Wastewater recycling system for water electrolysis hydrogen production factory

Abstract

The invention relates to the technical field of water electrolysis hydrogen production, in particular to a wastewater recycling system for a water electrolysis hydrogen production factory. According to the technical scheme, the recycling system sequentially comprises a wastewater pretreatment system, a cascade membrane concentration system, a concentrated water hardness removal system, a forced induced crystallization deep defluorination reactor, a deamination system, an MVR (mechanical vapor recompression) evaporation system and an activated carbon adsorption device, the cascade membrane concentration system comprises an ultrafiltration module and at least one RO (reverse osmosis) membrane group, water vapor generated in the MVR evaporation system respectively enters the ultrafiltration module and the wastewater adjusting tank, on one hand, the temperatures of the ultrafiltration module and the wastewater adjusting tank are adjusted, and on the other hand, the dried water vapor is connected with the activated carbon adsorption device after being condensed. By deeply desalting the wastewater and optimizing the recycling process, zero discharge of the wastewater is realized, the energy efficiency level of the water electrolysis hydrogen production industry is effectively improved, and the industry cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of water electrolysis hydrogen production, and in particular to a wastewater recycling system for a water electrolysis hydrogen production plant. Background Art

[0002] As an ideal zero-carbon sustainable energy, hydrogen energy is considered to be an important part of the future energy system, and its related industries have broad development prospects. Hydrogen production by water electrolysis is a technology that uses the electrolysis reaction of water to produce hydrogen, and hydrogen produced by using renewable energy electricity is called "green hydrogen", which is the "ultimate route" of zero-carbon emission and sustainability. However, the current cost of hydrogen production by electrolysis is still a bottleneck factor restricting its popularization, and its large-scale application requires all links in the industrial chain to promote cost reduction. In the production process of large-scale electrolysis hydrogen production plants, there is a problem of generating a large amount of low-salt wastewater. The discharge and treatment of its wastewater will not only increase the cost of hydrogen production, but also cause waste of water resources. At this stage, the large-scale electric hydrogen production industry is still in the early demonstration stage, and there is still a lack of research and application of efficient and low-cost wastewater zero-discharge technology for large-scale electrolysis hydrogen production plants. Large-scale treatment of salt-containing wastewater still has the problems of low treatment efficiency and high operating costs. In view of the above reasons, this application proposes a wastewater recycling system for electrolysis hydrogen production plants with high efficiency, stability, low carbon and low cost. Summary of the Invention

[0003] The purpose of the present invention is to address the problems existing in the background technology and to propose a wastewater recycling system for a water electrolysis hydrogen production plant with high efficiency, stability, low carbon and low cost treatment.

[0004] The technical solution of the present invention is: a wastewater recycling system for a water electrolysis hydrogen production plant, the recycling system includes a wastewater pretreatment system, a cascade membrane concentration system, a concentrated water dehydration system, a forced induced crystallization deep defluorination reactor, a deammonification system, and an MVR evaporation system; the wastewater pretreatment system, the cascade membrane concentration system, the concentrated water dehydration system, the forced induced crystallization deep defluorination reactor, the deammonification system, and the MVR evaporation system are sequentially arranged through multiple pipelines; wherein, The wastewater pretreatment system is used to reduce the hardness of wastewater and remove Ca 2+ Mg 2+ The wastewater pretreatment system includes a wastewater regulating tank, a dual-alkali de-hardening device and a multi-media filter, which are connected in sequence to transport the pretreated wastewater to the cascade membrane concentration system. The cascade membrane concentration system includes an ultrafiltration module and at least one RO reverse osmosis membrane group, wherein the ultrafiltration module and the at least one RO reverse osmosis membrane group are sequentially connected in series and are respectively connected to the activated carbon adsorption device to transport fresh water and condensate to the activated carbon adsorption device; The MVR evaporation system adopts a combination of MVR technology and mother liquor drying. The evaporated water vapor enters the wastewater regulating tank and ultrafiltration module, and exchanges heat with the wastewater in the ultrafiltration module. Specifically, it includes an MVR evaporator and a mother liquor dryer. The water vapor generated by the mother liquor dryer enters the ultrafiltration module and the wastewater regulating tank respectively, on the one hand regulating the temperature of the ultrafiltration module and the wastewater regulating tank, and on the other hand, the dried water vapor is condensed and connected to the activated carbon adsorption device. It also includes an activated carbon adsorption device connected to the water supply facility of the electrolytic hydrogen production system, which is installed at the output end of the cascade membrane concentration system and the condensate output end of the MVR evaporation system to adsorb organic matter in the water and excess chloride after chlorination and deamination.

[0005] Optionally, it also includes a sludge thickening tank and a sludge filter press. The sludge treated by the concentrated water dehardening system, the forced induced crystallization deep defluorination reactor, and the double alkali dehardening equipment is transported to the sludge thickening tank, and is further treated by the sludge thickening tank and the sludge filter press before being discharged.

[0006] Optionally, the filtrate produced by the sludge thickening tank and the sludge filter press, the backwash water produced by the multi-media filter, and the concentrated water produced by the ultrafiltration module are all returned to the wastewater regulating tank.

[0007] Optionally, the concentrated water dehardening system and the double alkali method dehardening equipment respectively add alkali solution, sodium carbonate, flocculant and coagulant, and automatically adjust the amount of each added according to the water quality to deharden the wastewater.

[0008] Optionally, alkali solution is added to the double alkali dehardening equipment to adjust the pH value of the wastewater to 10-11.

[0009] Optionally, alkali solution is added to the concentrated water dehardening system to adjust the pH value of the concentrated water to 11-11.7.

[0010] Optionally, in the membrane separation process in the ultrafiltration module, the pressure of the wastewater inlet pump is used as the driving force. The liquid passes through the ultrafiltration membrane, and the large molecular particles are retained on one side of the membrane to become concentrated water, while the small molecular particles are carried to the other side with the solute to become permeate and flow out to the RO reverse osmosis membrane group; The pore size of the ultrafiltration membrane is 0.02-0.05 μm.

[0011] Optionally, the RO reverse osmosis membrane group comprises a first stage RO membrane, a second stage SWRO membrane and a third stage STRO membrane; wherein the RO reverse osmosis membrane group (22) has a fresh water yield greater than 94% and a desalination rate greater than 98%; The wastewater is concentrated through a first-stage RO membrane, a second-stage SWRO membrane, and a third-stage STRO membrane. The fresh water is transported to the activated carbon adsorption device for reuse. The concentrated water sequentially enters the concentrated water de-hardness system, the forced induced crystallization deep defluorination reactor, the deammoniation system, and the MVR evaporation system for further treatment, and finally evaporates in the MVR evaporation system.

[0012] Optionally, the forced induced crystallization deep defluorination reactor includes a three-zone defluorination reactor, wherein the concentrated water after dehardening from the concentrated water dehardening system enters the first zone, and acid is added to the first zone to adjust the pH value to 6.5-7. The wastewater with the adjusted pH value enters the second reaction zone, and a multi-point coordination defluoridating agent is added to the second zone. The dosage of each agent is automatically adjusted in real time mainly according to the water quality. The defluoridating agent is forced to complex and crystallize with the fluorine in the wastewater and then enters the flocculation and sedimentation zone. Flocculants and coagulants are added to the third flocculation and sedimentation zone to flocculate and precipitate the crystals for separation, and the concentrated water after defluorination enters the deammonification system for treatment; wherein the addition ratio of the defluoridating agent to the fluorine in the wastewater is 30:1~40:1, and the fluorine concentration in the effluent concentrated water is as low as 1 mg / L.

[0013] Optionally, sodium hypochlorite is added to the wastewater in the deammonification system, so that ammonia nitrogen reacts with sodium hypochlorite to form nitrogen gas, and sodium hypochlorite is reduced to chloride ions.

[0014] Optionally, the input end of the activated carbon adsorption device (7) is respectively connected to the fresh water output pipe of the RO reverse osmosis membrane group (22) and the water vapor condensation pipe after drying of the MVR evaporation system (6), and the output end of the activated carbon adsorption device (7) is connected to the recycled water tank of the electrolytic hydrogen production system.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: 1. Excellent effluent quality and high wastewater reuse rate: After treatment, the effluent pH is 6.5-7.5, fluoride <0.1 mg / L, total dissolved solids TDS <400 mg / L, total hardness <1 mg / L, and COD <10 mg / L, meeting the sanitary standards for drinking water (GB5749-2022: pH 6.5-8.5, fluoride <1 mg / L, total dissolved solids TDS <1000 mg / L, total hardness <450 mg / L) and the water quality standards for industrial water for urban sewage recycling (GB / T 19923-2024: pH 6-9, total dissolved solids TDS <1000 mg / L, total hardness <450 mg / L, etc.). Through the development of this technology, the wastewater reuse rate of the electrolytic hydrogen production system is >95%.

[0016] 2. High efficiency, stability, low carbon and low cost: The present invention conducts research on high efficiency, stability, low carbon and low cost treatment technology for low-salt wastewater from electrolytic water hydrogen production plants, providing a water-saving and emission reduction solution for the development of the electrolytic hydrogen production industry. At the same time, through the comprehensive utilization of thermal energy, the MVR system steam condensation recovery is realized through heat exchange with the regulating tank or ultrafiltration system to replace the traditional MVR system condenser, thereby reducing system energy consumption. The multiple types of treatment systems set up in sequence realize the gradual and cyclic treatment of industrial wastewater, thereby realizing a complete treatment process for electrolytic water hydrogen production. 3. Promote the water-saving and energy-saving development of electrolytic hydrogen production systems: The present invention achieves zero wastewater discharge, energy conservation and environmental protection by deeply desalting wastewater and optimizing the recycling process, effectively improving the energy efficiency level of the electrolytic water hydrogen production industry and reducing industry costs. It has a strong driving effect on the development of the industry and lays a solid foundation for the construction of a green, low-carbon and high-quality development pilot zone. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A process flow chart of the present invention is given.

[0018] Reference numerals: 1. Wastewater pretreatment system; 11. Wastewater regulating tank; 12. Double alkali de-hardening equipment; 13. Multi-media filter; 2. Cascade membrane concentration system; 21. Ultrafiltration module; 22. RO reverse osmosis membrane group; 3. Concentrated water de-hardening system; 4. Forced induced crystallization deep defluorination reactor; 5. Deammonification system; 6. MVR evaporation system; 7. Activated carbon adsorption device; 8. Sludge thickening tank; 9. Sludge filter press. DETAILED DESCRIPTION

[0019] The technical solutions of the present disclosure will be described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all of the embodiments.

[0020] The components of the embodiments of the present disclosure generally described and shown in the drawings herein may be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present disclosure provided in the drawings is not intended to limit the scope of the claimed disclosure, but merely represents selected embodiments of the present disclosure.

[0021] Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work shall fall within the scope of protection of the present disclosure.

[0022] In the description of the present disclosure, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present disclosure.

[0023] In the description of this disclosure, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this disclosure based on the specific circumstances.

[0024] Example: like Figure 1 As shown, the present invention proposes a wastewater recycling system for a water electrolysis hydrogen production plant. The recycling system specifically relies on the treatment process of a wastewater pretreatment system 1, a cascade membrane concentration system 2, a concentrated water de-hardening system 3, a forced induced crystallization deep defluorination reactor 4, a deamination system 5, an MVR evaporation system 6, an activated carbon adsorption device 7, a sludge concentration tank 8 and a sludge filter press 9. The sludge and miscellaneous salts generated in the treatment project are sent to a third-party waste treatment center for treatment; the wastewater pretreatment system 1, the cascade membrane concentration system 2, the concentrated water de-hardening system 3, the forced induced crystallization deep defluorination reactor 4, the deamination system 5, the MVR evaporation system 6 and the activated carbon adsorption device 7 are arranged in sequence through multiple pipelines; the products treated by the multi-media filter 13 and the ultrafiltration module 21 are again transported to the wastewater regulating tank 11 for a new round of recycling treatment; Wastewater pretreatment system 1 is used to reduce the hardness of wastewater and remove Ca 2+ Mg 2+and other substances to prevent the membrane system from being blocked; the wastewater pretreatment system 1 includes a wastewater regulating tank 11, a dual-alkali de-hardening device 12 and a multi-media filter 13, and the wastewater regulating tank 11, the dual-alkali de-hardening device 12 and the multi-media filter 13 are arranged in sequence; the water quality indicators such as wastewater quality, water volume, pH or temperature change greatly with the drainage time. In order to prevent the treatment structures or buildings from being impacted by the peak water volume or concentration of wastewater, the wastewater regulating tank 11 is used to treat the wastewater in a homogeneous and uniform manner to reduce the impact on the back-end system; the dual-alkali de-hardening device 12 removes the hardness of the wastewater by adding alkali, sodium carbonate, flocculants and coagulants; however, due to the high operating requirements of the electrolysis facilities in this project, a certain amount of scale inhibitors are added to the cooling circulating water and desalted water, which causes problems for the de-hardening of the wastewater. The wastewater of this project enters the first zone of the de-hardening reactor after passing through the regulating tank, and alkali solution is added to the first zone to adjust the pH value to the range of 10-11. After the pH value is adjusted, the wastewater enters the second zone, and sodium carbonate is added to the wastewater to capture the Ca in the wastewater. 2+ Mg 2+ and other substances, and at the same time, flocculants and coagulants are added to the wastewater. The wastewater after flocculation and precipitation enters the third zone of the reactor and acid is added to adjust the pH to 6.5-7, and then enters the multi-media filtration system; the multi-media filter 13 uses a filter medium to remove suspended impurities from water with higher turbidity to clarify the water. In this step, the water with higher turbidity passes through a granular or non-granular material of a certain thickness under a certain pressure, thereby effectively removing suspended impurities and clarifying the water. The filter medium can be any one of quartz sand, anthracite and manganese sand. Quartz sand is used in this embodiment.

[0025] The cascade membrane concentration system 2 includes an ultrafiltration module 21 and an RO reverse osmosis membrane group 22 for secondary treatment, wherein the ultrafiltration module 21 is used to further remove suspended matter in the wastewater; in the membrane separation process driven by the wastewater inlet pump pressure in the ultrafiltration module 21, the liquid passes through the ultrafiltration, and the ultrafiltration membrane retains the large molecular particles on one side of the membrane to become concentrated, while the small molecules flow to the other side with the solute and become the permeate; the pore size of the ultrafiltration membrane is 0.04μm; the RO reverse osmosis membrane group 22 consists of a first section of RO membrane, a second section of SWRO membrane and a third section of S It is composed of a TRO membrane; the wastewater is concentrated through a first stage RO membrane, a second stage SWRO membrane, and a third stage STRO membrane, the fresh water is reused, and the concentrated water enters the MVR evaporation system for evaporation; the RO reverse osmosis membrane is a membrane separation process driven by pressure. The reverse osmosis process is the reverse process of nature. In order to generate reverse osmosis pressure during use, a water pump is required to apply pressure to the salty wastewater to overcome the natural osmotic pressure, thereby allowing the water to pass through the reverse osmosis membrane, while impurities such as dissolved salt in the water are blocked on the other side of the reverse osmosis membrane.

[0026] The brine de-hardening system 3 removes the hardness of the brine output from the cascade membrane concentration system 2 by adding alkali, sodium carbonate, flocculants, and coagulants through flocculation and sedimentation. To prevent clogging of the membrane system and extend its service life, a scale inhibitor is added to the membrane system. During the membrane concentration purification process, the fresh water formed reaches the drinking water standard of pH 6.5-8.5, fluoride <1mg / L, total dissolved solids TDS <1000mg / L, and total hardness <450mg / L after being filtered through activated carbon. However, the brine significantly increases its TDS, fluoride, and total hardness due to membrane concentration. Therefore, the small amount of brine produced is de-hardened. Alkali solution is added to the brine de-hardening system 3 to adjust the pH value of the brine to the range of 11-11.7. A pH value below 11 will affect the subsequent flocculation effect. Scale inhibitors are added during the membrane treatment process, and their concentration increases significantly after membrane concentration. After the pH value is adjusted, the wastewater enters the second zone, where sodium carbonate is added to capture Ca in the wastewater. 2+ Mg 2+ At the same time, flocculants and coagulants are added to the wastewater, and the wastewater after flocculation and precipitation enters the defluorination reactor.

[0027] Forced induced crystallization deep defluorination reactor 4 is used to remove F from wastewater - Ions; The defluorination reactor proposed in Forced Induced Crystallization Deep Defluorination Reactor 4 utilizes a three-zone design. De-hardened concentrated water enters Zone 1, where acid is added to adjust the pH to 6.5-7. The wastewater with the adjusted pH enters Reaction Zone 2, where a multi-point coordination defluoridant is added. The defluoridant and fluoride in the wastewater are forced to complex and crystallize, then enter the flocculation and sedimentation zone. Flocculant and coagulant are added to Zone 3 to separate the crystals through flocculation and sedimentation. The defluoridant to fluoride ratio in the wastewater is 30:1-40:1, and the fluoride concentration in the concentrated water is as low as 1 mg / L.

[0028] After defluorination, the concentrated water enters the deamination system 5, which is a deamination tower. The deamination system 5 uses the breakpoint chlorination method to remove ammonia. Sodium hypochlorite is added to the wastewater to convert ammonia nitrogen into nitrogen gas, and the sodium hypochlorite is reduced to chloride ions. The MVR evaporation system 6 is implemented by combining the MVR process with mother liquor drying. The MVR process has the characteristics of small footprint and low operating energy consumption. The MVR evaporation system 6 includes an MVR evaporator and a mother liquor dryer. The water vapor generated by the mother liquor dryer enters the ultrafiltration module 21 and the wastewater regulating tank 11 respectively to adjust the temperature of the ultrafiltration module 21 and the wastewater regulating tank 11. The evaporated water vapor (150°C) enters the ultrafiltration module 21 and exchanges heat with the wastewater in the ultrafiltration module 21. On the one hand, the operating temperature of the ultrafiltration module 21 is maintained between 5-25°C. On the other hand, the water vapor condenses and enters the activated carbon adsorption device 7. After treatment, it is used for domestic drinking water or reused in the desalination station or circulating water field of the electrolytic hydrogen production system. The evaporated crystalline salt is outsourced for treatment. The activated carbon adsorption device 7 is installed at the output of the cascade membrane concentration system 2 and the condensate output of the MVR evaporation system 6. By utilizing the large surface area of ​​the activated carbon to adsorb organic matter in the water and excess chloride after chlorination and deammoniation, it ensures that the effluent meets drinking water standards and the requirements of cooling water and desalted water for the electrolytic hydrogen production system. Specifically, the input end of the activated carbon adsorption device 7 is connected to the fresh water output pipeline of the RO reverse osmosis membrane group 22 and the water vapor condensation pipeline after drying in the MVR evaporation system 6, and the output end of the activated carbon adsorption device 7 is connected to the recycled water tank of the electrolytic hydrogen production system. The output of the activated carbon adsorption device 7 accounts for more than 95% of the total amount of saline wastewater and cooling circulation tower wastewater from the electrolytic hydrogen production system. The activated carbon adsorption device 7 has an outlet water pH of 6.5-7.5, a total dissolved solids (TDS) concentration of less than 400 mg / L, fluorine of less than 0.1 mg / L, a total hardness of less than 1 mg / L, and a COD of less than 10 mg / L.

[0029] The above specific embodiment is merely an optional embodiment of the present invention. Based on the technical solution of the present invention and the relevant inspiration of the above embodiment, those skilled in the art can make various alternative improvements and combinations to the above specific embodiment.

Claims

1. A wastewater recycling system for a water electrolysis hydrogen production plant, characterized in that: include: The wastewater pretreatment system (1), the cascade membrane concentration system (2), the concentration and de-hardening system (3), the forced induced crystallization deep defluorination reactor (4), the deammoniation system (5), and the MVR evaporation system (6) are connected in sequence; wherein: The wastewater pretreatment system (1) comprises a wastewater regulating tank (11), a double alkali de-hardening device (12) and a multi-media filter (13) connected in sequence, and is used to remove salt-containing wastewater and Ca in cooling circulation tower wastewater. 2+ Mg 2+ Substances to reduce the hardness of wastewater; A cascade membrane concentration system (2) receives the pretreated wastewater, the cascade membrane concentration system (2) comprising an ultrafiltration module (21) and at least one group of RO reverse osmosis membrane groups (22), wherein the ultrafiltration module (21) and at least one group of RO reverse osmosis membrane groups (22) are sequentially connected in series to further remove suspended matter in the wastewater; The concentrate de-hardening system (3) removes the hardness of the concentrate outputted from the cascade membrane concentration system (2) by means of flocculation and sedimentation; Forced induced crystallization deep defluorination reactor (4) for removing F from wastewater - ion; The deammonification system (5) uses a breakpoint chlorination method to remove ammonia. Sodium hypochlorite is added to the wastewater in the deammonification system (5) so that ammonia nitrogen reacts with sodium hypochlorite to form nitrogen gas, and the sodium hypochlorite is reduced to chloride ions. An MVR evaporation system (6) comprises an MVR evaporator and a mother liquor dryer, wherein the water vapor generated by the mother liquor dryer enters the ultrafiltration module (21) and the wastewater regulating tank (11) respectively to adjust the temperature of the ultrafiltration module (21) and the wastewater regulating tank (11), and the dried water vapor is condensed and connected to the activated carbon adsorption device (7); It also includes an activated carbon adsorption device (7), which is installed at the output end of the cascade membrane concentration system (2) and the output end of the MVR evaporation system (6) and is used to adsorb organic matter in water and excess chloride after chlorination and deammoniation.

2. A wastewater recycling system for hydrogen production from water electrolysis plant according to claim 1, characterized in that: It also includes a sludge concentration tank (8) and a sludge filter press (9). The sludge treated by the concentrated water de-hardening system (3), the forced induced crystallization deep defluorination reactor (4), and the double alkali de-hardening equipment (12) is transported to the sludge concentration tank (8), and is further treated by the sludge concentration tank (8) and the sludge filter press (9) before being discharged.

3. A wastewater recycling system for a water electrolysis hydrogen production plant according to claim 2, characterized in that: The filtrate produced by the sludge concentration tank (8) and the sludge filter press (9), the backwash water produced by the multi-media filter (13), and the concentrated water produced by the ultrafiltration module (21) are all returned to the wastewater regulating tank (11).

4. A wastewater recycling system for a water electrolysis hydrogen production plant according to claim 1, characterized in that: The concentrated water de-hardening system (3) and the double alkali de-hardening device (12) respectively perform de-hardening treatment on the wastewater by adding alkali solution, sodium carbonate, flocculant and coagulant.

5. A wastewater recycling system for a water electrolysis hydrogen production plant according to claim 4, characterized in that: Alkali solution is added into the double alkali de-hardening device (12) to adjust the pH value of the wastewater to 10-11.

6. A wastewater recycling system for a water electrolysis hydrogen production plant according to claim 4, characterized in that: Alkali solution is added to the concentrated water de-hardening system (3) to adjust the pH value of the concentrated water to 11-11.

7.

7. A wastewater recycling system for a water electrolysis hydrogen production plant according to claim 1, characterized in that: The ultrafiltration module (21) is a membrane separation process using the pressure of the wastewater inlet pump as a driving force. Liquid passes through the ultrafiltration membrane to retain large molecular particles on one side of the membrane to become concentrated water, while small molecular particles flow along with the solute to the other side to become permeate and flow out to the RO reverse osmosis membrane group (22); The pore size of the ultrafiltration membrane is 0.02-0.05 μm.

8. A wastewater recycling system for a water electrolysis hydrogen production plant according to claim 7, characterized in that: The RO reverse osmosis membrane group (22) comprises a first stage RO membrane, a second stage SWRO membrane and a third stage STRO membrane; The RO reverse osmosis membrane group (22) has a fresh water yield of >94% and a desalination rate of >98%; The wastewater is concentrated by a first-stage RO membrane, a second-stage SWRO membrane, and a third-stage STRO membrane. The fresh water is transported to the activated carbon adsorption device (7) for reuse. The concentrated water sequentially enters the concentrated water de-hardening system (3), the forced induced crystallization deep defluorination reactor (4), the deammoniation system (5), and the MVR evaporation system (6) for further treatment. Finally, it is evaporated in the MVR evaporation system (6). The water vapor dried in the MVR evaporation system (6) is condensed and enters the activated carbon adsorption device (7).

9. A wastewater recycling system for a water electrolysis hydrogen production plant according to claim 1, characterized in that: The forced induced crystallization deep defluorination reactor (4) comprises a defluorination reactor arranged in three zones, wherein the concentrated water after dehardening of the concentrated water dehardening system (3) enters the first zone, and acid is added to the first zone to adjust the pH value to 6.5-7. The wastewater with the adjusted pH value enters the second reaction zone, and a multi-point coordination defluorination agent is added to the second zone. The defluorination agent is forced to complex and crystallize with the fluorine in the wastewater and then enters the flocculation and precipitation zone. Flocculants and coagulants are added to the third flocculation and precipitation zone to flocculate and precipitate the crystals and separate them. The concentrated water after defluorination enters the deammonification system (5) for denitrification treatment; The addition ratio of defluoridating agent to fluoride in wastewater is 30:1~40:1, and the fluoride concentration in the concentrated water is as low as 1 mg / L.

10. The wastewater recycling system of a water electrolysis hydrogen production plant according to claim 1, characterized in that: The input end of the activated carbon adsorption device (7) is respectively connected to the fresh water output pipeline of the RO reverse osmosis membrane group (22) and the condensation pipeline of the water vapor after drying of the MVR evaporation system (6), and the output end of the activated carbon adsorption device (7) is connected to the recycled water tank of the electrolytic hydrogen production system.

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