JP2668010B2 - Sludge filtration and concentration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for filtering and condensing sludge generated in water treatment, industrial water treatment, sewage treatment, human waste treatment, industrial waste water treatment, etc. The present invention relates to a sludge filtration / concentration apparatus used as a pretreatment for dehydration using a bed, a pressure dehydrator, a centrifugal dehydrator, a freeze-thaw machine, or the like.

[Prior art]

Conventionally, when dewatering sludge generated in water treatment, industrial water treatment, sewage treatment, human waste treatment, industrial wastewater treatment, etc., an inorganic coagulant such as iron salt, lime, or a polymer coagulant is added to the sludge. And a dewatering aid such as an underwater granulation dehydrator, a vacuum filter, a pressure filter, a centrifugal dehydrator, and a belt press dehydrator. In recent years, in particular in the fields of water treatment, industrial water treatment, and the like, the number of cases of dehydration using a sun-dry bed or a pressure dehydrator without chemical injection has been increasing. When performing such a dehydration treatment, the concentration of sludge when supplying to a solar drying bed or a pressure dehydrator is very important. The efficiency drops significantly. Conventionally, the sedimentation method (sedimentation method) such as thickener has been used for pre-concentration of sludge. However, recently, the ratio of components that are difficult to concentrate, such as organic substances and aluminum hydroxide, has increased in the sludge. Have not been able to be concentrated.

For this reason, conventionally, a filtration and concentration device as shown in FIG. 5 has been used. That is, a sludge thickening part 3 and a liquid collecting part 4 for collecting a filtrate on the sludge thickening part 3 are formed in the closed tank 1 by a horizontal partition plate 2, and the sludge thickening part 3 is provided with a sludge inlet pipe provided with a sludge inlet valve 5. A filtrate outlet pipe 8 having a filtrate valve 7 and an air vent pipe 10 having an air vent valve 9 are connected to the liquid collecting part 4. Further, in the sludge concentrating unit 3, a tubular filter element (hereinafter simply referred to as an element) 11 having a filter cloth wrapped around the outer periphery of the support and having one end opened and the other end closed is provided. Is fixed to the partition plate 2, and the filtrate permeated into the element 11 flows into the liquid collecting section 4 via its open end. A concentrated sludge discharge portion 12 is formed in a lower part in the closed tank 1, and a concentrated sludge discharge pipe 14 provided with a concentrated sludge discharge valve 13 is continuously provided.

[0006] In such a filtration and concentration apparatus, as shown in FIG. 6, the sludge inflow pipe 6 is connected to the discharge side of a sludge pump 16 whose suction side is connected to the raw sludge storage tank 15, and is stored in the raw sludge storage tank 15. The raw sludge is fed to the sludge inflow pipe 6 by the sludge pump 16.
Is supplied to the sludge concentrating section 3 in the closed tank 1 through the sludge pump 16. The raw sludge is injected by the sludge pump 16 or the pressure in the liquid collecting section 4 is reduced, so that the differential pressure generated inside and outside the element 11 causes While the sludge adheres to the outside and is concentrated, the filtrate permeates into the inside of the element 11, is collected in the liquid collecting section 4, and flows out from the filtrate outflow pipe 8. When the sludge is attached to the outside of the element 11 and concentrated to a predetermined concentration by such an operation, the supply of the raw sludge is stopped, the return valve 17 is opened, and the unconcentrated sludge in the sludge concentration section 3 is returned from the return pipe 18. To the raw sludge storage tank 15, and then a return valve 17
Is closed, and the inside of the sludge thickening section 3 is opened to the atmosphere, and then the pressurized air or the like is blown into the element 11 to peel off the thickened sludge adhering to the outside.
And the concentrated sludge discharge valve 13 is opened to be discharged from the concentrated sludge discharge pipe 14. After the separation and discharge steps of the concentrated sludge, the concentrated sludge discharge valve 13 is closed, the opening of the sludge concentration section 3 to the atmosphere is shut off, and the sludge in the raw sludge storage tank 15 is again removed by the sludge pump 16. , And then filtration and concentration are performed as described above.

[0005]

The conventional apparatus having such a sludge filling step, filtration and concentration step, unconcentrated sludge discharge step, concentrated sludge stripping and discharge step as one cycle has many problems as follows. Had. The return of the non-concentrated sludge from the closed tank 1 to the raw sludge storage tank 15 in the non-concentrated sludge discharge step is preferably performed by a natural flow method in order to reduce the power cost and the like.
The high water level (HWL) of No. 5 needs to be lower than that of the closed tank 1, and the raw sludge storage tank 15 must be buried or the closed tank 1 must be elevated on level ground, which increases construction costs. When the unconcentrated sludge is returned to the raw sludge storage tank 15, the capacity of the raw sludge storage tank 15 must be large enough to allow for the maximum amount of returned sludge, and becomes very large. The amount of unconcentrated sludge in the closed tank 1 at the end of the filtration / concentration step is a very large amount of about 60 to 80% excluding the liquid collecting section 4 in the closed tank 1 and the filtrate section in the element 11. Is. Therefore, the time required for the unconcentrated sludge discharge step and the sludge filling step before the next filtration and concentration step, that is, so-called miscellaneous time, increases, and the time required for one cycle also increases. Further, the operation of the sludge pump 16 in the sludge filling step increases the power cost. By the unconcentrated sludge discharging step, the element 11 in the closed tank 1 comes into contact with air. Further, if the concentrated sludge is peeled off by air blow or the like, not only the peeling cannot be carried out uniformly, but also the filtrate or the like remaining or adhering to the inside of the element 11 is in an oxidized state. Therefore, in the raw sludge storage tank 15, or in a concentration operation or the like performed before that,
Iron, manganese, etc., which have been ionized in the reduced state, are oxidized and adhere to the element 11, which lowers the air permeability and the filtration rate, resulting in a significantly shortened life. The present invention solves such a conventional problem and concentrates a sludge enrichment unit in a filtration concentrator while being filled with sludge without performing a conventional sludge filling process and an unconcentrated sludge discharging process. An object of the present invention is to provide a sludge filtration / concentration device capable of removing and discharging sludge, reducing rough time, running cost, simplifying equipment, and preventing element clogging.

[0006]

According to the present invention, a sludge thickening section 3 and a liquid collecting section 4 are formed in a closed tank 1 by a partition plate 2, and one end is opened in the sludge thickening section 3 and the other end is opened. A plurality of tubular filter elements 11 having closed are suspended from the partition plate 2,
The open end communicates with the liquid collecting part 4, a filtrate outlet pipe 8 having a filtrate valve 7 is provided in the liquid collecting part 4, and a sludge inflow valve 5 is provided in the sludge concentrating part 3 of the closed tank 1. In an apparatus for supplying sludge from a sludge inflow pipe 6 and allowing the filtrate permeated into the tubular filter element 11 to flow out of the tank via a liquid collecting section 4 to perform filtration and concentration of the sludge, the sludge concentration section 3 An air bleeding pipe 20 communicating with the upper part, and an air bleeding valve 1 provided in the air bleeding pipe 20
A vacuum pipe provided with an air inflow valve 21 and connected to an air source, and a vacuum pipe provided with a vacuum valve 23 and connected to a vacuum source. 24 in communication with each other.

[0007]

In order to supply sludge from the sludge inflow pipe 6 to the closed tank 1 for filtration and concentration, the air release valve 19, the air inflow valve 21, the vacuum valve 23, and the concentrated sludge discharge valve 13 are closed, and the sludge inflow valve 5, When the filtrate valve 7 and the air release valve 9 are opened and the sludge pump 16 is operated to push the sludge into the sludge concentration section 3, pressure is applied to the sludge stored in the sludge concentration section 3, and the filter element 11 is pressed. Filtered by the filter element 11
The sludge adheres to the outside of the filter and is concentrated, and the filtrate is stored in the liquid collecting section 4 through the inside of the filter element 11.
Spill out of. At this time, the filtrate in the liquid collecting section 4 is kept at HWL. After completion of the filtration and concentration step, the concentrated sludge adhering to the outside of the filter element 11 is peeled off,
Move to the discharge step, but after the filtration and concentration step, the sludge concentration section 3
The sludge inside is not discharged but left as it is, the sludge pump 16 is stopped, and the sludge inflow valve 5, the filtrate valve 7, and the air vent valve 9
Is closed, the vacuum valve 23 and the air bleeding valve 19 are opened, the liquid collecting part 4 is brought into a vacuum state, and the level of the filtrate is kept at HWL. Next, when the vacuum valve 23 is closed and the air vent valve 9 is opened, the vacuum state in the liquid collecting chamber 4 is broken, and the filtrate in the liquid collecting chamber 4 flows back into the filter element 11 and the filter element 11 At the same time as the concentrated sludge adhering to the outside is removed, the filter element 11 is washed. At this time, when the element 11 is of an elastic type, the filter element 11 expands, so that the separation of the concentrated sludge becomes more effective by physical force. The peeled concentrated sludge settles in the lower part of the closed tank (1), and the sludge pump 16 is operated again to start the filtration step.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 and 2. In FIG. 1, a sludge thickening section 3 and a liquid collecting section 4 are partitioned by a partition plate 2 in a closed tank 1. A plurality of tubular filter elements 11 having one end opened and the other end closed are disposed hanging on the partition plate 2, and the open ends thereof are communicated with the liquid collecting section 4.
A filtrate outflow pipe 8 having a filtrate valve 7 is provided in the liquid collecting section 4, and sludge is supplied from a sludge inflow pipe 6 having a sludge inflow valve 5 into the sludge enrichment section 3 of the closed tank 1. An apparatus for draining the filtrate permeated into the filter element 11 to the outside of the tank via the liquid collecting part 4 to filter and concentrate the sludge, comprising: an air vent pipe 20 communicating with the upper part inside the sludge concentrating part 3;
, An air bleeding pipe 10 provided with the air bleeding valve 9 in the liquid collecting part 4, an air pipe 22 provided with an air inflow valve 21 and connected to an air source, and a vacuum valve 23.
And a sludge filtration / concentration apparatus configured to communicate with a vacuum tube 24 connected to a vacuum source.

As the filter element 11,
A known support such as a perforated tube with a filter cloth wrapped around it, a hollow fiber, a porous ceramics filter tube, a porous resin filter tube, or the like can be used, but an elastic support such as a coil spring can be used. It is preferable to use a filter element 11 having a stretchable structure supporting a cylindrical filter cloth.
In addition, as shown in FIG.
The suction side is connected to the discharge side of a sludge pump 16 connected to the raw sludge storage tank 15, and the raw sludge stored in the raw sludge storage tank 15 is passed through the sludge inflow pipe 6 by the sludge pump 16 and the sludge concentration section 3 in the closed tank 1 When the raw sludge is injected by the sludge pump 16 or the pressure of the liquid collecting part 4 is reduced, sludge adheres to the outside of the filter element 11 due to the differential pressure generated inside and outside the filter element 11. While being concentrated, the filtrate permeates into the filter element 11, is collected in the liquid collecting part 4, and flows out from the filtrate outlet pipe 8.

The concentrated sludge is supplied to the filter element 1
As described above, it is preferable that the liquid collecting chamber 4 is evacuated and then peeled off when the liquid is collected from the substrate 1. Since it is possible to perform uniform peeling, it is also possible to release the air vent valve 19 without opening the vacuum state. At this time, the operation of the vacuum valve 23 and the air vent valve 9 is not necessary and is kept closed. Further, after the above-described vacuum break of the liquid collecting chamber 4, the air vent valve 9 is closed, the air inflow valve 21 is opened, and pressurized air or pressure water is introduced into the liquid collecting part 4 to pressurize the filtrate flowing backward. If it does, stripping of concentrated sludge will be performed more effectively. When the air inflow valve 21 of the air pipe 22 is opened while the vacuum valve 23 is closed and the air vent valve 9 is closed, the pressure is changed from the reduced pressure state to the pressurized state at a stretch, and the filtrate is rapidly injected into the filter element 11. The most efficient separation of concentrated sludge and the filter element 1
Washing 1 is performed.

The stripped concentrated sludge is supplied to the concentrated sludge discharge section 1
The sludge that has once concentrated is sedimented in the non-concentrated sludge without breaking its shape, and flows back into the filter element 11 so that the amount of filtrate flowing out is only a small amount. Is slightly diluted, and the concentrated sludge is hardly diluted.
The concentrated sludge that has been deposited and deposited at the bottom of 2 is discharged from the concentrated sludge discharge pipe 14 by opening the concentrated sludge discharge valve 13 and possibly using a pump. As a pump for discharging the concentrated sludge, a snake pump or another positive displacement pump may be used. In this concentrated sludge stripping and discharging process, the concentration of sludge discharged from the concentrated sludge discharge pipe 14 is measured, and when the concentration falls below a predetermined concentration or after a lapse of a predetermined time, the process is switched to the filtration concentration process again. It is convenient if the discharged sludge concentration is automatically measured to enable automatic stop and switching. Thus, the filtration and concentration step is performed again. However, the inside of the sludge concentration section 3 is almost full of the small amount of filtrate used for stripping the concentrated sludge and the unconcentrated sludge, and the sludge is filled as in the conventional case. Almost no steps are required.

In order to discharge the concentrated sludge that has settled and settled at the bottom of the concentrated sludge discharge section 12 that has been separated, the concentrated sludge of the filter element 11 is separated and washed, and then the separated concentrated sludge is discharged. Instead, the valves are opened and closed as they are, and the sludge pump 16 is operated to restart the filtration and concentration step. At this time, pressure is applied to the sludge thickening section 3 and filtration and concentration are performed. At the same time, the concentrated sludge discharge valve 13 is opened to settle the sedimentation using the pressure in the sludge thickening section 3 or a pump as necessary. The accumulated sludge accumulated can be continuously discharged for a predetermined time so that the time required for one cycle can be further shortened. In this case, it is preferable that the discharge of the concentrated sludge can be automatically stopped when the discharged sludge concentration becomes equal to or lower than the predetermined concentration. In addition, in order to prevent the function deterioration due to the adhesion of the oxide to the filter element 11 as described above, it is necessary to prevent the filter element 11 from coming into contact with air in the concentrated sludge peeling and discharging step. It is preferable to set the volume of the liquid collecting section 4 so that the filtrate during the process always remains in the liquid collecting section 4. According to many experimental results, the amount of filtrate required for stripping concentrated sludge is 2 to 2.
15l / m ² - is about elements, also the air pressure in the case of air pressure combination was optimally about 0.5~2kgf / cm ^2.

Further, as a means for preventing the filter element 11 from coming into contact with air, as shown in FIG. 3, a water level gauge 25 is provided in the liquid collecting section 4, and the water level of the filtrate is set in the liquid collecting section 4.
It is preferable that the air inflow valve 21 be closed at the inner LWL so that the air can be opened to the atmosphere. Further, as shown in FIG. 4, an elastic diaphragm 26 may be stretched over the liquid collecting part 4 to form an air chamber 27, and air of a predetermined pressure may be introduced into the air chamber 27 from an air source. At that time, the air vent tube 10 is branched off from the filtrate outflow tube 8.

Next, when the apparatus of the present invention is used, an experimental comparison with the conventional example shows that sludge having the properties shown in Table 1 discharged from the sedimentation basin of the N water treatment plant as raw sludge is obtained as follows.
Filtration and concentration were performed using the filtration and concentration devices shown in Table-2.

[0015]

[Table 1]

[0016]

[Table 2]

Table 3 shows each process time per cycle.
It was set as 3.

[0018]

[Table 3]

Table 4 shows the results of the above experiments.

[0020]

[Table 4]

Next, when the concentrated sludge was discharged during the filtration and concentration step, the process times per cycle were as shown in Table 5, and the experimental results were as shown in Table 6.

[0022]

[Table 5]

[0023]

[Table 6]

As described above, in the present invention, the concentrated sludge is appropriately separated without removing the unconcentrated sludge from the apparatus to the raw sludge storage tank when separating and discharging the concentrated sludge. The capacity of the sludge storage tank is much smaller than before, and there is no need for a sludge filling step to fill the raw sludge into the device during filtration and concentration, and almost continuous treatment is achieved by discharging the concentrated sludge during the filtration and concentration step. Possible, and the filtration speed is greatly improved. Furthermore, when returning the non-condensed sludge in the conventional method, the thickened sludge must be thickened so that the vacuum does not cause separation or cracking of the thickened sludge on the filter element, and the filtration speed becomes extremely poor. Since the present invention does not return unconcentrated sludge, it can be operated even if the thickness of the concentrated sludge is small, and the filtration speed can be further increased.

[0025]

According to the present invention, the concentrated sludge of the filter can be uniformly and efficiently separated from the filter by the filtrate without discharging the unconcentrated sludge in the conventional closed tank, which has been conventionally required. Significantly shortens the time required for filtration, reduces the actual filtration time, reduces power consumption and other running costs, reduces the capacity of the attached sludge storage tank, and reduces the vacuum when removing the concentrated sludge from the cylindrical filter element. After the state, the sludge thickening section is opened to the atmosphere, and furthermore, the combined use of pressure gas or pressure water enables more effective peeling, thereby avoiding oxidation of the concentrated sludge attached to the element by air. In addition, the service life of the filter element can be greatly extended, and a remarkable effect can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

FIG. 2 is a system explanatory diagram of one use state of the example of FIG. 1;

FIG. 3 is a partial longitudinal sectional view of another embodiment of the present invention.

FIG. 4 is a partial longitudinal sectional view of still another example of the present invention.

FIG. 5 is a longitudinal sectional view of an example of a conventional filtration and concentration device.

FIG. 6 is an explanatory diagram of a system in one use state of the example of FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Closed tank 2 Partition plate 3 Sludge thickening part 4 Liquid collecting part 5 Sludge inflow valve 6 Sludge inflow pipe 7 Filtrate valve 8 Filtrate outflow pipe 9 Air vent valve 10 Air vent pipe 11 Cylindrical filter element 12 Thickened sludge discharge part 13 Thickened sludge Discharge valve 14 Condensed sludge discharge pipe 15 Raw sludge storage tank 16 Sludge pump 17 Return valve 18 Return pipe 19 Air release valve 20 Air release pipe 21 Air inflow valve 22 Air pipe 23 Vacuum valve 24 Vacuum pipe 25 Water level gauge 26 Diaphragm 27 Air chamber

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Masanori Eto 1-6-27 Konan, Minato-ku, Tokyo Ebara Infilco Co., Ltd. (56) References JP-A-1-288308 (JP, A)

Claims (1)

(57) [Claims] 1. A plurality of cylindrical filters in which a sludge thickening section 3 and a liquid collecting section 4 are partitioned by a partition plate 2 in a closed tank 1, and one end is opened in the sludge thickening section 3 and the other end is closed. Element 1
1 is suspended from a partition plate 2, the open end of which is communicated with a liquid collecting part 4, a filtrate outlet pipe 8 having a filtrate valve 7 is provided in the liquid collecting part 4, and the sludge of the closed tank 1 is provided. Sludge is supplied from the sludge inflow pipe 6 having the sludge inflow valve 5 into the concentration section 3, and the filtrate permeated into the cylindrical filter element 11 is discharged out of the tank through the liquid collection section 4 to filter and concentrate the sludge. An air vent pipe 20 communicating with an upper portion inside the sludge concentrating section 3 and an air vent valve 19 provided in the air vent pipe 20.
The air vent valve 10 provided with the air vent valve 9 is provided, and an air inlet valve 21 is provided, and an air tube 22 connected to an air source and a vacuum tube 24 provided with a vacuum valve 23 and connected to a vacuum source are provided in communication with each other. Sludge filter concentrator.