KR20150053993A - Sludge dehydration processing method and dehydration processing device - Google Patents

Abstract

A dewatering method and dewatering apparatus capable of sufficiently dewatering in a screw press machine. The dewatering method of sludge dewatering the concentrated sludge in a sludge thickener (11) in a screw press (31) comprises a screw press , The screw blade 33b is not provided on the outer periphery of the rotating shaft constituting the screw shaft over a predetermined length in the axial direction of the intermediate portion 46 of the screw shaft 33a, Is directly heated by heated steam or hot air at the sludge inlet side of the sludge tank 35 and dehydrated in the state where the sludge is heated in the screw press.

Description

TECHNICAL FIELD [0001] The present invention relates to a sludge dewatering method and a dewatering apparatus,

The present invention relates to a technique for heating and dehydrating sludge.

When the waste water is dehydrated, the flocculation tank, the sludge thickener and the screw press are sequentially connected. The wastewater from the wastewater is supplied to the flocculation tank, and the flocculant is added. This wastewater is coagulated and becomes sludge. The sludge is supplied to the sludge thickener and is dehydrated by gravity. The sludge is reduced in water content and concentrated. The concentrated sludge is supplied to a screw press, gravity dehydrated, and further compressed and dehydrated. The concentrated sludge dehydrated in this screw press machine is further reduced in water content and becomes a dehydrated cake.

When the sludge is dewatered by a screw press machine, as disclosed in Patent Document 1, the screw press machine supplies steam or hot air to the hollow portion of the screw shaft. Or operate the electric heater built into the screw shaft. The screw shaft heats the outer peripheral wall. The screw shaft in the outer tube of filtration is rotated. The sludge is dehydrated while being heated at the outer peripheral wall of the screw shaft while being conveyed while being compressed in the spiral conveyance passage between the outer cylinder and the screw shaft. This sludge is heated and the temperature is raised, the viscosity of the contained liquid is lowered, and the liquid is easily separated from the solid. It is dehydrated in a state in which it is easily dehydrated. The dehydration efficiency is enhanced.

However, in the case of dewatering the sludge by heating the sludge with a screw press machine, the sludge is indirectly heated via the outer peripheral wall of the screw shaft while the spiral conveyance passage between the outer cylinder and the screw shaft is moved. The outer peripheral wall of the screw shaft is made of a stainless steel plate. The indirect heating through the stainless steel sheet has a problem that the heating efficiency is low as compared with the direct heating without the interposed steel sheet.

For direct heating of the sludge, there is a method of blowing steam into the sludge of the flocculation reaction tank. In this method, the sludge heated in the flocculation reaction tank is supplied to the screw press in a state in which the water content is lowered when the sludge is concentrated in the concentrator. The liquid separated from the sludge in the concentrator is not supplied to the screw press. The heat contained in the separated liquid is not used for dewatering in the screw press machine. All the heat added to the sludge in the flocculation reaction tank is not effectively used. There is a lot of heat loss. There is a problem that the heating efficiency is not high.

To solve these problems, the inventors of the present invention have found that, in the dehydration treatment for concentrating sludge in a sludge thickener and dewatering in a screw press, the sludge concentrated in the sludge concentrator is directly heated by blowing steam or hot air, The sludge is dehydrated in a state where the temperature of the sludge is elevated (Patent Document 2).

The method of Patent Document 2 is based on the following conception.

In the dewatering process in which the sludge is concentrated in the sludge concentrator and dehydrated in the screw press, direct heating of the sludge, as illustrated in Fig. 1, is performed after the sludge is concentrated in the sludge concentrator, . Particularly, it is performed immediately before dehydration in a screw press machine.

After the liquid is separated from the sludge concentrator, the volume of the sludge is reduced by the separated liquid, and the amount of heat consumed by heating is reduced. Further, all of the heated sludge is dehydrated in the screw press, and there is no heat loss. Heating efficiency is high. High dehydration efficiency.

Further, the sludge concentrated in the sludge concentrator was flocculated by adding a flocculant when directly heated. The flocculation reaction is preferably carried out in a state where the temperature is raised. The dehydration efficiency becomes higher.

Specific examples based on the implantation include, for example, the following specific examples.

First embodiment

In a first example using the above principle, a direct heating chamber for directly heating the sludge is provided between the sludge thickener and the screw press. In the direct heating chamber, a direct heating device for blowing steam or hot air to the sludge is provided. Further, a device for stirring the sludge is provided.

The sludge concentrated in the concentrator is supplied directly to the heating chamber. In the direct heating chamber, steam or hot air is blown into the sludge, and the sludge is stirred. The temperature of the sludge in the direct heating chamber is increased by heating, and the viscosity of the contained liquid is lowered. The liquid tends to separate from the solid. This sludge is supplied to a screw press and is dehydrated in a screw press.

Further, in the direct heating chamber, an apparatus for adding an aggregating agent to the sludge is provided. The flocculation reaction of the sludge is preferably performed in a state where the temperature is raised. The dehydration efficiency in the screw press becomes higher.

Second Embodiment

In the second example, the direct heating chamber in the first example is assembled to the inlet portion of the screw press. In the screw press machine, a feed passage is connected to a spiral-shaped feed passage between the outer cylinder and the screw shaft. The inlet passage and the inlet side portion of the transfer passage are directly made into the heating chamber. In the injection path, a direct heating device for blowing steam or hot air to the sludge is provided. A stirring piece (stirring piece) is provided on the inlet side portion of the screw shaft. An agitating device for agitating the sludge with agitating pieces rotating together with the screw shaft constitutes a part of the transfer path side of the transfer passage.

The sludge concentrated in the sludge concentrator is supplied to the feed passage of the screw press. This sludge passes sequentially through the inlet passage and the inlet port side portion of the transfer passage. At that time, water vapor or hot air is blown and stirred with a stirring piece. The temperature is directly heated and the liquid becomes easy to separate from the solid. This sludge is conveyed while being compressed in the conveyance passage, and is dehydrated.

In the second example, the apparatus becomes compact. The sludge is subjected to direct heating immediately before dewatering. The time and distance between the direct heating of the sludge and the dehydration are shortened. Heat loss is reduced.

In addition, the feeding passage is provided with a device for adding the flocculant to the sludge. The flocculation reaction of the sludge is preferably performed in a state where the temperature is raised.

(Patent Document 1) Japanese Laid-Open Patent Application No. 50-157967 (Patent Document 2) Japanese Patent Application No. 2011-050665

The present invention further develops a sludge dewatering method and a sludge dewatering apparatus wherein the sludge is concentrated in a sludge concentrator and the sludge is directly heated before dewatering in a screw press. The state of the sludge in the feed passage of the screw press machine was examined in detail, and the sludge was unevenly distributed in the feed passage. If the sludge is unevenly distributed, heat loss may occur or dewatering in the screw press may not be sufficient.

An object of the present invention is to provide a dewatering treatment method and dewatering apparatus capable of sufficiently dewatering in a screw press machine.

The sludge dewatering method of the present invention is a method of dewatering sludge concentrated in a sludge concentrator in a screw press.

The screw press machine is a screw press machine in which a screw wing is not provided on the outer periphery of a rotary shaft constituting a screw shaft over a predetermined length in the axial direction of an intermediate portion of the screw shaft.

The concentrated sludge is directly heated by heated steam or hot air on the sludge inlet side of the conveyance passage constituting the screw press, and the sludge is dehydrated in the screw press.

Further, the concentrated sludge is characterized by adding sludge flocculant to coagulate when heated directly.

The dehydration apparatus of the present invention is used in a dehydration treatment method of the sludge, and comprises a sludge thickener for concentrating the sludge and a screw press for dehydrating the concentrated sludge.

The sludge thickener is a gravity concentrator that is concentrated by flowing sludge down the slope. The screw press machine is characterized in that the screw vane is not provided on the outer periphery of the screw shaft over a predetermined length in the axial direction of the middle portion of the screw shaft but is integrated with the transfer passage on the side of the sludge inlet port of the transfer passage constituting the screw press machine An input passage for directly heating the concentrated sludge is provided, and means for blowing heated steam or hot air to the input passage is provided.

In addition, the charging passage of the dehydration apparatus further comprises means for adding a coagulant to the concentrated sludge.

Another dehydration treatment apparatus of the present invention comprises a sludge thickener for concentrating sludge and a screw press for dehydrating concentrated sludge,

Wherein the sludge thickener is a gravity concentrator for concentrating the sludge by flowing down the sludge,

The screw press machine is characterized in that the screw vanes are not provided on the outer periphery of the rotary shaft constituting the screw shaft over a predetermined length in the axial direction of the middle portion of the screw shaft, Wherein the direct heating chamber has stirring means for stirring the concentrated sludge and means for blowing heated steam or hot air.

The stirring means is an agitating device for stirring the sludge with a stirring piece rotating together with the screw shaft.

Since a screw press without a screw blade is used over a predetermined length in the axial direction of the middle part of the screw shaft, the dewatering of the sludge is high in dewatering efficiency and high in heating efficiency.

Fig. 1 is a process diagram of sludge dewatering treatment of the present invention.
Fig. 2 is a schematic front view of the sludge dewatering apparatus in the first example of the embodiment; Fig.
3 is a schematic enlarged view of the concentrator of the sludge dewatering device viewed from the inlet side thereof.
4 is a schematic cross-sectional view taken along line AA of Fig.
5 is a view showing the charging state of the sludge in the transfer passage.
6 is a schematic front view of a sludge dewatering apparatus in a second example of the embodiment.

First Embodiment (refer to Figs. 1 to 5)

In this example, as shown in Figs. 1 and 2, the sludge agglomerated in the agglomeration tank 1 is concentrated in the sludge thickener 11, and is directly heated in the screw press 31 to be dehydrated.

As shown in Fig. 2, the sludge dewatering apparatus of the present invention comprises a sludge thickener 11 and a screw press 31 connected in series. Further, the flocculation tank (1) can be connected to the sludge thickener (11).

The flocculation tank 1 has a sludge tank 2 connected to the flooded water supply passage 3 and the flocculant supply passage 4 and provided with a stirring device 5. In the sludge tank (2), a coagulant is added to the wastewater from the wastewater and mixed by stirring. The wastewater undergoes agglomeration reaction to produce a flock, which becomes sludge.

The sludge thickener 11 is a gravity concentrator as shown in Figs. 2 and 3. The sludge flows down and is concentrated. The sludge flowing (downflow) passage 12 is provided with a downwardly inclined slope, and the rear upper end serves as an inlet 12a and the front lower end serves as an outlet 12b. The outlet of the sludge tank 2 of the flocculation reaction tank 1 is connected to the inlet 12a of the sludge lowering passage 12.

The sludge lower passageway (12) has a transverse section in the form of a groove, and the bottom of the groove is a plate having a filtration hole. Below the sludge lower passageway 12, a liquid chamber 13 for collecting and discharging the liquid flowing down from the filtration hole of the bottom plate is provided.

As shown in Fig. 2, a device for cleaning the bottom plate having the filtration hole with a brush and controlling the rate at which the sludge flows down is provided on the sludge lower passageway 12, as shown in Fig. This apparatus is provided with a drive shaft 14 and a driven shaft 15 along the transverse direction in the lateral direction on the inlet side and the outlet side on the sludge lower flow path 12. The drive shaft 14 is connected to the electric motor 16 via a transmission mechanism. The drive shaft 14 and the driven shaft 15 respectively fix the chain pulley 17 to the right and left positions. An endless chain 18 is attached to the chain pulley 17 on the left side of the drive shaft 14 and the driven shaft 15. The endless chain 18 is also hooked to the chain pulley 17 on the right side of the drive shaft 14 and the driven shaft 15. On the left and right chains 18 on both sides, the separating plate 19 is mounted across the left and right direction. The separator plate (19) projects the brush (20) on the tip side. On the outer circumferential side of the chain 18 on both sides, the separating plate 19 with the brush 20 is projected outward in parallel at regular intervals. The separating plate 19 with the brush 20 is fitted to the sludge lowering passage 12 in the groove-like cross section shape along the passage cross direction while being positioned on the lower side of the chain 18 on both sides, Is brought into contact with the bottom plate of the sludge lowering passage (12).

When the electric motor 16 is driven, the separating plate 19 with the brush 20 reaches the lower side of the chain 18 around the drive shaft 14, enters the inlet 12a of the sludge lowering passage 12 , And is fitted in the sludge lower passageway (12).

The separating plate 19 is brought into contact with the sludge lowering passage 12 and the sludge lowering passage 12 is lowered to a set speed while the brush 20 is cleaning the bottom plate with the filtering holes. When the separating plate 19 with the brush 20 reaches the outlet 12b of the sludge lowering passage 12, the separating plate 19 comes out of the sludge lowering passage 12 and rotates around the slave shaft 15, And reaches the upper side. The sludge flowing down through the sludge lower passageway 12 flows down while adhering to the sidewall plate 19 with the brush 20 lowering the sludge lower passageway 12 at a set speed. The concentrated sludge flows out from the outlet 12b of the sludge lower passageway 12.

2, the screw press machine 31 is provided with a screw shaft 33 concentrically fitted in an outer cylinder 32 arranged horizontally. The screw shaft 33 is wound around the outer periphery of the rotating shaft 33a with a screw blade 33b in a spiral shape.

The screw blade 33b wound in a helical shape is cut at the axial intermediate portion 46 of the screw shaft. In this intermediate portion 46, the screw blade 33b is not provided on the outer periphery of the rotary shaft 33a.

The end of the screw shaft 33 protrudes from the end side of the outer cylinder 32 and is connected to the electric motor 34 via a transmission mechanism. A spiral transfer passage 35 is formed between the outer cylinder 32 and the wing portion of the screw shaft 33. An inlet passage 36 is connected to the sludge inlet side portion of the transfer passage 35 at an upper position thereof.

The inlet passage 36 is connected to the outlet 12b of the sludge lowering passage 12 of the sludge thickener 11 via a rotary valve 37 at the upper end entrance. The input passage 36 is provided with a level sensor 38. And an apparatus for controlling the amount of sludge in the inflow passage (36). This control device opens and closes the rotary valve 37 based on the height of the sludge in the charging passage 36 detected by the level sensor 38 and controls the sludge concentration in the sludge thickener 11 to the charging passage 36 And the height or amount of the sludge in the feed passage 36 is controlled to a predetermined range.

The feed passage 36 is provided with a direct heating device for injecting heated steam into the sludge. As shown in Figs. 2 and 4, the direct heating apparatus has a plurality of blowing tubes 41 disposed along the axial direction of the screw shaft 33 in the input passage 36. The blowing tube 41 is connected to a heated water vapor generating source (not shown) via a flow control valve 42. The sludge in the inlet passage 36 and the inlet port side of the feed passage 35 is directly heated by blowing heated steam from the blowing tube 41. The sludge temperature rises.

The inlet passage 36 is provided with a device for controlling the temperature of the sludge to be directly heated. In this temperature control device, a temperature sensor 43 is provided in the input passage 36. The opening degree of the flow control valve 42 is adjusted based on the sludge temperature detected by the temperature sensor 43 to increase or decrease the flow rate of the heated water vapor blown into the sludge from the blowing tube 41, The temperature is controlled to a preset range.

In addition, the rotary valve 37 prevents the water vapor in the input passage 36 from flowing out upward when the rotary valve 37 is closed.

In addition, a coagulant addition device 45 for adding a coagulant to the sludge is provided in the charging passageway 36. By this flocculant addition device 45, an auxiliary coagulant is added to the concentrated sludge, and the flocculant is reacted in a state where the temperature is raised. Sludge re-agglomerates.

The transfer passage 35 has a sludge inlet port side portion as a temperature rising portion and a sludge drop port side portion as a liquid separation portion. The outer cylinder 32 has a non-filtration property in which the intermediate portion 46 has no filtration hole, and the dropping-port side portion is made filterable with a filtration hole. A water draining section 39 is provided at the lower part of the inlet port side to be water sealed, and this draining section 39 is made filterable with a filtration hole.

The sludge may be agitated by providing an agitating piece rotating together with the screw shaft 33 in the temperature rising zone of the transfer passage 35.

The screw shaft 33 has a helical screw blade 33b wound on the outer periphery of the rotary shaft 33a at an even pitch. The wing portion of the rotary shaft 33a has an outer diameter equalized at the inlet port side portion and is expanded toward the drop port at the drop port side portion.

The transfer passage 35 is a non-compressible passage in which the cross-sectional area is not changed in the temperature rising region of the inlet port side portion and a compressible passage in which the cross-sectional area decreases in the liquid separation region of the dropping port side portion as it approaches the drop port . An intermediate portion 46 is provided between the incompressible passage and the compressible passage, which is a region where the screw vane 33b does not exist.

A liquid chamber 40 for collecting and discharging the liquid flowing down from the filtration hole is provided below the drop port side portion of the filter 32 of the outer tube 32. Below the dropping port of the conveying passage 35, a passage 44 through which the dewatering cake pushed out while being resisted by the resistor is dropped is connected.

A dehydration treatment method for dehydrating concentrated sludge in a concentrator using the dehydration treatment apparatus will be described.

In the case of performing the heating and dewatering method of the sludge by using the dewatering apparatus, the wastewater and the flocculant are supplied to the sludge tank 2 in the flocculation tank (1). The wastewater undergoes flocculation reaction to become sludge. This sludge flows out from the outlet of the sludge tank 2 and flows into the inlet 12a of the sludge lowering passage 12 of the sludge thickener 11.

In the sludge thickener 11, the sludge is concentrated by flowing down the sludge lower passageway 12 at a set speed while being coagulated by the caulking plate 19 with the brush 20 attached thereto. The concentrated sludge flows out from the outlet 12b of the sludge lowering passage 12 and flows into the charging passage 36 of the screw press 31 via the rotary valve 37. [

In the screw press machine 31, the sludge introduced into the charging passage 36 is heated by steam from the blowing tube 41 and flows into the temperature rising zone of the transfer passage 35. Directly heated to raise the temperature. Further, the sludge is added with the auxiliary flocculant from the flocculant addition device 45, stirred by the rotation of the screw shaft 33, and re-flocculated.

Fig. 5 shows the filling state of the sludge in the transfer passage 35. Fig. In FIG. 5, the hatched portion indicates the filling state of the sludge, and the cross-hatched portion indicates the filling state of the sludge in the middle portion 46.

As the temperature rises and the re-agglomerated sludge is sent to the liquid separation zone through the intermediate section 46 in the temperature rising zone and the conveyance passage 35 in the liquid separation zone toward the drop port It is compressed and transported.

Since the intermediate portion 46 is cut by the screw blade 33b, the sludge conveyed to the intermediate portion 46 is compressed over the entire conveyance passage 35, as shown by cross hatching. By providing the intermediate portion, it is possible to (1) maintain the heated state of the sludge that has been re-agglomerated due to the rise in temperature, (2) the heated steam, which is blown into the feed passage 36, It is possible to improve the overall thermal efficiency.

The sludge dewatered in the liquid separation zone of the conveyance passage 35 becomes the dewatering cake, and falls down the passage 44 for falling the cake.

In the embodiment, the sludge has a water content of about 99% by mass when it flows into the sludge thickener 11 from the flocculation tank 1, and the water content when flowing into the screw press 31 from the sludge thickener 11 is 95% Mass%. The water content of the dewatered cake is about 70% by mass. In addition, while flowing from the flocculation tank 1 through the sludge thickener 11 to the screw press 31, the temperature is room temperature. In the screw press 31, while being conveyed while being compressed in the liquid separation zone of the conveyance passage 35, the temperature is about 60 캜.

The second embodiment (see Fig. 6)

6, a direct heating chamber 51 for directly heating sludge is provided between the outlet of the sludge thickener 11 and the inlet passage 36 of the screw press 31 . The direct heating chamber (51) is provided with a direct heating device for injecting heated steam into the sludge and a sludge agitator (49). Further, a coagulant addition device 45 is provided.

In the direct heating apparatus, the blowing tube 41 is connected to the direct heating chamber 51. The blowing tube 41 is connected to the heated water vapor generating source via the flow control valve 42. The sludge in the direct heating chamber (51) is directly heated by blowing heated steam from the blowing tube (41). And a device for controlling the temperature of the sludge. In the temperature control device, a temperature sensor (43) is provided in the direct heating chamber (51). The degree of opening of the flow control valve 42 is adjusted based on the sludge temperature detected by the temperature sensor 43 and the flow rate of the heated water vapor blown into the sludge from the blowing tube 41 is increased or decreased, The temperature is controlled in the set range.

The sludge agitating device 49 is provided with a rotary shaft of the stirring piece portion in the direct heating chamber 51, and the rotary shaft is connected to the electric motor. The sludge in the direct heating chamber 51 is agitated by the rotation of the rotary shaft of the stirring piece portion.

The flocculant addition device (45) adds flocculant to the sludge of the direct heating chamber (51). The auxiliary sludge of the direct heating chamber 51 is added with an auxiliary flocculant, and undergoes flocculation reaction in a state where the temperature is raised.

A rotary valve (50) is provided between the inlet of the direct heating chamber (51) and the outlet of the sludge thickener (11). The rotary valve (50) controls the amount of sludge entering the heating chamber (51) directly from the sludge thickener (11). And prevents the heated water vapor in the direct heating chamber (51) from flowing upward when closed. A rotary valve 52 is provided between the outlet of the direct heating chamber 51 and the feed passage 36 of the screw press 31. The rotary valve 52 controls the amount by which the sludge enters the screw press 31 directly from the heating chamber 51. And prevents the water vapor in the direct heating chamber (51) from flowing out downward when closed. In addition, the rotary valve 52 can be omitted.

The screw press machine 31 is not provided with a direct heating device, a sludge agitator or a flocculant addition device in the feed passage 36 and the feed passage 35. The transfer passage 35 is provided with an intermediate portion 46 which is a region where the screw blade 33b is not present. The outer cylinder 32 is of a filtering type with an overall length of the filtering hole except for the intermediate portion 46. The screw shaft 33 is enlarged as the entire length of the wing portion of the rotary shaft is directed toward the drop hole. The conveying passage 35 is a passage of compressibility whose sectional area decreases as the entire length is directed toward the dropping port.

In the sludge heating / dewatering method of this embodiment, the sludge concentrated in the sludge thickener 11 is directly supplied to the heating chamber 51. In the direct heating chamber 51, heated steam is blown into the sludge, and the sludge is stirred. Also, a flocculant is added to the sludge. The temperature of the sludge in the direct heating chamber 51 is raised and re-agglomerated. The sludge is supplied to the screw press 31 in a state in which the liquid is easily separated from the solid, and is dehydrated in the screw press 31.

The other points are the same as those in the first example. The same parts as those in the first example are given the same reference numerals as those in the first example.

[Modifications]

1. In the above embodiment, the sludge thickener 11 is a gravity concentrator, but other concentrators are used.

2. In the above embodiment, the heat source for directly heating the sludge is heated steam, but other steam or hot air is used.

3. In the first example of the above embodiment, the screw press 31 is provided with a closing device for temporarily closing the passage between the temperature raising zone of the conveying passage 35 and the liquid separating zone. This closing device temporarily closes when the screw press 31 is started in a state in which there is no sludge in the transfer passage 35. Then, the sludge tends to collect in the temperature rising region of the transfer passage 35. Further, the heated water vapor in the temperature rising zone of the transfer passage 35 is prevented from flowing out to the liquid separation zone.

INDUSTRIAL APPLICABILITY The present invention can be used for dehydration treatment of domestic wastewater or industrial wastewater.

1: flocculation tank
2: sludge tank
3: sewage supply passage
4: Coagulant feed passage
5:
11: Sludge thickener
12: sludge channel
13: liquid chamber
14:
15:
16: Electric motor
17: Chain pulley
18: Chain
19: Announcement plate
20: Brushes
31: screw press machine
32: outer tube
33: Screw shaft
34: Electric motor
35:
36: input passage
37: Rotary valve
38: Level sensor
39: Water draining part
40: liquid chamber
41: Blowing tube of steam
42: Flow control valve
43: Temperature sensor
44: passage
45: Coagulant addition device
46: middle part
49: Sludge agitator
50: Rotary valve
51: Direct heating chamber
52: Rotary valve

Claims (6)

A sludge dewatering method for dewatering sludge concentrated in a concentrator using a screw press having a screw shaft wound around the outer periphery of a rotary shaft in a spiral shape,
The screw press machine is a screw press machine in which the screw wing is not provided in the axial middle portion of the screw shaft,
Wherein the concentrated sludge is directly heated by heated steam and / or hot air at a sludge inlet side of a conveyance passage constituting the screw press, and the sludge is dewatered in a heated state in the screw press, / RTI > The dewatering treatment method according to claim 1, wherein when the concentrated sludge is heated directly, sludge flocculant is added and flocculated. A dewatering apparatus used in a dewatering method of sludge according to claim 1,
The dehydration apparatus includes a sludge thickener for concentrating the sludge and a screw press for dehydrating the concentrated sludge,
Wherein the sludge thickener is a gravity concentrator for concentrating the sludge by flowing down the sludge,
The screw press machine is characterized in that the screw vane is not provided on the outer periphery of the rotating shaft constituting the screw shaft over a predetermined length in the axial direction of the middle portion of the screw shaft, and the screw passage is formed on the sludge inlet side of the conveyance passage constituting the screw press machine And a means for directly heating said concentrated sludge so as to be integrated therewith, and means for blowing heated steam and / or hot air into said input passage. 4. The dewatering device according to claim 3, wherein the charging passage further comprises means for adding a coagulant to the concentrated sludge. A dewatering apparatus used in a dewatering method of sludge according to claim 1,
The dehydration apparatus includes a sludge thickener for concentrating the sludge and a screw press for dehydrating the concentrated sludge,
Wherein the sludge thickener is a gravity concentrator for concentrating the sludge by flowing down the sludge,
The screw press machine is characterized in that the screw vanes are not provided on the outer periphery of the rotary shaft constituting the screw shaft over a predetermined length in the axial direction of the middle portion of the screw shaft, Wherein the direct heating chamber has agitation means for agitating the concentrated sludge and means for blowing heated steam and / or hot air. The dewatering device according to claim 5, wherein the stirring means is a stirring device for stirring the sludge with an agitating piece rotating in conjunction with the screw shaft.

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