Deodorization system, deodorization device, and deodorization method

Abstract

To provide a deodorization system capable of reducing a cost related to deodorization and reliably determining whether or not odor leaks from the inside of a tank.SOLUTION: A deodorization system includes a container 21 for storing water to be treated, a deodorization fan 31 for sucking in gas from inside the container 21, an anemoscope 23 for detecting a wind direction detection signal Sd indicating the state of the gas inside the container, and a suction control part 30 for changing a suction amount of the deodorization fan 31 based on the gas information. The deodorization system may use an anemometer 53 or a pressure gauge 73 instead of the anemoscope 23.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an odor prevention system, an odor prevention device, and an odor prevention method for preventing odors from diffusing to the outside in facilities that treat sewage or rainwater. [Background technology]

[0002] Wastewater (hereinafter referred to as "sewage") resulting from or associated with daily life or businesses other than farming flows into sewage pipes or, together with rainwater, into sewer pipes and reaches, for example, a sewage treatment plant. The sewage is purified at the sewage treatment plant and then discharged as treated water into rivers or the sea. A sewage treatment plant has a settling tank where the sewage settles to remove garbage, and an aeration tank where the sewage is exposed to air (aerated) and supplied with air to promote the decomposition of pollutants by microorganisms. Odors generated by the aeration tank or settling tank are sucked in by a deodorizing fan through a duct and, as necessary, directed to a deodorizing device for treatment.

[0003] A known technique for controlling odors in sewage treatment plants is described, for example, in Patent Document 1. The deodorizing control system described in Patent Document 1 is equipped with an odor sensor in a building where an odor source is located, and controls the intake of outside air into the building or the air inside the building to be led to a deodorizing device and then discarded, depending on the concentration and type of odor detected by the odor sensor. Patent Document 1 also describes controlling the air flow inside the building by opening and closing dampers installed in ducts. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-17976 Summary of the Invention [Problem to be solved by the invention]

[0005] In such sewage treatment plants, as a countermeasure against odor leakage from the aeration tank to the surrounding area, the deodorizing fan is controlled to always draw air from the aeration tank at a volume equal to or greater than the maximum aeration air volume (air supply volume). Meanwhile, the dissolved oxygen (DO) in the aeration tank is a factor that affects the state of microorganisms and varies depending on the level of pollution of the wastewater and the amount of water flowing into it. The aeration air volume is increased or decreased to maintain the amount of dissolved oxygen necessary to suppress odors. For this reason, excessive air may be drawn into the aeration tank. To reduce the power consumption and costs associated with sewage treatment plants, it is preferable to prevent the deodorizing fan from drawing in excessive air and to reduce the power supplied to the deodorizing fan.

[0006] However, the deodorizing control system described in Patent Document 1 controls the fan to either bring in outside air into the building or release it to the outside through the deodorizing device depending on the odor, so no consideration is given to reducing the power required by the fan.

[0007] Furthermore, facilities that generate odors are not limited to sewage treatment plants; odors may also be generated outside sewage treatment plants by other factories, compost, etc. In such cases, the odor control system of Patent Document 1 has the problem that it is difficult to determine whether the odor in the environment is caused by the sewage treatment plant or other factors when drawing air from the outside into the building or when discharging air to the outside via a deodorizing device.

[0008] The present invention has been made in consideration of these points, and relates to an odor prevention system, an odor prevention device, and an odor prevention method that reduce the cost of odor prevention by saving power and can reliably determine whether or not odor is leaking from inside a tank. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, one form of the odor prevention system of the present invention includes a container for storing the water to be treated, an intake fan for drawing in gas from inside the container, a gas state detection unit for detecting gas information indicating the state of the gas inside the container, and an intake control unit for changing the amount of air drawn in by the intake fan based on the gas information.

[0010] One embodiment of the odor deodorization device of the present invention includes a gas state detection unit that detects gas information indicating the state of gas inside a container that holds the water to be treated, and an intake control unit that changes the intake volume of an intake fan that draws in gas inside the container based on the gas information.

[0011] One form of the deodorizing method of the present invention includes a step of detecting gas information indicating the state of gas inside a container that holds the water to be treated, and a step of changing the intake volume of an intake fan that draws in gas inside the container based on the gas information. [Effects of the Invention]

[0012] According to the above-described embodiments, it is possible to provide an odor prevention system, an odor prevention device, and an odor prevention method that can reduce the costs associated with odor prevention and reliably determine whether or not an odor is leaking from inside the tank. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram illustrating an environment including a sewage treatment plant to which a deodorizing system according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a schematic diagram for explaining an odor prevention system provided in the aeration tank of the first embodiment. [Figure 3] FIG. 3 is a diagram for explaining the intake control section. [Figure 4] 3 is a flowchart illustrating a deodorization method performed by the deodorization device of the first embodiment. [Figure 5] FIG. 10 is a schematic diagram for explaining an odor prevention system provided in the aeration tank of the second embodiment. [Figure 6]10 is a flowchart illustrating a deodorization method performed by a deodorization device according to a second embodiment. [Figure 7] FIG. 10 is a schematic diagram for explaining an odor prevention system provided in the aeration tank of the third embodiment. [Figure 8] 10 is a flowchart illustrating a deodorization method performed by a deodorization device according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a first embodiment, a second embodiment, and a third embodiment of the present invention will be described with reference to the drawings (the first embodiment, the second embodiment, and the third embodiment will also be collectively referred to as "the present embodiment"). However, the drawings used in the description of the present embodiment are intended to explain the configuration, function, action, effect, and technical concept of the present embodiment, and the specific shape and design are not limited by the drawings.

[0015] FIG. 1 is a diagram illustrating an environment 1 including a sewage treatment plant to which the deodorizing system of this embodiment is applied. The environment 1 includes a sewage manhole 5 that collects sewage from homes, factories, etc., and sewer pipes 7 and 8 that guide the sewage flowing out of the sewage manhole 5 to the sewage treatment plant. The sewer pipes 7 and 8 are provided with sewage manholes 6. The sewage treatment plant also includes a purification facility A, a chlorine mixing tank 13 that sterilizes pathogenic bacteria in the sewage (purified water) purified by the purification facility A, and a sludge treatment facility 15 that treats the sludge removed by the purification facility A. The purification facility A includes a grit basin 9, a primary sedimentation tank 10, an aeration tank 11, and a final sedimentation tank 12. The grit basin 9 receives sewage and removes relatively large debris and sand. The primary sedimentation tank 10 receives sewage flowing in from the grit basin 9 and removes smaller debris and sand. The wastewater flows at a relatively slow rate through the primary sedimentation tank 10, during which time trash and sand settle to the bottom of the tank. The wastewater then flows into the aeration tank 11.

[0016] The aeration tank 11 mixes activated sludge with the wastewater flowing in from the primary sedimentation tank 10. Activated sludge is a group of bacteria, fungi, protozoa, and metazoa, and it is believed that these diverse organisms live in a symbiotic and predatory relationship with one another. The wastewater is purified in the aeration tank 11 by supplying oxygen to the wastewater (aeration) along with the activated sludge, and by utilizing the fact that organic matter and some inorganic salts are necessary for the metabolism of microorganisms. The wastewater is purified by oxidative decomposition or absorption and separation of pollutants. The activated sludge used for purification is in a state that makes it easy to settle.

[0017] The purified wastewater and activated sludge flow into the final settling tank 12. The activated sludge settles as it passes through the final settling tank 12 and is separated from the wastewater. Some of the settled activated sludge is returned to the aeration tank 11, and the remaining sludge is transported to a sludge treatment facility 15. The treated water separated in the final settling tank 12 enters the chlorine mixing tank 13, where it is mixed with sodium hypochlorite and subjected to a sterilization treatment of pathogenic bacteria. The purified water after sterilization is discharged into a river or other public water body.

[0018] (First embodiment) FIG. 2 is a schematic diagram illustrating an odor prevention system provided in the aeration tank 11 of the first embodiment. The aeration tank 11 includes a plurality (n) of containers 21a to 21n (hereinafter, also referred to as containers 21 when there is no need to distinguish between them), and each container 21 includes a tank-shaped main body and a lid (not shown) that covers the main body. The aeration tank 11 includes a facility that houses the plurality of containers, and the containers 21 are installed under or on the floor within the facility. FIG. 2 shows an example in which the containers 21 are installed under the floor U. In this embodiment, the wastewater stored in the containers 21 is referred to as water to be treated. The containers 21 are not limited to being installed indoors, but may also be installed outdoors, and even outdoors, they may be installed above or below ground.

[0019] The purification system of this embodiment includes a vessel 21 that contains water to be treated, a deodorizing fan 31 (FIG. 3) that draws in gas from inside vessel 21, anemometers 23a to 23n (hereinafter, also referred to as anemometer 23 when there is no need to distinguish between them) that function as a gas state detection unit that detects gas information that indicates the state of the gas inside vessel 21, and an intake control unit 30 (FIG. 3) that changes the amount of air intake by the deodorizing fan based on the gas information. Vessel 21 contains water w to be treated, and above w is space a where gas exists. Pipes 25a to 25n (hereinafter, also referred to as pipe 25 when there is no need to distinguish between them) and the end of duct 29 are inserted into the spaces a of vessels 21 to 21n, respectively.

[0020] Pipe 25 has a ventilation function that connects space a inside container 21 with space F outside container 21. Note that the structure that connects the inside and outside of container 21 is not limited to having a pipe shape, and may be, for example, an opening provided in a lid (not shown) that covers container 21.

[0021] Pipes 25a to 25n are provided with wind vanes 23a to 23n, respectively. Wind vane 23 may be, for example, a digital wind vane that electronically measures wind direction using a sensor. Wind vane 23 may also be a sensor that has the function of measuring wind speed. Wind direction detection signals Sd detected by wind vanes 23a to 23n are input to intake control unit 30. Note that the first embodiment is not limited to including such sensors, and may also include, for example, other odor sensors.

[0022] One end of duct 29 is inserted into each of containers 21a to 21n, and the other end is connected to deodorizing fan (intake fan) 31. Deodorizing fan 31 draws in the gas that has passed through duct 29 and discharges it from duct 29. The discharged gas passes through a deodorizing tower (not shown) where it is purified and then released into the atmosphere. The deodorizing tower may be, for example, a packed biological deodorizing tower in which a microorganism-filled carrier is packed in a packed tower, or may be configured in combination with an activated carbon adsorption tower or soil deodorizing equipment.

[0023] Duct 29 is connected to deodorizing fan 31 and includes a trunk 29a through which gas from containers 21a to 21n flows, and branch portions 29b through which gas from each of containers 21a to 21n flows. Dampers 27a to 27n (hereinafter also referred to as dampers 27 when there is no need to distinguish between them) are provided between trunk 29a and branch portions 29b of duct 29, respectively, and adjust the amount of intake air taken in from containers 21a to 21n by changing the intake amount of deodorizing fan 31. Intake control unit 30 controls the opening degree of dampers 27a to 27n as well as the intake amount of deodorizing fan 31. At this time, intake control unit 30 outputs control signals to dampers 27a to 27n instructing the opening degree, and receives an ACK signal.

[0024] FIG. 3 is a diagram illustrating the intake control unit 30. The intake control unit 30 functions as the deodorization device of this embodiment. The intake control unit 30 receives wind direction detection signals Sd from each of the wind vanes 23a to 23n. The intake control unit 30 controls the amount of intake air by the deodorizing fan 31 by controlling the power supplied to the deodorizing fan 31 based on the wind direction indicated by the wind direction detection signals Sd. Furthermore, the intake control unit 30 controls the opening degrees of the dampers 27a to 27n based on each of the wind vanes 23a to 23n. A control signal Sc1 is a signal used by the intake control unit 30 to control the deodorizing fan 31. A control signal Sc2 is a signal used by the intake control unit 30 to control the opening degrees of the dampers 27a to 27n.

[0025] In this embodiment, "power control" includes not only control to increase or decrease the power (current, voltage) supplied to the deodorizing fan 31, but also control of the rotation frequency of the deodorizing fan 31, thereby increasing or decreasing the power consumed by the deodorizing fan 31.

[0026] Next, the control of the intake control unit 30 will be described. The wind direction detection signal Sd, which indicates the flow of gas from container 21 to space F, indicates that odors within container 21 are leaking to the outside. In such a case, intake control unit 30 outputs a control signal Sc1 to increase the amount of power supplied to deodorizing fan 31 (fan rotation speed). By increasing the amount of power supplied to deodorizing fan 31, the pressure within container 21 decreases and becomes lower than the pressure in space F. As the inside of container 21 enters a reduced pressure state, odor leakage to space F stops and gas begins to flow from space F into container 21. For example, intake control unit 30 further adjusts the amount of power supplied to deodorizing fan 31 from this state, maintaining the intake volume at a state where the flow of gas from space F into container 21 is stopped or minimized. This control makes it possible to supply the deodorizing fan 31 with the minimum amount of power necessary to prevent odor leakage, depending on the state of the gas within container 21.

[0027] Furthermore, in the first embodiment, a plurality of wind direction detection signals Sd are input to the intake control unit 30 from each of the plurality of anemometers 23a to 23n. For example, when a gas leak is detected in a predetermined number of containers 21 from the plurality of wind direction detection signals, the intake control unit 30 may increase the amount of power supplied to the deodorizing fan 31 until the wind direction of all of the containers 21 is directed from the space F into the containers 21. The predetermined number may be, for example, one or more. The containers 21 and the deodorizing fans 31 may be provided in a one-to-one correspondence, and each deodorizing fan 31 may draw air into the corresponding container 21, or one deodorizing fan 31 may draw air into multiple containers 21. Furthermore, in the first embodiment, a weight may be assigned to each container 21, and the amount of power supplied to the deodorizing fan 31 may be controlled by giving priority to the wind direction detection signal Sd of that container 21. This type of control is performed, for example, when a pit-shaped container 21 is installed from the primary sedimentation tank 10 toward the final sedimentation tank 12, and a plurality of wind vanes 23 are provided in the direction of flow of the container 21. In the first embodiment, based on the idea that the degree of pollution of wastewater is reduced downstream of the container 21 compared to upstream, it is considered that the wind direction detection signal Sd of the wind vane 23 installed upstream is given priority.

[0028] Furthermore, in the first embodiment, when the amount of intake air from the containers 21a to 21n is individually controlled, the intake control unit 30 outputs a control signal Sc1 to the dampers 27a to 27n to individually control the opening degrees of the dampers 27a to 27n. Such control, for example, sets the opening degree of the damper 27 to the maximum, and increases the supply power until all of the wind direction detection signals Sd indicate that the wind is heading from the space F toward the container 21. Then, the opening degree of the damper 27 of the container 21 whose wind direction detection signal Sd indicates that the wind is heading from the space F toward the container 21 is reduced. In this way, excessive air can be prevented from flowing into the container 21 from the space F, and the amount of intake air from within the container 21 can be suitably maintained.

[0029] FIG. 4 is a flowchart illustrating the deodorization method performed by the deodorization device of the first embodiment. As shown in FIG. 4, the intake control unit 30 determines whether the wind direction detection signal Sd indicates a wind direction from the container 21 to the space F (outside the tank → inside the tank) (step S401). In step S401, if the wind direction detection signal Sd indicates a wind direction from outside the tank to inside the tank (step S401: YES), the intake control unit 30 controls the amount of power supplied to the deodorizing fan 31 so as to reduce the amount of intake air (step S405). Next, the intake control unit 30 determines whether the wind direction detection signal Sd indicates no movement of gas between the container 21 and the space F (outside the tank = inside the tank) (step S402). In step S402, if the wind direction detection signal Sd indicates no movement of gas between the outside and inside the tank (step S402: YES), the intake control unit 30 controls the amount of power supplied to the deodorizing fan 31 so as to maintain the amount of intake air (step S406).

[0030] Furthermore, the intake control unit 30 determines whether the wind direction detection signal Sd indicates a wind direction from the space F to the container 21 (inside the tank → outside the tank) (step S403). In step S403, if the wind direction detection signal Sd indicates a wind direction from inside the tank to outside the tank (step S403: YES), the intake control unit 30 increases the amount of power supplied to the deodorizing fan 31 so as to increase the amount of intake air (step S407).

[0031] In the first embodiment, the wind direction detection signal Sd is detected at regular time intervals. Therefore, the intake control unit 30 determines whether the next detection time has arrived (step S404). The intake control unit 30 waits until the detection time (step S404: NO), and when the detection time arrives (step S404: YES), the intake control unit 30 returns to step S401 and inputs the wind direction detection signal Sd. However, the first embodiment is not limited to inputting the wind direction detection signal Sd at regular time intervals, and the wind direction detection signal Sd may be input continuously to control the amount of power supplied to the deodorizing fan 31.

[0032] The above-described deodorizing method is executed by a program running on a computer. The computer realizes the deodorizing method by using known hardware such as a CPU (Central Processing Unit), memory, and communication unit in cooperation with the program.

[0033] The odor prevention system, odor prevention device, and odor prevention method of the first embodiment described above controls the amount of intake air by increasing or decreasing the amount of power supplied to the deodorizing fan 31 (fan rotation speed) depending on the state of odor leakage. As a result, the first embodiment can reduce the costs associated with odor prevention. Furthermore, the first embodiment detects odor leakage from the containers 21 by measuring the wind direction between the containers 21 and the space F. As a result, the first embodiment can reliably detect odor leakage from each container 21 to the space F. Even when an odor is present in the environment, the first embodiment can determine whether the odor is caused by wastewater treatment or some other cause.

[0034] (Second embodiment) Next, a second embodiment will be described. In the drawings used in the second embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and some of the descriptions thereof will be omitted.

[0035] FIG. 5 is a schematic diagram for explaining the deodorizing system of the second embodiment. The deodorizing system of the second embodiment includes n containers 21. A pipe 25 and a branch portion 29b of a duct 29 are inserted into each container 21. The branch portion 29b allows the air to be aspirated by a deodorizing fan 31 through a trunk portion 29a to pass through. A damper 27 is provided between the trunk portion 29a and the branch portion 29b.

[0036] A wind speed meter 53a to a wind speed meter 53n (hereinafter also referred to as a wind speed meter 53 when it is not necessary to distinguish each of them) is provided in each of the pipes 25 of each container 21. The wind speed meter 53 is not particularly limited, and for example, an ultrasonic wind speed meter, a Pitot tube wind speed meter, a hot wire wind speed meter, or a laser wind speed meter can be considered. The second embodiment outputs a wind speed detection signal Se detected by the wind speed meter 53 to an intake control unit 30. The intake control unit 30 compares the wind speed detection signal Se with a preset wind speed threshold value Vth1, threshold value Vth2, and threshold value Vth3 (Vth1 < Vth2). The intake control unit 30 controls the amount of electric power supplied to the deodorizing fan 31 according to the result of comparison between the threshold values Vth1, Vth2 and the wind speed.

[0037] Note that the wind speed meter 53 is a device that measures the wind speed in a predetermined direction (for example, the direction from the space F to the container 21), and the wind speed in the opposite direction may be 0 or may indicate an error. The threshold value Vth3 of the second embodiment is a numerical value indicating that the wind speed is 0 or an error. However, the second embodiment is not limited to such a configuration, and a wind direction meter may be provided together with the wind speed meter 53.

[0038] FIG. 6 is a flowchart for explaining a deodorizing method performed by the deodorizing device of the second embodiment. The flowchart shown in FIG. 6 shows an example in which the wind speed meter 53 measures the wind speed from the space F toward the container 21. The intake control unit 30 determines whether the wind speed detection signal Se is greater than the wind speed threshold value Vth1 and less than the threshold value Vth2 (Vth1 < wind speed < Vth2) (step S601). In step S601, when the wind speed detection signal Se is greater than the threshold value Vth1 and less than the threshold value Vth2 (step S601: YES), the intake control unit 30 controls the power supply amount to the deodorizing fan 31 so that the intake air volume is maintained (step S606). Next, the intake control unit 30 determines whether the wind speed detection signal Se is greater than the threshold value Vth2 (step S602). In step S602, when the wind speed detection signal Se is greater than the threshold value Vth2 (step S602: YES), the intake control unit 30 decreases the power supply amount to the deodorizing fan 31 so that the intake air volume decreases (step S607).

[0039] In step S602, when the wind speed detection signal Se is not greater than the threshold value Vth2 (step S602: NO), the intake control unit 30 determines whether the wind speed detection signal Se is less than the threshold value Vth1 (step S603). In step S603, when the wind speed detection signal Se is less than the threshold value Vth1 (step S603: YES), the intake control unit 30 increases the power supply amount to the deodorizing fan 31 so that the intake air volume increases (step S608). Further, the intake control unit 30 determines whether the wind speed detection signal Se matches Vth3, that is, whether it corresponds to 0 or an error (step S604). As described above, 0 or an error is a numerical value indicating that the wind direction has reversed. When the wind speed detection signal Se indicates 0 or an error (step S604: YES), assuming that the gas flow from the container 21 to the space F has reversed, the intake control unit 30 increases the power supply amount to the deodorizing fan 31 so that the intake air volume increases (step S608).

[0040] In the second embodiment, the wind speed detection signal Se is detected at regular time intervals. Therefore, the intake control unit 30 determines whether the next detection time has arrived (step S604). The intake control unit 30 waits until the detection time (step S604: NO), and when the detection time arrives (step S604: YES), the process returns to step S601 and inputs the wind speed detection signal Se. Note that, even in the second embodiment, the wind speed detection signal Se may be input continuously.

[0041] In the second embodiment, the intake control unit 30 may input multiple wind speed detection signals Se and increase the intake volume of the deodorizing fan 31 until odor leakage is no longer detected in all of the containers 21. Furthermore, in the second embodiment, instead of controlling the intake volume of each of the multiple deodorizing fans 31 for the corresponding container, the intake volume of a single deodorizing fan may be controlled for multiple containers 21. In such a case, the second embodiment may control the intake volume of the deodorizing fan 31 by comparing the average value of the wind speeds indicated by the multiple wind speed detection signals Se with a predetermined threshold. Furthermore, in the second embodiment, weights may be assigned to the multiple containers 21, and the value indicated by the wind speed detection signal Se corresponding to the container 21 with the greater weight may be given priority.

[0042] The odor prevention system, odor prevention device, and odor prevention method of the second embodiment described above detect the state of odor leakage and increase or decrease the amount of power supplied to the deodorizing fan 31 to control the amount of intake air. Therefore, the first embodiment can reduce the costs associated with odor prevention. Furthermore, the second embodiment detects the amount of gas flowing into the container 21 from the outside by measuring the wind speed (in one direction) between the container 21 and the space F. Furthermore, because it can detect a reversal of the air flow direction, it can reliably detect odor leakage from each container 21 into the space F. Even when an odor is present in the environment, the second embodiment can determine whether the odor is caused by sewage treatment or some other cause.

[0043] (Third embodiment) Next, a third embodiment will be described. The drawings used in the third embodiment show the same configurations as those in the first and second embodiments with the same reference numerals, and the description thereof is partially omitted.

[0044] FIG. 7 is a schematic diagram for explaining the deodorizing system of the third embodiment. The deodorizing system of the third embodiment includes n containers 21. A pipe 25 and a branch portion 29b of a duct 29 are inserted into each container 21. The branch portion 29b allows the air to be aspirated by the deodorizing fan 31 through the trunk portion 29a to pass therethrough. A damper 27 is provided between the trunk portion 29a and the branch portion 29b.

[0045] A pressure gauge 73a to a pressure gauge 73n (hereinafter also referred to as a pressure gauge 73 when there is no need to distinguish each of them) is provided in each of the pipes 25 of each container 21. The pressure gauge 73 is not particularly limited, and for example, a mechanical pressure gauge, a differential pressure gauge, a manometer, a valve type pressure gauge, a differential pressure transmitter, etc. can be considered. The third embodiment outputs a pressure detection signal Sf detected by the pressure gauge 73 to the intake control unit 30. The intake control unit 30 compares the pressure detection signal Sf with a preset pressure threshold value Pth1 and a threshold value Pth2 (Pth1 < Pth2). The intake control unit 30 controls the amount of electric power supplied to the deodorizing fan 31 according to the result of comparison between the threshold values Pth1 and Pth2 and the pressure indicated by the pressure signal Sf. However, the third embodiment is not limited to providing the pressure gauge 73 in the pipe 25, and the pressure gauge 73 may be provided on a lid body (not shown) of the container 21, an outer wall communicating with the inside of the container 21, or an inner wall of the container 21.

[0046] FIG. 8 is a flowchart illustrating a deodorizing method performed by the deodorizing device of the third embodiment. The flowchart shown in FIG. 8 compares the pressure measured by the pressure gauge 73 with a predetermined atmospheric pressure or the air pressure in the space F measured by a barometer (not shown). As shown in FIG. 8, the intake control unit 30 determines whether the pressure detection signal Sf is higher than the threshold value Pth1 and lower than the threshold value Pth2 (step S801). In step S801, if the pressure indicated by the pressure detection signal Sf is higher than the threshold value Pth1 and lower than the threshold value Pth2 (step S801: YES), the intake control unit 30 controls the amount of power supplied to the deodorizing fan 31 so as to maintain the intake air volume (step S806). Next, the intake control unit 30 determines whether the pressure indicated by the pressure detection signal Sf is lower than the threshold value Pth1 (step S802). In step S802, if the pressure indicated by the pressure detection signal Sf is smaller than the threshold value Pth1 (step S802: YES), the intake control unit 30 reduces the amount of power supplied to the deodorizing fan 31 so as to reduce the amount of intake air (step S807).

[0047] In step S802, if the pressure indicated by the pressure detection signal Sf is not less than threshold value Pth1 (step S802: NO), the intake control unit 30 determines whether the pressure indicated by the pressure detection signal Sf is higher than threshold value Pth2 (step S803). Threshold value Pth2 is a threshold at which the air pressure inside container 21 is equal to or higher than the air pressure in space F, i.e., a threshold at which a flow of gas from container 21 to space F can be detected. If the pressure indicated by the pressure detection signal Sf is higher than threshold value Pth2 (step S803: YES), the intake control unit 30 increases the amount of power supplied to deodorizing fan 31 so as to increase the amount of intake air (step S808).

[0048] Furthermore, the intake control unit 30 determines whether the pressure detection signal Sf is an error signal (step S804). If the pressure detection signal Sf is an error signal in step S804 (step S804: YES), the intake control unit 30 increases the amount of power supplied to the deodorizing fan 31 so as to increase the amount of intake air (step S808). The determination in step S804 takes into consideration the case where the container 21 is not sufficiently airtight and the pressure measurement is inaccurate. In the third embodiment, if the pressure measurement value is not sufficiently reliable, the intake amount is increased to prevent odor leakage from the container 21. In addition, in the third embodiment, if the pressure detection signal Sf is an error signal, an alarm indicating that an error signal has been detected may be output to the outside.

[0049] In the third embodiment, the pressure detection signal Sf is detected at regular time intervals. Therefore, the intake control unit 30 determines whether the next detection time has arrived (step S804). The intake control unit 30 waits until the detection time (step S804: NO), and when the detection time arrives (step S804: YES), the process returns to step S801 and inputs the pressure detection signal Sf. However, the detection of the pressure detection signal Sf is not limited to being performed at regular time intervals, and may be performed continuously.

[0050] In the third embodiment, the intake control unit 30 may input a plurality of pressure detection signals Sf and increase the intake volume of the deodorizing fan 31 until odor leakage is no longer detected in all of the containers 21. Furthermore, in the third embodiment, instead of controlling the wind speed of each individual container, the intake volume of one deodorizing fan may be controlled for a group of multiple containers 21. Also, in the third embodiment, weights may be assigned to the multiple containers 21, and priority may be given to the value indicated by the pressure detection signal Sf corresponding to the container 21 with the heaviest weight.

[0051] The odor prevention system, odor prevention device, and odor prevention method of the present embodiment described above control the amount of intake air by increasing or decreasing the amount of power supplied to the deodorizing fan 31 depending on the state of odor leakage. As a result, this embodiment can reduce the costs associated with odor prevention. Furthermore, the first and second embodiments can detect the possibility of odor leaking from the container 21 to the outside by measuring the gas flow between the container 21 and the outside. The third embodiment can detect the possibility of odor leaking from the container 21 to the outside by measuring the pressure inside the container 21. Even when an odor is present in the environment, this embodiment can determine whether the odor is caused by sewage treatment or some other cause. [Explanation of symbols]

[0052] 1 Environment 5 Sewage manhole 6. Sewage manhole 7, 8 Sewer pipe 9. Settling pond 10 Primary sedimentation tank 11 Aeration tank 12 Final sedimentation tank 13 Chlorine mixing pond 21 Container 23 Wind vane 25 Pipe 27 Damper 29 Duct 30 Intake control section 31 Deodorizing fan 53 Anemometer 73 Pressure Gauge

Claims

1. a container for containing the water to be treated; an intake fan that draws in gas from inside the container; a gas state detection unit that detects gas information indicating the state of gas inside the container; an intake control unit that changes the intake amount of the intake fan based on the gas information, Odor prevention system.

2. a gas state detection unit that detects gas information indicating the state of gas inside a container that contains the water to be treated; an intake control unit that changes an intake amount of an intake fan that draws in gas inside the container based on the gas information, Odor control device.

3. The deodorization device according to claim 2 , wherein the gas state detection unit is a wind vane that detects the direction of gas flowing between the container and the outside of the container.

4. 3. The deodorization device according to claim 2, wherein the gas state detection unit is an anemometer that detects the speed of gas flowing between the container and the outside of the container.

5. The deodorization device according to claim 2 , wherein the gas state detection unit is a pressure gauge that detects the pressure inside the container.

6. The odor deodorization device according to claim 2 , wherein the intake control unit controls an opening degree of a damper between the container and the intake fan based on the gas information.

7. detecting gas information indicating a state of gas inside a container that contains the water to be treated; and changing the intake amount of an intake fan that draws in the gas inside the container based on the gas information. Odor prevention method.

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