A method and system for resource treatment of high-sulfate organic wastewater

Abstract

The present application discloses a method and system for resource treatment of high-sulfate organic wastewater, relating to the technical field of wastewater treatment. The method includes the following steps: performing bipolar membrane separation treatment on the high-sulfate organic wastewater to obtain dilute alkali, dilute acid and dilute brine; performing evaporation and concentration treatment on the dilute alkali to obtain liquid alkali and condensed water; performing electrocatalytic oxidation treatment on the dilute brine to obtain electrocatalytic oxidation product water; performing DTRO concentration on the electrocatalytic oxidation product water to obtain DTRO product water and DTRO concentrated water; performing photoelectrolysis treatment on the dilute acid and the DTRO concentrated water to obtain hydrogen and anolyte; performing crystallization separation on the anolyte to obtain mirabilite and sodium persulfate products; using the DTRO product water to perform crystal dissolution treatment on the mirabilite to obtain a saturated or nearly saturated sodium sulfate solution and returning it to the photoelectrolysis step for cyclic treatment. The present application converts the sulfate in the wastewater into high-value sodium persulfate, avoiding the problem that a large amount of industrial by-product sodium sulfate is difficult to dispose of. At the same time, liquid alkali, dilute acid, product water, condensed water and hydrogen can also be obtained and all can be recycled, realizing the resource utilization of high-sulfate wastewater.

Description

Technical Field

[0001] The present application relates to the technical field of wastewater treatment, and particularly relates to a method and system for resource treatment of high-sulfate organic wastewater. Background Art

[0002] In the process of zero-discharge treatment of coal chemical industry brine, generally, nanofiltration is used to separate salts and then evaporation crystallization is carried out to obtain sodium sulfate and sodium chloride products, and finally zero-discharge is achieved. However, in the actual operation process, the sulfate and organic matter in the concentrated water produced by nanofiltration are both relatively high, belonging to high-sulfate organic wastewater. The content of sulfate ions in this wastewater can be as high as 80,000 - 120,000 mg / L, and the COD content is usually as high as about 300 - 2,000 mg / L. It is a typical high-concentration and difficult-to-degrade organic wastewater. At present, the process of "advanced oxidation + evaporation crystallization" is mainly used for treatment. However, in the case of high salt (total dissolved solids ≥ 50,000 mg / L), anions in the water (such as Cl - , SO4 2- , HCO 3- etc.) are prone to quenching reactions with the hydroxyl radicals generated in the catalytic oxidation process, resulting in a significant decrease in the oxidation treatment efficiency. The COD removal rate is generally only about 20 - 40%, and the organic matter concentration in the oxidized effluent is still relatively high, which in turn affects the quality of the final by-product salt. Generally, it is difficult to meet the standard requirements of Class II Grade A of "Industrial Anhydrous Sodium Sulfate" (GB / T 6009 - 2014). Even if it can meet the requirements of this standard, its recovery rate is low, the amount of miscellaneous salts is large, that is, the amount of hazardous waste is large, and the treatment cost is high. Based on this, the present application proposes a method and system for resource treatment of high-sulfate organic wastewater. Summary of the Invention

[0003] The main purpose of the present application is to provide a method and system for resource treatment of high-sulfate organic wastewater, aiming to solve the technical problem that it is difficult to treat and recycle high-sulfate organic wastewater by the existing methods.

[0004] To achieve the above purpose, the present application proposes a method for resource treatment of high-sulfate organic wastewater, including the following steps:

[0005] Perform bipolar membrane separation treatment on the high-sulfate organic wastewater to obtain dilute alkali, dilute acid, and dilute brine;

[0006] Perform evaporation and concentration treatment on the dilute alkali to recover liquid alkali and condensed water;

[0007] Perform electrocatalytic oxidation treatment on the dilute brine to obtain electrocatalytic oxidation effluent;

[0008] Perform DTRO concentration on the electrocatalytic oxidation effluent to obtain DTRO effluent and DTRO concentrated water;

[0009] Perform photoelectrolysis treatment on the dilute acid and the DTRO concentrated water to obtain hydrogen gas and anolyte;

[0010] Perform crystallization separation on the anolyte to obtain mirabilite and sodium persulfate products;

[0011] Use the DTRO-produced water to perform crystal dissolution treatment on the mirabilite to obtain a saturated or nearly saturated sodium sulfate solution and return it to the photoelectrolysis treatment step for cyclic treatment.

[0012] Optionally, the step of performing bipolar membrane separation treatment on the high-sulfate organic wastewater to obtain dilute alkali, dilute acid, and dilute brine includes:

[0013] Perform bipolar membrane separation treatment on the high-sulfate organic wastewater through a bipolar membrane reactor with an average current density of 400 - 1000 A / m 2 to obtain dilute alkali, dilute acid, and dilute brine;

[0014] Among them, the concentration of the dilute alkali is 1 - 2 mol / L, the concentration of the dilute acid is 1 - 2 mol / L, the TDS concentration in the dilute brine is 20000 - 40000 mg / L, and the COD concentration is 300 - 2000 mg / L;

[0015] The volume ratio of the salt chamber, alkali chamber, and acid chamber in the bipolar membrane reactor is (10.5 - 11.5):(7.5 - 8.5):(6.0 - 7.5).

[0016] Optionally, in the step of performing evaporation and concentration treatment on the dilute alkali to recover liquid alkali and condensed water, the evaporation operating temperature is 60 - 100 °C, the recovered liquid alkali has an effective concentration of 20 - 30%, and the steam consumption is 0.4 - 0.6 t / t (dilute alkali).

[0017] Optionally, in the step of performing electrocatalytic oxidation treatment on the dilute brine to obtain electrocatalytic oxidation-produced water, the anode uses one of a titanium suboxide ceramic electrode, a diamond electrode, or a titanium-platinum composite electrode, the cathode uses a titanium electrode or a stainless steel electrode, the current density is 300 - 600 A / m 2 , the voltage is 3 - 12 V, the residence time of the electrocatalytic oxidation reaction is 10 - 60 min, and the COD of the electrocatalytic oxidation-produced water is below 100 mg / L.

[0018] Optionally, the step of performing photoelectrolysis treatment on the dilute acid and the DTRO concentrated water to obtain hydrogen gas and anolyte includes:

[0019] Fifty to eighty percent by volume of the dilute acid is fed into a photoelectrolysis reactor together with the DTRO concentrated water for photoelectrolysis, and the remaining part of the dilute acid is subjected to resource recovery. The operating temperature of the photoelectrolysis reactor is 15 - 55°C. An acid-base regulator is added to the photoelectrolysis reactor, and the operating pH of the cathode chamber is controlled to be ≤3, while the operating pH of the anode chamber is 6 - 8. The dilute acid is in the cathode chamber, and the DTRO concentrated water is in the anode chamber. Ultraviolet light irradiation is carried out simultaneously in the anode chamber. Hydrogen is obtained from the cathode chamber, and an anolyte mixture of sodium persulfate and sodium sulfate is obtained from the anode chamber.

[0020] A diaphragm is provided in the photoelectrolysis reactor. The composition of the diaphragm is a composite ceramic material of barium titanate and clay, and the mass ratio of barium titanate to clay is 1:(3.5 - 8.8). The anode of the photoelectrolysis reactor is made of one of titanium suboxide electrodes, diamond electrodes, or titanium-platinum electrodes with a high oxygen evolution potential. The cathode of the photoelectrolysis reactor is a composite electrode with a titanium substrate and a surface coated with zirconium, tantalum, and ruthenium, and the mass ratio of titanium, zirconium, tantalum, and ruthenium is (70 - 90):(2 - 3):(0.2 - 0.5):(0.2 - 0.5). The hydrogen evolution potential of the cathode of the photoelectrolysis reactor is lower than -0.5V. The wavelength of the ultraviolet light is 185 - 365nm, and the intensity of the ultraviolet light is 200 - 500W / m 2 .

[0021] Optionally, in the step of crystallizing and separating the anolyte to obtain mirabilite and sodium persulfate products, the operating temperature of the crystallization separation is -8 to 8°C, and the content of the sodium persulfate product generated by the crystallization separation is 250 - 350g / L.

[0022] Optionally, the step of using the DTRO produced water to dissolve the mirabilite includes:

[0023] Using the DTRO produced water to dissolve the mirabilite. After the mirabilite is dissolved, a saturated or nearly saturated sodium sulfate solution is formed. The mass ratio of the DTRO produced water to the mirabilite is (0.2 - 0.3):1. The dissolution temperature is controlled at 35 - 55°C, the residence time for dissolution is 0.5 - 5min, and stirring is carried out simultaneously at a stirring speed of 30 - 120r / min.

[0024] The present application also provides a resource treatment system for high-sulfate organic wastewater, which includes a bipolar membrane reactor, an electrocatalytic oxidation reactor, a DTRO membrane device, a photoelectrolysis reactor, a crystallization separation device, a crystal dissolution reactor, and an evaporator. The dilute alkali output end of the bipolar membrane reactor is connected to the evaporator, the dilute brine output end of the bipolar membrane reactor is connected to the electrocatalytic oxidation reactor, the water production end of the electrocatalytic oxidation reactor is connected to the DTRO membrane device, the dilute acid output end of the bipolar membrane reactor and the concentrated water end of the DTRO membrane device are connected to the water inlet end of the photoelectrolysis reactor. A hydrogen outlet end is provided on the cathode side of the photoelectrolysis reactor, the anode side of the photoelectrolysis reactor is connected to the crystallization separation device, the water production ends of the crystallization separation device and the DTRO membrane device are both connected to the crystal dissolution reactor, and the crystal dissolution reactor is connected to the water inlet end of the photoelectrolysis reactor.

[0025] Optionally, the photoelectrolysis reactor is provided with electrode plates and diaphragms. The electrode plates include an anode mesh plate and a cathode mesh plate. The anode mesh plates and the cathode mesh plates are arranged alternately in parallel. There are n anode mesh plates and n + 1 cathode mesh plates. The diaphragms are located between the anode mesh plates and the cathode mesh plates, and there are 2n diaphragms. The electrode plates are evenly provided with water passing holes. Ultraviolet lamps are provided at both the bottom and the top of the photoelectrolysis reactor, and the ultraviolet lamps are perpendicularly distributed with respect to the electrode plates.

[0026] Optionally, the crystallization separation device includes a freezing reactor, a compressor, a condenser, and a centrifuge. The photoelectrolysis reactor is connected to the water inlet end of the freezing reactor. A heat exchanger is provided in the freezing reactor. The condenser, the heat exchanger, and the compressor are connected in sequence, and the compressor is connected to the condenser. The outlet end of the freezing reactor is connected to the centrifuge. A centrifugal feed pump is provided between the freezing reactor and the centrifuge. The solid outlet end of the centrifuge is connected to the crystal dissolution reactor.

[0027] The present application has at least the following beneficial effects:

[0028] In this application, high-sulfate organic wastewater is first subjected to bipolar membrane separation to obtain dilute alkali, dilute acid, and dilute brine respectively. The dilute alkali is evaporated and concentrated to obtain liquid alkali, which can be recycled and utilized, and the generated condensate water can be reused. After the dilute brine undergoes bipolar membrane separation, its sulfate content is significantly reduced, and the TDS can be reduced to below 50,000 mg / L. At this time, electrocatalytic oxidation is carried out on the dilute brine. Since the anion concentration in the water is relatively low, the quenching reaction of hydroxyl radicals will be significantly weakened, and the corresponding oxidation efficiency will be greatly improved, making the oxidation of organic matter more complete. Compared with the existing technology of directly oxidizing high-sulfate wastewater and then evaporating it, the oxidation efficiency of this application can be increased by more than 40-50%, so that the quality of the final salt product is not affected by organic matter. Then, by subjecting the electrocatalytic oxidation product water to DTRO concentration, salt water resources can be further recovered. Next, photoelectrolysis reaction is carried out on sodium sulfate and dilute acid in the DTRO concentrated water. Sodium sulfate discharges at the anode to generate sodium persulfate, and sulfuric acid obtains electrons at the cathode to generate hydrogen. A mixed solution of sodium persulfate and sodium sulfate is obtained on the anode side. Then, the remaining sodium sulfate is crystallized and separated to obtain a sodium persulfate solution with a concentration of 250-350 g / L, and by-product mirabilite (sodium sulfate decahydrate) is obtained at the same time. To avoid the problem of unsalable mirabilite produced, this application further performs dissolution and crystallization treatment on mirabilite, and directly uses a part of the DTRO product water for supplementation. After forming a saturated or nearly saturated sodium sulfate solution, photoelectrolysis treatment is carried out again to improve the recovery rate of sodium persulfate products. By converting sulfate in the wastewater into high-value sodium persulfate, this application not only avoids the problem that a large amount of industrial by-product sodium sulfate generated during evaporation after oxidation in the existing zero-discharge process for coal chemical industry concentrated brine is difficult to dispose of, but also the recovered sodium persulfate has a high added value, which can offset a part of the treatment cost of high-sulfate wastewater, with considerable economic benefits. Moreover, in addition to obtaining sodium persulfate, liquid alkali, dilute acid, product water, condensate water, and hydrogen can also be obtained, all of which can be recycled and utilized, thus realizing the resource utilization of high-sulfate wastewater.

[0029] The system of the present application includes a bipolar membrane reactor, an electrocatalytic oxidation reactor, a DTRO membrane device, a photoelectrolysis reactor, a crystallization separation device, a crystal dissolution reactor and an evaporator. The high-sulfate organic wastewater first enters the bipolar membrane reactor for bipolar membrane separation to achieve the resource recovery of acids and bases. The dilute alkali output end of the bipolar membrane reactor is connected to the evaporator, and liquid alkali is obtained after concentration by the evaporator, so that liquid alkali is recovered. At the same time, the dilute brine generated by the bipolar membrane reactor oxidizes and removes organic substances through the electrocatalytic oxidation reactor, and the produced water is concentrated by the DTRO membrane device. Part of the DTRO-produced water meets the standards for reuse, and the other part of the produced water is used for the dissolution of mirabilite crystals. The DTRO concentrated water and the dilute acid generated by the bipolar membrane reactor are electrolyzed through the photoelectrolysis reactor to generate a mixed solution containing sodium persulfate and hydrogen. The mixed solution is separated by the crystallization separation device to obtain sodium persulfate. At the same time, the by-product sodium sulfate decahydrate separated out is washed and dissolved through the crystal dissolution reactor to obtain a saturated or nearly saturated sodium sulfate solution, and the sodium sulfate is returned to the photoelectrolysis reactor for cyclic treatment. Through the treatment of the high-sulfate organic wastewater by this system, high-value sodium persulfate and liquid alkali can be recovered, realizing resource utilization. Description of the Drawings

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application 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 drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on the structures shown in these drawings without creative efforts.

[0031] Figure 1 It is a schematic flow chart of the method for resource treatment of high-sulfate organic wastewater described in the embodiment of the present application;

[0032] Figure 2 It is a schematic structural diagram of the high-sulfate organic wastewater resource treatment system described in the embodiment of the present application;

[0033] Figure 3 It is a front view of the photoelectrolysis reactor described in the embodiment of the present application;

[0034] Figure 4 It is a top view of the photoelectrolysis reactor described in the embodiment of the present application;

[0035] Figure 5 It is a left view of the photoelectrolysis reactor described in the embodiment of the present application.

[0036] Reference Signs:

[0037] 1 - Bipolar membrane reactor; 101 - Anion membrane; 102 - Cation membrane; 103 - Bipolar membrane; 2 - Electro - catalytic oxidation reactor; 201 - Effluent area; 3 - Water tank; 4 - DTRO membrane device; 5 - Photo - electrolysis reactor; 501 - Ultraviolet lamp; 502 - Electrode plate; 503 - Water - passing hole; 504 - Anode mesh plate; 505 - Cathode mesh plate; 506 - Diaphragm; 6 - Crystallization separation device; 601 - Heat exchanger; 602 - Freezing reactor; 603 - Compressor; 604 - Condenser; 605 - Centrifugal feed pump; 606 - Centrifuge; 7 - Crystal dissolution reactor; 701 - Heating pipe; 702 - Agitator; 8 - Evaporator; 9 - Feed water pump; 10 - Booster pump; 11 - Hot solution transfer pump.

[0038] The realization of the purpose of this application, functional characteristics and advantages will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of this application will be clearly and completely described with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of this application.

[0040] Industrial sodium persulfate can be used as bleaching agent, oxidant, textile desizing agent, sulfur - containing dye color - developing agent, breaker of oil - well fracturing fluid, initiator for organic polymer emulsion polymerization, waste - liquid treatment agent, metal surface treatment agent, and etchant for printed circuit boards, etc. At present, the market price of sodium persulfate is 5000 - 6000 yuan / ton, with a relatively high value. If the high - sulfate in wastewater can be converted into sodium persulfate, it can not only solve the environmental protection problem, but also bring significant economic benefits.

[0041] In view of the above - mentioned technical problems existing in the prior art, the embodiments of this application provide a method for resource treatment of high - sulfate organic wastewater, as Figure 1 shown, including the following steps:

[0042] Perform bipolar membrane separation treatment on the high - sulfate organic wastewater to obtain dilute alkali, dilute acid and dilute brine;

[0043] Perform evaporation and concentration treatment on the dilute alkali to recover liquid alkali and condensed water;

[0044] Perform electro - catalytic oxidation treatment on the dilute brine to obtain electro - catalytic oxidation product water;

[0045] Perform DTRO concentration on the electro - catalytic oxidation product water to obtain DTRO product water and DTRO concentrated water;

[0046] The dilute acid and the DTRO concentrated water are subjected to photoelectrolysis treatment to obtain hydrogen and anolyte;

[0047] The anolyte is subjected to crystallization separation to obtain mirabilite and sodium persulfate products;

[0048] The mirabilite is subjected to crystal dissolution treatment with the DTRO-produced water to obtain a saturated or nearly saturated sodium sulfate solution, which is returned to the photoelectrolysis treatment step for cyclic treatment.

[0049] In this application, the high-sulfate organic wastewater is first subjected to bipolar membrane separation to obtain dilute alkali, dilute acid and dilute brine respectively. The dilute alkali is evaporated and concentrated to obtain liquid alkali, which can be recycled, and the generated condensed water can be reused. After the dilute brine is subjected to bipolar membrane separation, its sulfate content is greatly reduced, and the TDS can be reduced to less than 50000 mg / L. At this time, the dilute brine is subjected to electrocatalytic oxidation. Since the anion concentration in the water is relatively low, the quenching reaction of hydroxyl radicals will be significantly weakened, and the corresponding oxidation efficiency will be greatly improved, making the oxidation of organic matter more thorough. Compared with the existing technology of directly oxidizing and evaporating high-sulfate wastewater, the oxidation efficiency of this application can be increased by more than 40-50%, so that the quality of the final salt product is not affected by organic matter. Then, by subjecting the electrocatalytic oxidation-produced water to DTRO concentration, salt water resources can be further recovered. Then, the sodium sulfate and dilute acid in the DTRO concentrated water are subjected to a photoelectrolysis reaction. Sodium sulfate discharges at the anode to generate sodium persulfate, and sulfuric acid reacts at the cathode to obtain electrons and generate hydrogen. A mixed solution of sodium persulfate and sodium sulfate is obtained on the anode side. Then, the residual sodium sulfate is subjected to crystallization separation to obtain a sodium persulfate solution, and at the same time, by-product mirabilite (sodium sulfate decahydrate) is obtained. To avoid the problem that the produced mirabilite has no market, this application further performs crystal dissolution treatment on the mirabilite and directly uses a part of the DTRO-produced water for supplementation. After forming a saturated or nearly saturated sodium sulfate solution, it is then subjected to photoelectrolysis treatment to improve the recovery rate of sodium persulfate products. By converting the sulfate in the wastewater into high-value sodium persulfate, this application not only avoids the problem that a large amount of industrial by-product sodium sulfate generated by oxidation and evaporation in the existing zero-discharge process of coal chemical industry concentrated brine is difficult to dispose of, but also the recovered sodium persulfate has a high added value, which can offset part of the treatment cost of high-sulfate wastewater, and the economic benefit is considerable. In addition to obtaining sodium persulfate, liquid alkali, produced water, condensed water and hydrogen can also be obtained, all of which can be recycled, thus realizing the resource utilization of high-sulfate wastewater.

[0050] As an implementable mode of this application, the step of subjecting the high-sulfate organic wastewater to bipolar membrane separation treatment to obtain dilute alkali, dilute acid and dilute brine includes:

[0051] The high-sulfate organic wastewater is subjected to bipolar membrane separation treatment through a bipolar membrane reactor, with an average current density of 400-1000 A / m 2, dilute alkali, dilute acid and dilute brine are obtained;

[0052] Among them, the concentration of the dilute alkali is 1 - 2 mol / L, the concentration of the dilute acid is 1 - 2 mol / L, the TDS concentration in the dilute brine is 20000 - 40000 mg / L, and the COD concentration is 300 - 2000 mg / L;

[0053] The volume ratio of the salt chamber, alkali chamber and acid chamber in the bipolar membrane reactor is (10.5 - 11.5):(7.5 - 8.5):(6.0 - 7.5).

[0054] Converting high - sulfate organic wastewater into dilute brine through a bipolar membrane reactor can greatly reduce the content of sulfate, and reduce the TDS to below 50000 mg / L, facilitating subsequent electro - catalytic oxidation of the dilute brine, thereby greatly improving the oxidation efficiency, and at the same time, the recovery of acid and alkali can be realized.

[0055] As an implementable mode of this application, in the step of evaporating and concentrating the dilute alkali to recover liquid alkali and condensed water, the evaporation operating temperature is 60 - 100 °C, the recovered liquid alkali has an effective concentration of 20 - 30%, and the steam consumption is 0.4 - 0.6 t / t (dilute alkali).

[0056] As an implementable mode of this application, in the step of electro - catalytically oxidizing the dilute brine to obtain electro - catalytic oxidation product water, the anode uses one of titanium sub - oxide ceramic electrode, diamond electrode or titanium - platinum composite electrode, the cathode uses a titanium electrode or a stainless - steel electrode, the current density is 300 - 600 A / m 2 , the voltage is 3 - 12 V, the residence time of the electro - catalytic oxidation reaction is 10 - 60 min, and the COD of the electro - catalytic oxidation product water is below 100 mg / L.

[0057] Specifically, the anode uses a titanium sub - oxide ceramic electrode, a diamond electrode or a titanium - platinum composite electrode, which can efficiently remove organic matter and ammonia nitrogen. The cathode uses a titanium electrode or a stainless - steel electrode, which has good corrosion resistance. During the electro - catalytic oxidation process, under the action of an externally applied strong current, a potential difference is formed between the anode and the cathode, which can promote the migration or transfer of ions in the solution in the electrolyte, form a strong electrochemical reaction, convert water into hydroxyl radicals and oxidize organic matter, and at the same time convert Cl - into ClO - , HClO and other substances to oxidize ammonia nitrogen, thereby greatly reducing the organic matter and ammonia nitrogen in the dilute brine.

[0058] As an implementable embodiment of the present application, in the step of subjecting the electrocatalytic oxidation-produced water to DTRO concentration to obtain DTRO-produced water and DTRO-concentrated water, a seawater desalination membrane is used for DTRO concentration, the operating pressure is 40-90 bar, and the recovery rate is 70-85%.

[0059] Specifically, the DTRO (disc tube reverse osmosis) technology is a membrane separation technology that uses the selective permeability of the membrane to separate water molecules from the solution. It is mainly based on the selective permeability of the semi-permeable membrane. Under high-pressure drive, water molecules can pass through the semi-permeable membrane into the membrane, while the solute is retained outside the membrane. The seawater desalination membrane has high desalination rate, anti-pollution property, corrosion resistance and high efficiency and stability. After subjecting the electrocatalytic oxidation-produced water to DTRO concentration, it can effectively improve the recovery rate of salts in the electrocatalytic oxidation-produced water, has strong anti-pollution ability, the system runs more stably, and has good economic benefits.

[0060] As an implementable embodiment of the present application, the step of subjecting the dilute acid and the DTRO-concentrated water to photoelectrolysis treatment to obtain hydrogen and anolyte includes:

[0061] Part of the dilute acid with a volume ratio of 50-80% and the DTRO-concentrated water are fed into a photoelectrolysis reactor for photoelectrolysis together, and the remaining part of the dilute acid is subjected to resource recovery. The operating temperature of the photoelectrolysis reactor is 15-55 °C. An acid-base regulator is added to the photoelectrolysis reactor, and the pH of the cathode chamber is controlled to be ≤ 3, and the pH of the anode chamber is 6-8. The dilute acid is in the cathode chamber, and the DTRO-concentrated water is in the anode chamber. Ultraviolet light irradiation is carried out in the anode chamber at the same time; hydrogen is obtained from the cathode chamber, and an anolyte mixed with sodium persulfate and sodium sulfate is obtained from the anode chamber;

[0062] A diaphragm is provided in the photoelectrolysis reactor, and the composition of the diaphragm is a composite ceramic material of barium titanate and clay, and the mass ratio of barium titanate to clay is 1:(3.5-8.8); the anode of the photoelectrolysis reactor is made of one of titanium suboxide electrodes, diamond electrodes or titanium-platinum electrodes with a high oxygen evolution potential; the cathode of the photoelectrolysis reactor is a composite electrode with titanium as the substrate and zirconium, tantalum, and ruthenium plated on the surface, and the mass ratio of titanium, zirconium, tantalum, and ruthenium is (70-90):(2-3):(0.2-0.5):(0.2-0.5), and the hydrogen evolution potential of the cathode of the photoelectrolysis reactor is lower than -0.5 V; the wavelength of the ultraviolet light is 185-365 nm, and the intensity of the ultraviolet light is 200-500 W / m 2 .

[0063] Due to the low current efficiency of the existing technology for producing Na2S2O8 by electrolyzing Na2SO4, the efficiency of producing Na2S2O8 is low, and in the electrolysis system of Na2S2O8—Na2SO4—H2SO4—H2O, the solubility difference between Na2S2O8 and Na2SO4 is small, making it very difficult to extract Na2S2O8 from the electrolyte. Therefore, in this application, anodic electrodes such as titanium suboxide, diamond electrodes, or titanium-platinum electrodes with high oxygen evolution potential are used to inhibit the generation of anodic by-product oxygen, so that the main reaction at the anode is the conversion of SO4 2- to S2O8 2- At the same time, by irradiating with ultraviolet light, the electrolytic conversion of SO4 2- to persulfate is promoted, the production efficiency of persulfate is improved, and by setting a diaphragm in the photoelectrolysis reactor, the diaphragm allows hydrogen to pass through while blocking the passage of ions in water, preventing the S2O8 2- generated at the anode from migrating to the cathode and being reduced and consumed. Thus, a mixed solution of Na2S2O8 and Na2SO4 is obtained on the anode side. After freezing crystallization and precipitation of mirabilite Na2SO4·10H2O, high-purity sodium persulfate is obtained; while the cathode uses a composite metal material with titanium as the substrate and zirconium, tantalum, and ruthenium plated on the surface, and the hydrogen evolution potential is lower than -0.5V, which can effectively promote the generation of hydrogen and avoid cathode corrosion.

[0064] Specifically, Na2SO4 discharges at the anode to generate Na2S2O8, and H2SO4 reacts at the cathode to obtain electrons and generate H2. The reaction equations are as follows:

[0065] Anodic reaction: 2SO4 2- →S2O8 2- +2e - ;

[0066] Cathodic reaction: 2H + +2e - →H2↑.

[0067] As an implementable mode of this application, in the step of crystallizing and separating the anolyte to obtain mirabilite and sodium persulfate products, the operating temperature of the crystallization separation is -8 to 8°C, and the content of the sodium persulfate product generated by the crystallization separation is 250 - 350 g / L.

[0068] Specifically, the crystallization separation utilizes the principle that the solubility of sodium sulfate drops sharply under low-temperature conditions, and a large amount of mirabilite precipitates from water. At this time, sodium persulfate is not greatly affected by the temperature drop and will continue to exist in water in a dissolved state, thus separating sodium persulfate and sodium sulfate. Sodium persulfate has high economic value and can be used as a raw material for preparing industrial sodium persulfate for resource utilization. After the mirabilite is dissolved and recrystallized, it returns to the system to continue photoelectrolysis to produce sodium persulfate, thereby improving the recovery rate of sodium persulfate.

[0069] As an implementable mode of the present application, the step of using the DTRO produced water to perform crystal dissolution treatment on the mirabilite includes:

[0070] Using the DTRO produced water to dissolve the mirabilite. After the mirabilite is dissolved, a saturated or nearly saturated sodium sulfate solution is formed. The mass ratio of the DTRO produced water to the mirabilite is (0.2 - 0.3):1. The crystal dissolution temperature is controlled at 35 - 55°C, the crystal dissolution residence time is 0.5 - 5 min, and stirring is carried out simultaneously, with the stirring speed being 30 - 120 r / min.

[0071] Specifically, the mirabilite produced by crystallization needs to be dissolved to form a saturated or nearly saturated sodium sulfate solution, and finally returned to the photoelectrolysis step for cyclic treatment to avoid the problem that the finally produced mirabilite has no market, and can improve the recovery rate of the sodium persulfate product. Since water needs to be added to dissolve the mirabilite during the crystal dissolution process, this part of the externally added water can be directly supplemented with the DTRO produced water, thereby realizing the internal cyclic utilization of the DTRO produced water in the system.

[0072] The embodiment of the present application also provides a resource treatment system for high-sulfate organic wastewater, including a bipolar membrane reactor 1, an electrocatalytic oxidation reactor 2, a DTRO membrane device 4, a photoelectrolysis reactor 5, a crystallization separation device 6, a crystal dissolution reactor 7, and an evaporator 8. The dilute alkali output end of the bipolar membrane reactor 1 is connected to the evaporator 8, the dilute brine output end of the bipolar membrane reactor 1 is connected to the electrocatalytic oxidation reactor 2, the water production end of the electrocatalytic oxidation reactor 2 is connected to the DTRO membrane device 4, the dilute acid output end of the bipolar membrane reactor 1 and the concentrated water end of the DTRO membrane device 4 are connected to the water inlet end of the photoelectrolysis reactor 5. A hydrogen outlet end is provided on the cathode side of the photoelectrolysis reactor 5. The anode side of the photoelectrolysis reactor 5 is connected to the crystallization separation device 6. The water production ends of the crystallization separation device 6 and the DTRO membrane device 4 are both connected to the crystal dissolution reactor 7, and the crystal dissolution reactor 7 is connected to the water inlet end of the photoelectrolysis reactor 5.

[0073] The resource treatment system for high-sulfate organic wastewater of the present application includes a bipolar membrane reactor 1, an electrocatalytic oxidation reactor 2, a DTRO membrane device 4, a photoelectrolysis reactor 5, a crystallization separation device 6, a crystal dissolution reactor 7, and an evaporator 8. The high-sulfate organic wastewater first enters the bipolar membrane reactor 1 for membrane separation to achieve the resource recovery of acids and alkalis. The dilute alkali output end of the bipolar membrane reactor 1 is connected to the evaporator 8, and liquid alkali is obtained after concentration by the evaporator 8, thereby recovering liquid alkali. At the same time, the dilute brine generated by the bipolar membrane reactor 1 oxidizes and removes organic matter through the electrocatalytic oxidation reactor 2. The produced water is further concentrated by the DTRO membrane device 4. A part of the DTRO-produced water meets the standards and is recycled, and the other part of the produced water is used for the crystal dissolution of mirabilite. The DTRO concentrated water and the dilute acid generated by the bipolar membrane reactor 1 are electrolyzed through the photoelectrolysis reactor 5 to generate a mixed solution containing sodium persulfate and hydrogen. After separation by the crystallization separation device 6, sodium persulfate is obtained. At the same time, the by-product sodium sulfate decahydrate separated out is washed and dissolved through the crystal dissolution reactor 7 to obtain a saturated or nearly saturated sodium sulfate solution, and the sodium sulfate returns to the photoelectrolysis reactor 5 for cyclic treatment. Through the treatment of high-sulfate organic wastewater by this system, high-value sodium persulfate and liquid alkali can be recovered, realizing resource utilization.

[0074] As an implementable mode of the present application, the bipolar membrane reactor 1 includes a cathode membrane 101, an anode membrane 102, and at least one group of bipolar membranes 103. The cathode membrane 101, the anode membrane 102, and the bipolar membranes 103 are connected by a positioning flexible connection method, and the cathode membrane 101 and the anode membrane 102 adopt homogeneous membranes.

[0075] As an implementable mode of the present application, a water outlet area 201 is provided inside the electrocatalytic oxidation reactor 2, and a water tank 3 is provided between the electrocatalytic oxidation reactor 2 and the DTRO membrane device 4. The water outlet area 201 is connected to the water tank 3, and the produced water treated by the electrocatalytic oxidation reactor 2 enters the water tank 3 for storage through the water outlet area 201.

[0076] As an implementable mode of the present application, a tubular electrode or a plate electrode is provided in the reaction area of the electrocatalytic oxidation reactor 2. The tubular electrode is a hollow cylindrical electrode assembly with the same axis for the cathode and anode, and the plate electrode is a parallel plate electrode with an alternating arrangement of the cathode and anode.

[0077] As an implementable mode of the present application, the photoelectrolysis reactor 5 is provided with an electrode plate 502 and a diaphragm 506. The electrode plate 502 includes an anode mesh plate 504 and a cathode mesh plate 505. The anode mesh plate 504 and the cathode mesh plate 505 are arranged in parallel and alternately. There are n anode mesh plates 504 and n + 1 cathode mesh plates 505. The diaphragm 506 is located between the anode mesh plate 504 and the cathode mesh plate 505, and there are 2n diaphragms 506. The electrode plate 502 is uniformly provided with water passing holes 503. Ultraviolet lamps are provided at both the bottom and the top of the photoelectrolysis reactor 5, and the ultraviolet lamp 501 is vertically distributed with respect to the electrode plate 502.

[0078] Specifically, the aperture of the water passing hole 503 is 2 - 4 mm, and the porosity is 20 - 30%, which facilitates smooth water flow and improves the mass transfer efficiency. The central distance between the bottom ultraviolet lamp 501 and the top ultraviolet lamp 501 is 300 - 800 mm. The ultraviolet lamp 501 is a multi-group tubular lamp arranged in parallel, and a waterproof quartz glass sleeve is provided outside the lamp tube.

[0079] As an implementable mode of the present application, the crystallization separation device 6 includes a freezing reactor 602, a compressor 603, a condenser 604 and a centrifuge 606. The photoelectrolysis reactor 5 is connected to the water inlet end of the freezing reactor 602. A heat exchanger 601 is provided in the freezing reactor 602. The condenser 604, the heat exchanger 601 and the compressor 603 are connected in sequence, the compressor 603 is connected to the condenser 604, the outlet end of the freezing reactor 602 is connected to the centrifuge 606, a centrifugal feed pump 606 is provided between the freezing reactor 602 and the centrifuge 606, and the solid outlet end of the centrifuge 606 is connected to the crystal dissolution reactor 7.

[0080] Specifically, in the crystallization separation process, after the anolyte is heat-exchanged by the heat exchanger 601, it is compressed by the compressor 603 and condensed by the condenser 604 in sequence, and the temperature is reduced to between -8 and 8 °C, so that sodium sulfate in the anolyte crystallizes out to obtain mirabilite, and then the mirabilite is separated by the centrifuge 606. The separated filtrate is highly pure sodium persulfate.

[0081] As an implementable mode of the present application, a heating pipe 701 and a stirrer 702 are provided in the crystal dissolution reactor 7. To promote the rapid dissolution of mirabilite crystals into a saturated or nearly saturated sodium sulfate solution, while heating through the heating pipe 701, stirring is carried out by the stirrer 702, which can improve the dissolution rate of mirabilite.

[0082] The above technical solutions of the present application will be described in detail below in conjunction with specific embodiments.

[0083] Example 1

[0084] A resource treatment method for high-sulfate organic wastewater, comprising the following steps:

[0085] Pump the high-sulfate organic wastewater into the bipolar membrane reactor 1 through the feed water pump 9 for membrane separation treatment, with an average current density of 700 A / m 2 , to obtain dilute alkali of 1.5 mol / L, dilute acid of 1.5 mol / L and dilute brine; the TDS concentration in the dilute brine is 28342 mg / L, and the COD concentration is 1125 mg / L;

[0086] The volume ratio of the salt chamber, alkali chamber and acid chamber in the bipolar membrane reactor 1 is 11:8:6.7;

[0087] Pass the dilute alkali from the alkali chamber into the evaporator 8 for evaporation and concentration treatment. The evaporation operating temperature is 80 °C, the steam consumption is 0.5 t / t (dilute alkali), and liquid alkali with an effective concentration of 25% and condensed water are recovered. The condensed water is recycled;

[0088] Pass the dilute brine from the salt chamber into the electrocatalytic oxidation reactor 2 for electrocatalytic oxidation treatment. The anode uses a titanium suboxide ceramic electrode, the cathode uses a titanium electrode, and the current density is 450 A / m 2 , the voltage is 7 V, the residence time of the electrocatalytic oxidation reaction is 35 min, the COD of the electrocatalytic oxidation product water is 85 mg / L, and electrocatalytic oxidation product water is obtained;

[0089] Store the electrocatalytic oxidation product water in the water tank 3, and then pass it through the booster pump 10 into the DTRO membrane device 4 for DTRO concentration. Use a seawater desalination membrane for DTRO concentration, with an operating pressure of 65 bar and a recovery rate of 77%, to obtain DTRO product water and DTRO concentrated water;

[0090] Recover half of the dilute acid, and pass the other half from the acid chamber into the photoelectrolysis reactor 5, and pass the DTRO concentrated water into the photoelectrolysis reactor 5. The operating temperature of the photoelectrolysis reaction is 35 °C. Add an acid-base regulator to the photoelectrolysis reactor 5 to control the operating pH of the cathode chamber ≤ 3 and the operating pH of the anode chamber is 7.2. The dilute acid is in the cathode chamber, and the DTRO concentrated water is in the anode chamber. At the same time, perform ultraviolet light irradiation in the anode chamber for electrolysis. Hydrogen is collected from the cathode chamber, and an anolyte mixed with sodium persulfate and sodium sulfate is collected from the anode chamber;

[0091] A diaphragm 506 is provided in the photoelectrolysis reactor 5. The composition of the diaphragm 506 is a composite ceramic material of barium titanate and clay, and the mass ratio of barium titanate to clay is 1:6.3. The anode of the photoelectrolysis reactor 5 uses a titanium suboxide electrode with a high oxygen evolution potential. The cathode of the photoelectrolysis reactor 5 uses a composite electrode with a titanium substrate and a surface coated with zirconium, tantalum, and ruthenium, and the mass ratio of titanium, zirconium, tantalum, and ruthenium is 80:2.5:0.3:0.35. The hydrogen evolution potential of the cathode of the photoelectrolysis reactor 5 is lower than -0.5V.

[0092] The anolyte is introduced into the crystallization separation device 6, and the temperature is reduced to 0 °C to crystallize and separate the residual sodium sulfate, obtaining mirabilite and sodium persulfate at 300 g / L.

[0093] The mirabilite is added to the crystal dissolution reactor 7, and the mirabilite is dissolved with DTRO-produced water to form a saturated or nearly saturated sodium sulfate solution after dissolution. The mass ratio of DTRO-produced water to mirabilite is 0.25:1. The crystal dissolution temperature is controlled at 45 °C, the crystal dissolution residence time is 2.5 min, and stirring is carried out simultaneously at a stirring speed of 75 r / min. The saturated or nearly saturated sodium sulfate solution is pumped into the photoelectrolysis reactor 5 through the hot solution transfer pump 11 for circulation treatment.

[0094] Example 2

[0095] A method for the resource treatment of high-sulfate organic wastewater includes the following steps:

[0096] The high-sulfate organic wastewater is pumped into the bipolar membrane reactor 1 through the feed water pump 9 for bipolar membrane separation treatment, and its average current density is 1000 A / m 2 , obtaining 2 mol / L dilute alkali, 2 mol / L dilute acid, and dilute brine; the TDS concentration in the dilute brine is 20134 mg / L, and the COD concentration is 317 mg / L.

[0097] The volume ratio of the salt chamber, alkali chamber, and acid chamber in the bipolar membrane reactor 1 is 10.5:7.5:6.2.

[0098] The dilute alkali is introduced into the evaporator 8 from the alkali chamber for evaporation and concentration treatment. The evaporation operating temperature is 100 °C, the steam consumption is 0.4 t / t (dilute alkali), and effective concentration 20% liquid alkali and condensed water are recovered, and the condensed water is reused.

[0099] The dilute brine is introduced into the electrocatalytic oxidation reactor 2 from the salt chamber for electrocatalytic oxidation treatment. The anode uses one of a titanium suboxide ceramic electrode, a diamond electrode, or a titanium-platinum composite electrode, and the cathode uses a titanium electrode or a stainless steel electrode. The current density is 600 A / m 2, the residence time of the electrocatalytic oxidation reaction is 60 min, the COD of the water produced by electrocatalytic oxidation is 43 mg / L, and the removal rate is 86.4%. The water produced by electrocatalytic oxidation is obtained;

[0100] The water produced by electrocatalytic oxidation is stored in the water tank 3, and then passed through the booster pump 10 into the DTRO membrane device 4 for DTRO concentration. The seawater desalination membrane is used for DTRO concentration, the operating pressure is 90 bar, and the recovery rate is 85%. The DTRO produced water and DTRO concentrated water are obtained;

[0101] Part of the dilute acid is recycled, and the other part is introduced into the photoelectrolysis reactor 5 from the acid chamber, and the volume ratio of the two is 2:8. The DTRO concentrated water is introduced into the photoelectrolysis reactor 5 for photoelectrolysis. The operating temperature of the photoelectrolysis reactor 5 is 15 - 55 °C. An acid-base regulator is added to the photoelectrolysis reactor 5 to control the pH of the cathode chamber to be ≤ 3 and the pH of the anode chamber to be 8. The dilute acid is in the cathode chamber, and the DTRO concentrated water is in the anode chamber. Ultraviolet light irradiation is carried out simultaneously in the anode chamber; hydrogen is collected from the cathode chamber, and anolyte mixed with sodium persulfate and sodium sulfate is collected from the anode chamber;

[0102] A diaphragm 506 is arranged in the photoelectrolysis reactor 5. The composition of the diaphragm 506 is a composite ceramic material of barium titanate and clay, and the mass ratio of barium titanate to clay is 1:8.8; the anode of the photoelectrolysis reactor 5 uses a titanium-platinum electrode with a high oxygen evolution potential; the cathode of the photoelectrolysis reactor 5 uses a composite electrode with titanium as the substrate and zirconium, tantalum, and ruthenium plated on the surface, and the mass ratio of titanium, zirconium, tantalum, and ruthenium is 90:3:0.5:0.5. The hydrogen evolution potential of the cathode of the photoelectrolysis reactor 5 is lower than -0.5 V;

[0103] The anolyte is introduced into the crystallization separation device 6, and the temperature is reduced to -5 °C to crystallize and separate the remaining small amount of sodium sulfate, and mirabilite and 350 g / L of sodium persulfate are separated;

[0104] The mirabilite is added to the crystal dissolution reactor 7, and the mirabilite is dissolved with the DTRO produced water to form a saturated or nearly saturated sodium sulfate solution. The mass ratio of the DTRO produced water to the mirabilite is 0.3:1. The crystal dissolution temperature is controlled at 55 °C, and the residence time of crystal dissolution is 5 min. Stirring is carried out simultaneously, and the stirring speed is 120 r / min. A saturated or nearly saturated sodium sulfate solution is obtained and pumped into the photoelectrolysis reactor 5 through the hot solution transfer pump 11 for cyclic treatment.

[0105] Comparative example

[0106] Compared with Example 2, when diluting brine was introduced into the electrocatalytic oxidation reactor 2 for electrocatalytic oxidation treatment, salt (sodium sulfate) was added to increase the TDS in water from 20134 mg / L to 60000 mg / L, and the electrocatalytic oxidation reaction was carried out under the same operating conditions as in Example 2, and the remaining steps were the same. The comparison data during the electrocatalytic oxidation reaction are shown in Table 1 below.

[0107] Table 1 Experimental data of electrocatalytic oxidation reaction at different salt contents

[0108]

[0109] As can be seen from Table 1, the COD of the effluent from electrocatalytic oxidation in the comparative example was 185 mg / L, and the removal rate was only 41.6%. This shows that the higher the TDS salt content in the influent, the lower the efficiency of electrocatalytic oxidation in removing COD under the same electrocatalytic oxidation reaction conditions. It further illustrates that the higher the salt content, the greater the inhibitory effect on the catalytic oxidation reaction efficiency, that is, reducing the salt content in water can weaken the annihilation effect of hydroxyl radicals during the catalytic oxidation process.

[0110] The above are only optional embodiments of the present application, and do not limit the patent scope of the present application. Any equivalent structural transformation made by using the content of the specification and drawings of the present application under the inventive concept of the present application, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present application.

Claims

1. A method for resource treatment of high-sulfate organic wastewater, characterized in that: The following steps are involved: The high-sulfate organic wastewater is subjected to bipolar membrane separation treatment to obtain dilute alkali, dilute acid and dilute brine; The diluted alkali is evaporated and concentrated to obtain liquid alkali and condensed water; The dilute brine is subjected to electrocatalytic oxidation treatment to obtain electrocatalytic oxidation water production; wherein the anode is one of a sub-titanium oxide ceramic electrode, a diamond electrode or a titanium-platinum composite electrode, the cathode is a titanium electrode or a stainless steel electrode, and the current density is 300-600A / m 2 , the voltage is 3-12V, the residence time of the electrocatalytic oxidation reaction is 10-60min, and the COD of the electrocatalytic oxidation water is below 100mg / L; The electrocatalytic oxidation produced water is concentrated by disc-tube reverse osmosis to obtain reverse osmosis concentrated produced water and reverse osmosis concentrated concentrated water; A portion of the dilute acid accounting for 50-80% by volume is introduced into a photoelectrolysis reactor together with the reverse osmosis concentrated concentrated water for photoelectrolysis, and the remaining portion of the dilute acid is recycled. The operating temperature of the photoelectrolysis reactor is 15-55°C. An acid-base regulator is added to the photoelectrolysis reactor, and the operating pH of the cathode chamber is controlled to be ≤3, and the operating pH of the anode chamber is controlled to be 6-8. The dilute acid is in the cathode chamber, and the reverse osmosis concentrated concentrated water is in the anode chamber. Ultraviolet light is simultaneously applied to the anode chamber; hydrogen is obtained from the cathode chamber, and an anolyte mixed with sodium persulfate and sodium sulfate is obtained from the anode chamber; the reaction occurring in the anode chamber is: 2SO4 2- →S2O8 2- +2e - ; The reaction occurring in the cathode chamber is: 2H + +2e - →H2↑; The photoelectrolysis reactor is provided with a diaphragm, the composition of the diaphragm is a composite ceramic material of barium titanate and clay, and the mass ratio of the barium titanate to the clay is 1:(3.5-8.8); the anode of the photoelectrolysis reactor adopts a sub-titanium oxide electrode or a titanium-platinum electrode with a high oxygen evolution potential; the cathode of the photoelectrolysis reactor adopts a composite electrode with titanium as a substrate and zirconium, tantalum and ruthenium plated on the surface, and the mass ratio of titanium, zirconium, tantalum and ruthenium is (70-90):(2-3):(0.2-0.5):(0.2-0.5), and the hydrogen evolution potential of the cathode of the photoelectrolysis reactor is lower than -0.5V; the wavelength of the ultraviolet light is 185-365nm, and the intensity of the ultraviolet light is 200-500W / m 2 ; Performing crystallization separation on the anolyte to obtain sodium sulfate and sodium persulfate products; The reverse osmosis concentrated water is used to dissolve the mirabilite to obtain a saturated or nearly saturated sodium sulfate solution, which is returned to the photoelectrolysis treatment step for cyclic treatment.

2. The method for resource treatment of high-sulfate organic wastewater according to claim 1, characterized in that: The step of subjecting the high-sulfate organic wastewater to bipolar membrane separation treatment to obtain dilute alkali, dilute acid and dilute brine comprises: The high sulfate organic wastewater is treated by bipolar membrane separation through a bipolar membrane reactor with an average current density of 400-1000A / m 2 , to obtain dilute alkali, dilute acid and dilute brine; Wherein, the concentration of the dilute alkali is 1-2 mol / L, the concentration of the dilute acid is 1-2 mol / L, the TDS concentration in the dilute brine is 20000-40000 mg / L, and the COD concentration is 300-2000 mg / L; The volume ratio of the salt chamber, the alkali chamber and the acid chamber in the bipolar membrane reactor is (10.5-11.5): (7.5-8.5): (6.0-7.5).

3. The method for resource treatment of high-sulfate organic wastewater according to claim 1, characterized in that: In the step of evaporating and concentrating the dilute alkali to recover liquid alkali and condensed water, the evaporation operating temperature is 60-100° C., liquid alkali with an effective concentration of 20-30% is recovered, and the steam consumption is 0.4-0.6 t / t of dilute alkali.

4. The method for resource treatment of high-sulfate organic wastewater according to claim 1, characterized in that: In the step of performing crystallization separation on the anolyte to obtain mirabilite and sodium persulfate products, the operating temperature of the crystallization separation is -8 to 8° C., and the content of the sodium persulfate product produced by the crystallization separation is 250-350 g / L.

5. The method for resource treatment of high-sulfate organic wastewater according to claim 1, characterized in that: The step of using the reverse osmosis concentrated water to dissolve the mirabilite comprises: The reverse osmosis concentrated water is used to dissolve the mirabilite, so that the mirabilite is dissolved to form a saturated or nearly saturated sodium sulfate solution. The mass ratio of the reverse osmosis concentrated water to the mirabilite is (0.2-0.3):1, the dissolution temperature is controlled at 35-55°C, the dissolution residence time is 0.5-5min, and stirring is performed at the same time, and the stirring speed is 30-120r / min.

6. A high-sulfate organic wastewater resource treatment system, characterized in that: The invention comprises a bipolar membrane reactor, an electrocatalytic oxidation reactor, a disc-tube reverse osmosis membrane device, a photoelectrolytic reactor, a crystallization separation device, a dissolving crystal reactor and an evaporator. The dilute alkali output end of the bipolar membrane reactor is connected to the evaporator, the dilute brine output end of the bipolar membrane reactor is connected to the electrocatalytic oxidation reactor, the water production end of the electrocatalytic oxidation reactor is connected to the disc-tube reverse osmosis membrane device, the water inlet end of the photoelectrolytic reactor is respectively connected to the dilute acid output end of the bipolar membrane reactor and the concentrated water end of the disc-tube reverse osmosis membrane device, and the concentrated water produced by the disc-tube reverse osmosis membrane device and the dilute acid produced by the bipolar membrane reactor are respectively connected to the photoelectrolytic reactor. Electrolysis generates a mixed solution containing sodium persulfate and hydrogen. A hydrogen outlet is provided on the cathode side of the photoelectrolytic reactor. The anode side of the photoelectrolytic reactor is connected to the crystallization separation device. The crystallization separation device and the water production end of the disc-tube reverse osmosis membrane device are both connected to the crystal dissolution reactor. The crystal dissolution reactor is connected to the water inlet end of the photoelectrolytic reactor. The mixed solution containing sodium persulfate is separated by the crystallization separation device to obtain sodium persulfate, and a by-product, sodium sulfate, is separated. The sodium sulfate is washed and dissolved by the crystal dissolution reactor to obtain a saturated or nearly saturated sodium sulfate solution. The saturated or nearly saturated sodium sulfate solution is returned to the photoelectrolytic reactor for cyclic treatment.

7. The high-sulfate organic wastewater resource treatment system according to claim 6 is characterized in that: The photoelectrolytic reactor is provided with electrode plates and diaphragms, the electrode plates include anode mesh plates and cathode mesh plates, the anode mesh plates and the cathode mesh plates are alternately arranged in parallel, there are n anode mesh plates, and there are n+1 cathode mesh plates, the diaphragm is located between the alternately arranged anode mesh plates and cathode mesh plates, there are 2n diaphragms, water holes are evenly opened on the electrode plates, ultraviolet lamps are provided at the bottom and top of the photoelectrolytic reactor, and the ultraviolet lamps are vertically distributed to the electrode plates.

8. The high-sulfate organic wastewater resource treatment system according to claim 6 is characterized in that: The crystallization separation device includes a freezing reactor, a compressor, a condenser and a centrifuge. The photoelectrolysis reactor is connected to the water inlet end of the freezing reactor. A heat exchanger is arranged in the freezing reactor. The condenser, the heat exchanger and the compressor are connected in sequence. The compressor is connected to the condenser. The outlet end of the freezing reactor is connected to the centrifuge. A centrifugal feed pump is arranged between the freezing reactor and the centrifuge. The solid outlet end of the centrifuge is connected to the dissolution crystal reactor.

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