Organic wastewater treatment method and organic wastewater treatment device

Abstract

To provide a treatment method of organic discharge water capable of reducing electric power needed for wastewater treatment of sewage water, discharge water, etc., and elevating fermentation efficiency of methane fermentation.SOLUTION: Disclosed is a treatment method of organic discharge water which is characterized by including the following steps A to C: step A of separating raw water to a solid W1 and a supernatant liquor W2 by using a filtration installation 1; step B of performing biological treatment of the solid W1 in an anaerobic membrane separator 2 by using an anaerobic digestion sludge containing anaerobic microorganisms and performing membrane separation of the anaerobic digestion sludge by using a membrane separator 3 to obtain a membrane transmission flow; and step C of performing aerobic treatment of the supernatant liquor W2 obtained in the step A by using a water spray filter bed installation 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for treating organic wastewater and an apparatus for treating organic wastewater. Regarding. [Background technology]

[0002] Aerobic treatment methods such as the activated sludge process are widely used as water treatment methods for treating organic matter-containing water, such as sewage and wastewater. Such aerobic activated sludge processes require equipment such as a blower for aeration, which requires power to operate, resulting in relatively large energy consumption.

[0003] In contrast, anaerobic treatment uses anaerobic digestion sludge, which does not require aeration to decompose organic matter, and can significantly reduce the energy demands for treatment and generate an energy source in the form of biogas, which can be used to transport water and for other processes. For this reason, from the perspective of reducing energy consumption, etc., anaerobic membrane separation (hereinafter also referred to as anaerobic MBR), which combines anaerobic treatment and membrane separation, is attracting attention.

[0004] The wastewater treatment system described in Patent Document 1 is an example of the anaerobic MBR method. The anaerobic MBR method described in Patent Document 1 will be described with reference to FIG. The wastewater treatment system 10 comprises a stage A (pre-membrane filtration system), a stage B (anaerobic MBR system), and an optional stage C (membrane filtration water treatment system). The Stage A pre-membrane filtration system includes a settling tank 12, a filtration unit feed pump 14, a filtration unit 16, a slurry pump 18, and a heat exchanger 20. Raw water is fed to the settling tank 12, where most of the particulate and colloidal matter in the wastewater settles to the bottom of the settling tank 12. The supernatant water from the settling tank 12 is fed to the filtration unit 16 using the filtration unit feed pump 14. The filtration unit 16 contains an MF or UF membrane, and a membrane permeate stream 24 is sent to Stage C, while a concentrate stream 26 is returned to the settling tank 12.

[0005] Meanwhile, the slurry in the settling tank 12 is sent to a heat exchanger 20, where it is heated, and then sent to the anaerobic MBR system in Stage B. The anaerobic MBR system includes an anaerobic bioreactor 30, a membrane filtration unit pump 32, and a membrane filtration unit 34, and is configured as an apparatus for anaerobic membrane separation (AnMBR). The anaerobic bioreactor 30 uses microorganisms (anaerobic bacteria) to break down the organic matter in the slurry to produce biogas.

[0006] The slurry from the anaerobic bioreactor 30 is pumped to a membrane filtration unit 34 using a membrane filtration unit feed pump 32. The membrane filtration unit 34 includes a filter 36 and separates the slurry into a membrane permeate stream 38 and a concentrate stream 40, with the concentrate stream 40 being returned to the anaerobic bioreactor 30 and the membrane permeate stream 38 being discharged as treated water. The permeate from the Stage A separation subsystem is optionally sent to the Stage C membrane filtration water treatment system, which passes through an algae photobioreactor 44 and a disinfection system 46 before being discharged as treated water. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2016 / 141369 Summary of the Invention [Problem to be solved by the invention]

[0008] The wastewater treatment system described in Patent Document 1 separates raw water into supernatant water and slurry in a settling tank, and the supernatant water undergoes membrane separation treatment in a pre-stage membrane filtration system in Stage A, while the slurry is treated in an anaerobic MBR. In this wastewater treatment system, the supernatant water in the settling tank is also subjected to membrane separation treatment, which poses a problem in that it requires a large amount of power for this membrane separation treatment.

[0009] An object of the present invention is to provide a method for treating organic wastewater that can reduce the power required for treating wastewater such as sewage and wastewater, and can also increase the fermentation efficiency of methane fermentation. [Means for solving the problem]

[0010] The present invention for solving the above problems is as described below. A method for treating organic wastewater, comprising the following steps A to C: Step A: A step of separating raw water into solids and supernatant liquid using a coarse filtration facility; Step B: a step of subjecting the solid fraction to biological treatment using an anaerobically digested sludge containing anaerobic microorganisms in an anaerobic membrane separation device, and simultaneously subjecting the anaerobically digested sludge to membrane separation using a membrane separation device to obtain a membrane permeate stream; and, Step C: A step of aerobically treating the supernatant obtained in step A using a trickling filter. [Effects of the Invention]

[0011] By using the method for treating organic wastewater of the present invention, raw water such as sewage or wastewater can be treated with low power consumption and the fermentation efficiency of methane fermentation can be increased. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram illustrating an outline of the organic wastewater treatment method of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an outline of a conventional organic wastewater treatment method. DETAILED DESCRIPTION OF THE INVENTION

[0013] The method for treating organic wastewater of the present invention comprises the following steps. Process A: A process in which raw water is separated into solids and supernatant liquid using a coarse filtration facility. Step B: A step of subjecting the solids to biological treatment using an anaerobic digestion sludge containing anaerobic microorganisms in an anaerobic membrane separation device, and simultaneously subjecting the anaerobically digested sludge to membrane separation using a membrane separation device to obtain a membrane permeate flow. and Step C: A step of aerobically treating the supernatant obtained in step A using a trickling filter.

[0014] Each of the steps A to C will be described below with reference to FIG. [Process A] Step A is a step in which raw water such as sewage or wastewater is subjected to solid-liquid separation in a rough filtration facility 1 into a solid content W1 and a supernatant liquid W2. (Rough filtration equipment) Roughing filtration equipment is a pretreatment facility installed primarily for the purpose of preventing the intrusion of wastewater and foreign matter into water treatment equipment. This facility recovers suspended organic matter as much as possible, increasing the amount of organic matter flowing into process B, while also reducing the organic matter load in process C. As the coarse filtration equipment, a granular filtration tank, a strainer, a screen filtration device, etc. can be used.

[0015] <Granular filtration tank> This is a type of filtration that uses granular filter media with a diameter of about 0.5 to 5 mm, and is usually operated with a filter layer thickness of about 0.3 to 1.5 m and a filtration rate of about 100 to 1000 m / d. Various filter media can be used, including sand, gravel, fiber filter media, and plastic filter media. The raw water, sewage treatment water, has a high concentration of suspended solids (SS) and a high BOD (biochemical oxygen demand). Therefore, by roughly filtering the water through a granular filter layer in a granular filter tank, the concentration of SS and the BOD are reduced, thereby pretreating the raw water, sewage treatment water.

[0016] <Strainer> A strainer is a device that contains a filter body (separation element) made of metal or synthetic resin and formed into a mesh, and separates and removes impurities from the water to be treated using the mesh of the separation element. The strainer, for example, has a cylindrical separation element (a mesh-like filter) with a bottom disposed inside, which separates the strainer into an outer raw water chamber and an inner filtered water chamber. Raw water is supplied to the raw water chamber, and filtered water that passes through the separation element is discharged from the filtered water chamber. The separation element may be made of punched metal, or may have a folded shape with repeated peaks and valleys on its circumferential surface. The material of the separating element of the strainer is not particularly limited, and metal, synthetic fiber, synthetic resin, etc. can be used. The opening size of the separating element of the strainer is not particularly limited, but is usually in the range of several hundred μm to several mm, preferably in the range of 100 μm to 1 mm.

[0017] <Screen filtration device> An example of a screen filtration device is an inclined screen filtration device, which allows raw water to flow down the surface of a screen installed at an angle, allowing the flowing water and fine contaminants to pass through, and allows coarse solids S that cannot pass through to slide down the surface of the screen toward the bottom end of the screen, separating the solid from the liquid.

[0018] [Process B] Step B is a step in which the solid fraction obtained in step A is treated by anaerobic membrane separation. In step B, the solid content W1 obtained in step A is supplied to an anaerobic membrane separation device 2, where it is subjected to biological treatment using anaerobically digested sludge containing anaerobic microorganisms, and a membrane permeate flow W3 is obtained from the anaerobically digested sludge using a membrane separation device 3. Methane gas is produced in the anaerobic membrane separation device 2, and this methane gas is sent to an appropriate methane utilization facility. Anaerobically digested sludge is also extracted from the anaerobic membrane separation apparatus 2, a portion of which is returned to the anaerobic membrane separation apparatus 2 as returned sludge W4, and the remainder is discharged to the outside of the system as excess sludge W5. In step A, raw water is filtered in a roughing filtration facility 1 to remove supernatant liquid W2, and only solids W1 are treated in the anaerobic membrane separation device 2, thereby reducing the amount of water treated in the anaerobic membrane separation device 2. This makes it possible to reduce the required membrane area of ​​the membrane separation device 3, and to increase the fermentation efficiency by maintaining a high sludge concentration.

[0019] The example shown in Figure 1 shows a submerged anaerobic membrane separation device in which the separation membrane is submerged in a biological reactor. However, the biological reactor and the separation membrane tank may be provided separately, and the anaerobically digested sludge that has been biologically treated in the biological reactor may be subjected to membrane separation treatment in the separation membrane tank.

[0020] [Process C] Step C is a step of aerobically treating the supernatant liquid W2 obtained in step A using a trickling filter bed equipment 4. By using the trickling filter equipment 4 for aerobic treatment, it is possible to reduce the power consumption.

[0021] (Trickling filter bed equipment) The trickling filter method is a type of biofilm method, in which a circular pond is filled with filter material such as crushed stone to a height of about 1.5 to 2 m, and the water to be treated is intermittently or continuously sprayed onto the surface of the filter material, causing a contact reaction with the biofilm formed on the surface of the filter material. The filter material is crushed stone or gravel with a diameter of 35 to 100 mm. There are two types of sprinkler systems: fixed and mobile. The mobile system includes a traveling girder system and a rotating system.

[0022] The rotary sprinkler system is a system in which a rotary manifold is attached to a fixed central cylinder, and reaction sprinkler nozzles are attached to the branch pipes, which are rotated while spraying water, allowing the water to be sprayed over the entire surface of the filter bed.

[0023] A girder-traveling sprinkler machine has a girder that travels on a sprinkler rail, and sprinkler pipes equipped with multiple sprinkler nozzles are suspended and supported on the girder.As the girder travels, water is sprayed from the sprinkler nozzles, allowing it to spray the entire surface of the filter bed.

[0024] In the present invention, a denitrification treatment step may be further provided. (Denitrification treatment) The denitrification treatment is a treatment for converting nitrogen components contained in the membrane permeate stream W3 obtained in step B and the filtrate W6 obtained in the trickling filter bed equipment 4 in step C into nitrogen gas. Examples of denitrification methods include the following methods (1) and (2). (1) A biological nitrification and denitrification method that includes a nitrification process and a denitrification process. In the nitrification process, nitrifying bacteria oxidize ammonia (NH4) in wastewater to nitrite (NO2) and then nitrate (NO3), and in the denitrification process, denitrifying bacteria reduce nitrate and nitrite to nitrogen gas. (2) Using anammox bacteria, ammonia nitrogen (NH4 + ) and nitrite nitrogen (NO2 - ) directly converted into nitrogen gas (N2) by the anammox reaction method The anammox reaction method eliminates the need to completely decompose ammonia into nitrate during the nitrification process, enabling a significant reduction in power consumption. Furthermore, because anammox bacteria produce less excess sludge, it also enables a significant reduction in sludge treatment costs.

[0025] The anammox reaction is a reaction in which anammox bacteria use NH4-N and NO2-N as substrates to produce N2 under anaerobic conditions, and is represented by the following reaction formula: (Reaction equation) 1.0NH4 + +1.32NO2- +0.066HCO3 - +0.13H + → 1.02N2+0.26NO3 - +0.066CH2O 0.5 N 0.15 +2.03H2O

[0026] The present invention relates to the following method for treating organic wastewater (1), and includes the following embodiments (2) to (8). (1) A method for treating organic wastewater, comprising the following steps A to C: Step A: A step of separating raw water into solids and supernatant liquid using a coarse filtration facility; Step B: a step of subjecting the solid fraction to biological treatment using an anaerobically digested sludge containing anaerobic microorganisms in an anaerobic membrane separation device, and simultaneously subjecting the anaerobically digested sludge to membrane separation using a membrane separation device to obtain a membrane permeate stream; and, Step C: A step of aerobically treating the supernatant obtained in step A using a trickling filter. (2) The method for treating organic wastewater according to (1) above, further comprising the following step D: Step D: A step of denitrifying the nitrogen components in the membrane permeate stream obtained in Step B by an anaerobic ammonium oxidation reaction. (3) The method for treating organic wastewater according to (2) above, wherein the step D is carried out in an anammox tank. (4) A coarse filtration facility that performs coarse filtration of raw water to separate it into solids and supernatant liquid; an anaerobic membrane separation device that anaerobically treats the solids obtained in the rough filtration facility using anaerobically digested sludge and separates the anaerobically digested sludge into a membrane permeate stream and a concentrated stream using a membrane separation device; a trickling filter bed facility for aerobic treatment of the supernatant obtained in the coarse filtration facility; An organic wastewater treatment device comprising: (5) The organic wastewater treatment device according to (4) above, wherein the anaerobic membrane separation device is provided in a biological reaction tank for anaerobic treatment. (6) The anaerobic membrane separation device is an organic wastewater treatment device according to (4) above, which comprises a biological reactor tank for anaerobically treating sludge, and a membrane separation tank for separating the anaerobically digested sludge in the biological reactor tank through membrane separation into a membrane permeate stream and a concentrated stream. (7) The organic wastewater treatment device according to any one of (4) to (6) above, further comprising a denitrification device that denitrifies nitrogen components in the membrane permeate stream obtained in the anaerobic membrane separation device by an anaerobic ammonium oxidation reaction. (8) The organic wastewater treatment device according to (7) above, wherein the denitrification device is an anammox reaction treatment device. [Explanation of symbols]

[0027] (Figure 1) 1 Rough filtration equipment 2. Anaerobic membrane separation device 3 Membrane separation equipment 4 Trickling filter equipment 5 Denitrification equipment W1 solids W2 supernatant W3 membrane permeation flow W4 Returned sludge W5 Excess sludge W6 filtered water (Figure 2) 10 Wastewater treatment system 12 Settling tank 14 Filtration unit supply pump 16 Filtration unit 18 Slurry Pump 20 Heat exchanger 24 Membrane permeation flow 26 Concentrate stream 30 Anaerobic Bioreactor 32 Membrane filtration unit pump 34 Membrane filtration unit 36 filters 38 Membrane permeation flow 40 Concentrated stream 44 Algae Photobioreactor 46 Disinfection System

Claims

1. A method for treating organic wastewater, comprising the following steps A to C: Step A: A step of separating raw water into solids and a supernatant using a coarse filtration facility; Step B: A step of subjecting the solid fraction to biological treatment using an anaerobic digestion sludge containing anaerobic microorganisms in an anaerobic membrane separation device, and simultaneously subjecting the anaerobically digested sludge to membrane separation using a membrane separation device to obtain a membrane permeate stream; and, Step C: A step of aerobically treating the supernatant obtained in step A using a trickling filter bed equipment.

2. The method for treating organic wastewater according to claim 1, further comprising the following step D: Step D: A step of denitrifying the nitrogen components in the membrane permeate stream obtained in Step B by an anaerobic ammonium oxidation reaction.

3. The method for treating organic wastewater according to claim 2, wherein the step D is carried out in an anammox tank.

4. A coarse filtration facility that performs coarse filtration on raw water to separate it into solids and a supernatant liquid; an anaerobic membrane separation device that anaerobically treats the solids obtained in the rough filtration facility using anaerobically digested sludge and separates the anaerobically digested sludge into a membrane permeate stream and a concentrated stream using a membrane separation device; a trickling filter bed facility for aerobic treatment of the supernatant obtained in the coarse filtration facility; An organic wastewater treatment device comprising:

5. 5. The organic wastewater treatment device according to claim 4, wherein the anaerobic membrane separation device is provided in a biological reaction tank for anaerobic treatment.

6. 5. The organic wastewater treatment device according to claim 4, wherein the anaerobic membrane separation device comprises a biological reaction tank for anaerobically treating sludge, and a membrane separation tank for separating the anaerobically digested sludge in the biological reaction tank through membrane separation into a membrane permeate stream and a concentrated stream, the membrane separation tank being provided separately.

7. 5. The organic wastewater treatment device according to claim 4, further comprising a denitrification device that denitrifies nitrogen components in the membrane permeate stream obtained in the anaerobic membrane separation device by an anaerobic ammonium oxidation reaction.

8. The organic wastewater treatment device according to claim 7, wherein the denitrification device is an anammox reaction treatment device.

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