A method for resourceful treatment of nickel hydrazine nitrate production wastewater

Abstract

The present application relates to the technical field of resourceful treatment of nickel hydrazine nitrate production wastewater, and particularly relates to a resourceful treatment method of nickel hydrazine nitrate production wastewater. The present application mixes the wastewater mother liquor obtained by filtering the mother liquor of nickel hydrazine nitrate production and the washing wastewater of the first deionized water washing into mixed wastewater, recovers metal nickel by electrolytic deposition of pure nickel cathode after acid adjustment, further converts nitrate and oxidizes hydrazine hydrate by secondary electrolysis, removes residual nickel ions by flocculation after electrolysis, carries out biochemical treatment after phosphorus supplement, further removes nitrogen, and obtains reuse water which can be reused in production by fine treatment such as ion exchange resin, so as to realize resourceful recovery of nickel and purification of wastewater.

Description

Technical Field

[0001] This invention relates to the field of resource utilization treatment technology for nickel hydrazine nitrate production wastewater, specifically to a resource utilization treatment method for nickel hydrazine nitrate production wastewater. Background Technology

[0002] In the production of nickel hydrazine nitrate, an aqueous solution of nickel nitrate is used as the base liquid. After heating to a certain temperature, hydrazine hydrate is slowly added dropwise under stirring to initiate a chemical reaction, producing solid granular nickel hydrazine nitrate. The mother liquor after separating the nickel hydrazine nitrate contains unreacted nickel nitrate, hydrazine hydrate, and nickel hydrazine nitrate dissolved in the mother liquor. Under certain conditions, the nickel hydrazine nitrate mother liquor can precipitate the detonating agent nickel hydrazine nitrate. If directly discharged into the wastewater system, it will react chemically with other metal ions, potentially generating other explosive substances. Therefore, direct discharge of the nickel hydrazine nitrate mother liquor poses a safety hazard. In the factory's nickel hydrazine nitrate production process, there is a step to eliminate the explosion hazard of the mother liquor, known as the detonation step. This step typically requires the addition of chemical agents to destroy the explosive substances generated in the mother liquor. The granular product obtained after filtration following the reaction is usually washed with deionized water and anhydrous ethanol, a process that simultaneously generates washing wastewater.

[0003] In existing technologies, the production mother liquor and washing wastewater after detonation are typically discharged into the factory's wastewater treatment system and treated together with other wastewater from the factory until they meet the wastewater discharge standards before being discharged. Existing methods for treating mother liquor and washing wastewater require the addition of large amounts of chemical agents to the mother liquor, increasing the load on subsequent wastewater treatment systems. Chinese Patent CN115259462B discloses a method for treating pharmaceutical wastewater from NHN detonating explosives. This method involves connecting an alkaline feed tank to the detonation device and adding sodium hydroxide solution to the pharmaceutical wastewater within the detonation device. The sodium hydroxide solution not only forms nickel hydroxide precipitate to remove heavy metal ions from the wastewater but also serves as a detonation agent, eliminating the need for nitric acid during the detonation process. However, this method still requires the use of large amounts of chemical reagents in the detonation process and fails to effectively recover nickel from the production mother liquor, thus failing to achieve the goal of resource recovery of the production mother liquor.

[0004] Therefore, it is crucial to develop a treatment method for nickel hydrazine nitrate production wastewater to address the issues of nickel resource loss, the difficulty in degrading nitrate nitrogen and hydrazine hydrate, and the safety risks posed by hydrazine-containing systems. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a method for the combined treatment of nickel hydrazine nitrate wastewater through electrolysis, biochemical processes, and ion exchange, enabling wastewater reuse. By collecting the nickel hydrazine nitrate production mother liquor and graded washing wastewater, and subjecting them to triple treatment via electrolysis, biochemical processes, and ion exchange, the method achieves both nickel resource recovery and the purification of nitrogen and hydrazine pollutants.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for the resource-based treatment of wastewater from the production of nickel hydrazine nitrate, comprising the following steps:

[0008] S1, filter the mother liquor from the nickel hydrazine nitrate production process to obtain wastewater mother liquor and nickel hydrazine nitrate; the first washing liquid of washing the nickel hydrazine nitrate with deionized water is wastewater A; continue washing the nickel hydrazine nitrate with deionized water and collect the washing liquid to obtain wastewater B; wash the nickel hydrazine nitrate with anhydrous ethanol and collect the washing liquid to obtain wastewater C; mix the wastewater mother liquor and wastewater A to obtain mixed wastewater.

[0009] S2, the mixed wastewater is transported to a two-stage series industrial electrolyzer. The pH is adjusted in the first stage electrolyzer to obtain electrolyte A, which is then subjected to the first electrolysis. After the first electrolysis, the pH of the electrolyte is adjusted to obtain electrolyte B. Electrolyte B is then transported to the second stage electrolyzer for the second electrolysis. After the second electrolysis, the electrolyzed effluent is obtained.

[0010] S3, mix the electrolyzed water with wastewater B and wastewater C, adjust the pH to obtain wastewater D, flocculate, filter and collect the filtrate, add phosphorus supplement to the filtrate to obtain wastewater E, and after biological treatment of wastewater E, obtain biologically treated water.

[0011] S4, ion exchange resin method is used to treat biochemically treated water to obtain recycled water.

[0012] The wastewater from the nickel hydrazine nitrate production process is explosive. The nitrogen in the filtered wastewater mother liquor mainly exists in the form of hydrazine nitrogen and nitrate nitrogen, and may also contain small amounts of ammonium nitrogen produced from the partial decomposition of hydrazine or byside reactions. The core purpose of the first electrolysis is the electrochemical recovery of metallic nickel, while the purpose of the second electrolysis is to simultaneously convert nitrate and residual hydrazine using a catalytic electrode. During the first electrolysis, hydrazine hydrate is oxidized at the anode, causing hydrazine nitrogen to escape as nitrogen gas. During the second electrolysis, nitrate nitrogen is reduced at the cathode, ultimately generating ammonium ions or escaping as nitrogen gas. These ammonium ions can be removed by the hydrogen ion exchange resin in the subsequent S4 stage. In the biological treatment, denitrifying bacteria in the anaerobic biological stage use ethanol in wastewater E as an electron donor and carbon source to reduce nitrate in wastewater E to nitrogen gas, achieving deep nitrate removal. Aerobic bacteria in the aerobic biological stage degrade residual hydrazine hydrate and organic matter. The remaining ammonium ions are removed by the ion exchange resin.

[0013] The wastewater treated by this patent originates from the production process of nickel hydrazine nitrate. The wastewater may contain residual nickel hydrazine nitrate, free hydrazine, and nickel nitrate, which together constitute multiple safety risk factors. This invention mixes wastewater A with the wastewater mother liquor to form mixed wastewater, diluting both hydrazine and nickel hydrazine nitrate and reducing safety risks during the electrolysis process.

[0014] Furthermore, in S2, the cathode of the first-stage electrolyzer is a pure nickel plate, and the anode is a graphite electrode or a platinum-plated titanium electrode.

[0015] Furthermore, in step S2, the pH of the electrolyte A is 3.0 to 4.5.

[0016] Furthermore, in step S2, the electrolysis temperature of the first electrolysis is 40~60℃, and the current density is 200~300A / m. 2 The electrolysis time is 30~120min.

[0017] Furthermore, in S2, the pH of the electrolyte B is 7~9.

[0018] Furthermore, in S2, the cathode of the second-stage electrolyzer includes carbon cloth and a catalytic material supported on the carbon cloth, and the anode is a graphite electrode or a platinum-titanium plated electrode.

[0019] Furthermore, the catalytic material is cobalt and / or palladium.

[0020] Furthermore, the cathode of the second-stage electrolyzer is prepared by immersing carbon cloth in a solution containing 0.5 mol / L Co. 2+ or Pd 2+ In metal salt solutions, catalytic materials are loaded onto carbon cloth via impregnation-chemical reduction or electrodeposition methods, with a catalytic material loading of 0.5–2.0 mg / cm³. 2 .

[0021] Furthermore, in step S2, the electrolysis temperature of the second electrolysis is room temperature, and the current density of the second electrolysis is 80~150 A / m. 2 The electrolysis time is 30~120min.

[0022] Furthermore, in S3, the pH of the wastewater D is 7.5~8.5.

[0023] Further, in S3, the flocculation is achieved by adding polyaluminum chloride (PAC) and polyacrylamide (PAM) to wastewater D; the dosage of PAC is 100~300 mg / L, and the dosage of PAM is 1~5 mg / L.

[0024] Furthermore, in S3, the phosphorus supplement includes sodium phosphate, disodium hydrogen phosphate, or sodium dihydrogen phosphate.

[0025] Furthermore, in S3, the ratio of nitrogen to phosphorus in the wastewater E is 5:1.

[0026] Furthermore, in S3, the biochemical treatment includes an anaerobic biochemical stage, an aerobic biochemical stage, and a settling period, after which the supernatant is decanted; the anaerobic biochemical treatment lasts for 24 hours, the aerobic biochemical treatment lasts for 12 to 24 hours, and the settling period lasts for 30 to 60 minutes.

[0027] Furthermore, in S3, the biochemical treatment includes activated sludge treatment and / or biochemical microbial treatment.

[0028] Furthermore, the activated sludge treatment is a sequencing batch activated sludge process.

[0029] Furthermore, during the activated sludge treatment, anaerobic activated sludge is first inoculated into wastewater E for anaerobic biological treatment. The supernatant is then decanted, and aerobic activated sludge is inoculated into the supernatant for aerobic biological treatment. After treatment, the supernatant is decanted to obtain biologically treated water. The inoculation amount of the anaerobic activated sludge is 10-30% of the effective volume of the reactor, and the sludge concentration of the mixed liquor is 2000-4000 mg / L. The inoculation amount of the aerobic activated sludge is 10-30% of the effective volume of the reactor, and the sludge concentration of the mixed liquor is 2000-4000 mg / L.

[0030] Furthermore, the activated sludge is made from fresh activated sludge from an urban wastewater treatment plant, which is then gradually acclimatized before being put into operation.

[0031] Furthermore, during the biochemical bacterial treatment, wastewater treatment bacteria are inoculated into wastewater E. The bacteria include denitrifying bacteria and Bacillus. The inoculation amount of the wastewater treatment bacteria is 0.5~1g / L.

[0032] Furthermore, in step S4, the ion exchange resin method for treating biochemically treated water includes the following steps performed sequentially: coagulation and sedimentation, filtration, activated carbon adsorption, and precision filtration, wherein the filtrate from the precision filtration is passed sequentially through a hydrogen ion exchange resin column and a hydroxide ion exchange resin column.

[0033] Furthermore, the coagulation and sedimentation process uses polyaluminum chloride or polyferric sulfate as a coagulant, with a dosage of 50~100 mg / L.

[0034] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0035] This invention provides a resource-based treatment method for nickel hydrazine nitrate production wastewater. The method employs a combined electrolysis, biochemical, and ion exchange process to treat the wastewater, enabling its reuse. Two-stage electrolysis replaces traditional chemical reagents. The first electrolysis deposits metallic nickel on a pure nickel cathode, converting the nickel in the wastewater into a reusable metal resource and avoiding waste. Biochemical treatment further removes nitrate nitrogen and hydrazine hydrate, and finally, ion exchange resin further purifies the effluent, yielding recycled water that can be reused in production. Detailed Implementation

[0036] The technical solution of the present invention will be described in detail below through specific embodiments. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solution of the present invention, rather than limitations on the technical solution of the present invention.

[0037] In this embodiment of the invention, the anaerobic activated sludge used is fresh anaerobic activated sludge from an urban wastewater treatment plant as seed sludge, which is put into operation after gradual acclimatization. The gradual acclimatization is carried out by gradually increasing the proportion of wastewater E, and anaerobic operation is carried out for 2 cycles at each wastewater E proportion gradient. The acclimatization endpoint of the anaerobic activated sludge is: when the wastewater E reaches the design influent concentration, the nitrate nitrogen denitrification removal rate is ≥90% within 3 consecutive operating cycles, and the mixed liquor sludge concentration and sludge settling performance remain stable.

[0038] In this embodiment of the invention, the aerobic activated sludge used is fresh aerobic activated sludge from an urban wastewater treatment plant as seed sludge, which is put into operation after gradual acclimatization. The gradual acclimatization is carried out by gradually increasing the proportion of wastewater E, and aerobic operation is carried out for 2 cycles at each wastewater E proportion gradient. The acclimatization endpoint of the aerobic activated sludge is: when the wastewater E reaches the design influent concentration, the hydrazine hydrate removal rate is ≥95% within 3 consecutive operating cycles, and the mixed liquor sludge concentration and sludge settling performance remain stable.

[0039] Example 1

[0040] This embodiment provides a method for the resource-based treatment of wastewater from the production of nickel hydrazine nitrate, comprising the following steps:

[0041] S1, filter the mother liquor from the nickel hydrazine nitrate production process to obtain wastewater mother liquor and nickel hydrazine nitrate; wash the nickel hydrazine nitrate with three times the volume of deionized water, collect the first washing liquid from the deionized water washing process to obtain wastewater A; wash the nickel hydrazine nitrate with deionized water until the washing liquid is neutral, collect the washing liquid to obtain wastewater B; wash the nickel hydrazine nitrate with anhydrous ethanol until no Ni is present in the washing liquid. 2+ Collect the washing liquid to obtain wastewater C; mix the wastewater mother liquor and wastewater A to obtain mixed wastewater;

[0042] S2, the mixed wastewater is transported to a two-stage industrial electrolyzer connected in series. The cathode of the first-stage electrolyzer is a pure nickel plate, and the anode is a graphite electrode. The cathode of the second-stage electrolyzer consists of carbon cloth and cobalt loaded on the carbon cloth, with a cobalt loading of 2.0 mg / cm³. 2 The anode is a graphite electrode. In the first-stage electrolyzer, the pH of the mixed wastewater is adjusted to 3.5 to obtain electrolyte A. Electrolyte A undergoes its first electrolysis in the first-stage electrolyzer at a temperature of 50℃ and a current density of 250 A / m³. 2 The electrolysis time was 75 minutes. The electrolyte after the first electrolysis was adjusted to pH 8 to obtain electrolyte B. Electrolyte B was then transferred to the second-stage electrolyzer for a second electrolysis at room temperature. The current density of the second electrolysis was 110 A / m³. 2 The electrolysis time is 75 minutes, and the electrolyzed water is obtained after the second electrolysis.

[0043] S3. The electrolyzed water is mixed with wastewater B and wastewater C. The pH of the mixture is adjusted to 8 to obtain wastewater D. 200 mg / L PAC and 3 mg / L PAM are added to wastewater D for flocculation. The filtrate is collected by filtration. Disodium hydrogen phosphate is added to the filtrate, with the nitrogen-to-phosphorus ratio in the filtrate being 5:1, to obtain wastewater E. Wastewater E is transferred to an anaerobic bioreactor. Anaerobic activated sludge is inoculated at 20% of the effective volume of the reactor, with a mixed liquor sludge concentration of 3000 mg / L. After anaerobic operation for 24 hours, the supernatant is decanted and transferred to an aerobic bioreactor. Aerobic activated sludge is inoculated at 10% of the effective volume of the reactor, with a mixed liquor sludge concentration of 4000 mg / L. After aerobic operation for 18 hours, the supernatant is decanted after standing for 45 minutes to obtain biotreated water. The activated sludge is retained in the tank for reuse.

[0044] S4. Treat the biochemically treated water using ion exchange resin to obtain recycled water. The ion exchange resin treatment of the biochemically treated water includes the following steps in sequence: coagulation sedimentation, filtration, activated carbon adsorption and precision filtration. The filtrate from the precision filtration is passed sequentially through a hydrogen ion exchange resin column and a hydroxide ion exchange resin column. Polyaluminum chloride is used as a coagulant for coagulation sedimentation at a dosage of 75 mg / L.

[0045] Example 2

[0046] This embodiment provides a method for the resource-based treatment of wastewater from the production of nickel hydrazine nitrate, comprising the following steps:

[0047] S1, filter the mother liquor from the nickel hydrazine nitrate production process to obtain wastewater mother liquor and nickel hydrazine nitrate; wash the nickel hydrazine nitrate with four times the volume of deionized water, collect the first washing liquid from the deionized water wash, to obtain wastewater A; wash the nickel hydrazine nitrate with deionized water until the washing liquid is neutral, collect the washing liquid, to obtain wastewater B; wash the nickel hydrazine nitrate with anhydrous ethanol until no Ni is present in the washing liquid. 2+ Collect the washing liquid to obtain wastewater C; mix the wastewater mother liquor and wastewater A to obtain mixed wastewater;

[0048] S2, the mixed wastewater is transported to a two-stage industrial electrolyzer connected in series. The cathode of the first-stage electrolyzer is a pure nickel plate, and the anode is a platinum-plated titanium electrode. The cathode of the second-stage electrolyzer consists of carbon cloth and palladium loaded on the carbon cloth, with a palladium loading of 1.0 mg / cm³. 2 The anode is a platinum-plated titanium electrode. In the first-stage electrolyzer, the pH of the mixed wastewater is adjusted to 3.0 to obtain electrolyte A. Electrolyte A undergoes its first electrolysis in the first-stage electrolyzer at a temperature of 60℃ and a current density of 300 A / m³. 2 The electrolysis time was 30 minutes. The electrolyte after the first electrolysis was adjusted to pH 9 using a 15 wt.% sodium hydroxide solution to obtain electrolyte B. Electrolyte B was then transferred to the second-stage electrolyzer for a second electrolysis at room temperature. The current density for the second electrolysis was 150 A / m³. 2 The electrolysis time is 30 minutes, and the electrolyzed water is obtained after the second electrolysis.

[0049] S3. The electrolyzed water is mixed with wastewater B and wastewater C. The pH of the mixture is adjusted to 8.5 to obtain wastewater D. 300 mg / L PAC and 5 mg / L PAM are added to wastewater D for flocculation. The filtrate is collected by filtration. Sodium dihydrogen phosphate is added to the filtrate, with the nitrogen-to-phosphorus ratio in the filtrate being 5:1, to obtain wastewater E. Wastewater E is transferred to an anaerobic bioreactor. Anaerobic activated sludge is inoculated at 30% of the effective volume of the reactor, with a mixed liquor sludge concentration of 2000 mg / L. After anaerobic operation for 24 hours, the supernatant is decanted and transferred to an aerobic bioreactor. Aerobic activated sludge is inoculated at 30% of the effective volume of the reactor, with a mixed liquor sludge concentration of 2000 mg / L. After aerobic operation for 24 hours, the supernatant is decanted after standing for 60 minutes to obtain biotreated water. The activated sludge is retained in the tank for reuse.

[0050] S4. Treat the biochemically treated water using ion exchange resin to obtain recycled water. The ion exchange resin treatment of the biochemically treated water includes the following steps in sequence: coagulation sedimentation, filtration, activated carbon adsorption and precision filtration. The filtrate from the precision filtration is passed sequentially through a hydrogen ion exchange resin column and a hydroxide ion exchange resin column. Polyferric sulfate is used as a coagulant for coagulation sedimentation at a dosage of 100 mg / L.

[0051] Example 3

[0052] This embodiment provides a method for the resource-based treatment of wastewater from the production of nickel hydrazine nitrate, comprising the following steps:

[0053] S1, filter the mother liquor from the nickel hydrazine nitrate production process to obtain wastewater mother liquor and nickel hydrazine nitrate; wash the nickel hydrazine nitrate with twice the volume of deionized water, collect the first washing liquid from the deionized water wash, to obtain wastewater A; wash the nickel hydrazine nitrate with deionized water until the washing liquid is neutral, collect the washing liquid, to obtain wastewater B; wash the nickel hydrazine nitrate with anhydrous ethanol until no Ni is present in the washing liquid. 2+ Collect the washing liquid to obtain wastewater C; mix the wastewater mother liquor and wastewater A to obtain mixed wastewater;

[0054] S2, the mixed wastewater is transported to a two-stage industrial electrolyzer connected in series. The cathode of the first-stage electrolyzer is a pure nickel plate, and the anode is a platinum-plated titanium electrode. The cathode of the second-stage electrolyzer consists of carbon cloth and palladium and cobalt loaded on the carbon cloth, with a combined cobalt and palladium loading of 0.5 mg / cm³. 2 The anode is a platinum-plated titanium electrode. In the first-stage electrolyzer, the pH of the mixed wastewater is adjusted to 4.5 to obtain electrolyte A. Electrolyte A undergoes its first electrolysis in the first-stage electrolyzer at a temperature of 40℃ and a current density of 200 A / m³. 2 The electrolysis time was 120 minutes. The electrolyte after the first electrolysis was adjusted to pH 7 to obtain electrolyte B. Electrolyte B was then transferred to the second-stage electrolyzer for a second electrolysis at room temperature. The current density of the second electrolysis was 80 A / m³. 2 The electrolysis time was 120 minutes, and the electrolyzed water was obtained after the second electrolysis.

[0055] S3. The electrolyzed water is mixed with wastewater B and wastewater C. The pH of the mixture is adjusted to 7.5 to obtain wastewater D. 100 mg / L PAC and 1 mg / L PAM are added to wastewater D for flocculation. The filtrate is collected by filtration. Sodium phosphate is added to the filtrate, with the nitrogen-to-phosphorus ratio in the filtrate being 5:1, to obtain wastewater E. Wastewater E is transferred to a biological reactor, and then to an anaerobic biological reactor. Anaerobic activated sludge is inoculated at 10% of the effective volume of the reactor, with a mixed liquor sludge concentration of 4000 mg / L. After anaerobic operation for 24 hours, the supernatant is decanted and transferred to an aerobic biological reactor. Aerobic activated sludge is inoculated at 20% of the effective volume of the reactor, with a mixed liquor sludge concentration of 3000 mg / L. After aerobic operation for 12 hours, the supernatant is decanted after standing for 30 minutes to obtain biotreated water. The activated sludge is retained in the tank for reuse.

[0056] S4. Treat the biochemically treated water using ion exchange resin to obtain recycled water. The ion exchange resin treatment of the biochemically treated water includes the following steps performed in sequence: coagulation and sedimentation, filtration, activated carbon adsorption and precision filtration. The filtrate from the precision filtration is passed sequentially through a hydrogen ion exchange resin column and a hydroxide ion exchange resin column. Polyaluminum chloride is used as a coagulant for coagulation and sedimentation at a dosage of 50 mg / L.

[0057] Comparative Example 1

[0058] A method for the resource-based treatment of wastewater from the production of nickel hydrazine nitrate differs from Example 1 in that S2 is replaced by the commonly used dilute nitric acid ignition and explosion process in the prior art, while other operating steps and process parameters are exactly the same as in Example 1.

[0059] Comparative Example 2

[0060] A method for the resource-based treatment of wastewater from the production of nickel hydrazine nitrate differs from Example 1 in that the biochemical treatment process S3 is omitted, and the filtrate collected after flocculation and filtration directly enters S4. Other operating steps and process parameters are exactly the same as in Example 1.

[0061] Comparative Example 3

[0062] A method for the resource-based treatment of wastewater from the production of nickel hydrazine nitrate differs from Example 1 in that step S4 is omitted, and the biochemically treated water is used as recycled water. The other operating steps and process parameters are exactly the same as in Example 1.

[0063] The processing methods of Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing, and the specific process is as follows:

[0064] Nickel recovery rate: Electrolyte A from each example and comparative example (comparative example 1 used mixed wastewater before detonation) was taken, and the concentration C1 of nickel ions was measured. At the same time, the volume V1 of electrolyte A delivered to the first-stage electrolyzer was recorded. The total amount M1 of nickel ions in electrolyte A was calculated using the following formula:

[0065]

[0066] M1 represents the theoretical extraction amount of nickel ions from electrolyte A.

[0067] After the first electrolysis, the cathode was removed from the electrolyzer, and the residual electrolyte was washed away with deionized water. The nickel deposited on the cathode was collected, washed with deionized water until the pH of the washing solution was 6.5, and vacuum dried at 60°C to constant weight. The residue was then weighed to obtain the actual nickel extraction amount M2. The nickel recovery rate η was calculated using the following formula:

[0068] .

[0069] Reclaimed water testing: Take the reclaimed water prepared in each example and comparative example S4, and determine its pH value, chemical oxygen demand (CODcr), five-day biochemical oxygen demand (BOD5), suspended solids content (SS), hydrazine content, ammonia nitrogen content, total nitrogen content (TN), and total nickel content.

[0070] Table 1 Performance test results of the examples and comparative examples

[0071]

[0072] As shown in Table 1, the nickel recovery rates of Examples 1 to 3 are all higher than 92%, and the various indicators of the prepared recycled water are maintained at a low level, which can be reused in the nickel hydrazine nitrate production process.

[0073] The effluent parameters of Comparative Example 1 are most similar to those of Example 1, with only an increase in total nickel and total nitrogen content. In Comparative Example 1, the mixed wastewater was subjected to ignition using dilute nitric acid, which oxidized and decomposed hydrazine hydrate to eliminate the explosiveness. This process did not involve electrochemical deposition, and nickel remained in the solution in ionic form. By adjusting the pH of the wastewater after ignition, nickel ions were removed as nickel hydroxide precipitate. However, the removal rate of nickel by this chemical precipitation method was not as high as that of electrolytic deposition, so a small amount of nickel residue remained at the effluent outlet. The increase in total nitrogen content was due to the introduction of additional nitrate ions into the system by the use of dilute nitric acid for ignition, which increased the denitrification load.

[0074] The effluent indicators of Comparative Example 2 showed a significant increase in CODcr and total nitrogen content. This may be because Comparative Example 2 omitted the biological treatment process, and the high concentration of ethanol in the wastewater was not consumed by the biological process or removed by the ion exchange process, but directly penetrated to the effluent. Since ethanol has an extremely high COD equivalent, it increased the overall CODcr and BOD5 values ​​of the system. The nickel ion concentration detected in the effluent of Comparative Example 2 was higher than that of the Comparative Example and Comparative Example 1. This may be because after omitting the biological treatment in Comparative Example 2, the high concentration of ethanol and other organic matter in the wastewater may form complexes with nickel ions, reducing the removal efficiency of nickel by flocculation and ion exchange, resulting in a slightly higher nickel ion concentration in the effluent than in the Example.

[0075] The pH value, ammonia nitrogen content, total nitrogen content, and total nickel content of the effluent in Comparative Example 3 were all higher than those in Example 1. This may be because Comparative Example 3 used the biochemically treated water directly as recycled water. Although the biochemical process removed organic matter and ammonia nitrogen, it could not remove inorganic salts, resulting in an increase in various ion indicators in Comparative Example 3. The total nickel content of Comparative Example 3 was much higher than that in Example 1, Comparative Example 2, and Comparative Example 3. This is because Comparative Example 3 lacked the ion exchange step S4. The flocculation process in S3 alone could not completely remove nickel from the system, and nitrate and ammonium ions were not exchanged and removed.

[0076] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for the resource-based treatment of wastewater from the production of nickel hydrazine nitrate, characterized in that, Includes the following steps: S1, filter the mother liquor from the nickel hydrazine nitrate production process to obtain wastewater mother liquor and nickel hydrazine nitrate; the first washing liquid of washing the nickel hydrazine nitrate with deionized water is wastewater A; continue washing the nickel hydrazine nitrate with deionized water and collect the washing liquid to obtain wastewater B; wash the nickel hydrazine nitrate with anhydrous ethanol and collect the washing liquid to obtain wastewater C; mix the wastewater mother liquor and wastewater A to obtain mixed wastewater. S2, the mixed wastewater is transported to a two-stage series industrial electrolyzer. The pH is adjusted in the first stage electrolyzer to obtain electrolyte A, which is then subjected to the first electrolysis. After the first electrolysis, the pH of the electrolyte is adjusted to obtain electrolyte B. Electrolyte B is then transported to the second stage electrolyzer for the second electrolysis. After the second electrolysis, the electrolyzed effluent is obtained. S3, mix the electrolyzed water with wastewater B and wastewater C, adjust the pH to obtain wastewater D, flocculate, filter and collect the filtrate, add phosphorus supplement to the filtrate to obtain wastewater E, and after biological treatment of wastewater E, obtain biologically treated water. S4, ion exchange resin method is used to treat biochemically treated water to obtain recycled water.

2. The method for resource-based treatment of hydrazine nickel nitrate production wastewater according to claim 1, characterized in that, In S2, the cathode of the first-stage electrolyzer is a pure nickel plate, and the anode is a graphite electrode or a platinum-plated titanium electrode.

3. The method for resource-based treatment of hydrazine nickel nitrate production wastewater according to claim 1, characterized in that, In step S2, the pH of electrolyte A is 3.0~4.5; the electrolysis temperature of the first electrolysis is 40~60℃, and the current density is 200~300A / m³. 2 The electrolysis time is 30~120min.

4. The method for resource-based treatment of hydrazine nickel nitrate production wastewater according to claim 1, characterized in that, In step S2, the pH of the electrolyte B is 7-9; the electrolysis temperature of the second electrolysis is room temperature, and the current density of the second electrolysis is 80-150 A / m. 2 The electrolysis time is 30~120min.

5. The method for resource-based treatment of hydrazine nickel nitrate production wastewater according to claim 1, characterized in that, In S2, the cathode of the second-stage electrolyzer includes carbon cloth and catalytic material supported on the carbon cloth, and the anode is a graphite electrode or a platinum-titanium plated electrode.

6. The method for resource-based treatment of hydrazine nickel nitrate production wastewater according to claim 5, characterized in that, The catalytic material is cobalt and / or palladium.

7. The method for resource-based treatment of hydrazine nickel nitrate production wastewater according to claim 1, characterized in that, In S3, the pH of the wastewater D is 7.5~8.

5.

8. The method for resource-based treatment of hydrazine nickel nitrate production wastewater according to claim 1, characterized in that, In S3, the ratio of nitrogen to phosphorus in the wastewater E is 5:

1.

9. The method for resource-based treatment of hydrazine nickel nitrate production wastewater according to claim 1, characterized in that, In step S3, the biochemical treatment includes an anaerobic biochemical stage, an aerobic biochemical stage, and a settling period, after which the supernatant is decanted; the anaerobic biochemical treatment lasts for 24 hours, and the aerobic biochemical treatment lasts for 12 to 24 hours.

10. A method for resource-based treatment of hydrazine nickel nitrate production wastewater according to claim 1, characterized in that, In step S4, the ion exchange resin method for treating biochemically treated water includes the following steps performed in sequence: coagulation and sedimentation, filtration, activated carbon adsorption, and precision filtration. The filtrate from the precision filtration is passed sequentially through a hydrogen ion exchange resin column and a hydroxide ion exchange resin column.

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