JPH0523804B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method and apparatus for discharging sludge settled in a sedimentation tank in water purification or wastewater treatment. [Prior Art] Generally, in a sewage clarification device, as shown in FIG.
Using the water head of the settling tank 2, sludge is drained from the sludge drawing pipe 4 to the thickening tank X by operating a sludge valve 5. When discharging sludge from a sedimentation tank,
As described in Publication No. 37848, there are (1) a method using a mechanical discharge device powered by power, (2) an extrusion method using water pressure, and (3) a method of emptying the tank and washing it out. ) and (2) continuous sludge removal methods are reasonable. In any case, in this type of sludge removal operation, it is important to discharge the entire amount of highly concentrated sludge without mixing it with the supernatant liquid. [Problems to be Solved by the Invention] However, in the conventional sludge drainage system, as shown in FIGS. When the sludge drain valve D of the drain pipe C connected to is opened, initially as shown in Fig. 7,
Only sludge A is discharged, but as shown in Fig. 8, supernatant liquid B gradually mixes into sludge A, thereby reducing the sludge concentration in the drained liquid and continuing to drain as much as possible. However, if the draining was continued for a long time, only the supernatant liquid would be drained, as shown in Figure 9, and the operation would end. However, this takes a long time to drain the sludge, increases the operating cost of the discharge pump, and, as shown in FIG. 9, the entire amount of sludge cannot be discharged, resulting in sludge remaining in corners and the like. Therefore, the method described in the above-mentioned publication has been proposed, but although it has certain effects, it has drawbacks such as not being reliable. In other words, it is difficult to seal the sliding part between the diaphragm and the pit, and it requires a large amount of power to move up and down the diaphragm that closes the pit, which is 2 to 3 meters long (cross-sectional view). It is difficult to control as there is no means of detection, it is necessary to avoid the discharge pipe that faces into the sludge pit when the partition plate is lowered, and although it is not impossible, there are other drawbacks such as a significant increase in equipment costs as a whole. On the other hand, the present applicant has proposed, in Japanese Patent Application No. 59-62834, that a collecting/discharging bag is provided in a mud collecting pit, the opening of the bag is partitioned off by a partition member, and after this partitioning, the bag is Although we have proposed a technology to shrink the collection/discharge bag, there are drawbacks such as difficulty in operating the partitions and high equipment costs. The present invention solves the above-mentioned conventional problems at once, and its purpose is to produce settled sludge that can reduce the amount of supernatant liquid mixed in and quickly and easily discharge the entire amount of high-concentration sludge. An object of the present invention is to provide a discharge method and device. [Means for Solving the Problems] The method of the present invention for solving the above-mentioned problems includes disposing a collection/drainage bag which has an open top and is made of a substantially flexible material in the sediment collection pit of the settling tank. , a sludge drawing pipe communicating with the outside of the tank is provided at the bottom of the collection/discharge bag, and with respect to the height direction position of the collection/discharge bag, a contraction means for reducing the diameter of the collection/discharge bag is provided at least at a position near the opening; The present invention is characterized in that the settled sludge inside the bag is discharged through the sludge drawing pipe by shrinking the diameter of the collection/discharge bag. Further, the device of the present invention is substantially made of a flexible material, has an open upper part, the opening edge is fixed in a sealed state to the inner wall of the mud collecting pit, or the vicinity above the mud collecting pit. The bag, a sludge drawing pipe that communicates the bottom of the bag with the outside of the tank, and a sludge drawing pipe that are arranged at intervals in the height direction of the bag, reduce the diameter of the bag, and operate from above. It is characterized by comprising a plurality of contraction means that sequentially move downward. [Function] In the present invention, a collection/discharge bag is provided in the sludge collection pit, and settled sludge is stored inside the bag. In order to discharge this settled sludge to the outside through a sludge extraction (discharge) pipe, a shrinking means such as an annular bag is provided between the collection/discharge bag and the inner wall of the sludge collection pit. The bag body is provided with means for supplying and discharging fluid such as water. Now, when water is forced into the bag, the bag expands, and since the bag is regulated at the back by the inner wall of the dirt collection pit, the bag contracts as it expands. This contraction causes the collection bag to discharge the sludge inside it through the sludge withdrawal pipe. By the way, if the diameter of the collection/drainage bag does not shrink from the top to the bottom, for example, if the lower part contracts in the initial stage, the sludge in the collection/drainage bag will be pushed up through the opening into the clarified liquid above. Therefore,
In the present invention, at least the bag body is provided near the opening edge of the collection/discharge bag, and the diameter of the bag is first contracted from the upper part of the collection/discharge bag. In this case, only one deflation means such as a bag may be used, but if a plurality of deflation means are provided and the operation is delayed sequentially from the top to the bottom, mud can be removed without pushing up. [Specific Examples of the Invention] The present invention will be explained in more detail below with reference to a first specific example shown in FIGS. 1 to 4. 10 is a collection/discharge bag made of a flexible material such as rubber. This bag 10 is provided in the mud collecting pit 1, has an open upper part, and the opening edge is fixed to the inner wall surface of the mud collecting pit 1 in a sealed state by a fixed sealing member 11. 12 is a sludge drawing pipe, which is connected to the discharge port 10a at the bottom of the bag 10. The bag 10 has a fourth discharge port 10a.
As shown in detail in the figure, it is sandwiched between a flange 12a at the end of the drawn pipe 12 and a fixing plate 13 and fixed with bolts 14, and is fixed in position with respect to the drawn pipe 12 (in other words, with respect to the mud collecting pit 1). has been done. A sludge removal control valve 15 is provided in the middle of the sludge drawing pipe 12, and is connected to suction means such as a pump 16. Further, a pressurized water insertion pipe 18 is provided in communication with bag bodies 22A and 22B, which will be described below, which are arranged in the gap 17 between the collection/drainage bag 10 and the mud collection pit 1, and an insertion control valve 19 is provided in the middle thereof. installed. Further, a drain pipe 21 having a drain valve 20 is provided branching from the pressure water insertion pipe 18 . On the other hand, at the upper and lower portions of the gap 17, flexible and annular first and second tubes made of rubber or the like are provided.
Bag bodies 22A and 22B are arranged and fixed to the inner wall of the collection/discharge bag 10 or the mud collection pit 1. Branch pipes 18A and 18B of the pressurized water insertion pipe 18 communicate with these bags 22A and 22B. Switching control valves 18a and 18b are attached to the branch pipes 18A and 18B, respectively. Also, between the gap 17 and the supernatant liquid, there is an introduction valve 23 in the middle.
Communication is possible through a supernatant fluid inlet pipe 24 having a supernatant fluid inlet pipe 24. Furthermore, a cleaning pipe 26 having a cleaning valve 25 is connected to the sludge drawing pipe 12 . In such equipment, when discharging sludge, the sludge discharge control valve 15 is opened when the collection/discharge bag 10 is almost full of sludge. As a result, the water head pressure determined by the liquid level in the settling tank 2 is acting on the sludge, so that pushing pressure is applied to the sludge, and the sludge begins to pass through the sludge extraction pipe 12 and begin to be drained. However, this sludge draining operation only forms the shortest flow path in the sludge, and the sludge outside the flow path does not flow and is not drained. Therefore,
When the sludge control valve 15 is opened, the insertion control valve 19 is opened almost at the same time or with a slight delay, and the switching control valve 18a is also opened, and pressure water higher than the water head pressure is passed through the pressure water insertion pipe 18 and the branch pipe 18A. It is supplied to the first bag body 22A. As a result, as shown in FIG. 2, the first bag body 22A is expanded and the collection/discharge bag 10
The diameter of the upper part of the sludge is reduced, and the sludge contained therein is discharged through the sludge extraction pipe 12. Due to this contraction action, the initial inflow of supernatant liquid into the collection/drainage bag, the suction action by the pump 16 performed as necessary, etc., the lumps of sludge in the collection/drainage bag 10 break down and become stuck to the inner surface of the collection/drainage bag 10. The sludge is discharged as it is peeled off. After that, the switching control valve 18b is also opened, supplying pressurized water to the second bag body 22B, as shown in FIG. Furthermore, sludge is discharged. At this stage, depending on the degree of expansion of each bag 22A, 22B,
Most of the sludge is discharged. In order to further thoroughly drain the sludge, open the introduction valve 23 and introduce the supernatant liquid into the gap 17, and use the water head pressure of the supernatant liquid or a pipe branched from the pressure water insertion pipe 18 ( The bag 10 is deflated by introducing pressurized water at a pressure higher than the water head pressure through the tank (not shown). In this way, the collecting and discharging bag 10 is sequentially squeezed from the top to the bottom, and by completely deflating the collecting and discharging bag 10, the entire amount of sludge can be discharged. When all the sludge has been discharged and the collection/drainage bag 10 no longer contracts, the switching control valve 18 is opened.
a, 18b and the drain valve 20 are opened to drain the pressure water in the gap 17. As a result, the collection/discharge bag 10 expands and returns to its original state. At this time, the sludge extraction pipe 12 can be cleaned by closing the sludge control valve 15, opening the cleaning valve 25, and injecting cleaning water into the sludge extraction pipe 12. In the above example, when applying suction pressure, the head pressure of the settling tank 2, the opening/closing of the sludge control valve 15, and the
Although the suction pressure applying means is constituted by the expansion of 2A and 22B, the suction pressure applying means may be constituted by using the pump 16 together with these or alone. The use of the pump 16 is effective when delivering sludge to a location where the head pressure is higher than the head pressure, or when the suction pressure is insufficient at the head pressure. In the above example, the pressure fluid passing through the insertion tube 18 may be air, particles, or the like. Further, the suction pressure extraction pipe 12 may be installed in communication with the bottom surface of the collection/discharge bag 10 instead of the bottom side portion as in the above example.
Further, in the above example, the collecting/discharging bag 10 is fixed to the drawn pipe 12, but it may be fixed by a suitable metal fitting provided near the drawn pipe 12. By the way, mud drain port 10
If a is not at the bottom, there is a risk of sludge remaining, and if it is at the top, there is a risk of sludge being pushed up when the bag is contracted into the collection/discharge bag 10.
Furthermore, if a part of the collection/discharge bag 10 is not fixed, its contraction will be random, and in extreme cases, there is a risk that it will float up. By the way, as the material for the bags 22A and 22B, in addition to rubber, there may be used a filter cloth with meshes that are impermeable to sludge, plastic, cloth coated with latex, and the like. The bag body is 1
However, in this case, it is necessary to take measures such as changing the wall thickness of the bag so that the upper part of the bag expands first and the lower part expands sequentially. Therefore, it is generally economical and highly reliable to arrange a plurality of bags in the height direction. In the above example, a bag was used as the contraction means, but
Like the aperture mechanism or shutter mechanism of a camera (excluding focal planes), a plurality of vanes may be provided behind the collection/discharge bag to narrow the collection/discharge bag. However, this type of mechanical contraction means is not very desirable due to the space of the sedimentation tank's sludge collecting pit, and the practical method is to use a bag body. On the other hand, it is also possible to use the contraction means 30 shown in FIG. That is, pinch rods 31 and 32 are fixed to opposite sides of the upper edge of the collection/discharge bag 10, and a guide rod 3 with one end thereof stretched over the inner wall of the pit 1.
3, and a nut 3 at their other end.
4 and 35 are fixed, and these nuts 34 and 35 are screwed into a moving screw rod 36 whose both ends are reverse threaded, and this screw rod 36 is rotated by the output rotation of the motor 37. , the opening of the collection/discharge bag 10 is opened and closed. In addition, screw rod 3
The tip of the motor 3 is loosely fitted into the inner wall of the pit 1.
7 is fixed to the outer wall of the pit 1. Further, a plurality of contraction means may be provided in the height direction of the collection/discharge bag 10. In this case, contraction is performed in order from the top to the bottom. Furthermore, in this example, as the bag contracts, supernatant liquid gets mixed in between the inner wall of the pit 1 and the bag 10, but this can be easily discharged during re-expansion. In this example, it is possible to completely close the opening edge of the collection/drainage bag, so it is possible to drain the sludge without diluting it with supernatant liquid.
Even in the case of incomplete sealing as shown in the figure, efficient and complete sludge removal is possible by using the water head pressure with or without the drawing operation via the drawing pipe 12. [Example] A sludge collection pit with a capacity of 90 was constructed in the manner shown in FIGS. 1 and 4, and when drinking water sludge was drained, the results shown in Table 1 were obtained. The table also shows the results of the conventional method shown in FIGS. 7 to 9.

〔Effect of the invention〕

As described above, according to the present invention, almost the entire amount of sludge can be discharged quickly and operationally without mixing the supernatant liquid or pushing up the sludge. Furthermore, the device configuration is simple, maintenance is easy, and equipment costs are low.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the main parts of the device of the present invention, Figure 2
3 and 3 are schematic diagrams sequentially showing the sludge removal process, FIG. 4 is a cross-sectional view showing an example of fixing the collecting and discharging bag, FIG. 5 is a schematic perspective view showing an example of another contraction means, and FIG. A schematic diagram of the entire thickening and sedimentation equipment, and FIGS. 7 to 9 are schematic diagrams sequentially showing the conventional sludge removal process. 1... Sludge collection pit, 2... Sedimentation tank, 10... Collection/discharge bag, 10a... Discharge port, 11... Fixed seal, 12... Sludge extraction pipe, 15... Sludge removal control valve,
16... Pump, 17... Gap, 18... Pressure water insertion pipe, 19... Insertion control valve, 22A, 22B...
Bag body (deflation means).

Claims (1)

[Scope of Claims] 1. A collection/drainage bag which is open at the top and made of a substantially flexible material is disposed in the sludge collection pit of the settling tank, and a sludge withdrawal pipe communicating with the outside of the tank is provided at the bottom of the collection/drainage bag. established,
A contraction means for reducing the diameter of the collection/discharge bag is provided at least near the opening in the height direction of the collection/discharge bag, and the settled sludge inside the bag is pulled out by the contraction of the diameter of the collection/discharge bag by the contraction means. A method for discharging settled sludge characterized by discharging it through a pipe. 2. The deflation means includes a substantially horizontal annular bag disposed between the collection/discharge bag and the inner wall surface of the dirt collection pit, and an inflation mechanism configured to feed fluid into the bag in order to inflate the bag. A method for discharging settled sludge according to claim 1, comprising means. 3. A collection/drainage bag which is substantially made of a flexible material, has an open upper part, and whose opening edge is fixed in a sealed state to the inner wall of the mud collection pit or near the upper side thereof, and which is disposed within the mud collection pit; A sludge drawing pipe that communicates the bottom of the tank with the outside of the tank is arranged at intervals in the height direction of the collection bag, and the diameter of the collection bag is reduced.
A device for discharging settled sludge, comprising: a plurality of contraction means whose operating times sequentially shift from the upper side to the lower side.