JP2009006319A - Sludge dehydrator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sludge dehydrator which can be easily miniaturized and have excellent coagulation efficiency. <P>SOLUTION: In the sludge dehydrator A, the sludge in a coagulation tank 5 is stirred with a coagulant charged into it to produce coagulated sludge, which is dehydrated through compression in a vertical screw press 7. A conduit 11 including a line mixer 2 therein is provided for force feeding the sludge to the coagulation tank 5 by a pump. An input port 12 for charging an anionic coagulant is fitted to the line mixer 2 or to the conduit 11 at the upstream side of the line mixer 2. Another input port 51 for charging the anionic coagulant is also fitted to the coagulation tank 5. The required amount of the anionic coagulant is segmented and fractionally charged into the input port 12 and 51. A cationic coagulant is also charged into an input port 52 fitted to the coagulation tank 5 at the downstream side of the input port 51. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dewatering apparatus for sludge generated mainly during dredging work for dam lakes, harbors and rivers, tunnel excavation work, and the like.

  The mixture of water, clay, silt, etc. (hereinafter referred to as “sludge”) generated during dredging work in dam lakes, harbors and rivers, tunnel excavation work, etc., is separated into drainage by a dehydration device to form dehydrated cake. The flocculant is added to the sludge in the agglomeration reaction tank and stirred to produce agglomerated sludge (floc). This agglomerated sludge is supplied into the filter cylinder of the screw press, and the screw disposed in the filter cylinder rotates. Squeezed and dehydrated while being conveyed through the filter tube to form a dehydrated cake.

  In an agglomeration reaction tank, it is known that an anionic flocculant is first added to sludge and reacted, and then a cationic flocculant is added and reacted to improve the agglomeration effect ( For example, see Patent Document 1).

  However, two agglomeration reaction tanks are provided, and an anionic flocculant is added to the sludge in the upstream agglomeration reaction tank and stirred, and a cationic flocculant is introduced and stirred in the downstream agglomeration reaction tank. When this is assumed, it is necessary to pump the agglomerated sludge generated in the upstream agglomeration reaction tank to the downstream agglomeration reaction tank using a pump. Moreover, since two agglomeration reaction tanks are provided, the sludge dewatering apparatus is increased in size. And this is because it is often difficult to secure a large installation space in mountainous areas where dredging work is performed on dam lakes and urban areas where tunnel excavation work is done. This is contrary to the desire that it is preferable.

Therefore, it is assumed that in one agglomeration reaction tank, an anionic flocculating agent is introduced into the sludge at its upstream portion and a cationic flocculating agent is introduced at its downstream portion.
Japanese Patent Publication No. 3723625

  However, in one agglomeration reaction tank, when an anionic flocculant is introduced into the sludge at the upstream part thereof and a cationic flocculant is introduced at the downstream part thereof, in order to sufficiently exert the agglomeration effect, It is necessary to add the cationic flocculant after the sludge and the anionic flocculant are mixed and sufficiently reacted. To this end, when the processing speed is taken into account, there is a problem that the agglomeration reaction tank becomes longer in the upstream / downstream direction and the sludge dewatering apparatus becomes larger.

  In view of the above circumstances, an object of the present invention is to provide a sludge dewatering apparatus that has a high agglomeration effect and can be downsized.

  The present invention provides a sludge dewatering apparatus in which a flocculant is added to a sludge in a flocculation reaction tank and stirred to produce the flocculated sludge, and the flocculated sludge is pressed and dehydrated with a screw press. A line mixer for pumping sludge toward the pipe, and a line mixer is interposed in the pipe line, and the line mixer or a part of the pipe line upstream from the line mixer is a first for an anionic flocculant. An input port is provided, and a second input port for an anionic flocculant is provided in the agglomeration reaction tank, and a necessary amount of an anionic flocculant is supplied from the first input port and the second input port. In addition to being charged in a dispersed manner, a cationic flocculant is charged into the agglomeration reaction tank from an inlet provided on the downstream side of the second inlet.

  According to the present invention, a line mixer is provided upstream from the agglomeration reaction tank, and the anionic flocculant is charged from the first inlet provided in the line mixer or a part of the pipe upstream of the line mixer. Is done. Therefore, the sludge is agitated by the line mixer, sufficiently reacted with the anionic flocculant, and transferred to the agglomeration reaction tank in a state of being agglomerated to some extent in advance. The length of the upstream / downstream direction can be shortened in the portion where the flocculant is added and stirred, compared to the portion where the anionic flocculant is charged and stirred only in the assumed agglomeration reaction tank. . Therefore, the coagulation effect is high and the sludge dewatering apparatus can be downsized.

  Further, since the anionic flocculant is also charged from the second charging port of the agglomeration reaction tank, it is necessary to increase the aggregating effect as compared with the case where the anionic flocculant is charged only by the line mixer. An amount of anionic flocculant can be charged. Here, when a large amount of anionic flocculant is added to the sludge with a line mixer, the viscosity of the agglomerated sludge becomes high, and it becomes impossible to pump the pipeline toward the agglomeration reaction tank downstream of the sludge. Or a high-power pump is required. Therefore, in the line mixer, an anionic flocculant having a viscosity that can be pumped with a low-power pump is introduced from the first inlet, and from the second inlet provided in the aggregation reaction tank. Furthermore, by adding an anionic flocculant, it becomes possible to add an amount of an anionic flocculant necessary to increase the coagulation effect as a total to the sludge.

  Further, in the present invention, the screw press includes a filter cylinder having a longitudinal direction as a longitudinal axis, and a screw rotatably disposed in the filter cylinder, and the screw press is provided through a receiving port provided at a lower portion of the filter cylinder. Aggregated sludge is supplied into the filter cylinder, and the aggregated sludge is squeezed and dehydrated while being conveyed upward in the filter cylinder by the rotation of the screw. A reaction vessel is preferably provided.

  In this case, since the agglomeration reaction tank is disposed above the receiving port provided at the lower part of the filter cylinder of the vertical screw press, a cradle on which the agglomeration reaction tank is placed can be provided by downsizing the agglomeration reaction tank. It is possible to reduce the size, and it is possible to effectively reduce the size of the entire sludge dewatering apparatus.

  A sludge dewatering apparatus according to an embodiment of the present invention will be described. With reference to FIG. 1, this sludge dewatering apparatus A mainly includes a sludge storage tank (raw mud tank) 1, a line mixer 2, an anionic flocculant supply unit 3, a cationic flocculant supply unit 4, and an agglutination reaction. The tank 5 is composed of a supply pipe 6, a vertical screw press 7, and a filtrate treatment tank 8.

  The sludge storage tank 1 stores sludge whose concentration has been adjusted. Sludge is a mixture of water, clay, silt, etc., from which gravels and sand have been removed from sludge generated during dredging work in dam lakes, harbors and rivers, tunnel excavation work, etc. The sludge is appropriately diluted with water so that its moisture content is about 80% and the concentration is adjusted. Moreover, it is preferable to mix the fly ash of about 10% of sludge solid content in the sludge from the viewpoint of solidification and enhancing the coagulation effect described later. The sludge stored in the sludge storage tank 1 is stirred by a stirring blade that is rotationally driven by a motor M in order to prevent sedimentation. The sludge stored in the sludge storage tank 1 is discharged by the pump P <b> 1 and is pumped toward the agglomeration reaction tank 5 through the pipeline 11.

  The line mixer 2 is interposed in a pipeline 11 that connects between the sludge storage tank 1 and the agglomeration reaction tank 5. The line mixer 2 is a static mixer in which a spiral baffle plate is provided in a pipe, and stirs the sludge discharged from the sludge storage tank 1 by the pump P1 and pumped through the pipeline 11.

  The anionic flocculant supply unit 3 mainly includes an anionic flocculant dissolution tank 31 and two communicating anionic flocculant storage tanks 32. The anionic flocculant dissolution tank 31 mixes and stirs the anionic flocculant supplied from a feeder (not shown) and the fresh water supplied from the fresh water tank 33 with a stirring blade that is rotationally driven by a motor M, Dissolve anionic flocculants. The dissolved anionic flocculant (hereinafter referred to as an anionic flocculant) is discharged by the pump P2 and supplied to the anionic flocculant reservoir 32. The anionic flocculant storage tank 32 stores the anionic dissolution flocculant in the tank while being stirred by a stirring blade that is rotationally driven by the motor M.

  The anionic flocculating agent stored in one anionic flocculating agent storage tank 32 is discharged by the pump P3 and is provided at the inlet (first inlet) provided in the portion of the pipe line 11 upstream from the line mixer 2. ) Is introduced into the pipe line 11 from 12 and is agitated and mixed with sludge by the line mixer 2. When an anionic flocculant is mixed with sludge, the viscosity increases. For this reason, if the anionic dissolution flocculant is excessively charged from the inlet 12, the sludge cannot be pumped to the aggregation reaction tank 5. Therefore, the amount of the anionic dissolution flocculant charged from the charging port 12 is set to such an amount that the sludge can be pumped to the aggregation reaction tank 5. The anionic dissolution flocculant stored in the other anionic flocculant storage tank 32 is discharged by the pump P4 and enters the aggregation reaction tank 5 from the input port (second input port) 51 provided in the aggregation reaction tank 5. It is thrown into. The input amount of the anionic dissolution flocculant from the input port 51 was obtained by subtracting the input amount of the anionic dissolution flocculant from the input port 12 from the amount of the anionic dissolution flocculant required to increase the sludge aggregation effect. Set to quantity.

  The cationic flocculant supply unit 4 is mainly composed of a cationic flocculant dissolution tank 41 and a cationic flocculant storage tank 42. The cationic flocculant dissolution tank 41 mixes and stirs the cationic flocculant supplied from a feeder (not shown) and the fresh water supplied from the fresh water tank 33 with a stirring blade that is rotationally driven by the motor M, Dissolve the cationic flocculant. The dissolved cationic flocculant (hereinafter referred to as “cationic flocculant”) is discharged by the pump P5 and supplied to the cationic flocculant reservoir 42. The cationic flocculant storage tank 42 stores the cationic dissolved flocculant in the tank while being stirred by a stirring blade that is rotationally driven by the motor M.

  The cationic dissolution flocculant stored in the cationic flocculant storage tank 42 is discharged by the pump P6 and charged into the agglomeration reaction tank 5 from the charging port 52 provided downstream from the charging port 51 of the aggregation reaction tank 5. Is done. From the inlet 52, an amount of a cationic dissolution flocculant necessary for increasing the sludge aggregation effect is charged.

  The agglomeration reaction tank 5 is not shown in detail, but the rotating shaft on which the stirring blades are formed is driven to rotate by the motor M to stir the staying matter staying inside, and the staying matter is moved from the upstream side to the downstream side. It is a two-shaft paddle mixer that is transported to. In addition, a rotating shaft having a feed blade formed in the agglomeration reaction tank 5 may be provided, and the staying material may be transferred by rotating the shaft by a motor M. The agglomeration reaction tank 5 is disposed at the same height as the upper part of the vertical screw press 7 by the gantry 53.

  Sludge that has been agitated and mixed with the anionic flocculant in the line mixer 2 and has agglomerated to some extent to increase the viscosity is supplied into the agglomeration reaction tank 5 from the receiving port 54. The sludge supplied into the agglomeration reaction tank 5 is agitated by the stirring blade as a stagnant substance and is transferred to the downstream side by the feed blade, and the anionic dissolution flocculant charged from the inlet 51 and the downstream side thereof. By sequentially mixing and reacting with the cationic dissolving flocculant charged from the charging port 52, the agglomeration further proceeds to become agglomerated sludge (floc).

  The side wall on the downstream side of the tank where the stirring blade and the feed blade rotate as necessary is a weir 55, and the aggregated sludge overflowing the weir 55 is provided at the discharge port 56 provided at the bottom of the aggregation reaction tank 5. Falls downward from An inclined screen 57 is disposed immediately below the discharge port 56. The inclined screen 57 is a screen for draining in which a lot of fine meshes are formed, and is inclined on a receiving box. The liquid and fine particles that have passed through the mesh of the inclined screen 57 are sent to the filtrate treatment tank 8 through a receiving box. On the other hand, the coagulated sludge that cannot pass through the mesh of the inclined screen 57 falls into the supply pipe 6.

  The supply pipe 6 is a pipe for supplying the coagulated sludge from the coagulation reaction tank 5 to the vertical screw press 7 and extends mainly in the vertical direction. The coagulation sludge discharged from the discharge port 56 of the coagulation reaction tank 5 is the upper part thereof. Accept from the inside. The supply pipe 6 or the agglomeration reaction tank 5 is provided with an opening (not shown) communicating with the outside at the upper portion thereof, and air freely passes through this opening, and the pressure in the supply pipe 6 is changed to the atmospheric pressure. It is supposed to be equal.

  The supply pipe 6 has a thin sub pipe 62 that branches from the main pipe 61 and extends in the vertical direction separately from the thick main pipe 61 that connects the agglomeration reaction tank 5 and the vertical screw press 7. Yes. The sub-pipe 62 is provided with two high and low interface sensors 63 and 64. The interface sensors 63 and 64 detect whether or not the height of the interface between the coagulated sludge and water exceeds a predetermined height. By providing the two high and low interface sensors 63 and 64 in this way, it is possible to maintain a state where the height of the coagulated sludge staying in the supply pipe 6 is within a predetermined range. Specifically, when it is detected by the interface sensor 63 at a higher position that the height of the coagulated sludge staying in the supply pipe 6 exceeds the upper limit, the pump P1 is stopped and the sludge storage tank 1 Stop supplying sludge. On the other hand, when it is detected by the interface sensor 64 at a low position that the height of the coagulated sludge staying in the supply pipe 6 is lower than the lower limit, the output of the pump P1 is increased, and the sludge from the sludge storage tank 1 is increased. Increase supply.

  The vertical screw press 7 includes a filter cylinder 71 whose longitudinal direction is the longitudinal direction, a screw 72 rotatably disposed in the filter cylinder 71, and a gap S in the horizontal direction so as to cover the periphery of the filter cylinder 71. The aggregated sludge supplied to the filter cylinder 71 is compressed and dehydrated while being conveyed upward by the screw 72, and the separated water is discharged from the filter cylinder 71 into the gap S.

  The vertical screw press 7 has a quadrangular columnar frame 74 composed of columns, beams, and the like and having a vertical direction as a longitudinal direction, and a bottom plate 75 is horizontally provided below the frame 74. On the bottom plate 75, a cylindrical filter tube 71 formed of punching metal or the like is erected. The cover cylinder 73 is composed of a shield plate attached so that the lower end abuts against the bottom plate 75 between the vertical columns constituting the frame body 74. A receiving port 76 is provided at the lower portion of the filter cylinder 71, and the coagulated sludge supplied from the supply pipe 6 is introduced into the filter cylinder 71 from the receiving port 76. A reinforcing frame is provided on the outer peripheral surface of the filter cylinder 71.

  A screw 72 is rotatably inserted into the filter cylinder 71. The screw 72 includes a tapered screw shaft that gradually increases in diameter from the lower end side to the upper end side of the filter tube 71 and a helical screw blade fixed to the outer peripheral surface of the screw shaft. The screw 72 is rotationally driven by a motor M provided above the filter cylinder 71.

  When the screw 72 is rotated, the coagulated sludge received from the receiving port 76 is conveyed upward from below the filter cylinder 71 by the feeding action by the screw blades. Since the space between the filter cylinder 71 and the screw shaft is gradually narrowed upward, the coagulated sludge is squeezed while being conveyed upward of the filter cylinder 71. The moisture of the coagulated sludge is squeezed out through the filter cylinder 71, falls in the gap S as a filtrate, and is discharged to the filtrate treatment tank 8 through an opening (not shown) formed in the bottom plate 75 and a water collecting tank 77. Is done. Further, a water spray pipe 78 for spraying water to clean the outer surface of the filter cylinder 71 is provided, and this water is similarly discharged to the filtrate treatment tank 8. A discharge port 79 a is opened on the bottom surface of the discharge chamber 79 connected to the upper end of the filter cylinder 71. The dewatered cake C, which is the dewatered agglomerated sludge, is pushed out from the discharge port 79a to the discharge chamber 79 and discharged to the outside through the discharge port chute 79b. Further, a baffle plate 79d is provided above the discharge port 79a in a state of being biased toward the discharge port 79a via an air cylinder 79c, and the dehydrated cake C is pushed up while the baffle plate 79d is pushed up. More discharged.

  The filtrate treatment tank 8 treats the wastewater comprising the filtrate discharged from the vertical screw press 7 and the liquid that has passed through the mesh of the inclined screen 57. In the drainage, a small amount of fine sludge particles that have passed through the fine holes formed in the filter cylinder 71 and the inclined screen 57 also remain.

  The filtrate treatment tank 8 includes a precipitation tank 81 and a drain tank 82. The sedimentation tank 81 receives drainage. The fine particles of sludge contained in the waste water are precipitated with the passage of time and are deposited at the bottom of the settling tank 81. A flocculant may be added to agglomerate the sludge fine particles to promote precipitation. Sludge fine particles settled on the bottom of the settling tank 81 are discharged by the pump P7 and sent back into the pipe line 11 in the portion between the line mixer 2 and the agglomeration reaction tank 5. In addition, you may send back in the pipe line 11 of the part between the sludge storage tank 1 and the line mixer 2, or to the sludge storage tank 1. FIG.

  A weir 83 is provided between the settling tank 81 and the drainage tank 82, and the supernatant of water stored in the settling tank 81 passes through the weir 83 and is discharged to the drainage tank 82. The wastewater stored in the drainage tank 82 is discharged by the pump P8 and sent to the miscellaneous drainage tank 9.

  The drain tank 82 is provided with a float switch (not shown). This float switch is a level sensor that detects whether or not the water level of the drainage tank 82 is within a predetermined range. When the water level exceeds the upper limit of the predetermined range, the pump P1 is stopped and the sludge storage tank Stop the supply of sludge from 1. On the other hand, when the water level falls below the lower limit of the predetermined range, the pump P8 is stopped and the transfer of the drainage from the drainage tank 82 to the miscellaneous drainage tank 9 is stopped.

  By the way, in the vertical screw press 7, in order to assist the agglomerated sludge to move upward in the filter cylinder 71, it is necessary to pressurize and supply the agglomerated sludge to the filter cylinder 71. Here, when the flocculation reaction tank 5 is installed on the ground, it is necessary to pump the flocculated sludge from the flocculation reaction tank 5 to the filter tube 71. And agglomerated sludge is grind | pulverized with a pump, and a fine particle part arises. Since the fine sludge content passes through the filter cylinder 71 and is discharged to the filtrate treatment tank 8, it is necessary to send it back and perform the treatment again, resulting in poor dewatered cake production efficiency.

  On the other hand, in the sludge dewatering apparatus A according to the present embodiment, the agglomeration reaction tank 5 is positioned at the same height as the upper part of the vertical screw press 7, so that the discharge port at the bottom of the agglomeration reaction tank 5 is provided. The supply pipe 6 that communicates 56 and the receiving port 76 provided at the lower portion of the filter cylinder 71 is long in the vertical direction. By maintaining the state in which the aggregated sludge stays in the supply pipe 6, the aggregated sludge is pressurized and supplied into the filter cylinder 71 of the vertical screw press 7 by its own weight. Therefore, unlike the case of pumping, almost no sludge is produced, and the production efficiency of the dewatered cake C is improved.

  Here, the vertical screw press 7 is suitable because it is often difficult to secure a wide installation space in mountainous areas that are the site of dredging work on dam lakes and urban areas that are sites of tunnel excavation work, etc. Used. The agglomeration reaction tank 5 is positioned at the same height as the upper part of the vertical screw press 7 by the gantry 53. However, when the agglomeration reaction tank 5 is enlarged, the gantry 53 is also enlarged and installed in a narrow space. Becomes difficult. For this reason, the agglomeration reaction tank 5 is desired to be small.

  However, in order to fully exhibit the coagulation effect, an anionic coagulant is introduced in the upstream portion of the coagulation reaction tank 5, and after the sludge and the anionic coagulant are mixed and sufficiently reacted, the coagulation reaction tank 5 It is necessary to add a cationic flocculant at the downstream side of the basin. Therefore, when processing speed is considered, there exists a fault that the agglomeration reaction tank 5 becomes long in an upstream / downstream direction.

  On the other hand, in the sludge dewatering apparatus A according to the present embodiment, an anionic dissolving flocculant is introduced from an inlet 12 provided in a portion of the pipe line 11 upstream from the line mixer 2, and the sludge is removed by the line mixer 2. And an anionic dissolution flocculant are stirred and mixed. An amount of anion obtained by subtracting the amount of anionic dissolution flocculant from the input port 12 from the amount of anionic dissolution flocculant necessary to increase the sludge aggregation effect from the input 51 of the aggregation reaction tank 5. System dissolving flocculant is added. Therefore, the length in the upstream and downstream direction of the portion where the anionic dissolution flocculant and sludge in the upstream portion from the inlet 53 for the cationic flocculant of the agglomeration reaction tank 5 are mixed and reacted is shortened. 5 is downsized. Thereby, the mount 53 can also be reduced in size and can be easily installed in a narrow space.

  In the above-described sludge dewatering apparatus A, the case where the anionic dissolving flocculant is introduced into the pipe 11 from the inlet 12 provided in the pipe 11 upstream of the line mixer 2 has been described. However, an anionic dissolving flocculant may be introduced into the line mixer 2 from an inlet provided in the line mixer 2.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the sludge dehydration processing apparatus which concerns on one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sludge storage tank, 2 ... Line mixer, 3 ... Anionic flocculant supply part, 4 ... Cationic flocculant supply part, 5 ... Coagulation reaction tank, 6 ... Supply pipe, 7 ... Vertical screw press, 8 ... Filtrate Treatment tank, 9 ... miscellaneous wastewater treatment tank, 12 ... inlet (first inlet for anionic flocculant), 51 ... inlet (second inlet for anionic flocculant), 52 ... inlet (Inlet for the cationic flocculant), 53 ... Stand, 54 ... Reception port, A ... Sludge dewatering apparatus

Claims (2)

In the sludge dewatering device, the flocculant is added to the sludge in the agglomeration reaction tank and stirred to produce agglomerated sludge, and the agglomerated sludge is pressed and dehydrated with a screw press.
A line for pumping sludge toward the agglomeration reaction tank is provided, a line mixer is interposed in the line, and the line mixer or an anionic flocculant is provided on the upstream side of the line mixer. And a second input port for an anionic flocculant is provided in the agglomeration reaction tank, and a necessary amount of anion is obtained from the first input port and the second input port. The sludge is characterized in that the system flocculant is dispersed and charged, and the canyon-based flocculant is charged into the agglomeration reaction tank from the input port located downstream from the second input port. Dehydration processing equipment. The screw press includes a filter cylinder having a longitudinal direction as a longitudinal axis, and a screw rotatably disposed in the filter cylinder, and agglomerated sludge enters the filter cylinder from a receiving port provided at a lower portion of the filter cylinder. Is a vertical screw press in which the condensed sludge is compressed and dehydrated while being conveyed upward in the filter cylinder by the rotation of the screw,
The sludge dewatering apparatus according to claim 1, wherein the agglomeration reaction tank is disposed above the receiving port.