PCB waste liquid heavy metal treatment method based on high-concentration waste liquid pretreatment device

Abstract

The disclosure provides a PCB waste liquid heavy metal treatment method based on a high-concentration waste liquid pretreatment device. The method comprises the following steps: acquiring a waste liquid stirring state parameter in a stirred tank; performing waste liquid stirring difference processing on the waste liquid stirring state parameter and a preset stirring state parameter to obtain a waste liquid stirring difference component; and sending a sludge discharge start-stop signal to a waste liquid pretreatment controller according to the waste liquid stirring difference component. After the waste liquid stirring state parameter in the tank is collected, the stirring condition of the current heavy metal waste liquid in the tank is determined, then the waste liquid stirring state parameter in the tank is compared with a standard waste liquid stirring state parameter, and finally, according to the difference value, the working mode of the sludge discharge valve on the stirred tank is adjusted by the waste liquid pretreatment controller, so that the heavy metal sludge formed after stirring in the waste liquid can be quickly discharged, and the treatment cost of the PCB waste liquid is effectively reduced.

Description

Technical Field

[0001] This disclosure relates to the field of PCB manufacturing technology, and in particular to a method for treating heavy metals in PCB waste liquid based on a high-concentration waste liquid pretreatment device. Background Technology

[0002] The copper-containing wastewater from circuit board factories mainly consists of complexed copper, with some free copper also present. Free metal ions in the water can be removed by adjusting the alkali content to achieve a co-precipitation value or by using polymeric coagulants such as polyferric sulfate and polyaluminum chloride for enhanced coagulation. However, the complexed copper in the water is highly stable and difficult to remove using these methods; therefore, it requires prior treatment to break down the complexes.

[0003] Copper complexation wastewater to remove divalent copper ions (Cu) 2+ Besides copper ions, a large amount of complexed copper is also present. There are three main types of complexes formed between copper ions and circuit board wastewater: copper ammonia complex [Cu(NH3)4]. 2+ Copper chloride complex [Cu(Cl-)4] 2+ [and copper EDTA complex Cu(EDTA)] 2+ Some circuit board manufacturers classify complexed wastewater into ammonia-copper wastewater (the main pollutant is copper-ammonia complex [Cu(NH3)4]). 2+ And copper leaching wastewater (the main pollutant is copper EDTA complex [Cu(EDTA)]) 2+ For the copper-ammonia complex [Cu(NH3)4] 2+ Copper chloride complex [Cu(Cl-)4] 2+ Copper-EDTA complex [Cu(EDTA)] 2+ Under acidic conditions, ferrous sulfate is used as a complex-breaking agent. The mechanism is that the Fe2+ generated after the dissolution of ferrous sulfate can reduce the divalent copper ions in the complexed copper to monovalent copper ions. The complexes formed by monovalent copper ions with ammonia, EDTA and chloride ions are no longer stable. Monovalent copper ions easily react with hydroxide ions in water to form cuprous hydroxide precipitate.

[0004] Physicochemical precipitation for copper removal: For Cu-containing wastewater containing complexing agents, the first consideration should be the self-reaction of hydrogen peroxide in the wastewater to break down the complex, followed by chemical precipitation.

[0005] The principle of the complex-breaking reaction sodium sulfide (Na2S) method is as follows:

[0006] Na₂S + Cu[M] → CuS↓ + Na₂[M]

[0007] Sodium sulfide is added to wastewater containing copper complexes, followed by sodium hydroxide to control the pH of the wastewater between 9 and 10. Then, an appropriate amount of polyacrylamide (PAM) is added to form a sparingly soluble precipitate, copper sulfide (CuS), with a very low solubility product. The copper ions are removed from the wastewater by the action of PAM. The sulfide precipitation method can reduce the copper content in wastewater containing copper complexes to below 0.5 mg / L. At pH 9-10, sulfide ions in sodium sulfide can form stable compounds with divalent copper ions, with a stability constant higher than that of divalent copper. These compounds are also displaced by ammonia, EDTA, chloride ions, etc., forming a black copper sulfide precipitate. However, CuS tends to form colloidal solutions (permeable to filter paper), requiring the addition of flocculants to form large flocs that settle together. This method is used to treat PCB complexed wastewater.

[0008] Often, poor sedimentation in sedimentation tanks prevents effluent from consistently meeting standards. Furthermore, the lack of online sulfide monitoring instruments necessitates excessive addition of Na2S in engineering projects. Excessive S2- causes foul odors in the wastewater, requiring the addition of ferrous salts to precipitate it, otherwise secondary pollution may occur.

[0009] Ferrous sulfate method: Because the stability constant of EDTA-Cu is smaller than that of EDTA-Fe under acidic conditions. 3+ The stability constants (pH=4, logarithm of the stability constant of EDTA-Cu lgKst = 10.2, EDTA-Fe) 3+ The logarithm of the stability constant lgKst = 14.7, therefore, adding Fe to the PCB complexing wastewater... 3+ Cu 2+ The process involves displacement, specifically converting complexed copper ions into free copper ions, and then adjusting the pH of the wastewater to remove Cu ions. 2+ It completely precipitates. In actual engineering, ferrous sulfate is added. Under acidic conditions, some of the Fe is precipitated through mechanical or air stirring. 2+ Oxidized to Fe 3+ (Some sources suggest that during this process, divalent copper ions are reduced to monovalent cuprous ions. The complexes formed by monovalent copper ions with ammonia, EDTA, and chloride ions become unstable, and monovalent copper ions readily react with hydroxide ions in water to form cuprous hydroxide precipitate.) Through Fe... 3+ Displace Cu from EDTA-Cu 2+ Then, NaOH is added to adjust the pH to around 9, generating Cu(OH)₂, Fe(OH)₃, and Fe(OH)₂ precipitates. The Fe(OH)₃ flocs are larger and have stronger adsorption properties, resulting in faster sedimentation and thus accelerating copper removal. This method has many successful engineering applications, with total copper levels in the effluent generally below 0.5 mg / L. However, it also has drawbacks: the dosage is relatively large, and it produces a significant amount of sludge.

[0010] Oxidation method: Adding a strong oxidant to the wastewater to oxidize the coordinating ions of copper, causing Cu... 2+ The precipitate is released and then precipitated with alkali. Commonly used oxidants include NaClO and Fenton's reagent. The Fenton's reagent oxidation method was used to treat EDTA-Cu-containing wastewater discharged from a circuit board copper plating workshop. The optimal reaction conditions were: pH around 3, reaction time 1 hour, H₂O₂ / COD = 2.0, and FeSO₄ dosage 10 g / L, achieving the goal of removing complexed copper ions and reducing COD. The oxidation-complex-breaking method can not only remove Cu... 2+ The sedimentation process reduces COD and NH3-N in wastewater, which is simple and easy to implement, but requires a relatively large dosage of oxidants, resulting in higher reagent costs. Summary of the Invention

[0011] The purpose of this disclosure is to overcome the shortcomings of the prior art and provide a method for treating heavy metals in PCB waste liquid based on a high-concentration waste liquid pretreatment device that effectively reduces costs.

[0012] The purpose of this disclosure is achieved through the following technical solution:

[0013] A method for treating heavy metals in PCB wastewater based on a high-concentration wastewater pretreatment device is disclosed. The high-concentration wastewater pretreatment device precipitates and removes heavy metals from the PCB wastewater. The high-concentration wastewater pretreatment device includes: a stirred tank, a pH probe, a stirring assembly, and a sludge discharge valve. The stirred tank is used to contain the PCB wastewater. The pH probe is mounted on the stirred tank and is used to collect pH data. The stirring assembly includes a stirring motor and a stirring paddle. The shaft of the stirring motor is connected to the stirring paddle, which is located inside the stirred tank and is used to stir the PCB wastewater to form heavy metal sludge at the bottom of the stirred tank. The sludge discharge valve is connected to the bottom sludge discharge port of the stirred tank to discharge the heavy metal sludge from the stirred tank.

[0014] The method for treating heavy metals in PCB waste liquid includes:

[0015] Obtain the stirring state parameters of the waste liquid inside the stirred tank;

[0016] The stirring state parameters of the waste liquid in the reactor are compared with the preset stirring state parameters to obtain the waste liquid stirring state difference.

[0017] The waste liquid agitation differential is used to send a sludge discharge start / stop signal to the waste liquid pretreatment controller to adjust the working mode of the sludge discharge valve.

[0018] In one embodiment, obtaining the stirring state parameters of the waste liquid inside the stirred tank includes: obtaining the stirring acid-base value of the waste liquid inside the stirred tank.

[0019] In one embodiment, the step of performing waste liquid stirring state parameter and preset stirring state parameter waste liquid stirring state difference processing to obtain waste liquid stirring state difference includes: calculating the difference between the stirring acid-base value of the waste liquid in the vessel and the preset waste liquid acid-base value to obtain waste liquid stirring state acid-base difference.

[0020] In one embodiment, the step of sending a sludge discharge start / stop signal to the waste liquid pretreatment controller based on the waste liquid agitation difference to adjust the working mode of the sludge discharge valve includes: detecting whether the waste liquid agitation acid-base difference is greater than or equal to a preset acid-base difference; and when the waste liquid agitation acid-base difference is greater than or equal to the preset acid-base difference, sending a sludge discharge start signal to the waste liquid pretreatment controller.

[0021] In one embodiment, the step of detecting whether the acid-base difference of the stirred waste liquid is greater than or equal to a preset acid-base difference further includes: when the acid-base difference of the stirred waste liquid is less than the preset acid-base difference, sending a sludge discharge shutdown signal to the waste liquid pretreatment controller.

[0022] In one embodiment, obtaining the stirring state parameters of the waste liquid inside the stirred tank includes: obtaining the supernatant level of the waste liquid inside the stirred tank.

[0023] In one embodiment, the step of performing waste liquid agitation difference processing on the agitation state parameters of the waste liquid in the vessel and the preset agitation state parameters to obtain the waste liquid agitation difference includes: calculating the difference between the supernatant level of the waste liquid in the vessel and the preset supernatant level of the waste liquid to obtain the waste liquid agitation supernatant level difference.

[0024] In one embodiment, the step of sending a sludge discharge start / stop signal to the waste liquid pretreatment controller based on the waste liquid agitation difference to adjust the working mode of the sludge discharge valve includes: detecting whether the waste liquid agitation supernatant level difference is greater than or equal to a preset supernatant level difference; and when the waste liquid agitation supernatant level difference is greater than or equal to the preset supernatant level difference, sending a sludge discharge start signal to the waste liquid pretreatment controller.

[0025] In one embodiment, the step of detecting whether the waste liquid agitated supernatant level difference is greater than or equal to a preset supernatant level difference further includes: when the waste liquid agitated supernatant level difference is less than the preset supernatant level difference, sending a sludge discharge shutdown signal to the waste liquid pretreatment controller.

[0026] In one embodiment, the step of obtaining the stirring state parameters of the waste liquid inside the stirred tank further includes: performing a neutralization operation on the waste liquid inside the stirred tank.

[0027] Compared with the prior art, this disclosure has at least the following advantages:

[0028] After collecting the stirring state parameters of the waste liquid inside the reactor, the current stirring state of the heavy metal waste liquid inside the reactor is determined. Then, the stirring state parameters of the waste liquid inside the reactor are compared with the standard waste liquid stirring state parameters to determine the difference between the current waste liquid treatment state and the standard waste liquid treatment state. Finally, based on the above difference value, the working mode of the sludge discharge valve on the reactor is adjusted through the waste liquid pretreatment controller to facilitate the rapid discharge of the precipitated sludge formed by the heavy metals in the waste liquid after stirring, effectively reducing the treatment cost of PCB waste liquid. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this disclosure and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart of a method for treating heavy metals in PCB waste liquid based on a high-concentration waste liquid pretreatment device in one embodiment;

[0031] Figure 2 This is a schematic diagram of a high-concentration waste liquid pretreatment device in one embodiment. Detailed Implementation

[0032] To facilitate understanding of this disclosure, a more complete description will be given below with reference to the accompanying drawings, which illustrate preferred embodiments of the present disclosure. However, this disclosure can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure.

[0033] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0035] This disclosure relates to a method for treating heavy metals in PCB wastewater based on a high-concentration wastewater pretreatment device. In one embodiment, the method includes acquiring stirring state parameters of the wastewater inside a stirred tank; performing wastewater stirring state parameter differential processing with preset stirring state parameters to obtain a wastewater stirring state difference component; and sending a sludge discharge start / stop signal to a wastewater pretreatment controller based on the wastewater stirring state difference component to adjust the working mode of the sludge discharge valve. After acquiring the stirring state parameters of the wastewater inside the tank, the current stirring condition of the heavy metal wastewater inside the stirred tank is determined. Then, the stirring state parameters of the wastewater inside the tank are compared with standard wastewater stirring state parameters to determine the difference between the current wastewater treatment condition and the standard wastewater treatment condition. Finally, based on the difference value, the working mode of the sludge discharge valve on the stirred tank is adjusted by the wastewater pretreatment controller to facilitate the rapid discharge of precipitated sludge formed after stirring of heavy metals in the wastewater, effectively reducing the treatment cost of PCB wastewater.

[0036] Please see Figure 1 This is a flowchart illustrating a method for treating heavy metals in PCB wastewater based on a high-concentration wastewater pretreatment device, according to an embodiment of this disclosure. Please refer to it as well. Figure 2 The high-concentration waste liquid pretreatment device 10 includes: a stirred tank 100, a pH probe 200, a stirring assembly 300, and a sludge discharge valve 400; the stirred tank 100 is used to contain PCB waste liquid; the pH probe 200 is disposed on the stirred tank 100 and is used to collect pH data from the stirred tank 100; the stirring assembly 300 includes a stirring motor 310 and a stirring paddle 320, the shaft of the stirring motor 310 is connected to the stirring paddle 320, the stirring paddle 320 is located inside the stirred tank 100, and the stirring paddle 320 is used to stir the PCB waste liquid to form heavy metal sludge at the bottom of the stirred tank 100; the sludge discharge valve 400 is connected to the bottom sludge discharge port of the stirred tank 100 to discharge the heavy metal sludge inside the stirred tank 100. The method for treating heavy metals in PCB waste liquid based on the high-concentration waste liquid pretreatment device includes some or all of the following steps.

[0037] S100: Obtain the stirring status parameters of the waste liquid inside the stirred tank 100.

[0038] In this embodiment, the stirring state parameter of the waste liquid inside the vessel refers to the current stirring status of the heavy metal waste liquid inside the stirred vessel 100. That is, the stirring state parameter represents the reaction state of the waste liquid within the stirred vessel 100 during the stirring process. By collecting the stirring state parameter, it is easy to determine the current stirring reaction and treatment status of the waste liquid inside the stirred vessel 100. The current heavy metal waste liquid inside the stirred vessel 100 is a high-concentration waste liquid, for example, the concentration of copper ions in the high-concentration waste liquid is 120 g / L to 180 g / L.

[0039] S200: Perform waste liquid stirring state parameters and preset stirring state parameters on waste liquid stirring state parameters to obtain waste liquid stirring state difference.

[0040] In this embodiment, the stirring state parameter of the waste liquid inside the vessel refers to the current stirring condition of the heavy metal waste liquid inside the stirred vessel 100, that is, the reaction state of the waste liquid inside the stirred vessel 100 during the stirring process. By collecting the stirring state parameter of the waste liquid inside the vessel, it is easy to determine the current stirring reaction of the waste liquid inside the stirred vessel 100 for treatment. The preset stirring state parameter is the reference stirring condition of the heavy metal waste liquid inside the stirred vessel 100, that is, the preset stirring state parameter is the standard reaction state of the waste liquid inside the stirred vessel 100 during the stirring process. By performing differential processing on the stirring state parameter of the waste liquid inside the vessel and the preset stirring state parameter, it is easy to determine the degree of difference in the reaction state of the waste liquid inside the stirred vessel 100 during the stirring process.

[0041] S300: Send a sludge discharge start / stop signal to the waste liquid pretreatment controller according to the waste liquid agitation differential to adjust the working mode of the sludge discharge valve 400.

[0042] In this embodiment, the waste liquid agitation difference is obtained based on the waste liquid agitation state parameters in the vessel and the preset agitation state parameters. The waste liquid agitation state parameters in the vessel represent the current agitation status of the heavy metal waste liquid in the agitated vessel 100, i.e., the reaction state of the waste liquid in the agitated vessel 100 during the agitation process. By collecting the waste liquid agitation state parameters in the vessel, it is easy to determine the current agitation reaction of the waste liquid in the agitated vessel 100 for treatment. The preset agitation state parameters represent the reference agitation status of the heavy metal waste liquid in the agitated vessel 100, i.e., the standard reaction state of the waste liquid in the agitated vessel 100 during the agitation process. By processing the waste liquid agitation difference between the waste liquid agitation state parameters in the vessel and the preset agitation state parameters, it is easy to determine the degree of difference in the reaction state of the waste liquid in the agitated vessel 100 during the agitation process. After obtaining the waste liquid stirring difference, it is easy to determine whether the current reaction of the waste liquid in the stirring vessel 100 is completed during the stirring process, thereby making it easy to determine whether the heavy metals in the waste liquid in the stirring vessel 100 have completely precipitated, and thus making it easy to remove the heavy metals in the waste liquid by controlling the opening and closing state of the sludge discharge valve 400.

[0043] In the above embodiment, after collecting the stirring state parameters of the waste liquid in the reactor, the current stirring state of the heavy metal waste liquid in the reactor is determined. Then, the stirring state parameters of the waste liquid in the reactor are compared with the standard waste liquid stirring state parameters to determine the difference between the current waste liquid treatment state and the standard waste liquid treatment state. Finally, based on the above difference value, the working mode of the sludge discharge valve on the reactor is adjusted by the waste liquid pretreatment controller to facilitate the rapid discharge of the precipitated sludge formed by the heavy metals in the waste liquid after stirring, effectively reducing the treatment cost of PCB waste liquid.

[0044] In one embodiment, obtaining the stirring state parameters of the waste liquid inside the stirred tank 100 includes: obtaining the pH value of the waste liquid inside the stirred tank 100. In this embodiment, the stirring state parameters of the waste liquid inside the tank refer to the current stirring status of the heavy metal waste liquid inside the stirred tank 100, that is, the stirring state parameters of the waste liquid inside the tank are the reaction status of the waste liquid in the stirred tank 100 during the stirring process. By collecting the stirring state parameters of the waste liquid inside the tank, it is convenient to determine the current stirring reaction and treatment status of the waste liquid in the stirred tank 100. The stirring state parameters of the waste liquid inside the tank include the pH value of the waste liquid inside the stirred tank 100, which is the pH value of the waste liquid inside the stirred tank 100 after the stirring operation. Specifically, the pH value of the waste liquid inside the tank is collected by a pH probe 200. By collecting the acid-base value of the waste liquid in the vessel during stirring, it is easy to determine the real-time liquid acid-base properties of the waste liquid in the stirred vessel 100 during the stirring process, thereby making it easier to determine the degree of heavy metal ion precipitation in the waste liquid in the stirred vessel 100.

[0045] Further, the step of performing waste liquid agitation difference processing on the waste liquid agitation state parameters and preset agitation state parameters to obtain waste liquid agitation difference includes: calculating the difference between the agitation pH of the waste liquid in the reactor and the preset agitation pH to obtain the waste liquid agitation pH difference. In this embodiment, the waste liquid agitation state parameters are the current agitation status of the heavy metal waste liquid in the agitated reactor 100, that is, the waste liquid agitation state parameters are the reaction status of the waste liquid in the agitated reactor 100 during the agitation process. By collecting the waste liquid agitation state parameters, it is convenient to determine the current agitation reaction of the waste liquid in the agitated reactor 100 for processing. The preset agitation state parameters are the reference agitation status of the heavy metal waste liquid in the agitated reactor 100, that is, the preset agitation state parameters are the standard reaction status of the waste liquid in the agitated reactor 100 during the agitation process. By performing differential processing on the stirring state parameters of the waste liquid inside the vessel and the preset stirring state parameters, the degree of difference in the reaction state of the waste liquid in the stirred vessel 100 during the stirring process can be easily determined. The stirring state parameters of the waste liquid inside the vessel include the acid-base value of the waste liquid inside the stirred vessel 100, which is the pH of the waste liquid inside the stirred vessel 100 after the stirring operation. By collecting the acid-base value of the waste liquid inside the vessel, the real-time liquid acidity and alkalinity of the waste liquid inside the stirred vessel 100 during the stirring process can be easily determined, thereby facilitating the determination of the degree of heavy metal ion precipitation in the waste liquid inside the stirred vessel 100. By calculating the difference between the acid-base value of the waste liquid inside the vessel and the preset acid-base value, the completeness of the removal of heavy metal ions by the waste liquid inside the stirred vessel 100 through chemical reaction can be easily determined.

[0046] Furthermore, the step of sending a sludge discharge start / stop signal to the waste liquid pretreatment controller based on the waste liquid agitation difference component to adjust the working mode of the sludge discharge valve 400 includes: detecting whether the waste liquid agitation acid-base difference is greater than or equal to a preset acid-base difference; and when the waste liquid agitation acid-base difference is greater than or equal to the preset acid-base difference, sending a sludge discharge start signal to the waste liquid pretreatment controller. In this embodiment, the waste liquid agitation difference component is obtained based on the waste liquid agitation state parameters in the vessel and the preset agitation state parameters. The waste liquid agitation state parameters in the vessel refer to the current agitation status of the heavy metal waste liquid in the agitated vessel 100, that is, the waste liquid agitation state parameters in the vessel refer to the reaction status of the waste liquid in the agitated vessel 100 during the agitation process. By collecting the waste liquid agitation state parameters in the vessel, it is convenient to determine the current agitation reaction status of the waste liquid in the agitated vessel 100 for treatment. The preset stirring state parameters are reference stirring conditions for the heavy metal waste liquid inside the stirred tank 100, i.e., the preset stirring state parameters are the standard reaction state of the waste liquid inside the stirred tank 100 during the stirring process. By processing the waste liquid stirring state difference between the stirred state parameters and the preset stirring state parameters, it is easy to determine the degree of difference in the reaction state of the waste liquid inside the stirred tank 100 during the stirring process. After obtaining the waste liquid stirring state difference, it is easy to determine whether the current reaction of the waste liquid inside the stirred tank 100 during the stirring process is complete, thereby facilitating the determination of whether the heavy metals in the waste liquid inside the stirred tank 100 have completely precipitated, and thus facilitating the removal of heavy metals from the waste liquid by controlling the opening and closing state of the sludge discharge valve 400. The stirred state parameters of the waste liquid inside the tank include the stirring pH value of the waste liquid inside the stirred tank 100, which is the pH value of the waste liquid inside the stirred tank 100 after the stirring operation. By collecting the pH value of the waste liquid during stirring, the real-time acidity or alkalinity of the waste liquid in the stirred tank 100 can be determined, thereby facilitating the determination of the degree of heavy metal ion precipitation in the waste liquid. By calculating the difference between the pH value of the waste liquid during stirring and the preset pH value, the completeness of heavy metal ion removal through chemical reaction in the waste liquid in the stirred tank 100 can be determined. If the pH difference during stirring is greater than or equal to the preset pH difference, it indicates that the pH of the waste liquid in the stirred tank 100 reaches neutral or alkaline after stirring, meaning that the heavy metal ions in the waste liquid in the stirred tank 100 have formed a poorly soluble precipitate after stirring. At this point, a sludge discharge start signal is sent to the waste liquid pretreatment controller to facilitate the discharge of the heavy metal ion precipitate formed in the waste liquid in the stirred tank 100.

[0047] In another embodiment, after detecting whether the acid-base difference of the stirred waste liquid is greater than or equal to a preset acid-base difference, the method further includes: when the acid-base difference of the stirred waste liquid is less than the preset acid-base difference, sending a sludge discharge shutdown signal to the waste liquid pretreatment controller. In this embodiment, the acid-base difference of the stirred waste liquid being less than the preset acid-base difference indicates that the acidity of the waste liquid in the stirred tank 100 is still acidic after stirring, which means that the heavy metal ions in the waste liquid in the stirred tank 100 have not yet precipitated after stirring. At this time, sending a sludge discharge shutdown signal to the waste liquid pretreatment controller avoids discharging the waste liquid in the stirred tank 100 that has not yet been cleared of heavy metal ions.

[0048] In another embodiment, the process of obtaining the stirring state parameters of the waste liquid inside the stirred tank 100 further includes: neutralizing the waste liquid inside the stirred tank 100. Specifically, lime is injected into the stirred tank 100 to neutralize the pH of the waste liquid, so that the waste liquid inside the stirred tank 100 reaches a pH level conducive to the formation of heavy metal precipitates.

[0049] In one embodiment, obtaining the stirring state parameters of the waste liquid inside the stirred tank 100 includes: obtaining the supernatant level of the waste liquid inside the stirred tank 100. In this embodiment, the stirring state parameters of the waste liquid inside the tank refer to the current stirring status of the heavy metal waste liquid inside the stirred tank 100, that is, the stirring state parameters of the waste liquid inside the tank refer to the reaction status of the waste liquid in the stirred tank 100 during the stirring process. By collecting the stirring state parameters of the waste liquid inside the tank, it is convenient to determine the current stirring reaction and treatment status of the waste liquid in the stirred tank 100. The stirring state parameters of the waste liquid inside the tank include the supernatant level of the waste liquid inside the stirred tank 100, which is the supernatant liquid level of the waste liquid inside the stirred tank 100 after the stirring operation. Specifically, the supernatant level of the waste liquid inside the tank is collected by a level gauge. By collecting the supernatant level of the waste liquid in the vessel, it is easy to determine the real-time supernatant level of the waste liquid in the vessel 100 during the stirring process, thereby facilitating the determination of the degree of heavy metal ion precipitation in the waste liquid in the vessel 100.

[0050] Further, the step of performing waste liquid agitation difference processing on the waste liquid agitation state parameters and preset agitation state parameters to obtain waste liquid agitation difference includes: calculating the difference between the waste liquid agitation supernatant level and the preset waste liquid supernatant level to obtain the waste liquid agitation supernatant level difference. In this embodiment, the waste liquid agitation state parameters are the current agitation status of the heavy metal waste liquid in the agitated vessel 100, that is, the waste liquid agitation state parameters are the reaction status of the waste liquid in the agitated vessel 100 during the agitation process. By collecting the waste liquid agitation state parameters, it is convenient to determine the current agitation reaction of the waste liquid in the agitated vessel 100 for processing. The preset agitation state parameters are the reference agitation status of the heavy metal waste liquid in the agitated vessel 100, that is, the preset agitation state parameters are the standard reaction status of the waste liquid in the agitated vessel 100 during the agitation process. By performing differential processing on the stirring state parameters of the waste liquid in the reactor and the preset stirring state parameters, the degree of difference in the reaction state of the waste liquid in the stirred reactor 100 during the stirring process can be easily determined. The stirring state parameters of the waste liquid in the reactor include the supernatant level of the waste liquid in the stirred reactor 100, which is the supernatant liquid level of the waste liquid in the stirred reactor 100 after the stirring operation. By collecting the supernatant level of the waste liquid in the reactor, the real-time supernatant liquid level position of the waste liquid in the stirred reactor 100 during the stirring process can be easily determined, thereby facilitating the determination of the degree of heavy metal ion precipitation in the waste liquid in the stirred reactor 100. By calculating the difference between the supernatant level of the waste liquid in the reactor and the preset supernatant level, the completeness of the removal of heavy metal ions by the waste liquid in the stirred reactor 100 through chemical reaction can be easily determined.

[0051] Furthermore, the step of sending a sludge discharge start / stop signal to the waste liquid pretreatment controller based on the waste liquid agitation difference component to adjust the working mode of the sludge discharge valve 400 includes: detecting whether the waste liquid agitation supernatant level difference is greater than or equal to a preset supernatant level difference; and when the waste liquid agitation supernatant level difference is greater than or equal to the preset supernatant level difference, sending a sludge discharge start signal to the waste liquid pretreatment controller. In this embodiment, the waste liquid agitation difference component is obtained based on the waste liquid agitation state parameters in the vessel and the preset agitation state parameters. The waste liquid agitation state parameters in the vessel refer to the current agitation status of the heavy metal waste liquid in the agitated vessel 100, that is, the waste liquid agitation state parameters in the vessel refer to the reaction status of the waste liquid in the agitated vessel 100 during the agitation process. By collecting the waste liquid agitation state parameters in the vessel, it is convenient to determine the current agitation reaction of the waste liquid in the agitated vessel 100 for treatment. The preset stirring state parameters are reference stirring conditions for the heavy metal waste liquid inside the stirred tank 100, i.e., the preset stirring state parameters are the standard reaction state of the waste liquid inside the stirred tank 100 during the stirring process. By processing the waste liquid stirring state difference between the stirred state parameters and the preset stirring state parameters, it is easy to determine the degree of difference in the reaction state of the waste liquid inside the stirred tank 100 during the stirring process. After obtaining the waste liquid stirring state difference, it is easy to determine whether the current reaction of the waste liquid inside the stirred tank 100 during the stirring process is complete, thereby facilitating the determination of whether the heavy metals in the waste liquid inside the stirred tank 100 have completely precipitated, and thus facilitating the removal of heavy metals from the waste liquid by controlling the opening and closing state of the sludge discharge valve 400. The stirred state parameters of the waste liquid inside the tank include the supernatant level of the waste liquid inside the stirred tank 100, which is the supernatant liquid level of the waste liquid inside the stirred tank 100 after the stirring operation. By collecting the supernatant level of the waste liquid in the stirred tank, it is easy to determine the real-time supernatant liquid level position of the waste liquid in the stirred tank 100 during the stirring process, thereby facilitating the determination of the degree of heavy metal ion precipitation in the waste liquid in the stirred tank 100. By calculating the difference between the supernatant level of the waste liquid during stirring and the preset supernatant level, it is easy to determine the completeness of the removal of heavy metal ions by the waste liquid in the stirred tank 100 through chemical reaction. If the difference in the supernatant level of the stirred waste liquid is greater than or equal to the preset supernatant level difference, it indicates that the supernatant liquid and precipitate of the waste liquid in the stirred tank 100 are completely separated after stirring, that is, it indicates that the heavy metal ions in the waste liquid in the stirred tank 100 form an insoluble precipitate after stirring and settle at the bottom. At this time, a sludge discharge start signal is sent to the waste liquid pretreatment controller to facilitate the discharge of the heavy metal ion precipitate formed in the waste liquid in the stirred tank 100.

[0052] In another embodiment, after detecting whether the waste liquid agitated supernatant level difference is greater than or equal to a preset supernatant level difference, the method further includes: when the waste liquid agitated supernatant level difference is less than the preset supernatant level difference, sending a sludge discharge shutdown signal to the waste liquid pretreatment controller. In this embodiment, the waste liquid agitated supernatant level difference being less than the preset supernatant level difference indicates that the supernatant liquid and precipitate of the waste liquid in the stirred tank 100 are mixed together after agitation, which means that the heavy metal ions in the waste liquid in the stirred tank 100 have not completely settled after agitation. At this time, sending a sludge discharge shutdown signal to the waste liquid pretreatment controller avoids discharging the waste liquid in the stirred tank 100 that has not yet been cleared of heavy metal ions.

[0053] In the actual process of removing heavy metal ions from PCB waste liquid, the pH value of the chemical reaction after adding lime cannot be directly read and needs to be indirectly collected by a sensor. However, due to the limited detection accuracy of the sensor, the pH value sampling deviation is often serious, resulting in excessive materials used for removing heavy metal ions from the waste liquid.

[0054] To reduce the amount of material required for heavy metal ion removal, the step of sending a sludge discharge on / off signal to the waste liquid pretreatment controller based on the waste liquid agitation differential to adjust the working mode of the sludge discharge valve 400 also includes the following steps:

[0055] Obtain the temperature difference of the vessel body of the stirred tank 100;

[0056] Detect whether the temperature difference in the vessel body is greater than or equal to the preset temperature difference;

[0057] When the temperature difference of the vessel body is greater than or equal to the preset temperature difference, an inward reduction signal is sent to the waste liquid pretreatment controller.

[0058] In this embodiment, the temperature difference of the vessel body is the temperature difference between the inner and outer walls of the stirred vessel 100, that is, the temperature difference of the vessel body is the degree of difference between the internal waste liquid temperature of the stirred vessel 100 and the ambient temperature outside the vessel body. Specifically, the temperature of the inner and outer walls of the stirred vessel is collected by a temperature sensor to facilitate the determination of the intensity of the chemical reaction between the waste liquid and lime inside the stirred vessel 100. The temperature difference of the vessel body being greater than or equal to the preset temperature difference indicates that the chemical reaction between the waste liquid and lime in the stirred vessel 100 is strong, that is, that the contact between the waste liquid and lime in the stirred vessel 100 is sufficient, and that the amount of lime injected into the stirred vessel 100 is close to sufficient. At this time, by sending an inward reduction signal to the waste liquid pretreatment controller, the rate of lime injection into the stirred vessel 100 is reduced. At the same time, the position of lime injection into the stirred vessel 100 is also adjusted inward, that is, the position where lime and waste liquid in the stirred vessel 100 begin to contact is adjusted to be closer to the stirring paddle 320, so that the lime can be fully diffused through the high turbulence velocity at the center of the stirring paddle 320, thereby reducing the amount of lime used.

[0059] Further, the step of detecting whether the temperature difference in the vessel body is greater than or equal to a preset temperature difference also includes:

[0060] When the temperature difference of the vessel body is less than the preset temperature difference, the bubble diffusion area of ​​the waste liquid surface of the stirring vessel 100 is obtained;

[0061] The bubble diffusion rate is obtained based on the bubble diffusion area on the surface of the waste liquid.

[0062] Detect whether the bubble diffusion rate is less than or equal to a preset diffusion rate;

[0063] When the bubble diffusion rate is less than or equal to the preset diffusion rate, a signal to increase the injection rate to the edge is sent to the waste liquid pretreatment controller.

[0064] In this embodiment, the temperature difference in the vessel body is less than the preset temperature difference, indicating that the chemical reaction between the waste liquid and lime in the stirred vessel 100 is less intense. At this time, by collecting the bubble diffusion area on the surface of the waste liquid—specifically, by setting a CCD camera at the feed port of the stirred vessel to collect images of the waste liquid surface—the bubble diffusion area on the surface of the waste liquid is obtained. This facilitates the determination of the size of the bubble region generated by the heat released during the reaction between the waste liquid and lime in the stirred vessel 100, thereby determining the degree of difference in the molar number between the waste liquid and lime in the stirred vessel 100. The bubble diffusion rate is obtained based on the bubble diffusion area on the surface of the waste liquid. The bubble diffusion rate reflects how quickly the bubbles move towards the edge of the vessel body during the reaction between the waste liquid and lime in the stirred vessel 100, thus reflecting the diffusion rate of lime in the waste liquid of the stirred vessel 100. If the bubble diffusion rate is less than or equal to the preset diffusion rate, it indicates that the lime distribution in the waste liquid of the stirred tank 100 is too concentrated in the center, which cannot ensure that all heavy metal ions in the waste liquid of the stirred tank 100 will form precipitates, and more lime is needed. At this time, by sending an edge-injection signal to the waste liquid pretreatment controller, the rate of lime injection into the stirred tank 100 is increased. At the same time, the position of lime injection into the stirred tank 100 is extended to the edge of the tank body, that is, the contact position between lime and waste liquid in the stirred tank 100 is gradually moved away from the stirring paddle 320, so as to form more heavy metals into precipitates with a limited amount of lime, and further reduce the amount of lime used.

[0065] In another embodiment, when the bubble diffusion rate is greater than the preset diffusion rate, step S300 is executed. At this time, the waste liquid in the stirred tank 100 comes into full contact with the lime, which facilitates the discharge of more heavy metal sludge.

[0066] The embodiments described above are merely illustrative of several implementations of this disclosure, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this disclosure, and these all fall within the protection scope of this disclosure. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A method for treating heavy metals in PCB wastewater based on a high-concentration wastewater pretreatment device, characterized in that, A high-concentration wastewater pretreatment device is used to precipitate and remove heavy metals from PCB wastewater. The high-concentration wastewater pretreatment device includes: A stirred tank for containing PCB waste liquid; A pH probe is installed on the stirred tank and is used to collect the acid and alkalinity value of the waste liquid in the stirred tank. A stirring assembly, comprising a stirring motor and a stirring paddle, wherein the rotating shaft of the stirring motor is connected to the stirring paddle, the stirring paddle is located inside the stirring vessel, and the stirring paddle is used to stir the PCB waste liquid to form heavy metal sludge at the bottom of the stirring vessel; A sludge discharge valve is connected to the sludge discharge port at the bottom of the mixing vessel to discharge heavy metal sludge from the mixing vessel. The method for treating heavy metals in PCB waste liquid includes: The waste liquid inside the stirred tank is neutralized by injecting lime into the stirred tank. Obtain the stirring state parameters of the waste liquid inside the stirred tank, including obtaining the acid-base value of the waste liquid inside the stirred tank; The stirring state parameters of the waste liquid in the reactor are compared with the preset stirring state parameters to obtain the waste liquid stirring state difference, including calculating the difference between the acid and alkalinity values ​​of the waste liquid in the reactor and the preset acid and alkalinity values ​​of the waste liquid to obtain the waste liquid stirring state acid-base difference. Based on the waste liquid agitation difference, a sludge discharge start / stop signal is sent to the waste liquid pretreatment controller to adjust the working mode of the sludge discharge valve, including: detecting whether the waste liquid agitation acid-base difference is greater than or equal to a preset acid-base difference; when the waste liquid agitation acid-base difference is greater than or equal to the preset acid-base difference, a sludge discharge start signal is sent to the waste liquid pretreatment controller; when the waste liquid agitation acid-base difference is less than the preset acid-base difference, a sludge discharge stop signal is sent to the waste liquid pretreatment controller. The step of sending a sludge discharge on / off signal to the waste liquid pretreatment controller based on the waste liquid agitation differential to adjust the working mode of the sludge discharge valve also includes the following steps: The temperature difference of the stirred vessel is obtained, which is the temperature difference between the inner and outer walls of the stirred vessel; Detect whether the temperature difference in the vessel body is greater than or equal to the preset temperature difference; When the temperature difference of the vessel is greater than or equal to the preset temperature difference, an inward reduction signal is sent to the waste liquid pretreatment controller to reduce the rate of lime injection into the stirred vessel, and at the same time, the position of lime injection into the stirred vessel is moved inward to adjust the position where lime and waste liquid in the stirred vessel begin to contact each other to be closer to the stirring paddle. When the temperature difference of the vessel body is less than the preset temperature difference, the bubble diffusion area of ​​the waste liquid surface in the stirred vessel is obtained; The bubble diffusion rate is obtained based on the bubble diffusion area on the surface of the waste liquid. Detect whether the bubble diffusion rate is less than or equal to a preset diffusion rate; When the bubble diffusion rate is less than or equal to the preset diffusion rate, an edge-injection signal is sent to the waste liquid pretreatment controller to increase the rate of lime injection into the stirred tank, and at the same time, the position of lime injection into the stirred tank is extended towards the edge of the tank body. When the bubble diffusion rate is greater than the preset diffusion rate, the following is executed: "Send a sludge discharge start / stop signal to the waste liquid pretreatment controller according to the waste liquid agitation difference to adjust the working mode of the sludge discharge valve".

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