Deep defluorination system for semiconductor wastewater

Abstract

The utility model provides a deep defluorination system for semiconductor wastewater, and aims to solve the technical problems that the existing equipment cannot realize deep treatment of semiconductor wastewater and the automation degree of medicament addition is low. The system comprises a semiconductor wastewater inlet unit, a defluorination unit, a magnetic flocculation unit, a magnetic precipitation unit, a magnetic recovery unit and a dosing unit which are connected through pipelines, the dosing unit comprises a controller mounted on the control cabinet; the inlet water flow meter, the inlet water quality monitor, the outlet water quality monitor, the online pH meter, the image acquisition instrument and the medicament adding pump are in communication connection with the controller, and the controller controls the adding amount of the medicament adding pump according to the measured inlet water flow value, the measured fluorine ion content of inlet water, the measured fluorine ion content of outlet water and the measured alumen ustum image of the magnetic floc precipitate. The device has a good fluorine removal effect on low-concentration fluorine-containing wastewater, the concentration of fluorine ions in effluent is lower than 1.5 mg / L, the effect of deep fluorine removal is achieved, and unattended operation is realized.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor wastewater defluoridation technology, specifically to a deep defluoridation system for semiconductor wastewater. Background Technology

[0002] The semiconductor industry generates fluoride-containing wastewater during production. This wastewater contains complex water quality and high concentrations of pollutants, causing serious environmental impacts. In recent years, with increasing emphasis on fluoride-containing wastewater treatment by national and local governments, emission standards have become increasingly stringent. Low-fluoride wastewater, often found in semiconductor wastewater discharges, ranges in concentration from 1.5 to 10 mg / L. Discharging low-concentration fluoride wastewater into water bodies can easily cause fluoride pollution, requiring treatment. However, the presence of inorganic acids or salts often increases the difficulty of treatment. Furthermore, large-scale wastewater treatment plants handle large volumes of fluoride-containing wastewater, and reducing the fluoride ion concentration from 1.5–10 mg / L to 0.5 mg / L using reverse osmosis is often costly.

[0003] Traditional lime chemical precipitation for fluoride removal is advantageous due to its simple process, easy operation, and low operating costs. It can treat high-concentration fluoride-containing wastewater, achieving a minimum fluoride ion concentration of 8-10 mg / L. However, this method is unsuitable for treating low-concentration fluoride-containing wastewater. Coagulation sedimentation for fluoride removal involves adding a defluorinating agent, which removes fluorides from the water. This is the most mature and mature process. However, many factors influence coagulation sedimentation, such as the dosage of the coagulant, mixing intensity and time, reaction intensity and time, sedimentation time, coexisting interfering ions in the water, raw water pH, raw water temperature, turbidity, and hardness. Existing processes using this method suffer from high chemical consumption due to factors such as manual dosing. Another approach uses deep defluorination agents combined with high-density sedimentation, but because defluorination agents are mostly aluminum salts, the resulting fluoride-containing sludge is light and difficult to settle, leading to low design loads for the high-density sedimentation tanks (typically 0.6~1.0 m³). 3 / (m 2 ·h)), which makes it impossible to achieve rapid precipitation of the defluorinating agent, thus affecting the defluorination effect and efficiency.

[0004] Therefore, developing a semiconductor wastewater defluorination technology with good defluorination effect and unmanned operation is of great significance. Utility Model Content

[0005] The purpose of this invention is to solve the technical problems of unsatisfactory defluoridation effect and high reagent consumption in existing magnetic flocculation sedimentation devices. This is achieved by improving upon existing devices and adding an intelligent dosing system. A controller is installed, and connected to it are an inlet flow meter, an inlet water quality monitor, an effluent water quality monitor, an image acquisition device, and a reagent dosing pump. The controller precisely controls the reagent dosing rate based on the flow rate measured by the inlet flow meter, the fluoride ion content measured by the inlet water quality monitor, the fluoride ion content measured by the effluent water quality monitor, and the image of flocculent material in the magnetic sedimentation tank obtained by the image acquisition device. This achieves unmanned operation, saves reagent consumption, and effectively defluorinates low-concentration fluoride-containing wastewater, resulting in a fluoride ion concentration in the treated water below 1.5 mg / L.

[0006] To solve the above-mentioned technical problems, this utility model adopts the following technical solution:

[0007] A deep defluoridation system for semiconductor wastewater, characterized in that it comprises a semiconductor wastewater inlet unit, a defluoridation unit, a magnetic flocculation unit, a magnetic precipitation unit, a magnetic recovery unit, and a dosing unit connected by pipelines; the dosing unit includes:

[0008] The controller is installed on the control cabinet;

[0009] The inlet flow meter is communicatively connected to the controller and is used to monitor the inlet flow rate in real time and feed it back to the controller.

[0010] An influent water quality monitor is communicatively connected to the controller to monitor the fluoride ion content in the influent and provide feedback to the controller.

[0011] The effluent water quality monitor is connected to the controller and is used to monitor the fluoride ion content of the effluent from the magnetic sedimentation unit and feed it back to the controller.

[0012] An online pH meter, connected to the controller, is used to monitor the pH of the water before magnetic flocculation sedimentation and feed the value back to the controller. The addition of the online pH meter in this invention is because the defluoridating agent requires acidic conditions to react, and the water is acidic after the reaction. However, the downstream magnetic flocculation sedimentation requires neutral or weakly alkaline conditions to react, so it is necessary to monitor the pH value of the water and feed the value back to the controller to control the reagent dosing pump to add NaOH to the inlet pipe of the magnetic flocculation unit.

[0013] An image acquisition device, which is communicatively connected to the controller, is used to acquire images of alum flocs in the sedimentation tank of the magnetic sedimentation unit and to feed the image results back to the controller.

[0014] The agent dosing pump is connected in communication with the controller and is used to adjust the amount of agent added based on the feedback of fluoride ion content and alum flower image results.

[0015] As a preferred technical solution:

[0016] Optionally, the inlet flow meter and the inlet water quality monitor are installed on the inlet pipeline of the semiconductor wastewater inlet unit, and the inlet flow meter is installed in front of the inlet water quality monitor;

[0017] The effluent water quality monitoring instrument is installed on the effluent pipeline of the magnetic sedimentation unit;

[0018] The image acquisition device is installed above the magnetic precipitation unit;

[0019] The online pH meter is installed on the connecting pipe between the effluent of the defluorination unit and the inlet of the magnetic flocculation unit.

[0020] One end of the reagent dosing pump is connected to the reagent storage tank, and the other end is connected to the defluorination unit and the magnetic flocculation unit. It includes a defluorination agent dosing pump, a magnetic powder dosing pump and a flocculant dosing pump, which are respectively connected to the controller.

[0021] Optionally, the wastewater inlet unit includes a booster pump and an inlet pipe;

[0022] The defluorination unit includes a first baffle mixing zone and a defluorination reaction tank that are connected to each other. The defluorination reaction tank includes a primary defluorination reaction stirring tank and a secondary defluorination reaction stirring tank that are connected to each other. Both the primary defluorination reaction stirring tank and the secondary defluorination reaction stirring tank are equipped with a power stirrer.

[0023] The magnetic flocculation unit includes a second baffle mixing zone, a magnetic powder mixing reaction tank, and a flocculation reaction tank connected in sequence; both the magnetic powder mixing reaction tank and the flocculation reaction tank are equipped with a dynamic stirrer.

[0024] The magnetic sedimentation unit includes an inclined tube sedimentation tank;

[0025] The magnetic recovery unit includes a high-speed deflocculator and a magnetic recovery machine; the sludge outlet of the magnetic sedimentation unit is connected to the inlet of the high-speed deflocculator; the high-speed deflocculator transports the deflocculated magnetic sludge to the magnetic recovery machine, the magnetic recovery machine separates the magnetic powder and sludge, sends the magnetic powder to the magnetic powder storage tank, and sends the separated sludge to the sludge treatment unit; the magnetic recovery machine is connected to the feed end of the magnetic powder dosing pump.

[0026] The reagent storage tank includes a defluorinating agent storage tank, a magnetic powder storage tank, and a flocculant storage tank; each reagent storage tank is equipped with a mixing agitator.

[0027] Optionally, the feed end of the defluorinating agent dosing pump is connected to the defluorinating agent storage tank via a pipeline, and the discharge end is connected above the first baffle mixing zone and the outlet of the first-stage defluorination reaction stirring tank, respectively, to remove fluoride ions after the added defluorinating agent is fully mixed with the semiconductor wastewater.

[0028] The feed end of the magnetic powder dosing pump is connected to the magnetic powder storage tank through a pipeline, and the discharge end is connected to the mixing zone of the first baffle plate.

[0029] The feed end of the flocculant dosing pump is connected to the flocculant storage tank via a pipeline, and the discharge end is connected to the flocculation reaction tank.

[0030] Optionally, the first baffle mixing zone is located within the inlet channel of the defluorination reaction tank, and the channel is equipped with baffles for non-powered baffle mixing; the second baffle mixing zone is located within the inlet channel of the magnetic powder mixing reaction tank, and the channel is equipped with baffles for non-powered baffle mixing. The purpose of the first and second baffle mixing zones in this invention is to improve the turbulence of the water flow, making the turbulent movement within the mixing tank more intense, resulting in better mixing and facilitating the collision and adhesion of flocs and other particles for further mixing of added reagents and semiconductor fluoride-containing wastewater.

[0031] Optionally, the image acquisition device is installed above the magnetic sedimentation tank to acquire images of the magnetic floc sedimentation in the sedimentation tank and transmit the images to the controller.

[0032] Optionally, the controller is a PLC controller, used to receive the fluoride ion content and flow rate of the influent, the fluoride ion content and flow rate of the effluent, and the floc image of the magnetic sedimentation zone, and control the dosage of the defluoridant dosing pump, the magnetic powder dosing pump, and the flocculant dosing pump according to the results.

[0033] Optionally, the influent water quality monitor and the effluent water quality monitor are online fluoride ion monitors.

[0034] Optionally, it also includes a pH adjustment unit, which is disposed between the water inlet unit and the defluoridation unit;

[0035] The pH adjustment unit includes a non-powered pipeline mixer;

[0036] The reagent dosing pump also includes an oxalic acid dosing pump. The inlet of the oxalic acid dosing pump is connected to the oxalic acid storage tank via a pipeline, and the outlet is connected to the non-powered pipeline mixer. It is used to fully mix with the oxalic acid reagent when the semiconductor wastewater is alkaline to adjust the pH value of the influent to be neutral or weakly acidic. The oxalic acid dosing pump is communicatively connected to the controller.

[0037] Optionally, the non-powered pipeline mixer refers to a mixer with multiple spiral structures inside, powered by the original booster pump, used to mix oxalic acid reagent and semiconductor fluoride-containing wastewater.

[0038] Compared with the prior art, the beneficial effects of this utility model are:

[0039] 1. The semiconductor wastewater deep defluoridation system of this utility model has a high degree of automation and adopts an intelligent dosing system. That is, by setting up a controller and setting up an inlet flow meter, an inlet water quality monitor, an effluent water quality monitor, an image acquisition instrument and a reagent dosing pump that are connected to the controller for communication; the controller precisely controls the dosage of each reagent dosing pump required in the defluoridation and magnetic flocculation process according to the fluoride ion content measured by the inlet water quality monitor, the fluoride ion content measured by the effluent water quality monitor, and the image of the flocs of magnetic floc precipitation measured by the image acquisition instrument, thus realizing unmanned operation;

[0040] 2. The semiconductor wastewater deep defluoridation system of this utility model can achieve defluoridation of low-concentration fluoride-containing wastewater, and the fluoride ion concentration in the product water after defluorination is less than 1.5 mg / L.

[0041] 3. The semiconductor wastewater deep defluoridation system of this utility model adopts magnetic flocculation sedimentation rapid deep defluoridation technology, which makes the defluoridation of low-concentration fluoride-containing wastewater more low-carbon, efficient, and environmentally friendly, and has low cost. It also has a certain degree of flexibility and adaptability, effectively solving the technical problems of traditional defluoridation technologies such as low dosing accuracy, high energy consumption, large carbon emissions, high operating costs, large footprint, and difficulty in rapid sedimentation after the addition of defluoridating agents. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] Figure 1 This is a system flowchart of this utility model;

[0044] Figure 2 This is a schematic diagram of the structure of the device used in the system of this utility model;

[0045] Figure 3 This is a structural diagram of the PLC controller feedback control system of this utility model;

[0046] Figure label:

[0047] 101-Inlet flow meter; 102-Inlet water quality monitor; 201-First baffle mixing zone; 202-Defluoridation reaction tank; 203-First-stage defluoridation reaction stirring tank; 204-Second-stage defluoridation reaction stirring tank; 205-Online pH meter; 301-Second baffle mixing zone; 302-Magnetic powder mixing reaction tank; 303-Dual-blade mechanical agitator; 304-Guide cylinder; 305-Flocculation reaction tank; 306-Multi-stage heterogeneous impeller; 307-Connecting pipe; 401-High-efficiency magnetic sedimentation zone; 402-Sedimentation tank inlet zone; 403-Sludge scraper; 404-Inclined... Pipe sedimentation zone; 405- Inclined pipe support beam; 406- Pressure sensor; 407- Effluent weir; 408- Effluent outlet; 409- Magnetic mud reflux pump; 410- Effluent flow meter; 411- Effluent water quality monitor; 412- High-definition camera; 501- High-speed deflocculator; 502- Magnetic recovery machine; 601- Oxalic acid dosing device; 602- Defluoridant dosing device; 603- NaOH dosing device; 604- Flocculant dosing device; 605- Magnetic powder dosing device; 701- Control cabinet; 702- PLC controller; 801- Non-powered pipeline mixer. Detailed Implementation

[0048] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0049] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this utility model is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this utility model and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0051] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0052] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0053] The following disclosure provides many different embodiments or examples for implementing various structures of this invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the scope of the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0054] The embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0055] This utility model embodiment provides a deep defluoridation system for semiconductor wastewater, such as... Figure 1 As shown, it includes a semiconductor wastewater inlet unit, a defluoridation unit, a magnetic flocculation unit, a magnetic sedimentation unit, a magnetic recovery unit, and a dosing unit connected by pipelines;

[0056] The wastewater inlet unit includes a booster pump and an inlet pipe;

[0057] The defluorination unit includes a first baffle mixing zone and a defluorination reaction tank; the first baffle mixing zone is located in the inlet channel of the defluorination reaction tank, and the channel is equipped with baffles for non-powered baffle mixing;

[0058] The magnetic flocculation unit includes a second baffle mixing zone, a magnetic powder mixing reaction tank, and a flocculation reaction tank connected in sequence; the second baffle mixing zone is set in the inlet channel of the magnetic powder mixing reaction tank, and the channel is equipped with baffles for non-powered baffle mixing;

[0059] The magnetic sedimentation unit includes an inclined tube sedimentation tank;

[0060] The magnetic recovery unit includes a high-speed deflocculator and a magnetic recovery machine; the sludge outlet of the magnetic sedimentation unit is connected to the inlet of the high-speed deflocculator; the high-speed deflocculator transports the deflocculated magnetic sludge to the magnetic recovery machine, the magnetic recovery machine separates the magnetic powder and sludge, sends the magnetic powder to the magnetic powder storage tank, and sends the separated sludge to the sludge treatment unit; the reagent storage tanks include a defluorinating agent storage tank, a magnetic powder storage tank, and a flocculant storage tank; each reagent storage tank is equipped with a mixing agitator.

[0061] The dosing unit includes:

[0062] The controller is installed on the control cabinet;

[0063] The inlet flow meter is connected to the controller to monitor the inlet flow rate in real time and feed it back to the controller.

[0064] The influent water quality monitor is connected to the controller to monitor the fluoride ion content in the influent and provide feedback to the controller. The influent flow meter and the influent water quality monitor are installed on the influent pipe of the semiconductor wastewater influent unit, with the influent flow meter located in front of the influent water quality monitor. The influent water quality monitor is an online fluoride ion monitor.

[0065] The effluent water quality monitor is connected to the controller and is used to monitor the fluoride ion content in the effluent from the magnetic sedimentation unit and feed it back to the controller. The effluent water quality monitor is installed on the effluent pipeline of the magnetic sedimentation unit and is an online fluoride ion monitor.

[0066] An online pH meter, which communicates with the controller, is used to monitor the pH of the water before magnetic flocculation sedimentation and feeds the value back to the controller.

[0067] The image acquisition device, which communicates with the controller, is used to acquire images of the flocs in the magnetic precipitation unit and feed the image results back to the controller. The image acquisition device is installed above the magnetic precipitation unit, specifically above the inclined tube reaction tank, to acquire images of the magnetic floc sedimentation in the sedimentation tank and transmit the images to the controller.

[0068] An online pH meter is installed on the connecting pipe between the effluent from the defluoridation unit and the inlet of the magnetic flocculation unit.

[0069] A reagent dosing pump, communicating with the controller, is used to adjust the dosage of the reagent based on the feedback of fluoride ion content and alum floc image results. One end of the reagent dosing pump is connected to the reagent storage tank, and the other end is connected to the defluorination unit and the magnetic flocculation unit. It includes a defluorinating agent dosing pump, a magnetic powder dosing pump, and a flocculant dosing pump, each communicating with the controller.

[0070] The specific settings for the dosing pump to achieve material dosing are as follows:

[0071] The feed end of the defluorinating agent dosing pump is connected to the defluorinating agent storage tank through a pipeline, and the discharge end is connected to the mixing zone of the first baffle plate. This pump is used to fully mix the added defluorinating agent with the semiconductor wastewater before it enters the defluorination reaction tank to remove fluoride ions.

[0072] The feed end of the magnetic powder dosing pump is connected to the magnetic powder storage tank through a pipeline, and the discharge end is connected to the mixing zone of the first baffle plate.

[0073] The feed end of the flocculant dosing pump is connected to the flocculant storage tank via a pipeline, and the discharge end is connected to the flocculation reaction tank.

[0074] The magnetic recovery machine is connected to the feed end of the magnetic powder dosing pump;

[0075] It also includes a pH adjustment unit, located between the influent unit and the defluorination unit, comprising a non-powered pipeline mixer. The reagent dosing pump also includes an oxalic acid dosing pump, whose inlet is connected to an oxalic acid storage tank via pipeline, and whose outlet is connected to the non-powered pipeline mixer. This pump is used to thoroughly mix the oxalic acid reagent with the semiconductor wastewater when it is alkaline, thereby adjusting the pH of the influent to neutral or weakly acidic. The oxalic acid dosing pump is communicatively connected to the controller. The reagent dosing pump also includes a NaOH dosing pump, whose inlet is connected to a NaOH storage tank via pipeline, and whose outlet is connected to the second baffle mixing zone, used for acid-base neutralization. The non-powered pipeline mixer has multiple internal spiral structures and is powered by the original booster pump, used to mix the oxalic acid reagent and the semiconductor fluoride-containing wastewater.

[0076] In this embodiment, the controller is a PLC controller, which is used to receive the fluoride ion content value, influent flow rate, influent pH value, effluent ion content value and effluent flow rate, as well as the floc image of the magnetic sedimentation zone, and control the dosage of the defluoridant dosing pump, magnetic powder dosing pump and flocculant dosing pump according to the results.

[0077] A schematic diagram of the device used in the semiconductor wastewater deep defluorination system of this invention is shown below. Figure 2 As shown, the details are as follows:

[0078] (1) Semiconductor wastewater inlet unit

[0079] Semiconductor wastewater is pumped to the ground by a booster pump and enters the inlet pipe. An inlet flow meter 101 is installed on the inlet pipe (the signal line is connected to the control cabinet 701 to transmit feedback monitoring signals). An inlet water quality monitor 102 is installed behind the inlet flow meter 101 (the signal line is connected to the control cabinet 701 to transmit feedback monitoring signals).

[0080] (2) Defluorination unit

[0081] It includes a first baffle mixing zone 201 (with baffles in the flow channel, non-powered baffle mixing, which improves the turbulence of the water flow, makes the turbulent movement in the reactor more intense, has a better mixing effect, and is conducive to the collision and adhesion of particles to further mix the defluorinating agent and semiconductor fluoride wastewater), a defluorination reaction tank 202 (two-stage stirring, namely the first-stage defluorination reaction stirring tank 203 and the second-stage defluorination reaction stirring tank 204, both of which are differential speed stirrers), and an online pH meter 205.

[0082] (3) Magnetic flocculation unit

[0083] Traditional coagulation mixing tanks consist of three stages: two-stage coagulation and one-stage flocculation, all using parallel paddle agitation with a mixing time of 6.0–10.0 min. This device, designed for space-constrained environments and requiring minimal floor space, innovatively employs a high-efficiency coagulation mixing tank in two stages: one-stage coagulation (enhanced by a flow guide tube) and one-stage flocculation (differential agitation), with a coagulation time of 4.5–6.0 min and a smaller footprint. Compared to three-stage coagulation, the coagulation system reduces hydraulic retention time by over 25%, saves over 10% in floor space, reduces energy consumption by over 15%, and lowers equipment costs by over 5%.

[0084] The reactor comprises a second baffle mixing zone 301 (with baffles in the flow channel for non-powered baffle mixing, improving water flow turbulence, resulting in more intense turbulent flow within the reactor, better mixing effect, and facilitating the collision and agglomeration of floc particles for further mixing of magnetic powder reagents and fluoride-containing wastewater; designed residence time 20-40 s), and a magnetic powder mixing reaction tank 302 (containing magnetic powder and magnetic mud recovered from the magnetic mud return pump 411, with a double-blade mechanical stirrer 303 and an internal guide tube 304. Under the mechanical stirring action, radial and axial flows can be formed within the guide tube, improving water flow turbulence, resulting in more intense turbulent flow within the reactor, maximizing the utilization of stirring energy, and improving coagulation effect; designed residence time 90-120 s). s), flocculation reaction tank 305 (with multiple levels of heterogeneous blades 306 inside, the lower blades are large and the upper blades are small. Through the differential stirring of the multi-level blades of different sizes, flocculation is carried out step by step. The stirring intensity at the lower end is high, and the number of collisions of floc particles is high. At the same time, the bottom solid particles are washed away to prevent the bottom magnetic powder from settling and caking due to gravity. The stirring intensity at the upper end is low to prevent the floc from breaking due to the same stirring intensity as the lower end, ensuring the stability of the flocculated effluent. The designed residence time is 180~240 s), connecting pipe 307 (connecting the magnetic flocculation unit and the magnetic sedimentation unit, gravity flow).

[0085] (4) Magnetic precipitation unit

[0086] We have innovatively developed a radial flow square sedimentation tank with "single-sided water inlet and peripheral water outlet" to improve sedimentation and sludge removal efficiency, increase the utilization rate of equipment tank space, and reduce equipment investment costs. Compared with high-density sedimentation tanks, sedimentation efficiency is increased by 19% and the space utilization rate is increased by 22%. At the same time, we have developed inclined tube vibration self-cleaning technology to solve the problem of manual cleaning, realize automated monitoring and cleaning, improve system operation stability, and reduce operation and maintenance difficulty and workload.

[0087] Inclined tube sedimentation is adopted, including a high-efficiency magnetic sedimentation zone 401 and a sedimentation tank inlet zone 402 (including a water flow baffle). The sedimentation tank inlet adopts a submerged design, that is, the liquid level at the inlet is higher than that at the outlet, to avoid the water head falling and causing floc breakage, which would affect the sedimentation effect. The flow velocity below the water flow baffle of the sedimentation tank is controlled at 0.02~0.03 m / s. If the flow velocity is too low, flocs are prone to escape near the inlet end; if the flow velocity is too high, flocs are prone to escape far from the inlet end.

[0088] Sludge scraper 403 (removes sludge settled at the bottom of the tank; the bottom scraper scrapes the sludge to the central sludge hopper), inclined tube sedimentation zone 404, inclined tube support beam 405 (channel steel or I-beam), pressure sensor 406 (traditional cleaning methods involve automatic flushing via pre-buried pipes or manual flushing by emptying the tank, both requiring system shutdown and resulting in low efficiency; this device installs a pressure sensor in the inclined tube sedimentation zone, and the pressure sensor 406 communicates with the control cabinet 701 via a signal line to achieve automated monitoring and cleaning, improve system stability, and reduce maintenance difficulty and workload), effluent weir 407, and outlet 40 8. Magnetic mud reflux pump 409 (adopts a positive displacement pump with good anti-clogging performance; even if the pipeline is blocked during operation, it can be cleared by reversing), effluent flow meter 410 (signal line connected to control cabinet 701 to transmit feedback monitoring signal), effluent water quality monitor 411 (signal line connected to control cabinet 701 to transmit feedback monitoring signal), high-definition camera 412 (i.e., image acquisition device, installed at the upper end of the high-efficiency magnetic sedimentation zone 401; it uses particle imaging method to intuitively evaluate the quality of floc sedimentation, i.e., the magnetic floc sedimentation situation is captured in real time by the high-definition camera).

[0089] (5) Magnetic recycling unit

[0090] High-speed deflocculator 501 (with a high-speed dispersing wheel at the center, which uses the rapid rotation of the high-speed dispersing wheel to shear the sludge flocs containing magnetic powder, thereby separating the magnetic powder and sludge; through the high-speed rotating cutter disc and the unique water flow channel design, the magnetic media floc sludge is dispersed into magnetic media and non-magnetic sludge); magnetic recovery machine 502 (used to recover the magnetic powder from the high-speed deflocculator 501 and add the recovered magnetic powder to the magnetic powder mixing reaction tank 302).

[0091] (6) Dosing unit and intelligent control

[0092] The system includes an oxalic acid dosing device 601 (the dosing port is located on the pH adjustment unit, i.e., the non-powered pipeline mixer 801; if the influent semiconductor wastewater is the effluent from a biochemical process or other neutral water, no dosing is required; if the influent semiconductor wastewater is from a lime precipitation defluorination process, i.e., the wastewater is alkaline, then it is thoroughly mixed with oxalic acid to adjust the pH of the influent to neutral or weakly acidic), a defluorinating agent dosing device 602 (with two dosing ports, located above the first baffle mixing zone 201 and at the outlet of the first-stage defluorination reaction mixing tank 203), a NaOH dosing device 603 (located at the connection between the outlet of the second-stage defluorination reaction mixing tank 204 and the influent of the second baffle mixing zone 301), a flocculant dosing device 604 (the dosing port is located below the flocculation reaction tank 305), and a magnetic powder dosing device 605 (the dosing port is located below the magnetic powder mixing reaction tank 302). All four dosing units include a variable frequency dosing pump, a reagent storage tank, and a mixer.

[0093] The control cabinet 701 and PLC controller 702 (receive real-time monitoring feedback of inlet and outlet water flow rates and fluoride ion content, then calculate the dosage according to the algorithm, and feed it back to each chemical dosing pump, and adjust the dosage by frequency conversion to achieve intelligent and precise dosing) are connected to online water quality monitoring instruments, high-definition cameras, magnetic flocculation units, magnetic sedimentation units, magnetic recovery units, and chemical dosing units; a one-button start / stop function is set up to realize one-button start and stop.

[0094] The PLC controller can intelligently control fluoride dosing based on feedback from influent and effluent water quality (i.e., the dosage can be set according to the fluoride ion content; for example, the defluoridation effect is best when the dosage of defluoridant is 100-200 times the fluoride ion content of the influent). The structure of the PLC controller feedback control system is as follows: Figure 3 As shown.

[0095] The semiconductor wastewater deep defluoridation system of this invention is used for defluoridation of semiconductor wastewater. The main equipment occupies an area of ​​approximately 79 m². 2 / (ten thousand m) 3 ·d -1 The total hydraulic retention time (HRT) is approximately 15 minutes, and the design load is 15~40 m³. 3 / (m 2 The settling velocity is 15-40 m / h; while existing technologies often use high-density sedimentation to deeply defluorinate semiconductor wastewater, with the main equipment occupying an area of ​​approximately 100 m². 2 / (ten thousand m) 3 ·d -1 The total hydraulic retention time (HRT) is approximately 20 minutes, and the design load is 1.0~15 m. 3 / (m 2 The settling velocity is 1.0~15 m / h. Therefore, by adopting the magnetic coagulation sedimentation system of this utility model, the equipment saves more than 20% of the floor space, shortens the total hydraulic retention time (HRT) by more than 25%, increases the settling velocity by more than 2 times, and greatly improves the deep defluorination efficiency, thus achieving rapid defluorination.

[0096] Verification has shown that the advanced defluoridation system of this invention was successfully used in a semiconductor wastewater treatment project. The influent to the system consisted of water that had undergone preliminary defluorination via lime precipitation, and the treatment capacity was 500 m³ / s. 3 The raw water has a fluoride concentration of 8-10 mg / L and a pH > 10. After advanced treatment, the fluoride concentration in the treated water is less than 1.5 mg / L and the pH is 7-9, meeting the requirements for discharge into surface water, i.e., meeting the requirements of the "Surface Water Environmental Quality Standard" (GB 3838-2002, the fluoride concentration discharge limit for Class IV and V surface water bodies is 1.5 mg / L), demonstrating excellent fluoride removal effect.

Claims

1. A deep defluoridation system for semiconductor wastewater, characterized in that: The system includes a semiconductor wastewater inlet unit, a defluoridation unit, a magnetic flocculation unit, a magnetic sedimentation unit, a magnetic recovery unit, and a dosing unit, all connected by pipelines. The dosing unit includes: The controller is installed on the control cabinet; The inlet flow meter is communicatively connected to the controller and is used to monitor the inlet flow rate in real time and feed it back to the controller. The influent water quality monitor is connected to the controller and is used to monitor the fluoride ion content and pH value in the influent water and provide feedback to the controller. The effluent water quality monitor is connected to the controller and is used to monitor the fluoride ion content of the effluent from the magnetic sedimentation unit and feed it back to the controller. An online pH meter, which is connected to the controller, is used to monitor the pH of the water before magnetic flocculation sedimentation and feeds the value back to the controller. An image acquisition device, which is connected to the controller, is used to acquire images of alum flocs during magnetic floc sedimentation and to feed the image results back to the controller. The agent dosing pump is connected in communication with the controller and is used to adjust the amount of agent added based on the feedback of fluoride ion content and alum flower image results.

2. The semiconductor wastewater deep defluorination system according to claim 1, characterized in that, The inlet flow meter and the inlet water quality monitor are installed on the inlet pipeline of the semiconductor wastewater inlet unit, and the inlet flow meter is installed in front of the inlet water quality monitor. The effluent water quality monitoring instrument is installed on the effluent pipeline of the magnetic sedimentation unit; The image acquisition device is installed above the magnetic precipitation unit; The online pH meter is installed on the connecting pipe between the effluent of the defluorination unit and the inlet of the magnetic flocculation unit. One end of the reagent dosing pump is connected to the reagent storage tank, and the other end is connected to the defluorination unit and the magnetic flocculation unit. It includes a defluorination agent dosing pump, a magnetic powder dosing pump and a flocculant dosing pump, which are respectively connected to the controller.

3. The semiconductor wastewater deep defluorination system according to claim 2, characterized in that: The wastewater inlet unit includes a booster pump and an inlet pipe; The defluorination unit includes a first baffle mixing zone and a defluorination reaction tank that are connected to each other. The defluorination reaction tank includes a primary defluorination reaction stirring tank and a secondary defluorination reaction stirring tank that are connected to each other. Both the primary defluorination reaction stirring tank and the secondary defluorination reaction stirring tank are equipped with a power stirrer. The magnetic flocculation unit includes a second baffle mixing zone, a magnetic powder mixing reaction tank, and a flocculation reaction tank connected in sequence; both the magnetic powder mixing reaction tank and the flocculation reaction tank are equipped with a dynamic stirrer. The magnetic sedimentation unit includes an inclined tube sedimentation tank; The magnetic recovery unit includes a high-speed deflocculator and a magnetic recovery machine; the sludge outlet of the inclined tube sedimentation tank is connected to the inlet of the high-speed deflocculator; the high-speed deflocculator transports the deflocculated magnetic sludge to the magnetic recovery machine, the magnetic recovery machine separates the magnetic powder and sludge, sends the magnetic powder to the magnetic powder storage tank, and sends the separated sludge to the sludge treatment unit; the magnetic recovery machine is connected to the feed end of the magnetic powder dosing pump. The reagent storage tank includes a defluorinating agent storage tank, a magnetic powder storage tank, and a flocculant storage tank; each reagent storage tank is equipped with a mixing agitator.

4. The semiconductor wastewater deep defluorination system according to claim 3, characterized in that: The feed end of the defluorinating agent dosing pump is connected to the defluorinating agent storage tank through a pipeline, and the discharge end is connected above the first baffle mixing zone and the outlet of the first-stage defluorination reaction stirring tank, respectively, to remove fluoride ions after the added defluorinating agent is fully mixed with the semiconductor wastewater. The feed end of the magnetic powder dosing pump is connected to the magnetic powder storage tank through a pipeline, and the discharge end is connected to the mixing zone of the first baffle plate. The feed end of the flocculant dosing pump is connected to the flocculant storage tank via a pipeline, and the discharge end is connected to the flocculation reaction tank.

5. The semiconductor wastewater deep defluorination system according to claim 4, characterized in that: The first baffle mixing zone is located in the inlet channel of the defluorination reaction tank, and the channel is equipped with baffles for non-powered baffle mixing; the second baffle mixing zone is located in the inlet channel of the magnetic powder mixing reaction tank, and the channel is equipped with baffles for non-powered baffle mixing.

6. The semiconductor wastewater deep defluorination system according to claim 2, characterized in that: The controller is a PLC controller, used to receive the fluoride ion content and flow rate of the influent, the fluoride ion content and flow rate of the effluent, and the floc image of the magnetic sedimentation zone, and control the dosage of the defluoridating agent dosing pump, the magnetic powder dosing pump, and the flocculant dosing pump according to the results.

7. The semiconductor wastewater deep defluorination system according to claim 1, characterized in that: The influent water quality monitoring instrument and the effluent water quality monitoring instrument are both online fluoride ion monitoring instruments.

8. The semiconductor wastewater deep defluoridation system according to claim 1, characterized in that: It also includes a pH adjustment unit, which is disposed between the water inlet unit and the defluoridation unit; The pH adjustment unit includes a non-powered pipeline mixer; The reagent dosing pump also includes an oxalic acid dosing pump. The inlet of the oxalic acid dosing pump is connected to the oxalic acid storage tank via a pipeline, and the outlet is connected to the non-powered pipeline mixer. It is used to fully mix with the oxalic acid reagent when the semiconductor wastewater is alkaline to adjust the pH value of the influent to be neutral or weakly acidic. The oxalic acid dosing pump is communicatively connected to the controller.

9. A semiconductor wastewater deep defluoridation system according to claim 8, characterized in that: The non-powered pipeline mixer refers to a mixer with multiple spiral structures inside, powered by the original booster pump, used to mix oxalic acid reagents and semiconductor fluoride-containing wastewater.

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