CN111925012B - Electroplating wastewater treatment process - Google Patents

Electroplating wastewater treatment process Download PDF

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CN111925012B
CN111925012B CN202010789653.8A CN202010789653A CN111925012B CN 111925012 B CN111925012 B CN 111925012B CN 202010789653 A CN202010789653 A CN 202010789653A CN 111925012 B CN111925012 B CN 111925012B
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wastewater
tank
feeding
treatment process
electroplating
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CN111925012A (en
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白少伟
胡拓
潘俊鹏
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Leqing Rongyu Sewage Processing Co ltd
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Leqing Rongyu Sewage Processing Co ltd
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    • C—CHEMISTRY; METALLURGY
    • 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
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • 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
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • 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
    • C02F1/54—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
    • C02F1/56—Macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/70—Treatment of water, waste water, or sewage by reduction
    • C02F1/705—Reduction by metals
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/722—Oxidation by peroxides
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
    • C02F1/72—Treatment of water, waste water, or sewage by oxidation
    • C02F1/725—Treatment of water, waste water, or sewage by oxidation by catalytic oxidation
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/16—Nitrogen compounds, e.g. ammonia
    • C02F2101/18—Cyanides
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/20—Heavy metals or heavy metal compounds
    • C02F2101/22—Chromium or chromium compounds, e.g. chromates
    • C—CHEMISTRY; METALLURGY
    • 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
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2305/00—Use of specific compounds during water treatment
    • C02F2305/02—Specific form of oxidant
    • C02F2305/026—Fenton's reagent

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  • Life Sciences & Earth Sciences (AREA)
  • Hydrology & Water Resources (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Water Supply & Treatment (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Treatment Of Water By Oxidation Or Reduction (AREA)
  • Separation Of Suspended Particles By Flocculating Agents (AREA)

Abstract

The application relates to an electroplating wastewater treatment process, which specifically comprises the following steps: s1, pretreating the cyanide-containing chromium electroplating wastewater; s2, feeding the wastewater into an adjusting tank, and adjusting the pH value of the wastewater; s3, feeding wastewater into a Fenton reaction tank, and adding FeSO into the Fenton reaction tank 4 Reacting for 15min, and adding 25% H 2 O 2 Carrying out oxidative decomposition reaction after the solution; s4, feeding the wastewater into a first flocculation tank, and performing primary flocculation treatment on the wastewater; s5, feeding the wastewater into a reduction tank, and adding a reducing agent into the reduction tank through a dosing system to react for 50-70 min; s6, feeding the wastewater into a flocculation tank II, and performing secondary flocculation treatment on the wastewater; s7, feeding the wastewater into a sedimentation tank, and standing to remove sediments; and S8, filtering the supernatant, and directly discharging the filtrate after reaching the standard. The method has the effect of overcoming the defects of complicated treatment process and low impurity removal efficiency of the cyanide-containing chromium electroplating wastewater.

Description

Electroplating wastewater treatment process
Technical Field
The application relates to the technical field of wastewater treatment, in particular to an electroplating wastewater treatment process.
Background
Electroplating is a process of plating a thin layer of other metals or alloys on the surface of some metals by using the principle of electrolysis, and is a process of attaching a metal film on the surface of a metal or other material workpiece by using the action of electrolysis. The plating film has the function of preventing metal oxidation and can also improve the performances of wear resistance, conductivity, light reflection, corrosion resistance and the like of the metal. Electroplating wastewater is generated in the electroplating process, and the sources of the electroplating wastewater are generally as follows: 1. cleaning water for the plated part; 2. a waste plating solution; 3. other waste waters including flushing the floor of the shop, scrubbing the polar plates, aeration equipment condensation, and various bath liquids and drains that "run, spill, drip, leak" due to bath leakage or improper operation and management; 4. the equipment is cooled by water. The quality and quantity of the electroplating wastewater are related to the process conditions, production load, operation management, water using mode and other factors of electroplating production. The heavy metal components in the electroplating wastewater are complex, and the heavy metal components in the electroplating wastewater are generally required to be known according to electroplating materials, for example, the electroplating wastewater usually contains hexavalent chromium, cyanide and a small amount of nickel ions.
In the industrial treatment of cyanide-containing wastewater and chromium electroplating wastewater, the cyanide-containing wastewater and the chromium electroplating wastewater are usually separated and then mixed, but the treatment process of the cyanide-containing chromium electroplating wastewater containing both cyanide and hexavalent chromium is complicated, and the impurity removal efficiency is not high.
Disclosure of Invention
In order to overcome the defects of complicated treatment process and low impurity removal efficiency of the cyanide-containing chromium electroplating wastewater, the application provides an electroplating wastewater treatment process.
The application provides an electroplating wastewater treatment process, which adopts the following technical scheme:
the electroplating wastewater treatment process specifically comprises the following treatment steps:
s1, pretreating cyanogen-containing chromium-electroplating wastewater, and sequentially feeding the wastewater into an oil removal tank and a filter tank to remove floating oil and impurities in the wastewater;
s2, feeding wastewater into a regulating tank, and adding dilute H into the regulating tank through a dosing system 2 SO 4 Adjusting the pH value of the wastewater by using the solution;
s3, feeding wastewater into the Fenton reaction tank, and adding FeSO into the Fenton reaction tank through a dosing system 4 Reacting for 15min, and adding 25% H 2 O 2 The solution and the waste water stay in the Fenton reaction tank for 40-60 min;
s4, feeding the wastewater into a first flocculation tank, adding a first flocculating agent into the first flocculation tank through a dosing system, stirring to form a flocculating body, and filtering to remove the flocculating body;
s5, feeding the wastewater into a reduction tank, adding a reducing agent into the reduction tank through a dosing system, and reacting for 50-70 min;
s6, feeding the wastewater into a second flocculation tank, and adding Ca (OH) into the second flocculation tank through a dosing system 2 Adjusting the pH value of the wastewater by using the solution or NaOH solution, adding a flocculant II, and stirring to form a flocculating constituent;
s7, feeding the wastewater into a sedimentation tank, standing until a flocculating constituent is settled to the lower part of the sedimentation tank, forming a clear boundary with a supernatant at the upper part of the sedimentation tank, and recovering the flocculating constituent to a sludge treatment system;
s8, filtering the supernatant through a screen filter, a sand filter and an activated carbon filter in sequence, recovering the filtrate to a sludge treatment system, compressing the filtrate together with a flocculating constituent into a filter cake, transporting the filter cake outwards, and directly discharging the filtrate after reaching the standard.
By adopting the technical scheme, after floating oil and impurities with larger diameter in the wastewater containing cyanogen and chromium electroplating are removed, the pH of the wastewater is adjusted and then the wastewater is fed into the reactorIn the Fenton reaction tank, the reason for adjusting the pH is that Fe in the Fenton reaction tank 2+ Precipitates can be generated under alkaline conditions, so that the reaction effect is poor; because the Fenton system has strong oxidation effect, cyanide in the wastewater is oxidized and decomposed into a final product N in the Fenton reaction tank 2 With CO 2 And discharging the waste water to ensure that the cyanide content in the cyanide-containing chromium electroplating waste water reaches the discharge standard; the wastewater enters a flocculation tank I, and the purpose of the wastewater is to remove particles which are difficult to separate or decompose in a part of the wastewater so as to avoid influencing subsequent reaction; because the pH value of the wastewater is still acidic at the moment, the wastewater is directly fed into a reduction tank, and a reducing agent is added to remove Cr in the wastewater 6+ Reduced to Cr 3+ Then adding OH into the wastewater - So that Cr in the wastewater 3 + 、Fe 2+ And Fe 3+ Precipitating the metal ions to thereby make Cr 3+ The content of the metal ions reaches the discharge standard; the addition of the flocculant II is used for further removing particles which are difficult to separate or decompose in the wastewater so as to further reduce the COD content of the wastewater and enable the COD content to reach the discharge standard;
the process is simple to operate, and can be used for treating cyanide and Cr in the electroplating chromium wastewater containing cyanide 6+ And other impurities have good impurity removal effect.
Preferably, the flocculant I in S4 is poly-phosphorus ferric chloride.
By adopting the technical scheme, the high-valence anions in the poly-phosphorus ferric chloride and the Fe generated by oxidation of Fenton reaction in the wastewater 3+ Has strong affinity and can participate in Fe 3+ The complex reaction can bridge between iron atoms to form multi-core complex and then is discharged, thereby greatly reducing Fe in the wastewater 3+ The content of (a); the poly-phosphorus ferric chloride has excellent electric neutralization adsorption bridging effect on the charged particles which are difficult to decompose, so that the flocculation effect of the wastewater is improved, more flocculating constituents are formed, and the treatment effect of the wastewater is improved.
Preferably, the flocculant II in S6 comprises the following components in parts by weight: 30 to 50 portions of acrylamide, 20 to 30 portions of sodium silicate, 10 to 20 portions of hydroxymethyl cellulose, 5 to 15 portions of chitosan and 0.5 to 1.5 portions of potassium persulfate.
By adopting the technical scheme, the flocculant II prepared by copolymerizing acrylamide, sodium silicate, hydroxymethyl cellulose and chitosan has a good flocculation effect, the removal efficiency of ions and particles is high, the flocculant is more easily degraded, and the flocculant has better dispersion uniformity in wastewater.
Preferably, the preparation method of the flocculant II comprises the following steps: 1) Mixing acrylamide and sodium silicate at 25 ℃ and stirring for 40min; 2) Dissolving hydroxymethyl cellulose and chitosan in deionized water, adding the mixture into the solution, stirring for 20min, adding potassium persulfate, and reacting under stirring at 35 deg.C for 8 hr under nitrogen atmosphere to obtain a reaction material; 3) Naturally cooling the reaction material at room temperature for 24h to obtain a crude product; 4) Precipitating and separating the crude product by using an excessive ethanol solvent, and drying to obtain a crude graft; 5) And (3) taking acetone as an extracting agent, placing the crude graft in a Soxhlet extractor for extraction for 9 hours to remove a homopolymer, and drying in vacuum to obtain a flocculant II.
Preferably, the pH in S2 is adjusted to 2 to 3.5.
By adopting the technical scheme, when the pH value of the wastewater is too high, the appearance of OH is limited, and Fe (OH) can appear 2 Precipitation of Fe 2+ Loss of catalytic ability of (a); when the pH value is too low, the catalytic reaction rate is slowed down, and the organic matter oxidative decomposition efficiency is reduced. The pH value of the wastewater is adjusted to 2-3.5, and cyanide in the wastewater has better oxidative decomposition effect in the Fenton reaction tank.
Preferably, H in S3 2 O 2 With Fe 2+ The molar ratio of (6-10): 1.
by adopting the technical scheme, H 2 O 2 With Fe 2+ The molar ratio of (6-10): 1, the cyanide in the wastewater has a better oxidative decomposition effect.
Preferably, the reducing agent in S5 is any one of sodium sulfite, sodium metabisulfite, sodium bisulfite and sodium thiosulfate.
By adopting the technical scheme, the sodium sulfite, the sodium pyrosulfite and the hydrogen sulfiteSodium and sodium thiosulfate are both p-Cr 6+ The method has good reduction effect, and impurities which influence water quality are not introduced; the price of sodium sulfite, sodium pyrosulfite, sodium bisulfite and sodium thiosulfate is lower, and the cost can be saved.
Preferably, a citric acid solution with a concentration of 7% is further added to the S5.
By adopting the technical scheme, the citric acid is dissolved in the water and shows acidity, and is added into the reduction tank, on one hand, the citric acid has a certain regulating effect on the pH value of the wastewater and provides better reaction conditions for the reduction reaction, and on the other hand, the citric acid can be used for Cr 6+ The reduction reaction has certain catalytic promotion effect, and is beneficial to improving Cr 6+ The reduction efficiency of (a).
Preferably, the pH in S6 is adjusted to 10 to 11.
By adopting the technical scheme, under the alkaline condition, OH-in the wastewater reacts with metal cations in the wastewater to generate precipitates, which is beneficial to removing the metal cations. The pH value of the waste water is adjusted to 10-11, and the metal cations have better precipitation reaction effect.
In summary, the present application includes at least one of the following beneficial technical effects:
1. the process firstly removes cyanide in the wastewater containing cyanogen and chromium electroplating, and then removes Cr in the wastewater 6+ The operation process is simple, and the impurity removal effect is good;
2. the poly-phosphorus ferric chloride can participate in Fe 3+ The complex reaction of (2) can bridge among iron atoms to form a polynuclear complex and then is discharged, thereby greatly reducing Fe in the wastewater 3+ The content of (A); the poly-phosphorus ferric chloride has excellent electric neutralization adsorption bridging effect on the negatively charged particles which are difficult to decompose in water, so that the flocculation effect of the wastewater is improved, more floccules are formed, and the treatment effect of the wastewater is improved;
3. the flocculant II prepared by copolymerizing acrylamide, sodium silicate, hydroxymethyl cellulose and chitosan has a good flocculation effect, high removal efficiency of ions and particles, is more easily degraded, and has better dispersion uniformity in wastewater.
Detailed Description
The embodiment of the application discloses an electroplating wastewater treatment process.
Example 1
The electroplating wastewater treatment process specifically comprises the following treatment steps:
s1, pretreating cyanogen-containing chromium-electroplating wastewater, and sequentially feeding the wastewater into an oil removal tank and a filter tank to remove floating oil and impurities in the wastewater;
s2, feeding wastewater into a regulating tank, and adding dilute H into the regulating tank through a dosing system 2 SO 4 Adjusting the pH value of the wastewater to 3 by using the solution;
s3, feeding wastewater into the Fenton reaction tank, and adding FeSO into the Fenton reaction tank through a dosing system 4 Reacting for 15min, and adding 25% H 2 O 2 Solution of H 2 O 2 With Fe 2+ In a molar ratio of 8:1, the retention time of the wastewater in a Fenton reaction tank is 50min;
s4, feeding the wastewater into a first flocculation tank, adding poly-phosphorus ferric chloride into the first flocculation tank through a dosing system, stirring to form a flocculating constituent, and filtering to remove the flocculating constituent;
s5, feeding the wastewater into a reduction pool, and adding sodium bisulfite, sodium bisulfite and Cr into the reduction pool through a dosing system 6+ The mass ratio of (A) to (B) is 4;
s6, feeding the wastewater into a second flocculation tank, and adding Ca (OH) into the second flocculation tank through a dosing system 2 Adjusting the pH value of the wastewater to 10.5 by using the solution or NaOH solution, adding a flocculant II, and stirring to form a flocculating constituent;
s7, feeding the wastewater into a sedimentation tank, standing until a flocculating constituent is settled to the lower part of the sedimentation tank, forming a clear boundary with a supernatant positioned at the upper part of the sedimentation tank, and recovering the flocculating constituent to a sludge treatment system;
s8, filtering the supernatant through a screen filter, a sand filter and an activated carbon filter in sequence, recycling the filtrate to a sludge treatment system, compressing the filtrate together with a flocculating constituent into a filter cake, transporting the filter cake outwards, and directly discharging the filtrate after reaching the standard after detection;
the flocculant II comprises the following components in parts by weight:
40 parts of acrylamide, 25 parts of sodium silicate, 15 parts of hydroxymethyl cellulose, 10 parts of chitosan and 1 part of potassium persulfate;
the preparation method of the flocculant II comprises the following steps: 1) Mixing acrylamide and sodium silicate at 25 deg.C, and stirring for 40min; 2) Dissolving hydroxymethyl cellulose and chitosan in deionized water, adding the mixture into the dissolved solution, stirring for 20min, adding potassium persulfate, stirring at constant temperature of 35 ℃ for reaction for 8h under nitrogen atmosphere to obtain a reaction material; 3) Naturally cooling the reaction material at room temperature for 24h to obtain a crude product; 4) Precipitating and separating the crude product by using an excessive ethanol solvent, and drying to obtain a crude graft; 5) And (3) taking acetone as an extracting agent, placing the crude graft in a Soxhlet extractor for extraction for 9 hours to remove a homopolymer, and drying in vacuum to obtain a flocculant II.
Example 2
An electroplating wastewater treatment process specifically comprises the following treatment steps:
s1, pretreating cyanogen-containing chromium-electroplating wastewater, and sequentially feeding the wastewater into an oil removal tank and a filter tank to remove floating oil and impurities in the wastewater;
s2, feeding wastewater into a regulating tank, and adding dilute H into the regulating tank through a dosing system 2 SO 4 The pH value of the wastewater is adjusted to 2 by the solution;
s3, feeding wastewater into the Fenton reaction tank, and adding FeSO into the Fenton reaction tank through a dosing system 4 Reacting for 15min, and adding 25% H 2 O 2 Solution of H 2 O 2 With Fe 2+ In a molar ratio of 6:1, the retention time of the wastewater in a Fenton reaction tank is 40min;
s4, feeding the wastewater into a first flocculation tank, adding poly-phosphorus ferric chloride into the first flocculation tank through a dosing system, stirring to form a flocculating constituent, and filtering to remove the flocculating constituent;
s5, feeding the wastewater into a reduction tank, adding sodium sulfite into the reduction tank through a dosing system, and reacting for 50min;
s6, feeding the wastewater into a second flocculation tank, and adding Ca (OH) into the second flocculation tank through a dosing system 2 Adjusting the pH value of the wastewater to 10 by using the solution or NaOH solution, adding a flocculant II, and stirring to form a flocculating constituent;
s7, feeding the wastewater into a sedimentation tank, standing until a flocculating constituent is settled to the lower part of the sedimentation tank, forming a clear boundary with a supernatant positioned at the upper part of the sedimentation tank, and recovering the flocculating constituent to a sludge treatment system;
s8, filtering the supernatant through a screen filter, a sand filter and an activated carbon filter in sequence, recovering the filtrate to a sludge treatment system, compressing the filtrate together with a flocculating constituent into a filter cake, transporting the filter cake outwards, and directly discharging the filtrate after reaching the standard after detection;
the flocculant II comprises the following components in parts by weight:
30 parts of acrylamide, 20 parts of sodium silicate, 10 parts of hydroxymethyl cellulose, 5 parts of chitosan and 0.5 part of potassium persulfate;
the preparation method of the flocculant II comprises the following steps: 1) Mixing acrylamide and sodium silicate at 25 deg.C, and stirring for 40min; 2) Dissolving hydroxymethyl cellulose and chitosan in deionized water, adding the mixture into the dissolved solution, stirring for 20min, adding potassium persulfate, stirring at constant temperature of 35 ℃ for reaction for 8h under nitrogen atmosphere to obtain a reaction material; 3) Naturally cooling the reaction material at room temperature for 24h to obtain a crude product; 4) Precipitating and separating the crude product by using an excessive ethanol solvent, and drying to obtain a crude graft; 5) And (3) taking acetone as an extracting agent, placing the crude graft in a Soxhlet extractor for extraction for 9 hours to remove a homopolymer, and drying in vacuum to obtain a flocculant II.
Example 3
An electroplating wastewater treatment process specifically comprises the following treatment steps:
s1, pretreating cyanogen-containing chromium-electroplating wastewater, and sequentially feeding the wastewater into an oil removal tank and a filter tank to remove floating oil and impurities in the wastewater;
s2, feeding wastewater into a regulating tank, and adding dilute H into the regulating tank through a dosing system 2 SO 4 The pH value of the wastewater is adjusted to 3.5 by the solution;
s3, feeding wastewater into the Fenton reaction tank, and adding FeSO into the Fenton reaction tank through a dosing system 4 Reaction for 15minThen 25% H is added 2 O 2 Solution of H 2 O 2 With Fe 2+ The molar ratio of the waste water to the waste water is 10;
s4, feeding the wastewater into a first flocculation tank, adding poly-phosphorus ferric chloride into the first flocculation tank through a dosing system, stirring to form a flocculating constituent, and filtering to remove the flocculating constituent;
s5, feeding the wastewater into a reduction tank, adding sodium metabisulfite into the reduction tank through a dosing system, and reacting for 70min;
s6, feeding the wastewater into a second flocculation tank, and adding Ca (OH) into the second flocculation tank through a dosing system 2 Adjusting the pH value of the wastewater to 11 by using the solution or NaOH solution, adding a flocculant II, and stirring to form a flocculating constituent;
s7, feeding the wastewater into a sedimentation tank, standing until a flocculating constituent is settled to the lower part of the sedimentation tank, forming a clear boundary with a supernatant positioned at the upper part of the sedimentation tank, and recovering the flocculating constituent to a sludge treatment system;
s8, filtering the supernatant through a screen filter, a sand filter and an activated carbon filter in sequence, recovering the filtrate to a sludge treatment system, compressing the filtrate together with a flocculating constituent into a filter cake, transporting the filter cake outwards, and directly discharging the filtrate after reaching the standard after detection;
the flocculant II comprises the following components in parts by weight:
50 parts of acrylamide, 30 parts of sodium silicate, 20 parts of hydroxymethyl cellulose, 15 parts of chitosan and 1.5 parts of potassium persulfate;
the preparation method of the flocculant II comprises the following steps: 1) Mixing acrylamide and sodium silicate at 25 ℃ and stirring for 40min; 2) Dissolving hydroxymethyl cellulose and chitosan in deionized water, adding the mixture into the solution, stirring for 20min, adding potassium persulfate, and reacting under stirring at 35 deg.C for 8 hr under nitrogen atmosphere to obtain a reaction material; 3) Naturally cooling the reaction material at room temperature for 24 hours to obtain a crude product; 4) Precipitating and separating the crude product by using an excessive ethanol solvent, and drying to obtain a crude graft; 5) And (3) taking acetone as an extracting agent, placing the crude graft in a Soxhlet extractor for extraction for 9 hours to remove a homopolymer, and drying in vacuum to obtain a flocculant II.
Example 4
This example differs from example 1 in that sodium thiosulfate was used as the reducing agent in S5.
Example 5
The difference between the present example and example 1 is that a citric acid solution with a concentration of 7% is further added to S5, and the mass ratio of the citric acid solution to sodium bisulfite is 0.2.
Example 6
The difference between this example and example 1 is that the hydroxymethyl cellulose in the flocculant component two was deleted, and the hydroxymethyl cellulose in the flocculant component two preparation method was deleted.
Example 7
This example differs from example 1 in that the sodium silicate in the flocculant component two was deleted, and the sodium silicate in the flocculant component two preparation method was deleted accordingly.
Example 8
The difference between the embodiment and the embodiment 1 is that hydroxymethyl cellulose and chitosan in the two flocculant components are deleted, and hydroxymethyl cellulose and chitosan in the two flocculant preparation method are correspondingly deleted.
Example 9
The difference between this example and example 1 is that sodium silicate and chitosan in the flocculant component two were deleted, and sodium silicate and chitosan in the flocculant component two preparation method were deleted correspondingly.
Example 10
The difference between this example and example 1 is that the flocculant II is acrylamide.
Comparative example 1
The difference between the comparative example and the example 1 is that S3 is eliminated, the cyanide-containing electroplating wastewater is subjected to pH adjustment by S2, the cyanide in the cyanide-containing electroplating wastewater is treated by adopting the conventional primary cyanide breaking and secondary cyanide breaking methods, and then other pollutants in the wastewater are treated by connecting S4 and the subsequent treatment steps.
Performance test
The following performance test was conducted on the filtrates discharged from the electroplating wastewater treated by the treatment processes of examples 1 to 10 and comparative example 1, respectively, and the test results are recorded in table 1.
Cr 6+ And (3) content determination: performing measurement by adopting a multivariate calibration-ultraviolet visible light photometry;
CN - content determination: measuring by ultraviolet-visible spectrophotometry;
Ni 2+ and (3) content determination: measuring by ultraviolet-visible spectrophotometry;
Cu 2+ content determination: measuring by ultraviolet-visible spectrophotometry;
and (3) measuring the COD content: COD removal rate (= (COD before treatment-COD after treatment)/COD before treatment) before and after wastewater treatment is detected by referring to HJ828-2017 bichromate method for determining chemical oxygen demand of water quality.
TABLE 1
Figure BDA0002623298760000071
Figure BDA0002623298760000081
As can be seen from the test data in table 1:
1. in the embodiments 1 to 4, the process parameters and the addition amounts of the two components of the flocculant are properly changed within a proper range, so that the treatment effect of each pollutant in the wastewater is not greatly influenced, various heavy metal ions and cyanides reach the discharge standard, and the COD has a higher removal rate;
2. example 5 treatment of Cr 6+ Adding citric acid solution and Cr as catalyst 6+ The content of (b) is significantly reduced compared to example 1, indicating that the addition of citric acid solution increases Cr 6+ The removal effect of (A) has an obvious promotion effect;
3. in examples 6 to 10, certain adjustment is performed on the added component of the flocculant ii, and experimental data show that the component in the flocculant ii changes, which has a certain effect on the removal effect of cyanide and heavy metal ions, but the degree of the effect is not large, but the effect on COD is large, and the removal rate of COD is significantly reduced compared with the removal rate of COD in example 1, which indicates that when acrylamide, sodium silicate and hydroxymethyl cellulose are cooperatively matched, the treatment effect on COD is better;
4. comparative example 1 treatment of cyanide in wastewater with conventional cyanide breaking method and CN in final wastewater - The content does not reach the discharge standard, which indicates that the treatment effect of the conventional cyanide breaking method on cyanide is far inferior to that of the treatment process in the application.
In conclusion, the electroplating wastewater treatment process disclosed by the invention has excellent removal effect on cyanide and various heavy metal ions in wastewater, and has better pollutant removal effect compared with the conventional method.
The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: equivalent changes in structure, shape and principle of the present application shall be covered by the protection scope of the present application.

Claims (7)

1. The electroplating wastewater treatment process specifically comprises the following treatment steps:
s1, pretreating cyanogen-containing chromium-electroplating wastewater, and sequentially feeding the wastewater into an oil removal tank and a filter tank to remove floating oil and impurities in the wastewater;
s2, feeding wastewater into a regulating tank, and adding dilute H into the regulating tank through a dosing system 2 SO 4 Adjusting the pH value of the wastewater by using the solution;
s3, feeding wastewater into the Fenton reaction tank, and adding FeSO into the Fenton reaction tank through a dosing system 4 Reacting for 15min, and adding 25% H 2 O 2 The solution and the retention time of the wastewater in the Fenton reaction tank are 40-60 min;
s4, feeding the wastewater into a first flocculation tank, adding a first flocculating agent into the first flocculation tank through a dosing system, stirring to form a flocculating body, and filtering to remove the flocculating body;
s5, feeding the wastewater into a reduction tank, adding a reducing agent into the reduction tank through a dosing system, and reacting for 50-70 min;
s6, feeding the wastewater into a second flocculation tank, and adding Ca (OH) into the second flocculation tank through a medicine adding system 2 Adjusting the pH value of the wastewater by using the solution or NaOH solution, adding a flocculant II, and stirring to form a flocculating constituent;
s7, feeding the wastewater into a sedimentation tank, standing until a flocculating constituent is settled to the lower part of the sedimentation tank, forming a clear boundary with a supernatant positioned at the upper part of the sedimentation tank, and recovering the flocculating constituent to a sludge treatment system;
s8, filtering the supernatant through a screen filter, a sand filter and an activated carbon filter in sequence, recovering the filtrate to a sludge treatment system, compressing the filtrate together with a flocculating constituent into a filter cake, transporting the filter cake outwards, and directly discharging the filtrate after reaching the standard after detection;
the flocculant II in the S6 comprises the following components in parts by weight: 30 to 50 portions of acrylamide, 20 to 30 portions of sodium silicate, 10 to 20 portions of hydroxymethyl cellulose, 5 to 15 portions of chitosan and 0.5 to 1.5 portions of potassium persulfate;
the preparation method of the flocculant II comprises the following steps: 1) Mixing acrylamide and sodium silicate at 25 deg.C, and stirring for 40min; 2) Dissolving hydroxymethyl cellulose and chitosan in deionized water, adding the mixture into the dissolved solution, stirring for 20min, adding potassium persulfate, stirring at constant temperature of 35 ℃ for reaction for 8h under nitrogen atmosphere to obtain a reaction material; 3) Naturally cooling the reaction material at room temperature for 24h to obtain a crude product; 4) Precipitating and separating the crude product by using an excessive ethanol solvent, and drying to obtain a crude graft; 5) And (3) taking acetone as an extracting agent, placing the crude graft in a Soxhlet extractor for extraction for 9 hours to remove a homopolymer, and drying in vacuum to obtain a flocculant II.
2. The electroplating wastewater treatment process according to claim 1, wherein the treatment process comprises the following steps: and a flocculating agent I in the S4 is poly-phosphorus ferric chloride.
3. The electroplating wastewater treatment process according to claim 1, characterized in that: and the pH value in the S2 is adjusted to 2-3.5.
4. The electroplating wastewater treatment process according to claim 1, characterized in that: the molar ratio of H2O2 to Fe2+ in S3 is (6-10): 1.
5. the electroplating wastewater treatment process according to claim 1, characterized in that: and the reducing agent in the S5 is any one of sodium sulfite, sodium metabisulfite, sodium bisulfite and sodium thiosulfate.
6. The electroplating wastewater treatment process according to claim 1, characterized in that: and a citric acid solution with the concentration of 7% is also added in the S5.
7. The electroplating wastewater treatment process according to claim 1, wherein the treatment process comprises the following steps: and the pH value in the S6 is adjusted to 10-11.
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