A system for treating wastewater from water-based paint production

Abstract

The present invention relates to a system for treating wastewater produced by water-based paint, comprising a pretreatment unit, an oxidation treatment unit, a biochemical treatment unit and a deep treatment unit connected in sequence. The pretreatment unit comprises a regulating tank and a demulsification tank, which are used to regulate the water quality of the wastewater and demulsify the wastewater, so as to facilitate the discharge of the oil phase after demulsification and reduce the load of subsequent oxidation treatment; the oxidation treatment unit is used to treat refractory organic matter in the wastewater by chemical catalytic oxidation; the biochemical treatment unit comprises a micro-oxygen hydrolysis tank, an anoxic tank and an aerobic tank connected in sequence, the micro-oxygen hydrolysis tank is used to hydrolyze macromolecular organic matter and improve the biodegradability of the wastewater; the deep treatment unit comprises an oxidation adsorption sedimentation tank, which is used to treat residual organic matter in the wastewater by deep oxidation.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a system for treating wastewater from water-based paint production. Background Art

[0002] Water-based paint is a water-dispersed coating containing modified resins and surfactants. Compared to traditional paints containing harmful substances such as xylene, benzene, and formaldehyde, water-based paint is environmentally friendly, offers advantages such as wear resistance, aging resistance, flexibility, and ease of use, and poses minimal health risks. Consequently, its use is growing. However, the production process of water-based paint also raises the issue of wastewater treatment.

[0003] Wastewater from water-based paint production primarily originates from the production of the stock solution and the washing of equipment such as paint drums and filters. This wastewater is complex in composition, with major pollutants including emulsifiers, talc, and polymers. It also has high organic solvent content, is miscible with water, and exhibits poor biodegradability. If untreated or treated substandardly and discharged into rivers and lakes, this wastewater can cause serious water pollution. Summary of the Invention

[0004] In response to the above problems, the present invention provides a system for treating water-based paint production wastewater, comprising a pretreatment unit, an oxidation treatment unit, a biochemical treatment unit, and an advanced treatment unit connected in sequence. The pretreatment unit includes a regulating tank and a demulsification tank for regulating the wastewater quality and demulsification, facilitating the discharge of the oil phase after demulsification, and reducing the load of subsequent oxidation treatment; the oxidation treatment unit is used to treat refractory organic matter in the wastewater by chemical catalytic oxidation;

[0005] The biochemical treatment unit includes a micro-aerobic hydrolysis tank, an anoxic tank and an aerobic tank connected in sequence. The micro-aerobic hydrolysis tank is used to hydrolyze macromolecular organic matter to improve the biodegradability of wastewater.

[0006] The deep treatment unit includes an oxidation adsorption sedimentation tank, which is used for deep oxidation treatment of residual organic matter in the wastewater.

[0007] Optionally, a first oil phase outlet is provided at the top of the regulating tank, and a regulating water outlet is provided in the middle, and the regulating water outlet is connected to the inlet of the demulsification tank.

[0008] Optionally, the demulsification tank is connected to a reagent tank for quantitatively adding coagulants, flocculants and demulsifiers into the demulsification tank to remove water-insoluble pollutants; a second oil phase outlet is provided at the top of the demulsification tank, a demulsification water outlet is provided in the middle, and a mud hopper is provided at the bottom for discharging solid waste.

[0009] Optionally, the oxidation treatment unit includes an internal electrocatalytic oxidizer, and the demulsification water outlet is connected to the inlet of the internal electrocatalytic oxidizer.

[0010] Optionally, the micro-aerobic hydrolysis tank includes a hydrolysis water inlet area and a hydrolysis water outlet area, the outlet of the internal electrocatalytic oxidizer is connected to the top inlet of the hydrolysis water inlet area, passes through the hydrolysis water inlet area from top to bottom, and then enters the hydrolysis water outlet area from the connecting port at the bottom of the hydrolysis water inlet area, passes through the hydrolysis water outlet area from bottom to top, and then is discharged into the anoxic tank from the outlet at the top of the hydrolysis water outlet area.

[0011] The present invention proposes a new form of anoxic tank and aerobic tank, namely a horizontal well biochemical treatment device, comprising an upstream connecting pipe, a downstream connecting pipe and at least one U-shaped horizontal well connected in sequence, wherein the U-shaped horizontal well comprises an upstream well, an elbow and a downstream well connected in sequence;

[0012] The outlet end of the upstream connecting pipe is connected to the water inlet of the upstream well, and the water inlet end of the downstream connecting pipe is connected to the water outlet of the downstream well, so that the wastewater enters the U-shaped horizontal well through the upstream connecting pipe, and is discharged through the downstream connecting pipe after aeration and biochemical treatment in the U-shaped horizontal well; a flow-pushing device is provided in the downstream connecting pipe.

[0013] Optionally, the upstream well and the downstream well both have an intermittent casing structure, that is, they include several cylindrical hollow inner cylinders, which are arranged in sequence along the length direction of the upstream well or the downstream well, and there is a distance between adjacent inner cylinders; the well wall of the upstream well or the downstream well is an outer cylinder, and the inner cylinder and the outer cylinder are arranged concentrically.

[0014] Further optionally, in two adjacent inner tubes, the inlet of the inner tube on the downstream side is connected to the outlet of the variable diameter guide tube; the inlet of the variable diameter guide tube is connected to the inner wall of the outer tube and corresponds to the outlet of the inner tube on the upstream side; the diameter of the inlet of the variable diameter guide tube is larger than the diameter of the outlet, so that the sewage between the inner tube on the upstream side and the inner wall of the outer tube corresponding to the inner tube is completely drained into the interior of the inner tube on the downstream side along the inner wall of the variable diameter guide tube;

[0015] The inlets of several variable-diameter guide cylinders evenly divide the outer cylinder into several outer cylinder sections.

[0016] Further optionally, the outlet on the downstream side of the inner tube is provided with at least one return water pipe, which passes through the outer tube well wall and is then connected to the starting end (i.e., the upstream end) of the adjacent outer tube section on the downstream side, so that part of the outlet water in the inner tube on the upstream side is diverted along the return water pipe to between the inner and outer tubes on the downstream side, serving as the inlet water of the outer tube section.

[0017] Optionally, a plurality of second aeration tubes are evenly arranged on the inner wall of the outer tube and along the circumference of the outer tube, and aeration holes are densely distributed on the side walls of the second aeration tubes facing the interior of the outer tube, for aerating the water in the outer tube section;

[0018] The second aeration pipe extends along the upstream connecting pipe or the downstream connecting pipe and is then connected to the air supply device.

[0019] Optionally, a horizontal micro-oxygen liquid tube is provided at the center of the inner cylinder, and one micro-oxygen liquid tube passes through each inner cylinder of the upstream well or the downstream well, with both ends of the micro-oxygen liquid tube located at both ends of the outer cylinder; both ends of the micro-oxygen liquid tube pass through the outer cylinder and are connected to an external micro-oxygen aeration device;

[0020] The micro-oxygen liquid pipe is evenly provided with a number of hollow water outlet strips corresponding to the parts of each inner cylinder, which are used to input the wastewater after micro-oxygen aeration into the inner cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the process of the system for treating water-based paint production wastewater;

[0022] Figure 2 is a structural schematic diagram of the horizontal well biochemical treatment device;

[0023] Figure 3 It is a schematic diagram of the interior of an upstream well or a downstream well;

[0024] Figure 4 It is a schematic cross-sectional view of an upstream well or a downstream well (the variable diameter guide tube and return pipe are omitted);

[0025] Figure 5 Schematic diagram of the micro-oxygen liquid pipe and filler device.

[0026] In the accompanying drawings, 1-slider, 2-upstream connecting pipe, 3-downstream connecting pipe, 4-U-shaped horizontal well, 5-upstream well, 6-elbow, 7-downstream well, 8-inner cylinder, 9-outer cylinder, 10-variable diameter guide cylinder, 11-outer cylinder section, 12-return pipe, 13-second aeration pipe, 14-micro-oxygen liquid pipe, 15-water outlet bar, 16-guide rail, 17-filling part. DETAILED DESCRIPTION

[0027] This embodiment provides a system for treating wastewater from water-based paint production, such as Figure 1 As shown, it includes a pretreatment unit, an oxidation treatment unit, a biochemical treatment unit and a deep treatment unit connected in sequence. The pretreatment unit includes a regulating tank and a demulsification tank, which are used to adjust the water quality of the wastewater and demulsify, so as to facilitate the discharge of the oil phase after demulsification and reduce the load of subsequent oxidation treatment; the oxidation treatment unit is used to treat the refractory organic matter in the wastewater by chemical catalytic oxidation;

[0028] The biochemical treatment unit includes a micro-aerobic hydrolysis tank, an anoxic tank and an aerobic tank connected in sequence. The micro-aerobic hydrolysis tank is used to hydrolyze macromolecular organic matter to improve the biodegradability of wastewater.

[0029] The deep treatment unit includes an oxidation adsorption sedimentation tank, which is used for deep oxidation treatment of residual organic matter in the wastewater.

[0030] Optionally, the regulating tank is provided with a first oil phase outlet at the top and a regulating water outlet in the middle, connected to the inlet of the demulsification tank. Wastewater is fed into the regulating tank to achieve uniform water quality and oil-water separation. Water-insoluble solvents or oils float to the top and are discharged through the first oil phase outlet for further treatment. The water phase at the bottom is fed into the demulsification tank.

[0031] Optionally, the demulsification tank is connected to a reagent tank for quantitatively adding coagulants, flocculants and demulsifiers into the demulsification tank to remove water-insoluble pollutants; a second oil phase outlet is provided at the top of the demulsification tank, a demulsification water outlet is provided in the middle, and a mud hopper is provided at the bottom for discharging solid waste.

[0032] The wastewater discharged from the equalization tank also contains water-soluble organic matter, which is demulsified under the action of the demulsifier. After the oil and water are separated, the oil phase at the top of the demulsification tank is discharged through the second oil phase outlet for further treatment; after the wastewater reacts with the coagulant, the flocculent sinks into the mud hopper and is then discharged for further treatment.

[0033] Optionally, the oxidation treatment unit includes an internal electrocatalytic oxidizer, and the demulsification water outlet is connected to the inlet of the internal electrocatalytic oxidizer.

[0034] The internal electrocatalytic oxidizer relies on the active rare metal components in the fixed bed packing to form countless tiny galvanic cells. Under the action of the potential difference, a large number of primary ecological ions are generated. These ions have high chemical activity. Under the strong oxidizing action, they treat difficult-to-degrade organic pollutants, reduce biological toxicity, and improve the biodegradability of wastewater. The pH of the effluent from the internal electrocatalytic oxidizer is adjusted to neutral before entering the micro-aerobic hydrolysis tank. The internal electrocatalytic oxidizer is a conventional internal electrocatalytic oxidizer.

[0035] Optionally, the micro-aerobic hydrolysis tank includes a hydrolysis water inlet area and a hydrolysis water outlet area, the outlet of the internal electrocatalytic oxidizer is connected to the top inlet of the hydrolysis water inlet area, passes through the hydrolysis water inlet area from top to bottom, and then enters the hydrolysis water outlet area from the connecting port at the bottom of the hydrolysis water inlet area, passes through the hydrolysis water outlet area from bottom to top, and then is discharged into the anoxic tank from the outlet at the top of the hydrolysis water outlet area.

[0036] The micro-aerobic hydrolysis tank has the function of hydrolysis, which can convert large molecular substances into small molecular substances and improve the biodegradability of wastewater.

[0037] The present invention proposes a new form of anoxic pool and aerobic pool, namely a horizontal well biochemical treatment device, such as Figure 2-Figure 5 As shown, it includes an upstream connecting pipe 2, a downstream connecting pipe 3 and at least one U-shaped horizontal well 4 connected in sequence. The U-shaped horizontal well 4 includes an upstream well 5, an elbow 6 and a downstream well 7 connected in sequence.

[0038] The water outlet end of the upstream connecting pipe 2 is connected to the water inlet of the upstream well 5, and the water inlet end of the downstream connecting pipe 3 is connected to the water outlet of the downstream well 7, so that the wastewater enters the U-shaped horizontal well 4 through the upstream connecting pipe 2, and is discharged through the downstream connecting pipe 3 after aeration and biochemical treatment in the U-shaped horizontal well 4; a flow-pushing device is provided in the downstream connecting pipe 3.

[0039] Optionally, the U-shaped horizontal well 4 is buried in the ground in a horizontal form, which can greatly save space and has low sensitivity to the environment and climate, and is not affected by winter and summer temperatures;

[0040] The upstream connecting pipe 2 and the downstream connecting pipe 3 are both arranged obliquely for connecting to the above-ground biochemical treatment unit or deep treatment unit.

[0041] Optionally, a first aeration pipe is provided in the upstream connecting pipe 2, and aeration holes are densely distributed on the side wall of the first aeration pipe for aerating the water input into the upstream connecting pipe 2;

[0042] The flow-pushing device in the downstream connecting pipe 3 is a conventional flow-pushing device, which is used to push the water into the degassing tank.

[0043] Optionally, the elbow 6 is a 180° elbow 6 , so that the water in the upstream well 5 and the downstream well 7 flow in opposite directions.

[0044] Optionally, the horizontal well biochemical treatment device can be provided with several U-shaped horizontal wells 4 connected in sequence, so that the sewage flows through each U-shaped horizontal well 4 in sequence, thereby extending the residence time and improving the treatment effect. There are two forms of connecting several U-shaped horizontal wells in sequence: first, two U-shaped horizontal wells are arranged side by side, and the outlet of the downstream well of the previous U-shaped horizontal well is connected to the inlet of the upstream well of the next U-shaped horizontal well through an elbow; second, the downstream well of the previous U-shaped horizontal well serves as the upstream well of the next U-shaped horizontal well. Several U-shaped horizontal wells can be used as different biochemical treatment sections to implement AAO or AO treatment processes, and the aeration volume in the horizontal well can be controlled according to the actual oxygen demand.

[0045] Optionally, the upstream well 5 and the downstream well 7 both have an intermittent casing structure, that is, they include several cylindrical hollow inner tubes 8, which are arranged in sequence along the length direction of the upstream well 5 or the downstream well 7, and there is a distance between adjacent inner tubes 8; the well wall of the upstream well 5 or the downstream well 7 is an outer tube 9, and the inner tube 8 and the outer tube 9 are concentrically arranged.

[0046] Further optionally, in two adjacent inner tubes, the inlet of the inner tube on the downstream side is connected to the outlet of the variable diameter guide tube 10; the inlet of the variable diameter guide tube 10 is connected to the inner wall of the outer tube and corresponds to the outlet of the inner tube on the upstream side; the diameter of the inlet of the variable diameter guide tube 10 is larger than the diameter of the outlet, so that the sewage between the inner tube on the upstream side and the inner wall of the outer tube corresponding to the inner tube is completely drained into the interior of the inner tube on the downstream side along the inner wall of the variable diameter guide tube 10;

[0047] The inlets of several variable-diameter guide cylinders 10 evenly divide the outer cylinder into several outer cylinder sections 11 .

[0048] Further optionally, at least one return water pipe 12 is provided at the outlet on the downstream side of the inner tube, and the return water pipe 12 passes through the well wall of the outer tube and is connected to the starting end (i.e., the upstream end) of the outer tube section 11 adjacent to the downstream side, so that part of the outlet water in the inner tube on the upstream side is diverted along the return water pipe 12 to between the inner and outer tubes on the downstream side, serving as the inlet water of the outer tube section 11.

[0049] Optionally, a plurality of second aeration tubes 13 are evenly arranged on the inner wall of the outer tube and along the circumference of the outer tube, and aeration holes are densely distributed on the side walls of the second aeration tubes 13 facing the interior of the outer tube, for aerating the water in the outer tube section 11;

[0050] The second aeration pipe 13 extends along the upstream connecting pipe 2 or the downstream connecting pipe 3 and is then connected to the air supply device.

[0051] Optionally, a horizontal micro-oxygen liquid tube 14 is provided at the center of the inner cylinder. One micro-oxygen liquid tube 14 passes through each inner cylinder of the upstream well 5 or the downstream well 7, and both ends of the micro-oxygen liquid tube 14 are located at both ends of the outer cylinder; both ends of the micro-oxygen liquid tube 14 pass through the outer cylinder and are connected to an external micro-oxygen aeration device.

[0052] A plurality of hollowed-out water outlet strips 15 are evenly arranged at the portion of the micro-oxygen liquid pipe 14 corresponding to each inner cylinder, for inputting the wastewater after micro-oxygen aeration into the inner cylinder.

[0053] Further optionally, the micro-oxygen aeration device is installed on the ground and is a tank body with a micro-oxygen nano-aeration tube inside the tank body. The tank body inputs pre-treated (filtered and sanded) wastewater, which carries micro-oxygen bubbles after passing through the tank body and is input into the micro-oxygen liquid pipe 14.

[0054] In addition to the more traditional first aeration tube, the present invention also incorporates a micro-oxygen liquid tube 14 and a second aeration tube 13, which are provided in conjunction with the inner and outer tubes of the U-shaped horizontal well 4. Wastewater enters the upstream well 5 of the first U-shaped horizontal well 4 through the upstream connecting tube 2 (where the first aeration is also performed). Some of the wastewater enters the inner tube, flowing continuously along the sequentially arranged inner tubes for biochemical treatment. Some of the wastewater enters the first outer tube segment 11, where it undergoes aeration and oxygenation through the second aeration tube 13. This portion of wastewater then flows through the variable-diameter guide tube 10 into the second inner tube. Some of the wastewater in the first inner tube flows through the return pipe 12 into the second outer tube segment 11, where it continues aeration and oxygenation through the second aeration tube 13. The second aeration tube 13 observes the walls of each variable-diameter guide tube 10 on the inner wall of the outer tube. The wastewater in the second outer tube segment 11 then flows through the next variable-diameter guide tube 10 into the third inner tube, and the cycle continues.

[0055] The second aeration pipe 13 increases the oxygen content of the wastewater in the outer tube section 11, and then this part of the wastewater is input into the next inner tube, where it is mixed with the original wastewater in the inner tube and undergoes a biochemical reaction, thereby improving the treatment efficiency; part of the effluent on the downstream side of the inner tube is input into the next inner tube for further treatment, and part enters the next outer tube section 11 through the return pipe 12 for continued aeration and oxygenation, and then is input into the next inner tube, thus achieving the purpose of continuous dynamic oxygenation of part of the wastewater and continuous oxygenation of each inner tube.

[0056] A micro-oxygen liquid pipe 14 is installed within the inner cylinder to continuously feed wastewater containing micro-oxygen bubbles from an external micro-oxygen aeration device into the inner cylinder for a third oxygenation (in-situ oxygenation). For the same upstream well 5 or downstream well 7, the micro-oxygen liquid pipe 14 of the present invention can receive water from both ends, preventing insufficient oxygen downstream when only one end receives water. The micro-oxygen liquid pipe 14 provides a micro-oxygen environment within the inner cylinder, facilitating biochemical reactions within the inner cylinder.

[0057] Optionally, a movable filling device is provided in the inner cylinder, and the filling device includes a guide rail 16 and a plurality of filling parts 17 on the guide rail 16. The guide rail 16 is provided on both sides of the outer wall of the micro-oxygen liquid tube 14 and is provided along the length direction of the micro-oxygen liquid tube 14.

[0058] The filler part 17 is slidably connected to the guide rail 16 through the slider 1. The filler part 17 has an arc that bulges toward the upstream side or downstream side of the inner tube, so that the filler part 17 as a whole forms a spoon shape; the outer side of the filler part 17 is a mesh cage, and the inside is filled with carrier monomers, which can carry microorganisms and oxidize in contact with wastewater.

[0059] Further optionally, the packing portion 17 is connected to the slider 1 through a connecting handle, and the concave surface of the packing portion 17 on one side of the micro-oxygen liquid tube 14 faces the upstream side of the wastewater, and the convex surface of the packing portion 17 on the other side of the micro-oxygen liquid tube 14 faces the upstream side of the wastewater. The wastewater flowing through the inner tube impacts the concave surface of the spoon-shaped packing portion 17 and pushes all the packing portions 17 on this side to move downstream along the guide rail 16, thereby prompting all the packing portions 17 on the other side to move upstream along the guide rail 16, thereby realizing the movement of all the packing portions 17.

[0060] Traditional fillers are fixedly loaded in biochemical pools. The fillers near the inlet preferentially contact and treat wastewater with high pollutant concentrations, while the fillers near the outlet contact and treat wastewater with low pollutant concentrations. This results in some fillers being constantly loaded with high loads while others are constantly loaded with low loads. This is not conducive to the long-term stable operation of the biochemical pool. The fillers in traditional biochemical pools are difficult to move.

[0061] The present invention utilizes a U-shaped horizontal well 4 for wastewater treatment. Its elongated shape helps extend residence time and improve oxygen utilization. Furthermore, through ingenious design, a micro-oxygen liquid tube 14 extends through each inner barrel of either the upstream well 5 or the downstream well 7. The packing device also extends through each inner barrel. Wastewater pushes the packing section 17 on one side, thereby driving the packing on the other side. Because the protruding surface of the packing section 17 on the other side faces the wastewater, resistance is reduced. Consequently, all packing can circulate within the inner barrel along the micro-oxygen liquid tube 14, evenly distributing the treatment load across the packing section 17 and facilitating stable operation of the U-shaped horizontal well 4. The moving packing section 17 also serves as a stirring mechanism.

[0062] According to the different oxygen demands of the anoxic tank and the aerobic tank, for the anoxic tank, the oxygen supply of the second aeration pipe 13 is reduced, and the aeration volume of the micro-aerobic aeration device is reduced, so that the oxygen carried in the wastewater of the micro-aerobic liquid pipe 14 is reduced, and the first aeration pipe is not provided in the upstream connecting pipe 2;

[0063] As an anoxic tank, the two ends of the upstream connecting pipe 2 are respectively connected to the outlet at the top of the hydrolysis effluent zone and the water inlet of the upstream well 5, and the wastewater treated in the micro-aerobic hydrolysis zone is input into the U-shaped horizontal well 4 as the anoxic tank. Several U-shaped horizontal wells 4 can be connected in series to improve the anoxic treatment effect. The last U-shaped horizontal well 4 of the anoxic tank is connected to the upstream well 5 of the first U-shaped horizontal well 4 of the aerobic tank;

[0064] In the aerobic tank, several U-shaped horizontal wells 4 can also be connected in series to improve the aerobic treatment effect. The downstream well 7 of the last U-shaped horizontal well 4 in the aerobic tank is connected to the downstream connecting pipe 3, and the downstream connecting pipe 3 is connected to the sedimentation tank; the polyphosphate bacteria in the aerobic tank can efficiently remove phosphorus in the water, and the water produced by the aerobic tank is partially returned to the micro-aerobic hydrolysis tank and the anoxic tank. The reflux contains a trace amount of oxygen. The micro-aerobic environment can increase the tolerance concentration of sulfate ions and improve the impact resistance of the device. The micro-aerobic environment will block the conversion of sulfate ions in the water into H2S, thereby reducing the generation of odor.

[0065] Optionally, the biochemical treatment unit further comprises a sedimentation tank, in which the water treated in the aerobic tank is subjected to mud-water separation to remove SS in the water, and part of the sludge in the sedimentation tank is returned to the micro-aerobic hydrolysis tank and the anoxic tank, and the supernatant effluent from the sedimentation tank enters the deep treatment unit.

[0066] Optionally, the oxidation adsorption sedimentation tank uses the Fenton principle, adds an oxidant, and the Fe 3+ It has a strong hydrolysis tendency and can quickly combine with the -OH released by the decomposition of H2O2 to generate nano-iron hydroxide. The in-situ generated nano-iron hydroxide has a large specific surface area, large pore volume, and strong electrical neutralization ability. It has a strong adsorption capacity for organic matter in wastewater, ensuring that the effluent water quality is stable and meets the standards.

Claims

1. A system for treating wastewater from water-based paint production, characterized in that: It includes a pretreatment unit, an oxidation treatment unit, a biochemical treatment unit and a deep treatment unit connected in sequence. The pretreatment unit includes a regulating tank and a demulsification tank, which are used to adjust the wastewater quality and demulsify, so as to facilitate the discharge of the oil phase after demulsification and reduce the load of subsequent oxidation treatment; the oxidation treatment unit is used to treat the difficult-to-degrade organic matter in the wastewater by chemical catalytic oxidation; The biochemical treatment unit includes a micro-aerobic hydrolysis tank, an anoxic tank and an aerobic tank connected in sequence. The micro-aerobic hydrolysis tank is used to hydrolyze macromolecular organic matter to improve the biodegradability of wastewater. The deep treatment unit includes an oxidation adsorption sedimentation tank for deep oxidation treatment of residual organic matter in the wastewater; The anoxic pool and the aerobic pool include an upstream connecting pipe, at least one U-shaped horizontal well and a downstream connecting pipe connected in sequence, and the U-shaped horizontal well includes an upstream well, an elbow and a downstream well connected in sequence; The upstream well and the downstream well both have a discontinuous casing structure, including a plurality of cylindrical hollow inner cylinders arranged in sequence along the length direction of the upstream well or the downstream well, with spacing between adjacent inner cylinders; the well wall of the upstream well or the downstream well is an outer cylinder, and the inner cylinder and the outer cylinder are arranged concentrically; In two adjacent inner tubes, the inlet of the inner tube on the downstream side is connected to the outlet of the variable diameter guide tube; the inlet of the variable diameter guide tube is connected to the inner wall of the outer tube and corresponds to the outlet of the inner tube on the upstream side; the inlets of several variable diameter guide tubes evenly divide the outer tube into several outer tube sections; The outlet on the downstream side of the inner tube is provided with at least one return water pipe, which passes through the outer tube well wall and is then connected to the upstream end of the outer tube section adjacent to the downstream side, so that part of the outlet water in the inner tube on the upstream side is diverted along the return water pipe to between the inner and outer tubes on the downstream side as the inlet water of the outer tube section.

2. The system for treating water-based paint production wastewater according to claim 1, characterized in that: The regulating tank is provided with a first oil phase outlet at the top and a regulating water outlet at the middle, which is connected to the inlet of the demulsification tank; The demulsification tank is connected to the reagent tank and is used to quantitatively add coagulant, flocculant and demulsifier into the demulsification tank to remove water-insoluble pollutants; the top of the demulsification tank is provided with a second oil phase outlet, the middle is provided with a demulsification water outlet, and the bottom is provided with a mud hopper for discharging solid waste.

3. The system for treating water-based paint production wastewater according to claim 2, characterized in that: The oxidation treatment unit includes an internal electrocatalytic oxidizer, and the demulsification water outlet is connected to the inlet of the internal electrocatalytic oxidizer.

4. The system for treating water-based paint production wastewater according to claim 3, characterized in that: The micro-aerobic hydrolysis tank includes a hydrolysis water inlet area and a hydrolysis water outlet area. The outlet of the internal electrocatalytic oxidizer is connected to the top inlet of the hydrolysis water inlet area, passes through the hydrolysis water inlet area from top to bottom, then enters the hydrolysis water outlet area from the connecting port at the bottom of the hydrolysis water inlet area, passes through the hydrolysis water outlet area from bottom to top, and then is discharged into the anoxic tank from the outlet at the top of the hydrolysis water outlet area.

5. The system for treating water-based paint production wastewater according to claim 1, characterized in that: The outlet end of the upstream connecting pipe is connected to the water inlet of the upstream well, and the water inlet end of the downstream connecting pipe is connected to the water outlet of the downstream well, so that the wastewater enters the U-shaped horizontal well through the upstream connecting pipe, is aerated and biochemically treated in the U-shaped horizontal well, and then discharged through the downstream connecting pipe; A flow-pushing device is provided in the downstream connecting pipe.

6. The system for treating water-based paint production wastewater according to claim 5, characterized in that: The diameter of the inlet of the variable diameter guide tube is larger than the diameter of the outlet, so that the sewage between the upstream inner tube and the inner wall of the outer tube corresponding to the inner tube is all drained into the interior of the downstream inner tube along the inner wall of the variable diameter guide tube.

7. The system for treating water-based paint production wastewater according to claim 5, characterized in that: A plurality of second aeration tubes are evenly arranged on the inner wall of the outer tube and along the circumference of the outer tube, and aeration holes are densely distributed on the side walls of the second aeration tubes facing the interior of the outer tube, for aerating the water in the outer tube section; The second aeration pipe extends along the upstream connecting pipe or the downstream connecting pipe and is then connected to the air supply device.

8. The system for treating water-based paint production wastewater according to claim 5, characterized in that: A horizontal micro-oxygen liquid pipe is provided at the center of the inner cylinder. One micro-oxygen liquid pipe runs through each inner cylinder of the upstream well or the downstream well, and both ends of the micro-oxygen liquid pipe are located at both ends of the outer cylinder. Both ends of the micro-oxygen liquid pipe pass through the outer cylinder and are connected to an external micro-oxygen aeration device. The micro-oxygen liquid pipe is evenly provided with a number of hollow water outlet strips corresponding to the parts of each inner cylinder, which are used to input the wastewater after micro-oxygen aeration into the inner cylinder.

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