An electrochemical seawater aquaculture tailwater treatment device

Abstract

The present application provides an electrochemical seawater aquaculture tailwater treatment device, including an anode tank, a cathode tank and a power supply; the anode in the anode tank and the cathode in the cathode tank are respectively connected to the power supply; the cathode tank is used to remove nitrate nitrogen and nitrite nitrogen in the aquaculture tailwater through a reduction reaction, and the anode tank is used to remove organic pollutants and ammonia nitrogen in the aquaculture tailwater through an oxidation reaction; a cation exchange membrane is provided between the anode tank and the cathode tank, and the cation exchange membrane is used to separate the anode and cathode solutions, and transfer the target monovalent cations generated by the aquaculture tailwater in the anode tank from the anode tank to the cathode tank, while preventing the anions generated in the anode tank from entering the cathode tank. By adding a cation exchange membrane between the anode and cathode electrodes, the anode and cathode are separated, the advantages of the anode and cathode are maximized, and the interference of the anode and cathode electrodes to reduce the reaction efficiency is avoided. Through the electrochemical cathode reaction zone and the anode reaction zone, the total nitrogen is effectively removed, which plays a role in degrading organic pollutants and sterilizing.

Description

Technical Field

[0001] The present application relates to the field of wastewater treatment, and in particular to an electrochemical seawater aquaculture tailwater treatment device. Background Art

[0002] The nitrogen-containing inorganic pollutants in aquaculture tailwater mainly include ammonia nitrogen, nitrite and nitrate. When the concentration of ammonia nitrogen and nitrite exceeds the standard, it will cause disease outbreaks in aquaculture organisms, poison aquaculture organisms, and affect the growth and yield of aquaculture individuals. Studies have shown that the tolerance concentration of total ammonia nitrogen and nitrite for aquaculture individuals is less than 0.5 mg / L. The discharge of pollutants from the marine aquaculture industry will not only cause pollution to the aquaculture water itself, but also cause serious water environment pollution when the aquaculture tailwater is discharged into natural water bodies. Due to the high salinity of seawater, it is difficult to completely treat it with conventional biological methods.

[0003] Electrochemical technology is a new water treatment method that has emerged in recent years. It mainly uses the high potential of the anode and its catalytic activity to directly oxidize pollutants in the water, or produces hydroxyl radicals (·OH), chlorine and other strong oxidants to indirectly oxidize and degrade pollutants in the water. Electrochemical technology can convert ammonia nitrogen into nitrogen and nitrite into nitrate through direct or indirect oxidation reactions at the anode, and at the same time, convert nitrite and nitrate into nitrogen through cathode reduction.

[0004] At present, there are more studies on the application of electrochemical technology to denitrification of industrial wastewater, but fewer studies on the denitrification of aquaculture tailwater. In addition, the existing methods of applying electrochemical technology to denitrification of aquaculture tailwater have low efficiency in removing total nitrogen from wastewater. Utility Model Content

[0005] In view of the above problems, the present application is proposed to provide an electrochemical seawater aquaculture tailwater treatment device that overcomes the above problems or at least partially solves the above problems, comprising:

[0006] An electrochemical seawater aquaculture tail water treatment device is used to treat seawater aquaculture tail water by electrochemical technology, comprising an anode tank, a cathode tank and a power supply;

[0007] The anode in the anode tank and the cathode in the cathode tank are respectively connected to the power supply; the cathode tank is used to remove nitrate nitrogen and nitrite nitrogen in the aquaculture tail water by reduction reaction, and the anode tank is used to remove organic pollutants and ammonia nitrogen in the aquaculture tail water by oxidation reaction;

[0008] A cation exchange membrane is provided between the anode tank and the cathode tank, and the cation exchange membrane is used to transfer the target monovalent cations generated by the aquaculture tail water in the anode tank from the anode tank to the cathode tank, while preventing the anions generated in the anode tank from entering the cathode tank.

[0009] Preferably, a height difference is provided between the cathode tank and the anode tank, and an overflow weir tank is provided at the water outlet of the cathode tank.

[0010] Preferably, the overflow weir water tank comprises an overflow plate and an overflow weir outlet pipe, and the overflow plate is arranged at the outlet of the cathode tank.

[0011] Preferably, the anode in the anode cell is a chlorine evolution electrode.

[0012] Preferably, the cathode in the cathode cell is a copper plate, a graphite plate, a stainless steel plate, an iron plate, a nickel plate, a titanium plate or a metal-doped plate.

[0013] Preferably, a cathode water inlet is provided at the bottom of the cathode tank.

[0014] Preferably, an anode water inlet is provided at the bottom of the anode tank, and a water outlet is provided at the top of the anode tank.

[0015] Preferably, inner walls of the cathode tank and the anode tank are both provided with a rubber layer.

[0016] Preferably, the cell voltage between the cathode cell and the anode cell is 1.35V to 20.0V.

[0017] Preferably, the power supply is a direct current power supply or a pulse power supply.

[0018] This application has the following advantages:

[0019] In the embodiment of the present application, relative to the problem of low removal efficiency of the existing electrochemical technology applied to the denitrification of aquaculture tail water, the present application provides a solution to isolate the two poles through an anode ion exchange membrane, specifically: including an anode tank, a cathode tank and a power supply; the anode in the anode tank and the cathode in the cathode tank are respectively connected to the power supply; the cathode tank is used to remove nitrate nitrogen and nitrite nitrogen in the aquaculture tail water by reduction reaction, and the anode tank is used to remove organic pollutants and ammonia nitrogen in the aquaculture tail water by oxidation reaction; a cation exchange membrane is provided between the anode tank and the cathode tank, and the cation exchange membrane is used to transfer the target monovalent cations generated in the aquaculture tail water in the anode tank from the anode tank to the cathode tank, while preventing the anions generated in the anode tank from entering the cathode tank. By adding a cation exchange membrane between the anode and cathode electrodes to separate the anode and cathode, the advantages of the anode and cathode are maximized, and the problem of interference between the anode and cathode in conventional electrochemical reactions to reduce the reaction efficiency is solved. The total nitrogen is also effectively removed by continuously passing the seawater aquaculture tail water through the electrochemical cathode reaction zone and the anode reaction zone, while playing the role of degrading organic pollutants and sterilizing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for use in the description of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0021] Figure 1 This is a schematic structural diagram of an electrochemical seawater aquaculture tailwater treatment device provided in one embodiment of the present application;

[0022] Figure 2 It is a stereoscopic diagram of an electrochemical seawater aquaculture tailwater treatment device provided in one embodiment of the present application.

[0023] The reference numerals in the drawings of the specification are as follows:

[0024] 1. Cathode water inlet; 2. Cathode; 3. Overflow weir trough; 4. Overflow plate; 5. Overflow weir outlet pipe; 6. Power supply; 7. Anode; 8. Water outlet; 9. Anode water inlet; 10. Cation exchange membrane. DETAILED DESCRIPTION

[0025] In order to make the objects, features and advantages of the present application more obvious and understandable, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are 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 ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0026] The inventors have found through analysis of the prior art that the prior art applies electrochemical technology to the treatment of total nitrogen wastewater. Since the anode and cathode are in the same reaction zone, the anode will produce oxidizing substances and the cathode will produce reducing substances. To degrade total nitrogen, it is necessary to reduce nitrate nitrogen and oxidize ammonia nitrogen. When the two areas of the anode and cathode are mixed, the oxidizing substances and the reducing substances will react, so they are not used to degrade total nitrogen, reducing the removal effect. Among them, the oxidizing substances are mainly hypochlorite, and the reducing substances are reduced hydrogen, etc. They interfere with each other and affect the removal efficiency of total nitrogen in wastewater. The utility model uses an anode ion exchange membrane to isolate the two electrodes, so that the oxidizing substances and the reducing substances cannot contact and react, thereby maximizing the removal effect of the anode and cathode on the total nitrogen in wastewater.

[0027] Reference Figure 1 and Figure 2, shows an electrochemical seawater aquaculture tail water treatment device provided in an embodiment of the present application, which is used to treat seawater aquaculture tail water by electrochemical technology, including an anode tank, a cathode tank and a power supply; the anode 7 in the anode tank and the cathode 2 in the cathode tank are respectively connected to the power supply 6; the cathode tank is used to remove nitrate nitrogen and nitrite nitrogen in the aquaculture tail water by reduction reaction, and the anode tank is used to remove organic pollutants and ammonia nitrogen in the aquaculture tail water by oxidation reaction; a cation exchange membrane 10 is provided between the anode tank and the cathode tank, and the cation exchange membrane 10 is used to transfer the target monovalent cations generated in the aquaculture tail water in the anode tank from the anode tank to the cathode tank, while preventing the anions generated in the anode tank from entering the cathode tank.

[0028] In the embodiment of the present application, relative to the problem that the removal efficiency of the existing electrochemical technology applied to the denitrification of aquaculture tail water is not high, the present application provides a solution to isolate the two poles through an anode ion exchange membrane, specifically: including an anode tank, a cathode tank and a power supply; the anode 7 in the anode tank and the cathode 2 in the cathode tank are respectively connected to the power supply 6; the cathode tank is used to remove nitrate nitrogen and nitrite nitrogen in the aquaculture tail water by reduction reaction, and the anode tank is used to remove organic pollutants and ammonia nitrogen in the aquaculture tail water by oxidation reaction; a cation exchange membrane 10 is provided between the anode tank and the cathode tank, and the cation exchange membrane 10 is used to transfer the target monovalent cations generated in the aquaculture tail water in the anode tank from the anode tank to the cathode tank, while preventing the anions generated in the anode tank from entering the cathode tank. By adding a cation exchange membrane between the positive and negative electrodes to separate the positive and negative electrodes, the advantages of the positive and negative electrodes are maximized, and the problem of interference between the positive and negative electrodes and the reduction of reaction efficiency in conventional electrochemical reactions is solved. The total nitrogen is also effectively removed by continuously passing the seawater aquaculture tail water through the electrochemical cathode reaction zone and the anode reaction zone, while playing the role of degrading organic pollutants and sterilizing.

[0029] Next, an electrochemical seawater aquaculture tailwater treatment device in each exemplary embodiment of the present application will be further described.

[0030] It should be noted that high salt and large fluctuations in water volume are the water quality characteristics of marine aquaculture tail water. Conventional biological treatment methods have limited treatment effects. This embodiment uses an electrochemical method for the treatment of marine aquaculture tail water, and a set of devices is made. In order to solve the problem of interference between the cathode and cathode in conventional electrochemical reactions to reduce the reaction rate, a cation exchange membrane 10 is added between the cathode and cathode reaction tanks. The function of the cation exchange membrane 10 is mainly to separate the cathode and cathode solutions, but it can pass current (cations can pass to form current). Anions and water cannot pass. Anode oxidation of ammonia nitrogen, what works is chlorine and hypochlorous acid, which decomposes into hypochlorite in water, which is an anion and will only be at the anode. It can effectively avoid reacting with the reduced hydrogen of the cathode. The cation exchange membrane 10 separates the reaction area without hindering ion transmission. The cation exchange membrane 10 transfers the target monovalent cations from the anode tank to the cathode tank, while preventing the additional anions generated by the anode tank from entering the cathode tank, wherein the target monovalent cations are monovalent cations such as hydrogen ions, potassium ions or sodium ions.

[0031] In this embodiment, a height difference is provided between the cathode tank and the anode tank, and an overflow weir tank 3 is provided at the water outlet of the cathode tank.

[0032] It should be noted that if the cathode effluent flows directly to the anode, the problem of reaction between the two active substances (hypochlorite and reduced hydrogen) will also occur. By designing the cathode 2 effluent as a waterfall effluent weir, the problem of mixed contact between the anode and cathode liquids caused by continuous flow in the anode and cathode reaction zones can be solved.

[0033] In this embodiment, the overflow weir water tank 3 includes an overflow plate 4 and an overflow weir outlet pipe 5, and the overflow plate 4 is arranged at the outlet of the cathode tank.

[0034] It should be noted that the water outlet of the cathode 2 is separated from the water inlet of the anode 7 by a water drop, and the overflow plate 4 serves to separate the water flow, effectively preventing the problem of the cathode 2 and the anode 7 being connected in series through the inlet and outlet water flows, and making full use of the electrochemical anode and cathode system.

[0035] In this embodiment, the anode 7 in the anode cell is a chlorine evolution electrode.

[0036] It should be noted that the anode 7 is a chlorine evolution electrode (DSA), which mainly plays the role of degrading organic pollutants and ammonia nitrogen.

[0037] In this embodiment, the cathode 2 in the cathode cell is a copper plate, a graphite plate, a stainless steel plate, an iron plate, a nickel plate, a titanium plate or a metal-doped plate.

[0038] It should be noted that the metal-doped plate is a plate doped with two or more metals. The plate can be replaced by a mesh or foam, and a copper mesh plate electrode is preferably used.

[0039] As an example, the reaction volume and plate surface area of ​​the cathode tank and anode tank can be adjusted according to the actual water quality characteristics. For example, if the nitrate nitrogen and nitrite nitrogen in the tail water of marine aquaculture are high and the ammonia nitrogen concentration is low, the number of cathode plates is increased and the volume of the cathode reaction area is adjusted. If the total nitrogen is high, the number of anode reaction plates is increased and the volume of the anode reaction area is adjusted.

[0040] In this embodiment, a cathode water inlet 1 is provided at the bottom of the cathode tank.

[0041] It should be noted that the tail water of marine aquaculture enters the electrochemical cathode tank from the cathode water inlet 1. In the cathode electrode area, nitrate nitrogen and nitrite nitrogen accept electrons from the cathode 2 to undergo a reduction reaction (1) NO3 - +2H + +2e - →NO2 - +H2O;(2)NO2 - +2H2O+3e - →0.5N2+4OH - ; (3) NO3 - +3H2O+5e - →0.5N2↑+4OH - ; (4) NO3 - +6H2O+8e - →NH3+9OH - ; (5) NO2 - +5H2O+6e - →NH3+7OH - Ammonia nitrogen or nitrogen gas is generated. When copper is used as the cathode, ammonia nitrogen is the main reduction product of nitrate nitrogen and nitrite nitrogen.

[0042] In this embodiment, an anode water inlet 9 is provided at the bottom of the anode tank, and a water outlet 8 is provided at the top of the anode tank.

[0043] It should be noted that the cathode effluent of the marine aquaculture tail water is cut off by the overflow drop device, and then flows from the overflow weir outlet pipe 5 to the anode water inlet 9 into the anode tank reaction zone, where the chlorine evolution reaction (1) 2Cl - →Cl2+2e - , then chlorine reacts in water; (2) Cl2+H2O→HOCl+Cl - +H + ; (2) HOCl→ClO - +H + , hypochlorous acid and hypochlorite can react with ammonia nitrogen to produce nitrogen; (3) 3HOCl+2NH4 + →N2↑+3H2O+5H+ +3Cl - ; (4) 3ClO - +2NH4 + →N2↑+3H2O+2H + +3Cl - ; (5) 6OH - +2NH4 + →N2↑+6H2O+2H + +6e - .

[0044] During the entire anode reaction process, organic pollutants in the wastewater will undergo direct oxidation and indirect oxidation. Direct oxidation refers to the process in which pollutants directly lose electrons and are oxidized on the anode 7, and indirect oxidation refers to the process in which organic pollutants are oxidized into simple organic matter by hypochlorite / hypochlorite radicals.

[0045] In this embodiment, the inner walls of the cathode tank and the anode tank are both provided with a rubber layer.

[0046] It should be noted that the outer shell of the electrochemical seawater aquaculture tailwater treatment device is mainly made of carbon steel, and a rubber layer is bonded to the inner wall to prevent wastewater corrosion.

[0047] In this embodiment, the cell voltage between the cathode cell and the anode cell is 1.35V to 20.0V.

[0048] It should be noted that the cell pressure of the electrochemical reactor is set according to the different conductivity of the actual wastewater, and the cell pressure of the cathode cell and the anode cell are generally 1.35V to 20.0V.

[0049] In this embodiment, the power supply 6 is a direct current power supply or a pulse power supply.

[0050] It should be noted that the anode and cathode are respectively connected in parallel to a DC power supply or a pulse power supply, preferably a pulse power supply.

[0051] Example

[0052] The tail water of a coastal aquaculture base was taken as the main research object, and a comparison was made under the same number of electrodes. According to the chlorine evolution potential of seawater, the tank pressure of the device is set to 1.4V. The wastewater first enters the cathode 2 of the utility model device ① through the cathode water inlet 1. At this time, the nitrate nitrogen and nitrite nitrogen in the wastewater undergo direct reduction reaction and indirect reduction reaction to produce nitrogen and ammonia nitrogen. The effluent flows through the overflow plate 4 to form a cut-off flow, and finally enters the reaction anode 7 to undergo chlorine oxidation reaction. Under the same hydraulic retention time, the water inlet to device ②, device ② is a cathode mixing device without an ion membrane, and its number of plates and volume are the same as those of device ①. The effect of the device after the reaction is shown in the following table:

[0053] Table 1 Actual data of seawater aquaculture tailwater treated by electrochemical integrated device

[0054]

[0055] From the results in Table 1, it can be seen that device ① has a better treatment effect on marine aquaculture tail water. The cathode reaction zone has a removal effect of more than 90% on nitrate nitrogen and nitrite nitrogen, 75% of the product is ammonia nitrogen, the anode has a removal rate of nearly 100% for ammonia nitrogen, and the total nitrogen removal rate is 97.1%. However, device ② has a poor removal effect on total nitrogen in marine aquaculture tail water, only 74.8%, and the total nitrogen and COD of the effluent do not meet the discharge requirements of marine aquaculture tail water.

[0056] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0057] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0058] The above is a detailed introduction to an electrochemical seawater aquaculture tailwater treatment device provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for general technicians in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. An electrochemical seawater aquaculture tail water treatment device, used to treat seawater aquaculture tail water by electrochemical technology, characterized in that: It includes an anode tank, a cathode tank and a power supply; The anode in the anode tank and the cathode in the cathode tank are respectively connected to the power supply; the cathode tank is used to remove nitrate nitrogen and nitrite nitrogen in the aquaculture tail water by reduction reaction, and the anode tank is used to remove organic pollutants and ammonia nitrogen in the aquaculture tail water by oxidation reaction; A cation exchange membrane is provided between the anode tank and the cathode tank, and the cation exchange membrane is used to transfer the target monovalent cations generated by the aquaculture tail water in the anode tank from the anode tank to the cathode tank, while preventing the anions generated in the anode tank from entering the cathode tank.

2. The electrochemical seawater aquaculture tailwater treatment device according to claim 1, characterized in that: A height difference is arranged between the cathode tank and the anode tank, and an overflow weir water tank is arranged at the water outlet of the cathode tank.

3. The electrochemical seawater aquaculture tailwater treatment device according to claim 2, characterized in that: The overflow weir water tank comprises an overflow plate and an overflow weir water outlet pipe, and the overflow plate is arranged at the water outlet of the cathode tank.

4. The electrochemical seawater aquaculture tailwater treatment device according to claim 1, characterized in that: The anode in the anode tank is a chlorine evolution electrode.

5. The electrochemical seawater aquaculture tailwater treatment device according to claim 1, characterized in that: The cathode in the cathode tank is a copper plate, a graphite plate, a stainless steel plate, an iron plate, a nickel plate, a titanium plate or a metal-doped plate.

6. The electrochemical seawater aquaculture tailwater treatment device according to claim 1, characterized in that: A cathode water inlet is arranged at the bottom of the cathode tank.

7. The electrochemical seawater aquaculture tailwater treatment device according to claim 6, characterized in that: An anode water inlet is arranged at the bottom of the anode tank, and a water outlet is arranged at the top of the anode tank.

8. The electrochemical seawater aquaculture tailwater treatment device according to claim 1, characterized in that: The inner walls of the cathode tank and the anode tank are both provided with rubber layers.

9. The electrochemical seawater aquaculture tailwater treatment device according to claim 1, characterized in that: The cell voltage between the cathode cell and the anode cell is 1.35V to 20.0V.

10. The electrochemical seawater aquaculture tailwater treatment device according to claim 1, characterized in that: The power supply is a direct current power supply or a pulse power supply.

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