A biological drying treatment method for biogas residue with high moisture content

Abstract

This invention relates to a method for biological drying of biogas residue with high moisture content, specifically including the following steps: (1) Inoculating 1-5% of Bacillus thermophilus seed liquid into LB medium and aerobically culturing at 40-60℃ for 24-48h to obtain Bacillus thermophilus bacterial liquid; (2) Adding 0.1-5% of Bacillus thermophilus bacterial liquid to biogas residue with a moisture content of not less than 80%, and mixing evenly to obtain a biological drying substrate; (3) Adding the biological drying substrate prepared in step (2) into a biological drying reactor, and drying at 40-60℃ for 7-15d to obtain organic fertilizer. The method of this invention can be used to treat biogas residue with high moisture content (greater than 80%), without the need to add auxiliary materials to adjust the carbon-nitrogen ratio. By adding microbial agents, the diversity of the mixed bacterial community in the substrate is changed, shortening the treatment time and reducing the energy consumption of the treatment process. The prepared organic fertilizer has low moisture content, high seed germination index, and good decomposition effect.

Description

Technical Field

[0001] This invention relates to the field of solid waste disposal and resource utilization technology, and in particular to a biological drying method for biogas residue with high moisture content. Background Technology

[0002] With rapid economic growth and rising living standards, urbanization and industrialization have led to an excessive increase in human demand for energy, thereby increasing the production of solid waste worldwide. Anaerobic digestion technology has significant advantages in waste recycling, clean energy production, and pollutant reduction, and has become the mainstream technology for treating municipal and agricultural solid waste in recent years.

[0003] However, with the expansion of anaerobic digestion plants, a large amount of digestion residue—biogas sludge—is generated. Biogas sludge mainly consists of undecomposed organic waste and newly generated microbial cells, often accompanied by a foul odor, and contains pathogens, plant toxins, and excessive heavy metals, causing serious environmental problems. Due to its high water content, incineration of biogas sludge consumes heat, leading to high costs; landfilling results in leachate leaching, polluting groundwater; and its use as animal feed may lead to bioaccumulation in the food chain, threatening food safety. Potential antibiotic resistance genes can also seriously impact the environment and endanger public health.

[0004] Biological drying is a technology that uses microorganisms to aerobically decompose degradable organic matter in biogas residue. The biological metabolic process generates a large amount of heat, which promotes the evaporation of moisture from the biogas residue and can shorten the dehydration time. However, if the biogas residue has a high moisture content, mechanical dehydration or the addition of auxiliary materials is required to adjust the moisture content. Leachate will also be generated after drying, which increases the complexity of subsequent processing. Moreover, the quality of the resulting fertilizer is poor, making it unsuitable for large-scale biogas residue treatment. Summary of the Invention

[0005] The purpose of this invention is to provide a method for the biological drying of biogas residue with high moisture content, which specifically includes the following steps:

[0006] (1) Inoculate the Bacillus thermophilus seed culture solution into LB medium at an inoculation rate of 1-5% and culture aerobically at 40-60℃ for 24-48h to obtain Bacillus thermophilus bacterial solution;

[0007] (2) Add 0.1-5% of thermophilic Bacillus spp. solution to biogas residue with a moisture content of not less than 80%, and mix evenly to obtain a biological drying matrix;

[0008] (3) Add the bio-drying substrate prepared in step (2) into the bio-drying reactor and dry it at a temperature of 40-60℃ for 7-15 days to obtain organic fertilizer.

[0009] In a preferred embodiment of the present invention, the thermophilic Bacillus includes any one or a combination of FJAT-43651, NJRC-14, and ATCC7953.

[0010] In a preferred embodiment of the present invention, the preparation process of the thermophilic Bacillus seed culture medium is as follows: after activating the refrigerated thermophilic Bacillus, inoculate it into LB medium at an inoculation rate of 5-10%, and culture it aerobically at 40-60℃ for 24-48 hours to obtain the culture medium.

[0011] In a preferred embodiment of the present invention, the LB culture medium comprises: 1L of deionized water, 10.0-20.0g of tryptone, 5.0-10.0g of yeast extract, 10.0-20.0g of NaCl, and pH 7.0±0.5.

[0012] In a preferred embodiment of the present invention, the LB culture medium comprises: 10.0g tryptone, 5.0g yeast extract, 10.0g NaCl, 1L deionized water, and pH 7.0±0.5.

[0013] In a preferred embodiment of the present invention, in step (1), the inoculation amount of the Bacillus thermophilus seed culture medium is 2-4%.

[0014] In the preferred embodiment of the present invention, in step (2), while adding the thermophilic Bacillus cereus bacterial solution, an organic fertilizer fermentation agent of 0.1-1% of the weight of the biogas residue is also added, preferably an organic fertilizer fermentation agent of 0.3-0.5% of the weight of the biogas residue is added.

[0015] In a preferred embodiment of the present invention, the organic fertilizer fermentation agent is any one or a combination of bacteria, fungi, actinomycetes, and yeast.

[0016] In a preferred embodiment of the present invention, the organic fertilizer fermentation agent is an organic waste fermentation starter purchased from Beijing Jingpuyuan Bioengineering Co., Ltd.

[0017] In a preferred embodiment of the present invention, the biogas residue does not need to be sterilized.

[0018] In a preferred embodiment of the present invention, the biogas residue is the residue after anaerobic digestion of organic waste.

[0019] In a preferred embodiment of the present invention, the moisture content of the biogas residue is not less than 85%, preferably not less than 90%, and more preferably not less than 95%.

[0020] In a preferred embodiment of the present invention, the pH of the biogas residue is 7-9, preferably 7.5-8.5.

[0021] In a preferred embodiment of the present invention, the total solids content of the biogas residue is 1-20%, preferably 5-15%.

[0022] In a preferred embodiment of the present invention, the carbon content of the biogas residue is 25-45%, preferably 30-40%.

[0023] In a preferred embodiment of the present invention, the nitrogen content of the biogas residue is 25-45%, preferably 30-40%.

[0024] In a preferred embodiment of the present invention, the electrical conductivity of the biogas residue is 1-5 ms / cm, preferably 2-3 ms / cm.

[0025] In a preferred embodiment of the present invention, in step (2), the amount of Bacillus thermophilus bacterial solution added is 0.1-5%, preferably 1-2%.

[0026] In a preferred embodiment of the present invention, in step (3), the drying is carried out under aeration at a rate of 0.6-2.0 L·min. -1 ·kg -1 The preferred bio-drying substrate is 0.8-1.0 L·min. -1 ·kg -1 Biological drying substrate.

[0027] In a preferred embodiment of the present invention, the aeration method is continuous aeration or intermittent aeration.

[0028] In a preferred embodiment of the present invention, the intermittent aeration is 15 min aeration followed by 15 min interval, 10 min aeration followed by 20 min interval, or 20 min aeration followed by 10 min interval.

[0029] In a preferred embodiment of the present invention, the heating temperature in step (3) is 45-50℃.

[0030] In a preferred embodiment of the present invention, the biological drying process requires turning the compost pile 1-3 times a day, using either mechanical stirring or manual turning.

[0031] In a preferred embodiment of the present invention, the organic fertilizer has a moisture content of less than 30%, preferably less than 20%, and more preferably less than 10%.

[0032] In a preferred embodiment of the present invention, the seed germination index of the organic fertilizer is higher than 70%, preferably higher than 80%, and more preferably higher than 90%.

[0033] In a preferred embodiment of the present invention, the ammonia nitrogen content of the organic fertilizer is less than 1000 mg / kg, preferably less than 500 mg / kg, and more preferably less than 300 mg / kg.

[0034] In a preferred embodiment of the present invention, the nitrate nitrogen content of the organic fertilizer is less than 1000 mg / kg, preferably less than 500 mg / kg, and more preferably less than 350 mg / kg.

[0035] In a preferred embodiment of the present invention, the humic acid content of the organic fertilizer is not less than 50 mg / g, preferably not less than 80 mg / g, and more preferably not less than 100 mg / g.

[0036] In a preferred embodiment of the present invention, the fulvic acid content of the organic fertilizer is not less than 10 mg / g, preferably not less than 20 mg / g, and more preferably not less than 40 mg / g.

[0037] Another objective of this invention is to provide an organic fertilizer prepared by a bio-drying method for biogas residue with high moisture content.

[0038] In a preferred embodiment of the present invention, the organic fertilizer has a moisture content of less than 30%, preferably less than 20%, and more preferably less than 10%.

[0039] In a preferred embodiment of the present invention, the seed germination index of the organic fertilizer is higher than 70%, preferably higher than 80%, and more preferably higher than 90%.

[0040] In a preferred embodiment of the present invention, the ammonia nitrogen content of the organic fertilizer is less than 1000 mg / kg, preferably less than 500 mg / kg, and more preferably less than 300 mg / kg.

[0041] In a preferred embodiment of the present invention, the nitrate nitrogen content of the organic fertilizer is less than 1000 mg / kg, preferably less than 500 mg / kg, and more preferably less than 350 mg / kg.

[0042] In a preferred embodiment of the present invention, the humic acid content of the organic fertilizer is not less than 50 mg / g, preferably not less than 80 mg / g, and more preferably not less than 100 mg / g.

[0043] In a preferred embodiment of the present invention, the fulvic acid content of the organic fertilizer is not less than 10 mg / g, preferably not less than 20 mg / g, and more preferably not less than 40 mg / g.

[0044] Another objective of this invention is to provide a bio-drying reactor for a high-moisture-content biogas residue bio-drying method, comprising an aeration unit, a temperature feedback and control unit, a bio-drying reactor unit, and an air outlet unit.

[0045] In a preferred embodiment of the present invention, the aeration unit includes an air pump 1, an air pipe 2, a flow regulator 3, a flow regulating valve 4, an air inlet pipe 5, an air inlet 6, and a porous aeration head 9.

[0046] In a preferred embodiment of the present invention, the temperature feedback and control unit includes a temperature control 10, a temperature display screen 11, a temperature control knob 12, a temperature feedback 13, and a real-time temperature probe 15.

[0047] In a preferred embodiment of the present invention, the bio-drying reactor unit includes a bio-drying container 7 and an insulation layer 8.

[0048] In a preferred embodiment of the present invention, the gas outlet unit includes a gas outlet 14, a gas outlet pipe 16, a gas collector 17, a gas detector 18, and a gas absorption bottle 19.

[0049] In a preferred embodiment of the present invention, the bio-drying reactor does not include a leachate treatment device.

[0050] Another objective of this invention is to provide an application of organic fertilizer prepared by a high-moisture-content biogas residue biological drying method in crop cultivation.

[0051] Unless otherwise stated, when this invention relates to percentages between liquids, the percentage is volume / volume percentage; when this invention relates to percentages between liquids and solids, the percentage is volume / weight percentage; when this invention relates to percentages between solids and liquids, the percentage is weight / volume percentage; the remainder is weight / weight percentage.

[0052] Unless otherwise stated, the present invention uses the following detection method to determine substances in feed:

[0053] 1. Moisture content: Measured in accordance with the requirements of GB / T 8576.

[0054] 2. Seed germination index: In accordance with the requirements of NY / T 525-2021, radish seeds (uncoated) were selected for measurement.

[0055] 3. Ammonia nitrogen: The potassium chloride extraction-indophenol blue method was used for determination. The aerobic fermentation sample was extracted with 1 mol / L KCl solution at a liquid-to-solid ratio of 10:1 (volume:mass). The sample was shaken at 100 rpm for 1 hour at room temperature, followed by centrifugation at 3000 rpm. The supernatant was filtered through a 0.45 μm filter membrane and set aside. 10 mL of the filtered supernatant was placed in a 100 mL stoppered colorimetric tube, and 40 mL of sodium nitroprusside-phenol colorimetric reagent was added. After thorough mixing, the mixture was allowed to stand for 15 minutes. Then, 1.00 mL of sodium dichloroisocyanurate colorimetric reagent was added and thoroughly mixed. After standing at room temperature for at least 5 hours, the absorbance at 630 nm was measured using a UV spectrophotometer (with water as a reference). The measured absorbance value was input into a pre-prepared calibration curve, and the ammonia nitrogen concentration was calculated based on the dilution factor.

[0056] 4. Nitrate Nitrogen: Using the dual-wavelength subtraction method, take 5 mL of the clear solution obtained from the ammonia nitrogen determination above and place it in a 50 mL colorimetric tube. Add 45 mL of deionized water and mix well. Then add 1 mL of 1 mol / L hydrochloric acid solution and 0.1 mL of 0.8% sulfamic acid solution. Mix thoroughly and then use a UV spectrophotometer to detect the absorbance values ​​at 220 nm and 275 nm wavelengths (using 1 mL of 1 mol / L hydrochloric acid and 50 mL of deionized water mixture as a reference). Subtract twice the absorbance value at 275 nm from the absorbance value at 220 nm to obtain the absorbance correction value of the sample. Substitute this value into the pre-prepared calibration curve and calculate the nitrate nitrogen concentration based on the dilution factor.

[0057] 5. Humic acid: The sample was extracted with a mixed solution of 0.1 mol / L NaOH and 0.1 mol / L Na₂P₂O₇ (pH = 13) at a liquid-to-solid ratio of 10:1 (volume:mass). After shaking at 150 rpm for 12 hours at room temperature, the supernatant was obtained by centrifugation at 4000 rpm. The filter residue was subjected to the same extraction, shaking, centrifugation, and supernatant collection process once. After the two filtrates were mixed thoroughly, a portion of the sample solution was diluted and the humic acid concentration was measured using a TOC analyzer.

[0058] 6. Fulvic acid: The sample was extracted with a mixed solution of 0.1 mol / L NaOH and 0.1 mol / L Na₂P₂O₇ (pH = 13) at a liquid-to-solid ratio of 10:1 (volume:mass). After shaking at 150 rpm for 12 hours at room temperature, the supernatant was obtained by centrifugation at 4000 rpm. The filter residue was subjected to the same extraction, shaking, centrifugation, and supernatant collection process once. After the two filtrates were thoroughly mixed, a portion of the sample solution was diluted and the humic acid concentration was measured using a TOC analyzer. The remaining portion was acidified with 6 mol / L hydrochloric acid to a pH below 1.5 (measured using pH paper), stirred thoroughly, and allowed to stand overnight at room temperature. The acidified and precipitated sample solution was centrifuged at 4000 rpm. The supernatant contained fulvic acid. The supernatant was completely poured off, diluted to a final volume, and the fulvic acid content was determined using a TOC analyzer.

[0059] 7. Three-dimensional fluorescence spectroscopy: Aerobic fermentation samples were extracted with deionized water at a solid-liquid ratio of 1:10 (mass:volume). After shaking at 150 rpm for 24 h, the samples were centrifuged at 4000 rpm. The supernatant was filtered through a 0.45 μm organic microporous membrane and diluted 10-50 times with deionized water. The DOC concentration in the liquid was then measured using a TOC analyzer. The remaining supernatant after DOC measurement was diluted to a DOC concentration of 10 mg / L and then scanned using a Hitachi FL-2700 microscope. The scanning parameters were: λEx = 220-600 nm, Scan interval = 5 nm; λEm = 220-600 nm, Scan interval = 10 nm. The Scan speed was 12000 nm / min. All results were subtracted from the three-dimensional fluorescence spectra of deionized water filtered through a 0.45 μm membrane under the same conditions.

[0060] 8. Microbial Diversity: Genomic DNA extraction was completed, and the extracted genomic DNA was detected by 1% agarose gel electrophoresis. Specific primers with barcodes were synthesized according to the specified sequencing regions. PCR products from the same sample were mixed and detected by 2% agarose gel electrophoresis. PCR products were recovered by gel cutting using the AxyPrep DNA Gel Recovery Kit (AXYGEN), eluted with Tris-HCl, and detected by 2% agarose gel electrophoresis. Based on the preliminary quantification results from electrophoresis, the PCR products were analyzed using QuantiFluor... TM The quantification was performed using the ST blue fluorescence quantitative system (Promega), followed by mixing in appropriate proportions according to the sequencing volume requirements for each sample. A MiSeq library was then constructed and MiSeq sequencing was performed.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] (1) The biological drying method of the present invention can be used to treat biogas residue with high water content (greater than 80%) by adding thermophilic Bacillus. It can change the composition diversity of mixed microbial community in the substrate without adding auxiliary materials to adjust the carbon-nitrogen ratio, shorten the biological drying treatment time, and reduce the energy consumption of the treatment process.

[0063] (2) The organic fertilizer prepared by this invention has low moisture content, high seed germination index, good decomposition effect, meets the organic fertilizer standard, can be reused for crop planting, is safe and effective, has no environmental risk, and realizes the resource utilization of waste.

[0064] (3) The reactor used in this invention does not require a leachate treatment device. It utilizes the heat from biological drying in conjunction with ventilation and auxiliary heating to achieve the evaporation of leachate, which simplifies the biological drying and harmless treatment process, while saving floor space and reducing treatment costs. Attached Figure Description

[0065] Figure 1 A schematic diagram of a biological drying reactor device includes an air pump 1, an air inlet pipe 2, a flow regulator 3, a flow regulating valve 4, an air inlet pipe 5, an air inlet 6, a biological drying container 7, an insulation layer 8, a porous aeration head 9, a temperature control 10, a temperature adjustment display screen 11, a temperature adjustment knob 12, a temperature feedback 13, an air outlet 14, a real-time temperature probe 15, an air outlet pipe 16, a gas collector 17, a gas detector 18, and a gas absorption bottle 19.

[0066] Figure 2 Graphs showing the changes in moisture content during the biological drying process in Examples 1-3 and Comparative Examples 1-3;

[0067] Figure 3 Graphs showing the changes in seed germination index during the bio-drying process in Examples 1-3 and Comparative Examples 1-3;

[0068] Figure 4 Graphs showing the changes in humic acid concentration during the bio-drying process in Example 2 and Comparative Example 1;

[0069] Figure 5 Three-dimensional fluorescence images of bio-dried humic acid in Example 2 and Comparative Example 1;

[0070] Figure 6 Graphs showing the changes in fulvic acid concentration during the bio-drying process in Example 2 and Comparative Example 1;

[0071] Figure 7 Example 2: Ammonia nitrogen concentration change during the biological drying process;

[0072] Figure 8 Example 2: Graph showing the change in nitrate concentration during the biological drying process;

[0073] Figure 9 Example 2: pH change diagram during the biological drying process;

[0074] Figure 10 Example 2: Graph showing the change in conductivity during the biological drying process. Detailed Implementation

[0075] The present invention will be further described below with reference to the embodiments.

[0076] In this study, the biogas residue was collected from a waste treatment plant in Beijing and was obtained by treating kitchen waste using wet anaerobic digestion. The properties of the biogas residue are shown in Table 1.

[0077] Table 1

[0078]

[0079]

[0080] The thermophilic Bacillus was commercially purchased Geobacillus thermoleovorans FJAT-43651.

[0081] The organic fertilizer fermentation agent was organic waste fermentation starter (organic fertilizer fermentation agent I) purchased from Beijing Jingpuyuan Bioengineering Co., Ltd., registration certificate number: Microbial Fertilizer (2001) Approval No. (0114), standard number: Q / TXJPY003-2000.

[0082] The LB medium consists of: 10.0 g tryptone, 5.0 g yeast extract, and 10.0 g NaCl per liter of deionized water, and the pH is adjusted to 7.0 ± 0.5.

[0083] For details on the bio-drying reactor, please refer to [link / reference]. Figure 1 The system includes an aeration unit, a temperature feedback and control unit, a bio-drying reactor unit, and an exhaust unit. The aeration unit includes an air pump 1, an air pipe 2, a flow regulator 3, a flow control valve 4, an air inlet pipe 5, an air inlet 6, and a porous aeration head 9. The temperature feedback and control unit includes a temperature controller 10, a temperature display screen 11, a temperature control knob 12, a temperature feedback mechanism 13, and a real-time temperature probe 15. The bio-drying reactor unit includes a bio-drying container 7 and an insulation layer 8. The exhaust unit includes an exhaust port 14, an exhaust pipe 16, a gas collector 17, a gas detector 18, and a gas absorption bottle 19. The bio-drying reactor does not include a leachate treatment device.

[0084] Example 1

[0085] (1) After activating the refrigerated Bacillus thermophilus, inoculate it into a culture flask containing LB medium at an inoculation rate of 5% and culture it at 60°C for 48 hours to obtain seed culture solution; take 1 ml of seed culture solution and inoculate it into a new culture flask, add 20 ml of LB medium, and culture it aerobically at 60°C for 48 hours to obtain Bacillus thermophilus bacterial solution.

[0086] (2) Take the thermophilic Bacillus cereus bacterial solution prepared in step (1) and add it to 1L of unsterilized biogas residue. Stir and mix evenly to obtain a biological drying matrix.

[0087] (3) The bio-drying substrate is added to the bio-drying reactor, and the substrate is manually turned over once a day. Continuous aeration is performed using a blower at an aeration rate of 0.8 L·min. -1 ·kg -1 Organic fertilizer is obtained by biological drying at 50℃ for 12 days.

[0088] Example 2

[0089] (1) After activating the refrigerated Bacillus thermophilus, inoculate it into a culture flask containing LB medium at an inoculation rate of 5% and culture it at 60°C for 48 hours to obtain seed culture solution; take 1 ml of seed culture solution and inoculate it into a new culture flask, add 20 ml of LB medium, and culture it aerobically at 60°C for 48 hours to obtain Bacillus thermophilus bacterial solution.

[0090] (2) Take the thermophilic Bacillus cereus bacterial solution prepared in step (1) and 5g of commercially available organic fertilizer fermentation agent, add them together to 1L of unsterilized biogas residue, stir and mix evenly to obtain a biological drying substrate;

[0091] (3) The bio-drying substrate is added to the bio-drying reactor, and the substrate is manually turned over once a day. Continuous aeration is performed using a blower at an aeration rate of 0.8 L·min. -1 ·kg -1 Organic fertilizer is obtained by biological drying at 50℃ for 12 days.

[0092] Example 3

[0093] (1) After activating the refrigerated Bacillus thermophilus, inoculate it into a culture flask containing LB medium at an inoculation rate of 5% and culture it at 60°C for 48 hours to obtain seed culture solution; take 1 ml of seed culture solution and inoculate it into a new culture flask, add 20 ml of LB medium, and culture it aerobically at 60°C for 48 hours to obtain Bacillus thermophilus bacterial solution.

[0094] (2) Take the thermophilic Bacillus cereus bacterial solution prepared in step (1) and 5g of commercially available organic fertilizer fermentation agent, add them together to 1L of unsterilized biogas residue, stir and mix evenly to obtain a biological drying substrate;

[0095] (3) The bio-drying substrate is added to the bio-drying reactor, and the substrate is manually turned over once a day. Intermittent aeration is performed using a blower at an aeration rate of 0.8 L·min. -1 ·kg -1 The aeration frequencies were 15 min aeration followed by 15 min intermittent aeration, 10 min aeration followed by 20 min intermittent aeration, and 20 min aeration followed by 10 min intermittent aeration. After biological drying treatment at 50℃ for 12 days, organic fertilizer was obtained.

[0096] Comparative Example 1

[0097] (1) Add 21 ml of LB medium to 1 L of unsterilized biogas residue and stir to mix evenly to obtain a bio-drying substrate;

[0098] (2) Add the bio-drying substrate to the bio-drying reactor, manually turn the substrate once a day, and use a blower for continuous aeration at an aeration rate of 0.8 L·min.-1 ·kg -1 Organic fertilizer is obtained by biological drying at 50℃ for 12 days.

[0099] Comparative Example 2

[0100] (1) Take 5g of commercially available organic fertilizer fermentation agent and add it to 1L of unsterilized biogas residue. Stir and mix evenly to obtain a biological drying substrate.

[0101] (2) The bio-drying substrate is added to the bio-drying reactor, and the substrate is manually turned over once a day. Continuous aeration is performed using a blower at an aeration rate of 0.8 L·min. -1 ·kg -1 Organic fertilizer is obtained by biological drying at 50℃ for 12 days.

[0102] Comparative Example 3

[0103] (1) Add 21 ml of LB medium to 1 L of sterilized biogas residue and stir to mix evenly to obtain a bio-drying substrate;

[0104] (2) Add the bio-drying substrate to the bio-drying reactor, manually turn the substrate once a day, and use a blower for continuous aeration at an aeration rate of 0.8 L·min. -1 ·kg -1 Organic fertilizer is obtained by biological drying at 50℃ for 12 days.

[0105] Experimental Example 1

[0106] The moisture content, seed germination index (GI), humic acid concentration, fulvic acid concentration, ammonia nitrogen concentration, nitrate nitrogen concentration, pH value, and electrical conductivity of the organic fertilizers prepared in Examples 1-3 and Comparative Examples 1-3 were measured. The results are shown in [Figure 1]. Figures 2-10 .

[0107] The above description of specific embodiments of the present invention does not limit the present invention. Those skilled in the art can make various changes or modifications based on the present invention, and as long as they do not depart from the spirit of the present invention, they should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for drying biogas residue with high moisture content, characterized in that, Specifically comprising the following steps: (1) inoculate the Bacillus stearothermophilus seed culture solution into LB culture medium at an inoculation amount of 1-5%, and cultivate aerobically at a temperature of 40-60°C for 24-48 h to obtain a Bacillus stearothermophilus bacterial solution; The preparation process of the Bacillus stearothermophilus seed culture solution is as follows: after the Bacillus stearothermophilus FJAT-43651 under cold storage is activated, inoculate it into LB culture medium at an inoculation amount of 5-10%, and cultivate aerobically at a temperature of 40-60°C for 24-48 h to obtain the Bacillus stearothermophilus seed culture solution; The LB culture medium comprises deionized water 1L, tryptone 10.0-20.0 g, yeast extract 5.0-10.0 g, NaCl 10.0-20.0 g, and pH 7.0±0.5; (2) add 0.1-5% of the Bacillus stearothermophilus bacterial solution to the biogas residue with a water content of not less than 80% by weight of the biogas residue, and mix uniformly to obtain a biological drying substrate, wherein the biogas residue is the residue after anaerobic digestion of organic waste, and the biogas residue does not need to be sterilized; At the same time of adding the Bacillus stearothermophilus bacterial solution, 0.1-1% of an organic fertilizer fermentation agent by weight of the biogas residue is also added, and the organic fertilizer fermentation agent is an organic waste fermentation fungus. (3) add the biological drying substrate prepared in step (2) into a biological drying reactor, and dry at a temperature of 40-60°C for 7-15 d to obtain the organic fertilizer, The drying is performed under aeration at an aeration rate of 0.6-2.0 L min -1 · kg -1 Bio-dried substrate; The organic fertilizer has a water content of less than 10%, a seed germination index of more than 90%, a humic acid content of not less than 100 mg / g, a fulvic acid content of not less than 40 mg / g, a nitrate nitrogen content of less than 350 mg / kg, and an ammonia nitrogen content of less than 1000 mg / kg.

2. The method of claim 1, wherein, The LB culture medium comprises tryptone 10.0 g, yeast extract 5.0 g, NaCl 10.0 g, deionized water 1L, and pH 7.0±0.

5.

3. The method of claim 1, wherein, In step (1), the inoculation amount of the Bacillus stearothermophilus seed culture solution is 2-4%.

4. The method of claim 1, wherein, In step (2), 0.3-0.5% of the organic fertilizer fermentation agent by weight of the biogas residue is added.

5. The method of claim 1, wherein, The water content of the biogas residue is not less than 85%.

6. The method of claim 5, wherein, The water content of the biogas residue is not less than 90%.

7. The method of claim 6, wherein, The water content of the biogas residue is not less than 95%.

8. The method of claim 1, wherein, The pH of the biogas residue is 7-9.

9. The method of claim 8, wherein, The pH of the biogas residue is 7.5-8.

5.

10. The method of claim 1, wherein, The total solid content of the biogas residue is 1-20%.

11. The method of claim 10, wherein, The total solid content of the biogas residue is 5-15%.

12. The method of claim 1, wherein, The conductivity of the biogas residue is 1-5 ms / cm.

13. The method of claim 12, wherein, The conductivity of the biogas residue is 2-3 ms / cm.

14. The method of claim 1, wherein, In step (2), the addition amount of the Bacillus stearothermophilus bacterial solution is 0.1-5%.

15. The method of claim 14, wherein, In step (2), the addition amount of the Bacillus stearothermophilus bacterial solution is 1-2%.

16. The method of claim 1, wherein, The aeration mode is continuous aeration or intermittent aeration.

17. The method of claim 16, wherein, The intermittent aeration is aeration for 15 min, intermittent for 15 min, aeration for 10 min, intermittent for 20 min, or aeration for 20 min, intermittent for 10 min.

18. The method of claim 1, wherein, In step (3), the temperature is 45-50°C.

19. The method of claim 1, wherein, In the biological drying process, the pile needs to be turned over 1-3 times a day, using mechanical stirring and turning over or manual turning over.

20. The method of claim 1, wherein, The ammonia nitrogen content of the organic fertilizer is less than 500 mg / kg.

21. The method of claim 20, wherein, The ammonia nitrogen content of the organic fertilizer is less than 300 mg / kg.

Images