Method for preparing crop nutrient solution from kitchen fermented biogas slurry

Abstract

The invention relates to the technical field of biogas slurry resource utilization, in particular to a method for preparing a crop nutrient solution by using kitchen fermented biogas slurry, which comprises the following steps: stirring and heating the kitchen fermented biogas slurry through a biogas slurry tank, and adjusting the pH value by using phosphoric acid to obtain a pretreatment solution; determining a treatment mode of the pretreatment liquid according to the pollution characterization value to obtain a purified liquid; cooling the purified liquid; when it is judged that the preparation of the purification liquid meets the preset standard according to the beneficial component retention rate, whether the preparation of the purification liquid meets the preset standard or not is judged secondarily according to the chromaticity deviation value; and adding a preservative into the purified liquid meeting the preset standard to obtain the crop nutrient solution. The preparation efficiency of the crop nutrient solution is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of biogas slurry resource utilization, and in particular to a method for preparing crop nutrient solution by utilizing biogas slurry fermented in kitchen. Background Art

[0002] Most of the kitchen waste is a large amount of food residue generated in people's daily life and production process. After extracting oil and separating solid matter by centrifugation, the remaining wastewater accounts for more than 80% of the entire system. After fermentation, these wastewaters produce a large amount of biogas slurry.

[0003] Fermented biogas from food waste can be used to prepare nutrient solution for crops, mainly because it is rich in macroelements such as nitrogen, phosphorus, potassium, and a variety of trace elements, and contains bioactive substances such as amino acids and plant hormones, which can promote crop growth; through anaerobic fermentation, harmful substances in food waste are inactivated, and at the same time, rapid fermentation technology improves treatment efficiency and ensures the safety of biogas.

[0004] The beneficial ingredients of crop nutrient solution prepared from food waste fermentation biogas include macroelements such as nitrogen, phosphorus, and potassium, trace elements such as calcium, iron, and zinc, as well as bioactive substances such as amino acids, vitamins, plant hormones, and antibiotics. These ingredients can promote crop growth and enhance disease resistance; at the same time, the organic matter and humic acid in the biogas slurry can improve soil structure and enhance water and fertilizer retention capacity. Among them, protein and humic acid are key monitoring indicators.

[0005] Traditional high-temperature sterilization or ozone oxidation processes can easily cause protein denaturation or humic acid decomposition due to improper parameter control, leading to the loss of active ingredients in the nutrient solution; at the same time, excessive sterilization may destroy the natural plant hormones and microbial metabolites in the biogas slurry, reducing its promoting effect on crop growth.

[0006] Chinese patent application publication number: CN109095965A discloses a biogas slurry composite nutrient solution, the components of which are, by mass percentage, 70-80% biogas slurry, 9-19% liquid ammonium phosphate, 3-8% urea, 1-5% potassium chloride, 1-5% biological bacteria, and 0.05-0.2% sodium nitrophenolate. It also provides a method for preparing the biogas slurry composite nutrient solution, comprising the following steps: (1) preparing the materials according to the above components (by mass percentage); (2) mixing and stirring: adding liquid ammonium phosphate, urea, potassium chloride, biological bacteria, and sodium nitrophenolate to the biogas slurry respectively and stirring thoroughly; (3) adjusting the pH: adding anhydrous potassium carbonate to adjust the pH to 6-7, letting it stand for 1-2 hours, and then filling it.

[0007] It can be seen that the above technical solution directly uses the original biogas slurry without mentioning the treatment of pollutants such as oil, pathogenic microorganisms, suspended matter, etc. in the biogas slurry, which affects the corruption of the nutrient solution; it does not consider the retention rate of protein and humic acid after treatment, which affects the content of protein and humic acid, resulting in unstable fertilizer efficiency of the nutrient solution, thereby leading to the problem of poor fertilizer efficiency of the nutrient solution. Summary of the Invention

[0008] To this end, the present invention provides a method for preparing crop nutrient solution using kitchen fermentation biogas slurry, so as to overcome the problems in the prior art of directly using raw biogas slurry without mentioning the treatment of pollutants such as oil, pathogenic microorganisms, suspended matter, etc. in the biogas slurry, which affects the corruption of the nutrient solution; and without considering the retention rate of protein and humic acid after treatment, which affects the content of protein and humic acid, resulting in unstable fertilizer efficiency of the nutrient solution, thereby leading to poor fertilizer efficiency of the nutrient solution.

[0009] To achieve the above object, the present invention provides a method for preparing a nutrient solution for crops using biogas slurry from kitchen fermentation, comprising: Stirring and heating food fermentation biogas slurry in a biogas slurry tank, adjusting the pH with phosphoric acid during the heating process to obtain a pretreated liquid, collecting the turbidity and total bacterial count of the pretreated liquid to obtain a pollution characteristic value of the pretreated liquid, and obtaining the area of the protein characteristic peak and the area of the humic acid characteristic peak in the infrared spectrum of the pretreated liquid; determining a treatment mode for the pre-treated liquid according to the pollution characterization value of the pre-treated liquid to obtain a purified liquid; Cooling the purified liquid, collecting the area of a protein characteristic peak and the area of a humic acid characteristic peak in an infrared spectrum of the purified liquid to obtain a beneficial component retention rate, wherein the beneficial components of the purified liquid include protein and humic acid; When it is determined that the preparation of the purified liquid meets the preset standard according to the beneficial component retention rate, a secondary determination is made as to whether the preparation of the purified liquid meets the preset standard according to the chromaticity deviation value of the purified liquid; When it is determined that the preparation of the purified liquid does not meet the preset standard based on the beneficial component retention rate, the reason why the preparation of the purified liquid does not meet the preset standard is determined based on the absorbance ratio, wherein the reasons include excessive ozone oxidation and protein destruction; A preservative is added to the purified liquid that meets the preset standards to obtain a crop nutrient solution.

[0010] Furthermore, the treatment mode of the pretreatment liquid is determined according to the pollution characterization value of the pretreatment liquid, wherein: If the pollution characterization value is less than the first preset pollution characterization value, the pretreatment liquid is sterilized at a first preset sterilization temperature and a first preset sterilization time, and then subjected to ozone oxidation treatment after standing for a preset stratification time.

[0011] Furthermore, the treatment mode of the pretreatment liquid is determined according to the pollution characterization value of the pretreatment liquid, wherein: If the pollution characterization value is greater than or equal to the first preset pollution characterization value, high-temperature sterilization is performed according to the preset sterilization temperature and sterilization time, and flotation degreasing treatment and ozone oxidation treatment are performed in sequence before filtration.

[0012] Furthermore, the process of obtaining the pollution characterization value includes: respectively obtaining the turbidity and total bacterial count of the pretreatment liquid; The ratio of the turbidity of the pre-treated liquid to the preset turbidity is recorded as the turbidity ratio; The ratio of the total number of colonies in the pre-treated solution to the preset total number of colonies is recorded as the colony ratio; Multiplying the turbidity ratio by the first weight to obtain a turbidity evaluation value; Multiplying the colony ratio by the second weight to obtain a colony evaluation value; The turbidity evaluation value and the colony evaluation value are added to obtain the pollution characterization value.

[0013] Furthermore, when the beneficial ingredient retention rate is less than a first preset retention rate, it is determined that the preparation of the purified liquid does not meet the preset standard, and the reason why the preparation of the purified liquid does not meet the preset standard is determined based on the absorbance ratio of the purified liquid; wherein the beneficial ingredient retention rate is jointly determined by the area of the protein characteristic peak and the area of the humic acid characteristic peak in the infrared spectrum of the purified liquid and the area of the protein characteristic peak and the area of the humic acid characteristic peak in the infrared spectrum of the pretreatment liquid.

[0014] Furthermore, when the beneficial component retention rate is greater than or equal to the first preset retention rate and less than the second preset retention rate, it is determined that the preparation of the purified liquid meets the preset standard, and a secondary determination is made as to whether the preparation of the purified liquid meets the preset standard based on the chromaticity deviation value of the purified liquid; The first preset retention rate is smaller than the second preset retention rate.

[0015] Further, the reason why the preparation of the purified liquid does not meet the preset standard is determined based on the absorbance ratio, wherein: If the absorbance ratio is less than a preset absorbance ratio, it is determined that the reason why the preparation of the purified liquid does not meet the preset standard is that the ozone oxidation of the pre-treated liquid is excessive; If the absorbance ratio is greater than or equal to the preset absorbance ratio, it is determined that the reason why the preparation of the purified liquid does not meet the preset standard is that the protein in the purified liquid is destroyed, and the preset sterilization temperature corresponding to the treatment mode adopted by the pretreatment liquid is reduced according to the difference between the absorbance ratio and the preset absorbance ratio; The absorbance ratio is the ratio between the ultraviolet absorbance of the protein characteristic peak and the ultraviolet absorbance of the humic acid characteristic peak of the purified liquid.

[0016] Furthermore, the reduction range of the preset sterilization temperature corresponding to the treatment mode adopted by the pretreatment liquid is positively correlated with the difference between the absorbance ratio and the preset absorbance ratio.

[0017] Furthermore, a secondary determination is made based on the chromaticity deviation value as to whether the preparation of the purification liquid meets the preset standard, wherein: If the chromaticity deviation value is less than the preset chromaticity deviation value, it is determined that the preparation of the purification liquid meets the preset standard; If the chromaticity deviation value is greater than or equal to the preset chromaticity deviation value, it is determined that the preparation of the purification liquid does not meet the preset standard, and the preset sterilization time corresponding to the treatment mode of the pretreatment liquid is reduced according to the ratio of the chromaticity deviation value to the preset chromaticity deviation value; The chromaticity deviation value is a ratio of a difference between the chromaticity of the purified liquid and a preset chromaticity to the preset chromaticity.

[0018] Furthermore, the reduction range of the preset sterilization time corresponding to the treatment mode adopted by the pretreatment liquid is positively correlated with the ratio of the chromaticity deviation value to the preset chromaticity deviation value.

[0019] Compared with the prior art, the beneficial effect of the present invention lies in that the present invention generates a pollution characterization value through the turbidity and total colony count of the pretreatment liquid to drive a differentiated treatment process, establishes a feedback evaluation mechanism based on the characteristic peak area of the infrared spectrum of the purified liquid, and balances the sterilization purification and retention of organic active ingredients in the biogas slurry treatment; utilizes the secondary judgment of chromaticity deviation and the adaptive adjustment of sterilization temperature and sterilization heating time to achieve closed-loop real-time optimization of the process of preparing nutrient solution from restaurant biogas slurry, thereby realizing efficient utilization of restaurant biogas slurry.

[0020] Furthermore, the present invention accurately divides the treatment strategy according to the pollution characterization value. When the pollution is low, only a simplified process of high-temperature sterilization and ozone oxidation is adopted to retain the active ingredients; when the pollution is medium or high, flotation oil removal, centrifugation or ultrafiltration membrane filtration are superimposed step by step to avoid redundant treatment of low-pollution biogas slurry. At the same time, the purification of highly polluted biogas slurry is enhanced to specifically remove grease, microorganisms and colloidal impurities, thereby improving the treatment efficiency of food biogas slurry.

[0021] Furthermore, when the beneficial ingredient retention rate is less than the first preset retention rate, the present invention uses the ultraviolet absorbance ratio to directly distinguish between two essential defects, excessive ozone oxidation and thermal destruction of protein, to avoid the limitation of fuzzy attribution; when the beneficial ingredient retention rate is between the first and second preset retention rates, the color deviation value is introduced for secondary verification, and the preparation effect is correlated with the color change to avoid detection errors, thereby improving the reliability of the evaluation.

[0022] Furthermore, the present invention distinguishes between excessive ozone oxidation and thermal destruction of proteins by comparing the absorbance ratio with a preset threshold, thereby improving the preparation efficiency.

[0023] Furthermore, the present invention converts the traditional experience-based color observation into an objective ratio of chromaticity to a preset value. Through secondary determination of chromaticity deviation and adaptive correction of process parameters, it adapts to the composition fluctuations of food waste liquid from different sources, thereby improving the adaptability of the preparation process.

[0024] Furthermore, the present invention achieves precise control of the reduction amplitude of the preset sterilization time by setting the reduction amplitude of the preset sterilization time corresponding to the treatment mode adopted by the pretreatment liquid to be positively correlated with the ratio of the chromaticity deviation value to the preset chromaticity deviation value. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of a method for preparing a nutrient solution for crops using biogas slurry fermented from kitchen waste according to an embodiment of the present invention; Figure 2 This is a flow chart of an embodiment of the present invention for determining whether the preparation of a purified liquid meets a preset standard based on the beneficial component retention rate; Figure 3 This is a flow chart of an embodiment of the present invention for secondary determining whether the preparation of the purification solution meets the preset standard based on the chromaticity deviation value; Figure 4 This is a flow chart for determining why the preparation of the purification solution does not meet the preset standard according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below with reference to embodiments. It should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0027] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0028] It should be pointed out that the data in this embodiment are all obtained by comprehensive analysis and evaluation of the historical test data of the present invention in the three months before this test and the corresponding historical test results. Those skilled in the art can understand that the method of determining the above-mentioned single parameter of the method of the present invention can be to select the value with the highest proportion as the preset standard parameter according to the data distribution, use weighted summation to use the obtained value as the preset standard parameter, substitute each historical data into a specific formula and use the value obtained by the formula as the preset standard parameter or other selection methods, as long as the method of the present invention can clearly define the different specific situations in the single determination process through the obtained value.

[0029] See also Figure 1 、 Figure 2 、 Figure 3 as well as Figure 4 As shown, it is a flow chart of a method for preparing crop nutrient solution using food fermentation biogas slurry according to an embodiment of the present invention; a flow chart of determining whether the preparation of purified liquid meets the preset standard according to the beneficial component retention rate according to an embodiment of the present invention; a flow chart of determining whether the preparation of the purified liquid meets the preset standard according to the chromaticity deviation value according to an embodiment of the present invention; and a flow chart of determining the reason why the preparation of the purified liquid does not meet the preset standard according to an embodiment of the present invention.

[0030] An embodiment of the present invention provides a method for preparing a nutrient solution for crops using biogas slurry fermented from kitchen waste, comprising: Step S1: stirring and heating 10 cubic meters of food fermentation biogas slurry in a 15 cubic meter biogas slurry tank, adjusting the pH of the slurry using phosphoric acid before the temperature is raised to a preset temperature of 70°C to obtain a pretreated liquid, collecting the turbidity and total bacterial count of the pretreated liquid to obtain a pollution characteristic value of the pretreated liquid, and obtaining the area of the protein characteristic peak and the area of the humic acid characteristic peak of the infrared spectrum of the pretreated liquid; wherein the pH value is adjusted to 5-6; Step S2, determining a treatment mode for the pre-treated liquid according to the contamination characterization value of the pre-treated liquid to obtain a purified liquid; Step S3, cooling the purified liquid to 60° C., collecting the areas of the protein characteristic peak and the humic acid characteristic peak of the infrared spectrum of the purified liquid to obtain a beneficial component retention rate, wherein the beneficial components of the purified liquid include protein and humic acid; Step S4, when it is determined that the preparation of the purified liquid meets the preset standard based on the beneficial component retention rate, a secondary determination is made based on the chromaticity deviation value of the purified liquid whether the preparation of the purified liquid meets the preset standard; Step S5, when it is determined that the preparation of the purified liquid does not meet the preset standard based on the beneficial component retention rate, the reason why the preparation of the purified liquid does not meet the preset standard is determined based on the absorbance ratio, wherein the reasons include excessive ozone oxidation and protein destruction; Step S6, adding a preservative to the purified liquid that meets the preset standard to obtain a crop nutrient solution.

[0031] Specifically, the preservative is 0.1% potassium sorbate.

[0032] Specifically, the crop nutrient solution contains the following components in mass percentage: 95.05%-95.95% water, 1.3%-1.7% macroelements, the macroelements include 0.5%-0.6% total nitrogen, 0.3%-0.4% phosphorus pentoxide, and 0.5%-0.7% potassium oxide; 0.3%-0.5% secondary elements, the secondary elements include 0.15%-0.25% calcium, 0.08%-0.15% magnesium, and 0.07%-0.10% sulfur; 1.5%-1.9% humus, of which water-soluble humic acid is greater than or equal to 1.2%; 0.3%-0.4% total trace elements, the trace elements are selected from at least three of iron, manganese, zinc, copper, boron, and molybdenum; 0.1%-0.2% protein, and 0.05%-0.15% preservatives.

[0033] Specifically, the treatment mode of the pretreatment liquid is determined according to the pollution characterization value of the pretreatment liquid, wherein: If the pollution characterization value is less than the first preset pollution characterization value of 0.85, determining to adopt the first processing mode; If the pollution characterization value is greater than or equal to the first preset pollution characterization value and less than the second preset pollution characterization value of 1.75, then determining to adopt the second processing mode; If the pollution characterization value is greater than or equal to the second preset pollution characterization value, it is determined to adopt the third processing mode.

[0034] Specifically, when the pretreatment liquid adopts the first treatment mode, the pretreatment liquid is sterilized at a first preset sterilization temperature of 85° C. and a first preset sterilization time of 60 min, and then subjected to ozone oxidation treatment after standing for a preset stratification time of 120 min, with an ozone dosage of 15 mg / L and a reaction time of 30 min; When the pretreatment liquid adopts the second treatment mode, the pretreatment liquid is sterilized at a first preset sterilization temperature and a second preset sterilization time of 80 minutes, and is sequentially subjected to flotation deoiling treatment and ozone oxidation treatment, followed by centrifugal filtration, wherein the air-water ratio in the flotation deoiling treatment is 1:30, and the treatment time is 40 minutes; the ozone dosage in the ozone oxidation treatment is 15 mg / L, and the reaction time is 30 minutes; the rotation speed in the centrifugal filtration is 3000 rpm, and the centrifugation time is 20 minutes.

[0035] The pretreatment liquid adopts the third treatment mode, and the pretreatment liquid is high-temperature sterilized at a second preset sterilization temperature of 100°C and a first preset sterilization time, and is sequentially subjected to flotation deoiling treatment and ozone oxidation treatment, and then ultrafiltration membrane filtration, wherein the air-water ratio in the flotation deoiling treatment is 1:40, and the treatment time is 60 minutes; the ozone dosage in the ozone oxidation treatment is 15 mg / L, and the reaction time is 30 minutes; the molecular weight cutoff in the ultrafiltration membrane filtration is 200Da.

[0036] The first preset sterilization temperature is lower than the second preset sterilization temperature, and the first preset sterilization time is lower than the second preset sterilization time.

[0037] Specifically, when the contamination characterization value is less than the first preset contamination characterization value, it means that the contaminants are few and easy to treat, and the basic treatment, i.e., the first treatment mode, is selected to perform sterilization and oxidation; When the pollution characterization value is between the first preset pollution characterization value and the second preset pollution characterization value, the pollutant concentration increases and the composition is more complex, including grease, colloids or suspended solids. Sterilization and oxidation alone are not enough to effectively remove these substances. Grease will wrap microorganisms and reduce sterilization efficiency, and colloids or suspended solids will interfere with the oxidation reaction. Therefore, the introduction of flotation degreasing and centrifugal filtration is a necessary option. The treatment intensity of the second treatment mode is between the first and third treatment modes; When the contamination characteristic value exceeds the second preset contamination characteristic value, the pollutant concentration is extremely high, and the components include a large amount of difficult-to-degrade organic matter, soluble small molecules, oils, colloids, and microorganisms. This requires a more stringent treatment combination: higher temperature sterilization, more thorough flotation degreasing, ozone oxidation, and an ultrafiltration membrane that can intercept small soluble organic molecules. This mode has the best treatment effect, but also the highest energy consumption, time, and cost. In this case, using the first or second treatment mode will not meet the treatment requirements.

[0038] Specifically, the pollution characterization value is calculated by the following formula:

[0039] Where W represents the pollution characterization value; α represents the first weight, which is set to 0.6; β represents the second weight, which is set to 0.4; T1 represents the turbidity of the pretreatment liquid; T0 represents the preset turbidity, which is set to 50 NTU; N1 represents the total number of colonies in the pretreatment liquid; N0 represents the preset total number of colonies, which is set to 1×10 3 CFU / mL.

[0040] Specifically, whether the preparation of the purified liquid meets the preset standard is determined based on the beneficial component retention rate of the purified liquid, wherein: If the beneficial component retention rate is less than 80% of the first preset retention rate, it is determined that the preparation of the purified liquid does not meet the preset standard, and the reason why the preparation of the purified liquid does not meet the preset standard is determined based on the absorbance ratio of the purified liquid; If the beneficial ingredient retention rate is greater than or equal to the first preset retention rate and less than 95% of the second preset retention rate, it is determined that the preparation of the purified liquid meets the preset standard, and a secondary determination is made based on the chromaticity deviation value of the purified liquid whether the preparation of the purified liquid meets the preset standard; If the beneficial component retention rate is greater than or equal to the second preset retention rate, it is determined that the preparation of the purified liquid meets the preset standard.

[0041] In this embodiment, the value range of the first preset retention rate is (60%, 85%), and the value range of the second preset retention rate is (90%, 99%). Preferably, the first preset retention rate is selected as 80%, and the second preset retention rate is selected as 95%.

[0042] Specifically, when the retention rate is less than 80%, it indicates severe protein or humic acid loss, and the cause of the defect can be directly determined by the absorbance ratio. When the retention rate is between 80% and 95%, the component loss is relatively minor, but the color may exceed the standard due to residual colloids or undecomposed organic matter. In this case, the color deviation value is used for secondary determination. When the retention rate is greater than or equal to 95%, the component retention is sufficient and the process is stable, and it can be directly determined to meet the standard.

[0043] Specifically, the process of obtaining the beneficial ingredient retention rate includes: Obtaining the area of the protein characteristic peak and the area of the humic acid characteristic peak in the infrared spectrum of the pretreatment liquid; Obtaining the area of the protein characteristic peak and the area of the humic acid characteristic peak in the infrared spectrum of the purified liquid; The ratio of the area of the protein characteristic peak in the infrared spectrum of the purified liquid to the area of the protein characteristic peak in the infrared spectrum of the pretreated liquid is recorded as the protein retention rate, and the protein retention rate is multiplied by the protein weight to obtain a first evaluation value; The ratio of the area of the humic acid characteristic peak in the infrared spectrum of the purified liquid to the area of the humic acid characteristic peak in the infrared spectrum of the pretreated liquid is recorded as the humic acid retention rate, and the humic acid retention rate is multiplied by the humic acid weight to obtain a second evaluation value; The beneficial component retention rate is the sum of the first evaluation value and the second evaluation value.

[0044] Specifically, the reason why the preparation of the purified liquid does not meet the preset standard is determined based on the absorbance ratio, wherein: If the absorbance ratio is less than a preset absorbance ratio of 0.80, it is determined that the reason why the preparation of the purified liquid does not meet the preset standard is that the ozone oxidation of the pre-treated liquid is excessive; If the absorbance ratio is greater than or equal to the preset absorbance ratio, it is determined that the reason why the preparation of the purified liquid does not meet the preset standard is that the protein in the purified liquid is destroyed, and the preset sterilization temperature corresponding to the treatment mode adopted by the pretreatment liquid is reduced according to the difference between the absorbance ratio and the preset absorbance ratio; The absorbance ratio is the ratio between the ultraviolet absorbance of the protein characteristic peak and the ultraviolet absorbance of the humic acid characteristic peak of the purified liquid, wherein the absorbance at a wavelength of 280 nm is measured using an ultraviolet spectrophotometer and recorded as the ultraviolet absorbance of the protein characteristic peak, and the absorbance at a wavelength of 254 nm is measured using an ultraviolet spectrophotometer and recorded as the ultraviolet absorbance of the humic acid characteristic peak.

[0045] In this embodiment, the preset absorbance ratio is selected as 0.80, but the above value is not limited thereto, and those skilled in the art can also adjust the value according to actual needs.

[0046] Specifically, the reduction amplitude of the preset sterilization temperature corresponding to the treatment mode adopted by the pretreatment liquid is positively correlated with the difference between the absorbance ratio and the preset absorbance ratio, wherein the positive correlation is, for example, a linear positive correlation or a nonlinear positive correlation, and the linear slope of the linear positive correlation is not specifically limited. It can be understood that the greater the difference between the absorbance ratio and the preset absorbance ratio, the greater the reduction amplitude of the preset sterilization temperature corresponding to the treatment mode adopted by the pretreatment liquid.

[0047] Specifically, the chromaticity deviation value is used to determine whether the preparation of the purification liquid meets the preset standard. If the chromaticity deviation value is less than the preset chromaticity deviation value of 0.31, it is determined that the preparation of the purified liquid meets the preset standard; If the chromaticity deviation value is greater than or equal to the preset chromaticity deviation value, it is determined that the preparation of the purification liquid does not meet the preset standard, and the preset sterilization time corresponding to the treatment mode of the pretreatment liquid is reduced according to the ratio of the chromaticity deviation value to the preset chromaticity deviation value; The chromaticity deviation value is a ratio of a difference between the chromaticity of the purified liquid and a preset chromaticity 115Pt-Co to the preset chromaticity 115Pt-Co, wherein the chromaticity of the purified liquid is measured by a portable colorimeter.

[0048] In this embodiment, the preset chromaticity deviation value is selected as 0.31, but the above value is not limited thereto, and those skilled in the art may also adjust the value according to actual needs.

[0049] Specifically, chromaticity directly reflects the concentration of dissolved organic matter, colloidal substances and chromophores in the liquid. The removal of impurities such as oil, suspended matter, etc. will reduce the chromaticity of the liquid. However, improper treatment will lead to protein denaturation and humic acid degradation, which will increase the chromaticity.

[0050] Specifically, the reduction in the preset sterilization time corresponding to the treatment mode adopted by the pretreatment liquid is positively correlated with the ratio of the chromaticity deviation value to the preset chromaticity deviation value, wherein the positive correlation is, for example, a linear positive correlation or a nonlinear positive correlation, and the linear slope of the linear positive correlation is not specifically limited. It can be understood that the greater the ratio of the chromaticity deviation value to the preset chromaticity deviation value, the greater the reduction in the preset sterilization time corresponding to the treatment mode adopted by the pretreatment liquid.

[0051] Comparative experiment: wheat sowing experiment using the crop nutrient solution prepared by the present invention: Blank control group: irrigation water; ordinary nutrient solution group: commercially available conventional crop nutrient solution; nutrient solution group: nutrient solution prepared according to the invention method; Each group selected 150 wheat seeds of uniform size and irrigated them twice a week at 500 mL / m 2 The concentration of the nutrient solution was diluted to an EC value of 1.2mS / cm, the temperature was kept at 25℃±2℃, the humidity was 60%±5%, and the sunlight was natural. The germination rate of wheat was counted 5 days after sowing. The statistical results are shown in Table 1 below: Table 1 Relationship between wheat germination rate 5 days after sowing and different irrigation treatments

[0052] This table shows that the germination rate of the nutrient solution group of the present invention is higher than that of the blank control group and the ordinary nutrient solution group, indicating that the core growth-promoting components of the nutrient solution such as protein and humic acid are retained by dynamically grading the pollution characterization values of the biogas slurry and real-time monitoring of infrared spectroscopy, optimizing parameters such as sterilization temperature and ozone oxidation intensity.

[0053] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

[0054] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing crop nutrient solution using food fermentation biogas slurry, characterized in that: include: Stirring and heating food fermentation biogas slurry in a biogas slurry tank, adjusting the pH with phosphoric acid during the heating process to obtain a pretreated liquid, collecting the turbidity and total bacterial count of the pretreated liquid to obtain a pollution characteristic value of the pretreated liquid, and obtaining the area of the protein characteristic peak and the area of the humic acid characteristic peak in the infrared spectrum of the pretreated liquid; determining a treatment mode for the pre-treated liquid according to the pollution characterization value of the pre-treated liquid to obtain a purified liquid; Cooling the purified liquid, collecting the area of a protein characteristic peak and the area of a humic acid characteristic peak in an infrared spectrum of the purified liquid to obtain a beneficial component retention rate, wherein the beneficial components of the purified liquid include protein and humic acid; When it is determined that the preparation of the purified liquid meets the preset standard according to the beneficial component retention rate, a secondary determination is made as to whether the preparation of the purified liquid meets the preset standard according to the chromaticity deviation value of the purified liquid; When it is determined that the preparation of the purified liquid does not meet the preset standard based on the beneficial component retention rate, the reason why the preparation of the purified liquid does not meet the preset standard is determined based on the absorbance ratio, wherein the reasons include excessive ozone oxidation and protein destruction; A preservative is added to the purified liquid that meets the preset standards to obtain a crop nutrient solution.

2. The method for preparing crop nutrient solution using kitchen fermentation biogas slurry according to claim 1, characterized in that: The treatment mode of the pre-treatment liquid is determined according to the pollution characterization value of the pre-treatment liquid, wherein: If the pollution characterization value is less than the first preset pollution characterization value, the pretreatment liquid is sterilized at a first preset sterilization temperature and a first preset sterilization time, and then subjected to ozone oxidation treatment after standing for a preset stratification time.

3. The method for preparing crop nutrient solution using kitchen fermentation biogas slurry according to claim 1, characterized in that: The treatment mode of the pre-treatment liquid is determined according to the pollution characterization value of the pre-treatment liquid, wherein: If the pollution characterization value is greater than or equal to the first preset pollution characterization value, high-temperature sterilization is performed according to the preset sterilization temperature and sterilization time, and flotation degreasing treatment and ozone oxidation treatment are performed in sequence before filtration.

4. The method for preparing crop nutrient solution using kitchen fermentation biogas slurry according to claim 2 or 3, characterized in that: The process of obtaining the pollution characterization value includes: respectively obtaining the turbidity and total bacterial count of the pretreatment liquid; The ratio of the turbidity of the pre-treated liquid to the preset turbidity is recorded as the turbidity ratio; The ratio of the total number of colonies in the pre-treated solution to the preset total number of colonies is recorded as the colony ratio; Multiplying the turbidity ratio by the first weight to obtain a turbidity evaluation value; Multiplying the colony ratio by the second weight to obtain a colony evaluation value; The turbidity evaluation value and the colony evaluation value are added to obtain the pollution characterization value.

5. The method for preparing crop nutrient solution using food fermentation biogas slurry according to claim 4, characterized in that: When the beneficial ingredient retention rate is less than a first preset retention rate, it is determined that the preparation of the purified liquid does not meet the preset standard, and the reason why the preparation of the purified liquid does not meet the preset standard is determined based on the absorbance ratio of the purified liquid; wherein the beneficial ingredient retention rate is jointly determined by the area of the protein characteristic peak and the area of the humic acid characteristic peak in the infrared spectrum of the purified liquid and the area of the protein characteristic peak and the area of the humic acid characteristic peak in the infrared spectrum of the pretreatment liquid.

6. The method for preparing crop nutrient solution using food fermentation biogas slurry according to claim 5, characterized in that: When the beneficial ingredient retention rate is greater than or equal to the first preset retention rate and less than the second preset retention rate, it is determined that the preparation of the purified liquid meets the preset standard, and a secondary determination is made as to whether the preparation of the purified liquid meets the preset standard based on the chromaticity deviation value of the purified liquid; The first preset retention rate is smaller than the second preset retention rate.

7. The method for preparing crop nutrient solution using food fermentation biogas slurry according to claim 6, characterized in that: The reason why the preparation of the purified liquid does not meet the preset standard is determined based on the absorbance ratio, wherein: If the absorbance ratio is less than a preset absorbance ratio, it is determined that the reason why the preparation of the purified liquid does not meet the preset standard is that the ozone oxidation of the pre-treated liquid is excessive; If the absorbance ratio is greater than or equal to the preset absorbance ratio, it is determined that the reason why the preparation of the purified liquid does not meet the preset standard is that the protein in the purified liquid is destroyed, and the preset sterilization temperature corresponding to the treatment mode adopted by the pretreatment liquid is reduced according to the difference between the absorbance ratio and the preset absorbance ratio; The absorbance ratio is the ratio between the ultraviolet absorbance of the protein characteristic peak and the ultraviolet absorbance of the humic acid characteristic peak of the purified liquid.

8. The method for preparing crop nutrient solution using food fermentation biogas slurry according to claim 7, characterized in that: The reduction range of the preset sterilization temperature corresponding to the treatment mode adopted by the pretreatment liquid is positively correlated with the difference between the absorbance ratio and the preset absorbance ratio.

9. The method for preparing crop nutrient solution using food fermentation biogas slurry according to claim 8, characterized in that: The preparation of the purified liquid is secondarily determined to be in compliance with the preset standard according to the chromaticity deviation value, wherein: If the chromaticity deviation value is less than the preset chromaticity deviation value, it is determined that the preparation of the purification liquid meets the preset standard; If the chromaticity deviation value is greater than or equal to the preset chromaticity deviation value, it is determined that the preparation of the purification liquid does not meet the preset standard, and the preset sterilization time corresponding to the treatment mode of the pretreatment liquid is reduced according to the ratio of the chromaticity deviation value to the preset chromaticity deviation value; The chromaticity deviation value is a ratio of a difference between the chromaticity of the purified liquid and a preset chromaticity to the preset chromaticity.

10. The method for preparing crop nutrient solution using food fermentation biogas slurry according to claim 9, characterized in that: The reduction range of the preset sterilization time corresponding to the treatment mode of the pretreatment liquid is positively correlated with the ratio of the chromaticity deviation value to the preset chromaticity deviation value.

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