JPH11347377A - Solid-liquid separation apparatus and washing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid-liquid separation apparatus capable of efficiently removing the solid such as sludge or the like bonded to and deposited on a membrane surface by a simple apparatus constitution without damaging membranes and a method for washing the same. SOLUTION: Washing nozzles 10 ejecting washing water in the direction almost parallel to the surface of the separation membrane (separation unit 3) immersed in a solid-liquid separation tank 2 are provided in the vicinity of the separation membrane and raw water in the solid-liquid separation tank 2 is discharged to be exposed to the separation membrane and washing water using a part of treated water is ejected from the washing nozzles 10 to wash a membrane surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-liquid separation device and a method for cleaning the same, and more particularly, to a nonwoven fabric, a microfiltration membrane,
The present invention relates to cleaning of a separation membrane in the form of a flat membrane such as an ultrafiltration membrane or a solid-liquid separation apparatus that performs solid-liquid separation using a fine eye screen.

[0002]

2. Description of the Related Art In a final step of various water treatments, a solid-liquid separation device using a separation membrane is used as a means for separating solids such as suspended solids and activated sludge in raw water. In this solid-liquid separation device, a separation membrane is immersed in raw water in a solid-liquid separation tank, and only the liquid (treated water) is permeated by reducing the pressure inside the membrane to perform solid-liquid separation.

[0003] On the other hand, solids in raw water become attached to the surface of the separation membrane by the solid-liquid separation operation. Therefore, the solids gradually accumulate as the operation proceeds, and the separation ability of the separation membrane is reduced. become. For this reason, conventionally, water or air is caused to flow backward from the suction side of the separation membrane, high-pressure water is sprayed on the membrane surface to peel off physically deposited solids, or chemically washed with a chemical solution. ing.

[0004]

However, when a flat membrane type is used as the separation membrane, the membrane may expand and be damaged when washing by backflow. When high-pressure water is sprayed, the separation membrane must be pulled up from the solid-liquid separation tank and performed on each separation membrane, which is not only very time-consuming but also requires cleaning. The time was long, and the membrane was sometimes damaged by a large impact due to the collision of high-pressure water. On the other hand, cleaning with a chemical solution must be performed at appropriate intervals in order to remove not only solid substances adhered to the film surface but also scales.
In the conventional method, the separation membrane has to be taken out of the solid-liquid separation tank and transferred to the chemical tank, which is troublesome, there are problems such as the cost of the chemical solution, and the life of the separation membrane is adversely affected. Chemical cleaning cannot be performed.

Accordingly, the present invention provides a solid-liquid separation apparatus capable of efficiently removing solid matter such as sludge deposited on the membrane surface with a simple apparatus configuration without damaging the membrane, and a method for cleaning the same. It is intended to be.

[0006]

In order to achieve the above object, a solid-liquid separation device according to the present invention is a solid-liquid separation device for performing solid-liquid separation using a separation membrane immersed in a solid-liquid separation tank.
A cleaning nozzle for ejecting cleaning water in a direction substantially parallel to the surface of the separation membrane is provided near the separation membrane.

In order to achieve the above object, a method for cleaning a solid-liquid separation device according to the present invention is a method for cleaning a solid-liquid separation device in which solid-liquid separation is performed by a separation membrane immersed in a solid-liquid separation tank. After discharging the raw water in the solid-liquid separation tank to expose the separation membrane, a washing nozzle provided in the vicinity of the separation membrane,
The membrane surface is washed by jetting a part of the treated water subjected to the solid-liquid separation treatment by the solid-liquid separation device as washing water in a direction substantially parallel to the membrane surface. A method and a method in which the separation membrane is immersed in raw water, and a diffused cleaning by diffusing air from a diffuser installed below the separation membrane is selected according to the state of the separation membrane. I have.

[0008]

1 and 2 show an embodiment of the present invention. FIG. 1 is a schematic diagram of a solid-liquid separation device, and FIG. 2 is a schematic plan view. This solid-liquid separation device 1 has a separation membrane unit 3 installed inside a solid-liquid separation tank 2,
In the solid-liquid separation tank 2, a raw water inflow pipe 4, a drain pipe 5, and an overflow pipe 6 are provided at predetermined positions, respectively.
A diffuser 7 is provided at the bottom of the tank below the separation membrane unit 3. The separation membrane unit 3 is connected to a treated water suction pipe 9 leading to a treated water tank 8. On both sides of the upper part of the unit 3, washing nozzles 10 for ejecting washing water in a direction substantially parallel to the surface of the separation membrane (membrane module) 3a forming the separation membrane unit 3 correspond to each membrane module 3a. It is provided.

First, in a normal solid-liquid separation operation, the valve 5V of the drain pipe 5 is closed and the valve 4V of the raw water inflow pipe 4 is opened.
This is performed by operating the pump 9P of the treated water suction pipe 9. As a result, the water in the raw water flowing into the solid-liquid separation tank 2 through the raw water inflow pipe 4 from the preceding treatment tank and the solid matter such as sludge are separated by the separation membrane unit 3, and only water is separated from the separation membrane unit. 3 and is sent to the treated water tank 8, and a surplus amount of treated water flows out of the outflow pipe 11 while a predetermined amount of treated water is held in the treated water tank 8. Excess raw water in the solid-liquid separation tank 2 flows out together with sludge from the overflow pipe 6 and is returned to the preceding treatment tank.

When a certain amount of solid matter adheres and deposits on the film surface, or periodically, for example, every several hours,
The air is diffused by operating the blower 7B of the air diffuser 7 to perform cleaning by collision of bubbles on the film surface and upward flow by an air lift effect, that is, film cleaning by so-called air scrubbing. Thereby, the growth of the cake layer made of solid matter such as activated sludge deposited on the membrane surface can be suppressed, and the solid-liquid separation operation can be continuously performed. The air diffuser 7
In the case of performing aerobic treatment according to processing conditions other than solid-liquid separation in the solid-liquid separation tank 2, for example, air diffusion may be performed continuously.

The membrane cleaning by air scrubbing is as follows.
Although a certain effect can be obtained, it is difficult to uniformly clean the film surface, and the pressure difference between the films gradually increases.
Therefore, when the transmembrane pressure rises to a predetermined value or more due to continuation of the operation, or periodically, for example, once a day,
Sprinkle cleaning is performed by the cleaning nozzle 10. In the sprinkling cleaning, first, the valve 4V is closed to stop the flow of the raw water, and the pump 9P is stopped to stop the suction of the treated water. Then, the valve 5V is opened to drain the raw water in the tank from the drain pipe 5. Discharge. When the amount of water in the tank falls below a predetermined water level, the pump 12P of the washing pipe 12 connected to the washing nozzle 10 is operated to supply the treated water in the treated water tank 8 to the washing nozzle 10. Thereby, the cake layer on the membrane surface is washed away by the washing water. Further, the washed water is discharged from the drain pipe 5 at the bottom of the tank together with sludge and the like separated from the membrane surface, and returned to the treatment tank in the preceding stage.

At this time, since the jetting direction of the washing water from the washing nozzle 10 is set to a direction substantially parallel to the surface of the membrane module 3a, the washing water does not strongly strike the membrane surface. Even if a certain amount of high-pressure washing water is used, there is almost no damage to the membrane module 3a. Therefore, by using high-pressure water in a range that does not damage the membrane module 3a, biological slime on the membrane surface can be removed to some extent. Furthermore, since the solid-liquid separation tank 2 is drained to expose the membrane module 3a to the gas phase, the momentum of the washing water can directly act on the membrane surface, and the washing efficiency is excellent.

Further, since the membrane surface can be washed only by operating a valve or a pump while the separation membrane unit 3 is installed in the solid-liquid separation tank 2, the washing is performed automatically and in a short time. And even if sludge or the like scatters during washing, it does not scatter outside. And as washing water,
Since the treated water stored in the treated water tank 8, that is, the treated water subjected to the solid-liquid separation treatment in the solid-liquid separation device 1 is used, the clogging of the washing nozzle 10 hardly occurs and the maintenance and management are easy. It is.

Further, in the case of water treatment by the activated sludge method, since the formation of a cake layer on the membrane surface is extremely fast, the above-mentioned membrane cleaning by air scrubbing and the above-described water spray cleaning from the cleaning nozzle 10 are used in combination. , Membrane module status,
By selecting which type of washing is performed in accordance with the state of the transmembrane pressure, the operation stop time in the solid-liquid separation device 1 can be minimized, and the efficiency decreases due to an increase in the transmembrane pressure. Can be suppressed.

Further, by measuring the transmembrane pressure in a state where the cake layer does not exist on the membrane surface immediately after the water-washing, the rise of the transmembrane pressure due to the generation of scale can be accurately grasped. Therefore, it is possible to accurately determine the timing of performing the chemical cleaning, reduce the cost required for the chemical cleaning, and extend the life of the membrane module 3a.

In the worst case, the space between the membrane modules 3a may be closed due to the growth of the cake layer on the surface. Therefore, it has been necessary to provide a sufficient space in the past. By performing the water washing as described above at an appropriate interval, the cake layer can be reliably removed, and the washing water is jetted in a direction substantially parallel to the membrane surface, so that the interval between the membrane modules 3a is also reduced. Since the width can be reduced, the capacity of the membrane unit 3 can be reduced. In addition, even if the generation rate of the cake layer is high, the cake layer can be easily and automatically removed by sprinkling and washing, so that the suction water amount in the membrane unit 3 can be set higher without regard to the generation rate of the cake layer. It becomes possible. Therefore, the size of the entire membrane separation device can be reduced by downsizing the membrane unit 3 and increasing the amount of suction water,
The construction cost of membrane processing equipment can be reduced.

Further, when performing the chemical cleaning, it is necessary to perform water cleaning before and after the cleaning. However, since the same effect can be obtained by the above-described sprinkling cleaning, it is not necessary to perform special water cleaning, and the chemical cleaning is not required. Time and labor required for In addition, the solid-liquid separation tank 2 can be used as it is as a chemical liquid cleaning tank, and the amount of the chemical liquid can be reduced by downsizing the membrane unit 3 described above, so that the chemical liquid cleaning can be performed very easily and at low cost. Becomes possible.

When the water washing is completed and the operation shifts to the ordinary solid-liquid separation operation, the valve 5V of the drain pipe 5 is closed, the valve 4V of the raw water inflow pipe 4 is opened, and the solid-liquid separation tank is opened. The pump 9P of the treated water suction pipe 9 may be operated when the water level in 2 reaches the set water level.

The installation position and the number of cleaning nozzles 10 for each membrane module 3a can be arbitrarily selected according to the size of the membrane module 3a and the like, and can be installed immediately above, sideways or below. However, in consideration of pulling up of the separation membrane unit 3 at the time of maintenance or the like and scattering of washing water, both upper sides of the separation membrane unit 3 are optimal. Further, the shape of the cleaning nozzle 10 is arbitrary, but a type in which the cleaning water is jetted in a fan shape is optimal. Further, since a large amount of the cake layer adheres to the treated water suction pipe 9 side of the separation membrane unit 3, it is preferable that the washing water be ejected from the treated water suction pipe 9 side or the ejection amount is increased. Also, as shown by the broken line in FIG. 1, by providing the side plate 13 around the separation membrane unit 3, the swirling flow at the time of membrane cleaning by air scrubbing can be promoted, and the cleaning efficiency can be improved. .

FIG. 3 is a system diagram showing an example in which the solid-liquid separation device of the present invention is applied to a sewage treatment device using an activated sludge method. In the following description, the same components as those in the solid-liquid separation device of the above embodiment will be denoted by the same reference numerals, and detailed description will be omitted.

This sewage treatment apparatus is provided with a sedimentation basin 21, a screen 22, a flow control tank 23, a reaction tank 24, a solid-liquid separator 1, and a treated water tank 8 in this order from the sewage inflow side. That is, the inflowing sewage flows into the reaction tank 24 through the sedimentation basin 21, the screen 22, and the flow rate adjusting tank 23, and is treated in an anaerobic state. Then, it is sucked by the pump 4A and solidified from the raw water inflow pipe 4. It flows into the liquid separation tank 2. In this solid-liquid separation tank 2, in addition to the above-mentioned solid-liquid separation,
Aerobic treatment is performed by continuous aeration from the diffuser 7, and an effective denitrification treatment can be performed by returning a part of the raw water from the overflow pipe 6 to the reaction tank 24 as a nitrification liquid. it can. Further, since the water after the watering and washing is returned to the reaction tank 24 via the drain pipe 5 together with the sludge,
The activated sludge concentration can be increased, and the treatment efficiency can be improved and the treatment time can be shortened.

FIG. 4 is a system diagram showing an example in which the solid-liquid separation device of the present invention is applied to a sewage recycling facility, in which the solid-liquid separation device 1 is installed downstream of the final sedimentation basin 31. The final sedimentation basin 31 is connected to the solid-liquid separation tank 2 through the raw water inflow pipe 4.
The water flowing through the treated water channel 32 is pumped up by the pump 4P and flows in. In this case, the water flowing through the treatment water channel 32 is water that has been treated in the final sedimentation basin 31 and has a small solid content and extremely slow growth of the cake layer. It is not necessary to perform the cleaning, and only the sprinkling washing is sufficient. Therefore, it is not necessary to provide the air diffuser 7. Further, since it is not necessary to return a part of the inflow water as nitrification liquid, the overflow pipe 6
It is not necessary to provide.

The water after watering and washing containing solid matter is drained into a drain pipe 5
By returning to the inflow part 33 of the final sedimentation basin 31 or the aeration tank provided in the stage preceding the final sedimentation basin 31, aeration and sedimentation can be performed again. There is no need to add a processing device.

As described above, the present invention can be applied to the solid-liquid separation in the first and second stages of various water treatment facilities.
It is possible to improve not only the efficiency of solid-liquid separation but also the efficiency of the entire water treatment facility. As the separation membrane, various types such as the above-mentioned nonwoven fabric, microfiltration membrane, ultrafiltration membrane, fine mesh screen, etc. are appropriately selected according to the size and amount of solids contained in raw water, the purpose of treatment, and the like. Can be used.

[0025]

As described above, according to the present invention,
The separation membrane (membrane module) can be washed very easily and efficiently, and the treated water after solid separation is used as washing water, so that clogging of the washing nozzle hardly occurs and maintenance is easy. . Further, since the washing water is jetted substantially parallel to the membrane surface, the interval between the membranes can be narrowed, and the size of the separation membrane unit can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a solid-liquid separation device showing one embodiment of the present invention.

FIG. 2 is a schematic plan view similarly.

FIG. 3 is a system diagram showing an example in which the solid-liquid separation device of the present invention is applied to a sewage treatment device using an activated sludge method.

FIG. 4 is a system diagram showing an example in which the solid-liquid separation device of the present invention is applied to a sewage recycling facility.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Solid-liquid separation apparatus, 2 ... Solid-liquid separation tank, 3 ... Separation membrane unit, 4 ... Raw water inflow pipe, 5 ... Drain pipe, 6 ... Overflow pipe, 7 ... Aeration apparatus, 8 ... Treatment water tank, 9 ... Treatment Water suction pipe,
10 cleaning nozzle, 11 outflow pipe, 12 cleaning pipe, 24
... Reaction tank, 31 ... Final sedimentation basin

Claims (4)

[Claims] 1. A solid-liquid separation apparatus for performing solid-liquid separation using a separation membrane immersed in a solid-liquid separation tank, wherein washing water is provided near the separation membrane in a direction substantially parallel to the surface of the separation membrane. A solid-liquid separation device provided with a washing nozzle that jets out. 2. A method for cleaning a solid-liquid separation device for performing solid-liquid separation by a separation membrane immersed in a solid-liquid separation tank, wherein the raw water in the solid-liquid separation tank is discharged to expose the separation membrane. Cleaning the solid-liquid separation apparatus by jetting washing water in a direction substantially parallel to the surface of the separation membrane from a washing nozzle provided in the vicinity of the separation membrane. 3. A method for cleaning a solid-liquid separation device, wherein solid-liquid separation is performed by a separation membrane immersed in a solid-liquid separation tank, wherein the separation membrane is immersed in raw water, Aeration cleaning by diffusing air from an aeration device installed in the apparatus, and after exposing raw water in the solid-liquid separation tank to expose the separation membrane, a separation nozzle is provided from a cleaning nozzle provided in the vicinity of the separation membrane. A method for cleaning a solid-liquid separation apparatus, wherein water spray cleaning by jetting cleaning water in a direction substantially parallel to a surface is selected according to the state of a separation membrane. 4. The method for cleaning a solid-liquid separation device according to claim 2, wherein the cleaning water is a part of treated water subjected to a solid-liquid separation process in the solid-liquid separation device.