Decarbonization-type purification tank

Abstract

[Problem] To provide a purification treatment tank, that is, a decarbonization-type purification tank, that can wash a filtration carrier through new energy consumption rather than conventional consumption of electric power. [Solution] A decarbonization-type purification tank 1 comprises: a plurality of treatment tanks 2-4 including at least one anaerobic treatment tank; and a washing device 5 for washing filtration carriers 6a, 6b in the anaerobic treatment tank. The washing device 5 comprises: a gas reservoir 7 that can store gases Ga, Gb; a gas collection section 8 that is connected to the gas reservoir 7 and collects, at an upper part thereof, the gas Ga generated in at least one treatment tank 3 among the plurality of treatment tanks 2-4; an outside air supply device 9 that is driven by photovoltaic power generation 10 and supplies outside air Gb as gas to the gas reservoir 7; and an air lift pump 11 that is driven by the gases Ga, Gb stored in the gas reservoir 7 and is configured to be capable of returning a treatment water W inside the treatment tank 4, which is positioned at the downstream side among the plurality of treatment tanks 2-4, to the treatment tank 2 positioned at the upstream side.

Description

Decarbonized septic tank

[0001] The present invention relates to a purification treatment device, i.e., a decarbonized septic tank, that can be driven for purification treatment using driving energy that does not emit greenhouse gases like fossil fuels.

[0002] Conventionally, in septic tanks that purify wastewater and other wastewater through biological filtration, the front section (upstream) is filled with relatively large filter media for anaerobic treatment, while the rear section (downstream) is filled with relatively small filter media for aerobic treatment, with air supplied from an external fan.

[0003] Also, as this type of septic tank, there is known a septic tank that is equipped with a cleaning device (hereinafter simply referred to as "cleaning device") that uses air supplied from a blower to instantly lower the water level in the treatment tank in which the filter carrier is housed, thereby cleaning the filter carrier and the like (see Patent Documents 1 to 4, etc.).

[0004] Such a cleaning device comprises an air supply pipe connected to a blower, an air reservoir chamber that is submerged in the treatment tank and stores the air sent from the air supply pipe, and an exhaust pipe that is inserted into the air reservoir chamber and discharges the stored air out of the treatment tank when a predetermined amount of air has been stored in the air reservoir chamber.When the stored air in the air reservoir chamber is discharged from the exhaust pipe, the water in the treatment tank flows into the air reservoir chamber, instantly lowering the water level in the treatment tank and cleaning the filter carrier in the treatment tank.

[0005] Japanese Patent Application Laid-Open No. 8-132082 Japanese Patent Application Laid-Open No. 2010-184210 Japanese Patent Application Laid-Open No. 2010-207662 Japanese Patent Application Laid-Open No. 2021-10876

[0006] For example, it is estimated that there are approximately 7.5 million septic tanks installed and operational in Japan (as of 2019). The fans attached to each septic tank are powered by electricity provided by various power generation facilities. Assuming each fan operates 24 hours a day with an average power output of 50W (0.05kW), this amounts to approximately 400,000kW of electricity, equivalent to the power consumed by a single nuclear power plant. Given the recent acceleration of efforts toward decarbonization, there is a need for decarbonization-oriented efforts (improvements) for septic tanks, which consume a great deal of energy.

[0007] Therefore, the problem to be solved by the present invention is to provide a septic tank that can clean the filter carrier using new energy consumption instead of conventional electricity consumption, i.e., a decarbonized septic tank.

[0008] The above problems are solved by the decarbonization type septic tank according to the present invention. In other words, this septic tank comprises a plurality of treatment tanks, including at least one anaerobic treatment tank in which a filter carrier is housed, and a cleaning device for cleaning the filter carrier in the anaerobic treatment tank. The cleaning device comprises a gas reservoir capable of storing gas, a gas collection unit connected to the gas reservoir and collecting gas generated in at least one of the plurality of treatment tanks at its upper portion, an outside air supply unit powered by electricity generated using renewable energy and supplying outside air as gas to the gas reservoir directly or indirectly, and an air lift pump powered by the gas stored in the gas reservoir and configured to return treated water from a downstream treatment tank of the plurality of treatment tanks to an upstream treatment tank. When the gas stored in the gas reservoir reaches a predetermined amount and the pressure balance between the stored gas and the treated water is disrupted, the air lift pump is activated to generate a flow of treated water in the anaerobic treatment tank as the water level rises in the gas reservoir, thereby cleaning the filter carrier.

[0009] As described above, the septic tank of the present invention includes a gas collection section that collects gas generated in each treatment tank and is connected to the gas reservoir. It also includes an outside air supply device that is powered by electricity generated using renewable energy and supplies outside air as gas to the gas reservoir. This allows the air lift pump to be operated using only natural energy, without using any fossil fuel-derived electrical energy, as is required for conventional blowers. Furthermore, by providing both the gas collection section and the outside air supply device, even when the amount of gas generated in each treatment tank is small, a sufficient amount of gas to operate the air lift pump can be supplied to the gas reservoir at a constant interval. As described above, the present invention contributes to the suppression of greenhouse gases such as carbon dioxide while providing stable, excellent cleaning results.

[0010] As described above, with the decarbonized septic tank of the present invention, the filter carrier can be cleaned using only natural energy instead of conventional electric energy, which not only contributes to decarbonization but also makes it possible to ensure the purification capacity of the septic tank over the long term due to the stable cleaning effect of the filter carrier.

[0011] FIG. 1 is a cross-sectional view of a decarbonization septic tank according to one embodiment of the present invention. FIG. 2 is a plan view of the decarbonization septic tank shown in FIG. 1. FIG. 3 is a view showing an example of use of the decarbonization septic tank shown in FIG. 1, showing a state where gas has begun to accumulate in a gas reservoir. FIG. 4 is a view showing an example of use of the decarbonization septic tank shown in FIG. 1, showing a state where gas has begun to flow into an air lift pump. FIG. 5 is a view showing an example of use of the decarbonization septic tank shown in FIG. 1, showing a state where gas has progressed in flow into the air lift pump. FIG. 6 is a view showing an example of use of the decarbonization septic tank shown in FIG. 1, showing a state where the balance between the gas pressure and the pressure of the treated water in the air lift pump has been lost. FIG. 7 is a view showing an example of use of the decarbonization septic tank shown in FIG. 1, showing a state where lift-up of the treated water has occurred by the air lift pump. FIG. 8 is a cross-sectional view of a decarbonization septic tank according to another embodiment of the present invention. FIG. 9 is a cross-sectional view of a decarbonization septic tank according to another embodiment of the present invention.

[0012] Hereinafter, the details of a decarbonization type septic tank according to one embodiment of the present invention will be described with reference to the drawings.

[0013] 1 shows a cross-sectional view of a decarbonization type septic tank 1 according to one embodiment of the present invention. The septic tank 1 mainly comprises a plurality of treatment tanks 2 to 4 and a cleaning device 5.

[0014] The cleaning device 5 also includes a gas reservoir 7 , a gas collection unit 8 , an outside air supply device 9 , a solar power generation device 10 , and an air lift pump 11 .

[0015] The multiple treatment tanks 2-4 each include at least one anaerobic treatment tank. In this embodiment, all three treatment tanks 2-4 can function as anaerobic treatment tanks. The first treatment tank 2, located most upstream among the three treatment tanks 2-4, is partitioned by a partition wall 13 into a first chamber 2a located relatively upstream and a second chamber 2b located relatively downstream. In this case, an inlet 14 for the treated water W is provided at the top of the first chamber 2a. Multiple filter media 6a are housed in a predetermined area of ​​the second chamber 2b, and the vertical movement of the filter media 6b is restricted within a predetermined range by upper and lower restricting members 15a, 15b. The restricting members 15a, 15b may be made of wire mesh, plastic mesh, or the like that does not allow the filter media 6b to pass through. Anaerobic microorganisms are attached to each filter media 6a, and the treated water W passing through the filter media 6a (the second chamber 2b of the first treatment tank 2) is subjected to decomposition treatment utilizing the metabolic reactions of the anaerobic microorganisms.

[0016] The second treatment tank 3 is disposed downstream of the first treatment tank 2. The second treatment tank 3 is divided by a partition wall 16 into a first chamber 3a on the relatively upstream side and a second chamber 3b on the relatively downstream side. A plurality of filter media 6a are housed in a predetermined area of ​​the first chamber 3a, and the vertical movement of the filter media 6b is restricted within a predetermined range by upper and lower restricting members 15a, 15b. As in the first treatment tank 2, anaerobic microorganisms are attached to each filter media 6a in the second treatment tank 3, and the treated water W passing through the filter media 6a (first chamber 3a of the second treatment tank 3) is subjected to decomposition treatment utilizing the metabolic reactions of the anaerobic microorganisms.

[0017] The third treatment tank 4 is disposed downstream of the second treatment tank 3. A plurality of filter media 6b are housed in a predetermined area of ​​the third treatment tank 4, and the vertical movement of the filter media 6b is restricted within a predetermined range by upper and lower restricting portions 16a, 16b. Here, the relatively large filter media 6a are disposed in the upstream treatment tanks (the first treatment tank 2 and the second treatment tank 3), and the relatively small filter media 6b are disposed in the downstream treatment tank (the third treatment tank 4). The restricting portions 16a, 16b may be made of a wire mesh, plastic mesh, or the like that does not allow the filter media 6b to pass through.

[0018] In this case, the treated water W that flows into the first chamber 2a of the first treatment tank 2 from the inlet 14 flows from below the first chamber 2a into the second chamber 2b, passes from bottom to top through the storage area of ​​the filter carrier 6a, and then flows from above the second chamber 2b into the second treatment tank 3. The treated water W that flows into the second treatment tank 3 passes from top to bottom through the storage area of ​​the filter carrier 6a provided in the first chamber 3a, flows into the adjacent second chamber 3b, passes from bottom to top through the second chamber 3b, and flows from above into the third treatment tank 4. The treated water W that flows into the third treatment tank 4 passes from top to bottom through the storage area of ​​the filter carrier 6b provided in the third treatment tank 4, and then is released out of the decarbonization type septic tank 1 through the outlet 17 provided further downstream.

[0019] The cleaning device 5 will now be described in detail.

[0020] The gas reservoir 7 is, for example, substantially box-shaped and has a downward opening, which allows it to store a predetermined gas. In this embodiment, the gas reservoir 7 is disposed inside the third treatment tank 4 and is located at a position lower than the water surface of the treated water W in the third treatment tank 4. Therefore, when no gases Ga and Gb (described later) are stored in the gas reservoir 7, the entire gas reservoir 7 is submerged in the treated water W (see FIG. 1).

[0021] The gas collection unit 8 is configured to collect, at its upper portion, gas Ga generated in at least one of the treatment tanks 2 to 4, and is connected to the gas reservoir 7 via a flow pipe 18. This allows the gas Ga collected by the gas collection unit 8 to be sent to the gas reservoir 7 and stored therein. In this embodiment, the gas collection unit 8 is shaped so that it opens downward and the opening area increases as it extends downward. The gas collection unit 8 configured as described above is disposed above the accommodation area of ​​the filter carrier 6a in the first chamber 3a of the second treatment tank 3. This allows the collection of gas Ga, which is an organic gas generated during the process of microbial decomposition of organic wastewater in the accommodation area of ​​the filter carrier 6a or in sediments S such as sludge accumulated at the bottom of each treatment tank 2 to 4.

[0022] The outside air supply device 9 is capable of supplying outside air Gb as gas to the gas reservoir 7 and is capable of being driven by power generated by the solar power generation device 10. Any gas supply device can be used as the outside air supply device 9, and a blower is preferably used, for example. In this embodiment, an outside air supply pipe 24 is connected to the outside air supply device 9, and the tip opening of the outside air supply pipe 24 is disposed below the gas reservoir 7, so that the outside air Gb pressurized by the outside air supply device 9 is directly supplied to the gas reservoir 7 through the outside air supply pipe 24.

[0023] As described above, the outside air Gb may be supplied directly or indirectly to the gas reservoir 7. That is, when the gas reservoir 7 is connected to the gas collecting unit 8 via the communicating pipe 18 as in this embodiment, the outside air supply device 9 and the outside air supply pipe 24 may be configured so that the outside air Gb is supplied to the gas collecting unit 8 or the inside of the communicating pipe 18.

[0024] The air lift pump 11 integrally includes a first flow pipe 19, a second flow pipe 20, and a communication pipe 21 that connects the lower end of the first flow pipe 19 and the lower end of the second flow pipe 20. In this configuration, the first flow pipe 19 and the second flow pipe 20 extend vertically, and the communication pipe 21 is connected to each other while extending horizontally. Note that "extending vertically" does not necessarily mean extending only vertically; some inclination relative to the horizontal is acceptable. Similarly, "extending horizontally" does not necessarily mean extending only horizontally; some inclination relative to the horizontal is acceptable. In the illustrated example, both flow pipes 19 and 20 extend linearly, but curved shapes are not completely excluded.

[0025] An opening 19a is provided in the first flow pipe 19 above the connection position with the communicating pipe 21, and this opening 19a is located within the gas reservoir 7. In this embodiment, the opening 19a is the upward-facing connection port of three connection ports of a tee (T-shaped joint) 19b connected to the first flow pipe 19. The first flow pipe 19 is connected to the side-facing connection port of the tee 19b. A return pipe 22 is connected to the end (upper end) of the second flow pipe 20 opposite the communicating pipe 21. The return pipe 22 extends to a treatment tank (here, the first treatment tank 2) located upstream of a treatment tank (here, the third treatment tank 4) in which the air lift pump 11 is installed.

[0026] An intake pipe 23 for the treated water W is connected to the first circulation pipe 19. In this embodiment, the intake pipe 23 is connected to a connection port facing downward of the tee 19b. In this case, the intake pipe 23 extends vertically, and can draw the treated water W near the bottom of the third treatment tank 4 by the action of an air lift pump 11, which will be described later.

[0027] Next, an example of use of the decarbonization type septic tank 1 having the above configuration will be described mainly with reference to FIGS.

[0028] First, in the initial stage after the treatment water W is introduced, as shown in Figure 1, the entire gas reservoir 7 and gas collection section 8 are both submerged in the treatment water W in each of the treatment tanks 3 and 4. In this case, the first circulation pipe 19, the second circulation pipe 20, and the communication pipe 21 that constitute the air lift pump 11 are also filled with the treatment water W.

[0029] When the treated water W flows into the first treatment tank 2 through the inlet 14, the treatment water W undergoes the purification process (anaerobic treatment in this case) described above in each of the treatment tanks 2 to 4. Referring to FIG. 3 , the gas Ga generated in the first chamber 3a of the second treatment tank 3 is collected by the gas collector 8 located above the filter carrier 6a and sent to the gas reservoir 7 through the connecting pipe 18. As a result, at least the gas Ga generated in the second treatment tank 3 is stored in the gas reservoir 7. Furthermore, when the weather conditions allow the solar power generation device 10 to operate, the outside air supply device 9 is driven by the power generated by the solar power generation device 10, and outside air Gb is supplied as gas to the gas reservoir 7 through the outside air supply pipe 24 (see FIG. 3 ).

[0030] As the gas accumulates in the gas reservoir 7 as described above, the position of the gas-liquid interface (the surface of the treated water W) in the gas reservoir 7 is gradually pushed down. Then, the treated water W is pushed down to the opening 19a of the first flow pipe 19, which serves as the gas inlet of the air lift pump 11, causing gases Ga and Gb to flow into the first flow pipe 19, and the gas-liquid interface in the first flow pipe 19 is pushed down (see FIGS. 4 and 5).

[0031] Then, as the supply of gases Ga and Gb to the gas reservoir 7 continues, when the amount of gases Ga and Gb stored in the gas reservoir 7 reaches a predetermined amount, in other words, when the balance between the pressure of the gases Ga and Gb in the air lift pump 11 and the pressure of the treated water W is lost (for example, as shown in FIG. 6 ), the gases Ga and Gb in the air lift pump 11 are discharged to the outside of the air lift pump 11 through the return pipe 22. Accompanying this discharge phenomenon, the treated water W located below the gas reservoir 7 in the third treatment tank 4 rises instantaneously, and the treated water W immediately below the accommodation area of ​​the filter media 6b connected to the bottom of the gas reservoir 7 is drawn downward instantaneously (see FIG. 7 for both). This results in the cleaning treatment of the filter media 6b in the third treatment tank 4.

[0032] Furthermore, with the flow of the gases Ga and Gb described above, the gas Ga in the gas collecting section 8, which is in communication with the gas reservoir 7, is discharged to the outside of the air lift pump 11 via the communicating pipe 18, the gas reservoir 7, and the return pipe 22. This discharge phenomenon causes the treated water W located directly below the gas collecting section 8 to instantaneously flow upward. This causes the filter carrier 6a in the second treatment tank 3 to be cleaned.

[0033] Furthermore, in this embodiment, the lower opening of the inlet pipe 23 for the treated water W is located near the bottom of the third treatment tank 4, so that, in conjunction with the flow action of the gases Ga and Gb described above, the treated water W near the bottom of the third treatment tank 4 is pulled up through the lower opening of the inlet pipe 23, and the sediment S deposited on the bottom is also pulled up and returned together with the treated water W to the first treatment tank 2. This reduces the amount of sediment S downstream. Furthermore, the amount of sediment S also decreases when the sediment S returned to the upstream treatment tank (here, the first treatment tank 2) is subjected to purification treatment together with the treated water W in each of the treatment tanks 2 to 4.

[0034] As described above, the decarbonization septic tank 1 according to this embodiment includes a gas collection unit 8 that collects gas Ga generated in the second treatment tank 3 and is connected to the gas reservoir 7. The outside air supply unit 9 is also provided, driven by a solar power generation device 10, and supplies outside air Gb to the gas reservoir 7 as gas. Therefore, unlike conventional blowers, the air lift pump 11 can be operated using only natural energy, without using any electrical energy generated using fossil fuels. Furthermore, by providing both the gas collection unit 8 and the outside air supply unit 9, even when the amount of gas Ga generated in the second treatment tank 3 is small, a sufficient amount of gas Gb to operate the air lift pump 11 can be supplied to the gas reservoir 7 over a certain period of time. As described above, the decarbonization septic tank 1 according to this embodiment can stably provide excellent cleaning effects while contributing to the suppression of greenhouse gases such as carbon dioxide.

[0035] Although one embodiment of the present invention has been described above, the decarbonization type septic tank according to the present invention can have other configurations as long as they do not deviate from the spirit of the invention. In the above embodiment, a solar power generation device 10 is used as an example, but the present invention is not limited to solar power generation as long as it generates electricity using renewable energy. For example, a power generation device using other renewable energy that does not generate carbon dioxide, such as wind power, geothermal power, hydropower, biomass, etc., may also be used.

[0036] For example, in the above embodiment, the opening 19a of the first flow pipe 19, which serves as the gas inlet of the air lift pump 11, is disposed within the gas reservoir 7, but this is of course not limiting. For example, although not shown, the opening 19a of the first flow pipe 19 may be directly connected to the communicating pipe 18 so that the gas Ga collected in the gas collecting unit 8 flows into the first flow pipe 19. In this case, the gas reservoir 7 is composed of the first flow pipe 19 and the communicating pipe 18. Furthermore, although not shown, an outside air supply pipe 24 may be connected to the communicating pipe 18 or the first flow pipe 19 so that outside air Gb can be directly sent into the first flow pipe 19. In any case, the air lift pump 11 and the gas reservoir 7 can be configured as desired, as long as they can be cleaned by operating the air lift pump 11 when the gas Ga, Gb stored in the gas reservoir 7 reaches a predetermined amount and the pressure balance between the stored gas Ga, Gb and the treated water W is disrupted, thereby generating a flow of treated water W in the anaerobic treatment tank as the water level in the gas reservoir 7 rises.

[0037] In the above embodiment, the gas collection unit 8 is disposed only above the filter carrier 6a in the second treatment tank 3, but other configurations are of course possible. For example, although not shown, the gas collection unit 8 may be disposed above the filter carriers 6a and 6b housed inside two or more of the treatment tanks 2 to 4, and the gas Ga generated in the filter carrier 6a and 6b housing area of ​​each of the treatment tanks 2 to 4 may be collected and sent to the gas reservoir 7.

[0038] Of course, even if the treatment tank is not an anaerobic treatment tank, if sediment S accumulates at the bottom due to various purification processes, gas Ga may be generated from the accumulated sediment S, so the gas collection section 8 may be installed in a treatment tank other than an anaerobic treatment tank.

[0039] In the above explanation, an example was given in which three treatment tanks 2 to 4 were provided in the decarbonization type septic tank 1, but of course two or four or more treatment tanks may be provided. Furthermore, one or more of these treatment tanks may be treatment tanks other than anaerobic treatment tanks. Furthermore, the direction in which treated water flows in each of the multiple treatment tanks may be configured to be different from that shown in the illustration.

[0040] Furthermore, the air lift pump 11 is not limited to the above embodiment. For example, as shown in FIG. 8, a lead-in pipe 23 can be connected to the second flow pipe 20, or as shown in FIG. 9, the lead-in pipe 23 can be formed by extending the lower part of the second flow pipe 20.

[0041] REFERENCE SIGNS LIST 1 Decarbonization type septic tank 2 First treatment tank 3 Second treatment tank 4 Third treatment tank 5 Cleaning device 6a, 6b Filter carrier 7 Gas accumulation section 8 Gas collection section 9 Outside air supply device 10 Solar power generation device 11 Air lift pump 13, 16 Partition wall 14 Inlet 15a, 15b, 16a, 16b Regulating section 17 Discharge port 18 Connecting pipe 19 First circulation pipe 19a Opening 20 Second circulation pipe 21 Connecting pipe 22 Return pipe 23 Intake pipe 24 Outside air supply pipe Ga Gas Gb Outside air S Sediment W Treated water

Claims

1. A decarbonized septic tank comprising: a plurality of treatment tanks including at least one anaerobic treatment tank in which a filtration carrier is housed; and a cleaning device for cleaning the filtration carrier in the anaerobic treatment tank, wherein the cleaning device comprises: a gas reservoir portion capable of storing gas; a gas collection portion connected to the gas reservoir portion and collecting gas generated in at least one of the plurality of treatment tanks at an upper portion thereof; an outside air supply device driven by electricity generated using renewable energy and supplying outside air as gas to the gas reservoir portion; and an air lift pump driven by the gas stored in the gas reservoir portion and configured to return treated water inside a treatment tank located downstream of the plurality of treatment tanks to a treatment tank located upstream, wherein when the gas stored in the gas reservoir portion reaches a predetermined amount and the pressure balance between the stored gas and the treated water is lost, the air lift pump is operated to generate a flow of the treated water in the anaerobic treatment tank associated with a rise in the water level in the gas reservoir portion, thereby making it possible to clean the filtration carrier.

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