A device and method for advanced treatment of sewage by simultaneous desilication and defluorination

Abstract

A simultaneous desiliconization and defluorination wastewater advanced treatment device and method are disclosed. This invention relates to a precipitation device and method for removing silicon and fluoride from water, aiming to solve the technical problems of low silicon removal efficiency, large amounts of added chemicals, complex operation, and high cost of existing silicon removal methods. The device of this invention is a pool with a central baffle dividing the pool into a coagulation zone and a sedimentation zone. A stirrer, a first spiral heating tube, and a first inclined plate are installed in the coagulation zone; a second inclined plate, a filter device, and a second spiral heating tube are installed in the sedimentation zone; an electro-adsorption device is installed at the lower end of the baffle. Wastewater treatment method: Wastewater containing silicon and / or fluoride is introduced into the coagulation zone, sodium aluminate and a coagulant are added, and heating and stirring are performed for coagulation and sedimentation. After electro-adsorption flocculation and sedimentation by the electro-adsorption device, the wastewater enters the sedimentation zone for enhanced sedimentation, overflows, and the treatment is completed. The silicon removal rate reaches 92%–98%, and the fluoride removal rate is higher than 71.43%. It can be used in the field of wastewater treatment.

Description

Technical Field

[0001] This invention relates to a precipitator and method for removing silicon and fluoride from water, belonging to the field of wastewater treatment. Background Technology

[0002] Silicon compounds are a common pollutant in industrial production processes. Due to their unique chemical properties, they easily form silica scale in equipment and pipelines. Silica scale formation is particularly prevalent in advanced wastewater treatment plants and saline wastewater treatment systems, especially during the operation of equipment such as reverse osmosis and evaporators. The accumulation of silica scale not only reduces the treatment efficiency of the equipment but also causes serious damage. For example, silica scale frequently clogs reverse osmosis membranes, leading to decreased membrane permeability and a gradual reduction in treated water volume. After prolonged operation, the desalination performance of the reverse osmosis membrane gradually decreases due to the effects of silica scale. To maintain equipment performance, more frequent chemical cleaning is required, which not only increases maintenance costs but also shortens the membrane's lifespan. Furthermore, evaporator heat exchangers and falling film tubes are also frequently affected by silica scale. As silica scale accumulates, the thermal conductivity of these devices decreases, leading to increased heat loss and a lower energy efficiency ratio. To address the problem of insufficient treated water volume, high-pressure cleaning and chemical cleaning are required on average every six months. This not only increases operating costs but also affects the stable operation of the equipment. Therefore, for industrial production, the removal of silica from process wastewater is crucial.

[0003] Existing main methods for silicon removal include physical removal and chemical removal. Physical methods, such as filtration and precipitation, remove silicon. These methods are simple to operate and have low equipment maintenance costs, but their removal efficiency is relatively low and they usually need to be used in conjunction with other silicon removal methods. Chemical methods convert silicates into insoluble precipitates through chemical reactions, which are then removed by filtration. This method requires the use of silicon-removing agents in an alkaline environment. Commonly used silicon-removing agents include lime, magnesium chloride, and sodium aluminate. Adding an appropriate amount of polyacrylamide can accelerate coagulation and sedimentation. Alternatively, silicon can be converted into less soluble silicates through chemical reactions in a high-concentration NaOH solution, which are then removed by filtration. This method has a high desilication rate, but the overall process is time-consuming and energy-intensive, and the product particles are coarse and unevenly distributed. Magnesium oxide and lime can also be used together to ensure desilication effectiveness. The optimal pH for magnesium oxide desilication is 10.1–10.3; to ensure this pH value, it is necessary to add lime to the treatment system. Simultaneously, appropriate coagulants can improve the properties of magnesium oxide sludge and enhance the silicon removal effect. Among the existing silicon removal methods, physical methods have low efficiency and need to be used in conjunction with other methods; chemical methods require the addition of different types of chemical agents, making them complex and costly. Furthermore, existing silicon removal technologies generally suffer from high investment, large equipment requirements, and high energy consumption, making it difficult to meet environmental protection requirements. Summary of the Invention:

[0004] The present invention aims to solve the technical problems of low silicon removal efficiency, large amount of reagents, complex operation and high cost of existing silicon removal methods, and to provide a wastewater deep treatment device and method for simultaneous silicon removal and fluoride removal.

[0005] The wastewater deep treatment device for simultaneous desiliconization and defluorination of the present invention includes a tank body 1, a baffle 2, an electro-adsorption device 3, a stirrer 4, a first spiral heating tube 5, a first inclined plate 6, a filter device 8, a second spiral heating tube 9, and a second inclined plate 7.

[0006] A sludge collection trough 1-1 is set at the center of the bottom of the pool body 1; the bottom of the pool body 1 is inclined to the sludge collection trough 1-1; a baffle 2 is set in the middle of the pool body 1, dividing the pool body 1 into a coagulation zone 1-2 and a sedimentation zone 1-3; an electro-adsorption device 3 is fixed at the lower end of the baffle 2; the electro-adsorption device 3 is opposite to the sludge collection trough 1-1 and has a gap so that water can flow from the coagulation zone 1-2 to the sedimentation zone 1-3.

[0007] An inlet 1-2-1 is provided on the upper side wall of the coagulation zone 1-2. The agitator 4 and the first spiral heating pipe 5 are located in the middle of the coagulation zone 1-2. The first inclined plate 6 is located at the bottom of the coagulation zone 1-2 and tilts towards the mud collection trough 1-1.

[0008] An outlet 1-3-1 is provided on the upper side wall of the sedimentation zone 1-3, a filter device 8 is provided below the outlet 1-3-1, a second spiral heating pipe 9 is provided in the middle of the sedimentation zone 1-3, and a second inclined plate 7 is provided at the bottom of the sedimentation zone 1-3 and inclined towards the sludge collection trough 1-1.

[0009] Furthermore, steam is introduced into the first spiral heating tube 5 and the second spiral heating tube 9 for heating; the high-temperature steam in the spiral heating tubes is waste heat generated during industrial production.

[0010] Furthermore, the electrode preparation method of the electroadsorption device is as follows: (1) MAX phase powder Ti3C2T xAdd to hydrofluoric acid aqueous solution and stir for 30-60 min. After centrifugation, wash the solid with distilled water until the pH of the supernatant reaches 4-6. Then, separate by ultrasonication to obtain MXene dispersion; (2) Add aluminum nitrate, nickel nitrate and titanium sulfate solution to MXene dispersion and adjust the pH to weakly alkaline during continuous stirring; after standing for 1 h, centrifuge and wash the solid obtained by centrifugation with distilled water and ethanol respectively, vacuum dry, and then place in a high temperature furnace and heat to 800-820℃ in argon atmosphere for 2-3 h to obtain electrolytic crystals. The electrode material is TiNiAl-MXene nanopowder; (3) According to the electrode material, carbon black and PVDF emulsion with a mass percentage concentration of 10% to 11% and a mass ratio of (8 to 8.5):(1 to 1.2):1, the electrode material, carbon black and PVDF emulsion with a mass percentage concentration of 10% to 11% are added to N-methylpyrrolidone (NMP), ultrasonically treated for 10 to 20 minutes, then coated onto the electrode plate, and dried in a vacuum drying oven to obtain the electrode of the electroadsorption device, namely the TiNiAl-MXene material electrode. The electrode is prepared by using TiNiAl-MXene nanopowder as the electrode material. By modifying MXene with Ti, Ni and Al, the specific surface area of ​​MXene material is increased. The specific surface area after modification can reach 695m². 2 The / g ratio provides more adsorption sites, enhancing the adsorption capacity of MXene material electrodes for fluorine and silicon in water. After preparation, the electrode exhibits high selective adsorption capacity for fluorine and silicon in water; even in the presence of interfering substances such as phosphorus and chlorine, the adsorption capacity for silicon and fluorine remains significantly higher than that for phosphorus and chlorine. Controllable directional fabrication of the material can be achieved by adjusting the proportions of aluminum nitrate, nickel nitrate, and titanium sulfate solutions.

[0011] The device of this invention is mainly divided into two main areas: a coagulation zone with heating and stirring on the left and a sedimentation zone with heating on the right. When wastewater enters the coagulation zone of the reaction device, the reagent is also added simultaneously. Through the powerful stirring of the stirring device, the wastewater and reagent are fully mixed and contacted, laying the foundation for the subsequent coagulation and sedimentation process. The spiral heating tube is an important part of the device, located in the middle of the entire device. It cleverly utilizes heat pump technology to introduce the waste heat generated during the production process. Through heat convection generated by uneven heating, the mixed liquid becomes more uniform, further promoting the rapid settling of the precipitate. The electro-adsorption device at the bottom of the baffle further treats the coagulated water. Using specific electrode materials, silicon and fluorine are adsorbed onto the surface, and under the action of the electric field, they flocculate and precipitate with the particulate matter, improving the removal rate of silicon and fluorine. At the bottom of the device, an inclined plate sedimentation device is designed, which helps guide the water flow to a uniform distribution, avoiding dead zones and the formation of eddies. This not only improves the sedimentation effect but also ensures the stable operation of the entire system. During the treatment process, the collected coagulated sludge undergoes appropriate sludge treatment to ensure the integrity of wastewater treatment. The high-temperature steam in the spiral heating tubes primarily originates from waste heat generated during industrial production. This heat energy is absorbed by the cooling water, processed by the evaporator and compressor, and finally transported to the coagulation unit. In this process, the coagulation unit fully utilizes the heat energy in the water, achieving highly efficient heat enhancement and thermal sedimentation.

[0012] The advanced treatment method for simultaneous desiliconization and defluorination of wastewater using the above-mentioned device is carried out according to the following steps:

[0013] 1. Wastewater containing silicon and / or fluorine is introduced into coagulation zone 1-2 through inlet 1-2-1. Sodium aluminate and coagulant are added to coagulation zone 1-2 at the same time. Sodium aluminate is added at a mass ratio of NaAlO2:Si = (8~8.5):1, and the concentration of coagulant is 30~35mg / L. The water temperature in coagulation zone 1-2 is heated to 80~85℃ using the first spiral heating tube. The water is hydraulically retained for 30~50min under a stirring speed of 200~300rpm. In this step, the wastewater, sodium aluminate, and coagulant are mixed and contacted under stirring, and coagulation and sedimentation occur under the effect of thermal enhancement.

[0014] 2. When the wastewater that has been pre-treated in the coagulation zone 1-2 passes through the electro-adsorption device 3, it undergoes electro-adsorption flocculation and sedimentation. Then it enters the sedimentation zone 1-3, where the water is heated to 60-65°C using the second spiral heating tube 9 for enhanced sedimentation treatment for 30-50 minutes. After being filtered by the filtration device, it overflows and is discharged from the outlet 1-3-1. The sediment enters the sludge collection tank and is discharged under the promotion of the first inclined plate 6 and the second inclined plate 7.

[0015] This invention, aimed at reducing silica scale buildup in wastewater and mitigating its impact on equipment stability and lifespan, presents a device and method for simultaneous desiliconization and fluoride removal via thermally enhanced coagulation. The simultaneous removal of silicon, fluoride, and calcium is achieved through a sodium aluminate desiliconization reaction and chemical reactions between sodium aluminate and fluorine and calcium. The specific reactions in this process are shown below:

[0016] 2Na2SiO3+2NaAlO2+2H2O=Na2Al2Si2O8↓+4NaOH (1)

[0017] AlO2 - +F - +2H₂O=AlF₃↓+OH - (2)

[0018]

[0019] Ca 2+ +2OH - +Mg 2+ +4OH-=Ca(OH)2↓+Mg(OH)2↓ (4)

[0020] 3Ca(OH)2+2Al(OH)3=3CaAlO2+6H2O (5)

[0021] Ferrous sulfate or polyaluminum chloride (PAC) is mainly used as a coagulant in wastewater treatment. Its mechanism of action is to destabilize tiny suspended solids and colloidal impurities in water, forming larger flocs that facilitate sedimentation and filtration. This effectively removes impurities and improves water quality. The main function of coagulants is to neutralize these negative charges, making them unstable and prone to aggregation. Coagulant aids work by bridging suspended solid particles, causing them to settle rapidly. Thermal intensification primarily promotes coagulation by increasing water temperature. Higher temperatures increase the probability of collisions and accelerate chemical reactions, thus enhancing coagulation. Thermal intensification also increases the rate of ion movement, shortening the mean free path between ions in water, leading to more frequent ion collisions. This promotes ion reactions, increases reaction rates, and makes ions more likely to aggregate into ion pairs or clusters, thereby reducing hydraulic retention time. Compared to traditional coagulation technology, the thermal convection generated by localized heating allows for more uniform mixing of suspended particles, colloidal particles, and dissolved substances in the water, thereby improving mass transfer efficiency and facilitating collision and bonding between coagulants and particulate matter. Under the influence of an electric field, silicate ions are adsorbed by the electrode and converted into silicic acid. This step is crucial for electro-adsorption of silicon, and the performance of the electrode material significantly impacts the adsorption effect of silicon ions. TiNiAl-MXene electrode material, through the modification of MXene with Ti, Ni, and Al, increases the specific surface area of ​​the MXene material, providing more adsorption sites and enhancing the adsorption capacity of the MXene electrode for fluoride and silicon in water. Simultaneously, this electrode material exhibits high selective adsorption capacity for fluoride and silicon in water; even in the presence of interfering substances such as phosphorus and chlorine, the adsorption capacity for silicon and fluoride remains far higher than that for phosphorus and chlorine. Furthermore, in the preparation process of TiNiAl-MXene material, the proportions of aluminum nitrate, nickel nitrate, and titanium sulfate solutions can be adjusted to achieve controllable directional construction of the material based on different concentrations of fluoride or silicon in the water being treated. Furthermore, this material exhibits good stability, maintaining high selectivity and removal rate for fluoride and silicon in water even after repeated use. Silicic acid adsorbed on the electrode is decomposed into silica and water through an electrochemical reaction. This step requires appropriate potential and current density to ensure complete decomposition of the silicic acid. The decomposed silica is then separated from the solution by precipitation, thus achieving silicon ion removal. Simultaneously, heating reduces the surface tension of the water, which is beneficial for particle aggregation and flocculation. Lower surface tension reduces bubble formation and stability, improving coagulation efficiency. In the sedimentation zone, heating increases the water temperature, reducing water viscosity, decreasing resistance between particles, and accelerating particle settling. This invention, combining thermal enhancement and electroadsorption methods, achieves high sedimentation efficiency and has a low dependence on coagulants and flocculants.

[0022] The innovative aspects and beneficial effects of this invention are as follows:

[0023] I. This invention employs a spiral heating tube to introduce high-temperature steam, combining thermal enhancement with coagulation and sedimentation technology to accelerate chemical reactions, promote ion aggregation, improve reaction efficiency, reduce hydraulic retention time, and effectively enhance wastewater treatment efficiency. Simultaneously, it reduces water viscosity and surface tension, promoting particulate matter settling and improving impurity removal. This technology simplifies the treatment process and significantly improves efficiency.

[0024] II. This invention employs electroadsorption flocculation sedimentation technology, utilizing the synergistic effect of electroadsorption and flocculation processes to significantly improve the efficiency of silicon, fluoride, and hardness removal. During the electroadsorption flocculation sedimentation process, charged pollutants are adsorbed onto the electrode surface through electrostatic attraction. This effectively removes harmful substances such as silicon and fluoride ions from the water. Simultaneously, under the influence of an electric field, tiny suspended solids and other substances form larger flocs. These flocs are ultimately removed through sedimentation or filtration, thus purifying the water. Furthermore, by using thermal enhancement technology, supplemented by heating, the electroadsorption flocculation sedimentation process is accelerated, further improving sedimentation efficiency. The removal rate of silicon reaches 92%–98%, and the removal rate of fluoride exceeds 71%.

[0025] Third, this invention combines multiple chemical reactions with thermal enhancement and electroadsorption flocculation precipitation to achieve the simultaneous removal of substances such as silicon, fluorine, and calcium. This significantly reduces the required land area. Secondly, concentrating multiple treatments in the same reaction tank significantly reduces intermediate steps, thereby reducing the potential impact on the surrounding environment, lowering equipment and operating costs, and significantly improving reaction efficiency. This not only facilitates unified control and management but also reduces operational complexity. It not only efficiently removes contaminants but also significantly reduces the formation of silica scale in subsequent processes, effectively protecting equipment from damage, extending equipment lifespan, and reducing operating costs.

[0026] Fourth, the thermal energy used in this invention comes from waste heat generated during factory production. By recovering and reusing waste heat, not only can energy utilization efficiency be greatly improved and dependence on limited fresh energy sources be reduced, but also significant production costs can be saved for enterprises. This not only helps enterprises reduce operating costs and improve economic efficiency, but also further promotes the greening and cleanliness of industrial production. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the wastewater deep treatment device for simultaneous desiliconization and defluorination of the present invention.

[0028] 1 is the tank body, 1-1 is the sludge collection trough, 1-2 is the coagulation zone, 1-2-1 is the water inlet, 1-3 is the sedimentation zone, and 1-3-1 is the water outlet; 2 is the baffle, 3 is the electro-adsorption device, 4 is the agitator, 5 is the first spiral heating tube, 6 is the first inclined plate, 7 is the second inclined plate, 8 is the filter device, and 9 is the second spiral heating tube. Detailed Implementation

[0029] The beneficial effects of the present invention are verified using the following examples:

[0030] Example 1: The wastewater deep treatment device for simultaneous desiliconization and defluorination in this example consists of a tank 1, a baffle 2, an electro-adsorption device 3, a stirrer 4, a first spiral heating tube 5, a first inclined plate 6, a filter device 8, a second spiral heating tube 9, and a second inclined plate 7.

[0031] A sludge collection trough 1-1 is set at the center of the bottom of the pool body 1; the bottom of the pool body 1 is inclined to the sludge collection trough 1-1; a baffle 2 is set in the middle of the pool body 1, dividing the pool body 1 into a coagulation zone 1-2 and a sedimentation zone 1-3; an electro-adsorption device 3 is fixed at the lower end of the baffle 2; the electro-adsorption device 3 is opposite to the sludge collection trough 1-1 and has a gap so that water can flow from the coagulation zone 1-2 to the sedimentation zone 1-3.

[0032] An inlet 1-2-1 is provided on the upper side wall of the coagulation zone 1-2. The agitator 4 and the first spiral heating pipe 5 are located in the middle of the coagulation zone 1-2. The first inclined plate 6 is located at the bottom of the coagulation zone 1-2 and tilts towards the mud collection trough 1-1.

[0033] An outlet 1-3-1 is provided on the upper side wall of the sedimentation zone 1-3, a filter device 8 is provided below the outlet 1-3-1, a second spiral heating pipe 9 is provided in the middle of the sedimentation zone 1-3, and a second inclined plate 7 is provided at the bottom of the sedimentation zone 1-3 and inclined towards the sludge collection trough 1-1.

[0034] The electrodes of the electroadsorption device 3 are prepared by the following method: (1) 0.3 g of MAX phase powder Ti3C2T xAdd 6 mL of 7.1 mmol / L hydrofluoric acid aqueous solution and stir for 30 min. After centrifugation, wash the solid with distilled water until the pH of the supernatant reaches 5. Then, separate the layers by ultrasonication to obtain MXene dispersion; (2) Add 10 mL of 0.2 mol / L aluminum nitrate solution, 10 mL of 0.2 mol / L nickel nitrate solution and 10 mL of 0.2 mol / L titanium sulfate solution to the MXene dispersion. Adjust the pH to 8 during continuous stirring. After standing for 1 h, centrifuge and wash the solid obtained by centrifugation with distilled water and ethanol respectively. Dry in vacuum at 100℃. The electrode material was placed in the box for 12 hours and then placed in a high-temperature furnace. It was heated to 800℃ and held for 2 hours in an argon atmosphere to obtain the electrode material, which is TiNiAl-MXene nanopowder; (3) The electrode material, carbon black and PVDF emulsion with a mass percentage concentration of 11% were added to N-methylpyrrolidone (NMP) according to the mass ratio of TiNiAl-MXene nanopowder, carbon black and PVDF emulsion with a mass percentage concentration of 11% in an 8:1:1 ratio. The electrode material, carbon black and PVDF emulsion with a mass percentage concentration of 11% were added to N-methylpyrrolidone (NMP), ultrasonically treated for 10 minutes, and then coated onto the electrode plate. It was dried in a vacuum drying oven to obtain the electrode of the electroadsorption device, namely the TiNiAl-MXene material electrode. The electrode was prepared by using TiNiAl-MXene nanopowder as the electrode material. The specific surface area of ​​the MXene material was increased by modifying MXene with Ti, Ni and Al. The specific surface area of ​​the modified TiNiAl-MXene nanopowder reached 695m². 2 The / g ratio provides more adsorption sites, enhancing the adsorption capacity of MXene material electrodes for fluorine and silicon in water. Simultaneously, TiNiAl-MXene material electrodes exhibit high selective adsorption capacity for fluorine and silicon in water; even in the presence of interfering substances such as phosphorus and chlorine, the adsorption capacity for silicon and fluorine remains significantly higher than that for phosphorus and chlorine.

[0035] The apparatus of Example 1 was used to treat the effluent from the conditioning tank of the high-salinity wastewater section of a coal chemical plant. The water quality indicators were: pH: 7.40, Si: 43.04 mg / L. The specific method is as follows:

[0036] 1. The water from the regulating tank is introduced into the coagulation zone 1-2 through the inlet 1-2-1. At the same time, sodium aluminate is added to the coagulation zone 1-2 at a concentration of 610 mg / L, and PAC is added to the coagulation zone 1-2 at a concentration of 30 mg / L. After stirring for 10 minutes, high-temperature steam generated during industrial production is introduced into the first spiral heating tube to heat the water temperature in the coagulation zone 1-2 to 80°C. The water is then hydraulically retained for 30 minutes at a stirring speed of 200 rpm.

[0037] 2. When the wastewater that has been pre-treated in the coagulation zone 1-2 passes through the electro-adsorption device 3, it undergoes electro-adsorption flocculation and sedimentation. Then it enters the sedimentation zone 1-3, where the water is heated to 60°C by the second spiral heating tube 9 for enhanced sedimentation treatment for 30 minutes. After being filtered by the filtration device, it overflows and is discharged from the outlet 1-3-1. The sediment enters the sludge collection tank and is discharged under the promotion of the first inclined plate 6 and the second inclined plate 7.

[0038] In this embodiment, stirring and thermal intensification in the coagulation zone promote the hydrolysis of sodium aluminate in water, generating aluminum hydroxide precipitate, which can then adsorb silica in the water. PAC can trap silica in the water through adsorption bridging. Sodium aluminate combines with calcium and magnesium ions in the water to form insoluble hydroxide precipitates, thereby reducing water hardness. In the sedimentation zone, due to the existence of a temperature gradient field, particles are subjected to thermally induced migration forces, moving from the high-temperature side to the low-temperature side. The electroadsorption device performs adsorption on the electrode surface, which can be the adsorption of charged ions or molecules, or the formation of an electric double layer. During electroadsorption, charged pollutants are adsorbed onto the electrode surface through electrostatic attraction, or they are migrated to the electrode surface through electrophoresis, electroosmosis, etc. This adsorption can effectively reduce the concentration of pollutants in the water. Under the action of an electric field, colloidal particles or tiny suspended matter form larger flocs or particles through charge neutralization, aggregation, or bridging, significantly improving the sedimentation effect of flocs or particles in the water, thus effectively removing pollutants from the water.

[0039] In this embodiment, residual silicon was detected in the water flowing out from outlet 1-3-1. The amount of residual silicon was 3.02 mg / L, and the silicon removal rate reached 92.98%. A large amount of silicon existed in the form of flocculent precipitate, with good sedimentation performance, a clear mud-water interface, and easy separation.

[0040] Example 2: Using the apparatus of Example 1 to treat coal mine water, the water quality indicators of which are: pH: 6.80, fluoride: 3.5 mg / L, silica: 1 mg / L. The specific method is as follows:

[0041] 1. Coal mine water is introduced into coagulation zone 1-2 through inlet 1-2-1. At the same time, sodium aluminate is added to coagulation zone 1-2 at a mass ratio of NaAlO2:F = 17:1, and PAC is added to coagulation zone 1-2 at a concentration of 30 mg / L. After stirring for 10 minutes, the water temperature in coagulation zone 1-2 is heated to 80℃ using the first spiral heating tube. The water is then hydraulically retained for 30 minutes at a stirring speed of 200 rpm.

[0042] 2. When the wastewater that has been pre-treated in the coagulation zone 1-2 passes through the electro-adsorption device 3, it undergoes electro-adsorption flocculation and sedimentation. Then it enters the sedimentation zone 1-3, where the water is heated to 60°C by the second spiral heating tube 9 for enhanced sedimentation treatment for 30 minutes. After being filtered by the filtration device, it overflows and is discharged from the outlet 1-3-1. The sediment enters the sludge collection tank and is discharged under the promotion of the first inclined plate 6 and the second inclined plate 7.

[0043] In this implementation, in the coagulation zone, stirring and thermal intensification promote the hydrolysis of sodium aluminate in water, generating aluminum hydroxide precipitate, which can then adsorb silica in the water. PAC can trap silica in the water through adsorption bridging. Sodium aluminate reacts chemically with fluoride ions in water to form water-insoluble fluoride precipitates, and can also combine with calcium and magnesium ions in the water to form insoluble hydroxide precipitates, thereby reducing water hardness. In the sedimentation zone, due to the existence of a temperature gradient field, particles are subjected to thermally induced migration forces, moving from the high-temperature side to the low-temperature side. The electroadsorption device performs adsorption on the electrode surface, which can be the adsorption of charged ions or molecules, or the formation of an electric double layer. During electroadsorption, charged pollutants are adsorbed onto the electrode surface through electrostatic attraction, or they are migrated to the electrode surface through electrophoresis, electroosmosis, etc. This adsorption can effectively reduce the concentration of pollutants in the water. Simultaneously, under the influence of an electric field, colloidal particles or tiny suspended matter form larger flocs or particles through charge neutralization, aggregation, or bridging. This flocculation significantly improves sedimentation in water, effectively removing pollutants. In this embodiment, the residual fluoride content in the water flowing from outlet 1-3-1 was measured. The results showed that the residual fluoride content was <1 mg / L, with a removal rate of 71.43%, meeting the Class III fluoride discharge standard in the "Surface Water Environmental Quality Standard" (GB3838-2002). The silicon removal rate in the water flowing from outlet 1-3-1 reached 98%.

Claims

1. A wastewater deep treatment device for simultaneous desiliconization and defluorination, characterized in that, The device includes a pool body (1), a baffle (2), an electro-adsorption device (3), a stirrer (4), a first spiral heating tube (5), a first inclined plate (6), a second inclined plate (7), a filter device (8), and a second spiral heating tube (9). A sludge collection trough (1-1) is set at the center of the bottom of the pool body (1); the bottom of the pool body (1) is inclined to the sludge collection trough (1-1); a baffle (2) is set in the middle of the pool body (1) to divide the pool body (1) into a coagulation zone (1-2) and a sedimentation zone (1-3); an electro-adsorption device (3) is fixed at the lower end of the baffle (2); the electro-adsorption device (3) is opposite to the sludge collection trough (1-1) and has gaps so that water can flow from the coagulation zone (1-2) to the sedimentation zone (1-3); An inlet (1-2-1) is provided on the upper side wall of the coagulation zone (1-2), an agitator (4) and a first spiral heating pipe (5) are provided in the middle of the coagulation zone (1-2), and a first inclined plate (6) is provided at the bottom of the coagulation zone (1-2) and inclined towards the mud collection trough (1-1); An outlet (1-3-1) is provided on the upper side wall of the sedimentation zone (1-3), a filter device (8) is provided below the outlet (1-3-1), a second spiral heating pipe (9) is provided in the middle of the sedimentation zone (1-3), and a second inclined plate (7) is provided at the bottom of the sedimentation zone (1-3) and inclined towards the sludge collection tank (1-1).

2. The device for advanced treatment of sewage according to claim 1, characterized in that, The first spiral heating tube (5) and the second spiral heating tube (9) are heated by introducing steam.

3. The device for advanced treatment of sewage according to claim 2, characterized in that, The steam mentioned is waste heat generated during industrial production.

4. The device for advanced treatment of sewage according to claim 1 or 2, characterized in that, The method for preparing the electrodes of the electroadsorption device is as follows: (1) The MAX phase powder Ti3C2T x Add to hydrofluoric acid aqueous solution and stir for 30-60 min. After centrifugation, wash the solid with distilled water until the pH of the supernatant reaches between 4 and 6. Then, separate by ultrasonication to obtain MXene dispersion. (2) Add aluminum nitrate, nickel nitrate and titanium sulfate solution to MXene dispersion, and adjust the pH value to weak alkalinity during continuous stirring; after standing for 1 hour, centrifuge to separate the solid phase obtained by centrifugation, wash it with distilled water and ethanol respectively, vacuum dry it, and then place it in a high temperature furnace, heat it to 800-820℃ in an argon atmosphere and keep it for 2-3 hours to obtain the electrode material, which is TiNiAl-MXene nanopowder; (3) The electrode material, carbon black and PVDF emulsion with a mass percentage concentration of 10% to 11% are added to N-methylpyrrolidone in a mass ratio of (8 to 8.5):(1 to 1.2):

1. The mixture is ultrasonically treated for 10 to 20 minutes, then coated onto the electrode plate and dried in a vacuum drying oven to obtain the electrode of the electroadsorption device, namely the TiNiAl-MXene material electrode.

5. A method for simultaneous desiliconization and defluorination of wastewater using the apparatus described in claim 1, characterized in that... This method is performed in the following steps:

1. Wastewater containing silicon and / or fluoride is introduced into the coagulation zone (1-2) through the inlet (1-2-1). Sodium aluminate and coagulant are added to the coagulation zone (1-2) at the same time. Sodium aluminate is added at a mass ratio of NaAlO2:Si = (8~8.5):1, and the concentration of coagulant is 30~35mg / L. The water temperature in the coagulation zone (1-2) is heated to 80~85℃ using the first spiral heating tube. The water is hydraulically retained for 30~50min under the condition of stirring speed of 200~300rpm.

2. When the wastewater that has been pre-treated in the coagulation zone (1-2) passes through the electro-adsorption device (3), it undergoes electro-adsorption flocculation and sedimentation, and then enters the sedimentation zone (1-3). The water is heated to 60-65℃ by the second spiral heating tube (9) for enhanced sedimentation treatment for 30-50 minutes. After being filtered by the filtration device, it overflows from the outlet (1-3-1). The sediment enters the sludge collection tank and is discharged under the promotion of the first inclined plate (6) and the second inclined plate (7).

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