A micro-nano cabin enhanced fluorine removal and recovery system

Abstract

The present invention discloses a micro-nano cabin enhanced fluorine removal and fluorine recovery system, which belongs to the field of sewage treatment. The system includes a grain discharge module, a micro-nano cabin reaction module and a effluent discharge module from bottom to top. The grain discharge module includes a grain filter screen, a filtrate collection pool and a grain collection area; the micro-nano cabin reaction module includes a grain temporary storage area, a water inlet area and a reaction area. The lower part of the grain temporary storage area is connected to the grain discharge module. The water inlet area includes a raw water inlet pipe, a precipitant dosing device, a sulfuric acid and sodium hydroxide dosing device. After adjusting to the optimal reaction conditions, it enters the multi-layer micro-nano cabin reaction area to react and obtain calcium fluoride grains; the effluent discharge module includes an inner cylinder and an outer cylinder. The effluent from the inner cylinder flows to the outer cylinder through an overflow weir and is discharged. The present invention makes full use of the structure and reaction characteristics of each module, adopts a micro-nano cabin to form a local enhanced reaction process, and has the advantages of high fluorine removal efficiency, low dosage of reagents, high purity recovery, etc., and can realize efficient treatment of fluorine-containing wastewater and fluorine resource recovery.

Description

Technical Field

[0001] The present invention belongs to the field of sewage treatment, and in particular relates to a micro-nano chamber enhanced fluorine removal and recovery system. Background Art

[0002] Wastewater discharged from the photovoltaic industry usually contains high concentrations of fluoride, which can cause great harm to human health and the environment if discharged directly.

[0003] At present, the main wastewater defluoridation processes include adsorption, precipitation, ion exchange, and membrane treatment technologies. Among them, the adsorption method is mostly used to treat low-concentration fluoride-containing wastewater, but it has problems such as limited adsorption capacity, complicated adsorbent regeneration process, easy secondary pollution, and low industrial economic efficiency. The precipitation method is the most widely used in wastewater treatment. It is simple and convenient to operate, with low operating costs. It can be used to treat high-concentration fluoride-containing wastewater, but it has problems such as large sludge production, high water content, low calcium fluoride content, and difficulty in recycling fluorine resources. The ion exchange resin method has a simple process and good reuse effect, but it has problems such as high resin prices and high regeneration costs, which limit its industrial application. Membrane treatment technology has the advantages of reducing the wastewater treatment volume of subsequent process units and increasing the wastewater reuse rate. However, it should be pointed out that a pretreatment unit must be set up at the front end of membrane treatment technology, which leads to increased investment costs. In addition, there are also problems such as high operating and maintenance costs and weak resistance to acid and alkali corrosion. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a micro-nano chamber enhanced fluorine removal and recovery system.

[0005] The specific technical methods provided by the present invention are as follows:

[0006] The present invention provides a micro-nano cabin enhanced fluorine removal and recovery system, comprising a grain discharge module, a micro-nano cabin reaction module and a water discharge module connected in sequence from bottom to top;

[0007] The bottom of the grain discharge module is divided into a grain collection area and a fluorine-containing filtrate collection area. The grain collection area is used to collect drained calcium fluoride grains. It has a conical bottom and a discharge port connected to an external pipe, facilitating the collection of grains and their discharge from the bottom discharge port into the calcium fluoride grain collector. The fluorine-containing filtrate collection area has a drain pipe at the bottom, which drains to the fluorine-containing raw water collection tank and re-enters the device for fluoride removal. A grain screen is placed above the fluorine-containing filtrate collection area, and a row of air blowing pipes is installed on the right wall of the filter. By adjusting the gas flow rate, the surface moisture of the calcium fluoride grains on the filter can be dried or the grains can be blown off the filter into the grain collection area.

[0008] The bottom of the micro-nano cabin reaction module is a temporary storage area for the grains. It has a conical structure and is equipped with a pressure sensor and a discharge valve. When the calcium fluoride grains falling from the micro-nano cabin reaction module reach a certain weight, the bottom discharge valve automatically opens, the raw water inlet valve closes, and the calcium fluoride grains enter the grain discharge module. The middle part of the micro-nano cabin reaction module is a cylindrical structure, with a raw water inlet pipe, a precipitant dosing device, a sulfuric acid dosing device, and a sodium hydroxide dosing device on the bottom side. After the raw water and the reagents are fully mixed, they enter the multi-layer micro-nano cabin reaction area. The micro-nano cabin is composed of two Y-shaped thin sheets on the left and right, with calcium fluoride seeds placed in the middle. The Y-shaped thin sheets are made of elastic material. When the reacted calcium fluoride grains reach a certain weight, the grains escape from the micro-nano cabin and automatically fall into the bottom of the micro-nano cabin reaction module. At the same time, the bottom of the micro-nano cabin reaction module is also equipped with a vacuum exhaust device, which can assist the calcium fluoride grains to escape from the micro-nano cabin by vacuuming.

[0009] The effluent discharge module is a cavity structure that gradually expands at the top and is divided into an inner tube and an outer tube. The inner tube and the outer tube are separated by an overflow weir. The inner tube is provided with an online pH meter, which is linked to the sulfuric acid dosing pump and liquid alkali dosing pump at the bottom of the micro-nano chamber reaction module to adjust the pH of the reaction in the micro-nano chamber; a drain outlet, a reflux outlet and an online fluoride ion meter are provided at the bottom of the outer tube. The fluoride ion meter is used to monitor the fluoride ion concentration in the effluent water. The drain outlet valve and the reflux outlet valve are linked to the online fluoride ion meter. When the fluoride ion concentration in the water of the outer tube exceeds the discharge limit, the drain outlet valve is closed, the reflux outlet valve is opened, and the effluent flows from the reflux pipe into the raw water collection tank, mixes with the raw water and re-enters the device for fluoride removal treatment; when the fluoride ion concentration in the water of the outer tube is lower than the discharge limit, the drain outlet valve is opened, the reflux outlet valve is closed, and the effluent flows out from the drain pipe.

[0010] Preferably, the grain collection area is located in the right 1 / 3 area of the grain discharge module, and the fluorine-containing filtrate collection area is located in the left 2 / 3 area of the grain discharge module. The filtrate in the fluorine-containing filtrate collection area can flow back to the raw water collection tank.

[0011] Preferably, two layers of filter screens are placed above the fluorine-containing filtrate collection area, with a spacing of 100-200 mm. The upper filter screen is tilted downward by 15° and has a pore size of 3-5 mm. The lower filter screen is tilted downward by 30° and has a pore size of 1-2 mm.

[0012] Preferably, the wastewater reaction conditions include: the flow rate of the water inlet is controlled within a range of 30 to 50 L / min, and the flow rate of the precipitant inlet is controlled within a range of 5 to 10 L / min.

[0013] Preferably, the multi-layer micro-nano cabin is distributed at 1 / 4 to 3 / 4 of the micro-nano cabin reaction module, and the angle between the two Y-shaped sheets constituting the micro-nano cabin is 90° to 100°.

[0014] Preferably, the diameter of the seed crystal in the micro-nano chamber is in the range of 100 μm to 200 μm, and the volume ratio of the micro-nano chamber to the seed crystal is in the range of 200 to 300.

[0015] Preferably, in the water outlet discharge module, a drain port and a return port are provided on the side wall of the outer cylinder, and the return port is located at a height of 1 / 2 to 2 / 3 below the drain port.

[0016] Preferably, the molar ratio of calcium to fluorine in the fluorine-containing wastewater and the precipitant liquid is 0.5 to 1.0, and the reaction pH is maintained in the range of 6 to 8.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1) The device consists of a crystal discharge module, a micro-nano chamber reaction module, and a water discharge module from bottom to top. With the micro-nano chamber reaction module as the core, it recovers fluorine precipitation resources downward and discharges qualified wastewater upward. The functions support each other, the structure is compact, and the footprint is small.

[0019] 2) By adding calcium fluoride seed crystals, the fluoride ions and calcium ions in the wastewater are quickly precipitated on the surface of the seed crystals in the form of calcium fluoride crystals, thereby improving the fluoride removal efficiency.

[0020] 3) The micro-nano cabin structure is used to localize the reaction area, strengthen the crystallization reaction, reduce seed loss, improve the efficiency of reagent utilization, and reduce the cost of fluorine removal.

[0021] 4) The calcium fluoride crystals generated by the reaction in the micro-nano chamber are of high purity, which can improve the resource recovery and utilization potential of fluorine precipitates.

[0022] 5) The device has a deep defluoridation effect on wastewater, ensuring that fluoride ions in the effluent are stably discharged in compliance with the standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural diagram of this system;

[0024] Figure 2 This is a structural diagram of a micro-nano cabin;

[0025] In the figure: grain discharge module I, micro-nano cabin reaction module II, effluent discharge module III, raw water inlet pipeline 1, precipitant dosing device 2, sulfuric acid dosing device 3, sodium hydroxide dosing device 4, discharge valve 5, grain screen 6, filtrate collection area 7, filtrate reflux pipe 8, grain collection area 9, micro-nano cabin 10, thin sheet 11, calcium fluoride seed crystal 12, overflow weir 13, online pH meter 14, online fluoride ion meter 15, drain valve 16, reflux valve 17, raw water collection tank 18, vacuum pump 19, air blowing pipe 20, grain discharge port 21, calcium fluoride grain collector 22, pressure sensor 23, raw water inlet valve 24, effluent reflux pipe 25, inner cylinder 26, outer cylinder 27, multi-layer micro-nano cabin reaction area 28, drain port 29, reflux port 30, drain pipe 31, grain temporary storage area 32. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the embodiments described below are only a part of the embodiments of the present invention, and the technical features of each embodiment of the present invention can be combined and adjusted without conflict.

[0027] like Figure 1 As shown, the present invention provides a micro-nano chamber enhanced fluorine removal device, which includes a grain discharge module I, a micro-nano chamber reaction module II, and a water discharge module III connected in sequence from bottom to top. The structure and connection method of each device are described in detail below.

[0028] The bottom of the grain discharge module 1 is divided into two collection areas. The right 1 / 3 is the grain collection area 9, which collects the drained calcium fluoride grains. The grain collection area 9 has a conical bottom and a discharge port 21 connected to an external pipe, facilitating the collection of the grains and their discharge from the bottom discharge port 21 into the calcium fluoride grain collector 22. The left 2 / 3 is the fluorine-containing filtrate collection area 7. A drain pipe 8 is installed at the bottom of the fluorine-containing filtrate collection area 7, which drains to the fluorine-containing raw water collection tank 18 and re-enters the device for defluoridation. Two layers of filter screens 6 are placed above the fluorine-containing filtrate collection area 7, with a spacing of 100-200mm. The upper filter screen is tilted downward at 15° and has a pore size of 3-5mm. The lower filter screen is tilted downward at 30° and has a pore size of 1-2mm. A row of air blowing pipes 20 are installed on the right wall of the filter screen to dry the surface moisture of the calcium fluoride grains on the filter screen and blow the grains off the filter screen into the grain collection area 9.

[0029] The bottom of the micro-nano cabin reaction module II is conical and is equipped with a pressure sensor 23 and a discharge valve 5. When the calcium fluoride crystals dropped from the micro-nano cabin reaction module accumulate to a certain weight, the bottom discharge valve 5 automatically opens, the raw water inlet valve 24 closes, and the calcium fluoride crystals enter the crystal discharge module I. The middle part of the micro-nano cabin reaction module II is a cylindrical structure, and the lower side is equipped with a raw water inlet pipe 1, a precipitant dosing device 2, a sulfuric acid dosing device 3, and a sodium hydroxide dosing device 4. The flow rate of the wastewater inlet is controlled to be 30~50 L / min, and the flow rate of the precipitant inlet is 5~10 L / min. After the raw water and the reagent are fully mixed, they enter the multi-layer micro-nano cabin reaction area 28. The multi-layer micro-nano cabin 10 is distributed at 1 / 4~3 / 4 of the cylinder. Figure 2 As shown, the micro-nano chamber 10 is composed of two Y-shaped sheets 11 at an angle of 90° to 100°, with calcium fluoride seed crystals 12 placed in the middle. The Y-shaped sheet 11 is made of elastic material. When the reacting calcium fluoride grains 12 reach a certain weight, the grains 12 automatically fall out of the micro-nano chamber 10 and fall to the bottom of the micro-nano chamber reaction module II. At the same time, a vacuum exhaust device 19 is also equipped at the bottom of the micro-nano chamber reaction module II to assist the calcium fluoride grains 12 in escaping from the micro-nano chamber 10 by vacuuming.

[0030] The effluent discharge module III is a hollow structure with a gradually expanding top, divided into an inner tube 26 and an outer tube 27. The inner tube 26 and outer tube 27 are separated by an overflow weir 13. The inner tube 26 is equipped with an online pH meter 14, which is linked to the sulfuric acid dosing device 3 and sodium hydroxide dosing device 4 at the bottom of the micro-nano chamber reaction module II to control the pH of the micro-nano chamber reaction. Below the outer tube 27 are a drain outlet 29, a return outlet 30, and an online fluoride ion meter 15, which is used to monitor the fluoride ion concentration in the effluent. The drain outlet valve 16 and the return outlet valve 17 are linked to the online fluoride ion meter 15. When the fluoride ion concentration in the water of the outer cylinder 27 exceeds the discharge limit, the drain valve 16 is closed and the return valve 17 is opened, and the outlet water flows from the return pipe 25 into the raw water collection tank 18, mixes with the raw water and re-enters the device for fluoride removal treatment; when the fluoride ion concentration in the water of the outer cylinder 27 is lower than the discharge limit, the drain valve 16 is opened and the return valve 17 is closed, and the outlet water flows out from the drain pipe 31.

[0031] According to the above structure, the detailed process of the present invention is as follows:

[0032] Fluoride-containing wastewater enters the micro-nano chamber reaction module II from the raw water collection tank through an inlet pipe. Precipitants such as calcium salt, sulfuric acid, and liquid caustic soda enter the micro-nano chamber reaction module II through a dosing pipe, mixing with the fluoride-containing wastewater. The wastewater then enters the individual micro-nano chambers. Within the chambers, the fluoride ions and calcium ions in the wastewater form calcium fluoride crystals, which adhere to their surfaces and gradually grow larger. Gravity causes the openings in the thin sheet below the micro-nano chambers to expand, allowing the crystals to escape and fall into the temporary storage area at the bottom of the micro-nano chamber reaction module II. Once the crystals accumulate to a certain weight in the temporary storage area, the bottom discharge valve opens, allowing them to fall onto the upper filter screen of the crystal discharge module I, while smaller particles fall onto the lower filter screen. Air ducts on the sides of the filter screens first use a low-speed airflow to dry any residual moisture on the crystal surfaces, then use a high-speed airflow to blow the crystals down into a crystal collector. The collected calcium fluoride crystals are discharged through the discharge port for recycling. Fluoride-containing wastewater carried by the crystals is filtered into the filtrate collection tank below the filter screen. The filtrate then flows back to the raw water collection tank through the filtrate return pipe, where it mixes with the fluoride-containing raw water and continues to enter the device for fluoride removal. After the multi-layer micro-nano chamber reaction, the wastewater flows into the effluent discharge module III, passing through the overflow weir and flowing from the inner effluent cylinder into the outer effluent cylinder. Water that meets the standards flows out through the drain valve, while water that does not meet the standards flows back through the return valve and the return pipe to the raw water collection tank.

[0033] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of the present invention. The scope of the present invention is defined by the appended claims and any equivalents thereof.

Claims

1. A micro-nano cabin enhanced fluorine removal and recovery system, characterized in that: It includes a grain discharge module I, a micro-nano cabin reaction module II and a water discharge module III connected in sequence from bottom to top; The bottom of the crystal grain discharge module I is divided into a crystal grain collection area (9) and a fluorine-containing filtrate collection area (7). The crystal grain collection area (9) is used to collect the calcium fluoride crystals after drainage. The bottom is conical and is provided with a discharge port (21) connected to an external pipe, so that the crystal grains are collected and discharged from the bottom discharge port (21) into the calcium fluoride crystal collector (22); the bottom of the fluorine-containing filtrate collection area (7) is provided with a drain pipe (8), which is discharged to the fluorine-containing raw water collection pool (18) and re-enters the system for defluorination treatment; a crystal grain screen (6) is placed above the fluorine-containing filtrate collection area (7), and a row of air blowing pipes (20) are provided on the left wall of the crystal grain screen (6). By adjusting the gas flow rate, the surface moisture of the calcium fluoride crystals on the crystal grain screen (6) is blown dry, or the crystals are blown off the crystal grain screen (6) to the crystal grain collection area (9); The bottom of the micro-nano cabin reaction module II is a grain temporary storage area (32) with a conical structure. It is provided with a pressure sensor (23) and a discharge valve (5). When the calcium fluoride grains dropped from the micro-nano cabin reaction module II reach a set weight, the bottom discharge valve (5) automatically opens, the raw water inlet valve (24) closes, and the calcium fluoride grains enter the grain discharge module I. The middle part of the micro-nano cabin reaction module II is a cylindrical structure, and the lower side is provided with a raw water inlet pipe (1), a precipitant dosing device (2), a sulfuric acid dosing device (3) and a sodium hydroxide dosing device ( 4), the raw water and the reagent are fully mixed and then enter the multi-layer micro-nano chamber reaction area (28); the micro-nano chamber (10) is composed of two Y-shaped sheets (11) on the left and right, with calcium fluoride seed crystals (12) placed in the middle; the Y-shaped sheet (11) is made of elastic material, and when the reacted calcium fluoride grains reach a set weight, the grains are automatically released from the micro-nano chamber (10) and fall into the bottom of the micro-nano chamber reaction module II. At the same time, a vacuum exhaust device (19) is also provided at the bottom of the micro-nano chamber reaction module II to assist the calcium fluoride grains to be released from the micro-nano chamber (10) by vacuuming; The effluent discharge module III is a cavity structure with a gradually expanding top, and the cavity structure is divided into an inner cylinder (26) and an outer cylinder (27) by an overflow weir (13); the inner cylinder (26) is provided with an online pH meter (14), which is linked with the sulfuric acid dosing device (3) and the sodium hydroxide dosing device (4) at the bottom of the micro-nano chamber reaction module II to adjust the pH of the reaction in the micro-nano chamber (10); the outer cylinder (27) is provided with a drain port (29), a reflux port (30) and an online fluoride ion meter (15) below, and the online fluoride ion meter (15) is used to monitor the fluoride ions in the effluent. The outlet valve (16) and the return valve (17) are linked to the online fluoride meter (15); when the fluoride ion concentration in the water of the outer cylinder (27) exceeds the discharge limit, the outlet valve (16) is closed, the return valve (17) is opened, and the outlet water flows from the return pipe (25) into the fluoride-containing raw water collection tank (18), is mixed with the raw water and re-enters the device for fluoride removal treatment; when the fluoride ion concentration in the water of the outer cylinder (27) is lower than the discharge limit, the outlet valve (16) is opened, the return valve (17) is closed, and the outlet water flows out from the drain pipe (31).

2. The micro-nano chamber enhanced fluorine removal and recovery system according to claim 1, characterized in that: The crystal grain collection area (9) is located in the right 1 / 3 area of the bottom part of the crystal grain discharge module I, and the fluorine-containing filtrate collection area (7) is located in the left 2 / 3 area of the bottom part of the crystal grain discharge module I. The filtrate in the fluorine-containing filtrate collection area (7) can flow back to the fluorine-containing raw water collection pool (18).

3. The micro-nano chamber enhanced fluorine removal and recovery system according to claim 1, characterized in that: Two layers of crystal screens (6) are placed above the fluorine-containing filtrate collection area (7), with a spacing of 100-200 mm. The upper filter screen is tilted downward by 15 degrees and has a pore size of 3-5 mm. The lower filter screen is tilted downward by 30 degrees and has a pore size of 1-2 mm.

4. The micro-nano chamber enhanced fluorine removal and recovery system according to claim 1, characterized in that: The flow rate of the raw water inlet pipe (1) is controlled within a range of 30 to 50 L / min, and the flow rate of the precipitant dosing device (2) is controlled within a range of 5 to 10 L / min.

5. The micro-nano chamber enhanced fluorine removal and recovery system according to claim 1, characterized in that: The multi-layer micro-nano cabin (10) is distributed at 1 / 4 to 3 / 4 of the height of the micro-nano cabin reaction module II, and the angle between the two Y-shaped sheets (11) constituting the micro-nano cabin (10) is 90° to 100°.

6. The micro-nano chamber enhanced fluorine removal and recovery system according to claim 1, characterized in that: The diameter of the calcium fluoride seed crystal (12) in the micro-nano chamber (10) is in the range of 100 μm to 200 μm, and the volume ratio of the micro-nano chamber (10) to the calcium fluoride seed crystal (12) is in the range of 200 to 300.

7. The micro-nano chamber enhanced fluorine removal and recovery system according to claim 1, characterized in that: In the water outlet module III, a drain port (29) and a return port (30) are provided on the side wall of the outer cylinder (27), and the return port (30) is located at a height of 1 / 2 to 2 / 3 below the drain port (29).

8. The micro-nano chamber enhanced fluorine removal and recovery system according to claim 1, characterized in that: The grain discharge module I is mainly used to separate grains and wastewater and recover large-particle calcium fluoride grains formed in the micro-nano cabin reaction module II; the micro-nano cabin reaction module II mainly generates calcium fluoride on the surface of the grains through the reaction of reagents with fluoride ions in fluoride-containing wastewater in a local area; the effluent discharge module III is mainly used to discharge wastewater that meets the standards.

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