Biological denitrification method for water body

Abstract

The invention belongs to the technical field of water treatment, and relates to a biological denitrification method for a water body, which comprises the following steps: adding microorganisms into raw water in an anaerobic environment, starting the biological denitrification method for the water body, and carrying out an oxidation-reduction reaction to obtain denitrified water, the microorganisms are ammoxidation archaea, ammoxidation bacteria and anaerobic ammonium oxidation bacteria; wherein the concentration of ammonia nitrogen in the raw water is 40 mg / L-60 mg / L; the addition amount of the ammonia-oxidizing archaea is 5 * 10 < 6 > copies / gVSS to 8 * 10 < 6 > copies / gVSS; the addition amount of the ammonia oxidizing bacteria is 2 * 10 < 6 > copies / gVSS and 6 * 10 < 6 > copies / gVSS; the addition amount of the anaerobic ammonium oxidation bacteria is 0.5 * 10 < 6 > copies / gVSS to 2.0 * 10 < 6 > copies / gVSS, and oxygen required by AOB ammoxidation is provided by AOA, so that no aeration device is needed for oxygen supply.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and particularly relates to a method for biological nitrogen removal from water bodies. Background Art

[0002] The anaerobic ammonium oxidation (anammox) biological nitrogen removal process has advantages such as no need for carbon source, low sludge production, and saving 60% of the aeration volume compared to the traditional nitrification-denitrification biological nitrogen removal process, and is known as a low-carbon and highly efficient biological nitrogen removal process in the 21st century. However, the nitrite nitrogen required by the anammox process still needs to be produced by AOB (Ammonia oxidizing bacteria) oxidizing ammonia nitrogen using oxygen. Since aeration accounts for 60% of the operating cost of municipal wastewater treatment plants, this means that only aeration in the anammox process still accounts for about 24% of the municipal wastewater treatment cost. Therefore, how to further reduce the aeration volume and save the nitrogen removal treatment cost has become a difficult problem that urgently needs to be solved in the sewage biological nitrogen removal process, especially the anammox process. Summary of the Invention

[0003] To solve the above problems, the present invention provides a method for biological nitrogen removal from water bodies.

[0004] A method for biological nitrogen removal from water bodies, adding microorganisms to raw water in an anaerobic environment to carry out an oxidation-reduction reaction to obtain nitrogen-removed water; The microorganisms are ammonia-oxidizing archaea, ammonia-oxidizing bacteria, and anaerobic ammonium-oxidizing bacteria; Among them, the ammonia nitrogen concentration in the raw water is 40 mg / L to 60 mg / L; The addition amount of the ammonia-oxidizing archaea is 5×10 6 copies / gVSS to 8×10 6 copies / gVSS; The addition amount of the ammonia-oxidizing bacteria is 2×10 6 copies / gVSS to 6×10 6 copies / gVSS; The addition amount of the anaerobic ammonium-oxidizing bacteria is 0.5×10 6 copies / gVSS to 2.0×10 6 copies / gVSS.

[0005] Preferably, the temperature of the anaerobic environment is 30°C to 35°C.

[0006] Preferably, the dissolved oxygen concentration in the anaerobic environment is ≤10 μg / L.

[0007] Preferably, the pH of the raw water is 7.8 to 8.2.

[0008] Preferably, the start-up method includes the following steps: AOA and AnAOB adaptation stage: Inoculate the sludge containing AnAOB microorganisms, the sludge containing AOA microorganisms, and the sludge containing AOB microorganisms into an anaerobic environment, and inoculate the raw water into the anaerobic environment; wherein, the ammonia nitrogen in the raw water is 200 mg / L, the concentration of nitrite nitrogen in the raw water gradually decreases from 264 mg / L to 100 mg / L, and the alkalinity concentration of the raw water is 600 mg / L - 800 mg / L; Start-up stage: The ammonia nitrogen concentration in the raw water gradually decreases from 200 mg / L to 50 mg / L, the concentration of nitrite nitrogen in the raw water is 0 mg / L, and the alkalinity concentration of the raw water is 600 mg / L - 800 mg / L.

[0009] Preferably, the water inlet mode is continuous water inlet.

[0010] Preferably, during the process of gradually decreasing the nitrite nitrogen concentration, when the total nitrogen removal rate reaches 60% at the previous nitrite nitrogen concentration, the nitrite nitrogen concentration is decreased.

[0011] Preferably, each nitrite nitrogen concentration section operates for 14 to 17 days.

[0012] Preferably, during the process of gradually decreasing the ammonia nitrogen concentration, when the total nitrogen removal rate reaches 40% at the previous ammonia nitrogen concentration, the ammonia nitrogen concentration is decreased.

[0013] Preferably, each ammonia nitrogen concentration operates for 14 to 17 days.

[0014] A rapid start-up method for a novel biological nitrogen removal method coupling ammonia-oxidizing archaea with anaerobic ammonia oxidation has the following steps in a typical upflow anaerobic sludge bed device: Step 1, Stage I: AOA and AnAOB adaptation stage: Inoculate AnAOB sludge (volume 1 L - 1.5 L, MLSS (mixed liquor suspended solids concentration) 3500 mg / L - 4000 mg / L), anaerobic sludge from a municipal wastewater treatment plant (volume 1 L - 1.5 L, MLSS 3000 mg / L - 4500 mg / L) and aerobic sludge from a municipal wastewater treatment plant (volume 1 L - 1.5 L, MLSS 2000 mg / L - 3000 mg / L) into the reactor and mix them evenly. Control the influent ammonia nitrogen concentration at 200 mg / L, and gradually reduce the influent nitrite nitrogen concentration from 264 mg / L to 100 mg / L (concentrations are 264 mg / L, 200 mg / L, 150 mg / L, 100 mg / L respectively). The hydraulic retention time HRT is 24 h, the influent alkalinity concentration is 600 mg / L - 800 mg / L, the reactor temperature is 30°C - 35°C. Control the reactor to be sealed in an anaerobic environment, the influent mode is continuous influent, and the influent substrate uses nitrogen aeration to control the dissolved oxygen concentration below 10 μg / L. The influent pH is 7.8 - 8.2; each small stage operates for 14 - 17 days. When the total nitrogen removal rate of the reactor reaches 60%, proceed to the next stage of operation.

[0015] AOA produces oxygen under anaerobic conditions. The AOB in the reactor quickly uses the oxygen produced by AOA to oxidize about 60% of the ammonia nitrogen to generate nitrite nitrogen and maintains the anaerobic environment unchanged. The AnAOB in the reactor uses part of the nitrite nitrogen oxidized by AOB and the remaining ammonia nitrogen to generate nitrate nitrogen and nitrogen gas, realizing low-carbon and high-efficiency ammonia removal treatment under fully anaerobic conditions.

[0016] Step 2, Stage II: AOA-coupled anaerobic ammonia oxidation novel biological nitrogen removal method startup stage: Control the influent nitrite concentration at 0, and gradually reduce the influent ammonia nitrogen concentration from 200 mg / L to 50 mg / L (concentrations are 200 mg / L, 150 mg / L, 100 mg / L, 50 mg / L respectively). The hydraulic retention time HRT is 24 h, the influent alkalinity concentration is 600 mg / L - 800 mg / L, the reactor temperature is 30°C - 35°C. Control the reactor to be sealed in an anaerobic environment, the influent mode is continuous influent, and the influent substrate uses nitrogen aeration to control the dissolved oxygen concentration below 10 μg / L. Each small stage operates for 14 - 17 days. When the total nitrogen removal rate of the reactor reaches 40%, proceed to the next stage of operation.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: In the method for biological nitrogen removal from water bodies of the present invention, the oxygen generated by AOA is utilized by ammonia-oxidizing bacteria for ammonia oxidation. Meanwhile, anaerobic ammonia-oxidizing bacteria convert the remaining ammonia nitrogen and the generated nitrite nitrogen into nitrogen gas and nitrate nitrogen, achieving low-carbon and high-efficiency nitrogen removal from municipal sewage. Compared with the anammox biological nitrogen removal method that requires AOB to provide oxygen through aeration, in the present invention, the oxygen required for AOB ammonia oxidation is provided by AOA. Therefore, no aeration device is needed for oxygen supply, and the sewage treatment cost can be reduced by about 24%.

[0018] Aiming at the characteristics of low ammonia nitrogen concentration in the water quality of AOA in the ocean, municipal sewage treatment plants and municipal water treatment plants, the applicable object of the present invention is municipal sewage with low ammonia nitrogen concentration, and a rapid start-up method for a new biological nitrogen removal method coupling ammonia-oxidizing archaea and anaerobic ammonia oxidation suitable for the water quality characteristics of low ammonia nitrogen sewage has been developed. Brief Description of the Drawings

[0019] Figure 1 It is the schematic diagram of the nitrogen removal method of the present invention.

[0020] Figure 2 It is the influent and effluent concentrations of ammonia nitrogen, nitrite nitrogen, nitrate nitrogen and the total nitrogen removal effect diagram of the start-up method of the nitrogen removal method of the present invention.

[0021] Figure 3 It is the gene quantity change diagram of the functional microorganisms AOA, AOB and AnAOB of the nitrogen removal method of the present invention. Detailed Embodiments

[0022] The following describes the detailed embodiments of the present invention in detail, but it should be understood that the protection scope of the present invention is not limited by the detailed embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0023] The applicable object of the present invention is municipal sewage with low ammonia nitrogen concentration, and the specific ammonia nitrogen concentration is 40 mg / L to 60 mg / L.

[0024] The Chinese name of VSS in the present invention is volatile suspended solids, which appears in the text in the unit copies / gVSS. Taking 0.73×10 6 copies / gVSS as an example to illustrate the meaning of the unit: the amount of bacteria contained in each gram of volatile suspended solids is 0.73×10 6 copies.

[0025] Example 1 A method for coupling ammonia-oxidizing archaea and anaerobic ammonia oxidation for nitrogen removal, comprising the following steps: The raw water is treated in an anaerobic environment. Ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), and anaerobic ammonia-oxidizing bacteria (AnAOB) are added to the raw water. After startup, a redox reaction occurs to obtain the water with nitrogen removed. Among them, the quantities of AOA, AOB, and AnAOB are 5×10 6 copies / gVSS to 8×10 6 copies / gVSS, 2×10 6 copies / gVSS to 6×10 6 copies / gVSS, 0.5×10 6 copies / gVSS to 2.0×10 6 copies / gVSS respectively.

[0026] In the present invention, the process of the redox reaction is as follows: The oxygen generated by AOA is utilized by ammonia-oxidizing bacteria for ammonia oxidation. Meanwhile, anaerobic ammonia-oxidizing bacteria convert the remaining ammonia nitrogen and the generated nitrite nitrogen into nitrogen gas and nitrate nitrogen, achieving low-carbon and high-efficiency nitrogen removal from municipal sewage. Specifically as follows: AOA oxygen production stage: AOA generates oxygen under anaerobic conditions.

[0027] AOB oxidation stage: The AOB in the reactor utilizes the oxygen generated by AOA to oxidize approximately 60% of the ammonia nitrogen to generate nitrite nitrogen and maintains the anaerobic environment unchanged.

[0028] AnAOB nitrogen removal stage: The AnAOB in the reactor utilizes a part of the nitrite nitrogen generated by AOB oxidation and the remaining ammonia nitrogen to generate nitrate nitrogen and nitrogen gas, achieving low-carbon and high-efficiency ammonia removal treatment under fully anaerobic conditions.

[0029] The method for coupling ammonia-oxidizing archaea with anaerobic ammonia oxidation for nitrogen removal is specifically as follows: As Figure 2 shown, AOA and AnAOB are adapted to start with the new biological nitrogen removal method (1) Adding microorganisms, adapting AOA and AnAOB Introduce AnAOB sludge, AOA sludge, and AOB sludge into an upflow anaerobic sludge bed device with an effective volume of 4.5 L; among them, the volume of AnAOB sludge is 1.5 L, the MLSS is 3500 mg / L, and the quantity of AnAOB gene measured by qPCR is 0.73×10 6 copies / gVSS; the AOA sludge is the anaerobic sludge from a municipal sewage treatment plant, with a volume of 1.0 L, an MLSS of 3000 mg / L, and the quantity of AOA gene measured by qPCR is 6.14×10 6copies / gVSS; The AOB sludge is aerobic sludge from a municipal wastewater treatment plant, with a volume of 1.0 L, an MLSS of 2000 mg / L, and the number of AOB genes measured by qPCR is 4.34×10 6 copies / gVSS. After mixing in the upflow anaerobic sludge bed device, the numbers of AnAOB, AOA, and AOB genes in the mixed sludge measured by qPCR are 9.49×10 6 copies / gVSS, 8.36×10 6 copies / gVSS, and 1.32×10 8 copies / gVSS.

[0030] After inoculation, the sludge concentration MLSS in the reactor is 2280 mg / L. The device is heated by a water bath, and the water temperature is kept constant at 32 °C. The dissolved oxygen concentration in the influent substrate is controlled below 10 μg / L by nitrogen aeration.

[0031] Among them, the influent is simulated wastewater prepared with tap water. The hydraulic retention time HRT is 24 h, the influent alkalinity is 600 mg / L - 800 mg / L, provided by NaHCO3 (1000 mg / L - 1400 mg / L), ammonia nitrogen is provided by NH4Cl (0 mg / L - 800 mg / L), nitrite nitrogen is provided by NaNO2 (0 mg / L - 300 mg / L), and the influent pH is 8.0.

[0032] The composition and content in the simulated wastewater are 0.01 g / L KH2PO4, 0.01 g / L MgSO4, 0.03 g / L CaCl2·2H2O, 4.06 mg / L MnCl2·4H2O, 30 mg / L FeSO4·7H2O, 0.11 mg / L ZnSO4·7H2O, 0.10 mg / L NiCl2·6H2O, 1.1 mg / L Na2MoO4·2H2O, 0.04 mg / L CuSO4·5H2O, 0.12 mg / L CoCl2·6H2O, 0.13 mg / L H3BO4, 0.02 mg / L KI, 50 mg / L Na2·EDTA.

[0033] In Stage I - 1, the influent ammonia nitrogen and nitrite nitrogen concentrations are 200 mg / L and 264 mg / L respectively, the HRT is 24 h, the pH in the device is 8.0, and it runs for a total of 12 days. At the high influent concentrations of ammonia nitrogen and nitrite nitrogen, the average total nitrogen removal efficiency of the new process reaches 81.8%. It shows that AnAOB has good adaptability to the set high - concentration substrate environment.

[0034] Phase I-2, the influent ammonia nitrogen and nitrite nitrogen concentrations were 200 mg / L and 200 mg / L respectively, the HRT was 24 h, the pH in the device was 8.0, and it ran for 13 days in total. The average total nitrogen removal efficiency of the new process reached 68.3%, indicating that AOA, AOB, and AnAOB had good adaptability to the way of gradually reducing the influent nitrite nitrogen concentration.

[0035] Phase I-3, the influent ammonia nitrogen and nitrite nitrogen concentrations were 200 mg / L and 150 mg / L respectively, the HRT was 24 h, the pH in the device was 8.0, and it ran for 12 days in total. The average total nitrogen removal efficiency of the new process reached 57.9%, indicating that AOA, AOB, and AnAOB had good adaptability to the way of gradually reducing the influent nitrite nitrogen concentration.

[0036] Phase I-4, the influent ammonia nitrogen and nitrite nitrogen concentrations were 200 mg / L and 100 mg / L respectively, the HRT was 24 h, the pH in the device was 8.0, and it ran for 11 days in total. The average total nitrogen removal efficiency of the new process reached 51.9%.

[0037] After Phase I-1 to Phase I-4, the number of AOB genes decreased from 1.32×10 8 copies / gVSS in the mixed inoculated sludge to 6.69×10 7 copies / gVSS, the number of AnAOB genes increased from 9.49×10 6 copies / gVSS in the mixed inoculated sludge to 1.06×10 7 copies / gVSS, and the number of AOA genes increased from 8.36×10 6 copies / gVSS in the mixed inoculated sludge to 1.76×10 7 copies / gVSS. The results showed that the way of reducing the influent nitrite nitrogen concentration achieved the effective coexistence and high-efficiency nitrogen removal performance of AOA, AOB, and AnAOB in the device, and the new process met the requirements for entering the next stage of operation.

[0038] (2) Start-up of the new biological nitrogen removal method Phase II-1, the influent ammonia nitrogen and nitrite nitrogen concentrations were 200 mg / L and 0 mg / L respectively, the HRT was 24 h, the pH in the device was 8.0, and it ran for 11 days in total. The average total nitrogen removal efficiency of the new process reached 23.8%, indicating that AOA, AOB, and AnAOB had good adaptability to the cultivation method with the influent nitrite nitrogen concentration reduced to 0.

[0039] Stage II-2: The influent ammonia nitrogen and nitrite nitrogen concentrations were 150 mg / L and 0 mg / L respectively, the HRT was 24 h, the pH in the device was 8.0, and it ran for a total of 11 days. The average total nitrogen removal efficiency of the new process increased to 35.9%, indicating that after the influent nitrite concentration decreased to 0 mg / L, the decrease in the influent ammonia nitrogen concentration promoted the proliferation of AOA, AOB, and AnAOB.

[0040] Stage II-3: The influent ammonia nitrogen and nitrite nitrogen concentrations were 100 mg / L and 0 mg / L respectively, the HRT was 24 h, the pH in the device was 8.0, and it ran for a total of 12 days. The average total nitrogen removal efficiency of the new process increased to 49.5%.

[0041] After Stage II-1 to Stage II-3, the number of AOB genes decreased from 6.69×10 7 copies / gVSS in Stage I-4 to 1.89×10 7 copies / gVSS, the number of AnAOB genes remained at 1.04×10 7 copies / gVSS from 1.06×10 7 copies / gVSS in Stage I-4, and the number of AOA genes increased from 1.76×10 7 copies / gVSS in Stage I-4 to 6.32×10 7 copies / gVSS. The results show that after the influent nitrite concentration decreased to 0 mg / L, the way of decreasing the influent ammonia nitrogen concentration further achieved the proliferation balance of AOA, AOB, and AnAOB in the ecological niche.

[0042] Stage II-4: The influent ammonia nitrogen and nitrite nitrogen concentrations were 50 mg / L and 0 mg / L respectively, the HRT was 24 h, the pH in the device was 8.0, and it ran for a total of 11 days. The average total nitrogen removal efficiency of the new process increased to 64.5%,

[0043] The number of AOB genes remained at 1.90×10 7 copies / gVSS, the number of AnAOB genes remained at 1.11×10 7 copies / gVSS, and the number of AOA genes remained at 6.26×10 7 copies / gVSS. The results show that by controlling the influent nitrite concentration to decrease to 0 mg / L and gradually decreasing the influent ammonia nitrogen concentration to 50 mg / L, the new biological nitrogen removal method coupling ammonia-oxidizing archaea with anaerobic ammonia oxidation was rapidly started and highly efficient nitrogen removal treatment was achieved within 90 days, and AOA, AOB, and AnAOB maintained a stable proliferation balance.

[0044] The high influent ammonia nitrogen concentration of 200 mg / L set in Stage I is conducive to maintaining the activity and growth rate of AOB. The optimal growth pH of AOB is 7.8 - 8.2. By controlling the influent alkalinity concentration at 600 mg / L - 800 mg / L, the high activity of AOB can be improved in the system. Gradually reducing the influent nitrite nitrogen concentration in Stage I can improve the adaptability of AOA and AnAOB to the water quality environment with ammonia nitrogen as the only nitrogen source in the influent, thereby increasing the biomass of AOA and AnAOB in the system. In Stage II, gradually reducing the influent NH4 + -N concentration is beneficial to improving the activity of AOA and thus increasing the biomass of AOA in the system. Under anaerobic conditions, the oxygen produced by AOA can be rapidly utilized by AOB that has been domesticated to tolerate low oxygen concentrations, oxidizing ammonia nitrogen for AnAOB to utilize, thereby maintaining the proliferation of AOB and AnAOB. The water temperature in the upflow reactor is 30°C - 35°C, which is suitable for the proliferation of microorganisms.

[0045] It should be noted that when the claims of the present invention involve numerical ranges, it should be understood that any value between the two endpoints of each numerical range and the two endpoints can be selected. To avoid redundancy, the present invention describes preferred embodiments.

[0046] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications once they know the basic creative concept. Therefore, the appended claims are intended to be interpreted to include the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0047] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A method for biological denitrification of water, characterized in that: Adding microorganisms to raw water under an anaerobic environment, starting the biological denitrification method for water body, and then performing redox reaction to obtain denitrified water; The microorganisms are ammonia oxidizing archaea, ammonia oxidizing bacteria and anaerobic ammonia oxidizing bacteria; Wherein, the ammonia nitrogen concentration in the raw water is 40mg / L~60mg / L; The amount of ammonia oxidizing archaea added was 5×10 6 copies / gVSS~8×10 6 copies / gVSS; The amount of ammonia oxidizing bacteria added was 2×10 6 copies / gVSS~6×10 6 copies / gVSS; The amount of anaerobic ammonium oxidizing bacteria added was 0.5×10 6 copies / gVSS~2.0×10 6 copies / gVSS.

2. The method for biological denitrification of water according to claim 1, characterized in that: The temperature of the anaerobic environment is 30°C to 35°C.

3. The method for biological denitrification of water according to claim 1, characterized in that: The dissolved oxygen concentration in the anaerobic environment is ≤10 μg / L.

4. The method for biological denitrification of water according to claim 1, characterized in that: The pH of the raw water is 7.8-8.

2.

5. The method for biological denitrification of water according to claim 1, characterized in that: The startup includes the following steps: AOA and AnAOB adaptation stage: sludge containing AnAOB microorganisms, sludge containing AOA microorganisms and sludge containing AOB microorganisms are inoculated into the anaerobic environment, and raw water is inoculated into the anaerobic environment; the ammonia nitrogen of the raw water is 200 mg / L, the nitrite nitrogen concentration of the raw water is gradually reduced from 264 mg / L to 100 mg / L, and the alkalinity concentration of the raw water is 600 mg / L~800 mg / L; Start-up phase: the ammonia nitrogen concentration of the raw water gradually decreases from 200 mg / L to 50 mg / L, the nitrite nitrogen concentration of the raw water is 0 mg / L, and the alkalinity concentration of the raw water is 600 mg / L~800 mg / L.

6. The method for biological denitrification of water according to claim 5, characterized in that: The water inlet method is continuous water inlet.

7. The method for biological denitrification of water according to claim 5, characterized in that: In the process of gradually reducing the nitrite nitrogen concentration, when the total nitrogen removal rate reaches 60% at the previous nitrite nitrogen concentration, the nitrite nitrogen concentration is reduced.

8. The method for biological denitrification of water according to claim 7, characterized in that: Each nitrite nitrogen concentration range runs for 14 to 17 days.

9. The method for biological denitrification of water according to claim 5, characterized in that: In the process of gradually reducing the ammonia nitrogen concentration, when the total nitrogen removal rate reaches 40% at the previous ammonia nitrogen concentration, the ammonia nitrogen concentration is reduced.

10. The method for biological denitrification of water according to claim 9, characterized in that: Each ammonia nitrogen concentration was run for 14 to 17 days.

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