A method and device for treating nickel-containing waste liquid

Abstract

The invention discloses a method and device for treating nickel-containing waste liquid, and belongs to the technical field of wastewater treatment. The method for treating nickel-containing waste liquid comprises: mixing nickel-containing waste liquid, iron plate and potassium persulfate to obtain a mixed liquid; adjusting the pH of the mixed liquid to 9.2-9.5, then adding a first flocculant for a first precipitation to obtain a first supernatant; adjusting the pH of the first supernatant to 9.5-9.8, then adding calcium chloride and polyaluminium chloride for mixed stirring reaction, and then continuing to add a second flocculant for a second precipitation to obtain a second supernatant. The nickel-containing wastewater treatment device comprises a reaction tank, a first reaction zone, a second reaction zone, a first precipitation zone, a third reaction zone, a fourth reaction zone, a fifth reaction zone and a second precipitation zone connected in sequence. The treatment method proposed by the invention can efficiently remove nickel and phosphorus through two precipitations, simplifying the process of chemical nickel plating wastewater treatment technology.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method and device for treating nickel-containing waste liquid. Background Art

[0002] Chemical nickel plating is a surface treatment process widely used in automobile manufacturing, medical equipment, aerospace, military manufacturing, electronic information and other fields. It is also an irreplaceable surface treatment technology, mainly including chemical nickel plating of aluminum alloy, chemical nickel plating of iron parts, chemical nickel plating of stainless steel, etc. The normal use frequency of chemical nickel plating bath is 40 to 60 times / batch, and the total amount of scrapped bath is large. The main components of the bath are HPNiE-380 content of 50-70ml / L, HPNiE-381 content of 120-160ml / L, metal nickel content of 5.4-6.4g / L, sodium hypophosphite content of 27-38g / L, pH value of 4.6-5.0, ammonium water, 25% sulfuric acid and complex. The current treatment method of waste bath is to transfer it to hazardous waste treatment manufacturers for hazardous waste treatment, and the treatment price is about 5,000 to 7,000 yuan / ton. The treatment price is high, which causes the product cost to remain high.

[0003] Chemical nickel plating wastewater is mainly the cleaning wastewater of the chemical nickel plating process. The pollutant composition in the cleaning water is consistent with the bath liquid due to the bath liquid, and the concentration is relatively lower than the bath liquid. The total nickel content is ≤1000mg / L, the total phosphorus content is ≤2000mg / L, and the pH value is about neutral. The existing treatment methods for this wastewater are Fenton method, electrocoagulation catalytic oxidation method, chemical precipitation method and biochemical method. The process is complicated, the water quality of the treated water is unstable, and the treatment cost is high.

[0004] In summary, the research and development of chemical nickel plating waste tank liquid treatment technology can make up for the technical gap; chemical nickel plating wastewater treatment technology needs to solve technical problems such as complex procedures, reducing treatment costs, ensuring good treatment effects, and stable water quality. Summary of the invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, provide a method and device for treating nickel-containing waste liquid, and solve the technical problem of complex technical procedures for chemical nickel plating wastewater treatment in the prior art.

[0006] In order to achieve the above technical purpose, the technical solution of the present invention provides a method for treating nickel-containing waste liquid, comprising the following steps:

[0007] S1, mixing nickel-containing waste liquid, iron plate and potassium persulfate, and reacting at a temperature of 80-95° C. and a pH value of 4.5-5.5 to obtain a mixed solution;

[0008] S2, cooling the mixed solution to below 40° C., adjusting the pH to 9.2 to 9.5, and then adding a first flocculant to perform a first precipitation to obtain a first supernatant;

[0009] S3, adjusting the pH of the first supernatant obtained in step S2 to 9.5-9.8, then adding calcium chloride and polyaluminium chloride to mix and stir for reaction, and then continuing to add the second flocculant to perform a second precipitation to obtain a second supernatant.

[0010] In any embodiment, in step S1, the amount of potassium persulfate added is 3%-5% of the mass of the nickel-containing waste liquid.

[0011] In any embodiment, in step S1, the reaction time is 30-40 min.

[0012] In any embodiment, in step S1, the iron plate is a cobalt-plated iron plate, a pick-plated iron plate or a passivated iron plate.

[0013] In any embodiment, in step S2, the first flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.1%-0.2%; the amount of the polyacrylamide added is 0.5%-0.8% of the volume of the mixed solution.

[0014] In any embodiment, in step S3, the second flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.1%-0.2%; the amount of the polyacrylamide added is 0.2%-0.4% of the volume of the first supernatant.

[0015] In any embodiment, in step S2, the first precipitation time is 2.5-4 hours.

[0016] In any embodiment, in step S3, the time of the second precipitation is 4-5 hours; and / or, in step S3, the addition amount of the aluminum chloride and the polyaluminum chloride is.

[0017] In addition, the present invention also provides a nickel-containing wastewater treatment device, comprising a reaction tank, a first reaction zone, a second reaction zone, a first precipitation zone, a third reaction zone, a fourth reaction zone, a fifth reaction zone and a second precipitation zone connected in sequence;

[0018] The reaction tank is used to mix the nickel-containing waste liquid, iron plate and potassium persulfate, and react at a temperature of 80 to 95° C. and a pH value of 4.5 to 5.5 to obtain a mixed solution;

[0019] The first reaction zone is used to cool the mixed solution to below 40° C., and then adjust the pH to 9.2-9.5;

[0020] The second reaction zone is used to add the first flocculant;

[0021] The first precipitation zone is used to perform a first precipitation to obtain a first supernatant;

[0022] The third reaction zone is used to adjust the pH of the first supernatant to 9.5-9.8;

[0023] The fourth reaction zone is used to add calcium chloride and polyaluminium chloride for mixed stirring reaction;

[0024] The fifth reaction zone is used to continue adding the second flocculant;

[0025] The second precipitation zone is used for performing a second precipitation.

[0026] Compared with the prior art, the beneficial effects of the present invention include: mixing nickel-containing waste liquid, iron plate and potassium persulfate, reacting at a temperature of 80-95°C and a pH value of 4.5-5.5 to obtain a mixed liquid; the iron in the iron plate reacts with potassium persulfate to generate hydroxy iron with strong oxidizing property and opens the molecular chain of the complex to react with potassium metaphosphate to generate orthophosphate; S2, cooling the mixed liquid to below 40°C, then adjusting the pH to 9.2-9.5, and then adding a first flocculant to perform a first precipitation to obtain a first supernatant; S3, adjusting the pH of the first supernatant obtained in step S2 to 9.5-9.8, then adding calcium chloride and polyaluminum chloride to mix and stir for reaction, and then continuing to add a second flocculant to perform a second precipitation to obtain a second supernatant. The treatment method proposed by the present invention can efficiently remove nickel and phosphorus through two precipitations, thereby simplifying the process of chemical nickel plating wastewater treatment technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure of the treatment device of nickel-containing waste liquid used in Examples 1-4 of the present invention and the comparative example.

[0028] Explanation of the accompanying drawings: 0, pre-reaction tank; 1, reaction tank; 2, first reaction zone; 3, second reaction zone; 4, first sedimentation zone; 5, third reaction zone; 6, fourth reaction zone; 7, fifth reaction zone; 8, second sedimentation zone; 9, first water pump; 10, second water pump; 11, power supply. DETAILED DESCRIPTION

[0029] The "range" disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60 to 120 and 80 to 110 is listed for a particular parameter, it is understood that a range of 60 to 110 and 80 to 120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In the present application, unless otherwise specified, the numerical range "a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0030] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0031] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0032] This specific embodiment provides a method for treating nickel-containing waste liquid, comprising the following steps:

[0033] S1. Mix the nickel-containing waste liquid, iron plate and potassium persulfate, and react for 30-40 minutes at a temperature of 80-95° C. and a pH value of 4.5-5.5 to obtain a mixed solution; the amount of potassium persulfate added is 3%-5% of the mass of the nickel-containing waste liquid; in some embodiments, the iron plate is a cobalt-plated iron plate, a pick-plated iron plate or a passivated iron plate;

[0034] S2, cooling the mixed solution to below 40°C, then adjusting the pH to 9.2-9.5, and then adding a first flocculant for a first precipitation for 2.5-4 hours to obtain a first supernatant; the first flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.1%-0.2%; the amount of the polyacrylamide added is 0.5%-0.8% of the volume of the mixed solution; cooling the mixed solution to below 40°C can achieve energy recovery, and the coagulation and precipitation temperature exceeds 40°C, and the precipitation effect is very poor;

[0035] S3, adjusting the pH of the first supernatant obtained in step S2 to 9.5-9.8, then adding calcium chloride and polyaluminium chloride to mix and stir for reaction, and then continuing to add a second flocculant to perform a second precipitation for 4-5 hours to obtain a second supernatant; the second flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.1%-0.2%; the amount of the polyacrylamide added is 0.2%-0.4% of the volume of the first supernatant.

[0036] This specific embodiment also provides a nickel-containing wastewater treatment device, comprising a reaction tank, a first reaction zone, a second reaction zone, a first precipitation zone, a third reaction zone, a fourth reaction zone, a fifth reaction zone and a second precipitation zone connected in sequence;

[0037] The reaction tank is used to mix the nickel-containing waste liquid, iron plate and potassium persulfate, and react at a temperature of 80 to 95° C. and a pH value of 4.5 to 5.5 to obtain a mixed solution;

[0038] The first reaction zone is used to cool the mixed solution to below 40° C., and then adjust the pH to 9.2-9.5;

[0039] The second reaction zone is used to add the first flocculant;

[0040] The first precipitation zone is used to perform a first precipitation to obtain a first supernatant;

[0041] The third reaction zone is used to adjust the pH of the first supernatant to 9.5-9.8;

[0042] The fourth reaction zone is used to add calcium chloride and polyaluminium chloride for mixed stirring reaction;

[0043] The fifth reaction zone is used to continue adding the second flocculant;

[0044] The second precipitation zone is used for performing a second precipitation.

[0045] In some embodiments, it also includes a first water pump and a second water pump, the first water pump is connected to the first sedimentation zone, and the second water pump is connected to the second sedimentation zone, the first water pump is used to pump out the sludge in the first sedimentation zone, and the second water pump is used to pump out the sludge in the second sedimentation zone; in some embodiments, it also includes further filtering and dehydrating the sludge and introducing the dehydrated water into the third reaction zone for reaction.

[0046] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0047] In the present invention, reference is made to “some embodiments”, “this embodiment”, examples, etc., which describe a subset of all possible embodiments, but it can be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0048] If similar descriptions of "first / second" appear in the application documents, the following instructions are added. In the following description, the terms "first\second\third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can be interchanged in a specific order or sequence where permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0049] In this embodiment, the term "and / or" is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, object A and / or object B may represent three situations: object A exists alone, object A and object B exist at the same time, and object B exists alone.

[0050] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0051] In the following examples or comparative examples, the amount of calcium chloride added is 160% of the total phosphorus content in the waste liquid by mass, and the amount of polyaluminium chloride added is 5% of the mass of the first supernatant.

[0052] The composition of the waste liquid treated in the following examples is shown in Table 1. The amount of waste liquid treated in each example or comparative example is 500 mL.

[0053] Table 1 Composition of nickel-containing wastewater to be treated

[0054] Table of contents pH nickel Total Phosphorus COD Total Nitrogen Numeric 4.8 5800mg / L 27500mg / L 5700mg / L 1550mg / L

[0055] The following examples 1-4 and comparative examples 1-3 use a nickel-containing wastewater treatment device to treat nickel-containing wastewater, combined with Figure 1 The device comprises a pre-reaction tank 0, a reaction tank 1, a first reaction zone 2, a second reaction zone 3, a first precipitation zone 4, a third reaction zone 5, a fourth reaction zone 6, a fifth reaction zone 7 and a second precipitation zone 8 which are connected in sequence;

[0056] Pre-reaction tank 0 is used to preliminarily heat the nickel-containing waste liquid to 80°C ± 3°C;

[0057] The reaction tank 1 is used to mix the nickel-containing waste liquid, iron plate and potassium persulfate, and react at a temperature of 80 to 95° C. and a pH value of 4.5 to 5.5 to obtain a mixed liquid;

[0058] The first reaction zone 2 is used to cool the mixed solution to below 40°C, and then adjust the pH to 9.2-9.5;

[0059] The second reaction zone 3 is used to add the first flocculant;

[0060] The first precipitation zone 4 is used to perform a first precipitation to obtain a first supernatant;

[0061] The third reaction zone 5 is used to adjust the pH of the first supernatant to 9.5-9.8;

[0062] The fourth reaction zone 6 is used to add calcium chloride and polyaluminium chloride for mixed stirring reaction;

[0063] The fifth reaction zone 7 is used to continue adding the second flocculant;

[0064] The second precipitation zone 8 is used for performing a second precipitation to obtain a second supernatant;

[0065] The device also includes a first water pump 9 and a second water pump 10, wherein the first water pump 9 is connected to the first sedimentation zone 4, and the second water pump 10 is connected to the second sedimentation zone 8, the first water pump 9 is used to extract the sludge from the first sedimentation zone 4, and the second water pump 10 is used to extract the sludge from the second sedimentation zone 8; it also includes further filtering and dehydrating the sludge and introducing the dehydrated water into the third reaction zone 5 for reaction.

[0066] The components of the device that require electricity are connected to the power source 11;

[0067] The device further comprises a heat exchange device 12, which is connected between the reaction tank 1 and the first reaction zone 2 for realizing heat recovery.

[0068] Example 1

[0069] This embodiment provides a method for treating nickel-containing waste liquid, comprising the following steps:

[0070] S1, mixing nickel-containing waste liquid, iron plate and potassium persulfate, reacting at a temperature of 85° C. and a pH value of 4.5 for 30 minutes to obtain a mixed solution; the amount of potassium persulfate added is 4% of the mass of the nickel-containing waste liquid; the iron plate is a passivated iron plate;

[0071] S2, cooling the mixed solution to below 40°C, adjusting the pH to 9.2, and then adding a first flocculant to perform a first precipitation for 2.5 hours to obtain a first supernatant; the first flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.2%; the amount of the polyacrylamide added is 0.8% of the volume of the mixed solution;

[0072] S3, adjusting the pH of the first supernatant obtained in step S2 to 9.5, then adding calcium chloride and polyaluminium chloride PAC to mix and stir for reaction, and then continuing to add a second flocculant to perform a second precipitation for 4 hours to obtain a second supernatant; the second flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.2%; the amount of the polyacrylamide added is 0.3% of the volume of the first supernatant.

[0073] Example 2

[0074] This embodiment provides a method for treating nickel-containing waste liquid, comprising the following steps:

[0075] S1, mixing nickel-containing waste liquid, iron plate and potassium persulfate, reacting at a temperature of 80° C. and a pH value of 5 for 35 minutes to obtain a mixed solution; the amount of potassium persulfate added is 4% of the mass of the nickel-containing waste liquid; the iron plate is a cobalt electroplated iron plate;

[0076] S2, cooling the mixed solution to below 40°C, adjusting the pH to 9.3, and then adding a first flocculant to perform a first precipitation for 3 hours to obtain a first supernatant; the first flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.1%; the amount of the polyacrylamide added is 0.5% of the volume of the mixed solution;

[0077] S3, adjusting the pH of the first supernatant obtained in step S2 to 9.6, then adding calcium chloride and polyaluminium chloride PAC to mix and stir for reaction, and then continuing to add a second flocculant to perform a second precipitation for 4 hours to obtain a second supernatant; the second flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.1%; the amount of the polyacrylamide added is 0.3% of the volume of the first supernatant.

[0078] Example 3

[0079] This embodiment provides a method for treating nickel-containing waste liquid, comprising the following steps:

[0080] S1, mixing nickel-containing waste liquid, iron plate and potassium persulfate, reacting at a temperature of 95° C. and a pH value of 5 for 40 minutes to obtain a mixed solution; the amount of potassium persulfate added is 5% of the mass of the nickel-containing waste liquid; the iron plate is an electroplating pick iron plate;

[0081] S2, cooling the mixed solution to below 40°C, adjusting the pH to 9.5, and then adding a first flocculant to perform a first precipitation for 4 hours to obtain a first supernatant; the first flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.1%; the amount of the polyacrylamide added is 0.6% of the volume of the mixed solution;

[0082] S3, adjusting the pH of the first supernatant obtained in step S2 to 9.8, then adding calcium chloride and polyaluminium chloride PAC to mix and stir for reaction, and then continuing to add a second flocculant to perform a second precipitation for 5 hours to obtain a second supernatant; the second flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.1%; the amount of the polyacrylamide added is 0.4% of the volume of the first supernatant.

[0083] Example 4

[0084] This embodiment provides a method for treating nickel-containing waste liquid, comprising the following steps:

[0085] S1, mixing nickel-containing waste liquid, iron plate and potassium persulfate, reacting at a temperature of 90° C. and a pH value of 5.5 for 35 minutes to obtain a mixed solution; the amount of potassium persulfate added is 3% of the mass of the nickel-containing waste liquid; the iron plate is a passivated iron plate;

[0086] S2, cooling the mixed solution to below 40°C, adjusting the pH to 9.3, and then adding a first flocculant to perform a first precipitation for 3 hours to obtain a first supernatant; the first flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.2%; the amount of the polyacrylamide added is 0.7% of the volume of the mixed solution;

[0087] S3, adjusting the pH of the first supernatant obtained in step S2 to 9.6, then adding calcium chloride and polyaluminium chloride PAC to mix and stir for reaction, and then continuing to add the second flocculant to carry out a second precipitation for 4.5 hours to obtain a second supernatant; the second flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.2%; the amount of the polyacrylamide added is 0.3% of the volume of the first supernatant.

[0088] Comparative Example 1

[0089] This comparative example proposes a method for treating nickel-containing waste liquid, which is different from Example 1 in that only calcium chloride is added in step S3 without adding polyaluminium chloride, and comprises the following steps:

[0090] S1, mixing nickel-containing waste liquid, iron plate and potassium persulfate, reacting at a temperature of 85° C. and a pH value of 4.5 for 30 minutes to obtain a mixed solution; the amount of potassium persulfate added is 4% of the mass of the nickel-containing waste liquid; the iron plate is a passivated iron plate;

[0091] S2, cooling the mixed solution to below 40°C, adjusting the pH to 9.2, and then adding a first flocculant to perform a first precipitation for 2.5 hours to obtain a first supernatant; the first flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.2%; the amount of the polyacrylamide added is 0.8% of the volume of the mixed solution;

[0092] S3, adjusting the pH of the first supernatant obtained in step S2 to 9.5, then adding calcium chloride to mix and stir for reaction, and then continuing to add the second flocculant to carry out a second precipitation for 4 hours to obtain a second supernatant; the second flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.2%; the amount of the polyacrylamide added is 0.3% of the volume of the first supernatant; the amount of polyaluminium chloride in Example 1 is supplemented with an equal amount of calcium chloride.

[0093] Comparative Example 2

[0094] This comparative example proposes a method for treating nickel-containing waste liquid, which is different from Example 1 in that only polyaluminium chloride is added in step S3 without adding calcium chloride, and comprises the following steps:

[0095] S1, mixing nickel-containing waste liquid, iron plate and potassium persulfate, reacting at a temperature of 85° C. and a pH value of 4.5 for 30 minutes to obtain a mixed solution; the amount of potassium persulfate added is 4% of the mass of the nickel-containing waste liquid; the iron plate is a passivated iron plate;

[0096] S2, cooling the mixed solution to below 40°C, adjusting the pH to 9.2, and then adding a first flocculant to perform a first precipitation for 2.5 hours to obtain a first supernatant; the first flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.2%; the amount of the polyacrylamide added is 0.8% of the volume of the mixed solution;

[0097] S3, adjusting the pH of the first supernatant obtained in step S2 to 9.5, then adding polyaluminium chloride to mix and stir for reaction, and then continuing to add the second flocculant to carry out a second precipitation for 4 hours to obtain a second supernatant; the second flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.2%; the amount of polyacrylamide added is 0.3% of the volume of the first supernatant; the amount of calcium chloride in Example 1 is supplemented with an equal amount of polyaluminium chloride.

[0098] Comparative Example 3

[0099] This comparative example proposes a method for treating nickel-containing waste liquid, which is different from Example 1 in that no polyaluminium chloride and calcium chloride are added in step S3, and comprises the following steps:

[0100] S1, mixing nickel-containing waste liquid, iron plate and potassium persulfate, reacting at a temperature of 85° C. and a pH value of 4.5 for 30 minutes to obtain a mixed solution; the amount of potassium persulfate added is 4% of the mass of the nickel-containing waste liquid; the iron plate is a passivated iron plate;

[0101] S2, cooling the mixed solution to below 40°C, adjusting the pH to 9.2, and then adding a first flocculant to perform a first precipitation for 2.5 hours to obtain a first supernatant; the first flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.2%; the amount of the polyacrylamide added is 0.8% of the volume of the mixed solution;

[0102] S3, adjusting the pH of the first supernatant obtained in step S2 to 9.5, and then continuing to add the second flocculant to perform a second precipitation for 4 hours to obtain a second supernatant; the second flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.2%; the amount of the polyacrylamide added is 0.3% of the volume of the first supernatant.

[0103] The components and contents in the first supernatant after treatment in Example 1-4 and the second supernatant after treatment in Example 1-4 and Comparative Example 1-3 were detected, and the results are shown in Table 2 and Table 3.

[0104] Table 2 Components and contents of the first supernatant after treatment in Examples 1-4

[0105] nickel Total Phosphorus COD Total Nitrogen Example 1 10mg / L 25mg / L 650mg / L 1300mg / L Example 2 10.5mg / L 26.2mg / L 652mg / L 1350mg / L Example 3 11mg / L 25.8mg / L 654mg / L 1324mg / L Example 4 9.8mg / L 25.4mg / L 648mg / L 1345mg / L

[0106] Table 3 Components and contents of the second clear solution after treatment in Examples 1-4 and Comparative Examples 1-3

[0107] nickel Total Phosphorus COD Total Nitrogen Example 1 0.8mg / L 2.7mg / L 630mg / L 1280mg / L Example 2 0.9mg / L 2.9mg / L 641mg / L 1302mg / L Example 3 1.1mg / L 3.2mg / L 642mg / L 1295mg / L Example 4 0.8mg / L 2.6mg / L 635mg / L 1315mg / L Comparative Example 1 4.6mg / L 15.6mg / L 645mg / L 1290mg / L Comparative Example 2 4.1mg / L 14.7mg / L 643mg / L 1285mg / L Comparative Example 3 6.8mg / L 19.3mg / L 647mg / L 1292mg / L

[0108] Combining Table 2 and Table 3, it can be seen that after two precipitation treatments, nickel ions are effectively removed in the treatment method proposed in the present invention, and total phosphorus is removed by physicochemical precipitation by converting metaphosphate into phosphate and reacting with calcium ions, and the one-step reaction achieves a dual purpose.

[0109] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for treating nickel-containing waste liquid, characterized in that: The following steps are involved: S1, mixing nickel-containing waste liquid, iron plate and potassium persulfate, reacting at a temperature of 80-95° C. and a pH value of 4.5-5.5 to obtain a mixed solution; the amount of potassium persulfate added is 3%-5% of the mass of the nickel-containing waste liquid; and the reaction time is 30-40 minutes; S2, cooling the mixed solution to below 40° C., adjusting the pH to 9.2-9.5, and then adding a first flocculant to perform a first precipitation to obtain a first supernatant; the first flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.1%-0.2%; S3, adjusting the pH of the first supernatant obtained in step S2 to 9.5-9.8, then adding calcium chloride and polyaluminium chloride to mix and stir for reaction, and then continuing to add a second flocculant for a second precipitation to obtain a second supernatant; the second flocculant is polyacrylamide, and the mass concentration of the polyacrylamide is 0.1%-0.2%; the amount of the polyacrylamide added is 0.2%-0.4% of the volume of the first supernatant.

2. The method for treating nickel-containing waste liquid according to claim 1, wherein: In step S1, the iron plate is a cobalt-plated iron plate, a pick-plated iron plate or a passivated iron plate.

3. The method for treating nickel-containing waste liquid according to claim 1, characterized in that: In step S2, the amount of polyacrylamide added is 0.5%-0.8% of the volume of the mixed solution.

4. The method for treating nickel-containing waste liquid according to claim 1, wherein: In step S2, the first precipitation time is 2.5-4 hours.

5. The method for treating nickel-containing waste liquid according to claim 1, characterized in that: In step S3, the second precipitation time is 4-5 hours.

6. A nickel-containing wastewater treatment device, characterized in that: The method for treating the nickel-containing waste liquid according to any one of claims 1 to 5 is used for treatment, comprising a reaction tank, a first reaction zone, a second reaction zone, a first precipitation zone, a third reaction zone, a fourth reaction zone, a fifth reaction zone and a second precipitation zone connected in sequence; The reaction tank is used to mix the nickel-containing waste liquid, iron plate and potassium persulfate, and react at a temperature of 80 to 95° C. and a pH value of 4.5 to 5.5 to obtain a mixed solution; The first reaction zone is used to cool the mixed solution to below 40° C., and then adjust the pH to 9.2-9.5; The second reaction zone is used to add the first flocculant; The first precipitation zone is used to perform a first precipitation to obtain a first supernatant; The third reaction zone is used to adjust the pH of the first supernatant to 9.5-9.8; The fourth reaction zone is used to add calcium chloride and polyaluminium chloride for mixed stirring reaction; The fifth reaction zone is used to continue adding the second flocculant; The second precipitation zone is used for performing a second precipitation.

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