A rapid coagulant for biochemical sludge rapid sedimentation and a preparation method and application thereof

Abstract

The present application relates to a kind of quick-setting agent for biochemical sludge rapid settlement and its preparation method, application, preparation method includes the following steps: extracting polysaccharide MI in biochemical active sludge as imprint template molecule;Selecting ferrous salt, cobalt nitrate and sodium fluoride are dissolved in water, stirring to form solution A;Selecting imidazole-dicarboxylic acid is dissolved in sodium hydroxide solution, stirring to form solution B;Solution B is added to solution A and reacts, and MOF suspension is obtained;MOF suspension is transferred to the reaction kettle under nitrogen protection, imprint template molecule, crosslinking agent and initiator are added to react, and the reaction mixture is freeze-dried to remove imprint template molecule, and MI-MOF compound with MI vacancy is obtained;MI-MOF compound with MI vacancy is mixed with high molecular polymer, and MI-MOF quick-setting agent is obtained.The quick-setting agent is synergized by MI-MOF compound with MI vacancy and high molecular polymer, and the flocculation of flocculant is greatly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage treatment, and particularly relates to a rapid coagulant for rapid settling of biochemical sludge and a preparation method and application thereof. BACKGROUND

[0002] At present, with the rapid development of society and economy, the treatment capacity of traditional municipal engineering, i.e., sewage treatment plants and municipal pipe networks, is relatively lagging behind, and improving the treatment capacity and effluent quality of existing sewage treatment facilities has become the focus of public attention.

[0003] Sludge bulking and poor settling performance are common problems in sewage treatment plants, and it usually takes a long time to restore the good settling performance of bulking sludge, during which the effluent quality of the water plant is difficult to meet the discharge standard and there is a risk of sludge loss. Therefore, during this process, selecting a suitable flocculant is a key factor affecting the treatment effect and operating cost.

[0004] In practical applications, the macromolecules of high molecular flocculants are easily damaged by external factors, resulting in performance degradation. Traditional inorganic flocculants, such as aluminate and ferrite, often have a problem of excessive flocculant dosage, and easy formation of precipitates and excessive residues in water during operation. Therefore, neither high molecular flocculants nor inorganic flocculants have good flocculation and settling effect on high-concentration bulking sludge, and cannot improve the biochemical treatment capacity of high-concentration bulking sludge. SUMMARY

[0005] In order to solve the above problems in the prior art, the application provides a rapid coagulant for rapid settling of biochemical sludge and a preparation method and application thereof. The technical problems to be solved by the application are solved by the following technical solutions:

[0006] The application provides a preparation method of a rapid coagulant for rapid settling of biochemical sludge, comprising the following steps:

[0007] Extracting polysaccharide MI in biochemical active sludge as a fingerprint template molecule;

[0008] Selecting ferrous salt, cobalt nitrate and sodium fluoride to be dissolved in water to form solution A by stirring;

[0009] Selecting imidazole-dicarboxylic acid to be dissolved in sodium hydroxide solution to form solution B by stirring;

[0010] Adding the solution B into the solution A to react, to obtain a MOF suspension;

[0011] transferring the MOF suspension liquid to a reaction kettle under nitrogen protection, adding the imprint template molecule, a crosslinking agent and an initiator to react, and freeze-drying the reaction mixture to remove the imprint template molecule by washing to obtain an MI-MOF compound with an MI vacancy;

[0012] mixing the MI-MOF compound with the MI vacancy and a high molecular polymer to obtain an MI-MOF quick-setting agent.

[0013] In an embodiment of the present application, polysaccharide MI in biochemical active sludge is extracted as an imprint template molecule, comprising:

[0014] The active sludge in the biochemical tank is washed with water for several times, and the polysaccharide MI is extracted from the washed active sludge by column chromatography to obtain the imprint template molecule.

[0015] In an embodiment of the present application, the polysaccharide MI includes one or more of cellulose and hemicellulose.

[0016] In an embodiment of the present application, the ferrous salt includes one or more of ferrous sulfate and ferrous chloride.

[0017] The molar ratio of the ferrous salt, the cobalt nitrate and the sodium fluoride is 2-8:1:1-3.

[0018] In an embodiment of the present application, the volume ratio of the imidazole-dicarboxylic acid and the sodium hydroxide solution is 2-3:1.

[0019] The pH value of the sodium hydroxide solution is 11-13.

[0020] In an embodiment of the present application, the solution B is added to the solution A to react to obtain a MOF suspension liquid, comprising:

[0021] The solution B is injected into a reactor containing the solution A, stirred at a speed of 500-1000 r / min for 5-20 min to react to obtain a MOF suspension liquid.

[0022] The volume ratio of the solution B and the solution A is 1-2:1.

[0023] In an embodiment of the present application, the MOF suspension liquid is transferred to a reaction kettle under nitrogen protection, the imprint template molecule, a crosslinking agent and an initiator are added to react, and the reaction mixture is freeze-dried to remove the imprint template molecule by washing to obtain an MI-MOF compound with an MI vacancy, comprising:

[0024] The MOF suspension liquid is transferred into a reaction kettle under nitrogen protection, and the imprint template molecule, crosslinking agent and initiator are added, and stirring is carried out at 35-45 DEG C for 12-24h to carry out reaction, so as to obtain a reaction mixture containing the MI-MOF compound; wherein, the mass ratio of the imprint template molecule to the MOF suspension liquid is 1:1, the mass ratio of the crosslinking agent to the MOF suspension liquid is 1:100, and the mass ratio of the initiator to the MOF suspension liquid is 1:100;

[0025] The reaction mixture is placed into a vacuum freeze dryer, and the temperature is controlled at-20~-40 DEG C, and under vacuum state, freeze drying is carried out for 12-24h to obtain a freeze-dried material;

[0026] The freeze-dried material is washed with a mixed solution of methanol and sodium hydroxide to remove the imprint template molecule, so as to obtain the MI-MOF compound with MI vacancy, wherein the volume ratio of methanol and sodium hydroxide solution in the mixed solution of methanol and sodium hydroxide is 9~8:1~2.

[0027] In an embodiment of the present application, the high molecular polymer comprises polyacrylamide.

[0028] Another embodiment of the present application provides a quick coagulant for biochemical sludge rapid sedimentation, which is prepared by the preparation method described in the above embodiment, and the quick coagulant is a mixture of the MI-MOF compound and the high molecular polymer, wherein the MI-MOF compound has MI vacancy, and the MOF structure utilizes iron ions and cobalt ions as metal ion cores of the MOF material.

[0029] Still another embodiment of the present application provides an application of the MI-MOF quick coagulant to flocculation and sedimentation of biochemical active sludge in sewage treatment.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] 1. This invention utilizes polysaccharide molecule MI, which affects the settling performance of biochemical sludge, as an imprinting template molecule. MI is compounded with a metal-organic framework (MOF) structure, followed by washing to remove MI, resulting in MI vacancies in the MI-MOF compound. The MI-MOF compound with MI vacancies then combines with a polymer via a connecting bridge to form a quick-setting agent. In this quick-setting agent, on the one hand, the polymer acts as a flocculant, exhibiting sludge flocculation and settling effects; on the other hand, the MI vacancies in the MI-MOF compound are strongly correlated and can bind to the polysaccharides in activated sludge during the sludge flocculation and settling process, resulting in a strong targeted effect and aiding in the settling process. The MI-MOF compound forms large-particle flocs in activated sludge, thereby improving the sludge's settling and adsorption performance. Simultaneously, the metal-organic framework (MOF) structure in the MI-MOF compound utilizes iron and cobalt ions as the metal ion core of the MOF material, exhibiting stronger adsorption and surface nuclear charge capabilities. This effectively prevents the reverse dissolution of metal ions, ensuring flocculation efficiency. Furthermore, the spatial architecture of iron and cobalt ions makes it easier to combine with conventional polymers, forming higher-performance flocculants. Therefore, the accelerator of this invention significantly enhances the flocculation effect of the flocculant through the synergistic effect of the MI-MOF compound with MI vacancies and the polymer.

[0032] 2. The preparation process of the quick-setting agent for rapid settling of biochemical sludge in this invention is simple, green, and harmless. Attached Figure Description

[0033] Figure 1 This is a schematic flowchart illustrating a method for preparing a rapid coagulant for rapid settling of biochemical sludge, as provided in an embodiment of the present invention. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0035] Please see Figure 1 , Figure 1 This is a schematic flowchart illustrating a method for preparing a rapid coagulant for rapid settling of biochemical sludge, as provided in an embodiment of the present invention.

[0036] This embodiment describes a method for preparing a rapid coagulant for the rapid settling of biochemical sludge, including the following steps:

[0037] S1. Extract polysaccharide MI from biochemical activated sludge as imprint template molecules.

[0038] Specifically, the activated sludge in the biological treatment tank is rinsed with water 2-5 times, and polysaccharide MI is extracted from the rinsed activated sludge using column chromatography to obtain imprinting template molecules. The polysaccharide includes one or more of cellulose and hemicellulose.

[0039] S2, select ferrous salt, cobalt nitrate and sodium fluoride dissolved in water, stirring to form solution A.

[0040] Specifically, the molar ratio of ferrous salt, cobalt nitrate and sodium fluoride is 2-8:1:1-3; the ferrous salt includes one or more of ferrous sulfate and ferrous chloride; the water can be selected from pure water.

[0041] S3, select imidazole-dicarboxylic acid dissolved in sodium hydroxide solution, stirring to form solution B.

[0042] Specifically, the volume ratio of imidazole-dicarboxylic acid to sodium hydroxide solution is 2-3:1, and the pH value of the sodium hydroxide solution is 11-13.

[0043] S4, add solution B to solution A to react to obtain MOF suspension.

[0044] Specifically, solution B is rapidly injected into the reactor of solution A by a syringe at a certain ratio, and is stirred at a speed of 500-1000 r / min for 5-20 min to react, to obtain MOF suspension. The volume ratio of solution B to solution A is 1-2:1.

[0045] In this embodiment, solution B and solution A are rapidly injected and stirred, so that the substances in solution B and solution A are rapidly and fully mixed and contacted, ensuring the reaction of the two.

[0046] S5, transfer the MOF suspension to a reaction kettle under nitrogen protection, add a print template molecule, a crosslinking agent and an initiator to react, and freeze dry the reaction mixture to remove the print template molecule to obtain a MI-MOF compound with MI vacancies.

[0047] Specifically, first, the MOF suspension is transferred to a reaction kettle under nitrogen protection, and a print template molecule, a crosslinking agent and an initiator are added, and stirred at 35-45℃ for 12-24h to react, which introduces sludge surface polysaccharide substances in the process of molecular self-assembly, to obtain a reaction mixture, which contains a MI-MOF compound. The mass ratio of the print template molecule to the MOF suspension is 1:1, the mass ratio of the crosslinking agent to the MOF suspension is 1:100, and the mass ratio of the initiator to the MOF suspension is 1:100. The crosslinking agent includes a polyamine crosslinking agent, such as propylene diamine; the initiator includes one or more of ammonium persulfate and potassium persulfate.

[0048] In this embodiment, the print template molecule contains a hydroxyl group, which forms a MI-MOF with the carboxyl group in the MOF material through polymerization under the action of the crosslinking agent and the initiator.

[0049] Then, the reaction mixture is placed in a vacuum freeze dryer, and the temperature is controlled at -20~ -40℃. The freeze drying is performed under vacuum for 12~24h to obtain a freeze-dried material.

[0050] Finally, the freeze-dried material is washed with a methanol and sodium hydroxide mixed solution to remove the imprint template molecules, thereby obtaining an MI-MOF compound with MI vacancies, wherein the volume ratio of methanol to sodium hydroxide solution (pH 12) in the methanol and sodium hydroxide mixed solution is 9~8:1~2.

[0051] In this embodiment, the methanol and sodium hydroxide mixed solution is an effective solution for cleaning polysaccharide substances. The methanol removes soluble organic matter under the action of sodium hydroxide alkaline washing through the principle of similar compatibility.

[0052] S6, mixing the MI-MOF compound with MI vacancies and a high molecular polymer to obtain a quick-setting agent.

[0053] Specifically, the MI-MOF compound with MI vacancies and the high molecular polymer are physically mixed. The carboxyl groups in the MOF material and the amino groups in the high molecular polymer form covalent bond bridges. The covalent bond bridges serve as connecting bridges to complex the MI-MOF compound and the high molecular polymer, thereby obtaining the quick-setting agent. The high molecular polymer includes but is not limited to polyacrylamide.

[0054] The embodiment also provides a quick-setting agent for rapid settling of biochemical sludge, which is prepared by the above preparation method and is a mixture of an MI-MOF compound and a high molecular polymer. The MI-MOF compound has MI vacancies, and the MOF structure uses iron ions and cobalt ions as metal ion cores of the MOF material.

[0055] The embodiment also provides an application of the above MI-MOF quick-setting agent in flocculation and settling of biochemical active sludge in sewage treatment. The MI-MOF quick-setting agent applied in sewage treatment can improve the settling performance of biochemical active sludge and greatly increase the surface overflow flow rate of the secondary settling tank.

[0056] The embodiment further illustrates the quick-setting agent for rapid settling of biochemical sludge and the preparation method and application thereof through the following embodiments.

[0057] Embodiment one

[0058] A preparation method of a quick-setting agent for rapid settling of biochemical sludge, comprising the steps of:

[0059] S1, selecting activated sludge at the end of the aerobic zone of a problem water plant, washing the activated sludge with clean water for 3 times, and extracting polysaccharide substances MI as imprint template molecules by column chromatography.

[0060] S2, ferrous sulfate, cobalt nitrate and sodium fluoride are weighed according to the molar ratio of 2:1:2, dissolved in pure water, and stirred to form solution A.

[0061] S3, imidazole-dicarboxylic acid and sodium hydroxide solution with pH value of 12 are taken according to the volume ratio of 2:1, and the imidazole-dicarboxylic acid is dissolved in the sodium hydroxide solution to form solution B.

[0062] S4, solution A and solution B are taken according to the volume ratio of 2:3, and solution B is quickly injected into the reactor containing solution A through a syringe. After stirring vigorously for 10 min, a MOF suspension is obtained.

[0063] S5, the MOF suspension is transferred to a reaction kettle under nitrogen protection, and a polysaccharide material MI is added to the reaction kettle, as well as a crosslinking agent propylene diamine and an initiator ammonium persulfate. The mass ratio of MOF suspension, polysaccharide material MI, crosslinking agent propylene diamine and initiator ammonium persulfate is 100:100:1:1, and stirring is carried out at 35℃ for 12h to obtain a reaction mixture containing MI-MOF compound.

[0064] Then, the reaction mixture is placed in a vacuum freeze dryer, and the temperature is controlled at-20℃. After 24h of freeze-drying under vacuum, a freeze-dried material is obtained.

[0065] Finally, the freeze-dried material is washed with a mixture of methanol and sodium hydroxide solution to remove the imprint template molecule, and an MI-MOF compound with MI vacancy is obtained. In the mixture of methanol and sodium hydroxide solution, the volume ratio of methanol and sodium hydroxide solution is 9:1.

[0066] S6, the MI-MOF compound with MI vacancy is mixed with polyacrylamide to obtain a biochemical sludge quick-setting agent.

[0067] In a biochemical sludge mixed solution of a certain sewage treatment plant, the sludge concentration is 5100mg / L, and the sludge settling ratio SV30 is 950. The above-mentioned targeted quick-setting agent is added to the system at a dosage of 10ppm, and under the condition that other conditions remain unchanged, the sludge settling ratio SV30 decreases to 450, and the sludge settling performance is improved by 52.6%.

[0068] Example two

[0069] A preparation method of a quick-setting agent for biochemical sludge rapid settling, comprising the steps of:

[0070] S1, the activated sludge at the end of the aerobic zone of a problem water plant is selected, washed with water for 3 times, and the polysaccharide material MI is extracted as an imprint template molecule by column chromatography.

[0071] S2, ferrous sulfate, cobalt nitrate and sodium fluoride are weighed according to the molar ratio of 4:1:2, dissolved in pure water, and stirred to form solution A.

[0072] S3, take imidazole-dicarboxylic acid and sodium hydroxide solution with pH value of 12 in the volume ratio of 2:1, dissolve imidazole-dicarboxylic acid in sodium hydroxide solution, and stir to form solution B.

[0073] S4, take solution A and solution B in the volume ratio of 1:1, and quickly inject solution B into the reactor containing solution A through a syringe, and stir vigorously for 10 min to obtain a MOF suspension.

[0074] S5, transfer the MOF suspension to a reaction kettle under nitrogen protection, add polysaccharide MI and crosslinking agent propylene diamine and initiator ammonium persulfate to the reaction kettle, and the mass ratio of MOF suspension, polysaccharide MI, crosslinking agent propylene diamine and initiator ammonium persulfate is 100:100:1:1, stir at 40℃ for 18h to obtain a reaction mixture containing MI-MOF compound.

[0075] Then, the reaction mixture is placed in a vacuum freeze dryer, the temperature is controlled at-25℃, and the freeze-dried material is obtained after freeze-drying for 20h under vacuum.

[0076] Finally, the freeze-dried material is washed with a mixture of methanol and sodium hydroxide to remove the imprint template molecule, and an MI-MOF compound with MI vacancy is obtained, wherein the volume ratio of methanol and sodium hydroxide solution in the mixture of methanol and sodium hydroxide is 9:1.

[0077] S6, mix the MI-MOF compound with MI vacancy with polyacrylamide to obtain a biochemical sludge quick-setting agent.

[0078] The sludge concentration in the mixed solution of the biochemical sludge in a certain sewage treatment plant is 7300mg / L, and the sludge settling ratio SV30 is 960. The above targeted quick-setting agent is added to the system at a dosage of 20ppm, and under the condition that other conditions remain unchanged, the sludge settling ratio SV30 decreases to 570, and the sludge settling performance is improved by 40.6%.

[0079] Example three

[0080] A preparation method of a quick-setting agent for rapid settling of biochemical sludge, comprising the steps of:

[0081] S1, select the activated sludge at the end of the aerobic zone of the problem water plant, wash it with water 3 times, and extract polysaccharide MI as an imprint template molecule by column chromatography.

[0082] S2, take ferrous sulfate, cobalt nitrate and sodium fluoride in a molar ratio of 6:1:3, dissolve them in pure water, and stir to form solution A.

[0083] S3, take imidazole-dicarboxylic acid and sodium hydroxide solution with pH value of 13 by volume ratio of 3:1, dissolve imidazole-dicarboxylic acid in sodium hydroxide solution, stir to form solution B.

[0084] S4, take solution A and solution B by volume ratio of 1:1, and quickly inject solution B into the reactor containing solution A through a syringe, stir vigorously for 10 min, and then obtain MOF suspension.

[0085] S5, transfer the MOF suspension to a nitrogen-protected reaction kettle, add polysaccharide MI and crosslinking agent propylene diamine and initiator ammonium persulfate to the reaction kettle, and the mass ratio of MOF suspension, polysaccharide MI, crosslinking agent propylene diamine and initiator ammonium persulfate is 100:100:1:1, stir at 45 DEG C for 24 h, and obtain a reaction mixture containing MI-MOF compound.

[0086] Then, the reaction mixture is placed in a vacuum freeze dryer, the temperature is controlled at-30 DEG C, and the freeze-dried material is obtained after 16 h of freeze-drying under vacuum.

[0087] Finally, the freeze-dried material is washed with a mixture of methanol and sodium hydroxide to remove the imprint template molecule, and an MI-MOF compound with MI vacancy is obtained, wherein the volume ratio of methanol and sodium hydroxide solution in the mixture of methanol and sodium hydroxide is 8:2.

[0088] S6, mix the MI-MOF compound with MI vacancy with polyacrylamide to obtain a biochemical sludge quick-setting agent.

[0089] The sludge concentration in the biochemical sludge mixed solution of a certain sewage treatment plant is 5500 mg / L, the sludge settling ratio SV30 is 720, and the water treatment capacity of the secondary sedimentation tank is 3900 m 3 / h, the above targeted quick-setting agent is added to the system at a dosage of 15 ppm, and under the condition that other conditions remain unchanged, the sludge settling ratio SV30 decreases to 570, and the water treatment capacity of the secondary sedimentation tank is 6200 m 3 / h, the water treatment capacity is increased by 53.8%.

[0090] Example Four

[0091] A preparation method of a quick-setting agent for biochemical sludge rapid settling, comprising the steps of:

[0092] S1, select the activated sludge at the end of the aerobic zone of the problem water plant, wash it with water 3 times, and extract polysaccharide MI as an imprint template molecule by column chromatography.

[0093] S2, take ferrous sulfate, cobalt nitrate and sodium fluoride by molar ratio of 8:1:1, dissolve in pure water, and stir to form solution A.

[0094] S3, take imidazole-dicarboxylic acid and sodium hydroxide solution with pH value of 13 by volume ratio of 3:1, dissolve imidazole-dicarboxylic acid in sodium hydroxide solution, and stir to form solution B.

[0095] S4, take solution A and solution B by volume ratio of 2:1, and quickly inject solution B into the reactor containing solution A through a syringe, and stir vigorously for 10 min to obtain a MOF suspension.

[0096] S5, transfer the MOF suspension to a reaction kettle under nitrogen protection, add polysaccharide MI to the reaction kettle, and add crosslinking agent propylene diamine and initiator ammonium persulfate, the mass ratio of MOF suspension, polysaccharide MI, crosslinking agent propylene diamine and potassium persulfate is 100:100:1:1, stir at 45℃ for 24h to obtain a reaction mixture containing MI-MOF compound.

[0097] Then, the reaction mixture is placed in a vacuum freeze dryer, the temperature is controlled at-40℃, and the freeze-dried material is obtained after freeze-drying for 12h under vacuum.

[0098] Finally, the freeze-dried material is washed with a mixture of methanol and sodium hydroxide solution to remove the imprint template molecule, and an MI-MOF compound with MI vacancy is obtained, wherein the volume ratio of methanol and sodium hydroxide solution in the mixture is 8:2.

[0099] S6, mix the MI-MOF compound with MI vacancy with polyacrylamide to obtain a biochemical sludge quick-setting agent.

[0100] The sludge concentration in the biochemical sludge mixed solution of a certain sewage treatment plant is 4600mg / L, the sludge settling ratio SV30 is 690, and the water treatment capacity of the secondary sedimentation tank is 2083m 3 / h, the target quick-setting agent is added to the system at a dosage of 10ppm, and under the condition that other conditions remain unchanged, the sludge settling ratio SV30 decreases to 450, and the water treatment capacity of the secondary sedimentation tank is 3230m 3 / h, the water treatment capacity is increased by 55.1%.

[0101] The embodiment uses polysaccharide MI affecting the sludge settling performance as a fingerprint template molecule, and after the MI is compounded with a metal organic framework MOF structure and then washed to remove the MI, the MI vacancies are formed in the MI-MOF compound, and the MI-MOF compound with the MI vacancies is compounded with a high polymer through a connecting bridge to form a quick-setting agent; in the quick-setting agent, on the one hand, the high polymer serves as a flocculant and has a sludge flocculation and sedimentation effect; on the other hand, the MI vacancies in the MI-MOF compound have a strong correlation and can be combined with polysaccharides of activated sludge in the sludge flocculation and sedimentation process, and the effect is strong, which helps the activated sludge to form large-size flocs, so as to improve the settling and adsorption performance of the sludge; meanwhile, the metal organic framework MOF structure in the MI-MOF compound uses iron and cobalt ions as metal ion cores of the MOF material, has stronger adsorption and surface nuclear electric capacity, can effectively prevent the reverse dissolution of the metal ions, guarantees the flocculation effect, and the spatial structure of the iron and cobalt ions is also easier to be combined with the conventional high polymer, so that a higher-performance flocculating agent is formed; therefore, the quick-setting agent of the embodiment greatly improves the flocculation effect of the flocculant through the synergistic effect of the MI-MOF compound with the MI vacancies and the high polymer.

[0102] The preparation process of the quick-setting agent for the biochemical sludge rapid settling is simple, green and harmless.

[0103] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in the specification.

[0104] Although the present application is described herein in connection with various embodiments, those skilled in the art will understand and appreciate the disclosure embodiments disclosed can be changed and implemented in other ways during the implementation of the claimed application by referring to the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "one" or "an" does not exclude a plurality. A single processor or other unit can implement several functions listed in the claims. Some measures are recorded in mutually different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0105] The above is further detailed description of the present application in combination with specific preferred embodiments, and cannot be deemed as limitation of the specific implementation of the present application to these descriptions. For those skilled in the art to which the present application belongs, without departing from the concept of the present application, a number of simple deductions or substitutions can be made, and all of them shall be deemed as falling within the protection scope of the present application.

Claims

1. A method for preparing a quick-setting agent for rapid settling of biochemical sludge, characterized in that, Including the following steps: Polysaccharide MI extracted from biochemical activated sludge was used as an imprinting template molecule; Ferrous salt, cobalt nitrate, and sodium fluoride were dissolved in water and stirred to form solution A; Imidazole-dicarboxylic acid was dissolved in sodium hydroxide solution and stirred to form solution B; Solution B is added to solution A to react and obtain MOF suspension; The MOF suspension was transferred to a nitrogen-protected reactor, and the imprinting template molecule, crosslinking agent and initiator were added to carry out the reaction. The reaction mixture was then lyophilized and washed to remove the imprinting template molecule, resulting in an MI-MOF compound with MI vacancies. The MI-MOF compound with MI vacancies is mixed with a polymer to obtain an MI-MOF quick-setting agent; the polymer includes polyacrylamide.

2. The method for preparing the quick-setting agent for rapid settling of biochemical sludge according to claim 1, characterized in that, Polysaccharide MI extracted from biochemically activated sludge was used as an imprinting template molecule, including: The activated sludge in the biochemical tank was rinsed with water several times, and polysaccharide MI was extracted from the rinsed activated sludge using column chromatography to obtain the imprinted template molecule.

3. The method for preparing the quick-setting agent for rapid settling of biochemical sludge according to claim 1, characterized in that, The polysaccharide MI includes one or more of cellulose and hemicellulose.

4. The method for preparing the quick-setting agent for rapid settling of biochemical sludge according to claim 1, characterized in that, The ferrous salt includes one or more of ferrous sulfate and ferrous chloride; The molar ratio of the ferrous salt, the cobalt nitrate, and the sodium fluoride is 2~8:1:1~3.

5. The method for preparing the quick-setting agent for rapid settling of biochemical sludge according to claim 1, characterized in that, The volume ratio of the imidazole-dicarboxylic acid to the sodium hydroxide solution is 2~3:1; The pH value of the sodium hydroxide solution is 11-13.

6. The method for preparing the quick-setting agent for rapid settling of biochemical sludge according to claim 1, characterized in that, Solution B is added to solution A to react and obtain an MOF suspension, comprising: The solution B is injected into the reactor containing solution A, and stirred at a speed of 500~1000 r / min for 5~20 min to carry out the reaction, thereby obtaining a MOF suspension; The volume ratio of solution B to solution A is 1 to 2:

1.

7. The method for preparing the quick-setting agent for rapid settling of biochemical sludge according to claim 1, characterized in that, The MOF suspension was transferred to a nitrogen-protected reactor, and the imprinting template molecules, crosslinking agent, and initiator were added to initiate the reaction. The reaction mixture was then lyophilized and washed to remove the imprinting template molecules, yielding an MI-MOF compound with MI vacancies, comprising: The MOF suspension was transferred to a nitrogen-protected reactor, and the imprinting template molecules, crosslinking agent, and initiator were added. The mixture was stirred at 35-45°C for 12-24 hours to carry out the reaction, thereby obtaining a reaction mixture containing MI-MOF compounds. The mass ratio of the imprinting template molecules to the MOF suspension was 1:1, the mass ratio of the crosslinking agent to the MOF suspension was 1:100, and the mass ratio of the initiator to the MOF suspension was 1:

100. The reaction mixture was placed in a vacuum freeze dryer, and the temperature was controlled at -20~-40℃. Under vacuum, the mixture was freeze-dried for 12~24h to obtain the freeze-dried material. The freeze-dried material is washed with a mixture of methanol and sodium hydroxide to remove the imprinting template molecules, thereby obtaining the MI-MOF compound with MI vacancies, wherein the volume ratio of methanol to sodium hydroxide solution in the methanol-sodium hydroxide mixture is 9~8:1~2.

8. A quick-setting agent for rapid settling of biological sludge, characterized in that, The accelerator is prepared by the preparation method according to any one of claims 1-7, wherein the accelerator is a mixture of MI-MOF compound and polymer, wherein the MI-MOF compound has MI vacancies, and the MOF structure utilizes iron ions and cobalt ions as the metal ion core of the MOF material.

9. An application of the quick-setting agent as described in claim 8 in the flocculation and sedimentation of biochemical activated sludge in wastewater treatment.

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