JP3781756B2 - Continuous solid-liquid separation method and apparatus by vacuum degassing treatment - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a method and apparatus for performing solid-liquid separation by subjecting sludge such as sewage sludge under reduced pressure, and in particular, a solid-liquid separation method and apparatus capable of performing solid-liquid separation while continuously supplying raw sludge. About.

  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.

  For example, as a technique for separating and recovering solids (solid content) from raw sludge containing low-concentration solids, there are methods such as gravity sedimentation, centrifugal concentration, pressurized flotation, and atmospheric flotation. However, these methods have advantages and disadvantages in the size, processing speed, processing energy, and complexity of the device.

  One such sludge solid-liquid separation method is vacuum degassing. In this vacuum degassing treatment, raw sludge is put into a vacuum container close to a vacuum, dissolved gas in the raw sludge is foamed under reduced pressure, and the foamed gas is allowed to float with the solid content of the sludge. This is a sludge solid-liquid separation technology that separates the solids at the top and the liquids at the bottom. And after separating the liquid (desorbed liquid) in the lower part of the solid (concentrated sludge) in the upper part of the container in this way, after draining the desorbed liquid from the lower part of the container, the concentrated sludge accumulated in the upper part is removed. It is discharging.

As a prior art related to this type of vacuum degassing treatment, in the invention previously filed by the present applicant, the liquid filled in the container is sucked out from the lower part by a suction pump to form a vacuum layer on the upper part of the container. By introducing sludge into the sludge, the dissolved gas such as carbon dioxide (CO ₂ ) and methane (CH ₄ ) generated from the anaerobic sludge is caused to rise to the top by entraining the sludge to promote solid-liquid separation. (For example, refer to Patent Document 1).
Japanese Patent Laid-Open No. 10-156399 (page 4, FIG. 1-8)

  However, in Patent Document 1, since the concentrated sludge separated upward is discharged after discharging the desorbed liquid separated into solid and liquid, the supply of raw sludge to the decompression vessel must be stopped during that time. The operation of solid-liquid separation must also be stopped. That is, the liquid supply into the decompression container is intermittent. In addition, since several tens of minutes of standing time is required, the intermittent time for stopping supply (liquid supply) and discharge (drainage) to the container becomes long, and continuous operation cannot be performed. For this reason, it is necessary to provide a raw sludge storage tank for storing the raw sludge so that the supply of liquid to the decompression vessel can be stopped for continuously generated raw sludge.

  Furthermore, the processing capacity in the case of solid-liquid separation by degassing the raw sludge supplied into the decompression vessel in this way is limited to the capacity of the decompression vessel, and the solid-liquid separation is intermittently performed in the decompression vessel and discharged. It depends on the amount. For this reason, many decompression containers are required to increase the processing capacity, resulting in a problem of equipment space and an increase in equipment costs.

  In the conventional method, the separated desorbed liquid and the concentrated sludge are discharged from the lower part of the container under atmospheric pressure. Therefore, in order to reduce the pressure in the container again, a solid or dissolved gas different from the original sludge is used. Prepare a liquid that does not contain, and after filling the vacuum tank with this liquid, there is a case where the pressure reduction operation in the vacuum container may be performed by draining the liquid, and the raw sludge cannot be treated to reduce the pressure in the vacuum container Special process is required.

  Furthermore, in order to discharge the solid content (concentrated sludge) collected in the decompression vessel in this way, a special pump such as a single screw pump or a piston pump is required, and bubbles of foaming gas are attached. When sludge is discharged, cavitation is likely to occur in the pump, and countermeasures are also required.

  In addition, there is a desire to further improve the sludge treatment efficiency by more efficiently performing the solid-liquid separation of such raw sludge.

  Therefore, in order to solve the above-described problem, the continuous solid-liquid separation method using the vacuum degassing process according to the present invention supplies the raw sludge into a vacuum container whose pressure is reduced to an internal pressure capable of vacuum degassing. Then, the dissolved gas in the supplied raw sludge is foamed under reduced pressure, the solid content of the sludge is entrained in the foamed gas and floated, and the solid content is collected at the upper part of the decompression vessel and separated into solid and liquid. Operation to discharge the solids and foam gas collected in the upper part from the upper part of the decompression container, operation to discharge the desorbed liquid collected in the lower part of the decompression container, and supply raw sludge into the decompression container The solid content and the liquid content separated in the vacuum vessel are controlled by controlling the discharge rate and the supply rate and performing solid-liquid separation by continuously degassing the raw sludge in the vacuum vessel. Is discharged from the top and bottom of the decompression vessel to stop the solid-liquid separation of the raw sludge. It can be performed continuously without.

  Further, in the continuous solid-liquid separation method by the vacuum degassing process, the desorbed liquid discharged from the lower part of the vacuum container is opened below the liquid level of the drainage tank having a height difference of 10 meters or more downward from the vacuum container. If the discharge liquid in the decompression container is discharged from the decompression container by its own weight, the desorption liquid can be discharged from the decompression container without requiring a drain pump. Can do.

  Further, in these continuous solid-liquid separation methods by vacuum degassing, the raw sludge is supplied from the tangential direction of the wall of the vacuum vessel to form a swirl flow in the vacuum vessel. For example, it is possible to promote the decompression foaming in the decompression vessel and prevent the sludge from adhering.

  Further, in these continuous solid-liquid separation methods by vacuum degassing treatment, by extending the discharge timing of the solid collected at the upper part of the vacuum vessel until the pressure in the vacuum vessel rises to a predetermined pressure, the solids If the layer is thickened to increase the concentration effect by consolidation, the sludge that has been separated into solid and liquid is concentrated in the vacuum vessel until the pressure inside the vacuum vessel rises above the pressure at which solid-liquid separation can be performed satisfactorily. The function to do can be given.

  On the other hand, the continuous solid-liquid separation device by vacuum degassing treatment according to the present invention foams the dissolved gas in the raw sludge under reduced pressure, and causes the foamed gas to float along with the solid content of the sludge. A vacuum container for collecting and separating the solid and liquid, an outlet for discharging the foaming gas and the solids at the upper part of the vacuum container, and an outlet for discharging the desorbed liquid at the lower part of the vacuum container; A supply port for supplying raw sludge is provided at the side of the decompression vessel, the supply rate of the raw sludge supplied from the supply port into the decompression vessel, and the discharge rate of the solids and desorbed liquid discharged from the discharge port In order to perform solid-liquid separation, the raw sludge supplied into the vacuum vessel is continuously degassed and degassed.

  Further, in the continuous solid-liquid separation device by this vacuum degassing treatment, a liquid discharge pipe is provided at the discharge port of the pressure reduction container, and the lower end of the liquid discharge pipe has a height difference of 10 meters or more downward from the pressure reduction container. By opening the tank below the liquid level so that the desorbed liquid in the decompression vessel is discharged by its own weight, the desorbed liquid can be discharged without requiring a drainage pump.

  Furthermore, in these continuous solid-liquid separation devices using vacuum degassing treatment, the supply port is arranged in the tangential direction of the wall of the vacuum vessel, and a swirling flow is generated in the vacuum vessel by the raw sludge supplied from the supply port. If comprised in this, promotion of the decompression foaming in a decompression container and adhesion of sludge can be prevented.

  Further, in these continuous solid-liquid separation devices using vacuum degassing, a sensor for detecting the internal pressure is provided in the vacuum container, and the pressure is reduced until the sensor detects that the pressure in the vacuum container has increased to a predetermined pressure. If the concentration of solids collected at the top of the container is increased to increase the concentration effect due to compaction, the solids (concentrated sludge) until the pressure inside the vacuum container rises above the pressure at which solid-liquid separation can be satisfactorily achieved. The concentration of can be further increased.

  Since the present invention can continuously perform solid-liquid separation while continuously supplying raw sludge into the decompression vessel by means as described above, it is possible to efficiently perform solid-liquid separation of the raw sludge. It becomes.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a continuous solid-liquid separator according to a first embodiment of the present invention. In addition, although this embodiment demonstrates the structure which provided the storage tank which stores raw sludge, this storage tank is not necessarily required, and when the processing amount which carries out solid-liquid separation with a decompression vessel is small so that it may mention later. What is necessary is just to provide.

  As shown in the figure, the continuous solid-liquid separation device 1 in the first embodiment uses raw sludge storage tank 2 for storing raw sludge O, and dissolved gas in the raw sludge supplied from this raw sludge storage tank 2. A decompression vessel 3 is provided in which the foamed gas is floated and the foamed gas entrains the solid content of sludge and floats to collect the solid content and separate into solid and liquid.

  The raw sludge storage tank 2 is provided with an upper level meter L1 and a lower level meter L2 for detecting the sludge level in the storage tank 2.

  The supply pipe 4 for supplying the raw sludge O from the raw sludge storage tank 2 to the decompression vessel 3 is provided with an on-off valve M1 for adjusting the supply amount of the raw sludge. The opening / closing amount of the on-off valve M1 is controlled by signals from level meters L1, L2 provided in the raw sludge storage tank 2.

  A supply port 5 to which the supply pipe 4 is connected is provided at the upper side of the side wall of the decompression vessel 3, a discharge port 6 for discharging foaming gas and concentrated sludge is provided at the upper end, and a removal port is provided at the lower end. A discharge port 7 for discharging the liquid separation W is provided. A discharge pipe 8 connected to a discharge port 6 provided at the upper end is branched into a sludge discharge pipe 9 and an exhaust pipe 10, and the sludge discharge pipe 9 has an on-off valve for adjusting the discharge amount of concentrated sludge. M3 is provided, and the exhaust pipe 10 is provided with an on-off valve M2 for adjusting the discharge amount of the foaming gas. The discharge pipe 11 connected to the discharge port 7 provided at the lower end is provided with an on-off valve 12 for adjusting the discharge amount of the desorbed liquid.

  Further, a pressure gauge PIC for detecting the pressure in the decompression container 3 is provided on the upper part of the decompression container 3, and an upper level meter L3 and a lower level gauge L4 for detecting the amount of sludge in the decompression container 3 are provided on the side parts. And are provided. Opening / closing of the on-off valves M3, M2, 12 is controlled by signals from the pressure gauge PIC and the level gauges L3, L4. The pressure gauge PIC is a detection sensor that determines that the degree of vacuum in the decompression vessel 3 has decreased when the pressure in the decompression vessel 3 rises to a predetermined pressure (for example, a degree of vacuum of −70 KPa or less). The dotted line shown in the figure is a control line, and control of the on-off valves M3, M2, and 12 by signals from this control line is performed by a control device (not shown).

  In addition, as shown by a two-dot chain line in the drawing, the lower end of the discharge pipe 11 provided at the lower end of the decompression vessel 3 is provided with a drainage tank 13 provided with a height difference of 10 meters or more with the decompression vessel 3. By sealing under the liquid level WL, the desorbed liquid discharged downward from the decompression vessel 3 can be discharged by its own weight according to the Trichelli vacuum principle. That is, the desorbed liquid in the vacuum container 3 in a vacuum state is lowered to a height that balances with the atmospheric pressure acting on the liquid level WL of the drainage tank 13 that seals the lower end of the discharge pipe 11, so that the height difference is 10 meters or more. The desorbed liquid is discharged from the decompression vessel 3 to the lower drainage tank 13 by its own weight. In this way, it is possible to discharge the desorbed liquid without requiring power from a pump or the like.

  2 (a) to 2 (d) are schematic diagrams showing the flow of a method for performing continuous solid-liquid separation by performing a vacuum degassing treatment with the continuous solid-liquid separation device shown in FIG. A continuous solid-liquid separation method by the continuous solid-liquid separation device 1 will be described below based on these drawings. The arrows shown in the figure indicate a state with a flow.

  First, as shown in FIG. 2 (a), the on-off valve 12 provided on the discharge pipe 11 of the decompression vessel 3 is closed, and the on-off valves M2 and M3 provided on the discharge pipes 9 and 10 are opened. The raw sludge O is supplied from the pipe 4 into the decompression container 3, and the gas in the decompression container 3 is exhausted from the top of the container. Then, after exhausting all the gas in the decompression vessel 3 and filling the decompression vessel 3 with the raw sludge O, the on-off valve M2 of the exhaust pipe 10 is closed. This is the initial filling process.

  Next, as shown in FIG. 2 (b), the internal raw sludge O is discharged by opening the on-off valve 12 provided in the discharge pipe 11 of the decompression vessel 3 in this state. At this time, as described above, by sealing the lower end of the discharge pipe 11 of the decompression vessel 3 under the liquid level WL of the drainage tank 13 having a height difference of 10 meters or more (FIG. 1), the sealed decompression vessel 3 is sealed. A vacuum is formed in the decompression vessel 3 after the raw sludge O is discharged by its own weight. In addition, when the decompression container 3 cannot be arrange | positioned in the high place which has such an elevation difference, what is necessary is just to form a vacuum by discharging | emitting the raw sludge O in the decompression container 3 with a pump.

  When the vacuum container 3 is formed in a vacuum in this way, the raw sludge O containing solids is decompressed to near vacuum, so that the dissolved gas in the liquid is foamed and degassed, and the foamed gas is sludged. The solid content is accompanied and floated and separated. Thereby, the solid content in the raw sludge is floated and separated along with the foamed gas to become the concentrated sludge S.

  Moreover, since the raw sludge O is supplied while discharging the desorbed liquid W separated in this way from the lower part of the decompression vessel 3, the raw sludge O is always supplied into the decompression vessel 3 in a vacuum. At the same time, the dissolved gas in the raw sludge O is foamed under reduced pressure, the solid content is lifted up, and the liquid is separated into the lower portion. This is the process of drainage vacuum concentration.

  In addition, as shown in FIG. 2 (c), while supplying the desorbed liquid W separated in a solid-liquid manner in the reduced-pressure vessel 3 in this way and gathered at the lower portion from the discharge pipe 11 at the lower end by a predetermined amount, From 4, raw sludge O is supplied into the vacuum container 3, and the supplied raw sludge O is continuously solid-liquid separated in the vacuum container 3. At this time, when the level of the raw sludge O in the decompression vessel 3 reaches the upper level meter L3, the opening of the on-off valve 12 is increased, and a relatively large amount of the desorbed liquid W in the decompression vessel 3 is discharged. When the level of the raw sludge O reaches the lower level meter L4, the opening degree of the on-off valve 12 is reduced and a relatively small amount of the desorbed liquid W in the decompression vessel 3 is discharged. When the level of the raw sludge O changes between the level meter L3 and the level meter L4, the raw sludge O supplied from the supply pipe 4 with the opening degree of the on-off valve 12 reduced is reduced. 3 is controlled so as to be accumulated in 3. Therefore, the layer of concentrated sludge S (solid content) separated into solid and liquid gradually increases in the upper part of the decompression vessel 3, and the concentration of separated solids can be increased by the consolidation effect. This is the process of floating thick condensation.

  When the solid-liquid separation is performed in the reduced pressure vessel 3 in this way and the concentrated sludge S is collected on the upper part, the pressure in the reduced pressure vessel 3 is increased by the gas in the concentrated sludge S, and the pressure vessel PIC When it is detected that the pressure has increased to a predetermined pressure (for example, a degree of vacuum of −70 KPa or less), it is determined that the degree of vacuum in the decompression container 3 has decreased, and the gas in the decompression container 3 and the concentrated sludge S are discharged. .

  As shown in FIG. 2 (d), these discharges are performed by opening the open / close valve M 2 of the exhaust pipe 10 and the open / close valve M 3 of the sludge discharge pipe 9 provided at the top of the decompression vessel 3. The valve 12 is closed. Thereby, the foamed gas accumulated in the upper part of the decompression vessel 3 is discharged from the exhaust pipe 10, and the concentrated sludge S (solid content) collected by floating and separating on the upper part of the decompression vessel 3 is supplied from the supply pipe 4. O is discharged from the sludge discharge pipe 9 by O. The force for pushing the concentrated sludge S (solid content) from the decompression vessel 3 as described above includes the head pressure of the raw sludge storage tank 2 as shown in FIG. Obtained by. Further, at this time, the opening degree of the on-off valve 12 may be slightly opened rather than fully closed, and the concentrated sludge S may be discharged while discharging the desorbed liquid W. This is the process of floating sludge discharge.

  Then, after the concentrated sludge S (solid content) floated and separated in this way is discharged from the top of the decompression vessel 3, the on-off valves M2 and M3 are closed and the desorbed liquid W discharged from the discharge pipe 11 of the decompression vessel 3 is discharged. If the liquid level of the decompression vessel 3 is lowered by increasing the speed, the inside of the decompression vessel 3 can be depressurized. Therefore, the raw sludge O can be continuously added without changing the supply rate of the original sludge O into the decompression vessel 3. Can be processed.

  After the concentrated sludge S solid-liquid separated in the decompression vessel 3 in this way is discharged, the on-off valve M2 of the exhaust pipe 10 and the on-off valve M3 of the sludge discharge pipe 9 are closed and the on-off valve 12 of the discharge pipe 11 is closed. Is released. As a result, the raw sludge O newly supplied into the decompression vessel 3 is foamed under reduced pressure, and solid-liquid separation is performed in which the solid component is floated upward by the gas. Thereafter, as described above, solid-liquid separation is performed while discharging the desorbed liquid W, and the operation of discharging the concentrated sludge S when it reaches a predetermined amount is repeated.

  Further, when solid-liquid separation is performed in the reduced pressure vessel 3 in this way, the supply rate of the raw sludge O is not changed, and if the discharge rate from the lower portion of the reduced pressure vessel 3 is made slower than the supply rate, the reduced pressure vessel The liquid level in 3 is raised, and the concentrated sludge S (solid content) floated and separated from the foaming gas in the container can be discharged from the top of the decompression container 3.

  In this way, while the raw sludge O is constantly supplied into the decompression vessel 3, the solid-liquid separation process of the raw sludge O is continuously performed while switching between the discharge of the separated liquid W and the discharge of the concentrated sludge S. Made.

  In addition, as a method of depressurizing the inside of the decompression vessel 3, a liquid containing solids is supplied into the decompression vessel 3, and the gas and the solid matter floating and separated in the decompression vessel 3 are discharged from the top of the vessel. Alternatively, the inside of the container may be decompressed by draining the liquid in the decompression container 3 from the bottom of the container after closing the discharge port at the top of the container.

  As described above, the supply of the raw sludge O from the supply pipe 4 and the discharge of the desorbed liquid W from the discharge pipe 11 and the discharge of the concentrated sludge S from the discharge pipe 8 are performed on the on-off valves M2 and M3. , 12 can be opened and closed by the time control and the time control, so that the raw sludge O can be continuously solid-liquid separated.

  That is, in the process of discharging the desorbed liquid W and the concentrated sludge O separated into solid and liquid, it can be continuously performed without stopping the solid-liquid separation process in the decompression vessel 3, so Separation can be performed efficiently.

  As described above, in this embodiment, since usually only the desorbed liquid is discharged from the lower part of the decompression vessel 3, a general spiral pump for transporting the liquid is provided in the discharge pipe 11, and this pump is used. Discharged liquid discharge from the decompression container 3 and concentrated sludge S (solid content) from the upper part of the decompression container 3 by controlling the discharge amount of the pump may be performed. In this case, even when the concentrated sludge S is discharged from the upper part of the decompression vessel 3, the pump provided in the discharge pipe 11 is rotated at the minimum number of rotations, thereby reducing the number of times the pump is driven / stopped and the pump life. Can be improved.

  3 (a) and 3 (b) are configuration diagrams showing a continuous solid-liquid separation device according to a second embodiment of the present invention. In the second embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted. In addition, since the operation in the second embodiment is the same as that in FIGS. 2A to 2D described above, detailed description of the same operation as that in FIGS. 2A to 2D described above is omitted.

  As shown in FIG. 3 (b), in this second embodiment, the supply port 5 provided in the decompression vessel 3 is provided in the tangential direction of the wall eccentric from the center. By supplying the raw sludge O into the inside, the raw sludge O supplied into the decompression vessel 3 is configured to generate a swirling flow in the decompression vessel 3.

  By generating a swirling flow in the decompression vessel 3 as described above, the solid-liquid separation is promoted by the bubble adhering effect of the swirling flow, and the solid component (concentrated sludge S) that floats adheres to the wall surface of the decompression vessel 3. The concentrated sludge S can be easily discharged from the top of the decompression vessel 3. When the swirl flow is generated in this way, the raw sludge O to be supplied is separated and supplied so as not to stir the sludge collected at the upper part.

  Further, as shown in FIGS. 3A and 3B, in this embodiment, a flocculant supply unit 14 is provided in the supply pipe 4 at a position close to the supply port 5. The flocculant supply unit 14 is configured to add a predetermined amount of the flocculant 15 into the raw sludge O supplied from the supply pipe 4. Thus, by adding the flocculant 15 to the raw sludge O and supplying it into the decompression vessel 3, the agglomeration action of the solid part can be enhanced and the floating separation of the solid part can be promoted.

  Moreover, by continuously adding this flocculant, in addition to the mixing and stirring effect, the degassing and foaming action of the dissolved gas in the decompression vessel 3 is caused by the potential difference on the solid surface (liquid PH due to foaming of carbon dioxide gas or the like). And the surface tension effect due to foaming of bubbles on the surface of the solid increases, the effect of agglomeration of the solids increases, and the floating separation property of the solid can be improved. It is only necessary to determine whether or not to add this flocculant according to the outlet target concentration of the decompression vessel 3, and the conditions such as the addition ratio.

  Even with the continuous solid-liquid separation device 16 of the second embodiment configured as described above, the raw sludge O can be continuously solid-liquid separated in the same process as in FIGS. 2 (b) to (d). it can.

  That is, as shown in FIG. 2 (b), when the raw sludge O is supplied while discharging the desorbed liquid W from the vacuum container 3 in a vacuum state, the dissolved gas in the supplied raw sludge O is decompressed and foamed. Thus, solid-liquid separation is achieved. And according to this 2nd Embodiment, the solid-liquid separation promotion and the improvement of the floating separation speed of the concentrated sludge S can be aimed at by the flocculant added to the raw sludge O and the swirl flow. Then, when the upper pressure of the decompression vessel 3 is increased, the concentrated sludge S is discharged. However, according to the second embodiment, the swirl flow is generated by the raw sludge O. The prevented carry-out speed can be improved. Since others are the same as those of the first embodiment described above, detailed description thereof is omitted.

  FIG. 4 is a block diagram showing a continuous solid-liquid separation device according to the third embodiment of the present invention. This 3rd Embodiment is embodiment which comprised the sludge storage tank installed in the ground etc. as the decompression container 3 mentioned above. In addition, the same code | symbol is attached | subjected to the structure same as 1st Embodiment mentioned above, and detailed description is abbreviate | omitted.

  As shown in the figure, a decompression container 3 (sludge storage tank) having a strength that can withstand even when the inside is in a vacuum state is provided, and supply of raw sludge O to the lower portion of the left side wall of the decompression container 3 shown in the figure. A discharge port 7 for the desorbed liquid W is provided at the lower right side, a discharge port 6 for the concentrated sludge S is provided at the upper right side, and a foam gas exhaust port 18 is provided at the top. Yes. An open / close valve 19 is opened when gas is discharged from the exhaust pipe 20 provided at the exhaust port 18.

  The supply pipe 4 connected to the supply port 5 is provided with a pump 21 for supplying raw sludge O, the discharge pipe 11 connected to the discharge port 7 is provided with a drainage pump 22, and the discharge port 6 The sludge discharge pipe 9 connected to the is provided with a sludge discharge pump 23.

  According to the continuous solid-liquid separation device 17 of the third embodiment configured as described above, first, the supply port 5 is opened by the pump 21 while opening the on-off valve 19 at the top of the decompression vessel 3 and venting the gas from the exhaust port 18. Then, the raw sludge O is supplied into the decompression vessel 3, and after the interior of the decompression vessel 3 is filled with the raw sludge O, the decompression vessel 3 is sealed.

  Then, the desorbed liquid W collected in the lower part of the decompression vessel 3 is discharged from the lower part by the drainage pump 22. When the desorbed liquid W is extracted from the lower part of the decompression container 3 filled with the raw sludge O in this way, a vacuum is formed on the upper part of the decompression container 3 by the amount of the removal.

  When the inside of the decompression vessel 3 is evacuated in this manner, the dissolved gas contained in the raw sludge O in the storage tank is decompressed and foamed under vacuum, and the foamed gas adheres to the solid content and the solid content is decompressed. The solid-liquid separation is achieved in the decompression vessel 3 by floating on the top of 3. Thereby, the concentrated sludge S (solid content) is collected at the upper part of the decompression vessel 3, and the desorbed liquid W is collected at the lower part.

  After the raw sludge O is solid-liquid separated in this way, the vacuum sludge is reduced by supplying the raw sludge O by the pump 21 while discharging the desorbed liquid W by the predetermined amount by the drain pump 22. The raw sludge O supplied into the container 3 is subjected to solid-liquid separation in the tank.

  When dewatering the concentrated sludge S collected in such a manner as it floats on the upper part of the decompression vessel 3, the decompression vessel 3 is filled and the concentrated sludge S is sludged by the upper sludge discharge pump 23. It is discharged from the discharge pipe 9 to a dehydrator (not shown).

  Furthermore, according to the third embodiment, the concentrated sludge S after separation in the vacuum vessel 3 is allowed to float and stay for a long time, thereby thickening the floating separated solid layer in the vacuum vessel 3 that is a vacuum vessel. The concentration of the separated solid can be increased by utilizing the consolidation effect. Thereby, a decompression container can be used as a storage tank of high concentration sludge. In this case, when the concentrated sludge S floated in the decompression vessel 3 is discharged, it is preferably discharged by a positive displacement sludge discharge pump.

  In this third embodiment, the desorbed liquid W is discharged from the lower side of the decompression vessel 3, but the lower portion of the depressurized vessel 3 is formed in a conical shape symmetrical to the upper portion, and the desorbed liquid W is discharged from the center. However, the present invention is not limited to this embodiment.

  As described above, according to the continuous solid-liquid separators 1, 16, and 17 according to the first to third embodiments, the raw sludge O is continuously supplied into the decompression vessel 3 (sludge storage tank) and continuously solidified. Liquid separation becomes possible.

  Therefore, the waiting time in the stationary process and the decompression process is not required as in the prior art, and the raw sludge is continuously supplied into the decompression container 3 and the continuous operation can be efficiently performed.

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

  The continuous solid-liquid separation method and apparatus according to the present invention can perform solid-liquid separation of raw sludge continuously, so that it is useful in facilities for continuously solid-liquid separation of raw sludge to efficiently concentrate sludge.

It is a block diagram which shows the continuous solid-liquid separation apparatus which concerns on 1st Embodiment of this invention. (a)-(d) is a schematic diagram which shows the flow of the method of performing solid-liquid separation by performing a vacuum deaeration process with the continuous solid-liquid separator shown in FIG. (a), (b) is a block diagram which shows the continuous solid-liquid separator which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the continuous solid-liquid separation apparatus which concerns on 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Continuous solid-liquid separator 2 ... Raw sludge storage tank 3 ... Depressurization container 4 ... Supply pipe 5 ... Supply port 6 ... Discharge port 7 ... Discharge port 8 ... Discharge pipe 9 ... Sludge discharge pipe 10 ... Exhaust pipe 11 ... Discharge pipe DESCRIPTION OF SYMBOLS 12 ... On-off valve 13 ... Drainage tank 14 ... Flocculant supply part 15 ... Flocculant 16 ... Continuous solid-liquid separator 17 ... Continuous solid-liquid separator 18 ... Exhaust port 19 ... On-off valve 20 ... Exhaust pipe 21 ... Pump 22 ... Drain pump 23 ... Sludge discharge pump O ... Raw sludge S ... Concentrated sludge W ... Desorbed liquid L1-L4 ... Level meter M1-M3 ... Open / close valve PIC ... Pressure gauge

Claims (8)

  The raw sludge is supplied into a vacuum container that has been reduced to an internal pressure capable of degassing the raw sludge, the dissolved gas in the supplied raw sludge is foamed under reduced pressure, and the solid content of the sludge is accompanied with the foamed gas. The solid content is collected at the upper part of the vacuum container by being floated and separated into solid and liquid, and the solid content and the foamed gas collected at the upper part of the vacuum container are discharged from the upper part of the vacuum container; Control the discharge speed and supply speed of the operation of discharging the collected desorbed liquid from the lower part of the vacuum container and the operation of supplying the raw sludge into the vacuum container to reduce the pressure of the raw sludge in the vacuum container. A continuous solid-liquid separation method by vacuum degassing that is continuously performed to separate the solid and liquid.   The desorbed liquid discharged from the lower part of the vacuum container is discharged from a liquid discharge pipe that opens below the liquid level of the drain tank having a height difference of 10 meters or more downward from the vacuum container. The continuous solid-liquid separation method by reduced-pressure deaeration treatment according to claim 1, wherein the separated liquid is discharged from the reduced-pressure vessel by its own weight.   The continuous solidification by the vacuum degassing process according to claim 1 or 2, wherein the raw sludge is supplied into the vacuum vessel from a tangential direction of the wall of the vacuum vessel to form a swirl flow in the vacuum vessel. Liquid separation method.   By extending the discharge time of the solids collected at the top of the vacuum vessel until the pressure in the vacuum vessel rises to a predetermined pressure, the solids layer is thickened to increase the concentration effect by consolidation. The continuous solid-liquid separation method by the vacuum deaeration process of any one of Claims 1-3.   Dissolved gas in the raw sludge is foamed under reduced pressure, and the foamed gas is allowed to float with the solid content of the sludge so as to collect a solid content at the top to provide a vacuum container for solid-liquid separation. Provided with a discharge port for discharging the foaming gas and solids, a discharge port for discharging the desorbed liquid at the bottom of the decompression vessel, a supply port for supplying raw sludge to the side of the decompression vessel, Raw sludge to be supplied into the vacuum vessel by providing a control device for controlling the supply rate of the raw sludge supplied from the supply port into the vacuum vessel and the discharge rate of the solids and desorbed liquid discharged from the discharge port. A continuous solid-liquid separation device using vacuum degassing for continuously performing vacuum degassing.   A liquid discharge pipe is provided at the discharge port of the decompression container, and the lower end of the liquid discharge pipe is opened below the liquid level of the drain tank having a height difference of 10 meters or more downward from the decompression container. 6. The continuous solid-liquid separation device according to claim 5, wherein the desorbed liquid is discharged by its own weight.   The decompression deaeration process according to claim 5 or 6, wherein the supply port is arranged in a tangential direction of the wall of the decompression vessel, and a swirl flow is generated in the decompression vessel by the raw sludge supplied from the supply port. By continuous solid-liquid separator. A sensor for detecting the internal pressure is provided in the decompression container, and the solid content layer gathered on the upper part of the decompression container is thickened until the sensor detects that the pressure in the decompression container has risen to a predetermined pressure, thereby concentrating by consolidation. The continuous solid-liquid separation device according to any one of claims 5 to 7, wherein the effect is enhanced.

Images