Synthesis method of high-activity composite biological carbon source

Abstract

The invention relates to the technical field of sewage biochemical treatment carbon source preparation, and discloses a synthesis method of a high-activity composite biological carbon source, which comprises the following three main steps: implementation of a solid-liquid two-phase composite fermentation basic process, implementation of a multiple bacterial phase gradient permeation system and implementation of a bidirectional osmotic pressure regulation liquid phase circulation process. According to the method, a solid-phase and liquid-phase synergistic fermentation system is formed, a multi-level microbial ecological niche is formed in a solid-phase system, and meanwhile, an adjustable two-way osmotic pressure field is formed, so that directional migration and cyclic utilization of substances are realized; the technical problems of low substance conversion efficiency, obvious mass transfer obstacle, poor microbial community stability and the like in a conventional fermentation technology are effectively solved, the activity, stability and diversity of the composite biological carbon source are remarkably improved, and an efficient and economical carbon source supplement scheme is provided for sewage treatment.

Description

Technical Field

[0001] This invention relates to the field of carbon source preparation technology for wastewater biochemical treatment, and more specifically, to a method for synthesizing a highly active composite biological carbon source. Background Technology

[0002] In biological wastewater treatment, the addition of exogenous carbon sources plays a crucial role in improving nitrogen and phosphorus removal efficiency. Conventional methods for preparing biological carbon sources mainly employ a single fermentation model, which presents the following technical challenges: 1) Single fermentation methods (such as pure liquid fermentation or pure solid fermentation) do not completely transform organic waste, resulting in low carbon source utilization and insufficient activity of the final product; 2) Existing fermentation systems have a simple microbial community structure, which cannot achieve the comprehensive transformation of complex organic matter, and the carbon source components produced are simple. 3) Low mass transfer efficiency at the solid-liquid interface during conventional fermentation is a bottleneck limiting the reaction rate; 4) During fermentation, the osmotic pressure gradient is difficult to maintain, the mass migration direction is unidirectional, and the mass transfer efficiency decreases rapidly over time. 5) The fermentation system has poor stability and weak anti-interference ability, making it difficult to adapt to the treatment needs of various organic wastes.

[0003] Currently, commonly used exogenous carbon sources on the market are mainly chemically synthesized carbon sources such as methanol, ethanol, and sodium acetate. Although these have high component purity, they are also costly and lack diverse nutrient components. While biological carbon sources are widely available and inexpensive, their simple preparation processes, unstable activity, and low conversion efficiency make them unsuitable for modern wastewater treatment processes. Therefore, developing a novel method for efficiently utilizing organic waste to prepare highly active, multi-component composite biological carbon sources has significant technological value and application prospects. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for synthesizing a highly active composite biocarbon source, comprising organic waste pretreatment, solid-phase pre-fermentation, and liquid-phase primary fermentation. The method includes the following steps: Step 1: Constructing the foundation for solid-liquid two-phase composite fermentation; The carbon-nitrogen ratio of the solid phase matrix is ​​adjusted to 25-35:1, and the carbon-nitrogen ratio of the liquid phase culture medium is adjusted to 15-20:1. About 1 / 3 of the bottom part of the solid phase is immersed in the liquid phase to form a solid-liquid interface, thus establishing a material transfer channel from the solid phase to the liquid phase. Step 2: Form a multi-phase bacterial gradient permeation system in the solid phase system; This includes forming an aerobic degradation zone in the top 5-10cm region of the solid phase, a microaerobic fermentation zone in the middle 10-25cm region, and an anaerobic fermentation zone in the bottom 25-40cm region, and establishing an osmotic pressure gradient at the solid-liquid interface. Step 3: Implement bidirectional osmotic pressure regulation liquid phase circulation; An adjustable osmotic pressure field is formed on both sides of the solid-liquid interface to realize the bidirectional directional migration of substances between the solid and liquid phases. The liquid phase reactor is divided into an acidification zone, a neutralization zone, and a product accumulation zone. Fermentation broth is harvested from the product accumulation zone periodically as a composite biological carbon source product.

[0005] Preferred method: Step 1 solid-phase pre-fermentation includes: inoculating a cellulose-degrading fungus with high-efficiency cellulase activity into a solid-phase substrate, with an inoculation amount of 2-5% of the substrate dry weight; using a fermentation bed with a porous and breathable bottom plate, with the bed height controlled at 30-40cm; maintaining the temperature at 25-30℃ and the relative humidity at 80-90%, and carrying out pre-fermentation for 3-5 days.

[0006] Preferred method: The liquid-phase primary fermentation in step 1 includes: mixing fine-particle organic material with water at a ratio of 1:5-1:10 (w / v), adding ammonia nitrogen source and phosphorus source, and adjusting the initial pH value to 6.8-7.2; extracting mixed anaerobic bacteria from the anaerobic digestion system and inoculating them into the liquid culture medium at an inoculation amount of 5-10% of the liquid volume; maintaining the temperature at 35-37℃ and the pH value not lower than 6.0 for anaerobic fermentation for 5-7 days.

[0007] Preferred: The formation of the multi-phase gradient infiltration system in step 2 includes: inoculating the top region of the solid phase with a mixture of cellulose-degrading aerobic fungi to maintain the oxygen concentration in the range of 15-21%; inoculating the middle region of the solid phase with facultative anaerobic fermentation bacteria to maintain the oxygen concentration in this region in the range of 2-8%; and inoculating the bottom region of the solid phase with obligate anaerobic bacteria to maintain the oxygen concentration in this region below 2%.

[0008] Preferred method: After inoculation, spray 0.5-1% gelatin solution evenly into the solid phase system to allow it to penetrate the entire solid phase bed. During the cooling process, the gelatin gelles to form a temporary fixed network. Then, slowly lower the temperature to 20°C and maintain it for 4-6 hours before restoring it to the normal fermentation temperature.

[0009] Preferred method: The establishment of the osmotic pressure gradient in step 2 includes: adding a mixture of osmotic active substances, including low molecular weight polyethylene glycol (PEG-2000), glycerol and trehalose, to the liquid phase system at concentrations of 0.5-1.0%, 1.0-2.0% and 0.5-1.0%, respectively; spraying a solution containing a high molecular weight polymer at a concentration of 0.1-0.3% onto the upper part of the solid phase; the resulting osmotic pressure gradient is: top of solid phase (0.6-0.8 MPa) > middle of solid phase (0.4-0.6 MPa) > bottom of solid phase (0.2-0.4 MPa) > liquid phase (0.1-0.2 MPa).

[0010] Preferably, step 2 also includes the introduction of biosurfactants: inoculating the middle region of the solid phase with a strain capable of producing biosurfactants, the inoculation amount being 2-3% of the dry weight of the substrate in that region; adding a hydrophobic substrate to the system, the amount being 0.5-1% of the dry weight of the solid phase substrate, to induce the surface-active strains to produce biosurfactants.

[0011] Preferred method: The formation of the controllable osmotic pressure field in step 3 includes: preparing an osmotic conditioner solution by mixing modified starch, sodium alginate and sodium carboxymethyl cellulose in a ratio of 2:1:1; periodically adding the osmotic conditioner to the liquid phase, with an initial addition amount of 1-2% of the liquid phase volume; and injecting different concentrations of the osmotic conditioner into different depth regions of the solid phase using a multi-point syringe, with the injection amount being 5-8% of the volume of each region.

[0012] Preferred method: The realization of bidirectional directional migration of substances in step 3 includes: setting a microporous membrane filtration device at the bottom of the solid phase with a pore size of 0.5-2 μm and an area accounting for 20-30% of the total bottom area; setting a drip irrigation device at the top of the solid phase with a drip irrigation rate controlled at 5-10 mL / (L·h) and running for 8-12 hours per day; setting a selective membrane at the solid-liquid interface, which is made of polysulfone and polyvinyl alcohol composite material and prepared by phase separation method to form a composite structure containing hydrophilic micropores and hydrophobic regions.

[0013] Preferably, the formation of the liquid phase partitioned circulation system in step 3 includes: The liquid phase reactor was divided into an acidification zone (pH 5.0-6.0), a neutralization zone (pH 6.5-7.5), and a product accumulation zone (pH 7.5-8.5). The pH value of each area is maintained stable by an automatic pH control device; Three circulation pumps are set up to be responsible for the liquid circulation in the acidification zone and the bottom of the solid phase, the liquid circulation in the neutralization zone and the middle of the solid phase, and the liquid circulation in the product accumulation zone and the top of the solid phase, respectively. Fermentation broth is harvested from the product accumulation zone every 7-10 days, with the harvest amount being 30-50% of the total volume of the zone.

[0014] The beneficial effects of this invention are as follows: Improved conversion efficiency: Through the synergistic effects of solid-liquid two-phase combined fermentation, multiple microbial phase partitioning, and bidirectional osmotic pressure regulation, this method significantly improves the conversion efficiency of organic waste. Experimental data show that compared with conventional single-phase fermentation, this method increases the organic matter conversion rate by 30-50% and the carbon source recovery rate by 40-60%. This means that the same amount of organic waste can produce more bio-carbon source products.

[0015] Enhanced carbon source activity: By forming multi-level microbial niches and a complete material transformation chain, the composite biocarbon source produced by this method exhibits higher activity. Biochemical oxygen demand (BOD) measurements show that the bioavailability of this carbon source is 50-80% higher than that of conventional biocarbon sources, and it can more effectively promote microbial growth and metabolic activities.

[0016] The product boasts a diverse composition: the liquid-phase zoned circulation system enables the targeted accumulation of different metabolites, resulting in a final product containing a variety of short-chain fatty acids, medium-chain fatty acids, alcohols, amino acids, and biosurfactants. This diverse composition allows it to meet the diverse needs of microbial communities in different types of wastewater treatment systems, thus broadening its applicability.

[0017] Improved long-term stability: By employing a system-wide method for maintaining long-term stability, this approach addresses the issues of unstable activity and short shelf life of conventional biological carbon sources. Tests show that after 90 days of storage at room temperature, this composite biological carbon source retains over 80% of its original activity, while conventional biological carbon sources typically experience activity reduction to below 50% after 30 days.

[0018] Enhanced nitrogen and phosphorus removal efficiency: Applying the composite biological carbon source prepared by this method to actual wastewater treatment processes can significantly improve nitrogen and phosphorus removal efficiency. Compared with conventional chemical carbon sources, under the same carbon dosage conditions, the total nitrogen removal rate is increased by 15-25%, the total phosphorus removal rate is increased by 20-30%, and the biochemical system operates more stably.

[0019] Significant economic advantages: This method uses low-value organic waste as raw material and produces high-value products through efficient conversion processes, significantly reducing carbon source costs. Economic benefit analysis shows that compared with commercially available chemical carbon sources, the unit cost of the composite biological carbon source prepared by this method is reduced by 40-60%, while also reducing the burden of organic waste disposal and achieving resource recycling.

[0020] Wide range of applicable wastes: Thanks to the adaptability of the multi-phase microbial gradient infiltration system, this method can treat a variety of organic wastes, including food processing waste, agricultural and forestry waste, municipal sludge, etc., which has a wide range of raw material applicability and improves the practical value of the method.

[0021] The system has strong anti-interference ability: Through dynamic regulation of microbial community structure and anti-interference ability enhancement technology, the fermentation system formed by this method has strong anti-interference ability and can adapt to fluctuations in raw material composition, environmental temperature and other factors, and maintain stable product quality.

[0022] In summary, the high-activity composite biological carbon source synthesis method provided by this invention, through the synergistic application of three-stage technologies, successfully solves the technical problems of low conversion efficiency and unstable activity in conventional biological carbon source preparation. The resulting composite biological carbon source has the advantages of high activity, diverse components, and long-lasting effect, providing an efficient and economical carbon source supplementation solution for the field of wastewater biological treatment. Attached Figure Description

[0023] Figure 1 This is a graph showing the trend of organic matter conversion rate according to the present invention; Figure 2 This is a product component distribution diagram of the present invention. Detailed Implementation

[0024] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, some features described in the examples may be combined in other examples.

[0025] Example 1 A method for synthesizing a highly active composite biocarbon source includes organic waste pretreatment, solid-phase pre-fermentation, and liquid-phase primary fermentation. The method comprises the following steps: Step 1: Constructing the foundation for solid-liquid two-phase composite fermentation; The carbon-nitrogen ratio of the solid phase matrix was adjusted to 25:1, and the carbon-nitrogen ratio of the liquid phase culture medium was adjusted to 15:1. About one-third of the bottom part of the solid phase was immersed in the liquid phase to form a solid-liquid interface, thus establishing a material transfer channel from the solid phase to the liquid phase. Solid-phase pre-fermentation includes: inoculating a cellulose-degrading fungus with high cellulase activity into a solid substrate at an inoculation amount of 2% of the substrate dry weight; using a fermentation bed with a porous and breathable bottom plate, with the bed height controlled at 30cm; maintaining a temperature of 25℃ and a relative humidity of 80% for a pre-fermentation period of 3 days. The liquid-phase primary fermentation process includes: mixing fine-particle organic material with water at a ratio of 1:5 (w / v), adding ammonia nitrogen source and phosphorus source, and adjusting the initial pH value to 6.8; extracting mixed anaerobic bacteria from the anaerobic digestion system and inoculating them into the liquid culture medium at an inoculation amount of 5% of the liquid volume; maintaining the temperature at 35℃ and the pH value not lower than 6.0 for 5 days of anaerobic fermentation.

[0026] Step 2: Form a multi-phase bacterial gradient permeation system in the solid phase system; This includes forming an aerobic degradation zone in the top 5cm region of the solid phase, a microaerobic fermentation zone in the middle 10cm region, and an anaerobic fermentation zone in the bottom 25cm region, and establishing an osmotic pressure gradient at the solid-liquid interface. The formation of the multi-phase gradient infiltration system includes: inoculating the top region of the solid phase with a mixture of cellulose-degrading aerobic fungi to maintain an oxygen concentration within 15%; inoculating the middle region of the solid phase with facultative anaerobic fermenting bacteria to maintain an oxygen concentration within 2%; and inoculating the bottom region of the solid phase with obligate anaerobic bacteria to maintain an oxygen concentration below 2%. After inoculation, a 0.5% gelatin solution is evenly sprayed into the solid-phase system to allow it to penetrate the entire solid-phase bed. During the cooling process, the gelatin gels to form a temporary fixed network. Then, the temperature is slowly lowered to 20°C and maintained for 4 hours before being restored to the normal fermentation temperature. The establishment of the osmotic pressure gradient includes: adding a mixture of osmotic active substances, including low molecular weight polyethylene glycol (PEG-2000), glycerol, and trehalose, to the liquid phase system at concentrations of 0.5%, 1.0%, and 0.5%, respectively; spraying a solution containing a high molecular weight polymer at a concentration of 0.1% onto the upper part of the solid phase; the resulting osmotic pressure gradient is: top of solid phase (0.6-0.7 MPa) > middle of solid phase (0.4-0.5 MPa) > bottom of solid phase (0.2-0.3 MPa) > liquid phase (0.1-0.15 MPa); Step 2 also includes the introduction of biosurfactants: a strain capable of producing biosurfactants is inoculated in the central region of the solid phase at an inoculation amount of 2% of the dry weight of the substrate in that region; a hydrophobic substrate is added to the system at an amount of 0.5% of the dry weight of the solid phase substrate to induce the surface-active strain to produce biosurfactants.

[0027] Step 3: Implement bidirectional osmotic pressure regulation liquid phase circulation; An adjustable osmotic pressure field is formed on both sides of the solid-liquid interface to realize the bidirectional directional migration of substances between the solid and liquid phases. The liquid phase reactor is divided into an acidification zone, a neutralization zone, and a product accumulation zone. Fermentation broth is harvested from the product accumulation zone periodically as a composite biological carbon source product. The formation of an adjustable osmotic pressure field includes: preparing an osmotic conditioner solution by mixing modified starch, sodium alginate and sodium carboxymethyl cellulose in a 2:1:1 ratio; periodically adding the osmotic conditioner to the liquid phase, with an initial addition amount of 1% of the liquid phase volume; and injecting different concentrations of the osmotic conditioner into different depth regions of the solid phase using a multi-point syringe, with the injection amount being 5% of the volume of each region.

[0028] The realization of bidirectional directional migration of substances in the solid phase includes: setting a microporous membrane filtration device at the bottom of the solid phase with a pore size of 0.5 μm and an area accounting for 20% of the total bottom area; setting a drip irrigation device at the top of the solid phase with a drip irrigation rate controlled at 5 mL / (L·h) and running for 8 hours a day; and setting a selective membrane at the solid-liquid interface, which is made of a composite material of polysulfone and polyvinyl alcohol and prepared by phase separation method to form a composite structure containing hydrophilic micropores and hydrophobic regions.

[0029] The formation of a liquid-phase partitioned circulation system includes: The liquid phase reactor was divided into an acidification zone (pH 5.0-6.0), a neutralization zone (pH 6.5-7.5), and a product accumulation zone (pH 7.5-8.5). The pH value of each area is maintained stable by an automatic pH control device; Three circulation pumps are set up to be responsible for the liquid circulation in the acidification zone and the bottom of the solid phase, the liquid circulation in the neutralization zone and the middle of the solid phase, and the liquid circulation in the product accumulation zone and the top of the solid phase, respectively. Fermentation broth is harvested from the product accumulation zone every 7-10 days, with a harvest amount of 30% of the total volume of the zone.

[0030] Example 2 The difference between this embodiment and Embodiment 1 is that: Step 1: Adjust the carbon-nitrogen ratio of the solid phase matrix to 30:1 and the carbon-nitrogen ratio of the liquid phase culture medium to 18:1. Immerse about 1 / 3 of the bottom part of the solid phase into the liquid phase to form a solid-liquid interface and establish a material transfer channel from the solid phase to the liquid phase. Solid-phase pre-fermentation includes: inoculating a cellulose-degrading fungus with high cellulase activity into a solid substrate at an inoculation amount of 3% of the substrate dry weight; using a fermentation bed with a porous and breathable bottom plate, with the bed height controlled at 35cm; maintaining a temperature of 28℃ and a relative humidity of 85% for a pre-fermentation period of 4 days. The liquid-phase primary fermentation process includes: mixing fine-particle organic material with water at a ratio of 1:8 (w / v), adding ammonia nitrogen and phosphorus sources, and adjusting the initial pH to 7.0; extracting mixed anaerobic bacteria from the anaerobic digestion system and inoculating them into the liquid culture medium at an inoculation volume of 8% of the liquid volume; maintaining the temperature at 36°C and the pH at no less than 6.0 for 6 days of anaerobic fermentation.

[0031] Step 2: Form a multi-phase bacterial gradient permeation system in the solid phase system; This includes forming an aerobic degradation zone in the top 8cm region of the solid phase, a microaerobic fermentation zone in the middle 18cm region, and an anaerobic fermentation zone in the bottom 32cm region, and establishing an osmotic pressure gradient at the solid-liquid interface; The formation of the multi-phase gradient infiltration system includes: inoculating the top region of the solid phase with a mixture of cellulose-degrading aerobic fungi to maintain an oxygen concentration within 8%; inoculating the middle region of the solid phase with facultative anaerobic fermenting bacteria to maintain an oxygen concentration within 5%; and inoculating the bottom region of the solid phase with obligate anaerobic bacteria to maintain an oxygen concentration below 2%. After inoculation, a 0.8% gelatin solution is evenly sprayed into the solid-phase system to allow it to penetrate the entire solid-phase bed. During the cooling process, the gelatin gels to form a temporary fixed network. Then, the temperature is slowly lowered to 20°C and maintained for 5 hours before being restored to the normal fermentation temperature. The establishment of the osmotic pressure gradient includes: adding a mixture of osmotic active substances, including low molecular weight polyethylene glycol (PEG-2000), glycerol, and trehalose, to the liquid phase system at concentrations of 0.8%, 1.5%, and 0.8%, respectively; spraying a solution containing a high molecular weight polymer at a concentration of 0.2% onto the upper part of the solid phase; the resulting osmotic pressure gradient is: top of solid phase (0.7-0.8 MPa) > middle of solid phase (0.5-0.6 MPa) > bottom of solid phase (0.3-0.4 MPa) > liquid phase (0.15-0.2 MPa); Step 2 also includes the introduction of biosurfactants: a strain capable of producing biosurfactants is inoculated in the central region of the solid phase at an inoculation amount of 2.5% of the dry weight of the substrate in that region; a hydrophobic substrate is added to the system at an amount of 0.8% of the dry weight of the solid phase substrate to induce the surface-active strain to produce biosurfactants.

[0032] Step 3: The formation of an adjustable osmotic pressure field includes: preparing an osmotic conditioner solution by mixing modified starch, sodium alginate and sodium carboxymethyl cellulose in a 2:1:1 ratio; periodically adding the osmotic conditioner to the liquid phase, with an initial addition amount of 1.5% of the liquid phase volume; and injecting different concentrations of the osmotic conditioner into different depth regions of the solid phase using a multi-point syringe, with the injection amount being 6% of the volume of each region.

[0033] The realization of bidirectional directional migration of substances in the solid phase includes: setting a microporous membrane filtration device at the bottom of the solid phase with a pore size of 1.2 μm and an area accounting for 25% of the total bottom area; setting a drip irrigation device at the top of the solid phase with a drip irrigation rate controlled at 8 mL / (L·h) and running for 10 hours a day; and setting a selective membrane at the solid-liquid interface, which is made of polysulfone and polyvinyl alcohol composite material and prepared by phase separation method to form a composite structure containing hydrophilic micropores and hydrophobic regions.

[0034] The formation of a liquid-phase partitioned circulation system includes: The liquid phase reactor was divided into an acidification zone (pH 5.0-6.0), a neutralization zone (pH 6.5-7.5), and a product accumulation zone (pH 7.5-8.5). The pH value of each area is maintained stable by an automatic pH control device; Three circulation pumps are set up to be responsible for the liquid circulation in the acidification zone and the bottom of the solid phase, the liquid circulation in the neutralization zone and the middle of the solid phase, and the liquid circulation in the product accumulation zone and the top of the solid phase, respectively. Fermentation broth is harvested from the product accumulation zone every 9 days, with a harvest amount of 40% of the total volume of the zone.

[0035] Example 3 The difference between this embodiment and Embodiment 1 is that: Step 1: Adjust the carbon-nitrogen ratio of the solid phase matrix to 35:1 and the carbon-nitrogen ratio of the liquid phase culture medium to 20:1. Immerse about 1 / 3 of the bottom part of the solid phase into the liquid phase to form a solid-liquid interface and establish a material transfer channel from the solid phase to the liquid phase. Solid-phase pre-fermentation includes: inoculating a cellulose-degrading fungus with high cellulase activity into a solid substrate at an inoculation amount of 5% of the substrate dry weight; using a fermentation bed with a porous and breathable bottom plate, with the bed height controlled at 40cm; maintaining a temperature of 30℃ and a relative humidity of 90% for a pre-fermentation period of 5 days. The liquid-phase primary fermentation process includes: mixing fine-particle organic material with water at a ratio of 1:10 (w / v), adding ammonia nitrogen source and phosphorus source, and adjusting the initial pH value to 7.2; extracting mixed anaerobic bacteria from the anaerobic digestion system and inoculating them into the liquid culture medium at an inoculation amount of 10% of the liquid volume; maintaining the temperature at 37℃ and the pH value not lower than 6.0 for 7 days of anaerobic fermentation.

[0036] Step 2: Form a multi-phase bacterial gradient permeation system in the solid phase system; This includes forming an aerobic degradation zone in the top 10cm region of the solid phase, a microaerobic fermentation zone in the middle 25cm region, and an anaerobic fermentation zone in the bottom 40cm region, and establishing an osmotic pressure gradient at the solid-liquid interface. The formation of the multi-phase gradient infiltration system includes: inoculating the top region of the solid phase with a mixture of cellulose-degrading aerobic fungi to maintain an oxygen concentration within 21%; inoculating the middle region of the solid phase with facultative anaerobic fermenting bacteria to maintain an oxygen concentration within 2%; and inoculating the bottom region of the solid phase with obligate anaerobic bacteria to maintain an oxygen concentration below 2%. After inoculation, a 0.5% gelatin solution is evenly sprayed into the solid-phase system to allow it to penetrate the entire solid-phase bed. During the cooling process, the gelatin gels to form a temporary fixed network. Then, the temperature is slowly lowered to 20°C and maintained for 4 hours before being restored to the normal fermentation temperature. The establishment of the osmotic pressure gradient includes: adding a mixture of osmotic active substances, including low molecular weight polyethylene glycol (PEG-2000), glycerol, and trehalose, to the liquid phase system at concentrations of 0.5%, 1.0%, and 0.5%, respectively; spraying a solution containing a high molecular weight polymer at a concentration of 0.1% onto the upper part of the solid phase; the resulting osmotic pressure gradient is: top of solid phase (0.6-0.8 MPa) > middle of solid phase (0.4-0.6 MPa) > bottom of solid phase (0.2-0.4 MPa) > liquid phase (0.1-0.2 MPa); Step 2 also includes the introduction of biosurfactants: a strain capable of producing biosurfactants is inoculated in the central region of the solid phase at an inoculation amount of 2% of the dry weight of the substrate in that region; a hydrophobic substrate is added to the system at an amount of 0.5-1% of the dry weight of the solid phase substrate to induce the surface-active strain to produce biosurfactants.

[0037] Step 3: The formation of an adjustable osmotic pressure field includes: preparing an osmotic conditioner solution by mixing modified starch, sodium alginate and sodium carboxymethyl cellulose in a 2:1:1 ratio; periodically adding the osmotic conditioner to the liquid phase, with an initial addition amount of 2% of the liquid phase volume; and injecting different concentrations of the osmotic conditioner into different depth regions of the solid phase using a multi-point syringe, with the injection amount being 8% of the volume of each region.

[0038] The realization of bidirectional directional migration of substances in the solid phase includes: setting a microporous membrane filtration device at the bottom of the solid phase with a pore size of 2 μm and an area accounting for 30% of the total bottom area; setting a drip irrigation device at the top of the solid phase with a drip irrigation rate controlled at 10 mL / (L·h) and running for 12 hours a day; and setting a selective membrane at the solid-liquid interface, which is made of a composite material of polysulfone and polyvinyl alcohol and prepared by phase separation method to form a composite structure containing hydrophilic micropores and hydrophobic regions.

[0039] Fermentation broth is harvested from the product accumulation zone every 10 days, with a harvest amount of 50% of the total volume of the zone.

[0040] Example 4 The method for synthesizing a highly active composite biocarbon source proposed in this embodiment includes the following specific steps: 1. Implementation of basic solid-liquid two-phase composite fermentation process 1.1 Raw material pretreatment Select organic waste (such as food processing waste, agricultural and forestry waste, municipal sludge, etc.) as the fermentation substrate and pretreat it according to the following steps: Physical sorting: The raw materials are crushed and screened to select materials with a particle size of 5-20 mm as solid-phase fermentation substrate, and fine particles with a particle size of less than 5 mm are used to prepare liquid-phase fermentation culture medium. Adjusting the carbon-nitrogen ratio: The carbon and nitrogen content in the raw materials is measured. By mixing different types of organic waste, the carbon-nitrogen ratio of the solid matrix is ​​controlled within the range of 25-35:1, and the carbon-nitrogen ratio of the liquid culture medium is controlled within the range of 15-20:1. Moisture adjustment: Adjust the moisture content of the solid substrate to 60-65% to create suitable conditions for subsequent solid-phase fermentation.

[0041] 1.2 Implementation of Solid-Phase Pre-Fermentation Inoculation with fungal agents: Select cellulose-degrading fungi with high cellulase activity (including white-rot fungi such as Phanerochaete chrysosporium, Trametes versicolor, and brown-rot fungi such as Gloeophyllum trabeum, mixed in a 1:1:1 ratio) and inoculate them into the solid substrate at an inoculation amount of 2-5% of the dry weight of the substrate; Solid-phase fermentation device assembly: A fermentation bed with a porous and breathable bottom plate is used, and the bed height is controlled at 30-40cm to ensure that oxygen can permeate appropriately and form an oxygen concentration gradient; Initial fermentation parameters control: Maintain the temperature at 25-30℃ and the relative humidity at 80-90% for 3-5 days of pre-fermentation to promote fungal growth and begin to decompose the complex polysaccharides in the solid matrix.

[0042] 1.3 Implementation of Liquid-Phase Primary Fermentation Preparation of liquid culture medium: Mix fine organic material with water at a ratio of 1:5-1:10 (w / v), add appropriate amounts of ammonia nitrogen source (such as ammonium sulfate) and phosphorus source (such as potassium dihydrogen phosphate), and adjust the initial pH value to 6.8-7.2; Anaerobic bacterial inoculation: Extract mixed anaerobic bacteria from a mature anaerobic digestion system and inoculate them into liquid culture medium at a volume of 5-10% of the liquid volume; Liquid phase reactor assembly: A stirred reactor with a gas collection device at the top is adopted. The working volume is 1.5-2 times the solid phase volume. The stirring speed is controlled at 50-100 rpm to ensure uniform mixing without causing violent disturbance. Initial stage parameter control of liquid-phase fermentation: maintain the temperature at 35-37℃, allow the pH value to change naturally but not lower than 6.0, and carry out anaerobic fermentation for 5-7 days to promote the conversion of organic matter into short-chain fatty acids.

[0043] 1.4 Implementation of Solid-Liquid Phase Bonding and Product Reflux Solid-liquid interface contact method: A semi-immersion contact method is adopted, in which about 1 / 3 of the bottom part of the solid phase is immersed in the liquid phase to form a stable solid-liquid interface; Liquid-phase product circulation operation: Set up a liquid-phase product pumping device to slowly spray the fermentation broth in the liquid phase onto the solid phase surface at a rate of 10-20 mL / (L·h) to form a liquid permeation flow from top to bottom. Reflux control strategy: Intermittent reflux is adopted, with each reflux lasting 2-4 hours and an interval of 8-12 hours, to ensure that the solid phase has sufficient time to absorb and transform the products in the liquid phase.

[0044] The solid-liquid two-phase composite fermentation process implemented through the above steps achieves synergistic effects between the solid and liquid phases, laying the foundation for the subsequent implementation of a multi-phase gradient osmosis system and a bidirectional osmotic pressure-controlled liquid-phase circulation process. Unlike conventional single-phase fermentation, this process integrates two fermentation modes, significantly improving the material conversion efficiency and product diversity of the fermentation system.

[0045] 2. Implementation of a multi-phase microbial gradient infiltration system After 7-10 days of operation of the basic solid-liquid two-phase combined fermentation process, the multi-phase microbial gradient osmosis system implementation stage begins. At this stage, preliminary fungal growth has formed in the solid phase, and short-chain fatty acids begin to accumulate in the liquid phase. The main purpose of this stage is to establish multi-level microbial niches in the solid-phase system and simultaneously introduce osmotic pressure gradient mass transfer methods to achieve directional migration of substances.

[0046] 2.1 Formation of multiple bacterial communities This step, through precise inoculation methods and controlled environmental conditions, establishes three layers of microbial niches in the solid-phase system. The specific operation is as follows: Formation of the top aerobic zone: A pre-cultured mixture of cellulose-degrading aerobic fungi (containing white-rot fungi such as *Phanerochaete chrysosporium*, *Trametes versicolor*, and *Aspergillus niger*, mixed in a 1:1:1 ratio) is sprayed onto the top 5-10 cm of the solid-phase fermentation bed. The inoculum size is 3-5% of the dry weight of the substrate in this area. Good aeration is maintained in this area, with the oxygen concentration kept within the range of 15-21%, thus forming an aerobic degradation zone. Formation of the middle microaerophilic zone: Pre-cultured facultative anaerobic fermentation bacteria (including Lactobacillus spp., Leuconostoc spp., and Clostridium spp., mixed in a 2:1:2 ratio) are inoculated into the middle 10-25 cm region of the solid-phase fermentation bed via injection, with an inoculation amount of 4-6% of the dry weight of the substrate in this region. By controlling the aeration rate, the oxygen concentration in this region is maintained within the range of 2-8%, thus forming a microaerophilic fermentation zone. Formation of the bottom anaerobic zone: Pre-cultured obligate anaerobic bacteria (including methanogens such as Methanobacterium spp., hydrogen-producing bacteria such as Clostridium butyricum, and acetogens such as Acetobacterium spp., mixed in a 1:2:2 ratio) are inoculated into the bottom 25-40 cm area of ​​the solid-phase fermentation bed via injection, with an inoculation amount of 5-8% of the dry weight of the substrate in this area. This area is partially submerged in the liquid phase, naturally forming an anaerobic environment with an oxygen concentration of less than 2%, thus creating the anaerobic fermentation zone.

[0047] Microbial spatial stabilization treatment: After inoculation, a 0.5-1% gelatin solution is evenly sprayed into the solid-phase system, allowing it to penetrate the entire solid-phase bed. During cooling, the gelatin gelles to form a temporary immobilization network. The temperature is then slowly lowered to 20°C and maintained for 4-6 hours before being restored to normal fermentation temperature. This process temporarily immobilizes microorganisms in their respective areas, preventing rapid migration and mixing, and providing time for the formation of stable stratified niches.

[0048] 2.2 Implementation of Osmotic Gradient Mass Transfer System This step establishes an osmotic pressure gradient to enable the directional migration of substances between the solid and liquid phases, thereby enhancing mass transfer efficiency. Addition of osmotic active substances: A mixture of osmotic active substances, including low molecular weight polyethylene glycol (PEG-2000), glycerol, and trehalose, is added to the liquid phase system at concentrations of 0.5-1.0%, 1.0-2.0%, and 0.5-1.0%, respectively. These substances create a high osmotic pressure environment (0.1-0.2 MPa) in the liquid phase, forming a pressure difference with the low osmotic pressure region in the solid phase, thus promoting the migration of substances from the solid phase to the liquid phase. Solid phase osmotic conditioning: Spray a solution containing high molecular weight polymers (such as polyacrylamide, concentration 0.1-0.3%) onto the upper part of the solid phase. These high molecular weight substances can form a high osmotic pressure zone in the upper part of the solid phase, promoting the migration of water and low molecular weight substances in the liquid phase to the upper part of the solid phase. Osmotic pressure gradient stabilization: By periodically monitoring the osmotic pressure changes at different depths in the solid phase and the liquid phase, the amount and frequency of addition of osmotic active materials are adjusted based on the measurement results to maintain a stable osmotic pressure gradient. Under typical conditions, the resulting osmotic pressure gradient is: top of solid phase (0.6-0.8 MPa) > middle of solid phase (0.4-0.6 MPa) > bottom of solid phase (0.2-0.4 MPa) > liquid phase (0.1-0.2 MPa).

[0049] 2.3 Methods for introducing biosurfactants To address the challenge of mass transfer in solid-liquid two-phase systems involving hydrophobic substances, this step introduces a biosurfactant: Inoculation with surfactant strains: Select strains capable of producing biosurfactants (such as *Candida lipolytica* and *Pseudomonas fluorescens*, mixed in a 1:1 ratio), and inoculate them in the central region of the solid phase, with an inoculation amount of 2-3% of the dry weight of the substrate in that region; Surfactant generation induction: Adding a small amount of hydrophobic substrate (such as vegetable oil, at a concentration of 0.5-1% of the dry weight of the solid matrix) to the system induces surface-active strains to produce biosurfactants (mainly including rhamnolipids, lipopeptides, and glycerides). These surfactants can reduce the solid-liquid interfacial tension and increase the mass transfer rate of hydrophobic substances. Surfactant recycling: A foam separation device is set up in the liquid phase system to periodically collect the foam enriched by biosurfactants. After simple treatment, the foam is reintroduced into the system to realize the recycling of surfactants.

[0050] Through the above operations, the implemented multi-phase microbial gradient infiltration system exhibits the following characteristics: spatially, it creates a gradient distribution from aerobic to microaerophilic to anaerobic, allowing microorganisms with different functions to grow and reproduce in their respective suitable areas, forming a material transformation chain; osmotic pressure gradients are established for material migration, promoting the directional migration of substances between the solid and liquid phases; and the introduction of biosurfactants improves the mass transfer efficiency of hydrophobic substances. These technical steps work together to significantly enhance the conversion efficiency of organic waste and the diversity of products.

[0051] 3. Implementation of the bidirectional osmotic pressure regulation liquid phase circulation process After the multi-phase gradient osmosis system has been running stably for 10-15 days, the third technical stage of this method begins: implementation of the bidirectional osmotic pressure control liquid-phase circulation process. The core objective of this stage is to create a controllable osmotic pressure field, enabling bidirectional directional migration of substances between the solid and liquid phases, establishing a material recycling pathway, and maintaining the system's long-term stable material transfer efficiency.

[0052] 3.1 Formation of an adjustable osmotic pressure field This step achieves bidirectional directional migration of substances by creating an adjustable osmotic pressure field on both sides of the solid-liquid interface: Preparation of polymeric osmotic conditioner: Select biocompatible and biodegradable polymeric materials such as modified starch, sodium alginate and sodium carboxymethyl cellulose, mix them in a ratio of 2:1:1, and prepare a 2-5% (w / v) solution as an osmotic conditioner; Liquid phase osmotic pressure control: The above-mentioned osmotic regulator is added to the liquid phase periodically. The initial addition amount is 1-2% of the liquid phase volume. Subsequently, according to the osmotic pressure monitoring results, it is replenished every 3-5 days to maintain the liquid phase osmotic pressure in the range of 0.1-0.2 MPa. Regional control of solid phase osmotic pressure: Injecting different concentrations of osmotic regulators into different depth regions of the solid phase: Using a multi-point syringe, inject a regulator with a concentration of 3-5% into the top region (0-10cm), a regulator with a concentration of 2-3% into the middle region (10-25cm), and a regulator with a concentration of 1-2% into the bottom region (25-40cm). The injection volume of each region is 5-8% of the volume of each region, forming an osmotic pressure gradient from the top to the bottom. Osmotic pressure dynamic monitoring and adjustment: Using micro osmotic pressure sensors, which are buried at different depths in the solid phase and in the liquid phase, the osmotic pressure changes are monitored in real time. Based on the monitoring results, the amount and location of the osmotic conditioner are adjusted every 5-7 days to ensure the stability of the osmotic pressure gradient.

[0053] 3.2 Formation of a two-way directional migration system for matter Based on the formation of an adjustable osmotic pressure field, this step creates a bidirectional directional migration system for matter: Solid-to-liquid phase migration channel: Multiple microporous membrane filtration devices with pore sizes of 0.5-2μm and an area accounting for 20-30% of the total bottom area are set at the bottom of the solid phase, allowing low molecular weight products (such as short-chain fatty acids, amino acids, etc.) in the solid phase to migrate directionally to the liquid phase under the action of osmotic pressure difference; Liquid-to-solid phase migration channel: A drip irrigation device is installed at the top of the solid phase. Combined with the osmotic pressure gradient formed earlier, it promotes the migration of water and nutrients in the liquid phase to the upper part of the solid phase. The drip irrigation rate is controlled at 5-10 mL / (L·h), and it runs for 8-12 hours per day. Selective control of migrating substances: A selective membrane is constructed at the solid-liquid interface. This membrane is made of a polysulfone and polyvinyl alcohol composite material (mass ratio 3:1) and prepared by phase separation. It forms a composite structure containing hydrophilic micropores (pore size 0.2-0.5 μm) and hydrophobic regions, selectively allowing different types of substances to pass through. For example, it allows the bidirectional migration of small-molecule organic acids (molecular weight <200 Da) and amino acids, while restricting the migration of large-molecule polysaccharides and proteins (molecular weight >1000 Da). 3.3 Formation of the liquid phase zoned circulation system To achieve the targeted accumulation and separation of different metabolites, this step establishes a liquid-phase partitioned circulation system: Liquid phase partitioning: The liquid phase reactor is divided into three functional zones: an acidification zone (pH 5.0-6.0), a neutralization zone (pH 6.5-7.5), and a product accumulation zone (pH 7.5-8.5). An automatic pH control system (including pH electrodes, a microcomputer controller, and a peristaltic pump) maintains stable pH values ​​in each zone. The pH in the acidification zone is controlled by automatically adding dilute hydrochloric acid (0.1 mol / L), the pH in the neutralization zone is controlled by adding sodium bicarbonate solution (5% w / v), and the pH in the product accumulation zone is controlled by adding sodium hydroxide solution (0.1 mol / L). Liquid-phase directional circulation: Three circulation pumps are set up to handle the liquid circulation paths from the acidification zone to the bottom of the solid phase, the neutralization zone to the middle of the solid phase, and the product accumulation zone to the top of the solid phase, respectively. The circulation rates are 15-20, 10-15, and 5-10 mL / (L·h). Selective accumulation of products: short-chain fatty acids (such as acetic acid, propionic acid, butyric acid, etc.) mainly accumulate in the acidification zone, medium-chain fatty acids and alcohols mainly accumulate in the neutralization zone, and highly active substances such as amino acids, peptides and biosurfactants mainly accumulate in the product accumulation zone. Product harvesting: Fermentation broth is harvested from the product accumulation area every 7-10 days, with a harvest volume of 30-50% of the total volume of the area. After harvesting, an equal amount of fresh culture medium is added. The harvested fermentation broth, after simple processing, becomes a highly active composite biocarbon source product.

[0054] 3.4 Methods for Maintaining Long-Term System Stability To ensure the long-term stable operation of the entire system, the following technical methods are used in this step: Degradation control of polymeric osmotic regulators: Introduce microorganisms (such as Bacillus spp., which produces amylase) into the system to control their biomass, so that the degradation rate and replenishment rate of the osmotic regulators are balanced, and the long-term stability of the osmotic pressure gradient is maintained. Dynamic regulation of microbial community structure: Real-time quantitative PCR technology was used to monitor changes in the microbial community structure of each region every 7 days. Quantitative analysis of 16S rRNA and 18S rRNA genes was performed. When the proportion of certain functional bacteria (such as cellulose-degrading bacteria, acid-producing bacteria, etc.) decreased by more than 30%, the corresponding strains were added in time (the inoculum amount was 1-2% of the dry weight of the substrate in that region) to ensure the stability of the multiple microbial gradient. Enhanced resistance to interference: Introducing stress-resistant strains and tolerance-enhancing substances (such as betaine and proline) into the system improves its adaptability to environmental factors such as temperature fluctuations and pH changes. Byproduct accumulation control: Set up a byproduct degradation and circulation system to periodically convert or remove byproducts that may inhibit the fermentation process (such as sulfides, excess ammonia nitrogen, etc.) to prevent them from accumulating in the system to the inhibitory concentration.

[0055] Through the implementation of the aforementioned bidirectional osmotic pressure-controlled liquid-phase circulation process, this method achieves the full conversion of complex components in organic waste, producing a diverse and long-lasting composite biocarbon source. This process achieves a controllable osmotic pressure field, enabling bidirectional directional migration of substances; it forms a liquid-phase zoned circulation system, achieving the directional accumulation of different metabolites; and it employs a long-term system stability maintenance method to ensure the continuous and stable operation of the entire process.

[0056] Experimental verification Experiments were conducted to verify the effect of the multi-microbial gradient osmosis system on improving the conversion efficiency of organic matter.

[0057] Experiment: The effect of a multi-phase microbial gradient osmosis system on organic matter conversion efficiency 1. Experimental Design This experiment aimed to compare the effects of three different fermentation systems on the conversion efficiency of organic waste: - System A: Traditional single-phase liquid fermentation system (control group 1) - System B: Traditional solid-liquid two-phase fermentation system with aseptic phase gradient (control group 2) - System C: The multi-phase microbial gradient permeation system of this invention 2. Experimental Materials Organic waste: a mixture of food processing waste and agricultural and forestry waste, with a total organic carbon content of 45±2% and a total nitrogen content of 1.5±0.2%. Inoculation strain: Cellulose-degrading fungal mixed inoculum (white rot fungus Phanerochaete chrysosporium, Trametesversicolor, and brown rot fungus Gloeophyllum trabeum, mixed in a 1:1:1 ratio). Facultative anaerobic fermenting bacteria (Lactobacillus spp., Leuconostoc spp., and Clostridium spp., mixed in a 2:1:2 ratio); Obligate anaerobic bacteria (a mixture of methanogens Methanobacterium spp., hydrogen-producing bacteria Clostridium butyricum, and acetogens Acetobacterium spp. in a 1:2:2 ratio). Penetration-active ingredients: low molecular weight polyethylene glycol (PEG-2000), glycerin, and trehalose; Analytical instruments: Total organic carbon analyzer, gas chromatograph, high performance liquid chromatograph.

[0058] 3. Experimental Procedure 3.1 System Construction System A (traditional single-phase liquid fermentation): 1. Crush organic waste to a particle size of <5mm and mix it with water at a ratio of 1:8 (w / v); 2. Adjust the carbon-to-nitrogen ratio to 20:1 and the pH value to 7.0; 3. Inoculate with a mixed anaerobic bacterial culture, at a volume of 5% of the liquid volume; 4. Anaerobic fermentation is carried out in a closed reactor at a temperature of 35°C for 30 days.

[0059] System B (Traditional solid-liquid two-phase fermentation): 1. Organic waste is divided into two parts: particles with a diameter of 5-20 mm are used as the solid phase matrix, and particles with a diameter of <5 mm are used to prepare the liquid phase culture medium; 2. Adjust the carbon-to-nitrogen ratio of the solid-phase substrate to 30:1 and the water content to 60%; adjust the carbon-to-nitrogen ratio of the liquid-phase culture medium to 20:1. 3. Inoculate cellulose-degrading fungi in the solid phase and inoculate a mixed anaerobic bacterial community in the liquid phase; 4. Immerse the bottom 1 / 3 of the solid phase into the liquid phase, but do not construct a microbial gradient or regulate osmotic pressure; 5. Ferment at 30℃ for 30 days.

[0060] System C (Multiple Microbial Phase Gradient Permeation System): 1. Construct the basic solid-liquid two-phase composite fermentation process and the multiple microbial phase gradient permeation system according to steps 4.1 to 4.2 in Embodiment 1 of the present invention; 2. Inoculate different regions of the solid phase with corresponding bacterial groups to create a bacterial gradient; 3. Add osmotic active substances to establish an osmotic pressure gradient; 4. Ferment for 30 days under the same conditions.

[0061] 3.2 Detection Method Organic matter conversion rate determination: Samples were taken every 5 days to determine the total organic carbon content remaining in each system. Calculation formula: Organic matter conversion rate (%) = (Initial TOC - Residual TOC) / Initial TOC × 100%; Product composition analysis: Samples were taken every 5 days to analyze the content of short-chain fatty acids, alcohols, and amino acids produced in each system. Short-chain fatty acids were determined by gas chromatography. Alcohols and amino acids were determined by high performance liquid chromatography.

[0062] Carbon source recovery rate calculation: Carbon source recovery rate (%) = Total carbon content in product / Total carbon content in raw material × 100%; 4. Experimental Results 4.1 Comparison of Organic Matter Conversion Rates The organic matter conversion rates of the three fermentation systems during the 30-day fermentation process are shown in the table below:

[0063] Figure 1 : Trend chart of organic matter conversion rate.

[0064] 4.2 Product Composition Analysis The contents of the main product components produced by the three systems after 30 days of fermentation are shown in the table below:

[0065] Figure 2 Product component distribution diagram.

[0066] 4.3 Comparison of carbon source recovery rates The carbon source recovery rates of the three systems are shown in the table below:

[0067] 4.4 Results Analysis The experimental results show that: Organic matter conversion rate: The organic matter conversion rate of System C (multi-phase gradient osmosis system) reached 79.4% after 30 days of fermentation, which was 27.1 percentage points higher than that of System A (traditional single-phase liquid fermentation), with an improvement rate of 52.8%; and 17.7 percentage points higher than that of System B (traditional solid-liquid two-phase fermentation), with an improvement rate of 28.7%.

[0068] Product composition diversity: The content of various product components produced by system C is significantly higher than that of system A and system B. In particular, the total amount of amino acids is 4 times that of system A and 2.1 times that of system B, indicating that the multi-phase gradient osmosis system can more comprehensively transform organic matter and produce more abundant metabolites.

[0069] Carbon source recovery rate: The carbon source recovery rate of system C reached 76.0%, which is 32 percentage points higher than that of system A (72.7% improvement rate) and 20 percentage points higher than that of system B (35.7% improvement rate). This indicates that the multi-microbial gradient infiltration system can more effectively convert carbon elements in organic waste into valuable biological carbon source products.

[0070] In summary, the experimental results demonstrate that the multi-phase gradient permeation system of the present invention is significantly superior to traditional fermentation methods in terms of organic matter conversion efficiency, product diversity, and carbon source recovery rate, thus verifying the technical effectiveness of the present invention.

[0071] The embodiments of the present invention have been described above. However, the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make more equivalent embodiments under the guidance of the present embodiments, and all of them are within the protection scope of the present embodiments.

Claims

1. A method for synthesizing a highly active composite biocarbon source, comprising organic waste pretreatment, solid-phase pre-fermentation, and liquid-phase main fermentation, characterized in that, The method includes the following steps: Step 1: Constructing the foundation for solid-liquid two-phase composite fermentation; The carbon-nitrogen ratio of the solid phase matrix is ​​adjusted to 25-35:1, and the carbon-nitrogen ratio of the liquid phase culture medium is adjusted to 15-20:

1. About 1 / 3 of the bottom part of the solid phase is immersed in the liquid phase to form a solid-liquid interface, thus establishing a material transfer channel from the solid phase to the liquid phase. Step 2: Form a multi-phase bacterial gradient permeation system in the solid phase system; This includes forming an aerobic degradation zone in the top 5-10cm region of the solid phase, a microaerobic fermentation zone in the middle 10-25cm region, and an anaerobic fermentation zone in the bottom 25-40cm region, and establishing an osmotic pressure gradient at the solid-liquid interface. Step 3: Implement bidirectional osmotic pressure regulation liquid phase circulation; An adjustable osmotic pressure field is formed on both sides of the solid-liquid interface to realize the bidirectional directional migration of substances between the solid and liquid phases. The liquid phase reactor is divided into an acidification zone, a neutralization zone, and a product accumulation zone. Fermentation broth is harvested from the product accumulation zone periodically as a composite biological carbon source product.

2. The method for synthesizing a highly active composite biocarbon source according to claim 1, characterized in that, Step 1, solid-phase pre-fermentation, includes: inoculating a cellulose-degrading fungus with high-efficiency cellulase activity into a solid substrate, with an inoculation amount of 2-5% of the substrate dry weight; using a fermentation bed with a porous and breathable bottom plate, with the bed height controlled at 30-40 cm; maintaining a temperature of 25-30℃ and a relative humidity of 80-90%, and carrying out pre-fermentation for 3-5 days.

3. The method for synthesizing a highly active composite biocarbon source according to claim 1, characterized in that, Step 1, the liquid-phase primary fermentation, includes: mixing fine-particle organic material with water at a ratio of 1:5 to 1:10 (w / v), adding ammonia nitrogen source and phosphorus source, and adjusting the initial pH value to 6.8-7.2; extracting mixed anaerobic bacteria from the anaerobic digestion system and inoculating them into the liquid culture medium at an inoculation amount of 5-10% of the liquid volume; maintaining the temperature at 35-37℃ and the pH value not lower than 6.0 for anaerobic fermentation for 5-7 days.

4. The method for synthesizing a highly active composite biocarbon source according to claim 1, characterized in that, The formation of the multi-phase gradient infiltration system in step 2 includes: inoculating the top region of the solid phase with a mixture of cellulose-degrading aerobic fungi to maintain an oxygen concentration in the range of 15-21%; inoculating the middle region of the solid phase with facultative anaerobic fermentation bacteria to maintain an oxygen concentration in the range of 2-8%; and inoculating the bottom region of the solid phase with obligate anaerobic bacteria to maintain an oxygen concentration in the region below 2%.

5. The method for synthesizing a highly active composite biocarbon source according to claim 4, characterized in that, After inoculation, spray 0.5-1% gelatin solution evenly into the solid phase system to allow it to penetrate the entire solid phase bed. During the cooling process, the gelatin gelles to form a temporary fixed network. Then, slowly lower the temperature to 20°C and maintain it for 4-6 hours before restoring it to the normal fermentation temperature.

6. The method for synthesizing a highly active composite biocarbon source according to claim 1, characterized in that, The establishment of the osmotic pressure gradient in step 2 includes: adding a mixture of osmotic active substances, including low molecular weight polyethylene glycol, glycerol and trehalose, to the liquid phase system at concentrations of 0.5-1.0%, 1.0-2.0% and 0.5-1.0%, respectively; spraying a solution containing a high molecular weight polymer at a concentration of 0.1-0.3% onto the upper part of the solid phase; the resulting osmotic pressure gradient is: top of solid phase > middle of solid phase > bottom of solid phase > liquid phase.

7. The method for synthesizing a highly active composite biocarbon source according to claim 1, characterized in that, Step 2 also includes the introduction of biosurfactants: inoculating the middle region of the solid phase with a strain capable of producing biosurfactants, the inoculation amount being 2-3% of the dry weight of the substrate in that region; adding a hydrophobic substrate to the system, the amount being 0.5-1% of the dry weight of the solid phase substrate, to induce the surface-active strains to produce biosurfactants.

8. The method for synthesizing a highly active composite biocarbon source according to claim 1, characterized in that, The formation of the controllable osmotic pressure field in step 3 includes: preparing an osmotic conditioner solution by mixing modified starch, sodium alginate and sodium carboxymethyl cellulose in a ratio of 2:1:1; periodically adding the osmotic conditioner to the liquid phase, with an initial addition amount of 1-2% of the liquid phase volume; and injecting different concentrations of the osmotic conditioner into different depth regions of the solid phase using a multi-point syringe, with the injection amount being 5-8% of the volume of each region.

9. The method for synthesizing a highly active composite biocarbon source according to claim 1, characterized in that, The realization of bidirectional directional migration of substances in step 3 includes: setting a microporous membrane filtration device at the bottom of the solid phase with a pore size of 0.5-2 μm and an area accounting for 20-30% of the total bottom area; setting a drip irrigation device at the top of the solid phase with a drip irrigation rate controlled at 5-10 mL / (L·h) and running for 8-12 hours per day; and setting a selective membrane at the solid-liquid interface, which is made of polysulfone and polyvinyl alcohol composite material and prepared by phase separation method to form a composite structure containing hydrophilic micropores and hydrophobic regions.

10. The method for synthesizing a highly active composite biocarbon source according to claim 1, characterized in that, The formation of the liquid phase partitioned circulation system in step 3 includes: The liquid phase reactor is divided into an acidification zone, a neutralization zone, and a product accumulation zone; The pH value of each area is maintained stable by an automatic pH control device; Three circulation pumps are set up to be responsible for the liquid circulation in the acidification zone and the bottom of the solid phase, the liquid circulation in the neutralization zone and the middle of the solid phase, and the liquid circulation in the product accumulation zone and the top of the solid phase, respectively. Fermentation broth is harvested from the product accumulation zone every 7-10 days, with the harvest amount being 30-50% of the total volume of the zone.

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