Method for degrading odor substances in water by synergistically catalyzing ozone through ultraviolet hydrogen peroxide

Abstract

The invention relates to the technical field of water treatment, and discloses a method for degrading odor substances in water by synergistically catalyzing ozone with ultraviolet hydrogen peroxide, which comprises the following steps: firstly, carrying out precision filtration on raw water to reduce turbidity, and then pumping ozone under set pressure to realize pressurized dissolved gas; the method comprises the key steps that isobaric gas phase separation is carried out under the condition that the system pressure is kept unchanged, undissolved free bubbles are physically removed, and ozone-saturated homogeneous transparent fluid is obtained; and then hydrogen peroxide is rapidly injected through a pipeline mixer, the mixed fluid is introduced into a photocatalytic reactor, and a synergistic reaction is carried out by utilizing ultraviolet irradiation in a pressure maintaining state. The high-pressure optical homogeneous fluid environment is constructed, the scattering and shielding effects of bubbles in gas-liquid two-phase flow on ultraviolet light are eliminated, high-concentration hydroxyl free radicals are generated through high-pressure enriched dissolved ozone and hydrogen peroxide under ultraviolet excitation, and deep mineralization of 2-MIB, GSM and other degradation-resistant odor substances is achieved.

Description

Technical Field

[0001] This invention relates to the field of water treatment technology, specifically to a method for the degradation of odorous substances in water by ultraviolet hydrogen peroxide synergistically catalyzing ozone. Background Technology

[0002] In recent years, intensified industrial and agricultural activities have led to a growing pollution load on surface water bodies. Particularly affected by the greenhouse effect and localized extreme weather events, eutrophication of water bodies is frequent, and odor-causing substances such as geosmin (GSM) and dimethylisoborneol (2-MIB) produced by the metabolism of cyanobacteria and other microorganisms have become major threats to drinking water safety. Furthermore, novel trace organic pollutants such as pesticides and antibiotics are frequently detected in water sources. These pollutants typically possess stable chemical structures and extremely low odor thresholds, making them difficult to remove deeply using conventional coagulation, sedimentation, and filtration processes. To address this challenge, advanced oxidation technologies based on the generation of highly reactive hydroxyl radicals, particularly the ozone-ultraviolet-hydrogen peroxide synergistic system, have been widely applied in the mineralization treatment of recalcitrant organic pollutants due to their broad-spectrum oxidation capabilities.

[0003] In existing ozone-UV synergistic catalytic processes, reaction efficiency is constrained by both gas-liquid mass transfer and light transport mechanisms. Due to the limited solubility of ozone in water, conventional processes typically employ aeration or gas-liquid mixing pumps to continuously introduce ozone-containing gas into the reactor, resulting in a gas-liquid two-phase mixture in the reaction fluid. In this heterogeneous system, the numerous undissolved microbubbles exert strong scattering and refraction on UV light, creating a significant light-shielding effect. This not only hinders the effective transmission of UV photons into the deeper liquid phase, reducing light energy utilization, but also limits the rate at which ozone photolysis generates hydroxyl radicals, leading to unstable degradation efficiency for odor-causing substances and emerging pollutants.

[0004] The synergistic effect of multi-component oxidants places extremely high demands on the control of reaction conditions. In practical engineering applications, if the mixing process of hydrogen peroxide and ozone lacks precise control, a non-photocatalytic dark reaction will occur before they enter the ultraviolet radiation region, resulting in the ineffective consumption of the oxidant without the generation of free radicals. Simultaneously, for raw water containing bromide ions, the highly oxidizing ozone readily oxidizes bromide ions into the carcinogenic byproduct bromate. Existing technologies often struggle to effectively balance the economical utilization rate of the oxidant with the suppression and control of bromate byproducts while ensuring high-intensity oxidation and removal of organic pollutants, thus limiting the widespread application of this process in complex water treatment. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for the synergistic degradation of odorous substances in water by ultraviolet hydrogen peroxide and ozone. This method solves the problems in existing ozone-hydrogen peroxide-ultraviolet advanced oxidation processes, such as limited mass transfer of ozone liquid and scattering and shielding of ultraviolet light by undissolved bubbles, resulting in low hydroxyl radical yield, incomplete mineralization of odorous substances, and easy formation of bromate byproducts.

[0006] To achieve the above objectives, the present invention provides a method for the synergistic degradation of odor-causing substances in water by ultraviolet hydrogen peroxide and ozone, which eliminates the bubble light-shielding effect and enhances the free radical yield by constructing a high-pressure optical homogeneous fluid environment, comprising the following steps: S1. Raw water pretreatment: Filter raw water containing odorous substances to reduce water turbidity and thus reduce the scattering of light by suspended particles. S2, Ozone pressurized dissolved air: The pretreated water is pumped into the dissolved air system, and ozone is introduced under a set pressure P1, so that the ozone exists in the water in a dissolved state. S3, Isobaric gas phase separation: Under the condition of maintaining the system pressure P1 without decreasing, the gas-liquid mixture is separated to remove undissolved free gas bubbles and obtain a homogeneous transparent fluid that is saturated or supersaturated with ozone. S4. Establishing the reaction system: Inject hydrogen peroxide solution into the above homogeneous transparent fluid, using hydrogen peroxide as a co-catalyst and chain reaction initiator; S5, Pressure-maintaining synergistic reaction: The mixed fluid is introduced into the photocatalytic reactor, and the pressure inside the reactor is maintained at P1. Under ultraviolet light irradiation, dissolved ozone and hydrogen peroxide are used to synergistically generate hydroxyl radicals to mineralize and degrade odor substances.

[0007] By employing the above technical solution, this invention utilizes pressurized dissolved gas to enhance the saturated solubility and mass transfer driving force of ozone in the aqueous phase. The core of this solution lies in isobaric gas-phase separation, that is, while maintaining high pressure to prevent the precipitation of dissolved ozone, undissolved gaseous ozone is removed through physical separation. This step eliminates the scattering and shielding effect of microbubbles on ultraviolet light in the gas-liquid two-phase flow, making the reaction fluid an optically homogeneous medium, thereby significantly improving the transmission efficiency of ultraviolet light in the liquid phase. Under the synergistic conditions of high concentration of dissolved ozone, hydrogen peroxide, and high transmittance, the generation rate of hydroxyl radicals in the reaction system is greatly enhanced, achieving efficient mineralization of odor substances.

[0008] Preferably, in step S2, the pressure P1 is set to a range of 0.20 MPa to 0.40 MPa; and the concentration of dissolved ozone is controlled to be 1.0 mg / L to 5.0 mg / L.

[0009] By adopting the above technical solution, the system pressure is maintained between 0.20 MPa and 0.40 MPa, which can significantly increase the solubility of ozone according to Henry's Law, and make the oxidant reserve in the water reach several times that under normal pressure conditions. At the same time, this pressure range can avoid the increase in energy consumption caused by excessive pressure and the severe cavitation effect during subsequent depressurization.

[0010] Preferably, in step S3, the residence time for isobaric gas phase separation is 1.5 to 3.0 minutes; after separation, the relative ultraviolet light transmittance of the fluid in the reactor of step S5 is maintained above 95%.

[0011] By adopting the above technical solution and setting a residence time of 1.5 to 3.0 minutes, the gas-liquid density difference is used to allow the microbubbles to float to the surface and be discharged, ensuring that the fluid entering the photoreactor does not contain visible bubbles. This ensures that ultraviolet light energy is directly absorbed by the reactants in the liquid phase, avoiding light energy loss due to reflection or scattering at the bubble interface.

[0012] Preferably, in step S4, the concentration of hydrogen peroxide added to the water sample is from 7.0 mg / L to 20.0 mg / L. In this invention, the mass ratio of hydrogen peroxide to ozone is preferably from 2:1 to 10:1, more preferably from 2:1 to 7:1.

[0013] By adopting the above technical solution, within this mass ratio range, hydrogen peroxide mainly exists as HO2. - This process triggers a chain reaction, inducing the rapid decomposition of ozone to generate hydroxyl radicals. Controlling this ratio can balance the generation and consumption of free radicals, preventing excessive hydrogen peroxide from reacting with hydroxyl radicals and reducing oxidation efficiency.

[0014] Preferably, for raw water with a bromide ion background concentration higher than 100 μg / L, the mass ratio of hydrogen peroxide to dissolved ozone in step S4 is controlled to be no less than 4.5:1.

[0015] By employing the above technical solution, the reducing properties of hydrogen peroxide are utilized to suppress the formation of byproducts. In high-bromine water, the intermediate product (hypobromic acid / hypobromate ion) generated by ozone oxidation of bromide ions is a precursor to the carcinogen bromate. Maintaining a high concentration of hydrogen peroxide can rapidly reduce hypobromic acid to bromide ions, thereby cutting off the bromate formation pathway and ensuring the safety of the effluent.

[0016] Preferably, for raw water with a total organic carbon content higher than 3.0 mg / L, the set pressure P1 is adjusted to 0.35 MPa to 0.45 MPa in step S2, and the amount of hydrogen peroxide added is increased simultaneously in step S4 to maintain the mass ratio of hydrogen peroxide to dissolved ozone at 4:1 to 5:1.

[0017] By adopting the above technical solution, in response to the competitive consumption of oxidants by water bodies with high organic loads, the absolute amount of dissolved ozone is increased by increasing the system pressure, and the amount of hydrogen peroxide added is adjusted simultaneously to maintain a high free radical flux, ensuring that the removal rate of recalcitrant odor substances is not reduced by background organic matter.

[0018] Preferably, in step S5, the ultraviolet radiation intensity is 6.5 mW / cm². 2 Up to 7.5mW / cm 2 The hydraulic residence time is 20 to 40 minutes; the dominant wavelength of ultraviolet light is 253.7 nm.

[0019] By adopting the above technical solution, the photon energy of 253.7nm ultraviolet light is used to directly break the chemical bond between ozone and hydrogen peroxide, forming a dual free radical generation mechanism of photolysis and chemical catalysis.

[0020] Preferably, in step S4, the specific method for establishing the reaction system is as follows: a pipe mixer is set in the inlet pipe of the photocatalytic reactor, and hydrogen peroxide solution is injected online under pressure. The mixing time is controlled within 5 seconds, and then the system enters the ultraviolet radiation region of step S5.

[0021] By adopting the above technical solution, the reagents can be mixed instantaneously using a pipeline mixer, and the mixing time can be limited to less than 5 seconds. This avoids the ineffective consumption of the two oxidants under no-light conditions (dark reaction) and ensures that the reactants maintain the highest activity concentration when entering the photoreaction zone.

[0022] Preferably, in step S1, the filtration process includes passing the water through a sand filter column and a precision filter in sequence to control the turbidity of the effluent to be less than 0.5 NTU, preferably less than 0.2 NTU.

[0023] By adopting the above technical solution, the physical blocking of ultraviolet light by suspended particulate matter is minimized by strictly controlling the turbidity of the influent, and the subsequent bubble removal step is combined to ensure the efficiency of the photochemical reaction.

[0024] Preferably, the method further includes a post-treatment step S6: the reaction effluent from step S5 is depressurized by a back pressure valve and then passes through a granular activated carbon adsorption column, with an empty bed contact time of 10 to 15 minutes.

[0025] By adopting the above technical solution, the surface catalytic properties of activated carbon are used to quench residual hydrogen peroxide and adsorb and remove trace amounts of incompletely mineralized organic byproducts.

[0026] Furthermore, to ensure the accuracy of the measurements and the repeatability of the data for each parameter in the technical solution of this invention, the performance parameters involved in this specification are measured using the following methods: the concentration of liquid ozone is measured using the sodium indigo disulfonate spectrophotometric method (detection wavelength 610 nm); the concentrations of bromide ions and bromate are detected using the ion chromatography-suppressed conductivity method; the concentration of hydrogen peroxide is determined using the potassium oxalate colorimetric method; and the concentrations of odor substances (2-MIB and GSM) are quantitatively analyzed using gas chromatography-mass spectrometry (GC-MS).

[0027] This invention provides a method for the degradation of odor-causing substances in water by ultraviolet hydrogen peroxide and co-catalyzed ozone. It has the following beneficial effects: 1. This invention physically removes undissolved gaseous ozone bubbles by performing isobaric gas-phase separation after high-pressure dissolution, while maintaining the system pressure and dissolved ozone concentration. This measure eliminates the scattering and shielding effect of ultraviolet light at the bubble interface in the gas-liquid two-phase flow, constructs an optically homogeneous reactive fluid environment, significantly improves the transmission efficiency of ultraviolet light in the liquid phase and the photon utilization rate, thereby enhancing the generation rate of hydroxyl radicals.

[0028] 2. This invention achieves instantaneous and uniform mixing of hydrogen peroxide and high-concentration ozone water by installing a pipe mixer at the inlet of the photoreactor and controlling the mixing time to within 5 seconds. This method effectively suppresses the ineffective dark reaction consumption of the two oxidants under light-free conditions, ensuring that the oxidants are at their highest active concentration when entering the ultraviolet radiation region. It utilizes the dual mechanisms of photolysis and chemocatalysis to synergistically degrade recalcitrant odor substances such as 2-MIB and GSM.

[0029] 3. This invention constructs a reducing inhibition mechanism for water with high bromide ion background by adjusting the mass ratio of hydrogen peroxide to dissolved ozone. When the mass ratio is controlled above 4.5:1, the reducing properties of hydrogen peroxide are used to rapidly reduce hypobromic acid, an intermediate product of ozone oxidation, to bromide ions. This ensures the removal of organic pollutants while blocking the formation pathway of the carcinogenic byproduct bromate, thus improving the safety of the effluent. Attached Figure Description

[0030] Figure 1 Figure 1 is a comparison chart of measured photophysical parameters in the reaction system of the present invention. Figure 2(a) is a bar chart comparing the effective ultraviolet radiation irradiance inside the reactor under different process conditions, and Figure 3(b) is a bar chart comparing the relative light intensity transmission rate of the reaction system under different process conditions. Figure 2 This is a comparison chart showing the trend of cumulative hydroxyl radical concentration changing with reaction time in an embodiment of the present invention; Figure 3 This is a bar chart comparing the depth removal rates of two typical odor substances in an embodiment of the present invention. Figure 4 Figure 1 shows the degradation kinetics analysis of 2-MIB in an embodiment of the present invention. Figure 2(a) is a graph showing the change of normalized concentration of 2-MIB over time, and Figure 2(b) is a comparison graph showing the fitting of the pseudo-first-order kinetic model of 2-MIB degradation. Figure 5 This is a bar chart comparing the concentration of bromate formation in effluent under a high bromide ion background with the national standard limit, according to an embodiment of the present invention. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0033] Hydrogen peroxide solution, also known as hydrogen peroxide in Chinese, has the molecular formula H2O2 and CAS number 7722-84-1. In this example, an analytical grade reagent with a mass fraction of 30% is selected. It is diluted according to the experimentally set concentration before use and serves as the core oxidant in the synergistic oxidation system.

[0034] 2-Methylisoborneol, abbreviated as 2-MIB, has the molecular formula C 11 H 20 O, CAS No. 2371-42-8, purity ≥98%, standard, used to prepare simulated raw water containing odorous substances, as one of the target pollutants for degradation in this invention.

[0035] Geosmin, abbreviated as GSM, has the molecular formula C 12 H 22 O, CAS No. 19700-21-1, purity ≥98%, standard, used to prepare simulated raw water containing odorous substances, as one of the target pollutants for degradation in this invention.

[0036] Granular activated carbon, CAS No. 7440-44-0, coal-based granular form, particle size range 0.8~2.0mm, iodine adsorption value ≥950mg / g, methylene blue adsorption value ≥180mg / g, used in post-reaction treatment units to adsorb residues and catalytically decompose hydrogen peroxide.

[0037] Humic acid, CAS No. 1415-93-6, is a powder used to adjust the background value of total organic carbon (TOC) and ultraviolet absorbance in simulated raw water to simulate the shielding effect of dissolved organic matter on ultraviolet light in natural water bodies.

[0038] Sodium bromide, molecular formula NaBr, CAS number 7647-15-6, analytical grade, was used to adjust the background bromide ion concentration in simulated raw water to investigate the inhibitory effect of the process of this invention on the formation of the byproduct bromate in bromine-rich water.

[0039] Preparation Example 1: This preparation example provides a method for preparing standard simulated odor-containing raw water A to be treated, including the following steps: Deionized water was used as the matrix, and sodium bicarbonate and potassium dihydrogen phosphate were added to adjust the pH to 7.5±0.2, and the total alkalinity was adjusted to 100±5 mg / L (calculated as CaCO3) to simulate the buffer system of conventional drinking water source water. A certain volume of 2-MIB and GSM standard stock solutions (prepared with methanol as solvent) was measured and injected into the above water body through a microsyringe, and stirred vigorously for 30 minutes to ensure uniform mixing. The initial concentrations of 2-MIB and GSM in the final water sample were controlled to be 100±5 ng / L and 100±5 ng / L respectively, using gas chromatography-mass spectrometry (GC-MS). The turbidity of the prepared water sample was measured to be 0.1-0.2 NTU, and it was stored as a standard low-turbidity raw water in a light-proof, temperature-controlled container for later use.

[0040] Preparation Example 2: This preparation example provides a method for preparing simulated raw water B rich in bromide ions, including the following steps: Based on the standard simulated water body prepared in Preparation Example 1, analytical grade sodium bromide aqueous solution was added to the water sample. The bromide ion concentration (Br₂) in the water sample was controlled through calculation and detection. - The background concentration reached 200 ± 10 μg / L. Other water quality parameters, including pH, alkalinity, and the initial concentrations of 2-MIB and GSM, remained consistent with those of Preparation Example 1. This water sample was used to investigate its inhibitory effect on the formation of the carcinogenic byproduct bromate under different process conditions in subsequent tests.

[0041] Preparation Example 3: This preparation example provides a method for preparing raw water C containing high background organic matter and odor-causing substances, including the following steps: Based on the standard simulated water prepared in Example 1, a humic acid stock solution filtered through a 0.45 μm microporous membrane was added to the water sample. After thorough mixing, the total organic carbon (TOC) content of the water sample was measured and adjusted to 4.0 ± 0.2 mg / L, and its ultraviolet absorbance (UV absorbance) was measured simultaneously. 254 The value is 0.10 ± 0.01 cm. -1 This water sample was used to simulate the complex conditions under which dissolved organic matter (DOM) in natural surface water shields ultraviolet light and competitively consumes oxidants. Example

[0042] This embodiment provides a method for the synergistic degradation of odor substances in water by ultraviolet hydrogen peroxide and ozone, aiming to demonstrate the optimal treatment effect of the present invention under preferred process parameters, including the following steps: (1) Raw water pretreatment: Take the standard simulated raw water A prepared in Preparation Example 1 and pass it through a sand filter column and a PP cotton precision filter with a pore size of 1.0 μm in sequence to remove suspended impurities and control the turbidity of the effluent to be less than 0.2 NTU.

[0043] (2) Ozone pressurized dissolved air: The pretreated water is pumped into a 316L stainless steel pressurized dissolved air mixer, and the absolute pressure of the system is controlled at 0.30MPa. At the same time, ozone gas is introduced and the contact time is controlled at 45 seconds to make the dissolved ozone concentration in the water reach 2.0mg / L.

[0044] (3) Isobaric gas-liquid separation: The above gas-liquid mixture is transported to a pressure-resistant gas-liquid separator and held for 2.0 minutes while maintaining a system pressure of 0.30 MPa. Undissolved free ozone bubbles are separated and discharged using buoyancy, resulting in a supersaturated homogeneous ozone fluid without visible bubbles. Testing shows that the transmittance of the separated homogeneous fluid to 254 nm ultraviolet light remains above 95%, effectively eliminating the shielding effect of bubble scattering on light energy.

[0045] (4) Establishing the reaction system: Inject hydrogen peroxide solution into the reactor inlet pipe, and achieve instantaneous uniform mixing of the reagent and water under pressure by using a static mixer connected in series on the pipeline. The mixing time is controlled within 5 seconds (approximately 3 seconds in actual measurement), and the concentration of hydrogen peroxide in the water sample is controlled at 8.0 mg / L. At this time, the mass ratio of hydrogen peroxide to ozone is 4:1.

[0046] (5) Pressure-maintaining synergistic reaction: The mixed solution is introduced into the pressure-resistant photocatalytic reactor, and the pressure inside the reaction chamber is maintained at 0.30 MPa by controlling the back pressure valve. The ultraviolet lamp is turned on, and the intensity of ultraviolet radiation received by the water body is controlled to be 6.8 mW / cm². 2 The hydraulic residence time is 30 minutes. During this period, ultraviolet light, hydrogen peroxide, and dissolved ozone work together to generate hydroxyl radicals that degrade odor substances.

[0047] (6) Post-treatment: After the reaction effluent is depressurized by the back pressure valve, it passes through an adsorption column filled with coal-based granular activated carbon. The empty bed contact time is 12 minutes to quench residual hydrogen peroxide and adsorb trace amounts of by-products. Example 1

[0048] This embodiment provides a method for the synergistic degradation of odor substances in water by ultraviolet hydrogen peroxide and ozone, aiming to verify the operational effectiveness of the invention under low energy consumption and low reagent dosage conditions, and to support the lower limit of the scope of the claims. The method includes the following steps: (1) Raw water pretreatment: Same as in Example 1, treat raw water A.

[0049] (2) Ozone pressurized dissolved gas: Adjust the absolute pressure of the system to 0.20 MPa. Control the ozone dosage to make the dissolved ozone concentration in the water 1.0 mg / L.

[0050] (3) Isobaric gas phase separation: gas-liquid separation is carried out under constant pressure of 0.20MPa, residence time is 1.5 minutes, and macroscopic bubbles are removed.

[0051] (4) Establishing the reaction system: Inject hydrogen peroxide solution and control the concentration of hydrogen peroxide to be 7.0 mg / L. At this time, the mass ratio of hydrogen peroxide to ozone is 7:1.

[0052] (5) Pressure-maintaining synergistic reaction: The pressure inside the reactor was maintained at 0.20 MPa. The ultraviolet radiation intensity was controlled at 6.5 mW / cm². 2 The hydraulic residence time is 20 minutes.

[0053] (6) Post-treatment: After the reaction effluent is depressurized by the back pressure valve, it passes through an adsorption column filled with coal-based granular activated carbon. The empty bed contact time is 12 minutes to quench residual hydrogen peroxide and adsorb trace amounts of by-products. Example 2

[0054] This embodiment provides a method for the degradation of odor substances in water by ultraviolet hydrogen peroxide and co-catalytic ozone, using raw water C with high background organic matter prepared in Example 3, aiming to verify the high-intensity treatment capacity of the system under high pollution load conditions, supporting the upper limit of the scope of the claims, and including the following steps: (1) Raw water pretreatment: The raw water C prepared in Preparation Example 3 was pretreated by filtration, and the turbidity of the effluent was controlled below 0.5 NTU.

[0055] (2) Ozone pressurized dissolved gas: The absolute pressure of the system is adjusted to 0.40 MPa to overcome the competition of organic matter and improve the driving force of ozone mass transfer. The concentration of dissolved ozone in the water reaches 5.0 mg / L.

[0056] (3) Isobaric gas phase separation: Gas-liquid separation is carried out under constant pressure of 0.40MPa with a residence time of 3.0 minutes.

[0057] (4) Establish the reaction system: Increase the amount of hydrogen peroxide added and control its concentration in the water sample to 20.0 mg / L. At this time, the mass ratio of hydrogen peroxide to ozone is 4:1.

[0058] (5) Pressure-maintaining synergistic reaction: Maintain the reactor pressure at 0.40 MPa. Increase the UV lamp power and control the radiation intensity at 7.2 mW / cm². 2 Extend the hydraulic retention time to 40 minutes to ensure the full mineralization of recalcitrant organic matter.

[0059] (6) Post-treatment: After the reaction effluent is depressurized by the back pressure valve, it passes through an adsorption column filled with coal-based granular activated carbon. The empty bed contact time is 12 minutes to quench residual hydrogen peroxide and adsorb trace amounts of by-products. Example 3

[0060] This embodiment provides a method for the synergistic degradation of odor substances in water by ultraviolet hydrogen peroxide and ozone, aiming to investigate the influence of different pressure parameters on the reaction system and verify the rationality of the pressure range, including the following steps: (1) Raw water pretreatment: Same as in Example 1, treat raw water A.

[0061] (2) Ozone pressurized dissolved gas: Set the absolute pressure of the system to 0.25 MPa. Control the concentration of dissolved ozone in the water to 2.0 mg / L (consistent with Example 1, only the system pressure is changed).

[0062] (3) Isobaric gas phase separation: the bubbles are separated under a constant pressure of 0.25 MPa and the residence time is 2.0 minutes.

[0063] (4) Establish the reaction system: inject hydrogen peroxide solution and control the concentration to 8.0 mg / L.

[0064] (5) Pressure-maintaining synergistic reaction: The pressure inside the reactor was maintained at 0.25 MPa. The ultraviolet radiation intensity was controlled at 6.8 mW / cm². 2 The hydraulic residence time is 30 minutes.

[0065] (6) Post-processing: Same as in Example 1. Example 4

[0066] This embodiment provides a method for the synergistic degradation of odor substances in water by ultraviolet hydrogen peroxide and ozone, using bromine-rich raw water B prepared in Preparation Example 2. The aim is to verify the inhibitory effect of high-concentration hydrogen peroxide on the formation of the carcinogenic byproduct bromate, and includes the following steps: (1) Raw water pretreatment: The raw water B prepared in Preparation Example 2 was subjected to filtration pretreatment.

[0067] (2) Ozone pressurized dissolved gas: The absolute pressure of the control system is 0.30 MPa, so that the concentration of dissolved ozone is 2.0 mg / L.

[0068] (3) Isobaric gas phase separation: Remove bubbles under constant pressure of 0.30 MPa.

[0069] (4) Establishing the reaction system: In order to enhance the inhibition of bromate formation, the concentration of hydrogen peroxide was controlled at 9.0 mg / L (slightly higher than in Example 1). At this time, the mass ratio of hydrogen peroxide to ozone was 4.5:1, and an excess of hydrogen peroxide was used to construct a strong reducing barrier.

[0070] (5) Pressure-maintaining synergistic reaction: The pressure inside the reactor was maintained at 0.30 MPa. The ultraviolet radiation intensity was controlled at 6.8 mW / cm². 2 The hydraulic residence time is 30 minutes.

[0071] (6) Post-treatment: After the reaction effluent is depressurized by the back pressure valve, it passes through an adsorption column filled with coal-based granular activated carbon. The empty bed contact time is 12 minutes to quench residual hydrogen peroxide and adsorb trace amounts of by-products.

[0072] Comparative Example 1: This comparative example provides a conventional atmospheric pressure aeration photocatalytic oxidation method. Compared with Example 1, the difference is that the pressurization operation in step (2) and the gas-liquid separation operation in step (3) are omitted. The operating mode of continuously blowing ozone gas directly into the bottom of the atmospheric pressure photocatalytic reactor is adopted, keeping the total amount of ozone added consistent with Example 1. There are a large number of visible rising bubbles in the reactor, and the remaining steps and parameters are the same.

[0073] Comparative Example 2: This comparative example provides a treatment method of "pressurized gas dissolution followed by depressurized reaction". Compared with Example 1, the difference is that a depressurization operation is added between steps (3) and (4) to release the pressure of the dissolved water to atmospheric pressure, and then it enters a non-pressure-resistant ordinary photocatalytic reactor for reaction. At this time, the water is observed to be milky white (a large number of microbubbles are released); and the reaction water in step (6) does not pass through the back pressure valve for depressurization, but directly enters the activated carbon adsorption column, and the other raw materials and dosages are the same.

[0074] Comparative Example 3: This comparative example provides a UV / O3 pressurized treatment method without the addition of hydrogen peroxide. Compared with Example 5 (bromine-rich raw water condition), the difference is that the hydrogen peroxide injection operation in step (4) is cancelled, and degradation is carried out solely by ultraviolet photocatalysis of ozone; all other aspects are the same.

[0075] Comparative Example 4: This comparative example provides a UV / H2O2 pressurized treatment method without ozone addition. Compared with Example 1, the difference is that the ozone dissolution process in steps (2) and (3) is omitted, and the raw water is directly fed into the pressurized photoreactor after adding only the same concentration of hydrogen peroxide. All other aspects are the same.

[0076] Comparative Example 5: This comparative example provides a synergistic treatment method with a low hydrogen peroxide ratio. Compared with Example 5 (bromine-rich raw water condition), the difference is that the concentration of hydrogen peroxide added in step (4) is reduced to 1.5 mg / L (close to the traditional stoichiometric ratio), while the rest are the same.

[0077] Test Example 1: Actual Measurement of Ultraviolet Light Transmittance and Effective Irradiance of the Reaction System Experimental steps: (1) Detection platform construction: A 316L stainless steel photocatalytic reactor with the same specifications as in Example 1 was selected. A quartz window was opened in the middle section of the side wall of the reactor, and an online ultraviolet radiometer (model: UV-254-online) was installed. The probe surface was flush with the inner wall of the reactor to monitor the intensity of ultraviolet radiation that actually reaches the edge of the liquid phase inside the reaction chamber in real time.

[0078] (2) Determination of reference value: Under the condition that no gas is introduced and no chemical reagents are added, deionized water (turbidity < 0.1 NTU) is filled into the reactor, and the ultraviolet lamp is turned on to preheat for 10 minutes until the light intensity is stable. The irradiance value at this time is recorded as I0, which is used as the theoretical maximum light transmittance reference under the geometry of the reactor.

[0079] (3) Group test run: Test Group A (corresponding to Example 1): The system was operated according to the process parameters set in Example 1. The system maintained a pressure of 0.30 MPa and entered the reactor after isobaric gas-liquid separation.

[0080] Test Group B (Comparative Example 1): The system was operated according to the process parameters set in Comparative Example 1, and ozone was continuously blown into the reactor under normal pressure.

[0081] Test Group C (comparison to Comparison 2): The system was operated according to the process parameters set in Comparison 2, with the front end pressurized and dissolved gas, but depressurized to atmospheric pressure before entering the reactor.

[0082] Experimental data: Table 1: Measured data of effective ultraviolet radiation in the reaction system under different process conditions Group numbering Corresponding process Fluid state characteristics inside the reactor System pressure (MPa) <![CDATA[Measured average irradiance Iactual (mW / cm 2 ).]]> Relative light intensity transmittance η (%) benchmark group Pure water control Static, bubble-free, transparent 0.10 7.14 100.0 Test Group A Example 1 Dynamic, no visible bubbles, homogeneous 0.30 6.83 95.7 Test Group B Comparative Example 1 Dynamic, containing a large number of rising large bubbles 0.10 2.94 41.2 Test group C Comparative Example 2 Dynamic, milky-white microbubble suspension 0.10 2.18 30.5 .

[0083] Results Analysis and Conclusions: According to Table 1 and Appendix Figure 1 Based on the measured data, the following technical conclusions can be drawn: In Example 1 (Test Group A), after maintaining a system pressure of 0.30 MPa and undergoing isobaric gas-liquid separation at the front end, the effective ultraviolet irradiance inside the reactor reached 6.83 mW / cm². 2The relative light intensity transmission rate is as high as 95.7%. This value is very close to the pure water reference value. The slight light intensity loss (about 4.3%) is mainly attributed to the intrinsic absorption of ultraviolet light by dissolved ozone and hydrogen peroxide molecules in the water (which is also a necessary process for the generation of free radicals), rather than physical scattering loss. This confirms that the present invention has successfully constructed an optically transparent homogeneous reactive fluid through physical field modulation, in which ultraviolet photons can efficiently penetrate the water layer and act on the oxidant.

[0084] In contrast, Comparative Example 1 (Test Group B) used atmospheric pressure aeration mode, and the measured irradiance dropped sharply to 2.94 mW / cm². 2 The transmission rate was only 41.2%. This indicates that the macroscopic bubbles directly present in the reactor produced a severe physical shielding effect. The refraction and reflection at the gas-liquid interface resulted in nearly 60% of the ultraviolet light energy failing to penetrate the water body effectively, resulting in extremely low light energy utilization efficiency.

[0085] Even more significant is Comparative Example 2 (Test Group C), which simulated the condition of first pressurizing and dissolving gas followed by depressurization. This group exhibited the lowest measured irradiance, at only 2.18 mW / cm². 2 The transmittance dropped to 30.5%. This is a typical Mie scattering phenomenon. According to Henry's Law, ozone dissolved under high pressure will rapidly precipitate in large quantities in the form of micron-sized microbubbles when the pressure is suddenly reduced, giving the water a milky white suspended state. This causes severe non-absorbent attenuation of ultraviolet radiation when penetrating the liquid layer, resulting in the reaction system exhibiting the physical characteristics of high optical impedance and low transmittance.

[0086] In summary, the process strategy of combining S3 isobaric gas phase separation with S5 pressure-holding reaction adopted in this invention effectively eliminates the interference of bubbles (whether macroscopic or microbubbles) on the photochemical reaction, ensuring that the reaction system is always in a single-phase flow state with high light transmittance. This is the physical basis for achieving efficient synergistic catalysis.

[0087] Test Example 2: Quantitative Analysis of the Yield of Hydroxyl Radicals (·OH) in the System Experimental steps: (1) Prepare an alkaline stock solution of terephthalic acid (TPA) with a concentration of 2.0 mmol / L, using dilute sodium hydroxide solution as the solvent. TPA itself is non-fluorescent, but it can specifically capture hydroxyl radicals (·OH) in the solution to generate a unique product with strong fluorescence, 2-hydroxyterephthalic acid (2-HTPA). The amount of this product generated is strictly proportional to the amount of ·OH accumulated.

[0088] (2) Start the experimental setups corresponding to Example 1 (UV / H2O2 / O3 pressure holding system), Comparative Example 3 (UV / O3 pressure holding system, without H2O2), and Comparative Example 4 (UV / H2O2 pressure holding system, without O3) respectively. Continuously inject TPA stock solution at the reactor inlet using a precision metering pump to maintain the initial concentration of TPA in the reaction system at 0.5 mmol / L, ensuring an excess of probe molecules to capture all generated free radicals.

[0089] (3) After the reaction system has stabilized, water samples were collected from the reactor sampling port at reaction times of 0, 2, 5, 10, 20 and 30 minutes. After the water samples were rapidly filtered through a 0.22 μm filter membrane, excess sodium sulfite solution was immediately added to quench the residual oxidant and terminate the reaction.

[0090] (4) The fluorescence intensity of the water samples at each time point was measured using a fluorescence spectrophotometer (excitation wavelength 315 nm, emission wavelength 425 nm). The fluorescence intensity was determined based on a pre-established 2-HTPA standard concentration curve (concentration range 0–20 μmol / L, R0). 2 >0.999), converting the measured fluorescence signal into the cumulative concentration of hydroxyl radicals (μmol / L).

[0091] Experimental data: Table 2: Cumulative concentration of hydroxyl radicals (·OH) generated in different reaction systems over time Sampling time (min) <![CDATA[Example 1 (UV / H2O2 / O3) Concentration of ·OH (μmol / L)]]> <![CDATA[Comparative Example 3 (UV / O3) ·OH Concentration (μmol / L)]]> <![CDATA[Comparative Example 4 (UV / H2O2) ·OH Concentration (μmol / L)]]> 0 0.00 0.00 0.00 2 1.84 0.42 0.15 5 5.12 1.18 0.38 10 9.87 2.56 0.82 20 17.35 4.93 1.64 30 24.62 6.88 2.31 .

[0092] Results Analysis and Conclusions: According to Table 2 and Appendix Figure 2 Based on the detection data, the oxidation capacity and synergistic mechanism of each system are analyzed as follows: In Comparative Example 4 (UV / H2O2), the cumulative concentration of hydroxyl radicals generated at the end of the 30-minute reaction was only 2.31 μmol / L. This is because hydrogen peroxide has a low molar absorptivity (approximately 18–19 MΩ) at 254 nm. -1 cm -1 The quantum efficiency of direct photolysis to generate free radicals is limited, and the lack of ozone as an initiator for chain reactions results in the weakest oxidation capacity of a single UV / H2O2 system.

[0093] Comparative Example 3 (UV / O3) showed increased free radical production, with a cumulative concentration of 6.88 μmol / L after 30 minutes. Ozone, although possessing a high molar absorptivity (approximately 3300 MΩ), also exhibited improved free radical production. -1 cm -1 However, in the absence of a conjugate base (HO2) provided by hydrogen peroxide, -When ozone is used as an initiator, the photolysis of ozone mainly depends on hydroxide ions in water. The chain reaction transfer efficiency is low, and some ozone is directly consumed before photolysis, failing to be converted into free radicals with stronger oxidizing power.

[0094] Example 1 (UV / H2O2 / O3) exhibited significant synergistic effects, with a cumulative hydroxyl radical concentration of 24.62 μmol / L at 30 minutes. This value is not only much higher than any single system but also greater than the sum of Comparative Examples 3 and 4 (24.62 > 6.88 + 2.31), confirming the occurrence of a nonlinear synergistic reaction within the system. Mechanistically, this invention maintains a high concentration of dissolved ozone in the liquid phase through pressure holding, while the added hydrogen peroxide dissociates into perhydroxyl ions (HO2) in the water. - ), HO2 - As a highly efficient initiator, it reacts with dissolved ozone (Peroxone effect), greatly accelerating the chain decomposition of ozone. Simultaneously, combined with the high light flux environment confirmed in Test Example 1, both high concentrations of ozone and hydrogen peroxide molecules can fully absorb light energy, opening up dual free radical generation pathways through photolysis and chemical induction, thereby rapidly generating high concentrations of hydroxyl radicals per unit time.

[0095] Test Example 3: Evaluation of the depth removal effect of odor substances (2-MIB and GSM) Experimental steps: (1) Sample collection and pretreatment: When each group of reaction devices reaches the end of the set time point, immediately collect 40 mL of water sample from the outlet. Add excess sodium thiosulfate to the water sample to quench residual oxidant and prevent further reaction after sampling. Then add 10 g of sodium chloride to increase ionic strength (salting-out effect), and add 2-isobutyl-3-methoxypyrazine (IBMP) as an internal standard, and precisely adjust the internal standard concentration to 10 ng / L.

[0096] (2) Solid-phase microextraction (SPME): The treated water sample was placed in a 60°C constant temperature water bath with a magnetic stirrer, and the solid-phase microextraction handle equipped with a DVB / CAR / PDMS extraction fiber head was inserted. The headspace extraction mode was maintained, and the adsorption time was 30 minutes. The trace odor substances volatilized from the water sample were enriched by utilizing the phase equilibrium principle.

[0097] (3) Chromatography-mass spectrometry analysis: The adsorbed fiber head was inserted into the GC-MS injection port and desorbed at 250℃ for 3 minutes. Separation was performed using a DB-5MS capillary column. The temperature program was set as follows: initial temperature 40℃, held for 2 minutes, increased to 150℃ at 6℃ / min, and then increased to 240℃ at 10℃ / min. Selected ion scanning (SIM) mode was used for the mass spectrometer detector to lock onto characteristic ions of 2-MIB (m / z 95, 107, 135) and GSM (m / z 112, 125, 126) for quantitative analysis.

[0098] (4) Data calculation: The residual concentrations (ng / L) of 2-MIB and GSM in each water sample were calculated using the internal standard method, and the final removal rate was calculated in combination with the initial concentration (100±5ng / L).

[0099] Experimental data: Table 3: Detection data on odor removal efficiency under different process conditions Group Brief description of process characteristics 2-MIB residual concentration (ng / L) 2-MIB Removal Rate (%) GSM residual concentration (ng / L) GSM removal rate (%) Example 1 Standard parameters (0.3MPa / ternary synergy) 1.6 98.4 2.1 97.9 Example 2 Low energy consumption / low concentration mode 7.8 92.2 8.5 91.5 Example 3 High organic background / high intensity mode 4.3 95.7 5.2 94.8 Example 4 Pressure adjustment mode (0.25MPa) 2.9 97.1 3.4 96.6 Comparative Example 1 Atmospheric pressure aeration (bubble interference) 52.4 47.6 58.7 41.3 Comparative Example 2 Dissolve the gas first, then depressurize (microbubble interference) 63.8 36.2 69.1 30.9 Comparative Example 3 <![CDATA[No H2O2 (UV / O3 binary)]]> 28.5 71.5 34.2 65.8 Comparative Example 4 <![CDATA[No O3 (UV / H2O2 binary)]]> 76.2 23.8 81.4 18.6 .

[0100] Results Analysis and Conclusions: According to Table 3 and Appendix Figure 3 Based on the test data, the analysis conclusions regarding the effects of each process are as follows: Examples 1-4 demonstrate the deep mineralization capability of trace odor substances, with removal rates consistently above 90%, and approaching 99% in some conditions. In Example 1, under standard parameters, the residual concentrations of 2-MIB and GSM decreased to 1.6 ng / L and 2.1 ng / L, respectively, far below the human ear's olfactory threshold for these two substances (typically 10 ng / L), proving that the process can effectively remove sensory odors in practical applications. Even in Example 3, with a high organic background, despite the competitive consumption of hydroxyl radicals by humic acid, a removal rate of over 95% was maintained by increasing system pressure and light intensity, confirming the system's robustness in handling complex water conditions.

[0101] In contrast, the comparative groups showed a significant decline in performance. The removal rates of both Comparative Examples 1 and 2 were generally below 50%, with Comparative Example 2 (under reduced pressure microbubble conditions) performing the worst, achieving a 2-MIB removal rate of only 36.2%. This is highly consistent with the photophysical test results of Test Example 1: the diffuse bubble clusters (especially microbubbles) within the reactor severely blocked the transmission of ultraviolet light in the liquid phase, preventing photons from effectively activating the oxidant. Even with sufficient ozone and hydrogen peroxide, the lack of light-driven energy meant the system could not generate enough free radicals to degrade chemically stable odor substances. In this case, the primary removal mechanism degenerated into simple direct ozone oxidation, resulting in low efficiency.

[0102] Data from Comparative Example 3 (without H2O2) and Comparative Example 4 (without O3) validated the chemical necessity of the ternary synergistic effect. Relying solely on the UV / H2O2 system (Comparative Example 4), the removal rate was less than 25%, indicating that the free radicals generated by the photolysis of hydrogen peroxide alone are insufficient to address the degradation of low-concentration, diffusion-controlled trace pollutants. While the UV / O3 system (Comparative Example 3) achieved a removal rate of approximately 70%, it was still significantly lower than the 98.4% of Example 1. This demonstrates that only in the "UV / H2O2 / O3" ternary system, utilizing the photo-chemical coupling chain reaction between high-concentration dissolved ozone and hydrogen peroxide under pressure, can the explosive generation of hydroxyl radicals be achieved, thereby overcoming the kinetic bottleneck of odor substance degradation.

[0103] Test Example 4: Reaction Kinetic Constant ( Comparative analysis of values Experimental steps: (1) 2-Methylisoborneol (2-MIB) was selected as the target pollutant. Simulated raw water with an initial concentration of 100±5 ng / L was prepared, the water temperature was controlled at 20±1℃, and the pH value was adjusted to 7.5.

[0104] (2) Start the processing devices of Example 1 (pressure-holding homogeneous flow), Comparative Example 1 (atmospheric pressure aeration flow), and Comparative Example 2 (dissolved gas followed by depressurized flow) respectively. The power density of the light source in each group of devices is kept consistent to ensure that the ultraviolet light input energy is the same.

[0105] (3) After the system has stabilized, during the reaction time Water samples were collected from the sampling ports of each reactor at 0, 5, 10, 15, 20, and 30 minutes. Immediately after sample collection, excess sodium thiosulfate solution was added to quench residual ozone and hydrogen peroxide, followed by salting out with sodium chloride.

[0106] (4) The residual concentration of 2-MIB in the water samples at each time point was determined by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC / MS). .

[0107] (5) Based on the pseudo-first-order reaction kinetic model With reaction time The x-axis is... A linear regression is performed on the ordinate. The apparent reaction rate constant is obtained by calculating the slope of the straight line. ( ), and calculate the linear correlation coefficient. To verify the model's fit.

[0108] Experimental data: Table 4: Recording of 2-MIB degradation kinetics data under different process conditions Sampling time (min) Example 1 (Ct, ng / L) Comparative Example 1 (Ct, ng / L) Comparative Example 2 (Ct, ng / L) 0 102.4 101.8 103.1 5 48.2 91.5 92.8 10 23.5 82.3 86.4 15 11.1 74.1 80.2 20 5.4 67.8 74.5 30 1.6 52.4 63.8 kinetic parameters numerical values numerical values numerical values <![CDATA[Rate constant k (min −1 ).]]> 0.1386 0.0221 0.0158 <![CDATA[Fitting correlation coefficient R 2 > 0.9982 0.9915 0.9876 .

[0109] Results Analysis and Conclusions: According to Table 4 and Appendix Figure 4 Based on the kinetic fitting data, the reaction rates and engineering significance of each process are analyzed as follows: Apparent reaction rate constant of Example 1 Up to 0.1386min -1 It exhibits extremely rapid degradation characteristics. In contrast, Comparative Example 1 (atmospheric pressure aeration) showed... The value is only 0.0221 min. -1 Comparative Example 2 (Depressurized Microbubbles) The lowest value was 0.0158 min. -1 Calculations show that the reaction rate of Example 1 is 6.27 times that of Comparative Example 1 and 8.77 times that of Comparative Example 2.

[0110] This significant kinetic advantage directly confirms the effectiveness of the "physical field regulation" mechanism of this invention. In Example 1, by maintaining pressure to eliminate bubble interference, the photon efficiency within the reaction system is maximized. Combined with the high concentration of dissolved ozone brought about by high-pressure dissolved gas, the concentration of hydroxyl radicals generated per unit time is maintained at an extremely high level, thereby driving the rapid mineralization of odor substances.

[0111] Conversely, the data in Comparative Example 2 (0.0158 min) -1 This further confirms that the inhibitory effect of Mie scattering induced by microbubbles on photochemical reactions even exceeds that of traditional large-bubble aeration (0.0221 min). -1 Although Comparative Example 2 underwent pressurized gas dissolution at the front end, incorrect decompression operation led to the precipitation of a large number of microbubbles, creating a high photoresistivity environment and severely slowing down the reaction process.

[0112] From an engineering application perspective, a higher reaction rate constant... This indicates a significant reduction in the hydraulic retention time (HRT) required to achieve the same removal rate. For example, to remove 90% of the pollutants, Example 1 requires only about 16 minutes, while Comparative Example 1 requires over 100 minutes. This demonstrates that the process of this invention can significantly reduce the design volume and footprint of the photocatalytic reactor, effectively lowering construction costs and operating energy consumption.

[0113] Test Example 5: Carcinogenic byproduct bromate (BrO3) - Generate risk assessment Experimental steps: (1) Preparation of experimental water samples: The simulated raw water B rich in bromide ions prepared in Preparation Example 2 (bromine ion background concentration 200±10μg / L) was selected as the test object.

[0114] (2) Three sets of comparative operating conditions were set: Example 5 adopted the hydrogen peroxide-rich process optimized by the present invention (H2O2 / O3 mass ratio set to 4.5:1); Comparative Example 3 was a single ozone oxidation process (no H2O2 added); Comparative Example 5 was a low hydrogen peroxide process (H2O2 / O3 mass ratio of 0.75:1, corresponding to H2O2 dosage of 1.5 mg / L). Each set of devices was operated under the same system pressure (0.30 MPa) and hydraulic residence time.

[0115] (3) After the reaction is completed, the water sample is collected immediately, filtered through a 0.45 μm microporous membrane, and ethylenediamine (EDA) solution is added to the filtrate to instantly quench the residual ozone and free radicals and prevent bromate from being generated after sampling.

[0116] (4) The water sample was analyzed using an ion chromatograph (equipped with a conductivity detector and an anion separation column). The eluent was a sodium carbonate / sodium bicarbonate system, with a flow rate of 1.0 mL / min. Qualitative analysis was performed based on retention time, and quantitative analysis was performed using the external standard method with a standard curve to calculate the bromate (BrO3) content in the water. - The concentration of ).

[0117] Experimental data: Table 5: Effluent bromate (BrO3) under different process conditions - Generate concentration detection data Group Process conditions description Initial bromide ion concentration (μg / L) Bromate formation concentration (μg / L) Does it exceed the limit (10 μg / L)? Example 5 <![CDATA[Working condition with high H2O2 content (mass ratio 4.5:1)]]> 204.5 3.8 Meets safety standards Comparative Example 3 <![CDATA[Without H2O2 (pure O3 working condition)]]> 198.2 42.7 Seriously exceeding the standard Comparative Example 5 <![CDATA[Low H2O2 operating condition (mass ratio 0.75:1)]]> 201.3 16.3 Exceeding the standard .

[0118] Results Analysis and Conclusions: According to Table 5 and Appendix Figure 5 Based on the ion chromatography detection results, the control mechanism of byproducts in the high-pressure reaction system is analyzed as follows: In Comparative Example 3 (pure O3), bromate concentrations as high as 42.7 μg / L were detected in the effluent, exceeding the national standard limit by four times. This is because the pressure-holding process employed in this invention, while significantly increasing the liquid-phase ozone concentration (enhancing oxidation capacity), also significantly strengthens the reaction between ozone and bromide ions (Br₂) in the water. - The probability of exposure to Br. In the absence of inhibitors, high concentrations of dissolved ozone rapidly increase the risk of Br. - Oxidation to hypobromic acid / hypobromate (HBrO / BrO) - ), and further oxidize it into the stable carcinogen bromate (BrO3). - This indicates that while simply pursuing high-pressure dissolved ozone can degrade pollutants, it poses significant chemical safety risks in high-bromine water.

[0119] Although a certain amount of hydrogen peroxide was added to Comparative Example 5 (low H2O2), the bromate concentration still reached 16.3 μg / L, failing to meet the safety standard. This indicates that at the low mass ratio of 0.75:1, hydrogen peroxide mainly participated in the conjugated reaction with ozone to generate hydroxyl radicals, while the remaining amount used for reduction blocking was insufficient to completely inhibit the further oxidation of intermediate hypobromate.

[0120] Example 5 (rich in H2O2) achieved significant control, with the effluent bromate concentration at only 3.8 μg / L, far below the safety threshold of 10 μg / L. The mechanism lies in the fact that the "ternary synergistic" system constructed in this invention utilizes the dual role of hydrogen peroxide in microdynamics: on the one hand, it acts as a co-catalyst to generate free radicals; on the other hand, it utilizes its reducing properties to rapidly reduce the intermediate hypobromic acid (HBrO) back to bromide ions (Br₂O₃). - This "oxidation-reduction" cycle mechanism effectively breaks the cycle from Br. - To BrO3 - Chemical pathways of transformation. Experiments have shown that even in a 0.30 MPa high-pressure ozone-rich environment designed to enhance oxidation, maintaining a mass ratio of 4.5:1 is sufficient to achieve deep mineralization of organic pollutants while effectively controlling the risk of carcinogenic byproduct formation through a chemical competition mechanism, thus ensuring the safety of the process water supply.

[0121] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for degrading an odor substance in water by ultraviolet hydrogen peroxide synergistic catalytic ozone, characterized in that, Includes the following steps: S1. Raw water pretreatment: Filter raw water containing odorous substances to reduce water turbidity and thus reduce the scattering of light by suspended particles. S2, Ozone pressurized dissolved air: The pretreated water is pumped into the dissolved air system, and ozone is introduced under a set pressure P1, so that the ozone exists in the water in a dissolved state. S3, Isobaric gas phase separation: Under the condition of maintaining the system pressure P1 without decreasing, the gas-liquid mixture is separated to remove undissolved free gas bubbles and obtain a homogeneous transparent fluid that is saturated or supersaturated with ozone. S4. Establishing a reaction system: Inject hydrogen peroxide solution into the homogeneous transparent fluid, using hydrogen peroxide as a co-catalyst and chain reaction initiator; S5, Pressure-maintaining synergistic reaction: The mixed fluid is introduced into the photocatalytic reactor, and the pressure inside the reactor is maintained at P1. Under ultraviolet light irradiation, dissolved ozone and hydrogen peroxide are used to synergistically generate hydroxyl radicals to mineralize and degrade odor substances.

2. The method according to claim 1, wherein the method is characterized by, The set pressure P1 is in the range of 0.20MPa to 0.40MPa; the concentration of dissolved ozone is controlled at 1.0mg / L to 5.0mg / L; the ozone mass transfer driving force is improved and microbubble precipitation is suppressed by pressure regulation.

3. The method according to claim 1, wherein the method is characterized by, In step S3, the residence time for the isobaric gas phase separation is 1.5 to 3.0 minutes; after separation, the relative ultraviolet light transmittance of the fluid in the reactor of step S5 is maintained above 95%.

4. The method according to claim 1, wherein the method is characterized by, In step S4, the concentration of hydrogen peroxide added to the water sample is 7.0 mg / L to 20.0 mg / L, and the mass ratio of hydrogen peroxide to dissolved ozone is controlled to be 2:1 to 7:

1.

5. The method according to claim 4, wherein the method is characterized by, For raw water with a background bromide ion concentration higher than 100 μg / L, in step S4, the mass ratio of hydrogen peroxide to dissolved ozone is controlled to be no less than 4.5:

1. The hydrogen peroxide is used to construct a reducing barrier to reduce the intermediate product hypobromic acid to bromide ions, thereby inhibiting the formation of the carcinogenic byproduct bromate.

6. The method according to claim 4, wherein the method is characterized by, For raw water with a total organic carbon (TOC) content higher than 3.0 mg / L, the set pressure P1 is adjusted to 0.35 MPa to 0.45 MPa in step S2, and the amount of hydrogen peroxide added is increased simultaneously in step S4 to maintain the mass ratio of hydrogen peroxide to dissolved ozone at 4:1 to 5:

1.

7. The method for the degradation of odor substances in water by ultraviolet hydrogen peroxide and co-catalyzed ozone according to claim 1, characterized in that, In the step S5, the intensity of the ultraviolet light is 6.5 mW / cm 2 ~ 7.5 mW / cm 2 and the hydraulic retention time is 20 ~ 40 minutes; the main wavelength of the ultraviolet light is 253.7 nm.

8. The method for the degradation of odor substances in water by ultraviolet hydrogen peroxide synergistically catalyzing ozone, as described in claim 1, is characterized in that, In step S4, the specific method for establishing the reaction system is as follows: a pipe mixer is set in the inlet pipe of the photocatalytic reactor, and hydrogen peroxide solution is injected online under pressure. The mixing time is controlled within 5 seconds, and then the system enters the ultraviolet radiation region of step S5.

9. The method for the degradation of odor substances in water by ultraviolet hydrogen peroxide synergistically catalyzing ozone, as described in claim 1, is characterized in that, In step S1, the filtration process includes passing the water through a sand filter column and a precision filter in sequence to control the turbidity of the effluent to be less than 0.5 NTU, preferably less than 0.2 NTU.

10. The method for the degradation of odor substances in water by ultraviolet hydrogen peroxide synergistically catalyzing ozone, as described in claim 1, is characterized in that, The method further includes a post-treatment step S6: the reaction effluent from step S5 is depressurized by a back pressure valve and then passes through a granular activated carbon adsorption column. The empty bed contact time is 10-15 minutes to quench residual hydrogen peroxide and adsorb trace amounts of oxidation byproducts.

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