Oxygen-eliminating and low-energy-consumption sewage treatment system

Abstract

The invention belongs to the technical field of sewage treatment, and particularly relates to an oxygen-eliminating low-energy-consumption sewage treatment system which comprises an AOA reaction tank, an MBR membrane tank, a separation unit, an oxygen-eliminating unit, a first reflux unit and a second reflux unit, sludge precipitates separated by the separation unit are conveyed into the oxygen elimination unit, and supernatant liquid is conveyed into an aerobic zone of the AOA reaction tank through a first reflux unit; the second reflux unit is used for conveying the sludge in the oxygen elimination unit into the anaerobic zone and / or the anoxic zone of the AOA reaction tank. Dissolved oxygen in the separation unit is fully utilized, meanwhile, the sludge backflow concentration is improved, and under the condition that the sludge concentration of the AOA reaction tank is ensured, the backflow amount of backflow liquid is reduced as much as possible; according to the present invention, the reflux energy consumption can be reduced, and the oxygen in the reflux sludge is completely eliminated after the reflux sludge is subjected to the oxygen elimination treatment, such that the maintenance and the guarantee of the anoxic environment, the anaerobic environment and the aerobic environment in the AOA reaction tank are easily achieved, the denitrification and phosphorus removal effects are improved, and the energy consumption is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to an oxygen-eliminating and low-energy-consumption sewage treatment system. Background Art

[0002] AOA process is the abbreviation of anaerobic (A) - aerobic (O) - anoxic (A) process. It omits internal reflow and adopts sludge double reflow mode. It converts the COD of the influent into the internal carbon source of the cell in the anaerobic section and seals these internal carbon sources in the body of the microorganism. After passing the aerobic zone, these internal carbon sources are used for denitrification in the anoxic zone, which can simultaneously remove nitrogen and phosphorus and reduce the consumption of external carbon sources.

[0003] MBR process, namely membrane bioreactor, is a sewage treatment technology that combines membrane separation technology with biological treatment. It combines membrane elements with bioreactors to achieve organic matter degradation and solid-liquid separation in the same device.

[0004] CN116477776A discloses a pre-phosphorus removal and post-endogenous denitrification coupled MBR sewage treatment system and process. The system mainly comprises a pre-phosphorus removal unit, a post-endogenous denitrification unit and a sludge return unit. The effluent from the grit chamber enters a flocculation sedimentation phosphorus removal tank for phosphorus removal; then the supernatant enters the post-endogenous denitrification unit, and the denitrifying bacteria in the anaerobic tank absorb the carbon source. In the dynamic aerobic tank, dynamic and precise nitrification is carried out in conjunction with detection instruments and control equipment, and then post-endogenous denitrification is carried out in the anoxic tank, thereby achieving deep denitrification; the effluent from the anoxic tank and the sludge enter the MBR membrane tank and the sludge return unit, and a double return system is adopted to maximize the function of the anaerobic zone, or a pre-anaerobic zone is set up to divert the influent and reduce the impact of high dissolved oxygen in the MBR membrane tank on the denitrifying bacteria.

[0005] The above technical solution solves the problems of low efficiency of traditional pre-denitrification denitrification, the contradiction between sludge age of post-biological phosphorus removal and denitrification, high suspended solids in biochemical effluent, and inability to selectively increase sludge concentration in winter. However, the above technical solution does not fully utilize the energy in the sludge thickening tank. Due to the high dissolved oxygen in the MBR membrane tank, this part of dissolved oxygen can provide oxygen for the previous process well, and the sludge in the sludge thickening tank can also enhance the denitrification effect of the previous process after re-treatment. Summary of the invention

[0006] The purpose of the present application is to solve the above-mentioned problems and to provide a sewage treatment system with oxygen elimination and low energy consumption. The sewage treatment system makes full use of the dissolved oxygen in the upper layer of liquid in the separation unit to supply oxygen to the aerobic zone, and at the same time can increase the concentration of sludge return and improve the denitrification effect. While ensuring the sludge concentration in the AOA reaction tank, the reflux amount of reflux liquid is minimized as much as possible; not only can the reflux energy consumption be reduced, but also the oxygen in the return sludge is fully eliminated after the return sludge is treated with oxygen elimination, which is very beneficial for maintaining and ensuring the anoxic environment, anaerobic environment, and aerobic environment in the AOA reaction tank, ensuring the effect of denitrification and phosphorus removal and reducing energy consumption.

[0007] To achieve the above objectives, this application provides the following technical solutions:

[0008] A wastewater treatment system with oxygen removal and low energy consumption, comprising an AOA reaction tank, an MBR membrane tank, a separation unit, an oxygen removal unit, a first reflux unit, and a second reflux unit;

[0009] The AOA reaction tank, the MBR membrane tank, the separation unit, and the deoxidation unit are connected in sequence;

[0010] The separation unit is used to re-separate the mud-water mixture output from the MBR membrane pool;

[0011] The sludge precipitate separated by the separation unit is transported to the oxygen elimination unit, and the upper layer of liquid rich in dissolved oxygen is transported to the aerobic zone of the AOA reaction tank through the first reflux unit;

[0012] The second reflow unit is used to transport the sludge from which dissolved oxygen is eliminated in the oxygen elimination unit to the anaerobic zone and / or the anoxic zone of the AOA reaction tank.

[0013] Preferably, the separation unit includes a separation tank, an inclined plate assembly connected to the separation tank, and a guide funnel, the guide funnel is located at the bottom of the separation tank, the inclined plate assembly is located above the guide funnel, the input end of the separation tank is located between the inclined plate assembly and the guide funnel, and the output end of the separation tank is located above the inclined plate assembly.

[0014] Preferably, the deoxidation unit comprises a deoxidation tank and a stirring mechanism connected to the deoxidation tank. The deoxidation tank is provided with an input pipe connected to an external deoxidizer delivery device. The input end of the deoxidation tank is located below the stirring mechanism. The second reflux unit is connected to the deoxidation tank.

[0015] Preferably, the second reflux unit includes a first reflux module and a second reflux module, the first reflux module is used to transport the sludge after the dissolved oxygen in the oxygen removal unit to the anaerobic zone of the AOA reaction tank; the second reflux module is used to transport the sludge after the dissolved oxygen in the oxygen removal unit to the anoxic zone of the AOA reaction tank.

[0016] Preferably, the AOA reaction tank comprises an anaerobic zone, a first switching zone, an aerobic zone, a second switching zone and an anoxic zone which are connected in sequence;

[0017] 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;

[0018] The first reflux unit is used to reflux the upper layer of liquid rich in dissolved oxygen in the separation unit to the first switching zone and / or the aerobic zone in an aerobic state;

[0019] The first reflow module is used to return the sludge after the dissolved oxygen is eliminated in the oxygen elimination unit to the anaerobic zone; the second reflow module is used to return the sludge after the dissolved oxygen is eliminated in the oxygen elimination unit to the second switching zone and / or the anoxic zone in the anoxic state.

[0020] Preferably, the MBR membrane tank comprises a tank body, an aeration membrane assembly arranged in the tank body, an outlet pipe connected to the aeration membrane assembly, and an outlet pump arranged on the outlet pipe, and the output end of the tank body is located at the bottom.

[0021] Preferably, it also includes baffles, which are symmetrically arranged and set in the tank body. The aeration membrane assembly is located between the symmetrically arranged baffles, and a sludge rising area is formed between the symmetrically arranged baffles. A gap is provided between the baffle and the inner wall of the tank body, and the gap is a sludge settling area.

[0022] Preferably, the first reflux unit comprises a first reflux pipe, a first reflux pump and a first reflux valve arranged on the first reflux pipe, and the first reflux pipe is used to reflux the upper layer of liquid rich in dissolved oxygen in the separation unit to the first switching zone and / or aerobic zone in an aerobic state.

[0023] Preferably, the first reflux module includes a second reflux pipe, a second reflux pump and a second reflux valve arranged on the second reflux pipe, and the second reflux pipe is used to return the sludge after the dissolved oxygen is eliminated in the oxygen removal unit to the anaerobic zone; the second reflux module includes a third reflux pipe, a third reflux pump and a third reflux valve arranged on the third reflux pipe, and the third reflux pipe is used to return the sludge after the dissolved oxygen is eliminated in the oxygen removal unit to the second switching zone and / or the anoxic zone in the anoxic state.

[0024] Compared with the prior art, the beneficial effects of this application are:

[0025] The present application adds a separation unit and a deoxygenation unit, and separates the mud-water mixture into sludge sediment and upper liquid through the separation unit, and transports the sludge sediment to the deoxygenation unit for deoxygenation treatment, while the upper liquid rich in dissolved oxygen is transported to the aerobic zone of the AOA reaction tank via the first reflux unit, thereby fully utilizing the dissolved oxygen in the upper liquid, and supplying oxygen to the aerobic zone, thereby fully utilizing the oxygen in the upper liquid, and reducing oxygen consumption and energy consumption; at the same time, the sludge after deoxygenation in the deoxygenation unit fully eliminates the oxygen in the returned sludge, and will be transported to the anaerobic zone and / or anoxic zone of the AOA reaction tank, which is very beneficial for maintaining and ensuring the anoxic environment, anaerobic environment, and aerobic environment in the AOA reaction tank, thereby improving the denitrification and phosphorus removal effects, and reducing energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a pipeline diagram of the oxygen-eliminating and low-energy-consumption sewage treatment system of Example 1;

[0027] Figure 2 Schematic diagram of the structure of the AOA reaction tank and the MBR membrane tank of Example 1;

[0028] The reference numerals of the accompanying drawings are as follows:

[0029] AOA reaction tank 1; MBR membrane tank 2; separation unit 3; deoxidation unit 4; first reflux unit 5; second reflux unit 6; anaerobic zone 11; first switching zone 12; aerobic zone 13; second switching zone 14; anoxic zone 15; tank body 21; aeration membrane assembly 22; outlet pipe 23; outlet pump 24; baffle 25; separation tank 31; inclined plate assembly 32; guide funnel 33; deoxidation tank 41; stirring mechanism 42; input pipe 43; first reflux pipe 51; first reflux pump 52 ; first reflux valve 53; first reflux module 61; second reflux module 62; first stirring device 111; second stirring device 121; first aeration device 122; third stirring device 131; second aeration device 132; fourth stirring device 141; third aeration device 142; fifth stirring device 151; second reflux pipe 611; second reflux pump 612; second reflux valve 613; third reflux pipe 621; third reflux pump 622; third reflux valve 623. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] Example 1

[0032] refer to Figures 1-2 , a wastewater treatment system with oxygen elimination and low energy consumption, comprising an AOA reaction tank 1, an MBR membrane tank 2, a separation unit 3, an oxygen elimination unit 4, a first reflux unit 5, and a second reflux unit 6;

[0033] AOA reaction tank 1, MBR membrane tank 2, separation unit 3, and deoxidation unit 4 are connected in sequence;

[0034] The separation unit 3 is used to separate the mud-water mixture output from the MBR membrane pool 2 again;

[0035] The sludge precipitate separated by the separation unit 3 is transported to the oxygen elimination unit 4, and the upper layer of liquid rich in dissolved oxygen is transported to the aerobic zone 13 of the AOA reaction tank 1 through the first reflux unit 5;

[0036] The second reflow unit 6 is used to transport the sludge from which dissolved oxygen has been eliminated in the oxygen elimination unit 4 to the anaerobic zone 11 and / or the anoxic zone 15 of the AOA reaction tank 1 .

[0037] Under this design, because the anoxic zone 15 is connected to the MBR membrane tank 2, the dissolved oxygen of the sludge in the mud-water mixture entering the MBR membrane tank 2 will be relatively low. However, under the continuous aeration of the MBR membrane tank 2, the dissolved oxygen in the mud-water mixture will gradually increase. The purpose of the separation unit 3 is to utilize the dissolved oxygen brought out from the MBR membrane tank 2. Specifically, the mud-water mixture is separated into sludge sediment and an upper layer of liquid rich in dissolved oxygen through the separation unit 3, and the upper layer of liquid rich in dissolved oxygen is transported to the aerobic zone 13 of the AOA reaction tank 1 through the first reflux unit 5 to supply oxygen to the aerobic zone 13 and reduce energy consumption. After the sludge is precipitated and precipitated, the sludge concentration is increased, and after being transported to the deoxygenation unit 4 for deoxygenation, it is transported to the anaerobic zone 11 and / or the anoxic zone 15 of the AOA reaction tank 1 through the second reflux unit 6, further enhancing the denitrification effect and saving the sludge transportation volume and transportation energy consumption.

[0038] In this embodiment, the separation unit 3 includes a separation tank 31, an inclined plate assembly 32 connected to the separation tank 31, and a guide funnel 33, the guide funnel 33 is located at the bottom of the separation tank 31, the inclined plate assembly 32 is located above the guide funnel 33, the input end of the separation tank 31 is located between the inclined plate assembly 32 and the guide funnel 33, and the output end of the separation tank 31 is located above the inclined plate assembly 32.

[0039] Specifically, under the guidance of the guide funnel 33, the sludge entering the separation tank 31 is more concentrated at the bottom of the separation tank 31, thereby increasing the concentration of the sludge transported to the deoxidation unit 4. The inclined plate assembly 32 can adopt an inclined plate or inclined tube structure to improve the sedimentation effect, and can also prevent the sludge in the guide funnel 33 from flowing back to the upper liquid.

[0040] In addition, the separation tank 31 may also use mechanical concentrating devices such as spiral concentrators and concentrators to quickly separate the muddy and water mixture entering the separation tank 31. In actual use, the residence time of the muddy and water mixture in the separation tank 31 is controlled to be 0.5h to 1h to ensure that the dissolved oxygen in the upper liquid is not quickly consumed. Among them, the inclined plate assembly 32 in this embodiment can refer to the inclined plate structure disclosed in Chinese patent CN108939621A.

[0041] Furthermore, the deoxidation unit 4 includes a deoxidation tank 41 and a stirring mechanism 42 connected to the deoxidation tank 41. The deoxidation tank 41 is provided with an input pipe 43 connected to an external deoxidizer conveying device. The input end of the deoxidation tank 41 is located below the stirring mechanism 42. The second reflux unit 6 is connected to the deoxidation tank 41.

[0042] Specifically, the main purpose of the deoxygenation tank 41 is to further eliminate dissolved oxygen in the sludge. In actual use, the residence time of the sludge in the deoxygenation tank 41 should be more than 0.5 hours. To further improve the deoxygenation effect, deoxygenating agents such as sodium sulfite can be added through the input pipe 43; the stirring mechanism 42 can ensure good mixing of the sludge tank, and finally the deoxygenated sludge is transported to the anaerobic zone 11 and / or the anoxic zone 15 of the AOA reaction tank 1 through the second reflux unit 6.

[0043] Moreover, the sludge separated by the separation tank 31 has a higher concentration, and the deoxidation in the deoxidation tank 41 is more concentrated and targeted, and the amount returned to the anaerobic and anoxic units will be reduced, and the corresponding energy consumption can also be saved.

[0044] In this embodiment, the second reflux unit 6 includes a first reflux module 61 and a second reflux module 62. The first reflux module 61 is used to transport the sludge after the dissolved oxygen is eliminated in the deoxygenation unit 4 to the anaerobic zone 11 of the AOA reaction tank 1; the second reflux module 62 is used to transport the sludge after the dissolved oxygen is eliminated in the deoxygenation unit 4 to the anoxic zone 15 of the AOA reaction tank 1.

[0045] In actual application, the first reflux module 61 and the second reflux module 62 are independently metered and controlled without interfering with each other. The sludge after deoxygenation is returned to the anaerobic zone 11 through the first reflux module 61, so that the sewage newly entering the anaerobic zone 11 can contact with the sludge after the dissolved oxygen is eliminated. The sludge after deoxygenation is returned to the anoxic zone 15 through the second reflux module 62, so that the mud-water mixture coming out of the aerobic zone 13 can contact with the sludge after the dissolved oxygen is eliminated. This is very beneficial for maintaining and ensuring the anoxic environment and the anaerobic environment, and helps to improve the effect of denitrification and phosphorus removal.

[0046] In this embodiment, the AOA reaction tank 1 includes an anaerobic zone 11, a first switching zone 12, an aerobic zone 13, a second switching zone 14 and an anoxic zone 15 which are connected in sequence;

[0047] The anaerobic zone 11 is provided with a first stirring device 111; the first switching zone 12 is provided with a second stirring device 121 and a first aeration device 122 for switching between anaerobic and aerobic conditions; the aerobic zone 13 is provided with a second aeration device 132 and a third stirring device 131; the second switching zone 14 is provided with a fourth stirring device 141 and a third aeration device 142 for switching between aerobic and anoxic conditions; the anoxic zone 15 is provided with a fifth stirring device 151;

[0048] The first reflux unit 5 is used to reflux the upper layer of liquid rich in dissolved oxygen in the separation unit 3 to the first switching zone 12 and / or the aerobic zone 13 in an aerobic state;

[0049] The first reflow module 61 is used to return the sludge after the dissolved oxygen is eliminated in the oxygen removal unit 4 to the anaerobic zone 11; the second reflow module 62 is used to return the sludge after the dissolved oxygen is eliminated in the oxygen removal unit 4 to the second switching zone 14 and / or the anoxic zone 15 in the anoxic state.

[0050] For the principle and working mode of the AOA reaction tank 1, reference may be made to the technical solution disclosed in Chinese patent CN112875859A.

[0051] In short, in the first switching zone 12, when the first aeration device 122 is closed and the second stirring device 121 is turned on, the first switching zone 12 is in an anaerobic state. At this time, the first reflux unit 5 returns the upper layer of liquid rich in dissolved oxygen to the aerobic zone 13, but not to the first switching zone 12; when the upper layer of liquid rich in dissolved oxygen returns to the first switching zone 12, the first switching zone 12 is in an aerobic state. At this time, because of the dissolved oxygen supplement of the upper layer of liquid, the aeration amount of the first aeration device 122 is very small or does not work, so it is difficult to push the sludge, so the second stirring device 121 is also required to cooperate for pushing the flow, so the first aeration device 122 and the second stirring device 121 are turned on according to the mixing state of the sludge in the first switching zone 12.

[0052] Furthermore, the aerobic zone 13 is provided with not only a second aeration device 132 but also a third stirring device 131. Due to the reflux of the upper layer of liquid rich in dissolved oxygen, in this embodiment, the aeration volume of the second aeration device 132 is relatively small. When the dissolved oxygen in the aerobic zone 13 can meet the oxygen supply requirements of the system and can maintain the suspension of the mud-water mixture uniformly, the third stirring device 131 is closed; when the dissolved oxygen in the aerobic zone 13 can meet the oxygen supply requirements of the system but is insufficient to maintain the suspension of the mud-water mixture uniformly, the third stirring device 131 is turned on to ensure that the sludge in the aerobic zone 13 is evenly mixed. In other words, the third stirring device 131 in the aerobic zone 13 only plays the role of ensuring that the sludge in the aerobic zone 13 is evenly mixed. It is turned on according to the mixing state, but is not necessarily turned on all the time.

[0053] Furthermore, in the second switching zone 14, when the third aeration device 142 is turned on and the fourth stirring device 141 is turned off, the second switching zone 14 is in an aerobic state, and the second reflux module 62 returns the sludge after the dissolved oxygen is eliminated to the anoxic zone 15 instead of returning it to the second switching zone 14; when the third aeration device 142 is turned off and the fourth stirring device 141 is turned on, the second reflux module 62 returns the sludge after the dissolved oxygen is eliminated to the second switching zone 14, and the second switching zone 14 is in an anoxic state. Of course, the second reflux module 62 can also return the sludge after the dissolved oxygen is eliminated to the second switching zone 14 and the anoxic zone 15.

[0054] In this embodiment, the MBR membrane pool 2 includes a pool body 21, an aeration membrane assembly 22 disposed in the pool body 21, an outlet pipe 23 connected to the aeration membrane assembly 22, and an outlet pump 24 disposed on the outlet pipe 23. The output end of the pool body 21 is located at the bottom.

[0055] Specifically, the aeration membrane assembly 22 is an MBR membrane assembly with a built-in aeration pipe. The specific structure can refer to the MBR membrane assembly and aeration main pipe disclosed in Chinese patent CN215627055U. Therefore, the specific structure and working principle of the aeration membrane assembly 22 are not described in detail in this embodiment. The aeration membrane assembly 22 of this embodiment can adopt the method of ultrafiltration membrane plus aeration main pipe.

[0056] Preferably, it also includes baffles 25, which are symmetrically arranged and set in the tank body 21. The aeration membrane assembly 22 is located between the symmetrically arranged baffles 25, and a sludge rising area is formed between the symmetrically arranged baffles 25. A gap is provided between the baffles 25 and the inner wall of the tank body 21, and the gap is a sludge settling area.

[0057] Under this design, part of the sludge in the mud-water mixture entering the tank body 21 will directly settle at the bottom of the tank body 21, while the other part will enter the sludge rising area driven by the airflow of the aeration membrane assembly 22. In the sludge rising area, the sludge is constantly disturbed by bubbles, so that it is suspended in the water, and driven by the airflow of the aeration membrane assembly 22, the sludge passes over the baffle 25 from the top of the baffle 25 and enters the sludge settling area. The sludge in the sludge settling area is not affected by the bubbles, so the sludge settling area can accelerate the sedimentation of the sludge, and at the bottom of the baffle 25, the airflow of the aeration membrane assembly 22 will cause a low-pressure area to form at the bottom of the baffle 25, prompting the water flow at the bottom of the sludge settling area and a small part of the sludge to enter the sludge rising area, thereby forming a circulation around the baffle 25, promoting the sedimentation of the sludge, and reducing the burden of the aeration membrane assembly 22.

[0058] In this embodiment, the first reflux unit 5 includes a first reflux pipe 51, a first reflux pump 52 and a first reflux valve 53 arranged on the first reflux pipe 51, and the first reflux pipe 51 is used to reflux the upper layer of liquid rich in dissolved oxygen in the separation unit 3 to the first switching zone 12 and / or the aerobic zone 13 in an aerobic state.

[0059] Specifically, when the first reflux pipe 51 flows back to the first switching zone 12, the first switching zone 12 is in an aerobic state, and the first aeration device 122 and the second stirring device 121 in the first switching zone 12 are turned on according to the mixing state of the sludge. When the first aeration device 122 is turned off and the second stirring device 121 is turned on, the first switching zone 12 is in an anaerobic state, and the first reflux pipe 51 flows the upper layer of liquid rich in dissolved oxygen back to the aerobic zone 13 instead of back to the first switching zone 12.

[0060] It should be noted that the first reflux pipe 51 further includes two first branch pipes, each of which is provided with a first reflux valve 53, and the two first branch pipes respectively control the reflux to the first switching zone 12 and the aerobic zone 13 through their respective first reflux valves 53. In a preferred embodiment, the output ends of the two first branch pipes are respectively connected to the input end of the first switching zone 12 and the input end of the aerobic zone 13.

[0061] Furthermore, the first reflux module 61 includes a second reflux pipe 611, a second reflux pump 612 and a second reflux valve 613 arranged on the second reflux pipe 611, and the second reflux pipe 611 is used to return the sludge after the dissolved oxygen is eliminated in the oxygen removal unit 4 to the anaerobic zone 11; the second reflux module 62 includes a third reflux pipe 621, a third reflux pump 622 and a third reflux valve 623 arranged on the third reflux pipe 621, and the third reflux pipe 621 is used to return the sludge after the dissolved oxygen is eliminated in the oxygen removal unit 4 to the second switching zone 14 and / or the anoxic zone 15 in the anoxic state.

[0062] Specifically, the second return pipe 611 is mainly used to return the sludge after the dissolved oxygen is eliminated to the water inlet of the anaerobic zone 11; when the second switching zone 14 is in an anoxic state, the third return pipe 621 returns the sludge after the dissolved oxygen is eliminated to the second switching zone 14, and when the second switching zone 14 is in an aerobic state, the third return pipe 621 returns the sludge after the dissolved oxygen is eliminated to the anoxic zone 15. Of course, the third return pipe 621 can also return the sludge after the dissolved oxygen is eliminated to the second switching zone 14 and the anoxic zone 15 in the anoxic state.

[0063] It should be noted that the third reflux pipe 621 further includes two second branch pipes, each of which is provided with a third reflux valve 623, and the two second branch pipes are respectively controlled to reflux to the second switching zone 14 and the anoxic zone 15 through their respective third reflux valves 623. In a preferred embodiment, the output ends of the two second branch pipes are respectively connected to the input end of the second switching zone 14 and the input end of the anoxic zone 15.

[0064] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A sewage treatment system with oxygen elimination and low energy consumption, characterized in that: It includes AOA reaction tank, MBR membrane tank, separation unit, deoxidation unit, first reflux unit and second reflux unit; The AOA reaction tank, the MBR membrane tank, the separation unit, and the deoxidation unit are connected in sequence; The separation unit is used to re-separate the mud-water mixture output from the MBR membrane pool; The sludge precipitate separated by the separation unit is transported to the oxygen elimination unit, and the upper layer of liquid rich in dissolved oxygen is transported to the aerobic zone of the AOA reaction tank through the first reflux unit; The second reflow unit is used to transport the sludge in the oxygen removal unit after the dissolved oxygen is eliminated to the anaerobic zone and / or the anoxic zone of the AOA reaction tank.

2. The oxygen-eliminating and low-energy-consumption sewage treatment system according to claim 1 is characterized in that: The separation unit includes a separation tank, an inclined plate assembly connected to the separation tank, and a guide funnel, wherein the guide funnel is located at the bottom of the separation tank, the inclined plate assembly is located above the guide funnel, the input end of the separation tank is located between the inclined plate assembly and the guide funnel, and the output end of the separation tank is located above the inclined plate assembly.

3. The oxygen-eliminating and low-energy-consumption sewage treatment system according to claim 1 is characterized in that: The deoxidation unit comprises a deoxidation tank and a stirring mechanism connected to the deoxidation tank. The deoxidation tank is provided with an input pipe connected to an external deoxidizer conveying device. The input end of the deoxidation tank is located below the stirring mechanism. The second reflux unit is connected to the deoxidation tank.

4. The oxygen-eliminating and low-energy-consumption sewage treatment system according to claim 1 is characterized in that: The second reflux unit includes a first reflux module and a second reflux module. The first reflux module is used to transport the sludge in the oxygen removal unit after oxygen is eliminated to the anaerobic zone of the AOA reaction tank; the second reflux module is used to transport the sludge in the oxygen removal unit after oxygen is eliminated to the anoxic zone of the AOA reaction tank.

5. The oxygen-eliminating and low-energy-consumption sewage treatment system according to claim 4 is 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 which are connected in sequence; 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 first reflux unit is used to reflux the upper layer of liquid rich in dissolved oxygen in the separation unit to the first switching zone and / or the aerobic zone in an aerobic state; The first reflow module is used to return the sludge after the dissolved oxygen is eliminated in the oxygen elimination unit to the anaerobic zone; The second reflow module is used to reflow the sludge in the oxygen removal unit after the dissolved oxygen is eliminated to the second switching zone and / or the anoxic zone in the anoxic state.

6. The oxygen-eliminating and low-energy-consumption sewage treatment system according to claim 1 is characterized in that: The MBR membrane pool comprises a pool body, an aeration membrane assembly arranged in the pool body, a water outlet pipe connected to the aeration membrane assembly, and a water outlet pump arranged on the water outlet pipe. The output end of the pool body is located at the bottom.

7. The oxygen-eliminating and low-energy-consumption sewage treatment system according to claim 6 is characterized in that: It also includes baffles, which are symmetrically arranged and set in the tank body. The aeration membrane assembly is located between the symmetrically arranged baffles, and a sludge rising area is formed between the symmetrically arranged baffles. A gap is set between the baffle and the inner wall of the tank body, and the gap is a sludge settling area.

8. The oxygen-eliminating and low-energy-consumption sewage treatment system according to claim 5 is characterized in that: The first reflux unit comprises a first reflux pipe and a first reflux pump arranged on the first reflux pipe, and the first reflux pipe is used to reflux the upper layer of liquid rich in dissolved oxygen in the separation unit to the first switching zone and / or the aerobic zone in an aerobic state.

9. The oxygen-eliminating and low-energy-consumption sewage treatment system according to claim 5, characterized in that: The first reflux module includes a second reflux pipe, a second reflux pump and a second reflux valve arranged on the second reflux pipe, and the second reflux pipe is used to return the sludge in the oxygen removal unit after the dissolved oxygen is eliminated to the anaerobic zone; the second reflux module includes a third reflux pipe, a third reflux pump and a third reflux valve arranged on the third reflux pipe, and the third reflux pipe is used to return the sludge in the oxygen removal unit after the dissolved oxygen is eliminated to the second switching zone and / or the anoxic zone in the anoxic state.

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