Fluorine-containing wastewater discharge method and system

Abstract

The invention belongs to the field of water treatment, and provides a fluorine-containing wastewater discharge method and system.The fluorine-containing wastewater discharge method can divide fluorine-containing wastewater into first-class wastewater and second-class wastewater based on the pH value, the first-class wastewater is pretreated, the pH value of the first-class wastewater is regulated, and the second-class wastewater is discharged; the first type of wastewater after pH value regulation is separated into standard recovery water and a fluorine-containing concentrated solution by using a filtering membrane system, the fluorine-containing concentrated solution and the second type of wastewater are mixed into mixed wastewater, and the mixed wastewater is separated into standard discharge water and fluorine-containing precipitates in a physicochemical precipitation treatment mode. According to the scheme, treatment can be carried out more accurately according to the characteristics of different wastewater, the treatment efficiency can be improved, the burden of a filter membrane system and a precipitation process is reduced, the influence of the fluorine-containing wastewater on the environment is greatly reduced by removing pollutants in the fluorine-containing wastewater, the risks of water source pollution and soil pollution are reduced, and the method is suitable for popularization and application. Meanwhile, wastewater recycling is achieved, the treatment cost is reduced, and resource waste is avoided.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a method and system for discharging fluoride-containing wastewater. Background Technology

[0002] Fluoride-containing wastewater is generated during industrial production processes such as fluorochemicals, aluminum smelting, glass manufacturing, pharmaceuticals, and cement. Fluoride ions are highly toxic and bioaccumulative. If discharged directly without effective treatment, it will cause serious pollution to water bodies, soil, and the ecological environment, and may even pose long-term harm to human health.

[0003] Existing methods for treating fluoride-containing wastewater mainly include chemical precipitation, adsorption, ion exchange, and membrane separation. However, current methods cannot specifically treat fluoride-containing wastewater with different characteristics, placing a heavy burden on the overall treatment system.

[0004] In addition, fluoride-containing wastewater treatment systems often suffer from problems such as large equipment size, slow sedimentation and settling, and difficulty in dehydration, resulting in high wastewater treatment costs and low treatment efficiency. They are unable to effectively recover resources and are prone to inadequate treatment. The discharge of inadequately treated fluoride-containing wastewater may further lead to water pollution, soil pollution and ecological risks. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention proposes a method for discharging fluoride-containing wastewater, the method comprising: Based on pH value, fluoride-containing wastewater is classified into Class I wastewater and / or Class II wastewater; The first type of wastewater is pretreated and its pH value is adjusted. The first type of wastewater after pH adjustment is separated into qualified recycled water and fluoride concentrate using a filtration membrane system. The fluoride concentrate is mixed with the second type of wastewater to form mixed wastewater, and the mixed wastewater is separated into compliant discharge water and fluoride precipitate through physicochemical precipitation treatment.

[0006] Specifically, the filtration membrane system includes at least two stages of filtration membrane units. The separation of the first type of wastewater, after pH adjustment, into compliant reclaimed water and a fluoride-containing concentrate using the filtration membrane system includes: The first type of wastewater after pH adjustment is identified as the liquid to be filtered, and the liquid to be filtered is separated into filtered liquid and fluoride concentrate by the current filtration membrane unit. The concentration of fluoride ions in the filtered liquid obtained by separation is detected. If the concentration of fluoride ions in the filtered liquid is lower than the preset concentration threshold, the filtered liquid is determined to be qualified recycled water. If the fluoride ion concentration in the filtered liquid is not lower than the concentration threshold, the filtered liquid is redefined as the liquid to be filtered and passed to the next stage filtration membrane unit. The step of "separating the liquid to be filtered into filtered liquid and fluoride concentrate through the current filtration membrane unit" is performed again until the fluoride ion concentration in the filtered liquid is lower than the concentration threshold.

[0007] Furthermore, the method also includes: If the concentration of fluoride ions in the currently separated filtered liquid is lower than the concentration threshold, the currently separated fluoride concentrate is reclassified as the liquid to be filtered and transferred to the next-level filtration membrane unit, and the step of "separating the liquid to be filtered into the filtered liquid and the fluoride concentrate through the current filtration membrane unit" is executed again.

[0008] Specifically, the pretreatment of the first type of wastewater is achieved through a catalytic unit; The first type of wastewater includes alkaline wastewater and acidic wastewater with a pH value not less than a first preset value, and the second type of wastewater includes acidic wastewater with a pH value less than the first preset value.

[0009] Optionally, the pretreatment of the first type of wastewater and the adjustment of its pH value include: The first type of wastewater is passed to the catalytic unit for pretreatment, and the pH value of the pretreated first type of wastewater is adjusted by the pH control unit. The pilot filtration membrane unit in the filtration membrane system pre-filters alkaline wastewater with a pH value greater than the second preset value in the first type of wastewater. Acidic wastewater, alkaline wastewater with a pH value not greater than the second preset value, and / or alkaline wastewater passing through the pilot filtration membrane unit are then transferred to the catalytic unit for pretreatment. The pH value of the pretreated first type of wastewater is then adjusted by the pH control unit. And / or, the alkaline wastewater in the first type of wastewater is pre-filtered through the pilot filtration membrane unit, the alkaline wastewater passing through the pilot filtration membrane unit is transferred to the catalytic unit for pretreatment, and the pH value of the pretreated alkaline wastewater and / or the acidic wastewater in the first type of wastewater is adjusted through the pH control unit.

[0010] Preferably, the method of adjusting the pH value of the first type of wastewater includes: The pH value of the first type of wastewater is continuously monitored, and a control signal for adding control liquid to the first type of wastewater is generated based on the current monitoring results. The current delay time is determined by the length of the transport path of the control liquid and the current transport flow rate of the control liquid. The process of repeatedly updating the control signal based on the current detection results and the current delay time, and re-determining the current delay time, is performed to continuously update the delivery flow rate of the control liquid until the pH value of the first type of wastewater reaches the target value, at which point a stop signal is generated to stop adding the control liquid to the first type of wastewater.

[0011] Furthermore, the method also includes: The fluoride-containing concentrate obtained from the separation is tested under preset detection conditions; If the fluoride concentrate meets the detection conditions, the fluoride concentrate is reclassified as alkaline wastewater in the first type of wastewater, and the step of "pre-filtering the alkaline wastewater in the first type of wastewater through the pilot filtration membrane unit" is performed.

[0012] Specifically, the separation of the mixed wastewater into compliant reclaimed water and fluoride-containing precipitates through physicochemical precipitation is achieved through at least two reaction units and at least two precipitation units. The primary reaction unit is connected to the mixing unit for mixing the fluoride concentrate and the second type of wastewater. Each reaction unit at each level is connected to the sedimentation unit at the same level. All reaction units except the primary reaction unit at each level are connected to the sedimentation unit at the previous level. Any one-stage reaction unit is used to defluorinate the liquid transferred from the mixing unit or the previous stage precipitation unit. Each stage precipitation unit is used to generate fluoride-containing precipitates, and the last stage precipitation unit is used to obtain the qualified discharge water after the fluoride-containing precipitates have settled.

[0013] Furthermore, the method also includes: After the alkaline wastewater is pre-filtered by the pilot filtration membrane unit, the alkaline wastewater that has not passed through the pilot filtration membrane unit is transferred to the mixing unit to be mixed with the second type of wastewater and / or the fluoride-containing concentrate, and / or transferred to a designated reaction unit for defluorination reaction.

[0014] The present invention also proposes a fluoride-containing wastewater discharge system, the system comprising: A classification module is used to classify fluoride-containing wastewater into Class I wastewater and / or Class II wastewater based on pH value; The wastewater reduction module includes a filtration membrane system for pretreating the first type of wastewater and adjusting the pH value of the first type of wastewater. The filtration membrane system is used to separate the first type of wastewater after pH adjustment into compliant recycled water and fluoride concentrate. The physicochemical precipitation module is used to mix the fluoride-containing concentrate with the second type of wastewater to form mixed wastewater, and then separate the mixed wastewater into compliant discharge water and fluoride-containing precipitates through physicochemical precipitation treatment.

[0015] Specifically, the filtration membrane system includes at least two stages of filtration membrane units, and the wastewater reduction module includes: A separation unit is used to identify the first type of wastewater after pH adjustment as the liquid to be filtered, and to separate the liquid to be filtered into filtered liquid and fluoride concentrate through the current filtration membrane unit. The concentration detection unit is used to detect the concentration of fluoride ions in the currently separated filtered liquid. If the concentration of fluoride ions in the filtered liquid is lower than the preset concentration threshold, the filtered liquid is determined to be qualified recycled water. The first transfer unit is used to re-determine the filtered liquid as the liquid to be filtered and transfer it to the next stage filtration membrane unit when the fluoride ion concentration in the filtered liquid is not lower than the concentration threshold, so that the separation unit performs the step of "separating the liquid to be filtered into filtered liquid and fluoride concentrate through the current filtration membrane unit" again until the fluoride ion concentration in the filtered liquid is lower than the concentration threshold. The first transfer unit is further configured to, when the concentration of fluoride ions in the currently separated filtered liquid is lower than the concentration threshold, re-determine the currently separated fluorine-containing concentrate as the liquid to be filtered and transfer it to the next-level filtration membrane unit, so that the separation unit performs the step of "separating the liquid to be filtered into the filtered liquid and the fluorine-containing concentrate through the current filtration membrane unit" again.

[0016] Specifically, the wastewater reduction module also includes: A catalytic unit is used to pretreat the first type of wastewater; the first type of wastewater includes alkaline wastewater and acidic wastewater with a pH value not less than a first preset value, and the second type of wastewater includes acidic wastewater with a pH value less than the first preset value.

[0017] Optionally, the wastewater reduction module further includes: A control unit is used to transfer the first type of wastewater to the catalytic unit for pretreatment and to control the pH value of the first type of wastewater after pretreatment. The pilot filtration membrane unit in the filtration membrane system pre-filters alkaline wastewater with a pH value greater than the second preset value in the first type of wastewater. Acidic wastewater, alkaline wastewater with a pH value not greater than the second preset value, and / or alkaline wastewater passing through the pilot filtration membrane unit are then transferred to the catalytic unit for pretreatment. The pH value of the pretreated first type of wastewater is then adjusted. And / or, the alkaline wastewater in the first type of wastewater is pre-filtered through the pilot filtration membrane unit, the alkaline wastewater passing through the pilot filtration membrane unit is transferred to the catalytic unit for pretreatment, and the pH value of the pretreated alkaline wastewater and / or the acidic wastewater in the first type of wastewater is adjusted.

[0018] Preferably, the wastewater reduction module further includes: The delay detection unit is used to continuously detect the pH value of the first type of wastewater, generate a control signal for adding control liquid to the first type of wastewater based on the current detection result, and determine the current delay time by the length of the transport path of the control liquid and the current transport flow rate of the control liquid. The delivery adjustment unit is used to cause the delay detection unit to repeatedly perform the steps of updating the control signal based on the current detection result and the current delay time and re-determining the current delay time, so as to continuously update the delivery flow rate of the control liquid until the pH value of the first type of wastewater is detected to reach the target value, and then generate a stop signal to stop adding the control liquid to the first type of wastewater.

[0019] Furthermore, the wastewater reduction module also includes: The second transfer unit is used to detect the currently separated fluoride concentrate under preset detection conditions, and when the fluoride concentrate meets the detection conditions, to reclassify the fluoride concentrate as alkaline wastewater in the first type of wastewater, and to cause the control unit to perform the step of "pre-filtering the alkaline wastewater in the first type of wastewater through the pilot filtration membrane unit".

[0020] Specifically, the physicochemical precipitation module includes a mixing unit, at least two stages of reaction units, and at least two stages of precipitation units; The mixing unit is used to mix the fluoride concentrate with the second type of wastewater. The primary reaction unit is connected to the mixing unit. Each level of reaction unit is connected to the same level of precipitation unit. Except for the primary reaction unit, each level of reaction unit is connected to the previous level of precipitation unit. Any one-stage reaction unit is used to defluorinate the liquid transferred from the mixing unit or the previous stage precipitation unit. Each stage precipitation unit is used to generate fluoride-containing precipitates, and the last stage precipitation unit is used to obtain the qualified discharge water after the fluoride-containing precipitates have settled.

[0021] Furthermore, the wastewater reduction module also includes: The third transfer unit is used to transfer the alkaline wastewater that has not passed through the pilot filtration membrane unit to the mixing unit after pre-filtration of the alkaline wastewater through the pilot filtration membrane unit, and to mix it with the second type of wastewater and / or the fluoride-containing concentrate, and / or to the designated reaction unit for defluorination reaction.

[0022] The present invention has at least the following beneficial effects: The proposed solution classifies wastewater into different categories based on pH value, enabling more precise treatment according to the characteristics of the wastewater, improving treatment efficiency, ensuring that the water separated from the wastewater meets higher recycling standards, and improving the separation efficiency of the membrane filtration system, reducing membrane fouling problems. By mixing the fluoride concentrate with the second type of wastewater and treating it through physicochemical precipitation, the fluoride ions in the two wastewater streams can be concentrated together. The fluoride precipitate produced by the precipitation reaction is easy to treat and dispose of, reducing the risk of water and soil pollution. Furthermore, the solution proposed in this invention can further improve the separation efficiency of fluoride ions in wastewater by introducing at least two stages of filtration membrane units. By filtering the wastewater multiple times through multiple layers of filtration membrane units, the concentration of fluoride ions can be significantly reduced, ensuring that the final filtered liquid meets the requirements of standard recycled water, improving the utilization efficiency of the filtration membrane system, avoiding excessive burden on a single filtration membrane unit, extending the service life of the filtration membrane, and reducing the replacement and maintenance costs of the filtration membrane. Based on this, the proposed solution of this invention mixes the fluoride-containing concentrate with the second type of wastewater through a physicochemical precipitation method. This allows for the defluorination reaction to be carried out through a multi-stage reaction unit and the separation of fluorides through a multi-stage precipitation unit, effectively reducing the concentration of fluoride in the wastewater. This ensures that the final water quality meets the discharge standards and that the generated precipitate is easy to treat, significantly reducing the environmental pollution risk of fluoride-containing wastewater discharge. In addition, this solution achieves precise pH control. By continuously monitoring the real-time pH value and adjusting it by regulating the liquid delivery rate, it can ensure that the first type of wastewater reaches the optimal pH value as much as possible, thereby improving the stability of water quality recovery.

[0023] Therefore, this invention proposes a method and system for discharging fluoride-containing wastewater. The proposed solution can more accurately treat different wastewaters according to their characteristics, which helps to improve treatment efficiency, reduces the burden on the filtration membrane system and sedimentation process, and greatly reduces the environmental impact of fluoride-containing wastewater by removing pollutants from it. This helps to reduce the risk of water and soil pollution, while also realizing the recycling and reuse of wastewater, reducing treatment costs and avoiding resource waste. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0025] Figure 1 This is a schematic diagram of the process flow for the fluoride-containing wastewater discharge method provided in Example 1; Figure 2 A schematic diagram of a method for adjusting the pH value of wastewater; Figures 3(a)-(e) are example flowcharts of optional processes for discharging fluoride-containing wastewater; Figure 4 This is a schematic diagram of the system architecture of the fluoride-containing wastewater discharge system provided in Example 2; Figure 5 This is a schematic diagram of the modular structure of a fluoride-containing wastewater discharge system.

[0026] Figure Labels 10 - Classification module; 20 - Wastewater reduction module; 21 - Catalysis unit; 22 - Separation unit; 23 - Concentration detection unit; 24 - First transfer unit; 25 - Control unit; 26 - Delay detection unit; 27 - Transport and regulation unit; 28 - Second transfer unit; 29 - Third transfer unit; 30 - Physicochemical precipitation module; 31 - Mixing unit; 32 - Reaction unit; 33 - Precipitation unit. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Various embodiments of the invention will be described more fully below. The invention may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of the invention to the specific embodiments disclosed herein, but rather the invention should be understood to cover all modifications, equivalents, and / or alternatives falling within the spirit and scope of the various embodiments of the invention.

[0029] In the following, the terms “comprising” or “may include” as used in various embodiments of the invention indicate the presence of the disclosed functions, operations, or elements, and do not limit the addition of one or more functions, operations, or elements. Furthermore, as used in various embodiments of the invention, the terms “comprising,” “having,” and their cognates are intended only to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing, and should not be construed as primarily excluding the presence of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing, or the possibility of adding one or more combinations of the foregoing.

[0030] In various embodiments of the invention, the expression "or" or "at least one of A and / or B" includes any combination or all combinations of the words listed simultaneously. For example, the expression "A or B" or "at least one of A and / or B" may include A, may include B, or may include both A and B.

[0031] The expressions used in the various embodiments of the present invention (such as "first," "second," etc.) may modify various constituent elements in the various embodiments, but do not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only used for the purpose of distinguishing one element from other elements. For example, a first user device and a second user device refer to different user devices, although both are user devices. For example, a first element may be referred to as a second element without departing from the scope of the various embodiments of the present invention, and similarly, a second element may also be referred to as a first element.

[0032] It should be noted that, in this invention, unless otherwise explicitly specified and defined, terms such as "installation," "connection," and "fixation" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0033] In this invention, those skilled in the art should understand that the terms indicating orientation or positional relationship in the text are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the purpose of facilitating the description of this invention and simplifying 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, and therefore should not be construed as a limitation of this invention.

[0034] The terminology used in the various embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to limit the various embodiments of the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the invention pertain. The terms (such as those defined in a generally used dictionary) are to be interpreted as having the same meaning as in the context of the relevant technical field and are not to be interpreted as having an idealized or overly formal meaning, unless clearly defined in the various embodiments of the invention.

[0035] Example 1 This embodiment proposes a method for discharging fluoride-containing wastewater. This method can separate usable water from the wastewater for recycling, while simultaneously reducing the amount of wastewater requiring physicochemical precipitation, thus saving resource costs. Please refer to [link to relevant documentation]. Figure 1 -Figure 3(e), the method includes: S100: Based on pH value, fluoride-containing wastewater is classified into Class I wastewater and / or Class II wastewater.

[0036] It should be noted that step S100 can test one group of fluoride-containing wastewater or multiple groups of fluoride-containing wastewater. When testing one group of fluoride-containing wastewater, the group of fluoride-containing wastewater can be classified into Class I wastewater or Class II wastewater based on the pH value. When testing multiple groups of fluoride-containing wastewater, each group of fluoride-containing wastewater can be classified into Class I wastewater and / or Class II wastewater based on the pH value.

[0037] In this embodiment, the first type of wastewater includes alkaline wastewater and acidic wastewater with a pH value not less than a first preset value, and the second type of wastewater includes acidic wastewater with a pH value less than the first preset value. In an optional embodiment, the first preset value is 2, and acidic wastewater with a pH value not less than 2 can be regarded as dilute acid wastewater, while acidic wastewater with a pH value less than 2 can be regarded as concentrated acid wastewater. That is, the first type of wastewater includes alkaline wastewater and acidic wastewater with a pH value not less than 2, and the second type of wastewater includes acidic wastewater with a pH value less than 2.

[0038] S200: Pre-treats Class I wastewater and adjusts its pH value. Using a filtration membrane system, the pH-adjusted Class I wastewater is separated into compliant recycled water and fluoride concentrate.

[0039] In this embodiment, the pretreatment of the first type of wastewater is achieved through a catalytic unit. The catalytic unit may include, but is not limited to, metal composite catalytic materials such as iron and manganese. The catalytic unit can degrade oxidizing substances such as hydrogen peroxide and ozone. The filtration membrane system includes at least two stages of filtration membrane units. The filtration membrane system is used to separate the first type of wastewater after pH adjustment into compliant recycled water and fluoride-containing concentrate, which may include: The first type of wastewater after pH adjustment is identified as the liquid to be filtered. The liquid to be filtered is separated into filtered liquid and fluoride concentrate by the current filtration membrane unit. The concentration of fluoride ions in the filtered liquid obtained from the separation is detected. If the concentration of fluoride ions in the filtered liquid is lower than the preset concentration threshold, the filtered liquid is determined to be qualified recycled water. If the fluoride ion concentration in the filtered liquid is not lower than the concentration threshold, the filtered liquid is redefined as the liquid to be filtered and passed to the next stage filtration membrane unit. The step of "separating the liquid to be filtered into the filtered liquid and the fluoride concentrate through the current filtration membrane unit" is executed again until the fluoride ion concentration in the filtered liquid is lower than the concentration threshold. Furthermore, the method proposed in this embodiment can also, when the concentration of fluoride ions in the currently separated filtered liquid is lower than the concentration threshold, re-determine the currently separated fluoride-containing concentrate as the liquid to be filtered and transfer it to the next-level filtration membrane unit, and execute the step of "separating the liquid to be filtered into filtered liquid and fluoride-containing concentrate through the current filtration membrane unit" again.

[0040] For example, please refer to Figure 3(a). When the filtration membrane system includes a first filtration membrane unit and a second filtration membrane unit, the liquid to be filtered can be passed through the first filtration membrane unit and the second filtration membrane unit in sequence, thereby separating the qualified recycled water from the first type of wastewater. The fluoride-containing concentrate obtained by separating through the first filtration membrane unit and the second filtration membrane unit can be mixed with the second type of wastewater in the subsequent step S300. Please refer to Figures 3(b)-3(d). When the filtration membrane system includes a first filtration membrane unit, a second filtration membrane unit, and a third filtration membrane unit, the screenshot shows the liquid to be filtered passing through the first filtration membrane unit, the second filtration membrane unit, and the third filtration membrane unit in sequence, thereby separating the first type of wastewater into qualified recycled water. The fluoride-containing concentrate separated by the first and second filtration membrane units can be mixed with the second type of wastewater in the subsequent step S300, while the fluoride-containing concentrate separated by the third filtration membrane unit can be re-identified as the liquid to be filtered and transferred to the second filtration membrane unit for filtration again.

[0041] S300: Fluorine concentrate is mixed with Class II wastewater to form mixed wastewater. The mixed wastewater is then separated into compliant discharge water and fluorine precipitates through physicochemical precipitation treatment.

[0042] In this embodiment, step S300 is implemented by a physicochemical precipitation treatment system, which includes a mixing unit, at least two reaction units and at least two precipitation units. The number of reaction units and precipitation units are the same and can be set according to the defluorination requirements. The primary reaction unit is connected to the mixing unit, each level of reaction unit is connected to the precipitation unit of the same level, and each level of reaction unit except the primary reaction unit is connected to the precipitation unit of the previous level. The mixing unit is used to mix the fluoride concentrate with the second type of wastewater. Any first-level reaction unit is used to defluorinate the liquid transferred from the mixing unit or the previous-level precipitation unit. Each precipitation unit is used to generate fluoride precipitates, and the last precipitation unit is used to obtain compliant discharge water after the fluoride precipitates have settled. The defluorination reactions carried out by each reaction unit can be different from each other, and the fluoride precipitates generated by each precipitation unit can be different from each other. In this embodiment, the reaction unit may include a reaction tank for carrying out the defluorination reaction, and the precipitation unit may include a precipitation tank for precipitating fluoride-containing precipitates. There is a corresponding relationship between the reaction tank and the precipitation tank of the same level. After the defluorination reaction such as calcium salt defluorination is completed in the reaction tank, the precipitation tank can separate various precipitates, including fluoride-containing precipitates, from the liquid, such as calcium fluoride precipitate, aluminum hydroxide precipitate, calcium sulfate precipitate, etc.

[0043] In one optional embodiment, the physicochemical precipitation treatment system includes a mixing unit, a primary reaction unit, a primary precipitation unit, a secondary reaction unit, and a secondary precipitation unit connected in sequence. After the precipitation of fluoride-containing precipitates is completed in the secondary precipitation unit, the remaining liquid is the compliant discharge water. Preferably, the method proposed in this embodiment can further reduce the fluoride ion concentration in the compliant discharge water by nanofiltration interception and fluoride removal resin adsorption. Therefore, mixed wastewater with a fluoride ion concentration higher than 2000 mg / L can have its fluoride ion concentration reduced to below 50 mg / L after two stages of reaction and sedimentation, including a primary reaction unit, a primary sedimentation unit, a secondary reaction unit, and a secondary sedimentation unit. After nanofiltration interception and fluoride removal resin adsorption treatment, the fluoride ion concentration in the liquid can be reduced to 1 mg / L or lower.

[0044] It should be noted that the qualified recycled water obtained in step S200 can be recycled back into the pure water system for reuse, while the qualified discharged water obtained in step S300 can be discharged into the discharge pool.

[0045] Please see again Figure 2 Preferably, the pH adjustment of the first type of wastewater in step S200 includes: S210: Continuously monitor the pH value of the first type of wastewater, generate a control signal for adding control liquid to the first type of wastewater based on the current monitoring results, and determine the current delay time by the length of the control liquid's transport path and the current transport flow rate of the control liquid.

[0046] S220: Repeatedly execute the steps of updating the control signal based on the current detection results and the current delay time and re-determining the current delay time to continuously update the delivery flow rate of the control liquid until the pH value of the first type of wastewater reaches the target value, and generate a stop signal to stop adding control liquid to the first type of wastewater.

[0047] In this embodiment, step S200 can adjust the pH value of the first type of wastewater by adding sodium hydroxide and other chemical solutions through a dosing pump. The pH value of the first type of wastewater can be detected by a pH sensor. After the pH value of the first type of wastewater is detected, the dosing pump starts to add chemicals. At this time, the delivery pipe of the dosing pump is filled with chemical solution. When the dosing pump is started, the chemical solution will immediately mix with the first type of wastewater. Since there is a certain delay between the time for mixing the first type of wastewater and the solution and the time for the pH sensor to detect the pH value, the method proposed in this embodiment can appropriately adjust the delivery speed of the solution through steps S210-S220, thereby improving the accuracy of adding the solution and ensuring that the pH value of the first type of wastewater can be adjusted as accurately as possible. In an optional embodiment, the function of adjusting the liquid delivery speed can be realized by a frequency converter.

[0048] Optionally, the pretreatment of the first type of wastewater and the adjustment of its pH value in step S200 may specifically include: The first type of wastewater is transferred to the catalytic unit for pretreatment, and the pH value of the pretreated first type of wastewater is adjusted by the pH control unit. The pilot filtration membrane unit in the filtration membrane system pre-filters alkaline wastewater with a pH value greater than a second preset value from the first type of wastewater. Acidic wastewater, alkaline wastewater with a pH value not greater than the second preset value, and / or alkaline wastewater passing through the pilot filtration membrane unit are then transferred to the catalytic unit for pretreatment. The pH value of the pretreated first type of wastewater is adjusted by the pH control unit. In this embodiment, the second preset value is 12. Alkaline wastewater with a pH value not greater than 12 can be considered as dilute alkaline wastewater, while alkaline wastewater with a pH value greater than 12 can be considered as concentrated alkaline wastewater. And / or, the alkaline wastewater in the first type of wastewater is pre-filtered through the pilot filtration membrane unit, the alkaline wastewater passing through the pilot filtration membrane unit is transferred to the catalytic unit for pretreatment, and the pH value of the pretreated alkaline wastewater and / or the acidic wastewater in the first type of wastewater is adjusted through the pH control unit. The pilot filter membrane unit is not included in the aforementioned at least two stages of filter membrane units. That is, the filter membrane system mentioned in this embodiment includes at least two stages of filter membrane units in addition to the pilot filter membrane unit. In this embodiment, the pilot filter membrane unit includes the fourth filter membrane unit shown in Figures 3(c)-3(e).

[0049] Furthermore, please refer again to Figure 3(e). The method proposed in this embodiment can also detect the currently separated fluoride concentrate through preset detection conditions. When the fluoride concentrate meets the detection conditions, the fluoride concentrate is reclassified as alkaline wastewater in the first type of wastewater, and the step of "pre-filtering alkaline wastewater in the first type of wastewater through the pilot filtration membrane unit" is executed. In an optional implementation, the preset detection conditions can be associated with values ​​such as pH value and pollutant concentration of the currently separated fluoride concentrate. For example, when the pollutant concentration of the currently separated fluoride concentrate meets the detection conditions, the currently separated fluoride concentrate can be reclassified as alkaline wastewater in the first category of wastewater, and the corresponding steps can be performed.

[0050] Furthermore, the method proposed in this embodiment can further pre-filter the alkaline wastewater through the pilot filtration membrane unit, and then transfer the alkaline wastewater that has not passed through the pilot filtration membrane unit to the mixing unit to mix with the second type of wastewater and / or fluoride-containing concentrate, and / or transfer it to the designated reaction unit for defluorination reaction; Preferably, the method proposed in this embodiment can also set detection conditions to detect alkaline wastewater that has not passed through the pilot filter membrane unit, and determine the target to be transferred by this part of the alkaline wastewater based on the detection results; For example, when the alkaline wastewater that has not passed through the pilot filtration membrane unit meets the first preset index, it can be directly added to the secondary reaction unit for secondary defluorination reaction. When the alkaline wastewater that has not passed through the pilot filtration membrane unit does not meet the first preset index but meets the second preset index, it can be added to the primary reaction unit for primary defluorination reaction. When the alkaline wastewater that has not passed through the pilot filtration membrane unit does not meet the first preset index and the second preset index, it is added to the mixing unit to mix with the first type of wastewater.

[0051] Example 2 Please see Figures 4-5 The present invention also proposes a fluoride-containing wastewater discharge system. The fluoride-containing wastewater discharge system proposed in this embodiment can be used to implement the fluoride-containing wastewater discharge method proposed in Embodiment 1. The system specifically includes: Classification module 10 is used to classify fluoride-containing wastewater into Class I wastewater and / or Class II wastewater based on pH value; Wastewater reduction module 20 includes a filtration membrane system for pretreating Class I wastewater and adjusting the pH value of Class I wastewater. The filtration membrane system separates the Class I wastewater after pH adjustment into compliant recycled water and fluoride concentrate. The physicochemical precipitation module 30 is used to mix the fluoride-containing concentrate with the second type of wastewater to form mixed wastewater, and then separate the mixed wastewater into compliant discharge water and fluoride-containing precipitates through physicochemical precipitation treatment.

[0052] In this embodiment, the first type of wastewater includes alkaline wastewater and acidic wastewater with a pH value not less than a first preset value, and the second type of wastewater includes acidic wastewater with a pH value less than the first preset value; in an optional embodiment, the first preset value is 2.

[0053] Specifically, the filtration membrane system includes at least two stages of filtration membrane units, and the wastewater reduction module 20 includes: Catalytic unit 21 is used for pretreatment of Class I wastewater; Separation unit 22 is used to identify the first type of wastewater after pH adjustment as the liquid to be filtered, and to separate the liquid to be filtered into filtered liquid and fluoride concentrate through the current filtration membrane unit. The concentration detection unit 23 is used to detect the concentration of fluoride ions in the currently separated filtered liquid. If the concentration of fluoride ions in the filtered liquid is lower than the preset concentration threshold, the filtered liquid is determined to be qualified recycled water. The first transfer unit 24 is used to re-determine the filtered liquid as the liquid to be filtered and transfer it to the next stage filtration membrane unit when the fluoride ion concentration in the filtered liquid is not lower than the concentration threshold, so that the separation unit 22 can perform the step of "separating the liquid to be filtered into the filtered liquid and the fluoride concentrate through the current filtration membrane unit" again until the fluoride ion concentration in the filtered liquid is lower than the concentration threshold. The first transfer unit 24 is also used to re-determine the fluoride-containing concentrate obtained from the current separation as the liquid to be filtered and transfer it to the next-level filtration membrane unit when the fluoride ion concentration in the currently separated filtered liquid is lower than the concentration threshold, so that the separation unit 22 can perform the step of "separating the liquid to be filtered into the filtered liquid and the fluoride-containing concentrate through the current filtration membrane unit" again.

[0054] Optionally, the wastewater reduction module 20 also includes: The control unit 25 is used to transfer the first type of wastewater to the catalytic unit 21 for pretreatment and to control the pH value of the pretreated first type of wastewater. The pilot filtration membrane unit in the filtration membrane system pre-filters alkaline wastewater with a pH value greater than the second preset value in the first type of wastewater. The acidic wastewater, alkaline wastewater with a pH value not greater than the second preset value, and / or alkaline wastewater passing through the pilot filtration membrane unit are transferred to the catalytic unit 21 for pretreatment, and the pH value of the first type of wastewater after pretreatment is adjusted. And / or, the alkaline wastewater in the first type of wastewater is pre-filtered through the pilot filtration membrane unit, and the alkaline wastewater passing through the pilot filtration membrane unit is transferred to the catalytic unit 21 for pretreatment, and the pH value of the pretreated alkaline wastewater and / or the acidic wastewater in the first type of wastewater is adjusted.

[0055] Preferably, the wastewater reduction module 20 further includes: The delay detection unit 26 is used to continuously detect the pH value of the first type of wastewater, generate a control signal for adding control liquid to the first type of wastewater based on the current detection result, and determine the current delay time by the length of the control liquid's transport path and the current transport flow rate of the control liquid. The delivery regulating unit 27 is used to cause the delay detection unit to repeatedly execute the steps of updating the regulation signal based on the current detection result and the current delay time and re-determining the current delay time, so as to continuously update the delivery flow rate of the regulating liquid until the pH value of the first type of wastewater reaches the target value, and then generate a stop signal to stop adding the regulating liquid to the first type of wastewater.

[0056] Furthermore, the wastewater reduction module 20 also includes: The second transfer unit 28 is used to detect the currently separated fluoride concentrate under preset detection conditions, and when the fluoride concentrate meets the detection conditions, it reclassifies the fluoride concentrate as alkaline wastewater in the first type of wastewater, and causes the control unit 25 to perform the step of "pre-filtering alkaline wastewater in the first type of wastewater through the pilot filtration membrane unit".

[0057] Specifically, the physicochemical precipitation module 30 includes a mixing unit 31, at least two-stage reaction units 32, and at least two-stage precipitation units 33; The mixing unit 31 is used to mix the fluoride concentrate and the second type of wastewater. The primary reaction unit is connected to the mixing unit, and each level of reaction unit is connected to the same level of sedimentation unit. Except for the primary reaction unit, each level of reaction unit is connected to the previous level of sedimentation unit. Any stage of the reaction unit is used to defluorinate the liquid transferred from the mixing unit or the previous stage of the precipitation unit. Each stage of the precipitation unit is used to generate fluoride-containing precipitates, and the last stage of the precipitation unit is used to obtain compliant discharge water after the fluoride-containing precipitates have settled.

[0058] Furthermore, the wastewater reduction module 20 also includes: The third transfer unit 29 is used to transfer the alkaline wastewater that has not passed through the pilot filtration membrane unit to the mixing unit 31 after pre-filtration of the alkaline wastewater through the pilot filtration membrane unit, to mix it with the second type of wastewater and / or fluoride-containing concentrate, and / or to the designated reaction unit 32 for defluorination reaction.

[0059] In summary, this invention proposes a method and system for discharging fluoride-containing wastewater. The proposed solution can more accurately treat different wastewaters based on their characteristics, which helps improve treatment efficiency, reduces the burden on the filtration membrane system and sedimentation process, and greatly reduces the environmental impact of fluoride-containing wastewater by removing pollutants. This helps reduce the risk of water and soil pollution, while also enabling wastewater recycling and reuse, reducing treatment costs, and avoiding resource waste.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for the discharge of fluorine-containing waste water, characterized in that, The method comprises: dividing fluorine-containing wastewater into first-type wastewater and / or second-type wastewater based on pH value; pretreating the first-type wastewater, regulating pH value of the first-type wastewater, and separating the first-type wastewater with regulated pH value into standard recovery water and fluorine-containing concentrated liquid by using a filtration membrane system; mixing the fluorine-containing concentrated liquid and the second-type wastewater into mixed wastewater, and separating the mixed wastewater into standard discharge water and fluorine-containing precipitate by using a physicochemical precipitation treatment method.

2. The fluorine-containing wastewater discharge method according to claim 1, characterized by, The filtration membrane system comprises at least two filtration membrane units, and separating the first-type wastewater with regulated pH value into standard recovery water and fluorine-containing concentrated liquid by using the filtration membrane system comprises: determining the first-type wastewater with regulated pH value as to-be-filtered liquid, separating the to-be-filtered liquid into filtered liquid and fluorine-containing concentrated liquid by using a current filtration membrane unit; detecting fluorine ion concentration in the filtered liquid obtained in the current separation, and determining the filtered liquid as standard recovery water if the fluorine ion concentration in the filtered liquid is lower than a preset concentration threshold value; if the fluorine ion concentration in the filtered liquid is not lower than the concentration threshold value, re-determining the filtered liquid as to-be-filtered liquid and delivering the to-be-filtered liquid to a next filtration membrane unit, and executing again the step of separating the to-be-filtered liquid into filtered liquid and fluorine-containing concentrated liquid by using a current filtration membrane unit until the fluorine ion concentration in the filtered liquid is lower than the concentration threshold value.

3. The fluorine-containing wastewater discharge method according to claim 2, characterized by, The method further comprises: if the fluorine ion concentration in the filtered liquid obtained in the current separation is lower than the concentration threshold value, re-determining the fluorine-containing concentrated liquid obtained in the current separation as to-be-filtered liquid and delivering the to-be-filtered liquid to a previous filtration membrane unit, and executing again the step of separating the to-be-filtered liquid into filtered liquid and fluorine-containing concentrated liquid by using a current filtration membrane unit.

4. The fluorine-containing wastewater discharge method according to claim 1, characterized by, The pretreatment of the first-type wastewater is realized by using a catalytic unit; the first-type wastewater comprises alkaline wastewater and acidic wastewater with pH value not less than a first preset value, and the second-type wastewater comprises acidic wastewater with pH value less than the first preset value.

5. The fluorine-containing wastewater discharge method according to claim 4, characterized by, The pretreatment of the first-type wastewater and the regulation of pH value of the first-type wastewater comprise: delivering the first-type wastewater to the catalytic unit for pretreatment, and regulating pH value of the first-type wastewater after pretreatment by using a pH regulating unit; pre-filtering alkaline wastewater with pH value greater than a second preset value in the first-type wastewater by using a pilot filtration membrane unit in the filtration membrane system, delivering acidic wastewater, alkaline wastewater with pH value not greater than the second preset value and / or alkaline wastewater passing through the pilot filtration membrane unit in the first-type wastewater to the catalytic unit for pretreatment, and regulating pH value of the first-type wastewater after pretreatment by using the pH regulating unit; And / or, the alkaline wastewater in the first type of wastewater is pre-filtered by the pilot filtration membrane unit, the alkaline wastewater passing through the pilot filtration membrane unit is delivered to the catalytic unit for pretreatment, and the pH value of the alkaline wastewater after pretreatment and / or the acidic wastewater in the first type of wastewater is adjusted by the pH adjustment unit.

6. The fluorine-containing wastewater discharge method according to claim 1, 4 or 5, characterized by, The method further comprises: The pH value of the first type of wastewater is continuously detected, and a control signal for adding a control liquid to the first type of wastewater is generated based on the current detection result; and the current delay time is determined by the length of the delivery path of the control liquid and the current delivery flow rate of the control liquid. The steps of updating the control signal based on the current detection result and the current delay time and re-determining the current delay time are repeatedly performed to continuously update the delivery flow rate of the control liquid until the pH value of the first type of wastewater reaches a target value, and a stop signal for stopping the addition of the control liquid to the first type of wastewater is generated.

7. The fluorine-containing wastewater discharge method according to claim 5, characterized by, The method further comprises: The fluorine-containing concentrated liquid obtained by separation is detected under a preset detection condition; If the fluorine-containing concentrated liquid meets the detection condition, the fluorine-containing concentrated liquid is re-determined as the alkaline wastewater in the first type of wastewater, and the step of pre-filtering the alkaline wastewater in the first type of wastewater by the pilot filtration membrane unit is performed.

8. The fluorine-containing wastewater discharge method according to claim 5 or 7, characterized by, The mixed wastewater is separated into the standard recovery water and the fluorine-containing precipitate by the physicochemical precipitation treatment method, which is achieved by at least two stages of reaction units and at least two stages of precipitation units; The first-stage reaction unit is connected with a mixing unit for mixing the fluorine-containing concentrated liquid and the second type of wastewater, each stage of reaction unit is connected with the same stage of precipitation unit, and each stage of reaction unit except the first-stage reaction unit is connected with the precipitation unit of the previous stage. Any stage of reaction unit is used for defluorination reaction of the liquid delivered from the mixing unit or the precipitation unit of the previous stage, each stage of precipitation unit is used for generating the fluorine-containing precipitate, and the last-stage precipitation unit is used for obtaining the standard discharge water after the precipitation of the fluorine-containing precipitate.

9. The fluorine-containing wastewater discharge method according to claim 8, characterized by, The method further comprises: After the alkaline wastewater is pre-filtered by the pilot filtration membrane unit, the alkaline wastewater not passing through the pilot filtration membrane unit is delivered to the mixing unit to be mixed with the second type of wastewater and / or the fluorine-containing concentrated liquid, and / or is delivered to a designated reaction unit for defluorination reaction.

10. A fluorine-containing wastewater discharge system characterized by comprising: The system comprises: A classification module is configured to divide the fluorine-containing wastewater into the first type of wastewater and / or the second type of wastewater based on the pH value; A wastewater reduction module comprises a filtration membrane system configured to pretreat the first type of wastewater, adjust the pH value of the first type of wastewater, and separate the first type of wastewater after the pH value is adjusted into the standard recovery water and the fluorine-containing concentrated liquid by using the filtration membrane system; A physicochemical precipitation module is configured to mix the fluorine-containing concentrated liquid with the second type of wastewater into the mixed wastewater, and separate the mixed wastewater into the standard discharge water and the fluorine-containing precipitate by using the physicochemical precipitation treatment method.

11. The fluorochemical wastewater discharge system of claim 10, wherein, The filtration membrane system comprises at least two filtration membrane units, and the wastewater reduction module comprises: a separation unit configured to separate the first type of wastewater after the pH value is regulated into a filtrate and a fluorine-containing concentrate by using a current filtration membrane unit, and determine the filtrate as a to-be-filtered liquid; a concentration detection unit configured to detect a fluorine ion concentration in the filtrate obtained by the current separation, and determine the filtrate as standard recovery water if the fluorine ion concentration in the filtrate is lower than a preset concentration threshold value; a first transmission unit configured to, when the fluorine ion concentration in the filtrate is not lower than the concentration threshold value, re-determine the filtrate as the to-be-filtered liquid and transmit the to-be-filtered liquid to a next filtration membrane unit, so that the separation unit performs again the step of separating the to-be-filtered liquid into the filtrate and the fluorine-containing concentrate by using the current filtration membrane unit, until the fluorine ion concentration in the filtrate is lower than the concentration threshold value; the first transmission unit is further configured to, when the fluorine ion concentration in the filtrate obtained by the current separation is lower than the concentration threshold value, re-determine the fluorine-containing concentrate obtained by the current separation as the to-be-filtered liquid and transmit the to-be-filtered liquid to a previous filtration membrane unit, so that the separation unit performs again the step of separating the to-be-filtered liquid into the filtrate and the fluorine-containing concentrate by using the current filtration membrane unit.

12. The fluorochemical wastewater discharge system of claim 10, wherein, The wastewater reduction module further comprises: a catalysis unit configured to pretreat the first type of wastewater; the first type of wastewater comprises alkaline wastewater and acidic wastewater with a pH value not less than a first preset value, and the second type of wastewater comprises acidic wastewater with a pH value less than the first preset value.

13. The fluorochemical wastewater discharge system of claim 12, wherein, The wastewater reduction module further comprises: a regulation unit configured to transmit the first type of wastewater to the catalysis unit for pretreatment, and regulate a pH value of the first type of wastewater after the pretreatment; pretreat alkaline wastewater with a pH value greater than a second preset value in the first type of wastewater by using a pilot filtration membrane unit in the filtration membrane system, transmit acidic wastewater in the first type of wastewater, alkaline wastewater with a pH value not greater than the second preset value and / or alkaline wastewater passing through the pilot filtration membrane unit to the catalysis unit for pretreatment, and regulate a pH value of the first type of wastewater after the pretreatment; and / or, pretreat alkaline wastewater in the first type of wastewater by using the pilot filtration membrane unit, transmit alkaline wastewater passing through the pilot filtration membrane unit to the catalysis unit for pretreatment, and regulate a pH value of the alkaline wastewater after the pretreatment and / or acidic wastewater in the first type of wastewater.

14. The fluorochemical wastewater discharge system of claim 10, 12, or 13, wherein, The wastewater reduction module further comprises: a delay detection unit configured to continuously detect a pH value of the first type of wastewater, generate a regulation signal for adding a regulation liquid to the first type of wastewater based on a current detection result, and determine a current delay time by using a conveying path length of the regulation liquid and a current conveying flow rate of the regulation liquid. The delivery adjustment unit is configured to repeatedly perform the steps of updating the control signal based on the current detection result and the current delay time and re-determining the current delay time by the delay detection unit, so as to continuously update the delivery flow rate of the control liquid until a stop signal for stopping adding the control liquid to the first type of wastewater is generated when the pH value of the first type of wastewater reaches the target value.

15. The fluorochemical wastewater discharge system of claim 13, wherein, The wastewater reduction module further comprises: The second transmission unit is configured to detect the fluorine-containing concentrated liquid obtained by the current separation by a preset detection condition, and when the fluorine-containing concentrated liquid meets the detection condition, re-determine the fluorine-containing concentrated liquid as the alkaline wastewater in the first type of wastewater, and make the control unit perform the step of "pre-filtering the alkaline wastewater in the first type of wastewater by the pilot filtration membrane unit".

16. The fluorochemical wastewater discharge system of claim 13 or 15, wherein, The physicochemical precipitation module comprises a mixing unit, at least two reaction units and at least two precipitation units; The mixing unit is configured to mix the fluorine-containing concentrated liquid and the second type of wastewater, the first reaction unit is connected with the mixing unit, each reaction unit is connected with the same stage precipitation unit, and each reaction unit except the first reaction unit is connected with the precipitation unit of the previous stage; Any reaction unit is configured to perform defluorination reaction on the liquid transmitted from the mixing unit or the precipitation unit of the previous stage, each precipitation unit is configured to generate fluorine-containing precipitate, and the last stage precipitation unit is configured to obtain the discharge water meeting the standard after completing the precipitation of the fluorine-containing precipitate.

17. The fluorochemical wastewater discharge system of claim 16, wherein, The wastewater reduction module further comprises: The third transmission unit is configured to mix the alkaline wastewater which does not pass through the pilot filtration membrane unit with the second type of wastewater and / or the fluorine-containing concentrated liquid in the mixing unit after pre-filtering the alkaline wastewater by the pilot filtration membrane unit, and / or transmit the alkaline wastewater which does not pass through the pilot filtration membrane unit to a designated reaction unit for defluorination reaction.

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