CN113526763A - Resource zero-emission treatment method and treatment system for negative-hardness wastewater - Google Patents
Resource zero-emission treatment method and treatment system for negative-hardness wastewater Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 46
- 150000003839 salts Chemical class 0.000 claims abstract description 501
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims abstract description 120
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- 238000004064 recycling Methods 0.000 claims abstract description 42
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 claims abstract description 25
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- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 3
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- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 description 4
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- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
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- 229910052791 calcium Inorganic materials 0.000 description 2
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 2
- 239000000920 calcium hydroxide Substances 0.000 description 2
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 2
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- 229910052708 sodium Inorganic materials 0.000 description 2
- 229910000885 Dual-phase steel Inorganic materials 0.000 description 1
- 238000003723 Smelting Methods 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 230000003139 buffering effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical group OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
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- 238000006243 chemical reaction Methods 0.000 description 1
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- 230000005494 condensation Effects 0.000 description 1
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- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
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- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
-
- 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
- C02F1/22—Treatment of water, waste water, or sewage by freezing
-
- 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
- C02F1/38—Treatment of water, waste water, or sewage by centrifugal separation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/42—Treatment of water, waste water, or sewage by ion-exchange
-
- 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
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
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- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Water, Waste Water Or Sewage (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
Abstract
The invention provides a zero-emission treatment method and a treatment system for recycling negative hardness wastewater. The invention aims to solve the problems of cost and efficiency of negative hardness wastewater treatment, and uses an ion exchange method to soften the wastewater, thereby avoiding introducing a large amount of chloride ions or sulfate ions, reducing the corrosion resistance grade of zero-discharge system equipment, reducing the energy consumption required for overcoming osmotic pressure, and reducing the medicament adding cost; meanwhile, the influence of a buffer system consisting of carbonate and bicarbonate caused by dosing treatment is avoided, the operation stability of the system is ensured, the bicarbonate is reserved, the sodium carbonate is finally prepared by nanofiltration salt separation, the resource recycling of the sodium carbonate is realized, and the economic benefit is increased.
Description
Technical Field
The invention relates to the technical field of water treatment, in particular to a zero-emission treatment method and a treatment system for recycling negative-hardness wastewater.
Background
With the stricter of the water environmental protection policy in China, enterprises pay more attention to the recycling of waste water step by step, and zero discharge of the waste water frequently appears in the visual field of people. At present, wastewater zero discharge projects frequently fall in industries such as coal chemical industry, electric power, coal, metal smelting and the like. The conventional process route mainly comprises softening pretreatment, concentration and decrement, membrane method/thermal method salt separation and evaporative crystallization, and sodium sulfate and sodium chloride are produced from byproduct salt. The wastewater softening treatment is the primary core unit for resource wastewater zero-discharge treatment, and can slow down scaling pollution of a membrane system or an evaporation system. In the conventional negative-hardness wastewater softening treatment, a large amount of hydrochloric acid or sulfuric acid is added to decompose redundant bicarbonate radicals into carbon dioxide and water, and the carbon dioxide is blown out of a water body; then adding a proper amount of calcium hydroxide or sodium hydroxide to generate calcium carbonate precipitate from calcium ions in the wastewater. The softening treatment method has the advantages of complex process, difficult control of softening effect, incapability of effectively ensuring the stability of the system, high equipment corrosion resistance level, high energy consumption and drug consumption and high operation cost.
The existing treatment of negative hardness wastewater, mainly mine water, has the following defects:
1. because a large amount of hydrochloric acid or sulfuric acid is added to decompose bicarbonate, a large amount of chloride ions or sulfate ions are introduced into the wastewater water body, the salt content of the wastewater is increased, and the corrosion prevention grade of equipment of the zero-discharge system is improved; the energy consumption required for overcoming osmotic pressure is increased; the adding cost of the medicament is high.
2. Because carbonate and bicarbonate form a buffer system, redundant bicarbonate is firstly decomposed, and a proper amount of calcium hydroxide or sodium hydroxide is added to precipitate calcium ions and magnesium ions, the reaction end point and the dosing amount are not easy to accurately control, so that the wastewater is not softened thoroughly, and the zero-discharge system is unstable in operation.
3. Because the treatment process takes the bicarbonate as a pollution factor to decompose, the redundant bicarbonate in the wastewater cannot be recycled.
Therefore, a method and a system for treating negative hardness wastewater with low equipment cost and low system operation cost are needed.
Disclosure of Invention
The invention aims to solve the problems of negative hardness wastewater treatment cost and efficiency, and provides a negative hardness wastewater recycling zero-emission treatment method and a treatment system thereof, wherein an ion exchange method is adopted to soften wastewater, so that a large amount of chloride ions or sulfate ions are prevented from being introduced, the corrosion resistance grade of equipment of a zero-emission system is reduced, the energy consumption required for overcoming osmotic pressure is reduced, and the medicament adding cost is reduced; meanwhile, the influence of a buffer system consisting of carbonate and bicarbonate caused by dosing treatment is avoided, the operation stability of the system is ensured, the bicarbonate is reserved, sodium carbonate is obtained after sodium bicarbonate is calcined by nanofiltration salt separation, the resource recycling of the sodium carbonate is realized, and the economic benefit is increased.
The invention provides a resource zero-emission treatment method for negative hardness wastewater, which comprises the following steps:
s1, softening and concentrating: purifying the negative-hardness wastewater, softening the negative-hardness wastewater by using ion exchange groups in resin, and concentrating and reducing to obtain a softened concentrated solution;
s2, nano-filtration salt separation: nanofiltration is carried out on the softened concentrated solution to separate salt so as to obtain nanofiltration concentrated water and nanofiltration produced water, the nanofiltration concentrated water enters step S4 for treatment, and the nanofiltration produced water enters step S3 for treatment;
s3, nano-filtration water production crystallization: evaporating and crystallizing nanofiltration water product to obtain sodium bicarbonate slurry and a salt side evaporation crystallization mother liquor, freezing and crystallizing the salt side evaporation crystallization mother liquor to obtain the sodium bicarbonate slurry and the salt side freezing crystallization mother liquor, evaporating and crystallizing the salt side freezing crystallization mother liquor to obtain sodium chloride slurry and a sodium chloride evaporation crystallization mother liquor, centrifugally drying the sodium chloride slurry and packaging to obtain a sodium chloride crystal salt finished product, producing mixed salt from the sodium chloride evaporation crystallization mother liquor through a drying system, and treating the sodium bicarbonate slurry in step S5;
s4, nano-filtration concentrated water crystallization: evaporating and crystallizing the nanofiltration concentrated water to obtain sodium bicarbonate slurry and nitrate side evaporation crystallization mother liquor, freezing and crystallizing the nitrate side evaporation crystallization mother liquor to obtain the sodium bicarbonate slurry and nitrate side freezing crystallization mother liquor, evaporating and crystallizing the nitrate side freezing crystallization mother liquor to obtain sodium sulfate slurry and nitrate side sodium sulfate evaporation crystallization mother liquor, centrifuging, drying and packaging the sodium sulfate slurry to obtain a sodium sulfate crystalline salt finished product, evaporating and crystallizing the nitrate side sodium sulfate evaporation mother liquor to obtain mixed salt slurry and mixed salt mother liquor, dissolving the mixed salt slurry back, drying the mixed salt mother liquor to obtain mixed salt, and treating the sodium bicarbonate slurry in step S5;
s5, centrifugal calcination and packaging: and (3) performing centrifugal dehydration and high-temperature calcination on the sodium bicarbonate salt slurry to decompose the sodium bicarbonate salt slurry into sodium carbonate crystalline salt, packaging to obtain a finished product of the sodium carbonate crystalline salt, and completing the resource zero-discharge treatment of the negative hardness wastewater.
The invention relates to a zero emission treatment method for recycling negative hardness wastewater, and as a preferred mode, the step S1 comprises the following steps:
s11, preprocessing: lifting the negative-hardness wastewater to a pretreatment system through a lifting pump to adjust the water quality and water quantity, removing pollution factors such as iron, fluoride and silicon dioxide by a medicament precipitation method, and removing colloid particles, suspended matters and partial organic matters in the wastewater by physical sedimentation and physical interception;
s12, softening: the pretreated wastewater enters a softening system, and ion exchange groups filled with resin in the softening system exchange with calcium and magnesium ions mutually to remove the calcium and magnesium ions in the wastewater and soften the wastewater to obtain softened water and resin regeneration waste liquid;
s13, concentration and decrement: and the softened produced water enters a membrane concentration system for concentration to obtain softened concentrated solution and membrane produced water, and the membrane produced water is collected for reuse.
According to the recycling zero-emission treatment method for negative-hardness wastewater, disclosed by the invention, as a preferred mode, the device for nanofiltration salt separation in the step S2 is a salt separation system, the salt separation system is used for separating monovalent salt and divalent salt in a softened concentrated solution, the nanofiltration concentrated water contains sodium bicarbonate, sodium sulfate and sodium chloride, and the nanofiltration produced water contains sodium bicarbonate, sodium chloride and sodium sulfate.
The invention relates to a zero emission treatment method for recycling negative hardness wastewater, and as a preferred mode, the step S3 comprises the following steps:
s31, sodium bicarbonate on nitro side and evaporation crystallization: lifting the nanofiltration concentrated water to a sodium bicarbonate evaporative crystallization system at a nitrate side through a water pump, and carrying out evaporative crystallization to obtain sodium bicarbonate slurry and a sodium bicarbonate evaporative crystallization mother liquor at the nitrate side, wherein the sodium bicarbonate slurry is conveyed to a sodium bicarbonate centrifugal system and then enters the step S5 for treatment;
s32, freezing and crystallizing sodium bicarbonate on nitre side: lifting the sodium nitrate side evaporation crystallization mother liquor to a sodium nitrate side freezing crystallization system through a water pump, and performing freezing crystallization to obtain sodium bicarbonate slurry and sodium nitrate side freezing crystallization mother liquor, wherein the sodium bicarbonate slurry is conveyed to a sodium bicarbonate centrifugal system and then enters the step S5 for treatment;
s33, evaporation and crystallization of sodium sulfate: lifting the sodium sulfate side frozen crystallization mother liquor to a sodium sulfate evaporation crystallization system through a water pump, and carrying out evaporation crystallization to obtain sodium sulfate slurry and the sodium sulfate side frozen crystallization mother liquor, wherein the sodium sulfate slurry is conveyed to a sodium sulfate centrifugal system for centrifugation and then conveyed to a sodium sulfate drying and packaging system to obtain a sodium sulfate crystal salt finished product;
s34, evaporating and crystallizing miscellaneous salts: and lifting the sodium sulfate evaporative crystallization mother liquor on the nitrate side to a mixed salt evaporative crystallization system through a water pump, and carrying out evaporative crystallization to obtain mixed salt slurry and mixed salt mother liquor, wherein the mixed salt slurry is mixed salt slurry containing sodium sulfate and sodium chloride, the mixed salt slurry is conveyed to a crude salt redissolution system, is redissolved, is conveyed to a water inlet of a salt separation system for circulating salt separation, and the mixed salt mother liquor is lifted to a mixed salt drying system through the water pump, and is dried to obtain mixed salt.
The invention relates to a zero-emission treatment method for recycling negative-hardness wastewater, which is characterized in that in a preferable mode, in step S31, the temperature of sodium bicarbonate evaporative crystallization is 100-110 ℃, and condensate of the sodium bicarbonate evaporative crystallization is collected and recycled;
in the step S32, the temperature of sodium bicarbonate frozen crystallization is 30-50 ℃;
in the step S33, the temperature of sodium sulfate evaporative crystallization is 100-110 ℃, and condensate of the sodium sulfate evaporative crystallization is collected and recycled;
in step S34, the mixed salt slurry may also be sent to a mixed salt drying system to be dried to obtain mixed salt.
The invention relates to a zero emission treatment method for recycling negative hardness wastewater, and as a preferred mode, the step S4 comprises the following steps:
s41, evaporative crystallization of sodium bicarbonate on salt side: lifting the nanofiltration product water to a sodium bicarbonate evaporative crystallization system at a salt side through a water pump, and evaporating and crystallizing to obtain sodium bicarbonate salt slurry and a sodium bicarbonate evaporative crystallization mother liquor at the salt side, wherein the sodium bicarbonate crystallized salt slurry enters a sodium bicarbonate centrifugal system and then is treated in step S5;
s42, freezing and crystallizing sodium bicarbonate on the salt side: lifting the salt side evaporation crystallization mother liquor to a salt side freezing crystallization system through a water pump, and performing freezing crystallization to obtain sodium bicarbonate slurry and salt side freezing crystallization mother liquor, wherein the sodium bicarbonate slurry is conveyed to a sodium bicarbonate centrifugal system and then enters a step S5 for treatment;
s43, sodium chloride evaporation and crystallization: and the salt side frozen crystallization mother liquor is lifted to a sodium chloride evaporative crystallization system through a water pump to obtain sodium chloride salt slurry and sodium chloride evaporative crystallization mother liquor through evaporative crystallization, the sodium chloride salt slurry is conveyed to a sodium chloride centrifugal system for centrifugation and then conveyed to a sodium chloride drying and packaging system to obtain sodium chloride crystal salt, and the sodium chloride evaporative crystallization mother liquor is conveyed to a mixed salt drying system (11) for drying to produce mixed salt. The invention relates to a zero emission treatment method for recycling negative hardness wastewater, and as a preferred mode, the step S5 comprises the following steps:
s51, sodium bicarbonate crystallization and centrifugal dehydration: conveying the sodium bicarbonate crystals to a sodium bicarbonate centrifugal system for centrifugal dehydration to obtain sodium bicarbonate;
s52, sodium bicarbonate calcination: conveying the sodium bicarbonate salt to a sodium bicarbonate calcining system for heating and decomposing to generate sodium carbonate crystal salt;
s53, packaging sodium carbonate: and conveying the sodium carbonate crystal salt to a sodium carbonate packaging system for packaging to obtain a finished product of the sodium carbonate crystal salt.
The invention provides a zero-emission treatment system for recycling negative hardness wastewater, which comprises a pretreatment system, a softening system, a membrane concentration system, a salt separation system, a saltpeter-side sodium bicarbonate evaporative crystallization system connected with a concentrated water outlet of the salt separation system, a saltpeter-side freezing crystallization system connected with a mother liquor outlet of the saltpeter-side sodium bicarbonate evaporative crystallization system, a sodium bicarbonate centrifugal system connected with a salt slurry outlet of the saltpeter-side sodium bicarbonate evaporative crystallization system, a sodium sulfate evaporative crystallization system connected with a mother liquor outlet of the saltpeter-side freezing crystallization system, a miscellaneous salt evaporative crystallization system connected with a mother liquor outlet of the sodium sulfate evaporative crystallization system, a crude salt redissolution system connected with a salt slurry outlet of the miscellaneous salt evaporative crystallization system, a miscellaneous salt drying system connected with a mother liquor outlet of the miscellaneous salt evaporative crystallization system (9), and a sodium sulfate centrifugal system connected with a salt slurry outlet of the sodium sulfate evaporative crystallization system which are connected in sequence, the sodium sulfate drying and packaging system is connected with an outlet of the sodium sulfate centrifugal system, the sodium bicarbonate calcining system is connected with an outlet of the sodium bicarbonate centrifugal system, the sodium carbonate packaging system is connected with an outlet of the sodium bicarbonate calcining system, the salt side sodium bicarbonate evaporative crystallization system is connected with a water production outlet of the salt separation system, the salt side freezing and crystallization system is connected with a mother liquor outlet of the salt side sodium bicarbonate evaporative crystallization system, the sodium chloride evaporative crystallization system is connected with a mother liquor outlet of the salt side freezing and crystallization system, the sodium chloride centrifugal system is connected with a salt slurry outlet of the sodium chloride evaporative crystallization system, and the sodium chloride drying and packaging system is connected with an outlet of the sodium chloride centrifugal system;
the salt slurry outlet of the sodium bicarbonate evaporative crystallization system on the nitrate side, the salt slurry outlet of the freezing crystallization system on the nitrate side, the salt slurry outlet of the sodium bicarbonate evaporative crystallization system on the salt side and the salt slurry outlet of the freezing crystallization system on the salt side are all connected with the inlet of the sodium bicarbonate centrifugal system;
the pretreatment system is used for adjusting the water quality and the water quantity of the negative-hardness wastewater, removing iron, fluoride and silicon dioxide by a medicament precipitation method, and removing colloid particles, suspended matters and partial organic matters in the wastewater by physical sedimentation and physical interception to obtain the pretreatment wastewater;
the softening system is used for enabling ion exchange groups filled with the resin to exchange with calcium ions and magnesium ions in the pretreated wastewater, so that the effects of removing the calcium ions and the magnesium ions in the wastewater and softening the wastewater are achieved, and bicarbonate is reserved at the same time, and softened water and resin regeneration waste liquid are obtained;
the membrane concentration system is used for concentrating and reducing softened produced water so as to enrich and reduce salt, so as to obtain softened concentrated solution and membrane produced water, and the membrane produced water is collected and recycled;
the salt separating system is used for separating monovalent salt and divalent salt in the softened concentrated solution to obtain nanofiltration concentrated water and nanofiltration produced water;
the sodium bicarbonate evaporative crystallization system on the nitre side is used for separating sodium bicarbonate crystal salt from nanofiltration concentrated water through evaporative crystallization to obtain a nitre side evaporative crystallization mother liquor and sodium bicarbonate slurry;
the nitre side freezing crystallization system is used for cooling the nitre side evaporation crystallization mother liquor to further crystallize and separate out sodium bicarbonate in the nitre side evaporation crystallization mother liquor to obtain nitre side freezing crystallization mother liquor and sodium bicarbonate slurry;
the sodium bicarbonate centrifugal system is used for centrifugally dewatering the sodium bicarbonate salt slurry to obtain sodium bicarbonate salt;
the sodium sulfate evaporative crystallization system is used for separating sodium sulfate crystal salt from the sodium nitrate side frozen crystallization mother liquor through evaporative crystallization to obtain sodium sulfate slurry and sodium sulfate evaporative crystallization mother liquor on the sodium nitrate side;
the mixed salt evaporative crystallization system is used for separating sodium sulfate and sodium chloride mixed crystallization salt by carrying out evaporative crystallization on sodium sulfate evaporative crystallization mother liquor on the nitrate side to obtain mixed salt slurry and mixed salt mother liquor;
the crude salt redissolution system comprises a redissolution water tank and a lifting water pump which are connected, and is used for redissolving mixed salt slurry containing mixed crystal salt and then conveying the redissolved mixed salt slurry to a water inlet of the salt separation system for circulating salt separation, wherein the mixed crystal salt is mixed crystal salt of sodium sulfate and sodium chloride;
the mixed salt drying system is used for drying the mixed salt mother liquor and/or the sodium chloride evaporation crystallization mother liquor by utilizing high-temperature steam to produce mixed salt;
the sodium sulfate centrifugal system is used for centrifugally dewatering the sodium sulfate salt slurry to obtain sodium sulfate crystal salt;
the sodium sulfate drying and packaging system is used for drying and packaging the sodium sulfate crystalline salt to obtain a finished product of the sodium sulfate crystalline salt;
the sodium bicarbonate calcining system is used for calcining sodium bicarbonate to obtain sodium carbonate crystal salt;
the sodium carbonate packaging system is used for packaging the sodium carbonate crystalline salt to obtain an industrial finished product of the sodium carbonate crystalline salt;
the salt side sodium bicarbonate evaporative crystallization system is used for separating sodium bicarbonate from nanofiltration water produced by sodium bicarbonate, sodium chloride and sodium sulfate through evaporative crystallization to obtain sodium bicarbonate salt slurry and salt side evaporative crystallization mother liquor, wherein the salt side evaporative crystallization mother liquor contains sodium bicarbonate, sodium sulfate and sodium chloride which are not separated through crystallization;
the salt side freezing and crystallizing system is used for cooling the salt side evaporation and crystallization mother liquor to further crystallize and separate out sodium bicarbonate in the salt side evaporation and crystallization mother liquor to obtain sodium bicarbonate salt slurry and the salt side freezing and crystallization mother liquor;
the sodium chloride evaporative crystallization system is used for carrying out evaporative crystallization on the salt side frozen crystallization mother liquor to separate out sodium chloride crystal salt to obtain sodium chloride salt slurry and sodium chloride evaporative crystallization mother liquor;
the sodium chloride centrifugal system is used for carrying out centrifugal dehydration on the sodium chloride salt slurry to obtain sodium chloride crystal salt;
the sodium chloride drying and packaging system is used for packaging the sodium chloride crystal salt to obtain sodium chloride finished salt.
According to the recycling zero-emission treatment system for negative-hardness wastewater, which is disclosed by the invention, as an optimal mode, a water outlet of the mixed salt redissolution system is connected with a water inlet of the salt separation system.
The invention relates to a zero-emission treatment system for recycling negative hardness wastewater, which is characterized in that as an optimal mode, a pretreatment system is any one or more of the following: the device comprises a regulating tank, a high-density sedimentation tank, a V-shaped filter tank, a valveless filter tank, a manganese sand filter and a multi-media filter;
the softening system is an ion exchange device and is filled with weak acid type cation exchange resin;
the membrane concentration system is any one or more of the following systems: self-cleaning filter, ultrafiltration device, reverse osmosis unit, high pressure reverse osmosis unit and electrodialysis device.
The negative hardness wastewater is lifted to a pretreatment system through a water pump, the effects of adjusting the water quality and the water quantity and removing colloid particles, suspended matters and partial organic matters in the wastewater are achieved, and the pretreatment system comprises treatment facilities such as a regulating tank, a sedimentation tank, a filter tank and a filter. The water produced by the pretreatment system is lifted to a softening system through a water pump, the effect of removing calcium and magnesium ions in the wastewater and simultaneously retaining bicarbonate is achieved, the softening system is an ion exchange system, and cation exchange resin is adopted. The water produced by the softening system is lifted to a membrane concentration system through a water pump to play a role in concentration and reduction, and the membrane concentration system comprises treatment facilities such as ultrafiltration, reverse osmosis and electrodialysis. The produced water of the membrane concentration system is recycled after being collected, the concentrated water of the membrane concentration system is lifted to the salt separation system through a water pump to play a role in separating the primary salt and the divalent salt, and the salt separation system adopts a nanofiltration membrane.
And (3) lifting the concentrated water of the salt separation system to a sodium bicarbonate evaporation crystallization system at a nitrate side through a water pump, crystallizing and separating out sodium bicarbonate, controlling the temperature at 100-110 ℃, collecting and recycling the condensate, and conveying the sodium bicarbonate slurry to a sodium bicarbonate centrifugal system. And lifting the mother liquor of the sodium bicarbonate evaporation and crystallization system at the nitre side to a sodium bicarbonate freezing and crystallization system through a water pump, crystallizing and separating out sodium bicarbonate, controlling the temperature at 30-50 ℃, and conveying the sodium bicarbonate slurry to a sodium bicarbonate centrifugal system. Lifting the mother liquor of the sodium sulfate side freezing crystallization system to a sodium sulfate evaporation crystallization system through a water pump, crystallizing to separate out sodium sulfate, controlling the temperature at 100-110 ℃, collecting and recycling condensed liquid, conveying sodium sulfate slurry to a sodium sulfate centrifugal system, conveying the centrifuged sodium sulfate to a sodium sulfate drying and packaging system, and finally producing sodium sulfate crystallized salt, wherein the sodium sulfate crystallized salt reaches first-class products of the physicochemical index I of industrial sodium sulfate, and the purity is more than or equal to 99.0%;
lifting mother liquor of the sodium sulfate evaporation crystallization system to a mixed salt evaporation crystallization system through a water pump, crystallizing and separating out mixed salt containing a large amount of sodium chloride, controlling the temperature at 100-110 ℃, collecting and recycling condensed liquid, conveying mixed salt slurry to a mixed salt redissolution system, and conveying the redissolved mixed salt solution to the front end of a salt separation system for circulating salt separation; and lifting the mother liquor of the mixed salt evaporation crystallization system to a mixed salt drying system through a water pump, drying and producing the mixed salt.
And (3) lifting the produced water of the salt separation system to a sodium bicarbonate evaporation crystallization system at the salt side through a water pump, crystallizing and separating out sodium bicarbonate, controlling the temperature at 100-110 ℃, collecting and recycling condensate, and conveying sodium bicarbonate slurry to a sodium bicarbonate centrifugal system. And lifting the mother liquor of the salt side sodium bicarbonate evaporation crystallization system to a salt side freezing crystallization system through a water pump, crystallizing and separating out sodium bicarbonate, controlling the temperature at 30-50 ℃, and conveying the sodium bicarbonate slurry to a sodium bicarbonate centrifugal system. And (3) lifting the mother liquor of the salt side freezing crystallization system to a sodium chloride evaporation crystallization system through a water pump, crystallizing to separate out sodium chloride, controlling the temperature at 100-110 ℃, collecting condensate for recycling, conveying sodium chloride slurry to a sodium chloride centrifugal system, conveying the centrifuged sodium chloride to a sodium chloride drying and packaging system, and finally producing sodium chloride crystal salt, wherein the sodium chloride industrial dry salt secondary quality is achieved, and the purity is more than or equal to 97.5%.
Sodium bicarbonate slurry crystallized and separated by a sodium nitrate side sodium bicarbonate evaporative crystallization system, a sodium nitrate side freezing crystallization system, a salt side sodium bicarbonate evaporative crystallization system and a salt side freezing crystallization system is conveyed to a sodium bicarbonate centrifugal system, the sodium bicarbonate subjected to centrifugal dehydration is conveyed to a sodium bicarbonate calcining system, the temperature is controlled at 270 ℃, the sodium bicarbonate is heated and decomposed to generate sodium carbonate, the sodium carbonate is conveyed to a sodium carbonate packaging system, and finally sodium carbonate crystal salt is produced, so that the industrial sodium carbonate salt physicochemical index II qualified product is achieved, and the purity is more than or equal to 98.0%.
And the sodium carbonate crystal salt part is used for treating calcium-containing regeneration waste liquid generated by a salt separation system, and the rest is sold.
The invention has the following advantages:
(1) the waste water is softened by adopting an ion exchange method, so that a large amount of chloride ions or sulfate ions are prevented from being introduced, and the corrosion resistance grade of equipment of a zero-discharge system can be reduced; the energy consumption for overcoming osmotic pressure is reduced; the adding cost of the medicament is reduced.
(2) The ion exchange method is adopted to soften the wastewater, so that the influence caused by a buffer system consisting of carbonate and bicarbonate caused by dosing treatment is avoided, and the running stability of the system is ensured.
(3) The bicarbonate is reserved, the sodium carbonate is prepared, the resource recycling of the sodium carbonate is realized, and the economic benefit is increased.
Drawings
FIG. 1 is a flow chart of a zero-emission treatment method for recycling negative-hardness wastewater;
FIG. 2 is a flowchart of step S1 of a zero discharge treatment method for recycling negative hardness wastewater;
FIG. 3 is a flowchart of step S3 of a zero discharge treatment method for recycling negative hardness wastewater;
FIG. 4 is a flowchart of step S4 of a zero discharge treatment method for recycling negative hardness wastewater;
FIG. 5 is a flowchart of step S5 of a zero discharge treatment method for recycling negative hardness wastewater;
FIG. 6 is a schematic view of a negative hardness wastewater recycling zero-emission treatment system.
Reference numerals:
1. a pre-treatment system; 2. a softening system; 3. a membrane concentration system; 4. a salt separation system; 5. sodium bicarbonate evaporative crystallization system on nitre side; 6. a nitre side freezing and crystallizing system; 7. a sodium bicarbonate centrifugation system; 8. sodium sulfate evaporative crystallization system; 9. a miscellaneous salt evaporation crystallization system; 10. a crude salt redissolution system; 11. a miscellaneous salt drying system; 12. a sodium sulfate centrifugation system; 13. a sodium sulfate drying and packaging system; 14. a sodium bicarbonate calcination system; 15. a sodium carbonate packaging system; 16. a salt side sodium bicarbonate evaporative crystallization system; 17. a salt side freezing crystallization system; 18. a sodium chloride evaporative crystallization system; 19. a sodium chloride centrifugation system; 20. sodium chloride drying and packaging system.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.
Example 1
As shown in fig. 1, a zero-emission treatment method for recycling negative-hardness wastewater comprises the following steps:
s1, softening and concentrating: purifying the negative-hardness wastewater, softening the negative-hardness wastewater by using ion exchange groups in resin, and concentrating and reducing to obtain a softened concentrated solution;
s2, nano-filtration salt separation: nanofiltration is carried out on the softened concentrated solution to separate salt so as to obtain nanofiltration concentrated water and nanofiltration produced water, the nanofiltration concentrated water enters step S4 for treatment, and the nanofiltration produced water enters step S3 for treatment;
s3, nano-filtration water production crystallization: evaporating and crystallizing nanofiltration water product to obtain sodium bicarbonate slurry and a salt side evaporation crystallization mother liquor, freezing and crystallizing the salt side evaporation crystallization mother liquor to obtain the sodium bicarbonate slurry and the salt side freezing crystallization mother liquor, evaporating and crystallizing the salt side freezing crystallization mother liquor to obtain sodium chloride slurry and a sodium chloride evaporation crystallization mother liquor, centrifugally drying the sodium chloride slurry and packaging to obtain a sodium chloride crystal salt finished product, producing mixed salt from the sodium chloride evaporation crystallization mother liquor through a drying system, and treating the sodium bicarbonate slurry in step S5;
s4, nano-filtration concentrated water crystallization: evaporating and crystallizing the nanofiltration concentrated water to obtain sodium bicarbonate slurry and nitrate side evaporation crystallization mother liquor, freezing and crystallizing the nitrate side evaporation crystallization mother liquor to obtain the sodium bicarbonate slurry and nitrate side freezing crystallization mother liquor, evaporating and crystallizing the nitrate side freezing crystallization mother liquor to obtain sodium sulfate slurry and nitrate side sodium sulfate evaporation crystallization mother liquor, centrifuging, drying and packaging the sodium sulfate slurry to obtain a sodium sulfate crystalline salt finished product, evaporating and crystallizing the nitrate side sodium sulfate evaporation mother liquor to obtain mixed salt slurry and mixed salt mother liquor, dissolving the mixed salt slurry back, drying the mixed salt mother liquor to obtain mixed salt, and treating the sodium bicarbonate slurry in step S5; s5, centrifugal calcination and packaging: and (3) performing centrifugal dehydration and high-temperature calcination on the sodium bicarbonate salt slurry to decompose the sodium bicarbonate salt slurry into sodium carbonate crystalline salt, packaging to obtain a finished product of the sodium carbonate crystalline salt, and completing the resource zero-discharge treatment of the negative hardness wastewater.
Example 2
As shown in fig. 1, a zero-emission treatment method for recycling negative-hardness wastewater comprises the following steps:
s1, softening and concentrating: purifying the negative-hardness wastewater, softening the negative-hardness wastewater by using ion exchange groups in resin, and concentrating and reducing to obtain a softened concentrated solution;
as shown in fig. 2, S11, preprocessing: lifting the negative-hardness wastewater to a pretreatment system 1 through a lifting pump to adjust the water quality and water quantity, removing pollution factors such as iron, fluoride and silicon dioxide by a medicament precipitation method, and removing colloid particles, suspended matters and partial organic matters in the wastewater by physical sedimentation and physical interception to obtain pretreated wastewater;
s12, softening: the pretreated wastewater enters a softening system 2, and ion exchange groups filled with resin in the softening system 2 exchange with calcium and magnesium ions mutually to achieve the effects of removing the calcium and magnesium ions in the wastewater and softening the wastewater, so as to obtain softened product water and resin regeneration waste liquid;
s13, concentration and decrement: the softened produced water enters a membrane concentration system 3 for concentration to obtain softened concentrated solution and membrane produced water, and the membrane produced water is collected for reuse.
S2, nano-filtration salt separation: nanofiltration is carried out on the softened concentrated solution to separate salt so as to obtain nanofiltration concentrated water and nanofiltration produced water, the nanofiltration concentrated water enters step S4 for treatment, and the nanofiltration produced water enters step S3 for treatment;
the nanofiltration salt separation device is a salt separation system 4, the salt separation system 4 is used for separating monovalent salt and divalent salt in the softened concentrated solution, the nanofiltration concentrated solution contains a large amount of sodium bicarbonate, sodium sulfate and sodium chloride, and the nanofiltration product water contains a large amount of sodium bicarbonate, sodium chloride and trace sodium sulfate;
s3, nano-filtration water production crystallization: : evaporating and crystallizing nanofiltration water product to obtain sodium bicarbonate slurry and a salt side evaporation crystallization mother liquor, freezing and crystallizing the salt side evaporation crystallization mother liquor to obtain the sodium bicarbonate slurry and the salt side freezing crystallization mother liquor, evaporating and crystallizing the salt side freezing crystallization mother liquor to obtain sodium chloride slurry and a sodium chloride evaporation crystallization mother liquor, centrifugally drying the sodium chloride slurry and packaging to obtain a sodium chloride crystal salt finished product, producing mixed salt from the sodium chloride evaporation crystallization mother liquor through a drying system, and treating the sodium bicarbonate slurry in step S5; as shown in fig. 3, S31, nitro side sodium bicarbonate, was crystallized by evaporation: lifting the nanofiltration concentrated water to a sodium bicarbonate evaporative crystallization system 5 at a nitrate side through a water pump, and carrying out evaporative crystallization to obtain sodium bicarbonate slurry and a sodium bicarbonate evaporative crystallization mother liquor at the nitrate side, wherein the sodium bicarbonate slurry is conveyed to a sodium bicarbonate centrifugal system 7 and then enters a step S5 for treatment; the temperature of sodium bicarbonate evaporative crystallization is 100-110 ℃, and condensate of the sodium bicarbonate evaporative crystallization is collected and recycled;
s32, freezing and crystallizing sodium bicarbonate on nitre side: lifting the sodium nitrate side evaporation crystallization mother liquor to a sodium nitrate side freezing crystallization system 6 through a water pump, and performing freezing crystallization to obtain sodium bicarbonate slurry and sodium nitrate side freezing crystallization mother liquor, wherein the sodium bicarbonate slurry is conveyed to a sodium bicarbonate centrifugal system 7 and then enters the step S5 for treatment; the temperature of sodium bicarbonate freezing crystallization is 30-50 ℃;
s33, evaporation and crystallization of sodium sulfate: lifting the sodium sulfate side frozen crystallization mother liquor to a sodium sulfate evaporative crystallization system 8 through a water pump, and carrying out evaporative crystallization to obtain sodium sulfate slurry and the sodium sulfate side frozen crystallization mother liquor, wherein the sodium sulfate slurry is conveyed to a sodium sulfate centrifugal system 12 for centrifugation and then conveyed to a sodium sulfate drying and packaging system 13 to obtain a sodium sulfate crystal salt finished product; the temperature of the sodium sulfate evaporative crystallization is 100-110 ℃, and the condensate of the sodium sulfate evaporative crystallization is collected and recycled;
s34, evaporating and crystallizing miscellaneous salts: lifting the sodium sulfate evaporative crystallization mother liquor on the nitrate side to a mixed salt evaporative crystallization system 9 through a water pump, and carrying out evaporative crystallization to obtain mixed salt slurry and mixed salt mother liquor, wherein the mixed salt slurry is mixed salt slurry containing sodium sulfate and sodium chloride, the mixed salt slurry is conveyed to a crude salt redissolution system 10, is redissolved, is conveyed to a water inlet of a salt separation system 4, and is subjected to circulating salt separation, and the mixed salt mother liquor is lifted to a mixed salt drying system 11 through the water pump, and is dried to obtain mixed salt; the mixed salt slurry can also be conveyed to a mixed salt drying system 11 to be dried to obtain mixed salt;
s4, nano-filtration concentrated water crystallization: evaporating and crystallizing the nanofiltration concentrated water to obtain sodium bicarbonate slurry and nitrate side evaporation crystallization mother liquor, freezing and crystallizing the nitrate side evaporation crystallization mother liquor to obtain the sodium bicarbonate slurry and nitrate side freezing crystallization mother liquor, evaporating and crystallizing the nitrate side freezing crystallization mother liquor to obtain sodium sulfate slurry and nitrate side sodium sulfate evaporation crystallization mother liquor, centrifuging, drying and packaging the sodium sulfate slurry to obtain a sodium sulfate crystalline salt finished product, evaporating and crystallizing the nitrate side sodium sulfate evaporation mother liquor to obtain mixed salt slurry and mixed salt mother liquor, dissolving the mixed salt slurry back, drying the mixed salt mother liquor to obtain mixed salt, and treating the sodium bicarbonate slurry in step S5;
as shown in fig. 4, S41, salt side sodium bicarbonate evaporative crystallization: lifting the nanofiltration product water to a sodium bicarbonate evaporative crystallization system 16 on a salt side through a water pump, and carrying out evaporative crystallization to obtain sodium bicarbonate salt slurry and a sodium bicarbonate evaporative crystallization mother liquor on the salt side, wherein the sodium bicarbonate crystallized salt slurry enters a step S5 for treatment after reaching a sodium bicarbonate centrifugal system 7;
s42, freezing and crystallizing sodium bicarbonate on the salt side: lifting the salt side evaporation crystallization mother liquor to a salt side freezing crystallization system 17 through a water pump, and performing freezing crystallization to obtain sodium bicarbonate slurry and salt side freezing crystallization mother liquor, wherein the sodium bicarbonate slurry is conveyed to a sodium bicarbonate centrifugal system 7 and then enters a step S5 for treatment;
s43, sodium chloride evaporation and crystallization: the salt side frozen crystallization mother liquor is lifted to a sodium chloride evaporative crystallization system 18 through a water pump to obtain sodium chloride salt slurry and sodium chloride evaporative crystallization mother liquor through evaporative crystallization, the sodium chloride salt slurry is conveyed to a sodium chloride centrifugal system 19 for centrifugation and then conveyed to a sodium chloride drying and packaging system 20 to obtain sodium chloride crystal salt, and the sodium chloride evaporative crystallization mother liquor is conveyed to a mixed salt drying system (11) for drying to produce mixed salt. S5, centrifugal calcination and packaging: carrying out centrifugal dehydration and high-temperature calcination on the sodium bicarbonate salt slurry to decompose the sodium bicarbonate salt slurry into sodium carbonate crystalline salt, and then packaging to obtain a finished product of the sodium carbonate crystalline salt, wherein the resource zero-discharge treatment of the negative-hardness wastewater is completed;
as shown in fig. 5, S51, sodium bicarbonate crystals were centrifuged: conveying the sodium bicarbonate crystals to a sodium bicarbonate centrifugal system 7 for centrifugal dehydration to obtain sodium bicarbonate;
s52, sodium bicarbonate calcination: conveying the sodium bicarbonate salt to a sodium bicarbonate calcining system 14 for heating and decomposing to generate sodium carbonate crystal salt;
s53, packaging sodium carbonate: and conveying the sodium carbonate crystal salt to a sodium carbonate packaging system 15 for packaging to obtain a finished product of the sodium carbonate crystal salt.
Example 3
As shown in fig. 6, a zero-emission treatment system for recycling negative hardness wastewater comprises a pretreatment system 1, a softening system 2, a membrane concentration system 3, a salt separation system 4, a saltpeter-side sodium bicarbonate evaporative crystallization system 5 connected with a concentrated water outlet of the salt separation system 4, a saltpeter-side freezing crystallization system 6 connected with a mother liquor outlet of the saltpeter-side sodium bicarbonate evaporative crystallization system 5, a sodium bicarbonate centrifugal system 7 connected with a salt slurry outlet of the saltpeter-side sodium bicarbonate evaporative crystallization system 5, a sodium sulfate evaporative crystallization system 8 connected with a mother liquor outlet of the saltpeter-side freezing crystallization system 6, a miscellaneous salt evaporative crystallization system 9 connected with a mother liquor outlet of the sodium sulfate evaporative crystallization system 8, a crude salt redissolution system 10 connected with a salt slurry outlet of the miscellaneous salt evaporative crystallization system 9, and a miscellaneous salt drying system 11 connected with a mother liquor outlet of the miscellaneous salt evaporative crystallization system 9, a sodium sulfate centrifugal system 12 connected with a salt slurry outlet of the sodium sulfate evaporative crystallization system 8, a sodium sulfate drying and packaging system 13 connected with an outlet of the sodium sulfate centrifugal system 12, a sodium bicarbonate calcining system 14 connected with an outlet of the sodium bicarbonate centrifugal system 7, a sodium carbonate packaging system 15 connected with an outlet of the sodium bicarbonate calcining system 14, a salt side sodium bicarbonate evaporative crystallization system 16 connected with a water production outlet of the salt separation system 4, a salt side freezing crystallization system 17 connected with a mother liquor outlet of the salt side sodium bicarbonate evaporative crystallization system 16, a sodium chloride evaporative crystallization system 18 connected with a mother liquor outlet of the salt side freezing crystallization system 17, a sodium chloride centrifugal system 19 connected with a salt slurry outlet of the sodium chloride evaporative crystallization system 18, and a sodium chloride drying and packaging system 20 connected with an outlet of the sodium chloride centrifugal system 19;
a salt slurry outlet of the sodium bicarbonate evaporative crystallization system 5 at the nitrate side, a salt slurry outlet of the freezing crystallization system 6 at the nitrate side, a salt slurry outlet of the sodium bicarbonate evaporative crystallization system 16 at the salt side and a salt slurry outlet of the freezing crystallization system 17 at the salt side are all connected with an inlet of a sodium bicarbonate centrifugal system 7;
the pretreatment system 1 is used for adjusting the water quality and the water quantity of the negative hardness wastewater, removing iron, fluoride and silicon dioxide by a medicament precipitation method, and removing colloidal particles, suspended matters and partial organic matters in the wastewater by physical sedimentation and physical interception to obtain the pretreatment wastewater;
the softening system 2 is used for enabling ion exchange groups filled with resin to exchange with calcium ions and magnesium ions in the pretreated wastewater, so as to achieve the effects of removing the calcium ions and the magnesium ions in the wastewater and softening the wastewater, and simultaneously reserving bicarbonate to obtain softened water and resin regeneration waste liquid;
the membrane concentration system 3 is used for concentrating and reducing softened produced water so as to enrich and reduce salt, so as to obtain softened concentrated solution and membrane produced water, and the membrane produced water is collected and recycled;
the salt separating system 4 is used for separating monovalent salt and divalent salt in the softened concentrated solution to obtain nanofiltration concentrated water and nanofiltration produced water;
the sodium bicarbonate evaporative crystallization system 5 on the nitrate side is used for separating sodium bicarbonate crystal salt from nanofiltration concentrated water through evaporative crystallization to obtain mother liquor of sodium bicarbonate evaporative crystallization and sodium bicarbonate slurry;
the nitre side freezing and crystallizing system 6 is used for cooling the nitre side evaporation and crystallization mother liquor to further crystallize and separate out sodium bicarbonate in the nitre side evaporation and crystallization mother liquor so as to obtain nitre side freezing and crystallization mother liquor and sodium bicarbonate slurry;
the sodium bicarbonate centrifugal system 7 is used for centrifugally dewatering the sodium bicarbonate salt slurry to obtain sodium bicarbonate salt;
the sodium sulfate evaporative crystallization system 8 is used for separating sodium sulfate crystal salt from the sodium nitrate side frozen crystallization mother liquor through evaporative crystallization to obtain sodium sulfate slurry and sodium sulfate evaporative crystallization mother liquor on the sodium nitrate side;
the mixed salt evaporative crystallization system 9 is used for separating sodium sulfate and sodium chloride mixed crystallization salt by carrying out evaporative crystallization on sodium sulfate evaporative crystallization mother liquor on the nitrate side to obtain mixed salt slurry and mixed salt mother liquor;
the crude salt redissolution system 10 comprises a redissolution water tank and a lift water pump which are connected, the crude salt redissolution system 10 is used for redissolving mixed salt slurry containing mixed crystal salt, and then conveying the mixed salt slurry to a water inlet of the salt separation system 4 for circulating salt separation, and the mixed crystal salt is mixed crystal salt of sodium sulfate and sodium chloride;
the mixed salt drying system 11 is used for drying the mixed salt mother liquor and/or the sodium chloride evaporation crystallization mother liquor by using high-temperature steam to produce mixed salt;
the sodium sulfate centrifugal system 12 is used for centrifugally dewatering the sodium sulfate salt slurry to obtain sodium sulfate crystal salt;
the sodium sulfate drying and packaging system 13 is used for drying and packaging the sodium sulfate crystalline salt to obtain a finished product of the sodium sulfate crystalline salt;
the sodium bicarbonate calcining system 14 is used for calcining sodium bicarbonate to obtain sodium carbonate crystalline salt;
the sodium carbonate packaging system 15 is used for packaging the sodium carbonate crystalline salt to obtain a sodium carbonate crystalline salt industrial finished product;
the salt side sodium bicarbonate evaporative crystallization system 16 is used for separating sodium bicarbonate from nanofiltration water produced by nanofiltration and containing a large amount of sodium bicarbonate, sodium chloride and a trace amount of sodium sulfate through evaporative crystallization to obtain sodium bicarbonate salt slurry and a salt side evaporative crystallization mother liquor, wherein the salt side evaporative crystallization mother liquor contains sodium bicarbonate, sodium sulfate and sodium chloride which are not separated through crystallization;
the salt side freezing and crystallizing system 17 is used for cooling the salt side evaporation and crystallization mother liquor to further crystallize and separate out sodium bicarbonate in the salt side evaporation and crystallization mother liquor so as to obtain sodium bicarbonate salt slurry and the salt side freezing and crystallization mother liquor;
the sodium chloride evaporative crystallization system 18 is used for evaporating and crystallizing the salt side frozen crystallization mother liquor to separate out sodium chloride crystal salt, so as to obtain sodium chloride salt slurry and sodium chloride evaporative crystallization mother liquor;
the sodium chloride centrifugal system 19 is used for carrying out centrifugal dehydration on the sodium chloride salt slurry to obtain sodium chloride crystal salt;
the sodium chloride drying and packaging system 20 is used for packaging the sodium chloride crystal salt to obtain sodium chloride finished salt.
Example 4
As shown in fig. 6, a zero-emission treatment system for recycling negative hardness wastewater comprises a pretreatment system 1, a softening system 2, a membrane concentration system 3, a salt separation system 4, a saltpeter-side sodium bicarbonate evaporative crystallization system 5 connected with a concentrated water outlet of the salt separation system 4, a saltpeter-side freezing crystallization system 6 connected with a mother liquor outlet of the saltpeter-side sodium bicarbonate evaporative crystallization system 5, a sodium bicarbonate centrifugal system 7 connected with a salt slurry outlet of the saltpeter-side sodium bicarbonate evaporative crystallization system 5, a sodium sulfate evaporative crystallization system 8 connected with a mother liquor outlet of the saltpeter-side freezing crystallization system 6, a miscellaneous salt evaporative crystallization system 9 connected with a mother liquor outlet of the sodium sulfate evaporative crystallization system 8, a crude salt redissolution system 10 connected with a salt slurry outlet of the miscellaneous salt evaporative crystallization system 9, and a miscellaneous salt drying system 11 connected with a mother liquor outlet of the miscellaneous salt evaporative crystallization system 9, a sodium sulfate centrifugal system 12 connected with a salt slurry outlet of the sodium sulfate evaporative crystallization system 8, a sodium sulfate drying and packaging system 13 connected with an outlet of the sodium sulfate centrifugal system 12, a sodium bicarbonate calcining system 14 connected with an outlet of the sodium bicarbonate centrifugal system 7, a sodium carbonate packaging system 15 connected with an outlet of the sodium bicarbonate calcining system 14, a salt side sodium bicarbonate evaporative crystallization system 16 connected with a water production outlet of the salt separation system 4, a salt side freezing crystallization system 17 connected with a mother liquor outlet of the salt side sodium bicarbonate evaporative crystallization system 16, a sodium chloride evaporative crystallization system 18 connected with a mother liquor outlet of the salt side freezing crystallization system 17, a sodium chloride centrifugal system 19 connected with a salt slurry outlet of the sodium chloride evaporative crystallization system 18, and a sodium chloride drying and packaging system 20 connected with an outlet of the sodium chloride centrifugal system 19;
a salt slurry outlet of the sodium bicarbonate evaporative crystallization system 5 at the nitrate side, a salt slurry outlet of the freezing crystallization system 6 at the nitrate side, a salt slurry outlet of the sodium bicarbonate evaporative crystallization system 16 at the salt side and a salt slurry outlet of the freezing crystallization system 17 at the salt side are all connected with an inlet of a sodium bicarbonate centrifugal system 7;
the pretreatment system 1 can be any one or more of the following: the device comprises a regulating tank, a high-density sedimentation tank, a V-shaped filter tank, a valveless filter tank, a manganese sand filter and a multi-media filter;
the pretreatment system 1 is used for adjusting the water quality and the water quantity of the negative hardness wastewater, removing iron, fluoride and silicon dioxide by a medicament precipitation method, and removing colloidal particles, suspended matters and partial organic matters in the wastewater by physical sedimentation and physical interception to obtain the pretreatment wastewater;
the softening system 2 is an ion exchange device, and the softening system 2 is filled with weak acid type cation exchange resin;
the softening system 2 is used for enabling ion exchange groups filled with resin to exchange with calcium ions and magnesium ions in the pretreated wastewater, so as to achieve the effects of removing the calcium ions and the magnesium ions in the wastewater and softening the wastewater, and simultaneously reserving bicarbonate to obtain softened water and resin regeneration waste liquid;
the membrane concentration system 3 is any one or more of the following: a self-cleaning filter, an ultrafiltration device, a reverse osmosis device, a high-pressure reverse osmosis device and an electrodialysis device;
the membrane concentration system 3 is used for concentrating and reducing softened produced water so as to enrich and reduce salt, so as to obtain softened concentrated solution and membrane produced water, and the membrane produced water is collected and recycled;
the salt separating system 4 is used for separating monovalent salt and divalent salt in the softened concentrated solution to obtain nanofiltration concentrated water and nanofiltration produced water;
the sodium bicarbonate evaporative crystallization system 5 on the nitrate side is used for separating sodium bicarbonate crystal salt from nanofiltration concentrated water through evaporative crystallization to obtain mother liquor of sodium bicarbonate evaporative crystallization and sodium bicarbonate slurry;
the nitre side freezing and crystallizing system 6 is used for cooling the nitre side evaporation and crystallization mother liquor to further crystallize and separate out sodium bicarbonate in the nitre side evaporation and crystallization mother liquor so as to obtain nitre side freezing and crystallization mother liquor and sodium bicarbonate slurry;
the sodium bicarbonate centrifugal system 7 is used for centrifugally dewatering the sodium bicarbonate salt slurry to obtain sodium bicarbonate salt;
the sodium sulfate evaporative crystallization system 8 is used for separating sodium sulfate crystal salt from the sodium nitrate side frozen crystallization mother liquor through evaporative crystallization to obtain sodium sulfate slurry and sodium sulfate evaporative crystallization mother liquor on the sodium nitrate side;
the mixed salt evaporative crystallization system 9 is used for separating sodium sulfate and sodium chloride mixed crystallization salt by carrying out evaporative crystallization on sodium sulfate evaporative crystallization mother liquor on the nitrate side to obtain mixed salt slurry and mixed salt mother liquor;
the water outlet of the mixed salt redissolution system 9 is connected with the water inlet of the salt separating system 4;
the crude salt redissolution system 10 comprises a redissolution water tank and a lift water pump which are connected, the crude salt redissolution system 10 is used for redissolving mixed salt slurry containing mixed crystal salt, and then conveying the mixed salt slurry to a water inlet of the salt separation system 4 for circulating salt separation, and the mixed crystal salt is mixed crystal salt of sodium sulfate and sodium chloride;
the mixed salt drying system 11 is used for drying the mixed salt mother liquor and/or the sodium chloride evaporation crystallization mother liquor by using high-temperature steam to produce mixed salt;
the sodium sulfate centrifugal system 12 is used for centrifugally dewatering the sodium sulfate salt slurry to obtain sodium sulfate crystal salt;
the sodium sulfate drying and packaging system 13 is used for drying and packaging the sodium sulfate crystalline salt to obtain a finished product of the sodium sulfate crystalline salt;
the sodium bicarbonate calcining system 14 is used for calcining sodium bicarbonate to obtain sodium carbonate crystalline salt;
the sodium carbonate packaging system 15 is used for packaging the sodium carbonate crystalline salt to obtain a sodium carbonate crystalline salt industrial finished product;
the salt side sodium bicarbonate evaporative crystallization system 16 is used for separating sodium bicarbonate from nanofiltration water produced by nanofiltration and containing a large amount of sodium bicarbonate, sodium chloride and a trace amount of sodium sulfate through evaporative crystallization to obtain sodium bicarbonate salt slurry and a salt side evaporative crystallization mother liquor, wherein the salt side evaporative crystallization mother liquor contains sodium bicarbonate, sodium sulfate and sodium chloride which are not separated through crystallization;
the salt side freezing and crystallizing system 17 is used for cooling the salt side evaporation and crystallization mother liquor to further crystallize and separate out sodium bicarbonate in the salt side evaporation and crystallization mother liquor so as to obtain sodium bicarbonate salt slurry and the salt side freezing and crystallization mother liquor;
the sodium chloride evaporative crystallization system 18 is used for evaporating and crystallizing the salt side frozen crystallization mother liquor to separate out sodium chloride crystal salt, so as to obtain sodium chloride salt slurry and sodium chloride evaporative crystallization mother liquor;
the sodium chloride centrifugal system 19 is used for carrying out centrifugal dehydration on the sodium chloride salt slurry to obtain sodium chloride crystal salt;
the sodium chloride drying and packaging system 20 is used for packaging the sodium chloride crystal salt to obtain sodium chloride finished salt.
Example 5
As shown in fig. 6, a zero-emission treatment method and a treatment system for recycling negative hardness wastewater, wherein the treated negative hardness wastewater is mine water generated by coal mining, and the quality of the mine water is as follows:
K+＝10mg/L；Na+＝910mg/L；Ca2+＝69.2mg/L；Mg2+＝19.1mg/L；
SO42-＝903mg/L；HCO3 -＝760mg/L；pH＝8.4；SiO2＝19.5mg/L；TDS＝3206mg/L；
SS≤5mg/L；Cl-＝461mg/L；NO3 -＝30.4mg/L；
inflow rate of mine water 1250m3Firstly, the mine water is lifted to a mine water adjusting tank of the pretreatment system 1 through a water pump to play the roles of adjusting and buffering and accident water storage, and the effective volume of the adjusting tank is 15000m3And the retention time is 12 h. After the mine water is adjusted and buffered, the mine water is lifted to a V-shaped filter tank of the pretreatment system 1 through a water inlet pump, the normal filtration speed of the V-shaped filter tank is designed to be 8m/h, the turbidity of produced water is less than or equal to 10NTU, and backwashing water is collected and treated and then returns to the mine water adjusting tank at the front end of the system for circular treatment.
The water produced by the V-shaped filter chamber is lifted to a first-stage self-cleaning filter of the pretreatment system 1 by a water pump, the filtering precision of the self-cleaning filter is less than or equal to 100 mu m, a motor-driven suction type self-cleaning filter is selected, and a filter screen is made of SS316 materials.
The primary self-cleaning filter produced water is conveyed to the primary ultrafiltration of the pretreatment system 1, the primary ultrafiltration recovery rate is 92%, an external pressure type hollow fiber membrane is adopted, the ultrafiltration membrane is made of PVDF (polyvinylidene fluoride), the SDI (standard deviation index) index of the effluent is less than or equal to 3.0, the turbidity is less than or equal to 0.2NTU, and backwashing water is returned to a mine water regulating tank at the front end of the system for circulation treatment after being collected and treated.
Lifting the primary ultrafiltration product water to primary reverse osmosis of a pretreatment system 1 through a booster pump and a high-pressure pump, adjusting the pH of the primary reverse osmosis inlet water to 7.5-8.0, adopting a low-pressure anti-pollution roll type brackish water film for the primary reverse osmosis, wherein the recovery rate is 75%, collecting and recycling the product water, and the TDS of the product water is 49.8 mg/L; concentrated water flow 312.5m3Per, water quality of concentrated water K+＝39.6mg/L；Na+＝3604mg/L， SO42-＝3606mg/L，Cl-＝1820mg/L，Ca2+＝274.5mg/L，Mg2+＝74.8mg/L， HCO3 -＝2916mg/L，SiO2＝76.6mg/L，NO3 -116.8mg/L, TDS 12636 mg/L.
The first-stage reverse osmosis concentrated water is conveyed to a first-stage high-density sedimentation tank of the pretreatment system 1 through a water pump, the rising flow rate of the first-stage high-density sedimentation tank is 6m/h, and reinforced concrete is formedThe sodium metaaluminate is added into a first-level high-density sedimentation tank, and the adding amount is 153.2g/m3Adjusting pH to 8.0-8.5 with sodium hydroxide, adjusting pH to 7.0-7.5 with sulfuric acid, and adjusting water quality K+＝39.6mg/L，Na+＝3680mg/L，Cl-＝1820mg/L， SO4 2-＝3746mg/L，Ca2+＝247.5mg/L，Mg2+＝67.5mg/L，HCO3 -2715mg/L of SiO2＝13.5mg/L，NO3 -116.8mg/L, TDS 12750 mg/L.
The water produced by the first-level high-density sedimentation tank is lifted to a multi-media filter of the pretreatment system 1 through a water pump, the first-level multi-media filter is filled with quartz sand and anthracite, the quartz sand is 800mm high in layer, the anthracite is 400mm high in layer, suspended chemical sludge particles are intercepted, and backwashing water is collected and treated and then returns to the first-level high-density sedimentation tank for circular treatment.
The water produced by the primary multi-medium filter is lifted to a secondary self-cleaning filter of the pretreatment system 1 by a water pump, the filtering precision of the self-cleaning filter is less than or equal to 100 mu m, a motor-driven suction type self-cleaning filter is selected, and a filter screen is made of 316L stainless steel.
And (3) conveying the water produced by the secondary self-cleaning filter to secondary ultrafiltration of the pretreatment system 1, wherein the recovery rate of the secondary ultrafiltration is 92%, an external pressure type hollow fiber membrane is adopted, the ultrafiltration membrane is made of PVDF (polyvinylidene fluoride), the SDI (standard deviation index) index of the effluent is less than or equal to 3.0, the turbidity is less than or equal to 0.2NTU, and backwashing water is returned to the primary high-density sedimentation tank for circular treatment after being collected and treated.
The second-stage ultrafiltration produced water is conveyed to an ion exchange device of the softening system 2 by a water pump, the ion exchange device is filled with chelating resin in the form of weak acid type cation exchange resin, the running flow rate is 25m/h, the downstream acid-base regeneration mode is designed, the regeneration period is 24h, and the quality of the produced water Ca is2+≤1mg/L，Mg2+Less than or equal to 1mg/L, and the TDS is 12523 mg/L.
The produced water of the ion exchange device is lifted to the second-stage reverse osmosis of the membrane concentration system 3 by a booster pump and a high-pressure pump, the pH of the inlet water of the second-stage reverse osmosis is adjusted to 7.5-8.0, the second-stage reverse osmosis adopts an anti-pollution roll type seawater reverse osmosis membrane, the recovery rate is 80 percent, and the product water isCollecting and recycling, wherein the TDS of the product water is 196.8 mg/L; concentrated water flow 62.5m3Per, water quality of concentrated water K+＝192.6mg/L， Na+＝19850mg/L，Cl-＝8895mg/L，SO42-＝18587mg/L，Ca2+＝4.3mg/L， Mg2+＝4.3mg/L，HCO3 -＝12460mg/L，SiO2＝66.7mg/L，NO3 -547.6mg/L, TDS 61170 mg/L.
The second-stage reverse osmosis concentrated water is conveyed to a second-stage high-density sedimentation tank of the membrane concentration system 3 by a water pump, the rising flow rate of the second-stage high-density sedimentation tank is 3.6m/h, the reinforced concrete structure is adopted, sodium metaaluminate is added into the second-stage high-density sedimentation tank, and the adding amount is 73.8g/m3Adjusting pH to 8.0-8.5 with sodium hydroxide, adjusting pH to 7.0-7.5 with sulfuric acid to obtain product water K+＝192.6mg/L，Na+＝19948mg/L，Cl-＝8895mg/L， SO4 2-＝18707mg/L，Ca2+＝4.3mg/L，Mg2+＝4.3mg/L，HCO3 -Is 12460mg/L, SiO2＝10.2mg/L，NO3 -547.6mg/L, TDS 61272 mg/L.
The water produced by the second-stage high-density sedimentation tank is lifted to a second-stage multi-media filter of the membrane concentration system 3 through a water pump, the second-stage multi-media filter is filled with quartz sand and anthracite, the quartz sand is 800mm high in layer and the anthracite is 400mm high in layer, suspended chemical sludge particles are intercepted, and backwashing water is returned to the second-stage high-density sedimentation tank for circular treatment after being collected and treated.
The water produced by the second-stage multi-media filter is lifted to a third-stage self-cleaning filter of the membrane concentration system 3 by a water pump, the filtering precision of the self-cleaning filter is less than or equal to 100 mu m, a motor is used for driving the suction type self-cleaning filter, and a filter screen is made of 2205 dual-phase steel materials.
And (3) conveying the produced water of the third-level self-cleaning filter to a third-level ultrafiltration of the membrane concentration system 3, wherein the recovery rate of the third-level ultrafiltration is 92%, an external pressure type hollow fiber membrane is adopted, the ultrafiltration membrane is made of PVDF (polyvinylidene fluoride), the SDI (standard deviation index) index of the effluent is less than or equal to 3.0, the turbidity is less than or equal to 0.2NTU, and backwashing water is returned to the second-level high-density sedimentation tank for circular treatment after being collected and treated.
And the salt separating system 4 is connected with the three-stage ultrafiltration subsequently, the salt separating system 4 comprises a two-stage nanofiltration system, the water produced by the three-stage ultrafiltration firstly enters a first-stage nanofiltration device, the water produced by the first-stage nanofiltration device enters a second-stage nanofiltration device, and the concentrated water of the second-stage nanofiltration device flows back to the water inlet front end of the first-stage nanofiltration device to form an internal circulating system.
The three-stage ultrafiltration water is lifted to a first-stage nanofiltration device through a booster pump and a high-pressure pump, and the water inflow is 67m3H (4.5 m in the formula)3H is concentrated water of the secondary nanofiltration device), the pH of the inlet water of the primary nanofiltration device is adjusted to 7.5-8.0, a primary three-section combination mode is adopted, the membrane element adopts a GE brand nanofiltration membrane, the recovery rate is 67%, and the water production flow is 45m3H, conveying the mixture to a secondary nanofiltration device to obtain water K+＝191mg/L，Na+＝10557mg/L，Cl-＝8795mg/L，SO4 2-242.7mg/L, Ca2+0.03Mg/L, Mg2+0.03mg/L of HCO3 -Is 12340mg/L, SiO2＝10.3mg/L， NO3 -545.6mg/L, TDS 32981 mg/L; concentrated water flow 22m3H, conveying to a sodium bicarbonate evaporation crystallization system at the nitre side, and obtaining concentrated water quality K+＝196mg/L，Na+＝39156mg/L， Cl-＝9100mg/L，SO4 2-56475mg/L, Ca2+Is 13Mg/L, Mg2+13mg/L of HCO3 -12705mg/L of SiO2＝10mg/L，NO3 -552mg/L, TDS 118510 mg/L.
The water produced by the first stage nanofiltration is lifted to a second stage nanofiltration device by a booster pump and a high pressure pump, and the water inflow is 45m3H, adjusting the pH value of inlet water of the secondary nanofiltration device to 7.5-8.0, adopting a primary three-section combination mode, adopting a GE brand nanofiltration membrane as a membrane element, achieving a recovery rate of 90% and a water production flow of 40.5m3H, conveying to a high-pressure reverse osmosis device to produce water quality K+＝183mg/L，Na+＝10304mg/L， Cl-＝8695mg/L，SO4 2-Is 1mg/L, HCO3 -Is 12140mg/L, SiO2＝10.4mg/L， NO3 -544.6mg/L, TDS 31910 mg/L; concentrated water flow 4.5m3H, conveying the concentrated water to the front end of the water inlet of the primary nanofiltration device to form an internal circulating system, wherein the quality of the concentrated water K+＝263mg/L， Na+＝12834mg/L，Cl-＝9695mg/L，SO4 2-2418mg/L, Ca2+0.3Mg/L, Mg2+0.3mg/L, HCO3 -Is 14140mg/L, SiO2＝9.4mg/L，NO3 -554.6mg/L, TDS 40054 mg/L.
The water produced by the secondary nanofiltration device is lifted to the high-pressure reverse osmosis device by a booster pump and a high-pressure pump, and the water inflow is 40.5m3H, adjusting the pH value of inlet water of the high-pressure reverse osmosis device to 7.5-8.0, adopting a one-stage three-section combination mode, adopting a GE high-pressure reverse osmosis membrane element as a membrane element, achieving the recovery rate of 60 percent and the water production flow rate of 24.3m3Collecting and recycling product water, wherein the TDS of the product water is 641.6 mg/L; concentrated water flow 16.2m3H, conveying to a sodium bicarbonate evaporation crystallization system at the salt side, and obtaining concentrated water quality K+＝450.7mg/L，Na+＝25613mg/L，Cl-＝21468mg/L，SO4 2-2.49mg/L, HCO3 -Is 28988mg/L, SiO2＝25.5mg/L，NO3 -1311mg/L, TDS 78613 mg/L.
Concentrated water of the first-stage nanofiltration device is lifted to a sodium bicarbonate evaporative crystallization system 5 at the nitre side through a water pump, and the sodium bicarbonate evaporative crystallization system 5 at the nitre side is composed of a vapor compressor, an axial-flow pump, an evaporator and a crystallizer. The evaporator adopts a falling film evaporator, the crystallizer adopts an Oslo type crystallizer, the evaporation temperature is controlled to be 100-110 ℃, moisture in the raw material liquid is continuously evaporated to be steam, the steam is condensed and uniformly collected for recycling, the raw material liquid is continuously concentrated, the raw material liquid is crystallized when reaching a saturated state, sodium bicarbonate crystal salt is continuously separated out, sodium bicarbonate slurry is sent to a sodium bicarbonate centrifugal system 7 for solid-liquid separation, and the centrifuge is in a bipolar piston pusher centrifuge. And (3) conveying the mother liquor of the sodium bicarbonate evaporative crystallization system 5 on the nitrate side to a freezing crystallization system 6 on the nitrate side, continuously separating sodium bicarbonate from sodium sulfate and sodium chloride in the mother liquor, controlling the temperature to be 30-50 ℃, and conveying the separated sodium bicarbonate slurry to a sodium bicarbonate centrifugal system for solid-liquid separation. Mother liquor of the nitre side freezing and crystallizing system 6 is conveyed to a sodium sulfate evaporating and crystallizing system 8, and the sodium sulfate evaporating and crystallizing system 8 is composed of a vapor compressor, an axial flow pump, an evaporator and a crystallizer. The evaporator adopts a falling film evaporator, the crystallizer adopts an Oslo type crystallizer, the evaporation temperature is controlled to be 100-110 ℃, moisture in the raw material liquid is continuously evaporated to be steam, the steam is condensed and uniformly collected for recycling, the raw material liquid is continuously concentrated, the raw material liquid is crystallized when reaching a saturated state, sodium sulfate crystal salt is continuously separated out, sodium sulfate slurry is sent into a sodium sulfate centrifugal system 12 for solid-liquid separation, and the centrifuge is in a bipolar piston pusher centrifuge. Conveying the sodium sulfate crystallized salt subjected to centrifugal dehydration to a sodium sulfate drying and packaging system 13 for drying the crystallized salt, packaging and packaging finished salt, wherein the yield is 1.76t/h, the first-class product of the physical and chemical index I of the industrial sodium sulfate salt is achieved, and the purity is more than or equal to 99.0%. The sodium sulfate drying and packaging system 13 consists of a dryer and a packaging machine. The dryer is in the form of a fluidized bed and the packaging machine is a ton bag packaging machine.
Mother liquor of the sodium sulfate evaporative crystallization system 8 is conveyed to a mixed salt evaporative crystallization system 9, and the mixed salt evaporative crystallization system 9 is composed of a vapor compressor, an axial flow pump, an evaporator and a crystallizer. The evaporator adopts a falling film evaporator, the crystallizer adopts an FC type crystallizer, the evaporation temperature is controlled to be 100-110 ℃, moisture in the raw material liquid is continuously evaporated to be steam, the steam is uniformly collected after condensation and then recycled, the raw material liquid is continuously concentrated, the raw material liquid is crystallized when reaching a saturated state, and sodium sulfate, sodium chloride and other mixed crystal salts are continuously separated out. The mixed crystal salt has two treatment modes, wherein the first mode is that the mixed crystal salt is conveyed to a crude salt redissolution system, and strong brine is conveyed to the front end of primary nanofiltration water inlet to carry out circulating salt separation; and the second is to convey the mother liquor along with the miscellaneous salt evaporation crystallization system to a miscellaneous salt drying system for drying treatment to produce miscellaneous salt.
The concentrated water of the high-pressure reverse osmosis device of the salt separating system 4 is conveyed to a salt side sodium bicarbonate evaporative crystallization system 16, and the salt side sodium bicarbonate evaporative crystallization system 16 consists of a vapor compressor, an axial flow pump, an evaporator and a crystallizer. The evaporator adopts a falling film evaporator, the crystallizer adopts an Oslo type crystallizer, the evaporation temperature is controlled to be 100-110 ℃, moisture in the raw material liquid is continuously evaporated to be steam, the steam is condensed and uniformly collected for recycling, the raw material liquid is continuously concentrated, the raw material liquid is crystallized when reaching a saturated state, sodium bicarbonate crystal salt is continuously separated out, sodium bicarbonate slurry is sent to a sodium bicarbonate centrifugal system 7 for solid-liquid separation, and the centrifuge is in a bipolar piston pusher centrifuge. And (3) conveying the mother liquor of the salt side sodium bicarbonate evaporative crystallization system 16 to a salt side freezing crystallization system 17, continuously separating sodium bicarbonate from sodium sulfate and sodium chloride in the mother liquor, controlling the temperature to be 30-50 ℃, and conveying the separated sodium bicarbonate slurry to a sodium bicarbonate centrifugal system 7 for solid-liquid separation. The mother liquor of the salt side freezing crystallization system 17 is conveyed to a sodium chloride evaporation crystallization system 18, and the sodium chloride evaporation crystallization system 18 is composed of a vapor compressor, an axial flow pump, an evaporator and a crystallizer. The evaporator adopts a falling film evaporator, the crystallizer adopts an FC type crystallizer, the evaporation temperature is controlled to be 100-110 ℃, moisture in the raw material liquid is continuously evaporated to be steam, the steam is condensed and uniformly collected for recycling, the raw material liquid is continuously concentrated, the raw material liquid is crystallized when reaching a saturated state, sodium chloride crystal salt is continuously separated out, sodium chloride salt slurry is sent into a sodium chloride centrifugal system 19 for solid-liquid separation, and the centrifugal machine is in a bipolar piston pusher centrifugal machine. The centrifugally dehydrated sodium chloride crystal salt is conveyed to a sodium chloride drying and packaging system 20 for drying the crystal salt, and finished salt is packaged with the yield of 555.9kg/h, so that the secondary quality of the sodium chloride industrial dry salt is achieved, and the purity is more than or equal to 97.5%. The sodium chloride drying and packaging system 20 consists of a dryer and a packaging machine. The dryer is in the form of a fluidized bed and the packaging machine is a ton bag packaging machine. And conveying the mother liquor of the sodium chloride evaporative crystallization system to a miscellaneous salt evaporative crystallization system for uniform treatment.
After the sodium bicarbonate salt slurry is centrifugally dewatered by a sodium bicarbonate centrifugal system 7, sodium bicarbonate crystal salt is conveyed to a sodium bicarbonate calcining system 14, the calcining temperature is controlled at 270 ℃, sodium bicarbonate is heated and decomposed to generate sodium carbonate, the sodium carbonate is collected and conveyed to a sodium carbonate packing system 15, finished salt is packed, the yield is 630.34kg/h, the quality of II-class qualified products of industrial sodium carbonate salt physical and chemical indexes is achieved, and the purity is more than or equal to 98.0%. The sodium bicarbonate packaging machine is a ton bag packaging machine.
The sodium carbonate crystal salt part is used for treating calcium-containing regeneration waste liquid generated by a resin softening system, and the rest is sold.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.
Claims (10)
1. A zero-emission treatment method for recycling negative-hardness wastewater is characterized by comprising the following steps: the method comprises the following steps:
s1, softening and concentrating: purifying the negative-hardness wastewater, softening the negative-hardness wastewater by using ion exchange groups in resin, and concentrating and reducing to obtain a softened concentrated solution;
s2, nano-filtration salt separation: nanofiltration is carried out on the softened concentrated solution to separate salt so as to obtain nanofiltration concentrated water and nanofiltration produced water, the nanofiltration concentrated water is processed in a step S4, and the nanofiltration produced water is processed in a step S3;
s3, nano-filtration water production crystallization: evaporating and crystallizing nanofiltration water product to obtain sodium bicarbonate slurry and a salt side evaporation crystallization mother liquor, freezing and crystallizing the salt side evaporation crystallization mother liquor to obtain the sodium bicarbonate slurry and the salt side freezing crystallization mother liquor, evaporating and crystallizing the salt side freezing crystallization mother liquor to obtain sodium chloride slurry and a sodium chloride evaporation crystallization mother liquor, centrifugally drying the sodium chloride slurry and packaging to obtain a sodium chloride crystal salt finished product, producing mixed salt from the sodium chloride evaporation crystallization mother liquor through a drying system, and treating the sodium bicarbonate slurry in step S5;
s4, nano-filtration concentrated water crystallization: evaporating and crystallizing the nanofiltration concentrated water to obtain sodium bicarbonate slurry and nitrate side evaporation crystallization mother liquor, freezing and crystallizing the nitrate side evaporation crystallization mother liquor to obtain the sodium bicarbonate slurry and nitrate side freezing crystallization mother liquor, evaporating and crystallizing the nitrate side freezing crystallization mother liquor to obtain sodium sulfate slurry and nitrate side sodium sulfate evaporation crystallization mother liquor, centrifuging, drying and packaging the sodium sulfate slurry to obtain a sodium sulfate crystalline salt finished product, evaporating and crystallizing the nitrate side sodium sulfate evaporation mother liquor to obtain mixed salt slurry and mixed salt mother liquor, dissolving the mixed salt slurry back, drying the mixed salt mother liquor to obtain mixed salt, and treating the sodium bicarbonate slurry in step S5;
s5, centrifugal calcination and packaging: and the sodium bicarbonate salt slurry is centrifugally dewatered, calcined at high temperature and decomposed into sodium carbonate crystalline salt, and then packaged to obtain a finished product of the sodium carbonate crystalline salt, and the resource zero-discharge treatment of the negative-hardness wastewater is completed.
2. The resource zero-emission treatment method of negative-hardness wastewater according to claim 1, characterized in that: step S1 includes:
s11, preprocessing: lifting the negative-hardness wastewater to a pretreatment system (1) through a lifting pump to adjust the water quality and water quantity, removing pollution factors such as iron, fluoride and silicon dioxide by a medicament precipitation method, and removing colloid particles, suspended matters and partial organic matters in the wastewater through physical sedimentation and physical interception to obtain pretreated wastewater;
s12, softening: the pretreated wastewater enters a softening system (2), and ion exchange groups filled with resin in the softening system (2) are exchanged with calcium and magnesium ions, so that the effects of removing the calcium and magnesium ions in the wastewater and softening the wastewater are achieved, and softened water and resin regeneration waste liquid are obtained;
s13, concentration and decrement: and the softened produced water enters a membrane concentration system (3) for concentration and decrement to obtain the softened concentrated solution and membrane produced water, and the membrane produced water is collected and recycled.
3. The resource zero-emission treatment method of negative-hardness wastewater according to claim 1, characterized in that: the device for nanofiltration salt separation in the step S2 is a salt separation system (4), the salt separation system (4) is used for separating monovalent salt and divalent salt in the softened concentrated solution, the nanofiltration concentrated water contains sodium bicarbonate, sodium sulfate and sodium chloride, and the nanofiltration produced water contains sodium bicarbonate, sodium chloride and sodium sulfate.
4. The resource zero-emission treatment method of negative-hardness wastewater according to claim 1, characterized in that: step S3 includes:
s31, sodium bicarbonate on nitro side and evaporation crystallization: the nanofiltration concentrated water is lifted to a sodium bicarbonate evaporative crystallization system (5) at the nitrate side through a water pump, the sodium bicarbonate slurry and the sodium bicarbonate evaporative crystallization mother liquor at the nitrate side are obtained through evaporative crystallization, and the sodium bicarbonate slurry is conveyed to a sodium bicarbonate centrifugal system (7) and then enters a step S5 for treatment;
s32, freezing and crystallizing sodium bicarbonate on nitre side: the sodium nitrate side evaporation crystallization mother liquor is lifted to a sodium nitrate side freezing crystallization system (6) through a water pump to be subjected to freezing crystallization to obtain sodium bicarbonate slurry and the sodium nitrate side freezing crystallization mother liquor, and the sodium bicarbonate slurry is conveyed to the sodium bicarbonate centrifugal system (7) to enter a step S5 for treatment;
s33, evaporation and crystallization of sodium sulfate: lifting the sodium sulfate side frozen crystallization mother liquor to a sodium sulfate evaporation crystallization system (8) through a water pump, and carrying out evaporation crystallization to obtain sodium sulfate slurry and the sodium sulfate side frozen crystallization mother liquor, wherein the sodium sulfate slurry is conveyed to a sodium sulfate centrifugal system (12) for centrifugation and then conveyed to a sodium sulfate drying and packaging system (13) to obtain a sodium sulfate crystalline salt finished product;
s34, evaporating and crystallizing miscellaneous salts: the sodium sulfate evaporative crystallization mother liquor on the nitre side is lifted to a mixed salt evaporative crystallization system (9) through a water pump to be evaporated and crystallized to obtain mixed salt slurry and the mixed salt mother liquor, the mixed salt slurry is mixed salt slurry containing sodium sulfate and sodium chloride, the mixed salt slurry is conveyed to a crude salt redissolution system (10) to be redissolved and then conveyed to a water inlet of the salt separation system (4) to be subjected to circulating salt separation, and the mixed salt mother liquor is lifted to a mixed salt drying system (11) through the water pump to be dried to obtain the mixed salt.
5. The resource zero-emission treatment method of negative-hardness wastewater according to claim 4, characterized in that: in the step S31, the temperature of sodium bicarbonate evaporative crystallization is 100-110 ℃, and the condensate of the sodium bicarbonate evaporative crystallization is collected and recycled;
in the step S32, the temperature of sodium bicarbonate frozen crystallization is 30-50 ℃;
in the step S33, the temperature of sodium sulfate evaporative crystallization is 100-110 ℃, and condensate of the sodium sulfate evaporative crystallization is collected and recycled;
in step S34, the mixed salt slurry may also be conveyed to the mixed salt drying system (11) and dried to obtain the mixed salt.
6. The resource zero-emission treatment method of negative-hardness wastewater according to claim 1, characterized in that: step S4 includes:
s41, evaporative crystallization of sodium bicarbonate on salt side: the nanofiltration water is lifted to a sodium bicarbonate evaporative crystallization system (16) at a salt side through a water pump, the sodium bicarbonate salt slurry and the salt side evaporative crystallization mother liquor are obtained through evaporative crystallization, and the sodium bicarbonate crystallized salt slurry enters a sodium bicarbonate centrifugal system (7) and then is treated in a step S5;
s42, freezing and crystallizing sodium bicarbonate on the salt side: the salt side evaporation crystallization mother liquor is lifted to a salt side freezing crystallization system (17) through a water pump to obtain sodium bicarbonate slurry and the salt side freezing crystallization mother liquor through freezing crystallization, and the sodium bicarbonate slurry is conveyed to the sodium bicarbonate centrifugal system (7) and then enters step S5 for treatment;
s43, sodium chloride evaporation and crystallization: the salt side frozen crystallization mother liquor is lifted to a sodium chloride evaporative crystallization system (18) through a water pump to obtain sodium chloride salt slurry and sodium chloride evaporative crystallization mother liquor through evaporative crystallization, the sodium chloride salt slurry is conveyed to a sodium chloride centrifugal system (19) for centrifugation and then conveyed to a sodium chloride drying and packaging system (20) to obtain sodium chloride crystal salt, and the sodium chloride evaporative crystallization mother liquor is conveyed to a mixed salt drying system (11) for drying to produce mixed salt.
7. The resource zero-emission treatment method of negative-hardness wastewater according to claim 1, characterized in that: step S5 includes:
s51, sodium bicarbonate crystallization and centrifugal dehydration: conveying the sodium bicarbonate crystals to a sodium bicarbonate centrifugal system (7) for centrifugal dehydration to obtain sodium bicarbonate;
s52, sodium bicarbonate calcination: the sodium bicarbonate salt is conveyed to a sodium bicarbonate calcining system (14) to be heated and decomposed to generate sodium carbonate crystalline salt;
s53, packaging sodium carbonate: and conveying the sodium carbonate crystal salt to a sodium carbonate packaging system (15) for packaging to obtain a finished product of the sodium carbonate crystal salt.
8. The utility model provides a negative hardness waste water resourceful zero release processing system which characterized in that: comprises a pretreatment system (1), a softening system (2), a membrane concentration system (3), a salt separation system (4), a saltpeter side sodium bicarbonate evaporative crystallization system (5) connected with a concentrated water outlet of the salt separation system (4), a saltpeter side freezing crystallization system (6) connected with a mother liquor outlet of the saltpeter side sodium bicarbonate evaporative crystallization system (5), a sodium bicarbonate centrifugal system (7) connected with a salt slurry outlet of the saltpeter side sodium bicarbonate evaporative crystallization system (5), a sodium sulfate evaporative crystallization system (8) connected with a mother liquor outlet of the saltpeter side freezing crystallization system (6), a miscellaneous salt evaporative crystallization system (9) connected with a mother liquor outlet of the sodium sulfate evaporative crystallization system (8), a crude salt redissolution system (10) connected with a salt slurry outlet of the miscellaneous salt evaporative crystallization system (9), and a miscellaneous salt drying system (11) connected with a mother liquor outlet of the miscellaneous salt evaporative crystallization system (9), a sodium sulfate centrifugal system (12) connected with a salt slurry outlet of the sodium sulfate evaporative crystallization system (8), a sodium sulfate drying and packaging system (13) connected with an outlet of the sodium sulfate centrifugal system (12), a sodium bicarbonate calcining system (14) connected with an outlet of the sodium bicarbonate centrifugal system (7), a sodium carbonate packaging system (15) connected with an outlet of the sodium bicarbonate calcining system (14), a salt side sodium bicarbonate evaporative crystallization system (16) connected with a water production outlet of the salt separation system (4), a salt side freezing crystallization system (17) connected with a mother liquor outlet of the salt side sodium bicarbonate evaporative crystallization system (16), a sodium chloride evaporative crystallization system (18) connected with a mother liquor outlet of the salt side freezing crystallization system (17), and a sodium chloride centrifugal system (19) connected with a salt slurry outlet of the sodium chloride evaporative crystallization system (18), a sodium chloride drying and packing system (20) connected with the outlet of the sodium chloride centrifugal system (19);
the salt slurry outlet of the sodium bicarbonate evaporative crystallization system (5) on the nitrate side, the salt slurry outlet of the freezing crystallization system (6) on the nitrate side, the salt slurry outlet of the sodium bicarbonate evaporative crystallization system (16) on the salt side and the salt slurry outlet of the freezing crystallization system (17) on the salt side are all connected with the inlet of the sodium bicarbonate centrifugal system (7);
the pretreatment system (1) is used for adjusting the quality and quantity of the negative-hardness wastewater, removing iron, fluoride and silicon dioxide by a medicament precipitation method, and removing colloidal particles, suspended matters and partial organic matters in the wastewater by physical sedimentation and physical interception to obtain pretreated wastewater;
the softening system (2) is used for enabling ion exchange groups filled with resin to exchange with calcium ions and magnesium ions in the pretreated wastewater, so that the effects of removing the calcium ions and the magnesium ions in the wastewater and softening the wastewater are achieved, and meanwhile, bicarbonate is reserved, and softened water and resin regeneration waste liquid are obtained;
the membrane concentration system (3) is used for concentrating and reducing the softened produced water so as to enrich the salt, so as to obtain a softened concentrated solution and membrane produced water, and the membrane produced water is collected and recycled;
the salt separating system (4) is used for separating monovalent salt and divalent salt in the softened concentrated solution to obtain nanofiltration concentrated water and nanofiltration produced water;
the sodium bicarbonate evaporative crystallization system (5) on the nitrate side is used for separating sodium bicarbonate crystal salt from the nanofiltration concentrated water through evaporative crystallization to obtain mother liquor of sodium bicarbonate evaporative crystallization and sodium bicarbonate slurry;
the nitre side freezing and crystallizing system (6) is used for cooling the nitre side evaporation and crystallization mother liquor to further crystallize and separate out sodium bicarbonate in the nitre side evaporation and crystallization mother liquor so as to obtain nitre side freezing and crystallization mother liquor and sodium bicarbonate slurry;
the sodium bicarbonate centrifugal system (7) is used for centrifugally dewatering the sodium bicarbonate salt slurry to obtain sodium bicarbonate salt;
the sodium sulfate evaporative crystallization system (8) is used for separating sodium sulfate crystal salt from the sodium nitrate side freezing crystallization mother liquor through evaporative crystallization to obtain sodium sulfate slurry and sodium sulfate evaporative crystallization mother liquor on the sodium nitrate side;
the mixed salt evaporative crystallization system (9) is used for separating out sodium sulfate and sodium chloride mixed crystallization salt by carrying out evaporative crystallization on the sodium sulfate evaporative crystallization mother liquor on the nitre side to obtain mixed salt slurry and mixed salt mother liquor;
the crude salt redissolution system (10) comprises a redissolution water tank and a lift water pump which are connected, the crude salt redissolution system (10) is used for redissolving the mixed salt slurry containing the mixed crystal salt and then conveying the mixed salt slurry to a water inlet of the salt separation system (4) for circulating salt separation, and the mixed crystal salt is mixed crystal salt of sodium sulfate and sodium chloride;
the mixed salt drying system (11) is used for drying the mixed salt mother liquor and/or the sodium chloride evaporation crystallization mother liquor by using high-temperature steam to produce mixed salt;
the sodium sulfate centrifugal system (12) is used for centrifugally dewatering the sodium sulfate salt slurry to obtain sodium sulfate crystalline salt;
the sodium sulfate drying and packaging system (13) is used for drying and packaging the sodium sulfate crystalline salt to obtain a finished product of the sodium sulfate crystalline salt;
the sodium bicarbonate calcining system (14) is used for calcining the sodium bicarbonate salt to obtain sodium carbonate crystalline salt;
the sodium carbonate packaging system (15) is used for packaging the sodium carbonate crystalline salt to obtain a sodium carbonate crystalline salt industrial finished product;
the salt side sodium bicarbonate evaporative crystallization system (16) is used for separating sodium bicarbonate from nanofiltration water produced by sodium bicarbonate, sodium chloride and sodium sulfate through evaporative crystallization to obtain sodium bicarbonate salt slurry and salt side evaporative crystallization mother liquor, wherein the salt side evaporative crystallization mother liquor comprises sodium bicarbonate, sodium sulfate and sodium chloride which are not separated through crystallization;
the salt side freezing and crystallizing system (17) is used for cooling the salt side evaporation and crystallization mother liquor to further crystallize and separate out sodium bicarbonate in the salt side evaporation and crystallization mother liquor so as to obtain sodium bicarbonate salt slurry and the salt side freezing and crystallization mother liquor;
the sodium chloride evaporative crystallization system (18) is used for carrying out evaporative crystallization on the salt side frozen crystallization mother liquor to separate out sodium chloride crystal salt, so as to obtain sodium chloride salt slurry and sodium chloride evaporative crystallization mother liquor;
the sodium chloride centrifugal system (19) is used for carrying out centrifugal dehydration on the sodium chloride salt slurry to obtain sodium chloride crystal salt;
the sodium chloride drying and packaging system (20) is used for packaging the sodium chloride crystal salt to obtain sodium chloride finished salt.
9. The recycling zero-emission treatment system for negative-hardness wastewater according to claim 8, characterized in that: the water outlet of the mixed salt redissolution system (9) is connected with the water inlet of the salt separating system (4).
10. The recycling zero-emission treatment system for negative-hardness wastewater according to claim 8, characterized in that: the pretreatment system (1) is any one or more of the following systems: the device comprises a regulating tank, a high-density sedimentation tank, a V-shaped filter tank, a valveless filter tank, a manganese sand filter and a multi-media filter;
the softening system (2) is an ion exchange device, and weak acid type cation exchange resin is filled in the softening system (2);
the membrane concentration system (3) is any one or more of the following systems: self-cleaning filter, ultrafiltration device, reverse osmosis unit, high pressure reverse osmosis unit and electrodialysis device.
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