CN115557652B - Zinc-nickel-containing wastewater recycling treatment system and method - Google Patents

Zinc-nickel-containing wastewater recycling treatment system and method Download PDF

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CN115557652B
CN115557652B CN202211406519.0A CN202211406519A CN115557652B CN 115557652 B CN115557652 B CN 115557652B CN 202211406519 A CN202211406519 A CN 202211406519A CN 115557652 B CN115557652 B CN 115557652B
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tank
wastewater
zinc
sludge
nickel
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CN115557652A (en
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黄慧
陈琦
石驰
黄佳伟
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Baowu Water Technology Co Ltd
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Baowu Water Technology 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
    • C02F1/02—Treatment of water, waste water, or sewage by heating
    • C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • C02F1/041—Treatment of water, waste water, or sewage by heating by distillation or evaporation by means of vapour compression
    • 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
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/441—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by reverse osmosis
    • 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
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
    • 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
    • C02F1/48—Treatment of water, waste water, or sewage with magnetic or electric fields
    • C02F1/488—Treatment of water, waste water, or sewage with magnetic or electric fields for separation of magnetic materials, e.g. magnetic flocculation
    • 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
    • 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
    • C02F2001/007—Processes including a sedimentation step
    • 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
    • C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
    • C02F2001/425—Treatment of water, waste water, or sewage by ion-exchange using cation exchangers
    • 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

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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)
  • Separation Using Semi-Permeable Membranes (AREA)
  • Removal Of Specific Substances (AREA)

Abstract

The invention discloses a zinc-nickel-containing wastewater recycling treatment system and method, comprising a wastewater regulating tank, a primary pH regulating tank, a primary mixing flocculation tank, a primary efficient sedimentation tank, a secondary pH regulating tank, a secondary mixing flocculation tank, a secondary efficient sedimentation tank, a sludge storage tank, a plate-and-frame filter press, a multi-media filter, ultrafiltration, weak acid cation resin, a reverse osmosis device, an MVR evaporation concentration crystallization device and a freezing melting crystallization device. The scheme of the invention can ensure that the water quality of the effluent can reach the water quality index of industrial water, meets the purpose of recycling wastewater, and can recycle zinc mud and anhydrous sodium sulfate with higher purity. The scheme of the invention has stable treatment effect, high equipment automation operation degree and simple and convenient operation.

Description

Zinc-nickel-containing wastewater recycling treatment system and method
Technical Field
The invention relates to the technical field of water treatment, in particular to a zinc-nickel-containing wastewater recycling treatment system and method.
Background
In recent years, the economy of China rapidly develops, and industrial production enters into the vigorous development stage. While creating economic benefits, there are also increasing environmental concerns. The wastewater recycling treatment is the sustainable development of industrial production, and the win-win of economy and environment is realized.
The cold-rolled sheet is treated by an electrolytic process after degreasing and pickling to realize a surface coating. After electroplating, the surface of the cold-rolled sheet is required to be cleaned, and the cleaning waste liquid is generally electroplating liquid with lower concentration. The cold rolling zinc-nickel-containing wastewater is electroplating cleaning waste liquid, has relatively fixed components, mainly comprises zinc sulfate and nickel sulfate, and contains a small amount of pollutants such as iron ions, calcium ions, chloride ions, oils and the like.
The traditional treatment scheme of cold rolling zinc-nickel-containing wastewater adopts a lime precipitation process, heavy metals zinc and nickel are changed into hydroxide precipitates, solid-liquid separation is carried out in a sedimentation tank or a tubular microfiltration membrane, sludge is sent into a plate-and-frame filter press for dehydration treatment, and the sludge is treated outside a dangerous waste commission. The traditional treatment method has good effect of removing metal ions, but the addition cost of the medicament is high, the ions are required to be additionally added into the existing wastewater, the conductivity and hardness of the wastewater are improved, the advanced treatment of the later-stage wastewater is not facilitated, the secondary pollution is caused by large sludge production, and the waste of resources is caused.
In order to realize sustainable development of enterprises and enable resources to be efficiently and circularly utilized, a scheme for recycling cold-rolled zinc-nickel-containing wastewater is needed.
It should be noted that the information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
Disclosure of Invention
The invention aims to provide a zinc-nickel-containing wastewater recycling treatment system and method, which are used for solving the problems that the traditional treatment scheme of the zinc-nickel-containing wastewater in the prior art is easy to cause secondary pollution and serious in resource waste.
In order to solve the technical problems, the invention provides a zinc-nickel-containing wastewater recycling treatment system which comprises a wastewater regulating tank, a primary pH regulating tank, a primary mixing flocculation tank, a primary efficient sedimentation tank, a secondary pH regulating tank, a secondary mixing flocculation tank, a secondary efficient sedimentation tank, a sludge storage tank, a plate-and-frame filter press, a final neutralization tank, a multi-medium filter, an ultrafiltration device, weak acid cation resin, a reverse osmosis device, an MVR evaporation crystallization device, a freeze-melting crystallization device and a mixed salt drying device;
the waste water regulating tank is used for receiving waste water, so that the waste water is mixed in the waste water regulating tank in a homogeneous way and is output to the primary pH regulating tank;
The primary pH adjusting tank adjusts the pH of the wastewater to 7.5-8.0 by adding sodium hydroxide to form zinc hydroxide precipitate, and outputs the wastewater to the primary mixing flocculation tank;
the primary mixed flocculation tank comprises ferric polymers and magnetic powder, the wastewater is coagulated with an anionic polymeric flocculant in the primary mixed flocculation tank to form large-particle flocs, and the wastewater is output to the primary efficient sedimentation tank;
The first-stage efficient sedimentation tank is used for carrying out solid-liquid separation on the wastewater, zinc-containing sludge is partially refluxed into the first-stage mixing flocculation tank through a reflux sludge pump, and partially discharged into a shearing machine and a magnetic powder collector through a residual sludge pump, the collected magnetic powder returns into the first-stage mixing flocculation tank, zinc hydroxide sludge is discharged into a zinc sludge storage tank, dehydrated through a plate-and-frame filter press, recycled and output the wastewater to the second-stage pH adjustment tank;
The secondary pH adjusting tank is used for adjusting the pH of the wastewater to 9.5-10.0 by adding sodium hydroxide to form nickel hydroxide precipitate, and outputting the wastewater to the secondary mixing flocculation tank;
The secondary mixing flocculation tank is used for adding sodium carbonate, adding a small amount of polyiron and PAM according to the condition of floccule particles, and outputting the wastewater to the secondary efficient sedimentation tank;
the secondary efficient sedimentation tank is used for carrying out solid-liquid separation on the wastewater, and the mixed sludge containing nickel and calcium carbonate is partially refluxed into the secondary mixed flocculation tank through a reflux sludge pump and outputs the wastewater to the final neutralization tank;
The sludge storage pool is used for receiving mixed sludge, and the mixed sludge is subjected to outward transportation treatment after being dehydrated by the plate-and-frame filter press;
The final neutralization tank is used for adding sulfuric acid, adjusting the pH to 6.5-7, and outputting the pH to the multi-medium filter;
The multi-medium filter and the ultrafiltration device are used for removing small particle suspended matters so that the water SDI is less than or equal to 3;
The weak acid cationic resin is used for reducing the heavy metal content in the wastewater;
The reverse osmosis device is used for concentrating the wastewater in a reduced amount, and the produced water meets the industrial water recycling standard;
The MVR evaporation crystallization device is used for controlling the concentration of discharged concentrated solution in the evaporation process, discharging the concentrated solution into a thickener, and dehydrating the concentrated solution by a centrifugal machine to obtain anhydrous sodium sulfate;
The freezing and melting crystallization device is used for reducing the impurity salt amount, the mother solution of the MVR evaporation crystallization device is sent into the freezing and melting crystallization device, the temperature is quickly reduced to minus 5 ℃ to 0 ℃ for crystallization, and the discharged material is reduced by Wen Jingjiang, and sodium sulfate decahydrate solid is obtained after filtering and dehydration. Discharging sodium sulfate decahydrate into a nitrate dissolving tank, re-melting and evaporating, controlling the self-dissolving concentration to be 35-40% of sodium sulfate solution, and centrifugally dehydrating to obtain anhydrous sodium sulfate;
The mixed salt drying device is used for receiving cold nitrate liquid and changing the cold nitrate liquid into mixed salt for outward transportation.
Optionally, a perforated aeration pipe is arranged at the bottom of the wastewater regulating tank.
Optionally, the perforated aerator pipe is made of UPVC, the holes of the perforated aerator pipe are downwards and are arranged in a 45-degree crossed manner with the vertical line, and the aperture is 3mm.
Optionally, 10% sodium hydroxide is used as the pH adjusting agent in the primary pH adjusting tank.
Optionally, the primary mixed flocculation tank is added with magnetic powder and coagulant, wherein the concentration of the magnetic powder in the primary mixed flocculation tank is kept at 8-12g/L, the magnetic powder is added at 200-500ppm, the coagulant is polyiron, the adding amount is 100-200 ppm, and the adding amount of the primary mixed flocculation tank is 1-3ppm.
Optionally, part of sludge in the first-stage efficient sedimentation tank flows back into the first-stage mixing flocculation tank, the amount of the returned sludge is 10-20m < 3 >/h, the residual sludge is lifted to a shearing machine through a pump, sludge flocs are destroyed and then sent to a magnetic drum recoverer, and the magnetic powder is recovered and returned to the first-stage mixing flocculation tank.
Optionally, coagulant is added into the primary mixing flocculation tank, wherein the coagulant is polyiron, and the adding amount is 50-100 ppm. Sodium carbonate and an anionic polymeric flocculant are added into the primary mixing flocculation tank, the adding amount of the sodium carbonate is determined according to the hardness of the inlet water, and the adding amount of the anionic polymeric flocculant is 0.1-0.5 ppm.
Optionally, the final neutralization tank is regulated by 10% dilute sulfuric acid, and the pH is controlled to be 6.5-7.
Optionally, the filter material of the multi-medium filter is quartz sand and anthracite.
Optionally, the operation time of the multi-medium filter is 24 hours, the air-water backwashing is carried out for 1 time, and the air-water backwashing time is 10-15 minutes.
Optionally, the ultrafiltration device adopts external pressure type ultrafiltration and dead-end filtration.
Optionally, the running time of the ultrafiltration device is 30min, the air-water backwashing is carried out for 1 time, and the air-water backwashing time is 5-6min.
Optionally, after the weak acid cation resin is adsorbed and saturated, 4-5% sulfuric acid and 4-5% sodium hydroxide are used for regeneration, and the adsorption liquid is returned to the wastewater regulating tank.
Optionally, the reverse osmosis device adopts a pollution-resistant reverse osmosis membrane.
Optionally, the MVR evaporation crystallization device adopts waste heat steam for evaporation, and the concentration of the discharged concentrated solution is controlled to be 20-25%.
Optionally, the salt drying device adopts a vacuum rake dryer or a roller dryer, the feeding concentration is 25-30%, and the freezing crystallization concentrated cold nitrate solution is processed.
Based on the same inventive concept, the invention also provides a zinc-nickel-containing wastewater recycling treatment method, which utilizes any one of the above characteristic descriptions to realize the zinc-nickel-containing wastewater recycling treatment system, and the zinc-nickel-containing wastewater recycling treatment method comprises the following steps:
The waste water regulating tank receives waste water, so that the waste water is mixed in the waste water regulating tank in a homogeneous way and is output to the primary pH regulating tank;
The primary pH adjusting tank adjusts the pH of the wastewater to 7.5-8.0 by adding sodium hydroxide to form zinc hydroxide precipitate, and outputs the wastewater to the primary mixing flocculation tank;
the primary mixed flocculation tank comprises ferric polymers and magnetic powder, the wastewater is coagulated with an anionic polymeric flocculant in the primary mixed flocculation tank to form large-particle flocs, and the wastewater is output to the primary efficient sedimentation tank;
The primary high-efficiency sedimentation tank is used for carrying out solid-liquid separation on the wastewater, zinc-containing sludge is partially refluxed into the primary mixing flocculation tank through a reflux sludge pump, and partially discharged into a shearing machine and a magnetic powder collector through a residual sludge pump, the collected magnetic powder returns into the primary mixing flocculation tank, zinc hydroxide sludge is discharged into a zinc sludge storage tank, dehydrated through a plate-and-frame filter press, recycled, and the wastewater is output to the secondary pH adjustment tank;
The secondary pH adjusting tank adjusts the pH of the wastewater to 9.5-10.0 by adding sodium hydroxide to form nickel hydroxide precipitate, and outputs the wastewater to the secondary mixing flocculation tank;
The secondary mixing flocculation tank is used for adding sodium carbonate, adding a small amount of polyiron and PAM according to the condition of floccule particles, and outputting the wastewater to the secondary efficient sedimentation tank;
the secondary efficient sedimentation tank carries out solid-liquid separation on the wastewater, and mixed sludge containing nickel and calcium carbonate is partially refluxed into the secondary mixed flocculation tank through a reflux sludge pump and outputs the wastewater to the final neutralization tank;
The sludge storage pool receives the mixed sludge, and the mixed sludge is transported and disposed after being dehydrated by the plate-and-frame filter press;
Sulfuric acid is added into the final neutralization tank, the pH value is adjusted back to 6.5-7, and the pH value is output to the multi-medium filter;
the multi-medium filter and the ultrafiltration device remove small particle suspended matters so that the effluent SDI is less than or equal to 3;
The weak acid cationic resin is used for reducing the heavy metal content in the wastewater;
the reverse osmosis device reduces and concentrates the wastewater, and the produced water meets the industrial water recycling standard;
The MVR evaporation crystallization device discharges concentrated solution into a thickener by controlling the concentration of discharged concentrated solution in the evaporation process, and dehydrates the concentrated solution by a centrifugal machine to obtain anhydrous sodium sulfate;
the freezing and melting crystallization device reduces the impurity salt amount, the mother liquor of the MVR evaporation crystallization device is sent into the freezing and melting crystallization device, the temperature is quickly reduced to minus 5 ℃ to 0 ℃ for crystallization, and the discharged material is reduced by Wen Jingjiang, and sodium sulfate decahydrate solid is obtained after filtration and dehydration. Discharging sodium sulfate decahydrate into a nitrate dissolving tank, re-melting and evaporating, controlling the self-dissolving concentration to be 35-40% of sodium sulfate solution, and centrifugally dehydrating to obtain anhydrous sodium sulfate;
the mixed salt drying device receives cold nitrate liquid and changes the cold nitrate liquid into mixed salt for outward transportation.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention provides a zinc-nickel-containing wastewater recycling treatment system which has stable treatment effect and simple operation and operation, ensures that effluent meets the industrial water quality standard, completely recycles wastewater, and recovers zinc hydroxide and anhydrous sodium sulfate with higher purity to realize the recycling utilization of zinc-nickel-containing wastewater;
2. the invention provides a zinc-nickel-containing wastewater recycling treatment system, which reduces the sludge production as much as possible and reduces the treatment cost of dangerous wastes;
3. The invention provides a zinc-nickel-containing wastewater recycling treatment system, which realizes zero emission of wastewater, and a small amount of evaporation mother liquor is evaporated to form a small amount of mixed salt and is solidified.
The zinc-nickel-containing wastewater recycling treatment method provided by the invention and the zinc-nickel-containing wastewater recycling treatment system belong to the same invention conception, so that the zinc-nickel-containing wastewater recycling treatment method has the same beneficial effects and is not described in detail herein.
Drawings
Fig. 1 is a schematic structural diagram of a zinc-nickel-containing wastewater recycling treatment system according to an embodiment of the present invention.
Detailed Description
Specific embodiments of the present invention will be described in more detail below with reference to the drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention.
In the description of the present invention, it should be understood that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", etc., are based on the directions or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
Referring to fig. 1, an embodiment of the invention provides a zinc-nickel-containing wastewater recycling treatment system, which comprises a wastewater regulating tank, a primary pH regulating tank, a primary mixing flocculation tank, a primary efficient sedimentation tank, a secondary pH regulating tank, a secondary mixing flocculation tank, a secondary efficient sedimentation tank, a sludge storage tank, a plate-and-frame filter press, a final neutralization tank, a multi-medium filter, an ultrafiltration device, weak acid cation resin, a reverse osmosis device, an MVR evaporation crystallization device, a freeze-melting crystallization device and a mixed salt drying device;
the waste water regulating tank is used for receiving waste water, so that the waste water is mixed in the waste water regulating tank in a homogeneous way and is output to the primary pH regulating tank;
The primary pH adjusting tank adjusts the pH of the wastewater to 7.5-8.0 by adding sodium hydroxide to form zinc hydroxide precipitate, and outputs the wastewater to the primary mixing flocculation tank;
the primary mixed flocculation tank comprises ferric polymers and magnetic powder, the wastewater is coagulated with an anionic polymeric flocculant in the primary mixed flocculation tank to form large-particle flocs, and the wastewater is output to the primary efficient sedimentation tank;
The first-stage efficient sedimentation tank is used for carrying out solid-liquid separation on the wastewater, zinc-containing sludge is partially refluxed into the first-stage mixing flocculation tank through a reflux sludge pump, and partially discharged into a shearing machine and a magnetic powder collector through a residual sludge pump, the collected magnetic powder returns into the first-stage mixing flocculation tank, zinc hydroxide sludge is discharged into a zinc sludge storage tank, dehydrated through a plate-and-frame filter press, recycled and output the wastewater to the second-stage pH adjustment tank;
The secondary pH adjusting tank is used for adjusting the pH of the wastewater to 9.5-10.0 by adding sodium hydroxide to form nickel hydroxide precipitate, and outputting the wastewater to the secondary mixing flocculation tank;
The secondary mixing flocculation tank is used for adding sodium carbonate, adding a small amount of polyiron and PAM according to the condition of floccule particles, and outputting the wastewater to the secondary efficient sedimentation tank;
the secondary efficient sedimentation tank is used for carrying out solid-liquid separation on the wastewater, and the mixed sludge containing nickel and calcium carbonate is partially refluxed into the secondary mixed flocculation tank through a reflux sludge pump and outputs the wastewater to the final neutralization tank;
The sludge storage pool is used for receiving mixed sludge, and the mixed sludge is subjected to outward transportation treatment after being dehydrated by the plate-and-frame filter press;
The final neutralization tank is used for adding sulfuric acid, adjusting the pH to 6.5-7, and outputting the pH to the multi-medium filter;
The multi-medium filter and the ultrafiltration device are used for removing small particle suspended matters so that the water SDI is less than or equal to 3;
The weak acid cationic resin is used for reducing the heavy metal content in the wastewater;
The reverse osmosis device is used for concentrating the wastewater in a reduced amount, and the produced water meets the industrial water recycling standard;
The MVR evaporation crystallization device is used for controlling the concentration of discharged concentrated solution in the evaporation process, discharging the concentrated solution into a thickener, and dehydrating the concentrated solution by a centrifugal machine to obtain anhydrous sodium sulfate;
The freezing and melting crystallization device is used for reducing the impurity salt amount, the mother solution of the MVR evaporation crystallization device is sent into the freezing and melting crystallization device, the temperature is quickly reduced to minus 5 ℃ to 0 ℃ for crystallization, and the discharged material is reduced by Wen Jingjiang, and sodium sulfate decahydrate solid is obtained after filtering and dehydration. Discharging sodium sulfate decahydrate into a nitrate dissolving tank, re-melting and evaporating, controlling the self-dissolving concentration to be 35-40% of sodium sulfate solution, and centrifugally dehydrating to obtain anhydrous sodium sulfate;
The mixed salt drying device is used for receiving cold nitrate liquid and changing the cold nitrate liquid into mixed salt for outward transportation.
Compared with the prior art, the zinc-nickel-containing wastewater recycling treatment system has the advantages that the treatment effect is stable, the operation is simple and convenient, the effluent meets the industrial water quality standard, the wastewater is completely recycled, and zinc hydroxide and sodium sulfate with higher purity are recycled, so that the zinc-nickel-containing wastewater recycling is realized; the sludge production is reduced as much as possible, and the treatment cost of dangerous waste is reduced; the scheme of the application can also realize zero emission of wastewater, and a small amount of evaporation mother liquor is evaporated to form a small amount of mixed salt, so that the wastewater is solidified.
Specifically, in this embodiment, a perforated aeration pipe is provided at the bottom of the wastewater adjustment tank.
Specifically, in this embodiment, the perforated aerator pipe is made of UPVC, and the holes of the perforated aerator pipe are arranged downward at an angle of 45 ° with respect to the vertical line, and the aperture is 3mm.
Specifically, in this example, 10% sodium hydroxide was used as the pH adjusting agent in the primary pH adjusting tank.
Specifically, in the embodiment, the primary mixed flocculation tank is added with magnetic powder and coagulant, wherein the concentration of the magnetic powder in the primary mixed flocculation tank is 8-12g/L, the magnetic powder is added at 200-500ppm, the coagulant is polyiron, the adding amount is 100-200 ppm, and the adding amount of the primary mixed flocculation tank is 1-3ppm.
Specifically, in the embodiment, part of sludge in the first-stage efficient sedimentation tank is refluxed into the first-stage mixing flocculation tank, the amount of the refluxed sludge is 10-20m < 3 >/h, the residual sludge is lifted to a shearing machine through a pump, sludge flocs are destroyed and then sent to a magnetic drum recoverer, and magnetic powder is recovered and then returned to the first-stage mixing flocculation tank.
Specifically, in this embodiment, the first-stage mixing flocculation tank is added with a coagulant, wherein the coagulant is polyiron, and the addition amount is 50-100 ppm. Sodium carbonate and an anionic polymeric flocculant are added into the primary mixing flocculation tank, the adding amount of the sodium carbonate is determined according to the hardness of the inlet water, and the adding amount of the anionic polymeric flocculant is 0.1-0.5 ppm.
Specifically, in this embodiment, the final neutralization tank uses 10% dilute sulfuric acid to adjust back to a pH of 6.5-7.
Specifically, in this embodiment, the filter material of the multi-media filter is quartz sand and anthracite.
Optionally, the operation time of the multi-medium filter is 24 hours, the air-water backwashing is carried out for 1 time, and the air-water backwashing time is 10-15 minutes.
Specifically, in this embodiment, the ultrafiltration device adopts external pressure type ultrafiltration, and dead-end filtration.
Specifically, in this embodiment, the operation time of the ultrafiltration device is 30min, the air-water backwashing is performed for 1 time, and the air-water backwashing time is 5-6min.
Specifically, in this embodiment, after the weak acid cation resin is saturated by adsorption, 4-5% sulfuric acid and 4-5% sodium hydroxide are used for regeneration, and the adsorption solution is returned to the wastewater regulating tank.
Specifically, in this embodiment, the reverse osmosis apparatus employs a reverse osmosis membrane that is resistant to contamination.
Specifically, in this embodiment, the MVR evaporation crystallization device uses waste heat steam to evaporate, and the concentration of the discharged concentrated solution is controlled to be 20-25%.
Specifically, in this embodiment, the salt drying device uses a vacuum rake dryer, the feeding concentration is 25-30%, and the freezing crystallization concentrated cold nitrate solution is processed.
Aiming at the water quality characteristics of cold-rolled zinc-nickel-containing wastewater, the embodiment provides a treatment process system suitable for recycling the zinc-nickel-containing wastewater, and the treatment effect of the scheme is stable, the wastewater can be completely recycled, and zinc hydroxide and anhydrous sodium sulfate with higher purity are recovered, so that the recycling utilization of the zinc-nickel-containing wastewater is realized. The equipment has high automation operation degree, is simple and convenient to operate and operate, and is suitable for industrial production.
The method comprises the following steps:
The parameters of the zinc-nickel-containing wastewater are assumed to be: pH is 1-3, total oil is less than or equal to 3mg/L, suspended matters are less than or equal to 200mg/L, COD is less than or equal to 30mg/L, and hardness is less than or equal to 30mg/L ≤200mg/L,Zn2+≤8000mg/L,Ni2+≤100mg/L,SO4 2-≤8000mg/L,Cl-≤50mg/L,TDS≤15000mg/L.
The treatment process comprises the following steps: the device comprises a wastewater regulating tank, a primary pH regulating tank, a primary mixing flocculation tank, a primary efficient sedimentation tank, a secondary pH regulating tank, a secondary mixing flocculation tank and a secondary efficient sedimentation tank, wherein a sludge storage tank, a plate-and-frame filter press, a multi-medium filter, an ultrafiltration device, weak acid cation resin, a reverse osmosis device, an MVR evaporation crystallization device, a freeze melting crystallization device and a mixed salt drying device.
(1) Waste water regulating tank: the wastewater is discharged into a wastewater regulating tank, and a perforated aeration pipe is arranged at the bottom of the tank to ensure that the incoming water is mixed homogeneously in the regulating tank; the bottom of the regulating tank is provided with a perforated aeration pipe made of UPVC, holes are downwards and are arranged in a 45-degree cross manner with the vertical line, and the aperture is 3mm.
(2) Primary neutralization coagulation flocculation: the wastewater is lifted to a first-stage pH adjusting tank, and the pH is adjusted to 7.5-8.0 by adding sodium hydroxide, so as to form zinc hydroxide precipitate. The wastewater automatically flows to a coagulation tank, added with polyiron and magnetic powder, discharged into a flocculation tank to be coagulated with anionic polymeric flocculant (PAM) to form large-particle flocs. 10% sodium hydroxide is used as a pH adjusting agent, and the pH of the primary pH adjusting tank is controlled to be 7.5-8.0. The first-stage coagulation tank is added with magnetic powder and coagulant, the concentration of the magnetic powder in the coagulation tank is 8-12g/L, and the magnetic powder is 200-500ppm. The coagulant is polyiron, and the adding amount is 100-200 ppm. The anionic polymeric flocculant is added into the flocculation tank, and the addition amount is 1-3ppm.
(3) High-efficiency precipitation: the wastewater automatically flows into a first-stage high-efficiency sedimentation tank for solid-liquid separation, the zinc-containing sludge is partially refluxed into a flocculation tank through a reflux sludge pump, and partially discharged into a shearing machine and a magnetic powder collector through a residual sludge pump, and the collected magnetic powder returns into the flocculation tank. And discharging the zinc hydroxide sludge into a zinc sludge storage pool, and recycling the zinc hydroxide sludge after dehydrating the zinc hydroxide sludge by a plate-and-frame filter press. Part of sludge in the first-stage efficient sedimentation tank is returned to the flocculation tank, and the returned sludge amount is generally 10-20m < 3 >/h; and lifting the surplus sludge to a shearing machine through a pump, destroying sludge flocs, then sending the sludge to a magnetic drum recoverer, and recovering magnetic powder and returning the recovered magnetic powder to a coagulation tank. The recovery rate of the magnetic powder is more than or equal to 95 percent. The zinc hydroxide sludge is discharged into a zinc sludge storage pool, and after being dehydrated by a plate-and-frame filter press, the zinc hydroxide sludge is recycled, and also can be sent into a sludge drying device, so that the water content of the sludge is further reduced, and the later-stage outward transportation is facilitated.
(4) Secondary neutralization coagulation flocculation: the supernatant of the first-stage high-efficiency precipitation flows to a second-stage pH adjusting tank, and the pH is adjusted to 9.5-10.0 by adding sodium hydroxide, so as to form nickel hydroxide precipitation. And (3) automatically flowing the wastewater to a mixing flocculation tank, adding sodium carbonate, and adding a small amount of polyiron and PAM according to the condition of floccule particles. And automatically flowing into a second-stage efficient sedimentation tank for solid-liquid separation. The pH of the secondary pH adjusting tank is controlled to be 9.5-10.0. Coagulant is added into the secondary coagulation tank, the coagulant is polyiron, and the adding amount is 50-100 ppm. Sodium carbonate and an anionic polymeric flocculant are added into the flocculation tank. The adding amount of sodium carbonate is determined according to the hardness of the inflowing water, and the adding amount of the anionic polymeric flocculant is 0.1-0.5 ppm.
(5) Secondary high-efficiency precipitation: the effluent of the secondary neutralization coagulation flocculation tank automatically flows into a secondary efficient sedimentation tank for solid-liquid separation, and the mixed sludge containing nickel and calcium carbonate is partially refluxed into the flocculation tank through a reflux sludge pump, so that the dosage of the medicament is reduced. The mixed sludge is discharged into a mixed sludge storage pool and is transported and disposed after being dehydrated by a plate-and-frame filter press.
(6) Final neutralization tank: the supernatant from the second stage of the efficient precipitation is passed to a final neutralization tank where sulfuric acid is added and the pH is adjusted back to 6.5-7. And finally, the neutralizing tank is regulated back by 10% dilute sulfuric acid, and the pH is controlled to be 6.5-7.
(7) Multi-media filter and ultrafiltration device: the precipitated effluent is lifted to a multi-medium filter and an ultrafiltration device through a pump, and small particle suspended matters are further removed, so that the SDI of the effluent is less than or equal to 3, and the reverse osmosis water inlet requirement is met. The filter materials of the multi-medium filter are quartz sand and anthracite. The operation time is 24 hours, the air-water backwashing is carried out for 1 time, and the backwashing time is about 10-15 minutes. The ultrafiltration device adopts external pressure type ultrafiltration and dead-end filtration. The running time is 30min, and the air-water backwashing time is about 5-6min for 1 time. And (5) carrying out chemical enhanced cleaning regularly according to pollution conditions.
(8) Weak acid cationic resin: the ultrafiltration effluent is lifted to a weak acid cation resin device, so that the heavy metal content (such as calcium, magnesium, zinc, nickel and the like) in the wastewater is further reduced. And (3) after the weak acid cation resin is adsorbed and saturated, 4-5% sulfuric acid and 4-5% sodium hydroxide are adopted for regeneration, and the adsorption liquid is returned to the wastewater regulating tank.
(9) Reverse osmosis device: and (3) setting a secondary reverse osmosis device, reducing and concentrating the wastewater, wherein the produced water meets the industrial water recycling standard. The reverse osmosis device adopts a pollution-resistant reverse osmosis membrane, and the concentrated water TDS is concentrated to about 80g/L through secondary reverse osmosis;
(10) MVR evaporation crystallization: the MVR evaporation crystallization system is lifted by reverse osmosis concentrated water, the concentration (20-25%) of discharged concentrated solution in the evaporation process is controlled, the concentrated solution is discharged into a thickener, and anhydrous sodium sulfate is obtained by centrifugal machine. The condensed water meets the recycling standard of industrial water. MVR evaporation crystallization adopts waste heat steam for evaporation, and the concentration of discharged concentrated solution needs to be controlled to be 20-25%, so that the anhydrous sodium sulfate centrifugal dehydration condition is satisfied; the chloride content of the concentrated mother solution is controlled, and the purity of the anhydrous sodium sulfate is ensured. When the concentration of sodium chloride exceeds 15-18%, mother liquor of MVR evaporation crystallization is continuously fed into a crystallization and freezing system, and is rapidly reduced to-5-0 ℃ and dehydrated to form sodium sulfate decahydrate.
(11) Freezing, melting and crystallizing: in order to reduce the impurity salt amount, the mother solution of MVR evaporation crystallization is continuously fed into a crystallization and freezing system, and is rapidly reduced to-5 ℃ to 0 ℃ for crystallization. Filtering and dehydrating the discharged material low Wen Jingjiang to obtain sodium sulfate decahydrate solid. Discharging sodium sulfate decahydrate into a nitrate dissolving tank, re-melting and evaporating, controlling the self-dissolving concentration to be 35-40% of sodium sulfate solution, and centrifugally dehydrating to obtain anhydrous sodium sulfate. And (5) sending the cold nitrate solution into a mixed salt drying device to change the cold nitrate solution into mixed salt for external transportation. The condensed water meets the recycling standard of industrial water. The mixed salt drying device adopts a vacuum rake dryer, the feeding concentration is 25-30%, and the freezing crystallization concentrated cold nitrate solution is processed.
To facilitate a better understanding of the aspects of the present application, a more specific example is provided below:
The parameters of the zinc-nickel-containing wastewater are the same as those assumed above. The zinc-nickel-containing wastewater recycling treatment system comprises: the device comprises a wastewater regulating tank, a primary pH regulating tank, a primary mixing flocculation tank, a primary efficient sedimentation tank, a secondary pH regulating tank, a secondary mixing flocculation tank and a secondary efficient sedimentation tank, wherein a sludge storage tank, a plate-and-frame filter press, a multi-medium filter, an ultrafiltration device, weak acid cation resin, a reverse osmosis device, an MVR evaporation crystallization device, a freeze melting crystallization device and a mixed salt drying device.
The primary neutralization pH value is 7.5-8, the primary coagulation tank is added with polyferric and magnetic powder, and the polyferric and the magnetic powder are discharged into the flocculation tank to be coagulated with anionic polymeric flocculant (PAM) to form large-particle flocs, so that zinc hydroxide precipitate is formed. The pH value of the secondary neutralization is 9.5-10, the secondary coagulation tank is added with iron, and the secondary flocculation tank is added with sodium carbonate and an anionic polymeric flocculant to form nickel hydroxide and calcium carbonate sediment.
The sludge of the first-stage efficient sedimentation tank is discharged into a shearing machine and a magnetic powder collector, and the collected magnetic powder returns to the coagulation tank. The recovery rate of the magnetic powder is more than or equal to 95 percent. The zinc hydroxide sludge is discharged into a zinc sludge storage pool, and after the zinc hydroxide sludge is dehydrated by a plate-and-frame filter press, the water content of a mud cake is less than or equal to 70 percent, so that the water content of the mud cake is reduced, and the mud cake can be sent into a sludge drying device, so that the water content is less than or equal to 30 percent, and the transportation and the recycling are convenient. The sludge of the second-stage efficient sedimentation tank is mixed sludge, and the main components are nickel hydroxide and calcium carbonate, and the mixed sludge is dewatered by a plate-and-frame filter press and then transported outwards. The plate-and-frame filter presses of two different types of sludge are arranged separately, so that the purity of zinc hydroxide sludge is ensured, and the recycling value is improved. Through analysis and detection, the zinc oxide content in the zinc hydroxide sludge after dehydration treatment is 75-85%, and the rest main impurities are ferric oxide and silicon dioxide (magnetic powder content).
The ultrafiltration device of the embodiment adopts external pressure type ultrafiltration, and the turbidity of the inlet water is preferably less than or equal to 5NTU, so that the front end adopts a multi-medium filter and a self-cleaning filter to intercept larger particle suspended matters. If submerged ultrafiltration is used, the front-end pretreatment may be suitably relaxed.
The weak acid cation resin bed can adopt a fixed bed or a floating bed, and the weak acid cation resin bed adopts a floating bed in the embodiment, and the filtration speed is not more than 25-28m/h. The regeneration process adopts 4-5% sulfuric acid, 4-5% sodium hydroxide and softened water for regeneration. Firstly, regenerating by sulfuric acid, wherein the regeneration flow rate is 2.3-2.5m/h; then water washing is adopted, and the water washing flow rate is 3-3.2m/h; the sodium hydroxide is adopted for transformation, and the regeneration flow rate is 2.3-2.5m/h; finally, water washing is adopted, and the water washing flow rate is 3-3.2m/h.
The reverse osmosis device adopts a pollution-resistant reverse osmosis membrane, the first-stage reverse osmosis is low-pressure reverse osmosis, and the recovery rate is 60-70%, and the concentrated water is concentrated to 35-40g/L; the second-stage reverse osmosis is high-pressure reverse osmosis, the recovery rate is 60% -70%, and the concentrated water TDS is concentrated to 80-10g/L. The low-pressure reverse osmosis produced water and the high-pressure reverse osmosis produced water are mixed and then used as industrial reuse water, and the water quality meets the industrial circulating cooling water treatment design specification (GB/T50050-2017).
The evaporation crystallization process section can select multiple-effect evaporation under the condition of residual heat steam, so that the operation cost is reduced. The embodiment has no waste heat steam resource and adopts a mechanical compression evaporation crystallization process (MVR evaporation crystallization). The concentration and temperature of the materials must be controlled during the operation process, thereby ensuring the purity of the anhydrous sodium sulphate. The anhydrous sodium sulfate quality can meet the standard of class II first-class products in GB/T6009-2014 Standard Table 1 of Industrial anhydrous sodium sulfate.
And finally, freezing, crystallizing and concentrating cold nitrate solution, and carrying out external transportation as mixed salt by a vacuum rake dryer.
Based on the same inventive concept, the invention also provides a zinc-nickel-containing wastewater recycling treatment method, which utilizes any one of the above characteristic descriptions to realize the zinc-nickel-containing wastewater recycling treatment system, and the zinc-nickel-containing wastewater recycling treatment method comprises the following steps:
The waste water regulating tank receives waste water, so that the waste water is mixed in the waste water regulating tank in a homogeneous way and is output to the primary pH regulating tank;
The primary pH adjusting tank adjusts the pH of the wastewater to 7.5-8.0 by adding sodium hydroxide to form zinc hydroxide precipitate, and outputs the wastewater to the primary mixing flocculation tank;
the primary mixed flocculation tank comprises ferric polymers and magnetic powder, the wastewater is coagulated with an anionic polymeric flocculant in the primary mixed flocculation tank to form large-particle flocs, and the wastewater is output to the primary efficient sedimentation tank;
The primary high-efficiency sedimentation tank is used for carrying out solid-liquid separation on the wastewater, zinc-containing sludge is partially refluxed into the primary mixing flocculation tank through a reflux sludge pump, and partially discharged into a shearing machine and a magnetic powder collector through a residual sludge pump, the collected magnetic powder returns into the primary mixing flocculation tank, zinc hydroxide sludge is discharged into a zinc sludge storage tank, dehydrated through a plate-and-frame filter press, recycled, and the wastewater is output to the secondary pH adjustment tank;
The secondary pH adjusting tank adjusts the pH of the wastewater to 9.5-10.0 by adding sodium hydroxide to form nickel hydroxide precipitate, and outputs the wastewater to the secondary mixing flocculation tank;
The secondary mixing flocculation tank is used for adding sodium carbonate, adding a small amount of polyiron and PAM according to the condition of floccule particles, and outputting the wastewater to the secondary efficient sedimentation tank;
the secondary efficient sedimentation tank carries out solid-liquid separation on the wastewater, and mixed sludge containing nickel and calcium carbonate is partially refluxed into the secondary mixed flocculation tank through a reflux sludge pump and outputs the wastewater to the final neutralization tank;
The sludge storage pool receives the mixed sludge, and the mixed sludge is transported and disposed after being dehydrated by the plate-and-frame filter press;
Sulfuric acid is added into the final neutralization tank, the pH value is adjusted back to 6.5-7, and the pH value is output to the multi-medium filter;
the multi-medium filter and the ultrafiltration device remove small particle suspended matters so that the effluent SDI is less than or equal to 3;
The weak acid cationic resin is used for reducing the heavy metal content in the wastewater;
the reverse osmosis device reduces and concentrates the wastewater, and the produced water meets the industrial water recycling standard;
The MVR evaporation crystallization device discharges concentrated solution into a thickener by controlling the concentration of discharged concentrated solution in the evaporation process, and dehydrates the concentrated solution by a centrifugal machine to obtain anhydrous sodium sulfate;
the freezing and melting crystallization device reduces the impurity salt amount, the mother liquor of the MVR evaporation crystallization device is sent into the freezing and melting crystallization device, the temperature is quickly reduced to minus 5 ℃ to 0 ℃ for crystallization, and the discharged material is reduced by Wen Jingjiang, and sodium sulfate decahydrate solid is obtained after filtration and dehydration. Discharging sodium sulfate decahydrate into a nitrate dissolving tank, re-melting and evaporating, controlling the self-dissolving concentration to be 35-40% of sodium sulfate solution, and centrifugally dehydrating to obtain anhydrous sodium sulfate;
the mixed salt drying device receives cold nitrate liquid and changes the cold nitrate liquid into mixed salt for outward transportation.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention provides a zinc-nickel-containing wastewater recycling treatment system which has stable treatment effect and simple operation and operation, ensures that effluent meets the industrial water quality standard, completely recycles wastewater, and recovers zinc hydroxide and anhydrous sodium sulfate with higher purity to realize the recycling utilization of zinc-nickel-containing wastewater;
2. the invention provides a zinc-nickel-containing wastewater recycling treatment system, which reduces the sludge production as much as possible and reduces the treatment cost of dangerous wastes;
3. The invention provides a zinc-nickel-containing wastewater recycling treatment system, which realizes zero emission of wastewater, and a small amount of evaporation mother liquor is evaporated to form a small amount of mixed salt and is solidified.
The zinc-nickel-containing wastewater recycling treatment method provided by the invention and the zinc-nickel-containing wastewater recycling treatment system belong to the same invention conception, so that the zinc-nickel-containing wastewater recycling treatment method has the same beneficial effects and is not described in detail herein.
In the description of the present specification, a description of the terms "one embodiment," "some embodiments," "examples," or "particular examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments. Further, one skilled in the art can engage and combine the different embodiments or examples described in this specification.
The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art will make any equivalent substitution or modification to the technical solution and technical content disclosed in the invention without departing from the scope of the technical solution of the invention, and the technical solution of the invention is not departing from the scope of the invention.

Claims (15)

1. The zinc-nickel-containing wastewater recycling treatment system is characterized by comprising a wastewater regulating tank, a primary pH regulating tank, a primary mixing flocculation tank, a primary efficient sedimentation tank, a secondary pH regulating tank, a secondary mixing flocculation tank, a secondary efficient sedimentation tank, a sludge storage tank, a plate-and-frame filter press, a final neutralization tank, a multi-medium filter, an ultrafiltration device, weak acid cation resin, a reverse osmosis device, an MVR evaporation crystallization device, a freezing and melting crystallization device and a mixed salt drying device;
the waste water regulating tank is used for receiving waste water, so that the waste water is mixed in the waste water regulating tank in a homogeneous way and is output to the primary pH regulating tank;
The primary pH adjusting tank adjusts the pH of the wastewater to 7.5-8.0 by adding sodium hydroxide to form zinc hydroxide precipitate, and outputs the wastewater to the primary mixing flocculation tank;
the primary mixed flocculation tank comprises ferric polymers and magnetic powder, the wastewater is coagulated with an anionic polymeric flocculant in the primary mixed flocculation tank to form large-particle flocs, and the wastewater is output to the primary efficient sedimentation tank;
The first-stage efficient sedimentation tank is used for carrying out solid-liquid separation on the wastewater, zinc-containing sludge is partially refluxed into the first-stage mixing flocculation tank through a reflux sludge pump, and partially discharged into a shearing machine and a magnetic powder collector through a residual sludge pump, the collected magnetic powder returns into the first-stage mixing flocculation tank, zinc hydroxide sludge is discharged into a zinc sludge storage tank, dehydrated through a plate-and-frame filter press, recycled and output the wastewater to the second-stage pH adjustment tank;
The secondary pH adjusting tank is used for adjusting the pH of the wastewater to 9.5-10.0 by adding sodium hydroxide to form nickel hydroxide precipitate, and outputting the wastewater to the secondary mixing flocculation tank;
The secondary mixing flocculation tank is used for adding sodium carbonate, adding a small amount of polyiron and PAM according to the condition of floccule particles, and outputting the wastewater to the secondary efficient sedimentation tank;
the secondary efficient sedimentation tank is used for carrying out solid-liquid separation on the wastewater, and the mixed sludge containing nickel and calcium carbonate is partially refluxed into the secondary mixed flocculation tank through a reflux sludge pump and outputs the wastewater to the final neutralization tank;
The mixed sludge storage pool is used for receiving mixed sludge, and the mixed sludge is subjected to dehydration by the plate-and-frame filter press and then is transported and disposed;
the final neutralization tank is used for adding sulfuric acid, adjusting the pH to 6.5-7, and outputting to the multi-medium filter;
The multi-medium filter and the ultrafiltration device are used for removing small particle suspended matters so that the water SDI is less than or equal to 3;
The weak acid cationic resin is used for reducing the heavy metal content in the wastewater;
The reverse osmosis device is used for concentrating the wastewater in a reduced amount, and the produced water meets the industrial water recycling standard;
The MVR evaporation crystallization device is used for controlling the concentration of discharged concentrated solution in the evaporation process, discharging the concentrated solution into a thickener, and dehydrating the concentrated solution by a centrifugal machine to obtain anhydrous sodium sulfate;
The freezing and melting crystallization device is used for reducing the impurity salt content, the mother solution of the MVR evaporation crystallization device is sent into the freezing and melting crystallization device and is rapidly reduced to-5-0 ℃ for crystallization, sodium sulfate decahydrate solid is obtained after the discharge is low Wen Jingjiang and is filtered and dehydrated, sodium sulfate decahydrate is discharged into a nitrate melting tank, melting and evaporation are carried out again, the autolyzed concentration is controlled to be 35-40% of sodium sulfate solution, and anhydrous sodium sulfate is obtained after centrifugal dehydration;
The mixed salt drying device is used for receiving cold nitrate liquid and changing the cold nitrate liquid into mixed salt for outward transportation;
Wherein, the bottom of waste water equalizing basin is equipped with perforation aeration pipe, adopt 10% sodium hydroxide as pH adjustment medicament in the first-level pH adjustment groove.
2. The zinc-nickel-containing wastewater recycling treatment system according to claim 1, wherein the perforated aerator pipe is made of UPVC, the holes of the perforated aerator pipe are downwards and are arranged at 45-degree intersection with the vertical line, and the aperture is 3mm.
3. The zinc-nickel-containing wastewater recycling treatment system according to claim 1, wherein magnetic powder and coagulant are added into the primary mixing flocculation tank, the concentration of the magnetic powder in the primary mixing flocculation tank is 8-12g/L, the magnetic powder is 200-500ppm, the coagulant is poly-iron, the adding amount is 100-200 ppm, and the adding amount of the anionic polymeric flocculant is 1-3ppm.
4. The zinc-nickel-containing wastewater recycling treatment system according to claim 1, wherein part of sludge in the primary efficient sedimentation tank is refluxed into the primary mixing flocculation tank, and the amount of the refluxed sludge is 10-20And lifting the surplus sludge to a shearing machine through a pump, destroying sludge flocs, then sending the sludge to a magnetic drum recoverer, and recovering magnetic powder and returning the recovered magnetic powder to the primary mixing flocculation tank.
5. The zinc-nickel-containing wastewater recycling treatment system according to claim 1, wherein coagulant is added to the primary mixing flocculation tank, the coagulant is polyiron, the adding amount is 50-100 ppm, sodium carbonate and an anionic polymeric flocculant are added to the primary mixing flocculation tank, the adding amount of sodium carbonate is determined according to the hardness of water inflow, and the adding amount of the anionic polymeric flocculant is 0.1-0.5 ppm.
6. The zinc-nickel-containing wastewater recycling treatment system according to claim 1, wherein the final neutralization tank adopts 10% dilute sulfuric acid callback, and the pH is controlled to be 6.5-7.
7. The zinc-nickel-containing wastewater recycling treatment system according to claim 1, wherein the filter materials of the multi-medium filter are quartz sand and anthracite.
8. The zinc-nickel-containing wastewater recycling treatment system according to claim 7, wherein the multi-medium filter has a running time of 24 hours, is backwashed by air and water for 1 time, and has a backwashed time of 10-15 minutes.
9. The zinc-nickel-containing wastewater recycling treatment system according to claim 1, wherein the ultrafiltration device adopts external pressure type ultrafiltration and dead-end filtration.
10. The zinc-nickel-containing wastewater recycling treatment system according to claim 1, wherein the ultrafiltration device has an operation time of 30min, and is backwashed 1 time by air and water, and the backwashed time by air and water is 5-6min.
11. The zinc-nickel-containing wastewater recycling treatment system according to claim 1, wherein after the weak acid cation resin is adsorbed and saturated, 4-5% sulfuric acid and 4-5% sodium hydroxide are used for regeneration, and adsorption liquid is returned to the wastewater regulating tank.
12. The zinc-nickel-containing wastewater recycling treatment system according to claim 1, wherein the reverse osmosis device adopts a pollution-resistant reverse osmosis membrane.
13. The zinc-nickel-containing wastewater recycling treatment system according to claim 1, wherein the MVR evaporation crystallization device adopts waste heat steam for evaporation, and the concentration of the discharged concentrated solution is controlled to be 20-25%.
14. The zinc-nickel-containing wastewater recycling treatment system according to claim 1, wherein the mixed salt drying device adopts a vacuum rake dryer or a roller dryer, the feeding concentration is 25-30%, and the freezing crystallization concentrated cold nitrate solution is treated.
15. A method for recycling zinc-nickel-containing wastewater, characterized in that the zinc-nickel-containing wastewater recycling treatment system according to any one of claims 1 to 14 is utilized, and the method for recycling zinc-nickel-containing wastewater comprises:
The waste water regulating tank receives waste water, so that the waste water is mixed in the waste water regulating tank in a homogeneous way and is output to the primary pH regulating tank;
The primary pH adjusting tank adjusts the pH of the wastewater to 7.5-8.0 by adding sodium hydroxide to form zinc hydroxide precipitate, and outputs the wastewater to the primary mixing flocculation tank;
the primary mixed flocculation tank comprises ferric polymers and magnetic powder, the wastewater is coagulated with an anionic polymeric flocculant in the primary mixed flocculation tank to form large-particle flocs, and the wastewater is output to the primary efficient sedimentation tank;
The primary high-efficiency sedimentation tank is used for carrying out solid-liquid separation on the wastewater, zinc-containing sludge is partially refluxed into the primary mixing flocculation tank through a reflux sludge pump, and partially discharged into a shearing machine and a magnetic powder collector through a residual sludge pump, the collected magnetic powder returns into the primary mixing flocculation tank, zinc hydroxide sludge is discharged into a zinc sludge storage tank, dehydrated through a plate-and-frame filter press, recycled, and the wastewater is output to the secondary pH adjustment tank;
The secondary pH adjusting tank adjusts the pH of the wastewater to 9.5-10.0 by adding sodium hydroxide to form nickel hydroxide precipitate, and outputs the wastewater to the secondary mixing flocculation tank;
The secondary mixing flocculation tank is used for adding sodium carbonate, adding a small amount of polyiron and PAM according to the condition of floccule particles, and outputting the wastewater to the secondary efficient sedimentation tank;
the secondary efficient sedimentation tank carries out solid-liquid separation on the wastewater, and mixed sludge containing nickel and calcium carbonate is partially refluxed into the secondary mixed flocculation tank through a reflux sludge pump and outputs the wastewater to the final neutralization tank;
The sludge storage pool receives the mixed sludge, and the mixed sludge is transported and disposed after being dehydrated by the plate-and-frame filter press;
sulfuric acid is added into the final neutralization tank, the pH value is adjusted back to 6.5-7, and the pH value is output to the multi-medium filter;
the multi-medium filter and the ultrafiltration device remove small particle suspended matters so that the effluent SDI is less than or equal to 3;
The weak acid cationic resin is used for reducing the heavy metal content in the wastewater;
the reverse osmosis device reduces and concentrates the wastewater, and the produced water meets the industrial water recycling standard;
The MVR evaporation crystallization device discharges concentrated solution into a thickener by controlling the concentration of discharged concentrated solution in the evaporation process, and dehydrates the concentrated solution by a centrifugal machine to obtain anhydrous sodium sulfate;
The freezing and melting crystallization device reduces the impurity salt amount, the mother liquor of the MVR evaporation crystallization device is sent into the freezing and melting crystallization device and is rapidly reduced to-5-0 ℃ for crystallization, sodium sulfate decahydrate solid is obtained after discharging is low Wen Jingjiang and filtering and dewatering, sodium sulfate decahydrate is discharged into a nitrate melting tank, melting and evaporating are carried out again, the self-dissolving concentration is controlled to be 35-40% of sodium sulfate solution, and anhydrous sodium sulfate is obtained after centrifugal dewatering;
the mixed salt drying device receives cold nitrate liquid and changes the cold nitrate liquid into mixed salt for outward transportation.
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