Method and system for removing zinc, iron and anionic surfactant in hot galvanizing wastewater

Abstract

The invention provides a method and system for removing zinc, iron and an anionic surfactant in hot galvanizing wastewater, and the method comprises the following steps: sequentially carrying out pH regulation treatment and coagulating sedimentation treatment on the hot galvanizing wastewater to obtain a primary treatment solution; when the hot galvanizing wastewater is subjected to coagulating sedimentation treatment, a modified heavy metal precipitant is added into the hot galvanizing wastewater; conveying the primary treatment liquid to a modified ceramic microfiltration membrane device provided with a modified ceramic microfiltration membrane for microfiltration treatment to obtain secondary treatment liquid; and carrying out pH neutralization treatment on the second-stage treatment liquid to obtain a third-stage treatment liquid. According to the method and the system for removing zinc, iron and the anionic surfactant in the hot galvanizing wastewater provided by the invention, suspended matters, zinc ions, iron ions, the anionic surfactant and other substances in the wastewater can be efficiently removed at the same time; finally, the hot galvanizing wastewater is subjected to pH neutralization treatment, so that the pH value of the obtained three-stage treatment liquid can be in a suitable range, and the discharge standard or recycling requirement can be met.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a method and a system for removing zinc, iron and anionic surfactant from hot-dip galvanizing wastewater. Background Art

[0002] Hot-dip galvanizing wastewater mainly comes from the cleaning process in the hot-dip galvanizing process, and the cleaning wastewater usually contains a large amount of pollutants. The main heavy metal pollutants in hot-dip galvanizing wastewater include zinc ions, which mainly come from the galvanizing treatment on the surface of iron products. In addition, due to the material of the iron products themselves, some iron ions will be brought into the wastewater during the cleaning process. In addition to zinc ions and iron ions, hot-dip galvanizing wastewater also contains trace amounts of other metal ions (such as nickel ions, etc.). At the same time, because the corresponding cleaning agent is used in the pre-treatment of the plated parts, the hot-dip galvanizing wastewater will also contain anionic surfactants.

[0003] However, there is currently no process that can simultaneously remove zinc ions, iron ions and anionic surfactants from hot-dip galvanizing wastewater. Therefore, how to simultaneously remove zinc ions, iron ions and anionic surfactants from hot-dip galvanizing wastewater has increasingly become one of the technical problems that need to be solved urgently by those skilled in the art. Summary of the invention

[0004] The object of the present invention is to provide a method and system for removing zinc, iron and anionic surfactants in hot-dip galvanizing wastewater, so as to solve one or more problems existing in the prior art, such as the lack of a process capable of simultaneously removing zinc ions, iron ions and anionic surfactants in hot-dip galvanizing wastewater.

[0005] To achieve the above object, the present invention is implemented by the following technical scheme: a method for removing zinc, iron and anionic surfactants in hot-dip galvanizing wastewater, comprising:

[0006] The hot-dip galvanizing wastewater is subjected to pH adjustment treatment and coagulation and sedimentation treatment in sequence to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and sedimentation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater;

[0007] The primary treatment liquid is transported to a modified ceramic microfiltration membrane device for microfiltration treatment to obtain a secondary treatment liquid; wherein the modified ceramic microfiltration membrane device is provided with a modified ceramic microfiltration membrane;

[0008] The secondary treatment liquid is subjected to pH neutralization treatment to obtain a tertiary treatment liquid.

[0009] Optionally, the modified heavy metal precipitant is prepared by the following steps: SA1: preparing a calcium chloride solution with a mass fraction of 7% to 13% and a ferric chloride solution with a mass fraction of 16% to 26%, and mixing the calcium chloride solution with the ferric chloride solution in a ratio of 1:1 to obtain a mixed solution; SA2: adding 4 g to 9 g of activated carbon, 1 g to 4 g of diatomaceous earth and 0.4 g to 2.5 g of chitosan per liter of the mixed solution, stirring at a stirring speed of 65 rpm to 75 rpm for 5 minutes to 8 minutes to obtain the modified heavy metal precipitant.

[0010] Optionally, the water quality of the hot-dip galvanizing wastewater before treatment is: total zinc is 556 mg / L to 760 mg / L, total iron is 672 mg / L to 2312 mg / L, anionic surfactant is 17 mg / L to 24 mg / L, and pH is 2 to 4.

[0011] Optionally, the hot-dip galvanizing wastewater is subjected to pH adjustment treatment and coagulation and sedimentation treatment in sequence to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and sedimentation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater, including: conveying the hot-dip galvanizing wastewater to a pH adjustment tank, and adjusting the pH value of the hot-dip galvanizing wastewater to 9-10.5 to obtain pH-adjusted effluent; conveying the pH-adjusted effluent to a dosing sedimentation tank, and adding the modified heavy metal precipitant to the dosing sedimentation tank at a dosage of 687 mg / L-932 mg / L, so that the pH-adjusted effluent undergoes a coagulation and sedimentation reaction with the modified heavy metal precipitant to obtain the primary treatment liquid.

[0012] Optionally, the dosing sedimentation tank includes a dosing zone and a sedimentation zone, the modified heavy metal precipitant is added to the dosing zone, the residence time of the pH-adjusted effluent in the dosing zone is 4 minutes to 6 minutes, and the residence time of the pH-adjusted effluent in the sedimentation zone is 17 minutes to 19 minutes.

[0013] Optionally, an online pH meter and an automatic dosing device are connected to the pH adjusting tank; the automatic dosing device is configured to add sodium hydroxide solution into the pH adjusting tank according to the pH value of the hot-dip galvanizing wastewater monitored by the online pH meter, so that the pH value of the hot-dip galvanizing wastewater is controlled at 9 to 10.5.

[0014] Optionally, the modified ceramic microfiltration membrane is prepared by the following steps: SB1: selecting an alumina ceramic membrane as a support and preparing an ammonium nitrate solution with a mass fraction of 6% to 7%; SB2: soaking the support in the ammonium nitrate solution for 12 minutes to 17 minutes, taking out the support, and washing it 3 to 5 times; SB3: placing the washed support in a heating device, heating it to 450°C to 530°C at a heating rate of 5°C / min to 7°C / min, keeping it at this temperature for 5 to 9 minutes, and then cooling it to room temperature; SB4: preparing an isopropanol aluminum solution with a mass fraction of 45% to 57%, placing it in a reaction vessel, taking out the support, and washing it 3 to 5 times; The support body is immersed in the isopropanol aluminum solution, the reaction container is heated to 79°C to 83°C, and maintained at this temperature for 68 minutes to 85 minutes, 34mL to 52mL of 34% to 45% nitric acid solution is added to each liter of the isopropanol aluminum solution, and the reaction container is maintained at 79°C to 83°C for 45 minutes to 55 minutes, and then the support body is taken out and cooled to room temperature; SB5: the support body is placed in the heating device, heated to 455°C to 467°C at a heating rate of 3°C / min to 5°C / min, maintained at this temperature for 123 minutes to 145 minutes, and then cooled to room temperature to obtain the modified ceramic microfiltration membrane.

[0015] Optionally, the alumina ceramic membrane is tubular, the heating device includes a muffle furnace, and the reaction container includes a reaction kettle.

[0016] Optionally, the water quality of the tertiary treatment liquid is: total zinc is 0.5 mg / L to 1.1 mg / L, total iron is 2 mg / L to 3 mg / L, anionic surfactant is 0.3 mg / L to 0.7 mg / L, and pH is 6 to 8.

[0017] To achieve the above-mentioned purpose, the present invention also provides a system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater, comprising a primary treatment module, a secondary treatment module and a tertiary treatment module arranged in sequence; the primary treatment module is configured to perform pH adjustment treatment and coagulation and sedimentation treatment on the hot-dip galvanizing wastewater in sequence to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and sedimentation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater; the secondary treatment module is configured to transport the primary treatment liquid to a modified ceramic microfiltration membrane device for microfiltration treatment to obtain a secondary treatment liquid; wherein, a modified ceramic microfiltration membrane is arranged in the modified ceramic microfiltration membrane device; the tertiary treatment module is configured to perform pH neutralization treatment on the secondary treatment liquid to obtain a tertiary treatment liquid.

[0018] Compared with the prior art, the method and system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention have the following beneficial effects:

[0019] The method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention comprises: sequentially performing pH adjustment treatment and coagulation and precipitation treatment on the hot-dip galvanizing wastewater to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and precipitation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater; the primary treatment liquid is transported to a modified ceramic microfiltration membrane device for microfiltration treatment to obtain a secondary treatment liquid; wherein, a modified ceramic microfiltration membrane is provided in the modified ceramic microfiltration membrane device; the secondary treatment liquid is subjected to pH neutralization treatment to obtain a tertiary treatment liquid. Thus, the method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention lays a foundation for creating conditions conducive to subsequent coagulation and precipitation treatment by performing pH adjustment treatment on the hot-dip galvanizing wastewater; by adding a modified heavy metal precipitant to the hot-dip galvanizing wastewater for coagulation and precipitation treatment, suspended matter, zinc ions, iron ions, anionic surfactants and other substances in the hot-dip galvanizing wastewater can be preliminarily and effectively removed to obtain a primary treatment liquid. Next, by transporting the primary treatment liquid to a modified ceramic microfiltration membrane device provided with a modified ceramic microfiltration membrane for microfiltration treatment, suspended matter, zinc ions, iron ions, anionic surfactants and other substances in the hot-dip galvanizing wastewater can be further efficiently removed to obtain a secondary treatment liquid. Finally, by performing pH neutralization treatment on the secondary treatment liquid, the pH value of the obtained tertiary treatment liquid can be within an appropriate range, thereby being able to meet emission standards or reuse requirements. The method for removing zinc, iron and anionic surfactants in hot-dip galvanizing wastewater provided by the present invention can simultaneously remove zinc ions, iron ions and anionic surfactants in hot-dip galvanizing wastewater, thereby being able to improve the treatment efficiency of hot-dip galvanizing wastewater and reduce environmental pollution.

[0020] Further, the hot-dip galvanizing wastewater is subjected to pH adjustment treatment and coagulation and sedimentation treatment in sequence to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and sedimentation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater, including: transporting the hot-dip galvanizing wastewater to a pH adjustment tank, and adjusting the pH value of the hot-dip galvanizing wastewater to 9-10.5 to obtain pH-adjusted effluent; transporting the pH-adjusted effluent to a dosing sedimentation tank, and adding the modified heavy metal precipitant to the dosing sedimentation tank at a dosage of 687mg / L-932mg / L, so that the pH-adjusted effluent reacts with the modified heavy metal precipitant to obtain the primary treatment liquid. Therefore, the method for removing zinc, iron and anionic surfactants in hot-dip galvanizing wastewater provided by the present invention can help improve the efficiency of subsequent coagulation and sedimentation treatment by adjusting the pH value of the hot-dip galvanizing wastewater to 9-10.5. By adding modified heavy metal precipitants at a dosage of 687 mg / L to 932 mg / L into the dosing sedimentation tank, the modified heavy metal precipitants can more effectively combine with heavy metal ions such as zinc ions and iron ions in the pH-adjusted effluent to generate precipitates that are more easily settled, thereby enhancing the removal effect of suspended solids, zinc ions and iron ions.

[0021] Since the system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention belongs to the same inventive concept as the method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater described in any of the above items, the system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention at least has all the advantages of the method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention. For the advantages of the system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention, please refer to the relevant description of the beneficial effects of the system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention, which will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of the overall steps of a method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided in Example 1 of the present invention;

[0023] Figure 2 A schematic diagram of a specific process of a method for removing zinc, iron and anionic surfactant from hot-dip galvanizing wastewater provided in Example 1 of the present invention;

[0024] Figure 3 A structural block diagram of a system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided in Example 2 of the present invention;

[0025] The following are the descriptions of the reference numerals:

[0026] 1-primary treatment module, 11-primary water inlet pump, 12-pH adjustment tank, 13-dosing sedimentation tank, 2-secondary treatment module, 21-secondary water inlet pump, 22-modified ceramic microfiltration membrane device, 3-tertiary treatment module, 31-tertiary water inlet pump, 32-pH neutralization tank, 33-drainage pump. DETAILED DESCRIPTION

[0027] The following is a further detailed description of the method and system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater proposed by the present invention in combination with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention. In order to make the purposes, features and advantages of the present invention more obvious and easy to understand, please refer to the accompanying drawings. It should be noted that the structures, proportions, sizes, etc. illustrated in the accompanying drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Any modification of the structure, change in the proportional relationship or adjustment of the size, in the case of the same or similar effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical content disclosed by the present invention. The specific design features of the present invention disclosed herein include, for example, specific dimensions, directions, positions and shapes, which will be determined in part by the specific environment to be applied and used. Furthermore, in the embodiments described below, the same reference numerals may be used in common among different drawings to indicate the same parts or parts having the same functions, and their repeated descriptions may be omitted.

[0028] Embodiment 1

[0029] This embodiment provides a method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater. Figure 1 and Figure 2 , Figure 1 A schematic diagram of the overall steps of the method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided in this embodiment; Figure 2 A schematic diagram of a specific process for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided in this embodiment. Figure 1 and Figure 2 It can be seen that the method comprises:

[0030] S100: sequentially performing pH adjustment treatment and coagulation and sedimentation treatment on the hot-dip galvanizing wastewater to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and sedimentation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater;

[0031] S200: transporting the primary treatment liquid to the modified ceramic microfiltration membrane device 22 for microfiltration treatment to obtain a secondary treatment liquid; wherein the modified ceramic microfiltration membrane device 22 is provided with a modified ceramic microfiltration membrane;

[0032] S300: performing pH neutralization treatment on the secondary treatment liquid to obtain a tertiary treatment liquid.

[0033] Thus, the method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by this embodiment, by pH adjustment treatment of hot-dip galvanizing wastewater, lays the foundation for creating conditions conducive to subsequent coagulation and sedimentation treatment; by adding modified heavy metal precipitant to hot-dip galvanizing wastewater for coagulation and sedimentation treatment, suspended matter, zinc ions, iron ions, anionic surfactants and other substances in hot-dip galvanizing wastewater can be initially and effectively removed to obtain a primary treatment liquid. Then, by transporting the primary treatment liquid to a modified ceramic microfiltration membrane device 22 provided with a modified ceramic microfiltration membrane for microfiltration treatment, suspended matter, zinc ions, iron ions, anionic surfactants and other substances in hot-dip galvanizing wastewater can be further efficiently removed to obtain a secondary treatment liquid. Finally, by pH neutralization treatment of the secondary treatment liquid, the pH value of the obtained tertiary treatment liquid can be within an appropriate range, so that it can meet the emission standard or reuse requirements. The method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention can simultaneously remove zinc ions, iron ions and anionic surfactants in hot-dip galvanizing wastewater, thereby improving the treatment efficiency of hot-dip galvanizing wastewater and reducing environmental pollution.

[0034] Preferably, the modified heavy metal precipitant is prepared by the following steps:

[0035] SA1: preparing a calcium chloride solution with a mass fraction of 7% to 13% and a ferric chloride solution with a mass fraction of 16% to 26%, and mixing the calcium chloride solution with the ferric chloride solution in a ratio of 1:1 to obtain a mixed solution;

[0036] SA2: Add 4 to 9 grams of activated carbon, 1 to 4 grams of diatomaceous earth and 0.4 to 2.5 grams of chitosan per liter of the mixed solution, stir at a stirring speed of 65 to 75 rpm for 5 to 8 minutes to obtain the modified heavy metal precipitant.

[0037] Thus, a modified heavy metal precipitant is prepared according to the above steps, so that the flocculation and precipitation effect of the modified heavy metal precipitant is better, which lays a good foundation for enhancing the removal effect of suspended matter, zinc ions and iron ions.

[0038] For example, in some exemplary embodiments, the water quality characteristics of the hot-dip galvanizing wastewater can be: pH value of 2-4, suspended matter concentration of 1789 mg / L-3421 mg / L, total zinc concentration of 556 mg / L-760 mg / L, total iron concentration of 672 mg / L-2312 mg / L, anionic surfactant concentration of 17 mg / L-24 mg / L.

[0039] Preferably, in step S100, the hot-dip galvanizing wastewater is subjected to pH adjustment treatment and coagulation and precipitation treatment in sequence to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and precipitation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater, including: conveying the hot-dip galvanizing wastewater to a pH adjustment tank 12, and adjusting the pH value of the hot-dip galvanizing wastewater to 9 to 10.5 to obtain pH-adjusted effluent; conveying the pH-adjusted effluent to a dosing precipitation tank 13, and adding the modified heavy metal precipitant to the dosing precipitation tank 13 at a dosage of 687 mg / L to 932 mg / L, so that the pH-adjusted effluent reacts with the modified heavy metal precipitant to obtain the primary treatment liquid. Thus, by adjusting the pH value of the hot-dip galvanizing wastewater to 9 to 10.5, the efficiency of the subsequent coagulation and precipitation treatment can be improved. By adding a modified heavy metal precipitant at a dosage of 687 mg / L to 932 mg / L into the dosing sedimentation tank 13, the modified heavy metal precipitant can more effectively combine with heavy metal ions such as zinc ions and iron ions in the pH-adjusted effluent to generate precipitates that are more easily settled, thereby enhancing the removal effect of suspended matter, zinc ions and iron ions.

[0040] Preferably, an online pH meter (not shown in the figure) and an automatic dosing device (not shown in the figure) are connected to the pH adjustment tank 12. The automatic dosing device is configured to add sodium hydroxide solution to the pH adjustment tank 12 according to the pH value of the hot-dip galvanizing wastewater monitored by the online pH meter, so that the pH value of the hot-dip galvanizing wastewater is controlled within 9 to 10.5. Therefore, the pH value of the hot-dip galvanizing wastewater can be automatically controlled within an appropriate range through the automatic dosing device, which lays a good foundation for improving the wastewater treatment efficiency.

[0041] Exemplarily, in some exemplary embodiments, the dosing sedimentation tank 13 includes a dosing zone and a sedimentation zone, the modified heavy metal precipitant is added to the dosing zone, the residence time of the pH-adjusted effluent in the dosing zone is 4 minutes to 6 minutes, and the residence time of the pH-adjusted effluent in the sedimentation zone is 17 minutes to 19 minutes.

[0042] It should be noted that the water quality of the obtained primary treatment liquid is: total zinc is 34mg / L-51mg / L, total iron is 52mg / L-87mg / L, anionic surfactant is 4mg / L-7mg / L, and pH is 9-10.

[0043] Preferably, the modified ceramic microfiltration membrane is prepared by the following steps:

[0044] SB1: Select an aluminum oxide ceramic membrane as a support and prepare an ammonium nitrate solution with a mass fraction of 6% to 7%;

[0045] SB2: After soaking the support in the ammonium nitrate solution for 12 to 17 minutes, taking out the support and washing it 3 to 5 times;

[0046] SB3: placing the cleaned support into a heating device, heating to 450°C to 530°C at a heating rate of 5°C / min to 7°C / min, maintaining the temperature for 5 to 9 minutes, and then cooling to room temperature;

[0047] SB4: Prepare an aluminum isopropoxide solution with a mass fraction of 45% to 57% and place it in a reaction container, take out the support and immerse it in the aluminum isopropoxide solution, heat the reaction container to 79° C. to 83° C., keep it at this temperature for 68 minutes to 85 minutes, add 34 mL to 52 mL of a nitric acid solution with a mass fraction of 34% to 45% per liter of the aluminum isopropoxide solution, keep the reaction container at 79° C. to 83° C. for 45 minutes to 55 minutes, take out the support, and cool it to room temperature;

[0048] SB5: Place the support body in the heating device, heat to 455°C to 467°C at a heating rate of 3°C / min to 5°C / min, maintain at this temperature for 123 minutes to 145 minutes, and then cool to room temperature to obtain the modified ceramic microfiltration membrane.

[0049] Thus, according to the above steps, the porosity of the modified support can be increased to 46.1% to 48.3%, and the permeability can reach 780L / (m 2 ·h·bar)~876L / (m 2 ·h·bar), which makes the filtration effect of the modified ceramic microfiltration membrane better and lays a good foundation for the efficient removal of residual suspended matter, zinc ions, iron ions, anionic surfactants and other substances in the primary treatment liquid.

[0050] For example, in some exemplary embodiments, the alumina ceramic membrane is in a tubular shape, the heating device may be a muffle furnace, and the reaction container may be a reaction kettle.

[0051] For example, in some exemplary embodiments, the operating pressure of the modified ceramic microfiltration membrane device 22 provided with the modified ceramic microfiltration membrane may be 0.12 MPa, the filtration pore size may be 0.24 μm, and the cross-flow velocity may be 2.4 m / s.

[0052] It should be noted that the water quality of the obtained secondary treatment liquid is: total zinc is 0.5mg / L~1.1mg / L, total iron is 2mg / L~3mg / L, anionic surfactant is 0.3mg / L~0.7mg / L, and pH is 9~10.

[0053] Further, the step S300 of performing pH neutralization treatment on the secondary treatment liquid to obtain a tertiary treatment liquid includes: conveying the secondary treatment liquid to a pH neutralization tank 32, and adjusting the pH value of the secondary treatment liquid to 6-8 to obtain a tertiary treatment liquid.

[0054] Preferably, the pH neutralization tank 32 is also connected to the online pH meter and the automatic dosing device. The automatic dosing device is further configured to add hydrochloric acid solution to the pH neutralization tank 32 according to the pH value of the secondary treatment liquid monitored by the online pH meter, so that the pH value of the secondary treatment liquid is controlled at 6 to 8 to obtain a tertiary treatment liquid. Thus, the pH value of the secondary treatment liquid can be automatically controlled within an appropriate range by the automatic dosing device, so that the tertiary treatment liquid can meet the emission standards and reduce environmental pollution.

[0055] It should be noted that the water quality of the obtained tertiary treatment liquid is: total zinc is 0.5mg / L~1.1mg / L, total iron is 2mg / L~3mg / L, anionic surfactant is 0.3mg / L~0.7mg / L, and pH is 6~8.

[0056] In order to make the present invention more understandable, the process of treating hot-dip galvanizing wastewater by using the method for removing zinc, iron and anionic surfactant in hot-dip galvanizing wastewater provided in this embodiment is described by way of example.

[0057] In this example, the water quality characteristics of the hot-dip galvanizing wastewater are as follows: pH value is 2-4, suspended solids concentration is 1789mg / L-3421mg / L, total zinc concentration is 556mg / L-760mg / L, total iron concentration is 672mg / L-2312mg / L, anionic surfactant concentration is 17mg / L-24mg / L. The treatment steps of the hot-dip galvanizing wastewater are as follows:

[0058] First, the hot-dip galvanizing wastewater enters the pH regulating tank 12 through the primary water inlet pump 11. The automatic dosing device adds a sodium hydroxide solution with a mass fraction of 15% to 23% to the pH regulating tank 12 according to the pH value of the hot-dip galvanizing wastewater monitored by the online pH meter, and controls the pH value of the hot-dip galvanizing wastewater to 9 to 10.5. At the same time, the mechanical agitator in the pH regulating tank 12 continuously stirs at a stirring speed of 55 rpm to 75 rpm. After the hot-dip galvanizing wastewater stays in the pH regulating tank 12 for 3 to 5 minutes, pH-adjusted effluent is obtained.

[0059] Then, the pH-adjusted effluent is allowed to flow into the dosing area of ​​the dosing sedimentation tank 13 by gravity, and 687mg / L to 932mg / L of modified heavy metal precipitant is added to the dosing area. At the same time, the mechanical agitator in the dosing area is continuously stirred at a stirring speed of 55 rpm to 85 rpm. The pH-adjusted effluent enters the precipitation area after staying in the dosing area for 4 to 6 minutes, and after staying in the precipitation area for 17 to 19 minutes, a primary treatment liquid is obtained. Specifically, the pH value of the primary treatment liquid is 9 to 10, the suspended matter concentration is 34mg / L to 67mg / L, the total zinc concentration is 34mg / L to 51mg / L, the total iron concentration is 52mg / L to 87mg / L, and the anionic surfactant concentration is 4mg / L to 7mg / L.

[0060] Specifically, in this example, the modified heavy metal precipitant is prepared by the following steps: preparing a calcium chloride solution with a mass fraction of 7% to 13% and a ferric chloride solution with a mass fraction of 16% to 26%, and mixing the calcium chloride solution with the ferric chloride solution in a ratio of 1:1 to obtain a mixed solution; adding 4 g to 9 g of activated carbon, 1 g to 4 g of diatomaceous earth and 0.4 g to 2.5 g of chitosan per liter of the mixed solution, stirring at a stirring speed of 65 rpm to 75 rpm for 5 minutes to 8 minutes to obtain the modified heavy metal precipitant.

[0061] Next, the primary treatment liquid enters the modified ceramic microfiltration membrane device 22 provided with a modified ceramic microfiltration membrane through the secondary water inlet pump 21 for microfiltration treatment to obtain the secondary treatment liquid. Among them, the operating pressure of the modified ceramic microfiltration membrane device 22 is 0.12MPa, the filtration pore size is 0.24μm, and the cross flow velocity is 2.4m / s. The pH value of the secondary treatment liquid is 9-10, the suspended matter concentration is 3mg / L-5mg / L, the total zinc concentration is 0.5mg / L-1.1mg / L, the total iron concentration is 2mg / L-3mg / L, and the anionic surfactant concentration is 0.3mg / L-0.7mg / L.

[0062] More specifically, the modified ceramic microfiltration membrane is prepared by the following steps: selecting a tubular alumina ceramic membrane as a support, and preparing an ammonium nitrate solution with a mass fraction of 6% to 7%; soaking the support in the ammonium nitrate solution for 12 minutes to 17 minutes, taking out the support, and washing it with clean water for 3 to 5 times; placing the washed support in a muffle furnace for roasting, heating it to 450°C to 530°C at a heating rate of 5°C / min to 7°C / min, keeping it at this temperature for 5 minutes to 9 minutes, and cooling it to room temperature; preparing an aluminum isopropoxide solution with a mass fraction of 45% to 57%, placing it in a reactor, taking out the support, and washing it with clean water for 3 to 5 times; The support is immersed in an aluminum isopropoxide solution, the reactor is heated to 79°C to 83°C, and after being kept at this temperature for 68 minutes to 85 minutes, 34mL to 52mL of a nitric acid solution with a mass fraction of 34% to 45% is added to each liter of aluminum isopropoxide solution, and the reactor is kept at 79°C to 83°C for 45 minutes to 55 minutes, the support is taken out, and cooled to room temperature; the support is placed in a muffle furnace for calcination, and heated to 455°C to 467°C at a heating rate of 3°C / min to 5°C / min, and after being kept at this temperature for 123 minutes to 145 minutes, it is cooled to room temperature to obtain the modified ceramic microfiltration membrane. The porosity of the modified support increases to 46.1% to 48.3%, and the permeability reaches 780L / (m 2 ·h·bar)~876L / (m 2 ·h·bar).

[0063] Finally, the secondary treatment liquid enters the pH neutralization tank 32 through the tertiary water inlet pump 31. The automatic dosing device adds a hydrochloric acid solution with a mass fraction of 24% to 27% to the pH neutralization tank 32 according to the pH value of the secondary treatment liquid monitored by the online pH meter, and controls the pH value of the secondary treatment liquid to 6 to 8. After the secondary treatment liquid stays in the pH neutralization tank 32 for 3 to 5 minutes, the tertiary treatment liquid is obtained, and the tertiary treatment liquid is discharged through the drainage pump 33. The pH value of the tertiary treatment liquid is 6 to 8, the suspended solids concentration is 3 mg / L to 5 mg / L, the total zinc concentration is 0.5 mg / L to 1.1 mg / L, the total iron concentration is 2 mg / L to 3 mg / L, and the anionic surfactant concentration is 0.3 mg / L to 0.7 mg / L. It can be seen that the tertiary treatment liquid meets the discharge standard or reuse requirements and can be directly discharged or transported to the near-zero discharge system of wastewater.

[0064] Therefore, the method for removing zinc, iron and anionic surfactants in hot-dip galvanizing wastewater provided by the present invention is used to treat hot-dip galvanizing wastewater, which can effectively remove suspended matter, zinc ions, iron ions and anionic surfactants in the hot-dip galvanizing wastewater.

[0065] In order to facilitate further understanding of the present invention, the present invention is described below with two specific examples of treating hot-dip galvanizing wastewater using the method for removing zinc, iron and anionic surfactant in hot-dip galvanizing wastewater provided by the present invention.

[0066] Example 1: The water quality characteristics of the hot-dip galvanizing wastewater are: pH value is 2.5, suspended solids concentration is 2017 mg / L, total zinc concentration is 624 mg / L, total iron concentration is 875 mg / L, and anionic surfactant concentration is 18 mg / L. The treatment steps for the hot-dip galvanizing wastewater are as follows:

[0067] First, the hot-dip galvanizing wastewater enters the pH adjustment tank 12 through the primary water inlet pump 11. The automatic dosing device adds a 16% sodium hydroxide solution to the pH adjustment tank 12 according to the pH value of the hot-dip galvanizing wastewater monitored by the online pH meter, and controls the pH value of the hot-dip galvanizing wastewater to 9-10.5. At the same time, the mechanical stirrer in the pH adjustment tank 12 continuously stirs at a stirring speed of 59 rpm. After the hot-dip galvanizing wastewater stays in the pH adjustment tank 12 for 4 minutes, pH-adjusted effluent is obtained.

[0068] Then, the pH-adjusted effluent is allowed to flow into the dosing area of ​​the dosing sedimentation tank 13 by gravity, and 725 mg / L of modified heavy metal precipitant is added to the dosing area. At the same time, the mechanical stirrer in the dosing area is continuously stirred at a stirring speed of 65 rpm. The pH-adjusted effluent enters the precipitation area after staying in the dosing area for 5 minutes, and after staying in the precipitation area for 18 minutes, a primary treatment liquid is obtained. Specifically, the pH value of the primary treatment liquid is 9, the suspended matter concentration is 51 mg / L, the total zinc concentration is 38 mg / L, the total iron concentration is 64 mg / L, and the anionic surfactant concentration is 5 mg / L.

[0069] Specifically, in this example, the modified heavy metal precipitant is prepared by the following steps: preparing a calcium chloride solution with a mass fraction of 8% and a ferric chloride solution with a mass fraction of 18%, and mixing the calcium chloride solution with the ferric chloride solution in a ratio of 1:1 to obtain a mixed solution; adding 6 grams of activated carbon, 2 grams of diatomaceous earth and 0.8 grams of chitosan per liter of the mixed solution, stirring at a stirring speed of 68 rpm for 6 minutes, to obtain the modified heavy metal precipitant.

[0070] Next, the primary treatment liquid enters the modified ceramic microfiltration membrane device 22 provided with a modified ceramic microfiltration membrane through the secondary water inlet pump 21 for microfiltration treatment to obtain a secondary treatment liquid. Among them, the operating pressure of the modified ceramic microfiltration membrane device 22 is 0.12MPa, the filtration pore size is 0.24μm, and the cross flow velocity is 2.4m / s. The pH value of the secondary treatment liquid is 9, the suspended matter concentration is 3.6mg / L, the total zinc concentration is 0.8mg / L, the total iron concentration is 2.2mg / L, and the anionic surfactant concentration is 0.4mg / L.

[0071] More specifically, the modified ceramic microfiltration membrane is prepared by the following steps: selecting a tubular alumina ceramic membrane as a support and preparing a 6% ammonium nitrate solution by mass; soaking the support in the ammonium nitrate solution for 13 minutes, taking out the support, and washing it with clean water for 4 times; placing the washed support in a muffle furnace for roasting, heating it to 480°C at a heating rate of 5°C / min, keeping it at this temperature for 6 minutes, and then cooling it to room temperature; preparing a 47% aluminum isopropoxide solution by mass and placing it in a reactor. The support was taken out and immersed in an aluminum isopropoxide solution. The reactor was heated to 80°C and kept at this temperature for 75 minutes. 38 mL of 40% nitric acid solution was added to each liter of aluminum isopropoxide solution. The reactor was kept at 80°C for 48 minutes. The support was taken out and cooled to room temperature. The support was placed in a muffle furnace for calcination. The support was heated to 458°C at a heating rate of 4°C / min. After being kept at this temperature for 134 minutes, it was cooled to room temperature to obtain the modified ceramic microfiltration membrane. The porosity of the modified support increased to 46.5%, and the permeability was 812L / (m 2 ·h·bar).

[0072] Finally, the secondary treatment liquid enters the pH neutralization tank 32 through the tertiary water inlet pump 31. The automatic dosing device adds a 25% hydrochloric acid solution to the pH neutralization tank 32 according to the pH value of the secondary treatment liquid monitored by the online pH meter, and controls the pH value of the secondary treatment liquid to 6-8. After the secondary treatment liquid stays in the pH neutralization tank 32 for 3 minutes, the tertiary treatment liquid is obtained, and the tertiary treatment liquid is discharged through the drainage pump 33. The pH value of the tertiary treatment liquid is 7.2, the suspended matter concentration is 3.5 mg / L, the total zinc concentration is 0.7 mg / L, the total iron concentration is 2.2 mg / L, and the anionic surfactant concentration is 0.4 mg / L. It can be seen that the tertiary treatment liquid meets the discharge standards or reuse requirements and can be directly discharged or transported to the near-zero discharge system of wastewater.

[0073] Example 2: The water quality characteristics of the hot-dip galvanizing wastewater are: pH value 3, suspended solids concentration 3144 mg / L, total zinc concentration 687 mg / L, total iron concentration 1548 mg / L, anionic surfactant concentration 22 mg / L. The treatment steps for the hot-dip galvanizing wastewater are as follows:

[0074] First, the hot-dip galvanizing wastewater enters the pH regulating tank 12 through the primary water inlet pump 11. The automatic dosing device adds a 19% sodium hydroxide solution to the pH regulating tank 12 according to the pH value of the hot-dip galvanizing wastewater monitored by the online pH meter, and controls the pH value of the hot-dip galvanizing wastewater to 9-10.5. At the same time, the mechanical stirrer in the pH regulating tank 12 continuously stirs at a stirring speed of 68 rpm. After the hot-dip galvanizing wastewater stays in the pH regulating tank 12 for 5 minutes, pH-adjusted effluent is obtained.

[0075] Then, the pH-adjusted effluent is allowed to flow into the dosing area of ​​the dosing sedimentation tank 13 by gravity, and 821 mg / L of modified heavy metal precipitant is added to the dosing area. At the same time, the mechanical stirrer in the dosing area is continuously stirred at a stirring speed of 77 rpm. The pH-adjusted effluent enters the precipitation area after staying in the dosing area for 6 minutes, and after staying in the precipitation area for 19 minutes, a primary treatment liquid is obtained. Specifically, the pH value of the primary treatment liquid is 10, the suspended matter concentration is 62 mg / L, the total zinc concentration is 49 mg / L, the total iron concentration is 81 mg / L, and the anionic surfactant concentration is 6 mg / L.

[0076] Specifically, in this example, the modified heavy metal precipitant is prepared by the following steps: preparing a calcium chloride solution with a mass fraction of 11% and a ferric chloride solution with a mass fraction of 24%, and mixing the calcium chloride solution with the ferric chloride solution in a ratio of 1:1 to obtain a mixed solution; adding 8 grams of activated carbon, 3 grams of diatomaceous earth and 1.8 grams of chitosan per liter of the mixed solution, stirring at a stirring speed of 71 rpm for 7 minutes, to obtain the modified heavy metal precipitant.

[0077] Next, the primary treatment liquid enters the modified ceramic microfiltration membrane device 22 provided with a modified ceramic microfiltration membrane through the secondary water inlet pump 21 for microfiltration treatment to obtain a secondary treatment liquid. Among them, the operating pressure of the modified ceramic microfiltration membrane device 22 is 0.12MPa, the filtration pore size is 0.24μm, and the cross flow velocity is 2.4m / s. The pH value of the secondary treatment liquid is 10, the suspended matter concentration is 5mg / L, the total zinc concentration is 0.9mg / L, the total iron concentration is 3mg / L, and the anionic surfactant concentration is 0.6mg / L.

[0078] More specifically, the modified ceramic microfiltration membrane is prepared by the following steps: selecting a tubular alumina ceramic membrane as a support and preparing a 7% ammonium nitrate solution by mass; soaking the support in the ammonium nitrate solution for 15 minutes, taking out the support, and washing it with clean water for 5 times; placing the washed support in a muffle furnace for roasting, heating it to 510°C at a heating rate of 6°C / min, keeping it at this temperature for 8 minutes, and cooling it to room temperature; preparing a 55% aluminum isopropoxide solution and placing it in a reactor. The support was taken out and immersed in an aluminum isopropoxide solution. The reactor was heated to 81°C and kept at this temperature for 82 minutes. 50 mL of 41% nitric acid solution was added to each liter of aluminum isopropoxide solution. The reactor was kept at 81°C for 52 minutes. The support was taken out and cooled to room temperature. The support was placed in a muffle furnace for calcination. The support was heated to 463°C at a heating rate of 5°C / min. After being kept at this temperature for 138 minutes, it was cooled to room temperature to obtain the modified ceramic microfiltration membrane. The porosity of the modified support increased to 47.6%, and the permeability was 847L / (m 2 ·h·bar).

[0079] Finally, the secondary treatment liquid enters the pH neutralization tank 32 through the tertiary water inlet pump 31. The automatic dosing device adds a hydrochloric acid solution with a mass fraction of 26% to the pH neutralization tank 32 according to the pH value of the secondary treatment liquid monitored by the online pH meter, and controls the pH value of the secondary treatment liquid to 6-8. After the secondary treatment liquid stays in the pH neutralization tank 32 for 4 minutes, the tertiary treatment liquid is obtained, and the tertiary treatment liquid is discharged through the drainage pump 33. The pH value of the tertiary treatment liquid is 7.5, the suspended matter concentration is 4.9 mg / L, the total zinc concentration is 0.9 mg / L, the total iron concentration is 3 mg / L, and the anionic surfactant concentration is 0.6 mg / L. It can be seen that the tertiary treatment liquid meets the discharge standards or reuse requirements and can be directly discharged or transported to the near-zero discharge system of wastewater.

[0080] Embodiment 2

[0081] This embodiment provides a system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater. Figure 3 , Figure 3 The structural block diagram of the system for removing zinc, iron and anionic surfactant from hot-dip galvanizing wastewater provided in this embodiment. Figure 3It can be seen that the system includes a primary treatment module 1, a secondary treatment module 2 and a tertiary treatment module 3 which are arranged in sequence; the primary treatment module 1 is configured to perform pH adjustment treatment and coagulation and sedimentation treatment on the hot-dip galvanizing wastewater in sequence to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and sedimentation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater; the secondary treatment module 2 is configured to transport the primary treatment liquid to a modified ceramic microfiltration membrane device 22 for microfiltration treatment to obtain a secondary treatment liquid; wherein, a modified ceramic microfiltration membrane is arranged in the modified ceramic microfiltration membrane device 22; the tertiary treatment module 3 is configured to perform pH neutralization treatment on the secondary treatment liquid to obtain a tertiary treatment liquid.

[0082] Since the system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided in the present embodiment belongs to the same inventive concept as the method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater described in any of the above-mentioned embodiments, the system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided in the present embodiment has at least all the advantages of the method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided in the above-mentioned embodiments. For the advantages of the system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided in the present embodiment, please refer to the relevant description of the beneficial effects of the method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided in the above-mentioned embodiments, which will not be repeated here.

[0083] In summary, the method and system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention have the following advantages: the method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention comprises: sequentially performing pH adjustment treatment and coagulation and sedimentation treatment on the hot-dip galvanizing wastewater to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and sedimentation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater; the primary treatment liquid is transported to a modified ceramic microfiltration membrane device for microfiltration treatment to obtain a secondary treatment liquid; wherein a modified ceramic microfiltration membrane is arranged in the modified ceramic microfiltration membrane device; the secondary treatment liquid is subjected to pH neutralization treatment to obtain a tertiary treatment liquid. Thus, the method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention, by pH adjustment treatment of hot-dip galvanizing wastewater, lays the foundation for creating conditions conducive to subsequent coagulation and sedimentation treatment; by adding modified heavy metal precipitant to hot-dip galvanizing wastewater for coagulation and sedimentation treatment, suspended matter, zinc ions, iron ions, anionic surfactants and other substances in hot-dip galvanizing wastewater can be initially and effectively removed to obtain a primary treatment liquid. Then, by transporting the primary treatment liquid to a modified ceramic microfiltration membrane device provided with a modified ceramic microfiltration membrane for microfiltration treatment, suspended matter, zinc ions, iron ions, anionic surfactants and other substances in hot-dip galvanizing wastewater can be further efficiently removed to obtain a secondary treatment liquid. Finally, by pH neutralization treatment of the secondary treatment liquid, the pH value of the obtained tertiary treatment liquid can be within an appropriate range, so that it can meet the emission standards or reuse requirements. The method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention can simultaneously remove zinc ions, iron ions and anionic surfactants in hot-dip galvanizing wastewater, thereby improving the treatment efficiency of hot-dip galvanizing wastewater and reducing environmental pollution.

[0084] Further, the hot-dip galvanizing wastewater is subjected to pH adjustment treatment and coagulation and sedimentation treatment in sequence to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and sedimentation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater, including: transporting the hot-dip galvanizing wastewater to a pH adjustment tank, and adjusting the pH value of the hot-dip galvanizing wastewater to 9-10.5 to obtain pH-adjusted effluent; transporting the pH-adjusted effluent to a dosing sedimentation tank, and adding the modified heavy metal precipitant to the dosing sedimentation tank at a dosage of 687mg / L-932mg / L, so that the pH-adjusted effluent reacts with the modified heavy metal precipitant to obtain the primary treatment liquid. Therefore, the method for removing zinc, iron and anionic surfactants in hot-dip galvanizing wastewater provided by the present invention can help improve the efficiency of subsequent coagulation and sedimentation treatment by adjusting the pH value of the hot-dip galvanizing wastewater to 9-10.5. By adding modified heavy metal precipitants at a dosage of 687 mg / L to 932 mg / L into the dosing sedimentation tank, the modified heavy metal precipitants can more effectively combine with heavy metal ions such as zinc ions and iron ions in the pH-adjusted effluent to generate precipitates that are more easily settled, thereby enhancing the removal effect of suspended solids, zinc ions and iron ions.

[0085] Since the system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention belongs to the same inventive concept as the method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater described in any of the above items, the system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention at least has all the advantages of the method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention. For the advantages of the system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention, please refer to the relevant description of the beneficial effects of the system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater provided by the present invention, which will not be repeated here.

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater, characterized in that: The method comprises: The hot-dip galvanizing wastewater is subjected to pH adjustment treatment and coagulation and sedimentation treatment in sequence to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and sedimentation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater; The primary treatment liquid is transported to a modified ceramic microfiltration membrane device for microfiltration treatment to obtain a secondary treatment liquid; wherein the modified ceramic microfiltration membrane device is provided with a modified ceramic microfiltration membrane; The secondary treatment liquid is subjected to pH neutralization treatment to obtain a tertiary treatment liquid.

2. The method for removing zinc, iron and anionic surfactant from hot-dip galvanizing wastewater according to claim 1, characterized in that: The modified heavy metal precipitant is prepared by the following steps: SA1: preparing a calcium chloride solution with a mass fraction of 7% to 13% and a ferric chloride solution with a mass fraction of 16% to 26%, and mixing the calcium chloride solution with the ferric chloride solution in a ratio of 1:1 to obtain a mixed solution; SA2: Add 4 to 9 grams of activated carbon, 1 to 4 grams of diatomaceous earth and 0.4 to 2.5 grams of chitosan per liter of the mixed solution, stir at a stirring speed of 65 to 75 rpm for 5 to 8 minutes to obtain the modified heavy metal precipitant.

3. The method for removing zinc, iron and anionic surfactant from hot-dip galvanizing wastewater according to claim 1, characterized in that: The water quality of the hot-dip galvanizing wastewater before treatment is: total zinc is 556mg / L-760mg / L, total iron is 672mg / L-2312mg / L, anionic surfactant is 17mg / L-24mg / L, and pH is 2-4.

4. The method for removing zinc, iron and anionic surfactant from hot-dip galvanizing wastewater according to claim 1, characterized in that: The hot-dip galvanizing wastewater is subjected to pH adjustment treatment and coagulation and sedimentation treatment in sequence to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and sedimentation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater, comprising: The hot-dip galvanizing wastewater is transported to a pH adjustment tank, and the pH value of the hot-dip galvanizing wastewater is adjusted to 9 to 10.5 to obtain pH-adjusted effluent; The pH-adjusted effluent is transported to a dosing sedimentation tank, and the modified heavy metal precipitant is added to the dosing sedimentation tank at a dosage of 687 mg / L to 932 mg / L, so that the pH-adjusted effluent and the modified heavy metal precipitant undergo a coagulation and precipitation reaction to obtain the primary treatment liquid.

5. The method for removing zinc, iron and anionic surfactant from hot-dip galvanizing wastewater according to claim 4, characterized in that: The dosing sedimentation tank includes a dosing area and a sedimentation area. The modified heavy metal precipitant is added to the dosing area. The residence time of the pH-adjusted effluent in the dosing area is 4 minutes to 6 minutes, and the residence time of the pH-adjusted effluent in the sedimentation area is 17 minutes to 19 minutes.

6. The method for removing zinc, iron and anionic surfactant from hot-dip galvanizing wastewater according to claim 4, characterized in that: An online pH meter and an automatic dosing device are connected to the pH adjusting tank; the automatic dosing device is configured to add sodium hydroxide solution to the pH adjusting tank according to the pH value of the hot-dip galvanizing wastewater monitored by the online pH meter, so that the pH value of the hot-dip galvanizing wastewater is controlled at 9 to 10.

5.

7. The method for removing zinc, iron and anionic surfactant from hot-dip galvanizing wastewater according to claim 1, characterized in that: The modified ceramic microfiltration membrane is prepared by the following steps: SB1: Select an aluminum oxide ceramic membrane as a support and prepare an ammonium nitrate solution with a mass fraction of 6% to 7%; SB2: After soaking the support in the ammonium nitrate solution for 12 to 17 minutes, taking out the support and washing it 3 to 5 times; SB3: placing the cleaned support into a heating device, heating to 450°C to 530°C at a heating rate of 5°C / min to 7°C / min, maintaining the temperature for 5 to 9 minutes, and then cooling to room temperature; SB4: Prepare an aluminum isopropoxide solution with a mass fraction of 45% to 57% and place it in a reaction container, take out the support and immerse it in the aluminum isopropoxide solution, heat the reaction container to 79° C. to 83° C., keep it at this temperature for 68 minutes to 85 minutes, add 34 mL to 52 mL of a nitric acid solution with a mass fraction of 34% to 45% per liter of the aluminum isopropoxide solution, keep the reaction container at 79° C. to 83° C. for 45 minutes to 55 minutes, take out the support, and cool it to room temperature; SB5: Place the support body in the heating device, heat to 455°C to 467°C at a heating rate of 3°C / min to 5°C / min, maintain at this temperature for 123 minutes to 145 minutes, and then cool to room temperature to obtain the modified ceramic microfiltration membrane.

8. The method for removing zinc, iron and anionic surfactant from hot-dip galvanizing wastewater according to claim 7, characterized in that: The alumina ceramic membrane is tubular, the heating device comprises a muffle furnace, and the reaction container comprises a reaction kettle.

9. The method for removing zinc, iron and anionic surfactant from hot-dip galvanizing wastewater according to claim 1, characterized in that: The water quality of the tertiary treatment liquid is: total zinc is 0.5mg / L-1.1mg / L, total iron is 2mg / L-3mg / L, anionic surfactant is 0.3mg / L-0.7mg / L, and pH is 6-8.

10. A system for removing zinc, iron and anionic surfactants from hot-dip galvanizing wastewater, characterized in that: The system comprises a primary processing module, a secondary processing module and a tertiary processing module arranged in sequence; The primary treatment module is configured to sequentially perform pH adjustment treatment and coagulation and sedimentation treatment on the hot-dip galvanizing wastewater to obtain a primary treatment liquid; wherein, when the hot-dip galvanizing wastewater is subjected to the coagulation and sedimentation treatment, a modified heavy metal precipitant is added to the hot-dip galvanizing wastewater; The secondary treatment module is configured to transport the primary treatment liquid to the modified ceramic microfiltration membrane device for microfiltration treatment to obtain a secondary treatment liquid; wherein the modified ceramic microfiltration membrane device is provided with a modified ceramic microfiltration membrane; The tertiary treatment module is configured to perform pH neutralization treatment on the secondary treatment liquid to obtain a tertiary treatment liquid.

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