Coagulation and sedimentation treatment apparatus and coagulation and sedimentation treatment method

Abstract

To provide a coagulation sedimentation treatment device and a coagulation sedimentation treatment method where solid matter separated in a coagulation sedimentation tank is properly drawn out and the occurrence of the overload of a rake and the water quality deterioration of treated water can be suppressed in the coagulation sedimentation treatment of raw water containing solid matter.SOLUTION: A coagulation sedimentation treatment device comprising a coagulation sedimentation tank, a measurement unit measuring the SS particle size distribution of raw water and a control unit controlling the drawn out of solid matter based on the measurement result of the measurement unit and a coagulation sedimentation treatment method using the device are provided. Time to accumulate (deposit) solid matter in the raw water in the coagulation sedimentation tank is predicted from the measurement result of the SS particle size distribution of the raw water. Control on the drawn out of the solid matter separated in the coagulation sedimentation tank is performed based on the time prediction. The occurrence of the overload of a rake and the water quality deterioration of treated water is suppressed and stable device operation can be performed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a coagulation sedimentation treatment apparatus and a coagulation sedimentation treatment method.

Background Art

[0002] Generally, as one of the means for wastewater treatment, solid-liquid separation treatment for removing impurities such as solids in wastewater is performed. As such solid-liquid separation treatment, there is a treatment using a coagulation sedimentation treatment apparatus that performs coagulation sedimentation to coagulate and sediment SS (Suspended Solid) which is an impurity by adding a coagulant to raw water (wastewater) and separating it. For example, there is known a coagulation sedimentation treatment apparatus provided with a sludge blanket type (sometimes called "floc zone type" or "floc blanket type") coagulation sedimentation tank that forms a blanket-like floc growth zone where flocs grow as the treated water to which a coagulant is added rises.

[0003] For example, Patent Document 1 describes a sludge blanket type coagulation sedimentation treatment apparatus in which a floc growth zone (sludge zone) is formed in a sedimentation tank. Further, Patent Document 1 describes a sludge blanket type coagulation sedimentation treatment apparatus in which a rake (sludge collecting member) and a distributor (raw water supply member) are integrated, and the rake and the distributor are rotated simultaneously to promote the generation and growth of flocs in the sedimentation tank, and concentrated sludge (settled flocs) is discharged out of the tank through a sludge discharge pipe from the center of the sedimentation tank.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the coagulation and sedimentation treatment apparatus described in Patent Document 1, it is stated that concentrated sludge (sedimented flocs) is discharged outside the tank through a sludge discharge pipe, but the timing of the discharge is not specifically described. Furthermore, in conventional coagulation and sedimentation treatment apparatuses such as the one described in Patent Document 1, it is common practice to discharge the concentrated sludge by manual operation based on the operator's judgment.

[0006] At this time, since the workers do not have an accurate understanding of the conditions inside the sedimentation tank, there is a risk of overloading the rake due to improper timing in withdrawing concentrated sludge from the tank. Furthermore, in particular, in sludge blanket type coagulation sedimentation tanks, there is a problem that sludge may be carried over from the floc growth zone into the treated water, potentially leading to deterioration of the treated water quality.

[0007] The object of the present invention is to provide a coagulation and sedimentation apparatus and a coagulation and sedimentation method that can appropriately extract the solids separated in the coagulation and sedimentation tank during the coagulation and sedimentation treatment of raw water containing solids, thereby suppressing overloading of the rake and deterioration of the water quality of the treated water. [Means for solving the problem]

[0008] As a result of diligent research into the above-mentioned problems, the inventors have discovered that in the coagulation and sedimentation treatment of raw water containing solids, by measuring the SS particle size distribution of the raw water and controlling the extraction of solids separated in the raw water within the coagulation and sedimentation tank based on these measurement results, it is possible to predict the state of solid separation (sedimentation) within the coagulation and sedimentation tank and appropriately extract the solids, thereby suppressing rake overload and deterioration of treated water quality, and thus completing the present invention. In other words, the present invention relates to the following coagulation and sedimentation treatment apparatus and coagulation and sedimentation treatment method.

[0009] The present invention, which solves the above problems, is characterized by comprising: a coagulation and sedimentation apparatus for separating solid matter contained in raw water by coagulation and sedimentation; a measuring unit for measuring the SS particle size distribution of the raw water; and a control unit that controls the extraction of solid matter separated in the coagulation and sedimentation apparatus based on the measurement results of the measuring unit. According to the coagulation and sedimentation apparatus of the present invention, by measuring the SS particle size distribution of the raw water, it is possible to predict the time it takes for solid matter in the raw water to be separated and accumulated (sedimented) in the coagulation and sedimentation tank. Then, by using the measurement results regarding the SS particle size distribution of the raw water to control the extraction of solid matter separated in the coagulation and sedimentation tank, it becomes possible to predict the state of solid matter separation (sedimentation) in the coagulation and sedimentation tank and appropriately extract the solid matter, thereby suppressing rake overload and deterioration of treated water quality, and enabling stable operation of the apparatus.

[0010] Furthermore, in one embodiment of the coagulation and sedimentation apparatus of the present invention, the coagulation and sedimentation tank comprises a sludge blanket section in which sludge is formed in a blanket shape to capture solid matter in the raw water, a concentration section provided below the sludge blanket section in which the sludge is concentrated, and a partition plate for separating the sludge blanket section and the concentration section, and the control unit is characterized in that it controls the extraction of solid matter from the sludge blanket section. According to these features, the coagulation and sedimentation tank comprises a sludge blanket section that captures solid matter in the raw water and a concentration section that concentrates the sludge that flows out from the sludge blanket section. Furthermore, by separating the sludge blanket section and the concentration section with a partition plate, it becomes possible to stabilize the treatment in the sludge blanket section. In addition, by controlling the extraction of solid matter from the sludge blanket section as a control unit, it is possible to appropriately discharge the solid matter accumulated on the partition plate separating the sludge blanket section and the concentration section, suppress the occurrence of overload of the rake provided in the sludge blanket section, and suppress the carryover of sludge from the sludge blanket section to the treated water. As a result, stable operation of the sludge blanket type coagulation and sedimentation apparatus becomes possible.

[0011] Furthermore, one embodiment of the coagulation and sedimentation apparatus of the present invention further comprises a rake for scraping up solid material and a load detection unit for detecting the load on the rake, and is characterized in that the detection result of the load detection unit is used as one of the control parameters related to the control unit. This feature allows for the use of measurement results related to the SS particle size distribution of raw water, as well as detection results related to rake load detection, as one of the control parameters in the control unit. This improves the accuracy of predictions regarding the separation (sedimentation) state of solids in the coagulation and sedimentation tank, enabling more appropriate extraction of solids and more stable operation of the system.

[0012] The present invention, which solves the above problems, is characterized by comprising: a coagulation and sedimentation step of separating solid matter contained in raw water by coagulation and sedimentation; a measurement step of measuring the SS particle size distribution of the raw water; and a control step of controlling the extraction of solid matter separated in the coagulation and sedimentation step based on the measurement results of the measurement step. According to the coagulation and sedimentation treatment method of the present invention, by measuring the SS particle size distribution of the raw water, it is possible to predict the time it takes for solid matter in the raw water to be separated and deposited during the coagulation and sedimentation process. Furthermore, by using the measurement results regarding the SS particle size distribution of the raw water to control the extraction of solid matter separated by the coagulation and sedimentation process, it becomes possible to predict the state of solid matter separation (sedimentation) during the coagulation and sedimentation process and to appropriately extract the solid matter, thereby suppressing rake overload and deterioration of treated water quality. [Effects of the Invention]

[0013] According to the present invention, in the coagulation and sedimentation treatment of raw water containing solids, it is possible to provide a coagulation and sedimentation treatment apparatus and a coagulation and sedimentation treatment method that can appropriately extract the solids separated in the coagulation and sedimentation tank, thereby suppressing overloading of the rake and deterioration of the water quality of the treated water. [Brief explanation of the drawing]

[0014] [Figure 1]This is a schematic diagram illustrating a coagulation and sedimentation apparatus according to a first embodiment of the present invention. [Figure 2] This is a schematic diagram illustrating the structure of a coagulation and sedimentation tank in a coagulation and sedimentation apparatus according to the first embodiment of the present invention. [Figure 3] This is a schematic diagram illustrating a coagulation and sedimentation apparatus according to a second embodiment of the present invention. [Figure 4] This is a schematic diagram illustrating a coagulation and sedimentation apparatus according to a third embodiment of the present invention. [Modes for carrying out the invention]

[0015] The present invention provides a coagulation and sedimentation apparatus and coagulation and sedimentation method that coagulates and settles solid matter contained in raw water, separating it into treated water and solid matter.

[0016] The raw water W0 to be treated in this invention may contain any solid matter to be separated, and the source (origin) and type of solid matter are not particularly limited. Examples of raw water W0 include factory wastewater, domestic wastewater, river water, and treated water from other water treatment facilities. In particular, the raw water W0 in this invention is preferably heavy in weight of solids. In this case, the processing speed in the coagulation and sedimentation treatment increases, and the effects of the coagulation and sedimentation treatment apparatus and coagulation and sedimentation treatment method of this invention are fully realized. Examples of such raw water W0 include wastewater from the steel industry. Wastewater from the steel industry is wastewater discharged from the manufacturing process and should contain coal-based SS (coke, coal, coal ore, etc.) and / or metallic SS (iron, iron oxide, etc.). Specific examples of such wastewater from the steel industry include dust collection water such as coke wet dust collection wastewater, secondary refining circulating water, direct steelmaking circulating water, direct rolling system circulating water, and other cooling water (circulating water) that comes into direct contact with steel products, as well as rainwater from raw material yards. Furthermore, the solid matter contained in raw water W0 includes not only the solid components originally present in raw water W0, but also flocs formed by adding a coagulant to raw water W0.

[0017] Hereinafter, embodiments of the flocculation sedimentation treatment apparatus and the flocculation sedimentation treatment method according to the present invention will be described in detail while referring to the drawings. Regarding the flocculation sedimentation treatment method of the present invention, it shall be replaced with the following description of the structure and operation of the flocculation sedimentation treatment apparatus. Also, the structure of the flocculation sedimentation treatment apparatus described in the embodiments is merely an example for explaining the flocculation sedimentation treatment apparatus according to the present invention and is not limited thereto.

[0018] [First Embodiment] FIG. 1 is a schematic explanatory diagram of a flocculation sedimentation treatment apparatus 100A according to a first embodiment of the present invention. The flocculation sedimentation treatment apparatus 100A according to the present embodiment has a flocculation sedimentation tank 1A called a so-called sludge blanket type. Generally, a sludge blanket type flocculation sedimentation tank forms a fluidized layer of sludge (flocculated flocs) by an upward water flow in the tank and passes solids (flocs) contained in raw water W0 through the fluidized layer. At this time, small flocs are captured by large flocs in the fluidized layer and grow larger, increasing the sedimentation rate. As a result, the raw water W0 introduced into the sludge blanket type flocculation sedimentation tank is separated into treated water W1 and concentrated flocs (sludge), and each is discharged outside the tank.

[0019] As shown in FIG. 1, the flocculation sedimentation treatment apparatus 100A according to the present embodiment includes a flocculation sedimentation tank 1A, an SS particle size distribution measurement unit 7 that measures the particle size distribution of SS in the raw water W0, and a control unit 8 that performs control related to the extraction of solids in the flocculation sedimentation tank 1A. Furthermore, as shown in Figure 1, the coagulation and sedimentation tank 1A in this embodiment includes a raw water introduction section 2 for introducing raw water W0 into the coagulation and sedimentation tank 1A from line L1, a sludge blanket section 3 formed in a blanket-like state where sludge for separating solid matter in the raw water W0 is suspended, a concentration section 4 where flocs that have coagulated by passing through the sludge blanket section 3 settle and concentrate below the sludge blanket section 3, a sludge discharge section 5 for discharging the flocs (sludge) that have settled and concentrated in the concentration section 4 to the outside of the system, and a coagulant addition section 6 for adding a coagulant to the raw water W0. A clear layer C, which is the supernatant, is formed above the sludge blanket section 3, and the cleared treated water W1 is discharged through line L2 located on the upper side of the coagulation and sedimentation tank 1. Note that a separate sludge treatment facility for treating the discharged flocs (sludge) may be provided at the sludge discharge section 5.

[0020] First, an example of the structure of the coagulation and sedimentation tank 1A in this embodiment will be described. Figure 2 is a schematic diagram of the coagulation and sedimentation tank 1A in the coagulation and sedimentation treatment apparatus 100A of the first embodiment of the present invention. Figure 2 shows the main structure of the coagulation and sedimentation tank 1A in this embodiment, with some parts omitted from the illustration. In the following description, "inside" refers to the side of the axis L, which is the center line of the coagulation and sedimentation tank 1A, and "outside" refers to the side that is spaced away from the axis L.

[0021] The coagulation and sedimentation tank 1A performs a coagulation and sedimentation process to separate solid matter contained in raw water W0 by coagulation and sedimentation. It comprises a bottomed, substantially cylindrical peripheral wall 11, and inside this peripheral wall 11, a side wall 12 and a partition plate 13. As shown in Figure 2, the partition plate 13 has an opening 13a in the center and is positioned horizontally to the cross-section of the peripheral wall 11. The side wall 12 is erected so as to protrude upward from a part of the outer edge of the partition plate 13. When this partition plate 13 is attached to the peripheral wall 11, the side wall 12 and the partition plate 13 become fixed members of the peripheral wall 11. As a result, a sludge blanket section 3, which will be described later, is formed inside the side wall 12. The partition plate 13 is also spaced a predetermined length above the bottom of the peripheral wall 11, separating the sludge blanket section 3 from the concentration section 4. A center shaft 14, which is rotationally driven by a motor M, is positioned on the axis L of the peripheral wall 11. The center shaft 14 is connected to the partition plate 13 by a sealing portion 15. The specific structure of the sealing portion 15 is not particularly limited, but examples include one with a labyrinth structure that is sealed by gas (air). The peripheral wall 11 is not limited to a cylindrical shape, but may be a rectangular tube shape. Alternatively, instead of the side wall 12, a bottomed cylinder provided concentrically with the peripheral wall 11 may be provided, and the bottom of this cylinder may serve as the partition plate 13.

[0022] The raw water introduction section 2 includes an introduction pipe 21 for introducing raw water W0 into the coagulation and sedimentation tank 1A, and a feed pipe 22 for supplying the raw water W0 introduced from the introduction pipe 21 to the inside of the side wall 12.

[0023] As shown in Figure 2, the inlet pipe 21 is inserted through the side wall of the peripheral wall 11 and protrudes to the outside of the tank, and is connected to the raw water W0 supply source via line L1. Furthermore, as shown in Figure 2, the feed pipe 22 is connected to the introduction pipe 21 so as to be able to pass water through it, and is installed on the outside of the center shaft 14 so as to surround the center shaft 14. In this embodiment, the coagulation and sedimentation treatment apparatus 100A has a common axis L for the peripheral wall 11, the center shaft 14, and the feed pipe 22.

[0024] The feed pipe 22 is divided vertically into an upper part 22a and a lower part 22b, and the upper and lower parts are connected by a seal section 23 (which has a labyrinth structure and is sealed with gas (air seal), etc.). An inlet pipe 21 is connected to the side of the upper part 22a of the feed pipe 22, and a distributor 24 is provided in the lower part 22b of the feed pipe 22. The distributor 24 is positioned at the lower part of the inside of the side wall 12 and has multiple raw water outlets 24a. As the center shaft 14 rotates, the lower part of the feed pipe 22 rotates, and at this time, the distributor 24 rotates with the raw water outlets 24a facing the partition plate 13. The upper end of the feed pipe 22 may be closed or open upwards. Furthermore, a rake 25 is provided at the bottom of the distributor 24, and its shape and arrangement are designed to scrape out the solid material accumulating on the partition plate 13 towards the outer periphery of the partition plate 13. This makes it possible to smoothly extract the solid material using the solid material extraction pipe 31, which will be described later.

[0025] The sludge blanket section 3 captures and coagulates SS (solid matter) in the raw water W0 supplied from the raw water introduction section 2 using sludge suspended in a blanket-like manner, separating it into coagulated flocs and treated water W1.

[0026] As shown in Figure 2, the sludge blanket section 3 refers to the inner region formed by the side wall 12 and the partition plate 13 within the coagulation and sedimentation tank 1. The sludge blanket section 3 also has a region where sludge forms in a blanket shape (hereinafter referred to as the "floc growth zone Z1"). In the floc growth zone Z1, a fluidized bed of coagulated flocs is formed by the rising water flow of raw water W0 that flows into the inside of the side wall 12 through the raw water introduction section 2.

[0027] Raw water W0 is uniformly ejected from the distributor 24 of the raw water inlet 2 towards the lower part of the side wall 12 (towards the partition plate 13). The flocs formed in the sludge blanket section 3 attempt to accumulate at the bottom of the sludge blanket section 3, but the further supply of raw water W0 causes a fluidized bed to form in the floc growth zone Z1. Small flocs contained in the raw water W0 come into contact with and are captured by previously formed flocs as they rise through the fluidized bed, causing the floc particle size within the sludge blanket section 3 to grow larger. In this way, suspended solids (SS) in the raw water W0 are separated within the floc growth zone Z1.

[0028] In this configuration, by making the distributor 24 rotatable, raw water W0 can be uniformly introduced into the sludge blanket section 3, and the solid material (sludge) accumulated on the partition plate 13 can be fluidized. This facilitates the formation and maintenance of the floc growth zone Z1 in the sludge blanket section 3.

[0029] Then, once the flocs in the sludge blanket section 3 have grown to a certain extent, they stop rising. Therefore, as shown in Figure 2, larger and heavier flocs continue to accumulate at the top of the sludge blanket section 3. The flocs F that have accumulated at the top of the sludge blanket section 3 overflow outwards (towards the peripheral wall 11) from the upper edge of the side wall 12 due to the fluidized bed created by the raw water W0.

[0030] Furthermore, as shown in Figure 2, the treated water that has passed through the sludge blanket section 3 rises due to the upward flow of the raw water W0, and a clarification layer C consisting of treated water W1 is formed above the sludge blanket section 3. The treated water W1 in the clarification layer C is discharged outside the tank from the top of the coagulation and sedimentation tank 1 via line L2.

[0031] In the floc growth zone Z1 within the sludge blanket section 3, a fluidized bed is formed by the raw water W0 supplied via the distributor 24. However, if there is variation in the particle size (SS particle size) of the solids contained in the raw water W0, some of the larger solid particles will accumulate on the partition plate 13. The continued accumulation of solids on the partition plate 13 may lead to an overload on the rake 25 or to sludge carryover from the fluidized bed in the sludge blanket section 3. Therefore, it is necessary to properly remove the solids accumulated in the sludge blanket section 3.

[0032] In this embodiment, the sludge blanket section 3 is provided with a solid material extraction pipe 31 that communicates with the partition plate 13 and passes through the peripheral wall 11, as shown in Figures 1 and 2. Solid material can be extracted from the sludge blanket section 3 via this solid material extraction pipe 31. The solid material extraction tube 31 only needs to be capable of extracting solid material from the sludge blanket section 3, and there are no particular limitations on where the solid material extraction tube 31 is placed. For example, as shown in Figures 1 and 2, instead of providing a solid material extraction tube 31 that communicates with the partition plate 13, a solid material extraction tube 31 that communicates (passes through) the lower end of the side wall 12 and the peripheral wall 11 can be provided.

[0033] Furthermore, the solid material extraction pipe 31 is equipped with an on-off valve 32. The opening and closing operation of this on-off valve 32 can be controlled by the control unit 8, which will be described later. This makes it possible to extract solid material from the sludge blanket section 3 at the appropriate timing. Furthermore, when extracting solid matter via the solid matter extraction pipe 31 and the on-off valve 32, a pump may be installed on the solid matter extraction pipe 31. However, as shown in Figure 1, the solid matter extraction pipe 31 and the sludge extraction pipe 51 (described later) are joined together, and the solid matter (sludge) is extracted using a pump P installed at the point of this merger. This makes it possible to perform operations related to the extraction of all solid matter separated in the coagulation and sedimentation tank 1A with a single pump, simplifying the extraction process and reducing the initial and running costs of the coagulation and sedimentation treatment device 100A.

[0034] The concentration section 4 is for concentrating the flocs F that have flowed out of the sludge blanket section 3. The concentration section 4 is partitioned by the aforementioned partition plate 13 and is located below the sludge blanket section 3, forming a floc concentration zone Z2 where the flocs F settle and are concentrated by passing between the side wall 12 and the peripheral wall 11.

[0035] As shown in Figure 2, the flocs F that flow out from the sludge blanket section 3 and enter the space between the side wall 12 and the peripheral wall 11 naturally settle toward the concentration section 4 because their specific gravity is greater than that of water. As a result, the flocs F that flow out from the floc growth zone Z1 do not flow back towards the sludge blanket section 3, and the treatment of the clarification layer C is stabilized. The concentrated flocs (sludge S) that settle and accumulate in the concentration section 4 are discharged from the sludge discharge section 5 located at the bottom of the coagulation and sedimentation tank 1A. The structure of the sludge discharge section 5 is not particularly limited as long as it can discharge the concentrated flocs (sludge S). For example, as shown in Figures 1 and 2, the sludge discharge section 5 may include a sludge extraction pipe 51 for transferring the concentrated flocs (sludge S) out of the system, an on / off valve 52 provided on the sludge extraction pipe 51, a recess 53 provided at the bottom of the coagulation and sedimentation tank 1A where the concentrated flocs are temporarily collected, and a pump P for extracting the concentrated flocs. Here, the opening and closing operation of the on-off valve 52 can be controlled by the control unit 8, which will be described later. This makes it possible to withdraw solid matter (sludge S) from the concentration unit 4 at the appropriate timing.

[0036] Furthermore, a sludge scraping means 41 is attached to the lower end of the center shaft 14, which extends through the partition plate 13 into the concentration section 4. This sludge scraping means 41 is provided to scrape the concentrated flocs that have settled in the concentration section 4 to the center of the bottom surface of the coagulation and sedimentation tank 1 and pull them out from the sludge discharge section 5. The sludge scraping means 41 only needs to be capable of scraping the concentrated flocs that have settled at the bottom of the coagulation and sedimentation tank 1A towards the sludge discharge section 5 (recess 53), and its specific structure is not particularly limited. Examples of the sludge scraping means 41 include a swivel shaft 42, a support rod 43, a rake 44, etc., as shown in Figure 2. Furthermore, the concentrated sludge scraper 41 attached to the lower end of the center shaft 14 is not particularly limited as long as it has a structure that rotates in conjunction with the rotation of the center shaft 14 and can scrape concentrated flocs to the center of the bottom surface of the coagulation and sedimentation tank 1 (the recess 53 of the sludge discharge section 5). For example, as shown in Figure 2, in addition to providing a plurality of rakes 44 via support rods 43 on a swivel shaft 42 that intersects the center shaft 14 perpendicularly, and in addition to providing scraping members (rakes) perpendicular to the center shaft 14, a scraping member having a curved surface may be provided on the center shaft 14 so as to form an S shape when viewed from above the tank.

[0037] The coagulant addition section 6 is for adding a coagulant to the raw water W0 to promote the formation of flocs of suspended solids (SS) in the raw water W0. The coagulant addition section 6 is not particularly limited as long as it can add a coagulant to the raw water W0. For example, Figure 1 illustrates a system in which a coagulant supply line 61 is provided on line L1 to supply the coagulant, but it is not limited to this. For example, a reaction tank may be provided upstream of the coagulation and sedimentation tank 1A, and the raw water W0 obtained by pre-mixing the raw water W0 from the supply source with the coagulant may be supplied to the introduction pipe 21.

[0038] The coagulant mixed with the raw water W0 is not particularly limited. Examples include inorganic coagulants and polymeric coagulants. The coagulant may consist of only an inorganic coagulant or only a polymeric coagulant, or a combination of both. When using both inorganic and polymeric coagulants, it is preferable to add the inorganic coagulant first, followed by the polymeric coagulant, to the raw water W0. This enables stable floc formation.

[0039] Specific examples of flocculants include, for instance, inorganic flocculants such as aluminum sulfate and PAC, which are Al-based inorganic flocculants, and iron-based inorganic flocculants such as polyferrous sulfate. Alternatively, pH adjusters such as alkalis like NaOH and Ca(OH)2 or acids like H2SO4 and HCl may be used, or crystals may be precipitated by adding Ca, Al, or Fe-based compounds, or by adding oxidizing or reducing agents. Furthermore, polymer flocculants include cationic polymer flocculants such as polyaminoalkyl methacrylate, polyethyleneimine, halide polydiallylammonium, chitosan, and urea-formaldehyde resin; anionic polymer flocculants such as sodium polyacrylate, partially hydrolyzed polyacrylamide, partially sulfomethylated polyacrylamide, and poly(2-acrylamide)-2-methylpropane sulfate; nonionic polymer flocculants such as polyacrylamide and polyethylene oxide; and amphoteric polymer flocculants such as copolymers of acrylamide, aminoalkyl methacrylate, and sodium acrylate.

[0040] The SS particle size distribution measurement unit 7 performs a measurement process to measure the particle size distribution of SS in the raw water W0, and is not particularly limited as long as it is capable of measuring the particle size distribution of SS in the raw water W0. As shown in Figures 1 and 2, the SS particle size distribution measurement unit 7 includes a mechanism for sampling a portion of the raw water W0 on the inlet pipe 21, and performs particle size distribution measurement on the sampled material. In this case, the means for performing particle size distribution measurement are not particularly limited, and known measurement methods and measuring devices can be used. Furthermore, the SS particle size distribution measurement unit 7 may be equipped with a measuring device capable of measuring particle size distribution on the introduction pipe 21 to perform online measurement (in-situ measurement). Examples include a particle size distribution measuring device using a laser, or a device capable of measuring particle size distribution based on image acquisition and image processing.

[0041] The SS particle size distribution measurement unit 7 in this embodiment is not limited to being installed on the introduction pipe 21, as shown in Figures 1 and 2. For example, the SS particle size distribution may be measured separately for the raw water W0 before it is introduced into the coagulation and sedimentation treatment device 100A (coagulation and sedimentation treatment tank 1A), and the measurement results may be used as control parameters in the control unit 8 described later. Furthermore, the raw water W0 to be measured by the SS particle size distribution measurement unit 7 may be raw water W0 after the addition of a coagulant, or raw water W0 before the addition of a coagulant, as shown in Figures 1 and 2.

[0042] Since the rate at which solid matter (SS) in the raw water W0 settles in the coagulation and sedimentation tank 1A also depends on the particle size distribution, by measuring the particle size distribution of SS in the raw water W0 at the raw water inlet 2 (inlet pipe 21), it is possible to estimate the time it takes for the solid matter separated in the coagulation and sedimentation tank 1A to accumulate in the tank. In particular, in the coagulation and sedimentation tank 1A of this embodiment, by measuring the particle size distribution of SS in the raw water W0, it is possible to estimate the time until solid matter (SS) accumulates at the bottom of the floc growth zone Z1 (on the partition plate 13) of the sludge blanket section 3. In other words, based on the measurement results of the SS particle size distribution measurement unit 7, it becomes possible to estimate the time until the allowable amount of solid matter accumulation in the sludge blanket unit 3 is reached. Here, the allowable amount of solid matter accumulation refers to the amount of solid matter separated and accumulated in the coagulation and sedimentation tank 1A that does not hinder the treatment in the coagulation and sedimentation tank 1A. More specifically, it is set to a value lower than the amount of solid matter accumulation that causes deterioration of the water quality of treated water W1 due to overload of the rake 25 or carryover. This can be set in advance based on past operating conditions and the experience of the workers, or it can be calculated based on various measurement values ​​related to the operation of the coagulation and sedimentation treatment device 100A. Based on the estimated time to reach the allowable accumulation limit of solid matter, solid matter is extracted from the sludge blanket section 3 via the solid matter extraction pipe 31, enabling extraction of solid matter at the appropriate timing and allowing for stable operation of the device.

[0043] The control unit 8 performs control processes related to the extraction of solids separated in the coagulation and sedimentation tank 1A based on the measurement results of the SS particle size distribution measurement unit 7. More specifically, it performs control related to the extraction of solids accumulated at the bottom of the sludge blanket unit 3 (on the partition plate 13) and the extraction of concentrated sludge accumulated in the concentration unit 4 via the sludge discharge unit 5, based on the time until the allowable amount of solids to be accumulated, which is calculated from the measurement results of the SS particle size distribution measurement unit 7.

[0044] The control unit 8, for example, as shown in Figure 1, is connected to the SS particle size distribution measurement unit 7 so that it can receive the measurement results, and is also controllably connected to the on-off valve 32 on the solid material extraction pipe 31 and the on-off valve 52 on the sludge extraction pipe 51. This makes it possible to extract solid material at the appropriate timing in locations where extraction of solid material is necessary. Furthermore, the control unit 8 may also be connected to the pump P on the sludge extraction pipe 51 in a controllable manner, and the amount of solid material extracted may be controlled by controlling the drive of the pump P.

[0045] The control unit 8 may control the opening and closing operations of the on-off valves 32 and 52 independently or in conjunction with each other. More specifically, by individually controlling the opening degree of the on-off valve 32 and the opening degree of the on-off valve 52, it is possible to simultaneously extract solid material from the sludge blanket section 3 and the concentrated flocs from the concentration section 4, or to link the opening and closing operations of the on-off valves 32 and 52 so that when one is open, the other is closed. In this embodiment, considering the frequency of solid material extraction and the efficiency of extraction, it is preferable that the control unit 8 links the opening and closing operations of the on-off valves 32 and 52 so that solid material is extracted from one of them.

[0046] While control by the control unit 8 may include manual operation by an operator, it is preferable to enable automatic control by using a computing device that executes programs necessary for a series of operations in the control unit 8, such as calculations based on the measurement results in the SS particle size distribution measurement unit 7, using a processor such as a CPU.

[0047] An example of control in the control unit 8 will be described. First, the SS particle size distribution measurement unit 7 measures the SS particle size distribution of the raw water W0, and based on these measurement results, the time until the allowable amount of solids to accumulate in the coagulation and sedimentation tank 1A is estimated. In particular, between the sludge blanket section 3 and the concentration section 4, the sludge blanket section 3 is more affected by the accumulation of solids, so it is preferable to estimate the time until the allowable amount of solids to accumulate in the sludge blanket section 3 is reached and use this as a control parameter. Next, based on this estimated time, control is performed regarding the opening and closing operation of the on-off valve 32. That is, before the time to reach the allowable amount of solid material accumulation is reached, the on-off valve 32 is opened, and the solid material scraped from the partition plate 13 towards the solid material extraction pipe 31 by the rake 25 is discharged through the solid material extraction pipe 31, thereby extracting solid material from the sludge blanket section 3. At this time, by closing the on-off valve 52 on the sludge extraction pipe 51 side, it becomes possible to efficiently proceed with the extraction of solid material through the solid material extraction pipe 31 by the pump P. During the operation of the coagulation and sedimentation treatment device 100A, the control unit 8 repeatedly extracts solid material from the sludge blanket section 3 at each estimated time interval. This makes it possible to continue operation without causing rake overload or deterioration of treated water quality.

[0048] In this embodiment, the structure for extracting the solid material separated in the coagulation and sedimentation tank 1A is not limited to that shown in Figure 1. For example, as shown in Figure 1, when the solid material extraction pipe 31 and the sludge extraction pipe 51 are joined, a switching valve is provided at the point where the solid material extraction pipe 31 and the sludge extraction pipe 51 join, instead of the on-off valves 32 and 52, and the control unit 8 can switch the flow path (solid material extraction pipe 31 and sludge extraction pipe 51) related to solid material extraction. Furthermore, in the extraction of solid material from the sludge blanket section 3, instead of the solid material extraction pipe 31, holes communicating with the outside of the sludge blanket section 3 and openable / closable windows covering these holes are provided in the side walls 12 and partition plates 13 of the sludge blanket section 3, and these windows are controlled by the control unit 8. In this case, the solid material extracted from the sludge blanket section 3 will settle in the concentration section 4 as concentrated flocs.

[0049] As described above, the coagulation and sedimentation treatment apparatus 100A and coagulation and sedimentation treatment method of this embodiment make it possible to predict the time it takes for solid matter in the raw water to be separated and accumulated (settle) in the coagulation and sedimentation tank by measuring the SS particle size distribution of the raw water. Then, by using the measurement results regarding the SS particle size distribution of the raw water to control the extraction of solid matter separated in the coagulation and sedimentation tank, it becomes possible to predict the state of solid matter separation (settling) in the coagulation and sedimentation tank and to appropriately extract the solid matter, thereby suppressing rake overload and deterioration of treated water quality and enabling stable operation of the apparatus.

[0050] Furthermore, the coagulation and sedimentation treatment apparatus 100A of this embodiment includes a sludge blanket section for capturing solid matter in the raw water and a concentration section for concentrating the sludge that flows out from the sludge blanket section as a coagulation and sedimentation tank. By further separating the sludge blanket section and the concentration section with a partition plate, it is possible to stabilize the treatment in the sludge blanket section. In addition, by controlling the extraction of solid matter from the sludge blanket section as a control unit, it is possible to appropriately discharge the solid matter accumulated on the partition plate separating the sludge blanket section and the concentration section, suppress the occurrence of overload of the rake provided in the sludge blanket section, and suppress the carryover of sludge from the sludge blanket section to the treated water. As a result, it is possible to perform stable operation of the sludge blanket type coagulation and sedimentation apparatus.

[0051] [Second Embodiment] Figure 3 is a schematic diagram illustrating the coagulation and sedimentation treatment apparatus 100B according to a second embodiment of the present invention. As shown in Figure 3, the coagulation and sedimentation apparatus 100B according to this embodiment further includes a load detection unit 9 that detects the load on the rake 25 and / or rake 44, compared to the coagulation and sedimentation apparatus 100A of the first embodiment, and uses the detection result of the load detection unit 9 as one of the control parameters of the control unit 8. Note that the components of the coagulation and sedimentation apparatus 100B in this embodiment that are the same as those of the coagulation and sedimentation apparatus 100A in the first embodiment will not be described.

[0052] The load detection unit 9 is for detecting the rotational load of rake 25 and / or rake 44. As solid matter accumulates in the sludge blanket section 3 and solid matter concentrates in the floc concentration zone Z2 in the concentration section 4, the amount of solid matter (sludge) accumulated near each rake (rake 25 and / or rake 44) increases, and the rotational load on each rake (rake 25 and / or rake 44) increases. Therefore, by using the detection results of the rotational load of the rakes by the load detection unit 9 in conjunction with the measurement results by the SS particle size distribution measurement unit 7, it is possible to improve the accuracy of predictions regarding the separation (sedimentation) state of solid matter in the coagulation sedimentation tank 1A.

[0053] The load detection unit 9 is installed at a location related to the rotational drive of each rake (rake 25 and / or rake 44) in the coagulation and sedimentation tank 30. For example, it may be installed at least one of the rake 25 and / or rake 44, the center shaft 14, or the motor M. Although Figure 3 shows the load detection unit 9 installed in relation to the motor M, it is not limited to this configuration.

[0054] The load detection unit 9 is not particularly limited as long as it can detect the rotational load of the rake. For example, it could be a unit that detects the rotational torque of each rake (rake 25 and / or rake 44) or the center shaft 14, or a unit that detects the current value supplied to the motor M. The type of instrument used as the load detection unit 9 is not particularly limited, but examples include torque sensors, load cells, and ammeters. Furthermore, the detection results output from the load detection unit 9 may include outputting the measured value as is, or outputting information indicating that a detection was made only when the value exceeds a predetermined value. In particular, it is preferable to output information as a detection result indicating that the rake is overloaded or is prone to overloading. This allows the control unit 8 to make control-related decisions quickly, and at the same time, enables prompt action to suppress or resolve the occurrence of rake overload or deterioration of treated water quality.

[0055] In this embodiment, the control unit 8, as shown in Figure 3, is connected to the load detection unit 9 in conjunction with the SS particle size distribution measurement unit 7 so as to be able to receive input. An example of control by the control unit 8 in this embodiment will be described. The SS particle size distribution measurement unit 7 measures the SS particle size distribution of the raw water W0, and based on these measurement results, the time until the allowable amount of solids to accumulate in the coagulation and sedimentation tank 1A (sludge blanket section 3) is estimated. At the same time, the load detection unit 9 detects the rotational load related to the rake (especially the rake 25). Next, based on this estimated time and load detection, control is performed for the opening and closing operation of the on-off valve 32. For example, if the load detection unit 9 determines that the rake 25 is not overloaded, the on-off valve 32 is opened before the time reaches the estimated allowable amount of solid matter accumulation based on the measurement results from the SS particle size distribution measurement unit 7. This allows the solid matter scraped from the partition plate 13 towards the solid matter extraction pipe 31 by the rake 25 to be discharged through the solid matter extraction pipe 31, thereby extracting solid matter from the sludge blanket section 3. In other words, in this case, by mainly using the measurement results from the SS particle size distribution measurement unit 7 for control, it becomes easy to continue operation in a way that prevents rake overload and deterioration of treated water quality. On the other hand, if the load detection unit 9 receives information from the control unit 8 indicating that the rake 25 is overloaded or is prone to overloading, the control unit 8 promptly opens the on-off valve 32 and extracts solid material from the sludge blanket section 3 via the solid material extraction pipe 31. In other words, in this case, the control based on the detection result from the load detection unit 9 is given priority over the control based on the measurement result from the SS particle size distribution measurement unit 7, making it possible to quickly take action to suppress or resolve rake overload and deterioration of treated water quality.

[0056] In this embodiment, by using the measurement results from the SS particle size distribution measurement unit 7, along with the detection results from the load detection unit 9, as control parameters in the control unit 8, it is possible to improve the accuracy of the determination of whether or not the accumulation of solids is affecting the processing in the coagulation and sedimentation tank 1A. Furthermore, since the detection by the load detection unit 9 can be easily performed continuously while the coagulation and sedimentation treatment device 100B is in operation, it is possible to grasp the state of solid separation (settling) in the coagulation and sedimentation tank 1A with greater accuracy.

[0057] As described above, the coagulation and sedimentation treatment apparatus 100B of this embodiment uses the measurement results related to the SS particle size distribution of the raw water, as well as the detection results related to the rake load detection, as one of the control parameters in the control unit. This improves the accuracy of predictions regarding the separation (settling) state of solids in the coagulation and sedimentation tank, making it possible to extract solids more appropriately and enabling more stable operation of the apparatus.

[0058] [Third Embodiment] Figure 4 is a schematic diagram illustrating the coagulation and sedimentation treatment apparatus 100C according to a third embodiment of the present invention. As shown in Figure 4, the coagulation and sedimentation treatment apparatus 100C according to this embodiment is equipped with a coagulation and sedimentation tank 1B having a mixing chamber 26, in place of the sludge blanket section 3 in the coagulation and sedimentation tank 1A of the first embodiment. Note that the components of the coagulation and sedimentation apparatus 100C in this embodiment that are the same as those of the coagulation and sedimentation apparatus 100A in the first embodiment will not be described.

[0059] In this embodiment, the coagulation and sedimentation tank 1B is equipped with a mixing chamber 26 that forms a flow path for the raw water W0, instead of the structure of the sludge blanket section 3 and the partition plate 13 in the coagulation and sedimentation tank 1A. The structure of the mixing chamber 26 in this embodiment is not particularly limited, and known structures and ancillary equipment can be provided. For example, the coagulant addition section 6 may be provided inside the mixing chamber 26 instead of on line L1, or a rotary mixer for mixing and stirring the raw water W0 and coagulant may be provided inside the mixing chamber 26.

[0060] In this embodiment, due to its structure, solid matter accumulates only in the concentration section 4 at the bottom of the coagulation and sedimentation tank 1B. Therefore, in the coagulation and sedimentation treatment apparatus 100C of this embodiment, the time until the allowable amount of solids to be stored in the concentration section 4 is estimated based on the measurement results of the SS particle size distribution measurement section 7, and based on this estimated time until the allowable amount of solids to be stored is reached, solids (sludge) are withdrawn from the concentration section 4 via the sludge withdrawal pipe 51, thereby enabling withdrawal of solids at an appropriate timing and enabling stable operation of the apparatus.

[0061] The control by the control unit 8 in the coagulation and sedimentation apparatus 100C of this embodiment corresponds to the control related to the extraction of concentrated sludge accumulated in the concentration section 4 via the sludge discharge section 5, as described above in the first embodiment, and includes the control of the opening and closing operation of the on-off valve 52 based on the measurement results of the SS particle size distribution measurement section 7. The details are the same as described above, so the explanation will be omitted.

[0062] Therefore, even in cases where the coagulation and sedimentation apparatus 100C in this embodiment has a coagulation and sedimentation tank 1B without a sludge blanket section 3, it becomes easy to continue operation in a way that prevents rake overload and deterioration of treated water quality by using the measurement results from the SS particle size distribution measurement section 7 to control the extraction of solid matter.

[0063] The embodiments described above are merely examples of coagulation-sedimentation apparatus and coagulation-sedimentation method. The coagulation-sedimentation apparatus and coagulation-sedimentation method according to the present invention are not limited to the embodiments described above, and the coagulation-sedimentation apparatus and coagulation-sedimentation method according to the embodiments described above may be modified without changing the essence of the invention.

[0064] For example, the coagulation and sedimentation apparatus and coagulation and sedimentation method of this embodiment may return the solid material (flocs) extracted from the sludge blanket section to the raw water inlet section via a means for pulverizing the solid material (such as stirring or ultrasonic irradiation). This makes it possible to repeatedly process the flocs extracted from the sludge blanket section, and by returning the pulverized flocs, it becomes possible to form good sludge (coagulated flocs) as seed crystals, thereby obtaining good treated water.

[0065] Furthermore, for example, the coagulation and sedimentation treatment apparatus of this embodiment may be equipped with a raw water supply control means in the inlet pipe for controlling the amount of raw water supplied (flow rate). The raw water supply control means is not particularly limited as long as it can control the amount of raw water supplied to the coagulation and sedimentation tank. For example, a flow control mechanism such as a pump for supplying raw water to the inlet pipe or a valve for controlling the flow rate in the inlet pipe may be provided, and a control unit for controlling the drive of the flow control mechanism may also be provided. This makes it possible to easily form and maintain the floc growth zone in the sludge blanket section. [Industrial applicability]

[0066] The coagulation and sedimentation apparatus and coagulation and sedimentation method of the present invention are suitably used in water treatment related to solid-liquid separation treatment for removing solids as impurities, among water treatments for raw water containing solids. [Explanation of symbols]

[0067] 100A, 100B, 100C Coagulation and sedimentation treatment apparatus, 1A, 1B Coagulation and sedimentation tank, 11 Peripheral wall, 12 Side wall, 13 Partition plate, 13a Opening, 14 Center shaft, 15 Seal section, 2 Raw water introduction section, 21 Introduction pipe, 22 Feed pipe, 22a Upper part, 22b Lower part, 23 Seal section, 24 Distributor, 24a Raw water discharge port, 25 Rake, 26 Mixing chamber, 3 Sludge blanket section, 31 Solid material extraction pipe, 32 On / off valve, 4 Concentration section, 41 Sludge scraping means, 42 Swivel shaft, 43 Support rod, 44 Rake, 5 Sludge discharge section, 51 Sludge extraction pipe, 52 On / off valve, 53 Recess, 6 Coagulant addition section, 61 Coagulant supply line, 7 SS particle size distribution measurement section, 8 Control section, 9 Load detection unit, C clarification layer, F floc, L axis, L1, L2 lines, M motor, P pump, S sludge, W0 raw water, W1 treated water, Z1 floc growth zone, Z2 floc concentration zone

Claims

1. A coagulation and sedimentation tank separates solid matter contained in raw water by coagulation and sedimentation, A measuring unit for measuring the SS particle size distribution of the raw water, The system includes a control unit that controls the extraction of the solids separated in the coagulation and sedimentation tank based on the measurement results of the measurement unit, The aforementioned coagulation and sedimentation tank includes a sludge blanket section in which sludge is formed in a blanket shape to capture solid matter in the raw water, A concentration section provided below the sludge blanket section, in which the sludge is concentrated, It comprises a partition plate that separates the sludge blanket section and the concentration section, The coagulation and sedimentation apparatus is characterized in that the control unit performs control related to the extraction of the solid matter from the sludge blanket section.

2. A rake for scraping up the aforementioned solid material, The system further includes a load detection unit for detecting the load on the rake, The coagulation and sedimentation apparatus according to claim 1, characterized in that the detection result of the load detection unit is used as one of the control parameters relating to the control unit.

3. A sludge blanket section in which sludge is formed in a blanket shape and captures solid matter in the raw water, A concentration section provided below the sludge blanket section, in which the sludge is concentrated, A coagulation and sedimentation treatment method using a coagulation and sedimentation apparatus comprising a partition plate that separates the sludge blanket section and the concentration section, A coagulation and sedimentation step in which solid matter contained in the raw water is separated by coagulation and sedimentation, A measurement step for measuring the SS particle size distribution of the raw water, A coagulation and sedimentation treatment method characterized by comprising a control step for controlling the extraction of the solid matter from the sludge blanket portion based on the measurement results of the measurement step.

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