Treatment method of nickel-containing wastewater

Abstract

The invention provides a nickel-containing wastewater treatment method. The nickel-containing wastewater treatment method comprises the following steps: pretreatment, primary coagulation treatment, sludge treatment, secondary coagulation treatment, discharge treatment and accident treatment. The pretreatment comprises an adjusting tank and a pH adjusting tank; and the coagulation treatment comprises an oxidation tank, a coagulation reaction tank and an inclined tube sedimentation tank. According to the method, two-stage coagulation is adopted, silicon dioxide xerogel, modified polyaluminum chloride and modified polyacrylamide are used as coagulants step by step, and the removal capacity of nickel-containing pollutants with different sizes and properties is enhanced. The silicon dioxide xerogel prepared by the method disclosed by the invention has high specific surface area, good pore structure and relatively high stability, and due to the properties, the silicon dioxide xerogel has relatively high adsorption capacity and filtering effect in nickel-containing wastewater treatment. Polyaluminum chloride and polyacrylamide are modified, and a kapok fiber hydrophobic functional group is introduced, so that the hydrophobicity is further improved, and the burden of a sludge treatment process is reduced.

Description

Technical Field

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

[0002] Nickel and its metal oxides are widely used in electroplating, chemical industry, smelting and other fields due to their good physical properties, which has brought great benefits to human life. However, nickel-containing wastewater will be produced in the process of nickel application. Nickel, as a heavy metal, cannot be degraded by organisms in the natural environment. After being ingested by humans or animals through the food chain, metallic nickel will accumulate in the body and inhibit the human enzyme system. In the early stage of ingestion, it will cause dizziness and headache. Long-term excessive intake will affect the central nervous system and cause mental disorder. Improper treatment of nickel-containing wastewater will not only cause environmental pollution but also affect human health. Therefore, nickel-containing wastewater must be treated to meet national standards before it can be discharged. Common treatment methods for nickel-containing wastewater are divided into traditional chemical methods, physical methods and electrochemical methods. Traditional chemical methods can be divided into chemical precipitation and coagulation methods. Physical methods can be divided into adsorption, ion exchange and membrane separation. Electrochemical methods can be divided into electrodialysis and membrane separation. Among them, coagulation has the characteristics of simple process, easy operation and low cost compared with other treatment methods, so it is widely used. The existing coagulation method is mostly a primary coagulation treatment, and it is difficult to meet the discharge standard of total nickel content ≤ 0.1 mg / L after coagulation treatment. The existing coagulants have low nickel removal rates and unstable nickel removal effects. At the same time, the water content of the sludge produced after coagulation is as high as 98%, which puts a heavy burden on the subsequent sludge treatment process. Summary of the invention

[0003] In view of this, the present invention proposes a method for treating nickel-containing wastewater to solve the above problems.

[0004] The technical solution of the present invention is achieved in this way:

[0005] A method for treating nickel-containing wastewater includes the following steps: pretreatment, primary coagulation treatment, sludge treatment, secondary coagulation treatment, discharge treatment and accident treatment; the method specifically includes the following steps:

[0006] S1: Pretreatment: including a regulating tank and a pH adjustment tank. Alkaline agent is added to the pH adjustment tank to adjust the pH to 8-9.

[0007] S2: Primary coagulation treatment: including primary oxidation tank, primary coagulation reaction tank and primary inclined tube sedimentation tank; adding oxidant 1 to the primary oxidation tank for oxidation reaction and staying for 2.0-3.0h; then adding coagulant 1 to the primary coagulation reaction tank for coagulation reaction and staying for 140-150min; then discharging into the primary inclined tube sedimentation tank and staying for 50-70min.

[0008] Sludge treatment:

[0009] S3: Sludge treatment: The nickel-containing sludge formed after the first-level inclined tube sedimentation is discharged into the sludge pool; a plate and frame filter press is set up, and the nickel sludge after filtration is transported to a designated agency for recycling. The filtrate from the filtration is discharged into the clear water pool if it is qualified, and discharged into the secondary oxidation pool if it is unqualified for further treatment.

[0010] S4: Secondary coagulation treatment: including secondary oxidation tank, secondary coagulation reaction tank, secondary inclined tube sedimentation tank; nickel-containing wastewater after primary coagulation treatment and sludge treatment is discharged into the secondary oxidation tank, oxidant 2 is added to the secondary oxidation tank for oxidation reaction, and the reaction time is 1.5-2.0 hours; then coagulant 2 is added to the secondary coagulation reaction tank for coagulation reaction, and the reaction time is 50-60 minutes; then coagulant 3 is added for coagulation reaction, and the reaction time is 45-50 minutes; then the wastewater is discharged into the secondary inclined tube sedimentation tank, and the reaction time is 40-60 minutes.

[0011] S5: Discharge treatment: The clear liquid after secondary coagulation treatment is discharged into the clear water tank; if it passes the test, it will flow into the plant water system through the pipeline for continued use, and if it fails the test, it will flow into the accident emergency tank; the nickel-containing sludge formed after the secondary inclined tube sedimentation is discharged into the sludge tank and the nickel-containing sludge is treated according to S3.

[0012] Furthermore, an accident emergency pool is set up. When the effluent is unqualified due to sudden factors or human factors, the nickel-containing wastewater is discharged into the accident emergency pool and then discharged to the regulating pool for treatment.

[0013] Furthermore, the regulating tank, pH adjustment tank, primary oxidation tank, primary coagulation reaction tank, primary inclined tube sedimentation tank, sludge tank, secondary oxidation tank, secondary coagulation reaction tank, secondary inclined tube sedimentation tank, and clear water tank are connected in sequence and are all reinforced structures with an anti-corrosion layer inside, and the anti-corrosion layer is made of anti-corrosion plates.

[0014] Furthermore, a stirrer is provided between the primary coagulation reaction tank and the secondary coagulation reaction tank, and the stirrer has a power of 500-1000W and a stirring speed of 50-70r / min.

[0015] Furthermore, the alkaline agent in S1 is one of sodium hydroxide and calcium hydroxide.

[0016] Furthermore, the oxidant 1 in S2 is calcium oxide, and the amount added is 50-60 g / m 3 .

[0017] Furthermore, the coagulant 1 in S2 is silica xerogel, and the added amount is 35-45 g / m 3 , the silicon dioxide xerogel is prepared by the following steps:

[0018] S21: piperidine and aqueous ammonia: piperidine with a concentration of 1-10 wt % and aqueous ammonia with a concentration of 15-20 wt % are mixed, and stirred for 1-3 min, wherein the volume ratio of piperidine to aqueous ammonia is (1-1.2):(1-1.5), to obtain solution A for standby use;

[0019] S22: dissolving tetraethyl orthosilicate: adding tetraethyl orthosilicate to solution A, stirring for 10-20 min, and stopping stirring when the solution turns milky white to obtain a silica gel solution; the mass volume ratio of tetraethyl orthosilicate to solution A is (0.8-1.2):(2-3);

[0020] S23: Aging and drying: Aging the silica gel solution at room temperature for 1-1.2 hours, then placing it in an aging box at 75-85°C for further aging for 3.5-4.5 hours, taking it out and leaving it in the air at room temperature for 13-15 hours, then placing it in a dryer at 75-85°C for 3.5-4.5 hours to obtain a silica xerogel.

[0021] Furthermore, the oxidant 2 in S4 is hydrogen peroxide, and the amount added is 300-600 ml / m 3 .

[0022] Furthermore, the coagulant 2 in S4 is modified polyaluminium chloride, and the amount of modified polyaluminium chloride added is 100-300 mg / m 3 The modified polyaluminium chloride is prepared by the following method: 8-10 parts by mass of polyaluminium chloride and 2-4 parts of kapok fiber are added to 20-24 parts of a solvent, and stirred for 2-5 minutes to obtain a solution C; the solution C is placed in an ultrasonic device for ultrasonic oscillation treatment for 20-30 minutes, the ultrasonic power is controlled at 1000-1500W, and the ultrasonic frequency is controlled at 15-20Hz to obtain a solution D; the solution D is placed in a centrifuge and rotated at 7000-9000r / min for 5-10 minutes to separate a modified polyaluminium chloride solution; the modified polyaluminium chloride solution is placed in a dryer and dried at 50-60°C for 20-24 hours to obtain a modified polyaluminium chloride.

[0023] Furthermore, the coagulant 3 in S4 is modified polyacrylamide, and the amount of modified polyacrylamide added is 20-40 mg / m 3The modified polyacrylamide is prepared by the following method: taking 7-9 parts of polyacrylamide and 2-3 parts of kapok fiber by weight, adding the mixture into 18-26 parts of a solvent, stirring for 2-5 minutes, and obtaining a solution E; placing the solution E in an ultrasonic device for ultrasonic oscillation treatment for 20-30 minutes, with the ultrasonic power controlled at 1000-1500W and the ultrasonic frequency controlled at 15-20Hz, and obtaining a solution F; placing the solution F in a centrifuge and rotating it at 7000-9000r / min for 5-10 minutes to obtain a modified polyacrylamide solution; placing the modified polyacrylamide solution in a dryer and drying it at 50-55°C for 18-20 hours to obtain a modified polyacrylamide.

[0024] Furthermore, the dissolving agent is prepared by mixing 1.5-2.5 parts of zinc oxide, 6-8 parts of sodium hydroxide, 13-14 parts of urea and 70-80 parts of pure water and stirring for 1-3 minutes, and then placed in an insulated box at an insulated temperature of -10°C to -15°C for 20-25 minutes to obtain the dissolving agent.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention enhances the removal capacity of nickel-containing pollutants of different sizes and properties through two-stage coagulation treatment. In the first stage coagulation treatment, larger suspended and colloidal nickel-containing pollutants are removed, while in the second stage coagulation treatment, smaller nickel-containing pollutants can be removed more effectively. This two-stage treatment method can more comprehensively remove various pollutants in nickel-containing wastewater. The reaction conditions of piperidine and ammonia water in the present invention are mild, and the prepared silica dry gel has a high specific surface area, a good pore structure and high stability. These properties make the silica dry gel have a high adsorption capacity and filtering effect in the treatment of nickel-containing wastewater, and can effectively remove heavy metal ions and organic pollutants in nickel-containing wastewater. At the same time, the silica dry gel is easier to transport and store than wet silica gel. The present invention introduces kapok fiber hydrophobic functional groups into polyaluminum chloride and polyacrylamide by modifying polyaluminum chloride and polyacrylamide, further improving their hydrophobicity, reducing the water content in the sludge from 98% to 60%, and reducing the burden of subsequent processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a process flow chart of nickel-containing wastewater treatment. DETAILED DESCRIPTION

[0027] In order to better understand the technical content of the present invention, specific embodiments are provided below to further illustrate the present invention.

[0028] Unless otherwise specified, the experimental methods used in the embodiments of the present invention are all conventional methods.

[0029] Unless otherwise specified, the materials, reagents, etc. used in the embodiments of the present invention can be obtained from commercial sources.

[0030] Example 1

[0031] A method for treating nickel-containing wastewater specifically comprises the following steps:

[0032] The factory's nickel-containing wastewater is discharged into the regulating pond for water quality and quantity balance and stays there for 10.5 hours.

[0033] Next, it is discharged into the pH adjustment tank, sodium hydroxide is added to adjust the pH to 8, and the solution is retained for 70 minutes.

[0034] Next, it was discharged into the primary oxidation tank and 50g / m 3 Calcium oxide undergoes oxidation reaction and stays for 2.0 hours.

[0035] Next, it was discharged into the primary coagulation reaction tank and 35g / m 3 The silica xerogel was subjected to coagulation reaction and stayed for 140 min.

[0036] Next, it is discharged into the primary inclined tube sedimentation tank and stays for 50 minutes.

[0037] Next, it is discharged into the sludge pool, and a plate and frame filter press is set up. The nickel sludge after filtration is transported to a designated agency for recycling. The filtrate from the filtration is discharged into the clear water pool if it passes the test, and discharged into the secondary oxidation pool for further treatment if it fails the test.

[0038] Next, discharge into the secondary oxidation tank and add 300ml / m 3 The hydrogen peroxide was oxidized for 1.5 hours.

[0039] Next, the water was discharged into the secondary coagulation reaction tank and 100 mg / m 3 The modified polyaluminium chloride is subjected to a coagulation reaction and stays for 50 minutes; the modified polyaluminium chloride is prepared by the following method: 1.5 parts of zinc oxide, 6 parts of sodium hydroxide, 13 parts of urea, and 70 parts of pure water are mixed and stirred for 1 minute, and then placed in an incubator, and a solvent is obtained under the conditions of an insulation temperature of -10°C and insulation for 20 minutes. 8 parts of polyaluminium chloride and 2 parts of kapok fiber are taken by mass, and the mixture is added to 20 parts of the solvent, stirred for 2 minutes, and a solution C is obtained; the solution C is placed in an ultrasonic device for ultrasonic oscillation treatment for 20 minutes, the ultrasonic power is controlled at 1000W, and the ultrasonic frequency is controlled at 15Hz, and a solution D is obtained; the solution D is placed in a centrifuge and rotated at 7000r / min for 5 minutes to separate a modified polyaluminium chloride solution; the modified polyaluminium chloride solution is placed in a dryer and dried at 50°C for 20 hours to obtain a modified polyaluminium chloride.

[0040] Next, add 20 mg / m 3 The modified polyacrylamide was subjected to coagulation reaction and stayed for 45 minutes; the modified polyacrylamide was prepared by the following method: 1.5 parts of zinc oxide, 6 parts of sodium hydroxide, 13 parts of urea, and 70 parts of pure water were mixed and stirred for 1 minute, and then placed in an incubator, and a solvent was obtained at a temperature of -10°C and a temperature of 20 minutes. 7 parts of polyacrylamide and 2 parts of kapok fiber were taken by mass, and the mixture was added to 18 parts of the solvent, stirred for 2 minutes, and a solution E was obtained; the solution E was placed in an ultrasonic device for ultrasonic oscillation treatment for 20 minutes, the ultrasonic power was controlled at 1000W, and the ultrasonic frequency was controlled at 15Hz, and a solution F was obtained; the solution F was placed in a centrifuge and rotated at 7000r / min for 5 minutes to obtain a modified polyacrylamide solution; the modified polyacrylamide solution was placed in a dryer and dried at 50°C for 18 hours to obtain a modified polyacrylamide.

[0041] Next, it is discharged into the secondary inclined tube sedimentation tank and stays for 40 minutes.

[0042] Next, it is discharged into the clean water tank and stays for 1.0 hour; if it passes the test, it will flow into the factory water system through the pipeline for continued use, and if it fails the test, it will flow into the accident emergency tank; the nickel-containing sludge formed after the secondary inclined tube sedimentation is discharged into the above-mentioned sludge tank and treated according to the above-mentioned sludge treatment steps.

[0043] The above-mentioned regulating tank, pH adjustment tank, primary oxidation tank, primary coagulation reaction tank, primary inclined tube sedimentation tank, sludge tank, secondary oxidation tank, secondary coagulation reaction tank, secondary inclined tube sedimentation tank, clear water tank and accident emergency tank are reinforced steel structures with an anti-corrosion layer inside, which is spliced ​​from anti-corrosion plates.

[0044] A stirrer is provided between the primary coagulation reaction tank and the secondary coagulation reaction tank. The stirrer has a power of 500W and a stirring speed of 50r / min.

[0045] Example 2

[0046] A method for treating nickel-containing wastewater specifically comprises the following steps:

[0047] The factory's nickel-containing wastewater is discharged into the regulating pond for water quality and quantity balance and stays there for 11 hours.

[0048] Next, it is discharged into the pH adjustment tank, sodium hydroxide is added to adjust the pH to 9, and the water is retained for 80 minutes.

[0049] Next, it was discharged into the primary oxidation tank and 60g / m 3 Calcium oxide undergoes oxidation reaction and stays for 3.0 hours.

[0050] Next, it was discharged into the primary coagulation reaction tank and 45g / m3 The silica xerogel was subjected to coagulation reaction and stayed for 150 minutes.

[0051] Next, it is discharged into the primary inclined tube sedimentation tank and stays there for 70 minutes.

[0052] Next, it is discharged into the sludge pool, and a plate and frame filter press is set up. The nickel sludge after filtration is transported to a designated agency for recycling. The filtrate from the filtration is discharged into the clear water pool if it passes the test, and discharged into the secondary oxidation pool for further treatment if it fails the test.

[0053] Next, discharge into the secondary oxidation tank and add 600ml / m 3 The hydrogen peroxide undergoes oxidation reaction and stays for 2.0 hours.

[0054] Next, it was discharged into the secondary coagulation reaction tank and 300 mg / m 3 The modified polyaluminium chloride is subjected to a coagulation reaction and stays for 60 minutes; the modified polyaluminium chloride is prepared by the following method: 2.5 parts of zinc oxide, 8 parts of sodium hydroxide, 14 parts of urea, and 80 parts of pure water are mixed and stirred for 3 minutes, and then placed in an incubator, and a solvent is obtained at a temperature of -15°C and a temperature of 25 minutes. 10 parts of polyaluminium chloride and 4 parts of kapok fiber are taken by mass, and the mixture is added to 24 parts of the solvent, stirred for 5 minutes, and a solution C is obtained; the solution C is placed in an ultrasonic device for ultrasonic oscillation treatment for 30 minutes, the ultrasonic power is controlled at 1500W, and the ultrasonic frequency is controlled at 20Hz, to obtain a solution D; the solution D is placed in a centrifuge and rotated at 9000r / min for 10 minutes to separate the modified polyaluminium chloride solution; the modified polyaluminium chloride solution is placed in a dryer and dried at 60°C for 24 hours to obtain a modified polyaluminium chloride.

[0055] Next, add 40 mg / m 3 The modified polyacrylamide was subjected to coagulation reaction and stayed for 50 minutes; the modified polyacrylamide was prepared by the following method: 2.5 parts of zinc oxide, 8 parts of sodium hydroxide, 14 parts of urea, and 80 parts of pure water were mixed and stirred for 3 minutes, and then placed in an incubator, and a solvent was obtained at an insulation temperature of -15°C and an insulation temperature of 25 minutes. 9 parts of polyacrylamide and 3 parts of kapok fiber were taken by mass, and the mixture was added to 26 parts of the solvent and stirred for 5 minutes to obtain solution E; solution E was placed in an ultrasonic device for ultrasonic oscillation treatment for 30 minutes, with the ultrasonic power controlled at 1500W and the ultrasonic frequency controlled at 20Hz to obtain solution F; solution F was placed in a centrifuge and rotated at 9000r / min for 10 minutes to obtain a modified polyacrylamide solution; the modified polyacrylamide solution was placed in a dryer and dried at 55°C for 20 hours to obtain a modified polyacrylamide.

[0056] Next, it is discharged into the secondary inclined tube sedimentation tank and stays for 60 minutes.

[0057] Next, it is discharged into the clean water tank and stays for 2.0 hours; if it passes the test, it will flow into the factory water system through the pipeline for continued use, and if it fails the test, it will flow into the accident emergency tank; the nickel-containing sludge formed after the secondary inclined tube sedimentation is discharged into the above-mentioned sludge tank and treated according to the above-mentioned sludge treatment steps.

[0058] The above-mentioned regulating tank, pH adjustment tank, primary oxidation tank, primary coagulation reaction tank, primary inclined tube sedimentation tank, sludge tank, secondary oxidation tank, secondary coagulation reaction tank, secondary inclined tube sedimentation tank, clear water tank and accident emergency tank are reinforced steel structures with an anti-corrosion layer inside, which is spliced ​​from anti-corrosion plates.

[0059] A stirrer is provided between the primary coagulation reaction tank and the secondary coagulation reaction tank. The stirrer has a power of 1000W and a stirring speed of 70r / min.

[0060] The silicon dioxide xerogel in the above-mentioned embodiment 1 and embodiment 2 is prepared by the following steps:

[0061] S21: piperidine and aqueous ammonia: piperidine with a concentration of 1 wt % and aqueous ammonia with a concentration of 15 wt % were mixed, and stirred for 1 min, wherein the volume ratio of piperidine to aqueous ammonia was 1:1, to obtain solution A for standby use;

[0062] S22: dissolving tetraethyl orthosilicate: adding tetraethyl orthosilicate to solution A, stirring for 10 minutes, and stopping stirring when the solution turns milky white, to obtain a silica gel solution; the mass volume ratio of tetraethyl orthosilicate to solution A is 0.8:2;

[0063] S23: Aging and drying: The silica gel solution was aged at room temperature for 1 hour, then placed in an aging box at 75°C for further aging for 3.5 hours, taken out and left in the air at room temperature for 13 hours, then placed in a dryer at 75°C for drying for 3.5 hours to obtain a silica dry gel.

[0064] Example 3

[0065] A method for treating nickel-containing wastewater specifically comprises the following steps:

[0066] The factory's nickel-containing wastewater is discharged into the regulating pond for water quality and quantity balance, and stays there for 10.7 hours.

[0067] Next, it is discharged into the pH adjustment tank, sodium hydroxide is added to adjust the pH to 8.5, and the solution is retained for 75 minutes.

[0068] Next, it was discharged into the primary oxidation tank and 55g / m 3 Calcium oxide undergoes oxidation reaction and stays for 2.5 hours.

[0069] Next, it was discharged into the primary coagulation reaction tank and 30g / m 3 The silica xerogel was subjected to coagulation reaction and stayed for 145 min.

[0070] Next, it is discharged into the primary inclined tube sedimentation tank and stays for 60 minutes.

[0071] Next, it is discharged into the sludge pool, and a plate and frame filter press is set up. The nickel sludge after filtration is transported to a designated agency for recycling. The filtrate from the filtration is discharged into the clear water pool if it passes the test, and discharged into the secondary oxidation pool for further treatment if it fails the test.

[0072] Next, discharge into the secondary oxidation tank and add 450ml / m 3 The hydrogen peroxide undergoes an oxidation reaction and stays for 1.7 hours.

[0073] Next, it was discharged into the secondary coagulation reaction tank and 200 mg / m 3 The modified polyaluminium chloride is subjected to a coagulation reaction and stays for 55 minutes; the modified polyaluminium chloride is prepared by the following method: 2.0 parts of zinc oxide, 7 parts of sodium hydroxide, 13.5 parts of urea, and 75 parts of pure water are mixed and stirred for 2 minutes, and then placed in an incubator, and a solvent is obtained under the conditions of an insulation temperature of -12.5°C and insulation for 22.5 minutes. 9 parts of polyaluminium chloride and 3 parts of kapok fiber are taken by mass, and the mixture is added to 22 parts of the solvent, stirred for 3.5 minutes, and a solution C is obtained; the solution C is placed in an ultrasonic device for ultrasonic oscillation treatment for 25 minutes, the ultrasonic power is controlled at 1250W, and the ultrasonic frequency is controlled at 17.5Hz, and a solution D is obtained; the solution D is placed in a centrifuge and rotated at 8000r / min for 7.5 minutes to separate a modified polyaluminium chloride solution; the modified polyaluminium chloride solution is placed in a dryer and dried at 55°C for 22 hours to obtain a modified polyaluminium chloride.

[0074] Next, add 30 mg / m 3The modified polyacrylamide was subjected to coagulation reaction and stayed for 47.5 minutes; the modified polyacrylamide was prepared by the following method: 2.0 parts of zinc oxide, 7 parts of sodium hydroxide, 13.5 parts of urea, and 75 parts of pure water were mixed and stirred for 2 minutes, and then placed in an incubator, and a solvent was obtained at an insulation temperature of -12.5°C and an insulation temperature of 22.5 minutes. 8 parts of polyacrylamide and 2.5 parts of kapok fiber were taken by mass, and the mixture was added to 22 parts of the solvent and stirred for 3.5 minutes to obtain solution E; solution E was placed in an ultrasonic device for ultrasonic oscillation treatment for 25 minutes, with the ultrasonic power controlled at 1250W and the ultrasonic frequency controlled at 17.5Hz to obtain solution F; solution F was placed in a centrifuge and rotated at 8000r / min for 7.5 minutes to obtain a modified polyacrylamide solution; the modified polyacrylamide solution was placed in a dryer and dried at 52.5°C for 19 hours to obtain modified polyacrylamide.

[0075] Next, it is discharged into the secondary inclined tube sedimentation tank and stays for 50 minutes.

[0076] Next, it is discharged into the clean water tank and stays for 1.5 hours; if it passes the test, it will flow into the factory water system through the pipeline for continued use, and if it fails the test, it will flow into the accident emergency tank; the nickel-containing sludge formed after the secondary inclined tube sedimentation is discharged into the above-mentioned sludge tank and treated according to the above-mentioned sludge treatment steps.

[0077] The above-mentioned regulating tank, pH adjustment tank, primary oxidation tank, primary coagulation reaction tank, primary inclined tube sedimentation tank, sludge tank, secondary oxidation tank, secondary coagulation reaction tank, secondary inclined tube sedimentation tank, clear water tank and accident emergency tank are reinforced steel structures with an anti-corrosion layer inside, which is spliced ​​from anti-corrosion plates.

[0078] A stirrer is provided between the primary coagulation reaction tank and the secondary coagulation reaction tank. The stirrer has a power of 750W and a stirring speed of 60r / min.

[0079] Next, the above-mentioned silica xerogel is prepared by the following steps:

[0080] S21: piperidine and aqueous ammonia: piperidine with a concentration of 5.5 wt % and aqueous ammonia with a concentration of 17.5 wt % were mixed, and stirred for 2 min, wherein the volume ratio of piperidine to aqueous ammonia was 1.1:1.3, to obtain solution A for standby use;

[0081] S22: dissolving tetraethyl orthosilicate: adding tetraethyl orthosilicate into solution A, stirring for 15 minutes, and stopping stirring when the solution turns milky white, to obtain a silica gel solution; the mass volume ratio of tetraethyl orthosilicate to solution A is 1.0:2.5;

[0082] S23: Aging and drying: The silica gel solution was aged at room temperature for 1.1 h, then placed in an aging box at 80°C for further aging for 4.0 h, taken out and left in the air at room temperature for 14 h, then placed in a dryer and dried at 80°C for 4.0 h to obtain a silica dry gel.

[0083] Example 4

[0084] A method for treating nickel-containing wastewater specifically comprises the following steps:

[0085] The factory's nickel-containing wastewater is discharged into the regulating pond for water quality and quantity balance and stays there for 10.5 hours.

[0086] Next, it is discharged into the pH adjustment tank, calcium hydroxide is added to adjust the pH to 8, and the water is retained for 70 minutes.

[0087] Next, it was discharged into the primary oxidation tank and 50g / m 3 Calcium oxide undergoes oxidation reaction and stays for 2.0 hours.

[0088] Next, it was discharged into the primary coagulation reaction tank and 35g / m 3 The silica xerogel was subjected to coagulation reaction and stayed for 140 min.

[0089] Next, it is discharged into the primary inclined tube sedimentation tank and stays for 50 minutes.

[0090] Next, it is discharged into the sludge pool, and a plate and frame filter press is set up. The nickel sludge after filtration is transported to a designated agency for recycling. The filtrate from the filtration is discharged into the clear water pool if it passes the test, and discharged into the secondary oxidation pool for further treatment if it fails the test.

[0091] Next, discharge into the secondary oxidation tank and add 300ml / m 3 The hydrogen peroxide was oxidized for 1.5 hours.

[0092] Next, the water was discharged into the secondary coagulation reaction tank and 100 mg / m 3The modified polyaluminium chloride is subjected to a coagulation reaction and stays for 50 minutes; the modified polyaluminium chloride is prepared by the following method: 1.5 parts of zinc oxide, 6 parts of sodium hydroxide, 13 parts of urea, and 70 parts of pure water are mixed and stirred for 1 minute, and then placed in an incubator, and a solvent is obtained under the conditions of an insulation temperature of -10°C and insulation for 20 minutes. 8 parts of polyaluminium chloride and 2 parts of kapok fiber are taken by mass, and the mixture is added to 20 parts of the solvent, stirred for 2 minutes, and a solution C is obtained; the solution C is placed in an ultrasonic device for ultrasonic oscillation treatment for 20 minutes, the ultrasonic power is controlled at 1000W, and the ultrasonic frequency is controlled at 15Hz, and a solution D is obtained; the solution D is placed in a centrifuge and rotated at 7000r / min for 5 minutes to separate a modified polyaluminium chloride solution; the modified polyaluminium chloride solution is placed in a dryer and dried at 50°C for 20 hours to obtain a modified polyaluminium chloride.

[0093] Next, add 20 mg / m 3 The modified polyacrylamide was subjected to coagulation reaction and stayed for 45 minutes; the modified polyacrylamide was prepared by the following method: 1.5 parts of zinc oxide, 6 parts of sodium hydroxide, 13 parts of urea, and 70 parts of pure water were mixed and stirred for 1 minute, and then placed in an incubator, and a solvent was obtained at a temperature of -10°C and a temperature of 20 minutes. 7 parts of polyacrylamide and 2 parts of kapok fiber were taken by mass, and the mixture was added to 18 parts of the solvent, stirred for 2 minutes, and a solution E was obtained; the solution E was placed in an ultrasonic device for ultrasonic oscillation treatment for 20 minutes, the ultrasonic power was controlled at 1000W, and the ultrasonic frequency was controlled at 15Hz, and a solution F was obtained; the solution F was placed in a centrifuge and rotated at 7000r / min for 5 minutes to obtain a modified polyacrylamide solution; the modified polyacrylamide solution was placed in a dryer and dried at 50°C for 18 hours to obtain a modified polyacrylamide.

[0094] Next, it is discharged into the secondary inclined tube sedimentation tank and stays for 40 minutes.

[0095] Next, it is discharged into the clean water tank and stays for 1.0 hour; if it passes the test, it will flow into the factory water system through the pipeline for continued use, and if it fails the test, it will flow into the accident emergency tank; the nickel-containing sludge formed after the secondary inclined tube sedimentation is discharged into the above-mentioned sludge tank and treated according to the above-mentioned sludge treatment steps.

[0096] The above-mentioned regulating tank, pH adjustment tank, primary oxidation tank, primary coagulation reaction tank, primary inclined tube sedimentation tank, sludge tank, secondary oxidation tank, secondary coagulation reaction tank, secondary inclined tube sedimentation tank, clear water tank and accident emergency tank are reinforced steel structures with an anti-corrosion layer inside, which is spliced ​​from anti-corrosion plates.

[0097] A stirrer is provided between the primary coagulation reaction tank and the secondary coagulation reaction tank. The stirrer has a power of 500W and a stirring speed of 50r / min.

[0098] Example 5

[0099] A method for treating nickel-containing wastewater specifically comprises the following steps:

[0100] The factory's nickel-containing wastewater is discharged into the regulating pond for water quality and quantity balance and stays there for 11 hours.

[0101] Next, it is discharged into the pH adjustment tank, calcium hydroxide is added to adjust the pH to 9, and the water is retained for 80 minutes.

[0102] Next, it was discharged into the primary oxidation tank and 60g / m 3 Calcium oxide undergoes oxidation reaction and stays for 3.0 hours.

[0103] Next, it was discharged into the primary coagulation reaction tank and 45g / m 3 The silica xerogel was subjected to coagulation reaction and stayed for 150 minutes.

[0104] Next, it is discharged into the primary inclined tube sedimentation tank and stays there for 70 minutes.

[0105] Next, it is discharged into the sludge pool, and a plate and frame filter press is set up. The nickel sludge after filtration is transported to a designated agency for recycling. The filtrate from the filtration is discharged into the clear water pool if it passes the test, and discharged into the secondary oxidation pool for further treatment if it fails the test.

[0106] Next, discharge into the secondary oxidation tank and add 600ml / m 3 The hydrogen peroxide undergoes oxidation reaction and stays for 2.0 hours.

[0107] Next, it was discharged into the secondary coagulation reaction tank and 300 mg / m 3 The modified polyaluminium chloride is subjected to a coagulation reaction and stays for 60 minutes; the modified polyaluminium chloride is prepared by the following method: 2.5 parts of zinc oxide, 8 parts of sodium hydroxide, 14 parts of urea, and 80 parts of pure water are mixed and stirred for 3 minutes, and then placed in an incubator, and a solvent is obtained at a temperature of -15°C and a temperature of 25 minutes. 10 parts of polyaluminium chloride and 4 parts of kapok fiber are taken by mass, and the mixture is added to 24 parts of the solvent, stirred for 5 minutes, and a solution C is obtained; the solution C is placed in an ultrasonic device for ultrasonic oscillation treatment for 30 minutes, the ultrasonic power is controlled at 1500W, and the ultrasonic frequency is controlled at 20Hz, to obtain a solution D; the solution D is placed in a centrifuge and rotated at 9000r / min for 10 minutes to separate the modified polyaluminium chloride solution; the modified polyaluminium chloride solution is placed in a dryer and dried at 60°C for 24 hours to obtain a modified polyaluminium chloride.

[0108] Next, add 40 mg / m 3 The modified polyacrylamide was subjected to coagulation reaction and stayed for 50 minutes; the modified polyacrylamide was prepared by the following method: 2.5 parts of zinc oxide, 8 parts of sodium hydroxide, 14 parts of urea, and 80 parts of pure water were mixed and stirred for 3 minutes, and then placed in an incubator, and a solvent was obtained at an insulation temperature of -15°C and an insulation temperature of 25 minutes. 9 parts of polyacrylamide and 3 parts of kapok fiber were taken by mass, and the mixture was added to 26 parts of the solvent and stirred for 5 minutes to obtain solution E; solution E was placed in an ultrasonic device for ultrasonic oscillation treatment for 30 minutes, with the ultrasonic power controlled at 1500W and the ultrasonic frequency controlled at 20Hz to obtain solution F; solution F was placed in a centrifuge and rotated at 9000r / min for 10 minutes to obtain a modified polyacrylamide solution; the modified polyacrylamide solution was placed in a dryer and dried at 55°C for 20 hours to obtain a modified polyacrylamide.

[0109] Next, it is discharged into the secondary inclined tube sedimentation tank and stays for 60 minutes.

[0110] Next, it is discharged into the clean water tank and stays for 2.0 hours; if it passes the test, it will flow into the factory water system through the pipeline for continued use, and if it fails the test, it will flow into the accident emergency tank; the nickel-containing sludge formed after the secondary inclined tube sedimentation is discharged into the above-mentioned sludge tank and treated according to the above-mentioned sludge treatment steps.

[0111] The above-mentioned regulating tank, pH adjustment tank, primary oxidation tank, primary coagulation reaction tank, primary inclined tube sedimentation tank, sludge tank, secondary oxidation tank, secondary coagulation reaction tank, secondary inclined tube sedimentation tank, clear water tank and accident emergency tank are reinforced steel structures with an anti-corrosion layer inside, which is spliced ​​from anti-corrosion plates.

[0112] A stirrer is provided between the primary coagulation reaction tank and the secondary coagulation reaction tank. The stirrer has a power of 1000W and a stirring speed of 70r / min.

[0113] The silicon dioxide xerogels in the above-mentioned Examples 4 and 5 are prepared by the following steps:

[0114] S21: piperidine and aqueous ammonia: piperidine with a concentration of 10 wt % and aqueous ammonia with a concentration of 20 wt % were mixed, and stirred for 3 min, with a volume ratio of piperidine to aqueous ammonia being 1.2:1.5, to obtain solution A for standby use;

[0115] S22: dissolving tetraethyl orthosilicate: adding tetraethyl orthosilicate into solution A, stirring for 20 minutes, and stopping stirring when the solution turns milky white, to obtain a silica gel solution; the mass volume ratio of tetraethyl orthosilicate to solution A is 1.2:3;

[0116] S23: Aging and drying: The silica gel solution was aged at room temperature for 1.2 hours, then placed in an aging box at 85°C for further aging for 4.5 hours, taken out and left in the air at room temperature for 15 hours, then placed in a dryer and dried at 85°C for 4.5 hours to obtain a silica dry gel.

[0117] Determination of Nickel

[0118] According to the method and requirements of GB / T 11982-1989 "Determination of Nickel in Water Quality by Flame Atomic Absorption Spectrophotometry", the nickel concentration in the wastewater treated by Examples 1-5 was determined respectively. The nickel concentration was calculated according to the following formula:

[0119]

[0120] Where c represents the nickel concentration in the sample in mg / L, m represents the nickel content in the sample in μg, and v represents the volume of the sample in ml.

[0121] The measurement results are shown in Table 1 below:

[0122] Table 1

[0123]

[0124] From the above results, it can be seen that the treatment method of the present invention can effectively remove the nickel content in the wastewater, and the nickel content in the wastewater after treatment meets the requirements of the emission limit value of ≤0.1 mg / L in the Pearl River Delta region in Table 2 of the Guangdong Provincial Local Standard DB441957-2015 "Electroplating Water Pollutant Emission Standard". Example 3 of the present invention method has the best effect.

[0125] According to the treatment results of Example 3, two groups of comparison ratios were set up for verification.

[0126] Comparative Example 1

[0127] The difference between Comparative Example 1 and Example 3 is that Comparative Example 1 has only one level of coagulation treatment process, that is, only the secondary coagulation treatment process in this unit.

[0128] Comparative Example 2

[0129] Comparative Example 2 is compared with Example 3, except that an equal mass of commercially available silica gel is used instead of the silica xerogel prepared by the method of the present invention.

[0130] According to the above-mentioned nickel content determination method and formula, the nickel concentration in the wastewater treated according to Comparative Example 1-2 was determined and compared with Example 3. The determination results are shown in Table 2 below:

[0131] Table 2

[0132] Example 3 Comparative Example 1 Comparative Example 2 Nickel concentration mg / L 0.05 0.21 0.12

[0133] Compared with Comparative Example 1, in the first stage coagulation treatment, larger suspended and colloidal nickel-containing pollutants are removed, while in the second stage coagulation treatment, smaller nickel-containing pollutants can be removed more effectively. Therefore, this two-stage treatment method can more comprehensively remove various pollutants in nickel-containing wastewater. Compared with Comparative Example 2, in the present invention, the reaction conditions of piperidine and ammonia water are mild, and the prepared silica xerogel has a high specific surface area, a good pore structure and a high stability. These properties make the silica xerogel have a high adsorption capacity and a filtering effect in the treatment of nickel-containing wastewater, and can effectively remove nickel ions in nickel-containing wastewater.

[0134] An additional set of comparative example 3 is set up to compare the sludge moisture content with implementation 3.

[0135] Comparative Example 3

[0136] Comparative Example 3 is compared with Example 3, except that equal masses of polyaluminium chloride and polyacrylamide are used to replace modified polyaluminium chloride and modified polyacrylamide, respectively.

[0137] Moisture content determination

[0138] Follow the steps below to determine the sludge moisture content:

[0139] 1. Take the nickel-containing sludge after secondary coagulation treatment of Example 3 and Comparative Example 3 respectively and spread it evenly in an aluminum box of known mass. Use an electronic balance to weigh the total mass of the aluminum box plus the sludge, which is recorded as m1.

[0140] 2. Then put the aluminum box into the oven for drying, the oven temperature is set to 105℃, and the drying time is 2 hours. Take out the dried aluminum box and put it in the dryer to cool. After cooling, weigh the total mass of the dried aluminum box and sludge with an electronic balance, recorded as m2.

[0141] The sludge moisture content is calculated according to the following formula:

[0142]

[0143] Where x is the moisture content of the sludge, m1 is the total mass of the sludge plus the aluminum box before drying, and m2 is the total mass of the sludge plus the aluminum box after drying. The measurement results are shown in Table 3 below:

[0144] Table 3

[0145] Example 3 Comparative Example 3 Sludge moisture content% 60 98

[0146] Compared with Comparative Example 3, Example 3 modifies polyaluminium chloride and polyacrylamide by introducing hydrophobic functional groups of kapok fibers into polyaluminium chloride and polyacrylamide to further improve their hydrophobicity, thereby reducing the moisture content in the sludge from 98% to 60%, thereby reducing the burden on subsequent processes.

[0147] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for treating nickel-containing wastewater, characterized in that: The following processes are set up: pretreatment, primary coagulation treatment, sludge treatment, secondary coagulation treatment, discharge treatment and accident treatment; specifically including the following steps: S1: Pretreatment: including regulating tank and pH adjustment tank. Alkaline agent is added into the pH adjustment tank to adjust the pH to 8-9; S2: primary coagulation treatment: including primary oxidation tank, primary coagulation reaction tank, primary inclined tube sedimentation tank; adding oxidant 1 to the primary oxidation tank for oxidation reaction, staying for 2.0-3.0h; then adding coagulant 1 to the primary coagulation reaction tank for coagulation reaction, staying for 140-150min; then discharging into the primary inclined tube sedimentation tank, staying for 50-70min; Sludge treatment: S3: Sludge treatment: The nickel-containing sludge formed after the first-level inclined tube sedimentation is discharged into the sludge pool; a plate and frame filter press is set up, and the nickel sludge after filtration is transported to a designated agency for recycling. The filtrate from the filtration is discharged into the clear water pool if it is qualified, and discharged into the secondary oxidation pool if it is unqualified for further treatment; S4: Secondary coagulation treatment: including secondary oxidation tank, secondary coagulation reaction tank, and secondary inclined tube sedimentation tank; the nickel-containing wastewater after primary coagulation treatment and sludge treatment is discharged into the secondary oxidation tank, and oxidant 2 is added to the secondary oxidation tank for oxidation reaction, and the reaction is retained for 1.5-2.0 hours; then coagulant 2 is added to the secondary coagulation reaction tank for coagulation reaction, and the reaction is retained for 50-60 minutes; then coagulant 3 is added for coagulation reaction, and the reaction is retained for 45-50 minutes; then the wastewater is discharged into the secondary inclined tube sedimentation tank, and the reaction is retained for 40-60 minutes; S5: Discharge treatment: The clear liquid after secondary coagulation treatment is discharged into the clear water tank; if it passes the test, it will flow into the plant water system through the pipeline for continued use, and if it fails the test, it will flow into the accident emergency tank; the nickel-containing sludge formed after the secondary inclined tube sedimentation is discharged into the sludge tank and the nickel-containing sludge is treated according to S3.

2. A method for treating nickel-containing wastewater as claimed in claim 1, characterized in that: The regulating tank, pH adjustment tank, primary oxidation tank, primary coagulation reaction tank, primary inclined tube sedimentation tank, sludge tank, secondary oxidation tank, secondary coagulation reaction tank, secondary inclined tube sedimentation tank and clear water tank are connected in sequence and are all reinforced structures with an anti-corrosion layer inside, which is made of anti-corrosion plates.

3. A method for treating nickel-containing wastewater as claimed in claim 1, characterized in that: A stirrer is provided between the primary coagulation reaction tank and the secondary coagulation reaction tank. The stirrer has a power of 500-1000W and a stirring speed of 50-70r / min.

4. A method for treating nickel-containing wastewater as claimed in claim 1, characterized in that: The alkaline agent in S1 is one of sodium hydroxide and calcium hydroxide.

5. A method for treating nickel-containing wastewater as claimed in claim 1, characterized in that: The oxidant 1 in S2 is calcium oxide, and the addition amount is 50-60g / m 3 .

6. A method for treating nickel-containing wastewater as claimed in claim 1, characterized in that: The coagulant 1 in S2 is silica xerogel, and the added amount is 35-45g / m 3 , the silicon dioxide xerogel is prepared by the following steps: S21: piperidine and aqueous ammonia: piperidine with a concentration of 1-10 wt % and aqueous ammonia with a concentration of 15-20 wt % are mixed, and stirred for 1-3 min, wherein the volume ratio of piperidine to aqueous ammonia is (1-1.2):(1-1.5), to obtain solution A for standby use; S22: dissolving tetraethyl orthosilicate: adding tetraethyl orthosilicate to solution A, stirring for 10-20 min, and stopping stirring when the solution turns milky white, to obtain a silica gel solution; the mass volume ratio of tetraethyl orthosilicate to solution A is (0.8-1.2):(2-3); S23: Aging and drying: Aging the silica gel solution at room temperature for 1-1.2 hours, then placing it in an aging box at 75-85°C for further aging for 3.5-4.5 hours, taking it out and leaving it in the air at room temperature for 13-15 hours, then placing it in a dryer at 75-85°C for 3.5-4.5 hours to obtain a silica xerogel.

7. A method for treating nickel-containing wastewater as claimed in claim 1, characterized in that: The oxidant 2 in S4 is hydrogen peroxide, and the amount added is 300-600ml / m 3 .

8. A method for treating nickel-containing wastewater as claimed in claim 1, characterized in that: The coagulant 2 in S4 is modified polyaluminium chloride, and the amount of modified polyaluminium chloride added is 100-300 mg / m 3 The modified polyaluminium chloride is prepared by the following method: 8-10 parts by mass of polyaluminium chloride and 2-4 parts of kapok fibre are added to 20-24 parts of a solvent and stirred for 2-5 minutes to obtain a solution C; the solution C is placed in an ultrasonic device for ultrasonic oscillation treatment for 20-30 minutes, the ultrasonic power is controlled at 1000-1500W, and the ultrasonic frequency is controlled at 15-20Hz to obtain a solution D; the solution D is placed in a centrifuge and rotated at 7000-9000r / min for 5-10 minutes to separate the modified polyaluminium chloride solution; The modified polyaluminium chloride solution is placed in a dryer and dried at 50-60°C for 20-24 hours to obtain modified polyaluminium chloride.

9. A method for treating nickel-containing wastewater as claimed in claim 1, characterized in that: The coagulant 3 in S4 is modified polyacrylamide, and the amount of modified polyacrylamide added is 20-40 mg / m 3 The modified polyacrylamide is prepared by the following method: 7-9 parts of polyacrylamide and 2-3 parts of kapok fiber are taken, the mixture is added to 18-26 parts of a solvent, and stirred for 2-5 minutes to obtain a solution E; the solution E is placed in an ultrasonic device for ultrasonic oscillation treatment for 20-30 minutes, the ultrasonic power is controlled at 1000-1500W, and the ultrasonic frequency is controlled at 15-20Hz to obtain a solution F; the solution F is placed in a centrifuge and rotated at 7000-9000r / min for 5-10 minutes to obtain a modified polyacrylamide solution; The modified polyacrylamide solution is placed in a dryer and dried at 50-55° C. for 18-20 hours to obtain modified polyacrylamide.

10. A method for treating nickel-containing wastewater as claimed in claim 8 or 9, characterized in that: The dissolving agent is prepared by mixing 1.5-2.5 parts of zinc oxide, 6-8 parts of sodium hydroxide, 13-14 parts of urea and 70-80 parts of pure water and stirring for 1-3 minutes, and then placed in an insulated box at an insulated temperature of -10°C to -15°C for 20-25 minutes to obtain the dissolving agent.

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