JP2019126760A - Sewage treatment system and stirring device - Google Patents

Abstract

To reduce a site area of a sewage treatment system.SOLUTION: A sewage treatment system 1 that treats water to be treated by a biological treatment method includes a pre-treatment tank 2 and a post-treatment tank 3, the pre-treatment tank 2 further including: a first sedimentation basin 21; and an anaerobic compartment 51 and a first anoxic compartment 53 as a pre-stage of a biological treatment unit 5 that performs biological treatment to the water to be treated, the post-treatment tank 3 further including: a final settling basin 32; a second anoxic compartment 55 as a subsequent stage of the biological treatment unit 5; an aeration compartment 571; and a sedimentation compartment 572.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wastewater treatment system for treating wastewater with a biological treatment method and a stirring apparatus used therefor.

  Conventional standard sewage treatment first separates sludge in the sedimentation basin, and then generates Brock, nitrogen, phosphorus, etc. by biological treatment in the reaction tank to produce floc, and then the final sedimentation basin. The sludge is further separated at, and the treated water is discharged. That is, the system for performing this sewage treatment is composed of three tanks: a first settling tank, a reaction tank, and a final settling tank.

  The high-speed filtration method, the inclined plate method, and the like are provided as techniques for enhancing the functions of the first settling basin and the final settling basin (hereinafter, both are simply referred to as simply "settling basin"). In addition, in the case of the gravity settling method, the sedimentation basin requires a large site because of the restriction on the water area load required for separation of solids. Furthermore, since a scum is generated and floats up in the sedimentation basin, the removal mechanism (for example, a pipe type scum skimmer, a water sprinkler, etc.) is usually provided.

  In addition, as a function enhancement technique for the reaction tank, an advanced treatment method having an enhanced function is used with respect to a normal standard activated sludge method. Advanced treatment methods include anaerobic anaerobic anaerobic method (A2O method), carrier method, membrane separation activated sludge method (MBR method) and the like.

JP 9-47783 A

  However, the conventional sewage treatment by the advanced treatment method requires an anaerobic tank for removing phosphorus, an anaerobic tank for removing nitrogen, and / or an aerobic tank mainly for removing BOD for biological treatment. The tank and the anoxic tank require a stirrer, and the aerobic tank requires an aerator. For this reason, a plurality of aquarium enclosures and site areas are required.

  In addition, as described above, the ability of the gravity sedimentation type sedimentation basin depends on the water area load, so to secure a sufficient capacity, a large ground area and a water tank frame are required. If a high-speed filtration method or an inclined plate method is adopted to reduce the area of the sedimentation basin, maintenance and power costs are required.

  This invention is made | formed in view of said subject, and it aims at reducing the site area of a water treatment system.

  The wastewater treatment system according to one aspect of the present invention is a wastewater treatment system for treating water to be treated by a biological treatment method, which comprises: biological treatment for the first sedimentation tank and the water to be treated It has the composition provided with the pre-treatment tank provided with the front part of a final treatment part, the post-treatment tank provided with the latter part of the above-mentioned biological treatment part, and a final sedimentation tank.

  With this configuration, the first stage of the biological treatment unit is provided in the pretreatment tank together with the first sedimentation basin, and the second stage of the biological treatment unit is provided in the posttreatment tank together with the final sedimentation basin. Can be downsized and the required site area can be reduced.

  The front stage of the biological treatment unit may include an anaerobic zone and a first anoxic zone, and the rear stage of the biological treatment unit may include an aerobic zone.

  According to this configuration, it is possible to perform processing by the A2O method which is a high-level processing method as biological processing.

  The subsequent stage of the biological treatment unit may further include a second anoxic compartment.

  With this configuration, even when the residence time in the first anoxic section of the pretreatment tank is insufficient, sufficient post-treatment tank can perform sufficient anoxic treatment.

  The aerobic section may be composed of an aeration section that performs aeration and a sedimentation section that settles sludge.

  With this configuration, since the settling section is provided, the settling of sludge in the final settling tank can be assisted.

  The anaerobic compartment may have an opening at the bottom, and a first scraper that scrapes sludge into the first settling basin may be provided below the opening of the anaerobic compartment.

  With this configuration, sludge can be collected by being settled even in the anaerobic compartment, so that the initial settling basin can be designed smaller than the case where the sludge is settled only by the first settling basin.

  The first oxygen-free compartment may have an opening at the bottom thereof, and a first scraper that scrapes sludge into the first sedimentation basin is provided below the opening of the first oxygen-free compartment. It's okay.

  With this configuration, it is possible to settle and recover the sludge also in the first anoxic compartment, so it is possible to design the first settling tank smaller than when settling the sludge only in the first settling tank.

  The aerobic section may have an opening at the bottom, and a second scraper may be provided below the opening of the aerobic section to scrape sludge into the final sedimentation basin.

  With this configuration, sludge can be collected by being settled even in the aerobic compartment, so that the final sedimentation basin can be designed smaller than the case where the sludge is sedimented only by the final sedimentation basin.

  A first scraper that scrapes sludge that has settled from the front stage of the biological treatment section to the first sedimentation basin may be provided below the front stage of the biological treatment section.

  With this configuration, the sludge can be settled and recovered even in the previous stage of the biological treatment section, so that the initial settling basin can be designed smaller than the case where the sludge is settled using only the first settling basin.

  A second scraper that scrapes the sludge that settles from the latter stage of the biological treatment section to the final sedimentation basin may be provided below the latter stage of the biological treatment section.

  With this configuration, the sludge can be collected by being settled even in the subsequent stage of the biological treatment unit, so that the final sedimentation basin can be designed to be smaller than the case where the sludge is sedimented only by the final sedimentation basin.

  An overflow mechanism that removes scum and discharges water to be treated may be provided in the upper part of the final sedimentation basin.

  With this configuration, the treated water can be discharged by removing the scum.

  The sewage treatment system may further include a return mechanism that pulverizes the scum removed from the post-treatment tank and returns the scum together with the sludge settled in the final sedimentation tank to the pre-treatment tank.

  With this configuration, scum treatment such as inactivation of actinomycetes can be performed in the pretreatment tank.

  The casing of the pre-treatment tank and the casing of the post-treatment tank may have the same shape in which the first settling basin and the final settling basin correspond.

  By this structure, the housing of a pre-processing tank and the housing of a post-processing tank can be made into the same shape, and manufacturing cost can be held down.

  The pre-treatment vessel may have the first settling basin upstream and may have a pre-stage of the biological treatment section downstream, and below the pre-stage of the biological treatment section, The biological treatment section may have a first scraping section for scraping sludge deposited from the front stage of the biological processing section to the first settling tank, and the post-treatment tank may be upstream of the biological processing section. The final sedimentation basin may be provided on the downstream side, and sludge precipitated from the subsequent stage of the biological treatment unit is placed in the final sedimentation basin below the rear stage of the biological treatment unit. It may have a 2nd scraping part which scrapes, and the sewage discharged from the downstream of the pre-treatment tank may be supplied to the upstream of the post-treatment tank.

  By this structure, the sewage treatment system which shifts in order of an initial sedimentation tank, a biological treatment part, and a final sedimentation tank is comprised in two tanks, a pre-treatment tank and a post-treatment tank, as a whole.

  The stirring apparatus according to one aspect of the present invention is a stirring apparatus used at a stage before the biological treatment unit of the sewage treatment system or at a stage after the biological treatment unit of the sewage treatment system An apparatus, a longitudinal rotation shaft that is rotationally driven by the rotational drive device, and a stirring blade supported by the longitudinal rotation shaft, the stirring blade being in a direction perpendicular to the longitudinal rotation shaft or parallel to the longitudinal rotation shaft It has a configuration provided with a stirring action part forming an upward flow and a sedimentation action forming a downward flow parallel to the longitudinal rotation axis.

  According to this configuration, it is possible to realize the stirring function and the sludge settling function in the biological processing unit.

  The stirring blade may have an inclined surface that is inclined with respect to the longitudinal rotation axis.

  With this configuration, both sides can be effectively used on the inclined surface.

  According to the present invention, since the former stage of the biological treatment unit is provided in the pretreatment tank together with the first settling tank, and the latter stage of the biological treatment unit is provided in the aftertreatment tank together with the final settling tank, The aquarium housing can be downsized and the required site area can be reduced.

FIG. 1: is a figure which shows typically the whole structure of the sewage treatment system of embodiment of this invention. FIG. 2 is a diagram schematically showing the configuration of the pretreatment tank according to the embodiment of the present invention. FIG. 3: is a figure which shows typically the structure of the stirring apparatus of embodiment of this invention. FIG. 4A is a perspective view illustrating an example of a schematic shape of the stirring device according to the embodiment of the present invention, and FIG. 4B illustrates an example of a schematic shape of the stirring device according to the embodiment of the present invention. It is a top view which shows and FIG.4 (c) and FIG.4 (d) are figures which show an example of the inclination of the stirring blade of the stirring apparatus of embodiment of this invention. FIG. 5 is a diagram schematically showing the configuration of the post-treatment tank according to the embodiment of the present invention. FIG. 6 is an AA cross-sectional view of the post-treatment tank according to the embodiment of the present invention. FIG. 7 is a view schematically showing the overflow mechanism according to the embodiment of the present invention. FIG. 8 is a view schematically showing the overflow mechanism according to the embodiment of the present invention. FIG. 9 is a plan view schematically showing the overflow mechanism according to the embodiment of the present invention. FIG. 10 is a plan view schematically showing the overflow mechanism of the embodiment of the present invention. FIG. 11 is a view schematically showing the connection between the sludge return mechanism and the overflow mechanism according to the embodiment of this invention. FIG. 12 is a diagram schematically showing the details of the sludge return mechanism according to the embodiment of the present invention. FIG. 13 is a view schematically showing an example of a stirring blade group according to the embodiment of the present invention. FIG. 14 is a view schematically showing an example of a stirring blade group according to the embodiment of the present invention. Fig.15 (a) is a front view which shows typically an example of the stirring-blade group of embodiment of this invention, FIG.15 (b) is a top view of the example of Fig.15 (a). Fig.16 (a) is a top view which shows typically an example of the stirring blade group of embodiment of this invention, FIG.16 (b) is a top view of the example of Fig.16 (a). FIG. 17 is a plan view schematically showing an example of a stirring blade group according to the embodiment of the present invention. Fig. 18 (a) is a front view schematically showing an example of a stirring blade group according to the embodiment of the present invention, and Fig. 18 (b) is a plan view of the example of Fig. 18 (a). FIG. 19A is a plan view schematically showing an example of the stirring blade group according to the embodiment of the present invention, and FIG. 19B is a plan view of the example of FIG. 19A. FIG. 20 is a plan view schematically showing an example of a stirring blade group according to the embodiment of the present invention. Fig.21 (a) is a front view which shows typically an example of the stirring blade group of embodiment of this invention, FIG.21 (b) is a top view of the example of Fig.21 (a). Fig.22 (a) is a front view which shows typically an example of the stirring blade group of embodiment of this invention, FIG.22 (b) is a top view of the example of Fig.22 (a). FIG. 23 is a plan view schematically showing an example of a stirring blade group according to the embodiment of the present invention. Fig.24 (a) is a front view which shows typically an example of the stirring blade group of embodiment of this invention, FIG.24 (b) is a top view of the example of Fig.24 (a). FIG. 25 (a) is a front view schematically showing an example of the stirring blade group according to the embodiment of the present invention, and FIG. 25 (b) is a plan view of the example of FIG. 25 (a). FIG. 26 is a plan view schematically showing an example of a stirring blade group according to the embodiment of the present invention. FIG. 27 (a) is a front view schematically showing an example of a stirring blade group according to the embodiment of the present invention, and FIG. 27 (b) is a plan view of the example of FIG. 27 (a). Fig.28 (a) is a front view which shows typically an example of the stirring-blade group of embodiment of this invention, FIG.28 (b) is a top view of the example of Fig.28 (a). FIG. 29 is a plan view schematically showing an example of a stirring blade group according to the embodiment of the present invention. FIG. 30 is a view for explaining the action of the stirring blade having a plane perpendicular to the rotational direction. FIG. 31 is a view for explaining the action of the stirring blade having a surface inclined with respect to the rotation direction.

  Hereinafter, a sewage treatment system according to an embodiment of the present invention will be described with reference to the drawings. The embodiment described below shows an example in the case of practicing the present invention, and the present invention is not limited to the specific configuration described below. In carrying out the present invention, a specific configuration according to the embodiment may be adopted as appropriate.

  FIG. 1 is a diagram schematically showing an overall configuration of a sewage treatment system according to an embodiment of the present invention. As shown in FIG. 1, the sewage treatment system 1 includes a pretreatment tank 2, a posttreatment tank 3, and a sludge return mechanism 4. The sewage to be treated is introduced into the inflow side (upstream side) of the pretreatment tank 2, receives the treatment in the pretreatment tank 2, and discharges the pretreatment tank 2 from the discharge side (downstream side) of the posttreatment tank 3. It is introduced into the inflow side (upstream side), discharged from the discharge side (downstream side) of the post-treatment tank 3 and discharged. Hereinafter, the wastewater treated in the pretreatment tank 2 and the post-treatment tank 3 is also referred to as “treatment target water”. The sludge return mechanism 4 returns the sludge obtained in the post-treatment tank 3 to the pretreatment tank 2.

  The wastewater treatment system 1 according to the present embodiment performs the A2O method, which is advanced treatment, as biological treatment. A part of the configuration for performing the biological treatment is provided in the rear stage of the pretreatment tank 2, and the remaining part is provided in the front stage of the posttreatment tank. In other words, the latter part 22 of the pretreatment tank 2 is configured to perform part of the former stage of biological treatment, and the former stage 31 of the post-treatment tank 3 is configured to perform part of the latter stage of biological treatment The biological treatment unit 5 is configured by the rear stage of the pretreatment tank 2 and the front stage of the post-treatment tank 3. In other words, the first settling basin 21 is formed on the upstream side of the pretreatment tank 2, and the final settling basin 32 is formed on the downstream side of the posttreatment tank 3, and the biological treatment unit 5 is interposed therebetween. Provided.

  In the lower part of the front stage of the biological treatment unit 5 in the pretreatment tank 2, sludge, sand, residue, contaminants, etc. which have been deposited from the front stage of the biological treatment unit 5 are first collected in the sedimentation tank 21. A sediment collection unit 23 is provided, and a sediment collection unit that collects sludge that has settled from the subsequent stage of the biological treatment unit 5 in the final sedimentation basin 32 below the rear stage of the biological treatment unit 5 in the post-treatment tank 3. 33 is provided.

  The sludge return mechanism 4 includes a pipe 48 for returning sludge and a pump 42 and a scum pit 41 for mixing the sludge deposited in the final settling tank 32 and the scum floating in the final settling tank 32. The piping 48 is disposed to connect the final sedimentation basin 32 and the scum pit 41, and the scum pit 41 and the anaerobic section 51 and the first sedimentation basin 21.

  FIG. 2 is a diagram schematically showing the configuration of the pretreatment tank according to the embodiment of the present invention. In the pretreatment tank 2, the first settling tank 2 is formed on the upstream side, and the anaerobic section 51 and the first oxygen-free section 53 are formed on the downstream side of the first settling tank 2 as a stage to perform the advanced treatment. ing. Specifically, an anaerobic section 51 is formed on the downstream side of the first sedimentation basin 21, and a first anoxic section 53 is formed on the downstream side of the anaerobic section 51.

  The height of the pretreatment tank 2 is desirably 5 to 10 m, and is 7 m in the present embodiment. In the pretreatment tank 2, a portion corresponding to the first settling basin 21 is formed deeper than the other portions so that the sludge settled in the upstream first settling basin 21 does not flow downstream. The pretreatment tank 2 may be made of RC or steel plate.

  Since watertightness is not necessary for the division between the first sedimentation tank 2 and the anaerobic compartment 51 and the division between the anaerobic compartment 51 and the first oxygen-free compartment 53, structures using simple partition plates may be employed. In these partition plates, an opening 501 communicating the first settling basin 21 with the anaerobic section 51, and an opening 503 communicating the anaerobic section 51 with the first oxygen-free section 52 are formed. The openings 501 and 503 are formed so as to be located below the surface of the water to be treated in the pretreatment tank 2. A plurality of openings may be formed in the partition plate.

  Further, an opening 502 is formed on the bottom of the anaerobic section 51, and an opening 504 is formed on the bottom of the first oxygen-free section 53. In the example of FIG. 2, one opening is formed in the center of the bottom surface members of the anaerobic compartment 51 and the first anaerobic compartment 53, but the bottoms of the anaerobic compartment 51 and the first anaerobic compartment 53 are entirely covered. The openings 502 and 504 may be formed by being released, or a plurality of openings may be formed in the bottom member.

  A first scraping device 230 is provided in the lower portion of the precipitation recovery unit 23 at the front stage of the biological treatment unit 5 including the anaerobic section 51 and the first anoxic section 53. The first scraping machine 230 includes a drive device 231, an endless chain 232, a first driven wheel 233, and a second driven wheel 234. The drive device 231 includes a drive wheel (not shown) for rotating the endless chain 232. The endless chain 232 is bridged by the drive wheel of the drive device 231, the first driven wheel 233, and the second driven wheel 234, and is rotationally driven.

  Flight (not shown) is fixed to the endless chain 232 at a predetermined interval, and sludge that has settled from the front stage of the biological treatment unit 5 by this flight is scraped to the first sedimentation tank 21. As the first scraping machine 230, a twin-screw chain flight type or monorail type sludge scraping machine can be adopted so as not to interfere with the anaerobic section 51 and the first oxygen-free section 53 above it.

  The anaerobic section 51 is provided with a mechanical stirring device 52 for stirring and mixing the return sludge and the water to be treated flowing from the first settling tank 21. The stirring device 52 rotates at a low speed of about 10 rpm, for example.

  FIG. 3: is a figure which shows typically the structure of the stirring apparatus of embodiment of this invention. The stirring device 52 includes a vertical rotation shaft 522, a drive device 521 that rotationally drives the vertical rotation shaft 522, and a stirring blade group 523 supported by the vertical rotation shaft 522. The stirring blade group 523 has a stirring action portion 5231 that forms a flow in a direction perpendicular to the longitudinal rotation shaft 522 in the outer portion, and a settling action portion that forms a downward flow in parallel to the longitudinal rotation shaft 522 in the inner portion. 5232. The stirring blade group 523 has a swirling function in the outer part and has a settling function in the inner part.

  FIG. 4A is a perspective view illustrating an example of a schematic shape of the stirring device according to the embodiment of the present invention, and FIG. 4B illustrates an example of a schematic shape of the stirring device according to the embodiment of the present invention. It is a top view which shows and FIG.4 (c) and FIG.4 (d) are figures which show an example of the inclination of the stirring blade of the stirring apparatus of embodiment of this invention. In this example, as shown in FIG. 4 (a), the stirring blade group 523 is supported by the vertical rotation shaft 522, and as a whole has a rectangular parallelepiped shape with a side of 3 m, and the area of the projection plane is 9 square m. (3 m × 3 m). The stirring blade group 523 having this size is used for the anaerobic section 51 having a width of 6 m, for example. As shown in FIG. 4B, when the vertical rotation shaft 522 rotates, the stirring blade group 523 rotates in a circle having a diameter of about 4.3 m.

  Further, as shown in FIGS. 4C and 4D, the surface area of the inclined plate used for the stirring blade group 523 is 0.6 square m (0.2 m × 3 m), and the inclination angle is 60 degrees. The distance between the inclined plates is 0.1 m in the horizontal direction and 0.18 m in the longitudinal direction, the number of steps of the inclined plates is 16 (3 m × 0.18 m), and the number of rows of the inclined plates is 30 (3 m 0.1 m), the total number of inclined plates is 480 (16 stages × 30 rows), and the effective sedimentation area is 140 square m (≈surface area × total number × cos 60 °).

  Returning to FIG. 2, the first anoxic section 52 is provided with a mechanical stirring device 54 for stirring the water to be treated flowing from the anaerobic section 51. The stirring device 54 has the same configuration as the stirring device 52, and includes a vertical rotation shaft 542, a drive device 541 for rotating the vertical rotation shaft 542, and a stirring blade group 543 supported by the vertical rotation shaft 542. ing.

  FIG. 5 is a diagram schematically showing the configuration of the post-treatment tank according to the embodiment of the present invention. The post-treatment tank 3 is formed with a second anoxic compartment 55 and an aerobic compartment 57 as a configuration for performing the post-stage of the advanced treatment on the upstream side, and a final sedimentation basin 32 is formed downstream of the aerobic compartment 57. ing. Specifically, the aerobic section 57 is formed on the downstream side of the second anoxic section 55, and the final settling tank 32 is formed on the downstream side of the aerobic section 57. The aerobic section 57 includes an aeration section 571 formed on the downstream side of the second anoxic section 55 and a sedimentation section 572 formed on the downstream side thereof.

  The height of the post-treatment tank 3 is desirably 5 to 10 m, and is 7 m in the present embodiment. Moreover, in this Embodiment, the housing of the pretreatment tank 2 and the housing of the post-treatment tank 3 have the same shape with which the first sedimentation tank 21 and the final sedimentation tank 32 correspond. The post-treatment tank 3 may be made of RC or steel plate.

  The division between the second anoxic compartment 55 and the aeration compartment 571, the division between the aeration compartment 571 and the sedimentation compartment 572, and the division between the sedimentation compartment 572 and the final sedimentation tank 32 do not require watertightness, so simple partitioning is possible. A plate structure may be employed. The partition plate between the second anaerobic section 55 and the aeration section 571 crosses the surface of the processing target water, and the processing target water flows into the aeration section 572 from the lower part of the second anoxic section 55. Further, the upper end of the partition plate between the aeration section 571 and the sedimentation section 572 is located below the water surface of the water to be treated, and the water to be treated flows over the partition plate and flows from the aeration section 571 into the sedimentation section 572.

  An opening 505 is formed on the bottom of the second anoxic section 55, an opening 506 is formed on the bottom of the aeration section 571, and an opening 507 is formed on the bottom of the settling section 572. In the example of FIG. 5, the bottom members are not provided in the second anoxic section 55, the aeration section 571 and the sedimentation section 572 and the bottom is completely released to form the respective openings 504, 506 and 507. However, instead of this, a bottom surface member may be provided and one opening may be formed in the center thereof, or a plurality of openings may be formed in the bottom surface member.

  At the lower part of the aeration section 571, two diffuser plates 59 are provided so as to cover the opening 506. The diffuser plate 59 is connected to an aeration source (not shown) that supplies air, and has fine holes formed on the surface. The air supplied from the aeration source is released from the micropores of the aeration plate 59 and makes air-liquid contact with the water to be treated in the aeration section 571.

  FIG. 6 is an AA cross-sectional view of the post-treatment tank according to the embodiment of the present invention. In the aeration section 571, the entire area aeration is performed, that is, the ratio of the area of the aeration section 571 including the aeration plate 59, piping, and a part without a diffusion member including a rack is 20 to 40%, preferably 30%. The method is adopted. Thus, the amount of sludge that circulates back to the aeration section 571 and returns to the aeration section 571 after being settled from the periphery of the diffusion plate 59 in the aeration section 571 can be reduced.

  Returning to FIG. 5, a second scraper 330 is provided in the sediment collection unit 33 below the aerobic section 57. The second scraping device 330 includes a drive device 331, an endless chain 332, a first driven wheel 333 and a second driven wheel 334. The drive device 331 includes drive wheels (not shown) for rotating the endless chain 332. The endless chain 332 is bridged by the drive wheel of the drive device 331, the first driven wheel 333 and the second driven wheel 334 and is rotationally driven.

  A flight (not shown) is fixed to the endless chain 332 at a predetermined interval, and sludge that has settled from the aerobic section 57 by this flight is scraped to the final sedimentation basin 21. As the second scraping machine 330, a two-shaft chain flight type or monorail type sludge scraping machine can be adopted so as not to interfere with the aerobic section 57 located thereabove.

  The second oxygen-free section 55 includes a mechanical stirring device 56 for stirring the processing target water flowing from the pretreatment tank 2. The stirring device 56 has the same configuration as the stirring device 52, and includes a longitudinal rotation shaft 562, a drive device 561 that rotationally drives the longitudinal rotation shaft 562, and a stirring blade group 563 supported by the longitudinal rotation shaft 562. ing.

  The sedimentation section 572 includes a mechanical stirring device 58 for stirring the processing target water flowing from the aeration section 571. The stirring device 58 has the same configuration as the stirring device 52, and includes a vertical rotation shaft 582, a drive device 581 that rotationally drives the vertical rotation shaft 582, and a stirring blade group 583 supported by the vertical rotation shaft 582. ing. An overflow mechanism 34 is provided in the upper part on the downstream side of the post-treatment tank 3.

  FIG. 7 is a view schematically showing the overflow mechanism according to the embodiment of the present invention. The overflow mechanism 34 includes a cylindrical screen 341 and a driving device 342 that rotationally drives the cylindrical screen 341. The cylindrical screen 341 removes scum by the screen by passing the water to be treated from the outside to the inside. The clear water to be treated from which the scum has been removed flows in the cylindrical screen 341 in the axial direction. The mesh width of the cylindrical screen 341 is 0.1 to 3 mm, more preferably about 0.5 to 3 mm. The driving device 432 rotates the cylindrical screen 341 intermittently or always.

  FIG. 8 is a view schematically showing the overflow mechanism according to the embodiment of the present invention. The overflow mechanism 34 includes a cleaning spray 343 that jets water to the outside of the cylindrical screen 341 to remove scum trapped on the screen. Further, in the cylindrical screen 341, the shaft 3411 is supported by a bearing 344 provided in the post-processing tank 3. On the downstream side of the cylindrical screen 341, a scum discharge path 345 for discharging a scum that can not pass through the screen of the cylindrical screen 34 is formed. The cleaning spray 343 may be configured and arranged to spray water from the inside to the outside of the screen. In this case, the cleaning spray 343 is arranged so as to inject water in a direction toward the scum discharge path 345.

  FIG.9 and FIG.10 is a top view which shows typically the overflow mechanism of embodiment of this invention. The cylindrical screen 341 is installed in the post-processing tank 3 with a gap at both ends. A movable wedge 346 which can move up and down is provided between both ends of the cylindrical screen 341 and the post-processing tank 3. The scum discharge path 345 has a length similar to that of the cylindrical screen 341 and is installed in the post-treatment tank 3 with a gap at both ends. Further, a connecting path 348 that connects the scum discharge path 345 and the scum pit 41 provided outside the post-treatment tank 3 is provided.

  Normally, as shown in FIG. 9, the movable weir 346 is raised, and all the water to be treated passes through the cylindrical screen 341 from the outside to the inside, and flows in the axial direction on the inside, and the scum discharge passage 345 and the post-treatment tank 3 is discharged from the outlet 349. When the amount of water to be treated is large, such as when it is closed or rainy, the water to be treated overflows through the movable weir 346, or the movable weir 346 is lowered as shown in FIG. A part of the water to be treated is discharged through the cylindrical screen 341, and a part of the water to be treated is discharged through the movable weir 346 without passing through the cylindrical screen 341.

  FIG. 11 is a view schematically showing the connection between the sludge return mechanism and the overflow mechanism according to the embodiment of this invention. The sludge return mechanism 4 includes a scum pit 41, a pump 42, and a suction ejector 43. The suction ejector 43 is disposed in the scum pit 41. The speed of the sludge sucked from the bottom of the final settling tank 32 is increased by the pump 42 and injected into the suction ejector 43 so that the inside of the scum pit 41 is in a negative pressure state, and via the connecting rod 348 connected to the scum pit 41 The scum of the scum discharge path 345 is sucked into the flow path. By such suction, the scum is crushed.

  FIG. 12 is a diagram schematically showing the details of the sludge return mechanism according to the embodiment of the present invention. The sludge sucked up from the final sedimentation tank 32 by the pump 42 is supplied to the scum pit 41 through the scum suction main valve 45 through the pipe 44. The scum suction main valve 45 is driven to open and close by the drive device 46 in order to prevent excessive air suction due to air pulling. The scum pit 41 is provided with a water level gauge 47 which measures the water level in the scum pit 41.

  Operation | movement of the sewage treatment system 1 comprised as mentioned above is demonstrated. First, the sludge is introduced into the first sedimentation tank 21 on the upstream side of the pretreatment tank 2. In the first settling tank 21, sludge, sand, residue, impurities and the like in the water to be treated precipitate. The water to be treated that has first passed through the sedimentation tank 21 flows into the anaerobic section 51 formed in the pretreatment tank 2 through the opening 501.

  In the anaerobic section 51, a return sludge is added to the water to be treated and stirred in an anaerobic state to perform dephosphorization treatment on the water to be treated as activated sludge. Here, as the stirring device 52 of the anaerobic section 51 rotates, as described above, the stirring blade group 523 is rotated, a downward flow is generated by the sedimentation function inside, and an outward flow is generated by the swirl stirring function outside. Here, the sludge adhering to the inclined plate can be regarded as a simple fixed bed, and contributes to retention of the suspended matter concentration as the amount of sludge equivalent to the surface area.

  In the anaerobic section 51, due to the downward flow by the stirring device 52, the mud, sand, sediment, and impurities that were not able to be deposited in the settling tank 21 initially settle through the opening 502 to the precipitation recovery section 23. In this manner, in the anaerobic section 51, the gentle stirring and the sedimentation due to the action of the inclined surface are made compatible by operating the stirring device 52 provided with the stirring blade having the inclined surface at a low rotation speed. Return sludge is added to the anaerobic compartment 51. Thereby, the suspended solid concentration (MLSS) after the anaerobic section 51 is maintained. The anaerobic section 51 plays a role of securing the residence time necessary for the release of soluble phosphorus.

  The water to be treated which has undergone the dephosphorization treatment in the anaerobic zone 51 flows into the first anoxic zone 53 through the opening 503. In the first oxygen-free zone 53, the water to be treated is denitrified by stirring the water to be treated. The stirring device 54 provided in the first oxygen-free zone 53 also makes the downward flow inside and the outward flow outside, thereby stirring the water to be treated and sludge, sand, etc. from the water to be treated. Encourage sedimentation of sediment and impurities.

  In the first anoxic compartment 53, due to the downward flow by the stirring device 54, sludge, sand, residue, and contaminants that were not able to be deposited in the settling basin 21 and the anaerobic compartment 51 initially settle in the precipitation recovery section 23 through the opening 504. To do. As described above, by performing the low rotation operation of the stirring device 54 provided with the stirring blade having the inclined surface, both the gentle stirring and the sedimentation due to the action of the inclined surface are made compatible. The first oxygen-free section 53 plays a role of securing a residence time necessary for the denitrification process. The flows from the first settling tank 21 to the anaerobic section 51 and from the anaerobic section 51 to the first anoxic section 53 in the pretreatment tank 2 are natural flows.

  In the precipitation recovery unit 23, sludge, sand, sediment, and contaminants which have been deposited from the anaerobic section 51 and the first anoxic section 53 are scraped in the direction of the first settling tank 21 in flight, and then to the bottom of the first settling tank 21. Lead.

  The water to be treated is discharged from the downstream of the pretreatment tank 2, that is, the upper part of the downstream of the first oxygen-free zone 53, and introduced to the upstream of the post-treatment tank 3. In the second anoxic section 55 upstream of the post-treatment tank 3, a denitrification process is performed on the water to be treated following the first anoxic section 53. Further, similarly to the first oxygen-free zone 53, the stirring device 56 creates a downward flow while stirring the water to be treated. In addition, when the denitrification process can be sufficiently performed in the first oxygen-free section 53, the oxygen-free section may not be provided in the post-treatment tank 3. For example, when phosphorus removal is performed by chemical treatment such as PAC addition, the anaerobic section 51 of the pretreatment tank 2 becomes unnecessary, and the first anoxic section 53 of the pretreatment tank 2 can be enlarged. The anoxic compartment 55 can be omitted.

  The water to be treated that has flowed to the lower part of the second anoxic section 55 flows into the aeration section 571. In the aeration section 571, the air is discharged from the fine holes of the aeration plate 59 so that the air comes in contact with the water to be treated in the aeration section 571 and decomposes the organic matter, removes phosphorus, aerobically digests ammonia etc. Processing is performed. As described above, a diffuser plate 59 having a relatively large area is adopted, and a full-aeration air supply is performed.

  The sludge in the aeration section 571 settles in the precipitation recovery section 33 provided below the aerobic section 57 through the portion without the aeration member including the aeration plate 59 on the bottom surface. As described above, since the area of the aeration member is relatively large and the aperture ratio is small, it is possible to prevent the sludge that has settled in the sediment collection unit 33 from being stirred and returned to the aeration section 571.

  The aerobically treated water to be treated flows into the sedimentation section 572 near the water surface. In the sedimentation section 572, further aerobic treatment is performed using oxygen in the aeration section 571, and a downward flow is created by the agitator 58 to promote sludge sedimentation. In the precipitation recovery section 33, the sludge that has settled from the aerobic section 57 is scraped in the direction of the final sedimentation tank 32 in flight and led to the bottom of the final sedimentation tank.

  As described above, in the post-treatment tank 3, the second anoxia section 55 and the aeration section 571 communicate at the bottom from the upstream side, the aeration section 571 and the sedimentation section 572 communicate at the top, and the sedimentation section 572 and Since the bottom sediment communicates with the final sedimentation tank 32, the water to be treated receives the treatment in each section and flows from the upstream to the downstream.

  In the final sedimentation basin 32, sludge in the water to be treated has settled and scum is floating on the water surface. The scum is removed by the cylindrical screen 341 of the overflow mechanism 34 provided at the top of the final sedimentation tank 32, and the clear water to be treated is discharged from the outlet 349. The scum removed by the cylindrical screen 341 is accumulated in the scum discharge path 345 and supplied to the scum pit 41 through the connection path 348 as scum drainage.

  On the other hand, a part of the sludge that has settled at the bottom of the final sedimentation basin 32 is drawn out by the action of the pump 42 and conveyed toward the scum pit 41 through the pipe 48. In the scum pit 41, the scum is pulverized by joining the scum drainage and the sludge (returned sludge) extracted from the final sedimentation basin 32 by the suction ejector 43. The return sludge mixed with the scum is returned to the pretreatment tank 2 by the pipe 48. The scum is crushed by turbulent flow grinding even while flowing through the pipe 48 with the sludge. The returned sludge is first supplied to the settling basin 21 and the anaerobic compartment 51.

  By returning the returned sludge mixed with the aerated scum drainage to the upstream side of the first settling tank 21, the upstream side of the first settling tank 21 can be kept in a slightly aerobic state, and the generation of hydrogen sulfide can be suppressed. BOD adsorption can be accelerated.

  Below, the stirring blade 52 is demonstrated to an example for the various examples which the stirring apparatuses 52, 54, 56, 58 can employ | adopt. As described above, the stirring blade group 523 of the stirring device 52 has the stirring action portion 5231 that forms a flow in the direction perpendicular to the longitudinal rotation shaft 522 in the outer portion, and the lower portion parallel to the longitudinal rotation shaft 522 in the inner portion. It has a sedimentation action part 5232 that forms a directional flow. The stirring blade group 523 having both the stirring action part 5231 and the settling action part 5232 can be realized by the following various specific shapes.

  FIG. 13 is a view schematically showing an example of a stirring blade group according to the embodiment of the present invention. As shown in FIG. 13, the stirring blade group 523 may have a rectangular parallelepiped shape as a whole. In this case, an inclined plate inclined with respect to the longitudinal rotation shaft 522 may be used as the stirring action portion 5231 outside the stirring blade group 523.

  FIG. 14 is a view schematically showing an example of a stirring blade group according to the embodiment of the present invention. As shown in FIG. 14, the stirring blade group 523 may have a cylindrical shape as a whole. In this case, an inclined plate inclined with respect to the longitudinal rotation shaft 522 may be used outside the stirring blade group 523 as the stirring action portion 5231.

  Fig.15 (a) is a front view which shows typically an example of the stirring-blade group of embodiment of this invention, FIG.15 (b) is a top view of the example of Fig.15 (a). In addition, in FIG.15 (b), only a part of stirring blade is shown in figure and although another stirring blade is not shown in figure, it is rotationally symmetrical centering on the illustrated stirring blade and vertical rotation shaft 522. Installed. The same applies to the following examples. Moreover, in this example, the stirring blade group 523 has a rectangular parallelepiped shape as a whole.

  As shown in FIG. 15A, the stirring blade group 523 is divided in the vertical direction, and the positions of the stirring blades are aligned in the upper and lower stages. The stirring blade group 523 is divided into upper and lower two stages, but the stirring blade group 523 and the stirring blade group described below may be divided into a plurality of three or more stages. Further, as shown in FIG. 15B, the stirring device 523 has a frame 524 fixed to the vertical rotation shaft 522, and each stirring blade is fixed to this frame. The frame 524 includes a rectangular outer frame frame 5241 and a diagonal frame 5242 which is a diagonal line of the outer frame. Each stirring blade of the stirring blade group 523 is supported so as to be perpendicular to the side from the diagonal frame to the side of the nearest outer frame 5241.

  Fig.16 (a) is a top view which shows typically an example of the stirring blade group of embodiment of this invention, FIG.16 (b) is a top view of the example of Fig.16 (a). In this example, the stirring blade group 523 has a rectangular parallelepiped shape as a whole.

  As shown in FIG. 16A, the stirring blade group 523 is divided in the vertical direction, and the positions of the stirring blades at the upper and lower portions are shifted from each other. Further, as shown in FIG. 16 (b), the stirring device 52 has a frame 524 fixed to the vertical rotation shaft 522, and each stirring blade is fixed to the frame 524. The frame 524 is fixed to a rectangular outer frame frame 5241 and a diagonal frame 5242 which is a diagonal line of the outer frame. Each stirring blade of the stirring blade group 523 is supported so as to be perpendicular to the side from the diagonal frame 5242 to the side of the nearest outer frame 5241.

  FIG. 17 is a plan view schematically showing an example of a stirring blade group according to the embodiment of the present invention. In this example, the stirring blade group 523 has a rectangular parallelepiped shape as a whole. The agitator 52 has a frame 524 that is fixed to the longitudinal rotation shaft 522. The frame 524 is composed of a rectangular outer frame 5241 and a diagonal frame 5242 which is a diagonal of the outer frame. Also, in this example, each stirring blade is divided in and out, the inner stirring blade is fixed to the diagonal frame 5242, and the outer stirring blade is fixed to the outer frame 5241.

  FIG. 18A is a front view schematically showing an example of the stirring blade group according to the embodiment of the present invention, and FIG. 18B is a plan view of the example of FIG. In this example, the stirring blade group 523 has a rectangular parallelepiped shape as a whole.

  As shown in FIG. 18A, the stirring blade group 523 is divided in the vertical direction, each stirring blade is inclined with respect to the vertical rotation shaft 522, and the positions are aligned in the upper and lower stages. Further, as shown in FIG. 16 (b), the stirring device 52 has a frame fixed to the vertical rotation shaft 522, and each stirring blade is fixed to the frame 524. The frame 524 includes a rectangular outer frame frame 5241 and a middle frame 5243 that bisects the rectangle vertically and horizontally. Each stirring blade of the stirring blade group 523 is supported by the other middle frame 5243 so as to be parallel to one middle frame 5243.

  FIG. 19A is a plan view schematically showing an example of the stirring blade group according to the embodiment of the present invention, and FIG. 19B is a plan view of the example of FIG. 19A. In this example, the stirring blade group 523 has a rectangular parallelepiped shape as a whole.

  As shown in FIG. 19A, the stirring blade group 523 is divided in the vertical direction, and each stirring blade is inclined with respect to the vertical rotation shaft 522, and the positions thereof are shifted from each other in the upper and lower stages. . Further, as shown in FIG. 19 (b), the stirring device 52 has a frame 524 fixed to the vertical rotation shaft 522, and each stirring blade is fixed to the frame 524. The frame 524 is composed of a rectangular outer frame 5241 and a middle frame 5243 which divides the square into upper and lower and right and left respectively. Each stirring blade of the stirring blade group 523 is supported by the other middle frame 5243 so as to be parallel to one middle frame 5243.

  FIG. 20 is a plan view schematically showing an example of a stirring blade group according to the embodiment of the present invention. In this example, the stirring blade group 523 has a rectangular parallelepiped shape as a whole. The agitator 52 has a frame 524 that is fixed to the longitudinal rotation shaft 522. The frame 524 includes a rectangular outer frame frame 5241 and a middle frame 5243 that bisects the rectangle vertically and horizontally.

  In this example, each stirring blade of the stirring blade group 523 is divided inside and outside, and the inner stirring blade is fixed to the other middle frame 5243 so as to be parallel to one middle frame 5243, and the outer stirring blades Is fixed to the side of the outer frame 5241 parallel to the other middle frame 5243.

  Fig.21 (a) is a front view which shows typically an example of the stirring blade group of embodiment of this invention, FIG.21 (b) is a top view of the example of Fig.21 (a). In this example, the stirring blade group 523 has a rectangular parallelepiped shape as a whole.

  As shown in FIG. 21A, the stirring blade group 523 is divided in the vertical direction, and the respective stirring blades are aligned in the upper and lower stages. Further, as shown in FIG. 21 (b), the stirring device 52 has a frame 524 fixed to the vertical rotation shaft 522, and each stirring blade is fixed to the frame 524. The frame 524 includes a rectangular outer frame frame 5241 and a diagonal frame 5242 which is a diagonal line of the outer frame. Each stirring blade of the stirring blade group 523 is supported by the other diagonal frame 5242 so as to be parallel to one diagonal frame 5242.

  Fig.22 (a) is a front view which shows typically an example of the stirring blade group of embodiment of this invention, FIG.22 (b) is a top view of the example of Fig.22 (a). In this example, the stirring blade group 523 has a rectangular parallelepiped shape as a whole.

  As shown in FIG. 22 (a), the stirring blade group 523 is divided in the vertical direction, and the positions of the stirring blades at the upper and lower portions are shifted from each other. Further, as shown in FIG. 22 (b), the stirring device 52 has a frame 524 fixed to the vertical rotation shaft 522, and each stirring blade is fixed to the frame 524. The frame 524 includes a rectangular outer frame frame 5241 and a diagonal frame 5242 which is a diagonal line of the outer frame. Each stirring blade of the stirring blade group 523 is supported by the other diagonal frame 5242 so as to be parallel to one diagonal frame 5242.

  FIG. 23 is a plan view schematically showing an example of a stirring blade group according to the embodiment of the present invention. In this example, the stirring blade group 523 has a rectangular parallelepiped shape as a whole. The agitator 52 has a frame 524 that is fixed to the longitudinal rotation shaft 522. The frame 524 includes a rectangular outer frame frame 5241 and a diagonal frame 5242 which is a diagonal line of the outer frame.

  In this example, each stirring blade of the stirring blade group 523 is divided inside and outside, and the inner stirring blade is supported by the other diagonal frame 5242 so as to be parallel to one diagonal frame 5242, These stirring blades are supported by the outer frame frame 5241.

  Fig.24 (a) is a front view which shows typically an example of the stirring blade group of embodiment of this invention, FIG.24 (b) is a top view of the example of Fig.24 (a). In this example, the stirring blade group 523 has a cylindrical shape as a whole.

  As shown in FIG. 24 (a), the stirring blade group 523 is divided in the vertical direction, and the positions of the stirring blades are aligned in the upper and lower stages. Moreover, as shown in FIG. 24 (b), the stirring device 52 has a frame 524 fixed to the vertical rotation shaft 522. The frame 524 is composed of a circular inner frame 5244 centered on the vertical axis of rotation 522 and a circular outer frame 5245 centered on the vertical axis of rotation 522 (concentric with the inner frame). The respective stirring blades of the stirring blade group 523 are arranged radially in a radial direction of a circle around the longitudinal rotation shaft 522 and are supported by the inner frame 5244 and the outer frame 5245.

  FIG. 25 (a) is a front view schematically showing an example of the stirring blade group according to the embodiment of the present invention, and FIG. 25 (b) is a plan view of the example of FIG. 25 (a). In this example, the stirring blade group 523 has a cylindrical shape as a whole.

  As shown in FIG. 25 (a), the stirring blade group 523 is divided in the vertical direction, and the positions of the stirring blades at the upper and lower portions are shifted from each other. Further, as shown in FIG. 25 (b), the stirring blade 52 has a frame fixed to the vertical rotation shaft 522. The frame 524 includes a circular inner frame 5244 centered on the vertical rotation shaft 522 and a circular outer frame 5245 centered on the vertical rotation shaft 522 (concentric with the inner frame 5244). The respective stirring blades of the stirring blade group 523 are arranged radially in a radial direction of a circle around the longitudinal rotation shaft 522 and are supported by the inner frame 5244 and the outer frame 5245.

  FIG. 26 is a plan view schematically showing an example of a stirring blade group according to the embodiment of the present invention. In this example, the stirring blade group 523 has a cylindrical shape as a whole. The stirring device 52 has a frame fixed to the vertical rotation shaft 522. The frame 524 includes a circular inner frame 5244 centered on the vertical rotation shaft 522 and a circular outer frame 5245 centered on the vertical rotation shaft 522 (concentric with the inner frame 5244).

  In this example, each stirring blade of the stirring blade group 523 is divided inside and outside. The inner stirring blades are radially arranged in a radial direction of a circle centered on the vertical rotation shaft 522 and supported by the inner frame 5244. The outer stirring blades are radially arranged in the radial direction of a circle centered on the vertical rotation shaft 522 and supported by the outer frame 5245. The circumferential positions of the inner stirring blade and the outer stirring blade are aligned.

  FIG. 27 (a) is a front view schematically showing an example of a stirring blade group according to the embodiment of the present invention, and FIG. 27 (b) is a plan view of the example of FIG. 27 (a). In this example, the stirring blade group 523 has a cylindrical shape as a whole.

  As shown in FIG. 27A, the stirring blade group 523 is divided in the vertical direction, and the positions of the stirring blades are aligned in the upper and lower stages. Further, as shown in FIG. 27A, the stirring device 52 has a frame fixed to the vertical rotation shaft 522. The frame 524 is composed of a circular inner frame 5244 centered on the vertical rotation axis 522 and an outer frame 5245 centered on the vertical rotation axis 522 (concentric with the inner frame 5244). Each stirring blade of the stirring blade group 523 is bent and extended around the vertical rotation shaft 522 and supported by the inner frame 5244 and the outer frame 5245. The shape and the bending direction of each stirring blade are the same.

  Fig.28 (a) is a front view which shows typically an example of the stirring-blade group of embodiment of this invention, FIG.28 (b) is a top view of the example of Fig.28 (a). In this example, the stirring blade group 523 has a cylindrical shape as a whole.

  As shown in FIG. 28A, the stirring blade group 523 is divided in the vertical direction, and the positions of the stirring blades are shifted from each other in the upper and lower stages. Further, as shown in FIG. 28A, the stirring device 52 has a frame fixed to the longitudinal rotation shaft 522. The frame 524 is composed of a circular inner frame 5244 centered on the vertical rotation axis 522 and an outer frame 5245 centered on the vertical rotation axis 522 (concentric with the inner frame 5244). Each stirring blade of the stirring blade group 523 is bent and extended around the vertical rotation shaft 522 and supported by the inner frame 5244 and the outer frame 5245. The shape and the bending direction of each stirring blade are the same.

  FIG. 29 is a plan view schematically showing an example of a stirring blade group according to the embodiment of the present invention. In this example, the stirring blade group 523 has a cylindrical shape as a whole. The stirring device 52 has a frame fixed to the vertical rotation shaft 522. The frame 524 includes a circular inner frame 5244 centered on the vertical rotation shaft 522 and a circular outer frame 5245 centered on the vertical rotation shaft 522 (concentric with the inner rotation).

  In this example, each stirring blade of the stirring blade group 523 is divided inside and outside. The inner stirring blade is supported by the inner frame 5244 and extends while curving outward. The outer stirring blade is supported by the outer frame 5245 and extends from the outer frame 5245 while curving inward. The circumferential positions of the inner stirring blade and the outer stirring blade are aligned.

  FIG. 30 is a view for explaining the action of the stirring blade having a plane perpendicular to the rotation direction, and FIG. 31 is a view for explaining the action of the stirring blade having a plane inclined to the rotation direction. First, the larger the number of stirring blades, the larger the planar area and the higher the stirring effect, but the smaller the size, the smaller the weight and the steel material cost. Also, the greater the number of rotations, the greater the moving effect, and the smaller the number of rotations, the longer the contact time.

  As shown in FIG. 30, when the stirring blade is perpendicular to the rotation direction, the sludge contacts only on one side of the stirring blade, but the stirring blade is inclined with respect to the rotation direction as shown in FIG. In this case, both surfaces of the stirring blade can be used effectively.

  As described above, according to the sewage treatment system 1 of the embodiment of the present invention, the function of the conventional sewage treatment system including at least three tanks of the first sedimentation tank, the advanced treatment tank, and the final sedimentation tank is the pretreatment tank 2. And the post-treatment tank 3, the site area can be reduced as compared with the conventional wastewater treatment system.

  Further, in the pretreatment tank 2, in the anaerobic section 51 and the first oxygen-free section 52 that perform the advanced treatment, the settling mud, sand, residue, and foreign matter are collected by the lower sediment collection unit 23 and first precipitated. It can be transferred to the pond 21, and it becomes unnecessary to secure the flow velocity of the bottom flow velocity of 0.1 m / s or more of the anaerobic section 51 and the first oxygen-free section 52. Similarly, in the post-treatment tank 3, sludge settling in the aerobic section 57 where advanced treatment is performed can be recovered by the lower sediment recovery unit 33 and transferred to the final sedimentation tank 32.

  Moreover, in each division which performs an advanced process, the amount of sludge adhering to a stirring blade can be used as a pseudo fixed bed which changes to a biological treatment support | carrier by using the stirring apparatus provided with the stirring blade which has an inclined surface.

  Also, the stirrer used for each section that performs advanced processing has both a swirl stirring function and a sedimentation function because the inner stirring blades generate a downward flow and the outer stirring blades generate an outward flow. Can do.

  Further, since the overflow mechanism 34 is provided on the downstream side of the post-treatment tank 3, the scum can be discharged continuously, and the finishing process can be performed at the same time.

  Further, in the aeration section 571, a partition is provided in a plane by the diffuser plate 59 and a pipe for conveying air there, and the upper aeration section 571 and the lower precipitation collection section 33 are partitioned, so that the precipitation collection section The backflow of sludge from 33 to the aeration section 571 can be suppressed.

  In addition, since the sedimentation compartment 572 is provided in the aerobic compartment 57, it is possible to perform further aerobic treatment on the water to be treated that has become aerobic due to aeration in the aeration compartment 571 and to assist sedimentation of sludge.

  In addition, a movable weir 346 is provided on the downstream side of the post-treatment tank 3, and during normal operation, the movable weir 346 is set at an appropriate position to discharge only the treatment target water that has passed through the cylindrical screen 341. When the inflow load temporarily increases and exceeds the screen processing capacity of the cylindrical screen 341, the movable weir 346 is overflowed or the movable weir 346 is lowered to discharge the water to be treated that does not pass through the cylindrical screen 341. Therefore, the sewage treatment can be appropriately performed according to the inflow load.

  In the above embodiment, the treatment by the biological treatment unit 5 is performed by the advanced treatment A2O method, but the biological treatment performed by the biological treatment unit 5 is a carrier method, a membrane, or the like. Other advanced treatments such as separation activated sludge method (MBR method) may be used, or standard activated sludge method may be used. In these cases as well, the tank for carrying out it is configured integrally with the first settling basin 21 or the final settling basin 32, so that the entire sewage treatment system 1 includes the pretreatment tank 2 including the first settling basin 21. It can be comprised by two tanks with the post-processing tank 3 containing the final sedimentation tank 32, and can reduce a site area.

  Moreover, in said embodiment, the back | latter stage (anaerobic division 51 and the 1st anaerobic division 53) of the pretreatment tank 2 and the front | former stage (2nd anoxic division 55, the aeration division 571, and the sedimentation division 572) of the posttreatment tank 3 are mentioned. ) Are collectively referred to as the biological processing unit 5, but it is not necessary that all the processing be biologically performed in the biological processing unit 5, as is apparent from the above description. For example, the dephosphorization process may be a scientific process, and the sedimentation of sludge, sand, residue, impurities, etc. by the stirring blades in the above embodiment is a physical process.

  In the present invention, the first stage of the biological treatment unit is provided in the pretreatment tank together with the first sedimentation basin, and the second stage of the biological treatment unit is provided in the posttreatment tank together with the final sedimentation basin. It has the effect of being able to miniaturize the required site area, and is useful as a sewage treatment system or the like for treating sewage with a biological treatment method.

DESCRIPTION OF SYMBOLS 1 Sewage treatment system 2 pre-treatment tank 21 first sedimentation tank 22 post-stage of pre-treatment tank 23 precipitation collection part 230 1st scraping machine 3 post-treatment tank 31 front stage of post-treatment tank 32 final sedimentation tank 33 precipitation collection part 330 second scratch Auxiliary machine 34 Overflow mechanism 341 Cylindrical screen 342 Drive device 343 Cleaning spray 344 Bearing 345 Scum discharge path 346 Movable weir 348 Connection path 349 Outlet 4 Sludge return mechanism 41 Scum pit 42 Pump 43 Suction ejector 438 Connection path 44 Suction pipe 45 Scum Valve 46 Drive device 47 Water level gauge 48 Piping 5 Biological treatment unit 51 Anaerobic section 52, 54, 56, 58 Stirring device 521 Drive device 522 Vertical rotating shaft 523 Stirring blade group 524 Frame 53 1st oxygen free section 55 2nd no Oxygen compartment 57 Aerobic compartment 571 Aeration compartment 572 Sedimentation compartment

Claims (15)

A sewage treatment system for treating water to be treated by a biological treatment method,
A pretreatment tank comprising an initial sedimentation tank and a stage upstream of a biological treatment unit for performing biological treatment on the water to be treated;
A post-treatment tank comprising a stage downstream of the biological treatment section and a final settling tank,
Sewage treatment system with. The front stage of the biological treatment unit includes an anaerobic compartment and a first anoxic compartment,
The wastewater treatment system according to claim 1, wherein the downstream stage of the biological treatment unit includes an aerobic section.   The wastewater treatment system according to claim 2, wherein the downstream stage of the biological treatment unit further includes a second oxygen-free zone.   The sewage treatment system according to claim 2 or 3, wherein the aerobic section comprises an aeration section for performing aeration and a sedimentation section for settling sludge. The anaerobic compartment has an opening at the bottom,
The sewage treatment system according to any one of claims 2 to 4, wherein a first scraper for scraping sludge into the first settling basin is provided below the opening of the anaerobic section. The first anoxic compartment has an opening at the bottom;
The waste water treatment system according to any one of claims 2 to 4, wherein a first plow is provided below the opening of the first anoxic compartment to collect sludge in the first settling basin. The aerobic compartment has an opening at the bottom;
The sewage treatment system according to any one of claims 2 to 4, wherein a second scraper for scraping sludge into the final sedimentation tank is provided below the opening of the aerobic section.   The lower part of the front part of the biological treatment part is provided with a first scraper that scrapes the sludge that settles from the front part of the biological treatment part to the first sedimentation basin. The sewage treatment system according to any one of the above.   The second scraper for scraping the sludge that settles from the subsequent stage of the biological treatment unit to the final sedimentation basin is provided below the subsequent stage of the biological treatment unit. The sewage treatment system according to any one of the above.   The sewage treatment system according to any one of claims 1 to 9, wherein an overflow mechanism for removing scum and discharging the water to be treated is provided at the upper part of the final sedimentation tank.   The sewage treatment system according to claim 10, further comprising a return mechanism for pulverizing the scum removed from the post-treatment tank and returning the scum to the pre-treatment tank together with the sludge settled in the final sedimentation tank.   The sewage treatment system according to any one of claims 1 to 11, wherein the pretreatment tank casing and the posttreatment tank casing have the same shape corresponding to the first sedimentation basin and the final sedimentation basin. The pretreatment tank has the first sedimentation tank on the upstream side, has a front stage of the biological treatment unit on the downstream side, and has the biological treatment unit on the lower side of the front stage of the biological treatment unit. A first scraping unit for scraping sludge deposited from the former stage of
The post-treatment tank has the downstream side of the biological processing unit on the upstream side, the final sedimentation tank on the downstream side, and the biological processing unit below the downstream side of the biological processing unit. A second scraping portion for scraping the sludge precipitated from the latter stage to the final sedimentation basin,
The wastewater treatment system according to claim 1, wherein the wastewater discharged from the downstream of the pretreatment tank is supplied upstream of the post-treatment tank. A stirrer used in the front stage of the biological treatment section of the sewage treatment system according to claim 8 or the rear stage of the biological treatment section of the sewage treatment system according to claim 9,
A rotary drive,
A longitudinal rotation shaft that is rotationally driven by the rotational drive device;
A stirring blade supported by the longitudinal rotation shaft;
With
The stirring blade includes a stirring action part that forms a flow in a direction perpendicular to the longitudinal rotation axis and a settling action part that forms a downward flow parallel to the longitudinal rotation axis.   The stirring device according to claim 14, wherein the stirring blade has an inclined surface which is inclined with respect to the vertical rotation axis.

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