JP2009165964A - Method and system for dehydrating sludge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a system for dehydrating sludge, in each of which the efficiency when sludge is dehydrated finally is improved to stably obtain dehydrated cake having low water content when the sludge to be generated by treatment of waste water is treated. <P>SOLUTION: The method for dehydrating sludge comprises the steps of: adding a flocculant to the sludge, which is generated from a waste water treatment facility and has 1-5% sludge concentration, and subjecting the flocculant-added sludge to primary flocculation treatment; subjecting the sludge subjected to the primary flocculation treatment to high concentration condensation treatment so that the sludge concentration becomes 6-8%; adding the flocculant to the sludge subjected to the high concentration condensation treatment and subjecting the flocculant-added sludge to secondary flocculation treatment; and dehydrating the sludge which is subjected to the secondary flocculation treatment and has high concentration. The system for dehydrating sludge is also provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for treating sludge, and more particularly to a method for dewatering sewage sludge (organic sludge) generated from wastewater treatment facilities such as sewage treatment and a system (equipment) thereof.

  Generally, wastewater (raw water) such as sewage containing organic substances is treated by a wastewater treatment facility consisting of a first sedimentation tank (first sedimentation tank), a biological treatment tank and a final sedimentation tank (final sedimentation tank). In the first sedimentation basin (raw sludge) in the first sedimentation basin and surplus sludge in the final sedimentation basin will be generated in large quantities, and these sludges have a water concentration of 20-30% (moisture content of 70-80). %)), The volume is reduced by concentration and dehydration treatment. One of the major challenges in this technical field is how to handle it efficiently, including the cost. It has become.

  In the treatment of both sludges, generally the primary sludge is concentrated by gravity to a sludge concentration (hereinafter sometimes referred to simply as “concentration”) of about 4%, and the surplus sludge has undergone biological treatment. Because of its poor nature, it is concentrated to about 4% using a machine other than gravity (centrifugal concentrator, atmospheric concentrator and belt concentrator), and the sludge that has been subjected to separate concentrating treatment is stored in a storage tank. Concentrate to about 4%, and if necessary, digest this mixed sludge to recover and reduce the volume of valuable gases such as methane to make about 2% digested sludge. These mixed sludge or digested sludge Is finally dehydrated to obtain a dehydrated cake having the above-mentioned moisture concentration.

  Conventionally, a screw press has been widely used as an effective dehydrator for performing this dehydration treatment.

  In this screw press, for example, as described in Patent Document 1, a cylindrical screen is divided into a concentration zone on the sludge supply side and a pressure dehydration zone on the cake discharge side in the middle portion, and sludge is supplied from the start end side of the concentration zone. In this type of dehydrator, the screw shaft is rotated and the sludge is concentrated and dewatered while being transferred and passed through the concentration zone and the pressure dewatering zone.

  However, in such a dehydration system in which the concentration zone and the pressure dehydration zone coexist continuously in such a dehydrator, there is a difficulty in that a coagulation operation (treatment) suitable for both the concentration zone and the dehydration zone cannot be performed. It was. That is, in the concentration zone in the dehydrator, it is necessary to form sludge particles into a coagulation floc that can remove a relatively large amount of moisture by a prior agglomeration process, whereas in the sludge squeezing dehydration zone, a prior agglomeration process is required. Dense and strong agglomeration flocks must be formed, but in the above-described conventional dehydration method using a screw press, concentration and squeezing dehydration are performed continuously in the same cylindrical screen, so only a single agglomeration treatment can be performed. In addition, the agglomeration treatment suitable for concentration and dehydration cannot be performed independently.

For this reason, in such prior art, concentration and / or compression dehydration in dehydration becomes insufficient, and the dehydration efficiency as a whole decreases, and as a result, it is difficult to stably obtain a dehydrated cake having a low water content. Had.
Special table 2003-513805 gazette

  The present invention solves such a conventional problem, improves the efficiency of the final dehydration treatment in the treatment of sludge generated by wastewater treatment, and stably obtains a dehydrated cake having a low water content. It was made as.

The structure which makes the summary of the dehydration processing method of the sludge of this invention completed for achieving the said subject is as follows.
(1) A flocculant is added to sludge with a sludge concentration of 1 to 5% generated from a wastewater treatment facility to perform a primary agglomeration treatment, and then the sludge after the primary agglomeration treatment has a sludge concentration of 6 to 8%. High-concentration concentration treatment is performed so that a flocculant is added to the sludge after the high-concentration concentration treatment, followed by secondary agglomeration treatment, and further, the high-concentration sludge subjected to the secondary agglomeration treatment is subjected to dehydration treatment Characterized sludge dewatering method. (Claim 1).
(2) The sludge dewatering method according to (1) above, wherein the high concentration concentration treatment is performed using a belt type concentrator.
(3) The method for dewatering sludge as described in 1 or 2 above, wherein the dewatering treatment is performed using a rotary pressure dehydrator (Claim 3).
(4) The sludge dewatering method according to 1 above, wherein the sludge produced by further digesting the sludge generated from the wastewater treatment facility is used (claim 4).
(5) A primary flocculation treatment tank that performs a primary flocculation treatment by adding a flocculant to sludge having a sludge concentration of 1 to 5% generated from a wastewater treatment facility, and a sludge having a sludge concentration of 6 after the primary concentration treatment. A high concentration concentrator that performs high concentration concentration treatment to ˜8%, and a secondary coagulation treatment tank that adds a flocculant to sludge that has been subjected to high concentration concentration treatment by the high concentration concentrator and performs secondary aggregation treatment And a high-concentration sludge dehydrator for dehydrating the high-concentration sludge that has been subjected to the secondary agglomeration treatment (claim 5).
(6) The sludge dewatering system according to claim 5, wherein the sludge produced by further digesting the sludge generated from the wastewater treatment facility is used (claim 6).
(7) The sludge dewatering system according to (5) or (6) above, wherein the high concentration concentrator is a belt type concentrator.
(8) The sludge dewatering system according to any one of (5) to (7) above, wherein the high-concentration sludge dewatering machine is a rotary pressure dewatering machine.

  In the treatment of sludge generated by wastewater treatment, the efficiency of concentration and dehydration of these sludges is improved, and it becomes possible to obtain a dehydrated cake with a low water content stably and at high cost with high productivity. Has an excellent effect.

  In particular, compared to sludge treatment using a conventional screw press having a concentration zone and a pressure dewatering zone, the concentration step and the dewatering step are separated and independent, and the coagulation treatment suitable for both steps is performed in advance, respectively. High concentration concentration and subsequent dehydration can be carried out extremely efficiently, and the cost of coagulation treatment can be reduced. Moreover, since the load of the high-concentration sludge dehydrator can be greatly reduced, it is possible to reduce energy costs such as electric power.

  As a result of various investigations and analyzes to achieve the above-mentioned problems, the present inventors have found that in a dehydration process using a conventional screw press having a conventional concentration zone and a pressure dewatering zone, Based on the dewatering zone on the cake discharge side, we thought that there was a fundamental cause of the above-mentioned problems in the method of continuously performing sludge concentration and press dewatering.

  Therefore, the present inventors have conducted a dehydration process in which the above-described concentration zone and dehydration zone to which a conventional screw press is applied are integrated continuously, a high concentration treatment (sometimes referred to as secondary concentration treatment) and a high concentration sludge. The present invention has been completed by solving the above-described problems by separating the two steps of dehydration and selecting the optimum treatment, operation and equipment for the purpose of each step.

  Hereinafter, the features of the present invention will be described in detail focusing on the embodiments. FIG. 1 is a process flow diagram showing an embodiment of a sludge dewatering method and dewatering system according to the present invention.

  In the figure, wastewater such as sewage containing various organic substances is first introduced into a wastewater treatment facility comprising a settling tank 1, a biological treatment tank (not shown) and a final settling tank 2, and is purified. A large amount of primary sludge A is generated from the first sedimentation tank 1 of the treatment facility, and a large amount of surplus sludge B is generated from the final sedimentation tank 2 that has undergone biological treatment. The initial sludge A has a sludge concentration of about 1%, and the excess sludge B has a sludge concentration of about 0.6%.

  In the present invention, first, the initial settling sludge A and the excess sludge B are respectively used in the same manner as in the prior art. The initial settling sludge A is obtained by a gravity concentrator 3 such as a settling tank, and the excess sludge B is obtained by a centrifugal concentrator and atmospheric pressure. Each of the mechanical concentrators 4 such as a concentrator and a belt concentrator is subjected to a concentration treatment (primary concentration treatment) to 1 to 5% (for example, 4%) of sludge concentration (hereinafter sometimes referred to simply as concentration). And both the sludge which performed the primary concentration process is sent to the sludge storage tank 5, and both are stored in the state stirred and mixed.

  Next, the mixed sludge C is extracted from the sludge storage tank 5 and sent to the primary flocculation treatment tank 6 to perform the flocculation process. In this primary flocculation tank, flocculant P1 is added and mixed, and sludge flocs that can remove a relatively large amount of water of 2 to 4 mm by agglomerating sludge particles containing organic substances in particular, and the properties of mixed sludge C It is tempered into a form that facilitates the high-concentration concentration process in the next step (hereinafter referred to as the above-mentioned primary concentration process to distinguish it).

  As the flocculant P1, polymer flocculants such as cationic, amphoteric and polyamidine are effective and recommended. In the case of a polymer flocculant, the amount of flocculant P1 added is preferably 0.2% or more, particularly preferably 0.5 to 2%. In addition, when the sludge C and the flocculant P1 are mixed in the primary flocculation tank, it is preferable that the sludge C and the flocculant P1 are mixed with relatively gentle stirring (slow stirring) in order to form the floc.

  Note that the agglomeration treatment here has an advantage that the treatment conditions can be easily selected as compared with the conventional method because only the floc formation in a form suitable for high concentration concentration needs to be considered.

  In the present invention, the mixed sludge C may be directly supplied to the primary flocculation treatment tank 6 as described above, but this is once sent to the digestion tank 10 as indicated by the broken line arrow in FIG. It is possible to perform the treatment and send the digested sludge S having a sludge concentration of about 2% to the primary flocculation treatment tank 6.

  Next, the mixed sludge that has undergone the primary agglomeration treatment, that is, the primary agglomeration sludge D is extracted from the primary agglomeration treatment tank 6 and sent to the high concentration concentrator 7 to concentrate the sludge concentration to a high concentration of 6 to 8%. To process.

  In the present invention, it is important to separate the conventional dewatering process using a screw press having a concentration zone and a dewatering zone into this secondary concentration process and a high-concentration sludge dewatering process described later, and to perform them in separate separate processes. This is one of the features. As a result, as described above, a prior agglomeration process (primary agglomeration process) suitable for the high-concentration concentration process in this step can be performed. That is, the agglomeration process makes the target sludge particles coarse as described above. Since it is tempered and controlled to a sludge floc capable of removing a large amount of water, the free water between the aggregated flocs can be effectively separated and removed by the high concentration concentration treatment here.

  Therefore, sludge supplied at a concentration of 1 to 5% (for example, 4% for normal sludge and 2% for digested sludge) can be easily and stably increased to a high concentration of 6% or more. As a result, the water content of the dewatered cake after the high concentration sludge dewatering treatment can be stably reduced to the target range of 20 to 30%.

  As the high-concentration concentrator used for the high-concentration concentration treatment, it can be said that a belt-type concentrator is particularly preferable from the viewpoint that a concentration of 6% or more can be advantageously realized.

  This belt type concentrator will be described in detail below. FIG. 2 is a schematic cross-sectional view for explaining the configuration of an example of a belt type concentrator used as a high concentration concentrator in the present invention, and FIG. 3 is a view taken in the direction of arrows YY in FIG.

In FIG. 2, reference numeral 5 denotes a belt type concentrator. A pair of rollers 13a and 13b are supported on a frame 14 by a rotating shaft (not shown), and a roller 13b on the discharge side is driven by a drive motor (not shown). The endless belt 12 having a water permeability function straddling the rollers 13a and 13b is caused to travel from the sludge supply side to the discharge side. The endless belt 12 is constituted by a filter body such as a metal mesh-like form or a filter cloth made of synthetic resin such as polyester.
The primary agglomerated sludge D that has been subjected to the agglomeration treatment is extracted from the one agglomeration treatment tank and fed into a supply tank 17 provided on one end side of the endless belt 12 by a sludge pump. Then, the sludge D in the supply tank 17 is agitated and homogenized by the stirrer 17a provided in the supply tank 17, and the sludge liquid is used so that one end side of the endless belt 12 is immersed in the upper layer of the sludge in the supply tank 17. Sludge is supplied onto the endless belt 12 from the sludge supply port 14a while controlling the surface.

  The belt type concentrator 5 has such a sludge supply port 14 a on one end side on the endless belt 12 and a sludge discharge port 14 b for discharging the concentrated sludge on the other end side of the endless belt 12.

  The endless belt 12 is inclined so that the sludge transport side is higher. In order to maintain the sludge concentration after the treatment at a high concentration of 6 to 8%, it is preferable to set the inclination angle of the endless belt 12 to 2 to 12 degrees.

  Further, the frame 14 has a drain port 14c under the endless belt 12 for collecting the permeated permeated water and discharging it to the outside of the frame 4 when the sludge is concentrated as the endless belt 12 advances. is doing.

  The sludge supplied to the upper end of the endless belt 12 from the sludge supply port 14a causes moisture (free water) between the sludge flocs to pass through the endless belt 12 due to its own weight as the endless belt 12 advances. Permeate and concentrate as separation through permeated water.

  This belt type concentrator 11 is a lodging bowl for scraping and removing sludge adhering to the surface of the filter body (filter cloth) constituting the endless belt 12 in order to concentrate sludge D more efficiently. A plurality of sludge separators 20 having a plurality of sludge separators 20 are arranged in a substantially zigzag manner in contact with the upper surface of the endless belt 12 below the plurality of water supply header pipes 22 arranged even if they are arranged substantially perpendicular to the belt conveyance direction. It is arranged. Further, in each sludge separator 20, a cleaning spray nozzle (not shown) connected to a water supply header pipe 22 provided substantially at right angles to the belt conveying direction is accommodated, from which spray water is supplied to the belt 12. By spraying onto the belt, it is possible to reliably clean the upper surface of the belt immediately after the removal of sludge.

  The sludge on the endless belt 12 thus concentrated is scraped off by the scraper 18 and discharged as a high-concentration sludge from the sludge discharge port 14b and stored in the storage tank as necessary, and then to the next step. Will be sent. The permeated water separated from the sludge is recovered from the drain port 14c to a separation liquid tank (not shown), and the supernatant is transferred to a washing water tank (not shown) from which the endless water is transferred. It is sent to a washing nozzle 19 installed toward the back surface of the belt 12 and reused as washing water for washing away the sludge adhering to and remaining on the belt 12.

  Now, in the present invention, the high-concentration sludge E concentrated at a high concentration of 6 to 8% by the high-concentration concentrator 7 such as the belt type concentrator described above is further sent to the secondary flocculation treatment tank 8 and the flocculant P2 is supplied. Addition, mixing, and agglomeration treatment (secondary agglomeration treatment) are performed again, and the sludge particles after the concentration treatment are agglomerated to form a relatively small, strong and dense sludge floc of 0.5 to 3 mm. This is for the purpose of refining the form in order to sufficiently withstand the dehydration pressure in the high-concentration sludge dewatering process and effectively promote the dewatering operation.

  As the flocculant P2, polymer flocculants such as cationic, amphoteric and polyamidine are effective and recommended as in the case of the above-mentioned primary flocculant treatment. An inorganic flocculant such as polyferric sulfate may be used.

  In addition, when the sludge E and the flocculant P2 are mixed in the secondary flocculation tank, it is preferable to mix them with relatively high agitation (rapid agitation) in order to form the floc.

  In addition, since only the floc of the form suitable for squeezing and dehydrating concentrated sludge should be considered also in the agglomeration treatment here, there is an advantage that the treatment conditions can be easily selected as compared with the conventional case.

  Then, the sludge that has undergone the coagulation treatment in the secondary coagulation tank 8 is extracted from the coagulation tank 8 and supplied to the high concentration sludge dewatering machine 7 as the secondary coagulation treatment sludge F, where the high concentration sludge dehydration treatment is performed. The dehydrated cake G has a moisture content of 70 to 80% (water content: 20 to 30%).

  In the present invention, the conventional dehydration treatment using a screw press having a concentration zone and a compression dewatering zone is separated into the high concentration concentration treatment in the above step and the high concentration sludge dehydration treatment in this step, and each is made an independent step. There is a big feature. As a result, a prior agglomeration process (secondary agglomeration process) suitable for the high-concentration sludge dewatering process in this step becomes possible. That is, the agglomeration process makes the target sludge particles relatively small and strong as described above. Therefore, the internal water in the sludge floc can be effectively separated and removed by this dehydration treatment.

  Therefore, the final coagulation sludge having a high concentration of 6 to 8% obtained in the previous high concentration concentration treatment can stabilize the dehydrated cake having a low water content of 70 to 80% by this final dehydration treatment. Can be obtained.

As the high-concentration sludge dehydrator 9, a known dehydrator can be used. This technology increases the concentration to 6-8% with a high-concentration concentrator and reduces the water removal load of the high-concentration sludge dehydrator, so-called filtration load. Therefore, a dehydrator based on filtration is effective. The rotary pressure dehydrator shown below is particularly excellent as a filter dehydrator in terms of energy saving and space saving, and further improves performance. It is particularly preferable to use a rotary pressure dehydrator from the viewpoint of productivity.
This rotary pressure dehydrator will also be described in detail below.

  FIG. 4 is a schematic side view for explaining the configuration of an example of a rotary pressurization dehydrator used as a dehydrator in the present invention, and FIG. 5 is a schematic longitudinal sectional view through point O in FIG.

  In the figure, the rotary pressure dehydrator 9 is provided with a drive shaft 32 that is rotated at a rotational speed of 0.5 to 1.3 rpm by a drive device with a speed reducer (not shown). A disk-shaped first filter plate 37 and a second filter plate 38 facing each other through the member 33 are fixed. The first filter plate 37 and the second filter plate 38 are configured to rotate in the rotational direction indicated by the arrow by the drive shaft 32. Moreover, the 1st filtration plate 37 and the 2nd filtration plate 38 have many water permeation | transmission holes (not shown), and both the filtration plates 37 and 38 and the drive shaft 32 side edge part of both the filtration plates are carried out. A dehydration treatment chamber 41 is formed by the annular inner ring spacer 34 disposed and the annular outer ring spacer 35 disposed concentrically with the inner ring spacer 34 at the circumferential ends of the two filter plates.

  The outer ring spacer 35 is provided with a partition spacer 36 having a concave curved surface in close contact with the outer peripheral surface of the inner ring spacer 34 on the center side of the outer ring spacer 35. The partition spacer 36 is formed in a bifurcated shape including an upper partition spacer 36a and a lower partition spacer 36b at a lower position across the space 36c. A sludge inlet 41 a that opens in the lateral direction is formed below the lower partition spacer 36 b of the partition spacer 36.

  In addition, a dehydrated cake discharge portion 40 that opens in the horizontal direction is provided above the upper partition spacer 36 a of the partition spacer 36. The dewatering treatment chamber 41 has a filtration zone 41b for filtering conditioned sludge flowing in from the sludge inlet 41a in order from the sludge inlet 41a toward the dehydrated cake discharger 40, and the filtered water is removed. It is divided into a pressure dewatering zone 41c for pressing and dewatering the sludge. The sludge inlet 41a is attached with a sludge inlet 39a that opens downward, and a sludge supply unit 39 that supplies the sludge to the sludge inlet 41a via a sludge flow path.

  Further, a back pressure plate 45 for applying a back pressure to the squeezed and dewatered sludge in the squeezing and dewatering zone 41 c of the dewatering treatment chamber 41 by an actuator or the like is provided vertically at the discharge port 40 a of the dewatered cake discharge unit 40. ing. In the dehydration chamber 41, the edges are in acute contact with the opposing surfaces (inner side surfaces) of the first filter plate 37 and the second filter plate 38, and the first filter plate 37 and the second filter plate 38. Three scrapers 41d (six on each side) are provided for scraping off the fine particle lump in the sludge and the dehydrated cake adhering to the opposing inner surfaces. A drain pipe 44 that protrudes downward is provided at the lower part of each of the first cover 42 and the second cover 43, and is supplied into the dehydration treatment chamber 41 through the sludge supply part 39 and the sludge inlet 39a. The water in the sludge discharged into the first cover 42 and the second cover 43 through the water permeation holes 37 a and 38 a provided in the first and second filter plates 37 and 38 is discharged from the drain pipe 44. It is designed to be drained outside the machine.

When the secondary coagulation-treated sludge F is dehydrated by such a rotary pressure dehydrator, the sludge F extracted from the secondary coagulation treatment tank 8 is extracted at a maximum of 100 kPa (about 1.0 kgf) by a sludge injection pump (not shown). / Cm ² ) and is rotated at a slow speed of 0.5 to 1.3 rpm through the sludge inlet 39a, the sludge flow path, and the sludge inlet 41a that are opened to the lower side of the sludge supply section 39. Dehydration is performed by continuously supplying to the lower filtration zone 41 b of the dehydration treatment chamber 41.

  And the sludge supplied to the filtration zone 41b below the dehydration chamber 41 is filtered in this filtration zone 41b, and the fluidity is gradually lost. The sludge whose fluidity has been lowered in this manner is formed by gradually forming a cake layer on the surfaces of the disk-shaped first filter plate 37 and the second filter plate 38 provided with a large number of water permeation holes. 37, The second filtration plate 38 moves to the pressing and dehydrating zone 41c side by rotation. The cake is formed on the surfaces of the first filter plate 37 and the second filter plate 38, so that the trapping of solid matter is improved, so that the filtrate is cleaned.

The sludge in the compressed dewatering zone 41c region has a maximum back pressure of 600 kPa (about 6.0 kgf / cm ² ) by controlling the pressing force of the back pressure plate 45 provided at the discharge port 40a of the dewatered cake discharge unit 40. Continue to be held at a constant pressure (which is adjustable). The sludge that has lost its fluidity is squeezed and dehydrated by the shearing force generated by the first filter plate 37 and the second filter plate 38 and the back pressure generated by the back pressure plate 45. Finally, the dehydrated cake G having a low water content that has been pressed and dehydrated is pushed out of the back pressure plate 45 and discharged from the dehydrated cake discharge unit 40 to the outside of the machine.

  By using such a rotary pressure dehydrator for the dehydration treatment of the secondary coagulation sludge F in the present invention, the dewatered cake pieces scraped by the scraper 41d in the sludge dewatering process as described above are separated from the scraper 41. Is applied to the outer ring spacer 35 and moves toward the outer ring spacer 35, so that the density of the dewatered cake at the position in the dewatering chamber 41 away from the rotation center of the first and second filter plates 37 and 38 is increased. The degree of reduction can be reduced. Thereby, the squeezing force distribution over the entire width of the filtration surfaces of the first and second filter plates 37 and 38 is equalized, and the filtration function over the entire width of the filtration surface is improved. Moreover, in this rotary pressure dehydrator, the fine particle lump and the dehydrated cake in the sludge adhering to each of the opposing inner surfaces of the first filter plate 37 and the second filter plate 38 are fastened at both ends and are not bent. The edges are scraped by the scraper 41d that makes acute contact with the inner surfaces of the first filter plate 37 and the second filter plate 38, and clogging of the water permeable holes is effectively prevented over the entire width of the filter surface. Therefore, sludge can be efficiently dehydrated.

In the embodiment described above, as the target sludge having a sludge concentration of 1 to 5% subjected to the primary agglomeration treatment, the first settling sludge A and the excess sludge B are respectively used as the gravity concentrator 3 and the mechanical concentration. Although the thing which mixed and stored these after primary concentration with the machine 4 was demonstrated, not only this but what mixed both sludges A and B beforehand with the mechanical type concentrator 4 collectively concentrated Of course, it is also possible to use a primary concentrated sludge A or surplus sludge B that is primarily concentrated.
(Experimental example)
In order to clarify the effect of the present invention, the following experiment was conducted.

  In a beaker test, sludge (mixed raw sludge) adjusted to a concentration of 3% was prepared. As an example of the present invention, 0.5% amphoteric polymer flocculant (Shinko Flock C6228) was added to the sludge. After the next flocculation treatment, this is concentrated to a high concentration of 6.4%, and 0.2% of an amphoteric polymer flocculant (Shinko Flock C6228) is added to the high concentration sludge to obtain a secondary flocculation treatment. After dehydration, a high-concentration sludge dehydration operation was carried out to obtain a dehydrated cake.

    On the other hand, as a comparative example, 0.7% of the same flocculant was added to the same sludge adjusted to a concentration of 3% as described above, and after agglomeration treatment, a conventional dehydration operation was performed to obtain a dehydrated cake. When the moisture content of the cake was measured, it was 80.3%.

  Therefore, according to the example of the present invention, compared with the comparative example, the difference in water content is drastically reduced to 4.6% even though the total addition amount of the flocculant is 0.7%. It was found that the excellent effect of the present invention was confirmed.

It is a flowchart explaining embodiment of the sludge processing method and sludge processing system of this invention. It is a schematic sectional drawing explaining the structure of the belt-type concentrator used for the concentration process of this invention. It is a YY arrow line view of FIG. 2 explaining the structure of the belt type concentrator. It is a schematic side view explaining the structure of the rotary pressurization dehydrator used for the dehydration process of this invention. It is a schematic longitudinal cross-sectional view which passes along the O point of FIG. 4 explaining the structure of the rotation pressure dehydrator.

Explanation of symbols

1: First settling tank 2: Final settling tank 3: Gravity type concentrator
4: Mechanical concentrator 5: Storage tank 6: Primary coagulation treatment tank 7: High concentration concentrator 8: Secondary coagulation treatment tank 9: High concentration sludge dehydrator
A: Initial settling sludge B: Surplus sludge C: Mixed sludge
D: Primary coagulated sludge E: High concentration sludge F: Secondary coagulated sludge G: Dehydrated cake

The structure which makes the summary of the dehydration processing method of the sludge of this invention completed for achieving the said subject is as follows.
(1) The sludge generated from the wastewater treatment facility is subjected to a primary concentration treatment so that the sludge concentration is 1 to 5%, and a polymer flocculant is added to the sludge after the primary concentration treatment to remove sludge particles. Perform primary agglomeration treatment to make a floc of 4 mm in size, and then increase the sludge transport destination side of the endless belt so that the sludge after the primary agglomeration treatment has a sludge concentration of 6-8%. High-concentration concentration treatment is performed using a belt-type concentrator disposed at an inclination angle of 2 to 12 degrees (but not including 2 degrees), and then a flocculant is added to the sludge after the concentration treatment to produce sludge particles. A sludge dewatering method characterized by performing a secondary agglomeration treatment to form a floc having a size of 0.5 to 3 mm, and further subjecting the high-concentration sludge subjected to the secondary agglomeration treatment to a dehydration treatment based on filtration. . (Claim 1).
(2) The method for dewatering sludge as described in 1 above, wherein the dewatering is performed using a rotary pressure dehydrator. (Claim 2).
(3) The sludge dewatering method according to 1 above, wherein the sludge generated from the wastewater treatment facility is further digested.
(4) Adding a polymer flocculant to the primary concentrator that performs the primary concentration treatment so that the sludge generated from the wastewater treatment facility has a sludge concentration of 1 to 5%. A primary flocculation treatment tank for performing a primary flocculation process that makes sludge particles into flocs having a size of 2 to 4 mm, and a high concentration concentration treatment of the sludge after the primary flocculation process so that the sludge concentration is 6 to 8%. The belt-type concentrator disposed at an inclination angle of 2 to 12 degrees (excluding 2 degrees) so that the sludge transport destination side of the endless belt is high, and the high-concentration concentration by the high-concentration concentrator A secondary agglomeration treatment tank for performing a secondary agglomeration treatment in which a flocculant is added to the sludge that has been treated to make sludge particles into flocs having a size of 0.5 to 3 mm; A high-concentration sludge dehydrator based on filtration. Dewatering system sludge, characterized in that (claim 4). (5) The sludge dewatering system as described in (4) above, wherein the sludge generated from the wastewater treatment facility is further digested.
(6) The sludge dewatering system according to (4) or (5) above, wherein the high-concentration sludge dewatering machine is a rotary pressure dewatering machine.

  As the high concentration concentrator used for the high concentration concentration treatment, a belt type concentrator is adopted from the viewpoint of advantageously realizing a concentration of 6% or more.

The endless belt 12 is inclined so that the sludge transport side is higher.
In order to maintain the sludge concentration after the treatment at a high concentration of 6 to 8%, it is necessary to set the inclination angle of the endless belt 12 to 2 to 12 degrees (excluding 2 degrees).

  The belt type concentrator 5 is a lodging bowl for scraping and removing sludge adhering to the surface of the filter body (filter cloth) constituting the endless belt 12 in order to concentrate sludge D more efficiently. A plurality of sludge separators 20 having a plurality of sludge separators 20 are arranged in a substantially zigzag manner in contact with the upper surface of the endless belt 12 below the plurality of water supply header pipes 22 arranged even if they are arranged substantially perpendicular to the belt conveyance direction. It is arranged. Further, in each sludge separator 20, a cleaning spray nozzle (not shown) connected to a water supply header pipe 22 provided substantially at right angles to the belt conveying direction is accommodated, from which spray water is supplied to the belt 12. By spraying onto the belt, it is possible to reliably clean the upper surface of the belt immediately after the removal of sludge.

  Then, the sludge that has undergone the coagulation treatment in the secondary coagulation tank 8 is extracted from the coagulation tank 8 and supplied to the high concentration sludge dewatering machine 9 as the secondary coagulation treatment sludge F, where the high concentration sludge dehydration treatment is performed. The dehydrated cake G has a moisture content of 70 to 80% (water content: 20 to 30%).

  As the high-concentration sludge dewatering machine 9, this technology increases the concentration to 6 to 8% with the high-concentration concentrator, and reduces the water removal load in the high-concentration sludge dewatering machine, so-called filtration load. A dehydrator based on filtration is effective and shall be used. The rotary pressure dehydrator shown below is particularly excellent as a filter dehydrator in terms of energy saving and space saving, and further improves performance. It is particularly preferable to use a rotary pressure dehydrator from the viewpoint of productivity. This rotary pressure dehydrator will also be described in detail below.

The structure which makes the summary of the dehydration processing method of the sludge of this invention completed for achieving the said subject is as follows.
(1) The sludge generated from the wastewater treatment facility is subjected to primary concentration treatment so that the sludge concentration becomes 1 to 5%, and a polymer flocculant is added to the sludge after the primary concentration treatment , The primary coagulation treatment is performed to make a floc of 2 to 4 mm suitable for removing free water between the sludge flocs after flocculation in the high concentration concentration treatment in the next step , and then the sludge after the primary flocculation treatment is A belt-type concentrator disposed at an inclination angle of 2 to 12 degrees (excluding 2 degrees) so that the sludge transport side of the endless belt is increased so that the sludge concentration is 6 to 8%. Using a high concentration concentration treatment, and then adding a flocculant to the sludge after the concentration treatment, the sludge particles, 0.5 ~ suitable for removal of internal water in the sludge floc after aggregation in the dehydration treatment of the next step Perform secondary agglomeration treatment with 3 mm flocs and further secondary agglomeration Dehydration treatment methods sludge, characterized in that which processes the basic and was dehydrated filtered in a high concentration sludge Been (claim 1).
(2) The sludge dewatering method according to (1) above, wherein the dewatering treatment is performed using a rotary pressure dehydrator.
(3) dehydration treatment methods sludge according to the above 1 that is targeted to the sludge which has been subjected to further digestion treatment in sludge generated from wastewater treatment facilities (claim 3).
(4) Adding a polymer flocculant to the primary concentrator that performs the primary concentration treatment so that the sludge generated from the wastewater treatment facility has a sludge concentration of 1 to 5%. the sludge particles, and the primary flocculation treatment tank to perform high density concentration treatment primary flocculating size of flocs and eggplant 2~4mm suitable for removal of free water between your Keru sludge flocs after aggregation enough next Engineering The sludge after the primary agglomeration treatment is concentrated at a high concentration so that the sludge concentration is 6 to 8%, and the sludge transport destination side of the endless belt is increased so that the inclination angle is 2 to 12 degrees (however, 2 A belt-type concentrator disposed in a high-concentration concentrator and sludge that has been subjected to high-concentration concentration processing by the high-concentration concentrator, and then adding a flocculant, large of 0.5~3mm suitable for the removal of internal water in the sludge flocs Including a secondary agglomeration treatment tank for performing secondary agglomeration treatment as a floc and a high-concentration sludge dehydrator based on filtration for dehydrating the high-concentration sludge subjected to the secondary agglomeration treatment. A sludge dewatering treatment system (claim 4).
(5) The sludge dewatering system according to (4) above, wherein the sludge generated from the wastewater treatment facility is further digested.
(6) The sludge dewatering system according to (4) or (5) above, wherein the high-concentration sludge dewatering machine is a rotary pressure dewatering machine.

The structure which makes the summary of the dehydration processing method of the sludge of this invention completed for achieving the said subject is as follows.
(1) The sludge generated from the wastewater treatment facility is first concentrated so that the sludge concentration becomes 1 to 5%, and a polymer flocculant is added to the sludge after the first concentration treatment and mixed by slow stirring. and, the sludge particles, performs primary flocculating size of flocs and eggplant 2~4mm suitable for removal of free water between sludge flocs after high concentration concentration treatment definitive aggregation of the next step, then the primary agglomeration The treated sludge is disposed at an inclination angle of 2 to 12 degrees (excluding 2 degrees) so that the sludge transport side of the endless belt is high so that the sludge concentration is 6 to 8%. High concentration using a belt type concentrator, then adding a polymer flocculant to the sludge after concentration treatment and mixing with rapid stirring, and sludge particles after the aggregation in the dehydration process of the next step flocs in the primary aggregation process suitable for the removal of internal water of the inner Performs the size of flocs and eggplant secondary agglomeration process small 0.5~3mm compared, characterized in that it further subjected to basic dewatering process is filtered in a high concentration sludge was secondary agglomeration sludge A dehydration treatment method (claim 1).
(2) The sludge dewatering method according to (1) above, wherein the dewatering treatment is performed using a rotary pressure dehydrator.
(3) The sludge dewatering method according to 1 above, wherein the sludge generated from the wastewater treatment facility is further digested.
(4) Adding a polymer flocculant to the primary concentrator that performs the primary concentration treatment so that the sludge generated from the wastewater treatment facility has a sludge concentration of 1 to 5%. Mix by slow agitation and perform primary coagulation treatment to make sludge particles into flocs with a size of 2 to 4 mm suitable for removing free water between coagulated sludge flocs in the high concentration concentration process of the next step 1 The secondary agglomeration tank and sludge after the primary agglomeration treatment are concentrated at a high concentration so that the sludge concentration is 6-8%, and the sludge transport destination side of the endless belt is inclined at 2-12 degrees. Add a polymer flocculant to the belt-type concentrator disposed at the corner (however, not including 2 degrees) and sludge that has been subjected to high-concentration concentration processing by the high-concentration concentrator , and mix by rapid stirring. Sludge flocs after flocculation of sludge particles in the dehydration process of the next process And secondary agglomeration treatment tank to perform the size of flocs and eggplant secondary agglomeration process small 0.5~3mm compared to flocs in the primary aggregation process suitable for the removal of internal water, secondary aggregation treatment A sludge dewatering system comprising a filtration-based high-concentration sludge dewatering machine for dewatering the high-concentration sludge performed.
(5) The sludge dewatering system according to (4) above, wherein the sludge generated from the wastewater treatment facility is further digested.
(6) The sludge dewatering system according to (4) or (5) above, wherein the high-concentration sludge dewatering machine is a rotary pressure dewatering machine.

Claims (8)

  A flocculant is added to sludge having a sludge concentration of 1 to 5% generated from a wastewater treatment facility to perform a primary agglomeration treatment, and then the sludge after the primary agglomeration treatment has a sludge concentration of 6 to 8%. The sludge is characterized in that it is subjected to a high concentration concentration treatment, then a flocculant is added to the sludge after the concentration treatment, a secondary agglomeration treatment is performed, and a high concentration sludge subjected to the secondary agglomeration treatment is further subjected to a dehydration treatment. Dehydration method.   The sludge dewatering method according to claim 1, wherein the high concentration concentration treatment is performed using a belt type concentrator.   The method of dewatering sludge according to claim 1 or 2, wherein the dewatering process is performed using a rotary pressure dehydrator.   The sludge dewatering method according to claim 1, wherein the sludge generated by the wastewater treatment facility is further digested.   A primary flocculation treatment tank that performs a primary flocculation treatment by adding a flocculant to sludge with a sludge concentration of 1-5% generated from a wastewater treatment facility, and a sludge concentration after the primary concentration treatment is 6-8%. A high-concentration concentrator for performing high-concentration concentration so as to become, a secondary flocculation treatment tank for adding a flocculant to sludge that has been subjected to high-concentration concentration processing by the high-concentration concentrator, and performing a secondary flocculation treatment, A sludge dewatering system, comprising: a high-concentration sludge dewatering machine that dehydrates the high-concentration sludge subjected to the next coagulation treatment.   The sludge dewatering system according to claim 5, wherein the sludge generated from the wastewater treatment facility is further digested.   The sludge dewatering system according to claim 5 or 6, wherein the high concentration concentrator is a belt type concentrator.   The sludge dewatering system according to any one of claims 5 to 7, wherein the high-concentration sludge dewatering machine is a rotary pressure dewatering machine.

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