Dehydration aid adding device and dehydration aid adding method

Abstract

To provide a device and a method for adding a dehydration auxiliary material capable of effectively utilizing fibers to be disposed of as the dehydration auxiliary material by: feeding with a compressed air the dehydration auxiliary material formed from fibers generated in a process for producing a nonwoven fabric and the like by fibrillating it with a fibrillator; and mixing and stirring it with sludge.SOLUTION: A device for adding and mixing a dehydration auxiliary material to sludge includes: a fibrillator that fibrillates fibers to form the dehydration auxiliary material; a connecting part, connected to the fibrillator, for feeding the dehydration auxiliary material with a compressed air; and a sludge mixing tank that is connected to the connecting part and mixes and stirs a sludge that is flowing by a supplied compressed air with the dehydration auxiliary material, thereby uniformly mixing the sludge with the dehydration auxiliary material without installing a separate large stirring device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a dehydration aid adding device and a dehydration aid adding method for effectively dehydrating difficult-to-dehydrate sludge generated in a sewage treatment plant. [Background technology]

[0002] Conventionally, difficult-to-dewater sludge, such as excess sludge and digested sludge, generated at wastewater treatment plants has low fiber content and poor dewaterability. Excess sludge is produced by biological treatment, where organic matter (e.g., fiber) in the sludge is converted by microorganisms. Digested sludge is produced by anaerobic digestion, where organic matter (e.g., fiber) in the sludge is decomposed by anaerobic bacteria. Therefore, difficult-to-dewater sludge before dewatering contains only a small amount of fiber. Because fiber in sludge functions as a nucleus for coagulation and also has the effect of forming water channels within the flocs during dewatering, sludge with reduced fiber content cannot be properly coagulated or dewatered, resulting in poor dewaterability. Therefore, dewatering methods have been proposed that compensate for the reduced fiber content by mixing fibrous materials or plant materials such as sawdust and rice husks as dewatering aids. The use of fibrous materials as dewatering aids has been shown to consistently produce dewatered cakes with low moisture content with the addition of small amounts, and to improve the peelability of the dewatered cakes in pressurized dewatering.

[0003] Patent Document 1 discloses a technology in which a fibrous dewatering aid, such as a material for manufacturing nonwoven fabric, is fed into a hopper using compressed air, and then supplied to a treatment tank such as a sludge storage tank and mixed with the sludge in the tank.

[0004] Patent Document 2 discloses a technology in which powdered or granular materials such as dewatering aids are pumped using the ejector action of pressurized air, and then the powdered or granular materials and pressurized air are pressurized and sprayed through a nozzle, and mixed with the supplied sludge in a mixing section.

[0005] Patent Document 3 discloses a technology in which waste paper is dry-cleaned, then transported with air and mixed with sludge incineration ash. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2020-179336 [Patent Document 2] Special Publication No. 01-10255 [Patent Document 3] Japanese Patent Application Publication No. 06-63528 Summary of the Invention [Problem to be solved by the invention]

[0007] When using conventional plant materials as dewatering aids, the dewatering aids are lightweight, so a mixing device is required to mix them with the sludge that contains a lot of water before dewatering. In particular, when supplying them to a large sludge storage tank, a large mixing device is required, and when mixing in a separate mixing tank, a dedicated mixing tank, mixing and transport equipment, and installation space are required. Another issue is that the sludge that remains in the sludge storage tank will decay, reducing the dewatering efficiency of the dewatering equipment installed downstream.

[0008] In Patent Document 1, the hopper is of a cyclone type, so the dewatering aid in the hopper settles downward and is then supplied to a treatment tank such as a sludge storage tank. However, the compressed air that has delivered the dewatering aid is discharged upward from the central separator, so only the dewatering aid is supplied to the treatment tank, and the energy of the compressed air is not used to agitate the dewatering aid.

[0009] In Patent Document 2, a nozzle is provided to supply powder and granular material into the mixing section, which may cause the supplied sludge to flow back into the nozzle and cause blockage of the sealed transport pipe.Furthermore, in addition to the nozzle, a turbulence generator with a variable cross-sectional area is provided inside the mixing tank, making the device structure complex.

[0010] Patent Document 3 describes a technique in which defibrated fibers are mixed with sludge incineration ash, then supplied to a stirring tank and mixed with stirring blades, and is not a technique in which stirring is performed using air obtained from a blower blade built into the defibrator.

[0011] The present invention provides a dehydration aid adding device and a dehydration aid adding method that defibrates scraps (fibrous materials) generated during the manufacturing process of nonwoven fabrics, etc., reuses the defibrated material as a dehydration aid, and adds the defibrated material, which is pressurized by compressed air, to sludge and then mixes them uniformly. [Means for solving the problem]

[0012] The present invention relates to an apparatus for adding and mixing a dewatering aid to sludge, and includes a defibrator that defibrates fibrous materials to form a dewatering aid, a communication part that is connected to the defibrator and that pumps the dewatering aid with compressed air, and a supply part that is connected to the communication part and that supplies the dewatering aid. The aforementioned By providing a sludge mixing tank in which sludge fluidized by compressed air is mixed and stirred together with dewatering aids, the sludge and dewatering aids can be mixed efficiently, producing mixed sludge in which the dewatering aids are uniformly mixed.

[0013] The defibrator is a dry type defibrator, and is connected at its other end to a communication part connected to the bottom of the sludge mixing tank. It is also equipped with a blower blade that generates compressed air to be supplied to the communication part. This allows the compressed air generated within the defibrator to be used for pressurizing the dewatering aid and mixing and stirring the sludge and dewatering aid, so there is no need to provide a separate compressed air supply source for generating compressed air.

[0014] The sludge mixing tank is equipped with an air diffuser pipe installed internally at the bottom and communicating with the communication section, partition plates extending upward with specified gaps at the bottom and top, and a sludge supply section to which circulating sludge is supplied by compressed air supplied from the air diffuser pipe.By forming the air diffuser pipe outlet hole in a position not facing the sludge supply section, the sludge and dewatering aid can be mixed by air lift within the sludge mixing tank, improving the miscibility of the dewatering aid and sludge and making it possible to improve the dewaterability of the sludge.

[0015] By connecting a return section that returns a portion of the dewatering aid to the defibrator to the communication section, the dewatering aid can be repeatedly defibrated, improving defibration efficiency, and by allowing compressed air to be circulated, excessive supply of compressed air to downstream equipment can be prevented, and an appropriate amount can be supplied at all times.

[0016] In the dewatering aid addition method in which a dewatering aid is added and mixed with sludge, after defibrating the fibrous material to form a dewatering aid, the dewatering aid is pressure-fed to a sludge mixing tank by compressed air and supplied to the sludge mixing tank. The aforementioned By mixing and stirring the sludge fluidized by compressed air with dewatering aids, mixed sludge with uniformly mixed dewatering aids can be produced in the early stages of the dewatering process, thereby improving the dewatering efficiency in the dewatering machine. [Effects of the Invention]

[0017] The dewatering aid adding device and dewatering aid adding method according to the present invention mix and stir the dewatering aid formed by defibrating fibrous materials with sludge in a sludge mixing tank to produce mixed sludge. Since the sludge in the tank is fluidized by compressed air obtained from the defibrator, a large mixing tank equipped with an agitator is not required. This reduces the installation area and running costs, making it possible to provide a compact and inexpensive device. In addition, since the dewatering aid after defibration is constantly pumped by compressed air, it does not form clumps and prevents clogging of the communication part, allowing the dewatering aid to be continuously supplied to the sludge mixing tank. A check valve is provided in the communication part to maintain the fluid flow in a fixed direction, so sludge does not flow back, allowing continuous operation. In addition, the sludge mixture The sludge in the tank is constantly moving due to the compressed air supplied, so it does not accumulate at the bottom. When compressed air is supplied, oxygen is taken in, and the sludge mixture The tank also functions as an aeration tank, preventing sludge from decaying. Microorganisms in the sludge that have absorbed oxygen absorb phosphorus, preventing the re-elution of phosphorus, and reducing the phosphorus concentration in the dehydrated filtrate discharged from the dehydrator. Furthermore, the fibers used for defibration are those that would otherwise be discarded, such as scraps of nonwoven fabric, which also contributes to resource recycling. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a flow diagram of a sludge treatment method according to the present invention. [Figure 2] FIG. 2 is a schematic diagram of a dehydration aid adding device. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. 10 is an explanatory view showing the sludge mixing tank as viewed from the front. [Figure 6] FIG. 6 is an explanatory view showing the sludge mixing tank as seen from the direction of the arrow shown in FIG. 5. DETAILED DESCRIPTION OF THE INVENTION

[0019] FIG. 1 is a flow diagram of the sludge treatment method according to the present invention. In this embodiment, the system comprises a reaction tank 1 in which influent water flowing into a sewage treatment plant is circulated in an endless circulating water channel while being aerated and stirred for biological treatment, a final sedimentation tank 2 in which treated water supplied from the reaction tank 1 is separated by settling and the supernatant is disinfected before being discharged into a river or the like, a dehydration aid adding device 3 that adds and mixes a dehydration aid with the excess sludge supplied from the final sedimentation tank 2, and a dehydrator 4 that dehydrates the mixed sludge to which the dehydration aid has been added and mixed to produce a dehydrated cake. Note that, as shown by the dashed line, the dehydration aid adding device 3 is also provided upstream of the dehydrator 4 when the activated sludge in the reaction tank 1 is directly supplied to the dehydrator 4 using the direct dehydration method.

[0020] In this embodiment, the dewatering aid is added to and mixed with excess sludge generated at a treatment plant that uses the OD method (oxidation ditch method), in which influent water and activated sludge are mixed and circulated using an aeration device in a reaction tank 1 with an endless channel shape.However, the method can also be applied to sludge that is difficult to dewater, such as digested sludge, and sludge that is easy to dewater, such as mixed raw sludge.

[0021] FIG. 2 is a schematic diagram of the dehydration aid adding device. The dewatering aid adding device 3 is composed of a defibrator 5, a sludge mixing tank 6, and a communication section 7 that connects them. The defibrator 5 defibrates clumped fibrous material to form defibrated material that is in a state similar to untangled short fibers. In this embodiment, scraps (fibrous material) generated during the manufacturing process of nonwoven fabrics and the like are defibrated to form defibrated material, and the defibrated material formed is used as the dewatering aid. In order to improve the defibration efficiency of the fibrous material, it is desirable to install a constant volume feeder (not shown) upstream of the defibrator 5 and feed a constant volume of fibrous material to the defibrator 5.

[0022] The sludge mixing tank 6 mixes and agitates the dewatering aid (defibrated material) formed by the defibrator 5 with excess sludge, activated sludge, etc. shown in Figure 1 to produce mixed sludge. An air diffuser 9 having a large number of jet holes 20 is provided below the sludge mixing tank 6, and is configured so that the sludge and dewatering aid supplied into the tank can be mixed and agitated by air jetted from the jet holes 20. The sludge mixing tank 6 uses a conventional sludge storage tank and stores and mixes the sludge.

[0023] Between the defibrator 5 and the sludge mixing tank 6, a supply pipe (communication part 7) is provided, one end of which is connected to the defibrator 5 and the other end of which is connected to the sludge mixing tank 6, so that the dewatering aid formed by the defibrator 5 can be supplied to the sludge mixing tank 6. A check valve 10 is installed in the communication part 7 to prevent backflow from within the sludge mixing tank 6.

[0024] The other end of the communication part 7 connected to the sludge mixing tank 6 is connected to an air diffuser 9 inside the tank, and the dewatering aid supplied from the communication part 7 and compressed air for pumping the dewatering aid are supplied from the nozzle 20.

[0025] The communication section 7 is connected to a return section 12, one end of which is connected to the fibrous material supply section 11, so that the defibrated fibrous material can be returned to the defibrator 5. This allows the fibrous material to be repeatedly defibrated, making it possible to form dewatering aids of the desired size and improving their mixability with the sludge in the sludge mixing tank 6. As a result, it is possible to improve the coagulation of the sludge in the coagulation mixing tank (not shown) placed upstream of the dehydrator and the dehydration efficiency in the dehydrator.

[0026] In this embodiment, the communication section 7 uses a supply pipe and is configured to connect to the defibrator 5 and the sludge mixing tank 6, respectively, but the defibrator 5 and sludge mixing tank 6 may be unitized and connected to each other without using a supply pipe. Furthermore, the fibrous material that is defibrated to form the dewatering aid is not limited to scraps of nonwoven fabric, but may also be scraps of old clothes, used filter cloth, cutting scraps of automobile skin materials, etc. Generally, recycling items that would otherwise be discarded is environmentally friendly, so it is desirable to make effective use of waste materials.

[0027] FIG. 3 is a partial cross-sectional front view of the fiberizing machine, and FIG. 4 is a vertical cross-sectional side view of the fiberizing machine. As shown in Figure 3, the defibrator 5 has a defibrating chamber 13 inside a rectangular casing 14, and is configured so that after the fibers supplied from a supply port 22 (at the back side of Figure 3 and on the right side of Figure 4) of the defibrating chamber 13 are defibrated in the defibrating chamber 13, the dewatering aid (defibrated material) is discharged from a communication part 7 connected to the side of the casing 14. A blower blade 17 driven by a driver 16 is housed inside the defibrating chamber 13, and by driving the driver 16, the blower blade 17 can be rotated at high speed.

[0028] Defibrating teeth 18 are formed continuously in the circumferential direction on the inner wall of the defibrating chamber 13, and the fibrous material comes into contact with the defibrating teeth 18 and is defibrated by the high-speed jet airflow (compressed air) generated in the direction of rotation when the blower blades 17 are rotated at high speed. The defibrating teeth 18 have a sawtooth shape as shown in Figure 4, and the high-speed jet airflow (compressed air) collides with the clumps of fibrous material swirling inside the defibrating chamber 13, cutting the long fibers and defibrating them into a state close to short fibers. The dewatering aid formed in the defibrating chamber 13 is pressure-fed by the high-speed jet airflow (compressed air) toward the communicating part 7 and supplied into the air diffuser pipe 9 connected to the communicating part 7. The desired dewatering aid can be obtained by appropriately changing the shape of the defibrating teeth and adjusting the degree of defibration depending on the implementation conditions.

[0029] The defibrator 5 used in this embodiment is a dry type defibrator that uses the airflow it generates to apply physical impact to the fibrous material supplied from the supply port 22, thereby defibrating the material and then pressurizing the resulting dewatering aid toward the communicating section 7, but the mechanism is not limited to that of this embodiment as long as it is capable of defibrating and pressurizing the fibrous material. In other embodiments, for example, after the fibrous material is defibrated using a defibrator that does not have an internal wind generating mechanism, the dewatering aid may be transported using a wind generating mechanism such as a blower connected to the fibrous material supply section 11. When the wind generating mechanism is installed externally, the compressed air obtained from the wind generating mechanism can also be used in the squeezing process, cake blowing process, etc.

[0030] FIG. 5 is an explanatory diagram showing the sludge mixing tank as seen from the front, and FIG. 6 is an explanatory diagram showing the sludge mixing tank as seen from the direction of the arrow shown in FIG. As shown in Figure 5, the sludge mixing tank 6 is connected to a sludge supply unit 15 at its lower end and to a sludge discharge unit 19 at its upper end. In this embodiment, the sludge is supplied from below, mixed and stirred in the tank, and then discharged from above.

[0031] The sludge mixing tank 6 has an air diffuser 9 extending into the tank so as to be located below the connection part 21 (sludge supply port) of the sludge supply part 15. The air diffuser 9 has a large number of jetting holes 20 formed therein and is connected to the communication part 7 so that the dewatering aid and compressed air pressure-fed from the communication part 7 can be jetted out of the jetting holes 20.

[0032] As shown in Fig. 6, the nozzle holes 20 are openings formed in the lower part of the air diffuser 9, and the dewatering aid and compressed air supplied into the air diffuser 9 are sprayed downward. Connection 21 and the nozzle holes 20 formed in the diffuser pipe 9 are directed downward, so that the sludge is not supplied toward the nozzle holes 20, and therefore the nozzle holes 20 are not blocked by the sludge supplied from the sludge supply unit 15. In this way, it is desirable to form the nozzle holes 20 of the diffuser pipe 9 at a position not facing the sludge supply unit 15.

[0033] The dewatering aid and compressed air are sprayed downward and then flow upward. At this time, the sludge supplied from above the air diffuser 9 is mixed and stirred with the dewatering aid while flowing upward by the compressed air supplied from below. After being uniformly mixed with the dewatering aid, the sludge becomes mixed sludge and is discharged from the sludge discharge section 19.

[0034] In this embodiment, in order to increase the fluidity of the sludge in the tank, mixture A partition plate 8 having a predetermined thickness is installed in the tank 6. This allows the sludge in the tank to be agitated by air lift using compressed air supplied from an air diffuser 9 installed below. mixtureThe tank 6 is installed so that it extends upward with predetermined gaps at its bottom and top, allowing sludge supplied from the sludge supply unit 15 to circulate around the partition plate 8 through the predetermined gaps at the bottom and top. In other words, by installing the partition plate 8 inside the tank, the sludge inside the tank can circulate vertically. As the supplied sludge flows around the partition plate 8 (in the flow direction of the arrow), the dehydration aid supplied from below is incorporated into the flowing sludge and mixed, producing mixed sludge with a uniformly mixed dehydration aid. In this embodiment, the supplied excess sludge is low in concentration and highly fluid, obtained by the OD method, and therefore can circulate efficiently around the partition plate 8 without accumulating at the bottom of the tank.

[0035] The inside of the sludge mixing tank 6 provided with the partition plate 8 is divided into areas with the partition plate 8 as a boundary. A and area B The area A is an area to which sludge is supplied from the sludge supply unit 15 and dewatering aid and compressed air are supplied from the communication unit 7. On the other hand, the area B is divided by the partition plate 8. B is the area where the mixed sludge produced by the air lift action occurring in the tank is discharged.

[0036] By configuring the tank so that the supplied sludge can be mixed and stirred together with the dewatering aid, the sludge does not remain at the bottom of the tank for a long time, preventing it from puttingrefying. At this time, the compressed air sprayed out together with the dewatering aid is compressed air generated by the rotation of the blower blades 17 inside the fiberizer 5, so there is no need to install a separate external wind generating mechanism such as a blower, and there is also no need to install a large mechanical stirring device.

[0037] The position, number, shape, etc. of the ejection holes 20 and the partition plate 8 are determined appropriately according to the design conditions. The connection position of the sludge supply part 15 and the sludge discharge part 19 is also not limited. The sludge supply part 15 may be connected to the top of the tank and the sludge discharge part 19 may be connected to the bottom of the tank, so that the sludge supplied from above is discharged from below. In order to prevent the ejection holes 20 from being blocked, the sludge supply part 15 may be connected to the bottom of the tank and the sludge discharge part 19 may be connected to the bottom of the tank. ConnectionThe air diffuser 9 with the nozzle 20 formed at the top may be disposed above the sludge mixing tank 6. The connection position of the communication part 7 is also appropriately set according to the shape of the sludge mixing tank 6. In addition, in order to perform air lift agitation efficiently, the compressed air supply pipe may be connected to the sludge mixture A separate connection to tank 6 may be made to increase the supply of compressed air.

[0038] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. [Industrial Applicability]

[0039] The dewatering aid adding device and dewatering aid adding method of the present invention use a defibrator to defibrate fibrous material that would otherwise be discarded, such as scraps generated during the manufacturing process of nonwoven fabrics, and use the defibrated material as a dewatering aid, thereby making effective use of fibrous material that would otherwise be discarded. By effectively utilizing waste generated in the area where this product is operated as a dewatering aid, it is possible to solve the waste disposal problems that the area faces. The dewatering aid defibrated by the defibrator is compressed and fed using compressed air generated by the blower blades inside the defibrator, eliminating the need for a separate energy source such as a wind generating mechanism, making this an environmentally friendly device. [Explanation of symbols]

[0040] 5. Fiberizer 6. Sludge mixing tank 7 Communication section 8 Divider 9 Air diffuser 12 Return Department 15 Sludge supply section 17 Blower blade 20 spouts

Claims

1. In a device that adds and mixes dewatering aids to sludge, A defibrator (5) that defibrates fibrous materials to form a dewatering aid; a communication section (7) connected to the defibrator (5) and for pressure-feeding the dewatering aid with compressed air; a sludge mixing tank (6) connected to a communication part (7) for mixing and stirring the sludge fluidized by the supplied compressed air together with a dewatering aid; Equipped with A dehydration aid adding device characterized by the above.

2. The defibrator (5) is a dry type defibrator, The other end is connected to a communication part (7) connected to the lower part of the sludge mixing tank (6), A blower blade (17) is provided to generate compressed air to be supplied to the communication part (7).

2. The dehydration aid adding device according to claim 1.

3. The sludge mixing tank (6) includes an aeration pipe (9) installed below and communicating with the communication part (7); A partition plate (8) extending upward with a predetermined gap provided at the bottom and top; a sludge supply unit (15) to which circulating sludge is supplied by compressed air supplied from an air diffuser pipe (9), The nozzle (20) of the air diffuser (9) is formed at a position not facing the sludge supply part (15).

3. The dehydration aid adding device according to claim 1 or 2.

4. A return section (12) for returning a part of the dewatering aid to the defibrator (5) is connected to the communication section (7).

4. The dehydration aid adding device according to claim 3.

5. In a dewatering aid addition method in which a dewatering aid is added and mixed with sludge, After defibrating the fiber material to form a dewatering aid, The dewatering aid is pressure-fed to the sludge mixing tank (6) using compressed air, The sludge is mixed and stirred with the dewatering aid by the compressed air supplied to the sludge mixing tank (6). A method for adding a dehydration aid.

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