Multi-source organic solid waste nutrient soil as well as preparation method and application thereof

Abstract

The invention provides multi-source organic solid waste nutrient soil and a preparation method and application thereof, and the preparation method comprises the following specific steps: S1, removing foreign matters from blue-green algae and livestock and poultry manure, crushing, mixing with residual sludge of a sewage plant, adding an alkaline solution, and fully stirring; s2, adding an iron ion solution into the mixture stirred in the step S1, and fully stirring to obtain a pretreated nutrient soil base material; s3, adding the nutrient soil base material pretreated in the S2 into a dry anaerobic reactor, stirring in a medium-temperature environment or a high-temperature environment, and carrying out anaerobic fermentation; s4, carrying out solid-liquid separation treatment on the nutrient soil base material subjected to anaerobic fermentation in S3 to obtain biogas slurry and biogas residues; and S5, performing aerobic composting on the biogas residues obtained in the step S4 to obtain the multi-source organic solid waste nutrient soil. According to the nutrient soil prepared by the method, the preparation raw materials are easy to obtain, the product quality is high, and recycling and industrial popularization and application of organic solid waste are facilitated.

Description

Technical Field

[0001] This invention belongs to the field of green recycling of waste, specifically involving multi-source organic solid waste nutrient soil, its preparation method and application. Background Technology

[0002] Currently, multi-source organic fertilizers prepared primarily from poultry manure and other organic waste are widely used in agricultural planting. However, related technologies mostly focus on the conversion and utilization of everyday agricultural waste, lacking diversity in raw material sources, especially the recycling and reuse of other organic solid wastes such as cyanobacteria caused by eutrophication and residual sludge from municipal sewage treatment. Furthermore, the high water content, difficulty in dehydration, and high processing costs of materials like cyanobacteria and sludge have hindered the industrialization of related recycling technologies. Summary of the Invention

[0003] To address the current challenges, this invention provides a multi-source organic solid waste nutrient soil, its preparation method, and its application. It uses cyanobacteria, residual sludge from municipal wastewater treatment plants, and other agricultural waste as raw materials. After pretreatment with alkaline and ferric chloride solutions, the soil undergoes dry anaerobic fermentation and aerobic composting processes to generate multi-source organic solid waste nutrient soil, which is then used for returning to the fields. This effectively utilizes the nutrients in organic waste and promotes the green recycling of resources.

[0004] Specifically, the first aspect of the present invention provides a method for preparing multi-source organic solid waste nutrient soil, comprising the following specific steps: S1: after removing foreign matter from cyanobacteria and livestock and poultry manure, crush them, mix them with residual sludge from sewage treatment plants, add an alkaline solution, and stir thoroughly; S2: add an iron ion solution to the mixture after stirring in S1 and stir thoroughly to obtain pretreated nutrient soil base material; S3: add the pretreated nutrient soil base material in S2 to a dry anaerobic reactor, stir in a mesophilic or high-temperature environment, and carry out anaerobic fermentation; S4: perform solid-liquid separation treatment on the nutrient soil base material after anaerobic fermentation in S3 to obtain biogas slurry and biogas residue; S5: perform aerobic composting on the biogas residue obtained in S4 to obtain multi-source organic solid waste nutrient soil.

[0005] Optionally, S1 specifically includes: the alkaline solution is a Ca(OH)2 solution; the stirring frequency is 10 r / min, and the stirring time is 30 min.

[0006] Optionally, S1 specifically includes adding 16-40 kg of Ca(OH)2 solution to each 1 t mixture of cyanobacteria, livestock and poultry manure and residual sludge, wherein the mass percentage of the Ca(OH)2 solution is 1%-5%wt.

[0007] Optionally, S2 specifically includes: the iron ion solution is a FeCl3 solution; specifically, 8-20 kg of FeCl3 solution is added to the mixture after stirring in S1, wherein the mass percentage of the FeCl3 solution is 0.1-0.5 wt%; the stirring frequency is 10 r / min and the stirring time is 30 min.

[0008] Optionally, S3 specifically includes: controlling the moisture content of the nutrient soil substrate at the feed cylinder of the dry anaerobic reactor to 80%; the mesophilic ambient temperature to be 35-40℃, and the high-temperature ambient temperature to be 50-55℃; the stirring frequency of the dry anaerobic reactor to be 2 r / min, the pH value in the dry anaerobic reactor to be controlled at 7.8-8.4, the ratio of volatile fatty acids (VFA) to alkalinity to be controlled at 0.1-0.4, and the sludge retention time to be controlled at 20-30 days.

[0009] Optionally, the aerobic composting area is divided into a heating stage, a high-temperature stage, a cooling stage, and a maturation stage; wherein, the pH value of the heating stage is controlled at 6.5; the pH value of the high-temperature stage is controlled at 7.5~8.5, and the temperature is maintained above 60℃; and the pH value of the maturation stage is controlled at 7~7.5.

[0010] Optionally, S5 specifically includes: controlling the oxygen concentration in the compost at 10-15% throughout the entire aerobic composting process.

[0011] Optionally, S5 specifically includes: adding auxiliary materials to the biogas residue during the aerobic composting process, wherein the auxiliary materials are sawdust or straw; wherein the biogas residue and auxiliary materials are mixed in a mass ratio of 1:0.5-1.

[0012] A second aspect of the present invention provides a multi-source organic solid waste nutrient soil prepared according to the preparation method described above.

[0013] The third aspect of this invention provides an application of the multi-source organic solid waste nutrient soil in the field of green recycling of waste, specifically for improving compacted and acidified soil, and increasing soil organic matter content and microbial activity.

[0014] The present invention has the following beneficial effects: 1. Using cyanobacteria from eutrophic water bodies and industrial solid waste from sewage treatment as basic raw materials, combined with agricultural organic waste for mixed fermentation, it effectively solves the pollution of cyanobacterial blooms and the recycling of sewage treatment fertilizers, realizing the resource cycle and energy self-sufficiency of sewage treatment plants. Returning nutrient soil to the field can effectively alleviate the damage to the soil caused by long-term application of chemical fertilizers and increase crop yields.

[0015] 2. The organic solid waste mixture was pretreated by successively using alkaline solution and iron ion solution. The addition of alkaline solution can effectively destroy the cell wall of cyanobacteria and reduce the water content of cyanobacteria. Subsequently, the addition of iron ion solution can promote direct interspecies electron transfer among microorganisms in the mixture, improve the methane yield of anaerobic digestion, and at the same time reduce the problem of pH increase of raw materials caused by the addition of alkaline solution. This effectively ensures the quality of the prepared nutrient soil. At the same time, the raw materials are easy to obtain, the production process is environmentally friendly, and the product yield is high, which is conducive to the realization of industrial application.

[0016] Furthermore, additional advantages, objects, and features of the invention will be set forth in part in the description which follows, and will also become apparent in part to those skilled in the art upon studying the following text, or may be learned by practice of the invention. The objects and other advantages of the invention can be realized and obtained by means of the structures and method steps specifically pointed out in the written description, claims, and drawings.

[0017] Those skilled in the art will understand that the objectives and advantages achievable with the present invention are not limited to those specifically described above, and that the above and other objectives achievable with the present invention will become clearer from the following detailed description. Attached Figure Description

[0018] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, are not intended to limit the scope of the invention.

[0019] Figure 1 This is a flowchart illustrating the preparation method of multi-source organic solid waste nutrient soil in an embodiment of the present invention; Figure 2 This is a table showing the composition analysis of the multi-source organic solid waste nutrient soil in Example 1 of the present invention; Figure 3 These are on-site photos of the crop soil returning to the field test site in this embodiment of the invention; Figure 4 This is a schematic diagram showing the specific location of the crop soil returning to the field test site in an embodiment of the present invention; Figure 5 This is a table showing the measured yield of rice under three farming scenarios in this invention embodiment; Figure 6 The amylose and crude protein content of rice obtained from cultivation under three different farming scenarios in this embodiment of the invention; Figure 7 This is a comparative test result of the heavy metal content of rice seeds obtained under the T1 and T2 farming scenarios in this embodiment of the invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are used to explain the invention, but are not intended to limit the invention. It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only structures and / or processing steps closely related to the solutions according to the invention are shown in the accompanying drawings, while other details not closely related to the invention are omitted.

[0021] It should be emphasized that the term "including / comprises" as used herein refers to the presence of a feature, element, step, or component, but does not exclude the presence or addition of one or more other features, elements, steps, or components.

[0022] Combined with appendix Figure 1 As shown, one aspect of the present invention provides a method for preparing multi-source organic solid waste nutrient soil, comprising the following specific steps: S1: After removing foreign matter from cyanobacteria and livestock and poultry manure, crush them, mix them with residual sludge from sewage treatment plants, add an alkaline solution, and stir thoroughly; S2: Add FeCl3 solution to the mixture after stirring in S1 and stir thoroughly to obtain pretreated nutrient soil base material; S3: Add the pretreated nutrient soil base material in S2 to a dry anaerobic reactor, stir in a mesophilic or high-temperature environment, and carry out anaerobic fermentation; S4: Perform solid-liquid separation treatment on the nutrient soil base material after anaerobic fermentation in S3 to obtain biogas slurry and biogas residue; S5: Perform aerobic composting on the biogas residue obtained in S4 to obtain multi-source organic solid waste nutrient soil.

[0023] Optionally, S1 specifically includes: an alkaline solution of Ca(OH)₂ solution; a stirring frequency of 10 r / min; and a stirring time of 30 min. A higher pH value can disrupt the cyanobacterial cell membrane, dissolve the extracellular polymers of the cyanobacteria, and effectively reduce the water content of the cyanobacteria. Furthermore, those skilled in the art should understand that the alkaline solution used here can also be selected from solutions that can achieve the same technical effect and adjust the alkalinity of the entire water body; for example, one or more of NaOH solution and Na₂CO₃ solution can be selected.

[0024] Optionally, S1 specifically includes: adding 16-40 kg of Ca(OH)2 solution to each 1 t mixture of cyanobacteria, livestock and poultry manure and residual sludge. The mass percentage of Ca(OH)2 solution is 1%-5%wt. Calcium ions can effectively compress the double electron layer on the surface of cyanobacteria, reduce the Zeta potential, and promote the aggregation and sedimentation of cyanobacteria.

[0025] Optionally, S2 specifically includes: the ferric ion solution is a FeCl3 solution; specifically, 8-20 kg of FeCl3 solution is added to the mixture after stirring in S1, the mass percentage of FeCl3 solution being 0.1-0.5 wt%; the stirring frequency is 10 r / min, and the stirring time is 30 min. In this step, the Fe in ferric chloride... 3+ Ions can be converted into Fe through reduction reactions. 2+ Fe ions can promote direct interspecies electron transfer (DIET) in microorganisms, accelerate the degradation of acidic substances (such as propionic acid / butyric acid) in mixtures, and increase the methane yield of anaerobic digestion. Additionally, Fe... 3+ Hydrolysis can also produce H + This avoids the problem of the pH value in the raw materials rising too quickly after the addition of calcium hydroxide. Furthermore, those skilled in the art will readily understand that the iron ion solution used here can also be selected to achieve the same technical effect, i.e., to introduce Fe into the mixture / liquid. 3+ Solutions of ions, such as Fe2SO4 solution, can also be chosen as an alternative.

[0026] Optionally, S3 specifically includes: controlling the moisture content of the nutrient soil substrate at the feed cylinder of the dry anaerobic reactor to 80%; maintaining a mesophilic ambient temperature of 35-40℃ and a hyperthermic ambient temperature of 50-55℃; setting the stirring frequency of the dry anaerobic reactor to 2 r / min; controlling the pH value in the dry anaerobic reactor to 7.8-8.4; controlling the ratio of volatile fatty acids (VFA) to alkalinity to 0.1-0.4; and controlling the sludge retention time (SRT) to 20-30 days. Here, when the initial moisture content of the mixture is higher than the ideal range (around 80%), the excess moisture content should be adjusted to the ideal range.

[0027] Optionally, aerobic composting is divided into a heating stage, a high-temperature stage, a cooling stage, and a maturation stage. During the heating stage, the pH is controlled at 6.5; during the high-temperature stage, the pH is controlled at 7.5-8.5, and the temperature is maintained above 60°C; during the maturation stage, the pH is controlled at 7-7.5. In some embodiments, the basic meaning and effects of the above stages of aerobic composting can be summarized as follows: a. Heating stage: During this process, aerobic microorganisms in the composting material multiply rapidly, decomposing organic matter and releasing heat, causing the compost temperature to rise. When the temperature reaches approximately 60°C, pathogens and insect eggs can be effectively killed, improving the overall quality of the compost material. b. High-temperature stabilization stage: When the compost temperature rises to the target temperature (above 60°C), the heat generated by the decomposition of organic matter and the heat exchanged with the external environment reach equilibrium, and the compost temperature remains stable at a relatively high temperature. During this stage, the types of microorganisms change, with meso- and thermophilic microorganisms becoming dominant. c. Cooling and Stabilization Stage: As organic matter gradually decomposes, the proportion of remaining organic matter in the compost decreases, reducing decomposition activity. The temperature gradually drops, and the activity of microorganisms gradually decreases. During this stage, the compost gradually matures, and organic matter decomposes to form effective fertilizer components and humus, gradually forming organic fertilizer. d. Maturation Stage: The organic matter in the compost further decomposes, forming humus. Nutrients also tend to stabilize, and the reaction ends.

[0028] Optionally, S5 specifically includes: controlling the oxygen concentration in the compost at 10-15% throughout the entire aerobic composting process.

[0029] Optionally, S5 specifically includes: adding auxiliary materials to the biogas residue during the aerobic composting process, the auxiliary materials being sawdust or straw; wherein the biogas residue and auxiliary materials are mixed in a mass ratio of 1:0.5-1. The auxiliary materials can also be selected from biomass agricultural wastes with similar composition to sawdust and straw, such as wood chips, rice straw, and coconut shell powder, to further achieve the purpose of recycling.

[0030] A second aspect of the present invention provides a multi-source organic solid waste nutrient soil prepared according to a preparation method.

[0031] The third aspect of this invention provides an application of multi-source organic solid waste nutrient soil in the field of green waste recycling, specifically for improving compacted and acidified soil, increasing soil organic matter content and microbial activity.

[0032] The present invention will be further described in detail below through specific embodiments and related comparative examples. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0033] Example 1 The specific process in this embodiment includes: Take 1 ton of cyanobacteria and livestock manure, remove foreign matter, crush them, mix them with wastewater treatment plant sludge, add 40 kg of 2% wt calcium hydroxide solution, and stir thoroughly at 10 r / min for 30 min. Add 20 kg of 0.2 wt ferric chloride solution to the stirred mixture, and stir thoroughly at 10 r / min for 30 min to obtain pretreated nutrient soil. Control the moisture content of the pretreated nutrient soil to 80%, add it to a dry anaerobic reactor, and stir under mesophilic or hyperthermic conditions for anaerobic fermentation. The stirring frequency of the anaerobic reactor is 2... The dry anaerobic reactor was operated at a speed of r / min, with the pH value controlled at 8.1, the pH ratio at 0.1, and the sludge retention time at 30 days. The nutrient soil substrate after anaerobic fermentation underwent solid-liquid separation to obtain biogas slurry and biogas residue. The biogas residue was then subjected to aerobic composting. During the heating phase of composting, the pH value was controlled at 6.5; during the high-temperature phase, the pH value was controlled at 8.0, and the temperature was maintained above 60℃; during the maturation phase, the pH value was controlled at 7.0. Throughout the aerobic composting process, the oxygen concentration in the compost was controlled at 10%. During aerobic composting, auxiliary materials were added to the biogas residue at a mass ratio of 1:0.3 to obtain multi-source organic solid waste nutrient soil.

[0034] Example 2 The steps in this embodiment are the same as those in Example 1, except that: 26 kg of 3% wt calcium hydroxide solution is added to every 1 t of mixture of cyanobacteria, livestock and poultry manure and residual sludge, followed by 13 kg of 0.3 wt% ferric chloride solution; the remaining reaction conditions and steps are the same as in Example 1.

[0035] Example 3 The steps in this example are the same as those in Example 1, except that: 1 ton of cyanobacteria, livestock and poultry manure and residual sludge are taken, 20 kg of 4% wt calcium hydroxide solution is added, and the mixture is stirred at 10 r / min for 30 min, and then 10 kg of 0.4 wt% ferric chloride solution is added; the remaining reaction conditions and steps are the same as in Example 1.

[0036] Example 4 The steps in this example are the same as those in Example 1, except that: 1 ton of cyanobacteria, livestock and poultry manure and residual sludge are taken, 16 kg of 5% wt calcium hydroxide solution is added, and the mixture is stirred at 10 r / min for 30 min, and then 8 kg of 0.5 wt% ferric chloride solution is added. The remaining reaction conditions and steps are the same as in Example 1.

[0037] like Figure 2As shown, this is a composition analysis table of the nutrient soil obtained by the preparation method in Example 1. It can be seen that the nutrient soil has a high organic matter content of 30.2%, which plays a key role in providing nutrients needed by plants and improving soil structure. In addition, the nutrient soil has low content of heavy metals and other pollutants, and the application of nutrient soil has little impact on soil and crops.

[0038] Furthermore, the nutrient soil prepared based on the above embodiments and specific implementation methods of the present invention can be used for returning crop soil to the field. Taking rice (commercially available Nanjing 46 type rice) as an example, the test site was selected at the intersection of Chengzhou Road and Huanbao Avenue in Yixing City, Wuxi City, Jiangsu Province (latitude and longitude 31.4N, 119.7E). The reclamation area has subtropical monsoon climate characteristics; the average annual temperature is 16.6℃, the average annual rainfall is 1177 mm, and the annual sunshine duration is 1937.7 hours. Figure 3 , 4 The test site is shown in on-site photos and a schematic diagram showing its specific location. Figure 5 The table shows the measured rice yield under the same natural conditions and farming methods in three farming scenarios: T1 (applying the nutrient soil prepared in Example 1); T2 (applying 49% (24-8-17) optimized formula fertilizer and 28% (16-0-12) nitrogen and potassium fertilizer); and T3 (not applying nutrient soil and fertilizer). Figure 6 The figures show the amylose and crude protein content of rice grown under three different farming scenarios. It is evident that the rice grown using the nutrient soil prepared according to this invention significantly increases the final yield compared to soils treated with ordinary commercial fertilizers and those without fertilizer. Furthermore, the main nutrient components of rice grown in soils treated with the nutrient soil prepared according to this invention are roughly the same as, and slightly higher than, those of rice grown in soils treated with chemical fertilizers, and significantly higher than those grown in rice grown without fertilizer. Figure 7 The results of comparative tests on heavy metal content in rice seeds obtained under T1 and T2 farming scenarios are further shown. According to standard requirements, the limit for cadmium and arsenic in grains is 0.2 mg / kg. This is to ensure that the cadmium content in food does not exceed the safe range, thereby reducing the health risks posed by cadmium intake. As can be seen, the cadmium content in the rice tested was less than or equal to 0.2 mg / kg. Therefore, the rice produced using the nutrient soil prepared in this embodiment meets the national food safety standards for cadmium limits.

[0039] This invention proposes a method for preparing nutrient soil for agricultural application using multi-source organic solid waste as raw materials, and the resulting nutrient soil and its application in green circular agriculture. The method utilizes common organic pollutants found in eutrophic water bodies, such as cyanobacteria and sludge from industrial wastewater treatment, as organic raw materials. The multi-source organic solid waste mixture undergoes a two-step pretreatment process. Specifically, firstly, a high-pH alkaline solution is used for pretreatment, which disrupts the cyanobacterial cell membrane, dissolves the extracellular polymers of the cyanobacteria, and effectively reduces the water content of the cyanobacteria. Simultaneously, the metal ions in the alkaline solution effectively compress the double electron layer on the surface of the cyanobacteria, reducing the zeta potential and promoting cyanobacterial aggregation and sedimentation. Subsequently, an iron ion solution introduces Fe... 3+ Ions can be reduced to Fe 2+ Fe ions can promote direct interspecies electron transport (DIET), accelerate the degradation of acidic substances such as propionic acid / butyric acid, and effectively improve the methane yield of anaerobic digestion. Additionally, Fe... 3+ Hydrolysis will produce H + This further reduces the problem of the overall pH value of the multi-source organic solid waste mixture rising after the addition of alkaline solution.

[0040] It should be clarified that the present invention is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of the present invention.

[0041] In this invention, features described and / or illustrated for one embodiment may be used in the same or similar manner in one or more other embodiments, and / or combined with or in place of features of other embodiments.

[0042] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing nutrient soil from multi-source organic solid waste, characterized in that, The specific steps include the following: S1: After removing foreign matter from blue-green algae and livestock and poultry manure, crush them, mix them with the remaining sludge from the sewage treatment plant, add an alkaline solution, and stir thoroughly. S2: Add iron ion solution to the mixture after stirring in S1 and stir thoroughly to obtain pretreated nutrient soil base material; S3: Add the pretreated nutrient soil substrate from S2 to the dry anaerobic reactor and stir it in a mesophilic or hyperthermic environment to carry out anaerobic fermentation. S4: The nutrient soil substrate after anaerobic fermentation in S3 is subjected to solid-liquid separation treatment to obtain biogas slurry and biogas residue; S5: The biogas residue obtained in S4 is aerobically composted to obtain multi-source organic solid waste nutrient soil.

2. The preparation method according to claim 1, characterized in that, S1 specifically includes: The alkaline solution is a Ca(OH)2 solution; The stirring frequency is 10 r / min and the stirring time is 30 min.

3. The preparation method according to claim 2, characterized in that, S1 specifically includes: Add 16-40 kg of Ca(OH)2 solution to every 1 ton of mixture of cyanobacteria, livestock and poultry manure and residual sludge, wherein the mass percentage of the Ca(OH)2 solution is 1%-5%wt.

4. The preparation method according to claim 3, characterized in that, S2 specifically includes: The iron ion solution is a FeCl3 solution; Specifically, 8-20 kg of FeCl3 solution is added to the stirred mixture in S1, wherein the mass percentage of the FeCl3 solution is 0.1-0.5 wt%. The stirring frequency is 10 r / min, and the stirring time is 30 min.

5. The preparation method according to claim 1, characterized in that, S3 specifically includes: The moisture content of the nutrient soil base material at the feed cylinder of the dry anaerobic reactor is controlled at 80%. The medium-temperature environment temperature is 35-40℃, and the high-temperature environment temperature is 50-55℃; The stirring frequency of the dry anaerobic reactor is 2 r / min, the pH value in the dry anaerobic reactor is controlled at 7.8~8.4, the ratio of volatile fatty acids to alkalinity is controlled at 0.1~0.4, the sludge retention time is controlled at 20~30 days, and stirring and pH control are maintained throughout the process.

6. The preparation method according to claim 1, characterized in that: The aerobic composting area is divided into a heating stage, a high-temperature stage, a cooling stage, and a maturation stage; The pH value during the heating phase is controlled at 6.

5. During the high-temperature stage, the pH is controlled at 7.5~8.5, and the temperature is maintained above 60℃. The pH during the composting stage is controlled at 7-7.

5.

7. The preparation method according to claim 6, characterized in that, S5 specifically includes: Throughout the entire aerobic composting process, the oxygen concentration in the compost is controlled at 10-15%.

8. The preparation method according to claim 7, characterized in that, S5 specifically includes: In the aerobic composting process, auxiliary materials are added to the biogas residue, and the materials of the auxiliary materials are sawdust or straw; The biogas residue and auxiliary materials are mixed in a mass ratio of 1:0.5-1.

9. A multi-source organic solid waste nutrient soil prepared by the preparation method according to any one of claims 1-8.

10. An application of the multi-source organic solid waste nutrient soil according to claim 9 in the field of green recycling of waste, specifically used for improving compacted and acidified soil, and increasing soil organic matter content and microbial activity.

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