Membrane bioreactor for treating printing and dyeing wastewater

Abstract

The invention discloses a membrane bioreactor for treating printing and dyeing wastewater, which comprises a membrane bioreactor for treating printing and dyeing wastewater. Comprising a reaction tank, a bracket horizontally arranged in the reaction tank, a plurality of membrane assemblies distributed on the bracket side by side, four baffles supported in the reaction tank and an aeration pipe extending to the lower part of the bracket, the four baffles are arranged on the peripheral sides of the membrane assemblies in a surrounding manner, and the aeration pipe is used for aerating towards the membrane assemblies; generated bubbles act on membranes of the membrane assembly, circulating flow flows upwards along the outer sides of the four baffles under the blocking action of the outer sides of the four baffles, a small part of flow descending area exists on the upper portions of the inner sides of the four baffles, gas phase distribution is widened through the four baffles, and the gas gathering phenomenon is relieved. According to the membrane bioreactor provided by the utility model, a gas phase generated by the aeration effect is uniformly distributed among the membranes, and the surface stress of the membranes is more uniform, so that the aeration efficiency of the membrane bioreactor is improved, and the operation energy consumption of the membrane bioreactor is further reduced.

Description

Technical Field

[0001] The present application relates to the field of sewage treatment, and in particular to a membrane bioreactor for treating printing and dyeing wastewater. Background Art

[0002] Printing and dyeing wastewater treatment methods mainly include membrane separation technology to achieve wastewater reuse, reduce emissions, save water resources, and meet environmental protection and sustainable development requirements. Membrane bioreactor (MBR) is a combination of membrane separation technology and traditional activated sludge process. With its advantages such as stable and high-quality effluent and small footprint, it has gradually attracted people's attention and favor among many water treatment processes.

[0003] During the operation of MBR, due to the presence of filtration media (microfiltration / ultrafiltration membrane), large particles, colloids, large molecular soluble organic matter and other substances will gradually deposit on the membrane surface or enter the membrane pores to cause blockage, resulting in a decrease in membrane flux. In order to alleviate this phenomenon, a large amount of air is usually blown into the membrane pool from bottom to top, using the disturbance of the gas-liquid two-phase flow to slow down membrane pollution.

[0004] In actual applications, the gas phase formed by direct aeration of the aeration tube is only distributed above the aeration tube, between the membranes of the membrane assembly, and in the area above the membrane, that is, an upflow area with a higher gas content is formed between the membranes, and a downflow area with a lower gas content is formed outside the membrane. Among them, the upflow area is above the aeration tube, and there is an obvious gas-liquid interface, while a large area on both sides of the membrane is not covered by the gas phase. As the distance from the aeration tube gradually increases, the gas-liquid interface gradually shrinks toward the center until it reaches the vicinity of the liquid surface and then diffuses to the surroundings. Due to the push of the bubbles, the liquid flow rate above the aeration tube is greater than that in other areas, resulting in a smaller gas pressure than that of the surrounding areas. The liquid on both sides of the reactor forms a backflow to the membrane. The air in the aeration tube moves closer to the center of the reactor and pushes the bubbles toward the center. Near the liquid surface, part of the gas diffuses into the atmosphere, and the other part of the bubbles are pushed to the surroundings under the action of the overall circulating flow of the reactor, so that the gas phase formed by aeration in the aeration tube is not evenly distributed between the membranes of the membrane assembly, which is not effective in alleviating membrane pollution above and below the membrane. If the aeration volume is increased, the problem of excessive energy consumption is brought about, which to a certain extent limits the development of MBR technology. Therefore, how to make the gas phase between the membranes uniform under the premise of controlling membrane pollution, thereby improving aeration efficiency and reducing operating energy consumption, has become a problem that needs to be solved urgently in the current MBR application process. Summary of the invention

[0005] In order to control membrane pollution and make the gas phase generated by aeration evenly distributed between membranes to reduce operating energy consumption, the present application provides a membrane bioreactor for printing and dyeing wastewater treatment.

[0006] The membrane bioreactor for treating printing and dyeing wastewater provided in this application adopts the following technical solution: A membrane bioreactor for treating printing and dyeing wastewater comprises a reaction tank, a bracket horizontally arranged in the reaction tank, a plurality of membrane modules arranged side by side on the bracket, four baffles supported in the reaction tank and an aeration pipe extending to the bottom of the bracket, wherein the four baffles are arranged around the plurality of membrane modules, and the aeration pipe is used for aeration in the direction of the membrane modules.

[0007] By adopting the above technical scheme, the aeration pipe aerates the membrane assembly from bottom to top and acts on the diaphragm of the membrane assembly. Due to the push of the bubbles, the liquid flow rate above the aeration pipe is greater than that in other areas, resulting in a smaller air pressure than that around. The liquid on both sides of the reactor tends to move toward the center of the membrane reactor and pushes the bubbles toward the center. Under the blocking effect of the outer sides of the four baffles, the liquid on both sides of the membrane reactor flows upward along the outer sides of the four baffles, and there is a small downflow area on the upper inner sides of the four baffles. The four baffles make the gas phase distribution wider and the gas gathering phenomenon is alleviated, which is beneficial to make the gas phase generated by the aeration action evenly distributed between the diaphragms under the premise of controlling membrane pollution, so that the force on the surface of the membrane is more uniform, thereby improving the aeration efficiency of the membrane bioreactor and reducing the operating energy consumption of the membrane bioreactor.

[0008] Preferably, a bracket is provided in the reaction pool, and the bracket is provided with a connecting member for fixedly connecting with the four baffles.

[0009] By adopting the above technical solution, under the connecting and fixing action of the connecting components, the four-sided baffles are stabilized above the bracket and surround the membrane assembly, which is beneficial to improving the stability of the four-sided baffles.

[0010] Preferably, the aeration pipe is close to the bottom wall of the reaction tank.

[0011] In actual MBR operation, sludge particle deposition may occur, which reduces the suspended sludge concentration and causes the effluent water quality to fail to meet the standard. In addition, the reactor volume is not effectively utilized. By adopting the above technical solution, the distance between the aeration pipe and the bottom wall of the reaction tank is shortened, thereby increasing the flow velocity at the bottom of the reaction tank to cause disturbance, which is beneficial to improve the sludge particle deposition.

[0012] Preferably, the aeration holes on the aeration pipe are densely arranged along the length direction of the aeration pipe itself.

[0013] Near the bottom of the membrane, it is directly affected by the bubbles in the aeration pipe, and the gas content fluctuates strongly. By adopting the above technical solution and reducing the distance between the aeration holes, relatively dense bubbles can be generated on the extension path of the aeration pipe, reducing the fluctuation of the gas phase distribution at the bottom of the membrane, which is beneficial to reducing the probability that some areas on both sides of the membrane are not covered by bubble scouring. Moreover, by arranging dense aeration holes along the length direction of the aeration pipe, the membrane is completely within the range of the bubble action, and by reducing the aeration space distance, the bubbles also generate uniform shear force at the bottom of the membrane, which is beneficial to more uniform force on the membrane surface.

[0014] Preferably, the distance between the top of the four baffles and the liquid level of the reaction tank is equal to 5% of the liquid level of the reaction tank, and the distance between the bottom of the four baffles and the bottom wall of the reaction tank is equal to 25% of the height of the reaction tank.

[0015] By adopting the above technical solution, the distance between the aeration tube and the membrane is increased, so that the membrane is in the uniform action area of ​​the bubbles, the force on the membrane surface is more uniform, and it is in full contact with the bubbles. The average shear force on the membrane surface reaches the maximum, which is beneficial to improving the aeration efficiency of the membrane bioreactor.

[0016] Preferably, the aeration intensity of the aeration pipe in the reaction tank is 100m³ / min.

[0017] By adopting the above technical solution, the aeration intensity of the aeration pipe in the reaction tank is adjusted to 100m³ / min, and the membrane flux of the membrane reaction gas tends to be stable and reaches the maximum, which is conducive to improving the aeration efficiency.

[0018] Preferably, the bracket is detachably connected with an extension plate, and the extension plate is connected to the top of the four baffles.

[0019] By adopting the above technical solution, when the liquid level in the reaction tank changes, the height of the four baffles can be supplemented and adjusted by sliding the extension plate up and down to adapt to different liquid level heights in the reaction tank, which is beneficial to improving the applicability of the four baffles.

[0020] Preferably, the aeration pipe is installed and fixed on the bottom of the bracket.

[0021] By adopting the above technical solution, the aeration pipe is installed at the bottom of the bracket, and the bracket provides a connection point for the aeration pipe, which is beneficial to improving the stability of the aeration pipe.

[0022] In summary, the present application includes at least one of the following beneficial technical effects: 1. By arranging baffles around the outside of the membrane module, when the aeration pipe is working, aeration is carried out from bottom to top to the membrane module and acts on the membrane of the membrane module. Due to the push of the bubbles, the liquid flow rate above the aeration pipe is greater than that of other areas, resulting in a smaller air pressure than that of the surrounding areas, so that the liquid on both sides of the reactor tends to move toward the center of the membrane reactor and pushes the bubbles toward the center. Under the blocking effect of the outer sides of the four baffles, the liquid on both sides of the membrane reactor flows up along the outer sides of the four baffles, and there is a small downflow area on the upper inner side of the four baffles. The four baffles make the gas phase distribution wider and the gas gathering phenomenon is alleviated, which is conducive to evenly distributing the gas phase generated by aeration between the membranes under the premise of controlling membrane pollution, making the force on the membrane surface more uniform, thereby improving the aeration efficiency of the membrane bioreactor and reducing the operating energy consumption of the membrane bioreactor; 2. By reducing the spacing between aeration holes, relatively dense bubbles can be generated on the extension path of the aeration pipe, reducing the fluctuation of the gas phase distribution at the bottom of the membrane, which is conducive to reducing the probability that some areas on both sides of the membrane are not covered by bubble scouring. In addition, by arranging dense aeration holes along the length direction of the aeration pipe, the membrane is completely within the range of the bubble action, and by reducing the distance of the aeration space, the bubbles also generate uniform shear force at the bottom of the membrane, which is conducive to more uniform force on the membrane surface; 3. After the four baffles are set, the distance between the top of the four baffles and the liquid level of the reaction tank is equal to 5% of the liquid level of the reaction tank, and the distance between the bottom of the four baffles and the bottom wall of the reaction tank is equal to 25% of the height of the reaction tank, thereby increasing the distance between the aeration tube and the membrane, so that the membrane is in the uniform action area of ​​the bubbles, so that the force on the membrane surface is more uniform and fully in contact with the bubbles, and the average shear force on the membrane surface reaches the maximum, which is beneficial to improving the aeration efficiency of the membrane bioreactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of the overall structure of a membrane bioreactor for treating printing and dyeing wastewater according to an embodiment of the present application.

[0024] Figure 2 It is a schematic diagram of the connection between four baffles and brackets in a membrane bioreactor for treating printing and dyeing wastewater in an embodiment of the present application.

[0025] Explanation of the reference numerals: 1. reaction tank; 2. membrane assembly; 21. membrane; 3. four-sided baffles; 4. bracket; 5. connecting member; 6. aeration pipe; 61. aeration hole; 7. bracket. DETAILED DESCRIPTION

[0026] The following is combined with Figure 1-2 This application is described in further detail.

[0027] The present application discloses a membrane bioreactor for treating printing and dyeing wastewater. Figure 1 and Figure 2 , including a reaction tank 1, a bracket 7 horizontally arranged in the reaction tank 1, a plurality of membrane modules 2 arranged side by side on the bracket 7, four baffles 3 supported in the reaction tank 1, and an aeration pipe 6 extending to the bottom of the bracket 7. The membrane 21 of the membrane module 2 has a high-efficiency interception effect, so that the microorganisms are intercepted in the bioreactor. In this embodiment, the distribution direction of the plurality of membrane modules 2 is horizontal, the extension direction of the aeration pipe 6 is longitudinal, and there are multiple aeration pipes 6 arranged and distributed in the horizontal direction. The aeration pipe 6 is connected to the fan, wherein the four baffles 3 are arranged around the peripheral side of the plurality of membrane modules 2 arranged in the horizontal direction, and the aeration pipe 6 is used for aeration in the direction of the membrane module 2. Thus, a large amount of air is blown into the reaction tank 1, and the disturbance of the gas-liquid two-phase flow is used to reduce membrane pollution. In this embodiment, the reaction tank 1 can be extended longitudinally, and multiple groups of transversely distributed membrane modules 2 are arranged in the longitudinal direction to improve the treatment efficiency of the membrane bioreactor.

[0028] In this embodiment, the bracket 7 is a stainless steel structure, and the bracket 7 includes a plurality of support beams and connecting columns. The support beam is made of steel, and the ends are fixed to the connecting columns by welding. The connecting columns are made of high-strength cast iron, which enhances the overall stability of the support beam. The support beam is provided with a plurality of fixing holes distributed laterally, and each fixing hole is used to be fixedly connected to the bottom of the membrane assembly 2 to ensure that the membrane assembly 2 is firmly positioned in the reaction tank 1. In addition, a bracket 4 is vertically fixed to the bottom of the reaction tank 1, and the bracket 4 is longitudinally distributed at the two inner side walls of the reaction tank 1 and extends laterally, which is used to fix the four baffles 3 and the plurality of aeration pipes 6.

[0029] In this embodiment, the four-sided baffle 3 is formed by splicing four vertical baffles, and the thickness of each vertical baffle is 2 mm, which can effectively alleviate the influence of the circulating water flow on the bubble flow direction of the aeration pipe 6, and promote the uniform rise of bubbles. A connecting member 5 is fixed on the side of the bracket 4 facing the four-sided baffle 3. The connecting member 5 is specifically a connecting rod. The two ends of the connecting rod are respectively welded and fixed to the bracket 4 and the inner side of the four-sided baffle 3, thereby improving the stability of the four-sided baffle 3. In addition, the aeration pipe 6 extends from the outside of the reaction tank 1 to the bottom of the reaction tank 1. The aeration pipe 6 is close to the bottom of the reaction tank 1 and is fixed at the bottom position of the bracket 4. The bracket 4 provides an installation position for the aeration pipe 6, which is conducive to improving the stability of the aeration pipe 6. In addition, by shortening the distance between the aeration pipe 6 and the bottom wall of the reaction tank 1, the flow velocity at the bottom of the reaction tank 1 is increased, so as to cause water disturbance at the bottom of the reaction tank 1, which is conducive to improving the deposition of sludge particles.

[0030] In this embodiment, a plurality of aeration holes 61 are evenly distributed on the aeration tube 6, each aeration hole 61 has a diameter of 2 mm to 5 mm, and is densely arranged along the length direction of the aeration tube 6, and the spacing between adjacent aeration tubes 6 is 3 to 5 cm. This ensures that the bubbles are evenly distributed in the entire area of ​​the reaction tank 1 during the aeration process. The aeration holes 61 are connected to the main body of the aeration tube 6 by a reinforcing sheet, and the reinforcing sheet is made of corrosion-resistant metal material. There are four reinforcing sheets around each aeration hole 61 to strengthen the connection strength of the aeration hole 61 to prevent the aeration hole 61 from being blocked or damaged during long-term operation. A microporous filter is also provided at the aeration hole 61, and the microporous filter is made of polyester material with a pore size of 0.3 μm to filter large particles in the sewage to prevent them from clogging the aeration hole 61. This not only ensures the consistency of the aeration effect, but also improves the life of the aeration tube 6.

[0031] In this embodiment, the distance between the top of the four-sided baffles 3 and the liquid level of the reaction tank 1 is equal to 5% of the liquid level of the reaction tank 1, and the distance between the bottom of the four-sided baffles 3 and the bottom wall of the reaction tank 1 is equal to 25% of the height of the reaction tank 1. Thus, the distance between the aeration tube 6 and the membrane 21 is increased, so that the membrane 21 is in the uniform action area of ​​the bubbles, so that the force on the membrane surface is more uniform, and the membrane is fully in contact with the bubbles. The average shear force on the surface of the membrane 21 reaches the maximum, which is conducive to improving the aeration efficiency of the membrane bioreactor.

[0032] In this embodiment, the aeration intensity of the aeration pipe 6 in the reaction tank 1 is 100m³ / min, so that the membrane flux of the membrane reaction gas tends to be stable and reaches the maximum, which is conducive to improving the aeration efficiency.

[0033] In other embodiments, when the liquid level in the reaction tank 1 rises, an extension plate is detachably connected to the bracket 4 through a quick-release buckle. The thickness of the extension plate is consistent with that of the four steel plates and they are all made of stainless steel. The extension plate is connected to the top of the four baffles 3, thereby compensating for the height deficiency of the four baffles 3 to adapt to the different liquid level heights in the reaction tank 1, which is beneficial to improving the applicability of the four baffles 3.

[0034] The implementation principle of this embodiment is as follows: the aeration pipe 6 performs aeration from bottom to top toward the membrane assembly 2, and the generated bubbles act on the membrane 21 of the membrane assembly 2. Due to the push of the bubbles, the liquid flow rate above the aeration pipe 6 is greater than that in other areas, resulting in a smaller air pressure than that around, so that the liquid on both sides of the reactor forms a tendency to move toward the center of the membrane reactor and pushes the bubbles toward the center. Under the blocking effect of the outer sides of the four-sided baffles 3, the liquid on both sides of the reaction tank 1 flows upward along the outer sides of the four-sided baffles 3, and forms a small downflow area on the upper inner side of the four-sided baffles 3. Under the action of the four-sided baffles 3, the gas phase distribution becomes wider, and the gas gathering phenomenon is alleviated, thereby reducing the influence on the concentrated flow direction of the bubbles on the inner side of the baffle, which is beneficial to the uniform distribution of the gas phase generated by the aeration between the membranes 21 under the premise of controlling membrane pollution, so that the surface force of the membrane 21 is more uniform.

[0035] In addition, relatively dense bubbles are generated at the densely distributed aeration holes 61, which reduces the fluctuation of the gas phase distribution at the bottom of the membrane 21 and makes the membrane 21 completely within the range of the bubble action. By reducing the aeration space distance, the bubbles also generate uniform shear force at the bottom of the membrane 21, which is conducive to more uniform force on the membrane surface.

[0036] At the same time, the distance between the bottom of the four baffles 3 and the bottom wall of the reaction tank 1 is equal to 25% of the height of the reaction tank 1, thereby increasing the distance between the aeration pipe 6 and the membrane 21, so that the membrane 21 is in the uniform action area of ​​the bubbles, so that the force on the membrane surface is more uniform and fully in contact with the bubbles. The average shear force on the surface of the membrane 21 reaches the maximum, and the aeration intensity of the aeration pipe 6 in the reaction tank 1 is adjusted to 100m³ / min. The membrane flux of the membrane reaction gas tends to be stable and reaches the maximum, which is beneficial to improve the aeration efficiency of the membrane bioreactor, thereby reducing the operating energy consumption of the membrane bioreactor.

[0037] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A membrane bioreactor for treating printing and dyeing wastewater, characterized in that: The invention comprises a reaction tank (1), a bracket (7) horizontally arranged in the reaction tank (1), a plurality of membrane modules (2) arranged side by side on the bracket (7), four baffles (3) supported in the reaction tank (1), and an aeration pipe (6) extending to the bottom of the bracket (7), wherein the four baffles (3) are arranged around the plurality of membrane modules (2), and the aeration pipe (6) is used for aeration in the direction of the membrane modules (2).

2. The membrane bioreactor for treating printing and dyeing wastewater according to claim 1, characterized in that: A support (4) is provided in the reaction pool (1), and the support (4) is provided with a connecting member (5) for being fixedly connected to the four baffles (3).

3. The membrane bioreactor for treating printing and dyeing wastewater according to claim 1, characterized in that: The aeration pipe (6) is close to the bottom wall of the reaction tank (1).

4. The membrane bioreactor for treating printing and dyeing wastewater according to claim 1, characterized in that: The aeration holes (61) on the aeration pipe (6) are densely arranged along the length direction of the aeration pipe (6) itself.

5. The membrane bioreactor for treating printing and dyeing wastewater according to claim 1, characterized in that: The distance between the top of the four-sided baffles (3) and the liquid level of the reaction tank (1) is equal to 5% of the liquid level of the reaction tank (1), and the distance between the bottom of the four-sided baffles (3) and the bottom wall of the reaction tank (1) is equal to 25% of the height of the reaction tank (1).

6. The membrane bioreactor for treating printing and dyeing wastewater according to claim 1, characterized in that: The aeration intensity of the aeration pipe (6) in the reaction tank (1) is 100 m³ / min.

7. The membrane bioreactor for treating printing and dyeing wastewater according to claim 2, characterized in that: An extension plate is detachably connected to the bracket (4), and the extension plate is connected to the top of the four-sided baffles (3).

8. The membrane bioreactor for treating printing and dyeing wastewater according to claim 2, characterized in that: The aeration pipe (6) is installed and fixed on the bottom of the bracket (4).

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