A system and method for recycling waste acid and waste base

Abstract

The application belongs to the technical field of industrial wastewater resource treatment, and relates to a waste acid and waste alkali recycling system and method.The waste acid and waste alkali recycling system comprises a waste liquid collection module, a fluorine-containing wastewater treatment module, an acid-alkali neutralization module and a non-fluorine-containing wastewater treatment module.The waste liquid collection module is used for collecting waste acid and waste alkali respectively;part of the waste acid is introduced into the fluorine-containing wastewater treatment module to remove fluorine ions in the fluorine-containing wastewater;another part of the waste acid and part of the waste alkali are introduced into the acid-alkali neutralization module to perform acid-alkali neutralization; and another part of the waste alkali is introduced into the non-fluorine-containing wastewater treatment module to neutralize the acidity of the non-fluorine-containing wastewater.The system uses self-produced waste liquid in the factory to achieve waste treatment with waste, replaces externally purchased water treatment reagents, reduces treatment cost, completes fluorine ion removal and water quality adjustment in advance, reduces the operation load of the comprehensive wastewater treatment system at the rear end, and realizes the overall coordination of the collaborative pretreatment of various types of wastewater, and has good environmental protection benefits and economic practical value.

Description

Technical Field

[0001] This application relates to the field of industrial wastewater resource treatment technology, specifically to a waste acid and waste alkali recycling system and method. Background Technology

[0002] Currently, ion exchange technology is widely used in industrial pure water preparation and water purification processes to purify water. After long-term operation, ion exchange resins require periodic regeneration using acid and alkali reagents, generating large amounts of highly concentrated acidic and alkaline wastewater. In existing production models, most companies simply mix and neutralize these two types of regenerated wastewater before discharging them, without utilizing the effective components within the wastewater. This not only results in a serious waste of wastewater resources but also easily leads to strong acid and alkaline water quality impacts on downstream wastewater treatment systems due to large fluctuations in wastewater concentration and incomplete neutralization, increasing subsequent water treatment operating costs.

[0003] Meanwhile, industrial production processes also generate large amounts of fluoride-containing wastewater. Fluoride ions are strictly controlled characteristic pollutants, and if not effectively treated, they can easily cause water pollution. Currently, the industry mostly uses purchased calcium hydroxide, lime, and other reagents for precipitation and defluoridation to treat fluoride-containing wastewater. The purchase cost of these reagents is high, and long-term use results in a heavy economic burden. Furthermore, conventional defluoridation processes are greatly affected by the quality of the influent water, and their defluoridation stability is poor.

[0004] In addition, the factory's daily production also generates a large amount of ordinary non-fluoride-containing industrial wastewater. This type of wastewater is mostly weakly acidic and needs to be adjusted in pH before entering centralized wastewater treatment facilities. Current technology usually involves directly adding purchased alkaline agents to adjust the pH, resulting in a large consumption of agents and failing to achieve the overall allocation and coordinated treatment of various types of wastewater in the factory.

[0005] In summary, the existing wastewater treatment methods in the plant area are independent of each other. The disposal of ion exchange regeneration waste liquid is extensive and has a low resource utilization rate. The treatment of fluoride-containing wastewater relies on purchased reagents, which is costly. The pretreatment processes for various types of wastewater are scattered and disorderly, which easily leads to large fluctuations in the quality and quantity of influent to the downstream integrated wastewater treatment system. The overall sewage treatment system has insufficient operational stability and it is difficult to balance the environmental protection effect with the economic benefits of enterprise production and operation. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a waste acid and alkali recycling system and method that can achieve the coordinated treatment of fluoride-containing wastewater, acid and alkali waste liquids, and ordinary non-fluoride-containing wastewater from the factory area. This not only improves the stability of pretreatment compliance of various types of wastewater, but also reduces the amount of hazardous waste liquids discharged. While ensuring that the wastewater treatment meets the standards, it significantly improves the overall economic and environmental benefits of the enterprise's wastewater treatment.

[0007] On the one hand, this application provides a waste acid and waste alkali recycling system, which is applied to a pure water preparation system. The pure water preparation system is provided with a cation bed and an anion bed. The system is characterized by including a waste liquid collection module, a fluoride-containing wastewater treatment module, an acid-base neutralization module, and a non-fluoride-containing wastewater treatment module.

[0008] The waste liquid collection module includes a waste acid collection tank and a waste alkali collection tank. The waste acid collection tank is connected to the cation bed and is used to collect and store the waste acid generated by the acid washing failure of the cation bed. The waste alkali collection tank is connected to the anion bed and is used to collect and store the waste alkali generated by the alkali washing failure of the anion bed.

[0009] The fluoride-containing wastewater treatment module includes a reaction tank, a fluoride-containing wastewater collection tank, and a sedimentation tank. The reaction tank is connected to the waste acid collection tank so that the waste acid is transported to the reaction tank and reacts with an alkaline solution to generate calcium hydroxide. The fluoride-containing wastewater collection tank is connected to the reaction tank so that the calcium hydroxide is transported to the fluoride-containing wastewater collection tank and reacts with fluoride ions in the fluoride-containing wastewater to generate calcium fluoride precipitate. The sedimentation tank is connected to the fluoride-containing wastewater collection tank to separate the calcium fluoride precipitate from the supernatant.

[0010] The acid-base neutralization module includes a neutralization tank and a buffer tank. The neutralization tank is connected to the waste acid collection tank and the waste alkali collection tank so that the waste acid and the waste alkali are transported to the neutralization tank and undergo an acid-base neutralization reaction to generate neutralized effluent. The buffer tank is connected to the neutralization tank and is used to homogenize the water quality and buffer the water volume of the neutralized effluent.

[0011] The non-fluoride wastewater treatment module includes a pH adjustment tank, which is connected to the waste alkali collection tank so that the waste alkali is transported to the pH adjustment tank and neutralizes the acidity of the non-fluoride wastewater.

[0012] In an optional embodiment, the sedimentation tank, the buffer tank, and the pH adjustment tank are all connected to a comprehensive wastewater treatment system for post-treatment of the supernatant in the sedimentation tank, the neutralized effluent in the buffer tank, and the non-fluoride-containing wastewater adjusted to neutral in the pH adjustment tank, and discharged after passing water quality testing.

[0013] In an optional embodiment, the reaction tank is provided with a first dosing device for adding an alkaline solution to the reaction tank.

[0014] In an optional embodiment, the non-fluoride wastewater treatment module further includes an emergency acid storage tank for storing acidic solutions. The emergency acid storage tank is connected to the pH adjustment tank and is used to add acidic solutions to the pH adjustment tank when the non-fluoride wastewater is alkaline, so as to adjust the non-fluoride wastewater to neutral.

[0015] In an optional embodiment, the waste acid and alkali recycling system further includes a detection module, a flow regulation module, and a control module. The control module receives the detection signal from the detection module and controls the flow regulation module, the first dosing device, and the emergency acid storage tank according to the detection signal.

[0016] In an optional embodiment, the detection module includes a first flow meter, a second flow meter, a calcium ion concentration analyzer, a fluoride ion concentration analyzer, a first pH meter, a second pH meter, and a third pH meter;

[0017] The first flow meter and the calcium ion concentration analyzer are installed at the inlet of the reaction tank to detect the calcium ion content in the reaction tank.

[0018] The second flow meter and the fluoride ion concentration analyzer are installed at the inlet of the fluoride-containing wastewater collection tank to detect the fluoride ion content in the fluoride-containing wastewater collection tank.

[0019] The first pH meter is installed in the fluoride-containing wastewater collection tank to detect the pH value of the fluoride-containing wastewater;

[0020] The second pH meter is installed in the neutralization tank to detect the pH value of the neutralized effluent;

[0021] The third pH meter is installed in the pH adjustment tank and is used to detect the pH value of the non-fluoride wastewater.

[0022] In an optional embodiment, the flow control module includes a first valve, a second valve, and a third valve;

[0023] The first valve is located at the outlet of the waste acid collection tank. The control module controls the first valve according to the pH value of the fluoride-containing wastewater, the fluoride ion content, and the pH value of the neutralized effluent in the neutralization tank, so as to adjust the flow direction and flow rate of the waste acid.

[0024] The second valve is located at the outlet of the waste alkali collection tank. The control module controls the second valve according to the pH value of the neutralized effluent in the neutralization tank and the pH value of the non-fluoride wastewater in the pH adjustment tank, so as to adjust the flow direction and flow rate of the waste alkali.

[0025] The third valve is located at the outlet of the emergency acid storage tank. The control module controls the third valve according to the pH value of the non-fluoride wastewater in the pH adjustment tank to adjust the flow rate of the acidic solution.

[0026] On the other hand, this application provides a method for recycling waste acid and alkali, comprising the following steps:

[0027] Provide waste acid and alkali recycling systems;

[0028] Waste acid generated from the failed pickling of the cation exchange bed is collected in the waste acid collection tank; waste alkali generated from the failed alkaline washing of the anion exchange bed is collected in the waste alkali collection tank; fluoride-containing wastewater is collected in the fluoride-containing wastewater collection tank; and non-fluoride-containing wastewater is collected in the pH adjustment tank.

[0029] A portion of the waste acid is transported to a reaction tank, and an alkaline solution is added to react the waste acid with the alkaline solution to generate calcium hydroxide.

[0030] The calcium hydroxide is added to the fluoride-containing wastewater collection tank so that the fluoride ions in the fluoride-containing wastewater react with the calcium hydroxide to form calcium fluoride precipitate. The calcium fluoride precipitate is then separated from the supernatant in a sedimentation tank, thereby removing the fluoride ions from the fluoride-containing wastewater.

[0031] A portion of the waste acid and waste alkali are transported to a neutralization tank, where they undergo a neutralization reaction to generate neutralized effluent. The neutralized effluent is then transported to a buffer tank to homogenize the water quality and buffer the water volume.

[0032] A portion of the waste alkali is transported to the pH adjustment tank to neutralize the acidity of the non-fluoride wastewater.

[0033] In an optional embodiment, the required calcium hydroxide content is calculated based on the fluoride ion content in the fluoride wastewater collection tank, thereby calculating the content of the waste acid and the alkaline solution to be transported to the reaction tank.

[0034] In an optional embodiment, the waste acid in the waste acid collection tank is preferentially transported to the reaction tank to prepare calcium hydroxide, and the remaining waste acid is transported to the neutralization tank for neutralization reaction; the waste alkali in the waste alkali collection tank is preferably transported to the neutralization tank for neutralization reaction, and the remaining waste alkali is transported to the pH adjustment tank.

[0035] As described above, compared with the prior art, the waste acid and waste alkali recycling system and method provided in this application have at least the following beneficial effects:

[0036] The waste acid and alkali recycling system provided in this application fully utilizes calcium ions in waste acid to prepare calcium hydroxide reagent on-site for the defluorination treatment of fluoride-containing wastewater, replacing traditional externally purchased defluorination reagents, significantly reducing reagent procurement costs, realizing the resource utilization of waste liquid, and practicing the environmental protection concept of treating waste with waste. The waste alkali is used separately according to its quality: part of it is used to neutralize the waste acid, and the other part is used to adjust the pH of non-fluoride-containing wastewater, eliminating the need for additional emergency alkali dosing equipment, simplifying the system structure, and reducing equipment investment. It realizes the integrated and coordinated treatment of fluoride-containing wastewater, acid and alkali waste liquid, and non-fluoride-containing wastewater in the plant area. The process flow layout is reasonable and the degree of automation control is high. It not only improves the stability of the pretreatment of various types of wastewater to meet standards, but also reduces the discharge of hazardous waste liquid. While ensuring that the wastewater treatment meets the standards, it significantly improves the overall economic and environmental benefits of the enterprise's wastewater treatment.

[0037] The waste acid and alkali recycling method of this application utilizes the aforementioned waste acid and alkali recycling system to recycle and reuse waste acid and alkali, thus possessing the same beneficial effects as described above. Attached Figure Description

[0038] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application 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.

[0039] Figure 1 The diagram shown is a structural schematic of a waste acid and waste alkali recycling system provided in Embodiment 1 of this application.

[0040] Figure 2 The diagram shown is a flowchart illustrating a method for recycling acid waste alkali according to Embodiment 2 of this application.

[0041] In the diagram: 01, Cation bed; 02, Anion bed; 03, Integrated wastewater treatment system; 04, Fluoride-containing wastewater production unit; 05, Non-fluoride-containing wastewater production unit; 11, Waste acid collection tank; 12, Waste alkali collection tank; 21, Reaction tank; 211, First dosing device; 22, Fluoride-containing wastewater collection tank; 23, Sedimentation tank; 31, Neutralization tank; 32, Buffer tank; 41, pH adjustment tank; 42, Emergency acid storage tank; 51, First flow meter; 52, Second flow meter; 53, Calcium ion concentration analyzer; 54, Fluoride ion concentration analyzer; 55, First pH meter; 56, Second pH meter; 57, Third pH meter; 61, First valve; 62, Second valve; 63, Third valve; 7, Control module. Detailed Implementation

[0042] To make the technical objectives, technical solutions, and technical effects of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0043] Therefore, the following detailed description of embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] In the description of this application, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0045] In the description of this application, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, for example, referring to both fixed connections and detachable connections. Furthermore, the descriptions using terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples" indicate that a specific feature, structure, material, or characteristic described in connection with an implementation or example is included in at least one implementation or example of this application. In this specification, illustrative expressions of the above terms do not necessarily refer to the same implementation or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more implementations or examples.

[0046] Example 1

[0047] To address the problems of severe waste liquid resource waste and high reagent procurement costs in the existing technologies described above, this embodiment provides a waste acid and alkali recycling system applied to a pure water preparation system. This system aims to improve the overall economic and environmental benefits of enterprise wastewater treatment. (Refer to...) Figure 1 The pure water preparation system is equipped with a cation bed and anion bed. The system includes a waste liquid collection module 1, a fluoride-containing wastewater treatment module 2, an acid-base neutralization module 3, and a non-fluoride-containing wastewater treatment module 4.

[0048] The waste liquid collection module 1 includes a waste acid collection tank 11 and a waste alkali collection tank 12. The waste acid collection tank 11 is connected to the cation bed 01 and is used to collect and store the waste acid generated by the acid washing failure cation bed 01. The waste alkali collection tank 12 is connected to the anion bed 02 and is used to collect and store the waste alkali generated by the alkali washing failure anion bed 02.

[0049] The fluoride-containing wastewater treatment module 2 includes a reaction tank 21, a fluoride-containing wastewater collection tank 22, and a sedimentation tank 23. The reaction tank 21 is connected to the waste acid collection tank 11 so that the waste acid is transported to the reaction tank 21 and reacts with an alkaline solution to generate calcium hydroxide. The fluoride-containing wastewater collection tank 22 is connected to the reaction tank 21 so that the calcium hydroxide is transported to the fluoride-containing wastewater collection tank 22 and reacts with fluoride ions in the fluoride-containing wastewater to generate calcium fluoride precipitate. The sedimentation tank 23 is connected to the fluoride-containing wastewater collection tank 22 to separate the calcium fluoride precipitate from the supernatant.

[0050] The acid-base neutralization module 3 includes a neutralization tank 31 and a buffer tank 32. The neutralization tank 31 is connected to the waste acid collection tank 11 and the waste alkali collection tank 12 so that the waste acid and the waste alkali are transported to the neutralization tank 31 and undergo an acid-base neutralization reaction to generate neutralized effluent. The buffer tank 32 is connected to the neutralization tank 31 and is used to homogenize the water quality and buffer the water quantity of the neutralized effluent.

[0051] The non-fluoride wastewater treatment module 4 includes a pH adjustment tank 41, which is connected to the waste alkali collection tank 12 so that the waste alkali is transported to the pH adjustment tank 41 and neutralizes the acidity of the non-fluoride wastewater.

[0052] In practical applications, the fluoride-containing wastewater treatment module 2 utilizes calcium ions from waste acid to prepare calcium hydroxide reagent on-site for fluoride removal from fluoride-containing wastewater, replacing traditional externally purchased defluorination reagents. This significantly reduces reagent procurement costs, achieves resource utilization of waste liquid, and practices the environmental protection concept of treating waste with waste. Waste alkali is used in separate streams: one part is used to neutralize waste acid, and the other part is used to adjust the pH of non-fluoride-containing wastewater. No additional emergency alkali dosing equipment is needed, simplifying the system structure and reducing equipment investment. This system achieves integrated and coordinated treatment of fluoride-containing wastewater, acid and alkali waste liquid, and non-fluoride-containing wastewater in the plant area. The process flow layout is reasonable, and the degree of automation is high. It not only improves the stability of pretreatment compliance for various types of wastewater but also reduces the discharge of hazardous waste liquid. While ensuring that wastewater treatment meets standards, it significantly improves the overall economic and environmental benefits of the enterprise's wastewater treatment.

[0053] In this embodiment, the cation exchange bed 01 in the pure water preparation system is used to remove various cations such as calcium, magnesium, and sodium ions from the raw water, thereby reducing the hardness and metal ion content of the raw water and initially purifying the water quality. After the cation exchange bed 01 becomes ineffective, i.e., after the ion exchange resin in the cation exchange bed 01 becomes saturated, the ion exchange resin is generally cleaned with an acidic agent, and the regeneration of the ion exchange resin produces waste acid rich in calcium ions. The anion exchange bed 02 is used to remove anions such as sulfate, chloride, and bicarbonate from the raw water, further removing various acid radical impurities from the raw water and improving the purity of the effluent. After the ion exchange resin in the anion exchange bed 02 becomes ineffective, the ion exchange resin is generally cleaned with an alkaline agent, and the regeneration of the ion exchange resin produces waste alkali.

[0054] Waste liquid collection module 1 includes a waste acid collection tank 11 and a waste alkali collection tank 12. The waste acid collection tank 11 is connected to the cation bed 01 and is used to collect and store the waste acid generated by the failed pickling cation bed 01. The waste alkali collection tank 12 is connected to the anion bed 02 and is used to collect and store the waste alkali generated by the failed alkali washing anion bed 02. The waste liquid collection module 1 is designed to store waste acid and waste alkali, enabling the on-demand and quantitative external transportation of waste acid and alkali, achieving orderly diversion and distribution of waste acid, and reserving buffer time for equipment maintenance and process adjustment, thus ensuring the stability of the entire waste acid and waste alkali recycling system.

[0055] The fluoride-containing wastewater treatment module 2 includes a reaction tank 21, a fluoride-containing wastewater collection tank 22, and a sedimentation tank 23. The reaction tank 21 is connected to the waste acid collection tank 11 so that the waste acid is transported to the reaction tank 21 and reacts with the alkaline solution to generate calcium hydroxide. The fluoride-containing wastewater collection tank 22 is connected to the reaction tank 21 so that the calcium hydroxide is transported to the fluoride-containing wastewater collection tank 22 and reacts with the fluoride ions in the fluoride-containing wastewater to generate calcium fluoride precipitate. The sedimentation tank 23 is connected to the fluoride-containing wastewater collection tank 22 to separate the calcium fluoride precipitate from the supernatant.

[0056] The alkaline solution can be any of sodium hydroxide solution, potassium hydroxide solution, or other suitable alkaline solutions, used to react with calcium ions in waste acid to produce calcium hydroxide. Preferably, the alkaline solution is sodium hydroxide solution, as sodium hydroxide reacts completely with calcium ions without any excess solid impurities, thus ensuring reaction efficiency and product purity.

[0057] In this embodiment, the reaction tank 21 is equipped with a first dosing device 211 for adding an alkaline solution to the reaction tank 21. The first dosing device 211 can be any one of a metering pump dosing assembly, an integrated automatic dosing device, or other suitable dosing equipment. Preferably, the first dosing device 211 is a linkage metering dosing device, which can automatically match the dosage of the drug solution based on the online detection data of calcium ions in the fluoride wastewater collection tank 22, so as to achieve precise control of the drug ratio.

[0058] The fluoride-containing wastewater generated by the fluoride-containing wastewater production unit 04 is collected and stored in the fluoride-containing wastewater collection tank 22. The fluoride-containing wastewater is mostly acidic, but calcium hydroxide has high solubility in an acidic environment, making it difficult to quickly form calcium fluoride precipitate. Therefore, in this embodiment, calcium hydroxide plays two roles. First, as a strong alkali, calcium hydroxide can directly neutralize the hydrogen ions in the acidic fluoride-containing wastewater, adjusting the pH value of the fluoride-containing wastewater to the neutral range. After the fluoride-containing wastewater is neutralized, the calcium ions released from calcium hydroxide directly react with the fluoride ions in the fluoride-containing wastewater to form calcium fluoride precipitate. This design can ensure that fluoride ions and calcium ions fully react to form calcium fluoride precipitate, thereby improving the defluorination efficiency.

[0059] The acid-base neutralization module 3 includes a neutralization tank 31 and a buffer tank 32. The neutralization tank 31 is connected to the waste acid collection tank 11 and the waste alkali collection tank 12 so that the waste acid and waste alkali are transported to the neutralization tank 31 and the two undergo an acid-base neutralization reaction to generate neutralized effluent. The buffer tank 32 is connected to the neutralization tank 31 and is used to homogenize the water quality and buffer the water volume of the neutralized effluent generated in the neutralization tank 31.

[0060] In this embodiment, the buffer tank 32 is a large-capacity water storage tank. It achieves the regulation of water volume and quality homogenization through volumetric water storage, smoothly transports water flow, reduces hydraulic impact, stabilizes the water inlet conditions of downstream processes, and plays the role of water volume buffering, water quality homogenization, and pressure stabilization.

[0061] The non-fluoride wastewater treatment module 4 includes a pH adjustment tank 41, which is used to collect and store the non-fluoride wastewater generated by the non-fluoride wastewater production unit 05. The pH adjustment tank 41 is connected to the waste alkali collection tank 12 so that the waste alkali is transported to the pH adjustment tank 41 and neutralizes the acidity of the non-fluoride wastewater.

[0062] In this embodiment, the non-fluoride wastewater treatment module 4 also includes an emergency acid storage tank 42 for storing acidic solutions. The emergency acid storage tank 42 is connected to the pH adjustment tank 41 and is used to add acidic solutions to the pH adjustment tank 41 when the non-fluoride wastewater is alkaline, so as to adjust the non-fluoride wastewater to neutral.

[0063] The waste acid and alkali recycling system also includes a detection module 5, a flow regulation module 6, and a control module 7. The control module 7 receives the detection signals from the detection module 5 and controls the flow regulation module, the first dosing device 211, the second dosing device, and the emergency acid storage tank 42 according to the detection signals. The detection module 5 includes a first flow meter 51, a second flow meter 52, a calcium ion concentration analyzer 53, a fluoride ion concentration analyzer 54, a first pH meter 55, a second pH meter 56, and a third pH meter 57. The flow regulation module 6 includes a first valve 61, a second valve 62, and a third valve 63.

[0064] In this embodiment, a first flow meter 51 and a calcium ion concentration analyzer 53 are installed at the inlet of the reaction tank 21 to detect the calcium ion content in the reaction tank 21; a second flow meter 52 and a fluoride ion concentration analyzer 54 are installed at the inlet of the fluoride-containing wastewater collection tank 22 to detect the fluoride ion content in the fluoride-containing wastewater collection tank 22; a first pH meter 55 is installed in the fluoride-containing wastewater collection tank 22 to detect the pH value of the fluoride-containing wastewater; a second pH meter 56 is installed in the neutralization tank 31 to detect the pH value of the neutralized effluent; and a third pH meter 57 is installed in the pH adjustment tank 41 to detect the pH value of the non-fluoride-containing wastewater.

[0065] The first flow meter 51 and the second flow meter 52 can be electromagnetic flow meters, ultrasonic flow meters or other suitable flow detection devices. Preferably, the first flow meter 51 and the second flow meter 52 are electromagnetic flow meters. Electromagnetic flow meters have advantages such as strong corrosion resistance, anti-clogging, accurate measurement, low pressure loss and easy linkage and automatic control. They can perfectly meet the online flow detection needs of corrosive sewage such as waste acid and fluoride-containing wastewater.

[0066] The calcium ion concentration analyzer 53 can be a calcium ion selective electrode detector, an online calcium concentration analyzer, an atomic absorption spectrophotometer, or other suitable ion concentration detection device. In this embodiment, an online calcium ion selective electrode analyzer is preferred. This device can realize online real-time detection, has a rapid response, is suitable for waste acid conditions, and can be connected to the control module 7 to complete automatic dosage adjustment.

[0067] The fluoride ion concentration analyzer 54 can be a fluoride ion selective electrode detector, an online fluoride ion analyzer, an ion chromatograph, etc. In this embodiment, an online fluoride ion selective electrode analyzer is preferred. This device can detect in real time online, respond quickly, adapt to fluoride-containing wastewater conditions, and can be linked with the control module 7 to accurately regulate the dosage of reagents. It is easy to operate and maintain, has stable detection, and ensures that the fluoride removal effect is stable and meets the standards.

[0068] The first pH meter 55, the second pH meter 56, and the third pH meter 57 can be industrial pH electrode detectors, precision acidity meters, or other suitable pH value detection devices. In this embodiment, an industrial pH electrode detector is preferred. This detector can detect the acidity and alkalinity of water in real time without interruption. It is resistant to acid and alkali corrosion, has a fast response speed, and can also be linked with the control module 7 to automatically adjust the dosage of reagents. It is accurate in measurement and convenient in operation and maintenance, and is suitable for the entire wastewater resource utilization treatment process.

[0069] The first valve 61 is located at the outlet of the waste acid collection tank 11. The control module 7 controls the first valve 61 according to the fluoride ion content in the fluoride wastewater collection tank 22 and the pH value of the neutralized effluent generated in the neutralization tank 31, so as to adjust the flow direction and flow rate of the waste acid. For example, control module 7 sets the threshold range of fluoride ions in fluoride-containing wastewater to be less than or equal to 10 mg / L, and the pH range of the neutralized effluent in neutralization tank 31 to be 6.5~7.5. If detection module 5 detects a fluoride ion concentration of 25 mg / L and a pH of 7 in the neutralized effluent, then control module 7 controls first valve 61 to increase the flow rate of waste acid into reaction tank 21, and simultaneously controls first dosing device 211 to increase the flow rate of alkaline solution added to reaction tank 21, thereby increasing the calcium ion dosage, strengthening the calcium fluoride precipitation reaction, and reducing the fluoride ion concentration. If a fluoride ion concentration of 8 mg / L is detected and the pH of the neutralized effluent is 7.8, then control module 7 controls first valve 61 to increase the flow rate of waste acid into neutralization tank 31 to neutralize the excess alkali content in neutralization tank 31.

[0070] The second valve 62 is located at the outlet of the waste alkali collection tank 12. The control module 7 controls the second valve 62 according to the pH value of the neutralized effluent in the neutralization tank 31 and the pH value of the non-fluoride-containing wastewater in the pH adjustment tank 41 to adjust the flow direction and flow rate of the waste alkali. The third valve 63 is located at the outlet of the emergency acid storage tank 42. The control module 7 controls the third valve 63 according to the pH value of the non-fluoride-containing wastewater in the pH adjustment tank 41 to adjust the flow rate of the acidic solution.

[0071] For example, control module 7 sets the pH range of the neutralized effluent to be preferably 6.5~7.5, and the pH range of the non-fluoride wastewater to be preferably 6.0~8.0. If detection module 5 detects that the pH of the neutralized effluent is 6.3 and the pH of the non-fluoride wastewater is 6.5, then control module 7 controls the second valve 62 to increase the flow rate of waste alkali into neutralization tank 31. If the pH of the neutralized effluent is detected to be 7.3 and the pH of the non-fluoride wastewater is 5.5, then control module 7 controls the second valve 62 to increase the flow rate of waste alkali into pH adjustment tank 41 to neutralize the excess acid content in pH adjustment tank 41. If the pH of the neutralized effluent is detected to be 7.3 and the pH of the non-fluoride wastewater is 8.2, then control module 7 controls the third valve 63 to open, allowing the acidic solution in emergency acid storage tank 42 to be introduced into pH adjustment tank 41 to neutralize the excess alkali content in pH adjustment tank 41.

[0072] The first valve 61, the second valve 62, and the third valve 63 can be one or more combinations of electric PTFE-lined ball valves, electric PTFE-lined gate valves, corrosion-resistant electric solenoid valves, or other suitable valve types to achieve precise control of the flow rate and direction of waste acid and alkali, as well as flow control of emergency acidic solutions. Specifically, the type and structure of the first valve 61, the second valve 62, and the third valve 63 can be set according to the actual situation, and no specific limitation is made here.

[0073] In this embodiment, sedimentation tank 23, buffer tank 32, and pH adjustment tank 41 are all connected to the integrated wastewater treatment system 03. The supernatant in sedimentation tank 23, the neutralized effluent in buffer tank 32, and the non-fluoride-containing wastewater adjusted to neutral in pH adjustment tank 41 are all transported to the integrated wastewater treatment system 03 for downstream treatment and discharged after meeting water quality standards. The downstream treatment in the integrated wastewater treatment system 03 mainly includes pH fine-tuning, solid-liquid sedimentation separation, online monitoring of water quality indicators, and sludge thickening and dewatering.

[0074] Example 2

[0075] This embodiment provides a method for recycling waste acid and waste alkali, referring to... Figure 2 The waste acid and waste alkali recycling method provided in this embodiment includes the following steps:

[0076] First, a waste acid and waste alkali recycling system is provided. Specifically, any waste acid and waste alkali recycling system from Example 1 can be selected, and its structure and related settings have been described in Example 1, so they will not be repeated here.

[0077] Next, the waste acid generated from the failed acid washing cation bed 01 is collected into the waste acid collection tank 11, the waste alkali generated from the failed alkaline washing anion bed 02 is collected into the waste alkali collection tank 12, the fluoride-containing wastewater generated from the fluoride-containing wastewater production unit 04 is collected into the fluoride-containing wastewater collection tank 22, and the non-fluoride-containing wastewater generated from the non-fluoride-containing wastewater production unit 05 is collected into the pH adjustment tank 41.

[0078] Next, a portion of the waste acid is transported to reaction tank 21, where an alkaline solution is added to react the waste acid with the alkaline solution to generate calcium hydroxide. Specifically, based on the fluoride ion content in fluoride-containing wastewater collection tank 22, the required calcium hydroxide content is calculated, thereby inversely calculating the amounts of waste acid and alkaline solution to be transported to reaction tank 21.

[0079] Next, the calcium hydroxide generated in reaction tank 21 is added to fluoride wastewater collection tank 22 so that the fluoride ions in the fluoride wastewater react with the calcium hydroxide to form calcium fluoride precipitate, and the calcium fluoride precipitate is separated from the supernatant by sedimentation tank 23, thereby removing the fluoride ions in the fluoride wastewater.

[0080] The fluoride-containing wastewater generated by the fluoride wastewater production unit is collected and stored in the fluoride wastewater collection tank 22. The fluoride wastewater is mostly acidic, but calcium hydroxide has high solubility in an acidic environment, making it difficult to quickly form calcium fluoride precipitate. Therefore, in this embodiment, calcium hydroxide plays two roles. First, as a strong alkali, calcium hydroxide can directly neutralize the hydrogen ions in the acidic fluoride wastewater, adjusting the pH value of the fluoride wastewater to the neutral range. After the fluoride wastewater is neutralized, the calcium ions released from calcium hydroxide react directly with the fluoride ions in the fluoride wastewater to form calcium fluoride precipitate. This design can ensure that fluoride ions and calcium ions fully react to form calcium fluoride precipitate, thereby improving the fluoride removal efficiency.

[0081] In this embodiment, the calcium fluoride precipitate in the sedimentation tank 23 is discharged through the sludge discharge port at the bottom of the sedimentation tank 23. The supernatant in the sedimentation tank 23 is transported to the integrated wastewater treatment system 03 for pH fine-tuning, solid-liquid sedimentation separation, online monitoring of water quality indicators, and sludge thickening and dewatering treatment. After the water quality is tested and found to be qualified, it is discharged in compliance with standards.

[0082] Next, some waste acid and waste alkali are transported to neutralization tank 31, where they undergo a neutralization reaction to generate neutralized effluent. After the pH value of the neutralized effluent is tested and found to be qualified, it is transported to buffer tank 32 to homogenize the water quality and buffer the water volume. Subsequently, the neutralized effluent is transported to integrated wastewater treatment system 03 for pH fine-tuning, solid-liquid sedimentation separation, online monitoring of water quality indicators, and sludge thickening and dewatering treatment. After the water quality is tested and found to be qualified, it is discharged in compliance with standards.

[0083] Next, some of the waste alkali is transported to pH adjustment tank 41 to neutralize the acidity of the non-fluoride wastewater. It should be noted that, under normal circumstances, non-fluoride wastewater is slightly acidic. Adding an appropriate amount of waste alkali according to the detection value of the third pH meter 57 is sufficient to adjust the non-fluoride wastewater to neutral and meet the standard. However, if too much waste alkali is added or highly alkaline wastewater is mixed in, the pH can easily exceed the standard and become too high. Therefore, this embodiment also includes an emergency acid storage tank 42 to store acidic solution, which is added to pH adjustment tank 41 when the non-fluoride wastewater is alkaline to adjust the non-fluoride wastewater to neutral.

[0084] In this embodiment, the waste acid in the waste acid collection tank 11 is preferentially transported to the reaction tank 21 to prepare calcium hydroxide, and the remaining waste acid is transported to the neutralization tank 31 for neutralization reaction; the waste alkali in the waste alkali collection tank 12 is preferably transported to the neutralization tank 31 for neutralization reaction, and the remaining waste alkali is transported to the pH adjustment tank 41.

[0085] The acidic solution in the emergency acid storage tank 42 can be any of dilute hydrochloric acid, dilute sulfuric acid, or other suitable acidic solutions, used for rapid neutralization of slightly alkaline non-fluoride-containing wastewater to meet emergency pH adjustment needs. Preferably, the acidic solution in the emergency acid storage tank 42 is dilute hydrochloric acid, which has a fast neutralization speed, low cost, and minimal secondary pollution of water quality, and can efficiently complete the emergency pH adjustment operation for slightly alkaline non-fluoride-containing wastewater.

[0086] In this embodiment, the non-fluoride wastewater adjusted to the neutral range in the pH adjustment tank 41 is finally transported to the integrated wastewater treatment system 03 for pH fine-tuning, solid-liquid sedimentation separation, online monitoring of water quality indicators, and sludge thickening and dewatering treatment, and is discharged in compliance with standards after passing the water quality test.

[0087] The above description is only a partial preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A waste acid and waste alkali recycling system, applied to a pure water preparation system, wherein the pure water preparation system is equipped with a cation bed and an anion bed, characterized in that, It includes a waste liquid collection module, a fluoride-containing wastewater treatment module, an acid-base neutralization module, and a non-fluoride-containing wastewater treatment module; The waste liquid collection module includes a waste acid collection tank and a waste alkali collection tank. The waste acid collection tank is connected to the cation bed and is used to collect and store the waste acid generated by the acid washing failure of the cation bed. The waste alkali collection tank is connected to the anion bed and is used to collect and store the waste alkali generated by the alkali washing failure of the anion bed. The fluoride-containing wastewater treatment module includes a reaction tank, a fluoride-containing wastewater collection tank, and a sedimentation tank. The reaction tank is connected to the waste acid collection tank so that the waste acid is transported to the reaction tank and reacts with an alkaline solution to generate calcium hydroxide. The fluoride-containing wastewater collection tank is connected to the reaction tank so that the calcium hydroxide is transported to the fluoride-containing wastewater collection tank and reacts with fluoride ions in the fluoride-containing wastewater to generate calcium fluoride precipitate. The sedimentation tank is connected to the fluoride-containing wastewater collection tank to separate the calcium fluoride precipitate from the supernatant. The acid-base neutralization module includes a neutralization tank and a buffer tank. The neutralization tank is connected to the waste acid collection tank and the waste alkali collection tank so that the waste acid and the waste alkali are transported to the neutralization tank and undergo an acid-base neutralization reaction to generate neutralized effluent. The buffer tank is connected to the neutralization tank and is used to homogenize the water quality and buffer the water volume of the neutralized effluent. The non-fluoride wastewater treatment module includes a pH adjustment tank, which is connected to the waste alkali collection tank so that the waste alkali is transported to the pH adjustment tank and neutralizes the acidity of the non-fluoride wastewater.

2. The waste acid and waste alkali recycling system according to claim 1, characterized in that, The sedimentation tank, the buffer tank, and the pH adjustment tank are all connected to the integrated wastewater treatment system for post-treatment of the supernatant in the sedimentation tank, the neutralized effluent in the buffer tank, and the non-fluoride-containing wastewater adjusted to neutral in the pH adjustment tank, and discharge the wastewater after it meets the water quality standards.

3. The waste acid and waste alkali recycling system according to claim 1, characterized in that, The reaction tank is equipped with a first dosing device for adding an alkaline solution to the reaction tank.

4. The waste acid and waste alkali recycling system according to claim 3, characterized in that, The non-fluoride wastewater treatment module also includes an emergency acid storage tank for storing acidic solutions. The emergency acid storage tank is connected to the pH adjustment tank and is used to add acidic solutions to the pH adjustment tank when the non-fluoride wastewater is alkaline, so as to adjust the non-fluoride wastewater to neutral.

5. The waste acid and waste alkali recycling system according to claim 4, characterized in that, The waste acid and alkali recycling system also includes a detection module, a flow regulation module, and a control module. The control module receives the detection signal from the detection module and controls the flow regulation module, the first dosing device, and the emergency acid storage tank according to the detection signal.

6. The waste acid and waste alkali recycling system according to claim 5, characterized in that, The detection module includes a first flow meter, a second flow meter, a calcium ion concentration analyzer, a fluoride ion concentration analyzer, a first pH meter, a second pH meter, and a third pH meter; The first flow meter and the calcium ion concentration analyzer are installed at the inlet of the reaction tank to detect the calcium ion content in the reaction tank. The second flow meter and the fluoride ion concentration analyzer are installed at the inlet of the fluoride-containing wastewater collection tank to detect the fluoride ion content in the fluoride-containing wastewater collection tank. The first pH meter is installed in the fluoride-containing wastewater collection tank to detect the pH value of the fluoride-containing wastewater; The second pH meter is installed in the neutralization tank to detect the pH value of the neutralized effluent; The third pH meter is installed in the pH adjustment tank and is used to detect the pH value of the non-fluoride wastewater.

7. The waste acid and waste alkali recycling system according to claim 6, characterized in that, The flow control module includes a first valve, a second valve, and a third valve; The first valve is located at the outlet of the waste acid collection tank. The control module controls the first valve according to the pH value of the fluoride-containing wastewater, the fluoride ion content, and the pH value of the neutralized effluent in the neutralization tank, so as to adjust the flow direction and flow rate of the waste acid. The second valve is located at the outlet of the waste alkali collection tank. The control module controls the second valve according to the pH value of the neutralized effluent in the neutralization tank and the pH value of the non-fluoride wastewater in the pH adjustment tank, so as to adjust the flow direction and flow rate of the waste alkali. The third valve is located at the outlet of the emergency acid storage tank. The control module controls the third valve according to the pH value of the non-fluoride wastewater in the pH adjustment tank to adjust the flow rate of the acidic solution.

8. A method for recycling waste acid and alkali, characterized in that, Includes the following steps: Provide waste acid and alkali recycling systems; Waste acid generated from the failed pickling of the cation exchange bed is collected in the waste acid collection tank; waste alkali generated from the failed alkaline washing of the anion exchange bed is collected in the waste alkali collection tank; fluoride-containing wastewater is collected in the fluoride-containing wastewater collection tank; and non-fluoride-containing wastewater is collected in the pH adjustment tank. A portion of the waste acid is transported to a reaction tank, and an alkaline solution is added to react the waste acid with the alkaline solution to generate calcium hydroxide. The calcium hydroxide is added to the fluoride-containing wastewater collection tank so that the fluoride ions in the fluoride-containing wastewater react with the calcium hydroxide to form calcium fluoride precipitate. The calcium fluoride precipitate is then separated from the supernatant in a sedimentation tank, thereby removing the fluoride ions from the fluoride-containing wastewater. A portion of the waste acid and waste alkali are transported to a neutralization tank, where they undergo a neutralization reaction to generate neutralized effluent. The neutralized effluent is then transported to a buffer tank to homogenize the water quality and buffer the water volume. A portion of the waste alkali is transported to the pH adjustment tank to neutralize the acidity of the non-fluoride wastewater.

9. The method for recycling waste acid and alkali according to claim 8, characterized in that, Based on the fluoride ion content in the fluoride-containing wastewater collection tank, the required calcium hydroxide content is calculated, thereby determining the content of waste acid and alkaline solution to be transported to the reaction tank.

10. The method for recycling waste acid and alkali according to claim 8, characterized in that, The waste acid in the waste acid collection tank is preferentially transported to the reaction tank to prepare calcium hydroxide, and the remaining waste acid is transported to the neutralization tank for neutralization reaction; the waste alkali in the waste alkali collection tank is preferably transported to the neutralization tank for neutralization reaction, and the remaining waste alkali is transported to the pH adjustment tank.

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