AOA-MBR sewage treatment system

Abstract

The utility model relates to the technical field of sewage treatment, and discloses an AOA-MBR sewage treatment system, which comprises an AOA reaction tank, an MBR membrane tank, a reflux unit and an output unit, the reflux unit is used for refluxing sludge in the MBR membrane tank into the AOA reaction tank, and a membrane filtration area and a pre-precipitation area which are communicated up and down are arranged in the MBR membrane tank; the pre-precipitation area is used for primarily separating a mud-water mixture entering the MBR membrane tank; and the membrane filtration area is used for separating the mud-water mixture subjected to primary separation again. According to the system, most nitrate in a sludge-water mixture is converted into nitrogen in an anoxic environment of the AOA reaction tank, the content of nitrate is low, sludge subjected to primary separation does not pass through a membrane filtration area and is not subjected to an aeration oxygenation process, the content of dissolved oxygen and nitrate is low, and after the sludge flows back to the anoxic / anaerobic environment of the AOA reaction tank, the content of dissolved oxygen and nitrate in the sludge is low. The method is very beneficial to maintaining and guaranteeing the anoxic environment and the anaerobic environment in the AOA reaction tank, and the nitrogen and phosphorus removal effect is guaranteed.

Description

TECHNICAL FIELD

[0001] The utility model relates to sewage treatment technical field, concretely relates to a kind of AOAMBR sewage treatment system. BACKGROUND

[0002] AOA process is the abbreviation of anaerobic (A)-oxygen (O)-anoxic (A) process, which adopts sludge double reflux mode by omitting internal reflux, and it converts COD of influent into intracellular carbon source in anaerobic section, and encloses these intracellular carbon source in the body of microorganism. After passing through the oxygen zone, the intracellular carbon source is used for denitrification in the anoxic zone, which can simultaneously remove nitrogen and phosphorus, and reduce the consumption of external carbon source.

[0003] MBR process, i.e. membrane bioreactor, is a sewage treatment technology combining membrane separation technology with biological treatment. It realizes the degradation of organic matter and solid-liquid separation in the same equipment by combining membrane element with biological reactor.

[0004] CN116477776A discloses a front phosphorus removal rear endogenous denitrification coupled MBR sewage treatment system and process, which mainly includes a front phosphorus removal unit, a rear endogenous denitrification unit and a sludge reflux unit. The effluent from the sand trap enters the flocculation and sedimentation phosphorus removal unit for phosphorus removal. Then the supernatant enters the rear endogenous denitrification unit, and the carbon source is absorbed by the anaerobic bacteria in the anaerobic tank. In the dynamic aerobic tank, the dynamic and accurate nitrification is carried out with the cooperation of detection instruments and control equipment, and then the rear endogenous denitrification is carried out in the anoxic tank, so as to achieve deep denitrification. The effluent from the anoxic tank and the sludge enter the MBR membrane tank and the sludge reflux unit, and a double reflux system is adopted to maximize the function of the anaerobic zone, or a pre-anaerobic zone is set to shunt the influent and reduce the influence of high dissolved oxygen in the MBR membrane tank on denitrifying bacteria.

[0005] The above technical solution solves the problems of low denitrification efficiency of traditional front denitrification, contradiction between post-biological phosphorus removal and denitrification sludge age, high suspended solids in biochemical effluent and inability to selectively increase sludge concentration in winter. However, due to high dissolved oxygen in the MBR membrane tank, the reflux is relatively large, and the dissolved oxygen and nitrate in the reflux liquid are relatively high, which destroys the anaerobic environment and anoxic environment and affects the conditions and functions of the AOA process. UTILITY MODEL CONTENT

[0006] The present application aims to solve the above problems, and provides an AOA-MBR sewage treatment system. The system is provided with a membrane filtration zone and a pre-sedimentation zone in the MBR membrane tank, so that most of the sludge in the sludge-water mixture entering the MBR membrane tank is preliminarily separated in the pre-sedimentation zone and deposited at the bottom of the pre-sedimentation zone, and then is returned to the AOA reaction tank through the return unit. The system makes full use of the fact that most of the nitrate in the sludge-water mixture has been converted into nitrogen in the anoxic environment of the AOA reaction tank, and the nitrate is low. The preliminarily separated sludge does not pass through the membrane filtration zone and does not pass through the aeration oxygenation process, so the dissolved oxygen and the nitrate are also low. After being returned to the anoxic / anaerobic environment of the AOA reaction tank, it is very beneficial to maintaining and protecting the anoxic and anaerobic environments in the AOA reaction tank, and ensures the effect of denitrification and phosphorus removal.

[0007] To achieve the above object, the present application provides the following technical solutions:

[0008] An AOA-MBR sewage treatment system, comprising an AOA reaction tank, an MBR membrane tank in communication with the AOA reaction tank, a return unit, and an output unit. The return unit is used for returning sludge in the MBR membrane tank to the AOA reaction tank. The MBR membrane tank is provided with a membrane filtration zone and a pre-sedimentation zone in communication with each other. The outlet end of the AOA reaction tank is located between the membrane filtration zone and the pre-sedimentation zone.

[0009] The pre-sedimentation zone is used for preliminarily separating the sludge-water mixture entering the MBR membrane tank, so that part of the sludge in the sludge-water mixture is deposited and concentrated, and then is returned to the AOA reaction tank through the return unit.

[0010] The membrane filtration zone is used for re-separating the preliminarily separated sludge-water mixture, and the separated water is discharged through the output unit.

[0011] Preferably, the AOA reaction tank comprises an anaerobic zone, a first switching zone, an aerobic zone, a second switching zone, and an anoxic zone in sequence.

[0012] The anaerobic zone is provided with a first stirring device. The first switching zone is provided with a second stirring device and a first aeration device for switching between anaerobic and aerobic. The aerobic zone is provided with a second aeration device. The second switching zone is provided with a third stirring device and a third aeration device for switching between aerobic and anoxic. The anoxic zone is provided with a fourth stirring device. The return unit is used for returning the sludge in the MBR membrane tank to the anaerobic zone and the second switching zone or the anoxic zone.

[0013] Preferably, the return unit comprises a first control pipeline for controlling the return of the sludge in the MBR membrane tank to the anaerobic zone, a second control pipeline for controlling the return of the sludge in the MBR membrane tank to the anoxic zone, and a third control pipeline for controlling the return of the sludge in the MBR membrane tank to the second switching zone.

[0014] Preferably, the third control pipeline is connected at the feed inlet of the second switching zone.

[0015] Preferably, the first control pipeline comprises a first backflow pipe, a first backflow pump arranged on the first backflow pipe, and a first backflow valve; the second control pipeline comprises a second backflow pipe, a second backflow pump arranged on the second backflow pipe, and a second backflow valve; the third control pipeline comprises a third backflow pipe and a third backflow valve arranged on the third backflow pipe, and the third backflow pipe and the second backflow pipe are communicated.

[0016] The second backflow valve, the third backflow valve, and the third aeration device and the third stirring device are linked.

[0017] Preferably, a guide hopper is arranged in the pre-sedimentation zone, the guide hopper is arranged at the bottom of the MBR membrane tank, and the backflow unit is used to backflow the sludge in the guide hopper to the AOA reaction tank.

[0018] Preferably, an aeration membrane assembly is arranged in the membrane filtration zone, the output unit comprises a water outlet pipe and a water outlet suction pump arranged on the water outlet pipe, and the water outlet pipe is connected with the aeration membrane assembly.

[0019] Preferably, a baffle is further arranged in the membrane filtration zone, the baffle is symmetrically arranged and located on both sides of the aeration membrane assembly, both ends of the baffle are connected to the inner wall of the MBR membrane tank, a sludge rising area is formed between the symmetrically arranged baffles, and a sludge sedimentation area is formed between the baffle and the MBR membrane tank.

[0020] Preferably, an inclined plate sedimentation module is further arranged in the MBR membrane tank, the inclined plate sedimentation module is located between the membrane filtration zone and the pre-sedimentation zone, and the outlet end of the AOA reaction tank is located below the inclined plate sedimentation module.

[0021] Compared with the prior art, the application has the following beneficial effects:

[0022] 1. The application sets the membrane filtration zone and the pre-sedimentation zone in the MBR membrane tank, so that most of the sludge in the mud-water mixture entering the MBR membrane tank is preliminarily separated in the pre-sedimentation zone and is concentrated by sedimentation at the bottom of the pre-sedimentation zone, the backflow concentration is improved, the backflow amount and the backflow energy consumption are reduced by backflowing to the AOA reaction tank through the backflow unit.

[0023] 2. The application makes full use of the fact that most of the nitrate in the mud-water mixture has been converted into nitrogen in the anoxic environment of the AOA reaction tank, the nitrate is relatively low, and the sludge after preliminary separation does not pass through the membrane filtration zone and does not pass through the oxygenation process by air blowing, so the dissolved oxygen and the nitrate are also relatively low, which is very beneficial to maintaining and guaranteeing the anoxic environment and the anaerobic environment in the AOA reaction tank after backflowing to the anoxic / anaerobic zone, and ensures the effect of denitrification and phosphorus removal. BRIEF DESCRIPTION OF DRAWINGS

[0024] Fig. 1is a structural schematic diagram of a sewage treatment system of embodiment 1 of the present application;

[0025] Fig. 2 is a piping diagram of a sewage treatment system of embodiment 1 of the present application;

[0026] Wherein, each reference numeral is as follows:

[0027] AOA reaction tank 1; MBR membrane tank 2; reflux unit 3; output unit 4; anaerobic zone 11; first switching zone 12; aerobic zone 13; second switching zone 14; anoxic zone 15; membrane filtration zone 21; pre-sedimentation zone 22; inclined plate sedimentation module 23; first control pipeline 31; second control pipeline 32; third control pipeline 33; effluent pipe 41; effluent suction pump 42; first stirring device 111; second stirring device 121; first aeration device 122; second aeration device 131; third stirring device 141; third aeration device 142; fourth stirring device 151; aeration membrane assembly 211; baffle 212; sludge rising area 213; sludge settling area 214; guide hopper 221; first reflux pipe 311; first reflux pump 312; first reflux valve 313; second reflux pipe 321; second reflux pump 322; second reflux valve 323; third reflux pipe 331; third reflux valve 332. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0029] Embodiment 1

[0030] Reference Figs. 1-2 An AOA-MBR sewage treatment system, comprising an AOA reaction tank 1, an MBR membrane tank 2 in communication with the AOA reaction tank 1, a reflux unit 3, and an output unit 4, the reflux unit 3 being configured to reflux sludge in the MBR membrane tank 2 to the AOA reaction tank 1, the MBR membrane tank 2 being provided with a membrane filtration zone 21 and a pre-sedimentation zone 22 in communication with each other, and an outlet end of the AOA reaction tank 1 being located between the membrane filtration zone 21 and the pre-sedimentation zone 22;

[0031] The pre-sedimentation zone 22 is configured to preliminarily separate the sludge-water mixture entering the MBR membrane tank 2, so as to make part of the sludge in the sludge-water mixture to be precipitated and concentrated, thereby increasing the concentration of the reflux sludge and reducing the reflux amount and reflux energy consumption through the reflux unit 3 to the AOA reaction tank 1;

[0032] The membrane filtration area 21 is used for re-separating the mud-water mixture after preliminary separation, and the separated water is discharged through the output unit 4.

[0033] In the embodiment, the AOA reaction tank 1 comprises an anaerobic area 11, a first switching area 12, an aerobic area 13, a second switching area 14 and an anoxic area 15 connected in sequence; the first stirring device 111 is arranged in the anaerobic area 11; the second stirring device 121 and the first aeration device 122 for switching between anaerobic and aerobic are arranged in the first switching area 12; the second aeration device 131 is arranged in the aerobic area 13; the third stirring device 141 and the third aeration device 142 for switching between aerobic and anoxic are arranged in the second switching area 14; the fourth stirring device 151 is arranged in the anoxic area 15; and the reflux unit 3 is used for refluxing the sludge in the MBR membrane tank 2 to the anaerobic area 11 and the second switching area 14 or the anoxic area 15.

[0034] The principle and working mode of the AOA reaction tank 1 can refer to the technical solution disclosed in Chinese patent CN112875859A.

[0035] Under this design, because the MBR membrane tank 2 is communicated with the anoxic area 15, most of the sludge in the pre-deposition area 22 comes from the sludge deposited from the anoxic area 15, rather than the sludge deposited from the membrane filtration area 21, and the dissolved oxygen in the mud-water mixture is relatively low; and the anoxic area 15 has converted most of the nitrate into nitrogen, so the dissolved oxygen and nitrate in the mud-water mixture are also relatively low, and the reflux to the anoxic area 15 and the anaerobic area 11 is very beneficial to maintaining and guaranteeing the anoxic environment and the anaerobic environment, and helps to improve the effect of denitrification and phosphorus removal.

[0036] In the embodiment, the membrane filtration area 21 is provided with an aeration membrane assembly 211, the output unit 4 comprises a water outlet pipe 41 and a water outlet suction pump 42 arranged on the water outlet pipe 41, and the water outlet pipe 41 is connected with the aeration membrane assembly 211.

[0037] Specifically, the aeration membrane assembly 211 is an MBR membrane assembly with an aeration pipe arranged therein, and the specific structure can refer to the MBR membrane assembly and the aeration main pipe disclosed in Chinese patent CN215627055U, so the specific structure and working principle of the aeration membrane assembly 211 are not described in detail in the embodiment. The aeration membrane assembly 211 in the embodiment can adopt the mode of ultrafiltration membrane plus aeration main pipe.

[0038] In actual use, after the sludge-water mixture is preliminarily separated, the sludge concentration in the membrane filtration zone 21 is low, the speed of membrane pollution is reduced, and the resistance of clean water through the membrane is greatly reduced. Therefore, a smaller membrane area can be used to achieve a larger water flux, the investment cost is reduced, the pumping energy consumption of the effluent is greatly reduced, the operation cost of the effluent is saved, and the frequency of membrane cleaning is reduced, and the operation cost of membrane cleaning is greatly reduced.

[0039] Further, the reflux unit 3 comprises a first control pipeline 31 for controlling the reflux of sludge in the MBR membrane tank 2 to the anaerobic zone 11, a second control pipeline 32 for controlling the reflux of sludge in the MBR membrane tank 2 to the anoxic zone 15, and a third control pipeline 33 for controlling the reflux of sludge in the MBR membrane tank 2 to the second switching zone 14.

[0040] In use, the second control pipeline 32 and the third control pipeline 33 need to be controlled according to the mode switching of the second switching zone 14. Specifically, when the third stirring device 141 in the second switching zone 14 is opened and the third aeration device 142 is closed, the second switching zone 14 is in anoxic state, the third control pipeline 33 is turned on, the second control pipeline 32 is closed, or both the third control pipeline 33 and the second control pipeline 32 are turned on; when the third stirring device 141 in the second switching zone 14 is closed and the third aeration device 142 is opened, the second switching zone 14 is in aerobic state, the third control pipeline 33 is closed, and the second control pipeline 32 is turned on.

[0041] In this embodiment, the third control pipeline 33 is connected at the feed inlet of the second switching zone 14. In this way, the sewage entering the second switching zone 14 in anoxic state can be mixed with the reflux sludge, further enhancing the denitrification effect.

[0042] Preferably, the first control pipeline 31 comprises a first reflux pipe 311, a first reflux pump 312 and a first reflux valve 313 arranged on the first reflux pipe 311; the second control pipeline 32 comprises a second reflux pipe 321, a second reflux pump 322 and a second reflux valve 323 arranged on the second reflux pipe 321; and the third control pipeline 33 comprises a third reflux pipe 331 and a third reflux valve 332 arranged on the third reflux pipe 331, and the third reflux pipe 331 is in communication with the second reflux pipe 321.

[0043] The second reflux valve 323, the third reflux valve 332, the third aeration device 142 and the third stirring device 141 are linked.

[0044] Specifically, when the third stirring device 141 is opened and the third aeration device 142 is closed, the second switching zone 14 is in anoxic state, the third reflux valve 332 is opened, the second reflux valve 323 is closed, or both the third reflux valve 332 and the second reflux valve 323 are opened.

[0045] When the third stirring device 141 is closed and the third aeration device 142 is opened, the second switching zone 14 is in an aerobic state, the third reflux valve 332 is closed and the second reflux valve 323 is opened. In this way, the position of reflux can be automatically switched when the second switching zone 14 is in a switching state.

[0046] In the present embodiment, the first reflux pipe 311 and the second reflux pipe 321 can also be communicated through a pipe, and implicitly, a valve is further arranged in the passage of the first reflux pipe 311 to the first reflux pump 312 and in the passage of the second reflux pipe 321 to the second reflux pump 322.

[0047] Preferably, a guide hopper 221 is arranged in the pre-sedimentation zone 22, the guide hopper 221 is arranged at the bottom of the MBR membrane tank 2, and the reflux unit 3 is used to reflux the sludge in the guide hopper 221 to the AOA reaction tank 1.

[0048] Under the guidance of the guide hopper 221, the preliminarily separated sludge is more concentrated and gathered at the bottom of the MBR membrane tank 2, and the concentration of the sludge reflux is improved. The number of the guide hoppers 221 can be arranged according to the area of the MBR membrane tank 2, and the number of the guide hoppers 221 is not limited in the present embodiment.

[0049] As a preferred embodiment in the present embodiment, a baffle 212 is further arranged in the membrane filtration zone 21, the baffle 212 is symmetrically arranged and located at both sides of the aeration membrane assembly 211, both ends of the baffle 212 are connected to the inner wall of the MBR membrane tank 2, a sludge rising area 213 is formed between the symmetrically arranged baffles 212, and a sludge settling area 214 is formed between the baffle 212 and the MBR membrane tank 2.

[0050] By arranging the baffle 212 at both sides of the aeration membrane assembly 211, in actual use, the aeration of the aeration membrane assembly 211 will form an upward airflow between the baffles 212, which promotes the sludge to pass through the baffle 212 and enter the sludge settling area 214, and the sludge sinks in the sludge settling area 214, thereby forming a circulation around the baffle 212, which strengthens the hydraulic flow state, so that the sludge has an accelerated settling effect outside the baffle 212, and most of the sludge can be removed by settling in the pre-sedimentation zone 22. The sludge is enriched and concentrated in the pre-sedimentation zone 22, and the amount of reflux sludge is greatly reduced, which can greatly reduce the energy consumption of the reflux sludge. After using the pre-sedimentation zone 22, the reflux ratio can be reduced to 100% to 200% compared with the conventional 400% to 800%, which greatly reduces the energy consumption of the sludge reflux.

[0051] Further, the MBR membrane tank 2 is further provided with an inclined plate sedimentation module 23, which is located between the membrane filtration area 21 and the pre-sedimentation area 22, and the outlet end of the AOA reaction tank 1 is located below the inclined plate sedimentation module 23. Specifically, the inclined plate sedimentation module 23 can adopt the structure of inclined plate or inclined pipe to improve the sedimentation effect, and also can avoid the return of sludge in the pre-sedimentation area 22 to the membrane filtration area 21, and the operator can also set an air or water backwashing unit at the bottom of the inclined plate sedimentation module 23 according to the actual situation to prevent blockage. The inclined plate sedimentation module 23 in the embodiment can refer to the inclined plate structure disclosed in Chinese patent CN108939621A.

[0052] Although the embodiments of the present application have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and purposes of the present application, and the scope of the present application is defined by the claims and their equivalents.

Claims

1. An AOA-MBR wastewater treatment system comprising an AOA reaction tank, an MBR membrane tank in communication with the AOA reaction tank, a backflow unit for backflowing sludge in the MBR membrane tank into the AOA reaction tank, and an output unit, characterized in that, The MBR membrane tank is internally provided with a membrane filtration zone and a pre-sedimentation zone in communication with each other, and the outlet end of the AOA reaction tank is located between the membrane filtration zone and the pre-sedimentation zone. The pre-sedimentation zone is used for preliminarily separating the sludge-water mixture entering the MBR membrane tank, so that part of the sludge in the sludge-water mixture is precipitated and concentrated, and then is returned to the AOA reaction tank through the return unit. The membrane filtration zone is used for re-separating the sludge-water mixture after the preliminary separation, and then discharging the separated water outside through the output unit.

2. The AOA-MBR wastewater treatment system according to claim 1, characterized in that, The AOA reaction tank comprises an anaerobic zone, a first switching zone, an aerobic zone, a second switching zone and an anoxic zone in sequence. The first stirring device is arranged in the anaerobic zone; the second stirring device and the first aeration device for switching between anaerobic and aerobic are arranged in the first switching zone; the second aeration device is arranged in the aerobic zone; the third stirring device and the third aeration device for switching between aerobic and anoxic are arranged in the second switching zone; the fourth stirring device is arranged in the anoxic zone; and the return unit is used for returning the sludge in the MBR membrane tank to the anaerobic zone and the second switching zone or the anoxic zone.

3. The AOA-MBR wastewater treatment system of claim 2, wherein, The return unit comprises a first control pipeline for controlling the return of the sludge in the MBR membrane tank to the anaerobic zone, a second control pipeline for controlling the return of the sludge in the MBR membrane tank to the anoxic zone, and a third control pipeline for controlling the return of the sludge in the MBR membrane tank to the second switching zone.

4. The AOA-MBR wastewater treatment system of claim 3, wherein, The third control pipeline is connected at the feed inlet of the second switching zone.

5. The AOA-MBR wastewater treatment system of claim 3, wherein, The first control pipeline comprises a first return pipeline, a first return pump arranged on the first return pipeline and a first return valve; the second control pipeline comprises a second return pipeline, a second return pump arranged on the second return pipeline and a second return valve; and the third control pipeline comprises a third return pipeline and a third return valve arranged on the third return pipeline, and the third return pipeline is in communication with the second return pipeline. The second return valve and the third return valve are linked with the third aeration device and the third stirring device.

6. The AOA-MBR wastewater treatment system of claim 1, wherein, The pre-sedimentation zone is internally provided with a guide hopper, the guide hopper is arranged at the bottom of the MBR membrane tank, and the return unit is used for returning the sludge in the guide hopper to the AOA reaction tank.

7. The AOA-MBR wastewater treatment system of claim 1, wherein, The membrane filtration zone is internally provided with an aeration membrane assembly, and the output unit comprises a water outlet pipeline and a water outlet suction pump arranged on the water outlet pipeline, and the water outlet pipeline is connected with the aeration membrane assembly.

8. The AOA-MBR wastewater treatment system of claim 7, wherein, The membrane filtration zone is further provided with a baffle, the baffle is symmetrically arranged and located on both sides of the aeration membrane assembly, both ends of the baffle are connected to the inner wall of the MBR membrane tank, a sludge rising area is formed between the symmetrically arranged baffles, and a sludge sedimentation area is formed between the baffle and the MBR membrane tank.

9. The AOA-MBR wastewater treatment system of claim 1, wherein, The MBR membrane tank is further internally provided with an inclined plate sedimentation module, the inclined plate sedimentation module is located between the membrane filtration zone and the pre-sedimentation zone, and the outlet end of the AOA reaction tank is located below the inclined plate sedimentation module.

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