Fixed bed fenton-like reaction device

Abstract

The utility model discloses a fixed bed fenton reaction device, the device is closed vertical three area structure, adopts pipeline mixer and tangential nozzle to form cyclone, and gas collecting hood collects waste gas and is equipped with from bottom to top backwash loop, and catalyst fills 3~5mm porous magnetic particle, and specific surface area is 200~300m 2 / g, porosity is 70~80%, and can be magnetically selected recovery, under the condition of near neutral pH 5~7 when the device runs, H2O2 is added according to 1~1.5 times of inflow water COD, catalyst stays 30~60min, can realize efficient degradation to high salt high chlorine refractory organic wastewater, reduce iron mud production, easy to backwash recovery and reduce operation cost, has the engineering popularization value, and operation is stable and reliable.

Description

Technical Field

[0001] This utility model belongs to the field of wastewater treatment technology, specifically relating to a fixed-bed Fenton reactor. Background Technology

[0002] Industrial production processes generate large amounts of wastewater with high salt content and containing recalcitrant organic matter, which cannot be directly introduced into biological treatment units and requires pretreatment.

[0003] Fenton oxidation is a typical advanced oxidation technology. The hydroxyl radicals (·OH) generated during the oxidation process act as strong oxidants, effectively degrading organic pollutants in wastewater. Traditionally, Fe... 2+ Ferrous sulfate will be oxidized to Fe. 3+ This process generates iron sludge Fe(OH)3, leading to iron salt consumption and sludge problems, and also results in a narrow operating pH range. Heterogeneous Fenton-like systems utilize solid catalysts to replace soluble iron ions (such as Fe) in homogeneous systems. 2+ This effectively broadens the applicable pH range and greatly reduces secondary pollution caused by iron sludge, showing broad application prospects.

[0004] Utility model patent ZL 201920688565.1 discloses an integrated fixed-bed Fenton device for industrial wastewater treatment. The middle section is a trapezoidal fixed-bed reactor, and the lower pH adjustment tank is equipped with a spiral agitator. The trapezoidal device allows sludge to be pumped away from the bottom of the middle section. Although this reactor and adjustment tank are combined in a design that saves space, it greatly increases the difficulty of maintenance in case of agitator failure in the adjustment tank, resulting in poor feasibility for engineering applications.

[0005] Invention patent ZL202110342908.0 relates to a high-efficiency heterogeneous Fenton reactor for high-salt and recalcitrant wastewater and its treatment method for high-salt and recalcitrant wastewater. However, it requires external circulating water to be injected into the jacket for temperature control, which increases the complexity of the system and makes it difficult to apply in engineering. Utility Model Content

[0006] To address the problems of large iron sludge production, narrow pH range, and poor adaptability to high-salt / high-chlorine recalcitrant wastewater in traditional Fenton processes, this invention aims to provide a fixed-bed Fenton reactor. It features a three-section structure within a sealed vertical shell: an inlet mixing zone, a catalyst packing zone, and an effluent zone. On the inlet side, a pipe mixer and tangentially inclined nozzles create a swirling flow to enhance the contact between H2O2 and the aqueous phase. A gas collection component at the top of the device centrally collects reaction waste gas. Furthermore, it is equipped with a bottom-up backwashing loop using the effluent as the water source, online monitoring and interlocking control, and uses porous magnetic particles as the fixed-bed packing material to achieve efficient pretreatment of high-salt, high-chlorine, recalcitrant organic wastewater under near-neutral pH conditions. This synergistic design significantly improves degradation efficiency, reduces iron sludge production and operating costs, and facilitates engineering applications.

[0007] To achieve the above objectives, this utility model provides a fixed-bed Fenton reactor, comprising a sealed shell, wherein an inlet mixing zone, a catalyst packing zone, and an outlet zone are formed sequentially from bottom to top inside the shell;

[0008] The water inlet mixing zone is connected to the water inlet pipeline, which is connected to the H2O2 dosing branch via a pipeline mixer. The outlet of the pipeline mixer is connected to multiple nozzles arranged tangentially and obliquely relative to the inner wall of the shell via a distribution pipe to form a swirling flow in the water inlet mixing zone.

[0009] The catalyst packing region supports a heterogeneous Fenton-like catalyst.

[0010] The water outlet area is equipped with an annular water outlet trough and is connected to the water outlet pipeline;

[0011] A gas collection component is installed above the catalyst packing area and connected to an external waste gas treatment system via a waste gas emission outlet;

[0012] The reaction device is also equipped with a backwash circuit with effluent as the water source. The backwash circuit includes a backwash water pump connected to the annular effluent tank, a backwash water inlet located at the bottom of the shell, and a backwash water outlet tank located in the effluent area, below the annular effluent tank and fixed to the inner wall of the shell. The bottom edge of the backwash water outlet tank is inclined to the center of the shell, and works with the gas collecting component to guide the rising gas during the reaction to the gas collecting component and discharge it through the exhaust port.

[0013] In some technical solutions, the nozzles are arranged at equal intervals along the circumference of the housing and staggered in phase, and the angle between the nozzle spray direction and the tangential direction of the inner wall of the housing is 30 to 45°.

[0014] In some technical solutions, the catalyst packing zone is supported by a water distribution baffle, and the catalyst filling rate is 50-70% of the total volume of the reaction device.

[0015] In some technical solutions, a water outlet weir is provided on the inner side of the annular water outlet channel, and the water outlet weir is a triangular weir or a trapezoidal weir.

[0016] In some technical solutions, the gas collecting component is an inverted trumpet-shaped gas collecting hood, located on the shell axis above the catalyst packing area.

[0017] In some technical solutions, an acid dosing port and an online pH monitoring unit for the influent are installed on the side of the influent mixing zone, connected to the zone; an online COD monitoring unit for the influent is installed on the influent pipeline; online pH and ORP monitoring units for the effluent are installed in the effluent zone, and an online COD monitoring unit for the effluent is installed on the effluent pipeline; and,

[0018] The aforementioned online monitoring components are electrically connected to their respective actuators to form interlocking controls, including: influent COD and H2O2 dosing interlock, influent pH and acid dosing interlock, and effluent COD and effluent valve interlock.

[0019] In some technical solutions, the backwash circuit flows through the catalyst packing area from bottom to top, and the backwash water is collected in the backwash water outlet tank and discharged from the backwash water discharge port.

[0020] In some technical solutions, the heterogeneous Fenton catalyst is a magnetic particle catalyst with a particle size of 3-5 mm, a porous structure, and is suitable for backwashing and recovery.

[0021] In some technical solutions, the magnetic particle catalyst is prepared by sequentially reducing, magnetically separating, mixing with an inorganic binder, and calcining high-iron ash slag.

[0022] In some technical solutions, multiple reaction units are connected in parallel so that the remaining reaction units can maintain continuous water intake operation of the system when any one unit is backwashed or shut down for maintenance.

[0023] The present invention, by adopting the above technical solution, has at least the following beneficial effects:

[0024] 1. This utility model adopts a closed vertical three-zone structure (inlet mixing zone—catalyst packing zone—outlet water zone), and a pipeline mixer and multiple tangential / inclined nozzles are configured in the inlet mixing zone to form a strong swirling flow. This mass transfer enhancement design enables H2O2 to mix quickly and thoroughly with the inlet water and distribute the mixture evenly to the catalyst packing layer, thereby shortening the initial reaction time and increasing the treatment intensity per unit volume; at the same time, the combination of swirling flow and water distribution baffle helps to suppress local short circuits and blockages in the packing layer, ensuring the overall utilization rate of the catalyst layer; the gas collection component set at the top, in conjunction with the annular water outlet trough / water outlet weir, can realize the centralized collection of volatile organic compounds or gases in the reaction and send them to the waste gas treatment system, reducing secondary pollution;

[0025] 2. This invention monitors influent COD, influent pH, effluent COD, effluent pH, and ORP online, and interlocks these monitoring signals with the H2O2, acid (HCl) dosing device, and effluent valve for control (e.g., automatically adjusting the H2O2 dosage to 1–1.5 times the influent COD, controlling the influent pH within a set range of 5–7 with acid dosing, and automatically refluxing the effluent if the COD is below standard). This significantly reduces reagent waste and manual adjustment intensity while ensuring reaction efficiency, thereby reducing operating costs and improving system stability. Furthermore, the catalyst of this invention can efficiently catalyze ·OH generation even under near-neutral pH conditions (avoiding the strong dependence of traditional Fenton reactors on low pH), resulting in significant economic advantages in acid and alkali consumption and sludge disposal.

[0026] 3. This utility model designs a bottom-up backwashing circuit with effluent as the water source. The backwash water is pumped from bottom to top through the catalyst packing area and discharged through a backwash water outlet tank fixed around the inner wall of the shell. This backwashing system (preferably with a cycle of 3-4 months and a backwashing intensity of 10-15 L / m) 2 (Backwashing time 15–20 min) can effectively remove adsorbent sludge or flocculated pollutants without removing the catalyst layer, restore water permeability and extend the operating cycle. With the arrangement of multiple units operating in parallel, the system can ensure continuous processing capacity when a single unit is backwashed or shut down for maintenance, thereby improving the reliability and applicability of the project.

[0027] 4. This invention uses high-iron industrial ash as a catalyst raw material. Under reducing conditions, the iron in the ash is converted into magnetic iron oxide, which is then enriched by magnetic separation to form porous magnetic particles. This constructs a heterogeneous fixed-bed Fenton system for the pretreatment of high-salt, high-chlorine, and recalcitrant organic wastewater. This approach achieves solid waste resource utilization and reduces material costs. Furthermore, by fixing the iron phase on the catalyst, it avoids the generation of large amounts of iron sludge in conventional homogeneous Fenton reactions, thus significantly reducing the burden of sludge disposal and improving the system's environmental friendliness and economic efficiency.

[0028] 5. The particulate catalyst obtained by this invention is a porous magnetic particle (preferably with a particle size of 3–5 mm and a specific surface area of ​​approximately 200–300 m²). 2 / g (porosity approximately 70–80%), this structure provides a large adsorption area and mass transfer channels, facilitating the migration and enrichment of recalcitrant macromolecular organic matter onto the catalyst surface. Furthermore, the porous structure enhances the effective exposure of catalytic active sites, and the magnetic properties facilitate backwashing and electromagnetic recovery, thus balancing reaction efficiency with ease of maintenance. The intrinsically present Co and Ni metal oxides in the ash, while retained in the catalyst, can also act as co-catalytic elements to promote Fe... 3+ / Fe 2+The redox cycle on the catalyst surface enhances the continuous generation of ·OH free radicals and delays catalyst deactivation;

[0029] 6. The heterogeneous catalytic system of this invention achieves Fe on the catalyst surface. 3+ / Fe 2+ The surface circulation reacts with hydrogen peroxide to efficiently generate hydroxyl radicals (·OH) to break the carbon-carbon and carbon-oxygen bonds of organic matter, degrading it into small molecule products and improving its biodegradability; the chloride ions present in the ash can also promote the reaction rate of Fe3O4 and H2O2 at a certain concentration, enhancing the generation of ·OH, thus making this process more adaptable to high-chlorine environments. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings and their markings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the fixed-bed Fenton reactor described in the embodiments of this utility model specification;

[0032] Figure 2 This is a schematic diagram of the nozzle arrangement as described in the embodiments of this utility model specification.

[0033] The meanings of the symbols marked in the figure are as follows:

[0034] 1—Shell;

[0035] 10—Inlet mixing zone; 11—Pipe mixer; 12—Nozzle;

[0036] 20—Catalyst packing zone;

[0037] 30—Water outlet area, 31—Water outlet weir, 32—Annular water outlet trough, 33—Gas collection hood;

[0038] 41—Backwash water pump, 42—Backwash water outlet tank. Detailed Implementation

[0039] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the specific implementation methods of this utility model will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of this utility model. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0040] To keep the drawings concise, each figure only schematically shows the parts relevant to the utility model, and these do not represent the actual structure of the product. Furthermore, for ease of understanding, in some figures, only one of the components with the same structure or function is schematically depicted, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one."

[0041] It should also be further understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0042] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0043] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0044] According to one embodiment of the present invention, a fixed-bed Fenton reaction apparatus is provided, such as... Figure 1 The reaction device is a sealed vertical cylindrical shell. From bottom to top, the shell 1 is arranged a water inlet mixing zone 10, a catalyst packing zone 20, and a water outlet zone 30. Before entering the device via the inlet water pipeline, the COD signal of the inlet water is detected by an online COD monitoring component. The inlet water pipeline is connected to the H2O2 dosing branch via a pipe mixer 11. The pipe mixer 11 is used to rapidly premix the H2O2, which is added according to the inlet water COD, with the inlet water. The outlet of the pipe mixer 11 is connected to a ring distribution pipe, which evenly distributes the mixture to several nozzles 12. Figure 2 The nozzle 12 is arranged tangentially and obliquely relative to the inner wall of the shell. In this embodiment, the combination of the annular distribution pipe and the tangential nozzle causes the mixed liquid to act on the inner wall of the shell in a tangential and oblique (preferably 30-45°) spray manner, forming a circumferential swirling flow field. The swirling flow field, in conjunction with the downstream water distribution baffle, can evenly distribute the mixed liquid and reduce the inlet short circuit, significantly improving the contact efficiency and mass transfer rate between H2O2 and the aqueous phase, thereby increasing the unit volume processing intensity.

[0045] In the specific design, the number of nozzles 12 can be selected as 2, 4, or 8, arranged at equal intervals along the circumference and staggered in phase to improve the uniformity of the circumferential distribution. The nozzles 12 are connected to the annular distribution pipe using standard flanges or detachable threaded joints with sealing gaskets for easy on-site replacement and maintenance. A check valve is preferably installed between the annular distribution pipe and the pipeline mixer 11 to prevent backwash water from flowing back to the pipeline mixer 11 during backwashing, protecting the pipeline mixer 11 from liquid backflow and contamination. This mass transfer and maintenance design balances operational efficiency and process robustness.

[0046] The catalyst packing zone 20 is located in the middle, with the catalyst layer supported by a water distribution baffle. The catalyst consists of porous magnetic particles (3-5 mm in diameter), and the filling rate is controlled at 50%-70% of the total volume of the device. The arrangement and aperture design of the water distribution baffle are used to ensure that the swirling water from the nozzle 12 is evenly distributed before entering the catalyst layer, avoiding local erosion and suppressing channeling and blockage, thus ensuring the geometric utilization rate of the catalyst layer. A gas collecting component, preferably an inverted trumpet-shaped gas collecting hood 33, is arranged above the catalyst packing zone 20 along the axis of the shell 1. The gas collecting hood 33 is connected to the external waste gas treatment system through a waste gas discharge port.

[0047] In a specific embodiment, the heterogeneous Fenton catalyst is prepared using the following process:

[0048] High-iron ash slag was selected, mainly composed of 50-70 wt% iron oxides, and also containing 20-25 wt% MoO3, 6-12 wt% NiO, 2-8 wt% SiO2, 1-5 wt% CoO, and 1-2 wt% Al2O3. This high-iron ash slag was crushed and sieved to 50-80 mesh to obtain uniformly sized raw material powder, which was used as the base material. Subsequently, the ash slag was mixed with chopped agricultural waste biomass (e.g., rice husks) in a suitable ratio, and then placed in a reduction furnace for heating under a reducing atmosphere to reduce the Fe content in the ash slag. 3+ The material is reduced and transforms into a magnetic Fe3O4 phase within the temperature range of 300–700℃. After reduction, the magnetic components are enriched by magnetic separation using a strong magnetic field to enrich Fe3O4 and its associated metallic components such as Co and Ni. The magnetically separated material is washed three times alternately with deoxygenated water and anhydrous ethanol to remove soluble impurities from the surface and to dehydrate it. The resulting magnetic powder is then mixed with inorganic binders such as silica sol (or pseudoboehmite) and granulated. The resulting wet granules are dried at 100–120℃ for 4–8 hours and finally calcined at 800–1000℃ for 20–60 minutes to obtain a densified granular catalyst that retains its porous structure.

[0049] The obtained catalyst consists of porous magnetic particles with a particle size controlled to 3–5 mm through granulation, and a specific surface area of ​​approximately 200–300 m². 2The catalyst exhibits a porosity of approximately 70-80% and good magnetic responsiveness, facilitating rapid recovery using electromagnetic devices during shutdown or maintenance. In fixed-bed packing applications, the catalyst in this embodiment demonstrates strong surface adsorption capacity, unobstructed mass transfer channels, and abundant surface Fe... 3+ / Fe 2+ It is easy to recycle and is suitable for use in the fixed-bed Fenton system of this invention.

[0050] In this embodiment, the effluent zone 30 is a combination of an annular effluent channel 32 and an effluent weir 31: the annular effluent channel 32 is fixed around the inner wall of the shell, and an effluent weir 31 (preferably a triangular weir or a trapezoidal weir) is provided on the inner side. The effluent is discharged from the effluent channel through the outlet or, if it does not meet the standards, returned to the inlet end for further treatment through the return pipeline. The effluent zone 30 is also equipped with online monitoring components for effluent pH and ORP, as well as online monitoring components for effluent COD. The monitoring signals are used to form an interlock control with the actuators (effluent valve, dosing pump, etc.) to ensure that the effluent consistently meets the standards.

[0051] To ensure long-term continuous operation and facilitate maintenance, the device is equipped with a backwash circuit using effluent as the water source. Effluent is pumped by backwash water pump 41 and flows upwards through the catalyst layer via the backwash water inlet at the bottom of the shell 1 for backwashing. The backwashed wastewater is collected in the backwash water outlet tank 42, located below the effluent zone 30 and fixed to the inner wall of the shell, and discharged through the backwash water discharge port. The inner bottom edge of the backwash water outlet tank 42 is preferably inclined towards the center of the shell 1 to facilitate the convergence of backwash liquid and, in conjunction with the gas collection hood 33, guide the released gas to the collection port of the gas collection hood 33. The backwash process design allows for the restoration of the catalyst layer's permeability without disassembling the catalyst layer. The preferred backwash cycle is 3–4 months, and the backwash intensity is 10–15 L / m. 2 • The backwashing time is 15-20 minutes; and it is advisable to connect multiple units in parallel within the plant area so that other units can maintain the continuous processing capacity of the system when a single unit is backwashed or under maintenance. This parallel redundancy improves the availability of the project and the continuity of processing.

[0052] In terms of control and electrical connections, the device is equipped with an automatic control unit. This control unit is electrically connected to online monitoring components for influent COD, influent pH, effluent COD, effluent pH, and ORP. It is also electrically connected to actuators such as the H2O2 and acid (HCl) dosing pumps, the effluent valve, the backwash water pump 41, and the electromagnetic recovery device. This achieves interlocking between influent COD and H2O2 dosing, influent pH and acid dosing, and effluent COD and the effluent valve, thereby reducing reagent waste and the frequency of manual intervention while ensuring treatment effectiveness. For ease of maintenance and catalyst replacement, the device can be equipped with an upper or side-mounted electromagnetic recovery device, which uses magnetic force to quickly extract magnetic particles during shutdown or maintenance, facilitating offline regeneration or replacement.

[0053] The advantages of the structure and connection relationship in this embodiment are as follows: ① The tangential tilting nozzle-swirl-water distribution baffle system significantly improves the contact and mass transfer efficiency between H2O2 and wastewater, reduces chemical consumption, and shortens the treatment volume; ② The porous magnetic particle catalyst and the backwash circuit work together to achieve low-iron sludge and easy-to-maintain long-term operation; ③ The gas collection hood 33 and the backwash geometry work together to reduce VOCs emissions and facilitate centralized treatment; ④ Online monitoring and interlocking control improve automation and economy, and the whole system has good feasibility and maintainability in engineering.

[0054] According to another embodiment of this utility model, a fixed-bed Fenton pretreatment method is provided. Using the reaction device of the above embodiment as the operating object, before startup, the granular catalyst prepared in the aforementioned embodiment is filled into the catalyst packing zone 20 according to the design, with the filling rate adjusted to 50%–70% (preferably 60%) of the total volume of the device. The connection and sealing between the annular distribution pipe and each nozzle are checked. It is confirmed that the check valve, backwash water pump 41, outlet valve, dosing pump, and online monitoring components (influent COD, influent pH, effluent COD, effluent pH, effluent ORP) and control unit are electrically connected well. It is also confirmed that the gas collection hood 33 is connected to the waste gas treatment system, and that the backwash water outlet tank 42 and discharge pipeline are unobstructed.

[0055] After the system is airlifted and purged to pass the airtightness test, the inlet water pipeline is opened to supply water. The inlet water's COD value is measured in real time by the inlet water COD online monitoring component. The control unit starts and adjusts the H2O2 dosing pump according to the inlet water COD signal at a preset ratio (preferably 1.0 to 1.5 times) to ensure that hydrogen peroxide is fully mixed with the inlet water at the pipeline mixer 11. The mixture is tangentially sprayed into the inlet water mixing zone 10 through the annular distribution pipe and nozzle 12, forming a swirling flow. After the swirling flow stabilizes at the water distribution baffle, it enters the catalyst packing zone 20 evenly, allowing the organic matter to undergo the following redox cycle reaction process on the catalyst surface:

[0056] Fe 2+ +H₂O₂→Fe 3+ +·OH+OH -

[0057] Fe 3+ +H₂O₂→Fe 2+ +·OOH+H +

[0058] Fe 3+ +·OOH→Fe 2+ +O2+H +

[0059] On the inlet side, the addition of acid (HCl) is controlled by online monitoring of the inlet pH to adjust and maintain the inlet pH within the target range of 5-7, thus balancing catalytic activity and alkali consumption. The effluent overflows from the annular effluent trough 32 to the effluent weir 31 and is monitored online for effluent COD to determine whether the effluent meets the standards. If it does not meet the standards, it is automatically returned to the inlet end for retreatment via an automatic valve. Volatile components or gases generated during the reaction are collected by the gas collection hood 33 and sent to the waste gas treatment system for treatment. The operating parameters (H2O2 dosage, inlet / outlet pH, effluent ORP) are recorded by the control unit and automatically fine-tuned according to preset thresholds to ensure that the effluent ORP is preferably in the range of 200-300mV to maintain reaction activity.

[0060] In the specific design, the hydrogen peroxide dosage is controlled at 1 to 1.5 times the influent COD, the catalyst contact time is controlled at 30 to 60 minutes, the total residence time (including mixing and catalyst packing zone) is controlled at 1 to 2 hours, the influent pH is 5 to 7, and the effluent pH is maintained at 6 to 8. This combination of parameters, when used in conjunction with the device described in the previous embodiment, can maintain a high COD removal efficiency even under high-salt, high-Cl- wastewater conditions. Compared to traditional homogeneous Fenton reactors, it reduces reagent consumption and eliminates the need for subsequent iron sludge flocculation and sedimentation treatment, thereby saving operating costs and reducing secondary pollution.

[0061] To maintain the permeability and activity of the catalyst bed, the backwashing cycle is set to once every 3 to 4 months based on operational experience. The backwashing process involves stopping the water inlet, starting the backwash water pump 41 to allow the effluent to pass through the catalyst bed from bottom to top and be discharged from the backwash water outlet tank 42. The preferred backwashing intensity is 10 to 15 L / m. 2 The backwashing time is preferably 15–20 minutes. During backwashing, a check valve and control logic prevent backwash water from flowing back to the pipeline mixer 11. After backwashing, the incoming water is restored and processed by other parallel devices to ensure system continuity. If the catalyst permeability or activity does not recover to the specified standard after backwashing, the catalyst is removed for offline regeneration or replacement using the device's electromagnetic recovery mechanism.

[0062] This embodiment achieves efficient pretreatment of high-salt / high-chlorine wastewater under near-neutral pH conditions through structural optimization of the reaction device (geometric coordination of nozzle swirl, water distribution baffle, gas collection hood 33 and backwash outlet tank) and the material advantages of particulate catalyst (ash resource utilization, magnetic particles, endogenous co-catalytic substances). Operating costs and secondary pollution are significantly reduced, and the backwash and parallel redundancy mechanism ensures long-term continuous operation and easy maintenance.

[0063] To provide a clearer understanding of the technical solution and effects of this utility model, the following examples are given, including comparative examples 1-3 and embodiments 1-6.

[0064] Comparative Example 1

[0065] Wastewater from a chemical industrial park, discharged by enterprises including coal chemical and fine chemical companies, has a high COD concentration (8000 mg / L) and a high content of recalcitrant organic matter, with a B / C ratio of approximately 0.12 and Cl... - The concentration was as high as 3000 mg / L. Using a conventional Fenton process, the H2O2 dosage was 5000 mg / L, and HCl was added to adjust the reaction pH to 3-4. The reaction time was 30 minutes. After the reaction, the effluent COD decreased to 4640 mg / L, with a COD removal rate of 42%, and the B / C ratio increased to 0.33. Iron sludge production was 10 g / L. After one month of operation, the COD removal rate decreased to 30%. The Cl in the wastewater... - It will reduce the effectiveness of the Fenton reaction.

[0066] Example 1

[0067] Wastewater from a chemical industrial park, discharged by enterprises including coal chemical and fine chemical companies, has a high COD concentration (8000 mg / L), a high content of recalcitrant organic matter (B / C ratio of approximately 0.12), and a high salt content (TDS of 12000 mg / L). Using this patented fixed-bed Fenton process, with an H2O2 dosage of 4000 mg / L, the reaction pH only needs to be adjusted to 5-6, and the reaction time is 30 minutes. After the reaction, the effluent COD decreased to 3360 mg / L, achieving a COD removal rate of 58%, and the B / C ratio increased to 0.38. No iron sludge was generated. After one month of operation, the COD removal rate reached 60%, and the Cl in the wastewater... - It can accelerate the formation of hydroxyl groups, thereby enhancing the catalytic reaction.

[0068] Example 2

[0069] Wastewater from a chemical industrial park, discharged by enterprises including coal chemical and fine chemical companies, has a high COD concentration (8000 mg / L), a high content of recalcitrant organic matter (B / C ratio of approximately 0.12), and a high salt content (TDS of 12000 mg / L). This patented fixed-bed Fenton process was used for treatment, with an H2O2 dosage of 4000 mg / L, a reaction pH adjusted to 5-6, and a reaction time of 60 minutes. After the reaction, the effluent COD decreased to 2920 mg / L, achieving a COD removal rate of 63.5%, and the B / C ratio increased to 0.42. No iron sludge was generated.

[0070] Comparative Example 2

[0071] Wastewater from a chemical industrial park, discharged by enterprises including coal chemical and fine chemical companies, has a high COD concentration (8000 mg / L), a high content of recalcitrant organic matter (B / C ratio of approximately 0.12), and a high salt content (TDS of 12000 mg / L). This patented fixed-bed Fenton reactor was used, but commercially available catalyst was used. The H2O2 dosage was 4000 mg / L, the reaction pH was 5-6, and the reaction time was 30 minutes. After the reaction, the effluent COD decreased to 4320 mg / L, the COD removal rate was 46%, and the B / C ratio increased to 0.35.

[0072] The treatment effect of commercially available catalysts is worse than that of the catalyst in this patent.

[0073] Comparative Example 3

[0074] A dyeing and printing wastewater from a certain enterprise has a COD concentration of 8610 mg / L and a B / C ratio of approximately 0.15, making it difficult to directly biodegrade and requiring pretreatment. A conventional Fenton process was used, with the reaction pH adjusted to around 3 and the catalyst contact time extended to 30 minutes. After the reaction, the effluent COD decreased to 4380 mg / L, achieving a COD removal rate of 49%, and the B / C ratio increased to 0.38. The effluent then enters a neutralization tank, where liquid alkali is added to adjust the pH to neutral. The wastewater from the neutralization tank flows by gravity to a degassing tank, where agitation is achieved by blower to remove any remaining air bubbles. The effluent from the degassing tank flows by gravity to a coagulation reaction tank, where PAM flocculant is added and allowed to react fully, causing the iron sludge in the wastewater to flocculate. The coagulated wastewater then flows by gravity to a sedimentation tank to settle the iron sludge. The iron sludge is then pumped to the original sludge treatment system for further treatment, and the supernatant enters the subsequent AO biological treatment unit.

[0075] Example 3

[0076] A dyeing and printing wastewater from a certain enterprise had a COD concentration of 8610 mg / L and a B / C ratio of approximately 0.15, making it difficult to directly biodegrade and requiring pretreatment. This patented fixed-bed Fenton process was used for treatment. The reaction pH was adjusted to 5-6, and the catalyst contact time was 30 minutes. After the reaction, the effluent COD decreased to 3013 mg / L, achieving a COD removal rate of 65%, and the B / C ratio increased to 0.44. The pH of the pretreated effluent was then adjusted back to 7-8 before continuing into the subsequent AO biological treatment unit. No iron sludge was generated, and degassing was unnecessary.

[0077] Compared with the conventional Fenton process, the fixed-bed Fenton process of this patent can greatly reduce the amount of acid and alkali required for pH adjustment, save on iron sludge treatment costs, and collect waste gas through gas-liquid separation in one reactor, thus greatly shortening the process flow.

[0078] Example 4

[0079] In the reactor described in Example 3 above, after three months of operation, backwashing was performed at an intensity of 12 L / m²·s for 15 minutes. The backwash water was discharged into the backwash water tank. After backwashing, water was re-introduced, and the COD removal efficiency was essentially unaffected.

[0080] Example 5

[0081] In the reactor of Example 3 above, after running for a period of time, due to the low-load operation of the process unit, the COD concentration of the wastewater decreased to 6000 mg / L, and the COD of the reactor effluent was 1800 mg / L, with a COD removal rate of 70%. Low-load operation is beneficial to COD removal.

[0082] Example 6

[0083] In the reactor described in Example 3 above, the catalyst inside the device needs to be completely removed during major maintenance. This can be done by using an electromagnet to remove the magnetic catalyst, which is simple to operate and can be automated.

[0084] The above-described embodiments are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the appended claims.

Claims

1. A fixed bed Fenton-like reaction device, characterized by, It includes a sealed shell, inside which, from bottom to top, are formed an inlet mixing zone, a catalyst packing zone, and an outlet zone; The water inlet mixing zone is connected to the water inlet pipeline, which is connected to the H2O2 dosing branch via a pipeline mixer. The outlet of the pipeline mixer is connected to multiple nozzles arranged tangentially and obliquely relative to the inner wall of the shell via a distribution pipe to form a swirling flow in the water inlet mixing zone. The catalyst packing region supports a heterogeneous Fenton-like catalyst. The water outlet area is equipped with an annular water outlet trough and is connected to the water outlet pipeline; A gas collection component is installed above the catalyst packing area and connected to an external waste gas treatment system via a waste gas emission outlet; The reaction device is also equipped with a backwash circuit with effluent as the water source. The backwash circuit includes a backwash water pump connected to the annular effluent tank, a backwash water inlet located at the bottom of the shell, and a backwash water outlet tank located in the effluent area, below the annular effluent tank and fixed to the inner wall of the shell. The bottom edge of the backwash water outlet tank is inclined to the center of the shell, and works with the gas collecting component to guide the rising gas during the reaction to the gas collecting component and discharge it through the exhaust port.

2. The fixed bed Fenton-like reaction device according to claim 1, characterized in that, The nozzles are arranged at equal intervals along the circumference of the shell and staggered in phase, and the spray direction of the nozzles makes an angle of 30 to 45° with the tangential direction of the inner wall of the shell.

3. The fixed bed Fenton-like reaction device according to claim 1, characterized in that, The catalyst packing zone is supported by a water distribution baffle, and the catalyst filling rate is 50-70% of the total volume of the reaction device.

4. The fixed-bed Fenton-like reaction device according to claim 1, characterized in that, An outlet weir is provided on the inner side of the annular outlet channel. The outlet weir is a triangular weir or a trapezoidal weir.

5. The fixed-bed Fenton-like reaction device according to claim 1, characterized in that, The gas collecting component is an inverted trumpet-shaped gas collecting hood, located on the shell axis above the catalyst packing area.

6. The fixed-bed Fenton-like reaction device according to claim 1, characterized in that, An acid dosing port and an online pH monitoring unit for the influent are installed on the side of the influent mixing zone, connected to this zone; an online COD monitoring unit for the influent is installed on the influent pipeline; online pH and ORP monitoring units for the effluent are installed in the effluent zone, and an online COD monitoring unit for the effluent is installed on the effluent pipeline; and... The aforementioned online monitoring components are electrically connected to their respective actuators to form interlocking controls, including: influent COD and H2O2 dosing interlock, influent pH and acid dosing interlock, and effluent COD and effluent valve interlock.

7. The fixed-bed Fenton-like reaction device according to claim 1, characterized in that, The backwash circuit flows through the catalyst packing area from bottom to top, and the backwash water is collected in the backwash water outlet tank and discharged from the backwash water discharge port.

8. The fixed-bed Fenton-like reaction device according to claim 1, characterized in that, The heterogeneous Fenton catalyst is a magnetic particle catalyst with a particle size of 3-5 mm. It has a porous structure and is suitable for backwashing and recovery.

9. The fixed-bed Fenton-like reaction device according to claim 8, characterized in that, The magnetic particle catalyst is prepared by sequentially reducing, magnetically separating, mixing with an inorganic binder, and calcining high-iron ash slag.

10. The fixed-bed Fenton-like reaction device according to claim 1, characterized in that, Multiple reaction units are connected in parallel so that the remaining reaction units can maintain continuous water intake of the system when any one unit is backwashed or shut down for maintenance.

Images