JPH11138192A - Device for dissolving oxygen into water in tank and method therefore - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device and a method enabling to surely dissolve oxygen into water in a sewage treating tank such as a grease trap, while the energy consumption is extremely restrained and the power cost is saved at minimum. SOLUTION: A water stream S mixed fine air bubbles Q is discharged from a static mixer 26 provided in the sewage 18 in the sewage treating tank 1 such as the grease trap and also in the vicinity of the water surface 11 of the sewage 18 so as to descend, while they gently and slowly spread in the sewage 18 in the grease trap 1, and also such that the fine air bubbles Q descend in accordance with the water steam S, and the oxygen is dissolved into the sewage 18 of the grease trap 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for dissolving oxygen in water in a tank, and more particularly, to an aerobic microorganism introduced into a sewage treatment tank such as a grease trap (oil interceptor). The present invention relates to an apparatus and a method suitable for dissolving oxygen into sewage of the tank in some cases.

[0002]

2. Description of the Related Art As a wastewater treatment facility for treating wastewater from a kitchen in a general company such as the food industry, a tank in which aerobic microorganisms are introduced into a grease trap is known. Is supplied with oxygen for sludge treatment by aerobic microorganisms.

[0003] In FIG. 6 showing an example of this type of conventional typical wastewater treatment equipment, reference numeral 101 denotes a sewage treatment tank such as a grease trap, and the sewage treatment tank 101 is composed of oil (lipid).
An inlet area 104 serving as an initial floating / separating tank by partitioning plates 102 and 103 for blocking floating substances such as and some other organic matter and floating sludge, and also serving as a floating / separating tank and a reaction tank or an aeration tank. It is partitioned into a processing area 105 and an outlet area 106 serving as a discharge tank. These three regions or chambers 104, 105, and 106 are communicated below the partition plates 102 and 103. Processing tank 1
The wastewater 107 to be treated is fed into the inlet area 104 of the tank 101 via a conduit 108, and solids released together with the wastewater 107 are supplied to the portion of the inlet area 104 where the wastewater 107 flows into the treatment area of the tank 101. A basket 104a is arranged to prevent entry into 105. In addition, aerobic microorganisms are also periodically injected into the entrance region 104. A diffuser 109 is provided at the bottom of the treatment area 105 of the sewage treatment tank 101, and air is sent from the blower 110 to the diffuser 109 via an air pipe 111. Power supply 11
Oxygen contained in the air blown into the processing area 105 of the processing tank 101 from the air diffuser 109 by driving the blower 110 supplied from 2 is dissolved in the water of the processing area 105, and flows in the direction A from the inlet area 104. Partition plate 10
2 is used for sludge treatment accompanying the survival and organic matter decomposition activity of the aerobic microorganisms that have entered the treatment area 105 through below. On the other hand, the water 113 in which oil (lipids) floats and separates, and in which organic substances are partially decomposed, is separated from the partition plate 1
It passes below B03 in the direction B into the exit area 106 and is further discharged via conduit 114. Reference numeral 118 denotes the ground.

However, in the conventional wastewater treatment equipment 100 as shown in FIG. 6, there is a limit to reducing the size of the hole of the diffuser 109 (200 to 500 microns). Bubbles 115 released into the sewage from the air diffuser 109 become large, so that the oxygen 115 in the bubbles hardly dissolves in the water, and it is difficult to increase the dissolved oxygen concentration in the water.
Therefore, in order to increase the dissolved oxygen concentration, it is necessary to blow a large amount of air bubbles 115, but most of the air bubbles 115 reach the surface of the water and escape, so that the power consumption which is originally expensive tends to increase ( Since this equipment is operated all day, the cost due to power consumption is not small. Further, by performing bubbling such that the air bubbles 115 reach the water surface, the water surface is greatly waved, and the oil (lipid layer) 116 floated and separated on the water surface of the processing region 105 is formed.
However, there is a possibility that the wastewater may flow out of the pipe 114 along with the untreated wastewater in the form of the overflow 117 beyond the partition plate 103 and into the outlet area 106.

[0005] In the case of using the diffuser tube 109 having a hole in the peripheral wall of a tube (cylindrical container), the bubbles released into the sewage are large, whereas the bubbles are reduced by using a static mixer to be aerobic. The release of microorganisms into sewage is itself disclosed, for example, in U.S. Pat. No. 5,102,104 to Reid.

The Raid et al. Patent discloses that a pump mounted at the top lid of a sewage treatment tank containing sewage into which aerobic microorganisms have been introduced pumps up the sewage in the tank and forms the sewage in the discharge pipe of the pump. Received reception room (receivi
ng chamber), the sewage discharged from the pump,
Mix with the air sent from the blower through the manifold, and further send the two-phase flow of sewage and air to the static mixer extending vertically downward through the downcomer, about a few microns with the static mixer The finely divided air bubbles are sent to the bottom of the tank together with the sewage through the downcomer, and discharged from the downcomer at the bottom of the tank having a depth of, for example, about 12 m (40 ft). It is disclosed that the sewage is treated by dissolving oxygen in the sewage while the sewage is being treated.

[0007] However, in this sewage treatment equipment, a static mixer is vertically connected for a long time to mix air with sewage in a downcomer, so that the pump is relatively low in power consumption. Therefore, it is necessary to discharge sewage by applying pressure to some extent, and a blower requiring power supply as an air flow generation source is required. Moreover, in order to disperse the oxygen dissolved in the sewage into the tank, the sewage circulation flow accompanying the discharge of the sewage from the outlet of the downcomer pipe extending to the bottom of the tank and the suction of the sewage in the suction pipe is mainly used Therefore, it is necessary to increase the discharge pressure of the pump so that the gas flows out at a somewhat high flow rate and outflow pressure.

On the other hand, an air injection nozzle is provided at the bottom of the sewage treatment tank so that air is ejected vertically upward from the nozzle, and sewage near the nozzle of the treatment tank is sucked by the ejected air flow to mix the air and water. The stream is sent vertically upward to a static mixer placed in the sewage, and the small air bubbled by the static mixer is mixed into small air bubbles through a cylinder extending vertically upward around the nozzle and the static mixer. Wastewater treatment equipment having a device for sending wastewater to
No. 6,086,045.

However, in this equipment, aerobic microorganisms are arranged on a contact material fixed and arranged at an interval outside the cylinder, and a sewage flow containing bubbles released from the cylinder near the water surface is applied to the contact material. It is thought that the wastewater is discharged from the static mixer quite vigorously, and the bubbles released together with the wastewater are relatively large (for example, about 1 mm). It is considered that there is a high possibility of occurrence.

[0010] In the circulating water purification apparatus for raising fish and shellfish, a breeding water stream pumped up and discharged by a pump is caused to flow upward through an ejector in order to bring ozone into contact with the breeding water in order to sterilize the breeding water with ozone. Allowing the ejector to draw ozone from an ozone gas supply,
The mixed stream ejected from the ejector flows vertically upward into the static mixer, and breeding water containing small ozone bubbles flows into the downcomer of the ozone catalytic cracking tank, and is discharged at the bottom of the catalytic cracking tank to sterilize the breeding water. This is disclosed in Japanese Patent Application Laid-Open No. Hei 8-131019.

However, this device is also considered to allow the breeding water to flow out of the static mixer at a certain flow rate, and ozone dissolves in the breeding water while flowing through the inflow pipe of the contact device in the form of a downcomer. Therefore, it is considered that the bubbles released from the static mixer are relatively large (about 1 mm).

[0012]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above points, and its object is to provide:
It is an object of the present invention to provide an apparatus and a method for dissolving oxygen in water in a tank capable of minimizing power consumption by minimizing energy consumption and reliably dissolving oxygen in water.

It is another object of the present invention to provide an apparatus and method for dissolving oxygen in tank water suitable for use in a sewage treatment tank such as a grease trap.

[0014]

According to the present invention, the above-mentioned object is achieved by disposing below one surface of a tank and near the surface of the tank, and forcing either one of water and air to flow. The other means of the water and the air is sucked in by the forced flow and the other of the water and the air is sucked and discharged in a state where the water and the air are mixed. A flow rate adjusting means for adjusting the flow rate of the fluid, and a water flow and a mixed flow of the air discharged from the injector means are arranged below and near the water surface of the tank, and the air in the mixed flow is finely divided. A static mixer that emits water under the surface of the tank and near the surface of the water with the water,
The flow rate adjusting means is adjusted such that a water flow discharged through the static mixer is smaller than a level at which the water in the tank is turbulently stirred, and the static mixer is discharged together with the water from the static mixer. This is achieved by means of a device which dissolves oxygen into the water of the tank configured, so that the air is broken down into fine bubbles which accompany the stream of water emitted from the static mixer.

In this specification, "injector means"
When one of the water and the air is forced to flow in, the forced flow can suck the other of the water and the air and release the water and the air in a mixed state. Any structure can be used as long as the fluid is forcibly introduced, but usually, the static pressure when one of the fluids forced to flow in ejects a narrow flow path such as a nozzle. With the other fluid,
It consists of allowing both fluids to flow out in a mixed state, and includes not only so-called "injectors" but also, for example, those sometimes called "ejectors" or "ejectors". If desired, a spiral groove may be formed in the peripheral wall of the tapered inflow passage of the injector means. The injector means is provided with water so that the amount of air taken in per unit time in the injector means or the flow rate of air flowing per unit time through the injector means is large enough to provide necessary dissolved oxygen. Alternatively, it is appropriately selected according to the flow rate of air.

The "flow rate adjusting means" adjusts the flow rate (volume or mass flow rate) of the fluid forcibly flowing into the injector means. Since the flow rate is determined in relation to the resistance, the fluid pressure at the time of outflow may be adjusted instead of the flow rate. However, the pressure of the fluid flowing out of the flow rate adjusting means depends on the flow rate-dependent resistance of the flow path located downstream of the adjusting means and the mixing characteristics depending on the flow rate or pressure of the injector means and the static mixer. In consideration of this, selection and adjustment are performed so as to have a predetermined size (level). Thus, the flow regulating means preferably has a (fluid pressure) accumulator-like characteristic, itself or in combination with a fluid source, so that the outgoing fluid pressure does not fluctuate during the flow regulation. Are preferred. For example, an outlet may be provided in a chamber directly connected to the main pipe or branch pipe of tap water in which the pressure is normally kept constant, and a means for adjusting the opening of the outlet may be provided as a flow rate adjusting means.
In addition, water may always be stored in a reservoir such as a tank to a certain depth, and water may be discharged from a bottom opening thereof, and a means for adjusting the opening of the bottom opening may be provided as a flow rate adjusting means. .

Regarding the flow rate adjusted by the flow rate adjusting means,
"The level of water discharged through the static mixer is smaller than the level at which the water in the tank is turbulently stirred."
Means that the water flow emitted from the static mixer arranged near the water surface of the tank does not cause the water in the tank to generate turbulence that makes the water surface greatly ruffled, and the water flow released from the static mixer is It means that it is not a high level (large flow rate (high flow velocity)) that flows almost linearly and creates a vortex around the inflow section,
Although depending on the size of the outlet of the static mixer, when the diameter of the outlet is about 1 cm, the flow velocity at the outlet of the static mixer is preferably 10 m / sec or less. Preferably, the flow rate is such that the water flow spreads calmly and quietly.
The fluid flows out of the outlet of the static mixer (as if it were diffusing), in which case the flow rate is
Preferably, it is about 0.1-2 m / sec.
It is very preferable if the speed is about 0.8 m / sec.

As a static mixer, the air in the gas-liquid mixture flow which has flowed in without using a power source can be miniaturized, the pressure loss is low, and the outflow pressure from the mixer is stably maintained and adjusted at a low level. As long as it can be obtained, its detailed structure and name may be anything, for example, it may be what is called a homogenizer, but in order to stably maintain and adjust the outflow pressure from the static mixer to a low level. In order to avoid a large fluctuation in pressure loss depending on the state of the gas-liquid mixed flow, it is preferable that the pressure loss is originally low. In a preferred embodiment described later, for example, the pressure loss is 10-20 kPa ( 0.1-0.2 kg / square cm) is used.

In this specification, the term "fine" with respect to bubbles refers to bubbles having a size small enough to allow oxygen in bubbles (actually bubbles of air) to be efficiently dissolved in water.
The size is 0.02 mm (20 microns) or less, more preferably 10 microns or less (for example, about 2 to 10 microns), and further preferably about several microns or less.

Regarding the static mixer, "below the water surface and near the water surface" means that the amount of water in the tank located above the outlet of the static mixer is far greater than the amount of water located below the outlet. A small amount, in practice, means a position that is 1/5 or less, preferably 1/10 or less, and when the fine bubbles emitted from the static mixer spread while descending with the water flow, most of the inside of the tank This means that the static mixer is arranged so that it can be in contact with water.

[0021]

Action and Effect 1 In the apparatus of the present invention, the fluid is disposed below and near the water surface of the tank, and either one of water and air is forcibly introduced and the forced flow is performed. Since the other fluid of the water and the air is sucked in by the injector means which is released in a state where the water and the air are mixed, the air can be easily taken into the injector means only. The air and water are effectively premixed by the injector means. Further, in the apparatus of the present invention, a mixed flow of water and air released from the injector means is caused to flow in, and the air in the mixed flow is discharged together with the water as fine bubbles under the water surface of the tank and near the water surface. Since the mixer is provided, the air in the mixed stream can be dispersed as fine bubbles in the water stream by the static mixer. Further, in the apparatus of the present invention, there is provided a flow rate adjusting means for adjusting a flow rate of the one fluid forcibly flowing into the injector means, and the flow rate adjusting means controls a flow of water discharged through the static mixer in the tank. Since the water is adjusted so as to be smaller than the level at which the water is turbulently stirred, there is no possibility that the water in the tank is turbulent due to the water flow discharged from the static mixer and the water surface is greatly ruffled.
In addition, in the apparatus of the present invention, the static mixer is disposed below and near the water surface of the tank, and water (for example, water having a lower temperature (larger specific gravity) than water near the water surface of the tank) is supplied from the static mixer. ) Is formed into fine air bubbles descending along with the water flow discharged from the static mixer, so that in the water near the water surface, the fine air bubbles descend along with the water flow. Therefore, even if the tank is shallow, oxygen in the bubbles can be dissolved into the water in the tank with high efficiency without making the water surface of the tank wave. Note that some of the fine bubbles gradually disperse and descend as if they were diffused away from the water flow.
The microbubbles that have reached the vicinity of the bottom of the tank gradually rise thereafter. The oxygen in the microbubbles dissolves into the water of the tank as the microbubbles descend and as the microbubbles rise again.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In an apparatus according to a preferred embodiment of the present invention, the static mixer is arranged so that a water stream containing microbubbles is discharged gently as it descends and spreads below a tank. It is configured.

[0023] In this case, the fine bubbles are sent down into the water of the tank along with the water flow that spreads calmly (as if they diffuse) while descending below the tank. Even if it is arranged very close to the water, the fine bubbles can be effectively dispersed in a wide range of the water and the oxygen can be effectively dissolved in the water without greatly waving the water surface. In this case, if the outlet diameter of the static mixer is about 1 cm,
The flow velocity from the outlet of the static mixer is preferably adjusted to be about 0.1 to 2 m / sec, typically about 0.8 m / sec.

In a preferred embodiment of the apparatus according to the present invention, the static mixer is configured to discharge water containing fine bubbles substantially horizontally.

In this case, almost all of the water in the tank from the vicinity of the water surface of the tank to the bottom of the tank can be uniformly and quickly dissolved with oxygen. Here, "almost horizontal direction"
The meaning is to exclude the water surface from rising (up) to the surface of the water so as to make the water surface rippling, or from falling downward without substantially expanding in the horizontal direction. You may. When the water in the tank is sucked by the submersible pump and sent to the ejector means as described later, the outlet of the static mixer may be directed downward to some extent (about 10 degrees or more in some cases). However, also in this case, the water flow including the fine bubbles from the static mixer is allowed to flow out in a substantially horizontal direction, preferably with a gentle and gentle flow.

In a preferred embodiment of the device according to the invention, the injector means is arranged to discharge the mixed flow of water and air in a substantially horizontal direction.

In this case, since the injector means can be located very close to the static mixer and located below and near the surface of the tank, the air taken in by the injector means and premixed before the water enters the static mixer. Can be minimized.

In a preferred embodiment of the apparatus according to the present invention, a water inflow means for forcibly injecting water into the injector means, one end is open to the atmosphere and one end is open to the air to guide suction of air into the injector means. Has an air conduit open to the water flow path in the injector means.

In this case, it is only necessary to make water flow into the injector means, and even if the injector means is arranged near the water surface, the water surface of the tank is less likely to be wavy.

In a preferred embodiment of the apparatus according to the invention, the water inflow means comprises a pipe connecting the water supply conduit to the injector means.

In this case, since it is sufficient to use only the water pressure of the tap water, there is no need to actually provide a power source, and no cost other than a tap water usage fee is imposed. Moreover, since the water flow from the static mixer is extremely small, the consumption of tap water can be minimized. In this case, the flow rate adjusting means may be any means for adjusting the outflow of tap water,
For example, a flow control valve always attached to a water tap may be used as flow control means, or a flow controller may be provided separately from the tap.

In a preferred embodiment of the apparatus according to the present invention, the water inflow means comprises a submersible pump arranged below the water surface of the tank and near the water surface to suck the water in the tank and discharge it to the injector means.

In this case, the apparatus can be used not only in a place where supply of tap water is difficult, but also consumption of tap water resources can be avoided.

In a preferred embodiment of the apparatus according to the present invention, an air inflow means for forcibly introducing air into the injector means, and one end is opened into the water in the tank to guide the suction of water into the injector means. A water conduit open at the other end to the air flow path in the injector means.

In this case, the apparatus can be used even in a place where supply of tap water is difficult. Further, since the water flow to be discharged from the static mixer can be suppressed to an extremely low level, the blower for generating the air flow needs to have a relatively low output.

In a preferred embodiment of the apparatus according to the present invention, a filter is provided in a flow path through which water in the tank flows into the injector means.

In this case, maintenance of the apparatus can be performed only by replacing the filter.

In one preferred embodiment of the apparatus according to the invention, the vessel comprises a grease trap.

In this case, the ripples on the sewage surface of the grease trap can be minimized, so that the oil (lipid layer) floating and separated on the sewage surface of the grease trap may be mixed again, or the grease trap treatment area may be removed. There is little risk that certain wastewater will enter the outlet area beyond the partition plate.

[0040]

According to the present invention, the above object is also achieved by mixing fine bubbles from a static mixer arranged in water and near a water surface of a liquid storage tank mainly composed of water. This is achieved by a method of gently discharging and allowing oxygen to dissolve into the water of the tank, so that the water stream descends while spreading into the water of the tank, and so that the fine bubbles descend while spreading along with the water stream. You.

[0041]

[Function and Effect 2] In this case, in the water near the water surface, fine bubbles are lowered along with the water flow spreading downward while descending the tank, so that the water surface of the tank is ruffled even if the tank is shallow. Without dissolving, oxygen in bubbles can be dissolved into the water in the tank with high efficiency.

[0042]

[Embodiment 2] In a preferred embodiment of the method according to the present invention, tap water is passed through injector means to create an air-enriched water stream, which is located below and near the surface of the tank. Through a static mixer, the water flow mixed with fine bubbles is gently discharged from the static mixer so as to descend while spreading in the water of the tank, and so that the fine bubbles descend in the water accompanying the water flow. Dissolve oxygen in the water in the tank.

In this case, in the water in the vicinity of the water surface, fine bubbles are lowered while spreading along with the water flow descending and descending below the tank, so that the water surface of the tank is ruffled even if the tank is shallow. Not only can the oxygen in the bubbles be dissolved into the water in the tank with high efficiency, but also it is only necessary to use the water pressure of the tap, so there is no need to actually provide a power source, and other than the usage fee for tap water No cost, and
Since the water flow from the static mixer is very small, tap water consumption can also be minimized. In this case, the flow rate of the tap water is adjusted by changing the opening of the flow control valve always attached to the tap, that is, by twisting the tap, separately from the tap. This may be performed by a flow controller provided.

In a preferred embodiment of the method according to the present invention, a water flow mixed with fine bubbles is spread from the static mixer disposed in the grease trap sewage and near the sewage surface into the grease trap sewage. Gently discharge to allow oxygen to dissolve into the grease trap's sewage as it descends and as the microbubbles descend into the sewage with the stream.

In this case, in the water near the surface of the water, fine bubbles are lowered along with the water flow that spreads while descending below the grease trap tank.
It is not only possible to dissolve the oxygen in the bubbles into the sewage of the tank with high efficiency without causing the sewage surface of the tank to be ruffled, but also it is only necessary to use the water pressure of the water supply. Absent. Further, since there is no cost other than the usage fee of tap water, and the water flow from the static mixer is extremely small, consumption of tap water can be minimized. In this case, the flow rate of the tap water is adjusted by changing the opening of the flow control valve always attached to the tap, that is, by twisting the tap, separately from the tap. This may be performed by a flow controller provided.
Also, since the ripples on the sewage surface of the grease trap can be minimized, the oil (lipid layer) floating and separated on the sewage surface of the grease trap may be mixed into the sewage again, or may be present in the treatment area of the grease trap. There is little risk that sewage will enter the exit area beyond the partition.

[0046]

Next, an example in which the apparatus for dissolving oxygen in water in a tank according to the first preferred embodiment of the present invention is applied to a sewage treatment tank such as a grease trap will be described with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a sewage treatment tank such as a grease trap, and the sewage treatment tank 1 dams floating substances such as oil (lipid layer), some other organic substances, and floating sludge. An inlet area 4 serving as an initial floating / separating tank by the partition plates 2 and 3, a processing area 5 serving as a floating / separating tank and also a reaction tank or an aeration tank, and a discharge for sending treated water to a final processing tank (not shown). It is divided into an outlet area 6 serving as a tank. These three areas or chambers 4, 5, 6 are communicated by communication paths 7, 8 below the partition plates 2, 3.
Waste water C to be treated is fed into the inlet area 4 of the treatment tank 1 via a conduit 9. In the part of the inlet area 4 into which the wastewater C flows, solid matter released together with the wastewater C is supplied to the tank 1.
Basket 4a (shown exaggerated and enlarged in the figure) is arranged to prevent entry into the processing area 5. The aerobic microorganism D is injected into the inlet area 4 periodically or as needed. A part of the oil (lipid) in the wastewater C is removed from the wastewater C through the communication passage 7 through the communication passage 7 from the inlet region 4 through the remaining portion E.
Before entering the treatment area 5 in the direction, it rises to the sewage surface 10 of the entrance area 4. Similarly, of the sewage E that has entered the treatment area 5 through the communication path 7, the oil (lipid) and the organic matter that has been buoyantly transformed by the aerobic microorganisms D are connected to the water G treated in the treatment area 5. Before entering the exit area 6 in the H direction through the passage 8, it rises to the water surface 11 of the treatment area 5. On the other hand, the treated water G that has entered the outlet region 6 is discharged through a conduit 12 to be sent to a terminal treatment tank (not shown).
For example, in the case of a 2 ton tank, about 50 to 70 tons of wastewater C per day flows in and is discharged as treated water G. When the wastewater C is kitchen wastewater, the wastewater C is almost concentrated during meals 2-3 times a day, and does not usually flow in at night. Therefore,
In the case of this 2 ton tank, for example, the time for which water stays in the tank 1 until it is discharged as the treated water G after flowing into the tank 1 as wastewater C is about 3 to 5 minutes at short time. During this time, floating and separation of oil and the like in the wastewater C are performed.

In FIG. 1, reference numeral 21 denotes a faucet 21c provided with a water supply pipe 21a as a water inflow means and a faucet cock 21b.
, 22 is a flow regulator as flow regulating means, 23 is a water pipe composed of pipes, 24 is an injector as injector means, 25 is an injector 24
An air conduit whose upper end is open to the atmosphere and whose lower end is connected to the injector 24 so as to guide the atmosphere to the injector 24, 26 is a static mixer, 27 is the injector 24 and the static mixer 2
This is a conduit that connects to 6.

The injector 24 is disposed below the water surface 11 of the tank 1 and in the vicinity of the water surface 11. The injector 24 supplies tap water J from the water pipe 21a to the faucet 21c and the flow rate at the faucet 21c. The forced flow of the tap water J through the adjuster 22 and the pipe 23 substantially horizontally in the K direction causes the air (air) L to be sucked in through the air conduit 25 by the forced flow of the tap water J.
And the air L are mixed and discharged substantially horizontally in the M direction. The flow regulator 22 regulates the flow rate N of the tap water J that is forced to flow into the injector 24 in the K direction. The flow regulator 22 may be disposed anywhere upstream of the injector 24, and may be disposed underwater, for example, as shown by the imaginary line in FIG.

The static mixer 26 is provided on the water surface 1 of the tank 1.
1 and in the vicinity of the water surface 11, a mixed flow P of water and air is discharged from the injector 24 via a relatively short horizontal conduit 27, and the air in the mixed flow P is removed. The fine bubbles Q are discharged together with the water J together with the water J under the water surface 11 of the treatment area 5 of the tank 1 and in the vicinity of the water surface 11 in a substantially horizontal direction. The conduit 27 may be straight or
The injector 24 may be bent like an L-shaped tube.
And the static mixer 26 are actually connected directly to the conduit 27
May be omitted.

The flow controller 22 is a static mixer 2
The water stream S discharged from the tank 6 is supplied to the water 18 in the treatment area 5 of the tank 1.
Is adjusted to be a water flow S that is smaller than the turbulent flow and agitates, and spreads gently and gently while descending below the processing area 5 of the tank 1.

The static mixer 26 has a fine bubble Q
The static mixer 26 is disposed so as to discharge the water containing the gas substantially horizontally in the R direction. The static mixer 26 moves the air in the gas-liquid two-phase flow P flowing down to below the processing area 5 of the tank 1. It is converted into fine bubbles Q that descend along with the water flow S that spreads calmly and quietly.

The static mixer 26 is, for example, as shown in FIG.
As shown in the figure, the inlet 31 includes an outlet 32, an enlarged body 33 between the inlet 31 and the outlet 32, and a baffle plate 35 disposed in a chamber 34 of the body 33. The gas-liquid mixed flow P entering in the direction M from the baffle 35 and the main body 33 in the chamber 34 of the enlarged main body 33 as shown by the arrow U.
To collide with the inner wall 36 and the baffle plate 35 or many times with each other to make the bubbles in the mixed flow P fine with the collision and to flow out in the form of a fluid flow T containing the fine bubbles Q. It is configured. As the static mixer 26, for example, a "super static mixer" (trade name) capable of suppressing pressure loss to about 0.1-0.2 kg / square cm.
It is preferable that a large number of small holes or concave portions are formed on the surface of the wall 36 or the baffle plate 35 against which the mixed flow collides, and that a large number of small unevenness forming slopes are used. In this static mixer 26, it was confirmed that the size of the bubbles Q in the discharged mixed flow T could be made about 2 microns. However, if the static mixer has a relatively small pressure loss and can reduce the flow velocity at the outlet, and can reduce the size of the bubble Q to 0.01 mm (10 microns) or less, preferably about several microns, The structure does not matter. If the flow rate (flow velocity) of the gas-liquid mixed flow passing through the static mixer 26 is too high, the mixed flow passes through the static mixer 26 in a short time, so that the air bubbles in the static mixer 26 are insufficiently miniaturized. Therefore, the size of the bubbles flowing out from the outlet 32 may be too large. Conversely, if the flow rate (flow velocity) of the gas-liquid mixed flow passing through the static mixer 26 is excessively reduced, the collision energy with respect to the inner wall 36 and the baffle plate 35 of the static mixer 26 becomes too small, so that the air bubbles are sufficiently reduced by the collision. Is not promoted, and the size of the bubbles flowing out of the outlet 32 becomes too large. Therefore, it is necessary to adjust the flow velocity of the mixed flow passing through the static mixer 26 to one suitable for miniaturization of bubbles according to the characteristics of the static mixer 26.

Regarding the outlet 32 of the static mixer 26, “below the sewage surface 11 and near the sewage surface 11” means that the amount of water in the treatment area 5 of the tank 1 located above the outlet 32 Also means a position that is much less than the amount of water located below, and in practice is less than 1/5, preferably less than 1/10, and the depth V of the tank 1 is 40-50.
cm, the depth W from the sewage surface 11 at the outlet 32 of the static mixer 26 is preferably about several cm,
When the depth V of the tank 1 is about 1-2 m, the depth W of the outlet 32 of the static mixer 25 is preferably 10-30 cm.
It is about. The diameter of the outlet 32 of the static mixer 26 is, for example, about 1 cm.
It may be larger than several cm or 10 cm or larger, or conversely smaller. The diameter and the depth V of the outlet 32 are selected according to the depth W of the tank 1 and the thickness of the suspended matter that accumulates on the dirty water surface 11 of the tank 1.

Next, the operation of the apparatus 40 configured to dissolve oxygen into the tank 1 (hereinafter also referred to as "oxygen injection apparatus") 40 will be described together with the operation of the tank 1 such as a grease trap. I do.

Wastewater C from a kitchen or the like is mainly fed into the inlet area 4 of the tank 1 through a conduit 9 in the daytime. The tank 1 is usually charged with the aerobic microorganism D before the oil and organic matter decomposition processing is performed during a period in which there is practically no inflow of wastewater at night. The microorganism D flows into the treatment area 5 in the F direction through the communication passage 7 with the flow of water in the tank 1 due to the inflow of the wastewater C from the conduit 9 and the discharge of the treated water G from the conduit 12. The water enters the outlet area in the H direction through the communication passage 8, and is then discharged together with the treated water.
The faucet 21c of the water supply 21 of the oxygen injection device 40 is usually
The tap water J, which is always open and adjusted to a flow rate of, for example, about 10 liters / minute by the flow rate regulator 22, has an outlet having a diameter of about 1 cm while taking in, for example, about 20% by volume of air L by the injector 24. Static mixer 26
Of the water flow S together with the fine bubbles Q.

The portion of the wastewater C flowing from the conduit 9 excluding highly buoyant lipids floating on the water surface 10 in the inlet area 4 is to be floated and separated, or to be decomposed by microorganisms such as activated sludge treatment. It flows into the processing area 5 of the tank 1 from the communication path 7 to receive the processing.

In the oxygen injecting device 40, the flow rate regulator (so that the flow rate of tap water which can originally flow at about 5-6 m / sec as seen at the outlet of the static mixer 26 at the end becomes about 2 m / sec). The tap water whose flow rate has been adjusted at 22 is supplied to the injector 24 near the sewage surface 11 of the treatment area 5 of the tank 1.
As it flows through it, atmospheric air L is sucked into the injector 24 via the air conduit 25 and into the static mixer 26 via the short conduit 27 in the form of a gas-liquid mixed flow (gas-liquid two-phase flow) P. It is sent in the M direction. In the static mixer 26, while the gas-liquid mixed flow (gas-liquid two-phase flow) P collides with the walls 35, 36 of the static mixer 26 many times, the air in the gas-liquid mixed flow (gas-liquid two-phase flow) P (Bubbles) are converted into fine bubbles Q of about 2 microns. The gas-liquid mixed flow (gas-liquid two-phase flow) P that has entered the static mixer 26 is substantially free of pressure loss, under the sewage surface 11 of the treatment area 5 of the tank 1 and in the vicinity of the sewage surface 11 ( For example,
When the depth of the tank 1 is about 40-50 cm, for example, several cm below the water surface 11), for example, at a low pressure of about 200 kPa (about 2 kg / square cm) and, for example, 2 m / cm 2
At a flow rate as small as a second (as if it were diffusing)
The water flow S including a large number of fine bubbles Q is caused to flow out in the horizontal direction R so as to spread quietly as “whim”.

The water stream S containing a large number of fine bubbles Q gently discharged in the R direction diffuses as if it were not stirred to make the sewage around the treatment area 5 of the tank 1 turbulent. Then, it descends while spreading calmly and quietly. Since the bubbles Q contained in the water flow S are fine, having a size of several microns, the buoyancy is small and the flow resistance is small. Descends below. still,
The present inventors have confirmed that the fine bubbles Q can gradually descend in the sewage 18 even in a state in which the water flow S has spread and practically no significant flow has disappeared. Although the cause is not necessarily clear, the flow S of the water receives a relatively large flow resistance from the water 18 itself of the tank, whereas the fine bubbles Q form the water 18
This is probably due to the relatively small flow resistance received from the vehicle. Since the air bubbles Q are fine, the surface area per volume is large, and oxygen in the air bubbles Q is easily removed from the wastewater 18.
As the bubble Q descends, a substantial portion of the oxygen in the bubble Q can dissolve into the sewage 18 because it can dissolve into it. The bubble Q that has reached near the bottom of the tank gradually rises again, and oxygen in the bubble Q dissolves into the water in the tank during the rise. Part of the nitrogen in the bubbles Q is dissolved, and the remaining portion gradually gathers to form large bubbles and rises to escape to the water surface 11. still,
The dissolved oxygen and the oxygen contained in the fine bubbles Q
Due to the gentle flow of water (including convection) and the mixing of water in the bath 8, the water is dispersed or diffused throughout the treatment area 5 of the tank 1, and during this dispersion or diffusion, most of the oxygen in the fine bubbles is dispersed. Can dissolve into the sewage 18.

The present inventors have proposed that the apparatus 40 can increase the dissolved oxygen concentration of 10 liters of tap water from 2 ppm to 8 pp in one minute.
m (saturated dissolved oxygen concentration at the temperature at the time of the test), and in the case of a 1-ton tank, the actual volume of 0.3 ton of sewage 18 is required in about 5 minutes for the minimum required for the biopharmaceutical (microorganism) D It was confirmed that the dissolved oxygen amount could be 2 ppm.
In the continuous operation of the device 40, the dissolved oxygen concentration of the sewage 18 of the tank 1 can always be maintained in the range of 3-8 ppm. The present inventors have also found that the efficiency of oxygen infusion, that is, the oxygen available to microorganisms among the oxygen released into the sewage in the form of air microbubbles Q (in practice, sewage in the form of dissolved oxygen) It has been confirmed that the amount of oxygen dissolved in the solution can be reduced to about 90%.

In the treatment area 5 of the tank 1, the aerobic microorganism D
However, it takes in dissolved oxygen to decompose sludge or to float on the sewage surface 11 of the tank 1 in the form of activated sludge. Sludge or oil that has surfaced can be effectively decomposed by the aerobic microorganisms D during the night.

During the above-described dispersion and infusion of oxygen by the apparatus 40, the sewage surface 11 of the treatment area 5 of the tank 1 is not actually ruffled, so that untreated sewage of the treatment area 5 of the tank 1 is removed. Not only is there a small risk of entering the exit area 6 beyond the partition plate 3, but also the sewage surface 1 of the first treatment area 5
There is little risk that the oil (lipid) or sludge floating and separated in 1 will be mixed again with water below the treatment area 5.

The sludge and oil on the sewage surface 10 in the inlet area 4 of the tank 1 can also be decomposed by the aerobic microorganisms D during the night.

The water from which the oil (lipid) has floated and separated in the treatment area 5 of the tank 1 enters the outlet area 6 through the communication passage 8 below the partition plate 3, and is discharged through the outlet pipe 12. You.

In the oxygen penetration device 40, the driving source is only the pressure or flow of tap water, and there is no need to use energy such as electric power.
Operating costs can be kept to a minimum. In the device 40,
Since large ground facilities are not required, there is no problem of installation space.

However, in the oxygen injection device according to the present invention, instead of using tap water as in the device 40 shown in FIG. 1 as the water inflow means, a pump 51 may be used as shown in FIG. Good. In the oxygen penetration device 50 of FIG.
Elements or members similar to those of the oxygen penetration device 40 shown in FIGS. 4 except that the submerged pump 51 sucks the sewage 18 on the deep side of the treatment area 5 of the tank 1 via the suction pipe 52 and sends it to the injector 24 via the discharge pipe 53. Thus, the configuration is the same as that of the device 40 shown in FIGS. 5
4 is a filter. This filter 54 is connected to the pump 5
Instead of the suction side 1, it may be provided in the discharge pipe 53. still,
In this case, when the water discharged from the static mixer 26 is difficult to spread downward with respect to the surrounding water (for example, when there is no specific gravity difference due to the water temperature or other causes), the outlet of the static mixer 26 is set to a certain extent (in some cases). Is 10
It may be directed downward. In addition, as long as it can be operated continuously at a relatively low discharge pressure and stably for a long time,
The pump 51 may be of a type located above the sewage level 11 of the tank 1, but by adopting a submersible pump, it is not necessary to secure a place for installing the apparatus on the ground. Flow rate N of water 18 flowing into injector 24
In practice, in this case, the flow rate adjusting means is provided by the pump 51 itself or a regulator of the power supply voltage of the pump 51 (not shown). It is. If desired, a flow controller 55 may be provided on the discharge side of the pump 51, for example, as indicated by an imaginary line.

Although the oxygen injection device 50 requires pump driving energy such as electric power, the efficiency of oxygen injection is high, so that the power consumption is reduced to a fraction of that of the conventional device shown in FIG. Can be suppressed. Further, since the device 50 does not require tap water, it can be used in places where there is no tap water or where the tap water pressure is abnormally low and tap water is difficult to use.

In the oxygen injection device according to the present invention, air may be forced to flow into the injector means instead of water. In the oxygen injection device 60 of FIG. 5, the same elements or members as those of the oxygen injection device 40 or 50 are denoted by the same reference numerals. The oxygen penetration device 6 of FIG.
At 0, the air L in the atmosphere sucked from the intake pipe 62 by the blower 61 as the blower means is forced to flow into the injector 24 through the blower pipe 63, and the airflow flowing through the throttle passage in the injector 24 , The sewage 18 in the treatment area 5 of the tank 1 is sucked through the suction pipe 64 so that the gas-liquid mixed flow is discharged from the injector 24 to the conduit 27. It is configured similarly to. In the oxygen injection device 60, the flow rate of the air L flowing into the injector 24 can be actually adjusted by adjusting the power supply to the blower 61. Therefore, in this example, the flow rate adjusting means is a blower. 6
1 or a regulator (not shown) of the power supply voltage of the blower 61. If desired, a flow regulator 65 may be provided on the discharge side of the blower 61, for example, as indicated by an imaginary line.

The apparatus and method of the present invention can be used to treat not only wastewater containing animal and vegetable oils such as kitchen wastewater but also wastewater containing mineral oil such as industrial wastewater by appropriately selecting microorganisms. May also be applied.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an example in which an apparatus for dissolving oxygen in a tank is applied to a sewage treatment tank such as a grease trap according to a preferred embodiment of the present invention.

FIG. 2 is a block diagram showing a basic configuration of the apparatus shown in FIG.

FIG. 3 is an explanatory sectional view of an example of a static mixer used in the apparatus of FIG. 1;

FIG. 4 is a block diagram similar to FIG. 2 for a modification of the apparatus of FIG. 1;

FIG. 5 is a block diagram similar to FIG. 2 for another modification of the apparatus of FIG. 1;

FIG. 6 is a schematic explanatory view showing an example in which a conventional oxygen penetration device is applied to a sewage treatment tank such as a grease trap inside the tank.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sewage treatment tank 2,3 Partition plate 4 Inlet area 4a Basket 5 Processing area 6 Exit area 7,8 Communication path 9 Conduit 10,11 Sewage surface 12 Conduit 18 (Dirty) water in treatment area 21 Water supply 21a Water supply pipe 21b Faucet Cock 21c faucet 22 flow regulator 23 pipe (water supply pipe) 24 injector 25 air conduit 26 static mixer 27 conduit 31 inlet 32 outlet 33 enlarged body 34 chamber 35 baffle plate 36 inner wall 40 oxygen injection device (oxygen in the tank) 50 Oxygen injection device (device for dissolving oxygen in the tank) 51 Submersible pump 52 Suction pipe 53 Discharge pipe 54 Filter 55 Flow rate regulator 60 Oxygen injection device (device for dissolving oxygen in the tank) 61 Blower 62 Intake pipe 63 Blast pipe 64 Water absorption pipe C Wastewater D Aerobic microorganism E Wastewater (wastewater in tank) Part) F Flow direction G Treated water H Flow direction J Tap water K direction L Atmosphere (air) M direction N Water flow rate P Mixed flow Q Fine bubbles R direction S Water flow T Fluid flow including fine bubbles U Arrow ( Flow direction at the time of collision) V Depth of tank W Depth of outlet of static mixer

Claims (13)

[Claims] 1. A fluid is disposed below and near the water surface of a tank, and one of water and air is forcibly introduced and the forced flow of water and air is caused by the forced flow. Injector means that the other fluid is sucked and discharged in a state where water and air are mixed, flow rate adjusting means for adjusting the flow rate of the one fluid forcibly flowing into the injector means, The mixed flow of water and air discharged from the injector means is introduced near the water surface, and the air in the mixed flow is discharged as fine bubbles together with the water below the water surface of the tank and near the water surface. A static mixer, wherein the flow rate adjusting means is smaller than a level at which a water flow discharged through the static mixer turbulates and stirs water in the tank. The static mixer is configured such that the air discharged together with the water from the static mixer is formed into fine bubbles descending with the flow of water discharged from the static mixer. A device for dissolving oxygen in water. 2. The apparatus according to claim 1, wherein the static mixer is configured to gently discharge the water flow including the fine bubbles so as to descend and expand below the tank. 3. The apparatus according to claim 1, wherein the static mixer is configured to discharge water containing fine bubbles in a substantially horizontal direction. 4. Apparatus according to claim 1, wherein the injector means is arranged to discharge the mixed stream of water and air in a substantially horizontal direction. 5. A water inflow means for forcing water to flow into the injector means, and one end is open to the atmosphere and the other end is open to a water flow path in the injector means for guiding suction of air into the injector means. An apparatus according to any one of the preceding claims, comprising an air conduit. 6. The apparatus according to claim 5, wherein the water inflow means comprises a pipe connecting a water supply conduit to the injector means. 7. The apparatus according to claim 5, wherein the water inflow means comprises a submersible pump disposed below the water surface of the tank and in the vicinity of the water surface to suck water in the tank and discharge the water to the injector means. 8. An air inflow means for forcing air into the injector means, and an air flow opening in the tank at one end and an air flow in the injector means at the other end for guiding suction of water into the injector means. 5. A device according to any one of the preceding claims, comprising a water conduit open to the road. 9. The apparatus according to claim 7, wherein a filter is provided in a flow path through which water in the tank flows into the injector means. 10. The apparatus according to claim 1, wherein the tank comprises a grease trap. 11. A static mixer disposed underwater and near a water surface of a liquid storage tank mainly composed of water,
A method in which oxygen is dissolved into the water in the tank by gently discharging so that the water flow mixed with fine bubbles descends while spreading into the water of the tank, and the fine bubbles descend into the water accompanying the water flow. . 12. A water stream containing air is made by passing tap water through an injector means, and the water stream is passed through a static mixer located below and near the water surface of the tank to form a water stream containing fine bubbles. A method of gently discharging oxygen from a static mixer to dissolve oxygen into the water of a tank so that the water descends while spreading in the water and fine bubbles descend along with the water flow. 13. A static mixer disposed in the sewage of the grease trap and in the vicinity of the sewage surface, so that the water flow mixed with the fine bubbles descends while spreading into the sewage of the grease trap, and A method in which oxygen is dissolved into the sewage of the grease trap by releasing it gently so that it descends into the sewage following the water flow.