Membrane bioreactor modified from conventional settling basin, capable of facilitating selection and formation of granular sludge, wastewater treatment apparatus comprising same, and wastewater treatment method using same

Abstract

Disclosed is a membrane bioreactor modified from a conventional secondary circular settling basin for an aerobic granular sludge-membrane filtration process. Provided, according to one aspect of the present invention, is a membrane bioreactor comprising: a circular reactor body; an inlet pipe vertically disposed at the center of the reactor body, for supplying sludge and treated water discharged from an upstream bioreactor; a cylindrical feedwell concentrically installed on the outside of the inlet pipe; a membrane filtration device submerged in the reactor body to perform solid-liquid separation; a membrane support frame supporting the membrane filtration device; and a baffle installed between the membrane filtration device and an overflow weir so as to block discharge of solids with poor settleability due to an upward flow generated by the membrane filtration device.

Description

A membrane biological reactor of the improved type of conventional sedimentation tank capable of promoting the selection and formation of granular sludge, a wastewater treatment device including the same, and a wastewater treatment method using the same

[0001] The present invention relates to a wastewater treatment apparatus and method using aerobic granular sludge and a membrane biological reactor, and more specifically, to a wastewater treatment apparatus and method that converts an existing secondary sedimentation tank into a membrane biological reactor to efficiently separate granular sludge and reduce membrane fouling, thereby enabling stable maintenance and formation of granular sludge.

[0002] The content described in this section merely provides background information regarding the present embodiment and does not constitute prior art.

[0003] Standard activated sludge processes and their variations are generally used in wastewater treatment technologies. In these processes, the activity and settling properties of microorganisms have a significant impact on treatment efficiency. However, microorganisms have a specific gravity of only about 1.1 to 1.2, resulting in a very slow settling rate. Consequently, in conventional activated sludge processes, there is a problem in that the volume of the reaction tank must be increased to separate and concentrate microorganisms through settling.

[0004] To address these issues, processes utilizing submerged membrane bioreactors (MBRs) are being applied recently to replace solid-liquid separation by gravity sedimentation with membrane separation and to improve treatment efficiency by increasing the concentration of microorganisms within the reactor.

[0005] The membrane bioreactor (MBR) process offers the advantage of producing high-quality treated water suitable for reuse, along with high pollutant removal efficiency. Additionally, due to its small installation footprint and ease of expansion, it is widely applied in the treatment of urban and industrial wastewater where space is constrained. However, membrane bioreactors have the disadvantage that Mixed Liquor Suspended Solids (MLSS) effluent from the bioreactor can form a membrane fouling layer on the membrane surface, increasing the resistance to permeation of treated water. As a result, a large amount of energy is consumed for filtration of the treated water, and the lifespan of the membrane is shortened, leading to reduced filtration efficiency and increased operating costs.

[0006] Meanwhile, Aerobic Granular Sludge (AGS) possesses high density and settling properties, and can maintain high microbial concentrations, allowing for reduced reactor volume and site area while enabling cost savings. As such, it is attracting attention as a technology capable of overcoming the limitations of existing activated sludge processes. In particular, the aerobic granular sludge process has the advantage of simplifying the overall process by simultaneously removing organic matter, nitrogen, and phosphorus, thereby minimizing internal recirculation and sludge recirculation, which are essential in conventional nitrogen removal processes. However, in the aerobic granular sludge (AGS) process, small solids that do not settle, in addition to the granules, are not properly removed and are discharged along with the treated water, causing deterioration of treated water quality and difficulties in complying with water quality standards.

[0007] Therefore, various attempts are being made to combine membrane filtration technology with the Aerobic Granular Sludge (AGS) process to maximize granule recovery and ensure high treatment efficiency and stable treated water quality. Granular sludge is known to be highly effective in reducing membrane fouling due to its large particle size and porous structure. Furthermore, the AGS-MBR process offers the advantage of reduced sludge treatment costs by generating a small amount of sludge due to high active biomass concentration and efficient substrate decomposition.

[0008] However, this AGS-MBR process merely presents a concept that simply combines a membrane reactor and granules, and issues such as spatial constraints and the optimization of operating conditions still need to be resolved before it can be directly introduced into existing treatment plants for actual wastewater treatment.

[0009] One embodiment of the present invention provides a membrane biological reactor that improves upon an existing secondary sedimentation tank to utilize an existing wastewater treatment facility as an aerobic granular sludge-membrane filtration process. In particular, the reactor promotes the formation of granules in granular sludge with poor settling properties by generating shear force internally, and furthermore, improves membrane filtration efficiency by reducing membrane fouling on the membrane surface through the generation of longitudinal and transverse shear forces within the reactor. One objective is to provide a membrane biological reactor that improves upon an existing sedimentation tank in this manner.

[0010] In addition, one embodiment of the present invention optimizes the structure and operation method of the existing anaerobic tank upstream of the membrane bioreactor and includes a swing reactor for controlling the activity of the granules. Through this, there is an objective to provide a wastewater treatment device capable of stably forming and maintaining aerobic granular sludge by effectively responding to changes in the characteristics of the incoming wastewater, and a method for treating wastewater using the same.

[0011] According to one aspect of the present invention, a membrane biological reactor modified from a conventional circular sedimentation tank for application in an aerobic granular sludge-membrane filtration (AGS-MBR) process comprises: a circular reactor body; an inlet pipe vertically disposed in the center of the reactor body to supply sludge and treated water discharged from a preceding biological reactor to the reactor body; a cylindrical feed well disposed on the outside of the inlet pipe and installed concentrically with the inlet pipe; a membrane filtration device disposed to be immersed inside the reactor body and performing solid-liquid separation; a membrane support frame provided at the top of the reactor body to support the membrane filtration device while it is immersed inside the reactor body; and a partition wall installed between the membrane filtration device and the overflow weir, wherein the partition wall blocks solid matter with poor settling properties from being discharged through the overflow weir by the upward flow generated by the membrane filtration device. Provides

[0012] According to one aspect of the present invention, the feed well changes the flow of treated water and sludge flowing in through the inlet pipe downward so that the treated water and sludge are supplied into the main body of the reaction tank, wherein the uppermost part of the feed well is located below the effective water level of the main body of the reaction tank, and as the treated water and sludge transferred to the upper part of the reaction tank by the upward flow formed by the membrane filtration device flow into the upper part of the feed well and move downward, a longitudinal shear force is induced to be generated inside the reaction tank.

[0013] According to one aspect of the present invention, the feedwell further comprises an inclined plate portion having a plurality of inclined pieces arranged therein, wherein the plurality of inclined pieces are installed in a distributed manner at an angle to connect the inlet pipe and the feedwell, and the flow of fluid discharged from the bottom of the feedwell is characterized in that it rotates in one direction along the inclination direction of the inclined pieces and is discharged into the reaction tank.

[0014] According to one aspect of the present invention, the partition wall is characterized in that its uppermost portion is formed higher than the upper portion of the overflow weir, and its lowermost portion is formed to be located lower than the lower portion of the membrane filtration device.

[0015] According to one aspect of the present invention, the membrane support frame is installed such that one end is fixed to an overflow weir formed on the side wall of the main body of the reactor and the other end is fixed to the outer circumference of the feed well, thereby connecting the center of the main body of the reactor and the side wall, and is characterized by having at least two or more provided in the main body of the reactor.

[0016] According to one aspect of the present invention, the membrane bioreactor further comprises a maintenance walkway installed across the top of the body of the reactor and utilized as a path for a worker, wherein the maintenance walkway is rotatable with respect to the center of the body of the reactor.

[0017] According to one aspect of the present invention, the membrane support frame comprises an upper support frame, one end of which is connected to the lower part of the maintenance walkway and the other end of which is extended toward the main body of the reaction tank to support the membrane filtering device, and a lower support frame, which is extended from the lower part of the membrane filtering device toward the bottom of the main body of the reaction tank and has a sludge collection device connected to its end to collect sludge settled on the bottom of the main body of the reaction tank, wherein as the maintenance walkway rotates, the membrane filtering device fixed to the membrane support frame rotates with respect to a rotation axis at the center of the main body of the reaction tank.

[0018] According to one aspect of the present invention, a wastewater treatment device is provided that operates as an aerobic granule sludge-membrane filtration process including the membrane bioreactor, comprising: an anaerobic tank that receives wastewater to induce the growth of granule sludge and decompose organic matter; a simultaneous nitrification / denitrification reactor that receives the granule sludge grown in the anaerobic tank and wastewater to remove nitrogen in the wastewater using the granule sludge; a granule separation tank that receives the wastewater from which nitrogen has been removed and the granule sludge to separate them into granule sludge and supernatant through solid-liquid separation; and a membrane bioreactor that receives the supernatant separated in the granule separation tank to filter solid matter secondarily and improve the settling ability of the granule sludge in the supernatant.

[0019] According to one aspect of the present invention, a swing reactor is further included between the anaerobic tank and the simultaneous nitrification / denitrification reactor, and the swing reactor receives sludge and wastewater that have passed through the anaerobic tank and is operated aerobically or anaerobically depending on the concentration of organic matter in the wastewater.

[0020] According to one aspect of the present invention, the granule sludge separated from solid in the granule separation tank is returned to the anaerobic tank.

[0021] According to one aspect of the present invention, granular sludge with improved settling properties, which is subjected to shear force in the membrane bioreactor, is settled to the bottom of the membrane bioreactor, and the settled granular sludge is returned to the swing reactor or the simultaneous nitrification / denitrification reactor.

[0022] According to one aspect of the present invention, the anaerobic tank is divided into multiple zones internally so as to be composed of a plurality of unit anaerobic tanks, and each unit anaerobic tank is characterized by being operated repeatedly in a cycle comprising a step in which only granular sludge is introduced without the introduction of wastewater, a step in which only wastewater is introduced, and stirring is performed, a step in which wastewater is continuously introduced, and a step in which wastewater and granules within the anaerobic tank are discharged into a swing reactor.

[0023] According to one aspect of the present invention, the anaerobic tank is composed of three unit anaerobic tanks, and while stirring and wastewater inflow are performed in the first anaerobic tank, granule input is initiated in the second anaerobic tank and the process of wastewater input and stirring is performed sequentially, and while stirring and wastewater inflow are performed in the second anaerobic tank, granule input is initiated in the third anaerobic tank and each unit anaerobic tank is operated sequentially.

[0024] According to one aspect of the present invention, a method for treating wastewater using an aerobic granular sludge-membrane filtration process including the membrane bioreactor comprises: a step of receiving wastewater and decomposing organic matter in an anaerobic environment and inducing the growth of granular sludge; a step of adjusting the activity of granular sludge by varying the environment to aerobic or anaerobic depending on the concentration of organic matter in the wastewater and the wastewater and granular sludge that have passed through the anaerobic environment; a step of removing nitrogen in the wastewater by performing nitrification and denitrification reactions by the granular sludge with adjusted activity; a step of separating the wastewater and granular sludge from which nitrogen has been removed into granular sludge and treated water by solid-liquid separation, and returning the separated granular sludge to a step for inducing the growth of the granular sludge; and receiving the solid-liquid separated treated water into the membrane bioreactor and further removing residual solid matter in the supernatant by membrane filtration. A wastewater treatment method comprising an aerobic granular sludge-membrane filtration process including a step of discharging treated water is provided.

[0025] According to one aspect of the present invention, the membrane bioreactor applies a shear force to granule sludge with relatively poor settling ability that was not separated in the granule separation tank to improve the settling ability of the granule sludge, and the granule sludge with improved settling ability received from the shear force in the membrane bioreactor settles to the bottom of the membrane bioreactor and is returned to the swing reactor and / or simultaneous nitrification / denitrification reactor.

[0026] According to one aspect of the present invention, the step of inducing the growth of the granule sludge is performed in an anaerobic tank, wherein the anaerobic tank is characterized by being operated repeatedly in a cycle comprising a step in which only granule sludge is introduced without the introduction of wastewater, a step in which only wastewater is introduced, and a step in which stirring is performed while wastewater is continuously introduced, and a step in which wastewater and granules within the anaerobic tank are discharged to a downstream process.

[0027] As described above, according to one aspect of the present invention, a conventional secondary sedimentation tank is modified into a membrane biological reactor for an aerobic granule sludge-membrane filtration process. At this time, by making maximum use of the structure of the conventional sedimentation tank to form turbulence inside the reactor, the occurrence of membrane fouling is reduced and the settling ability of granules with somewhat poor settling ability is improved so that they can be recovered into the process, thereby reducing the cost of membrane maintenance and sludge treatment in addition to improving the treatment efficiency of the process.

[0028] In addition, the configuration of the biological reactor, including an anaerobic tank and a swing reactor, is optimized so that an environment for the formation and maintenance of granules can be created upstream of the membrane filtration process, thereby ensuring that the aerobic granule sludge-membrane filtration process can be maintained stably. This has the advantage of ensuring stable treated water quality using aerobic granule sludge regardless of changes in the characteristics of the influent wastewater.

[0029] Figure 1a is a cross-sectional view of a typical circular sedimentation tank equipped in a wastewater treatment facility.

[0030] FIG. 1b is a cross-sectional view of a membrane bioreactor of the improved conventional sedimentation tank type according to one embodiment of the present invention.

[0031] Figure 2 is a conceptual diagram illustrating the basic structure of an air lift reactor applied for the formation of granular sludge.

[0032] FIG. 3 is a cross-sectional view and a plan view illustrating the specific structure of a feedwell included in a membrane bioreactor according to one embodiment of the present invention.

[0033] FIG. 4 is a cross-sectional view of a conventional sedimentation tank improved membrane bioreactor according to another embodiment of the present invention.

[0034] FIG. 5 is a drawing showing a wastewater treatment device including a membrane bioreactor according to one embodiment of the present invention.

[0035] FIG. 6 is a diagram showing the operation cycle of three anaerobic tanks in a wastewater treatment device according to one embodiment of the present invention.

[0036] FIG. 7 is a flowchart illustrating a method for treating wastewater including a membrane bioreactor according to one embodiment of the present invention.

[0037] The present invention is susceptible to various modifications and may have various embodiments, and specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the invention to specific embodiments, and it should be understood that the invention includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the invention. Similar reference numerals have been used for similar components in the description of each drawing.

[0038] Terms such as first, second, A, B, etc., may be used to describe various components, but said components should not be limited by said terms. These terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any of a plurality of related described items.

[0039] When it is stated that one component is "connected" or "connected" to another component, it should be understood that while it may be directly connected or connected to that other component, there may also be other components in between. On the other hand, when it is stated that one component is "directly connected" or "directly connected" to another component, it should be understood that there are no other components in between.

[0040] The terms used in this application are used merely to describe specific embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, terms such as "comprising" or "having" should be understood as not precluding the existence or addition of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification.

[0041] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains.

[0042] Terms such as those defined in commonly used dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant technology, and should not be interpreted in an ideal or overly formal sense unless explicitly defined in this application.

[0043] In addition, each component, process, procedure, or method included in each embodiment of the present invention may be shared within a scope that is not technically contradictory to one another.

[0044] The membrane bioreactor (MBR) combined with the aerobic granular sludge (AGS) process according to the present invention is intended for application to existing wastewater treatment facilities, and the secondary sedimentation tank located downstream of the bioreactor in the existing wastewater treatment facility is modified and used as a reactor for the AGS-MBR process.

[0045] In biological water treatment processes for general wastewater treatment, a secondary sedimentation tank is used downstream of the biological reactor to separate the treated water from the solids, i.e., sludge.

[0046] Figure 1a is a cross-sectional view of a typical circular sedimentation tank equipped in a wastewater treatment facility.

[0047] Secondary sedimentation tanks have circular and rectangular structures, and among them, circular sedimentation tanks can form a stable water flow from a hydraulic perspective. Accordingly, they are typically used as physical treatment facilities for separating solid pollutants in treated water.

[0048] Referring to FIG. 1a, the circular sedimentation tank is configured to include a circular sedimentation tank reaction body (10), a maintenance walkway (20), a driving unit (23), a moving wheel (25), an inlet pipe (30), an inlet water discharge port (33), a feed well (40), a sludge collection device (50), a sludge discharge pipe (60), a scum collector (70), a scum baffle (73), a scum discharge pipe (75), a scum collection box (80), a treated water collection unit (90), and an overflow weir (95).

[0049] A maintenance walkway (20) used as a worker's movement path is provided at the top of the main body (10) of the circular sedimentation tank. The maintenance walkway (20) is installed so that one end can rotate relative to the center of the main body (10) of the sedimentation tank. To this end, a drive unit (23) for rotating the maintenance walkway (20) is provided at the center of the main body (10) of the circular sedimentation tank. Additionally, the maintenance walkway (20) includes a wheel (25) on the lower side of the other end, and the wheel (25) is configured to move along a rail (not shown) provided on the upper side of the side wall of the main body (10).

[0050] The maintenance walkway (20) may further include walkway railings (not shown) for the safety of workers during movement and maintenance of the sedimentation tank.

[0051] The inlet pipe (30) is positioned at the bottom of the circular sedimentation tank body (10) and receives treated water from a biological reactor (not shown) containing solid contaminants, i.e., sludge, and supplies it into the interior of the tank body (10). The inlet pipe (30) is formed to extend vertically upward from the center of the tank body (10), and an inlet water discharge port (33) is formed at the end of the inlet pipe (30). Accordingly, the inlet water discharge port (33) discharges the treated water and sludge received through the inlet pipe (30) to the top of the sedimentation tank. To this end, the inlet water discharge port (33) may be formed in the form of a plurality of through holes arranged in a circumferential direction along the outer surface of the end of the inlet pipe (30).

[0052] The feed well (40) is installed to surround the outer periphery of the inflow pipe (30), particularly the inflow discharge port (33). The feed well (40) changes the direction of the flow of the sludge and treated water as the treated water containing sludge discharged from the inflow discharge port (33) passes through the internal space of the feed well (40). In addition, it causes the sludge and treated water to spread throughout the interior of the sedimentation tank. Through this process, the kinetic energy of the treated water itself, including the discharge pressure of the treated water flowing into the sedimentation tank, is reduced, thereby inducing smooth sedimentation of solids.

[0053] A sludge collection device (50) is provided at the bottom of the main body (10) of the sedimentation tank, and rotates at the bottom of the main body (10) to move the sludge settled at the bottom to the center of the main body (10). The sludge collection device (50) rotates together with the maintenance walkway (20) by means of a driving unit (23) provided at the center of the main body (10), and gradually transports the sludge widely settled on the bottom of the main body (10) to the center of the main body (10).

[0054] Sludge transferred to the center of the main body (10) by the sludge collection device (50) is discharged to the outside through the sludge discharge pipe (60). A portion of the sludge discharged to the outside is discarded, and the remainder is returned to a biological reactor (not shown).

[0055] A scum collector (70) is rotatably installed on the upper side of the circular sedimentation tank body (10) to remove and collect scum floating in the circular sedimentation tank and discharge it into a scum collection box (80). One end of the scum collector (70) is connected to the center of the reaction tank body (10) and rotates on the upper side of the sedimentation tank relative to the center. In particular, it is installed on the same rotation axis to rotate in conjunction with a sludge collection device (50) and a maintenance walkway (20) that rotate on the bottom of the reaction tank body (10), so that they rotate together by means of a driving unit (23).

[0056] A scum baffle (73) is fixedly installed on the upper side of the reaction tank body (10) where the scum collector (70) is installed. The scum baffle (73) has an open top structure to receive scum collected as the scum collector (70) rotates, and a scum discharge pipe (75) is connected to the bottom. The scum introduced into the scum baffle (73) is discharged to the scum collection box (80) through the scum discharge pipe (75).

[0057] A scum collection box (80) can be installed on the outer wall of the main body of the reaction tank (10), and the scum collection box (80) is connected to a scum baffle (73) through a scum discharge pipe (75).

[0058] The treated water collection unit (90) is positioned on the outer wall of the main body of the reaction tank (10) and is formed outside the overflow weir (95) formed on the side wall of the main body of the reaction tank (10). As the sludge in the treated water flowing into the circular sedimentation tank settles, a supernatant separated in the upper layer is formed, and this supernatant flows over the overflow weir (95) and is collected into the treated water collection unit (90). The treated water collection unit (90) is connected to a separate discharge pipe (not shown) to discharge the collected supernatant outside the sedimentation tank.

[0059] As described above, the present invention can be applied as a membrane bioreactor to which aerobic granular sludge is applied by modifying an existing secondary sedimentation tank, particularly a circular sedimentation tank, into a membrane tank. A membrane bioreactor modified from an existing circular sedimentation tank is illustrated in FIG. 1b.

[0060] FIG. 1b is a cross-sectional view of a membrane bioreactor of the improved conventional sedimentation tank type according to one embodiment of the present invention.

[0061] Referring to FIG. 1b, the membrane biological reactor (100) includes a reactor body (110), a maintenance walkway (120), a drive unit (123), a moving wheel (125), a walkway handrail (127), an inlet pipe (130), an inlet water discharge port (135), a feed well (140), a sludge discharge pipe (150), a sludge removal unit (160), an overflow weir (165), a membrane filtration device (170), a membrane support frame (173), a partition wall (175), and a sludge collection device (not shown).

[0062] As described above, since the present invention applies a conventional circular sedimentation tank by modifying it into a membrane bioreactor, it includes most of the same configuration as the conventional circular sedimentation tank shown in FIG. 1a. Therefore, below, we will describe the configuration modified to modify the conventional circular sedimentation tank shown in FIG. 1a into a membrane bioreactor.

[0063] The membrane biological reactor (100) of the improved conventional sedimentation tank according to the present invention is equipped with a membrane filtration device (170) inside the reactor body (110) to perform solid-liquid separation by the membrane and filter and discharge the treated water.

[0064] In addition, the membrane biological reactor (100) of the improved conventional sedimentation tank according to the present invention can promote the formation of granules and strengthen the granular structure by providing appropriate shear stress to the granular sludge using a membrane filtration device (170) installed inside the reactor.

[0065] Accordingly, the membrane filtration device (170) is positioned to be immersed inside the main body of the reaction tank (110), and at least two membrane filtration devices (170) can be installed in the space inside the main body of the reaction tank (110).

[0066] The membrane filtration device (170) may be a filtration device for an MBR process using a conventional immersion-type membrane module. Accordingly, the unit membrane filtration device (170) is provided with a plurality of membrane modules (not shown) installed and fixed inside it according to the processing capacity.

[0067] For example, the membrane included in the membrane filtration device (170) may be a hollow fiber membrane, and the unit membrane filtration device (170) may include a membrane frame (not shown) on which a plurality of membrane modules (not shown) are installed.

[0068] Additionally, the unit membrane filtration device (170) is equipped with a plurality of air diffusers (not shown) at the bottom to supply air to the membrane surface so as to detach contaminants attached to the membrane surface during the membrane filtration process. At this time, the air diffusers may be connected to an external air supply device. Furthermore, the unit membrane filtration device (170) is equipped with a water collection pipe (not shown) at the top to collect the treated water filtered through the membrane module and discharge it to the outside.

[0069] The membrane support frame (173) installs and supports the membrane filtration device (170) while it is immersed inside the main body of the reaction tank (110). To this end, the membrane support frame (173) is fixed at one end to the feed well (140) and at the other end to the overflow weir (165) on the side wall of the main body of the reaction tank (110), respectively, and is installed in the form of a frame connecting the center of the main body of the reaction tank (110) and the side wall. The membrane filtration device (170) is installed with its upper end fixed to the membrane support frame (173), so that the entire membrane module is immersed below the upper end of the overflow weir (165), that is, below the effective water level of the main body of the reaction tank (110), and it is preferable that the membrane support frame (173) is also installed below the effective water level. In addition, the membrane support frame (173) is provided to correspond to the number of membrane filtration devices (170) immersed inside the main body of the reaction tank (110).

[0070] When membrane filtration is performed by a membrane filtration device (170) immersed inside the main body of the reaction tank (110), air is supplied from an air diffuser (not shown) provided in the membrane filtration device (170). Due to the strong air sprayed upward from the bottom of the membrane filtration device (170), turbulence is formed around the membrane module (not shown), and sludge attached to the surface of the membrane is detached. At this time, in the area where the membrane filtration device (170) is installed inside the main body of the reaction tank (110), a strong upward flow is generated by the air supplied from the bottom of the membrane filtration device (170).

[0071] By utilizing the upward flow formed inside the reaction tank body (110) according to the operation of the membrane filtration device (170), the formation of aerobic granular sludge (AGS) flowing into the reaction tank body (110) can be promoted.

[0072] Generally, the formation of granules requires the application of a high concentration of organic matter and an appropriate level of shear stress. In particular, an appropriate level of shear stress is known to induce the aggregation of microorganisms and strengthen the granule structure. Since air-lift reactors are most commonly utilized for the formation of granules, a circulation structure of an air-lift reactor can be formed inside the membrane bioreactor (100) of the present invention.

[0073] Figure 2 is a conceptual diagram illustrating the basic structure of an air-lift reactor applied for the formation of granular sludge.

[0074] An air-lift reactor (200) has a hollow tube (210) disposed inside, and an aeration pipe (230) is disposed outside the tube (210) in the lower region of the reactor (200).

[0075] The air-lift reactor (200) injects air into the interior to allow fluid to circulate within the reactor (200). To this end, a tube (210) installed inside divides the interior of the reactor (200) into an upward flow zone (250) and a downward flow zone (270). For example, the upward flow zone (250) may be formed on the outside of the tube (210), and the downward flow zone (270) may be formed on the inside of the tube (210). In this case, an upward flow of fluid is formed in the upward flow zone (250) by air injected through the diffuser (230). The fluid rising along the outer circumference of the tube (210) in this manner flows into the interior of the tube (210) from the top of the tube (210), descends through the downward flow zone (270), and moves to form a circulating fluid flow.

[0076] In this way, as the up / down flow is repeatedly formed along the structure of the relatively narrow and high reaction tank, the flow velocity increases, and as a result, strong shear force can be generated, and this shear force can be applied to the granular sludge and strengthen the granular structure.

[0077] Referring again to FIG. 1b, the membrane bioreactor (100) of the present invention, which is an improved type of conventional sedimentation tank, can form the structure of the aforementioned air-lift reactor by utilizing the configuration of a feedwell (140) formed in the center of the reactor body (110).

[0078] The feedwell (140) of the membrane bioreactor (100) of the present invention is formed in a cylindrical structure, similar to the feedwell (40) of a conventional sedimentation tank, and surrounds the outer circumference of the inlet pipe (130), so that the direction of the water flow can be changed inside the body of the reactor (110).

[0079] To this end, the uppermost part of the feedwell (140) is installed so as to be spaced downward by a predetermined distance from the effective water level of the reaction tank body (110), and the vertical length of the feedwell (140) can be formed to be longer than that of the feedwell (40) of the existing sedimentation tank. In particular, it is preferable that it be extended further downward toward the reaction tank body (110) than that of the existing feedwell (40). In addition, the feedwell (140) can reduce the phenomenon of contaminants adhering to the surface of the separation membrane by inducing a downward flow within the feedwell (140) in one direction and generating a lateral shear force in the reaction tank body (110). The detailed structure of such a feedwell (140) will be described later in FIG. 4.

[0080] Below, the process of forming a circulation structure by air-lift inside a membrane bioreactor (100) according to one embodiment of the present invention is described in more detail.

[0081] Wastewater containing sludge that has been primarily treated at the front end of the membrane biological reactor (100) is transported from the bottom to the top of the reactor body (110) through the inlet pipe (130) and discharged through the inlet water discharge port (135) at the end of the inlet pipe (130). The discharged wastewater moves downward along the internal space of the feedwell (140) and is supplied to the internal space of the reactor body (110).

[0082] At this time, the inflow water discharge port (135) is formed in the shape of a plurality of through holes arranged in a circumferential direction along the outer surface of the end of the inflow pipe (130), so that the wastewater supplied through the inflow pipe (130) is evenly discharged in various directions.

[0083] As described above, since a strong upward flow is formed inside the main body of the reaction tank (110) by the air supplied from the membrane filtration device (170), the wastewater flowing in from the bottom of the feedwell (140) moves back to the top of the reaction tank along the upward flow. At this time, the wastewater containing granular sludge that was not filtered through the membrane filtration device (170) moves back into the inside of the feedwell (140) near the effective water surface of the main body of the reaction tank (110) and moves rapidly downward to the bottom of the main body of the reaction tank (110) along the inner space of the feedwell (140).

[0084] That is, in the area where the membrane filtration device (170) is placed, the granule sludge moves upward by the air supply and then rapidly descends again along the feedwell (140) from the top of the reaction tank body (110), and through this process, shear force is applied to the granule sludge, so that it can be formed into a granule with a harder structure.

[0085] Furthermore, the upward flow generated inside the main body of the reactor (110) and the movement of the granular sludge circulating therein generate turbulence in the area around the membrane filtration device (170), which is very effective in reducing membrane fouling on the surface of the membrane.

[0086] Meanwhile, a partition wall (175) may be further provided inside the membrane bioreactor (100). The partition wall (175) is installed between the membrane filtration device (170) and the overflow weir (165) to prevent the upward flow generated by the membrane filtration device (170) from overflowing through the overflow weir (165).

[0087] To this end, the uppermost part of the bulkhead (175) should be formed higher than the upper part of the overflow weir (165), and the lowermost part should be positioned lower than the lower part of the membrane filtration device (170).

[0088] The upward flow formed by the membrane filtration device (170) by the partition wall (175) can be entirely converted into a downward flow through the feed well (140). Through the repetition of this upward / downward flow circulation, the granular sludge with improved settling properties sinks to the bottom of the reaction tank body (110), and is finally collected by a sludge collection device (not shown) and discharged to the outside through the sludge discharge pipe (150).

[0089] Meanwhile, in the area formed on the outer edge of the partition wall (175), upward flow and turbulence are hardly formed by the membrane filtration device (170), so sludge with high settling ability settles in the outer edge of the partition wall (175), and solid matter with poor settling ability exists in a floating state and is primarily discharged to the sludge removal unit (160) through the overflow weir (165) as supernatant water, and then discharged to the outside of the main body of the reaction tank (110). In the existing sedimentation tank main body (10), the sludge removal unit (160) functions as a treated water collection unit (90) that collects the overflowed supernatant water, but in the membrane biological reaction tank (100), it collects solid matter with poor settling ability (sludge) that overflows through the overflow weir (165).

[0090] In one embodiment of the present invention, the discharge of solid matter with poor settling properties through the overflow weir (165) can be performed intermittently.

[0091] During normal operation, the amount of treated water discharged from the membrane filtration device (170) is set to a value excluding the amount of water returned from the membrane biological reactor (100) to the upstream biological reactor (not shown) from the amount of water flowing into the main body of the reactor (110). As a result, the water level inside the main body of the reactor (110) is maintained lower than the overflow weir (165). When it is necessary to discharge solid matter with poor settling properties inside the reactor (100), the amount of treated water from the membrane filtration device (170) is reduced to raise the water level of the main body of the reactor (110) above the height of the overflow weir (165), so that solid matter with poor settling properties can be discharged to the sludge removal unit (160) through the overflow weir (165).

[0092] This discharge action of the present invention can achieve substantially the same effect as the selective discharge of solids with poor settling properties performed in a conventional treatment process using granular sludge. Accordingly, the membrane bioreactor (100) of the present invention can effectively separate solids (sludge) with excellent settling properties and flocs with poor settling properties, and can improve the overall treatment efficiency of the wastewater treatment device by returning only the sludge with excellent settling properties to the upstream bioreactor.

[0093] FIG. 3 is a diagram illustrating the specific structure of a feedwell of a membrane bioreactor according to one embodiment of the present invention.

[0094] Figure 3 (a) is a cross-sectional view of a feedwell (140) according to one embodiment of the present invention, and Figure 3 (b) is a plan view of the feedwell (140).

[0095] Referring to FIG. 3, a feedwell (140) according to one embodiment of the present invention may include an inclined plate portion (310) having a plurality of inclined pieces (320) arranged inside.

[0096] The inclined plate portion (310) may be placed in the lower region of the feedwell (140). In particular, it is preferable to place it within 2 / 3 of the total height of the feedwell (140) from the bottom of the feedwell (140).

[0097] The inclined plate section (310) induces the flow of wastewater and solids flowing downward inside the feedwell (140) to rotate in one direction, and forms a water flow inside the reaction tank body (110) in the same direction as the inclination of the inclined plate section (310).

[0098] To this end, each of the plurality of inclined pieces (320) connects the outer circumference of the inlet pipe (130) and the inner circumference of the feed well (140), and is installed in a distributed manner so as to be inclined in one direction to have an inclination of a certain range. The inclination of the inclined pieces (320) may be, for example, in the range of 20 to 60°.

[0099] The flow of wastewater and solids discharged from the lower part of the feedwell (140) through the inclined plate section (310) can generate a transverse shear force against the membrane filtration device (170). This transverse shear force, together with the longitudinal shear force caused by the air supplied from the membrane filtration device (170), can effectively reduce the adhesion of contaminants to the membrane surface.

[0100] The membrane bioreactor (100) of the present invention combines an aerobic granular sludge (AGS) and a membrane bioreactor (MBR), and improves upon the existing circular sedimentation tank to maximize the use of the existing structure, while controlling the flow of the granular sludge internally to promote granule formation and significantly reduce membrane fouling of the membrane.

[0101] FIG. 4 is a cross-sectional view illustrating a conventional sedimentation tank improved membrane bioreactor according to another embodiment of the present invention.

[0102] Since the membrane bioreactor (400) according to another embodiment of the present invention includes the same configuration as the membrane bioreactor (100) of one embodiment, only the differences between it and the membrane bioreactor (100) of one embodiment shown in FIG. 1b will be explained below.

[0103] Referring to FIG. 4, a membrane bioreactor (400) according to another embodiment of the present invention differs from the configuration of the membrane bioreactor (100) of one embodiment in that it includes a maintenance walkway (410) and a walkway railing (417), and a membrane support frame (420) that supports and fixes a membrane filtration device (170), and further includes a sludge collection device (430), a washing water supply unit (440), and a spray nozzle (445).

[0104] The maintenance walkway (410) is installed to cross the top of the reaction tank body (110) and is formed with a length equal to the diameter of the reaction tank body (110). The walkway railing (417) is also formed to extend along the entire length of the walkway (410). The maintenance walkway (410) is equipped with wheels (125) at both ends, and the maintenance walkway (410) can rotate with respect to the center of the reaction tank body (110) by moving along a rail (not shown) provided on the upper side of the side wall of the reaction tank body (110).

[0105] The membrane support frame (420) installs and supports the membrane filtration device (170) while it is immersed inside the main body of the reaction tank (110). At this time, the membrane support frame (420) is formed with an upper support frame (420a) and a lower support frame (420b).

[0106] The upper support frame (420a) is formed to extend from the lower part of the maintenance walkway (410) toward the main body of the reactor (110) and is configured to support the upper part of the membrane filtration device (170). The upper support frame (420a) is formed integrally with the maintenance walkway (410) and is configured so that the membrane filtration device (170) rotates together with the rotational movement of the maintenance walkway (410). In this case, the upper support frame (420a) may be included on one side and the other side of the maintenance walkway (410) respectively, centered on the rotation axis of the main body of the reactor (110), and as a result, two membrane filtration devices (170) may be installed.

[0107] Typically, the membrane filtration device (170) collects the treated water through a collection pipe (not shown) located above the membrane filtration device (170) and discharges it by communicating with a treated water discharge pipe (not shown). As described above, the membrane filtration device (170) within the reaction tank body (110) according to another embodiment of the present invention rotates in conjunction with a maintenance walkway (410), so the collection pipe (not shown) of the treated water provided in the membrane filtration device (170) can be connected to a treated water discharge pipe (not shown) fixed to the outside of the reaction tank body (110) through a rotary joint, etc., to discharge the treated water that has undergone membrane filtration.

[0108] Meanwhile, the lower support frame (420b) is formed to extend downward from the bottom of the membrane filtration device (170) toward the bottom of the reaction tank body (110).

[0109] The sludge collection device (430) is connected to the end of the lower support frame (420b) formed by extending from the membrane filtration device (170), and as the membrane filtration device (170) rotates together with the rotation of the maintenance walkway (410), the sludge collection device (430) also rotates in conjunction, moving the solid matter (sludge) settled on the bottom of the reaction tank body (110) to the center of the reaction tank body (110) so that it can be easily discharged to the outside through the sludge discharge pipe (150).

[0110] As the membrane filtration device (170) rotates within the main body (110) of the reaction vessel, a shear force is generated, and as a result, the phenomenon of contaminants adhering to the surface of the membrane can be reduced. At this time, it is preferable that the rotation direction of the membrane filtration device (170) be opposite to the direction of the water flow formed by the inclined plate portion (310) inside the feed well (140).

[0111] A washing water supply unit (440) may be included between the partition wall (175) and the membrane filtration device (170). The washing water supply unit (440) is formed to extend into the interior of the reaction tank body (110), and a plurality of spray nozzles (445) are formed at the end. The spray nozzles (445) are configured to spray washing water toward the surface of the membrane. Accordingly, as the membrane filtration device (170) rotates inside the reaction tank body (110) around a central rotation axis and passes in front of the spray nozzles (445), membrane contaminants on the surface of the membrane can be effectively removed by the high-pressure washing water sprayed from the spray nozzles (445).

[0112] It is preferable to use water that does not contain solids when the washing water is sprayed into the main body (110) of the reaction tank through the washing water supply unit (440). It is effective to circulate a portion of the treated water discharged through the membrane filtration device (170) to the washing water supply unit (440) for washing.

[0113] That is, as the membrane filtration device (170) rotates inside the reaction tank body (110) in conjunction with the maintenance walkway (410), the progression of membrane fouling can be prevented by shear force, and repeated cleaning can be performed using the spray nozzle (445) in conjunction with the rotational movement of the membrane filtration device (170), thereby stably maintaining the filtration performance of the membrane filtration device (170). Furthermore, as membrane fouling is reduced, the frequency of cleaning out of place (COP), which involves lifting the membrane filtration device (170) to the outside for cleaning, can be reduced, thereby minimizing the shutdown of the facility due to membrane cleaning and maintaining the continuity of the treatment facility and the amount of treated water. In addition, the lifespan of the membrane can be extended, and energy and costs incurred due to cleaning can be reduced.

[0114] Below, we examine a wastewater treatment device to which an AGS-MBR process is applied using the aforementioned improved conventional sedimentation tank type separation membrane biological reactor (100).

[0115] FIG. 5 is a drawing showing a wastewater treatment device including a membrane bioreactor according to one embodiment of the present invention.

[0116] FIG. 5a illustrates the overall process of the wastewater treatment device of the present invention, and FIG. 5b and FIG. 5c show a plan view and a cross-sectional view of the bioreactor upstream of the membrane bioreactor.

[0117] Referring to FIG. 5, the wastewater treatment device (500) includes an anaerobic tank (510), a swing reactor (520), a simultaneous nitrification and denitrification reactor (Sim-NDN) reactor (530), a granule separation tank (540), an inclined plate section (545), and a membrane biological reactor (550).

[0118] Here, the anaerobic tank (510), swing reactor (520), simultaneous nitrification / denitrification (Sim-NDN) reactor (530), and granule separation tank (540) correspond to biological reactors that perform the growth of granule sludge and the decomposition of contaminants, and can perform the removal of organic matter, nitrogen, and phosphorus in wastewater. Each unit process constituting the biological reactor is organically connected so that the AGS-MBR process is efficiently performed in the downstream membrane biological reactor (550) and the granule sludge can be effectively operated throughout the entire process.

[0119] The anaerobic tank (510) receives wastewater and granule sludge to supply sufficient organic matter to the granules, thereby producing granule sludge, and discharges the granule sludge and wastewater after the reaction is completed to the swing reactor (520). The anaerobic tank (510) may include an internal stirring means (not shown) to supply organic matter to the granules.

[0120] The anaerobic tank (510) has a granule inlet (513) and a wastewater inlet (515) formed on one side, and receives granule sludge separated from the granule separation tank (540) at the rear through the granule inlet (513).

[0121] In particular, in one embodiment of the present invention, the wastewater treatment device (500) may have the anaerobic tank (510) divided into multiple zones.

[0122] For example, as illustrated in FIG. 5b, the anaerobic tank (510) can be divided into three zones and operated individually. In this case, each anaerobic tank (510a, 510b, 510c) may be individually equipped with a granule inlet (513), a wastewater inlet (515), and a stirring means. The first to third anaerobic tanks (510a, 510b, 510c), separated into three zones, are operated in parallel, and wastewater and granules are sequentially introduced, and the formation of granule sludge is performed according to a preset operating sequence.

[0123] The anaerobic tank (510) of the present invention is configured in an operating sequence to create a high organic matter loading rate and intermittent nutrient supply (Feast-Famine) condition necessary for the formation of granules. That is, a high organic matter / microorganism ratio (Food-to-Microorganism Ratio, F / M) is maintained to efficiently form granules, and organic matter from the incoming wastewater is supplied preferentially to the granules.

[0124] Referring to FIG. 5c, the granule inlet (513) and the wastewater inlet (515) formed in each anaerobic tank (510a, 510b, 510c) are formed at different heights on one side of each anaerobic tank (510a, 510b, 510c), and the wastewater inlet (515) is formed at the bottom of the anaerobic tank (510a, 510b, 510c) so that the fluid flow within the anaerobic tank (510a, 510b, 510c) becomes an upward flow. On the other hand, it is preferable that the granule inlet (513) be formed at an intermediate height of the anaerobic tank (510a, 510b, 510c), and it is preferable that a stirring means be provided between the granule inlet (513) and the wastewater inlet (515).

[0125] The first to third anaerobic tanks (510a, 510b, 510c) are started in sequence. In each unit anaerobic tank (510a, 510b, 510c), the reaction is carried out in a three-stage process of granule input, wastewater input, and stirring / discharge, and these three stages form one cycle.

[0126] Looking specifically at each operation step in the unit anaerobic tank (510), the unit anaerobic tank (510) receives granule sludge returned from the granule separation tank (540) through the granule inlet (513). The granule input step is performed for about 10 minutes, during which time the supply and stirring of wastewater are not performed. Among the input granule sludge, granules with relatively good settling properties settle to the bottom of the anaerobic tank (510), and granules with relatively poor settling properties are located at the top.

[0127] When the granules are added, the wastewater is introduced through the wastewater inlet (515). Since the wastewater inlet (515) is located at the bottom of the anaerobic tank (510), the introduced wastewater flows in while moving upward from the bottom of the anaerobic tank (510). The wastewater introduction step may take about 10 minutes, and no separate stirring is performed. During this process, the organic matter of the wastewater is preferentially supplied to the granule sludge that has already been introduced into the anaerobic tank (510) and settled at the bottom, thereby maintaining a Feast condition favorable for granule sludge formation.

[0128] While wastewater is supplied into the anaerobic tank (510), granule sludge with poor settling properties located at the top of the introduced granules is discharged to the downstream swing reactor (520). To this end, the upward flow velocity of the wastewater supplied into the anaerobic tank (510) is reduced so that the granule layer is not disturbed by the inflow of wastewater.

[0129] When the 10-minute wastewater input is completed, stirring is performed inside the anaerobic tank (510), and wastewater is input through the wastewater inlet (515) for an additional 10 minutes. During this process, the wastewater and granular sludge inside the anaerobic tank (510) are discharged to the downstream swing reactor (520).

[0130] Figure 6 illustrates the sequence in which the unit cycle consisting of granule input, wastewater input, stirring / discharge is operated in the first to third anaerobic tanks (510a, 510b, 510c) divided into three zones.

[0131] FIG. 6 is a diagram showing the operation cycle of an anaerobic tank in a wastewater treatment device according to one embodiment of the present invention.

[0132] Referring to FIG. 6, the processes of granule input (Phase 1), wastewater input (Phase 2), and stirring / discharge (Phase 3) proceed sequentially in the first anaerobic tank (510a). In each unit anaerobic tank (510a, 510b, 510c), granules are input at a 30-minute interval, wastewater is input at a 20-minute interval, and stirring is repeated at a 30-minute interval.

[0133] While the mixing / discharge process, in which wastewater is introduced and mixed in the first anaerobic tank (510a) (Phase 3), is being carried out, granules are introduced in the second anaerobic tank (510b) and the mixing / discharge process is being carried out sequentially, and while the mixing / discharge process is being carried out in the second anaerobic tank (510b), granules are introduced in the third anaerobic tank (510c) and sequential steps are carried out.

[0134] While granules are being fed into one of the unit anaerobic tanks (510a, 510b, 510c) (510a), no granules are being fed into the remaining anaerobic tanks (510b, 510c). Therefore, the entire amount of granule sludge returned from the granule separation tank (540) flows into the unit anaerobic tank (510). On the other hand, since the inflow of wastewater always occurs simultaneously in both unit anaerobic tanks, the flow rate of wastewater flowing into the unit anaerobic tanks (510a, 510b, 510c) corresponds to half of the total inflow rate.

[0135] As a result of operating multiple unit anaerobic tanks (510a, 510b, 510c) sequentially through the above operation process, each of the unit anaerobic tanks (510a, 510b, 510c) of the present invention can be operated under conditions substantially similar to a batch reactor, and as the individual unit anaerobic tanks (510a, 510b, 510c) are operated sequentially, the entire anaerobic tank (510) can be operated as a continuous process.

[0136] Referring again to FIG. 5, the Swing reactor (520) receives the granular sludge and wastewater from the anaerobic tank (510) after the reaction is completed, variably controls the internal environment to optimize the state of the granules or to stably form operating conditions in the subsequent simultaneous nitrification / denitrification reactor (530), performs additional reactions, and then discharges the entire amount of granular sludge and wastewater to the simultaneous nitrification / denitrification (Sim-NDN) reactor (530).

[0137] The swing reactor (520) can control the activity of the granule sludge by operating under anaerobic or aerobic conditions depending on the organic matter concentration of the incoming wastewater, and a portion of the granule sludge that has been rapidly settled with improved settling properties in the membrane bioreactor (550) is returned and used in the subsequent reaction.

[0138] For example, when there is sufficient organic matter in the incoming wastewater, the Swing reactor (520) is operated in an aerobic environment and rapidly removes excess residual organic matter so that the Famine state can be stably maintained for the granular sludge in the subsequent Sim-NDN reactor (530).

[0139] On the other hand, when the concentration of organic matter in the incoming wastewater is low, the reaction tank (520) can be operated in an anaerobic environment to allow sufficient dissolved organic matter to be absorbed by the granule sludge, thereby securing more time for the hydrolysis of organic matter.

[0140] Simultaneous nitrification / denitrification (Sim-NDN) reactor (530) receives sludge and wastewater that have passed through the Swing reactor (520), performs nitrification and denitrification reactions in the wastewater simultaneously to remove nitrogen, and then discharges the sludge and wastewater in which the reaction is completed to the Granule Separation Tank (540). At this time, the Simultaneous nitrification / denitrification (Sim-NDN) reactor (530) can receive a portion of the granule sludge that has been rapidly settled with improved settling properties from the membrane biological reactor (550) and utilize it for the reaction.

[0141] Simultaneous nitrification / denitrification (Sim-NDN) reactor (530) is maintained under aerobic conditions. The aerobic granular sludge (AGS) has an anoxic or anaerobic region inside and an aerobic region formed on the surface of the granules, so that a nitrification reaction is performed in the aerobic region on the surface of the granules, and a denitrification reaction is performed as the nitrate and nitrite generated therefrom diffuse into the anoxic region inside the granules.

[0142] The granule separation tank (540) receives the entire amount of sludge and wastewater from the Sim-NDN (sim-NDN) reaction tank (530) after the reaction is completed, performs solid-liquid separation to separate the granule sludge with excellent settling properties and the treated water, returns the separated granule sludge to the anaerobic tank (510), and discharges the treated water to the membrane biological reactor (550).

[0143] The granule separation tank (540) may include a separate separation means inside to separate granule sludge with excellent settling properties. The separation means may be any ordinary means capable of efficiently performing solid-liquid separation, and as an example, an inclined plate section (545) or a screen may be applied.

[0144] The membrane biological reactor (550) receives treated water in which granules with excellent settling properties have been separated in the first stage from the granule separation tank (540), and performs solid-liquid separation in the second stage through membrane filtration on the treated water to remove residual solids in the treated water, thereby producing treated water that meets target water quality standards and discharging it to the outside. In addition, granule sludge with relatively low settling properties contained in the treated water is separated by settling by applying shear force inside the reactor (550) to strengthen the granule structure and improve settling properties, and the finally settled granule sludge is returned to the shearing swing reactor (520) and / or simultaneous nitrification / denitrification (Sim-NDN) reactor (530).

[0145] The wastewater treatment device (500) of the present invention can reduce the concentration of sludge flowing into the membrane bioreactor (550) by providing a granule separation tank (540) upstream of the membrane bioreactor (550). As a result, the formation of a sludge cake layer in the membrane bioreactor (550) is minimized, and the flow rate returned from the membrane bioreactor (550) can be reduced, thereby reducing the amount of dissolved oxygen flowing into the upstream bioreactor.

[0146] Furthermore, when utilizing the existing secondary sedimentation tank as a membrane biological reactor (550), the existing equipment can be utilized to maximize shear force inside the reactor, thereby minimizing membrane fouling on the membrane surface, which can improve membrane filtration efficiency and maintenance efficiency, and there is an advantage that the sedimentation ability can be improved by additionally reinforcing the granular structure for granular sludge with relatively poor sedimentation ability.

[0147] The method for treating wastewater using the wastewater treatment device of the present invention is carried out in the following steps.

[0148] Wastewater is received and organic matter is decomposed in an anaerobic environment to induce the growth of granular sludge (S710).

[0149] The anaerobic tank (510) receives wastewater from the outside and receives granule sludge returned from the granule separation tank (540), and reacts the granule sludge with the wastewater in an anaerobic environment to promote the growth of the granules. To this end, the anaerobic tank (510) repeatedly performs a unit cycle consisting of (a) a granule input step; (b) a step of inputting only wastewater without stirring; and (c) a step of additionally inputting wastewater while stirring and discharging it to the downstream swing reaction tank (520).

[0150] For wastewater and granule sludge that have passed through an anaerobic environment, the activity of the granules is promoted by changing the environment to aerobic or anaerobic depending on the concentration of organic matter in the wastewater (S720).

[0151] Wastewater and granule sludge discharged from the anaerobic tank (510) are introduced into the swing reactor (520). The swing reactor (520) variably changes the process environment according to the concentration of organic matter in the wastewater introduced into the reactor for the formation of granules and the activation of granules in subsequent processes. That is, when the concentration of organic matter in the wastewater is excessively high, the swing reactor (520) is maintained in an aerobic environment to rapidly remove organic matter for the nitrification and denitrification reactions of the granule sludge at the downstream end. On the other hand, when the concentration of organic matter is low, the swing reactor (520) is operated in an anaerobic environment so that sufficient organic matter can be supplied to the granules, thereby securing the time required for the hydrolysis of organic matter.

[0152] Nitrification and denitrification reactions are performed by granular sludge with controlled activity to remove nitrogen from wastewater (S730).

[0153] Wastewater and granular sludge discharged from the swing reactor (520) are introduced into the simultaneous nitrification / denitrification (Sim-NDN) reactor (530), and nitrification and denitrification reactions are performed by the granular sludge.

[0154] The nitrogen-removed wastewater and granular sludge are separated into solid and liquid phases to separate granules with excellent settling properties from the wastewater, and the separated granules are returned to a stage to induce the growth of granular sludge (S740).

[0155] The granule separation tank (540) receives nitrogen-removed wastewater and granule sludge, separates them into granules with excellent settling properties and treated water, and the separated granules are returned to the anaerobic tank (510).

[0156] The above solid-liquid separated treated water flows into a membrane bioreactor (550), where residual solids in the treated water are further removed by membrane filtration, and is produced as final treated water and discharged to the outside (S750).

[0157] In the membrane bioreactor (550), shear force is generated internally by air supplied from the membrane filtration device (170), and granular sludge with low settling ability remaining in the wastewater is subjected to shear force in the membrane bioreactor (550), thereby strengthening the granular structure and forming granules with excellent settling ability. The granules with improved structure are settled and separated and returned to the swing reactor (520) and / or the simultaneous nitrification / denitrification reactor (530).

[0158] The wastewater treatment device and wastewater treatment method using the same according to the present invention can improve process operation efficiency by dividing the anaerobic tank into a plurality of unit anaerobic tanks (510a, 510b, 510c) and operating them sequentially. In addition, by forming operating conditions so that granules with excellent settling properties can preferentially come into contact with organic matter in the anaerobic tank, and by providing a swing reactor (520) at the downstream end so that process operation can be flexibly changed according to the characteristics of the granules, granule sludge can be stably formed and maintained within the treatment process.

[0159] The above description is merely an illustrative explanation of the technical concept of the present embodiment, and a person skilled in the art to which the present embodiment belongs would be able to make various modifications and variations within the scope of the essential characteristics of the present embodiment. Accordingly, the present embodiments are intended to explain, not limit, the technical concept of the present embodiment, and the scope of the technical concept of the present embodiment is not limited by these embodiments. The scope of protection of the present embodiment shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present embodiment.

[0160]

[0161] CROSS-REFERENCE TO RELATED APPLICATION

[0162]

[0163] If this patent application claims priority under Section 119(a) of the U.S. Patent Act (35 USC § 119(a)) to Korean Patent Application No. 10-2024-0154566 filed on November 4, 2024, all of the contents thereof shall be incorporated into this patent application by reference. Furthermore, if this patent application claims priority in countries other than the United States for the same reasons as above, all of the contents thereof shall be incorporated into this patent application by reference.

Claims

1. As a membrane bioreactor modified from an existing circular sedimentation tank for application in the aerobic granular sludge-membrane filtration (AGS-MBR) process, Circular reactor body; An inlet pipe vertically positioned in the center of the main body of the reactor above to supply sludge and treated water discharged from the biological reactor of the preceding section to the main body of the reactor above; A cylindrical feedwell disposed on the outer side of the inlet pipe and installed concentrically with the inlet pipe; A membrane filtration device positioned to be immersed inside the main body of the above-mentioned reaction vessel to perform solid-liquid separation; A membrane support frame provided at the top of the above-mentioned reaction vessel body and supporting the membrane filtration device while it is immersed inside the reaction vessel body; and It includes a partition wall installed between the above-mentioned membrane filtration device and the overflow weir of the above-mentioned reaction tank body, The above-mentioned partition wall is characterized by blocking solids with poor settling properties from being discharged through the overflow weir by the upward flow generated by the membrane filtration device, in an improved type of conventional sedimentation tank membrane biological reactor.

2. In Paragraph 1, The above feedwell changes the flow of treated water and sludge entering through the inlet pipe downward so that the treated water and sludge are supplied into the main body of the reaction tank, A membrane biological reactor of the improved type of conventional sedimentation tank, characterized in that the uppermost part of the feedwell is located below the effective water level of the main body of the reactor, and as the treated water and sludge transferred to the upper part of the reactor by the upward flow formed by the membrane filtration device flow into the upper part of the feedwell and move downward, a longitudinal shear force is induced to be generated inside the reactor.

3. In Paragraph 2, The above feedwell is, It further includes an inclined plate section having a plurality of inclined pieces arranged inside, and The plurality of inclined pieces are installed so as to be inclined and distributed to connect the inlet pipe and the feed well, and have an inclination within a preset range. A conventional sedimentation tank improved membrane bioreactor characterized in that the fluid flow discharged from the lower part of the feedwell is discharged into the reactor while rotating in one direction along the inclined direction of the inclined plate.

4. In Paragraph 1, The above bulkhead is, The uppermost part is formed higher than the upper part of the overflow weir, and A membrane bioreactor of the improved type of conventional sedimentation tank, characterized in that the bottom is formed to be located lower than the bottom of the membrane filtration device.

5. In Paragraph 1, The above-mentioned separator support frame is, A conventional sedimentation tank improved type membrane biological reactor characterized by having one end fixed to an overflow weir formed on the side wall of the main body of the reactor and the other end fixed to the outer circumference of the feed well, connecting the center of the main body of the reactor and the side wall, and having at least two or more provided in the main body of the reactor.

6. In Paragraph 1, The above membrane bioreactor is, It further includes a maintenance walkway installed to cross the top of the main body of the reactor and utilized as a worker's passageway, A membrane bioreactor of the improved type of conventional sedimentation tank, characterized in that the above maintenance walkway is rotatable with respect to the center of the main body of the reactor.

7. In Paragraph 6, The above-mentioned separator support frame is, An upper support frame having one side connected to the lower part of the maintenance walkway and the other side extended toward the main body of the reaction vessel to support the membrane filtration device, and It includes a lower support frame that extends from the lower part of the membrane filtration device toward the bottom of the reaction tank body and has a sludge collection device connected to its end for collecting sludge settled on the bottom of the reaction tank body. A membrane biological reactor of the improved type of conventional sedimentation tank, characterized in that as the above maintenance walkway rotates, the membrane filtration device fixed to the above membrane support frame rotates around the rotation axis at the center of the main body of the reactor.

8. A wastewater treatment device operated by an aerobic granular sludge-membrane filtration process including the membrane biological reactor of Paragraph 1, comprising: An anaerobic tank that receives wastewater, induces the growth of granular sludge, and decomposes organic matter; A simultaneous nitrification / denitrification reactor that receives granular sludge grown in the above anaerobic tank and wastewater, and removes nitrogen from the wastewater using the granular sludge; A granule separation tank that receives nitrogen-removed wastewater and granule sludge and separates them into granule sludge and supernatant through solid-liquid separation; and A membrane bioreactor that receives the supernatant separated from the above-mentioned granule separation tank, filters solids secondarily, and improves the settling properties of granule sludge in the supernatant. Wastewater treatment device including 9. In Paragraph 8, A swing reactor is further included between the above anaerobic tank and the simultaneous nitrification / denitrification reactor, and A wastewater treatment device characterized by the above-mentioned swing reactor receiving sludge and wastewater that have passed through an anaerobic tank, and operating in an aerobic or anaerobic manner depending on the concentration of organic matter in the wastewater.

10. In Paragraph 8, The granular sludge separated from the solid-liquid state in the above granular separation tank is, A wastewater treatment device characterized by being returned to the above-mentioned anaerobic tank.

11. In Paragraph 9, Granular sludge with improved settling properties, subjected to shear force in the above-mentioned membrane bioreactor, settles to the bottom of the above-mentioned membrane bioreactor, and A wastewater treatment device characterized by the fact that the settled granular sludge is returned to the swing reactor or the simultaneous nitrification / denitrification reactor.

12. In Paragraph 8, The above anaerobic tank is, The interior is divided into multiple zones to consist of multiple unit anaerobic tanks, and Each unit anaerobic tank is, A stage where only granular sludge is input without the input of sewage or wastewater; A stage where only sewage and wastewater are injected; and A wastewater treatment device characterized by a step in which stirring is performed, wastewater is continuously fed in, and wastewater and granules in the anaerobic tank are discharged into a swing reactor, which is configured as a single cycle and operated repeatedly.

13. In Paragraph 12, The above anaerobic tank consists of three unit anaerobic tanks, and A wastewater treatment device characterized by the fact that while stirring and wastewater inflow are performed in the first anaerobic tank, granule input is initiated in the second anaerobic tank and the process of wastewater input and stirring is performed sequentially, and while stirring and wastewater inflow are performed in the second anaerobic tank, granule input is initiated in the third anaerobic tank and each unit anaerobic tank is operated sequentially.

14. A method for treating wastewater using an aerobic granular sludge-membrane filtration process including the membrane biological reactor of Claim 1, wherein A step of receiving wastewater, decomposing organic matter in an anaerobic environment, and inducing the growth of granular sludge; A step of controlling the activity of granule sludge by varying the environment to aerobic or anaerobic depending on the organic matter concentration in the wastewater and granule sludge that have passed through the above anaerobic environment; A step in which nitrification and denitrification reactions are performed by the above-mentioned activity-controlled granular sludge to remove nitrogen from wastewater; A step of separating the nitrogen-removed wastewater and granular sludge into solid and liquid phases to separate them into granular sludge and treated water, and returning the separated granular sludge to a step for inducing the growth of the granular sludge; and A step in which the above solid-liquid separated treated water is introduced into the above membrane biological reactor, and residual solids in the treated water are further removed by membrane filtration and discharged as treated water. A wastewater treatment method comprising an aerobic granular sludge-membrane filtration process including 15. In Claim 14, The above membrane bioreactor applies shear force to granular sludge with relatively poor settling properties that was not separated in the above granular separation tank, thereby improving the settling properties of the granular sludge, and A wastewater treatment method comprising an aerobic granular sludge-membrane filtration process, characterized in that granular sludge, which has improved settling properties by receiving shear force in the above-mentioned membrane biological reactor, settles to the bottom of the membrane biological reactor and is returned to a step of controlling the activity of the granular sludge and / or a step of removing nitrogen by the granular sludge.

16. In Claim 14, The step of inducing the growth of the above granular sludge is performed in an anaerobic tank, wherein The above anaerobic tank is, A stage where only granular sludge is input without the input of sewage or wastewater; A stage where only sewage and wastewater are injected; and A wastewater treatment method comprising an aerobic granule sludge-membrane filtration process characterized by a step in which stirring is performed, wastewater is continuously fed in, and wastewater and granules in the anaerobic tank are discharged to a downstream process, which is configured as a single cycle and operated repeatedly.

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