A wastewater denitrification device and a denitrification method

Abstract

The present invention provides a wastewater denitrification device and a denitrification method, belonging to the technical field of wastewater denitrification. The device includes an anaerobic tower, an anoxic tank, an aerobic tank, a clarifier, a biological desulfurization filter, a methane dissolution tank, a methane anaerobic denitrification tank, a filtering device, and an aerated biological filter, which are connected in sequence through liquid pipelines. The biological desulfurization filter is divided into two stages; the anaerobic tower, the first-stage biological desulfurization filter, and the methane dissolution tank are connected in sequence through gas pipelines. This system can purify the biogas generated in the traditional wastewater anaerobic treatment system and utilize it for biological denitrification, without the need for additional carbon source addition, and realizes the screening, purification, and enrichment of methane anaerobic denitrifying bacteria, improves the effect of wastewater denitrification, reduces the operation cost, is applicable to the denitrification treatment of high-ammonia-nitrogen wastewater with a low carbon-nitrogen ratio, and can completely replace the deep denitrification system at the back end of the traditional A / O process.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater treatment, and particularly relates to a wastewater denitrification device and a denitrification method. Background Art

[0002] In traditional denitrification processes, the anoxic / aerobic process plays a very important role. However, due to the low carbon-nitrogen ratio (BOD / TN) in many wastewaters, additional carbon sources need to be supplemented to ensure the denitrification efficiency. In addition, traditional anoxic / aerobic systems generally do not have effective means for enriching and purifying the denitrifying microbial system. The denitrifying microorganisms often account for a relatively low ratio in the overall microbial community, resulting in the carbon source supplemented not being specifically used for the denitrification reaction, causing a decrease in denitrification efficiency and waste of carbon sources.

[0003] Methanotrophic anaerobic denitrifying microorganisms can utilize NO2 - -N and NO3 - -N as electron acceptors and methane as an electron donor for simultaneous anaerobic denitrification and anaerobic methane oxidation. Methanotrophic anaerobic denitrifying bacteria can specifically utilize methane as the sole carbon source to remove nitrate nitrogen (nitrite nitrogen), which is an economically saving anaerobic denitrification technology with great development potential. However, current research findings show that methanotrophic anaerobic denitrifying bacteria grow slowly and are difficult to enrich in traditional anaerobic systems. Moreover, the solubility of methane in water is too low, resulting in generally low anaerobic denitrification efficiency and low denitrification efficiency of wastewater during the wastewater treatment process. Summary of the Invention

[0004] In view of the above problems existing in the prior art, the present invention provides a wastewater denitrification device and a denitrification method. While the denitrification device is performing denitrification, it can achieve desulfurization treatment of the biogas generated in the traditional wastewater treatment device without the need to additionally set up a biogas purification device. At the same time, the device can achieve enrichment of methanotrophic anaerobic denitrifying bacteria and improve the denitrification effect of wastewater by using methanotrophic anaerobic denitrifying bacteria and biogas. This device is applicable to the denitrification of wastewater with a B / C (BOD / COD) lower than 0.3, a B / N (BOD / TN) ratio lower than 2.8, and a TN content lower than 1000 mg / L. This system can completely or partially replace the traditional anoxic tank and can be used as a deep denitrification process.

[0005] To achieve the above object, the technical solution adopted by the present invention to solve its technical problems is:

[0006] A wastewater denitrification device includes an anaerobic tower, an anoxic tank, an aerobic tank, and an aerated biological filter, and also includes a clarifier, a biological desulfurization filter, a methane dissolution tank, and a methanotrophic anaerobic denitrification tank;

[0007] An anaerobic tower, an anoxic tank, an aerobic tank, a clarifier, a biological desulfurization filter, a methane dissolution tank, a methane anaerobic denitrification tank, and an aerated biological filter are sequentially connected through liquid pipelines. The biological desulfurization filter is also connected to the methane anaerobic denitrification tank through a liquid pipeline;

[0008] The anaerobic tower, the biological desulfurization filter, and the methane dissolution tank are sequentially connected through gas pipelines;

[0009] The methane anaerobic denitrification tank is provided with a methane anaerobic denitrification bacteria packing area and a filtering device. The filtering device is arranged above the methane anaerobic denitrification bacteria packing area. The filtering device is connected to the aerated biological filter through a pipeline, and the methane dissolution tank is connected to the filtering device through a gas pipeline.

[0010] Furthermore, a desulfurization microorganism packing is arranged in the middle of the biological desulfurization filter. A water distributor and an air outlet pipe are arranged above the desulfurization microorganism packing, and an air inlet pipe and a water outlet pipe are arranged below the desulfurization microorganism packing.

[0011] Furthermore, the biological desulfurization filter is provided with two stages, including a primary desulfurization filter and a secondary desulfurization filter. The air inlet pipe of the primary desulfurization filter is connected to the anaerobic tower, the water distributor of the primary desulfurization filter is connected to the aerated biological filter, the air outlet pipe of the primary desulfurization filter is connected to the air inlet pipe of the secondary desulfurization filter, and the water outlet pipe of the primary desulfurization filter is connected to the anoxic tank;

[0012] The water distributor of the secondary desulfurization filter is connected to the clarifier. Two water outlet pipes are arranged at the bottom of the secondary desulfurization filter. The air outlet pipe and one of the water outlet pipes are connected to the methane dissolution tank through a dissolved air pump, and the other water outlet pipe is connected to the methane anaerobic denitrification bacteria packing area in the methane anaerobic denitrification tank.

[0013] Furthermore, a sealing cylinder is arranged in the methane anaerobic denitrification tank. A pressurized area is formed inside the sealing cylinder. The methane anaerobic denitrification bacteria packing area is arranged around the sealing cylinder. The pressurized area is connected to the methane anaerobic denitrification bacteria packing area through a sludge release pipe;

[0014] The filtering device is arranged above the sealing cylinder. A liquid pipeline is arranged between the filtering device and the aerated biological filter, and a sludge flow pipe is arranged between the filtering device and the pressurized area.

[0015] Furthermore, a casing with an open top is arranged inside the sealing cylinder. The casing is hermetically connected to the bottom of the sealing cylinder. A dissolved air and water release head is arranged at the bottom of the casing. The dissolved air and water release head is connected to the methane dissolution tank, and the free end of the sludge flow pipe is arranged above the dissolved air and water release head.

[0016] Furthermore, a tube cylinder with an open top is arranged inside the methane anaerobic denitrification tank, and the filtering device is arranged inside the tube cylinder.

[0017] Further, the water outlet pipe of the primary desulfurization filter tank is also connected to the methane anaerobic denitrification bacteria packing area in the methane anaerobic denitrification tank.

[0018] A wastewater denitrification method uses the above denitrification device for denitrification treatment, which specifically includes the following steps:

[0019] (1) The nitrified muddy water mixture in the aerobic tank is introduced into the clarifier for muddy water separation to obtain clear liquid and sludge;

[0020] (2) The clear liquid in step (1) and the biogas generated in the anaerobic tower are simultaneously introduced into the biological desulfurization filter tank. The desulfurization microorganisms are used to remove hydrogen sulfide in the biogas and dissolved oxygen in the clear liquid, and at the same time reduce the pH of the clear liquid to facilitate anaerobic denitrification, obtaining treated biogas and clear liquid;

[0021] (3) The biogas and part of the clear liquid obtained in step (2) are introduced into the methane dissolution tank through a dissolved air pump to dissolve methane in the clear liquid to prepare a supersaturated methane-soda water mixture;

[0022] (4) The supersaturated methane-soda water mixture in step (3) is introduced into the methane anaerobic denitrification tank. Under the action of methane anaerobic denitrification bacteria in the methane anaerobic denitrification bacteria packing area, the purpose of denitrifying the clear liquid is achieved;

[0023] (5) The effluent after denitrification treatment in step (4) is filtered by a filtering device and then discharged into an aerated biological filter to remove residual pollutants; a large amount of sludge containing methane anaerobic denitrification bacteria is intercepted by the filtering device. The sludge is discharged into the sleeve in the pressurized area through a sludge circulation pipe and mixed with the continuously introduced supersaturated methane-soda water mixture to improve the anaerobic denitrification efficiency. The pressurized muddy water mixture is released to the methane anaerobic denitrification bacteria packing area through a sludge release pipe. A large number of methane bubbles are generated during the release process, further increasing the mass transfer efficiency of methane and improving the anaerobic denitrification treatment efficiency.

[0024] Further, in step (2), the dissolved oxygen in the clear liquid is controlled below 0.3 mg / L, and the pH of the clear liquid is reduced to 6.0 - 6.5; in step (3), methane is dissolved in the clear liquid under the high pressure of 0.5 - 0.6 Mpa.

[0025] Further, when the pH in the methane anaerobic denitrification bacteria packing area is higher than 7.5, a part of the acidic clear liquid in the biological desulfurization filter tank is pumped into the methane anaerobic denitrification bacteria packing area to keep the pH in the methane anaerobic denitrification packing area at 6.0 - 6.5 to improve the anaerobic denitrification efficiency.

[0026] The beneficial effects produced by the present invention are:

[0027] 1. An anaerobic microbial denitrification device is added to the traditional wastewater treatment system in this application. This anaerobic microbial denitrification device can be ingeniously combined with the traditional wastewater treatment system, further improving the denitrification effect of the traditional wastewater treatment system by using the denitrification of methane anaerobic denitrifying bacteria, and can use the biogas generated in the anaerobic tank of the traditional wastewater treatment system as the carbon source for anaerobic denitrification, without the need to additionally supplement the carbon source during the anaerobic denitrification process. At the same time, this device can also achieve the purification of biogas, eliminating the need to separately set up a biogas purification device. The coupling of this anaerobic microbial denitrification device and the traditional sewage treatment system can effectively reduce the equipment investment and operating costs of the overall sewage treatment system.

[0028] 2. The denitrification device is equipped with a biological desulfurization filter. Desulfurizing microorganisms are inoculated in the biological desulfurization filter. The desulfurizing microorganisms can use the dissolved oxygen in the clarified liquid to oxidize and remove the hydrogen sulfide gas in the biogas, achieving the purification treatment of biogas, while increasing the methane concentration, and avoiding the blockage of the subsequent filtration device caused by the formation of sulfur elemental particles after the oxidation of hydrogen sulfide in the anaerobic denitrification reactor. While removing the hydrogen sulfide gas, the biological desulfurization filter reduces the pH of the clarified liquid entering the methane anaerobic denitrification tank, which is beneficial to the progress of the anaerobic denitrification reaction and improves the anaerobic denitrification efficiency.

[0029] 3. The desulfurized biogas and the deoxygenated clarified liquid are introduced into the methane dissolution tank, creating a high-pressure environment in the methane dissolution tank, increasing the solubility of methane gas in the clarified liquid, forming a supersaturated methane-soda water mixture. When the supersaturated methane-soda water mixture is released in the methane anaerobic denitrification tank, methane gas is released from the clarified liquid, generating fine methane bubbles, which can improve the mass transfer efficiency between methane and microorganisms in the sludge, and thus improve the denitrification efficiency of microorganisms. The undissolved methane gas in the methane dissolution tank can also be used for air washing the filtration device to reduce the occurrence of blockage of the filtration device and improve the filtration effect.

[0030] 4. The methane anaerobic denitrification tank is innovatively provided with a pressurized area. The reflux sludge undergoes a pressurized contact reaction with the supersaturated methane-soda water mixture introduced into the pressurized area, increasing the contact efficiency between microorganisms and methane, enabling methane to fully adhere to the surface of microbial cells, ensuring that the surface of microbial cells is saturated with adsorbed methane. After being released into the filler area of methane anaerobic denitrifying bacteria and coming into contact with nitrate nitrogen in the water, it can quickly carry out anaerobic denitrification reaction. The setting of the pressurized area greatly improves the anaerobic denitrification efficiency and reduces the volume of the methane anaerobic denitrification tank at the same time.

[0031] 5. There is a methane anaerobic denitrification bacteria packing area in the methane anaerobic denitrification tank. When the sludge and methane steam-water mixture in the pressurized area are released into the methane anaerobic denitrification bacteria packing area, the pressure further decreases, causing the dissolved methane in the clear liquid to be further released, generating fine bubbles, increasing the mass transfer efficiency, and improving the denitrification efficiency of microorganisms. The sludge and steam-water mixture passing through the methane anaerobic denitrification bacteria packing area, under the filtration and collision effects of the packing, make the smaller bubbles attached to the sludge surface become larger bubbles, thus realizing the degassing of the sludge. Part of the degassed sludge is intercepted in the packing layer, and part enters the filter tube barrel with the water. The mud-water separation is achieved through filtration. The separated clear liquid can continue to enter the biological aerated filter for treatment to ensure the effluent meets the standards. A large amount of methane anaerobic denitrification bacteria are contained in the intercepted sludge. The sludge is continuously returned to the pressurized area to be mixed with the supersaturated methane steam-water mixture for recycling, effectively avoiding the loss of denitrifying bacteria. The methane anaerobic denitrification tank increases the enrichment effect of methane anaerobic denitrification bacteria and improves the denitrification effect on the clear liquid. Description of the Drawings

[0032] Figure 1 is the process flow chart of the present invention;

[0033] Figure 2 is the structural schematic diagram of the device of the present invention;

[0034] Figure 3 is the structural schematic diagram of the sludge release pipe of the methane anaerobic denitrification tank.

[0035] Reference numerals: 1. Clarifier; 2. Biological desulfurization filter; 3. Methane dissolution tank; 4. Methane anaerobic denitrification tank; 5. Methane anaerobic denitrification bacteria packing area; 6. Filter device; 7. Desulfurization microorganism packing; 8. Primary desulfurization filter; 9. Secondary desulfurization filter; 10. Dissolved air pump; 11. Sealing cylinder; 12. Pressurized area; 13. Sludge release pipe; 14. Sludge circulation pipe; 15. Sleeve; 16. Dissolved steam-water release head; 17. Tube barrel; 18. Pressure gauge 1; 19. Liquid level gauge 1; 20. Liquid level gauge 2; 21. Pressure gauge 2; 22. pH meter; 23. Gas guide pipe. Detailed Embodiments

[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention, that is, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.

[0037] Accordingly, the following detailed description of the provided embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0038] It should be noted that relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising a..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0039] The features and performance of the present invention will be further described in detail below in conjunction with embodiments and drawings.

[0040] A wastewater denitrification device includes an anaerobic tower, an anoxic tank, an aerobic tank and an aerated biological filter, and further includes a clarifier 1, a biological desulfurization filter 2, a methane dissolution tank 3 and a methane anaerobic denitrification tank 4;

[0041] The anaerobic tower, the anoxic tank, the aerobic tank, the clarifier 1, the biological desulfurization filter 2, the methane dissolution tank 3, the methane anaerobic denitrification tank 4 and the aerated biological filter are sequentially connected in series through liquid pipelines, and the biological desulfurization filter 2 is also connected to the methane anaerobic denitrification tank 4 through a liquid pipeline; the anaerobic tower, the biological desulfurization filter 2 and the methane dissolution tank 3 are sequentially connected in series through gas pipelines;

[0042] A methane anaerobic denitrification bacteria packing area 5 and a filtering device 6 are arranged in the methane anaerobic denitrification tank 4, the filtering device 6 is arranged above the methane anaerobic denitrification bacteria packing area 5, and the filtering device 6 is connected to the aerated biological filter through a pipeline.

[0043] Optimally, a desulfurization microbial packing 7 is arranged in the middle of the biological desulfurization filter tank 2. The desulfurization microorganisms inoculated in the packing can utilize the dissolved oxygen in the clarified liquid to convert the hydrogen sulfide gas in the biogas into elemental sulfur, achieving the removal of the hydrogen sulfide gas. At the same time, the dissolved oxygen in the clarified liquid is also removed. Above the desulfurization microbial packing 7, a water distributor and an air outlet pipe are arranged. Below the desulfurization microbial packing 7, an air inlet pipe and a water outlet pipe are arranged. During use, the clarified liquid enters the biological desulfurization filter tank 2 through the water distributor and scatters on the desulfurization microbial packing 7. The biogas generated in the anaerobic tower enters through the air inlet pipe at the lower part of the desulfurization microbial packing 7. The density of the biogas gas is small and it moves upward, contacts with the clarified liquid scattered by the water distributor, and is converted into elemental sulfur under the action of the desulfurization microorganisms, achieving the purpose of removing hydrogen sulfide in the biogas and dissolved oxygen in the clarified liquid through this device;

[0044] Part of the clarified liquid and methane gas after desulfurization treatment are pumped into the methane dissolution tank 3. A spiral liquid circulation pipeline is arranged in the methane dissolution tank 3. The clarified liquid enters from the upper part of the methane dissolution tank 3. During the process of flowing downward under the action of gravity, the contact time and contact area with the methane gas can be increased, thereby improving the solubility of methane in the clarified liquid. The operating pressure of the methane dissolution tank 3 is 0.5 - 0.6 Mpa. Under the action of high pressure, the solubility of methane in the clarified liquid can be further improved, and a saturated methane soda water mixture is prepared;

[0045] Optimally, while removing hydrogen sulfide, the biological desulfurization filter tank 2 produces acidic clarified liquid with a low oxygen content, which is beneficial to the enrichment of subsequent methane anaerobic denitrifying microorganisms and anaerobic denitrification reaction. The biological desulfurization filter tank 2 can also remove part of the carbon dioxide in the biogas, increasing the methane content to 70 - 80%. Using the biological desulfurization filter tank 2 to treat the biogas does not generate new wastewater, forming a closed-loop process, which can avoid setting up a separate biogas treatment device, reducing the construction cost and floor area. A backwashing device is arranged in the device to perform backwashing regularly to remove the generated elemental sulfur;

[0046] Since the acidity of the clarified liquid discharged from the biological desulfurization filter tank 2 is relatively high and it is difficult for the subsequent anaerobic denitrification reaction to fully utilize it, two groups of biological desulfurization filter tanks 2 are provided, including a primary desulfurization filter tank 8 and a secondary desulfurization filter tank 9. The inlet gas pipe of the primary desulfurization filter tank 8 is connected to the anaerobic tower, the outlet gas pipe of the primary desulfurization filter tank 8 is connected to the inlet gas pipe of the secondary desulfurization filter tank 9, and the outlet water pipe of the primary desulfurization filter tank 8 is connected to the anoxic tank; the water distributor of the secondary desulfurization filter tank 9 is connected to the clarifier 1, and two outlet water pipes are arranged at the bottom of the secondary desulfurization filter tank 9. The outlet gas pipe and one of the outlet water pipes are connected to the methane dissolution tank 3 through the dissolved air pump 10, and the other outlet water pipe is connected to the methane anaerobic denitrification bacteria packing area in the methane anaerobic denitrification tank. Optimally, the outlet water pipe of the primary desulfurization filter tank 8 is also connected to the methane anaerobic denitrification bacteria packing area 5 in the methane anaerobic denitrification tank 4. The biogas generated by the anaerobic tower undergoes primary desulfurization treatment through the primary desulfurization filter tank 8 and then continues to be introduced into the secondary desulfurization filter tank 9 for secondary desulfurization treatment. After two-stage desulfurization, hydrogen sulfide and carbon dioxide in the biogas are fully removed; the water distributor of the primary desulfurization filter tank 8 is connected to the biological aerated filter, the clarified liquid of the biological aerated filter is used as the inlet water of the primary desulfurization filter tank 8, the clarified liquid generated by the clarifier 1 is used as the inlet water of the secondary desulfurization filter tank 9, 10-30% of the acidic clarified liquid generated by the secondary desulfurization filter tank 9 is introduced into the methane dissolution tank 3, and the rest enters the methane anaerobic denitrification bacteria packing area 5. The acidic clarified liquid generated by the primary desulfurization filter tank 8 can be discharged into the anoxic tank or used to adjust the pH in the subsequent methane anaerobic denitrification tank 4;

[0047] Optimally, a sealing cylinder 11 is arranged inside the methane anaerobic denitrification tank 4. A pressurized area 12 is formed inside the sealing cylinder 11, and the operating pressure of the pressurized area 12 is 0.2 - 0.3 Mpa. Optimally, a sleeve 15 with an open top is arranged inside the sealing cylinder 11. The sleeve 15 is hermetically connected to the bottom of the sealing cylinder 11. A dissolved water and gas release head 16 is arranged at the bottom of the sleeve 15. The dissolved water and gas release head 16 is communicated with the methane dissolution tank 3. The saturated methane water mixture in the methane dissolution tank 3 is released into the sleeve 15 through the dissolved water and gas release head 16. The saturated methane water mixture is in full pressurized contact with the reflux sludge, so that the microbial cell surface in the sludge is fully attached with the dissolved water and gas, increasing the methane utilization efficiency; the clear liquid in the sleeve gradually rises and then moves downward through the gap between the sleeve and the sealing tank. Since the pressure in the pressurized area 12 is lower than the pressure in the methane dissolution tank 3, part of the released methane gas is regularly released into the methane anaerobic denitrification bacteria packing area 5 through the gas guide pipe 23. This design can further increase the contact effect between methane in the clear liquid and the methane anaerobic denitrification bacteria; the methane anaerobic denitrification bacteria packing area 5 is arranged around the sealing cylinder 11. The pressurized area 12 and the methane anaerobic denitrification bacteria packing area 5 are communicated through a sludge release pipe 13. The mixed liquid in the pressurized area 12 is finally released into the methane anaerobic denitrification bacteria packing area 5 through the sludge release pipe 13. In the methane anaerobic denitrification bacteria packing area 5, the pressure further decreases, and the methane in the clear liquid is further released, fully reacting with the sludge attached to the packing and the suspended sludge in the packing layer. And under the collision and interception effects of the packing, the sludge is degassed and intercepted, improving the anaerobic denitrification effect;

[0048] The filtering device 6 is arranged at the upper part of the sealing cylinder 11. The filtering device 6 is generally a hollow fiber tube. Optimally, a tube cylinder 17 with an open top is arranged inside the methane anaerobic denitrification tank 4. The filtering device 6 is arranged inside the tube cylinder 17. The water level of the clear liquid passing through the methane anaerobic denitrification bacteria packing area 5 gradually rises, then enters the tube cylinder 17 and then enters the filtering device 6. Through the interception effect of the filtering device 6, the sludge containing methane anaerobic denitrification bacteria is intercepted, realizing the enrichment of methane anaerobic denitrification bacteria. Arranging the tube cylinder 17 can change the flow direction of the clear liquid and reduce the short-circuit effect of the reactor; a liquid pipeline is arranged between the filtering device 6 and the biological aerated filter to discharge the filtered clear liquid into the biological aerated filter for continuous anaerobic denitrification treatment; a sludge circulation pipe 14 is arranged between the filtering device 6 and the pressurized area 12. The free end of the sludge circulation pipe 14 is arranged above the dissolved water and gas release head 16. The sludge intercepted in the filtering device 6 is released into the sleeve 15 through the sludge circulation pipe 14, further mixing and contacting the enriched methane anaerobic denitrification bacteria with the subsequent influent in the pressurized area 12, promoting the anaerobic denitrification of the methane anaerobic denitrification bacteria. Repeating the above process, continuous denitrification treatment of the clear liquid is realized;

[0049] Preferably, the methane dissolving tank 3 is connected to the filtering device 6 through a gas pipeline. As methane and clear liquid are introduced, the content of undissolved methane gas in the methane dissolving tank 3 gradually increases. When the volume of undissolved methane in the methane dissolving tank 3 is relatively high, the undissolved methane in the methane dissolving tank 3 can be introduced into the filtering device 6 through the gas pipeline to conduct gas washing on the filtering device 6 and prevent the filtering device 6 from being blocked.

[0050] Preferably, a first pressure gauge 18, a first level gauge 19 and a second level gauge 20 are sequentially arranged in the methane dissolving tank 3 from top to bottom, a second pressure gauge 21 is arranged in the pressurization zone 12, and a pH meter 22 is arranged in the methane anaerobic denitrifying bacteria packing zone 5. The first pressure gauge 18 is used to monitor the air pressure in the methane dissolving device, the first level gauge 19 and the second level gauge 20 are used to monitor the liquid level in the methane dissolving tank 3, the second pressure gauge 21 is used to monitor the pressure in the pressurization zone 12, and the pH meter 22 is used to monitor the acidity and alkalinity in the methane anaerobic denitrifying bacteria packing zone 5. During use, when the first pressure gauge 18 detects that the pressure in the methane dissolving tank 3 exceeds 0.8 Mpa, the air dissolving pump 10 stops working and the introduction of biogas and water into the methane dissolving tank 3 stops. As water gradually flows out, the pressure in the methane air dissolving tank 3 returns to normal. Since the solubility of methane in water is relatively low, the undissolved methane gas gradually accumulates at the top of the methane dissolving tank 3, causing the actual working water level in the methane dissolving tank 3 to gradually drop. When the water level drops to the second level gauge 20, the methane gas at the top of the methane dissolving tank 3 is pumped into the filtering device 6 to conduct gas washing on the filtering device 6 with the methane gas. While releasing methane, the filtering device 6 is prevented from being blocked. As methane is released, the water level in the methane air dissolving tank gradually rises. When the water level rises to the first level gauge 19, the introduction of methane gas into the filtering device 6 stops, and the supersaturated methane water mixture in the methane dissolving tank 3 is continuously pumped into the methane anaerobic denitrifying tank 4. When the pressure in the pressurization zone 12 exceeds 0.4 Mpa, the release of the supersaturated methane water mixture or the sludge reflux can be stopped. Since the pressure in the pressurization zone 12 is lower than that in the methane dissolving tank 3, the released methane gas in the pressurization zone 12 accumulates at the top, thereby reducing the actual reaction time of the sludge. At this time, the methane gas released at the top of the pressurization zone 12 can be discharged into the lower part of the methane anaerobic denitrifying bacteria packing zone 5 through the gas guide pipe 23 to realize the utilization of methane while reducing the residual methane volume in the pressurization zone 12 and further improving the anaerobic denitrification efficiency in the pressurization zone 12.

[0051] During the anaerobic denitrification process in the methane anaerobic denitrifying bacteria packing zone 5, the pH gradually increases. At this time, the acidic clear liquid generated by the first-stage desulfurization filter tank 8 can be pumped into the methane anaerobic denitrifying bacteria packing zone 5 to reduce the pH in the methane anaerobic denitrifying bacteria packing zone 5 and improve the denitrification effect.

[0052] A wastewater denitrification method, which uses the above-mentioned denitrification device for denitrification treatment, specifically includes the following steps:

[0053] (1) The supernatant of the biological aerated filter is introduced into the first-stage desulfurization filter 8, and the biogas generated in the anaerobic tower is also introduced into the first-stage desulfurization filter 8. First, the first-stage desulfurization filter 8 performs desulfurization treatment on the biogas and deoxygenation treatment on the clear liquid to obtain acidic clear liquid and desulfurized biogas. The nitrified muddy water mixture in the aerobic tank is introduced into the clarifier 1 for mud-water separation. The separated sludge is introduced into the anoxic tank for anaerobic denitrification treatment, and the excess sludge is regularly discharged to the sludge tank. The separated clear liquid is introduced into the second-stage desulfurization filter 9, and then the biogas desulfurized by the first-stage desulfurization filter 8 is introduced into the second-stage desulfurization filter 9 for continuous desulfurization treatment. The desulfurization microorganisms in the first-stage desulfurization filter 8 and the second-stage desulfurization filter 9 are used to remove hydrogen sulfide in the biogas and dissolved oxygen in the clear liquid, and at the same time produce acidic clear liquid. 10-30% of the acidic clear liquid generated in the second-stage desulfurization filter 9 and the treated biogas are introduced into the methane dissolution tank 3 through the dissolved air pump 10. Under the high pressure of 0.5-0.6 Mpa, methane is dissolved in the clear liquid to prepare a supersaturated methane-soda water mixture. The remaining acidic clear liquid generated in the second-stage desulfurization filter 9 is introduced into the methane anaerobic denitrification tank 4;

[0054] (2) The supersaturated methane-soda water mixture is introduced into the methane anaerobic denitrification tank 4, and is released in the methane anaerobic denitrifying bacteria packing area 5 after passing through the pressurization area 12. During the release process, due to the decrease in pressure, the methane dissolved in the clear liquid is released from the clear liquid to form tiny methane bubbles to participate in the biological anaerobic denitrification reaction. Under the action of the inoculated methane anaerobic denitrifying bacteria, the purpose of denitrifying the clear liquid is achieved;

[0055] (3) After denitrification treatment, the water level of the clear liquid in the methane anaerobic denitrification tank 4 gradually rises and enters the pipe cylinder 17, and then sequentially enters the filtering device 6. After being filtered by the filtering device 6, it is discharged into the biological aerated filter for continuous anaerobic denitrification reaction; A large amount of sludge containing methane anaerobic denitrifying bacteria is intercepted by the filtering device 6, and the sludge is discharged into the sleeve 15 of the pressurization area 12 through the sludge circulation pipe 14. The continuously introduced supersaturated methane-soda water mixture in the methane dissolution tank 3 enters the pressurization area 12 to pressurize the reflux sludge, so that the sludge surface is saturated with adsorbed methane. Subsequently, the sludge and the supersaturated methane-soda water mixture are released to the methane anaerobic denitrifying bacteria packing area 5. During the release process, due to the further decrease in pressure and the blocking effect of the packing, a large number of methane bubbles are generated, further increasing the mass transfer efficiency of methane and improving the treatment efficiency of anaerobic denitrifying bacteria. Repeating the above operations, continuous denitrification operation of the clear liquid is achieved;

[0056] (4)When the pH in the methane anaerobic denitrifying bacteria packing area 5 is higher than 7.5, the acidic clear liquid in the primary desulfurization filter tank 8 is discharged into the methane anaerobic denitrifying bacteria packing area 5 to keep the environment in the methane anaerobic denitrifying packing area 5 slightly acidic and neutral, thereby improving the denitrification effect on the clear liquid.

[0057] In the above device, the average sludge age is controlled within 80 - 90 days, the mixed liquor suspended solids concentration (MLSS) is 12 - 14 g / L, the ratio of mixed liquor volatile suspended solids concentration to mixed liquor suspended solids concentration (MLVSS / MLSS) ≥ 0.65, the membrane flux of the filtration device is 8 - 15 L / m 2 ·h, and the average upward flow velocity of the water flow in the methane anaerobic denitrification tank is 0.2 - 0.5 m / h.

[0058] The above content is only an example and explanation of the structure of the present invention. Modifications, supplements, or substitutions made by those skilled in the art to the specific embodiments described without creative efforts still fall within the protection scope of this patent.

Claims

1. A wastewater denitrification device, comprising an anaerobic tower, an anoxic tank, an aerobic tank and an aerated biological filter, characterized in that, It also includes a clarifier (1), a biological desulfurization filter (2), a methane dissolution tank (3), and a methane anaerobic denitrification tank (4); The anaerobic tower, anoxic tank, aerobic tank, clarifier (1), biological desulfurization filter (2), methane dissolution tank (3), methane anaerobic denitrification tank (4), and biological aerated filter are sequentially connected through liquid pipelines. The biological desulfurization filter (2) is also connected to the methane anaerobic denitrification tank (4) through a liquid pipeline; The anaerobic tower, biological desulfurization filter (2), and methane dissolution tank (3) are sequentially connected through a gas pipeline; A methane anaerobic denitrification bacteria packing area (5) and a filtering device (6) are arranged in the methane anaerobic denitrification tank (4). The filtering device (6) is arranged above the methane anaerobic denitrification bacteria packing area (5). The filtering device (6) is connected to the biological aerated filter through a pipeline. The methane dissolution tank (3) is connected to the filtering device (6) through a gas pipeline; A sealing cylinder (11) is arranged in the methane anaerobic denitrification tank (4). A pressurized area (12) is formed inside the sealing cylinder (11). The methane anaerobic denitrification bacteria packing area (5) is arranged around the sealing cylinder (11). The pressurized area (12) is connected to the methane anaerobic denitrification bacteria packing area (5) through a sludge release pipe (13); The filtering device (6) is arranged above the sealing cylinder (11). A liquid pipeline is arranged between the filtering device (6) and the biological aerated filter. A sludge circulation pipe (14) is arranged between the filtering device (6) and the pressurized area (12); A casing (15) with an open top is arranged inside the sealing cylinder (11). The casing (15) is hermetically connected to the bottom of the sealing cylinder (11). A dissolved water and gas release head (16) is arranged at the bottom of the casing (15). The dissolved water and gas release head (16) is connected to the methane dissolution tank (3). The free end of the sludge circulation pipe (14) is arranged above the dissolved water and gas release head (16); 2. The wastewater denitrification device according to claim 1, characterized in that, A desulfurization microorganism packing (7) is arranged in the middle of the biological desulfurization filter (2). A water distributor and an air outlet pipe are arranged above the desulfurization microorganism packing (7). An air inlet pipe and a water outlet pipe are arranged below the desulfurization microorganism packing (7); 3. The wastewater denitrification device according to claim 2, characterized in that, The biological desulfurization filter (2) has two stages, including a primary desulfurization filter (8) and a secondary desulfurization filter (9). The air inlet pipe of the primary desulfurization filter (8) is connected to the anaerobic tower. The water distributor of the primary desulfurization filter (8) is connected to the biological aerated filter. The air outlet pipe of the primary desulfurization filter (8) is connected to the air inlet pipe of the secondary desulfurization filter (9). The water outlet pipe of the primary desulfurization filter (8) is connected to the anoxic tank; The water distributor of the secondary desulfurization filter (9) is connected to the clarifier (1). Two water outlet pipes are arranged at the bottom of the secondary desulfurization filter (9). The air outlet pipe and one of the water outlet pipes are connected to the methane dissolution tank (3) through a dissolved air pump (10). The other water outlet pipe is connected to the methane anaerobic denitrification bacteria packing area (5) in the methane anaerobic denitrification tank (4).

4. The wastewater denitrification device according to claim 1, characterized in that, Inside the methane anaerobic denitrification tank (4), there is a tube cylinder (17) with an open top, and the filtration device (6) is arranged inside the tube cylinder (17).

5. The wastewater denitrification device according to claim 3, wherein, The water outlet pipe of the primary desulfurization filter tank (8) is also communicated with the methane anaerobic denitrifying bacteria packing area (5) inside the methane anaerobic denitrification tank (4).

6. A method for nitrogen removal from wastewater, characterized in that, Using the denitrification device described in any one of claims 1-5 for denitrification treatment, specifically including the following steps: (1) Pass the nitrified muddy water mixture in the aerobic tank into the clarifier for muddy water separation to obtain clear liquid and sludge; (2) Simultaneously pass the clear liquid in step (1) and the biogas generated in the anaerobic tower into the biological desulfurization filter tank, use the desulfurizing microorganisms to remove hydrogen sulfide in the biogas and dissolved oxygen in the clear liquid, and at the same time reduce the pH of the clear liquid to facilitate anaerobic denitrification, and obtain the treated biogas and clear liquid; (3) Pass the biogas and part of the clear liquid obtained in step (2) into the methane dissolution tank through a dissolved air pump, dissolve methane in the clear liquid to prepare a supersaturated methane soda water mixture, and pass the remaining clear liquid generated by the biological desulfurization filter tank into the methane anaerobic denitrification tank; (4) Pass the supersaturated methane soda water mixture in step (3) into the methane anaerobic denitrification tank, and under the action of the methane anaerobic denitrifying bacteria in the methane anaerobic denitrifying bacteria packing area, achieve the purpose of denitrifying the clear liquid; (5) Filter the effluent after the denitrification treatment in step (4) through a filtration device, and then discharge it into the biological aerated filter to remove the remaining pollutants; the filtration device intercepts a large amount of sludge containing methane anaerobic denitrifying bacteria, and discharges the sludge into the sleeve in the pressurized area through the sludge circulation pipe, mixes it with the continuously introduced supersaturated methane soda water mixture to improve the anaerobic denitrification efficiency, and the pressurized muddy water mixture is released to the methane anaerobic denitrifying bacteria packing area through the sludge release pipe. A large number of methane bubbles are generated during the release process, further increasing the mass transfer efficiency of methane and improving the anaerobic denitrification treatment efficiency.

7. The wastewater denitrification method according to claim 6, wherein, In step (2), the dissolved oxygen in the clear liquid is controlled below 0.3 mg / L, and the pH of the clear liquid is reduced to 6.0-6.5; in step (3), methane is dissolved in the clear liquid under the high pressure of 0.5-0.6 Mpa.

8. The wastewater denitrification method according to claim 7, characterized in that, When the pH in the methane anaerobic denitrifying bacteria packing area is higher than 7.5, pump part of the acidic clear liquid of the biological desulfurization filter tank into the methane anaerobic denitrifying bacteria packing area to keep the pH in the methane anaerobic denitrification packing area at 6.0-6.5 to improve the anaerobic denitrification efficiency.

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