MVR evaporation system and method for synergistically treating preserved vegetable wastewater

Abstract

The present application relates to a kind of MVR evaporation system and method for synergic resourceful processing preserved vegetable wastewater, including advanced oxidation-Fenton pretreatment system (I), coarse salt MVR evaporation crystallization system (II) and fine salt MVR evaporation crystallization system (III).The resourceful system needs to be used in cooperation with municipal wastewater treatment plant, after the treatment of the present resourceful system, 5-10% of concentrated mother liquor and evaporated water of feed amount are discharged to municipal wastewater plant for subsequent biochemical treatment, and then discharged.Taking 15% sodium chloride amount in preserved vegetable wastewater, the present system uses two-stage evaporation system of coarse salt-fine salt, which can recover 60-80% of sodium chloride in preserved vegetable wastewater, reaches preserved vegetable salt reuse standard, realizes the resourceful utilization of preserved vegetable wastewater;At the same time, since more than 50% of COD and 60-80% of salt are extracted by the present resourceful system, the organic matter and salt entering municipal wastewater plant are effectively reduced, which effectively protects the flora of municipal wastewater plant and improves stability.

Description

Technical Field

[0001] This invention belongs to the field of high-salt and high-COD wastewater treatment and resource utilization technology, and relates to an MVR evaporation system for synergistic resource utilization treatment of pickled mustard tuber wastewater and a method for synergistic resource utilization treatment of pickled mustard tuber wastewater. Background Technology

[0002] Pickled mustard tuber is a pillar industry of Chongqing and one of the city's distinctive and profitable agricultural sectors. With the rapid economic development of the Three Gorges Reservoir area, its production scale has expanded significantly, resulting in an increasing amount of high-salt, high-concentration, high-nitrogen, and high-phosphorus wastewater generated during its processing, seriously threatening the water environment safety of the reservoir area. The pickled mustard tuber production process and wastewater generation process are as follows: Figure 1 As shown, wastewater from pickled mustard tuber production generates large quantities of wastewater at different stages, such as pickling, washing, desalting, dehydration, and sterilization / cooling. This wastewater is characterized by high salinity and high COD, seriously threatening the water environment safety of the Three Gorges Reservoir area. Furthermore, Chongqing implemented the local standard document "Water Pollutant Discharge Standard for Pickled Mustard Tuber Industry" (DB 50 / 1050-2020) on January 1, 2021, providing an important basis for environmental protection departments at all levels to strengthen the management of water pollutant discharge from pickled mustard tuber production enterprises. According to this standard, the chloride content in pickled mustard tuber wastewater should be controlled below 8000 mg / L. A stricter standard will be implemented in 2025, requiring chloride content to be controlled below 5000 mg / L. Therefore, how to effectively treat pickled mustard tuber wastewater is a matter of great concern. Strengthening the treatment of wastewater from the pickled mustard tuber industry and promoting wastewater reduction and treatment technology innovation in the pickled mustard tuber industry are crucial for cleaner production, wastewater resource utilization, and water environment protection in the Three Gorges Reservoir area.

[0003] Wastewater treatment technologies for pickled mustard tuber can be categorized into physicochemical methods, biological methods, and combined physicochemical-biological processes, with biological and combined physicochemical-biological processes being the primary approaches. These methods include: coagulation sedimentation, electrochemical oxidation, Fenton oxidation, aerated microelectrolysis, iron-carbon microelectrolysis, anaerobic sequencing batch biofilm reactor (ASBBR), sequencing batch biofilm reactor (SBBR), membrane bioreactor (MBR), aerated biofilter, upflow anaerobic sludge blanket reactor (UASB), novel biological rotating cages, and microbial fuel cells, among others. For example, ① Fenton catalytic oxidation technology has mild reaction conditions, high treatment efficiency, and wide applicability. By adjusting parameters such as divalent Fe, hydrogen peroxide, and pH, it can effectively remove phosphates and COD from pickled mustard tuber wastewater. Fenton oxidation is very effective in removing organic matter and phosphates, but its effect on COD removal is limited, and it requires a large amount of H2O2, resulting in high treatment costs. ② Results of microbial fuel cell treatment of pickled mustard tuber wastewater show that the pollutant removal effect is not ideal, and it cannot remove salt. Currently, it still faces problems such as limited domestication of salt-tolerant microorganisms, difficulty in starting anaerobic processes and easy acidification, sensitivity of salt-tolerant bacteria to salinity changes, and significant influence of salinity on biodegradation rates. ③ MBR technology provides a feasible route for efficient biological treatment of saline wastewater due to its forced retention of microorganisms and its lack of limitation on sludge settling. It can effectively remove COD from water, operate stably, resist shock loads, and all indicators of the effluent meet the Class A standard. MBRs play a crucial role in the efficient biological treatment of saline wastewater, but membrane fouling requires close monitoring during operation. Regular chemical cleaning of the membrane fibers using a mixture of NaOH and NaClO is necessary. Other combined treatment methods for pickled mustard tuber wastewater, such as chemical phosphorus removal-hydrolysis acidification-anaerobic contact-contact oxidation processes, UASB-aerobic-coagulation processes, hydrolysis acidification-SBR-coagulation processes, and combined anaerobic / biological phosphorus removal / biological denitrification / chemical phosphorus removal processes, have been applied to phosphorus removal or COD removal, but rarely address the resource recovery of high-salt wastewater. The above methods have all achieved excellent results for wastewater generated after the third pickling process. In particular, pickled mustard tuber wastewater is a conventional food production wastewater, and its organic matter is biodegradable. Even low-salt pickled mustard tuber wastewater can meet standards after biological treatment at municipal wastewater treatment plants.

[0004] The most difficult part to treat is the high-salt, high-COD wastewater from the first, second, and third pickling processes. Although the second and third pickling water can be used to make pickled mustard green soy sauce, its taste is far inferior to regular soy sauce, resulting in low market acceptance. The first and second pickling processes use the largest amounts of salt. In the first pickling, about 4 kg of salt is used per 100 kg of pickled mustard greens, producing a bitter-tasting high-salt brine. In the second pickling, about 10 kg of salt is used per 100 kg of pickled mustard greens, and in the third pickling, about 2 kg of salt is used per 100 kg of pickled mustard greens. All three pickling processes produce high-salt, high-COD wastewater with a salinity greater than 10% and a COD greater than 20,000 ppm. This wastewater is usually discharged into municipal wastewater treatment plants, mixed and diluted with regular domestic sewage, and then treated biologically before being released into the environment. Due to the increasing volume of pickled mustard green wastewater, more and more high-salt, high-COD wastewater is being discharged into municipal wastewater treatment plants, causing significant damage to the biological systems of these plants, and making it difficult to restore the imbalanced microbial flora. Therefore, reducing the amount of salt and organic matter entering wastewater treatment plants is of paramount importance. For example, the process of removing high salt content from pickled mustard tuber wastewater using a coagulation-sedimentation-MVR evaporation-crystallization method is as follows: Figure 2 As shown, the principle is as follows: coagulation and sedimentation are mainly used as a pretreatment process. It primarily utilizes the colloids produced by the chemical reaction of coagulants (PAC, PAM, etc.) to neutralize the opposite charges on the surfaces of certain substances in the pickled mustard tuber wastewater, causing them to flocculate, aggregate, and ultimately settle and separate. It has a high removal rate of suspended solids (>90%), but a relatively low COD removal rate. After further MVR evaporation and crystallization, the resulting recycled salt still contains a high COD, which negatively impacts the taste and safety of the finished pickled mustard tuber product.

[0005] The release of the "Water Pollutant Discharge Standard for the Pickled Mustard Tuber Industry" guides pickled mustard tuber enterprises to address wastewater reduction and treatment technology innovation from three aspects: the source, process, and end of production. This lays the foundation for cleaner production, wastewater resource utilization, and water environment protection in the Three Gorges Reservoir area. At the source, pickled mustard tuber producers should reduce the amount of salt used in the pickling process and increase the reuse rate of brine. Wastewater should be transported to self-built wastewater treatment facilities, industrial park wastewater treatment plants, or urban wastewater treatment plants for treatment, and then discharged into the designated area specified in the discharge permit after reaching the required standards. Direct discharge of wastewater into the environment is strictly prohibited. In the process, pickled mustard tuber producers should adopt technologies to reduce desalination water consumption and reuse or comprehensively utilize high-salinity water. At the end, strict monitoring of pH, chemical oxygen demand, suspended solids, ammonia nitrogen, total phosphorus, and chloride (Cl) in the discharged wastewater is required. - The regulations implement refined management requirements for high-salinity water in the pickled mustard tuber industry, including indicators such as total nitrogen, and apply corresponding water pollutant discharge limits according to different product varieties. Furthermore, pickled mustard tuber wastewater treatment has its own unique characteristics, such as discontinuous discharge, high salt content, high cost of current treatment technologies, and poor stability of existing technologies in achieving standards. These factors have consistently been bottlenecks restricting the treatment of pickled mustard tuber wastewater.

[0006] To address the aforementioned problems with pickled mustard tuber wastewater, this invention considers both the resource utilization of its high salt content and achieving compliant discharge, while also reducing wastewater treatment costs. It provides a MVR evaporation-sewage treatment system for the resource utilization of pickled mustard tuber wastewater. The system mainly includes an advanced oxidation-Fenton pretreatment system to remove organic matter, COD, and odors, facilitating the operation of the subsequent MVR evaporation system; a two-stage MVR evaporation and crystallization system for coarse and refined salt, capable of recovering 60-80% of sodium chloride and ensuring that the recovered salt meets the standard for pickled mustard tuber salt (QB / T 2830-2015), thus realizing the resource utilization of the wastewater. Simultaneously, because over 50% of COD and 60-80% of salt are extracted by this system, the amount of organic matter and salt entering the municipal sewage treatment plant is significantly reduced, significantly minimizing the inhibitory effect on the biological treatment system. This system needs to be used in conjunction with a municipal wastewater treatment plant. 5-10% of the concentrated mother liquor and distilled water from the evaporation system will be discharged to the municipal wastewater treatment plant for further biochemical treatment before being discharged. Summary of the Invention

[0007] In view of this, in order to solve the problem that the high-salt and high-COD wastewater from pickled mustard tubers cannot be directly treated in urban sewage treatment plants, the present invention provides an MVR evaporation system for the synergistic resource-based treatment of pickled mustard tuber wastewater and a method for the synergistic resource-based treatment of pickled mustard tuber wastewater.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] 1. An MVR evaporation system for synergistic resource-based treatment of pickled mustard tuber wastewater, the MVR evaporation system comprising an advanced oxidation-Fenton pretreatment system (I), a crude salt MVR evaporation crystallization system (II), and a refined salt MVR evaporation crystallization system (III) connected in sequence;

[0010] The advanced oxidation-Fenton pretreatment system (I) includes a raw material storage tank 3, a Fenton reaction tank 11, a neutralization tank 14 and a horizontal screw centrifuge 19 connected in sequence. The Fenton reaction tank 11 is connected to an H2O2 storage tank 1A and a FeCl2 storage tank 1C. The neutralization tank 14 is connected to a NaOH storage tank 1D and a compressed air pipe 16. The Fenton reaction tank outlet 12 of the Fenton reaction tank 11 is connected to the neutralization tank inlet 15 of the neutralization tank 14.

[0011] The crude salt MVR evaporation crystallization system (II) includes a crude salt MVR feed tank 22, a crude salt MVR separator 30, and a crude salt MVR solid-liquid separation centrifuge 28 connected in sequence.

[0012] The refined salt MVR evaporation crystallization system (III) includes a crude salt dissolving tank 35, a refined salt MVR feed tank 36, a refined salt MVR separator 44, and a refined salt MVR solid-liquid separation centrifuge 42 connected in sequence.

[0013] The clear liquid outlet 20 of the horizontal screw centrifuge 19 in the advanced oxidation-Fenton pretreatment system (I) is connected to the inlet of the crude salt MVR feed tank 22 in the crude salt MVR evaporation crystallization system (II). The outlet of the crude salt MVR solid-liquid separation centrifuge 28 in the crude salt MVR evaporation crystallization system (II) is connected to the inlet of the urban sewage treatment system and the crude salt dissolving tank 35 in the refined salt MVR evaporation crystallization system (III). The outlet of the refined salt MVR solid-liquid separation centrifuge 42 in the refined salt MVR evaporation crystallization system (III) is connected to the urban sewage treatment system.

[0014] Preferably, the top inlet of the Fenton reactor 11 includes an H2O2 inlet pipe 9 and an FeCl2 inlet pipe 10 leading to the bottom of the Fenton reactor 11, wherein an H2O2 diaphragm pump 2A is provided between the H2O2 inlet pipe 9 and the H2O2 storage tank 1A, and an FeCl2 diaphragm pump 2D is provided between the FeCl2 inlet pipe 10 and the FeCl2 storage tank 1C;

[0015] The side inlet of the Fenton reactor 11 includes a raw material inlet pipe 8 leading to the bottom of the Fenton reactor 11. The raw material inlet pipe 8 is connected to the pipeline mixer 6 and a first pH meter 7A is installed in the middle. The pipeline mixer 6 is connected to the HCl storage tank 1B and the raw material storage pool 3 respectively. An advanced oxidation feed pump 2C is installed between the raw material storage pool 3 and the pipeline mixer 6. A raw material storage pool level gauge 4A is installed in the raw material storage pool 3. An HCl diaphragm pump 2B is installed between the HCl storage tank 1B and the pipeline mixer 6.

[0016] The Fenton reaction vessel outlet 12 on the other side of the Fenton reaction vessel 11 is connected to the neutralization vessel inlet 15 of the neutralization vessel 14, and the neutralization vessel outlet 18 of the neutralization vessel 14 is connected to the horizontal screw centrifuge 19.

[0017] The top of the Fenton reaction vessel 11 is equipped with a first variable frequency stirrer 13A and a Fenton reaction vessel level gauge 4B, and the side of the Fenton reaction vessel 11 is equipped with a second pH meter 7B.

[0018] The top inlet of the neutralization tank 14 includes a compressed air pipe 16 and a NaOH pipe 17 that lead to the bottom of the neutralization tank 14. The NaOH pipe 17 is connected to the NaOH storage tank 1D and is equipped with a NaOH diaphragm pump 2E.

[0019] The neutralization tank 14 is equipped with a second variable frequency stirrer 13B and a neutralization tank level gauge 4C at the top, and the neutralization tank 14 is equipped with a third pH meter 7C.

[0020] The horizontal screw centrifuge 19 is provided with a solid outlet 21 and a clear liquid outlet 20. The clear liquid outlet 20 of the horizontal screw centrifuge 19 is connected to the crude salt MVR feed tank 22 in the crude salt MVR evaporation crystallization system (II). The crude salt MVR feed tank 22 is provided with a clear liquid tank level gauge 4D.

[0021] Preferably, the crude salt MVR separator 30 is composed of an upper crude salt MVR crystallizer 31 and a lower crude salt MVR crystallization leg 32 connected together, and a crude salt MVR discharge circulation pump 26 is provided between the crude salt MVR crystallizer 31 and the crude salt MVR crystallization leg 32.

[0022] The crude salt MVR crystallizer 31 is connected to the top and bottom of the crude salt MVR heater 29 respectively. A crude salt MVR forced circulation pump 25 is provided between the bottom of the crude salt MVR heater 29 and the crude salt MVR crystallizer 31. The lower part of the crude salt MVR heater 29 is connected to the crude salt MVR condensate negative pressure pump 24.

[0023] The crude salt MVR crystallizer 31 is connected to the crude salt MVR cyclone separator 33 and the crude salt MVR cyclone separator demister 34 respectively. The crude salt MVR cyclone separator demister 34 is connected to the crude salt MVR cyclone separator 33 located directly below. A crude salt MVR steam compressor 27 is provided between the crude salt MVR cyclone separator demister 34 and the crude salt MVR crystallizer 31.

[0024] A crude salt MVR feed pump 23 is provided between the crude salt MVR feed tank 22 and the crude salt MVR crystallizer 31.

[0025] Preferably, the refined salt MVR separator 44 consists of an upper refined salt MVR crystallizer 45 and a refined salt MVR crystallization leg 46 located directly below;

[0026] A refined salt MVR discharge circulation pump 40 is provided between the refined salt MVR crystallizer 45 and the refined salt MVR crystallization leg 46.

[0027] The refined salt MVR crystallizer 45 is connected to the top and bottom of the refined salt MVR heater 43 respectively. A refined salt MVR forced circulation pump 39 is provided between the bottom of the refined salt MVR heater 43 and the refined salt MVR crystallizer 45. The lower part of the refined salt MVR heater 43 is connected to the refined salt MVR condensate negative pressure pump 38.

[0028] The refined salt MVR crystallizer 45 is connected to the refined salt MVR cyclone separator 47 and the refined salt MVR cyclone separator demister 48 respectively. The refined salt MVR cyclone separator demister 48 is connected to the refined salt MVR cyclone separator 47 located directly below. A refined salt MVR steam compressor 41 is provided between the refined salt MVR cyclone separator demister 48 and the refined salt MVR crystallizer 45.

[0029] The crude salt dissolving tank 35 is equipped with a crude salt dissolving tank level gauge 4E on its side and a third variable frequency stirrer 13C on its top.

[0030] A refined salt MVR feed tank level gauge 4F is provided on the side of the refined salt MVR feed tank 36, and a refined salt MVR feed pump 37 is provided between the refined salt MVR feed tank 36 and the refined salt MVR crystallizer 45.

[0031] Preferably, the outlet of the crude salt MVR solid-liquid separation centrifuge 28 and the refined salt MVR solid-liquid separation centrifuge 42 are respectively connected to the mother liquor inlet 5 in the raw material storage tank 3.

[0032] 2. A method for the synergistic resource-based treatment of pickled mustard tuber wastewater, wherein the method is carried out using the above-mentioned apparatus and specifically includes the following steps:

[0033] (1) In the advanced oxidation-Fenton pretreatment system (I), the HCl solution in the HCl storage tank (1B) and the pickled mustard wastewater to be treated in the raw material storage tank (3) are mixed in the pipeline mixer (6). After the pH is adjusted to 3-4 by the first pH meter (7A), it is introduced into the bottom of the Fenton reaction tank (11) to react with the H2O2 introduced into the bottom of the Fenton reaction tank (11) from the H2O2 storage tank (1A) and the FeCl2 introduced into the bottom of the Fenton reaction tank (11) from the FeCl2 storage tank (1C). The reaction ends. Then it enters the bottom of the neutralization tank (14) and reacts with the NaOH solution that enters the bottom of the neutralization tank (14) from the NaOH storage tank (1D). The third pH meter (7C) set in the neutralization tank (14) adjusts the pH of the reaction process. After the reaction is completed, the liquid overflows from the upper outlet (18) of the neutralization tank (14) into the horizontal screw centrifuge (19) to achieve solid-liquid separation. The solid is discharged from the solid outlet (21), and the liquid enters the crude salt MVR feed tank (22) of the crude salt MVR evaporation crystallization system (II) through the clear liquid outlet (20).

[0034] (2) In the crude salt MVR evaporation crystallization system (II), the crude salt in the crude salt MVR feed tank (22) is pumped into the crude salt MVR crystallizer (31) of the crude salt MVR separator (30) for evaporation crystallization. The crude salt crystallizer is precipitated from the lower crude salt MVR crystallization leg (32) and enters the crude salt MVR discharge circulation pump (26). The liquid part enters the connected urban sewage treatment system, and the solid part enters the crude salt dissolving tank (35) in the refined salt MVR evaporation crystallization system (III).

[0035] (3) In the refined salt MVR evaporation crystallization system (III), crude salt is mixed and dissolved with water in the crude salt dissolving tank (35) and then enters the refined salt MVR feed tank (36). It then enters the refined salt MVR crystallizer (45) for evaporation crystallization. It enters the refined salt MVR solid-liquid separation centrifuge (42) from the crystallization leg (46) below. The liquid part enters the connected urban sewage treatment system, and the solid part is the refined salt for recycling.

[0036] Preferably, an HCl diaphragm pump (2B) is installed between the HCl storage tank (1B) and the pipeline mixer (6). The HCl diaphragm pump (2B) is linked with the first pH meter (7A) to adjust the pH. Specifically, by setting the pH value of the first pH meter (7A) to 3.5, the feed rate is adjusted by the HCl diaphragm pump (2B) so that the pH of the mixed liquid is 3 to 4.

[0037] A NaOH diaphragm pump (2E) is installed between the NaOH storage tank (1D) and the neutralization tank (14). The NaOH diaphragm pump (2E) is linked with the third pH meter (7C) to adjust the pH. Specifically, the feed rate is adjusted by setting the pH value of the third pH meter (7C) to 7.5 and then adjusting the feed rate through the NaOH diaphragm pump (2E).

[0038] Preferably, the volume ratio of crude salt to water in the crude salt dissolving tank (35) is 1:3 to 4.

[0039] The beneficial effects of the present invention are as follows: The present invention discloses an MVR evaporation system for synergistic resource recovery treatment of pickled mustard tuber wastewater, which has a good treatment effect on pickled mustard tuber wastewater, mainly reflected in: (1) The system of the present invention is equipped with an advanced oxidation-Fenton system, which can first remove 50% of the organic matter in the high-salt and high-COD pickled mustard tuber wastewater, that is, reduce the organic matter entering the subsequent urban sewage treatment plant by 50%; secondly, the advanced oxidation-Fenton system can eliminate the COD and odor of the pickled mustard tuber wastewater, so that the subsequent salt that meets the salt standard for pickled mustard tuber can be obtained and reused in the production of pickled mustard tuber, realizing the resource recovery of pickled mustard tuber wastewater; finally, the removal of organic matter makes the subsequent evaporation crystallization system run smoothly, eliminating the risk of foaming and pipe blockage during evaporation. (2) The system of the present invention is equipped with a crude salt MVR evaporation crystallization system and a refined salt MVR evaporation crystallization system. Crude salt is obtained from the crude salt MVR evaporation crystallization system, and then refined salt is obtained from the crude salt MVR evaporation crystallization system. The refined salt can meet the salt standard for pickled mustard tuber (QB / T2830-2015 Pickled Mustard Tuber Salt), and the resource recovery rate is greater than 60%. (3) The crude salt MVR evaporation crystallization system and the refined salt MVR evaporation crystallization system of this invention adopt a cyclone separator with a wire mesh demisting device. The salt content in the steam is low, which can effectively protect the steam compressor. At the same time, the condensate after evaporation is very pure. (4) The crude salt MVR evaporation crystallization system and the refined salt MVR evaporation crystallization system of this invention use evaporation at a temperature of 60-70℃. Except for the steam required for the steam compressor sealing, no additional steam supply is required. It can achieve 60-70 kWh of electric evaporation to evaporate one ton of water.

[0040] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0041] Figure 1 A flowchart illustrating the production process and pollution generation of pickled mustard tuber.

[0042] Figure 2 The flowchart shows the process of removing high salt content from pickled mustard tuber wastewater using a coagulation-sedimentation-MVR evaporation-crystallization method.

[0043] Figure 3 This is a structural diagram of the MVR evaporation system for the synergistic resource-based treatment of pickled mustard tuber wastewater according to the present invention;

[0044] Figure 4 This is a structural diagram of the advanced oxidation-Fenton pretreatment system (I) of the present invention;

[0045] Figure 5This is a structural diagram of the crude salt MVR evaporation crystallization system (II) of the present invention;

[0046] Figure 6 This is a structural diagram of the refined salt MVR evaporation crystallization system (III) of the present invention;

[0047] Figure 7 A flowchart illustrating the process of treating high-salt pickled mustard tuber wastewater from Dianjiang County, Chongqing City using the MVR evaporation system of this invention for synergistic resource recovery treatment of pickled mustard tuber wastewater;

[0048] Figure 8 A flowchart for treating wastewater from pickled mustard tubers in a laboratory setting;

[0049] Wherein, 1A is an H2O2 storage tank, 1B is an HCl storage tank, 1C is a FeCl2 storage tank, 1D is a NaOH storage tank, 2A is an H2O2 diaphragm pump, 2B is an HCl diaphragm pump, 2C is an advanced oxidation feed pump, 2D is a FeCl2 diaphragm pump, 2E is a NaOH diaphragm pump, 3 is a raw material storage tank, 4A is a raw material storage tank level gauge, 4B is a Fenton reaction tank level gauge, 4C is a neutralization tank level gauge, 4D is a clearing liquid tank level gauge, 4E is a crude salt dissolving tank level gauge, 4F is a refined salt MVR feed tank level gauge, 5 is a mother liquor inlet, and 6 is a pipeline. Mixer, 7A is the first pH meter, 7B is the second pH meter, 7C is the third pH meter, 8 is the raw material inlet pipe, 9 is the H2O2 inlet pipe, 10 is the FeCl2 inlet pipe, 11 is the Fenton reaction vessel, 12 is the Fenton reaction vessel outlet, 13A is the first variable frequency stirrer, 13B is the second variable frequency stirrer, 13C is the third variable frequency stirrer, 14 is the neutralization tank, 15 is the neutralization tank inlet, 16 is the compressed air pipe, 17 is the NaOH pipe, 18 is the neutralization tank outlet, 19 is the horizontal screw centrifuge, 20 is the horizontal screw centrifuge supernatant outlet, 21 is the horizontal screw centrifuge outlet, 22 is the solid outlet of the screw centrifuge; 23 is the feed tank for crude salt MVR; 24 is the feed pump for crude salt MVR; 25 is the negative pressure pump for crude salt MVR condensate; 26 is the forced circulation pump for crude salt MVR; 27 is the discharge circulation pump for crude salt MVR; 28 is the steam compressor for crude salt MVR; 29 is the solid-liquid separation centrifuge for crude salt MVR; 30 is the heater for crude salt MVR; 31 is the separator for crude salt MVR; 32 is the crystallizer for crude salt MVR; 33 is the crystallization leg for crude salt MVR; 34 is the demister for the cyclone separator for crude salt MVR. 35 is a crude salt dissolving tank, 36 is a refined salt MVR feed tank, 37 is a refined salt MVR feed pump, 38 is a refined salt MVR condensate negative pressure pump, 39 is a refined salt MVR forced circulation pump, 40 is a refined salt MVR discharge circulation pump, 41 is a refined salt MVR steam compressor, 42 is a refined salt MVR solid-liquid separation centrifuge, 43 is a refined salt MVR heater, 44 is a refined salt MVR separator, 45 is a refined salt MVR crystallizer, 46 is a refined salt MVR crystallization leg, 47 is a refined salt MVR cyclone separator, and 48 is a refined salt MVR cyclone separator demisting device. Detailed Implementation

[0050] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0051] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0052] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0053] Example 1:

[0054] An MVR evaporation system for the synergistic resource-based treatment of pickled mustard tuber wastewater has the following structure: Figure 3 As shown, the MVR evaporation system in this system includes an advanced oxidation-Fenton pretreatment system (I) connected in sequence (as shown in the figure). Figure 4 As shown, it includes a raw material storage tank 3, a Fenton reaction tank 11, a neutralization tank 14, and a horizontal screw centrifuge 19 connected in sequence. The Fenton reaction tank 11 is connected to an H2O2 storage tank 1A and an HCl storage tank 1B, and the neutralization tank 14 is connected to a NaOH storage tank 1D. It also includes a crude salt MVR evaporation crystallization system (II) (as shown). Figure 5 As shown, it includes a crude salt MVR feed tank 22, a crude salt MVR separator 30, and a crude salt MVR solid-liquid separation centrifuge 28 connected in sequence, and a refined salt MVR evaporation crystallization system (III) (as shown). Figure 6As shown, it includes a crude salt dissolving tank 35, a refined salt MVR feed tank 36, a refined salt MVR separator 44, and a refined salt MVR solid-liquid separation centrifuge 42 connected in sequence.

[0055] In the aforementioned advanced oxidation-Fenton pretreatment system (I), the top inlet of the Fenton reactor 11 includes an H2O2 inlet pipe 9 and an FeCl2 inlet pipe 10 leading to the bottom of the Fenton reactor 11. An H2O2 diaphragm pump 2A is installed between the H2O2 inlet pipe 9 and the H2O2 storage tank 1A, and an FeCl2 diaphragm pump 2D is installed between the FeCl2 inlet pipe 10 and the FeCl2 storage tank 1C. A side inlet on one side of the Fenton reactor 11 includes a raw material inlet pipe 8 leading to the bottom of the Fenton reactor 11. The raw material inlet pipe 8 is connected to a pipe mixer 6 and has a first pH meter 7A installed in the middle. The pipe mixer 6 is connected to an HCl storage tank 1B and a raw material storage tank 3, respectively. An advanced oxidation feed pump 2C is installed between the raw material storage tank 3 and the pipe mixer 6. A raw material storage tank level gauge 4A is installed in the raw material storage tank 3. An HCl diaphragm pump 2B is installed between the HCl storage tank 1B and the pipe mixer 6. The other side of the Fenton reactor 11... The outlet 12 of the Fenton reaction tank is connected to the inlet 15 of the neutralization tank 14, and the outlet 18 of the neutralization tank 14 is connected to the horizontal screw centrifuge 19; the top of the Fenton reaction tank 11 is equipped with a first variable frequency stirrer 13A and a Fenton reaction tank level gauge 4B, and the side of the Fenton reaction tank 11 is equipped with a second pH meter 7B; the top inlet of the neutralization tank 14 contains a compressed air pipe 16 and a NaOH pipe 17 leading to the bottom of the neutralization tank 14, wherein the NaOH pipe 17 is connected to the NaOH storage tank 1. D is connected and equipped with a NaOH diaphragm pump 2E; the top of the neutralization tank 14 is equipped with a second variable frequency stirrer 13B and a neutralization tank level gauge 4C, and the neutralization tank 14 is equipped with a third pH meter 7C; the horizontal screw centrifuge 19 is equipped with a solid outlet 21 and a clear liquid outlet 20, and the clear liquid outlet 20 of the horizontal screw centrifuge 19 is connected to the crude salt MVR feed tank 22 in the crude salt MVR evaporation crystallization system (II), wherein the crude salt MVR feed tank 22 is equipped with a clear liquid tank level gauge 4D.

[0056] In the aforementioned crude salt MVR evaporation crystallization system (II), the crude salt MVR separator 30 is composed of an upper crude salt MVR crystallizer 31 and a lower crude salt MVR crystallization leg 32 connected together. A crude salt MVR discharge circulation pump 26 is provided between the crude salt MVR crystallizer 31 and the crude salt MVR crystallization leg 32. The crude salt MVR crystallizer 31 is connected to the top and bottom of the crude salt MVR heater 29, respectively. A crude salt MVR forced circulation pump 25 is provided between the bottom of the crude salt MVR heater 29 and the crude salt MVR crystallizer 31. The lower part is connected to the negative pressure pump 24 for condensate of the crude salt MVR; the crude salt MVR crystallizer 31 is connected to the crude salt MVR cyclone separator 33 and the crude salt MVR cyclone separator demister 34 respectively, wherein the crude salt MVR cyclone separator demister 34 is connected to the crude salt MVR cyclone separator 33 located directly below, and a crude salt MVR steam compressor 27 is provided between the crude salt MVR cyclone separator demister 34 and the crude salt MVR crystallizer 31; a crude salt MVR feed pump 23 is provided between the crude salt MVR feed tank 22 and the crude salt MVR crystallizer 31.

[0057] In the above-mentioned refined salt MVR evaporation crystallization system (III), the refined salt MVR separator 44 consists of an upper refined salt MVR crystallizer 45 and a refined salt MVR crystallization leg 46 located directly below; a refined salt MVR discharge circulation pump 40 is provided between the refined salt MVR crystallizer 45 and the refined salt MVR crystallization leg 46; the refined salt MVR crystallizer 45 is connected to the top and bottom of the refined salt MVR heater 43, wherein a refined salt MVR forced circulation pump 39 is provided between the bottom of the refined salt MVR heater 43 and the refined salt MVR crystallizer 45, and the lower part of the refined salt MVR heater 43 is connected to a refined salt MVR condensate negative pressure pump 38; the refined salt MVR crystallizer 45 is connected to the top and bottom of the refined salt MVR heater 43, wherein a refined salt MVR forced circulation pump 39 is provided between the bottom of the refined salt MVR heater 43 and the refined salt MVR crystallizer 45, and a refined salt MVR condensate negative pressure pump 38 is connected to the refined salt MVR heater 43; the refined salt MVR crystallizer 45 is connected to the top and bottom of the refined salt MVR heater 43, wherein a refined salt MVR forced circulation pump 39 is provided between the bottom of the refined salt MVR heater 43 and the refined salt MVR condensate negative pressure pump 38; the refined salt MVR crystallizer 45 is connected to the top and bottom of the refined salt MVR heater 43, wherein a refined salt MVR condensate negative pressure pump 38 is connected to the refined salt MVR heater 43, wherein a refined salt MVR crystallizer 45 is connected to the refined salt MVR heater 45, wherein a refined salt MVR condensate negative pressure pump 38 is connected to the refined salt MVR heater 45, wherein a refined salt MVR condensate negative pressure pump 38 is connected to the refined salt MVR heater 45, wherein a refined salt The refined salt MVR cyclone separator 47 and the refined salt MVR cyclone separator demister 48 are connected, wherein the refined salt MVR cyclone separator demister 48 is connected to the refined salt MVR cyclone separator 47 located directly below it, and a refined salt MVR steam compressor 41 is provided between the refined salt MVR cyclone separator demister 48 and the refined salt MVR crystallizer 45; a crude salt dissolving tank level gauge 4E is provided on the side of the crude salt dissolving tank 35 and a third variable frequency stirrer 13C is provided on the top; a refined salt MVR feed tank level gauge 4F is provided on the side of the refined salt MVR feed tank 36, wherein a refined salt MVR feed pump 37 is provided between the refined salt MVR feed tank 36 and the refined salt MVR crystallizer 45.

[0058] In addition, in order to further recover refined salt for recycling, the outlet of the crude salt MVR solid-liquid separation centrifuge 28 and the refined salt MVR solid-liquid separation centrifuge 42 are connected to the mother liquor inlet 5 in the raw material storage tank 3, so that the liquid generated by centrifugation in the crude salt MVR solid-liquid separation centrifuge 28 and the refined salt MVR solid-liquid separation centrifuge 42 can re-enter the raw material storage tank 3 in the form of livestock for the next round of processing.

[0059] The MVR evaporation system for the synergistic resource recovery treatment of pickled mustard tuber wastewater is used to treat the wastewater. The specific treatment steps are as follows:

[0060] (1) In the advanced oxidation-Fenton pretreatment system (I), the HCl solution in the HCl storage tank 1B and the pickled mustard wastewater to be treated in the raw material storage tank 3 are mixed, the pH is adjusted to 3-4 and then introduced into the bottom of the Fenton reaction tank 11, and the Fenton reaction occurs with the H2O2 introduced into the bottom of the Fenton reaction tank 11 from the H2O2 storage tank 1A and the FeCl2 introduced into the bottom of the Fenton reaction tank 11 from the FeCl2 storage tank 1C. After the reaction, the solution enters the bottom of the neutralization tank 14 and undergoes a neutralization reaction with the NaOH solution introduced into the bottom of the neutralization tank 14 from the NaOH storage tank 1D. After the reaction, the liquid overflows from the upper outlet 18 of the neutralization tank 14 into the horizontal screw centrifuge 19 to achieve solid-liquid separation. The solid is discharged from the solid outlet 21 and the liquid enters the crude salt MVR feed tank 22 of the crude salt MVR evaporation crystallization system (II) through the clear liquid outlet 20.

[0061] (2) In the crude salt MVR evaporation crystallization system (II), the crude salt in the crude salt MVR feed tank 22 is pumped into the crude salt MVR crystallizer 31 of the crude salt MVR separator 30 for evaporation crystallization. The crude salt crystallizer 32 below is precipitated into the crude salt MVR discharge circulation pump 26. The liquid part enters the connected urban sewage treatment system, and the solid part enters the crude salt dissolving tank 35 in the refined salt MVR evaporation crystallization system (III).

[0062] (3) In the refined salt MVR evaporation crystallization system (III), crude salt is dissolved in crude salt dissolving tank 35 by mixing with water (volume ratio of 1:3 to 4) and then enters refined salt MVR feed tank 36. It then enters refined salt MVR crystallizer 45 for evaporation crystallization. It enters refined salt MVR solid-liquid separation centrifuge 42 from the refined salt MVR crystallization leg 46 below. The liquid part enters the connected urban sewage treatment system, and the solid part is refined salt for recycling.

[0063] In the above method, the HCl diaphragm pump 2B is linked with the first pH meter 7A. Specifically, by setting the pH value of the first pH meter 7A to 3.5, the feed rate is adjusted by the HCl diaphragm pump 2B to make the pH of the mixed solution 3-4. The NaOH diaphragm pump 2E is linked with the third pH meter 7C. Specifically, by setting the pH value of the third pH meter 7C to 7.5, the feed rate is adjusted by the NaOH diaphragm pump 2E.

[0064] Example 2

[0065] The system and method described in Example 1 above were used to treat high-salt wastewater from pickled mustard tuber processing in Dianjiang County, Chongqing. The process is as follows: Figure 7 As shown in Table 1, the results are described in detail below:

[0066] 1. The high-salt wastewater from this pickled mustard tuber processing plant originated from a pickled mustard tuber factory in Dianjiang County, Chongqing. The wastewater had a COD of 22600 mg / L and a NaCl content of 1.41 × 10⁻⁶ mg / L. 5 The wastewater, with a concentration of mg / L, a bluish-green color, a pH of 4.8, and a pungent odor, was treated by adjusting the pH to 3-4 with 1 mol / L HCl solution. Then, FeCl2·4H2O and H2O2 were added to initiate the Fenton reaction. After the Fenton reaction was complete, 1 mol / L NaOH solution was added to adjust the pH to 7-8 for flocculation. After standing and flocculation, the mixture was filtered. The catalysts H2O2 and FeCl2 in the Fenton reaction... 2+ The specific molar ratios are shown in Table 1. After testing, the COD of the filtrate following the Fenton reaction decreased from 22600 mg / L to 17420–10120 mg / L, indicating that the Fenton reaction significantly removes COD from wastewater. Furthermore, the treated water sample showed no odor. Considering both COD removal efficiency and economic efficiency, sample number 4, with the lowest dosage of hydrogen peroxide and ferrous chloride, represents the optimal condition. Therefore, this process condition was selected for subsequent evaporation, crystallization, and salt extraction.

[0067] 2. The subsequent advanced oxidation Fenton reaction was carried out under the experimental conditions specified in No. 4. Specifically, 200 ml of 1 mol / L HCl solution was added to 3 L of wastewater to adjust the pH value to 3.4. Then, 5.12 g of FeCl2·4H2O (0.025 mol) was added and stirred until fully dissolved. Then, 300 ml of 3 wt% H2O2 (0.25 mol) was slowly added while stirring. After the addition was completed, the reaction was allowed to proceed for 120 min. After the Fenton reaction was completed, 260 ml of 1 mol / L NaOH solution was added to adjust the pH value to 7.4 for flocculation. After standing and flocculation, the mixture was filtered.

[0068] 3. After the Fenton oxidation reaction is completed and filtered, the filtrate is evaporated and crystallized to obtain yellowish crude salt and distillate condensate. The distillate condensate may contain high COD and cannot be discharged indiscriminately to avoid polluting the environment. This part can be discharged into a municipal wastewater treatment plant for advanced treatment.

[0069] 4. Crude salt is dissolved, evaporated, and crystallized to obtain white refined salt. The finished salt, obtained using a process of advanced oxidation followed by crude salt evaporation, concentration, and crystallization, has a purity of 97.8% and a whiteness of 70. No nitrite or potassium ferrocyanide was detected. According to the QB / T2830-2015 standard for pickled mustard greens salt, the finished salt can be reused in the production of pickled mustard greens. In the experiment, 3L of pickled mustard greens wastewater yielded 280g of finished salt (salt extraction rate of 65%). At the end of the process, 200ml of mother liquor remained. This small amount of mother liquor is a saturated sodium chloride solution, and its COD is also highly concentrated. It can be discharged into a municipal wastewater treatment plant for further treatment; therefore, the COD value of the mother liquor was not tested in this experiment.

[0070] Table 1. Fenton's test conditions and results for pickled mustard tuber wastewater.

[0071]

[0072] This shows that compared to the treatment process of pickled mustard tuber wastewater in the laboratory (such as...), Figure 8 As shown), this invention discloses an MVR evaporation system for the synergistic resource recovery treatment of pickled mustard tuber wastewater, which has a good treatment effect on pickled mustard tuber wastewater, mainly reflected in: (1) The system of this invention is equipped with an advanced oxidation-Fenton system, which can first remove 50% of the organic matter in the high-salt and high-COD pickled mustard tuber wastewater, that is, reduce the organic matter entering the subsequent urban sewage treatment plant by 50%; secondly, the advanced oxidation-Fenton system can eliminate the COD and odor of the pickled mustard tuber wastewater, so that the subsequent salt that meets the salt standard for pickled mustard tuber can be obtained and reused in the production of pickled mustard tuber, realizing the resource recovery of pickled mustard tuber wastewater; finally, the removal of organic matter makes the subsequent evaporation crystallization system run smoothly, eliminating the risk of foaming and pipe blockage during evaporation. (2) The system of this invention is equipped with a crude salt MVR evaporation crystallization system and a refined salt MVR evaporation crystallization system. Crude salt is obtained from the crude salt MVR evaporation crystallization system, and then refined salt is obtained from the crude salt MVR evaporation crystallization system. The refined salt can meet the salt standard for pickled mustard tuber (QB / T 2830-2015 Pickled Mustard Tuber Salt), and the resource recovery rate is greater than 60%. (3) The crude salt MVR evaporation crystallization system and the refined salt MVR evaporation crystallization system of this invention adopt a cyclone separator with a wire mesh demisting device. The salt content in the steam is low, which can effectively protect the steam compressor. At the same time, the condensate after evaporation is very pure. (4) The crude salt MVR evaporation crystallization system and the refined salt MVR evaporation crystallization system of this invention use evaporation at a temperature of 60-70℃. Except for the steam required for the steam compressor sealing, no additional steam supply is required. It can achieve 60-70 kWh of electric evaporation to evaporate one ton of water.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A MVR evaporation system for synergistically treating preserved vegetable wastewater, characterized in that, The MVR evaporation system comprises a high-level oxidation-Fenton pretreatment system (I), a coarse salt MVR evaporation crystallization system (II) and a fine salt MVR evaporation crystallization system (III) connected in sequence. The high-level oxidation-Fenton pretreatment system (I) comprises a raw material storage tank (3), a Fenton reaction tank (11), a neutralization tank (14) and a horizontal screw centrifuge (19) connected in sequence, wherein the Fenton reaction tank (11) is connected with an H2O2 storage tank (1A) and an FeCl2 storage tank (1C), the neutralization tank (14) is connected with an NaOH storage tank (1D) and a compressed air pipe (16), and the Fenton reaction tank outlet (12) of the Fenton reaction tank (11) is connected with the neutralization tank inlet (15) of the neutralization tank (14); The coarse salt MVR evaporation crystallization system (II) comprises a coarse salt MVR feed tank (22), a coarse salt MVR separator (30) and a coarse salt MVR solid-liquid separation centrifuge (28) connected in sequence; The fine salt MVR evaporation crystallization system (III) comprises a coarse salt dissolving tank (35), a fine salt MVR feed tank (36), a fine salt MVR separator (44) and a fine salt MVR solid-liquid separation centrifuge (42) connected in sequence; The clear liquid outlet (20) of the horizontal screw centrifuge (19) in the high-level oxidation-Fenton pretreatment system (I) is connected with the inlet of the coarse salt MVR feed tank (22) in the coarse salt MVR evaporation crystallization system (II), the outlet of the coarse salt MVR solid-liquid separation centrifuge (28) in the coarse salt MVR evaporation crystallization system (II) is connected with the inlet of the coarse salt dissolving tank (35) in the fine salt MVR evaporation crystallization system (III) and the urban sewage treatment system, and the outlet of the fine salt MVR solid-liquid separation centrifuge (42) in the fine salt MVR evaporation crystallization system (III) is connected with the urban sewage treatment system; The outlets of the coarse salt MVR solid-liquid separation centrifuge (28) and the fine salt MVR solid-liquid separation centrifuge (42) are respectively connected with the mother liquor inlet (5) in the raw material storage tank (3); The top inlet of the Fenton reaction tank (11) comprises an H2O2 inlet pipe (9) and an FeCl2 inlet pipe (10) connected with the bottom of the Fenton reaction tank (11), wherein an H2O2 diaphragm pump (2A) is arranged between the H2O2 inlet pipe (9) and the H2O2 storage tank (1A), and an FeCl2 diaphragm pump (2D) is arranged between the FeCl2 inlet pipe (10) and the FeCl2 storage tank (1C); The side inlet of one side of the Fenton reaction tank (11) comprises a raw material inlet pipe (8) connected with the bottom of the Fenton reaction tank (11), wherein the raw material inlet pipe (8) is connected with a pipeline mixer (6) and a first pH meter (7A) is arranged in the middle, the pipeline mixer (6) is connected with an HCl storage tank (1B) and a raw material storage tank (3), a high-level oxidation feed pump (2C) is arranged between the raw material storage tank (3) and the pipeline mixer (6), the raw material storage tank (3) is provided with a raw material storage tank liquid level meter (4A), and an HCl diaphragm pump (2B) is arranged between the HCl storage tank (1B) and the pipeline mixer (6); The Fenton reaction tank (11) on the other side of the Fenton reaction tank outlet (12) is connected with the neutralization tank inlet (15) of the neutralization tank (14), and the neutralization tank outlet (18) of the neutralization tank (14) is connected with the horizontal screw centrifuge (19); The Fenton reaction tank (11) is provided with a first variable frequency stirrer (13A) and a Fenton reaction tank liquid level meter (4B) on the top, and is provided with a second pH meter (7B) on the side; The top inlet of the neutralization tank (14) contains a compressed air pipe (16) and a NaOH pipe (17) leading into the bottom of the neutralization tank (14), wherein the NaOH pipe (17) is connected with the NaOH storage tank (1D) and is provided with a NaOH diaphragm pump (2E); The neutralization tank (14) is provided with a second variable frequency stirrer (13B) and a neutralization tank liquid level meter (4C) on the top, and is provided with a third pH meter (7C); The horizontal screw centrifuge (19) is provided with a solid outlet (21) and a clear liquid outlet (20), and the clear liquid outlet (20) of the horizontal screw centrifuge (19) is connected with the coarse salt MVR feed tank (22) in the coarse salt MVR evaporation crystallization system (II), wherein the coarse salt MVR feed tank (22) is provided with a clear material liquid tank liquid level meter (4D).

2. The MVR evaporation system of claim 1, wherein, The coarse salt MVR separator (30) is composed of a coarse salt MVR crystallizer (31) on the top and a coarse salt MVR crystallization leg (32) below, and a coarse salt MVR discharge circulating pump (26) is arranged between the coarse salt MVR crystallizer (31) and the coarse salt MVR crystallization leg (32); The coarse salt MVR crystallizer (31) is connected with the top end and the bottom of the coarse salt MVR heater (29) respectively, wherein a coarse salt MVR forced circulation pump (25) is arranged between the bottom of the coarse salt MVR heater (29) and the coarse salt MVR crystallizer (31), and the lower part of the coarse salt MVR heater (29) is connected with the coarse salt MVR condensate water negative pressure pump (24); The coarse salt MVR crystallizer (31) is connected with the coarse salt MVR cyclone separator (33) and the coarse salt MVR cyclone separator demisting device (34) respectively, wherein the coarse salt MVR cyclone separator demisting device (34) is communicated with the coarse salt MVR cyclone separator (33) located directly below, and a coarse salt MVR steam compressor (27) is arranged between the coarse salt MVR cyclone separator demisting device (34) and the coarse salt MVR crystallizer (31); A coarse salt MVR feed pump (23) is arranged between the coarse salt MVR feed tank (22) and the coarse salt MVR crystallizer (31).

3. The MVR evaporation system of claim 1, wherein, The fine salt MVR separator (44) is composed of a fine salt MVR crystallizer (45) on the top and a fine salt MVR crystallization leg (46) located directly below; A fine salt MVR discharge circulating pump (40) is arranged between the fine salt MVR crystallizer (45) and the fine salt MVR crystallization leg (46); The refined salt MVR crystallizer (45) is connected with the top end and the bottom of the refined salt MVR heater (43) respectively, wherein the refined salt MVR heater (43) bottom is provided with a refined salt MVR forced circulation pump (39) between the refined salt MVR heater (43) bottom and the refined salt MVR crystallizer (45), and the refined salt MVR heater (43) lower part is connected with the refined salt MVR condensate negative pressure pump (38); The refined salt MVR crystallizer (45) is connected with the refined salt MVR cyclone separator (47) and the refined salt MVR cyclone separator demisting device (48) respectively, wherein the refined salt MVR cyclone separator demisting device (48) is communicated with the refined salt MVR cyclone separator (47) located directly below, and the refined salt MVR cyclone separator demisting device (48) is provided with the refined salt MVR steam compressor (41) between the refined salt MVR cyclone separator demisting device (48) and the refined salt MVR crystallizer (45); The coarse salt dissolving tank (35) is provided with a coarse salt dissolving tank liquid level meter (4E) on the side and a third variable frequency stirrer (13C) on the top; The refined salt MVR feed tank (36) is provided with a refined salt MVR feed tank liquid level meter (4F) on the side, and the refined salt MVR feed tank (36) is provided with a refined salt MVR feed pump (37) between the refined salt MVR feed tank (36) and the refined salt MVR crystallizer (45).

4. A method for synergistically resourceful treatment of preserved szechuan pickle wastewater, characterized in that, The method is carried out by using the system of any one of claims 1-3, and specifically comprises the following steps: (1) In the advanced oxidation-Fenton pretreatment system (I), the HCl solution in the HCl storage tank (1B) and the raw material storage pool (3) are mixed in the pipeline mixer (6), the pH is adjusted to 3-4 through the first pH meter (7A), and then the mixture is introduced into the bottom of the Fenton reaction tank (11), and the Fenton reaction is carried out with H2O2 introduced into the bottom of the Fenton reaction tank (11) from the H2O2 storage tank (1A) and FeCl2 introduced into the bottom of the Fenton reaction tank (11) from the FeCl2 storage tank (1C), after the reaction is completed, the mixture is introduced into the bottom of the neutralization tank (14), and the neutralization reaction is carried out with NaOH solution introduced into the bottom of the neutralization tank (14) from the NaOH storage tank (1D), the third pH meter (7C) arranged in the neutralization tank (14) adjusts the pH in the reaction process, after the reaction is completed, the liquid is overflowed from the neutralization tank outlet (18) at the upper part of the neutralization tank (14) to the horizontal screw centrifuge (19) to realize solid-liquid separation, the solid is discharged from the solid outlet (21), and the liquid is introduced into the coarse salt MVR feed tank (22) of the coarse salt MVR evaporation crystallization system (II) through the clear liquid outlet (20); (2) In the coarse salt MVR evaporation crystallization system (II), the coarse salt in the coarse salt MVR feed tank (22) is pumped into the coarse salt MVR crystallizer (31) of the coarse salt MVR separator (30) to carry out evaporation crystallization, and the solid is separated from the coarse salt MVR crystallization leg (32) below and introduced into the coarse salt MVR discharge circulating pump (26), the liquid part is introduced into the municipal wastewater treatment system connected therewith, and the solid part is introduced into the refined salt MVR evaporation crystallization system (III) coarse salt dissolving tank (35). (3) In the refined salt MVR evaporation crystallization system (III), the coarse salt is mixed and dissolved with water in the coarse salt dissolving tank (35) and then enters the refined salt MVR feed tank (36), and then enters the refined salt MVR crystallizer (45) to perform evaporation crystallization, and enters the refined salt MVR solid-liquid separation centrifuge (42) from the refined salt MVR crystallization leg (46) below, the liquid part enters the municipal sewage treatment system connected thereto, and the solid part is refined salt for recycling.

5. The method of claim 4, wherein, The HCl storage tank (1B) and the pipeline mixer (6) are provided with an HCl diaphragm pump (2B), the HCl diaphragm pump (2B) is linked with the first pH meter (7A) to adjust the pH, specifically: by setting the pH value of the first pH meter (7A) to 3.5, the HCl diaphragm pump (2B) is used for adjusting the feeding amount, so that the pH of the mixed solution is 3-4; The NaOH storage tank (1D) and the neutralization tank (14) are provided with a NaOH diaphragm pump (2E), the NaOH diaphragm pump (2E) is linked with the third pH meter (7C) to adjust the pH, specifically: by setting the pH value of the third pH meter (7C) to 7.5, the NaOH diaphragm pump (2E) is used for adjusting the feeding amount.

6. The method of claim 4, wherein, The volume ratio of coarse salt to water in the coarse salt dissolving tank (35) is 1:3-4.

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