Urea-containing wastewater hydrogen production collaborative resource recycling system and method

Abstract

The invention provides a urea-containing wastewater hydrogen production synergistic resource recycling system and a urea-containing wastewater hydrogen production synergistic resource recycling method, which are used for carrying out resource utilization and harmless treatment on urea-containing wastewater by adopting an electro-catalysis urea oxidation auxiliary water electrolysis hydrogen production and membrane distillation resource recycling technology. The treatment mode is suitable for being combined with green electricity, is convenient and easy to operate, and is suitable for large-scale urea-containing wastewater treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a system and method for cooperative resource recycling of urea-containing wastewater producing hydrogen. Background Art

[0002] The treatment and resource utilization of urea-containing wastewater is one of the important challenges currently faced in the field of environmental protection and sustainable development. With the acceleration of industrialization, especially in industries such as fertilizer production and urea resin manufacturing, the amount of urea-containing wastewater is increasing. If this type of wastewater is directly discharged without proper treatment, it will cause serious pollution to the water environment, lead to eutrophication of water bodies, and destroy the ecological balance.

[0003] Therefore, it has become a top priority to develop efficient and economical urea-containing wastewater treatment technologies. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a system and method for urea-containing wastewater to produce hydrogen and coordinate resource recycling.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] The present invention provides a urea-containing wastewater hydrogen production collaborative resource recycling system, the system comprises a storage bin, a urea-assisted water electrolysis system, a membrane distillation system and a condensed water tank which are connected in sequence; the storage bin is also connected to the membrane distillation system, the urea-assisted water electrolysis system is connected to a green electricity generation system, the green electricity generation system is used to provide electrical energy to the system; the condensed water tank is also connected to the membrane distillation system again through a refrigeration device; wherein the storage bin is used to access a urea wastewater source, perform alkali treatment and heating treatment on the urea-containing wastewater generated by the pretreatment of the urea wastewater source, and transport the treated urea-containing wastewater to a refrigerated storage tank; to the urea-assisted water electrolysis system; the urea-assisted water electrolysis system is used to electrolyze the urea-containing wastewater, and use the generated hydrogen for recovery, other gases are directly discharged, and the effluent is transported to the membrane distillation system; the membrane distillation system is used to concentrate the urea-containing wastewater, and pump out the generated hot end concentrated liquid or transport it to the storage bin again for the next round of circulation treatment, and condense the generated steam into condensed water and transport it to the condensation water tank; the condensation water tank is used to store condensed water, or transport the condensed water to a refrigeration device to generate cooling water as make-up water and transport it to the membrane distillation system as a supplementary electrolyte.

[0007] Furthermore, the storage bin includes a bin body, a dosing device is provided on the top of the bin body, a heating device is provided on the bottom, and a pH monitoring probe is provided on the inner wall of the bin body; the dosing device is used to perform alkali treatment on the urea-containing wastewater; the heating device is used to perform heat treatment on the urea-containing wastewater; and the pH monitoring probe is used to monitor the pH value of the urea-containing wastewater.

[0008] Furthermore, the membrane distillation system includes a cold end and a hot end, the cold end and the hot end are separated by a hydrophobic microporous membrane, the cold end is used to pump in cooling water, and the hot end is used to receive urea-containing wastewater treated by the urea-assisted water electrolysis system, and cooperate with the cold end to concentrate the urea-containing wastewater; wherein the hydrophobic microporous membrane is made of polytetrafluoroethylene.

[0009] Furthermore, a liquid level monitoring probe is provided in the urea-assisted water electrolysis system, and a liquid level monitoring probe is provided in the condensed water tank.

[0010] Furthermore, a pump is provided between the urea-assisted water electrolysis system and the membrane distillation system, and a pump is also provided between the condensed water tank and the refrigeration device.

[0011] The present invention also provides a method for synergistic resource recycling by producing hydrogen from urea-containing wastewater, which is applied to the system as described above; the method comprises the following steps: the urea-containing wastewater enters a storage bin; the urea-containing wastewater is subjected to alkali treatment and heating treatment, and the effluent is transported to a urea-assisted water electrolysis system; the urea-containing wastewater is subjected to electrolysis treatment, and the generated hydrogen is used for recovery, other gases are directly discharged, and the effluent is transported to a membrane distillation system; the urea-containing wastewater is concentrated, and the generated hot end concentrated liquid is pumped out or transported again to a storage bin for the next round of circulation treatment, and the generated condensed water is transported to a condensed water tank; the condensed water is stored, or transported to a refrigeration device to generate cooling water as make-up water and transported to a membrane distillation system as a supplementary electrolyte.

[0012] Furthermore, the method specifically includes the following steps: the urea-containing wastewater enters the storage bin after pretreatment such as flocculation and filtration; the pH of the urea-containing wastewater in the storage bin is monitored, the dosing device is started and the heating device is started; the urea-containing wastewater in the storage bin is pumped into the anode end of the electrolytic cell in the urea-assisted water electrolysis system, the cathode end is a potassium hydroxide solution, and the anode and cathode are separated by an anion exchange membrane; after applying voltage to the electrolytic cell, high-purity hydrogen is recovered at the upper end of the cathode, and the gas (mainly nitrogen) generated at the anode is directly discharged; the water at the end of the anode end directly enters the hot end of the membrane distillation system; and the water is pumped into the circulating water at the cold end. Cooling water is used; due to the temperature difference between the hot and cold end feed liquids, water in the form of water vapor passes through the hydrophobic microporous membrane of polytetrafluoroethylene from the hot end to the cold end for condensation, and the hot end feed liquid is concentrated into a hot end concentrated liquid; the hot end concentrated liquid carries almost all the potassium hydroxide and urea in the hot end feed liquid, and the hot end concentrated liquid is pumped out of the membrane distillation system or directly enters the storage bin for the next round of circulation treatment; the steam generated in the membrane distillation system is directly brought into the cooling water for condensation, and can continue to be used as cooling water, or as make-up water to supplement urea-assisted water electrolysis cathode electrolyte, or be used for other purposes after simple treatment.

[0013] Furthermore, the steps of starting the dosing device and starting the heating device specifically include: starting the dosing device to add potassium hydroxide to a pH value of the urea-containing wastewater of 14; and starting the heating device to control the temperature of the urea-containing wastewater at 70°C.

[0014] Furthermore, the temperature of the cooling water is 10-15°C.

[0015] Furthermore, when the urea concentration of the urea-containing wastewater is 20 g / L, the hydrogen production is 0.77 Nm 3 / h.

[0016] Compared with the prior art, the technical solution provided by the present invention has at least the following advantages:

[0017] The present invention provides a system and method for the coordinated resource recycling of urea-containing wastewater with hydrogen production, which uses electrocatalytic urea oxidation to assist water electrolysis in hydrogen production and membrane distillation resource recycling technology to perform resource utilization and harmless treatment of urea-containing wastewater. This treatment method is suitable for use with green electricity, is convenient and easy to operate, and is suitable for large-scale urea-containing wastewater treatment.

[0018] After the pre-purified urea-containing wastewater enters the storage bin, potassium hydroxide is added and heated. After the temperature rises, it enters the anode end of the electrolytic cell, and the circulating potassium hydroxide solution is pumped into the cathode end. The anode and cathode are separated by an anion exchange membrane. After power-on operation, hydrogen is generated in the cathode tank, which can be used by simple collection. The urea in the urea wastewater in the anode is oxidized into nitrogen and carbonate, both of which are non-toxic substances.

[0019] After a round of electrolysis reaction in the electrolytic cell, urea wastewater directly enters the hot end of the membrane distillation system, and circulating cooling water is introduced into the cold end, separated by a hydrophobic microporous membrane. Due to the temperature difference on both sides of the membrane and the difference in vapor pressure, water vapor molecules pass through the micropores and condense on the other side, gradually concentrating the solution. The condensed water produced during the distillation process can be recycled after refrigeration, or it can be disinfected and used for other purposes. The distillation process recovers most of the solutes in the wastewater, so the remaining concentrated water can be directly sent to the urea wastewater storage bin for the next cycle.

[0020] This method can truly realize the resource utilization of urea-containing wastewater. Compared with the electrolysis of water to produce hydrogen, it can save a lot of energy. At the same time, due to the addition of membrane distillation components, low-content urea wastewater can be efficiently utilized, and the produced clean water only needs simple treatment and will not cause secondary pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a urea-containing wastewater hydrogen production and resource recycling system provided by an embodiment of the present invention.

[0022] In the figure, 1-urea wastewater source, 2-green electricity generation system, 3-storage bin, 4-urea assisted water electrolysis system, 5-pump, 6-membrane distillation system, 7-refrigeration device, 8-condensate tank, 31-dosing device, 32-heating device, 33-pH monitoring probe, 41-liquid level monitoring probe, 61-hydrophobic microporous membrane, 81-liquid level monitoring probe. DETAILED DESCRIPTION

[0023] Based on the problem of improving the treatment technology of urea-containing wastewater in the prior art. The inventors found that the global energy structure is undergoing profound changes, and hydrogen, as a clean and efficient energy carrier, is receiving more and more attention. Hydrogen can be used in many fields such as fuel cells and industrial production, and is regarded as an important part of the future energy system. However, traditional hydrogen production methods, such as fossil fuel reforming and water electrolysis, often have problems such as high energy consumption, high cost or insufficient environmental friendliness. Therefore, finding new and sustainable hydrogen production methods has become a research hotspot.

[0024] In this context, a technical solution combining urea-containing wastewater treatment with hydrogen production has emerged. This method can not only effectively treat wastewater, but also produce high-value hydrogen at the same time, reflecting the concept of resource recycling. Among many technical routes, electrocatalytic urea oxidation has attracted widespread attention due to its unique advantages. This method uses electrochemical principles to carry out urea oxidation reaction on the electrode surface, which can not only effectively degrade urea, but also produce hydrogen simultaneously.

[0025] It is worth noting that with the rapid development of renewable energy technology, the combination of green electricity and electrocatalytic urea oxidation technology has become a very promising research direction. The cost of renewable energy generation technologies such as solar and wind power continues to decline, providing clean, low-carbon energy input for the electrocatalytic process. This combination can not only further reduce the carbon emissions of the entire system, but also effectively utilize the volatility and intermittent characteristics of renewable energy generation to provide support for grid peak and frequency regulation. For example, during the peak period of photovoltaic power generation, excess electricity can be used to drive the electrocatalytic urea oxidation process, converting electrical energy into chemical energy and storing it in the form of hydrogen, achieving efficient energy utilization and smooth conversion.

[0026] Compared with traditional water electrolysis to produce hydrogen, electrocatalytic urea oxidation has a lower theoretical voltage, which means lower energy consumption and higher energy efficiency. When green electricity is used to drive this process, it can not only achieve harmless treatment of wastewater, but also produce truly "green hydrogen", contributing to the establishment of a clean, low-carbon hydrogen energy economy system. This synergistic effect fully reflects the deep integration of environmental protection, resource utilization and renewable energy applications, and represents an important direction for future sustainable development.

[0027] The development of this technology not only complies with the current environmental protection policy orientation, but also meets the market's dual needs for efficient and low-cost wastewater treatment and clean energy production. Many countries and regions have introduced policies and measures to support the development of clean energy and resource recycling, creating favorable conditions for the research and development and application of related technologies. In the long run, the technology of hydrogen production and resource recycling from urea-containing wastewater is expected to find wide application in chemical, agricultural, municipal and other fields, with significant environmental benefits and economic value.

[0028] In view of this, the present invention provides a urea-containing wastewater hydrogen production and collaborative resource recycling system, which includes a storage bin 3, a urea-assisted water electrolysis system 4, a membrane distillation system 6 and a condensed water tank 8 connected in sequence; the storage bin 3 is also connected to the membrane distillation system 6, and the urea-assisted water electrolysis system 4 is connected to a green electricity generation system 2, which is used to provide electrical energy to the system. The condensate tank 8 is also connected to the membrane distillation system 6 again through the refrigeration device 7; wherein, the storage bin 3 is used to access the urea wastewater source 1, and the urea-containing wastewater generated by the pretreatment of the urea wastewater source 1 is subjected to alkali treatment and heating treatment, and the treated urea-containing wastewater is transported to the urea-assisted water electrolysis system 4; the urea-assisted water electrolysis system 4 is used to electrolyze the urea-containing wastewater, and use the generated hydrogen for recovery, directly discharge other gases, and transport the effluent to the membrane distillation system 6; the membrane distillation system 6 is used to concentrate the urea-containing wastewater, and pump out the generated hot end concentrated liquid or transport it to the storage bin 3 again for the next round of circulation treatment, and condense the generated steam into condensate and transport it to the condensate tank 8; the condensate tank 8 is used to store condensate, or transport the condensate to the refrigeration device 7 to generate cooling water as make-up water and transport it to the membrane distillation system 6 as a supplementary electrolyte.

[0029] Specifically, the storage bin 3 includes a bin body, a dosing device 31 is provided on the top of the bin body, a heating device 32 is provided on the bottom, and a pH monitoring probe 33 is also provided on the inner wall of the bin body; the dosing device 31 is used to add alkali to the urea-containing wastewater; the heating device 32 is used to heat the urea-containing wastewater; the pH monitoring probe 33 is used to monitor the pH value of the urea-containing wastewater.

[0030] More specifically, the membrane distillation system 6 includes a cold end and a hot end, which are separated by a hydrophobic microporous membrane 61. The cold end is used to pump in cooling water, and the hot end is used to receive urea-containing wastewater treated by the urea-assisted water electrolysis system, and cooperate with the cold end to concentrate the urea-containing wastewater; wherein the hydrophobic microporous membrane 61 is made of polytetrafluoroethylene.

[0031] In addition, a liquid level monitoring probe 41 is provided in the urea-assisted water electrolysis system 4, and a liquid level monitoring probe 81 is provided in the condensed water tank 8. A pump 5 is provided between the urea-assisted water electrolysis system 4 and the membrane distillation system 6, and a pump 5 is also provided between the condensed water tank 8 and the refrigeration device 7.

[0032] The present invention also provides a method for synergistic resource recycling of hydrogen production from urea-containing wastewater, which is applied to the above-mentioned system; the method comprises the following steps:

[0033] The urea-containing wastewater enters storage bin 3;

[0034] The urea-containing wastewater is subjected to alkali treatment and heating treatment, and the effluent is transported to the urea-assisted water electrolysis system 4;

[0035] Electrolyze the urea-containing wastewater, and use the generated hydrogen for recovery, and directly discharge other gases, and transport the effluent to the membrane distillation system 6;

[0036] The urea-containing wastewater is concentrated, and the hot end concentrated liquid produced is pumped out or transported again to the storage bin 3 for the next round of circulation treatment, and the produced condensed water is transported to the condensed water tank 8;

[0037] The condensed water is stored or sent to a refrigeration device 7 to generate cooling water as supplementary water and sent to a membrane distillation system 6 as supplementary electrolyte.

[0038] The present invention is described in detail below in conjunction with specific implementation modes.

[0039] Embodiment 1:

[0040] like Figure 1 As shown, the embodiment of the present invention provides a urea-containing wastewater hydrogen production collaborative resource recycling system, which is mainly composed of a urea wastewater source, a green electricity generation system, an electrocatalytic urea oxidation system, a membrane distillation system, etc. The urea wastewater source 1, the green electricity generation system 2, the storage bin 3, the urea-assisted water electrolysis system 4, the pump 5, the membrane distillation system 6, the refrigeration device 7, and the condensed water tank 8 are connected through various pipelines and valves.

[0041] At the same time, an embodiment of the present invention provides a method for synergistic resource recycling of hydrogen production from urea-containing wastewater, which is applied to the system as described above. The green electricity generation system 2 supplies electricity for the entire process. The urea-containing wastewater discharged from the urea wastewater source 1 enters the storage bin 3 after pre-treatment operations such as filtration and impurity removal. By controlling the dosing device 31 to perform alkali treatment, the pH monitoring probe 33 detects that the pH of the solution meets the standard, and after being heated to 70°C by the heating device 32, the treated strong alkaline urea wastewater is pumped into the anode end of the urea-assisted water electrolysis system 4 to perform a urea decomposition reaction. Nitrogen will be generated above the anode, which is non-toxic and harmless and does not require treatment; the cathode end is a potassium hydroxide solution, which will consume water over time. It only needs to monitor the liquid level and replenish water. Hydrogen will be generated above the cathode, which should be sealed for collection. The water discharged from the anode terminal of the urea-assisted water electrolysis system 4 is pumped into the hot end and the cold end of the membrane distillation system 6, and the circulating cooling water of 10-15°C is pumped into the cold end; the hot and cold ends are separated by a hydrophobic microporous membrane 61 of polytetrafluoroethylene, and the water vapor generated at the hot end of the membrane distillation system crosses the membrane into the cold end and condenses into water, participating in the cooling water circulation. The hot end feed liquid is concentrated into the hot end concentrated liquid and discharged into the storage bin 3 for reuse. The condensation water tank 8 is provided with a liquid level monitoring probe 81, and the liquid level increases with the increase of water production. When the upper limit is reached, part of the condensed water can be discharged and can be used as supplementary water to supplement the urea-assisted water electrolysis cathode electrolyte, or for other uses after simple treatment. It can be seen that the method for coordinated resource recycling of urea-containing wastewater hydrogen production provided by the present invention can realize the harmless treatment and resource utilization of urea-containing wastewater.

[0042] Embodiment 2:

[0043] like Figure 1 As shown, the embodiment of the present invention provides a method for producing hydrogen from urea-containing wastewater and coordinating resource recycling, which not only achieves efficient wastewater treatment, but also can produce high-purity hydrogen, reflecting the advanced concept of resource recycling. The design of the entire system fully considers energy efficiency and environmental friendliness, especially by introducing green electricity, further improving the sustainability of the system.

[0044] First, the urea-containing wastewater provided by the chemical plant is pre-treated to remove most of the insoluble precipitates and then discharged into the storage bin 3 for standby use. An intelligent dosing device 31, a heating device 32 and a pH monitoring probe 33 are provided in the storage to accurately control the pH of the urea-containing wastewater to 14 and the temperature to 70°C. The precise control of these parameters is crucial to the efficiency of the subsequent electrolysis and membrane distillation processes. Taking the treatment of 50L of urea-containing wastewater with a urea concentration of 20g / L as an example (this concentration is generally the optimal concentration for urea oxidation. If the concentration is too low, it can be enriched by membrane distillation equipment first), the amount of potassium hydroxide to be added is about 3kg. The design of the storage bin takes into account the requirements of corrosion protection and thermal insulation to ensure the safety and stability of the wastewater treatment process.

[0045] The urea-containing wastewater in the storage bin 3 is pumped into the anode end of the urea-assisted water electrolysis system 4 at a uniform flow rate through a precision flow control pump. The electrolysis system uses the latest electrode materials and structural design, which greatly improves the electrolysis efficiency. 2 Electrochemical reaction area, 2000A / m 2 Taking the current density as an example, the time required to treat 50L of wastewater is about 1.45 hours, the average urea consumption per hour is about 690g / h, and the hydrogen production is 0.77Nm 3 / h, the DC power consumption under standard conditions is 4.15kWh / Nm 3 . It is worth noting that the system's electricity supply gives priority to renewable energy generation, such as solar photovoltaic or wind power generation. During the peak period of renewable energy generation, excess green electricity can be fully utilized to drive the electrolysis process, which not only reduces the system's carbon emissions, but also provides support for grid peak and frequency regulation. When the supply of renewable energy is insufficient, the system can seamlessly switch to conventional grid power supply to ensure continuity of operation. The hydrogen produced by the electrolysis process is of high purity and can be used without further purification, which greatly reduces post-processing costs. The high-purity hydrogen produced can be directly used in fuel cells, industrial production or energy storage systems, contributing to the establishment of a clean, low-carbon hydrogen energy economy.

[0046] The electrolyte flowing out of the anode end is pumped into the hot end of the membrane distillation system 6, and the cold end is pumped into the circulating cooling water. The membrane distillation system 6 adopts an efficient heat recovery design, which maximizes the use of the waste heat generated by the electrolysis process and further improves the energy efficiency of the entire system. The water production per unit area of ​​the system is 12L / h·m 2 In order to match the urea consumption of the urea-assisted water electrolysis system, the membrane area of ​​the polytetrafluoroethylene hydrophobic microporous membrane is set to 3m 2 The selection of membrane materials takes into account both high flux and long-term stability, ensuring the continuous and efficient operation of the system. The concentrated liquid flowing out of the hot end returns to the storage bin 3, realizing the recycling of urea and potassium hydroxide, and improving the resource utilization efficiency of the whole process. The water produced by the cold end can be used to supplement the water consumed by the cathode, forming a closed-loop water resource circulation system. The excess water can be purified and used in other industrial processes or park greening, further reflecting the comprehensive utilization of resources.

[0047] The operation of the entire system is monitored by an intelligent control system, including real-time monitoring of operating parameters of each link, such as pH value, temperature, current density, hydrogen production, etc., and automatically adjusts the operating status according to these parameters to ensure that the system operates at the optimal efficiency point. At the same time, the system is also equipped with remote monitoring and data analysis functions, which makes it easy for managers to grasp the operating status in real time and optimize the operating strategy.

[0048] This innovative method for treating urea-containing wastewater not only efficiently solves the problem of environmental pollution, but also achieves energy recovery and resource recycling, especially by introducing green electricity, making the entire process more environmentally friendly and sustainable. It represents the deep integration of wastewater treatment, hydrogen production and renewable energy application, and provides a model for building a circular economy and sustainable development.

[0049] Embodiment 3:

[0050] like Figure 1 As shown, a method for synergistic resource recycling of urea-containing wastewater producing hydrogen provided by an embodiment of the present invention specifically comprises the following steps:

[0051] Step 1: The urea-containing wastewater provided by the chemical plant is pre-treated to remove most of the insoluble precipitates and then discharged into the storage bin 3 for standby use;

[0052] Step 2: The storage bin 3 is provided with a dosing device 31, a heating device 32 and a pH monitoring probe 33, which are used to adjust the pH of the urea-containing wastewater to 14 and the temperature to 70°C; taking the treatment of 50L of urea-containing wastewater with a urea concentration of 20g / L as an example, the amount of potassium hydroxide to be added is about 3kg;

[0053] Step 3: The urea-containing wastewater in the storage bin 3 is pumped into the anode end of the urea-assisted water electrolysis system 4 at a uniform flow rate of 1 m 2 Electrochemical reaction area, 2000A / m 2 Taking the current density as an example, the time required to treat 50L of wastewater is about 1.45 hours;

[0054] Step 4: During the electrolysis process, the average urea consumption per hour is about 690g / h, and the hydrogen production is 0.77Nm 3 / h, the DC power consumption under standard conditions is 4.15kWh / Nm 3 ; The hydrogen produced is of high purity and can be used without further purification;

[0055] Step 5: The electrolyte flowing out from the anode end is pumped into the hot end of the membrane distillation system 6, and the cold end is pumped into the circulating cooling water; the water production per unit area of ​​the membrane distillation system is 12L / h·m 2 In order to match the urea consumption of the urea-assisted water electrolysis system, the membrane area of ​​the polytetrafluoroethylene hydrophobic microporous membrane should be set to 3m 2 ;

[0056] Step 6: The concentrated liquid flowing out from the hot end returns to the storage bin 3, and the output liquid from the cold end can be used to supplement the water consumed by the cathode or for other purposes.

[0057] It should be noted that the preliminary pretreatment in step 1 mainly includes physical methods such as filtration and sedimentation to remove insoluble impurities and ensure the stability of subsequent treatment.

[0058] In step 2, precise control of pH and temperature is crucial to improving urea oxidation efficiency. If the urea concentration in the wastewater is lower than 20 g / L, it can be preferentially enriched by membrane distillation equipment to achieve the best oxidation effect.

[0059] In step 3, the design of the electrolysis system uses the latest electrode materials and structures, which greatly improves the electrolysis efficiency. The control of the pumping flow rate needs to accurately match the processing capacity of the electrolysis system.

[0060] In step 4, the electrolysis process gives priority to using renewable energy sources, such as solar or wind power, to reduce the system's carbon emissions. When renewable energy supply is insufficient, it can seamlessly switch to conventional grid power supply to ensure operational continuity.

[0061] In step 5, the membrane distillation system 6 adopts a high heat recovery design to maximize the use of waste heat generated by the electrolysis process, further improving the energy efficiency of the entire system.

[0062] In step 6, the recycling of the concentrated liquid improves the resource utilization efficiency of the entire process. In addition to replenishing the water consumed by the cathode, the excess water produced by the cold end can be purified and used in other industrial processes or park greening, further reflecting the comprehensive utilization of resources.

[0063] The method for synergistic resource recycling of hydrogen production from urea-containing wastewater provided by the present invention has significant advantages over the prior art. Traditional methods for treating urea-containing wastewater mainly include biological methods and chemical methods, and these methods have many problems. The biological method has a long treatment cycle and low efficiency, and is easily affected by environmental factors such as temperature and pH, and has poor stability. Although the chemical method is more efficient, it often requires a large amount of chemical agents, which is not only costly, but may also cause secondary pollution. In addition, most of the existing urea wastewater treatment methods only focus on the harmless treatment of wastewater, ignoring the value of resources contained therein, such as hydrogen energy. In the prior art, urea wastewater treatment and hydrogen production are usually carried out separately, and there is a lack of efficient solutions for synergistic treatment. At the same time, traditional methods often have high energy consumption and fail to make full use of renewable energy.

[0064] In contrast, the present invention proposes an innovative method for the coordinated recycling of resources by producing hydrogen from urea-containing wastewater, which effectively solves the above-mentioned problems. First, this method organically combines wastewater treatment with hydrogen production to achieve efficient utilization of resources. The use of an electrocatalytic urea oxidation system avoids the shortcomings of traditional biological and chemical methods, has high treatment efficiency, and does not require a large amount of chemical agents. Secondly, the present invention gives priority to the use of renewable energy for power generation, such as solar photovoltaic or wind power generation, which not only reduces carbon emissions, but also provides support for peak and frequency regulation of the power grid. The introduction of a membrane distillation system realizes the recycling of water resources and improves the resource utilization efficiency of the overall system.

[0065] Another advantage of the present invention is its highly integrated intelligent control system. By monitoring and automatically adjusting the operating parameters all the time, the system is ensured to operate at the optimal efficiency point. This holistic and coordinated approach not only improves the stability and reliability of the system, but also greatly improves the overall economic benefits. Through the synergy of wastewater treatment, hydrogen production and water resource recycling, the present invention creates significant economic value while achieving long-term sustainable operation.

[0066] In summary, the scheme of the present invention has significant advantages over the prior art in terms of treatment efficiency, resource utilization, energy consumption, and environmental friendliness. It not only achieves harmless treatment of urea-containing wastewater, but also achieves efficient recycling of resources, especially the generation of hydrogen energy. This collaborative treatment method greatly improves the economic and environmental benefits of the entire system, provides a new and efficient solution for the treatment of urea-containing wastewater, and has important practical application value and broad development prospects.

[0067] Those skilled in the art can understand that the above-mentioned embodiments are specific examples for implementing the present application, and in practical applications, various changes can be made to them in form and detail without departing from the spirit and scope of the present application. Any person skilled in the art can make their own changes and modifications without departing from the spirit and scope of the present application, so the scope of protection of the present application shall be based on the scope defined in the claims.

Claims

1. A urea-containing wastewater hydrogen production and resource recycling system, characterized in that: The system includes a storage bin, a urea-assisted water electrolysis system, a membrane distillation system and a condensed water tank which are connected in sequence; The storage bin is also connected to the membrane distillation system, and the urea-assisted water electrolysis system is connected to a green electricity generation system, which is used to provide electrical energy to the system; the condensed water tank is also connected to the membrane distillation system again through a refrigeration device; The storage bin is used to connect to a urea wastewater source, perform alkali treatment and heating treatment on the urea-containing wastewater generated by pretreatment of the urea wastewater source, and transport the treated urea-containing wastewater to the urea-assisted water electrolysis system; The urea-assisted water electrolysis system is used to electrolyze the urea-containing wastewater, and the generated hydrogen is used for recovery, other gases are directly discharged, and the effluent is transported to the membrane distillation system; The membrane distillation system is used to concentrate the urea-containing wastewater, pump out the generated hot end concentrate or transport it to the storage bin again for the next round of circulation treatment, and condense the generated steam into condensed water and transport it to the condensed water tank; The condensed water tank is used to store condensed water, or to transport the condensed water to a refrigeration device to generate cooling water as supplementary water and transport it to the membrane distillation system as supplementary electrolyte.

2. The urea-containing wastewater hydrogen production and resource recycling system according to claim 1 is characterized in that: The storage bin comprises a bin body, a dosing device is arranged on the top of the bin body, a heating device is arranged on the bottom, and a pH monitoring probe is arranged on the inner wall of the bin body; The dosing device is used to add alkali to the urea-containing wastewater; The heating device is used to heat the urea-containing wastewater; The pH monitoring probe is used to monitor the pH value of the urea-containing wastewater.

3. The urea-containing wastewater hydrogen production and resource recycling system according to claim 1 is characterized in that: The membrane distillation system comprises a cold end and a hot end, wherein the cold end and the hot end are separated by a hydrophobic microporous membrane, the cold end is used to pump cooling water, and the hot end is used to receive urea-containing wastewater treated by the urea-assisted water electrolysis system, and cooperate with the cold end to concentrate the urea-containing wastewater; Wherein, the material of the hydrophobic microporous membrane is polytetrafluoroethylene.

4. The urea-containing wastewater hydrogen production and resource recycling system according to claim 1 is characterized in that: A liquid level monitoring probe is provided in the urea-assisted water electrolysis system, and a liquid level monitoring probe is provided in the condensed water tank.

5. The urea-containing wastewater hydrogen production and resource recycling system according to claim 1 is characterized in that: A pump is provided between the urea-assisted water electrolysis system and the membrane distillation system, and a pump is also provided between the condensed water tank and the refrigeration device.

6. A method for synergistic resource recycling by producing hydrogen from urea-containing wastewater, characterized in that: The method is applied to the system as claimed in any one of claims 1 to 5; the method comprises the following steps: Wastewater containing urea enters the storage silo; The urea-containing wastewater is treated with alkali and heat, and the effluent is transported to the urea-assisted water electrolysis system; The urea-containing wastewater is subjected to electrolysis treatment, and the generated hydrogen is used for recovery, other gases are directly discharged, and the effluent is transported to a membrane distillation system; The urea-containing wastewater is concentrated, and the generated hot end concentrated liquid is pumped out or transported to the storage bin again for the next round of circulation treatment, and the generated condensed water is transported to the condensed water tank; The condensed water is stored or sent to a refrigeration device to generate cooling water as make-up water and then sent to a membrane distillation system as a supplementary electrolyte.

7. The method for synergistic resource recycling of urea-containing wastewater to produce hydrogen according to claim 6, characterized in that: The method specifically comprises the following steps: The urea-containing wastewater enters the storage bin after pretreatment such as flocculation and filtration; Monitor the pH of urea-containing wastewater in the storage bin, start the dosing device and start the heating device; The urea-containing wastewater in the storage bin is pumped into the anode end of the electrolyzer in the urea-assisted water electrolysis system, and the cathode end is potassium hydroxide solution. The anode and cathode are separated by an anion exchange membrane. After applying voltage to the electrolyzer, high-purity hydrogen is recovered at the cathode end, and the gas generated at the anode is directly discharged. The water at the end of the anode end directly enters the hot end of the membrane distillation system. Cooling water for recycling is pumped into the cold end; due to the temperature difference between the hot and cold end feed liquids, water in the form of water vapor passes through the hydrophobic microporous membrane of polytetrafluoroethylene from the hot end to the cold end for condensation, and the hot end feed liquid is concentrated into hot end concentrated liquid; the hot end concentrated liquid carries almost all the potassium hydroxide and urea in the hot end feed liquid, and the hot end concentrated liquid is pumped out of the membrane distillation system or directly enters the storage bin for the next round of circulation treatment; The steam generated in the membrane distillation system is directly taken into the cooling water for condensation and can continue to be used as cooling water, or as make-up water to supplement the cathode electrolyte of urea-assisted water electrolysis, or be used for other purposes after simple treatment.

8. The method for synergistic resource recycling of urea-containing wastewater to produce hydrogen according to claim 7, characterized in that: The steps of starting the dosing device and starting the heating device specifically include: starting the dosing device to add potassium hydroxide until the pH of the urea-containing wastewater reaches 14; starting the heating device to control the temperature of the urea-containing wastewater at 70°C.

9. The method for synergistic resource recycling of urea-containing wastewater hydrogen production according to claim 7, characterized in that: The temperature of the cooling water is 10-15°C.

10. The method for synergistic resource recycling of urea-containing wastewater to produce hydrogen according to claim 6, characterized in that: When the urea concentration of the urea-containing wastewater is 20 g / L, the hydrogen production is 0.77 Nm 3 / h.

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