Prebaked anode roasting process wastewater treatment method

Abstract

The invention discloses a prebaked anode roasting process wastewater treatment method, and relates to the technical field of electrolytic aluminum. The method comprises the following steps: firstly, adding PAC into mud-containing wastewater, and destabilizing particles under the coagulation action of the PAC; pAM is added, particles are aggregated into a larger flocculating constituent through the flocculation effect of PAM, and the larger flocculating constituent is filtered to obtain primary wastewater and primary sludge. Oil and water can be separated by adding the decoloring and demulsifying powder into the primary wastewater, then the separated oily matter is flocculated and precipitated by adding the PAM, and finally secondary wastewater and secondary sludge are obtained by filtering. Wherein the primary sludge and the secondary sludge are treated according to a hazardous waste treatment procedure, and the secondary wastewater is treated according to a conventional sewage treatment procedure. The method can effectively reduce the treatment amount and the transfer amount of the hazardous waste and reduce the treatment cost.

Description

Technical Field

[0001] The invention relates to the technical field of electrolytic aluminum, in particular to a method for treating wastewater from a prebaked anode baking process. Background Art

[0002] In the baking process of prebaked anode production, in order to treat the waste gas and particulate matter generated during the baking process, environmental protection equipment such as spray towers, electric tar collectors, desulfurization towers, and wet electrostatic precipitators are needed to treat the flue gas. Spray towers, electric tar collectors, and wet electrostatic precipitators will produce acidic wastewater containing sludge during operation. The sludge is a hazardous waste and needs to be disposed of in accordance with relevant regulations. The traditional treatment method is to entrust the acidic wastewater containing sludge to a qualified third party for treatment, which has high treatment costs. Summary of the invention

[0003] In response to the above problems, the present application provides a method for treating wastewater from the pre-baked anode baking process, which can separate the sludge in the mud-containing wastewater and treat it as hazardous waste, while the sewage can be treated by conventional sewage treatment methods. This can reduce the amount of hazardous waste to be treated and transported, and reduce treatment costs.

[0004] The technical solution adopted by the present invention to solve the technical problem is:

[0005] A method for treating wastewater from a prebaked anode baking process comprises the following steps:

[0006] S1. Adding polyaluminium chloride into the muddy wastewater;

[0007] S2. Add alkaline substances to adjust the pH value of the muddy wastewater to neutral or weak alkaline;

[0008] S3, adding polyacrylamide;

[0009] S4, filtering to obtain primary sludge and primary wastewater, wherein the primary sludge is treated according to the hazardous waste treatment procedure;

[0010] S5, adding decolorizing and demulsifying powder to the primary wastewater obtained in step S4;

[0011] S6. Add alkaline substances to adjust the pH value of the primary wastewater to neutral or weak alkaline;

[0012] S7, adding polyacrylamide;

[0013] S8. Filter to obtain secondary sludge and secondary wastewater, wherein the secondary sludge is treated according to the hazardous waste treatment procedure, and the secondary wastewater is treated according to the conventional sewage treatment procedure.

[0014] Furthermore, in step S1, stirring or aeration treatment is performed after adding polyaluminium chloride.

[0015] Furthermore, in steps S3 and S7, stirring or aeration treatment is performed after adding polyacrylamide.

[0016] Furthermore, in step S1, the mass of the added polyaluminium chloride is 2‰ of the mass of the muddy wastewater to be treated.

[0017] Furthermore, the polyaluminium chloride is added in the form of a polyaluminium chloride aqueous solution.

[0018] Furthermore, in step S3, the mass of the added polyacrylamide is 1‰ of the mass of the muddy wastewater to be treated.

[0019] Furthermore, in step S7, the mass of the added polyacrylamide is 1‰ of the mass of the primary wastewater obtained in step S4.

[0020] Furthermore, the polyacrylamide is added in the form of a polyacrylamide aqueous solution.

[0021] Furthermore, in step S5, the mass of the decolorizing and demulsifying powder added is 1.6% of the mass of the primary wastewater obtained in step S4.

[0022] Furthermore, in steps S2 and S6, the alkaline substance is NaOH.

[0023] The beneficial effects of the present invention are:

[0024] A method for treating wastewater in a pre-baked anode baking process provided in an embodiment of the present application can achieve the separation of muddy and water from muddy wastewater generated in the baking process. The separated sludge is treated as hazardous waste, and the separated water can meet the treatment requirements of conventional sewage after demulsification and decolorization. It can be treated according to the conventional sewage treatment process, and the water after conventional treatment can be reused as reclaimed water. By using the method provided in the example of the present application, the amount of hazardous waste transportation and treatment can be reduced by more than 30%, and no secondary pollution and other hazardous wastes are generated during the treatment process. In addition, the separated wastewater can be reused as reclaimed water after conventional treatment, which can recycle more water resources and reduce the consumption of natural water resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A process flow chart of a method for treating wastewater from a pre-baked anode baking process provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described in detail below in conjunction with the drawings in the embodiments of the present application, and the described embodiments are only part of the embodiments of the present application, not all of the embodiments. All other embodiments obtained by those skilled in the art without creative work on the basis of the embodiments of the present application shall belong to the protection scope of the present application.

[0027] like Figure 1 As shown, a method for treating wastewater from a prebaked anode baking process comprises the following steps:

[0028] S1. Add PAC (polyaluminium chloride) to the wastewater containing mud and stir or aerate it for 3 to 5 minutes. Stirring or aerating can make the sludge in the wastewater containing mud in a suspended state and fully contact with PAC.

[0029] As a specific implementation, in step S1 of this embodiment, the PAC is added in the form of a PAC aqueous solution, and the mass of the PAC added is 2‰ of the mass of the muddy wastewater. Here, when calculating the mass of the added PAC, the mass of the water used to dissolve the PAC is ignored. For example, if M kilograms of muddy wastewater is treated, the mass of the added PAC is N=M*2‰, and the M kilograms of muddy wastewater do not include the mass of the water used to dissolve the PAC.

[0030] S2. Adding alkaline substances to the muddy wastewater obtained in step S1, so as to adjust the pH value of the muddy wastewater to above 8.

[0031] As a specific implementation, in step S2 of this embodiment, the alkaline substance is NaOH.

[0032] S3, PAM (polyacrylamide) is added to the muddy wastewater obtained in step S2, and stirred or aerated for 3 to 5 minutes. The solid matter therein can be flocculated and precipitated by stirring or aerating.

[0033] As a specific implementation, in step S3 of this embodiment, the PAM is added in the form of a PAM aqueous solution, and the mass of the PAM added is 1‰ of the mass of the muddy wastewater. Here, when calculating the mass of the added PAM, the mass of the water used to dissolve the PAM is ignored. For example, if M kilograms of muddy wastewater are treated, the mass of the added PAM is P=M*1‰, and the M kilograms of muddy wastewater do not include the mass of the water used to dissolve the PAM.

[0034] S4. Filter the muddy wastewater obtained in step S3 to obtain primary sludge and primary wastewater, wherein the primary sludge is treated according to the hazardous waste treatment procedure, and the primary wastewater enters the next step for subsequent treatment.

[0035] As a specific implementation, in step S4 of this embodiment, filter cloth is used to filter the muddy wastewater, and the filter diameter of the filter cloth is 100 μm.

[0036] S5, adding decolorizing and demulsifying powder to the primary wastewater obtained in step S4, and stirring or aerating for 5 to 10 minutes. Stirring or forcibly introducing air for aeration can suspend the substances in the primary wastewater and fully mix with the decolorizing and demulsifying powder, thereby accelerating the reaction.

[0037] As a specific implementation, the mass of the decolorizing and demulsifying powder added in this embodiment is 1.6% of the mass of the primary wastewater. For example, if M' kilograms of muddy wastewater is treated, the mass of the decolorizing and demulsifying powder added is Q = M'*1.6%.

[0038] S6. Adding alkaline substances to the primary wastewater obtained in step S5 to adjust the pH value of the primary wastewater to above 8.

[0039] As a specific implementation, in step S6 of this embodiment, the alkaline substance is NaOH.

[0040] S7. Add PAM (polyacrylamide) to the primary wastewater obtained in step S6, and stir or aerate for 3 to 5 minutes to cause the solid matter therein to flocculate and precipitate.

[0041] As a specific implementation, in step S7 of this embodiment, the PAM is added in the form of a PAM aqueous solution, and the mass of the PAM added is 1‰ of the mass of the primary wastewater. Here, when calculating the mass of the added PAM, the mass of the water used to dissolve the PAM is ignored. For example, if M' kilograms of primary wastewater are treated, the mass of the added PAM is R = M'*1‰, and the M' kilograms of primary wastewater do not include the mass of the water used to dissolve the PAM.

[0042] S8. Filter the primary wastewater obtained in step S7 to obtain secondary sludge and secondary wastewater, wherein the secondary sludge is treated according to the hazardous waste treatment procedure, and the secondary wastewater is treated according to the conventional sewage treatment procedure.

[0043] As a specific implementation, in step S8 of this embodiment, filter cloth is used to filter the primary wastewater, and the filter diameter of the filter cloth is 100 μm.

[0044] PAC is an inorganic polymer coagulant that can quickly precipitate colloids and fine suspended matter in sewage through the effects of double-layer compression, electrical neutralization, adsorption bridging and belt-net capture, making it easier to separate.

[0045] PAM is a high molecular weight organic flocculant that can aggregate fine particles into larger clusters through electrical neutralization and bridging flocculation mechanisms, promoting rapid sedimentation and filtration.

[0046] The muddy wastewater to be treated in this application contains solid particles, oily matter, floccules, etc. In this application, PAC is first added to the muddy wastewater to destabilize the particles through its coagulation effect; then PAM is added to aggregate the particles into larger flocs through its flocculation effect, so as to effectively remove them in the subsequent filtration treatment. The PAC and PAM can play a synergistic effect, thereby improving the mud-water separation effect of the muddy wastewater.

[0047] Since PAM usually has better flocculation effect in a neutral or weakly alkaline environment, the muddy wastewater and primary wastewater are adjusted to neutral or weakly alkaline by adding NaOH or other alkaline substances before adding PAM to improve the flocculation and sedimentation effects.

[0048] The effect of adding decolorizing and demulsifying powder in step S5 is to increase the viscosity of the emulsion, destroy its stability, and separate the oil and water. Specifically, the high molecular weight components in the decolorizing and demulsifying powder can be adsorbed on the oil-water interface, changing the interfacial properties, thereby separating the oil and water. Then, through adsorption and chemical reaction, the colored substances in the sewage are removed, thereby achieving the decolorization effect. Adding PAM again after adding the decolorizing and demulsifying powder can adsorb and flocculate the oil separated in step S5, which can improve the quality of the secondary wastewater finally obtained, so that the secondary wastewater can meet the treatment standards of conventional sewage.

[0049] Other embodiments obtained by those skilled in the art by combining, splitting, reorganizing, etc. the embodiments of the present application on the basis of the embodiments provided in the present application do not exceed the protection scope of the present application.

[0050] The above specific implementation methods have detailed the purpose, technical solutions and beneficial effects of the embodiments of the present application. The above are only specific implementation methods of the embodiments of the present application and are not used to limit the protection scope of the embodiments of the present application. That is, any modifications, equivalent substitutions, improvements, etc. made on the basis of the embodiments of the present application should be included in the protection scope of the embodiments of the present application.

Claims

1. A method for treating wastewater from a prebaked anode baking process, characterized in that: The following steps are included: S1. Adding polyaluminium chloride into the muddy wastewater; S2. Add alkaline substances to adjust the pH value of the muddy wastewater to neutral or weak alkaline; S3, adding polyacrylamide; S4, filtering to obtain primary sludge and primary wastewater, wherein the primary sludge is treated according to the hazardous waste treatment procedure; S5, adding decolorizing and demulsifying powder to the primary wastewater obtained in step S4; S6. Add alkaline substances to adjust the pH value of the primary wastewater to neutral or weak alkaline; S7, adding polyacrylamide; S8. Filter to obtain secondary sludge and secondary wastewater, wherein the secondary sludge is treated according to the hazardous waste treatment procedure, and the secondary wastewater is treated according to the conventional sewage treatment procedure.

2. The method for treating wastewater from a prebaked anode baking process according to claim 1, characterized in that: In step S1, polyaluminium chloride is added and then stirred or aerated.

3. The method for treating wastewater from a prebaked anode baking process according to claim 1, characterized in that: In steps S3 and S7, stirring or aeration treatment is performed after adding polyacrylamide.

4. The method for treating wastewater from a prebaked anode baking process according to claim 1, characterized in that: In step S1, the mass of the added polyaluminium chloride is 2‰ of the mass of the muddy wastewater to be treated.

5. The method for treating wastewater from a prebaked anode baking process according to claim 1, characterized in that: The polyaluminium chloride is added in the form of a polyaluminium chloride aqueous solution.

6. The method for treating wastewater from a prebaked anode baking process according to claim 1, characterized in that: In step S3, the mass of the added polyacrylamide is 1‰ of the mass of the muddy wastewater to be treated.

7. The method for treating wastewater from a prebaked anode baking process according to claim 1, characterized in that: In step S7, the mass of the added polyacrylamide is 1‰ of the mass of the primary wastewater obtained in step S4.

8. The method for treating wastewater from a prebaked anode baking process according to claim 1, characterized in that: The polyacrylamide is added in the form of polyacrylamide aqueous solution.

9. The method for treating wastewater from a prebaked anode baking process according to claim 1, characterized in that: In step S5, the mass of the decolorizing and demulsifying powder added is 1.6% of the mass of the primary wastewater obtained in step S4.

10. The method for treating wastewater from a prebaked anode baking process according to claim 1, characterized in that: In steps S2 and S6, the alkaline substance is NaOH.

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