CN113754121A - System and method for treating hydrofluoric acid-containing wastewater - Google Patents

System and method for treating hydrofluoric acid-containing wastewater Download PDF

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CN113754121A
CN113754121A CN202111089500.3A CN202111089500A CN113754121A CN 113754121 A CN113754121 A CN 113754121A CN 202111089500 A CN202111089500 A CN 202111089500A CN 113754121 A CN113754121 A CN 113754121A
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liquid
outlet
inlet
hydrofluoric acid
reverse osmosis
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CN113754121B (en
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武警
吴彩琼
杨恒
田丽森
聂宜文
赵金
刘少非
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China ENFI Engineering Corp
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China ENFI Engineering Corp
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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
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/19—Fluorine; Hydrogen fluoride
    • C01B7/191—Hydrogen fluoride
    • C01B7/195—Separation; Purification
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/19—Fluorine; Hydrogen fluoride
    • C01B7/191—Hydrogen fluoride
    • C01B7/195—Separation; Purification
    • C01B7/196—Separation; Purification by distillation
    • 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
    • C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
    • C02F1/447—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by membrane distillation
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/30—Wastewater or sewage treatment systems using renewable energies
    • Y02W10/37—Wastewater or sewage treatment systems using renewable energies using solar energy

Abstract

The invention provides a system and a method for treating hydrofluoric acid-containing wastewater. The above-mentioned system includes: a solid-liquid separation device, a membrane distillation unit, an ultrafiltration device and a reverse osmosis unit. The solid-liquid separation device is provided with a hydrofluoric acid-containing wastewater feed inlet, a liquid phase outlet and a slurry outlet; the membrane distillation unit is provided with a feed liquid inlet and an enriched liquid outlet, and the feed liquid inlet is communicated with the liquid phase outlet through a liquid phase conveying pipeline; the ultrafiltration device is provided with an enrichment liquid inlet, a concentration liquid outlet and a filtered water outlet, and the enrichment liquid inlet is communicated with the enrichment liquid outlet through an enrichment liquid conveying pipeline; the reverse osmosis unit is provided with a concentrated solution inlet, a hydrofluoric acid outlet and a reverse osmosis residual liquid outlet, and the concentrated solution inlet is communicated with the concentrated solution outlet through a concentrated solution conveying pipeline. Not only can the hydrofluoric acid be recycled, but also the recycling rate of the hydrofluoric acid is improved; the content of fluorinion in the hydrofluoric acid-containing wastewater can be reduced, and the water quality is improved; the system has compact design and can shorten the recovery treatment period of hydrofluoric acid.

Description

System and method for treating hydrofluoric acid-containing wastewater
Technical Field
The invention relates to the technical field of sewage recovery treatment, in particular to a system and a method for treating hydrofluoric acid-containing wastewater.
Background
Hydrofluoric acid is needed in the processes of monocrystalline silicon raw material cleaning, silicon wafer etching, polishing and the like in the photovoltaic industry, and a large amount of hydrofluoric acid-containing wastewater can be generated. Hydrofluoric acid has a low pH value, high corrosivity, high oxidation and high conductivity, and direct discharge causes significant environmental pollution. At present, a precipitation method is mainly adopted for the treatment process of the hydrofluoric acid-containing wastewater, namely, medicaments such as slaked lime, calcium chloride, a coagulant and the like are added into the hydrofluoric acid-containing wastewater to enable fluoride ions and calcium ions to generate calcium fluoride, so that the aim of removing fluorine is fulfilled.
Prior literature (CN103663777A) discloses a method for treating hydrofluoric acid-containing wastewater from a plant. Lime milk is added into hydrofluoric acid wastewater, calcium fluoride is generated by the reaction of calcium chloride in the lime milk and fluoride ions, polyaluminium chloride preparation is added to flocculate the calcium fluoride into alum floc, the alum floc enters an enhanced flocculation tank, and polyacrylamide preparation is added to form blocky precipitate and remove hydrofluoric acid in the wastewater. However, in the above treatment process, calcium ions need to be added to generate calcium fluoride from fluoride ions and calcium ions to remove fluoride ions, which results in increased hardness of water, poor water quality, and easy generation of a large amount of hazardous waste sludge. In addition, all hydrofluoric acid in the treatment process is discharged as waste, so that the hydrofluoric acid cannot be recycled, and resource waste is caused.
In order to solve the problem that hydrofluoric acid cannot be recycled, a conventional document (CN103172199A) discloses a method for treating hydrofluoric acid wastewater. Adding a mixture of lime milk and caustic soda or lime milk into a stock solution of hydrofluoric acid wastewater, taking supernatant, sequentially carrying out primary filtration by using a filter and filtration and separation by using a cross-flow ultrafiltration membrane to obtain concentrated water and filtered water, adding a scale inhibitor into the filtered water, and then carrying out filtration and separation by using a reverse osmosis membrane to obtain waste liquid and reuse water. Although the document utilizes a reverse osmosis membrane to filter and separate the waste liquid, the recovery rate of water can reach 90%, and the concentrated solution obtained after reverse osmosis treatment is circularly treated by the hydrofluoric acid wastewater treatment system. However, although the method can reduce the discharge amount of hydrofluoric acid wastewater and improve the recovery rate of water, the hydrofluoric acid-containing wastewater still needs to be treated and discharged as waste.
On the basis, the system and the method which can purify the hydrofluoric acid-containing wastewater to enable the hydrofluoric acid-containing wastewater to reach the discharge standard and can recycle hydrofluoric acid have important significance.
Disclosure of Invention
The invention mainly aims to provide a system and a method for treating hydrofluoric acid-containing wastewater, which aim to solve the problems of large discharge amount of hydrofluoric acid-containing wastewater and low hydrofluoric acid recovery rate in the prior art.
In order to achieve the above object, an aspect of the present invention provides a system for treating hydrofluoric acid-containing wastewater, including: a solid-liquid separation device, a membrane distillation unit, an ultrafiltration device and a reverse osmosis unit. The solid-liquid separation device is provided with a hydrofluoric acid-containing wastewater feed inlet, a liquid phase outlet and a slurry outlet; the membrane distillation unit is provided with a feed liquid inlet and an enriched liquid outlet, and the feed liquid inlet is communicated with the liquid phase outlet through a liquid phase conveying pipeline; the ultrafiltration device is provided with an enrichment liquid inlet, a concentration liquid outlet and a filtered water outlet, and the enrichment liquid inlet is communicated with the enrichment liquid outlet through an enrichment liquid conveying pipeline; the reverse osmosis unit is provided with a concentrated solution inlet, a hydrofluoric acid outlet and a reverse osmosis residual liquid outlet, and the concentrated solution inlet is communicated with the concentrated solution outlet through a concentrated solution conveying pipeline.
Further, the membrane distillation unit comprises: a heating device and a condensing device; the heating device is provided with a cavity and a microporous membrane arranged in the cavity, the cavity is divided into a heating area and a gas phase area by the microporous membrane, the heating area is provided with a feeding liquid inlet and a residual steaming liquid outlet, and the gas phase area is provided with a steam outlet; the condensing device is provided with a steam inlet and an enriched liquid outlet, and the steam inlet is communicated with the steam outlet through a steam conveying pipeline.
Further, the reverse osmosis unit comprises: a first reverse osmosis unit and a second reverse osmosis unit. The first reverse osmosis device is provided with a concentrated solution inlet, a hydrofluoric acid outlet and a first recovered water outlet; the second reverse osmosis device is provided with a first recovered water inlet, a filtered water inlet and a second recovered water outlet, the first recovered water inlet is communicated with the first recovered water outlet through a recovered water conveying pipeline, and the filtered water inlet is communicated with the filtered water outlet through a filtered water conveying pipeline.
Further, the system for treating hydrofluoric acid-containing wastewater further comprises: a water quality adjusting unit, a coagulating sedimentation unit and a pH adjusting device. The water quality adjusting unit is provided with a water quality adjusting inlet and a mixture outlet, and the water quality adjusting inlet is respectively communicated with the residual steaming liquid outlet and the reverse osmosis liquid outlet through a residual liquid conveying pipeline; the coagulating sedimentation unit is provided with a material inlet to be coagulated, an auxiliary agent inlet, a supernatant outlet and a first solid phase outlet, and the material inlet to be coagulated is communicated with the mixture outlet through a mixture conveying pipeline; the pH adjusting device is provided with a material inlet to be adjusted in pH and a fluorine-containing waste liquid outlet, and the material inlet to be adjusted in pH is communicated with the supernatant outlet through a supernatant conveying pipeline.
Further, the water quality adjusting unit includes: compounding device and air-blast device. The mixing device is provided with a water quality adjusting inlet, a blast port and a mixture outlet; the air blowing device is provided with an air outlet which is communicated with the blast port.
Further, the coagulating sedimentation unit comprises: a coagulating sedimentation device and an auxiliary agent supply device. The coagulating sedimentation unit is provided with a material inlet to be coagulated, a supernatant outlet, a first solid phase outlet and an auxiliary agent inlet; the auxiliary agent supply device is provided with an auxiliary agent supply port which is communicated with the auxiliary agent inlet and used for supplying flocculating agent and precipitating agent to the coagulating sedimentation device.
Further, the system for treating hydrofluoric acid-containing wastewater further comprises: a solid-phase sludge storage device and a filter pressing device. The solid-phase sludge storage device is provided with a sludge inlet and a sludge outlet, and the sludge inlet is respectively communicated with the slurry outlet and the first solid-phase outlet through a solid-phase sludge conveying pipeline; the filter pressing device is provided with a second solid phase inlet, a filter pressing liquid outlet and a second solid phase outlet, and the sludge outlet and the second solid phase inlet are communicated with the filter pressing liquid outlet and the water quality adjusting inlet through a filter pressing liquid conveying pipeline.
In order to achieve the above object, another aspect of the present invention further provides a method for treating hydrofluoric acid-containing wastewater, the method comprising: carrying out solid-liquid separation treatment on hydrofluoric acid-containing wastewater to obtain a liquid-phase product and a first solid-phase product; performing membrane distillation treatment on the liquid-phase product to obtain an enrichment solution; carrying out ultrafiltration treatment on the enriched liquid to obtain fluorine-containing ion concentrated liquid and filtered water; and carrying out reverse osmosis treatment on the fluorine-containing ion concentrated solution and the filtered water to obtain hydrofluoric acid.
Further, the membrane distillation treatment process comprises the following steps: heating the liquid-phase product to obtain a heating liquid; heating liquid is treated by a microporous membrane and cooled to obtain enrichment liquid; preferably, the temperature of the heating liquid is 30-60 ℃, and the temperature of the enrichment liquid is 5-15 ℃; more preferably, the microporous membrane is selected from polyvinylidene fluoride and/or polytetrafluoroethylene.
Furthermore, the ultrafiltration treatment process is carried out by adopting an ultrafiltration membrane, and the ultrafiltration membrane is selected from polyvinylidene fluoride and/or polytetrafluoroethylene.
Further, the method for treating the hydrofluoric acid-containing wastewater further comprises the following steps: mixing the hot residual liquid obtained by membrane distillation with the reverse osmosis residual liquid obtained by reverse osmosis treatment, and adjusting the water quality to obtain a material to be subjected to coagulation treatment; adding a coagulant into the material to be subjected to coagulation treatment, and performing coagulation sedimentation treatment to obtain a supernatant and fluorine-containing solid-phase waste residues; regulating the pH of the supernatant to obtain fluorine-containing waste liquid meeting the discharge standard; preferably, the coagulant comprises a precipitant and a flocculant; preferably, the weight ratio of the material to be coagulated, the precipitator and the flocculating agent is 100 (210-250) to (1-30); preferably, the pH value of the coagulating sedimentation treatment is 10-12.
By applying the technical scheme of the invention, on one hand, the hydrofluoric acid can be recovered, and the recovery rate of the hydrofluoric acid is greatly improved; on the other hand, the content of fluorinion in the hydrofluoric acid-containing waste liquid can be reduced, which is beneficial to improving water quality and reducing the harm to the environment; in addition, the system for treating the hydrofluoric acid-containing waste liquid has a compact design, can shorten the cycle of recovering hydrofluoric acid, and is beneficial to improving the renewable value of hydrofluoric acid.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a schematic view showing a configuration of a hydrofluoric acid-containing wastewater treatment system according to example 1 of the present invention.
Wherein the figures include the following reference numerals:
100. a solid-liquid separation device; 101. a feed inlet for hydrofluoric acid-containing wastewater; 102. a liquid phase outlet; 103. a slurry outlet;
200. a membrane distillation unit; 210. a heating device; 220. a condensing unit; 211. a feed liquid inlet; 212. a raffinate outlet; 221. a steam inlet; 222. an outlet for the enrichment liquid;
300. an ultrafiltration device; 301. an enrichment liquid inlet; 302. a concentrated solution outlet; 303. a filtered water outlet;
400. a reverse osmosis unit; 410. a first reverse osmosis unit; 420. a second reverse osmosis unit; 411. a concentrated solution inlet; 412. a hydrofluoric acid outlet; 413. a first recovered water outlet; 421. a first recovered water inlet; 422. a filtered water inlet; 423. a second recovered water outlet; 424. a reverse osmosis raffinate outlet;
500. a water quality adjusting unit; 510. a mixing device; 520. a blower device; 511. a water quality adjusting inlet; 512. a tuyere; 513. a mixture outlet; 521. an air outlet;
600. a coagulating sedimentation unit; 610. a coagulating sedimentation device; 620. an auxiliary agent supply device; 611. a material inlet to be subjected to coagulation treatment; 612. an additive inlet; 613. a supernatant outlet; 614. a first solid phase outlet; 621. an auxiliary agent supply port;
700. a pH adjusting device; 701. a material inlet for adjusting pH; 702. a fluorine-containing waste liquid outlet;
800. a solid phase sludge storage device; 801. a sludge inlet; 802. a sludge outlet;
900. a filter pressing device; 901. a second solid phase inlet; 902. a filtrate outlet; 903. and a second solid phase outlet.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.
As described in the background art, the existing treatment system for hydrofluoric acid-containing wastewater has the problems of large discharge amount of fluorine-containing waste liquid and low hydrofluoric acid recovery rate. In order to solve the above technical problem, the present application provides a system for treating hydrofluoric acid-containing wastewater, comprising: a solid-liquid separation device 100, a membrane distillation unit 200, an ultrafiltration device 300 and a reverse osmosis unit 400. The solid-liquid separation device 100 is provided with a hydrofluoric acid-containing wastewater feed inlet 101, a liquid phase outlet 102 and a slurry outlet 103; the membrane distillation unit 200 is provided with a feed liquid inlet 211 and a rich liquid outlet 222, and the feed liquid inlet 211 is communicated with the liquid phase outlet 102 through a liquid phase conveying pipeline; the ultrafiltration device 300 is provided with an enrichment liquid inlet 301, a concentration liquid outlet 302 and a filtered water outlet 303, wherein the enrichment liquid inlet 301 is communicated with the enrichment liquid outlet 222 through an enrichment liquid conveying pipeline; the reverse osmosis unit 400 is provided with a concentrate inlet 411, a hydrofluoric acid outlet 412 and a reverse osmosis raffinate outlet 424, and the concentrate inlet 411 is communicated with the concentrate outlet 302 through a concentrate delivery line.
The hydrofluoric acid-containing wastewater contains a large amount of hydrofluoric acid (HF) and fluoride ions (F)-) And solid phase suspensions. After the hydrofluoric acid-containing wastewater is separated by the solid-liquid separation device 100, hydrofluoric acid and fluorine ions enter a liquid phase, so that the risk that suspended matters block a membrane separation channel in the membrane distillation process can be reduced, and the subsequent membrane distillation treatment is facilitated; the solid phase suspension exists in the form of solid phase product or solid-liquid mixture. The liquid phase product obtained in the above step enters a membrane distillation unit 200, and HF in the liquid phase can be separated out in a distillation manner, so as to obtain an enriched liquid containing hydrofluoric acid. Then the enrichment solution containing hydrofluoric acid is further processed in an ultrafiltration systemSeparating to obtain liquid phase product containing hydrofluoric acid with higher concentration, namely concentrated solution containing hydrofluoric acid. In order to remove water in the concentrated solution, hydrofluoric acid is recovered, and finally the concentrated solution is subjected to reverse osmosis treatment.
By adopting the treatment system for the hydrofluoric acid-containing wastewater, on one hand, the hydrofluoric acid can be recovered, and the recovery rate of the hydrofluoric acid is greatly improved; on the other hand, the content of fluorinion in the hydrofluoric acid-containing wastewater can be reduced, which is beneficial to improving water quality and reducing harm to the environment; in addition, the treatment system for the hydrofluoric acid-containing wastewater is compact in design, can shorten the recovery treatment period of hydrofluoric acid, and is beneficial to improving the renewable utilization value of hydrofluoric acid.
In a preferred embodiment, the membrane distillation unit 200 comprises: a heating device 210 and a condensing device 220. The heating device 210 is provided with a cavity and a microporous membrane arranged in the cavity, the cavity is divided into a heating zone and a gas phase zone by the microporous membrane, the heating zone is provided with a feeding liquid inlet 211 and a raffinate steaming outlet 212, and the gas phase zone is provided with a steam outlet. The condensing device 220 is provided with a steam inlet 221 and an enriched liquid outlet 222, and the steam inlet 221 is communicated with the steam outlet through a steam conveying pipeline. A liquid phase product obtained after the hydrofluoric acid-containing wastewater is treated by the solid-liquid separation device 100 is heated in the heating device 210 to form hot vapor containing HF; this portion of the hot vapor can pass through the microporous membrane and then be cooled to a concentrated liquid in a condensing unit 220. Wherein the microporous membrane is a porous membrane having a pore size of 10nm to 0.35. mu.m. The primary enrichment of hydrofluoric acid is realized through the process. The process has the advantages of simple operation, low cost, high enrichment rate and the like, so the step is favorable for improving the recovery rate of the hydrofluoric acid obtained subsequently.
Reverse osmosis is a membrane separation operation that uses pressure as a driving force to separate a solvent from a solution. After reverse osmosis treatment, a concentrated solution can be obtained at the high pressure side and a permeated solvent can be obtained at the low pressure side. Thus, the reverse osmosis unit 400 can be used to separate fluorine ions from the solvent water in the hydrofluoric acid-containing wastewater. In a preferred embodiment, the reverse osmosis unit 400 comprises: a first reverse osmosis unit 410 and a second reverse osmosis unit 420. The first reverse osmosis device 410 is provided with a concentrated solution inlet 411, a hydrofluoric acid outlet 412 and a first recovered water outlet 413; the second reverse osmosis device 420 is provided with a first recovered water inlet 421, a filtered water inlet 422, and a second recovered water outlet 423, the first recovered water inlet 421 and the first recovered water outlet 413 are communicated through a recovered water delivery line, and the filtered water inlet 422 and the filtered water outlet 303 are communicated through a filtered water delivery line. Compared with a single reverse osmosis device, the two reverse osmosis devices communicated with each other are adopted, so that not only can hydrofluoric acid be recycled, but also water can be recycled.
The residual hydrofluoric acid and the fluorine ions are contained in the distilled residual liquid, and the residual hydrofluoric acid and the fluorine ions are subjected to subsequent treatment to enable the fluorine-containing waste liquid to reach the discharge standard. In a preferred embodiment, the system for treating hydrofluoric acid-containing wastewater further comprises: a water quality adjusting unit 500, a coagulating sedimentation unit 600 and a pH adjusting device 700. The water quality adjusting unit 500 is provided with a water quality adjusting inlet 511 and a mixture outlet 513, wherein the water quality adjusting inlet 511 is respectively communicated with the distilled residual liquid outlet 212 and the reverse osmosis residual liquid outlet 424 through residual liquid conveying pipelines; the coagulating sedimentation unit 600 is provided with a material inlet 611 to be coagulated, an auxiliary agent inlet 612, a supernatant outlet 613 and a first solid phase outlet 614, wherein the material inlet 611 to be coagulated is communicated with the mixture outlet 513 through a mixture conveying pipeline; the pH adjusting device 700 is provided with a material inlet 701 for adjusting pH and a fluorine-containing waste liquid outlet 702, and the material inlet 701 for adjusting pH is communicated with a supernatant outlet 613 through a supernatant conveying pipeline.
The water quality adjusting unit 500 is adopted to mix the distilled residual liquid and the reverse osmosis residual liquid, and soluble substances and water can form supernatant through coagulation treatment, and residual fluorine ions of the distilled residual liquid and the reverse osmosis residual liquid are precipitated to form solid-phase precipitate. The method is favorable for reducing the concentration of fluorine ions in the distilled residual liquid and the reverse osmosis residual liquid, further favorable for forming fluorine-containing waste liquid meeting the discharge standard after subsequent pH adjustment, and favorable for reducing the pollution to the environment.
When a coagulant containing calcium ions is added in the coagulating sedimentation treatment process, the fluorine ions and the calcium ions are combined to form calcium fluoride precipitate, so that the calcium fluoride precipitate is settled at the bottom of the coagulating sedimentation device 610 and is convenient to separate from supernatant.
In a preferred embodiment, the water quality adjusting unit 500 includes: a mixing device 510 and a blowing device 520. The mixing device 510 is provided with a water quality adjusting inlet 511, a blast port 512 and a mixture outlet 513; the air blowing device 520 is provided with an air outlet 521, and the air outlet 521 communicates with the blower port 512. Adopt air-blast device 520 to mix the stirring, be favorable to improving the mixing uniformity of material among the compounding device 510 to be favorable to improving the reaction degree of precipitation reaction or flocculation reaction among the follow-up coagulating sedimentation device 610, thereby be favorable to further reducing the concentration of fluorine ion in the fluorine-containing waste liquid, and then reduce the pollution to the environment.
In a preferred embodiment, the coagulating sedimentation unit 600 comprises: a coagulating sedimentation device 610 and an auxiliary agent supply device 620. The coagulating sedimentation unit 600 is provided with a material inlet 611 to be coagulated, a supernatant outlet 613, a first solid phase outlet 614 and an auxiliary agent inlet 612; the auxiliary agent supply device 620 is provided with an auxiliary agent supply port 621, and the auxiliary agent supply port 621 is communicated with the auxiliary agent inlet 612 and used for supplying a flocculating agent and a precipitating agent to the coagulating sedimentation device 610.
Adding a precipitator and a flocculating agent by adopting the auxiliary agent supply device 620 to enable the precipitator and the materials in the coagulating sedimentation device 610 to have a precipitation reaction to obtain a precipitation product; and flocculating the precipitate by using a flocculating agent to facilitate subsequent removal.
In order to make the effect of the coagulating sedimentation treatment more obvious, in an alternative embodiment, the coagulating sedimentation device 610 comprises a first coagulating sedimentation tank and a second coagulating sedimentation tank which are sequentially communicated.
In a preferred embodiment, the system for treating hydrofluoric acid-containing wastewater further comprises: a solid-phase sludge storage device 800 and a filter pressing device 900. The solid-phase sludge storage device 800 is provided with a sludge inlet 801 and a sludge outlet 802, wherein the sludge inlet 801 is respectively communicated with the slurry outlet 103 and the first solid-phase outlet 614 through a solid-phase sludge conveying pipeline; the filter pressing device 900 is provided with a second solid phase inlet 901, a filter pressing liquid outlet 902 and a second solid phase outlet 903, wherein the sludge outlet 802 and the second solid phase inlet 901 are communicated with the filter pressing liquid outlet 902 and the water quality adjusting inlet 511 through a filter pressing liquid conveying pipeline through a solid phase sludge conveying pipeline. The solid-phase sludge storage apparatus 800 is used to temporarily store solid-phase waste. The solid-phase waste residue can be used for treating a small amount of residual liquid phase in the temporarily stored solid-phase waste residue after passing through the filter pressing device 900 to obtain filter pressing liquid, and the filter pressing liquid enters the water quality adjusting unit 500 through the water quality adjusting inlet 511 to participate in water quality adjustment.
The second aspect of the present application also provides a method for treating hydrofluoric acid-containing wastewater, which includes: carrying out solid-liquid separation treatment on hydrofluoric acid-containing wastewater to obtain a liquid-phase product and a first solid-phase product; performing membrane distillation treatment on the liquid-phase product to obtain an enrichment solution; carrying out ultrafiltration treatment on the enriched liquid to obtain fluorine-containing ion concentrated liquid and filtered water; and carrying out reverse osmosis treatment on the fluorine-containing ion concentrated solution and the filtered water to obtain hydrofluoric acid.
The hydrofluoric acid-containing wastewater contains a large amount of hydrofluoric acid, fluoride ions and solid suspended substances. After the hydrofluoric acid-containing wastewater is subjected to solid-liquid separation treatment, hydrofluoric acid and fluoride ions enter a liquid phase, so that subsequent membrane distillation treatment is facilitated; the solid phase suspension exists in the form of solid phase product or solid-liquid mixture. And (3) performing membrane distillation treatment on the obtained liquid phase product, and separating HF in the liquid phase in a distillation mode to obtain enriched liquid containing hydrofluoric acid. And further separating the enriched liquid containing hydrofluoric acid to obtain a liquid phase product containing hydrofluoric acid with higher concentration, namely obtaining a concentrated liquid containing hydrofluoric acid. Recovering hydrofluoric acid to remove water in the concentrated solution, and performing reverse osmosis treatment on the concentrated solution.
By adopting the method, on one hand, the hydrofluoric acid can be recovered, and the recovery rate of the hydrofluoric acid is greatly improved; on the other hand, the content of fluorinion in the hydrofluoric acid-containing wastewater can be reduced, which is beneficial to improving water quality and reducing harm to the environment; in addition, the method is simple to operate, can shorten the recovery treatment period of the hydrofluoric acid, and is beneficial to improving the renewable value of the hydrofluoric acid.
In a preferred embodiment, the membrane distillation process comprises: heating the liquid-phase product to obtain a heating liquid; and (4) treating the heating liquid by a microporous membrane and cooling to obtain an enrichment liquid.
Heating a liquid-phase product obtained after the hydrofluoric acid-containing wastewater is subjected to solid-liquid separation treatment to form hot vapor containing HF; this portion of the hot vapor is able to pass through a microporous membrane (a porous membrane having a pore size of 10nm to 0.35 μm) and then cooled to a concentrated solution. The primary enrichment of hydrofluoric acid is realized through the process. The process has the advantages of simple operation, low cost, high enrichment rate and the like, so the step is favorable for improving the recovery rate of the hydrofluoric acid obtained subsequently.
In order to further improve the recovery rate of the fluoride ions and the hydrofluoric acid, preferably, the temperature of the heating liquid is 30-60 ℃, and the temperature of the enrichment liquid is 5-15 ℃. In order to select a microporous membrane more suitable for resisting the corrosion of hydrofluoric acid, the service life of the microporous membrane is prolonged; meanwhile, in order to further improve the recovery rate of hydrofluoric acid and prolong the service life of the microporous membrane, more preferably, the microporous membrane comprises but is not limited to polyvinylidene fluoride and/or polytetrafluoroethylene.
An ultrafiltration membrane is a polymeric semipermeable membrane used to separate polymeric colloids or suspended particles of a certain size from a solution. The ultrafiltration membrane is adopted for ultrafiltration treatment, so that impurity ions in the enriched liquid can be further removed; in the process, fluorine ions and water are separated to obtain filtered water, so that the subsequent further recovery of water is facilitated, the recovery rate of hydrofluoric acid is improved, and meanwhile, the recovered water can be obtained, and the economic benefit is further improved. In a preferred embodiment, the ultrafiltration treatment is performed using an ultrafiltration membrane, including but not limited to polyvinylidene fluoride and/or polytetrafluoroethylene. Compared with other types, the ultrafiltration membrane has better chemical corrosion resistance, is beneficial to reducing the treatment load of a subsequent reverse osmosis membrane, and is beneficial to improving the recovery rate of hydrofluoric acid.
In a preferred embodiment, the method for treating hydrofluoric acid-containing wastewater further comprises: mixing hot residual liquid obtained by membrane distillation, filtrate and reverse osmosis residual liquid obtained by reverse osmosis treatment, and adjusting water quality to obtain a material to be subjected to coagulation treatment; adding a coagulant into the material to be subjected to coagulation treatment, and performing coagulation sedimentation treatment to obtain a supernatant and fluorine-containing solid-phase waste residues; and (4) carrying out pH adjustment on the supernatant to obtain the fluorine-containing waste liquid meeting the discharge standard. Mixing the residual steaming liquid and the residual reverse osmosis liquid, and performing coagulation treatment to precipitate residual fluorine ions in the residual steaming liquid and the residual reverse osmosis liquid to form solid-phase precipitate. The method is favorable for reducing the concentration of fluorine ions in the distilled residual liquid and the reverse osmosis residual liquid, so that the fluorine-containing waste liquid meeting the discharge standard is formed after the subsequent pH adjustment, and the environmental pollution is favorably reduced.
In a preferred embodiment, the coagulant includes, but is not limited to, a precipitant and a flocculant. More preferably, the above-mentioned precipitating agents include, but are not limited to, calcium hydroxide and/or calcium chloride; flocculants include, but are not limited to, polyaluminum chloride and/or polyacrylamide.
When the precipitator is calcium hydroxide or calcium chloride, fluoride ions are combined with calcium ions to form calcium fluoride precipitate, namely the following chemical reaction occurs: ca2++F-→CaF2↓. When polyaluminium chloride (PAC) is used as a flocculating agent, the polyaluminium chloride can adsorb suspended matters in a reaction system after being hydrolyzed in water and enables the suspended matters to be settled, so that the polyaluminium chloride is convenient to remove. Compared with other precipitating agents and flocculating agents, the adoption of the auxiliary agents is beneficial to further improving the removal effect and the removal efficiency of the fluoride ions. In order to further improve the removal rate of fluorine ions, the weight ratio of the material to be subjected to coagulation treatment, the precipitator and the coagulant is preferably 100 (210-250) to (1-30).
In a preferred embodiment, the pH value of the coagulating sedimentation treatment is 10-12. Compared with other ranges, the pH value is limited in the range, so that the reaction degree of coagulating sedimentation treatment can be improved, fluoride ions can be removed more completely, the content of the fluoride ions in the hydrofluoric acid-containing wastewater is reduced, the discharge standard is reached, and the harm to the environment is reduced.
The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.
It is to be noted that the present application is entirely in effectThe water quality pH values of the inlet water and the outlet water obtained after treatment required by the examples and the comparative examples are measured by a GB/T6920 glass electrode method, the suspended matters are measured by a GB/T11901 gravimetric method, and the Chemical Oxygen Demand (COD)Cr) The determination of (A) is carried out by an HJ 828 potassium dichromate method, and the determination of fluoride is carried out by a GB/T7484 ion selective electrode method.
Example 1
The daily water yield of silicon rod cleaning wastewater (namely hydrofluoric acid-containing wastewater or influent water) of a certain monocrystalline silicon plant is 200m3And d. The silicon rod cleaning wastewater is treated by using the system for treating the hydrofluoric acid-containing wastewater shown in fig. 1, so as to obtain a fluorine-containing waste liquid (effluent) meeting the discharge standard, wherein the water quality parameters of the silicon rod cleaning wastewater are shown in table 1.
TABLE 1
Water quality parameter COD(mg/L) SS(mg/L) F-(mg/L) pH
Silicon rod cleaning wastewater (influent) 108 500 3000 0.8
After the silicon rod cleaning wastewater is separated by a filter (the lining material of the filter is fluorine-resistant FRP), the SS of the effluent is reduced to 20mg/L, hydrofluoric acid and fluorine ions enter a liquid phase, the residual fluorine-containing sludge enters a fluorine-containing sludge tank, filter pressing is carried out by a plate-and-frame filter press to obtain a filter pressing liquid and a mud cake, the filter pressing liquid participates in water quality regulation, and the mud cake can be transported outside for treatment.
Introducing the liquid phase product into a membrane distillation unit 200 for membrane distillation treatment to obtain an enriched liquid, wherein the membrane distillation flux is 20L/(m)2H). The liquid phase product is first heated to form 50 deg.c heating liquid and HF containing hot steam, and the hot steam is then made to pass through hydrophobic porous PTFE membrane with pore size of 0.22 micron to form 10 deg.c concentrated liquid via condensation. And the distilled residual liquid enters the water quality adjusting unit 500 for water quality adjustment.
Performing ultrafiltration treatment on the concentrated solution by using an ultrafiltration device 300, wherein the operating pressure is controlled to be about 0.4MPa, and the flux is 40L/(m)2H) the ultrafiltration membrane is a polytetrafluoroethylene membrane (Sumitomo Electric Industries, Ltd. model POREFLON)TMMemberane), and after ultrafiltration treatment, respectively obtaining fluorine-containing ion concentrated solution and filtered water.
Setting the operating pressure of the first reverse osmosis device 410 to be 0.8MPa, and introducing the fluorine-containing ion concentrated solution obtained after ultrafiltration into the first reverse osmosis device 410 for reverse osmosis treatment to obtain 4% hydrofluoric acid; setting the operation pressure of the second reverse osmosis device 420 at 1.3MPa, and introducing the filtered water obtained after ultrafiltration into the second reverse osmosis device 420 for reverse osmosis treatment to obtain first recovered water with pure water yield of 38m3And d. The reverse osmosis residual liquid is introduced into the water quality adjusting unit 500, and the water quality is adjusted together with the above-mentioned evaporation residual liquid.
In the water quality adjusting process, air stirring is carried out on the materials to be subjected to coagulation treatment (comprising the residual steaming liquid, the reverse osmosis residual liquid and the pressure filtrate) by adopting an air blower, wherein the air flow of the air blower is 0.3m3Min, adding 300mg/L of calcium hydroxide into the primary coagulation sedimentation tank to adjust the pH value to 10, transferring the materials in the primary coagulation sedimentation tank into a secondary coagulation sedimentation tank, and respectively adding 50mg/L of calcium chloride, 20mg/L of polyaluminium chloride (PAC) and 2.0 of Polyacrylamide (PAM)mg/L (the weight ratio of the material to be coagulated, the precipitator and the flocculating agent is 150:350:22) to obtain supernatant and fluorine-containing solid-phase waste residue (the yield is 153 m)3And/d). Transferring the part of fluorine-containing solid-phase waste residue into a fluorine-containing sludge tank, and performing filter pressing treatment on the fluorine-containing solid-phase waste residue and the residual fluorine-containing sludge after filtration by a plate-and-frame filter press. And (3) adding acid into the obtained supernatant to adjust the pH to 7.2 by adopting a pH adjusting device 700, so as to obtain the fluorine-containing waste liquid meeting the discharge standard.
After the treatment system and the treatment method for the hydrofluoric acid-containing wastewater are adopted for treatment, the yield of 4% hydrofluoric acid is 12m3D; the yield of pure water was 38m3D; the yield of the fluorine-containing sludge is 2m (the water content is 60 percent)3And d. The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Example 2
The difference from example 1 is that: the temperature of the heating liquid is 30 ℃, and the temperature of the enrichment liquid is 15 ℃.
The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Example 3
The difference from example 1 is that: the temperature of the heating liquid is 60 ℃, and the temperature of the enrichment liquid is 5 ℃.
The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Example 4
The difference from example 1 is that: the temperature of the heating liquid is 80 ℃, and the temperature of the enrichment liquid is 25 ℃.
The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Example 5
The difference from example 1 is that: the microporous membrane used in the membrane distillation process was a polytetrafluoroethylene porous membrane (Donaldson, manufacturer) with a pore size of 0.22 μm.
The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Example 6
The difference from example 1 is that: the microporous membrane used in the membrane distillation process is polyvinylidene fluoride porous membrane (manufacturer, Hangzhou family Baite), and its pore diameter is 0.45 μm.
The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Example 7
The difference from example 1 is that: the ultrafiltration membrane is a polyvinylidene fluoride membrane (manufacturer's ju-dao).
The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Example 8
The difference from example 1 is that: the ultrafiltration membrane was Polyethersulfone (PES) (meborry biofilm technology ltd, manufactures).
The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Example 9
The difference from example 1 is that: the material to be coagulated Ca (OH)2And CaCl2PAC and PAM were in a weight ratio of 100:210: 30.
The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Example 10
The difference from example 1 is that: the material to be coagulated Ca (OH)2And CaCl2The weight ratio of PAC to PAM was 100:250: 1.
The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Example 11
The difference from example 1 is that: the material to be coagulated Ca (OH)2And CaCl2The weight ratio of PAC to PAM was 100:150: 0.5.
The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Example 12
The difference from example 1 is that: adding calcium hydroxide to adjust the pH value to 12.
The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Example 13
The difference from example 1 is that: adding calcium hydroxide to adjust the pH value to 9.
The water quality parameters of the fluorine-containing waste liquid (effluent) meeting the discharge standard are shown in Table 2.
Comparative example 1
The difference from example 1 is that: the membrane distillation unit 200 is not included in the system for treating hydrofluoric acid-containing wastewater.
The water quality parameters of the obtained fluorine-containing waste liquid are shown in Table 3.
Comparative example 2
The difference from example 1 is that: the system for treating hydrofluoric acid-containing wastewater does not include the ultrafiltration device 300.
The water quality parameters of the obtained fluorine-containing waste liquid are shown in Table 3.
Comparative example 3
The difference from example 1 is that: the reverse osmosis unit 400 is not included in the system for treating hydrofluoric acid-containing wastewater.
The water quality parameters of the obtained fluorine-containing waste liquid are shown in Table 3.
TABLE 2
Examples COD(mg/L) SS(mg/L) F-(mg/L) pH
1 95 18 10 7.2
2 90 15 9 7.5
3 96 17 10 7.2
4 98 18 12 7.3
5 99 20 11 7.3
6 100 20 12 7.5
7 94 17 12 7.3
8 99 18 12 7.3
9 99 17 15 7.8
10 90 15 8 7.5
11 99 19 17 7.4
12 93 20 10 7.8
13 99 20 14 6.8
TABLE 3
Comparative example COD(mg/L) SS(mg/L) F-(mg/L) pH
1 101 25 20 7.5
2 102 21 20 7.8
3 105 21 20 7.4
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:
as is clear from comparative examples 1 to 4, the temperatures of the heating liquid and the concentrated liquid are respectively limited to the preferable ranges in the present application as compared with other temperature ranges, which is advantageous for further improving the recovery rates of the fluorine ions and the hydrofluoric acid.
Comparing examples 1, 5 and 6, it is seen that limiting the pore size of the microporous membrane to the preferred range of the present application is advantageous to further increase the recovery rate of hydrofluoric acid and extend the service life of the microporous membrane, as compared to other pore size ranges.
Comparing examples 1, 7 and 8, it can be seen that the preferred type of ultrafiltration membrane of the present application has better chemical resistance than other types, and is also advantageous in reducing the treatment load of the subsequent reverse osmosis membrane and in increasing the recovery rate of hydrofluoric acid.
Comparing examples 1 and 9 to 11, it is understood that the weight ratio of the material to be coagulated, the precipitant and the coagulant includes but is not limited to the preferable range of the present application, and the removal rate of the fluoride ion can be further improved by limiting the weight ratio to the material to be coagulated, the precipitant and the coagulant within the preferable range of the present application.
Comparing examples 1, 12 and 13, it can be seen that limiting the pH value within the preferred range of the present application can improve the reaction degree of the coagulation precipitation treatment, so that the removal of the fluoride ions is more complete, and further, the content of the fluoride ions in the fluoride-containing wastewater is reduced, thereby achieving the emission standard and reducing the harm to the environment.
Comparing examples 1 to 13 and comparative examples 1 to 3, it can be seen that, on one hand, the recovery of hydrofluoric acid can be realized and the recovery rate of hydrofluoric acid is greatly improved by applying the technical scheme of the present application; on the other hand, the content of fluorine ions in the fluorine-containing wastewater can be reduced, which is beneficial to improving the water quality and reducing the harm to the environment; in addition, the system for treating hydrofluoric acid-containing wastewater is compact in design, can shorten the cycle of hydrofluoric acid recovery and treatment, and is beneficial to improving the renewable value of hydrofluoric acid.
It is noted that the terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances such that the embodiments of the application described herein are, for example, capable of operation in sequences other than those described or illustrated herein.
The above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (11)

1. A system for treating hydrofluoric acid-containing wastewater, comprising:
the device comprises a solid-liquid separation device (100), wherein the solid-liquid separation device (100) is provided with a hydrofluoric acid-containing wastewater inlet (101), a liquid phase outlet (102) and a slurry outlet (103);
a membrane distillation unit (200), wherein the membrane distillation unit (200) is provided with a feed liquid inlet (211) and a concentrated liquid outlet (222), and the feed liquid inlet (211) is communicated with the liquid phase outlet (102) through a liquid phase conveying pipeline;
the device comprises an ultrafiltration device (300), wherein the ultrafiltration device (300) is provided with an enrichment liquid inlet (301), a concentrated liquid outlet (302) and a filtered water outlet (303), and the enrichment liquid inlet (301) is communicated with the enrichment liquid outlet (222) through an enrichment liquid conveying pipeline;
the reverse osmosis unit (400), reverse osmosis unit (400) is provided with concentrate entry (411), hydrofluoric acid export (412) and reverse osmosis raffinate export (424), concentrate entry (411) with concentrate export (302) are through concentrate conveying line intercommunication.
2. The system for treating hydrofluoric acid-containing wastewater according to claim 1, wherein the membrane distillation unit (200) comprises:
the heating device (210) is provided with a cavity and a microporous membrane arranged in the cavity, the cavity is divided into a heating area and a gas phase area through the microporous membrane, the heating area is provided with a feeding liquid inlet (211) and a raffinate outlet (212), and the gas phase area is provided with a steam outlet;
the condensation device (220) is provided with a steam inlet (221) and the enriched liquid outlet (222), and the steam inlet (221) is communicated with the steam outlet through a steam conveying pipeline.
3. The system for treating hydrofluoric acid containing wastewater according to claim 1 or 2, wherein the reverse osmosis unit (400) comprises:
a first reverse osmosis device (410), the first reverse osmosis device (410) being provided with a concentrate inlet (411), a hydrofluoric acid outlet (412) and a first recovered water outlet (413);
a second reverse osmosis device (420), the second reverse osmosis device (420) being provided with a first recovered water inlet (421), a filtered water inlet (422) and a second recovered water outlet (423), the first recovered water inlet (421) being in communication with the first recovered water outlet (413) through a recovered water delivery line, the filtered water inlet (422) being in communication with the filtered water outlet (303) through a filtered water delivery line.
4. The system for treating hydrofluoric acid containing wastewater according to claim 2, further comprising:
the water quality adjusting unit (500) is provided with a water quality adjusting inlet (511) and a mixture outlet (513), and the water quality adjusting inlet (511) is respectively communicated with the residual steaming liquid outlet (212) and the reverse osmosis residual liquid outlet (424) through a residual liquid conveying pipeline;
the coagulating sedimentation unit (600), the coagulating sedimentation unit (600) is provided with a material inlet (611) to be coagulated, an auxiliary agent inlet (612), a supernatant outlet (613) and a first solid phase outlet (614), and the material inlet (611) to be coagulated is communicated with the mixture outlet (513) through a mixture conveying pipeline;
the device comprises a pH adjusting device (700), wherein the pH adjusting device (700) is provided with a material inlet (701) to be adjusted in pH and a fluorine-containing waste liquid outlet (702), and the material inlet (701) to be adjusted in pH is communicated with the supernatant outlet (613) through a supernatant conveying pipeline.
5. The system for treating hydrofluoric acid-containing wastewater according to claim 4, wherein the water quality adjusting unit (500) comprises:
the mixing device (510), the mixing device (510) is provided with the water quality adjusting inlet (511), the blast port (512) and the mixed material outlet (513);
a blower device (520), the blower device (520) being provided with an air outlet (521), the air outlet (521) being in communication with the blower port (512).
6. The system for treating hydrofluoric acid-containing wastewater according to claim 4, wherein the coagulation sedimentation unit (600) comprises:
a coagulating sedimentation device (610), wherein the coagulating sedimentation unit (600) is provided with the material inlet (611) to be coagulated, the supernatant outlet (613), the first solid phase outlet (614) and the auxiliary agent inlet (612);
the auxiliary agent supply device (620), the auxiliary agent supply device (620) is provided with an auxiliary agent supply port (621), and the auxiliary agent supply port (621) is communicated with the auxiliary agent inlet (612) and is used for supplying flocculating agent and precipitating agent to the coagulating sedimentation device (610).
7. The system for treating hydrofluoric acid containing wastewater according to claim 5 or 6, further comprising:
the solid-phase sludge storage device (800), the solid-phase sludge storage device (800) is provided with a sludge inlet (801) and a sludge outlet (802), and the sludge inlet (801) is respectively communicated with the slurry outlet (103) and the first solid-phase outlet (614) through a solid-phase sludge conveying pipeline;
the filter pressing device (900) is provided with a second solid phase inlet (901), a filter pressing liquid outlet (902) and a second solid phase outlet (903), the sludge outlet (802) and the second solid phase inlet (901) are communicated through a solid phase sludge conveying pipeline, and the filter pressing liquid outlet (902) and the water quality adjusting inlet (511) are communicated through a filter pressing liquid conveying pipeline.
8. A method for treating hydrofluoric acid-containing wastewater, comprising:
carrying out solid-liquid separation treatment on hydrofluoric acid-containing wastewater to obtain a liquid-phase product and a first solid-phase product;
performing membrane distillation treatment on the liquid-phase product to obtain an enrichment solution;
carrying out ultrafiltration treatment on the enriched liquid to obtain fluorine-containing ion concentrated liquid and filtered water; and
and carrying out reverse osmosis treatment on the fluorine-containing ion concentrated solution and the filtered water to obtain hydrofluoric acid.
9. The method for treating hydrofluoric acid-containing wastewater according to claim 8, wherein the membrane distillation process comprises:
heating the liquid-phase product to obtain a heating liquid;
the heating liquid is subjected to microporous membrane treatment and cooling treatment to obtain the enrichment liquid;
preferably, the temperature of the heating liquid is 30-60 ℃, and the temperature of the enrichment liquid is 5-15 ℃;
more preferably, the microporous membrane is selected from polyvinylidene fluoride and/or polytetrafluoroethylene.
10. The method for treating hydrofluoric acid containing wastewater according to claim 8, wherein the ultrafiltration is performed using an ultrafiltration membrane selected from polyvinylidene fluoride and/or polytetrafluoroethylene.
11. The method for treating hydrofluoric acid-containing wastewater according to any one of claims 8 to 10, further comprising:
mixing the hot residual liquid obtained by the membrane distillation treatment with the reverse osmosis residual liquid obtained by the reverse osmosis treatment, and adjusting the water quality to obtain a material to be subjected to coagulation treatment;
adding a coagulant into the material to be subjected to coagulation treatment, and performing coagulation sedimentation treatment to obtain a supernatant and fluorine-containing solid-phase waste residues;
adjusting the pH of the supernatant to obtain fluorine-containing waste liquid meeting the discharge standard;
preferably, the coagulant comprises a precipitant and a flocculant;
preferably, the weight ratio of the material to be coagulated, the precipitator and the flocculating agent is 100 (210-250) to (1-30);
preferably, the pH value of the coagulating sedimentation treatment is 10-12.
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