JP4143453B2 - Membrane separation activated sludge treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a membrane separation activated sludge treatment apparatus that can efficiently use bubbles.
[0002]
[Prior art]
Conventionally, a membrane separation apparatus has been proposed as a solid-liquid separation (separation into activated sludge and treated water) means in a wastewater treatment apparatus utilizing the action of microorganisms (activated sludge).
[0003]
As this membrane separation apparatus, there is an apparatus installed in multiple stages using a hollow fiber membrane as a separation membrane (see, for example, Patent Document 1).
[0004]
In such an apparatus, an air supply (aeration) device is arranged at the lowermost part of the hollow fiber membranes installed in multiple stages, and the hollow fiber membranes are washed with bubbles generated by the air supply device.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-534
[Problems to be solved by the invention]
However, in Patent Document 1, since the bubbles are dissipated as they rise, and particularly, it is difficult to supply sufficient bubbles to the upper hollow fiber membrane, so that the washing efficiency is deteriorated and the hollow fiber membrane is frequently washed. There was a need.
[0007]
Although it is conceivable to prevent the dissipation of bubbles by surrounding the hollow fiber membranes installed in multiple stages with a casing, there is a problem that the casing cost is high. In addition, by using a hollow fiber membrane formed in a vertically long cylindrical shape, air bubbles can be used efficiently as in the case of multistage installation, but the hollow fiber membrane itself becomes longer and handling becomes worse, and physical strength is also increased. There is a problem of weakening.
[0008]
The present invention was made to solve the above problems, and it is an object of the present invention to provide a membrane separation activated sludge treatment apparatus that can efficiently use bubbles by preventing the dissipation of bubbles and can be manufactured at low cost. To do.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is a membrane separation activated sludge treatment apparatus for solid-liquid separation of activated sludge using a hollow fiber membrane, wherein the membrane separation apparatus is vertically arranged in the activated sludge treatment tank. These membrane separation devices are installed in multiple stages, and each includes a lower end side air diffuser and an upper end side water collecting portion opposed to each other at a predetermined interval in the vertical direction. A hollow fiber membrane bundle that is supported in the vertical direction is provided between the air portion and the water collection portion, and the air diffusion portion is formed in a hollow short cylindrical shape, and a plurality of pieces are formed on the upper surface portion thereof . By forming the air diffuser holes, the air supplied to the air diffuser is discharged between the air diffuser holes between the hollow fiber membrane bundles and floats as bubbles for cleaning the hollow fiber membranes to wash the hollow fiber membrane bundles. In addition, an air bubble recovery means is disposed between the upper membrane separator and the lower membrane separator. The bubble recovery means recovers the above-mentioned air bubbles for cleaning the hollow fiber membrane supplied to the lower membrane separator to the upper diffuser of the membrane separator, and supplies the upper air separator to the diffuser of the upper membrane separator. The present invention provides a membrane separation activated sludge treatment apparatus which is attached so as to be re-supplied.
[0010]
According to a second aspect of the present invention, the inlet opening area of the bubble recovery means is preferably set to be equal to or larger than the bubble distribution range that rises from the membrane separation device directly below the bubble recovery means.
[0012]
According to a third aspect of the present invention, the bubble recovery means preferably has a hood shape.
[0013]
As in claim 4, the configuration is coupling means for coupling the membrane separation device comprising an upper and lower and the film separator to each other are provided are preferable.
[0014]
According to a fifth aspect of the present invention, the membrane separation device is preferably configured in a cylindrical shape.
[0015]
Operation and effect of the invention
According to the present invention, before the air bubbles for washing the hollow fiber membranes supplied to the lower membrane separator are dissipated by the bubble recovery means disposed between the upper membrane separator and the lower membrane separator. Since the bubbles can be used efficiently, the amount of air supply (aeration) is reduced and the running cost is reduced.
[0016]
Moreover, since the dissipation of bubbles can be prevented without a conventional casing, the manufacturing cost is also reduced. Further, when the bubble recovery means is attached to the upper membrane separation device, the upper membrane separation device and the bubble recovery means can be handled as an integrated object, so that installation costs and maintenance costs are reduced.
[0017]
If the inlet opening area of the bubble recovery means is set to be larger than the bubble distribution range rising from the membrane separation device directly below the bubble recovery means as in claim 2, almost all of the bubbles can be recovered, so that the bubbles are more efficient. Will be available to you.
[0019]
As in claim 3, the bubble collecting means, when the hood shape, structure manufacturing cost decreases in very simple.
[0020]
If the connection means which mutually connects the membrane separation apparatus used as an upper stage and the membrane separation apparatus used as a lower stage is provided like Claim 4 , positioning of the installation height in a processing tank and taking out out of a processing tank will be carried out simultaneously It can be carried out.
[0021]
When the membrane separation device is cylindrical as in claim 5 , it is compact and easy to install in the treatment tank and easy to handle outside the treatment tank.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0023]
As shown in FIGS. 1 (a) and 1 (b), membrane separation devices 2A and 2B are installed in the activated sludge treatment tank 1 in multiple stages (two stages in this example) in the vertical direction, and from the inlet side pipe 3 The wastewater raw water supplied into the activated sludge treatment tank 1 is purified in the activated sludge treatment tank 1, and this treated water is filtered by the membrane separation devices 2A and 2B. This filtered water is provided in the outlet side pipe 4. Then, it is sucked by the pump 5 and discharged to the next process.
[0024]
As shown in detail in FIG. 2 and FIG. 3, the membrane separation devices 2A and 2B each have a short cylindrical cylindrical air diffuser 7A and 7B and a water collecting portion 8A and 8B, each having a predetermined interval L1 in the vertical direction. The air diffusers 7A and 7B and the water collectors 8A and 8B are held at a predetermined interval L1 by a support rod (not shown) extending in the vertical direction.
[0025]
Each of the air diffusers 7A and 7B is formed hollow, and a large number of air diffusers 7b are formed in the upper surface 7a [see FIG. 2 (b)], and an upper surface that avoids the air diffusers 7b. A large number of hollow fiber membranes 9a are converged in a vertically extended state between the lower surface portion 8b of the water collecting portions 8A and 8B and the lower end and the upper end thereof are fixedly supported. A hollow fiber membrane bundle 9 is provided. This hollow fiber membrane bundle 9 permeates and filters treated water, and a precision membrane (MF membrane) or an ultrafiltration membrane (UF membrane) can be suitably used.
[0026]
In the state where the hollow fiber membrane bundle 9 is fixedly supported between the air diffusers 7A and 7B and the water collecting portions 8A and 8B, the membrane separators 2A and 2B have a cylindrical shape as shown in FIG. It will be configured in shape.
[0027]
The lower surfaces of the air diffusers 7A and 7B are opened, and the air a of the air pipe 10 is supplied to the air diffuser 7A of the lower membrane separator 2A from the lower surface opening 7c. The air a supplied to the air diffuser 7A is released between the air diffuser holes 7b of the upper surface 7a between the hollow fiber membrane bundles 9 to become innumerable bubbles b, and floats as indicated by an arrow c. By doing so, the hollow fiber membrane bundle 9 is washed.
[0028]
The water collecting portions 8A and 8B are formed in a hollow shape, and the outlet pipe 4 is connected to the upper surface portion 8a, and the negative pressure is generated by the suction force of the pump 5, whereby the hollow fiber membrane bundle 9 is treated. While the water is forcibly permeated, the filtered water f is collected from the upper end of the hollow fiber membrane bundle 9 into the water collecting portions 8A and 8B and discharged from the outlet side pipe 4 to the next step.
[0029]
Immediately above the lower membrane separator 2A, an upper membrane separator 2B is disposed to face each other at a predetermined interval L2 in the vertical direction.
[0030]
A hood-like bubble recovery means 12 is fixed to the lower surface opening 7c of the air diffuser 7B of the upper membrane separator 2B. The air bubble recovery means 12 is a diffuser of the lower membrane separator 2A. The bubbles b that have been supplied and floated to the part 7A are collected and re-supplied from the lower surface opening 7c to the diffuser part 7B of the upper membrane separator 2B.
[0031]
As shown in comparison with FIG. 5, the bubble recovery means 12 has a shallow trumpet shape as shown in (a), but a cylindrical shape as shown in (b) or a deep end shape as shown in (c). As a trumpet shape, the water collecting portion 8A of the lower membrane separation device 2A may be covered.
[0032]
The area of the inlet opening 12a of the bubble recovery means 12 is set to be equal to or larger than the distribution range of the bubbles b floating from the lower membrane separation device 2A directly below.
[0033]
FIG. 9 shows that in each membrane separation device 2A, 2B, the distance L3 from the center of the hollow fiber membrane bundle 9 to the outermost surface is 75 mm, and the distance L1 between the air diffusers 7A, 7B and the water collectors 8A, 8B ( Bubble distribution measurement (void ratio) in the water collection sections 8A and 8B when air of 200 NL / min to 600 NL / min is supplied from the diffuser sections 7A and 7B with an effective total length of the hollow fiber membrane bundle 9 of 1 to 2 m. It is the graph which showed the result of measurement. In addition, white and black solid are measurement results in the X-axis direction and the Y-axis direction shown in FIG.
[0034]
As is clear from this graph, the bubbles b released from the air diffusers 7A and 7B are within a range of about 200 mm from the center of the hollow fiber membrane bundle 9 in the water collecting portions 8A and 8B.
[0035]
Accordingly, the dimension L4 of the inlet opening 12a of the bubble recovery means 12 is three times the distance L3 from the center to the outermost surface, and considering this in terms of area, the projected area (S1) of the bubble recovery means 12 on the horizontal plane is hollow. It can be seen that 9 times the projected area (S2) on the horizontal plane of the thread membrane bundle 9 is sufficient.
[0036]
As shown in FIG. 4, the upper membrane separator 2B is fixed to the casing of the activated sludge treatment tank 1, the ceiling 13 of the facility, etc., and the lower membrane separator 2A is a lower membrane separator. The water collecting part 8A of 2A and the diffuser part 7B of the upper membrane separator 2B are connected to each other by a connecting means 14 such as a chain or wire rope, and the lower membrane is separated by the upper membrane separator 2B. The predetermined distance L2 is maintained by suspending the separation device 2A.
[0037]
The operation of the membrane separation activated sludge treatment device configured as described above will be described with reference to FIG.
[0038]
When air a is supplied from the air pipe 10 to the air diffuser 7A of the lower membrane separator 2A, the air diffuser 7b discharges the air between the hollow fiber membrane bundles 9b. The air bubbles b become floating as shown by the arrow c, and the hollow fiber membrane bundle 9 of the lower membrane separator 2A is washed.
[0039]
When this bubble b reaches the water collecting section 8A of the lower membrane separation device 2A, it is once blocked by this water collecting section 8A, but as it further floats along the outer circumference of the water collecting section 8A as indicated by the arrow d. Become.
[0040]
And when this bubble b is collect | recovered by the bubble collection | recovery means 12 of the membrane separation apparatus 2B of the upper stage side, and is re-supplied to the diffuser part 7B, the hollow fiber membrane bundle 9 of the hollow fiber membrane bundle 9 will be from the diffuser hole 7b of the diffuser part 7B By being released in the meantime, the air bubbles b become countless again, and by rising as indicated by the arrow e, the hollow fiber membrane bundle 9 of the upper membrane separator 2B is washed.
[0041]
As shown in FIG. 4, when this bubble b reaches the water collecting part 8B of the upper membrane separator 2B, it is once blocked by the water collecting part 8B, but around the water collecting part 8B as indicated by the arrow g. Then, it floats further along and is discharged into the atmosphere from the surface of the treated water in the activated sludge treatment tank 1. Thus, by supplying a large amount of bubbles b into the activated sludge treatment tank 1, the inside of the activated sludge treatment tank 1 is kept in an aerobic state.
[0042]
On the other hand, since each water collection part 8A, 8B is made into the negative pressure with the suction force of the pump 5, filtration is carried out while the treated water is forcibly permeating into the hollow fiber membrane bundle 9 of each membrane separation device 2A, 2B. Water f is collected in the water collecting portions 8A and 8B from the upper end of the hollow fiber membrane bundle 9, and discharged from the outlet side pipe 4 to the next step.
[0043]
In the above embodiment, for cleaning the hollow fiber membrane bundle supplied to the lower membrane separator 2A by the bubble recovery means 12 disposed between the upper membrane separator 2B and the lower membrane separator 2A. Air bubbles b can be recovered before being dissipated and re-supplied to the membrane separator 2B on the upper side, so that the air bubbles (aeration) can be reduced and the running cost can be reduced. Becomes cheaper.
[0044]
Here, when the amount of air supply (aeration) is compared between the case where the membrane separator is installed in a single stage and bubbles are not collected and the case where the membrane separator is installed in n stages and the total amount of bubbles is collected It is expressed as the following formula.
[0045]
Air supply (aeration) amount Qa = (1-x) Q + xQ = Q in single-stage installation
Air supply (aeration) amount Qb = (1-x) Q + xQ / n = (1 + ((1-n) / n) x) Q in the case of n-stage installation
Here, x is the ratio of the amount of air released as bubbles b from the diffusers 7A and 7B out of the total air supply (aeration) amount, and Q is the air supply (aeration) required when bubbles are not recovered. ) Amount.
[0046]
If this is applied to actual conditions, x = about 0.7 is assumed. Therefore, when n = 2 (two-stage installation), Qa / Qb = 0.65, and n = 3 (three-stage installation). Then, Qb / Qa = 0.53, and it can be seen that the aeration ratio (ratio of aeration air volume flow rate and inflow sewage volume flow rate) can be easily reduced.
[0047]
Further, by providing the simple bubble recovery means 12, the dissipation of the bubbles b can be prevented even without a conventional casing, and the manufacturing cost is also reduced.
[0048]
Furthermore, since the inlet opening area of the bubble recovery means 12 is set to be equal to or greater than the bubble distribution range that rises from the lower membrane separation device 2A directly below the bubble recovery means 12, almost all of the bubbles b can be recovered. The bubbles b can be used more efficiently.
[0049]
Furthermore, since the bubble recovery means 12 is attached to the air diffuser 7B of the upper membrane separation device 2B, the upper membrane separation device 2B and the bubble recovery means 12 can be handled as an integrated object, so that installation costs and maintenance are possible. Cost is low.
[0050]
Further, since the bubble recovery means 12 has a hood shape, the structure is extremely simple and the manufacturing cost is low.
[0051]
Further, since the upper membrane separation device 2B and the lower membrane separation device 2A are connected to each other by the connecting means 14, the installation height positioning in the activated sludge treatment tank 1 and the outside of the activated sludge treatment tank 1 are performed. Can be taken out simultaneously.
[0052]
In addition, since the membrane separation devices 2A and 2B are cylindrical, it is compact and easy to install in the activated sludge treatment tank 1, and easy to handle outside the activated sludge treatment tank 1. The membrane separation devices 2A and 2B are not limited to a cylindrical shape, and may be a polygonal cylindrical shape such as a square or a hexagon.
[0053]
In the above embodiment, the bubble recovery means 12 is attached to the air diffuser 7B of the upper membrane separator 2B as shown in FIG. 6A. However, as shown in FIG. It is also possible to omit the gas portion 7B and attach only the bubble recovery means 12. In this case, a member corresponding to the upper surface portion 7a of the diffuser portion 7B may be provided.
[0054]
FIG. 7 shows a mechanism for positioning the membrane separation devices 2A and 2B in the horizontal direction. That is, two support rods 16 are set up in parallel in the activated sludge treatment tank 1, and support members having U-shaped portions 17a at the left and right positions of the water collecting portions 8A and 8B of the membrane separation devices 2A and 2B. 17 is fixed, and the U-shaped portion of the support member 17 is engaged with the two support rods 16 so as to be vertically movable.
[0055]
Thereby, horizontal positioning of each membrane separator 2A, 2B can be performed correctly.
[0056]
In the above embodiment, the upper and lower two-stage membrane separators 2A and 2B are used. However, a larger number of stages, for example, upper and lower three-stage membrane separators 2A, 2B and 2C as shown in FIG. .
[0057]
In this case, it is preferable to attach the bubble recovery means 12 to each of the middle and uppermost membrane separation devices 2B and 2C as shown in FIG.
[0058]
In the above embodiment, the upper and lower two-stage membrane separation apparatuses 2A and 2B have the same diameter and the same length, but may have different diameters and different lengths. For example, if the diameter is increased toward the upper stage, the bubbles b emitted from the lower-side membrane separation device can be efficiently recovered. In this case, the inlet opening area of the bubble recovery means 12 can be reduced.
[Brief description of the drawings]
FIG. 1 (a) is a side view of a membrane separation activated sludge treatment apparatus, and FIG. 1 (b) is a detailed side view of a two-stage membrane separation apparatus.
FIG. 2A is a perspective view of a lower membrane separator, and FIG. 2B is a perspective view of an air diffuser.
FIG. 3 is a side sectional view of an essential part of a two-stage upper and lower membrane separation apparatus.
FIG. 4 is a side view of an upper and lower two-stage membrane separator connected by a connecting means.
FIGS. 5A to 5C are side views showing an example of the shape of the bubble recovery means.
FIGS. 6A and 6B are side views showing an example of attaching the bubble recovery means.
7A and 7B are horizontal positioning mechanisms of the upper and lower two-stage membrane separation apparatus, wherein FIG. 7A is a plan view and FIG. 7B is a side view.
FIG. 8 is a side view of the upper and lower three-stage membrane separation apparatus.
FIG. 9 is a graph showing the relationship between the void ratio and the distance from the center of the hollow fiber membrane bundle.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Activated sludge treatment tank 2A-2C Membrane separator 7A, 7B Air diffuser 8A, 8B Water collecting part 9 Hollow fiber membrane bundle 9a Hollow fiber membrane 10 Air piping 12 Bubble recovery means 14 Connection means a Air b Bubble

Claims (5)

A membrane separation activated sludge treatment device for solid-liquid separation of activated sludge using a hollow fiber membrane,
In the activated sludge treatment tank, membrane separation devices are installed in multiple stages in the vertical direction,
Each of these membrane separation devices includes a lower end side air diffuser and an upper end water collector disposed opposite to each other at a predetermined interval in the vertical direction, and the air diffuser and the water collector. A hollow fiber membrane bundle that is supported in the vertical direction between the two parts,
The air diffuser is formed in a hollow short cylindrical shape, and a large number of air diffuser holes are formed on the upper surface of the air diffuser so that air supplied to the air diffuser is hollow from each air diffuser. The hollow fiber membrane bundle is washed by being released between the yarn membrane bundles and rising as air bubbles for hollow fiber membrane washing,
A bubble recovery means is arranged between the upper membrane separator and the lower membrane separator,
The bubble recovery means recovers the hollow fiber membrane cleaning bubbles supplied to the lower membrane separator to the upper air separator of the upper membrane separator, and the upper air diffuser of the membrane separator. A membrane-separated activated sludge treatment apparatus, which is attached so as to be re-supplied to the apparatus.   2. The membrane separation activated sludge treatment apparatus according to claim 1, wherein an inlet opening area of the bubble recovery unit is set to be equal to or greater than a bubble distribution range that floats from a membrane separation device directly below the bubble recovery unit.   The membrane separation activated sludge treatment apparatus according to claim 1 or 2, wherein the bubble recovery means has a hood shape.   The membrane separation activated sludge treatment apparatus according to any one of claims 1 to 3, further comprising a connecting means for mutually connecting the upper membrane separation device and the lower membrane separation device.   The membrane separation activated sludge treatment apparatus according to any one of claims 1 to 4, wherein the membrane separation device is configured in a cylindrical shape.

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