JP2007090264A - Sludge concentration apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sludge concentration apparatus and method which enable a stable sludge thickening even if a target sludge concentration discharged into the sludge concentration apparatus changes, and further, can obtain thickened sludge in concentrated form which shows an extremely small change in concentration. <P>SOLUTION: The sludge concentration apparatus is provided with a screw cleaning a filtration screen portion inner surface formed in the periphery of a cylinder which separates the agglomerated sludge introduced from a sludge flocculation tank from a cylinder inner surface toward the outer surface to pass through, and at the same time, transporting the agglomerated sludge from an end of the cylinder to the other end to discharge as thickened sludge. The apparatus is further provided with a discharged quantity adjusting means which is provided on the other end of the cylinder, and turns a pressure value detected by a sludge pressure gauge detecting a pressure value which comes in the thickened sludge discharged by the screw to the predetermined value by controlling a discharge amount of the compressed thickened sludge. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, suspended solids and solid components (hereinafter “solid components”) contained in sludge are aggregated in a sludge coagulation tank, and then a clarified water component (hereinafter “water”) is separated from the aggregated sludge. The present invention relates to a sludge concentrating apparatus and a sludge concentrating method suitable for concentrating sewage.

  In order to discard or incinerate various sludges, water contained in the sludge is dehydrated by a dehydrator, and solid components and the like contained in the sludge are separated and taken out. However, sludge dewatering cannot be efficiently performed only by the capacity of the dewatering machine, and in order to efficiently perform sludge dewatering, it is necessary to concentrate the agglomerated sludge to a condensed sludge concentration suitable for dewatering treatment. Therefore, prior to the sludge dewatering treatment, sludge concentration processing is performed in which sludge is aggregated with a flocculant and the concentration of solid components and the like contained in the aggregated sludge (hereinafter referred to as “aggregated sludge concentration”) is increased.

Conventionally, for example, a rotary screen type sludge concentrating device shown in FIG. 8 or a screw press type sludge concentrating device shown in FIG.
In the rotary screen type sludge concentrator of FIG. 8, the sludge is introduced into the sludge agglomeration tank 2 by the introduction pump 1, and then added with a flocculant and stirred by the agitator 3 to become agglomerated sludge. This agglomerated sludge is introduced into the cylindrical body 4 arranged substantially horizontally. On the peripheral surface of the cylindrical body 4, a filtration screen portion 5 formed of a punching plate or a wedge wire is provided. Inside the cylindrical body 4, a spiral screw 7 is fixed by welding or the like in contact with the inner peripheral surface of the filtration screen portion 5, and the cylindrical body 4 is driven by a motor 8 to rotate. Then, the coagulated sludge introduced into the inside of the cylindrical body 4 is transferred by the spiral screw 7 and part of the moisture passes through the filtration screen portion 5 and is separated to the outside of the cylindrical body 4. On the other hand, the agglomerated sludge transferred by the spiral screw 7 is partly separated from water to be discharged as a concentrated agglomerated sludge. The separated liquid (water) thus separated is discharged from a separated liquid discharge port 9 a provided at the bottom of the outer container 9 that houses the cylindrical body 4.

In the above rotary screen type sludge concentrating device, the filter 10 is soiled and clogged due to the precipitation of solid components contained in the coagulated sludge, so the shower 10 sprays water on the filter screen 5 to remove the dirt. Wash.
In addition, in the screw press type sludge concentrating device of FIG. 9, sludge aggregated in the sludge aggregating tank is introduced into the cylindrical body 4 as in the rotary screen type sludge concentrating device, but the cylindrical body 4 arranged substantially horizontally is rotated. On the other hand, the point that the inner cylinder 6 inside the cylindrical body 4 and the helical screw 7 are driven by the motor 8 to rotate is greatly different. Then, the coagulated sludge introduced into the inside of the cylindrical body 4 is transferred by the helical screw 7, and part of the water passes through the filtration screen portion 5 provided in the cylindrical body 4 and the cylindrical body 4. On the other hand, the agglomerated sludge transferred to the outside by the helical screw 7 is partly separated and discharged as a concentrated agglomerated sludge. The separated liquid thus separated is discharged from a separated liquid discharge port 9 a provided at the bottom of the outer container 9 that houses the cylindrical body 4.

Also in this screw press type sludge concentrating device, the filtration screen part 5 is soiled and clogged with solid components contained in the coagulated sludge. This dirt is washed with water sprayed from the shower 10 onto the filter screen.
However, in the above-described sludge concentrating device, the water level of the coagulated sludge introduced into the cylindrical body 4 is between the lower part of the horizontally disposed cylindrical body 4 and the vicinity of the substantially central portion of the cylindrical body 4. Yes, only the lower part of the filtration screen part 5 and the vicinity thereof only separates moisture from the coagulated sludge. Therefore, in order to concentrate a larger amount of the coagulated sludge, it is necessary to enlarge the filtration screen unit 5 and the sludge concentrating device is enlarged. Moreover, the pressure required for the filtration in the filtration screen part 5 becomes high with the height of the coagulation sludge water surface inside the filtration screen part 5. When the pressure becomes higher than necessary, solid components and the like accumulated in the filtration screen portion 5 leak from the filtration screen portion 5 to the outside, and the filtration screen portion 5 is clogged with the leaked solid components and the like.

  In order to reduce such leaks and clogging, more flocculant must be added to the sludge in the sludge flocculation tank. Further, when clogging occurs, it is necessary to wash the filtration screen portion 5 with the shower 10, and it is also necessary to wash with the shower 10 solid components that leak from the filtration screen portion 5 and accumulate on the bottom surface of the outer container 9. . Furthermore, the concentration concentration in the sludge concentrator depends on the filterability of the aggregated sludge in the filtration screen unit 5 (the property of how much water is separated from the aggregated sludge). Moreover, since the filtration speed also changes depending on the water surface height of the coagulated sludge inside the filter screen unit 5 and clogging of the filter screen unit 5, it is difficult to adjust the coagulated sludge concentration to a predetermined concentration.

Therefore, the present applicant can use the entire surface of the filtration screen part to separate the moisture from the coagulated sludge in order to solve the above-mentioned problems, and therefore can be composed of a small cylindrical body. The size of the concentrating device can be reduced, the pressure related to the filtration in the filtration screen section does not become higher than necessary, the leakage of solid components, etc., and the clogging of the filtration screen section are difficult to occur. A sludge concentrating device and a sludge concentrating method capable of adjusting the concentration of the coagulated sludge to a predetermined concentration have been proposed (for example, see Patent Document 1).
Japanese Patent No. 3627809

  However, the above-described sludge concentrating device and the sludge concentrating method set the flow rates of the raw mud pump and the concentrated sludge pump that feed the raw mud into the coagulation tank. That is, the above-described sludge concentrating device and sludge concentrating method are operations for setting a concentration factor. That is, since the concentration factor is set in advance so as to be a predetermined value, the concentration of the coagulated sludge (hereinafter sometimes referred to as the concentrated sludge concentration) varies in proportion to the raw mud concentration. In this case, when the concentrated sludge concentration (concentration ratio) is set low, the influence of the raw sludge concentration is not significantly affected. On the other hand, when the concentrated sludge concentration is set high, the concentrated sludge concentration increases as the raw sludge concentration increases. Therefore, there is a problem that the concentrated sludge accumulates below the sludge concentrating device and the filter screen is clogged, making it difficult to concentrate the sludge.

In order to avoid such a phenomenon, the concentration factor should be set so that the filtration screen does not clog even when the raw mud concentration becomes high, but there is a problem that the average value of the concentration of the coagulated sludge becomes low . That is, the conventional sludge concentration apparatus and the sludge concentration method have a problem that they can be set only at a concentration lower than the optimum value of the concentration of the coagulated sludge.
Incidentally, the concentration ratio is the ratio of the raw sludge flow rate (Q1) introduced into the sludge concentrator and the concentrated sludge flow rate (Q2) discharged from the sludge concentrator, that is, the aggregate sludge before concentration in the sludge concentrator. It is the ratio of the concentration of solid components etc. in the coagulated sludge after concentration by the sludge concentrator with respect to the concentration of solid components etc. In other words, the concentration factor is
Concentration magnification = (Q1 / Q2)
Defined by Here, the flow rate is (cubic meter / hour, cubic meter / second, etc.).

  The present invention has been made in order to solve the above-described problems, and its purpose is to perform stable sludge concentration even if the concentration of raw mud charged into the sludge concentrator changes, and furthermore, An object of the present invention is to provide a sludge concentrating apparatus and a sludge concentrating method capable of obtaining a concentrated sludge having a high concentration with very little concentration change.

In order to solve the above-mentioned problems, the inventors pay attention to the pressure applied to the sludge (concentrated sludge) compressed by the sludge concentrating device, and detect the pressure applied to the concentrated sludge with a pressure sensor provided inside the cylindrical body. At the same time, a preliminary verification test was conducted under the following conditions in order to grasp the relationship with the concentration of the sludge to be concentrated.
(1) Concentrator: Filter tube diameter 150mm, height 600mm
(2) Sludge concentration: 0.4 to 0.8 [mass%] (varies within this concentration range)
(3) Flocculant: Polymer flocculant CLIFIX CP604 (manufactured by Kurita Kogyo Co., Ltd., dimethylaminoethyl methacrylate-based cationic polymer)
(4) Amount of processing: 4 m ³ / h
As a result, when the relationship between the concentration of the sludge concentrated in the sludge concentrator (concentrated sludge concentration) and the pressure value detected by the pressure sensor 30 is obtained, the relationship is as shown in FIG. When the concentrated sludge concentration is 5%, the pressure of the concentrated sludge detected by the pressure sensor 30 is 1 kPa, and when the concentrated sludge concentration is 7%, the pressure of the concentrated sludge detected by the pressure sensor 30 is 3 kPa. . From the result of this preliminary verification test, it was confirmed that the concentrated sludge concentration and the detection value of the pressure sensor 30 are in a linear relationship.

The sludge concentrating device of the present invention has been made to solve the above-described problems based on such knowledge, and the feature thereof is that the agglomerated sludge introduced from the sludge aggregating tank is concentrated, A sludge concentration device for obtaining concentrated sludge and separated liquid from agglomerated sludge,
A cylindrical body that is disposed below the position of the water surface of the sludge agglomeration tank and introduces the agglomerated sludge into the inside from one end thereof due to a water level difference, and the moisture of the introduced agglomerated sludge, A filtration screen portion formed on the circumferential surface of the cylindrical body that is separated and passed from the inner surface to the outer surface of the cylindrical body due to a difference in water level, and the inner surface of the filtration screen portion that is located inside the cylindrical body is cleaned. A screw that transfers the coagulated sludge from one end of the cylindrical body to the other end and discharges it as concentrated sludge, and contains a separation liquid that is separated from the filtration screen to the outside of the cylindrical body, and An outer container for immersing the cylindrical filtration screen in the separation liquid;
A separation liquid outlet provided in the outer container for discharging the separation liquid separated outside the cylindrical body;
The sludge concentration device is further provided at the other end of the cylindrical body, and detects a pressure value applied to the concentrated sludge compressed by the screw, and a pressure value detected by the sludge pressure gauge. And a discharge amount adjusting means for adjusting the discharge amount of the compressed concentrated sludge to a predetermined value.

  Therefore, in the above-described sludge concentrating device, the cylindrical body having the filtration screen portion formed on the peripheral surface is disposed at a position lower than the water surface position of the sludge agglomeration tank, and is used to store the separated liquid separated from the filtration screen portion. Submerged in a container. Therefore, since water can be separated from the aggregated sludge over the entire peripheral surface of the filtration screen portion, the cylindrical body can be downsized and the sludge concentrating device can be downsized.

  In addition, since the concentration of the concentrated sludge is linearly related to the pressure applied to the concentrated sludge compressed by the screw, this concentration is detected by a pressure sensor and concentrated so that the detected pressure value becomes a predetermined pressure. Since the amount of sludge discharged is adjusted and controlled, the concentrated sludge concentration can be kept constant even if the raw mud concentration changes. Further, since the pressure applied to the concentrated sludge is detected and adjusted so as to be constant, the filtration pressure does not increase more than necessary. Therefore, it is possible to reduce the leakage of solid components and the like in the filtration screen portion, and it is not necessary to add more flocculant to the sludge in the sludge aggregation tank in order to prevent the leakage.

  Furthermore, solid components and the like are prevented from accumulating inside the filtration screen by the screw that cleans the inside of the filtration screen and transports the coagulated sludge, and clogging does not occur in the filtration screen portion. Then, the filtration pressure can be maintained at a constant pressure by adjusting the discharge amount of the concentrated sludge, that is, the concentrated sludge concentration can be kept constant. That is, when the filtration pressure is kept constant without clogging in the filtration screen portion, the concentrated flocculated sludge having a more stable concentration rate is discharged. Further, since clogging does not occur, a shower and washing water for washing the filtration screen portion are not necessary.

However, although the solid component that leaks very slightly in the filtration screen portion settles on the bottom of the outer container, the sludge concentrating device together with the sludge concentrating device together with the liquid flow of the separating liquid from the separating liquid discharge port provided in the outer container It is discharged outside. This eliminates the need for a shower or washing water for washing the outer container.
Further, the sludge concentration method of the present invention was made to solve the above-mentioned problems, and the feature thereof is as follows:
A step of supplying sludge to the sludge agglomeration tank, adding a flocculant and stirring to obtain agglomerated sludge, and being placed at a position lower than the water surface of the sludge agglomeration tank, and filtering the agglomerated sludge by a water level difference A step of introducing the inside of the cylindrical body having the screen portion into the inside thereof, and a screw provided inside the cylindrical body, the inner surface of the filtration screen portion is cleaned and the introduced sludge is introduced into the cylindrical body. The filter screen part is submerged in an outer container containing the separated liquid, and a step of separating the moisture of the coagulated sludge by the filter screen part according to the difference in water level. In a sludge concentration method comprising a separated liquid discharge step of discharging the separated liquid from the outer container in a state where
A pressure detection step of detecting the pressure of the concentrated sludge from which the moisture of the agglomerated sludge is separated at the filtration screen and discharged at the other end of the cylindrical body by the screw;
A concentrated sludge discharging step of adjusting a discharge amount of the concentrated sludge discharged at the other end to make the pressure of the concentrated sludge detected by the pressure detecting means a predetermined pressure. Yes.

  Therefore, the sludge concentration method described above enables the concentration of sludge by a downsized sludge concentrator, and pressure detection of the pressure of the concentrated sludge separated at the filtration screen and discharged at the other end of the cylinder by the screw. The concentrated sludge discharge step adjusts the discharge amount of the concentrated sludge so that this pressure is constant. This is based on the fact that the pressure of the coagulated sludge and the coagulated sludge concentration are in a linear relationship as described above, and the present invention is a concentration method that always maintains a predetermined concentrated sludge concentration even if the raw mud concentration changes. Provide a sludge concentration method that discharges sludge.

  As described above, according to the sludge concentrating device and the sludge concentrating method of the present invention, attention is paid to the fact that the pressure applied to the sludge aggregated in the sludge aggregating device (concentration part pressure) is linearly related to the concentrated sludge concentration. The concentration sludge pump discharge power is controlled so that the pressure in the concentrator becomes the specified pressure, so even if the concentration of raw mud that is input to the sludge concentrator changes, stable sludge concentration should be performed. In addition, it is possible to obtain a concentrated sludge having a high concentration with very little change in the concentrated sludge concentration. Moreover, the entire surface of the filtration screen can be used to separate moisture from the flocculated sludge. Therefore, the sludge concentrating device can reduce the size of the sludge flocculating device, and the pressure related to filtration at the filtration screen is higher than necessary. It is difficult to cause leakage of solid components and clogging of the filtration screen, and since the sludge concentrator is operated while cleaning the filtration screen, it can prevent clogging of the filtration screen. it can.

Therefore, the sludge concentrating device and the sludge concentrating method of the present invention can aggregate sludge in the sludge agglomeration tank by adding a small amount of a flocculant, and the solid component adhering to the filtration screen or deposited on the bottom surface of the outer container can be showered. A very favorable effect can be obtained in the sludge concentrating apparatus and the sludge concentrating method which do not require washing.
Further preferably, the sludge concentrating apparatus and the sludge concentrating method of the present invention can adjust the aggregated sludge concentration inside the filtration screen to a predetermined concentration, and stabilize the concentration of the aggregated sludge to the aggregated sludge concentration suitable for dehydration treatment. Then, it can be highly concentrated in the sludge treatment such as concentrating and maintaining the concentration.

Hereinafter, a sludge concentration apparatus and a sludge concentration method according to a first embodiment of the present invention will be described with reference to the drawings.
FIG. 2 is a schematic configuration diagram showing a main part of the first embodiment of the sludge concentration apparatus according to the present invention. In FIG. 2, components having the same functions as those of the conventional sludge concentrating device shown in FIGS. 8 and 9 are denoted by the same reference numerals, and the description thereof is omitted.

  The sludge concentrating apparatus according to the first embodiment of the present invention includes a cylindrical body 11 arranged substantially vertically to introduce the coagulated sludge into the inside from its upper end (one end), and the inside of the cylindrical body 11. A shaft body 13 having a spiral screw 12 that is located concentrically and transfers aggregated sludge from the upper end portion (one end portion) 11a of the cylindrical body 11 to the lower end portion (other end portion) 11b, and the cylindrical body 11 and a substantially sealed outer container 15 that accommodates the filter screen unit 14 in a state where the filter screen unit 14 is submerged with a separation liquid separated from the coagulated sludge by the filter screen unit 14.

  The outer container 15 is mainly formed of, for example, a cylindrical body that is concentric with the cylindrical body 11. Moreover, the said filtration screen part 14 is formed in the surrounding surface between the upper end part 11a and the lower end part 11b of the cylindrical body 11 with a punching plate or a wedge wire etc. as shown in FIG. It is provided with holes or meshes having an inner diameter through which solid components or the like cannot pass.

  The shaft body 13 is supported by bearings at the upper end portion 11a and the lower end portion 11b of the cylindrical body 11, passes through the upper end portion 11a, and is connected to a motor 16 disposed above the upper end portion 11a. The spiral screw 12 included in the shaft body 13 rotates together with the shaft body 13 driven by the motor 16 and transfers the coagulated sludge introduced into the upper end portion 11a of the cylindrical body 11 to the lower end portion 11b. The spiral screw 12 has an outer shape of the spiral portion slightly smaller than the inner diameter of the filtration screen portion 14, and a slight gap is formed between the outer edge portion of the spiral screw 12 and the inner surface of the filtration screen portion 14. Therefore, the spiral screw 12 prevents solid components and the like contained in the coagulated sludge from adhering to the inner surface of the filtration screen portion 14, and peels them off from the inner surface of the filtration screen portion 14 when they adhere. Then, the inner surface of the filtration screen unit 14 is cleaned.

  In this sludge concentrating device, the sludge to be agglomerated is converted into agglomerated sludge through a process in which a flocculant is added in the sludge agglomeration tank 2 and agitated by the agitator 3. The position of the sludge water surface of the sludge agglomeration tank 2 (hereinafter sometimes referred to as “aggregation tank water surface”) is higher than the position of the filtration screen part 14 of the cylindrical body 11 of the sludge concentrator, and the difference in water level causes aggregation. Sludge is introduced from the sludge agglomeration tank into the inlet 11c provided at the upper end portion 11a of the cylindrical body 11.

Next, through this introduction step, the water introduced into the cylindrical body 11 and separated from the aggregated sludge by the filtration screen unit 14 is accommodated in the outer container 15. An upper connecting pipe 15c and a lower connecting pipe 15d are connected to the outer container 15 in the vicinity of the upper end portion 11a and the lower end portion 11b, respectively, and the connecting pipes 15c and 15d are connected to the separation liquid tank 19, respectively. Yes.
The upper connecting pipe 15c serves to remove the floating scum when the floating scum is generated in the filtrate that has passed through the filtration screen portion 14 and to release air when the filtration screen portion 14 is back-washed with air. Take on. On the other hand, the lower connecting pipe 15d plays a role of discharging the precipitated floc that has leaked into the filtrate that has passed through the filtration screen portion 14. That is, these connection pipes 15c and 15d are configured to always discharge the separation liquid and prevent the floating scum and sedimentation floc from accumulating in the outer container 15. A separation liquid discharge pipe 19 a is provided at the upper end of the separation liquid tank 19.

  On the other hand, a sludge pressure gauge (pressure sensor) 30 for detecting the pressure value of the aggregated sludge discharged to the lower end portion 11b in the cylindrical body 11 by the helical screw 12 is provided at the lower end portion 11b in the cylindrical body 11. Yes. Further, a concentrated sludge discharge pipe 18 (concentrated sludge discharge passage) is connected to a discharge port (concentrated coagulated sludge discharge port) 11d provided at the lower end portion 11b in the cylindrical body 11 to discharge the sludge. A pump 20 is provided.

  The pressure value of the coagulated sludge detected by the pressure sensor 30 is given to the pump adjusting unit 31 to adjust the flow rate (sludge extraction amount) of the sludge discharge pump 20 so that the pressure value of the coagulated sludge becomes a predetermined pressure. Specifically, assuming that the concentration of the coagulated sludge flowing into the cylindrical body 11 from the sludge coagulation tank 2 is constant, the amount of concentrated sludge discharged from the cylindrical body 11 is increased when the discharge amount of the sludge discharge pump 20 is increased. Since it increases, the concentration pressure of the coagulated sludge at the lower end portion 11b of the cylindrical body 11 is reduced. On the other hand, if the discharge amount of the sludge discharge pump 20 is decreased, the amount of the coagulated sludge discharged from the cylindrical body 11 is decreased and the condensed sludge is concentrated. Pressure increases. That is, the sludge discharge pump 20 plays a role of setting an optimum filtration pressure in the process of separating water from the coagulated sludge.

In this way, the coagulated sludge is transferred through the inside of the filtration screen portion 14 and becomes concentrated sludge through a concentration step in which a part of the water is separated, and is discharged from the discharge port 11d provided in the lower end portion 11b in the cylindrical body 11. .
In general, the sludge concentration apparatus and the sludge concentration method of the present invention configured as described above are characterized in that the pressure sensor (sludge pressure gauge) 30 provided at the lower end portion 11b in the cylindrical body 11 is the lower end. A pump adjustment unit that detects the pressure value applied to the concentrated sludge compressed by the unit 11b and adjusts the discharge amount of the concentrated sludge discharged from the cylindrical body 11 so that the pressure value detected by the pressure sensor 30 becomes a predetermined pressure. 31 is provided.

With regard to the sludge concentration apparatus and the sludge concentration method of the present invention having such characteristics, the inventors conducted a verification test for verifying the effect under the same conditions as the preliminary verification test described above.
Incidentally, when the pressure of the concentrated sludge detected by the pressure sensor 30 in the preliminary verification test described above is 2 kPa and the concentrated sludge concentration exceeds 6%, the concentrated sludge accumulates at the lower end portion 11b of the cylindrical body 11, and the filtration screen portion 14 Clogging occurred and operation became difficult. Therefore, in the case of the above conditions, the detected value of the pressure sensor 30 is 2 kPa, and the flow rate of the sludge discharge pump 20 is controlled so that the pump adjustment unit 31 does not exceed this pressure value.

  Based on the results of the preliminary verification test described above, a 24-hour continuous operation test was conducted to compare the effects of the conventional sludge concentrator and the sludge concentrator of the present invention. In the raw mud of this continuous operation test, the raw mud concentration varied between 0.4 and 0.8% as shown in FIG. 4, and the average concentration was 0.58%. That is, the raw mud sludge concentration reached a minimum value of 0.4% around 6 o'clock, and the raw mud sludge concentration reached a maximum value of 0.8% around 11 o'clock. In addition, the raw mud sludge concentration showed a maximum value around 19:00, while it showed a minimum value around 3 o'clock, around 15:00 and around 22:00.

Now, it is necessary to compress the sludge so that the concentrated sludge concentration does not exceed 6% so that the operation can be continued without clogging the filtration screen portion 14 from the result of the preliminary verification test. Therefore, the amount of concentrated sludge of the conventional sludge concentrating device that sets the concentration rate is
0.8% × ^{4m 3} /h÷6%=0.53m 3 /h(7.5 fold concentrated)
It is necessary to.

On the other hand, the sludge concentrator of the present invention sets the pressure value in the pump adjustment unit 31 so that the pressure detected by the pressure sensor 30 does not exceed 2 kPa (the concentrated sludge concentration is 6%) as described above, and the verification test. Carried out.
As a result, as shown in FIG. 5, in the conventional sludge concentration apparatus, a change in the concentrated sludge concentration similar to the change in the raw sludge concentration is observed, the concentration fluctuates in the range of 3 to 6%, and the average sludge concentration Was 4.3%. On the other hand, the sludge concentration apparatus of the present invention has a concentrated sludge concentration within a range of 5.8 to 6%, an average sludge concentration of 5.9% and hardly changes, and the concentrated sludge concentration is high throughout 24 hours. I was able to get sludge. The flow rate of the concentrated sludge in the sludge concentration apparatus of the present invention varied in the range of 0.28 to 0.53 m ³ / h. This is because, as described above, the sludge concentrator of the present invention variably controls the discharge flow rate of the sludge discharge pump 20 so that the concentrated sludge concentration becomes constant.

Thus, the sludge concentration apparatus and the sludge concentration method of the present invention can maintain the concentrated sludge concentration constant even if the raw sludge concentration changes, and provide high concentration concentrated sludge with little change in concentrated sludge concentration for a long time. It was confirmed that it was obtained stably over a long period of time.
Next, FIG. 6 shows an example in which the first embodiment of the present invention is modified. In this modification, components having the same functions as those of the sludge concentrating device shown in FIG.

  The modified example of the first embodiment is different from the first embodiment described above in that the coagulated sludge that has undergone the process of adding the coagulant in the sludge coagulation tank 2 and stirring it with the stirrer 3 is introduced into the inlet. While being introduced from below the cylindrical body 11 of the concentrated sludge apparatus 11c, the aggregated sludge concentrated on the upper end portion 11a in the cylindrical body 11 by the helical screw 12 was provided on the upper end portion 11a in the cylindrical body 11. It exists in the point discharged | emitted from the discharge port (concentrated aggregation sludge discharge port) 11d.

  Also in the modified example configured as described above, the sludge pressure gauge (pressure sensor) 30 detects the pressure value of the coagulated sludge concentrated on the lower end portion 11b in the cylindrical body 11 by the helical screw 12, and this pressure is a predetermined value. Since the pump adjusting unit 31 controls the discharge power of the sludge discharge pump 20 so that the pressure is increased, stable sludge concentration can be performed even if the concentration of the raw sludge input to the sludge concentrator changes. As a result, it is possible to obtain a concentrated sludge having a high concentration with very little change in concentration.

Next, FIG. 7 shows a second embodiment of the present invention. In this 2nd Embodiment, the component which has the same function as the sludge concentration apparatus shown in FIG. 2 and FIG. 6 is attached | subjected, and the description is abbreviate | omitted.
The second embodiment is different from the above-described embodiment in that the cylindrical body 11 is positioned substantially horizontally. An exhaust pipe 15 a is provided on the ceiling portion of the outer container 15 (the ceiling portion of the peripheral surface portion of the cylindrical body 11). The air extraction pipe 15a has an opening at a position higher than the sludge water surface of the sludge agglomeration tank 2, for example, so that the separation liquid stored in the outer container 15 does not leak, and the cylindrical body 11 and the outer container 15 It plays the role of venting the gas generated inside to the outside of the sludge concentrator. For example, the air extraction pipe 15a can also discharge air to the outside of the sludge concentrating device when the air backwashing is performed to remove the clogging of the filtration screen unit 14.

  In addition, a separation liquid discharge port 15 b is provided at the bottom on the end side of the outer container 15. A separation liquid discharge pipe (separation liquid discharge path) 17 connected to the separation liquid discharge port 15b rises upward from the separation liquid discharge port 15b, and includes a separation liquid discharge portion 17a at an upper portion thereof. The position (h2) of the separation liquid discharge water surface in the separation liquid discharge part 17a is lower than the position (h1) of the coagulation tank water surface. Here, the filtration screen part 14 is disposed at a position lower than the position (h1) of the water surface of the coagulation tank, and the filtration screen part 14 is in a state of being submerged in the separation liquid stored in the outer container 15. .

  According to the sludge concentrating device and the sludge concentrating method according to the second embodiment of the present invention configured as described above, the lower end portion 11b in the cylindrical body 11 is formed by the helical screw 12 as in the first embodiment described above. The sludge pressure gauge (pressure sensor) 30 detects the pressure value of the coagulated sludge concentrated on the pump, and the pump adjustment unit 31 adjusts the discharge power of the sludge discharge pump 20 so that the pressure of the concentration unit becomes a predetermined pressure. Even if the concentration of the raw sludge charged into the sludge concentrator changes, stable sludge concentration can be performed and, in turn, a highly concentrated concentrated sludge with very little change in the concentrated sludge concentration is obtained. be able to.

  In the sludge concentration apparatus and the sludge concentration method according to the present invention described above, an inorganic flocculant and an amphoteric polymer flocculant may be used in combination instead of the polymer flocculant. Further, the sludge concentrating device and the sludge concentrating method according to the present invention are not limited to the embodiments described above, and can be carried out by being modified without departing from the gist thereof.

It is a graph which shows the relationship between the pressure added to the concentrated sludge, and concentrated sludge density | concentration. It is a principal part schematic block diagram of the sludge concentration apparatus which concerns on the 1st Embodiment of this invention. It is an external view of the cylindrical body of the sludge concentration apparatus of FIG. 2, and the filtration screen part provided in the surrounding surface. It is a graph which shows the time change of the raw mud density | concentration used for the evaluation test. It is a graph which shows the time change of the concentration sludge density | concentration when the raw mud which the raw mud density | concentration shown in FIG. 4 changes temporally is thrown into each of the sludge concentration apparatus of this invention, and the conventional sludge concentration apparatus. It is a principal part schematic block diagram of the modification of the sludge concentration apparatus which concerns on the 1st Embodiment of this invention. It is a principal part schematic block diagram of the sludge concentration apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic diagram which shows the conventional rotary screen type sludge concentration apparatus. It is a schematic diagram which shows the conventional screw press type sludge concentration apparatus.

Explanation of symbols

1 Introduction pump 2 Sludge coagulation tank
11 Cylindrical body 11a One end (upper end) of the cylindrical body
11b The other end (lower end) of the cylindrical body
11c Inlet 11d Discharge 12 Spiral screw 14 Filtration screen 15 Outer container 15b Separation liquid discharge 18 Concentrated sludge discharge pipe 19 Separation liquid tank 19a Separation liquid discharge pipe 20 Sludge discharge pump 30 Pressure sensor 31 Pump adjustment part

Claims (2)

A sludge concentrating device that concentrates agglomerated sludge introduced from a sludge agglomeration tank and obtains a concentrated sludge and a separated liquid from the agglomerated sludge,
A cylindrical body that is disposed below the position of the water surface of the sludge agglomeration tank, and introduces the agglomerated sludge into the inside from one end thereof by a water level difference;
A filtration screen portion formed on the peripheral surface of the cylindrical body that allows the moisture of the introduced sludge to be separated and passed from the inner surface to the outer surface of the cylindrical body due to the water level difference;
A screw that is located inside the cylindrical body, cleans the inner surface of the filtration screen part, transfers the aggregated sludge from one end of the cylindrical body to the other end, and discharges it as concentrated sludge,
An outer container for containing a separation liquid separated from the filtration screen portion outside the cylindrical body, and submerging the filtration screen portion of the cylindrical body in the separation liquid;
A separation liquid outlet provided in the outer container for discharging the separation liquid separated outside the cylindrical body;
The sludge concentration device is further provided at the other end of the cylindrical body, and detects a pressure value applied to the concentrated sludge compressed by the screw, and a sludge pressure gauge.
A sludge concentrating device comprising: a discharge amount adjusting means for adjusting a pressure value detected by the sludge pressure gauge to a predetermined value by adjusting a discharge amount of the compressed concentrated sludge. Supplying sludge to the sludge agglomeration tank, adding a flocculant and stirring to obtain agglomerated sludge;
A step of being arranged at a position lower than the water surface of the sludge agglomeration tank, and introducing the agglomerated sludge into the inside from one end of a cylindrical body having a cylindrical filtration screen portion by a water level difference;
The screw provided inside the cylindrical body cleans the inner surface of the filtration screen part, and transfers the introduced coagulated sludge to the other end of the cylindrical body. A step of separating the moisture of the coagulated sludge;
A separation liquid discharging step of discharging the separation liquid from the outer container in a state where the filtration screen portion is submerged in the outer container containing the separated separation liquid;
A pressure detection step of detecting the pressure of the concentrated sludge from which the moisture of the agglomerated sludge is separated at the filtration screen and discharged at the other end of the cylindrical body by the screw;
A concentrated sludge discharge step of adjusting a discharge amount of the concentrated sludge discharged at the other end to make the pressure of the concentrated sludge detected by the pressure detection step a predetermined pressure. To concentrate sludge.

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