A system for treating paper towel production wastewater

Abstract

The application relates to the field of wastewater treatment, in particular to a paper towel production wastewater treatment system which comprises a pretreatment pool for paper towel wastewater, an additive pipe for feeding a floatation agent is fixedly connected to the bottom of the pretreatment pool, a transfer pool for temporarily placing separated fibers is arranged around the pretreatment pool, a circulating belt is arranged above the pretreatment pool and the transfer pool, a plurality of material moving hoppers are detachably connected to the transmission surface of the circulating belt, each material moving hopper can be moved to the liquid surface of the pretreatment pool and the top of the transfer pool to move fiber foam into the transfer pool, an ultrafiltration membrane assembly for separating residual fibers in wastewater is connected to the pretreatment pool, and a post-treatment pool for deep treatment and disinfection of wastewater is connected to the ultrafiltration membrane assembly, so that the fibers in the wastewater can be more comprehensively removed, and the fibers can be separated from the wastewater with high efficiency.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment, and in particular to a wastewater treatment system for paper towel production. Background Technology

[0002] The production of paper towels generates a large amount of wastewater containing fibers, which needs to be treated to meet standards before being discharged. The biggest difference between paper towel wastewater treatment and other wastewater treatment is that a relatively large amount of fibers need to be separated and recycled to reduce the pressure on subsequent wastewater treatment and improve resource utilization.

[0003] Some existing paper towel wastewater treatment methods use a scraper to first collect the fibers on the water surface. Then, in order to collect the remaining fibers in the water, a flocculant needs to be added to make the remaining fibers in the paper towel wastewater form fiber flocs and settle. For example, a papermaking wastewater pulp-water separation device with announcement number CN110204099B.

[0004] Regarding the aforementioned technologies, the scraper reciprocates to collect fibers from the water surface, but the collection efficiency is slow. This results in a high fiber content in the wastewater that subsequently enters the flocculation tank, requiring a long waiting time for the large amount of fibers to fully flocculate, leading to low overall fiber separation and recovery efficiency. Summary of the Invention

[0005] To improve the overall fiber separation and recycling efficiency, this application provides a paper towel production wastewater treatment system.

[0006] The paper towel production wastewater treatment system provided in this application adopts the following technical solution.

[0007] A wastewater treatment system for paper towel production includes a pretreatment tank into which wastewater from paper towel production enters. A dosing pipe for feeding flotation reagent is fixedly connected to the bottom of the pretreatment tank. A transfer tank is located around the pretreatment tank for temporary placement of separated fibers. A circulation belt is installed above the pretreatment tank and the transfer tank. Several transfer hoppers are detachably connected to the transmission surface of the circulation belt. Each transfer hopper can move directly below the liquid surface of the pretreatment tank and directly above the transfer tank to move fiber foam into the transfer tank. The pretreatment tank is connected to an ultrafiltration membrane module for separating remaining fibers from the wastewater. The ultrafiltration membrane module is connected to a post-treatment tank for further treatment and disinfection of the wastewater.

[0008] By adopting the above technical solution, flotation agent is first added to the pretreatment tank so that as many fibers as possible float on the surface of the liquid in the pretreatment tank to form fiber foam. The circulating belt continuously drives the transfer hopper to transfer the fiber foam to the transfer tank. Then, the paper towel wastewater with a small amount of fiber still enters the ultrafiltration membrane module so that the fibers in the paper towel wastewater can be fully separated and the overall fiber separation efficiency is high.

[0009] Optionally, the transfer hopper includes a hopper body detachably connected to the surface of the circulating belt drive, and a sealing plate rotatably connected to the lower opening of the hopper body located directly below the circulating belt. The sealing plate can close or open the opening of the hopper body to allow fibers to fall from the hopper body into the transfer pool.

[0010] By adopting the above technical solution, the fiber foam in the bucket can be lowered into the transfer pool during the continuous conveying process of the circulating belt.

[0011] Optionally, a worm gear is coaxially fixedly connected at the rotation point of the sealing plate, and the worm gear meshes with a worm. A side rack is detachably connected to the frame of the circulation belt located directly above the transfer pool. The side rack is used to drive the worm to rotate.

[0012] By adopting the above technical solution, the sealing plate is not easily rotated, so that the fiber foam in the hopper will not fall down randomly when the sealing plate needs to close the opening on one side of the hopper.

[0013] Optionally, a middle gear is coaxially fixedly connected to the end of the worm gear away from the sealing plate, and the middle gear can mesh with the side rack.

[0014] By adopting the above technical solution, the central gear will engage with the side rack when the bucket body moves to the predetermined position, and the central gear is less likely to enter the paper towel wastewater in the pretreatment tank.

[0015] Optionally, the sealing plate rotation point is located at the center point of its own surface so that rotating the sealing plate 180° can reseal the bucket.

[0016] By adopting the above technical solution, only a side rack of sufficient length is needed to allow the sealing plate to rotate 180° and then re-close the bucket body, simplifying the structural design.

[0017] Optionally, both the sealing plate and the hopper body have through-holes for liquid passage.

[0018] By adopting the above technical solution, the wastewater from paper towels inside the hopper can be discharged in a timely manner after the hopper picks up a portion of the fiber foam and moves upward with the circulation belt.

[0019] Optionally, the pretreatment tank includes a front tank for the paper towel wastewater to enter and a rear tank connected to the ultrafiltration membrane module. An upper partition and a lower partition are fixedly connected between the front tank and the rear tank. The bottom height of the upper partition is lower than the top height of the lower partition. The upper partition is closer to the front tank than the lower partition. The bottom of the lower partition is fixedly connected to the bottom surface inside the rear tank.

[0020] By adopting the above technical solution, larger particulate solids in the paper towel wastewater can be further prevented from entering the downstream tank, thereby performing preliminary treatment of the paper towel wastewater.

[0021] Optionally, the top of the upper baffle is lower than the liquid level in the pretreatment tank, and the pretreatment tank is detachably connected to a side pipe that can deliver airflow, with the lowest point of the circulation belt located at the center of all the side pipes.

[0022] By adopting the above technical solution, the fiber foam on the surface of the paper towel wastewater in the pretreatment tank can accumulate directly below the lowest point of the circulation belt, so that the bucket can pick up as much fiber foam as possible.

[0023] Optionally, a liquid distribution plate is detachably connected to the bottom of the pretreatment tank. The liquid distribution plate has several liquid distribution holes that are connected to the dosing pipe.

[0024] By adopting the above technical solution, the flotation agent can fully contact the paper towel wastewater in the pretreatment tank, so that as many fibers as possible in the paper towel wastewater can float to the surface and form fiber foam.

[0025] Optionally, the liquid distribution plate is also provided with several air holes, all of which are connected to a float tube that can deliver airflow. The diameter of the air holes is smaller than the diameter of the liquid distribution holes, and the position of the pretreatment tank connected to the ultrafiltration membrane module is lower than the height of the liquid distribution plate.

[0026] By adopting the above technical solution, the fibers in the paper towel wastewater can be fully floated, and the paper towel wastewater must pass through the air pores and liquid distribution pores to enter the ultrafiltration membrane module, which further enables the fibers in the paper towel wastewater to form fiber foam and float.

[0027] In summary, this application includes at least the following beneficial effects.

[0028] First, a flotation agent is added to the pretreatment tank so that as many fibers as possible float on the surface of the liquid in the pretreatment tank to form fiber foam. The circulating belt continuously drives the transfer hopper to transfer the fiber foam to the transfer tank. Then, the paper towel wastewater with a small amount of fiber still enters the ultrafiltration membrane module so that the fibers in the paper towel wastewater can be fully separated and the overall fiber separation efficiency is high. Attached Figure Description

[0029] Figure 1 This is a simplified piping diagram of this application; Figure 2 It is a structural schematic diagram showing the cross-section of the pretreatment tank, transfer tank, and protective shell, as well as the cross-section of the hopper body; Figure 3 yes Figure 2 Enlarged view of point A in the middle.

[0030] Explanation of reference numerals in the attached drawings: 1. Pretreatment tank; 2. Additive dosing pipe; 3. Transfer tank; 31. Protective shell; 4. Circulation belt; 41. Fore tank; 42. Rear tank; 43. Upper baffle; 44. Lower baffle; 45. Tank side pipe; 46. Liquid distribution plate; 47. Liquid distribution hole; 48. Air hole; 49. Float pipe; 5. Transfer hopper; 51. Ultrafiltration membrane module; 52. Posttreatment tank; 53. Hopper body; 54. Sealing plate; 55. Worm gear; 56. Side rack; 57. Central gear; 58. Worm; 59. Liquid passage hole. Detailed Implementation

[0031] The present application will be further described in detail below with reference to the accompanying drawings.

[0032] This application discloses a wastewater treatment system for tissue paper production, referring to... Figure 1 The system includes a pretreatment tank 1 with connecting pipes for the inflow of tissue paper wastewater. The pretreatment tank 1 is connected to a dosing pipe 2, which connects to an external centrifugal pump and a reagent tank for the introduction of flotation agents, ensuring that the fibers in the tissue paper wastewater form as much fiber foam as possible and float to the surface. A nearby transfer tank 3 is located around the pretreatment tank 1, where the fiber foam from the pretreatment tank 1 is temporarily placed until a certain amount is collected, at which point it is transferred for further treatment. The pretreatment tank 1 is connected to an ultrafiltration membrane module 51 for filtering and separating the remaining fibers in the tissue paper wastewater. The ultrafiltration membrane module 51 is connected to a posttreatment tank 52, which removes and disinfects some organic matter from the tissue paper wastewater through a combination of activated carbon adsorption, ozone oxidation, or chlorination.

[0033] Reference Figure 2 and Figure 3 A circulating belt 4 is detachably connected above the pretreatment tank 1 and the transfer tank 3. The circulating belt 4 is inclined, with its higher end directly above the transfer tank 3 and its lower end directly above the pretreatment tank 1. Several transfer hoppers 5 are evenly installed on the transmission surface of the circulating belt 4. Each transfer hopper 5 includes a hopper body 53 detachably connected to the transmission surface of the circulating belt 4. The hopper body 53 has two openings, one large and one small. The smaller opening of the hopper body 53 is away from the transmission surface of the circulating belt 4. A sealing plate 54 is rotatably connected to the smaller opening of the hopper body 53. The rotation point of the sealing plate 54 is located at the center point of the surface of the sealing plate 54. Several liquid passage holes 59 are evenly provided through both the hopper body 53 and the sealing plate 54. A worm gear 55 is coaxially fixedly connected to the sealing plate 54. The worm gear 55 meshes with a worm 58 rotatably connected to the outer wall of the hopper body 53. The length direction of the worm 58 is perpendicular to the transmission surface of the circulating belt 4.

[0034] Reference Figure 3A worm gear 58 is coaxially fixedly connected to a central gear 57. The central gear 57 is away from the worm wheel 55 and close to the transmission surface of the circulation belt 4, so that when the bucket 53 moves to the lowest point of the circulation belt 4, the central gear 57 is not easily allowed to enter the paper towel wastewater. Furthermore, the outer wall of the bucket 53 is detachably sealed with a protective shell 31 that surrounds the worm wheel 55 and the worm gear 58, and the central gear 57 is exposed outside the protective shell 31. A side rack 56 is detachably connected to the frame at the higher end of the circulation belt 4. The length direction of the side rack 56 is consistent with the inclination direction of the circulation belt 4. The side rack 56 can mesh with the central gear 57, so that when the bucket 53 moves directly above the transfer tank 3, the central gear 57 meshes with the side rack 56, so that the sealing plate 54 starts to rotate. After the sealing plate 54 rotates 180°, the central gear 57 disengages from the side rack 56, completing the release of the fiber foam in the bucket 53.

[0035] Reference Figure 2 The pretreatment tank 1 includes a front tank 41 and a rear tank 42. The upper part of the front tank 41, away from the rear tank 42, is where the paper towel wastewater enters. The bottom of the rear tank 42 is connected to the ultrafiltration membrane module 51. An upper baffle 43 and a lower baffle 44 are fixedly connected between the front tank 41 and the rear tank 42. The bottom height of the upper baffle 43 is lower than the top height of the lower baffle 44. The upper baffle 43 is closer to the front tank 41 than the lower baffle 44. The bottom of the lower baffle 44 is fixedly connected to the bottom surface inside the rear tank 42. The top height of the upper baffle 43 is lower than the liquid level of the pretreatment tank 1. This is so that while the upper baffle 43 and the lower baffle 44 effectively block large-volume particles in the paper towel wastewater, the upper baffle 43 is also less likely to block fibers on the liquid surface of the front tank 41. Furthermore, the pretreatment tank 1 is detachably connected to the perimeter of the tank edge pipe 45, which is connected to an external blower so that the fiber foam on the liquid surface of the pretreatment tank 1 gathers directly below the lowest point of the circulation belt 4.

[0036] Reference Figure 1 and Figure 2 A liquid distribution plate 46 is fixedly connected to the inner wall of the bottom of the rear tank 42. The liquid distribution plate 46 is fixedly connected to the vertical surface of the lower partition 44 away from the upper partition 43. Several liquid distribution holes 47 are evenly distributed through the surface of the liquid distribution plate 46. Each liquid distribution hole 47 is connected to the dosing pipe 2 so that the flotation agent can be sent into the paper towel wastewater through each liquid distribution hole 47. At the same time, several air holes 48 are also distributed through the liquid distribution plate 46. All air holes 48 are connected to the same float pipe 49. The float pipe 49 is connected to an external blower so that airflow is sent out from the air holes 48 and air bubbles are formed. Furthermore, the position of the pretreatment tank 1 connected to the ultrafiltration membrane module 51 is lower than the height of the liquid distribution plate 46 so that the paper towel wastewater can only enter the ultrafiltration membrane module 51 through the air holes 48 or the liquid distribution holes 47, thereby minimizing the amount of fiber entering the ultrafiltration membrane module 51.

[0037] The implementation principle of a tissue paper production wastewater treatment system according to an embodiment of this application is as follows: The tissue paper wastewater first enters the pre-pool 41 so that large-volume particles are blocked by the upper baffle 43 and the lower baffle 44. Then, the tissue paper wastewater flows to the post-pool 42, where the liquid distribution hole 47 delivers flotation agent and the air hole 48 delivers compressed air, causing fibers to float and form fiber foam. All the side pipes 45 concentrate all the fiber foam to the lowest point of the circulation belt 4. Then, the hopper 53 picks up the fiber foam and sends it into the transfer tank 3. The tissue paper wastewater then enters the ultrafiltration membrane module 51, and finally enters the post-treatment tank 52 for deep treatment and disinfection before being discharged.

[0038] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A wastewater treatment system for paper towel production, comprising a pretreatment tank (1) into which the wastewater from paper towel production enters, characterized in that: The pretreatment tank (1) is fixedly connected to the bottom of the addition pipe (2) for feeding flotation agent. There is a transfer tank (3) around the pretreatment tank (1) for temporary placement of separated fibers. A circulation belt (4) is provided above the pretreatment tank (1) and the transfer tank (3). Several transfer hoppers (5) are detachably connected to the transmission surface of the circulation belt (4). Each transfer hopper (5) can be moved to the liquid surface of the pretreatment tank (1) and the transfer tank (3) to move the fiber foam into the transfer tank (3). The pretreatment tank (1) is connected to an ultrafiltration membrane module (51) for separating the remaining fibers in the wastewater. The ultrafiltration membrane module (51) is connected to a posttreatment tank (52) for deep treatment and disinfection of the wastewater. The transfer hopper (5) includes a hopper body (53) detachably connected to the transmission surface of the circulation belt (4) and a sealing plate (54) rotatably connected to the lower opening of the hopper body (53) located directly below the circulation belt (4). The sealing plate (54) can close or open the opening of the hopper body (53) to allow fibers to fall from the hopper body (53) into the transfer pool (3). The sealing plate (54) is coaxially fixedly connected to a worm gear (55) at the rotation point, and the worm gear (55) meshes with a worm (58). The frame of the circulation belt (4) is detachably connected to a side rack (56) at the position directly above the transfer pool (3). The side rack (56) is used to drive the worm (58) to rotate. The worm (58) is coaxially fixedly connected to a middle gear (57) at the end away from the sealing plate (54), and the middle gear (57) can mesh with the side rack (56). The sealing plate (54) has its rotation point located at the center of its own surface so that the sealing plate (54) can re-close the bucket body (53) by rotating 180°. Both the sealing plate (54) and the hopper (53) have through-holes (59). The pretreatment tank (1) is detachably connected to a liquid distribution plate (46) at the bottom. The liquid distribution plate (46) has several liquid distribution holes (47) through it, and all the liquid distribution holes (47) are connected to the additive pipe (2). The liquid distribution plate (46) is also provided with several air holes (48), all of which are connected to a floating tube (49) that can deliver airflow. The diameter of the air holes (48) is smaller than the diameter of the liquid distribution holes (47). The position of the pretreatment tank (1) connected to the ultrafiltration membrane module (51) is lower than the height of the liquid distribution plate (46).

2. The paper towel production wastewater treatment system according to claim 1, characterized in that: The pretreatment tank (1) includes a front tank (41) into which paper towel wastewater enters and a rear tank (42) connected to the ultrafiltration membrane module (51). An upper partition (43) and a lower partition (44) are fixedly connected between the front tank (41) and the rear tank (42). The bottom height of the upper partition (43) is lower than the top height of the lower partition (44). The upper partition (43) is closer to the front tank (41) than the lower partition (44). The bottom of the lower partition (44) is fixedly connected to the bottom surface inside the rear tank (42).

3. The paper towel production wastewater treatment system according to claim 2, characterized in that: The top of the upper partition (43) is lower than the liquid level of the pretreatment tank (1). The pretreatment tank (1) is detachably connected to a pool-side pipe (45) that can deliver airflow. The lowest point of the circulation belt (4) is located at the center of all the pool-side pipes (45).

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