Method for producing humic acid-containing liquid fertilizer from organic wastewater and application of humic acid-containing liquid fertilizer

Abstract

The invention belongs to the technical field of wastewater treatment and resource utilization, and particularly relates to a method for producing a humic acid-containing liquid fertilizer from organic wastewater and application of the humic acid-containing liquid fertilizer. According to the method, the organic wastewater and the phenolic compound (catechol and / or resorcinol) are mixed and subjected to a hydrothermal reaction under the closed condition, and the humic acid-containing liquid fertilizer is obtained. According to the method disclosed by the invention, organic matters in the organic wastewater can be converted into humic acid, and the added value of the organic wastewater is improved. The humic acid-containing liquid fertilizer has the characteristic of high humic acid content, can be used as a humic acid water-soluble fertilizer, and has certain fertilizer efficiency and economic feasibility. The method has the characteristics of short time and simple process. Furthermore, the humification process is synergistically enhanced by adding a catalyst and filling oxygen, so that the humic acid content in the humic acid-containing liquid fertilizer is further increased to 30 g / L, and the possibility of preparing the humic acid water-soluble fertilizer is improved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment and resource utilization, and in particular to a method for producing liquid fertilizer containing humic acid by using organic wastewater and application thereof. Background Art

[0002] Organic wastewater mainly refers to COD and BOD 5 Wastewater that reaches or exceeds several thousand or even tens of thousands of milligrams per liter mainly comes from the fields of food processing, coking, pharmaceuticals, papermaking, printing and dyeing, petrochemicals, and livestock and poultry farming. Organic wastewater usually has the following characteristics: high concentration of organic matter, complex composition, unstable effluent quality, more biodegradable substances, high content of toxic and harmful substances, high salt content, high turbidity and chromaticity, and some wastewater emits a foul odor. Among them, some organic wastewater, such as livestock and poultry breeding wastewater, contains high nutrients such as N, P, and K, and has the potential for resource utilization such as liquid fertilizer. Organic wastewater contains a large amount of toxic organic matter. If it is discharged directly without treatment, it will continue to accumulate and store in natural environments such as water bodies and soil, and then enter organisms through the food chain and gradually enrich, and finally enter the human body, endangering human health.

[0003] Most of the treatment technologies for organic wastewater first use physical and chemical treatment methods for pretreatment, such as coagulation, adsorption, and advanced oxidation, to improve the biodegradability of wastewater, and then use traditional biological treatment technologies, such as the AA / O method, which uses reclaimed water as the main resource utilization method. However, these treatment methods only decompose most of the organic matter instead of storing it or converting it for utilization, and the added value is low. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a method for producing liquid fertilizer containing humic acid from organic wastewater and its application. The method of the present invention can convert organic pollutants in organic wastewater into humic acid with application value, thereby increasing the added value of organic wastewater.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for producing liquid fertilizer containing humic acid from organic wastewater, comprising the following steps:

[0007] The organic wastewater and phenolic compounds are mixed and subjected to a hydrothermal reaction under closed conditions to obtain a liquid fertilizer containing humic acid;

[0008] The phenolic compound is catechol and / or resorcinol.

[0009] Preferably, the BOD in the organic wastewater is greater than or equal to 10500 mg / L; the organic wastewater includes one or more of kitchen waste wastewater, livestock and poultry breeding wastewater, slaughter wastewater, and food wastewater.

[0010] Preferably, the dosage ratio of the phenolic compound to the organic wastewater is 0.01 - 1.5 g / L.

[0011] Preferably, the pH value of the mixed system obtained by mixing is 5 - 11.

[0012] Preferably, the organic wastewater is also mixed with a catalyst; the catalyst includes one or more of manganese dioxide, zinc oxide, and iron oxide.

[0013] Preferably, the dosage ratio of the catalyst to the organic wastewater is 0.01 - 1.5 g / L.

[0014] Preferably, after the mixing and before the hydrothermal reaction, oxygen is also filled; the filling pressure of the oxygen is 0.11 - 1.5 MPa.

[0015] Preferably, the temperature of the hydrothermal reaction is 160 - 220 °C, and the time is 0.5 - 2 h.

[0016] The present invention also provides a humic acid liquid fertilizer obtained by the method described in the above technical solution.

[0017] The present invention also provides the application of the humic acid liquid fertilizer described in the above technical solution in the field of fertilizers.

[0018] The present invention provides a method for producing a humic acid liquid fertilizer from organic wastewater.

[0019] (1) Traditional physical and chemical treatment methods will cause the organic matter in the organic wastewater to be decomposed, consume energy, and require a large amount of capital investment; the method of the present invention can realize the conversion of the organic matter in the organic wastewater into humic acid, improving the added value of the organic wastewater.

[0020] (2) The humic acid liquid fertilizer obtained by the method of the present invention has the characteristic of high humic acid content, can be used as a humic acid water-soluble fertilizer, and has certain fertilizer efficiency and economic feasibility.

[0021] (3) In traditional physical and chemical treatment methods, the processes of flocculation, adsorption, and biological treatment all require a long time, and the method of the present invention has the characteristics of short time and simple process.

[0022] (4) The method of the present invention is a chemical treatment with wide applicability.

[0023] (5) The method of the present invention can convert the organic matter in organic wastewater into humic acid, providing a new idea for the preparation of humic acid and is expected to reduce the dependence on the traditional humic acid resources extracted from coal mines.

[0024] (6) Further, the present invention adds a catalyst and fills oxygen, synergistically strengthening the humification process, so that the humic acid content in the liquid fertilizer containing humic acid obtained after the hydrothermal reaction is further increased to 30 g / L, improving the possibility of making the liquid fertilizer containing humic acid into a water-soluble humic acid fertilizer.

[0025] (7) The water-soluble humic acid fertilizer prepared from the liquid fertilizer containing humic acid obtained after the hydrothermal reaction has a certain improvement effect on the yield and quality of crops such as pakchoi compared with ordinary chemical fertilizers. Description of the Drawings

[0026] Figure 1 It is a range analysis result diagram of the humic acid content in the liquid fertilizers containing humic acid obtained in Examples 1 to 12 and Comparative Examples 1 to 4;

[0027] Figure 2 It is a three-dimensional fluorescence spectrum of DOM of the liquid fertilizers containing humic acid obtained in Examples 1 to 12 and Comparative Examples 1 to 4;

[0028] Figure 3 It is a range analysis result diagram of the fluorescence region integral of the liquid fertilizers containing humic acid obtained in Examples 1 to 12 and Comparative Examples 1 to 4;

[0029] Figure 4 It is a range analysis result diagram of the humic acid content in the liquid fertilizers containing humic acid obtained in Examples 13 to 28;

[0030] Figure 5 It is a three-dimensional fluorescence spectrum of DOM of the liquid fertilizers containing humic acid obtained in Examples 13 to 28;

[0031] Figure 6 It is a range analysis result diagram of the fluorescence region integral of the liquid fertilizers containing humic acid obtained in Examples 13 to 28;

[0032] Figure 7 It is the fresh weight of pakchoi under different fertilization treatments;

[0033] Figure 8 It is the dry weight of pakchoi under different fertilization treatments;

[0034] Figure 9 It is the SPAD value of pakchoi under different fertilization treatments;

[0035] Figure 10 It is the soluble sugar of pakchoi under different fertilization treatments;

[0036] Figure 11The vitamin C of pakchoi under different fertilization treatments. Detailed implementation manners

[0037] Belongs to the explanation: The BOD refers to the biochemical oxygen demand, which is used to represent the content of easily degradable organic matter in organic wastewater.

[0038] The present invention provides a method for producing a humic acid-containing liquid fertilizer from organic wastewater, comprising the following steps:

[0039] Perform a hydrothermal reaction on the organic wastewater and phenolic compounds under closed conditions to obtain a humic acid-containing liquid fertilizer;

[0040] The phenolic compound is catechol and / or resorcinol.

[0041] Unless otherwise specified, the raw materials used in the present invention are preferably commercially available products.

[0042] In the present invention, the organic wastewater preferably enriches easily degradable organic matter; the BOD in the organic wastewater is preferably greater than or equal to 10500 mg / L. In the specific implementation manners of the present invention, the organic wastewater preferably includes one or more of food waste water, livestock and poultry breeding wastewater, slaughter wastewater, and food processing wastewater. In the present invention, the preparation method of the food waste water preferably includes the following steps: The food waste is subjected to three-phase separation, and the obtained liquid phase is the food waste water.

[0043] In the present invention, the phenolic compound is catechol and / or resorcinol, preferably catechol. In the present invention, the dosage ratio of the phenolic compound to the organic wastewater is preferably 0.01 - 1.5 g / L, more preferably 0.5 - 1.5 g / L, specifically preferably 0.01 g / L, 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L or 1.5 g / L. In the present invention, the phenolic compound, as a precursor for the production of humic acid, can form humic acid through oxidation polymerization and other reactions during the subsequent hydrothermal reaction process.

[0044] In the present invention, the organic wastewater is preferably further mixed with a catalyst; the catalyst preferably comprises one or more of manganese dioxide, zinc oxide and iron oxide, and more preferably manganese dioxide. In the present invention, the dosage ratio of the catalyst to the organic wastewater is preferably 0.01 - 1.5 g / L, more preferably 0.1 - 1.5 g / L, and specifically preferably 0.01 g / L, 0.05 g / L, 0.1 g / L, 0.2 g / L, 0.3 g / L, 0.4 g / L, 0.5 g / L, 0.6 g / L, 0.7 g / L, 0.8 g / L, 0.9 g / L, 1 g / L, 1.1 g / L, 1.2 g / L, 1.3 g / L, 1.4 g / L or 1.5 g / L. In the present invention, the catalyst can catalyze phenolic compounds and organic matter in the organic wastewater to form humic acid through oxidative polymerization, further improving the production efficiency of humic acid.

[0045] In the present invention, the pH value of the mixed system obtained by mixing is preferably 5 - 11, and specifically preferably 5, 6, 7, 8, 9, 10 or 11. The present invention does not specifically limit the reagent for adjusting the pH value of the mixed system, as long as the requirements can be met.

[0046] After the mixing and before the hydrothermal reaction, the present invention preferably further includes charging oxygen; the charging pressure of the oxygen is preferably 0.11 - 1.5 MPa, more preferably 0.5 - 1.5 MPa, and specifically preferably 0.11 MPa, 0.12 MPa, 0.13 MPa, 0.14 MPa, 0.15 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa or 1.5 MPa. In the present invention, the charging of oxygen preferably includes the following steps: introducing oxygen to discharge the air in the reaction kettle, closing the gas valve on one side of the reaction kettle and continuing to charge oxygen until the pressure of the reaction kettle reaches the target pressure, and then stopping the introduction of oxygen. In the present invention, the charging of oxygen can further promote the oxidative polymerization of phenolic compounds to form humic acid, improving the production efficiency of humic acid.

[0047] In the present invention, the temperature of the hydrothermal reaction is preferably 160 - 220 °C, and specifically preferably 160 °C, 170 °C, 180 °C, 190 °C, 200 °C, 210 °C or 220 °C.

[0048] In the present invention, the time of the hydrothermal reaction is preferably 0.5 - 2 h, and specifically preferably 0.5 h, 1 h, 1.5 h or 2 h.

[0049] In the present invention, the hydrothermal reaction is preferably carried out in a reaction kettle, and the volume of the organic wastewater preferably accounts for 60-80% of the effective volume of the reaction kettle, specifically preferably 60%, 65%, 70%, 75% or 80%.

[0050] After the hydrothermal reaction is completed, the present invention preferably further includes naturally cooling to room temperature to obtain a humic acid liquid fertilizer.

[0051] The present invention also provides a humic acid liquid fertilizer obtained by the method of the above technical solution. In the present invention, the content of humic acid in the humic acid liquid fertilizer is preferably 30.4-30.6 g / L.

[0052] The present invention also provides the application of the humic acid liquid fertilizer described in the above technical solution in the field of fertilizers.

[0053] The present invention does not specifically limit the application method of the humic acid liquid fertilizer, and the operations well-known to those skilled in the art can be adopted.

[0054] The following is a detailed description of the method for producing a humic acid liquid fertilizer from organic wastewater and its application provided by the present invention in combination with examples, but they cannot be understood as limiting the protection scope of the present invention.

[0055] Examples 1-12 and Comparative Examples 1-4

[0056] Mix food waste wastewater (BOD is 10500 mg / L) and catechol in a reaction kettle. The volume of the food waste wastewater accounts for 70% of the effective volume of the reaction kettle. Adjust the pH value of the obtained mixed system, heat up to the temperature of the hydrothermal reaction, and carry out the hydrothermal reaction under closed conditions to obtain a humic acid liquid fertilizer.

[0057] The method parameters in Examples 1-12 and Comparative Examples 1-4 are shown in Table 1.

[0058] Table 1 Method parameters in Examples 1-12 and Comparative Examples 1-4

[0059] Hydrothermal reaction temperature / °C Hydrothermal reaction time / h pH Catechol addition amount / g / L T1 - Comparative Example 1 160 0.5 5 0 T2 - Example 1 160 1 7 0.5 T3 - Example 2 160 1.5 9 1 T4 - Example 3 160 2 11 1.5 T5 - Example 4 180 0.5 7 1 T6 - Example 5 180 1 5 1.5 T7 - Comparative Example 2 180 1.5 11 0 T8 - Example 6 180 2 9 0.5 T9 - Example 7 200 0.5 9 1.5 T10 - Example 8 200 1 11 1 T11 - Example 9 200 1.5 5 0.5 T12 - Comparative Example 3 200 2 7 0 T13 - Example 10 220 0.5 11 0.5 T14 - Comparative Example 4 220 1 9 0 T15 - Example 11 220 1.5 7 1.5 T16 - Example 12 220 2 5 1

[0060] The content of humic acid in the humic acid liquid fertilizers obtained in Examples 1-12 and Comparative Examples 1-4 was determined by the alkali dissolution and acid precipitation method, and range analysis was carried out. The results are as Figure 1 shown. Figure 1 It is a range analysis result diagram of the humic acid content in the humic acid liquid fertilizers obtained in Examples 1-12 and Comparative Examples 1-4. From Figure 1It can be seen that the hydrothermal reaction temperature and pH have a significant impact on the production of humic acid in the liquid fertilizer containing humic acid. Within a certain range, an increase in temperature and pH is conducive to the improvement of the humic acid component of organic matter in the liquid fertilizer containing humic acid obtained by hydrothermal reaction. As the hydrothermal reaction temperature increases, the production of humic acid in the liquid fertilizer containing humic acid first increases and then decreases, and reaches the maximum value at 200 °C; as the pH increases, the production of humic acid in the liquid fertilizer containing humic acid first increases and then decreases, and reaches the maximum value at pH = 9. The hydrothermal reaction time and the addition amount of catechol have a certain but not obvious impact on the production of humic acid in the liquid fertilizer containing humic acid. As the hydrothermal reaction time prolongs, the production of humic acid in the liquid fertilizer containing humic acid first increases and then decreases, and reaches the maximum value at 1.5 h; as the addition amount of catechol increases, the production of humic acid in the liquid fertilizer containing humic acid increases accordingly.

[0061] The DOM three-dimensional fluorescence spectra of the liquid fertilizers containing humic acid obtained in Examples 1 to 12 and Comparative Examples 1 to 4 were analyzed by a three-dimensional fluorescence spectrophotometer, and the results are as Figure 2 shown; the fluorescence region integration was performed on the DOM three-dimensional fluorescence spectra of the liquid fertilizers containing humic acid obtained in Examples 1 to 12 and Comparative Examples 1 to 4, and the range analysis was performed on the fluorescence region integration, and the results are as Figure 3 shown, Figure 2 is the DOM three-dimensional fluorescence spectra of the liquid fertilizers containing humic acid obtained in Examples 1 to 12 and Comparative Examples 1 to 4, Figure 3 is the range analysis result diagram of the fluorescence region integration of the liquid fertilizers containing humic acid obtained in Examples 1 to 12 and Comparative Examples 1 to 4. It can be seen from Figure 2 and Figure 3 that as the hydrothermal reaction temperature and pH increase, the production of humic acid in the liquid fertilizer containing humic acid obtained after hydrothermal reaction increases, which is similar to the Figure 1 results. Therefore, a higher hydrothermal reaction temperature and pH are conducive to the conversion of organic matter into humic acid.

[0062] According to the results of the range analysis, the hydrothermal reaction temperature = 200 °C, the hydrothermal reaction time = 1.5 h, pH = 9, and the addition amount of catechol = 1.5 g / L would be the hydrothermal reaction parameters with the highest theoretical production of humic acid. However, considering the production of humic acid and cost factors, the hydrothermal process parameters of hydrothermal reaction temperature = 200 °C, hydrothermal reaction time = 0.5 h, pH = 11, and addition amount of catechol = 1 g / L would be more optimal, and its humic acid production is slightly higher than the above-mentioned process parameters with the highest theoretical humic acid production and there is no significant difference. Therefore, the hydrothermal reaction temperature = 200 °C, the hydrothermal reaction time = 0.5 h, pH = 11, and the addition amount of catechol = 1 g / L are the appropriate hydrothermal reaction process parameters.

[0063] Examples 13 to 28

[0064] Mix kitchen waste water (BOD is 10500 mg / L), catechol (the dosage ratio of catechol to kitchen waste water is 1 g / L), and manganese dioxide in a reaction kettle. The volume of the kitchen waste water accounts for 70% of the effective volume of the reaction kettle. After adjusting the pH value of the obtained mixed system to 11, heat it up to 200 °C and carry out a hydrothermal reaction for 0.5 h under closed conditions to obtain a humic acid liquid fertilizer.

[0065] The method parameters in Examples 13 to 28 are shown in Table 2. When the oxygen charging pressure is 0.5 MPa, 1.0 MPa, and 1.5 MPa, the operation is as follows: After adjusting the pH value of the obtained mixed liquid to 11, introduce oxygen into the reaction kettle to discharge the air in the reaction kettle. After the air is completely discharged, close the gas valve on one side of the reaction kettle and continue to charge oxygen until the pressure of the reaction kettle reaches the target pressure. Stop charging oxygen, and then heat up to carry out a hydrothermal reaction.

[0066] Table 2 Method parameters in Examples 13 to 28

[0067] Treatment <![CDATA[MnO 2 Dosage / g / L]]> Oxygen charging pressure / MPa T1 - Example 13 0 0 T2 - Example 14 0 0.5 T3 - Example 15 0 1.0 T4 - Example 16 0 1.5 T5 - Example 17 0.5 0 T6 - Example 18 0.5 0.5 T7 - Example 19 0.5 1.0 T8 - Example 20 0.5 1.5 T9 - Example 21 1.0 0 T10 - Example 22 1.0 0.5 T11 - Example 23 1.0 1.0 T12 - Example 24 1.0 1.5 T13 - Example 25 1.5 0 T14 - Example 26 1.5 0.5 T15 - Example 27 1.5 1.0 T16 - Example 28 1.5 1.5

[0068] The content of humic acid in the humic acid liquid fertilizer obtained in Examples 13 to 28 was determined by the alkali dissolution and acid precipitation method, and a range analysis was carried out. The results are as Figure 4 shown. Figure 4 is a range analysis result diagram of the humic acid content in the humic acid liquid fertilizer obtained in Examples 13 to 28. It can be seen from Figure 4 that as the addition amount of MnO 2 increases, the production amount of humic acid gradually increases; as the O 2 charging pressure increases, the production amount of humic acid first increases and then decreases, and reaches the maximum value when the O 2 charging pressure = 0.5 MPa.

[0069] The DOM three-dimensional fluorescence spectrum of the humic acid liquid fertilizer obtained in Examples 13 to 28 was analyzed by a three-dimensional fluorescence spectrophotometer. The results are as Figure 5 shown; the fluorescence region integration of the DOM three-dimensional fluorescence spectrum of the humic acid liquid fertilizer obtained in Examples 13 to 28 was carried out, and a range analysis was carried out on the fluorescence region integration. The results are as Figure 6 shown, Figure 5 is the DOM three-dimensional fluorescence spectrum of the humic acid liquid fertilizer obtained in Examples 13 to 28, Figure 6 is the range analysis result diagram of the fluorescence region integration of the humic acid liquid fertilizer obtained in Examples 13 to 28. It can be seen from Figure 5 and Figure 6 that as the addition amount of MnO 2 increases, the production amount of humic acid in the humic acid liquid fertilizer obtained by the hydrothermal reaction gradually increases; as the O2 With the increase of the filling pressure, the production of humic acid in the liquid fertilizer containing humic acid obtained by hydrothermal reaction first increases and then decreases, and reaches the maximum value when the filling pressure = 0.5 MPa, which is similar to the result of 2 Figure 4 .

[0070] Combining the production of humic acid and cost factors, the addition amount of MnO 2 = 0.5 g / L and the filling pressure = 0.5 MPa are appropriate parameter schemes for enhancing hydrothermal reaction. 2

[0071] Example 29

[0072] Mix kitchen waste water, catechol (the dosage ratio of catechol to kitchen waste water is 1 g / L) and manganese dioxide (the dosage ratio of manganese dioxide to kitchen waste water is 0.5 g / L) in a reaction kettle. The volume of kitchen waste water accounts for 70% of the effective volume of the reaction kettle. After adjusting the pH value of the obtained mixed system to 11, introduce oxygen into the reaction kettle to discharge the air in the reaction kettle. After the air is discharged completely, close the gas valve on one side of the reaction kettle and continue to fill with oxygen until the pressure of the reaction kettle reaches 0.5 MPa. Stop introducing oxygen, and then heat up to 200 °C and carry out hydrothermal reaction for 0.5 h under closed conditions to obtain a liquid fertilizer containing humic acid.

[0073] Performance test

[0074] Based on the nitrogen, phosphorus and potassium contents in the commercial humic acid water-soluble fertilizer on the market, using the liquid fertilizer containing humic acid obtained in Example 29, the original solution of kitchen waste water, and clean water as raw material liquids, and adding raw materials such as urea, diammonium hydrogen phosphate, and potassium sulfate with good water solubility and relatively low price, prepare hydrothermal fertilizers (prepared from the liquid fertilizer containing humic acid obtained in Example 29), original solution fertilizers, and chemical fertilizers with basically the same nitrogen, phosphorus and potassium contents, and no fertilization as the blank treatment (CK). Among them, the hydrothermal fertilizers are diluted 50 (SR50), 100 (SR100), 200 (SR200), and 400 (SR400) times for application, and the original solution fertilizer (YY200), chemical fertilizer (HF200), and commercial fertilizer (SP200) are diluted 200 times for application as a comparison. Using pakchoi as the potted crop, harvest after growing for about one month, and measure its yield and quality. The results are as Figures 7 - 11 shown.

[0075] Figure 7 is the fresh weight of pakchoi under different fertilization treatments, Figure 8 is the dry weight of pakchoi under different fertilization treatments; it can be seen from Figure 7 and Figure 8 that applying the hydrothermal fertilizer diluted 200 times has the greatest effect on increasing the yield of pakchoi, and significantly increases the fresh weight by 17.8% and the dry weight by 38.1% compared with the chemical fertilizer treatment.​​

[0076] Figure 9 are the SPAD values of pakchoi under different fertilization treatments, Figure 10 are the soluble sugars of pakchoi under different fertilization treatments, Figure 11 are the vitamin C of pakchoi under different fertilization treatments. It can be seen from Figures 9 - 11 the following that diluting the hydrothermal fertilizer by 50 times has the greatest effect on increasing the SPAD value of pakchoi. This may be because the dilution ratio is small and the manganese element content in it is the highest, which is beneficial to the synthesis of chlorophyll. In addition, diluting the hydrothermal fertilizer by 200 times has a significantly higher effect on increasing the SPAD value of pakchoi than the chemical fertilizer treatment, with an increase of about 13.7%. Diluting the hydrothermal fertilizer by 200 times also has a certain effect on increasing the soluble sugar and vitamin C of pakchoi. Compared with the chemical fertilizer treatment, the soluble sugar and vitamin C are significantly increased by 22.9% and 8.5% respectively.

[0077] Therefore, taking kitchen waste water as an example, it has certain application value and economic feasibility to treat high-concentration organic waste water by hydrothermal treatment to make humic acid liquid fertilizer.

[0078] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for producing liquid fertilizer containing humic acid from organic wastewater, characterized in that: The following steps are involved: The organic wastewater and phenolic compounds are mixed and subjected to a hydrothermal reaction under closed conditions to obtain a liquid fertilizer containing humic acid; The phenolic compound is catechol and / or resorcinol.

2. The method according to claim 1, characterized in that The BOD of the organic wastewater is greater than or equal to 10500 mg / L; the organic wastewater includes one or more of kitchen wastewater, livestock and poultry breeding wastewater, slaughtering wastewater and food wastewater.

3. The method according to claim 2, characterized in that The dosage ratio of the phenolic compound to the organic wastewater is 0.01-1.5 g / L.

4. The method according to claim 1, characterized in that: The pH value of the mixed system obtained by mixing is 5-11.

5. The method according to claim 1, characterized in that: The organic wastewater is also mixed with a catalyst; the catalyst includes one or more of manganese dioxide, zinc oxide and iron oxide.

6. The method according to claim 1 or 5, characterized in that: The dosage ratio of the catalyst to the organic wastewater is 0.01-1.5 g / L.

7. The method according to claim 1 or 5, characterized in that: After the mixing and before the hydrothermal reaction, oxygen is charged; the charging pressure of the oxygen is 0.11-1.5 MPa.

8. The method according to claim 1, characterized in that The temperature of the hydrothermal reaction is 160-220° C., and the time is 0.5-2 hours.

9. A humic acid-containing liquid fertilizer obtained by the method according to any one of claims 1 to 8.

10. Use of the humic acid-containing liquid fertilizer according to claim 9 in the field of fertilizers.

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