Fluorine-containing wastewater pretreatment device

Abstract

The utility model discloses a fluorine-containing wastewater pretreatment device which comprises a series system consisting of a wastewater regulating tank, a multi-stage reaction unit, an inclined tube sedimentation tank, a treatment tank, a TMF (Tetramethylbenzidine) circulating unit and an activated carbon filter tank. The innovation points are as follows: the multi-stage reaction unit adopts the volume gradient design of a first-stage reaction tank and a second-stage reaction tank in a ratio of 1: 1.2-1.5, and is provided with a continuous turn-back type deflection baffle, so that the hydraulic retention time is prolonged by 40-60%, and the chelation reaction of fluorine ions and ferric salt / aluminum salt is enhanced. 50-60-degree hexagonal honeycomb filler is adopted in the inclined tube sedimentation tank to improve the floccule interception efficiency, a gel growth tank with an online particle size detection function is additionally arranged between the treatment tank and the TMF unit, and PAC is accurately added through 80-150-micrometer floccule particle size threshold value control. The matched sludge treatment system converts the fluorine-containing sludge into activated carbon through oxygen-controlled carbonization at 400-600 DEG C, so that the hazardous waste is reduced, and the adsorption capacity of the filter tank is improved. According to the device, through the multi-stage synergistic effect, the fluorine removal rate is increased, and meanwhile, the problem of blockage of the TMF membrane assembly is effectively avoided.

Description

A fluoride-containing wastewater pretreatment device Technical Field

[0001] This utility model relates to the technical field of wastewater treatment devices, specifically to a pretreatment device for fluoride-containing wastewater. Background Technology

[0002] Fluorine-based wastewater is one of the main wastewater discharges in the semiconductor industry. Its sources include wastewater generated from the use of hydrofluoric acid during wafer cleaning and wet etching, wastewater generated from resin regeneration in the water recovery system, exhaust gas treatment facilities, exhaust gas scrubbing towers, etc.

[0003] Utility model patent CN219709319U discloses a fluoride-containing wastewater treatment system. It utilizes NaOH and calcium chloride as defluorinating agents in a reaction tank to effectively precipitate fluoride ions in the wastewater, removing them there. Then, in a subsequent circulation tank, PAC (polyacrylamide) is used for flocculation and adsorption precipitation to remove other pollutants, achieving good purification. A TMF (diluted silicate) device is added after the circulation tank to concentrate the wastewater and prevent back dissolution. However, direct-connection flocculation and sedimentation suffers from gel leakage and clogging of the subsequent TMF device. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a fluoride-containing wastewater pretreatment device that achieves efficient oxidation treatment of organic wastewater through the synergistic effect of multi-stage reaction units.

[0005] To achieve the above objectives, the technical solution provided by this utility model is as follows:

[0006] A fluoride-containing wastewater pretreatment device includes a wastewater equalization tank, a multi-stage reaction unit, an inclined tube sedimentation tank, a treatment tank, a TMF circulation unit, and an activated carbon filter tank connected in sequence; the multi-stage reaction unit consists of a primary reaction tank and a secondary reaction tank connected in series, and at least one of the reaction tanks is equipped with a baffle; a gel growth tank is provided between the treatment tank and the TMF circulation unit.

[0007] Furthermore, the volume ratio of the primary reaction tank to the secondary reaction tank is 1:1.2-1.5, and the baffles installed in each reaction tank are continuous reversible flow guiding structures.

[0008] Furthermore, the primary reaction tank and / or the secondary reaction tank are equipped with a pretreatment agent dosing device, wherein the pretreatment agent includes at least one of iron salt, aluminum salt, and lime.

[0009] Furthermore, the bottom of the inclined tube sedimentation tank is equipped with a sludge collection hopper, and the top is installed with hexagonal honeycomb inclined tube packing, the inclination angle of which is 50-60 degrees.

[0010] Furthermore, an online particle size analyzer is installed in the gel growth tank. The online particle size analyzer is electrically connected to the PAC dosing system through a controller, and the floc particle size control threshold is 80-150 μm.

[0011] Furthermore, the device is equipped with a sludge treatment system, including a sludge tank and a sludge filter press connected in sequence, wherein the input end of the sludge tank is connected to the output end of an inclined tube sedimentation tank and / or a TMF circulation unit.

[0012] Furthermore, the sludge treatment system is also connected to a sludge carbonization module, which consists of a screw conveyor and a temperature-controlled pyrolysis furnace, with the pyrolysis temperature controlled at 400-600℃.

[0013] Furthermore, an RO (semi-permeable membrane) system is installed downstream of the activated carbon filter tank. The RO membrane system includes a high-pressure pump set and a membrane stack array. The product water end is connected to the product water tank, and the product water end returns to the TMF circulation unit.

[0014] Furthermore, both the RO membrane system and the TMF circulation unit are equipped with a membrane cleaning system, which includes an acid washing tank, an alkaline washing tank, and an ultrasonic oscillation generator.

[0015] Furthermore, the pyrolysis furnace of the sludge carbonization module is equipped with a nitrogen protection device.

[0016] As an explanation, the various units, devices, and pools can be connected by pipes and / or valves, as well as by setting a height difference. The valves are preferably electronic valves, that is, valve mechanisms equipped with electric actuators. The electric actuators can be electrically connected to the aforementioned controller for automated control of valve opening and closing.

[0017] The advantages and beneficial effects of this invention are as follows: By using a volume gradient of 1:1.2-1.5 between the primary and secondary reaction tanks, combined with a baffle structure, the hydraulic retention time is extended by 40%-60%, allowing for a more complete chelation reaction between fluoride ions and reagents such as iron / aluminum salts, thereby improving the fluoride removal rate. Through a controlled-oxygen carbonization process at 400-600℃ in a pyrolysis furnace, fluoride-containing sludge is converted into regenerated activated carbon, achieving hazardous waste reduction while simultaneously improving the adsorption capacity of the filter tank. Attached Figure Description

[0018] Figure 1 is a structural schematic diagram of this utility model;

[0019] Figure 2 is a schematic diagram of the structure of the reaction tank of this utility model;

[0020] Figure 3 is a cross-sectional view of the sedimentation tank of this utility model;

[0021] In the diagram: 1- Primary / Secondary reaction tank, 2- Baffle plate, 3- Inclined tube sedimentation tank, 4- Packing layer. Detailed Implementation

[0022] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solution of this utility model and should not be construed as limiting the scope of protection of this utility model.

[0023] Example 1

[0024] This embodiment provides a pretreatment device for fluoride-containing wastewater, comprising a wastewater equalization tank, a multi-stage reaction unit, an inclined tube sedimentation tank, a treatment tank, a gel growth tank, a TMF circulation unit, and an activated carbon filter tank connected in series via pipelines equipped with electric valves. The multi-stage reaction unit includes a primary / secondary reaction tank 1 with a volume ratio of 1:1.2-1.5. A continuous, reversible baffle 2 forms a serpentine flow channel within the tank, which, in conjunction with an iron / aluminum salt metering pump dosing system, extends the fluoride ion chelation reaction time by 40%-60%. The inclined tube sedimentation tank 3 uses a 55±5° hexagonal honeycomb inclined tube packing layer 4, with a conical sludge hopper at the bottom connected to the sludge treatment system via a pneumatic valve. The gel growth tank incorporates a laser particle size analyzer and a PAC dosing pump for interlocked control, maintaining the floc particle size within the 80-150μm threshold range. The TMF circulation unit shares an acid / alkali washing tank and an ultrasonic membrane cleaning system with the RO membrane system. RO concentrate is returned to the gel growth tank after pH adjustment. The sludge carbonization module employs two-stage pyrolysis (400℃ / 600℃) with nitrogen protection, and the carbonization products are recycled to the activated carbon filter. This device achieves a fluoride removal rate of ≥92%, maintains a TMF membrane flux of over 50 LMH, and achieves a sludge reduction rate of 75%.

[0025] Example 2

[0026] This embodiment provides another implementation method, differing from Embodiment 1 in that the multi-stage reaction unit adopts a 1:1.5 volume ratio design, and the secondary reaction tank is equipped with double-layer baffles to form a three-dimensional flow pattern. The inclined tube sedimentation tank uses a 60-degree inclined packing layer, and the bottom sludge hopper is connected to the sludge carbonization module through a pneumatic sludge discharge valve. The gel growth tank is equipped with a floc monitoring system to control the PAC dosage and stabilize the flocs at 120μm. The TMF circulation unit is equipped with a cross-flow tubular membrane module and shares a cleaning system containing citric acid and sodium hypochlorite with the RO system. Sludge treatment adopts a two-stage carbonization process: the primary pyrolysis furnace operates at 400℃ in a nitrogen environment, and the secondary pyrolysis temperature is increased to 600℃. The effluent from the activated carbon filter is pumped to the spiral wound RO membrane stack via a high-pressure pump set, and the permeate conductivity is controlled below 50μS / cm. The concentrate is returned to the gel growth tank for further treatment after pH adjustment.

[0027] The working principle of this invention is as follows: Wastewater first enters a series of primary and secondary reaction tanks. Continuous baffles within these tanks force the water flow into a serpentine path, extending the hydraulic retention time. By adding agents such as iron / aluminum salts, fluoride ions chelate with the metal ions in the agents, forming stable fluoride precipitates. The reacted wastewater then enters an inclined tube sedimentation tank, where shallow sedimentation accelerates floc settling. A conical sludge hopper at the bottom collects fluoride-containing sludge, while the clear water at the top enters the treatment tank. The effluent from the treatment tank enters a gel growth tank, where an online particle size analyzer monitors the floc size in real time, controlling the PAC dosage based on feedback. When the detected particle size is below the lower limit, the PAC dosage is automatically increased to promote floc aggregation; when it exceeds the limit, the dosage is reduced to prevent floc breakage. TMF (Transfer Fluoride Mist) concentrates the wastewater through cross-flow filtration, with the concentrated water returned to the front end for further treatment. The permeate is then adsorbed by activated carbon before entering the RO (Reverse Oxidation) system. The sludge treatment system performs temperature-controlled pyrolysis of the sludge generated in the sedimentation tank and TMF, achieving sludge reduction and resource recycling.

[0028] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A pretreatment device for fluoride-containing wastewater, characterized in that: It includes a wastewater equalization tank, a multi-stage reaction unit, an inclined tube sedimentation tank, a treatment tank, a TMF circulation unit, and an activated carbon filter tank connected in sequence; the multi-stage reaction unit consists of a primary reaction tank and a secondary reaction tank connected in series, and at least one of the reaction tanks is equipped with a baffle; a gel growth tank is provided between the treatment tank and the TMF circulation unit.

2. The apparatus according to claim 1, characterized in that: The volume ratio of the primary reaction tank to the secondary reaction tank is 1:1.2-1.5, and the baffles installed in each reaction tank are continuous reversible flow guiding structures.

3. The apparatus of claim 1, wherein: The primary reaction tank and / or the secondary reaction tank are equipped with a pretreatment agent dosing device, and the pretreatment agent includes at least one of iron salt, aluminum salt, and lime.

4. The apparatus according to claim 1, characterized in that: The inclined tube sedimentation tank is equipped with a sludge collection hopper at the bottom and a hexagonal honeycomb inclined tube packing at the top, with the packing inclined at an angle of 50-60 degrees.

5. The apparatus of claim 1, wherein: An online particle size analyzer is installed in the gel growth tank. The online particle size analyzer is electrically connected to the PAC dosing system through a controller. The floc particle size control threshold is 80-150 μm.

6. The apparatus of claim 1, wherein: The device is equipped with a sludge treatment system, including a sludge tank and a sludge filter press connected in sequence. The input end of the sludge tank is connected to the output end of an inclined tube sedimentation tank and / or a TMF circulation unit.

7. The apparatus of claim 6, wherein: The sludge treatment system is also connected to a sludge carbonization module, which includes a screw conveyor and a temperature-controlled pyrolysis furnace.

8. The apparatus of claim 7, wherein: A reverse osmosis (RO) membrane system is installed downstream of the activated carbon filter. The RO membrane system includes a high-pressure pump set and a membrane stack array. The product water end is connected to the product water tank, and the product water end returns to the TMF circulation unit.

9. The apparatus of claim 8, wherein: Both the RO membrane system and the TMF circulation unit are equipped with a membrane cleaning system, which includes an acid washing tank, an alkaline washing tank, and an ultrasonic oscillation generator.

10. The apparatus of claim 7, wherein: The pyrolysis furnace of the sludge carbonization module is equipped with a nitrogen protection device.

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