High-salinity wastewater treatment system
By designing a high-salt wastewater treatment system containing membrane concentration separation, low-temperature oxidation and crystallization units, the problem of insufficient organic matter treatment in the existing system is solved, and efficient organic matter removal and salt product quality improvement is achieved.
Patent Information
- Application Number
- CN202421563849.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-03
- Publication Date
- 2025-06-17
- Estimated Expiration
- 2034-07-03
AI Technical Summary
The existing high-salt wastewater treatment system has problems such as membrane congestion, evaporation system scale and poor salt product quality when treating organic matter. The existing treatment processes such as catalytic oxidation and Fenton oxidation have high operating costs and secondary pollution risks.
A high-salt wastewater treatment system was designed, including a membrane concentration separation device, a low-temperature oxidation device, a sodium sulfate and sodium chloride crystal unit. The macromolecular organic matter was separated and intercepted through membrane concentration, and the small-molecular organic matter was treated in depth at low temperature oxidation, and the salt products were recovered through the crystallization unit to ensure product quality.
The effective treatment of organic matter in high-salt wastewater is achieved, the risks of membrane pollution blockage and evaporation system scale are reduced, the quality of salt products is improved, and the operating costs and secondary pollution are reduced.
Smart Images
Figure CN222989942U_ABST
Abstract
Description
Technical Field:
[0001] The utility model relates to the technical field of wastewater treatment, and particularly relates to a high-salt wastewater treatment system. Background Art:
[0002] At present, there are still a large amount of organic matters in high-salt wastewater. When treated by the existing treatment system, that is, through pretreatment → membrane concentration → purification (impurity treatment) → evaporation crystallization in sequence, there is a problem that the organic impurities are not treated sufficiently. If the organic matters in high-salt wastewater are not effectively treated, it will cause membrane fouling, scaling in the subsequent evaporation system, and affect the quality of by-product salt (that is, the TOC content in the salt product is high, resulting in the yellowing of the salt product).
[0003] The existing organic matter treatment processes include catalytic oxidation, Fenton oxidation, etc. The catalytic oxidation has a low removal efficiency of organic matters, and equipment failures are likely to occur, and the operation effect is unstable. Fenton oxidation: sludge and a part of polluting gases will be generated after the reaction, causing secondary pollution. The equipment occupies a large area. The above two methods have the phenomena of high operation costs, high investment, and incomplete removal. Content of the Utility Model:
[0004] The purpose of the utility model is to provide a high-salt wastewater treatment system with a simple connection structure, energy saving, and ensuring the quality of the final salt product.
[0005] The utility model is implemented by the following technical solutions: The purpose of this patent is to provide a high-salt wastewater treatment system, including a high-salt wastewater pipeline, a pretreatment system, a membrane concentration and separation device, a resin soft water equipment, a nanofiltration device, a low-temperature oxidation device, a sodium sulfate crystallization unit, a reverse osmosis device, and a sodium chloride crystallization unit; the high-salt wastewater pipeline, the pretreatment system, the membrane concentration and separation device, the resin soft water equipment and the nanofiltration device are connected in sequence, the concentrated water outlet of the nanofiltration device is connected to the water inlet of the low-temperature oxidation device, the water outlet of the low-temperature oxidation device is connected to the water inlet of the sodium sulfate raw water tank of the sodium sulfate crystallization unit, the water production outlet of the nanofiltration device is connected to the water inlet of the reverse osmosis device, and the water outlet of the reverse osmosis device is connected to the water inlet of the sodium chloride raw water tank of the sodium chloride crystallization unit; the mother liquor outlets of the sodium sulfate crystallization unit and the sodium chloride crystallization unit are both connected to the liquid inlet of the mixed salt treatment unit.
[0006] Further, the pretreatment system includes an adjustment tank, a high-density tank, a sand filtration device, and an ultrafiltration device that are connected in sequence according to the wastewater flow direction.
[0007] Further, the sodium sulfate crystallization unit includes a sodium sulfate raw water tank, a mirabilite evaporation device, a primary pre-cooler, a secondary pre-cooler, a freezing crystallization device, a mirabilite settler, a mirabilite centrifuge, a mirabilite dissolution tank, a sodium sulfate evaporation device, a sodium sulfate thickener, a sodium sulfate centrifuge, and a sodium sulfate fluidized drying bed that are connected in sequence according to the material flow direction; a circulating hot water pipeline is connected to the water inlet of the jacket of the mirabilite dissolution tank, and the water outlet of the jacket of the mirabilite dissolution tank is connected to the cold medium inlet of the primary pre-cooler; the overflow port of the mirabilite settler is connected to the liquid inlet of the mirabilite clear liquid tank, the liquid outlet of the mirabilite clear liquid tank is connected to the cold medium inlet of the secondary pre-cooler, and the cold medium outlet of the secondary pre-cooler is connected to the mixed salt feed tank of the mixed salt treatment unit; the overflow port of the sodium sulfate thickener and the mother liquor outlet of the sodium sulfate centrifuge are both connected to the liquid inlet of the mirabilite dissolution tank.
[0008] Further, it further includes a steam pipeline, a primary pre-heater, and a secondary pre-heater. The steam pipeline is respectively connected to the air inlets of the mirabilite evaporation device and the sodium sulfate evaporation device. The condensate outlet of the mirabilite evaporation device is connected to the hot medium inlet of the primary pre-heater, and the condensate outlet of the sodium sulfate evaporation device is connected to the hot medium inlet of the secondary pre-heater; according to the material flow direction, the sodium sulfate raw water tank, the primary pre-heater, the secondary pre-heater, and the mirabilite evaporation device are connected in sequence.
[0009] Further, the freezing crystallization device includes a mirabilite crystallizer and a mirabilite cooler; the material outlet of the secondary pre-cooler is connected to the feed inlet of the mirabilite cooler, the discharge outlet of the mirabilite cooler is connected to the feed inlet of the mirabilite crystallizer, and the discharge outlet of the mirabilite crystallizer is respectively connected to the feed inlet of the mirabilite cooler and the feed inlet of the mirabilite settler; the mother liquor outlet of the mirabilite centrifuge is connected to the feed inlet of the mirabilite crystallizer.
[0010] Further, the sodium chloride crystallization unit includes a sodium chloride raw water tank, a triple-effect evaporation device, a sodium chloride thickener, a sodium chloride centrifuge, and a sodium chloride fluidized drying bed that are connected in sequence according to the material flow direction. The mother liquor outlet of the sodium chloride centrifuge is connected to the mixed salt feed tank of the mixed salt treatment unit.
[0011] Further, the mixed salt treatment unit includes a mixed salt feed tank, a mixed salt evaporation device, a mixed salt thickener, a mixed salt centrifuge, a mixed salt dissolution tank, and a drum dryer; the mixed salt feed tank, the mixed salt evaporation device, the mixed salt thickener, and the mixed salt centrifuge are connected in sequence according to the flow direction of the mixed salt material, the mixed salt outlet of the mixed salt centrifuge is connected to the feed port of the mixed salt dissolution tank, the condensate outlet of the mixed salt evaporation device is connected to the water inlet of the mixed salt dissolution tank, the liquid outlet of the mixed salt dissolution tank is connected to the water inlet of the adjustment tank; the liquid outlet of the mixed salt centrifuge is connected to the liquid inlet of the drum dryer.
[0012] Advantages of the present invention: 1. The connection structure of the present invention is simple and easy to implement. By setting a membrane concentration separation device to effectively intercept macromolecular organic matter, the subsequent system is ensured to be stable, and the TOC removal rate is 40-60%; after salt separation by the nanofiltration equipment, the organic matter in the concentrated water is further enriched, but mainly consists of small molecular and easily oxidizable organic matter. Therefore, further deep treatment is realized through the low-temperature oxidation device, without generating sludge or harmful secondary pollution gases, reducing the amount of miscellaneous salts generated, saving the hazardous waste treatment cost; and the quality of the final salt product is ensured.
[0013] 2. By setting a primary pre-cooler, a secondary pre-cooler, a primary pre-heater, and a secondary pre-heater in the sodium sulfate crystallization unit, the recovery of cold and heat energy is realized, saving energy; and by sending the mother liquor centrifuged out by the mirabilite centrifuge back to the mirabilite crystallizer for brine mixing to provide mirabilite crystal seeds, the crystallization and scaling rate of the heat exchange tubes of the mirabilite cooler is effectively delayed. Description of the drawings:
[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0015] Figure 1 It is a schematic diagram of the overall structure of the present invention.
[0016] Figure 2 It is a schematic diagram of the structure of the sodium sulfate crystallization unit.
[0017] Figure 3 It is a schematic diagram of the structure of the sodium chloride crystallization unit.
[0018] Figure 4 It is a schematic diagram of the structure of the mixed salt treatment unit.
[0019] High-salt wastewater pipeline 1, pretreatment system 2, regulating tank 21, high-density tank 22, sand filtration device 23, ultrafiltration device 24, membrane concentration and separation device 3, resin soft water equipment 4, nanofiltration equipment 5, low-temperature oxidation device 6, sodium sulfate crystallization unit 7, sodium sulfate raw water tank 701, mirabilite evaporation device 702, primary pre-cooler 703, secondary pre-cooler 704, freezing crystallization device 705, mirabilite crystallizer 7051, mirabilite cooler 7052, mirabilite settler 706, mirabilite centrifuge 707, mirabilite dissolution tank 708, sodium sulfate evaporation device 709, sodium sulfate thickener 710, sodium sulfate centrifuge 711, sodium sulfate fluidized drying bed 712, steam pipeline 713, primary pre-heater 714, secondary pre-heater 715, mirabilite clear liquid tank 716, circulating hot water pipeline 717, reverse osmosis device 8, sodium chloride crystallization unit 9, sodium chloride raw water tank 91, triple-effect evaporation device 92, sodium chloride thickener 93, sodium chloride centrifuge 94, sodium chloride fluidized drying bed 95, mixed salt treatment unit 10, mixed salt feed tank 101, mixed salt evaporation device 102, mixed salt thickener 103, mixed salt centrifuge 104, mixed salt dissolution tank 105, drum dryer 106. Specific implementation manner:
[0020] Example: As Figure 1 shown, a high-salt wastewater treatment system includes a high-salt wastewater pipeline 1, a pretreatment system 2, a membrane concentration and separation device 3, a resin soft water equipment 4, a nanofiltration equipment 5, a low-temperature oxidation device 6, a sodium sulfate crystallization unit 7, a reverse osmosis device 8 and a sodium chloride crystallization unit 9; the high-salt wastewater pipeline 1, the pretreatment system 2, the membrane concentration and separation device 3, the resin soft water equipment 4 are connected in sequence with the nanofiltration equipment 5, the concentrated water outlet of the nanofiltration equipment 5 is connected with the water inlet of the low-temperature oxidation device 6, the water outlet of the low-temperature oxidation device 6 is connected with the water inlet of the sodium sulfate raw water tank 701 of the sodium sulfate crystallization unit 7, the produced water outlet of the nanofiltration equipment 5 is connected with the water inlet of the reverse osmosis device 8, the water outlet of the reverse osmosis device 8 is connected with the water inlet of the sodium chloride raw water tank 91 of the sodium chloride crystallization unit 9; the mother liquor outlets of the sodium sulfate crystallization unit 7 and the sodium chloride crystallization unit 9 are both connected with the liquid inlet of the mixed salt treatment unit 10.
[0021] The pretreatment system 2 includes a regulating tank 21, a high-density tank 22, a sand filtration device 23 and an ultrafiltration device 24 that are connected in sequence according to the wastewater flow direction.
[0022] As Figure 2As shown in the figure, the sodium sulfate crystallization unit 7 includes a sodium sulfate raw water tank 701, a mirabilite evaporation device 702, a primary pre-cooler 703, a secondary pre-cooler 704, a freezing crystallization device 705, a mirabilite settler 706, a mirabilite centrifuge 707, a mirabilite dissolving tank 708, a sodium sulfate evaporation device 709, a sodium sulfate thickener 710, a sodium sulfate centrifuge 711, and a sodium sulfate fluidized drying bed 712, which are connected in sequence according to the material flow direction; a circulating hot water pipeline 717 is connected to the water inlet of the jacket of the mirabilite dissolving tank 708, and the water outlet of the jacket of the mirabilite dissolving tank 708 is connected to the cold medium inlet of the primary pre-cooler 703; the overflow port of the mirabilite settler 706 is connected to the liquid inlet of the mirabilite clear liquid tank 716, the liquid outlet of the mirabilite clear liquid tank 716 is connected to the cold medium inlet of the secondary pre-cooler 704, and the cold medium outlet of the secondary pre-cooler 704 is connected to the mixed salt feed tank 101 of the mixed salt treatment unit 10; the overflow port of the sodium sulfate thickener 710 and the mother liquor outlet of the sodium sulfate centrifuge 711 are both connected to the liquid inlet of the mirabilite dissolving tank 708.
[0023] It further includes a steam pipeline 713, a primary pre-heater 714, and a secondary pre-heater 715. The steam pipeline 713 is respectively connected to the steam inlets of the mirabilite evaporation device 702 and the sodium sulfate evaporation device 709. The condensate outlet of the mirabilite evaporation device 702 is connected to the hot medium inlet of the primary pre-heater 714, and the condensate outlet of the sodium sulfate evaporation device 709 is connected to the hot medium inlet of the secondary pre-heater 715; according to the material flow direction, the sodium sulfate raw water tank 701, the primary pre-heater 714, the secondary pre-heater 715, and the mirabilite evaporation device 702 are connected in sequence.
[0024] The freezing crystallization device 705 includes a mirabilite crystallizer 7051 and a mirabilite cooler 7052; the material outlet of the secondary pre-cooler 704 is connected to the feed inlet of the mirabilite cooler 7052, the discharge outlet of the mirabilite cooler 7052 is connected to the feed inlet of the mirabilite crystallizer 7051, and the discharge outlet of the mirabilite crystallizer 7051 is respectively connected to the feed inlet of the mirabilite cooler 7052 and the feed inlet of the mirabilite settler 706; the mother liquor outlet of the mirabilite centrifuge 707 is connected to the feed inlet of the mirabilite crystallizer 7051.
[0025] As Figure 3 shown in the figure, the sodium chloride crystallization unit 9 includes a sodium chloride raw water tank 91, a triple-effect evaporation device 92, a sodium chloride thickener 93, a sodium chloride centrifuge 94, and a sodium chloride fluidized drying bed 95, which are connected in sequence according to the material flow direction. The mother liquor outlet of the sodium chloride centrifuge 94 is connected to the mixed salt feed tank 101 of the mixed salt treatment unit 10.
[0026] As Figure 4As shown in the figure, the mixed salt treatment unit 10 includes a mixed salt feed tank 101, a mixed salt evaporation device 102, a mixed salt thickener 103, a mixed salt centrifuge 104, a mixed salt dissolution tank 105, and a drum dryer 106; the mixed salt feed tank 101, the mixed salt evaporation device 102, the mixed salt thickener 103, and the mixed salt centrifuge 104 are connected in sequence according to the flow direction of the mixed salt material. The mixed salt outlet of the mixed salt centrifuge 104 is connected to the feed port of the mixed salt dissolution tank 105. The condensate outlet of the mixed salt evaporation device 102 is connected to the water inlet of the mixed salt dissolution tank 105. The liquid outlet of the mixed salt dissolution tank 105 is connected to the water inlet of the adjustment tank 21 of the sodium chloride crystallization unit 9; the liquid outlet of the mixed salt centrifuge 104 is connected to the liquid inlet of the drum dryer 106.
[0027] Working principle:
[0028] The high-salt wastewater enters the adjustment tank 21 for raw water quality adjustment. The adjustment time is 10 hours, and a submersible stirring system is equipped in the tank; then it enters the high-density tank 22, and sodium aluminate is added in the high-density tank 22. The silicon and heavy metal ions in the wastewater are removed by physical and chemical methods. Since sodium aluminate is added, the amount of sludge (solid waste) generated is relatively small, thus reducing the sludge disposal cost. The generated sludge is pumped to the sludge dewatering system for dewatering treatment.
[0029] The wastewater treated by the high-density tank 22 passes through the sand filtration device 23 and the ultrafiltration device 24 in sequence. The sand filtration device 23 further filters and removes the suspended solids in the incoming water to ensure the normal and stable operation of the subsequent ultrafiltration system; the ultrafiltration device 24 further removes impurities such as suspended solids, colloids, slime, microorganisms, and macromolecular organic matters that can cause membrane fouling, meeting the requirement that the SDI of the reverse osmosis feed water ≤ 3.
[0030] The pretreated wastewater is sent to the membrane concentration and separation device 3 to effectively intercept the macromolecular organic matters in the wastewater, ensuring the stability of the subsequent system, and the TOC removal rate is 40 - 60%. Ensure that the subsequent evaporation and crystallization unit can operate stably for a long time and ensure that the evaporated and crystallized salt can reach high quality.
[0031] The wastewater after membrane concentration and separation is sent to the resin softening water equipment 4 to replace the Ca 2+ , Mg 2+ in the wastewater with the groups in the exchanger, converting the scale-forming calcium and magnesium compounds into water-soluble sodium compounds that do not form scale, thus softening the wastewater.
[0032] The wastewater softened by resin is desalted by a nanofiltration device. The produced water is filtered by a reverse osmosis device 8, and the produced water is recycled. The concentrated water is sent to a sodium chloride crystallization unit 9 for crystallization to obtain sodium chloride salt. The concentrated water after desalting by the nanofiltration device is sent to a low-temperature oxidation device 6 for further oxidation treatment of the small-molecule easily oxidizable organic matter in the concentrated water, reducing the TOC of the wastewater and making the TOC in the final crystalline salt product meet the standard. Then it is sent to a sodium sulfate crystallization unit 7 for crystallization to obtain sodium sulfate salt.
[0033] The concentrated water after passing through the reverse osmosis device 8 enters the sodium chloride raw water tank 91 after pH adjustment. The sodium chloride feed liquid is conveyed into a triple-effect evaporation device 92 by a sodium chloride feed pump for concentration and crystallization. The concentrated crystallization liquid is sent into a sodium chloride thickener 93 by a sodium chloride discharge pump for thickening. The thickened crystal slurry flows into a sodium chloride centrifuge 94 by itself for centrifugal separation to obtain wet salt. The wet salt enters a sodium chloride fluidized drying bed 95 through a wet salt screw conveyor for drying. The dried product salt enters the sodium chloride product silo for temporary storage, and then enters a semi-automatic sodium chloride product ton bagging machine for bagging, and is then transported to the owner's salt product workshop for temporary storage by a forklift. The mother liquor centrifuged by the sodium chloride centrifuge 94 is sent into a mixed salt feed tank 101 of a mixed salt treatment unit 10.
[0034] The wastewater after being oxidized by the low-temperature oxidation device 6 enters the sodium sulfate raw water tank 701 after pH adjustment. The sodium sulfate feed liquid is transported by the sodium sulfate feed pump to the primary preheater 714 for heat exchange, and then enters the mirabilite evaporation device 702 for evaporation and concentration after heat exchange through the secondary preheater 715. The concentrated liquid is transported to the primary precooler 703 for heat exchange and precooling by the sodium sulfate concentrated discharge pump, and then enters the mirabilite cooler 7052 for cooling after heat exchange through the secondary precooler 704. Then it enters the mirabilite crystallizer 7051 for crystallization. The solution circulates between the mirabilite crystallizer 7051 and the mirabilite cooler 7052 for cooling and crystallization. The mirabilite crystallization liquid is pushed by the sodium sulfate concentrated discharge pump into the mirabilite thickener 706 for thickening. The thickened crystal slurry flows into the mirabilite centrifuge 707 by gravity for centrifugal separation of mirabilite, and the mirabilite falls vertically into the mirabilite dissolution tank 708. The overflow liquid of the mirabilite thickener 706 enters the mirabilite clear liquid tank 716, and the mirabilite clear liquid is transported out by the mirabilite clear liquid pump. First, it enters the secondary precooler 704 to freeze the sodium sulfate concentrated liquid, and then enters the mixed salt feed tank 101 after heat exchange. The centrifugal mother liquor of the mirabilite centrifuge 707 enters the mirabilite mother liquor tank, and the mirabilite mother liquor is pumped back to the mirabilite crystallizer 7051 for brine blending to provide mirabilite crystal seeds and delay the crystallization and scaling rate of the heat exchange tubes of the mirabilite cooler 7052. Heat circulating water is passed through the jacket of the mirabilite dissolution tank 708 to heat up and dissolve the mirabilite. The cooled circulating water enters the primary precooler 703 to cool the sodium sulfate concentrated liquid, and the nitrate solution is pumped into the sodium sulfate evaporation device 709 by the nitrate pump for concentration and crystallization. The crystal slurry liquid is sent to the sodium sulfate thickener 710 by the sodium sulfate discharge pump for thickening. The thickened crystal slurry flows into the sodium sulfate centrifuge 711 by gravity for centrifugal separation of wet nitrate. The wet nitrate enters the sodium sulfate fluidized drying bed 712 through the wet nitrate screw conveyor for drying. The dried sodium sulfate product enters the sodium sulfate product bin for temporary storage, and then enters the semi-automatic ton bagging machine for the sodium sulfate product for bagging, and is then transported to the owner's salt product workshop for temporary storage by forklift. The overflow liquid of the sodium sulfate thickener 710 and the centrifugal mother liquor of the sodium sulfate centrifuge 711 flow into the mirabilite dissolution tank 708 for dissolving mirabilite.
[0035] The feed liquid in the mixed salt feed tank 101 is pumped into the mixed salt evaporation device 102 by the mixed salt feed pump. The feed liquid is concentrated and crystallized in the mixed salt evaporation device 102. The crystal slurry liquid is sent to the mixed salt thickener 103 by the mixed salt discharge pump for thickening. The thickened crystal slurry flows into the mixed salt centrifuge 104 by gravity for centrifugal separation of the mixed salt. The mixed salt falls vertically into the mixed salt dissolution tank 105, and additional mixed salt condensate is added to dissolve the mixed salt. The mixed salt solution is transported to the adjustment tank 21 by the mixed salt dissolution pump to achieve the effective recovery of sodium sulfate and sodium chloride. The mother liquor separated by the mixed salt centrifuge 104 enters the drum dryer 106 for drying, and the dried miscellaneous salt falls vertically into the miscellaneous salt packaging bag.
[0036] The above are only the preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.
Claims
1. A high-salinity wastewater treatment system, characterized in that: It includes a high-salt wastewater pipeline, a pretreatment system, a membrane concentration and separation device, a resin softening water device, a nanofiltration device, a low-temperature oxidation device, a sodium sulfate crystallization unit, a reverse osmosis device and a sodium chloride crystallization unit; the high-salt wastewater pipeline, the pretreatment system, the membrane concentration and separation device, the resin softening water device and the nanofiltration device are connected in sequence, the concentrated water outlet of the nanofiltration device is connected to the water inlet of the low-temperature oxidation device, the water outlet of the low-temperature oxidation device is connected to the water inlet of the sodium sulfate raw water pool of the sodium sulfate crystallization unit, the water production outlet of the nanofiltration device is connected to the water inlet of the reverse osmosis device, and the water outlet of the reverse osmosis device is connected to the water inlet of the sodium chloride raw water pool of the sodium chloride crystallization unit; the mother liquor outlets of the sodium sulfate crystallization unit and the sodium chloride crystallization unit are both connected to the liquid inlet of the mixed salt treatment unit.
2. A high-salinity wastewater treatment system according to claim 1, characterized in that: The pretreatment system comprises a regulating tank, a high-density tank, a sand filtration device and an ultrafiltration device which are sequentially connected according to the flow of the wastewater.
3. A high-salt wastewater treatment system according to claim 1 or 2, characterized in that: The sodium sulfate crystallization unit comprises a sodium sulfate raw water pool, a sodium sulfate evaporation device, a primary precooler, a secondary precooler, a freezing crystallization device, a sodium sulfate settler, a sodium sulfate centrifuge, a sodium sulfate dissolving tank, a sodium sulfate evaporation device, a sodium sulfate thickener, a sodium sulfate centrifuge and a sodium sulfate fluidized drying bed, which are connected in sequence according to the direction of the materials; a circulating hot water pipeline is connected to the water inlet of the jacket of the sodium sulfate dissolving tank, and the water outlet of the jacket of the sodium sulfate dissolving tank is connected to the cold medium inlet of the primary precooler; the overflow of the sodium sulfate settler is connected to the liquid inlet of the sodium sulfate clear liquid tank, the liquid outlet of the sodium sulfate clear liquid tank is connected to the cold medium inlet of the secondary precooler, and the cold medium outlet of the secondary precooler is connected to the mixed salt feed tank of the mixed salt treatment unit; the overflow of the sodium sulfate thickener and the mother liquor outlet of the sodium sulfate centrifuge are both connected to the liquid inlet of the sodium sulfate dissolving tank.
4. A high-salinity wastewater treatment system according to claim 3, characterized in that: It also includes a steam pipeline, a primary preheater and a secondary preheater. The steam pipeline is connected to the air inlets of the mirabilite evaporation device and the sodium sulfate evaporation device respectively. The condensate outlet of the mirabilite evaporation device is connected to the heat medium inlet of the primary preheater, and the condensate outlet of the sodium sulfate evaporation device is connected to the heat medium inlet of the secondary preheater. According to the direction of the materials, the sodium sulfate raw water pool, the primary preheater, the secondary preheater and the mirabilite evaporation device are connected in sequence.
5. A high-salinity wastewater treatment system according to claim 4, characterized in that: The freezing crystallization device includes a Glauber's salt crystallizer and a Glauber's salt cooler; the material outlet of the secondary precooler is connected to the feed port of the Glauber's salt cooler, the discharge port of the Glauber's salt cooler is connected to the feed port of the Glauber's salt crystallizer, and the discharge port of the Glauber's salt crystallizer is respectively connected to the feed port of the Glauber's salt cooler and the feed port of the Glauber's salt settler; the mother liquor outlet of the Glauber's salt centrifuge is connected to the feed port of the Glauber's salt crystallizer.
6. A high-salinity wastewater treatment system according to claim 1 or 2, characterized in that: The sodium chloride crystallization unit comprises a sodium chloride raw water pool, a three-effect evaporator, a sodium chloride thickener, a sodium chloride centrifuge and a sodium chloride fluidized drying bed which are sequentially connected according to the material flow, and the mother liquor outlet of the sodium chloride centrifuge is connected to the mixed salt feed tank of the mixed salt processing unit.
7. A high-salinity wastewater treatment system according to claim 2, characterized in that: The mixed salt processing unit includes a mixed salt feeding tank, a mixed salt evaporating device, a mixed salt thickener, a mixed salt centrifuge, a mixed salt dissolving tank and a drum dryer; the mixed salt feeding tank, the mixed salt evaporating device, the mixed salt thickener and the mixed salt centrifuge are connected in sequence according to the direction of the mixed salt material, the mixed salt outlet of the mixed salt centrifuge is connected to the feed port of the mixed salt dissolving tank, the condensed water outlet of the mixed salt evaporating device is connected to the water inlet of the mixed salt dissolving tank, and the liquid outlet of the mixed salt dissolving tank is connected to the water inlet of the regulating tank; the liquid outlet of the mixed salt centrifuge is connected to the liquid inlet of the drum dryer.