A method for advanced treatment of wastewater by using iron-based catalyst to catalyze hydrogen peroxide and ozone

Abstract

The present application relates to wastewater treatment technical field, especially to a kind of method for utilizing iron-based catalyst catalytic hydrogen peroxide and ozone advanced treatment of wastewater.The present application first adds hydrogen peroxide in wastewater, obtains mixed water sample;Then mixed water sample is passed through the reaction column filled with iron-based catalyst from bottom to top, while ozone is introduced into the bottom of reaction column, and the advanced treatment of wastewater is realized by the synergistic cooperation of iron-based catalyst, hydrogen peroxide and ozone.The method provided by the present application can significantly improve the utilization rate of ozone, significantly improve the treatment effect of wastewater;For the wastewater with initial COD concentration of 100-500mg / L, the effluent COD after treatment can reach the surface water quality standard (GB 3838-2002 III standard, COD≤20mg / L), and the method is expected to be widely applied in environmental pollution control.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method for deep treatment of wastewater using iron-based catalysts to catalyze hydrogen peroxide and ozone. Background Technology

[0002] Currently, with the rapid development of human life and industrial production, surface and groundwater pollution is becoming increasingly serious. Industrial wastewater from industries such as dyeing, pharmaceuticals, chemicals, and petroleum, as well as domestic wastewater, if discharged directly without treatment, poses multiple threats, including eutrophication of surface and groundwater bodies, increased chemical oxygen demand (COD), and pathogen contamination. However, the complex nature of the wastewater, containing toxic substances, can easily cause poisoning and collapse of biochemical systems, affecting the normal operation of wastewater treatment plants. In recent years, with the rapid development of industry and the advancement of urbanization, the large-scale discharge and improper disposal of industrial wastewater, along with the extensive use of fertilizers and pesticides, have led to the widespread presence of toxic, harmful, and non-biodegradable organic pollutants such as polycyclic aromatic hydrocarbons, dyes, and pesticides in aquatic environments, seriously threatening human health and highlighting the growing problem of pollution.

[0003] The real-world aquatic environment contains a wide variety of organic pollutants, most of which are highly toxic, often requiring catalysts to activate the oxidant. Existing catalysts are complex to prepare, such as supported modified materials based on kaolin and attapulgite, and bimetallic / multimetallic catalyst materials. These catalysts suffer from high costs or secondary pollution, limiting the application of heterogeneous catalysts. On the other hand, conventional advanced oxidation processes suffer from high reagent costs, large sludge production, and high disposal costs.

[0004] Therefore, it is crucial to provide a technical solution that can solve the above-mentioned technical problems. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a method for the deep treatment of wastewater using an iron-based catalyst catalyzing hydrogen peroxide and ozone. The invention first adds hydrogen peroxide to the wastewater to obtain a mixed water sample. Then, the mixed water sample is passed from bottom to top through a reaction column filled with an iron-based catalyst, while ozone is simultaneously introduced at the bottom of the reaction column. Through the synergistic effect of the iron-based catalyst, hydrogen peroxide, and ozone (the mass ratio of ozone to hydrogen peroxide is 0.25–4), deep treatment of the wastewater is achieved. The method provided by this invention solves the technical problem of existing ozone oxidation or Fenton oxidation methods failing to meet standards for deep wastewater treatment. It significantly improves ozone utilization and wastewater treatment efficiency (solving problems such as low ozone utilization and high wastewater treatment costs). For wastewater with an initial COD concentration of 100–500 mg / L, the treated effluent COD can meet the Class III surface water quality standard (GB 3838-2002 Class III standard, COD ≤ 20 mg / L). This method is expected to be widely applied in environmental pollution control.

[0006] Technical principle of the invention:

[0007] Reducible iron-based materials, represented by zero-valent iron, can remove some biotoxic pollutants through their reducing action, improve the biodegradability of wastewater, and can be used as wastewater pretreatment.

[0008] Ozone, as a strong oxidant, has an oxidizing capacity second only to fluorine, and higher than commonly used oxidants such as oxygen, chlorine, and permanganates. Under ideal reaction conditions, ozone can oxidize most elements and compounds in aqueous solutions to their highest oxidation states, exhibiting a strong oxidative degradation effect on organic matter in water. However, the low ozone utilization rate in ozone oxidation technology leads to excessively high investment and treatment costs, limiting its application in organic wastewater treatment.

[0009] This invention couples an iron-based catalyst with hydrogen peroxide and ozone in a reaction (iron-based catalytic perozone (FPO)), promoting the reaction of ·OH and ·O. 2- The generation of various reactive species such as Fe(IV) can significantly improve ozone utilization efficiency and wastewater treatment efficiency by controlling the addition ratio of ozone and hydrogen peroxide. Furthermore, modified zero-valent iron obtained through sulfidation, carbonization, and various oxyacid anion modifications can further regulate the ability of zero-valent iron to activate hydrogen peroxide and ozone, thereby further enhancing reactivity, utilization rate, and lifespan of zero-valent iron.

[0010] The specific reaction mechanism is as follows:

[0011] Fe + 0.5O₂ + H₂O → Fe 2+ +2OH -

[0012] Fe 2+ +H₂O₂→Fe 3+ +OH - +·OH

[0013] Fe 2+ +O3→Fe 3+ +·O3 -

[0014] ·O3 - +H + →O2+·OH

[0015] H2O2→H + +HO2 -

[0016] O3+OH - →·HO2+·O2 -

[0017] O3+·O2 - →·O3 - +O2

[0018] ·O3 - +H + →·HO+O2

[0019] The objective of this invention can be achieved through the following technical solutions:

[0020] The first objective of this invention is to provide a method for the deep treatment of wastewater using iron-based catalysts to catalyze hydrogen peroxide and ozone, comprising the following steps:

[0021] (S1) Add hydrogen peroxide to the wastewater to obtain a mixed water sample;

[0022] (S2) The mixed water sample is passed from bottom to top through a reaction column filled with an iron-based catalyst, while ozone is introduced at the bottom of the reaction column. The deep treatment of wastewater is achieved through the synergistic effect of the iron-based catalyst, hydrogen peroxide and ozone.

[0023] In one embodiment of the present invention, in step (S1), the amount of hydrogen peroxide added is 50-500 mg / L.

[0024] In one embodiment of the present invention, in step (S2), the iron-based catalyst is prepared by the following method:

[0025] Iron-based materials were ball-milled to obtain iron-based catalysts;

[0026] The iron-based material is zero-valent iron, or a mixture of zero-valent iron and a modifier.

[0027] In one embodiment of the present invention, the amount of the modifier added is 0 to 5% of the mass fraction of zero-valent iron.

[0028] In one embodiment of the present invention, the modifier is selected from one or more of sulfides, glucose, oxyacids or oxyacid salts.

[0029] In one embodiment of the present invention, the sulfide is sodium sulfide;

[0030] The oxyacid is selected from one of oxalic acid, phosphoric acid, boric acid, formic acid, or silicic acid.

[0031] In one embodiment of the present invention, the ball milling process is carried out at a rotation speed of 400-600 rpm / min for 2-4 hours.

[0032] In one embodiment of the present invention, the iron-based catalyst has a particle size of 10 to 100 μm.

[0033] In one embodiment of the present invention, the mass ratio of ozone to hydrogen peroxide is 1:0.25 to 4.

[0034] In one embodiment of the present invention, when the COD of the wastewater is 0 to 200 mg / L, the mass ratio of ozone to hydrogen peroxide is 1:0.25 to 1.

[0035] When the COD of the wastewater is 200-500 mg / L, the mass ratio of ozone to hydrogen peroxide is 1:2-4.

[0036] In one embodiment of the present invention, the residence time of the mixed water sample and ozone in the reaction column is 0.5 to 2 hours.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) This invention provides for the first time a method of coupling hydrogen peroxide and ozone with an iron-based catalyst and applies it to the treatment of actual wastewater. The COD of the treated wastewater can meet the requirements of the Class III surface water quality standard (GB 3838-2002 Class III standard, COD≤20mg / L).

[0039] (2) The method of coupling hydrogen peroxide and ozone with iron-based catalysts can significantly improve the utilization efficiency of ozone and improve the removal efficiency of COD. The preparation methods of zero-valent iron and modified zero-valent iron are simple and inexpensive, and are expected to be widely used in environmental pollution control.

[0040] In summary, this invention can solve the problems of difficulty in meeting standards or excessively high treatment costs for industrial or domestic wastewater; in particular, it addresses the issues of high cost and low reactivity of traditional advanced oxidation technologies, significantly improving wastewater treatment efficiency and reducing operating costs during the reaction process, thereby achieving wastewater treatment standards improvement and emission reduction. Attached Figure Description

[0041] Figure 1 This is a schematic diagram of the wastewater treatment device used in an embodiment of the present invention;

[0042] The following are labeled in the diagram: 1. Hydrogen peroxide dosing tank; 2. Wastewater tank; 3. Metering pump; 4. Reaction column; 5. Separator; 6. Aeration disc; 7. Ozone generator; 8. Oxygen generator; 9. Iron-based catalyst; 10. Liquid outlet.

[0043] Figure 2 The images show the effluent effects of different batches of wastewater treated by using an iron-based catalyst to catalyze the deep treatment of wastewater with hydrogen peroxide and ozone in Example 4. Detailed Implementation

[0044] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0045] In the following embodiments, the wastewater treatment device is as follows: Figure 1 As shown, the system includes a hydrogen peroxide dosing tank 1, a wastewater tank 2, a metering pump 3, a reaction column 4, an aeration disc 6, an ozone generator 7, and an oxygen generator 8. The outlet of the hydrogen peroxide dosing tank 1 is connected to the wastewater tank 2 to provide hydrogen peroxide. The wastewater tank 2 is connected to the bottom of the reaction column 4 via a wastewater pipeline. An aeration disc 6 is installed at the bottom of the reaction column 4. The oxygen generator 8 is connected to the ozone generator 7, and the ozone generator 7 is connected to the aeration disc 6 to provide ozone to the reaction column 4. The reaction column 4 is filled with an iron-based catalyst 9. A mesh 5 is installed at the bottom of the iron-based catalyst 9 (to prevent the iron-based catalyst from flowing out with the mixed water sample). Several layers of mesh are installed at the top and bottom of the iron-based catalyst 9. An outlet 10 is installed at the top of the reaction column 4. A metering pump 3 is installed on the wastewater pipeline to control the wastewater flow rate. The reaction column 4 processes 1.5L of mixed water sample per batch.

[0046] In use, an external motor powers the wastewater treatment device, and the hydrogen peroxide addition tank 1 provides hydrogen peroxide to the wastewater tank 2. When the concentration of hydrogen peroxide in the wastewater in the wastewater tank 2 reaches the required concentration, the addition of hydrogen peroxide is stopped, and the wastewater and hydrogen peroxide are mixed to obtain a mixed water sample.

[0047] The mixed water sample is transported from wastewater tank 2 to reaction column 4 through wastewater pipeline. When the required volume of the mixed water sample to be treated is reached, the transport of the mixed water sample is stopped.

[0048] Oxygen generator 8 provides a high concentration of oxygen to ozone generator 7. Ozone generator 7 converts oxygen into ozone and adds it to the bottom of reaction column 4 through aeration disc 6 to provide ozone for the mixed water sample in reaction column 4. When the concentration of ozone in the mixed water sample in reaction column reaches the required concentration, the ozone addition is stopped.

[0049] At this point, the iron-based catalyst, ozone, and hydrogen peroxide in reaction column 4 work together to treat the wastewater.

[0050] Other devices can be used to replace this wastewater treatment device, as long as they can achieve the synergistic treatment of wastewater by iron-based catalysts, hydrogen peroxide, and ozone during the wastewater treatment process.

[0051] Iron can be purchased at retail price;

[0052] Zero-valent iron sulfide (particle size 100 μm) was prepared by the following method:

[0053] Zero-valent iron was mixed with sodium sulfide (2% by mass of zero-valent iron) and then ball-milled (500 rpm / min, 30 min forward and 30 min reverse, repeated four times for a total of 4 h) to obtain zero-valent iron sulfide.

[0054] Sodium sulfide has good reducing power, which can reduce and remove the zero-valent iron passivation layer and improve the activity of the material. At the same time, sodium sulfide also has a certain degree of hydrophobicity. After modifying zero-valent iron with sodium sulfide, the surface hydrophobicity can reduce the reaction between the material and water molecules, reduce the ineffective consumption of zero-valent iron electrons by reducing water, and help improve the electron selectivity of the material.

[0055] Zero-valent iron carbide (particle size 100 μm) was prepared by the following method:

[0056] Zero-valent iron was mixed with glucose (2% of the mass fraction of zero-valent iron) and then ball-milled (500 rpm / min, 30 min forward and 30 min reverse, repeated four times for a total of 4 h) to obtain carbonized zero-valent iron.

[0057] Because of its reducing properties, glucose, when ball-milled with zero-valent iron, can not only reduce and remove the passivation layer on the surface of zero-valent iron, but also crack glucose through mechanochemical methods to produce reactive species such as carbon dioxide free radicals, thus accelerating the treatment of pollutants.

[0058] Zero-valent iron oxalate (particle size 100 μm) was prepared by the following method:

[0059] Zero-valent iron was mixed with oxalic acid (2% of the mass fraction of zero-valent iron) and then ball-milled (500 rpm / min, 30 min forward and 30 min reverse, repeated four times for a total of 4 h) to obtain oxalicized zero-valent iron.

[0060] Oxalic acid has reducing properties and strong coordination complexing ability. It can not only reduce and remove the passivation layer on the surface of zero-valent iron, but also form ferrous oxalate proton channels on the surface, which can significantly promote the reducing activity of zero-valent iron.

[0061] Phosphorylated zero-valent iron (particle size 100 μm) was prepared by the following method:

[0062] Zero-valent iron was mixed with potassium dihydrogen phosphate (2% by mass of zero-valent iron) and then ball-milled (500 rpm / min, 30 min forward and 30 min reverse, repeated four times for a total of 4 h) to obtain phosphorylated zero-valent iron.

[0063] Phosphoric acid has a significant coordination ability, which can coordinate to the surface of zero-valent iron and promote the shedding of the passivation layer on the surface of zero-valent iron. At the same time, phosphate ions have a significant proton confinement ability, which can participate in the reaction by forming suspended protons, thereby enhancing the activity of zero-valent iron.

[0064] Boronized zero-valent iron (particle size 100 μm) was prepared by the following method:

[0065] Zero-valent iron was mixed with boron oxide (2% by mass of zero-valent iron) and then ball-milled (500 rpm / min, 30 min forward and 30 min reverse, repeated four times for a total of 4 h) to obtain borate-treated zero-valent iron.

[0066] Ball milling boron oxide with zero-valent iron can change the crystal structure of zero-valent iron, enhance its conductivity, and thus enhance its activity.

[0067] Zero-valent iron silicate (particle size 100 μm) was prepared by the following method:

[0068] Zero-valent iron was mixed with sodium silicate (2% by mass of zero-valent iron) and then ball-milled (500 rpm / min, 30 min forward and 30 min reverse, repeated four times for a total of 4 h) to obtain silicated zero-valent iron.

[0069] Silicic acid is a typical weak acid molecule. Silicate ions have a significant ability to confine protons. By confining active hydrogen, they can reduce side reactions in the zero-valent iron reaction process and enhance the activity of reactions that require protons.

[0070] Simulated wastewater 1 was prepared by the following method:

[0071] Add COD standard solution (final concentration 150 mg / L), sodium bicarbonate (final concentration 10 mg / L), sodium sulfate (final concentration 10 mg / L), and potassium chloride (final concentration 10 mg / L) to deionized water and mix well.

[0072] Simulated wastewater 2 was prepared by the following method:

[0073] Add COD standard solution (final concentration 500 mg / L), sodium bicarbonate (final concentration 10 mg / L), sodium sulfate (final concentration 10 mg / L), and potassium chloride (final concentration 10 mg / L) to deionized water and mix well.

[0074] Unless otherwise specified, all reagents used in the following embodiments are commercially available reagents, and all detection methods and techniques used are conventional methods and techniques in the art.

[0075] Example 1

[0076] This embodiment provides a method for deep wastewater treatment using iron-based catalysts to catalyze hydrogen peroxide and ozone, as detailed below:

[0077] In this embodiment, the wastewater being treated is industrial wastewater from a sewage treatment plant in Jingzhou. The initial COD of this wastewater is 132 mg / L, and the pH is 8.4.

[0078] Group settings:

[0079] Control group 1 (hydrogen peroxide treatment only): 350 mg / L (final concentration) of 30% hydrogen peroxide was added to the wastewater, and the COD concentration of the effluent was measured after stirring for 1 hour.

[0080] Control group 2 (ozone treatment group only): 150 mg / L (final concentration) of ozone was added to the wastewater, and the COD concentration of the effluent was measured after stirring and reacting for 1 hour.

[0081] Control group 3 (hydrogen peroxide + iron-based catalyst treatment group): 30% hydrogen peroxide at 350 mg / L (final concentration) was added to the wastewater to obtain a mixed water sample;

[0082] The mixed water sample was then passed through the reaction column of the wastewater treatment device (the reaction column was filled with zero-valent iron), and left to stand for 1 hour (column reaction for 1 hour). The COD concentration of the effluent was then measured.

[0083] Control group 4 (ozone + iron-based catalyst treatment group): Wastewater was passed through the reaction column of the wastewater treatment device (the reaction column was filled with zero-valent iron), and ozone was introduced into the bottom of the reaction column (to a final concentration of 150 mg / L), and left to stand for 1 hour (column reaction for 1 hour). The COD concentration of the effluent was then measured.

[0084] Experimental group (hydrogen peroxide + ozone + iron-based catalyst treatment group): 30% hydrogen peroxide at 350 mg / L (final concentration) was added to the wastewater to obtain a mixed water sample;

[0085] The mixed water sample was passed through the reaction column of the wastewater treatment device (the reaction column was filled with zero-valent iron), and ozone was introduced at the bottom of the reaction column (to a final concentration of 150 mg / L). The sample was left to stand for 1 hour (column reaction for 1 hour), and the COD concentration of the effluent was measured.

[0086] The changes in COD concentration and pH in each treatment group are shown in Table 1.

[0087] Table 1: COD Removal Efficiency of Different Oxidation Processes in Wastewater

[0088]

[0089] pass Figure 1 It can be observed that the wastewater effluent COD concentration after treatment with hydrogen peroxide + ozone + iron-based catalyst was the lowest, reduced to 24 mg / L, which was significantly better than the hydrogen peroxide only treatment group, the ozone only treatment group, the hydrogen peroxide + iron-based catalyst treatment group, and the ozone + iron-based catalyst treatment group.

[0090] Example 2

[0091] This embodiment provides a method for deep wastewater treatment using iron-based catalysts to catalyze hydrogen peroxide and ozone, as detailed below:

[0092] In this embodiment, the wastewater being treated is industrial wastewater from a sewage treatment plant in Jingzhou. The initial COD of this wastewater is 132 mg / L, and the pH is 8.4.

[0093] Add 350 mg / L (final concentration) of 30% hydrogen peroxide to the wastewater to obtain a mixed water sample;

[0094] Treatment Group 1: The mixed water sample was passed through the reaction column of the wastewater treatment device (the reaction column was filled with zero-valent iron), and ozone was introduced at the bottom of the reaction column (to a final concentration of 150 mg / L). The sample was left to stand for 1 hour (column reaction for 1 hour), and the COD concentration of the effluent was measured.

[0095] Treatment Group 2: The mixed water sample was passed through the reaction column of the wastewater treatment device (the reaction column was filled with zero-valent iron sulfide), and ozone was introduced at the bottom of the reaction column (to a final concentration of 150 mg / L). The sample was left to stand for 1 hour (column reaction for 1 hour), and the COD concentration of the effluent was measured.

[0096] Treatment Group 3: The mixed water sample is passed through the reaction column of the wastewater treatment device (the reaction column is filled with zero-valent iron carbide), and ozone is introduced at the bottom of the reaction column (to a final concentration of 150 mg / L), left to stand for 1 hour (column reaction for 1 hour), and the COD concentration of the effluent is measured.

[0097] Treatment Group 4: The mixed water sample was passed through the reaction column of the wastewater treatment device (the reaction column was filled with oxalate zero-valent iron), and ozone was introduced at the bottom of the reaction column (to a final concentration of 150 mg / L). The sample was left to stand for 1 hour (column reaction for 1 hour), and the COD concentration of the effluent was measured.

[0098] Treatment Group 5: The mixed water sample is passed through the reaction column of the wastewater treatment device (the reaction column is filled with phosphorylated zero-valent iron), and ozone is introduced at the bottom of the reaction column (to a final concentration of 150 mg / L), left to stand for 1 hour (column reaction for 1 hour), and the COD concentration of the effluent is measured.

[0099] Treatment Group 6: The mixed water sample is passed through the reaction column of the wastewater treatment device (the reaction column is filled with borate zero-valent iron), and ozone is introduced at the bottom of the reaction column (to a final concentration of 150 mg / L), left to stand for 1 hour (column reaction for 1 hour), and the COD concentration of the effluent is measured.

[0100] Treatment Group 7: The mixed water sample is passed through the reaction column of the wastewater treatment device (the reaction column is filled with silicated zero-valent iron), and ozone is introduced at the bottom of the reaction column (to a final concentration of 150 mg / L), left to stand for 1 hour (column reaction for 1 hour), and the COD concentration of the effluent is measured.

[0101] The changes in COD concentration and pH in each treatment group are shown in Table 2.

[0102] Table 2. Effects of different iron-based catalysts on the removal of COD from wastewater via hydrogen peroxide and ozone processes.

[0103]

[0104] pass Figure 2 It can be observed that zero-valent iron (ZVFe) and various modified ZVFe exhibit good COD removal activity for hydrogen peroxide and ozone. Among them, the sulfidation, carbonization, oxalation, phosphorylation, borate treatment, and silicate modification of ZVFe show better catalytic activity for hydrogen peroxide and ozone than ZVFe alone. Furthermore, after oxalation, borate treatment, and silicate modification of ZVFe for hydrogen peroxide and ozone removal, the effluent COD is below 20 mg / L, meeting the requirements of the Class III surface water quality standard (GB 3838-2002 Class III standard, COD ≤ 20 mg / L).

[0105] Example 3

[0106] This embodiment provides a method for deep wastewater treatment using iron-based catalysts to catalyze hydrogen peroxide and ozone, as detailed below:

[0107] Add 200 mg / L (final concentration) of 30% hydrogen peroxide to wastewater 1 (simulated wastewater 1: COD is 150 mg / L) to obtain mixed water sample 1;

[0108] Add 200 mg / L (final concentration) of 30% hydrogen peroxide to wastewater 2 (simulated wastewater 2: COD is 500 mg / L) to obtain mixed water sample 2;

[0109] Treatment Group 1: Mixed water sample 1 and mixed water sample 2 were passed through the reaction column of the wastewater treatment device (the reaction column was filled with silicated zero-valent iron), and ozone was introduced at the bottom of the reaction column (the mass ratio of ozone to hydrogen peroxide (O / H ratio) was maintained at 0.25). The mixture was left to stand for 1 hour (column reaction for 1 hour), and the COD concentration of the effluent was measured.

[0110] Treatment Group 2: Mixed water sample 1 and mixed water sample 2 were passed through the reaction column of the wastewater treatment device (the reaction column was filled with silicated zero-valent iron), and ozone was introduced at the bottom of the reaction column (the mass ratio of ozone to hydrogen peroxide (O / H ratio) was maintained at 0.5). The mixture was left to stand for 1 hour (column reaction for 1 hour), and the COD concentration of the effluent was measured.

[0111] Treatment Group 3: Mixed water sample 1 and mixed water sample 2 were passed through the reaction column of the wastewater treatment device (the reaction column was filled with silicated zero-valent iron), and ozone was introduced into the bottom of the reaction column (the mass ratio of ozone to hydrogen peroxide (O / H ratio) was maintained at 1). The mixture was left to stand for 1 hour (column reaction for 1 hour), and the COD concentration of the effluent was measured.

[0112] Treatment Group 4: Mixed water sample 1 and mixed water sample 2 were passed through the reaction column of the wastewater treatment device (the reaction column was filled with silicated zero-valent iron), and ozone was introduced into the bottom of the reaction column (the mass ratio of ozone to hydrogen peroxide (O / H ratio) was maintained at 2), and left for 1 hour (column reaction 1 hour), and the COD concentration of the effluent was detected.

[0113] Treatment Group 5: Mixed water sample 1 and mixed water sample 2 were passed through the reaction column of the wastewater treatment device (the reaction column was filled with silicated zero-valent iron), and ozone was introduced into the bottom of the reaction column (the mass ratio of ozone to hydrogen peroxide (O / H ratio) was maintained at 4), and the mixture was left to stand for 1 hour (column reaction for 1 hour). The COD concentration of the effluent was then measured.

[0114] The changes in COD concentration and pH in each treatment group are shown in Table 3.

[0115] Table 3. COD Removal Efficiency of Different O / H Ratio Catalytic Hydrogen Peroxide and Ozone Processes in Wastewater

[0116]

[0117] Table 3 shows that for low-concentration COD wastewater (wastewater 1 in this example), the COD removal effect is negatively correlated with the O / H ratio. As the O / H ratio increases, the COD removal effect slightly decreases. When the O / H ratio is in the range of 0.25 to 1, the COD concentration can be stably treated to below 20 mg / L, meeting the requirements of the Class III surface water quality standard (GB 3838-2002 Class III standard, COD ≤ 20 mg / L). For high-concentration COD wastewater (wastewater 2 in this example), the COD removal effect is positively correlated with the O / H ratio. As the O / H ratio increases, the COD removal effect improves. When the O / H ratio is in the range of 2 to 4, the COD concentration can be stably treated to below 20 mg / L, meeting the requirements of the Class III surface water quality standard (GB 3838-2002 Class III standard, COD ≤ 20 mg / L).

[0118] Example 4

[0119] This embodiment provides a method for deep wastewater treatment using iron-based catalysts to catalyze hydrogen peroxide and ozone, as detailed below:

[0120] In this embodiment, the wastewater being treated is industrial wastewater from a sewage treatment plant in Jingzhou. The initial COD of this wastewater is 132 mg / L, and the pH is 8.4.

[0121] Add 300 mg / L (final concentration) of 30% hydrogen peroxide to the wastewater to obtain a mixed water sample;

[0122] The mixed water samples were passed through the reaction column of the wastewater treatment device (the reaction column was filled with silicated zero-valent iron), and ozone (to a final concentration of 150 mg / L) was introduced at the bottom of the reaction column. The samples were left to stand for 1 hour (column reaction time of 1 hour). Four batches of wastewater were treated continuously using the same reaction column, and the COD concentration of each batch of wastewater was measured.

[0123] The changes in COD concentration and pH after each treatment are shown in Table 4 and Figure 2 As shown:

[0124] Table 3. COD Removal Efficiency of Different Treatment Batches of Wastewater by Catalytic Hydrogen Peroxide and Ozone Processes

[0125] Processing batches 0 1 2 3 4 COD (mg / L) 132 18 14 15 12 pH 8.4 8.4 8.5 8.5 8.4

[0126] Through Table 4 and Figure 2The results show that after treatment, the COD of the first batch of industrial wastewater treated by this process decreased from 132 mg / L to 18 mg / L, and the color and turbidity of the effluent were significantly reduced. The COD of the treated effluent met the requirements of the Class III surface water quality standard (GB3838-2002 Class III standard, COD≤20 mg / L). Further treatment of the second batch of wastewater reduced the COD to 14 mg / L; the third batch reduced it to 15 mg / L; and the fourth batch reduced it to 12 mg / L. The COD treatment effect improved with the increasing number of uses of the iron-based catalyst. This is because the catalyst is in the activation stage at the beginning of the reaction, and its activity is not yet at its best. With each use, the catalyst is gradually fully activated, and its activity further increases to a stable operating level. The above results indicate that this process is effective, simple to operate, and has low operating costs.

[0127] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the interpretation of the present invention, without departing from the scope of the invention, should be within the protection scope of the present invention.

Claims

1. A method for deep treatment of wastewater using iron-based catalysts to catalyze hydrogen peroxide and ozone, characterized in that, Includes the following steps: (S1) Add hydrogen peroxide to the wastewater to obtain a mixed water sample; (S2) The mixed water sample is passed from bottom to top through a reaction column filled with an iron-based catalyst, while ozone is introduced at the bottom of the reaction column. The deep treatment of wastewater is achieved through the synergistic effect of the iron-based catalyst, hydrogen peroxide and ozone.

2. The method for deep treatment of wastewater using iron-based catalysts to catalyze hydrogen peroxide and ozone, as described in claim 1, is characterized in that... In step (S1), the amount of hydrogen peroxide added is 50-500 mg / L.

3. The method for deep treatment of wastewater using iron-based catalysts to catalyze hydrogen peroxide and ozone, as described in claim 1, is characterized in that... Step (S2), the iron-based catalyst is prepared by the following method: Iron-based materials were ball-milled to obtain iron-based catalysts; The iron-based material is zero-valent iron, or a mixture of zero-valent iron and a modifier.

4. The method for deep treatment of wastewater using iron-based catalysts to catalyze hydrogen peroxide and ozone, as described in claim 3, is characterized in that... In the mixture of zero-valent iron and the modifier, the amount of modifier added is 1 to 5% of the mass fraction of zero-valent iron.

5. The method for deep treatment of wastewater using iron-based catalysts to catalyze hydrogen peroxide and ozone, as described in claim 3, is characterized in that... The modifier is selected from one or more of sulfides, glucose, oxyacids or oxyacid salts.

6. The method for deep treatment of wastewater using iron-based catalysts to catalyze hydrogen peroxide and ozone, as described in claim 3, is characterized in that... During the ball milling process, the rotation speed is 400-600 rpm / min, and the time is 2-4 hours.

7. The method for deep treatment of wastewater using iron-based catalysts to catalyze hydrogen peroxide and ozone, as described in claim 3, is characterized in that... The iron-based catalyst has a particle size of 10–100 μm.

8. The method for deep treatment of wastewater using iron-based catalysts to catalyze hydrogen peroxide and ozone, as described in claim 3, is characterized in that... The mass ratio of ozone to hydrogen peroxide is 1:0.25 to 4.

9. A method for deep treatment of wastewater using iron-based catalysts to catalyze hydrogen peroxide and ozone, as described in claim 8, characterized in that... When the COD of the wastewater is 0-200 mg / L, the mass ratio of ozone to hydrogen peroxide is 1:0.25-1. When the COD of the wastewater is 200-500 mg / L, the mass ratio of ozone to hydrogen peroxide is 1:2-4.

10. The method for deep treatment of wastewater using iron-based catalysts to catalyze hydrogen peroxide and ozone, as described in claim 1, is characterized in that... The residence time of the mixed water sample and ozone in the reaction column is 0.5 to 2 hours.

Images