JPH10151475A - Contact oxidation type biological treatment equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] Air can be introduced into an oxidation tank as uniform fine bubbles, and uniform upward flow is formed while preventing the formation of large-diameter bubbles due to the association of bubbles, thereby improving efficiency. To obtain a catalytic oxidation type biological treatment apparatus capable of performing good catalytic oxidation. SOLUTION: When introducing a liquid to be treated 4 into an oxidizing tank 1 for performing catalytic oxidation by attaching activated sludge to a carrier, an ejector 2 is provided.
Air is sucked into 1 and mixed, and the mixed liquid is stirred and pressurized by a pump 22 to make air bubbles finer and dissolved to be introduced into the oxidation tank 1, thereby forming a uniform upward flow and efficiently contacting. While oxidizing, the carrier is prevented from rising to the liquid level and closing the mesh plate 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact oxidation type biological treatment apparatus in which a carrier is present in an oxidation tank and oxidation is performed by aeration, in particular, a contact oxidation apparatus in which air is sucked by an ejector to perform aeration. The present invention relates to an oxidation type biological treatment apparatus.

[0002]

2. Description of the Related Art In a catalytic oxidation type biological treatment apparatus, a carrier is present in an oxidation tank to cause activated sludge to adhere and hold at a high density.
By utilizing this, efficient catalytic oxidation is performed, and the organic effluent is treated. Such a catalytic oxidation type apparatus includes a biological filtration apparatus which uses a particulate carrier in a floating state and performs catalytic oxidation and filtration using a fixed carrier.

[0003] In a contact oxidation type biological treatment apparatus using a floating carrier, when the liquid to be treated flows in an upward flow, the carrier is pushed up due to aeration and leaks together with the treated water. Is performed. In this case, the liquid to be treated is supplied from the upper part of the aeration tank, aerated from the lower part to float the carrier, and the treated water is taken out from the lower part of the floating carrier. However, in this method, the carrier tends to settle, and it is difficult to suspend the settled carrier again.

[0004] When the liquid to be treated is caused to flow upward, a method of covering the surface of the oxidation tank with a mesh plate or a grid plate that allows only water to pass therethrough or preventing the treated water from overflowing is used to prevent the carrier from flowing out. A method of installing a mesh plate near the treated water trough is adopted. However, the suspended carrier is clogged with the pores of the mesh plate or grid plate and closed.

FIG. 2 is a cross-sectional view of a conventional contact oxidation type biological treatment apparatus of the floating type using an upward flow. In FIG. 2, 1
Denotes an oxidation tank, in which a support floor 2 is provided at a lower part of the inside, and a liquid passage 4 to be treated communicates with an introduction chamber 3 at the lower part thereof;
An air diffuser 5 is provided, to which an air supply path 6 communicates. A grid plate 7 is provided in the vicinity of the liquid surface of the oxidation tank 1, and a processing liquid trough 9 is provided slightly above the grid plate 7 so as to form an overflow wall 8, and a processing liquid path 10 communicates therewith. The granular carrier 1 is contained in the in-tank liquid 11 on the support bed 2 in the oxidation tank 1.
2 has been thrown.

In the processing method using the above-described apparatus, when the liquid to be processed is supplied from the liquid path 4 to be processed, the air is supplied from the air supply path 6, and the air is diffused from the air diffuser 5, the air becomes bubbles. The liquid to be treated and the bubbles pass through the support bed 2 in an upward flow to float the carrier 12. Thereby, the activated sludge adhering to the carrier 12 is repeatedly contacted with the liquid to be treated and the air to perform the catalytic oxidation. The processing liquid passes through the grid plate 7, overflows from the overflow wall 8 into the processing liquid trough 10, and is taken out to the processing liquid path 10.

In such a conventional upward oxidation type catalytic oxidation biological treatment apparatus, air supplied from the lower part of the oxidation tank 1 is blown through an air diffuser 5 such as a diffuser bulb or a slit plate. The air at the moment of leaving the air diffuser 5 is 0.1 to 0.1.
It becomes a bubble with a diameter of 5 cm. Since the rising speed of bubbles having such a diameter is 100 to 300 m / hr and turbulence does not occur, carrier particles heavier than water having a specific gravity of 1.01 to 1.30 do not rise to the water surface. .

However, depending on the state of turbulence, small-diameter bubbles that have normally exited the air diffuser 5 grow by association to 1 to 5 cm.
Large diameter bubbles. Such bubbles are between 500 and 120
Since the rising speed is as high as 0 m / hr, the carrier 12 rises to the vicinity of the liquid level by being caught in the rising flow, and closes the mesh plate or the grid plate 7. As a result, since the treated water does not flow, there is a problem that it takes time for maintenance work such as peeling of the treated water.

[0009] Instead of the above-mentioned floating system, even in a fixed-bed type biological filtration apparatus in which a carrier is used in a fixed state and catalytic oxidation and filtration are performed, when large-diameter bubbles rise, they adhere to the carrier. Sludge peels off and flows out with the treated water,
There is a problem that the filtration function is hindered.

[0010]

An object of the present invention is to enable air to be introduced into the oxidation tank as uniform fine bubbles,
An object of the present invention is to provide a catalytic oxidation type biological treatment apparatus capable of forming a uniform upward flow and performing catalytic oxidation while preventing generation of large-diameter bubbles due to association of bubbles.

[0011]

According to the present invention, there is provided an oxidation tank for receiving an organic effluent and contacting it with activated sludge for aeration.
A carrier present in the oxidation tank and holding the activated sludge, a liquid passage to be supplied to the lower part of the oxidation tank to supply the liquid to be treated, an ejector provided to suck air into the liquid passage to be treated, and air And a pump that agitates and pressurizes the liquid to be treated into which the liquid has been sucked, breaks up and dissolves bubbles, and supplies the gas to the oxidation tank.

In the present invention, the oxidizing tank is configured to receive the organic effluent and aerate by contacting the effluent with the activated sludge, and the carrier is present in the oxidizing tank and adheres and holds the activated sludge. It is configured as follows. Such an oxidation tank is preferably of a floating type in which the granular carrier is used in a floating state, but may be of a fixed bed type in which the carrier is fixed. The structure of the oxidation tank can be the same as that of a general catalytic oxidation type biological treatment apparatus that has been conventionally used.

The floating oxidation catalytic biological treatment apparatus has a structure in which a granular carrier is charged on a support bed and the carrier is suspended by an upward flow. The apparent specific gravity of the carrier is 1.0
Those having a diameter of 1-1.30, preferably 1.05-1.20 and a particle size of 0.5-10 mm, preferably 1-3 mm can be used. Examples of such a granular carrier include activated carbon and zeolite. As a means for preventing carrier outflow,
Although a mesh plate is preferably provided near the overflow wall provided at the top, a grid plate may be provided along the liquid surface.

When a fixed type carrier is used, a honeycomb,
An arbitrary support such as a saddle or a ring can be filled in the oxidation tank to form a packed layer of the support. When a floating particulate filter medium is used, a liquid-permeable and gas-permeable support bed is provided above the oxidation tank, and the granular filter medium is pressed against the support bed in an upward flow to form a packed bed of carriers. Such a floating carrier has an apparent specific gravity of 0.90 to 1.10, preferably 0.95 to 1.0.
5. Particles having a particle size of 2 to 50 mm, preferably 3 to 10 mm can be used. Examples of such a carrier include plastics having a low specific gravity, such as polyethylene and polypropylene, and foams of general plastics.

The carrier is used in a state where activated sludge is adhered and proliferated and maintained at a high density. To adhere activated sludge in this way, the carrier is put into an oxidation tank, and organic wastewater and air are discharged. It is possible by introducing and performing processing.
In another apparatus, the carrier to which the sludge has already adhered may be pulled out and used.

In the present invention, the liquid passage to be treated is connected to the lower part of the oxidation tank so as to supply the liquid to be treated. An ejector is provided to introduce air into the liquid passage to be treated, and the air sucked by the ejector is provided. And the liquid to be treated is stirred and mixed and pressurized,
A pump is provided to break up and dissolve the bubbles and supply them to the oxidation tank. As the pump, a pump of a type that forcibly pushes a liquid, such as a centrifugal disk pump and a centrifugal disk pump with a suction screw that does not cause cavitation, is preferable.

The amount of air mixed into the liquid to be treated is determined by the concentration of organic matter (load) in the liquid to be treated. In this case, if the amount of air is larger than the amount of the liquid to be treated, the air cannot be dispersed into fine bubbles. Can be increased. In this case, the ratio of air to the liquid mixed with air is 10 to 100, preferably 20 to 50.

In the treatment method using the above-described apparatus, a carrier and activated sludge are charged into an oxidation tank, an organic waste liquid is supplied from a liquid passage to be treated, air is sucked into the ejector by an ejector, and mixed therewith. Stir the mixture of processing solution and air,
By mixing and pressurizing, the bubbles are subdivided and dissolved to be supplied to the oxidation tank, and the liquid is passed upward to perform the catalytic oxidation. If this state is continued, sufficient oxygen is supplied and the contact between the carrier and the air is gentle, so that the activated sludge multiplies and adheres to the carrier.

When the liquid to be treated is supplied to the ejector, air is sucked in by the suction action and mixed into the liquid to be treated. The mixed liquid is sucked into the pump, and the bubbles are fragmented by the stirring force, and a part of the bubbles is dissolved in the liquid to be treated by the pressing force. Here, the discharge pressure of the pump is a gauge pressure of 10 to 50 KPa, preferably 20 to 30 KPa.

The liquid to be treated supplied from the pump is 20 to 1
It is a gas-liquid mixture in which bubbles of 00 μm are uniformly dispersed. Such fine bubbles have a large surface area to easily dissolve oxygen, increase the oxidation efficiency, and make it difficult to associate because no turbulence occurs, and rise at a uniform speed of 5 to 20 m / hr. Less likely to occur.

For this reason, when the mixed solution is passed in an upward flow, the carrier in the oxidation tank is maintained in a uniform floating state in the case of the floating system, and a part thereof does not rise to the surface due to the turbulent flow, and the carrier adheres. Since the sludge thus separated is not easily separated, there is little possibility that the mesh plate or the like for preventing the carrier from flowing out will be blocked. The ascending flow rate in the oxidation tank varies depending on the specific gravity of the carrier and other conditions, but can be 5 to 100 m / hr, preferably about 10 to 50 m / hr.

In the case of a fixed bed, there is no problem of clogging due to the rise of the carrier, but the fine and uniform bubbles rise, so that the sludge adhering to the carrier does not peel off due to turbulence, and the filtration by the carrier packed bed. There is no inhibition of action.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a floating oxidation catalytic oxidation type biological treatment apparatus according to an embodiment of the present invention, and the same reference numerals as those in FIG. 2 indicate the same or corresponding parts.

In FIG. 1, an oxidation tank 1 is provided with a support floor 2 at a lower portion inside thereof, and a liquid passage 4 to be treated is introduced into an introduction chamber 3 therebelow.
Communicate with each other via an ejector 21 and a pump 22. A mesh plate 23 is provided near the overflow wall 8 provided above the oxidation tank 1. A circulating fluid passage 24 having a valve 25 branches off from the treatment fluid passage 10 communicating with the trough 9 and communicates with the fluid passage 4 to be treated. Activated carbon as a granular carrier 12 is charged into the in-tank liquid 11 on the support bed 2 in the oxidation tank 1. The air supply path 6 communicates with the ejector 21 so as to suck air. As the pump 22, a centrifugal disk pump is used.

In the processing method using the above apparatus, when the liquid to be processed is supplied from the liquid path 4 to be processed and air is supplied from the air supply path 6, the air is sucked from the ejector 21 and mixed and dispersed in the liquid to be processed. I do. The gas-liquid mixture enters the pump 22 and is further agitated, and the bubbles are fragmented and simultaneously pressurized to partially dissolve. Since the pump 22 is a centrifugal disk pump, liquid is forcibly pumped and cavitation does not occur.

The liquid to be treated in which fine air is dispersed is supplied to the oxidation tank 1
From the introduction hole 3 through the support floor 2 to float the carrier 12. Thereby, the activated sludge adhering to the carrier 12 is repeatedly contacted with the liquid to be treated and the air to perform the catalytic oxidation. At this time, the bubbles are finely and uniformly dispersed, and no large-diameter bubbles are generated due to association, so that the rising speed of the bubbles is low, turbulence does not occur, and the carrier is prevented from rising near the liquid level. You.

The processing liquid that has risen near the liquid surface is
3, overflows from the overflow wall 8 to the processing liquid trough 9, and is taken out from the processing liquid path 10, but a part of the liquid circulates from the circulating liquid path 24 and enters the processing liquid path 4 and mixes with the processing liquid. Is done. By circulating the processing liquid in this manner, a large amount of air can be mixed and dispersed in the ejector 21.
When the concentration of the organic substance in the liquid to be treated is low, for example, BOD 50m
When the flow rate is less than g / l, the circulation is not required.

Since the treatment liquid taken out of the treatment liquid passage 10 contains the separated activated sludge, it is separated into solid and liquid in a solid-liquid separation tank (not shown) and the separated liquid is discharged. Is returned to the oxidation tank 1.

Since large-diameter bubbles are not generated in the oxidation tank 1, the carrier does not normally rise to the liquid level, and the mesh plate 2 is used to prevent the carrier from flowing out due to a sudden abnormality.
Although 3 is provided near the overflow wall, clogging of the mesh plate 23 does not occur. Even in this case, the grit plate 7 may be provided as shown in FIG.

The above embodiment is an example of a floating-type catalytic oxidation type biological treatment apparatus, but it is also applicable to a fixed-bed type catalytic oxidation type biological treatment apparatus having a fixed carrier. In this case, the liquid in which the fine air bubbles are dispersed uniformly rises, and turbulence does not occur, so that the activated sludge adhering to the carrier is prevented from being separated, and the biological filtration action is not hindered.

[0031]

According to the present invention, air is sucked into the liquid to be treated by the ejector and mixed, and the gas-liquid mixture is agitated and pressurized by the pump to break up and dissolve the bubbles, and then to the oxidation tank. As it is introduced, air can be introduced into the oxidation tank as uniform microbubbles, and uniform upward flow is formed and efficient contact is made while preventing the formation of large-diameter bubbles due to the association of bubbles. Oxidation can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a contact oxidation type biological treatment apparatus according to an embodiment.

FIG. 2 is a sectional view of a conventional catalytic oxidation type biological treatment apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oxidation tank 2 Support floor 3 Introducing chamber 4 Liquid path to be processed 5 Air diffuser 6 Air supply path 7 Grid plate 8 Overflow wall 9 Processing liquid trough 10 Processing liquid path 11 Liquid in tank 12 Carrier 21 Ejector 22 Pump 23 Mesh plate 24 Circulating fluid passage 25 Valve

Claims (1)

[Claims] 1. An oxidation tank for receiving an organic waste liquid and contacting it with activated sludge for aeration, a carrier present in the oxidation tank for holding the activated sludge, and supplying a liquid to be treated to a lower part of the oxidation tank. Liquid path to be processed, an ejector provided to suck air into the liquid path to be processed, and the liquid to be processed into which the air has been sucked is stirred and pressurized to break up and dissolve bubbles and supply the resultant to the oxidation tank. And a contact oxidation type biological treatment apparatus.