Organic sewage treatment method based on combined application of tetravalent iron process and ozone and application

Abstract

The invention discloses an organic sewage treatment method based on combined application of a tetravalent iron process and ozone and application. The method comprises the following steps: adjusting the pH value of target organic sewage to a first pH value; the method comprises the following steps: sequentially adding a target ozone solution, a target sodium persulfate solution and a target ferrous solution which are prepared in advance into target organic sewage, and reacting to obtain a first-stage solution; taking out a sewage sample with a target preset volume from the first-stage solution, and analyzing the concentration of various organic pollutants in each sewage sample; adjusting the pH value of the sewage in the first state to a second pH value; adding a target disinfectant into the first-stage solution, and reacting under a dark reaction condition to obtain a second-stage solution; and enriching the disinfection by-products corresponding to the second-stage solution, and quantitatively analyzing the concentration of the enriched disinfection by-products. According to the invention, high-efficiency removal of degradation-resistant organic pollutants can be realized, and disinfection by-products can be effectively reduced at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to an organic sewage treatment method based on the combined application of a tetravalent iron process and ozone and its application. Background Art

[0002] With the acceleration of industrialization and urbanization, water pollution is becoming increasingly serious, especially in urban sewage, which contains a large amount of organic pollutants. Emerging pollutants such as pharmaceuticals and personal care products (PPCPs) are typical representatives of this. These organic pollutants are usually difficult to remove by traditional water treatment methods. During the chlorination disinfection process after water treatment, disinfectants react with dissolved organic matter (DOM) in water to generate disinfection by-products (DBPs). Disinfection by-products such as chloroforms (THMs) and halogenated acetic acids (HAAs) not only have a negative impact on water quality, but may also pose a potential threat to human health, thus bringing greater challenges to the water treatment process.

[0003] As an emerging advanced oxidation method, ferric iron technology (Fe(IV)-AOPs) has been widely used in the field of water treatment in recent years. Fe(IV)-AOPs can effectively degrade organic pollutants in water by introducing iron ions (Fe(II)) to react with oxidants to generate ferric iron and active free radicals. It has good selectivity for pollutants. At present, common ferric iron treatment processes include ferrous iron / sodium peroxydisulfate (Fe(II) / PDS), ferrous iron / hypochlorous acid (Fe(II) / HClO), ferrous iron / sodium permonosulfate process (Fe(II) / PMS), etc. These technologies can effectively produce ferric iron, degrade organic pollutants in water, and adjust the structure of dissolved organic matter to reduce the generation of disinfection by-products. However, the single Fe(IV)-AOPs technology still has certain limitations in practical applications, especially when treating complex water quality. The treatment effect is not good or a higher amount of reactants may be required to achieve the purpose of degrading the target pollutants, resulting in increased costs, and some disinfection by-products may still be generated.

[0004] Among them, the ferrous iron / sodium persulfate process (Fe(II) / PDS) can effectively simplify the molecular structure of complex organic matter and reduce the generation of chlorination disinfection by-products, but the degradation effect on pharmaceutical organic matter is poor. Therefore, in practical applications, a higher dosage may be required to degrade organic pollutants. This not only increases operating costs, but may also lead to excessive iron ions in the water, thereby causing heavy metal pollution.

[0005] Among them, in the ferrous iron / hypochlorous acid process (Fe(II) / HClO), hypochlorous acid is easily decomposed in water and is extremely unstable. Although hypochlorous acid has strong disinfection and pollutant degradation capabilities, it is easy to generate more chlorinated disinfection byproducts, such as chloroacetic acid and chloroform, due to the addition of chlorine in water treatment. These byproducts not only affect water quality, but may also pose a potential hazard to human health, limiting its applicability in certain applications.

[0006] Among them, the ferrous iron / sodium permonosulfate process (Fe(II) / PMS) is very sensitive to the pH value of the water body and the presence of other ions or organic matter. A slight fluctuation in water quality conditions may lead to a significant decrease in oxidation efficiency, thereby reducing the degradation effect of organic pollutants, increasing uncertainty and operational difficulty in practical applications. At the same time, due to the strict requirements of the process on reaction conditions and the high consumption of oxidants, there are certain challenges to the economic feasibility of large-scale water treatment applications. Summary of the invention

[0007] In order to solve the technical problems in the prior art, the present invention provides an organic wastewater treatment method and application based on the combined application of tetravalent iron process and ozone, which can achieve efficient removal of difficult-to-degrade organic pollutants and effectively reduce the production of disinfection by-products. The overall process is economical, efficient and environmentally friendly, and is suitable for a variety of actual water treatment scenarios.

[0008] Specifically, the present invention includes the following contents.

[0009] The first aspect of the present invention provides a method for treating organic wastewater based on the combined application of a tetravalent iron process and ozone, comprising:

[0010] Step S1, adjusting the pH value of the target organic sewage to be treated to a first pH value; step S2, adding a pre-prepared target ozone solution, a target sodium persulfate solution and a target divalent iron solution to the target organic sewage after the pH value is adjusted to the first pH value in sequence for reaction to obtain a first-stage solution; step S3, taking out a sewage sample of a target preset volume from the first-stage solution every first target preset time, and after a reaction time of a second target preset time, obtaining a plurality of sewage samples at different time points, and analyzing the concentrations of various organic pollutants in each of the sewage samples; step S4, adjusting the pH value of the first-state sewage remaining after taking out a plurality of the sewage samples to a second pH value, the second pH value being greater than the first pH value; step S5, adding a target disinfectant to the first-stage solution after the pH value is adjusted to the second pH value, and reacting under dark reaction conditions for a third target preset time to obtain a second-stage solution; step S6, enriching the disinfection by-products corresponding to the second-stage solution, and quantitatively analyzing the concentration of the enriched disinfection by-products.

[0011] Preferably, the first pH value is in the range of 2.8-3.2, and the second pH value is in the range of 7.5-8.5.

[0012] Preferably, the first target preset time length is 1-1.2 min, the second target preset time length is 5-6 min, the third target preset time length is 2.5-3.5 d, and the target preset volume is 10-15 ml.

[0013] Preferably, in step 3, a liquid phase mass spectrometer is used to analyze the concentration of various organic pollutants in each of the sewage samples.

[0014] Preferably, in step 2, after the pre-prepared target ozone solution is added to the target organic sewage, the ozone concentration of the target organic sewage is 15-25 μmol / L.

[0015] Preferably, in step 2, after the pre-prepared target sodium persulfate solution is added to the target organic wastewater, the sodium persulfate concentration of the target organic wastewater is 180-220 μmol / L.

[0016] Preferably, in step 2, after the pre-prepared target divalent iron solution is added to the target organic wastewater, the divalent iron concentration of the target organic wastewater is 180-220 μmol / L.

[0017] Preferably, the target disinfectant is monochloramine disinfectant, and after adding the monochloramine disinfectant, the monochloramine disinfectant concentration of the first stage solution is 3-7 mg / LC 12.

[0018] Preferably, in step S6, the disinfection by-products corresponding to the second-stage solution are enriched, and the concentration of the enriched disinfection by-products is quantitatively analyzed, including: collecting 40-50 mL of the second-stage solution, enriching all the disinfection by-products of the second-stage solution by liquid-liquid extraction, and quantitatively analyzing the concentration of all the disinfection by-products using a triple quadrupole gas mass spectrometer.

[0019] The second aspect of the present invention provides an application of the organic wastewater treatment method based on the combined application of tetravalent iron process and ozone according to any one of the above items in the field of organic wastewater treatment.

[0020] The technical effects of the present invention include but are not limited to:

[0021] The present invention aims to overcome the problems faced by the prior art in treating complex water quality, such as high cost, low reaction efficiency, poor degradation of pharmaceutical organic pollutants, and generation of by-products. By generating tetravalent iron in ozone-containing water, the synergistic effect of Fe(II) / PDS and trace ozone is fully utilized. The main advantages are reflected in the following aspects:

[0022] (1) The oxidative degradation capacity of refractory organic matter is significantly enhanced. The introduction of trace ozone plays a key role in enhancing oxidation in the Fe(II) / PDS system, which can deeply degrade stubborn organic pollutants such as pharmaceuticals and personal care products (PPCPs) in water, greatly improving the overall treatment effect.

[0023] (2) Reduce the formation of disinfection by-products. The synergistic oxidation reaction can effectively modify the molecular structure of dissolved organic matter (DOM), and then significantly reduce the amount of disinfection by-products formed during the subsequent chlorination disinfection process, thereby ensuring water quality safety.

[0024] (3) Reduce dosage and processing costs. Since the addition of trace amounts of ozone can improve the oxidation efficiency of tetravalent iron, this process does not require a large increase in the dosage of agents such as sodium persulfate or iron ions. At the same time, low-concentration ozone is easy to synthesize and store, and will not affect human health, thereby effectively controlling operating costs and reflecting obvious economic advantages.

[0025] (4) Wide applicability: The present invention exhibits high degradation efficiency and good water quality safety under diverse water quality conditions such as urban sewage and industrial pharmaceutical wastewater, showing broad application potential and providing a new technical path for achieving sustainable utilization of water resources.

[0026] In summary, through the above-mentioned synergistic effect, the present invention can achieve efficient removal of difficult-to-degrade organic pollutants, while effectively reducing the generation of disinfection by-products. The overall process is economical, efficient, and environmentally friendly, and is suitable for a variety of actual water treatment scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the degradation efficiency [concentration] / [concentration]0 of sulfamethoxazole after treating the sewage containing the antibiotic-sulfamethoxazole in Example 1 using ferrous iron / sodium peroxydisulfate (Fe(II) / PDS), ferrous iron / hypochlorous acid (Fe(II) / HCl O), ferrous iron / sodium peroxymonosulfate process (Fe(II) / PMS) and the composite tetravalent iron water treatment process technology based on the combined application of Fe(II) / PDS and trace ozone provided in the embodiments of the present invention.

[0028] Figure 2 Schematic diagram of the concentration of disinfection by-products after three days of post-chlorination disinfection of the sewage in Example 1 using the ferrous iron / sodium peroxydisulfate (Fe(II) / PDS), ferrous iron / hypochlorous acid (Fe(II) / HCl O), ferrous iron / sodium peroxymonosulfate process (Fe(II) / PMS) and the composite ferric iron water treatment process technology based on the combined application of Fe(II) / PDS and trace ozone provided in the embodiments of the present invention.

[0029] Figure 3 Schematic diagram of the degradation efficiency [concentration] / [concentration]0 of trimethoprim after treating the sewage containing the antibiotic-trimethoprim in Example 2 using the ferrous iron / sodium peroxydisulfate (Fe(II) / PDS), ferrous iron / hypochlorous acid (Fe(II) / HCl O), ferrous iron / sodium peroxymonosulfate process (Fe(II) / PMS) and the composite tetravalent iron water treatment process technology based on the combined application of Fe(II) / PDS and trace ozone provided in the embodiments of the present invention.

[0030] Figure 4 Schematic diagram of the concentration of disinfection by-products after three days of post-chlorination disinfection of the sewage in Example 2 using the ferrous iron / sodium peroxydisulfate (Fe(II) / PDS), ferrous iron / hypochlorous acid (Fe(II) / HCl O), ferrous iron / sodium peroxymonosulfate process (Fe(II) / PMS) and the composite tetravalent iron water treatment process technology based on the combined application of Fe(II) / PDS and trace ozone provided in the embodiments of the present invention.

[0031] Figure 5Schematic diagram of the degradation efficiency of diclofenac [concentration] / [concentration]0 after the wastewater containing the non-steroidal anti-inflammatory drug-diclofenac in Example 3 is treated by ferrous iron / sodium peroxydisulfate (Fe(II) / PDS), ferrous iron / hypochlorous acid (Fe(II) / HCl O), ferrous iron / sodium peroxymonosulfate process (Fe(II) / PMS) and the composite tetravalent iron water treatment process technology based on the combined application of Fe(II) / PDS and trace ozone provided in the embodiments of the present invention.

[0032] Figure 6 Schematic diagram of the concentration of disinfection by-products after three days of post-chlorination disinfection of the sewage in Example 3 using the ferrous iron / sodium peroxydisulfate (Fe(II) / PDS), ferrous iron / hypochlorous acid (Fe(II) / HCl O), ferrous iron / sodium peroxymonosulfate process (Fe(II) / PMS) and the composite tetravalent iron water treatment process technology based on the combined application of Fe(II) / PDS and trace ozone provided in the embodiments of the present invention. DETAILED DESCRIPTION

[0033] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0034] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that the upper and lower limits of the scope and each intermediate value therebetween are specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0035] Unless otherwise specified, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail. Unless otherwise specified, "%" is a percentage based on weight.

[0036] Those skilled in the art should understand that other steps or operations may be included before or after the steps of this embodiment, or between any steps, for example, to further optimize and / or improve the method described in the present invention.

[0037] Example 1

[0038] This embodiment uses the technical solution of the present invention to treat and detect organic wastewater containing the antibiotic sulfamethoxazole, and the steps are as follows:

[0039] (1) Acquisition of actual water samples: Water samples were collected from a sewage treatment plant in Shanghai.

[0040] (2) Filter and collect water samples to remove obvious solid suspended impurities.

[0041] (3) Quantify the initial concentration of sulfamethoxazole using liquid chromatography-mass spectrometry.

[0042] (4) Preparation of ferrous iron stock solution and sodium persulfate stock solution:

[0043] Ferrous perchlorate Fe(II) (Fe(CI O4)2·6H2O) was dissolved in 0.01 mol / L perchloric acid solution to prepare Fe(II) stock solution, and its concentration was standardized and quantified using the 1,10-phenanthroline method, with a target concentration of 100 mmol / L. Sodium peroxydisulfate was dissolved in 500 mL ultrapure water to prepare a 100 mmol / L stock solution. Both the ferrous iron stock solution and the sodium peroxydisulfate stock solution were stored in a refrigerator at 4°C to avoid self-degradation.

[0044] (5) Preparation of ozone stock solution:

[0045] Oxygen was introduced into 4°C ultrapure water through an ozone generator to prepare ozone-rich water. The ozone concentration was standardized using ultraviolet absorbance measurement (ε260 = 3200 M-1 cm-1) to prepare a 100 μmol / L ozone stock solution for immediate use.

[0046] (6) Preparation of disinfectant:

[0047] Sodium hypochlorite and ammonium chloride were reacted at a molar ratio of 1:1.2 at pH = 8.0 to prepare a 20 mM monochloramine stock solution. The absorbance was measured at 245 nm and 295 nm by a spectrophotometer to quantify the concentration of the disinfectant, which was prepared and used immediately.

[0048] (7) Carry out the processing of the technical solution of the present invention and detect relevant data:

[0049] In 500mL of water, pre-adjust the pH to 3 (the range can be 2.8-3.2. Adjusting the pH value is necessary for the tetravalent iron process reaction, which can increase the formation and oxidation capacity of tetravalent iron), add 20μmol / L (the range can be 15-25μmol / L) of trace ozone, and then add 5mg / L of dissolved organic matter, 20μmol / L of target organic pollutants, 200μmol / L (the range can be 180-220μmol / L) of sodium persulfate oxidant and 200μmol / L (the range can be 180-220μmol / L) of divalent iron stock solution. React for a certain time, and collect 10mL of samples according to the reaction time of 0s, 1min, 2min, 3min, 4min, and 5min, and analyze the concentration of target organic pollutants with liquid phase mass spectrometer. Then adjust the pH to 8 (the range can be 7.5-8.5, and the pH value is adjusted to add disinfectants, increase the disinfection ability and the reaction time of disinfectants, because disinfectants are more stable at pH 8 and are not easy to self-degrade), add 5mg / LC l2 (the range can be 3-7mg / LC l2) of monochloramine disinfectant, and react for 3 days under dark reaction conditions (the range can be 2.5-3.5) to simulate the urban pipeline environment. After three days, collect 40mL of samples, enrich disinfection by-products by liquid-liquid extraction, and use triple quadrupole gas mass spectrometer to quantitatively analyze the concentrations of five common types of disinfection by-products. Among them, the steps of liquid-liquid extraction are: mix the sample to be tested with the organic solvent methyl tert-butyl ether containing the internal standard substance, and stir and shake thoroughly to promote the transfer of disinfection by-products from the aqueous phase to the organic phase. After standing and stratifying, the organic phase and the aqueous phase are separated, and the disinfection by-products are extracted into the upper organic phase. Finally, pure nitrogen is used to enrich and concentrate to obtain the final sample to be tested.

[0050] Among them, the disinfection by-product analysis steps are: analyze the sample to be tested using a triple quadrupole gas mass spectrometer to obtain the peak time and peak area of ​​the disinfection by-product and the internal standard substance, obtain the ratio based on the peak areas of the two, and substitute the ratio into the standard curve to obtain the quantitative concentration of the disinfection by-product.

[0051] In addition, under the same experimental conditions, three common tetravalent iron treatment processes were used in water bodies without ozone addition to conduct control experiments to calculate the concentrations of target pollutants and disinfection by-products. All experiments were repeated three times to verify the stability and reliability of the experimental results, reduce accidental errors, and ensure the accuracy and credibility of the data.

[0052] The experimental results are as attached Figure 1 and 2As shown, the target pollutant [concentration] / [concentration]0 measured by three common tetravalent iron treatment processes Fe(II) / PDS, Fe(II) / HClO, Fe(II) / PMS and the technical solution of the present invention (i.e., a composite tetravalent iron water treatment process using Fe(II) / PDS in combination with trace ozone) was 0.38, 0.15, 0.36 and 0.06; the concentrations of disinfection by-products after three days of chlorination were 37.44 μg / L, 53.76 μg / L, 41.58 μg / L and 34.60 μg / L, respectively.

[0053] Experimental results show that three common tetravalent iron treatment processes have achieved certain treatment effects in terms of target pollutant removal and disinfection byproduct generation after three days of chlorination, but there are still shortcomings of incomplete removal or high byproduct concentration. In contrast, the composite tetravalent iron water treatment process based on Fe (II) / PDS and trace ozone combined application proposed by the present invention has shown higher efficiency in terms of target pollutant removal ([concentration] / [concentration] 0 is only 0.06), and its disinfection product concentration after three days of chlorination disinfection is also relatively lower (34.60 μg / L), which fully illustrates that the technical solution of the present invention can greatly improve the degradation efficiency of organic pollutant sulfamethoxazole and inhibit the generation of disinfection byproducts. This result highlights the comprehensive advantages of the technology of the present invention in terms of efficiency and safety, and has good application prospects.

[0054] Example 2

[0055] This embodiment uses the technical solution of the present invention to process and detect organic wastewater containing the antibiotic trimethoprim, and the steps are as follows:

[0056] (1) Acquisition of actual water samples: Water samples were collected from a pharmaceutical factory in Guangzhou.

[0057] (2) Filter and collect water samples to remove obvious solid suspended impurities.

[0058] (3) Quantify the initial trimethoprim concentration using liquid chromatography-mass spectrometry.

[0059] (4) Carry out research according to steps (4), (5), (6) and (7) in Example 1.

[0060] The experimental results are as attached Figure 3 and 4As shown, the target pollutant [concentration] / [concentration]0 measured by three common tetravalent iron treatment processes Fe(II) / PDS, Fe(II) / HCl O, Fe(II) / PMS and the technical solution of the present invention (i.e., a composite tetravalent iron water treatment process using Fe(II) / PDS in combination with trace ozone) is 0.34, 0.25, 0.26 and 0.11; the concentrations of disinfection by-products after three days of chlorination are 41.27 μg / L, 59.74 μg / L, 43.06 μg / L and 36.35 μg / L, respectively.

[0061] The experimental results show that the three common tetravalent iron treatment processes have certain effects on the removal of target pollutants and the disinfection by-products produced by the subsequent three days of chlorination, but they still face limitations in degradation efficiency and by-product control. In contrast, the composite tetravalent iron water treatment process of the present invention, which synergistically applies trace ozone and Fe(II) / PDS, significantly reduces the [concentration] / [concentration]0 (0.11) of the target pollutants, while controlling the concentration of disinfection by-products at 36.35μg / L, which is better than other control groups. It can be seen that the synergistic effect of trace ozone and Fe(II) / PDS effectively inhibits the formation of disinfection by-products while efficiently degrading the organic pollutant trimethoprim, fully demonstrating the comprehensive advantages of the invention in water treatment efficiency and water quality safety.

[0062] Example 3

[0063] This embodiment uses the technical solution of the present invention to process and detect sewage mainly containing non-steroidal anti-inflammatory drugs-diclofenac, and the steps are as follows:

[0064] (1) Acquisition of actual water samples: Water samples were collected from a pharmaceutical company’s factory in Shenzhen.

[0065] (2) Filter and collect water samples to remove obvious solid suspended impurities.

[0066] (3) Quantify the initial concentration of diclofenac using liquid chromatography-mass spectrometry.

[0067] (4) Carry out research according to steps (4), (5), (6) and (7) in Example 1.

[0068] The experimental results are as attached Figure 5 and 6As shown, the target pollutant [concentration] / [concentration]0 measured by three common tetravalent iron treatment processes Fe(II) / PDS, Fe(II) / HCl O, Fe(II) / PMS and the technical solution of the present invention (i.e., a composite tetravalent iron water treatment process using Fe(II) / PDS in combination with trace ozone) is 0.26, 0.08, 0.33 and 0.05; the concentrations of disinfection by-products after three days of chlorination are 28.47 μg / L, 41.53 μg / L, 30.81 μg / L and 27.25 μg / L, respectively.

[0069] The experimental results show that the traditional tetravalent iron treatment process (Fe(II) / PDS, Fe(II) / HCl O, Fe(II) / PMS) has different degrees of deficiencies in the removal of target pollutants and the control of subsequent chlorinated byproducts. In contrast, the present invention uses a composite tetravalent iron water treatment process that uses trace ozone and Fe(II) / PDS in a coordinated manner. While significantly reducing the relative concentration of target pollutants ([concentration] / [concentration]0 is only 0.05), the concentration of disinfection byproducts after three days of chlorination is controlled at 27.25μg / L, which is better than the control group. The results show that the introduction of trace ozone can enhance the oxidative degradation ability of Fe(II) / PDS and effectively inhibit the formation of disinfection byproducts, further highlighting the comprehensive advantages of the present invention in water treatment efficiency and water quality safety assurance.

[0070] Although the present invention has been described with reference to exemplary embodiments, it should be understood that the present invention is not limited to the disclosed exemplary embodiments. Various adjustments or changes may be made to the exemplary embodiments of the present specification without departing from the scope or spirit of the present invention. The scope of the claims should be based on the broadest interpretation to cover all modifications and equivalent structures and functions.

Claims

1. A method for treating organic wastewater based on the combined application of tetravalent iron process and ozone, characterized in that: include: Step S1, adjusting the pH value of the target organic sewage to be treated to a first pH value; Step S2, adding a pre-prepared target ozone solution, a target sodium persulfate solution and a target divalent iron solution to the target organic wastewater after the pH value is adjusted to the first pH value in sequence to react and obtain a first-stage solution; Step S3, taking out a target preset volume of sewage sample from the first stage solution every first target preset time, and after a reaction time of a second target preset time, obtaining a plurality of sewage samples at different time points, and analyzing the concentration of various organic pollutants in each of the sewage samples; Step S4, adjusting the pH value of the sewage in the first state remaining after taking out the plurality of sewage samples to a second pH value, wherein the second pH value is greater than the first pH value; Step S5, adding a target disinfectant to the first-stage solution after the pH value is adjusted to the second pH value, and performing a reaction under dark reaction conditions for a third target preset time to obtain a second-stage solution; Step S6, enriching the disinfection by-products corresponding to the second-stage solution, and quantitatively analyzing the concentration of the enriched disinfection by-products.

2. The method for treating organic wastewater based on the combined application of tetravalent iron process and ozone according to claim 1, characterized in that: The first pH value ranges from 2.8 to 3.2, and the second pH value ranges from 7.5 to 8.

5.

3. The method for treating organic wastewater based on the combined application of tetravalent iron process and ozone according to claim 1, characterized in that: The first target preset time is 1-1.2 minutes, the second target preset time is 5-6 minutes, the third target preset time is 2.5-3.5 days, and the target preset volume is 10-15 ml.

4. The method for treating organic wastewater based on the combined application of tetravalent iron process and ozone according to claim 1, characterized in that: In step 3, a liquid phase mass spectrometer is used to analyze the concentration of various organic pollutants in each of the sewage samples.

5. The method for treating organic wastewater based on the combined application of tetravalent iron process and ozone according to claim 1, characterized in that: In step 2, after the pre-prepared target ozone solution is added to the target organic sewage, the ozone concentration of the target organic sewage is 15-25 μmol / L.

6. The method for treating organic wastewater based on the combined application of tetravalent iron process and ozone according to claim 1, characterized in that: In step 2, after the pre-prepared target sodium persulfate solution is added to the target organic wastewater, the sodium persulfate concentration of the target organic wastewater is 180-220 μmol / L.

7. The method for treating organic wastewater based on the combined application of tetravalent iron process and ozone according to claim 1, characterized in that: In step 2, after the pre-prepared target divalent iron solution is added to the target organic wastewater, the divalent iron concentration of the target organic wastewater is 180-220 μmol / L.

8. The method for treating organic wastewater based on the combined application of tetravalent iron process and ozone according to claim 1, characterized in that: The target disinfectant is monochloramine disinfectant, and after adding the monochloramine disinfectant, the monochloramine disinfectant concentration of the first stage solution is 3-7 mg / LCl2.

9. The method for treating organic wastewater based on the combined application of tetravalent iron process and ozone according to claim 8, characterized in that: In step S6, the disinfection by-products corresponding to the second-stage solution are enriched, and the concentration of the enriched disinfection by-products is quantitatively analyzed, including: 40-50 mL of the second-stage solution was collected, all the disinfection by-products in the second-stage solution were enriched by liquid-liquid extraction, and the concentrations of all the disinfection by-products were quantitatively analyzed using a triple quadrupole gas mass spectrometer.

10. Application of the organic wastewater treatment method based on the combined application of tetravalent iron process and ozone according to any one of claims 1 to 9 in the field of organic wastewater treatment.

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