Photobioreactor pH Control via Bicarbonate Buffering
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Solution Overview
Problem
Tubular photobioreactors face challenges in maintaining pH control and mass transfer efficiency, especially at high biomass concentrations and light intensities, leading to gradients and increased energy costs due to mechanical stress from aeration and pumping.
Innovation Solution
Incorporating a bicarbonate buffer system with bicarbonate ions and/or carbonate ions in the culture medium, along with a CO2-enriched gas phase as slug flow or plug flow, to enhance pH buffering and mass transfer, while reducing fluid velocities and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If aeration and pumping are increased to maintain pH control and mass transfer at high biomass concentrations, then productivity is improved, but energy consumption and mechanical stress increase
Solution Approach 1:
The patent changes the chemical composition parameters of the culture medium by adding bicarbonate buffer system (2-10 mM NaHCO3) and adjusting CO2 concentration in the gas phase (0.2-10 vol.-%). This chemical parameter change enhances pH buffering capacity and mass transfer efficiency, allowing the system to maintain productivity at high biomass concentrations without increasing aeration and pumping energy input
2Productivity
If tube length is increased to improve productivity, then volumetric productivity is improved, but pressure loss increases and connections become more complex
Solution Approach 1:
The patent changes the fluid dynamic parameters by reducing fluid velocity in the tubes and lowering operating pressure. This allows extended tube lengths (100-1000 meters) to be used for improved productivity while minimizing pressure loss, enabling the use of simple push-fit connections without complex sealing requirements
3Stability of the object's composition
If bicarbonate buffer system is added to enhance pH buffering, then pH control is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent implements a self-regulating pH control system where the bicarbonate buffer system (2-10 mM NaHCO3) in the culture medium automatically buffers pH changes through the equilibrium reaction CO2 + H2O ⇌ H2CO3 ⇌ H+ + HCO3-. The system self-adjusts pH without requiring external pH meters, sensors, or active control mechanisms, thereby improving pH stability while avoiding increased device 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
This approach improves pH control and mass transfer efficiency, allowing for higher volumetric productivities, reduced energy costs, and prevention of fouling, enabling longer tube lengths and lower pressure systems with simpler connections, thus enhancing the economic viability of photobioreactor systems.
Implementation Method 1
The liquid culture medium contains a bicarbonate buffer system containing bicarbonate ions and/or carbonate ions
Implementation Method 2
CO2 is consumed by the suspended microorganism, while O2 is produced. The withdrawal of CO2 by the phototrophic microorganisms from the liquid phase causes an increase of the pH of the liquid phase
Implementation Method 3
When illuminated, photosynthesis occurs in the phototrophic microorganisms, enabling the production of carbohydrates from CO2 and H2O
Implementation Method 4
In the dark photosynthesis will not occur. Due to respiration O2 will be consumed by the suspended microorganism, while CO2 is produced
Implementation Method 5
a gas phase containing at least 0.2 vol.-% CO2 is introduced into the culture medium as slug flow or plug flow
Implementation Method 6
a gas phase containing at least 0.2 vol.-% CO2 is introduced into the culture medium as slug flow or plug flow
Implementation Method 7
a gas phase containing at least 0.2 vol.-% CO2 is introduced into the culture medium as slug flow or plug flow
Data Source
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AI summary
The invention relates to a method for the cultivation of microorganisms, especially phototrophic microorganisms in a bioreactor or photobioreactor, wherein bicarbonate ions and carbonate ions or a cation surplus concentration in the culture medium is added. The invention also relates to a tubular bioreactor and photobioreactor wherein the method can be achieved and the use of bioreactors, photobioreactors, tubes and pipes in a method according to the present invention.