Wastewater treatment device and wastewater treatment method

Abstract

To provide a wastewater treatment device and a wastewater treatment method capable of decreasing an amount of chemicals to be used in treating a carrier holding bacteria for treating wastewater.SOLUTION: The wastewater treatment device comprises: a wastewater treatment tank 5 for treating wastewater using bacteria carried by a carrier 1; solid-liquid separation devices 6, 10 for separating the carrier 1 from the wastewater and a chemical; a first transfer device 7 for extracting a part of the carrier 1 and a part of the wastewater from the wastewater treatment tank 5 to transfer the same to the solid-liquid separation device 6; a carrier treatment tank 8 for treating the carrier 1 separated from the wastewater by the solid-liquid separation device 6 with the chemical; and a second transfer device 12 for extracting a part of the carrier and a part of the chemical from the carrier treatment tank 8 to transfer the same to the solid-liquid separation device 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a technology for carrying bacteria on the surface of a carrier (plastic / gel-based) to perform wastewater treatment, and in particular to a technology for treating the carrier with a chemical in order to maintain the treatment performance of the bacteria carried on the surface of the carrier or to carry only specific bacteria on the surface of the carrier. [Background technology]

[0002] Techniques for treating wastewater using carriers carrying specific bacteria have been proposed and implemented in the past, as disclosed in Patent Document 1. Patent Document 1 discloses a wastewater treatment device that includes a first tank into which wastewater is poured from the outside, a second tank into which wastewater from the first tank is poured, nitrification carriers containing unacclimated ammonia-oxidizing bacteria placed in the first tank, autotrophic denitrification carriers containing unacclimated anaerobic ammonium-oxidizing bacteria placed in the second tank, and a carrier transfer means for transferring the nitrification carriers from the second tank to the first tank.

[0003] In the first tank, the unacclimated ammonia-oxidizing bacteria are acclimated while nitrifying the ammoniacal nitrogen in the wastewater to nitrite nitrogen, and in the second tank, the unacclimated anaerobic ammonium-oxidizing bacteria are acclimated while simultaneously denitrifying the ammoniacal nitrogen in the wastewater poured from the first tank and the nitrite nitrogen in the wastewater. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-35215 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-189249 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to maintain the treatment performance of the bacteria carried on the carrier surface, or to carry only specific bacteria on the carrier surface, it is necessary to treat the carrier with a chemical. Specifically, the carrier is extracted from a wastewater treatment tank together with wastewater, transferred to a carrier treatment tank, and chemically treated in the carrier treatment tank. The chemically treated carrier is extracted from the carrier treatment tank together with the chemical, and transferred to a wastewater treatment tank.

[0006] However, in the carrier treatment tank, the chemicals are consumed not only by the carriers but also by the wastewater entrained with the carriers, resulting in a large amount of chemicals being used. Furthermore, the volume of the carrier treatment tank must be large enough to accommodate both the carriers and the wastewater. When the chemical-treated carriers are withdrawn from the carrier treatment tank, the chemicals are also withdrawn from the carrier treatment tank, so the chemicals must be replenished, resulting in a large amount of chemicals being used. Furthermore, if the carriers and the chemicals are returned to the wastewater treatment tank together, this may affect the treatment performance of the wastewater in the wastewater treatment tank.

[0007] Therefore, the present invention provides a wastewater treatment device and a wastewater treatment method that can reduce the amount of chemicals used to treat carriers that hold bacteria for treating wastewater. [Means for solving the problem]

[0008] In one aspect, a wastewater treatment device is provided, comprising: a wastewater treatment tank that treats wastewater using bacteria supported on a carrier; a solid-liquid separation device that separates the carrier from the wastewater and chemicals; a first transfer device that extracts a portion of the carrier and a portion of the wastewater from the wastewater treatment tank and transfers them to the solid-liquid separation device; a carrier treatment tank that treats the carrier separated from the wastewater by the solid-liquid separation device with the chemicals; and a second transfer device that extracts a portion of the carrier and a portion of the chemicals from the carrier treatment tank and transfers them to the solid-liquid separation device.

[0009] In one embodiment, the solid-liquid separation devices include a first solid-liquid separation device that separates the carrier from the wastewater, and a second solid-liquid separation device that separates the carrier from the chemicals, the first solid-liquid separation device is located above the carrier treatment tank so that the carrier separated by the first solid-liquid separation device falls from the first solid-liquid separation device into the carrier treatment tank, and the wastewater treatment device further includes a wastewater return passage that returns the wastewater separated by the first solid-liquid separation device to the wastewater treatment tank. In one embodiment, the solid-liquid separation device comprises a first solid-liquid separation device that separates the carrier from the wastewater, and a second solid-liquid separation device that separates the carrier from the chemicals, the second solid-liquid separation device being located above the wastewater treatment tank so that the carriers separated by the second solid-liquid separation device fall from the second solid-liquid separation device into the wastewater treatment tank, and the wastewater treatment device further comprises a chemical return passage that returns the chemicals separated by the second solid-liquid separation device to the carrier treatment tank.

[0010] In one embodiment, the solid-liquid separator includes a first solid-liquid separator that separates the carrier from the wastewater, and a second solid-liquid separator that separates the carrier from the chemical. In one embodiment, the first solid-liquid separation device is located above the carrier treatment tank so that the carrier separated by the first solid-liquid separation device falls from the first solid-liquid separation device into the carrier treatment tank, and the wastewater treatment device further includes a wastewater return passage for returning the wastewater separated by the first solid-liquid separation device to the wastewater treatment tank. In one embodiment, the second solid-liquid separation device is located above the wastewater treatment tank so that the carrier separated by the second solid-liquid separation device falls from the second solid-liquid separation device into the wastewater treatment tank, and the wastewater treatment device further includes a chemical return passage for returning the chemical separated by the second solid-liquid separation device to the carrier treatment tank. In one embodiment, the first solid-liquid separation device is located above the wastewater treatment tank so that the wastewater separated by the first solid-liquid separation device falls from the first solid-liquid separation device into the wastewater treatment tank, and the wastewater treatment device further includes a first carrier transfer passage that transfers the carrier separated by the first solid-liquid separation device to the carrier treatment tank. In one embodiment, the second solid-liquid separation device is located above the carrier treatment tank so that the chemicals separated by the second solid-liquid separation device fall from the second solid-liquid separation device into the carrier treatment tank, and the wastewater treatment device further includes a second carrier transfer passage that transfers the carriers separated by the second solid-liquid separation device to the wastewater treatment tank.

[0011] In one embodiment, the solid-liquid separation device includes a solid-liquid separation screen and a carrier distribution device that selectively distributes the carrier separated from the wastewater or the chemical by the solid-liquid separation screen to either the carrier treatment tank or the wastewater treatment tank. In one embodiment, the apparatus further includes a liquid sorting device that returns the wastewater that has passed through the solid-liquid separation screen to the wastewater treatment tank and returns the chemical that has passed through the solid-liquid separation screen to the carrier treatment tank. In one embodiment, the first transfer device and the second transfer device each include an air lift pump. In one embodiment, the first transfer device and the second transfer device each comprise a single screw pump. In one embodiment, the carrier is a gel-based carrier. In one embodiment, the carrier is a plastic carrier.

[0012] In one aspect, a wastewater treatment method is provided, which includes treating wastewater in a wastewater treatment tank with bacteria supported on a carrier, extracting a portion of the carrier and a portion of the wastewater from the wastewater treatment tank and transferring them to a solid-liquid separation device, separating the wastewater and the carrier using the solid-liquid separation device, returning the separated wastewater to the wastewater treatment tank, and transferring the separated carrier to a carrier treatment tank, treating the carrier with a chemical in the carrier treatment tank, extracting a portion of the carrier and a portion of the chemical from the carrier treatment tank and transferring them to the solid-liquid separation device, separating the chemical from the carrier using the solid-liquid separation device, returning the separated chemical to the carrier treatment tank, and transferring the separated carrier to the wastewater treatment tank. In one embodiment, the carrier is a gel-based carrier. In one embodiment, the carrier is a plastic carrier. [Effects of the Invention]

[0013] The solid-liquid separator can separate the wastewater extracted from the wastewater treatment tank from the carrier. Therefore, only the carrier can be transferred to the carrier treatment tank, and the wastewater can be returned to the wastewater treatment tank. Similarly, the solid-liquid separator can separate the chemical extracted from the carrier from the carrier. Therefore, only the carrier can be transferred to the wastewater treatment tank, and the chemical can be returned to the carrier treatment tank. As a result, the amount of chemical used can be reduced. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram illustrating an embodiment of a wastewater treatment device. [Figure 2] FIG. 10 is a schematic diagram showing another embodiment of the wastewater treatment device. [Figure 3] FIG. 10 is a schematic diagram showing still another embodiment of the wastewater treatment device. [Figure 4] FIG. 10 is a schematic diagram showing still another embodiment of the wastewater treatment device. [Figure 5] FIG. 5 is a diagram illustrating the operation of the wastewater treatment device shown in FIG. [Figure 6] FIG. 10 is a schematic diagram showing still another embodiment of the wastewater treatment device. [Figure 7] FIG. 7 is a diagram illustrating the operation of the wastewater treatment device shown in FIG. [Figure 8] FIG. 10 is a schematic diagram showing still another embodiment of the wastewater treatment device. [Figure 9] FIG. 9 is a diagram illustrating the operation of the wastewater treatment device shown in FIG. [Figure 10] FIG. 10 is a schematic diagram showing still another embodiment of the wastewater treatment device. [Figure 11] 11 is a diagram illustrating the operation of the wastewater treatment device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram showing one embodiment of a wastewater treatment device. As shown in Fig. 1, the wastewater treatment device includes a wastewater treatment tank 5 that treats wastewater using bacteria supported on a carrier 1, a first solid-liquid separation device 6 that separates the wastewater from the carrier 1, a first transfer device 7 that extracts a portion of the carrier 1 and a portion of the wastewater from the wastewater treatment tank 5 and transfers them to the first solid-liquid separation device 6, a carrier treatment tank 8 that treats the carrier 1 separated by the first solid-liquid separation device 6 with a chemical, a second solid-liquid separation device 10 that separates the chemical from the carrier 1, and a second transfer device 12 that extracts a portion of the carrier 1 and a portion of the chemical from the carrier treatment tank 8 and transfers them to the second solid-liquid separation device 10.

[0016] The wastewater to be treated flows into the wastewater treatment tank 5. The wastewater treated by the bacteria carried on the carriers 1 in the wastewater treatment tank 5, i.e., the treated water, is discharged from the wastewater treatment tank 5. Examples of the wastewater to be treated include sewage, dehydrated separated liquid of anaerobic digestion sludge of sewage sludge, human waste and septic tank sludge, concentrated separated liquid and dehydrated separated liquid of human waste and septic tank sludge, dehydrated separated liquid of methane fermentation sludge of organic waste, and industrial wastewater.

[0017] Examples of the carrier 1 that can be used include gel-based carriers and plastic-based carriers. Examples of agents for treating the carrier 1 include acids (sulfuric acid, hydrochloric acid), alkalis (caustic soda), and aqueous nitrite solutions (aqueous solutions of nitrites such as sodium nitrite).

[0018] The first solid-liquid separator 6 is located above the carrier treatment tank 8, and the carriers 1 separated by the first solid-liquid separator 6 fall from the first solid-liquid separator 6 into the carrier treatment tank 8 due to their own weight. In the embodiment shown in FIG. 1 , the first solid-liquid separator 6 is located directly above the carrier treatment tank 8, and is disposed on top of the carrier treatment tank 8. The first solid-liquid separator 6 has a first screen 15 that is inclined relative to the vertical direction. The first screen 15 has slits or through-holes and is configured to allow the wastewater to pass through but not the carriers 1 to pass through.

[0019] The mixture of carrier 1 and wastewater is transferred from the wastewater treatment tank 5 to the first solid-liquid separator 6 by the first transfer device 7. The mixture of carrier 1 and wastewater is supplied from the first transfer device 7 onto the first screen 15, where it is separated into carrier 1 and wastewater. The carrier 1 moves downward on the inclined first screen 15 due to its own weight and then falls from the first screen 15 into the carrier treatment tank 8. The first screen 15 can perform solid-liquid separation using gravity without requiring a driving force such as an electric motor. The first screen 15 configured in this manner is less likely to cause the bacteria carried on the surface of the carrier 1 to peel off or the carrier 1 itself to be damaged. In addition, since the carrier 1 separated from the wastewater falls directly into the carrier treatment tank 8 due to its own weight, stress on the carrier 1 is small, preventing the bacteria carried on the surface of the carrier 1 from peeling off or the carrier 1 itself from being damaged.

[0020] The wastewater treatment device is equipped with an agitator 20 that agitates the carrier 1 and chemicals in the carrier treatment tank 8. The agitator 20 is equipped with an agitator blade 21 disposed in the carrier treatment tank 8 and a rotating device 22 that rotates the agitator blade 21. While the carrier 1 and chemicals are agitated by the agitator 20 in the carrier treatment tank 8, the carrier 1 is treated with the chemicals.

[0021] The wastewater treatment device is provided with a wastewater return passage 24 that returns the wastewater separated by the first solid-liquid separation device 6 to the wastewater treatment tank 5. The wastewater return passage 24 extends from the first solid-liquid separation device 6 to the wastewater treatment tank 5. The wastewater separated from the carrier 1 by the first screen 15 is returned to the wastewater treatment tank 5 through the wastewater return passage 24.

[0022] According to this embodiment, the wastewater extracted from the wastewater treatment tank 5 by the first transfer device 7 is returned to the wastewater treatment tank 5 from the first solid-liquid separator 6. Therefore, in the carrier treatment tank 8, the chemical is not used on the wastewater, but only on the carrier 1. As a result, the amount of chemical required to treat the carrier 1 can be reduced. Furthermore, since the carrier treatment tank 8 does not need to receive wastewater, the volume of the carrier treatment tank 8 can be reduced.

[0023] The second solid-liquid separator 10 is located above the wastewater treatment tank 5, and the carrier 1 separated by the second solid-liquid separator 10 falls from the second solid-liquid separator 10 into the wastewater treatment tank 5 due to its own weight. In the embodiment shown in FIG. 1 , the second solid-liquid separator 10 is located directly above the wastewater treatment tank 5, and is disposed on top of the wastewater treatment tank 5. The second solid-liquid separator 10 has a second screen 25 that is inclined relative to the vertical direction. The second screen 25 has slits or through holes and is configured to allow the passage of the chemical agent but not the passage of the carrier 1.

[0024] The mixture of carrier 1 and chemical is transferred from carrier treatment tank 8 to second solid-liquid separator 10 by second transfer device 12. The mixture of carrier 1 and chemical is fed from second transfer device 12 onto second screen 25, where it is separated into carrier 1 and chemical. Carrier 1 moves downward on the tilted second screen 25 due to its own weight and then falls from the second screen 25 into wastewater treatment tank 5. The second screen 25 performs solid-liquid separation by gravity, without requiring a driving force such as an electric motor. The second screen 25 configured in this manner is less likely to cause detachment of bacteria supported on the surface of carrier 1 or damage to carrier 1 itself. Additionally, since carrier 1 separated from the chemical falls directly into wastewater treatment tank 5 due to its own weight, stress on carrier 1 is small, preventing detachment of bacteria supported on the surface of carrier 1 or damage to carrier 1 itself.

[0025] The wastewater treatment device is provided with a chemical return passage 26 that returns the chemical separated by the second solid-liquid separation device 10 to the carrier treatment tank 8. The chemical return passage 26 extends from the second solid-liquid separation device 10 to the carrier treatment tank 8. The chemical separated from the carrier 1 by the second screen 25 is returned to the carrier treatment tank 8 through the chemical return passage 26.

[0026] According to this embodiment, the chemical agent extracted from the carrier treatment tank 8 by the second transfer device 12 is returned to the carrier treatment tank 8 from the second solid-liquid separator 10. Therefore, the amount of chemical agent in the carrier treatment tank 8 is kept constant, and there is no need to replenish the chemical agent. As a result, the amount of chemical agent required for treatment of the carrier 1 can be reduced. Furthermore, since the chemical agent does not flow into the wastewater treatment tank 5, the chemical agent does not affect the treatment of wastewater in the wastewater treatment tank 5.

[0027] In this embodiment, the first transfer device 7 and the second transfer device 12 each include an air lift pump. More specifically, the first transfer device 7 includes a first lift pipe 31 extending from the wastewater treatment tank 5 to the first solid-liquid separation device 6, and a first air lift pump equipped with a first air injection pipe 32 that injects air into the first lift pipe 31. The first air injection pipe 32 is connected to the first lift pipe 31 within the wastewater treatment tank 5. When air is injected into the first lift pipe 31 from the first air injection pipe 32, a portion of the wastewater and a portion of the carrier 1 are transferred through the first lift pipe 31 to the first solid-liquid separation device 6 by the gas-liquid two-phase flow.

[0028] Similarly, the second transfer device 12 is composed of a second lift pipe 35 extending from the carrier treatment tank 8 to the second solid-liquid separation device 10, and a second air lift pump equipped with a second air injection pipe 36 that injects air into the second lift pipe 35. The second air injection pipe 36 is connected to the second lift pipe 35 inside the carrier treatment tank 8. When air is injected from the second air injection pipe 36 into the second lift pipe 35, a portion of the chemical and a portion of the carrier 1 are transferred through the second lift pipe 35 to the second solid-liquid separation device 10 by the gas-liquid two-phase flow.

[0029] Air lift pumps do not have rotating impellers and use air pressure as their driving force. Therefore, the first transfer device 7 and the second transfer device 12 equipped with air lift pumps are less likely to cause the bacteria carried on the surface of the carrier 1 to peel off or damage the carrier 1 itself.

[0030] In one embodiment, as shown in FIG. 2, the first transfer device 7 and the second transfer device 12 may be equipped with uniaxial screw pumps 40, 41 instead of air lift pumps. The uniaxial screw pumps 40, 41 are provided in the first lift pipe 31 and the second lift pipe 35. The uniaxial screw pumps 40, 41 are pumps that transfer fluid by rotating a screw rotor within a housing. For example, a Mono Pump available from Heishin Equipment Co., Ltd. can be used as such uniaxial screw pumps 40, 41.

[0031] Fig. 3 is a schematic diagram showing another embodiment of the wastewater treatment apparatus. The configuration and operation of this embodiment, which are not particularly described, are the same as those of the embodiment described with reference to Fig. 1, and therefore, redundant description will be omitted. As shown in Fig. 3, in this embodiment, the first solid-liquid separation device 6 is located directly above the wastewater treatment tank 5, and is disposed on top of the wastewater treatment tank 5. The wastewater treatment apparatus is provided with a first carrier transfer passage 45 that transfers the carrier 1 separated by the first solid-liquid separation device 6 to the carrier treatment tank 8. The first carrier transfer passage 45 extends from the first solid-liquid separation device 6 to the carrier treatment tank 8.

[0032] The mixture of carrier 1 and wastewater is transferred from wastewater treatment tank 5 to first solid-liquid separator 6 by first transfer device 7. The mixture of carrier 1 and wastewater is supplied from first transfer device 7 onto first screen 15, where it is separated into carrier 1 and wastewater. The wastewater that passes through first screen 15 falls directly into wastewater treatment tank 5.

[0033] The carrier 1 moves downward on the inclined first screen 15 due to its own weight, and is further sent to the carrier treatment tank 8 through the first carrier transfer passage 45. The first carrier transfer passage 45 may be inclined so that the carrier 1 moves toward the carrier treatment tank 8 due to its own weight, or may be provided with a conveyor for transporting the carrier 1. In one embodiment, the wastewater treatment tank 5 and the carrier treatment tank 8 may be arranged adjacent to each other, and the carrier 1 may drop directly from the first solid-liquid separator 6 into the carrier treatment tank 8. In this case, the first carrier transfer passage 45 is omitted.

[0034] The second solid-liquid separation device 10 is located directly above the carrier treatment tank 8, and is disposed on top of the carrier treatment tank 8. The wastewater treatment device is provided with a second carrier transfer passage 46 that transfers the carrier 1 separated by the second solid-liquid separation device 10 to the wastewater treatment tank 5. The second carrier transfer passage 46 extends from the second solid-liquid separation device 10 to the wastewater treatment tank 5.

[0035] The mixture of carrier 1 and chemicals is transferred from carrier treatment tank 8 to second solid-liquid separator 10 by second transfer device 12. The mixture of carrier 1 and chemicals is supplied from second transfer device 12 onto second screen 25, where it is separated into carrier 1 and chemicals. The chemicals that pass through second screen 25 drop directly into carrier treatment tank 8.

[0036] The carrier 1 moves downward on the inclined second screen 25 under its own weight, and is further sent to the wastewater treatment tank 5 through the second carrier transfer passage 46. The second carrier transfer passage 46 may be inclined so that the carrier 1 moves toward the wastewater treatment tank 5 under its own weight, or may be provided with a conveyor for transporting the carrier 1. In one embodiment, the wastewater treatment tank 5 and the carrier treatment tank 8 may be arranged adjacent to each other, and the carrier 1 may drop directly from the second solid-liquid separator 10 into the wastewater treatment tank 5. In this case, the second carrier transfer passage 46 is omitted.

[0037] The single screw pumps 40 and 41 described with reference to FIG. 2 are applicable to the embodiment described with reference to FIG.

[0038] Fig. 4 is a schematic diagram showing yet another embodiment of a wastewater treatment device. The configuration and operation of this embodiment that are not particularly described are the same as those of the embodiment described with reference to Fig. 1, and therefore redundant description will be omitted. As shown in Fig. 4, the wastewater treatment device of this embodiment includes a common solid-liquid separation device 50 that serves as both the first solid-liquid separation device 6 and the second solid-liquid separation device 10. The solid-liquid separation device 50 functions as both the first solid-liquid separation device 6 and the second solid-liquid separation device 10 shown in Fig. 1.

[0039] The solid-liquid separation device 50 includes a solid-liquid separation screen 52 and a carrier sorting device 54 that selectively sorts the carrier 1 on the solid-liquid separation screen 52 into either the carrier treatment tank 8 or the wastewater treatment tank 5. In this embodiment, the solid-liquid separation screen 52 is an endless screen belt. The solid-liquid separation screen 52 has slits or holes and is configured to allow the wastewater and chemicals to pass through but not the carrier 1 to pass through.

[0040] The solid-liquid separation screen 52 is disposed horizontally, with both ends of the solid-liquid separation screen 52 located above the wastewater treatment tank 5 and the carrier treatment tank 8, respectively. The outlet of the first transfer device 7 and the outlet of the second transfer device 12 are located above the solid-liquid separation screen 52. The carrier sorting device 54 is equipped with a plurality of rollers 55, 56 that support the solid-liquid separation screen 52, which is an endless screen belt, and a roller rotation device 57 that rotates one of the plurality of rollers 55, 56. When the roller rotation device 57 rotates the roller 55, the entire solid-liquid separation screen 52 rotates.

[0041] The wastewater treatment device further includes a liquid distributor 60 that returns wastewater that has passed through the solid-liquid separation screen 52 to the wastewater treatment tank 5 and returns the chemicals that have passed through the solid-liquid separation screen 52 to the carrier treatment tank 8. The liquid distributor 60 includes a liquid receiver 61 located below the solid-liquid separation screen 52, a liquid return passage 62 connected to the liquid receiver 61, and two flow path switching valves 64, 65 disposed in the liquid return passage 62. The liquid return passage 62 has a main passage 67 connected to the liquid receiver 61 and two branch passages 68, 69 branching off from the main passage 67. The two branch passages 68, 69 extend from the main passage 67 to the wastewater treatment tank 5 and the carrier treatment tank 8, respectively. The two flow path switching valves 64, 65 are attached to the two branch passages 68, 69, respectively.

[0042] 4 , as long as the liquid sorting device 60 is configured to return the wastewater that has passed through the solid-liquid separation screen 52 to the wastewater treatment tank 5 and return the chemical that has passed through the solid-liquid separation screen 52 to the carrier treatment tank 8. In one embodiment, the flow path switching valves 64, 65 may be configured as one three-way valve.

[0043] When the solid-liquid separator 50 functions as the first solid-liquid separator 6, as shown in FIG. 4, the first transfer device 7 extracts a portion of the carrier 1 and a portion of the wastewater from the wastewater treatment tank 5 and transfers them onto the solid-liquid separation screen 52. When the roller rotation device 57 rotates the rollers 55 in one direction, the solid-liquid separation screen 52 moves the carrier 1 toward the carrier treatment tank 8, and the carrier 1 falls into the carrier treatment tank 8. The wastewater that has passed through the solid-liquid separation screen 52 is received in the liquid receiver 61 and is then returned from the liquid receiver 61 to the wastewater treatment tank 5 through a liquid return passage 62. A flow path switching valve 64 provided in a branch passage 68 extending to the wastewater treatment tank 5 is opened, while a flow path switching valve 65 provided in a branch passage 69 extending to the carrier treatment tank 8 is closed.

[0044] When the solid-liquid separator 50 functions as the second solid-liquid separator 10, as shown in FIG. 5 , the second transfer device 12 extracts a portion of the carrier 1 and a portion of the chemical from the carrier treatment tank 8 and transfers them onto the solid-liquid separation screen 52. When the roller rotation device 57 rotates the rollers 55 in the opposite direction, the solid-liquid separation screen 52 moves the carrier 1 toward the wastewater treatment tank 5, and the carrier 1 falls into the wastewater treatment tank 5. The chemical that passes through the solid-liquid separation screen 52 is received in the liquid receiver 61 and is returned from the liquid receiver 61 to the carrier treatment tank 8 through the liquid return passage 62. The flow path switching valve 64 provided in the branch passage 68 extending to the wastewater treatment tank 5 is closed, while the flow path switching valve 65 provided in the branch passage 69 extending to the carrier treatment tank 8 is opened.

[0045] Thus, according to this embodiment, the solid-liquid separator 50 can function as both the first solid-liquid separator 6 that separates wastewater from the carrier 1 and the second solid-liquid separator 10 that separates the chemicals from the carrier 1. Since there is no need to provide two solid-liquid separators, the overall size of the wastewater treatment device can be reduced.

[0046] The solid-liquid separator 50 of this embodiment, which is equipped with the solid-liquid separation screen 52 and the carrier distributing device 54, is a carrier conveyor that selectively moves the carrier 1 to either the wastewater treatment tank 5 or the carrier treatment tank 8 while separating the carrier 1 from the liquid. However, the configuration of the solid-liquid separator 50 is not limited to the embodiment shown in Fig. 4, as long as it is configured to be able to selectively distribute the carrier 1 to either the wastewater treatment tank 5 or the carrier treatment tank 8 while separating the carrier 1 from the liquid.

[0047] Fig. 6 is a schematic diagram showing yet another embodiment of the wastewater treatment device. The configuration and operation of this embodiment, which are not particularly described, are the same as those of the embodiment described with reference to Fig. 4, and therefore redundant description will be omitted. In this embodiment, the solid-liquid separator 50 includes a cylindrical solid-liquid separation screen 80 and a carrier sorting device 81 that selectively sorts the carriers 1 on the solid-liquid separation screen 80 into either the carrier treatment tank 8 or the wastewater treatment tank 5.

[0048] The solid-liquid separation screen 80 has slits or through holes and is configured to allow the passage of wastewater and chemicals but not the passage of the carrier 1. Both ends of the solid-liquid separation screen 80 are located above the wastewater treatment tank 5 and the carrier treatment tank 8, respectively. The outlet of the first transfer device 7 and the outlet of the second transfer device 12 are located above the solid-liquid separation screen 80. The carrier sorting device 81 includes a screw 83 surrounded by the cylindrical solid-liquid separation screen 80, and a screw rotation device 84 that rotates the screw 83.

[0049] When the solid-liquid separator 50 functions as the first solid-liquid separator 6, as shown in Figure 6, the first transfer device 7 extracts a portion of the carrier 1 and a portion of the wastewater from the wastewater treatment tank 5 and transfers them onto the solid-liquid separation screen 80. When the screw rotation device 84 rotates the screw 83 in one direction, the screw 83 moves the carrier 1 on the solid-liquid separation screen 80 toward the carrier treatment tank 8, and the carrier 1 drops into the carrier treatment tank 8. The wastewater that has passed through the solid-liquid separation screen 80 is received in the liquid receiver 61 and is then returned from the liquid receiver 61 to the wastewater treatment tank 5 through the liquid return passage 62. A flow path switching valve 64 provided in a branch passage 68 extending to the wastewater treatment tank 5 is opened, while a flow path switching valve 65 provided in a branch passage 69 extending to the carrier treatment tank 8 is closed.

[0050] When the solid-liquid separator 50 functions as the second solid-liquid separator 10, as shown in FIG. 7, the second transfer device 12 extracts a portion of the carrier 1 and a portion of the chemical from the carrier treatment tank 8 and transfers them onto the solid-liquid separation screen 80. When the screw rotation device 84 rotates the screw 83 in the opposite direction, the screw 83 moves the carrier 1 on the solid-liquid separation screen 80 toward the wastewater treatment tank 5, and the carrier 1 drops into the wastewater treatment tank 5. The chemical that passes through the solid-liquid separation screen 80 is received in the liquid receiver 61 and is returned from the liquid receiver 61 to the carrier treatment tank 8 through the liquid return passage 62. The flow path switching valve 64 provided in the branch passage 68 extending to the wastewater treatment tank 5 is closed, while the flow path switching valve 65 provided in the branch passage 69 extending to the carrier treatment tank 8 is opened.

[0051] Fig. 8 is a schematic diagram showing yet another embodiment of the wastewater treatment device. The configuration and operation of this embodiment, which are not particularly described, are the same as those of the embodiment described with reference to Fig. 4, and therefore redundant description will be omitted. In this embodiment, the solid-liquid separator 50 includes a planar solid-liquid separation screen 90 and a carrier sorting device 91 that selectively sorts the carriers 1 on the solid-liquid separation screen 90 into either the carrier treatment tank 8 or the wastewater treatment tank 5.

[0052] The carrier sorting device 91 is equipped with a tilting actuator 93 that tilts the entire solid-liquid separation screen 90. The tilting actuator 93 is connected to a rotating shaft 94 fixed to the solid-liquid separation screen 90, and is configured to tilt the entire solid-liquid separation screen 90 by rotating the rotating shaft 94 by a predetermined angle. Both ends of the solid-liquid separation screen 90 are located above the wastewater treatment tank 5 and the carrier treatment tank 8, respectively.

[0053] When the solid-liquid separator 50 functions as the first solid-liquid separator 6, as shown in Fig. 8, the first transfer device 7 extracts a portion of the carrier 1 and a portion of the wastewater from the wastewater treatment tank 5 and transfers them onto the solid-liquid separation screen 90. When the tilting actuator 93 tilts the solid-liquid separation screen 90 in one direction, the carrier 1 on the solid-liquid separation screen 90 moves under its own weight toward the carrier treatment tank 8 and drops into the carrier treatment tank 8. The wastewater that has passed through the solid-liquid separation screen 90 is received in the liquid receiver 61 and is then returned from the liquid receiver 61 to the wastewater treatment tank 5 through the liquid return passage 62. A flow path switching valve 64 provided in a branch passage 68 extending to the wastewater treatment tank 5 is opened, while a flow path switching valve 65 provided in a branch passage 69 extending to the carrier treatment tank 8 is closed.

[0054] When the solid-liquid separator 50 functions as the second solid-liquid separator 10, as shown in Figure 9, the second transfer device 12 extracts a portion of the carrier 1 and a portion of the chemical from the carrier treatment tank 8 and transfers them onto the solid-liquid separation screen 90. When the tilting actuator 93 tilts the solid-liquid separation screen 90 in the opposite direction, the carrier 1 on the solid-liquid separation screen 90 moves under its own weight toward the wastewater treatment tank 5 and drops into the wastewater treatment tank 5. The chemical that passes through the solid-liquid separation screen 90 is received in the liquid receiver 61 and is returned from the liquid receiver 61 to the carrier treatment tank 8 through the liquid return passage 62. The flow path switching valve 64 provided in the branch passage 68 extending to the wastewater treatment tank 5 is closed, while the flow path switching valve 65 provided in the branch passage 69 extending to the carrier treatment tank 8 is opened.

[0055] Figure 10 is a schematic diagram showing yet another embodiment of a wastewater treatment device. The configuration and operation of this embodiment, unless otherwise specified, are the same as those of the embodiment described with reference to Figure 4, and therefore redundant description will be omitted. In this embodiment, a solid-liquid separation device 50 includes a solid-liquid separation screen 100 tilted relative to the vertical direction and a carrier sorting device 101 that selectively sorts the carrier 1 separated from the wastewater or chemicals by the solid-liquid separation screen 100 into either the carrier treatment tank 8 or the wastewater treatment tank 5. The solid-liquid separation screen 100 has slits or through-holes and is configured to allow the wastewater and chemicals to pass through but not the carrier 1.

[0056] The carrier sorting device 101 includes a carrier receiver 105 disposed below the solid-liquid separation screen 100, a first carrier guide passage 107 and a second carrier guide passage 108 connected to the carrier receiver 105, a first gate 111 for opening and closing the entrance to the first carrier guide passage 107, and a second gate 112 for opening and closing the entrance to the second carrier guide passage 108. The first gate 111 and the second gate 112 are each connected to actuators (not shown), which operate the first gate 111 and the second gate 112 independently. The outlets of the first transfer device 7 and the second transfer device 12 are located above the solid-liquid separation screen 100. The outlet of the first carrier guide passage 107 is located above the wastewater treatment tank 5, and the outlet of the second carrier guide passage 108 is located above the carrier treatment tank 8.

[0057] The main passage 67 of the liquid distributing device 60 is located below the solid-liquid separation screen 100, and is configured so that wastewater or chemicals that have passed through the solid-liquid separation screen 100 flow into the main passage 67. More specifically, a liquid guide 115 is disposed below the solid-liquid separation screen 100, and the wastewater or chemicals that have passed through the solid-liquid separation screen 100 are received in the liquid guide 115. The main passage 67 is connected to the liquid guide 115, and the wastewater or chemicals received in the liquid guide 115 flow from the liquid guide 115 into the main passage 67. The other configurations of the liquid distributing device 60 are the same as those of the above-described embodiment, so duplicated explanations will be omitted.

[0058] When the solid-liquid separator 50 functions as the first solid-liquid separator 6, as shown in FIG. 10, the first transfer device 7 extracts a portion of the carrier 1 and a portion of the wastewater from the wastewater treatment tank 5 and transfers them onto the solid-liquid separation screen 100. The carrier 1 on the solid-liquid separation screen 100 falls into the carrier receiver 105 due to its own weight. The first gate 111 is closed, and the second gate 112 is opened. Therefore, the carrier 1 is transferred to the carrier treatment tank 8 through the second carrier guide passage 108. The second carrier guide passage 108 may be inclined so that the carrier 1 moves toward the carrier treatment tank 8 due to its own weight, or may be provided with a conveyor for transferring the carrier 1.

[0059] The wastewater that has passed through the solid-liquid separation screen 100 is received by the liquid guide 115 and is then returned from the liquid guide 115 to the wastewater treatment tank 5 through the liquid return passage 62. The flow path switching valve 64 provided in the branch passage 68 extending to the wastewater treatment tank 5 is opened, while the flow path switching valve 65 provided in the branch passage 69 extending to the carrier treatment tank 8 is closed.

[0060] When the solid-liquid separator 50 functions as the second solid-liquid separator 10, as shown in FIG. 11 , the second transfer device 12 extracts a portion of the carrier 1 and a portion of the chemical from the carrier treatment tank 8 and transfers them onto the solid-liquid separation screen 100. The carrier 1 on the solid-liquid separation screen 100 falls into the carrier receiver 105 due to its own weight. The first gate 111 is opened, and the second gate 112 is closed. Therefore, the carrier 1 is transferred to the wastewater treatment tank 5 through the first carrier guide passage 107. The first carrier guide passage 107 may be inclined so that the carrier 1 moves toward the wastewater treatment tank 5 due to its own weight, or may be provided with a conveyor for transferring the carrier 1.

[0061] The chemical that has passed through the solid-liquid separation screen 100 is received by the liquid guide 115 and is then returned from the liquid guide 115 to the carrier treatment tank 8 through the liquid return passage 62. The flow path switching valve 64 provided in the branch passage 68 extending to the wastewater treatment tank 5 is closed, while the flow path switching valve 65 provided in the branch passage 69 extending to the carrier treatment tank 8 is opened.

[0062] The solid-liquid separation screen, the carrier distribution device, and the liquid distribution device are not limited to the above-described embodiments, as long as they can perform their intended functions.

[0063] The above-described embodiments have been described for the purpose of enabling a person of ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments would be obvious to a person skilled in the art, and the technical concept of the present invention may be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope in accordance with the technical concept defined by the claims. [Explanation of symbols]

[0064] 1. Carrier 5 Wastewater treatment tank 6 1st solid-liquid separator 7 First transfer device 8. Carrier treatment tank 10 Second solid-liquid separator 12 Second transfer device 15 Screen 1 20 Stirring device 21 Stirring blade 22 Rotating device 24 Wastewater return passage 25 Screen 2 26 Drug return passage 31 No. 1 Lift Pipe 32 First air injection pipe 35 Second Lift Pipe 36 Second air injection pipe 40,41 Single screw pump 45 First carrier transfer passage 46 Second carrier transfer passage 50 Solid-liquid separator 52 Solid-liquid separation screen 54 Carrier sorting device 55,56 Roller 57 Roller rotation device 60 Liquid sorting device 61 Liquid receiver 62 Liquid return passage 64,65 Flow path switching valve 67 Main aisle 68,69 Branch passage 80 Solid-liquid separation screen 81 Carrier sorting device 83 Screw 84 Screw Rotation Device 90 Solid-liquid separation screen 91 Carrier sorting device 93 Tilting Actuator 94 Rotational Axis 100 Solid-liquid separation screen 101 Carrier sorting device 105 Carrier receiver 107 First carrier guide passage 108 Second carrier guide passage 111 Gate 1 112 Gate 2 115 Liquid Guide

Claims

1. a wastewater treatment tank for treating wastewater using bacteria carried on a carrier; a solid-liquid separator for separating the carrier from the wastewater and the chemical; a first transfer device that extracts a portion of the carrier and a portion of the wastewater from the wastewater treatment tank and transfers them to the solid-liquid separation device; a carrier treatment tank in which the carrier separated from the wastewater by the solid-liquid separation device is treated with the chemical; The wastewater treatment device further comprises a second transfer device that extracts a part of the carrier and a part of the chemical from the carrier treatment tank and transfers them to the solid-liquid separation device.

2. 2. The wastewater treatment device according to claim 1, wherein the solid-liquid separation devices include a first solid-liquid separation device that separates the carrier from the wastewater, and a second solid-liquid separation device that separates the carrier from the chemicals.

3. the first solid-liquid separator is located above the carrier treatment tank so that the carriers separated by the first solid-liquid separator fall from the first solid-liquid separator into the carrier treatment tank; The wastewater treatment device according to claim 2 , further comprising a wastewater return passage for returning the wastewater separated by the first solid-liquid separator to the wastewater treatment tank.

4. the second solid-liquid separator is located above the wastewater treatment tank so that the carriers separated by the second solid-liquid separator fall from the second solid-liquid separator into the wastewater treatment tank; The wastewater treatment device according to claim 2 , further comprising a chemical return passage for returning the chemical separated by the second solid-liquid separator to the carrier treatment tank.

5. the first solid-liquid separator is located above the wastewater treatment tank so that the wastewater separated by the first solid-liquid separator falls from the first solid-liquid separator into the wastewater treatment tank; The wastewater treatment device according to claim 2 , further comprising a first carrier transfer passage for transferring the carrier separated by the first solid-liquid separator to the carrier treatment tank.

6. the second solid-liquid separator is located above the carrier treatment tank so that the chemicals separated by the second solid-liquid separator fall from the second solid-liquid separator into the carrier treatment tank; The wastewater treatment device according to claim 2 , further comprising a second carrier transfer passage for transferring the carrier separated by the second solid-liquid separator to the wastewater treatment tank.

7. The solid-liquid separation device is a solid-liquid separation screen; 2. The wastewater treatment device according to claim 1, further comprising a carrier sorting device that selectively sorts the carrier separated from the wastewater or the chemical by the solid-liquid separation screen into either the carrier treatment tank or the wastewater treatment tank.

8. The wastewater treatment device according to claim 7, further comprising a liquid sorting device that returns the wastewater that has passed through the solid-liquid separation screen to the wastewater treatment tank and returns the chemical that has passed through the solid-liquid separation screen to the carrier treatment tank.

9. The wastewater treatment device of claim 1 , wherein the first transfer device and the second transfer device each comprise an air lift pump.

10. The wastewater treatment device of claim 1 , wherein the first transfer device and the second transfer device each comprise a single screw pump.

11. The wastewater treatment device according to claim 1 , wherein the carrier is a gel-based carrier.

12. The wastewater treatment device according to claim 1 , wherein the carrier is a plastic carrier.

13. The wastewater is treated in a wastewater treatment tank by the bacteria carried on the carrier. A portion of the carrier and a portion of the wastewater are extracted from the wastewater treatment tank and transferred to a solid-liquid separation device; The wastewater and the carrier are separated by the solid-liquid separator; The separated wastewater is returned to the wastewater treatment tank, and the separated carrier is transferred to a carrier treatment tank; treating the carrier with a chemical in the carrier treatment tank; A portion of the carrier and a portion of the chemical are extracted from the carrier treatment tank and transferred to the solid-liquid separation device; The drug and the carrier are separated by the solid-liquid separator; The separated chemicals are returned to the carrier treatment tank, and the separated carriers are transferred to the wastewater treatment tank.

14. The wastewater treatment method according to claim 13, wherein the carrier is a gel-based carrier.

15. The wastewater treatment method according to claim 13, wherein the carrier is a plastic carrier.

Images