A method and application for preparing a hydrothermal carbon-based functional nutrient substrate by combining steam explosion, hydrothermal carbonization and aerobic fermentation

Abstract

The present invention discloses a method and application for preparing a hydrothermal carbon-based functional nutrient matrix by steam explosion coordinated hydrothermal carbonization and aerobic fermentation, and belongs to the technical field of solid waste resource preparation. First, a mixture of distiller's grains and straw is subjected to steam explosion coordinated hydrothermal carbonization to obtain hydrothermal carbon with rich oxygen-containing functional groups on the surface; secondly, the hydrothermal carbon is subjected to aerobic fermentation and rapid humification to finally obtain a hydrothermal carbon-based functional nutrient matrix. The present invention has the following technical advantages: the raw materials are fully utilized, the loss of nutrients during the treatment process is reduced, and the shortcomings of preparing the matrix with single raw materials of distiller's grains and straw are overcome; the aerobic fermentation maturity time is greatly shortened; the matrix has rich pore structure and strong water and fertilizer retention capacity; the matrix maturity and humic acid content are both high, and the fertilizer effect is strong; the use of pesticides and fertilizers is reduced, and the cost is low, the energy consumption is low, and there is no environmental pollution.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource preparation of solid waste, and particularly relates to a method and application for preparing a hydrothermal carbon-based functional nutrient substrate by combining steam explosion, hydrothermal carbonization and aerobic fermentation. Background Art

[0002] At present, industrialized seedling raising has been gradually accepted by many insightful people in the agricultural field, which has greatly promoted the research on the application of seedling substrates. The commonly used substrate materials include peat, rock wool, vermiculite, perlite, bagasse, mushroom residue, gravel, ceramsite, etc. Rock wool and peat are the most widely used globally and are recognized as relatively ideal cultivation substrates in the world. However, with the large amount of use year by year, the negative effects on society and the ecological environment have become increasingly obvious. On the one hand, due to the non-degradability of rock wool, a large amount of use brings secondary pollution to the environment; on the other hand, peat is a non-renewable resource, and excessive exploitation has the risk of depletion. In recent years, the vegetable seedling raising industry in China has developed rapidly. About 2 / 3 of the vegetables produced throughout the year adopt seedling transplanting. The national demand for vegetable seedling transplants exceeds 680 billion plants, while the current supply of intensively raised seedlings is about 200 billion plants, and the annual demand for solid substrates is about 150 million cubic meters, more than 80% of which need to be imported. Therefore, the domestic demand for substrates is huge, with an annual substrate gap of 120 million cubic meters, about 45 million tons. However, the current domestic production of commercial solid substrates is less than 10 million cubic meters, less than 1 / 10 of the demand, seriously restricting the development of the seedling (seedling) industry in China. Therefore, seeking and exploring excellent new seedling raising or cultivation substrates that are cheap, easily available, and can replace polluting materials such as rock wool or non-renewable resources such as peat has become one of the research hotspots of current scientific researchers.

[0003] Distillers' grains are the largest source of waste for major brewing enterprises, characterized by large quantity and concentration, with an annual output exceeding 100 million tons. If not treated in time, they will deteriorate, not only wasting resources but also polluting the environment. Distillers' grains are rich in nutrients such as protein, fat, cellulose, mineral elements, and a small amount of starch, and are important raw materials with great development prospects for functional nutrient substrates in protected agriculture. For example, CN102229516B, CN107251823A, CN103086755B, CN102910975B, etc. have all disclosed methods for preparing substrates using distillers' grains, all of which use the aerobic fermentation method, which has the disadvantages of long cycle, poor winter effect, large floor area, and uneven fermentation. In addition, distillers' grains stored for a long time will also contain eggs, germs, viruses, etc. Direct aerobic fermentation and composting can only reach 60 - 65°C, and the killing efficiency for Escherichia coli and Ascaris eggs is very low, thus endangering plant growth. Therefore, it is necessary to innovate the existing technology for preparing substrates by aerobic fermentation of distillers' grains.

[0004] Steam Explosion technology is a technology that originates from the accelerated takeoff device of aircraft carriers and uses the steam ejection principle to pre-treat biomass through an explosion process. The specific technical features are as follows: ① It generates shock waves accompanied by explosion sounds, and the time difference realizes the pressure difference; ② It realizes the conversion of heat and work, the temperature of the exploded materials drops significantly, and the expansion enthalpy changes to produce mechanical shear work. Features: The explosion speed reaches 0.00875 seconds; the instantaneous explosion power reaches an astonishing 22MW, while the thermal spray tank technology is only 0.026MW; it can break the microstructure of biomass instantly with low energy consumption, so that it can be degraded quickly. Therefore, steam explosion technology is a revolution in the field of pretreatment technology, and its advantages are reflected in: 1) significant effect: the degree of wall breaking, crystallinity, and degree of hydrolysis are significantly better than other technologies; 2) low energy consumption: the material energy consumption is only 0.1 tons of steam, and the cost is 30 to 50 yuan; 3) large scale: the standard production layout reaches a daily processing scale of thousands of tons, and the investment is 20% of the chemical method; 4) pure physical operation: it works with high-speed shock waves, and no chemicals are added during the whole process. Advantages of steam explosion technology for treating wine lees: ① Lignin, cellulose, and hemicellulose in biomass are instantly exploded by water vapor on the basis of full softening, and the three-element entangled structure is completely separated; ② not only surpasses the simple ripening and puffing treatment process, but also the macromolecular level fracture that occurs has brought revolutionary changes to biological fermentation; ③ The protein that is easy to produce odor is solidified into carbon to avoid the generation of odor and no "three wastes" are discharged.

[0005] In the prior art: CN106905007A discloses a method for producing a seedling medium using high temperature anaerobic distiller's grains as the main raw material, wherein the high temperature anaerobic distiller's grains are transported to a steam explosion machine for steam explosion treatment to obtain the high temperature anaerobic distiller's grains after steam explosion, and the high temperature anaerobic distiller's grains after steam explosion pretreatment are piled into strips, the fermented material is spread out to dry, sieved through a 2 cm sieve, mixed with vermiculite and perlite, and stirred evenly to obtain the seedling medium. However, the disadvantages of this technology are that the overall stacking time exceeds 30 days; due to the presence of two rice husks, the water retention performance is poor; the overall organic matter content is low (~38%), and a large amount of difficult-to-degrade vermiculite and perlite are mixed in. Summary of the invention

[0006] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a method and application of preparing a hydrothermal carbon-based functional nutrient matrix by steam explosion synergistic hydrothermal carbonization and aerobic fermentation, which can solve the problems of impurity pollution, poor water and fertilizer retention performance, and low organic matter content in the prior art process.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention discloses a method for preparing a hydrothermal carbon-based functional nutrient matrix by steam explosion coordinated hydrothermal carbonization and aerobic fermentation, comprising the following steps:

[0009] 1) Mix distillers' grains and straws in a mass ratio of 1:2 - 2:1, then conduct steam explosion treatment, separate and collect to obtain solid products and slurry products. Centrifuge and dehydrate the slurry products to obtain solids and filtrates, and mix the solids with the aforementioned solid products to obtain hydrothermal carbon;

[0010] 2) Mix the hydrothermal carbon and biological fermentation inoculant in a mass ratio of 1:20, then conduct stacking fermentation treatment, and dehydrate the fermentation products to obtain the hydrothermal carbon-based functional nutrient substrate.

[0011] Preferably, the steam explosion treatment uses an instantaneous ejection type steam blasting machine, and the conditions are: the explosion speed reaches 0.00875 s, the temperature is 180 - 260 °C, the steam pressure is 1.0 - 2.5 MPa, and the pressure holding time is 5 - 20 min.

[0012] Preferably, in step 1), the distillers' grains used are fresh white liquor distillers' grains, beer distillers' grains, yellow rice wine distillers' grains or red wine distillers' grains.

[0013] Preferably, in step 1), the straws used are crop straws, and are one or more of wheat straws, corn straws, rice straws, soybean straws, potato straws, cotton straws, tomato straws and sugarcane straws, and the particle size of the crop straws is 5 - 50 meshes.

[0014] Preferably, in step 1), the properties of the obtained hydrothermal carbon are as follows: the moisture content is 40% - 50%, the temperature is 50 - 60 °C, the C / N ratio is 20:1 - 30:1, and the humic acid content is 30% - 40%.

[0015] Preferably, in step 1), during the process of centrifuging and dehydrating the slurry products to obtain solids and filtrates, the obtained filtrate is used to adjust the moisture content of the hydrothermal carbon to 55% - 65%.

[0016] Preferably, in step 2), the biological fermentation inoculant used is prepared from 1 part of fermentation inoculant, 5 parts of brown sugar and 100 parts of water by mass; among them, the fermentation inoculant is one or several of Bacillus subtilis, Bacillus licheniformis, Aspergillus niger, Bacillus pumilus, Pseudomonas stutzeri, Aspergillus oryzae and Rhodococcus.

[0017] Preferably, in step 2), the time of the stacking fermentation treatment is 3 - 5 days.

[0018] The present invention also discloses a hydrothermal carbon-based functional nutrient substrate prepared by the method of steam explosion combined with hydrothermal carbonization and aerobic fermentation as described above. The physical properties of the hydrothermal carbon-based functional nutrient substrate are as follows: bulk density 0.3 - 0.4 g / cm3, total porosity 80% - 92%, aeration porosity 60% - 70%, water-holding porosity > 45%, air-water ratio 2:1 - 3:1, relative water content < 35%, cation exchange capacity calculated as NH4+ 20 - 30 cmol / kg, particle size < 20 mm; the chemical properties of the hydrothermal carbon-based functional nutrient substrate are as follows: humic acid content 60% - 70 wt%, pH value 6.0 - 6.8, conductivity 0.1 - 0.2 mS / cm, organic matter 85% - 90%, hydrolyzable nitrogen 200 - 300 mg / kg, available phosphorus 50 - 80 mg / kg, available potassium 280 - 400 mg / kg, mass ratio of nitrate nitrogen / ammonium nitrogen (4 - 6):1, exchangeable calcium 100 - 150 mg / kg, exchangeable magnesium 50 - 80 mg / kg.

[0019] The present invention also discloses the application of the above-mentioned hydrothermal carbon-based functional nutrient substrate in the preparation of a seedling-raising substrate or a cultivation substrate.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The method for preparing a hydrothermal carbon-based functional nutrient substrate by steam explosion combined with hydrothermal carbonization and aerobic fermentation disclosed by the present invention first performs steam explosion combined with hydrothermal carbonization treatment on the mixture of distiller's grains and straw to obtain hydrothermal carbon rich in oxygen-containing functional groups on the surface, and then performs aerobic fermentation and rapid humification treatment on the hydrothermal carbon to prepare a hydrothermal carbon-based functional nutrient substrate. The method of the present invention can make full use of raw materials, reduce the loss of nutrient elements during the treatment process, overcome the deficiencies of using distiller's grains and straw as single raw materials to prepare substrates, achieve the complete inactivation of pathogenic bacteria and plant seeds, avoid potential weeds and pests in the substrate, and greatly shorten the aerobic fermentation and composting time. The advantages of this method are analyzed as follows:

[0022] 1) Aiming at the problem that organic matter cannot be completely carbonized during the steam explosion carbonization process of using distiller's grains alone, and nitrogen elements are easily lost due to the residue of hydrolyzed protein in the aqueous phase after hydrolysis, by adding straw to the distiller's grains, the reducing polysaccharides obtained by straw hydrolysis and the amino acids obtained by hydrolysis of distiller's grains crude protein undergo the Maillard reaction to strengthen the carbonization of organic matter into carbon, which can solidify organic carbon to the greatest extent, making the organic matter content reach 90%, reducing secondary pollution, and at the same time being able to retain more nitrogen elements in the hydrothermal carbon, and 80% of the nitrogen in the raw materials is retained in the hydrothermal carbon;

[0023] 2) Aiming at the problems that the proportion of rice husk in distillers' grains is large, the hydrothermal carbon obtained by single hydrothermal carbonization has fewer pore structures and poor water and fertilizer retention performance. By adding straw, the oxygen-containing functional groups on the surface of hydrothermal carbon can be increased, accounting for more than 60%, and its water and fertilizer retention performance can be improved.

[0024] 3) Using the acidic substances produced by straw hydrolysis to promote the degradation of organic macromolecules in distillers' grains, the aerobic fermentation and humification time of the subsequent hydrothermal carbon can be shortened to 3-5 days, and the humic acid content can reach 60%-70wt%. The hydrothermal carbon-based functional nutrient substrate prepared by the method of the present invention has excellent physical and chemical property indexes, rich pore structures, strong water and fertilizer retention capabilities; the degree of substrate maturity and the humic acid content are both relatively high, and the fertilizer efficiency is strong. Therefore, it is very suitable for use as a seedling raising or cultivation substrate, can effectively reduce the use of pesticides and fertilizers, makes full use of waste resources, and has the advantages of low cost, low energy consumption, and no environmental pollution. Specific embodiments

[0025] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

[0026] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention described herein can be implemented in an order other than those described herein. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0027] A method for preparing a hydrothermal carbon-based functional nutrient substrate by steam explosion combined with hydrothermal carbonization and aerobic fermentation disclosed by the present invention specifically includes the following steps:

[0028] (1) Co-producing hydrothermal carbon by steam explosion of distillers' grains and straw in combination with hydrothermal carbonization

[0029] First, mix distiller's grains and straw in a certain proportion evenly and place them in an in-situ steam explosion machine. Keep them under a certain steam pressure for a period of time, and then rapidly release the pressure. Secondly, collect the solid products in the basket of the steam explosion chamber and the slurry products in the steam explosion bin and the pressure buffer bin, and centrifuge and dehydrate the slurry products to obtain solids and filtrate. Finally, mix the solid products in the basket and the solids obtained by centrifuging and separating the slurry products to obtain hydrothermal carbon.

[0030] (2) Rapid humification of hydrothermal carbon by aerobic fermentation to prepare functional nutrient substrates

[0031] First, mix hydrothermal carbon and biological fermentation inoculant in a certain proportion and stack them for fermentation, and keep them at a certain temperature for a certain time. Secondly, centrifuge and dehydrate the fermentation products to remove part of the water, and finally obtain hydrothermal carbon-based functional nutrient substrates.

[0032] Example 1

[0033] During the preparation of hydrothermal carbon, the steam explosion machine selected is an instantaneous ejection type steam explosion machine, with an explosion speed reaching 0.00875 s, the mass ratio of liquor distiller's grains to wheat straw being 1:2, the temperature being 180 °C, the steam pressure being 1.0 MPa, and the pressure holding time being 20 min. The properties of the finally obtained hydrothermal carbon are as follows: water content 50 wt%, temperature 50 °C, C / N ratio 30:1, and humic acid content 30 wt%.

[0034] Then prepare the fermentation broth according to the ratio of 1 part of biological fertilizer fermentation agent (a mixed inoculant prepared according to the mass ratio of Bacillus subtilis, Bacillus licheniformis and Aspergillus oryzae being 1:1:1) + 5 parts of brown sugar + 100 parts of water. Mix the solid phase product obtained after steam explosion with the prepared biological fertilizer fermentation broth evenly at a ratio of 1:20, and stack and ferment for 5 days. During the fermentation process, use the liquid phase obtained after steam explosion to adjust the water content of the mixed materials to 60%, and after fermentation, spread them out to dry until the water content is ~30%, and crush them through a 5-mesh sieve (particle size about 4 mm).

[0035] Example 2

[0036] During the preparation of hydrothermal carbon, the steam explosion machine selected is an instantaneous ejection type steam explosion machine, with an explosion speed reaching 0.00875 s, the mass ratio of liquor distiller's grains to wheat straw being 1:1, the temperature being 240 °C, the steam pressure being 2.0 MPa, and the pressure holding time being 15 min. The properties of the finally obtained hydrothermal carbon are as follows: water content 45 wt%, temperature 55 °C, C / N ratio 20:1, and humic acid content 35 wt%.

[0037] Then, prepare the fermentation broth according to the ratio of 1 part of biological bacterial fertilizer fermenter (a mixed bacterial agent prepared according to the mass ratio of Bacillus subtilis, Bacillus licheniformis and Aspergillus oryzae of 1:1:1) + 5 parts of brown sugar + 100 parts of water. Mix the solid-phase product obtained after steam explosion with the prepared biological bacterial fertilizer fermentation broth evenly at a ratio of 1:20, and stack and ferment for 4 days. During the fermentation process, use the liquid phase obtained after steam explosion to adjust the water content of the mixed material to 60%. After fermentation is completed, spread it out to dry until the water content is ~30%, and crush it through a 5-mesh sieve (particle size about 4 mm).

[0038] Example 3

[0039] During the preparation of hydrothermal carbon, the steam explosion machine selected is an instantaneous ejection type steam explosion machine, with an explosion speed reaching 0.00875 s, the mass ratio of liquor distiller's grains to wheat straw being 2:1, the temperature being 260 °C, the steam pressure being 2.5 MPa, and the pressure holding time being 5 min; the properties of the finally obtained hydrothermal carbon are as follows: water content 40 wt%, temperature 60 °C, C / N ratio 30:1, humic acid content 40 wt%.

[0040] Then, prepare the fermentation broth according to the ratio of 1 part of biological bacterial fertilizer fermenter (a mixed bacterial agent prepared according to the mass ratio of Bacillus licheniformis and Aspergillus oryzae of 1:1) + 5 parts of brown sugar + 100 parts of water. Mix the solid-phase product obtained after steam explosion with the prepared biological bacterial fertilizer fermentation broth evenly at a ratio of 1:20, and stack and ferment for 3 days. During the fermentation process, use the liquid phase obtained after steam explosion to adjust the water content of the mixed material to 60%. After fermentation is completed, spread it out to dry until the water content is ~30%, and crush it through a 5-mesh sieve (particle size about 4 mm).

[0041] Example 4

[0042] During the preparation of hydrothermal carbon, the steam explosion machine selected is an instantaneous ejection type steam explosion machine, with an explosion speed reaching 0.00875 s, the mass ratio of liquor distiller's grains to wheat straw being 1:2, the temperature being 200 °C, the steam pressure being 1.5 MPa, and the pressure holding time being 20 min; the properties of the finally obtained hydrothermal carbon are as follows: water content 48 wt%, temperature 60 °C, C / N ratio 25:1, humic acid content 30 wt%.

[0043] Then, prepare the fermentation broth according to the ratio of 1 part of biological bacterial fertilizer fermenter (a mixed bacterial agent prepared according to the mass ratio of Pseudomonas stutzeri, Bacillus licheniformis and Rhodococcus of 1:1:1) + 5 parts of brown sugar + 100 parts of water. Mix the solid-phase product obtained after steam explosion with the prepared biological bacterial fertilizer fermentation broth evenly at a ratio of 1:20, and stack and ferment for 5 days. During the fermentation process, use the liquid phase obtained after steam explosion to adjust the water content of the mixed material to 60%. After fermentation is completed, spread it out to dry until the water content is ~30%, and crush it through a 5-mesh sieve (particle size about 4 mm).

[0044] Example 5

[0045] During the preparation of hydrothermal carbon, the steam explosion machine selected is an instantaneous ejection type steam explosion machine, with an explosion speed reaching 0.00875 s, the mass ratio of liquor distiller's grains to corn straw being 2:1, the temperature being 200 °C, the steam pressure being 1.5 MPa, and the pressure holding time being 15 min; the properties of the finally obtained hydrothermal carbon are as follows: moisture content 50 wt%, temperature 60 °C, C / N ratio 30:1, and humic acid content 30 wt%.

[0046] Then prepare the fermentation broth according to the ratio of 1 part of biological bacterial fertilizer fermenting agent (a mixed bacterial agent prepared by mixing Bacillus licheniformis and Aspergillus niger in a mass ratio of 1:1) + 5 parts of brown sugar + 100 parts of water. Mix the solid-phase product obtained after steam explosion with the prepared biological bacterial fertilizer fermentation broth evenly at a ratio of 1:20, and stack and ferment for 5 days. During the fermentation process, use the liquid phase obtained after steam explosion to adjust the water content of the mixed materials to 60%, and after fermentation is completed, air-dry to a water content of ~30%, and crush and pass through a 5-mesh sieve (particle size about 4 mm).

[0047] Example 6

[0048] During the preparation of hydrothermal carbon, the steam explosion machine selected is an instantaneous ejection type steam explosion machine, with an explosion speed reaching 0.00875 s, the mass ratio of liquor distiller's grains to corn straw being 1:1, the temperature being 240 °C, the steam pressure being 2.0 MPa, and the pressure holding time being 20 min; the properties of the finally obtained hydrothermal carbon are as follows: moisture content 42 wt%, temperature 60 °C, C / N ratio 32:1, and humic acid content 40 wt%.

[0049] Then prepare the fermentation broth according to the ratio of 1 part of biological bacterial fertilizer fermenting agent (Bacillus pumilus) + 5 parts of brown sugar + 100 parts of water. Mix the solid-phase product obtained after steam explosion with the prepared biological bacterial fertilizer fermentation broth evenly at a ratio of 1:20, and stack and ferment for 3 days. During the fermentation process, use the liquid phase obtained after steam explosion to adjust the water content of the mixed materials to 60%, and after fermentation is completed, air-dry to a water content of ~30%, and crush and pass through a 5-mesh sieve (particle size about 4 mm).

[0050] Example 7

[0051] During the preparation of hydrothermal carbon, the steam explosion machine selected is an instantaneous ejection type steam explosion machine, with an explosion speed reaching 0.00875 s, the mass ratio of liquor distiller's grains to corn straw being 2:1, the temperature being 260 °C, the steam pressure being 2.5 MPa, and the pressure holding time being 10 min; the properties of the finally obtained hydrothermal carbon are as follows: moisture content 39 wt%, temperature 60 °C, C / N ratio 30:1, and humic acid content 40 wt%.

[0052] Then, prepare the fermentation broth according to the ratio of 1 part of biological bacterial fertilizer fermenting agent (a mixed bacterial agent prepared according to the mass ratio of Bacillus subtilis, Bacillus licheniformis and Aspergillus oryzae equal to 1:1:1) + 5 parts of brown sugar + 100 parts of water. Mix the solid-phase product obtained after steam explosion with the prepared biological bacterial fertilizer fermentation broth evenly at a ratio of 1:20, and stack and ferment for 3 days. During the fermentation process, use the liquid phase obtained after steam explosion to adjust the water content of the mixed materials to 60%, and after fermentation is completed, spread out and air-dry until the water content is ~30%, and crush and pass through a 5-mesh sieve (particle size about 4 mm).

[0053] Example 8

[0054] During the preparation process of hydrothermal carbon, the steam explosion machine selected is an instantaneous ejection type steam explosion machine, with an explosion speed reaching 0.00875 s, the mass ratio of liquor lees / corn straw being 1:2, the temperature being 240 °C, the steam pressure being 2.0 MPa, and the pressure maintaining time being 10 min; the properties of the finally obtained hydrothermal carbon are as follows: water content 42 wt%, temperature 60 °C, C / N ratio 27:1, and humic acid content 40 wt%.

[0055] Then, prepare the fermentation broth according to the ratio of 1 part of biological bacterial fertilizer fermenting agent (a mixed bacterial agent prepared according to the mass ratio of Bacillus subtilis, Bacillus licheniformis and Aspergillus oryzae equal to 1:1:1) + 5 parts of brown sugar + 100 parts of water. Mix the solid-phase product obtained after steam explosion with the prepared biological bacterial fertilizer fermentation broth evenly at a ratio of 1:20, and stack and ferment for 4 days. During the fermentation process, use the liquid phase obtained after steam explosion to adjust the water content of the mixed materials to 60%, and after fermentation is completed, spread out and air-dry until the water content is ~30%, and crush and pass through a 5-mesh sieve (particle size about 4 mm).

[0056] Detect the carbon-based seedling-raising substrates prepared in the above specific Examples 1-8 according to the national standard for vegetable seedling-raising substrates, and the results are shown in Table 1:

[0057] Table 1 Physical and chemical properties of the samples prepared in specific Examples 1-8

[0058]

[0059]

[0060] As can be seen from Table 1, the seedling-raising substrate prepared from liquor lees and straw as raw materials in the present invention has stable quality, meets the national standard for vegetable seedling-raising substrates, has rich sources, low cost, simple process, and is easy for batch production in factories.

[0061] The above content is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a hydrothermal carbon-based functional nutrient substrate by steam explosion combined with hydrothermal carbonization and aerobic fermentation, characterized in that, Including the following steps: 1) After mixing distiller's grains and straw in a mass ratio of 1:2 - 2:1, perform steam explosion treatment, separate and collect to obtain a solid product and a slurry product. Centrifuge and dehydrate the slurry product to obtain a solid and a filtrate. Mix the solid with the aforementioned solid product to obtain hydrothermal carbon. The properties of the prepared hydrothermal carbon are as follows: water content is 40% - 50%, temperature is 50 - 60 °C, C / N ratio is 20:1 - 30:1, and humic acid content is 30% - 40%; The steam explosion treatment uses an instantaneous ejection type steam exploder, with the conditions: explosion speed reaches 0.00875 s, temperature is 180 - 260 °C, steam pressure is 1.0 - 2.5 MPa, and pressure holding time is 5 - 20 min; After centrifuging and dehydrating the slurry product to obtain a solid and a filtrate, adjust the water content of the hydrothermal carbon in the filtrate to 55% - 65%; 2) Mix the hydrothermal carbon and a biological fermentation inoculant in a mass ratio of 1:20, then perform stacking fermentation treatment, and dehydrate the fermentation product to obtain a hydrothermal carbon-based functional nutrient substrate.

2. The method for preparing a hydrothermal carbon-based functional nutrient substrate by steam explosion combined with hydrothermal carbonization and aerobic fermentation according to claim 1, characterized in that, In step 1), the distiller's grains used are fresh white wine distiller's grains, beer distiller's grains, yellow rice wine distiller's grains, or red wine distiller's grains.

3. The method for preparing a hydrothermal carbon-based functional nutrient substrate by steam explosion combined with hydrothermal carbonization and aerobic fermentation according to claim 1, characterized in that, In step 1), the straw used is crop straw, which is one or more of wheat straw, corn straw, rice straw, soybean straw, potato straw, cotton straw, tomato straw, and sugarcane straw, and the particle size of the crop straw is 5 - 50 mesh.

4. The method for preparing a hydrothermal carbon-based functional nutrient substrate by steam explosion combined with hydrothermal carbonization and aerobic fermentation according to claim 1, characterized in that, In step 2), the biological fermentation inoculant used is prepared by mixing 1 part of fermentation inoculant, 5 parts of brown sugar, and 100 parts of water by mass; among them, the fermentation inoculant is one or several of Bacillus subtilis, Bacillus licheniformis, Aspergillus niger, Bacillus pumilus, Pseudomonas stutzeri, Aspergillus oryzae, and Rhodococcus.

5. The method for preparing a hydrothermal carbon-based functional nutrient substrate by steam explosion combined with hydrothermal carbonization and aerobic fermentation according to claim 1, characterized in that, In step 2), the time for stacking fermentation treatment is 3 - 5 days.

6. A hydrothermal carbon-based functional nutrient substrate prepared by the method for preparing a hydrothermal carbon-based functional nutrient substrate by steam explosion combined with hydrothermal carbonization and aerobic fermentation according to any one of claims 1 to 5, characterized in that, The physical properties of the hydrothermal carbon-based functional nutrient substrate are as follows: bulk density 0.3 - 0.4 g / cm 3 , total porosity 80% - 92%, aeration porosity 60% - 70%, water-holding porosity > 45%, air-water ratio 2:1 - 3:1, relative water content < 35%, cation exchange capacity calculated as NH4 + is 20 - 30 cmol / kg, particle size < 20 mm; the chemical properties of the hydrothermal carbon-based functional nutrient substrate are as follows: humic acid content 60% - 70 wt%, pH value 6.0 - 6.8, conductivity 0.1 - 0.2 mS / cm, organic matter 85% - 90%, hydrolyzable nitrogen 200 - 300 mg / kg, available phosphorus 50 - 80 mg / kg, available potassium 280 - 400 mg / kg, mass ratio of nitrate nitrogen to ammonium nitrogen (4 - 6):1, exchangeable calcium 100 - 150 mg / kg, exchangeable magnesium 50 - 80 mg / kg.

7. Application of the hydrothermal carbon-based functional nutrient substrate according to claim 6 in preparing a seedling-raising substrate or a cultivation substrate.

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