JP2020146614A - Sludge treatment system and sludge treatment method - Google Patents

Abstract

To provide a sludge treatment system and a sludge treatment method that not only enable a stable system operation, but also alleviate problems of a technician shortage or technology succession.SOLUTION: A coagulation/mixing device 4 generates a coagulation floc C by mixing a coagulant B with a sludge A to be treated generated in a water treatment system and supplied. A flow meter SF1 and a concentration meter SD1 measure a flow rate and a concentration of the sludge A to be treated supplied to the coagulation/mixing device 4. A sludge dehydrator 7 separates and removes water from the coagulation floc C to produce a dehydrated cake G having a reduced water content, and discharges a dehydrated filtrate H corresponding to water. A flow meter SF3 and a SS concentration meter SD2 measure a flow rate and SS concentration of the dehydrated filtrate H. A control device 11 calculates a water content of the dehydrated cake G based on measured values of the flow meter SF1 and the concentration meter SD1 and the measured values of the flow meter SF3 and the SS concentration meter SD2.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sludge treatment system and a sludge treatment method, for example, a clean water treatment or a sewage treatment using a coagulant, and a coagulation admixture or sludge treatment technique in the field of industrial wastewater.

In Patent Document 1 and Patent Document 2, the water content of the dehydrated sludge from the screw press dehydrator is measured by a moisture meter, and the back pressure and the screw rotation speed are adjusted so that the water content is equal to or less than a predetermined value. A sludge treatment system that prioritizes back pressure adjustment is shown. In Patent Document 3, a floc is imaged with a stock solution supply pipe that supplies a fixed amount of undiluted solution to a dehydrator, and a flocculant is added so that the average analysis area of the imaged flock is within the range of a reference area determined in advance on a trial basis. A coagulant injection control method for controlling the rate and the number of stirrings is shown. Non-Patent Document 1 discloses a hybrid press-fit screw press in which a hydrophilic screen is used for the concentrating part screen of the dehydrator.

Japanese Patent No. 5716049 Japanese Patent No. 5989819 Japanese Patent No. 4328983

Inuzuka and 3 others, "Examples of application of hydrophilic screens in hybrid press-fit screw presses", 55th Sewerage Research Presentation, N-10-1-6

In general, sludge treatment systems are often operated by the personal judgment of skilled technicians who have a thorough understanding of the status of facilities and equipment. However, in recent years, due to social backgrounds such as the aging population and the shortage of the working population, the shortage of technicians has made it difficult to pass on the technology. Therefore, automation of the sludge treatment system is desired. In this case, for example, it is conceivable to use the techniques of Patent Documents 1 to 3 for local automation.

However, in the method using a moisture meter as in Patent Documents 1 and 2, sufficient accuracy may not be obtained, and further, not only the water content but also the SS (Suspended Solids) recovery rate is controlled. Is desired. Further, in the method using a camera as in Patent Document 3, if sludge adheres to the measuring portion, accurate evaluation becomes difficult, so that frequent maintenance may be required. Further, even if the techniques of Patent Documents 1 to 3 are used, a certain amount of personnel is still required in some processes, and there is a possibility that the problem of shortage of engineers and the problem of technology succession cannot be sufficiently alleviated.

The present invention has been made in view of the above, and one of the objects thereof is to provide a sludge treatment system and a sludge treatment method capable of alleviating the problem of shortage of technicians or technology succession. is there.

The above and other objects and novel features of the present invention will become apparent from the description and accompanying drawings herein.

A brief description of typical embodiments of the inventions disclosed in the present application is as follows.

The sludge treatment system according to one embodiment includes a coagulation and mixing device, a first flow meter and a first densitometer, a sludge dehydrator, a second flow meter and a second densitometer, and a control device. Has. The coagulation / mixing apparatus supplies the sludge to be treated generated in the water treatment system, and mixes the coagulant with the sludge to be treated to generate coagulation flocs. The first flow meter and the first densitometer measure the flow rate and the concentration of the sludge to be treated supplied to the coagulation and mixing apparatus, respectively. The sludge dehydrator separates and removes water from the aggregated flocs to produce a dewatered cake with a reduced water content, and discharges a dewatered filtrate corresponding to the water content. The second flow meter and the second densitometer measure the flow rate of the dehydrated filtrate and the SS concentration, respectively. The control device calculates the water content of the dehydrated cake based on the measured values of the first flow meter and the first densitometer and the measured values of the second flow meter and the second densitometer.

In a typical sludge treatment system according to the present invention, sludge to be treated generated in a water treatment system is supplied, and the sludge to be treated is mixed with a coagulant to generate agglomerated flocs, and the sludge is supplied to the coagulation and mixing device. A dewatered cake with a reduced water content is produced by separating and removing water from the first flowmeter and the first densitometer, which measure the flow rate and concentration of the sludge to be treated, respectively, and the aggregated floc, which corresponds to the water content. A sludge dehydrator that discharges the dewatered filtrate, a second flow meter and a second densitometer that measure the flow rate and SS concentration of the dewatered filtrate, and measured values of the first flow meter and the first densitometer, respectively. It has a control device for calculating the water content of the dehydrated cake based on the measured values of the second flow meter and the second densitometer.

This system is further installed between the coagulation and mixing device and the sludge dehydrator, and has a sludge concentration trough that generates concentrated cohesive flocs by increasing the sludge concentration of the cohesive flocs generated by the coagulation and mixing device. The sludge concentration trough is the upper bottom, which is installed at an angle of 30-70 ° to the horizontal plane and separates and drains moisture from the transferred aggregate flocs, and the lower bottom, which is the concentration discharged by the screen. It is preferable to have a bottom plate for mixing the trough separation liquid with the dehydration filtrate of the sludge dehydrator. Further, the device of this sludge concentration trough is widely effective not only as the above-mentioned typical sludge treatment system but also as a device "installed between a coagulation mixing device and a sludge dehydrator". Further, here, the screen has a plurality of screen regions having different mesh widths of the moisture discharge port, and the mesh width of the screen region on the coagulation / mixing device side is larger than the mesh width of the screen region on the sludge dehydrator side. Larger is desirable. Further, the screen is preferably water-repellent or water-repellent and oil-repellent.

Here, in addition to the constituent members such as the screen constituting the sludge concentration trough, there are agglomerated flocs or contact points with the sludge to be treated, that is, the inner surface of the coagulation mixing tank, the stirring shaft of the stirrer, the stirrer propeller, and the aggregating flocs of the dehydrator. Automatically during stop flow by applying water-repellent treatment or water-repellent oil-repellent treatment that can prevent the adhesion of aggregated flocs and supply sludge to the supply section, screws, screens, back pressure plate section, dehydration filtrate trough, etc. It is possible to significantly reduce the cleaning work.

The surface treatment of the aggregated flocs and sludge to be treated is a metal-coated one, a metal-coated one, a fluorine-based or / and a silicone-based or water-repellent treatment by vapor deposition, but a fluorine-based resin or / and. The material itself such as silicone resin may be changed, and if it has a water-repellent or water-repellent oil-repellent effect, the treatment method and material do not matter. For example, in the case of silicone type, the side chain of the siloxane structure is oriented with a methyl group, and in the case of fluorine type, PTFE, PFA, FEP, etc., which have an oil-repellent effect as well as water repellency, for example, industrial wastewater containing oil. It is effective for application in such cases.

Further, the sludge treatment system of the present invention has a coagulation flock measuring device for measuring the size of coagulation flocs generated by the coagulation / mixing device, and the coagulation / flock measuring device transmits sound waves into the coagulation / mixing device to coagulate / mix. It is effective to have an acoustic transmitter / receiver that receives the reflected wave from the aggregated floc in the device and an acoustic measuring device that performs signal processing on the reflected wave received by the acoustic transmitter / receiver. Is effective not only in the above-mentioned typical sludge treatment system.

On the other hand, in a typical sludge treatment method according to the present invention, a coagulation / mixing device receives a supply of sludge to be treated generated in a water treatment system, mixes a coagulant with the sludge to be treated, and stirs at a predetermined stirring intensity. A coagulation-mixing step to generate coagulated flocs and a sludge dehydrator separates and removes water from the cohesive flocs to generate a dehydrated cake with a reduced water content, which is then stored in a hopper and corresponds to the water. It has a dewatering step of discharging the dewatered filtrate, and the dewatering step measures the flow rate and concentration of the sludge to be treated supplied to the coagulation and mixing tank by a predetermined measuring instrument, and the flow rate and SS concentration of the dewatered filtrate. The water content of the dehydrated cake is calculated by the control device based on the measured values of the first step and the water content is compared with the predetermined water content standard value, and the water content is the water content standard value. It is characterized by having a second step of changing the operating conditions of the sludge dewatering machine when the above conditions are not satisfied.

In the sludge treatment method of the present invention, in the agglomeration mixing step, the third step in which the agglomeration flock measuring device measures the size of the agglomeration flocs and the control device compares the size of the agglomeration flocs with a predetermined size reference value. However, when the size of the agglomerated flocs does not satisfy the size reference value, it may have a fourth step of changing at least one of the supply amount of the sludge to be treated, the supply amount of the aggregating agent, and the stirring strength. It is valid. In some cases, the fourth step may be preceded by the second step.

Further, in the sludge treatment method of the present invention, in the dehydration step, the control device further calculates the SS recovery rate based on the measured value of the first step, and sets the SS recovery rate and the predetermined recovery rate reference value. By comparison, it is also effective to have a fifth step of changing the operating conditions of the sludge dewatering machine when the SS recovery rate does not meet the recovery rate reference value.

In the sludge treatment method of the present invention, the dewatering step includes a sixth step in which the weight measuring device measures the weight of the dewatered cake stored in the hopper, and in the sludge treatment method, the control device is the sixth step. Compare the weight of the dehydrated cake measured in step 1 with the predetermined weight standard value, and when the weight of the dehydrated cake meets the weight standard value, start cleaning with the coagulation mixer or the automatic cleaning device installed in the sludge dehydrator. It is also effective to have a cleaning process that issues orders.

Further, in the sludge treatment method of the present invention, the sludge dehydrator is a screw press type device including a screw and a dewatered cake discharge port from which the dewatered cake is discharged, and the control device dewaters the sludge in the second step. When changing the operating conditions of the machine, it is also effective to change at least one of the rotation speed of the screw and the opening area of the dewatered cake discharge port.

As described above, the present invention ultimately aims at labor saving in dehydration process control, and the above systems or treatment methods may be appropriately combined.

Although the term sludge is used in the specification of the present application, the treatment target of the present invention is not limited to sludge, but mud-like substances, for example, slurry-like substances flowing in the processes of food factories and chemical factories, and slurry-like industrial wastes. It also includes those containing solid matter in liquid and those containing solid matter.

According to the sludge treatment system of the above-described embodiment, not only stable operation of the system becomes possible, but also the problem of shortage of technicians or technology succession can be alleviated.

It is the schematic which shows the structural example of the sludge treatment system by one Embodiment of this invention, and the example of the processing content of the sludge treatment method. It is a flow chart which shows an example of the detailed processing contents of the control device in the sludge treatment system of FIG. It is a flow chart which shows an example of the detailed processing contents of the control device in the sludge treatment system of FIG. It is a figure which shows the detailed arrangement example of the sludge concentration trough in FIG. (A), (b) and (c) are diagrams showing a detailed configuration example of the sludge concentration trough in FIG. It is a flow chart which shows an example of the operation method in the sludge treatment system which becomes the comparative example of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in all the drawings for explaining the embodiment, in principle, the same members are designated by the same reference numerals, and the repeated description thereof will be omitted.

<< Outline of sludge treatment system and sludge treatment method >>
FIG. 1 is a schematic view showing a configuration example of a sludge treatment system according to an embodiment of the present invention and an example of treatment contents of a sludge treatment method. Generally, sludge generated in a water treatment system is concentrated by gravity, and in some cases, undergoes a sludge digestion step, is stored as sludge A to be treated in a sludge storage tank, and is supplied to the sludge treatment system of FIG. In the sludge treatment system of FIG. 1, after the aggregated floc C is generated in the coagulation and mixing step, the volume is reduced to the dehydrated cake G in the dewatering step, and the sludge is carried out of the site. The carried-out dehydrated cake G is then disposed of as waste or recycled as a material such as compost or cement material.

Further, in the example of FIG. 1, a concentration step of generating concentrated aggregated flocs by increasing the sludge concentration of aggregated flocs C is provided between the agglomeration mixing step and the dehydration step. The coagulation / mixing step is performed by the coagulation / mixing device 4, the concentration step is performed by the sludge concentration trough 6, and the dehydration step is performed by the sludge dewatering machine 7.

First, the coagulation / mixing step will be described. The sludge supply pump P1 to be treated controls the supply amount of the sludge A to be treated, and supplies the sludge A to be treated with the controlled supply amount to the coagulation / mixing device 4. At this time, the flow meter SF1 and the concentration meter SD1 measure the flow rate and the concentration of the sludge A to be treated in-line to supply the sludge A to be treated to the coagulation / mixing device 4. The coagulation / mixing device 4 mixes the coagulant B with the sludge A to be treated and stirs it with a predetermined stirring strength to form a coagulation floc C. At this time, the coagulant supply pump P2 controls the addition amount of the coagulant B stored in the coagulant tank 2, and transfers the coagulant B whose addition amount is controlled to the downstream side of the flow meter SF1 and the concentration meter SD1. It is added indirectly from the piping line or directly to the coagulation / mixing device 4.

In this example, the amount of the coagulant B added is measured by the flow meter SF2, and is used for controlling the coagulant supply pump P2 via the control device 11. However, as long as it can be confirmed in advance that the addition amount can be controlled with high accuracy by the coagulant supply pump P2, the installation of the flow meter SF2 does not matter. Considering the mixing of the sludge A to be treated and the coagulant B, it is desirable to supply the sludge in the pipe, but if the coagulation and miscibility can be mixed, the addition position is not particularly limited. The measured values of the flow meter SF1, the densitometer SD1, and the flow meter SF2 are sent to the control device 11, respectively.

As the coagulant B, a polymer coagulant is generally used in sludge dewatering applications, but in some cases, it may be used in combination with an inorganic coagulant such as polyiron to form an organic or inorganic two-component drug. It may be a note. Further, the number of added chemical species is not particularly limited as long as it can sufficiently form aggregated floc C. The coagulation / mixing device 4 includes a coagulation / mixing tank 41 and a stirring device 42 including a driving device M1. The drive device M1 controls the stirring intensity of the stirring device 42. The coagulation / mixing device 4 mixes the sludge A to be treated to which the coagulant B is added in the coagulation / mixing tank 41 using a stirrer 42 to generate coagulation floc-generated water D containing coagulation flocs C.

Here, the size of the agglomerate flock C is measured by the agglomeration flock measuring device 5. The cohesive flock measuring device 5 includes an acoustic transmitter / receiver 52 and an acoustic measuring device 51. The acoustic transmitter / receiver 52 is installed below the water surface of the coagulation / mixing tank 41, transmits sound waves into the coagulation / mixing tank 41, and receives reflected waves from the coagulation flocs C in the coagulation / mixing tank 41. The acoustic measuring device 51 performs signal processing on the reflected wave received by the acoustic transmitter / receiver 52. For example, the acoustic measuring device 51 generates image data of the aggregated floc C based on the intensity, delay time, phase, etc. of the reflected wave. The control device 11 detects the flock size, flock density, and the like by performing image processing on the image data of the aggregated flock C.

Next, the concentration step will be described. The floc-generated water D generated by the coagulation-mixing device 4 overflows in the coagulation-mixing tank 41 and is supplied to the sludge concentration trough 6 installed in an inclined state. The sludge concentrating trough 6 is provided with a screen 62, and by separating water from the floc-generated water D using the screen 62, a concentrated coagulated floc in which the sludge concentration of the coagulated floc C is increased is generated and transferred to the sludge dehydrator 7. To do. On the other hand, the sludge concentrated trough 6 supplies the separated concentrated trough separation liquid E from the screen 62 to the dehydration filtrate trough 74 via the concentrated trough separation liquid pipe 61.

Subsequently, the dehydration step will be described. The sludge dehydrator 7 includes a screw 73, a drive device M2 for rotating and driving the screw 73, a screen 72, a dehydration filtrate trough 74, and a back pressure portion clearance adjusting device 8. The back pressure unit clearance adjusting device 8 includes a back pressure plate 81, a displacement sensor 82, a compressor 83, a solenoid valve 84, and an air cylinder 85. The sludge dehydrator 7 generally produces a dehydrated cake G having a reduced water content by separating and removing water from the concentrated aggregated flocs C (concentrated aggregated flocs), and then stores the dehydrated cake G in the hopper 101. , The dehydrator filtrate F corresponding to water is discharged to the dehydration filtrate trough 74 via the screen 72.

Specifically, the concentrated and agglomerated flocs transferred to the sludge dewatering machine 7 are transferred to the side opposite to the sludge supply side by the screw 73 rotationally driven by the drive device M2, and are consolidated by the outlet resistance of the back pressure plate 81. .. As a result, the concentrated aggregate flocs are separated into the dehydrator filtrate F and the dehydrated cake G via the screen 72. At this time, the back pressure portion clearance adjusting device 8 adjusts the position of the back pressure plate 81 via the solenoid valve 84 and the air cylinder 85 based on the compressed air generated by the compressor 83, so that the dehydrated cake G is discharged. Adjust the opening area of the dewatered cake outlet.

At this time, the displacement sensor 82 measures the position of the back pressure plate 81 and transmits the measurement data to the control device 11 so that the opening area becomes appropriate, and the control device 11 appropriately refers to the measurement data. The solenoid valve 84 is controlled so as to have a large opening area. The displacement sensor 82 may measure the amount of displacement at the position of the back pressure plate 81 in either contact or non-contact, and the measurement method is not particularly limited.

Further, as a sludge dewatering method, a belt press method, a multiple disk method, a centrifugal method and the like are generally known in addition to such a screw press method, and any method is not used. However, from the viewpoint of maintainability and automation, the screw press method is desirable. In the case of the screw press method, the water content of the dehydrated cake G can be controlled by at least one of the rotation speed of the screw 73 and the opening area (position of the back pressure plate 81) of the dehydrated cake discharging portion.

The concentrated trough separation liquid E from the sludge concentrated trough 6 and the dehydrator filtrate F from the sludge dehydrator 7 are combined as the dehydration filtrate H in the dehydration filtrate trough 74. The flow meter SF3 and the SS concentration meter SD2 measure the flow rate and SS concentration of the dehydrated filtrate H, respectively. At this time, the SS densitometer SD2 does not have to directly measure the SS concentration, and there is no problem even if the measured turbidity is converted to the SS concentration by using a turbidity meter that has been correlated with the SS concentration in advance. The measured values of the flow meter SF3 and the SS densitometer SD2 are sent to the control device 11, respectively.

From the sludge dehydrator 7, the dehydrated dehydrated cake G is discharged via the dehydrated cake discharging section, and the discharged dehydrated cake G is stored in the dehydrated cake storage hopper 10 via the dehydrated cake transfer conveyor 9. The dehydrated cake storage hopper 10 includes a hopper-101 and a weight measuring device 102. The weight measuring device 102 measures the weight of the dehydrated cake G stored in the hopper-101. When this weight reaches a predetermined weight reference value, the series of steps shown in FIG. 1 is completed. Further, the dehydrated cake G stored in the hopper-101 is carried out of the site and then disposed of as waste or recycled as a material such as compost or cement material.

Here, the sludge A to be treated is typically sludge generated in a water treatment system for sewage. In the following, this sewage sludge will be described as an example. However, the sludge treatment system of FIG. 1 is not limited to this, and can be applied to industrial wastewater including sewage, tap water, industrial water facilities, and the like having a coagulation / mixing step and / or a dehydration step. In particular, the coagulation and mixing process can be applied to solid-liquid separation for SS and turbidity reduction in water supply facilities, solid-liquid separation tanks for SS and turbidity reduction in industrial wastewater, and pressure flotation equipment. Further, the coagulation floc measuring device 5 can be applied to monitoring the sedimentation status of solid matter such as biological flocs, which is not limited to sludge, in the solid-liquid separation step of the sedimentation site or the like without the coagulation / mixing step.

<< Sludge treatment system and sludge treatment method (comparative example) and their problems >>
FIG. 5 is a flow chart showing an example of an operation method in a sludge treatment system which is a comparative example of the present invention. The operation flow shown in FIG. 5 is mainly executed by an operation operation by a field engineer. The sludge treatment system as a comparative example has a configuration that does not include, for example, a cohesive floc measuring device 5, a sludge concentrating trough 6, a flow meter SF3 and an SS densitometer SD2, a control device 11, and the like in FIG. In FIG. 5, the engineer first confirms the flow rate and concentration of the sludge A to be treated by using the flow meter SF1 and the concentration meter SD1, and sets the flow rate of the sludge A to be treated by using the sludge supply pump P1. (Step S501).

Next, based on the flow rate and concentration in step S501, the technician further reflects the past results and the like, the amount of the coagulant B added, the stirring strength of the stirring device 42 by the driving device M1, and the screw 73 by the driving device M2. The pressure of the back pressure plate 81 is determined manually or by the driving device (step S502). After operating the sludge treatment system in that state for a predetermined period of time, the technician visually confirms the formation state of the aggregated floc C and the SS of the dehydrator filtrate F (steps S503 and S504), and the dehydrated cake G The water content of the above is confirmed visually or by measurement using a moisture meter (step S505).

If any of the confirmation results in steps S503 to S505 is defective, the engineer returns to step S501 and / or step S502, changes the flow rate of the sludge A to be treated, and changes the flow rate of the coagulant B based on past results and the like. At least one of the change of the addition amount, the change of the stirring strength of the stirring device 42, the change of the rotation speed of the screw 73, and the change of the pressure of the back pressure plate 81 is carried out. On the other hand, if the confirmation results in steps S503 to S505 are good, the technician measures the hopper weight using the weight measuring device 102 and continues the operation of the sludge treatment system until the hopper weight reaches the weight reference value. (Step S506).

Further, while continuing the operation in step S506, the technician repeats the confirmation work of steps S503 to S505 as necessary. When the hopper weight reaches the weight reference value in step S506, the technician or the operator cleans the various devices using the automatic cleaning device incorporated in the various devices (step S507), and further, if necessary. Cleaning of various devices is performed manually (step 508).

As described above, the operation flow of FIG. 5 is performed by the personal judgment of a skilled technician who fully understands the situation of facilities and equipment. However, in recent years, due to social backgrounds such as the aging population and the shortage of the working population, the shortage of technicians has made it difficult to pass on the technology. Therefore, automation of the sludge treatment system is desired. In this case, for example, it is conceivable to use the techniques of Patent Documents 1 to 3 for local automation.

In the methods of Patent Documents 1 and 2, the water content of the dewatered sludge (dehydrated cake G) is measured by a moisture meter, and the sludge dewatering machine is controlled based on the measurement result. However, the values measured by the moisture meter may vary widely, and it is not always possible to control the water content below the water content reference value (for example, 80%). That is, the moisture meter is generally suitable for measuring a low water content, and it is often not possible to measure with high accuracy at a high water content. In this case, the control that reflects the measurement result of the moisture meter (pressure control of the back pressure plate or rotation speed control of the screw) is not always appropriate, so the validity of the control (or the measurement result) is appropriately determined by a technician. It may be necessary to confirm the validity).

Further, in the sludge dehydrator, it is desired to control not only the water content of the dehydrated cake G as shown in Patent Documents 1 and 2 but also the SS recovery rate. That is, for example, when an attempt is made to obtain a dehydrated cake G having a low water content in an insufficient state where the physical strength of the aggregated floc C is weak, control is performed in the direction of increasing the pressure of the back pressure plate 81. However, in this case, a situation may occur in which most of the sludge of the aggregated floc C is discharged from the screen 72 as the dehydrated filtrate H.

In the method of Patent Document 3, the aggregated state of the aggregated floc C is photographed with a camera, and the amount of the flocculant B added is adjusted based on the photographed data. However, when the aggregated flocs C are photographed with a camera, the aggregated flocs C may overlap each other, and sludge may adhere to the measuring portion due to the water containing the aggregated flocs containing a polymer or the like. For this reason, accurate evaluation may be difficult, and frequent maintenance may be required. That is, the intervention of a technician or the like may be required to some extent.

As described above, even if the techniques of Patent Documents 1 to 3 are used, a certain amount of personnel is still required in some processes, and there is a possibility that the problem of shortage of engineers and the problem of technology succession cannot be sufficiently alleviated. .. Further, when the method of Non-Patent Document 1 is used, the dehydration property of the dehydrated cake can be improved. However, while the dehydration property is improved, the amount of sludge adhering is increased. Therefore, for example, in the cleaning step performed as necessary after the treatment of one example is completed, the frequency of cleaning the screen 72 or the like using an automatic cleaning device may be increased. The amount of washing water may increase, and the amount of manual washing work may increase.

<< Sludge treatment method (embodiment) >>
2A and 2B are flow charts showing an example of detailed processing contents of the control device in the sludge treatment system of FIG. The control device 11 executes the flow of FIGS. 2A and 2B by, for example, program processing using a computer system. In FIG. 2A, the control device 11 issues an operation start instruction to the sludge supply pump P1 to be treated, the coagulant supply pump P2, the agitator 42, and the sludge dehydrator 7 (step S101).

Subsequently, the control device 11 measures the flow rate and the concentration of the sludge A to be treated using the flow meter SF1 and the densitometer SD1 (step S102). Next, the control device 11 calculates the amount of solid matter of sludge A to be treated based on the measured value in step S102, and determines the amount of coagulant B added according to the amount of solid matter (step S103). Specifically, the control device 11 controls the coagulant supply pump P2 so as to have the specified addition amount.

Regarding the amount of the coagulant B added to the amount of the solid matter of the sludge A to be treated, for example, the correspondence between the amount of the solid matter, the amount of the coagulant B added, and the size of the agglomerated floc C generated by the coagulation miscible device 4 is tested in advance. It is determined from the facts or past driving results. In the example of FIG. 1, the control device 11 controls the coagulant supply pump P2 while measuring the amount of the coagulant B added by the flow meter SF2. However, when the flow rate adjustment accuracy of the coagulant supply pump P2 is high, The flow meter SF2 is not always necessary.

The coagulation / mixing device 4 stirs the sludge A to be treated and the coagulant B with the stirrer 42 to generate the floc-generated water D containing the coagulation flocs C. The control device 11 measures the size of the aggregated flock C by using the aggregated flock measuring device 5 (step S104). Here, if the size of the agglomerated flocs C is too small, the agglomerated flocs C leak from the screen 72 of the sludge dewatering machine 7 in the dehydration step, and / or similarly leak from the screen 72 due to the back pressure on the back pressure plate 81. To do. In this case, it becomes difficult to perform a desired dehydration treatment in the dehydration step. On the other hand, if the amount of the flocculant B added is excessive, it is generally difficult to form agglomerates of the flocculant floc C, and the liquid itself becomes thickened, which leads to a significant increase in the cost of the flocculant.

Therefore, it is desirable that the size of the agglomerated floc C in the sewage sludge is controlled to be 5 to 100 mm, more preferably 10 to 50 mm. However, since the properties of sludge differ depending on each treatment facility and season, the size of the aggregated floc C is not necessarily limited to this range, and it is preferable to modify it based on the information of the past aggregated floc C. Here, in FIG. 5, a person periodically visually confirms the size of the agglomerated floc C in the agglomerating mixing tank 41, and by this periodic monitoring, the amount of the aggregating agent B added and the sludge to be treated A are measured. The amount of addition was adjusted sequentially.

On the other hand, in the embodiment, continuous monitoring is performed using the aggregation flock measuring device 5. As the cohesive flock measuring device 5, in the example of FIG. 1, an acoustic measuring method using an acoustic measuring device 51 or the like is used, but in some cases, an imaging method may be used as in the case of Patent Document 3. In the imaging method, a camera installed above the agglomerate mixing tank 41 or in water takes a picture of the agglomerated flock C, and the control device 11 measures the size of the agglomerated flock C by image processing the photographed image data. To do.

However, when the imaging method is used, as described in FIG. 5, there are cases where the aggregated flocs C overlap with each other, or sludge adheres to the measuring portion due to the water containing the aggregated flocs C containing the polymer. is there. Further, in the imaging method, imaging is performed on a limited narrow area, but the area is not always representative of all areas. As a result, in the imaging method, accurate measurement may be difficult and frequent maintenance may be required.

On the other hand, when the acoustic measurement method is used, since scanning can be performed in the depth direction, the overlap of the aggregated flocs C does not matter, and sludge does not particularly adhere to the measurement unit. Further, in the acoustic measurement method, the size of the aggregated floc C can be measured in all areas by controlling the scanning direction in three dimensions. Therefore, the imaging method may be used, but it is preferable to use the acoustic measurement method from the viewpoint of measurement accuracy and maintainability. As the cohesive flock measuring device 5 using the acoustic measurement method, for example, a commercially available fish finder or the like can be used. Therefore, it can be realized at low cost. The frequency of the sound wave transmitted by the acoustic transmitter / receiver 52 is preferably 200 kHz or more, preferably 400 kHz or more, in consideration of the size of the coagulated floc C to be recognized and the water depth of the coagulation mixing tank 41 (for example, about 1 m).

After measuring the size of the aggregated flock C in this way (step S104), the control device 11 determines whether or not the measured size of the aggregated flock C satisfies a predetermined reference value (specifically, whether or not it is within the reference range). Is determined (step S105). When the size is out of the reference range, the control device 11 adds 1 to 20%, preferably 3 to 10% of the current value of the coagulant B via the coagulant supply pump P2, as shown in FIG. 2B. Increase or decrease by a certain ratio (step S301). Specifically, the control device 11 reduces the addition amount when the size is large, and increases the addition amount when the size is small.

Then, the control device 11 measures the size of the aggregated floc C again after 0.1 to 20 minutes, preferably about 0.5 to 10 minutes (step S302). Here, when the size is still out of the reference range, the control device 11 supplies the sludge A to be treated via the sludge supply pump P1 to a ratio of 1 to 20%, preferably 3 to 10% of the current value. (Step S303). Specifically, the control device 11 increases the supply amount when the size is large, and decreases the supply amount when the size is small. Then, the control device 11 changes the rotation speed of the stirring device 41 via the driving device M1 so as to have a preset stirring strength according to the change in the supply amount of the sludge A to be treated (step S304). ..

In this state, the control device 11 re-evaluates the size of the aggregated floc C after 0.1 to 20 minutes, preferably about 0.5 to 10 minutes (step S305). If the size is still out of the reference range, the control device 11 returns to step S301 and changes the amount of the flocculant B added again. When the size of the aggregated floc C falls within the reference range through such a change, the control device 11 returns, for example, various conditions to the immediately preceding conditions and shifts to the process of step S102 (step S302, S305). Here, when the addition amount of the coagulant B is smaller than the initially set value and the supply amount of the sludge A to be treated is large, the operation may be continued without returning to the immediately preceding condition. As described above, by continuous monitoring using the control device 11, good aggregated floc C can be generated, which can contribute to stable operation of the sludge dewatering machine 7.

The floc-generated water D containing the agglomerated flocs C generated in the coagulation-mixing device 4 in this manner is transferred to the sludge dehydrator 7 via the sludge concentration trough 6. At this time, the sludge concentrating trough 6 separates water and sludge from the floc-generated water D by using the screen 62. Then, the sludge concentrating trough 6 supplies the concentrated floc C that becomes the sludge content to the sludge dehydrator 7, and the concentrated trough separation liquid E that becomes the water flows through the dehydration filtrate trough 74 of the sludge dehydrator 7 to dehydrate. Mix with filtrate H.

The coagulated floc C supplied to the sludge dewatering machine 7 is further drained by the screen 72 while being transferred by the screw 73 driven by the drive device M2. When the aggregated floc C is transferred to the back pressure plate 81, which is the discharge portion of the dehydrated cake G, the back pressure plate 81 performs consolidation and further removes water. On the other hand, the concentrated trough separation liquid E separated by the sludge concentrated trough 6 merges with the dehydrator filtrate F at the dehydration filtrate trough 74 and is usually returned to the water treatment system as the dehydration filtrate H.

Here, the control device 11 measures the flow rate and the SS concentration of the dehydrated filtrate H by using the flow meter SF3 and the SS concentration meter SD2 in step S106 of FIG. 2A. Then, the control device 11 uses the measured values of the flow meter SF3 and the SS densitometer SD2 and the measured values of the flow meter SF1 and the densitometer SD1 measured in step S102 to obtain the SS recovery rate r [%] and dehydration. The cake moisture content u [%] is calculated (steps S107 and S108). The SS recovery rate r is calculated by the formula (1), and the dehydrated cake water content u is calculated by the formula (2).
r = [1- (Qo × Co / Qi × Ci)] × 100… (1)
u = [(Ki × Qi-Ko × Qo)-(Qi × Ci-Qo × Co)] / (Ki × Qi-Ko × Qo) × 100… (2)

In the formulas (1) and (2), Qi [m ³ / h] is the flow rate of the sludge A to be treated by the flow meter SF1, and Qo [m ³ / h] is the flow rate of the dehydrated filtrate H by the flow meter SF3. The flow rate. Ci [t / m ³ ] is the concentration of sludge A to be treated by the densitometer SD1, and Co [t / m ³ ] is the SS concentration of the dehydrated filtrate H by the SS densitometer SD2. Ki indicates the specific gravity set in advance from the sludge A to be treated and Ko indicates the specific gravity preset from Ci and Co of the dehydration filtrate H, but when Ci is sufficiently low, Ki and Ko may be set to the specific gravity of 1 without any problem. .. “Qi × Ci” represents the amount of solid matter contained in the sludge A to be treated, and “Qo × Co” represents the amount of solid matter contained in the dehydration filtrate H. “Qi × Ci-Qo × Co” represents the amount of solid matter contained in the dehydrated cake G, and “Ki × Qi-Ko × Qo” represents the sum of the amount of water and the amount of solid matter contained in the dehydrated cake G.

Subsequently, in step S109, the control device 11 compares the SS recovery rate r calculated in step S107 with a predetermined recovery rate reference value (for example, 90 to 95%), and the SS recovery rate r is the recovery rate. If the reference value is not satisfied (for example, if it is less than 90 to 95%), the process proceeds to step S401 of FIG. 2B to change the operating conditions of the sludge dewatering machine 7. In step S401 of FIG. 2B, the control device 11 determines the clearance dimension (opening area) of the dehydrated cake discharge port. Then, the control device 11 sets the clearance dimension (opening area) of the dehydrated cake discharge port to the value determined in step S401 via the solenoid valve 84 while referring to the measured value of the displacement sensor 82 (step S402). (Step S403).

Further, the control device 11 changes the rotation speed of the screw 73 via the drive device M2, and then proceeds to step S102 of FIG. 2A (step S404). The situation in which the SS recovery rate r does not satisfy the recovery rate reference value is a situation in which sludge (for example, sludge of 10 to 5% or more) does not become the dehydrated cake G and flows out from the screen 72 as the dehydrated filtrate H. Therefore, the control device 11 performs the processes of steps S401 to S404 in order to suppress this outflow. At this time, the position of the back pressure plate 81 is controlled via the displacement sensor 82 from the viewpoint of suppressing the outflow of sludge with high accuracy, instead of the pressure of the back pressure plate 81 as in Patent Documents 1 and 2.

Here, the rotation speed of the screw 73 and the clearance dimension (opening area) of the dehydrated cake discharge port are initially set to initial values. Specifically, the control device 11 calculates the amount of solid matter based on the values of the flow meter SF1 and the densitometer SD1, and the rotation speed of the screw 73 and the clearance of the dehydrated cake discharge port, which are predetermined in a form corresponding to the amount of solid matter. Set the dimension (opening area) as the initial value. In this state, when the SS recovery rate r is less than the recovery rate reference value, the control device 11 changes the direction of increasing the clearance dimension (opening area) of the dehydrated cake discharge port and the direction of increasing the rotation speed of the screw 73. ..

Specifically, the clearance dimension (opening area) of the dehydrated cake discharge port is changed in the direction of widening by, for example, 1 to 50% of the current value, preferably 3 to 30%, and the rotation speed of the screw 73 is changed, for example. The value is changed so as to be 5 to 90%, preferably 10 to 75% of the current value. Then, the control device 11 continues the operation in the changed state for 5 to 120 minutes, preferably about 10 to 60 minutes. After that, when the SS recovery rate r is improved, the control device 11 may return the rotation speed of the screw 73 and the clearance dimension (opening area) of the dehydrated cake discharge port to the immediately preceding conditions, but the SS recovery rate r is Compared with the set value, if there is no problem, the operation may be continued without returning to the previous condition.

Subsequently, in step S110 of FIG. 2A, the control device 11 compares the dehydrated cake moisture content u calculated in step S108 with a predetermined moisture content reference value (for example, 70% or the like). Then, when the dehydrated cake moisture content u does not satisfy the moisture content reference value (for example, when it is 70% or more), the control device 11 proceeds to step S401 of FIG. 2B through the process of step S112 described later to dehydrate the sludge. Change the operating conditions of the machine 7. The method of changing the operating conditions at this time is partially different from the case of the SS recovery rate r described above.

In steps S401 to S404 of FIG. 2B, the control device 11 reduces the rotational speed of the screw 73 in the direction of narrowing the clearance dimension (opening area) of the dehydrated cake discharge port in order to reduce the water content u of the dehydrated cake. Control. Specifically, the clearance dimension (opening area) of the dehydrated cake discharge port is controlled in a direction of narrowing, for example, by a ratio of 1 to 50%, preferably 3 to 30% of the current value, and the rotation speed of the screw 73 is, for example, the present. The value is controlled to be lowered so as to be 5 to 90%, preferably 10 to 75% of the value. The control device 11 continues to operate for 1 to 120 minutes, preferably 3 to 60 minutes in the changed state, and when the dehydrated cake water content u improves thereafter, the clearance dimension (opening area) of the dehydrated cake discharge port ) And the rotation speed of the screw 73 may be returned to the immediately preceding conditions, but the dehydrated cake moisture content u may be compared with the set value, and if there is no problem, the operation may be continued without returning to the immediately preceding conditions.

On the other hand, when the water content u of the dehydrated cake is not improved, the control device 11 shifts from step S404 of FIG. 2B to step S401 of FIG. 2B again in step S110 via step S102 of FIG. 2A. Then, the control device 11 repeats the same process as described above in steps S401 to S404 of FIG. 2B. In steps S401 to S404 of FIG. 2B, the control device 11 changed both the rotation speed of the screw 73 and the clearance dimension (opening area) of the dehydrated cake discharge port, but in some cases, at least one of them. May be changed.

The dehydrated cake G dehydrated by the sludge dehydrator 7 is finally stored in the dehydrated cake storage hopper 10. In FIG. 2A, when both the SS recovery rate r and the dehydrated cake water content u satisfy the reference values (steps S109 and S110), the controller 11 stores a predetermined amount of the dehydrated cake G in the dehydrated cake storage hopper 10. The process of steps S102 to S110 is repeated until (step S111).

Specifically, the control device 11 measures the weight of the dehydrated cake G stored in the hopper 101 using the weight measuring device 102, and determines the measured weight of the dehydrated cake G and a predetermined weight reference value. Compare. Then, when the measured weight of the dehydrated cake G satisfies the weight reference value (when it becomes equal to or more than the weight reference value), the control device 11 proceeds to step S201. Further, even if the dehydrated cake water content u is not improved in step S112, the control device 11 proceeds to step S201 when a predetermined amount of the dehydrated cake G is stored in the dehydrated cake storage hopper 10.

In step S201, the control device 11 ends the dehydration step by issuing an operation stop instruction to the sludge supply pump P1 to be treated, the coagulant supply pump P2, and the agitator 42, and shifts to the automatic cleaning step of step S202. .. In step S202, the control device 11 issues a washing start command to the automatic washing device (not shown) mounted on the sludge dewatering machine 7 and / or the coagulation / mixing device 4. In response to this, the automatic cleaning device uses a cleaning nozzle to wash the portion to which each sludge adheres with water. After that, in step S203, the control device stops the sludge dehydrator 7 and ends a series of processes.

Here, in the sludge treatment system of FIG. 1, water repellent treatment by fluorine-based and / and silicone-based or vapor deposition is performed on the portion in direct contact with sludge. Therefore, the adhesion of sludge is reduced, and in step S202, the amount of water and the time required for cleaning are reduced, so that the operating cost can be reduced. Further, manual cleaning is not required. The inner surface of the coagulation mixing tank 41, the stirrer 42, the inner and outer surfaces of the screen 62 of the sludge concentration trough 6 and the screen 72 of the sludge dehydrator 7, the screw 73, and the dehydration filtrate trough 74 are located in direct contact with the sludge. , The back pressure plate 81 of the back pressure portion clearance adjusting device 8. Water repellent treatment is applied to at least a part, preferably all of these parts.

As described above, by using the sludge treatment system of FIG. 1 and the treatment flows of FIGS. 2A and 2B, automation of the sludge treatment system can be realized. In particular, in step S108 of FIG. 2A, the control device 11 calculates the dehydrated cake moisture content u based on the measured values of the flowmeter SF1 and the densitometer SD1 and the measured values of the flowmeter SF3 and the SS densitometer SD2. There is. Therefore, the highly accurate dehydrated cake moisture content u can be acquired in real time. That is, as described in FIG. 5, when the methods of Patent Documents 1 and 2 are used, confirmation work by an engineer or the like may be required, but the dehydrated cake contains water without going through such confirmation work. It becomes possible to automatically optimize the rate u. Further, by using the acoustic measurement method as the coagulation flock measuring device 5 and applying the water repellent treatment to the portion that comes into direct contact with the sludge, manpower required for maintenance, cleaning, etc. becomes unnecessary.

The measured values by the flow meters SF1 to SF3 and the densitometers SD1 and SD2, the measured values by the cohesive floc measuring device 5, the measured values by the displacement sensor 82, the control amount of the drive devices M1 and M2, etc. are recorded from the control device 11. It is sequentially stored on the medium. Then, the control device 11 or another information processing device determines further optimized operating conditions by an analysis tool including artificial intelligence (AI) based on various data stored in the data recording medium. .. Further, in some cases, the water content of the dehydrated cake G can be measured by using image sensing data from the shape at the time of discharge, the falling speed, the falling position, and the like.

<< Details of sludge concentration trough >>
FIG. 3 is a diagram showing a detailed arrangement example of the sludge concentrated trough in FIG. 1, and FIGS. 4 (a), 4 (b) and 4 (c) are detailed configurations of the sludge concentrated trough in FIG. It is a figure which shows an example. As shown in FIG. 3, the sludge concentration trough 6 is installed between the coagulation and mixing device 4 and the sludge dewatering machine 7. The screen 62 is installed at an angle θ of, for example, 20 to 80 °, preferably 30 to 70 °, with respect to the horizontal plane.

4 (a) is a plan view of the sludge concentrated trough 6, FIG. 4 (b) is a cross-sectional view between XX'in FIG. 4 (a), and FIG. 4 (c) is FIG. It is sectional drawing between YY'in (a). When the configuration of FIG. 4B is rotated clockwise and installed, the state of FIG. 3 is obtained. As shown in FIGS. 4 (b) and 4 (c), the sludge concentration trough 6 includes an upper bottom corresponding to the screen 62 (62a, 62b) and a lower bottom corresponding to the bottom plate 65. The screen 62 (62a, 62b) separates moisture from the aggregated floc C transferred on the screen, and the bottom plate 65 separates the concentrated trough separating liquid E separated and discharged by the screen into the sludge concentrated trough separating liquid piping. It is mixed with the dehydration filtrate H of the sludge dehydrator 7 via 61.

Further, as shown in FIGS. 4A and 4B, a water stop plate 64a and a water stop plate 64b are provided at the upstream end and the downstream end of the sludge concentration trough 6, respectively. Further, in the sludge concentration trough 6, side plates 63a and 63b are provided on both sides of the aggregated floc C with reference to the transfer direction, respectively, as shown in FIG. 4C. Here, the screen 62 includes a plurality of screen regions 62a and 62b (two in the examples of FIGS. 4A and 4B) having different mesh widths of the water discharge ports.

The screen region 62a is provided on the upstream side of the coagulation and mixing device 4, and the screen region 62b is provided on the downstream side of the sludge dehydrator 7. For example, the eye width of the screen area 62a on the upstream side is set to 0.5 to 10 mm, and the eye width of the screen area 62b on the downstream side is set to 0.1 to 5 mm. However, the number of divisions of the screen area is not limited to two, and may be three or more. That is, the screen 62 may be configured so that at least the mesh width of the screen region 62a on the coagulation / mixing device 4 side is larger than the mesh width of the screen region 62b on the sludge dehydrator 7 side.

Since the aggregated floc C having a relatively high strength passes on the upstream side, leakage of the aggregated floc C to the concentrated trough separation liquid pipe 61 is unlikely to occur even if the mesh width is increased. Therefore, on the upstream side, the dehydration efficiency can be improved by increasing the mesh width of the screen region 62a. On the downstream side, on the other hand, depending on the situation, aggregated flocs C having relatively low strength may pass through. Therefore, on the downstream side, by reducing the mesh width of the screen region 62b, the dehydration efficiency can be increased within a range in which the leakage of the aggregated floc C to the concentrated trough separation liquid pipe 61 can be sufficiently prevented.

The screen type used in the screen 62 is not particularly limited as long as it has a sludge concentration effect, such as a wedge wire screen and / or a punching metal screen and / or a bar screen, and / or a mesh. Further, the material and surface treatment of the contact portion of the aggregated floc C such as the screen 62, the side plates 63a and 63b and the water blocking plates 64a and 64b constituting the sludge concentration trough 6 are made of metal, coated on metal, or coated on metal. , Fluorine-based and / and silicone-based, water-repellent treated by vapor deposition, or resin. In particular, sludge adhering to the screen 62 causes clogging of the screen 62. Therefore, by using a water-repellent member, clogging can be suppressed, cleaning can be facilitated, and the frequency of cleaning can be adjusted. The amount of water can be reduced.

By using such a sludge concentrating trough 6, the sludge concentration of the coagulated floc C from the coagulation mixing device 4 is concentrated to, for example, 1.5 to 2 times or more, and the concentrated floc C is dewatered by the sludge dehydrator 7. Therefore, it is possible to contribute to the reduction of the water content of the dehydrated cake G. Here, for example, as shown in Patent Documents 1 and 2, a concentrator that rotates a disk with an external electric power is known. In comparison with this, when the sludge concentration trough 6 of the embodiment is used, since no external power is required, it is possible to realize power saving of the system and reduction of operating cost.

<< Main effects of the embodiment >>
As described above, by using the sludge treatment system and the sludge treatment method of the embodiment, the coagulation floc C is optimized by automatic control and the operating conditions of the sludge dewatering machine 7 are optimized based on the information obtained by highly accurate monitoring. Can be optimized. As a result, it becomes possible to alleviate the problem of shortage of technicians or technology succession. In addition, manual cleaning work after the completion of the dehydration process is not required, and ideally, a sludge treatment system that does not require human labor can be realized. This also makes it possible to increase the operating rate of the sludge treatment system.

In addition, it becomes possible to reduce the operating cost. For example, in the case of FIG. 5, the engineer generally sets a large amount of the coagulant B in order to surely generate the coagulated floc C. The flocculant B in particular causes an increase in cost. By using the method of the embodiment, the optimization of operation based on highly accurate monitoring eliminates the addition of excess flocculant B.

Furthermore, the amount of sludge carried out can be reduced. Specifically, the water content of the dehydrated cake G can be maintained at a sufficiently low value by performing various controls while monitoring the water content of the dehydrated cake G with high accuracy. As a result, the hopper 101 stores and carries out not the dehydrated cake G having a high water content (in other words, the dehydrated cake G containing a wasteful amount of water) but the dehydrated cake G having a sufficiently low water content. Therefore, the amount of sludge carried out can be reduced.

Although the invention made by the present inventor has been specifically described above based on the embodiment, the present invention is not limited to the embodiment and can be variously modified without departing from the gist thereof. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. .. Further, it is possible to add / delete / replace other configurations with respect to a part of the configurations of each embodiment.

4 Coagulation mixing device 5 Coagulation flock measurement device 6 Sludge concentration trough 7 Sludge dewatering machine 11 Control device 51 Sound measurement device 52 Sound transmitter / receiver 62 Screen 62a, 62b Screen area 65 Bottom plate 73 Screw 101 Hopper 102 Weight measurement device A Sludge to be treated B Coagulant C Coagulation Flock E Concentrated Trough Separation Solution G Dewatered Cake H Dehydrated Sulfate SD1, SD2 Concentrator SF1 to SF3 Flowmeter

Claims (10)

A coagulation and mixing device that generates coagulation flocs by supplying the sludge to be treated generated in the water treatment system and mixing the coagulant with the sludge to be treated.
A first flow meter and a first densitometer for measuring the flow rate and concentration of the sludge to be treated supplied to the coagulation and mixing apparatus, respectively.
A sludge dewatering machine that produces a dewatered cake with a reduced water content by separating and removing water from the aggregated flocs and discharges a dewatering filtrate corresponding to the water content.
A second flow meter and a second densitometer for measuring the flow rate and SS concentration of the dehydrated filtrate, respectively.
A control device that calculates the water content of the dehydrated cake based on the measured values of the first flow meter and the first densitometer and the measured values of the second flow meter and the second densitometer. When,
Sludge treatment system with. In the sludge treatment system according to claim 1,
Further, it has a sludge concentrated trough which is installed between the coagulation and mixing device and the sludge dewatering machine and generates concentrated coagulating flocs by increasing the sludge concentration of the coagulating flocs generated by the coagulation and mixing device.
The sludge concentrated trough
A screen that is the upper bottom and is installed at an angle of 30-70 ° to the horizontal plane to separate and drain moisture from the aggregated flocs that are transferred.
A bottom plate which is a lower bottom and mixes the concentrated trough separation liquid discharged by the screen with the dehydration filtrate of the sludge dehydrator.
Have,
Sludge treatment system. In the sludge treatment system according to claim 2.
The screen has a plurality of screen areas having different mesh widths of the moisture outlets.
The mesh width of the screen region on the coagulation / mixing device side is larger than the mesh width of the screen region on the sludge dehydrator side.
Sludge treatment system. In the sludge treatment system according to claim 2 or 3.
The screen is composed of a member that has been subjected to water-repellent treatment, oil-repellent treatment, or water-repellent oil-repellent treatment.
Sludge treatment system. In the sludge treatment system according to claim 1,
Further, it has an agglomeration flock measuring device for measuring the size of the agglomeration flocs generated by the agglomeration mixing device.
The cohesive flock measuring device is
An acoustic transmitter / receiver that transmits sound waves into the coagulation / mixing device and receives reflected waves from the coagulation flocs in the coagulation / mixing device.
An acoustic measuring device that performs signal processing on the reflected wave received by the acoustic transmitter / receiver, and
Have,
Sludge treatment system. A coagulation / mixing step in which the coagulation / mixing apparatus receives the supply of the sludge to be treated generated in the water treatment system, mixes the coagulant with the sludge to be treated, and stirs at a predetermined stirring strength to generate coagulation flocs.
A dewatering step in which a sludge dewatering machine separates and removes water from the aggregated flocs to generate a dewatered cake having a reduced water content, which is then stored in a hopper and discharges a dewatering filtrate corresponding to the water content.
It is a sludge treatment method that has
The dehydration step
A first step of measuring the flow rate and concentration of the sludge to be treated, and the flow rate and SS concentration of the dehydrated filtrate, which are supplied to the coagulation and mixing tank by a predetermined measuring instrument.
The control device calculates the moisture content of the dehydrated cake based on the measured value in the first step, compares the moisture content with a predetermined moisture content reference value, and the moisture content is the moisture content reference. The second step of changing the operating conditions of the sludge dewatering machine when the value is not satisfied, and
Have,
Sludge treatment method. In the sludge treatment method according to claim 6,
The coagulation and mixing step is
A third step in which the agglomeration flock measuring device measures the size of the agglomeration flock, and
The control device compares the size of the agglomerated flocs with a predetermined size reference value, and when the size of the agglomerated flocs does not satisfy the size reference value, the supply amount of the sludge to be treated and the aggregating agent. A fourth step of changing at least one of the supply amount and the stirring strength, and
Have,
Sludge treatment method. In the sludge treatment method according to claim 6 or 7.
In the dehydration step, the control device further calculates the SS recovery rate based on the measured value of the first step, compares the SS recovery rate with a predetermined recovery rate reference value, and performs the SS recovery rate. Has a fifth step of changing the operating conditions of the sludge dewatering machine when the recovery rate reference value is not satisfied.
Sludge treatment method. In the sludge treatment method according to claim 6 or 7.
The dehydration step further includes a sixth step in which the weight measuring device measures the weight of the dehydrated cake stored in the hopper.
In the sludge treatment method, the control device further compares the weight of the dehydrated cake measured in the sixth step with a predetermined weight reference value, and the weight of the dehydrated cake satisfies the weight reference value. In this case, it has a cleaning step of issuing a cleaning start command to the coagulation / mixing device or the automatic cleaning device mounted on the sludge dewatering machine.
Sludge treatment method. In the sludge treatment method according to claim 6 or 7.
The sludge dewatering machine is a screw press type device including a screw and a dewatered cake discharge port from which the dewatered cake is discharged.
When the operating conditions of the sludge dehydrator are changed in the second step, the control device changes at least one of the rotation speed of the screw and the opening area of the dehydrated cake discharge port.
Sludge treatment method.