Aeration structure utilizing negative pressure in wastewater
The aeration structure harnesses wastewater flow to generate compressed air for sewer systems, addressing high power and maintenance costs, ensuring continuous operation, and improving reliability by using a negative pressure-based system.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Utility models
- Current Assignee / Owner
- 吉田 眞纪
- Filing Date
- 2026-03-18
- Publication Date
- 2026-07-17
Smart Images
Figure 0003256661000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to an aeration structure using compressed air generated by a falling water blower that utilizes the negative pressure when draining water falls in a building or an upstream part of a depression.
Background Art
[0002] In the downstream part of a depression or the stagnant part of a pressure - feeding sewer pipe, the flow velocity decreases, and an environment where oxygen is difficult to be supplied is formed. In such an anaerobic environment, anaerobic bacteria such as sulfate - reducing bacteria are activated, and sulfates in sewage are reduced to generate hydrogen sulfide (H2S). Hydrogen sulfide has strong corrosiveness and toxicity, and is known as one of the most serious deterioration factors in sewer facilities. Particularly in concrete structures, hydrogen sulfide reacts with moisture to generate sulfuric acid, and "sulfuric acid corrosion" that dissolves calcium components in concrete progresses. As the corrosion progresses, the concrete surface softens and peels off, the reinforcing bars are exposed, and the corrosion accelerates. Eventually, the strength of the pipe wall is significantly reduced, and there is a risk of the pipeline collapsing. When the pipeline collapses, the surrounding earth and sand flow in from the damaged part, and a cavity, so - called "cavitation", is formed above the pipe. When this cavity expands, the supporting force of the ground surface is lost, and it develops into a road subsidence accident. Actually, many road subsidence accidents caused by the corrosion and damage of sewer pipes have been reported both at home and abroad, which has become a major problem related to the safety of social infrastructure.
[0003] In order to suppress the generation of hydrogen sulfide, conventionally, a compressor has been installed, and a method of injecting compressed air into the sewage stagnant part to eliminate the anaerobic environment, so - called aeration, has been widely adopted. This is because by supplying air, the amount of dissolved oxygen can be increased, the activities of anaerobic bacteria can be suppressed, and the generation of hydrogen sulfide can be prevented.
[0004] Furthermore, methods using compressed air have been proposed for removing settling contaminants in inverted siphon structures. For example, see Patent Document 1. The technology described in that publication employs a configuration in which multiple air discharge holes are provided in the vent pipe, and compressed air is supplied by a compressor for a predetermined time to lift the contaminants and remove them by flowing them down. However, this method has the problem that electricity is required to supply compressed air, which increases equipment costs and operating costs. In addition, if the frequency of compressed air supply is high, electricity consumption will increase, leading to increased maintenance costs.
[0005] Similarly, to remove stagnant water and sediment in inverted siphon pipelines, there is a method, as disclosed in Patent Document 2, that involves installing a circulation pump in a portion of the transverse pipe to forcibly create a backflow from the downstream side to the upstream side. The technology in the same publication shows a configuration in which wastewater is circulated and flowed by operating a circulation pump or airlift pump to suppress the accumulation of scum and sludge. However, all of these methods require power equipment using electricity and have reliability problems as they stop functioning during power outages. In addition, if the depth of the inverted siphon is large, the pump head increases, which presents the challenge of high equipment and power costs.
[0006] Furthermore, Patent Document 3 discloses a configuration in which a sludge discharge pipe is provided at the outlet of the lateral flow section, and compressed air is supplied into the sludge discharge pipe from a compressed air supply device as needed to forcibly scoop up and discharge sediment and other materials. This publication assumes that the sediment inside the inverted siphon structure is forcibly removed using a compressor or the like or a pressurized water supply device, which leads to the same power consumption problems as in paragraph 0005.
[0007] In the United States, devices for supplying air to aeration tanks and grit chambers have been proposed as aeration technologies for sewage treatment plants (e.g., US5462657A, US6921489B2, US4288394A). However, these all target aeration within treatment plants, and no aeration technologies aimed at preventing the accumulation of foreign matter in sewer pipes or inverted siphon structures have been disclosed. Furthermore, these technologies are based on power equipment such as compressors, and no structures that utilize the negative pressure of wastewater to perform aeration by natural intake have been found. [Prior art documents] [Patent Documents]
[0008] [Patent Document 1] Patent No. 7541463 [Patent Document 2] Japanese Patent Publication No. 2004-251038 [Patent Document 3] Patent No. 5695495 [Non-patent literature]
[0009] [Non-Patent Document 1] "Sewer Pipes: Reducing Costs Through Elegant Design" by Fujiro Narihara, Sankaido, 2005. [Overview of the project] [Problems that the invention aims to solve]
[0010] The background technologies described above have the following challenges. High power consumption: Compressors require long operating times, resulting in continuous electricity costs. Equipment maintenance is essential: Compressors require regular inspections, parts replacement, and lubrication management, which incur costs for outsourcing to specialized companies. The financial burden on local governments is increasing: Since public sewage systems are managed by local governments, all equipment costs, operating costs, and maintenance costs are borne by the local government, which ultimately leads to a burden on the residents. Does not function during power outages: During disasters or power outages, the aeration function stops, posing a risk of rapid accumulation of hydrogen sulfide.
[0011] While conventional compressed air systems have some effectiveness, they suffer from structural challenges such as dependence on electricity, maintenance burden, and vulnerability during power outages. Therefore, there is a need for a system that uses only the energy of wastewater flow to perform aeration without using electricity. [Means for solving the problem]
[0012] (1) The apparatus is characterized by comprising a negative pressure generating unit that draws in air using the negative pressure generated by the flow or movement of wastewater, and a mixing unit that mixes air into the wastewater, and further comprising a separation chamber that separates the air and wastewater, and capable of generating compressed air for aeration of the wastewater.
[0013] (2) The negative pressure generating section is located in the middle of the building drainage system, Alternatively, a 45-degree cheese structure, Alternatively, the structure shown in Figure 5 By creating this configuration, air can be drawn in by the negative pressure caused by the falling drainage. Furthermore, instead of using the entire drainage from a single floor, it is possible to use drainage with fewer impurities by separately extracting the drainage from multiple bathtubs, as shown in Figure 2.
[0014] (3) The negative pressure generating unit can be configured to generate negative pressure by taking out a portion of the wastewater from the upstream section of the inverted siphon and letting it fall. If there is a lot of impurities in the wastewater from the upstream section of the inverted siphon, it is desirable to take out a water flow with less impurities using a swirl structure with a vortex flow as shown in Figure 4. [Effects of the Invention]
[0015] According to this invention, by separately supplying compressed air generated by drainage from multiple bathtubs in a high-rise building or by a water-dropping ventilation mechanism built upstream of the inverted siphon, aeration of the pressurized sewer pipeline and the sewer stagnant area downstream of the inverted siphon can be carried out without consuming electricity.
[0016] That is, according to the present invention, the air required for aeration is sucked by the flowing-down energy (negative pressure) of the wastewater, so power equipment such as a compressed air supply device and a pump becomes unnecessary. Therefore, the power consumption becomes zero, and the power cost and maintenance cost can be reduced. Also, since the aeration function is maintained even during a power outage, the reliability in an emergency is high. Furthermore, in the present invention, since there are no moving parts such as pumps, the maintenance cost can be reduced and the reliability is also high.
[0017] Note that the pressure fluctuation in the drain pipe is generally handled for the purpose of ensuring the ventilation performance, and the idea of actively using the negative pressure to generate compressed air has not been studied in the field of building drainage and sewer technology. Therefore, the present structure that combines the negative pressure due to the falling water and the separation chamber to obtain the aeration air has a feature that it cannot be easily derived from the conventional design concept.
[0018] Furthermore, in the present invention that uses domestic wastewater, since the generation of wastewater is linked to daily activities, the aeration amount naturally follows the time-of-day variation. That is, during the bathing time in the morning and evening, the amount of wastewater discharged increases, and accordingly, the amount of negative pressure generated and the amount of air sucked also increase, so the aeration amount automatically becomes stronger. On the other hand, during the time period with less wastewater discharge such as late at night, the required aeration amount also naturally decreases to achieve a reasonable operating state.
[0019] In this way, there is novelty in that "autonomous aeration control" according to the amount of wastewater discharge is realized without the need for a control device using electricity. Furthermore, the present invention is a novel combined structure of a falling water blower mechanism and wastewater such as a bathtub in a high-rise building.
Brief Description of the Drawings
[0020] [Figure 1] (1a) is a schematic diagram of creating compressed air in an aeration device according to an embodiment of the present invention. (1b) is a schematic diagram of injecting the compressed air created in (1a) into a pressure feed pipe or a downstream part over a ridge through a check valve. [Figure 2] A diagram showing an outline of an aeration device using wastewater from a plurality of bathtubs on a certain floor of a building. [Figure 3]This diagram shows a model experiment of air suction observed using a transparent PVC pipe. [Figure 4] (4a) is a schematic diagram showing a mechanism for separating contaminants to some extent by providing a swirl in the upstream part of an inverted siphon according to one embodiment of the present invention, and a water blower. (4b) is an enlarged view of (4a) along the YY line. [Figure 5] A diagram illustrating one form of air intake when there is little impurity. [Modes for carrying out the invention] [Examples]
[0021] Next, Embodiment 1 of the present invention will be described with reference to the figures. This embodiment embodies the invention described in claim 2.
[0022] Figure 1a is a schematic diagram of a device that generates compressed air using the fall energy of drainage from a high-rise building according to the present invention. Drainage from the bathtub 1 generates negative pressure in the area of the 45-degree tee (different diameter 45-degree tee) 2, drawing in air. Negative pressure is generated if the amount of drainage is above a certain level, but to prepare for cases where this is not the case, it is desirable to set the upper end U of the air intake above the water level of the bathtub 1.
[0023] For drainage pipe 3, a thick-walled rigid polyvinyl chloride pipe (VP or HIVP) can be used if the length is 100 meters or less, but for lengths longer than that, a ductile cast iron pipe is preferable for safety reasons.
[0024] The air drawn in by the negative pressure is compressed as it moves towards the bottom of the pipe 3, mostly as air bubbles 5. Figure 3 shows a photograph of this process in a model experiment. This is called a trompe, and it is believed that a similar mechanism existed in the past to create compressed air for pumping water (air-lift pump) into the Alcazaba (fortress) in a section of the Alhambra Palace. This embodiment is a novel combination of this trompe and drainage from bathtubs in high-rise buildings.
[0025] The air bubbles that have reached the bottom of the drain pipe 3 are separated from the wastewater by the separation chamber 4. This allows for the creation of compressed air for aeration, as shown in Figure 1a. The pressure P (MPa: megapascals) of the compressed air is roughly determined by the length L (m: meters) of the drain pipe 3, and if losses are ignored, it is P = L / 100, but when losses are considered, it is roughly 70-80% of this pressure. The created compressed air is connected via a separate pipe, through a check valve, to a point that serves as the starting point for aeration, such as the upstream part of the pressurized sewer pipeline or the downstream part of the inverted siphon, as shown in Figure 1b.
[0026] For supplying compressed air, an air fiber tubing with a pressure resistance of 1.47 MPa can be used. If the pressure exceeds this, it is advisable to reduce the pressure using a pressure reducing valve before supplying the air.
[0027] The wastewater, separated from the air, proceeds to point T in Figure 1a. However, to create more stable compressed air, it is better to raise point T slightly using a 45-degree elbow or similar. In the case of wastewater from a bathtub, it is assumed that there will be fewer impurities, so it is possible to raise the level of the wastewater more significantly. However, in the case of general wastewater, it is desirable to limit the rise to a level that does not cause the formation of deposits such as scum.
[0028] Figure 2 is a schematic diagram showing a mechanism for creating compressed air using drainage from multiple bathtubs (three bathtubs in the diagram) on a floor of a building. Although the drainage from multiple bathtubs is combined into a pipe, the probability of draining the bathtubs (so-called "plugging") simultaneously is low, so in reality, it can be assumed that the mechanism is the same as that of draining from a single bathtub, i.e., the same as in Figure 1. From the 45-degree reducing tee 2 onwards, it is the same as in Figure 1.
[0029] In this embodiment, when sending compressed air obtained in the separation chamber 4 to the aeration air pipeline, the inner diameter and length of the air pipeline can be appropriately set to minimize pressure loss and stabilize the air discharge rate at the aeration point. In particular, since the bathtub drainage is relatively clear, the possibility of solid matter entering the air pipeline is extremely low, enabling a stable air supply over a long period of time. Furthermore, by using a configuration that connects via a check valve, backflow of water from the aeration point into the air pipeline can be reliably prevented, improving the reliability of the entire system.
[0030] It is considered best practice to increase the aeration airflow during times when more wastewater is being supplied and decrease it during other times. When aeration is performed using an electric compressor, a complex control mechanism is required to monitor the amount of wastewater and control the compressor airflow. However, with this invention, the aeration frequency follows the frequency of wastewater drainage from the bathtub, which has the advantage of essentially providing automatic control.
[0031] In this embodiment, when compressed air is created using drainage from a building's bathtub, it is desirable to extend the piping vertically from each floor to the extent necessary to obtain the desired compressed air pressure and to create separation chambers. The compressed air obtained from each separation chamber can be combined using a check valve / combination manifold (header pipe) or a pressure equalization tank (buffer tank). [Examples]
[0032] Next, Embodiment 2 of the present invention will be described with reference to the figures. This embodiment embodies the invention described in claim 3.
[0033] Figure 4 shows a structure in which a swirl 7 installed in the upstream part of the inverted siphon is used to separate some of the impurities in the sewage and obtain wastewater with fewer impurities for the water blower.
[0034] A swirl is a device that generates a vortex by introducing sewage tangentially along the inner wall of a cylindrical tank, and efficiently separates solid matter contained in sewage through an effect called the teacup effect (where solid matter is attracted to the center of the vortex due to the lift generated by the difference in angular velocity between the center and the outside of the vortex). This device is the structure depicted in Figure 4a, 7.
[0035] Due to the swirl, the main stream B of sewage with a lot of impurities is connected to the upstream part of the vent pipe inverted siphon (Non-Patent Literature 1), and the sewage with less impurities is connected to a 45-degree tee 2 with a different diameter, similar to that in Figure 1a. Compressed air is created by the same mechanism as in Figure 1 (Example 1), and is connected to the downstream part of the inverted siphon via the air pipeline and check valve.
[0036] Furthermore, when dealing with wastewater containing few impurities, air can be introduced using a simpler structure as shown in Figure 5, without using the swirl or the 45-degree tee 2 with different diameters.
[0037] In this embodiment, the wastewater from which impurities have been separated by the swirl 7 has a stable flow when supplied to the drop blower, improving the air suction efficiency in the negative pressure generation section. In particular, by dropping the wastewater with a small amount of solid matter, the amount of air reaching the separation chamber 4 does not fluctuate significantly over time. As a result, the supply of compressed air used for aeration is stabilized, and the aeration effect in the downstream section of the inverted siphon becomes more reliable.
[0038] Furthermore, the separation of solid matter by the swirl 7 also has the effect of preventing clogging and blockage of the flow path inside the fallwater blower. Various contaminants such as sand, gravel, scum, and fibrous materials are mixed in the upstream section of the inverted siphon, but in this embodiment, these are guided to the main flow side, so long-term maintenance-free operation is possible while keeping the structure of the fallwater blower simple.
[0039] In general tromps, it is desirable for air bubbles to be turbulent, and sometimes grid-like obstacles are intentionally placed in the middle of the pipe. However, in this invention, since wastewater containing some impurities is used, it is thought that a turbulent state will be achieved to some extent by the secondary effect of the impurities. Therefore, in order to prevent clogging by impurities, it is not appropriate to place obstacles in the middle of the drainpipe.
[0040] While the combination of separating impurities using swirl and generating negative pressure with a water-dropping blower is a known technology individually, the need to simultaneously satisfy the characteristics of solid matter in the sewage and the conditions for generating negative pressure, and the design concept of appropriately connecting the two to obtain stable compressed air, is not found in conventional technology.
[0041] This invention is not limited to the embodiments described above, and can be modified in various ways during implementation without departing from its essence. [Industrial applicability]
[0042] The negative pressure-based aeration structure described in this invention can be widely used in industry, not only for aeration in pressurized sewer pipelines or sewage stagnant areas downstream of inverted siphons, but also for aeration in sewage treatment flows. In fact, aeration alone accounts for approximately 30% to 60% of the total electricity consumption for sewage treatment.
[0043] <Points to note during implementation> Example 1 describes a case in which compressed air is created using drainage from multiple bathtubs in a high-rise building. While this requires separate piping for the bathtub drainage, resulting in additional design and construction costs, the aeration produced by the compressed air is in the public interest, making government subsidies desirable.
[0044] When supplying compressed air from private property such as a building to a public underground sewer pipeline or siphon, this constitutes a direct connection of private equipment to public infrastructure. Legally, four points are crucial: "occupancy," "connection permit," "backflow prevention," and "safety management responsibility." In practice, it is advisable to consult with the local government's sewerage administrator beforehand to clarify the connection location, pressure limit, emergency shutoff method, safety devices such as check valves, and the scope of maintenance responsibility, and then obtain an occupancy permit or connection approval. [Explanation of symbols]
[0045] 1... Bathtub 2. ... Reducing diameter 45-degree tee (reducing diameter 45-degree tee) 3. Thick-walled rigid polyvinyl chloride pipe or ductile cast iron pipe. 4... Separation room 5... Air bubbles 7... Swirl T... Separation chamber outlet (connection to the main sewer line) B... Connection to the vent pipe underpass F …… Drainage inflow part 41... Swirl exterior wall 42... Swirl inner wall
Claims
1. A negative pressure generating unit is installed in the middle of the drainpipe and generates negative pressure due to the falling of wastewater, An air mixing unit that communicates with the negative pressure generating unit and mixes air into the wastewater, It is equipped with a separation chamber that separates wastewater and air, An aeration structure that utilizes the fall energy of wastewater to obtain compressed air.
2. The aeration structure according to claim 1, wherein the compressed air production structure is configured by a negative pressure generating section provided in the middle of a building drainage pipe.
3. The aeration structure according to claim 1, wherein the compressed air production structure is configured by a negative pressure generating section provided in a part of the upstream section of the inverted siphon.