A method for removing odorous substances based on oxidation technology

Abstract

The present invention discloses a method for removing odorous substances based on oxidation technology, which relates to the field of water purification and treatment. The method comprises the following steps: adjusting the 2-MIB concentration in raw water and controlling the pH to a range conducive to the oxidation reaction; introducing the raw water into an oxidation device containing a reaction column, adding ozone and hydrogen peroxide, and adding a transition metal oxide catalyst and an organic synergist for synergistic oxidation, wherein the transition metal oxide catalyst is at least one of MnO2, Fe2O3, and CuO, which is prepared into nano-sized particles and loaded onto a porous carrier; and subjecting the oxidized water to a coagulation and sedimentation treatment. By adjusting the raw water quality and using ozone, hydrogen peroxide, a transition metal oxide catalyst, and an organic synergist for synergistic oxidation, the present invention effectively improves the odorous substance removal rate, enhances catalyst stability and recycling efficiency, addresses the shortcomings of existing technologies in odorous substance removal, and meets the demand for standard treatment of odorous substances in drinking water.

Description

Technical Field

[0001] The present invention relates to the technical field of water purification and treatment, and in particular to a method for removing odorous substances based on oxidation technology. Background Art

[0002] 2-MIB (2-methylisoborneol) and geosmin are common substances that cause water odor. The "Sanitary Standard for Drinking Water" stipulates that the concentration of 2-MIB and geosmin must be below 10 ng / L. However, traditional drinking water treatment processes have limited effectiveness in removing these odorous substances, making it difficult to meet water quality standards. The development of efficient removal technologies is urgently needed to address this problem.

[0003] Ozone / hydrogen peroxide advanced oxidation technology has good potential for removing odorous substances due to its ability to produce highly oxidizing hydroxyl radicals. However, its actual application effect is significantly affected by multiple factors such as pH value, ozone dosage, and hydrogen peroxide ratio. Currently, this technology still faces many challenges in practical application: on the one hand, the reaction conditions require strict control, and conventional processes are sensitive to pH and easily affect catalyst activity; on the other hand, the catalyst recycling efficiency is low, and traditional loading methods cannot guarantee its stability and activity. At the same time, it lacks adaptability to fluctuations in the concentration of odorous substances in the influent, and the optimal operating conditions and treatment effects still require further research and optimization.

[0004] Regarding the current problem of removing odorous substances from drinking water, although ozone / hydrogen peroxide advanced oxidation technology has shown application potential, problems such as low removal efficiency, limited operating conditions, and poor catalyst stability in traditional treatment processes need to be urgently addressed. There is an urgent need for a method for removing odorous substances that can effectively cope with different water quality conditions and improve treatment effects. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for removing odorous substances based on oxidation technology. By adjusting the raw water quality and using ozone, hydrogen peroxide, transition metal oxide catalysts and organic enhancers for synergistic oxidation, the removal rate of odorous substances can be effectively improved, the catalyst stability and recycling efficiency can be enhanced, the shortcomings of the existing technology in the removal of odorous substances can be solved, and the needs of meeting the standards for the treatment of odorous substances in drinking water can be met.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for removing odorous substances based on oxidation technology, comprising the following steps:

[0008] S1: Raw water quality adjustment: Adjust the 2-MIB concentration in the raw water and control the pH within a range that is conducive to the oxidation reaction. Stabilize the raw water concentration by adding reagents to provide a quantifiable treatment benchmark for subsequent processes. The stable 2-MIB concentration makes the process parameter debugging more accurate. After pH adjustment, the oxidation reaction rate increases by 20%-30%.

[0009] S2: Oxidation reaction treatment: The raw water is introduced into an oxidation device containing a reaction column, and ozone and hydrogen peroxide are added, and a transition metal oxide catalyst and an organic enhancer are added for synergistic oxidation; H2O2 acts as an initiator to accelerate the decomposition of O3 and produce active free radicals; the transition metal oxide catalyst promotes the decomposition of H2O2 through valence state cycling to generate more hydroxyl groups; at the same time, it adsorbs O3 molecules to reduce the activation energy of the reaction; the organic enhancer complexes with the metal ions to prevent hydroxide precipitation, broaden the reaction pH range, and produce additional active species through photolysis or thermal decomposition.

[0010] S3: Water purification: The oxidized water body is subjected to coagulation and sedimentation treatment to ensure that the water quality meets the standards.

[0011] In some feasible methods, in the raw water quality regulation, the 2-MIB inlet concentration is regulated by adding 2-MIB reagent, and the pH is regulated by sodium hydroxide solution, and the pH value is controlled at 7.0-7.5. This range can optimize the ozone self-decomposition rate, promote the generation of hydroxyl radicals, and avoid ozone decomposition too fast or too slow under excessively acidic or alkaline conditions.

[0012] In some feasible methods, the oxidation equipment includes several stainless steel reaction columns, and spoilers are installed in the reaction columns. The reaction time is controlled at 3-15 minutes. The spoilers enhance gas-liquid mixing through turbulence, which can increase the ozone mass transfer area, increase the mass transfer rate, and shorten the reaction time.

[0013] And / or, the ozone is generated by a generator with a switching function between an air source and an oxygen source, the gas source switching is automatically performed by an intelligent control system according to the ozone dosage concentration requirement, and the dosage is accurately controlled by a gas mass flow controller.

[0014] In some feasible embodiments, the transition metal oxide catalyst is at least one of MnO2, Fe2O3, and CuO, which is made into nano-scale particles and loaded on a porous carrier, and the porous carrier includes at least one of activated carbon, molecular sieve or alumina.

[0015] In some achievable methods, the catalyst is loaded by chemical bonding, and the specific steps are as follows:

[0016] Surface modification of porous supports: Use 5-10% acid anhydride or alcohol solution at 50-80°C for 2-4 hours to introduce carboxyl or hydroxyl groups; acid anhydride (such as phthalic anhydride) undergoes esterification reaction with the hydroxyl groups on the surface of activated carbon at 50-80°C to introduce carboxyl groups and provide reaction sites for covalent bonds.

[0017] Modification of catalyst nanoparticles: 5-15% amino reagent is added during the preparation process, the pH is adjusted to 8-9.5, and amino groups are grafted; the amino reagent (such as ethylenediamine) undergoes a condensation reaction with the hydroxyl groups on the surface of catalyst nanoparticles such as MnO2, grafting amino groups to form a positively charged surface, which is initially combined with the -COOH of the modified support through electrostatic attraction.

[0018] Chemical bonding: The modified carrier and modified nanoparticles are mixed in a mass ratio of 1:0.8-1:1.2 and reacted in an ethanol-water system at 80-100°C for 8-12 hours to form a covalent bond. In the ethanol-water system, the carrier's -COOH reacts with the particle's -NH2 through an amidation reaction, forming a covalent bond that significantly enhances the bonding strength compared to physical adsorption.

[0019] Through the above means, the catalyst loss rate in the present invention is small, and the catalytic efficiency still reaches 85% of the initial value after repeated use 200 times.

[0020] In some feasible methods, the organic enhancer is oxalic acid, tartaric acid or citric acid, which is prepared into a solution with a concentration of 0.1-10 g / L and added synchronously with hydrogen peroxide through a metering pump. The addition amount is controlled at 1-10 mg / L, and the addition time error does not exceed ±3%.

[0021] In some feasible approaches, mixing the two solutions of oxalic acid and tartaric acid at a mass ratio of 2:1-3:1 at 20-25°C with stirring at 200-300 rpm for 10-15 minutes to form a homogeneous solution, and adjusting the pH of the mixture to 5-6.5, can optimize the complexation constant, enhance metal ion chelation, and generate additional active species. Furthermore, the synergist and catalyst synergize to increase the hydroxyl yield by 30%, significantly accelerating the degradation rate of 2-MIB.

[0022] Oxalic acid and tartaric acid are mixed in a ratio of 2:1-3:1 and react with transition metal ions (such as Fe 3+ 、Mn 4+ ) forms a mixed ligand complex, increasing the stability constant by 12% and extending the upper pH limit for inhibiting metal hydroxide precipitation from 6.5 to 8.0, thus preventing the deactivation of catalyst active sites due to precipitation. The composite synergist in this invention inhibits metal ion dissolution through complexation, reducing the loss of active catalyst components. Furthermore, the synergist forms a protective layer on the catalyst surface, reducing the tendency of nanoparticles to agglomerate.

[0023] The traditional Fenton reaction needs to be run under strongly acidic conditions of pH < 3. However, after the composite synergist and catalyst in the present invention work together, the high-efficiency reaction range is extended to pH 7.0-7.5, avoiding the additional cost of acid and base adjustment.

[0024] In some feasible methods, in conventional water purification, polyaluminium chloride is added for coagulation, the dosage of polyaluminium chloride is 10-20 mg / L, and the flocculation hydraulic retention time is 20-60 min;

[0025] Alternatively, when the ozone dosage is ≥2 mg / L, add a silicone defoamer at a dosage of 5-10 mg / L to the flocculation tank. The dosage is controlled by a foam monitoring sensor. The defoamer disrupts the foam's surface tension, preventing the foam from carrying unreacted ozone or organic matter. The foam monitoring sensor controls the dosage to avoid overdosage. Furthermore, oxidation products (especially small organic molecules) are more easily flocculated by PAC, reducing coagulant usage by 10-20%. Combined with PAM, it can increase floc settling speed by 30-50%.

[0026] In some feasible methods, polyacrylamide is added as a coagulant during the coagulation process at a dosage of 0.05-0.2 mg / L. The dosage of polyacrylamide is adjusted according to the influent water quality using an automatic control system.

[0027] In some implementations, the operating parameters for different 2-MIB influent concentrations are as follows:

[0028] When the 2-MIB influent concentration is less than 50 ng / L: ozone dosage is 1.0-1.5 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.1-0.15:1, catalyst dosage is 0.1-0.3 g / L, and organic synergist dosage is 1-3 mg / L;

[0029] When the 2-MIB influent concentration is 50-100 ng / L: ozone dosage is 1.3-1.5 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.1-0.2:1, catalyst dosage is 0.3-0.5 g / L, and organic synergist dosage is 3-5 mg / L;

[0030] When the 2-MIB influent concentration is 100-200 ng / L: ozone dosage is 1.5-2.0 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.2-0.3:1, catalyst dosage is 0.5-0.6 g / L, and organic synergist dosage is 5-7 mg / L;

[0031] When the 2-MIB influent concentration is greater than 200 ng / L: ozone dosage is 2.5-4 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.3-0.4:1, catalyst dosage is 0.5-0.8 g / L, and organic synergist dosage is 7-10 mg / L.

[0032] This method adjusts the dosage of ozone and catalyst based on the influent 2-MIB concentration. When the influent 2-MIB concentration is high (>200 ng / L), the ozone dosage is increased to 3.0 mg / L. Combined with a high-dose catalyst, the ozone dosage rapidly degrades pollutants through its high free radical concentration and multiple catalytic sites. At low concentrations (<50 ng / L), the dosage of the ozone and catalyst is reduced to avoid excessive oxidation and increased costs. This dynamic matching ensures a 2-MIB removal rate of >95% under various water quality conditions, reducing operating costs by 10-15%.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The present invention stabilizes the raw water concentration by adding 2-MIB reagent and controls the pH at 7.0-7.5 with sodium hydroxide. The optimal rate of ozone self-decomposition to produce hydroxyl radicals in this range is utilized to avoid free radical quenching or ineffective ozone decomposition caused by excessive acidity or alkalinity, thereby significantly improving the degradation rate of 2-MIB in the subsequent oxidation stage and the reaction efficiency by 40%.

[0035] (2) In the present invention, ozone, hydrogen peroxide, transition metal catalyst and organic synergist constitute a four-level synergistic system. Through the synergistic effect of ozone and peroxide generating active free radicals, the catalyst accelerating the generation of free radicals, and the synergist maintaining the solubility of metal ions, the 2-MIB removal rate is increased from 60% of the single ozone process to more than 95%, the reaction time is shortened from 30 min to 3-15 min, and the ozone utilization rate is increased from 35% to 65%.

[0036] (3) The present invention uses anhydride-modified carriers to introduce carboxyl groups and amino-modified nanoparticles to graft amino groups. The catalyst is loaded on a porous carrier such as activated carbon through covalent bonding in an ethanol-water system. Compared with traditional physical loading, the catalyst loss rate is significantly reduced, the specific surface area is maintained at 220 m² / g, and the catalytic efficiency still reaches 85% of the initial value after repeated use 200 times.

[0037] (4) In the present invention, oxalic acid and tartaric acid are mixed in a ratio of 2:1-3:1 to form a composite ligand, which forms a mixed complex with the metal ions on the catalyst surface, inhibiting the formation of Fe(OH)3 and other precipitates, and widening the effective pH range of the traditional Fenton reaction from <3 to 7.0-7.5, thereby avoiding the additional cost of acid and base adjustment.

[0038] (5) The present invention adjusts the dosage of ozone and catalyst according to the concentration gradient of 2-MIB influent concentration, combines the intelligent switching of ozone source and the enhancement of mass transfer by spoiler, and when the influent concentration drops from 200 ng / L to 50 ng / L, the ozone dosage is reduced by 50%, the catalyst dosage is reduced by 60%, and the cost of treating a ton of water is reduced. At the same time, the removal rate in each concentration range is greater than 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the process flow of the method for removing odorous substances based on oxidation technology in the present invention;

[0040] Figure 2 This is the ozone concentration decay curve under different pH conditions (when the H2O2 / O3 mass ratio is 0.2). The horizontal axis is the reaction time (s), ranging from 0-600s, reflecting the progress of the oxidation reaction; the vertical axis is the ozone concentration (mg / L), reflecting the consumption and residual situation of ozone in the reaction; the figure contains 4 sets of data curves, corresponding to pH=7.17, 7.49, 8.00, and 8.50 conditions, showing the influence of different pH on the decay trend of ozone concentration over time. DETAILED DESCRIPTION

[0041] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0042] Example 1: This example provides a method for removing odorous substances based on oxidation technology, comprising the following steps:

[0043] S1: Raw water adjustment: The concentration of 2-MIB inlet water is adjusted by adding 2-MIB reagent. The pH is adjusted by sodium hydroxide solution and the pH value is controlled at 7.0-7.5. Please refer to Figure 2 As shown, Figure 2 The figure shows the ozone concentration attenuation trend after different pH values. It can be seen that when pH=8 and pH=8.5 before the reaction, the pH drop after the reaction is particularly obvious. This shows that a large number of hydroxyl radicals are generated in the reaction system at this time, and a part of NOM is oxidized into organic acids. At this time, there is an excessive amount of hydroxyl radicals, which is likely to cause the death of algae cells in the raw water, release intracellular substances and affect the subsequent coagulation process. Therefore, the pH in these two cases is too high, and it is not suitable to use a pH higher than 7.50 as a regulating parameter in actual engineering applications. Therefore, the pH value needs to be controlled within the range of 7.0-7.5. Specifically, in this embodiment, 10% NaOH solution is used to adjust the pH to 7.2.

[0044] S2: Oxidation reaction: The raw water is introduced into an oxidation device containing a reaction column, wherein the oxidation device comprises several stainless steel reaction columns, and a spoiler is set in the reaction column; specifically, Figure 1 As shown, in practice, the oxidation apparatus can be divided into four independent chambers, each of which houses a reaction column, such as reaction column 1#, reaction column 2#, reaction column 3#, and reaction column 4#. It will be appreciated that, depending on actual conditions, the number of advanced oxidation reaction chambers and reaction columns can be adjusted based on the amount of raw water to be treated.

[0045] Ozone and hydrogen peroxide are added to the oxidation equipment, and a transition metal oxide catalyst and an organic synergist are added for synergistic oxidation. The reaction time is controlled to be 5 minutes. The catalyst is MnO2 nanoparticles chemically bonded to activated carbon. The specific preparation method includes the following steps:

[0046] Surface modification of porous supports: Activated carbon was treated with 5% phthalic anhydride solution at 60 °C for 2 h to introduce carboxyl groups;

[0047] Catalyst nanoparticle modification: 8% ethylenediamine was added during the preparation process, the pH was adjusted to 8.5, and amino groups were grafted;

[0048] Chemical bonding: The modified carrier and the modified nanoparticles were mixed in a mass ratio of 1:0.9 and reacted in an ethanol and water system at 85°C for 8-12 hours to form a covalent bond.

[0049] In this embodiment, the organic synergist is prepared in a mass ratio of oxalic acid to tartaric acid of 2:1. The two solutions are mixed at 22° C. with a stirring speed of 200 rpm for 12 min. The pH is adjusted to 5.8 to prepare a 0.5 g / L solution. The solution is added synchronously with the hydrogen peroxide via a metering pump, with an addition time error of no more than ±3%.

[0050] In this embodiment, ozone is generated by a generator with the function of switching between air source and oxygen source. The gas source switching is automatically performed by an intelligent control system according to the ozone dosage concentration requirement, and the dosage is accurately controlled by a gas mass flow controller.

[0051] S3: Water Purification: The oxidized water is subjected to coagulation and sedimentation to ensure water quality meets standards. Specifically, in this embodiment, polyaluminum chloride (PAC) is added for coagulation at a dosage of 15 mg / L, and the flocculation hydraulic retention time is 30 minutes. When the ozone dosage is ≥ 2 mg / L, an organosilicon defoamer is added to the flocculation tank at a dosage of 8 mg / L. The dosage is controlled by a foam monitoring sensor.

[0052] Furthermore, in this embodiment, polyacrylamide as a coagulant aid is added during the coagulation process, with an addition amount of 0.1 mg / L. The addition of polyacrylamide is adjusted according to the influent water quality using an automatic control system.

[0053] Based on the above, in this embodiment, multiple groups of raw water were tested, and the 2-MIB influent concentration in different groups of raw water was adjusted. The following operating parameters were set according to the 2-MIB influent concentration in different groups:

[0054] When the 2-MIB influent concentration is less than 50 ng / L: ozone dosage is 1.2 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.1:1, catalyst dosage is 0.2 g / L, and organic synergist dosage is 2 mg / L;

[0055] When the 2-MIB influent concentration is 50-100 ng / L: ozone dosage is 1.4 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.15:1, catalyst dosage is 0.4 g / L, and organic synergist dosage is 4 mg / L;

[0056] When the 2-MIB influent concentration is 100-200 ng / L: ozone dosage is 1.8 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.2:1, the catalyst dosage is 0.5 g / L, and the organic synergist dosage is 5-7 mg / L;

[0057] When the 2-MIB influent concentration is greater than 200 ng / L: the ozone dosage is 3.0 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.3:1, the catalyst dosage is 0.6 g / L, and the organic synergist dosage is 8 mg / L.

[0058] The effluent 2-MIB removal rates of the above-mentioned groups of different 2-MIB influent concentrations all reached above 95%.

[0059] Example 2: The method for removing odorous substances based on oxidation technology in this example has the same basic steps as Example 1, except that:

[0060] S1: Raw water adjustment: The 2-MIB inlet concentration of the raw water is adjusted by adding 2-MIB reagent and adjusting the pH to 7.5 with 10% NaOH solution.

[0061] S2: Oxidation reaction: The raw water is introduced into an oxidation device containing a reaction column, wherein the oxidation device comprises several stainless steel reaction columns, and a spoiler is set in the reaction column. The reaction time is controlled to be 15 minutes.

[0062] In this embodiment, the catalyst is Fe2O3 nanoparticles chemically bonded to a molecular sieve, and the specific preparation method includes the following steps:

[0063] Surface modification of porous supports: molecular sieves were treated with 8% phthalic anhydride solution at 80 °C for 2 h to introduce carboxyl groups;

[0064] Catalyst nanoparticle modification: 15% ethylenediamine was added during the preparation process, the pH was adjusted to 9.5, and amino groups were grafted;

[0065] Chemical bonding: The modified carrier and the modified nanoparticles were mixed in a mass ratio of 1:1.2 and reacted in an ethanol and water system at 100°C for 8 h to form a covalent bond.

[0066] In this embodiment, the organic synergist is prepared at a mass ratio of oxalic acid to tartaric acid of 3:1. The two solutions are mixed at 25° C. with a stirring speed of 300 rpm for 15 min. The pH is adjusted to 6.5 to prepare a 10 g / L solution.

[0067] S3: Water Purification: The oxidized water is subjected to coagulation and sedimentation to ensure water quality meets standards. Specifically, in this embodiment, polyaluminum chloride is added for coagulation at a dosage of 20 mg / L and a flocculation hydraulic retention time of 20 minutes. When the ozone dosage is ≥ 2 mg / L, a silicone defoamer is added to the flocculation tank at a dosage of 10 mg / L.

[0068] Furthermore, in this embodiment, polyacrylamide as a coagulant aid is added during the coagulation process, with an addition amount of 0.2 mg / L. The addition of polyacrylamide is adjusted according to the influent water quality using an automatic control system.

[0069] Based on the above, in this embodiment, multiple groups of raw water were tested, and the 2-MIB influent concentration in different groups of raw water was adjusted. The following operating parameters were set according to the 2-MIB influent concentration in different groups:

[0070] When the 2-MIB influent concentration is less than 50 ng / L: ozone dosage is 1.0 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.1:1, catalyst dosage is 0.1 g / L, and organic synergist dosage is 1 mg / L;

[0071] When the 2-MIB influent concentration is 50-100 ng / L: ozone dosage is 1.3 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.2:1, catalyst dosage is 0.3 g / L, and organic synergist dosage is 3 mg / L;

[0072] When the 2-MIB influent concentration is 100-200 ng / L: ozone dosage is 1.5 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.3:1, the catalyst dosage is 0.6 g / L, and the organic synergist dosage is 5 mg / L;

[0073] When the 2-MIB influent concentration is greater than 200 ng / L: the ozone dosage is 2.5 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.4:1, the catalyst dosage is 0.5 g / L, and the organic synergist dosage is 7 mg / L.

[0074] The effluent 2-MIB removal rates of the above-mentioned multiple groups of different 2-MIB influent concentrations all reached above 98%.

[0075] Example 3: The method for removing odorous substances based on oxidation technology in this example has the same basic steps as Example 1, except that:

[0076] S1: Raw water adjustment: The 2-MIB inlet concentration of the raw water is adjusted by adding 2-MIB reagent and adjusting the pH to 7.0 with 10% NaOH solution.

[0077] S2: Oxidation reaction: The raw water is introduced into an oxidation device containing a reaction column, wherein the oxidation device comprises several stainless steel reaction columns, and a spoiler is set in the reaction column. The reaction time is controlled to be 3 minutes.

[0078] In this embodiment, the catalyst is CuO nanoparticles chemically bonded and loaded on activated carbon, and the specific preparation method includes the following steps:

[0079] Surface modification of porous supports: Activated carbon was treated with 10% phthalic anhydride solution at 50 °C for 4 h to introduce carboxyl groups;

[0080] Catalyst nanoparticle modification: 5% ethylenediamine was added during the preparation process, the pH was adjusted to 8.5, and amino groups were grafted;

[0081] Chemical bonding: The modified carrier and the modified nanoparticles were mixed in a mass ratio of 1:0.8 and reacted in an ethanol and water system at 90°C for 10 h to form a covalent bond.

[0082] In this embodiment, the organic synergist is prepared at a mass ratio of oxalic acid to tartaric acid of 2.5:1. The two solutions are mixed at 20° C. with a stirring speed of 260 rpm for 10 min. The pH is adjusted to 5 to prepare a 5 g / L solution.

[0083] S3: Water Purification: The oxidized water is subjected to coagulation and sedimentation to ensure that the water quality meets standards. Specifically, in this embodiment, polyaluminum chloride is added for coagulation at a dosage of 10 mg / L and a flocculation hydraulic retention time of 60 minutes. When the ozone dosage is ≥ 2 mg / L, a silicone defoamer is added to the flocculation tank at a dosage of 5 mg / L.

[0084] Furthermore, in this embodiment, a coagulant aid polyacrylamide is added during the coagulation process, with an addition amount of 0.05 mg / L.

[0085] Based on the above, in this embodiment, multiple groups of raw water were tested, and the 2-MIB influent concentration in different groups of raw water was adjusted. The following operating parameters were set according to the 2-MIB influent concentration in different groups:

[0086] When the 2-MIB influent concentration is less than 50 ng / L: ozone dosage is 1.4 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.15:1, catalyst dosage is 0.3 g / L, and organic synergist dosage is 3 mg / L;

[0087] When the 2-MIB influent concentration is 50-100 ng / L: ozone dosage is 1.5 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.2:1, catalyst dosage is 0.5 g / L, and organic synergist dosage is 5 mg / L;

[0088] When the 2-MIB influent concentration is 100-200 ng / L: ozone dosage is 2.0 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.25:1, the catalyst dosage is 0.5 g / L, and the organic synergist dosage is 7 mg / L;

[0089] When the 2-MIB influent concentration is greater than 200 ng / L: ozone dosage is 4.0 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.35:1, the catalyst dosage is 0.8 g / L, and the organic synergist dosage is 10 mg / L.

[0090] The effluent 2-MIB removal rates of the above-mentioned groups of different 2-MIB influent concentrations all reached above 95%.

[0091] Comparative Example 1: No catalyst was used in this comparative example, and no transition metal oxide catalyst was added in step S2 of this comparative example. The remaining parameters were the same as those in Example 1.

[0092] In this comparative example, multiple groups of raw water were tested, and the 2-MIB influent concentration in different groups of raw water was adjusted. The following operating parameters were set according to the 2-MIB influent concentration in different groups:

[0093] When the 2-MIB influent concentration is less than 50 ng / L: ozone dosage is 1.2 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.1:1, and the organic synergist dosage is 2 mg / L;

[0094] When the 2-MIB influent concentration is 50-100 ng / L: ozone dosage is 1.4 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.15:1, and the organic synergist dosage is 4 mg / L;

[0095] When the 2-MIB influent concentration is 100-200 ng / L: ozone dosage is 1.8 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.2:1, and the organic synergist dosage is 5-7 mg / L;

[0096] When the 2-MIB influent concentration is greater than 200 ng / L: the ozone dosage is 3.0 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.3:1, and the organic synergist dosage is 8 mg / L.

[0097] Comparative Example 2: In this comparative example, no organic synergist was used for oxidation treatment. In step S2 of this comparative example, no organic synergist was added, and the operating parameters were not adjusted according to the 2-MIB influent concentration in the raw water. A fixed addition value was adopted, i.e., an ozone dosage of 1.2 mg / L, hydrogen peroxide was added at a H2O2 / O3 mass ratio of 0.1:1, and a catalyst dosage of 0.2 g / L. The remaining parameters were the same as in Example 1.

[0098] Comparative Example 3: This comparative example uses a traditional physical supported catalyst without chemical bonding. Specifically, in step S2 of this comparative example, the catalyst adopts a physical supporting method, that is, MnO2 nanoparticles are directly adsorbed on the activated carbon, and the other parameters are the same as Example 1.

[0099] Comparative Example 4: This comparative example adopts the oxidation treatment of traditional unsupported catalyst. Specifically, the catalyst in step S2 of this comparative example adopts unsupported MnO2 powder, which is non-nanoscale, has a particle size of >1μm, and is not supported by a porous carrier. The other parameters are the same as those in Example 1.

[0100] Table 1 Comparison of performance parameters between examples and comparative examples

[0101]

[0102] As shown in Table 1 above, the ozone-hydrogen peroxide-catalyst-synergist quaternary synergy in Examples 1-3 of the present invention resulted in 2-MIB removal rates exceeding 95%, significantly improving over Comparative Examples 1-4. The synergistic effect of the catalyst and synergist increased the hydroxyl radical yield by 30% and reduced the reaction activation energy from 85 kJ / mol to 52 kJ / mol, demonstrating that the synergistic system of the present invention can overcome the efficiency bottleneck of traditional single oxidation technologies.

[0103] In Examples 1-3 of the present invention, chemically bonded catalyst loading was used, resulting in catalyst loss rates of less than 1%, a significant improvement over Comparative Example 3 (physical loading, 15.8%). The nanoscale catalyst, with a surface area of ​​220 m² / g, provides more active sites and maintains an efficiency of 85% after 200 reuses, compared to a 50% drop in efficiency after 20 reuses for the physically loaded catalyst.

[0104] The present invention targets high-concentration water (>200 ng / L) and achieves a removal rate of over 95% through the gradient addition of ozone and catalyst, significantly increasing the removal rate compared to the fixed-parameter operation in Comparative Example 4 while reducing costs. Furthermore, the spoiler enhances mass transfer, shortening the reaction time to 3-15 minutes, significantly improving the efficiency compared to conventional processes while also reducing the cost per ton of water.

[0105] In the absence of a catalyst (Comparative Example 1) or a synergist (Comparative Example 2), free radical generation decreased by 40%, and the removal rate decreased significantly. In Comparative Example 3, physical loading was used. Due to weak binding forces, the catalyst loss rate reached 15.8%, and the specific surface area dropped from 220 m² / g to below 100 m² / g, resulting in a significant decrease in removal rate compared to Example 1. Frequent catalyst replenishment was also required, increasing hidden costs.

[0106] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A method for removing odorous substances based on oxidation technology, characterized in that: The following steps are involved: S1: Raw water quality adjustment: adjust the concentration of 2-MIB in the raw water and control the pH to a range that is conducive to the oxidation reaction; S2: Oxidation reaction treatment: raw water is introduced into an oxidation device, ozone and hydrogen peroxide are added, and a transition metal oxide catalyst and an organic synergist are added simultaneously. The organic synergist is oxalic acid, tartaric acid or citric acid. The transition metal oxide catalyst is at least one of MnO2, Fe2O3 and CuO, which is made into nano-sized particles and loaded on a porous carrier; The catalyst is loaded by chemical bonding, and the specific steps are: Surface modification of porous supports: using 5-10% anhydride or alcohol solution at 50-80°C for 2-4 hours to introduce carboxyl or hydroxyl groups; Catalyst nanoparticle modification: add 5-15% amino reagent during the preparation process, adjust the pH to 8-9.5, and graft amino groups; Chemical bonding: The modified carrier and the modified nanoparticles are mixed in a mass ratio of 1:0.8-1:1.2 and reacted in an ethanol and water system at 80-100°C for 8-12 hours to form a covalent bond; S3: Water purification: The oxidized water body is subjected to coagulation and sedimentation treatment to ensure that the water quality meets the standards.

2. The method according to claim 1, characterized in that In the raw water quality adjustment, 2-MIB concentration adjustment is achieved by adding 2-MIB reagent, and pH adjustment is achieved by using sodium hydroxide solution, and the pH value is controlled to be 7.0-7.

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3. The method according to claim 1, characterized in that The oxidation equipment comprises several stainless steel reaction columns, each of which is provided with a spoiler, and the reaction time is controlled within 3-15 minutes; And / or, the ozone is generated by a generator with a switching function between an air source and an oxygen source, the gas source switching is automatically performed by an intelligent control system according to the ozone dosage concentration requirement, and the dosage is accurately controlled by a gas mass flow controller.

4. The method according to claim 1, wherein The porous carrier is at least one of activated carbon, molecular sieve and alumina.

5. The method according to claim 1, characterized in that The organic synergist is prepared into a solution with a concentration of 0.1-10 g / L, and is added synchronously with the hydrogen peroxide through a metering pump, with an addition time error not exceeding ±3%.

6. The method according to claim 5, characterized in that According to the mass ratio of oxalic acid to tartaric acid of 2:1-3:1, the two solutions were mixed at 20-25°C, with a stirring speed of 200-300 rpm and a mixing time of 10-15 minutes to form a uniform solution, and the pH value of the mixed solution was adjusted to 5-6.

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7. The method according to claim 1, characterized in that In the water purification treatment, polyaluminium chloride is added for coagulation, the dosage of polyaluminium chloride is 10-20 mg / L, and the flocculation hydraulic retention time is 20-60 min; And / or, when the ozone dosage is ≥2 mg / L, add an organosilicon defoamer in the flocculation tank at a dosage of 5-10 mg / L, and control the dosage through a foam monitoring sensor.

8. The method according to claim 7, characterized in that In step S3, polyacrylamide is added as a coagulant during the coagulation process, with an addition amount of 0.05-0.2 mg / L. The addition of polyacrylamide is adjusted according to the influent water quality using an automatic control system.

9. The method according to claim 1, characterized in that The operating parameters for different 2-MIB influent concentrations are as follows: When the 2-MIB influent concentration is less than 50 ng / L: ozone dosage is 1.0-1.5 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.1-0.15:1, catalyst dosage is 0.1-0.3 g / L, and organic synergist dosage is 1-3 mg / L; When the 2-MIB influent concentration is 50-100 ng / L: ozone dosage is 1.3-1.5 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.1-0.2:1, catalyst dosage is 0.3-0.5 g / L, and organic synergist dosage is 3-5 mg / L; When the 2-MIB influent concentration is 100-200 ng / L: ozone dosage is 1.5-2.0 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.2-0.3:1, catalyst dosage is 0.5-0.6 g / L, and organic synergist dosage is 5-7 mg / L; When the 2-MIB influent concentration is greater than 200 ng / L: ozone dosage is 2.5-4 mg / L, hydrogen peroxide is added at a H2O2 / O3 mass ratio of 0.3-0.4:1, catalyst dosage is 0.5-0.8 g / L, and organic synergist dosage is 7-10 mg / L.

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