Sludge-derived phytohormones and their directional preparation methods and applications

Abstract

The present invention relates to the technical field of resource treatment of organic solid waste, and discloses a sludge-derived plant stimulant, its directional preparation method and application. The method comprises the following steps: (1) subjecting the activated sludge in the aerobic tank of a municipal sewage treatment plant to ultrasonic conditioning to obtain an activated sludge raw material; (2) performing different conversion treatments on the activated sludge raw material to directionally prepare the sludge-derived plant stimulant. The method provided by the present invention can not only solve the problem of a large amount of sludge solid waste after sewage treatment and anaerobic digestion treatment, but also use it to directionally and efficiently prepare a high-value sludge-derived plant stimulant.

Description

Technical Field

[0001] The present invention relates to the technical field of resource treatment of organic solid waste, and particularly relates to sludge-derived phytohormones, a method for their directional preparation, and their applications. Background Art

[0002] With the increasing demand for wastewater treatment, the amount of sludge generated by global sewage treatment plants is increasing day by day. As a complex and highly water-containing organic solid waste, if sludge is not properly stabilized and reduced in quantity, it will cause secondary pollution of groundwater and soil after being eroded by rainwater and leaking. At the same time, sludge is also a rich resource library of carbon, nitrogen, and phosphorus, which contains various substances such as polysaccharides, amino acids, and humus that can be converted and utilized. Anaerobic digestion is one of the most widely used sludge resource treatment technologies, which can achieve sludge stabilization and produce excellent gaseous fuel, but it will also produce a large amount of digested sludge to be treated. Therefore, the development of sludge resource treatment technologies is of great significance for environmental protection and resource recycling.

[0003] With the increase in population, the demand for food is constantly rising, and with the frequent occurrence of extreme climates and pests and diseases, the work of ensuring food crops is becoming increasingly severe. Although the application of inorganic fertilizers and pesticides can increase food production, it will lead to a decline in the quality of crops and pose potential health threats and soil risks. Therefore, it is particularly important to find resources that can replace traditional fertilizers to improve agricultural productivity. Non-toxic and harmless phytohormones (including humic acid, protein hydrolysates, phytohormones, etc.) have thus received great attention. Among them, phytohormones are the most important signal molecules in plants, which can regulate the signal transduction pathways of plants, relieve internal and external stimuli, and resist biotic and abiotic stresses.

[0004] Research has found that the extract of sludge contains phytohormones, which have the potential to promote crop growth and resist pests, and can be used as liquid fertilizers. The development of sludge-derived phytohormone production technology provides a new idea for solving the contradiction between the rising demand for food and the deterioration of the global environment, and also brings opportunities for the resource utilization of organic solid waste. Currently, the research is still in its infancy, and the phytohormones contained in it are not clearly identified and cannot be regulated, so it cannot be effectively applied to crop production. There is an urgent need to provide a method for directionally preparing key phytohormone components through biological and chemical conversion technologies, so as to apply different types of sludge-derived phytohormone products according to the state of plants. Summary of the Invention

[0005] The object of the present invention is to overcome the above problems existing in the prior art.

[0006] To achieve the above object, in the first aspect of the present invention, a method for directionally preparing sludge-derived phytohormones is provided, and the method includes the following steps:

[0007] (1) Ultrasonically condition the activated sludge in the aerobic tank of the urban sewage treatment plant to obtain activated sludge raw materials;

[0008] (2) Carry out conversion treatment on the activated sludge raw materials to directionally prepare sludge-derived phytohormones, specifically including:

[0009] S1. When the target sludge-derived phytohormone is auxin-like hormone, first adjust the solid content rate of the activated sludge raw materials to 5-20 wt%, to obtain mixture I; then carry out first alkaline hydrolysis on the mixture I, and after separation, obtain auxin-like hormone;

[0010] S2. When the target sludge-derived phytohormone is jasmonic acid-like hormone, first adjust the solid content rate of the activated sludge raw materials to 3-5 wt%, to obtain mixture II; then carry out semi-anaerobic digestion biological treatment on the mixture II, and after solid-liquid separation, obtain sludge with a solid content rate of 5-20 wt%, and then carry out second alkaline hydrolysis, and after separation, obtain jasmonic acid-like hormone;

[0011] Among them, the operation of the semi-anaerobic digestion biological treatment includes: hydrolyzing and acidifying the mixture II in an anaerobic digestion device at a temperature of 35-45 °C and a pH of 4.6-5.8 in sequence to obtain the sludge.

[0012] The second aspect of the present invention provides a sludge-derived phytohormone prepared by the method described in the first aspect above.

[0013] The third aspect of the present invention provides the application of the sludge-derived phytohormone described in the second aspect above in promoting plant growth and / or improving plant resistance.

[0014] The method provided by the present invention can not only solve the problem of a large amount of sludge solid waste after sewage treatment and anaerobic digestion treatment, but also use it to directionally prepare high-value plant hormones.

[0015] Through different treatment methods, the sludge-derived phytohormone rich in auxin prepared by the present invention can be used as a liquid fertilizer to promote seedling germination and plant development after being diluted with water; the sludge-derived phytohormone rich in jasmonic acid prepared by the present invention can be used as a liquid fertilizer to resist biological and abiotic stresses during plant growth after being diluted with water.

[0016] In addition, the sludge-derived phytohormone prepared by the present invention also contains humic acid and exogenous nutrient components such as carbon, nitrogen, phosphorus, potassium, and calcium, which helps plants maintain homeostasis in basic physiological and metabolic processes and improve the comprehensive performance of growth and stress resistance. Description of the Drawings

[0017] Figure 1Flow chart for the directional preparation of sludge-derived phytohormones in Example 1;

[0018] Figure 2 Graph showing the changes in the total content of auxin phytohormones and jasmonate phytohormones in P1 before and after treatment in Example 1;

[0019] Figure 3 Graph showing the content performance of representative auxin substances in P1 in Example 1;

[0020] Figure 4 Content performance of representative jasmonate substances in P1 in Example 1;

[0021] Figure 5 Graph showing the changes in the total content of auxin phytohormones and jasmonate phytohormones in P3 before and after treatment in Example 2;

[0022] Figure 6 Graph showing the content performance of representative auxin substances in P3 in Example 2;

[0023] Figure 7 Graph showing the changes in the total content of auxin phytohormones and jasmonate phytohormones in P2 before and after treatment in Example 1;

[0024] Figure 8 Graph showing the content performance of representative auxin substances in P2 in Example 1;

[0025] Figure 9 Graph showing the content performance of representative jasmonate substances in P2 in Example 1. Detailed implementation manners

[0026] The endpoints and any values disclosed herein are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0027] As described above, the first aspect of the present invention provides a method for the directional preparation of sludge-derived phytohormones, and the method includes the following steps:

[0028] (1) Ultrasonically condition the aerobic activated sludge of the municipal sewage treatment plant to obtain activated sludge raw materials;

[0029] (2) Perform conversion treatment on the activated sludge raw materials to directionally prepare sludge-derived phytohormones, specifically including:

[0030] S1. When the target sludge-derived phytohormone is an auxin-like hormone, first adjust the solid content rate of the activated sludge raw material to 5-20 wt% to obtain mixture I; then perform first alkaline hydrolysis on mixture I, and after separation, obtain the auxin-like hormone;

[0031] S2. When the target sludge-derived phytohormone is a jasmonic acid-like hormone, first adjust the solid content rate of the activated sludge raw material to 3-5 wt% to obtain mixture II; then perform semi-anaerobic digestion biological treatment on mixture II, and after solid-liquid separation, obtain sludge with a solid content rate of 5-20 wt%, and then perform second alkaline hydrolysis, and after separation, obtain the jasmonic acid-like hormone;

[0032] Among them, the operations of the semi-anaerobic digestion biological treatment include: hydrolyzing and acidifying mixture II in an anaerobic digestion device at a temperature of 35-45 °C and a pH of 4.6-5.8 in sequence to obtain the sludge.

[0033] Preferably, the activated sludge in the aerobic tank of the urban sewage treatment plant is the activated sludge in the aerobic tank of the urban sewage treatment plant with a dissolved oxygen of 3.5-4.5 mg / L and a COD load of 0.60-0.8 kg COD / m 3 ·d.

[0034] Preferably, the method of the present invention further includes: in step (1), before performing the ultrasonic conditioning, first settle the activated sludge in the aerobic tank of the urban sewage treatment plant for 24 h and then filter it with a 20-mesh sieve to remove inorganic gravel.

[0035] Preferably, in step (1), the conditions of the ultrasonic conditioning at least satisfy: the energy density is 0.1-0.2 W / mL, and the time is 3-6 min.

[0036] Preferably, the method of adjusting the solid content rate of the activated sludge raw material is at least one of adding water, sedimentation and concentration, vacuum filtration, and plate and frame pressure filtration.

[0037] According to a preferred specific embodiment, the method of the present invention further includes: the first alkaline hydrolysis and / or the second alkaline hydrolysis are carried out in a hydrolysis reactor, and the operation steps include: first adjust the pH of mixture I or mixture II to 10-12, then heat to 45-55 °C for low-temperature holding for 8-13 min, and then heat to 120-200 °C for high-temperature holding for 1-3 h, and after cooling, perform the separation.

[0038] Preferably, the cooling is to reduce the temperature to 20-30 °C.

[0039] Preferably, the time of the high-temperature holding is 2 h.

[0040] Preferably, the pH of the mixture I or the mixture II is adjusted by adding CaO, and the addition amount is 10-15 wt% of the dry weight of the sludge solids in the mixture I or the mixture II.

[0041] Preferably, the first alkaline hydrolysis and / or the second alkaline hydrolysis is carried out under stirring conditions with a rotation speed of 200-300 rpm, and the rotation direction of the stirrer is changed every 10-30 minutes to achieve the purpose of thorough mixing.

[0042] Preferably, in step S2, the total time of the hydrolysis and the acidification is 3-8 days.

[0043] According to a preferred embodiment, in step S2, the operation of the semi-anaerobic digestion biological treatment includes: introducing nitrogen gas into the anaerobic digestion device with a stirring function for 2 minutes in advance to create an anaerobic state, then placing the mixture II in the device, hydrolyzing and acidifying at 35-45 °C, and then performing the subsequent solid-liquid separation.

[0044] According to a preferred specific embodiment, the operation of the separation includes: sequentially performing high-speed centrifugation and filtration on the product of the first alkaline hydrolysis or the second alkaline hydrolysis, and then taking the supernatant;

[0045] Among them, the rotation speed of the high-speed centrifugation is 7000-9000 rpm, the time is 9-15 minutes, and the average pore diameter of the filter membrane used for the filtration is 0.45 μm.

[0046] Preferably, the auxin-like hormone contains indole-3-acetic acid.

[0047] Preferably, the auxin-like hormone further contains at least one of L-tryptophan, indole, indole-3-lactic acid, and indole-3-propionic acid.

[0048] Preferably, in the auxin-like hormone, the total content of auxin-like plant hormones is 10 4 -10 6 μg / L.

[0049] It should be noted that the total content of auxin-like plant hormones includes the total content of auxin-like plant hormones including indole-3-acetic acid, L-tryptophan, indole, indole-3-lactic acid, and indole-3-propionic acid.

[0050] Preferably, the jasmonic acid-like hormone contains jasmonic acid, and in the jasmonic acid-like hormone, the total content of jasmonic acid-like plant hormones is 10 3 -10 5 μg / L.

[0051] More preferably, the jasmonate hormones further contain pentenyl cyclopentane butyric acid and / or 12-oxo-phytodienoic acid.

[0052] As described above, the second aspect of the present invention provides a sludge-derived plant stimulant prepared by the method described in the first aspect above.

[0053] As described above, the third aspect of the present invention provides the use of the sludge-derived plant stimulant described in the second aspect above in promoting plant growth and / or improving plant resistance.

[0054] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, the raw materials are commercially available products.

[0055] Activated sludge from the aerobic tank of a municipal sewage treatment plant: Activated sludge from the aerobic tank with a dissolved oxygen of 3.5 - 4.5 mg / L and a COD load of 0.8 kg COD / m 3 ·d taken from the Shanghai Hongqiao Municipal Sewage Treatment Plant.

[0056] In the following examples, unless otherwise specified, the total volume of the hydrothermal reactor is 3 L and the working volume is 2 L;

[0057] The total volume of the anaerobic digestion device is 5 L and the working volume is 3 L;

[0058] Example 1

[0059] This example is used to combine Figure 1 To provide a preferred method for the directional preparation of sludge-derived plant stimulants, the method includes the following steps:

[0060] (1) After sedimenting the activated sludge from the aerobic tank of the municipal sewage treatment plant for 24 h, it is filtered through a 20-mesh sieve to remove inorganic gravel, and then ultrasonically conditioned for 3 min at an energy density of 0.1 W / mL to obtain the activated sludge raw material;

[0061] (2) Carry out conversion treatment on the activated sludge raw material to directionally prepare a sludge-derived plant stimulant, specifically including:

[0062] S1. Using auxin hormones as the target sludge-derived plant stimulant, first adjust the solid content of the activated sludge raw material to 5 wt% to obtain mixture I;

[0063] Then, 7.5 g of CaO was added to the mixture I, the pH was adjusted to 12, and then it was transferred to a hydrothermal reactor. Stirring was started (the rotation speed was 200 rpm and the rotation direction of the stirrer was changed every 20 min). The temperature was heated to 50 °C and kept at a low temperature for 10 min, and then heated to 120 °C and kept at a high temperature for 2 h for the first alkaline hydrothermal hydrolysis. After cooling to 25 °C, centrifugation was carried out at a rotation speed of 8000 rpm for 10 min, and then filtration was carried out using a filter membrane with an average pore diameter of 0.45 μm. The supernatant was taken to obtain auxin-like hormones, named P1;

[0064] S2. Using jasmonic acid-like hormones as the target sludge-source plant stimulant, first adjust the solid content of the activated sludge raw material to 3.12 wt% to obtain mixture II;

[0065] Then, the mixture II was transferred to an anaerobic digestion device with a stirring function, and nitrogen was introduced for 2 min to create an anaerobic state. Then, the mixture II was placed in this device, and hydrolysis and acidification were carried out at 37 °C for 8 days for semi-anaerobic digestion biological treatment. After solid-liquid separation to adjust the solid content, sludge with a solid content of 7.8 wt% was obtained, and CaO was added to adjust the pH to 12;

[0066] Subsequently, it was transferred to a hydrothermal reactor. Stirring was started (the rotation speed was 200 rpm and the rotation direction of the stirrer was changed every 20 min). The temperature was heated to 50 °C and kept at a low temperature for 10 min, and then heated to 120 °C and kept at a high temperature for 2 h for the second alkaline hydrothermal hydrolysis. After cooling to 25 °C, centrifugation was carried out at a rotation speed of 8000 rpm for 10 min, and then filtration was carried out using a filter membrane with an average pore diameter of 0.45 μm. The supernatant was taken to obtain jasmonic acid-like hormones, named P2.

[0067] Example 2

[0068] (1) The aerobic activated sludge of the municipal wastewater treatment plant was settled for 24 h and then passed through a 20-mesh sieve to filter out inorganic gravel. Then, ultrasonic conditioning was carried out at an energy density of 0.15 W / mL for 6 min to obtain the activated sludge raw material;

[0069] (2) The activated sludge raw material was subjected to a conversion treatment to directionally prepare sludge-source plant stimulants, specifically including:

[0070] S1. Using auxin-like hormones as the target sludge-source plant stimulant, the solid content of the activated sludge raw material was adjusted to 14 wt% by means of plate and frame filtration to obtain mixture I;

[0071] Then, CaO is added to the mixture I, and the pH is adjusted to 12. Then, it is transferred to a hydrothermal reactor, and stirring is started (the rotation speed is 200 rpm and the rotation direction of the stirrer is changed every 20 minutes). The temperature is heated to 50 °C and maintained at a low temperature for 10 minutes, and then heated to 160 °C and maintained at a high temperature for 2 h for the first alkaline hydrothermal treatment. After cooling to 25 °C, it is centrifuged at a rotation speed of 8000 rpm for 10 minutes, and then filtered using a filter membrane with an average pore diameter of 0.45 μm. The supernatant is taken to obtain auxin-like hormones, named P3.

[0072] Example 3

[0073] This example is carried out in a similar manner to Example 1, except that in step (2), the operation of maintaining at a low temperature is not performed, specifically including:

[0074] (2) The activated sludge raw material is subjected to a conversion treatment to directionally prepare sludge-derived plant stimulants, specifically including:

[0075] S1. Using auxin-like hormones as the target sludge-derived plant stimulants, first adjust the solid content rate of the activated sludge raw material to 5 wt% to obtain mixture I;

[0076] Then, 7.5 g of CaO is added to the mixture I, the pH is adjusted to 12, and then it is transferred to a hydrothermal reactor. Stirring is started (the rotation speed is 200 rpm and the rotation direction of the stirrer is changed every 20 minutes). The temperature is directly heated to 120 °C and maintained at a high temperature for 2 h for the first alkaline hydrothermal treatment. After cooling to 25 °C, it is centrifuged at a rotation speed of 8000 rpm for 10 minutes, and then filtered using a filter membrane with an average pore diameter of 0.45 μm. The supernatant is taken to obtain auxin-like hormones, named P4;

[0077] S2. Using jasmonic acid-like hormones as the target sludge-derived plant stimulants, first adjust the solid content rate of the activated sludge raw material to 3.12 wt% to obtain mixture II;

[0078] Then, the mixture II is transferred to an anaerobic digestion device with a stirring function, and nitrogen is introduced for 2 minutes to create an anaerobic state. Then, the mixture II is placed in the device and hydrolyzed and acidified at 37 °C for 8 days for semi-anaerobic digestion biological treatment. After solid-liquid separation to adjust the solid content rate, sludge with a solid content rate of 7.8 wt% is obtained, and CaO is added to adjust the pH to 12;

[0079] Subsequently, it was transferred to a hydrothermal reactor, the stirring was started (the rotation speed was 200 rpm and the rotation direction of the stirrer was changed every 20 min), the temperature was directly heated to 120 °C and held at a high temperature for 2 h for the second alkaline hydrothermal hydrolysis. After cooling to 25 °C, it was centrifuged at 8000 rpm for 10 min, and then filtered using a filter membrane with an average pore diameter of 0.45 μm. The supernatant was taken to obtain jasmonate hormones, named P5.

[0080] Comparative Example 1

[0081] This example was carried out in a similar manner to Example 1, except that in step (1), ultrasonic conditioning was not performed, specifically including:

[0082] (1) The aerobic activated sludge from the municipal wastewater treatment plant was settled for 24 h and then passed through a 20-mesh sieve to filter out inorganic gravel, obtaining the activated sludge raw material;

[0083] Finally, auxin hormones (named P6) and jasmonate hormones (named P7) were obtained.

[0084] Test Example 1

[0085] Using the LC-MS / MS high-sensitivity platform and referring to the self-built database, the component quantitative analysis of the auxin hormones prepared in the above example part was carried out, and the results are as follows:

[0086] For P1:

[0087] As Figure 2 shown, compared with before treatment (i.e., mixture I in Example 1), in P1, the total content of auxin plant hormones increased significantly, from 15832.70 μg / L to 79341.10 μg / L, while the total content of jasmonate plant hormones did not change significantly, indicating that auxin hormones were successfully prepared by this method.

[0088] Among them, in P1, among the 17 detected auxins, the contents from high to low are L-tryptophan, indole-3-acetic acid, indole, indole-3-propionic acid, indole-3-lactic acid, indole-3-carboxaldehyde, oxindoleacetic acid, indole-3-carboxylic acid, tryptamine, indole-3-acrylic acid, indoleacetic acid-leucine, N-(3-indolylacetyl)-L-phenylalanine, indoleacetic acid-valine, indoleacetic acid-tryptophan, 3-indoleacetamide, methyl indole-3-acetate, indoleacetic acid-glycine. Among them, as Figure 3As shown, in P1, the content of L-tryptophan is 66109.20 μg / L, the content of indole-3-acetic acid is 6594.68 μg / L, the content of indole is 4936.38 μg / L, the content of indole-3-propionic acid is 1114.89 μg / L, and the content of indole-3-lactic acid is 140.70 μg / L.

[0089] Among them, in P1, the total content of jasmonate phytohormones detected is less than 150 μg / L, including (E)-12-oxo-phytodienoic acid and 12-oxo-phytodienoic acid. Among them, as Figure 4 shown, in P1, the content of (E)-12-oxo-phytodienoic acid is 127.01 μg / L, and the content of 12-oxo-phytodienoic acid is 11.44 μg / L.

[0090] In addition, the obtained supernatant also contains 1.05 g / L of total dissolved nitrogen, 1.30 g / L of humic acid, and 2.43 g / L of protein (in the actual plant application process, after preparing P1 and water in a volume ratio of 1:30, it can be used as a foliar fertilizer to promote growth).

[0091] For P3:

[0092] A total of 22 auxins were detected. As Figure 5 shown, compared with before treatment (mixture I in Example 2), in P3, the total content of auxin phytohormones increased from 249.31 μg / L to 15619.14 μg / L, while the total content of jasmonate phytohormones changed little before and after treatment, indicating that this method successfully prepared auxin hormones.

[0093] Among them, in P3, the detected auxins are ranked from high to low as indole, L-tryptophan, indole-3-lactic acid, indole-3-acetic acid, oxindoleacetic acid, indole-3-carboxaldehyde, tryptamine, indole-3-propionic acid, indole-3-acrylic acid, indole-3-carboxylic acid, indoleacetic acid-aspartic acid, N-(3-indolylacetyl)-L-alanine, indole-3-butyric acid, indoleacetic acid-leucine, indoleacetic acid-dimethyl glutamate, methyl indole-3-acetate, indoleacetic acid-glutamic acid, 3-indoleacetamide, N-(3-indolylacetyl)-L-phenylalanine, indole-3-acetonitrile, indoleacetic acid-tryptophan, and methyl indoleacetic acid-phenylalanine. Among them, in P3, as Figure 6 shown, the content of indole is 10528.71 μg / L, the content of L-tryptophan is 10528.74 μg / L, the content of indole-3-lactic acid is 4449.44 μg / L, the content of indole-3-acetic acid is 1063.27 μg / L, and the content of oxindoleacetic acid is 553.95 μg / L.

[0094] In addition, in P3, there is also 5.92 g / L of total dissolved nitrogen, 7.98 g / L of humic acid, 13.68 g / L of protein, 0.33 g / L of total potassium, and 0.38 g / L of total phosphorus (in the actual process of plant application, after P3 and water are prepared at a volume ratio of 1:20, it can be used as a foliar fertilizer to promote growth).

[0095] For P4:

[0096] Compared with before treatment (i.e., mixture I in Example 3), in P4, the total content of auxin plant hormones has increased, from 13354.40 μg / L to 27864.80 μg / L, while the total content of jasmonic acid plant hormones has decreased, indicating that this method successfully prepares auxin hormones.

[0097] Among them, in P4, among the 15 detected auxins, the contents from high to low are L-tryptophan, indole, indole-3-acetic acid, indole-3-carboxaldehyde, indole-3-lactic acid, oxindoleacetic acid, tryptamine, indole-3-carboxylic acid, 3-indolepropionic acid, N-(3-indoleacetyl)-L-alanine, 3-indoleacetamide, indoleacetic acid-aspartic acid, indoleacetic acid-leucine, indole-3-acetonitrile, N-(3-indoleacetyl)-L-phenylalanine. Among them, the contents of the first 4 substances are 24531.80 μg / L (L-tryptophan), 2740.10 μg / L (indole), 253.50 μg / L (indole-3-acetic acid), and 113.5 μg / L (indole-3-carboxaldehyde), and the contents of the remaining 11 substances are all lower than 100 μg / L.

[0098] Among them, in P4, the total content of the 4 detected jasmonic acids is 77.60 μg / L, and the contents of each substance are 29.50 μg / L of 12-hydroxyjasmonic acid, 27.10 μg / L of 12-oxo-phytodienoic acid, 18.70 μg / L of dihydrojasmonic acid, and 2.4 μg / L of jasmonic acid.

[0099] In addition, the obtained supernatant also contains 0.73 g / L of total dissolved nitrogen, 3.98 g / L of humic acid, and 8.32 g / L of protein (in the actual process of plant application, after P4 and water are prepared at a volume ratio of 1:15, it can be used as a foliar fertilizer to promote growth).

[0100] For P6:

[0101] Compared with before treatment (i.e., mixture I in Comparative Example 1), in P6, the growth rate of the total content of auxin plant hormones is relatively small, only increasing from 12974.60 μg / L to 19846.40 μg / L, indicating that auxin hormones cannot be effectively prepared and the practical application value is relatively small.

[0102] Among them, in P6, among the 15 auxins detected, the contents from high to low are L-tryptophan, indole, tryptamine, indole-3-acetic acid, indole-3-carboxaldehyde, indole-3-carboxylic acid, indole-3-lactic acid, oxindoleacetic acid, 3-indolepropionic acid, N-(3-indoleacetyl)-L-alanine, 3-indoleacetamide, indoleacetic acid-aspartic acid, indoleacetic acid-leucine, indole-3-acetonitrile, N-(3-indoleacetyl)-L-phenylalanine. Among them, the contents of the first 4 substances are 17369.80 μg / L (L-tryptophan), 2049.50 μg / L (indole), 254.00 μg / L (tryptamine), and 173.10 μg / L (indole-3-acetic acid), respectively.

[0103] Test Example 2

[0104] Using the LC-MS / MS high-sensitivity platform and referring to the self-built database, the component quantitative analysis of the jasmonic acid hormones prepared in the above example part was carried out, and the results are as follows:

[0105] For P2:

[0106] A total of 14 auxins and 3 jasmonic acids were detected in P2. As Figure 7 shown, compared with before treatment (mixture II in Example 1), the total content of jasmonic acid plant hormones increased significantly from 138.38 μg / L to 2657.77 μg / L, while the total content of auxin plant hormones decreased, and there was a significant increase in the type and content of jasmonic acid compared with P1, indicating that the method successfully prepared jasmonic acid hormones.

[0107] Among them, as Figure 8 shown, in P2, the content of L-tryptophan in the detected auxins is 1665.33 μg / L, the content of indole-3-acetic acid is 353.22 μg / L, the content of indole-3-propionic acid is 304.96 μg / L, the content of indole is 139.47 μg / L, and the content of indole-3-lactic acid is 14.24 μg / L.

[0108] Among them, the total content of jasmonic acid plant hormones detected in P2 exceeds 2600 μg / L, including oxopentenyloxycyclopentanebutanoic acid, 12-oxo-phytodienoic acid, jasmonic acid. Among them, as Figure 9 shown, the content of oxopentenyloxycyclopentanebutanoic acid is 2037.28 μg / L, the content of 12-oxo-phytodienoic acid is 491.48 μg / L, and the content of jasmonic acid is 129.01 μg / L.

[0109] In addition, P2 also contains 2.89 g / L of total dissolved nitrogen, 1.47 g / L of humic acid, and 1.23 g / L of protein (in the actual application process for plants, when P2 and water are prepared in a volume ratio of 1:20, it can be used as a foliar fertilizer for pest control).

[0110] For P5:

[0111] A total of 13 auxins and 3 jasmonic acids were detected in P5. Compared with before treatment (mixture II in Example 3), the total content of jasmonic acid plant hormones increased significantly from 203.38 μg / L to 1465.70 μg / L, while the total content of auxin plant hormones decreased. There was a significant increase in the total content of jasmonic acid plant hormones compared with P4, indicating that the method successfully prepared jasmonic acid hormones.

[0112] Among them, the content of L-tryptophan in the auxins detected in P5 was 2043.30 μg / L, the content of indole was 539.47 μg / L, the content of indole-3-acetic acid was 383.60 μg / L, the content of indole-3-propionic acid was 222.50 μg / L, and the content of indole-3-carboxaldehyde was 94.24 μg / L.

[0113] Among them, the jasmonic acid plant hormones detected in P5 included pentenylcyclopentane butyric acid, 12-oxo-phytodienoic acid, and jasmonic acid. Among them, the content of pentenylcyclopentane butyric acid was 1207.50 μg / L, the content of 12-oxo-phytodienoic acid was 209.40 μg / L, and the content of jasmonic acid was 48.80 μg / L.

[0114] In addition, P5 also contains 1.89 g / L of total dissolved nitrogen, 5.98 g / L of humic acid, and 4.91 g / L of protein (in the actual application process for plants, when P5 and water are prepared in a volume ratio of 1:10, it can be used as a foliar fertilizer for pest control).

[0115] For P7:

[0116] Compared with before treatment (mixture II in Comparative Example 1), the increase in the total content of jasmonic acid plant hormones was relatively small, from 157.40 μg / L to 318.56 μg / L, indicating that the practical application value of the jasmonic acid hormones prepared by this method is relatively small.

[0117] Among them, there were 3 kinds of jasmonic acids detected in P7, including pentenylcyclopentane butyric acid, 12-oxo-phytodienoic acid, and jasmonic acid. Among them, the content of pentenylcyclopentane butyric acid was 263.64 μg / L, the content of 12-oxo-phytodienoic acid was 33.67 μg / L, and the content of jasmonic acid was 21.25 μg / L.

[0118] As can be seen from the above, the method of the present invention can not only solve the problem of a large amount of sludge solid waste after sewage treatment and anaerobic digestion treatment, but also use it to efficiently prepare high-value sludge-derived plant stimulants in a targeted manner, and apply different types of sludge-derived plant stimulants as appropriate according to the plant state to respectively achieve the effects of promoting plant growth and enhancing plant resistance against external stresses.

[0119] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for directional preparation of sludge-derived plant stimulants, characterized in that: The method comprises the following steps: (1) Ultrasonic conditioning is performed on the activated sludge in the aerobic tank of a municipal sewage plant to obtain activated sludge raw material; (2) converting the activated sludge raw material to prepare sludge-derived plant stimulants in a targeted manner, specifically comprising: S1. When the target sludge source plant stimulant is an auxin hormone, firstly adjusting the solid content of the activated sludge raw material to 5-20wt% to obtain a mixture I; then performing a first alkaline thermal hydrolysis on the mixture I to obtain the auxin hormone after separation; S2. When the target sludge source plant stimulant is a jasmonic acid hormone, the solid content of the activated sludge raw material is first adjusted to 3-5wt% to obtain a mixture II; then the mixture II is subjected to semi-anaerobic digestion biological treatment to obtain a sludge with a solid content of 5-20wt% after solid-liquid separation, and then subjected to a second alkaline thermal hydrolysis to obtain a jasmonic acid hormone after separation; The operation of the semi-anaerobic digestion biological treatment includes: hydrolyzing and acidifying the mixture II in an anaerobic digestion device at a temperature of 35-45°C and a pH of 4.6-5.8 to obtain the sludge; the total time of the hydrolysis and the acidification is 3-8 days; The first alkaline thermal hydrolysis and / or the second alkaline thermal hydrolysis are carried out in a thermal hydrolysis reactor, and the operation steps include: first adjusting the pH of the mixture I or the mixture II to 10-12, then heating to 45-55°C for low temperature maintenance for 8-13 minutes, then heating to 120-200°C for high temperature maintenance for 1-3 hours, and performing the separation after cooling.

2. The method according to claim 1, characterized in that The activated sludge in the aerobic tank of the municipal sewage plant has a dissolved oxygen content of 3.5-4.5 mg / L and a COD load of 0.60-0.8 kg COD / m 3 ·d. Activated sludge in aerobic tanks of urban sewage plants.

3. The method according to claim 1 or 2, characterized in that: In step (1), the conditions for the ultrasonic conditioning at least meet the following requirements: energy density is 0.1-0.2 W / mL, and time is 3-6 min.

4. The method according to claim 1 or 2, characterized in that: The separation operation includes: sequentially subjecting the product of the first alkaline thermal hydrolysis or the second alkaline thermal hydrolysis to high-speed centrifugation and filtration, and then taking the supernatant; The rotation speed of the high-speed centrifugation is 7000-9000 rpm, the time is 9-15 min, and the average pore diameter of the filter membrane used in the filtration is 0.45 μm.

5. The method according to claim 1 or 2, characterized in that: In the auxin hormone, the total content of auxin plant hormone is 10 4 -10 6 μg / L.

6. The method according to claim 1 or 2, characterized in that: The jasmonic acid hormone contains jasmonic acid, and in the jasmonic acid hormone, the total content of jasmonic acid plant hormone is 10 3 -10 5 μg / L.

7. The sludge-derived plant stimulant prepared by the method according to any one of claims 1 to 6.

8. Use of the sludge-derived plant stimulant according to claim 7 in promoting plant growth and / or improving plant resistance.

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