JP2008183517A - Waste water treatment equipment - Google Patents

Abstract

Provided is a wastewater treatment apparatus that can easily perform maintenance while suppressing manufacturing cost.
A suction pipe 60 connecting a hollow fiber membrane module 9 and a suction pump, and a part of the horizontal part of the suction pipe 60 is constituted by a transparent pipe 50 made of a transparent material. .
[Selection] Figure 2

Description

  The present invention relates to a wastewater treatment apparatus.

  In recent years, in wastewater treatment with activated sludge, as a technique to replace the conventional solid-liquid separation method using a sedimentation tank, a wastewater treatment device is immersed in a membrane separation tank, and sludge and treated water are separated into solid and liquid by a filtration membrane. Membrane separation activated sludge method is used.

As a wastewater treatment device used in this membrane separation activated sludge method, for example, as shown in Patent Document 1, a plurality of filtration membrane devices provided with separation membranes are provided in a membrane separation tank, and treated water is supplied to each filtration membrane device. The take-out pipe to be taken out is connected. The filtered treated water is sucked through a suction pump connected to the take-out pipe.
Moreover, in such a wastewater treatment apparatus, in order to perform maintenance easily, an apparatus in which a transparent tube portion through which an internal fluid can be seen through is provided in a water exposed portion of the extraction tube.

According to the waste water treatment apparatus described above, since the color, fluid, etc. of the fluid can be discriminated by visually observing the internal fluid from the transparent tube portion, only the internal fluid is visually observed from the transparent tube portion. In this operation, it is possible to determine the abnormality of the filtration membrane device. Therefore, it is possible to quickly determine which filtration membrane device needs maintenance, and maintenance becomes easy.
Japanese Patent Laid-Open No. 08-132039

  By the way, in the above-described wastewater treatment apparatus, the suction pump is used to take out the internal fluid, so that air is mixed in the extraction pipe when the suction pump is started. The mixture of air leads to a load on starting the suction pump, and there is a problem that it is difficult to perform a stable operation.

  In addition, since a transparent tube portion is provided for each filtration membrane device, the manufacturing cost increases, and when a large number of filtration membrane devices are provided, maintenance of all transparent tube portions is performed. There is a problem that it is difficult.

  Then, this invention is made | formed in view of the above-mentioned subject, and provides the waste-water-treatment apparatus which can perform a maintenance easily, suppressing manufacturing cost.

In order to solve the above problems, the invention described in claim 1 includes a membrane separation tank in which water to be treated is accommodated, and a number of solid-liquid separations that are immersed in the inside of the membrane separation tank. A membrane separation device in which a plurality of hollow fiber membrane elements made of porous hollow fiber membranes are arranged, a diffuser generator disposed below the membrane separation device, and water to be treated solid-liquid separated by the membrane separation device In the wastewater treatment apparatus including the suction pump, the uppermost part of the suction pipe connecting the membrane separation device and the suction pump, and a part of the horizontal part is configured by a transparent pipe made of a transparent material. It is characterized by.
By configuring in this way, the suction pump is started at the initial operation or after the chemical washing because the transparent pipe is arranged at the uppermost part where the air bubbles are easily accumulated in the suction pipe. Sometimes, it is possible to reliably grasp the state of bubbles accumulated in the suction pipe.

The invention described in claim 2 is characterized in that a plurality of the membrane separation devices are arranged inside the membrane separation tank, and the transparent piping is provided corresponding to the suction piping of each membrane separation device. .
By comprising in this way, since the transparent piping is provided corresponding to the suction piping of each membrane separator, the condition of the to-be-processed water in a suction piping can be grasped | ascertained easily.

The invention described in claim 3 is characterized in that the transparent pipe is detachably provided.
By comprising in this way, a transparent piping can be easily removed at the time of replacement | exchange, chemical washing, etc. of transparent piping.

According to the first aspect of the present invention, since the state of bubbles accumulated in the suction pipe can be surely grasped at the time of initial operation or after starting of the suction pump after chemical washing, suction is performed accordingly. The pump can be operated with a reduced load.
According to the second aspect of the present invention, the manufacturing cost can be reduced and the maintenance can be easily performed as compared with the conventional configuration in which the transparent pipe is provided for each hollow fiber membrane element.
According to the invention described in claim 3, since the transparent pipe can be easily removed at the time of replacement of the transparent pipe, chemical washing, or the like, maintenance can be easily performed.

Next, embodiments of the present invention will be described with reference to the drawings.
In this embodiment, the wastewater treatment apparatus of the present invention is applied to a membrane separation activated sludge treatment apparatus that purifies wastewater such as industrial wastewater and domestic wastewater (hereinafter referred to as raw water).
As shown in FIG. 1, a screen 1 is disposed at the inflow end of the membrane separation activated sludge treatment apparatus. This screen 1 removes a relatively large solid content from raw water. A raw water adjustment tank 2 is provided on the outflow side of the screen 1. The raw water adjustment tank 2 is for containing raw water from which a relatively large solid content has been removed by the screen 1, and a liquid level measuring instrument (not shown) is provided on the liquid level.

  An oxygen-free tank 3 is provided on the outflow side of the raw water adjustment tank 2. The anoxic tank 3 is a tank that performs denitrification while maintaining the raw water in an anaerobic state, and the raw water is intermittently supplied from the raw water adjustment tank 2 by the first liquid feed pump P1. An aeration tank (membrane separation tank) 4 is provided on the outflow side of the anaerobic tank 3. The aeration tank 4 accommodates raw water overflowing from the anoxic tank 3, and makes the raw water and air contact to sufficiently supply oxygen in the air, thereby promoting the decomposition process of aerobic microorganisms. is there. In the aeration tank 4, a membrane filtration unit 5 (waste water treatment device) is disposed so as to be immersed. This membrane filtration unit 5 separates the raw water accommodated in the aeration tank 4 into activated sludge and treated water.

  A sludge storage tank 7 is provided on the outflow side of the aeration tank 4 via a third liquid feed pump P3. In the sludge storage tank 7, the solid content (suspension material) of the sludge grown by aeration in the aeration tank 4 is precipitated by its own weight, and the excess sludge is stored.

  A circulation port 6 is provided at the bottom of the aeration tank 4. In this circulation port 6, the anoxic tank 3 and the aeration tank 4 communicate with each other, and a part of the sludge is returned to the anoxic tank 3 by the second liquid feed pump P2. That is, the anoxic tank 3 and the aeration tank 4 are configured to be circulated.

Next, the membrane filtration unit 5 will be described.
As shown in FIG. 2, the membrane filtration unit 5 includes an aeration generator 15 in the lower part. The air diffuser 15 includes a rectangular casing 24 that is open at the top and bottom, and columns 24a that extend downward are formed at the lower ends of the four corners thereof.

  As shown in FIG. 3, an air introduction pipe 16 is provided on the outer wall of the casing 24. The air introduction pipe 16 supplies the air supplied from the aeration blower B provided outside the aeration tank 4 through the main pipe 18 into the casing 24 of the diffuser generator 15 (see FIG. 1). ).

  The air introduction pipe 16 communicates with the air supply header 30 with the casing 24 interposed therebetween. The air supply header 30 is a small chamber provided along the inner wall of the casing 24, and a plurality of air diffusers 17 are connected to the inner wall 30 a perpendicular to the air supply header 30. The air diffuser 17 is composed of a rubber tube with a slit or the like, and one end is connected to the air supply header 30 and the other end is closed. The air diffuser 17 discharges the air supplied from the aeration blower B upward.

  As shown in FIG. 2, the membrane filtration unit 5 includes a frame 31 extending upward from the four corners of the air diffuser 15, and the frame 31 includes a hollow fiber membrane module 9 (membrane separation device). Is supported. This hollow fiber membrane module 9 has a plurality of (for example, 20) hollow fiber membrane elements 10 arranged in parallel.

  The hollow fiber membrane element 10 includes a lower frame 13, and a pair of vertical rods 14 are provided upward at both ends thereof. An upper frame 12 is provided at the upper end of the vertical rod 14. A passage (not shown) is formed in the upper frame 12 along the longitudinal direction, and this passage is formed at the end of the upper frame 12 as a filtrate outlet 12a. An L-shaped joint 12b that is bent upward is connected to the filtrate outlet 12a with a sealing material (not shown) interposed therebetween.

  In the hollow fiber membrane element 10, a large number of hollow fiber membranes 10 a are arranged along the vertical rod 14. The hollow fiber membrane 10a is formed to be hollow in the length direction, and a filtration hole (hole diameter is 0.4 μm, for example) not shown is formed around the hollow fiber membrane 10a. The hollow fiber membrane 10a is made of PVDF (polyvinylidene fluoride) or the like, and filters raw water in the aeration tank 4 into sludge and treated water.

The lower end of the hollow fiber membrane 10a is fixed and supported on the lower frame 13 by the potting material 11a, and the upper end is communicated and supported by the filtered water outlet 12a formed in the passage in the upper frame 12 by the potting material 11a. A hollow fiber membrane sheet 11 in which a number of hollow fiber membranes 10a are arranged is configured. Here, the effective membrane area of the hollow fiber membrane element 10 per hollow fiber membrane element 10 is 25 m ² . A casing 20 is provided so as to cover the hollow fiber membrane module 9 in which a plurality of hollow fiber membrane elements 10 are arranged.

  A water collection header 21 is provided on the upper portion of the frame 31 along the arrangement direction of the hollow fiber membrane elements 10. The water collecting header 21 is formed with a plurality of water collecting ports 21a along the longitudinal direction. An L-shaped joint 21b bent downward is connected to the water collecting port 21a with a sealing material (not shown) interposed therebetween. ing. The L-shaped joint 21b and the L-shaped joint 12b connected to the filtered water outlet 12a of the hollow fiber membrane element 10 are connected to each other, and the high-quality treated water filtered by the hollow fiber membrane 10a is supplied to the water collection header 21. It is configured to allow water to pass.

  A water inlet 21 c is provided on the upper surface of the water collection header 21. A pipe 22 a is connected to the water inlet 21 c upward, and the main pipe 22 is connected to the outflow side of the pipe 22 a via an elbow pipe 54. The treated water filtered by the membrane filtration unit 5 immersed in the aeration tank 4 flows inside the pipe 22 a, the elbow pipe 54, and the main pipe 22. That is, the suction pipe 60 that connects the membrane filtration unit 5 and the treated water tank 8 to be described later is configured to allow water to flow through the pipe 22a, the elbow pipe 54, and the main pipe 22.

  Here, the main pipe 22 is the uppermost part of the suction pipe 60 through which the treated water flows, and is arranged in the horizontal direction with the level of the raw water stored in the aeration tank 4. A transparent pipe 50 is provided in a part of the main pipe 22. The transparent pipe 50 is made of a transparent material such as resin, and is configured so that the treated water filtered by the membrane filtration unit 5 can be visually recognized.

  As shown in FIG. 4, the transparent pipe 50 includes flanges 51a and 51b at both ends. The flange 51a at one end of the transparent pipe 50 is fixed to the flange 25a of the main pipe 22 by a plurality of bolts 53 with a seal material (not shown) interposed therebetween, and the flange 51b at the other end is fixed to the main pipe with a seal material (not shown) interposed therebetween. 22 is fixed to the flange 25b by a plurality of bolts 53. That is, the flanges 51 a and 51 b of the transparent pipe 50 are detachably attached to the main pipe 22 by the bolts 53.

  A suction pump Pv is provided on the outflow side of the main pipe 22, and a treated water tank 8 is provided on the outflow side of the suction pump Pv (see FIG. 1). This treated water tank 8 contains the treated water of high quality that has been filtered by the hollow fiber membrane element 10 of the aeration tank 4.

Next, the operation will be described.
First, a relatively large solid content is removed from the raw water by the screen 1 and introduced into the raw water adjustment tank 2. Here, the liquid level is measured by a liquid level measuring device, and the first liquid feed pump P1 is intermittently operated to adjust the liquid level height of the raw water adjustment tank 2 within a predetermined range. The raw water sent by the first liquid feeding pump P1 is caused to flow into the adjacent aeration tank 4 using the raw water overflowing from the anoxic tank 3.

  Subsequently, the raw water is biochemically purified by activated sludge in the anoxic tank 3 and the aeration tank 4. Nitrogen is removed by a so-called nitrification denitrification reaction by circulating sludge between the anoxic tank 3 and the aeration tank 4. The organic matter converted into BOD (biochemical oxygen demand) is aerobic by the air discharged from the diffuser generator 15 of the membrane filtration unit 5 which is mainly an aeration apparatus disposed in the aeration tank 4. To be disassembled. The removal of phosphorus is carried out by being incorporated into the body of the microorganism as polyphosphoric acid by the action of microorganisms (phosphorus-accumulating bacteria) in the sludge. This microorganism takes up phosphorus in an aerobic state and releases phosphorus stored in the body in an anaerobic state. When repeatedly exposed to anaerobic and aerobic conditions, phosphorus-accumulating bacteria absorb more phosphorus in an aerobic state than the amount of phosphorus released in the anaerobic state.

  Some of the nitrogen compounds such as biological excrement and carcasses are assimilated into plants and bacteria as fertilizers. Some of these nitrogen compounds are oxidized to nitrous acid and nitric acid by autotrophic ammonia oxidizing bacteria and independent nitrite oxidizing bacteria under aerobic conditions with a lot of oxygen. On the other hand, under anaerobic conditions without oxygen, microorganisms called denitrifying bacteria produce nitrous acid from nitric acid instead of oxygen, and further reduce to dinitrogen monoxide and nitrogen gas. This reduction reaction is referred to as the nitrification denitrification reaction.

  The circulation of sludge between the anaerobic tank 3 and the aeration tank 4 is not necessarily limited from which tank the liquid is fed using the pump, but normally the aeration tank using the second liquid feeding pump P2. The liquid is fed from 4 to the anaerobic tank 3 and is allowed to flow from the anoxic tank 3 into the aeration tank 4 by overflow. In the present embodiment, the DOC at the site where the circulating fluid enters the anaerobic tank 3 from the aeration tank 4 is 0.2 mg / L or less, and / or the DOC at the site where the circulating liquid is taken out from the aeration tank 4 is set to 0.00. By setting it to 5 mg / L or less, the inflow of dissolved oxygen into the anoxic tank 3 is suppressed, and the anaerobic degree in the anoxic tank 3 is sufficiently maintained, thereby promoting the release of phosphorus.

  If dissolved oxygen, nitrate ions, and nitrite ions are not substantially present in the anoxic tank 3, the organic matter is decomposed anaerobically, and at this time, polyphosphoric acid accumulated in the bacteria is released out of the cells as phosphoric acid. . In this embodiment, the DOC in the part where the circulating sludge is returned from the aeration tank 4 to the anaerobic tank 3 is preferably 0.2 mg / L or less, and if it is 1 mg / L or less, the phosphorus removability is more stable. Furthermore, 0.05 mg / L or less is preferable because of further stabilization. In addition, the measurement of DOC can be measured using the normal DO meter by the diaphragm electrode method.

  In order to set the DOC of the part where the circulating fluid (sludge) is taken out from the aeration tank 4 to 0.5 mg / L or less, the part where the sludge is taken out from the aeration tank 4 to the anoxic tank 3 is made a sludge retention part. Is preferred. The sludge retention part means a part that is less susceptible to sludge flow due to aeration. For example, if a space is provided between the membrane filtration unit 5 and the bottom of the aeration tank 4, the sludge existing in the lower part of the membrane filtration unit 5 is not well agitated, and thus becomes a retention part.

  Therefore, as shown in FIG. 1, by taking out sludge from below the position of the membrane filtration unit 5, the DOC of the part where the circulating fluid (sludge) is taken out from the aeration tank 4 should be 0.5 mg / L or less. Can do. When a plurality of membrane filtration units 5 are arranged in parallel in the aeration tank 4, the part from which the circulating liquid (sludge) is taken out is located below the aeration tank 4. Further, the distance from the membrane filtration unit 5 to the site where the sludge is taken out is preferably 20 cm or more downward, and more preferably 30 cm or more.

  The flow of sludge in the aeration tank 4 is mainly due to the rise of air discharged from the air diffuser 17 in the aeration part by the membrane filtration unit 5, and the sludge descends in the part that is not aerated. This stirs the whole. At this time, if the oxygen utilization rate (rr) of the sludge in the aeration tank 4 is kept high, oxygen is rapidly consumed in the part where the aeration is not performed, so that the dissolved oxygen becomes low in the aeration tank 4. It becomes easy to form a site. Here, the oxygen utilization rate (rr) of sludge in the aeration tank 4 refers to the oxygen utilization rate of sludge taken from the aerated portion of the aeration tank 4, and the measurement method is a sewer test method (1997). Year, according to Japan Sewerage Association).

  The raw water in the aeration tank 4 is filtered by the hollow fiber membrane 10 a of the membrane filtration unit 5. Specifically, air is discharged upward from the air diffuser 17 of the air diffuser 15, and the hollow fiber membrane 10a is vibrated by this air to perform scrubbing. And it filters, preventing a foreign material adhering to the hollow fiber membrane 10a. Thereby, the raw water is solid-liquid separated into sludge and treated water.

  The treated water filtered by the membrane filtration unit 5 is sucked by intermittently operating the suction pump Pv, and is carried out from the water inlet 21c of the water collection header 21 to the treated water tank 8 through the suction pipe 60.

  Here, air remains in the suction pipe 60 at the initial operation of the suction pump Pv or at the start of operation such as after chemical washing. When the treated water is sucked, the air remaining in the suction pipe 60 becomes bubbles and rises in the pipe 22a and stays in the main pipe 22 as an air pool (for example, F in FIG. 4). As a result, when the normal operation is performed as it is, the load on the suction pump Pv is increased, and it is difficult to perform a stable operation.

In view of this, since the transparent pipe 50 is provided in a part of the main pipe 22 in which air bubbles in the suction pipe 60 tend to stay as an air pool, the presence or absence of an air pool can be checked by visually checking the inside of the transparent pipe 50. It is possible to grasp with certainty. Eliminating air pools, for example, by temporarily increasing the amount of treated water sucked by the suction pump Pv, using a combination of other pumps, or installing an ejector, increases the flux (flux) in the main pipe 22 more than normal operating conditions. Is possible. It is also possible to forcibly fill the main pipe 22 with water or attach an air vent valve. And it can transfer to a normal driving | operation after eliminating an air pool.
On the other hand, the contaminants that precipitate at the bottom of the aeration tank 4 are sucked by the third liquid feeding pump P3 and carried out to the sludge storage tank 7.

  Further, when it is necessary to replace the transparent pipe 50 due to damage, chemical washing or the like, it can be easily removed by loosening the bolts 53. In addition, a valve may be provided adjacent to the flanges 25a and 25b of the main pipe 22, and the transparent pipe 50 may be connected via each valve. In this case, the work is facilitated by closing the valve when the transparent pipe 50 is replaced.

  According to the present embodiment, the transparent pipe 50 is provided on the uppermost part of the main pipe 22 arranged in the horizontal direction at the uppermost portion where bubbles remaining in the suction pipe 60 are easily collected. The air accumulation in 60 can be grasped reliably. Therefore, at the time of initial operation or after the start of operation of the suction pump Pv after chemical washing or the like, it is possible to perform an operation in which the load on the suction pump Pv is reduced in accordance with the air accumulation, and then shift to a normal operation.

A transparent pipe 50 is provided in the main pipe 22 of the suction pipe 60 that connects the water collection header 21 of the membrane filtration unit 5 and the suction pump Pv. Therefore, compared to the conventional configuration in which a transparent pipe is provided for each hollow fiber membrane element, the manufacturing cost can be reduced, and the treated water can be managed for each membrane filtration unit 5, so that maintenance is easy. Can be done.
Furthermore, since the transparent pipe 50 is detachably provided to the main pipe 22, it can be easily removed at the time of replacement of the transparent pipe 50 or chemical washing.

Next, a second embodiment of the present invention will be described based on FIG. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
As shown in FIG. 5, the second embodiment of the present invention is different from the first embodiment in that a plurality (for example, two) of membrane filtration units 5 are immersed in the aeration 4 tank. . Each membrane filtration unit 5 is provided with a transparent pipe 50 corresponding to the main pipe 22 of each suction pipe 60. The outflow side of each suction pipe 60 is connected to the collective pipe 122 via an elbow pipe 154a and a T-shaped pipe 154b, and the suction pump Pv is connected to the outflow side of the collective pipe 122.

  According to the present embodiment, the same effects as in the first embodiment can be obtained, and even when a plurality of membrane filtration units 5 are arranged in the aeration tank 4, the main piping 22 of each membrane filtration unit 5 is transparent. Since the pipe 50 is provided, the treated water can be managed for each membrane filtration unit 5. Therefore, compared with the structure which provides a transparent piping for every hollow fiber membrane element conventionally, while being able to hold down manufacturing cost, maintenance can be performed easily.

It should be noted that the technical scope of the present invention is not limited to the above-described embodiments, and includes those in which various modifications are made to the above-described embodiments without departing from the spirit of the present invention. For example, the radix of the membrane filtration unit can be appropriately changed according to the size of the aeration tank.
The size of the membrane filtration unit, the number of hollow fiber membrane elements per unit, and the like can be variously changed according to the application. For example, in terms of the number of hollow fiber membrane elements, it can be changed to 40, 60, etc. according to the processing amount, or the material of the porous hollow fiber membrane is cellulose, polyolefin, polysulfone, polyvinyl alcohol. Conventionally known materials such as those based on polymethyl alcohol, polymethyl methacrylate, and polyfluorinated ethylene can be applied.

It is a schematic block diagram of the membrane separation activated sludge processing apparatus in embodiment of this invention. It is a perspective view shown partially broken of the membrane filtration unit in the first embodiment of the present invention. It is a perspective view of the aeration generation apparatus of a membrane filtration unit. It is sectional drawing which follows the AA line of FIG. It is a perspective view of the membrane filtration unit in 2nd Embodiment of this invention.

Explanation of symbols

4 Aeration tank (membrane separation tank)
5 Membrane filtration unit (waste water treatment equipment)
9 Hollow fiber membrane module (membrane separator)
10 Hollow fiber membrane element 10a Hollow fiber membrane (porous hollow fiber membrane)
15 Air diffuser 22 Main piping (suction piping)
22a Piping (suction piping)
50 Transparent piping 60 Suction piping Pv Suction pump

Claims (3)

A plurality of hollow fiber membrane elements comprising a membrane separation tank containing treated water and a number of porous hollow fiber membranes arranged in a state immersed in the membrane separation tank and solid-liquid separated from the treated water A wastewater treatment apparatus comprising: a membrane separation apparatus; a diffuser generator disposed below the membrane separation apparatus; and a suction pump for obtaining treated water that has been solid-liquid separated by the membrane separation apparatus.
A wastewater treatment apparatus, characterized in that it is the uppermost part of a suction pipe connecting the membrane separator and the suction pump, and a part of the horizontal part thereof is constituted by a transparent pipe made of a transparent material.   2. The wastewater treatment apparatus according to claim 1, wherein a plurality of the membrane separation devices are arranged inside the membrane separation tank, and the transparent piping is provided corresponding to the suction piping of each membrane separation device.   The wastewater treatment apparatus according to claim 1 or 2, wherein the transparent pipe is detachably provided.

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