Semiconductor industry fluorine-containing wastewater treatment system and method

Abstract

The invention discloses a semiconductor industry fluorine-containing wastewater treatment system and method. The treatment system comprises an adjusting unit, a pretreatment unit, a phosphorus recovery unit, a biochemical treatment and membrane separation unit and a phosphorus release and calcium removal unit. The phosphorus release and calcium removal unit is used for releasing phosphorus in the membrane separation concentrated water and enabling the phosphorus and partial hydrolytic acidification water of the biochemical treatment and membrane separation unit to enter the phosphorus recovery unit after being subjected to rotational flow enrichment; the phosphorus recovery unit is used for inducing calcium ions and phosphate radical ions in the wastewater to quickly form calcium fluoride and calcium phosphate by taking unprecipitated calcium fluoride, newly generated calcium fluoride and calcium phosphate and calcium fluoride refluxed by the phosphorus release and calcium removal unit as crystal nucleuses by utilizing the high pH value of the pretreatment unit; and finally, the calcium ions are removed from the system in a physicochemical sludge discharge and phosphorus product recovery mode, so that the influence of the calcium ions on the MBR membrane is reduced, the phosphorus recovery rate is improved, the use amount of the precipitant and the sludge amount are reduced, the medicament consumption is reduced, and the stable operation of the biochemical system is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a system and method for treating fluorine-containing wastewater in semiconductor industry. Background Art

[0002] The existing methods for treating fluoride-containing wastewater in the semiconductor industry mainly include chemical precipitation, coagulation precipitation, adsorption and crystallization. Among them, the chemical precipitation method is to add chemical agents to the fluoride-containing wastewater to form precipitation between fluoride ions and precipitants (lime, calcium chloride, calcium carbonate, etc.), and then remove fluorine after solid-liquid separation. The two-stage defluorination process with chemical precipitation as the core, namely "primary reaction + primary flocculation + primary precipitation + secondary reaction + secondary flocculation + secondary precipitation", is currently widely used in the treatment of large-scale high-concentration fluoride-containing wastewater due to its simple operation, low investment and obvious defluorination effect. The COD value of the wastewater after defluorination is still very high, and it needs to enter the biochemical and membrane separation system for further treatment to meet the discharge standards. The main disadvantages of the existing two-stage defluorination process are: (1) The calcium fluoride generated by the reaction is wrapped around the surface of the precipitant particles, hindering the further reaction of the precipitant inside the particles, reducing the efficiency of the precipitant, increasing the amount of precipitant used and the amount of sludge, and at the same time, the unreacted precipitant and residual calcium fluoride affect the stable operation of the subsequent biochemical treatment system. This is because high concentrations of calcium ions are inhibitors of activated sludge, and it is usually necessary to continuously inoculate activated sludge to maintain the normal operation of the biochemical treatment system. In addition, calcium fluoride is a membrane pollutant that is extremely difficult to clean, which can easily cause membrane blockage and reduce membrane separation efficiency.

[0003] (2) During the precipitation reaction, it is necessary to control the pH of the wastewater to be in the range of 9 to 12 by adding alkali to facilitate the formation of calcium fluoride. After the reaction is completed, it is necessary to adjust the pH of the wastewater to 6 to 9 by adding acid to meet the requirements of the subsequent biochemical treatment system. Therefore, a large amount of acid and alkali reagents are used.

[0004] (3) Wastewater is rich in phosphorus. The existing two-stage defluorination process has a low phosphorus recovery rate. The unrecovered phosphorus enters the biochemical treatment system, increasing the load of the biochemical treatment and causing a waste of phosphorus resources.

[0005] (4) The existing technology mainly uses precipitation method for phosphorus removal. The pH value of the wastewater after the two-stage defluorination process is relatively low. When the precipitation method is used for phosphorus removal, it is necessary to control the pH value to 9-10 by adding alkali to facilitate the formation of calcium phosphate. After the reaction, it is necessary to control the pH value to 6-9 by adding acid to meet the requirements of the subsequent treatment system or discharge. The amount of acid and alkali reagents used is relatively large. Summary of the invention

[0006] In order to solve the technical problems of large amount of precipitant and reagent usage, low phosphorus recovery rate and unstable operation of subsequent biochemical treatment system in the existing fluorine-containing wastewater treatment process, the present invention provides a semiconductor industry fluorine-containing wastewater treatment system and method.

[0007] The technical solution adopted by the present invention is: A semiconductor industry fluorine-containing wastewater treatment system, comprising: A regulating unit is used to balance the quality and quantity of incoming water; The pretreatment unit is used to add chemical agents to the conditioned wastewater to cause fluoride ions to form precipitation with the precipitant, and then discharge it from the system in the form of physical and chemical sludge after solid-liquid separation to achieve fluoride removal; The phosphorus recovery unit is used to add a precipitant to the pretreated wastewater to make the phosphorus ions form phosphate precipitation, which is discharged from the system in the form of physical and chemical sludge after solid-liquid separation, so as to achieve further fluorine removal and phosphorus recovery; A biochemical treatment and membrane separation unit for removing organic matter from the wastewater after phosphorus recovery through microbial degradation and membrane separation; and The phosphorus release and calcium removal unit is used to release the phosphorus in the membrane separation concentrated water and enter the phosphorus recovery unit together with the partially hydrolyzed acidified water from the biochemical treatment and membrane separation units after cyclone enrichment, so that the calcium fluoride and calcium phosphate remaining in the biochemical system are removed from the system in the form of physical and chemical sludge.

[0008] Furthermore, the regulating unit comprises a regulating tank, a first aeration device is provided at the bottom of the regulating tank, and the first aeration device is connected to the biochemical aeration main pipe of the biochemical treatment and membrane separation unit.

[0009] Furthermore, the pretreatment unit comprises a mixing reaction tank, a coagulation reaction tank, a flocculation reaction tank and a sedimentation tank which are connected in sequence, and part of the sludge in the sedimentation tank is discharged, and part of it is returned to the flocculation reaction tank.

[0010] Furthermore, a dosing device for alkali solution and precipitant is provided in the mixing reaction tank, and a second aeration device is provided at the bottom of the coagulation reaction tank. The second aeration device is connected to the membrane scrubbing aeration main pipe of the biochemical treatment and membrane separation unit.

[0011] Furthermore, the phosphorus recovery unit includes a phosphorus recovery tank and a mixing buffer tank. The phosphorus recovery tank is provided with a precipitant dosing device. After solid-liquid separation in the phosphorus recovery tank, part of the precipitated sludge is discharged to recover phosphorus, and part of it is merged with the sludge in the sedimentation tank of the pretreatment unit; the supernatant of the sedimentation separation enters the mixing buffer tank.

[0012] Furthermore, a sulfuric acid dosing device and a stirrer are provided in the mixing buffer tank.

[0013] Furthermore, the biochemical treatment and membrane separation unit includes a hydrolysis acidification tank, an anoxic tank, an aerobic tank and an MBR membrane tank which are connected in sequence; part of the effluent from the hydrolysis acidification tank is pumped into the phosphorus release unit and enters the phosphorus recovery unit together with the wastewater from the phosphorus release unit to recover phosphorus.

[0014] Furthermore, a domestic sewage inlet pipe is provided in the hydrolysis acidification tank. Domestic sewage is rich in phosphorus, and biochemical treatment together with defluorinated wastewater can improve the efficiency of phosphorus recovery. In addition, continuous inoculation of defluorinated wastewater with sludge using domestic sewage can reduce the inhibition of high-concentration calcium ions on activated sludge and maintain the normal operation of the biochemical treatment system.

[0015] Furthermore, the phosphorus release and calcium removal unit includes a reflow tank, a mud phase enrichment cyclone, a biological phosphorus release tank and a water phase enrichment cyclone; the membrane separation concentrated water enters the reflow tank and is pumped to the mud phase enrichment cyclone for centrifugal separation, the separated light components are discharged as biological sludge, and the heavy components enter the biological phosphorus release tank; the mud water in the biological phosphorus release tank is pumped together with the partially hydrolyzed acidified water of the biochemical treatment and membrane separation unit to the water phase enrichment cyclone for centrifugal separation, the separated light components enter the anoxic tank of the biochemical treatment and membrane separation unit, and the heavy components enter the phosphorus recovery unit together with the effluent of the pretreatment unit.

[0016] A method for using any one of the above semiconductor industry fluorine-containing wastewater treatment systems comprises the following steps: (1) After the fluorine-containing wastewater is regulated in water quality and quantity by the regulating unit, it enters the pretreatment unit; (2) In the pretreatment unit, the wastewater is first mixed with NaOH and CaCl2, and then subjected to coagulation and flocculation followed by sedimentation separation. During this process, fluoride ions form calcium fluoride sludge, which is discharged in the form of physical and chemical sludge, and the supernatant of sedimentation separation enters the phosphorus recovery unit; (3) In the phosphorus recovery unit, fluoride ions are further removed by adding CaCl2 precipitant to the wastewater, and the phosphorus ions in the wastewater react with CaCl2 to form calcium phosphate precipitates. Phosphorus is recovered after solid-liquid separation, and calcium fluoride sludge is discharged in the form of physical and chemical sludge. The supernatant of sedimentation separation is adjusted with H2SO4 to adjust the pH value and enter the biochemical treatment and membrane separation unit; (4) In the biochemical treatment and membrane separation unit, the wastewater undergoes hydrolysis, acidification, anoxic treatment, and aerobic treatment in sequence, and then passes through the MBR membrane to separate organic matter, harmful substances, and salt, and is discharged in compliance with the standards; the membrane separation concentrate enters the phosphorus release unit; (5) In the phosphorus release and calcium removal unit, the calcium fluoride and calcium phosphate remaining in the biochemical system are enriched by using a mud phase enrichment cyclone and then sent to the biological phosphorus release tank. The biological phosphorus release tank releases the phosphorus in the mud water, which is then combined with the partially hydrolyzed acidified water from the biochemical treatment and membrane separation units and then enriched by the water phase enrichment cyclone before entering the phosphorus recovery unit.

[0017] Beneficial effects of the present invention: By setting up a phosphorus recovery unit between the pretreatment unit and the biochemical treatment and membrane separation unit, the high pH of the effluent from the sedimentation tank of the pretreatment unit can be directly used for precipitation and phosphorus removal, reducing the amount of alkali added, and only one acid needs to be added for pH adjustment after phosphorus removal, reducing the amount of acid added, thereby greatly reducing the amount of acid and alkali agents used in the entire system.

[0018] 2. Through the combination of the phosphorus recovery unit and the phosphorus release and calcium removal unit, the phosphorus release and calcium removal unit can enrich the calcium fluoride and calcium phosphate remaining in the biochemical system and enter the phosphorus recovery unit, and finally remove them from the system in the form of physical and chemical sludge and phosphorus products, thereby reducing the impact of calcium ions on the MBR membrane; the phosphorus recovery unit uses the high pH value of the pretreatment unit, and uses the unprecipitated calcium fluoride, newly generated calcium fluoride, and calcium phosphate and calcium fluoride refluxed from the phosphorus release and calcium removal unit as crystal nuclei to induce the calcium ions and phosphate ions in the wastewater to quickly form calcium fluoride and calcium phosphate, which are finally removed from the system by physical and chemical sludge discharge and phosphorus product recovery, thereby improving the phosphorus recovery rate, reducing the amount of precipitant used and the amount of sludge, and ensuring the stable operation of the biochemical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a flow chart of the fluorine-containing wastewater treatment system of Example 1 of the present invention.

[0020] In the figure: 100 regulating unit, 200 pretreatment unit, 300 phosphorus recovery unit, 400 membrane separation unit, 500 phosphorus release and calcium removal unit, 1 regulating tank, 2 mixing reaction tank, 3 coagulation reaction tank, 4 flocculation reaction tank, 5 sedimentation tank, 6 phosphorus recovery tank, 7 mixing buffer tank, 8 hydrolysis acidification tank, 9 membrane grid, 10 anoxic tank, 11 aerobic tank, 12 MBR membrane tank, 13 reflow tank, 14 water phase enrichment cyclone, 15 biological phosphorus release tank, 16 mud phase enrichment cyclone, 17 biochemical aeration fan, 18 membrane scrubbing fan. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the present invention more clear, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and a preferred implementation manner. Example 1

[0022] See also Figure 1 This embodiment provides a semiconductor industrial fluorine-containing wastewater treatment system, including a regulating unit 100, a pretreatment unit 200, a phosphorus recovery unit 300, a biochemical treatment and membrane separation unit 400, and a phosphorus release and calcium removal unit 500.

[0023] The regulating unit 100 includes a regulating tank 1. In this embodiment, a first aeration device is provided at the bottom of the regulating tank 1, and the first aeration device includes an aerator and an aeration branch pipe. The aeration branch pipe is connected to the biochemical aeration main pipe of the biochemical treatment and membrane separation unit 400 through an aeration valve.

[0024] The effluent from the regulating tank 1 flows by gravity into the mixing reaction tank 2.

[0025] The pretreatment unit 200 includes a mixing reaction tank 2, a coagulation reaction tank 3, a flocculation reaction tank 4 and a sedimentation tank 5 which are connected in sequence.

[0026] The mixing reaction tank 2 is provided with sodium hydroxide and calcium chloride reagent dosing points, the main functions of which are to add alkali to adjust the pH and add precipitants to promote the reaction of fluoride ions and calcium ions in the wastewater to generate calcium fluoride.

[0027] In this embodiment, a second aeration device and a stirrer are also provided in the mixing reaction tank 2. The second aeration device includes an aerator and an aeration branch pipe. The aeration branch pipe is connected to the membrane scrubbing aeration main pipe of the biochemical treatment and membrane separation unit 400 through an aeration valve, and the high air volume of the membrane scrubbing aeration is used to intermittently flush the calcium fluoride particles generated by the reaction to prevent them from being wrapped on the surface of the precipitant particles, thereby improving the use efficiency of the precipitant and reducing the use amount of the precipitant and the amount of sludge.

[0028] A coagulant addition point is provided in the coagulation reaction tank 3, the main function of which is to add coagulant so that calcium fluoride and coagulant react fully to form flocs, which is conducive to sedimentation and separation.

[0029] A flocculant addition point is provided in the flocculation reaction tank 4, the main function of which is to add flocculants so that calcium fluoride and the flocculants react fully to form flocs, which is beneficial to sedimentation and separation.

[0030] The main function of the sedimentation tank 5 is to perform sedimentation separation, and remove the flocs rich in calcium fluoride from the system by sedimentation. After sedimentation separation, the supernatant overflows into the phosphorus recovery tank 6, the sludge part flows back to the flocculation reaction tank 4, and the remaining sludge is discharged to the physical and chemical sludge treatment unit.

[0031] The phosphorus recovery unit 300 includes a phosphorus recovery tank 6 and a mixing buffer tank 7 .

[0032] The phosphorus recovery tank 6 is provided with a calcium chloride dosing point, the main functions of which are: (1) further removing fluorine by secondary dosing of calcium chloride; (2) using the calcium fluoride that has not been completely precipitated in the sedimentation tank and the calcium fluoride generated by the newly added calcium chloride to provide crystal nuclei to induce the rapid formation of calcium fluoride; (3) using the high pH of the sedimentation tank to precipitate calcium phosphate in the wastewater to recover phosphorus in the wastewater; (4) using the calcium phosphate refluxed from the phosphorus release and calcium removal unit 500 to provide crystal nuclei to induce the rapid formation of calcium phosphate.

[0033] After pretreatment, the wastewater is separated into solid and liquid in the phosphorus recovery tank 6, the supernatant flows into the mixing buffer tank 7 by gravity, the sludge part flows back to the sludge return pipeline of the sedimentation tank 5, and the remaining part is discharged to the phosphorus product recovery unit to recover phosphorus. The calcium phosphate and calcium fluoride rich in the return sludge serve as crystal nuclei to enhance the reaction effect of the flocculation reaction tank.

[0034] A sulfuric acid addition point is provided in the mixing buffer tank 7, the main function of which is to add sulfuric acid to neutralize the high pH caused by the addition of sodium hydroxide in the mixing reaction tank, so as to ensure the normal operation of the biochemical system.

[0035] The biochemical treatment and membrane separation unit 400 includes a hydrolysis acidification tank 8, a membrane grid 9, an anoxic tank 10, an aerobic tank 11, an MBR membrane tank 12, a biochemical aeration fan 17 and a membrane scrubbing fan 18 connected in sequence. The anoxic tank / aerobic tank / membrane tank / reflow tank and aeration system are designed according to conventional processes. The water in the hydrolysis acidification tank 8 is partially pumped into the water phase enrichment cyclone 14.

[0036] In addition, a domestic sewage inlet may be provided in the hydrolysis acidification tank 8. By introducing domestic sewage, the influence of inhibitors such as calcium ions on the biochemical treatment system is reduced, and the operating cost of continuous inoculation is reduced or eliminated. At the same time, the phosphorus content of domestic sewage sludge is relatively high, which improves the operating efficiency of the phosphorus recovery unit.

[0037] The produced water of the MBR membrane pool 12 is discharged, and the concentrated water enters the reflow pool 13.

[0038] The phosphorus release and decalcification unit 500 includes a reflow tank 13 , a mud phase enrichment cyclone 16 , a biological phosphorus release tank 15 and a water phase enrichment cyclone 14 .

[0039] The effluent from the reflow tank 13 is pumped into the mud phase enrichment cyclone 16 , the light components overflowing from the top of the mud phase enrichment cyclone are discharged to the biological sludge treatment system, and the heavy components at the bottom flow by gravity into the biological phosphorus release tank 15 .

[0040] The functions of the mud phase enrichment cyclone 16 are: (1) to enrich the calcium fluoride and calcium phosphate remaining in the biochemical system, and finally remove them from the system by physical and chemical sludge discharge and phosphorus product recovery, thereby reducing the impact of calcium fluoride and calcium phosphate on the MBR membrane; (2) to increase the sludge concentration, improve the sludge concentration and phosphorus release effect of the biological phosphorus release tank.

[0041] The function of the biological phosphorus release pool 15 is: under the anaerobic state without dissolved oxygen and nitrate nitrogen, facultative bacteria convert dissolved organic matter into volatile fatty acids, so that the phosphorus removal bacteria obtain volatile fatty acids. The phosphorus removal bacteria absorb the volatile fatty acids produced in the anaerobic microbial phosphorus release pool and transport them into the cells, assimilate them into fermentation of intracellular sugars, and cause the release of phosphorus.

[0042] The effluent from the biological phosphorus release tank is pumped together with the effluent from the hydrolysis and acidification tank into the water phase enrichment cyclone 14. The light components separated by the water phase enrichment cyclone 14 are returned to the anoxic tank 10 to promote denitrification and denitrification as a biological internal carbon source; the separated heavy components enter the phosphorus recovery tank 6 together with the effluent from the sedimentation tank, so that the calcium fluoride and calcium phosphate remaining in the biochemical system are enriched and finally removed from the system through physical and chemical sludge discharge and phosphorus product recovery. Example 2

[0043] This embodiment provides a method for treating fluoride-containing wastewater using the treatment system described in Example 1, wherein the fluoride ion concentration in the fluoride-containing wastewater is 30 mg / L and the total phosphorus concentration is 6 mg / L: (1) Fluoride-containing wastewater enters regulating tank 1, and after adjusting the water quality and water volume, it enters mixing reaction tank 2; the hydraulic retention time of the regulating tank is 6~12h; (2) In the mixed reaction tank 2, react with NaOH and CaCl2. The hydraulic retention time of the mixed reaction tank 2 is 3~5min, and the pH is 9~12. The molar ratio of calcium ions in the calcium salt added in the mixed reaction tank to fluoride ions in the wastewater is 0.6~0.8. After the reaction is completed, it enters the coagulation reaction tank 3 and the flocculation reaction tank 4 in turn. The hydraulic retention time of the coagulation reaction tank 3 is 3~5min. The dosage of the coagulant polyaluminium chloride (PAC) is 100~300 mg / L, and the hydraulic retention time of the flocculation reaction tank 4 is 3~5min. The dosage of the flocculant anionic polyacrylamide (PAM) is 1~5 mg / L.

[0044] (3) After coagulation and flocculation, the wastewater enters the sedimentation tank 5 for sedimentation separation. The supernatant of the sedimentation separation enters the phosphorus recovery tank 6. The sludge part is returned to the flocculation reaction tank 4, and the remaining sludge is discharged to the physical and chemical sludge treatment unit. The return ratio of the sludge return from the sedimentation tank is 20-50%. The surface load of the sedimentation tank 5 is 5-10 m 3 / (m 2 ·h), hydraulic retention time is 10~30 min.

[0045] Through the above steps, it is detected that the concentration of fluoride ions in the wastewater entering the phosphorus recovery tank 6 is reduced to below 10 mg / L.

[0046] (4) The pH of the wastewater entering the phosphorus recovery tank 6 is 9-12. The unreacted fluoride ions in the wastewater react with the newly added CaCl2 precipitant to form calcium fluoride sludge; the phosphorus ions in the wastewater react with CaCl2 under alkaline conditions to form calcium phosphate sludge. After solid-liquid separation, part of the sludge is returned to the sludge return pipeline of the sedimentation tank 5, and the remaining part is discharged to the phosphorus product recovery unit to recover phosphorus. The reflux ratio is 10-20%. The molar ratio of Ca ions in the calcium chloride reagent added to the phosphorus recovery tank 6 to phosphate ions in the wastewater is 3-5; the supernatant of the sedimentation separation flows into the mixing buffer tank 7 by gravity. The fluoride ion concentration in the supernatant is detected to be reduced to below 1.5 mg / L, and the phosphate concentration is reduced to below 0.3 mg / L; (5) The wastewater entering the mixing buffer tank 7 is adjusted with H2SO4 to adjust the pH value and then enters the hydrolysis acidification tank 8. The hydraulic retention time of the mixing reaction tank is 3-5 minutes, and the pH value of the effluent from the mixing reaction tank is 6-9; (6) The wastewater entering the hydrolysis acidification tank 8 is pumped into the water phase enrichment cyclone 14, and the rest is filtered through the membrane grid 9 and then enters the anoxic tank 10, the aerobic tank 11, and the MBR membrane tank 12 in sequence. The amount of acidified water entering the water phase enrichment cyclone 14 accounts for 20% to 50% of the total amount of water entering the hydrolysis acidification tank. The hydraulic retention time of the hydrolysis acidification tank is 6h to 12h; the produced water of the MBR membrane tank 12 is discharged, and the concentrated water enters the recirculation tank 13; (7) The effluent from the reflow tank 13 is pumped into the mud phase enrichment cyclone 16. The light components overflowing from the top of the mud phase enrichment cyclone are discharged to the biological sludge treatment system, and the heavy components at the bottom flow by gravity into the biological phosphorus release tank 15. The hydraulic retention time of the biological phosphorus release tank is 1~5h, and the ORP value is ≤-250mV; the effluent from the biological phosphorus release tank 15 is pumped together with the effluent from the hydrolysis acidification tank into the liquid phase enrichment cyclone 14. The light components separated by the water phase enrichment cyclone 14 are returned to the anoxic tank 10, and the heavy components enter the phosphorus recovery tank 6 together with the effluent from the sedimentation tank. The separation pressure of the mud phase enrichment cyclone 16 and the water phase enrichment cyclone 14 is 0.1~0.4 MPa.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications are also within the protection scope of the present invention.

Claims

1. A semiconductor industry fluorine-containing wastewater treatment system, characterized in that: include: A regulating unit is used to balance the quality and quantity of incoming water; The pretreatment unit is used to add chemical agents to the conditioned wastewater to cause fluoride ions to form precipitation with the precipitant, and then discharge it from the system in the form of physical and chemical sludge after solid-liquid separation to achieve fluoride removal; The phosphorus recovery unit is used to add a precipitant to the pretreated wastewater to make the phosphorus ions form phosphate precipitation, which is discharged from the system in the form of physical and chemical sludge after solid-liquid separation, so as to achieve further fluorine removal and phosphorus recovery; Biochemical treatment and membrane separation unit, used to remove organic matter in wastewater after phosphorus recovery through microbial degradation and membrane separation; as well as The phosphorus release and calcium removal unit is used to release the phosphorus in the membrane separation concentrated water and enter the phosphorus recovery unit together with the partially hydrolyzed acidified water from the biochemical treatment and membrane separation units after cyclone enrichment, so that the calcium fluoride and calcium phosphate remaining in the biochemical system are removed from the system in the form of physical and chemical sludge.

2. A semiconductor industry fluorine-containing wastewater treatment system according to claim 1, characterized in that: The regulating unit comprises a regulating tank (1), the bottom of which is provided with a first aeration device, the first aeration device being connected to the biochemical aeration main pipe of the biochemical treatment and membrane separation unit.

3. A semiconductor industry fluorine-containing wastewater treatment system according to claim 1, characterized in that: The pretreatment unit comprises a mixing reaction tank (2), a coagulation reaction tank (3), a flocculation reaction tank (4) and a sedimentation tank (5) which are connected in sequence. Part of the sludge in the sedimentation tank is discharged, and part of it flows back to the flocculation reaction tank (4).

4. A semiconductor industry fluorine-containing wastewater treatment system according to claim 3, characterized in that: An alkali solution and precipitant dosing device is provided in the mixing reaction tank (2), and a second aeration device is provided at the bottom of the coagulation reaction tank (3). The second aeration device is connected to the membrane scrubbing aeration main pipe of the biochemical treatment and membrane separation unit.

5. A semiconductor industry fluorine-containing wastewater treatment system according to claim 1, characterized in that: The phosphorus recovery unit comprises a phosphorus recovery tank (6) and a mixing buffer tank (7). A precipitant dosing device is provided in the phosphorus recovery tank (6). After solid-liquid separation in the phosphorus recovery tank, part of the precipitated sludge is discharged to recover phosphorus, and part of it is combined with the sludge in the sedimentation tank of the pretreatment unit. The supernatant after sedimentation separation enters the mixing buffer tank (7).

6. A semiconductor industry fluorine-containing wastewater treatment system according to claim 5, characterized in that: A sulfuric acid dosing device and a stirrer are provided in the mixing buffer tank (7).

7. A semiconductor industry fluorine-containing wastewater treatment system according to claim 1, characterized in that: The biochemical treatment and membrane separation unit comprises a hydrolysis acidification tank (8), an anoxic tank (10), an aerobic tank (11) and an MBR membrane tank (12) which are connected in sequence; part of the effluent from the hydrolysis acidification tank (8) is pumped into the phosphorus release unit and enters the phosphorus recovery unit together with the wastewater from the phosphorus release unit to recover phosphorus.

8. A semiconductor industry fluorine-containing wastewater treatment system according to claim 7, characterized in that: A domestic sewage inlet pipe is provided in the hydrolysis acidification tank (8).

9. A semiconductor industry fluorine-containing wastewater treatment system according to claim 1, characterized in that: The phosphorus release and calcium removal unit comprises a reflow tank (13), a mud phase enrichment cyclone (16), a biological phosphorus release tank (15) and a water phase enrichment cyclone (14); the membrane separation concentrated water enters the reflow tank (13), is pumped to the mud phase enrichment cyclone (16) for centrifugal separation, the separated light components are discharged as biological sludge, and the heavy components enter the biological phosphorus release tank (15); the mud water in the biological phosphorus release tank (15) is pumped together with the partially hydrolyzed acidified water of the biochemical treatment and membrane separation unit to the water phase enrichment cyclone (14) for centrifugal separation, the separated light components enter the anoxic tank of the biochemical treatment and membrane separation unit, and the heavy components enter the phosphorus recovery unit together with the effluent of the pretreatment unit.

10. A method for treating semiconductor industrial fluorine-containing wastewater using the system described in any one of claims 1 to 9, characterized in that: The steps include: (1) After the fluorine-containing wastewater is regulated in water quality and quantity by the regulating unit, it enters the pretreatment unit; (2) In the pretreatment unit, the wastewater is first mixed with NaOH and CaCl2, and then subjected to coagulation and flocculation followed by sedimentation separation. During this process, fluoride ions form calcium fluoride sludge, which is discharged in the form of physical and chemical sludge, and the supernatant of sedimentation separation enters the phosphorus recovery unit; (3) In the phosphorus recovery unit, fluoride ions are further removed by adding CaCl2 precipitant to the wastewater, and the phosphorus ions in the wastewater react with CaCl2 to form calcium phosphate precipitates. Phosphorus is recovered after solid-liquid separation, and calcium fluoride sludge is discharged in the form of physical and chemical sludge. The supernatant of sedimentation separation is adjusted with H2SO4 to adjust the pH value and enter the biochemical treatment and membrane separation unit; (4) In the biochemical treatment and membrane separation unit, the wastewater undergoes hydrolysis, acidification, anoxic treatment, and aerobic treatment in sequence, and then passes through the MBR membrane to separate organic matter, harmful substances, and salt, and is discharged in compliance with the standards; the membrane separation concentrate enters the phosphorus release unit; (5) In the phosphorus release and calcium removal unit, the calcium fluoride and calcium phosphate remaining in the biochemical system are enriched by using a mud phase enrichment cyclone and then sent to the biological phosphorus release tank. The biological phosphorus release tank releases the phosphorus in the mud water, which is then combined with the partially hydrolyzed acidified water from the biochemical treatment and membrane separation units and enriched by the water phase enrichment cyclone before entering the phosphorus recovery unit.

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