Coagulation and sedimentation treatment apparatus and coagulation and sedimentation treatment method

Abstract

To provide a flocculation sedimentation treatment device and a flocculation sedimentation treatment method capable of implementing proper treatment in both sides of treatment cost and treatment performance without excessively adding an additive in the flocculation sedimentation treatment of water to be treated containing dissolved organic matter.SOLUTION: In the flocculation sedimentation treatment of water to be treated in a treatment tank, an adsorbent adsorbing an organic matter amount corresponding to a difference between first organic matter concentration contained in the water to be treated and second organic matter concentration required in a subsequent treatment tank is added to the water to be treated; the adsorbent has no possibility of excessive addition since the treatment can be performed after recognizing the required amount of the adsorbent in the flocculation sedimentation treatment; on the other hand, treatment on the reduction of dissolved organic matter can be necessarily and sufficiently performed; and thereby proper treatment can be implemented in both sides of treatment cost and treatment performance.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] Various treatment means related to wastewater treatment are known, and the treatment means are selected according to the component to be removed in the wastewater. For example, as one of the treatment means when impurities such as solids are included as the component to be removed in the wastewater, solid-liquid separation treatment can be mentioned. As such solid-liquid separation treatment, there is a treatment using a coagulation sedimentation treatment apparatus that performs coagulation sedimentation to coagulate and sediment suspension substances and the like (hereinafter also referred to as "SS") that are impurities by adding a coagulant to the wastewater. Further, as such a coagulation sedimentation treatment apparatus, for example, there is known a coagulation sedimentation treatment apparatus provided with a sludge blanket type (which may also be called a "floc zone type" or a "floc blanket type") coagulation sedimentation tank that forms a blanket-shaped 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 collection member) and a distributor (raw water supply member) are integrated, 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

[0005] Sludge blanket type coagulation and sedimentation treatment devices, such as those described in Patent Document 1, are widely used for treating water containing suspended solids (SS). Furthermore, Patent Document 1 does not specifically mention the type of water being treated.

[0006] On the other hand, when the water to be treated contains not only solid matter but also dissolved organic matter, it is known that coagulation and sedimentation treatment can be performed on such water, and the dissolved organic matter is adsorbed onto the coagulated flocs formed by the inorganic coagulant. However, with this method, it can be difficult to treat the dissolved organic matter to below the target level, and a challenge arises in that a large amount of inorganic coagulant must be added to achieve sufficient treatment. Furthermore, when performing coagulation and sedimentation treatment on water containing dissolved organic matter, it is also possible to add additives for treating dissolved organic matter in addition to inorganic coagulants. In this case as well, simply adding treatment additives without consideration can easily lead to excessive addition of these additives, causing the treatment of dissolved organic matter in the water to proceed more than necessary and unnecessarily increasing the cost of using the treatment additives.

[0007] The object of the present invention is to provide a coagulation and sedimentation apparatus and a coagulation and sedimentation method that can perform appropriate treatment in terms of both treatment cost and treatment performance in the coagulation and sedimentation treatment of water to be treated containing dissolved organic matter, without adding excessive additives. [Means for solving the problem]

[0008] As a result of diligent research into the above-mentioned problems, the inventors of the present invention have found that in a coagulation and sedimentation treatment apparatus, the amount of organic matter that needs to be reduced from the organic matter concentration contained in the water to be treated can be determined, and this amount of organic matter can be adsorbed by an adsorbent, thereby enabling appropriate treatment without adding excessive additives, 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 a coagulation and sedimentation treatment apparatus that performs coagulation and sedimentation treatment of water to be treated in a treatment tank, characterized in that an adsorbent adsorbs an amount of organic matter corresponding to the difference between the first organic matter concentration contained in the water to be treated and the second organic matter concentration required downstream of the treatment tank.

[0010] According to the coagulation and sedimentation apparatus of the present invention, when treating water containing dissolved organic matter through coagulation and sedimentation, an adsorbent can be used to adsorb and treat the dissolved organic matter in the water. Furthermore, by defining the concentration of organic matter in the water to be treated before treatment as the first organic matter concentration and the concentration of organic matter in the treated water after treatment as the second organic matter concentration, the adsorbent can adsorb an amount of organic matter equivalent to the difference between the first and second organic matter concentrations, thereby enabling treatment equivalent to the organic matter concentration to be treated in the coagulation and sedimentation process. This allows for precise control over the amount of adsorbent required in the coagulation and sedimentation process, eliminating the risk of excessive adsorption. At the same time, the treatment related to the reduction of dissolved organic matter can be carried out sufficiently. Therefore, it is possible to implement appropriate treatment in terms of both treatment cost and treatment performance.

[0011] Furthermore, one embodiment of the coagulation and sedimentation apparatus of the present invention is characterized in that the amount of adsorbent added is equivalent to the amount of organic matter adsorbed. This feature allows for the addition of an equivalent amount of adsorbent capable of adsorbing an amount of organic matter equivalent to the difference between the first and second organic matter concentrations. This enables treatment of only the amount of organic matter to be treated in the coagulation and sedimentation process. This allows for a more optimal amount of adsorbent to be added, making it possible to implement appropriate treatment in terms of both treatment cost and performance for water to be treated containing dissolved organic matter. In particular, it enables even more appropriate treatment from a cost perspective.

[0012] Furthermore, one embodiment of the coagulation and sedimentation apparatus of the present invention is characterized by mixing the adsorbent with the water to be treated in the upstream stage of the treatment tank and allowing it to remain there for the time required for the adsorption of organic matter. This feature allows for the adsorption of organic matter equivalent to the difference between the first and second organic matter concentrations in the water to be treated before it is introduced into the treatment tank. This makes it possible to separate the coagulation and sedimentation process from the adsorption process, ensuring the adsorption of a specific amount of organic matter. As a result, it becomes possible to implement appropriate treatment for water containing dissolved organic matter, both in terms of treatment cost and treatment performance. In particular, it becomes possible to perform even more appropriate treatment in terms of treatment performance.

[0013] Furthermore, one embodiment of the coagulation and sedimentation apparatus of the present invention is characterized in that the treatment tank is of the sludge blanket type. This feature allows for the use of a sludge blanket-type treatment tank, where sludge forms a blanket-like structure within the tank. This effectively reduces the size of the treatment tank and clarifies the treated water, thereby improving the treatment performance related to coagulation and sedimentation. Furthermore, it enables the effective separation of the adsorbent used for adsorbing dissolved organic matter from the treated water. As a result, it becomes possible to perform coagulation and sedimentation treatment of water containing dissolved organic matter in a more appropriate manner, considering both treatment cost and treatment performance.

[0014] Furthermore, one embodiment of the coagulation and sedimentation apparatus of the present invention is characterized in that the adsorbent is activated carbon. Based on these characteristics, using activated carbon as an adsorbent, which has excellent adsorption capacity for dissolved organic matter and is readily available, allows for appropriate treatment in terms of both treatment cost and treatment performance. Furthermore, using activated carbon as an adsorbent also has the effect of improving the adsorption capacity for dissolved organic matter.

[0015] The present invention, which solves the above problems, is a coagulation and sedimentation treatment method that performs coagulation and sedimentation treatment on water to be treated in a treatment tank, and is characterized by comprising an adsorption step in which an adsorbent adsorbs an amount of organic matter corresponding to the difference between a first organic matter concentration contained in the water to be treated and a second organic matter concentration required in the downstream stage of the treatment tank.

[0016] According to the coagulation and sedimentation treatment method of the present invention, when treating water containing dissolved organic matter through coagulation and sedimentation, an adsorbent can be used to adsorb and treat the dissolved organic matter in the water. Furthermore, by including an adsorption step in which the adsorbent adsorbs an amount of organic matter equivalent to the difference between the first organic matter concentration in the water to be treated and the second organic matter concentration in the treated water, the treatment corresponding to the organic matter concentration to be treated in the coagulation and sedimentation treatment can be performed. As a result, the amount of adsorbent required in the coagulation and sedimentation treatment can be determined and the treatment can be performed accordingly, eliminating the risk of adding an excessive amount of adsorbent in the adsorption step. At the same time, the necessary treatment related to the reduction of dissolved organic matter can be carried out. Therefore, it is possible to implement appropriate treatment from both the perspective of treatment cost and treatment performance.

[0017] The present invention, which solves the above problems, is a coagulation and sedimentation apparatus that performs coagulation and sedimentation treatment on water to be treated in a treatment tank, and is characterized by comprising a rotary distributor for introducing water to be treated, a sludge blanket section having a section in which sludge is formed in a blanket shape and to which water to be treated is introduced to separate solid matter in the water to be treated, and an adsorbent addition section for adding an adsorbent to the water to be treated.

[0018] According to the coagulation sedimentation treatment apparatus of the present invention, by providing a rotary distributor, the water to be treated containing solids can be evenly distributed in the treatment tank, and by providing a sludge blanket section, miniaturization of the treatment tank and clarification of the treated water can be effectively achieved, and the treatment performance related to coagulation sedimentation treatment can be enhanced. Further, by providing an adsorbent addition section, it becomes possible to treat the dissolved organic matter contained in the water to be treated. Furthermore, it becomes possible to effectively separate the adsorbent used for adsorbing the dissolved organic matter from the treated water. As a result, it becomes possible to perform appropriate treatment from both the viewpoints of treatment cost and treatment performance in the coagulation sedimentation treatment of the water to be treated containing dissolved organic matter.

Effects of the Invention

[0019] According to the present invention, there can be provided a coagulation sedimentation treatment apparatus and a coagulation sedimentation treatment method capable of performing appropriate treatment from both the viewpoints of treatment cost and treatment performance without performing excessive additive application in the coagulation sedimentation treatment of water to be treated containing dissolved organic matter.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic explanatory view showing the coagulation sedimentation treatment apparatus of the first embodiment of the present invention. [Figure 2] It is a schematic explanatory view showing the structure of the coagulation sedimentation tank in the coagulation sedimentation treatment apparatus of the first embodiment of the present invention. [Figure 3] It is a schematic explanatory view showing an example of the treatment process in the coagulation sedimentation treatment apparatus of the first embodiment of the present invention. [Figure 4] It is a schematic explanatory view showing the coagulation sedimentation treatment apparatus of the second embodiment of the present invention.

Modes for Carrying Out the Invention

[0021] The coagulation sedimentation treatment apparatus and the coagulation sedimentation treatment method of the present invention are used for the coagulation sedimentation treatment of water to be treated containing dissolved organic matter.

[0022] The water to be treated W in this invention is not particularly limited, as long as it contains dissolved organic matter to be treated. Specific examples of such water to be treated include, for example, wastewater such as factory wastewater and domestic wastewater, as well as water used in rivers and lakes (including dam lakes). The water to be treated W may also contain impurities other than dissolved organic matter (such as suspended solids). This allows the coagulation and sedimentation treatment apparatus of this invention to be fully effective. Furthermore, the following embodiments describe water to be treated W containing dissolved organic matter and suspended solids, but are not limited to this.

[0023] Hereinafter, embodiments of the coagulation and sedimentation apparatus and coagulation and sedimentation method according to the present invention will be described in detail with reference to the drawings. Note that the coagulation and sedimentation method of the present invention will be replaced by the following description of the structure and operation of the coagulation and sedimentation apparatus. Furthermore, the structure of the coagulation and sedimentation apparatus described in the embodiments is merely an example to illustrate the coagulation and sedimentation apparatus according to the present invention and is not limited thereto.

[0024] [First Embodiment] (Coagulation and sedimentation treatment device) Figure 1 is a schematic diagram illustrating the coagulation and sedimentation treatment apparatus 100A of the first embodiment of the present invention. The coagulation and sedimentation treatment apparatus 100A according to this embodiment has a coagulation and sedimentation tank known as a sludge blanket type as a treatment tank. Generally, a sludge blanket type coagulation and sedimentation tank forms a fluidized bed of sludge (coagulated flocs) in the tank by an upward water flow, and allows newly generated flocs to pass through the fluidized bed. At this time, small flocs are captured by larger flocs in the fluidized bed and become larger, and the settling velocity increases. As a result, the water to be treated W introduced into the sludge blanket type coagulation and sedimentation tank is separated into treated water W1 and concentrated flocs (sludge), and each is discharged outside the tank.

[0025] By equipping the coagulation and sedimentation treatment apparatus 100A of this embodiment with a sludge blanket type sedimentation treatment tank, it is possible to effectively miniaturize the treatment tank and clarify the treated water, thereby improving the treatment performance related to coagulation and sedimentation. Furthermore, it becomes possible to effectively separate the adsorbent used for adsorption of dissolved organic matter from the treated water. As a result, it becomes possible to perform appropriate treatment in terms of both treatment cost and treatment performance for the coagulation and sedimentation treatment of water to be treated that contains dissolved organic matter.

[0026] As shown in Figure 1, the coagulation and sedimentation treatment apparatus 100A of this embodiment includes a water to be treated introduction section 2 for introducing water to be treated W into the coagulation and sedimentation tank 1 from line L1, a sludge blanket section 3 formed in a blanket-like state where sludge is suspended for separating solid matter in the water to be treated W, a concentration section 4 in which flocs that have coagulated by passing through the sludge blanket section 3 settle and become concentrated below the sludge blanket section 3, and a coagulant addition section 5 for adding a coagulant to the water to be treated W. Here, the solid matter separated in the sludge blanket section 3 refers to SS and adsorbent A in the water to be treated W. 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 the treated water discharge section 6 located on the upper side of the coagulation and sedimentation tank 1. In addition, the flocs that have settled and been concentrated in the concentration section 4 are discharged from the center of the bottom of the coagulation and sedimentation tank 1 through the sludge discharge section 7. A separate sludge treatment facility for processing the discharged flocs may be provided at the sludge discharge section 7. Furthermore, the coagulation and sedimentation treatment apparatus 100A of this embodiment is equipped with an adsorbent addition unit 8 for adding adsorbent A to the water to be treated W.

[0027] First, the coagulation and sedimentation tank 1, which is a treatment tank in the coagulation and sedimentation treatment apparatus 100A of this embodiment, will be described in detail. In the coagulation and sedimentation tank 1 of this embodiment, mainly the adsorption treatment of dissolved organic matter in the water to be treated W by adsorbent A and the coagulation and sedimentation treatment of suspended solids (SS) in the water to be treated W are performed.

[0028] Figure 2 is a schematic diagram illustrating the coagulation and sedimentation tank 1 in the coagulation and sedimentation treatment apparatus 100A of the first embodiment of the present invention. The coagulation and sedimentation tank 1 comprises a bottomed cylindrical outer wall portion 11 and a cylindrical inner wall portion 12 that is smaller in diameter and height than the outer wall portion 11. As shown in Figure 2, the inner wall portion 12 is erected inside the outer wall portion 11, concentrically with the outer wall portion 11. A partition plate 13 having an opening 13a is provided on the bottom side of the inner wall portion 12. This forms a sludge blanket portion 3, which will be described later, inside the inner wall portion 12. The partition plate 13 is separated by a predetermined length above the bottom of the outer wall portion 11, separating the sludge blanket portion 3 from the concentration portion 4. A center shaft 14, which is rotationally driven by a motor 16, is positioned on the axis L of the outer wall portion 11 and the inner wall portion 12. The center shaft 14 is connected to the partition plate 13 by a rotary joint 15 such as a labyrinth structure. Note that the outer wall portion 11 and the inner wall portion 12 are not limited to a cylindrical shape, but may be rectangular. Alternatively, the inner wall portion 12 may be in the shape of a bottomed cylinder, and the bottom of the inner wall portion 12 may be a partition plate 13.

[0029] The treated water introduction section 2 includes an introduction pipe 21 for introducing the treated water W into the coagulation and sedimentation tank 1, and a feed pipe 22 for supplying the treated water W introduced from the introduction pipe 21 into the inner wall section 12.

[0030] As shown in Figure 2, the inlet pipe 21 is inserted through the side wall of the outer wall portion 11 and protrudes to the outside of the tank, and is connected to the supply source of the water to be treated W 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 of the coagulation and sedimentation apparatus, the axes of the outer wall portion 11, the inner wall portion 12, the center shaft 14, and the feed pipe 22 all share a common axis L.

[0031] 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 rotary joint 23 such as a labyrinth structure. 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 bottom of the inner wall 12 and has multiple treated water discharge ports 24a formed therein. 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 treated water discharge ports 24a facing the bottom side (partition plate 13 side) of the inner wall 12. The upper end of the feed pipe 22 may be closed or open upwards.

[0032] The sludge blanket section 3 captures and coagulates suspended solids (SS) in the water to be treated W supplied from the water to be treated introduction section 2 using sludge suspended in a blanket-like manner, separating them into coagulated flocs and treated water W1. At the same time, it also separates the adsorbent A from the water to be treated W.

[0033] As shown in Figure 2, the sludge blanket section 3 refers to the inner region formed by the cylindrical inner wall section 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 the treated water W that flows into the inside of the inner wall section 12 through the treated water introduction section 2.

[0034] The water to be treated W is uniformly ejected from the distributor 24 of the water to be treated introduction section 2 toward the lower part of the inner wall section 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 water to be treated W causes a fluidized bed to form in the floc growth zone Z1. Small flocs contained in the treated water W 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, SS in the treated water W is separated within the floc growth zone Z1.

[0035] In this case, by making the distributor 24 rotatable, the water to be treated W can be introduced evenly into the sludge blanket section 3, and the sludge accumulated on the partition plate 13 can be fluidized. This makes it possible to easily form and maintain the floc growth zone Z1 in the sludge blanket section 3.

[0036] Then, once the flocs in the sludge blanket section 3 have grown to a certain size, 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 that have accumulated at the top of the sludge blanket section 3 are overflowed from the upper edge of the inner wall section 12 to the outer wall section 11 by the fluidized bed created by the treated water W.

[0037] 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 treated water W, and a clarification layer C consisting of the 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 via the treated water discharge section 6 provided at the top of the coagulation and sedimentation tank 1.

[0038] The concentration section 4 is for concentrating the flocs F that have flowed out from 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. The flocs F settle between the inner wall section 12 and the outer wall section 11, forming a floc concentration zone Z2 where they are concentrated as concentrated sludge.

[0039] As shown in Figure 2, the flocs F that flow out from the sludge blanket section 3 and enter the space between the inner wall section 12 and the outer wall section 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. In addition, the presence of a partition plate 13 in the sludge blanket section 3 prevents concentrated sludge from mixing from the floc concentration zone Z2 into the floc growth zone Z1.

[0040] The concentrated flocs (sludge) that settle and accumulate in the concentration section 4 are discharged from the sludge discharge section 7 located at the bottom of the coagulation and sedimentation tank 1. The structure of the sludge discharge section 7 is not particularly limited as long as it can discharge the concentrated flocs. For example, as shown in Figure 1, the sludge discharge section 7 may be equipped with a pump P and a line L2 for extracting the concentrated flocs.

[0041] Alternatively, a concentrated sludge scraper 41 may be attached to the lower end of a center shaft 14 that extends through the partition plate 13 into the concentrated section 4. This concentrated sludge scraper 41 is provided to scrape the concentrated flocs that have settled in the concentrated section 4 to the center of the bottom of the coagulation and sedimentation tank 1 and recover them from the sludge discharge section 7. 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. For example, as shown in Figure 2, in addition to providing a scraping member perpendicular to the center shaft 14, a plurality of scraping members (rakes) may be provided on a support that intersects perpendicularly with the center shaft 14, or a curved scraping member may be provided on the center shaft 14 so as to form an S shape when viewed from above the tank.

[0042] The coagulant addition section 5 is for adding a coagulant to the water to be treated W and promoting the formation of SS flocs in the water to be treated W. The coagulant addition unit 5 is not particularly limited as long as it can add a coagulant to the water to be treated W. For example, Figure 1 illustrates a system in which a coagulant supply line 51 is provided on line L1 to supply the coagulant, but it is not limited to this. For example, a mixing tank may be provided upstream of the coagulation and sedimentation tank 1, and the water to be treated W, which has been pre-mixed with the coagulant, may be supplied to the introduction pipe 21.

[0043] The flocculant mixed with the treated water W is not particularly limited. Examples include inorganic flocculants and polymer flocculants. The flocculant may be an inorganic flocculant or a polymer flocculant alone, or an inorganic flocculant and a polymer flocculant may be used in combination. When using an inorganic flocculant and a polymer flocculant in combination, it is preferable to add the inorganic flocculant and then the polymer flocculant to the treated water W in that order. This enables stable floc formation.

[0044] 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.

[0045] Furthermore, the coagulation and sedimentation treatment apparatus 100A of this embodiment is equipped with an adsorbent addition unit 8 for adding adsorbent A to the water to be treated W in the coagulation and sedimentation tank 1. This makes it possible to treat dissolved organic matter in the water to be treated W.

[0046] The adsorbent addition section 8 is for adding adsorbent A to the water to be treated W and adsorbing dissolved organic matter in the water to be treated W. The adsorbent addition unit 8 is not particularly limited as long as it can add the adsorbent A to the water to be treated W. For example, as shown in Figure 1, an adsorbent supply line 81 for supplying the adsorbent A is provided on line L1.

[0047] Furthermore, the adsorbent addition section 8 may be located either upstream or downstream of the coagulant addition section 5, or the coagulant addition section 5 and the adsorbent addition section 8 may be combined into one unit. In order to improve the contact efficiency between the dissolved organic matter in the treated water W and the adsorbent A, it is preferable to place the adsorbent addition section 8 upstream of the coagulant addition section 5. This makes it possible to more reliably adsorb dissolved organic matter by the adsorbent A.

[0048] The adsorbent A added to the water to be treated W is not particularly limited as long as it can adsorb dissolved organic matter in the water to be treated W, and known adsorbents can be used. Furthermore, the adsorbent A may be one on which dissolved organic matter is adsorbed only on the surface of the adsorbent, but from the viewpoint of adsorption capacity for dissolved organic matter, it is preferable to use an adsorbent with a porous structure. Specific examples of adsorbent A include activated carbon and clays such as bentonite. In particular, it is preferable to use activated carbon as adsorbent A in this embodiment because it has excellent adsorption capacity for dissolved organic matter and is readily available.

[0049] Adsorbent A is selected according to its adsorption capacity for dissolved organic matter (the amount of dissolved organic matter it can adsorb), as described later, and there are no particular limitations on the structure, size, or pore structure of adsorbent A itself. For example, the structure and size of the adsorbent may be selected so as to suppress blockage in the treated water introduction section 2 (such as the introduction pipe 21 or distributor 24) when the treated water W to which adsorbent A has been added is supplied into the coagulation and sedimentation tank 1. Furthermore, a structure and size may be selected such that the adsorbent A remains within the sludge blanket section 3. For example, adsorbent A may be made of a molded body. In this case, the adsorbent A remains within the sludge blanket section 3, thereby ensuring sufficient time for the adsorption process. Alternatively, a structure and size may be selected that allows the adsorbent A to flow from the sludge blanket section 3 to the concentration section 4. For example, adsorbent A may be made of powder. In this case, adsorbent A can be discharged from the sludge discharge section 7 together with the concentrated flocs accumulated in the concentration section 4 and can be easily recovered as used adsorbent A. This eliminates the need for replacement of adsorbent A and enables continuous processing.

[0050] (Treatment of water to be treated using a coagulation and sedimentation treatment system) This section describes a case in which the coagulation and sedimentation treatment apparatus 100A of this embodiment is used to treat water W containing dissolved organic matter and suspended solids. Figure 3 is a schematic diagram illustrating the treatment process of the water to be treated W using the coagulation and sedimentation treatment apparatus 100A of this embodiment. Note that the configuration of the coagulant addition section 5 is omitted in Figure 3.

[0051] The treated water W, containing dissolved organic matter and suspended solids (SS), is mixed with adsorbent A added by the adsorbent addition unit 8 and supplied to the coagulation and sedimentation tank 1 via the treated water introduction unit 2. Inside the coagulation and sedimentation tank 1, the coagulation and sedimentation of SS in the treated water W proceeds, along with the adsorption of dissolved organic matter by adsorbent A. After the SS and adsorbent A in the treated water W have settled and separated, and the dissolved organic matter content has decreased, the treated water W1 is discharged from the treated water discharge unit 6.

[0052] At this time, as shown in Figure 3, the dissolved organic matter concentration in the treated water W before it is supplied into the coagulation and sedimentation tank 1 (upstream of the adsorbent addition section 8) is defined as C1, and the dissolved organic matter concentration required downstream of the coagulation and sedimentation tank 1 (treatment tank) is defined as C2. C1 is referred to as the first organic matter concentration, and C2 as the second organic matter concentration. Here, the second organic matter concentration C2 corresponds to the dissolved organic matter concentration in the treated water W1 discharged from the treated water discharge section 6.

[0053] The first organic matter concentration C1 can be a measured value obtained by measuring the dissolved organic matter concentration in the treated water W before treatment, or a predicted value predicted from the source of the treated water W.

[0054] The second organic matter concentration C2 can be determined based on the dissolved organic matter concentration required for the water quality when treated water W1 is directly discharged, or based on the dissolved organic matter concentration required when treated water W1 is supplied to another water treatment facility. In other words, the second organic matter concentration C2 is not zero, but represents a predetermined value.

[0055] The difference C3 between the first organic matter concentration C1 and the second organic matter concentration C2 is calculated. At this time, the difference C3 corresponds to the organic matter concentration to be treated in the coagulation and sedimentation treatment device 100A. Furthermore, the difference C3 is converted to the amount of organic matter M from the supply amount of water to be treated W, etc. By adsorbing this amount of organic matter M with adsorbent A, it becomes possible to perform treatment corresponding to the organic matter concentration to be treated in the coagulation and sedimentation treatment device 100A. In other words, the amount of adsorbent A to be added from the adsorbent addition unit 8 is determined by calculating the amount that can adsorb the amount of organic matter M. This makes it possible to perform appropriate treatment in terms of both treatment cost and treatment performance without adding excessive adsorbent.

[0056] The specific means for calculating the amount of adsorbent A to adsorb organic matter M is not particularly limited. An example of the means for calculating the amount of adsorbent A to be added is described below. First, the water quality of the water to be treated W is measured before treatment to obtain data on the dissolved organic matter concentration (first organic matter concentration C1) in the water to be treated W. Furthermore, a value is set to satisfy the water quality standard for discharge, which is necessary for the subsequent stage of the treatment tank (second organic matter concentration C2). For example, a value equivalent to 50% of the environmental standard can be set as the second organic matter concentration C2. From this, the difference C3 is calculated. This allows us to determine the organic matter concentration that should be treated in the treatment tank in order to perform necessary and sufficient treatment without excessive treatment. Finally, the amount of organic matter M is calculated from the value related to the supply amount of water to be treated W to the treatment tank (coagulation and sedimentation tank 1). On the other hand, the type of adsorbent A that adsorbs dissolved organic matter is selected based on the water quality of the treated water W (especially the type of dissolved organic matter and pH value). Methods for selecting adsorbent A include selecting it based on its physical properties such as pore size and surface charge, or based on data from past treatment results. Then, a batch test is conducted using the treated water W and the selected adsorbent A to determine the amount of adsorbent A adsorbed over a certain period of time, thereby determining the adsorption capacity of adsorbent A per unit amount (the amount of dissolved organic matter that can be adsorbed). Based on the results of this batch test, the amount of adsorbent A that can adsorb the amount of organic matter M obtained from the difference C3 between the first organic matter concentration C1 and the second organic matter concentration C2 is calculated, and this value is used to determine the amount of adsorbent A to be added from the adsorbent addition section 8. At this time, the amount of adsorbent A to be added may be determined to be a value that is greater than the amount of adsorbent A that can adsorb the amount of organic matter M, but it is preferable to use the equivalent amount for adsorption of organic matter M. This makes it possible to optimize the amount of adsorbent A to be added, and it becomes possible to perform a more appropriate treatment, especially in terms of treatment cost, for the coagulation and sedimentation treatment of water to be treated that contains dissolved organic matter.

[0057] Another example of a means for calculating the amount of adsorbent A to be added is to automate the process of selecting adsorbent A and calculating the amount to be added. For example, measurement data related to the water quality of the water to be treated W is acquired in real time, and based on this measurement data, the difference C3 and the amount of organic matter M are automatically calculated, and according to this calculation result, the necessary amount of adsorbent A is automatically selected and added, and the selected and calculated amount of adsorbent A is added from the adsorbent addition unit 8. At this time, a database of suitable types and adsorption capacities of adsorbent A for each water quality of the water to be treated W is created based on past treatment results, and this database is used when selecting adsorbent A and calculating the amount to be added, thereby improving the accuracy of the automation of the process of selecting adsorbent A and calculating the amount to be added.

[0058] As described above, the coagulation and sedimentation treatment apparatus 100A of this embodiment can treat water containing dissolved organic matter by adsorbing the dissolved organic matter in the water using an adsorbent during coagulation and sedimentation treatment. Furthermore, in the coagulation and sedimentation treatment apparatus 100A of this embodiment, the adsorbent adsorbs an amount of organic matter equivalent to the difference between the first organic matter concentration, which is the organic matter concentration in the water to be treated before treatment, and the second organic matter concentration, which is the organic matter concentration in the treated water after treatment, thereby enabling treatment equivalent to the organic matter concentration that needs to be treated in the coagulation and sedimentation treatment. This makes it possible to determine the amount of adsorbent required in the coagulation and sedimentation treatment and perform the treatment accordingly, thus eliminating the risk of adding an excessive amount of adsorbent. On the other hand, the treatment related to the reduction of dissolved organic matter can be carried out sufficiently. Therefore, it is possible to implement appropriate treatment in terms of both treatment cost and treatment performance.

[0059] Furthermore, by using a sludge blanket type as the treatment tank in this embodiment, the coagulation and sedimentation treatment apparatus 100A can effectively reduce the size of the treatment tank and clarify the treated water, thereby improving the treatment performance related to coagulation and sedimentation. In addition, it becomes possible to effectively separate the adsorbent used for adsorption of dissolved organic matter from the treated water. As a result, it becomes possible to perform a more appropriate treatment in terms of both treatment cost and treatment performance for water to be treated that contains dissolved organic matter.

[0060] [Second Embodiment] Figure 4 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 4, the coagulation and sedimentation treatment apparatus 100B according to this embodiment is equipped with a reaction tank T in front of the coagulation and sedimentation tank 1 in the first embodiment, and mixes the water to be treated W and the adsorbent A in the reaction tank T, thereby adsorbing dissolved organic matter onto the adsorbent A. In this embodiment, the structure of the coagulation and sedimentation treatment apparatus 100B is the same as that of the coagulation and sedimentation tank 1, and therefore its description is omitted. Also, in Figure 4, the configuration of the coagulant addition unit 5 is omitted. The coagulant addition unit 5 in this embodiment only needs to be capable of adding a coagulant to the water to be treated W supplied to the coagulation and sedimentation tank 1, and can have the same configuration as in the first embodiment. For example, a coagulant supply line may be provided at a location corresponding to the downstream side of the adsorbent addition unit 8 (on line L4) to add the coagulant to the water to be treated W.

[0061] As shown in Figure 4, the coagulation and sedimentation treatment apparatus 100B of this embodiment is equipped with a reaction tank T in front of the coagulation and sedimentation tank 1. The reaction tank T includes a line L3 for introducing the water to be treated W, an adsorbent addition section 8 (adsorbent supply line 82) for adding adsorbent A to the water to be treated W, and a line L4 for supplying the water to be treated mixed with adsorbent A to the coagulation and sedimentation tank 1. Line L4 is also connected to the introduction pipe 21. The reaction tank T may also be equipped with a stirring mechanism for stirring and mixing the water to be treated W and adsorbent A (not shown).

[0062] Reaction tank T is used to mix the water to be treated W with adsorbent A and to perform adsorption treatment of dissolved organic matter in the water to be treated W. The amount of adsorbent A to be added to the reaction vessel T can be calculated and determined by the same means as described in the first embodiment.

[0063] In the reaction tank T, the stirring time and stirring speed of the water to be treated W and the adsorbent A are controlled in order to advance the adsorption treatment of dissolved organic matter by the adsorbent A. It is also preferable to control the time (residence time) from when the water to be treated W is introduced from line L3 until it is mixed with the adsorbent A and discharged from line L4. This allows the adsorption process to proceed in the reaction tank T for the amount of organic matter M corresponding to the organic matter concentration (difference C3) to be treated in the coagulation and sedimentation tank 1 during the treatment of the water to be treated W. In particular, by allowing the water to remain in the reaction tank T for the time required for the adsorption of the amount of organic matter M, it is possible to ensure that sufficient adsorption of the amount of organic matter M has been achieved when the water to be treated W is supplied to the coagulation and sedimentation tank 1.

[0064] If the adsorption process using adsorbent A and the flocculation process using a flocculant are performed in the same or adjacent location, the contact efficiency between adsorbent A and dissolved organic matter may be reduced. On the other hand, in the flocculation-settling treatment apparatus 100B of this embodiment, a reaction tank T is provided, and the adsorption process of organic matter amount M proceeds in the reaction tank T, so that mainly only the flocculation-settling treatment process proceeds in the flocculation-settling tank 1. Therefore, in the flocculation-settling treatment apparatus 100B, it is possible to carry out the adsorption process and the flocculation-settling treatment process separately. As a result, the adsorption process proceeds reliably, and in the flocculation-settling treatment in the flocculation-settling tank 1, the used adsorbent A can be easily separated and recovered without affecting the flocculation-settling treatment efficiency.

[0065] As described above, the coagulation and sedimentation treatment apparatus 100B of this embodiment can adsorb an amount of organic matter equivalent to the difference between the first organic matter concentration and the second organic matter concentration in the water to be treated before it is introduced into the treatment tank. This makes it possible to separate the process related to coagulation and sedimentation from the process related to adsorption, and to reliably perform adsorption of a specific amount of organic matter. As a result, it is possible to perform appropriate treatment in terms of both treatment cost and treatment performance as a coagulation and sedimentation treatment of water to be treated that contains dissolved organic matter. In particular, it is possible to perform an even more appropriate treatment in terms of treatment performance.

[0066] 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.

[0067] For example, the coagulation and sedimentation treatment apparatus of this embodiment uses a double-structured coagulation and sedimentation tank with an outer wall and an inner wall as a sludge blanket type treatment tank, but it is not particularly limited as long as the sludge blanket section and the concentration section are provided as independent components. For example, in another embodiment of the sludge blanket type treatment tank, a bottom plate is placed horizontally in the coagulation and sedimentation tank, and a side wall extends upward from a part of the outer edge of the bottom plate and is connected to the peripheral wall of the coagulation and sedimentation tank, thereby forming a fluidized bed of flocs (sludge blanket section) in a section defined above the bottom plate and on the inner side of the side wall, while the section defined below the bottom plate and on the outer side of the side wall is used as the concentration section.

[0068] Furthermore, for example, the coagulation and sedimentation apparatus of this embodiment may be provided with an extraction line in the sludge blanket section to extract flocs and return the extracted flocs to the inlet pipe side. This makes it possible to form good sludge (coagulated flocs) using the extracted flocs as seed crystals, and thus obtain good treated water. [Industrial applicability]

[0069] The coagulation and sedimentation apparatus and coagulation and sedimentation method of the present invention are suitably used for the coagulation and sedimentation treatment of water to be treated that contains dissolved organic matter. [Explanation of Symbols]

[0070] 100A, 100B Coagulation and Sedimentation Treatment System, 1 Coagulation and Sedimentation Tank, 11 Outer Wall, 12 Inner Wall, 13 Partition Plate, 13a Opening, 14 Center Shaft, 15 Rotary Joint, 16 Motor, 2 Water Treatment Inlet, 21 Inlet Pipe, 22 Feed Pipe, 22a Upper Part, 22b Lower Part, 23 Rotary Joint, 24 Distributor, 24a Water Treatment Outlet, 3 Sludge Blanket Section, 4 Concentration Section, 41 Concentrated Sludge Scraper, 5 Coagulant Addition Section, 51 Coagulant Supply Line, 6 Treated Water Discharge Section, 7 Sludge Discharge Section, 8 Adsorbent Addition Section, 81, 82 Adsorbent Supply Line, A Adsorbent, C Clarification Layer, F Floc, L Axis, L1~L4 Line, P Pump, T Reaction Tank, W Water Treatment, W1 Treated Water, Z1 Floc growth zone, Z2 floc concentration zone, C1 first organic matter concentration, C2 second organic matter concentration, C3 difference between first and second organic matter concentrations, M amount of organic matter corresponding to the difference between first and second organic matter concentrations.

Claims

1. A coagulation and sedimentation tank is used to coagulate and sedimentate the wastewater to be treated, The system includes an adsorbent addition section for adding an adsorbent that adsorbs organic matter contained in the water to be treated, The amount of adsorbent added is an equivalent amount capable of adsorbing an amount of organic matter corresponding to the difference between a first dissolved organic matter concentration contained in the water to be treated and a second dissolved organic matter concentration set in the coagulation and sedimentation tank, wherein the amount of adsorbent added is an equivalent amount capable of adsorbing an amount of organic matter corresponding to the difference between a first dissolved organic matter concentration contained in the water to be treated and a second dissolved organic matter concentration set in the coagulation and sedimentation tank.

2. The coagulation and sedimentation apparatus according to claim 1, characterized in that the adsorbent is activated carbon.

3. The coagulation and sedimentation apparatus according to claim 1 or 2, characterized in that the adsorbent and the water to be treated are mixed in the preceding stage of the coagulation and sedimentation tank and allowed to remain for the time required for the adsorption of the amount of organic matter.

4. The system includes a coagulant addition unit for adding a coagulant to the water to be treated, The coagulation and sedimentation apparatus according to any one of claims 1 to 3, characterized in that the adsorbent addition section is provided upstream of the coagulant addition section.

5. The coagulation and sedimentation process involves treating the wastewater (water to be treated) with coagulation and sedimentation, The process includes an adsorbent addition step of adding an adsorbent that adsorbs organic matter contained in the water to be treated, A coagulation and sedimentation treatment method characterized in that the amount of adsorbent added is an equivalent amount capable of adsorbing an amount of organic matter corresponding to the difference between the first dissolved organic matter concentration contained in the water to be treated and the second dissolved organic matter concentration set in the coagulation and sedimentation step.

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