Method and device for synchronously treating fluorine and silicon in wastewater

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a synchronous treatment method and device for fluorine and silicon in wastewater, the fluorine and silicon wastewater treatment device comprises an outer cylinder and an inner cylinder, the inner cylinder is suspended in the outer cylinder, and an inner circulation passage is formed between the inner cylinder and the outer cylinder; a waste water feeding pipe and a crystal inducing agent feeding pipe are respectively arranged at the lower part of the outer barrel, outlets of the waste water feeding pipe and the crystal inducing agent feeding pipe are positioned below a lower barrel opening of the inner barrel, a water outlet pipe is arranged at the upper part of the outer barrel, and a return pipe is arranged between the water outlet pipe and the waste water feeding pipe; a granulation body discharge pipe is arranged at the bottom of the outer cylinder. Compared with the prior art, the purpose of efficiently and synchronously removing fluorine and silicon in the wastewater is achieved in the single-stage reactor by utilizing the modified composite seed crystal, designing the reflux of the recycled water and controlling the reflux ratio, the dosage of reagents is small, the process is short, the energy consumption is low, the formed granules are low in water content and high in solid-liquid separation efficiency, and the method is suitable for industrial production. Secondary treatment is not needed, and industrial application is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method and a device for simultaneously treating fluorine and silicon in wastewater. Background Art

[0002] At present, the commonly used methods for removing fluorine and silicon are mainly adsorption and precipitation. Among them, the chemical precipitation method is to add a certain amount of chemical reagents into fluorine and silicon wastewater to form fluoride with fluorine in the wastewater and silicate precipitate with silicon, or to use co-precipitation to adsorb fluoride ions and silicate ions, and then use filtration or natural sedimentation to separate the precipitate from water to achieve the purpose of removing silicon and fluorine. Although the chemical precipitation method is simple and has low processing costs, it has problems such as secondary pollution and large amount of reagents used. In addition, the sludge generated during the treatment process has defects such as high water content, slow sedimentation, and unsuitability for continuous discharge.

[0003] CN114349206A discloses a water treatment system for removing fluoride ions of different concentrations in water, comprising a chemical crystallization circulating granulation fluidized bed and a high-efficiency solid-liquid separation circulating granulation fluidized bed, wherein the water outlet at the top of the chemical crystallization circulating granulation fluidized bed is connected to a first water outlet pipe, and the water outlet at the top of the chemical crystallization circulating granulation fluidized bed is also connected to the water inlet at the bottom of the high-efficiency solid-liquid separation circulating granulation fluidized bed through an intermediate water outlet pipe, and the water outlet at the top of the high-efficiency solid-liquid separation circulating granulation fluidized bed is connected to the water inlet at the bottom of the high-efficiency solid-liquid separation circulating granulation fluidized bed. The outlet of the circulating granulation fluidized bed is connected to a second outlet pipe; it also includes a fluorine-containing raw water tank, which is connected to the water inlet at the bottom of the chemical crystallization circulating granulation fluidized bed through an inlet pipe with a centrifugal pump; the middle of the chemical crystallization circulating granulation fluidized bed is also connected to a sodium hydroxide dosing tank and / or a sodium dihydrogen phosphate dosing tank, and / or the bottom of the chemical crystallization circulating granulation fluidized bed is also connected to a calcium chloride dosing tank; the bottom water inlet of the circulating granulation fluidized bed with high solid-liquid separation is also connected to a PAC dosing tank and / or a PAM dosing tank. Compared with the existing chemical precipitation method, this system is simple to operate, saves time and effort, and has no secondary pollution, but it only has a good treatment effect on fluorine-containing wastewater below 10 mg / L, and cannot remove silicon in high-silicon wastewater at the same time.

[0004] Therefore, how to provide a method that is efficient, environmentally friendly, and low in resource consumption and can simultaneously remove fluorine and silicon from high-fluorine and high-silicon wastewater has become a problem that needs to be solved urgently. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned technical defects, the present invention provides a method and a treatment device for the simultaneous treatment of fluorine and silicon in wastewater, which utilizes modified composite crystal seeds and achieves the goal of efficient simultaneous removal of fluorine and silicon in wastewater in a single-stage reactor by designing the reflux of regenerated water and controlling the reflux ratio.

[0006] To achieve the above object, on the one hand, the present invention provides a fluorine-silicon wastewater treatment device, comprising an outer cylinder and an inner cylinder, wherein the inner cylinder is suspended and installed in the outer cylinder, and an internal circulation passage is formed between the inner cylinder and the outer cylinder;

[0007] A wastewater feed pipe and an inducer feed pipe are respectively provided at the lower part of the outer cylinder, and the outlets of the wastewater feed pipe and the inducer feed pipe are located below the lower cylinder opening of the inner cylinder. The wastewater feed pipe is used to introduce fluorine silicon wastewater and modified composite crystal seeds, and the inducer feed pipe is used to introduce the inducer;

[0008] A water outlet pipe is provided at the upper part of the outer cylinder for discharging recycled water;

[0009] A reflux pipe is provided between the water outlet pipe and the wastewater feed pipe;

[0010] A granulation body discharge pipe is arranged at the bottom of the outer cylinder for discharging the granulation body.

[0011] Furthermore, a tooth-shaped overflow weir is provided at the upper tube opening of the inner tube.

[0012] On the other hand, the present invention provides a method for simultaneously removing fluorine and silicon from wastewater, using the above-mentioned fluorine and silicon wastewater treatment device to treat wastewater, comprising the following steps:

[0013] S1. After adjusting the pH value of the fluorine-silicon wastewater to 6-10, the wastewater is introduced into the fluorine-silicon wastewater treatment device through the wastewater feed pipe;

[0014] In some specific embodiments, the pH adjusting agent for adjusting the pH of the fluorine-silicon wastewater includes sodium hydroxide solution and / or hydrochloric acid, and the fluorine-silicon wastewater is adjusted to 6-10, for example, 6, 7, 8, 9 or 10, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0015] In a preferred embodiment, the concentration of the sodium hydroxide solution is 1-5wt%, such as 1wt%, 2wt%, 3wt%, 4wt% or 5wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0016] In a preferred embodiment, the concentration of the hydrochloric acid is 12-20wt%, such as 12wt%, 14wt%, 16wt%, 18wt% or 20wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0017] S2. introducing the modified composite crystal seeds into the inner cylinder through the wastewater feed pipe until the filling height of the modified composite crystal seeds is 20-40% of the height of the inner cylinder;

[0018] In some specific embodiments, the filling height of the modified composite seed crystal is 20-40% of the inner cylinder height, such as 20%, 25%, 30%, 35% or 40%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0019] S3. introducing a crystal inducing agent into the fluorine-silicon wastewater treatment device through a crystal inducing agent feed pipe, controlling the molar ratio of the crystal inducing agent to the sum of fluoride ions and silicate ions in the fluorine-silicon wastewater to be (0.6-0.8):1, so that the crystal inducing agent reacts with the fluorine-silicon wastewater, and the generated precipitate adheres to the surface of the modified composite seed crystal to form a granulation body;

[0020] In some specific embodiments, in the fluorine-silicon wastewater treatment device, the molar ratio of the crystal inducing agent to the sum of fluoride ions and silicate ions in the fluorine-silicon wastewater is (0.6-0.8):1, for example, 0.6:1, 0.7:1 or 0.8:1, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0021] S4. A part of the regenerated water obtained after the reaction is discharged from the outlet pipe, and the other part is refluxed to the fluorine-silicon wastewater treatment device through the reflux pipe, and the reflux ratio of the regenerated water is controlled to be 10%-200%. This scheme aims at the difference in the content of fluoride ions and silicate ions in the wastewater, and by designing different reflux ratios, it helps to further improve the wastewater treatment efficiency.

[0022] Furthermore, in S1, the concentration of fluoride ions in the fluorine-silicon wastewater does not exceed 6000 mg / L, and the concentration of silicate ions does not exceed 4000 mg / L.

[0023] In some specific embodiments, in the fluorine-silicon wastewater, the concentration of fluoride ions does not exceed 6000 mg / L, for example, 10 mg / L, 50 mg / L, 100 mg / L, 500 mg / L, 1000 mg / L, 2000 mg / L, 3000 mg / L, 4000 mg / L, 5000 mg / L or 6000 mg / L, etc.; the concentration of silicate ions does not exceed 4000 mg / L, for example, 10 mg / L, 50 mg / L, 100 mg / L, 500 mg / L, 1000 mg / L, 2000 mg / L, 3000 mg / L or 4000 mg / L, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0024] Furthermore, the modified composite seed crystals include one or more of nucleophile modified seed crystals and ultrapure water activated seed crystals.

[0025] It is well known to those skilled in the art that conventional commercial modified composite seed crystals can further improve the removal efficiency of fluoride ions and silicate ions in wastewater after surface modification.

[0026] In some specific embodiments, the particle size of the modified composite seed crystal is 120-140 mesh, such as 120 mesh, 130 mesh or 140 mesh, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0027] Furthermore, the nucleophile-modified seed crystals are prepared by the following method: dispersing the seed crystals in a nucleophile solution, stirring for 6-12 hours in an atmosphere of 60-80° C., taking out, washing with water, and then drying.

[0028] Furthermore, the seed crystal is one or more of dolomite, quartz sand, and brucite; in a preferred embodiment, it is selected from dolomite and / or quartz sand.

[0029] Further, the nucleophilic agent comprises one or more of thiol, amide or phosphate; in a preferred embodiment, it is selected from a combination of thiol and amide, and a combination of amide and phosphate;

[0030] Wherein, the mercaptan includes but is not limited to tert-butyl mercaptan, 2-mercaptomercaptan, and methyl mercaptan;

[0031] Amides include but are not limited to propionamide, acetamidobenzene, and oxalamide;

[0032] Phosphates include, but are not limited to, sodium phosphate, sodium pyrophosphate, and sodium tripolyphosphate.

[0033] Furthermore, the preparation method of the ultrapure water-activated composite seed crystals includes: washing dolomite and / or quartz sand with ultrapure water, then drying, and then soaking in ultrapure water for 12-24 hours. The soaking time is selected to be 12 hours, 16 hours, 20 hours or 24 hours, etc., but is not limited to the listed values. Other values ​​not listed in this range are also applicable.

[0034] Furthermore, in S3, the crystal-inducing agent includes one or more of calcium chloride, magnesium chloride or calcium hydroxide, and a crystal-inducing agent aqueous solution with a concentration of 30-45wt% is introduced into the fluorine silicon wastewater treatment device.

[0035] In some specific embodiments, the crystal inducing agent is selected from a combination of calcium chloride and magnesium chloride, a combination of calcium chloride and calcium hydroxide, and the like.

[0036] In some specific embodiments, the concentration of the inducing agent in the solution is 30-45wt%, such as 30wt%, 35wt%, 40wt% or 45wt%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0037] Further, in S4, when the concentration of fluoride ions is 0-1000 mg / L and the concentration of silicate ions is 0-1000 mg / L, the reflux ratio of the regenerated water is 10%-20%;

[0038] In some specific embodiments, the reflux ratio is selected to be 10%, 15%, 20%, etc., but is not limited to the listed values.

[0039] Other values ​​not listed within this range also apply.

[0040] When the concentration of fluoride ions is 1000-3000 mg / L and the concentration of silicate ions is 1000-2000 mg / L, the reflow ratio of recycled water is 100%-150%;

[0041] In some specific embodiments, the reflux ratio is selected as 100%, 110%, 120%, 130%, 140%, 150%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0042] When the concentration of fluoride ions is 3000-6000 mg / L and the concentration of silicate ions is 2000-4000 mg / L, the reflux ratio of the regenerated water is 150%-200%.

[0043] In some specific embodiments, the reflux ratio is selected as 150%, 160%, 170%, 180%, 190%, 200%, etc., but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] 1. The present invention adopts nuclear crystal granulation technology, utilizes modified composite crystal seeds, and realizes efficient and simultaneous removal of fluorine and silicon in wastewater in a single-stage reactor by designing the reflux of recycled water and controlling the reflux ratio;

[0046] 2. The granules formed by the present invention have low moisture content and high solid-liquid separation efficiency, and no secondary treatment is required;

[0047] 3. The present invention has small reagent usage, low energy consumption, short process, small equipment footprint, and low cost, which is conducive to industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a structural schematic diagram of the fluorine silicon wastewater treatment device of the present invention;

[0049] Figure 2 is the SEM image of the modified dolomite of Example 1;

[0050] Figure 3is a SEM image of the granules of Example 1;

[0051] Figure 4 This is the element distribution diagram of the granules of Example 1. DETAILED DESCRIPTION

[0052] In order to make those skilled in the art better understand the technical scheme of the present invention, the present invention is described in detail below in conjunction with specific embodiments. The experimental methods for which specific conditions are not indicated in the following examples are usually carried out under normal conditions or according to the conditions recommended by the manufacturer. The test materials used in the following examples, unless otherwise specified, are purchased from conventional biochemical reagent stores. Unless otherwise specified, percentages and parts are calculated by weight. Unless otherwise defined, all professional and scientific terms used in the text have the same meaning as those familiar to those skilled in the art. In addition, any method and material similar to or equal to the recorded content can all be applied to the present invention. The preferred implementation methods and materials described in the text are only for demonstration purposes.

[0053] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0054] Figure 1 It is a schematic diagram of the structure of a fluorine-silicon wastewater treatment device shown in some embodiments of the present invention.

[0055] like Figure 1 As shown, the fluorine silicon wastewater treatment device comprises an outer cylinder 1 and an inner cylinder 2, wherein the inner cylinder 2 is suspended and installed in the outer cylinder 1, an internal circulation passage is formed between the inner cylinder 2 and the outer cylinder 1, and a toothed overflow weir 8 is arranged at the upper cylinder mouth of the inner cylinder 2; a wastewater feed pipe 3 and a crystal inducing agent feed pipe 4 are respectively arranged at the lower part of the outer cylinder 1, and the outlets of the wastewater feed pipe 3 and the crystal inducing agent feed pipe 4 are located below the lower cylinder mouth of the inner cylinder 2, and the wastewater feed pipe 3 It is used to introduce fluorine silicon wastewater and modified composite crystal seeds, and the inducing agent feed pipe 4 is used to introduce the inducing agent; a water outlet pipe 5 is provided on the upper part of the outer cylinder 1 for discharging recycled water; a reflux pipe 6 is provided between the water outlet pipe 5 and the wastewater feed pipe 3; a granulation body discharge pipe 7 is provided at the bottom of the outer cylinder 1 for discharging the granulation body; solenoid valves are installed on the wastewater feed pipe 3, the inducing agent feed pipe 4, the water outlet pipe 5, the reflux pipe 6 and the granulation body discharge pipe 7.

[0056] Based on the fluorine-silicon wastewater treatment device of the present invention, the pH value of the fluorine-silicon wastewater with a fluoride ion concentration not exceeding 6000 mg / L and a silicate ion concentration not exceeding 4000 mg / L is adjusted to 6-10, and the modified composite crystal seeds and the fluorine-silicon wastewater are introduced into the fluorine-silicon wastewater treatment device together through a water pump. When the filling height of the modified composite crystal seeds reaches 20-40% of the height of the inner cylinder 2, the feeding of the modified composite crystal seeds is stopped; the crystal inducing agent is prepared into an aqueous solution with a concentration of 30-45wt% and introduced into the fluorine-silicon wastewater treatment device through the crystal inducing agent feeding pipe 4, and the crystal inducing agent and the fluorine-silicon wastewater are controlled. The molar ratio of the sum of fluoride ions and silicate ions in the wastewater is (0.6-0.8):1; according to the difference in the content of fluoride ions and silicate ions in the wastewater, the reflux ratio of the regenerated water is controlled to be 10%-200%, and the fluorine-silicon wastewater flows in the internal circulation passage in the fluorine-silicon wastewater treatment device, so that the crystal inducer reacts with the fluorine-silicon wastewater, and the generated precipitate adheres to the surface of the modified composite seed crystal to form granules, and a part of the regenerated water after the reaction is discharged from the outlet pipe, and the other part is refluxed to the fluorine-silicon wastewater treatment device through the reflux pipe 6, and the granules generated by the reaction are discharged through the granule discharge pipe.

[0057] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments and appended tables. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0058] Example 1

[0059] This embodiment provides a method for simultaneously treating fluorine and silicon in wastewater, the method comprising the following steps:

[0060] (1) filling the inner cylinder 2 of a fluorine-silicon wastewater treatment device with an outer cylinder 1 of 2 m in height and an inner cylinder 2 of 1.2 m in height with modified dolomite having a particle size of 120 meshes, wherein the filling height of the modified dolomite is 35% of the height of the inner cylinder 2;

[0061] The preparation method of the modified dolomite comprises: washing the dolomite with ultrapure water, then drying it, and then soaking it in ultrapure water for 20 hours;

[0062] (2) The fluoride ion concentration in the fluorine-silicon wastewater is 3000 mg / L, the silicate ion concentration is 2000 mg / L, and the pH is adjusted to 8 using 3 wt% sodium hydroxide;

[0063] Passing the pH-adjusted fluorine-silicon wastewater into the fluorine-silicon wastewater treatment device to make the modified dolomite therein fluidized;

[0064] Then, a 30 wt% calcium chloride solution is introduced into the fluorine-silicon wastewater treatment device to make the calcium chloride react with the fluoride ions and the silicate ions, and the generated precipitates adhere to the surface of the modified dolomite to form granules;

[0065] Wherein, in the fluorine-silicon wastewater treatment device, the molar ratio of calcium chloride to the sum of fluoride ions and silicate ions in the fluorine-silicon wastewater is controlled to be 0.6:1;

[0066] Part of the regenerated water obtained after the reaction is discharged from the upper part of the fluorine-silicon wastewater treatment device, and the other part is refluxed into the fluorine-silicon wastewater treatment device, and the reflux ratio is controlled to be 100%; the obtained granules are discharged from the bottom of the fluorine-silicon wastewater treatment device.

[0067] In this embodiment, the SEM image of the modified dolomite is as follows: Figure 2 As shown. Figure 2 It can be seen that before granulation, the surface of the seed crystal is smooth, and there are step-shaped kinks in some areas, which provide active sites for the subsequent attachment of the crystal nucleus; after wastewater treatment, a variety of precipitates are attached to the surface of the modified dolomite to form granules. The SEM image of the obtained granules (such as Figure 3 ). In addition, the element distribution diagram of the obtained granules is shown in Figure 4 As shown by Figure 4 It can be seen that during the granulation process, silicon and fluorine in the wastewater nucleate and grow in the form of calcium silicate and calcium fluoride respectively, adhere to the surface of the seed crystals, and form a dense granulation body.

[0068] Example 2

[0069] This embodiment provides a method for simultaneously treating fluorine and silicon in wastewater, the method comprising the following steps:

[0070] (1) Filling the inner cylinder 2 of a fluorine-silicon wastewater treatment device with an outer cylinder 1 of 2 m in height and an inner cylinder 2 of 1.2 m in height with modified dolomite having a particle size of 125 mesh, wherein the filling height of the modified dolomite is 22% of the height of the inner cylinder 2;

[0071] The preparation method of the modified dolomite comprises: dispersing the dolomite in a tert-butyl mercaptan solution, stirring for 6-12 hours in an atmosphere of 60-80° C., taking out, washing with water and then drying.

[0072] (2) The fluoride ion concentration in the fluorine-silicon wastewater is 4000 mg / L, and the silicate ion concentration is 3000 mg / L. The pH value is adjusted to 6 using 15 wt% hydrochloric acid;

[0073] Passing the pH-adjusted fluorine-silicon wastewater into the fluorine-silicon wastewater treatment device to make the modified dolomite therein fluidized;

[0074] Then, a 32 wt% calcium chloride solution is introduced into the fluorine-silicon wastewater treatment device to make the calcium chloride react with the fluoride ions and the silicate ions, and the generated precipitates adhere to the surface of the modified dolomite to form granules;

[0075] Wherein, in the fluorine-silicon wastewater treatment device, the molar ratio of calcium chloride to the sum of fluoride ions and silicate ions in the fluorine-silicon wastewater is controlled to be 0.8:1;

[0076] Part of the regenerated water obtained after the reaction is discharged from the upper part of the fluorine silicon wastewater treatment device, and the other part is refluxed into the fluorine silicon wastewater treatment device, and the reflux ratio is controlled to be 100% until the granules are discharged from the bottom of the fluorine silicon wastewater treatment device.

[0077] Example 3

[0078] This embodiment provides a method for simultaneously treating fluorine and silicon in wastewater, the method comprising the following steps:

[0079] (1) filling the inner cylinder 2 of a fluorine-silicon wastewater treatment device with an outer cylinder 1 of 2 m in height and an inner cylinder 2 of 1.2 m in height with modified quartz sand having a particle size of 140 meshes, wherein the filling height of the modified quartz sand is 25% of the height of the inner cylinder 2;

[0080] The preparation method of the modified quartz sand comprises: dispersing quartz sand in a nucleophilic reagent solution, stirring for 6 hours in an atmosphere of 60° C., taking out, washing with water and then drying.

[0081] (2) The fluoride ion concentration in the fluorine-silicon wastewater is 6000 mg / L, and the silicate ion concentration is 3500 mg / L. The pH value is adjusted to 7 using 12 wt% hydrochloric acid;

[0082] Passing the pH-adjusted fluorine-silicon wastewater into the fluorine-silicon wastewater treatment device to make the modified dolomite therein fluidized;

[0083] Then, 40 wt% of calcium hydroxide liquid is passed into the fluorine-silicon wastewater treatment device to make the calcium hydroxide react with fluoride ions and silicate ions, and the generated precipitate adheres to the surface of the modified quartz sand to form a granulated body;

[0084] Wherein, in the fluorine-silicon wastewater treatment device, the molar ratio of calcium hydroxide to the sum of fluoride ions and silicate ions in the fluorine-silicon wastewater is controlled to be 0.8:1;

[0085] Part of the regenerated water obtained after the reaction is discharged from the upper part of the fluorine-silicon wastewater treatment device, and the other part is refluxed into the fluorine-silicon wastewater treatment device, and the reflux ratio is controlled to be 200%; the obtained granules are discharged from the bottom of the fluorine-silicon wastewater treatment device.

[0086] Example 4

[0087] This embodiment provides a method for simultaneously treating fluorine and silicon in wastewater, the method comprising the following steps:

[0088] (1) filling the inner cylinder 2 of a fluorine-silicon wastewater treatment device with an outer cylinder 1 of 2 m in height and an inner cylinder 2 of 1.2 m in height with modified quartz sand having a particle size of 130 meshes, wherein the filling height of the modified quartz sand is 35% of the height of the inner cylinder 2;

[0089] The preparation method of the modified quartz sand comprises: dispersing quartz sand in a sodium phosphate solution, stirring for 12 hours in an atmosphere of 80° C., taking out, washing, and drying.

[0090] (2) The fluoride ion concentration in the fluorine-silicon wastewater is 500 mg / L, and the silicate ion concentration is 400 mg / L. The pH value is adjusted to 8 using 4 wt% sodium hydroxide;

[0091] Passing the pH-adjusted fluorine-silicon wastewater into the fluorine-silicon wastewater treatment device to make the modified dolomite therein fluidized;

[0092] Then, a 45 wt% magnesium chloride solution is introduced into the fluorine-silicon wastewater treatment device to make the magnesium chloride react with the fluoride ions and the silicate ions, and the generated precipitates adhere to the surface of the modified quartz sand to form granules;

[0093] Wherein, in the fluorine-silicon wastewater treatment device, the molar ratio of magnesium chloride to the sum of fluoride ions and silicate ions in the fluorine-silicon wastewater is controlled to be 0.6:1;

[0094] Part of the regenerated water obtained after the reaction is discharged from the upper part of the fluorine-silicon wastewater treatment device, and the other part is refluxed into the fluorine-silicon wastewater treatment device, and the reflux ratio is controlled to be 10%; the obtained granules are discharged from the bottom of the fluorine-silicon wastewater treatment device.

[0095] Example 5

[0096] This embodiment provides a method for simultaneously treating fluorine and silicon in wastewater. The method refers to the method in Example 1, with the only difference being that the reflux ratio of the obtained regenerated water is 100%.

[0097] Comparative Example 1

[0098] This comparative example provides a method for simultaneously treating fluorine and silicon in wastewater. The method refers to the method in Example 1, with the only difference being that the seed crystal used is dolomite without modification.

[0099] Comparative Example 2

[0100] This comparative example provides a method for the simultaneous treatment of fluorine and silicon in wastewater. The method refers to the method in Example 1, with the only difference being that the resulting regenerated water is not partially refluxed but is directly discharged in its entirety.

[0101] Comparative Example 3

[0102] This comparative example provides a method for the simultaneous treatment of fluorine and silicon in wastewater. The method refers to the method in Example 1, with the only difference being that the seed crystal used is dolomite without modification; at the same time, the obtained regenerated water is not partially refluxed but is directly discharged in its entirety.

[0103] The concentrations of fluoride ions and silicate ions in the regenerated water discharged from the fluorine-silicon wastewater treatment device of Examples 1-6 and Comparative Examples 1-3 were measured, and their removal rates were calculated. The results are shown in Table 1.

[0104] Table 1

[0105]

[0106] As can be seen from Table 1, the present invention adopts nuclear crystal granulation technology, utilizes modified composite crystal seeds, and optimizes the reflux ratio for fluorine and silicon wastewaters of different concentrations to enhance the fluorine and silicon removal effect, so that the fluoride ion removal rate reaches more than 99.6%, and the silicate ion removal rate reaches more than 99.5%, thereby realizing efficient simultaneous removal of fluorine and silicon in wastewater in a single-stage reactor.

[0107] Finally, it should be noted that the above description is only a preferred embodiment of the present invention, and those skilled in the art will

[0108] In light of the present invention, various similar expressions can be made without violating the spirit and claims of the present invention, and such changes all fall within the protection scope of the present invention.

Claims

1. Fluorine and silicon wastewater treatment device, characterized by: The invention comprises an outer cylinder (1) and an inner cylinder (2), wherein the inner cylinder (2) is suspended and installed in the outer cylinder (1), and an internal circulation passage is formed between the inner cylinder (2) and the outer cylinder (1); a wastewater feed pipe (3) and a crystal inducing agent feed pipe (4) are respectively arranged at the lower part of the outer cylinder (1), and the outlets of the wastewater feed pipe (3) and the crystal inducing agent feed pipe (4) are located below the lower cylinder opening of the inner cylinder (2); a water outlet pipe (5) is arranged at the upper part of the outer cylinder (1), and a reflux pipe (6) is arranged between the water outlet pipe (5) and the wastewater feed pipe (3); and a granulation body discharge pipe (7) is arranged at the bottom of the outer cylinder (1).

2. The fluorine-silicon wastewater treatment device according to claim 1, characterized in that: A toothed overflow weir (8) is provided at the upper opening of the inner cylinder (2).

3. A method for simultaneously removing fluorine and silicon from wastewater, characterized in that: The fluorine-silicon wastewater treatment device according to claim 1 is used to treat wastewater, comprising the following steps: S1. After the pH value of the fluorine-silicon wastewater is adjusted to 6-10, it is introduced into the fluorine-silicon wastewater treatment device through the wastewater feed pipe (3), and the water flows in the internal circulation path; S2. introducing the modified composite crystal seeds into the inner cylinder (2) through the wastewater feed pipe (3) until the filling height of the modified composite crystal seeds is 20-40% of the height of the inner cylinder (2); S3. introducing a crystal inducing agent into the fluorine-silicon wastewater treatment device through a crystal inducing agent feed pipe (4), controlling the molar ratio of the crystal inducing agent to the sum of fluoride ions and silicate ions in the fluorine-silicon wastewater to be (0.6-0.8):1, so that the crystal inducing agent reacts with the fluorine-silicon wastewater, and the generated precipitate adheres to the surface of the modified composite seed crystal to form a granulated body; S4. A portion of the regenerated water obtained after the reaction is discharged from the outlet pipe (5), and the other portion is refluxed to the fluorine silicon wastewater treatment device through the reflux pipe (6), and the reflux ratio of the regenerated water is controlled to be 10%-200%.

4. The method according to claim 3, characterized in that In S1, the concentration of fluoride ions in the fluorine-silicon wastewater does not exceed 6000 mg / L, and the concentration of silicate ions does not exceed 4000 mg / L.

5. The method according to claim 3, characterized in that: The modified composite seed crystals include one or more of nucleophile modified seed crystals and ultrapure water activated seed crystals.

6. The method according to claim 5, characterized in that: The nucleophile-modified seed crystals are prepared by the following method: dispersing the seed crystals in a nucleophile solution, stirring for 6-12 hours in an atmosphere of 60-80° C., taking out, washing with water, and drying.

7. The method according to claim 5, characterized in that: The ultrapure water activated seed crystals are prepared by the following method: the seed crystals are washed with ultrapure water, then dried, and then soaked in ultrapure water for 12-24 hours.

8. The method according to claim 6 or 7, characterized in that: The seed crystal is one or more of dolomite, quartz sand, and brucite; the nucleophilic reagent includes one or more of thiol, amide, or phosphate.

9. The method according to claim 3, characterized in that In S3, the crystal inducing agent includes one or more of calcium chloride, magnesium chloride or calcium hydroxide, and the crystal inducing agent aqueous solution with a concentration of 30-45wt% is introduced into the fluorine silicon wastewater treatment device.

10. The method according to claim 7, characterized in that In S4, when the concentration of fluoride ions is 0-1000 mg / L and the concentration of silicate ions is 0-1000 mg / L, the reflux ratio of the regenerated water is 10%-20%; When the concentration of fluoride ions is 1000-3000 mg / L and the concentration of silicate ions is 1000-2000 mg / L, the reflow ratio of recycled water is 100%-150%; When the concentration of fluoride ions is 3000-6000 mg / L and the concentration of silicate ions is 2000-4000 mg / L, the reflux ratio of the regenerated water is 150%-200%.

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