Fermentation system and fermentation control method

Abstract

The application relates to the fermentation field and discloses a fermentation system and a fermentation control method, which comprise a fermentation tank, a first feeding assembly connected with the fermentation tank and used for conveying a mixed solution of a carbon source and a basic nitrogen source to the fermentation tank, a plurality of material spraying assemblies distributed along the axial direction and / or the circumferential direction of the fermentation tank and capable of spraying a feeding nitrogen source into the fermentation tank, each material spraying assembly being independently controllable, a second feeding assembly connected with the material spraying assemblies, a plurality of detection elements distributed in different areas in the fermentation tank and used for detecting the dissolved oxygen concentration of the corresponding area, and a control system electrically connected with the material spraying assemblies and the detection elements and configured to control the material spraying assemblies in the corresponding area to spray the feeding nitrogen source based on the dissolved oxygen concentration. The first and second feeding assemblies are cooperatively controlled, the former conveys the mixed solution of the carbon source and the nitrogen source to stably supply the basic nutrition and maintain the overall carbon-nitrogen ratio, and the latter supplies the adjusted nitrogen source to the partitioned material spraying assemblies to compensate for the nitrogen concentration gradient caused by the centralized feeding.

Description

Technical Field

[0001] This application relates to the field of fermentation technology, specifically to fermentation systems and fermentation control methods. Background Technology

[0002] In continuous fermentation, precise nutrient supplementation is crucial for maintaining stable cell growth and maximizing product yield. However, traditional feeding methods struggle to effectively address the spatial gradient of nitrogen concentration caused by uneven mixing within large fermenters. This problem easily leads to asynchronous microbial metabolism and increased local environmental pressure, severely impacting the long-term stability and production efficiency of the fermentation process. Therefore, there is an urgent need to develop a fermentation system capable of resolving or improving the uneven nitrogen concentration distribution within fermenters to ensure the efficient and stable operation of continuous fermentation processes. Summary of the Invention

[0003] This application provides a fermentation system and a fermentation control method to solve or improve the problem of uneven nitrogen concentration distribution in fermenters in related technologies.

[0004] In a first aspect, this application provides a fermentation system, comprising: Fermentation tank; The first feeding assembly is connected to the fermenter and is used to feed a mixture of carbon source and basic nitrogen source into the fermenter. Multiple spraying components are distributed along the axial and / or circumferential direction of the fermenter and can spray a supplementary nitrogen source into the fermenter. Each spraying component can be controlled independently. The second feeding component is connected to the spraying component and is used to supply a supplementary nitrogen source to the spraying component; Multiple detection elements are distributed in different areas within the fermenter and are used to detect the dissolved oxygen concentration in the corresponding areas; The control system is electrically connected to the spray assembly and the detection element and is configured to control the spray assembly to spray a supplementary nitrogen source in a corresponding area based on the dissolved oxygen concentration.

[0005] In one optional embodiment, the control system is configured to obtain the dissolved oxygen concentration change rate and / or spatial offset based on the dissolved oxygen concentration, and when it is determined that the dissolved oxygen concentration change rate is greater than or equal to a preset change rate threshold and / or the spatial offset is greater than or equal to a preset offset threshold, control the spraying assembly in the corresponding area to spray a supplementary nitrogen source.

[0006] In one optional implementation, the control system controls the pulse-jet feeding of nitrogen source to the aerosol assembly in the corresponding area based on the dissolved oxygen concentration. And / or, the control system is configured to obtain the standard deviation of dissolved oxygen concentration based on the dissolved oxygen concentration in at least two regions, and to make the spraying frequency and / or spraying duration of the spraying assembly in the corresponding region positively correlated with the standard deviation.

[0007] In one optional embodiment, the pulse spraying of the spraying assembly lasts for 2 to 30 seconds per pulse, and the spraying flow rate is 0.05 L / h to 0.2 L / h.

[0008] In an optional embodiment, the control system is also electrically connected to the first feeding component. The control system is configured to acquire the carbon-nitrogen molar ratio in the fermenter, and when it is determined that the carbon-nitrogen molar ratio is greater than a preset target carbon-nitrogen ratio, control the first feeding component to increase the flow rate of the mixture, and when it is determined that the carbon-nitrogen molar ratio is less than the preset target carbon-nitrogen ratio, control the first feeding component to decrease the flow rate of the mixture. And / or, the amount of nitrogen source supplied by the first feeding component accounts for 70%-90% of the total nitrogen source required for continuous fermentation in the fermenter, as the basic nitrogen supply for fermentation, and the amount of nitrogen source supplied by the second feeding component accounts for 10%-30% of the total nitrogen source required for continuous fermentation in the fermenter, as local nitrogen source compensation. And / or, the carbon-nitrogen molar ratio in the fermenter is 10:1 to 20:1.

[0009] In one optional embodiment, the second feeding assembly includes a feeding pipe, an air source, and a material source. The feeding pipe is connected to each of the spraying assemblies, the air source is connected to the feeding pipe and is used to supply air to the feeding pipe, and the material source is connected to the feeding pipe and is used to supply a supplementary nitrogen source to the feeding pipe. And / or, the spraying assembly includes a nozzle and a control valve, the nozzle being disposed inside the fermenter, the control valve being connected between the second feeding assembly and the nozzle, and the control valve being electrically connected to the control system; And / or, the spraying assembly is provided at least at one location: below the liquid surface in the fermenter, near the liquid surface; on the side wall of the fermenter; at the corner where the side wall and bottom wall of the fermenter meet; and in the interlayer region between the two layers of agitators. And / or, the fermentation system further includes a stirring paddle, which is rotatably disposed within the fermentation tank.

[0010] In one optional embodiment, the fermentation system is used to prepare single-cell protein; preferably, the fermentation system is used to ferment microbial cells using acetic acid-containing wastewater as a carbon source to prepare single-cell protein. And / or, the specific growth rate of the microbial cells in the fermenter is 0.1 h⁻¹. -1 ~0.2h -1 .

[0011] Secondly, this application provides a fermentation control method, comprising: The dissolved oxygen concentration in different areas of a fermenter is obtained, wherein a mixture of carbon source and basic nitrogen source is continuously circulated into the fermenter; Based on the dissolved oxygen concentration, the spraying assembly in the corresponding area is controlled to spray a supplementary nitrogen source.

[0012] In one optional implementation, based on the dissolved oxygen concentration, controlling the spraying assembly in the corresponding area to spray supplementary nitrogen source includes: obtaining the dissolved oxygen concentration change rate and / or the spatial offset of the dissolved oxygen concentration according to the dissolved oxygen concentration, and controlling the spraying assembly in the corresponding area to spray supplementary nitrogen source when it is determined that the dissolved oxygen concentration change rate is greater than or equal to a preset change rate threshold and / or the spatial offset is greater than or equal to a preset offset threshold. And / or, based on the dissolved oxygen concentration, controlling the spraying of a nitrogen source by the spraying assembly in the corresponding area includes: controlling the spraying assembly in the corresponding area to pulse-jet spray a nitrogen source based on the dissolved oxygen concentration; And / or, the fermentation control method further includes: obtaining the standard deviation of dissolved oxygen concentration based on the dissolved oxygen concentration in at least two regions, and making the spraying frequency and / or spraying duration of the spraying assembly in the corresponding regions positively correlated with the standard deviation.

[0013] In an optional embodiment, the method further includes: obtaining the carbon-nitrogen molar ratio in the fermenter, and increasing the flow rate of the mixture when the carbon-nitrogen molar ratio is determined to be greater than a preset target carbon-nitrogen ratio, and decreasing the flow rate of the mixture when the carbon-nitrogen molar ratio is determined to be less than the preset target carbon-nitrogen ratio; And / or, the amount of nitrogen source supplied by the mixture accounts for 70%-90% of the total nitrogen source required for continuous fermentation in the fermenter, as the basic nitrogen supply for fermentation, and the sum of the nitrogen sources supplied by the spraying components accounts for 10%-30% of the total nitrogen source required for continuous fermentation in the fermenter, as local nitrogen source compensation. And / or, the carbon-nitrogen molar ratio in the fermenter is 10:1 to 20:1; And / or, the fermentation control method is used to prepare single-cell protein, preferably, the fermentation control method is used to ferment microbial cells using acetic acid-containing wastewater as a carbon source to prepare single-cell protein; And / or, the specific growth rate of the microbial cells in the fermenter is 0.1 h⁻¹. -1 ~0.2h -1 .

[0014] The fermentation system provided in this application has multiple independently adjustable spraying components arranged along the axial and circumferential directions of the fermenter as distributed nitrogen feeding points. The detection elements in each area collect the dissolved oxygen concentration at the corresponding location in real time and feed it back to the control system. The control system controls the start and stop of the spraying of ammonia water to feed nitrogen source according to the dissolved oxygen situation in each area. It can accurately and directionally supplement nitrogen source to local areas with low nitrogen content and higher metabolic demand of microorganisms, eliminate the spatial stratification of nitrogen concentration in the tank and the situation of local nitrogen deficiency or nitrogen excess, keep the nitrogen nutrient distribution in the whole tank uniform and uniform, and keep the metabolic state of microorganisms synchronous and stable. It reduces the inhibition of microbial growth by local environmental pressure and continuously ensures the long-term stability of continuous fermentation.

[0015] Furthermore, this application sets up a first feeding component and a second feeding component to work together. The first feeding component uniformly delivers a premixed mixture of carbon source and basic nitrogen source into the tank, achieving a stable and continuous supply of basic nutrients and maintaining the basic carbon-nitrogen ratio of the fermentation system to meet the basic growth needs of the microbial cells. The second feeding component separately supplies ammonia water to the distributed spraying component as a precisely regulated nitrogen source. The overall basic feeding ensures that the total supply of nutrients will not be insufficient, while the distributed, independently controllable spraying component compensates for the uneven nitrogen distribution caused by single-point centralized feeding. The two components work together to solve the problem of nitrogen concentration gradient caused by single-point centralized feeding, and avoid the defects of distributed feeding that cannot stably supply sufficient basic nutrients and cannot maintain a stable carbon-nitrogen ratio in the system. This balances the total nutrient supply and the uniformity of spatial distribution, continuously optimizes the microbial growth environment, and improves the accumulation of target products and the overall fermentation production efficiency.

[0016] The fermentation control method provided in this application has the same technical features as the fermentation system provided in this application, and therefore includes all the advantages of the fermentation system mentioned above. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the fermentation system provided in an embodiment of this application; Figure 2 A control principle diagram of the fermentation system provided in the embodiments of this application; Figure 3 This is a schematic flowchart of the fermentation control method provided in the embodiments of this application.

[0019] Explanation of reference numerals in the attached figures: 1. Fermentation tank; 2. First feeding assembly; 201. Regulating valve; 3. Spraying assembly; 301. Nozzle; 302. Control valve; 4. Second feeding assembly; 401. Conveying pipe; 402. Air source; 403. Material source; 404. Filter assembly; 5. Detection element; 6. Control system; 7. Agitator. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] The following is combined Figures 1 to 3 This describes the fermentation system provided in the embodiments of this application.

[0022] Specifically, the fermentation system includes a fermenter 1, a first feeding component 2, a spraying component 3, a second feeding component 4, a detection element 5, and a control system 6.

[0023] Among them, fermentation tank 1 is set as a tank body to provide a fermentation site.

[0024] The first feeding component 2 is connected to the fermenter 1 and is used to supply a mixture of carbon source and basic nitrogen source to the fermenter 1. Optionally, the carbon source can be acetic acid-containing wastewater, and the basic nitrogen source can be ammonia water. The carbon source and basic nitrogen source are mixed in a preset ratio and then transported to the fermenter 1 through the first feeding component 2.

[0025] There are multiple spraying components 3, which are distributed along the axial and / or circumferential direction of the fermenter 1. For example, the spraying components 3 are configured as multiple groups distributed along the axial direction of the fermenter 1, and multiple spraying components 3 within a group are distributed along the circumferential direction of the fermenter 1. The spraying components 3 are used to spray a supplementary nitrogen source into the fermenter 1, and each spraying component 3 can be controlled independently, that is, each spraying component 3 can be started or stopped independently. The supplementary nitrogen source is ammonia water.

[0026] The second feeding component 4 is connected to the spraying component 3 and is used to supply the spraying component 3 with a nitrogen source.

[0027] Multiple detection elements 5 are distributed in different areas within the fermenter 1 to detect the dissolved oxygen concentration in their respective areas. The detection elements 5 can be configured as dissolved oxygen probes. Optionally, the detection elements 5 can be distributed along the axial direction of the fermenter 1. Specifically, the detection elements 5 are configured as multiple groups distributed along the axial direction of the fermenter 1, with multiple detection elements 5 within each group distributed circumferentially along the fermenter 1. For example, the positions of the detection elements 5 correspond to the positions of the spraying components 3, meaning that the spraying components 3 are respectively located in the areas where the corresponding detection elements 5 are located.

[0028] The control system 6 is electrically connected to the spray assembly 3 and the detection element 5, and is configured to control the spray assembly 3 to spray a supplementary nitrogen source in the corresponding area based on the dissolved oxygen concentration.

[0029] The existing fermenter 1 uses a uniform feeding method to deliver nitrogen source. Uneven mixing within the tank creates a significant spatial gradient of nitrogen concentration, resulting in large differences in nitrogen nutrient supply to microorganisms in different areas. This leads to inconsistent metabolic rhythms of the microbial community and increased local environmental stress. This application deploys multiple independently controllable spraying components 3 along the axial and circumferential directions of fermenter 1 as distributed nitrogen replenishment points. Detection elements 5 in each area collect dissolved oxygen concentration data in real time and feed it back to the control system 6. The control system 6 independently controls the start and stop of ammonia water spraying to replenish nitrogen source based on the dissolved oxygen status of each area. This allows for precise targeted nitrogen replenishment to localized areas with low nitrogen content and higher microbial metabolic demands, eliminating spatial stratification of nitrogen concentration within the tank and preventing localized nitrogen deficiency or excess. This ensures uniform and consistent nitrogen nutrient distribution throughout the tank, synchronized and stable metabolic states of the microorganisms, reduces the inhibitory effect of local environmental stress on microbial growth, and continuously guarantees the stability of long-term continuous fermentation operation.

[0030] In addition, this application sets up a first feeding component 2 and a second feeding component 4 to work together. The first feeding component 2 uniformly delivers a premixed mixture of carbon source and basic nitrogen source into the tank, achieving a stable and continuous supply of basic nutrients and maintaining the basic carbon-nitrogen ratio of the fermentation system to meet the basic growth needs of the microbial cells. The second feeding component 4 separately supplies ammonia water to the distributed spraying component 3 as a precisely regulated nitrogen source. The overall basic feeding ensures that the total supply of nutrients will not be insufficient. The distributed, independently controllable spraying component 3 compensates for the uneven nitrogen distribution caused by single-point centralized feeding. The two components work together to solve the problem of nitrogen concentration gradient caused by single-point centralized feeding, and avoid the defects of distributed feeding that cannot stably supply sufficient basic nutrients and cannot maintain a stable carbon-nitrogen ratio in the system. It takes into account both the total nutrient supply and the uniformity of spatial distribution, continuously optimizes the microbial growth environment, and improves the accumulation of target products and the overall fermentation production efficiency.

[0031] Optionally, multiple detection elements 5 are distributed sequentially along the height direction of the fermenter 1. Correspondingly, multiple sets of spraying components 3 are distributed sequentially along the height direction of the fermenter. Each set of spraying components 3 includes at least one spraying component 3. When there are two or more spraying components 3 in a set, they can be distributed circumferentially along the fermenter 1. Optionally, the number of detection elements 5 is 3 to 10. For example, the number of detection elements 5 is 3, 4, 5, 6, 7, 8, 9, or 10.

[0032] In some embodiments provided by the present invention, the control system 6 is configured to obtain the dissolved oxygen concentration change rate according to the dissolved oxygen concentration, and when it is determined that the dissolved oxygen concentration change rate is greater than or equal to a preset change rate threshold, control the spraying component 3 in the corresponding area to spray the supplementary nitrogen source.

[0033] When the metabolic intensity of microorganisms in a local area of ​​fermenter 1 increases, oxygen is consumed rapidly, directly causing a rapid decrease in dissolved oxygen concentration in that area. Relying solely on instantaneous dissolved oxygen values ​​to judge nitrogen source shortages is susceptible to misjudgment due to interference from instantaneous stirring, fluid disturbances, etc.

[0034] Specifically, the control system 6 can continuously collect the real-time dissolved oxygen concentration output by the corresponding detection element 5 at different time points, record the dissolved oxygen concentration at two adjacent collection times and the time interval between the two times, and calculate the dissolved oxygen concentration change rate by dividing the difference between the two dissolved oxygen concentrations by the collection time interval. The control system 6 continuously collects and calculates according to a fixed sampling cycle, continuously updating the real-time dissolved oxygen change rate of each region, thereby capturing the rate of increase and decrease of local dissolved oxygen as a dynamic basis for judging the nitrogen deficiency of bacterial metabolism.

[0035] In this embodiment, the control system 6 calculates the rate of change of dissolved oxygen concentration in each region in real time, and uses the rate of decrease in concentration as the basis for judging whether the bacteria are deficient in nitrogen nutrition and have a surge in metabolic activity. Compared with a single static dissolved oxygen value, this method is more sensitive and reliable, can filter out invalid signals caused by fluid fluctuations, and can more accurately identify the actual local nitrogen supply shortage. Once the rate of change of dissolved oxygen in a region reaches a set threshold, the corresponding spraying component 3 is immediately driven to spray a supplementary nitrogen source. The independent spraying component 3 in each zone completes the rapid replenishment of local nitrogen nutrition, timely matches the sudden increase in the nutritional consumption demand of the bacteria in that region, avoids metabolic imbalance caused by continuous high-intensity oxygen consumption due to nitrogen deficiency in the local bacteria, and simultaneously eliminates the concentration gradient caused by local nitrogen deficiency and nitrogen surplus in other regions.

[0036] Meanwhile, by predicting and intervening in the regulation based on the rate of change of dissolved oxygen concentration, the feeding response time can be shortened compared with the lagging static numerical regulation. This forms a front-end closed-loop regulation based on dynamic metabolic changes, enabling dynamic tracking and real-time adaptation of the metabolic state of microorganisms in the micro-zone of fermenter 1. This balances the overall nutritional balance of the entire tank with the dynamic metabolic needs of local areas, further weakens the differences in the spatial environment inside the tank, and continuously maintains the stable and synchronous growth of microorganisms in all areas, thus improving the stability of continuous fermentation operation and the efficiency of product synthesis in the long term.

[0037] It should be understood that the determination of whether to inject supplemental nitrogen is required is not limited to the rate of change of dissolved oxygen concentration. For example, in other embodiments provided by the present invention, the control system 6 is configured to obtain the spatial offset of dissolved oxygen concentration based on the dissolved oxygen concentration, and control the spraying assembly 3 in the corresponding area to inject supplemental nitrogen when the spatial offset is determined to be greater than or equal to a preset offset threshold.

[0038] In this embodiment, by introducing the spatial offset of dissolved oxygen concentration as the basis for feed control, the regulation dimensions of the fermentation system can be further enriched. When nitrogen is deficient in certain areas of the tank, the microorganisms consume oxygen more rapidly, and the dissolved oxygen value in these areas will be significantly lower than in other locations, resulting in a large spatial offset. The control system calculates the spatial offset by measuring the deviation between the dissolved oxygen data measured by each detection element, which can intuitively reflect the degree of imbalance in the metabolic state within the tank.

[0039] When the spatial offset exceeds the preset offset threshold, it means that the difference in oxygen consumption of bacteria between regions is too large, which corresponds to the imbalance of nitrogen source distribution. At this time, the corresponding region spraying component is activated to supplement the nitrogen source, which can specifically improve the nitrogen supply in areas with high oxygen consumption, reduce the difference in bacterial metabolic level between regions, and correct the problem of nutrient deficiency in specific regions.

[0040] Meanwhile, the control strategy based on spatial offset can complement the aforementioned dynamic regulation based on the rate of change of dissolved oxygen concentration. It can capture the drastic fluctuations in local metabolic intensity from the time dimension and monitor the balance of the nutritional environment of the whole tank from the spatial dimension, thereby constructing a closed-loop regulation mechanism covering both time and space.

[0041] Understandably, the spatial offset can be selected from either the relative deviation or the standardized deviation.

[0042] Regarding the calculation of relative deviation: calculate the average dissolved oxygen concentration measured by all detection elements 5, and the relative deviation at a single point = (dissolved oxygen concentration measured by the corresponding detection element 5 - average dissolved oxygen concentration) ÷ average dissolved oxygen concentration.

[0043] Regarding the calculation of standardized deviation: Calculate the average value and standard deviation of dissolved oxygen concentration corresponding to all detection elements 5. The standardized deviation of a single point = (dissolved oxygen concentration measured by the corresponding detection element 5 - average dissolved oxygen concentration) ÷ standard deviation.

[0044] In some embodiments provided by the present invention, the control system 6 controls the atomizing assembly 3 in a pulsed manner to replenish the nitrogen source based on the dissolved oxygen concentration. For example, the control system 6 controls the atomizing assembly 3 to periodically spray or stop spraying to form a pulsed spray pattern.

[0045] In this embodiment, the spraying component 3 pauses feeding immediately after each single spray of nitrogen source, allowing the sprayed nitrogen source to fully diffuse and mix in the local area. This prevents excessively high instantaneous nitrogen concentrations caused by prolonged continuous spraying, avoiding excessive nitrogen in certain areas that could inhibit cell metabolism. It also prevents the accumulation of feed and the formation of new concentration differences, and avoids disrupting the carbon-nitrogen metabolic balance of the cells due to a single large-scale nitrogen injection. Furthermore, the independent spraying structure in different zones ensures that each pulse spray specifically replenishes the currently oxygen-deficient nitrogen-laden area. This intermittent diffusion pattern allows the nitrogen source to be evenly integrated into the surrounding fermentation broth, continuously reducing the nitrogen concentration difference between different areas within the tank.

[0046] In some embodiments provided by the present invention, the control system 6 is configured to obtain the standard deviation of dissolved oxygen concentration based on the dissolved oxygen concentration of at least two regions, and to make the spraying frequency and / or spraying duration of the spraying component 3 in the corresponding region positively correlated with the standard deviation.

[0047] Optionally, the control system 6 employs a proportional-integral (PI) control algorithm, using the standard deviation of dissolved oxygen concentration as the controlled variable and the spraying frequency or duration of the spraying component 3 as the manipulated variable. For example, the proportional coefficient of the PPI control algorithm is set to 0.8, and the integral time constant is set to 120 seconds. The control system 6 calculates the deviation between the standard deviation and the set value in real time, responding quickly to the current deviation through the proportional term and eliminating steady-state error through the integral term. When the standard deviation is higher than the set value, the control system 6 increases the spraying frequency of the spraying component 3 from 3 times per minute to 5 times per minute, or extends the duration of a single spray from 2 seconds to 4 seconds. When the standard deviation is lower than the set value, the control system 6 correspondingly reduces the spraying frequency or shortens the spraying duration. This closed-loop control method can accurately maintain the stability of dissolved oxygen in the fermenter 1, controlling the dissolved oxygen concentration within the range of 0.8-2.5 mg / L, effectively improving fermentation efficiency and product quality.

[0048] In this embodiment, by calculating the standard deviation of dissolved oxygen concentration in multiple regions, the degree of unevenness of the metabolic environment in each region of the fermenter 1 can be quantified. The larger the standard deviation value, the more obvious the difference in oxygen consumption of bacteria in different regions of the tank, and the more prominent the problem of nitrogen nutrient distribution imbalance. By establishing a positive correlation between the spraying frequency and single spraying duration of the spraying component 3 and the standard deviation, the feeding intensity can be dynamically matched according to the degree of unevenness of the whole tank.

[0049] Specifically, when there are large differences in dissolved oxygen and significant nitrogen concentration gradients in different zones, the spraying frequency or duration is increased to rapidly smooth out nutrient differences in the regions by increasing local nitrogen supply. When dissolved oxygen levels in different zones tend to be uniform and the standard deviation decreases, the feed output intensity is reduced simultaneously to prevent excessive nitrogen supplementation from causing local nitrogen accumulation. This setup allows for coordinated adjustment of the overall distribution of fermenter 1, avoiding the problem of neglecting overall uniformity when controlling only a local area. It continuously reduces the spatial gradient between nitrogen and dissolved oxygen within the tank, ensuring a synchronized and balanced nutrient supply to the microorganisms throughout the tank, reducing asynchronous metabolic phenomena, stabilizing continuous fermentation operations, and improving the stability of product synthesis.

[0050] Optionally, the duration of a single pulse spray of the abrasive assembly 3 is 2 to 30 seconds, and the duration of a single pulse spray of the abrasive assembly 3 is 2 seconds, 3 seconds, 5 seconds, 8 seconds, 10 seconds, 15 seconds, 20 seconds, 25 seconds or 30 seconds.

[0051] This setup allows for flexible adjustment of the amount of nitrogen replenishment per application to suit different local nitrogen deficiencies in fermenter 1. Short-duration spraying involves only a small amount of ammonia, suitable for conditions with a small dissolved oxygen standard deviation and minimal regional nutrient differences. After the small amount of nitrogen is added, it mixes quickly and easily thanks to the flow of the fermentation broth, preventing sudden increases in local nitrogen concentration that could inhibit cell metabolism. Long-duration spraying can address scenarios with poor stirring, high-density cell metabolism leading to intense oxygen consumption, and large local nitrogen deficits, providing a sufficient amount of nitrogen in a single application to promptly match the nutrient consumption of the cells.

[0052] Optionally, the injection flow rate is 0.05 L / h to 0.2 L / h. For example, the injection flow rate is 0.05 L / h, 0.1 L / h, 0.15 L / h, or 0.2 L / h.

[0053] For example, a low flow rate of 0.05 L / h is suitable for fermentation environments with a uniform overall flow and requiring only trace amounts of nitrogen supplementation. The low-speed spraying of ammonia water can quickly mix with the surrounding fermentation broth, preventing localized instantaneous nitrogen spikes. A high flow rate of 0.2 L / h can address areas in fermenter 1 where there are no stirring dead zones, high bacterial metabolism, or large nitrogen deficits, allowing for faster replenishment of nutrient consumption. The two flow rates of 0.1 L / h and 0.15 L / h form a gentle gradient, allowing for precise matching of flow rate based on the degree of imbalance within the tank, as reflected by the dissolved oxygen standard deviation.

[0054] In some embodiments provided by the present invention, the control system 6 is also electrically connected to the first feeding assembly 2. For example, the first feeding assembly 2 includes a pipe and a regulating valve 201 disposed on the pipe, and the control system 6 is electrically connected to the regulating valve 201. The regulating valve 201 may be a solenoid valve or a pneumatic valve.

[0055] Furthermore, the control system 6 is configured to acquire the carbon-nitrogen molar ratio in the fermenter 1, and when it is determined that the carbon-nitrogen molar ratio is greater than the preset target carbon-nitrogen ratio, control the first feeding component 2 to increase the flow rate of the mixture, and when it is determined that the carbon-nitrogen molar ratio is less than the preset target carbon-nitrogen ratio, control the first feeding component 2 to decrease the flow rate of the mixture.

[0056] It should be understood that the control system 6 can obtain the content of carbon and nitrogen elements by the detection sensors installed in the fermenter 1 and calculate the carbon-nitrogen molar ratio, or it can obtain the carbon-nitrogen molar ratio by offline acquisition and measurement and transmit it to the control system 6.

[0057] In this embodiment, a preset target carbon-nitrogen molar ratio is used as the adjustment benchmark. When the measured carbon-nitrogen molar ratio is too high, it means that the overall carbon in fermenter 1 is relatively excessive and the nitrogen supply is insufficient. The control system 6 drives the regulating valve 201 to increase the flow rate of the mixed liquid and simultaneously supplement the fixed carbon source and basic nitrogen source to quickly correct the overall carbon-nitrogen ratio. When the measured carbon-nitrogen molar ratio is too low, it means that the nitrogen in the system is relatively abundant. The regulating valve 201 is then controlled to reduce the feed flow rate to prevent excessive feeding from further aggravating the carbon-nitrogen imbalance. This regulation provides steady-state control of the overall nutrient ratio of fermenter 1 and forms a layered complement with the local fine-tuning of the nitrogen source by the zoned spraying component 3. It stabilizes the overall carbon-nitrogen nutrient base from the feed source and avoids problems such as limited cell proliferation, large-scale generation of by-products, and reduced synthesis efficiency of target products caused by the long-term deviation of the carbon-nitrogen ratio from the optimal range.

[0058] In some embodiments provided by the present invention, the nitrogen source supplied by the first feeding component 2 accounts for 70%-90% of the total nitrogen source required for continuous fermentation in the fermenter 1, serving as the basic nitrogen supply for fermentation. For example, the nitrogen source supplied by the first feeding component 2 accounts for 70%, 75%, 80%, 85%, or 90% of the total nitrogen source required for continuous fermentation in the fermenter 1. The nitrogen source supplied by the second feeding component 4 accounts for 10%-30% of the total nitrogen source required for continuous fermentation in the fermenter 1, serving as local nitrogen source compensation. For example, the nitrogen source supplied by the second feeding component 4 accounts for 10%, 15%, 20%, 25%, or 30% of the total nitrogen source required for continuous fermentation in the fermenter 1.

[0059] In this embodiment, the total nitrogen source is proportionally divided between the first feeding component 2 and the second feeding component 4. The first feeding component 2 is responsible for the majority of the nitrogen source supply. By synchronously conveying the mixture of carbon source and basic nitrogen source, the overall carbon-nitrogen molar ratio of the entire tank is stably controlled, which can fully meet the total amount of basic nitrogen required for the overall growth and metabolism of the microorganisms. This avoids insufficient or excessive overall nitrogen supply from the source of feed, and ensures the stability of the nutrient base of the fermentation system.

[0060] The second feeding component 4 only undertakes a small proportion of nitrogen supplementation, and works with the distributed spraying component 3 to complete local nitrogen compensation in each area. It will not disrupt the overall preset carbon-nitrogen ratio due to excessive compensation nitrogen volume. It is only used to balance the spatial gradient of nitrogen concentration caused by uneven stirring in the tank, and will not cause a large deviation in the overall carbon-nitrogen ratio after local nitrogen supplementation.

[0061] With this setup, the nitrogen source distribution ratio of the first feeding component 2 and the second feeding component 4 are mutually constrained. A large proportion of basic feeding can balance the global nutrition, while a small proportion of zone feeding can eliminate local environmental differences. This not only solves the problem of uneven spatial nitrogen distribution caused by single centralized feeding, but also avoids the drawback of simple large-scale distributed feeding causing the overall carbon-nitrogen ratio to run out of control, thus meeting the requirements for long-term stable operation of continuous fermentation.

[0062] In some embodiments provided by this invention, the carbon-nitrogen molar ratio in fermenter 1 is 10:1 to 20:1. For example, the carbon-nitrogen molar ratio in fermenter 1 is 10:1, 15:1, 18:1, or 20:1. This setting, with a carbon-nitrogen molar ratio range of 10:1 to 20:1, can match the optimal metabolic window for continuous fermentation of industrial microorganisms, avoiding the accumulation of byproducts due to excess carbon or the excessive cell growth caused by excess nitrogen, thus ensuring the efficiency and quality of product synthesis.

[0063] In some embodiments provided by the present invention, the second feeding component 4 includes a feeding pipe 401, an air source 402, and a material source 403.

[0064] The feed pipe 401 is connected to each of the spraying components 3, and can be connected to each spraying component 3 via pipelines. An air source 402 is connected to the feed pipe 401 and is used to supply air to the feed pipe 401. The air source 402 can be the ventilation system of the fermenter 1, which includes a compressor and a filter assembly 404 located at the compressor outlet. A feed source 403 is connected to the feed pipe 401 and is used to supply feed nitrogen to the feed pipe 401. The feed source 403 can be a pipeline or a storage tank.

[0065] In this embodiment, the second feeding component 4 adopts an air-feeding structure in which the air source 402 and the material source 403 are connected to the conveying pipe 401 and then conveyed to each spraying component 3. The original ventilation system of the fermentation tank 1 can be directly reused as the air source 402, without the need to add an independent air supply compressor and filtration equipment. The ventilation system's built-in compressor provides the conveying power, and the outlet filter component 404 sterilizes and purifies the compressed air, avoiding the risk of contamination caused by the compressed air carrying bacteria into the fermentation tank 1. The existing equipment is fully utilized to simplify the hardware configuration of the entire feeding device, reducing equipment investment and on-site installation space occupation.

[0066] The material source 403 stores ammonia water separately and feeds nitrogen source and is connected to the conveying pipe 401. Compressed air is used as carrier gas to carry the nitrogen source liquid along the conveying pipe 401 to each independent spraying component 3. Relying on air pressure drive, it can ensure stable flow rate when conveying over long distances and through multiple branch pipelines, and prevent the problem of insufficient material output and weak spraying of the remote spraying component 3 caused by pipeline pressure drop.

[0067] In some embodiments provided by the present invention, the spraying assembly 3 includes a nozzle 301 and a control valve 302. The nozzle 301 is disposed inside the fermentation tank 1, and the control valve 302 is connected between the second feeding assembly 4 and the nozzle 301. The control valve 302 is electrically connected to the control system 6. The control valve 302 can be configured as a solenoid valve or a pneumatic valve.

[0068] With this configuration, the control valve 302 is electrically connected to the control system 6, allowing it to quickly open and close based on real-time signals such as the dissolved oxygen standard deviation, matching the duration and frequency requirements of the pulse injection to ensure timely replenishment response and accurate dosage. The nozzle 301 is built into the tank, directly injecting the nitrogen source into the target area, avoiding pipeline residue and mixing delays, and improving local correction efficiency.

[0069] In some embodiments provided by the present invention, at least one location is provided with a spraying assembly 3: below the liquid surface in the fermenter 1, near the liquid surface, on the side wall of the fermenter 1, at the corner where the side wall and bottom wall of the fermenter 1 meet, and in the interlayer area between the two layers of stirring paddles 7.

[0070] Spraying components 3 are installed in weak mixing areas inside fermenter 1, such as near the liquid surface, tank side wall, tank bottom corner, and double-layer stirring paddle 7 jacket, to provide targeted nitrogen supplementation to stirring dead corners where nitrogen concentration gradients are easily generated by conventional feeding methods.

[0071] For example, the fluid flow rate is weak in the area below the liquid surface, and the surface bacteria are prone to insufficient nitrogen supply. The corresponding nozzle 301 can quickly replenish the nitrogen source to balance the surface nutrition. The fluid flow is slow on the side wall of the tank, and the material exchange efficiency is low. The spraying arrangement on the side wall can eliminate the long-term nitrogen deficiency problem on the side wall. The corner of the bottom of the tank is a blind zone of stirring, and the fermentation liquid is seriously stagnant, which can easily form a local nitrogen-deficient area. The nozzle 301 is set here to specifically improve the bottom nutrient environment. The fluid disturbance in the interlayer between the two layers of stirring paddles 7 is weak, and the material exchange between the upper and lower layers is insufficient. It is easy for the metabolic environment of the interlayer area to become disconnected from the main body of the tank. The matching spraying component 3 can smooth out the nitrogen concentration difference between the interlayer and the main flow area.

[0072] Independent and controllable spraying components 3 are installed at the above-mentioned multiple points prone to imbalance, covering various mixing defects in the fermenter 1. This can eliminate nutrient stratification. Combined with zoned dissolved oxygen detection and pulse injection control, it avoids the drawback of traditional centralized feeding, which can only optimize the central area and dead corners of the tank and cause continuous nutrient imbalance. This makes the nitrogen nutrient distribution in the tank from top to bottom and from the center to the tank wall more uniform.

[0073] In some embodiments of the present invention, the fermentation system further includes a stirring paddle 7, which is rotatably disposed within the fermentation tank 1. The stirring paddle 7 can be driven to rotate by a motor to stir the fermentation liquid within the fermentation tank 1.

[0074] In this embodiment, the stirring paddle 7 agitates the fermentation liquid inside the tank, which can drive the fluid circulation inside the tank. On the one hand, it can accelerate the rapid diffusion and dilution of the supplementary nitrogen source sprayed by the spraying component 3 in the fermentation liquid, and avoid the ammonia water sprayed by the pulse jet from accumulating around the nozzle 301 for a long time to form a local high nitrogen area. With the multi-point arrangement of the spraying component 3, the nitrogen concentration difference in various parts of the tank is further reduced. On the other hand, the stirring effect improves the dissolved oxygen transfer efficiency of the whole tank, ensuring that the dissolved oxygen value collected by each detection element 5 can truly reflect the actual metabolic level of the bacteria in the corresponding area, so that the control system 6 can make more accurate and reliable judgments on the regional nitrogen supplementation regulation based on dissolved oxygen, dissolved oxygen change rate, and standard deviation.

[0075] In some embodiments provided by this invention, the fermentation system is used to prepare single-cell proteins. For example, the fermentation system is used to ferment microbial cells using acetic acid-containing wastewater as a carbon source to prepare single-cell proteins. Of course, the products of this invention are not limited to single-cell proteins; any scheme that utilizes the fermentation system to obtain the target product through microbial transformation is within the scope of protection of this invention.

[0076] Acetic acid-containing wastewater is inexpensive and can be recycled, but the fermentation process using acetic acid as a carbon source consumes a large amount of nitrogen due to microbial metabolism. Uneven mixing in large fermenters can easily lead to local nitrogen shortages, which inhibits microbial proliferation and reduces the yield of single-cell protein. This application relies on the first feeding component 2 to supply a carbon-nitrogen mixed base material to stably maintain a suitable carbon-nitrogen molar ratio, matching the basic nutrients required for microbial synthesis of single-cell protein at the overall level. Then, relying on the independently controllable spraying components 3 distributed in the mass transfer weak areas such as near the liquid surface, tank wall, bottom corner, and the jacket of the agitator 7, local nitrogen compensation is achieved by adding a small amount of ammonia water, making up for the nitrogen source gap in the stirring dead zone, eliminating the spatial gradient of nitrogen concentration in the tank, and ensuring the synchronous growth of microorganisms throughout the tank. This not only achieves low-carbon production from wastewater resources but also improves the stability of continuous fermentation operation and the efficiency of single-cell protein production.

[0077] In some embodiments provided by the present invention, the specific growth rate of microbial cells in fermenter 1 is 0.1 h⁻¹. -1 ~0.2h -1 .

[0078] In this embodiment, the specific growth rate range is an optimized process window for the fermentation of acetic acid-containing wastewater to prepare single-cell protein, which can balance cell synthesis efficiency and metabolic stability. If the specific growth rate is too low, for example, less than 0.1 h... -1 This can lead to insufficient wastewater treatment throughput and decreased protein yield. If the growth rate is too high, for example, greater than 0.2 hours... -1 Rapid consumption of acetic acid can easily lead to local carbon source depletion or a sudden drop in dissolved oxygen, inducing byproduct accumulation and cell autolysis, which in turn reduces protein quality and yield. This application employs a dual-layer feeding and multi-point pulsed nitrogen supplementation strategy to match the dynamic carbon and nitrogen requirements at this growth rate. This avoids growth restriction caused by nitrogen source lag and prevents ammonia inhibition caused by excessive nitrogen supplementation, allowing the cells to maintain a robust physiological state while efficiently converting acetic acid, ensuring the stability and economy of continuous single-cell protein production.

[0079] refer to Figures 1 to 3 This invention also provides a fermentation control method. It is understood that the fermentation control method can be implemented based on the aforementioned fermentation system. The implementing entity of the fermentation control method can be the control system 6 or an operator; this article describes the implementation entity as the control system 6.

[0080] Specifically, the fermentation control method includes steps S100 and S210.

[0081] Step S100: Obtain the dissolved oxygen concentration in different areas of fermenter 1, wherein a mixture of carbon source and basic nitrogen source is continuously circulated into fermenter 1.

[0082] Specifically, the dissolved oxygen concentration can be detected by the detection element 5. Specifically, the detection element 5 is configured as multiple groups distributed along the axial direction of the fermenter 1, and multiple detection elements 5 within a group are distributed along the circumference of the fermenter 1. The fermenter 1 is connected to the first feeding assembly 2, which is used to supply a mixture of carbon source and basic nitrogen source to the fermenter 1.

[0083] Step S210: Based on the dissolved oxygen concentration, control the spraying component 3 in the corresponding area to spray the replenishing nitrogen source.

[0084] Specifically, the control system 6 is electrically connected to the spraying assembly 3 and the detection element 5, and can control the spraying assembly 3 in the corresponding area to spray the supplementary nitrogen source based on the dissolved oxygen concentration. The spraying assembly 3 is configured as multiple groups distributed along the axial direction of the fermenter 1, and multiple spraying assemblies 3 in each group are distributed along the circumference of the fermenter 1.

[0085] The fermentation control method of this application first collects dissolved oxygen concentration in different areas by using axially and circumferentially arranged detection elements 5 to identify local nitrogen-deficient areas. Then, the control system 6 controls the corresponding spraying component 3 to spray the supplementary nitrogen source in a targeted manner to achieve zoned and directional nitrogen supplementation. This eliminates the spatial stratification of nitrogen concentration in the tank from the control process, balances the nutrient supply to the microorganisms in all areas, and ensures stable operation of continuous fermentation.

[0086] This control method achieves nutrient regulation in two layers. First, a mixture of carbon and basic nitrogen sources is continuously supplied through the first feeding component 2 to ensure stable global basic nutrient replenishment and maintain the overall carbon-nitrogen molar ratio within the tank, meeting the total nutrient consumption for cell growth. Then, based on dissolved oxygen detection results in each zone, the distributed spraying component 3 is independently controlled to perform localized nitrogen compensation. This process achieves coordinated regulation of overall basic feeding and zoned balanced nitrogen replenishment. Compared to traditional single-layer overall feeding control logic, this method addresses both insufficient overall nutrient supply and carbon-nitrogen imbalance through continuous mixing, and compensates for localized nutrient imbalances caused by concentrated feeding by relying on zoned dissolved oxygen feedback to match zoned spraying steps. This single control process simultaneously considers the stability of overall nutrient supply and the uniformity of nutrient spatial distribution within the tank, thereby continuously optimizing the cell growth environment and improving single-cell protein production efficiency.

[0087] In some embodiments provided by the present invention, the spraying of a supplementary nitrogen source by the spraying component 3 in the corresponding area is controlled based on the dissolved oxygen concentration, including: obtaining the dissolved oxygen concentration change rate and / or the spatial offset of the dissolved oxygen concentration according to the dissolved oxygen concentration, and controlling the spraying component 3 in the corresponding area to spray a supplementary nitrogen source when it is determined that the dissolved oxygen concentration change rate is greater than or equal to a preset change rate threshold and / or the spatial offset is greater than or equal to a preset offset threshold.

[0088] Specifically, the control system 6 can continuously collect the real-time dissolved oxygen concentration output by the corresponding detection element 5 at different time points, record the dissolved oxygen concentration at two adjacent collection times and the time interval between the two times, and calculate the dissolved oxygen concentration change rate by dividing the difference between the two dissolved oxygen concentrations by the collection time interval. The control system 6 continuously collects and calculates according to a fixed sampling cycle, continuously updating the real-time dissolved oxygen change rate of each region, thereby capturing the rate of increase and decrease of local dissolved oxygen as a dynamic basis for judging the nitrogen deficiency of bacterial metabolism.

[0089] Simultaneously, the control system 6 can obtain the spatial offset of the dissolved oxygen concentration based on the dissolved oxygen concentration, and when the spatial offset is determined to be greater than or equal to a preset offset threshold, control the spraying assembly 3 in the corresponding area to spray the supplementary nitrogen source. The spatial offset can be selected from either relative deviation or standardized deviation.

[0090] In this embodiment, the control system 6 calculates the rate of change of dissolved oxygen concentration in each region in real time, and uses the rate of decrease in concentration as the basis for judging whether the bacteria are deficient in nitrogen nutrition and have a surge in metabolic activity. Compared with a single static dissolved oxygen value, this method is more sensitive and reliable, can filter out invalid signals caused by fluid fluctuations, and can more accurately identify the actual local nitrogen supply shortage. Once the rate of change of dissolved oxygen in a region reaches a set threshold, the corresponding spraying component 3 is immediately driven to spray a supplementary nitrogen source. The independent spraying component 3 in each zone completes the rapid replenishment of local nitrogen nutrition, timely matches the sudden increase in the nutritional consumption demand of the bacteria in that region, avoids metabolic imbalance caused by continuous high-intensity oxygen consumption due to nitrogen deficiency in the local bacteria, and simultaneously eliminates the concentration gradient caused by local nitrogen deficiency and nitrogen surplus in other regions.

[0091] Meanwhile, by predicting and intervening in the regulation based on the rate of change of dissolved oxygen concentration, the feeding response time can be shortened compared with the lagging static numerical regulation. This forms a front-end closed-loop regulation based on dynamic metabolic changes, enabling dynamic tracking and real-time adaptation of the metabolic state of microorganisms in the micro-zone of fermenter 1. This balances the overall nutritional balance of the entire tank with the dynamic metabolic needs of local areas, further weakens the differences in the spatial environment inside the tank, and continuously maintains the stable and synchronous growth of microorganisms in all areas, thus improving the stability of continuous fermentation operation and the efficiency of product synthesis in the long term.

[0092] By introducing the spatial offset of dissolved oxygen concentration as a basis for feed control, the regulation dimensions of the fermentation system can be further enriched. When nitrogen is deficient in certain areas of the tank, the microorganisms consume oxygen more rapidly, and the dissolved oxygen value in these areas will be significantly lower than in other locations, resulting in a large spatial offset. The control system calculates the spatial offset by measuring the dissolved oxygen data between various detection elements, which can intuitively reflect the degree of imbalance in the metabolic state within the tank.

[0093] When the spatial offset exceeds the preset offset threshold, it means that the difference in oxygen consumption of bacteria between regions is too large, which corresponds to the imbalance of nitrogen source distribution. At this time, the corresponding region spraying component is activated to supplement the nitrogen source, which can specifically improve the nitrogen supply in areas with high oxygen consumption, reduce the difference in bacterial metabolic level between regions, and correct the problem of nutrient deficiency in specific regions.

[0094] Meanwhile, the control strategy based on spatial offset can complement the aforementioned dynamic regulation based on the rate of change of dissolved oxygen concentration. It can capture the drastic fluctuations in local metabolic intensity from the time dimension and monitor the balance of the nutritional environment of the whole tank from the spatial dimension, thereby constructing a closed-loop regulation mechanism covering both time and space.

[0095] In some embodiments provided by the present invention, the spraying of nitrogen source by the spraying assembly 3 in a corresponding area is controlled based on the dissolved oxygen concentration, including: controlling the spraying assembly 3 in a pulsed manner to spray nitrogen source based on the dissolved oxygen concentration. For example, the control system 6 controls the control valve 302 of the spraying assembly 3 to periodically open and close to form a pulsed spray pattern.

[0096] In this embodiment, the spraying component 3 pauses feeding immediately after each single spray of nitrogen source, allowing the sprayed nitrogen source to fully diffuse and mix in the local area. This prevents excessively high instantaneous nitrogen concentrations caused by prolonged continuous spraying, avoiding excessive nitrogen in certain areas that could inhibit cell metabolism. It also prevents the accumulation of feed and the formation of new concentration differences, and avoids disrupting the carbon-nitrogen metabolic balance of the cells due to a single large-scale nitrogen injection. Furthermore, the independent spraying structure in different zones ensures that each pulse spray specifically replenishes the currently oxygen-deficient nitrogen-laden area. This intermittent diffusion pattern allows the nitrogen source to be evenly integrated into the surrounding fermentation broth, continuously reducing the nitrogen concentration difference between different areas within the tank.

[0097] In some embodiments provided by the present invention, the fermentation control method further includes step S220.

[0098] Step S220: Obtain the standard deviation of dissolved oxygen concentration based on the dissolved oxygen concentration of at least two regions, and make the spraying frequency and / or spraying duration of the spraying component 3 in the corresponding region positively correlated with the standard deviation.

[0099] Specifically, control system 6 employs a proportional-integral (PI) control algorithm, using the standard deviation of dissolved oxygen concentration as the controlled variable and the spraying frequency or duration of the spraying component 3 as the manipulated variable. For example, the proportional coefficient of the PPI control algorithm is set to 0.8, and the integral time constant is set to 120 seconds. Control system 6 calculates the deviation between the standard deviation and the set value in real time, responding quickly to the current deviation through the proportional term and eliminating steady-state error through the integral term. When the standard deviation is higher than the set value, control system 6 increases the spraying frequency of the spraying component 3 from 3 times per minute to 5 times per minute, or extends the duration of a single spray from 2 seconds to 4 seconds. When the standard deviation is lower than the set value, control system 6 correspondingly reduces the spraying frequency or shortens the spraying duration. This closed-loop control method can accurately maintain the stability of dissolved oxygen in fermenter 1, controlling the dissolved oxygen concentration within the range of 0.8-2.5 mg / L, effectively improving fermentation efficiency and product quality.

[0100] In this embodiment, by calculating the standard deviation of dissolved oxygen concentration in multiple regions, the degree of unevenness of the metabolic environment in each region of the fermenter 1 can be quantified. The larger the standard deviation value, the more obvious the difference in oxygen consumption of bacteria in different regions of the tank, and the more prominent the problem of nitrogen nutrient distribution imbalance. By establishing a positive correlation between the spraying frequency and single spraying duration of the spraying component 3 and the standard deviation, the feeding intensity can be dynamically matched according to the degree of unevenness of the whole tank.

[0101] Specifically, when there are large differences in dissolved oxygen and significant nitrogen concentration gradients in different zones, the spraying frequency or duration is increased to rapidly smooth out nutrient differences in the regions by increasing local nitrogen supply. When dissolved oxygen levels in different zones tend to be uniform and the standard deviation decreases, the feed output intensity is reduced simultaneously to prevent excessive nitrogen supplementation from causing local nitrogen accumulation. This setup allows for coordinated adjustment of the overall distribution of fermenter 1, avoiding the problem of neglecting overall uniformity when controlling only a local area. It continuously reduces the spatial gradient between nitrogen and dissolved oxygen within the tank, ensuring a synchronized and balanced nutrient supply to the microorganisms throughout the tank, reducing asynchronous metabolic phenomena, stabilizing continuous fermentation operations, and improving the stability of product synthesis.

[0102] In some embodiments provided by the present invention, the fermentation control method further includes step S300.

[0103] Step S300: Obtain the carbon-nitrogen molar ratio in fermenter 1, and increase the flow rate of the mixture when the carbon-nitrogen molar ratio is greater than the preset target carbon-nitrogen ratio, and decrease the flow rate of the mixture when the carbon-nitrogen molar ratio is less than the preset target carbon-nitrogen ratio.

[0104] Specifically, the control system 6 is configured to acquire the carbon-nitrogen molar ratio in the fermenter 1, and when the carbon-nitrogen molar ratio is determined to be greater than the preset target carbon-nitrogen ratio, control the first feeding component 2 to increase the flow rate of the mixture, and when the carbon-nitrogen molar ratio is determined to be less than the preset target carbon-nitrogen ratio, control the first feeding component 2 to decrease the flow rate of the mixture.

[0105] In this embodiment, a preset target carbon-nitrogen molar ratio is used as the adjustment benchmark. When the measured carbon-nitrogen molar ratio is too high, it means that the overall carbon in fermenter 1 is relatively excessive and the nitrogen supply is insufficient. The control system 6 drives the regulating valve 201 to increase the flow rate of the mixed liquid and simultaneously supplement the fixed carbon source and basic nitrogen source to quickly correct the overall carbon-nitrogen ratio. When the measured carbon-nitrogen molar ratio is too low, it means that the nitrogen in the system is relatively abundant. The regulating valve 201 is then controlled to reduce the feed flow rate to prevent excessive feeding from further aggravating the carbon-nitrogen imbalance. This regulation provides steady-state control of the overall nutrient ratio of fermenter 1 and forms a layered complement with the local fine-tuning of the nitrogen source by the zoned spraying component 3. It stabilizes the overall carbon-nitrogen nutrient base from the feed source and avoids problems such as limited cell proliferation, large-scale generation of by-products, and reduced synthesis efficiency of target products caused by the long-term deviation of the carbon-nitrogen ratio from the optimal range.

[0106] In some embodiments provided by the present invention, the amount of nitrogen source supplied by the mixed liquid accounts for 70%-90% of the total nitrogen source required for continuous fermentation in fermenter 1, as the basic nitrogen supply for fermentation, and the sum of the nitrogen source supplied by the spraying component 3 accounts for 10%-30% of the total nitrogen source required for continuous fermentation in fermenter 1, as local nitrogen source compensation.

[0107] In this embodiment, the total nitrogen source is proportionally divided between the first feeding component 2 and the second feeding component 4. The first feeding component 2 is responsible for the majority of the nitrogen source supply. By synchronously conveying the mixture of carbon source and basic nitrogen source, the overall carbon-nitrogen molar ratio of the entire tank is stably controlled, which can fully meet the total amount of basic nitrogen required for the overall growth and metabolism of the microorganisms. This avoids insufficient or excessive overall nitrogen supply from the source of feed, and ensures the stability of the nutrient base of the fermentation system.

[0108] The second feeding component 4 only undertakes a small proportion of nitrogen supplementation, and works with the distributed spraying component 3 to complete local nitrogen compensation in each area. It will not disrupt the overall preset carbon-nitrogen ratio due to excessive compensation nitrogen volume. It is only used to balance the spatial gradient of nitrogen concentration caused by uneven stirring in the tank, and will not cause a large deviation in the overall carbon-nitrogen ratio after local nitrogen supplementation.

[0109] With this setup, the nitrogen source distribution ratio of the first feeding component 2 and the second feeding component 4 are mutually constrained. A large proportion of basic feeding can balance the global nutrition, while a small proportion of zone feeding can eliminate local environmental differences. This not only solves the problem of uneven spatial nitrogen distribution caused by single centralized feeding, but also avoids the drawback of simple large-scale distributed feeding causing the overall carbon-nitrogen ratio to run out of control, thus meeting the requirements for long-term stable operation of continuous fermentation.

[0110] In some embodiments provided by this invention, the carbon-nitrogen molar ratio in fermenter 1 is 10:1 to 20:1. This setting, with a carbon-nitrogen molar ratio range of 10:1 to 20:1, can match the optimal metabolic window for continuous fermentation of industrial microorganisms, avoiding the accumulation of byproducts due to excess carbon or the excessive cell growth caused by excess nitrogen, thus ensuring the efficiency and quality of product synthesis.

[0111] In some embodiments provided by this invention, the fermentation control method is used to prepare single-cell proteins. For example, the fermentation control method is used to ferment microbial cells using acetic acid-containing wastewater as a carbon source to prepare single-cell proteins. Of course, the products of this invention are not limited to single-cell proteins; any scheme that utilizes the described fermentation control method to obtain the target product through microbial transformation is within the scope of protection of this invention.

[0112] Acetic acid-containing wastewater is inexpensive and can be recycled, but the fermentation process using acetic acid as a carbon source consumes a large amount of nitrogen due to microbial metabolism. Uneven mixing in large fermenters can easily lead to local nitrogen shortages, which inhibits microbial proliferation and reduces the yield of single-cell protein. This application relies on the first feeding component 2 to supply a carbon-nitrogen mixed base material to stably maintain a suitable carbon-nitrogen molar ratio, matching the basic nutrients required for microbial synthesis of single-cell protein at the overall level. Then, relying on the independently controllable spraying components 3 distributed in the mass transfer weak areas such as near the liquid surface, tank wall, bottom corner, and the jacket of the agitator 7, local nitrogen compensation is achieved by adding a small amount of ammonia water, making up for the nitrogen source gap in the stirring dead zone, eliminating the spatial gradient of nitrogen concentration in the tank, and ensuring the synchronous growth of microorganisms throughout the tank. This not only achieves low-carbon production from wastewater resources but also improves the stability of continuous fermentation operation and the efficiency of single-cell protein production.

[0113] In some embodiments provided by the present invention, the specific growth rate of microbial cells in fermenter 1 is 0.1 h⁻¹. -1 ~0.2h -1 In this embodiment, the specific growth rate range is an optimized process window for the fermentation of acetic acid-containing wastewater to prepare single-cell protein, which can balance cell synthesis efficiency and metabolic stability. If the specific growth rate is too low, for example, less than 0.1 h... -1 This can lead to insufficient wastewater treatment throughput and decreased protein yield. If the growth rate is too high, for example, greater than 0.2 hours... -1 Rapid consumption of acetic acid can easily lead to local carbon source depletion or a sudden drop in dissolved oxygen, inducing byproduct accumulation and cell autolysis, which in turn reduces protein quality and yield. This application employs a dual-layer feeding and multi-point pulsed nitrogen supplementation strategy to match the dynamic carbon and nitrogen requirements at this growth rate. This avoids growth restriction caused by nitrogen source lag and prevents ammonia inhibition caused by excessive nitrogen supplementation, allowing the cells to maintain a robust physiological state while efficiently converting acetic acid, ensuring the stability and economy of continuous single-cell protein production.

[0114] This application also provides embodiments one, two, three and four based on the inventive concept, as well as comparative example one reflecting the prior art.

[0115] Example 1 A fermentation system includes a fermenter 1, a dissolved oxygen probe, a nozzle 301, a first feeding assembly 2, a second feeding assembly 4, and a control system 6.

[0116] Fermentation tank 1 is a 500L cylindrical reaction vessel made of 316L stainless steel, with a polished inner wall to reduce microbial adhesion. The top of fermentation tank 1 has a feed inlet, an exhaust outlet, and various sensor interfaces, while the bottom has a discharge outlet and a sampling port. The side walls of the tank have a jacketed structure, and circulating cooling water maintains the fermentation temperature within the range of 30-32℃.

[0117] To achieve high-precision dissolved oxygen monitoring, an array of eight dissolved oxygen probes is distributed within fermenter 1. The probes are deployed at different heights within the fermenter, for example, depths of 0.2m, 0.4m, 0.6m, 0.8m, 1.0m, 1.2m, 1.4m, and 1.6m. Each dissolved oxygen probe can monitor the dissolved oxygen concentration at its corresponding location in real time, with a monitoring range of 0-20 mg / L and an accuracy of ±0.1 mg / L.

[0118] The outlet of the first feeding component 2 is located at the first position of fermenter 1, which is situated in the lower part of fermenter 1, 0.3m from the bottom. The pipeline uses 316L stainless steel pipe with an inner diameter of 25mm. A regulating valve 201 is installed on the pipeline; this valve is electrically operated, with an opening range of 0-100% and a response time of less than 5 seconds. The first feeding component 2 is used to transport a proportionally mixed carbon and nitrogen source, where the mass ratio of ammonia water to acetic acid wastewater is 1:4, and the feeding rate is 300mL / min. The feeding amount of the first feeding component 2 accounts for 85% of the total nitrogen source supplementation, mainly used to maintain the macroscopic material balance during the fermentation process, ensuring that the macroscopic carbon-nitrogen molar ratio is maintained at 18:1.

[0119] Six nozzles 301 are evenly distributed in different areas within the fermenter 1. Each nozzle 301 has a diameter of 1.2 mm and a designed flow rate of 0.1 L / h. Each nozzle 301 corresponds to a control valve 302, which are fast-response solenoid valves with an opening and closing time of less than 0.1 seconds. A second feeding assembly 4 is connected to each nozzle 301. The feeding amount of the second feeding assembly 4 accounts for 15% of the total nitrogen source supplementation and is mainly used for precise local nitrogen source concentration control.

[0120] The control system 6 employs an industrial control computer, which is electrically connected to the dissolved oxygen probe, the regulating valve 201, and the control valves 302 corresponding to each nozzle 301 on the second feeding assembly 4. The control system 6 acquires signals from each dissolved oxygen probe in real time at a frequency of 10Hz via an industrial Ethernet data collector, and the data is transmitted to the industrial control computer for processing via Ethernet.

[0121] The data processing module of control system 6 analyzes the collected dissolved oxygen time series data and calculates the standard deviation of dissolved oxygen concentration values ​​at at least two different spatial locations, as well as the rate of change of dissolved oxygen at each spatial location. When a sudden decrease in dissolved oxygen is detected at a specific time point (i.e., the rate of change of dissolved oxygen exceeds a preset rate of change threshold), or the spatial offset of dissolved oxygen concentration is greater than or equal to a preset offset threshold, control system 6 immediately triggers the nozzle 301 in the corresponding area to perform pulse feeding. The duration of a single pulse feeding is 15 seconds, and the ammonia feeding rate of nozzle 301 is adjusted to 2 mL / min using a PID control algorithm, with a pulse frequency of 3 times / min.

[0122] The control system 6 simultaneously controls the opening of the regulating valve 201 according to the preset macroscopic carbon-nitrogen molar ratio, and controls the flow rate of the first feeding component 2 by adjusting the opening of the valve 201 in real time, ensuring that the carbon-nitrogen molar ratio is maintained within the range of 10:1 to 20:1. The built-in feedback control algorithm of the control system 6 can dynamically adjust the cooperative working mode of the two feeding channels according to the changes in the cell growth state during fermentation, so that the specific growth rate of the cells is maintained at 0.10-0.20 h⁻¹. - Within the range of ¹.

[0123] Optionally, the pulse replenishment parameters of nozzle 301 can be adjusted. The duration of a single pulse can be set to any value within the range of 2-30 seconds, and the design flow rate of each nozzle 301 can be adjusted to the range of 0.05-0.2L / h to meet the needs of fermenters 1 of different sizes and different strains.

[0124] Optionally, the feeding amount of the first feeding component 2 can account for 70%-90% of the total nitrogen source supplementation, and the feeding amount of the second feeding component 4 can account for 10%-30% of the total nitrogen source supplementation. By adjusting the feeding ratio of the two channels, precise control of the nitrogen source demand at different fermentation stages can be achieved.

[0125] This fermentation system is particularly suitable for continuous fermentation processes producing single-cell protein using acetic acid-containing wastewater as a carbon source. Through dual-channel synergistic feeding and real-time monitoring and adjustment, the system can effectively reduce the uneven distribution of nitrogen source within fermenter 1, improve microbial growth efficiency and product quality, and simultaneously achieve precise control of the fermentation process. Using the method of this invention, the yield of single-cell protein reaches 1.5 g / L / h, and the substrate conversion rate reaches 65%.

[0126] Example 2 A fermentation system includes a fermenter 1 as the main reaction vessel, with a volume of 500L. The fermenter 1 is equipped with an agitator 7 and a ventilation system to maintain the uniformity of the fermentation environment and oxygen supply. Eight dissolved oxygen probes are installed inside the fermenter 1, positioned at different spatial locations within the fermenter 1 and vertically distributed along the central axis of the fermenter 1 at different depths, for example, 0.2m, 0.4m, 0.6m, 0.8m, 1.0m, 1.2m, 1.4m, and 1.6m. This multi-point distribution of dissolved oxygen probes enables real-time monitoring of dissolved oxygen concentration changes in different areas within the fermenter 1, providing the system with comprehensive oxygen distribution information and ensuring timely identification of localized oxygen-deficient areas and triggering corresponding feed replenishment responses.

[0127] The first feeding assembly 2 constitutes the main feeding channel of the system, with its outlet located at the first position of fermenter 1. It is used to transport a proportionally mixed carbon and nitrogen source. This pipeline is designed with a constant flow rate of 300 mL / min, transporting a mixture of ammonia water and acetic acid wastewater, with a mass ratio of ammonia water to acetic acid wastewater of 1:4. The first feeding assembly 2 undertakes 85% of the system's feeding task, providing basic nutrients for the fermentation process and maintaining a nutrient balance of 18:1 carbon-to-nitrogen ratio within fermenter 1.

[0128] There are six nozzles 301, asymmetrically distributed in areas within fermenter 1 where mixing is relatively weak. These nozzles 301 have a diameter of 1.2 mm and are specifically designed for precise localized feeding. The asymmetrical distribution design fully considers the hydrodynamic characteristics within fermenter 1, focusing the nozzles 301 on areas with poor mixing, such as dead zones, near the tank walls, and below the liquid surface. Through integration with the ventilation system, the nozzles 301 can utilize the airflow to enhance the diffusion effect of the feeding, ensuring that the locally supplied nitrogen source can be quickly dispersed to the surrounding area. The second feeding assembly 4 is connected to the nozzles 301. The second feeding assembly 4 undertakes 15% of the system's feeding task, mainly responsible for pulsed precise feeding based on the intensity of dissolved oxygen fluctuations.

[0129] The control system 6, as the core control unit of the system, employs an industrial control computer and is electrically connected to the dissolved oxygen probe, the regulating valve 201 on the first feeding assembly 2, and the control valves 302 corresponding to each nozzle 301 on the second feeding assembly 4. The control system 6 acquires signals from each dissolved oxygen probe in real time at a frequency of 10Hz via an industrial Ethernet data acquisition device, while simultaneously monitoring environmental parameters such as pH value and temperature. After data acquisition, it is transmitted to the control system 6 via Ethernet for real-time processing and analysis.

[0130] Control system 6 is configured to perform three core control functions. First, based on the dissolved oxygen probe signal, the rate of change and standard deviation of dissolved oxygen concentration are calculated. The data processing module of control system 6 analyzes the collected dissolved oxygen time series data and uses algorithms to identify sudden change patterns in dissolved oxygen concentration, especially sudden decreases at t=15min and t=45min.

[0131] Secondly, the control system 6 controls the opening of the regulating valve 201 based on the macroscopic carbon-nitrogen ratio. By monitoring the concentration ratio of carbon and nitrogen sources in the fermenter 1 in real time, it dynamically adjusts the flow rate of the first feeding component 2 to ensure that the carbon-nitrogen ratio is maintained within the range of 18:1 during fermentation. The control system 6 adopts a PID control algorithm to precisely adjust the opening of the regulating valve 201 according to the deviation between the actual carbon-nitrogen ratio and the set value, thereby achieving stable basic feeding control.

[0132] Finally, when the rate of change of dissolved oxygen concentration exceeds a preset threshold, or when the spatial offset of dissolved oxygen concentration is greater than or equal to a preset offset threshold, the control system 6 controls one or more control valves 302 to open for pulse feeding. The preset threshold is set according to the fermentation process requirements. The preset rate of change threshold is set to 10% / min. When relative deviation is used as the spatial offset, the preset offset threshold can be 15%. When standardized deviation is used as the spatial offset, the preset offset threshold can be 1.2%. When the system detects abnormal fluctuations in dissolved oxygen concentration or a significant increase in spatial distribution differences in a local area, the control system 6 immediately activates the nozzles 301 in the corresponding area for pulse ammonia supplementation. The ammonia supplementation rate of each nozzle 301 is precisely adjusted to 2 mL / min using a PID control algorithm, with a pulse frequency of 3 times / min. This pulse feeding method can quickly respond to local nutrient deficiencies, avoiding a decrease in fermentation efficiency due to uneven nutrient distribution.

[0133] The system operates based on the close relationship between dissolved oxygen concentration and microbial metabolic activity. When microbial activity intensifies in a certain area of ​​fermenter 1, dissolved oxygen consumption in that area increases, leading to fluctuations in dissolved oxygen concentration. The system can promptly capture these changes through multi-point monitoring and achieve precise localized feeding via distributed nozzles 301, thereby maintaining a uniform distribution of nutrients and optimal microbial growth within fermenter 1. The entire system achieves multi-level control from macro-nutrient balance to micro-local regulation, significantly improving the stability and efficiency of the fermentation process.

[0134] Example 3 A fermentation system includes a fermenter 1 as the main reaction vessel. The fermenter 1 is a 500L stainless steel structure, equipped with an agitator 7 and a ventilation system. Eight dissolved oxygen probes are installed at different spatial locations within the fermenter 1, for example, vertically distributed along the central axis of the fermenter 1 at different depths of 0.2m, 0.4m, 0.6m, 0.8m, 1.0m, 1.2m, 1.4m, and 1.6m, to monitor changes in dissolved oxygen concentration in different areas in real time.

[0135] The outlet of the first feeding assembly 2 is located at the first position of fermenter 1, and is specifically used to transport a proportionally mixed carbon and nitrogen source. This pipeline adds a mixture of ammonia and acetic acid wastewater at a constant rate of 300 mL / min, with a mass ratio of ammonia to acetic acid wastewater of 1:4, achieving continuous supply of basic nutrients. Six nozzles 301, each with a diameter of 1.2 mm, are evenly distributed inside fermenter 1, enabling precise feeding in localized areas. The second feeding assembly 4 is connected to multiple distributed nozzles 301.

[0136] The control system 6, as the core control unit of the system, employs an industrial control computer and establishes electrical connections with the dissolved oxygen probe, the regulating valve 201 on the first feeding assembly 2, and the control valves 302 corresponding to each nozzle 301 on the second feeding assembly 4. The control system 6 acquires signal data from each dissolved oxygen probe in real time at a frequency of 10Hz via an industrial Ethernet data acquisition device, and processes the acquired data through Ethernet transmission.

[0137] Control system 6 is configured to perform multiple intelligent control functions. First, control system 6 calculates the standard deviation and rate of change of dissolved oxygen based on the dissolved oxygen probe signal, and analyzes the collected dissolved oxygen time series data through the data processing module to identify sudden decreases in dissolved oxygen at specific time points. Second, control system 6 adjusts the supply ratio of carbon and nitrogen sources according to the macroscopic carbon-nitrogen ratio control valve 201 to maintain a carbon-nitrogen ratio of 18:1, ensuring a balanced supply of nutrients during fermentation. When the rate of change of dissolved oxygen exceeds a preset threshold, or the spatial deviation of dissolved oxygen concentration exceeds a preset deviation threshold, control system 6 immediately controls one or more control valves 302 to open for pulse feeding, triggering the nozzles 301 in the corresponding area to pulse ammonia supplementation. The ammonia supplementation rate of nozzles 301 is adjusted to 2 mL / min at a frequency of 3 times / min through a PID control algorithm.

[0138] Optionally, the control valve 302 adopts a solenoid valve structure. Solenoid valves are characterized by fast response speed and high control precision, enabling millisecond-level on / off control to ensure the accuracy and timeliness of pulse feeding. The solenoid valve generates a magnetic field through an electromagnetic coil, driving the valve core to quickly open or close, achieving precise control of the feeding flow rate.

[0139] Alternatively, control valve 302 can also be a pneumatic valve. Pneumatic valves are driven by compressed air, offering advantages such as high driving force and stable operation, making them particularly suitable for applications requiring significant opening force. The actuator of the pneumatic valve controls the opening degree of valve 302 via a pneumatic pressure signal, enabling smooth flow regulation.

[0140] This system achieves precise spatial gradient control of the nitrogen source during fermentation through the synergistic effect of multi-point dissolved oxygen monitoring and dual-channel feeding. When the system detects an abnormal dissolved oxygen concentration in a local area, it can quickly activate the nozzle 301 in the corresponding area for targeted feeding, avoiding the problems of local nutrient over- or under-nutrition that may occur with traditional uniform feeding methods. Through this intelligent control method, the system can maintain a balanced distribution of nutrients in all areas of fermenter 1, improving fermentation efficiency and product quality.

[0141] Example 4 A fermentation system includes a fermenter 1, at least two dissolved oxygen probes disposed at different spatial locations within the fermenter 1, a nozzle 301, a first feeding assembly 2, a second feeding assembly 4, and a control system 6.

[0142] Fermentation tank 1 is a cylindrical reactor with a volume of 500L, equipped with an internal agitator 7 and a ventilation system. The walls of fermentation tank 1 are 8mm thick and made of 316L stainless steel, providing excellent corrosion resistance and sealing. The top of fermentation tank 1 has multiple interfaces for connecting various sensors and pipelines.

[0143] Eight dissolved oxygen probes are vertically distributed along the central axis of fermenter 1 at different depths, for example, 0.2m, 0.4m, 0.6m, 0.8m, 1.0m, 1.2m, 1.4m, and 1.6m. Each probe operates on an electrochemical principle, enabling real-time monitoring of dissolved oxygen concentration changes in the fermentation broth. The probes are fixed to the wall of fermenter 1 via flange connections, with the sensitive membrane at the probe tip directly contacting the fermentation broth. This multi-point distributed arrangement allows for comprehensive monitoring of dissolved oxygen levels at different spatial locations within fermenter 1, providing an accurate data foundation for subsequent spatial gradient control.

[0144] The outlet of the first feeding component 2 is located at the first position of fermenter 1, specifically in the upper part of fermenter 1, and is used to transport a proportionally mixed carbon and nitrogen source. The first feeding component 2 uses a 25mm inner diameter stainless steel pipe, and is equipped with a regulating valve 201, which is an electrically operated regulating valve with precise flow control capabilities. The first feeding component 2 is connected to a storage tank containing a mixture of ammonia and acetic acid wastewater at a mass ratio of 1:4. The first feeding component 2 delivers the nutrient solution into fermenter 1 at a constant rate of 300mL / min via a peristaltic pump, ensuring a stable supply of basic nutrients during fermentation.

[0145] Six nozzles 301, each 1.2 mm in diameter, are evenly distributed at different heights and positions within the fermenter 1. Each nozzle 301 is equipped with an independent control valve 302, which uses a solenoid valve structure for fast response and precise pulse-type feeding. The nozzles 301 are fixed to the ventilation duct via threaded connections, ensuring both ventilation efficiency and precise localized feeding. A second feeding assembly 4 connects to the multiple distributed nozzles 301. The second feeding assembly 4 employs a branched design, with the main pipeline having an inner diameter of 20 mm and the branch pipelines having inner diameters of 6 mm.

[0146] The control system 6 is electrically connected to the dissolved oxygen probe, the regulating valve 201 on the first feeding assembly 2, and the control valves 302 corresponding to each nozzle 301 on the second feeding assembly 4. The control system 6 uses an industrial control computer equipped with a multi-channel data acquisition card and an industrial Ethernet communication interface. The control system 6 connects to the dissolved oxygen probe via an RS485 bus, with a data acquisition frequency of 10Hz to ensure accurate real-time dissolved oxygen data acquisition. The control system 6 controls the opening degree of the control valves 302 via a 4-20mA current signal and controls the on / off state of each control valve 302 via digital signals.

[0147] Control system 6 is configured to calculate the standard deviation and rate of change of dissolved oxygen based on dissolved oxygen probe signals. The data processing module built into control system 6 performs real-time analysis of the collected dissolved oxygen time series data, calculates the standard deviation and rate of change of dissolved oxygen concentration at each monitoring point, and provides a scientific basis for subsequent feeding decisions.

[0148] The control system 6 controls the opening of the regulating valve 201 based on the macroscopic carbon-nitrogen ratio. Based on a preset target carbon-nitrogen ratio of 18:1 and the nutritional requirements of the current fermentation stage, the control system 6 dynamically adjusts the opening of the regulating valve 201. When a deviation of the carbon-nitrogen ratio from the target value is detected, the control system 6 automatically adjusts the regulating valve 201 to increase or decrease the supply of the basic nutrient solution, ensuring a balanced nutrient ratio during fermentation.

[0149] When the rate of change exceeds a preset threshold, or the spatial offset of dissolved oxygen concentration exceeds a preset offset threshold, the control system 6 controls one or more control valves 302 to open for pulse feeding. The preset threshold is set to a rate of change exceeding 10% / min. When relative deviation is used as the spatial offset, the preset offset threshold can be 15%; when standardized deviation is used as the spatial offset, the preset offset threshold can be 1.2%. When the system detects a sudden decrease in dissolved oxygen at t=15min and t=45min, or when the spatial offset of dissolved oxygen concentration exceeds the preset offset threshold, the control system 6 immediately triggers the nozzles 301 in the corresponding area to perform pulse ammonia replenishment. The ammonia replenishment rate for pulse feeding is 2 mL / min, the frequency is 3 times / min, and the duration is automatically adjusted according to the recovery of dissolved oxygen.

[0150] Control system 6 employs a proportional-integral (PI) control algorithm, using the standard deviation as the controlled variable and the total feeding frequency or duration of the second feeding component 4 as the manipulated variable. The proportional coefficient of the PPI control algorithm is set to 0.8, and the integral time constant is set to 120 seconds. Control system 6 calculates the deviation between the dissolved oxygen standard deviation and the set value in real time, responding quickly to the current deviation through the proportional term and eliminating steady-state error through the integral term. When the standard deviation is higher than the set value, control system 6 increases the feeding frequency of the second feeding component 4 from 3 times per minute to 5 times per minute, or extends the duration of a single feeding from 2 seconds to 4 seconds. When the standard deviation is lower than the set value, control system 6 correspondingly reduces the feeding frequency or shortens the feeding duration. This closed-loop control method can accurately maintain the stability of dissolved oxygen in fermenter 1, controlling the dissolved oxygen concentration within the range of 0.8-2.5 mg / L, effectively improving fermentation efficiency and product quality.

[0151] The entire system achieves precise control of the nitrogen source spatial gradient during fermentation through the synergistic effect of multi-point dissolved oxygen monitoring, dual-channel precise feeding, and intelligent control algorithms, which significantly improves fermentation efficiency and product consistency.

[0152] Comparative Example 1 To further verify the superiority of the nitrogen source spatial gradient control method of this invention, especially to verify the necessity of "multi-point monitoring" and "dual-channel synergy," this comparative example is established. This comparative example simulates the most common traditional control strategy in industry, which relies solely on the dissolved oxygen probe signal at a single location within fermenter 1 and performs global feedback control through a single feeding point.

[0153] A traditional single-channel feeding method is adopted, in which nitrogen source (ammonia water) and carbon source (acetic acid wastewater) are mixed and injected into a 500L fermenter 1 through a single feeding point. The feeding pipeline outlet is located in the lower part of fermenter 1, 0.3m from the bottom, with a feeding rate of 300mL / min. The mass ratio of ammonia water to acetic acid wastewater is 1:4 to maintain a macroscopic carbon-nitrogen molar ratio of 18:1. Only one dissolved oxygen probe is installed in fermenter 1, located in the middle of fermenter 1 (0.8m deep), to monitor changes in dissolved oxygen concentration.

[0154] During continuous fermentation, due to the large volume of fermenter 1 and its limited stirring effect, a single feeding point cannot effectively solve the problem of uneven nitrogen source distribution within the tank. Simultaneously, single-point dissolved oxygen monitoring cannot comprehensively reflect the dissolved oxygen status in different areas of the tank, potentially leading to nitrogen deficiency or excess in certain regions. When microbial metabolic activity intensifies in a localized area, dissolved oxygen consumption increases, but due to the lack of multi-point monitoring and localized feeding capabilities, the system cannot respond promptly, resulting in significant fluctuations in dissolved oxygen concentration, asynchronous microbial metabolism, and increased local environmental pressure.

[0155] Experimental results show that under traditional single-channel feeding + single-point dissolved oxygen monitoring conditions, only a single location's dissolved oxygen concentration reading can be obtained within fermenter 1. This makes it impossible to calculate the spatial distribution of dissolved oxygen concentration or perceive metabolic differences between different areas within the fermenter. The single-point dissolved oxygen reading fluctuates significantly, with the cell growth rate fluctuating between 0.08 and 0.25 h. - ¹ The substrate conversion rate is low, with a single-cell protein yield of only 0.8 g / L / h. However, using the dual-channel and multi-point gradient control system 6 of this application, the single-cell protein yield can reach 1.5 g / L / h, thus significantly improving the yield compared to existing fermentation systems.

[0156] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A fermentation system, characterized in that, include: Fermentation tank (1); The first feeding component (2) is connected to the fermenter (1) and is used to feed a mixture of carbon source and basic nitrogen source to the fermenter (1); Multiple spraying components (3) are distributed along the axial and / or circumferential direction of the fermenter (1) and can spray a supplementary nitrogen source into the fermenter (1). Each spraying component (3) can be controlled independently. The second feeding component (4) is connected to the spraying component (3) and is used to supply the spraying component (3) with a supplementary nitrogen source; Multiple detection elements (5) are distributed in different areas within the fermenter (1) and are used to detect the dissolved oxygen concentration in the corresponding areas; The control system (6) is electrically connected to the spray assembly (3) and the detection element (5) and is configured to control the spray assembly (3) to spray a supplementary nitrogen source in the corresponding area based on the dissolved oxygen concentration.

2. The fermentation system according to claim 1, characterized in that, The control system (6) is configured to obtain the dissolved oxygen concentration change rate and / or spatial offset based on the dissolved oxygen concentration, and when it is determined that the dissolved oxygen concentration change rate is greater than or equal to a preset change rate threshold and / or the spatial offset is greater than or equal to a preset offset threshold, control the spraying assembly (3) in the corresponding area to spray a supplementary nitrogen source.

3. The fermentation system according to claim 1, characterized in that, The control system (6) controls the pulse-type injection of nitrogen source for the spraying component (3) in the corresponding area based on the dissolved oxygen concentration; And / or, the control system (6) is configured to obtain the standard deviation of dissolved oxygen concentration based on the dissolved oxygen concentration of at least two regions, and to make the spraying frequency and / or spraying duration of the spraying assembly (3) in the corresponding region positively correlated with the standard deviation.

4. The fermentation system according to claim 3, characterized in that, The spraying component (3) has a pulse spraying duration of 2 to 30 seconds per spray and a spraying flow rate of 0.05 L / h to 0.2 L / h.

5. The fermentation system according to claim 1, characterized in that, The control system (6) is also electrically connected to the first feeding component (2). The control system (6) is configured to obtain the carbon-nitrogen molar ratio in the fermenter (1), and when it is determined that the carbon-nitrogen molar ratio is greater than the preset target carbon-nitrogen ratio, control the first feeding component (2) to increase the flow rate of the mixture, and when it is determined that the carbon-nitrogen molar ratio is less than the preset target carbon-nitrogen ratio, control the first feeding component (2) to decrease the flow rate of the mixture. And / or, the amount of nitrogen source supplied by the first feeding component (2) accounts for 70%-90% of the total amount of nitrogen source required for continuous fermentation in the fermenter (1) as the basic nitrogen supply for fermentation, and the amount of nitrogen source supplied by the second feeding component (4) accounts for 10%-30% of the total amount of nitrogen source required for continuous fermentation in the fermenter (1) as the local nitrogen source compensation. And / or, the carbon-nitrogen molar ratio in the fermenter (1) is 10:1 to 20:

1.

6. The fermentation system according to any one of claims 1-5, characterized in that, The second feeding assembly (4) includes a feeding pipe (401), an air source (402), and a material source (403). The feeding pipe (401) is connected to each of the spraying assemblies (3). The air source (402) is connected to the feeding pipe (401) and is used to supply air to the feeding pipe (401). The material source (403) is connected to the feeding pipe (401) and is used to supply supplementary nitrogen to the feeding pipe (401). And / or, the spraying assembly (3) includes a nozzle (301) and a control valve (302), the nozzle (301) is located inside the fermentation tank (1), the control valve (302) is connected between the second feeding assembly (4) and the nozzle (301), and the control valve (302) is electrically connected to the control system (6); And / or, the spraying assembly (3) is provided at least at one location below the liquid surface in the fermenter (1), near the liquid surface, on the side wall of the fermenter (1), at the corner where the side wall and bottom wall of the fermenter (1) meet, and in the interlayer area between the two layers of stirring paddles (7). And / or, the fermentation system further includes a stirring paddle (7) which is rotatably disposed within the fermentation tank (1).

7. The fermentation system according to any one of claims 1-5, characterized in that, The fermentation system is used to prepare single-cell protein. Preferably, the fermentation system is used to ferment microbial cells using acetic acid-containing wastewater as a carbon source to prepare single-cell protein. And / or, the specific growth rate of the microbial cells in the fermenter (1) is 0.1 h⁻¹. -1 ~0.2h -1 .

8. A fermentation control method, characterized in that, include: Obtain the dissolved oxygen concentration in different areas of the fermenter (1), wherein a mixture of carbon source and basic nitrogen source is continuously circulated into the fermenter (1); Based on the dissolved oxygen concentration, the spraying assembly (3) in the corresponding area is controlled to spray the nitrogen source.

9. The fermentation control method according to claim 8, characterized in that, Based on the dissolved oxygen concentration, control the spraying component (3) of the corresponding area to spray supplementary nitrogen source, including: obtaining the dissolved oxygen concentration change rate and / or the spatial offset of the dissolved oxygen concentration according to the dissolved oxygen concentration, and when it is determined that the dissolved oxygen concentration change rate is greater than or equal to a preset change rate threshold and / or the spatial offset is greater than or equal to a preset offset threshold, control the spraying component (3) of the corresponding area to spray supplementary nitrogen source; And / or, based on the dissolved oxygen concentration, control the spraying assembly (3) of the corresponding area to spray a replenishing nitrogen source, including: based on the dissolved oxygen concentration, control the spraying assembly (3) of the corresponding area to pulse-type spray a replenishing nitrogen source; And / or, the fermentation control method further includes: obtaining the standard deviation of dissolved oxygen concentration based on the dissolved oxygen concentration of at least two regions, and making the spraying frequency and / or spraying duration of the spraying component (3) in the corresponding region positively correlated with the standard deviation.

10. The fermentation control method according to claim 8, characterized in that, Also includes: Obtain the carbon-nitrogen molar ratio in the fermenter (1), and when the carbon-nitrogen molar ratio is determined to be greater than the preset target carbon-nitrogen ratio, increase the flow rate of the mixture; when the carbon-nitrogen molar ratio is determined to be less than the preset target carbon-nitrogen ratio, decrease the flow rate of the mixture. And / or, the amount of nitrogen source supplied by the mixture accounts for 70%-90% of the total amount of nitrogen source required for continuous fermentation in the fermenter (1) as the basic nitrogen supply for fermentation, and the sum of the amount of nitrogen source supplied by the spraying assembly (3) accounts for 10%-30% of the total amount of nitrogen source required for continuous fermentation in the fermenter (1) as local nitrogen source compensation. And / or, the carbon-nitrogen molar ratio in the fermenter (1) is 10:1 to 20:1; And / or, the fermentation control method is used to prepare single-cell protein, preferably, the fermentation control method is used to ferment microbial cells using acetic acid-containing wastewater as a carbon source to prepare single-cell protein; And / or, the specific growth rate of the microbial cells in the fermenter (1) is 0.1 h⁻¹. -1 ~0.2h -1 .

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