A method for treating cobalt smelting wastewater

Abstract

The present invention relates to the field of wastewater treatment technology and provides a method for treating cobalt smelting wastewater. The method first pretreats the cobalt smelting wastewater using a coagulant and aeration. A treatment agent is then added under oxygen exposure to react and degrade organic matter in the wastewater. Suspended matter is then removed through flocculation. Finally, sodium hypochlorite is added and filtered to obtain wastewater with COD and color that meet standards. The method provided by the present invention is simple to operate, low in cost, and free of secondary pollution. It is economical and environmentally compatible, and can effectively remove COD and color from cobalt smelting wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a method for treating cobalt smelting wastewater. Background Art

[0002] With the continuous development and advancement of science and technology, the production and consumption of cobalt have increased rapidly, finding widespread application in the manufacture of alloys, magnetic materials, lithium-ion batteries, and catalysts. The production of cobalt materials generates significant amounts of cobalt smelting wastewater. Due to the extensive use of chemicals in the production process, cobalt smelting wastewater exhibits the "three highs" characteristics of high ammonia nitrogen, high COD, and high color. This represents a typical example of highly toxic and difficult-to-degrade organic industrial wastewater. The organic pollutants and high levels of inorganic salts in this wastewater have a strong inhibitory effect on microorganisms. If not effectively treated, it can pose significant risks to the ecological environment and human health.

[0003] Existing wastewater treatment methods typically include biological treatment, membrane separation, adsorption, and chemical oxidation. Biological treatment is generally not suitable for treating nonferrous metallurgical wastewater because microorganisms are intolerant to high salt concentrations, require large space, and have high construction costs. Membrane separation relies heavily on the selection of membrane materials, which are expensive, and presents a high risk of membrane fouling and clogging when treating organic wastewater. Adsorption is effective in removing dissolved organic matter, but to save costs and avoid secondary contamination from solid waste, the regeneration of the adsorption material is necessary, resulting in a complex process and significant equipment investment. Chemical oxidation consumes large amounts of reagents and has high operating costs.

[0004] Therefore, the current treatment methods are costly and have poor economic efficiency. There is an urgent need to provide a treatment method for cobalt smelting wastewater that is economical, simple to operate, and has good treatment effects. Summary of the Invention

[0005] In view of this, the present invention provides a method for treating cobalt smelting wastewater. The treatment method provided by the present invention is economical, simple to operate, and has good environmental compatibility, and can achieve efficient removal of COD and chroma in cobalt smelting wastewater.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A method for treating cobalt smelting wastewater comprises the following steps:

[0008] (1) mixing the cobalt smelting wastewater and the coagulant, and then aerating and settling the mixture in sequence to obtain a first supernatant;

[0009] (2) mixing the first supernatant and the treatment agent, and reacting them under aeration conditions to obtain reacted sewage;

[0010] (3) mixing the wastewater after the reaction in step (2) with a biological flocculant, performing flocculation treatment under aeration conditions, and then performing a second static sedimentation to obtain a second supernatant;

[0011] (4) The second supernatant and sodium hypochlorite are mixed and filtered.

[0012] Preferably, the coagulant comprises the following components in parts by mass: 5-15 parts of ferric sulfate, 10-30 parts of potassium ferrate, 10-18 parts of polyferric sulfate, 20-60 parts of diatomaceous earth, 11-16 parts of sodium citrate, and 8-19 parts of polyacrylamide.

[0013] Preferably, the aeration time in step (1) is 2 to 6 hours, and the first static sedimentation time is 2 to 8 hours;

[0014] In the step (1), the pH value of the cobalt smelting wastewater is 7-9, and the oxygen flow rate of aeration is 0.1-0.5 L / min.

[0015] Preferably, the treatment agent includes at least one of clay, zeolite, nano zero-valent iron and Fe3O4.

[0016] Preferably, the treatment agent is composed of clay, zeolite, nano-zero-valent iron and Fe3O4; the mass ratio of the clay, zeolite, nano-zero-valent iron and Fe3O4 is 1:0.6:(0.1-0.5):(0.05-0.2);

[0017] The preparation method of the treatment agent comprises: mixing nanometer zero-valent iron, Fe3O4, clay, zeolite and water and then heat-treating to obtain the treatment agent; the heat treatment temperature is 600-900°C and the time is 20-50 minutes.

[0018] Preferably, the amount of the treatment agent is 0.1-8 g / L; the reaction time in step (2) is 2-6 h; the oxygen flow rate of aeration in step (2) is 0.1-0.5 L / min; and the pH value of the first supernatant in step (2) is 7-8.

[0019] Preferably, the biological flocculant is activated sludge; the amount of the biological flocculant added is 50~300 mL / L; the flocculation treatment time is 8~12 h; the second static sedimentation time is 2~6 h; the oxygen flow rate of aeration in step (3) is 0.1~0.5 L / min.

[0020] Preferably, the aeration in steps (1), (2) and (3) is performed using a micro-nano bubble generator.

[0021] Preferably, the amount of sodium hypochlorite added is 5-30 mmol / L; and the filtration system used for filtration is composed of inorganic particles.

[0022] Preferably, the initial COD value of the cobalt smelting wastewater is 2000~3000 mg / L, and the chromaticity value is 100~200 times.

[0023] The present invention provides a method for treating cobalt smelting wastewater, comprising the following steps: (1) mixing the cobalt smelting wastewater with a coagulant, and then aerating and performing a first static sedimentation in sequence to obtain a first supernatant; (2) mixing the first supernatant with a treatment agent, and reacting under aeration conditions to obtain reacted sewage; (3) mixing the sewage after the reaction in step (2) with a biological flocculant, and performing a flocculation treatment under aeration conditions, and then performing a second static sedimentation to obtain a second supernatant; (4) mixing the second supernatant with sodium hypochlorite and filtering. The present invention first pre-treats the cobalt smelting wastewater by using a coagulant and aeration, then adding a treatment agent under oxygen exposure conditions to react to degrade organic matter in the wastewater, then removing suspended matter in the wastewater by flocculation treatment, and finally adding sodium hypochlorite, and filtering to obtain wastewater with COD and chroma meeting standards. The method provided by the present invention is simple to operate, low in cost, free of secondary pollution, and has good economy and environmental compatibility, and can achieve efficient removal of COD and chroma in cobalt smelting wastewater. Furthermore, the present invention adopts a micro-nano bubble generator for aeration, and the generated micro-nano bubbles can promote the sedimentation of organic matter after being wrapped by the bubbles and combined with the coagulant, which is beneficial to improving the removal effect of organic matter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic flow chart of the method for treating cobalt smelting wastewater provided by the present invention. DETAILED DESCRIPTION

[0025] The present invention provides a method for treating cobalt smelting wastewater, comprising the following steps:

[0026] (1) mixing the cobalt smelting wastewater and the coagulant, and then aerating and settling the mixture in sequence to obtain a first supernatant;

[0027] (2) mixing the first supernatant and the treatment agent, and reacting them under aeration conditions to obtain reacted sewage;

[0028] (3) mixing the wastewater after the reaction in step (2) with a biological flocculant, performing flocculation treatment under aeration conditions, and then performing a second static sedimentation to obtain a second supernatant;

[0029] (4) The second supernatant and sodium hypochlorite are mixed and filtered.

[0030] The present invention combines cobalt smelting wastewater with a coagulant, followed by aeration and a first static sedimentation step to produce a first supernatant. In the present invention, the initial COD value of the cobalt smelting wastewater is preferably 2000-3000 mg / L, and the chromaticity value is 100-200 times. The present invention has no particular requirements for the source of the cobalt smelting wastewater; any cobalt smelting wastewater commonly found in the art can be treated using the method of the present invention.

[0031] In the present invention, the coagulant preferably includes the following components in parts by mass: 5-15 parts of ferric sulfate, 10-30 parts of potassium ferrate, 10-18 parts of polyferric sulfate, 20-60 parts of diatomaceous earth, 11-16 parts of sodium citrate, and 8-19 parts of polyacrylamide; wherein the mass portion of the ferric sulfate is preferably 5 parts, 10 parts or 15 parts, the mass portion of potassium ferrate is preferably 15 parts, 20 parts or 30 parts, the mass portion of polyferric sulfate is preferably 10 parts, 12 parts or 15 parts, the mass portion of diatomaceous earth is preferably 20 parts or 30 parts, the mass portion of sodium citrate is preferably 12 parts, and the mass portion of polyacrylamide is preferably 10 parts or 15 parts.

[0032] In the present invention, the amount of the coagulant added is preferably 50 to 100 mg / L. In the present invention, the coagulant is preferably slowly added to the cobalt smelting wastewater, and the formation of precipitates in the wastewater is observed. When no more precipitates are formed, the addition of the coagulant is stopped, and aeration is then started.

[0033] In the present invention, the pH value of the cobalt smelting wastewater in step (1) is preferably 7 to 9. In a specific embodiment of the present invention, the initial pH value of the cobalt smelting wastewater is about 6.5. The present invention preferably uses an alkali to adjust the pH value of the cobalt smelting wastewater to 7 to 9, and the alkali is preferably sodium hydroxide. The aeration time in step (1) is preferably 2 to 6 hours, more preferably 3 to 5 hours; the oxygen flow rate of aeration is preferably 0.1 to 0.5 L / min. In the present invention, the aeration is preferably carried out using a micro-nano bubble generator, which will not be described in detail later; the first static sedimentation time is preferably 2 to 8 hours, more preferably 3 to 6 hours.

[0034] After obtaining the first supernatant, the present invention mixes the first supernatant with a treatment agent and reacts the mixture under aeration conditions to obtain reacted sewage. In the present invention, the first supernatant obtained by the first static precipitation is preferably introduced into a reaction tank for treatment, and the pH value of the first supernatant is preferably 7-8; the treatment agent preferably includes at least one of clay, zeolite, nano-zero-valent iron and Fe3O4; more preferably, the treatment agent is composed of clay, zeolite, nano-zero-valent iron and Fe3O4; the mass ratio of the clay, zeolite, nano-zero-valent iron and Fe3O4 is preferably 1:0.6:(0.1-0.5):(0.05-0.2), more preferably 1:0.6:0.25:0.1; the preparation method of the treatment agent preferably comprises: mixing nano-zero-valent iron, Fe3O4, clay, zeolite and water and then heat-treating to obtain the treatment agent; the heat treatment temperature is preferably 600-900°C, more preferably 700-800°C, and the heat treatment time is preferably 20-50 min, more preferably 30-40 min; the heat treatment is preferably carried out under nitrogen protection; the water is preferably deionized water. The present invention has no special requirements for the amount of water used, as long as it can soak the mixture of nano-zero-valent iron, Fe3O4, clay and zeolite; in the present invention, the mixture of clay, zeolite, nano-zero-valent iron and Fe3O4 will form a treatment agent with a porous structure after heat treatment. The present invention preferably crushes the treatment agent obtained after the heat treatment and then sieves it to form treatment agent particles for easy use.

[0035] In the present invention, the dosage of the treatment agent is preferably 0.1-8 g / L, more preferably 1-5 g / L; the reaction time in step (2) is preferably 2-6 h, more preferably 3-5 h; the oxygen flow rate of aeration in step (2) is preferably 0.1-0.5 L / min, more preferably 0.2-0.4 L / min.

[0036] After the reaction is completed, the present invention mixes the wastewater after the reaction in step (2) with a biological flocculant, performs a flocculation treatment under aeration conditions, and then performs a second static sedimentation to obtain a second supernatant. In the present invention, the wastewater after the reaction in step (2) is preferably introduced into a flocculation tank; the biological flocculant is preferably activated sludge; the amount of the biological flocculant added is preferably 50 to 300 mL / L, more preferably 100 to 200 mL / L; the flocculation treatment time is preferably 8 to 12 hours, more preferably 9 to 11 hours, and the flocculation treatment is preferably performed under stirring conditions.

[0037] After the flocculation treatment is completed, the treated wastewater is preferably introduced into a sedimentation tank for a second static sedimentation; the second static sedimentation time is preferably 2 to 6 hours, more preferably 3 to 5 hours; the oxygen flow rate of aeration in step (3) is preferably 0.1 to 0.5 L / min, more preferably 0.2 to 0.4 L / min. In a specific embodiment of the present invention, the precipitate obtained by the second static sedimentation is preferably cultured in a bioreactor to achieve regeneration of the bioflocculant; the present invention has no special requirements for the culture method, and methods well known to those skilled in the art can be used.

[0038] After obtaining the second supernatant, the present invention mixes the second supernatant with sodium hypochlorite and then filters. In the present invention, it is preferred to add sodium hypochlorite to the second supernatant, and then introduce the wastewater into a filter tank; the amount of sodium hypochlorite added is preferably 5 to 30 mmol / L, more preferably 10 to 20 mmol / L; the filtration system used for filtration is preferably composed of inorganic particles; the inorganic particles preferably include quartz sand and / or zeolite. In a specific embodiment of the present invention, it is preferred to add sulfuric acid to the filter tank, adjust the pH value of the wastewater to neutral, and then filter. The COD and color of the filtered wastewater meet the standards, and the qualified wastewater can be discharged into a sewage treatment plant for further treatment. The present invention can further decolorize and enhance the COD removal effect by adding sodium hypochlorite. In a specific embodiment of the present invention, because the water quality of cobalt smelting wastewater fluctuates, large fluctuations may cause the wastewater to exceed the standard, so sodium hypochlorite is added in the final treatment process; and part of the cobalt smelting wastewater comes from the extraction section and contains ammonia nitrogen. Although the front end includes an ammonia nitrogen treatment process, the production process may have unexpected situations, and ammonia nitrogen also needs to be monitored at the back end. If the ammonia nitrogen in the wastewater exceeds the standard, it can be treated by this process to meet the standard.

[0039] In the present invention, after filtration, qualified wastewater with COD and chroma meeting the standards is obtained; the COD value of the qualified wastewater is less than 100 mg / L and the chroma is less than 50 times, which meets the requirements of the first-level emission standard of the "Integrated Sewage Discharge Standard" (GB8978-1996).

[0040] Figure 1 The present invention provides a flow diagram of a method for treating cobalt smelting wastewater. The method comprises the following steps: first, sodium hydroxide is added to adjust the pH value of the cobalt smelting wastewater to 7-9; then, a coagulant is added and aeration (i.e., coagulation and flotation) is performed; the supernatant obtained after treatment is added with a treatment agent under oxygen exposure conditions for reaction; the wastewater after reaction is added with a biological flocculant for flocculation; the flocculated wastewater is allowed to settle in a sedimentation tank; the obtained precipitate is subjected to flocculant regeneration; the obtained supernatant enters a filtration tank, is added with sodium hypochlorite, and then filtered to obtain qualified wastewater.

[0041] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example 1

[0042] Taking the treatment of smelting wastewater from a cobalt smelting plant as an example, the COD content of the cobalt smelting wastewater before treatment was 2541 mg / L, the pH was 6.5, and the chromaticity was 210. When production fluctuated, its chemical composition also changed to a certain extent. The cobalt smelting wastewater treatment method of the present invention is used to treat the cobalt smelting wastewater. The treatment steps are shown in FIG. Figure 1 As shown, specifically including:

[0043] (1) Coagulation-flotation treatment: The wastewater generated during the cobalt-tungsten smelting process is collected in a wastewater pool, the pH is adjusted to 8 with alkali, a coagulant is added, aeration is carried out for 4 hours, and static sedimentation is carried out for 5 hours;

[0044] The coagulant components, by weight, are: 5 parts ferric sulfate, 15 parts potassium ferrate, 10 parts polyferric sulfate, 20 parts diatomaceous earth, 12 parts sodium citrate, and 10 parts polyacrylamide. The coagulant is slowly added to the wastewater until no more precipitation occurs.

[0045] Aeration was performed using a micro-nano bubble generator, and the oxygen flow rate was 0.2 L / min.

[0046] (2) The supernatant obtained after static sedimentation in step (1) is introduced into the reaction tank, and the treatment agent is added to the reaction tank, and aeration is carried out for 3 hours;

[0047] The treatment agent particles are composed of nano-zero-valent iron, Fe3O4, clay and zeolite. The preparation method of the treatment agent is: clay, zeolite, nano-zero-valent iron and Fe3O4 are mixed in a mass ratio of 1:0.6:0.25:0.1, deionized water is added to soak the mixture, and heat treatment is carried out at 600 ° C for 20 minutes under nitrogen atmosphere.

[0048] The amount of treatment agent added was 200 mg / L, aeration in the wastewater pool was carried out using a micro-nano bubble generator, and the oxygen flow rate of aeration was 0.2 L / min.

[0049] (3) Biological flocculation: the wastewater treated in step (2) is sent to the flocculation tank, biological flocculant is added to the flocculation tank, aeration and stirring reaction is carried out for 8 hours, and static sedimentation is carried out for 3 hours;

[0050] The bioflocculant was activated sludge, added at a rate of 100 mL / L; aeration was carried out using a micro-nano bubble generator, with an oxygen flow rate of 0.1 L / min.

[0051] (4) Filtration: The wastewater treated in step (3) is added with sodium hypochlorite and sent to the filtration system to adjust the pH to neutral. The precipitated water is directly discharged into the sewage outlet and prepared to be discharged into the sewage treatment plant.

[0052] Among them, the dosage of sodium hypochlorite is 10 mmol / L. Example 2

[0053] Taking the treatment of smelting wastewater from a cobalt smelting plant as an example, the COD content of the cobalt smelting wastewater before treatment was 2541 mg / L, the pH was 6.5, and the chromaticity was 210. When production fluctuated, its chemical composition also changed to a certain extent. The cobalt smelting wastewater was treated by the treatment method of the present invention. The treatment steps are shown in FIG. Figure 1 As shown, specifically including:

[0054] (1) Coagulation-flotation treatment: The wastewater generated during the cobalt smelting process was collected into a wastewater pool, the pH was adjusted to 8 with alkali, a coagulant was added, aeration was carried out for 5 h, and the wastewater was allowed to settle for 5 h;

[0055] The coagulant components, by weight, are: 10 parts ferric sulfate, 20 parts potassium ferrate, 10 parts polyferric sulfate, 30 parts diatomaceous earth, 12 parts sodium citrate, and 10 parts polyacrylamide. The coagulant is slowly added to the wastewater until no more precipitation occurs.

[0056] Aeration was performed using a micro-nano bubble generator, and the oxygen flow rate was 0.3 L / min.

[0057] (2) The supernatant obtained after the static sedimentation treatment in step (1) is introduced into the reaction tank, and the treatment agent is added to the reaction tank, and aeration is carried out for 4 hours;

[0058] The treatment agent was the same as that in Example 1, the amount of the treatment agent added was 300 mg / L, aeration was performed using a micro-nano bubble generator, and the oxygen flow rate of aeration was 0.2 L / min.

[0059] (3) Biological flocculation: the wastewater treated in step (2) is sent to the flocculation tank, biological flocculant is added to the flocculation tank, aeration and stirring reaction is carried out for 10 hours, and static sedimentation is carried out for 3 hours;

[0060] The bioflocculant was activated sludge, and the addition amount of the bioflocculant was 200 mL / L. Aeration was carried out using a micro-nano bubble generator, and the oxygen flow rate of aeration was 0.1 L / min.

[0061] (4) Filtration: The wastewater treated in step (3) is added with sodium hypochlorite and sent to the filtration system to adjust the pH to neutral. The precipitated water is directly discharged into the sewage outlet and prepared to be discharged into the sewage treatment plant.

[0062] Among them, the dosage of sodium hypochlorite is 20 mmol / L. Example 3

[0063] Taking the treatment of smelting wastewater from a cobalt smelting plant as an example, the COD content of the cobalt smelting wastewater before treatment was 2541 mg / L, the pH was 6.5, and the chromaticity was 210. When production fluctuated, its chemical composition also changed to a certain extent. The cobalt smelting wastewater treatment method of the present invention is used to treat the cobalt smelting wastewater. The treatment steps are shown in FIG. Figure 1 As shown, specifically including:

[0064] (1) Coagulation-flotation treatment: The wastewater generated during the cobalt smelting process was collected into a wastewater pool, the pH was adjusted to 8 with alkali, a coagulant was added, aeration was performed for 6 h, and the mixture was allowed to stand for 5 h;

[0065] The coagulant components, by mass, are: 15 parts ferric sulfate, 30 parts potassium ferrate, 10 parts polyferric sulfate, 30 parts diatomaceous earth, 12 parts sodium citrate, and 15 parts polyacrylamide. The coagulant is slowly added to the wastewater until no more precipitation occurs.

[0066] Aeration was performed using a micro-nano bubble generator, and the oxygen flow rate was 0.4 L / min.

[0067] (2) The supernatant obtained after the precipitation treatment in step (1) is introduced into the reaction tank, and the treatment agent is added to the reaction tank, and aeration is carried out for 5 hours;

[0068] The treatment agent was the same as that in Example 1, and the amount of the treatment agent added was 300 mg / L. A micro-nano bubble generator was used for aeration in the wastewater pool, and the oxygen flow rate of aeration was 0.2 L / min.

[0069] (3) Biological flocculation: The wastewater treated in step (2) is sent to the flocculation tank, and biological flocculant is added to the flocculation tank. The aeration and stirring reaction is carried out for 12 hours, and the wastewater is allowed to settle for 3 hours.

[0070] Among them, the biological flocculant is activated sludge, and the addition amount of the biological flocculant is 300 mL / L.

[0071] Aeration was performed using a micro-nano bubble generator, and the oxygen flow rate was 0.1 L / min.

[0072] (4) Filtration: The wastewater treated in step (3) is added with sodium hypochlorite and sent to the filtration system to adjust the pH to neutral. The precipitated water is directly discharged into the sewage outlet and prepared to be discharged into the sewage treatment plant.

[0073] Among them, the dosage of sodium hypochlorite is 30 mmol / L.

[0074] The COD value, pH value and chromaticity of the wastewater treated in Examples 1 to 3 are shown in Table 1.

[0075] Table 1 Water quality analysis before and after treatment

[0076] project <![CDATA[COD cr (mg / L)]]> pH Chroma (times) raw water 2541 6.5 210 Example 1 81 7.2 28 Example 2 65 7.5 18 Example 3 58 6.8 16

[0077] From the data in Table 1, it can be seen that the COD of the cobalt smelting wastewater treated in Examples 1 to 3 is less than 100 mg / L and the chromaticity is less than 50 times, which meets the requirements of the first-level discharge standard of the "Integrated Wastewater Discharge Standard" (GB8978-1996). cr The removal rate of chroma is high, the treatment effect is good, the process is simple, and there is no need to use expensive equipment and reagents, so the cost is low and the economy is good.

[0078] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for treating cobalt smelting wastewater, characterized in that: The following steps are involved: (1) mixing cobalt smelting wastewater and a coagulant, and then aerating and settling the mixture in sequence to obtain a first supernatant; (2) mixing the first supernatant and the treatment agent, and reacting them under aeration conditions to obtain treated sewage; (3) mixing the wastewater treated in step (2) with a biological flocculant, performing flocculation treatment under aeration conditions, and then performing a second static sedimentation to obtain a second supernatant; (4) mixing the second supernatant and sodium hypochlorite and filtering; The initial COD value of the cobalt smelting wastewater is 2000~3000mg / L, and the chromaticity value is 100~200 times; The coagulant comprises the following components: 5-15 parts of ferric sulfate, 10-30 parts of potassium ferrate, 10-18 parts of polymerized ferric sulfate, 20-60 parts of diatomaceous earth, 11-16 parts of sodium citrate, and 8-19 parts of polyacrylamide; The filtration system used in the filtration is composed of inorganic particles; The preparation method of the treatment agent includes: mixing nano-zero-valent iron, Fe3O4, clay, zeolite and water and then heat-treating to obtain the treatment agent; the heat treatment temperature is 600-900°C and the time is 20-50 minutes; the mass ratio of the clay, zeolite, nano-zero-valent iron and Fe3O4 is 1:0.6:(0.1-0.5):(0.05-0.2); The dosage of the treatment agent is 0.1-8 g / L; the reaction time in step (2) is 2-6 h; the oxygen flow rate of aeration in step (2) is 0.1-0.5 L / min; the pH value of the first supernatant in step (2) is 7-8; and the aeration in step (2) is performed using a micro-nano bubble generator.

2. The processing method according to claim 1, characterized in that The aeration time in step (1) is 2 to 6 hours, and the first static sedimentation time is 2 to 8 hours; In step (1), the pH value of the cobalt smelting wastewater is 7-9, and the oxygen flow rate of aeration is 0.1-0.5 L / min.

3. The processing method according to claim 1, characterized in that The biological flocculant is activated sludge; the amount of the biological flocculant added is 50~300mL / L; the flocculation treatment time is 8~12h; the second static sedimentation time is 2~6h; the oxygen flow rate of aeration in step (3) is 0.1~0.5L / min.

4. The processing method according to claim 1, characterized in that The aeration in step (1) and step (3) is carried out using a micro-nano bubble generator.

5. The processing method according to claim 1, characterized in that The amount of sodium hypochlorite added is 5-30 mmol / L.

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