Microalgae combine high protein content with efficient cultivation, opening up new opportunities for sustainable food and feed applications. A key factor in developing microorganisms into high-performance production processes is precisely controlled cultivation – with stable process conditions and a reliable gas supply in photobioreactors or fermenters.
Microalgae offer great potential as a sustainable source of protein for food and animal feed. Species that are particularly rich in protein, such as Chlorella and Spirulina—which is often classified as a microalga—can achieve a very high protein content. Depending on the species and cultivation conditions, protein levels of up to about 70% of dry weight are possible. In addition, they contain all essential amino acids.
To convert this biological potential into protein-rich biomass as efficiently as possible, growth conditions must be precisely controlled. In addition to light, temperature, and pH, gas supply plays a central role in this process.
Microalgae are cultivated under controlled conditions in photobioreactors. With the help of light, they use CO₂ as a carbon source to build new biomass. How well this process works depends, among other things, on how much CO₂ is available and how efficiently it is introduced into the culture. Studies show that both the CO₂ concentration in the inlet and the gas flow rate influence mass transfer and, consequently, biomass productivity.
The gas delivery system fulfills several functions: It supplies the culture with CO₂, supports mass transfer, and can help remove excess oxygen from the reactor. For research and process development, it is therefore important to precisely adjust the gas flows and maintain their reproducibility.
Especially in small photobioreactors and laboratory setups, even slight changes in the gas supply can affect cultivation conditions. To ensure comparable experimental results, CO₂ and air flows must therefore be reliably measured and controlled.
Conventional volumetric flow meters can also be affected by pressure and temperature. Thermal mass flow meters and mass flow controllers, on the other hand, directly measure the mass flow rate or a gas flow rate referenced to standard conditions and are therefore particularly well–suited for processes that require reproducible gas dosing.
This is especially important in research: Only when process conditions remain as constant as possible from experiment to experiment can changes in growth, biomass production, or protein content be meaningfully assessed.
Precise Gas Control with Vögtlin Instruments
For controlled gas supply, Vögtlin offers various solutions for measuring and controlling CO₂, air, and other process gases.
The red-y smart series is suitable for the precise measurement and automatic control of gas flows. The devices use MEMS sensor technology and offer both analog and digital interfaces. Depending on the model, accuracies of up to ±0.3% of the full scale value plus ±0.5% of the measured value are possible.
The red–y compact series is ideal for mobile measurement tasks or applications where no external power supply is available. The battery–powered mass flow meter is available for CO₂ and O₂, among other gases, and can be optionally equipped with a manual control valve.
For higher flow rates and applications where additional process parameters need to be measured in addition to flow, the d·flux multi series is available as a mass flow meter or controller. It offers modern digital interfaces and measurement ranges up to 1,400 ln/min.
In microalgae cultivation, it is not merely a matter of supplying CO₂. What is crucial is how precisely and reproducibly it is fed into the process.
Precise mass flow measurement and control provide the necessary foundation for this. Researchers can set defined cultivation conditions, better compare experiments, and specifically investigate the influence of various process parameters.
In this way, a biological process becomes a controllable development process—and microalgae may become an important source of protein for the nutrition of the future.
