In the field of modern bioengineering, bio-solid fermentation reactors play a key role. These devices are specially designed to cultivate various microorganisms or other organisms, which use solid substrates as a medium for growth and metabolism. Compared with liquid fermentation reactors that rely on liquid culture media, solid fermenters operate on a completely different principle. They mainly rely on solid substrates for cultivation, so they have higher adaptability and efficiency for certain specific microbial populations, such as fungi, yeasts and some specialized bacteria.

This type of reactor has a wide range of applications, from the fermented food industry to biofuel production, to the extraction of active substances in pharmaceutical processes. By precisely controlling fermentation conditions such as temperature, humidity, pH and nutrients, researchers can study and optimize the genetic characteristics and physiological functions of microorganisms. In addition, solid fermentation also provides an environmentally friendly and efficient method for the production of enzyme preparations, vaccines and biochemicals. In this type of reactor, the use of solid raw materials not only reduces the impact on the environment, but also reduces waste and improves the efficiency of resource utilization. In short, solid fermentation reactors are one of the important tools for biotechnology innovation and sustainable development.

Solid-state fermentation tanks can provide microorganisms with suitable conditions such as temperature, humidity, gas exchange and matrix structure, so as to achieve efficient utilization of microbial growth, metabolism and target products. On this basis, a new efficient and stable fermentation process is proposed. The working principle of solid fermentation tanks is mainly based on the growth and metabolism of microorganisms on solid substrates. By providing microorganisms with appropriate nutrients, oxygen and humidity under a controlled environment, they are promoted to carry out fermentation reactions. The specific working principle can be divided into the following steps:

Substrate preparation

The substrate in the solid fermentation tank is generally some nutrient-rich organic matter, such as grains, corn cobs, sawdust, rice husks, etc. These solid materials provide microorganisms with carbon sources, nitrogen sources, minerals, etc. required for growth. The selection and pretreatment of the substrate (such as moisture adjustment, sterilization, etc.) are very critical and affect the fermentation efficiency and product quality.

Inoculation

A certain amount of microorganisms (such as fungi, yeast or certain bacteria) are inoculated on the solid substrate in the fermentation tank. Inoculation is usually carried out by mixing the microorganisms with the culture solution or directly spreading them on the solid substrate.

Temperature and humidity control

The growth and metabolic activities of microorganisms need to be carried out at specific temperature and humidity. Solid fermentation tanks are usually equipped with temperature and humidity control systems to ensure that the environmental conditions are always in the optimal range for microbial growth throughout the fermentation process. Generally speaking, the temperature will be maintained between 25 and 40°C, and the humidity will be maintained between 60% and 80%, depending on the type of microorganism being fermented.

Oxygen supply and gas exchange

Although solid fermentation uses solid substrates as carriers, microorganisms still need oxygen for respiration, especially aerobic microorganisms. In a closed fermentation tank, oxygen enters through the gas circulation system to ensure the respiration needs of microorganisms. At the same time, waste gases such as carbon dioxide need to be removed to avoid excessive carbon dioxide concentration in the environment inhibiting the growth of microorganisms.

Stirring and turning

In some solid fermentation tanks, the stirring or turning device will work regularly to ensure that the gas exchange, temperature and humidity in the solid substrate are evenly distributed. This can avoid the situation of substrate agglomeration, drying or uneven fermentation. Turning can also accelerate the contact between microorganisms and the substrate and improve the fermentation efficiency.

Fermentation process and product generation

Microorganisms metabolize in the solid substrate, decompose the organic matter in the substrate, and produce a series of metabolites, such as enzymes, acids, gases, antibiotics, etc. As fermentation progresses, the solid matrix is gradually consumed, and the metabolites of microorganisms accumulate. When fermentation reaches a certain level, the product can be harvested.

Monitoring and control

Modern solid fermentation tanks are usually equipped with an automated monitoring system to detect key parameters in the reaction process (such as temperature, humidity, oxygen concentration, pH value, etc.) in real time, and adjust various conditions through the control system to ensure the stability of the fermentation process and the high quality of the product.

Different types of solid fermentation tanks have their own characteristics in design and application.

Layered fermentation tank

Layered fermentation tanks are usually composed of multiple horizontally placed layers (trays) on which solid substrates are distributed. Each layer has an appropriate ventilation and gas exchange system, usually through the flow of air or gas to ensure the growth of microorganisms.

Suitable for large-scale production, suitable for processing a large amount of solid substrates, and often used in industrial production. Simple structure, relatively simple design, easy to operate and maintain. Uniform air distribution, good gas ventilation system ensures uniform oxygen supply to each layer of fermentation substrate. Suitable for fungal fermentation, often used in solid substrate fermentation process, especially suitable for fungal growth. However, due to its large footprint, the layered fermentation tank occupies a large space due to the need for multiple layers. The operation is relatively cumbersome, and the operation is relatively cumbersome due to the need to regularly check and turn over the substrate. Layered fermentation tanks are usually used for large-scale fermentation of microorganisms such as fungi and yeast, especially in environments where multiple layers of substrates need to be stacked.

Rotary barrel fermentation tank

The rotary barrel fermentation tank is a solid fermentation tank that uses a horizontal or inclined rotary barrel. The barrel is filled with solid matrix, and as the barrel rotates, the matrix is constantly turned over in the barrel, ensuring uniform mixing of the matrix and gas exchange. It has the advantages of uniform mixing, and the rotation of the barrel ensures uniform distribution of the matrix and sufficient exchange of oxygen. Save space. Compared with layered fermenters, rotary barrel fermenters occupy less space and are suitable for compact spaces. Suitable for small and medium-sized production, suitable for production needs that are not as large as layered fermenters. However, due to its high energy consumption, the rotation of the barrel requires a certain amount of power support, and the energy consumption is relatively high. Substrate loss. Due to the turning, some fragile substrates may be lost or mechanically damaged. Rotary barrel fermenters are widely used in small and medium-sized solid fermentation, such as yeast fermentation, fungal culture, etc., and are suitable for occasions that do not require too many hierarchical structures.

Moving bed fermenter

The moving bed fermenter is characterized by a layer of freely movable solid bed inside, usually composed of fillers with a certain shape and structure (such as particles, ceramic balls, etc.). Microorganisms grow on these fillers, and as the bed moves, the solid matrix is constantly turned over to achieve a uniform supply of oxygen and nutrients. Improve mass transfer efficiency. Due to the movement of the bed, the transfer efficiency of gas and liquid is higher, and oxygen and other nutrients can be better supplied. Save space and energy. Compared with layered fermenters, the moving bed design can reduce the floor space, and because it does not require complex stirring or turning mechanisms, the energy consumption is relatively low. More suitable for large-scale continuous fermentation and suitable for long-term, continuous production processes. The structure is relatively complex, and a reasonable bed movement system needs to be designed, and the operation and maintenance may be more complicated. The equipment cost is high, and the initial construction investment may be high, especially when precise control of bed movement and airflow distribution is required. Moving bed fermenters are suitable for large-scale fermentation, especially in processes with high oxygen demand or long-term continuous fermentation, such as the production of certain enzymes, bulk microbial fermentation, etc.

Layered fermenters, as a widely used fermentation equipment, are generally suitable for production processes that require multiple layers of solid matrix for fermentation. This type of fermentation vessel occupies a large space, and each layer needs to be carefully controlled during operation, so it is more cumbersome.

Rotary barrel fermenters are more suitable for small and medium-sized fermentation production. It has a simple structure and is easy to maintain, but the energy consumption is relatively high.

Moving bed fermenters are favored for their large-scale, continuous production methods and high energy efficiency. However, the equipment investment for this type of fermenter is high and the operation is relatively complicated.

In general, when choosing a fermenter that suits your production scale, you should first consider factors such as space size, microbial species, and fermentation conditions. Only when these conditions are met can you ensure that the fermenter can effectively provide support and guarantee for fermentation production.