JP2018043214A - Sewage treatment equipment and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sewage treatment equipment capable of ensuring a stable upward flow even when a membrane separation device is installed in a compact space and capable of reducing operation cost.SOLUTION: Sewage treatment equipment 10 comprises: an anoxic tank 2 which is maintained in a dissolved oxygen-free state and performs denitrification treatment for reducing at least nitrate nitrogen contained in water to be treated; an aerobic tank 4 which is maintained in an aerobic state and performs nitrification treatment for nitrifying ammonia nitrogen contained in the water to be treated flowing in from the anoxic tank 2; and a plurality of membrane separation devices 7 which are disposed so as to be immersed in the water to be treated having been subjected to the nitrification treatment and performs solid-liquid separation treatment for obtaining permeated water from the water to be treated. A trough 8 extending toward the anoxic tank is disposed in a space above each membrane separation device, and concentrated water after the solid-liquid separation treatment is overflowed into the trough 8 by an upward flow of the water to be treated caused by air diffused from a diffusing mechanism 7A provided in the membrane separation device 7 and returned to the anoxic tank 2.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sewage treatment facility and a sewage treatment method for purifying organic wastewater such as sewage sludge and wastewater generated in a food factory.

  Patent Document 1 includes an anaerobic tank (anoxic tank) for anaerobically treating the liquid to be treated, an aeration tank (aerobic tank) for aeration of the liquid to be treated, and a membrane separation device for obtaining a permeate from the liquid to be treated. A membrane separation activated sludge treatment apparatus including a membrane separation tank disposed is disclosed.

  Excess sludge in the membrane separation tank is drawn out of the tank, and a part thereof is circulated and supplied to the anaerobic tank (anoxic tank) via a pump. This circulating sludge amount is set to about 4Q with respect to the inflow sludge amount Q to the anaerobic tank (anoxic tank).

  In Patent Document 2, an anaerobic tank into which raw water is introduced, an anaerobic tank connected to a downstream side of the anaerobic tank via a partition wall, and denitrifying the water to be treated by anaerobic microorganisms; An aerobic tank that is disposed through a partition wall and nitrifies ammonia contained in the treated water flowing out of the anaerobic tank with an aerobic microorganism, and a part of the treated water that has been nitrified in the aerobic tank into the anoxic tank Disclosed is a sewage treatment facility equipped with an air lift pump device for returning.

  The aerobic tank is divided into a first area where an air diffusion mechanism is installed and a second area where a membrane separation device is arranged via a separation wall, and the water to be treated flowing out of the anoxic tank is the first area. The air lift pump device is installed on the downstream side of the second region which is aerobically treated and functions as a membrane separation tank.

  In Patent Document 3, a filtration membrane unit that is immersed in a liquid pool of a liquid to be treated to generate a permeate from the liquid to be treated, a rising pipe that accommodates the filtration membrane unit, and a filter membrane unit An aeration unit that is disposed below and supplies scrubbing air to the filtration membrane unit, and a liquid to be processed that rises in the riser pipe together with the scrubbing air connected to the upper part of the riser pipe is transferred to the side. An apparatus for both filtration and air lift, including a transfer path for performing the above-described process, is disclosed.

JP 2013-22549 A JP 2011-1918 A JP 2014-57906 A

  FIG. 2 shows an example of a membrane separation device immersed in a membrane separation tank. In the membrane separation apparatus, a large number of plate-like membrane elements are arranged in a membrane case 71 having upper and lower openings so that each membrane surface has a vertical posture, and further, the membrane case 71 Is provided with an air diffusion mechanism 7A.

  The diffuser mechanism 7A includes a diffuser tube 13 having a plurality of diffuser holes, and is connected to an air supply source such as a blower B or a compressor installed outside the tank via an diffuser header 14 connected to the diffuser tube 13. Has been.

  The upward flow of the water to be treated is formed by the air lift effect of the bubbles released from the air diffusion mechanism 7A, and the fouling causative substances attached to the membrane surface of each membrane element are removed by the upward flow flowing along the membrane surface. The

  In order to efficiently remove the fouling-causing substances, it is necessary to provide a transmembrane flow rate above a certain level according to the sludge properties and the operation flux (permeated water amount per unit area). There was a need to form a stable flow through the top opening.

  Therefore, conventionally, an appropriate flow around the membrane separation device is obtained so that a smooth swirling flow in which the upward flow flowing from the lower opening to the upper opening of the membrane case 71 becomes a downward flow outside the membrane case 71 can be obtained. It was necessary to secure a space of a proper size.

  However, there is a problem that the membrane separation tank in which the membrane separation apparatus is installed becomes large for that purpose, and the equipment cost increases. Further, the upward flow of the water to be treated flowing from the lower opening to the upper opening of the membrane case 71 suppresses the contamination of the membrane surface, but the downward flow required for forming the swirl flow is a direct added value. There is also a problem that power consumed in the air diffusion mechanism is wasted.

  According to the combined filtration and air lift device described in Patent Document 3, filtration of the liquid to be treated, cleaning of the filtration membrane unit, and transfer of the liquid to be treated can be realized with a single device, and less power consumption. It becomes possible to transfer the liquid to be processed.

  However, among the plurality of filtration devices immersed in the membrane separation tank, the filtration devices other than the filtration and air lift combined device installed in the vicinity of the reflux path are smoothly circulated similarly to Patent Documents 1 and 2. Therefore, there is a problem that it is necessary to secure an appropriate size space around the filtration device, and a large capacity membrane separation tank is required.

  Also, since the functions of the filtration and air lift combined device and the filtration device other than the filtration and air lift combined device are different, the amount of air diffused is different, and the filtration and air lift combined device and the filtration device other than the filtration and air lift combined device This may cause an imbalance in the permeation performance of the membrane.

  Furthermore, it is necessary to provide a reflux path adjacent to the anaerobic tank and the oxygen-free tank, and there is a problem that a large site is required to install the equipment.

  In view of the above-described problems, an object of the present invention is to provide a sewage treatment facility and a sewage treatment method capable of ensuring a stable upward flow even when a membrane separation apparatus is installed in a compact space, and reducing operating costs. It is in.

  In order to achieve the above-mentioned object, the first characteristic configuration of the sewage treatment facility according to the present invention is, as described in claim 1 of the claims, maintained at a state in which no dissolved oxygen is present and at least water to be treated. An oxygen-free tank in which denitrification treatment is performed to reduce nitrate nitrogen contained in the water, and a nitrification treatment in which ammonia nitrogen contained in the water to be treated that is maintained in an aerobic state and flows from the oxygen-free tank is nitrified. A sewage treatment facility comprising an aerobic tank and a plurality of membrane separation devices that are immersed in the treated water that has been subjected to the nitrification treatment and that perform a solid-liquid separation process for obtaining permeated water from the treated water. The trough extending toward the oxygen-free tank is disposed in the upper space of each membrane separation device, and the above-described flow of the water to be treated caused by the diffusion from the diffusion mechanism provided in the membrane separation device Concentrated water after solid-liquid separation treatment Serial by overflow into the trough in that it is configured to return to the anoxic tank.

  The to-be-treated water that flows upward from the lower side of the membrane separation device by the upward flow generated by the air lift effect caused by the air bubbles released from the air diffusion mechanism, that is, the concentrated water after membrane filtration is provided in the trough provided above the membrane separation device. It is returned to the anoxic tank via the trough and denitrified. Therefore, it is not necessary to provide a separate pump mechanism for returning the concentrated water to the oxygen-free tank, and the operating cost spent on power can be reduced accordingly. In addition, it is not necessary to secure an extra space for forming a swirling flow in which the water to be treated that has flowed upward from the membrane separator descends and circulates around the membrane separator, and the installation space for the membrane separator is eliminated. It becomes possible to reduce the equipment cost. For example, even if a membrane separation device is immersed in a section of an aerobic tank, the movement of bubbles released from the air diffuser installed for aerobic treatment is not disturbed, and the device is more compact. Sewage treatment facilities can be constructed. Furthermore, since it is not necessary to form a swirling flow, it is not necessary to set a large amount of air diffusion, and it is possible to secure a sufficient contact time between the gentle upward flow and the membrane surface, thereby stressing the membrane surface. A sufficient cleaning effect can be obtained without imparting.

  In addition to the first feature configuration described above, the second feature configuration includes a pair of the above-described membrane separation devices arranged in a straight line in plan view. The troughs are located opposite each other.

  When the upward flow of the water to be treated generated by the air diffused from the air diffusion mechanism turns into a horizontal flow intersecting the arrangement direction in the upper space of each membrane separation device arranged in a straight line, each membrane separation device in plan view It flows into a pair of troughs arranged in the upper space of each membrane separation device so as to sandwich the membrane, and the concentrated water after solid-liquid separation processing in each membrane separation device efficiently flows A trough can be realized.

  In the third feature configuration, in addition to the first or second feature configuration described above, an oxygen-free tank is disposed on both sides of the aerobic tank, and the solid liquid The trough is shared so that the concentrated water after separation treatment is returned to each oxygen-free tank.

  Water to be treated that has been nitrified in an aerobic tank is subjected to solid-liquid separation by a membrane separation device, and permeated water is taken out. At this time, the concentrated water that has not been filtered by the upward flow generated by the air lift effect caused by the bubbles released from the air diffuser flows into the common trough and returns to each of the anaerobic tanks arranged on both sides of the aerobic tank. The denitrification treatment will be carried out and a compact sewage treatment facility can be constructed.

  In the fourth feature configuration, as described in claim 4, in addition to any one of the first to third feature configurations described above, the aerobic tank extends in the width direction intersecting the flow of water to be treated. The membrane separator is divided into a plurality of regions along the boundary, and the membrane separation device is disposed at the boundary between the regions.

  The water to be treated is filtered by the membrane separation device arranged at the boundary of each region of the aerobic tank divided into a plurality of regions, and the concentrated water is passed through the trough arranged in the upper space of each membrane separation device. As a result, the flow of water to be treated does not occur so that the upward flow generated in each membrane separation device circulates by turning to the downward flow around it. Therefore, it becomes possible to construct a compact sewage treatment facility that can stably perform aerobic treatment without disturbing the flow of water to be treated in each region.

  In the fifth feature configuration, as described in claim 5, in addition to any of the first to third feature configurations described above, the membrane separation tank into which the water to be treated into which the nitrification treatment has been performed flows. Is provided, and the membrane separation device is immersed in the membrane separation tank.

  The aerobic tank and the membrane separation tank are partitioned so that the water to be treated that has been subjected to nitrification in the aerobic tank flows into the membrane separation tank in which the membrane separation device is immersed and separated. A trough extending from the upper space of the membrane separation device provided in the separation tank toward the oxygen-free tank may be disposed. Even in such a configuration, it is not necessary to form a circulation flow of the water to be treated, so that a compact membrane separation tank can be obtained.

  The first characteristic configuration of the sewage treatment method according to the present invention is to reduce at least nitrate nitrogen contained in water to be treated in an oxygen-free tank maintained in a state in which no dissolved oxygen exists, as described in claim 6. Denitrification treatment, nitrification treatment for nitrifying ammonia nitrogen contained in water to be treated flowing from the oxygen-free tank in an aerobic tank maintained in an aerobic state, and immersion arrangement in the nitrification treated water And a solid-liquid separation method for obtaining permeate from treated water by a plurality of membrane separation devices, which is caused by aeration from an aeration mechanism provided below each membrane separation device. By the upward flow of the water to be treated, the trough arranged to extend toward the oxygen-free tank in the upper space of each membrane separation apparatus overflows the concentrated water after the solid-liquid separation treatment, and It is in the point of returning to the anoxic tank.

  As described above, according to the present invention, it is possible to provide a sewage treatment facility and a sewage treatment method capable of ensuring a stable upward flow even when a membrane separation device is installed in a compact space, and reducing the operating cost. It became so.

(A) is a plan view of a sewage treatment facility, (b) is a cross-sectional view taken along line AA of (a), and (c) is a cross-sectional view taken along line BB of (a). Illustration of membrane separator Illustration of membrane element (A) is a plan view of a sewage treatment facility showing a first alternative embodiment, (b) is a plan view of a sewage treatment facility showing a second alternative example, and (c) is a sewage treatment showing a third alternative example. Plan of equipment The top view of the sewage treatment facility which shows a 4th another Example Sectional drawing of the sewage treatment equipment which respond | corresponds to FIG.1 (c) and shows a 5th another Example

Hereinafter, the sewage treatment facility according to the present invention will be described.
1A, 1B, and 1C show a sewage treatment facility 10 that purifies organic wastewater.

  The sewage treatment facility 10 includes an oxygen-free tank 2 in which denitrification treatment is performed to reduce nitrate nitrogen contained in water to be treated, and at least a diffuser 4A installed at the bottom. The aerobic tank 4 in which nitrification treatment is performed to nitrify ammonia nitrogen contained in the water to be treated which has been maintained in an aerobic state and has flowed in from the anoxic tank 2 and the water to be treated in which the nitrification treatment has been performed. And a plurality of membrane separation devices 7 for performing solid-liquid separation processing for obtaining permeated water from the water to be treated.

  The anaerobic tank 2 and the aerobic tank 4 are composed of a concrete frame, and are partitioned by a partition wall 3. A part of the lower end of the partition wall 3 is opened, and the water to be treated which is raw water flowing into the anoxic tank 2 flows into the aerobic tank 4 together with the activated sludge and is subjected to aerobic treatment.

  As shown in FIG. 2, the membrane separation device 7 has 100 plate-like membrane elements 7 </ b> B inside a membrane case 71 that is open at the top and bottom so that each membrane surface is in a vertical posture and about 6 mm to 10 mm. (In this embodiment, 8 mm) are arranged at regular intervals, and further, an air diffusion mechanism 7A is provided below the membrane case 71.

  The diffuser mechanism 7A includes a diffuser tube 13 having a plurality of diffuser holes, and is connected to an air supply source such as a blower B or a compressor installed outside the tank via an diffuser header 14 connected to the diffuser tube 13. Has been. In this embodiment, the blower B is used as an air supply source.

  A pump P1 as a suction mechanism installed outside the tank is connected to the membrane element 7B via a water collecting pipe 17, and the water to be treated in the tank is suction filtered so as to pass through the membrane surface of the membrane element 7B.

  As shown in FIG. 3, the membrane element 7 </ b> B has separation membranes 12 disposed on both front and back surfaces of a resin membrane support 10 having a length of 1000 mm × width of 490 mm via spacers 11. 13 is bonded to the membrane support 10 by ultrasonic waves or heat, or is bonded using an adhesive or the like.

  The separation membrane 12 is a microporous membrane having an average pore diameter of about 0.2 μm, and is an organic filtration membrane in which a nonwoven fabric is coated and impregnated with a porous resin. The membrane element 7B is not limited to such a configuration, and the separation membrane 12 is disposed so as to be wound on both the front and back surfaces of the membrane support 10, and the end of the separation membrane 12 is bonded or welded. Also good.

  A plurality of groove portions 10b having a depth of about 2 mm and a width of about 2 mm are formed along the longitudinal direction on the surface of the membrane support 10, and a horizontal groove portion 10c that communicates with each groove portion 10b is formed at the upper end portion thereof. Horizontal groove portions 10c formed on both front and back surfaces are communicated with each other via a communication hole 10d and communicated with a nozzle 10a formed on the upper edge portion of the membrane support 10.

  Each nozzle 10a is connected to a water collecting pipe 17 through a tube 16, and a pump P1 as a suction mechanism is connected to the water collecting pipe 17 so that permeated water sucked by the pump P1 is transferred to the treated water tank 8. It is configured (see FIG. 2).

  By operating the air diffusion mechanism 7A of the membrane separation device 7 as described above, an upward flow of mixed water of the water to be treated and the activated sludge is formed in the gap of the membrane element 7B from the lower side to the upper side. Fouling substances and contaminants deposited on the membrane surface can be removed, and permeated water in which the water to be treated has permeated the separation membrane 12 can be obtained by operating the suction mechanism P1.

Returning to FIGS. 1A, 1B, and 1C, the description will be continued.
In the aerobic tank 4, a plurality of the above-described membrane separation devices 7 are immersed in the central direction in the width direction intersecting the flow direction of the water to be treated from the anaerobic tank 2 to the aerobic tank 4 along the flow direction. The membrane separation tank 6 is functionally formed by the region where the membrane separation device 7 is immersed. The section in which the membrane separation device 7 is immersed is not limited to the central region in the width direction, but may be one section of the aerobic tank 4.

  Ammonia nitrogen contained in the water to be treated flowing into the aerobic tank 4 is nitrified to nitrite nitrogen and nitrate nitrogen by aerobic microorganisms under the aeration from the aeration device 4A provided in the aerobic tank 4 After that, the membrane separation device 7 performs solid-liquid separation into permeated water and activated sludge, and the treated water that has passed through the membrane separation device 7 is discharged into the river.

  In plan view, a pair of troughs 8 extending toward the anaerobic tank 2 are opposed to each other in the upper space of each membrane separation device 7 so as to sandwich each membrane separation device 7 arranged linearly.

  When the upward flow of the water to be treated generated by the air diffused from the air diffuser mechanism 7A turns into a horizontal flow intersecting the arrangement direction in the upper space of the membrane separation devices 7 arranged linearly in plan view, It flows into a pair of troughs 8 arranged in a space above each membrane separation device 7 so as to sandwich each membrane separation device 7 in plan view. The treated water flowing into the trough 8 is mainly concentrated water after being subjected to solid-liquid separation processing in each membrane separation device 7.

  The trough 8 is composed of a concrete structure having a J-shaped cross section, and the upper end of the rising portion of the trough 8 which is a surface facing the membrane separation device 7 is aerobic tank 4 due to the upward flow of the water to be treated. The water level is slightly higher than the water level. In addition, a passage 9 that is also made of a concrete structure is disposed above the trough 8, and safety fences 9 </ b> A are disposed on both sides of the passage 9.

  The water to be treated that flows from the lower side to the upper side of the membrane separator 7 due to the upward flow generated by the air lift effect caused by the air bubbles released from the air diffusion mechanism 7A of the membrane separator 7 overflows the upper end of the rising portion of the trough 8. It flows into the trough 8, flows through the trough 8, and is returned to the anoxic tank 2.

  Nitrate nitrogen and / or nitrite nitrogen contained in the treated water returned to the anoxic tank 2 together with the activated sludge is reduced by the denitrifying microorganisms in the anoxic tank 2 and removed as nitrogen gas, that is, denitrifying treatment Is done. It is preferable that the end of the trough 8 is set to be positioned upstream of the anaerobic tank 2 so that sufficient denitrification treatment is performed in the anaerobic tank 2.

  If comprised in this way, it is not necessary to provide the separate pump mechanism for returning concentrated water to the anaerobic tank 2, and the operating cost spent for motive power can be reduced that much.

  In addition, it is not necessary to secure an extra space for forming a swirling flow in which the water to be treated that has flowed upward from the membrane separation device 7 descends and circulates around the membrane separation device 7. The installation space can be made compact, and the equipment cost can be reduced.

  For example, even if the membrane separation device 7 is immersed in a section of the aerobic tank 4, the movement of bubbles released from the aeration device 4A for aerobic treatment is not disturbed, and it is even more compact. Sewage treatment facilities can be constructed.

  Furthermore, since it is not necessary to form a swirling flow, it is not necessary to set a large amount of air diffusion, and it is possible to secure a sufficient contact time between the gentle upward flow and the membrane surface, thereby stressing the membrane surface. A sufficient cleaning effect can be obtained without imparting.

Hereinafter, another embodiment will be described.
In the above-described embodiment, the biological treatment tank has been described with the anoxic tank 2, the aerobic tank 4, and the membrane separation tank 6 provided in the aerobic tank 4, but as shown in FIG. In addition, the anaerobic tank 1 may be provided upstream of the anaerobic tank 2 so that the BOD component contained in the raw water is taken in by anaerobic microorganisms under anaerobic conditions.

  In this case, the phosphorus compound is hydrolyzed in the anaerobic tank 1 and released into the liquid as normal phosphoric acid, and the normal phosphoric acid in the water to be treated is taken into the sludge as polyphosphoric acid in the aerobic tank 4, and phosphorus is added together with the excess sludge. Can be removed. In addition, you may comprise so that a part of concentrated water returned from the trough 8 may be returned to the anaerobic tank 1 as shown with a broken line in Fig.4 (a).

  As shown in FIG. 4 (b), anaerobic tanks 2, 2 are arranged on both sides of the aerobic tank 4. The part may be configured to be returned.

  The water to be treated that has been nitrified in the aerobic tank 4 is subjected to solid-liquid separation by a membrane separation device 7 that is immersed in a section of the aerobic tank 4. At that time, the upward flow of the water to be treated flowing into the membrane separation device 7 flows into the trough 8 and is returned to each of the anoxic tanks 2 and 2 disposed on both sides of the aerobic tank 4 for denitrification treatment. A compact sewage treatment facility 10 can be constructed.

  As shown in FIG. 4 (c), the aerobic tank 4 is separated from the aerobic tank 4, and a membrane separation tank 6 into which water to be treated that has been subjected to nitrification treatment flows is configured. The separation device 7 may be immersed and the water to be treated may be returned to the anoxic tank 2 along with the activated sludge through the trough 8 similar to that described above.

  A trough 8 extending from the upper space of the membrane separation device 7 provided in the membrane separation tank 6 toward the anoxic tank 2 may be arranged. Even in such a configuration, it is not necessary to form a circulation flow of the water to be treated, so that a compact membrane separation tank can be obtained.

  As shown in FIG. 5, the aerobic tank 4 may be divided into a plurality of regions along the width direction intersecting the flow of the water to be treated, and the membrane separation device 7 may be disposed at the boundary of each region.

  The treated water is filtered by the membrane separation device 7 arranged at the boundary of each region of the aerobic tank 4 divided into a plurality of regions, and the concentrated water is passed through the trough 8 arranged in the upper space of each membrane separation device 7. As a result of returning the water to the anaerobic tank 2, there is no large flow of water to be treated such that the upward flow generated in each membrane separation device 7 turns around and circulates downward. Therefore, it becomes possible to construct a compact sewage treatment facility that can stably perform aerobic treatment without disturbing the flow of water to be treated in each region.

  As shown in FIG. 6, the trough 8 is composed of a concrete structure having a J-shaped cross section, and a perforated plate such as a punching metal on the surface facing the membrane separation device 7 in the rising portion of the trough 8. 8A may be arranged.

  The perforated plate 8A is arranged at a position corresponding to the water level of the membrane separation tank 6 slightly rising from the water level of the aerobic tank 4 due to the upward flow of the water to be treated, and the concentrated water is supplied to the trough 8 from the hole of the perforated plate 8A. It may be configured such that it flows in, flows through the trough 8, and is returned to the anoxic tank 2.

  The sewage treatment facility 10 having a mode in which the configurations shown in FIGS. 1, 4 (a), (b), (c), FIG. 5, and FIG. 6 described above are appropriately combined may be constructed.

  In the above-described embodiment, the example in which the pair of troughs 8 are opposed to each other so as to sandwich the membrane separation devices 7 arranged in a straight line in plan view is described. However, the membrane separation devices 7 are not necessarily sandwiched. It is not necessary that the pair of troughs 8 is provided, and it is only necessary that the troughs 8 are provided so that the upward flow inside the membrane separation device 7 flows. For example, in the case of the membrane separation device 7 arranged close to the wall surface, a single trough may be installed on the side separated from the wall surface in the space above the membrane separation device 7.

  In the above-described embodiment, the example in which the plurality of membrane separation devices 7 are arranged in a straight line and the linear trough 8 is arranged along the arrangement direction of the membrane separation device 7 has been described. However, the trough 8 has a plurality of membranes. It only needs to be arranged along the separation device 7 and does not necessarily have to be arranged linearly.

  In the embodiment described above, an example in which a plurality of membrane separation devices 7 are provided and troughs are arranged along the arrangement direction of the membrane separation devices 7 has been described. For example, a plurality of membrane elements are accommodated in a single casing. The present invention can be applied to a single membrane separator 7 as long as it is a large membrane separator.

  By such a sewage treatment facility 10, a denitrification treatment that reduces at least nitrate nitrogen contained in the water to be treated in an anaerobic tank that is maintained in a state in which no dissolved oxygen is present, and aerobic that is maintained in an aerobic state. The permeated water is obtained from the water to be treated by nitrification treatment for nitrifying ammonia nitrogen contained in the water to be treated which flows from the oxygen-free tank in the tank, and a plurality of membrane separation devices immersed in the water to be treated for nitrification. A sewage treatment method for performing a solid-liquid separation process, wherein an upper space of each membrane separation device is caused by an upward flow of water to be treated generated by aeration from an aeration mechanism provided below each membrane separation device. Then, a sewage treatment method is performed in which the trough disposed so as to extend toward the anaerobic tank overflows the concentrated water after the solid-liquid separation treatment and returns it to the anoxic tank.

  The sewage treatment facility according to the present invention can be used for the treatment of various organic effluents such as sewage sludge and food factory effluent. When applied to the treatment of sewage sludge, the raw water may not be immediately put into the biological treatment tank, but a pretreatment facility and a flow rate adjustment tank may be provided in the previous stage. The pretreatment equipment is provided with a bar screen that removes contaminants mixed in the raw water, and the treated water from which the contaminants have been removed by the bar screen etc. is temporarily stored in the flow adjustment tank, and then fixed from the flow adjustment tank. You may comprise so that the to-be-processed water of a flow volume may be stably supplied to a biological treatment tank.

  The above-described embodiment is one aspect of the present invention, and the present invention is not limited by the description. Specific configurations and control aspects of each part can be appropriately changed and designed within the scope of the effects of the present invention. Needless to say.

2: Anoxic tank 4: Aerobic tank 6: Membrane separation tank 7: Membrane separation device 8: Trough

Claims (6)

An anaerobic tank in which a denitrification treatment is performed to reduce nitrate nitrogen contained in at least water to be treated while maintaining no dissolved oxygen,
An aerobic tank that is maintained in an aerobic state and is subjected to a nitrification treatment that nitrifies ammoniacal nitrogen contained in the water to be treated flowing from the anoxic tank;
A plurality of membrane separation devices in which solid-liquid separation processing is performed so as to be immersed in the water to be treated that has undergone the nitrification treatment to obtain permeated water from the water to be treated;
A sewage treatment facility comprising:
A trough extending toward the anaerobic tank is disposed in the upper space of each membrane separation device, and the solid liquid is caused by the upward flow of the water to be treated generated by the diffusion from the diffusion mechanism provided in the membrane separation device. A sewage treatment facility configured to allow the concentrated water after separation to overflow into the trough and return to the oxygen-free tank.   The sewage treatment facility according to claim 1, wherein the pair of troughs are opposed to each other so as to sandwich the membrane separation devices arranged in a straight line when seen in a plan view.   The oxygen-free tank is arrange | positioned on both sides on both sides of the aerobic tank, and the trough is shared so that the concentrated water after the solid-liquid separation treatment is returned to each oxygen-free tank. Sewage treatment equipment.   The sewage according to any one of claims 1 to 3, wherein the aerobic tank is divided into a plurality of regions along a width direction intersecting a flow of water to be treated, and the membrane separation device is disposed at a boundary between the regions. Processing equipment.   The sewage treatment facility according to any one of claims 1 to 3, wherein a membrane separation tank into which treated water that has undergone the nitrification treatment flows is provided, and the membrane separation device is immersed in the membrane separation tank. A denitrification treatment that reduces at least nitrate nitrogen contained in the water to be treated in an oxygen-free tank maintained in a state in which no dissolved oxygen exists;
A nitrification treatment for nitrifying ammonia nitrogen contained in the water to be treated flowing from the anoxic tank in an aerobic tank maintained in an aerobic state;
A solid-liquid separation process for obtaining permeated water from the water to be treated by a plurality of membrane separation devices that are immersed in the water to be treated that has been subjected to nitrification;
A sewage treatment method for performing
Arranged so as to extend toward the oxygen-free tank in the upper space of each membrane separation device by the upward flow of the water to be treated generated by the diffusion from the diffusion mechanism provided below each membrane separation device A sewage treatment method in which the concentrated water after the solid-liquid separation treatment is overflowed on a trough and returned to the anoxic tank.