Thin-Layer Microalgae Culture With Mobile Stirring Cycles
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Solution Overview
Problem
Existing microalgae culture systems face high costs due to high power consumption, low algal cell density, and inefficient light utilization, leading to slow growth and high harvesting costs, while also being susceptible to contamination.
Innovation Solution
A method and device for adherent culture of microalgae in a thin liquid layer using mobile mechanical stirring, which includes a subsystem for adherent culture and mechanical stirring, allowing for a thin liquid layer depth of 1-5 cm, periodic suspension and settlement, and mobile mechanical stirring to ensure uniform light exposure and nutrient distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If open type microalgae culture system is used, then structure is simple and operation is convenient, but power consumption is very high and light utilization efficiency is low
Solution Approach 1:
The culture system is segmented into multiple independent plate culture units arranged in series, each with shallow depth (1-5cm) to ensure sufficient light penetration. This segmentation allows natural convection to effectively circulate water through each segment without requiring high-power stirring, resolving the contradiction between simple structure and high power consumption.
Solution Approach 2:
The system utilizes natural convection currents generated by temperature differences and gas exchange to automatically circulate algal cells through the culture plates, eliminating the need for external mechanical stirring. This self-service mechanism maintains structure simplicity while dramatically reducing power consumption compared to traditional open pond systems.
2Illumination intensity
If closed type photo-bioreactor with small diameter is used, then specific illumination area is larger and culture conditions are stable, but device cost is huge and power consumption is high
Solution Approach 1:
Instead of reducing pipe diameter in the traditional closed reactor design, the invention transitions to a plate-based configuration where multiple shallow culture layers are stacked or arranged in series. This dimensional change maintains high specific illumination area while using simple, low-cost plate structures rather than expensive small-diameter tubing.
Solution Approach 2:
The system uses multiple identical plate culture units that can be easily replicated and arranged in series. Each plate is a simple, low-cost component that can be mass-produced, replacing the expensive custom-fabricated small-diameter reactors while achieving similar or better illumination efficiency through the stacked arrangement.
3Stability of the object's composition
If continuous mechanical stirring is applied, then algal cells receive light uniformly, but power consumption is very high and most work is ineffective
Solution Approach 1:
Instead of continuous stirring, the system employs periodic natural convection cycles where water automatically flows upward through illuminated plates and downward through darker regions. This periodic action maintains uniform light distribution over time without the continuous energy input required by mechanical stirrers.
Solution Approach 2:
The invention replaces the mechanical stirring system with a natural convection-based fluid circulation mechanism. Temperature gradients and gas exchange drive the water flow, substituting mechanical energy input with thermodynamic and mass transfer processes that achieve the same mixing and light distribution goals with minimal energy consumption.
4Volume of stationary object
If large water body is used in open type pools, then culture volume is large, but effective transport ratio is only 1/5 or 1/20 and harvesting cost is high
Solution Approach 1:
The large culture volume is segmented into multiple shallow plate units with high surface-area-to-volume ratios. This segmentation ensures that all algal cells remain within the effective light penetration depth, maintaining high effective transport ratio while achieving large total culture volume through the combined capacity of multiple units.
Solution Approach 2:
The system uses dynamic natural convection to continuously circulate water through the plate sequence, ensuring that algal cells dynamically move between illuminated and darker regions. This dynamic circulation maintains high cellular activity and light utilization efficiency throughout the entire culture volume, preventing the stratification and inefficiency seen in static large ponds.
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 reduces power consumption by 80-95%, lowers device costs by 80-90%, increases algal cell density and growth rate, enhances light energy utilization, and minimizes contamination risks, resulting in high-quality, high-density microalgae production with reduced harvesting costs.
Implementation Method 1
a mechanical stirring assembly (21), a moving assembly (22), a guide rail (25), wherein the moving assembly (22) moves on the guide rail (25) to drive the mechanical stirring assembly (21) to stir and suspend the microalgae
Implementation Method 2
have chloroplasts in cells, which can absorb carbon dioxide for photosynthesis and release oxygen
Implementation Method 3
the microalgae stand and gradually settle to bottom after stirring
Data Source
AI summary
A method and a device for adherent culture of microalgae in a thin liquid layer by mobile mechanical stirring, comprising: a subsystem for adherent culture of microalgae in thin liquid layer, for adherent culture of microalgae in a culture solution, comprising a microalgae liquid pool and a culture plate used as a base plate for microalgae seed inoculation, adherent culture, microalgae harvesting, the microalgae liquid pool containing culture solution having a water layer with a depth in a range of 1{tilde over ( )}5 cm, forming a thin liquid layer; and a subsystem for mechanical stirring, comprising a mechanical stirring assembly, a moving assembly, a track member, a power drive assembly, a control assembly, the moving assembly moving on the track member to drive the mechanical stirring assembly to stir and suspend the microalgae, the microalgae standing and gradually settling to the bottom after stirring, realizing adherent culture in suspension and settlement cycle.