Porous Floating Support Structures for Microalgae Gas Transfer
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Solution Overview
Problem
Current methods for cultivating microalgae and cyanobacteria, such as open raceway-ponds and bioreactors, face challenges with sub-optimal gas transfer, high costs, and limited growth rates and densities due to inefficient mass transfer of gases between gaseous and liquid media.
Innovation Solution
A system and method involving movable members with surfaces that periodically expose to both gaseous and liquid media, creating a renewing wetted surface to enhance gas mass transfer, combined with the use of nanobubbles to increase interface area and efficiency, and a rotatable design to improve mixing and light scattering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If open raceway-ponds are used for microalgae cultivation, then capital costs are reduced, but gas transfer efficiency and culture density are sub-optimal
Solution Approach 1:
The patent employs porous floating support structures that provide extensive surface area for gas-liquid mass transfer. The porous material allows efficient diffusion of gases (CO2, O2) between the atmosphere and liquid culture medium while maintaining structural buoyancy, thereby achieving high gas transfer efficiency without the need for expensive closed bioreactor systems
Solution Approach 2:
The invention transitions from traditional two-dimensional surface pond cultivation to three-dimensional vertical structures. The floating support structures extend into the water column, creating multiple interfaces for gas exchange and enabling volumetric culture density enhancement while maintaining open-system simplicity
2Productivity
If column photobioreactors with air sparging systems are used, then culture density and yields are improved, but capital costs and operating costs increase
Solution Approach 1:
The floating support structures are self-buoyant and automatically position themselves at the liquid surface, requiring no complex installation infrastructure. The structures self-regulate their position and provide continuous gas-liquid interface without requiring expensive pumps, sparging systems, or controlled environment equipment, thereby achieving high culture density at low capital cost
Solution Approach 2:
The floating support structures serve multiple functions simultaneously: providing structural buoyancy, creating gas-liquid mass transfer interfaces, supporting lighting elements, and enabling culture containment. This multi-functionality eliminates the need for separate expensive components found in conventional bioreactors
3Productivity
If tubular photobioreactors are used, then culture density is improved, but maintenance costs and energy consumption increase
Solution Approach 1:
The floating support structures are designed to be dynamically adaptable, flexing and moving with water conditions rather than being rigid fixed structures. This dynamic design prevents stress concentration and structural failure, reducing maintenance requirements while maintaining effective culture density through continuous motion that prevents biofouling
4Productivity
If attachment culture mode is used, then culture density is improved, but light penetration and nutrient exchange are limited
Solution Approach 1:
The floating support structures divide the culture volume into multiple segmented compartments or zones, each with its own gas-liquid interface. This segmentation ensures that all culture regions have direct access to atmospheric gases and light, preventing the light penetration and nutrient exchange limitations that occur in dense attachment cultures
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 increases gas solubilization and exchange rates, leading to higher reaction rates, product yields, and improved growth rates and densities of microorganisms, while reducing operational costs and energy consumption.
Implementation Method 1
enhancing mass transfer of the gas between the liquid medium and the gaseous medium
Implementation Method 2
combined with the use of nanobubbles to increase interface area and efficiency
Data Source
AI summary
The present invention provides a system and a method for enhancing mass transfer of a gas between a gaseous medium and a liquid medium in reactions involving such a mass transfer, and for effective mixing of the liquid medium.