A wastewater treatment device and method based on carbon source recovery coupled with anaerobic ammonia oxidation

Abstract

The application relates to the field and provides a wastewater treatment device and method based on carbon source recovery coupled with anaerobic ammonia oxidation. The device comprises a biological flocculation tank, a vertical flow sedimentation tank, an anaerobic digestion tank, a Sharon tank, a two-stage A / O composite denitrification device and a secondary sedimentation tank. The denitrification method based on carbon source recovery coupled with anaerobic ammonia oxidation provided by the application has the advantages of low carbon source consumption, efficient denitrification of domestic sewage and recovery of biomass energy carbon source.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and more specifically, to a wastewater treatment device and method based on carbon source recovery coupled with anaerobic ammonia oxidation. Background Technology

[0002] Traditional wastewater treatment processes, such as A2 / O and oxidation ditches, are limited by their own principles and involve the destructive removal of carbon, nitrogen, and phosphorus pollutants from water. They suffer from high energy consumption, high carbon emissions, and low resource recovery, which contradicts the current demand for energy conservation and emission reduction.

[0003] The emergence of anammox technology has made carbon source recovery from urban wastewater a feasible technical route. Anammox is an autotrophic nitrogen removal process that, compared to traditional nitrification-denitrification processes, saves all carbon sources and approximately 60% of oxygen demand. Due to the slow growth of anammox bacteria, the amount of sludge produced is relatively small, only about 10% of that produced by traditional nitrification-denitrification, thus reducing sludge treatment costs. Based on its numerous advantages, anammox has been a research hotspot in the water treatment field since its discovery. However, the application of anammox technology in urban wastewater is limited by its low ammonia nitrogen concentration and low temperature. One of the main reasons for this is the unstable source of nitrite nitrogen, one of the substrates for anammox bacteria.

[0004] To address the issue of unstable nitrite nitrogen sources in urban wastewater treatment using anaerobic ammonia oxidation (ANAO) processes, there is an urgent need to develop a new denitrification method based on carbon source recovery coupled with ANAO. Summary of the Invention

[0005] The purpose of this invention is to provide a wastewater treatment device and method based on carbon source recovery coupled with anaerobic ammonia oxidation.

[0006] To achieve the objectives of this invention, in a first aspect, this invention provides a wastewater treatment device based on carbon source recovery coupled with anaerobic ammonia oxidation, comprising a biological flocculation tank, a vertical flow sedimentation tank, an anaerobic digestion tank, a Sharon tank, a two-stage A / O composite denitrification device, and a secondary sedimentation tank.

[0007] The biological flocculation tank is used to enrich the carbon source of non-dissolved organic matter in wastewater.

[0008] The vertical flow sedimentation tank is used to separate low-carbon, high-nitrogen water from concentrated sludge in the sludge mixture. The effluent from the vertical flow sedimentation tank enters a two-stage A / O composite denitrification device.

[0009] The two-stage A / O combined denitrification device consists of a primary anoxic tank, a secondary anoxic tank, and an aerobic tank connected in series. The tanks are separated by partitions with holes, or they are connected by pipes. Water flows from the primary anoxic tank to the secondary anoxic tank, and from the secondary anoxic tank to the aerobic tank. Agitators are installed above the primary and secondary anoxic tanks.

[0010] One sidewall of the biological flocculation tank is connected to the wastewater inlet pipe, and the other sidewall is connected to one sidewall of the vertical flow sedimentation tank through a first pipe. The bottom of the vertical flow sedimentation tank is connected to the anaerobic digestion tank through a second pipe. The other sidewall of the vertical flow sedimentation tank is connected to the first-stage anoxic tank of the two-stage A / O composite denitrification device through a third pipe. The top of the vertical flow sedimentation tank is also equipped with a mud-water separation agitator.

[0011] An exhaust pipe is provided on the upper side wall of one side of the anaerobic digester, and a sludge discharge pipe is provided at the bottom; the other side wall of the anaerobic digester is connected to the Sharon tank through a liquid outlet pipe I; a stirrer is also provided inside the anaerobic digester.

[0012] The Sharon pool is connected to the secondary anoxic pool in the two-stage A / O composite denitrification device via the outlet pipe II.

[0013] Water flowing out of the aerobic tank in the two-stage A / O composite denitrification device enters the secondary sedimentation tank through the effluent pipe III. The sludge is separated into mud and water through the deep treatment in the secondary sedimentation tank, and the discharged sludge enters the anaerobic digestion tank through the second pipeline.

[0014] The anaerobic digester is used to anaerobic digest sludge and produce biogas to recover carbon sources; the anaerobic digested sludge contains facultative anaerobic bacteria and obligate anaerobic bacteria.

[0015] The supernatant produced from the anaerobic digester enters the Sharon tank. After the ammonia nitrogen in the supernatant is converted into nitrite nitrogen by controlling the DO, it enters the secondary anoxic tank.

[0016] The Sharon tank is filled with polyethylene filler, with a filling rate of 10-40%.

[0017] The low-carbon, high-nitrogen water flowing out of the vertical flow sedimentation tank and the aerobic nitrified liquid flowing out of the aerobic tank are internally recirculated to the primary anoxic tank (where denitrifying bacteria grow naturally), and denitrification is carried out using the denitrifying bacteria in the primary anoxic tank.

[0018] Anaerobic ammonia oxidation occurs in the secondary anoxic tank (anaerobic ammonia oxidizing bacteria grow naturally).

[0019] In the aerobic tank, ammonia nitrogen is converted into nitrate nitrogen through a nitrification reaction.

[0020] Further, the filling rate of the packing material in the primary anoxic tank is 10-40%. The packing material, as described in CN201611250004.0, comprises the following components by weight: 94-97 parts high-density polyethylene, 2-4 parts calcium carbonate, 0.7-0.9 parts stearic acid or stearate, 0.3-0.5 parts carbonate, 0.08-0.12 parts polyhydroxy fatty amide, 0.08-0.12 parts trace elements, 0.08-0.12 parts biological enzymes, and 0.01-0.0 parts antioxidant. The composition includes 3 parts of ultraviolet absorber, 0.03-0.05 parts of ultraviolet absorber, and 0.02-0.04 parts of peroxide additive; wherein the trace elements are composed of trace elements from living organisms and trace elements from non-living organisms in a weight ratio of 1:5 to 1:2, the trace elements from living organisms are cobalt, the trace elements from non-living organisms are rare earth elements, the biological enzyme is alkaline protease, the antioxidant is p-phenylenediamine, the ultraviolet absorber is benzophenone, and the peroxide additive is di-tert-butyl peroxide.

[0021] The packing material in the secondary anoxic tank is the same as that in the primary anoxic tank, with a filling rate of 10-40%.

[0022] The aerobic tank is filled with polyethylene, with a filling rate of 10-40%.

[0023] Secondly, the present invention provides the application of the device in wastewater treatment (denitrification).

[0024] Thirdly, the present invention provides a wastewater treatment method based on carbon source recovery coupled with anaerobic ammonia oxidation, which utilizes the aforementioned device for wastewater denitrification, comprising the following steps: Step 1: The wastewater, after primary treatment to remove suspended solids through pretreatment systems such as screens, grit chambers, or equalization tanks, enters a biological flocculation tank to enrich the carbon source in the wastewater. Step 2: The sludge mixture obtained in Step 1 enters a vertical flow sedimentation tank to separate the low-carbon, high-nitrogen wastewater from the concentrated sludge; Step 3: Part of the settled sludge is returned to the biological flocculation tank through a second pipeline connected to the bottom of the vertical flow sedimentation tank, ensuring a certain sludge concentration in the settled sludge; the remaining sludge is sent to the anaerobic digestion tank for treatment through the second pipeline connected to the bottom of the vertical flow sedimentation tank. Step 4: The sludge that enters the anaerobic digester in Step 3 produces biogas through the anaerobic digestion process of the sludge, so as to realize the recovery of carbon source. Step 5: After the anaerobic digestion process in Step 4, the stirrer stops stirring, and the supernatant produced after settling and separation enters the Sharon tank. By controlling DO at 0.8~2.5 mg / L, the ammonia nitrogen in the supernatant is converted into nitrite nitrogen, and then enters the secondary anoxic tank to provide a stable source of nitrite nitrogen for the secondary anoxic tank, so as to realize the anaerobic ammonia oxidation reaction. Step 6: The low-carbon, high-nitrogen wastewater separated in Step 2 is treated by a two-stage anoxic A / O combined denitrification process; wherein, the aerobic nitrification liquid is internally refluxed to the first-stage anoxic tank, and together with the low-carbon, high-nitrogen wastewater (containing organic matter) entering the first-stage anoxic tank, denitrification is carried out in the first-stage anoxic tank. Step 7: The effluent from Step 6 enters the secondary anoxic tank and undergoes an anaerobic ammonia oxidation reaction, which further reduces the ammonia nitrogen concentration. Step 8: Following Step 7, the effluent from the secondary anoxic tank enters the aerobic tank, where nitrifying bacteria convert all the remaining ammonia nitrogen in the wastewater into nitrate nitrogen through a nitrification process. The remaining recalcitrant organic matter in the primary anoxic tank is further mineralized in the aerobic tank and converted into CO2, so that the COD concentration of the effluent meets the standard. At the same time, the effluent from the aerobic tank enters the secondary sedimentation tank through the effluent pipe. Step 9: The effluent entering the secondary sedimentation tank undergoes deep treatment to separate the mud and water, further removing suspended solids from the water; at the same time, the detached and aged biofilm is further collected and, together with the remaining sludge from the biological flocculation tank, enters the anaerobic digester through the second pipeline.

[0025] Furthermore, the specific processing conditions are as follows: The HRT (Heat Retention Time) of the biological flocculation tank is 20 min to 2 h (preferably 30 min), and the flow rate is no higher than 20,000 m³ / h. 3 / d, water temperature not lower than 10℃, pH 6~9.

[0026] The two-stage A / O combined denitrification unit adopts the MBBR process, with an HRT of 8~20 h, of which the HRT of the first-stage anoxic tank is 2~4 h, the HRT of the second-stage anoxic tank is 2~4 h, and the HRT of the aerobic tank is 4~12 h. The temperature of the primary anoxic tank, the secondary anoxic tank, and the aerobic tank should not be lower than 10℃, and the pH should be 6~9.

[0027] By employing the above technical solution, the present invention has at least the following advantages and beneficial effects: (i) This invention recovers carbon sources from urban sewage to produce methane.

[0028] (ii) Introduce autotrophic denitrification technology, combine autotrophic denitrification with heterotrophic denitrification, and improve denitrification efficiency.

[0029] (iii) By recovering the carbon source of biomass energy, the dependence on additional carbon sources during the treatment process is reduced, achieving low carbon source consumption and reducing operating costs.

[0030] (iv) The use of multiple treatment units, such as biological flocculation tank, vertical flow sedimentation tank, anaerobic digestion tank, Sharon tank, two-stage A / O composite denitrification device and secondary sedimentation tank, ensures the stability of treatment effect. Attached Figure Description

[0031] Figure 1 This is a flow chart of the denitrification process based on carbon source recovery coupled with anaerobic ammonia oxidation, as described in this invention. 100 - Biological flocculation tank, 110 - First pipeline, 200 - Vertical flow sedimentation tank, 210 - Third pipeline, 220 - Second pipeline, 230 - Sludge-water separation stirrer, 300 - Two-stage anoxic A / O composite denitrification process unit, 310 - Primary anoxic tank, 320 - Secondary anoxic tank, 330 - Aerobic tank, 340 - Effluent pipe III, 350 - Nitrified liquid return pipe, 400 - Secondary sedimentation tank, 410 - Sludge-water separation stirrer, 500 - Anaerobic digester, 510 - Exhaust pipe, 520 - Stirrer, 530 - Stirrer, 540 - Effluent pipe I, 600 - Sharon tank, 610 - Effluent pipe II. Detailed Implementation

[0032] Addressing existing bottlenecks in anaerobic ammonia oxidation (ANAO) processes: low temperatures leading to low activity of ANAO bacteria and unstable effluent quality; high carbon-to-nitrogen ratios resulting in competition for living space and substrate by heterotrophic bacteria; and low ammonia nitrogen concentrations hindering effective nitrification. This invention provides a denitrification method based on carbon source recovery coupled with ANAO. By combining autotrophic and heterotrophic denitrification, it addresses the issue of unstable nitrite sources by utilizing the high-ammonia-nitrogen-concentration anaerobic digestion supernatant for nitrification, generating nitrite nitrogen to provide a stable and reliable nitrite nitrogen source for ANAO bacteria in the anoxic tank. Simultaneously, an MBBR system is used in a staged manner, allowing heterotrophic denitrifying bacteria and autotrophic denitrifying bacteria to grow on different substrates, thereby influencing the growth of ANAO bacteria and addressing the problem of slow growth due to high carbon-to-nitrogen ratios.

[0033] The present invention adopts the following technical solution: This invention provides a denitrification method based on carbon source recovery coupled with anaerobic ammonia oxidation, including a biological flocculation tank 100, a vertical flow sedimentation tank 200, a two-stage anoxic A / O composite denitrification process unit 300, a primary anoxic tank 310, a secondary anoxic tank 320, an aerobic tank 330, a secondary sedimentation tank 400, an anaerobic digestion tank 500, and a Sharon tank 600.

[0034] The bioflocculation tank 100 and the vertical flow sedimentation tank 200 constitute a biological adsorption unit. The bioflocculation tank 100 is used to enrich the carbon source of non-dissolved organic matter in the wastewater. One side wall of the bioflocculation tank 100 is connected to the outlet of the inlet pipe; wastewater enters the bioflocculation tank through the inlet pipe.

[0035] The vertical flow sedimentation tank 200 is used to separate low-carbon, high-nitrogen wastewater from concentrated sludge in the sludge mixture. The vertical flow sedimentation tank 200 is connected to the biological flocculation tank 100 via a first pipeline 110. The sedimentation tank 200 is connected to the anaerobic digester 500 via a second pipeline 220.

[0036] Furthermore, the vertical flow sedimentation tank 200 is also connected to the two-stage anoxic A / O composite denitrification process unit 300, which consists of a primary anoxic tank 310, a secondary anoxic tank 320, and an aerobic tank 330, via a third pipeline 210.

[0037] In the two-stage anoxic A / O combined denitrification process unit 300, the first-stage anoxic tank utilizes the remaining carbon source for denitrification, consuming the carbon source. The second-stage anoxic tank contains anaerobic ammonia oxidation biofilm suspended packing, which can utilize ammonia nitrogen and nitrite nitrogen in the water for anaerobic ammonia oxidation.

[0038] Furthermore, the filling rate of the anaerobic ammonia-oxidizing bacteria biofilm packing material in the secondary anoxic tank is 10-30%.

[0039] This invention provides a denitrification method based on carbon source recovery coupled with anaerobic ammonia oxidation, comprising the following steps: Step 1: After primary treatment, the wastewater, which has been pretreated by a screen, grit chamber or equalization tank to remove suspended solids, enters the biological flocculation tank 100. The activated sludge is used to rapidly and efficiently enrich the carbon source in the influent with non-dissolved organic matter in the wastewater and make resource utilization.

[0040] Step 2: The sludge mixture obtained in Step 1 enters the vertical flow sedimentation tank 200 to separate the low-carbon, high-nitrogen wastewater from the concentrated sludge (the sedimentation tank has a mud-water separation agitator 230 at the top); the low-carbon, high-nitrogen wastewater enters the subsequent two-stage anoxic A / O composite denitrification process unit 300 through the liquid outlet pipe 210 (third pipeline) on the side surface of the vertical flow sedimentation tank.

[0041] Step 3: Part of the settled sludge is returned to the biological flocculation tank 100 through the bottom outlet pipe 220 (second pipeline) to ensure a certain sludge concentration in the settled sludge; the remaining sludge is controlled to enter the anaerobic digester 500 for treatment through the bottom outlet pipe 220 (second pipeline).

[0042] Step 4: In step 3, the organic matter in the sludge entering the anaerobic digester 500 is decomposed and converted into biogas by facultative anaerobic bacteria and obligate anaerobic bacteria through the anaerobic digestion process of the sludge under anaerobic conditions. The biogas produced is discharged through the exhaust pipe (exhaust pipe) 510 above the side surface of the anaerobic digester, thereby realizing the recovery of carbon source.

[0043] Step 5: After the anaerobic digestion process in Step 4, stirrers 520 and 530 stop stirring. The supernatant produced after settling and separation enters the Sharon tank 600 through the effluent outlet 540 (outlet pipe I) on the side surface for ammonia nitrogen conversion. The ammonia nitrogen is converted to nitrite nitrogen by controlling the dissolved oxygen (DO). At the same time, it is pumped into the secondary anoxic tank through the effluent outlet 610 (outlet pipe II) on the side surface of the Sharon tank, providing a stable source of nitrite nitrogen for the secondary anoxic tank of the two-stage anoxic A / O combined denitrification process, thus satisfying the anaerobic ammonia oxidation reaction.

[0044] Step 6: The effluent from Step 2, which enters the two-stage anoxic A / O combined denitrification process unit 300, undergoes further treatment. The aerobic nitrified liquor is internally recirculated to the primary anoxic tank 310. The primary anoxic tank 310 receives the effluent (containing organic matter) from the sedimentation tank 200 and the internally recirculated aerobic nitrified liquor. In the primary anoxic tank 310, the nitrate nitrogen reacts with the nitrogen in the recirculated liquor, undergoing denitrification. The nitrified liquor return pipe 350 is used to return the nitrified liquor from the aerobic tank to the primary anoxic tank for denitrification.

[0045] Step 7: The effluent from Step 6 enters the secondary anoxic tank 320 and undergoes an anaerobic ammonia oxidation reaction. The ammonia nitrogen concentration in the secondary anoxic tank 320 is further reduced, and there is almost no usable organic matter.

[0046] Step 8: The effluent from Step 7 enters the aerobic tank 330. Nitrifying bacteria convert all the remaining ammonia nitrogen in the wastewater into nitrate nitrogen through the nitrification process. The remaining recalcitrant organic matter in the primary anoxic tank 310 is further mineralized in the aerobic tank 330 and converted into CO2, so that the COD concentration of the effluent meets the standard. At the same time, the effluent from the aerobic tank 330 enters the secondary sedimentation tank 400 through the side surface liquid outlet pipe 340 (liquid outlet pipe III).

[0047] Step 9: The effluent from Step 8 enters the secondary sedimentation tank 400 for deep treatment to separate the sludge and water (the secondary sedimentation tank has a sludge-water separation agitator 410 at the top) to further remove suspended solids in the water; at the same time, the detached and aged biofilm is further collected and connected to the anaerobic digester 500 through the main sludge discharge pipe 220 together with the remaining sludge from the biological flocculation tank 100.

[0048] The process flow diagram of the denitrification process based on carbon source recovery coupled with anaerobic ammonium oxidation in this invention is shown below. Figure 1 .

[0049] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art, and the raw materials used are all commercially available products.

[0050] Example 1: Wastewater treatment device and method based on carbon source recovery coupled with anaerobic ammonium oxidation

[0051] Step 1: After primary treatment, the wastewater, which has been pretreated by a screen, grit chamber or equalization tank to remove suspended solids, enters the biological flocculation tank 100. The activated sludge is used to rapidly and efficiently enrich the carbon source in the influent with non-dissolved organic matter in the wastewater and make resource utilization.

[0052] Step 2: The sludge mixture obtained in Step 1 enters the vertical flow sedimentation tank 200 to separate the low-carbon, high-nitrogen wastewater from the concentrated sludge (the sedimentation tank has a mud-water separation agitator 230 at the top); the low-carbon, high-nitrogen wastewater enters the subsequent two-stage anoxic A / O composite denitrification process unit 300 through the liquid outlet pipe 210 (third pipeline) on the side surface of the vertical flow sedimentation tank.

[0053] Step 3: Part of the settled sludge is returned to the biological flocculation tank 100 through the bottom outlet pipe 220 (second pipeline) to ensure a certain sludge concentration in the settled sludge; the remaining sludge is controlled to enter the anaerobic digester 500 for treatment through the bottom outlet pipe 220 (second pipeline).

[0054] Step 4: In step 3, the organic matter in the sludge entering the anaerobic digester 500 is decomposed and converted into biogas by facultative anaerobic bacteria and obligate anaerobic bacteria through the anaerobic digestion process of the sludge under anaerobic conditions. The biogas produced is discharged through the exhaust pipe (exhaust pipe) 510 above the side surface of the anaerobic digester, thereby realizing the recovery of carbon source.

[0055] Step 5: After the anaerobic digestion process in Step 4, stirrers 520 and 530 stop stirring. The supernatant produced after settling and separation enters the Sharon tank 600 through the effluent outlet 540 (outlet pipe I) on the side surface for ammonia nitrogen conversion. The ammonia nitrogen is converted to nitrite nitrogen by controlling the dissolved oxygen (DO). At the same time, it is pumped into the secondary anoxic tank through the effluent outlet 610 (outlet pipe II) on the side surface of the Sharon tank, providing a stable source of nitrite nitrogen for the secondary anoxic tank of the two-stage anoxic A / O combined denitrification process, thus satisfying the anaerobic ammonia oxidation reaction.

[0056] Step 6: The effluent from Step 2, which enters the two-stage anoxic A / O combined denitrification process unit 300, undergoes further treatment. The aerobic nitrified liquor is internally recirculated to the primary anoxic tank 310. The primary anoxic tank 310 receives the effluent (containing organic matter) from the sedimentation tank 200 and the internally recirculated aerobic nitrified liquor. In the primary anoxic tank 310, the nitrate nitrogen reacts with the nitrogen in the recirculated liquor, undergoing denitrification. The nitrified liquor return pipe 350 is used to return the nitrified liquor from the aerobic tank to the primary anoxic tank for denitrification.

[0057] Step 7: The effluent from Step 6 enters the secondary anoxic tank 320 and undergoes an anaerobic ammonia oxidation reaction. The ammonia nitrogen concentration in the secondary anoxic tank 320 is further reduced, and there is almost no usable organic matter.

[0058] Step 8: The effluent from Step 7 enters the aerobic tank 330. Nitrifying bacteria convert all the remaining ammonia nitrogen in the wastewater into nitrate nitrogen through the nitrification process. The remaining recalcitrant organic matter in the primary anoxic tank 310 is further mineralized in the aerobic tank 330 and converted into CO2, so that the COD concentration of the effluent meets the standard. At the same time, the effluent from the aerobic tank 330 enters the secondary sedimentation tank 400 through the side surface liquid outlet pipe 340 (liquid outlet pipe III).

[0059] Step 9: The effluent from Step 8 enters the secondary sedimentation tank 400 for deep treatment to separate the sludge and water (the secondary sedimentation tank has a sludge-water separation agitator 410 at the top) to further remove suspended solids in the water; at the same time, the detached and aged biofilm is further collected and connected to the anaerobic digester 500 through the main sludge discharge pipe 220 together with the remaining sludge from the biological flocculation tank 100.

[0060] Repeat step 4. The denitrification device process based on carbon source recovery coupled with anaerobic ammonia oxidation provided by the present invention forms a closed loop cycle, which can not only convert wastewater into clean water that can meet the discharge standards, but also convert some of the carbon source in the wastewater into energy, thereby achieving the purpose of carbon source recovery.

[0061] Furthermore, the Sharon tank is filled with suspended packing material (polyethylene material), with a filling rate of 30%.

[0062] The packing materials in the primary and secondary anoxic tanks can be found in Example 1 of the instruction manual CN201611250004.0, with a filling rate of 20%.

[0063] In the primary anoxic tank, denitrifying bacteria grow naturally, while in the secondary anoxic tank, anaerobic ammonia-oxidizing bacteria grow naturally.

[0064] The packing material of the aerobic tank is made of polyethylene, with a filling rate of 20%.

[0065] It should be noted that the two-stage anoxic A / O combined denitrification process unit 300 simultaneously employs the MBBR process, resulting in significant differences in the microbial community structure of the suspended carrier biofilm in different tanks. For example, the biofilm in the first-stage anoxic tank 310 is dominated by heterotrophic denitrifying bacteria, while the biofilm in the second-stage anoxic tank 320 is enriched with anaerobic ammonia-oxidizing bacteria, and the biofilm in the aerobic tank 330 is enriched with a large number of nitrifying bacteria. This staged approach ensures that heterotrophic denitrifying bacteria and autotrophic denitrifying bacteria grow on different substrates, ultimately supporting the growth of anaerobic ammonia-oxidizing bacteria. The final ammonia nitrogen removal rate is >90%, TN removal rate is >70%, and COD removal rate is >80%.

[0066] Furthermore, the specific processing conditions are as follows: The HRT (Heat Retention Time) of the biological flocculation tank is 30 minutes, and the flow rate is no more than 20,000 m³ / min. 3 / day, water temperature not lower than 10℃, pH around 7.2.

[0067] The two-stage A / O combined denitrification unit adopts the MBBR process with a HRT of 11 h, of which the HRT of the first-stage anoxic tank is 3 h, the HRT of the second-stage anoxic tank is 3 h, and the HRT of the aerobic tank is 5 h; the temperature of the first-stage anoxic tank, the second-stage anoxic tank, and the aerobic tank is not lower than 10℃, and the pH is 7.2~7.5.

[0068] In summary, this invention provides a denitrification method based on carbon source recovery coupled with anaerobic ammonia oxidation, mainly addressing the technical problem that the denitrification effect of anaerobic ammonia oxidation technology in urban wastewater treatment is poor due to the unstable source of nitrite nitrogen in anoxic ponds. The denitrification method based on carbon source recovery coupled with anaerobic ammonia oxidation includes: a biological adsorption unit, comprising a biological flocculation tank and a secondary sedimentation tank; an inlet connected to the side surface of the biological flocculation tank; a sludge-water separation agitator at the top of the secondary sedimentation tank, which is connected to the biological flocculation tank, an anaerobic digestion tank, and a primary anoxic tank; and an anaerobic digestion tank, connected to the inlets at the bottom of the secondary and secondary sedimentation tanks, with a Sharon tank connected to its side surface, a gas exhaust pipe connected above the side surface, and a sludge outlet pipe connected to the biological flocculation tank at the bottom, while an agitator is connected from the top surface. The invention comprises a two-stage A / O composite denitrification unit, comprising a primary anoxic tank, a secondary anoxic tank, and an aerobic tank, and a secondary sedimentation tank. Aeration pipes are inserted above the primary and secondary anoxic tanks. The side surfaces of the two-stage A / O composite denitrification units are connected to the intermediate sedimentation tank and the secondary sedimentation tank, respectively. The bottom inlet of the secondary anoxic tank is connected to a Sharon tank. The top of the secondary sedimentation tank has a mud-water separation agitator, and the bottom drain pipe is connected to the anaerobic digester. The Sharon tank is connected to both the anaerobic digester and the secondary anoxic tank. This invention provides a denitrification method based on carbon source recovery coupled with anaerobic ammonia oxidation, achieving the advantages of efficient denitrification of domestic sewage with low carbon source consumption and recovery of biomass energy carbon sources.

[0069] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A wastewater treatment device based on carbon source recovery coupled with anaerobic ammonia oxidation, characterized in that, It includes a biological flocculation tank, a vertical flow sedimentation tank, an anaerobic digester, a Sharon tank, a two-stage A / O combined denitrification device, and a secondary sedimentation tank; The bio-flocculation tank is used to enrich the carbon source of non-dissolved organic matter in wastewater; The vertical flow sedimentation tank is used to separate low-carbon, high-nitrogen water from concentrated sludge in sludge mixture. The effluent from the vertical flow sedimentation tank enters a two-stage A / O composite denitrification device. The two-stage A / O composite denitrification device consists of a primary anoxic tank, a secondary anoxic tank, and an aerobic tank connected in series. Each tank is separated by a partition with holes, or the tanks are connected by pipes. Along the water flow direction, water from the primary anoxic tank flows into the secondary anoxic tank, and water from the secondary anoxic tank flows into the aerobic tank. A stirrer is installed above the primary and secondary anoxic tanks. One sidewall of the biological flocculation tank is connected to the wastewater inlet pipe, and the other sidewall is connected to one sidewall of the vertical flow sedimentation tank through a first pipe. The bottom of the vertical flow sedimentation tank is connected to the anaerobic digestion tank through a second pipe, and the other sidewall of the vertical flow sedimentation tank is connected to the first-stage anoxic tank of the two-stage A / O composite denitrification device through a third pipe. The top of the vertical flow sedimentation tank is also equipped with a mud-water separation agitator. An exhaust pipe is provided on the upper part of one side wall of the anaerobic digester, and a sludge discharge pipe is provided at the bottom; the other side wall of the anaerobic digester is connected to the Sharon tank through a liquid outlet pipe I; a stirrer is also provided inside the anaerobic digester. The Sharon pool is connected to the secondary anoxic pool in the two-stage A / O composite denitrification device via the liquid outlet pipe II. Water flowing out of the aerobic tank in the two-stage A / O composite denitrification device enters the secondary sedimentation tank through the effluent pipe III. The sludge is separated into mud and water through the deep treatment in the secondary sedimentation tank, and the discharged sludge enters the anaerobic digestion tank through the second pipeline. The supernatant produced from the anaerobic digester enters the Sharon tank. After the ammonia nitrogen in the supernatant is converted into nitrite nitrogen by controlling the DO, it enters the secondary anoxic tank. Anaerobic ammonia oxidation reaction occurs in the secondary anoxic tank.

2. The apparatus according to claim 1, characterized in that, The sludge undergoes anaerobic digestion in the anaerobic digester, producing biogas to achieve carbon source recovery. Anaerobic digestion sludge contains both facultative anaerobic bacteria and obligate anaerobic bacteria.

3. The apparatus according to claim 2, characterized in that, The Sharon tank is filled with polyethylene filler, with a filling rate of 10-40%.

4. The apparatus according to claim 1, characterized in that, The low-carbon, high-nitrogen water flowing out of the vertical flow sedimentation tank and the aerobic nitrified liquid flowing out of the aerobic tank are internally recirculated to the first-stage anoxic tank, where denitrification is carried out by denitrifying bacteria in the first-stage anoxic tank. In the aerobic tank, ammonia nitrogen is converted into nitrate nitrogen through a nitrification reaction; The filling rate of the packing material in the primary anoxic tank is 10-40%, and the packing material comprises the following components in parts by weight: 94-97 parts high-density polyethylene, 2-4 parts calcium carbonate, 0.7-0.9 parts stearic acid or stearate, 0.3-0.5 parts carbonate, 0.08-0.12 parts polyhydroxy fatty amide, 0.08-0.12 parts trace elements, 0.08-0.12 parts biological enzymes, 0.01-0.03 parts antioxidant, and 0.0 parts ultraviolet absorber. 3 to 0.05 parts and peroxide additive 0.02 to 0.04 parts; wherein, the trace elements are composed of trace elements in organisms and trace elements in abiotic substances in a weight ratio of 1:5 to 1:2, the trace elements in organisms are cobalt, the trace elements in abiotic substances are rare earth elements, the biological enzyme is alkaline protease, the antioxidant is p-phenylenediamine, the ultraviolet absorber is benzophenone, and the peroxide additive is di-tert-butyl peroxide; The packing material in the secondary anoxic tank is the same as that in the primary anoxic tank, with a filling rate of 10-40%. The aerobic tank is filled with polyethylene, with a filling rate of 10-40%.

5. The application of the apparatus according to any one of claims 1-4 in wastewater treatment.

6. A wastewater treatment method based on carbon source recovery coupled with anaerobic ammonia oxidation, characterized in that, Wastewater denitrification using the apparatus according to any one of claims 1-4 includes the following steps: Step 1: Wastewater that has undergone primary treatment, including the removal of suspended solids by a screen, grit chamber, or equalization tank, enters a biological flocculation tank to enrich the carbon source in the wastewater. Step 2: The sludge mixture obtained in Step 1 enters a vertical flow sedimentation tank to separate the low-carbon, high-nitrogen wastewater from the concentrated sludge; Step 3: Part of the settled sludge is returned to the biological flocculation tank through a second pipeline connected to the bottom of the vertical flow sedimentation tank, so as to ensure that the settled sludge has a certain concentration. Some of the remaining sludge enters the anaerobic digester for treatment through a second pipeline connected to the bottom of the vertical flow sedimentation tank. Step 4: The sludge that enters the anaerobic digester in Step 3 produces biogas through the anaerobic digestion process of the sludge, so as to realize the recovery of carbon source. Step 5: After the anaerobic digestion process in Step 4, the stirrer stops stirring, and the supernatant produced after settling and separation enters the Sharon tank. By controlling DO at 0.8~2.5 mg / L, the ammonia nitrogen in the supernatant is converted into nitrite nitrogen, and then enters the secondary anoxic tank to provide a stable source of nitrite nitrogen for the secondary anoxic tank, so as to realize the anaerobic ammonia oxidation reaction. Step 6: The low-carbon, high-nitrogen wastewater separated in Step 2 is treated by a two-stage anoxic A / O combined denitrification process; wherein, the aerobic nitrification liquid is internally refluxed to the first-stage anoxic tank, and together with the low-carbon, high-nitrogen wastewater entering the first-stage anoxic tank, denitrification is carried out in the first-stage anoxic tank. Step 7: The effluent from Step 6 enters the secondary anoxic tank and undergoes an anaerobic ammonia oxidation reaction, which further reduces the ammonia nitrogen concentration. Step 8: Following Step 7, the effluent from the secondary anoxic tank enters the aerobic tank, where nitrifying bacteria convert all the remaining ammonia nitrogen in the wastewater into nitrate nitrogen through a nitrification process. The remaining recalcitrant organic matter in the primary anoxic tank is further mineralized in the aerobic tank and converted into CO2, so that the COD concentration of the effluent meets the standard. At the same time, the effluent from the aerobic tank enters the secondary sedimentation tank through the effluent pipe. Step 9: The effluent entering the secondary sedimentation tank undergoes deep treatment to separate the mud and water, further removing suspended solids from the water; at the same time, the detached and aged biofilm is further collected and, together with the remaining sludge from the biological flocculation tank, enters the anaerobic digester through the second pipeline.

7. The method according to claim 6, characterized in that, The specific processing conditions are as follows: The HRT of the biological flocculation tank is 20 min to 2 h, and the flow rate is no more than 20,000 m³. 3 / d, water temperature not lower than 10℃, pH 6~9; The two-stage A / O combined denitrification unit adopts the MBBR process, with an HRT of 8~20 h, of which the HRT of the first-stage anoxic tank is 2~4 h, the HRT of the second-stage anoxic tank is 2~4 h, and the HRT of the aerobic tank is 4~12 h. The temperature of the primary anoxic tank, the secondary anoxic tank, and the aerobic tank should not be lower than 10℃, and the pH should be 6~9.

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