JP2010131481A - Air diffusion apparatus for and method for aeration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air diffusion apparatus and a method for aeration which can remove deposited dried sludge without installing additional devices such as a line for a washing liquid and an atmospheric relief valve and without stopping aeration. <P>SOLUTION: The air diffusion apparatus blows gas for aeration into water to be treated 10 in an aeration tank 8 from a plurality of aeration holes of an air diffusing pipe immersed in the water to be treated 10. The air diffusing pipe 12 includes an aeration portion 16 formed with the aeration holes 28, and an introduction portion 14 formed with a fluid introduction port 18, fluidly communicating with the aeration portion and disposed below the aeration portion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention generally relates to an aeration apparatus and method for aeration, and more particularly to an aeration apparatus and an aeration method for use in a standard activated sludge treatment apparatus, a membrane separation activated sludge treatment apparatus, and the like.

  In an air diffuser used in sludge treatment or the like, an air diffuser tube in which a plurality of air diffuser holes are formed is used to aerate sludge to be treated or a liquid containing sludge (treated water). In such an air diffuser, sludge that has entered from the air diffuser accumulates in the tube and around the air diffuser and dries, thereby blocking part or all of the air diffuser, and possibly the air diffuser, Proper aeration may not be possible.

In order to cope with such problems, there is known a device for providing a cleaning liquid line and periodically injecting the cleaning liquid from the cleaning liquid line into the diffuser pipe to remove dry sludge accumulated in the diffuser pipe and the diffuser holes. (See Patent Document 1).
In addition, use a diffuser tube with a tip bent downward and an opening larger than the diffuser hole at the tip, periodically stop aeration, and set the diffuser tube at atmospheric pressure to the diffuser tube. There is also known an apparatus that introduces water to be treated and wets and removes dry sludge accumulated in the diffuser pipe and in the vicinity of the diffuser holes (see Patent Document 2).

  In addition, using a diffuser tube with a hole in the bottom, aeration is periodically stopped, and the treated water is introduced into the diffuser tube by bringing the diffuser tube to atmospheric pressure. An apparatus for removing dried sludge accumulated in the vicinity of a hole is also known (see Patent Document 3).

JP 2004-305886 A JP 2002-307091 A US Pat. No. 7,186,343

However, the apparatus provided with the cleaning liquid line has a problem that the equipment is expensive because it is necessary to additionally provide the cleaning liquid injection line.
In addition, the apparatus that periodically stops aeration to bring the inside of the air diffuser to atmospheric pressure has a problem that aeration must be temporarily stopped when removing the dried sludge. In addition, since an air release valve or the like for setting the air diffuser to atmospheric pressure is required, there is a problem that the equipment is expensive.

  Furthermore, in a device in which a hole is provided at the bottom of the air diffuser and sludge flows into the air diffuser, the difference between the water head between the air diffuser for aeration gas ejection and the hole for sludge inflow cannot be made large. There was a problem that the range of conditions under which the aeration gas was not ejected from the inflow hole was small, and the degree of freedom in design was low.

  The present invention has been made to solve such a problem, and can remove the volume of dried sludge without providing additional equipment such as a cleaning liquid line or an air release valve, and without stopping aeration. An object of the present invention is to provide an aeration device and an aeration method for aeration.

According to the present invention,
An aeration apparatus for ejecting gas for aeration into the water to be treated from a plurality of air diffusion holes of a diffusion pipe immersed in the water to be treated in an aeration tank,
The air diffuser includes an air diffuser in which the air diffuser hole is formed, and an introduction unit in fluid communication with the air diffuser and disposed below the air diffuser and having a liquid inlet formed therein. Yes,
An air diffuser characterized by the above is provided.

  According to such a configuration, sludge or a liquid containing sludge (treated water) is introduced into the diffuser pipe from the liquid inlet without stopping aeration, that is, introduction of gas into the diffuser pipe. Since the water to be treated is introduced into the air diffusing pipe from the liquid introduction port while introducing the gas into the air diffusing pipe in this way, the gas-liquid mixed liquid such as the gas and the water to be treated is caused by the air lift effect of the introduced gas. The dried sludge is efficiently removed by flowing into the diffuser.

  According to another preferred aspect of the present invention, the air diffuser hole is provided vertically above the air diffuser.

According to another preferred aspect of the present invention, the liquid inlet is provided vertically below the inlet.
According to the configuration, since the aeration gas does not spout from the liquid inlet, the amount of gas that can be introduced into the diffuser pipe increases while flowing the water to be treated from the liquid inlet into the diffuser pipe. To do.

According to another aspect of the invention,
Using any one of the aeration devices, aeration gas is continuously supplied to the aeration tube, and water to be treated flows into the aeration tube from the liquid inlet of the introduction unit. To erupt into the treated water,
An aeration method characterized by the above is provided.

  According to such a configuration, since the wet state is always maintained in the air diffuser and in the vicinity of the air diffuser hole, the air diffuser hole is less likely to be blocked with dry sludge. Further, even when foreign matter adhered and dried exists in the vicinity of the diffuser hole, the foreign matter is wetted by the treated water flowing into the diffuser pipe and is discharged from the diffuser hole. .

According to another aspect of the invention,
Using any of the above air diffusers,
A first step of causing the water to be treated to flow into the air diffusing pipe from the liquid introduction port while supplying the gas for diffusing to the air diffusing pipe, and jetting into the water to be treated in the aeration tank;
Repeating the second step of supplying the gas supply amount per unit time supplied into the diffuser pipe in an amount smaller than the supply amount per unit time in the first step,
An aeration method characterized by the above is provided.

  According to such a configuration, when the gas supply amount is smaller than that in the first step, in the second step, more water to be treated can be taken into the diffuser pipe and the dried sludge and the like can be moistened. Further, in the first step where the gas supply is relatively large, moistened dry sludge and the like are washed away by the gas. Furthermore, since the sludge in the air diffuser is removed at regular time intervals, efficient air diffusion can be performed.

According to another aspect of the invention,
Using any of the above air diffusers,
A first step of causing the water to be treated to flow into the air diffusing pipe from the liquid introduction port while supplying the gas for diffusing to the air diffusing pipe, and jetting into the water to be treated in the aeration tank;
Repeating the second step of supplying the supply pressure of the gas supplied into the air diffuser at a lower pressure than the supply pressure in the first step,
An aeration method characterized by the above is provided.

  According to such a configuration, in the second step where the gas supply pressure is lower than that in the first step, more water to be treated can be taken into the air diffuser and wet dry sludge and the like can be moistened. Further, in the first step where the gas supply pressure is relatively high, wet dried sludge and the like are washed away by the gas. Furthermore, since the sludge in the air diffuser is removed at regular time intervals, efficient air diffusion can be performed.

Hereinafter, a configuration of an air diffuser according to a preferred embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a drawing schematically showing a configuration of a wastewater treatment apparatus 1 equipped with an air diffuser according to a preferred embodiment of the present invention.
The waste water treatment apparatus 1 is an apparatus provided with a solid-liquid separation membrane element 6 connected to a pump 4 via a pipe line 2, but the air diffuser of the present invention can be combined with other waste water treatment apparatuses. is there.

  As shown in FIG. 1, the solid-liquid separation membrane element 6 is immersed in the water to be treated 10 which is wastewater containing sludge accommodated in the aeration tank 8. Further, below the solid-liquid separation membrane element 6, an air diffuser 12 that constitutes the air diffuser according to a preferred embodiment of the present invention is disposed. The air diffuser 12 is a “fishing hook” -like tubular member. In addition, although described as a cylindrical shape in FIG. 1, it may be a tubular member such as a substantially rectangular parallelepiped.

  2 is a side view of the air diffusing tube 12, and FIG. 3 is a cross-sectional view taken along line III-III in FIG. As shown in FIGS. 1 to 3, the short leg 14 is placed on its side with the long leg 16 on the bottom, and the short leg 14 and the long leg 16 on the long side. The leg portion 16 is connected by a connecting portion 15 extending in the vertical direction.

The shorter leg portion 14 is an introduction portion 14 in which a plurality of openings (liquid introduction ports) 18 are formed on the lower side surface (vertically below). The introduction part 14 has a gas intake part 19 at the tip side, and a lid 21 having an opening to which the pipe line 20 is connected is attached to the gas intake part 19, and the pipe line 20 connected to the opening is connected thereto. The aeration gas is introduced from the front end side.
In the illustrated embodiment, the conduit 20 has a smaller diameter than the introduction portion 14, but the present invention is not limited to this, and the conduit 20 may have substantially the same diameter as the introduction portion 14.
The operation of the blower 22 is controlled by an inverter 26 connected to a control unit 24 such as a computer.

  On the other hand, the longer leg portion 16 disposed above is in fluid communication with the introduction portion 14 and has a plurality of aeration holes 28 for ejecting aeration gas introduced into the introduction portion 14 on the upper side surface (vertically upward). It is considered as an air diffuser in preparation. The tip of the air diffuser 16 is closed with a cap 17.

  There is no particular limitation on the number and shape of the air holes 28, but a diameter of 2 to 15 mm is preferable. If the diameter is 2 mm or less, it is not preferable because it is likely to be blocked by impurities (particularly fibrous impurities) or solids present in the water to be treated. If the diameter is 15 mm or more, the balance of gas ejection from each air diffuser 28 is not preferable. This is not preferable because of the bias.

  It is preferable that the air diffuser hole 28 is provided at a position above the air diffuser 16 in the vertical direction. May be.

  The number and shape of the liquid inlets 18 are not particularly limited, but preferably 2 to 15 mm in diameter. If the diameter is 2 mm or less, it is not preferable because it is likely to be clogged by the thickness or solid content present in the water to be treated. Since it squirts, it is not preferable.

  The position of the liquid introduction port 18 may be any position of the introduction part 14 as long as it is lower than the air diffusion hole 28, but is preferably provided on the lower surface of the introduction part 14. This is because if the liquid introduction port 18 is provided on the upper side of the introduction unit 14, the aeration gas is ejected from the introduction unit 14, and the amount of water to be treated from the introduction unit 14 may be reduced.

  The height difference between the air diffuser hole 28 and the liquid inlet 18 is not particularly limited, but is preferably 5 to 50 cm. If it is 5 cm or less, the pressure difference acting on the air diffuser hole 28 and the liquid inlet 18 becomes small, so that when the gas is ejected from the air diffuser 28, the gas is also ejected from the liquid inlet 18. In the case of 50 cm or more, a large pressure is required to transfer the gas-liquid mixture of the water to be treated sucked from the liquid inlet 18 and the aeration gas sent from the blower 22 to the diffuser 16, and the blower 22 This is because the amount of energy consumption increases.

Next, the operation of the air diffuser according to a preferred embodiment of the present invention will be described.
The aeration apparatus of the present embodiment allows the treated water 10 to flow into the aeration pipe 12 from the liquid introduction port 18 while supplying the aeration gas to the aeration pipe 12 under the control of the control unit 24, and in the aeration tank 8. The first step (sludge removal step) to be ejected into the treated water 10 and the aeration gas to the diffuser pipe 12 at a higher pressure while supplying the treated water from the liquid inlet 18 into the diffuser pipe 12. The second step (aeration step) for ejecting water into the water to be treated 10 in the aeration tank 8 is repeated without flowing in.
In the second step, a relatively small amount of water to be treated may flow into the diffuser 12 from the liquid inlet 18.

  In the sludge removal step, the gas supply pressure from the blower 22 is set lower than that during normal aeration, and the pressure in the introduction unit 14 is made lower than the pressure of the water to be treated 10 in the aeration tank 10 (as a result, the amount of gas supply) Decreases from normal aeration). As a result, the water to be treated 10 enters the introduction part 14 through the liquid introduction port 18.

  Since the liquid introduction port 18 is provided below the diffuser hole 28, a larger pressure (water pressure) acts on the liquid introducer port 18 than the diffuser hole 28, and the treatment is performed from the liquid inlet 18 to the introduction unit 14. Water flows in.

  The water to be treated that has entered the introduction portion 14 becomes a gas-liquid mixed solution by the air lift effect by the gas supplied from the blower 22 in the connection portion 15 extending in the vertical direction, and flows into the diffuser portion 16. The treated water that has flowed into the air diffuser 16 is ejected from the air diffuser hole 28 of the air diffuser 16. The dried sludge accumulated in the vicinity of the air diffuser hole 28 is wetted with the water to be treated and is discharged from the air diffuser hole 28 together with the gas-liquid mixture.

  As a result, in the sludge removal step, it is possible to moisten the inside of the air diffusion pipe 12 to suppress the sticking of the sludge, or to wet and remove the accumulated dry sludge and to discharge these sludge from the air holes. It becomes.

  The duration of the sludge removal step is not particularly limited, but is preferably 1 to 5 minutes. In less than 1 minute, the water to be treated cannot be allowed to flow in enough to sufficiently wet the inside of the air diffuser tube 12, so that the effect of preventing sludge sticking cannot be obtained. In more than 5 minutes, the solid-liquid separation membrane element is washed. This is because there is a problem in that the amount of gas supplied is insufficient and the membrane surface is clogged, and the necessary amount of oxygen for biological treatment cannot be supplied.

  Moreover, there is no restriction | limiting in the supply amount of the gas in a sludge removal step, Although it does not restrict | limit in particular, It is preferable that it is 20 to 70% of the supply amount in an aeration step. If it is less than 20%, the water to be treated flowing from the liquid introduction port 18 cannot be sufficiently distributed in the air diffuser 12, and if it is 70% or more, the pressure in the introduction part 14 is not sufficiently reduced. This is because a sufficient amount of water to be treated cannot be introduced from the liquid inlet 18.

In the aeration step, by increasing the flow rate or supply pressure of the gas per unit time supplied from the blower 22 in the sludge removal step and increasing the pressure in the air diffuser 12, the water to be treated is scattered from the liquid inlet 18. Without flowing into the trachea 12, the gas supplied from the blower 22 is jetted into the water to be treated 10 in the aeration tank 8 from the air diffusion hole 28.
As a result, the dried sludge and the like wetted in the sludge removal step are pushed away by the gas and removed from the vicinity of the air diffuser hole 28.

  In the aeration step, it is preferable to introduce the gas at a high pressure or a high flow rate without causing the water to be treated to flow into the diffuser pipe from the liquid introduction port 18 because sludge can be removed more efficiently. In this step, the water to be treated may flow into the air diffuser as long as the pressure resistance is not a problem.

  The duration of the aeration step is not particularly limited, but is preferably 5 to 300 minutes, more preferably 10 to 60. If it is 5 minutes or less, clogging of the membrane surface proceeds due to insufficient gas supply for cleaning the solid-liquid separation membrane element, and if 300 minutes or more, the inside of the air diffuser 12 is dried and diffused. This is because the hole 28 and the liquid inlet 18 are blocked by the dried sludge.

  The amount of gas supplied in the aeration step is equal to or higher than the flow rate at which the gas for aeration can be evenly ejected from any one of the plurality of the aeration holes 28, and is used for solid-liquid separation. The flow rate is not less than a flow rate at which the membrane element 6 is sufficiently washed, and the flow rate is less than the water pressure acting on the liquid introduction port 18 to prevent the gas for aeration from being ejected from the liquid introduction port 18. To do.

  Although gas supply control is performed by controlling the inverter 26 by the control part 24 and changing the rotation speed of the blower 22, valve operation may be used. Further, a compressor may be used instead of the blower 22.

  According to such a configuration, in the sludge removal step, since the pressure in the introduction unit 14 is lower than that in the aeration step, more water to be treated flows into the introduction unit 14 from the liquid introduction port 18 than in the aeration step. If the gas flow rate is 20% or more at the time of the aeration step, the water to be treated that has flowed into the introduction unit 14 is treated as a gas-liquid mixture of the water to be treated and the introduced air due to the air lift effect of the supplied gas. It flows into the air diffuser 16.

  When switching to the aeration step after the sludge removal step, the pressure in the air diffuser 16 increases, and the wet dry sludge that has flowed into the air diffuser 16 is contained in the liquid to be treated together with the gas supplied from the air diffuser hole 28. Is erupted. The dried sludge adhering to the air diffuser hole 28 and its periphery is also moistened by the water to be treated that has flowed into the air diffuser 16, and into the liquid to be treated from the air diffuser 28 together with the gas that has flowed into the air diffuser 16. Erupted.

  The air diffuser hole 28 may be provided in the lower part of the air diffuser 16, but is preferably provided in the upper part. Due to the structure in which the air diffuser hole 28 is provided in the upper part of the air diffuser 16, the water to be treated flowing from the liquid inlet 18 is preferentially aerated from the air diffuser hole 28 on the water to be treated inflow side of the air diffuser 16. 8 is prevented from being ejected into the interior of the air diffuser 16, and the water to be treated can be ejected from the air diffuser hole 28 on the side opposite to the sludge inflow side.

Next, the configuration of the air diffusing tube of the air diffusing device according to the second embodiment of the present invention will be described. FIG. 4 is a side view of the air diffuser 30 of the air diffuser according to the second embodiment.
As shown in FIG. 4, the air diffuser 30 includes an air diffuser 32 disposed above, and an inlet 34 bent laterally from a lower end of a connecting portion 33 depending from the center of the air diffuser 32. It has. A plurality of air diffusion holes 36 and liquid introduction holes 38 are formed in the air diffusion part 32 and the introduction part 34, respectively.
Further, both ends of the air diffuser 32 are closed, and a pipe line 20 connected to a blower is connected to the tip of the introduction part 34.

  In such a structure, the distance to the air diffuser hole 36 farthest from the position where the water to be treated flows into the air diffuser 32 is reduced, so that the water to be treated and the gas are more evenly distributed to each air diffuser hole 36. The

Next, the configuration of the air diffusing tube of the air diffusing device according to the third embodiment of the present invention will be described. FIG. 5 is a side view of the air diffuser 40 of the air diffuser according to the third embodiment.
As shown in FIG. 5, the air diffuser 40 includes an air diffuser 42 disposed at an upper position, and an introductory part bent laterally from a lower end of a connecting part 43 depending from both ends of the air diffuser 42. 44. A plurality of aeration holes 46 and liquid introduction holes 48 are formed in the aeration unit 42 and the introduction unit 44, respectively.
Furthermore, the distal end portion of the introduction portion 44 is bent upward, and the pipe line 20 connected to the blower is connected to the distal end.

  In such a configuration, since the distance from the position where the water to be treated flows into the air diffuser to the air diffuser hole 46 farthest is reduced, the water sludge and the gas to be treated are more evenly distributed to each air diffuser hole 46. Is done.

  The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention.

Example 1
Next, examples of the present invention will be described. A filtration test was performed using a membrane treatment apparatus using a solid-liquid separation membrane element as shown in FIG.
As the membrane element for solid-liquid separation, Sterapore SADF (trade name, manufactured by Mitsubishi Rayon Engineering Co., Ltd., hollow fiber membrane made of polyvinylidene fluoride) was used. The liquid to be treated was activated sludge with a sludge concentration (SS concentration) of about 10,000 mg / L.

  1 is formed with a vinyl chloride circular tube having an inner diameter of 30 mm and a length of 600 mm. Six diffuser holes with a diameter of 5 mm are provided in the upper portion, and a sludge suction port with a diameter of 5 mm is provided at the introduction portion. What provided three places in the lowest part was used. The height difference between the air diffuser and the introduction part was 15 cm. A Roots blower was used as a blower, and a gas for aeration was supplied to the aeration tube.

  Using an inverter, the gas flow rate for aeration is 100 L / min as a high flow rate (aeration step) for 15 minutes, and 50 L / min, which is 50% of the high flow rate as a low flow rate (sludge removal step) for 1 minute. The cycle was fed to the diffuser.

As a result of aeration for 60 days under the above operating conditions, sludge blockage was not confirmed in all of the six diffuser holes provided in the diffuser. Also, no sludge blockage was observed at the liquid inlet.
Also, no sludge sticking was confirmed inside the air diffuser 2.

(Comparative Example 1)
All the conditions except that the sludge suction port is not provided and the continuous supply is performed without performing an intermittent cycle are the same as in Example 1. As a result of aeration for 60 days, 6 aerations provided in the aeration unit Blockage was confirmed at four of the holes.
In addition, sludge sticking was confirmed inside the air diffuser 2.

(Comparative Example 2)
The conditions other than the continuous supply of the gas flow rate for the air diffuser without performing an intermittent cycle were the same as in Example 1, and as a result of aeration for 60 days, 6 air diffuser holes provided in the air diffuser Obstruction was confirmed at 4 points.

BRIEF DESCRIPTION OF THE DRAWINGS It is drawing which shows typically the structure of the waste water treatment equipment 1 provided with the aeration apparatus which is one of the embodiments of this invention. It is a side view of the diffuser tube used for the diffuser of FIG. It is sectional drawing along the III-III line of FIG. It is a side view of the diffuser tube of the diffuser of 2nd Embodiment. It is a side view of the diffuser tube of the diffuser of 3rd Embodiment.

Explanation of symbols

12: Air diffuser 14: Introduction part 16: Air diffuser 18: Liquid inlet 28: Air diffuser hole

Claims (6)

An aeration apparatus for ejecting gas for aeration into the water to be treated from a plurality of air diffusion holes of a diffusion pipe immersed in the water to be treated in an aeration tank,
The air diffuser includes an air diffuser in which the air diffuser hole is formed, and an introduction unit in fluid communication with the air diffuser and disposed below the air diffuser and having a liquid inlet formed therein. Yes,
A diffuser characterized by that. The air diffuser hole is provided vertically above the air diffuser;
The aeration apparatus according to claim 1. The liquid inlet is provided vertically below the inlet;
The aeration apparatus according to claim 1 or 2. The aeration apparatus according to any one of claims 1 to 3, wherein aeration gas is continuously supplied to the aeration tube, and water to be treated is supplied into the diffusion tube from a liquid inlet of the introduction unit. And let it flow into the treated water in the aeration tank.
An aeration method characterized by that. Using the air diffuser according to any one of claims 1 to 3,
A first step of causing the water to be treated to flow into the air diffusing pipe from the liquid introduction port while supplying the gas for diffusing to the air diffusing pipe, and jetting into the water to be treated in the aeration tank;
Repeating the second step of supplying the gas supply amount per unit time supplied into the diffuser pipe in an amount smaller than the supply amount per unit time in the first step,
An aeration method characterized by that. Using the air diffuser according to any one of claims 1 to 3,
A first step of causing the water to be treated to flow into the air diffusing pipe from the liquid introduction port while supplying the gas for diffusing to the air diffusing pipe, and jetting into the water to be treated in the aeration tank;
Repeating the second step of supplying the supply pressure of the gas supplied into the air diffuser at a lower pressure than the supply pressure in the first step,
An aeration method characterized by that.

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