JP3781755B2 - Sludge concentration device and sludge concentration method - Google Patents

Description

  The present invention relates to a sludge concentrating device and a concentration method for separating and concentrating sludge such as sewage sludge, and in particular, concentrating by separating the solid content in the sludge under reduced pressure and separating it from the liquid content (this specification). In addition, the present invention relates to a sludge concentration apparatus and its concentration method.

  2. Description of the Related Art Conventionally, in sludge treatment such as sewage sludge, techniques for preventing sludge decay and techniques for concentrating and dewatering for weight reduction have been actively developed.

  As a technology for concentrating this sludge, the sludge is put into a vacuum decompression vessel, the dissolved gas in the sludge is foamed under reduced pressure, and the foamed gas is allowed to float with the solid content of the sludge, and is separated into solid and liquid. A technique is known in which after the desorbed liquid separated into the lower part of the vacuum container is discharged, the floating separation sludge separated into the upper part of the vacuum container is discharged.

  In such a technology for concentrating sludge, as a method for creating a vacuum for the purpose of deaeration in sludge, a method of sucking the air layer side of the sealed tank with a vacuum pump and a liquid filled in the container There is a method of discharging with a pump.

  As a conventional technique for sucking the gas layer side with a vacuum pump, in order to completely remove fine bubbles in sludge using a vacuum container, let the gas in the container be exhausted with a vacuum pump to make the inside of the container a vacuum. (For example, refer to Patent Document 1).

Further, as a prior art for discharging the liquid in the container with a pump, in the invention previously filed by the present applicant, the liquid filled in the container is sucked out from the lower part with a suction pump to form a vacuum layer on the upper part of the container. By introducing sludge into this vacuum layer, carbon dioxide (CO ₂ ) and methane (CH ₄ ), etc., generated from anaerobic sludge are allowed to float above the sludge so as to be separated into a solid-liquid separation. There is one that is urged (see, for example, Patent Document 2).
JP 2000-271596 A (page 4, FIG. 1) Japanese Patent Laid-Open No. 10-156399 (page 4, FIG. 1-8)

  However, in the case of Patent Document 1, since the gas is discharged using a vacuum pump having a large power loss, the power loss of the apparatus increases. In addition, cooling water for cooling the vacuum pump may be necessary, and the apparatus is expensive.

  In the case of Patent Document 2, since liquid is discharged by a pump, cavitation occurs during suction depending on conditions, and measures such as piping vibration and pump wear are required. Moreover, it is necessary to take measures to discharge foreign matter such as hair in the sludge.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method capable of simplifying the process of evacuating a decompression vessel as much as possible.

  In order to achieve the above object, a sludge treatment apparatus of the present invention comprises a raw sludge storage tank for storing raw sludge, a sealable decompression vessel having a supply port for supplying raw sludge at the top and a discharge port at the bottom. A sludge supply pipe for supplying raw sludge to the decompression container; an exhaust pipe for discharging sludge or gas in the decompression container; and sludge for discharging sludge in the decompression container to the raw sludge storage tank from the outlet. A discharge pipe and a discharge pipe for discharging the liquid and solid components separated in a solid-liquid state from the discharge port are provided, and the sludge supply pipe, the exhaust pipe, the sludge discharge pipe, and the discharge pipe can be opened and closed. And the lower end of the sludge discharge pipe is sealed below the liquid level, and the reduced pressure vessel is disposed at a position higher than the height at which the atmospheric pressure acting on the sealed liquid level and the sludge pressure in the reduced pressure vessel are balanced. ing. The position higher than the height at which the sludge pressure in the decompression vessel and the atmospheric pressure are balanced is based on the so-called Torrichelli vacuum principle, and when the sludge in the decompression vessel is naturally dropped and discharged, Refers to the height at which is in a vacuum state. Thus, since the vacuum is created in the decompression container by utilizing the natural fall of sludge, the interior of the container can be easily evacuated without requiring the power for sucking gas or liquid.

  Further, in this sludge concentrating device, a desorption liquid tank for discharging the liquid component separated in the decompression container and a concentrated sludge storage tank for discharging the solid component separated in the decompression container are provided, and from the decompression container, A discharge pipe for discharging the liquid and solid components is constituted by a liquid discharge pipe and a solid discharge pipe, and the lower end of the liquid discharge pipe is sealed below the liquid level of the desorption liquid tank, and the lower end of the solid discharge pipe Is sealed under the liquid level of the concentrated sludge storage tank, and the lower ends of the sludge supply pipe, exhaust pipe, and sludge discharge pipe are sealed under the liquid level of the raw sludge storage tank. The solid component and the liquid component separated in step 1 can be efficiently separated into the respective tanks.

  Further, in these sludge concentrators, after filling the decompression container with raw sludge, the sludge in the decompression container is discharged into the raw sludge storage tank by natural fall from the discharge port, thereby evacuating the container. Forming and supplying the raw sludge to almost the middle position in the vacuum container, the dissolved gas in the sludge is foamed under reduced pressure, and the solid content of the sludge is entrained in the foamed gas and separated into solid and liquid. , After discharging the desorbed liquid separated in the lower part of the vacuum container to the desorbed liquid tank, the floating separated sludge separated in the upper part of the vacuum container is discharged to the concentrated sludge storage tank, and then the vacuum container Concentration treatment can be continuously performed by sequentially repeating the operation of supplying the raw sludge to almost the middle position and foaming the dissolved gas in the sludge under reduced pressure.

  On the other hand, in the sludge concentration method of the present invention, a sealable decompression vessel having a supply port for supplying raw sludge at the top and a discharge port at the bottom is discharged from the discharge port of the decompression vessel to the raw sludge storage tank. After the sludge discharge pipe is placed at a position higher than the height at which the atmospheric pressure acting on the liquid surface sealing the lower end of the sludge discharge pipe and the sludge pressure in the decompression container are balanced, the container is filled with the raw sludge, The sludge in the inside is discharged by spontaneous fall from the discharge port, a vacuum is formed in the container, and the dissolved gas in the sludge is foamed under reduced pressure by supplying the raw sludge into the vacuum container. It is made to concentrate by making it float with the solid content of sludge. Also in this method, since the vacuum is created in the decompression container by the natural fall of sludge using the so-called Tricherry vacuum, the interior of the container can be easily evacuated without requiring the power of sucking gas or liquid.

  In addition, a sealable decompression vessel having a supply port for supplying raw sludge at the top and a discharge port at the bottom is sealed, and the lower end of the sludge discharge pipe for discharging sludge from the discharge port of the decompression vessel to the raw sludge storage tank is sealed. Is disposed at a position higher than the height at which the atmospheric pressure acting on the liquid level and the sludge pressure in the decompression container are balanced, and after the interior of the decompression container is filled with raw sludge, the sludge in the container is discharged to the outlet A vacuum is formed in the container by discharging from the container by natural fall, and the raw sludge is supplied to almost the middle position in the container of the vacuum, and the dissolved gas in the sludge is foamed under reduced pressure, and the sludge solids into the foamed gas. The liquid is separated into solid and liquid by being floated together, and the desorbed liquid separated in the lower part of the vacuum container is discharged to the desorbed liquid tank, and then the levitated separation sludge separated in the upper part of the vacuum container is concentrated. Discharged into the sludge storage tank, and then If the raw sludge is supplied to almost the middle position in the empty container, and the operation of decompressing and foaming the dissolved gas in the sludge is repeated successively, the raw sludge is continuously concentrated. The inside of the container can be easily evacuated without requiring power by natural fall, and the raw sludge can be continuously concentrated with a volume at a substantially intermediate position of the decompression container.

  In the present invention, the inside of the tank can be evacuated without using a vacuum pump by the means as described above, so that power loss is small, equipment costs can be reduced, and sludge concentration can be easily handled.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a sludge concentrator showing an embodiment of the present invention.

  As shown in the figure, the sludge concentrating device 1 discharges a depressurization container 2 for solid-liquid separation of raw sludge, a raw sludge storage tank 3 for storing raw sludge O, and a desorbed liquid W separated in the depressurization container 2. A desorbing liquid tank 4 is provided, and a concentrated sludge storage tank 5 for discharging the concentrated sludge S separated in the decompression vessel 2 is provided. As the raw sludge stored in the raw sludge storage tank 3, the sludge produced by water treatment is stored.

  The decompression container 2 in this embodiment is a sealable container, and is formed in a conical shape in which the upper part is cylindrical and the lower part is conically narrowed. As will be described later, this conical portion is formed at an inclination angle at which the raw sludge O and the concentrated sludge S supplied into the decompression vessel 2 can fall by their own weight.

  Between the decompression container 2 and the raw sludge storage tank 3, a sludge supply pipe 6 for supplying the raw sludge from the raw sludge storage tank 3 to the supply port provided at the upper part of the decompression container 2, An exhaust pipe 7 for discharging gas such as gas or overflowed raw sludge to the raw sludge storage tank 3 is provided.

  At the lower end of the sludge supply pipe 6, there is provided a raw sludge pump 8 that draws the raw sludge from the raw sludge storage tank 3 and supplies it to the decompression vessel 2. The sludge supply pipe 6 and the exhaust pipe 7 are provided with on-off valves 9 and 10, respectively.

  Since the pump 8 supplies the raw sludge O to the decompression vessel 2 installed at a height of 10 meters or more from the raw sludge storage tank 3 as will be described later, the raw sludge O can be supplied to that height. Those having a discharge pressure are used.

  Furthermore, a sludge discharge pipe 11 that discharges sludge in the pressure reduction container 2 and a liquid discharge pipe 12 that discharges a liquid component separated into solid and liquid in the pressure reduction container 2 are provided in a discharge port provided in the lower part of the pressure reduction container 2. And a solid discharge pipe 13 that discharges the solid-liquid separated solid component. The sludge discharge pipe 11, the liquid discharge pipe 12 and the solid discharge pipe 13 are also provided with on-off valves 14, 15 and 16.

  Further, the lower ends of the sludge supply pipe 6, the exhaust pipe 7, and the sludge discharge pipe 11 are sealed below the liquid level of the raw sludge storage tank 3, and the lower end of the liquid discharge pipe 12 is the liquid in the desorption liquid tank 4. The solid discharge pipe 13 is sealed below the liquid surface of the concentrated sludge storage tank 5. In this way, the lower ends of all the tubes 6, 7, 11, 12, and 13 are sealed under the liquid surface, so that air does not enter the decompression vessel 2 from the ends of the tubes.

  And the said pressure reduction container 2 is arrange | positioned in the position higher than the height which the atmospheric pressure which acts on the liquid level of the raw sludge storage tank 3 which seals the lower end of the sludge discharge pipe 11, and the sludge pressure in the pressure reduction container 2 balance. Yes. That is, the height H shown in the figure is set to be higher than the height at which the sludge pressure in the decompression vessel 2 and the atmospheric pressure acting on the liquid surface of the raw sludge storage tank 3 are balanced. When the decompression vessel 2 and the sludge discharge pipe 11 communicate with each other, the sludge inside the decompression vessel 2 falls by its own weight due to the so-called Torricelli vacuum principle, and the inside of the decompression vessel 2 where the sludge falls A vacuum state is set.

  The height H from the liquid surface of the original sludge storage tank 3 of the decompression vessel 2 is about 10 meters as the height at which the water pressure and the atmospheric pressure are balanced in the Torrichelli vacuum, but the sludge discharge pipe It is preferable to secure a height of 13 meters or more in consideration of pressure loss and the like in the interior of 11.

  In this way, by utilizing the Trichelli vacuum principle, the raw sludge is discharged from the decompression vessel 2 placed at a predetermined height filled with the original sludge by natural fall, so that the liquid and the atmospheric pressure of the original sludge are discharged. Since the vacuum can be created in the upper part where the raw sludge has fallen to a position where the pressures of the two are balanced, the vacuum container 2 can be easily evacuated without using a vacuum pump.

  2 (a) and 2 (b) are block diagrams showing a process of concentrating sludge with the sludge concentrating device shown in FIG. 1, and FIGS. 3 (a) and 3 (b) are shown in FIG. FIG. 4A and FIG. 4B are configuration diagrams showing a concentration step subsequent to the sludge concentration step shown in FIG. A flow for concentrating the raw sludge by the sludge concentrator 1 will be described below based on these drawings.

  First, as shown in FIG. 2 (a), all the on-off valves 14, 15, 16 of the discharge pipes 11, 12, 13 provided at the lower part of the decompression vessel 2 are closed, and the pumping pump 8 removes the raw sludge storage tank 3. The raw sludge O is pumped into the decompression vessel 2 and the inside of the decompression vessel 2 is filled with the raw sludge O. At this time, the on-off valve 10 of the exhaust pipe 7 provided at the upper part of the decompression vessel 2 is opened to discharge the gas etc. in the decompression vessel 2 and supply the sludge in a state where the decompression vessel 2 is filled with the raw sludge O. The on-off valve 9 of the pipe 6 and the on-off valve 10 of the exhaust pipe 7 are closed, and the decompression vessel 2 is sealed.

  Next, as shown in FIG. 2 (b), only the on-off valve 14 of the sludge discharge pipe 11 returning to the raw sludge storage tank 3 provided at the lower part of the decompression vessel 2 is opened. Thereby, since the decompression container 2 is disposed at a position higher than the original sludge storage tank 3 by 10 meters or more, the original sludge O in the decompression container 2 naturally falls to the original sludge storage tank 3 and is discharged by its own weight. . At this time, the vacuum container 2 after the sludge is discharged is evacuated from the principle of Trichelli's vacuum.

  That is, since a height difference of 10 meters or more is provided between the lower end of the decompression container 2 and the liquid level of the raw sludge storage tank 3, the raw sludge O in the decompression container 2 is naturally dropped by its own weight, and the original sludge storage tank Returning to 3, the vacuum is sequentially applied from above in the decompression vessel 2. Thus, by using the Trichelle vacuum, the inside of the decompression vessel 2 is evacuated without requiring suction power. In this way, almost the entire amount of the raw sludge O in the decompression vessel 2 is discharged to the raw sludge storage tank 3 so that the inside of the decompression vessel 2 is in a vacuum state.

  Thereafter, as shown in FIG. 3 (a), the on / off valve 14 of the sludge discharge pipe 11 is closed, the on / off valve 9 of the sludge supply pipe 6 is opened, and the raw sludge pumping pump 8 creates a vacuum from the raw sludge storage tank 3. The raw sludge O is again supplied into the reduced pressure vessel 2. The amount of the raw sludge O supplied again into the vacuum container 2 that has been evacuated is about half of the capacity of the vacuum container 2, and the on-off valve 9 of the sludge supply pipe 6 is closed after the supply.

In the raw sludge O supplied into the vacuum vessel 2 in a vacuum state in this way, dissolved gases such as carbon dioxide (CO ₂ ) and methane (CH ₄ ) in the sludge are foamed, and the foamed gas Since the foam adheres to the solid content in the raw sludge and entrains the solid content and floats upward, it is possible to separate the upper portion into the solid portion and the lower portion into the liquid portion in the vacuum vessel 2.

  Thereby, the raw sludge in the decompression vessel 2 can be solid-liquid separated and concentrated or degassed, the desorbed liquid W is accumulated in the lower part of the container, and the concentrated sludge S is accumulated in the upper part of the container. Thus, solid-liquid separation is performed by supplying the raw sludge O into the vacuum container 2 in a vacuum state and foaming the dissolved gas under reduced pressure.

  Then, as shown in FIG. 3 (b), the desorbed liquid W that has been solid-liquid separated and accumulated in the lower part of the decompression vessel 2 is opened to the desorbed liquid tank 4 by opening the on-off valve 15 of the liquid discharge pipe 12. And discharged. The operation of opening the on-off valve 15 and discharging the desorbed liquid W is controlled by a sensor (not shown) provided in the decompression container 2, and the on-off valve 15 is closed when the discharge of the desorbed liquid W from the decompression container 2 is completed. It is done. Also at this time, since the difference in level between the liquid level of the detachment liquid tank 4 and the decompression container 2 is 10 meters or more, the detachment liquid W can be discharged into the detachment liquid tank 4 by natural fall.

  Also, as shown in FIG. 4 (a), the concentrated sludge S collected on the top of the desorbed liquid in the decompression vessel 2 is discharged into the concentrated sludge storage tank 5 by opening the on-off valve 16 of the solid discharge pipe 13. The The concentrated sludge S can be discharged to the concentrated sludge storage tank 5 by natural fall because the difference in level between the liquid level of the concentrated sludge storage tank 5 and the decompression vessel 2 is 10 meters or more.

  Thereafter, as shown in FIG. 4 (b), the operation proceeds to the above-described operation of FIG. 3 (a), and the raw sludge O having about half the capacity is supplied into the vacuum container 2 in a vacuum state, and the foam is decompressed and foamed. As shown in FIGS. 3 (b) and 4 (a), solid-liquid separation is repeated, and the operation of discharging the separated desorbed liquid and concentrated sludge is repeated.

  In this way, the concentration of sludge by subjecting the raw sludge O to reduced pressure foaming and solid-liquid separation is automatically controlled by controlling the pump 8 and the on-off valves 9, 10, 14, 15, 16 by a control device (not shown). It is also possible to perform a continuous concentration operation.

  As described above, in this sludge concentrating device 1, the arrangement itself of the decompression vessel 2 is increased so as to use the Trichelli vacuum principle, and the raw sludge (liquid) is discharged out of the decompression vessel 2 only by its own weight. Since the inside of the decompression vessel 2 is in a vacuum state, a pump for evacuating the inside of the vessel is unnecessary, and the facilities are reduced, and sludge excellent in terms of initial cost, running cost, ease of handling, etc. The concentrating device 1 can be configured.

  Note that the desorption liquid tank 4 in the above embodiment only needs to be configured so that the lower end of the liquid discharge pipe 12 can be sealed below the liquid level, and is configured to always flow even if the desorption liquid is stored. There may be, and it is not limited to the said embodiment.

  In the above embodiment, the raw sludge O is supplied into the decompression container 2 by the pump 8. However, a raw sludge storage tank (not shown) is provided at a higher position than the decompression container 2, and the head of the original sludge storage tank is provided. You may comprise so that the raw sludge O may be supplied in a pressure reduction container with a pressure.

  Furthermore, the above-described embodiment shows an example, and various modifications can be made without departing from the gist of the present invention, and the present invention is not limited to the above-described embodiment.

  The sludge concentrating apparatus according to the present invention does not use a pump for evacuating the inside of the decompression vessel, and is therefore useful when concentrating raw sludge for which a special pump must be used. It is also useful for degassing raw sludge.

It is a block diagram of the sludge concentration apparatus which shows one Embodiment of this invention. (a), (b) is a block diagram which shows the process of concentrating sludge with the sludge concentration apparatus shown in FIG. (a), (b) is a block diagram which shows the concentration process following the sludge concentration process shown in FIG. (a), (b) is a block diagram which shows the concentration process following the sludge concentration process shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sludge concentrator 2 ... Depressurization container 3 ... Original sludge storage tank 4 ... Desorption liquid tank 5 ... Concentrated sludge storage tank 6 ... Sludge supply pipe 7 ... Exhaust pipe 8 ... Pump 9,10 ... On-off valve 11 ... Sludge discharge pipe DESCRIPTION OF SYMBOLS 12 ... Liquid discharge pipe 13 ... Solid discharge pipes 14, 15, 16 ... Open-close valve O ... Raw sludge S ... Concentrated sludge W ... Desorption liquid H ... Height

Claims (5)

  A raw sludge storage tank for storing raw sludge, a sealable decompression vessel having a supply port for supplying raw sludge at the top and a discharge port at the bottom, a sludge supply pipe for supplying raw sludge to the decompression vessel, An exhaust pipe for discharging sludge or gas in the decompression container; a sludge discharge pipe for discharging the sludge in the decompression container to the raw sludge storage tank from the outlet; and a liquid component separated into solid and liquid in the decompression container; And a sludge supply pipe, an exhaust pipe, a sludge discharge pipe, and a discharge pipe that can be opened and closed, and the lower end of the sludge discharge pipe is sealed below the liquid level. And the sludge concentration apparatus which has arrange | positioned the said pressure reduction container in the position higher than the height which the atmospheric pressure which acts on this sealed liquid level and the sludge pressure in a pressure reduction container balance. In the sludge concentration apparatus of Claim 1,
A desorption liquid tank for discharging the liquid component separated in the vacuum container and a concentrated sludge storage tank for discharging the solid content separated in the vacuum container are provided, and the liquid and solid contents are discharged from the vacuum container. The discharge pipe is composed of a liquid discharge pipe and a solid discharge pipe, the lower end of the liquid discharge pipe is sealed below the liquid level of the desorption liquid tank, and the lower end of the solid discharge pipe is the liquid of the concentrated sludge storage tank. A sludge concentrating device that seals below the surface and seals the lower ends of the sludge supply pipe, exhaust pipe, and sludge discharge pipe below the liquid level of the raw sludge storage tank. In the sludge concentration apparatus according to claim 1 or 2,
After filling the decompression container with raw sludge, the sludge in the decompression container is discharged into the raw sludge storage tank by natural fall from the discharge port to form a vacuum in the container, By supplying the raw sludge to almost the middle position, the dissolved gas in the sludge was foamed under reduced pressure, and the solid was separated from the foamed gas with the solid content of the sludge, and separated into the lower part of the decompression vessel. After discharging the desorbed liquid, the floating separation sludge separated at the top of the vacuum container is discharged, and then the raw sludge is supplied to almost the middle position in the vacuum container to foam the dissolved gas in the sludge under reduced pressure. A sludge concentrator equipped with a control device that continuously concentrates the raw sludge by repeating the operation.   Liquid that seals the lower end of a sludge discharge pipe that discharges sludge from the discharge port of the decompression vessel to the raw sludge storage tank, with a supply port for supplying raw sludge at the top and a discharge port at the bottom. The atmospheric pressure acting on the surface and the sludge pressure in the decompression vessel are arranged at a position higher than the balance, and after filling the decompression vessel with raw sludge, the sludge in the vessel is naturally discharged from the discharge port. A vacuum is formed in the container by discharging by dropping, and the raw sludge is supplied into the vacuum container, and the dissolved gas in the sludge is foamed under reduced pressure, and the foamed gas is allowed to accompany the solid content of the sludge. A method for concentrating sludge by concentrating. Liquid that seals the lower end of a sludge discharge pipe that discharges sludge from the discharge port of the decompression vessel to the raw sludge storage tank, with a supply port for supplying raw sludge at the top and a discharge port at the bottom. The atmospheric pressure acting on the surface and the sludge pressure in the decompression vessel are arranged at a position higher than the balance, and after filling the decompression vessel with raw sludge, the sludge in the vessel is naturally discharged from the discharge port. By discharging by dropping, a vacuum is formed in the container, and by supplying the raw sludge to almost the middle position in the vacuum container, the dissolved gas in the sludge is foamed under reduced pressure, and the solid content of the sludge is added to the foamed gas. After separating the solid and liquid by floating together and discharging the separated liquid separated at the lower part of the decompression container, the separated separation sludge separated at the upper part of the decompression container is discharged, and then inside the vacuum container Provide raw sludge to almost the middle position Sludge concentration method of sequentially repeated continuously concentrated raw sludge the operation of the dissolved gas in the sludge under reduced pressure foaming by.

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