A sewage treatment device for enhanced denitrification and dephosphorization

Abstract

The present application relates to a kind of enhanced denitrification and phosphorus removal sewage treatment device, including the anaerobic pool, anoxic pool, first composite biochemical pool and second composite biochemical pool connected in sequence, first composite biochemical pool is equipped with several composite biological carrier components, and is equipped with first aeration pipe;Second composite biochemical pool is equipped with several MABR membrane components;Anaerobic pool is equipped with first exhaust pipe, and the gas outlet end of first exhaust pipe is equipped with several first branch pipe;Anoxic pool is equipped with second exhaust pipe, and the gas outlet end of second exhaust pipe is equipped with several second branch pipe, and first branch pipe and second branch pipe are connected first aeration pipe and several MABR membrane components respectively;Composite biological carrier component surface load aerobic microorganism, and the membrane filament surface of MABR membrane component is loaded aerobic microorganism, anoxic microorganism and anaerobic microorganism from inside to outside, realizes simultaneous nitrification and denitrification.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a wastewater treatment device for enhanced nitrogen and phosphorus removal. Background Technology

[0002] Wastewater treatment has always been a vital industrial sector serving both industrial production and daily life. Wastewater treatment technologies are currently relatively mature and can generally meet discharge requirements. However, with industrial development entering a new stage, enterprise transformation, and product upgrades have led to changes in the composition of wastewater, increasing the difficulty of degradation and treatment. Simultaneously, increasingly stringent and demanding effluent discharge standards pose new challenges to wastewater treatment. This is primarily manifested in the heavy load on biological treatment units, making it difficult for conventional processes to achieve compliant discharge levels during subsequent nitrogen and phosphorus removal. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a wastewater treatment device for enhanced nitrogen and phosphorus removal, comprising an anaerobic tank, an anoxic tank, a first composite biological tank, and a second composite biological tank connected in sequence. The first composite biological tank contains a plurality of composite biological carrier components and a first aeration pipe; the second composite biological tank contains a plurality of MABR membrane components.

[0004] The anaerobic tank is equipped with a first waste gas pipe, and the outlet of the first waste gas pipe is equipped with several first branch pipes, which are respectively connected to the first aeration pipe and several MABR membrane modules; the anoxic tank is equipped with a second waste gas pipe, and the outlet of the second waste gas pipe is equipped with several second branch pipes, which are respectively connected to the first aeration pipe and several MABR membrane modules; the external aeration device is connected in parallel with the first aeration pipe and several MABR membrane modules through the air path to provide oxygen to the first composite biological tank and the second composite biological tank, as well as the waste gas generated by the anaerobic tank and the anoxic tank;

[0005] The composite biological carrier component is loaded with aerobic microorganisms on its surface. The membrane fiber surface of the MABR membrane component is loaded with aerobic microorganisms, anoxic microorganisms and anaerobic microorganisms from the inside to the outside, so as to achieve simultaneous nitrification and denitrification.

[0006] Optionally, the first composite biological tank is a cuboid with water entering from the upper part of one side and water exiting from the lower part of the other side. Several first baffles are arranged along the length direction, so that the sewage flows through the length direction of the first composite biological tank in a tortuous manner. A composite biological carrier component is provided between two adjacent first baffles.

[0007] The bottom of the first composite biological tank is provided with a first aeration pipe. The first aeration pipe passes through each of the first baffles and is evenly distributed at the bottom of the first composite biological tank. The first aeration pipe is located below the composite biological carrier component. An external aeration device is connected to the first aeration pipe to provide oxygen to the first composite biological tank.

[0008] Optionally, the second composite biological treatment tank is a cuboid, and several second baffles are arranged along its length, so that the sewage flows up and down through the length of the second composite biological treatment tank in a tortuous manner, and a MABR membrane module is provided between two adjacent second baffles.

[0009] Optionally, the composite biological carrier assembly includes an upper support, several biological carriers and a lower support, with the top end of the biological carrier fixed on the upper support and the bottom end fixed on the lower support, and several biological carriers arranged in a matrix evenly in several rows and columns between the upper support and the lower support.

[0010] The biological carrier consists of at least two spirally intertwined willow twigs and several soft sponges between the twigs. The willow twigs are relatively thin and flexible, and the fibers are relatively fine.

[0011] Further optionally, the willow twigs have an average diameter of 1-5 mm, the soft sponges have a particle size of 3-8 mm, and several soft sponges are evenly distributed between two intertwined willow twigs, relying on the force of the intertwining to fix the soft sponges and prevent them from being washed away by the sewage flow.

[0012] Optionally, the biological carrier can be prepared as follows:

[0013] (1) Immerse the willow twigs entirely in the ethanol solution to ensure they are fully soaked;

[0014] (2) Immerse the willow twigs in an acidic solution until fully soaked, and then wash them with an ethanol solution until neutral.

[0015] (3) Immerse the willow twigs in an alkaline solution until fully soaked, then rinse with an ethanol solution until neutral.

[0016] (4) The willow twigs obtained in step (3) are spirally intertwined with each other, and several soft sponges are evenly placed in them to obtain the biological carrier.

[0017] Optionally, the MABR membrane module is placed vertically, parallel to the composite biological carrier module, with air intake at the bottom and a pressure gauge at the top; a dissolved oxygen meter is installed in the second composite biological tank to measure the dissolved oxygen concentration in the second composite biological tank; the MABR membrane module is a hollow fiber curtain membrane.

[0018] External aeration devices are connected to the bottom of each MABR membrane module to provide oxygen to the MABR membrane module.

[0019] The anaerobic tank contains anaerobic granular sludge. Wastewater typically contains some calcium ions, which, after long-term operation, will form precipitated calcium salts. These salts deposit on the surface of the granular sludge or enter the interior through the micropores of the granular sludge, forming scale and nuclei. This makes the surface or interior relatively solid, feeling like pebbles to the touch, indicating calcification of the anaerobic granular sludge. Calcification isolates microorganisms from contact with the substrate in the wastewater, hindering microbial growth and metabolism, leading to decreased sludge activity or even inactivation. Furthermore, the dissolved oxygen content in the first combined biological treatment tank is higher than that in the second combined biological treatment tank. If the effluent from the first combined biological treatment tank is directly fed into the second combined biological treatment tank, the high oxygen content will be detrimental to the biological treatment in the second combined biological treatment tank. To address these issues and ensure the long-term operation of the anaerobic tanks in the wastewater treatment device, and to circulate and treat the calcified anaerobic granular sludge, the following solution is provided.

[0020] Optionally, the enhanced nitrogen and phosphorus removal wastewater treatment device further includes a sludge regeneration unit, including a decalcification tank, a regeneration tank, and a deoxygenation tank. The top of the decalcification tank is provided with a sludge inlet and an acid addition inlet, and the bottom is provided with a decalcification inlet. The bottom of the anaerobic tank is provided with a sludge discharge inlet, which is connected to the sludge inlet through a pipe and a sludge pump. The acid addition inlet is used to add phosphoric acid decalcification agent.

[0021] Downstream of the first composite biological treatment tank, a deoxygenation tank and a regeneration tank are set up in sequence. Downstream of the regeneration tank is the second composite biological treatment tank. The decalcified granular sludge from the decalcification tank is fed into the regeneration tank. The wastewater treated by the first composite biological treatment tank is also fed into the regeneration tank after being deoxygenated in the deoxygenation tank.

[0022] Optionally, the decalcification tank is equipped with a second stirrer to promote the full reaction between the calcified granular sludge and the phosphoric acid solution to generate calcium phosphate. Under the stirring action, the calcium phosphate is separated from the granular sludge.

[0023] The upper part of the decalcification tank is equipped with a sewage outlet for real-time discharge of water containing calcium phosphate precipitate. After filtration and separation, the water can be returned to the decalcification tank, while the calcium phosphate is treated separately.

[0024] Optionally, the inlet of the deoxygenation tank is connected to the outlet of the first composite biological tank, and the outlet of the deoxygenation tank is connected to the inlet of the regeneration tank. Aquatic plants and phytoplankton are planted in the deoxygenation tank, and the top surface of the deoxygenation tank is equipped with an openable and closable top plate to provide an intermittent sealed environment for the deoxygenation tank. When sealed, it prevents sunlight from entering the deoxygenation tank and promotes the rapid consumption of dissolved oxygen in the water by the plants in the deoxygenation tank.

[0025] Optionally, the regeneration tank is provided with an inlet, a first sludge outlet, and a second sludge outlet on the side near the deoxygenation tank, and an outlet and a third sludge outlet on the side near the second composite biological treatment tank.

[0026] The outlet of the regeneration tank is connected to the inlet of the second composite biological treatment tank; the decalcification port of the decalcification tank is connected to the first sludge port, into which decalcified sludge is input; the second sludge port is connected to the anaerobic tank, used to input the activated sludge from the anaerobic tank into the regeneration tank; and the third sludge port is connected to the anaerobic tank, used to return the regenerated anaerobic granular sludge to the anaerobic tank. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the wastewater treatment device for enhanced nitrogen and phosphorus removal.

[0028] Figure 2 This is a schematic diagram of the first composite biological treatment tank;

[0029] Figure 3 This is a schematic diagram of the second composite biological treatment tank;

[0030] Figure 4 This is a schematic diagram of a biological carrier.

[0031] In the attached diagram, 1-anaerobic tank, 2-anoxic tank, 3-first composite biological tank, 4-second composite biological tank, 5-composite biological carrier component, 6-first aeration pipe, 7-MABR membrane component, 8-first waste gas pipe, 9-second waste gas pipe, 10-first baffle plate, 11-second baffle plate, 12-upper support, 13-lower support, 14-biological carrier, 15-soft sponge, 16-willow twig, 17-decalcification tank, 18-regeneration tank, 19-decalcification outlet, 20-sewage outlet, 21-first sludge outlet, 22-second sludge outlet, 23-third sludge outlet, 24-deoxygenation tank. Detailed Implementation

[0032] This embodiment provides a wastewater treatment device for enhanced nitrogen and phosphorus removal, such as... Figures 1-4 As shown, it includes an anaerobic tank 1, an anoxic tank 2, a first composite biochemical tank 3, and a second composite biochemical tank 4 connected in sequence. The first composite biochemical tank 3 is equipped with several composite biological carrier 14 components 5 and a first aeration pipe 6. The second composite biochemical tank 4 is equipped with several MABR membrane components 7.

[0033] Anaerobic tank 1 is equipped with a first waste gas pipe 8, and the outlet end of the first waste gas pipe 8 is equipped with several first branch pipes, which are respectively connected to the first aeration pipe 6 and several MABR membrane modules 7; anoxic tank 2 is equipped with a second waste gas pipe 9, and the outlet end of the second waste gas pipe 9 is equipped with several second branch pipes, which are respectively connected to the first aeration pipe 6 and several MABR membrane modules 7; an external aeration device is connected in parallel with the first aeration pipe 6 and several MABR membrane modules 7 through an air path to provide oxygen to the first composite biological tank 3 and the second composite biological tank 4, as well as the waste gas generated by anaerobic tank 1 and anoxic tank 2;

[0034] The composite biological carrier 14 component 5 is loaded with aerobic microorganisms on its surface, and the membrane fiber surface of the MABR membrane component 7 is loaded with aerobic microorganisms, anoxic microorganisms and anaerobic microorganisms from the inside to the outside, so as to achieve simultaneous nitrification and denitrification.

[0035] Optionally, an inlet pipe is provided on the upstream side of the anaerobic tank 1 for inputting sewage, and the downstream side of the anaerobic tank 1 is connected to the anoxic tank 2 through a pipeline; a first stirrer is provided in the anaerobic tank 1 to promote full contact between the sewage in the tank and the anaerobic granular sludge; a first exhaust pipe 8 is provided at the top of the anaerobic tank 1 for discharging the exhaust gas generated by the anaerobic treatment.

[0036] Optionally, the bottom of the anoxic tank 2 is provided with a second aeration pipe and connected to an external aeration device to provide the anoxic tank 2 with a suitable amount of oxygen; the top of the anoxic tank 2 is provided with a second exhaust pipe 9 for discharging the exhaust gas generated by the anoxic treatment.

[0037] The first composite biological treatment tank is equipped with a nitrification liquid return pipe, which is connected to the anoxic tank to return part of the mixed liquid from the first composite biological treatment tank to the anoxic tank.

[0038] A sedimentation tank is located downstream of the second combined biological treatment tank. A sludge return pipe is installed at the bottom of the sedimentation tank, connecting to the anoxic tank to return some of the sludge. A conventional sedimentation tank is sufficient.

[0039] Optionally, an effluent pool is provided on the downstream side of the sedimentation tank, and the overflow effluent from the top of the sedimentation tank is fed into the effluent pool. A dosing device is provided in the effluent area to add coagulants and flocculants to react with the water and ensure that the total phosphorus in the effluent meets the standards.

[0040] Optionally, the first composite biological tank 3 is a cuboid with water entering from the upper part of one side and water exiting from the lower part of the other side. Several first baffles 10 are arranged along the length direction, so that the sewage flows through the length direction of the first composite biological tank 3 in a tortuous manner. A composite biological carrier 14 component 5 is provided between two adjacent first baffles 10.

[0041] The bottom of the first composite biological tank 3 is provided with a first aeration pipe 6. The first aeration pipe 6 passes through each of the first baffles 10 and is evenly distributed at the bottom of the first composite biological tank 3. The first aeration pipe 6 is located below the composite biological carrier 14 component 5. An external aeration device is connected to the first aeration pipe 6 to provide oxygen to the first composite biological tank 3.

[0042] Optionally, the second composite biological tank 4 is a cuboid, and several second baffles 11 are arranged along the length direction, so that the sewage flows up and down through the length direction of the second composite biological tank 4 in a tortuous manner, and a MABR membrane module 7 is provided between two adjacent second baffles 11.

[0043] If water enters the lower part of one side of the second composite biological tank 4, water will exit the upper part of the other side; if water enters the upper part of one side of the second composite biological tank 4, water will exit the lower part of the other side.

[0044] Optionally, both the first baffle 10 and the second baffle 11 are vertical, flat solid plates.

[0045] The top of the first baffle plate 10 is fixedly connected to the top wall of the first composite biological treatment tank 3, while the bottom is suspended, or the bottom is fixedly connected to the bottom surface of the first composite biological treatment tank 3, while the top is suspended, so that the sewage flows in a tortuous manner in the first composite biological treatment tank 3.

[0046] The top of the second baffle plate 11 is fixedly connected to the top wall of the second composite biological treatment tank 4, while the bottom is suspended, or the bottom is fixedly connected to the bottom surface of the second composite biological treatment tank 4, while the top is suspended, so that the sewage flows in a tortuous manner in the second composite biological treatment tank 4.

[0047] In one specific implementation, the top of the first baffle plate 10 closest to the anoxic tank 2 in the first composite biological tank 3 is fixedly connected to the top wall of the first composite biological tank 3, while the bottom is suspended. Sewage enters the upper part of the first composite biological tank 3, is blocked by the first baffle plate 10, and flows from top to bottom. Then it flows through the gap between the bottom of the first baffle plate 10 and the bottom surface of the first composite biological tank 3, and then flows from bottom to top. The top of the second baffle plate 10 is suspended, while the bottom is fixedly connected to the bottom surface of the first composite biological tank 3. Sewage then flows through the gap between the top of the second baffle plate 10 and the top wall of the first composite biological tank 3, and then flows from top to bottom. The top of the third baffle plate 10 is fixedly connected to the top wall of the first composite biological tank 3, while the bottom is suspended. Sewage then flows through the gap between the bottom of the third baffle plate 10 and the bottom surface of the first composite biological tank 3, and so on.

[0048] The second baffle plate 11 in the second composite biochemical tank 4 is set in the manner described above.

[0049] Optionally, the composite biological carrier 14 component 5 includes an upper support 12, several biological carriers 14 and a lower support 13. The top end of the biological carrier 14 is fixed on the upper support 12 and the bottom end is fixed on the lower support 13. Several biological carriers 14 are evenly arranged in a matrix between the upper support 12 and the lower support 13 in several rows and columns.

[0050] The biological carrier 14 includes at least two spirally wound willow twigs 16 and several soft sponges 15 between the willow twigs 16. The willow twigs 16 are relatively thin and flexible, and the fibers are relatively fine.

[0051] Further optionally, the willow twigs 16 have an average diameter of 1-5 mm, the soft sponge 15 has a particle size of 3-8 mm, and several soft sponge pieces 15 are evenly distributed between two wound willow twigs 16. The soft sponge 15 is fixed by the force of the winding and is prevented from being washed away by the sewage flow.

[0052] Optionally, the biological carrier 14 is prepared by the following method:

[0053] (1) Immerse the willow twig 16 entirely in the ethanol solution so that the willow twig 16 is fully wetted;

[0054] (2) Immerse the entire willow twig 16 in an acidic solution, soak it thoroughly, and then wash it with an ethanol solution until it is neutral;

[0055] (3) Immerse the willow twig 16 in an alkaline solution, soak it thoroughly, and then rinse it with an ethanol solution until it is neutral.

[0056] (4) The willow twigs 16 obtained in step (3) are spirally intertwined with each other, and several soft sponges 15 are evenly placed therein to make the biological carrier 14.

[0057] Further optionally, the concentration of the ethanol solution is 45-64 vol%; the acidic solution is selected from one of nitric acid solution, hydrochloric acid solution, phosphoric acid solution, and sulfuric acid solution, and the concentration of the acidic solution is 10-20 wt%; the alkaline solution is selected from one of NaOH and KOH, and the concentration of the alkaline solution is 15-25 wt%.

[0058] Further optional, in the soaking or immersion steps of steps (1)-(3), ultrasonic treatment is used. Specifically, the willow twigs 16 and the corresponding solution are placed in a container, and then the container is placed in a water tank. An ultrasonic plate is provided on the side of the water tank, and the water tank is filled with water. Ultrasonic treatment promotes the soaking of the willow twigs 16.

[0059] Further optionally, in step (1), no more bubbles appear on the surface of the willow twig 16, which indicates that it is fully soaked; the soaking time in steps (2) and (3) is 12-24h.

[0060] Willow twigs 16 are thoroughly soaked in an ethanol solution to expel air bubbles from their surface and internal pores, facilitating the introduction of subsequent acidic and alkaline solutions into the plant tissue. When fully soaked, the willow twigs 16 are immersed in an acidic solution; the acid penetrates the plant tissue, dissolving some tissue components and creating irregular micropores on the surface. Subsequently, the willow twigs 16 are soaked in an alkaline solution; the alkaline solution penetrates the plant tissue, dissolving other tissue components with different properties, resulting in irregular micropores on the surface. This acid- and alkaline soaking process creates micropores or an uneven surface on the willow twigs 16, increasing their specific surface area and thus enhancing the microbial loading capacity.

[0061] Willow twigs 16 are slender and long, with good flexibility, making them durable and resistant to breakage as a biological carrier 14. Even if broken, they can be repaired by binding together other willow twigs 16. The thinness of the willow twigs 16 facilitates their clustering. Combined with acid-alkali treatment, the surface of the willow twigs 16 develops micropores or an uneven microstructure, making them an excellent biological carrier 14. Two willow twigs 16 are intertwined like braids, with a small piece of soft sponge 15 firmly wrapped between them, resulting in minimal leakage. The soft sponge 15 has a highly porous structure, making it a high-performance biological carrier 14. The biological carrier 14 formed by the treated willow twigs 16 and soft sponge 15 has a unique structure and is an original invention. Compared to traditional plastic carriers, it has a higher microbial loading capacity, is durable, environmentally friendly, and biodegradable after disposal.

[0062] After passing through anaerobic tank 1 and anoxic tank 2, the wastewater enters the first composite biological treatment tank 3. Aerobic microorganisms are loaded on each willow branch 16 and soft sponge 15, enabling the wastewater to undergo an anaerobic-anoxic-aerobic treatment process.

[0063] Optionally, the MABR membrane module 7 is placed vertically, parallel to the composite biological carrier 14 module 5. The bottom of the MABR membrane module 7 is for air intake, and a pressure gauge is provided at the top. The second composite biological tank 4 is equipped with a dissolved oxygen meter to measure the dissolved oxygen concentration of the second composite biological tank 4. The MABR membrane module 7 is a hollow fiber curtain membrane.

[0064] External aeration devices are connected to the bottom of each MABR membrane module 7 to provide oxygen to the MABR membrane module 7.

[0065] Oxygen or air is introduced into the membrane fibers of MABR membrane module 7, and the gas then overflows from the membrane pores, achieving bubble-free aeration. The outer surface of the membrane is loaded with aerobic, anoxic, and anaerobic microorganisms from the inside out, achieving simultaneous nitrification and denitrification. This not only effectively reduces the volume of the reaction tank but also allows for the rapid utilization of nitrate, a product of nitrification, as a substrate during the reaction. This helps to address the inhibition of nitrate accumulation on the nitrification reaction and accelerates the nitrification process. Furthermore, the alkalinity generated during denitrification helps maintain the alkalinity balance within the system to a certain extent. Simultaneously, the bubble-free aeration of MABR membrane module 7 improves oxygen transfer rate and oxygen utilization, and effectively avoids sludge bulking. The membrane fibers also serve as microbial carriers 14, loading different types of microorganisms based on the varying oxygen content on the membrane fiber surface, achieving simultaneous nitrification and denitrification treatment.

[0066] The second composite biological treatment tank 4 is an oxygen-limited aeration tank, where dissolved oxygen needs to be controlled below 0.3 mg / L. This reduces the demand for carbon sources. After the wastewater undergoes anaerobic, anoxic, and aerobic treatment in the first composite biological treatment tank 3, the organic pollutants in the wastewater are reduced, i.e., the carbon source is reduced. At this point, the wastewater is suitable for the second composite biological treatment tank 4, which improves the nitrogen and phosphorus removal efficiency.

[0067] The waste gas generated from anaerobic tank 1 and anoxic tank 2 is introduced into the first composite biological tank 3 and the second composite biological tank 4. Some of the waste gas is removed by biochemical action, such as absorbing H2S and NH3 in the waste gas, reducing the escape of odor and reducing the cost of waste gas treatment. At the same time, it promotes the utilization of organic carbon sources by microorganisms in the anaerobic zone and the further release of phosphorus.

[0068] Optionally, the enhanced nitrogen and phosphorus removal wastewater treatment device further includes a sludge regeneration unit, including a decalcification tank 17, a regeneration tank 18, and a deaeration tank 24. The top of the decalcification tank 17 is provided with a sludge inlet and an acid addition inlet, and the bottom is provided with a decalcification inlet 19. The bottom of the anaerobic tank 1 is provided with a sludge discharge outlet, which is connected to the sludge inlet through a pipe and a sludge pump. The acid addition inlet is used to add phosphoric acid decalcification agent.

[0069] Downstream of the first composite biological treatment tank 3, a deoxygenation tank 24 and a regeneration tank 18 are arranged in sequence. Downstream of the regeneration tank 18 is the second composite biological treatment tank 4. The decalcified granular sludge in the decalcification tank 17 is fed into the regeneration tank 18. The wastewater treated by the first composite biological treatment tank 3 is also fed into the regeneration tank 18 after being deoxygenated by the deoxygenation tank 24.

[0070] Optionally, the decalcification tank 17 is equipped with a second stirrer to promote the full reaction between the calcified granular sludge and the phosphoric acid solution to generate calcium phosphate. Under the stirring action, the calcium phosphate is separated from the granular sludge.

[0071] The upper part of the decalcification tank 17 is equipped with a sewage outlet 20 for real-time discharge of water containing calcium phosphate precipitate. After filtration and separation, the water can be returned to the decalcification tank 17, and the calcium phosphate is treated separately.

[0072] Optionally, the inlet of the deoxygenation tank 24 is connected to the outlet of the first composite biological tank 3, and the outlet of the deoxygenation tank 24 is connected to the inlet of the regeneration tank 18. Aquatic plants and phytoplankton are planted in the deoxygenation tank 24, and the top surface of the deoxygenation tank 24 is equipped with an openable and closable top plate to provide an intermittent closed environment for the deoxygenation tank. When closed, it prevents sunlight from entering the deoxygenation tank 24 and promotes the rapid consumption of dissolved oxygen in the water by the plants in the deoxygenation tank 24.

[0073] Optionally, the regeneration tank 18 is provided with an inlet, a first sludge inlet 21, and a second sludge inlet 22 on the side near the deoxygenation tank 24, and an outlet and a third sludge inlet 23 on the side near the second composite biological treatment tank 4.

[0074] The outlet of the regeneration tank 18 is connected to the inlet of the second composite biological tank 4; the decalcification port 19 of the decalcification tank 17 is connected to the first sludge port 21, which inputs the decalcified sludge; the second sludge port 22 is connected to the anaerobic tank 1, which is used to input the activated sludge from the anaerobic tank 1 into the regeneration tank 18; and the third sludge port 23 is connected to the anaerobic tank 1, which is used to return the regenerated anaerobic granular sludge to the anaerobic tank 1.

[0075] When the treatment effect of anaerobic tank 1 decreases during operation, the degree of calcification of the granular sludge is tested by sampling. If calcification is severe, decalcification is required. The calcified granular sludge in anaerobic tank 1 is discharged into decalcification tank 17. In decalcification tank 17, phosphoric acid reacts with the sludge to form calcium phosphate precipitate. After the reaction, the calcium phosphate precipitate is lighter than the granular sludge and, under stirring, most of it is located in the upper part of the decalcification tank. The calcium phosphate precipitate and water are discharged from the discharge port 20. The discharge port 20 is connected to a waste tank through a pipe. The outlet of the waste tank is equipped with a filter screen and is connected to the sludge inlet or acid inlet of the decalcification tank through a pipe, leaving the calcium phosphate precipitate in the waste tank for further treatment. The water is recycled back to the decalcification tank. Then, the decalcified granular sludge and water from the decalcification tank are discharged into the regeneration tank 18 through the decalcification port 19.

[0076] The wastewater treated in the first composite biological treatment tank 3 has a high oxygen content and is fed into the deoxygenation tank 24. There, plants consume a large amount of the oxygen in the dark environment, reducing the oxygen content of the wastewater before it is fed into the regeneration tank 18. The deoxygenation tank 24 can be used as an ornamental tank, where fish can be raised depending on the water quality to promote oxygen consumption. Several baffles can be installed inside the deoxygenation tank 24 to create a tortuous flow channel and extend the residence time.

[0077] The wastewater, activated sludge, and decalcified granular sludge from deoxygenation tank 24 are all fed into regeneration tank 18. Regeneration tank 18 is equipped with agitator or pneumatic agitator. The wastewater provides nutrients for the microbial cultivation of the granular sludge, further removing pollutants. Then, the wastewater, carrying a small amount of anaerobic sludge, enters the second combined biological treatment tank 4. Since both combined biological treatment tanks operate continuously, the wastewater in deoxygenation tank 24 and regeneration tank 18 is also continuously flowing, constantly providing wastewater to the decalcified granular sludge, alleviating nutrient deficiency and meeting the needs of long-term granular sludge cultivation. The cultivated anaerobic granular sludge is returned to anaerobic tank 1 for further anaerobic treatment.

[0078] This embodiment provides an example of the preparation of a biological carrier, serving as a demonstration:

[0079] (1) Immerse the willow twigs in a 45 vol% ethanol solution until no more bubbles appear on the surface of the willow twigs, so that the willow twigs are fully moistened;

[0080] (2) Immerse the willow twigs in a 10wt% hydrochloric acid solution for 24 hours, then wash them with a 45vol% ethanol solution until neutral.

[0081] (3) Immerse the willow twigs in a 15wt% NaOH solution for 24 hours, then rinse with a 45vol% ethanol solution until neutral.

[0082] The above steps (1)-(3) are all intermittent ultrasound treatments, with ultrasound every 1 hour, each ultrasound lasting 30 minutes, and the power being 60kw;

[0083] (4) The two willow twigs obtained in step (3) are placed on both sides of the hollow fiber membrane filaments, and the three are parallel. The length of the willow twigs and the hollow fiber membrane filaments is 50cm, the average diameter of the willow twigs is 5mm, and the hollow fiber membrane filaments are the same as the membrane filaments of the MABR membrane module.

[0084] Then, two willow twigs are alternately spirally wound around hollow fiber membrane filaments, and 75 soft sponges with a particle size of 4-6 mm are evenly placed between the willow twigs and hollow fiber membrane filaments to obtain the biological carrier.

Claims

1. A wastewater treatment device for enhanced nitrogen and phosphorus removal, characterized in that, It includes an anaerobic tank, an anoxic tank, a first composite biochemical tank, and a second composite biochemical tank connected in sequence. The first composite biochemical tank is equipped with several composite biological carrier components and a first aeration pipe. The second composite biochemical tank is equipped with several MABR membrane components. The anaerobic tank is equipped with a first waste gas pipe, and the outlet of the first waste gas pipe is equipped with several first branch pipes, which are respectively connected to the first aeration pipe and several MABR membrane modules; the anoxic tank is equipped with a second waste gas pipe, and the outlet of the second waste gas pipe is equipped with several second branch pipes, which are respectively connected to the first aeration pipe and several MABR membrane modules; the external aeration device is connected in parallel with the first aeration pipe and several MABR membrane modules through the air path to provide oxygen to the first composite biological tank and the second composite biological tank, as well as the waste gas generated by the anaerobic tank and the anoxic tank; The composite biological carrier component is loaded with aerobic microorganisms on its surface, and the membrane fiber surface of the MABR membrane component is loaded with aerobic microorganisms, anoxic microorganisms and anaerobic microorganisms from the inside to the outside, so as to achieve simultaneous nitrification and denitrification. The composite biological carrier assembly includes an upper support, several biological carriers and a lower support. The top end of the biological carrier is fixed on the upper support and the bottom end is fixed on the lower support. Several biological carriers are arranged in a matrix of several rows and several columns between the upper support and the lower support. The biological carrier consists of at least two spirally intertwined willow branches and several soft sponges between the willow branches; The preparation method of the biological carrier is as follows: (1) Immerse the willow twigs entirely in the ethanol solution to ensure they are fully soaked; (2) Immerse the willow twigs in an acidic solution until fully soaked, then wash with an ethanol solution until neutral; (3) Immerse the willow twigs in an alkaline solution until fully soaked, then rinse with an ethanol solution until neutral. (4) The willow twigs obtained in step (3) are spirally intertwined with each other, and several soft sponges are evenly placed in them to obtain the biological carrier; The enhanced nitrogen and phosphorus removal wastewater treatment device also includes a sludge regeneration unit, comprising a decalcification tank, a regeneration tank, and a deoxygenation tank. The top of the decalcification tank is equipped with a sludge inlet and an acid addition inlet, and the bottom is equipped with a decalcification inlet. The bottom of the anaerobic tank is equipped with a sludge discharge inlet, which is connected to the sludge inlet via a pipe and a sludge pump. The acid addition inlet is used to add phosphoric acid decalcification agent. Downstream of the first composite biological treatment tank, a deoxygenation tank and a regeneration tank are set up in sequence. Downstream of the regeneration tank is the second composite biological treatment tank. The decalcified granular sludge from the decalcification tank is fed into the regeneration tank. The wastewater treated by the first composite biological treatment tank is also fed into the regeneration tank after being deoxygenated in the deoxygenation tank.

2. The wastewater treatment device for enhanced nitrogen and phosphorus removal according to claim 1, characterized in that, The first composite biological treatment tank is a cuboid with water entering from the upper part of one side and exiting from the lower part of the other side. Several first baffles are arranged along the length direction, so that the sewage flows through the length direction of the first composite biological treatment tank in a tortuous manner. A composite biological carrier component is provided between two adjacent first baffles. The bottom of the first composite biological tank is provided with a first aeration pipe. The first aeration pipe passes through each of the first baffles and is evenly distributed at the bottom of the first composite biological tank. The first aeration pipe is located below the composite biological carrier component. An external aeration device is connected to the first aeration pipe to provide oxygen to the first composite biological tank.

3. The wastewater treatment device for enhanced nitrogen and phosphorus removal according to claim 2, characterized in that, The second composite biological treatment tank is a cuboid, and several second baffles are arranged along its length, so that the sewage flows through the length of the second composite biological treatment tank in a tortuous manner. A MABR membrane module is provided between two adjacent second baffles.

4. The wastewater treatment device for enhanced nitrogen and phosphorus removal according to claim 1, characterized in that, The willow twigs have an average diameter of 1-5 mm, and the soft sponges have a particle size of 3-8 mm. Several pieces of soft sponges are evenly distributed between two intertwined willow twigs.

5. The wastewater treatment device for enhanced nitrogen and phosphorus removal according to claim 3, characterized in that, The MABR membrane module is placed vertically, parallel to the composite biological carrier module. The bottom of the MABR membrane module is for air intake, and the top is equipped with a pressure gauge. A dissolved oxygen meter is installed in the second composite biological tank to measure the dissolved oxygen concentration in the second composite biological tank. The MABR membrane module is a hollow fiber curtain membrane. External aeration devices are connected to the bottom of each MABR membrane module to provide oxygen to the MABR membrane module.

6. The wastewater treatment device for enhanced nitrogen and phosphorus removal according to claim 1, characterized in that, The inlet of the deoxygenation tank is connected to the outlet of the first composite biological tank, and the outlet of the deoxygenation tank is connected to the inlet of the regeneration tank. Aquatic plants and phytoplankton are planted in the deoxygenation tank. The top surface of the deoxygenation tank is equipped with an openable and closable top plate to provide an intermittent sealed environment for the deoxygenation tank. When sealed, it prevents sunlight from entering the deoxygenation tank and promotes the rapid consumption of dissolved oxygen in the water by the plants in the deoxygenation tank.

7. The wastewater treatment device for enhanced nitrogen and phosphorus removal according to claim 6, characterized in that, The regeneration tank is provided with an inlet, a first sludge outlet, and a second sludge outlet on the side near the first composite biological treatment tank, and an outlet and a third sludge outlet on the side near the second composite biological treatment tank. The outlet of the regeneration tank is connected to the inlet of the second composite biological treatment tank; the decalcification outlet of the decalcification tank is connected to the first sludge inlet, and decalcified sludge is fed in. The second sludge inlet connects to the anaerobic tank and is used to input the activated sludge from the anaerobic tank into the regeneration tank. The third sludge inlet connects to the anaerobic tank and is used to return the regenerated anaerobic granular sludge to the anaerobic tank.

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