Three-phase catalytic oxidation coupling reaction device for industrial wastewater treatment

Abstract

The utility model discloses a three -phase catalytic oxidation coupling reaction device for industrial wastewater treatment, including jar body, the inside of jar body is equipped with the flow guide wall, and the flow guide wall divides the inside of jar body into catalytic pre -reduction unit and catalytic oxidation unit, is equipped with water distribution system at the bottom of catalytic pre -reduction unit one side, is equipped with catalyst frame above water distribution system, and the inside of catalyst frame is used for filling reduction type catalyst module, is equipped with microporous titanium plate gas distribution system at the bottom of catalytic oxidation unit one side, is equipped with catalytic carrier area above microporous titanium plate gas distribution system, and the inside of catalytic carrier area is used for filling catalytic particle, is equipped with oxidant adding pipe and catalyst adding pipe at the top of catalytic oxidation unit, still is equipped with magnetization system outside catalytic oxidation unit. The utility model constructs a " catalytic pre -reduction - catalytic oxidation " series reaction system, and through the device structural coupling, forces wastewater to experience efficient reduction activation and depth oxidation two processes in turn, realizes the synergic degradation to PFCs in wastewater.

Description

Technical Field

[0001] This utility model belongs to the field of industrial wastewater deep treatment technology, specifically relating to a three-phase catalytic oxidation coupled reaction device for industrial wastewater treatment, which is particularly suitable for removing recalcitrant perfluorinated compounds (PFCs) from wastewater from dyeing, printing and dyeing, chemical and other industries. Background Technology

[0002] Perfluorinated compounds (PFCs) are recognized as persistent organic pollutants that are difficult to degrade due to their strong CF bonds, exhibiting high chemical stability and biological inertness. Traditional Fenton oxidation technology and its improved versions (such as fluidized bed Fenton oxidation) have good removal effects on conventional pollutants (COD, color, total phosphorus) when treating industrial dyeing wastewater. However, they have limited degradation efficiency for residual perfluorinated compounds (PFCs) in water, especially short-chain PFCs (such as PFBA, PFPeA), with low removal efficiency (usually <50%). Furthermore, they suffer from problems such as large reagent dosage, high sludge production, and high operating costs.

[0003] The reason for this is that traditional technologies mainly rely on the oxidation of hydroxyl radicals (·OH), but the kinetic rate of ·OH breaking the high-energy CF bonds in PFC molecules is extremely slow. Existing research has found that through a synergistic pathway of "catalytic pre-reduction-catalytic oxidation," the CF bonds of PFCs can be broken first through a reduction reaction to generate an intermediate that is more easily oxidized, and then complete mineralization can be achieved through an oxidation reaction. However, there is currently a lack of dedicated reaction equipment on the market that can effectively realize this synergistic process, hence this application. Utility Model Content

[0004] To address the aforementioned issues, this invention provides a three-phase catalytic oxidation coupled reaction device for industrial wastewater treatment, achieving the dual process requirements of efficient reduction and activation and deep oxidation of wastewater, thereby realizing the synergistic degradation of PFCs in the wastewater.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is as follows: A three-phase catalytic oxidation coupled reaction device for industrial wastewater treatment includes a tank with a flow guide wall inside, dividing the tank into a catalytic pre-reduction unit and a catalytic oxidation unit. A water distribution system is located at the bottom of one side of the tank corresponding to the catalytic pre-reduction unit, and a catalyst frame is located above the water distribution system, with a reducing catalyst module detachably installed within the catalyst frame. A microporous titanium plate gas distribution system is located at the bottom of one side of the tank corresponding to the catalytic oxidation unit, with a catalyst support zone above it. The catalyst support zone is filled with catalyst particles and together with the microporous titanium plate gas distribution system, forms a fluidized bed reaction zone. A reagent dosing system is located at the top of one side of the tank corresponding to the catalytic oxidation unit, including an oxidant dosing pipe and a catalyst dosing pipe. A magnetization system is also located on the outer side of one side of the tank corresponding to the catalytic oxidation unit.

[0006] Furthermore, the water distribution system is connected to a corresponding water inlet, and an outlet is provided on the upper part of one side of the tank corresponding to the catalytic oxidation unit.

[0007] Furthermore, a sludge discharge port is provided at the bottom of the tank. The sludge discharge port is connected to a pipeline that is divided into two branches. One branch is connected to the water distribution system after passing through the sludge return pump; the other branch is connected to the sludge thickening tank.

[0008] Furthermore, the water distribution system is uniformly provided with water outlet holes, with a hole diameter of 10-12mm and a hole spacing of 150-200mm.

[0009] Furthermore, the pore size of the microporous titanium plate air distribution system is 5-10 μm.

[0010] Furthermore, there are multiple catalyst frames, which are arranged sequentially and at intervals above the water distribution system. Furthermore, the height of the water outlet is set lower than the height of the guide wall.

[0011] Furthermore, the catalytic oxidation unit is provided with a three-phase separation zone above the catalytic support zone for separating gaseous, liquid and solid catalytic particles in the water flow.

[0012] This invention constructs a tandem reaction system of "catalytic pre-reduction-catalytic oxidation." Through the structural coupling of the device, wastewater is forced to undergo two processes sequentially: efficient reduction activation and deep oxidation, thereby achieving the synergistic degradation of PFCs in the wastewater. This invention achieves highly efficient synergistic removal of PFCs, ensures stable compliance with conventional pollutant standards, and significantly reduces wastewater treatment operating costs. Furthermore, this invention exhibits good adaptability to influent water quality and provides stable effluent quality. Attached Figure Description

[0013] Figure 1This is a schematic diagram of the three-phase catalytic oxidation coupled reaction device for industrial wastewater treatment according to the present invention; In the diagram: 1. Tank; 2. Baffle wall; 3. Catalytic pre-reduction unit; 4. Catalytic oxidation unit; 5. Water distribution system; 6. Catalyst frame; 7. Microporous titanium plate gas distribution system; 8. Catalytic carrier zone; 9. Oxidant dosing pipe; 10. Catalyst dosing pipe; 11. Magnetization system; 12. Inlet; 13. Outlet; 14. Sludge return pump; 15. Sludge thickening tank; 16. Three-phase separation zone. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be described in detail below. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0015] like Figure 1 As shown, the core of the technical solution in this embodiment lies in constructing a series reaction system of "catalytic pre-reduction-catalytic oxidation". Through the structural coupling of the device, the wastewater is forced to undergo two processes of efficient reduction activation and deep oxidation in sequence, thereby achieving the synergistic degradation of PFCs.

[0016] ① Overall structure of the device In this embodiment, the device is a one-piece rectangular reinforced concrete structure or a corrosion-resistant carbon steel tank 1 with an open top and an effective volume of 60m³. 3 The designed processing capacity is 1000 tons / day. The tank 1 is internally divided into two functional units by a guide wall 2: a catalytic pre-reduction unit 3 and a catalytic oxidation unit 4. The wastewater treatment process is as follows: influent → catalytic pre-reduction unit 3 → through guide wall 2 → catalytic oxidation unit 4 → effluent.

[0017] ② Catalytic pre-reduction unit 3 (specific structure and operation) Function: To reduce and defluorinate PFCs, destroying their "fluorine shell" structure and generating intermediates that are more easily oxidized.

[0018] Specific structure: A UPVC perforated pipe water distribution system 5 is laid at the bottom of the unit. The water distribution system 5 has evenly distributed outlet holes with a diameter of 10 mm and a spacing of 200 mm to ensure uniform wastewater flow and prevent short-circuiting. The water distribution system 5 is connected to corresponding inlets 12. Above the water distribution system 5 are four retractable catalyst frames 6. The catalyst frames 6 are neatly filled with honeycomb-shaped sintered metal reducing catalyst modules (catalyst frame 6 dimensions: 1000mm × 1000mm × 1000mm). The retractability of the catalyst frames 6 is achieved by setting corresponding guide rails on the tank body 1 and the guide wall 2, facilitating the feeding of the reducing catalyst modules. The composition and preparation of the reducing catalyst modules are as follows: This module is prepared using a metal powder sintering method, specifically a Pd / Fe / S composite catalyst, where the Pd loading is 0.5 wt% and the molar ratio of Fe to S is 1:0.1. This composition has been verified in the project to have the highest reduction and defluorination efficiency for PFCs.

[0019] Operating conditions: The hydraulic retention time (HRT) of wastewater in this unit is controlled at 30-45 minutes. No additional reducing agents are required; the electrons required for the reaction are provided by the catalyst itself and some organic matter in the water.

[0020] ③ Catalytic oxidation unit (specific structure and operation) Function: Deeply oxidizes reduced and activated PFC intermediates and other organic matter to achieve mineralization.

[0021] Structure: The main body of this unit is designed as an internal circulating fluidized bed. A microporous titanium plate gas distribution system 7 with a pore size of 5-10 μm is located at the bottom. Above the microporous titanium plate gas distribution system 7 is a catalyst support zone 8, which is filled with catalyst particles. In this embodiment, the catalyst support zone 8 is filled with porous diatomaceous earth particles (particle size 1-3 mm, bulk density 0.8-1.0 g / cm³) with surface-loaded iron oxide. 3 The iron-based composite catalyst particles fill 30% of the reaction zone volume. The reagent dosing system includes an oxidant dosing pipe 9 and a catalyst dosing pipe 10, which can be installed at the upper end of the tank 1 via a suspension support mechanism such as a suspension rod. The oxidant dosing pipe 9 is located above the microporous titanium plate gas distribution system 7, continuously adding 30% concentration hydrogen peroxide (H2O2), with the dosing amount to the influent COD mass ratio approximately 1:1.5 - 1:2. The catalyst dosing pipe 10 is located near the oxidant dosing pipe 9, continuously adding 10% concentration ferrous sulfate (FeSO4) solution to maintain the Fe content in the reaction system. 2+The concentration is 50-100 mg / L; Magnetization system 11: A solenoid-type electromagnetic coil (magnetizer) is wound around the outer wall of the catalytic oxidation unit 4. During operation, a direct current of 1-3 A is applied to generate a stable magnetic field of 50-150 mT inside the reactor. This magnetic field can enhance the catalytic activity of the iron-based catalyst, promote the generation of ·OH, and prevent excessive deposition of iron sludge; A water outlet 13 is provided on the upper part of one side of the tank 1 corresponding to the catalytic oxidation unit 4. Above the catalyst carrier zone 8 is the three-phase separation zone 16: An enlarged settling zone is designed at the top of the unit to achieve gas, liquid, and solid three-phase separation.

[0022] The three-phase separation zone 16 is a physical partition within the reactor. Its core function is to efficiently and rapidly separate the rising fluid mixture (gas, liquid, and solid) using the principle of gravity sedimentation. This achieves the following: gas escapes from the top; solid (catalyst) settles and returns to the reaction zone; and clarified liquid overflows from the side as effluent. The gas phase mainly consists of unreacted air / N2 (blown in), carbon dioxide generated from the reaction, and other possible trace gases. The liquid phase mainly consists of water after catalytic oxidation treatment, containing dissolved small organic molecules and inorganic salts (such as F- ions). The solid phase mainly consists of iron-based composite catalyst particles, and possibly small amounts of microbial flocs and aged, detached catalyst coatings.

[0023] The three-phase separation region 16 has the following functions: (1) Retaining the catalyst (core function): Preventing the loss of expensive iron-based catalyst particles with the effluent and maintaining a sufficient catalyst concentration in the reaction zone is a prerequisite for the stable operation of the reactor.

[0024] (2) Ensure the quality of the effluent: Separate suspended solid particles to ensure that the effluent is clear and meets the discharge indicators such as suspended solids (SS).

[0025] (3) Release reaction gases: The carbon dioxide (CO2) produced by the reaction and the unreacted air are discharged from the system in a timely manner to avoid the accumulation of gases in the system, which would affect the water flow and reaction efficiency.

[0026] (4) Maintaining system balance: Achieving dynamic balance between reaction (disturbance) and separation (sedimentation) within the same reactor is the key to the success of fluidized bed technology.

[0027] The three-phase separation zone 16 is located at the top of the catalytic oxidation unit 4; specifically, its bottom boundary is the highest expansion interface that the fluidized bed catalytic particles can reach during normal operation, and its top boundary is the height of the outlet position.

[0028] ④ Sludge return and separation system A sludge discharge port is set at the bottom of the catalytic oxidation unit 4. The sludge discharge port connecting pipeline is divided into two branches. One branch is connected to the water distribution system 5 through the sludge return pump 14; the other branch is connected to the sludge thickening tank 15.

[0029] Approximately 30%-50% of the catalyst-containing sludge is returned to the inlet of the catalytic pre-reduction unit 3 via sludge return pump 14. This serves two purposes: firstly, it utilizes the undeactivated catalyst components in the sludge to enhance the reduction effect; secondly, it acts as crystal nuclei, promoting the co-precipitation of any precipitates that may form in the catalytic pre-reduction unit 3, thus achieving iron recycling and sludge reduction. The remaining sludge is discharged into the sludge thickening tank 15 for further treatment.

[0030] The core of this invention lies in achieving, for the first time, a highly efficient synergistic degradation pathway of recalcitrant perfluorinated compounds (PFCs) through "catalytic pre-reduction-catalytic oxidation" within a single device via a specific physical structure and construction. The core protection is not the chemical reaction principle itself, but the engineering device entity that realizes this synergistic reaction. Its main core technical points are: an integrated structure in which the catalytic pre-reduction unit 3 and the catalytic oxidation unit 4 are directly connected in series in physical space; a detachable, porous, metal powder-based reducing catalyst module is installed inside the catalytic pre-reduction unit 3; a magnetization system 11 is integrated on the outer wall or inside the catalytic oxidation unit (preferably a fluidized bed structure); a sludge return system is provided to return a portion of the catalyst-containing sludge from the bottom of the catalytic oxidation unit 4 to the inlet of the catalytic pre-reduction unit 3; the catalytic pre-reduction unit 3 and the catalytic oxidation unit 4 are integrated into a single tank 1, separated by a guide wall 2.

[0031] The coupled reaction device for three-phase catalytic oxidation of industrial wastewater proposed in this utility model, through the specific device structure design and operating conditions described above, achieves the following quantifiable technical effects (based on pilot-scale project data) in the treatment of specific industrial wastewater: The following technical effects are achieved: (1) Highly efficient synergistic removal of PFCs: The total removal rate of multiple PFCs (such as PFOA, PFOS, PFNA, etc.) in wastewater is increased from less than 50% by traditional Fenton to 80%-95%. In particular, the removal rate of long-chain PFCs can reach 93.64%.

[0032] (2) Conventional pollutants are stably met: the CODcr of the effluent can be stably controlled below 50 mg / L, and the color, total phosphorus and other indicators simultaneously meet the Class A standard of the "Discharge Standard of Pollutants for Urban Wastewater Treatment Plants" (GB 18918-2002).

[0033] (3) Significantly reduced operating costs: Due to the reduction and activation step improving the efficiency of subsequent oxidation, the consumption of hydrogen peroxide is reduced by about 20%-30% compared with the traditional Fenton process, and the production of iron sludge is reduced by about 15%-25%, making the overall operating cost more economical.

[0034] (4) Strong resistance to shock loads: The modular catalyst and fluidized bed design enable the system to adapt well to fluctuations in influent water quality (such as COD changes in the range of 150-200 mg / L) and ensure stable effluent water quality.

[0035] It should be noted that the catalysts and their preparation processes mentioned in this application are all existing conventional technologies, and will not be described in detail here.

[0036] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.

Claims

1. A three-phase catalytic oxidation coupled reaction device for industrial wastewater treatment, characterized in that, The tank (1) includes a flow guide wall (2) inside the tank (1), which divides the interior of the tank (1) into a catalytic pre-reduction unit (3) and a catalytic oxidation unit (4). A water distribution system (5) is provided at the bottom of one side of the tank (1) corresponding to the catalytic pre-reduction unit (3). A catalyst frame (6) is provided above the water distribution system (5). A reduction catalyst module is detachably installed inside the catalyst frame (6). A microporous titanium plate gas distribution system (7) is provided at the bottom of one side of the tank (1) corresponding to the catalytic oxidation unit (4). A catalyst carrier area (8) is provided above the microporous titanium plate gas distribution system (7). The catalyst carrier region (8) is filled with catalyst particles and together with the microporous titanium plate gas distribution system (7) forms a fluidized bed reaction zone. A reagent dosing system is provided on the top of one side of the tank (1) corresponding to the catalytic oxidation unit (4). The reagent dosing system includes an oxidant dosing pipe (9) and a catalyst dosing pipe (10). A magnetization system (11) is also provided on the outside of one side of the tank (1) corresponding to the catalytic oxidation unit (4). Furthermore, a three-phase separation zone (16) is provided above the catalyst carrier region (8) of the catalytic oxidation unit (4) to separate gas, liquid and solid catalyst particles in the water flow.

2. The three-phase catalytic oxidation coupled reaction device for industrial wastewater treatment according to claim 1, characterized in that, The water distribution system (5) is connected to a water inlet (12), and a water outlet (13) is provided on the upper part of one side of the tank (1) corresponding to the catalytic oxidation unit (4).

3. The three-phase catalytic oxidation coupled reaction device for industrial wastewater treatment according to claim 1, characterized in that, A sludge discharge port is also provided at the bottom of the tank (1). The sludge discharge port is connected to two branches. One branch is connected to the water distribution system (5) through the sludge return pump (14); the other branch is connected to the sludge thickening tank (15).

4. The three-phase catalytic oxidation coupled reaction device for industrial wastewater treatment according to claim 1, characterized in that, The water distribution system (5) is uniformly provided with water outlet holes, with a hole diameter of 10-12mm and a hole spacing of 150-200mm.

5. The three-phase catalytic oxidation coupled reaction device for industrial wastewater treatment according to claim 1, characterized in that, The pore size of the microporous titanium plate air distribution system (7) is 5-10 μm.

6. The three-phase catalytic oxidation coupled reaction device for industrial wastewater treatment according to claim 1, characterized in that, The catalyst frame (6) is multiple and is arranged sequentially at intervals above the water distribution system (5).

7. The three-phase catalytic oxidation coupled reaction device for industrial wastewater treatment according to claim 2, characterized in that, The height of the outlet (13) is set lower than the height of the guide wall (2).

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