Seawater pretreatment device and method for pretreating seawater by using seawater pretreatment device

Abstract

The invention belongs to the technical field of seawater pretreatment, and discloses a seawater pretreatment device and a method for pretreating seawater by using the seawater pretreatment device, the device comprises an electrochemical reaction device, the electrochemical reaction device comprises a cathode reaction tank, an anode reaction tank and a barrier for separating the cathode reaction tank from the anode reaction tank; a cathode is arranged in the cathode reaction tank, and an anode is arranged in the anode reaction tank; the cathode has a surface structure and / or surface characteristics that are easy for bubble detachment. The electrochemical reaction device of the seawater pretreatment device effectively inhibits electrode scaling through the design of a cathode structure and regulation and control of reaction parameters, so that long-acting and stable operation of an electrochemical and air flotation coupling process is ensured, the seawater pretreatment device not only undertakes an agent-free seawater softening function, but also shares part of algae removal load, and the seawater pretreatment effect is improved. And the air floatation effect can be enhanced through suspended calcium and magnesium particles and bubbles generated by electrochemical reaction, so that algae and hardness in seawater can be efficiently and synergistically removed.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and specifically relates to a seawater pretreatment device and a method for pretreating seawater using the same. Background Technology

[0002] Efficient pretreatment of impurities such as hardness ions, algae, suspended solids, and oils in seawater is a necessary step to ensure the long-term stable operation of seawater desalination systems and is also a bottleneck restricting the development of the seawater desalination industry. The conventional pretreatment process is "coagulation sedimentation + filtration + ultrafiltration". The air flotation process can directly replace the above three process units, greatly simplifying the process flow and reducing investment and operating costs.

[0003] However, the ability of air flotation to remove dissolved hardness ions (calcium and magnesium) and algae is limited by the morphology and adhesion mechanism of air bubbles, necessitating the addition of additional chemical agents during pretreatment. This not only consumes a large amount of chemicals but also restricts the utilization and discharge of concentrated seawater. Therefore, the efficiency of seawater pretreatment using air flotation alone is not ideal.

[0004] Existing technologies utilize electrochemical techniques to remove hardness ions and algae from water, enhancing the pretreatment process of single-stage air flotation technology. However, when electrochemical technology is used for seawater treatment, oxygen reduction and hydrogen evolution reactions occur at the cathode, producing OH-. － Ions, these OH- － With HCO3 in solution － Ions combine to form CO3 2－ Ions. Subsequently, OH- － Ions and Mg 2+ CO3 2－ Ions and Ca 2+ The reaction on the cathode surface produces precipitates, which are deposited on the cathode surface, eventually leading to cathode scaling. This hinders the long-term, stable operation of the electrochemical and air flotation coupled processes, and the combination of the two has not achieved the desired progress. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention proposes a seawater pretreatment device and a method for pretreating seawater using the same. This pretreatment method comprises two processes: electrochemical softening and primary algae removal, and secondary algae removal via air flotation. The electrochemical process, through the design of the electrochemical reaction device and the control of reaction parameters, effectively inhibits electrode scaling, thereby ensuring the long-term and stable operation of the coupled electrochemical and air flotation processes. It not only performs the chemical-free softening function of seawater but also shares part of the algae removal load. Furthermore, the suspended calcium and magnesium particles and bubbles generated by the electrochemical reaction enhance the air flotation effect, achieving efficient and synergistic removal of algae and hardness from seawater.

[0006] Specifically, the first objective of the present invention is to provide a seawater pretreatment device, which includes an electrochemical reaction device, the electrochemical reaction device including a cathode reaction tank, an anode reaction tank and a barrier for separating the cathode reaction tank and the anode reaction tank; The cathode reaction tank is provided with a cathode, and the anode reaction tank is provided with an anode; The cathode has a surface structure and / or surface properties that facilitate bubble detachment.

[0007] Furthermore, multiple cathodes are provided, and the multiple cathodes are arranged in an alternating manner to form a serpentine channel; The barrier includes barrier a and barrier b; The surface properties that facilitate bubble detachment include surface hydrophobic treatment; The surface structure that facilitates bubble detachment includes at least one of non-planar morphology, porous structure, and rough texture.

[0008] Furthermore, the anode (4) and the barrier a and the barrier b are stacked along the thickness direction, the barrier a is close to the anode, the barrier b is close to the cathode, and the anode and cathode are arranged in a T-shape.

[0009] Furthermore, the distance between the farthest end of the cathode and the surface of the anode is <100 cm, and the distance between the cathodes is 0.1~20 mm.

[0010] Furthermore, it also includes an air flotation device; The electrochemical reaction device has an electrochemical inlet and an electrochemical outlet on opposite sidewalls; the electrochemical inlet is positioned lower than the electrochemical outlet.

[0011] Furthermore, the air flotation device includes an air flotation inlet, an air pump, a dissolved air tank, an air delivery pipe, a skimmer, and an air flotation outlet; The electrochemical outlet and the air flotation inlet are connected, and a valve is provided between the electrochemical outlet and the air flotation inlet.

[0012] Furthermore, the material of the barrier a is one of ion exchange membrane, carbon cloth, carbon felt, polytetrafluoroethylene, polypropylene, polyimide fiber, polyurethane, phenolic resin and epoxy ester. The barrier material b is one of the following: ion exchange membrane, polystyrene, polytetrafluoroethylene, polyphenylene sulfide, aliphatic polyketone, polyvinyl chloride, and carbon fiber. The hydrophobication treatment involves applying a polytetrafluoroethylene coating or a diamond-like carbon coating. The non-planar shape is at least one of curved surface, inclined surface, and arc surface; The porous structure is at least one of foamed metal, porous ceramic, and metal wire mesh.

[0013] Furthermore, the cathode is a metal wire mesh, and the curvature of each wire mesh is 0.2~100 mm. -1 ; The cathode material is one of stainless steel, iron, copper, titanium, nickel, metal alloy, graphite, carbon nanotubes, or biomass carbon.

[0014] The cathode contains micro / nano-scale channel or tip structures.

[0015] A second objective of this invention is to provide a seawater pretreatment method, wherein the method uses the seawater pretreatment apparatus provided in this application to treat seawater, and the method includes the following steps: The primary electrochemical reaction device is filled with seawater and the power is turned on to carry out primary pretreatment of seawater. After the power is turned on for 10-35 minutes in step (1), open the valve to allow the seawater that has completed the primary pretreatment to enter the air flotation device; The air flotation device is used to treat the seawater after the primary pretreatment in step (2).

[0016] Furthermore, step (1) also includes introducing CO2 into the cathode reaction cell at a flow rate of 10 mL / min; The reaction current density in step (1) is 0.1~200 mA / cm². 2 ; The electrochemical reaction device also includes a flow meter.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) For the first time, it was proposed to use electrochemical technology to convert hardness ions into suspended calcium and magnesium particles for adsorbing algae in seawater, thereby achieving the removal and resource utilization of hardness ions in seawater. (2) Electrode scaling was effectively suppressed by designing the electrochemical device and controlling the reaction parameters, thereby ensuring the long-term and stable operation of the electrochemical and air flotation coupling process; (3) The electrochemical and air flotation technologies are effectively combined for seawater pretreatment. On the one hand, the electrochemical technology is used to adjust the seawater quality, which is conducive to the efficient flotation performance of air flotation. On the other hand, the air flotation device generates bubbles to eliminate calcium and magnesium particles generated in the water during the electrochemical process, preventing them from settling at the bottom of the device for secondary treatment. Thus, a new integrated process and method for efficient seawater pretreatment with electrochemical enhanced air flotation is constructed. (4) The high efficiency of the electrochemical process gives the pretreatment process the ability to remove algae and hardness quickly in a short time, which can reduce the construction scale and initial investment of single air flotation and other conventional pretreatment equipment. Attached Figure Description

[0018] Figure 1 A schematic diagram of an electrochemical reaction device for a seawater pretreatment apparatus provided in this application embodiment; Figure 2 Scanning electron microscope image of bubbles generated on the cathode surface; Figure 3 Scanning electron microscope (SEM) image of particles in an electrochemical cathode reaction cell; Figure 4 A schematic diagram of an air flotation device for a seawater pretreatment apparatus provided in this application embodiment; Explanation of reference numerals in the attached diagram: 1-Electrochemical inlet; 2-Cathode reaction tank; 3-Anode reaction tank; 4-Anode; 5-Barrier a; 6-Barrier b; 7-Cathode; 8-Electrochemical outlet; 9-Air flotation inlet; 10-Air pump; 11-Dissolved air tank; 12-Air supply pipe; 13-Foam scraper; 14-Air flotation outlet; 15-Air flotation device. Detailed Implementation

[0019] To further illustrate the present invention, the following detailed description is provided in conjunction with embodiments. However, these descriptions should not be construed as limiting the scope of protection of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] The first objective of this application is to provide a seawater pretreatment device, including a primary electrochemical reaction device. The primary electrochemical reaction device includes a cathode reaction tank, an anode reaction tank, and a barrier separating the cathode reaction tank and the anode reaction tank. A cathode is disposed in the cathode reaction tank, and an anode is disposed in the anode reaction tank. The cathode has a surface structure and / or surface characteristics that facilitate bubble detachment. Electrochemical inlets and outlets are respectively disposed on the opposite sidewalls of the electrochemical reaction device. The principle of seawater pretreatment using the electrochemical reaction device in this application is as follows: hardness ions are converted into suspended calcium and magnesium particles through electrochemical technology to adsorb algae in seawater, thereby achieving the removal and resource utilization of hardness ions in seawater.

[0021] Specifically, the electrochemical reaction device provided in this application includes an electrochemical inlet and an electrochemical outlet, allowing seawater to enter the device for pretreatment through the inlet and exit through the outlet after pretreatment. Seawater first enters the cathode reaction tank. During the flow, some seawater permeates through barriers and enters the anode reaction tank. The cathode reaction tank is equipped with a cathode featuring a surface structure and / or surface characteristics that facilitate bubble detachment, while the anode reaction tank contains an anode. After the electrochemical reaction device is filled with seawater, a reaction current and voltage are applied. In the cathode reaction tank, water is decomposed on the cathode surface to generate hydrogen bubbles and hydroxide ions. Due to the cathode's surface structure and / or surface characteristics that facilitate bubble detachment, the adhesion between the electrode surface and the bubbles is weakened. The generated bubbles immediately carry hydroxide ions into the seawater bulk phase, providing a suitable alkaline environment for the liquid-phase deposition of calcium and magnesium ions in the seawater and the modification of algal surfaces.

[0022] For the anode, in principle, it is sufficient to have excellent conductivity and resistance to chlorine corrosion. In some preferred embodiments of the present invention, the anode is selected from commercially available ruthenium-iridium-titanium mesh.

[0023] In one embodiment of this application, the barrier includes barrier a and barrier b; barrier a is made of one of the following materials: ion exchange membrane, carbon cloth, carbon felt, polytetrafluoroethylene, polypropylene, polyimide fiber, polyurethane, phenolic resin, and epoxy ester; barrier b is made of one of the following materials: ion exchange membrane, polystyrene, polytetrafluoroethylene, polyphenylene sulfide, aliphatic polyketone, polyvinyl chloride, and carbon fiber.

[0024] In one embodiment of this application, barrier a has the property of being resistant to strong acids, which can prevent the acid generated in the anode reaction zone from interfering with the cathode reaction zone; barrier b has the property of being resistant to strong alkalis, which can prevent the alkaline solution generated in the cathode reaction zone from penetrating into the anode reaction zone.

[0025] In one embodiment of this application, the surface characteristics of the cathode that facilitate bubble detachment include a surface hydrophobic treatment, which is to provide a hydrophobic coating such as a polytetrafluoroethylene coating or a diamond-like carbon coating; the surface structure of the cathode that facilitates bubble detachment includes one of a non-planar shape, a porous structure, and a rough structure, wherein the non-planar shape is at least one of a curved surface, an inclined surface, and an arc surface; and the porous structure is at least one of a foamed metal or a porous ceramic.

[0026] In one embodiment of this application, the cathode is a metal mesh, and the curvature of each metal wire in the metal mesh electrode is 0.2~100 mm. -1 Metal mesh, as a cathode, not only facilitates the generation and detachment of micro and nano bubbles, but its porous structure also promotes bubble diffusion.

[0027] In one embodiment of this application, in order to ensure a uniform electric field distribution, the anode, the barrier a, and the barrier b are stacked along the thickness direction, the barrier a is close to the anode, and the barrier b is close to the cathode. In order to ensure the cathode packing density, the anode and the cathode are placed in a T-shape.

[0028] In one embodiment of this application, in order to ensure the uniformity of the electric field and current density distribution, the distance between the farthest end of the cathode and the surface of the anode is <100 cm, and the distance between the cathodes is 0.1~20 mm.

[0029] In one embodiment of this application, the air flotation device is connected after the electrochemical reaction device. This allows for the flotation removal of calcium and magnesium particles generated during the electrochemical water treatment process, preventing particle deposition at the bottom of the container and reducing sludge discharge costs. Furthermore, the destabilization of algae in the seawater after electrochemical treatment solves the problem of low algae removal efficiency in air flotation. Therefore, after further air flotation treatment, the algae removal rate of seawater treated electrochemically can be increased to over 99%. The seawater pretreatment device also includes a secondary air flotation device, with the electrochemical outlet and the air flotation inlet connected. A valve is installed between the electrochemical outlet and the air flotation inlet.

[0030] In one embodiment of this application, the electrochemical inlet is positioned lower than the electrochemical outlet, which not only facilitates the discharge of suspended particles generated during pretreatment, but also allows the electrolyte in the electrolytic cell to flow from bottom to top. The shear force generated by the electrolyte fluid can "wash away" and remove air bubbles from the electrode surface, further making it easier for the air bubbles generated during electrolysis to detach from the cathode and diffuse in the solution.

[0031] The second objective of this application is to provide a seawater pretreatment method, which includes two processes: electrochemical softening and primary algae removal in an electrochemical device, and secondary algae removal via air flotation in an air flotation device. The electrochemical process not only performs the chemical-free softening function of seawater but also shares part of the algae removal load. Furthermore, the suspended calcium and magnesium particles and bubbles generated by the electrochemical reaction enhance the air flotation effect, achieving efficient and synergistic removal of algae and hardness from seawater. The seawater pretreatment method includes the following steps: Seawater is injected into the primary electrochemical reaction device and the power is turned on to carry out primary pretreatment of seawater. After the power is turned on for 10-35 minutes in step (1), the valve allows the seawater that has completed the primary pretreatment to enter the air flotation device. The air flotation device is used to treat the seawater after the primary pretreatment in step (2).

[0032] In one embodiment of this application, step (1) further includes introducing CO2 into the cathode reaction cell at a flow rate of 10 mL / min.

[0033] In one embodiment of this application, the reaction current density in step (1) is 0.1~200 mA / cm². 2 When the cathode reaction current density is controlled within 0.1~200 mA / cm² 2 By controlling the seawater residence time in the electrochemical reactor to 0.5–30 min, the size of the calcium and magnesium particles can be controlled, resulting in particles ranging from 10 to 10⁻⁶. 5 nm. Calcium and magnesium particles within this range can ensure the efficient flotation performance of the subsequent air flotation device. Otherwise, if the calcium and magnesium particles are too small, the bubbles generated by air flotation will have difficulty adhering to the particles; if the calcium and magnesium particles are too large, the buoyancy of the bubbles will be insufficient, and the calcium and magnesium particles will settle at the bottom of the device.

[0034] In one embodiment of this application, the reaction current density is 0.1~200 mA / cm². 2 Under certain conditions, the bubble size can also be controlled, allowing the bubble diameter to range from 10 to 3 × 10⁻⁶. 5 nm can efficiently combine with calcium and magnesium particles and algae, thereby enhancing flotation performance.

[0035] In one embodiment of this application, the reaction current density is 0.1~200 mA / cm². 2 With a hydraulic residence time of 0.5 to 30 minutes, the seawater pH range is 7 to 12. Under the influence of seawater pH, the algal substance interface changes. Combined with the adsorption-flotation dual effect of calcium and magnesium particles and bubbles, a solid / liquid / gas three-phase mixture is formed and enters the air flotation device from the air flotation inlet connected to the electrochemical inlet, thereby enhancing the air flotation performance. Example 1

[0036] This embodiment provides a seawater pretreatment method using the seawater pretreatment device provided in this application. The seawater pretreatment device includes an electrochemical reaction device, and the method includes an electrochemical softening and primary algae removal process within the electrochemical reaction device. Figure 1 As shown, the electrochemical reaction device includes a cathode reaction tank 2, an anode reaction tank 3, and a barrier separating the cathode reaction tank 2 and the anode reaction tank 3; a cathode 7 is disposed in the cathode reaction tank 2, and an anode 4 is disposed in the anode reaction tank 3; the cathode 7 has a curvature of 0.67 mm. -1 The device uses a stainless steel wire mesh, with eight cathodes arranged in a staggered, serpentine channel. The distance between the farthest end of cathode 7 and the surface of anode 4 is 80 cm, and the distance between cathodes is 10 mm. A commercially available ruthenium-iridium-titanium mesh is used as the anode. Electrochemical inlet 1 and electrochemical outlet 8 are respectively located on the opposite sidewalls of the electrochemical reaction device. The barrier material b6 is polytetrafluoroethylene, and the barrier material a5 is an ion exchange membrane.

[0037] In this embodiment, the seawater pretreatment method specifically involves continuously injecting seawater into the electrochemical reaction device using a pressure pump. The hydraulic residence time of the seawater in the electrochemical reaction tank is adjusted to 15 minutes using a flow meter. After the reactor is filled with seawater, a regulated DC power supply is connected, and a voltage of 10 mA / cm is applied to the stainless steel wire mesh cathode 7. 2 The current density is such that the curvature of the stainless steel wire is 0.67 mm. -1 Combining Figure 2 Using in-situ observation technology, it was observed that after the application of the reaction current, a large number of micron-sized bubbles detached from the surface of the metal wire and entered the solution. The bubble size was less than 30 μm. Due to the migration behavior of the micron-sized bubbles, the pH value of the solution reached 11.8 within 15 minutes, forming an alkaline environment suitable for the deposition reaction of calcium and magnesium ions. As shown in Table 1, after treatment with the electrochemical device, the removal rates of calcium and magnesium ions in actual seawater taken from the vicinity of a coastal city reached 33.3% and 96.1%, respectively.

[0038] Table 1 shows the water quality parameters of the actual seawater before and after treatment by the electrochemical device in this embodiment.

[0039] Table 1

[0040] After calcium and magnesium ions are removed, they precipitate as particles in the seawater of the cathode reactor. Figure 3 It is known that the calcium and magnesium particles precipitated in the solution are <15 μm in size and exist in seawater in a suspended state. They can not only serve as nucleation sites for scale to inhibit cathodic scaling, but also have the function of adsorbing and removing algae. Example 2

[0041] This embodiment provides a seawater pretreatment method using the seawater pretreatment device provided in this application. The seawater pretreatment device includes an electrochemical reaction device, and the method includes an electrochemical softening and primary algae removal process within the electrochemical reaction device. Figure 1 As shown, the electrochemical reaction device includes a cathode reaction tank 2, an anode reaction tank 3, and a barrier separating the cathode reaction tank 2 and the anode reaction tank 3; a cathode 7 is disposed in the cathode reaction tank 2, and an anode 4 is disposed in the anode reaction tank 3; the cathode 7 has a curvature of 0.67 mm. -1 The device uses a stainless steel wire mesh, with eight cathodes arranged in a staggered, serpentine channel. The distance between the farthest end of cathode 7 and the surface of anode 4 is 20 cm, and the distance between cathodes is 20 mm. A commercially available ruthenium-iridium-titanium mesh is used as the anode. Electrochemical inlet 1 and electrochemical outlet 8 are respectively located on the opposite sidewalls of the electrochemical reaction device. Both barrier material b6 and barrier material a5 are made of polytetrafluoroethylene (PTFE).

[0042] In this embodiment, the seawater pretreatment method specifically involves continuously injecting seawater into the electrochemical reaction device using a pressure pump. The hydraulic residence time of the seawater in the electrochemical reaction tank is adjusted to 30 minutes using a flow meter. After the reactor is filled with seawater, a regulated DC power supply is connected, and a voltage of 19 mA / cm is applied to the stainless steel wire mesh cathode. 2 The current density was measured. Furthermore, CO2 was introduced into the cathode reaction tank at a flow rate of 10 mL / min. After treatment by the electrochemical device, as shown in Table 2, the removal rates of calcium and magnesium ions reached 88.1% and 93.4%, respectively, and the algae removal rate reached 25.8%.

[0043] Table 2. Water quality parameters of actual seawater before and after treatment by the electrochemical device in this embodiment. Table 2 Example 3

[0044] This embodiment provides a seawater pretreatment method, which uses the seawater pretreatment device provided in this application to pretreat seawater. The seawater pretreatment device includes an electrochemical reaction device and an air flotation device. The method includes two processes: electrochemical softening and primary algae removal in the electrochemical reaction device and secondary algae removal by air flotation in the air flotation device. In this embodiment, the electrochemical reaction device and the electrochemical reaction process are the same as those in Example 2. After the seawater undergoes the electrochemical treatment process in Example 2, it is further subjected to an air flotation treatment process.

[0045] In this embodiment, the air flotation process occurs in the air flotation device 15, combined with Figure 4 The air flotation device 15 includes an air flotation inlet 9, an air pump 10, a dissolved air tank 11, an air supply pipe 12, a skimmer 13, and an air flotation outlet 14. After the electrochemical treatment step in Example 2, seawater containing calcium and magnesium particles, microbubbles, and residual algae flows out from the electrochemical outlet 8 and then enters the air flotation device 15 through the air flotation inlet 9. After staying in the air flotation device for 60 minutes, as shown in Table 3, the removal rates of calcium and magnesium ions reached 95.2% and 98.8%, respectively, and the algae removal rate also reached 96.3%, achieving efficient removal of hardness ions and algae.

[0046] Table 3 shows the actual seawater quality parameters before and after treatment by the air flotation device in this embodiment. Table 3

[0047] Comparative Example 1 In this embodiment, the cathode in Example 1 is replaced with a stainless steel plate. As shown in Table 4, the actual seawater taken from the vicinity of a coastal city was treated by an electrochemical device, and the removal rates of calcium and magnesium ions reached 4.7% and 41.4%, respectively.

[0048] Table 4 shows the actual seawater quality parameters before and after treatment by the electrochemical device. Table 4

[0049] Comparative Example 2 In this embodiment, the only difference is that the current density applied to the cathode in Example 1 is replaced with 29 mA / cm². 2 As shown in Table 5, the removal rates of calcium and magnesium ions in the actual seawater taken from the vicinity of a coastal city reached 21.4% and 84.4% respectively after treatment by the electrochemical device.

[0050] Table 5 shows the actual seawater quality parameters before and after treatment by the electrochemical device. Table 5

[0051] It should be noted that while the preferred embodiments of the present invention are given in the specification and accompanying drawings, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of the present invention; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of the present invention. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of the present invention specification. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A seawater pretreatment device, characterized in that, The device includes an electrochemical reaction device, which includes a cathode reaction tank (2), an anode reaction tank (3), and a barrier for separating the cathode reaction tank (2) and the anode reaction tank (3); The cathode reaction tank (2) is provided with a cathode (7), and the anode reaction tank (3) is provided with an anode (4); The cathode (7) has a surface structure and / or surface properties that facilitate bubble detachment.

2. The seawater pretreatment device according to claim 1, characterized in that, Multiple cathodes (7) are provided, and the multiple cathodes (7) are arranged in an alternating manner to form a serpentine channel; The barrier includes barrier a (5) and barrier b (6); The surface properties that facilitate bubble detachment include surface hydrophobic treatment; The surface structure that facilitates bubble detachment includes at least one of non-planar morphology, porous structure, and rough texture.

3. The seawater pretreatment device according to claim 2, characterized in that, The anode (4) is stacked with the barrier a (5) and the barrier b (6) along the thickness direction. The barrier a (5) is close to the anode (4), and the barrier b (6) is close to the cathode (7). The anode (4) and the cathode (7) are arranged in a T-shape.

4. A seawater pretreatment device according to claim 3, characterized in that, The distance between the farthest end of the cathode (7) and the surface of the anode (4) is <100 cm, and the distance between the cathodes (7) is 0.1~20 mm.

5. A seawater pretreatment device according to any one of claims 1-4, characterized in that, It also includes an air flotation device (15); The electrochemical reaction device has an electrochemical inlet (1) and an electrochemical outlet (8) on opposite sidewalls; the electrochemical inlet (1) is positioned lower than the electrochemical outlet (8).

6. A seawater pretreatment device according to claim 5, characterized in that, The air flotation device includes an air flotation inlet (9), an air pump (10), a dissolved air tank (11), an air supply pipe (12), a skimmer (13), and an air flotation outlet (14); The electrochemical outlet (8) and the air flotation inlet (9) are connected, and a valve is provided between the electrochemical outlet (8) and the air flotation inlet (9).

7. The seawater pretreatment device according to claim 6, characterized in that, The material of the barrier a(5) is one of the following: ion exchange membrane, carbon cloth, carbon felt, polytetrafluoroethylene, polypropylene, polyimide fiber, polyurethane, phenolic resin and epoxy ester. The material of the barrier b (6) is one of the following: ion exchange membrane, polystyrene, polytetrafluoroethylene, polyphenylene sulfide, aliphatic polyketone, polyvinyl chloride and carbon fiber; The hydrophobication treatment involves applying a polytetrafluoroethylene coating or a diamond-like carbon coating. The non-planar shape is at least one of curved surface, inclined surface, and arc surface; The porous structure is at least one of foamed metal, porous ceramic, and metal wire mesh.

8. The seawater pretreatment apparatus according to claim 7, characterized in that, The cathode (7) is a metal wire mesh, and the curvature of each wire mesh is 0.2~100 mm. -1 ; The cathode (7) is made of one of the following materials: stainless steel, iron, copper, titanium, nickel, metal alloy, graphite, carbon nanotubes or biomass carbon. The cathode (7) contains micro / nano-scale channel or tip structures.

9. A seawater pretreatment method, characterized in that, The method uses the seawater pretreatment device according to claim 8 to treat seawater, and the method includes the following steps: The primary electrochemical reaction device is filled with seawater and the power is turned on to carry out primary pretreatment of seawater. After the power is turned on for 10-35 minutes in step (1), open the valve to allow the seawater that has completed the primary pretreatment to enter the air flotation device (15); The air flotation device (15) is used to treat the seawater after the primary pretreatment in step (2).

10. A seawater pretreatment method according to claim 9, characterized in that, Step (1) also includes introducing CO2 into the cathode reaction tank (2) at a flow rate of 10 mL / min; The reaction current density in step (1) is 0.1~200 mA / cm². 2 ; The electrochemical reaction device also includes a flow meter.

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