CN111018197A - Method for treating alkaline zinc-nickel alloy electroplating and passivation mixed wastewater - Google Patents
Method for treating alkaline zinc-nickel alloy electroplating and passivation mixed wastewater Download PDFInfo
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
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- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/5236—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
- C02F1/5245—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents using basic salts, e.g. of aluminium and iron
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- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
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- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
- C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
- C02F1/56—Macromolecular compounds
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- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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- C02F2101/00—Nature of the contaminant
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- C02F2101/22—Chromium or chromium compounds, e.g. chromates
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- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/16—Nature of the water, waste water, sewage or sludge to be treated from metallurgical processes, i.e. from the production, refining or treatment of metals, e.g. galvanic wastes
Abstract
The invention provides a method for treating alkaline zinc-nickel alloy electroplating and passivation mixed wastewater, which comprises the steps of adding acid into the wastewater to adjust the pH value to 4-6, adding ferrous chloride, then adjusting the pH value to 10-12 by using lime emulsion, precipitating a carboxylic acid coordination agent by using the synergistic action of ferrous ions and calcium ions, reducing hexavalent chromium into trivalent chromium by the ferrous ions, generating hydroxide precipitate by part of zinc ions and the trivalent chromium ions, and filtering and separating the precipitate. Adding acid to adjust the pH value of the wastewater to 4.5-5.5, adding sodium dimethyldithiocarbamate or sodium diethyldithiocarbamate to precipitate nickel ions and zinc ions, and filtering and separating precipitates. And adding sodium hydroxide solution to adjust the pH value to 6-8, and reducing the COD of the wastewater by a biochemical method. The treatment result meets the requirements of the discharge standard of the electroplating pollutants in China, and has better market prospect.
Description
Technical Field
The invention belongs to the technical field of industrial wastewater treatment, and particularly relates to a method for treating alkaline zinc-nickel alloy electroplating and passivation mixed wastewater.
Background
The alkaline zinc-nickel alloy electroplating wastewater contains aliphatic polyamine complexing agent, such as diethylenetriamine, which has strong oxidation resistance and brings great difficulty to the treatment of the electroplating wastewater. Alkaline zinc-nickel alloy electroplating wastewater also contains a hydroxylamine complexing agent and an amino group-containing carboxylic acid complexing agent formed by oxidation of the hydroxylamine complexing agent, and the influence of these complexing agents on the wastewater treatment results has not been studied in the industry.
The Chinese patent of invention with the publication number of CN 104961273B discloses a technical proposal that: hydrogen peroxide is used for oxidizing a complexing agent, sodium dimethyldithiocarbamate is used for precipitating zinc ions and nickel ions under the condition that the pH is = 4.5-5.5, and the content of the nickel ions in the treated discharged wastewater meets the requirements of table 2 of GB21900-2008 'discharge Standard of electroplating pollutants'.
The Chinese patent of invention with application publication number "CN 107857389A" method for treating alkaline zinc-nickel alloy electroplating wastewater "discloses a technical scheme: and precipitating zinc ions and nickel ions by using sodium diethyldithiocarbamate under the condition that the pH is = 4.5-5.5, wherein when the concentration of zinc and nickel in the wastewater is less than or equal to 1% of the concentration of zinc and nickel in the plating solution, the content of nickel in the discharged wastewater after treatment meets the requirements of table 3 of GB21900-2008 'discharge Standard of electroplating pollutants'. However, tests show that the treatment method can also achieve the result on the wastewater generated by the just-opened alkaline zinc-nickel alloy plating tank, and for the alkaline zinc-nickel alloy plating tank used for a long time, hydroxylamine is oxidized into an amino-containing carboxylic acid coordination agent with stronger coordination capacity, so that the wastewater treatment result does not meet the requirements of GB 21900-. In many electroplating plants, the alkaline zinc-nickel alloy electroplating wastewater and the passivation wastewater are mixed together and discharged into a wastewater regulating reservoir, and the method is not suitable for treating the mixed wastewater, and the mixed wastewater is difficult to treat.
Disclosure of Invention
Based on the above, there is a need for a new method for treating alkaline zinc-nickel alloy electroplating and passivating mixed wastewater, so that zinc, nickel, chromium, cobalt, complexing agent and additive in the treated alkaline zinc-nickel alloy electroplating and passivating mixed wastewater can be effectively treated.
In order to achieve the purpose, the invention provides the following technical scheme:
the treatment method of the alkaline zinc-nickel alloy electroplating and passivating mixed wastewater comprises the following steps:
(1) under mechanical stirring, adding diluted hydrochloric acid into the mixed wastewater of the alkaline zinc-nickel alloy electroplating and passivation to adjust the pH value to 4-6, and adding a ferrous chloride solution;
(2) under mechanical stirring, adding lime emulsion into the wastewater treated in the step (1) to adjust the pH value to 10-12, and generating precipitates from a carboxylic acid coordination agent and part of heavy metal ions in the wastewater;
(3) adding a flocculating agent into the wastewater treated in the step (2) to enable precipitates to aggregate into large particles and then settle;
(4) filtering, and removing the precipitate treated in the step (3);
(5) under mechanical stirring, adding acid to adjust the pH value of the wastewater treated in the step (4) to 4.5-5.5, adding a chelating agent, and generating a precipitate by heavy metal ions;
(6) adding a flocculating agent into the wastewater treated in the step (5) to enable precipitates to aggregate into large particles and then settle;
(7) filtering, and removing the precipitate treated in the step (6);
(8) and (3) adding an alkali solution into the wastewater treated in the step (7) under mechanical stirring to adjust the pH to 6-8, and reducing COD by a biochemical method.
In some embodiments, the ferrous chloride solution in the step (1) contains ferrous chloride tetrahydrate with the mass concentration of (150-250) g/L; the volume ratio of the added ferrous chloride solution to the alkaline zinc-nickel alloy electroplating and passivating mixed wastewater is (0.3-2): 100.
In some embodiments, the mass concentration of calcium oxide in the lime emulsion in the step (2) is (50-100) g/L.
In some embodiments, the chelating agent in step (5) is a sodium dimethyldithiocarbamate solution, and the mass concentration of the sodium dimethyldithiocarbamate solution is (80-120) g/L.
In some embodiments, the volume ratio of the sodium dimethyldithiocarbamate solution added in the step (5) to the wastewater to be treated is (0.5-5): 100.
In some embodiments, the chelating agent in step (5) is a sodium diethyldithiocarbamate trihydrate solution, and the mass concentration of the sodium diethyldithiocarbamate trihydrate solution is (80-120) g/L.
In some embodiments, the volume ratio of the sodium diethyldithiocarbamate trihydrate solution added in the step (5) to the wastewater to be treated is (0.8-8): 100.
In some embodiments, the flocculating agent in the step (3) and the step (6) is a PAM (polyacrylamide) aqueous solution with the mass concentration of 3-8 g/L.
In some embodiments, dilute hydrochloric acid is used for adjusting the pH in the steps (1) and (5), and the dilute hydrochloric acid is 5-10% of hydrochloric acid in mass fraction; the alkali solution in the step (8) is a sodium hydroxide solution, and the mass concentration of the sodium hydroxide solution is (20-80) g/L.
In some of these embodiments, the biochemical process described in step (8) employs current biochemical degradation methods.
The mixed waste water of alkaline zinc-nickel alloy electroplating and passivation comprises alkaline zinc-nickel alloy electroplating rinsing water and passivation rinsing water, wherein the waste water contains zinc, nickel, trivalent chromium, hexavalent chromium, cobalt, aliphatic polyamine complexing agent, hydroxylamine complexing agent, carboxylic acid complexing agent and electroplating additive components.
In the pH range of 10-12, the synergistic effect of ferrous ions and calcium ions is utilized to precipitate and remove the carboxylic acid coordination agent in the wastewater, and the ferrous ions can reduce hexavalent chromium into trivalent chromium. The aliphatic polyamine has strong coordination capacity to nickel ions, cobalt ions and zinc ions and has no coordination effect on trivalent lattice ions. And removing the carboxylic acid coordination agent under the condition that the pH value is 10-12, and generating chromium hydroxide precipitate by trivalent lattice ions.
Under the condition that the pH value is 4.5-5.5, the sodium dimethyldithiocarbamate or sodium diethyldithiocarbamate can be precipitated to remove zinc ions, nickel ions and cobalt ions, and residual trivalent chromium ions can be further precipitated.
The aliphatic polyamine complexing agent in the alkaline zinc-nickel alloy electroplating wastewater has strong oxidation resistance, is basically ineffective by oxidation, and needs to be treated by a biochemical degradation method to reduce the COD (chemical oxygen demand) of the wastewater.
The electroplating wastewater treatment comprises two modes of mechanical stirring and air stirring, and the invention adopts mechanical stirring because: the mechanical stirring can prevent ferrous ions from being oxidized by air and losing the functions.
Based on the technical scheme, the invention has the following beneficial effects:
1. by utilizing the synergistic effect of ferrous ions and calcium ions, the carboxylic acid coordination agent containing amino in the alkaline zinc-nickel alloy electroplating wastewater is precipitated and the carboxylic acid coordination agent in the precipitation passivation mixed wastewater is precipitated, and meanwhile, trivalent lattice ions and partial zinc ions generate hydroxide precipitates, so that the treatment cost is low, and the technical defect that the traditional oxidation method cannot effectively destroy the carboxylic acid coordination agents such as citric acid is overcome.
2. And precipitating zinc ions, nickel ions, cobalt ions and residual trivalent chromium ions by using sodium dimethyldithiocarbamate or sodium diethyldithiocarbamate, so that the metal ions can be completely precipitated.
3. The treatment result of the treatment method of the alkaline zinc-nickel alloy electroplating and passivating mixed wastewater can meet the requirements of table 3 of GB21900-2008 'electroplating pollutant discharge standard'.
Detailed Description
In order that the invention may be more readily understood, reference will now be made to the following more particular description of the invention, examples of which are set forth below. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The mixed waste water for the electroplating and passivation of the alkaline zinc-nickel alloy comprises alkaline zinc-nickel alloy electroplating rinsing water, trivalent chromium passivation rinsing water, trivalent grid passivation waste liquid and hexavalent chromium passivation rinsing water.
The equipment used in the following examples of the present invention is conventional equipment, and the main equipment and chemicals are as follows:
the device comprises a basic zinc-nickel alloy electroplating and passivation mixed wastewater adjusting tank, a ferrous feeding tank, a sedimentation tank A, a flocculation tank A, an inclined tube sedimentation tank A, a sedimentation tank B, a flocculation tank B, an inclined tube sedimentation tank B, a neutralization reaction tank, a biochemical reaction tank and a plate-and-frame filter press.
Ferrous chloride solution: 200g/L ferrous chloride tetrahydrate aqueous solution.
Lime emulsion: the mass concentration of calcium oxide was 80 g/L.
Flocculating agent: and the polyacrylamide aqueous solution with the mass concentration of 5g/L and the model of PAM.
Aqueous sodium dimethyldithiocarbamate solution: the mass concentration is 100 g/L.
Aqueous sodium diethyldithiocarbamate trihydrate: the mass concentration is 100 g/L.
Sodium hydroxide solution: the mass concentration is 100 g/L.
Dilute hydrochloric acid: hydrochloric acid with the mass fraction of 8%.
Example 1: treating mixed waste water of alkaline zinc-nickel alloy electroplating and trivalent chromium passivation
The embodiment provides a method for treating alkaline zinc-nickel alloy electroplating and passivating wastewater, wherein the wastewater contains 20mg/L of nickel ions, 100mg/L of zinc ions and 20mg/L of trivalent chromium ions, and the method comprises the following steps:
step one, precipitating a carboxylic acid coordination agent
And conveying the wastewater from an alkaline zinc-nickel alloy electroplating and passivation mixed wastewater adjusting tank to a ferrous feeding tank, adding dilute hydrochloric acid to adjust the pH to 4-5 under mechanical stirring, and adding 5L of ferrous chloride solution into each ton of wastewater.
And (3) enabling the wastewater to flow into a sedimentation tank A from a ferrous feeding tank, adding lime emulsion under mechanical stirring until the pH value is 10-12, enabling ferrous ions, calcium ions and a carboxylic acid coordination agent to generate precipitates, and enabling trivalent chromium ions, partial zinc ions and ferrous ions to generate hydroxide precipitates.
Step two, precipitation separation
And (3) allowing the wastewater to flow into the flocculation tank A from the sedimentation tank A, adding a flocculating agent under mechanical stirring to flocculate the sediment, and aggregating the sediment into large particles.
The wastewater flows into the inclined tube sedimentation tank A from the flocculation tank A, and the sediment is settled at the bottom of the sedimentation tank. Pumping the precipitate into a plate and frame filter press by a sludge pump, carrying out filter pressing, and enabling the filtrate to flow back to the alkaline zinc-nickel alloy electroplating and passivation mixed wastewater regulating tank. The filter residue is treated by qualified professional manufacturers.
Step three, precipitating heavy metal ions
And (3) enabling the supernatant in the inclined tube sedimentation tank A to flow into a sedimentation tank B, adding dilute hydrochloric acid to adjust the pH value of the wastewater to 4.5-5.5 under the mechanical stirring, adding 20 liters of sodium dimethyldithiocarbamate solution into each ton of wastewater, and generating precipitates from nickel ions, cobalt ions and zinc ions.
Step four, precipitation separation
And (3) enabling the wastewater to flow into a flocculation tank B from the sedimentation tank B, adding a flocculating agent under mechanical stirring to enable the sediment to flocculate, and enabling the sediment to aggregate into large particles.
And the wastewater flows into the inclined tube sedimentation tank B from the flocculation tank B, and the sediment is settled at the bottom of the sedimentation tank. Pumping the precipitate into a plate and frame filter press by a sludge pump, carrying out filter pressing, and enabling the filtrate to flow back to the alkaline zinc-nickel alloy electroplating and passivation mixed wastewater regulating tank. The filter residue is treated by qualified professional manufacturers.
Step five, neutralization treatment
And (3) enabling the supernatant in the inclined tube sedimentation tank B to flow into a neutralization reaction tank, stirring the tank liquid, and adding a sodium hydroxide solution to adjust the pH value to 6-8.
Step six, reducing COD in the wastewater
And (4) allowing the wastewater to flow into a biochemical reaction tank from the neutralization reaction tank, adding strains, and reacting for 8-24 hours.
Step seven, discharging waste water
And discharging the treated alkaline zinc-nickel alloy electroplating and passivating mixed wastewater from a water outlet of the equipment.
Example 2: treating mixed waste water of alkaline zinc-nickel alloy electroplating and low-chromium hexavalent chromium passivation
The embodiment provides a method for treating alkaline zinc-nickel alloy electroplating and passivating wastewater, wherein the wastewater contains 20mg/L of nickel ions, 100mg/L of zinc ions, 50mg/L of hexavalent chromium and 20mg/L of trivalent chromium ions, and the method comprises the following steps:
step one, precipitating a carboxylic acid coordination agent
And conveying the wastewater from an alkaline zinc-nickel alloy electroplating and passivation mixed wastewater adjusting tank to a ferrous feeding tank, adding dilute hydrochloric acid to adjust the pH to 4-5 under mechanical stirring, and adding 8L of ferrous chloride solution into each ton of wastewater.
And (3) enabling the wastewater to flow into a sedimentation tank A from a ferrous feeding tank, adding lime emulsion under mechanical stirring until the pH value is 10-12, enabling ferrous ions, calcium ions and a carboxylic acid coordination agent to generate precipitates, and enabling trivalent chromium ions, partial zinc ions and ferrous ions to generate hydroxide precipitates.
Step two, precipitation separation
And (3) allowing the wastewater to flow into the flocculation tank A from the sedimentation tank A, adding a flocculating agent under mechanical stirring to flocculate the sediment, and aggregating the sediment into large particles.
The wastewater flows into the inclined tube sedimentation tank A from the flocculation tank A, and the sediment is settled at the bottom of the sedimentation tank. Pumping the precipitate into a plate and frame filter press by a sludge pump, carrying out filter pressing, and enabling the filtrate to flow back to the alkaline zinc-nickel alloy electroplating and passivation mixed wastewater regulating tank. The filter residue is treated by qualified professional manufacturers.
Step three, precipitating heavy metal ions
And (3) enabling the supernatant in the inclined tube sedimentation tank A to flow into a sedimentation tank B, adding dilute hydrochloric acid to adjust the pH value of the wastewater to 4.5-5.5 under the mechanical stirring, adding 30 liters of sodium diethyldithiocarbamate trihydrate solution into each ton of wastewater, and generating precipitates from nickel ions, cobalt ions and zinc ions.
Step four, precipitation separation
And (3) enabling the wastewater to flow into a flocculation tank B from the sedimentation tank B, adding a flocculating agent under mechanical stirring to enable the sediment to flocculate, and enabling the sediment to aggregate into large particles.
And the wastewater flows into the inclined tube sedimentation tank B from the flocculation tank B, and the sediment is settled at the bottom of the sedimentation tank. Pumping the precipitate into a plate and frame filter press by a sludge pump, carrying out filter pressing, and enabling the filtrate to flow back to the alkaline zinc-nickel alloy electroplating and passivation mixed wastewater regulating tank. The filter residue is treated by qualified professional manufacturers.
Step five, neutralization treatment
And (3) enabling the supernatant in the inclined tube sedimentation tank B to flow into a neutralization reaction tank, stirring the tank liquid, and adding a sodium hydroxide solution to adjust the pH value to 6-8.
Step six, reducing COD in the wastewater
And (4) allowing the wastewater to flow into a biochemical reaction tank from the neutralization reaction tank, adding strains, and reacting for 8-24 hours.
Step seven, discharging waste water
And discharging the treated alkaline zinc-nickel alloy electroplating and passivating mixed wastewater from a water outlet of the equipment.
Test example 1: reduction of hexavalent chromium with ferrous chloride under alkaline conditions
200mg/L of chromium trioxide solution 1L is prepared, wherein the chromium content is 104 mg/L.
Adding 20mL of ferrous chloride solution into the chromium trioxide solution, adding lime emulsion to adjust the pH value to 11, reducing hexavalent chromium into trivalent chromium by ferrous ions and generating chromium hydroxide precipitate, and generating the ferrous hydroxide precipitate by the residual ferrous chloride. Filtering the test solution with quantitative filter paper after 60min to obtain filtrate, and measuring hexavalent chromium in the filtrate by using a diphenyl formylhydrazine spectrophotometry to obtain hexavalent chromium with the mass concentration of 0.032mg/L and the removal rate of 99.97%. Tests show that the treatment method of the alkaline zinc-nickel alloy electroplating and passivating mixed wastewater can effectively remove hexavalent chromium and meet the requirements of Table 3 in GB21900-2008 standard.
Test example 2: independent treatment of alkaline zinc-nickel alloy electroplating wastewater with chelating agent
Preparing a test solution: 10mL of alkaline zinc-nickel alloy electroplating solution in an electroplating plant is sucked and diluted to 1L by adding water.
Adding 30mL of sodium diethyldithiocarbamate trihydrate solution into the test solution, adding dilute hydrochloric acid to adjust the pH value to 5, stirring uniformly, and filtering after 30min to obtain a filtrate. The filtrate was measured by atomic absorption spectrometry to obtain a nickel mass concentration of 0.23mg/L and a zinc mass concentration of 1.75 mg/L. The test solution does not meet the requirements of table 3 in the GB21900-2008 standard after being treated.
Test example 3: the result of the invention for treating the mixed waste water of the electroplating and the passivation of the alkaline zinc-nickel alloy
Preparing a test solution: 10mL of alkaline zinc-nickel alloy electroplating solution in an electroplating plant and 10mL of trivalent chromium passivation solution are sucked together and then diluted to 1L by adding water.
Adding dilute hydrochloric acid to adjust the pH of the test solution to 5, adding 5mL of ferrous chloride solution, adding lime emulsion to adjust the pH to 11, filtering after 30min, then adding 20mL of sodium dimethyldithiocarbamate solution into the filtrate, adding dilute hydrochloric acid to adjust the pH to 5, stirring uniformly, and filtering after 30min to obtain the filtrate. The filtrate was measured by atomic absorption spectrometry to obtain a nickel mass concentration of 0.08mg/L, a zinc mass concentration of 0.43 mg/L, a chromium mass concentration of 0.24mg/L, and a cobalt mass concentration of 0.12 mg/L. The nickel, zinc and chromium after the test solution treatment meet the requirements of table 3 in the GB21900-2008 standard.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. The method for treating the alkaline zinc-nickel alloy electroplating and passivating mixed wastewater is characterized by comprising the following steps of:
(1) under mechanical stirring, adding diluted hydrochloric acid into the mixed wastewater of the alkaline zinc-nickel alloy electroplating and passivation to adjust the pH value to 4-6, and adding a ferrous chloride solution;
(2) under mechanical stirring, adding lime emulsion into the wastewater treated in the step (1) to adjust the pH value to 10-12, and generating precipitates from a carboxylic acid coordination agent and part of heavy metal ions in the wastewater;
(3) adding a flocculating agent into the wastewater treated in the step (2) to enable precipitates to aggregate into large particles and then settle;
(4) filtering, and removing the precipitate treated in the step (3);
(5) under mechanical stirring, adding acid to adjust the pH value of the wastewater treated in the step (4) to 4.5-5.5, adding a chelating agent, and generating a precipitate by heavy metal ions;
(6) adding a flocculating agent into the wastewater treated in the step (5) to enable precipitates to aggregate into large particles and then settle;
(7) filtering, and removing the precipitate treated in the step (6);
(8) and (3) adding an alkali solution into the wastewater treated in the step (7) under mechanical stirring to adjust the pH to 6-8, and reducing COD by a biochemical method.
2. The method for treating the alkaline zinc-nickel alloy electroplating and passivating mixed wastewater as claimed in claim 1, wherein the ferrous chloride solution in the step (1) contains ferrous chloride tetrahydrate with a mass concentration of (150-250) g/L; the volume ratio of the added ferrous chloride solution to the alkaline zinc-nickel alloy electroplating and passivating mixed wastewater is (0.3-2): 100.
3. The method for treating the alkaline zinc-nickel alloy electroplating and passivating mixed wastewater as claimed in claim 1, wherein the mass concentration of calcium oxide in the lime emulsion in the step (2) is (50-100) g/L.
4. The method for treating the alkaline zinc-nickel alloy electroplating and passivating mixed wastewater as claimed in claim 1, wherein the chelating agent in the step (5) is a sodium dimethyldithiocarbamate solution, and the mass concentration of the sodium dimethyldithiocarbamate solution is (80-120) g/L.
5. The method for treating mixed wastewater of alkaline zinc-nickel alloy electroplating and passivation according to claim 4, wherein the volume ratio of the sodium dimethyldithiocarbamate solution added in the step (5) to the wastewater to be treated is (0.5-5): 100.
6. The method for treating the mixed wastewater generated in the electroplating and passivating of the alkaline zinc-nickel alloy according to claim 1, wherein the chelating agent in the step (5) is a sodium diethyldithiocarbamate trihydrate solution, and the mass concentration of the sodium diethyldithiocarbamate solution is (80-120) g/L.
7. The method for treating mixed alkaline zinc-nickel alloy electroplating and passivating wastewater as claimed in claim 6, wherein the volume ratio of the sodium diethyldithiocarbamate trihydrate solution added in the step (5) to the wastewater to be treated is (0.8-8): 100.
8. The method for treating the mixed wastewater of alkaline zinc-nickel alloy electroplating and passivation according to claim 1, wherein the flocculating agent in the step (3) and the step (6) is a polyacrylamide aqueous solution with the mass concentration of (3-8) g/L and the type of PAM.
9. The method for treating the mixed wastewater of the alkaline zinc-nickel alloy electroplating and passivation according to claim 1, wherein dilute hydrochloric acid is used for adjusting the pH in the steps (1) and (5), and the dilute hydrochloric acid is 5-10% of hydrochloric acid in mass fraction; the alkali solution in the step (8) is a sodium hydroxide solution, and the mass concentration of the sodium hydroxide solution is (20-80) g/L.
10. The method for treating mixed wastewater from alkaline zinc-nickel alloy electroplating and passivation according to claim 1, wherein the biochemical process in step (8) is an existing biochemical degradation process.
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| CN112358132A (en) * | 2020-11-06 | 2021-02-12 | 常德市东新金属表面处理有限公司 | Method for treating electroplating wastewater containing cyanogen, zinc and nickel |
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