Wastewater treatment equipment

Abstract

Separating solids when treating wastewater. [Solution] The wastewater treatment device includes multiple water treatment tanks, including a first filtration tank, an aerobic treatment tank located downstream of the first filtration tank, and a second filtration tank located downstream of the aerobic treatment tank, and the aerobic treatment tank has a fixed bed. Alternatively, the wastewater treatment system includes multiple water treatment tanks, each including a settling tank and a storage tank, an agitation device configured to agitate water in the settling tank, a transfer device configured to transfer water from the settling tank to the storage tank, and a controller configured to control the agitation device and the transfer device. The controller is configured to perform specific processes, including an agitation process in which the agitation device agitates the water in the settling tank, and a transfer process in which the transfer device transfers water containing solids from the settling tank to the storage tank after the agitation process.

Description

[Technical Field]

[0001] The present specification relates to a wastewater treatment device. [Background technology]

[0002] Conventionally, wastewater from households and the like has been treated by wastewater treatment devices. Wastewater treatment devices may have various water treatment tanks for separating solids from water. For example, wastewater treatment devices may have a filtration tank configured to filter solids or a settling tank configured to settle solids. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-119562 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-159290 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when treating wastewater, separation of solids is not easy, and there is room for improvement.

[0005] This specification discloses a technique for separating solids when treating wastewater. [Means for solving the problem]

[0006] The techniques disclosed in this specification can be implemented in the following application examples.

[0007] [Application example 1] A wastewater treatment device, The system comprises a plurality of water treatment tanks including a first filtration tank, an aerobic treatment tank arranged downstream of the first filtration tank, and a second filtration tank arranged downstream of the aerobic treatment tank, The aerobic treatment tank has a fixed bed. Wastewater treatment equipment.

[0008] With this configuration, the aerobic treatment tank is located downstream of the first filtration tank, reducing the amount of solids flowing into the aerobic treatment tank. Furthermore, because the aerobic treatment tank has a fixed bed, the possibility of the solids flowing into the aerobic treatment tank being crushed is reduced. Because the possibility of the solids being crushed is reduced, the second filtration tank can easily capture the solids. In this way, the wastewater treatment device can properly separate the solids from the water.

[0009] [Application example 2] The wastewater treatment device according to Application Example 1, The plurality of water treatment tanks include: A first target tank which is either the aerobic treatment tank or a water treatment tank arranged downstream of the aerobic treatment tank; a second target tank which is any one of the first filtration tank, a water treatment tank arranged upstream of the first filtration tank, a storage tank for storing solids, and an anaerobic treatment tank; Including, The wastewater treatment device includes a target transfer device configured to transfer water from the first target tank to the second target tank. Wastewater treatment equipment.

[0010] According to this configuration, the object transfer device can transfer solids together with water from the aerobic treatment tank or the water treatment tank arranged downstream of the aerobic treatment tank to the second object tank.

[0011] [Application example 3] The wastewater treatment device according to Application Example 1 or 2, The plurality of water treatment tanks includes a disinfection tank subsequent to the second filtration tank. Wastewater treatment equipment.

[0012] According to this configuration, the wastewater treatment device can be made smaller than when a separate water treatment tank is provided between the second filtration tank and the disinfection tank.

[0013] [Application example 4] The wastewater treatment device according to any one of Application Examples 1 to 3, The first filtration tank has a first filtration section including a plurality of carriers, The second filtration tank has a second filtration section including a plurality of carriers, The carrier of the second filtration unit is the same as the carrier of the first filtration unit. Wastewater treatment equipment.

[0014] If the carriers used in the first and second filtration units are different, the wrong carrier may be used to manufacture the first or second filtration unit. With the above configuration, such a problem can be avoided.

[0015] [Application example 5] The wastewater treatment device according to any one of Application Examples 1 to 4, The first filtration tank has a first filtration section including a plurality of carriers, The second filtration tank has a second filtration section including a plurality of carriers, The volume of the plurality of carriers in the second filtration section is larger than the volume of the plurality of carriers in the first filtration section. Wastewater treatment equipment.

[0016] According to this configuration, the first filtration tank can capture relatively large solid matter, and the second filtration tank can capture relatively small solid matter, so the wastewater treatment device can separate the solid matter appropriately.

[0017] [Application Example 6] The wastewater treatment device according to Application Example 4 or 5, The top of the first filtration tank is open, The specific gravity of the carrier of the first filtration section is greater than 1, The top of the second filtration tank is open, The specific gravity of the carrier of the second filtration section is greater than 1. Wastewater treatment equipment.

[0018] With this configuration, the tops of the first and second filtration tanks are open, which reduces the complexity of manufacturing the first and second filtration tanks. Also, because the specific gravities of the carriers in the first and second filtration units are greater than 1, the possibility of the carriers leaking out from the top of the first and second filtration tanks is reduced.

[0019] [Application Example 7] The wastewater treatment device according to any one of Application Examples 1 to 6, a first transfer device configured to simultaneously transfer water from the first filtration tank to a water treatment tank different from the first filtration tank and transfer water from the second filtration tank to a water treatment tank different from the second filtration tank; an agitation device configured to agitate the water in the first filtration tank and the water in the second filtration tank at the same time; A wastewater treatment device comprising:

[0020] This configuration can reduce the amount of solid matter in the first filtration tank and the amount of solid matter in the second filtration tank, and can also reduce the complexity of the configuration of the wastewater treatment device.

[0021] [Application Example 8] The wastewater treatment device according to Application Example 7, The wastewater treatment device has a blower pipe which is a pipe to be connected to a blower, The first transfer device a first air lift pump having a first suction port disposed in the first filtration tank; a second air lift pump having a second suction port disposed in the second filtration tank; a pump connecting pipe that connects the first air lift pump and the second air lift pump; a first connecting pipe that connects the blower pipe and the pump connecting pipe; a first valve provided on a flow path of the first connecting pipe; and The stirring device is a first air diffuser disposed in the first filtration tank; a second air diffuser disposed in the second filtration tank; an aeration connection pipe that connects the first aeration device and the second aeration device; a second connecting pipe that connects the blower pipe and the aeration connecting pipe; a second valve provided on a flow path of the second connecting pipe; A wastewater treatment device comprising:

[0022] With this configuration, the first valve and the second valve can easily control the transfer of water from the first filtration tank and the second filtration tank, and the agitation of the water in the first filtration tank and the water in the second filtration tank.

[0023] [Application Example 9] The wastewater treatment device according to any one of Application Examples 1 to 6, a first air lift pump configured to transfer water from the first filtration tank to a water treatment tank different from the first filtration tank; a second air lift pump configured to transfer water from the second filtration tank to a water treatment tank different from the second filtration tank; a first air diffuser configured to agitate the water in the first filtration tank; a second air diffuser configured to agitate the water in the second filtration tank; a blower pipe which is a pipe to be connected to a blower; a first connecting pipe connecting the blower pipe and the first air lift pump; a first valve provided on a flow path of the first connecting pipe; a second connecting pipe connecting the blower pipe and the second air lift pump; a second valve provided on a flow path of the second connecting pipe; a third connecting pipe connecting the blower pipe and the first air diffuser; a third valve provided on a flow path of the third connecting pipe; a fourth connecting pipe connecting the blower pipe and the second air diffuser; a fourth valve provided on a flow path of the fourth connecting pipe; A wastewater treatment device comprising:

[0024] With this configuration, the four valves can easily control the transfer of water from the first filtration tank, the transfer of water from the second filtration tank, the agitation of water in the first filtration tank, and the agitation of water in the second filtration tank.

[0025] [Application Example 10] A wastewater treatment system comprising: The wastewater treatment device according to any one of Application Examples 1 to 9, A control unit; Equipped with The plurality of water treatment tanks include: a settling tank disposed upstream of the first filtration tank, the settling tank configured to settle solids without filtering the solids; a reservoir configured to store solids; Including, The wastewater treatment device comprises: a settling tank agitator configured to agitate the water in the settling tank; a second transfer device configured to transfer water from the settling tank to the reservoir; Equipped with The control unit an agitation process in which the settling tank agitator agitates the water in the settling tank; a transfer process in which, after the stirring process, the second transfer device transfers water containing solids from the settling tank to the storage tank; A wastewater treatment system configured to perform a specific treatment, including:

[0026] According to this configuration, the settled solids and the floating solids in the settling tank are agitated by the agitation process, and then the transfer process is carried out after the agitation process, so that the settled solids and the floating solids can be transferred appropriately.

[0027] [Application Example 11] A wastewater treatment system comprising: a plurality of water treatment tanks including a settling tank configured to settle solids without filtering the solids, and a storage tank configured to store the solids; an agitator configured to agitate the water in the settling tank; a transfer device configured to transfer water from the settling tank to the reservoir; a control unit configured to control the stirring device and the transfer device; Equipped with The control unit a stirring process in which the stirring device stirs the water in the settling tank; a transfer process in which, after the stirring process, the transfer device transfers the water containing solids from the settling tank to the storage tank; A wastewater treatment system configured to perform a specific treatment, including:

[0028] According to this configuration, the settled solids and the floating solids in the settling tank are agitated by the agitation process, and the transfer process is carried out after the agitation process, so that the solids can be separated appropriately.

[0029] [Application Example 12] The wastewater treatment system according to Application Example 11, the transfer device has a suction port located in a lower portion of the settling tank; The specific treatment is a treatment performed after the stirring treatment and before the transfer treatment, and includes a precipitation treatment in which solid matter is precipitated in the settling tank by stopping both the stirring by the stirring device and the transfer by the transfer device. Wastewater treatment system.

[0030] With this configuration, the transfer device can transfer water having a high concentration of solids during the transfer process.

[0031] [Application Example 13] The wastewater treatment system according to Application Example 11 or 12, The control unit is configured to execute the specific process N times (N is an integer equal to or greater than 1) per day. Wastewater treatment system.

[0032] According to this configuration, the amount of solid matter remaining in the settling tank can be reduced compared to when the specific treatment is performed less frequently.

[0033] [Application Example 14] The wastewater treatment system according to Application Example 13, The control unit is configured to allow a user to change the number of times N per day that the specific process is performed. Wastewater treatment system.

[0034] According to this configuration, the user can adjust the number of times N per day that a specific treatment is performed in accordance with the inflow load of the wastewater treatment device.

[0035] [Application Example 15] The wastewater treatment system according to any one of Application Examples 11 to 14, The specific treatment includes a treatment of causing the transfer device to transfer water from the settling tank to the storage tank before the stirring treatment. Wastewater Treatment System

[0036] According to this configuration, the stirring process is performed with the water level in the settling tank lowered by the transfer of water, thereby reducing the possibility of solids overflowing from the settling tank during the stirring process.

[0037] [Application Example 16] The wastewater treatment system according to any one of Application Examples 11 to 15, The plurality of water treatment tanks include a target tank that is either the settling tank or a water treatment tank arranged upstream of the settling tank, The wastewater treatment device has a flow path connecting the storage tank and the target tank. Wastewater treatment system.

[0038] This configuration reduces the possibility of water overflowing from the storage tank to the outside of the wastewater treatment device.

[0039] [Application Example 17] The wastewater treatment system according to any one of Application Examples 11 to 16, The plurality of water treatment tanks includes an aerobic treatment tank located downstream of the settling tank. Wastewater treatment system.

[0040] According to this configuration, since the aerobic treatment tank is located downstream of the settling tank, the amount of solids flowing into the aerobic treatment tank is reduced, allowing the wastewater treatment device to treat the wastewater appropriately.

[0041] The technology disclosed in this specification can be realized in various forms, such as a filtration tank or a sedimentation tank, a wastewater treatment device having a filtration tank or a sedimentation tank, a wastewater treatment method, a control device for a wastewater treatment device, a control method for a wastewater treatment device, a computer program, etc. [Brief explanation of the drawings]

[0042] [Figure 1] 1 is a schematic diagram showing a wastewater treatment device as an embodiment; [Figure 2] FIG. 1 is a schematic diagram of a wastewater treatment system 1000. [Figure 3] 10 is a flowchart illustrating an example of a control process. [Figure 4] 10 is a timing chart showing changes in the state of the water treatment tanks 130-160. [Figure 5] 1A to 1C are schematic diagrams showing the respective states of the water treatment tanks 130 to 160. [Figure 6] 10(A) and 10(B) are schematic diagrams showing the respective states of the water treatment tanks 130-160. [Figure 7] 10 is a flowchart illustrating an example of a schedule determination process. [Figure 8] 10 is a flowchart illustrating an example of a schedule execution process. [Figure 9] FIG. 2 is a schematic diagram of another embodiment of a wastewater treatment system. [Figure 10] 10 is a timing chart showing changes in the state of the water treatment tank 130140160. [Figure 11] FIG. 10 is a schematic diagram showing another embodiment of the wastewater treatment device. [Figure 12] FIG. 1 is a schematic diagram of a wastewater treatment system 1000d according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0043] A. First Example: A1.Device configuration: FIG. 1 is a schematic diagram showing a wastewater treatment device according to one embodiment. The diagram shows a side view of the wastewater treatment device 100. The wastewater treatment device 100 of this embodiment purifies wastewater from households and other sources (such devices are also called "septic tanks"). The wastewater treatment device 100 has a body 200. The body 200 houses an aeration screen 110, a flow rate adjustment tank 120, an impurity removal tank 130, a first filtration tank 140, an aerobic filter bed tank 150, a second filtration tank 160, a disinfection tank 170, a discharge pump tank 180, and a sludge storage tank 190. The body 200 has multiple walls (including partition walls 201-208) that form these water treatment tanks 110-190. The partition walls 201-208 each separate two adjacent water treatment tanks.

[0044] Wastewater that flows into the wastewater treatment device 100 flows into an aeration screen 110. The aeration screen 110 has a screen 111 with an aeration device, which removes large solids. Water that passes through the screen 111 flows into the flow rate adjustment tank 120 through an opening 113 formed in a first partition wall 201 between the water treatment tanks 110 and 120.

[0045] The flow rate adjustment tank 120 is a water treatment tank that adjusts the amount of water per unit time that is transferred to a downstream water treatment tank (here, the impurity removal tank 130). The flow rate adjustment tank 120 has a pump 121 (e.g., an electric pump) and a metering adjustment device 122. The pump 121 transfers water from the flow rate adjustment tank 120 to the metering adjustment device 122. A transfer pipe 123 is connected to the metering adjustment device 122. The metering adjustment device 122 supplies a metered portion of the transferred water to the transfer pipe 123. The transfer pipe 123 transfers water from the metering adjustment device 122 to the impurity removal tank 130. In the embodiment of FIG. 1, a sludge storage tank 190 is disposed between the flow rate adjustment tank 120 and the impurity removal tank 130. The transfer pipe 123 passes through a second partition wall 202 between the water treatment tanks 120 and 190 and a third partition wall 203 between the water treatment tanks 190 and 130. Excess water transferred to the metering adjustment device 122 returns to the flow rate adjustment tank 120. The flow rate adjustment tank 120 is provided with an agitation device (not shown) that agitates the water in the flow rate adjustment tank 120. The agitation device may be, for example, an air diffuser that uses air from a blower (not shown) to discharge air bubbles.

[0046] The impurity removal tank 130 is a water treatment tank that separates solids by settling. Such a water treatment tank is also called a sedimentation tank. Hereinafter, the impurity removal tank 130 will also be referred to as the sedimentation tank 130. The sedimentation tank 130 has an inflow baffle 131, an advection baffle 132, and an aeration device 139. The baffles 131 and 132 are fixed to the walls that form the sedimentation tank 130 (in this embodiment, the inflow baffle 131 is fixed to the third partition wall 203, and the advection baffle 132 is fixed to the fourth partition wall 204 between the water treatment tanks 130 and 140). Water from the transfer pipe 123 flows into the area surrounded by the inflow baffle 131. The inflow baffle 131 moves the water downward and guides it into the sedimentation tank 130. The advection baffle 132 moves the water in the settling tank 130 upward and guides it to the downstream water treatment tank (in this embodiment, the first filtration tank 140). In this embodiment, the water in the area surrounded by the advection baffle 132 flows into the first filtration tank 140 through an opening 133 formed in the fourth partition wall 204. The inflow baffle 131 and the advection baffle 132 prevent the agitation of the water in the settling tank 130 and the short-circuiting of the water passing through the settling tank 130. In the settling tank 130, solids are settled and separated. The aeration device 139 has multiple holes for discharging air bubbles and is located at the bottom of the settling tank 130 (hereinafter, also referred to as the settling tank aeration device 139). The settling tank aeration device 139 is used to agitate the water in the settling tank 130 (details will be described later).

[0047] The first filtration tank 140 is a water treatment tank that filters and separates solids. The first filtration tank 140 has an inflow baffle 141, a first filtration unit 147, a first support unit 146 that supports the first filtration unit 147 from below, and a first air diffuser 149 that is positioned lower than the first support unit 146. The inflow baffle 141 is fixed to a wall (in this embodiment, the fourth partition wall 204) that forms the first filtration tank 140. Water from the opening 133 flows into an area surrounded by the inflow baffle 141. The inflow baffle 141 guides the water to a portion of the first filtration tank 140 that is lower than the first support unit 146. The water moves upward through the first support unit 146 and the first filtration unit 147. The first filtration unit 147 captures solids contained in the water. The water that has passed through the first filtration section 147 flows into the aerobic filter bed tank 150 through an opening 143 formed in the fifth partition wall 205 between the water treatment tanks 140 and 150 .

[0048] The first filtration section 147 includes a plurality of first filtration carriers 148 (also simply referred to as first carriers 148). The first carriers 148 are granular members. In this embodiment, the first carriers 148 are formed of a material containing resin (for example, a material containing polypropylene) and have a cylindrical shape. The first support section 146 is a plate member having a plurality of through holes that are smaller than the first carrier 148. The first support section 146 allows water to pass through but prevents water from passing through the first carrier 148. In this embodiment, the first support section 146 is a net made of a material containing resin (for example, polypropylene, polyethylene, fiber-reinforced plastic (FRP), dicyclopentadiene, etc.). The first support section 146 is fixed to walls (in this embodiment, partition walls 204, 205) that form the first filtration tank 140.

[0049] In this embodiment, the specific gravity of the first carrier 148 is greater than 1. Therefore, the plurality of first carriers 148 descend in the water and are deposited on the first support portion 146. The plurality of first carriers 148 deposited on the first support portion 146 collectively form the first filtration portion 147. When the water in the first filtration tank 140 flows, the first carriers 148 can flow together with the water. For example, the specific gravity of the first carrier 148 is greater than 1.0 and equal to or less than 1.2.

[0050] The first air diffuser 149 has a plurality of holes for discharging air bubbles. The first air diffuser 149 is used to agitate the water and the plurality of first carriers 148 in the first filtration tank 140 (details will be described later). The first filtration tank 140 is not provided with a member (for example, a mesh-like cover member) for preventing the plurality of first carriers 148 from moving upward. In other words, the top of the first filtration tank 140 is open. However, the openings 133 and 143 are provided with a member (for example, a mesh) having a plurality of through-holes smaller than the first carriers 148 for allowing water to pass through and preventing the first carriers 148 from passing through (not shown).

[0051] The aerobic filter bed tank 150 is a water treatment tank that performs aerobic treatment of wastewater using aerobic microorganisms. The aerobic filter bed tank 150 includes a filter bed 158 for retaining aerobic microorganisms and an aeration device 159 positioned lower than the filter bed 158. The filter bed 158 is fixed to the walls that form the aerobic filter bed tank 150 (in this embodiment, the fifth partition wall 205 and the sixth partition wall 206 between the water treatment tanks 150 and 160). In this embodiment, the filter bed 158 is a mesh portion having a three-dimensional mesh structure formed from a resin-containing material (e.g., polypropylene, polyethylene, etc.) and has multiple intertwined wires. Note that the filter bed 158 is not limited to a mesh portion and may include various shapes, such as plate portions. The aeration device 159 has multiple holes for discharging air bubbles. Air is supplied to the aeration device 159 by a blower (not shown). The air bubbles discharged from the air diffuser 159 agitate the water in the aerobic filter bed tank 150 and supply oxygen to the water. Aerobic microorganisms attached to the filter bed 158 use the oxygen to perform aerobic treatment. Hereinafter, the air diffuser 159 will also be referred to as the aerobic air diffuser 159. The aerobically treated water flows into the second filtration tank 160 through the opening 153 formed in the sixth partition wall 206.

[0052] The second filtration tank 160 is a water treatment tank that filters and separates solids. The configuration of the second filtration tank 160 is similar to that of the first filtration tank 140. The second filtration tank 160 includes an inflow baffle 161, a second filtration unit 167, a second support unit 166 that supports the second filtration unit 167 from below, and a second air diffuser 169 that is positioned lower than the second support unit 166. The inflow baffle 161 is fixed to a wall (in this embodiment, the sixth partition wall 206) that forms the second filtration tank 160. Water from the opening 153 flows into the area surrounded by the inflow baffle 161. The inflow baffle 161 guides the water to a portion of the second filtration tank 160 that is lower than the second support unit 166. The water moves upward through the second support unit 166 and the second filtration unit 167. The second filtration unit 167 captures solids contained in the water. The water that has passed through the second filtration section 167 flows into the disinfection tank 170 through an opening 163 formed in the seventh partition wall 207 between the water treatment tanks 160 and 170 .

[0053] The second filtration section 167 includes a plurality of second filtration carriers 168 (also simply referred to as second carriers 168). The second support section 166 is a plate member having a plurality of through holes that are smaller than those of the second carrier 168. The second support section 166 allows water to pass through but prevents water from passing through the second carrier 168. In this embodiment, the second support section 166 is a net made of a material containing resin, similar to the first support section 146. The second support section 166 is fixed to the walls that form the second filtration tank 160 (in this embodiment, partition walls 206, 207).

[0054] The second filtration section 167 is configured to capture finer solid matter than the first filtration section 147. In this embodiment, the second carrier 168 is the same as the first carrier 148. The volume V2 of the second filtration section 167 (i.e., the volume of the plurality of second carriers 168) is larger than the volume V1 of the first filtration section 147 (i.e., the volume of the plurality of first carriers 148). In other words, the total number of the plurality of second carriers 168 forming the second filtration section 167 is larger than the total number of the plurality of first carriers 148 forming the first filtration section 147. With this configuration, the first filtration tank 140 can capture relatively large solid matter, and the second filtration tank 160 can capture relatively small solid matter.

[0055] The second air diffuser 169 has a plurality of holes for discharging air bubbles. The second air diffuser 169 is used to agitate the water and the plurality of second carriers 168 in the second filtration tank 160 (details will be described later). The second filtration tank 160 is not provided with a member (for example, a mesh-like cover member) for preventing the plurality of second carriers 168 from moving upward. In other words, the top of the second filtration tank 160 is open. However, the openings 153, 163 are provided with a member (for example, a mesh) having a plurality of through-holes smaller than the second carriers 168 for allowing water to pass through and preventing the second carriers 168 from passing through (not shown).

[0056] The disinfection tank 170 contains a disinfectant 171, and the water that flows into the disinfection tank 170 is disinfected by the disinfectant 171. The disinfected water flows into the discharge pump tank 180 through an opening 173 formed in the eighth partition wall 208 between the water treatment tanks 170 and 180.

[0057] The discharge pump tank 180 has a discharge pump 181 (for example, an electric pump). The discharge pump 181 transfers the water in the discharge pump tank 180 to the outside of the wastewater treatment device 100.

[0058] The wastewater treatment device 100 has four air lift pumps 310-340. The first air lift pump 310 transfers water from the first filtration tank 140 to the sludge storage tank 190. The first suction port 311 of the first air lift pump 310 is disposed in a position lower than the first filtration section 147 (i.e., the first support section 146) within the first filtration tank 140.

[0059] In this embodiment, the first air lift pump 310 penetrates the fifth partition wall 205 at a first position P1, which is lower than the first support 146, and extends from the first filtration tank 140 to the aerobic filter bed tank 150. The first air lift pump 310 extends from the first position P1 in the aerobic filter bed tank 150 to a position higher than the water level WL5 (the water level WL5 is the water level in the aerobic filter bed tank 150 during normal operation). This is because if the first air lift pump 310 were to extend upward through the first support 146 in the first filtration tank 140, it would require a large manufacturing load to make the gap between the first support 146 and the first air lift pump 310 smaller than that of the first carrier 148. However, the first air lift pump 310 may be configured to penetrate the first support 146 without penetrating the fifth partition wall 205.

[0060] The second air lift pump 320 is a pump for transferring water from the second filtration tank 160 to the sludge storage tank 190. The second suction port 321 of the second air lift pump 320 is disposed in a position within the second filtration tank 160 that is lower than the second filtration section 167 (i.e., the second support section 166).

[0061] In this embodiment, the second air lift pump 320 penetrates the sixth partition wall 206 at a second position P2 that is lower than the second support 166 and extends from the second filtration tank 160 to the aerobic filter bed tank 150. The second air lift pump 320 extends from the second position P2 to a position higher than the water level WL5 within the aerobic filter bed tank 150. The reason for this is that if the second air lift pump 320 were to extend upward through the second support 166 within the second filtration tank 160, it would be difficult to manufacture the gap between the second support 166 and the second air lift pump 320 so that it is smaller than the gap between the second support 166 and the second air lift pump 320. However, the second air lift pump 320 may be configured to penetrate the second support 166 without penetrating the sixth partition wall 206.

[0062] The air lift pump 330 is a pump for transferring water from the settling tank 130 to the sludge storage tank 190 (also referred to as the settling tank air lift pump 330). The third suction port 331 of the settling tank air lift pump 330 is located in the lower portion 130L of the settling tank 130. The lower portion 130L is determined as follows using the water level of the settling tank 130. The water level WL3 in the figure is the water level in the settling tank 130 during normal operation. The intermediate water level WLM is half of this water level WL3. The lower portion 130L is the portion of the settling tank 130 that is below the intermediate water level WLM.

[0063] The three air lift pumps 310, 320, 330 are all connected to a transfer pipe 390. The transfer pipe 390 transfers water from the air lift pumps 310, 320, 330 to the sludge storage tank 190.

[0064] The sludge storage tank 190 is a water treatment tank for storing solids. The sludge storage tank 190 has an inflow baffle 191 and an advection baffle 192. The baffles 191 and 192 are fixed to the walls that form the sludge storage tank 190 (in this embodiment, the inflow baffle 191 is fixed to the third partition wall 203, and the advection baffle 192 is fixed to the second partition wall 202). Water from the transfer pipe 390 flows into the area surrounded by the inflow baffle 191. The inflow baffle 191 moves the water downward and guides it into the sludge storage tank 190. The advection baffle 192 moves the water in the sludge storage tank 190 upward and guides it to another water treatment tank (in this embodiment, the flow rate equalization tank 120). In this embodiment, the water in the area surrounded by the advection baffle 192 flows into the flow rate adjustment tank 120 through an opening 193 formed in the second partition wall 202. The inflow baffle 191 and the advection baffle 192 suppress agitation of the water in the sludge storage tank 190 and short-circuiting of the water passing through the sludge storage tank 190. In the sludge storage tank 190, solids are settled and separated.

[0065] The air lift pump 340 is a pump for transferring water from the aerobic filter bed tank 150 to the first filtration tank 140. The air lift pump 340 circulates water between the first filtration tank 140 and the aerobic filter bed tank 150 (it is also called the circulating air lift pump 340). The suction port 341 of the circulating air lift pump 340 is located in a lower position than the filter bed 158 in the aerobic filter bed tank 150. The circulating air lift pump 340 transfers water pumped up from the aerobic filter bed tank 150 to a region surrounded by the inflow baffle 141 of the first filtration tank 140.

[0066] FIG. 2 is a schematic diagram of a wastewater treatment system 1000. The wastewater treatment system 1000 includes the wastewater treatment device 100, a blower 700, and a control device 600. The blower 700 is a device that discharges air. The blower 700 may include various types of pumps, such as a diaphragm pump or a rotary pump. In addition to the components described in FIG. 1, the wastewater treatment device 100 includes four valves 510-540 and pipes 511-513, 518, 519, 521-523, 528, 529, 535, 536, and 590.

[0067] The pipe 590 is a pipe to be connected to the blower 700 (also referred to as the blower pipe 590). The blower 700 is connected to the blower pipe 590 via an outer pipe 710 provided outside the wastewater treatment device 100. The blower 700 supplies air to the blower pipe 590.

[0068] Pipes 511, 512, and 513 are connected to the air lift pumps 310, 320, and 330, respectively (also referred to as secondary pump air supply pipes 511, 512, and 513). The secondary pump air supply pipes 511, 512, and 513 are connected to a pipe 518 (also referred to as a main pump air supply pipe 518). The main pump air supply pipe 518 and a blower pipe 590 are connected by a first connecting pipe 519. A first valve 510 (also referred to as a transfer valve 510) is provided on the flow path of the first connecting pipe 519.

[0069] Pipes 521, 522, and 523 are connected to first air diffuser 149, second air diffuser 169, and settling tank air diffuser 139, respectively (also referred to as auxiliary air diffusion air supply pipes 521, 522, and 523). Auxiliary air diffusion air supply pipes 521, 522, and 523 are connected to pipe 528 (also referred to as main air diffusion air supply pipe 528). Main air diffusion air supply pipe 528 and blower pipe 590 are connected by second connecting pipe 529. A second valve 520 (also referred to as agitation valve 520) is provided on the flow path of second connecting pipe 529.

[0070] A pipe 536 (also referred to as aerobic diffusion air supply pipe 536) is connected to the aerobic diffusion device 159. The aerobic diffusion air supply pipe 536 is connected to a blower pipe 590. A valve 530 (also referred to as aerobic valve 530) is provided on the flow path of the aerobic diffusion air supply pipe 536.

[0071] A pipe 535 (also referred to as an aerobic pump air supply pipe 535) is connected to the circulation air lift pump 340. The aerobic pump air supply pipe 535 is connected to a portion of the aerobic air diffusion air supply pipe 536 between the aerobic air diffuser 159 and the aerobic valve 530. A valve 540 (also referred to as a circulation valve 540) is provided on the flow path of the aerobic pump air supply pipe 535. The circulation valve 540 is a manual valve. A user (for example, an administrator of the wastewater treatment system 1000) can adjust the amount of water transferred per unit time by the circulation air lift pump 340 by adjusting the opening of the circulation valve 540.

[0072] Each of the valves 510, 520, and 530 has an electrically controllable actuator (e.g., a solenoid), and the state of the valve is controlled by the actuator. The valves 510, 520, and 530 are controlled by a control device 600. In this embodiment, the state of each of the valves 510, 520, and 530 is controlled to either a closed state or an open state.

[0073] The control device 600 is a device that electrically controls various devices, such as a PLC (Programmable Logic Controller), and includes a processor 610, a volatile storage device 620, a non-volatile storage device 630, an output device 640, an input device 650, and an interface 690.

[0074] The processor 610 is a device configured to process data, such as a CPU. The volatile storage device 620 is, for example, a DRAM, and the nonvolatile storage device 630 is, for example, a flash memory. The nonvolatile storage device 630 stores a control program 631. The output device 640 is a device configured to output information, such as a lamp, a liquid crystal display, or an organic EL display. The input device 650 is a device configured to receive user operations, such as a button, a lever, or a touch panel. The interface 690 is an interface for connecting other devices. The interface 690 has, for example, multiple input terminals and multiple output terminals. In this embodiment, the actuators of the valves 510-530 are connected to the output terminals associated with the valves.

[0075] In this embodiment, the control device 600 controls the states of the valves 510-530. The blower 700 is assumed to be continuously operating. Alternatively, the control device 600 may operate the blower 700 intermittently.

[0076] A2. Control processing: Fig. 3 is a flowchart showing an example of the control process. Fig. 4 is a timing chart showing changes in the state of the water treatment tanks 130-160 (specifically, the states of transfer, stirring, aeration, and circulation). The hatched periods indicate periods during operation. The processor 610 of the control device 600 executes the process of Fig. 3 in accordance with the control program 631.

[0077] In S100, the processor 610 executes normal operation. Normal operation is an operating mode in which each of the water treatment tanks 110-190 continuously performs water treatment. In this embodiment, the processor 610 maintains the transfer valve 510 in a closed state, the agitation valve 520 in a closed state, and the aerobic valve 530 in an open state.

[0078] Figures 5(A)-5(C), 6(A), and 6(B) are schematic diagrams showing the respective states of the water treatment tanks 130-160. Each figure shows a schematic diagram of the water treatment tanks 130-160 similar to that shown in Figure 1. Water levels WL3-WL6 indicate the respective water levels of the water treatment tanks 130-160.

[0079] FIG. 5(A) shows the normal operating state. During normal operation, the states of the tanks 130-160 are as follows: Because the transfer valve 510 (FIG. 2) is closed, the air lift pumps 310-330 are stopped. Because the agitation valve 520 is closed, the aeration devices 139, 149, and 169 are stopped. In the impurity removal tank 130, solids are separated from the water. Floating solids 431 (also called scum) may accumulate near the water surface in the impurity removal tank 130. Descending solids 432 may accumulate at the bottom of the impurity removal tank 130. The water treated in the settling tank 130 flows into the first filtration tank 140.

[0080] In the first filtration tank 140, the water passes through the first filtration carrier 148. The first filtration carrier 148 captures solids 441. The water treated in the first filtration tank 140 flows into the aerobic filter bed tank 150.

[0081] In the aerobic filter bed tank 150, the aerobic valve 530 is open, so the aerobic aeration device 159 discharges air bubbles, and the circulating air lift pump 340 transfers water from the aerobic filter bed tank 150 to the first filtration tank 140. The air bubbles discharged by the aerobic aeration device 159 supply oxygen to the water in the aerobic filter bed tank 150 and cause the water in the aerobic filter bed tank 150 to flow. This causes the aerobic filter bed tank 150 to perform aerobic treatment of the water. In addition, solids in the aerobic filter bed tank 150 are transferred together with the water to the first filtration tank 140 by the circulating air lift pump 340. The water treated in the aerobic filter bed tank 150 flows into the second filtration tank 160.

[0082] In the second filtration tank 160, the water passes through a second filtration carrier 168. The second filtration carrier 168 captures solid matter 461. The water treated in the second filtration tank 160 flows into a disinfection tank 170 (FIG. 1).

[0083] The other water treatment tanks 110, 120, 170-190 (Fig. 1) perform their own water treatments as described in Fig. 1. As described above, in normal operation, each of the water treatment tanks 110-190 continues to perform water treatment.

[0084] In this embodiment, the control device 600 is configured to continue normal operation. The control device 600 is also configured to periodically execute a specific process. Process S900 shown in FIG. 3 illustrates an example of the specific process. In this embodiment, the specific process S900 includes steps S110-S190. A first time T1 in FIG. 4 is the start time of the specific process. In this embodiment, the control device 600 starts the specific process S900 at a predetermined first time T1 (the control device 600 executes the specific process S900 once a day).

[0085] In S110 (FIG. 3), the processor 610 opens the transfer valve 510 and closes the aerobic valve 530. The agitation valve 520 is maintained in a closed state. As a result, the processor 610 executes the first transfer process S120. FIG. 5(B) shows the state in the first transfer process S120. Because the aerobic valve 530 is closed, the aerobic aeration device 159 of the aerobic filter bed tank 150 and the circulating air lift pump 340 are stopped. Because the transfer valve 510 is open, the air lift pumps 310, 320, and 330 transfer water from the water treatment tanks 140, 160, and 130 to the sludge storage tank 190. As a result, the water levels WL3, WL4, and WL6 of the water treatment tanks 130, 140, and 160, respectively, drop.

[0086] The reason for lowering the water levels WL3, WL4, and WL6 is as follows. As described below, after the first transfer process S120, an agitation process S140 is performed to agitate the water in the water treatment tanks 130, 140, and 160. Agitating the water can cause the water in the water treatment tanks 130, 140, and 160 to flow out to another water treatment tank through an opening (e.g., openings 133, 143, 153, and 163 (FIG. 1)). Lowering the water levels WL3, WL4, and WL6 by the first transfer process S120 can reduce the possibility of water outflow. As shown in FIG. 4, the processor 610 continues the first transfer process S120 for a first duration DT1 from a first time T1 to a second time T2. The first duration DT1 is experimentally determined in advance (e.g., 10 seconds or more and 5 minutes or less) so that the water levels WL3, WL4, and WL6 are lowered to a level at which water does not flow out during the agitation process S140. The first duration DT1 is preferably determined so as to prevent water from flowing out from the second filtration tank 160 to the disinfection tank 170 during the stirring process S140.

[0087] As the first duration DT1 elapses from the first time T1, the processor 610 operates the valves (S130 (FIG. 3)). The processor 610 closes the transfer valve 510 and opens the agitation valve 520. The aerobic valve 530 is maintained in a closed state. This causes the processor 610 to execute the agitation process S140. FIG. 5(C) shows the state during the agitation process S140. Because the transfer valve 510 is in a closed state, the air lift pumps 310, 320, and 330 are stopped. Because the agitation valve 520 is in an open state, the aeration devices 139, 149, and 169 agitate the water in the water treatment tanks 130, 140, and 160 by discharging air bubbles. In the impurity removal tank 130, the flowing water agitates the solids 433. The solids 433 include floating solids 431 (FIG. 5(B)) and settled solids 432. In the first filtration tank 140, the flowing water agitates the plurality of first carriers 148 and the captured solids 441. As the plurality of first carriers 148 flow, the solids captured on the first carriers 148 detach from the first carriers 148. In the second filtration tank 160, the flowing water agitates the plurality of second carriers 168 and the captured solids 461. As the plurality of second carriers 168 flow, the solids captured on the second carriers 168 detach from the second carriers 168. The process of removing solids adhering to components (e.g., carriers 148, 168) in the water treatment tank from the components by using a water flow in a direction different from the water flow direction during normal operation is also called backwashing.

[0088] 4, the processor 610 continues the stirring process S140 for a second duration DT2 from a second time T2 to a third time T3. The second duration DT2 is experimentally determined in advance (for example, 10 seconds or more and 5 minutes or less) so that the solids 433, 441, 461 in the water treatment tanks 130, 140, 160 are sufficiently stirred.

[0089] As the second duration DT2 elapses from the second time T2, the processor 610 operates the valves (S150 (FIG. 3)). The processor 610 closes the agitation valve 520 and opens the aerobic valve 530. The transfer valve 510 is maintained in a closed state. This causes the processor 610 to execute the sedimentation process S160. FIG. 6(A) shows the state of the sedimentation process S160. The air lift pumps 310-330 and the aeration devices 139, 149, and 169 are stopped. Therefore, the water remains stationary in the impurity removal tank 130, the first filtration tank 140, and the second filtration tank 160. As a result, the agitated solids 433, 441, and 461 settle to the bottom in these water treatment tanks 130, 140, and 160. The concentrations of solids 433, 441, 461 become high at the bottom of the water treatment tanks 130, 140, 160. In addition, in the first filtration tank 140, the plurality of first carriers 148 are deposited on the first support portion 146. In the second filtration tank 160, the plurality of second carriers 168 are deposited on the second support portion 166. Note that, since the aerobic valve 530 is in the open state, the blower 700 (FIG. 2) can continue to operate appropriately (in this embodiment, aerobic treatment is performed in the aerobic filter bed tank 150, similar to the state in FIG. 5(A)).

[0090] 4, the processor 610 continues the settling process S160 for a third duration DT3 from a third time T3 to a fourth time T4. The third duration DT3 is experimentally determined in advance (e.g., one minute or more and one hour or less) so that the solids 433, 441, 461 in the water treatment tanks 130, 140, 160 can be sufficiently settled.

[0091] As the third duration DT3 elapses from the third time T3, the processor 610 operates the valves (S170 (FIG. 3)). The processor 610 opens the transfer valve 510 and closes the aerobic valve 530. The agitation valve 520 is maintained in a closed state. As a result, the processor 610 executes a second transfer process S180. FIG. 6(B) shows the state in the second transfer process S180. Because the transfer valve 510 is in an open state, the air lift pumps 310-330 transfer the water from the water treatment tanks 140, 160, and 130 to the sludge storage tank 190. As a result, the solids 433, 441, and 461 that have settled to the bottom of the water treatment tanks 130, 140, and 160 are transferred to the sludge storage tank 190.

[0092] 4, the processor 610 continues the second transfer process S180 for a fourth duration DT4 from a fourth time T4 to a fifth time T5. The fourth duration DT4 is experimentally determined in advance so as to transfer a sufficient amount of solids 433, 441, 461 (for example, 30 seconds or more and 5 minutes or less).

[0093] As described in FIG. 1, solids are separated by settling in the sludge storage tank 190. Therefore, the sludge storage tank 190 can appropriately store the solids transferred from the water treatment tanks 130, 140, and 160. The water treated in the sludge storage tank 190 flows into the flow rate adjustment tank 120. The water in the flow rate adjustment tank 120 is transferred little by little to the impurity removal tank 130 through the metering adjustment device 122. In this embodiment, in the processes S120-S180, the rise in the water levels WL3, WL4, and WL6 of the water treatment tanks 130, 140, and 160 due to the water transferred from the flow rate adjustment tank 120 is small enough to prevent the water from flowing out of the openings (e.g., openings 133, 143, 153, and 163 (FIG. 1)) of the water treatment tanks 130, 140, and 160.

[0094] In response to the passage of a fourth duration DT4 from a fourth time T4, the processor 610 operates the valves (S190 (FIG. 3)). The processor 610 closes the transfer valve 510 and opens the aerobic valve 530. The state of the agitation valve 520 is maintained in the closed state. As a result, the processor 610 ends the specific process S900 and starts normal operation (S200).

[0095] As described above, the wastewater treatment apparatus 100 (FIG. 1) of this embodiment has multiple water treatment tanks 110-190, including the first filtration tank 140, the aerobic filter bed tank 150, which is an example of an aerobic treatment tank, located downstream of the first filtration tank 140, and the second filtration tank 160, which is located downstream of the aerobic filter bed tank 150. The aerobic filter bed tank 150 has a filter bed 158, which is an example of a fixed bed. Water from which solids have been separated by the first filtration tank 140 flows into the aerobic filter bed tank 150. That is, the amount of solids flowing into the aerobic filter bed tank 150 is reduced by the first filtration tank 140. Furthermore, because the aerobic filter bed tank 150 has a fixed bed (here, filter bed 158), the possibility of crushing the solids flowing into the aerobic filter bed tank 150 is reduced. If the aerobic filter bed tank 150 had multiple carriers that flowed with the water, the multiple carriers could crush the solids upon contact with them. In this embodiment, the aerobic filter bed tank 150 does not have such carriers, so such crushing of solids is avoided. Furthermore, because the possibility of solids being crushed in the aerobic filter bed tank 150 is reduced, the second filtration tank 160 can easily capture solids contained in the water from the aerobic filter bed tank 150. If solids were crushed in the aerobic filter bed tank 150, the crushed, smaller solids could flow downstream from the second filtration tank 160 without being captured by the second filtration section 167 of the second filtration tank 160. In this embodiment, the possibility of solids flowing out from the second filtration tank 160 is reduced. In this way, the wastewater treatment device 100 can properly separate solids from water.

[0096] The wastewater treatment device 100 (FIG. 1) has a second air lift pump 320 and a circulating air lift pump 340. The second air lift pump 320 is configured to transfer water from the second filtration tank 160 to the sludge storage tank 190. The second filtration tank 160 is located downstream of the aerobic filter bed tank 150. The second filtration tank 160 is an example of a "first target tank that is either an aerobic treatment tank or a water treatment tank located downstream of the aerobic treatment tank." The sludge storage tank 190 is a storage tank for storing solids. The sludge storage tank 190 is an example of a "second target tank that is either a first filtration tank, a water treatment tank located upstream of the first filtration tank, a storage tank for storing solids, or an anaerobic treatment tank." The second air lift pump 320 is an example of a target transfer device configured to transfer water from the first target tank to the second target tank. The circulating air lift pump 340 is configured to transfer water from the aerobic filter bed tank 150 to the first filtration tank 140. The aerobic filter bed tank 150 is an example of the first target tank described above. The first filtration tank 140 is an example of the second target tank described above. The circulating air lift pump 340 is an example of a target transfer device configured to transfer water from the first target tank to the second target tank. Generally, a wastewater treatment device having an aerobic treatment tank discharges treated water from the aerobic treatment tank outside the wastewater treatment device. The target transfer devices 320, 340 can transfer solids along with water from the aerobic filter bed tank 150 or a water treatment tank located downstream of the aerobic filter bed tank 150 to the second target tank. Therefore, the wastewater treatment device 100 can reduce the amount of solids contained in the water in the aerobic filter bed tank 150 or a water treatment tank located downstream of the aerobic filter bed tank 150, and ultimately the amount of solids contained in the water discharged outside the wastewater treatment device 100.

[0097] The multiple water treatment tanks 110-190 of the wastewater treatment device 100 (FIG. 1) include a disinfection tank 170 subsequent to the second filtration tank 160. As such, no other water treatment tank is provided between the second filtration tank 160 and the disinfection tank 170. For example, no treated water tank is provided to temporarily store water from the second filtration tank 160. This allows the wastewater treatment device 100 to be made smaller.

[0098] The first filtration tank 140 (FIG. 1) has a first filtration section 147 including a plurality of first supports 148. The second filtration tank 160 has a second filtration section 167 including a plurality of second supports 168. The second support 168 of the second filtration section 167 is the same as the first support 148 of the first filtration section 147. If the supports were different between the first filtration section 147 and the second filtration section 167, the wrong support could be used to manufacture the first filtration section 147 or the second filtration section 167. For example, the second support 168 could be mistakenly placed in the first filtration tank 140. In this embodiment, the same support forms the first filtration section 147 and the second filtration section 167, so such a problem can be avoided.

[0099] The volume V2 of the plurality of second carriers 168 of the second filtration section 167 (FIG. 1) is larger than the volume V1 of the plurality of first carriers 148 of the first filtration section 147. With this configuration, the first filtration tank 140 can capture relatively large solids, and the second filtration tank 160 can capture relatively small solids. Therefore, the wastewater treatment device 100 can properly separate solids.

[0100] The volume of the multiple carriers can be measured as follows: A container forming a storage space with a rectangular parallelepiped shape is prepared. The container is placed so that the rectangular bottom surface forming the bottom of the storage space is horizontal. The multiple carriers are placed into the container. Inside the container, the multiple carriers may form peaks with higher heights from the bottom surface and valleys with lower heights. The variation in height from the bottom surface is reduced by moving the multiple carriers from the peaks to the valleys. The variation in height may also be reduced by vibrating the container. As a result, the multiple carriers form an approximately horizontal upper surface. A flat lid having a rectangular shape roughly the same as the rectangular bottom surface is placed on the multiple carriers inside the container. The flat lid is placed on the multiple carriers while maintaining its parallelism with the bottom surface. In this state, the volume of the rectangular parallelepiped enclosed by the container and the flat lid can be used as the volume of the multiple carriers.

[0101] As described with reference to FIG. 1 , the top of the first filtration tank 140 is open, and the top of the second filtration tank 160 is open. Therefore, the complexity of manufacturing the first filtration tank 140 and the second filtration tank 160 can be reduced. For example, the process of fixing cover members to the first filtration tank 140 and the second filtration tank 160 can be omitted. Furthermore, the specific gravity of the first carrier 148 of the first filtration unit 147 is greater than 1, and the specific gravity of the second carrier 168 of the second filtration unit 167 is greater than 1. Therefore, the possibility of the first carrier 148 leaking out from the top of the first filtration tank 140 and the possibility of the second carrier 168 leaking out from the top of the second filtration tank 160 are reduced.

[0102] As shown in FIG. 1, the first air lift pump 310 has a first suction port 311 disposed in the first filtration tank 140. The second air lift pump 320 has a second suction port 321 disposed in the second filtration tank 160. As shown in FIG. 2, a first auxiliary pump air supply pipe 511 is connected to the first air lift pump 310, and a second auxiliary pump air supply pipe 512 is connected to the second air lift pump 320. These auxiliary pump air supply pipes 511 and 512 are connected to a main pump air supply pipe 518. These pump air supply pipes 511, 512, and 518 together are an example of a pump connecting pipe (referred to as a pump connecting pipe 517) that connects the first air lift pump 310 and the second air lift pump 320. A first connecting pipe 519 connects a blower pipe 590 to the pump connecting pipe 517 (specifically, the main pump air supply pipe 518). A first valve 510 is provided on the flow path of the first connecting pipe 519. No valve is provided on the flow path of the pump connecting pipe 517 (511, 512, 518) from the first air lift pump 310 to the second air lift pump 320. Therefore, the first air lift pump 310 and the second air lift pump 320 cannot operate independently. The air lift pumps 310 and 320 simultaneously transfer water from the first filtration tank 140 and the second filtration tank 160. In this way, the transfer of water from the first filtration tank 140 and the transfer of water from the second filtration tank 160 proceed simultaneously. The air lift pumps 310, 320, pipes 517 (511, 512, 518), 519, and first valve 510 together constitute an example of a first transfer device (also referred to as a first transfer device 910) configured to transfer water from both the first filtration tank 140 and the second filtration tank 160. Here, the destination of the water from the first filtration tank 140 is a water treatment tank (in this embodiment, the sludge storage tank 190) different from the first filtration tank 140. The destination of the water from the second filtration tank 160 is a water treatment tank (in this embodiment, the sludge storage tank 190) different from the second filtration tank 160.

[0103] As shown in FIG. 1, the first air diffuser 149 is disposed in the first filtration tank 140. The second air diffuser 169 is disposed in the second filtration tank 160. As shown in FIG. 2, a first auxiliary air diffusion air supply pipe 521 is connected to the first air diffuser 149, and a second auxiliary air diffusion air supply pipe 522 is connected to the second air diffuser 169. These auxiliary air diffusion air supply pipes 521, 522 are connected to a main air diffusion air supply pipe 528. The entire air diffusion air supply pipes 521, 522, 528 are an example of an air diffusion connecting pipe (referred to as an air diffusion connecting pipe 527) that connects the first air diffuser 149 and the second air diffuser 169. The second connecting pipe 529 connects a blower pipe 590 to the air diffusion connecting pipe 527 (specifically, the main air diffusion air supply pipe 528). A second valve 520 is provided on the flow path of the second connecting pipe 529. No valve is provided on the flow path of the air diffusion connecting pipe 527 (521, 522, 528) from the first air diffuser 149 to the second filtration tank 160. Therefore, the first air diffuser 149 and the second air diffuser 169 cannot operate independently. The air diffusers 149 and 169 agitate the water in the first filtration tank 140 and the water in the second filtration tank 160 at the same time. In this way, agitation of the water in the first filtration tank 140 and the water in the second filtration tank 160 proceeds simultaneously. The entire combination of the aeration devices 149, 169, the pipes 527 (521, 522, 528), 529, and the second valve 520 is an example of an agitation device (also referred to as agitation device 920) configured to agitate the water in both the first filtration tank 140 and the second filtration tank 160.

[0104] As described above, the wastewater treatment device 100 includes the first transfer device 910 and the agitation device 920. Therefore, the wastewater treatment device 100 can reduce the amount of solids in the first filtration tank 140 and the second filtration tank 160 through agitation by the agitation device 920 and transfer by the first transfer device 910. This allows the filtration tanks 140, 160 to continue separating solids without the need for an operator to clean the filtration tanks 140, 160 (e.g., by removing the solids outside the wastewater treatment device 100). Furthermore, by operating the first valve 510 and the second valve 520, the transfer of water from the first filtration tank 140 and the second filtration tank 160 and the agitation of the water in the first filtration tank 140 and the water in the second filtration tank 160 can be easily controlled. Furthermore, the complexity of the configuration of the wastewater treatment device 100 can be reduced. For example, in order to independently control the first air lift pump 310 and the second air lift pump 320, a valve for the first air lift pump 310 and a valve for the second air lift pump 320 are added. In this embodiment, such additional components can be omitted.

[0105] The multiple water treatment tanks 110-190 of the wastewater treatment device 100 (FIG. 1) include a settling tank 130 and a sludge storage tank 190. The settling tank 130 is configured to settle solids without filtering them (in this embodiment, the settling tank 130 has an inlet baffle 131 and an advection baffle 132). The sludge storage tank 190 is configured to store solids (in this embodiment, the sludge storage tank 190 has an inlet baffle 191 and an advection baffle 192).

[0106] A settling tank aeration device 139 is disposed within the settling tank 130 (FIG. 1) to agitate the water within the settling tank 130. As shown in FIG. 2, a third auxiliary aeration supply pipe 523 is connected to the settling tank aeration device 139, which is connected to a main aeration supply pipe 528. The main aeration supply pipe 528 is connected to a second connecting pipe 529, and a second valve 520 is provided in the flow path of the second connecting pipe 529. The agitation of the water by the settling tank aeration device 139 can be controlled by the second valve 520. The settling tank aeration device 139, the pipes 523, 528, and 529, and the second valve 520 together are an example of a settling tank agitator configured to agitate the water within the settling tank 130 (also referred to as a settling tank agitator 930, or simply as an agitator 930).

[0107] The settling tank air lift pump 330 (FIG. 1) has a third suction port 331 disposed within the settling tank 130. As shown in FIG. 2, a third auxiliary pump air supply pipe 513 is connected to the settling tank air lift pump 330, which is connected to a main pump air supply pipe 518. The main pump air supply pipe 518 is connected to a first connecting pipe 519, and a first valve 510 is provided in the flow path of the first connecting pipe 519. The transfer of water by the settling tank air lift pump 330 can be controlled by the first valve 510. The settling tank air lift pump 330, the pipes 513, 518, 519, and the first valve 510 collectively constitute an example of a second transfer device (also referred to as a second transfer device 940, or simply as a transfer device 940) configured to transfer water from the settling tank 130 to the sludge storage tank 190.

[0108] The wastewater treatment system 1000 (FIG. 2) includes a control device 600 configured to control the settling tank agitation device 930 and the second transfer device 940. As shown in FIG. 3, the control device 600 is configured to execute a specific process S900. The specific process S900 includes an agitation process S140 and a second transfer process S180. The agitation process S140 includes an agitation process in which the settling tank agitation device 930 agitates the water in the settling tank 130. The second transfer process S180 includes a transfer process in which, after the agitation process S140, the second transfer device 940 transfers water containing solids from the settling tank 130 to the sludge storage tank 190. According to this configuration, the settled solids 432 and the floating solids 431 in the settling tank 130 (FIG. 5(A)) are agitated by the agitation process S140 (FIG. 5(C)). Then, the second transfer process S180 (FIG. 6(B)) is performed after the agitation process S140. Therefore, the settling tank air lift pump 330 of the second transfer device 940 can appropriately transfer the solids 433 including the settled solids 432 and the floated solids 431. Furthermore, the settling tank 130 can continue to separate the solids even without the need for an operator to clean the settling tank 130 (for example, by pulling the solids out of the wastewater treatment device 100).

[0109] In this embodiment, the multiple water treatment tanks 110-190 include a first filtration tank 140. The settling tank 130 is disposed upstream of the first filtration tank 140. The water from which solids have been separated by the settling tank 130 flows into the first filtration tank 140. This reduces the load on the first filtration tank 140, allowing the first filtration tank 140 to perform filtration appropriately. For example, the possibility of the first filtration section 147 being clogged by solids is reduced.

[0110] In this embodiment, the control device 600 (FIG. 2) is configured to control the first transfer device 910 and the agitator 920 in addition to the settling tank agitator 930 and the second transfer device 940. The agitation process S140 (FIGS. 3 and 5(C)) includes a process in which the agitator 920 agitates the water in the first filtration tank 140 and the water in the second filtration tank 160 at the same time. The second transfer process S180 (FIG. 6(B)) includes a process in which the first transfer device 910 transfers water from the first filtration tank 140 and the water from the second filtration tank 160 at the same time. Therefore, the air lift pumps 310 and 320 of the first transfer device 910 can appropriately transfer the solids 441 in the first filtration tank 140 and the solids 461 in the second filtration tank 160. This allows the filtration tanks 140, 160 to continue separating solid matter even without the need for an operator to clean the filtration tanks 140, 160 (for example, by removing the solid matter from the wastewater treatment device 100).

[0111] The settling tank air lift pump 330 (FIG. 1) of the second transfer device 940 has a third suction port 331 located in the lower portion 130L of the settling tank 130. The specific process S900 (FIG. 3) includes a settling process S160, which is performed after the agitation process S140 and before the second transfer process S180. The settling process S160 (FIG. 6(A)) includes a settling process in which solids are allowed to settle in the settling tank 130 by stopping both the agitation by the settling tank agitator 930 and the transfer by the second transfer device 940. With this configuration, the settling tank air lift pump 330 of the second transfer device 940 can transfer water with a high concentration of solids 433 in the second transfer process S180 (FIG. 6(B)). Therefore, the total amount of water transferred by the settling tank air lift pump 330 in one cycle of the second transfer process S180 can be reduced. The water transferred to the sludge storage tank 190 by the settling tank air lift pump 330 can generate a water current within the sludge storage tank 190. The strong water current can lift settled solids into the water. The lifted solids can flow out of the sludge storage tank 190 along with the water. When the total amount of water transferred is small, the water current within the sludge storage tank 190 generated by the transferred water is weaker than when the total amount of water transferred is large. Therefore, the amount of solids flowing out of the sludge storage tank 190 is reduced.

[0112] The first air lift pump 310 (FIG. 1) of the first transfer device 910 (FIG. 2) has a first suction port 311 located in a portion of the first filtration tank 140 that is lower than the first filtration section 147. The second air lift pump 320 has a second suction port 321 located in a portion of the second filtration tank 160 that is lower than the second filtration section 167. The settling process S160 (FIGS. 3 and 6(A)) includes a settling process in which solids are allowed to settle in the filtration tanks 140 and 160 by stopping both the agitation by the agitator 920 and the transfer by the first transfer device 910. With this configuration, the air lift pumps 310 and 320 of the first transfer device 910 can transfer water having a high concentration of solids 441 and 461 in the second transfer process S180 (FIG. 6(B)). Therefore, the total amount of water transferred by the air lift pumps 310 and 320 in one second transfer process S180 can be reduced. When the total amount of transferred water is small, the water flow generated by the transferred water in the sludge storage tank 190 is weaker than when the total amount of transferred water is large. Therefore, the amount of solids that flow out of the sludge storage tank 190 is reduced.

[0113] 4, in this embodiment, the control device 600 is configured to execute the specific process S900 once a day. Therefore, compared to when the specific process S900 is executed less frequently (for example, once every two days), the amount of solid matter remaining in the settling tank 130 can be reduced. Furthermore, in this embodiment, the amount of solid matter remaining in the filtration tanks 140 and 160 can be reduced.

[0114] As shown in Fig. 3, the specific process S900 includes a first transfer process S120 that is executed before the agitation process S140. The first transfer process S120 includes a process in which the settling tank air lift pump 330 of the second transfer device 940 (Fig. 2) transfers water from the settling tank 130 to the sludge storage tank 190. According to this configuration, the agitation process (agitation process S140) of the settling tank 130 is performed in a state in which the water level WL3 of the settling tank 130 (Fig. 5(C)) has been lowered by the transfer of water, thereby reducing the possibility of solids overflowing from the settling tank 130 during the agitation process.

[0115] The first transfer process S120 includes a process in which the air lift pumps 310, 320 of the first transfer device 910 (FIG. 2) simultaneously transfer water from the first filtration tank 140 and transfer water from the second filtration tank 160. According to this configuration, the agitation process (agitation process S140) of the filtration tanks 140, 160 is performed in a state in which WL4, WL6 of the filtration tanks 140, 160 (FIG. 5(C)) have been lowered by the transfer of water, thereby reducing the possibility of solid matter overflowing from the filtration tanks 140, 160 during the agitation process.

[0116] As shown in FIG. 1 , the multiple water treatment tanks 110-190 of the wastewater treatment device 100 include a flow rate adjustment tank 120. The wastewater treatment device 100 has a second partition wall 202 that forms an opening 193. The opening 193 is an example of a flow path connecting the flow rate adjustment tank 120 and the sludge storage tank 190. Water transferred to the sludge storage tank 190 flows into the flow rate adjustment tank 120 through the opening 193 after solids are separated. This reduces the possibility of water overflowing from the sludge storage tank 190 to the outside of the wastewater treatment device 100. The flow rate adjustment tank 120 is located upstream of the settling tank 130. The flow rate adjustment tank 120 is an example of a "target tank that is either a settling tank or a water treatment tank located upstream of the settling tank." The opening 193 is an example of a "flow path connecting a storage tank and a target tank."

[0117] As shown in Figure 1, the multiple water treatment tanks 110-190 of the wastewater treatment device 100 include an aerobic filter bed tank 150 located downstream of the settling tank 130. Water from which solids have been separated by the settling tank 130 flows into the aerobic filter bed tank 150. This reduces the load on the aerobic filter bed tank 150, allowing the aerobic filter bed tank 150 to properly perform aerobic treatment. In this way, the wastewater treatment device 100 can properly treat wastewater.

[0118] B. Second Example: Fig. 7 is a flowchart showing an example of a schedule determination process. Fig. 8 is a flowchart showing an example of a schedule execution process. The configuration of the wastewater treatment system of this embodiment is the same as the configuration of the wastewater treatment system 1000 of the first embodiment, except that the control program 631 (Fig. 2) is configured to execute these processes. In this embodiment, the control device 600 allows the user to determine a schedule including the number of times N that the specific process S900 (Fig. 3) is executed per day and the start time of each of the N specific processes S900. Then, the control device 600 executes the specific process S900 according to the schedule determined by the user.

[0119] The user inputs instructions for determining a schedule by operating input device 650 (FIG. 2). In response to the instructions, processor 610 starts the processing of FIG.

[0120] In S310, processor 610 accepts input of the number of times N that a task has been performed in a day. The user inputs the number of times N that a task has been performed by operating input device 650. The number of times N that a task has been performed may be any integer equal to or greater than 1. In S320, processor 610 stores data indicating the input number of times N that a task has been performed in volatile storage device 620.

[0121] In S330, the processor 610 initializes the number i to 1. In S340, the processor 610 accepts input of the start time of the i-th specific process S900. The user inputs the start time of the i-th specific process S900 by operating the input device 650. It is preferable that the specific process S900 be performed during a time period when there is little wastewater inflow into the wastewater treatment device 100 (for example, the time period from 00:00 (midnight) in the middle of the night to 05:00 (5 o'clock) in the morning). In S350, the processor 610 stores data indicating the input start time in the volatile storage device 620.

[0122] In S360, the processor 610 determines whether all N start times have been determined. In this embodiment, when i = N, the determination result is Yes. If the determination result is No (i.e., i < N), the processor 610 adds 1 to the number i in S370 and proceeds to S340. Then, it executes the process for the start time of the new number i.

[0123] The start time of the i-th time is set to a time after the time obtained by adding the processing time, which is the time required for one specific process S900, to the start time of the (i - 1)-th time. For example, if the start time of the (i - 1)-th time is 00:00 and the processing time is 15 minutes, the start time of the i-th time is set to a time after 00:15. By increasing the difference in start times between the (i - 1)-th and i-th times, the precipitation of solids in the water treatment tanks 130, 140, and 160 can be promoted during the time between the specific processes S900 of the (i - 1)-th and i-th times. For example, when the processing time is about 15 minutes, the start time of the i-th time may be 1 hour after the start time of the (i - 1)-th time.

[0124] When i = N in S360 (S360: Yes), the processor 610 ends the process of FIG. 7.

[0125] The processor 610 executes each of the N specific processes S900 by repeatedly executing the schedule execution process of FIG. 8. In S410, the processor 610 acquires the current time. In this embodiment, the control device 600 has a timer (not shown). The processor 610 acquires the current time from the timer.

[0126] In S420, processor 610 determines whether the current time is the same as any of the N start times. If the current time is different from all of the N start times (S420: No), processor 610 proceeds to S410. If the current time is the same as any of the start times (S420: Yes), in S430, processor 610 executes identification process S900. Processor 610 executes identification process S900 according to the same procedures as those described in FIGS. 3 and 4. Note that in this embodiment, first time T1 in FIG. 4 indicates the start time determined to be the same as the current time in S420.

[0127] As described above, in this embodiment, the control device 600 is configured to execute the specific process S900 N times per day (N is an integer equal to or greater than 1). Therefore, compared to when the specific process S900 is executed less frequently (for example, once every two days), the amount of solid matter remaining in the settling tank 130 can be reduced. Furthermore, in this embodiment, the amount of solid matter remaining in the filtration tanks 140 and 160 can be reduced.

[0128] The control device 600 is also configured to allow the user to change the number of times N per day that the specific treatment S900 is performed. The user can adjust the number of times N per day that the specific treatment S900 is performed according to the status of the wastewater treatment device 100. For example, if the concentration of solids contained in the water treated by the wastewater treatment device 100 is sufficiently low, the user may reduce the number of times N that the specific treatment S900 is performed. If the concentration of solids is high, the user may increase the number of times N that the specific treatment S900 is performed. As the concentration of solids, for example, the concentration of suspended solids (also called SS (suspended solids)) may be used (a common unit is mg / L).

[0129] C. Third Example: Figure 9 is a schematic diagram of another embodiment of a wastewater treatment system. The difference from the wastewater treatment system 1000 of Figure 2 is that three air lift pumps 310-330 and three air diffusers 139, 149, 169 are each provided with a valve. A control program 631b of the control device 600 is configured to control these valves (details will be described later). The configuration of other parts of the wastewater treatment system 1000b is the same as the configuration of the corresponding parts of the wastewater treatment system 1000 of the first embodiment (illustrations and descriptions of the same parts will be omitted).

[0130] The wastewater treatment system 1000b of this embodiment includes a wastewater treatment device 100b, a blower 700, and a control device 600. The wastewater treatment device 100b includes eight valves 510a-510c, 520a-520c, 530, and 540, and pipes 511-513, 521-523, 535, 536, and 590, in addition to the components described in FIG.

[0131] The aerobic pump air supply pipe 535, the aerobic air diffusion air supply pipe 536, and the blower pipe 590 are the same as the pipes 535, 536, and 590, respectively, in the embodiment of FIG.

[0132] Sub pump air supply pipes 511, 512, and 513 are connected to the air lift pumps 310, 320, and 330, respectively. Unlike the embodiment in Fig. 2, the main pump air supply pipe 518 is omitted. The sub pump air supply pipes 511, 512, and 513 are each connected to a blower pipe 590. Transfer valves 510a, 510b, and 510c are provided on the flow paths of the sub pump air supply pipes 511, 512, and 513, respectively.

[0133] Auxiliary air diffusion air supply pipes 521, 522, 523 are connected to the air diffusers 149, 169, 139, respectively. Unlike the embodiment in Fig. 2, the main air diffusion air supply pipe 528 is omitted. Auxiliary air diffusion air supply pipes 521, 522, 523 are each connected to a blower pipe 590. Agitation valves 520a, 520b, 520c are provided on the flow paths of auxiliary air diffusion air supply pipes 521, 522, 523, respectively.

[0134] Transfer valves 510a-510c, agitation valves 520a-520c, and aerobic valve 530 each have an electrically controllable actuator (e.g., a solenoid). The actuators of these valves 510a-510c, 520a-520c, and 530 are connected to an interface 690 of controller 600. Valves 510a-510c, 520a-520c, and 530 are controlled by controller 600. In this embodiment, the state of each of valves 510a-510c, 520a-520c, and 530 is controlled to either a closed state or an open state.

[0135] 10 is a timing chart showing changes in the state of the water treatment tanks 130, 140, 160 (specifically, the execution state of the specific process S900). The hatched periods indicate the periods during which the specific process S900 is being executed. Unlike the embodiment of FIG. 4, the processor 610 of the control device 600 executes the specific process S900 of the settling tank 130, the specific process S900 of the first filtration tank 140, and the specific process S900 of the second filtration tank 160 at different times.

[0136] The processor 610 starts a specific process S900 for the settling tank 130 at a predetermined first start time T11. The specific process S900 for the settling tank 130 is obtained by replacing the transfer valve 510 with a third transfer valve 510c and the agitation valve 520 with a third agitation valve 520c in the specific process S900 of FIG. 3. The transfer valves 510a and 510b and the agitation valves 520a and 520b for the filtration tanks 140 and 160 are maintained in a closed state. By this specific process S900, solids in the settling tank 130 are transferred to the sludge storage tank 190, similar to the embodiments of FIGS. 5(A)-5(C), 6(A), and 6(C). The specific process S900 for the settling tank 130 ends at a first end time T12 (FIG. 10).

[0137] At a second start time T13, which is a predetermined first waiting time DT11 after the first end time T12, the processor 610 starts a specific process S900 for the first filtration tank 140. The specific process S900 for the first filtration tank 140 is obtained by replacing the transfer valve 510 with a first transfer valve 510a and the agitation valve 520 with a first agitation valve 520a in the process of FIG. 3. The transfer valves 510b and 510c and the agitation valves 520b and 520c for the second filtration tank 160 and the settling tank 130 are maintained in a closed state. By this specific process S900, the solids in the first filtration tank 140 are transferred to the sludge storage tank 190, similar to the embodiments of FIGS. 5(A)-5(C), 6(A), and 6(C). The specific process S900 for the first filtration tank 140 ends at a second end time T14 (FIG. 10).

[0138] At a third start time T15, which is a predetermined second waiting time DT12 after the second end time T14, the processor 610 starts a specific process S900 for the second filtration tank 160. The specific process S900 for the second filtration tank 160 is obtained by replacing the transfer valve 510 with a second transfer valve 510b and the agitation valve 520 with a second agitation valve 520b in the process of FIG. 3. The transfer valves 510a and 510c and the agitation valves 520a and 520c for the first filtration tank 140 and the settling tank 130 are maintained in a closed state. By this specific process S900, the solids in the second filtration tank 160 are transferred to the sludge storage tank 190, similar to the embodiments of FIGS. 5(A)-5(C), 6(A), and 6(C). The specific process S900 for the second filtration tank 160 ends at the third end time T16 (FIG. 10).

[0139] After the third end time T16, the processor 610 executes normal operation until the start time of the specific process S900 for the next settling tank 130.

[0140] As described above, the wastewater treatment device 100b (FIG. 9) of this embodiment includes air lift pumps 310 and 320, aeration devices 149 and 169, a blower pipe 590, auxiliary pump air supply pipes 511 and 512, transfer valves 510a and 510b, auxiliary air diffusion air supply pipes 521 and 522, and agitation valves 520a and 520b. The first air lift pump 310 is configured to transfer water from the first filtration tank 140 to a water treatment tank other than the first filtration tank 140 (in this embodiment, the sludge storage tank 190). The second air lift pump 320 is configured to transfer water from the second filtration tank 160 to a water treatment tank other than the second filtration tank 160 (in this embodiment, the sludge storage tank 190). The first air diffuser 149 is configured to agitate the water in the first filtration tank 140. The second air diffuser 169 is configured to agitate the water in the second filtration tank 160. The blower pipe 590 is a pipe to be connected to the blower 700. The first auxiliary pump air supply pipe 511 is an example of a first connecting pipe connecting the blower pipe 590 and the first air lift pump 310. The first transfer valve 510a is an example of a first valve provided on the flow path of the first connecting pipe (in this embodiment, the first auxiliary pump air supply pipe 511). The second auxiliary pump air supply pipe 512 is an example of a second connecting pipe connecting the blower pipe 590 and the second air lift pump 320. The second transfer valve 510b is an example of a second valve provided on the flow path of the second connecting pipe (in this embodiment, the second auxiliary pump air supply pipe 512). The first auxiliary air diffuser air supply pipe 521 is an example of a third connecting pipe connecting the blower pipe 590 and the first air diffuser 149. The first agitation valve 520a is an example of a third valve provided on the flow path of the third connecting pipe (in this embodiment, the first auxiliary air diffusion air supply pipe 521). The second auxiliary air diffusion air supply pipe 522 is an example of a fourth connecting pipe that connects the blower pipe 590 and the second air diffuser 169. The second agitation valve 520b is an example of a fourth valve provided on the flow path of the fourth connecting pipe (in this embodiment, the second auxiliary air diffusion air supply pipe 522). With this configuration, the four valves 510a, 510b, 520a, and 520b can easily and independently control the transfer of water from the first filtration tank 140, the transfer of water from the second filtration tank 160, the agitation of the water in the first filtration tank 140, and the agitation of the water in the second filtration tank 160.

[0141] In this embodiment, the wastewater treatment device 100b further includes a settling tank air lift pump 330, a settling tank aeration device 139, a third auxiliary pump air supply pipe 513, a third transfer valve 510c, a third auxiliary air supply pipe 523, and a third agitation valve 520c. The settling tank air lift pump 330 is configured to transfer water from the settling tank 130 to a water treatment tank other than the settling tank 130 (in this embodiment, the sludge storage tank 190). The settling tank aeration device 139 is configured to agitate the water in the settling tank 130. The third auxiliary pump air supply pipe 513 connects a blower pipe 590 to the settling tank air lift pump 330. The third transfer valve 510c is provided in the flow path of the third auxiliary pump air supply pipe 513. The third auxiliary air supply pipe 523 connects the blower pipe 590 to the settling tank aeration device 139. Third agitation valve 520c is provided on the flow path of third auxiliary aeration supply pipe 523. Therefore, the transfer of water from each of water treatment tanks 130, 140, 160 and the agitation of water in each of water treatment tanks 130, 140, 160 can be easily and independently controlled by six valves 510a, 510b, 510c, 520a, 520b, 520c.

[0142] In this embodiment, the settling tank aeration device 139, the pipe 523, and the third agitation valve 520c together constitute an example of a settling tank agitation device configured to agitate the water in the settling tank 130 (also referred to as a settling tank agitation device 930b). The settling tank air lift pump 330, the pipe 513, and the third transfer valve 510c together constitute an example of a second transfer device configured to transfer water from the settling tank 130 to the sludge storage tank 190 (also referred to as a second transfer device 940b). The control device 600 is configured to control the settling tank agitation device 930b and the second transfer device 940b. The control device 600 executes the specific process S900 (FIG. 3) as described above. Therefore, the settling tank air lift pump 330 of the second transfer device 940b can appropriately transfer solids, including settled solids and floated solids.

[0143] 10, the control device 600 executes the specific treatment S900 for each of the water treatment tanks 130, 140, and 160 at different times. The treatment time (T11-T12) for the impurity removal tank 130, the treatment time (T13-T14) for the first filtration tank 140, and the treatment time (T15-T16) for the second filtration tank 160 do not overlap with one another. Therefore, the amount of water transferred per unit time to the sludge storage tank 190 is reduced compared to when the specific treatment S900 for two or more water treatment tanks is executed at the same time. As a result, the water flow in the sludge storage tank 190 generated by the transferred water is weakened, and the amount of solids outflowing from the sludge storage tank 190 is reduced.

[0144] D. Fourth Example: FIG. 11 is a schematic diagram showing another embodiment of a wastewater treatment device. The figure shows a wastewater treatment device 100d viewed from the side. The wastewater treatment device 100d of this embodiment has a body 200d. The body 200d houses a settling tank 110d, a storage tank 120d, an anaerobic treatment tank 130d, an aerobic treatment tank 140d, a treated water tank 150d, and a disinfection tank 160d. In this embodiment, the water treatment tanks 110d-160d are arranged in the body 200d in the following order: water treatment tanks 120d, 110d, 130d, 140d, 150d, 160d. The body 200d has multiple walls (including partition walls 201d-205d) that form these water treatment tanks 110d-160d.

[0145] Wastewater flowing into the wastewater treatment device 100d is guided to a settling tank 110d via a transfer pipe 115d. The settling tank 110d is a water treatment tank in which solids are separated by settling. The settling tank 110d has an inflow baffle 111d, an advection baffle 112d, and an aeration device 119d. The settling tank 110d has a configuration similar to that of the settling tank 130 in FIG. 1. Water from the transfer pipe 115d flows into a region surrounded by the inflow baffle 111d. The advection baffle 112d moves the water in the settling tank 110d upward and guides it to a downstream water treatment tank (in this embodiment, the anaerobic treatment tank 130d). In this embodiment, water in the area surrounded by the advection baffle 112d flows into the anaerobic treatment tank 130d through an opening 113d formed in the second partition wall 202d between the water treatment tanks 110d and 130d. In the settling tank 110d, solids are settled and separated. The air diffuser 119d (hereinafter referred to as the settling tank air diffuser 119d) has multiple holes for discharging air bubbles and is located at the bottom of the settling tank 110d. The settling tank air diffuser 119d is used to agitate the water in the settling tank 110d (details will be described later).

[0146] The anaerobic treatment tank 130d is a water treatment tank that performs anaerobic treatment of wastewater using anaerobic microorganisms. The anaerobic treatment tank 130d has an inflow baffle 131d and an anaerobic filter bed 138d for retaining anaerobic microorganisms. The anaerobic filter bed 138d may have various shapes, such as a plate portion or a mesh portion. Water from the opening 113d is guided by the inflow baffle 131d to a portion lower than the anaerobic filter bed 138d. The water moves upward through the anaerobic filter bed 138d. The anaerobic microorganisms retained in the anaerobic filter bed 138d anaerobically treat the water passing through the anaerobic filter bed 138d. The anaerobically treated water flows into the aerobic treatment tank 140d through an opening 133d formed in a third partition wall 203d between the water treatment tanks 130d and 140d.

[0147] The aerobic treatment tank 140d is a water treatment tank that performs aerobic treatment of wastewater using aerobic microorganisms. The aerobic treatment tank 140d has an aerobic filter bed 148d for retaining the aerobic microorganisms and an aeration device 149d positioned lower than the aerobic filter bed 148d. The aerobic filter bed 148d may have various shapes, such as plate portions or mesh portions. The aeration device 149d has multiple holes for discharging air bubbles. Air is supplied to the aeration device 149d by a blower (not shown). The air bubbles discharged from the aeration device 149d agitate the water in the aerobic treatment tank 140d and supply oxygen to the water. The aerobic microorganisms attached to the aerobic filter bed 148d use the oxygen to perform aerobic treatment. Hereinafter, the aeration device 149d will also be referred to as the aerobic aeration device 149d. The fourth partition wall 204d between the water treatment tanks 140d and 150d defines an opening 143d at the bottom thereof. Aerobically treated water flows into the treatment water tank 150d through the opening 143d.

[0148] The treatment tank 150d is a water treatment tank that temporarily stores water. Water that flows into the treatment tank 150d through the opening 143d moves upward within the treatment tank 150d. Solids contained in the water descend and accumulate at the bottom. Water that rises to the water surface flows into the disinfection tank 160d through an opening 153d formed in the fifth partition wall 205d between the water treatment tanks 150d and 160d.

[0149] The disinfection tank 160d contains a disinfectant 161d, and disinfects the water that flows into the disinfection tank 160d with the disinfectant 161d. The disinfected water is transferred to the outside of the wastewater treatment device 100d through an opening 163d formed in the body 200d.

[0150] The wastewater treatment device 100d has two air lift pumps 310d and 320d. The transfer air lift pump 310d has a suction port 311d located in the lower section 110dL of the settling tank 110d. The lower section 110dL is below the intermediate water level WLMd. The intermediate water level WLMd is half the water level WL1d during normal operation of the settling tank 110d. The transfer air lift pump 310d transfers water from the bottom of the settling tank 110d to the top of the storage tank 120d. Solids deposited at the bottom of the settling tank 110d are transferred to the storage tank 120d by the transfer air lift pump 310d.

[0151] The circulating air lift pump 320d has a suction port 321d located at the bottom of the treatment tank 150d. The circulating air lift pump 320d transfers water from the bottom of the treatment tank 150d to the settling tank 110d. The water from the circulating air lift pump 320d flows into an area surrounded by an inlet baffle 111d. Solids that have accumulated at the bottom of the treatment tank 150d are transferred to the settling tank 110d by the circulating air lift pump 320d.

[0152] The storage tank 120d includes a filter medium 121d. The filter medium 121d may have various shapes, such as a plate portion or a mesh portion. Solids contained in the water transferred to the storage tank 120d may descend and reach the filter medium 121d. The filter medium 121d may capture the solids. Solids not captured by the filter medium 121d may accumulate at the bottom of the storage tank 120d. In this manner, the solids are separated in the storage tank 120d. The first partition wall 201d between the water treatment tanks 110d and 120d forms an opening 123d located at the water surface of the storage tank 120d. The water from which the solids have been separated flows into the settling tank 110d through the opening 123d. The water from the opening 123d flows into the area surrounded by the inlet baffle 111d.

[0153] Figure 12 is a schematic diagram of a wastewater treatment system 1000d of this example. The wastewater treatment system 1000d includes a wastewater treatment device 100d, a blower 700d, and a control device 600. The blower 700d may include various pumps, similar to the blower 700 (Figure 2). In addition to the components described in Figure 11, the wastewater treatment device 100d includes four valves 510d-540d and pipes 513d, 523d, 535d, 536d, and 590d.

[0154] Pipe 590d is a pipe to be connected to blower 700d (also referred to as blower pipe 590d). Blower 700d is connected to blower pipe 590d via outer pipe 710d provided outside wastewater treatment device 100d. Blower 700d supplies air to blower pipe 590d.

[0155] A pump air supply pipe 513d is connected to the transfer air lift pump 310d. The pump air supply pipe 513d is connected to a blower pipe 590d. A transfer valve 510d is provided on the flow path of the pump air supply pipe 513d.

[0156] Settling tank air diffuser 119d is connected to air diffusion supply pipe 523d. Air diffusion supply pipe 523d ​​is connected to blower pipe 590d. Agitation valve 520d is provided on the flow path of air diffusion supply pipe 523d.

[0157] An aerobic air diffusion air supply pipe 536d is connected to the aerobic air diffusion device 149d. The aerobic air diffusion air supply pipe 536d is connected to a blower pipe 590d. An aerobic valve 530d is provided on the flow path of the aerobic air diffusion air supply pipe 536d.

[0158] An aerobic pump air supply pipe 535d is connected to the circulation air lift pump 320d. The aerobic pump air supply pipe 535d is connected to a portion of the aerobic air diffusion air supply pipe 536d between the aerobic aeration device 149d and the aerobic valve 530d. A circulation valve 540d is provided on the flow path of the aerobic pump air supply pipe 535d. The circulation valve 540d is a manual valve. A user (for example, an administrator of the wastewater treatment system 1000d) can adjust the amount of water transferred per unit time by the circulation air lift pump 320d by adjusting the opening of the circulation valve 540d.

[0159] Each of the valves 510d, 520d, and 530d has an electrically controllable actuator (e.g., a solenoid). The valves 510d, 520d, and 530d are controlled by the control device 600. The state of each of the valves 510d, 520d, and 530d is controlled to either a closed state or an open state.

[0160] The hardware configuration of the control device 600 is the same as the hardware configuration of the control device 600 in Fig. 2. The nonvolatile storage device 630 stores a control program 631d. The processor 610 controls the valves 510d, 520d, and 530d in accordance with the control program 631d.

[0161] In this embodiment, the control process for the valves 510d, 520d, and 530d is a process obtained by replacing the valves 510, 520, and 530 in the control process of FIG. 3 with the valves 510d, 520d, and 530d, respectively.

[0162] In normal operation (S100), the aerobic aeration device 149d (FIGS. 11 and 12) and the circulation air lift pump 320d are in operation, while the settling tank aeration device 119d and the transfer air lift pump 310d are stopped.

[0163] In the first transfer process S120, the aerobic aeration device 149d, the circulation air lift pump 320d, and the settling tank aeration device 119d are stopped. The transfer air lift pump 310d transfers water from the settling tank 110d to the storage tank 120d. This may cause the water level in the settling tank 110d to drop. For example, if it takes a long time for the water to pass through the filter medium 121d in the storage tank 120d, the water level in the settling tank 110d will drop. Note that if the water transferred to the storage tank 120d can easily return to the settling tank 110d, the change in the water level will be small.

[0164] In the agitation process S140, the transfer air lift pump 310d is stopped. The settling tank aeration device 119d agitates the water in the settling tank 110d. As a result, the floating solids and the settling solids are agitated in the water treatment tank 110d.

[0165] In the settling process S160, the settling tank aeration device 119d and the transfer air lift pump 310d are stopped. The water is left stationary in the settling tank 110d. As a result, the agitated solids settle to the bottom of the settling tank 110d. Note that because the aerobic valve 530d is open, the blower 700d can continue to operate properly (the aerobic aeration device 149d and the circulation air lift pump 320d operate as in normal operation).

[0166] In the second transfer process S180, the transfer air lift pump 310d transfers water from the settling tank 110d to the storage tank 120d, whereby the solid matter that has settled at the bottom of the settling tank 110d is transferred to the storage tank 120d.

[0167] As described above, the wastewater treatment device 100d (FIG. 11) of this embodiment has a plurality of water treatment tanks 110d-160d, including a settling tank 110d configured to settle solids without filtering them, and a storage tank 120d configured to store solids.

[0168] A settling tank aeration device 119d is disposed within the settling tank 110d (FIG. 11) to agitate the water within the settling tank 110d. As shown in FIG. 12, an aeration air supply pipe 523d ​​is connected to the settling tank aeration device 119d. An agitation valve 520d is provided in the flow path of the aeration air supply pipe 523d. The agitation of the water by the settling tank aeration device 119d can be controlled by the agitation valve 520d. The settling tank aeration device 119d, the aeration air supply pipe 523d, and the agitation valve 520d together are an example of an agitation device (also referred to as agitation device 930d) configured to agitate the water within the settling tank 110d.

[0169] Transfer air lift pump 310d (FIG. 11) has a suction port 311d located within settling tank 110d. As shown in FIG. 12, transfer air lift pump 310d is connected to pump air inlet pipe 513d. Transfer valve 510d is provided in the flow path of pump air inlet pipe 513d. The transfer of water by transfer air lift pump 310d can be controlled by transfer valve 510d. The transfer air lift pump 310d, pump air inlet pipe 513d, and transfer valve 510d together are an example of a transfer device (also referred to as transfer device 940d) configured to transfer water from settling tank 110d to storage tank 120d.

[0170] The wastewater treatment system 1000d (FIG. 12) includes a control device 600 configured to control an agitation device 930d and a transfer device 940d. As described above, the control device 600 is configured to execute a specific process S900 based on the flowchart of FIG. 3. The specific process S900 includes an agitation process S140 and a transfer process S180. In this embodiment, the agitation process S140 includes an agitation process in which the agitation device 930d agitates the water in the settling tank 110d. The transfer process S180 includes a transfer process in which, after the agitation process S140, the transfer device 940d transfers water containing solids from the settling tank 110d to the storage tank 120d. According to this configuration, the settled solids and the floating solids in the settling tank 110d are agitated by the agitation process S140. Then, the transfer process S180 is performed after the agitation process S140. Therefore, the transfer device 940d can appropriately transfer solids including settled solids and floated solids. Furthermore, the settling tank 110d can continue separating solids even without the need for an operator to clean the settling tank 110d (for example, by removing the solids from the wastewater treatment device 100d).

[0171] In this embodiment, the agitation device 930d and the transfer device 940d are controlled in the same manner as in the first embodiment. Therefore, the wastewater treatment system 1000d of this embodiment has various advantages similar to the wastewater treatment system 1000. For example, the transfer air lift pump 310d of the transfer device 940d has a suction port 311d located in the lower portion 110dL of the settling tank 110d. The specific process S900 includes a settling process S160, which is performed after the agitation process S140 and before the second transfer process S180. The settling process S160 includes a settling process in which solids are allowed to settle in the settling tank 110d by stopping both the agitation by the agitation device 930d and the transfer by the transfer device 940d. With this configuration, the transfer air lift pump 310d of the transfer device 940d can transfer water with a high solid concentration in the second transfer process S180. Therefore, the total amount of water transferred by the transfer air lift pump 310d in one second transfer process S180 can be reduced. When the total amount of water transferred is small, the water flow generated by the transferred water in the storage tank 120d is weaker than when the total amount of water transferred is large. Therefore, the amount of solids flowing out from the storage tank 120d is reduced.

[0172] Furthermore, the control device 600 is configured to execute the specific process S900 once a day, which makes it possible to reduce the amount of solid matter remaining in the settling tank 110d compared to when the specific process S900 is executed less frequently.

[0173] The control program 631d of the control device 600 may be configured to execute a schedule determination process (FIG. 7) and a schedule execution process (FIG. 8). In this case, the control device 600 executes the specific process S900 N times per day (N is an integer equal to or greater than 1). Therefore, the amount of solids remaining in the settling tank 110d can be appropriately reduced. The control device 600 also allows the user to change the number of times per day, N, that the specific process S900 is executed. The user can adjust the number of times per day, N, that the specific process S900 is executed to match the inflow load of the wastewater treatment device 100d.

[0174] The specific process S900 (FIG. 3) includes a first transfer process S120 that is executed before the agitation process S140. The first transfer process S120 includes a process in which the transfer device 940d (FIG. 12) transfers water from the settling tank 110d to the storage tank 120d. With this configuration, the water level in the settling tank 110d may drop due to the transfer of water. Then, the agitation process (agitation process S140) in the settling tank 110d may be performed with the water level lowered. This reduces the possibility of solids overflowing from the settling tank 110d during the agitation process.

[0175] As shown in FIG. 11, the water treatment tanks 110d-160d of the wastewater treatment device 100d include a settling tank 110d. The wastewater treatment device 100d has a partition wall 201d that forms an opening 123d. The opening 123d is an example of a flow path connecting the storage tank 120d and the settling tank 110d. After solids are separated from the water transferred to the storage tank 120d, the water flows into the settling tank 110d through the opening 123d. This reduces the possibility of water overflowing from the storage tank 120d to the outside of the wastewater treatment device 100d. The settling tank 110d into which the water from the storage tank 120d flows is an example of a "target tank that is either a settling tank or a water treatment tank arranged upstream of the settling tank."

[0176] As shown in Figure 11, the multiple water treatment tanks 110d-160d of the wastewater treatment device 100d include an aerobic treatment tank 140d located downstream of the settling tank 110d. Water from which solids have been separated by the settling tank 110d flows into the aerobic treatment tank 140d. This reduces the load on the aerobic treatment tank 140d, allowing the aerobic treatment tank 140d to perform aerobic treatment appropriately. In this way, the wastewater treatment device 100d can treat wastewater appropriately.

[0177] E. Variations: (1) The control device 600 executes various processes in connection with the specific process S900 (FIG. 3). For example, the number of times N that the specific process S900 (FIG. 3) is executed per day may be any integer equal to or greater than 1. The start times of the N specific processes S900 may be predetermined, rather than determined by the user. The processes of FIGS. 7 and 8 may be applied to the embodiments of FIGS. 9 and 10. In this case, in the process of FIG. 7, the control device 600 may allow the user to determine N first start times T11 (FIG. 10) for the N specific processes. The control device 600 may allow the user to adjust each of the durations DT1, DT2, DT3, and DT4 of FIG. 4. The control device 600 may allow the user to adjust each of the waiting times DT11 and DT12 of FIG. 10. In the embodiment of FIG. 10, the order of the specific processes for the water treatment tanks 130, 140, and 160 may be any other order. For example, the control device 600 may execute the specific process in the order of the second filtration tank 160, the first filtration tank 140, and the settling tank 130. The control device 600 may stop the blowers 700 and 700d in the settling process S160.

[0178] (2) The process of transferring water containing solids from a water treatment tank that separates solids, such as a filtration tank or a sedimentation tank, to another water treatment tank may be various other processes instead of the specific process S900 (FIG. 3). For example, one or more processes arbitrarily selected from S120, S140, and S160 may be omitted.

[0179] (3) The multiple first carriers 148 in the first filtration tank 140 (FIG. 1) may have any configuration capable of capturing solid matter. For example, the first carriers 148 may be resin sponges. In order to separate solid matter from the first carriers 148 in the stirring process S140 (FIG. 3), it is preferable that the multiple first carriers 148 flow with the water when the water flows. For example, when the specific gravity of the first carriers 148 is greater than 1, the smaller the specific gravity, the more easily the first carriers 148 flow. Note that the specific gravity of the first carriers 148 may be large enough that the first carriers 148 do not flow when the water flows. Alternatively, the specific gravity of the first carriers 148 may be less than 1. In this case, it is preferable that the first filtration tank 140 has a member (for example, a mesh-like lid member) for preventing the multiple first carriers 148 from moving upward. The above description of the first filtration tank 140 and the anaerobic filter bed 138d may be applied to the second filtration tank 160 and the second filter carrier 168.

[0180] (4) The second carrier 168 of the second filtration tank 160 (FIG. 1) may be a carrier different from the first carrier 148 of the first filtration tank 140. For example, the first carrier 148 and the second carrier 168 may differ in one or more parameters, such as size, shape, specific gravity, material, etc. For example, the size of the second carrier 168 may be smaller than the size of the first carrier 148. In this case, the second filtration carrier 168 can easily capture small solids. Also, in this case, the volume V2 of the multiple second carriers 168 may be smaller than the volume V1 of the multiple first carriers 148.

[0181] (5) The filter tanks 140, 160 may have various other configurations instead of the configuration described above. For example, the first filtration unit 147 of the first filtration tank 140 may have a filter fixed to the filter tank, such as a mesh unit, instead of the multiple carriers 148. The second filtration unit 167 of the second filtration tank 160 may also have a filter. The filter of the second filtration tank 160 is preferably finer than the filter of the first filtration tank 140. In either case, the filtration tanks 140, 160 may be configured so that water moves downward through the filtration units 147, 167 during normal operation.

[0182] (6) The configuration of the wastewater treatment device is not limited to the configurations of the wastewater treatment devices 100, 100b, and 100d shown in Figures 1, 2, 9, and 11, and various other configurations may be used. For example, the configuration of the wastewater treatment device may be various configurations that include multiple water treatment tanks, including a first filtration tank (e.g., first filtration tank 140 (Figure 1)), an aerobic treatment tank (e.g., aerobic filter bed tank 150) located downstream of the first filtration tank, and a second filtration tank (e.g., second filtration tank 160) located downstream of the aerobic treatment tank. Here, the aerobic treatment tank preferably has a fixed bed.

[0183] The upstream configuration of the aerobic filter bed tank 150 (FIG. 1) may be any configuration including the first filtration tank 140. For example, one or more water treatment tanks arbitrarily selected from the water treatment tanks 110, 120, 130, and 190 may be omitted. In addition, an anaerobic treatment tank 130d (FIG. 11) may be provided between the impurity removal tank 130 and the first filtration tank 140, or between the first filtration tank 140 and the aerobic filter bed tank 150.

[0184] The circulating air lift pump 340 may transfer water to any water treatment tank upstream of the aerobic filter bed tank 150 or to the sludge storage tank 190. For example, the circulating air lift pump 340 may transfer water to the flow rate adjustment tank 120, the sludge storage tank 190, the impurity removal tank 130, or any of the above-mentioned anaerobic treatment tanks. Similarly, the first air lift pump 310 may transfer water to any water treatment tank upstream of the first filtration tank 140 or to the sludge storage tank 190. The second air lift pump 320 may transfer water to any water treatment tank upstream of the second filtration tank 160 or to the sludge storage tank 190. The settling tank air lift pump 330 may transfer water to any water treatment tank upstream of the settling tank 130 or to the sludge storage tank 190.

[0185] The downstream configuration of the aerobic filter bed tank 150 (FIG. 1) may be any configuration including a second filtration tank 160. For example, a treatment water tank for temporarily storing water may be provided between the aerobic filter bed tank 150 and the second filtration tank 160, or between the second filtration tank 160 and the disinfection tank 170. A circulating air lift pump 340 may transport water from this treatment water tank.

[0186] The wastewater treatment device may include various target transfer devices configured to transfer water from a first target tank to a second target tank, not limited to the second air lift pump 320 (FIG. 1) and the circulating air lift pump 340. Here, the first target tank is either an aerobic treatment tank (e.g., aerobic filter bed tank 150) or a water treatment tank located downstream of the aerobic treatment tank (e.g., second filtration tank 160 or any of the above-mentioned treated water tanks). The second target tank is either a first filtration tank (e.g., first filtration tank 140), a water treatment tank located upstream of the first filtration tank (e.g., water treatment tanks 110, 120, 130, or any of the above-mentioned anaerobic treatment tanks), a storage tank for storing solids (e.g., sludge storage tank 190), or an anaerobic treatment tank. Note that such target transfer devices may be omitted. For example, the circulating air lift pump 340 may be omitted.

[0187] (7) The wastewater treatment device may have various configurations, including multiple water treatment tanks including a settling tank and a storage tank, an agitation device configured to agitate the water in the settling tank, and a transfer device configured to transfer the water from the settling tank to the storage tank. Here, the settling tank is a water treatment tank configured to settle solids without filtering them (e.g., settling tank 130 (FIG. 1) or settling tank 110d (FIG. 11)). The storage tank is a water treatment tank configured to store solids (e.g., sludge storage tank 190 (FIG. 1) or storage tank 120d (FIG. 11)). For example, one or more water treatment tanks arbitrarily selected from water treatment tanks 110, 120, 140, 150, 160, 170, and 180 may be omitted from the wastewater treatment device 100 of FIG. 1. Furthermore, one or more water treatment tanks arbitrarily selected from water treatment tanks 130d-160d may be omitted from the wastewater treatment device 100d of FIG. 11.

[0188] The settling tank may have various configurations that allow solids to settle, and is not limited to a configuration having an inflow baffle (e.g., inflow baffle 131, 111d (FIGS. 1 and 11)) and an advection baffle (e.g., advection baffle 132, 112d (FIGS. 1 and 11)). For example, one or both of the inflow baffle and the advection baffle may be omitted. The settling tank may be configured so that water flows into the top and flows out from an opening provided at the bottom. The tank may be configured so that water flows in through an opening at the bottom and flows out through an opening at the water surface. The settling tank may have a weir that advects water without advecting solids. The storage tank may be configured in various ways that can store solids, instead of the configuration with inflow baffle 191 (FIG. 1) and advection baffle 192 and the configuration with filter media 121d (FIG. 11). For example, the inflow baffle 191 and advection baffle 192 of the sludge storage tank 190 (FIG. 1) may be configured in various ways that can store solids. One or both of the filter 192 and the filter media 121d of the reservoir 120d (FIG. 11) may be omitted. The reservoir 120d may be provided with an inflow baffle, an advection baffle, or both. The reservoir may be configured so that water flows into the top and flows out from an opening provided in the bottom. The reservoir may be configured so that water flows in from an opening provided in the bottom and flows out from an opening provided at the water surface. The reservoir may be The storage tank may have a weir that advects water without advecting solids. The storage tank is preferably a water treatment tank into which water does not flow when no process (e.g., specific process S900 in FIG. 3) is being performed to transfer water from the settling tank to the storage tank, like the sludge storage tank 190 (FIG. 1) and storage tank 120d (FIG. 11) described above. However, the storage tank may also be a water treatment tank into which water flows for wastewater treatment when no process is being performed to transfer water from the settling tank to the storage tank.

[0189] The water level of the settling tank during normal operation may fluctuate according to the amount of wastewater per unit time flowing into the wastewater treatment device. In this case, the lower portion of the settling tank (e.g., portion 130 L (FIG. 1) or 110 dL (FIG. 11)) may be at a water level below half the maximum water level for which the settling tank is designed.

[0190] In either case, the control device 600 is preferably configured to execute specific processes including an agitation process and a transfer process. Here, the agitation process is a process in which the agitation device agitates the water in the settling tank. The transfer process is a process in which the transfer device transfers the water containing solids from the settling tank to the storage tank after the agitation process. This allows the settling tank to continue separating solids without the need for an operator to clean the settling tank (for example, by removing the solids outside the wastewater treatment device).

[0191] (8) The fixed bed installed in the aerobic treatment tank may be various members fixed to the wall that forms the aerobic treatment tank. The aerobic treatment tank may have multiple carriers that flow with the water.

[0192] (9) The wastewater treatment device has various flow paths connecting two water treatment tanks. For example, the opening 193 formed in the second partition wall 202 (FIG. 1) is an example of a flow path connecting the sludge storage tank 190 and the flow rate adjustment tank 120. The flow path forming portion that forms the flow path is not limited to a wall such as the second partition wall 202, but may be any member such as a pipe or a gutter.

[0193] (10) The device for transferring water may include other types of pumps (e.g., electric pumps) instead of air lift pumps. The device for agitating water in a water treatment tank may include other types of devices instead of air diffusers. For example, an agitator having a screw and a motor for rotating the screw may be used. A pump for transferring water from a first position to a second position in a water treatment tank may be used.

[0194] (11) The arrangement of the multiple water treatment tanks within the body may be any arrangement. For example, two or more water treatment tanks may be arranged side by side in the width direction of the body. Furthermore, the multiple water treatment tanks may be distributed among multiple bodies. In this way, the wastewater treatment device may have multiple bodies.

[0195] (12) The control device 600 (FIGS. 2 and 12) may be various computers (for example, personal computers) instead of a PLC.

[0196] In each of the above embodiments, a part of the configuration realized by hardware may be replaced by software, and conversely, a part or all of the configuration realized by software may be replaced by hardware. For example, the control device 600 may include a dedicated hardware circuit that executes the function of the specific process S900 in FIG. 3.

[0197] Furthermore, when some or all of the functions of the present invention are realized by a computer program, the program can be provided in a form stored on a computer-readable recording medium (e.g., a non-transitory recording medium). The program can be used while stored on the same or a different recording medium (computer-readable recording medium) from when it was provided. The "computer-readable recording medium" is not limited to portable recording media such as memory cards and CD-ROMs, but can also include internal storage devices within a computer, such as various ROMs, and external storage devices connected to a computer, such as a hard disk drive.

[0198] The present invention has been described above based on examples and modifications, but the above-described embodiments of the invention are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit of the invention, and equivalents thereof are also included within the scope of the present invention. [Explanation of symbols]

[0199] 100, 100b, 100d... Wastewater treatment device, 110... Aeration type screen, 110d... Sedimentation tank, 111... Screen, 111d... Inflow baffle, 112d... Advection baffle, 113, 113d... Opening, 115d... Transfer pipe, 119d... Aeration device (sedimentation tank aeration device), 120... Flow rate adjustment tank, 120d... Storage tank, 121... Pump, 121d... Filter material, 122... Metering adjustment device, 123... Transfer pipe, 123d... Opening, 130... Sedimentation tank (impurity removal tank), 130d... Anaerobic treatment tank, 131, 131d... Inflow baffle, 132... Advection baffle, 133, 133d... Opening, 1 38d...Anaerobic filter bed, 139...Settling tank aeration device, 140...First filtration tank, 140d...Aerobic treatment tank, 141...Inflow baffle, 143, 143d...Opening, 146...First support part, 147...First filtration part, 148...First carrier (first filtration carrier), 148d...Aerobic filter bed, 149...First aeration device, 149d...Aerobic aeration device, 150...Aerobic filter bed tank, 150d...Treatment water tank, 153, 153d...Opening, 158...Filter bed, 159...Aerobic aeration device, 160...Second filtration tank, 160d...Disinfection tank, 161...Inflow baffle, 161d...Disinfectant, 163, 163d...Opening, 166...Second support part, 1 67...second filtration section, 168...second carrier (second filtration carrier), 169...second air diffuser, 170...disinfection tank, 171...disinfectant, 173...opening, 180...discharge pump tank, 181...discharge pump, 190...sludge storage tank, 191...inflow baffle, 192...advection baffle, 193...opening, 200, 200d...body, 201, 201d...first partition wall, 202, 202d...second partition wall, 203, 203d...third partition wall, 204, 204d...fourth partition wall, 205, 205d...fifth partition wall, 206...sixth partition wall, 207...seventh partition wall, 208...eighth partition wall, 310...first air air lift pump, 310d...transfer air lift pump, 311...first suction port, 311d...suction port, 320...second air lift pump (target transfer device), 320d...circulating air lift pump, 321...second suction port, 321d...suction port, 330...settling tank air lift pump, 331...third suction port, 340...circulating air lift pump, 341...suction port, 390...transfer pipe, 431, 432, 433, 441, 461...solids, 510...first valve (transfer valve), 510a...first transfer valve, 510b...second transfer valve, 510c...third transfer valve, 510d...transfer valve,511...first auxiliary pump air supply pipe, 512...second auxiliary pump air supply pipe, 513...third auxiliary pump air supply pipe, 513d...pump air supply pipe, 517...pump connecting pipe, 518...main pump air supply pipe, 519...first connecting pipe, 520...second valve (agitation valve), 520a...first agitation valve, 520b...second agitation valve, 520c...third agitation valve, 520d...agitation valve, 521...first auxiliary aeration air supply pipe, 522... Second sub-aeration air supply pipe, 523...Third sub-aeration air supply pipe, 523d...Aeration air supply pipe, 527...Aeration connection pipe, 528...Main aeration air supply pipe, 529...Second connection pipe, 530, 530d...Aerobic valve, 535, 535d...Aerobic pump air supply pipe, 536, 536d...Aerobic diffusion air supply pipe, 540, 540d...Circulation valve, 590, 590d...Blower pipe, 600...Control device, 610...Processor, 620...Volatile storage device, 630... Nonvolatile storage device, 631, 631b, 631d...control program, 640...output device, 650...input device, 690...interface, 700, 700d...blower, 710, 710d...outer pipe, 910...first transfer device, 920...agitation device, 930, 930b...settling tank agitation device, 930d...agitation device, 940, 940b...second transfer device, 940d...transfer device, 1000, 1000b, 1000d...wastewater treatment system

Claims

1. A wastewater treatment system comprising: a plurality of water treatment tanks including a settling tank configured to settle solids without filtering the solids, and a storage tank configured to store the solids; an agitator configured to agitate the water in the settling tank; a transfer device configured to transfer water from the settling tank to the reservoir; a control unit configured to control the stirring device and the transfer device; Equipped with The control unit a stirring process in which the stirring device stirs the water in the settling tank; a transfer process in which, after the stirring process, the transfer device transfers the water containing solids from the settling tank to the storage tank; configured to perform a specific process including the transfer device has a suction port located in a lower portion of the settling tank; The specific treatment is a treatment performed after the stirring treatment and before the transfer treatment, and includes a precipitation treatment in which solid matter is precipitated in the settling tank by stopping both the stirring by the stirring device and the transfer by the transfer device. Wastewater treatment system.

2. The wastewater treatment system according to claim 1, The control unit is configured to execute the specific process N times (N is an integer equal to or greater than 1) per day. Wastewater treatment system.

3. The wastewater treatment system according to claim 2, the control unit is configured to allow a user to change the number of times N per day that the specific process is performed. Wastewater treatment system.

4. The wastewater treatment system according to any one of claims 1 to 3, The specific treatment includes a treatment of causing the transfer device to transfer water from the settling tank to the storage tank before the stirring treatment. Wastewater Treatment System

5. The wastewater treatment system according to any one of claims 1 to 4, The plurality of water treatment tanks include a target tank that is either the settling tank or a water treatment tank arranged upstream of the settling tank, The wastewater treatment system has a flow path connecting the storage tank and the target tank. Wastewater treatment system.

6. The wastewater treatment system according to any one of claims 1 to 5, The plurality of water treatment tanks includes an aerobic treatment tank located downstream of the settling tank. Wastewater treatment system.

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