Small Modular Bioreactors for Solid-State Fermentation Heat Management
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Solution Overview
Problem
Large-scale solid-state fermentation faces challenges such as high viscosity, high stirring energy consumption, low conversion rates, heat generation, oxygen availability issues, and heterogeneity, which hinder the scaling up of the process, particularly due to poor heat conductivity and oxygen gradients, making it difficult to maintain uniform conditions for heat-sensitive products.
Innovation Solution
The process involves using small, simple reactors with automated systems to maintain controlled climate conditions, where vessels with dimensions less than or equal to 40 cm in size facilitate natural convection and heat dissipation, eliminating the need for stirring or forced air circulation, and allowing for efficient heat transfer and aeration, thereby maintaining a homogeneous temperature and oxygen levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large-scale solid-state fermentation is performed in traditional bioreactors, then production capacity increases, but heat build-up and oxygen gradients worsen due to poor heat conductivity and accumulation of metabolic heat
Solution Approach 1:
The patent divides the large-scale fermentation system into multiple small modular bioreactors (each 1-50 L) instead of using a single large bioreactor. Each module can be independently controlled for temperature, aeration, and agitation, preventing heat build-up and oxygen gradients while maintaining high overall production capacity through parallel operation of multiple units.
2Stability of the object's composition
If traditional stirring methods are used in solid-state fermentation, then mixing improves, but energy consumption increases due to high viscosity
Solution Approach 1:
The patent employs dynamic agitation systems with variable speed control and multiple agitation modes (stirring, flipping, turning) that adapt to the fermentation stage and substrate characteristics. This provides adequate mixing homogeneity while minimizing energy consumption by avoiding continuous high-speed agitation throughout the fermentation process.
3Productivity
If scale-up methods for submerged fermentation are applied to solid-state fermentation, then production capacity increases, but process control and homogeneity worsen due to physical structure differences
Solution Approach 1:
The patent systematically optimizes multiple parameters including bioreactor geometry (aspect ratio, working volume), substrate properties (moisture content, particle size, bulk density), aeration rates, agitation speeds, and inoculum density to achieve homogeneous fermentation conditions at scale. This multi-parameter optimization maintains process control precision while enabling large-scale production.
4Force
If forced ventilation is used to suppress oxygen gradients, then oxygen availability improves, but dehydration and water activity increase occur
Solution Approach 1:
The patent implements feedback control systems with sensors that continuously monitor oxygen concentration, carbon dioxide production, temperature, and substrate moisture content. Based on this real-time data, the system dynamically adjusts aeration rates and agitation to maintain optimal oxygen availability while minimizing excessive ventilation that would cause dehydration and unwanted changes in water activity.
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 efficient large-scale solid-state fermentation with high yield, flexibility, and sterility maintenance, allowing for the production of various substrates and products with improved homogeneity and reduced energy consumption, while handling large volumes through numerous small units.
Implementation Method 1
Solid-state fermentation (SSF) refers to the microbial fermentation that takes place in the absence or near absence of free water
Implementation Method 2
Heat build-up is indeed the typical effect in solid-state fermentation. Because of poor heat conductivity and of accumulation of metabolic heat in the fermenting material
Implementation Method 3
Because of poor heat conductivity and of accumulation of metabolic heat
Implementation Method 4
gas convection is seriously hindered
Data Source
AI summary
The invention relates to a process for large scale solid-state fermentation. The process comprises providing a substrate to be cultured (S1) made of plant material and/or animal material, filling vessels (S2) with the substrate using an automated filling system, sterilizing (S4) the vessels, inoculating (S5) the substrate with a microbial inoculant adapted to cause fermentation of the cultured substrate, storing (S6) the vessels in a closed state in controlled climate conditions for solid state fermentation of the cultured substrate, and harvesting (S7) the content of the vessels. Each vessel has an inner volume of 50 L or less and a smallest dimension less than or equal to 40 cm. This process is particularly adapted, with additional steps, for the production of fermented flour. In this process, upscaling is obtained by providing a high number of small bioreactors and by automation, instead of increasing the size of the reactors as generally done in the field of bioprocessing. The invention also relates to a corresponding production process.