A photochemical oxidation loop filter bed reactor and wastewater treatment system

Abstract

A photochemical oxidation circulating filter bed reactor and wastewater treatment system includes a reactor comprising a vertical cylindrical reactor shell and a water inlet located in the middle of the reactor shell. A photochemical oxidation reaction zone is formed in the reactor shell above the water inlet. An overflow port and an upper drain port are provided at the top of the photochemical oxidation reaction zone. The overflow port and the water inlet are connected by a top external circulation pipeline. A filter bed adsorption and impurity removal zone is formed in the reactor shell below the water inlet. The filter bed adsorption and impurity removal zone is provided with a multi-media filter bed. A lower drain port is provided at the bottom of the filter bed adsorption and impurity removal zone. The lower drain port is connected to the water inlet by a bottom external circulation pipeline. The present invention can significantly improve the treatment capacity of high-turbidity and difficult-to-degrade organic wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, in particular to a photochemical oxidation circulating filter bed reactor and a wastewater treatment system. Background Art

[0002] Photochemical oxidation is a chemical reaction process in which an oxidant generates hydroxyl radicals under light irradiation, which are then used to oxidize organic reactants. Depending on the mechanism of hydroxyl radical generation, photochemical oxidation can be divided into two methods: photoexcited oxidation and photocatalytic oxidation. In recent years, semiconductor heterogeneous photocatalytic oxidation has become a research hotspot in the pollutant treatment industry due to its advantages such as simplicity, no secondary pollution, mild reaction conditions, and wide applicability. It has broad development potential and application prospects. In particular, the use of TiO2 as a photocatalyst for the degradation of organic pollutants has gradually shifted from the experimental research and development stage to practical application research, but large-scale industrialization is still a long way off. One of the obstacles is the lack of high-efficiency photocatalysts and high-efficiency photocatalytic reactors that can be used continuously.

[0003] At present, there are few reports on multiphase photochemical / catalytic reactors for the purpose of practical research, among which tubular reactors have been the most studied. The catalyst in the tube can be suspended in a solution or fixed on the inner wall of the reactor, and the light source is generally placed in the center of the tube. In order to increase the utilization rate of the light source, the applicant proposed a photocatalytic fluidized bed reactor (2022108664734), in which the light source is set on the inner side of the tube wall of the lamp tube, and internal and external circulations are formed in the reactor, thereby increasing the contact stroke and time between the wastewater and the light source, and improving the catalytic efficiency. However, for high-turbidity and difficult-to-degrade organic wastewater, the transmission of ultraviolet light in the wastewater is limited, so that this technology still has certain technical difficulties in the field of treating high-turbidity and difficult-to-degrade organic wastewater by photocatalysis or photochemical oxidation. Summary of the Invention

[0004] The present invention aims to provide a photochemical oxidation circulating filter bed reactor and a wastewater treatment system, which are used to significantly improve the treatment capacity of high-turbidity and difficult-to-degrade organic wastewater.

[0005] In order to solve the above technical problems, the specific scheme adopted by the present invention is: a photochemical oxidation circulating filter bed reactor, comprising a vertical cylindrical reactor shell and a water inlet located in the middle of the reactor shell, a photochemical oxidation reaction zone is formed in the reactor shell above the water inlet, an overflow port and an upper drain port are provided at the top of the photochemical oxidation reaction zone, the overflow port and the water inlet are connected through a top external circulation pipeline, a filter bed adsorption and impurity removal zone is formed in the reactor shell below the water inlet, a multi-media filter bed is provided in the filter bed adsorption and impurity removal zone, a lower drain port is provided at the bottom of the filter bed adsorption and impurity removal zone, and the lower drain port is connected to the water inlet through a bottom external circulation pipeline.

[0006] Preferably, a water inlet distributor connected to the water inlet is provided at the center of the reactor shell, a partition plate located above the water inlet distributor, a lamp tube concentrically arranged on the partition plate, and a guide tube concentrically distributed outside the lamp tube are provided in the photochemical oxidation reaction zone, a connecting hole connected to the inner cavity of the lamp tube is provided in the middle of the partition plate, a plurality of ultraviolet lamp tubes are provided inside the lamp tube, the top of the lamp tube is gapped with the reactor shell, the top of the guide tube is tightly connected with the reactor, and the bottom of the guide tube is gapped with the partition plate.

[0007] Preferably, the photochemical oxidation reaction zone is also provided with a cleaning mechanism for cleaning the inner and outer walls of the lamp tube. The cleaning mechanism includes a plurality of screws rotatably arranged on the inner and outer sides of the lamp tube and a driving motor for driving the screws to rotate. The screws are respectively equipped with nuts, and the nuts are fixed with cleaning rings for cleaning the lamp tube walls at corresponding positions.

[0008] Preferably, the cleaning mechanism has three screws, one of which is located in the center of the lamp tube and directly connected to the drive motor, and the other two screws are symmetrically distributed on both sides of the lamp tube and are connected to the screws in the lamp tube through a transmission belt.

[0009] Preferably, a cross-shaped support frame is provided in the communicating hole, and a shaft seat for rotationally engaging with the lower end of the corresponding lead screw is provided at the center of the support frame.

[0010] Preferably, a sensor probe inlet is provided on the reactor shell in the middle of the photochemical oxidation reaction zone.

[0011] Preferably, a drug addition port is provided on the reactor shell at the bottom of the photochemical oxidation reaction zone.

[0012] Preferably, a main body exhaust port is provided at the top of the reactor shell.

[0013] Preferably, a first external circulation peristaltic pump is provided on the top external circulation pipeline between the overflow port and the water inlet.

[0014] Preferably, the lower drain outlet is connected to a plurality of interfaces, one of which is connected to the bottom external circulation pipeline, another is connected to the backwash pipeline, and another is connected to the pipeline drain outlet.

[0015] Preferably, a pipeline exhaust port is provided on the pipeline where the pipeline drain outlet is located at a position corresponding to the height of the upper overflow outlet.

[0016] Preferably, a second external circulation peristaltic pump is provided on the bottom external circulation pipeline.

[0017] Preferably, the multi-media filter bed includes anthracite, quartz sand and gravel filled in sequence from bottom to top.

[0018] A wastewater treatment system includes a raw water barrel, a water outlet barrel, a reagent barrel, and the above-mentioned photochemical oxidation circulating filter bed reactor. The raw water barrel is connected to the water inlet through a water inlet peristaltic pump, the water outlet barrel is connected to the upper drain outlet and the lower drain outlet respectively, and the reagent barrel is connected to the photochemical oxidation reaction zone on the photochemical oxidation circulating filter bed reactor through a reagent peristaltic pump.

[0019] The present invention combines the advantages of efficient mineralization of pollutants by photochemical oxidation technology with the effective turbidity reduction and deep adsorption of multi-media filter beds, which can significantly improve the overall performance of wastewater treatment systems and lay a certain application foundation for the industrial promotion of photochemical oxidation technology in the treatment of high-concentration, difficult-to-degrade organic wastewater. Specifically:

[0020] On the one hand, the plug flow internal circulation combined with the external circulation reflux system adopted in the present invention can avoid the influence of system turbulence caused by air aeration or mechanical stirring on the penetration performance of ultraviolet light in water while ensuring sufficient contact between wastewater and ultraviolet light source. It can significantly increase the penetration depth of ultraviolet light, especially short-wave ultraviolet light, in the wastewater to be treated, thereby effectively improving the treatment efficiency of photochemical oxidation degradation of pollutants and reducing system energy consumption.

[0021] On the other hand, the present invention combines photochemical degradation with multi-media filter bed impurity removal. The multi-media filter bed can serve as a pretreatment stage for the photochemical degradation reaction, effectively intercepting suspended impurities in the wastewater and reducing water turbidity, providing low-turbidity pretreated water for photochemical degradation and ensuring photochemical degradation efficiency. Furthermore, the multi-media filter bed impurity removal method can also serve as a post-photodegradation safeguard process, further absorbing and treating small amounts of pollutants and photoreaction oxidative degradation byproducts remaining in the water, achieving the goal of deeply purifying the treated water. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic structural diagram of a photochemical oxidation circulating filter bed reactor of the present invention;

[0023] Figure 2 for Figure 1 AA-axis cross-sectional structural diagram;

[0024] Figure 3 for Figure 1 Schematic diagram of the cross-sectional structure in the middle BB direction;

[0025] Figure 4 for Figure 1 Schematic diagram of the cross-sectional structure in the CC direction;

[0026] Figure 5 It is a structural schematic diagram of a wastewater treatment system of the present invention;

[0027] Markings in the figure: 1. Water inlet, 2. Separation plate, 3. Water inlet distributor, 301. Water distributor shell, 302. Water distribution hole, 4. Sensor probe inlet, 5. Overflow port, 6. Main body exhaust port, 7. Screw, 8. Lamp tube, 9. Drive motor, 10. Cleaning ring, 11. Flange cover, 12. Guide tube, 13. UV lamp, 14. Upper drain port, 15. Pipe exhaust port, 16. Pipe drain port, 17. Shaft seat, 18. Dosing port, 19. Lower drain port, 20. Reactor shell, 21. Multi-media filter bed, 22. Raw water barrel, 23. Reaction system stand, 24. Water inlet peristaltic pump, 25. First external circulation peristaltic pump, 26. Second external circulation peristaltic pump, 27. Photochemical oxidation circulating filter bed reactor, 28. Chemical barrel, 29. Water outlet barrel, 30. Chemical peristaltic pump. DETAILED DESCRIPTION

[0028] like Figure 1 As shown, a photochemical oxidation circulating filter bed reactor of the present invention has a main body of a vertical cylindrical reactor shell 20, and a flange cover 11 is provided on the top of the reactor shell 20 for sealing. A water inlet 1 is provided in the middle of the reactor shell 20, and an overflow port 5 and an upper drain port 14 are provided on the top. The overflow port 5 is connected to the water inlet 1 via a first external circulation peristaltic pump 25; a lower drain port 19 is provided at the bottom, and the lower drain port 19 is connected to the water inlet 1 via a second external circulation peristaltic pump 26. In addition, a sensor probe inlet 4 and a dosing port 18 are provided in the middle and upper part of the reactor shell 20, and a main body exhaust port 6 is provided at the flange cover 11. Through the above inlets and outlets, water, gas, chemicals and detection elements can be respectively entered and exited or installed.

[0029] The pipe of the water inlet 1 extends through the reactor shell 20 and is connected to the water distributor 3. Figure 4 As shown, the water inlet distributor 3 includes a water distributor housing 301 connected to the water inlet 1 and a plurality of water distribution holes 302 spaced apart at the top of the water distributor housing 301. After the wastewater enters the water inlet 1, it is discharged upward through the water distribution holes 302 into the reactor housing 20. The reactor housing 20 is divided into an upper photochemical oxidation reaction zone and a lower filter bed adsorption and impurity removal zone by the water inlet 1 and the water inlet distributor 3. The synergistic effect of the two significantly improves the overall performance of the wastewater treatment system. Specifically:

[0030] The bottom of the photochemical oxidation reaction zone is a circular separation plate 2, combined with Figure 1 and Figure 3 As shown, a connecting hole is provided in the middle of the partition plate 2, which is opposite to the water distributor 3, so that the water can enter the photochemical oxidation reaction zone through the connecting hole. A lamp tube 8 and a guide tube 12 are provided in sequence from the inside to the outside above the partition plate 2. The lamp tube 8 is made of quartz and has a sandwich layer, such as Figure 2As shown, a plurality of UV lamps 13 are evenly spaced along the circumference of the lamp tube 8, serving as light sources. Their primary emission wavelength is 254 nm. The lower end of the lamp tube 8 is tightly connected to the partition plate 2, allowing the inner cavity of the lamp tube 8 to communicate with the water distributor 3 through the connecting holes in the partition plate 2. The upper end of the lamp tube 8 is provided with multiple through-holes, allowing water in the lamp tube 8 to overflow. The upper end of the guide tube 12 is tightly connected to the flange cover 11, while the lower end is loosely fitted with the partition plate 2. Thus, a continuous internal circulation flow channel is formed in sequence inside the lamp tube 8, between the lamp tube 8 and the guide tube 12, and between the guide tube 12 and the inner wall of the reactor shell 20, so that the water body runs through the internal circulation flow channel under the promotion of the water inlet distributor 3, and the pollutants are homogenized during the flow process, thereby avoiding the influence of the system turbulence caused by air aeration or mechanical stirring in the prior art on the penetration performance of ultraviolet light in water, and can significantly increase the penetration depth of ultraviolet light, especially short-wave ultraviolet light, in the wastewater to be treated, thereby effectively improving the treatment efficiency of photochemical oxidation degradation of pollutants, while reducing the energy consumption of the system.

[0031] In order to prevent the light source intensity from being attenuated due to the contaminants adhering to the inner and outer walls of the lamp tube 8, the present invention also provides a cleaning mechanism that can clean the attachments on the inner and outer walls of the lamp tube 8 in real time. The cleaning mechanism includes cleaning rings 10 located inside and outside the lamp tube 8. The corresponding cleaning rings 10 are all distributed close to the wall of the lamp tube 8, and are lifted and lowered vertically under the action of the driving mechanism, thereby cleaning the attachments on the wall during the lifting process. The driving mechanism is a driving motor 9 and three lead screws 7. The driving motor 9 is fixed to the upper part of the flange cover 11, and its output shaft is distributed vertically through the flange cover 11. One of the three lead screws 7 is concentrically distributed in the lamp tube 8, and its upper end is directly connected to the output shaft of the driving motor 9, and the lower end is rotatably mounted on the following. Figure 3 As shown, it is fixed on the shaft seat 17 in the above-mentioned connecting hole through a cross-shaped support frame. Figure 2 As shown, a nut is mounted on the lead screw 7, and the nut is fixedly connected to the cleaning ring 10 located inside the lamp tube 8 through multiple connecting rods. That is, the lead screw 7 is driven to rotate by the driving motor 9. When the circumferential friction between the cleaning ring 10 inside the lamp tube 8 and the inner wall of the lamp tube 8 prevents the rotation of the lead screw 7, the nut moves along the lead screw 7 to drive the cleaning ring 10 inside the lamp tube 8 to rise and fall and clean the attachments on the inner wall of the lamp tube 8. The other two lead screws 7 are symmetrically distributed on both sides of the lamp tube 8, and their upper ends are respectively connected to the lead screw 7 inside the lamp tube 8 through synchronous pulleys (not shown in the figure), and their lower ends are respectively rotatably mounted on the following positions: Figure 3 In the axle seat 17 shown. Figure 2 In the figure, the external cleaning ring 10 of the lamp tube 8 is composed of two half rings, both of which are provided with a nut, and the nut is installed in conjunction with the lead screw 7 at the corresponding position, so that the two half rings are vertically lifted and lowered during the rotation of the corresponding lead screw 7 to clean the outer wall of the lamp tube 8.

[0032] A multi-media filter bed 21 is provided in the filter bed adsorption and impurity removal zone. The multi-media filter bed 21 comprises anthracite, quartz sand, and gravel, sequentially filled from bottom to top. A lower drain outlet 19 is provided at the bottom of the filter bed adsorption and impurity removal zone. This lower drain outlet 19 is connected to a tee. The left-hand interface of the tee is connected to the water inlet 1 via the aforementioned second external circulation peristaltic pump 26. The middle interface is connected to the backwash pipeline. The right-hand interface is connected to the pipeline drain outlet 16. A pipeline exhaust port 15 is provided on the pipeline where the pipeline drain outlet 16 is located, at a position corresponding to the height of the overflow port 5, to maintain a constant water pressure within the pipeline and the liquid surface pressure in the reactor shell 20.

[0033] The wastewater treatment system of the present invention, based on the above-mentioned photochemical oxidation loop filter bed reactor 27, further includes a raw water tank 22, a water outlet tank 29, a reagent tank 28, a reaction system stand 23, and conventional accessories such as flow meters, inlet and outlet valves, and pipelines. The raw water tank 22 holds the wastewater to be treated and is connected to the water inlet 1 via a water inlet peristaltic pump 24. The water outlet tank 29 holds the treated wastewater and is connected to the upper drain outlet 14 and the lower drain outlet 19, respectively. The reagent tank 28 is connected to the photochemical oxidation reaction zone on the photochemical oxidation loop filter bed reactor 27 via a reagent peristaltic pump 30. During the wastewater treatment process, the reactor is filled with a reaction reagent. The reaction reagent is typically a hydrogen peroxide solution, or a combination of one or more reagents such as persulfate, hypochlorite, and peracetic acid.

[0034] During conventional implementation of the water treatment system of the present invention, the wastewater to be treated stored in the raw water bucket 22 is added to the photochemical circulating filter bed reactor through the water inlet peristaltic pump 24. The water level of the reaction system rises to the upper part of the reactor shell 20 and flows out from the overflow port 5. It enters the first external circulation peristaltic pump 25 and is mixed with the raw water in the water inlet pipeline through the pipeline mixer and then returns to the reaction system. It enters the photochemical oxidation reaction zone through the water inlet distributor 3 in the middle of the reactor shell 20, and is fully mixed with the reaction reagent added by the reagent peristaltic pump 30. Under the irradiation of high-intensity ultraviolet light, the dissolved organic matter in the water is oxidized and degraded. The effluent of photochemical oxidation degradation reaches the set target and can be discharged directly from the upper drain port 14 at the upper part of the reactor shell 20. If it fails to meet the standard, the residual dissolved organic matter can be intercepted by the multi-media filter bed 21 at the lower part of the reactor shell 20, and the effluent is discharged to the water outlet bucket 29 through the pipeline drain port 16 after meeting the standard.

[0035] In the treatment of high-turbidity and high-chroma wastewater, since high-turbidity and high-chroma influent has a significant impact on the photochemical oxidation degradation efficiency of pollutants in the water, the left interface valve at the outlet 19 below the reactor shell 20 can be opened first. After the wastewater passes through the pretreatment process of interception and adsorption of suspended matter and large molecular organic pollutants in the water by the multi-media filter bed 21, it enters the reactor shell 20 through the water inlet 1. After entering, part of it continues to sink and be pretreated by the multi-media filter bed 21 to form a cycle, while part of it rises and enters the photochemical oxidation reaction zone for photoreaction degradation of organic pollutants. This can effectively intercept suspended impurities in the wastewater, reduce water turbidity, provide low-turbidity pretreated water for photochemical degradation, and ensure photochemical degradation efficiency.

[0036] During backwashing, the corresponding interface is opened to make the lower drain port 19 as water inlet, and the original water inlet 1 as water outlet. The backwash water is added to the reaction system through the bottom of the reactor shell 20. After flushing the multi-media filter bed 21, the cleaning water containing impurities flows back out through the water inlet distributor 3, completing the backwash regeneration of the multi-media filter bed 21.

Claims

1. A photochemical oxidation loop filter bed reactor, characterized in that: The invention comprises a vertical cylindrical reactor shell (20) and a water inlet (1) located in the middle of the reactor shell (20); a photochemical oxidation reaction zone is formed in the reactor shell (20) above the water inlet (1); an overflow port (5) and an upper drain port (14) are provided at the top of the photochemical oxidation reaction zone; the overflow port (5) and the water inlet (1) are connected via a top external circulation pipeline; a filter bed adsorption and impurity removal zone is formed in the reactor shell (20) below the water inlet (1); a multi-media filter bed (21) is provided in the filter bed adsorption and impurity removal zone; a lower drain port (19) is provided at the bottom of the filter bed adsorption and impurity removal zone; and the lower drain port (19) is connected to the water inlet (1) via a bottom external circulation pipeline; A water inlet distributor (3) connected to the water inlet (1) is provided at the center of the reactor shell (20); a partition plate (2) located above the water inlet distributor (3), a lamp tube (8) concentrically arranged on the partition plate (2), and a flow guide tube (12) concentrically distributed outside the lamp tube (8) are provided in the photochemical oxidation reaction zone; a connecting hole communicating with the inner cavity of the lamp tube (8) is provided in the middle of the partition plate (2); a plurality of ultraviolet lamp tubes (13) are provided inside the lamp tube (8); the top of the lamp tube (8) is gap-fitted with the reactor shell (20); the top of the flow guide tube (12) is tightly connected to the reactor; and the bottom of the flow guide tube (12) is gap-fitted with the partition plate (2).

2. The photochemical oxidation circulating filter bed reactor according to claim 1, wherein: A cleaning mechanism for cleaning the inner and outer walls of the lamp tube (8) is also provided in the photochemical oxidation reaction zone. The cleaning mechanism comprises a plurality of lead screws (7) rotatably arranged on the inner and outer sides of the lamp tube (8) and a drive motor (9) for driving the lead screws (7) to rotate. Nuts are respectively mounted on the lead screws (7), and cleaning rings (10) for cleaning the walls of the lamp tube (8) at corresponding positions are fixed on the nuts.

3. A photochemical oxidation loop filter bed reactor according to claim 2, characterized in that: The cleaning mechanism has three lead screws (7), one of which is located at the center of the lamp tube (8) and is directly connected to the drive motor (9), and the other two lead screws (7) are symmetrically distributed on both sides of the lamp tube (8) and are connected to the lead screws (7) in the lamp tube (8) through a transmission belt.

4. The photochemical oxidation circulating filter bed reactor according to claim 2, wherein: A cross-shaped support frame is provided in the communicating hole, and a shaft seat (17) for rotationally matching the lower end of the corresponding lead screw (7) is provided at the center of the support frame.

5. The photochemical oxidation loop filter bed reactor according to claim 1, wherein: A sensor probe inlet (4) is provided on the reactor shell (20) at the middle of the photochemical oxidation reaction zone.

6. The photochemical oxidation circulating filter bed reactor according to claim 1, wherein: A drug addition port (18) is provided on the reactor shell (20) at the bottom of the photochemical oxidation reaction zone.

7. The photochemical oxidation loop filter bed reactor according to claim 1, wherein: A main body exhaust port (6) is provided at the top of the reactor shell (20).

8. The photochemical oxidation circulating filter bed reactor according to claim 1, wherein: A first external circulation peristaltic pump (25) is provided on the top external circulation pipeline between the overflow port (5) and the water inlet (1).

9. The photochemical oxidation circulating filter bed reactor according to claim 1, wherein: The lower drain outlet (19) is connected to a plurality of interfaces, one of which is connected to the bottom external circulation pipeline, another is connected to the backwash pipeline, and another is connected to the pipeline drain outlet (16).

10. The photochemical oxidation loop filter bed reactor according to claim 9, characterized in that: A pipeline exhaust port (15) is provided on the pipeline where the pipeline drain port (16) is located at a position corresponding to the height of the upper overflow port (5).

11. The photochemical oxidation loop filter bed reactor according to claim 9, characterized in that: A second external circulation peristaltic pump (26) is provided on the bottom external circulation pipeline.

12. The photochemical oxidation loop filter bed reactor according to claim 1, wherein: The multi-media filter bed (21) comprises anthracite, quartz sand and gravel filled in sequence from bottom to top.

13. A wastewater treatment system, characterized in that: It comprises a raw water barrel (22), a water outlet barrel (29), a reagent barrel (28) and any one of the photochemical oxidation circulating filter bed reactors (27) as described in claims 1 to 12, wherein the raw water barrel (22) is connected to the water inlet (1) via a water inlet peristaltic pump (24), the water outlet barrel (29) is connected to the upper drain outlet (14) and the lower drain outlet (19) respectively, and the reagent barrel (28) is connected to the photochemical oxidation reaction zone on the photochemical oxidation circulating filter bed reactor (27) via a reagent peristaltic pump (30).

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