Ozone catalytic oxidation sewage treatment equipment and treatment method

Abstract

This invention discloses an ozone catalytic oxidation wastewater treatment device and method. The device includes at least a tubular ozone reactor, comprising a reaction tube, an ozone generator, and a reagent tank. A catalyst module loaded with metal hydroxyl oxides is installed inside the reaction tube. The ozone generator is connected to the reaction tube via a pipe; the reagent tank is also connected to the reaction tube via a pipe. Several reaction tubes are connected in series to form a multi-stage reaction tube system. The two ends of each multi-stage reaction tube are used for wastewater inlet and outlet, respectively. The multi-stage reaction tube system is divided into n levels, each level including at least two reaction tubes. Along the wastewater flow direction, the last reaction tube in the same level simultaneously inputs ozone and reagents, or only inputs ozone, while the other reaction tubes are disconnected from inputting ozone and reagents, or only inputting reagents. The method involves applying the above-mentioned device to treat wastewater. This invention improves oxidizing power and reaction efficiency through multi-stage enhanced ozone catalytic oxidation, achieving stable equipment operation and meeting process standards and production targets.

Description

Technical Field

[0001] This disclosure belongs to the field of wastewater treatment technology, specifically relating to an ozone catalytic oxidation wastewater treatment device and treatment method. Background Technology

[0002] In the field of sewage and wastewater treatment, the mainstream advanced treatment technology is Fenton oxidation technology. Under acidic conditions, ferrous salts are used as catalysts, and hydrogen peroxide is used to generate hydroxyl radicals through a catalytic reaction. The hydroxyl radicals act as oxidants to pollutants in the water, oxidizing the pollutants into stable and harmless substances, thereby achieving the purpose of water purification.

[0003] The aforementioned ferrous salts participate in the Fenton oxidation reaction as catalysts. Because ferrous salts are readily soluble in water, they are difficult to separate from the water body. Furthermore, after the Fenton reaction, ferrous salts are converted to ferric salts, losing their catalytic effect. Therefore, in actual production, although ferrous salts act as catalysts, they are not recovered as catalysts but are consumed as consumables, resulting in a large amount of iron-containing sludge (referred to as iron sludge). Under typical Fenton process operation, the ratio of iron sludge production to the removed chemical oxygen demand (COD) is approximately 3–6, meaning that for every 1g of COD removed, 3–6g of iron sludge is produced. The amount of iron sludge produced is enormous, and if not properly treated, it will cause secondary pollution. In addition, Fenton oxidation technology also suffers from significant problems such as complex control and high risks associated with reagent management. Therefore, ozone catalytic oxidation technology has emerged, attracting considerable attention due to its advantages such as simple control, stable operation, and no secondary pollution.

[0004] Ozone catalytic oxidation technology is an advanced oxidation technology. On one hand, it utilizes the oxidizing properties of ozone itself to oxidize pollutants; on the other hand, ozone reacts with water under the action of a catalyst to generate hydroxyl radicals, which then oxidize pollutants. The former, ozone, has a relatively low oxidation potential of 2.07V, while the latter, hydroxyl radicals, has an oxidation potential of 2.80V. A higher oxidation potential means more pollutants can be oxidized. Therefore, in the ozone catalytic oxidation reaction system, we aim to involve as many hydroxyl radicals as possible in the reaction, rather than relying solely on ozone.

[0005] Regarding ozone catalytic oxidation technology, the most frequently mentioned aspect in current literature and applications is the ozone catalytic oxidation reactor. Ozone and other reagents are mostly added via jet or pipe mixing, which causes premature reaction and natural decomposition of ozone, thus reducing the generation of hydroxyl radicals. Furthermore, low concentrations of ozone preferentially select iron oxide-based catalysts rather than oxidizing pollutants, accelerating catalyst consumption and increasing the iron concentration in the effluent. If more stable catalysts such as aluminum-based catalysts are used, low concentrations of ozone may not be able to break down the passivation layer or activate the catalyst, failing to improve ozone treatment efficiency and, in the long run, accelerating catalyst scaling and clogging.

[0006] As is well known, ozone is gaseous at room temperature and pressure, while the pollutants to be treated exist in liquid wastewater. For the two to react, they need to overcome the barrier between different phases. On the one hand, the contact area between the different phases is small. Many documents and patents point out that reducing the volume of ozone bubbles to form microbubbles can increase the contact area between the different phases and improve the reaction efficiency. Even so, the contact area between the different phases in this method is still much smaller than the contact area between molecules at the same phase. On the other hand, in the same phase, molecules only need to come into contact to react with each other, while in the different phase, the movement of pollutants and ozone molecules needs to reach or cross the contact surface between the different phases before they can react with each other. Therefore, the mass transfer and reaction efficiency of the different phase contact are both low.

[0007] To achieve the aforementioned in-phase contact reaction, dissolving ozone in water is relatively easy. However, ozone has low solubility in water, generally only 3-7 mg / L. Furthermore, the gas produced by ozone generators is mostly oxygen (oxygen-enriched or pure oxygen source) or nitrogen (air source). Oxygen and ozone compete for dissolution in water, reducing the amount of ozone that can be dissolved, making it difficult to achieve the in-phase contact reaction.

[0008] The above analysis of the shortcomings of ozone catalytic oxidation technology reveals, from a macroscopic perspective, its weak oxidizing power, low reaction efficiency, poor pollutant removal effect, and high investment and maintenance costs. These problems directly hinder the promotion and application of ozone catalytic oxidation technology, preventing it from becoming a candidate for Fenton oxidation technology and thus preventing it from replacing Fenton oxidation technology as the mainstream technology. Therefore, in order to overcome these problems, it is crucial to develop a new type of ozone catalytic oxidation treatment equipment and process. Summary of the Invention

[0009] The main objective of this disclosure is to provide an ozone catalytic oxidation wastewater treatment device and method, which can significantly improve oxidizing power and reaction efficiency, reduce investment and operation and maintenance costs, and achieve stable equipment operation and process compliance with production standards. To achieve the above objectives, this disclosure adopts the following technical solution:

[0010] Based on a first aspect of this disclosure, this disclosure provides an ozone catalytic oxidation wastewater treatment device.

[0011] The ozone catalytic oxidation wastewater treatment equipment includes a tubular ozone reactor, comprising a reaction tube, an ozone generator, and a reagent tank. A catalyst module loaded with metal hydroxyl oxides is installed inside the reaction tube. The ozone generator is connected to the reaction tube via a pipe for inputting ozone. The reagent tank is connected to the reaction tube via a pipe for inputting reagents participating in the ozone catalytic oxidation reaction. Several reaction tubes are connected in series, and the delivery positions of ozone and reagents are controlled, forming a multi-stage reaction tube system. The two ends of this multi-stage reaction tube are respectively used to connect to wastewater and discharge treated wastewater. The multi-stage reaction tube system is divided into n levels, where n≥1. Each level includes at least two reaction tubes. Along the wastewater flow direction, the last reaction tube in the same level simultaneously inputs ozone and reagents or only inputs ozone, while the other reaction tubes are disconnected from inputting ozone and reagents or only inputting reagents.

[0012] In at least one embodiment, each of the reaction tubes is connected to the ozone generator and the reagent tank. The multi-stage reaction tube includes two reaction tubes. An ozone valve is provided in the pipeline between the reaction tube and the ozone generator, and a reagent valve is provided in the pipeline between the reaction tube and the reagent tank. Inlet valves and outlet valves are connected to the pipelines at both ends of the multi-stage reaction tube. The inlet valves and outlet valves are used in conjunction to reverse the direction of the sewage flow at regular intervals. The ozone valves and reagent valves are used in conjunction to alternately and simultaneously input and disconnect ozone and reagent into the same reaction tube, or to alternately input ozone and reagent, depending on the change in the direction of the sewage flow.

[0013] In at least one embodiment, the catalyst module is a perforated plate loaded with metal hydroxyl oxides; the perforated plate is wound several times in a spiral direction, and finally forms a column that can be filled into the reaction tube.

[0014] In at least one embodiment, the method for preparing the catalyst module includes:

[0015] A perforated iron or steel plate is used as the perforated plate, and a perforated column is obtained by winding it several times in a spiral direction.

[0016] Clean the mesh column by first soaking it in a 0.5-2 wt% zinc chloride solution for 1-2 hours, then removing it and placing it in a vacuum or a closed high-temperature furnace filled with inert gas, and calcining it at 150-200°C for 0.5-1 hours.

[0017] The mesh column is removed from the high-temperature furnace and placed in 10-30 wt% hydrogen peroxide solution with a pH of 3-6 when its surface temperature drops to 50-100°C. After the violent reaction subsides, the column is removed and dried to obtain the catalyst module.

[0018] In at least one embodiment, the perforated plate is made of conventional iron mesh or steel mesh;

[0019] Alternatively, the perforated plate can be manufactured by a method comprising:

[0020] Cutting slits are made on the surface of an iron plate or steel plate. The cutting slits include a first cutting slit and a second cutting slit, which are respectively opened along the length direction and the width direction of the iron plate or steel plate.

[0021] The iron or steel plate is stamped, and the surface of the stamping die is provided with several rows of concave and convex structures. The concave and convex structures include continuously alternating protrusions and depressions, and the protrusions and depressions are distributed in correspondence with the grid formed by the cutting seam. The stamped iron or steel plate also forms a concave and convex structure, and holes are formed between adjacent protrusions and depressions in its concave and convex structure.

[0022] In at least one embodiment, the cleaning method includes:

[0023] First, place the mesh column in a 45-90 wt% ethanol solution, soak for 2-6 hours, then remove it and rinse off the residual ethanol.

[0024] The mesh column is then placed in a 5-10 wt% sodium hydroxide solution and soaked for 2-6 hours before being removed and rinsed to remove any residual sodium hydroxide.

[0025] In at least one embodiment, the treatment apparatus further includes anoxic-aerobic bioreactor and a tower-type ozone reactor;

[0026] The anoxic-aerobic bioreactor includes an anoxic tank and an aerobic tank; wastewater is introduced into the upper part of the anoxic tank and is connected to the aerobic tank at the lower part; a membrane module is provided in the middle and / or upper part of the aerobic tank, and the wastewater treated by the membrane module is transported to the tubular ozone reactor through a pipeline.

[0027] The tower-type ozone reactor includes a reaction tower, which contains a catalyst packing and a dissolved gas release device. The dissolved gas release device is located below the catalyst packing and is connected to the wastewater treated by the tubular ozone reactor through a pipeline. The reaction tower above the catalyst packing is provided with an outlet for discharging the treated wastewater.

[0028] In at least one embodiment, the top of the reaction tower is provided with an outlet and an inlet; the outlet pipe is connected to the aerobic tank.

[0029] In at least one embodiment, the pipe between the reaction tube and the ozone generator or reagent tank extends into the reaction tube.

[0030] In at least one embodiment, the tubular ozone reactor further includes a water inlet tank, the pipe of which is connected to the multi-stage reaction tube, and a booster pump is provided in the pipeline between the two.

[0031] Based on a second aspect of this disclosure, this disclosure also provides a method for treating wastewater by ozone catalytic oxidation.

[0032] This wastewater treatment method utilizes the aforementioned ozone catalytic oxidation wastewater treatment equipment during the wastewater treatment process.

[0033] In at least one embodiment, the wastewater to be treated first reaches the anoxic-aerobic bioreactor. The first step is to treat it through anaerobic and anoxic microbial metabolism in the anoxic tank, the second step is to treat it through aerobic microbial metabolism in the aerobic tank, and the third step is to perform solid-liquid separation through a membrane module. Then the wastewater enters the tubular ozone reactor, where it undergoes alternating reduction deoxygenation and catalytic oxidation reactions in a multi-stage reaction tube. Finally, it enters the tower ozone reactor, where water purification is completed by the combined action of ozone from microbubbles and a catalyst.

[0034] Compared with the prior art, this disclosure can achieve the following beneficial effects:

[0035] (1) This disclosure employs a multi-stage reaction method, involving multiple dosings of ozone into the water and multiple reactions, resulting in a more complete reaction and significantly increasing the utilization rate of reagents and ozone. The ozone dosage is low, with an O3 / COD mass ratio of only 0.5–1.5 (compared to 2–4 for traditional ozone catalytic oxidation treatment technology), saving on equipment investment and operating costs. The ozone provided for catalytic oxidation reacts completely, leaving no ozone residue in the exhaust gas, preventing ozone waste, eliminating secondary pollution, and being environmentally friendly.

[0036] (2) Since ozone that participates in the catalytic oxidation reaction will eventually be decomposed into oxygen and dissolved in water, this disclosure adopts a multi-stage and alternating operation mode of catalytic oxidation reaction and reduction reaction for sewage and wastewater. Under the premise of ensuring the normal progress of catalytic oxidation reaction, the dissolved oxygen in the water is removed in time by the reduction reaction, thereby improving the solubility of ozone in water in the subsequent catalytic oxidation reaction and improving the contact reaction efficiency.

[0037] (3) The present invention can divide the reaction tube into two groups, and the two groups take turns to carry out catalytic oxidation and reduction deoxygenation reactions. First, it can prevent the catalyst surface from becoming passivated, which would affect the reduction deoxygenation effect. Second, it can prevent or slow down the loss of catalytic components such as hydroxyl iron oxide loaded on the catalyst, which cannot be replenished in time, resulting in a reduction in the catalytic oxidation effect. Third, it can achieve the backwashing process of the catalyst by reversing the direction of water flow, thus preventing blockage.

[0038] (4) The equipment disclosed herein adopts a tubular reactor (reaction tube) with high flow rate, large throughput, and small volume. This not only increases the material mixing effect, reduces the processing load by reflux, and improves the reaction rate and depth, but also facilitates equipment disassembly, cleaning, adjustment, and catalyst replacement. The reaction tube volume is relatively small, and its supporting pressurized water pump is also correspondingly smaller. Compared with traditional wet oxidation technology, the equipment investment and operating costs are greatly reduced, and a high-pressure environment is easier to achieve.

[0039] (5) This disclosure also provides a method for manufacturing a novel catalyst packing (catalyst module), which uses iron and steel as the base material and is slowly consumed during operation, avoiding the problems of scaling and clogging that are common in commercially available spherical catalysts. The catalyst module is loaded with iron-based and zinc-based main catalytic active components and has the advantages of simple manufacturing, low cost, large specific surface area, high density, stable structure, large water flux, good catalytic effect, and is not easily damaged or deformed.

[0040] (6) This disclosure utilizes pressurization to dissolve gaseous ozone into the liquid phase, enabling ozone to fully react with water pollutants, catalysts, and reagents in the same phase, thus transforming heterogeneous contact into homogeneous contact and overcoming the barrier of heterogeneous interfaces to material contact. Furthermore, under high pressure, the medium density increases, and the molecular collision rate increases, greatly improving the efficiency and depth of the catalytic oxidation reaction; it also increases the reducibility of pollutants, lowers the "threshold" for chemical reactions, and has a good treatment effect on chemically stable and low-concentration pollutants, making it suitable for application in advanced treatment processes.

[0041] (7) The pipeline used for adding reagents and ozone in this disclosure extends deep into the reaction tube, and water is evenly distributed. After the reagents and ozone are added from the pipeline, the reagents, ozone, pollutants and catalyst react with each other simultaneously, which can participate in the catalytic oxidation reaction in the shortest time. This avoids the reagents and ozone from reacting with other substances in the water during transportation and mixing and being consumed prematurely, which is beneficial to improving the depth and efficiency of the catalytic oxidation reaction.

[0042] (8) The gas after participating in the catalytic oxidation reaction contains a high concentration of oxygen. It is transported to the front-end aerobic tank for aeration, which is more conducive to forming an aerobic environment with a high concentration of dissolved oxygen, which is beneficial to aerobic biochemical treatment. At the same time, because the oxygen content of the aerobic tank is high, the aeration volume is reduced and the blower air volume is reduced, which can save equipment investment and operating costs. Attached Figure Description

[0043] One or more embodiments of this disclosure will now be described by way of example only with reference to the accompanying drawings, in which:

[0044] Figure 1 A basic connection diagram of a tubular ozone catalytic oxidation wastewater treatment device provided for embodiments of this disclosure;

[0045] Figure 2 A detailed connection diagram of the tubular ozone catalytic oxidation wastewater treatment equipment provided for embodiments of this disclosure;

[0046] Figure 3 for Figure 1 A schematic diagram of the anoxic-aerobic bioreactor in the embodiment;

[0047] Figure 4 for Figure 1 A schematic diagram of the tubular ozone reactor in the embodiment;

[0048] Figure 5 for Figure 1 A schematic diagram of the tower-type ozone reactor in the embodiment;

[0049] Figure 6 A schematic diagram of the structure of the perforated plate (left) and catalyst module (right) provided for embodiments of this disclosure. Detailed Implementation

[0050] The present disclosure will now be described in detail with reference to exemplary embodiments shown in the accompanying drawings. However, it should be understood that the present disclosure may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein.

[0051] Catalyst packing / catalyst module

[0052] This disclosure provides a method for preparing a catalyst packing material. This catalyst packing material can be used in the tubular ozone reactor of this disclosure as a catalyst module within the reaction tube, and as a catalyst packing material in a tower-type ozone reactor.

[0053] The preparation method of the catalyst packing or catalyst module includes the following steps:

[0054] 1) A perforated iron or steel plate is used as the perforated plate and wound around several times in a spiral direction to obtain a perforated column.

[0055] Preferably, a rolling machine is used to bend and roll the perforated plate, thereby winding the perforated plate. The diameter of the rolling shaft of the rolling machine is preferably 20-30mm. The rolling process is carried out along the long side of the perforated plate. The diameter of the rolling is adjusted and increased for each turn, so that the perforated plate is rolled layer by layer without being flattened, until the entire perforated plate is rolled. Finally, the rolled perforated plate is fixed by welding or binding with corrosion-resistant materials such as 304 stainless steel wire to avoid stress deformation. At this time, the perforated plate is columnar, that is, a perforated column. The height of the perforated column is determined by the width of the iron plate or steel plate, and the selectable range is 0.5-2.0m.

[0056] 2) Clean the mesh columns by first immersing them in a 0.5–2 wt% zinc chloride solution for 1–2 hours, then removing them and placing them in a vacuum or a sealed high-temperature furnace filled with inert gas, and calcining them at 150–200°C for 0.5–1 hour. This step etches the surface of the mesh columns with zinc chloride, increasing the specific surface area, and simultaneously loading zinc elements to enhance the catalytic oxidation effect.

[0057] 3) Remove the mesh column from the high-temperature furnace. When its surface temperature drops to 50-100°C, immerse it in 10-30 wt% hydrogen peroxide solution with a pH of 3-6. After the vigorous reaction subsides, remove and dry it to obtain the catalyst module. Through this step, the iron and zinc elements contained in the mesh column are transformed into iron hydroxyl oxide and zinc hydroxyl oxide compounds, which have strong oxidizing properties and can directly participate in catalytic oxidation reactions. The final catalyst module is as follows: Figure 6 As shown on the right.

[0058] The cleaning process may specifically include the following steps:

[0059] I) First, place the mesh column in a 45-90 wt% ethanol solution and soak for 2-6 hours, then remove and rinse off the residual ethanol; II) Next, place the mesh column in a 5-10 wt% sodium hydroxide solution and soak for 2-6 hours, then remove and rinse off the residual sodium hydroxide. In this way, impurities such as oil can be removed from the surface of the mesh column, and the surface will have a reducing potential.

[0060] The perforated plate can be prepared by the following steps:

[0061] a) Cutting slits on the surface of an iron plate or steel plate, the cutting slits including a first cutting slit and a second cutting slit, the former two being opened along the length direction and the width direction of the iron plate or steel plate, respectively.

[0062] The preferred material is an iron or steel plate with a thickness of 0.5–2.0 mm, a width of 0.5–2.0 m, and a length of 3–10 m. The depth of a single cut is preferably 2–5 mm, and the width should be as small as possible. The first cut is arranged parallel to each other at equal intervals (1–3 mm) along the length direction, and the second cut is arranged parallel to each other at equal intervals (1–3 mm) along the width direction and intersects with the first cut, thus obtaining an iron or steel plate with regularly distributed cuts.

[0063] b) The iron or steel plate is stamped, and the surface of the stamping die has several rows of concave and convex structures, the concave and convex structures including alternating protrusions and depressions, and the protrusions and depressions are distributed correspondingly to the grid formed by the cutting seams; the stamped iron or steel plate also forms a concave and convex structure, and holes are formed between adjacent protrusions and depressions in its concave and convex structure. The final perforated plate is as follows: Figure 6 As shown on the left.

[0064] The stamping die is a specific die with a surface featuring a regularly distributed pattern of concave and convex structures. The arrangement of these structures corresponds to the cutting slit arrangement described in S1, and the depth of the concave and convex structures is preferably 0.5–3.0 mm. After stamping, a sheet of iron or steel with a regularly distributed concave and convex structure is obtained. Because of the prior cutting process, the concave and convex structures simultaneously generate holes during forming. The processed sheet of iron or steel has an overall mesh-like structure, with a thickness increased to 1.0–5.0 mm, exhibiting excellent structural strength and resisting collapse and deformation.

[0065] In this invention, commercially available iron mesh or steel mesh can be used as a substitute. However, the commercially available iron mesh or steel mesh used should, in comparison with the mesh plate obtained in steps a) and b) above, reach 50% of the mass of the mesh plate under the same area, and its structural strength should be equivalent to that of the mesh plate obtained by this method. This is to prevent problems such as excessive consumption of catalyst modules, structural deformation, collapse, and disintegration that may have a negative impact on the treatment effect of sewage and wastewater during long-term operation of the equipment.

[0066] The diameter of the mesh column should be slightly smaller than the inner diameter of the reaction tube it is used to fill, so as to ensure that the mesh column basically fills the reaction tube without affecting the installation of the mesh column. The diameter of the mesh column can be controlled by adjusting the thickness and length of the iron or steel plate, the depth of the concave and convex structure, and the diameter of the rolled circle (the spacing between each layer).

[0067] Ozone catalytic oxidation wastewater treatment equipment

[0068] This disclosure provides an ozone catalytic oxidation wastewater treatment device, which includes at least a tubular ozone reactor, which is the core device for ozone catalytic oxidation.

[0069] The tubular ozone reaction device includes a reaction tube, an ozone generator, and a reagent tank. A catalyst module loaded with metal hydroxyl oxides is installed inside the reaction tube. The ozone generator is connected to the reaction tube for inputting ozone. The reagent tank is connected to the reaction tube for inputting reagents that participate in the ozone catalytic oxidation reaction. Several reaction tubes are connected in series, and the delivery positions of the ozone and reagents are controlled, forming a multi-stage reaction tube. The two ends of this multi-stage reaction tube are respectively used to connect to wastewater and discharge treated wastewater. The multi-stage reaction tube is divided into n levels, where n≥1, and each level includes at least two reaction tubes. Under normal circumstances, along the direction of wastewater flow, the last reaction pipe in the same stage simultaneously introduces ozone and reagents (in some cases of mild pollution, only ozone may be introduced without reagents), while the other reaction pipes are disconnected from the ozone and reagent supply. In some special cases, such as the treatment of special industrial wastewater with high hardness, high phosphorus concentration, and high heavy metal concentration, the last reaction pipe in the same stage only introduces ozone, while the other reaction pipes only introduce reagents.

[0070] Here, "n levels" refers to the cases where n = 1, 2, 3, ... When n > 1, wastewater can be treated in stages. Using the above arrangement, the catalyst module reacts with oxygen to remove dissolved oxygen from the water, preventing dissolved oxygen from competing with ozone for dissolution. Subsequently, the water reaches the last reaction tube of the same level, where pollutants, ozone, and reagents mix and undergo catalytic oxidation, oxidizing and decomposing pollutants into smaller molecules or harmless substances. When n > 1, this cycle can be repeated, alternating between reduction deoxygenation and catalytic oxidation reactions to form a multi-stage, synergistic treatment process.

[0071] Each of the aforementioned reaction tubes is connected to the ozone generator and the reagent tank. The multi-stage reaction tube shown includes two reaction tubes. An ozone valve is installed in the pipeline between the reaction tube and the ozone generator, and a reagent valve is installed in the pipeline between the reaction tube and the reagent tank. Inlet valves and outlet valves are connected to the pipelines at both ends of the multi-stage reaction tube. The inlet valves and outlet valves are used in conjunction to reverse the direction of the sewage flow at regular intervals. The ozone valves and reagent valves are used in conjunction to alternately and simultaneously input and disconnect ozone and reagent into the same reaction tube, or to alternately input ozone and reagent, depending on the change in the direction of the sewage flow.

[0072] This switching method serves several purposes: first, it prevents the catalyst module from undergoing prolonged reductive deoxygenation reactions, which could lead to surface passivation and affect its deoxygenation efficiency; second, it prevents the loss of catalytic components such as iron hydroxyl oxide and zinc hydroxyl oxide from the catalyst module due to prolonged ozone catalytic oxidation reactions, thus reducing the catalytic oxidation treatment effect. Switching the operating mode ensures that the catalytic components are replenished during the reductive deoxygenation process; and third, as the equipment operates for extended periods, the catalyst module is heavily consumed, causing structural deformation and collapse, producing large fragments and impurities that may clog the reaction pipes, reduce water flow, and create stagnant water zones. Therefore, reverse water flow is required to flush the reaction pipes and catalyst module.

[0073] In addition, the equipment may include anoxic-aerobic bioreactors and tower-type ozone reactors. The anoxic-aerobic bioreactor is used for pre-treatment of wastewater, employing common AO, A2O, MBR, or combinations thereof processes. The tower-type ozone reactor is used to consume excess ozone and further purify the water.

[0074] Preferably, the anoxic-aerobic bioreactor includes an anoxic tank and an aerobic tank; wastewater is introduced into the upper part of the anoxic tank and communicates with the aerobic tank at the lower part; a membrane module is installed in the middle and / or upper part of the aerobic tank, and the wastewater treated by the membrane module is transported to the tubular ozone reactor through a pipeline. This anoxic-aerobic bioreactor adopts the AO / MBR process, first undergoing conventional AO process, and then undergoing MBR (membrane bioreactor) treatment.

[0075] Preferably, the tower-type ozone reactor includes a reaction tower, which contains catalyst packing and a dissolved gas release device; the dissolved gas release device is located below the catalyst packing and is connected to the treated wastewater of the tubular ozone reactor via a pipeline; the reaction tower above the catalyst packing has an outlet for discharging the treated wastewater. The catalyst packing is preferably prepared using or by referencing the manufacturing methods and steps of the catalyst module.

[0076] In addition, the equipment may also include other components and devices, such as various pumps (chemical pumps, booster pumps, return pumps) installed on the pipeline, various instruments (flow meters, ozone concentration meters, pressure gauges), various valves, blowers for aeration, etc. To provide a detailed description of the wastewater treatment equipment and process disclosed herein, specific embodiments are described below:

[0077] Example 1

[0078] refer to Figures 1-5The ozone catalytic oxidation wastewater treatment equipment includes a tubular ozone reactor 1, a tower ozone reactor 2, and an anoxic / aerobic bioreactor (AO / MBR) 3. The anoxic / aerobic bioreactor 3 contains an anoxic tank 3-1 and an aerobic tank 3-2, which are connected. The upper and middle sections of the aerobic tank 3-2 contain membrane modules 3-3, and the bottom of the aerobic tank 3-2 contains a return pump 3-4. The membrane modules 3-3 are connected to a blower 3-5. The tubular ozone reactor 1 includes a reaction pipe and an influent... The system includes a water tank 1-11, an ozone generator 1-12, and a reagent water tank 1-13. The reaction tubes are divided into two groups: Group B and Group A. Group B includes: Group B No. 1 reaction tube 1-1, Group B No. 2 reaction tube 1-3, and Group B No. 3 reaction tube 1-5. Group A includes: Group A No. 1 reaction tube 1-2, Group A No. 2 reaction tube 1-4, and Group A No. 3 reaction tube 1-6. The tower ozone reactor 2 includes a tower reaction tower 2-1, catalyst packing 2-2, and dissolved gas release device 2-3.

[0079] The wastewater to be treated first reaches the AO / MBR 3, where it undergoes biochemical treatment through anaerobic, anoxic, and aerobic microbial metabolism. Nitrogenous and phosphorus-containing substances, as well as biodegradable COD pollutants, are removed from the water. The water then passes through a microporous membrane to filter out suspended solids, including activated sludge. After biochemical treatment, the water discharged from the AO / MBR 3 reaches the tubular ozone reactor 1, where it undergoes high-efficiency ozone catalytic oxidation treatment. Non-biodegradable high-molecular-weight and stable COD pollutants are decomposed into small molecules or harmless substances. Finally, the water reaches the tower ozone reactor 2, where ozone from microbubbles and a catalyst work together to complete water purification. The remaining low concentration of COD pollutants in the water are completely decomposed and converted into harmless substances, and the effluent meets discharge standards.

[0080] The inlet water tank 1-11 and its outlet are connected to the inlet of the inlet booster pump 1-14. The outlet of the inlet booster pump 1-14 is connected to the inlet pipe 1-8. An inlet flow meter 1-20 is installed on the inlet pipe 1-8. The outlet of the inlet flow meter 1-20 is equipped with a tee, which connects to the ends of reaction pipe 1-1 of group B and reaction pipe 1-6 of group A via pipes. The inlet flow meter 1-20 is connected to reaction pipe 1-1 of group B and reaction pipe 1-6 of group A, and the reaction pipe 1-1 of group B is connected to the end of reaction pipe 1-6 of group A. The pipes of reaction tube 1-6 (group 3) are equipped with inlet valves 1-26 (group A) and 1-27 (group B). One end of the return pipe 1-9 is connected to the inlet water tank 1-11, and the other end of the return pipe 1-9 is connected via a tee to the ends of reaction tube 1-1 (group B) and reaction tube 1-6 (group A). ​​Return pipes 1-9 from inlet water tank 1-11 to the ends of reaction tube 1-1 (group B) and reaction tube 1-6 (group A) are equipped with return valves 1-28 (group B) and 1-29 (group A). ​​In this embodiment, the reaction tubes are divided into two groups, A and B, which alternately perform catalytic oxidation and reductive deoxygenation reactions.

[0081] Reactor tubes 1-1 (Group B), 1-2 (Group A), 1-3 (Group B), 1-4 (Group A), 1-5 (Group B), and 1-6 (Group A) are connected in series by pipes. Each of these reactors contains a catalyst module 1-7. Reactor tubes 1-3 (Group B), 1-4 (Group A), 1-5 (Group B), and 1-6 (Group A) are connected in series by pipes. Pressure gauge 1-38 is installed at the connecting pipe between them; one end of the outlet pipe 1-10 is connected to the tower ozone reactor 2, and the other end is connected to the ends of reaction pipe 1-1 of group B and reaction pipe 1-6 of group A via a tee. The outlet pipe 1-10 from the end of reaction pipe 1-1 of group B and reaction pipe 1-6 of group A to the outlet pipe 1-10 of tower ozone reactor 2 is equipped with outlet valve 1-30 of group B and outlet valve 1-31 of group A, respectively. The outlet pipe 1-10 is equipped with outlet flow meter 1-21 and outlet ozone concentration meter 1-37.

[0082] The outlet of ozone generator 1-12 is connected to the inlet of initial ozone concentration meter 1-36. The outlet of initial ozone concentration meter 1-36 is connected to one end of ozone pipe 1-17 (group B) and ozone pipe 1-16 (group A). ​​The other end of ozone pipe 1-17 (group B) leads to the interior of reaction tube 1-1 (group B), reaction tube 1-3 (group B), and reaction tube 1-5 (group B). The other end of ozone pipe 1-16 (group A) leads to the interior of reaction tube 1-2 (group A), reaction tube 1-4 (group A), and reaction tube 1-6 (group A). ​​Ozone pipes 1-17 (group B) and 1-16 (group A) are connected in parallel. Ozone pipe 1-17 (group B) is equipped with ozone flow meter 1-23 (group B) and ozone valve 1-33 (group B). Ozone pipe 1-16 (group A) is equipped with ozone flow meter 1-22 (group A) and ozone valve 1-32 (group A).

[0083] The outlet of the reagent tank 1-13 is connected to the inlet of the reagent pump 1-15 via a pipe. The outlet of the reagent pump 1-15 is connected to one end of the B group reagent pipe 1-19 and the A group reagent pipe 1-18 respectively. The other end of the B group reagent pipe 1-19 leads to the interior of the B group No. 1 reaction tube 1-1, the B group No. 2 reaction tube 1-3, and the B group No. 3 reaction tube 1-5 respectively. The other end of the A group reagent pipe 1-18 leads to the interior of the A group No. 1 reaction tube 1-2, the A group No. 2 reaction tube 1-4, and the A group No. 3 reaction tube 1-6 respectively. The B group reagent pipe 1-19 and the A group reagent pipe 1-18 are connected in parallel. The B group reagent pipe 1-19 is equipped with a B group reagent flow meter 1-25 and a B group reagent valve 1-35. The A group reagent pipe 1-18 is equipped with an A group reagent flow meter 1-24 and an A group reagent valve 1-34.

[0084] This application employs a tubular reactor with high flow rate, large throughput, and small volume. This not only enhances material mixing, reduces processing load through reflux, and improves reaction rate and depth, but also facilitates equipment disassembly, cleaning, adjustment, and catalyst replacement. The reaction tube volume of this invention is relatively small, and its associated pressurized water pump is correspondingly smaller. Compared to traditional wet oxidation technology, equipment investment and operating costs are significantly reduced, and a high-pressure environment is easier to achieve.

[0085] The length of the reaction tube is set to 3.5m to 6.5m, which can be filled with catalyst modules 1-7. The inner diameter of the reaction tube is set to 20cm to 40cm. The reaction tube, water inlet pipe 1-8, return pipe 1-9, water outlet pipe 1-10, group A ozone pipe 1-16, group B ozone pipe 1-17, group A reagent pipe 1-18, and group B reagent pipe 1-19 are all made of pressure-resistant and corrosion-resistant materials with a maximum pressure resistance of 1.6MPa to 2.5MPa. The catalyst packing 2-2 is set in the middle of the tower-type reaction tower 2-1. The dissolved gas release device 2-3 is set at the bottom of the tower-type reaction tower 2-1. The water outlet 2-4 is set on the upper side of the tower-type reaction tower 2-1. The air outlet 2-5 and the air inlet 2-6 are set on the top of the tower-type reaction tower 2-1. In this embodiment, the length of all reaction tubes is set to 3.5 to 6.5 m, and the inner diameter of the reaction tubes is set to 20 cm to 40 cm to ensure high flow rate and sufficient reaction residence time.

[0086] The wastewater treatment process of the wastewater treatment equipment in this embodiment includes the following steps:

[0087] S1. After the water to be treated arrives at the anoxic-aerobic bioreactor 3, it first enters the anoxic tank 3-1. After being treated by anaerobic and anoxic microorganisms, it enters the aerobic tank 3-2. Here, after being treated by aerobic microorganisms, the water undergoes solid-liquid separation by the membrane module 3-3. Suspended solids, including activated sludge, are intercepted outside the membrane. The treated water enters the membrane and is then transported by pipeline to the tubular ozone reactor 1. The return pump 3-4 is responsible for returning the activated sludge from the bottom of the aerobic tank 3-2 to the anoxic tank 3-1 for denitrification. After being treated by the anoxic-aerobic bioreactor 3, biodegradable COD substances are removed from the water, and the nitrogen and phosphorus concentrations are treated to meet the standards.

[0088] S2. The water treated by the anoxic-aerobic bioreactor 3 first reaches the inlet tank 1-11 of the tubular ozone reactor 1. After the liquid level in the inlet tank 1-11 reaches the high level, the inlet booster pump 1-14 is started. At this time, the inlet valve 1-26 of group A is open and the inlet valve 1-27 of group B is closed. The water flows through the inlet pipe 1-8 to the front end of the No. 1 reaction pipe 1-1 of group B. The water flows through the No. 1 reaction pipe 1-1 of group B, the No. 1 reaction pipe 1-2 of group A, and the No. 2 reaction pipe 1-1 of group B in sequence. Reactor tubes 1-3, 2-4 (Group A), 3-5 (Group B), and 3-6 (Group A) flow out from the front end of 3-6 (Group A). ​​At this time, 1-29 (Group A return valve) and 1-31 (Group A outlet valve) are open, while 1-28 (Group B return valve) and 1-30 (Group B outlet valve) are closed. Part of the water flows back to the inlet tank 1-11 through return pipe 1-9, and the other part flows to the tower ozone reactor 2 through outlet pipe 1-10.

[0089] S3. Water flows sequentially through reaction pipe 1-1 of group B, reaction pipe 1-2 of group A, reaction pipe 1-3 of group B, reaction pipe 1-4 of group A, reaction pipe 1-5 of group B, and reaction pipe 1-6 of group A. Ozone valve 1-33 of group B is closed, ozone valve 1-32 of group A is open, and ozone generator 1-12 is turned on. The generated ozone gas is transported through ozone pipeline 1-16 of group A to reaction pipe 1-2 of group A, reaction pipe 1-4 of group A, and reaction pipe 1-6 of group A. Chemical valve 1-35 of group B is closed, and chemical valve 1-34 of group A is open. The chemical in chemical tank 1-13 is transported through chemical pump 1-15 and chemical pipeline 1-18 of group A to reaction pipe 1-2 of group A, reaction pipe 1-4 of group A, and reaction pipe 1-6 of group A.

[0090] The ozone generators 1-12 are preferably pure oxygen source or oxygen-enriched source ozone generators to increase the ozone concentration entering the reaction tube and reduce the entry of other non-reaction gases (such as nitrogen, carbon dioxide, etc.) into the reaction tube. On the one hand, high concentration and high solubility of ozone can improve the efficiency of catalytic oxidation reaction; on the other hand, it can avoid non-reaction gases crowding out the water flow volume and ozone solubility in the reaction tube, thus reducing the contact efficiency between reactants. Preferably, the ozone concentration in the gas generated by the ozone generators 1-12 should be greater than 100 mg / L. Preferably, the ozone dosage is determined based on the COD concentration to be removed from the water body, and the ozone to COD mass ratio (O3 / COD) is 0.5 to 1.5.

[0091] The reagents contained in the reagent tanks 1-13 are preferably liquid reagents with oxidizing properties, such as hydrogen peroxide and sodium hypochlorite. The added reagents will directly or indirectly participate in the ozone catalytic oxidation reaction, thereby enhancing the oxidizing power of the reaction and effectively oxidizing and removing chemically stable pollutants.

[0092] The time it takes for water to pass through each reaction tube is the hydraulic retention time (HRT), which is preferably 10 to 30 minutes. The inflow rate through the inlet pipes 1-8 is calculated from the HRT. The amount of water returning through the return pipes 1-9 should be 30% to 70% of the amount of water entering through the inlet pipes 1-8, in order to control the concentration of pollutants in the water entering the reaction tubes and improve the reaction efficiency.

[0093] S4. The water first reaches reaction tube 1-1 of group B, where it undergoes a reduction reaction with oxygen via catalyst module 1-7, removing dissolved oxygen. The water then reaches reaction tube 1-2 of group A, where pollutants, ozone, and reagents undergo a catalytic oxidation reaction, oxidizing and decomposing pollutants into smaller molecules and harmless substances. The water then reaches reaction tube 1-3 of group B, where it again undergoes a reduction reaction with oxygen via catalyst module 1-7, removing dissolved oxygen. Finally, a catalytic oxidation reaction occurs in reaction tube 1-4 of group A, alternating between reduction deoxygenation and catalytic oxidation reactions.

[0094] Steps S5 and S4 are the operating modes of reduction deoxygenation in group B reaction tubes and catalytic oxidation in group A reaction tubes. After a preset time, the operating mode is switched to reduction deoxygenation in group A reaction tubes and catalytic oxidation in group B reaction tubes.

[0095] In the two operating modes, the water flow direction in the reaction tube is opposite; the interval between switching between operating modes is preferably 100 to 200 times the hydraulic residence time of the water in the reaction tube; in addition, it is necessary to observe or monitor the operating status of the reaction tube at all times, and switch the operating mode in time when encountering situations such as reduced water flow, increased pressure, or reduced COD removal rate.

[0096] S6. Water treated by the tubular ozone reactor 1 flows through the outlet pipe 1-10 to the tower ozone reactor 2. It is then released into the tower reactor 2-1 by the dissolved gas release device 2-3. Inside the tubular ozone reactor 1, the gas and water are in a high-pressure dissolved gas liquid phase. After being released by the dissolved gas release device 2-3, the gas is released from the liquid phase in the form of tiny bubbles. The water and gas move from bottom to top within the tower reactor 2-1, passing through the catalyst packing 2-2. Residual reagents, pollutants, and ozone in the water and gas undergo a catalytic oxidation reaction with the catalyst packing 2-2. This process removes residual pollutants from the water, ensuring stable effluent quality; it also consumes residual reagents and ozone in the water and gas, preventing secondary pollution.

[0097] S7. The final treated water reaches the upper part of the tower reactor 2-1 and is discharged from the outlet 2-4.

[0098] The treated gas is mainly composed of oxygen. It reaches the upper part of the tower reactor 2-1 and is drawn by the blower 3-5 through the outlet 2-5 to the bottom of the membrane module 3-3 for aeration. On the one hand, the high concentration of oxygen can greatly increase the dissolved oxygen concentration of the aerobic tank 3-2; on the other hand, it flushes and cleans the membrane module 3-3, prevents membrane fouling, and forms an aerobic biochemical treatment environment. The function of the inlet 2-6 is to supplement the gas volume delivered to the membrane module 3-3 and balance the gas pressure inside and outside the tower reactor 2-1.

[0099] Ozone catalytic oxidation wastewater treatment method

[0100] The wastewater treatment method disclosed herein utilizes the aforementioned ozone catalytic oxidation wastewater treatment equipment during the wastewater treatment process. At least a tubular ozone reactor is used in the wastewater treatment process. This tubular ozone reactor can be connected to conventional wastewater treatment equipment for further ozone catalytic oxidation. Preferably, the anoxic-aerobic bioreactor and tower ozone reactor disclosed herein can also be used. The wastewater to be treated first enters the anoxic-aerobic bioreactor. The first step is anaerobic and anoxic microbial metabolic treatment in the anoxic tank, the second step is aerobic microbial metabolic treatment in the aerobic tank, and the third step is solid-liquid separation through a membrane module. Then, the wastewater enters the tubular ozone reactor, where reduction deoxygenation and catalytic oxidation reactions alternately occur in multi-stage reaction tubes. Finally, it enters the tower ozone reactor, where ozone from microbubbles and a catalyst work together to complete water purification, consuming excess ozone and reagents.

[0101] The ozone catalytic oxidation wastewater treatment method disclosed herein is applicable to various types of wastewater, and will be described in detail below through specific embodiments:

[0102] Example 2

[0103] The equipment and process described in this embodiment are applied to the treatment of production wastewater from a pharmaceutical factory, with a treatment capacity of 500 cubic meters per day. This embodiment includes a screen and an anaerobic reactor preceding the AO / MBR.

[0104] The wastewater to be treated first reaches the bar screen device, which is equipped with a coarse bar and a fine bar with gaps of 20-30cm and 5-10mm respectively, to filter out large particles of solid matter in the water.

[0105] After the removal of large particulate solids, the water enters the anaerobic reactor, specifically an upflow anaerobic sludge bioreactor (UASB). Through the reproduction and metabolism of anaerobic microorganisms, organic pollutants are converted into harmless nitrogen, carbon dioxide, and water. At this point, most of the organic pollutants in the water are removed. The COD (chemical oxygen demand) concentration of the influent and effluent is used as the evaluation index. The COD removal rate reaches 75% to 90%, and the remaining COD concentration should be controlled at 300 to 500 mg / L to serve as the carbon source for the subsequent biochemical reactions in the AO / MBR.

[0106] When water enters the AO / MBR, it undergoes biochemical treatment through anaerobic, anoxic, and aerobic microbial metabolism. Nitrogenous and phosphorus-containing substances, as well as biodegradable COD pollutants, are removed. The water then passes through a microporous membrane filter, which filters out suspended solids, including activated sludge, completing the nitrogen and phosphorus removal process. The dissolved oxygen (DO) concentration in the anoxic tank is controlled to be less than 0.2 mg / L, and the DO concentration in the aerobic tank is controlled to be greater than 2 mg / L. The ROV ratio of the AO / MBR is 2–4, and the pore size of the membrane module is 0.2–1.0 μm.

[0107] Water discharged from the AO / MBR reaches the tubular ozone reactor, where it undergoes high-efficiency ozone catalytic oxidation treatment. Non-biodegradable high-molecular-weight, stable COD pollutants are decomposed into smaller molecules or harmless substances. The tubular ozone reactor has two groups of reaction tubes, A and B, with four tubes in each group (a total of eight tubes). Each tube is 0.4m in diameter and 5.5m in length, containing five catalyst modules. The controlled operating parameters for the tubular ozone reactor are: pressure control at 1.75MPa, HRT at 10min, and influent flow rate at 36m³ / min. 3 / h, reflux ratio of 30%, switching time between group A and group B reaction tube operation modes is 30h. No reagents added. Ozone concentration is 100mg / L, ozone dosage is 100g / m³. 3 .

[0108] The raw material for the catalyst module is a 1mm thick, 1m wide, and 9m long carbon steel plate, which is cut and stamped to a depth of 1.0mm. It is then rolled and fixed. After cleaning with 45% ethanol and 5% sodium hydroxide, it is soaked in 0.5% zinc chloride solution for 2 hours, then removed and cured at 150℃ for 0.5 hours. Finally, it is immersed in 10% hydrogen peroxide, removed, and air-dried naturally to obtain the catalyst module.

[0109] The water enters the tower ozone reactor, where microbubble ozone and a catalyst work together to complete the final purification of the water. The remaining low concentrations of COD pollutants in the water are completely decomposed and transformed into harmless substances, resulting in effluent that meets discharge standards. The tower ozone reactor is 7m high and 3.5m in diameter, with the catalyst filling 65% of its volume.

[0110] The influent and effluent water quality indicators for each process section in this embodiment are shown in Table 1 below:

[0111] Table 1. Water quality indicators of influent and effluent for each process section in Example 2

[0112]

[0113] As shown in Table 1 above, the effluent from the tubular ozone reactor process section of the present invention has reached the Class I pollutant discharge standard requirements of the Integrated Wastewater Discharge Standard (GB 8978-1996). Further treatment by the tower ozone reactor reduces the COD concentration to an even lower level, ensuring that the process effluent consistently meets the standards.

[0114] Example 3

[0115] The equipment and process in this embodiment are applied to the treatment of wastewater from a liquor brewing industry, with a treatment capacity of 1200 cubic meters per day. This embodiment includes a bar screen and an anaerobic reactor in the AO / MBR; the AO / MBR has two stages of AO process.

[0116] The wastewater to be treated first reaches the bar screen device, which is a barrel-type rotary filter with a gap of 5mm, to filter out larger particles of grain residue and other solid matter in the water.

[0117] After the removal of large-particle solids, the water enters the anaerobic reactor, which consists of two parallel upflow anaerobic sludge bioreactors (UASB). Through the reproduction and metabolism of anaerobic microorganisms, organic pollutants are converted into harmless nitrogen, carbon dioxide, and water. A high concentration of methane is also produced; this gas is collected and then ignited for emission. After treatment in the anaerobic reactor, most of the organic pollutants in the water are removed. Using the COD (chemical oxygen demand) concentration of the influent and effluent as an indicator, the COD removal rate should reach 80%–90%, and the remaining COD concentration should be controlled at 500–900 mg / L to serve as the carbon source for subsequent biochemical reactions in the AO / MBR.

[0118] When water enters the AO / MBR, it undergoes biochemical treatment through anaerobic, anoxic, and aerobic microbial metabolism. Nitrogenous and phosphorus-containing substances, as well as biodegradable COD pollutants, are removed. The water then passes through a microporous membrane filter, which filters out suspended solids, including activated sludge, completing the nitrogen and phosphorus removal process. The AO / MBR consists of two AO stages connected in series, with a microporous membrane filter at the end. The dissolved oxygen (DO) concentration in the first-stage anoxic tank is controlled to be less than 0.5 mg / L, and the DO concentration in the first-stage aerobic tank is controlled to be within the range of 1–2 mg / L. The DO concentration in the second-stage anoxic tank is controlled to be less than 0.1 mg / L, and the DO concentration in the first-stage aerobic tank is controlled to be greater than 2 mg / L. The AO / MBR recirculation volume ratio is 2, and the membrane module pore size is 0.2–1.0 μm.

[0119] It is worth noting that after treatment by the primary AO process, the biodegradable COD in the water is insufficient to provide a carbon source for nitrogen and phosphorus removal in the secondary AO process. Therefore, about 30% of the anaerobic reactor effluent is added to the influent of the secondary AO process to supplement the carbon source and ensure normal microbial nitrogen and phosphorus removal metabolism in the secondary AO process.

[0120] Water discharged from the AO / MBR reaches the tubular ozone reactor, where it undergoes high-efficiency ozone catalytic oxidation treatment. Non-biodegradable high-molecular-weight, stable COD pollutants are decomposed into smaller molecules or harmless substances. The tubular ozone reactor has two groups of reaction tubes, A and B, each with 13 tubes (a total of 26 tubes). Each tube is 0.4m in diameter and 6.5m in length, containing 6 catalyst modules. The controlled operating parameters for the tubular ozone reactor are: pressure control at 2.2MPa, HRT at 10min, and influent flow rate at 120m³ / min. 3 The reflux rate is 50%, and the switching time between the A and B group reaction tubes is 30 hours. The selected reagent is 15% hydrogen peroxide, with a dosage of 300 ml / m³. 3 It was added simultaneously with ozone into the same set of reaction tubes. The ozone concentration was 100 mg / L, and the ozone dosage was 110 g / m³. 3 .

[0121] The raw material for the catalyst module is a 1mm thick, 1m wide, and 10m long carbon steel plate, which is cut and stamped to a depth of 1.0mm. It is then rolled and fixed. After cleaning with 45% ethanol and 5% sodium hydroxide, it is soaked in 2% zinc chloride solution for 2 hours, then removed and cured at 150℃ for 1 hour. It is then immersed in 20% hydrogen peroxide, removed, and air-dried naturally to obtain the catalyst module.

[0122] Finally, the water enters the tower ozone reactor, where the combined action of microbubble ozone and catalyst completes the final purification of the water. The remaining low concentrations of COD pollutants in the water are completely decomposed and transformed into harmless substances, resulting in effluent that meets discharge standards. Two tower ozone reactors are installed in parallel, each 7m high and 3.5m in diameter; the catalyst fills 70% of the tower ozone reactor's volume.

[0123] The influent and effluent water quality indicators for each process section in this embodiment are shown in Table 2 below:

[0124] Table 2. Influent and effluent water quality indicators for each process section in Example 3

[0125]

[0126] As shown in Table 2 above, the effluent quality achieved by using the equipment and process of this invention meets the pollutant discharge standards of the "Emission Standard of Water Pollutants for Fermented Alcohol and Baijiu Industry" (GB 27631-2011). Specifically, the tubular ozone reactor exhibits excellent COD pollutant removal efficiency in the advanced treatment process, capable of decomposing and removing pollutants that are difficult to treat biochemically.

[0127] Example 4

[0128] For the treatment of special industrial wastewater with high hardness, high phosphorus concentration, and high heavy metal concentration, such as chemical and metallurgical wastewater, in the tubular ozone reactor, the reagents in the reagent tank can be reducing agents, such as lime, ferrous sulfate, and sodium metabisulfite, which are added to different groups of reaction tubes along with ozone. For example, ozone is added to group A reaction tubes for catalytic oxidation, while reducing agents are added to group B reaction tubes for reduction and deoxygenation.

[0129] The effects of adding reducing agents are mainly twofold: first, they can consume and remove dissolved oxygen in the water, preventing it from competing with ozone for dissolution; second, they can react with some polar ions or molecules, organic matter, etc. in the water to generate solid substances, which are separated from the liquid phase. These solid substances naturally settle after reaching the tower ozone reactor from the tubular ozone reactor and are removed from the water through sludge discharge.

[0130] It should be understood that all the above embodiments are exemplary and not restrictive. Various modifications or variations made by those skilled in the art to the specific embodiments described above under the concept of this disclosure should be within the protection scope of this disclosure.

Claims

1. A method for treating wastewater by catalytic ozonation, characterized by: An ozone catalytic oxidation wastewater treatment device is used in the wastewater treatment process. This device includes a tubular ozone reactor, comprising a reaction tube, an ozone generator, and a reagent tank. The reaction tube contains a catalyst module, which is a perforated plate loaded with metal hydroxyl oxides. The perforated plate is an iron or steel plate with mesh openings, wound several times in a spiral direction, ultimately forming a cylindrical shape that can fill the reaction tube. The ozone generator is connected to the reaction tube via a pipe for inputting ozone. The reagent tank is also connected to the reaction tube via a pipe. The reaction tubes are configured to input reagents that participate in the ozone catalytic oxidation reaction. Several reaction tubes are connected in series, and the delivery positions of ozone and reagents are controlled, so that the series-connected reaction tubes form a multi-stage reaction tube. The two ends of the multi-stage reaction tube are respectively used to connect to sewage and discharge treated sewage. The multi-stage reaction tube is divided into n levels, where n≥1. Each level includes two reaction tubes. Along the direction of sewage flow, the last reaction tube in the same level simultaneously inputs ozone and reagents or only inputs ozone, while the other reaction tubes are disconnected to input ozone and reagents or only input reagents. Each of the aforementioned reaction tubes is connected to the ozone generator and the reagent tank. An ozone valve is installed in the pipeline between the reaction tube and the ozone generator, and a reagent valve is installed in the pipeline between the reaction tube and the reagent tank. Inlet and outlet valves are connected to the pipelines at both ends of each multi-stage reaction tube. The inlet and outlet valves work together to reverse the flow direction of the wastewater at regular intervals. The ozone and reagent valves work together to alternately and simultaneously input and disconnect ozone and reagent into the same reaction tube, or to alternately input ozone and reagent, depending on the change in the flow direction of the wastewater.

2. The ozone catalytic oxidation wastewater treatment method according to claim 1, characterized in that, The preparation method of the catalyst module includes: A perforated iron or steel plate is wound several times in a spiral direction to produce a perforated column. Clean the mesh column by first soaking it in a 0.5-2 wt% zinc chloride solution for 1-2 hours, then removing it and placing it in a vacuum or a closed high-temperature furnace filled with inert gas, and calcining it at 150-200°C for 0.5-1 hours. The mesh column is removed from the high-temperature furnace and placed in 10-30 wt% hydrogen peroxide solution with a pH of 3-6 when its surface temperature drops to 50-100°C. After the violent reaction subsides, the column is removed and dried to obtain the catalyst module.

3. The ozone catalytic oxidation wastewater treatment method according to claim 1 or 2, characterized in that: The perforated plate is made of conventional iron mesh or steel mesh; Alternatively, the perforated plate can be manufactured by a method comprising: Cutting slits are made on the surface of an iron plate or steel plate. The cutting slits include a first cutting slit and a second cutting slit, which are respectively opened along the length direction and the width direction of the iron plate or steel plate. The iron or steel plate is stamped, and the surface of the stamping die is provided with several rows of concave and convex structures. The concave and convex structures include continuously alternating protrusions and depressions, and the protrusions and depressions are distributed in correspondence with the grid formed by the cutting seam. The stamped iron or steel plate also forms a concave and convex structure, and holes are formed between adjacent protrusions and depressions in its concave and convex structure.

4. The ozone catalytic oxidation wastewater treatment method according to claim 2, characterized in that, The cleaning method includes: First, place the mesh column in a 45-90 wt% ethanol solution, soak for 2-6 hours, then remove it and rinse off the residual ethanol. The mesh column is then placed in a 5-10 wt% sodium hydroxide solution and soaked for 2-6 hours before being removed and rinsed to remove any residual sodium hydroxide.

5. The ozone catalytic oxidation wastewater treatment method according to claim 1, characterized in that: The ozone catalytic oxidation wastewater treatment equipment also includes anoxic and aerobic bioreactors and tower ozone reactors; The anoxic-aerobic bioreactor includes an anoxic tank and an aerobic tank; wastewater is introduced into the upper part of the anoxic tank and is connected to the aerobic tank at the lower part; a membrane module is provided in the middle and / or upper part of the aerobic tank, and the wastewater treated by the membrane module is transported to the tubular ozone reactor through a pipeline. The tower-type ozone reactor includes a reaction tower, which contains a catalyst packing and a dissolved gas release device. The dissolved gas release device is located below the catalyst packing and is connected to the wastewater treated by the tubular ozone reactor through a pipeline. The reaction tower above the catalyst packing is provided with an outlet for discharging the treated wastewater.

6. The ozone catalytic oxidation wastewater treatment method according to claim 5, characterized in that: The top of the reaction tower is provided with an air outlet and an air inlet; the air outlet pipe is connected to the aerobic tank.

7. The ozone catalytic oxidation wastewater treatment method according to claim 1, characterized in that: The pipe between the reaction tube and the ozone generator or reagent tank extends into the reaction tube.

Images