JP2010131472A - Apparatus and method for concentrating backwash effluent in membrane filtration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for concentrating backwash effluent coming out of a filtration membrane, capable of adjusting the concentration of concentrated sludge to an intended level by mixing compressed dense solid matter of a pellet shape having high settleability contained in the backwash effluent of a membrane filtration device, with sucked and concentrated sludge. <P>SOLUTION: The apparatus for concentrating backwash effluent coming out of a filtration membrane includes: a membrane filtration device 11 having a casing for receiving raw water therein and a membrane filtration means for filtering raw water by a membrane; a backwash effluent tank 7; a sludge tank 1; a suction-type filtration/concentration means disposed in the sludge tank 1 for producing concentrated sludge by sucking and filtering the backwash effluent present in the sludge tank 1 while discharging filtered water to outside; a backwash-effluent return pipe 6 for returning the backwash effluent in the sludge tank 1 to the backwash effluent tank 7; a concentrated-sludge discharge pipe for discharging the sludge filtered/concentrated by the suction-type filtration/concentration means; and a concentrated sludge tank 15 connected downstream of the sludge tank 1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to an apparatus and a method for concentrating washing wastewater for membrane filtration, and more particularly, when concentrating washing wastewater for membrane filtration, a sedimentation property that is generated peculiar to membrane filtration together with solid matter attached to the membrane surface. The present invention relates to an apparatus and a method for concentrating washing wastewater for membrane filtration capable of concentrating highly compacted pellet-like solids.

Water purification plants, factories, and the like obtain tap water, pure water, and middle water through water treatment. For example, in a water purification plant, in general, chemicals are injected into raw water, and then coagulation sedimentation filtration using gravity sedimentation operation is performed. However, food poisoning due to contamination of bacteria such as Cryptosporidium in recent years As a result, more advanced water treatment is required. One of the methods is water purification by membrane. In this method, filtration is performed with a membrane having a fine pore size of about 0.1 μm or less, and this makes it possible to produce safe and stable tap water.

When water treatment is performed by membrane filtration, solid content gradually adheres to the membrane surface during the treatment step, and the membrane filtration capacity is lowered. Therefore, a regular cleaning operation is performed and removed. More specifically, solid water adhering to the membrane surface is removed by flowing the washing water in the direction opposite to the inflow direction of the raw water that is the subject of membrane filtration. being called.

The solid matter in the backwash wastewater generated by this washing is generally solidified through mechanical dehydration or sun drying after being concentrated by gravity settling, and is disposed of as industrial waste in the form of waste treatment or horticultural soil. The dehydrated liquid is used as raw water for tap water. In recent years, membrane filtration devices are often used in factories, department stores, buildings, etc. to make tap water and well water safer and more pure, or to reuse waste water as intermediate water. . Even in this case, periodic washing operations are performed to prevent a decrease in membrane filtration capacity, and concentration and dehydration operations are performed on the generated backwash waste water.

By the way, since the sludge discharged from the water purification process by coagulation sedimentation filtration contains 97 to 99% of water, it is concentrated in a gravity sedimentation tank and then mechanically dehydrated by pressurization or vacuum to 80% or less. The cake has a moisture content of, and the cake is disposed of as landfill.
However, the mechanical dehydration alone requires a large amount of energy for treatment, so the water load (moisture content) before mechanical dehydration is reduced in advance using the filtration and concentration devices described in Patent Document 1, Patent Document 2 and Patent Document 3. Saving labor.

In particular, in the sludge concentration described in Patent Document 1, a filter plate with a filter cloth pasted on both sides of an intermediate plate made of an absorbent material is placed in a sludge tank, and a filtrate discharging means is attached to this. Concentrate by filtration. This is called a siphon type filtration concentration apparatus.
The siphon type filtration concentrator has one or more filter plates in the sludge tank, one end of the filtrate discharge pipe is connected to this filter plate, and the other end is drawn out of the sludge tank. When sludge is filled inside, the sludge on the surface of the filter plate receives pressure due to the gravity of the sludge itself or the negative pressure (siphon force) acting on the filtrate discharge pipe, so that the sludge particles accumulate on the surface of the filter plate, Moisture enters the inside of the filter plate and is discharged out of the sludge tank through the filtrate discharge pipe. As a result, semi-solid concentrated sludge is formed on the filter cloth surface, but since unconcentrated sludge remains in the sludge tank, it is not possible to take out the concentrated sludge as it is. Is discharged to the outside of the sludge tank using a pump or the like, and then the concentrated sludge can be peeled off from the filter cloth surface by blowing pressurized air into the filter plate through a filtrate discharge pipe, for example. Since the peeled concentrated sludge falls to the bottom of the sludge tank, it is discharged outside the tank to obtain the concentrated sludge.

Therefore, the present inventor applied the siphon type filtration concentration device to the washing waste water of membrane filtration, not to the sludge discharged from the water purification process by the conventional coagulation sedimentation filtration, thereby membrane filtration. We considered that it would be possible to concentrate the washing wastewater, and tried the test as shown below.

For example, as shown in FIG. 8, the present apparatus discharges a sludge tank 1 having a short sludge chamber therein, a filter plate 2 suspended vertically in the sludge tank, and a filtrate filtered by the filter plate 2. Filtrate tube 3, filtrate valve 4 for discharging filtrate, drainage pump 5 for discharging unconcentrated wastewater in sludge tank 1 to the outside of the tank, drainage pipe for discharging unconcentrated wastewater in sludge tank 1 to the outside of the tank 6. Storage tank 7 for storing discharged unconcentrated waste water, discharge valve 8 for discharging concentrated sludge concentrated by the filter plate 2, vacuum pump 9 for forming siphon for discharging filtrate, siphon for discharging filtrate It is comprised by the vacuum valve 10 for forming. Here, the membrane filtration device 11 that discharges the washing wastewater is set in a vertical shape made of ceramic, is a dead-end system that feeds raw water from the membrane inner surface at the lower part of the membrane device, and filters the entire amount, and purifies water for a certain period of time. After filtration, membrane filtered water or purified water is supplied from the membrane permeation surface to peel off impurities and solids adhering to the membrane surface, and then sent to the storage tank 7 constituting the filtration concentration device as washing waste water. This washing wastewater is sent from the storage tank 7 to the sludge tank 1 by a pump or a dead weight drop using a height difference. The sludge tank 1 has a filter plate 2 in the tank, and a drain pipe 6 and a discharge valve 8 are connected to the lower part of the tank. The filter plate 2 is provided with a pipe through which the filtrate flows in the upper part of the combined filter cloth, and this pipe penetrates to the outside of the filter plate 2 at the upper part of the filter cloth. It is connected to the.

Next, an operation method using this apparatus will be described with reference to FIGS. 9, 10, 11, 12, and 13.

First, as shown in FIG. 9, the waste water discharged from the membrane filtration device 11 is temporarily stored in the storage tank 7 and then supplied to the sludge tank 1 with the filtrate valve 4, the discharge valve 8, and the vacuum valve 10 closed. Is done.

Next, as shown in FIG. 10, after the inside of the sludge tank 1 is filled with the washing waste water, the vacuum valve 10 is opened and the vacuum pump 9 is operated. Then, the inside of the filtrate tube 3 becomes a negative pressure, and the inside of the filter plate 2 connected to the filtrate tube 3 also becomes a negative pressure. Then, the backwash drainage on the surface of the filter plate 2 receives pressure, and the water of the backwash drainage enters the filter plate 2 through the filter cloth to become a filtrate, and the filtrate flows into the filtrate tube 3 and passes through the vacuum valve 10 to be vacuumed. It is discharged to the outside through the pump 9. Here, after the inside of the filtrate tube 3 is filled with the filtrate, the vacuum valve 10 is closed and the vacuum pump 9 is stopped, and when the filtrate valve 4 is opened after the inside of the filtrate tube 3 is filled with the filtrate, the filtrate is removed from the tube by siphon force. The water of the backwash drainage on the surface of the filter plate 2 begins to enter the inside of the filter plate 2 through the filter cloth, and the solid content of the backwash wastewater begins to aggregate on the surface of the filter plate 2 to become concentrated sludge. If the operation is continued, the amount of washing wastewater in the sludge tank 1 is reduced, so that the washing wastewater is supplied from the storage tank 7 so that the filter plate 2 is not exposed above the liquid level.

When the operation is continued for a certain time, the concentrated sludge aggregated on the surface of the filter plate 2 is formed in a plate shape. This time varies depending on the quality of the raw water before membrane filtration, the ability of the membrane to be treated, and the aging of the membrane. After the plate-shaped concentrated sludge is formed on the surface of the filter plate 2, as shown in FIG. 11, the unconcentrated washing wastewater in the sludge tank 1 is sent to the storage tank 7 by the drainage pump 5 and the drainage pipe 6. It discharges from the tank 1 and makes the sludge tank 1 empty.

Next, as shown in FIG. 12, after the filtrate valve 4 is closed, compressed air is supplied into the filtrate pipe 3, and the concentrated sludge formed on the surface of the filter plate 2 is peeled off to lower the sludge tank 1. Let fall.

Next, as shown in FIG. 13, the above-described peeled sludge accumulated in the lower part of the sludge tank 1 is discharged out of the tank through the discharge valve 8 as concentrated sludge.
By the above operation, it is possible to concentrate the backwash waste water from membrane filtration.

As described above, the present inventor conducted an experiment using a siphon filtration concentrator for the backwash waste water after membrane filtration using a ceramic membrane, and confirmed that concentration was possible. In addition to the sludge solid matter adhering to the membrane surface, the backwash wastewater contains a large amount of solid matter peculiar to membrane filtration. Has been found to be difficult to concentrate with a siphon filtration concentrator.

More specifically, the solid matter peculiar to membrane filtration is mainly a compacted pellet-like solid matter produced by pumping the treatment liquid to be filtered through the filtration membrane. Although the shape depends on the through-hole of the membrane, it is usually cylindrical with a diameter of about 1 mm and a length of about 3 to 10 mm. Since this pellet-like solid is highly settled, backwash wastewater is contained in the sludge tank. When supplied, unlike the sludge solid matter adhering to the membrane surface, it is deposited on the bottom of the sludge tank without being suction filtered toward the filter plate 2.

In this case, the pellet-like solid precipitated on the bottom of the sludge tank is separated from the concentrated sludge that has been suction filtered through the filter plate 2, and is discharged to the outside by opening the discharge valve 8, for example. If it peels off from the filter plate 2 and is discharged to the outside, and separately performs post-processing such as transport processing and dehydration processing, the efficiency of such post-processing is reduced.

More specifically, the sludge concentrated in the sludge tank is discharged to the outside, transported and dehydrated, and finally formed into a solidified cake that can be disposed of, depending on the concentration of the concentrated sludge. Necessary conveyance form or dewatering form is affected. That is, if a solid pellet with a high concentration is transported alone and dehydrated, a special pump such as a mono pump is required instead of a general centrifugal pump, and the diameter of the transport pipe needs to be increased. When general mechanical dehydration such as a filter press is performed, effective dehydration becomes difficult. Furthermore, due to these circumstances, maintainability, reliability, or space in post-processing is impaired, and as a whole, it is difficult to perform efficient post-processing.

On the other hand, the amount of compacted pellet-like solids varies depending on the quality of raw water, the type and amount of chemicals added to the raw water, or the season. For this reason, even if the post-treatment is performed in a state where the pellet-like solids precipitated at the bottom of the sludge tank are mixed with the suction-concentrated sludge, the suction-concentrated sludge, and the supernatant, depending on the amount of the fluctuating pellet-like solids. By adjusting the mixing ratio of unconcentrated backwash wastewater that is a liquid, it is desirable that post-treatment is possible as a concentrated sludge having a desired concentrated concentration that contributes to the efficiency of the post-treatment.
Japanese Patent Publication No. 60-59002 Shoko 62-49087 Shoko 62-49088

Therefore, in view of the above technical problems, the object of the present invention is to obtain a new concentrated sludge by mixing the compacted pelletized solid material with high sedimentation contained in the backwash waste water of the membrane filtration apparatus with the suction concentrated sludge. In order to concentrate the backwash waste water of the filtration membrane, which can be adjusted to a desired concentration concentration, so that a series of processing such as transport processing and dehydration processing that are post-processing can be efficiently carried out. It is to provide an apparatus and method.

In order to achieve the above object, an apparatus for concentrating the backwash waste water of the filtration membrane according to the present invention is:
An apparatus for concentrating backwash wastewater from a filtration membrane,
A membrane filtration device having a casing for receiving raw water therein, and a membrane filtration means provided in the casing for membrane filtration of the raw water;
A backwash drainage tank connected to the casing for storing backwash drainage by membrane filtration;
A sludge tank connected to the downstream side of the backwash drainage tank for receiving backwash drainage stored in the backwash drainage tank;
A suction-type filtration concentration means provided in the sludge tank, wherein the backwash waste water in the sludge tank is suction filtered to generate concentrated sludge in the sludge tank, while discharging filtered water to the outside. Suction filtration and concentration means;
A backwash drainage return pipe for connecting the backwash drainage tank and the bottom of the sludge tank and returning the backwash drainage in the sludge tank to the backwash drainage tank;
In the apparatus having a concentrated sludge discharge pipe connected to the bottom of the sludge tank and for discharging the sludge filtered and concentrated by the suction filtration and concentration means,
Further, the concentrated sludge discharge pipe having a concentrated sludge tank connected to the downstream side of the sludge tank, and connecting the sludge tank and the concentrated sludge tank, discharges unconcentrated backwash wastewater or concentrated sludge. It is set as the structure by which the discharge valve for adjusting quantity is provided.

The present invention attaches to the membrane by filtering the raw water as a problem unique to membrane filtration in which filtration is performed in a form that allows passage of countless small-diameter through holes provided in the membrane by pumping the treatment liquid to be filtered. When backwashing solids to be backwashed, the backwash water contains pellets solids consolidated under a predetermined filtration pressure in addition to solids adhering to the membrane surface. It is different from the solids of the material and has already been concentrated, but on the other hand, paying attention to the high sedimentation property, including such pelleted solids, it is intended to concentrate the sludge treatment of backwash water .

According to the apparatus for concentrating the backwash drainage of the filtration membrane having the above-described configuration, the suction membrane is concentrated in the sludge tank that receives the backwash drainage from the backwash water tank in which the backwash water is stored. Concentrated sludge is generated in the sludge tank by suction filtration of the washing waste water, while filtered water can be discharged to the outside. On the other hand, during this time, the pellet-like solid matter is not sucked by the suction-type filtration concentration means, but settles to the bottom of the sludge tank, and the backwash wastewater in the sludge tank accumulates at the bottom of the sludge tank with time. It is separated into a pellet-like solid and a supernatant. This compacted pellet-like solid is discharged to the outside through the concentrated sludge discharge pipe together with unconcentrated backwash wastewater, transferred to the concentrated sludge tank connected downstream of the sludge tank, and then remains in the sludge tank. Return the unconcentrated backwash wastewater to the backwash drainage tank through the backwash drainage return pipe, peel the concentrated sludge in the emptied sludge tank, and store it at the bottom of the sludge tank. Separately, it is transferred to a concentrated sludge tank, where it is mixed with compacted pellet-like solids and unconcentrated backwash waste water to form new concentrated sludge.

At this time, by adjusting the opening time of the discharge valve, it is possible to adjust the discharge amount of the unconcentrated backwash wastewater that is transferred to the concentrated sludge tank together with the compacted pellet-like solids. The concentrated concentration of the concentrated sludge mixed in the concentrated sludge tank, the compacted pellet-like solids, and the unconcentrated backwash wastewater can be set to a desired concentration outside the tank.

In this way, by adjusting the new concentrated sludge generated in the concentrated sludge tank to a desired concentrated concentration, a series of treatments such as conveying and dewatering the concentrated sludge when post-treating such concentrated sludge. Can be performed efficiently.
In particular, even if the amount of compacted pellet-like solids varies depending on the quality of raw water, the type and amount of chemicals added in the season and water purification process, it is concentrated by adjusting the opening time of the discharge valve. It is possible to finely adjust the discharge amount of unconcentrated backwash wastewater transferred to the sludge tank. In this case, it is necessary to discharge the compacted pellet-like solid that settles at the bottom of the sludge tank to the outside. Assuming that the opening time of the discharge valve is secured over the required time, if there is a large amount of compacted pellet-like solids, it is not concentrated by adjusting the opening time of the discharge valve accordingly. If the discharge amount of backwash wastewater is increased, and if the amount of compacted solid pellets is small, adjust the opening time of the discharge valve accordingly to reduce the discharge amount of unconcentrated backwash wastewater. By reducing It is possible to adjust the concentration of the concentrated sludge produced in the concentrated sludge tank.

Further, the backwash drainage return pipe may be provided to branch from the concentrated sludge discharge pipe upstream of the discharge valve, and the backwash drainage return pipe may be provided with a branch valve.

In order to achieve the above object, the method for concentrating the backwash waste water of the filtration membrane according to the present invention is:
A method for concentrating backwash wastewater from a filtration membrane,
Supplying backwash wastewater from the filtration membrane into the sludge tank;
A step of producing concentrated sludge in the sludge tank by suction-filtering backwash wastewater in the sludge tank;
Discharging the compacted pellet-shaped solids contained in the backwash drainage from the bottom of the sludge tank to the outside of the sludge tank;
The discharging step includes a step of adjusting the amount of unconcentrated backwash wastewater discharged out of the sludge tank together with the compacted pellet-like solid,
Furthermore, discharging the unconcentrated backwash wastewater remaining in the sludge tank to the outside of the sludge tank,
The concentrated sludge that has been filtered off by suction is discharged outside the sludge tank and mixed with the compacted pellet-like solid matter and the unconcentrated backwash wastewater whose amount of drainage is adjusted outside the sludge tank. Producing a new concentrated sludge having
It has the composition of having.

According to the method for concentrating the backwash wastewater of the filtration membrane having the above configuration, when the backwash wastewater supplied into the sludge tank is concentrated, the compacted pellet-like solid matter accumulated at the bottom of the sludge tank and By discharging the unconcentrated backwash wastewater to the outside of the sludge tank, and then mixing the concentrated sludge filtered by suction with the compacted pellet solid and the unconcentrated backwash wastewater outside the sludge tank, It is possible to produce new concentrated sludge. At that time, by adjusting the amount of unconcentrated backwash wastewater discharged to the outside of the sludge tank together with the compacted pellet-like solids, the concentrated pelletized solids with a high concentration concentration, the concentrated sludge by suction filtration with a low concentration concentration It is possible to adjust the concentration concentration of new concentrated sludge consisting of unconcentrated backwash wastewater amount to the desired concentration, thereby making it possible to carry out new post treatment of concentrated sludge, such as transport processing, dewatering processing, etc. It is possible to efficiently perform a series of processes.

Further, the predetermined concentrated sludge concentration is 4.0% or more, and it is preferable to further include a step of conveying new concentrated sludge by a centrifugal pump, performing a filter press-type dehydration treatment, and solidifying.

According to the apparatus for concentrating the backwash waste water of the filtration membrane according to the present invention, the compacted pellet-like solid matter accumulated at the bottom of the sludge tank, the concentrated sludge suction-filtered in the sludge tank, and the sludge tank By mixing unconcentrated backwash waste water in a concentrated sludge tank, it is possible to obtain a new concentrated sludge.
At this time, by adjusting the opening time of the discharge valve, it is possible to adjust the discharge amount of the unconcentrated backwash wastewater that is transferred to the concentrated sludge tank together with the compacted pellet-like solids. The concentrated concentration of the concentrated sludge mixed in the concentrated sludge tank, the compacted pellet-like solids, and the unconcentrated backwash wastewater can be set to a desired concentration outside the tank.
In this way, by adjusting the new concentrated sludge generated in the concentrated sludge tank to the desired concentrated concentration, a series of treatments such as conveying and dewatering the concentrated sludge can be efficiently performed when post-treating the concentrated sludge. Can be performed.

Embodiments of the present invention will be described below in detail with reference to the drawings. In the following embodiments, the membrane filtration device is a dead-end type filtration membrane device using a ceramic membrane, while the filtration membrane device is a conventionally known siphon-type filtration concentration device as a backwash drainage filtration concentration device. Adopted.

FIG. 1 is a basic configuration diagram of a filtration and concentration apparatus according to an embodiment of the present invention. The filtration concentration apparatus of the present invention comprises a filtrate pipe 3 for discharging a filtrate filtered by a filter plate 2 suspended vertically in a sludge tank 1 having a short sludge chamber therein, and a filtrate valve 4 for discharging the filtrate. , A drainage pump 5 for discharging unconcentrated wastewater in the sludge tank 1 to the outside of the tank, a drain pipe 6 for discharging unconcentrated wastewater in the sludge tank 1 to the outside of the tank, and storage for storing the discharged unconcentrated wastewater It comprises a tank 7, a discharge valve 8 for discharging concentrated sludge concentrated by the filter plate 2, a vacuum pump 9 and a vacuum valve 10 for forming a siphon for discharging the filtrate. Although the number of the filter plates 2 is one in FIG. 1, the case where a plurality of the filter plates are included is generally used. The filter plate 2 is provided with a pipe through which the filtrate flows in the upper part of the combined filter cloth, and this pipe penetrates to the outside of the filter plate 2 at the upper part of the filter cloth. It is connected to the.

Moreover, the membrane filtration apparatus 11 is a dead end system in which a cylindrical cylindrical membrane made of ceramic is set vertically, feeds raw water from the membrane inner surface at the bottom of the membrane apparatus, and filters the entire amount. Membrane filtered water is supplied from the membrane permeation surface to peel off impurities and solids adhering to the membrane surface, and then sent to the storage tank 7 constituting the filtration concentration device as washing waste water. This washing waste water is sent from the storage tank 7 to the sludge tank 1.

Here, the backwash waste water (filtered waste water) after membrane filtration contains a large amount of solid matter peculiar to membrane filtration, apart from sludge solid matter adhering to the membrane surface. The solid matter is a compacted pellet-like solid matter 17, and the size and shape depend on the filtration pressure or the like, but is usually a cylindrical shape having a diameter of about 1 mm and a length of about 3 to 10 mm. Unlike the sludge-like solid content adhering to the membrane surface when the backwash wastewater is supplied into the sludge tank 1, the material 17 is not suction filtered toward the filter plate 2 when the backwash wastewater is supplied into the sludge tank 1. It settles at the bottom of sludge tank 1.
In the case of the dead end method, tube bundles each provided with infinite number of micron-diameter through-holes (not shown) on the side surface are accommodated in a casing (not shown) in a vertical state and should be filtered from one end of the tube bundle. As the stock solution flows through the pipe toward the other end, which is the closed end, the stock solution passes through innumerable through-holes, and is filtered and guided to the outside of the tube bundle in the casing and from the discharge port provided in the casing. The filtrate is allowed to flow out. At this time, by pressing the stock solution toward the other end which is a closed end in each tube, a compacted pellet is formed in the vicinity of the other end. Therefore, the diameter and number of the compacted pellets formed correspond to the inner diameter of the tube and the number of tube bundles. When removing the compacted pellets formed in this way by backwashing water, each pipe is made to flow in a direction opposite to the case of filtration from the outlet provided in the casing toward each tube bundle. Then, the compacted pellets are washed away in the vicinity of the other end by the washing water that has passed through the infinite number of through holes and led into the pipe, and flows out together with the washing water from the pipe toward one end that is an open end.
On the other hand, in the case of the cross flow method, unlike the case of the dead end method, each of the tube bundles has a form that vertically penetrates the casing, and does not have the other end that is a closed end in the casing. As the stock solution to be filtered flows from inside the pipe, the stock solution passes through innumerable through-holes and is thereby filtered, led to the outside of the tube bundle in the casing, and the filtrate flows out from the outlet provided in the casing. The stock solution that does not pass through the through-hole flows through the pipe as it is and is discharged to the outside of the casing. At this time, unlike the case of the dead end method, a compact pellet is not formed in the vicinity of the other end, which is a closed end, but adhesion of organic matter or viscous material on the inner wall portion of the tube immediately before passing through innumerable through holes. A similar compacted pellet is formed due to. When the compacted pellets formed in this way are removed by backwashing water, as in the case of the dead end method, the washing water is supplied to each tube bundle from the outlet provided in the casing in the opposite direction to the filtration. By flowing toward each other, the compacted pellets attached to the inner wall of the pipe are washed away by the washing water guided through the infinite number of through holes in each pipe, and one end which is an open end from the inside of the pipe together with the washing water. Spill out towards. Alternatively, the compacted pellets may be removed by flowing washing water in the opposite direction to the stock solution in each tube.

The drain pipe 6 is attached to a pipe before the discharge valve 8, and a branch valve 14 is provided there, so that the unconcentrated washing waste water can be sent to an arbitrary system by switching to the discharge valve 8. Yes. On the downstream side of the discharge valve 8, a concentrated sludge tank 15 is provided on the surface of the filtration plate 2 that has fallen into the sludge tank 1 or the pelletized solid matter having high sedimentation that has settled in the sludge tank 1. The formed and concentrated sludge can be sent to the concentrated sludge tank 15 for storage. The capacity of the concentrated sludge tank 15 is appropriately selected according to the amount of compacted solid pellets generated, the amount of sludge formed and concentrated on the surface of the filter plate 2, or the amount of unconcentrated backwash wastewater. do it. As a modification, the drain pipe 6 may be directly connected to the bottom of the sludge tank 1.

Here, the operation method of this embodiment using this apparatus will be described with reference to FIGS. 2, 3, 4, 5, 6, and 7.

First, as shown in FIG. 2, the drainage discharged from the membrane filtration device 11 is temporarily stored in the storage tank 7 and then supplied to the sludge tank 1 with the filtrate valve 4 and the vacuum valve 10 closed.
Next, as shown in FIG. 3, after the inside of the sludge tank 1 is filled with the washing waste water, the vacuum valve 10 is opened and the vacuum pump 9 is operated to set the inside of the filter cloth to a negative pressure, and the washing waste water is filtered through the filter plate 2 and filtrated. Into the filtrate tube 3, the filtrate tube 3 is filled with the filtrate, the vacuum valve 10 is closed, the filtrate valve 4 is opened, and the filtrate is discharged out of the tube by siphon force. If the operation is continued, the amount of washing wastewater in the sludge tank 1 is reduced, so that the washing wastewater is supplied from the storage tank 7 so that the filter plate 2 is not exposed from the liquid surface.

Next, as shown in FIG. 4, after continuing the state of FIG. 3 for a certain period of time, the discharge valve 8 is opened, and the settled compacted and highly compacted pelletized solid in the sludge tank 1 is not yet removed. It is sent to the concentrated sludge tank 15 together with the concentrated backwash waste water. As a result, unconcentrated washing wastewater remains in the sludge tank 1. Here, by arbitrarily setting the opening time of the discharge valve 8, the amount of unconcentrated backwash wastewater sent to the concentrated sludge tank 15 changes, and the concentration of the concentrated sludge changes. That is, it is possible to adjust the concentrated sludge concentration by adjusting the opening time of the discharge valve 8.
The adjustment method of the opening time of the discharge valve 8 can be performed as follows, for example. The discharge valve 8 is, for example, a motor-driven valve, and the opening and closing of the valve is controlled by driving the motor. By controlling the driving of the motor, the discharge valve 8 is controlled by the following sensor signal. Adjust the opening time. More specifically, a liquid level detector (not shown) that detects the level of unconcentrated backwash wastewater in the sludge tank 1 and a solid content that detects the level of concentrated sludge accumulated in the bottom of the sludge tank 1. When a non-concentrated backwash wastewater and concentrated sludge are discharged through the discharge valve 8 with a detector (not shown), the level of the unconcentrated backwash wastewater by the liquid level detector is concentrated by the solid content detector. By driving the motor and keeping the discharge valve 8 open until it falls below the sludge level, the discharge amount of unconcentrated backwash wastewater transferred to the concentrated sludge tank 15 together with the compacted pellet solids is reduced. It is possible to adjust the concentration sludge mixed in the concentrated sludge tank 15 outside the sludge tank 1, the compacted pellet-like solids, and the concentrated sludge generated by the unconcentrated backwash waste water. To make the concentration concentration the desired concentration It is a function. Note that the solid content detector may be one that detects density difference, conductivity difference, or ultrasonic waves, for example.

Next, as shown in FIG. 5, the branch valve 14 is opened, and the unconcentrated washing wastewater remaining in the sludge tank 1 is sent to the storage tank 7 using the drain pump 5 and the drain pipe 6.

Next, as shown in FIG. 6, after the filtrate valve 4 is closed, compressed air is supplied into the filtrate pipe 3, and the concentrated sludge formed on the surface of the filter plate 2 is peeled off to the lower part of the sludge tank 1. Drop it.

Next, as shown in FIG. 7, the branch valve 14 is closed, the discharge valve 8 is opened, and the concentrated sludge formed on the surface of the filter plate 2 dropped into the sludge tank 1 is sent to the concentrated sludge tank 15. As a result, the suction-concentrated sludge is mixed in the concentrated sludge tank 15 with the compacted pellet-like solids and the unconcentrated backwash wastewater that have already been sent into the concentrated sludge tank 15 to generate new concentrated sludge. Is done.
Next, the new concentrated sludge is transported to a mechanical dehydration apparatus such as a filter press type as post-treatment, where dehydration is performed, and finally a solidified cake that can be disposed of is generated.

Here, in an experiment by the inventors, when concentration was performed using a siphon type filtration concentrator for washing waste water of a filter using a membrane made of ceramic, a dead end type membrane filter using a ceramic membrane was used. The SS concentration of the washing wastewater is approximately 0.3%, and the compacted pellet-like solid 17 contained therein is formed in a cylindrical shape having a diameter of about 1 mm and a length of about 3 to 10 mm. Was not contained in the concentrated sludge formed on the filter plate 2 but precipitated in the lower part of the sludge tank. At this time, the SS concentration of the concentrated sludge adhering to the filter plate 2 of the siphon type filter concentration apparatus was about 6.1%.

According to the above operation method, it was confirmed that when such concentrated sludge was mixed with the washing waste water containing the compacted pellet-like solid matter 17, it became a concentrated sludge having an SS concentration of 4.0% or more. When the concentrated sludge extracted here is subjected to mechanical dehydration such as filter press later, it is known that mechanical dewatering can be effectively performed if the SS concentration of the concentrated sludge is 4.0% or more, and the SS concentration is 4.0%. If it is about the extent, it can be conveyed by a centrifugal pump, and there is an advantage that it is not necessary to use an expensive device such as a snake pump.

According to the apparatus for concentrating the backwash waste water of the filtration membrane having the above configuration, the suction filtration and concentration means in the sludge tank 1 receiving the backwash waste water from the storage tank 7 in which the back wash water is stored. By suction filtration of the backwash waste water, concentrated sludge is generated in the sludge tank 1, while filtered water can be discharged to the outside. On the other hand, during this time, the pellet-like solid matter is not sucked by the suction-type filtration and concentration means, but settles on the bottom of the sludge tank 1, and as time passes, the backwash wastewater in the sludge tank 1 becomes the bottom of the sludge tank 1. Are separated into a compacted pellet-like solid collected in the supernatant and a supernatant. This compacted pellet-like solid matter is discharged to the outside through the concentrated sludge discharge pipe together with the unconcentrated backwash waste water, transferred to the concentrated sludge tank 15 connected to the downstream side of the sludge tank 1, and then the sludge tank 1 Unconcentrated backwash wastewater remaining inside is returned to the storage tank 7 through the drain pipe 6, the concentrated sludge is peeled off in the emptied sludge tank 1, and stored at the bottom of the sludge tank 1, and is compacted pelletized solid Separately from the product, it is transferred to a concentrated sludge tank 15, where it is mixed with a compacted pellet-like solid and unconcentrated backwash wastewater to obtain a new concentrated sludge.

At this time, by adjusting the opening time of the discharge valve 8, it is possible to adjust the discharge amount of the unconcentrated backwash wastewater transferred to the concentrated sludge tank 15 together with the compacted pellet-like solid, The concentration concentration of the concentrated sludge mixed in the concentrated sludge tank 15, the compacted pellet solids, and the concentrated sludge generated by the unconcentrated backwash waste water outside the sludge tank 1 is set to a desired concentration. Is possible.

In this way, by adjusting the new concentrated sludge generated in the concentrated sludge tank 15 to a desired concentrated concentration, when post-treating such concentrated sludge, a series of operations such as conveying the concentrated sludge and dehydrating treatment are performed. Processing can be performed efficiently.
In particular, by adjusting the opening time of the discharge valve 8 even if the amount of compacted pellet-like solids varies depending on the quality of raw water, the type of chemicals added in the season and the water purification process, the amount, It is possible to finely adjust the discharge amount of unconcentrated backwash wastewater transferred to the concentrated sludge tank 15, and in this case, the compacted pellet-like solid that settles at the bottom of the sludge tank 1 is discharged to the outside. Assuming that the opening time of the discharge valve 8 is ensured over the time required to do so, if the amount of compacted pellet solids generated is large, the opening time of the discharge valve 8 is adjusted to be longer accordingly. Therefore, if the discharge amount of unconcentrated backwash wastewater is increased while the generation amount of compacted pellet-like solids is small, the opening time of the discharge valve 8 is adjusted to be shorter accordingly, Reduces wastewater discharge The Rukoto, it is possible to adjust the concentration of the concentrated sludge that is generated in the concentrated sludge tank 15.

Although the embodiments of the present invention have been described in detail above, various modifications or variations can be made by those skilled in the art without departing from the scope of the present invention. For example, in the present embodiment, a membrane filtration device premised on a dead-end type ceramic membrane has been described as an example. However, a highly settled compacted pellet-like solid generated in a membrane filtration device is Such compacted pellet-like solids may occur in cross-flow ceramic membrane filtration devices or membrane filtration devices using organic membranes. In this case, the present invention is effectively applied. Further, in the present embodiment, the siphon type filtration and concentration device has been described as an example of the suction type filtration and concentration device. However, the present invention is not limited thereto, and the present invention is applicable to any type that sucks and filters sludge in a sludge tank. Is effectively applied.

It is the schematic which shows embodiment of the filtration concentration apparatus which concentrates the washing | cleaning waste_water | drain of a membrane filtration apparatus based on this invention. It is an operation | movement figure which concentrates washing | cleaning waste water using the filtration concentration apparatus of FIG. It is an operation | movement figure which concentrates washing | cleaning waste water using the filtration concentration apparatus of FIG. It is an operation | movement figure which concentrates washing | cleaning waste water using the filtration concentration apparatus of FIG. It is an operation | movement figure which concentrates washing | cleaning waste water using the filtration concentration apparatus of FIG. It is an operation | movement figure which concentrates washing | cleaning waste water using the filtration concentration apparatus of FIG. It is an operation | movement figure which concentrates washing | cleaning waste water using the filtration concentration apparatus of FIG. It is the schematic which shows the conventional embodiment of the filtration concentration apparatus which concentrates the washing | cleaning waste_water | drain of a membrane filtration apparatus. It is a conventional operation | movement figure which concentrates washing | cleaning waste water using the filtration concentration apparatus of FIG. It is a conventional operation | movement figure which concentrates washing | cleaning waste water using the filtration concentration apparatus of FIG. It is a conventional operation | movement figure which concentrates washing | cleaning waste water using the filtration concentration apparatus of FIG. It is a conventional operation | movement figure which concentrates washing | cleaning waste water using the filtration concentration apparatus of FIG. It is a conventional operation | movement figure which concentrates washing | cleaning waste water using the filtration concentration apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sludge tank 2 Filter plate 3 Filtrate pipe 4 Filtrate valve 5 Drain pump 6 Drain pipe 7 Reservoir 8 Discharge valve 9 Vacuum pump 10 Vacuum valve 11 Membrane filtration device 13 Drain valve 14 Branch valve 15 Concentrated sludge tank 16 Concentrated sludge 17 Consolidation Solid matter

Claims (4)

An apparatus for concentrating backwash wastewater from a filtration membrane,
A membrane filtration device having a casing for receiving raw water therein, and a membrane filtration means provided in the casing for membrane filtration of the raw water;
Backwash drainage tank connected to the casing for storing backwash drainage by membrane filtration;
A sludge tank connected to the downstream side of the backwash drainage tank for receiving backwash drainage stored in the backwash drainage tank;
A suction-type filtration concentration means provided in the sludge tank, wherein the backwash waste water in the sludge tank is suction filtered to generate concentrated sludge in the sludge tank, while discharging filtered water to the outside. Suction filtration and concentration means;
A backwash drainage return pipe for connecting the backwash drainage tank and the bottom of the sludge tank, and returning the backwash drainage in the sludge tank to the backwash drainage tank;
In the apparatus having a concentrated sludge discharge pipe connected to the bottom of the sludge tank and for discharging the sludge filtered and concentrated by the suction filtration and concentration means,
Further, the concentrated sludge discharge pipe having a concentrated sludge tank connected to the downstream side of the sludge tank, and connecting the sludge tank and the concentrated sludge tank, discharges unconcentrated backwash wastewater or concentrated sludge. A discharge valve for adjusting the amount is provided,
A device characterized by that.   The apparatus according to claim 1, wherein the backwash drainage return pipe is provided to branch from the concentrated sludge discharge pipe upstream of the discharge valve, and the backwash drainage return pipe is provided with a branch valve. . A method for concentrating backwash wastewater from a filtration membrane,
Supplying backwash wastewater from the filtration membrane into the sludge tank;
A step of producing concentrated sludge in the sludge tank by suction-filtering backwash wastewater in the sludge tank;
Discharging the compacted pellet-shaped solids contained in the backwash drainage from the bottom of the sludge tank to the outside of the sludge tank;
The discharging step includes a step of adjusting the amount of unconcentrated backwash wastewater discharged out of the sludge tank together with the compacted pellet-like solid,
Furthermore, discharging the unconcentrated backwash wastewater remaining in the sludge tank to the outside of the sludge tank,
The concentrated sludge that has been filtered off by suction is discharged outside the sludge tank and mixed with the compacted pellet-like solid matter and the unconcentrated backwash wastewater whose amount of drainage is adjusted outside the sludge tank. Producing a new concentrated sludge having
A method characterized by comprising.     4. The method according to claim 3, further comprising a step of conveying the new concentrated sludge by a centrifugal pump, performing a filter press-type dewatering treatment, and solidifying the predetermined concentrated sludge concentration of 4.0% or more.

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