Preparation method and application of high-efficiency composite biological carbon source

Abstract

The application relates to the technical field of sewage biochemical treatment, and discloses a preparation method of a high-efficiency composite biological carbon source, which comprises solid-liquid two-phase fermentation treatment, microbial community gradient relay treatment, fermentation liquid backflow and biological detoxification system and biomass enhancement treatment; the application realizes the preparation of the high-concentration (COD >= 50,000 mg / L), high-stability (stably running time >= 120 days) and high-activity composite biological carbon source by combining solid-state fermentation and liquid-state fermentation, constructing a microbial gradient metabolic network, applying a porous carrier layer to eliminate inhibitors and implementing active factor regeneration and other technical means, improves the organic matter conversion efficiency (increased by more than 30%) and the system stable running time, solves technical problems such as insufficient concentration, unbalanced components and poor stability in traditional carbon source preparation, is suitable for the denitrification and dephosphorization process of a large-scale sewage treatment plant, and can increase the total nitrogen removal rate of the sewage treatment system by 15-25% and increase the denitrification rate by 30-40%.

Description

Technical Field

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

[0002] In the field of wastewater biological treatment, the addition of external carbon sources is a key factor in improving nitrogen and phosphorus removal efficiency, especially for wastewater with low carbon-to-nitrogen ratios. Traditional external carbon sources, such as methanol and sodium acetate, suffer from high prices, limited sources, and poor biological adaptability, which restricts their large-scale application. In recent years, the preparation of composite biological carbon sources from organic waste as alternatives has attracted widespread attention due to its advantages in both resource utilization and economic efficiency.

[0003] Currently, the preparation of composite biocarbon sources mainly employs solid-state fermentation or liquid-state fermentation processes. Solid-state fermentation offers advantages such as high substrate concentration and low water consumption, but suffers from poor mass transfer conditions and uneven fermentation conversion. Liquid-state fermentation offers advantages such as uniform reaction and ease of control, but results in low product concentration and high energy consumption. Each process has its advantages and disadvantages, and neither can meet the demands for efficient preparation when used alone. Furthermore, conventional fermentation processes face the following technical challenges: first, the microbial community structure is simple and its functions are limited, leading to insufficient organic matter conversion and an unbalanced carbon source composition; second, the microbial community structure is unstable during continuous operation, causing a gradual decrease in system acid production efficiency; third, inhibitory metabolites accumulate during fermentation broth reflux, affecting the long-term stable operation of the system; and fourth, the material recycling rate is low, resulting in low resource utilization efficiency.

[0004] Therefore, there is an urgent need to develop a composite biocarbon source preparation method that combines the advantages of solid-state and liquid-state fermentation, constructs an efficient and stable microbial metabolic network, and solves key obstacles in the long-term operation of fermentation systems. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing a highly efficient composite biocarbon source and its application.

[0006] A method for preparing a highly efficient composite biocarbon source includes the following steps: Step 1: Physically crush the organic waste to a particle size of no more than 5mm, adjust the moisture content to 60-70%, pH value to 6.5-7.5, carbon-nitrogen ratio to 20-30:1, and carry out solid-state fermentation for 24-48 hours; Step 2: Transfer the solid fermentation product to a liquid fermentation reactor, add water to dilute to a solid content of 8-12%, and carry out liquid fermentation for 72-96 hours; Step 3: Inoculate primary degrading bacteria during the solid-state fermentation stage, inoculate intermediate transforming bacteria during the liquid-state fermentation transition stage, and inoculate terminal functional bacteria after 72 hours of liquid-state fermentation to construct a tiered relay system of microbial communities; Step 4: Set up a porous carrier layer between solid-state fermentation and liquid-state fermentation, and inoculate the carrier with detoxification bacteria; Step 5: After 48 hours of liquid fermentation, a portion of the fermentation broth is refluxed to the solid-state fermentation stage. The initial reflux ratio is 20% of the total volume of the fermentation broth, and is gradually increased to 50-60% as the system stabilizes. Step 6: Remove solid residue by centrifugation to obtain composite biocarbon source.

[0007] Preferred method: In step 1, air is introduced during solid-state fermentation at a rate of 0.05-0.1 vvm, and the temperature is controlled within the range of 30-35℃.

[0008] Preferred method: In step 2, the liquid fermentation temperature is controlled at 33-38℃, the pH value is 5.5-6.5, the dissolved oxygen concentration is maintained at 1-2 mg / L, intermittent stirring is used, stirring for 5-10 minutes per hour, the speed is 60-80 rpm, and the aeration rate is 0.2-0.3 vvm.

[0009] Preferred method: In step 3, the primary degrading bacteria mainly include Bacillus and Clostridium, with an inoculation amount of 1-3% of the material mass; the intermediate transforming bacteria mainly include Lactobacillus and Propionibacterium, with an inoculation amount of 2-5% of the fermentation liquid volume; and the terminal functional bacteria include Clostridium and Leuconostoc, with an inoculation amount of 1-3% of the fermentation liquid volume.

[0010] Preferred: It also includes a microbial community stabilization step: adding selective growth factors every 7-10 days, including cellobiose for primary degrading bacteria at an addition amount of 0.01-0.05%; glutamic acid and arginine for intermediate transforming bacteria at an addition amount of 0.02-0.1%; and trace elements such as manganese and molybdenum for terminal functional bacteria at an addition amount of 0.001-0.005%.

[0011] Preferred: It also includes biological rhythm regulation steps: setting a 12-hour / 12-hour light-dark cycle with a light intensity of 100-200 lux; adding a mixed amino acid solution every 24 hours, with the amount added being 0.1-0.5% of the fermentation broth volume; and partially replacing 10-15% of the fermentation broth every 48 hours.

[0012] Preferably, in step 4, the porous carrier is activated carbon, volcanic rock or zeolite, and the filling height is 10-15% of the height of the liquid fermentation reactor; the detoxification bacteria include Pseudomonas aeruginosa, white rot fungi and Streptomyces, and the inoculum amount is 5-10% of the carrier mass.

[0013] Preferred: It also includes a metabolic regulation step: adding 0.02-0.05% phenylalanine, 0.01-0.03% tyrosine and 0.01-0.02% tryptophan to the fermentation system once every 48 hours.

[0014] Preferred: It also includes an inhibitor monitoring and control step: every 72 hours, the concentration of inhibitors such as total phenol, furfural, and hydroxymethylfurfural in the system is detected; when the inhibitor concentration exceeds the set threshold, the amount of detoxifying bacteria inoculated is increased, the reflux ratio is reduced, and the amount of metabolic precursor substances added is increased.

[0015] Preferred: It also includes a biomass enhancement step: inoculating polysaccharide-producing actinomycetes (0.5-1%), pigment-producing yeast (0.3-0.8%), and vitamin-producing lactic acid bacteria (1-2%) during the liquid fermentation stage; adding tryptophan (0.01-0.03%), methionine (0.01-0.02%), and niacin (0.005-0.01%) as precursors of active factors; and providing 30-60 minutes of light stimulation every 48 hours, alternating between blue light with a wavelength of 450-470 nm and red light with a wavelength of 620-660 nm, with a light intensity of 100-200 μmol / m² / s.

[0016] An application of a highly efficient composite biocarbon source prepared by the above method is shown in wastewater treatment.

[0017] The beneficial effects of this invention are as follows: The performance effects of the product prepared by the method of this invention are as follows: Increased product concentration: The COD concentration of the prepared composite bio-carbon source reached over 50,000 mg / L, which is more than 50% higher than that of single-phase fermentation, solving the problem of low product concentration in traditional fermentation. Balanced carbon source composition: The short-chain fatty acid composition ratio is optimized to approximately 3:2:1 for acetic acid:propionic acid:butyric acid, which is suitable for the metabolic needs of different functional microorganisms and solves the problem of single carbon source composition in traditional methods. Enhanced bioactivity: The product contains active substances such as extracellular polysaccharides and growth factors, which promote the rapid growth and activity recovery of functional microorganisms in the wastewater treatment system and improve the bioavailability of carbon sources. Improved application effect: Using this composite biological carbon source can increase the total nitrogen removal rate of the wastewater treatment system by 15-25% and the denitrification rate by 30-40%. It is suitable for biological denitrification processes under low temperature conditions (10-15℃), solving the problem of poor performance of traditional carbon sources under low temperature conditions.

[0018] Method efficacy: Improved organic matter conversion efficiency: The solid-liquid two-phase fermentation process and the microbial community cascade relay system improve the organic matter conversion efficiency by more than 30%, thereby increasing resource utilization. Enhanced system stability: The system's stable operating time has been extended from 60 days to over 120 days, solving the problem of poor long-term operational stability in traditional fermentation systems; Improved resource recycling rate: The fermentation broth reflux ratio increased from 20-30% to 50-60%, which improved the material recycling rate and reduced raw material consumption; Reduced operating costs: The frequency of adding exogenous active substances has been reduced from once every 3-5 days to once every 15-20 days, which has reduced production costs and improved economic efficiency.

[0019] Effects of technological progress: We developed microbial community stabilization and biological rhythm regulation technologies, which solved the problem of long-term stable operation of microbial communities and enabled the directed culture and stable maintenance of functional microbial communities. By employing porous carrier layers and metabolic regulation technology, the problem of inhibitor accumulation in reflux fermentation was solved, breaking through the technical bottleneck of traditional reflux fermentation. A pathway for the regeneration of active factors was established, enabling the self-sustaining and recycling of active substances and innovating the supply mode of bioactive substances.

[0020] Application value and effects: It has realized the resource utilization of organic wastes such as agricultural straw and food processing by-products, and has significant environmental benefits; The prepared composite biocarbon source is suitable for various wastewater treatment processes, including urban sewage, industrial wastewater, and aquaculture wastewater, and has a wide range of applications. It is suitable for large-scale wastewater treatment plants that require an external carbon source, reducing treatment costs and improving treatment efficiency, thus providing good economic and social benefits.

[0021] This invention solves key technical problems in the preparation of traditional bio-carbon sources through system optimization, forming a complete and efficient composite bio-carbon source preparation technology system with technical advantages and broad application prospects. Attached Figure Description

[0022] Figure 1 These are the changes in COD concentration of the product during the fermentation process in three sets of experiments of this invention; Figure 2 This is the trend of furfural and hydroxymethylfurfural concentration changes in this invention; Figure 3 This refers to the changes in acid production efficiency (short-chain fatty acid generation rate) during the operation of the three sets of experiments of this invention. Detailed Implementation

[0023] 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.

[0024] Example 1 This embodiment proposes a method for preparing a highly efficient composite biocarbon source, comprising the following steps: Step 1: Physically crush the organic waste to a particle size of no more than 5mm, adjust the moisture content to 60%, pH value to 6.5, carbon-nitrogen ratio to 20:1, and carry out solid-state fermentation for 24 hours; Air is introduced during solid-state fermentation at a rate of 0.05 vvm, and the temperature is controlled within the range of 30℃.

[0025] Step 2: Transfer the solid fermentation product to a liquid fermentation reactor, add water to dilute to a solid content of 8%, and carry out liquid fermentation for 72 hours; Liquid fermentation was controlled at a temperature of 33℃, a pH of 5.5, and a dissolved oxygen concentration of 1 mg / L. Intermittent stirring was used, with stirring for 5 minutes every hour at a speed of 60 rpm and an aeration rate of 0.2 vvm.

[0026] Step 3: Inoculate primary degrading bacteria during the solid-state fermentation stage, inoculate intermediate transforming bacteria during the liquid-state fermentation transition stage, and inoculate terminal functional bacteria after 72 hours of liquid-state fermentation to construct a tiered relay system of microbial communities; Primary degrading bacteria mainly include Bacillus and Clostridium, with an inoculum size of 1% of the material mass; intermediate transforming bacteria mainly include Lactobacillus and Propionibacterium, with an inoculum size of 2% of the fermentation broth volume; terminal functional bacteria include Clostridium and Leuconostoc, with an inoculum size of 1% of the fermentation broth volume.

[0027] Step 4: Set up a porous carrier layer between solid-state fermentation and liquid-state fermentation, and inoculate the carrier with detoxification bacteria; The porous carrier is activated carbon, and the filling height is 10% of the height of the liquid fermentation reactor; the detoxification bacteria include Pseudomonas aeruginosa, white rot fungi and Streptomyces, and the inoculum amount is 5% of the carrier mass.

[0028] Step 5: After 48 hours of liquid fermentation, a portion of the fermentation broth is refluxed to the solid-state fermentation stage. The initial reflux ratio is 20% of the total volume of the fermentation broth, which is gradually increased to 50% as the system stabilizes. Step 6: Remove solid residue by centrifugation to obtain composite biocarbon source.

[0029] It also includes a microbial stabilization step: selective growth factors are added every 7 days, including cellobiose for primary degrading bacteria at an addition amount of 0.01%; glutamic acid and arginine for intermediate transforming bacteria at an addition amount of 0.02%; and trace elements such as manganese and molybdenum for terminal functional bacteria at an addition amount of 0.001%.

[0030] It also includes biological rhythm regulation steps: setting a 12-hour / 12-hour light-dark cycle with a light intensity of 100 lux; adding a mixed amino acid solution every 24 hours at a rate of 0.1% of the fermentation broth volume; and partially replacing 10% of the fermentation broth every 48 hours.

[0031] It also includes a metabolic regulation step: adding 0.02% phenylalanine, 0.01% tyrosine and 0.01% tryptophan to the fermentation system once every 48 hours.

[0032] It also includes inhibitor monitoring and control steps: every 72 hours, the concentration of inhibitors such as total phenol, furfural, and hydroxymethylfurfural in the system is detected; when the inhibitor concentration exceeds the set threshold, the amount of detoxifying bacteria inoculated is increased, the reflux ratio is reduced, and the amount of metabolic precursor substances added is increased.

[0033] It also includes a biomass enhancement step: inoculating the liquid fermentation stage with 0.5-1% polysaccharide-producing actinomycetes, 0.3-0.8% pigment-producing yeasts, and 1-2% vitamin-producing lactic acid bacteria; adding 0.01-0.03% tryptophan, 0.01-0.02% methionine, and 0.005-0.01% niacin as precursors for active factors; and providing 30-60 minutes of light stimulation every 48 hours, alternating between blue light with a wavelength of 450-470nm and red light with a wavelength of 620-660nm, with a light intensity of 100-200μmol / m² / s.

[0034] Example 2 This embodiment proposes a method for preparing a highly efficient composite biocarbon source, comprising the following steps: Step 1: Physically crush the organic waste to a particle size of no more than 5mm, adjust the moisture content to 65%, pH value to 7.0, carbon-nitrogen ratio to 25:1, and carry out solid-state fermentation for 36 hours; Solid-state fermentation involves introducing air at a rate of 0.08 vvm, while maintaining the temperature within the range of 32℃.

[0035] Step 2: Transfer the solid fermentation product to a liquid fermentation reactor, add water to dilute it to a solid content of 10%, and carry out liquid fermentation for 74 hours; Liquid fermentation was controlled at a temperature of 35℃, a pH of 6.0, and a dissolved oxygen concentration of 1.5 mg / L. Intermittent stirring was used, with stirring for 8 minutes per hour at a speed of 70 rpm and an aeration rate of 0.25 vvm.

[0036] Step 3: Inoculate primary degrading bacteria during the solid-state fermentation stage, inoculate intermediate transforming bacteria during the liquid-state fermentation transition stage, and inoculate terminal functional bacteria after 72 hours of liquid-state fermentation to construct a tiered relay system of microbial communities; Primary degrading bacteria mainly include Bacillus and Clostridium, with an inoculum size of 2% of the material mass; intermediate transforming bacteria mainly include Lactobacillus and Propionibacterium, with an inoculum size of 4% of the fermentation broth volume; terminal functional bacteria include Clostridium and Leuconostoc, with an inoculum size of 2% of the fermentation broth volume.

[0037] Step 4: Set up a porous carrier layer between solid-state fermentation and liquid-state fermentation, and inoculate the carrier with detoxification bacteria; In step 4, the porous carrier is zeolite, and the filling height is 12% of the height of the liquid fermentation reactor; the detoxification bacteria include Pseudomonas aeruginosa, white rot fungi and Streptomyces, and the inoculum amount is 8% of the carrier mass.

[0038] Step 5: After 48 hours of liquid fermentation, a portion of the fermentation broth is refluxed to the solid-state fermentation stage. The initial reflux ratio is 20% of the total volume of the fermentation broth, which is gradually increased to 55% as the system stabilizes. Step 6: Remove solid residue by centrifugation to obtain composite biocarbon source.

[0039] It also includes a microbial stabilization step: selective growth factors are added every 8 days, including cellobiose for primary degrading bacteria at a dosage of 0.03%; glutamic acid and arginine for intermediate transforming bacteria at a dosage of 0.06%; and trace elements such as manganese and molybdenum for terminal functional bacteria at a dosage of 0.003%.

[0040] It also includes biological rhythm regulation steps: setting a 12-hour / 12-hour light-dark cycle with a light intensity of 150 lux; adding a mixed amino acid solution every 24 hours at a rate of 0.3% of the fermentation broth volume; and partially replacing 12% of the fermentation broth every 48 hours.

[0041] It also includes a metabolic regulation step: adding 0.03% phenylalanine, 0.02% tyrosine and 0.015% tryptophan to the fermentation system once every 48 hours.

[0042] It also includes inhibitor monitoring and control steps: every 72 hours, the concentration of inhibitors such as total phenol, furfural, and hydroxymethylfurfural in the system is detected; when the inhibitor concentration exceeds the set threshold, the amount of detoxifying bacteria inoculated is increased, the reflux ratio is reduced, and the amount of metabolic precursor substances added is increased.

[0043] It also includes a biomass enhancement step: during the liquid fermentation stage, 0.8% of polysaccharide-producing actinomycetes, 0.5% of pigment-producing yeast, and 1.5% of vitamin-producing lactic acid bacteria are inoculated; 0.02% tryptophan, 0.015% methionine, and 0.008% niacin are added as precursors for active factors; and 45 minutes of light stimulation is applied every 48 hours, alternating between blue light with a wavelength of 460nm and red light with a wavelength of 640nm, with a light intensity of 150μmol / m² / s.

[0044] Example 3 This embodiment proposes a method for preparing a highly efficient composite biocarbon source, comprising the following steps: Step 1: Physically crush the organic waste to a particle size of no more than 5mm, adjust the moisture content to 70%, pH value to 7.5, carbon-nitrogen ratio to 30:1, and carry out solid-state fermentation for 48 hours; Solid-state fermentation involves introducing air at a rate of 0.1 vvm, while maintaining the temperature within the range of 35℃.

[0045] Step 2: Transfer the solid fermentation product to a liquid fermentation reactor, add water to dilute it to a solid content of 12%, and carry out liquid fermentation for 96 hours; Liquid fermentation was controlled at a temperature of 38℃, a pH of 6.5, and a dissolved oxygen concentration of 2 mg / L. Intermittent stirring was used, with stirring for 10 minutes every hour at a speed of 80 rpm and an aeration rate of 0.3 vvm.

[0046] Step 3: Inoculate primary degrading bacteria during the solid-state fermentation stage, inoculate intermediate transforming bacteria during the liquid-state fermentation transition stage, and inoculate terminal functional bacteria after 72 hours of liquid-state fermentation to construct a tiered relay system of microbial communities; Primary degrading bacteria mainly include Bacillus and Clostridium, with an inoculum size of 3% of the material mass; intermediate transforming bacteria mainly include Lactobacillus and Propionibacterium, with an inoculum size of 5% of the fermentation broth volume; terminal functional bacteria include Clostridium and Leuconostoc, with an inoculum size of 3% of the fermentation broth volume.

[0047] Step 4: Set up a porous carrier layer between solid-state fermentation and liquid-state fermentation, and inoculate the carrier with detoxification bacteria; In step 4, the porous carrier is activated carbon or volcanic rock, and the filling height is 15% of the height of the liquid fermentation reactor; the detoxification bacteria include Pseudomonas aeruginosa, white rot fungi and Streptomyces, and the inoculum amount is 10% of the carrier mass.

[0048] Step 5: After 48 hours of liquid fermentation, a portion of the fermentation broth is refluxed to the solid-state fermentation stage. The initial reflux ratio is 20% of the total volume of the fermentation broth, which is gradually increased to 60% as the system stabilizes. Step 6: Remove solid residue by centrifugation to obtain composite biocarbon source.

[0049] It also includes a microbial stabilization step: adding selective growth factors every 10 days, including cellobiose for primary degrading bacteria at a dosage of 0.05%; glutamic acid and arginine for intermediate transforming bacteria at a dosage of 0.1%; and trace elements such as manganese and molybdenum for terminal functional bacteria at a dosage of 0.005%.

[0050] It also includes biological rhythm regulation steps: setting a 12-hour / 12-hour light-dark cycle with a light intensity of 200 lux; adding a mixed amino acid solution every 24 hours at a rate of 0.5% of the fermentation broth volume; and partially replacing 15% of the fermentation broth every 48 hours.

[0051] It also includes a metabolic regulation step: adding 0.05% phenylalanine, 0.03% tyrosine and 0.02% tryptophan to the fermentation system once every 48 hours.

[0052] It also includes inhibitor monitoring and control steps: every 72 hours, the concentration of inhibitors such as total phenol, furfural, and hydroxymethylfurfural in the system is detected; when the inhibitor concentration exceeds the set threshold, the amount of detoxifying bacteria inoculated is increased, the reflux ratio is reduced, and the amount of metabolic precursor substances added is increased.

[0053] It also includes a biomass enhancement step: inoculating the liquid fermentation stage with 0.5-1% polysaccharide-producing actinomycetes, 0.3-0.8% pigment-producing yeasts, and 1-2% vitamin-producing lactic acid bacteria; adding 0.01-0.03% tryptophan, 0.01-0.02% methionine, and 0.005-0.01% niacin as precursors for active factors; and providing 30-60 minutes of light stimulation every 48 hours, alternating between blue light with a wavelength of 450-470nm and red light with a wavelength of 620-660nm, with a light intensity of 100-200μmol / m² / s.

[0054] Example 4 This embodiment presents an application of a highly efficient composite biocarbon source prepared by the method of Example 2, which is used in wastewater treatment.

[0055] Example 5 This embodiment proposes a method for preparing a highly efficient composite biocarbon source, comprising the following steps: 1. Basic Solid-Liquid Two-Phase Fermentation Process The basic solid-liquid two-phase fermentation process of the present invention includes the following steps: 1.1 Raw material pretreatment: Agricultural straw, food processing by-products, and other organic waste are selected as raw materials, physically crushed to a particle size of no more than 5 mm, and the moisture content is adjusted to 60-70%, the pH value to 6.5-7.5, and the carbon-nitrogen ratio to 20-30:1. These parameter ranges have been experimentally verified to create suitable conditions for solid-state fermentation, promoting microbial growth and metabolic activities.

[0056] 1.2 Solid-state fermentation stage: The pretreated material is placed in a solid-state fermentation reactor, and air is introduced (0.05-0.1 vvm) to maintain a microaerobic environment. The temperature is controlled within the range of 30-35℃, and the fermentation time is 24-48 hours. During this stage, the material is solid or semi-solid, and microorganisms grow on the surface and in the internal pores of the material, producing hydrolytic enzymes and forming a biofilm. The controlled microaerobic conditions promote the production of hydrolytic enzymes and the colonization of primary degrading bacteria, providing the enzyme system and active bacterial community basis for subsequent liquid fermentation.

[0057] 1.3 Liquid Fermentation Transition: After solid-state fermentation, the fermentation product is transferred to a liquid fermentation reactor, and water is added to dilute it to a solid content of 8-12%, forming a slurry. The stirring speed is controlled at 20-40 rpm to avoid high shear force damaging the microbial growth environment. This process achieves the transition from solid to liquid state, retains the enzyme and microbial activity produced by solid-state fermentation, and improves mass transfer efficiency.

[0058] 1.4 Liquid Fermentation Stage: In the liquid fermentation reactor, the temperature is controlled at 33-38℃, pH at 5.5-6.5, dissolved oxygen concentration at 1-2 mg / L, and fermentation time at 72-96 hours. Intermittent stirring (5-10 minutes per hour, 60-80 rpm) and aeration (0.2-0.3 vvm) are employed to improve mass transfer efficiency and promote the production and accumulation of soluble organic matter. By optimizing stirring and aeration parameters, the generation of soluble organic matter is promoted while maintaining microbial activity, achieving efficient conversion of organic matter.

[0059] 1.5 Collection and Treatment of Fermentation Products: After liquid fermentation, the fermentation broth is centrifuged (3000-5000 r / min, 10-15 minutes) to remove solid residue, obtaining a liquid composite biological carbon source containing high concentrations of organic matter (COD≥50,000 mg / L). Depending on application requirements, the product can be concentrated or diluted to meet the carbon source replenishment needs of different wastewater treatment processes.

[0060] Through the above-mentioned solid-liquid two-phase fermentation process, this invention realizes the conversion of organic waste into a high-concentration composite biocarbon source. Compared with single-phase fermentation, the product concentration is increased by more than 50%, and the composition is more comprehensive and balanced, solving the technical problems of low product concentration and single composition in traditional single fermentation processes.

[0061] 2. Microbial community tiered relay system The microbial community cascade relay system of this invention constructs a functionally complementary microbial metabolic network, thereby improving the efficiency of organic matter conversion. The specific steps are as follows: 2.1 Isolation and Cultivation of Functional Microbial Communities: Three types of functional microbial communities were isolated from environments such as sewage treatment plants, biogas digesters, and composting sites: - Primary Degrading Bacteria: mainly including Bacillus and Clostridium species, which can decompose complex organic matter such as cellulose and hemicellulose; - Intermediate Transforming Bacteria: mainly including Lactobacillus and Propionibacterium species, which can convert monosaccharides and oligosaccharides into short-chain fatty acids; - Terminal Functional Bacteria: including Clostridium and Leuconostoc species, which can produce functional products such as butyric acid and extracellular polysaccharides.

[0062] The isolated strains were screened and prepared into fermentation spawns containing three functional bacterial groups (cell concentration ≥10). 9 (CFU / mL). This step constructed three functionally complementary bacterial communities, which differs from conventional mixed-strain fermentation and provides a bacterial foundation for subsequent cascade fermentation systems.

[0063] 2.2 Construction of the tiered relay system: Based on the spatial separation of the solid-liquid two-phase fermentation process, the microbial community is inoculated according to the metabolic sequence: - Before the start of the solid-state fermentation stage, primary degrading bacteria are inoculated into the pretreated material at a rate of 1-3% of the material mass for the decomposition of complex organic matter; - In the liquid fermentation transition stage, intermediate transforming bacteria are inoculated into the liquid fermentation reactor at a rate of 2-5% of the fermentation liquid volume for the conversion of simple organic matter into short-chain fatty acids; - After 72 hours of liquid fermentation, terminal functional bacteria are inoculated at a rate of 1-3% of the fermentation liquid volume for the generation of functional products such as butyric acid and extracellular polysaccharides.

[0064] This relay inoculation strategy enables each microbial community to function under suitable environmental conditions and metabolic stages, forming a synergistic effect and achieving the cascade transformation and efficient utilization of organic matter.

[0065] 2.3 Microbial Community Stabilization Technology: To maintain the stability of the microbial community structure, the following methods are adopted: - Selective growth factors are added every 7-10 days, including: cellobiose for primary degrading bacteria (addition amount 0.01-0.05%); glutamic acid and arginine for intermediate transforming bacteria (addition amount 0.02-0.1%); and trace elements such as manganese and molybdenum for terminal functional bacteria (addition amount 0.001-0.005%). - These growth factors provide favorable growth conditions for the target microbial community, inhibit the excessive growth of non-target microbial communities, maintain the stability of the microbial community, and solve the problem of functional decline caused by microbial succession during continuous fermentation.

[0066] 2.4 Biological rhythm regulation technology: Microbial metabolic activities are regulated through the following periodic operations: - Set a 12-hour / 12-hour light-dark cycle (light intensity 100-200 lux); - Add a mixed amino acid solution every 24 hours (the amount added is 0.1-0.5% of the fermentation broth volume); - Partially replace 10-15% of the fermentation broth every 48 hours.

[0067] These periodic operations cause the growth and metabolic activities of microorganisms to exhibit regular changes, avoiding community structure imbalance, extending the stable operation time of the system, and solving the problem of poor long-term operational stability of traditional fermentation systems.

[0068] Through the aforementioned microbial community tiered relay system, this invention improves the organic matter conversion efficiency by more than 30%, and the short-chain fatty acid composition ratio in the composite biological carbon source is approximately acetic acid:propionic acid:butyric acid 3:2:1. The stable operation time of the system is extended from 60 days to more than 120 days, solving the problem of decreased acid production efficiency caused by unstable microbial community structure in traditional fermentation systems.

[0069] 3. Fermentation broth reflux and biological detoxification system This invention develops a fermentation broth reflux and biological detoxification system, which improves the system's material recycling rate. The specific steps are as follows: 3.1 Establishment of Fermentation Broth Reflux Path: Establish a fermentation broth reflux path in the solid-liquid two-phase fermentation system: - After 48 hours of liquid fermentation, reflux is started, with an initial reflux ratio of 20% of the total fermentation broth volume; - As the system stabilizes, gradually increase the reflux ratio to 50-60%; - Reflux is performed once every 24 hours. Before reflux, the fermentation broth is filtered to remove suspended solids.

[0070] This reflux pathway enables the recycling of enzymes, intermediate metabolites, and microorganisms, improving material conversion efficiency and reducing raw material consumption. However, it also brings about the problem of inhibitor accumulation, which needs to be solved through the following technologies.

[0071] 3.2 Construction of the biological detoxification layer: A porous carrier layer is set between solid-state fermentation and liquid-state fermentation: - Porous carriers such as activated carbon, volcanic rock, and zeolite are used as microbial attachment substrates, with a filling height of 10-15% of the height of the liquid fermentation reactor; - Detoxification bacteria are inoculated on the carrier, including Pseudomonas aeruginosa (degrading phenolic compounds), white-rot fungi (converting furan derivatives), and Streptomyces (decomposing organic acids); - The inoculation amount is 5-10% of the carrier mass. The carrier is sterilized and pretreated before inoculation to enhance the microbial attachment ability.

[0072] This porous carrier layer transforms phenolic compounds and furan derivatives in the reflux fermentation broth into low-toxicity or non-toxic metabolites through microbial metabolism, reducing the impact of inhibitors on the system and solving the problem of system inactivation caused by the accumulation of inhibitors in traditional reflux fermentation.

[0073] 3.3 Metabolic Regulation Strategy: Regulating microbial metabolic pathways by adding metabolic precursors: - Add amino acids such as phenylalanine (0.02-0.05%), tyrosine (0.01-0.03%), and tryptophan (0.01-0.02%) to the fermentation system; - These amino acids activate microbial metabolic pathways, redirecting intermediate metabolites that produce inhibitors to the aromatic amino acid synthesis pathway; - Add the amino acids every 48 hours in the liquid fermentation reactor.

[0074] This metabolic regulation method reduces the production of inhibitors by adjusting the direction of microbial metabolism, thus ensuring an increase in the reflux ratio and serving as a supplementary measure to address the problem of inhibitors in reflux fermentation.

[0075] 3.4 Inhibitor Monitoring and Control: Establish an inhibitor monitoring and control method: - Monitor the concentration of major inhibitors (total phenols, furfural, hydroxymethylfurfural, etc.) in the system every 72 hours; - When the inhibitor concentration exceeds the set threshold (total phenols > 500 mg / L, furfural > 100 mg / L, hydroxymethylfurfural > 150 mg / L), increase the inoculum size of detoxifying bacteria, decrease the reflux ratio, and increase the amount of metabolic precursors added; - After the inhibitor concentration drops to a safe range, restore the normal operating parameters.

[0076] This monitoring and control method enables real-time control of the system's inhibitor levels, ensuring the effective operation of the biological detoxification system and guaranteeing its long-term stability.

[0077] Through the above-mentioned fermentation broth reflux and biological detoxification system, the present invention increases the reflux ratio from 20-30% to 50-60%, significantly improving the material recycling rate of the system, reducing resource consumption, and solving the technical problem of system instability caused by the accumulation of inhibitors in traditional reflux fermentation.

[0078] 4. Biomass Enhancement Strategies The biomass enhancement strategy of this invention improves the system's acid production efficiency and enhances the bioactivity of the composite bio-carbon source. The specific steps are as follows: 4.1 Preparation of Bioactive Substances: Three types of bioactive substances were screened and prepared: - Microalgae Extracts: Chlorella, Spirulina, etc., were extracted using ultrasound-assisted extraction (power 300-500W, frequency 20-40kHz, extraction time 15-30 minutes) to obtain extracts containing polysaccharides, pigments, and vitamins; - Plant Secondary Metabolites: Scutellaria baicalensis, Lonicera japonica, etc., were extracted using a water-ethanol gradient extraction (ethanol concentration 30-70%, extraction temperature 40-60℃) to obtain extracts containing flavonoids, terpenes, and other compounds; - Microbial Metabolites: Extracellular polysaccharides, cytokines, and other active substances were extracted from the supernatant of cultures of Lactobacillus, Bifidobacterium, etc.

[0079] These substances are purified, concentrated, and stabilized to produce an activity enhancer (total active substance content ≥5%). This step provides raw materials for subsequent biomass enhancement, but in traditional methods, these active substances need to be added exogenously frequently, which is costly and has unstable effects. This invention solves this problem through the following steps.

[0080] 4.2 Auxiliary Microbial Introduction Technology: Auxiliary microorganisms capable of producing target active substances are introduced into the fermentation system: - Inoculate polysaccharide-producing actinomycetes (Streptomyces, Nocardia, inoculation amount 0.5-1% of fermentation broth volume), pigment-producing yeasts (Rhodotorula, inoculation amount 0.3-0.8% of fermentation broth volume), and vitamin-producing lactic acid bacteria (Lactobacillus plantarum, inoculation amount 1-2% of fermentation broth volume) during the liquid fermentation stage; - Provide carbon sources (lactose, maltose, etc., addition amount 0.1-0.3%) and nitrogen sources (peptone, yeast extract, etc., addition amount 0.05-0.2%) for the auxiliary microorganisms; - Regulate fermentation conditions (pH fluctuating between 5.0-7.0, dissolved oxygen concentration varying between 0.5-2 mg / L) to promote the symbiosis between auxiliary microorganisms and functional flora.

[0081] This auxiliary microbial introduction technology enables the continuous production of active substances, reduces the need for exogenous addition, and solves the problem of unstable supply of active substances in traditional methods.

[0082] 4.3 Establishment of Active Factor Regeneration Pathway: The active factor regeneration pathway is established through the following measures: - Adding precursor substances, including amino acids and vitamin precursors such as tryptophan (0.01-0.03%), methionine (0.01-0.02%), and niacin (0.005-0.01%); - Providing 30-60 minutes of light stimulation every 48 hours (alternating between blue light with a wavelength of 450-470 nm and red light with a wavelength of 620-660 nm, with a light intensity of 100-200 μmol / m² / s) to promote the synthesis of photosynthetic substances; - Supplementing with trace elements (zinc, iron, selenium, etc., with a total addition of 0.001-0.005%) to activate the activity of synthases; - Extracting a portion of the fermentation broth (approximately 10%) from the system every 72 hours, concentrating it through ultrafiltration, and then adding it back to the fermentation system to achieve the enrichment and recycling of active factors.

[0083] This active factor regeneration pathway enables the continuous generation and recycling of active substances within the system, reduces the frequency and amount of exogenous addition, and improves the system's self-sustaining ability, which is an important innovation of this invention.

[0084] 4.4 Monitoring and Regulation of Biomass Enhancement Effect: The biomass enhancement effect is monitored and regulated in the following ways: - The content of key active substances in the system (polysaccharides, flavonoids, B vitamins, etc.) and the bioactivity of the fermentation broth are tested every 7 days (evaluated by the growth-promoting effect of indicator microorganisms); - Based on the test results, the inoculum size of auxiliary microorganisms, the amount of precursor substances added, and the microenvironment parameters are adjusted; - When the biomass enhancement effect decreases, exogenous active substances are added (0.5-1% of the fermentation broth volume), and the system conditions are adjusted to restore regeneration capacity.

[0085] Experimental verification To verify the technical effects of this invention, we selected two of the most innovative technical effects for experimental verification: 1) the effect of the microbial community cascade relay system on improving the efficiency of organic matter conversion; and 2) the influence of porous carrier layer and metabolic regulation technology on system stability. The following are the detailed steps and results of the relevant experiments.

[0086] Experiment 1: The Effect of Microbial Community Cascade Relay System on Organic Matter Conversion Efficiency 1. Experimental Objective To verify the advantages of the microbial community cascade system over traditional mixed microbial fermentation in terms of organic matter conversion efficiency, short-chain fatty acid composition, and product concentration.

[0087] 2. Materials and Methods 2.1 Experimental Design Three parallel experiments were set up: - Experimental group A: The microbial community tiered relay system of the present invention was used (operated according to steps 2.1-2.4 in Implementation Method 1) - Control group B: The traditional mixed microbial community was used for one-time inoculation - Control group C: A single microbial community was used (only intermediate transformation bacteria were used).

[0088] 2.2 Raw material preparation Corn stalks were selected as the main raw material and pretreated according to step 1.1 in Implementation Method 1.

[0089] 2.3 Experimental Setup A 5L laboratory fermenter is used, equipped with temperature, pH, and dissolved oxygen control systems. Solid-state fermentation uses a dedicated solid-state fermentation device equipped with a ventilation system.

[0090] 2.4 Experimental Procedure Perform the basic solid-liquid two-phase fermentation process according to steps 1.1-1.5 in Implementation Method 1.

[0091] For experimental group A, the bacterial colony was inoculated according to step 2.2 in Implementation Method 1: During the solid-state fermentation stage, primary degrading bacteria (a mixed culture of Bacillus and Clostridium) are inoculated at a rate of 2% of the material mass. During the transition stage of liquid fermentation, intermediate-stage transformation bacteria (a mixed culture of Lactobacillus and Propionibacterium) are inoculated at a rate of 3% of the fermentation broth volume. After 72 hours of liquid fermentation, terminal functional bacteria (a mixed culture of Clostridium and Leuconostoc) were inoculated at a volume of 2% of the fermentation liquid. For control group B, a mixed bacterial solution of the above three types of bacteria was inoculated once during the solid-state fermentation stage, with the total inoculation amount being the same as that of experimental group A.

[0092] For control group C, intermediate transformant bacteria were inoculated only during the liquid fermentation transition stage, with an inoculation amount of 7% of the fermentation liquid volume.

[0093] All three groups of experiments were fermented according to the process parameters in Implementation Method 1.

[0094] Samples are taken every 24 hours to analyze organic matter conversion rate, short-chain fatty acid composition, and COD concentration.

[0095] Final product analysis was conducted after fermentation was completed (96 hours).

[0096] 2.5 Analytical Methods Organic matter conversion rate: Calculated by measuring the change in organic matter content before and after fermentation, and expressed as the VS (volatile solids) reduction rate.

[0097] Short-chain fatty acid composition: The contents of acetic acid, propionic acid, butyric acid, etc. were determined by gas chromatography (GC).

[0098] COD concentration: determined by the potassium dichromate method.

[0099] 3. Experimental Results 3.1 Organic matter conversion efficiency The organic matter conversion rate (VS reduction rate) of the three groups of experiments at different fermentation times is shown in the table below:

[0100] The data in the table show that the organic matter conversion rate of experimental group A, which adopted the microbial community cascade relay system, was significantly higher than that of the control group at all time points. Especially in the later stage of fermentation (96h), the organic matter conversion rate of experimental group A reached 78.6%, which was 26.2 percentage points higher than that of control group B and 37.3 percentage points higher than that of control group C. This demonstrates the significant advantage of the microbial community cascade relay system in terms of organic matter conversion efficiency.

[0101] 3.2 Short-chain fatty acid composition The short-chain fatty acid composition of the three groups of experiments after fermentation (96 h) is shown in the table below:

[0102] The results showed that experimental group A not only had a significantly higher total amount of short-chain fatty acids than the control group (about 78% higher), but also had a more balanced component ratio, with the ratio of acetic acid:propionic acid:butyric acid close to 3:2:1, which is more conducive to the needs of different functional microorganisms in the downstream wastewater treatment system.

[0103] 3.3 Changes in COD concentration of products Figure 1 Changes in COD concentration of products during fermentation in three groups of experiments.

[0104] As shown in the figure, the COD concentration of experimental group A increased at a significantly faster rate than that of the control group, reaching a final concentration of 52,000 mg / L, far exceeding the 35,000 mg / L of control group B and the 28,000 mg / L of control group C. This indicates that the microbial community cascade relay system can significantly improve the product concentration, achieving the goal of preparing a high-concentration composite biocarbon source.

[0105] 3.4 Conclusion The following conclusions can be drawn from the above experimental results: Compared with traditional mixed microbial fermentation and single-microbial fermentation, the microbial community cascade system can significantly improve the efficiency of organic matter conversion, with an improvement of more than 30%.

[0106] The composite bio-carbon source prepared using a tiered relay system has a more balanced short-chain fatty acid composition, with an acetic acid:propionic acid:butyric acid ratio close to 3:2:1, which is more beneficial for downstream applications.

[0107] The tiered relay system can achieve the preparation of high-concentration (COD≥50,000mg / L) composite biocarbon sources, with the product concentration increased by about 50% compared with traditional methods.

[0108] These results fully verify the innovation and effectiveness of the microbial community cascade relay system in this invention, and provide technical support for the preparation of efficient composite biocarbon sources.

[0109] Experiment 2: The Influence of Porous Carrier Layers and Metabolic Regulation Techniques on System Stability 1. Experimental Objective To verify the effects of porous carrier layers and metabolic regulation technology on the long-term stability of the fermentation broth reflux system, as well as its role in the accumulation of inhibitors and the improvement of the reflux ratio.

[0110] 2. Materials and Methods 2.1 Experimental Design Three long-term experimental groups (120 days) were set up: - Experimental group D: using the porous carrier layer and metabolic regulation technology of the present invention (operating according to steps 3.2 and 3.3 in Implementation Method 1) - Control group E: using only the porous carrier layer without metabolic regulation - Control group F: conventional reflux fermentation without using the porous carrier layer and metabolic regulation technology.

[0111] 2.2 Raw material preparation Corn stalks and food processing by-products (starch factory waste residue) were selected as raw materials and mixed in a 3:1 ratio. The mixture was pretreated according to step 1.1 in Implementation Method 1.

[0112] 2.3 Experimental Setup A 20L pilot-scale fermentation system was used, including a solid-state fermentation unit, a liquid-state fermenter, a porous carrier layer device, and a reflux system. The fermentation system is equipped with an automatic control device that can automatically control parameters such as temperature, pH, dissolved oxygen, agitation, and aeration.

[0113] 2.4 Experimental Procedure Establish a solid-liquid two-phase fermentation system and a microbial community cascade relay system according to steps 1.1-1.5 and 2.1-2.4 in Implementation Method 1.

[0114] For experimental group D: A porous carrier layer was set between solid-state fermentation and liquid-state fermentation, using a mixture of activated carbon and zeolite (1:1) as the carrier, with a filling height of 12% of the height of the liquid-state fermentation reactor; The carrier was inoculated with a mixture of detoxifying bacteria (Pseudomonas aeruginosa, white-rot fungi, and Streptomyces) at a concentration of 7% of the carrier mass. Add the following metabolic precursors every 48 hours: 0.03% phenylalanine, 0.02% tyrosine, and 0.015% tryptophan.

[0115] For control group E: The same porous carrier layer and detoxifying bacteria were used as in experimental group D. No metabolic precursors are added.

[0116] For control group F: No porous carrier layer or detoxifying bacteria are included; No metabolic precursors are added; All three experiments started with a reflux ratio of 20%, and the reflux ratio was gradually increased according to the system stability, reaching a maximum of 60%.

[0117] Samples are taken every 10 days to analyze the concentration of inhibitors, acid production efficiency, and microbial community structure.

[0118] Record the highest achievable reflux ratio and system stable operation time for each group of experiments.

[0119] 2.5 Analytical Methods Inhibitor analysis: Total phenols: determined by the Folin-Ciocalteu method; Furfural and hydroxymethylfurfural: determined by high performance liquid chromatography (HPLC); Acid production efficiency: The rate of short-chain fatty acid production (g / L·d) was determined. Microbial community structure: High-throughput sequencing technology was used to analyze changes in microbial community composition.

[0120] 3. Experimental Results 3.1 System stable operating time and maximum reflux ratio The system's stable operating time and maximum achievable reflux rate for the three sets of experiments are shown in the table below:

[0121] The results showed that experimental group D, which used the porous carrier layer and metabolic regulation technology, maintained stable operation during the 120-day experimental period, with a maximum reflux ratio of 60%. Control group E, which used only the porous carrier layer, maintained stable operation for 85 days, with a maximum reflux ratio of 45%. In contrast, control group F, which used conventional reflux fermentation, only maintained stable operation for 58 days, with a maximum reflux ratio of 30%. This demonstrates that the porous carrier layer and metabolic regulation technology of this invention can significantly extend the stable operation time of the system and improve the reflux ratio.

[0122] 3.2 Changes in inhibitor concentration The changes in total phenol concentration during the operation of the three experimental groups are shown in the table below:

[0123] Figure 2 Trends in the concentrations of furfural and hydroxymethylfurfural.

[0124] As can be seen from the tables and figures, the concentrations of inhibitors (total phenols, furfural, and hydroxymethylfurfural) in experimental group D remained at low levels throughout, even after 120 days of operation, and were still below the system inactivation thresholds (total phenols <500 mg / L, furfural <100 mg / L, hydroxymethylfurfural <150 mg / L). In contrast, the inhibitor concentrations in control groups E and F accumulated rapidly, ultimately leading to system inactivation. This indicates that porous carrier layers and metabolic regulation technology can effectively control the accumulation of inhibitors and prolong the stable operating time of the system.

[0125] 3.3 Changes in acid production efficiency Figure 3 The changes in acid production efficiency (rate of short-chain fatty acid production) during the operation of the three experimental groups.

[0126] As shown in the figure, the acid production efficiency of experimental group D remained at a high level during the 120-day operation period, decreasing only from the initial 8.5 g / L·d to 7.4 g / L·d, a decrease of approximately 13%. In contrast, the acid production efficiency of control group E decreased to 4.2 g / L·d after 70 days, a decrease of 50%, and the system became inactive after 90 days. The acid production efficiency of control group F decreased even more rapidly, dropping to 3.8 g / L·d after 50 days, a decrease of 54%, and the system became inactive after 70 days. This indicates that the porous carrier layer and metabolic regulation technology can effectively maintain the acid production efficiency of the system and ensure long-term stable operation.

[0127] 3.4 Conclusion The following conclusions can be drawn from the above experimental results: The combined application of porous carrier layers and metabolic regulation technology can significantly extend the stable operation time of fermentation systems, from the traditional 60 days to more than 120 days, an improvement of more than 100%.

[0128] This combination of technologies can effectively control the accumulation of inhibitors (total phenols, furfural, and hydroxymethylfurfural), keeping their concentrations within a safe range.

[0129] Through effective control of inhibitors, the system's maximum reflux ratio has been increased from the traditional 20-30% to 50-60%, improving the material recycling efficiency of reflux fermentation.

[0130] The system's acid production efficiency remained stable during long-term operation, maintaining above 87% of the initial level even after 120 days.

[0131] These results fully verify the innovation and effectiveness of the porous carrier layer and metabolic regulation technology in this invention, and provide a feasible solution to the technical problem of system instability caused by the accumulation of inhibitors in reflux fermentation.

[0132] 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 preparing a highly efficient composite biocarbon source, characterized in that, Includes the following steps: Step 1: Physically crush the organic waste to a particle size of no more than 5mm, adjust the moisture content to 60-70%, pH value to 6.5-7.5, carbon-nitrogen ratio to 20-30:1, and carry out solid-state fermentation for 24-48 hours; Step 2: Transfer the solid fermentation product to a liquid fermentation reactor, add water to dilute to a solid content of 8-12%, and carry out liquid fermentation for 72-96 hours; Step 3: Remove solid residue by centrifugation to obtain a composite biocarbon source; The above process runs continuously in a cycle of 120 days. in: Primary degrading bacteria include Bacillus and Clostridium, with an inoculum size of 1-3% of the material mass; intermediate transforming bacteria include Lactobacillus and Propionibacterium, with an inoculum size of 2-5% of the fermentation broth volume; terminal functional bacteria include Clostridium and Leuconostoc, with an inoculum size of 1-3% of the fermentation broth volume. Primary degrading bacteria were inoculated during the solid-state fermentation stage, intermediate transforming bacteria were inoculated during the liquid-state fermentation transition stage, and terminal functional bacteria were inoculated after 72 hours of liquid-state fermentation to construct a tiered relay system of microbial community. A porous carrier layer is set between solid-state fermentation and liquid-state fermentation, and detoxification bacteria are inoculated on the carrier. After 48 hours of liquid fermentation, a portion of the fermentation broth is refluxed to the solid-state fermentation stage. The initial reflux ratio is 20% of the total volume of the fermentation broth, which is gradually increased to 50-60% as the system stabilizes.

2. The method for preparing a high-efficiency composite biocarbon source according to claim 1, characterized in that, In step 1, air is introduced during solid-state fermentation at a rate of 0.05-0.1 vvm, and the temperature is controlled within the range of 30-35℃.

3. The method for preparing a high-efficiency composite biocarbon source according to claim 1, characterized in that, In step 2, the liquid fermentation temperature is controlled at 33-38℃, the pH value at 5.5-6.5, the dissolved oxygen concentration is maintained at 1-2 mg / L, and intermittent stirring is used, stirring for 5-10 minutes per hour, with a speed of 60-80 rpm and an aeration rate of 0.2-0.3 vvm.

4. The method for preparing a high-efficiency composite biocarbon source according to claim 1, characterized in that, It also includes a microbial community stabilization step: adding selective growth factors every 7-10 days, including cellobiose for primary degrading bacteria at an addition amount of 0.01-0.05%; glutamic acid and arginine for intermediate transforming bacteria at an addition amount of 0.02-0.1%; and trace elements such as manganese and molybdenum for terminal functional bacteria at an addition amount of 0.001-0.005%.

5. The method for preparing a high-efficiency composite biocarbon source according to claim 1, characterized in that, It also includes biological rhythm regulation steps: setting a 12-hour / 12-hour light-dark cycle with a light intensity of 100-200 lux; adding a mixed amino acid solution every 24 hours at a rate of 0.1-0.5% of the fermentation broth volume; and partially replacing 10-15% of the fermentation broth every 48 hours.

6. The method for preparing a high-efficiency composite biocarbon source according to claim 1, characterized in that, The porous carrier is activated carbon, volcanic rock, or zeolite, and the filling height is 10-15% of the height of the liquid fermentation reactor; the detoxification bacteria include Pseudomonas aeruginosa, white rot fungi, and Streptomyces, and the inoculum amount is 5-10% of the carrier mass.

7. The method for preparing a high-efficiency composite biocarbon source according to claim 1, characterized in that, It also includes a metabolic regulation step: adding 0.02-0.05% phenylalanine, 0.01-0.03% tyrosine and 0.01-0.02% tryptophan to the fermentation system once every 48 hours.

8. The method for preparing a high-efficiency composite biocarbon source according to claim 1, characterized in that, It also includes inhibitor monitoring and control steps: every 72 hours, the concentration of inhibitors such as total phenol, furfural, and hydroxymethylfurfural in the system is detected; when the inhibitor concentration exceeds the set threshold, the amount of detoxifying bacteria inoculated is increased, the reflux ratio is reduced, and the amount of metabolic precursor substances added is increased.

9. An application of a highly efficient composite biocarbon source prepared by the method according to any one of claims 1-8, characterized in that, It is used in wastewater treatment.

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