Municipal wastewater treatment system

Abstract

This application relates to a municipal wastewater treatment system, including an equalization tank, a wastewater treatment tank, and a sedimentation tank. A wastewater treatment agent is added to the wastewater treatment tank. Each liter of wastewater contains the following components: polyacrylamide, pyridine-2,6-dicarboxylic acid dihydrazide, diphenylethanol ketone, a catalyst, EDTA, methanol, sodium carbonate, water, and an inorganic flocculant. This application has the following advantages and effects: polyacrylamide can adsorb suspended particles to form relatively large flocs; the inorganic flocculant promotes colloidal coagulation and precipitation through adhesion, bridging, and cross-linking; pyridine-2,6-dicarboxylic acid dihydrazide and diphenylethanol ketone undergo a condensation reaction, and the resulting product carries many active groups such as pyridine groups, hydrazide groups, and hydroxyl groups. Colloidal and suspended particles can react with polar pyridine and hydroxyl groups to form stable bonds, which helps to form large-volume flocculent precipitates, exhibiting the characteristics of low dosage and strong flocculation ability.

Description

Technical Field

[0001] This application relates to the technical field of wastewater treatment, and in particular to municipal wastewater treatment systems. Background Technology

[0002] In recent years, my country's urbanization has accelerated and environmental protection has become increasingly important. As a result, the discharge standards for urban sewage treatment plants have become more stringent, making it urgent for sewage treatment plants to upgrade and renovate to meet the relevant standards.

[0003] Chinese patent publication number CN114604913A discloses a sewage treatment system, which includes a sewage tank, a filtered water recovery tank, and a filtration device. The filtration device is connected to both the sewage tank and the filtered water recovery tank. The filtration device can extract sewage from the sewage tank, filter it, and then discharge it to the filtered water recovery tank.

[0004] Regarding the aforementioned technologies, the inventors believe that current sewage treatment ponds are ineffective in treating sewage and there is still room for improvement. Summary of the Invention

[0005] In order to improve the wastewater treatment effect, this application provides a municipal wastewater treatment system.

[0006] The municipal wastewater treatment system provided in this application adopts the following technical solution: The municipal wastewater treatment system includes an equalization tank, a wastewater treatment tank, and a sedimentation tank. A wastewater treatment agent is added to the wastewater treatment tank, and each liter of wastewater contains the following components in parts by weight: 30-40 parts polyacrylamide; 12-18 parts of pyridine-2,6-dicarboxylic acid dihydrazide; 3-7 parts phenylethanol ketone; 2-3 parts catalyst; 1-2 EDTA; 10-12 parts methanol; 0.4-0.6 parts sodium carbonate; 15-20 parts water; 1-2 parts inorganic flocculant.

[0007] By adopting the above technical solutions, polyacrylamide, a linear organic polymer, can adsorb suspended particles in water and act as a bridge between particles, causing fine particles to form relatively large flocs and accelerating the sedimentation rate. Inorganic flocculants contain polyhydroxy complex ions, which strongly adsorb colloidal particles and promote colloidal coagulation to form precipitates through adhesion, bridging and cross-linking. Pyridine-2,6-dicarboxylic acid dihydrazide and diphenylethanol ketone undergo a condensation reaction, and the resulting product carries many active groups such as pyridine groups, hydrazide groups and hydroxyl groups, and has a high molecular weight. Colloidal particles and suspended particles can react with polar pyridine groups and hydroxyl groups to form stable bonds, which helps to form large-volume flocculent precipitates. It has the characteristics of low dosage and strong flocculation ability.

[0008] Preferably, the wastewater treatment agent further includes 4-5 parts of modified lignin by weight.

[0009] By adopting the above technical solution, lignin is a non-crystalline three-dimensional network-like natural polymer composed of phenylpropane units linked by ether bonds and carbon-carbon bonds. It has a variety of functional groups such as unsaturated double bonds, hydroxyl groups, and carbonyl groups, and has adsorption properties. The modified lignin has an increased molecular weight and carries polar groups, which has a positive impact on the flocculation effect.

[0010] Preferably, the modified lignin is prepared by dissolving 1-3 parts of 2-fluoro-4-propoxybenzaldehyde and 1-3 parts of 2-amino-4-methoxybenzyl alcohol in 8-10 parts of anhydrous ethanol. After stirring electromagnetically for 5-7 minutes, 3-7 parts of lignin and 2-4 drops of 36% concentrated hydrochloric acid are added. The mixture is stirred for 6-7 hours and allowed to stand at 3-5°C for 1-2 hours. Then, the mixture is filtered. Next, 6-8 parts of 95% ethanol are added, and the mixture is stirred. At 3-5°C, 10% NaHCO3 is added to neutralize the pH to 8-9. The mixture is stirred for 45-55 minutes and allowed to stand. The mixture is then filtered again, washed once with water and once with anhydrous ethanol, and then dried.

[0011] By adopting the above technical solution, the aldehyde group of 2-fluoro-4-propoxybenzaldehyde and the amino group of 2-amino-4-methoxybenzyl alcohol can react with the carbonyl group of lignin under acidic conditions to obtain a polymer product carrying polar carbonyl and alcohol hydroxyl groups, which can easily combine with colloidal particles and improve the flocculation effect. In addition, the product can be further blended with lignin with a highly cross-linked supramolecular structure to form a network macromolecular structure, which also has a high capture and flocculation effect on fine particles, thus improving the effect of wastewater treatment.

[0012] Preferably, the ratio of 2-fluoro-4-propoxybenzaldehyde: 2-amino-4-methoxybenzyl alcohol: lignin by weight is 1:1:3.

[0013] Preferably, the ratio of pyridine-2,6-dicarboxylic acid dihydrazide to diphenylethanol ketone is 3:1 by weight.

[0014] Preferably, the catalyst is phosphotungstic acid.

[0015] Preferably, the inorganic flocculant is polyferric sulfate.

[0016] Preferably, the preparation method of the wastewater treatment agent includes the following steps: pyridine-2,6-dicarboxylic acid dihydrazide and diphenylethanol ketone are refluxed in methanol solvent at room temperature in the presence of a catalyst for 18-20 h; then the temperature is raised to 25-30 °C, sodium carbonate, EDTA, water and inorganic flocculant are added and stirred for 20-25 min, and polyacrylamide is slowly and uniformly added while stirring, and stirring is continued for 20-35 min.

[0017] By adopting the above technical solution, the presence of sodium carbonate can promote the dissolution of EDTA, and the slow and uniform addition of polyacrylamide can avoid the phenomenon of polyacrylamide clumping.

[0018] Preferably, the preparation method of the wastewater treatment agent further includes the following steps: heating to 25-30℃, adding sodium carbonate, EDTA, water, modified lignin and inorganic flocculant and stirring for 20-25 minutes.

[0019] In summary, this application includes the following beneficial technical effects: 1. Polyacrylamide is a linear organic polymer that can adsorb suspended particles in water, acting as a bridge between particles to form larger flocs and accelerate sedimentation. Inorganic flocculants contain polyhydroxy complex ions that strongly adsorb colloidal particles, promoting their coagulation and precipitation through adhesion, bridging, and cross-linking. Pyridine-2,6-dicarboxylic acid dihydrazide and diphenylethanol ketone undergo a condensation reaction, yielding a product carrying numerous active groups such as pyridine, hydrazide, and hydroxyl groups, with a high molecular weight. Colloidal and suspended particles can react with polar pyridine and hydroxyl groups to form stable bonds, contributing to the formation of large-volume flocculent precipitates. This product is characterized by low dosage and strong flocculation ability. 2. Lignin is a non-crystalline three-dimensional network-like natural polymer composed of phenylpropane units linked by ether bonds and carbon-carbon bonds. It has a variety of functional groups such as unsaturated double bonds, hydroxyl groups, and carbonyl groups, and has adsorption properties. Modified lignin has a higher molecular weight and carries polar groups, which has a positive impact on flocculation effect. The aldehyde group of 3,2-fluoro-4-propoxybenzaldehyde and the amino group of 2-amino-4-methoxybenzyl alcohol can react with the carbonyl group of lignin under acidic conditions to obtain a high molecular weight product carrying polar carbonyl and alcohol hydroxyl groups, which can easily combine with colloidal particles and improve the flocculation effect. In addition, the product can be further blended with lignin with a highly cross-linked supramolecular structure to form a network macromolecular structure, which also has a high capture and flocculation effect on fine particles, thus improving the effect of wastewater treatment. Detailed Implementation

[0020] The following provides a further detailed description of this application.

[0021] In this application, polyacrylamide was provided by Gongyi Hongyuan Environmental Protection Technology Co., Ltd.; pyridine-2,6-dicarboxylic acid dihydrazide was provided by Zhengzhou Huiju Chemical Co., Ltd.; polyferric sulfate was provided by Henan Changqi Water Treatment Materials Co., Ltd.; and lignin was provided by Jinan Yuxin Chemical Co., Ltd.

[0022] Unless otherwise specified, all raw materials used in the following embodiments are commercially available. Example

[0023] Example 1 This embodiment discloses a municipal wastewater treatment system, including an equalization tank, a wastewater treatment tank, and a sedimentation tank. A wastewater treatment agent is added to the wastewater treatment tank. Each liter of wastewater contains the following components: polyacrylamide, pyridine-2,6-dicarboxylic acid dihydrazide, diphenylethanol ketone, catalyst, EDTA, methanol, sodium carbonate, water, and inorganic flocculant. The catalyst is phosphotungstic acid, and the inorganic flocculant is polyferric sulfate. The content of each component is shown in Table 1 below.

[0024] The preparation method of the wastewater treatment agent includes the following steps: pyridine-2,6-dicarboxylic acid dihydrazide and diphenylethanol ketone are refluxed in methanol solvent at room temperature in the presence of a catalyst for 18 h; then the temperature is raised to 25 °C, sodium carbonate, EDTA, water and inorganic flocculant are added and stirred for 20 min, and polyacrylamide is slowly and uniformly added while stirring, and stirring is continued for another 20 min.

[0025] Example 2 This embodiment discloses a municipal wastewater treatment system, including an equalization tank, a wastewater treatment tank, and a sedimentation tank. A wastewater treatment agent is added to the wastewater treatment tank. Each liter of wastewater contains the following components: polyacrylamide, pyridine-2,6-dicarboxylic acid dihydrazide, diphenylethanol ketone, catalyst, EDTA, methanol, sodium carbonate, water, and inorganic flocculant. The catalyst is phosphotungstic acid, and the inorganic flocculant is polyferric sulfate. The content of each component is shown in Table 1 below.

[0026] The preparation method of the wastewater treatment agent includes the following steps: pyridine-2,6-dicarboxylic acid dihydrazide and diphenylethanol ketone are refluxed in methanol solvent at room temperature in the presence of a catalyst for 20 h; then the temperature is raised to 30 °C, sodium carbonate, EDTA, water and inorganic flocculant are added and stirred for 25 min, and polyacrylamide is slowly and uniformly added while stirring, and stirring is continued for 35 min.

[0027] Example 3 This embodiment discloses a municipal wastewater treatment system, including an equalization tank, a wastewater treatment tank, and a sedimentation tank. A wastewater treatment agent is added to the wastewater treatment tank. Each liter of wastewater contains the following components: polyacrylamide, pyridine-2,6-dicarboxylic acid dihydrazide, diphenylethanol ketone, catalyst, EDTA, methanol, sodium carbonate, water, and inorganic flocculant. The catalyst is phosphotungstic acid, and the inorganic flocculant is polyferric sulfate. The content of each component is shown in Table 1 below.

[0028] The preparation method of the wastewater treatment agent includes the following steps: pyridine-2,6-dicarboxylic acid dihydrazide and diphenylethanol ketone are refluxed in methanol solvent at room temperature in the presence of a catalyst for 19 h; then the temperature is raised to 28 °C, sodium carbonate, EDTA, water and inorganic flocculant are added and stirred for 23 min, and polyacrylamide is slowly and uniformly added while stirring, and stirring is continued for 30 min.

[0029] Example 4 This embodiment discloses a municipal wastewater treatment system, including an equalization tank, a wastewater treatment tank, and a sedimentation tank. A wastewater treatment agent is added to the wastewater treatment tank. Each liter of wastewater contains the following components: polyacrylamide, pyridine-2,6-dicarboxylic acid dihydrazide, diphenylethanol ketone, catalyst, EDTA, methanol, sodium carbonate, water, inorganic flocculant, and modified lignin. The catalyst is phosphotungstic acid, and the inorganic flocculant is polyferric sulfate. The content of each component is shown in Table 1 below.

[0030] The method for preparing modified lignin is as follows: 1 part of 2-fluoro-4-propoxybenzaldehyde and 1 part of 2-amino-4-methoxybenzyl alcohol are dissolved in 8 parts of anhydrous ethanol. After stirring electromagnetically for 5 min, 3 parts of lignin and 2 drops of 36% concentrated hydrochloric acid are added. Stirring is continued for 6 h, and the mixture is allowed to stand at 3℃ for 1 h. Then, it is filtered. 6 parts of 95% ethanol are added, and the mixture is stirred. 10% NaHCO3 is added at 3℃ to neutralize the pH to 8. Stirring is continued for 45 min, and the mixture is allowed to stand. Then, it is filtered again, washed once with water and once with anhydrous ethanol, and then dried.

[0031] The preparation method of the wastewater treatment agent includes the following steps: pyridine-2,6-dicarboxylic acid dihydrazide and diphenylethanol ketone are refluxed in methanol solvent at room temperature in the presence of a catalyst for 18 h; then the temperature is raised to 25 °C, sodium carbonate, EDTA, water, modified lignin and inorganic flocculant are added and stirred for 20 min, and polyacrylamide is slowly and uniformly added while stirring, and stirring is continued for another 20 min.

[0032] Example 5 This embodiment discloses a municipal wastewater treatment system, including an equalization tank, a wastewater treatment tank, and a sedimentation tank. A wastewater treatment agent is added to the wastewater treatment tank. Each liter of wastewater contains the following components: polyacrylamide, pyridine-2,6-dicarboxylic acid dihydrazide, diphenylethanol ketone, catalyst, EDTA, methanol, sodium carbonate, water, inorganic flocculant, and modified lignin. The catalyst is phosphotungstic acid, and the inorganic flocculant is polyferric sulfate. The content of each component is shown in Table 1 below.

[0033] The method for preparing modified lignin is as follows: 3 parts of 2-fluoro-4-propoxybenzaldehyde and 3 parts of 2-amino-4-methoxybenzyl alcohol are dissolved in 10 parts of anhydrous ethanol. After stirring electromagnetically for 7 min, 7 parts of lignin and 4 drops of 36% concentrated hydrochloric acid are added. Stirring is continued for 7 h, and the mixture is allowed to stand at 5 °C for 2 h. Then, the mixture is filtered, and 8 parts of 95% ethanol are added. The mixture is stirred and 10% NaHCO3 is added at 5 °C to neutralize the pH to 9. After stirring for 55 min, the mixture is allowed to stand, filtered again, washed once with water and once with anhydrous ethanol, and then dried.

[0034] The preparation method of the wastewater treatment agent includes the following steps: pyridine-2,6-dicarboxylic acid dihydrazide and diphenylethanol ketone are refluxed in methanol solvent at room temperature in the presence of a catalyst for 20 h; then the temperature is raised to 30 °C, sodium carbonate, EDTA, water, modified lignin and inorganic flocculant are added and stirred for 25 min, and polyacrylamide is slowly and uniformly added while stirring, and stirring is continued for 35 min.

[0035] Example 6 This embodiment discloses a municipal wastewater treatment system, including an equalization tank, a wastewater treatment tank, and a sedimentation tank. A wastewater treatment agent is added to the wastewater treatment tank. Each liter of wastewater contains the following components: polyacrylamide, pyridine-2,6-dicarboxylic acid dihydrazide, diphenylethanol ketone, catalyst, EDTA, methanol, sodium carbonate, water, inorganic flocculant, and modified lignin. The catalyst is phosphotungstic acid, and the inorganic flocculant is polyferric sulfate. The content of each component is shown in Table 1 below.

[0036] The modified lignin is prepared as follows: 2 parts of 2-fluoro-4-propoxybenzaldehyde and 2 parts of 2-amino-4-methoxybenzyl alcohol are dissolved in 9 parts of anhydrous ethanol. After stirring electromagnetically for 6 min, 4 parts of lignin and 3 drops of 36% concentrated hydrochloric acid are added. Stirring is continued for 6.5 h, and the mixture is allowed to stand at 4 °C for 1.5 h. Then, it is filtered. 7 parts of 95% ethanol are added, and the mixture is stirred. 10% NaHCO3 is added at 4 °C to neutralize the pH to 8. Stirring is continued for 50 min, and the mixture is allowed to stand. Then, it is filtered again, washed once with water and once with anhydrous ethanol, and then dried.

[0037] The preparation method of the wastewater treatment agent includes the following steps: pyridine-2,6-dicarboxylic acid dihydrazide and diphenylethanol ketone are refluxed in methanol solvent at room temperature in the presence of a catalyst for 19 h; then the temperature is raised to 28 °C, sodium carbonate, EDTA, water, modified lignin and inorganic flocculant are added and stirred for 23 min, and polyacrylamide is slowly and uniformly added while stirring, and stirring is continued for 30 min.

[0038] Example 7 The difference from Example 4 is that the modified lignin is replaced with lignin; the content of each component is shown in Table 2 below.

[0039] Example 8 The difference from Example 7 is that 2-fluoro-4-propoxybenzaldehyde is replaced with acetaldehyde, and the contents of each component are shown in Table 2 below.

[0040] Example 9 The difference from Example 7 is that 2-amino-4-methoxybenzyl alcohol is replaced with ethylamine, and the contents of each component are shown in Table 2 below.

[0041] Example 10 The difference from Example 4 is that, by weight ratio, 2-fluoro-4-propoxybenzaldehyde: 2-amino-4-methoxybenzyl alcohol: lignin = 1:1:3, that is, in the preparation method of modified lignin, 2 parts of 2-fluoro-4-propoxybenzaldehyde, 2 parts of 2-amino-4-methoxybenzyl alcohol and 6 parts of lignin are used, and the content of each component is shown in Table 2 below.

[0042] Example 11 The difference from Example 1 is that, by weight ratio, pyridine-2,6-dicarboxylic acid dihydrazide: diphenylethanol ketone = 3:1, and the content of each component is shown in Table 2 below.

[0043] Example 12 The difference from Example 1 is that the catalyst is p-toluenesulfonic acid.

[0044] Example 13 The difference from Example 1 is that the inorganic flocculant is ferric sulfate.

[0045] Comparative Example Comparative Example 1 The difference from Example 1 is that the wastewater treatment agent only includes polyacrylamide, EDTA, methanol, sodium carbonate, water and inorganic flocculant, and the content of each component is shown in Table 1 below.

[0046] Comparative Example 2 The difference from Example 1 is that pyridine-2,6-dicarboxylic acid dihydrazide is replaced with hexanohydrazide.

[0047] Comparative Example 3 The difference from Example 1 is that phenylethanol ketone is replaced with 1-cyclopentyl ethyl ketone.

[0048] Table 1. Component content of Examples 1-6 and Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Polyacrylamide 30 40 35 30 40 35 30 Pyridine-2,6-dicarboxylic acid dihydrazide 12 18 14 12 18 14 / Diphenylethanol ketone 3 7 5 3 7 5 / catalyst 2 3 3 2 3 3 / EDTA 1 2 1 1 2 1 / methanol 10 12 11 10 12 11 10 Sodium carbonate 0.4 0.6 0.5 0.4 0.6 0.5 0.4 water 15 20 18 15 20 18 15 Inorganic flocculants 1 2 2 1 2 2 1 Modified lignin / / / 4 5 4 / Table 2. Component content of Examples 7-11 Example 7 Example 8 Example 9 Example 10 Example 11 Polyacrylamide 30 30 30 30 30 Pyridine-2,6-dicarboxylic acid dihydrazide 12 12 12 12 15 Diphenylethanol ketone 3 3 3 3 5 catalyst 2 2 2 2 2 EDTA 1 1 1 1 1 methanol 10 10 10 10 10 Sodium carbonate 0.4 0.4 0.4 0.4 0.4 water 15 15 15 15 15 Inorganic flocculants 1 1 1 1 1 Modified lignin / lignin 4 4 4 4 4 Performance testing Test method: Wastewater with COD of 100 mg / L was used as the test wastewater to be treated; the wastewater was treated using the wastewater treatment systems of the above examples and comparative examples, and the COD was determined according to the "Methods for Monitoring and Analysis of Water and Wastewater". The lower the COD, the better the wastewater treatment effect; the test results are shown in Table 3 below.

[0049] Table 3 Performance test results of each embodiment and comparative example COD removal rate / % Example 1 95.7 Example 2 96.6 Example 3 96.1 Example 4 98.2 Example 5 99.2 Example 6 98.7 Example 7 96.4 Example 8 97.2 Example 9 97.5 Example 10 98.6 Example 11 96.6 Example 12 95.3 Example 13 95.1 Comparative Example 1 92.2 Comparative Example 2 94.2 Comparative Example 3 94.9 This specific embodiment is merely an explanation of this application and is not intended to limit the scope of protection of this application. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but as long as they are within the scope of the claims of this application, they are protected by patent law.

Claims

1. A municipal wastewater treatment method, comprising an equalization tank, a wastewater treatment tank, and a sedimentation tank, characterized in that: A wastewater treatment agent is added to the wastewater treatment tank. The wastewater treatment agent comprises the following components in parts by weight: 30-40 parts polyacrylamide; 12-18 parts of pyridine-2,6-dicarboxylic acid dihydrazide; 3-7 parts phenylethanol ketone; 2-3 parts catalyst; 1-2 EDTA; 10-12 parts methanol; 0.4-0.6 parts sodium carbonate; 15-20 parts water; 1-2 parts inorganic flocculant; 4-5 parts modified lignin; The method for preparing the modified lignin is as follows: 1-3 parts of 2-fluoro-4-propoxybenzaldehyde and 1-3 parts of 2-amino-4-methoxybenzyl alcohol are dissolved in 8-10 parts of anhydrous ethanol. After electromagnetic stirring for 5-7 minutes, 3-7 parts of lignin and 2-4 drops of 36% concentrated hydrochloric acid are added. Stirring is continued for 6-7 hours. The mixture is allowed to stand at 3-5℃ for 1-2 hours, then filtered. 6-8 parts of 95% ethanol are added, and the mixture is stirred. 10% NaHCO3 is added at 3-5℃ to neutralize the pH to 8-9. Stirring is continued for 45-55 minutes, and the mixture is allowed to stand. After filtration, the mixture is washed once with water and once with anhydrous ethanol, and then dried. The catalyst is phosphotungstic acid; the preparation method of the wastewater treatment agent includes the following steps: pyridine-2,6-dicarboxylic acid dihydrazide and diphenylethanol ketone are refluxed in methanol solvent at room temperature in the presence of the catalyst for 18-20 h; then the temperature is raised to 25-30℃, sodium carbonate, EDTA, water, modified lignin and inorganic flocculant are added and stirred for 20-25 min, and polyacrylamide is slowly and uniformly added while stirring, and stirring is continued for 20-35 min.

2. The municipal wastewater treatment method according to claim 1, characterized in that: The weight ratio of 2-fluoro-4-propoxybenzaldehyde: 2-amino-4-methoxybenzyl alcohol: lignin is 1:1:

3.

3. The municipal wastewater treatment method according to claim 1, characterized in that: The ratio of pyridine-2,6-dicarboxylic acid dihydrazide to diphenylethanol ketone is 3:1 by weight.

4. The municipal wastewater treatment method according to claim 1, characterized in that: The inorganic flocculant is polyferric sulfate.