Sewage treatment method based on micro-flocculation filtration

Abstract

The invention relates to the technical field of sludge treatment, and discloses a sewage treatment method based on micro-flocculation filtration, which comprises the following steps: (1) adding a polyamide-amine carboxyl-grafted three-generation dendrimer into a polyacrylamide-containing aqueous solution to obtain a mixed solution I; (2) adding polyamide-amine fifth-generation dendritic polymer into water, then adding zeolite modified by an auxiliary agent, and carrying out ultrasonic dispersion to obtain a mixed solution II; (3) adding the mixed solution I and concentrated sulfuric acid into the mixed solution II, heating for reaction, and then performing reduced pressure distillation and drying to obtain a flocculating agent; and (4) adding a flocculating agent into the sewage to be treated, adjusting the pH value of the solution to 6.5-7.5, stirring, standing, and filtering. The flocculating agent is obtained by combining an organic flocculating agent and an inorganic flocculating agent, and is used for sewage treatment, so that stable flocs can be quickly formed in complex water quality, the formation and sedimentation of the flocs are accelerated, and the removal effect on pollutants is improved.

Description

Technical Field

[0001] The invention relates to the technical field of sludge treatment, and in particular to a sewage treatment method based on micro-flocculation filtration. Background Art

[0002] With the continuous improvement of sewage discharge standards, especially the increasingly stringent control requirements for pollutants such as total phosphorus, total nitrogen, and suspended solids (SS), it is difficult for sewage treatment plants to reach Class A standards or higher discharge standards by relying solely on traditional biological treatment processes. Micro-flocculation filtration technology, as a deep treatment process, can effectively remove trace pollutants such as fine suspended solids, phosphorus, and heavy metals in sewage through the addition of flocculants, and improve the effluent water quality. By introducing micro-flocculation filtration technology, not only can the removal of pollutants be enhanced, but the overall stability of the treatment system can also be improved, further improving water quality and meeting higher environmental protection requirements.

[0003] Compared with other deep treatment technologies, such as traditional sedimentation filtration and membrane filtration technology, microflocculation filtration technology has higher removal efficiency and economy. The traditional sedimentation filtration process has a low removal rate for fine suspended matter and trace pollutants. Although membrane filtration technology has high effluent quality, its equipment investment and maintenance costs are high, and membrane pollution problems are prone to occur. Microflocculation filtration not only effectively removes suspended particles, phosphorus, heavy metals and other pollutants through the dual effects of physics and chemistry, but also has the characteristics of simple equipment, stable operation and low cost. It is especially suitable for the upgrading and transformation of small and medium-sized sewage treatment plants.

[0004] Microflocculation filtration technology has been widely used in the deep purification stage of the water treatment industry. With the improvement of sewage treatment standards, microflocculation technology has become one of the important means to meet the discharge standards. In recent years, we have gradually explored the combination of microflocculation and membrane filtration technology, using efficient flocculants to achieve efficient capture of micropollutants, and combining membrane filtration to further improve filtration accuracy and water quality stability. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a sewage treatment method based on micro-flocculation filtration. The flocculant prepared by combining inorganic and organic flocculants can combine the advantages of both and synergistically exert a better flocculation effect, ensuring that it can quickly form stable flocs in complex water quality, accelerate the formation and sedimentation of flocs, and improve the removal effect of pollutants such as nitrogen, phosphorus, heavy metals, COD, etc., and has broad application prospects.

[0006] The purpose of the present invention is achieved through the following technical solutions: The present invention provides a sewage treatment method based on micro-flocculation filtration, comprising the following steps: (1) adding a polyamide-amine carboxyl-connected third-generation dendritic polymer to an aqueous solution containing polyacrylamide to obtain a mixed solution I; (2) adding polyamide-amine fifth-generation dendrimer to water, and then adding zeolite modified with an additive and ultrasonically dispersing the mixture to obtain a mixed solution II; (3) Adding mixed solution I and concentrated sulfuric acid to mixed solution II, heating the mixture for reaction, and then distilling under reduced pressure and drying to obtain a flocculant; (4) Adding the flocculant to the wastewater to be treated, adjusting the pH value of the solution to 6.5-7.5, stirring and then letting it stand, and then filtering.

[0007] Flocculants for sewage treatment include inorganic flocculants (such as iron salts, aluminum salts, etc.) and organic flocculants (such as polyacrylamide and its derivatives, etc.). However, a single inorganic flocculant has the disadvantages of small flocs and slow sedimentation rate. Although a single organic flocculant has the characteristics of small dosage and fast floc sedimentation rate, its removal effect is limited when used alone. Therefore, the flocculant prepared by combining inorganic and organic flocculants in the present invention can combine the advantages of both, and can synergistically exert a better flocculation effect, and has a wide range of application prospects.

[0008] Specifically, polyacrylamide and polyamide-amine dendrimers are both high molecular polymers and have good flocculation effects. The structure of polyamide-amine dendrimers is that they radiate outward layer by layer from the central core, and each layer of repeating units is connected by amide bonds to form a dendritic network structure. Its properties vary according to its repeating generation and terminal functional groups. The third-generation polyamide-amine dendrimer with carboxyl grafted has a typical dendritic structure, and a large number of carboxyl groups are grafted at the end, which has good water solubility. When it is mixed with polyacrylamide with a linear long molecular chain, due to the interaction between the carboxyl group and the amino group, it is easy to form a dendritic network entangled structure on the long molecular chain.

[0009] Since the polyamide-amine fifth-generation dendritic polymer has reached the fifth generation, the dendritic macromolecule has a large steric hindrance, the molecule as a whole presents a nanoscale spherical shape, there are cavities in the molecule, and its surface is rich in amino functional groups. These groups give the polymer good hydrophilicity and provide a large number of reaction sites and specific surface area. By combining the polyamide-amine fifth-generation dendritic polymer and the zeolite modified by the auxiliary agent, the porous structure of the zeolite can be embedded in the spherical polymer, and rely on the large number of functional groups on its surface to form interactions and improve the binding strength. Then, the mixture obtained in step (1) and step (2) is combined, and the amino and carboxyl groups react to enhance the binding while forming a bridge to obtain a three-dimensional network structure of long molecular chains and dendritic molecular chains grafted on the zeolite surface. This structure combines the advantages of inorganic flocculants and organic flocculants, and can ensure that it can quickly form stable flocs in complex water quality, accelerate the formation and sedimentation of flocs, and improve the removal effect of pollutants such as nitrogen, phosphorus, heavy metals, COD, etc. (including fine suspended matter). At the same time, the structure of the flocculant also has long-term stability, ensuring that its performance does not change significantly during storage and use.

[0010] Preferably, in step (1), the mass ratio of the polyamide-amine-carboxyl-linked third-generation dendritic polymer to polyacrylamide is 20-50:1; the mass concentration of the aqueous solution containing polyacrylamide is 0.1-0.5%; and the average molecular weight of the polyacrylamide is 8 million to 12 million.

[0011] Preferably, in step (2), the mass concentration of the polyamide-amine fifth-generation dendritic polymer added to water is 0.05-0.2%.

[0012] Preferably, in step (2), the mass ratio of the auxiliary agent-modified zeolite to the polyamide-amine fifth-generation dendrimer is 1:0.04-0.1; and the auxiliary agent is one or more of ferrous sulfate, ferrous chloride, ferric sulfate, ferric chloride, aluminum sulfate and aluminum chloride.

[0013] Preferably, in step (2), the preparation of the zeolite modified with the auxiliary agent comprises the following steps: adding the zeolite to an ethanol aqueous solution, then adding a silane coupling agent, heating to reflux, adding an auxiliary agent and stirring to react, and then centrifuging to obtain the zeolite modified with the auxiliary agent.

[0014] Preferably, the ratio of the added amounts of the zeolite, the silane coupling agent, the auxiliary agent and the ethanol aqueous solution is 2 g: 8-10 g: 0.5-1.5 g: 100 mL.

[0015] Preferably, the volume ratio of ethanol to water in the ethanol aqueous solution is 1:1; and the heating reflux time is 5 to 8 hours.

[0016] Preferably, in step (3), the mass ratio of the mixed solution II to the mixed solution I is 1:0.2-0.4; and the amount of concentrated sulfuric acid added is 0.05-0.1% of the mass of the mixed solution I.

[0017] Preferably, in step (3), the heating reaction is heated to 70-80° C. for 1-2 hours.

[0018] Preferably, in step (4), the amount of the flocculant added is 30 to 800 g / L; and the mixture is allowed to stand for 0.5 to 4 hours after stirring.

[0019] Compared with the prior art, the present invention has the following beneficial effects: by combining organic flocculants such as polyacrylamide and polyamide-amine dendritic polymers and inorganic flocculants such as zeolite, iron salt and aluminum salt to form a molecular chain bridge, a three-dimensional network structure of long molecular chains and dendritic molecular chains grafted onto the zeolite surface is obtained. This structure combines the advantages of inorganic flocculants and organic flocculants, can ensure that it can quickly form stable flocs in complex water quality, accelerate the formation and sedimentation of flocs, and improve the removal effect of pollutants such as nitrogen, phosphorus, heavy metals, COD, etc. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is described below with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0021] The sewage treatment method based on microflocculation filtration in the present invention comprises the following steps: (1) adding a polyamide-amine carboxyl-linked third-generation dendritic polymer to an aqueous solution containing 0.1-0.5% polyacrylamide at a mass ratio of 20-50:1 to obtain a mixed solution I; (2) adding zeolite to an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), then adding a silane coupling agent, heating and refluxing for 5 to 8 hours, adding an auxiliary agent and stirring for 30 to 60 minutes, wherein the ratio of the added amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution is 2 g: 8 to 10 g: 0.5 to 1.5 g: 100 mL, and then centrifuging to obtain an auxiliary-modified zeolite; Adding polyamide-amine fifth-generation dendritic polymer to water, the mass concentration of polyamide-amine fifth-generation dendritic polymer is 0.05-0.2%; then adding zeolite modified by an auxiliary agent and ultrasonically dispersing for 20-40 minutes, the mass ratio of zeolite modified by an auxiliary agent to polyamide-amine fifth-generation dendritic polymer is 1:0.04-0.1, to obtain a mixed solution II; (3) Mixing the mixed solution II and the mixed solution I in a mass ratio of 1:0.2-0.4, adding concentrated sulfuric acid of 0.05-0.1% by mass of the mixed solution I, heating to 70-80° C. for reaction for 1-2 hours, and then distilling under reduced pressure and drying to obtain a flocculant; (4) Add 50 to 800 mg / L of flocculant to the wastewater to be treated, adjust the pH value of the solution to 6.5 to 7.5, stir thoroughly, let stand for 0.5 to 4 hours, and then filter.

[0022] In a specific embodiment of the present invention, the average molecular weight of polyacrylamide is 8 million to 12 million.

[0023] In a specific embodiment of the present invention, the auxiliary agent is one or more of ferrous sulfate, ferrous chloride, ferric sulfate, ferric chloride, aluminum sulfate and aluminum chloride.

[0024] In a specific embodiment of the present invention, the particle size of the zeolite is 0.5 to 3 mm and the density is 2 to 2.6 g / cm 3 .

[0025] In a specific embodiment of the present invention, the silane coupling agent is an amino-containing silane coupling agent.

[0026] Example 1 (1) adding a polyamide-amine carboxyl-linked third-generation dendritic polymer to an aqueous solution containing 0.4% polyacrylamide (average molecular weight of 8 million), wherein the mass ratio of the polyamide-amine carboxyl-linked third-generation dendritic polymer to the polyacrylamide is 30:1, to obtain a mixed solution I; (2) adding zeolite to an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), then adding a silane coupling agent (KH550), heating and refluxing for 7 hours, adding an auxiliary agent (ferric chloride) and stirring for 40 minutes, wherein the ratio of the added amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution is 2g:8g:0.8g:100mL; after the reaction is completed, centrifuging and drying are performed to obtain the zeolite modified with the auxiliary agent; Adding polyamide-amine fifth-generation dendritic polymer into water, the mass concentration of polyamide-amine fifth-generation dendritic polymer is 0.1%; then adding zeolite modified by an auxiliary agent and ultrasonically dispersing for 30 minutes, the mass ratio of zeolite modified by an auxiliary agent to polyamide-amine fifth-generation dendritic polymer is 1:0.05, to obtain mixed solution II; (3) Mixing the mixed solution II and the mixed solution I in a mass ratio of 1:0.3, adding concentrated sulfuric acid (mass concentration of 98%) at 0.1% by mass of the mixed solution I, heating to 70° C. for reaction for 2 h, and then distilling under reduced pressure and drying to obtain a flocculant.

[0027] Example 2 (1) adding a polyamide-amine carboxyl-linked third-generation dendritic polymer to an aqueous solution containing 0.5% polyacrylamide (average molecular weight of 8 million), wherein the mass ratio of the polyamide-amine carboxyl-linked third-generation dendritic polymer to the polyacrylamide is 40:1, to obtain a mixed solution I; (2) adding zeolite to an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), then adding a silane coupling agent (KH550), heating and refluxing for 7 hours, adding an auxiliary agent (ferric sulfate) and stirring for 40 minutes, wherein the ratio of the added amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution is 2g:8g:0.8g:100mL; after the reaction is completed, centrifuging and drying are performed to obtain the zeolite modified with the auxiliary agent; Adding polyamide-amine fifth-generation dendritic polymer into water, the mass concentration of polyamide-amine fifth-generation dendritic polymer is 0.1%; then adding zeolite modified by an auxiliary agent and ultrasonically dispersing for 40 minutes, the mass ratio of zeolite modified by an auxiliary agent to polyamide-amine fifth-generation dendritic polymer is 1:0.07, and obtaining mixed solution II; (3) Mixing the mixed solution II and the mixed solution I in a mass ratio of 1:0.3, adding concentrated sulfuric acid (mass concentration of 98%) at 0.1% by mass of the mixed solution I, heating to 70° C. for reaction for 2 h, and then distilling under reduced pressure and drying to obtain a flocculant.

[0028] Example 3 (1) adding a polyamide-amine carboxyl-linked third-generation dendritic polymer to an aqueous solution containing 0.3% polyacrylamide (average molecular weight of 8 million), wherein the mass ratio of the polyamide-amine carboxyl-linked third-generation dendritic polymer to the polyacrylamide is 50:1, to obtain a mixed solution I; (2) adding zeolite to an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), then adding a silane coupling agent (KH550), heating and refluxing for 8 hours, adding an auxiliary agent (aluminum sulfate) and stirring for 60 minutes, wherein the ratio of the added amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution is 2g:10g:1g:100mL; after the reaction is completed, centrifuging and drying are performed to obtain the zeolite modified with the auxiliary agent; Adding polyamide-amine fifth-generation dendritic polymer into water, the mass concentration of polyamide-amine fifth-generation dendritic polymer is 0.1%; then adding zeolite modified by an auxiliary agent and ultrasonically dispersing for 30 minutes, the mass ratio of zeolite modified by an auxiliary agent to polyamide-amine fifth-generation dendritic polymer is 1:0.05, to obtain mixed solution II; (3) Mixing the mixed solution II and the mixed solution I in a mass ratio of 1:0.3, adding concentrated sulfuric acid (mass concentration of 98%) at 0.1% by mass of the mixed solution I, heating to 70° C. for reaction for 2 h, and then distilling under reduced pressure and drying to obtain a flocculant.

[0029] Example 4 (1) adding a polyamide-amine carboxyl-linked third-generation dendritic polymer to an aqueous solution containing 0.4% polyacrylamide (average molecular weight of 10 million), wherein the mass ratio of the polyamide-amine carboxyl-linked third-generation dendritic polymer to the polyacrylamide is 30:1, to obtain a mixed solution I; (2) adding zeolite to an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), then adding a silane coupling agent (KH550), heating and refluxing for 8 hours, adding an auxiliary agent (ferric sulfate) and stirring for 60 minutes, wherein the ratio of the added amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution is 2g:10g:1.3g:100mL; after the reaction is completed, centrifuging and drying are performed to obtain the zeolite modified with the auxiliary agent; Adding polyamide-amine fifth-generation dendritic polymer into water, the mass concentration of polyamide-amine fifth-generation dendritic polymer is 0.1%; then adding zeolite modified by an auxiliary agent and ultrasonically dispersing for 30 minutes, the mass ratio of zeolite modified by an auxiliary agent to polyamide-amine fifth-generation dendritic polymer is 1:0.05, to obtain mixed solution II; (3) Mixing the mixed solution II and the mixed solution I at a mass ratio of 1:0.4, adding concentrated sulfuric acid (mass concentration of 98%) at a mass % of the mixed solution I, heating to 80° C. for reaction for 1.5 h, and then distilling under reduced pressure and drying to obtain a flocculant.

[0030] Example 5 (1) adding a polyamide-amine carboxyl-linked third-generation dendritic polymer to an aqueous solution containing 0.2% polyacrylamide (average molecular weight of 8 million), wherein the mass ratio of the polyamide-amine carboxyl-linked third-generation dendritic polymer to the polyacrylamide is 40:1, to obtain a mixed solution I; (2) adding zeolite to an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), then adding a silane coupling agent (KH550), heating and refluxing for 7 hours, adding an auxiliary agent (ferric chloride) and stirring for 40 minutes, wherein the ratio of the added amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution is 2g:8g:0.8g:100mL; after the reaction is completed, centrifuging and drying are performed to obtain the zeolite modified with the auxiliary agent; Adding polyamide-amine fifth-generation dendritic polymer into water, the mass concentration of polyamide-amine fifth-generation dendritic polymer is 0.1%; then adding zeolite modified by an auxiliary agent and ultrasonically dispersing for 40 minutes, the mass ratio of zeolite modified by an auxiliary agent to polyamide-amine fifth-generation dendritic polymer is 1:0.09, to obtain mixed solution II; (3) Mixing the mixed solution II and the mixed solution I in a mass ratio of 1:0.2, adding concentrated sulfuric acid (mass concentration of 98%) at 0.1% by mass of the mixed solution I, heating to 70° C. for reaction for 2 h, and then distilling under reduced pressure and drying to obtain a flocculant.

[0031] Comparative Example 1 The difference from Example 1 is that no polyamide-amine carboxyl-connected third-generation dendritic polymer is added.

[0032] (1) An aqueous solution containing 0.4% polyacrylamide (average molecular weight of 8 million) is used as mixed solution I; (2) Zeolite is added to an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), and then a silane coupling agent (KH550) is added, and after heating and refluxing for 7 hours, an auxiliary agent (ferric chloride) is added and stirred for reaction for 40 minutes, wherein the ratio of the added amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution is 2g:8g:0.8g:100mL; after the reaction is completed, the mixture is centrifuged and dried to obtain an auxiliary-modified zeolite; Adding polyamide-amine fifth-generation dendritic polymer into water, the mass concentration of polyamide-amine fifth-generation dendritic polymer is 0.1%; then adding zeolite modified by an auxiliary agent and ultrasonically dispersing for 30 minutes, the mass ratio of zeolite modified by an auxiliary agent to polyamide-amine fifth-generation dendritic polymer is 1:0.05, to obtain mixed solution II; (3) Mixing the mixed solution II and the mixed solution I in a mass ratio of 1:0.3, then distilling under reduced pressure and drying to obtain a flocculant.

[0033] Comparative Example 2 The difference from Example 1 is that no polyamide-amine fifth-generation dendrimer is added.

[0034] (1) adding a polyamide-amine carboxyl-linked third-generation dendritic polymer to an aqueous solution containing 0.4% polyacrylamide (average molecular weight of 8 million), wherein the mass ratio of the polyamide-amine carboxyl-linked third-generation dendritic polymer to the polyacrylamide is 30:1, to obtain a mixed solution I; (2) adding zeolite to an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), then adding a silane coupling agent (KH550), heating and refluxing for 7 hours, adding an auxiliary agent (ferric chloride) and stirring for 40 minutes, wherein the ratio of the added amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution is 2g:8g:0.8g:100mL; after the reaction is completed, centrifuging and drying are performed to obtain the zeolite modified with the auxiliary agent; The zeolite modified with the additive was added into water and ultrasonically dispersed for 30 minutes, and the mass ratio of the zeolite modified with the additive to water was 1:50, to obtain a mixed solution II; (3) Mixing the mixed solution II and the mixed solution I in a mass ratio of 1:0.3, adding concentrated sulfuric acid (mass concentration of 98%) at 0.1% by mass of the mixed solution I, heating to 70° C. for reaction for 2 h, and then distilling under reduced pressure and drying to obtain a flocculant.

[0035] Comparative Example 3 The difference from Example 1 is that the third-generation polyamide-amine dendritic polymer with carboxyl groups and the fifth-generation polyamide-amine dendritic polymer are added in place of each other.

[0036] (1) adding a polyamide-amine fifth-generation dendrimer to an aqueous solution containing 0.4% polyacrylamide (average molecular weight of 8 million), wherein the mass ratio of the polyamide-amine fifth-generation dendrimer to the polyacrylamide is 30:1, to obtain a mixed solution I; (2) adding zeolite to an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), then adding a silane coupling agent (KH550), heating and refluxing for 7 hours, adding an auxiliary agent (ferric chloride) and stirring for 40 minutes, wherein the ratio of the added amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution is 2g:8g:0.8g:100mL; after the reaction is completed, centrifuging and drying are performed to obtain the zeolite modified with the auxiliary agent; Add polyamide-amine carboxyl-connected third-generation dendritic polymer into water, the mass concentration of polyamide-amine carboxyl-connected third-generation dendritic polymer is 0.1%; then add zeolite modified by auxiliary agent and ultrasonically disperse for 30 minutes, the mass ratio of zeolite modified by auxiliary agent to polyamide-amine carboxyl-connected third-generation dendritic polymer is 1:0.05, and obtain mixed solution II; (3) Mixing the mixed solution II and the mixed solution I in a mass ratio of 1:0.3, adding concentrated sulfuric acid (mass concentration of 98%) at 0.1% by mass of the mixed solution I, heating to 70° C. for reaction for 2 h, and then distilling under reduced pressure and drying to obtain a flocculant.

[0037] Comparative Example 4 The difference from Example 1 is that the amount of the polyamide-amine carboxyl-linked third-generation dendritic polymer added is too small.

[0038] (1) adding a polyamide-amine carboxyl-linked third-generation dendritic polymer to an aqueous solution containing 0.4% polyacrylamide (average molecular weight of 8 million), wherein the mass ratio of the polyamide-amine carboxyl-linked third-generation dendritic polymer to the polyacrylamide is 10:1, to obtain a mixed solution I; (2) adding zeolite to an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), then adding a silane coupling agent (KH550), heating and refluxing for 7 hours, adding an auxiliary agent (ferric chloride) and stirring for 40 minutes, wherein the ratio of the added amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution is 2g:8g:0.8g:100mL; after the reaction is completed, centrifuging and drying are performed to obtain the zeolite modified with the auxiliary agent; Adding polyamide-amine fifth-generation dendritic polymer into water, the mass concentration of polyamide-amine fifth-generation dendritic polymer is 0.1%; then adding zeolite modified by an auxiliary agent and ultrasonically dispersing for 30 minutes, the mass ratio of zeolite modified by an auxiliary agent to polyamide-amine fifth-generation dendritic polymer is 1:0.05, to obtain mixed solution II; (3) Mixing the mixed solution II and the mixed solution I in a mass ratio of 1:0.3, adding concentrated sulfuric acid (mass concentration of 98%) at 0.1% by mass of the mixed solution I, heating to 70° C. for reaction for 2 h, and then distilling under reduced pressure and drying to obtain a flocculant.

[0039] Comparative Example 5 The difference from Example 1 is that the amount of mixed solution I added is too small.

[0040] (1) adding a polyamide-amine carboxyl-linked third-generation dendritic polymer to an aqueous solution containing 0.4% polyacrylamide (average molecular weight of 8 million), wherein the mass ratio of the polyamide-amine carboxyl-linked third-generation dendritic polymer to the polyacrylamide is 30:1, to obtain a mixed solution I; (2) adding zeolite to an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), then adding a silane coupling agent (KH550), heating and refluxing for 7 hours, adding an auxiliary agent (ferric chloride) and stirring for 40 minutes, wherein the ratio of the added amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution is 2g:8g:0.8g:100mL; after the reaction is completed, centrifuging and drying are performed to obtain the zeolite modified with the auxiliary agent; Adding polyamide-amine fifth-generation dendritic polymer into water, the mass concentration of polyamide-amine fifth-generation dendritic polymer is 0.1%; then adding zeolite modified by an auxiliary agent and ultrasonically dispersing for 30 minutes, the mass ratio of zeolite modified by an auxiliary agent to polyamide-amine fifth-generation dendritic polymer is 1:0.05, to obtain mixed solution II; (3) Mixing the mixed solution II and the mixed solution I at a mass ratio of 1:0.1, adding concentrated sulfuric acid (mass concentration of 98%) at a mass % of the mixed solution I, heating to 70° C. for reaction for 2 h, and then distilling under reduced pressure and drying to obtain a flocculant.

[0041] The water quality of untreated sewage is as follows: TN (total nitrogen): 33 mg / L, TP (total phosphorus): 14 mg / L, COD: 548 mg / L, Cu 2+ :86mg / L,Pb 2+ : 55mg / L. Take 1L of the same batch of samples and put them into containers, and put 10g of flocculants prepared in Examples 1-5 and Comparative Examples 1-5 into the corresponding containers, adjust the pH value of the solution to 6.5-7.5, stir well, let stand for 1h, and then filter. Test the TN, TP, COD, Cu of the supernatant 2+ and Pb2+ Concentration, calculated removal rate = (initial concentration - concentration after adsorption) / initial concentration, the results are shown in Table 1.

[0042] Table 1 TN / % TP / % COD / % <![CDATA[Cu 2+ / %]]> <![CDATA[Cd 2+ / %]]> Example 1 79.8 72.6 69.4 97.8 94.9 Example 2 81.3 75.1 71.0 98.9 96.4 Example 3 80.7 74.9 72.3 98.1 95.8 Example 4 79.5 73.2 69.8 97.3 95.1 Example 5 78.6 70.3 68.1 97.5 95.7 Comparative Example 1 63.9 54.0 55.2 87.1 83.4 Comparative Example 2 61.4 53.6 58.7 88.2 85.5 Comparative Example 3 65.0 51.3 59.5 89.4 87.2 Comparative Example 4 70.4 62.7 60.6 93.5 91.0 Comparative Example 5 71.5 64.5 62.9 91.7 89.6 As shown in Table 1, the flocculant in the present invention can improve the removal effect of pollutants such as nitrogen, phosphorus, heavy metals, COD, etc. in sewage, while in Comparative Example 1 and Comparative Example 2, since the third-generation dendritic polymer of polyamide-amine connected with carboxyl and the fifth-generation dendritic polymer of polyamide-amine were not added, the flocculants obtained could not form a good three-dimensional network structure, and thus could not obtain a good flocculation effect. In Comparative Example 3, since the third-generation dendritic polymer of polyamide-amine connected with carboxyl and the fifth-generation dendritic polymer of polyamide-amine were added in exchange, although a certain degree of molecular chain bridging could be formed, the molecular chains grafted on the surface of zeolite did not form a stretched three-dimensional network structure, and the stability of the structure would also be reduced, resulting in the inability to quickly form a stable floc, and thus the pollutant removal efficiency was reduced. In Comparative Example 4, too little polyamide-amine carboxyl-linked third-generation dendritic polymer was added, while in Comparative Example 5, too little mixed solution I was added, which included polyamide-amine carboxyl-linked third-generation dendritic polymer and polyacrylamide, which would also affect the molecular chain grafting effect on the zeolite surface, thereby affecting the pollutant removal rate.

[0043] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the specification of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A wastewater treatment method based on microflocculation filtration, characterized in that: The steps include: (1) adding a polyamide-amine carboxyl-connected third-generation dendritic polymer to an aqueous solution containing polyacrylamide to obtain a mixed solution I; (2) adding the fifth generation polyamide-amine dendrimer to water, and then adding the zeolite modified with the additive to perform ultrasonic dispersion to obtain a mixed solution II; (3) Adding mixed solution I and concentrated sulfuric acid to mixed solution II, heating the mixture for reaction, and then distilling under reduced pressure and drying to obtain a flocculant; (4) Add flocculant to the wastewater to be treated, adjust the pH value of the solution to 6.5-7.5, stir, let stand, and then filter.

2. The sewage treatment method based on microflocculation filtration according to claim 1, characterized in that: In step (1), the mass ratio of the polyamide-amine carboxyl-linked third-generation dendritic polymer to polyacrylamide is 20-50:1; the mass concentration of the aqueous solution containing polyacrylamide is 0.1-0.5%; and the average molecular weight of the polyacrylamide is 8 million-12 million.

3. The sewage treatment method based on micro-flocculation filtration according to claim 1 or 2, characterized in that: In step (2), the mass concentration of the polyamide-amine fifth-generation dendritic polymer added to water is 0.05-0.2%.

4. The sewage treatment method based on microflocculation filtration according to claim 1, characterized in that: In step (2), the mass ratio of the auxiliary agent-modified zeolite to the polyamide-amine fifth-generation dendrimer is 1:0.04-0.1; the auxiliary agent is one or more of ferrous sulfate, ferrous chloride, ferric sulfate, ferric chloride, aluminum sulfate and aluminum chloride.

5. The sewage treatment method based on micro-flocculation filtration according to claim 1 or 4, characterized in that: In step (2), the preparation of the auxiliary agent-modified zeolite comprises the following steps: adding zeolite to an ethanol aqueous solution, then adding a silane coupling agent, heating to reflux, adding an auxiliary agent, stirring for reaction, and then centrifuging to obtain the auxiliary agent-modified zeolite.

6. The method for treating sewage based on microflocculation filtration according to claim 5, characterized in that: The added amount ratio of the zeolite, the silane coupling agent, the auxiliary agent and the ethanol aqueous solution is 2g:8-10g:0.5-1.5g:100mL.

7. The method for treating sewage based on microflocculation filtration according to claim 5, characterized in that: The volume ratio of ethanol to water in the ethanol aqueous solution is 1:1; the heating reflux time is 5 to 8 hours.

8. The method for treating sewage based on microflocculation filtration according to claim 1, characterized in that: In step (3), the mass ratio of the mixed solution II to the mixed solution I is 1:0.2-0.4; and the amount of concentrated sulfuric acid added is 0.05-0.1% of the mass of the mixed solution I.

9. The sewage treatment method based on micro-flocculation filtration according to claim 1 or 8, characterized in that: In step (3), the heating reaction is heated to 70-80° C. for 1-2 hours.

10. The method for treating sewage based on micro-flocculation filtration according to claim 1, characterized in that: In step (4), the mixture is allowed to stand for 0.5 to 4 hours after stirring.