KR100329318B1 - Sludge Dehydration Apparatus and Sludge Dehydration System Using the Same - Google Patents

Abstract

The present invention relates to a sludge dewatering apparatus for separating water from sludge containing a large amount of water and a sludge dewatering system using the same.

The sludge dewatering device of the present invention is a flocculating device for adding flocculant into the sludge to form flocs, a solid-liquid separation device for condensing the sludge that has been flocculated by the flocculating device, and a sludge concentrated by the solid-liquid separation device for water permeability. A belt press dehydrator for pressing and dewatering between the filter belts is provided.

The sludge dewatering system of the present invention includes a reaction tank, a sedimentation basin in which the reaction tank is in communication, a flocculation apparatus for adding flocculant to the sludge introduced from the sedimentation basin to form flocs, and a sludge flocculated by the flocculation apparatus. A solid-liquid separator to concentrate and a belt press dehydrator which pressurizes the sludge concentrated by the solid-liquid separator between a water-permeable filter belt and dewater-processes.

The present invention can use a simpler belt press dehydrator that is smaller than the conventional one, and can reduce the number of filtration belts and rollers of an expensive belt press dehydrator, thereby reducing the installation cost and reducing the running cost and maintenance cost. Can be.

Description

Sludge Dehydration Apparatus and Sludge Dehydration System Using the Same}

The present invention relates to a sludge dewatering apparatus for separating water from sludge containing a large amount of water and a sludge dewatering system using the same.

Sludge containing a large amount of water is discharged from general households, food processing plants, pig farms or hotels. Such sludge is dewatered by a sludge treatment apparatus after the water treatment.

Fig. 6 is a schematic explanatory view showing an entire sludge treatment apparatus having a conventional dewatering apparatus. Sludge discharged from a general household or the like flows into a reaction tank 31A called an aeration tank, where organic matter contained in the sludge is decomposed by microorganisms. In this reaction tank 31A, sludge is transferred to the settling basin 33A via the communication pipe 32A, and the clear water floated above is discharged to a river or the like. The sludge settled here is conveyed to the concentration tank 35A by the pump 34A. And the sludge settled in this concentration tank 35A is transferred to the storage tank 37A by the pump 36A, and it is stored here. Clear water floated on the sedimentation basin 33A and the concentration tank 35A separated from the sludge is discharged to a river or the like. The water content of the sludge transferred from the reaction tank 31A to the settling basin 33A is usually about 99.2 to 99.7% by weight, and the water content of the sludge concentrated in the concentration tank 35A is usually about 97.5 to 98.5% by weight.

The sludge stored in the storage tank 37A is transferred to the mixing tank 40A of the flocking device 39A by the pump 38A. A flocculant is added to the sludge in this mixing tank 40A as shown by the arrow D, and this sludge and aggregator are stirred and mixed by the stirrer 41A which rotates, and many flocs are formed by this. In this way, the flocculated sludge is dewatered by the belt press dehydrator 42A. 43 A of sludge dewatering apparatuses are comprised by the belt press dehydrator 42A and the flocculation apparatus 39A.

The sludge dewatered by the belt press dehydrator 42A forms a cake shape, and the water content of this dewatered cake E is usually about 80 to 83% by weight.

Most of the sludge flowing into the reaction tank 31A is water, and in order to make such sludge a sludge cake having a water content of 80 to 83% by weight, it is necessary to keep the sludge moisture content up to the mixing tank 40A as low as possible. For this reason, conventionally, in addition to the reaction tank 31A and the settling basin 33A, a concentration tank 35A or a storage tank 37A is provided, and the sludge is passed through these tanks 35A and 37A so as to lower its water content. there was. However, the installation of such a concentration tank 35A or a storage tank 37A requires an excessive construction cost.

In addition, since sludge flows into the reaction tank 31A and then flows into the storage tank 37A, the sludge goes through a number of processes such as sedimentation, concentration, and storage, so that the sludge reaches the flocking device 39A from the reaction tank 31A. It required a lot of time, and usually a processing time of about one week was required. This caused the sludge to decay in the meantime and cause odors.

In addition, even when the concentration tank 35A or the storage tank 37A as described above is used, the water content of the sludge conveyed to the belt press dehydrator 42A is 97.5 to 98.5%, and the sludge still contains a large amount of water. For this reason, it was necessary to use the complicated and large apparatus as illustrated in FIG. 6 as the belt press dehydrator 42A.

7 is an enlarged view of the belt press dehydrator 42A, wherein the belt press dehydrator 42A shown here is first filtration wound around a pair of rollers 44A and 45A and driven to travel in the direction of an arrow F. FIG. Similarly to the second filter belt 52A wound around the belt 46A and the plurality of rollers 47A, 48A, 49A, 50A, 51A and driven in the direction of the arrow F1, the plurality of rollers 53A, 49A, A third filter belt 56A is wound around 50A, 54A, 55A and driven to travel in the direction of an arrow F2. The sludge flowing out of the mixing tank 40A of the flocculating device 39A falls on the first filtration belt 46A as shown by arrow I, and the sludge is then shown by arrow H1. In the same manner, the process proceeds to the second filter belt 52A, and then passes between the second filter belt 52A and the third filter belt 56A, as shown by arrows H2, H3, and H4. In this way, when the sludge passes between the filter belts, it is pressurized by the filter belt to squeeze out moisture and finally scraped off by the scraper 57A from the third filter belt 56A so as to form a sludge cake (E). Removed.

As mentioned above, since the conventionally large and complicated belt press dehydrator 42A needed to be used, the fault which the cost of the sludge dehydration apparatus 43A raises was unavoidable.

In addition, since the solids of the sludge remain in the water separated by the belt press dehydrator 42A, that is, the concentrate W, the concentrate W is returned to the reaction tank 31A as shown in FIG. Here it is mixed with untreated sludge and processed again. At that time, as described above, the sludge that is transferred from the storage tank 37A to the flocking device 39A is decayed. Therefore, the concentrated liquid W separated by the belt press dehydrator 42A is also decaying organic matter. When the concentrated liquid W is returned to the reaction tank 31A for treatment, sludge from the sedimentation basin 33A is inhibited by the decaying filamentous fungi contained therein, making it difficult to separate water and sludge. For this reason, the fault which the precipitation efficiency falls from the settling basin 33A, and the efficiency of the whole water treatment falls significantly cannot be avoided.

As shown in Fig. 8, a sludge treatment apparatus using a centrifugal concentrator 58A instead of the concentration tank 35A shown in Fig. 6 is also known. By using such a concentrator 58A, the water content of the sludge discharged therefrom can be reduced to about 93.5 to 94.5%, so that it is possible to alleviate the drawbacks of the apparatus shown in FIG.

However, when the centrifugal concentrator 58A is used, in addition to the flocculant addition to the mixing tank 40A, it is necessary to add flocculant to the sludge before being treated with the concentrator 58A as shown by arrow J in FIG. have. Since the flocculant must be added twice in this way, the disadvantage that the sludge treatment cost increases is inevitable.

An object of the present invention is to provide a sludge dewatering apparatus capable of eliminating all the above-mentioned conventional drawbacks.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic explanatory diagram showing an entire sludge treatment system including a sludge dewatering apparatus according to an embodiment of the present invention.

2 is a longitudinal sectional view of a solid-liquid separation device;

3 is a perspective view showing one fixing ring, one movable ring, and a spacer;

4 is a partially exploded perspective view of the solid-liquid separation device;

5 is a partial cross-sectional view of a solid-liquid separation device.

6 is a schematic illustration of a sludge treatment apparatus having a conventional sludge dewatering apparatus.

7 is an enlarged view of the belt press dehydrator shown in FIG.

8 is a schematic explanatory view showing another example of a conventional sludge treatment apparatus.

<Explanation of symbols for main parts of the drawings>

6: fixed ring

16: screw conveyor

30: movable ring

39: flocking device

42: Belt Press Dehydrator

43: sludge dewatering device

59: solid-liquid separation device

60: roller

61: roller

62: filtration belt

63: roller

64: roller

65: filtration belt

66: scraper

D4: Outer Diameter

D5: inner diameter

In order to achieve the above object, the present invention provides a flocculation device for adding flocculant to the sludge to form flocs, a solid-liquid separation device for condensing the sludge flocculated by the flocculation device, and a concentration of the solid-liquid separation device. And a belt press dehydrator configured to pressurize the sludge between the water-permeable filter belts to dehydrate the solids, and the solid-liquid separator is provided with a plurality of fixing rings arranged in the axial direction with a gap therebetween and fixed integrally with each other. A movable ring disposed in a movable state at least radially in a gap between the rings, and a plurality of fixed rings and a screw conveyor disposed in the inside of the movable ring to be driven in rotation, wherein an inner diameter of the movable ring is The sludge dewatering apparatus which is set smaller than the outer diameter is proposed.

At this time, the belt press dehydrator is provided with an endless first filter belt wound and driven by a pair of rollers, and disposed opposite to the first filter belt, and further wound and driven by a pair of rollers. It is advantageous to have an endless second filtration belt for pressurizing the sludge between the first filtration belt and a scraper for separating the pressurized sludge from the second filtration belt.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail based on drawing.

1 is a schematic explanatory view showing an entire sludge treatment apparatus including a sludge dewatering apparatus according to an embodiment of the present invention. The sludge treatment apparatus shown here does not have the concentration tank 35A, the storage tank 37A, and the centrifugal concentrator 58A shown in Figs. 6 and 8; instead, the flocculator 39 and the belt press are shown. The solid-liquid separator 59 is arrange | positioned between the dehydrator 42, and the belt press dehydrator 42 has a simpler structure than the dehydrator 42A shown in FIGS. The sludge dewatering device 43 is constituted by the belt press dehydrator 42, the solid-liquid separation device 59, and the flocking device 39.

Also in the sludge treatment apparatus shown in FIG. 1, sludge discharged from a general household, a food processing plant, a pig farm, a hotel, or the like flows into the reaction tank 31, where organic matter in the sludge is decomposed by microorganisms, and the remaining sludge Is transported to the sedimentation basin 33 through the communication pipe 32, and the clear water thereon is discharged to a river or the like, and the sludge deposited therefrom is conveyed to the sludge treatment apparatus by the pump 34.

Up to now, there is no change from the conventional sludge treatment apparatus.

Unlike the conventional sludge settled in the settling basin 33, the pump 34 is moved directly to the mixing tank 40 of the flocculating device 39, a flocculant is added to the sludge as indicated by the arrow D, The sludge in the mixing tank 40 and the flocculant are stirred and mixed by the rotating stirrer 41. As a result, a large number of flocs are formed.

The flocified sludge as described above is dewatered and concentrated by the solid-liquid separator 59, and then dewatered further by the belt press dehydrator 42 to form the dewatered cake E.

As described in detail later, the solid-liquid separation device 59 has the same basic configuration as the solid-liquid separation device according to Japanese Patent No. 1987317, Japanese Patent No. 2826990, or Japanese Patent No. 2826991. According to such a solid-liquid separation device, the water and solid content of the sludge can be separated efficiently in a short time, and the sludge moisture content after concentration can be lowered to 90% by weight, for example.

In the sludge treatment apparatus shown in FIG. 1, the solid-liquid separation device 59 described above is used, whereby the water content of the sludge can be greatly lowered, and thus the concentration tank 35A required in the sludge treatment apparatus shown in FIG. ) And the storage tank 37A do not need to be used. For this reason, the cost of a sludge processing apparatus can be reduced significantly.

In addition, since it is not necessary to use the centrifugal concentrator 58A used for the conventional sludge treatment apparatus shown in FIG. 8, it is only necessary to supply a flocculant to a flocculation apparatus, and the cost required for sludge processing can be reduced.

In addition, since the water content of the sludge can be greatly reduced by the solid-liquid separation device 59, as described above, by using only two filter belts for the belt press dehydrator 42, it is possible to use a device having a simple structure and low cost. Do. The belt press dehydrator 42 illustrated in FIG. 1 includes an endless first filter belt 62 wound around a pair of rollers 60 and 61 and driven in an arrow K direction, and the first filter belt ( It is disposed opposite to 62, and is wound around a pair of rollers (63, 64) driving while driving in the direction of the arrow L, the endless second filter belt (2) to sandwich the sludge between the first filter belt ( 65) and a scraper 66 for separating the sludge from the second filter belt 65. The first and second filter belts 62, 65 are made of a flexible sheet member having water permeability, for example, a filter cloth.

As will be described later, the sludge concentrated by the solid-liquid separator 59 falls on the second filter belt 65 as shown by the arrow M, is placed on the filter belt 65, and conveyed in the traveling direction. . At this time, the sludge is sandwiched between the first and second filter belts 62 and 65 and pressed to squeeze out moisture from the sludge. The concentrate W separated from the sludge falls down through the filter belt. The sludge after being squeezed and squeezed out water is separated from the second filter belt 65 by the scraper 66, and becomes a sludge cake E and falls downward. The water content of the sludge cake E at this time is about 76 to 80% by weight.

As described above, a belt press dehydrator 42 having a low number of belts and rollers and a simple structure and low cost is used, and furthermore, the sludge moisture content before the dewatering treatment by the belt press dehydrator 42 is carried out. ), The sludge cake E having a desired moisture content can be obtained only by using the belt press dehydrator 42 having a simple structure.

In addition, the sludge treatment apparatus shown in FIG. 1 is not provided with a concentration tank and a storage tank, and the sludge precipitated in the sedimentation basin 33 is moved to the mixing tank 40 of the flocking apparatus 39 in place. Since the dewatering treatment can be performed easily, the sludge in which the activation before the waste is maintained can be dewatered. For this reason, generation | occurrence | production of an abnormal smell can be suppressed effectively.

By the solid-liquid separator 59 and the belt press dehydrator 42, the concentrated liquids W and W1 separated from the sludge, respectively, are returned to the reaction tank 31 for further treatment, so that the organic matter in the concentrated liquid is not destroyed. When the concentrated liquid is returned to the reaction tank 31 and treated, it is possible to prevent inconvenience that sludge is difficult to settle in the sedimentation basin 33, so that sludge treatment can be efficiently performed.

In addition, the water content of the sludge generated in the reaction tank 31 is usually about 99.7 to 99.8% by weight, the sludge containing a large amount of water, as shown by the dotted line in Fig. Instead of passing through the settling basin 33 through the bypass means, it may be bypassed directly to the mixing tank 40 of the flocking device 39 to dehydrate it. Even with such sludge having a high water content, the sludge can be efficiently concentrated by the solid-liquid separation device 59, and dewatered by the belt press dehydrator 42, for example, a water content sludge of about 76 to 80% by weight. Cake E can be obtained. By reducing the facilities of the settling basin 33 in this manner, the configuration of the sludge treatment apparatus can be further simplified, and the cost thereof can be reduced.

Next, the specific structural example and the effect | action of the solid-liquid separation apparatus 59 are made clear with reference to FIGS.

The solid-liquid separation device 59 shown in FIG. 2 has a casing 1 having a hollow inside, and the sludge flowing out from the mixing tank 40 of the flocculating device 39 shown in FIG. An inlet 2 is formed, and similarly, an outlet 3 through which dewatered and concentrated sludge is discharged is formed at the lower right. In addition, a discharge port 4 through which water separated from the sludge flows is formed in the lower portion of the center of the casing 1, and a solid-liquid separator 5 disposed in a substantially horizontal state is provided in the center of the casing 1.

The sludge introduced into the casing 1 from the inlet 2 is passed through the solid-liquid separator 5, and the water separated there flows down from the drain port 4, and the concentrated sludge is discharged from the outlet 3. Discharged.

The solid-liquid separator 5 has a plurality of retaining rings 6 as shown in Fig. 3, and these retaining rings 6 are arranged concentrically as shown in Figs. The whole is roughly cylindrical. A spacer 9 is sandwiched between each of the fixing rings 6, and a bolt 10 is inserted into the hole 8 and the spacer 9 formed in the ear portion 6a of each of the fixing rings 6. In this example four bolts 10 are used, which are arranged on the same circumference. As shown in FIG. 2, the end of each bolt 10 is fixed to the support plates 11 and 12 fixed to the casing 1 by the nut 12.

In this way, the plurality of fixing rings 6 are arranged in the axial direction with a predetermined gap from each other by the spacer 9, and are integrally fixed to each other by the plurality of bolts 10 and the nuts, and the casing ( It is supported so as not to move relative to 1). A projection such as a spacer 9 may be integrally attached to each of the fixing rings 6 to thereby form a gap between the fixing rings 6.

The movable ring 30 is arrange | positioned in the clearance gap between each stationary ring 6, respectively, as shown to FIG. As shown in Fig. 5, the thickness T of each movable ring 30 is set smaller than the gap width G between the respective fixing rings (T <G), and the end face of each fixing ring 6 The predetermined microgap g is formed between the end surfaces of the movable ring 30 which opposes this. For example, when the gap width G is set to 6 mm and the thickness T of the movable ring 30 is set to 5 mm, each microgap g therebetween becomes 0.5 mm. In addition, the outer diameter of the movable ring (30) (D ₁₎ is smaller than the diameter (D ₂₎ of the circle (C) (Fig. 2) formed by the inner surface of the four spacer 9 is positioned around that, furthermore than the inner diameter (D ₃₎ of each retaining ring (6) it is set larger. By this structure, each movable ring 30 is movable in the radial direction, without deviating from between each fixed ring 6, and also the rotation around a center axis is attained. Thus, the movable ring 30 is arrange | positioned so that a movement in at least the radial direction is possible in the clearance gap between the stationary rings.

In addition, in FIG.2 and FIG.4, about the fixed ring and the movable ring of the center part of the cylindrical member formed by the many fixed ring 6 and the movable ring 30, only the external shape is shown by the dashed line.

The space S is partitioned inside the cylindrical body formed of the plurality of stationary rings 6 and the movable ring 30 as shown in Figs. 4 and 5, but the screw conveyor 16 is provided in this space S. It arrange | positions, The shaft part 13 of each edge part of this conveyor 16 is rotatably supported by the bearings 14 and 15 by the support plates 11 and 12 as shown in FIG.

As mentioned above, the screw conveyor 16 rotatably arrange | positioned inside the stationary ring 6 and the movable ring 30 is drive-connected to the gear motor 17 supported by the casing 1 at one end. . The gear motor 17 constitutes an example of the configuration of the drive means for rotationally driving the screw conveyor.

Both support plates 11 and 12 fixed to the casing 1 are suitable for positions corresponding to the inner space S of the plurality of fixed rings 6 and the plurality of movable rings 30, as shown in FIG. A number of through holes 22 are formed, respectively.

The outer diameter (D4) of the screw conveyor 16, as shown in Figure 5 is set to a slightly smaller size than the internal diameter (D ₃₎ of the retaining ring (6) so that rotation is not inhibited. In addition, the inner diameter D ₅ of the movable ring 30 is set smaller than the outer diameter D ₄ of the screw conveyor 16.

Next, the operation of the solid-liquid separation device 59 will be described in detail.

Flocked sludge flowing out of the mixing tank 40 shown in FIG. 1 flows from the inlet port 2 into the front chamber 1a in the casing 1 through a conduit not shown. The sludge introduced into the front chamber 1a of the casing 1 flows into the internal space S of the fixed ring 6 and the movable ring 30 from the through hole 22 of the support plate 11. At this time, the screw conveyor 16 is driven to rotate about the center axis of the screw conveyor 16 by the gear motor 17, thereby moving the sludge solid-liquid separator 5 from the left side to the right side in FIG. Move. During this movement, the water in the sludge flows out through the microgap g between each stationary ring 6 and the movable ring 30, and this filtrate W ₁ drains the casing 1 drain 4. Is discharged downwards. In this way, the concentrated sludge remains in the internal space S of the solid-liquid separation part 5, which is conveyed by the screw conveyor 16 to the rear of the casing 1 through the through-hole 22 of the support 12. It is conveyed to the chamber 1b, and then discharged out of the casing from the outlet port 3 (arrow Q), and falls on the second filtration belt 65 of the belt press dehydrator 42 shown in FIG.

As described above, the sludge is supplied to the internal space S of the fixed ring 6 and the movable ring 30, and the screw conveyor 16 disposed in the space S is rotated to convey the sludge. By increasing the pressure of the internal space S, the moisture in the sludge is discharged to the outside through the micro gap g between each of the fixed ring 6 and the movable ring 30, so that the solid-liquid separation efficiency can be increased and the casing ( 1) The water content of the sludge discharged outside can be reduced to about 90% by weight as described above.

Further, the movable ring 30 is arranged between each retaining ring (6) is movable at least in the radial direction and, in addition the inner diameter of the movable ring 30 (D ₅₎ is a screw conveyor 31 is unexpected minor diameter ( Since it is set smaller than D ₄ ), each movable ring 30 is pushed by the screw conveyor 16 by the rotation of the screw conveyor 16 and actively operates in the radial direction thereof. In FIG. 5, reference numeral P denotes a contact point between the inner circumferential surface of the movable ring 30 and the screw blade edge of the screw conveyor 16. In FIG.

In this way, by the rotation of the screw conveyor 16, each movable ring 30 receives an external force from the screw conveyor 16 and actively moves relative to the fixed ring 6 in a direction substantially parallel thereto. Since each movable ring 30 performs such a movement, even if a solid content enters the microgap g between each movable ring 30 and the stationary ring 6, it is discharged out of the gap g very efficiently, The blockage can be effectively prevented.

As mentioned above, although an example of the solid-liquid separation apparatus was made clear, this solid-liquid separation apparatus can also be variously changed and comprised. For example, as described in Japanese Patent Nos. 2826990 and 2826991, a plurality of screw conveyors are divided into a plurality of solid-liquid separators, and each of the screw conveyors is driven by a separate motor. In addition, various modifications are possible, such as separately collecting the filtrate separated from each solid-liquid separator.

As will be understood from the foregoing, the sludge dewatering device 43 of the present example has a flocculating device 39 which adds a flocculant to the sludge to form flocs, and sludge flocculated by the flocculating device 39. And a belt press dehydrator 42 for pressurizing and dehydrating the sludge concentrated by the solid-liquid separation device 59 between the water-permeable filter belts 61 and 65. The solid-liquid separation device 59 is arranged in the axial direction at intervals from each other, and is arranged in a movable state at least in the radial direction in the gap between the plurality of fixed rings 6 and each fixed ring 6 fixed integrally. And a plurality of stationary rings 6 and a screw conveyor 16 which is rotationally driven disposed in the movable ring 30, and the inner diameter D5 of the movable ring 6 is provided. It is set smaller than the outer diameter D4 of this screw conveyor 16. There.

By this structure, all the conventional faults can be eliminated.

According to the present invention, since the belt press dehydrator, which is smaller and simpler than the conventional one, can be used, the number of filter belts and rollers, which are essential components of the expensive belt press dehydrator, can be reduced, thereby reducing the installation cost and operating cost. And maintenance costs can be reduced. Thus, the cost of the entire sludge dewatering device can be reduced.

In addition, as a device for pretreating the sludge supplied to the sludge dewatering apparatus, the size of the equipment is very large and expensive, the concentration tank, the storage tank and the centrifugal concentrator are unnecessary, and the time required for the pretreatment of the sludge can be shortened. For this reason, the generation of odor due to the sludge decay can be effectively suppressed. In addition, since the centrifugal concentrator becomes unnecessary, the amount of flocculant used can be minimized, and the cost required for sludge treatment can be achieved. In addition, when the filtrate generated from the belt press dehydrator is treated again, a defect in which the sludge settling efficiency decreases can be prevented.

Moreover, the structure of a belt press dehydrator can be especially simplified, and the sludge cake with a low water content can be obtained by such a dehydrator.

In addition, it is possible here to minimize the overall apparatus by drastically reducing the volume of the sludge by using a solid-liquid separation device capable of dewatering the amount of sludge in a water content of about 90% by weight in a shorter time than the belt press dehydrator. That is, when the water content of the sludge discharged from the concentration tank of the conventional apparatus shown in Figure 6 is at least 97.5% and the water content of the sludge discharged from the solid-liquid separation device as 90 to 94% as described herein, the ratio of the volume ( 100-97.5) / (97.5-94) = 1 / 1.4 to (100-97.5) / (97.5-90) = 1/3. That is, the sludge throughput by the conventional apparatus is 1.4 to 3.0 times the sludge throughput of the apparatus of the present application. Therefore, the device of the present invention can reduce the dewatering device than the conventional device. Thus, if necessary, it is also possible to use two or more belt press dehydrators of the simple structure used herein to reduce the dehydration treatment time.

Claims (4)

delete Pressing the flocculant into the sludge to form flocs, a solid-liquid separation device for condensing the sludge flocculated by the flocculating device, and a sludge concentrated by the solid-liquid separation device between the water-permeable filter belts. And a belt press dehydrator for dewatering the sludge to simultaneously concentrate and dewater the sludge, wherein the belt press dehydrator is wound around a pair of rollers to form an endless first filtration belt and a first filtration belt. A second filter belt having an endless shape which is disposed to face each other and is wound around the pair of rollers and pressurizes the sludge between the first filter belt and the sludge after the pressurization is separated from the second filter belt. Sludge dewatering apparatus provided with the scraper. A flocculation device in which the reaction tank, the settling basin through which the reaction tank is connected, a flocculant is added to the sludge introduced from the settling basin to form flocs, and a solid-liquid separation device that concentrates the sludge flocculated by the flocculation device; And a belt press dehydrator for dewatering the sludge concentrated by the solid-liquid separation device between water permeable filter belts. The method of claim 3, A sludge dewatering system having means for bypassing sludge from the reaction tank directly to the flocking device.