Water treatment apparatus and water treatment method

Abstract

The present invention provides a water treatment method and a water treatment apparatus that enable efficient recovery of organic matter from organic wastewater while performing biological treatment of the water to be treated more efficiently and using compact equipment. [Solution] This water treatment apparatus comprises a first biological treatment unit 1 that performs a first biological treatment to remove organic matter contained in the water to be treated using a membrane separation activated sludge treatment apparatus 10, and a second biological treatment unit 2 that performs a second biological treatment to remove ammoniacal nitrogen and residual organic matter contained in the treated water from the first biological treatment unit 1 using a membrane aeration type biofilm reaction treatment apparatus 20.

Description

Technical Field

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

Background Art

[0002] A membrane separation activated sludge treatment apparatus (MBR) has the advantage of obtaining compact and clarified treated water with less solids, and is one of the biological treatment methods that is currently spreading. For example, in a high-load MBR, which is a type of MBR, most of the organic matter in the influent water is adsorbed and removed by activated sludge, so less energy is required for organic matter oxidation, the energy required for nitrification is substantially zero, and the generated sludge contains more organic matter than in the case of ordinary low-load MBR treatment. Therefore, high-load MBR is a promising technology from the viewpoint of being able to recover energy by methane fermentation of the organic matter contained in the generated sludge. In high-load MBR, since the treated water is filtered through a membrane, treated water with relatively good quality can be obtained. Non-Patent Document 1 describes a method of performing aerobic activated sludge treatment of organic wastewater at a high load using a membrane separation device.

[0003] There is known a membrane aeration type biofilm reaction treatment apparatus (MABR) that performs biological treatment by attaching microorganisms to the surface of an oxygen permeable membrane disposed in a treatment apparatus and supplying oxygen from the inner surface side of the oxygen permeable membrane. Japanese Unexamined Patent Application Publication No. 2023-49573 (Patent Document 1) describes performing biological treatment in a treatment apparatus equipped with an oxygen permeable membrane in a reaction tank after separating solid organic matter from organic wastewater using a rotary filter.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2023-49573 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, treatment using high-load MBR as described in Non-Patent Document 1 does not allow for nitrification, and the short wastewater retention time prevents complete decomposition of dissolved organic matter (BOD). As a result, ammoniacal nitrogen (NH4-N) and some dissolved BOD components in the raw water remain in the treated water. Treated water containing NH4-N and dissolved BOD is undesirable to discharge directly from the perspective of protecting the water quality of the discharge area. Therefore, further treatment is necessary to improve the water quality of the treated water.

[0007] The invention described in Patent Document 1 is a process in which relatively large solid particles are physically removed from the influent water by solid-liquid separation treatment using a rotary filter in the first stage. As a result, dissolved organic matter and NH4-N in the raw water remain in the influent water and are treated in the subsequent biological treatment using MABR. Depending on the water quality of the influent water, the subsequent biological treatment using MABR must treat influent water containing high concentrations of organic matter and NH4-N. Therefore, the nitrification efficiency is poor, the treatment takes a long time, and the energy consumption is high.

[0008] In view of the above issues, the present invention provides a water treatment method and a water treatment apparatus that can efficiently recover organic matter from organic wastewater while performing biological treatment of the water to be treated more efficiently and in a smaller facility. [Means for solving the problem]

[0009] As a result of diligent research to solve the above problems, the inventors of the present invention have found that it is useful to treat the water to be treated with MBR first, and then perform biological treatment with MABR.

[0010] Based on the above findings, the present invention, in one aspect, is a water treatment apparatus comprising a first biological treatment unit that performs a first biological treatment to remove organic matter contained in the water to be treated using a membrane separation activated sludge treatment unit, and a second biological treatment unit that performs a second biological treatment to remove ammonia nitrogen and residual organic matter contained in the treated water from the first biological treatment unit using a membrane aeration type biofilm reaction treatment unit.

[0011] In one embodiment, the water treatment apparatus according to the present invention is a first biological treatment in which 80% or more of the BOD in the water to be treated is removed.

[0012] In another embodiment, the water treatment apparatus according to the present invention uses a high-load membrane separation activated sludge method in which the first biological treatment is performed with a BOD / MLSS load of approximately 1.0 kg / kg / day or more and a sludge retention time of 1 day or less.

[0013] In yet another embodiment, the water treatment apparatus according to the present invention further comprises a solid-liquid separation unit for separating the treated water of a second biological treatment unit into solid and liquid components.

[0014] In yet another embodiment, the water treatment apparatus according to the present invention includes a water treatment supply path for supplying a portion of the water to be treated before it flows into the first biological treatment to a second biological treatment unit.

[0015] In yet another embodiment, the water treatment apparatus according to the present invention further comprises a nitrogen concentration meter for measuring the nitrogen concentration of the water to be treated in a second biological treatment unit, and a flow rate adjustment unit for adjusting the flow rate of the water to be treated supplied to the second biological treatment unit via a water to be treated supply path based on the measurement value of the nitrogen concentration meter.

[0016] In yet another embodiment, the water treatment apparatus according to the present invention further comprises a digester for methane fermentation treatment of excess sludge generated in the first biological treatment unit.

[0017] In yet another embodiment, the water treatment apparatus according to the present invention further comprises an excess sludge supply path for supplying excess sludge obtained in a second biological treatment unit to a digester.

[0018] In yet another embodiment, the water treatment apparatus according to the present invention further includes a filtrate supply path for supplying the dewatered filtrate of the digested sludge obtained in the digestion tank to the second biological treatment unit.

[0019] In yet another embodiment, the water treatment apparatus according to the present invention further includes an excess sludge return path for returning the excess sludge obtained in the second biological treatment unit to the first biological treatment unit.

[0020] In another aspect, the present invention provides a water treatment method comprising: a first biological treatment for removing organic substances contained in the water to be treated using a membrane separation activated sludge treatment apparatus; and a second biological treatment for removing ammonia nitrogen and residual organic substances contained in the treated water of the first biological treatment using a membrane aeration type biofilm reaction treatment apparatus.

Advantages of the Invention

[0021] According to the present invention, there can be provided a water treatment method and a water treatment apparatus capable of efficiently treating the water to be treated with a smaller-sized facility while efficiently recovering the organic components in the organic wastewater.

Brief Description of the Drawings

[0022] [Figure 1] It is a schematic diagram showing an example of the water treatment apparatus according to the embodiment of the present invention. [Figure 2] It is a schematic diagram showing a specific apparatus configuration example of the first biological treatment unit and the second biological treatment unit according to the embodiment.

Embodiments for Carrying Out the Invention

[0023] Embodiments of the present invention will be described below with reference to the drawings. In the following drawings, identical or similar parts are denoted by identical or similar reference numerals. The embodiments shown below are illustrative examples of devices and methods for realizing the technical idea of ​​this invention, and the technical idea of ​​this invention is not limited to the structure, arrangement, etc. of the components described below. In this specification, "%" means weight percent unless otherwise specified.

[0024] As shown in Figure 1, the water treatment apparatus according to an embodiment of the present invention comprises a first biological treatment unit 1 that performs a first biological treatment to remove organic matter contained in the water to be treated using a membrane bioreactor (MBR) 10, and a second biological treatment unit 2 that performs a second biological treatment to remove ammonia nitrogen and residual organic matter contained in the treated water from the first biological treatment unit 1 using a membrane bioreactor (MABR) 20.

[0025] By biologically treating the water to be treated with the MBR 10 provided in the first biological treatment unit 1, organic matter in the treated water can be removed more reliably and efficiently compared to solid-liquid separation by gravity sedimentation or cross-flow filtration such as a rotary filter.

[0026] The first biological treatment unit 1 preferably performs biological treatment to remove 80% or more, more preferably 90% or more, and even more preferably 95% or more of the organic matter, mainly BOD, from the water to be treated, and solid-liquid separation using a separation membrane. For example, the first biological treatment unit 1 can remove 80% or more, typically almost 100%, of the SS BOD from the water to be treated, and remove 50% or more of the soluble BOD from the water to be treated. The BOD, SS BOD, and soluble BOD in the water to be treated can be determined by calculating the BOD of the influent water and treated water using a test method compliant with JIS K0102 (2016).

[0027] In the first biological treatment unit 1, biological treatment and solid-liquid separation are performed to remove most of the BOD in the water to be treated. This allows for more efficient biological treatment in the second biological treatment unit 2, described later, to remove the NH4-N and BOD remaining in the treated water from the first biological treatment unit 1.

[0028] The second biological treatment unit 2, which uses MABR20, has a relatively high nitrification efficiency, allowing for more efficient and stable treatment of water containing organic matter in a compact facility. Furthermore, by controlling the conditions in the first biological treatment unit 1 so that the BOD in the treated water is removed to an appropriate concentration beforehand, the nitrification and denitrification treatment in the second biological treatment unit 2 can be carried out efficiently and stably over a long period of time.

[0029] As an MBR capable of removing 80% or more of organic matter, mainly BOD, from the water to be treated and efficiently recovering energy, a high-load membrane separation activated sludge treatment device (hereinafter also referred to as "high-load MBR") is particularly suitable.

[0030] As a high-load MBR, a high-load MBR is preferred for biological treatment using a high-load membrane separation activated sludge method, where the BOD / MLSS load is 1.0 kg / kg / day or more, the sludge retention time is 1 day or less, and the treated water is biologically treated. Preferred treatment conditions for a high-load MBR are a BOD / MLSS load of 1.0 to 3.0 kg / kg / day, and more preferably 1.0 to 2.0 kg / kg / day. The MLSS can be measured using a general MLSS meter or the like.

[0031] The CODcr / SS load for the first biological treatment is preferably 2.0 to 6.0 kg / kg / day, and more preferably 2.0 to 4.0 kg / kg / day. The SS and CODcr in the treated water can be measured by a test method in accordance with JIS K0102 (2016).

[0032] When recovering energy using excess sludge generated in the first biological treatment, it is preferable to adsorb as much dissolved BOD and colloidal BOD in the treated water as possible onto the activated sludge and recover it as excess sludge, and then perform methane fermentation on this excess sludge. However, some degree of oxidative decomposition of organic matter by the activated sludge is unavoidable.

[0033] In order to more efficiently recover organic matter in the treated water into the excess sludge and recover it as energy, the sludge retention time (SRT) of the first biological treatment is preferably within 1 day, and more preferably within 0.5 days. The hydraulic retention time (HRT) of the first biological treatment is preferably around 0.5 to 2 hours, and more preferably around 1 hour. The MLSS of the first biological treatment is preferably 1000 to 10000 mg / L, and more preferably 2000 to 5000 mg / L.

[0034] Figure 2 is a schematic diagram showing the case where a high-load MBR is applied as the MBR10 of the first biological processing unit 1. The MBR10 is equipped with a membrane module 11 in the treatment tank that has a separation membrane made of, for example, a microfiltration membrane (MF membrane) such as a hollow fiber membrane. The water to be treated is treated with activated sludge in the treatment tank, and suspended solids (SS or MLSS) in the water to be treated are filtered by the membrane module 11 to obtain treated water.

[0035] In high-load MBRs, it is preferable to supply air upward from a first blower 12 located at the bottom of the membrane module 11 towards the membrane module 11, as shown in Figure 2, in order to adjust the MLSS within the high-load MBR and suppress membrane fouling of the membrane module 11. It is preferable that the dissolved oxygen content (DO) of the water to be treated be 0.1 to 1.0 mg / L, preferably 0.2 to 0.5 mg / L, and that air be supplied upward from the first blower 12 towards the membrane module 11 to aerate the inside of the tank.

[0036] The treated water, separated into solid and liquid components by the membrane module 11, is supplied to the second biological treatment unit 2 via the extraction pipe 15 connected to the membrane module 11. Excess sludge generated in the high-load MBR is supplied to the digester tank 4 shown in Figure 1 via the sludge extraction pipe 16 connected to the bottom of the treatment tank. If the sludge concentration of the excess sludge is low (for example, 0.3% or less), a sludge thickening device may be connected to the sludge extraction pipe 16.

[0037] The MBR10 may be equipped with measuring devices 13 for measuring water quality information of the water to be treated within the MBR10. The measuring devices 13 may include a flow meter for measuring the inflow rate of the water to be treated, a thermometer for measuring the temperature of the water to be treated, a DO meter for measuring the DO of the water to be treated, a BOD meter for measuring the organic matter concentration, an MLSS meter for measuring activated sludge suspended solids, a nitrogen concentration meter for measuring nitrogen (ammonia nitrogen, nitrate nitrogen, total nitrogen) concentration, and the like.

[0038] The measuring device 13 is connected to the control device 8. Based on the measurement results of the measuring device 13, the control device 8 may adjust the flow rate of water to be treated into the first biological processing unit 1 using a flow rate adjustment unit 17 provided in the piping 18 that brings the water to be treated into the first biological processing unit 1. Although not shown, the water treatment apparatus according to this embodiment includes a measuring device (not shown) for measuring the water quality of the water to be treated flowing into the first biological processing unit 1, and the control device 8 may adjust the flow rate of water to be treated into the first biological processing unit 1 according to the water quality of the water to be treated.

[0039] For example, the control device 8 may control the amount of air supplied by the first blower 12 based on the measurement results of the MLDO concentration in the MBR 10 so that the MLDO concentration becomes a predetermined value (for example, about 0.5 mg / L). This makes the first biological treatment more efficient.

[0040] The treated water from the first biological treatment unit 1 has, for example, a BOD of 5 to 15 mg / L, more preferably 10 mg / L or less, and even more preferably 7 mg / L or less, with dissolved BOD accounting for 95% or more of that. The treated water CODcr has, for example, 20 to 40 mg / L, more preferably 30 mg / L or less, and even more preferably 20 mg / L or less, with dissolved CODcr accounting for 95% or more of that. Since the MBR 10 provided in the first biological treatment unit 1 cannot be expected to remove ammoniacal nitrogen or some dissolved BOD, ammoniacal nitrogen and some dissolved BOD remain in the treated water.

[0041] The second biological treatment unit 2 receives the treated water from the first biological treatment unit 1 as the water to be treated and performs biological treatment to remove ammoniacal nitrogen and residual organic matter contained in the water to be treated. As shown in Figure 2, the second biological treatment unit 2 is equipped with a MABR 20. The MABR 20 is equipped with an oxygen permeable membrane module 21 inside the treatment tank, which has an oxygen permeable membrane for biological treatment of ammonia and organic matter in the treated water by attaching microorganisms in the treated water to it.

[0042] The oxygen permeable membrane can consist of an oxygen permeable membrane composed of a bundle of hollow fiber membranes that allow oxygen to pass through, and a housing that accommodates the oxygen permeable membrane. The oxygen permeable membrane may be in the shape of a flat membrane or a spiral. Multiple oxygen permeable membrane modules 21 may be arranged in the treatment tank.

[0043] A microbial layer (biofilm layer) is formed on the surface of the oxygen permeable membrane by the attachment of microorganisms contained in the treated water. Typically, oxygen-containing gases such as oxygen or air are supplied to the inner surface of the oxygen permeable membrane module 21 from above. The oxygen permeable membrane module 21 allows oxygen to permeate from the inner surface to the surface where the microbial layer is formed. The oxygen permeable membrane can deliver oxygen to the microbial layer through an oxygen concentration gradient. MABR using such an oxygen permeable membrane can reduce the power required for oxygen supply compared to conventional activated sludge treatments that use aeration equipment to aerate the tank.

[0044] A second blower 22 capable of dissipating air from the oxygen permeable membrane module 21 may be connected to the lower part of the oxygen permeable membrane module 21. In the microbial layer formed on the surface of the oxygen permeable membrane of the oxygen permeable membrane module 21, nitrification and denitrification treatment of the water to be treated proceeds, and ammonia such as ammoniacal nitrogen and nitrogen such as nitrate nitrogen and nitrite nitrogen in the water to be treated are oxidized and reduced. The exhaust gas generated by the nitrification and denitrification treatment is discharged from the top of the oxygen permeable membrane module 21. The treated water separated into solid and liquid components in the oxygen permeable membrane module 21 is supplied to the solid-liquid separation section 3 via the extraction pipe 25 connected to the MABR 20. The excess sludge generated in the MABR 20 is supplied to the digester 4 in Figure 1 via the excess sludge supply route 26, such as a pipe connected to the bottom of the treatment tank. Alternatively, a portion of the excess sludge generated in the MABR 20 may be supplied to the sludge treatment section 6, or returned to the first biological treatment section 1 via an excess sludge return route (not shown).

[0045] MABR20 may be equipped with measuring devices 23 for measuring water quality information of the water to be treated within MABR20. The measuring devices 23 may include a flow meter for measuring the inflow rate of the water to be treated, a thermometer for measuring the temperature of the water to be treated, a DO meter for measuring the DO of the water to be treated, a BOD meter for measuring the organic matter concentration, a nitrogen concentration meter for measuring nitrogen (ammonia nitrogen, nitrate nitrogen, total nitrogen) concentration, pH, alkalinity, etc.

[0046] MABR20 may further include a supply unit 24 for supplying substrates such as methanol as an alkali source necessary for nitrification or a hydrogen donor necessary for denitrification. The supply unit 24 and the measuring device 23 are connected to the control device 8. Based on the measurement results from the measuring device 23, the control device 8 controls the supply unit 24 to supply an appropriate amount of alkali source or substrate from the supply unit 24 so that a stable nitrification-denitrification reaction can be obtained in MABR20.

[0047] If the removal of BOD (soluble BOD) from the water to be treated progresses too far in the first biological treatment unit 1, there is a possibility that the hydrogen donor required for the denitrification process of MABR 20 in the second biological treatment unit 2 will be insufficient. The water treatment device according to the first embodiment preferably further includes a water to be treated supply path 27 for supplying a portion of the water to be treated before it flows into the first biological treatment to the second biological treatment unit 2. By supplying the water to be treated supplied from the water to be treated supply path 27 to the second biological treatment unit 2 via the water to be treated supply path 27 instead of methanol supplied from the replenishment unit 24, the denitrification reaction in the second biological treatment unit 2 can be promoted by utilizing the substrate contained in the water to be treated, thereby reducing the amount of chemicals supplied from the replenishment unit 24 and enabling more efficient biological treatment.

[0048] In one embodiment, the control device 8 controls a flow rate adjustment unit 17 that introduces the water to be treated into the water to be treated supply path 27. Depending on the measurement results from the measuring device 23, if it is necessary to further promote the denitrification reaction in the second biological processing unit 2, for example, the control device 8 can supply the water to be treated from the water to be treated supply path 27 to the second biological processing unit 2. For example, if the measuring device 23 is a nitrogen concentration meter, it is preferable that the control device 8 supplies the water to be treated into the second biological processing unit 2 using a nitrogen concentration meter that measures the nitrogen concentration of the water to be treated in the second biological processing unit, and a flow rate adjustment unit 17 that adjusts the flow rate of the water to be treated supplied to the second biological processing unit 2 based on the measurement value of the nitrogen concentration meter.

[0049] The second biological treatment conditions are, but are not limited to, the amount of oxygen supplied to the oxygen permeable membrane module 21, which is 0.05 to 0.15 NL / (m³). 2 ·min), preferably about 0.1NL / (m 2 The air is supplied at a rate of 1 min(m), the air pressure is set to 3-5 kPa, preferably about 4 kPa, and the membrane area load (CODcr membrane area load) is set to 5-15 g / m². 2 It is preferable to do this in d), with approximately 10 g / (m 2 It is more preferable to carry out the procedure in d). Also, the oxygen supply rate per unit area (OTR) is not limited to the following, but for example, 5 to 12 g-O2 / m 2 / d, the nitrification rate per membrane area is 1-3 g-N / m2 It can be set to / d.

[0050] The hydrological residence time (HRT) for the second biological treatment is not uniform, depending on the water quality conditions and the design of the MABR, but it is reasonable to install it in a reaction tank with an HRT of 2 to 4 hours. Aeration from the second blower 22 is performed intermittently to suppress blockage of the oxygen permeable membrane module 21. Aeration from the second blower 22 may also be performed at a low level to prevent the DO in the treatment tank from rising too high. The DO in the MABR 20 is controlled to be approximately 0.5 to 1.5 mg / L in the water to be treated.

[0051] The solid-liquid separation unit 3 uses the treated water from the second biological treatment unit 2, supplied via the extraction pipe 25, as the water to be treated and performs solid-liquid separation, for example, by sand filtration or a sedimentation tank, to obtain treated water. If the biological treatment by the second biological treatment unit 2 is sufficiently performed and the treated water from the second biological treatment unit 2 meets the predetermined water quality standards, the solid-liquid separation unit 3 may be omitted.

[0052] As shown in Figure 1, the digester 4 processes the excess sludge generated in the first biological processing unit 1 using anaerobic microorganisms for methane fermentation. The digester 4 is connected to an excess sludge supply path 26 that supplies excess sludge obtained in the second biological processing unit 2 to the digester 4. According to this embodiment, by connecting the excess sludge supply path 26 to the digester 4, the amount of organic matter supplied into the digester 4 increases compared to the case where excess sludge from the second biological processing unit 2 is not supplied, so that more digester gas such as methane gas can be generated from the water being treated. The digester gas generated in the digester 4 can be used as electrical energy and thermal energy in the digester gas power generation unit 5. Furthermore, by using the heat generated by the combustion of the digester gas generated in the digester 4 to heat the digester 4 and the second biological processing unit 2, it is possible to improve the treatment efficiency of nitrification and denitrification treatment in winter when the water temperature drops.

[0053] The digested sludge generated in the digester 4 is supplied to the sludge processing unit 6. In the sludge processing unit 6, the digested sludge undergoes dewatering, drying, and fertilizer treatment. For example, the digested sludge is dewatered to a predetermined moisture content using a dewatering machine. The dewatered sludge is then dried further to a lower moisture content using a dryer, if necessary. The dewatered sludge and dried sludge can be used as fertilizer, etc.

[0054] The dewatered filtrate of the digested sludge generated in the digester 4 contains organic matter such as BOD, ammonia, and dissolved methane, which can be processed in the second biological treatment unit 2. Therefore, in addition to using the dewatered sludge as fertilizer, this dewatered filtrate can be reused as a substrate or alkaline agent to promote nitrification and denitrification treatment in the second biological treatment unit 2. In the water treatment apparatus according to this embodiment, it is preferable to further include a dewatered filtrate supply path 67 that supplies the dewatered filtrate of the digested sludge generated in the sludge treatment unit 6 to the second biological treatment unit 2.

[0055] (Water treatment method) Water treatment can be performed using the water treatment apparatus according to an embodiment of the present invention. The water treatment method according to an embodiment of the present invention includes a first biological treatment using MBR10 to remove organic matter contained in the water to be treated, and a second biological treatment using MABR20 to remove ammonia nitrogen and residual organic matter contained in the treated water from the first biological treatment.

[0056] More specifically, the water to be treated is first introduced into the first biological treatment unit 1. Then, using the MBR 10, a first biological treatment is performed to remove organic matter contained in the water to be treated, preferably using an MBR, preferably a high-load MBR. After that, a second biological treatment is performed using the MBAR 20 to remove ammoniacal nitrogen and residual organic matter contained in the treated water from the first biological treatment unit 1. The treated water from the second biological treatment is subjected to solid-liquid separation as needed to obtain treated water.

[0057] According to the water treatment apparatus and water treatment method according to the embodiment of the present invention, in both the first biological treatment and the second biological treatment, the water to be treated is biologically treated by microorganisms present in the treatment tank. Of the dissolved organic matter in the water to be treated, some is adsorbed by the activated sludge in the MBR10, some is removed, and the remainder flows out into the treated water. Almost all of the suspended solids (SS) and almost all of the colloidal particles in the water to be treated are adsorbed by the activated sludge and can be appropriately removed in the first biological treatment. Therefore, the water quality of the solid-liquid separated liquid is clearer than that of a typical solid-liquid separated liquid using a rotary filter or the like. In the subsequent second biological treatment, it is sufficient to treat wastewater mainly consisting of NH4-N and some dissolved BOD. Since the second biological treatment section 2 utilizes the MABR20, the nitrification rate is fast and aeration other than membrane washing is not required, so the energy consumption required for treatment can be reduced.

[0058] Furthermore, according to the water treatment apparatus and water treatment method according to the embodiment of the present invention, the first biological treatment unit 1 is equipped with an MBR 10, and this MBR 10 is capable of maintaining a high concentration of MLSS. Therefore, according to the water treatment apparatus and water treatment method according to the embodiment of the present invention, organic matter in the water to be treated can be efficiently removed regardless of the water quality of the water to be treated that flows into the first biological treatment unit 1.

[0059] The MBR10 membrane is typically a microfiltration membrane, which has the effect of stabilizing the microbial community acclimated within the MABR of the second biological treatment unit 2. Therefore, by combining the treatment with MBR10 in the first biological treatment unit 1 and the treatment with MABR20 in the second biological treatment unit 2, it becomes possible to perform biological treatment more stably over a longer period.

[0060] Furthermore, according to the embodiment of the present invention, by using a high-load MBR as the MBR, the amount of organic matter that can be recovered from a unit volume of wastewater is greater than that of a typical low-load MBR, thus increasing the amount of digester gas generated in the digester tank 4. As a result, the energy contained in the organic matter can be recovered from the treated water containing organic matter through methane fermentation, and at the same time, the treated water can be biologically treated more efficiently and with a smaller facility. In this embodiment, the use of a high-load MBR is shown as a preferred example, but in cases such as combined sewer systems where the raw water is diluted with rainwater for a certain period during the rainy season, it is of course possible to operate with a low-load MBR such that the BOD / MLSS load is about 0.4 kg / kg / day or less and the sludge retention time exceeds about 2 days.

[0061] (Other embodiments) Although the present invention has been described by the embodiments described above, the descriptions and drawings that constitute part of this disclosure should not be understood as limiting the invention. This disclosure is not limited to the embodiments described above, and its components can be combined and modified to embody it without departing from its spirit.

[0062] The water treatment apparatus and water treatment method according to this embodiment are particularly suitable for treating general sewage with a raw water BOD concentration of about 150 to 250 mg / L, but can also be applied to organic wastewater with a BOD concentration of less than 150 mg / L. For example, if the raw water has a low BOD concentration of several tens of mg / L, but the NH4-N concentration in the raw water is high, the entire amount of water to be treated before it flows into the first biological treatment unit 1 via the water to be treated supply path 27 may be supplied to the second biological treatment unit 2. In this case, simple solid-liquid separation equipment such as a gravity sedimentation device, an ultra-fine screen, or a membrane filtration device may be placed in the water to be treated supply path 27. [Explanation of symbols]

[0063] 1: First Biology Department 2: Second Biology Section 3: Solid-liquid separation section 4: Digestion tank 5: Digestive Gas Power Generation Department 6: Sludge Treatment Section 8: Control device 10: Membrane-based activated sludge treatment system (MBR) 11: Membrane Module 12: First blower 13: Measuring device 15: Extracted Piping 16: Sludge extraction piping 17:Flow rate adjustment part 18: Piping 20: Membrane-ventilated biomembrane reaction apparatus (MABR) 21: Oxygen permeable membrane module 22: Second blower 23: Measuring device 24: Supply Department 25: Extracted Piping 26: Excess sludge supply route 27: Water supply route for treated water 67: Dehydrated filtrate supply route

Claims

1. A first biological treatment unit that performs a first biological treatment to remove organic matter contained in the water to be treated using a membrane separation activated sludge treatment device, A second biological treatment unit, using a membrane-permeable biofilm reaction apparatus, performs a second biological treatment to remove ammonia nitrogen and residual organic matter contained in the treated water of the first biological treatment unit. A water treatment device equipped with the following features.

2. The water treatment apparatus according to claim 1, wherein the first biological treatment is a biological treatment that removes 80% or more of the BOD in the water to be treated.

3. The water treatment apparatus according to claim 1, wherein the first biological treatment uses a high-load membrane separation activated sludge method in which the water to be treated is biologically treated with a BOD / MLSS load of approximately 1.0 kg / kg / day or more and a sludge retention time of 1 day or less.

4. The water treatment apparatus according to any one of claims 1 to 3, further comprising a solid-liquid separation unit for separating the treated water of the second biological treatment unit from a solid-liquid state.

5. The water treatment apparatus according to any one of claims 1 to 3, further comprising a water treatment supply path for supplying a portion of the water to be treated before it flows into the first biological treatment to the second biological treatment.

6. A nitrogen concentration meter for measuring the nitrogen concentration of the treated water in the second biological processing unit, A flow rate adjustment unit adjusts the flow rate of the water to be treated supplied to the second biological processing unit via the water to be treated supply path based on the measurement value of the nitrogen concentration meter, The water treatment apparatus according to claim 5, further comprising:

7. The water treatment apparatus according to any one of claims 1 to 3, further comprising a digester for methane fermentation treatment of excess sludge generated in the first biological treatment unit.

8. The water treatment apparatus according to claim 7, further comprising an excess sludge supply path for supplying excess sludge obtained in the second biological treatment unit to the digestion tank.

9. The water treatment apparatus according to claim 8, further comprising a dewatered filtrate supply path for supplying the dewatered filtrate of digested sludge obtained in the digester to the second biological treatment unit.

10. A first biological treatment is performed using a membrane separation activated sludge treatment device to remove organic matter contained in the water to be treated, A second biological treatment is performed using a membrane-fed biofilm reaction apparatus to remove ammonia nitrogen and residual organic matter contained in the treated water of the first biological treatment. A water treatment method that includes [a specific component].

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