Device for resource treatment of iron phosphate wastewater through cooperation of spiral carbon felt and magnesium metal plate

Abstract

The invention discloses a device for resource treatment of iron phosphate wastewater through cooperation of a spiral carbon felt and a magnesium metal plate, the device comprises an electrolytic reaction device, the electrolytic reaction device comprises an iron phosphate wastewater container and a spiral device arranged in the iron phosphate wastewater container, and the spiral device comprises a spiral device and a modified carbon felt wound on the spiral device; the modified carbon felt is wound upwards clockwise around the spiral structure of the spiral device from the bottom end of the outer wall of the spiral device, and the modified carbon felt is fixed at equal intervals in the winding direction through a fixator and is wound to the top end of the spiral device; a magnesium metal plate is arranged in an inner hole of the spiral device; the spiral device is provided with a precipitator corresponding to the bottom of the magnesium metal plate; the modified carbon felt is used as the cathode to replace a traditional titanium plate or graphite plate, the waste plastic and the waste carbon felt are made into the spiral device in a spiral shape through the microwave-assisted cracking technology, the modified carbon felt and the spiral device form the spiral device, the design cost is further reduced, struvite is efficiently recycled, and the recycling cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental engineering wastewater treatment, and in particular relates to a device for resource-based treatment of iron phosphate wastewater by using spiral carbon felt in conjunction with a magnesium metal plate. Background Art

[0002] Against the backdrop of global climate change, exhaustion of traditional energy, and orderly advancement of carbon peak and carbon neutrality, new energy sources based on lithium-ion batteries have entered a stage of rapid development. Lithium-ion batteries have become the fastest-growing new energy batteries due to their high energy density, high cell voltage, no memory, and long cycle life. Iron phosphate is the precursor of lithium iron phosphate in lithium batteries, and the iron phosphate synthesis process will produce a large amount of high-nitrogen, high-phosphorus, and high-salt iron phosphate wastewater, which poses a great threat to the environment and huge pressure on water treatment. Since iron phosphate wastewater contains high concentrations of phosphate and ammonia nitrogen, the treatment of iron phosphate wastewater is currently concentrated on a variety of traditional processes such as neutralization precipitation, MVR evaporation, and membrane separation technology. Among them, chemical precipitation technology has obvious advantages because it generates slow-release fertilizer struvite while removing phosphorus and nitrogen pollutants. The struvite generated is used as a slow-release fertilizer in the agricultural field, thereby reducing the cost of wastewater treatment. Nutrients such as nitrogen, phosphorus and iron in iron phosphate wastewater have the dual properties of environmental pollution and potential energy carriers. The use of high-efficiency and low-consumption treatment technology to convert and recycle them is an effective response to climate change and one of the important measures to achieve carbon neutrality. Recovering phosphorus from waste streams is seen as an important means to delay the depletion of phosphorus reserves worldwide. Therefore, in recent years, a large number of scholars have been committed to the scientific and environmentally friendly treatment of iron phosphate wastewater in order to seek sustainable development of resources. However, current research has not been able to achieve industrial application and production, mainly because the recovery efficiency of struvite is low and the plate materials such as magnesium metal plates and titanium plates used in the recovery process are expensive, making it impossible to achieve economic and sustainable development.

[0003] With the progress and development of the times, solar energy has emerged and been spread and applied. As the most promising renewable energy in the 21st century, solar energy is only limited by conversion costs and time intervals, and has the advantages of long life, modularization, low maintenance, low noise, and good matching with loads. It can reduce the pollution caused by the combustion of mineral energy to the environment and reduce carbon emissions. The solar photovoltaic power generation system uses the electricity generated by photovoltaic modules to charge the battery and can directly supply power to the load under sunshine. If there is insufficient sunlight or at night, the battery supplies power to the DC load under the operation of the controller. In a system with AC load, an inverter is required to convert AC into DC. my country has a vast territory, and most of it is in low and medium latitudes, with abundant solar energy reserves. Using solar energy to drive the water treatment process is a potential sustainable solution to the problem of water shortage and resource waste. Therefore, the application of solar energy in the field of water treatment is not only a feasibility study in line with the development of the times, but also a measure to further realize the industrial treatment of iron phosphate wastewater, recycle struvite, and apply it to the agricultural market.

[0004] At present, there have been many studies on carbon felt modification, in order to realize the application of carbon felt as cathode in various fields, improve efficiency and reduce costs. Through electro-Fenton technology modification, active free radicals with strong oxidizing properties are generated through electrochemical reaction and introduced into the surface of carbon felt, thereby catalyzing electrode reaction and reducing electrochemical polarization loss, which can effectively improve the service life and processing efficiency of carbon felt. How to further improve the service life of modified carbon felt and improve the efficiency of resource recycling requires further improvement and design. Summary of the invention

[0005] The present invention provides a device for resource-based treatment of iron phosphate wastewater by using spiral carbon felt and magnesium metal plate. Modified carbon felt is used as a cathode to replace traditional titanium plates or graphite plates. The modified carbon felt is combined with a spiralizer. Waste plastics and waste carbon felt are used to make a spiralizer through microwave-assisted cracking technology, which further reduces design costs, achieves efficient recovery of struvite and reduces recovery costs.

[0006] To solve the above problems, the technical solution provided by the present invention is as follows:

[0007] The embodiment of the present invention provides a device for resource-based treatment of iron phosphate wastewater by using spiral carbon felt in conjunction with a magnesium metal plate, comprising an electrolytic reaction device and a solar power supply system, wherein the electrolytic reaction device comprises an iron phosphate wastewater container and a spiral device placed in the iron phosphate wastewater container, wherein the spiral device comprises a spiral and a modified carbon felt wound on the spiral, and the modified carbon felt starts from the bottom end of the outer wall of the spiral and is wound clockwise around the spiral structure of the spiral, and the modified carbon felt is fixed at equal distances along the winding direction by a fixing device and is wound to the top of the spiral; the inner hole of the spiral is provided with a magnesium metal plate, and the spiral device is provided with a precipitator corresponding to the bottom of the magnesium metal plate;

[0008] The solar power supply system includes a photovoltaic panel, the photovoltaic panel is connected to a conversion controller, the conversion controller is connected to a battery, the conversion controller is connected to a DC power supply through an inverter, the positive pole of the DC power supply is electrically connected to the magnesium metal plate, and the negative pole of the DC power supply is electrically connected to the modified carbon felt.

[0009] According to an optional embodiment of the present invention, the fixture is a conical structure, the bottom diameter of the conical structure is 1 to 5 mm, and the material of the fixture is solid wood.

[0010] According to an optional embodiment of the present invention, the outer wall of the screw is a porous structure, and the fixer fixes the modified carbon felt to the screw through a plurality of porous structures.

[0011] According to an optional embodiment of the present invention, the ferric phosphate wastewater container is connected to an aeration device, and the aeration device transports oxygen to the electrolyte in the ferric phosphate wastewater container at a preset aeration rate. The ferric phosphate wastewater is used as the electrolyte, and the modified carbon felt is easily adsorbed by the aeration gas through its porous structure, thereby accelerating the rate of the redox reaction, thereby accelerating the formation of struvite.

[0012] According to an optional embodiment of the present invention, the area of ​​the magnesium metal plate is 25 to 100 cm 2 , the ratio of the solution volume of the electrolyte to the area of ​​the magnesium metal plate is between 10 and 20.

[0013] According to an optional embodiment of the present invention, the material of the spiral device is waste plastic and waste carbon felt, the modified carbon felt is modified by electro-Fenton technology, and the aeration device is an aeration oxygen pump.

[0014] According to an optional embodiment of the present invention, the inner hole wall of the spiralizer is a smooth structure, and the smooth structure prevents the struvite generated on the surface of the magnesium metal plate from being adsorbed by the modified carbon felt.

[0015] Compared with the prior art, the embodiment of the present invention provides a device for resource-based treatment of iron phosphate wastewater by using spiral carbon felt in conjunction with magnesium metal plate, which has the following beneficial effects:

[0016] (1) The device uses cheap and easily available modified carbon felt to replace traditional cathode materials such as titanium plates or graphite plates, and conducts modification research on carbon felt to promote the corrosion reaction of magnesium metal plates; secondly, the spiral device is made of waste carbon felt and waste plastics through microwave-assisted pyrolysis technology to form a solid spiral device, which completely realizes green production and reduces the cost of struvite recovery; and the structural characteristics of the spiral device can realize the separate collection of struvite, preventing struvite from being adsorbed by modified carbon felt and causing unnecessary losses; the spiral modified carbon felt can be used more times, and the spiral structure helps to extend the service life of the modified carbon felt.

[0017] (2) The present invention proposes a spiral device made of a mixture of waste plastics and waste carbon felt, which not only allows electrons to enter and exit freely, but also provides attachment sites for oxygen and electrons, promotes electron transfer in the device, and can alleviate the pressure of plastic waste accumulation in the environment in the form of waste materials, greatly reducing the cost of struvite recovery, thereby achieving the purpose of protecting the environment and obtaining energy.

[0018] (3) The present invention provides a method of replacing traditional energy resources with green new energy, using solar photovoltaic panels to generate electricity to provide all power for the reaction device, thereby reducing the cost of wastewater treatment and promoting the green, low-carbon and high-quality development of the new energy industry.

[0019] (4) The present invention utilizes modified carbon felt, aeration and stirring to promote the corrosion reaction of magnesium metal plates. It is easy to operate, has a simple preparation method, and requires low cost, thereby realizing low-cost treatment of iron phosphate wastewater and recovery of struvite. The economic practicality of the method is further improved by studying the repeated use of modified carbon felt. The nitrogen and phosphorus in the iron phosphate waste liquid are recycled, and the nitrogen and phosphorus recovery rate is as high as more than 95%, and the space-time yield of the generated struvite is extremely high. At the same time, it can save electricity consumption and cost, thereby greatly reducing the cost of resource management of iron phosphate waste liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A schematic diagram of the structure of a device for resource-based treatment of iron phosphate wastewater using spiral carbon felt and magnesium metal plates provided in an embodiment of the present application.

[0022] Figure 2 A three-dimensional schematic diagram of a spiral device provided in an embodiment of the present application.

[0023] Figure 3 A cross-sectional schematic diagram of a spiral device provided in an embodiment of the present application.

[0024] Figure 4 A top view of a spiral device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0026] like Figure 1 , Figure 2 , Figure 3 and Figure 4 As shown, an embodiment of the present invention provides a device for resource-based treatment of iron phosphate wastewater by using spiral carbon felt in conjunction with magnesium metal plate, including an electrolytic reaction device and a solar power supply system. The electrolytic reaction device includes an iron phosphate wastewater container 1 and a spiral device placed in the iron phosphate wastewater container 1. The spiral device includes a spiral 2 and a modified carbon felt 3 wound on the spiral 2, and the modified carbon felt 3 starts from the bottom end of the outer wall of the spiral 1, and is wound clockwise around the spiral structure of the spiral 2, and the modified carbon felt 3 is fixed at equal distances along the winding direction with a fixer, and is wound to the top of the spiral 2. The inner hole of the spiral device is provided with a magnesium metal plate 4, and the spiral device is provided with a precipitator 4-1 at the bottom of the magnesium metal plate 4 corresponding to the spiral device. The precipitator 4-1 can directly collect the struvite generated by the reaction, while preventing the struvite from adhering to the surface of the modified carbon felt and affecting the electrochemical properties of the modified carbon felt.

[0027] The solar power supply system includes a photovoltaic panel 6, the photovoltaic panel 6 is connected to a conversion controller 7, the conversion controller 7 is connected to a battery 8, the conversion controller 7 is connected to a DC power supply 10 through an inverter 9, the positive electrode of the DC power supply 10 is electrically connected to the magnesium metal plate 4, and the negative electrode of the DC power supply 10 is electrically connected to the modified carbon felt 3. The output current of the DC power supply 10 is 200-1000mA.

[0028] like Figure 2 , Figure 3 and Figure 4 As shown, the fixture in this embodiment is a conical structure, the bottom diameter of the conical structure is 1-5 mm, and the material of the fixture is solid wood. The outer wall of the spiral 2 is a porous structure, and the fixture fixes the modified carbon felt 3 to the spiral 2 through the porous structure.

[0029] The iron phosphate wastewater container 1 is connected to an aeration device 5, which delivers oxygen to the electrolyte in the iron phosphate wastewater container 1 at a preset aeration rate. The iron phosphate wastewater is used as the electrolyte, and the modified carbon felt 3 easily absorbs the aerated gas through the multiple pore structures on the outer wall of the spiral device 2, thereby accelerating the rate of the redox reaction, thereby accelerating the formation of struvite. The aeration device 5 is preferably an aeration oxygen pump.

[0030] The area of ​​the magnesium metal plate 4 is 25 to 100 cm 2 The ratio of the volume of the electrolyte to the area of ​​the magnesium metal plate 4 is between 10 and 20. The material of the spiral 2 is waste plastic and waste carbon felt, and the modified carbon felt 3 is carbon felt modified by electro-Fenton technology. The inner hole wall of the spiral 2 is a smooth structure, which is close to the characteristics of plastic products. The smooth structure prevents the struvite generated on the surface of the magnesium metal plate 4 from being adsorbed by the modified carbon felt 3.

[0031] When the spiral device is in operation, the magnesium metal plate 4 is placed in the inner hole of the spiral device, and the magnesium metal plate 4 is directly connected to the positive electrode of the DC power supply 10. The modified carbon felt 3 starts from the lower end of the outer wall of the spiral device, and is wound up clockwise around the spiral structure. The modified carbon felt 3 is fixed at equal distances along the winding direction with a fixture, and is wound to the top of the spiral structure and connected to the negative electrode of the DC power supply 10. When the spiral device is in operation, the reaction conditions need to be controlled. The reaction conditions are to provide an aeration rate of 4 to 8 L / min, a stable current of 200 to 1000 mA, a stirring rate of 200 to 800 rpm / min, a reaction time of 0.5 to 2 hours, and a magnesium metal plate area of ​​25 to 100 cm 2 When the ratio of solution volume to plate area is between 10 and 20, the phosphoric acid removal rate can reach more than 95%.

[0032] The modified carbon felt 3 is a carbon felt modified by electro-Fenton technology. The electro-Fenton technology is used to introduce active free radicals with strong oxidizing properties to the surface of the carbon felt, thereby catalyzing the electrode reaction on the carbon felt, making the anode reaction, i.e., the corrosion of the magnesium metal plate 4, more efficient, and reducing the electrochemical polarization loss. The modified carbon felt can be reused 10 to 50 times, and the multiple reuse of the modified carbon felt further reduces the treatment cost of iron phosphate wastewater.

[0033] The present invention designs and manufactures a low-cost spiralizer, which uses cheap and easily available waste plastics and waste carbon felt to form a solid spiralizer through microwave-assisted pyrolysis technology, thereby completely realizing green production, achieving the purpose of protecting the environment and obtaining energy, and promoting the green, low-carbon and high-quality development of the industry; the present invention designs and manufactures a spiralizer with a special structure, which not only allows electrons to enter and exit freely, but also provides attachment sites for oxygen and electrons, promotes electron transfer in the device, and can also collect the generated struvite separately to avoid adsorption by modified carbon felt and unnecessary loss of struvite.

[0034] Combining solar power generation with wastewater resource treatment, photovoltaic panels can replace traditional energy sources. Through DC control, stable current can be delivered to the reaction device, which greatly reduces the cost of iron phosphate wastewater treatment and promotes the further development of low-carbon and environmentally friendly new energy industry.

[0035] The chemical reaction principle of the electrolytic reaction device of the present invention is as follows: the modified carbon felt is attached to the outside of the spiral device, the output current is controlled by a DC power supply, and a stable current is directly provided to the electrolytic reaction device through a solar power supply device. A magnesium metal plate is placed in the inner hole of the spiral device to prevent the modified carbon felt from adsorbing struvite crystals due to its porous material characteristics and reducing the recovery rate of struvite. A precipitator is provided at the bottom of the spiral device to directly collect the struvite generated by the reaction and prevent the struvite from adhering to the surface of the modified carbon felt and affecting the electrochemical properties of the modified carbon felt. The negative electrode connection site of the DC power supply is the modified carbon felt at the top of the spiral, and the positive electrode is connected to the top of the magnesium metal plate. During the experiment, the aeration device transports oxygen to the electrolyte at a certain aeration rate, and iron phosphate wastewater is used as the electrolyte. The modified carbon felt is easy to adsorb aerated gas due to its porous structure, thereby accelerating the rate of the redox reaction, thereby accelerating the formation of struvite. The chemical reaction equation is as follows.

[0036] Cathode partial reaction: 2H2O+2e - →H2+2OH - (1);

[0037] Anode partial reaction: Mg→Mg 2+ +2e - (2);

[0038] Overall reaction: Mg 2+ +NH4 + +HPO4 2- +6H2O→MgNH4PO4·6H2O↓+H + (3).

[0039] In summary, although the present invention has been disclosed as above in terms of preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A device for resource treatment of iron phosphate wastewater by using spiral carbon felt and magnesium metal plate, characterized in that: It comprises an electrolytic reaction device and a solar power supply system, wherein the electrolytic reaction device comprises an iron phosphate wastewater container and a spiral device placed in the iron phosphate wastewater container, wherein the spiral device comprises a spiral and a modified carbon felt wound on the spiral, and the modified carbon felt starts from the bottom end of the outer wall of the spiral and is wound up clockwise around the spiral structure of the spiral, and the modified carbon felt is fixed at equal distances along the winding direction by a fixing device and is wound to the top of the spiral; a magnesium metal plate is arranged at the inner hole of the spiral device, and a precipitator is arranged at the bottom of the spiral device corresponding to the magnesium metal plate; The solar power supply system includes a photovoltaic panel, the photovoltaic panel is connected to a conversion controller, the conversion controller is connected to a battery, the conversion controller is connected to a DC power supply through an inverter, the positive pole of the DC power supply is electrically connected to the magnesium metal plate, and the negative pole of the DC power supply is electrically connected to the modified carbon felt.

2. The device for treating iron phosphate wastewater by using spiral carbon felt and magnesium metal plate as resources according to claim 1 is characterized in that: The fixer is a conical structure, the bottom diameter of the conical structure is 1-5 mm, and the material of the fixer is solid wood.

3. The device for treating iron phosphate wastewater by using spiral carbon felt and magnesium metal plate as resources according to claim 2 is characterized in that: The outer wall of the screw is a porous structure, and the fixer fixes the modified carbon felt to the screw through a plurality of porous structures.

4. The device for treating iron phosphate wastewater by using spiral carbon felt and magnesium metal plate as resources according to claim 3 is characterized in that: The ferric phosphate wastewater container is connected to an aeration device, which transports oxygen to the electrolyte in the ferric phosphate wastewater container at a preset aeration rate. The ferric phosphate wastewater is used as the electrolyte. The modified carbon felt is easy to adsorb the aerated gas through its porous structure, thereby accelerating the rate of the redox reaction, thereby accelerating the formation of struvite.

5. The device for treating iron phosphate wastewater by using spiral carbon felt in conjunction with magnesium metal plate according to claim 4 is characterized in that: The area of ​​the magnesium metal plate is 25 to 100 cm 2 , the ratio of the solution volume of the electrolyte to the area of ​​the magnesium metal plate is between 10 and 20.

6. The device for treating iron phosphate wastewater by using spiral carbon felt in conjunction with magnesium metal plate according to claim 4 is characterized in that: The material of the spiral device is waste plastic and waste carbon felt, the modified carbon felt is carbon felt modified by electro-Fenton technology, and the aeration device is an aeration oxygen pump.

7. The device for treating iron phosphate wastewater by using spiral carbon felt in conjunction with magnesium metal plate according to claim 1 is characterized in that: The inner hole wall of the spiralizer is a smooth structure, and the smooth structure prevents the struvite generated on the surface of the magnesium metal plate from being adsorbed by the modified carbon felt.

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