Water treatment equipment

Abstract

To provide a water treatment device capable of obtaining treated water that satisfies sewage discharge standard further efficiently with less dilution.SOLUTION: A water treatment device comprises a dehydrator that dehydrates treated water containing at least one of septic tank sludge and human waste sludge and separates the same into separated sludge and dehydrated separation liquid, phosphorus supply means that supplies phosphorus to at least a part of the dehydrated separation liquid so that the phosphorus concentration is 0.7 mg / L or less per 100 mg / L BOD, a biological treatment tank that performs biological treatment using a non-clogging biological membrane method that includes at least one of a diffusion filter bed method, a fluidized bed method, a rotating disk method, and a fixed bed method with respect to the dehydrated separation liquid after supplying phosphorus, and a dilution tank that dilutes the biological treated water obtained through the biological treatment to meet sewage exclusion standards.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a water treatment device, and more particularly to a water treatment device suitable for use in water treatment in which septic tank sludge and sewage sludge are treated and treated water is discharged into a sewer system. [Background technology]

[0002] In order to discharge treated water obtained by treating raw water containing septic tank sludge and human waste sludge into a sewerage system, it is necessary to satisfy sewage discharge standards, but sewage discharge standards are generally known to be more lenient than standards for discharge into public water bodies. For example, while the standards for discharge into public water bodies are 10 mg / L BOD (biochemical oxygen demand), 10 mg / L N (nitrogen), and 10 mg / L SS (suspended solids), the sewage discharge standards are 600 mg / L BOD, 240 mg / L TN, and 600 mg / L SS.

[0003] Conventional methods for treating sewage effluent include, for example, removing waste (screen waste) from human waste and diluting the water to the sewage discharge standard before discharging it. In this case, the dilution rate is generally about 10 to 20 times, which results in excessive amounts of dilution water and effluent into the sewer system.

[0004] Another treatment method is to separate the sewage and other waste into solids and liquids using a dehydrator, dilute the dehydrated liquid, and release it into the sewer system. In this case, the dehydrated liquid contains significantly less BOD, SS, nitrogen, and other components than the sludge-removed liquid, so the dilution ratio can generally be about 3 to 8 times. However, the water quality of the dehydrated liquid varies, so the amount of dilution water also varies greatly depending on the water quality.

[0005] Furthermore, the method of separating sewage and other waste into solid and liquid form using a dehydrator ultimately results in discharging 4 to 9 times the amount brought in, so the effect of reducing the amount of wastewater discharged into the sewerage system is limited. Since soluble components are difficult to remove with solid-liquid separation, if the sewage and other waste contains a large amount of soluble components, the quality of the separated liquid from the dehydration process may deteriorate, making it necessary to increase the amount of dilution water. There are also cases where regulations on the amount of wastewater discharged make it impossible to meet the sewage discharge standards.

[0006] Another method for more reliably reducing the amount of dilution water and discharge water is to combine solid-liquid separation with biological treatment. For example, JP-A-61-50691 (Patent Document 1) describes a method in which the solid content obtained by solid-liquid separation of septic tank sludge is mixed with human wastewater, which is subjected to coagulation treatment, and the separated liquid is subjected to biological treatment. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 61-50691 Summary of the Invention [Problem to be solved by the invention]

[0008] The method described in Patent Document 1 does not state where the biologically treated water is discharged. However, since the treated water in Example 1 can be treated until the BOD level reaches 10 mg / L or less, it can be inferred that the treatment method is intended for discharge into public water areas.

[0009] However, as mentioned above, sewage discharge standards tend to be looser than standards for discharge into public water areas, and treated water to be discharged into sewers is not required to have the water quality mentioned in Patent Document 1. Therefore, it is desirable to propose a more efficient and appropriate treatment method that meets the water quality standards for discharge into sewers.

[0010] On the other hand, in the water treatment method that combines solid-liquid separation and biological treatment as described in the cited document 1, there is a problem in that it is difficult to perform partial treatment to a degree that satisfies the sewage discharge standards.

[0011] For example, when nitrification-denitrification is used as a biological treatment, it is possible to use a method in which only about 60% of the nitrogen is treated rather than the entire amount, or a method in which all of the ammonia nitrogen contained in the dehydration separation liquid is nitrified and then only 60% of it is denitrified.

[0012] However, when treating about 60% of the nitrogen, about 40% of the nitrate nitrogen remains, and denitrification occurs again in the downstream settling tank where the anaerobic conditions are created, and the nitrogen gas generated causes the sludge to float, which may prevent sufficient solid-liquid separation in the settling tank.If solid-liquid separation is not possible in the settling tank, the MLSS (MLSS concentration) of the nitrification / denitrification tank cannot be maintained, and the treatment itself will deteriorate.

[0013] If all of the ammonia nitrogen contained in the dehydration separation liquid is nitrified, the capacity of the water tank will be excessive, the aeration air volume required for nitrification will be excessive, and hydrogen donors such as methanol and ethanol, which are necessary for denitrification, will need to be added, resulting in excessive equipment and operating costs compared to the required treated water quality.

[0014] Another method is to use biological treatment using the activated sludge method to roughly treat the treated water until the water quality falls below the sewage discharge standard, then dilute it and discharge it into the sewer. In this case, it is possible to solve the above-mentioned problems caused by incomplete biological treatment using nitrification / denitrification by treating with a high BOD load that does not cause nitrification, but an appropriate tank capacity is required for biological treatment using the activated sludge method, and the aeration air volume to deal with the high BOD load is also excessive, so it cannot be said to be a good method for efficient treatment.

[0015] In view of the above problems, the present invention provides a water treatment device that can more efficiently obtain treated water that satisfies sewage removal standards with a smaller amount of dilution water. [Means for solving the problem]

[0016] As a result of intensive research conducted by the present inventors in order to solve the above problems, it was discovered that it is effective to subject at least a portion of the dehydrated separated liquid obtained by solid-liquid separation using a dehydrator from water to be treated that contains at least one of septic tank sludge and sewage sludge to a specific biological treatment and then to a dilution treatment.

[0017] In one aspect, a water treatment method according to an embodiment of the present invention, which was completed based on the above findings, is a water treatment method which includes: performing solid-liquid separation using a dehydrator to separate water to be treated, which contains at least either septic tank sludge or sewage sludge, into separated sludge and a dehydrated separated liquid; subjecting at least a portion of the dehydrated separated liquid to biological treatment using a non-blocking biofilm method which includes at least any one of a trickling filter method, a fluidized carrier method, a rotating disk method and a fixed bed method; and diluting the biologically treated water obtained by the biological treatment so as to satisfy the sewage removal standards.

[0018] In one embodiment of the water treatment method according to the present invention, the biological treatment includes treating the dehydrated separated liquid by connecting in parallel or in series a biological treatment tank for removing BOD from the dehydrated separated liquid and a biological treatment tank for removing nitrogen from the dehydrated separated liquid.

[0019] In another embodiment of the water treatment method according to the present invention, the biological treatment includes stepwise inflow of the dewatered separated liquid into biological treatment tanks connected in series in two or more stages.

[0020] In still another embodiment of the water treatment method according to the embodiment of the present invention, the biological treatment includes supplying the dehydrated separated liquid to a trickling filter to aerobic decomposition of BOD in the dehydrated separated liquid and nitrification of ammonia nitrogen to obtain biologically treated water, circulating the biologically treated water through the trickling filter, and placing a carrier in a circulation tank that contains the circulating water to be circulated to the trickling filter, and causing a denitrification reaction to proceed by microorganisms attached to the carrier.

[0021] In one aspect, a water treatment device according to an embodiment of the present invention is a water treatment device comprising: a dehydrator that dehydrates water to be treated, which contains at least either septic tank sludge or sewage sludge, and separates the water into separated sludge and a dehydrated separated liquid; a biological treatment tank that performs biological treatment on at least a portion of the dehydrated separated liquid using a non-blocking biofilm method that includes at least any one of a trickling filter method, a fluidized carrier method, a rotating disk method, and a fixed bed method; and a dilution tank that dilutes the biologically treated water obtained by the biological treatment so that it meets the sewage removal standards.

[0022] In another embodiment of the water treatment device according to the present invention, a membrane carrier having a structure in which the dehydrated separated liquid and oxygen permeate in opposing directions across the membrane surface is disposed in the biological treatment tank.

[0023] In yet another embodiment of the water treatment device according to the present invention, the membrane carrier comprises a support and a membrane supported by the support, the membrane has a loop shape covering the support, the dehydration separated liquid permeates from the outer surface of the membrane, oxygen permeates from a space formed on the inner surface of the membrane to the outer surface of the membrane, and an opening is formed in the membrane for discharging sludge peeling off from the inner surface of the membrane to the outside of the space.

[0024] In yet another embodiment, a water treatment device according to an embodiment of the present invention includes an inflow means for inflowing dehydrated separated liquid in steps into each of the biological treatment tanks, which include two or more treatment tanks connected in series, and a control means for controlling the step ratio of the dehydrated separated liquid to be flowed into the biological treatment tank based on the volume load of the biological treatment tank and the water quality of the dehydrated separated liquid or the biological treatment water. Effect of the Invention

[0025] According to the present invention, a water treatment device can be provided that can more efficiently obtain treated water that satisfies sewage removal standards with a smaller amount of dilution water. [Brief description of the drawings]

[0026] [Figure 1] 1 is a schematic diagram illustrating a water treatment device according to a first embodiment. [Diagram 2] FIG. 11 is a cross-sectional view showing an example of a membrane carrier provided in a water treatment device according to a second embodiment. [Diagram 3] FIG. 11 is a side view showing an example of a membrane carrier included in a water treatment device according to a second embodiment. [Figure 4] FIG. 11 is a schematic diagram illustrating a water treatment device according to a third embodiment. [Diagram 5] FIG. 13 is a schematic diagram illustrating a water treatment device according to a fourth embodiment. [Figure 6]FIG. 13 is a schematic diagram illustrating a water treatment device according to a fifth embodiment. [Figure 7] FIG. 13 is a schematic diagram illustrating a water treatment device according to a sixth embodiment. [Figure 8] FIG. 13 is a schematic diagram illustrating a water treatment device according to a seventh embodiment. [Figure 9] FIG. 13 is a schematic diagram illustrating a water treatment device according to a modified example of the seventh embodiment. [Figure 10] 1 is a graph showing the results of confirming the transition of the BOD set load in each tank when the water treatment method of the embodiment is used. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] <Water treatment method> A water treatment method according to an embodiment of the present invention includes subjecting water to solid-liquid separation, which contains at least either septic tank sludge or sewage sludge, to separated sludge and separated liquid, subjecting at least a portion of the separated liquid to biological treatment using a non-blocking biofilm method which includes at least any one of a trickling filter method, a fluidized carrier method, a rotating disc method, and a fixed bed method, and diluting the biologically treated water so that it meets the sewage removal standards.

[0028] (Water to be treated) The water to be treated is not particularly limited as long as it contains at least one of septic tank sludge and human waste sludge. For example, in the case of using a mixture of human waste sludge and septic tank sludge as the water to be treated, it is preferable to separate the human waste sludge and the septic tank sludge from each other in solid-liquid separation.

[0029] (solid-liquid separation) For the solid-liquid separation treatment, various solid-liquid separation devices can be used, but for example, it is preferable to separate the solid-liquid into separated sludge and separated liquid using a dehydrator in terms of equipment and operation costs. Furthermore, it is more preferable to perform a concentration treatment on the water to be treated before solid-liquid separation. As a concentration method, both gravity concentration and mechanical concentration are effective concentration methods.

[0030] By performing a concentration process in which a polymer flocculant is added before solid-liquid separation, the sludge concentration (TS) of the concentrated sludge can be increased to a maximum of approximately 10 to 12 mass%. If the concentrated sludge is further dehydrated using a dehydrator, dehydrated sludge (separated sludge) with a low moisture content of 70% or less can be obtained, resulting in a more significant sludge volume reduction effect. As this dehydrated sludge with a low moisture content has a high calorie content, it can be self-burned without auxiliary fuel during incineration, resulting in energy savings and low costs.

[0031] (Biological treatment) Biological treatment using the biofilm process can be broadly divided into those that require a periodic cleaning process for the carrier, and those in which the amount of biofilm is autonomously controlled during treatment. The former includes the biofilm filtration method, while the latter includes the trickling filter method, fluidized carrier method, rotating disk method, and fixed bed method (contact oxidation method).

[0032] Among these, it is preferable to use a biofilm process in which the amount of biofilm is autonomously controlled during the treatment as the biological treatment according to the embodiment of the present invention, and this is defined in the present specification as a "non-blocking type biofilm process." In particular, among the non-blocking type biofilm processes, the trickling filter process and the fluidized bed process are suitable for a BOD volumetric loading of 1 kg-BOD / m. 3 / d or more, it is possible to operate stably, and it is effective when the site area is limited. Specific examples of biological treatments included in this "non-blocking biofilm process" are explained below.

[0033] -Trickling filter method- The trickling filter method is one of the aerobic biochemical treatment methods, in which the action of microorganisms attached to the surface of the filter media decomposes organic matter in the water to be treated (separate liquid) that is sprayed onto it, producing biologically treated water. In the trickling filter method, it is generally known that the surface of the biofilm becomes aerobic and the inside of the biofilm becomes anaerobic. For this reason, when the trickling filter is operated with a load that allows nitrification to proceed, the nitrification reaction proceeds on the surface of the biofilm and the denitrification reaction proceeds inside the biofilm, making it excellent in terms of nitrogen removal efficiency.

[0034] There are no particular limitations on the specific configuration of the carrier, the trickling part, etc. used in the trickling filter. Any material may be used for the carrier as long as microorganisms can adhere to it, and representative examples include plastic and crushed stone. The shape of the carrier may be any shape, such as a plate, sphere, cylinder, rectangular parallelepiped, hollow, etc. The loading rate of the carrier relative to the volume of the reaction vessel is preferably 40 to 80%, and more preferably 50 to 70%. In the case of a membrane carrier, the surface area of ​​the membrane relative to the volume of the reaction vessel is preferably 0.05 to 0.15 m. 2 / m 3 It is preferable to fill the mixture so that

[0035] In order to carry out biological treatment more efficiently and stably, it is preferable to place a membrane carrier in the trickling filter having a structure in which the separated liquid after solid-liquid separation supplied to the trickling filter and the oxygen in the trickling filter permeate in opposing directions across the membrane surface.

[0036] The membrane carrier has an area rich in BOD and poor in oxygen on the separated liquid supply side, while the oxygen supply side is an area poor in BOD and rich in oxygen. Therefore, it is possible to create conditions suitable for the progress of denitrification reactions on the supply side of the water to be treated (separate liquid), while creating conditions suitable for nitrification reactions on the oxygen supply side, making it more suitable than other carriers in terms of its excellent nitrogen removal performance.

[0037] In contrast, in the case of a normal granular carrier, BOD, nitrogen, and oxygen are supplied to the biofilm on the carrier surface from the same direction, resulting in a rate of 1 to 1.5 kg-BOD / m 3 At a load of 1.5 kg-BOD / m2 / day, oxygen is consumed by the oxidation of BOD, and the nitrification-denitrification reaction may not proceed smoothly. In addition, the membrane carrier has a lower BOD load of 1.5 kg-BOD / m2 than treatment methods using other types of carriers. 3 This has the advantage that it can operate stably without clogging even under high load conditions of 1000m3 or more / d. This is because the membrane carriers are arranged vertically, and the biofilm that detaches from the carriers is discharged outside the tank without clogging between the carriers.

[0038] The separated liquid after solid-liquid separation is introduced into the trickling filter bed after being transferred to the upper part of the trickling filter bed using a siphon, etc. When the separated liquid is to be sprinkled over the entire filter bed, any sprinkling device such as a perforated plate, a sprinkler type or a spiral type nozzle, or a self-propelled rotary sprinkler can be used.

[0039] -Fluid Carrier Method- The floating carrier method is a method in which carriers are placed in a biological treatment tank and the carriers are allowed to flow within the biological treatment tank, thereby bringing microorganisms into contact with organic matter and oxygen in the water to be treated, thereby obtaining biologically treated water. A biological treatment tank using the floating carrier method may be newly constructed, or carriers, an aeration device, etc. may be installed in an existing storage tank, etc. There are no particular limitations on the carriers used as floating carriers, but the following are some typical examples.

[0040] The carrier to be used may be any carrier that can be attached to microorganisms and can be fluidized by aeration. The material of the carrier may be any carrier that can be fluidized by aeration, for example, plastic (polyurethane (PU), polyethylene (PE), polyethylene glycol (PEG), polyvinyl alcohol (PVA)), wood chips, sand, etc. are used. The carrier may have a sponge-like, gel-like, solid, etc. shape. The carrier may have any shape, such as a spherical, cubic, cylindrical, honeycomb, etc. Among them, by using a bonded immobilized carrier that attaches microorganisms to the outer surface of the carrier, microorganisms suitable for the environment in the biological treatment tank can be attached to the carrier, and the biological treatment can be performed more stably without being affected by fluctuations in the properties of the inflow water. The carrier filling rate is preferably 20 to 40% from the viewpoint of fluidity and performance. A filling rate of 20% or more allows a large amount of microorganisms to be retained in the tank, and a filling rate of 40% or less allows the creation of appropriate voids to maintain good fluidity. The BOD load of the fluidized carrier method is 0.5 to 5.0 kg-BOD / m 3 / d, preferably 1.0-3.0kg-BOD / m 3 / d is preferred. The fluidized bed method is suitable for cases where an aeration tank for existing activated sludge is used.

[0041] -Rotating disk method- The rotating disk process is a method in which a part of a rotating disk is exposed to the water to be treated and the outside air, forming a biofilm on the surface of the disk and decomposing the organic matter in the water to be treated (separate liquid) to obtain biologically treated water. Since aeration is not performed, there is no need to install a blower that requires air volume adjustment, and there is no need to supply return sludge as in the activated sludge process, so it has the advantage of being able to supply simpler equipment. The BOD load of the rotating disk process is 0.1 to 1.5 kg-BOD / m 3 / d is preferable, and if an excessive load is applied, problems may occur in which excessive microorganisms adhere to the disk and the rotating shaft is damaged.

[0042] There is no particular restriction on the material and specific shape of the disk, and any device can be used. For example, the disk can be made of polystyrene foam, plastic, polyvinyl chloride, waterproof plywood, or metal plate such as aluminum, and can be formed into a disk shape with a diameter of 1 to 3 m and a thickness of 0.7 to 20 mm.

[0043] -Fixed bed method (catalytic oxidation method)- In the contact oxidation method, a fixed bed carrier is immersed in a reaction tank and aeration is performed while the water to be treated is passed through it, forming a biofilm on the surface of the carrier, which decomposes the organic matter in the water to be treated (separate liquid) to obtain biologically treated water. As treatment is performed using a biofilm attached to the carrier, there is no need to control the amount of sludge by returning it, as in the activated sludge method, making maintenance and management easier. The BOD load is 0.1 to 1.0 kg-BOD / m 3 / d is preferable, and operation at high load may cause the biofilm to swell and clog the contact material.

[0044] There is no particular restriction on the material and specific shape of the carrier for the contact oxidation method, and any device can be used. The carrier can be made of polyethylene, plastic, etc., and can be in any shape, such as a tube, string, net, plate, ball, etc.

[0045] (Dilution ratio) The biologically treated water obtained by the above biological treatment is sent to a dilution tank and mixed with dilution water to be diluted so as to meet the sewage discharge standard. According to this embodiment, the dilution rate is typically 1 to 4 times, more typically 1 to 3 times, and even 1 to 2 times, so that the amount can meet the sewage discharge standard. Dilution may be performed continuously, or may be performed only when necessary to meet the sewage discharge standard. This allows more efficient and appropriate treatment in accordance with the water quality standard for discharge into the sewerage system to be performed with a smaller amount of dilution water than in the conventional method.

[0046] According to the present embodiment, the biological treatment may be performed to such an extent that dilution of the biologically treated water is not necessary. In such a case, the biologically treated water obtained after biological treatment using a non-blocking biofilm method including either the trickling filter method or the fluidized bed method on at least a part of the separated liquid may be discharged into a sewer without dilution.

[0047] According to the water treatment method of the embodiment of the present invention, by subjecting at least a portion of the separated liquid obtained by solid-liquid separation of water to be treated, which contains at least either septic tank sludge or sewage sludge, to biological treatment using the non-blocking biofilm method described above and then diluting it, it is possible to more efficiently and stably obtain treated water that can be discharged into the sewerage system using a small amount of dilution water.

[0048] Furthermore, according to the water treatment method of this embodiment, biological treatment is used to treat the separated liquid obtained by solid-liquid separation. Therefore, by supplying the amount of phosphorus necessary for the growth of microorganisms in the biological treatment tank, the water quality of the treated water by the biological treatment can be maintained at a higher level and stabilized.

[0049] Generally, in biological treatment, about 1 mg / L of phosphorus is required for a BOD of 100 mg / L. Therefore, it is desirable to supply phosphorus so as to satisfy this ratio with respect to the BOD of the influent (separate liquid). If the treatment is satisfactory, the phosphorus concentration may be reduced to 1 mg / L or less, preferably 0.7 mg / L or less, and more preferably 0.5 mg / L or less before supplying.

[0050] In particular, when iron- or aluminum-based coagulants are used in the dewatering process of septic tank sludge and sewage sludge, phosphorus is absorbed into the sludge, lowering the phosphorus concentration in the dewatered separated liquid, so adding phosphorus can produce treated water of more stable quality. In crude treatment, the supply of nutrients such as phosphorus tends to be overlooked, but a phosphorus deficiency can make it almost impossible to remove BOD, so in fact, even in crude treatment, it is often important to supply phosphorus.

[0051] Hereinafter, first to seventh embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are given the same or similar reference numerals. Note that the following embodiments are merely examples of devices and methods for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention does not limit the structure, arrangement, etc. of the components to those described below. Furthermore, it is of course possible to combine each configuration described in each of the following embodiments with a water treatment device according to another embodiment.

[0052] (First embodiment) As shown in FIG. 1, the water treatment device according to the first embodiment includes a solid-liquid separation device 1 that separates water to be treated, which contains at least one of septic tank sludge and sewage sludge, into separated sludge and separated liquid by solid-liquid separation, a biological treatment tank 2 that performs biological treatment on the separated liquid using a non-blocking biofilm method, i.e., a trickling filter method, a fluidized carrier method, a rotating disk method, or a fixed bed method, and a dilution tank 3 that dilutes the biologically treated water so that it meets the sewage removal standards.

[0053] In an embodiment of the treatment (BOD removal type) in which the BOD in the biologically treated water is the basis for determining the dilution ratio, it is preferable to provide a dehydrator as the solid-liquid separation device 1 and a trickling filter as the biological treatment tank 2. Treatment conditions for the trickling filter include, for example, a BOD volumetric load of 0.5 to 7.5 kg-BOD / m 3 / d, and in another embodiment, 1.0 to 5.0 kg-BOD / m 3 / d.

[0054] The water to be treated is separated into solid and liquid by a solid-liquid separator 1, and a separated liquid and separated sludge having a BOD of, for example, 600 to 10,000 mg / L, more typically 1,000 to 5,000 mg / L are obtained. The separated liquid is then introduced into a biological treatment tank 2, where the BOD is roughly removed, and biologically treated water having a BOD of about 600 to 3,000 mg / L is obtained. The biologically treated water is mixed with dilution water in a dilution tank 3, and is diluted until it meets the sewage discharge standard, and then discharged into a sewerage system. Note that, instead of a trickling filter bed, a fluidized bed carrier tank, a contact oxidation tank, or a rotating disk device can also be used as the biological treatment tank 2.

[0055] According to the water treatment device and water treatment method of the first embodiment, biologically treated water that has been biologically treated using a trickling filter, a fluidized bed carrier tank, a contact oxidation tank, a rotating disk device, or the like that have traditionally been used as a biological treatment tank 2 for septic tank sludge and sewage sludge is diluted with dilution water. This makes it possible to omit the power required for aeration, as compared to treatment using the activated sludge method, etc., and also in terms of equipment, treated water for discharge into the sewerage can be efficiently obtained using simpler equipment.

[0056] (Second embodiment) The water treatment device of the second embodiment includes a membrane carrier 20 (see Figures 2 and 3) arranged in the biological treatment tank 2 of Figure 1, the membrane carrier 20 having a structure in which the separated liquid and oxygen permeate opposite each other across the membrane surface.

[0057] 2, the membrane carrier 20 includes a support 21 and a membrane 22 supported by the support 21, the membrane 22 has a loop shape that covers the support 21, and is configured so that the separated liquid permeates from the outer surface of the loop-shaped membrane 22, and oxygen permeates from a space 23 formed on the inner surface of the loop-shaped membrane 22 to the outer surface of the membrane. The membrane 22 includes a curved portion 22a that curves outside the support 21, and extension portions 22b and 22c that extend approximately parallel to each other from both ends of the curved portion 22a, and an opening 22d is formed on the lower end side of the membrane 22, i.e., on the side of the membrane 22 facing the bottom surface of the biological treatment tank 2, for discharging sludge (not shown) that accumulates on the inner surface of the membrane 22 and is subsequently peeled off, out of the space 23.

[0058] 2 and 3 is housed in a trickling filter serving as the biological treatment tank 2, so that the outside of the membrane 22 of the membrane carrier 20, which is the separated liquid supply side, becomes an area rich in BOD and poor in oxygen, while the oxygen supply side inside the membrane 22 becomes an area poor in BOD and rich in oxygen. Therefore, it is possible to create conditions suitable for the progress of denitrification reactions on the separated liquid supply side, while creating conditions suitable for nitrification reactions on the oxygen supply side.

[0059] According to the water treatment device and water treatment method of the second embodiment, by using the membrane carrier 20 having the structure shown in Fig. 2 and Fig. 3, an area with low oxygen and an area with abundant oxygen can be reliably formed in a certain area, compared to the case where sand or stone is used as a filter medium. Therefore, an environment in which the nitrification-denitrification reaction is more likely to proceed can be created compared to the case where sand or stone is used as a filter medium. In addition, since the sludge accumulated on the inner surface of the membrane 22 can be discharged from the opening 22d, it becomes possible to perform stable treatment for a longer period of time. Since much of the discharged sludge is detached from living organisms and this sludge has good settling properties, it is preferable to supply solid-liquid separated water to the dilution tank via a solid-liquid separation device such as a sedimentation tank. The separated sludge is returned to the receiving tank before the dehydration equipment for septic tank sludge and sewage sludge, dehydrated, and discharged outside the facility as dehydrated cake.

[0060] (Third embodiment) As shown in FIG. 4, the water treatment device of the third embodiment includes a biological treatment tank 2, which is a biological treatment tank (high-load biological treatment tank) 2a for removing BOD from the separated liquid and a biological treatment tank (low-load biological treatment tank) 2b for removing nitrogen from the separated liquid, connected in parallel to each other.

[0061] The BOD load condition of the biological treatment tank 2a is, but is not limited to, 3.0 to 10.0 kg-BOD / m 3 / d, and in other embodiments, 3.0 to 8.0 kg-BOD / m 3 / d, and in another embodiment, 3.0 to 5.0 kg-BOD / m 3In the biological treatment tank 2a, treatment is carried out for the purpose of roughly removing the BOD from the separated liquid.

[0062] The BOD load condition of the biological treatment tank 2b is preferably lower than that of the biological treatment tank 2a, and is not limited to the following, for example, 0.5 to 2.0 kg-BOD / m 3 / d, and in other embodiments, 0.5 to 1.5 kg-BOD / m 3 / d, and in another embodiment, 0.5 to 1.0 kg-BOD / m 3 / d. In the biological treatment tank 2b, treatment is carried out with the aim of removing TN (total nitrogen) from the separated liquid.

[0063] The inflow ratio of the separated liquid to the biological treatment tank 2a and the biological treatment tank 2b can be adjusted depending on the water quality (BOD, TN) of the separated liquid. Although not shown, a control means may be provided for controlling the inflow ratio of the separated liquid to the biological treatment tank 2a and the biological treatment tank 2b based on the water quality of the separated liquid. Note that, although FIG. 4 shows an example in which the biological treatment tank 2a and the biological treatment tank 2b are connected in parallel as two biological treatment tanks 2, it goes without saying that two or more biological treatment tanks may be provided.

[0064] According to the water treatment device and water treatment method of the third embodiment, more appropriate treatment can be performed by using multiple biological treatment tanks 2 depending on the purpose of removing organic matter from the separated liquid, so that treated water that meets sewage removal standards can be produced more efficiently.

[0065] (Fourth embodiment) 5, the water treatment device according to the fourth embodiment includes a biological treatment tank 2 connected in series with a biological treatment tank (high-load biological treatment tank) 2a for removing BOD from the separated liquid and a biological treatment tank (low-load biological treatment tank) 2b for removing nitrogen from the separated liquid, as the biological treatment tank 2. The biologically treated water finally obtained by the treatment in the biological treatment tanks 2a and 2b is circulated to the front stage of the biological treatment tanks 2a and 2b via a return means 4.

[0066] According to the water treatment device and water treatment method of the fourth embodiment, BOD removal is performed in the upstream biological treatment tank 2a and the nitrification reaction is allowed to proceed in the downstream biological treatment tank 2b. Furthermore, by returning the biologically treated water using the return means 4, circulating nitrification and denitrification can be further promoted, thereby enabling more stable water treatment to be performed for discharge into a sewerage system.

[0067] (Fifth embodiment) As shown in FIG. 6, the water treatment device of the fifth embodiment has two or more stages of biological treatment tanks 2a, 2b, .... 2n connected in series, and has an inflow means 5 for introducing separated liquid into each of the biological treatment tanks 2a, 2b, .... 2n in a stepwise manner.

[0068] The inflow rate (step ratio) to each biological treatment tank 2a, 2b, ... 2n can be changed as desired. From the viewpoint of nitrogen removal, the BOD volumetric load should be 1.0 to 4.0 kg-BOD / m 3 / d, preferably 1.5-3.0kg-BOD / m 3 / d, TN volume load 0.5~2.0kg-N / m 3 / d, preferably 0.7 to 1.5 kg-N / m 3 It is desirable to determine the ratio of each step so that the biological treatment tanks 2a, 2b, . . . 2n each satisfying the above condition are included, and the number of such tanks is further increased.

[0069] The flow rate of the treated water is 12m 3 / d, BOD 2000mg / L, NH4-N 700mg / L. Three biological treatment tanks 2 are connected in series, and the volume of each biological treatment tank 2 is 2m 3 Table 1 shows examples of the BOD and TN treated water quality when the step inflow rate of the separated liquid supplied from the inflow means 5 is changed. In cases A to C in Table 1, the example showing the best treated water quality is indicated by ◎, the example showing the second best treated water quality by ○, and the example showing the third best treated water quality by △.

[0070] [Table 1]

[0071] As shown in Table 1, when the inflow rate of the upstream step is reduced as in Case A, the TN treatment performance improves, while when the inflow rate of the upstream step is increased as in Case C, the BOD treatment performance tends to improve. This is because adjusting the load to allow nitrification to proceed in the upstream step, where it is possible to reduce the amount of treated water, contributes to nitrogen removal throughout the entire process.

[0072] In the water treatment device of the fifth embodiment, the inflow means 5 can adjust the distribution ratio of the amount of water flowing into each biological treatment tank 2a, 2b, .... 2n. Therefore, for example, the inflow amount on the upstream side of the biological treatment tanks 2a, 2b, .... 2n can be reduced to promote nitrification and increase the NO3-N concentration in the treated water, and in the downstream side, a denitrification reaction can be promoted between the NO3-N generated in the upstream side and the BOD components contained in the separated liquid flowing in as a step, thereby efficiently removing BOD and TN from the water to be treated.

[0073] Furthermore, according to the water treatment device of the fifth embodiment, since the treated water is not circulated as in the circulatory nitrification denitrification method, it is possible to reduce the pump power compared to the circulatory nitrification denitrification method.

[0074] (Sixth embodiment) As shown in FIG. 7, the water treatment device of the sixth embodiment includes an inflow means 5 for inflowing separated liquid into each biological treatment tank 2a, 2b, ...2n in steps, and a control means 6 for controlling the step ratio of the separated liquid to be inflowed into the biological treatment tanks 2a, 2b, ...2n.

[0075] The step ratio of the separated liquid through the inflow means 5 can be controlled by the control means 6 shown in FIG. 7 so that the treatment in each biological treatment tank 2a, 2b, .... 2n can be performed more stably depending on the volume load of each biological treatment tank 2a, 2b, .... 2n and the water quality of the separated liquid obtained from the solid-liquid separation device 1 or the biological treatment water obtained from the biological treatment tanks 2a, 2b, .... 2n.

[0076] For example, the control means 6 is equipped with a measuring means 11 that measures the water quality of the separated liquid obtained in the solid-liquid separation device 1, and a monitoring means 7 that monitors the measurement results of the measuring means 12, 13, and 14 that measure the water quality of the biological treatment water obtained in each biological treatment tank 2a, 2b, .... 2n, and based on the monitoring results of the monitoring means 7, the control means 6 adjusts the step ratio of the separated liquid to be flowed into each biological treatment tank 2a, 2b, .... 2n from the inflow means 5 so as to obtain a more optimal flow rate ratio according to the volume load of each biological treatment tank 2a, 2b, .... 2n.

[0077] There is no particular limit to the items monitored by the monitoring means 7, but for example, flow rate, water temperature, pH, ORP, BOD, COD, TOC, ammonia nitrogen, nitrate nitrogen, etc. The locations monitored by the monitoring means 7 are not limited to the example in Fig. 7, and it is also possible to pick out and monitor any of the representative biological treatment tanks 2a, 2b, ... 2n.

[0078] The control means 6 includes a calculation means (not shown) that calculates the step ratio of the separated liquid to be flowed into each of 2a, 2b, .... 2n based on the items monitored by the monitoring means 7, and adjusts the flow rate of the separated liquid flowing in from the inflow means 5 with a flow rate adjustment device based on the calculation result by the calculation means. Examples of the flow rate adjustment device include a solenoid valve, a manual valve, etc.

[0079] According to the water treatment device of the sixth embodiment, the water quality of the separated liquid obtained from the solid-liquid separation device 1 or the biological treatment water obtained from the biological treatment tanks 2a, 2b, .... 2n can be grasped in real time. Therefore, even if the water quality of the water to be treated fluctuates, the step ratio of the separated liquid can be set so that more appropriate biological treatment can be performed in each of the biological treatment tanks 2a, 2b, .... 2n, and more stable treatment can be performed.

[0080] (Seventh embodiment) In the water treatment device according to the seventh embodiment, as shown in Fig. 8, a biological treatment tank 2a and a biological treatment tank 2b are connected in parallel. The biological treatment tank 2a includes a trickling filter bed 201a for aerobic decomposition of BOD in the separated liquid and nitrification of ammonia nitrogen to obtain biologically treated water, a circulation line 203a for circulating the biologically treated water obtained in the trickling filter bed 201a to the trickling filter bed 201a, and a circulation tank 202a for accommodating the circulating water to be circulated to the trickling filter bed 201a. The biological treatment tank 2b includes a trickling filter bed 201b for aerobic decomposition of BOD in the separated liquid and nitrification of ammonia nitrogen to obtain biologically treated water, a circulation line 203b for circulating the biologically treated water obtained in the trickling filter bed 201b to the trickling filter bed 201b, and a circulation tank 202b for accommodating the circulating water to be circulated to the trickling filter bed 201b.

[0081] The separated liquid obtained by separating the treated water containing at least one of septic tank sludge and sewage sludge into solid and liquid is stored in a storage tank 2x and then supplied to the circulation tanks 202a and 202b of the biological treatment tanks 2a and 2b. In the dehydration treatment of septic tank sludge and sewage sludge, if a metal salt (polyiron, aluminum sulfate, etc.) is used as a flocculant, phosphorus in the raw water is chemically fixed to iron or aluminum, so that the phosphorus concentration in the separated liquid decreases. For this reason, a phosphorus supplying means 2y is connected to the upstream of the circulation tanks 202a and 202b, respectively, for supplying the amount of phosphorus necessary for the growth of microorganisms in the trickling filters 201a and 201b. There is no particular restriction on the form of phosphorus supplied from the phosphorus supplying means 2y, but there are methods such as adding chemicals such as phosphoric acid and potassium dihydrogen phosphate, or adding a portion of sewage sludge or septic tank sludge. When septic tank sludge and human waste sludge are used, the septic tank sludge and human waste sludge may be dispensed into the separated liquid storage tank after dehydration according to the amount of phosphorus that is insufficient.

[0082] 9, the circulation tank 202 can also be filled with carriers. In this case, by housing the carriers having microorganisms attached to their surfaces in the circulation tank 202 at 10-40% V / V, a denitrification reaction proceeds by the microorganisms housed in the circulation tank 202. After the denitrification reaction proceeds in the circulation tank 202 housing the carriers having microorganisms attached thereto, the circulating water can be circulated to the trickling filter bed 201, and the treated water can be returned to the circulation tank 202 again.

[0083] According to the water treatment device shown in FIG. 9, carriers having microorganisms attached to their surfaces are contained in the circulation tank 202, so that the organic matter (BOD) and nitrogen (TN) contained in the separated liquid can be efficiently and roughly removed stably regardless of fluctuations in the water to be treated.

[0084] According to the water treatment device of the seventh embodiment, there is no need to control the sludge concentration by returning the sludge, and it is possible to efficiently roughly remove the organic matter (BOD) and nitrogen (TN) contained in the separated liquid with easy maintenance and management without problems such as sludge re-floating, which makes it possible to reduce the amount of dilution water required to satisfy the sewage discharge standards and reduce the operating costs of the facility. EXAMPLES

[0085] Examples of the present invention will be described below together with comparative examples. These examples are provided for a better understanding of the present invention and its advantages, and are not intended to limit the invention.

[0086] As the separated liquid, the dehydrated separated liquid from a sewage treatment facility was supplied to the water treatment device shown in Figure 8 to obtain treated water. Nutrients (monopotassium phosphate (KH2PO4)) were added to the separated liquid. Table 2 shows the properties of typical separated liquids during the experiment.

[0087] [Table 2]

[0088] In the treatment flow, one trickling filter bed 201a in Figure 8 was connected in parallel as a high-load type (No. 1), and the other trickling filter bed 201b was connected in parallel as a low-load type (No. 2), and dehydrated separated liquid was flowed into each. The set load of each tank was gradually increased, and the treated water quality at each load was confirmed (see Figure 10). The outer dimensions of the trickling filter beds 201a and 201b were 0.05mW x 1.15mD x 2.42mH, and the effective volume was 2m. 3The membrane carriers shown in Figures 2 and 3 were used as the trickling filter beds 201a and 201b. The surface area of ​​the membrane carrier was 246 m 2 During the experiment, no sludge was returned from the treatment tank, and no control of the sludge volume was performed. The experimental results are shown in Table 3.

[0089] [Table 3]

[0090] High load conditions (3.0~10kg-BOD / m 3 / d), the TN removal rate was low at 18% or less, but the BOD removal rate was 38-62%, indicating that rough BOD removal is possible. 3 / d), the BOD removal rate was high at over 80%, and the TN removal rate was also 30-70%, demonstrating the possibility of rough removal of TN. Furthermore, under any of the load conditions, no problems such as sludge outflow or clogging occurred.

[0091] The relationship between the load and the amount of nitrification obtained from the above experiment is shown in Table 4. The amount of nitrification was 2.5 kg-BOD / m 3 From these results, when the purpose is to remove nitrogen, the BOD load should be 1.5 to 6.0 kg-BOD / m 3 / d, and even 1.5 to 4.0 kg-BOD / m 3 / d, and even 2.0 to 3.0 kg / m 3 It was found that the nitrogen removal efficiency could be increased by operating the reactor under a load condition of 10000 sq. m / d.

[0092] [Table 4]

[0093] Table 5 shows the calculated dilution ratios obtained from the removal rates of each load when the sewage discharge standards are BOD 600 mg / L and T-N 380 mg / L. Without biological treatment, a 3.8-fold dilution was necessary, but according to this embodiment, it was found that the dilution ratio can be reduced to 1.0 to 1.7 times. Note that the following calculations are based on the assumption that the entire amount of dehydrated filtrate is introduced into biological treatment, but it is self-evident that the amount of dilution water can be reduced even if only a portion of the dehydrated filtrate is biologically treated due to limitations in site area, etc.

[0094] [Table 5] [Explanation of symbols]

[0095] 1...Solid-liquid separator 2, 2a~2n…biological treatment tank 3...Dilution tank 4. Return method 5…Inflow means 6. Control means 7. Monitoring methods 11~14…Measurement means 20...Membrane carrier 21...Support 22...Membrane 23…Space 201, 201a, 201b...Trickling filter 202, 202a, 202b...Circulation tank 203a, 203b...Circulation line

Claims

1. a dehydrator that dehydrates water to be treated, the water including at least one of septic tank sludge and sewage sludge, and separates the water into separated sludge and a dehydrated separated liquid; a phosphorus supplying means for supplying phosphorus to at least a portion of the dehydrated separated liquid so that the phosphorus concentration is 0.7 mg / L or less per BOD of 100 mg / L; a biological treatment tank for subjecting the dehydrated separated liquid after the phosphorus supply to a biological treatment using a non-blocking biofilm method including at least one of a trickling filter method, a fluidized carrier method, a rotating disk method, and a fixed bed method; a dilution tank for diluting the biologically treated water obtained by the biological treatment so that the water meets the sewage discharge standards; A water treatment device comprising:

2. 2. The water treatment device according to claim 1, further comprising a storage tank for storing the dehydrated separated liquid obtained after dehydrating the water to be treated, the water containing at least one of the septic tank sludge and the sewage sludge, and the phosphorus supplying means dispenses the septic tank sludge and the sewage sludge into the dehydrated separated liquid in the storage tank.

3. 3. The water treatment device according to claim 1, further comprising a step of supplying an iron-based or aluminum-based flocculant during dehydration of the water to be treated.

4. The biological treatment tank has a BOD load of 0.5 to 5.0 kg-BOD / m 3 The water treatment device according to any one of claims 1 to 3, wherein the biological treatment tank is a biological treatment tank using a fluidized carrier method in which the biological treatment is performed at a temperature of 0.1 to 1.5°C.

5. The water treatment device according to any one of claims 1 to 4, characterized in that a membrane carrier having a structure in which the dehydration separated liquid and oxygen permeate opposite each other across a membrane surface is arranged in the biological treatment tank in which the biological treatment is performed using the biofilm method based on the trickling bed method, the membrane carrier comprises a support and a membrane supported by the support, the membrane has a loop shape that covers the support, the dehydration separated liquid permeates from the outer surface of the membrane, the oxygen permeates from a space formed on the inner surface of the membrane to the outer surface of the membrane, and an opening is formed in the membrane for discharging sludge peeling off from the inner surface of the membrane to the outside of the space.

6. An inflow means for inflowing the dewatered separated liquid stepwise into each of the biological treatment tanks including two or more stages of treatment tanks connected in series; a control means for controlling a step ratio of the dewatered separated liquid to be flowed into the biological treatment tank based on the volume load of the biological treatment tank and the water quality of the dewatered separated liquid or the biological treatment water; The water treatment device according to any one of claims 1 to 5, further comprising:

7. 7. The water treatment device according to claim 1, wherein the dilution tank dilutes the biologically treated water obtained in the biological treatment tank as it is without performing solid-liquid separation.

8. 8. The water treatment device according to claim 1, wherein the dehydrator separates the separated sludge having a moisture content of 70% or less from the dehydrated separated liquid.

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