JP3744425B2 - Membrane separation wastewater treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a membrane separation wastewater treatment apparatus, and more specifically, the activated sludge mixed liquid does not flow back to the air diffuser in the membrane separation wastewater treatment apparatus, and air can be suitably supplied to the activated sludge mixed liquid. The present invention relates to a membrane separation wastewater treatment apparatus including a diffusible apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a wastewater treatment apparatus that purifies wastewater with microorganisms, a solid-liquid separation apparatus using membrane separation is provided to separate activated sludge and treated water. In this solid-liquid separation device by membrane separation, a device for supplying air is provided in the reaction water tank, and the activated sludge adhering to the membrane element is washed by utilizing the force of rising bubbles.
An example of a conventional air diffuser is shown in FIG. The air diffuser 60 includes a blower 65, a communication pipe 66, and a perforated pipe 68, and the blower 65 and the perforated pipe 68 are connected by the communication pipe 66. Further, the perforated pipe 68 is a pipe provided with an air vent hole 69 of several millimeters downward, and the air sent from the blower 65 passes through the communication pipe 65 and the air vent hole 69 of the perforated pipe 68. To the reaction tank 18.
The air discharged from the perforated pipe 68 becomes bubbles and rises while dissolving oxygen in the activated sludge mixed liquid stored in the reaction tank 18, and acts to clean the membrane element 42 of the membrane separator. .
[0003]
[Problems to be solved by the invention]
Since the diffuser in the conventional membrane separation wastewater treatment apparatus uses the perforated pipe 68 as the diffuser pipe, only bubbles with coarse particles can be formed, and the efficiency of dissolving oxygen in the activated sludge mixture is low. In order to enable stable biological treatment with microorganisms, it is necessary to supply a large amount of air, leading to an increase in blower power.
Further, when the operation of the blower is stopped, the perforated pipe 68 sucks the activated sludge mixed solution from the hole 69, so that the perforated pipe 68 may be clogged. When the perforated pipe 68 is clogged, not only the air supply to the activated sludge mixed solution becomes insufficient and the biological treatment efficiency is deteriorated, but also the membrane element 42 is not sufficiently washed. This greatly hinders stable operation of the wastewater treatment apparatus, such as shortening the life of the element 42.
[0004]
Therefore, measures such as enlarging the diameter of the hole 69 provided in the perforated pipe 68 are taken. However, if the diameter of the hole 69 is increased, the bubbles become coarse and suitable for cleaning the membrane element 42. On the other hand, there is a problem that the oxygen dissolution efficiency with respect to the activated sludge mixed liquid decreases. Therefore, a fundamental solution has not yet been reached, such as the occurrence of other problems such as a further increase in the power of the blower 65 required to stably perform biological treatment.
[0005]
The present invention has been made to solve such problems. In the aeration apparatus of the membrane separation wastewater treatment apparatus, the membrane element can be efficiently washed, and oxygen can be efficiently introduced into the treatment tank. Dissolvable, and even when the blower operation is stopped, the activated sludge mixed liquid flows backward to prevent clogging of the diffuser pipe, thereby enabling energy-saving and stable operation. An object of the present invention is to provide a membrane separation wastewater treatment apparatus.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, a membrane separation wastewater treatment apparatus according to the present invention has the following configuration.
That is, a reaction tank that purifies wastewater with microorganisms, a solid-liquid separation device that is immersed in the reaction tank and has a membrane element for solid-liquid separation of the activated sludge mixed liquid, and a lower part of the membrane element in the reaction tank In the membrane separation wastewater treatment apparatus configured to be provided with an air diffuser for supplying air to the reaction tank, the air diffuser includes a box with an open bottom and an upper plate of the box up and down. A bubble discharge pipe that is attached to the box, a communication pipe that communicates with the inside of the box, and a blower that is connected to the communication pipe. The lower end of the bubble discharge pipe is slash-cut. In addition, the lower end portion of the bubble discharge pipe is disposed lower than the tip end portion of the communication pipe inside the box body, and the air supplied from the blower forms an air layer in the box body, and the air layer is interposed therebetween. Air is supplied to the bubble discharge tube. A membrane separation wastewater treatment apparatus characterized by being.
Thereby, even when the blower of the air diffuser is stopped, it becomes possible to prevent the activated sludge mixed liquid from flowing backward and clogging the air diffuser. Further, when a plurality of bubble discharge tubes are connected to the box, it is possible to discharge air evenly from the respective bubble discharge tubes. Furthermore, since the volume of air blown out from the air discharge pipe can be adjusted by adjusting the blower output, it is possible to arbitrarily set the size of bubbles, cleaning membrane elements and oxygen to activated sludge. When supplying, it became possible to perform both efficiently.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a membrane separation wastewater treatment apparatus according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an explanatory view showing a membrane separation wastewater treatment apparatus.
[0008]
In the present embodiment, an example in which the membrane separation wastewater treatment apparatus is applied to a nitrification / denitrification apparatus including a denitrification tank and a nitrification tank will be described.
Reference numeral 10 denotes a nitrification / denitrification device. The nitrification / denitrification apparatus 10 includes a reaction tank 18 including a denitrification tank 14 and a nitrification tank 16 partitioned by a partition plate 12, a waste water storage tank 30 for storing waste water 20 flowing into the reaction tank 18, and a reaction tank 18. A membrane element 42 for solid-liquid separation of the activated sludge mixed liquid 40 denitrified and nitrified by the above, a pump 50 for sucking the treated water solid-liquid separated by the membrane element 42, and supplying air to the nitrification tank 16 An aeration device 60 for performing the above and a pump 70 for refluxing the activated sludge mixed solution 40 in the nitrification tank 16 to the denitrification tank 14.
[0009]
The wastewater storage tank 30 stores wastewater from which large waste has been removed by a screen. The waste water 20 stored in the waste water storage tank 30 is sequentially supplied to the denitrification tank 14 through a pipeline 32 that connects the waste water storage tank 30 and the denitrification tank 14 by controlling the amount of water supplied by the control unit. The amount of water supplied to the denitrification tank 14 is controlled by the control unit so as to be equal to the amount of treated water discharged from the reaction tank 18 by the pump 50, and the amount of water stored in the reaction tank 18 is always constant. To be controlled.
[0010]
In the anaerobic state, the wastewater 20 flowing into the denitrification tank 14 is decomposed and denitrified by the action of denitrifying bacteria in the activated sludge. A pump 80 is disposed at the bottom of the denitrification tank 14 and performs stirring and mixing in the denitrification tank 14.
[0011]
The activated sludge mixed liquid 40 that has passed through the denitrification tank flows into the nitrification tank 16 through the communication path 82 sandwiched between the partition plates 12 and 12. The nitrification tank 16 is for nitrifying the activated sludge mixed liquid 40. In this nitrification treatment, ammonia nitrogen in the activated sludge mixed solution 40 is nitrified into nitric acid by nitrifying bacteria under an aerobic condition. Subsequently, the activated sludge mixed solution 40 that has been nitrified in the nitrification tank 16 is sent back to the denitrification tank 14 again, whereby the nitrogen component in the activated sludge mixed solution 40 is released into the atmosphere as nitrogen gas, and nitrogen is removed.
[0012]
The activated sludge mixed liquid 40 from which nitrogen has been removed again in the denitrification tank 14 is sent again to the nitrification tank 16 and again subjected to nitrification treatment. In the nitrification tank 16, the membrane element 42 is used to take out the treated water from the activated sludge mixed solution 40. The treated water is obtained by solid-liquid separation of the activated sludge contained in the activated sludge mixed liquid 40.
In the present embodiment, a membrane separation system using a membrane element 42 and a pump 50 is employed as a solid-liquid separation device.
[0013]
As described above, the denitrification tank 14 is denitrified under an anaerobic condition, and the nitrification tank 16 is nitrified under an aerobic condition. It is preferable to provide a check valve (not shown) in the communication passage 82 that communicates to clarify the distinction between the anaerobic state and the aerobic state in each tank.
[0014]
The membrane element 42 is connected to a water intake pipe 54 connected to the pump 50 via a check valve 52, and the pump 50 discharges treated water separated from the membrane element 42 by solid-liquid separation. Information on the discharge amount of the treated water is transmitted to a control unit (not shown), and the control unit controls the amount of waste water 20 flowing from the waste water storage tank 30 into the denitrification tank 14.
The check valve 52 prevents the treated water in the intake pipe 54 from flowing back into the nitrification tank 16 when the operation of the pump 50 is stopped after the purified water is discharged by the pump 50. is there.
[0015]
A circulation pipeline 72 for sending the activated sludge mixed solution 40 in the nitrification tank 16 back to the denitrification tank 14 communicates with the lower part of the nitrification tank 16. The circulation pipeline 72 is provided with a pump 70, and the activated sludge mixed solution 40 treated by the nitrification tank 16 flows again into the denitrification tank 14 via the circulation pipeline 72 by the pump 70. The As a result, the activated sludge mixed liquid 40 is circulated sequentially from the denitrification tank 14 to the nitrification tank 16 and from the nitrification tank 16 to the denitrification tank 14, thereby obtaining highly treated water.
[0016]
Since the activated sludge mixed solution 40 treated in the nitrification tank 16 has increased oxygen solubility, if it is returned to the denitrification tank 14 as an anaerobic tank as it is, the organic matter to be used for the denitrification reaction in the denitrification tank 14. Causes an oxidation reaction, and the efficiency of the denitrification process decreases. Therefore, it is preferable to dispose the dissolved oxygen removal device 74 in the middle of the circulation pipeline 72 to remove the dissolved oxygen from the activated sludge mixed solution 40 to be returned to the denitrification tank 14 and return it.
[0017]
FIG. 2 is a perspective explanatory view showing the structure of an air diffuser installed below the membrane element in the nitrification tank.
The air diffuser 60 includes a box body 61 whose lower portion is open, a bubble discharge pipe 62, and a blower 65 that blows air into the box body 61.
The bubble discharge pipe 64 is provided so as to protrude upward and downward from the upper plate 61a of the box body 61, and communicates the inside of the box body 61 with the nitrification tank 16.
In the present embodiment, the bubble discharge pipe 64 is composed of an air suction pipe 63 and an air blow pipe 62, and the air blow pipe 62 is formed with a diameter larger than that of the air suction pipe 63. The base is formed in a tapered surface that gradually decreases in diameter downward, and the air suction pipe 63 is connected to the air blowing pipe 62. Reference numeral 64a denotes a communication hole opened on the side surface of the connecting portion with the air suction pipe 63 at the base position of the air discharge pipe.
[0018]
A communication pipe 66 is provided in communication with the side surface of the box body 61. The communication pipe 66 extends in the vertical direction in the box body 61, and the front end is located near the lower surface of the upper plate 61a. Here, in the box body 61, the positional relationship between the lower end portion of the air suction pipe 63 and the distal end portion of the communication tube 66 is set so that the distal end portion of the communication tube 66 is at a higher position.
When air is supplied to the box body 61 from the blower 65 connected to the other end side of the communication pipe 66, the box body 61 is filled with air, and an air layer is formed in the box body 61. The aeration apparatus of the membrane separation wastewater treatment apparatus according to the present invention supplies air to the air suction pipe 63 through the air layer and discharges air bubbles from the air blowing pipe 62 to the nitrification tank 16, so that the membrane element 42 and the active device are activated. Air is supplied to the sludge mixture 40.
Since a communication hole 64 a communicating with the nitrification tank 16 is provided on the side surface of the bubble discharge pipe 64, the air bubbles are discharged from the bubble discharge pipe 64 while mixing the air and the activated sludge mixed liquid 40 in the nitrification tank 16. Is released.
[0019]
As described above, in the inside of the box body 61, the tip end portion of the communication pipe 66 is disposed at a position higher than the lower end portion of the air suction pipe 63, so that when the operation of the blower 65 is stopped, the nitrification tank Even if 16 activated sludge mixed liquids 40 enter the box 61 from the bubble discharge pipe 64, the air trapped in the box 61 remains in the box 61 as it is, and the tip of the communication pipe 66 in the air layer. Since the activated sludge mixed liquid 40 does not enter the communication pipe 66, the air can be stably supplied to the membrane element 42 and the activated sludge, thereby extending the life of the membrane element 42. And the efficiency of biological treatment is greatly improved.
In the communication pipe 66, a check valve may be provided between the blower 65 and the box body 61 so as to check the air in the box body 61.
[0020]
FIG. 3 is an arrow view of the air discharge pipe 62 in FIG. In the opening of the upper end of the air discharge pipe 62 in the present embodiment, a cross-shaped partition plate 62b is disposed. The partition plate 62 b mixes the air sucked from the air suction pipe 63 and the activated sludge mixed solution 40 of the nitrification tank 16 sucked from the communication hole 64 a of the bubble discharge pipe 64, and the air blown out from the air blowing pipe 62. It works to make bubbles fine.
If the partition plate 62b formed in a cross-like shape is provided in this way, the air bubbles supplied to the nitrification tank 16 are made finer, so that the oxygen solubility can be increased and the nitrification treatment with activated sludge is efficient. Will be made. Note that the mechanism for refining the bubbles is not limited to this, and for example, there is another form in which a large number of protrusions protruding from the inner wall of the air blowing pipe 62 toward the center of the air blowing pipe 62 are disposed. Of course.
[0021]
FIG. 4 is an explanatory view of an air suction pipe in the membrane separation wastewater treatment apparatus according to the present invention. The point that the tip shape of the air suction pipe 63 is slash-cut is different from the previous embodiment. By slash-cutting the lower end portion of the air suction pipe 63, the position of the water surface, that is, the position of the air layer varies according to the output of the blower 65. As a result, the volume of the air layer in the box 61 changes and the opening area of the tip of the air suction pipe 63 changes, so that the amount of air supplied from the air blowing pipe 62 can be adjusted. When the blower output is increased, the space of the air layer in the box body 61 is increased, and the opening area of the air suction pipe 63 is increased, so that the amount of air supplied from the air blowing pipe 62 is also increased. The bubbles supplied in this manner are effective when the membrane element 42 is cleaned.
On the other hand, when the blower output is lowered, the space of the air layer in the box body 61 is reduced, and the opening area of the air suction pipe 63 is reduced, so that the amount of air supplied from the air blowing pipe 62 is reduced. In this case, since the bubbles supplied from the air blowing pipe 62 are reduced, the oxygen dissolution efficiency is improved, and the air supply is effective when supplying oxygen to the activated sludge.
According to the air diffuser of the present embodiment, it is possible to control the cleaning of the membrane element 42 and the two air supplies that contradict the oxygen dissolution efficiency with a single blower.
[0022]
FIG. 5 is an explanatory view showing another embodiment of the air suction pipe. A feature of this embodiment is that a slit 63a is provided at the tip of the air suction pipe 63. The slit 63 a is formed in a long hole shape extending from the tip of the air suction pipe 63 in the length direction of the air suction pipe 63. By providing such a slit 63a, the opening area of the slit 63a varies depending on the depth at which the air suction pipe 63 is immersed in water, and the air suction pipe 63 has a tip that is slash-cut. In addition to obtaining the effect of making it possible to adjust the amount of air discharged, the air is disturbed when the air passes through the slit 63a, and the air bubbles are easily miniaturized inside the air suction pipe 63. It works effectively to improve oxygen solubility.
[0023]
FIG. 6 is an explanatory view showing an embodiment in which a bubble distribution plate is disposed between a box body and a membrane element of an air diffuser. The bubble distribution plate 67 is provided with bubble release tubes 64 corresponding to each of the membrane elements 42, and the bubble distribution plate 67 is provided so as to partition each bubble release tube 64. Thus, by providing at least one bubble discharge pipe 64 corresponding to one membrane element 42, air can be evenly supplied to each membrane element 42. As a result, the problem that the activated sludge adhering to the membrane element 42 cannot be removed without air being supplied to a part of the membrane element 42 can be solved, and the pump can be damaged. Therefore, stable wastewater treatment becomes possible.
Further, since all of the air supplied from the bubble discharge pipe 64 passes through the membrane element 42 and is supplied to the nitrification tank 16, oxygen is supplied to the nitrification tank 16 after the membrane element 42 is reliably cleaned, Air can be used effectively, which is preferable.
[0024]
【The invention's effect】
As described above, according to the membrane separation wastewater treatment apparatus according to the present invention, even if the blower is stopped, the activated sludge mixed liquid does not flow back into the aeration apparatus, so that the clogging of the aeration apparatus is prevented. be able to. Therefore, it becomes possible to always supply air stably to the activated sludge and the membrane element . Also, since are slash cut tip of the air suction duct, it is possible to adjust the end opening area of the air suction tube in accordance with the output of the blower, optionally adjusting the size of the bubble supplying be able to.
As a result, it becomes possible to selectively supply air for cleaning the membrane element and supplying oxygen to the activated sludge mixed solution with a single blower, so that the membrane separation wastewater treatment can be operated stably. It becomes possible, and the manufacturing cost of the membrane separation wastewater treatment apparatus can be reduced.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a membrane separation wastewater treatment apparatus .
FIG. 2 is a perspective explanatory view showing the structure of the air diffuser.
FIG. 3 is an arrow view of the air discharge tube in FIG. 2;
FIG. 4 is an explanatory view of an air suction pipe in the membrane separation wastewater treatment apparatus according to the present invention .
FIG. 5 is an explanatory view showing another embodiment of the air suction pipe.
FIG. 6 is an explanatory view showing an embodiment in which a bubble distribution plate is disposed between a box body of a diffuser and a membrane element.
FIG. 7 is an explanatory diagram showing a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Nitrification / denitrification apparatus 14 Denitrification tank 16 Nitrification tank 18 Reaction tank 30 Waste water storage tank 42 Membrane element 50, 70, 80 Pump 60 Air diffuser 61 Box 62 Air blowing pipe 62b Partition plate 63 Air suction pipe 63a Slit 64 Bubble Release pipe 64a Communication hole 65 Blower 66 Communication pipe 67 Distribution plate 72 Circulating pipeline 74 Dissolved oxygen removing device

Claims (1)

A reaction tank that purifies wastewater with microorganisms, a solid-liquid separation device that is immersed in the reaction tank and has a membrane element for solid-liquid separation of the activated sludge mixed liquid, and disposed below the membrane element in the reaction tank In the membrane separation wastewater treatment apparatus constituted by a diffuser for supplying air to the reaction tank,
The air diffuser includes: a box having an open bottom; a bubble discharge pipe attached through the upper plate of the box up and down; a communication pipe provided in communication with the box; and a communication pipe And a blower connected to
The lower end portion of the bubble discharge pipe is slash-cut, and the lower end portion of the bubble discharge pipe is disposed lower than the distal end portion of the communication pipe inside the box, and the air supplied from the blower is in the box A membrane separation wastewater treatment apparatus, wherein an air layer is formed in the body, and air is supplied to the bubble discharge pipe through the air layer.

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