Catalyst for advanced treatment of wastewater and preparation method and application thereof

Abstract

The application provides a catalyst for advanced treatment of wastewater, a preparation method and application thereof. The catalyst comprises an active component loaded on a carrier. The active component is a composite oxide, which comprises metal oxides of iron, manganese and copper, and an auxiliary catalytic oxide, which is one or more of oxides of tantalum, calcium, selenium and zinc. The catalyst for advanced treatment of wastewater has high loading strength and high wear resistance, and can be widely used in ozone catalytic oxidation and ozone / hydrogen peroxide synergistic catalytic oxidation for treatment of industrial wastewater. The catalyst is especially suitable for treatment of low-COD-concentration wastewater with a COD value lower than 150 mg / L. The COD value of the wastewater after the advanced treatment is lower than 60 mg / L, which meets the discharge standard. The preparation method of the catalyst for advanced treatment of wastewater is simple, and the process flow is simple, which is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a catalyst for advanced wastewater treatment, its preparation method, and its application. Background Technology

[0002] It is worth noting that the COD removal rate of wastewater after conventional treatment has essentially reached its limit. Conventional processes are no longer sufficient to remove this type of recalcitrant organic pollutant, making the treatment of such low-concentration COD industrial organic wastewater quite challenging. Furthermore, the carbon, nitrogen, and phosphorus ratios in low-concentration COD wastewater do not meet the metabolic needs of microorganisms. Therefore, if biological methods are used for advanced wastewater treatment, carbon sources need to be added, increasing operating costs. Currently, advanced oxidation technologies are commonly used to further remove recalcitrant organic pollutants from this type of low-concentration COD wastewater. The mechanism of advanced oxidation technology is mainly based on the formation of hydroxyl radicals, which then degrade organic pollutants in the water into carbon dioxide and water. Hydroxyl radicals have a strong oxidizing ability and can directly oxidize trace amounts of organic matter in the water into water and carbon dioxide.

[0003] Common advanced oxidation processes include the Fenton process and the ozone process:

[0004] The Fenton process refers to the degradation of recalcitrant organic compounds by H₂O₂ generating highly oxidizing hydroxyl radicals (·OH) and other reactive oxygen species in the presence of ferrous ions under acidic conditions. This reaction is a chain reaction, starting with the generation of ·OH, with other reactive oxygen species and reaction intermediates forming the chain nodes. The chain terminates when all reactive oxygen species are consumed. During the Fenton reaction, Fe... 2+ Oxidized to Fe 3+ The chemical sludge, which settles as iron sludge, requires land for treatment, transportation, and storage, and incurs additional sludge disposal costs, thus hindering the development of the Fenton process in the field of deep treatment of low-concentration COD industrial organic wastewater.

[0005] Ozone possesses strong oxidizing properties, second only to fluorine, ·OH, and O (atomic oxygen) in oxidizing ability. Its oxidizing power is 1.52 times that of elemental chlorine, enabling it to oxidize almost all organic pollutants in water. Ozone catalytic oxidation includes direct oxidation reactions and free radical indirect oxidation reactions. Ozone catalytic oxidation technology adsorbs ozone molecules at active sites on the catalyst surface. These ozone molecules react with water molecules or surface hydroxyl groups through a chain reaction, generating a large number of free radicals. These free radicals react with organic pollutants on the catalyst surface or in the liquid phase, causing rapid degradation and even mineralization. This allows highly stable and recalcitrant organic pollutants that cannot be degraded by ordinary ozone oxidation to be instantly decomposed and oxidized into CO2 and H2O. It is clear that the catalyst is a key factor in this ozone catalytic oxidation process. With the increasing implementation of stricter emission standards for industrial and urban wastewater, the development of more efficient ozone catalytic oxidation catalysts has become an urgent problem to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention discloses a catalyst for advanced wastewater treatment, its preparation method, and its application. The catalyst uses metal oxides as the main active component, exhibits high loading strength and high wear resistance, and can be widely used for industrial low-concentration wastewater, with the COD value of the wastewater after advanced treatment being below 60 mg / L. The method for preparing this catalyst is simple, has a short process, and is suitable for large-scale industrial production.

[0007] Specifically, on one hand, the catalyst for advanced wastewater treatment of the present invention includes a metal active component supported on a carrier; the metal active component is a composite metal oxide, including metal oxides of iron, manganese, and copper, and an auxiliary catalytic oxide, wherein the auxiliary catalytic oxide is one or more of metal oxides of tantalum, calcium, selenium, and zinc.

[0008] Transition metals or one or more noble metals such as Pt and Pd are commonly used as active components in ozone catalytic oxidation catalysts. Based on extensive experimental research, the research team of this invention unexpectedly discovered that catalysts prepared using a combination of main catalytic metal oxides and auxiliary catalytic oxides as active components can efficiently treat wastewater with COD values ​​below 150 mg / L. In particular, the wastewater treatment catalyst obtained by using main catalytic metal oxides, including iron, manganese, and copper oxides, in combination with auxiliary catalytic oxides as the active component support can achieve a COD removal rate more than 1.4 times higher than that of treatment processes without catalysts when treating wastewater with COD values ​​below 150 mg / L, resulting in COD values ​​below 60 mg / L, meeting emission standards. The auxiliary catalytic oxides are one or more oxides of tantalum, calcium, selenium, and zinc.

[0009] Based on the above findings, the research team of this invention conducted extensive exploratory experiments on the amount of main catalytic metal oxide added to the catalyst for advanced wastewater treatment and the ratio between the three main catalytic metal oxides. Optionally, the mass of the metal elements iron, manganese, and copper in the catalyst is 0.1% to 10% of the mass of the support, preferably 1% to 5%; optionally, the mass ratio of the metal elements iron, manganese, and copper in the composite oxide is 10 to 100:1 to 10:1 to 10. The test examples of this invention provide the technical effects of different amounts of main catalytic metal oxides and different masses of iron, manganese, and copper in the catalyst for advanced wastewater treatment.

[0010] Based on the above findings, the research team of this invention explored the effect of the amount of auxiliary catalytic oxide added on the effectiveness of the catalyst for advanced wastewater treatment. Experiments revealed that the mass percentage of tantalum, calcium, selenium, and zinc in the auxiliary catalytic oxide, calculated by elemental mass, is 0.01% to 1% of the carrier mass, preferably 0.05% to 0.5%. The embodiments of this invention demonstrate the impact of variations in the mass percentage of tantalum, calcium, selenium, and zinc in the auxiliary catalytic oxide on the effectiveness of the advanced wastewater treatment technology.

[0011] The research team of this invention further discovered through extensive experiments that the type of support for the active component in the catalyst for advanced wastewater treatment and the particle size of the support will affect the catalytic effect of the catalyst. Optionally, the support is silicon-modified alumina microspheres. It should be noted that the silicon-modified alumina microspheres mentioned in this invention refer to silicon-modified alumina microspheres that are doped, impregnated, or mechanically mixed; the shape of the silicon-modified alumina microspheres is not limited in this invention, but is preferably spherical; the diameter of the silicon-modified alumina microspheres is 3~5mm.

[0012] The catalyst for advanced wastewater treatment of this invention uses a special active component support to catalyze the efficient oxidation of organic matter in wastewater with ozone. Those skilled in the art will understand that the catalyst for advanced wastewater treatment of this invention is not only suitable for advanced treatment of wastewater with COD below 150 mg / L, but also for routine treatment of other types of industrial wastewater with higher COD values.

[0013] On the other hand, the present invention proposes a method for preparing a catalyst for advanced wastewater treatment, the method comprising the following steps:

[0014] (1) The silicon-modified alumina microspheres were cleaned and dried to obtain dry carrier microspheres.

[0015] (2) Dissolve one or more salts of iron, manganese, copper, and auxiliary catalytic elements such as tantalum, calcium, selenium, and zinc in demineralized water to obtain a salt mixture solution. Note that the salts used in this step are soluble salts, such as nitrates, sulfates, and chlorides. Those skilled in the art can select other soluble salts of the main catalytic metal elements (iron, manganese, and copper) and auxiliary catalytic elements through non-creative labor to prepare catalysts for advanced wastewater treatment. All technical solutions formed thereby are within the scope of protection of this invention.

[0016] (3) Using the equal volume impregnation method, the dried carrier microspheres prepared in step (1) are impregnated in the metal salt mixed solution, stirred evenly, and then dried and calcined to obtain the catalyst for deep treatment of wastewater.

[0017] The medium-volume impregnation method of this invention refers to a method for preparing supported catalysts by impregnation in which the volume of the impregnating liquid is equal to the pore volume of the solid support. Based on this method, the element content in the prepared catalyst for advanced wastewater treatment can be further controlled by adjusting the amount of the main catalytic metal element and the auxiliary catalytic element added to the salt mixture solution. Furthermore, the research team of this invention explored the optimal amounts of iron, manganese, and copper salts and auxiliary catalytic elements used in the preparation method, and optimized the diameter of the silicon-modified alumina microspheres used.

[0018] In step (3), the stirring temperature and time are not limited, and stirring can be carried out in the temperature range of 30~60℃ for 1~2 hours. This invention does not limit the specific drying operation; those skilled in the art can choose heating drying, vacuum drying, or rotary drying as needed, and the resulting technical solutions are all within the protection scope of this invention; rotary drying can be carried out in the temperature range of 70~90℃. Optionally, the impregnated silicon-modified alumina microspheres can be pre-calcined and then further calcined at 500~1000℃, preferably at 800~1000℃, for 2~4 hours.

[0019] On the other hand, the present invention proposes a method for advanced wastewater treatment using the above-mentioned catalyst for advanced wastewater treatment, the method comprising steps S1 and S2:

[0020] S1, the above-mentioned catalyst for advanced wastewater treatment is loaded into the reactor. It should be noted that the reactor used in this invention is not limited. In actual operation, suitable equipment can be selected for wastewater treatment according to the operating conditions, such as tower reactors, reaction tanks, reaction pipes, etc. All technical solutions formed thereby are within the scope of protection of this invention.

[0021] In this method, the COD of the wastewater to be treated is below 150 mg / L. Considering that the pH value of the wastewater affects the selection of the ozone catalytic oxidation reaction mechanism, ozone catalytic oxidation in strongly acidic media is mainly a direct oxidation reaction, while in alkaline media it is mainly a free radical indirect oxidation reaction. Before using the catalyst for advanced water treatment of this invention for ozone catalytic oxidation, the team of this invention pretreated the wastewater to be treated, preferably by adjusting the pH value of the wastewater to 7-10.

[0022] S2, the wastewater to be treated and ozone are introduced into the reactor from the bottom of the reactor to react.

[0023] To promote sufficient contact and oxidation between the wastewater and ozone, the research team optimized the relative amounts of wastewater and ozone, as well as the rates at which they were introduced from the bottom of the reactor. Optionally, the ozone dosage relative to the wastewater is 10-100 mg / L. Optionally, the flow rate of the wastewater in step S2 is 1-10 ml / min.

[0024] In addition, this invention proposes another method for advanced wastewater treatment using the aforementioned catalyst, which includes the following steps:

[0025] Step 1: Load the aforementioned catalyst for advanced wastewater treatment into the reactor;

[0026] Step 2: Add hydrogen peroxide to the wastewater to be treated and stir evenly to obtain pretreated wastewater;

[0027] Step 3: The pretreated wastewater and ozone are introduced into the reactor from the bottom to react.

[0028] To improve the removal rate of recalcitrant organic matter from wastewater by ozone, recent research has increasingly focused on synergistic catalytic systems of ozone and hydrogen peroxide. The reaction mechanism includes reactions 1-4:

[0029] Reaction 1: H2O2 → HO2 - +H + Reaction 2: O3 + HO2 - →·OH+O2 - +O2, Reaction 3: O3 + O2 - →O3 - +O2, Reaction 4: O3 - +H₂O→·OH+HO - +O2.

[0030] In this advanced wastewater treatment method, the catalytic oxidation system composed of catalyst and ozone can promote the decomposition of hydroxyl radicals by ozone. After adding hydrogen peroxide as an initiator, it forms a catalytic oxidation system with ozone, which can promote the generation of hydroxyl radicals by ozone decomposition. At the same time, the composite metal oxide supported catalyst has multiple active metal sites. After hydrogen peroxide is added to the reaction system, it can simultaneously form an ozone catalytic oxidation system and a heterogeneous Fenton oxidation system in the catalyst, further increasing the concentration of hydroxyl radicals in the solution.

[0031] Furthermore, to promote sufficient contact and oxidation between the wastewater to be treated and ozone, the research team of this invention: a. optimized the pH value of the pretreated wastewater; optionally, the pH value of the pretreated wastewater is 7-10. b. optimized the dosage of hydrogen peroxide; optionally, the concentration of hydrogen peroxide in the pretreated wastewater is 10-100 ppm. c. optimized the relative dosage of pretreated wastewater and ozone, as well as the rates at which they are input from the bottom of the reactor. Optionally, the dosage of ozone relative to the pretreated wastewater is 10-100 mg / L. Optionally, the flow rate of the pretreated wastewater in step 3 is 1-10 ml / min.

[0032] Generally, the higher the concentration of hydroxyl radicals in the solution, the better the removal effect on organic matter in wastewater. Data from the embodiments of this invention verify that, compared with the treatment process without a catalyst, the ozone / hydrogen peroxide synergistic catalytic oxidation method for deep treatment of wastewater can increase the COD removal rate by more than 2.5 times, resulting in COD in the wastewater being below 60 mg / L, meeting the emission standards.

[0033] Compared with existing technologies, the catalyst for advanced wastewater treatment in this invention uses iron, manganese, and copper oxides as the main catalytic metal oxides, combined with one or more of tantalum, calcium, selenium, and zinc oxides as active components. The catalyst exhibits high loading strength and high wear resistance, and can be widely used in ozone catalytic oxidation and ozone / hydrogen peroxide synergistic catalytic oxidation for treating industrial wastewater. It is particularly suitable for the advanced treatment of industrial wastewater with a COD below 150 mg / L, resulting in a COD below 60 mg / L in the treated wastewater. The preparation method of the catalyst for advanced wastewater treatment in this invention is simple, the process flow is streamlined, and it is suitable for large-scale industrial production. Attached Figure Description

[0034] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1 The image shows a SEM image of the catalyst for advanced wastewater treatment prepared in Example 1.2.

[0036] Figure 2 This is a SEM image of the catalyst for advanced wastewater treatment prepared in Example 1.4;

[0037] Figure 3 This is a SEM image of the catalyst for advanced wastewater treatment prepared in Example 1.5;

[0038] Figure 4 This is a SEM image of the catalyst for advanced wastewater treatment prepared in Example 1.6;

[0039] Figure 5 This is a finished product image of the catalyst for advanced wastewater treatment prepared in Example 1.6. Detailed Implementation

[0040] To facilitate understanding of the present invention, a more comprehensive description is provided below, along with preferred embodiments. However, it should be understood that these embodiments are merely for more detailed explanation and should not be construed as limiting the invention in any way, i.e., not limiting the scope of protection of the invention. Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods, unless otherwise specified, are conventional methods.

[0041] Test Example

[0042] The catalyst for advanced wastewater treatment of this invention comprises an active component supported on a carrier, which includes a primary catalytic metal oxide (i.e., oxides of iron, manganese, and copper) and a secondary catalytic oxide (i.e., one or more oxides of tantalum, calcium, selenium, and zinc). To optimize the catalyst's performance, this test example explored the amount of primary catalytic metal oxide added to the catalyst and the ratio between the three primary catalytic metal oxides.

[0043] Specifically, in this test example, a test catalyst containing a main catalytic metal oxide was prepared, and the test catalyst was used for ozone / hydrogen peroxide synergistic catalytic oxidation of wastewater for advanced treatment.

[0044] Specifically, (1) Modified alumina microspheres with a diameter of 3-5 mm and a silicon content of 3% were selected as the carrier. The carrier was cleaned with demineralized water and then dried at 50°C to obtain dry carrier microspheres. (2) 20.384 g of ferric nitrate, 0.768 g of manganese nitrate and 0.138 g of copper nitrate were dissolved in demineralized water to obtain a salt mixture solution. The total mass of the three metal elements, iron, manganese and copper, was 5 g, and the mass ratio of Fe:Mn:Cu was 100:5:1. (3) 500 g of dry carrier microspheres were taken and immersed in the above salt mixture solution in equal volume and stirred at 30°C for 4 h. Then, the catalyst was subjected to reduced pressure rotary evaporation at 70°C. The dried catalyst was pre-calcined at 500°C for 4 h and then calcined at 900°C for 4 h to complete the preparation of the catalyst for testing.

[0045] The catalyst used in the above tests was added to an ozone / hydrogen peroxide synergistic catalytic oxidation wastewater treatment reactor to perform advanced treatment on low-concentration COD biochemical effluent (COD=124mg / L) from a wastewater treatment plant in a chemical industrial park. The experimental steps are as follows:

[0046] Step 1: Take 300g of the above-mentioned test catalyst and pack it into an ozone / hydrogen peroxide synergistic catalytic oxidation wastewater treatment reactor. The reactor inner diameter is 5cm, and the packing height is approximately 20cm. Step 2: Adjust the pH of the wastewater treatment plant's biological effluent to 8, then add hydrogen peroxide to a concentration of 80ppm. After stirring evenly, pretreated wastewater is obtained. Step 3: Pump the pretreated wastewater into the reactor from below at a flow rate of 10ml / min. Simultaneously, add ozone to the reactor from below at a dosage of 100mg / L for reaction. After running for 1 hour, take samples and analyze the COD value of the effluent after ozone / hydrogen peroxide synergistic catalytic oxidation treatment.

[0047] This test includes test cases 1.1-1.6 where other conditions and parameters remain constant, with the only variable being the mass ratio of the metallic elements iron, manganese, and copper. Additionally, this test includes test cases 1.3, 1.7, and 1.8 where other conditions and parameters remain constant, with the only variable being the mass ratio of the metallic elements iron, manganese, and copper to the carrier mass.

[0048] Comparative Example

[0049] In the comparative example, other conditions and parameters in the advanced wastewater treatment method remained unchanged, but ozone / hydrogen peroxide co-catalytic oxidation of wastewater was performed without a catalyst. After catalysis, the COD value of the effluent was analyzed and detected.

[0050] The specific process parameters and conditions for test examples 1-5 and the comparative examples are shown in Table 1.

[0051] Table 1

[0052]

[0053] As confirmed by test examples 1.1-1.6 in Table 1, the mass ratio of iron, manganese, and copper in the composite metal oxide of the prepared wastewater advanced treatment catalyst is 10~100:1~10:1~10, and more preferably 20:5:1. As verified by test examples 1.3, 1.7, and 1.8 in Table 1, the mass of iron, manganese, and copper in the catalyst is 0.1%~10% of the carrier mass, preferably 1%~5%.

[0054] Example 1

[0055] This embodiment demonstrates the process flow for preparing the catalyst for advanced wastewater treatment of the present invention under specific operating conditions, as well as the process flow for using the prepared catalyst for advanced wastewater treatment to perform ozone / hydrogen peroxide synergistic catalytic oxidation for advanced wastewater treatment. It should be noted that this process flow is merely a demonstration of a preferred method and does not limit the scope of protection of the present invention.

[0056] (1) Modified alumina microspheres with a diameter of 3-5 mm and a silicon content of 3% were used as carriers. The carriers were cleaned with demineralized water and then dried at 50°C to obtain dry carrier microspheres. (2) 50.094 g of ferric nitrate, 9.339 g of manganese nitrate and 1.692 g of copper nitrate were dissolved in demineralized water to obtain a salt mixture solution. The total mass of the three elements, iron, manganese and copper, was 15 g. The mass ratio of Fe:Mn:Cu was the preferred ratio of the three elements, i.e., 20:5:1. Then, one or more salts of auxiliary catalytic elements, tantalum, calcium, selenium and zinc, were dissolved in the solution and stirred evenly. (3) 500 g of dry carrier microspheres were taken and immersed in the above salt mixture solution in equal volume. The mixture was stirred at 30°C for 4 h. Then, the mixture was subjected to reduced pressure rotary evaporation at 70°C. The dried catalyst was pre-calcined at 500°C for 4 h and then calcined at 900°C for 4 h to complete the preparation of the catalyst.

[0057] The prepared catalyst was added to an ozone / hydrogen peroxide synergistic catalytic oxidation wastewater treatment reactor to perform advanced treatment on low-concentration COD biochemical effluent (COD=124mg / L) from a wastewater treatment plant in a chemical industrial park. The experimental steps are as follows:

[0058] Step 1: Take 300g of the catalyst prepared above and pack it into an ozone / hydrogen peroxide synergistic catalytic oxidation wastewater treatment reactor. The reactor inner diameter is 5cm, and the packing height is approximately 20cm. Step 2: Adjust the pH of the wastewater treatment plant's biological effluent to 8, then add hydrogen peroxide to a concentration of 80ppm. After stirring evenly, pretreated wastewater is obtained. Step 3: Pump the pretreated wastewater into the reactor from below at a flow rate of 10ml / min. Simultaneously, add ozone from below the reactor at a dosage of 100mg / L to initiate the reaction. After 1 hour of operation, take samples and analyze the COD value of the effluent after ozone / hydrogen peroxide synergistic catalytic oxidation treatment.

[0059] This embodiment sets other conditions and parameters unchanged, with the only variable being the type and amount of auxiliary catalytic element dissolved in the solution, as in Examples 1.1-1.6. The specific process parameters and conditions for Examples 1.1-1.6 and the comparative examples are shown in Table 2. The SEM image of the catalyst for advanced wastewater treatment prepared in Example 1.2 is shown below. Figure 1 As shown, the SEM image of the catalyst for advanced wastewater treatment prepared in Example 1.4 is as follows. Figure 2 As shown; the SEM image of the catalyst for advanced wastewater treatment prepared in Example 1.5 is shown below. Figure 3 As shown; the SEM image of the catalyst for advanced wastewater treatment prepared in Example 1.6 is shown below. Figure 4 As shown, the finished product of the catalyst is as follows Figure 5 As shown.

[0060] Table 2

[0061]

[0062] As verified by Table 2, the catalyst for advanced wastewater treatment prepared in this embodiment is suitable for advanced treatment of wastewater with a COD value of less than 150 mg / L, and the COD value of the treated effluent is less than 60 mg / L, meeting stricter wastewater discharge standards. Compared with the comparative example, the ozone / hydrogen peroxide synergistic catalytic oxidation method for advanced wastewater treatment can achieve a COD removal rate increase of more than 2.5 times. In the catalyst for advanced wastewater treatment prepared in this embodiment, the mass percentage of tantalum, calcium, selenium, and zinc in the auxiliary catalytic oxide is 0.01%~1% of the carrier mass, preferably 0.05%~0.5%.

[0063] Example 2

[0064] This embodiment uses the catalyst for advanced wastewater treatment prepared in Example 1.6 for ozone catalytic oxidation wastewater treatment. The catalyst is added to the ozone / hydrogen peroxide synergistic catalytic oxidation wastewater treatment reactor. By setting different hydrogen peroxide dosages (including a condition with a hydrogen peroxide dosage of 0), advanced treatment of low-concentration COD biochemical effluent (COD=124mg / L) from a wastewater treatment plant in a chemical industrial park is carried out. The experimental steps are as follows:

[0065] S1: Take 300g of the catalyst prepared in Example 1.6 and pack it into an ozone / hydrogen peroxide synergistic catalytic oxidation wastewater treatment reactor. The reactor has an inner diameter of 5cm and a packing height of approximately 20cm. Adjust the pH of the biochemical effluent from the wastewater treatment plant to 8. Do not add hydrogen peroxide or add an appropriate amount of hydrogen peroxide. After stirring evenly, obtain pretreated wastewater and then wastewater to be treated. S2: Pump the wastewater to be treated into the reactor from the bottom at a flow rate of 10ml / min. Simultaneously, add ozone from the bottom of the reactor at an addition rate of 100mg / L relative to the wastewater to be treated. After running for 1 hour, take a sample and analyze the COD value of the effluent after ozone catalytic oxidation treatment.

[0066] This embodiment sets other conditions and parameters unchanged, with the only variable being the amount of hydrogen peroxide added relative to the pretreated wastewater. The specific process parameters and conditions of Embodiments 1.6, 2.1-2.4 and the comparative examples are shown in Table 3.

[0067] Table 3

[0068]

[0069] As verified by Table 3, the advanced treatment catalyst prepared in Example 1.6 can be used for both ozone / hydrogen peroxide synergistic catalytic oxidation and ozone catalytic oxidation advanced wastewater treatment processes. The COD value of the treated effluent is below 60 mg / L, meeting stricter wastewater discharge standards. In step 3, the ozone dosage relative to the pretreated wastewater is 10~100 mg / L. Compared with the comparative example, the COD removal rate can be increased by more than 1.4 times using ozone catalytic oxidation for advanced wastewater treatment. A comparison between Example 1.6 and Example 2.4 shows that the COD removal rate of the advanced wastewater treatment process can be increased by more than 10% through ozone / hydrogen peroxide synergistic catalytic oxidation.

[0070] Example 3

[0071] This embodiment uses the catalyst for advanced wastewater treatment prepared in Example 1.6 to perform ozone / hydrogen peroxide synergistic catalytic oxidation treatment on the low-concentration COD biochemical effluent (COD=124mg / L) from a wastewater treatment plant in a chemical industrial park. The experimental steps are as follows:

[0072] Step 1: Take 300g of the catalyst prepared in Example 1.6 and pack it into an ozone / hydrogen peroxide synergistic catalytic oxidation wastewater treatment reactor. The reactor inner diameter is 5cm, and the packing height is approximately 20cm. Step 2: Adjust the pH of the wastewater treatment plant's biological effluent to 7, then add hydrogen peroxide to a concentration of 80ppm. After stirring evenly, pretreated wastewater is obtained. Step 3: Pump the pretreated wastewater into the reactor from below at a flow rate of 10ml / min. Simultaneously, add ozone from below the reactor at a dosage of 100mg / L relative to the pretreated wastewater for reaction. After running for 1 hour, take samples and analyze the COD value of the effluent after ozone / hydrogen peroxide synergistic catalytic oxidation treatment.

[0073] This embodiment sets up Examples 3.1-3.3 with other conditions and parameters unchanged and the only variable being the pH value of the solution. The specific process parameters and conditions of the comparative example, Example 1.6, and Examples 3.1-3.3 are shown in Table 4.

[0074] Table 4

[0075]

[0076] As can be seen from Table 4, adjusting the wastewater to a slightly alkaline state in the specific process helps reduce COD in the wastewater through ozone / hydrogen peroxide synergistic catalytic oxidation. The suitable pretreatment wastewater pH value for the wastewater deep treatment method in this embodiment is 6~11, preferably 7~10.

[0077] It should be noted that the above description is a further detailed explanation of the present invention in conjunction with specific embodiments, and should not be construed as limiting the specific implementation of the present invention to these descriptions; the dimensional data in this embodiment do not necessarily limit the technical solution, but merely illustrate one specific working condition. For those skilled in the art, various simple improvements and modifications can be made without departing from the concept of the present invention, and all such improvements and modifications should be considered to fall within the scope of protection of the present invention.

Claims

1. A catalyst for advanced treatment of wastewater, characterized by comprising a metal oxide and a zeolite. The catalyst comprises an active component supported on a carrier; the active component is a composite oxide comprising metal oxides of iron, manganese and copper and an auxiliary catalytic oxide which is a selenium oxide or a mixture of a selenium oxide and one or both of oxides of tantalum and zinc; The mass of the metal elements iron, manganese and copper in the catalyst is 0.1%-10% of the mass of the carrier; The mass of the auxiliary catalytic elements tantalum, selenium and zinc in the auxiliary catalytic oxide is 0.01%-1% of the mass of the carrier; The carrier is silicon-modified alumina pellets; The mass ratio of the metal elements iron, manganese and copper in the composite oxide is 10-100:1-10:1-10.

2. The catalyst for advanced treatment of wastewater according to claim 1, characterized by, The mass of the metal elements iron, manganese and copper in the catalyst is 1%-5% of the mass of the carrier.

3. The catalyst for advanced treatment of wastewater according to claim 1, characterized by, The mass of the auxiliary catalytic elements tantalum, selenium and zinc in the auxiliary catalytic oxide is 0.05%-0.5% of the mass of the carrier.

4. The catalyst for advanced treatment of wastewater according to claim 1, characterized by, The silicon-modified alumina pellets have a diameter of 3-5 mm.

5. A method for producing the catalyst for advanced treatment of waste water according to any one of claims 1 to 4, characterized by, The method comprises the following steps: (1) washing and drying silicon-modified alumina pellets to obtain dried carrier pellets; (2) dissolving iron, manganese and copper salts and an auxiliary catalytic element selenium salt or a mixture of selenium and one or both of salts of tantalum and zinc in desalted water to obtain a salt mixture solution; (3) using an equal-volume impregnation method, impregnating the dried carrier pellets prepared in step (1) in the salt mixture solution, stirring uniformly, drying and calcining to obtain the catalyst for advanced treatment of wastewater.

6. The method for producing a catalyst for advanced treatment of wastewater according to claim 5, characterized by, The mass of the metal elements iron, manganese and copper in the catalyst is 0.1%-10% of the mass of the carrier.

7. The method for producing a catalyst for advanced treatment of wastewater according to claim 6, characterized by, The mass of the metal elements iron, manganese and copper in the catalyst is 1%-5% of the mass of the carrier.

8. The method for preparing a catalyst for advanced treatment of wastewater according to claim 5, characterized by, The mass ratio of the metal elements iron, manganese and copper in the catalyst is 10-100:1-10:1-10.

9. The method for preparing a catalyst for advanced treatment of wastewater according to claim 5, characterized by, The mass of the auxiliary catalytic elements tantalum, selenium and zinc in the catalyst is 0.01%-1% of the mass of the carrier.

10. The method for producing a catalyst for advanced treatment of wastewater according to claim 9, characterized by, The mass of the auxiliary catalytic elements tantalum, selenium and zinc in the catalyst is 0.05%-0.5% of the mass of the carrier.

11. The method for preparing a catalyst for advanced treatment of wastewater according to claim 5, characterized by, The silicon-modified alumina pellets have a diameter of 3-5 mm.

12. The method for preparing a catalyst for advanced treatment of wastewater according to claim 5, characterized by, The stirring temperature in step (3) is 30-60°C, the stirring time is 1-2 h; rotary evaporation drying is used, the rotary evaporation drying temperature is 70-90°C; the calcining temperature is 500-1000°C, and the calcining time is 2-4 h.

13. The method for producing a catalyst for advanced treatment of wastewater according to claim 12, characterized by, The calcining temperature is 800-1000°C.

14. A method for advanced treatment of wastewater, characterized by, The method comprises the following steps: S1, loading the catalyst for advanced treatment of wastewater according to claim 1 into a reactor; S2, inputting wastewater to be treated and ozone from the lower part of the reactor into the reactor for reaction.

15. The method for advanced treatment of wastewater according to claim 14, characterized in that, The pH value of the wastewater to be treated is 6-11.

16. The method for advanced treatment of wastewater according to claim 15, characterized in that, The pH value of the wastewater to be treated is 7-10.

17. The method for advanced treatment of wastewater according to claim 14, characterized in that, The dosage of ozone relative to the wastewater to be treated in step S2 is 10-100 mg / L; the flow rate of the wastewater to be treated in step S2 is 1-10 ml / min.

18. A method for advanced treatment of wastewater, characterized by, The method comprises the following steps: Step 1, loading the catalyst for advanced treatment of wastewater according to claim 1 into a reactor; Step 2, adding hydrogen peroxide to wastewater to be treated and stirring uniformly to obtain pretreated wastewater; Step 3, the pretreated wastewater and ozone are input into the reactor from the lower part of the reactor to react.

19. The method for advanced treatment of wastewater according to claim 18, characterized in that, The pH value of the pretreated wastewater is 6-11.

20. The method for advanced treatment of wastewater according to claim 19, characterized in that, The pH value of the pretreated wastewater is 7-10.

21. The method for advanced treatment of wastewater according to claim 18, wherein, The concentration of hydrogen peroxide in the pretreated wastewater is 10-100 ppm.

22. The method for advanced treatment of wastewater according to claim 18, wherein, The adding amount of ozone in the step 3 is 10-100 mg / L relative to the pretreated wastewater; the flow rate of the pretreated wastewater in the step 3 is 1-10 ml / min.

23. The advanced wastewater treatment method according to any one of claims 14-22, characterized in that, The COD value of the wastewater to be treated is less than 150 mg / L.

Images