A treatment process for perchlorate wastewater

Abstract

This invention discloses a treatment process for perchlorate wastewater, the steps of which are as follows: (1) Add an appropriate amount of coagulant to the perchlorate wastewater to be treated for coagulation reaction until no more precipitation is produced, and then add an appropriate amount of coagulant aid to the reaction system. After solid-liquid separation, a first supernatant and perchlorate precipitate are obtained; (2) Add an appropriate amount of iron salt and excess oxidant to the first supernatant in sequence for oxidation reaction for at least 30 minutes, and then add a pH adjuster to adjust the pH value of the reaction system to 7-10 until no more precipitation is produced. Then add an appropriate amount of polyacrylamide to the reaction system, and then perform a second solid-liquid separation to obtain a second supernatant and iron salt precipitate; (3) Filter the second supernatant through an activated carbon filter for a period of time for deep removal. After reaching the standard, the treatment of perchlorate wastewater is completed.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment, specifically relating to a treatment process for perchlorate wastewater. Background Technology

[0002] Perchlorates are widely used in aerospace, military, industrial production, fireworks manufacturing and other fields due to their strong oxidizing properties and high stability.

[0003] While making outstanding contributions, perchlorate pollution has become increasingly serious. Perchlorate is characterized by high solubility, poor adsorption, high mobility, and low degradation, directly affecting the safety of surface water and groundwater drinking water, posing a serious threat to ecosystems and human health. As a novel anionic trace pollutant, perchlorate can disrupt normal thyroid function and affect human metabolism and development.

[0004] Perchlorate is widely used and in high demand in my country, especially in the fields of fireworks production and aerospace. Every year, a large amount of high-concentration perchlorate wastewater is generated, posing a serious challenge to water quality safety.

[0005] In March 2022, the National Health Commission issued the "Standards for Drinking Water Quality" (GB 5749-2022), which added a perchlorate standard limit of 0.07 mg / L, and the supervision and treatment of related perchlorate pollutant emissions are also being continuously strengthened.

[0006] Currently, the most commonly used methods for treating perchlorate wastewater include chemical reduction, biodegradation, and physical adsorption.

[0007] Chemical reduction is a method for treating perchlorate wastewater by reducing perchlorate ions to harmless chloride ions via a redox reaction. However, the stable chemical structure and high reactivity of perchlorate ions result in a slow reduction process. While catalysts can effectively shorten the reaction time, the redox reaction conditions are relatively demanding, precious metal catalysts are expensive, and there is also the risk of secondary pollution. Currently, chemical reduction remains in the experimental stage and has not yet been implemented industrially.

[0008] Biodegradation is a widely used method for treating perchlorate wastewater. It utilizes microorganisms to degrade perchlorate ions into non-toxic chloride ions, offering advantages such as low cost, high efficiency, and minimal removal of byproducts. However, biodegradation also has drawbacks: slow onset of action, demanding reduction conditions, and the potential for pathogenic microorganisms, making its practical application challenging.

[0009] Physical adsorption methods (activated carbon adsorption, ion exchange, membrane exchange technology) are simple, fast and efficient for treating perchlorate wastewater, but their regeneration costs are high and they also generate a large amount of highly concentrated perchlorate wastewater that needs further treatment, which limits their large-scale application.

[0010] In recent years, there have been few reports on the method of separating perchlorate by coagulation sedimentation. The main reason is that perchlorate is highly soluble in water and organic solvents, making it difficult to flocculate with ordinary cationic coagulants. Furthermore, excessive addition of coagulants can affect the subsequent water quality. Summary of the Invention

[0011] Purpose of the invention: In view of the shortcomings of the prior art, the present invention discloses a perchlorate wastewater treatment process that can remove perchlorate from industrial wastewater in a low-cost, high-efficiency and rapid manner.

[0012] Technical principle of the invention: First, taking advantage of the anionic nature of perchlorate, a coagulant with cationic surfactants is added to the perchlorate wastewater. The coagulant combines with perchlorate ions to form a stable precipitate, thus initially separating the perchlorate in the water to obtain a supernatant and a perchlorate precipitate. Secondly, the first supernatant is further oxidized to obtain a second supernatant and an iron salt precipitate. Finally, the supernatant from the second stage is treated by adsorption using an activated carbon adsorbent. Once the standard is met, the treatment of perchlorate wastewater is complete. Perchlorate precipitates and iron salt precipitates can be directly transported to a solid waste treatment plant for centralized processing.

[0013] Technical solution: A treatment process for perchlorate wastewater, the specific steps of which are as follows: (1) Add an appropriate amount of coagulant to the perchlorate wastewater to be treated and carry out coagulation reaction until no more precipitation is produced. Then add an appropriate amount of coagulant aid to the reaction system. After solid-liquid separation, a supernatant and perchlorate precipitate are obtained. (2) Add an appropriate amount of iron salt and an excess of oxidant to the first supernatant in sequence and carry out the oxidation reaction for at least 30 min, preferably 30 to 60 min. Then add a pH adjuster to adjust the pH value of the reaction system to 7 to 10 until no more precipitation is produced. Then add an appropriate amount of polyacrylamide to the reaction system and then carry out a second solid-liquid separation to obtain the second supernatant and iron salt precipitate. (3) The supernatant of the two stages is adsorbed and filtered through an activated carbon filter for a period of time to remove the perchlorate. Once the standard is met, the treatment of perchlorate wastewater is completed.

[0014] Furthermore, in step (1), the concentration of perchlorate is 30 mg / L to 1000 mg / L, based on the total mass of the perchlorate wastewater to be treated.

[0015] Further, the coagulant in step (1) is a cationic surfactant, preferably an ammonium-based cationic surfactant, and more preferably one or more of dodecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride. The coagulant can combine with perchlorate ions to form a stable perchlorate precipitate, thereby achieving the purpose of rapidly separating perchlorate from wastewater. In the specific implementation of this invention, after adding an excess of coagulant to the perchlorate wastewater to be treated, a white milky turbidity immediately appears. With slow stirring, it gradually transforms into a solution with white strip-shaped flocculent matter.

[0016] Furthermore, the amount of cations in the coagulant added in step (1) is no more than 1.5 times the molar amount of perchlorate in the perchlorate wastewater to be treated, preferably 1.1 to 1.3 times, and / or Stirring is required during the reaction in step (1), with a stirring speed of at least 100 r / min, preferably 100 r / min to 200 r / min, and / or The reaction time for the coagulation reaction in step (1) is at least 3 minutes, preferably 3 to 10 minutes.

[0017] Furthermore, in step (1), solid-liquid separation is achieved by a centrifuge or a filter press, preferably by a plate and frame filter press, and / or The coagulant aid mentioned in step (1) is one or more of bentonite, diatomite, and perlite, preferably bentonite, and / or Based on the volume of the perchlorate wastewater to be treated in step (1), the amount of coagulant added in step (1) is 1 to 2 g / L.

[0018] Further, the iron salt mentioned in step (2) is selected from one or more of ferric chloride, ferrous sulfate, ferric sulfate, and polyferric sulfate, preferably ferrous sulfate, and / or After adding an appropriate amount of iron salt to the supernatant in step (2), the total concentration of ferric ions and / or ferrous ions in the supernatant is 0.1–0.3 g / L. The role of the iron salt in step (2) is to reduce the chemical oxygen demand (COD) in the supernatant.

[0019] Further, the oxidant mentioned in step (2) is one of air, oxygen, hydrogen peroxide and ozone.

[0020] Further, during the oxidation reaction in step (2), stirring is continuously carried out, and the stirring speed is at least 100 r / min, preferably 100 r / min to 200 r / min.

[0021] Further, the pH regulator in step (2) is one or more of calcium oxide, calcium hydroxide, sodium oxide, and sodium hydroxide.

[0022] Further, based on the volume of the perchlorate wastewater to be treated in step (1), the addition amount of polyacrylamide in step (2) is 0.1 to 0.5 mg / L, and / or In step (2), secondary solid-liquid separation is achieved by a centrifuge or a filter press or a thickener, and preferably, secondary solid-liquid separation is achieved by a thickener.

[0023] Further, the filling material in the activated carbon filter in step (3) is modified activated carbon, and / or The secondary supernatant in step (3) is adsorbed and filtered by the activated carbon filter for at least 2 minutes, preferably 2 to 10 minutes.

[0024] Beneficial effects: A perchlorate wastewater treatment process disclosed by the present invention has the following beneficial effects: (1) Using the chemical precipitation method to quickly separate perchlorate, while stably removing perchlorate pollutants in water, greatly shortening the wastewater treatment time; combined with activated carbon adsorption for deep purification, it also has good treatment effects on sulfides, COD, and ammonia nitrogen in the wastewater. In the final effluent, the concentration of perchlorate anion ≤ 0.7 mg / L, and the removal rate of perchlorate anion is as high as 99.9%; (2) Perchlorate is removed from water in the form of a precipitate, with a small amount of slag, stable performance, insoluble in water and acid, low toxicity, and easy to store; (3) The chemicals used are cheap and easily available, and the equipment used is all conventional devices. The process is simple, safe and efficient, with low energy consumption and low cost, and is easy to be industrially promoted. Brief Description of the Drawings

[0025] Figure 1 It is a flow chart of a perchlorate wastewater treatment process disclosed by the present invention.

[0026] [[ID=3l]] Figure 2 It is a schematic diagram of a water treatment device applicable to a perchlorate wastewater treatment process disclosed by the present invention. Among them: Detailed Description of the Specific Embodiments

[0027] The following is a detailed description of the specific embodiments of the present invention.

[0028] The "range" disclosed in this invention is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10–50 is listed for a specific parameter, it is also expected that ranges of 10–40 and 20–50 are also included. Furthermore, if the minimum range values ​​are 1 and 2, and the maximum range values ​​are 3, 4, and 5, then the following ranges are all expected: 1–3, 1–4, 1–5, 2–3, 2–4, and 2–5. In this application, unless otherwise stated, the numerical range "a–b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0–5" means that all real numbers between "0–5" have been listed herein; "0–5" is merely a shortened representation of these numerical combinations.

[0029] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0030] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0031] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0032] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0033] Unless otherwise specified, the reaction will proceed under normal temperature and pressure conditions.

[0034] Unless otherwise specified, all parts or percentages are by weight or by weight percentage.

[0035] In this invention, all the substances used are known substances that can be purchased or synthesized by known methods.

[0036] In this invention, all the devices or equipment used are conventional devices or equipment known in the art and are readily available.

[0037] Unless otherwise specified, the standard referred to in this application is the "Discharge Standard of Industrial Wastewater Perchlorate Pollutants" (DB43 / 3001—2024) of Hunan Province. Example 1 The perchlorate wastewater to be treated comes from the wastewater reused in the workshop of a fireworks factory in Liuyang City, Hunan Province, and its perchlorate concentration is 750 mg / L.

[0038] A treatment process for perchlorate wastewater, the specific steps of which are as follows: (1) Add 2.64 g cetyltrimethylammonium chloride (CTAC) to 1000 mL of the above perchlorate wastewater to be treated, stir at 200 r / min for 5 min, observe that no more precipitate is formed in the reaction system, then add 1.2 g bentonite, and obtain a supernatant and perchlorate precipitate by solid-liquid separation through plate and frame filter press; (2) Add an appropriate amount of ferrous sulfate to the supernatant obtained in step (1) so that the concentration of ferrous ions in the reaction system is 0.1 g / L. Slowly add 0.75 mL of hydrogen peroxide (30% V / V) and react at a rate of 100 r / min for 30 min. Control the pH value to 8 with calcium oxide until no more precipitate is produced. Add 0.1 mg of PAM and use a thickener to achieve secondary solid-liquid separation to obtain the second supernatant and iron salt precipitate. (3) The supernatant of the second stage is filtered through an activated carbon filter for 5 minutes, and the resulting filtrate is the final effluent.

[0039] Product Analysis: 1. Water quality analysis was performed on the raw water, the first stage supernatant, the second stage supernatant, and the filtrate. The specific results are shown in Table 1. As can be seen from the results in Table 1, the method used in this embodiment to treat perchlorate wastewater achieves a perchlorate removal rate of up to 99.99%, and the resulting waste liquid (filtrate) meets the "Discharge Standard of Industrial Wastewater Perchlorate Pollutants" (DB43 / 3001—2024) of Hunan Province.

[0040] 2. The perchlorate precipitate obtained in step (1) was subjected to a toxicity leaching test, and the results are shown in Table 2. As can be seen from the results in Table 2, the perchlorate precipitate produced in this embodiment has low toxicity, is insoluble in acidic water, and is easy to store. Therefore, the perchlorate precipitate and iron salt precipitate can be directly transported to a solid waste treatment plant for centralized treatment.

[0041] This invention discloses a process for treating perchlorate wastewater, which requires corresponding supporting water treatment equipment. Any water treatment equipment capable of implementing the above technical solution can be used, such as the water treatment equipment described below.

[0042] like Figure 2 As shown, a perchlorate wastewater treatment device comprises a coagulation and sedimentation unit, an oxidation reaction unit, and a deep adsorption unit connected in sequence, wherein: The coagulation and sedimentation unit consists of the following components: First delivery pump 11; The coagulation reaction tank 1 has its outlet connected to the inlet of the coagulation reaction tank 1 via a pipe, and its outlet connected to the inlet of the coagulation reaction tank 1 via a first pipe. The first pipe is equipped with a first metering pump 161. The outlet of the coagulation reaction tank 1 is connected to the inlet of the buffer tank 12 through a second pipe, and the outlet of the second reagent dosing device 17 is connected to the second pipe through a third pipe. A second metering pump 171 is provided in the third pipe. The filter press 14, wherein the outlet of the buffer tank 12 is connected to the inlet of the filter press 14 via a fourth pipe; The oxidation reaction unit consists of the following components: The oxidation reaction tank 2 is connected to the inlet of the oxidation reaction tank 2 via a fifth pipe, the outlet of the filter press 14 is connected to the inlet of the oxidation reaction tank 2 via a sixth pipe, and a third metering pump 251 is installed in the sixth pipe. The fourth metering pump 26 is connected to the inlet of the oxidation reaction tank 2 via a seventh pipe, and a fourth metering pump 261 is installed in the seventh pipe. The neutralization sedimentation tank 22 is connected to the inlet of the neutralization sedimentation tank 22 via a pipe. The fifth reagent dosing device 27 is connected to the inlet of the neutralization sedimentation tank 22 via an eighth pipe. The eighth pipe is equipped with a fifth metering pump 271. The thickener 23 has its outlet connected to the inlet of the thickener 23 via a ninth pipe, and its outlet connected to the ninth pipe via a tenth pipe. A sixth metering pump 281 is installed in the tenth pipe. A bottom discharge valve is installed at the bottom of the thickener 23, and the bottom discharge valve is connected to the inlet of the filter press 14 via a slurry discharge pipe. The deep adsorption unit includes an activated carbon filter 3, and a thickener 23 is provided with an overflow port. The liquid outlet (overflow port) of the upper layer of the thickener 23 is connected to the liquid inlet of the activated carbon filter 3 through an eleventh pipe.

[0043] The upper outlet of the thickener 23 is connected to the inlet of the activated carbon filter 3.

[0044] Furthermore, a second delivery pump 13 is provided in the fourth pipeline. The second delivery pump 13 supplies material to the filter press 14.

[0045] Furthermore, the filter press 14 is a plate and frame filter press.

[0046] Furthermore, the fifth pipeline is sequentially equipped with a first filtrate buffer tank 15 and a third transfer pump 21 along the liquid flow direction. The first filtrate buffer tank 15 is used for temporary storage of the filtrate separated by the filter press 14. The third transfer pump 21 is used to supply material to the oxidation reaction tank 2.

[0047] Furthermore, the eleventh pipeline is sequentially equipped with a second filtrate buffer tank 24 and a fourth delivery pump 31 along the liquid flow direction. The second filtrate buffer tank 24 is used for temporary storage of the filtrate separated by the thickener 23. The fourth delivery pump 31 is used to supply material to the activated carbon filter 3.

[0048] Furthermore, the deep adsorption unit also includes an outlet water tank 32, and the outlet of the activated carbon filter 3 is connected to the inlet of the outlet water tank 32.

[0049] Furthermore, the coagulation reaction tank 1, the buffer tank 12, the oxidation reaction tank 2, and the neutralization sedimentation tank 22 are all equipped with stirring devices.

[0050] Furthermore, the oxidation reaction tank 2 and the neutralization precipitation tank 22 are respectively equipped with a level gauge, a pH meter and an ORP meter.

[0051] Furthermore, the first drug dosing device 16, the second drug dosing device 17, the third drug dosing device 25, the fourth drug dosing device 26, the fifth drug dosing device 27, and the sixth drug dosing device 28 are each equipped with a stirrer and a level gauge.

[0052] The delivery pipelines of the first dosing device 16, the second dosing device 17, the third dosing device 25, the fourth dosing device 26, the fifth dosing device 27, and the sixth dosing device 28 are respectively equipped with a first metering pump 161, a second metering pump 171, a third metering pump 251, a fourth metering pump 261, a fifth metering pump 271, and a sixth metering pump 281, which are used to control the dosage and addition rate of the reagent.

[0053] The following is a further detailed description of the implementation process of this utility model: Wastewater containing perchlorate enters the coagulation sedimentation tank 1 via the first transfer pump 11. After coagulation reaction, it overflows into the buffer tank 12, and then enters the filter press 14 via the second transfer pump 13. The separated filtrate enters the first filtrate buffer tank 15 for temporary storage, and then enters the oxidation reaction tank 2 and the neutralization sedimentation tank 22 in sequence via the third transfer pump 21 to complete the oxidation reaction. After separation by the thickener 23, the filtrate enters the second filtrate buffer tank 24 for temporary storage, and then enters the activated carbon filter 3 via the fourth transfer pump 31 for deep purification. The purified filtrate is the final effluent and enters the effluent tank 32 for temporary storage.

[0054] The first reagent dosing device 16, the second reagent dosing device 17, the third reagent dosing device 25, the fourth reagent dosing device 26, the fifth reagent dosing device 27, and the sixth reagent dosing device 28 are each equipped with a stirrer and a level gauge. After the reagents are prepared according to the requirements, they are sent to the corresponding reaction tanks by the first metering pump 161, the second metering pump 171, the third metering pump 251, the fourth metering pump 261, the fifth metering pump 271, and the sixth metering pump 281, respectively.

[0055] Example 2 The perchlorate wastewater to be treated comes from the wastewater reused in the workshop of a fireworks factory in Liuyang City, Hunan Province, and its perchlorate concentration is 30 mg / L.

[0056] A treatment process for perchlorate wastewater, the specific steps of which are as follows: (1) Add an appropriate amount of coagulant to the perchlorate wastewater to be treated and carry out coagulation reaction until no more precipitation is produced. Then add an appropriate amount of coagulant aid to the reaction system. After solid-liquid separation, a supernatant and perchlorate precipitate are obtained. (2) Add appropriate amount of iron salt and excess oxidant to the first supernatant in sequence and carry out oxidation reaction for 30 min. Then add pH adjuster to adjust the pH value of the reaction system to 7 until no more precipitation is produced. Then add appropriate amount of polyacrylamide (PAM) to the reaction system and carry out secondary solid-liquid separation to obtain the second supernatant and iron salt precipitate. (3) The supernatant of the two stages is adsorbed and filtered through an activated carbon filter for a period of time to remove the perchlorate. Once the standard is met, the treatment of perchlorate wastewater is completed.

[0057] Furthermore, in step (1), the perchlorate content is 30 mg / L, based on the total mass of the perchlorate wastewater to be treated.

[0058] Further, the coagulant mentioned in step (1) is dodecyltrimethylammonium chloride.

[0059] Furthermore, in step (1), the amount of cations in the coagulant added is 1.1 times the molar amount of perchlorate in the perchlorate wastewater to be treated, and / or Stirring is required during the reaction in step (1) at a speed of 100 r / min, and / or The reaction time for the coagulation reaction in step (1) is 10 minutes.

[0060] Furthermore, in step (1), solid-liquid separation is achieved using a centrifuge, and / or The coagulant diatomaceous earth mentioned in step (1), and / or Based on the volume of the perchlorate wastewater to be treated in step (1), the amount of coagulant added in step (1) is 1 g / L.

[0061] Further, the iron salt mentioned in step (2) is ferric chloride, and / or In step (2), after adding an appropriate amount of iron salt to the supernatant, the total concentration of iron ions in the supernatant is 0.1 g / L.

[0062] Furthermore, the oxidant in step (2) is air.

[0063] Furthermore, during the oxidation reaction described in step (2), stirring is continuously performed at a speed of 100 r / min.

[0064] Furthermore, the pH adjuster mentioned in step (2) is calcium oxide.

[0065] Further, based on the volume of the perchlorate wastewater to be treated in step (1), the amount of polyacrylamide added in step (2) is 0.1 mg / L, and / or In step (2), secondary solid-liquid separation is achieved by centrifuge, preferably by thickener.

[0066] Further, the filling material in the activated carbon filter described in step (3) is modified activated carbon, and / or The supernatant from step (3) is filtered by an activated carbon filter for 2 minutes.

[0067] Product Analysis: 1. Water quality analysis was performed on the raw water, the first stage supernatant, the second stage supernatant, and the filtrate. The specific results are shown in Table 3. As can be seen from the results in Table 3, the method used in this embodiment to treat perchlorate wastewater has a high perchlorate removal rate, and the resulting waste liquid (filtrate) meets the "Discharge Standard of Industrial Wastewater Perchlorate Pollutants" (DB43 / 3001—2024) of Hunan Province.

[0068] 2. The perchlorate precipitate obtained in step (1) was subjected to a toxicity leaching test, and the results are shown in Table 4. As can be seen from the results in Table 4, the perchlorate precipitate produced in this embodiment has low toxicity, is insoluble in acidic water, and is easy to store. Therefore, the perchlorate precipitate and iron salt precipitate can be directly transported to a solid waste treatment plant for centralized treatment.

[0069] Example 3 The perchlorate wastewater to be treated comes from the wastewater reused in the workshop of a fireworks factory in Yiyang City, Hunan Province, and its perchlorate concentration is 990 mg / L.

[0070] A treatment process for perchlorate wastewater, the specific steps of which are as follows: (1) Add an appropriate amount of coagulant to the perchlorate wastewater to be treated and carry out coagulation reaction until no more precipitation is produced. Then add an appropriate amount of coagulant aid to the reaction system. After solid-liquid separation, a supernatant and perchlorate precipitate are obtained. (2) Add appropriate amount of iron salt and excess oxidant to the first supernatant in sequence for oxidation reaction for 60 min, then add pH adjuster to adjust the pH value of the reaction system to 10 until no more precipitation is produced, then add appropriate amount of polyacrylamide (PAM) to the reaction system, and then perform secondary solid-liquid separation to obtain the second supernatant and iron salt precipitate. (3) The supernatant of the two stages is adsorbed and filtered through an activated carbon filter for a period of time to remove the perchlorate. Once the standard is met, the treatment of perchlorate wastewater is completed.

[0071] Furthermore, in step (1), the perchlorate content is 990 mg / L, based on the total mass of the perchlorate wastewater to be treated.

[0072] Further, the coagulant mentioned in step (1) is dodecyl dimethyl benzyl ammonium chloride.

[0073] Furthermore, in step (1), the amount of cations in the coagulant added is 1.3 times the molar amount of perchlorate in the perchlorate wastewater to be treated, and / or Stirring is required during the reaction in step (1) at a speed of 200 r / min, and / or The reaction time for the coagulation reaction in step (1) is 3 minutes.

[0074] Further, in step (1), solid-liquid separation is achieved by using a plate and frame filter press, and / or The coagulant aid mentioned in step (1) is perlite, and / or Based on the volume of the perchlorate wastewater to be treated in step (1), the amount of coagulant added in step (1) is 2 g / L.

[0075] Further, the iron salt mentioned in step (2) is ferric sulfate, and / or In step (2), after adding an appropriate amount of iron salt to the supernatant, the total concentration of iron ions in the supernatant is 0.3 g / L.

[0076] Furthermore, the oxidant in step (2) is ozone.

[0077] Furthermore, during the oxidation reaction described in step (2), stirring is continuously performed at a speed of 200 r / min.

[0078] Furthermore, the pH adjuster mentioned in step (2) is calcium hydroxide.

[0079] Further, based on the volume of the perchlorate wastewater to be treated in step (1), the amount of polyacrylamide added in step (2) is 0.5 mg / L, and / or In step (2), a secondary solid-liquid separation is achieved by using a thickener.

[0080] Further, the filling material in the activated carbon filter described in step (3) is modified activated carbon, and / or The supernatant from step (3) is filtered by an activated carbon filter for 10 minutes.

[0081] Product Analysis: 1. Water quality analysis was performed on the raw water, the first stage supernatant, the second stage supernatant, and the filtrate. The specific results are shown in Table 5. As can be seen from the results in Table 5, the perchlorate removal rate of the perchlorate wastewater treated by the method in this embodiment is as high as 99.99%, and the resulting waste liquid (filtrate) meets the "Discharge Standard of Industrial Wastewater Perchlorate Pollutants" (DB43 / 3001—2024) of Hunan Province.

[0082] 2. The perchlorate precipitate obtained in step (1) was subjected to a toxicity leaching test, and the results are shown in Table 6. Table 6: Toxicity Analysis Table As can be seen from the results in Table 6, the perchlorate precipitate produced in this embodiment has low toxicity, is insoluble in acidic water, and is easy to store. Therefore, the perchlorate precipitate and iron salt precipitate can be directly transported to a solid waste treatment plant for centralized treatment.

[0083] Example 4 The perchlorate wastewater to be treated comes from the wastewater reused in the workshop of a fireworks factory in Yiyang City, Hunan Province, and its perchlorate concentration is 600 mg / L.

[0084] A treatment process for perchlorate wastewater, the specific steps of which are as follows: (1) Add an appropriate amount of coagulant to the perchlorate wastewater to be treated and carry out coagulation reaction until no more precipitation is produced. Then add an appropriate amount of coagulant aid to the reaction system. After solid-liquid separation, a supernatant and perchlorate precipitate are obtained. (2) Add appropriate amount of iron salt and excess oxidant to the first supernatant in sequence and carry out oxidation reaction for 50 min. Then add pH adjuster to adjust the pH value of the reaction system to 8 until no more precipitation is produced. Then add appropriate amount of polyacrylamide (PAM) to the reaction system and carry out secondary solid-liquid separation to obtain the second supernatant and iron salt precipitate. (3) The supernatant of the two stages is adsorbed and filtered through an activated carbon filter for a period of time to remove the perchlorate. Once the standard is met, the treatment of perchlorate wastewater is completed.

[0085] Furthermore, in step (1), the perchlorate content is 600 mg / L, based on the total mass of the perchlorate wastewater to be treated.

[0086] Further, the coagulant in step (1) is octadecyltrimethylammonium chloride. In another embodiment, the coagulant in step (1) is a mixture of dodecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride in equimolar ratio.

[0087] Furthermore, in step (1), the amount of cations in the coagulant added is 1.5 times the molar amount of perchlorate in the perchlorate wastewater to be treated, and / or Step (1) requires stirring during the reaction at a speed of 180 r / min, and / or The reaction time for the coagulation reaction in step (1) is 6 minutes.

[0088] Furthermore, in step (1), solid-liquid separation is achieved using a plate and frame filter press, and / or The coagulant aid mentioned in step (1) is a mixture of bentonite, diatomaceous earth, and perlite in equal mass ratios, and / or Based on the volume of the perchlorate wastewater to be treated in step (1), the amount of coagulant added in step (1) is 1.5 / L.

[0089] Further, the iron salt mentioned in step (2) is polyferric sulfate, and / or In step (2), after adding an appropriate amount of iron salt to the supernatant, the total concentration of iron ions and / or ferrous ions in the supernatant is 0.2 g / L.

[0090] In another embodiment, the iron salt mentioned in step (2) is a mixture of ferric chloride, ferrous sulfate, ferric sulfate, and polyferric sulfate in equal mass ratios, and / or In step (2), after adding an appropriate amount of iron salt to the supernatant, the total concentration of ferric ions and / or ferrous ions in the supernatant is 0.25 g / L.

[0091] Furthermore, the oxidant mentioned in step (2) is oxygen.

[0092] Furthermore, during the oxidation reaction described in step (2), stirring is continuously performed at a speed of 180 r / min.

[0093] Further, the pH adjuster in step (2) is sodium oxide. In another embodiment, the pH adjuster in step (2) is sodium hydroxide. In yet another embodiment, the pH adjuster in step (2) is a mixture of calcium oxide, calcium hydroxide, sodium oxide, and sodium hydroxide in equal mass ratios.

[0094] Further, based on the volume of the perchlorate wastewater to be treated in step (1), the amount of polyacrylamide added in step (2) is 0.3 mg / L, and / or In step (2), a secondary solid-liquid separation is achieved by using a filter press.

[0095] Further, the filling material in the activated carbon filter described in step (3) is modified activated carbon, and / or The supernatant from step (3) is filtered by an activated carbon filter for 5 minutes.

[0096] Product Analysis: 1. Water quality analysis was performed on the raw water, the first stage supernatant, the second stage supernatant, and the filtrate. The specific results are shown in Table 7. As can be seen from the results in Table 7, the perchlorate removal rate of the perchlorate wastewater treated by the method in this embodiment is as high as 99.99%, and the resulting waste liquid (filtrate) meets the "Discharge Standard of Industrial Wastewater Perchlorate Pollutants" (DB43 / 3001—2024) of Hunan Province.

[0097] 2. The perchlorate precipitate obtained in step (1) was subjected to a toxicity leaching test, and the results are shown in Table 8. As can be seen from the results in Table 2, the perchlorate precipitate produced in this embodiment has low toxicity, is insoluble in acidic water, and is easy to store. Therefore, the perchlorate precipitate and iron salt precipitate can be directly transported to a solid waste treatment plant for centralized treatment.

[0098] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention.

Claims

1. A treatment process for perchlorate wastewater, characterized in that, The specific steps are as follows: (1) Add an appropriate amount of coagulant to the perchlorate wastewater to be treated for coagulation reaction until no more precipitation is produced. Then add an appropriate amount of coagulant aid to the reaction system. After solid-liquid separation, a supernatant and perchlorate precipitate are obtained. (2) Add appropriate amount of iron salt and excess oxidant to the first supernatant in sequence and carry out oxidation reaction for at least 30 minutes. Then add pH adjuster to adjust the pH value of the reaction system to 7-10 until no more precipitation is produced. Then add appropriate amount of polyacrylamide to the reaction system and then carry out secondary solid-liquid separation to obtain the second supernatant and iron salt precipitate. (3) The supernatant from the second stage is filtered through an activated carbon filter for a period of time to remove perchlorate. Once the standard is met, the treatment of perchlorate wastewater is complete. The coagulant mentioned in step (1) is one or more of dodecyltrimethylammonium chloride, dodecyldimethylbenzylammonium chloride, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride.

2. The perchlorate wastewater treatment process as described in claim 1, characterized in that, The oxidation reaction in step (2) takes 30 to 60 minutes.

3. The perchlorate wastewater treatment process as described in claim 1, characterized in that, In step (1), the concentration of perchlorate is 30 mg / L to 1000 mg / L, based on the total mass of the perchlorate wastewater to be treated.

4. The perchlorate wastewater treatment process as described in claim 3, characterized in that, In step (1), the amount of cations in the added coagulant should not exceed 1.5 times the molar amount of perchlorate in the perchlorate wastewater to be treated, and / or Stirring is required during the reaction in step (1) at a speed of at least 100 r / min, and / or The reaction time for the coagulation reaction in step (1) is at least 3 minutes.

5. The perchlorate wastewater treatment process as described in claim 4, characterized in that, In step (1), the amount of cations in the added coagulant is 1.1 to 1.3 times the molar amount of perchlorate in the perchlorate wastewater to be treated, and / or Stirring is required during the reaction in step (1) at a speed of 100 r / min to 200 r / min, and / or The reaction time for the coagulation reaction in step (1) is 3 to 10 minutes.

6. The perchlorate wastewater treatment process as described in claim 1, characterized in that, In step (1), solid-liquid separation is achieved by centrifuge or filter press, and / or The coagulant aid mentioned in step (1) is one or more of bentonite, diatomite, and perlite, and / or Based on the volume of the perchlorate wastewater to be treated in step (1), the amount of coagulant added in step (1) is 1 to 2 g / L.

7. The perchlorate wastewater treatment process as described in claim 6, characterized in that, In step (1), solid-liquid separation is achieved using a plate and frame filter press, and / or The coagulant in step (1) is bentonite.

8. The perchlorate wastewater treatment process as described in claim 1, characterized in that, The iron salt mentioned in step (2) is selected from one or more of ferric chloride, ferrous sulfate, ferric sulfate, and polyferric sulfate, and / or In step (2), after adding an appropriate amount of iron salt to the supernatant, the total concentration of iron ions and / or ferrous ions in the supernatant is 0.1 to 0.3 g / L.

9. The perchlorate wastewater treatment process as described in claim 8, characterized in that, The iron salt mentioned in step (2) is ferrous sulfate.

10. The perchlorate wastewater treatment process as described in claim 1, characterized in that, The oxidant mentioned in step (2) is one of air, oxygen, hydrogen peroxide and ozone.

11. The perchlorate wastewater treatment process as described in claim 1, characterized in that, During the oxidation reaction in step (2), stirring is carried out continuously at a speed of at least 100 r / min.

12. The perchlorate wastewater treatment process as described in claim 11, characterized in that, During the oxidation reaction in step (2), the stirring is carried out continuously at a speed of 100 r / min to 200 r / min.

13. The perchlorate wastewater treatment process as described in claim 1, characterized in that, The pH adjuster mentioned in step (2) is one or more of calcium oxide, calcium hydroxide, sodium oxide, and sodium hydroxide.

14. The perchlorate wastewater treatment process as described in claim 1, characterized in that, Based on the volume of the perchlorate wastewater to be treated in step (1), the amount of polyacrylamide added in step (2) is 0.1–0.5 mg / L, and / or In step (2), secondary solid-liquid separation is achieved by using a centrifuge, filter press, or thickener.

15. The perchlorate wastewater treatment process as described in claim 14, characterized in that, In step (2), a secondary solid-liquid separation is achieved by using a thickener.

16. The perchlorate wastewater treatment process as described in claim 1, characterized in that, The filling material in the activated carbon filter in step (3) is modified activated carbon, and / or The supernatant from step (3) is filtered by an activated carbon filter for at least 2 minutes.

17. The perchlorate wastewater treatment process as described in claim 16, characterized in that, The time for the second-stage supernatant to be adsorbed and filtered by the activated carbon filter in step (3) is 2 to 10 minutes.

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