Wastewater zero-discharge treatment method and system

Abstract

The present invention provides a method and system for zero-emission treatment of wastewater. The wastewater includes coking wastewater, cold rolling wastewater, power plant desulfurization wastewater, and sintering acid-making wastewater. The treatment method includes: performing first concentration pretreatment on the coking wastewater; performing second concentration pretreatment on the cold rolling wastewater; performing concentrated wastewater pretreatment on the power plant desulfurization wastewater, sintering acid-making wastewater, first concentrated water, and second concentrated water; performing membrane separation and concentration treatment on the first produced water; performing first crystallization treatment on the second produced water; and performing second crystallization treatment on the third concentrated water. The zero-emission treatment method for wastewater provided by the present invention, through the first concentration pretreatment of the coking wastewater and the second concentration pretreatment of the cold rolling wastewater, and then mixing the first concentrated water, second concentrated water, power plant desulfurization wastewater, and sintering acid-making wastewater for concentrated wastewater pretreatment, membrane separation and concentration treatment, first crystallization treatment, and second crystallization treatment, realizes the co-production of salt and nitrate by extracting salt from the wastewater, and reuses the obtained industrial fresh water to achieve zero-emission of wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and particularly relates to a method and system for zero-emission treatment of wastewater. Background Art

[0002] Coking wastewater is a typical refractory industrial wastewater with diverse pollutants, difficult degradation, and high toxicity; cold-rolled wastewater has a high content of organic matter and salt; power plant desulfurization wastewater has characteristics such as high salt, heavy metals, complex composition, corrosiveness, and scaling; sintering acid-making wastewater contains a large amount of impurities such as fluorine, chlorine, mercury, arsenic, and lead, with complex composition and high contents of heavy metals and fluorides. These four types of wastewater are several highly refractory wastewaters generated during the production process of steel plants and are often used for slag flushing or slag smothering digestion. However, due to the high content of organic matter and salt after concentration, problems such as strong equipment odor and equipment corrosion will occur.

[0003] In the wastewater of steel plants, common cations are sodium ions, calcium ions, magnesium ions, and other small amounts of heavy metal salts, and anions are chloride ions, sulfate ions, nitrate ions, etc. At present, the method to achieve zero-emission of wastewater is to first remove heavy metal salts, organic matter, etc., then perform salt separation and crystallization on the remaining cations and anions, and finally recycle the cations and anions in the water resourcefully.

[0004] However, the removal of organic matter in the concentrated water of cold-rolled wastewater, the removal of organic matter and pollutants such as fluorine in coking wastewater, the removal of fluorides in sintering acid-making wastewater, and the removal of heavy metal substances in desulfurization wastewater are all key points in the process of treating highly refractory wastewater. Therefore, how to remove these pollutants through an economical and effective method to achieve zero-emission of wastewater has increasingly become one of the technical problems that need to be solved urgently by those skilled in the art. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and system for zero-emission treatment of wastewater to solve one or more of the problems in the prior art, such as the difficulty in removing pollutants in highly refractory wastewater through an economical and effective method to achieve zero-emission of wastewater.

[0006] To achieve the above object, the present invention is realized through the following technical solutions: A zero-emission treatment method for wastewater, wherein the wastewater includes coking wastewater, cold rolling wastewater, power plant desulfurization wastewater, and sintering sulfuric acid production wastewater. The treatment method includes: performing a first concentration pretreatment on the coking wastewater to obtain first industrial fresh water and first concentrated water; performing a second concentration pretreatment on the cold rolling wastewater to obtain second industrial fresh water and second concentrated water; according to the water qualities of the power plant desulfurization wastewater, the sintering sulfuric acid production wastewater, the first concentrated water, and the second concentrated water, mixing and blending them and then performing a concentrated water pretreatment to obtain first produced water; performing a membrane separation and concentration treatment on the first produced water to obtain third industrial fresh water, second produced water, and third concentrated water; performing a first crystallization treatment on the second produced water; and performing a second crystallization treatment on the third concentrated water.

[0007] Optionally, the performing a first concentration pretreatment on the coking wastewater to obtain first industrial fresh water and first concentrated water includes: conveying the coking wastewater to a first regulating tank; sequentially performing a first sand filtration treatment, a first ultrafiltration treatment, a first resin softening treatment, and a first reverse osmosis treatment on the coking wastewater in the first regulating tank; after the first reverse osmosis treatment, obtaining the first industrial fresh water and the first concentrated water, and using the first industrial fresh water as industrial water for reuse.

[0008] Optionally, the performing a first concentration pretreatment on the coking wastewater to obtain first industrial fresh water and first concentrated water further includes: conveying the backwash water after the first sand filtration treatment and the first ultrafiltration treatment to the first regulating tank after precipitation, conveying the resin acid regeneration waste liquid after the first resin softening treatment to an acidic waste liquid pit, and conveying the resin base regeneration waste liquid after the first resin softening treatment to an alkaline waste liquid pit.

[0009] Optionally, the performing a second concentration pretreatment on the cold rolling wastewater to obtain second industrial fresh water and second concentrated water includes: conveying the cold rolling wastewater to a second regulating tank; sequentially performing a second sand filtration treatment, a second ultrafiltration treatment, a second resin softening treatment, and a second reverse osmosis treatment on the cold rolling wastewater in the second regulating tank; after the second reverse osmosis treatment, obtaining the second industrial fresh water and the second concentrated water, and using the second industrial fresh water as industrial water for reuse.

[0010] Optionally, the performing a second concentration pretreatment on the cold rolling wastewater to obtain second industrial fresh water and second concentrated water further includes: conveying the backwash water after the second sand filtration treatment and the second ultrafiltration treatment to the second regulating tank after precipitation, conveying the resin acid regeneration waste liquid after the second resin softening treatment to the acidic waste liquid pit, and conveying the resin base regeneration waste liquid after the second resin softening treatment to the alkaline waste liquid pit.

[0011] Optionally, based on the water qualities of the desulfurized wastewater from the power plant, the acid-making wastewater from sintering, the first concentrated water, and the second concentrated water, after mixing and blending, the concentrated water is pre-treated to obtain the first produced water, including: conveying the desulfurized wastewater from the power plant and the resin acid regeneration wastewater in the acid waste liquid pit to the third regulation tank, conveying the acid-making wastewater from sintering to the fourth regulation tank, and conveying the first concentrated water and the second concentrated water to the fifth regulation tank; conveying the wastewater in the third regulation tank, the wastewater in the fourth regulation tank, and the wastewater in the fifth regulation tank to the high-density fluoride removal tank for mixing and fluoride removal treatment; conveying the effluent from the high-density fluoride removal tank, the waste liquid in the high-concentration waste liquid pit, and the resin base regeneration wastewater in the alkaline waste liquid pit to the high-density hardness removal tank for hardness removal treatment; conveying the effluent from the high-density hardness removal tank to the high-density COD removal tank for organic matter removal treatment; performing the third sand filtration treatment, the third ultrafiltration treatment, and the third resin softening treatment on the effluent from the high-density COD removal tank; and obtaining the first produced water after the third resin softening treatment.

[0012] Optionally, based on the water qualities of the desulfurized wastewater from the power plant, the acid-making wastewater from sintering, the first concentrated water, and the second concentrated water, after mixing and blending, the concentrated water is pre-treated to obtain the first produced water, further including: conveying the high-concentration backwash water after the third sand filtration treatment and the third ultrafiltration treatment to the high-concentration waste liquid pit, conveying the resin acid regeneration wastewater after the third resin softening treatment to the acid waste liquid pit, and conveying the resin base regeneration wastewater after the third resin softening treatment to the alkaline waste liquid pit.

[0013] Optionally, performing membrane separation and concentration treatment on the first produced water to obtain the third industrial fresh water, the second produced water, and the third concentrated water, including: conveying the first produced water to the low-pressure nanofiltration inlet tank for low-pressure nanofiltration treatment to obtain the third produced water and the fourth concentrated water; performing high-pressure nanofiltration treatment on the fourth concentrated water to obtain the fourth produced water and the third concentrated water; performing purification nanofiltration treatment on the third produced water and the fourth produced water to obtain the fifth produced water and the fifth concentrated water, and conveying the fifth concentrated water to the low-pressure nanofiltration inlet tank; performing high-pressure reverse osmosis treatment on the fifth produced water to obtain the sixth concentrated water and the third industrial fresh water, and using the third industrial fresh water for industrial water reuse; conveying the sixth concentrated water to the carbon remover to obtain the sixth produced water; and performing tubular microfiltration treatment on the sixth produced water to obtain the second produced water.

[0014] Optionally, the first crystallization treatment includes transporting the second produced water to a sodium chloride evaporation crystallization device for evaporation crystallization treatment to obtain sodium chloride crystals and a first mother liquor, transporting the first mother liquor to a miscellaneous salt drying device for drying treatment, and transporting the condensate in the miscellaneous salt drying device to the high-concentration waste liquid pit; the second crystallization treatment includes transporting the third concentrated water to a defluorination sedimentation tank, performing a fourth sand filtration treatment on the produced water of the defluorination sedimentation tank, performing an electrocatalytic oxidation treatment on the produced water after the fourth sand filtration treatment, and transporting the produced water after the electrocatalytic oxidation treatment to a sodium sulfate evaporation crystallization device for evaporation crystallization treatment to obtain anhydrous sodium sulfate and a second mother liquor; and performing a freezing treatment on the second mother liquor to obtain mirabilite crystals and supernatant, dissolving the mirabilite crystals and transporting them to the sodium sulfate evaporation crystallization device, and transporting the supernatant to the high-concentration waste liquid pit.

[0015] To achieve the above object, the present invention also provides a zero-emission wastewater treatment system. The wastewater includes coking wastewater, cold rolling wastewater, power plant desulfurization wastewater, and sintering acid-making wastewater. The treatment system includes: a first concentration pretreatment device configured to perform a first concentration pretreatment on the coking wastewater to obtain a first industrial fresh water and a first concentrated water; a second concentration pretreatment device configured to perform a second concentration pretreatment on the cold rolling wastewater to obtain a second industrial fresh water and a second concentrated water; a concentrated water pretreatment device configured to perform a mixed blending according to the water qualities of the power plant desulfurization wastewater, the sintering acid-making wastewater, the first concentrated water, and the second concentrated water and then perform a concentrated water pretreatment to obtain a first produced water; a membrane separation and concentration treatment device configured to perform a membrane separation and concentration treatment on the first produced water to obtain a third industrial fresh water, a second produced water, and a third concentrated water; a first crystallization treatment device configured to perform a first crystallization treatment on the second produced water; and a second crystallization treatment device configured to perform a second crystallization treatment on the third concentrated water.

[0016] Compared with the prior art, the zero-emission wastewater treatment method and system provided by the present invention have the following beneficial effects:

[0017] The zero-emission wastewater treatment method provided by the present invention, wherein the wastewater includes coking wastewater, cold rolling wastewater, power plant desulfurization wastewater, and sintering acid-making wastewater. The treatment method includes: performing first concentration pretreatment on the coking wastewater to obtain first industrial fresh water and first concentrated water; performing second concentration pretreatment on the cold rolling wastewater to obtain second industrial fresh water and second concentrated water; performing mixed blending on the power plant desulfurization wastewater, the sintering acid-making wastewater, the first concentrated water, and the second concentrated water according to their water qualities, and then performing concentrated water pretreatment to obtain first produced water; performing membrane separation and concentration treatment on the first produced water to obtain third industrial fresh water, second produced water, and third concentrated water; performing first crystallization treatment on the second produced water; and performing second crystallization treatment on the third concentrated water. Thus, the zero-emission wastewater treatment method provided by the present invention can remove most of the suspended solids and microorganisms in the coking wastewater and the cold rolling wastewater, and reduce the turbidity, colloid, bacteria, and most viruses and macromolecular organic matters and other impurities in the coking wastewater and the cold rolling wastewater by performing first concentration pretreatment (exemplarily, including but not limited to first sand filtration treatment) on the coking wastewater and second concentration pretreatment (exemplarily, including but not limited to second sand filtration treatment) on the cold rolling wastewater respectively, so as to avoid clogging of production equipment; by performing mixed blending on the power plant desulfurization wastewater, the sintering acid-making wastewater, the first concentrated water, and the second concentrated water according to their water qualities, and then performing concentrated water pretreatment (exemplarily, including but not limited to defluorination treatment and hardness removal treatment), the characteristics of anions and cations in the wastewater can be utilized to remove fluorine, calcium, magnesium, heavy metals, and organic matters in the wastewater, thereby saving chemicals, reducing operation costs, and reducing the impact on subsequent membrane separation and concentration section and crystallization section; by performing membrane separation and concentration treatment (exemplarily, including but not limited to low-pressure nanofiltration treatment and high-pressure nanofiltration treatment) on the first produced water obtained after concentrated water pretreatment, sodium chloride salt and sodium sulfate salt in the wastewater can be separated and further separated and concentrated, laying a foundation for the subsequent crystallization section; by performing first crystallization treatment on the second produced water obtained after membrane separation and concentration treatment, sodium chloride crystals meeting industrial standards can be produced; by performing second crystallization treatment (exemplarily, including but not limited to electrocatalytic oxidation treatment) on the third concentrated water obtained after membrane separation and concentration treatment, the enrichment of organic matters can be reduced, and the produced water quality and salt output quality can be ensured. By performing first concentration pretreatment on the coking wastewater to obtain first concentrated water and second concentration pretreatment on the cold rolling wastewater to obtain second concentrated water, then performing mixed blending on the first concentrated water, the second concentrated water, the power plant desulfurization wastewater, and the sintering acid-making wastewater according to their water qualities, and then performing concentrated water pretreatment, membrane separation and concentration treatment, first crystallization treatment, and second crystallization treatment, salt and nitrate co-production can be realized by wastewater salt extraction, and industrial fresh water can be obtained as recycled water, thereby achieving zero-emission of wastewater.

[0018] Further, for the concentrated water pretreatment after mixing and blending according to the water qualities of the desulfurized wastewater of the power plant, the sintering acid-making wastewater, the first concentrated water, and the second concentrated water to obtain the first produced water, the method includes: conveying the desulfurized wastewater of the power plant and the resin acid regeneration wastewater in the acidic waste liquid pit to the third regulating tank, conveying the sintering acid-making wastewater to the fourth regulating tank, and conveying the first concentrated water and the second concentrated water to the fifth regulating tank; conveying the wastewater in the third regulating tank, the wastewater in the fourth regulating tank, and the wastewater in the fifth regulating tank to the high-density fluoride removal tank for mixing and fluoride removal treatment; conveying the effluent of the high-density fluoride removal tank, the waste liquid in the high-concentration waste liquid pit, and the resin alkali regeneration wastewater in the alkaline waste liquid pit to the high-density hardness removal tank for hardness removal treatment; conveying the effluent of the high-density hardness removal tank to the high-density COD removal tank for organic matter removal treatment; performing the third sand filtration treatment, the third ultrafiltration treatment, and the third resin softening treatment on the effluent of the high-density COD removal tank; and obtaining the first produced water after the third resin softening treatment. Thus, for the zero-discharge wastewater treatment method provided by the present invention, by setting the third regulating tank, the fourth regulating tank, and the fifth regulating tank, the water quality and water volume of the wastewater can be adjusted to ensure continuous production of the equipment; by conveying the wastewater in the third regulating tank, the wastewater in the fourth regulating tank, and the wastewater in the fifth regulating tank to the high-density fluoride removal tank for mixing and fluoride removal treatment, the high calcium ion characteristic in the wastewater can be utilized to reduce the fluoride ion concentration, thereby saving chemicals; by conveying the effluent of the high-density fluoride removal tank, the waste liquid in the high-concentration waste liquid pit, and the resin alkali regeneration wastewater in the alkaline waste liquid pit to the high-density hardness removal tank for hardness removal treatment, the hardness in the water body can be removed, and the waste liquid can be utilized to adjust the pH, thereby saving the chemicals for pH adjustment; by setting the high-density COD removal tank, the organic matter in the wastewater can be removed. Through multi-stage high-density treatment, fluorine, calcium, magnesium, heavy metals, and organic matter in the wastewater can be removed, thereby ensuring the stable operation of the subsequent membrane separation and concentration treatment section and avoiding risks such as subsequent scaling and fouling. By performing the third sand filtration treatment on the effluent of the high-density COD removal tank, the suspended solids in the wastewater can be removed; by the third ultrafiltration treatment, the microorganisms in the wastewater can be removed and the suspended particles in the wastewater can be further removed; by the third resin softening treatment, part of the calcium and magnesium ions in the wastewater can be removed, reducing the hardness in the wastewater.

[0019] Furthermore, after mixing and blending according to the water qualities of the desulfurized wastewater of the power plant, the sintering acid-making wastewater, the first concentrated water, and the second concentrated water, and then performing pretreatment on the concentrated water to obtain the first produced water, it further includes: conveying the highly concentrated backwash water after the third sand filtration treatment and the third ultrafiltration treatment to the highly concentrated waste liquid pit, conveying the resin acid regeneration waste liquid after the third resin softening treatment to the acidic waste liquid pit, and conveying the resin alkali regeneration waste liquid after the third resin softening treatment to the alkaline waste liquid pit. Thus, the zero-emission wastewater treatment method provided by the present invention can save chemicals by collecting the waste liquids generated during the wastewater treatment process, conveying the waste liquids in the highly concentrated waste liquid pit and the alkaline waste liquid pit to the high-density hardening removal tank, and conveying the resin acid regeneration waste liquid in the acidic waste liquid pit to the third adjustment tank, thereby laying a foundation for economically and effectively removing pollutants in the wastewater.

[0020] Since the zero-emission wastewater treatment system provided by the present invention belongs to the same inventive concept as the zero-emission wastewater treatment method described in any one of the above, therefore, the zero-emission wastewater treatment system provided by the present invention has at least all the advantages of the zero-emission wastewater treatment method. Here, it will not be elaborated again. For more detailed content, please refer to the relevant description of the beneficial effects of the zero-emission wastewater treatment method above. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall steps of a zero-emission wastewater treatment method provided in Embodiment 1 of the present invention;

[0022] Figure 2 It is a schematic diagram of the specific process of a zero-emission wastewater treatment method provided in Embodiment 1 of the present invention;

[0023] Figure 3 It is a structural block diagram of a zero-emission wastewater treatment system provided in Embodiment 2 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0024] The following further elaborates on the zero - discharge treatment method and system for wastewater proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description, the advantages and features of the present invention will be clearer. It should be noted that the accompanying drawings are all in a very simplified form and use non - precise scales, only for conveniently and clearly assisting in explaining the purpose of the embodiments of the present invention. In order to make the purpose, features, and advantages of the present invention more obvious and understandable, please refer to the accompanying drawings. It should be known that the structures, scales, sizes, etc. shown in the drawings of this specification are only used to cooperate with the content disclosed in the specification for those skilled in this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Any modification of the structure, change in the proportional relationship, or adjustment of the size, in the case of being the same or similar to the effects that the present invention can produce and the purposes that can be achieved, should still fall within the scope covered by the technical content disclosed by the present invention. The specific design features of the present invention disclosed herein, such as specific dimensions, directions, positions, and shapes, will be partially determined by the specific application and usage environment. Also, in the following described embodiments, sometimes the same reference numerals are used commonly between different drawings to represent the same part or parts with the same function, and the repeated description thereof is omitted.

[0025] Embodiment 1

[0026] This embodiment provides a zero - discharge treatment method for wastewater, where the wastewater includes coking wastewater, cold - rolling wastewater, power - plant desulfurization wastewater, and sintering acid - making wastewater. Specifically, please refer to Figure 1 and Figure 2 , Figure 1 which is a schematic diagram of the overall steps of a zero - discharge treatment method for wastewater provided in this embodiment; Figure 2 which is a schematic diagram of the specific process of a zero - discharge treatment method for wastewater provided in this embodiment. It can be seen from Figure 1 and Figure 2 that the treatment method includes:

[0027] S100: Conduct a first concentration pretreatment on the coking wastewater to obtain first industrial fresh water and first concentrated water;

[0028] S200: Conduct a second concentration pretreatment on the cold - rolling wastewater to obtain second industrial fresh water and second concentrated water;

[0029] S300: According to the water quality of the power - plant desulfurization wastewater, the sintering acid - making wastewater, the first concentrated water, and the second concentrated water, conduct mixing and blending and then conduct concentrated - water pretreatment to obtain first produced water;

[0030] S400: Conduct membrane separation and concentration treatment on the first produced water to obtain third industrial fresh water, second produced water, and third concentrated water;

[0031] S500: Perform a first crystallization treatment on the second produced water;

[0032] S600: Perform a second crystallization treatment on the third concentrated water.

[0033] Thus, for the zero - discharge wastewater treatment method provided in this embodiment, by separately performing a first concentration pretreatment (exemplarily, including but not limited to a first sand filtration treatment) on the coking wastewater and a second concentration pretreatment (exemplarily, including but not limited to a second sand filtration treatment) on the cold - rolling wastewater, most of the suspended solids, microorganisms in the coking wastewater and cold - rolling wastewater can be removed, and the turbidity, colloid, bacteria, and most of the viruses and macromolecular organic matters and other impurities in the coking wastewater and cold - rolling wastewater can be reduced, avoiding clogging of production equipment; by mixing and blending according to the water qualities of the power - plant desulfurization wastewater, the sintering acid - making wastewater, the first concentrated water, and the second concentrated water, and then performing a concentrated - water pretreatment (exemplarily, including but not limited to defluorination treatment and hardness removal treatment), the characteristics of anions and cations in the wastewater can be utilized to remove fluorine, calcium, magnesium, heavy metals, and organic matters in the wastewater, thereby saving chemicals, reducing operating costs, and reducing the impact on the subsequent membrane separation and concentration section and crystallization section; by performing a membrane separation and concentration treatment (exemplarily, including but not limited to low - pressure nanofiltration treatment and high - pressure nanofiltration treatment) on the first produced water obtained after the concentrated - water pretreatment, sodium chloride salts and sodium sulfate salts in the wastewater can be separated, further separated, and concentrated, laying a foundation for the subsequent crystallization section; by performing a first crystallization treatment on the second produced water obtained after the membrane separation and concentration treatment, sodium chloride crystals meeting industrial standards can be produced; by performing a second crystallization treatment (exemplarily, including but not limited to electro - catalytic oxidation treatment) on the third concentrated water obtained after the membrane separation and concentration treatment, the enrichment of organic matters can be reduced, ensuring the water quality of the produced water and the quality of the produced salts. By performing a first concentration pretreatment on the coking wastewater to obtain the first concentrated water and a second concentration pretreatment on the cold - rolling wastewater to obtain the second concentrated water, then mixing and blending according to the water qualities of the first concentrated water, the second concentrated water, the power - plant desulfurization wastewater, and the sintering acid - making wastewater, and then performing a concentrated - water pretreatment, a membrane separation and concentration treatment, a first crystallization treatment, and a second crystallization treatment, through wastewater salt extraction, co - production of salt and nitrate is realized, and industrial fresh water is obtained as recycled water, thereby achieving zero - discharge of wastewater.

[0034] It should be particularly noted that, as can be understood by those skilled in the art, the present invention does not overly limit the sequence of the above - mentioned steps S100 and S200. In some embodiments, step S100 can be performed first, and then step S200; in other embodiments, step S200 can be performed first, and then step S100; in other embodiments, steps S100 and S200 can also be performed simultaneously.

[0035] Preferably, the first concentration pretreatment of the coking wastewater to obtain the first industrial fresh water and the first concentrated water includes: conveying the coking wastewater to a first regulation tank; sequentially performing a first sand filtration treatment, a first ultrafiltration treatment, a first resin softening treatment, and a first reverse osmosis treatment on the coking wastewater in the first regulation tank; obtaining the first industrial fresh water and the first concentrated water after the first reverse osmosis treatment, and using the first industrial fresh water as industrial water for reuse. Thus, by conveying the coking wastewater to the first regulation tank, the water quality and water volume of the coking wastewater can be regulated to ensure continuous production of the equipment; through the first sand filtration treatment, suspended solids in the coking wastewater can be removed; through the first ultrafiltration treatment, microorganisms in the coking wastewater and further suspended particles in the coking wastewater can be removed; through the first resin softening treatment, part of the calcium and magnesium ions in the coking wastewater can be removed to reduce the hardness of the coking wastewater; through the first reverse osmosis treatment, inorganic salts and organic matters can be intercepted, making the produced water meet the industrial water quality requirements.

[0036] Further, the first concentration pretreatment of the coking wastewater to obtain the first industrial fresh water and the first concentrated water further includes: conveying the backwash water after the first sand filtration treatment and the first ultrafiltration treatment to the first regulation tank after precipitation, conveying the resin acid regeneration waste liquid after the first resin softening treatment to an acidic waste liquid pit, and conveying the resin alkali regeneration waste liquid after the first resin softening treatment to an alkaline waste liquid pit. Thus, by collecting the waste liquids generated during the coking wastewater treatment process, the chemicals for the reaction in the subsequent concentrated water pretreatment section can be saved, laying a foundation for economically and effectively removing pollutants in the wastewater.

[0037] Specifically, first convey the coking wastewater to the first regulation tank to make the discharge of the coking wastewater uniform through the first regulation tank; then, convey the coking wastewater to a sand filter through a lift pump for the first sand filtration treatment, which can remove the suspended solids in the water body to below 5 ppm. The produced water after the first sand filtration treatment enters an ultrafiltration inlet tank, and its backwash water is conveyed to the first regulation tank after precipitation; then, convey the coking wastewater in the ultrafiltration inlet tank to an ultrafiltration device through a lift pump for the first ultrafiltration treatment, which can reduce the SDI (Sludge Density Index) in the coking wastewater to below 3, the turbidity to below 0.2, and the removal rates of microorganisms, bacteria, Escherichia coli, and pathogens to be greater than 99.99%. The produced water after the first ultrafiltration treatment enters a resin inlet tank, and its backwash water is conveyed to the first regulation tank after precipitation; then, convey the coking wastewater in the resin inlet tank to a resin softening and hardness removal device through a lift pump for the first resin softening treatment, which can control the Ca 2+ ≤3.0 ppm, Mg 2+≤0.5 ppm. After the first resin softening treatment, the produced water enters the first reverse osmosis feed water tank, the resin acid regeneration waste liquid enters the acidic waste liquid pit, and the resin caustic regeneration waste liquid enters the alkaline waste liquid pit. Finally, the coking wastewater in the first reverse osmosis feed water tank is transported to the security filter by a lift pump and then to the reverse osmosis membrane device by a high-pressure pump for the first reverse osmosis treatment. The first industrial fresh water obtained after the first reverse osmosis treatment meets the industrial water quality requirements and is recycled within the factory. The concentrated water obtained after the first reverse osmosis treatment is the first concentrated water.

[0038] For example, in one specific example, the incoming water volume of the coking wastewater after being transported to the first regulation tank is 125 m 3 / h. After the first sand filtration treatment, the first ultrafiltration treatment, the first resin softening treatment, and the first reverse osmosis treatment, the water volume of the first concentrated water obtained is 38 m 3 / h. The water quality indicators of the first concentrated water are: TDS = 30700 ppm, TOC = 96 ppm, Ca 2 + = 9.8 ppm, F - = 61 ppm, Cl - = 7300 ppm, SO4 2- = 10800 ppm, SiO2 = 15 ppm, NO3 - = 132 ppm.

[0039] Preferably, in step S200, the second concentration pretreatment of the cold rolling wastewater to obtain the second industrial fresh water and the second concentrated water includes: transporting the cold rolling wastewater to the second regulation tank; sequentially performing the second sand filtration treatment, the second ultrafiltration treatment, the second resin softening treatment, and the second reverse osmosis treatment on the cold rolling wastewater in the second regulation tank; obtaining the second industrial fresh water and the second concentrated water after the second reverse osmosis treatment, and recycling the second industrial fresh water as industrial water. Thus, by transporting the cold rolling wastewater to the second regulation tank, the water quality and water volume of the cold rolling wastewater can be adjusted to ensure continuous production of the equipment; through the second sand filtration treatment, the suspended solids in the cold rolling wastewater can be removed; through the second ultrafiltration treatment, the microorganisms in the cold rolling wastewater and further the suspended particles in the cold rolling wastewater can be removed; through the second resin softening treatment, part of the calcium and magnesium ions in the cold rolling wastewater can be removed, reducing the hardness of the coking wastewater; through the second reverse osmosis treatment, the second reverse osmosis treatment includes the first-stage reverse osmosis treatment and the second-stage reverse osmosis treatment, which can intercept inorganic salts and organic substances, enabling the second industrial fresh water to meet the industrial water quality requirements and be recycled within the factory.

[0040] Further, the second concentration pretreatment of the cold rolling wastewater to obtain second industrial fresh water and second concentrated water further includes: conveying the backwash water after the second sand filtration treatment and the second ultrafiltration treatment to the second adjustment tank after precipitation, conveying the resin acid regeneration waste liquid after the second resin softening treatment to the acidic waste liquid pit, and conveying the resin alkali regeneration waste liquid after the second resin softening treatment to the alkaline waste liquid pit. Thus, by collecting the waste liquid generated during the treatment of cold rolling wastewater, it is possible to save chemicals for the reaction in the subsequent concentrated water pretreatment section, thereby laying a foundation for economically and effectively removing pollutants in the wastewater.

[0041] Specifically, first, the cold rolling wastewater is conveyed to the second adjustment tank to make the discharge of the cold rolling wastewater uniform through the second adjustment tank; then, the cold rolling wastewater is conveyed to a sand filter for the second sand filtration treatment by a lift pump, and the suspended solids in the water body can be removed to less than 5 ppm. The water produced after the second sand filtration treatment enters the ultrafiltration inlet tank, and its backwash water is conveyed to the second adjustment tank after precipitation; then, the cold rolling wastewater in the ultrafiltration inlet tank is conveyed to an ultrafiltration device for the second ultrafiltration treatment by a lift pump, and the SDI (Sludge Density Index) in the cold rolling wastewater can be reduced to less than 3, the turbidity can be reduced to less than 0.2, and the removal rates of microorganisms, bacteria, Escherichia coli, and pathogens are greater than 99.99%. The water produced after the second ultrafiltration treatment enters the resin inlet tank, and its backwash water is conveyed to the second adjustment tank after precipitation; then, the cold rolling wastewater in the resin inlet tank is conveyed to a resin softening and hardness removal device for the second resin softening treatment by a lift pump, and the Ca 2+ ≤3.0 ppm, Mg 2+ ≤0.5 ppm can be controlled. The water produced after the second resin softening treatment enters the second reverse osmosis inlet tank, its resin acid regeneration waste liquid enters the acidic waste liquid pit, and its resin alkali regeneration waste liquid enters the alkaline waste liquid pit; then, the cold rolling wastewater in the second reverse osmosis inlet tank is conveyed to a security filter by a lift pump and then conveyed to a reverse osmosis membrane device by a high-pressure pump for the second reverse osmosis treatment. The second industrial fresh water obtained after the second reverse osmosis treatment meets the industrial water quality requirements and is reused in the factory, and the concentrated water obtained after the second reverse osmosis treatment is the second concentrated water.

[0042] Exemplarily, in one specific example, the incoming water volume of the cold rolling wastewater conveyed to the second adjustment tank is 200 m 3 / h. After the second sand filtration treatment, the second ultrafiltration treatment, the second resin softening treatment, and the second reverse osmosis treatment, the water volume of the obtained second concentrated water is 18 m 3 / h, and the water quality of the second concentrated water is: TDS = 9600 ppm, TOC = 40 ppm, Ca 2+ = 550 ppm, F - = 2 ppm, Cl -= 5100 ppm, SO4 2- = 550 ppm, SiO2 = 15 ppm, NO3 - = 30 ppm.

[0043] Preferably, in step S300, according to the water qualities of the desulfurized wastewater of the power plant, the sintering acid-making wastewater, the first concentrated water, and the second concentrated water, after mixing and blending, the concentrated water is pretreated to obtain the first produced water, including:

[0044] S310: Transport the desulfurized wastewater of the power plant and the resin acid regeneration wastewater in the acidic waste liquid pit to the third regulation tank, transport the sintering acid-making wastewater to the fourth regulation tank, and transport the first concentrated water and the second concentrated water to the fifth regulation tank;

[0045] S320: Transport the wastewater in the third regulation tank, the wastewater in the fourth regulation tank, and the wastewater in the fifth regulation tank to the high-density fluoride removal tank for mixing and fluoride removal treatment;

[0046] S330: Transport the effluent of the high-density fluoride removal tank, the waste liquid in the high-concentration waste liquid pit, and the resin base regeneration wastewater in the alkaline waste liquid pit to the high-density hardness removal tank for hardness removal treatment;

[0047] S340: Transport the effluent of the high-density hardness removal tank to the high-density COD removal tank for organic matter removal treatment;

[0048] S350: Conduct the third sand filtration treatment, the third ultrafiltration treatment, and the third resin softening treatment on the effluent of the high-density COD removal tank;

[0049] S360: Obtain the first produced water after the third resin softening treatment.

[0050] Thus, by setting up the third regulating tank, the fourth regulating tank and the fifth regulating tank, the water quality and water volume of the wastewater can be regulated to ensure the continuous production of the equipment. By transporting the wastewater in the third regulating tank, the fourth regulating tank and the fifth regulating tank to the high-density defluorination tank for mixing and defluorination treatment, the high calcium ion characteristics in the wastewater can be utilized to reduce the fluoride ion concentration, thereby saving chemicals. By transporting the effluent from the high-density defluorination tank, the waste liquid in the high-concentration waste liquid pit and the resin alkali regeneration waste liquid in the alkaline waste liquid pit to the high-density hardness removal tank for hardness removal treatment, the hardness in the water body can be removed, and the waste liquid can be utilized to adjust the pH, thus saving the chemicals for pH adjustment. By setting up the high-density COD removal tank, the organic matter in the wastewater can be removed. Through multi-stage high-density treatment, fluorine, calcium, magnesium, heavy metals, organic matter, etc. in the wastewater can be removed, thereby ensuring the stable operation of the subsequent membrane separation and concentration treatment section and avoiding risks such as subsequent scaling and fouling. By performing the third sand filtration treatment on the effluent from the high-density COD removal tank, the suspended solids in the wastewater can be removed. By performing the third ultrafiltration treatment, the microorganisms in the wastewater can be removed and the suspended particles in the wastewater can be further removed. By performing the third resin softening treatment, part of the calcium and magnesium ions in the wastewater can be removed, reducing the hardness of the wastewater.

[0051] Furthermore, based on the water quality of the desulfurization wastewater from the power plant, the sintering acid-making wastewater, the first concentrated water and the second concentrated water, after mixing and blending, pre-treatment of the concentrated water is carried out to obtain the first produced water. It also includes: transporting the high-concentration backwash water after the third sand filtration treatment to the high-concentration waste liquid pit, transporting the resin acid regeneration waste liquid after the third resin softening treatment to the acidic waste liquid pit, and transporting the resin alkali regeneration waste liquid after the third resin softening treatment to the alkaline waste liquid pit. Thus, by collecting the waste liquid generated during the wastewater treatment process, transporting the waste liquid in the high-concentration waste liquid pit and the alkaline waste liquid pit to the high-density hardness removal tank, and transporting the resin acid regeneration waste liquid in the acidic waste liquid pit to the third regulating tank, chemicals can be saved, laying a foundation for the economical and effective removal of pollutants in the wastewater.

[0052] Specifically, first, the wastewater in the third regulating pond, the fourth regulating pond, and the fifth regulating pond is transported to the high-density defluorination pond for mixing. On the one hand, according to the characteristics of anions and cations in the wastewater, the high-concentration calcium ions in the resin acid regeneration waste liquid of the acidic waste liquid pit and the heavy metal ions in the power plant desulfurization wastewater can combine with the high-concentration fluoride ions in the sintering acid-making wastewater to form precipitates, thereby removing fluorine, calcium, magnesium, heavy metals, and organic matters in the wastewater. On the other hand, the resin acid regeneration waste liquid can play a role in acid-base neutralization and reagent saving with the sintering acid-making wastewater. Through the high-density defluorination pond, the fluoride ions are removed to below 20 ppm by using defluorination agents, and the water-containing sludge enters the sludge thickening pond. Then, the effluent of the high-density defluorination pond, the waste liquid of the high-concentration waste liquid pit, and the resin base regeneration waste liquid of the alkaline waste liquid pit are transported to the high-density hardness removal pond, and sodium carbonate is added, which can adjust the pH and remove the hardness in the water body, and control the Ca 2+ ≤ 40 ppm, Mg 2+ ≤ 5 ppm, and the water-containing sludge enters the sludge thickening pond. Next, the effluent of the high-density hardness removal pond is transported to the high-density COD removal pond, and organic matter adsorption agents are added, which can adsorb and remove the organic matters in the wastewater, and control the TOC of the effluent of the high-density COD removal pond ≤ 60 ppm, and the water-containing sludge enters the sludge thickening pond, and the effluent of the high-density COD removal pond enters the filtration inlet pond. Finally, the wastewater in the filtration inlet pond is transported to the sand filter through a lift pump for the third sand filtration treatment, which can remove the suspended solids in the water body to below 5 ppm. The water produced after the third sand filtration treatment enters the ultrafiltration inlet pond, and its high-concentration backwash water enters the high-concentration waste liquid pit; the wastewater in the ultrafiltration inlet pond is transported to the ultrafiltration device through a lift pump for the third ultrafiltration treatment, which can reduce the SDI (sludge density index) in the wastewater to below 3, the turbidity to below 0.2, and the removal rates of microorganisms, bacteria, Escherichia coli, and pathogens are greater than 99.99%. The water produced after the third ultrafiltration treatment enters the resin inlet pond, and its high-concentration backwash water enters the high-concentration waste liquid pit; then the wastewater in the resin inlet pond is transported to the resin softening and hardness removal device through a lift pump for the third resin softening treatment. The first produced water is obtained after the third resin softening treatment, which can control the Ca 2+ ≤ 2.0 ppm, Mg 2+ ≤ 0.5 ppm, the resin acid regeneration waste liquid enters the acidic waste liquid pit, and the resin base regeneration waste liquid enters the alkaline waste liquid pit.

[0053] Exemplarily, in one specific example, the water quality indexes of the sintering acid-making wastewater are: TDS = 112000 ppm, TOC = 20 ppm, Ca 2+ = 30 ppm, F - = 610 ppm, Cl - = 44400 ppm, SO4 2- = 21700 ppm, SiO2 = 115 ppm, NO3- = 100 ppm; The water quality of the desulfurized wastewater from the power plant is: TDS = 37500 ppm, TOC = 40 ppm, Ca 2+ = 1000 ppm, F - = 4 ppm, Cl - = 16000 ppm, SO4 2- = 6800 ppm, SiO2 = 3 ppm, NO3 - = 450 ppm; In the resin acid regeneration waste liquid: Ca 2+ = 3500 ppm. Control the water volume of the desulfurized wastewater from the power plant in the third regulation tank to be 9.5 m 3 / h, the water volume of the resin acid regeneration waste liquid in the third regulation tank to be 6.5 m 3 / h, the water volume of the sintering acid-making wastewater in the fourth regulation tank to be 7.5 m 3 / h, and the water volume of the concentrated water in the fifth regulation tank to be 56 m 3 / h. First, convey the wastewater in the third regulation tank, the fourth regulation tank, and the fifth regulation tank to the high-density fluoride removal tank for mixing, and add fluoride removal agents, coagulants, and flocculants to control the fluoride ions in the effluent of the high-density fluoride removal tank to be less than 20 ppm. Then, convey the effluent of the high-density fluoride removal tank, the waste liquid in the high-concentration waste liquid pit, and the resin alkali regeneration waste liquid in the alkaline waste liquid pit to the high-density hardness removal tank, and add sodium carbonate, which can adjust the pH and remove the hardness in the water body, so that the Ca 2+ ≤ 40 ppm, Mg 2+ ≤ 5 ppm in the effluent of the high-density hardness removal tank. Next, the effluent of the high-density hardness removal tank enters the high-density COD removal tank, and an organic matter adsorption agent is added to complete the removal of organic matter. The sludge generated during the multi-stage high-density treatment process is collected to the sludge thickening tank through a sludge pump. The water quality of the effluent after multi-stage high-density treatment is: TDS = 38000 ppm, TOC = 60 ppm, Ca 2+ = 40 ppm, F - = 18 ppm, Cl - = 13600 ppm, SO4 2- = 9800 ppm, SiO2 = 20 ppm, NO3 - = 130 ppm; The water volume of the effluent after multi-stage high-density treatment is 134 m 3 / h. Finally, the effluent after multi-stage high-density treatment is transported to a shallow sand filter for the third sand filtration treatment, which can remove large suspended solids with a particle size above 2 μm in the water body; then the effluent of the shallow sand filter is transported to an ultrafiltration device for the third ultrafiltration treatment, reducing the SDI (sludge density index) in the wastewater to below 3 and the turbidity to below 0.2, and the removal rates of microorganisms, bacteria, Escherichia coli, and pathogens are greater than 99.99%; the water produced after the third ultrafiltration treatment is softened by chelating resin for the third resin softening treatment to further remove heavy metals in the wastewater, making Ca 2+ ≤1.0 ppm, Mg 2+ ≤0.2 ppm. The water volume of the first produced water after the third sand filtration treatment, the third ultrafiltration treatment, and the third resin softening treatment is 116.5 m 3 / h, and the water quality is: TDS = 38000 ppm, TOC = 60 ppm, Ca 2+ = 1 ppm, F - = 18 ppm, Cl - = 13600 ppm, SO4 2- = 9800 ppm, SiO2 = 20 ppm, NO3 - = 130 ppm.

[0054] Preferably, in step S400, the membrane separation and concentration treatment of the first produced water to obtain the third industrial fresh water, the second produced water and the third concentrated water includes: conveying the first produced water to a low-pressure nanofiltration inlet tank for low-pressure nanofiltration treatment to obtain the third produced water and the fourth concentrated water; performing high-pressure nanofiltration treatment on the fourth concentrated water to obtain the fourth produced water and the third concentrated water; performing purification nanofiltration treatment on the third produced water and the fourth produced water to obtain the fifth produced water and the fifth concentrated water, and conveying the fifth concentrated water to the low-pressure nanofiltration inlet tank; performing high-pressure reverse osmosis treatment on the fifth produced water to obtain the sixth concentrated water and the third industrial fresh water, and using the third industrial fresh water for industrial water reuse; conveying the sixth concentrated water to a decarbonator to obtain the sixth produced water; performing tubular microfiltration treatment on the sixth produced water to obtain the second produced water. Thus, through low-pressure nanofiltration treatment, nanofiltration salt separation can be carried out to preliminarily separate sodium sulfate and sodium chloride; through high-pressure nanofiltration treatment, further nanofiltration concentration and salt separation can be carried out to further concentrate sodium sulfate; through purification nanofiltration treatment, the third produced water obtained after low-pressure nanofiltration treatment and the fourth produced water obtained after high-pressure nanofiltration treatment can be subjected to nanofiltration salt separation to separate sulfate ions from the water body, laying a foundation for sodium chloride salt extraction; through high-pressure reverse osmosis treatment on the fifth produced water obtained after purification nanofiltration treatment, the fifth produced water can be concentrated to obtain the sixth concentrated water, laying a foundation for the subsequent first crystallization treatment section; by setting a decarbonator, the alkalinity in the sixth concentrated water can be removed, thus avoiding scaling; through tubular microfiltration treatment on the sixth produced water, fluoride ions and silicon ions can be removed from the wastewater in the form of sludge, thus avoiding scaling and corrosion of subsequent crystallization equipment.

[0055] Specifically, the first produced water enters the low-pressure nanofiltration feed water tank. The first produced water is lifted by a lift pump, passes through a security filter and a high-pressure pump, and then enters the first-stage nanofiltration membrane in the low-pressure nanofiltration device. It is pressurized between stages and enters the second-stage nanofiltration membrane for nanofiltration salt separation to separate sodium sulfate from sodium chloride, obtaining the third produced water and the fourth concentrated water. The third produced water enters the purified nanofiltration feed water tank, and the fourth concentrated water enters the high-pressure nanofiltration feed water tank. The wastewater in the high-pressure nanofiltration feed water tank is lifted by a lift pump, passes through a security filter and a high-pressure pump, and enters the high-pressure nanofiltration device for further nanofiltration concentration and salt separation to further concentrate sodium sulfate, obtaining the third concentrated water and the fourth produced water. The fourth produced water enters the purified nanofiltration feed water tank, and the water-containing sludge enters the sludge thickening tank. The purified nanofiltration feed water tank collects the third produced water and the fourth produced water. The wastewater in the purified nanofiltration feed water tank is lifted by a lift pump, passes through a security filter and a high-pressure pump, and enters the purified nanofiltration device for nanofiltration salt separation to separate sulfate ions from the water body, obtaining the fifth produced water and the fifth concentrated water. The fifth concentrated water containing sulfate ions flows back to the low-pressure nanofiltration feed water tank and is mixed with the first produced water and then enters the low-pressure nanofiltration device to separate divalent sulfates. The fifth produced water enters the high-pressure reverse osmosis feed water tank. The wastewater in the high-pressure reverse osmosis feed water tank is lifted by a lift pump, passes through a security filter and a high-pressure pump, and enters the high-pressure reverse osmosis device for concentration. The TDS of the produced water obtained after high-pressure reverse osmosis treatment is <800 ppm, and the water quality is good, which is used as the in-plant recycled water. The TDS of the sixth concentrated water obtained after high-pressure reverse osmosis treatment is >50000 ppm. The sixth concentrated water is sent to a decarbonator to remove the alkalinity in the water body, obtaining the sixth produced water. The sixth produced water enters the high-pressure reverse osmosis effluent tank. The wastewater in the high-pressure reverse osmosis effluent tank is lifted by a lift pump to a tubular microfiltration reaction tank. Defluorination and desilication agents are added to the tubular microfiltration reaction tank to generate fluorosilicate sludge flocs. After tubular microfiltration, filtration, and cyclic concentration, the sludge volume increases in the circulation tank and is finally pumped to the sludge thickening tank by a sludge pump. The second produced water is obtained after tubular microfiltration treatment.

[0056] Exemplarily, in one specific example, the water volume of the purified nanofiltration feed water is 115.5 m 3 / h, and the water volume of the fifth produced water obtained after purified nanofiltration treatment is 100 m 3 / h; The fifth produced water is further treated by high-pressure reverse osmosis. The TDS of the purified nanofiltration feed water is concentrated from 25100 ppm to 71000 ppm. The TDS of the sixth concentrated water is 71000 ppm. The TDS of the third industrial fresh water obtained after high-pressure reverse osmosis treatment is 683 ppm, which is used as the in-plant recycled water for reuse; After the sixth concentrated water removes alkalinity through a decarbonator and removes fluorosilicate by adding medicine in tubular microfiltration, it is used as the sodium chloride evaporation crystallization material.

[0057] Preferably, the first crystallization treatment in step S500 includes transporting the second produced water to a sodium chloride crystallization device for evaporation crystallization treatment to obtain sodium chloride crystals and a first mother liquor, transporting the first mother liquor to a miscellaneous salt drying device for drying treatment, and transporting the condensate in the miscellaneous salt drying device to the high-concentration waste liquid pit. Thus, sodium chloride crystals can be obtained through evaporation crystallization treatment; after transporting the first mother liquor to the miscellaneous salt drying device for drying treatment, the salts in the first mother liquor become solids, and the evaporation condensate is transported to the high-concentration waste liquid pit for reuse.

[0058] Specifically, the second produced water enters the sodium chloride crystallization inlet tank and is lifted to the sodium chloride evaporation crystallization device by a lift pump, and sodium chloride meeting industrial standards is obtained through the "thermal MVR" process. In addition, it should be noted that the condensate in the miscellaneous salt drying device enters the high-concentration waste liquid pit, so that it can return to the hardening and high-density pond for re-treatment.

[0059] Further, the second crystallization treatment in step S600 includes transporting the third concentrated water to a defluorination sedimentation tank, performing a fourth sand filtration treatment on the produced water of the defluorination sedimentation tank, performing an electrocatalytic oxidation treatment on the produced water after the fourth sand filtration treatment, and transporting the produced water after the electrocatalytic oxidation treatment to a sodium sulfate crystallization device for evaporation crystallization treatment to obtain anhydrous sodium sulfate and a second mother liquor; and performing a freezing treatment on the second mother liquor to obtain mirabilite crystals and supernatant, dissolving the mirabilite crystals and transporting them to the sodium sulfate crystallization device, and transporting the supernatant to the high-concentration waste liquid pit. Thus, fluoride ions in the third concentrated water can be removed through the defluorination sedimentation tank and the fourth sand filtration treatment, laying a foundation for the evaporation crystallization of sodium sulfate; through electrocatalytic oxidation treatment, organic substances can be removed, and anhydrous sodium sulfate can be obtained through evaporation crystallization treatment.

[0060] Specifically, the third concentrated water enters the defluorination sedimentation tank, and a defluorinating agent is added to remove fluoride ions, controlling F - < 40 ppm; the produced water of the defluorination sedimentation tank is filtered by a sand filter and enters the electrocatalytic oxidation inlet tank. After removing organic substances in the material through the electrocatalytic oxidation device, the produced water enters the sodium sulfate crystallization inlet tank and is lifted to the sodium sulfate evaporation crystallization device by a lift pump. Through the "thermal MVR" process and the "freezing and nitre precipitation reflux" process, a second mother liquor and anhydrous sodium sulfate meeting industrial standards are obtained; the second mother liquor is frozen to obtain mirabilite crystals and supernatant, and the mirabilite crystals are redissolved and transported to the sodium sulfate evaporation crystallization device. In addition, the supernatant is transported to the high-concentration waste liquid pit, so that it can return to the hardening and high-density pond for re-treatment.

[0061] Specifically, in one exemplary embodiment, the water quality of the sodium chloride evaporation crystallization inlet is: TDS = 71000 ppm, TOC = 150 ppm, Ca 2+= 0.5 ppm, F - = 20 ppm, Cl - = 41600 ppm, SO4 2- = 400 ppm, SiO2 = 20 ppm, NO3 - = 310 ppm, water volume is 37.5 m 3 / h. Through the first crystallization treatment, 2 t / h of sodium chloride is produced, and the sodium chloride product meets the first-class standard of industrial dry salt in refined industrial salt of "Industrial Salt" (GB / T 5462 - 2015); the influent water quality of sodium sulfate evaporation crystallization is: TDS = 138500 ppm, TOC = 150 ppm, Ca 2+ = 26 ppm, F - = 35 ppm, Cl - = 13600 ppm, SO4 2- = 77650 ppm, SiO2 = 20 ppm, NO3 - = 125 ppm, water volume is 14.5 m 3 / h. Through the second crystallization treatment, 1.5 t / h of anhydrous sodium sulfate is produced, and the sodium sulfate product meets the standard of Class II qualified products in Table 1 of "Industrial Anhydrous Sodium Sulfate" (GB / T 6009 - 2014).

[0062] It should be noted that, as can be understood by those skilled in the art, the data given throughout the text are only exemplary and not limiting.

[0063] Example Two

[0064] This example provides a zero liquid discharge treatment system for wastewater. Specifically, please refer to Figure 3 , Figure 3 , which is the structural block diagram of a zero liquid discharge treatment system for wastewater provided in this example. It can be seen from Figure 3 that the zero liquid discharge treatment system for wastewater includes:

[0065] The first concentration pretreatment device 100, configured to perform the first concentration pretreatment on the coking wastewater to obtain the first industrial fresh water and the first concentrated water;

[0066] The second concentration pretreatment device 200, configured to perform the second concentration pretreatment on the cold rolling wastewater to obtain the second industrial fresh water and the second concentrated water;

[0067] The concentrated water pretreatment device 300, configured to perform mixed blending according to the water qualities of the power plant desulfurization wastewater, the sintering acid-making wastewater, the first concentrated water and the second concentrated water, and then perform concentrated water pretreatment to obtain the first produced water;

[0068] The membrane separation and concentration treatment device 400 is configured to perform membrane separation and concentration treatment on the first produced water to obtain third industrial fresh water, second produced water, and third concentrated water;

[0069] The first crystallization treatment device 500 is configured to perform first crystallization treatment on the second produced water;

[0070] The second crystallization treatment device 600 is configured to perform second crystallization treatment on the third concentrated water.

[0071] Thus, the zero liquid discharge treatment system provided in this embodiment belongs to the same inventive concept as the zero liquid discharge treatment method described in any of the above embodiments. Therefore, the zero liquid discharge treatment system provided in this embodiment has at least all the advantages of the zero liquid discharge treatment method, which will not be elaborated here.

[0072] In summary, the zero-emission wastewater treatment method and system provided by the present invention have the following advantages: The wastewater includes coking wastewater, cold rolling wastewater, power plant desulfurization wastewater, and sintering acid-making wastewater. The treatment method includes: performing a first concentration pretreatment on the coking wastewater to obtain first industrial fresh water and first concentrated water; performing a second concentration pretreatment on the cold rolling wastewater to obtain second industrial fresh water and second concentrated water; according to the water qualities of the power plant desulfurization wastewater, the sintering acid-making wastewater, the first concentrated water, and the second concentrated water, performing mixing and blending and then performing concentrated water pretreatment to obtain first produced water; performing membrane separation and concentration treatment on the first produced water to obtain third industrial fresh water, second produced water, and third concentrated water; performing a first crystallization treatment on the second produced water; and performing a second crystallization treatment on the third concentrated water. Thus, in the zero-emission wastewater treatment method provided by the present invention, by respectively performing a first concentration pretreatment (exemplarily, including but not limited to a first sand filtration treatment) and a second concentration pretreatment (exemplarily, including but not limited to a second sand filtration treatment) on the coking wastewater and the cold rolling wastewater, most of the suspended solids and microorganisms in the coking wastewater and the cold rolling wastewater can be removed, and the turbidity, colloid, bacteria, and most of the viruses and macromolecular organic matters and other impurities in the coking wastewater and the cold rolling wastewater can be reduced, avoiding blockage of production equipment; by performing mixing and blending according to the water qualities of the power plant desulfurization wastewater, the sintering acid-making wastewater, the first concentrated water, and the second concentrated water and then performing concentrated water pretreatment (exemplarily, including but not limited to defluorination treatment and hardness removal treatment), the characteristics of cations and anions in the wastewater can be utilized to remove fluorine, calcium, magnesium, heavy metals, and organic matters and the like in the wastewater, thereby being able to save chemicals, reduce operation costs, and reduce the influence on the subsequent membrane separation and concentration section and crystallization section; by performing membrane separation and concentration treatment (exemplarily, including but not limited to low-pressure nanofiltration treatment and high-pressure nanofiltration treatment) on the first produced water obtained after concentrated water pretreatment, sodium chloride salts and sodium sulfate salts in the wastewater can be separated and further separated and concentrated, laying a foundation for the subsequent crystallization section; by performing a first crystallization treatment on the second produced water obtained after membrane separation and concentration treatment, sodium chloride crystals meeting industrial standards can be produced; by performing a second crystallization treatment (exemplarily, including but not limited to electrocatalytic oxidation treatment) on the third concentrated water obtained after membrane separation and concentration treatment, the enrichment of organic matters can be reduced, ensuring the produced water quality and the salt quality. The present invention performs a first concentration pretreatment on the coking wastewater to obtain first concentrated water and a second concentration pretreatment on the cold rolling wastewater to obtain second concentrated water, then performs mixing and blending according to the water qualities of the first concentrated water, the second concentrated water, the power plant desulfurization wastewater, and the sintering acid-making wastewater, and then performs concentrated water pretreatment, membrane separation and concentration treatment, first crystallization treatment, and second crystallization treatment. Through wastewater salt extraction, salt and nitrate co-production is achieved, and industrial fresh water is obtained as recycled water, thereby realizing zero-emission of wastewater.

[0073] Further, the concentrated water pretreatment is carried out after mixing and blending according to the water qualities of the desulfurized wastewater of the power plant, the sintering acid-making wastewater, the first concentrated water, and the second concentrated water to obtain the first produced water, including: conveying the desulfurized wastewater of the power plant and the resin acid regeneration wastewater in the acid waste liquid pit to the third regulating tank, conveying the sintering acid-making wastewater to the fourth regulating tank, and conveying the first concentrated water and the second concentrated water to the fifth regulating tank; conveying the wastewater in the third regulating tank, the wastewater in the fourth regulating tank, and the wastewater in the fifth regulating tank to the high-density fluoride removal tank for mixing and fluoride removal treatment; conveying the effluent of the high-density fluoride removal tank, the waste liquid in the high-concentration waste liquid pit, and the resin base regeneration wastewater in the alkaline waste liquid pit to the high-density hardness removal tank for hardness removal treatment; conveying the effluent of the high-density hardness removal tank to the high-density COD removal tank for organic matter removal treatment; performing the third sand filtration treatment, the third ultrafiltration treatment, and the third resin softening treatment on the effluent of the high-density COD removal tank; and obtaining the first produced water after the third resin softening treatment. Thus, for the zero-emission wastewater treatment method provided by the present invention, by setting the third regulating tank, the fourth regulating tank, and the fifth regulating tank, the water quality and water volume of the wastewater can be adjusted to ensure the continuous production of the equipment; by conveying the wastewater in the third regulating tank, the wastewater in the fourth regulating tank, and the wastewater in the fifth regulating tank to the high-density fluoride removal tank for mixing and fluoride removal treatment, the high calcium ion characteristics in the wastewater can be utilized to reduce the fluoride ion concentration, thereby saving chemicals; by conveying the effluent of the high-density fluoride removal tank, the waste liquid in the high-concentration waste liquid pit, and the resin base regeneration wastewater in the alkaline waste liquid pit to the high-density hardness removal tank for hardness removal treatment, the hardness in the water body can be removed, and the waste liquid can be utilized to adjust the pH, thereby saving the chemicals for pH adjustment; by setting the high-density COD removal tank, the organic matter in the wastewater can be removed. Through multi-stage high-density treatment, fluorine, calcium, magnesium, heavy metals, and organic matter in the wastewater can be removed, thereby ensuring the stable operation of the subsequent membrane separation and concentration treatment section and avoiding risks such as subsequent scaling and fouling. By performing the third sand filtration treatment on the effluent of the high-density COD removal tank, the suspended solids in the wastewater can be removed; by the third ultrafiltration treatment, the microorganisms in the wastewater can be removed and the suspended particles in the wastewater can be further removed; by the third resin softening treatment, part of the calcium and magnesium ions in the wastewater can be removed, reducing the hardness in the wastewater.

[0074] Furthermore, after mixing and blending according to the water qualities of the desulfurized wastewater of the power plant, the sintering acid-making wastewater, the first concentrated water, and the second concentrated water, and then performing pretreatment on the concentrated water to obtain the first produced water, it further includes: conveying the highly concentrated backwash water after the third sand filtration treatment and the third ultrafiltration treatment to the highly concentrated waste liquid pit, conveying the resin acid regeneration waste liquid after the third resin softening treatment to the acidic waste liquid pit, and conveying the resin alkali regeneration waste liquid after the third resin softening treatment to the alkaline waste liquid pit. Thus, for the zero-emission wastewater treatment method provided by the present invention, by collecting the waste liquids generated during the wastewater treatment process, and conveying the waste liquids in the highly concentrated waste liquid pit and the alkaline waste liquid pit to the high-density hardening removal tank, and conveying the resin acid regeneration waste liquid in the acidic waste liquid pit to the third adjustment tank, it can save chemicals, thereby laying a foundation for economically and effectively removing the pollutants in the wastewater.

[0075] Since the zero-emission wastewater treatment system provided by the present invention belongs to the same inventive concept as the zero-emission wastewater treatment method described in any one of the above, therefore, the zero-emission wastewater treatment system provided by the present invention at least has all the advantages of the zero-emission wastewater treatment method. Here, it will not be elaborated any further. For more detailed content, please refer to the relevant description of the beneficial effects of the zero-emission wastewater treatment method above.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A zero-emission wastewater treatment method, characterized in that, The wastewater includes coking wastewater, cold rolling wastewater, power plant desulfurization wastewater, and sintering acid-making wastewater. The treatment method includes: Performing a first concentration pretreatment on the coking wastewater to obtain first industrial fresh water and first concentrated water, including the following steps: conveying the coking wastewater to a first regulating tank; sequentially performing a first sand filtration treatment, a first ultrafiltration treatment, a first resin softening treatment, and a first reverse osmosis treatment on the coking wastewater in the first regulating tank; obtaining the first industrial fresh water and the first concentrated water after the first reverse osmosis treatment, and recycling the first industrial fresh water as industrial water; conveying the backwash water after the first sand filtration treatment and the first ultrafiltration treatment to the first regulating tank after precipitation, conveying the resin acid regeneration waste liquid after the first resin softening treatment to an acidic waste liquid pit, and conveying the resin alkali regeneration waste liquid after the first resin softening treatment to an alkaline waste liquid pit; Performing a second concentration pretreatment on the cold rolling wastewater to obtain second industrial fresh water and second concentrated water; According to the water qualities of the power plant desulfurization wastewater, the sintering acid-making wastewater, the first concentrated water, and the second concentrated water, performing mixing and preparation and then performing concentrated water pretreatment to obtain first produced water, including the following steps: conveying the power plant desulfurization wastewater and the resin acid regeneration waste liquid in the acidic waste liquid pit to a third regulating tank, conveying the sintering acid-making wastewater to a fourth regulating tank, and conveying the first concentrated water and the second concentrated water to a fifth regulating tank; conveying the wastewater in the third regulating tank, the wastewater in the fourth regulating tank, and the wastewater in the fifth regulating tank to a defluorination high-density tank for mixing and defluorination treatment; conveying the effluent of the defluorination high-density tank, the waste liquid in the high-concentration waste liquid pit, and the resin alkali regeneration waste liquid in the alkaline waste liquid pit to a dehardening high-density tank for dehardening treatment; conveying the effluent of the dehardening high-density tank to a COD removal high-density tank for organic matter removal treatment; performing a third sand filtration treatment, a third ultrafiltration treatment, and a third resin softening treatment on the effluent of the COD removal high-density tank; obtaining the first produced water after the third resin softening treatment; Performing a membrane separation and concentration treatment on the first produced water to obtain third industrial fresh water, second produced water, and third concentrated water; Performing a first crystallization treatment on the second produced water; Performing a second crystallization treatment on the third concentrated water.

2. The zero-emission wastewater treatment method according to claim 1, characterized in that The performing a second concentration pretreatment on the cold rolling wastewater to obtain second industrial fresh water and second concentrated water includes: Conveying the cold rolling wastewater to a second regulating tank; Sequentially performing a second sand filtration treatment, a second ultrafiltration treatment, a second resin softening treatment, and a second reverse osmosis treatment on the cold rolling wastewater in the second regulating tank; Obtaining the second industrial fresh water and the second concentrated water after the second reverse osmosis treatment, and recycling the second industrial fresh water as industrial water.

3. The zero-emission wastewater treatment method according to claim 2, wherein The performing a second concentration pretreatment on the cold rolling wastewater to obtain second industrial fresh water and second concentrated water further includes: The backwash water after the second sand filtration treatment and the second ultrafiltration treatment is conveyed to the second regulating tank after precipitation, the resin acid regeneration waste liquid after the second resin softening treatment is conveyed to the acidic waste liquid pit, and the resin alkali regeneration waste liquid after the second resin softening treatment is conveyed to the alkaline waste liquid pit.

4. The zero-emission wastewater treatment method according to claim 1, wherein Based on the water qualities of the power plant desulfurization wastewater, the sintering sulfuric acid production wastewater, the first concentrated water, and the second concentrated water, after mixing and blending, pre-treatment of the concentrated water is carried out to obtain the first produced water, and it further includes: The high-concentration backwash water after the third sand filtration treatment and the third ultrafiltration treatment is conveyed to the high-concentration waste liquid pit, the resin acid regeneration waste liquid after the third resin softening treatment is conveyed to the acidic waste liquid pit, and the resin alkali regeneration waste liquid after the third resin softening treatment is conveyed to the alkaline waste liquid pit.

5. The zero-emission wastewater treatment method according to claim 1, characterized in that Carrying out membrane separation and concentration treatment on the first produced water to obtain the third industrial fresh water, the second produced water, and the third concentrated water, including: Conveying the first produced water to a low-pressure nanofiltration inlet tank for low-pressure nanofiltration treatment to obtain the third produced water and the fourth concentrated water; Carrying out high-pressure nanofiltration treatment on the fourth concentrated water to obtain the fourth produced water and the third concentrated water; Carrying out purification nanofiltration treatment on the third produced water and the fourth produced water to obtain the fifth produced water and the fifth concentrated water, and conveying the fifth concentrated water to the low-pressure nanofiltration inlet tank; Carrying out high-pressure reverse osmosis treatment on the fifth produced water to obtain the sixth concentrated water and the third industrial fresh water, and using the third industrial fresh water for industrial water reuse; Conveying the sixth concentrated water to a carbon remover to obtain the sixth produced water; Carrying out tubular microfiltration treatment on the sixth produced water to obtain the second produced water.

6. The zero-emission wastewater treatment method according to claim 1, wherein The first crystallization treatment includes conveying the second produced water to a sodium chloride evaporation crystallization device for evaporation crystallization treatment to obtain sodium chloride crystals and the first mother liquor, conveying the first mother liquor to a miscellaneous salt drying device for drying treatment, and conveying the condensate in the miscellaneous salt drying device to the high-concentration waste liquid pit; The second crystallization treatment includes conveying the third concentrated water to a defluorination sedimentation tank, carrying out fourth sand filtration treatment on the produced water of the defluorination sedimentation tank, carrying out electrocatalytic oxidation treatment on the produced water after the fourth sand filtration treatment, and conveying the produced water after the electrocatalytic oxidation treatment to a sodium sulfate evaporation crystallization device for evaporation crystallization treatment to obtain anhydrous sodium sulfate and the second mother liquor; and carrying out freezing treatment on the second mother liquor to obtain mirabilite crystals and supernatant liquid, dissolving the mirabilite crystals and conveying them to the sodium sulfate evaporation crystallization device, and conveying the supernatant liquid to the high-concentration waste liquid pit.

7. A zero liquid discharge treatment system for wastewater, which adopts the zero liquid discharge treatment method for wastewater according to any one of claims 1 to 6, is characterized in that, The treatment system includes: A first concentration pre-treatment device configured to carry out first concentration pre-treatment on the coking wastewater to obtain the first industrial fresh water and the first concentrated water; A second concentration pre-treatment device configured to carry out second concentration pre-treatment on the cold rolling wastewater to obtain the second industrial fresh water and the second concentrated water; A concentrated water pre-treatment device configured to, based on the water qualities of the power plant desulfurization wastewater, the sintering sulfuric acid production wastewater, the first concentrated water, and the second concentrated water, carry out mixing and blending and then carry out concentrated water pre-treatment to obtain the first produced water; A membrane separation and concentration treatment device, configured to perform membrane separation and concentration treatment on the first produced water to obtain third industrial fresh water, second produced water, and third concentrated water; A first crystallization treatment device, configured to perform first crystallization treatment on the second produced water; A second crystallization treatment device, configured to perform second crystallization treatment on the third concentrated water.

Images