formed during photosynthesis out of the accommodation space.