A sewage treatment method based on micro-flocculation filtration

Abstract

The present invention relates to the technical field of sludge treatment, and discloses a sewage treatment method based on micro-flocculation filtration, comprising the following steps: (1) adding a polyamide-amine carboxyl-linked third-generation dendritic polymer to an aqueous solution containing polyacrylamide to obtain a mixed solution I; (2) adding a polyamide-amine fifth-generation dendritic polymer to water, and then adding a zeolite modified with an auxiliary agent for ultrasonic dispersion to obtain a mixed solution II; (3) adding the mixed solution I and concentrated sulfuric acid to the mixed solution II, heating the mixture for reaction, and then performing reduced pressure distillation and drying to obtain a flocculant; (4) adding the flocculant to the sewage to be treated, adjusting the pH value of the solution to 6.5-7.5, stirring, letting it stand, and then filtering. The present invention combines an organic flocculant with an inorganic flocculant to obtain a flocculant, and uses the flocculant for sewage treatment, thereby ensuring that the flocculant can quickly form stable flocs in complex water quality, accelerating the formation and sedimentation of the flocs, and improving the removal effect of pollutants.

Description

Technical Field

[0001] The present 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), sewage treatment plants are finding it difficult to meet Class A or higher discharge standards relying solely on traditional biological treatment processes. Microflocculation filtration technology, as an advanced treatment process, effectively removes trace pollutants such as fine suspended solids, phosphorus, and heavy metals from sewage through the addition of flocculants, improving effluent water quality. The introduction of microflocculation filtration technology not only enhances pollutant removal but also improves the overall stability of the treatment system, further improving water quality and meeting higher environmental protection requirements.

[0003] Compared to other advanced treatment technologies, such as traditional sedimentation filtration and membrane filtration, microflocculation filtration offers higher removal efficiency and greater economic efficiency. Traditional sedimentation filtration processes have low removal rates for fine suspended matter and trace pollutants. While membrane filtration offers high effluent quality, it carries high equipment investment and maintenance costs, and is prone to membrane fouling. Microflocculation filtration utilizes both physical and chemical processes to effectively remove pollutants such as suspended particles, phosphorus, and heavy metals. It also features simple equipment, stable operation, and low costs, making it particularly suitable for upgrading and renovating small and medium-sized wastewater 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 has become a key means of achieving standard discharge. In recent years, the integration of microflocculation and membrane filtration has been explored. This approach uses highly effective flocculants to efficiently capture micropollutants, and membrane filtration further improves 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:

[0007] The present invention provides a sewage treatment method based on micro-flocculation filtration, comprising the following steps:

[0008] (1) adding a polyamide-amine carboxyl-linked third-generation dendrimer to an aqueous solution containing polyacrylamide to obtain a mixed solution I;

[0009] (2) adding polyamide-amine fifth-generation dendrimer to water, and then adding zeolite modified with an additive and ultrasonically dispersing it to obtain a mixed solution II;

[0010] (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, letting it stand, and then filtering.

[0011] Flocculants used in sewage treatment include inorganic flocculants (such as iron salts and aluminum salts) and organic flocculants (such as polyacrylamide and its derivatives). However, inorganic flocculants alone have drawbacks such as small flocs and slow settling rates. While organic flocculants alone offer advantages such as low dosage and rapid floc settling rates, their removal effectiveness is limited when used alone. Therefore, the flocculant prepared by combining inorganic and organic flocculants in the present invention combines the advantages of both, synergizing to achieve superior flocculation effects and possessing broad application prospects.

[0012] Specifically, polyacrylamide and polyamidoamine dendrimers are both high-molecular-weight polymers with excellent flocculation properties. The structure of polyamidoamine dendrimers radiates outward layer by layer from a central core, with each layer of repeating units connected by amide bonds, forming a dendritic network structure. Their properties vary depending on the number of repeating generations and the terminal functional groups. Polyamidoamine, a third-generation carboxyl-grafted dendrimer, has a typical dendritic structure and a large number of carboxyl groups grafted onto its ends, resulting in excellent water solubility. When mixed with the linear long-chain polyacrylamide, the interaction between the carboxyl and amino groups easily forms a dendritic network entangled within the long molecular chain.

[0013] The polyamide-amine fifth-generation dendritic polymer has a large steric hindrance due to its generation number reaching the fifth generation. The molecule as a whole presents a nano-scale 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 with the zeolite modified by the additive, 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 through the reaction of amino and carboxyl groups, the binding is enhanced 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, 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 (including fine suspended solids). 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.

[0014] Preferably, in step (1), the mass ratio of the polyamide-amine carboxyl-linked third-generation dendrimer 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.

[0015] Preferably, in step (2), the mass concentration of the polyamide-amine fifth-generation dendrimer added to water is 0.05-0.2%.

[0016] 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.

[0017] 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 the auxiliary agent and stirring to react, and then centrifuging to obtain the zeolite modified with the auxiliary agent.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] Preferably, in step (3), the heating reaction is heated to 70-80° C. for 1-2 hours.

[0022] 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.

[0023] Compared with the existing technology, the present invention has the following beneficial effects: by combining organic flocculants such as polyacrylamide and polyamide-amine dendrimers with inorganic flocculants such as zeolite, iron salts and aluminum salts to form molecular chain bridges, 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, and COD. DETAILED DESCRIPTION

[0024] The technical solutions of the present invention are described below with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0025] The sewage treatment method based on micro-flocculation filtration in the present invention comprises the following steps:

[0026] (1) adding a polyamide-amine carboxyl-linked third-generation dendrimer to an aqueous solution containing 0.1-0.5% polyacrylamide at a mass ratio of 20-50:1 to obtain a mixed solution I;

[0027] (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 2g:8-10g:0.5-1.5g:100mL, and then centrifuging to obtain the auxiliary agent-modified zeolite;

[0028] Adding a polyamide-amine fifth-generation dendrimer to water at a mass concentration of 0.05-0.2%; then adding a zeolite modified with an additive and ultrasonically dispersing the mixture for 20-40 minutes, wherein the mass ratio of the zeolite modified with the additive to the polyamide-amine fifth-generation dendrimer is 1:0.04-0.1, to obtain a mixed solution II;

[0029] (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 at a mass ratio of 0.05-0.1% of the 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;

[0030] (4) Add flocculant to the wastewater to be treated at an amount of 50 to 800 mg / L, adjust the pH value of the solution to 6.5 to 7.5, stir thoroughly, let it stand for 0.5 to 4 hours, and then filter.

[0031] In a specific embodiment of the present invention, the average molecular weight of polyacrylamide is 8 million to 12 million.

[0032] 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.

[0033] 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 .

[0034] In a specific embodiment of the present invention, the silane coupling agent is an amino-containing silane coupling agent.

[0035] Example 1

[0036] (1) adding a polyamide-amine carboxyl-linked third-generation dendrimer 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 dendrimer to the polyacrylamide is 30:1, to obtain a mixed solution I;

[0037] (2) Zeolite was added to an ethanol aqueous solution (the volume ratio of ethanol to water was 1:1), and then a silane coupling agent (KH550) was added. After heating and refluxing for 7 hours, an auxiliary agent (ferric chloride) was added and stirred for 40 minutes. The ratio of the amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution added was 2g:8g:0.8g:100mL. After the reaction was completed, the mixture was centrifuged and dried to obtain the auxiliary agent-modified zeolite.

[0038] The polyamide-amine fifth-generation dendrimer was added to water at a mass concentration of 0.1%; then, the additive-modified zeolite was added and ultrasonically dispersed for 30 minutes, with the mass ratio of the additive-modified zeolite to the polyamide-amine fifth-generation dendrimer being 1:0.05, to obtain a mixed solution II;

[0039] (3) Mixed solution II and mixed solution I were mixed in a mass ratio of 1:0.3, and then concentrated sulfuric acid (mass concentration of 98%) with a mass percentage of 0.1% of the mass of mixed solution I was added, and the mixture was heated to 70°C for 2 hours, and then distilled under reduced pressure and dried to obtain a flocculant.

[0040] Example 2

[0041] (1) adding a polyamide-amine carboxyl-linked third-generation dendrimer 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 dendrimer to the polyacrylamide is 40:1, to obtain a mixed solution I;

[0042] (2) Zeolite was added to an ethanol aqueous solution (the volume ratio of ethanol to water was 1:1), and then a silane coupling agent (KH550) was added. After heating and refluxing for 7 hours, an auxiliary agent (ferric sulfate) was added and stirred for 40 minutes. The ratio of the amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution added was 2g:8g:0.8g:100mL. After the reaction was completed, the mixture was centrifuged and dried to obtain the auxiliary agent-modified zeolite.

[0043] The polyamide-amine fifth-generation dendrimer was added to water at a mass concentration of 0.1%; then, the additive-modified zeolite was added and ultrasonically dispersed for 40 minutes, with the mass ratio of the additive-modified zeolite to the polyamide-amine fifth-generation dendrimer being 1:0.07, to obtain a mixed solution II;

[0044] (3) Mixed solution II and mixed solution I were mixed in a mass ratio of 1:0.3, and then concentrated sulfuric acid (mass concentration of 98%) with a mass percentage of 0.1% of the mass of mixed solution I was added, and the mixture was heated to 70°C for 2 hours, and then distilled under reduced pressure and dried to obtain a flocculant.

[0045] Example 3

[0046] (1) adding a polyamide-amine carboxyl-linked third-generation dendrimer 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 dendrimer to the polyacrylamide is 50:1, to obtain a mixed solution I;

[0047] (2) Add zeolite to an ethanol aqueous solution (the volume ratio of ethanol to water is 1:1), then add a silane coupling agent (KH550), heat and reflux for 8 hours, add an auxiliary agent (aluminum sulfate) and stir to react for 60 minutes, wherein the added amount ratio of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution is 2g:10g:1g:100mL; after the reaction is completed, centrifuge and dry to obtain the auxiliary agent-modified zeolite;

[0048] The polyamide-amine fifth-generation dendrimer was added to water at a mass concentration of 0.1%; then, the additive-modified zeolite was added and ultrasonically dispersed for 30 minutes, with the mass ratio of the additive-modified zeolite to the polyamide-amine fifth-generation dendrimer being 1:0.05, to obtain a mixed solution II;

[0049] (3) Mixed solution II and mixed solution I were mixed in a mass ratio of 1:0.3, and then concentrated sulfuric acid (mass concentration of 98%) with a mass percentage of 0.1% of the mass of mixed solution I was added, and the mixture was heated to 70°C for 2 hours, and then distilled under reduced pressure and dried to obtain a flocculant.

[0050] Example 4

[0051] (1) adding a polyamide-amine carboxyl-linked third-generation dendrimer 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 dendrimer to the polyacrylamide is 30:1, to obtain a mixed solution I;

[0052] (2) Zeolite was added to an ethanol aqueous solution (the volume ratio of ethanol to water was 1:1), and then a silane coupling agent (KH550) was added. After heating and refluxing for 8 hours, an auxiliary agent (ferric sulfate) was added and stirred for 60 minutes. The ratio of the amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution added was 2g:10g:1.3g:100mL. After the reaction was completed, the mixture was centrifuged and dried to obtain the auxiliary agent-modified zeolite.

[0053] The polyamide-amine fifth-generation dendrimer was added to water at a mass concentration of 0.1%; then, the additive-modified zeolite was added and ultrasonically dispersed for 30 minutes, with the mass ratio of the additive-modified zeolite to the polyamide-amine fifth-generation dendrimer being 1:0.05, to obtain a mixed solution II;

[0054] (3) Mixed solution II and mixed solution I were mixed in a mass ratio of 1:0.4, and then concentrated sulfuric acid (mass concentration of 98%) with a mass ratio of 0.1% of the mass of mixed solution I was added, and the mixture was heated to 80°C for 1.5 hours, and then distilled under reduced pressure and dried to obtain a flocculant.

[0055] Example 5

[0056] (1) adding a polyamide-amine carboxyl-linked third-generation dendrimer 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 dendrimer to the polyacrylamide is 40:1, to obtain a mixed solution I;

[0057] (2) Zeolite was added to an ethanol aqueous solution (the volume ratio of ethanol to water was 1:1), and then a silane coupling agent (KH550) was added. After heating and refluxing for 7 hours, an auxiliary agent (ferric chloride) was added and stirred for 40 minutes. The ratio of the amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution added was 2g:8g:0.8g:100mL. After the reaction was completed, the mixture was centrifuged and dried to obtain the auxiliary agent-modified zeolite.

[0058] The polyamide-amine fifth-generation dendrimer was added to water at a mass concentration of 0.1%; then, the additive-modified zeolite was added and ultrasonically dispersed for 40 minutes, with the mass ratio of the additive-modified zeolite to the polyamide-amine fifth-generation dendrimer being 1:0.09, to obtain a mixed solution II;

[0059] (3) Mixed solution II and mixed solution I were mixed in a mass ratio of 1:0.2, and then concentrated sulfuric acid (mass concentration of 98%) with a mass percentage of 0.1% of the mass of mixed solution I was added, and the mixture was heated to 70°C for 2 hours, and then distilled under reduced pressure and dried to obtain a flocculant.

[0060] Comparative Example 1

[0061] The difference from Example 1 is that the polyamide-amine carboxyl-linked third-generation dendrimer is not added.

[0062] (1) An aqueous solution containing 0.4% polyacrylamide (average molecular weight of 8 million) was prepared as mixed solution I; (2) zeolite was added to an ethanol aqueous solution (the volume ratio of ethanol to water was 1:1), and then a silane coupling agent (KH550) was added. After heating and refluxing for 7 hours, an auxiliary agent (ferric chloride) was added and stirred for 40 minutes. The ratio of the amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution added was 2g:8g:0.8g:100mL. After the reaction was completed, the mixture was centrifuged and dried to obtain the auxiliary agent-modified zeolite;

[0063] The polyamide-amine fifth-generation dendrimer was added to water at a mass concentration of 0.1%; then, the additive-modified zeolite was added and ultrasonically dispersed for 30 minutes, with the mass ratio of the additive-modified zeolite to the polyamide-amine fifth-generation dendrimer being 1:0.05, to obtain a mixed solution II;

[0064] (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.

[0065] Comparative Example 2

[0066] The difference from Example 1 is that the fifth-generation polyamide-amine dendrimer is not added.

[0067] (1) adding a polyamide-amine carboxyl-linked third-generation dendrimer 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 dendrimer to the polyacrylamide is 30:1, to obtain a mixed solution I;

[0068] (2) Zeolite was added to an ethanol aqueous solution (the volume ratio of ethanol to water was 1:1), and then a silane coupling agent (KH550) was added. After heating and refluxing for 7 hours, an auxiliary agent (ferric chloride) was added and stirred for 40 minutes. The ratio of the amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution added was 2g:8g:0.8g:100mL. After the reaction was completed, the mixture was centrifuged and dried to obtain the auxiliary agent-modified zeolite.

[0069] The zeolite modified with the additive was added into water and ultrasonically dispersed for 30 minutes. The mass ratio of the zeolite modified with the additive to water was 1:50 to obtain a mixed solution II.

[0070] (3) Mixed solution II and mixed solution I were mixed in a mass ratio of 1:0.3, and then concentrated sulfuric acid (mass concentration of 98%) with a mass percentage of 0.1% of the mass of mixed solution I was added, and the mixture was heated to 70°C for 2 hours, and then distilled under reduced pressure and dried to obtain a flocculant.

[0071] Comparative Example 3

[0072] The difference from Example 1 is that the third-generation polyamide-amine dendrimer with carboxyl groups and the fifth-generation polyamide-amine dendrimer are added interchangeably.

[0073] (1) adding a polyamide-amine fifth-generation dendrimer to an aqueous solution containing 0.4% polyacrylamide (average molecular weight of 8 million) at a mass ratio of 30:1 to obtain a mixed solution I;

[0074] (2) Zeolite was added to an ethanol aqueous solution (the volume ratio of ethanol to water was 1:1), and then a silane coupling agent (KH550) was added. After heating and refluxing for 7 hours, an auxiliary agent (ferric chloride) was added and stirred for 40 minutes. The ratio of the amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution added was 2g:8g:0.8g:100mL. After the reaction was completed, the mixture was centrifuged and dried to obtain the auxiliary agent-modified zeolite.

[0075] Adding polyamide-amine carboxyl-linked third-generation dendrimer to water at a mass concentration of 0.1%; then adding additive-modified zeolite and ultrasonically dispersing for 30 minutes; the mass ratio of additive-modified zeolite to polyamide-amine carboxyl-linked third-generation dendrimer is 1:0.05 to obtain mixed solution II;

[0076] (3) Mixed solution II and mixed solution I were mixed in a mass ratio of 1:0.3, and then concentrated sulfuric acid (mass concentration of 98%) with a mass percentage of 0.1% of the mass of mixed solution I was added, and the mixture was heated to 70°C for 2 hours, and then distilled under reduced pressure and dried to obtain a flocculant.

[0077] Comparative Example 4

[0078] The difference from Example 1 is that the amount of the polyamide-amine carboxyl-linked third-generation dendrimer added is too small.

[0079] (1) adding a polyamide-amine carboxyl-linked third-generation dendrimer 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 dendrimer to the polyacrylamide is 10:1, to obtain a mixed solution I;

[0080] (2) Zeolite was added to an ethanol aqueous solution (the volume ratio of ethanol to water was 1:1), and then a silane coupling agent (KH550) was added. After heating and refluxing for 7 hours, an auxiliary agent (ferric chloride) was added and stirred for 40 minutes. The ratio of the amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution added was 2g:8g:0.8g:100mL. After the reaction was completed, the mixture was centrifuged and dried to obtain the auxiliary agent-modified zeolite.

[0081] The polyamide-amine fifth-generation dendrimer was added to water at a mass concentration of 0.1%; then, the additive-modified zeolite was added and ultrasonically dispersed for 30 minutes, with the mass ratio of the additive-modified zeolite to the polyamide-amine fifth-generation dendrimer being 1:0.05, to obtain a mixed solution II;

[0082] (3) Mixed solution II and mixed solution I were mixed in a mass ratio of 1:0.3, and then concentrated sulfuric acid (mass concentration of 98%) with a mass percentage of 0.1% of the mass of mixed solution I was added, and the mixture was heated to 70°C for 2 hours, and then distilled under reduced pressure and dried to obtain a flocculant.

[0083] Comparative Example 5

[0084] The difference from Example 1 is that the amount of mixed solution I added is too small.

[0085] (1) adding a polyamide-amine carboxyl-linked third-generation dendrimer 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 dendrimer to the polyacrylamide is 30:1, to obtain a mixed solution I;

[0086] (2) Zeolite was added to an ethanol aqueous solution (the volume ratio of ethanol to water was 1:1), and then a silane coupling agent (KH550) was added. After heating and refluxing for 7 hours, an auxiliary agent (ferric chloride) was added and stirred for 40 minutes. The ratio of the amount of zeolite, silane coupling agent, auxiliary agent and ethanol aqueous solution added was 2g:8g:0.8g:100mL. After the reaction was completed, the mixture was centrifuged and dried to obtain the auxiliary agent-modified zeolite.

[0087] The polyamide-amine fifth-generation dendrimer was added to water at a mass concentration of 0.1%; then, the additive-modified zeolite was added and ultrasonically dispersed for 30 minutes, with the mass ratio of the additive-modified zeolite to the polyamide-amine fifth-generation dendrimer being 1:0.05, to obtain a mixed solution II;

[0088] (3) Mixing the mixed solution II and the mixed solution I in a mass ratio of 1:0.1, adding concentrated sulfuric acid (mass concentration of 98%) at a mass ratio of 0.1% of the mass of the mixed solution I, heating to 70°C for 2 hours, and then distilling under reduced pressure and drying to obtain a flocculant.

[0089] The water quality of untreated sewage is as follows: TN (total nitrogen): 33mg / L, TP (total phosphorus): 14mg / L, COD: 548mg / L, Cu 2+ :86mg / L, Pb 2+ : 55mg / L. Take 1L of the same batch of samples and put them into containers. Add 10g of flocculants prepared in Examples 1-5 and Comparative Examples 1-5 into the corresponding containers respectively. Adjust the pH value of the solution to 6.5-7.5. Stir thoroughly and let it stand for 1 hour. Then filter. Test the TN, TP, COD, Cu 2+ and Pb 2+ The removal rate was calculated as (initial concentration - concentration after adsorption) / initial concentration. The results are shown in Table 1.

[0090] Table 1

[0091] 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

[0092] As shown in Table 1, the flocculants of the present invention can improve the removal of pollutants such as nitrogen, phosphorus, heavy metals, and COD in wastewater. However, in Comparative Examples 1 and 2, due to the absence of the third-generation polyamide-amine dendrimer with carboxyl groups and the fifth-generation polyamide-amine dendrimer, respectively, the resulting flocculants were unable to form a good three-dimensional network structure, thus failing to achieve a good flocculation effect. In Comparative Example 3, due to the substitution of the third-generation polyamide-amine dendrimer with carboxyl groups and the fifth-generation polyamide-amine dendrimer, although a certain degree of molecular chain bridging was achieved, the molecular chains grafted onto the zeolite surface did not form a stretched three-dimensional network structure, and the structural stability was also reduced, resulting in the inability to quickly form stable flocs, thereby reducing the pollutant removal efficiency. In Comparative Example 4, too little polyamide-amine carboxyl-linked third-generation dendrimer was added, while in Comparative Example 5, too little mixed solution I was added. The mixed solution included polyamide-amine carboxyl-linked third-generation dendrimer and polyacrylamide, which also affected the molecular chain grafting effect on the zeolite surface and thus the pollutant removal rate.

[0093] 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 description 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 sewage treatment method based on micro-flocculation filtration, characterized in that: The steps include: (1) Adding a polyamide-amine carboxyl-linked third-generation dendrimer to an aqueous solution containing polyacrylamide to obtain a mixed solution I; (2) adding a polyamide-amine fifth-generation dendrimer to water, and then adding a zeolite modified with an additive and ultrasonically dispersing the zeolite, wherein the additive is one or more of ferrous sulfate, ferrous chloride, ferric sulfate, ferric chloride, aluminum sulfate, and aluminum chloride, to obtain a mixed solution II; (3) Adding mixed solution I and concentrated sulfuric acid to mixed solution II, heating the mixture to react, 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 and let it stand, and then filter.

2. The sewage treatment method based on micro-flocculation filtration according to claim 1, characterized in that: In step (1), the mass ratio of the polyamide-amine carboxyl-linked third-generation dendrimer 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 dendrimer added to water is 0.05-0.2%.

4. The sewage treatment method based on micro-flocculation 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.

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 zeolite modified with the auxiliary agent includes the following steps: adding the zeolite to an ethanol aqueous solution, then adding a silane coupling agent, heating and refluxing, adding the auxiliary agent and stirring the reaction, and then centrifuging to obtain the zeolite modified with the auxiliary agent.

6. The sewage treatment method based on micro-flocculation filtration according to claim 5, characterized in that: The ratio of the added amounts 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 sewage treatment method based on micro-flocculation filtration according to claim 5, characterized in that: 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.

8. The sewage treatment method based on micro-flocculation 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 sewage treatment method 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.