An integrated method of coagulation sedimentation-short-term nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonium oxidation

Abstract

The present invention relates to a coagulation sedimentation-short-range nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonia oxidation integrated method. Ferrous sulfate or ferric chloride is selected as a coagulant to optimize the dosage. Subsequently, short-range nitrification activated sludge is introduced into the SBR reactor, and denitrification sludge and iron ammonia oxidation sludge are gradually introduced. By adjusting the dissolved oxygen level and pH value, ammonia nitrogen is oxidized into nitrite, nitrate and nitrogen through nitrification and iron ammonia oxidation; in the UASB reactor of the second section, anaerobic ammonia oxidation granular sludge is domesticated in stages to directly convert ammonia nitrogen and nitrite into nitrogen. Compared with the prior art, the present invention improves nitrogen treatment efficiency by introducing iron ammonia oxidation process and iron autotrophic denitrification process. Trivalent iron acts as an electron acceptor of Feammox to oxidize ammonia nitrogen; organic carbon and ferrous iron jointly provide electron donors for denitrification to enhance nitrate nitrogen removal; the Feammox system promotes the removal of refractory organic matter. And low concentration iron can promote the Anammox process and improve system efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a coagulation sedimentation-short-range nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonia oxidation integrated method. Background Art

[0002] Anaerobic digestion is a method for treating organic waste and achieving energy recovery. During the anaerobic digestion process, organic matter is decomposed into biogas and biogas liquid. This method is widely used in the treatment of organic waste such as food waste, urban sludge, livestock and poultry manure. The biogas liquid produced by anaerobic digestion contains a large amount of organic matter and nutrients, especially ammonia nitrogen. Therefore, whether it is directly discharged or reused as fertilizer or cultivation mother liquid, ammonia nitrogen must be effectively removed to prevent pollution to the environment.

[0003] Traditional sewage treatment technologies face problems such as low treatment efficiency, high energy consumption and secondary pollution. In recent years, anaerobic ammonia oxidation technology (Anammox) has attracted research attention due to its advantages of high efficiency and low energy consumption. However, Anammox technology produces byproducts such as nitrate nitrogen during the treatment process, which require further treatment to meet emission standards. Therefore, it is urgent to study more efficient and sustainable wastewater treatment technologies. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a coagulation sedimentation-short-term nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonia oxidation integrated method, which is a PN / DN / Feammox-Anammox process, which treats sewage through short-term nitrification / denitrification / Feammox coupled with Anammox, and introduces iron ammonia oxidation (Feammox) and autotrophic denitrification processes, aiming to solve the shortcomings of the prior art, which not only improves the treatment efficiency and system stability, but also significantly reduces the operating cost and environmental impact.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] The object of the present invention is to provide a coagulation sedimentation-short-range nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonium oxidation integrated method, which is used to remove nitrogen from sewage, and the method comprises the following steps:

[0007] S1. Front-end pretreatment: According to the influent characteristics, iron salt is selected as the coagulant and the dosage of the coagulant is adjusted to perform coagulation and sedimentation;

[0008] S2. Start-up of short-range nitrification / denitrification / Feammox: inoculation and cultivation of microorganisms, optimization of short-range nitrification / autotrophic denitrification / heterotrophic denitrification / Feammox process by setting up aeration system to automatically adjust dissolved oxygen level, cycle time and pH;

[0009] S3. Start-up of Anammox: Inoculate granular sludge and adopt a phased acclimation strategy, first adapt to artificial water distribution with low concentrations of ammonia nitrogen and nitrite nitrogen, then increase the proportion of actual sewage and adjust to the same conditions as the actual sewage. Monitor the activity of Anammox throughout the process to ensure the effective operation of the microbial process of Anammox in the actual sewage treatment system;

[0010] S4. System operation: Combine intermittent aeration and internal circulation to optimize the nitrogen conversion pathway of the entire biogas slurry nitrogen treatment system. When the total nitrogen removal rate of the system reaches more than 90% and can be maintained for 20 days, the process is considered to have reached a stable operating state. Continuously monitor the temperature, inlet C / N ratio and hydraulic retention time of each reactor. Adjust the operating parameters in time according to the monitoring results to ensure the long-term efficient and stable operation of the system and achieve the removal of nitrogen in the sewage.

[0011] Furthermore, in step S1, the iron salt is at least one of ferrous sulfate or ferric chloride; and the dosage of the iron salt is between 10-30 mg / L.

[0012] Furthermore, in step S1, the specific process of the coagulation and sedimentation is as follows: using high-efficiency coagulation and sedimentation technology, that is, using the Turbo-LME high-speed sedimentation tank to perform sludge coagulation (destabilization, sludge contact, flocculation) and pH adjustment (adjusting the inlet pH to 6.5-7.5) to optimize the coagulation effect of iron salts, with a suspended solids removal rate of >90% and a COD removal rate of 20%-30%.

[0013] Furthermore, step S2 includes the following specific process:

[0014] Inoculation and cultivation of microorganisms: Sludge is initially inoculated in a reactor, and a periodic water inlet and aeration strategy is adopted. The aeration strategy includes dynamically changing the oxygen supply so that the system continuously switches between anoxic and aerobic states. This method can cultivate microorganisms that adapt to different oxygen levels (especially nitrite microorganisms, Feammox microorganisms, autotrophic denitrification microorganisms, and heterotrophic denitrification microorganisms). Short-range nitrification microorganisms oxidize ammonia nitrogen into nitrite, and Feammox microorganisms use iron ions (Fe(III)) as electron acceptors to oxidize ammonia nitrogen into nitrite, nitrate nitrogen, and nitrogen gas. Heterotrophic denitrification microorganisms use organic carbon as an electron donor to reduce nitrate and nitrite to nitrogen gas. At the same time, the presence of ferrous ions enhances the denitrification process. Autotrophic denitrification microorganisms use ferrous ions as electron donors and nitrate nitrogen as electron acceptors. Therefore, ferrous ions and organic carbon jointly promote the removal of nitrate nitrogen, thereby improving the nitrogen treatment efficiency and stability of the system. In addition, iron promotes the growth of dissimilatory iron-reducing bacteria, which use ferric iron as an electron acceptor to remove COD. A significant advantage of the Feammox system is that it can enrich a large number of dissimilatory iron-reducing bacteria (IRB), which can decompose some difficult-to-degrade carbon sources, such as hemicellulose, lignin, and cellulose. Therefore, coupling the Feammox process helps to reduce the organic load in the anaerobic ammonium oxidation stage and can more effectively treat difficult-to-degrade organic matter. The above process can also realize the cyclic conversion between Fe(III) and Fe(II). During Feammox and dissimilatory iron reduction, Fe(III) is reduced to Fe(II), while during aeration and autotrophic denitrification, Fe(II) is oxidized back to Fe(III). This cycle not only improves the recycling rate of iron, but also enhances the system's buffering capacity against changing environments, such as pH fluctuations and changes in redox potential.

[0015] By setting up an aeration system, i.e. installing dissolved oxygen probes throughout the reactor to monitor oxygen levels, and installing a control device to dynamically adjust the variable speed blower or fine bubble diffuser based on real-time feedback, the short-cut nitrification / denitrification / Feammox process is optimized by automatically adjusting the dissolved oxygen level to below 0.5mg / L anoxic, 2-3mg / L aerobic, a cycle time of 6 hours per cycle, including 1.5 hours anoxic, 3 hours aerobic, 1.5 hours re-anoxic, and a pH of 7.0-8.0.

[0016] Furthermore, in step S2, the sludge is one or more of short-range nitrification activated sludge, denitrification sludge, and iron-ammonia oxidation sludge; in step S2, the initial sludge concentration is 3000-4000 mg / L.

[0017] Furthermore, in step S2, the first stage reactor is an SBR reactor.

[0018] Furthermore, step S3 includes the following specific process:

[0019] Inoculate anaerobic ammonium oxidation granular sludge in the second-stage reactor to ensure efficient biological reaction in the reactor;

[0020] A phased acclimation strategy was adopted, with artificial water distribution with low concentrations of ammonia nitrogen and nitrite nitrogen being used for adaptive acclimation, with ammonia nitrogen concentration of about 50-100 mg / L and nitrite nitrogen concentration of about 66-132 mg / L, and then the proportion of actual sewage was gradually increased to adjust to the conditions exactly the same as those of actual sewage, while monitoring Anammox activity throughout the process to ensure its stable operation in actual sewage. Artificial water distribution was adjusted to be exactly the same as the conditions of actual sewage by gradually introducing actual sewage in stages over 2-4 weeks. During this period, the concentrations of ammonia nitrogen and nitrite nitrogen were precisely adjusted to reflect the final sewage composition, and additional nutrients were supplemented to replicate the chemical characteristics of sewage, including acetate or propionate to simulate organic carbon content, phosphate to simulate phosphorus content (0.5-1 mg / L), and trace elements such as zinc (0.05-0.2 mg / L). Sodium bicarbonate is added to adjust alkalinity and maintain pH between 7.0-8.0, while temperature (30-35°C) and dissolved oxygen levels (<0.5 mg / L) are tightly controlled to ensure optimal Anammox activity. This comprehensive supplementation ensures a seamless transition to real sewage conditions. At the same time, the right amount of ferrous and ferric ions can enhance the efficiency of the Anammox process.

[0021] Furthermore, in step S3, the second-stage reactor is a UASB reactor; in step S3, the particle size of the anaerobic ammonium oxidation granular sludge is between 0.5-1.0 mm.

[0022] Furthermore, step S4 includes the following specific process:

[0023] Combine intermittent aeration and internal circulation to optimize the nitrogen conversion pathway of the entire biogas slurry nitrogen treatment system;

[0024] When the total nitrogen removal rate of the system reaches more than 90% and is maintained for 20 days, the process is considered to have reached a stable operating state;

[0025] Continuously monitor the temperature, inlet C / N ratio and hydraulic retention time of each reactor, maintain the temperature at 20-30℃, the inlet C / N ratio at 4:1 to 6:1, the hydraulic retention time of each reactor at 6 hours for SBR and 6-8 hours for UASB, and adjust the operating parameters in time according to the monitoring results to ensure the long-term efficient and stable operation of the system.

[0026] Furthermore, in step S4, the internal circulation reflux ratio is set to 100%-150% to ensure effective conversion of nitrogen in different treatment stages.

[0027] Furthermore, the method specifically comprises the following steps:

[0028] S1. Front-end preprocessing:

[0029] Coagulant selection and dosage: According to the influent characteristics, ferrous sulfate or ferric chloride is selected as the coagulant. The dosage is adjusted according to the water quality test results, usually between 10-30 mg / L, to ensure sufficient iron ions to participate in the subsequent Feammox process.

[0030] Coagulation and sedimentation technology details: Adopting high-efficiency coagulation and sedimentation technology, the inlet pH is adjusted to 6.5-7.5 through the Turbo-LME high-speed sedimentation tank control system, optimizing the coagulation effect of iron salts, with a suspended solids removal rate of >90% and a COD removal rate of 20%-30%.

[0031] S2. Start-up of short-range nitrification / denitrification / Feammox:

[0032] Microbial inoculation and cultivation: Use SBR reactors to initially inoculate short-range nitrification activated sludge, gradually introduce denitrification sludge and Feammox sludge, and adjust the initial sludge concentration to 3000-4000 mg / L. Use periodic water inflow and aeration strategies to simulate oxygen concentration fluctuations in the natural environment to promote the formation and stability of specific microbial communities.

[0033] Fine control of operating parameters: The short-range nitrification / denitrification / Feammox process is optimized by setting the aeration system to automatically adjust the dissolved oxygen level (below 0.5 mg / L for anoxic, 2-3 mg / L for aerobic), cycle time (6 hours per cycle, including 1.5 hours of anoxic, 3 hours of aerobic, and 1.5 hours of re-anoxic) and pH (7.0-8.0).

[0034] S3. Startup of Anammox:

[0035] Characteristics of granular sludge: Anaerobic ammonium oxidation granular sludge is inoculated in the second-stage UASB reactor. Anaerobic ammonium oxidation granular sludge with a particle size of 0.5-1.0 mm is selected, which has high biological activity and good sedimentation performance, ensuring the efficient biological reaction in the reactor.

[0036] System acclimation and adaptation: A phased acclimation strategy is adopted. First, the system is adapted to artificial water with low concentrations of ammonia nitrogen and nitrite nitrogen. The concentration of ammonia nitrogen is about 50-100 mg / L, and the concentration of nitrite nitrogen is about 66-132 mg / L. Then, the proportion of actual sewage is gradually increased to adjust to the conditions that are exactly the same as those of actual sewage. The activity of Anammox is monitored throughout the process to ensure its stable operation in actual sewage. This process takes 2-4 weeks.

[0037] S4.System operation:

[0038] Optimization of nitrogen conversion path: Combined with the internal circulation reflux of intermittent aeration method, the nitrogen conversion path of the entire treatment system is optimized. The internal circulation reflux ratio is set to 100%-150% to ensure the effective conversion of nitrogen in different treatment stages.

[0039] Stability index: When the total nitrogen removal rate of the system reaches more than 90% and can be maintained for 20 days, the process is considered to have reached a stable operating state.

[0040] Monitoring and adjustment: Continuously monitor the temperature (20-30℃), inlet C / N ratio (4:1 to 6:1) and hydraulic retention time of each reactor (SBR about 6 hours, UASB about 6-8 hours), and adjust the operating parameters in time according to the monitoring results to ensure the long-term efficient and stable operation of the system.

[0041] This technical solution achieves efficient removal of nitrogen from sewage by finely controlling the operating parameters and environmental conditions at each stage. This solution has good environmental adaptability and stability, and is suitable for sewage treatment projects of various sizes, especially for the treatment of high ammonia nitrogen wastewater.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. Multiple effects of iron ions: The present invention not only achieves preliminary water quality adjustment by introducing iron salts in the pretreatment stage, but also provides the necessary trivalent iron ions for the Feammox process, which participates in the oxidation of ammonia nitrogen as an electron acceptor. At the same time, the addition of ferrous ions enhances the denitrification process, and autotrophic denitrifying microorganisms use ferrous ions as electron donors and nitrate nitrogen as electron acceptors. Therefore, ferrous ions and organic carbon jointly promote the removal of nitrate nitrogen, thereby improving the nitrogen treatment efficiency and stability of the system. In addition, iron also promotes the growth of dissimilatory iron-reducing bacteria, which use trivalent iron as an electron acceptor to remove COD; a significant advantage of the Feammox system is that it can enrich a large number of dissimilatory iron-reducing bacteria (Iron-Reducing Bacteria, IRB), which can decompose some difficult-to-degrade carbon sources, such as hemicellulose, lignin and cellulose. Therefore, coupling the Feammox process helps to reduce the organic load of the anaerobic ammonia oxidation section and can more effectively treat difficult-to-degrade organic matter. At the same time, an appropriate amount of ferrous ions and ferric ions can significantly improve the efficiency of the Anammox process, realize the effective utilization of iron ions in the entire treatment process, and improve the treatment efficiency and system stability.

[0044] 2. Utilization of Fe(III) / Fe(II) formation cycle: The present invention effectively realizes the cyclic conversion between Fe(III) and Fe(II), and optimizes the utilization efficiency of iron. During the Feammox and dissimilatory iron reduction processes, Fe(III) is reduced to Fe(II), and during the aeration process and autotrophic denitrification process, Fe(II) is oxidized back to Fe(III). This cycle not only improves the recycling rate of iron, but also enhances the system's buffering capacity for changing environments, such as pH fluctuations and changes in redox potential. This dynamic balance helps maintain biochemical activity within the reactor and ensures the continuity and efficiency of the treatment process. Through this iron ion circulation mechanism, the system can more stably treat high-concentration nitrogen wastewater, while reducing the need for external chemical additives and enhancing the economy and environmental protection of the system.

[0045] 3. Optimization of the integrated biological treatment process: By finely controlling the operating parameters of the short-range nitrification / denitrification / Feammox and Anammox processes, the present invention achieves efficient nitrogen conversion, significantly reduces operating costs and environmental impacts, and is suitable for sewage treatment projects of various scales, especially for the treatment of high ammonia nitrogen wastewater.

[0046] 4. System stability and adaptability: The use of advanced monitoring and control systems enables precise control and real-time adjustment of the entire treatment process, ensuring efficient and stable operation of the system and improving its adaptability to changes in sewage quality. DETAILED DESCRIPTION

[0047] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0048] Any features such as preparation methods, materials, structures or composition ratios that are not clearly described in this technical solution shall be deemed as common technical features disclosed in the prior art.

[0049] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0050] It should be noted that, in the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0051] The present invention provides a coagulation sedimentation-short-term nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonium oxidation integrated method, which combines short-term nitrification / autotrophic denitrification / heterotrophic denitrification / Feammox-anaerobic ammonium oxidation processes, aiming to improve the efficiency of organic waste treatment and reduce environmental impact. Specifically, by carefully selecting ferrous sulfate or ferric chloride as a coagulant and adjusting the dosage to 10-30 mg / L, this technology optimizes the coagulation sedimentation process. Using an SBR reactor, this technology starts with short-term nitrification activated sludge, gradually introduces denitrification sludge and iron ammonia oxidation (Feammox) sludge, and automatically adjusts the aeration system to maintain the dissolved oxygen level and pH value, thereby effectively coupling the short-term nitrification / autotrophic denitrification / heterotrophic denitrification / Feammox process. In the second stage of the UASB reactor, a staged acclimation strategy is adopted to inoculate anaerobic ammonium oxidation granular sludge with a particle size of 0.5-1.0 mm to adapt to the front-end effluent conditions. The stable operation of the system is ensured by continuously monitoring the temperature, influent C / N ratio and hydraulic retention time. This technology improves the overall nitrogen removal rate by introducing the Feammox process and the iron autotrophic denitrification process. Trivalent iron acts as an electron acceptor for Feammox to oxidize ammonia nitrogen; organic carbon and ferrous iron together provide electron donors for denitrification, enhancing the removal of nitrate nitrogen, and low concentrations of iron can promote the Anammox process, thereby promoting the efficient operation of the entire treatment process, showing broad application potential.

[0052] The present invention provides a short-range nitrification / denitrification / FEAMMOX-anaerobic ammonium oxidation integrated method for biogas slurry treatment. Ferrous sulfate or ferric chloride is selected as a coagulant, and the dosage is optimized to 10-30 mg / L to improve the coagulation and sedimentation process. Subsequently, a two-stage treatment is adopted: first, a short-range nitrification activated sludge is introduced into the SBR reactor, and denitrification sludge and iron ammonia oxidation (Feammox) sludge are gradually introduced. By adjusting the dissolved oxygen level and pH value, the coupling of short-range nitrification / denitrification / Feammox is achieved, and ammonia nitrogen is oxidized into nitrite, nitrate and nitrogen through nitrification and iron ammonia oxidation, wherein nitrate nitrogen is converted into nitrogen through heterotrophic denitrification and iron autotrophic denitrification, and part of nitrite nitrogen is removed by denitrification; in the second section of the UASB reactor, the anaerobic ammonium oxidation granular sludge is domesticated in stages, and ammonia nitrogen and nitrite are directly converted into nitrogen. Compared with the prior art, the present invention improves the nitrogen treatment efficiency by introducing the iron ammonia oxidation process and the iron autotrophic denitrification process. Ferric iron acts as an electron acceptor for Feammox, oxidizing ammonia nitrogen; organic carbon and ferrous iron together provide electron donors for denitrification, enhancing the removal of nitrate nitrogen; the Feammox system promotes the removal of refractory organic matter. Low concentrations of iron can promote the Anammox process, improve system efficiency, and show broad application potential.

[0053] Short-range nitrification activated sludge comes from the activated sludge system of urban sewage treatment plants, which are specialized in treating domestic sewage with high ammonia nitrogen content. Denitrification sludge is taken from the activated sludge system of industrial wastewater treatment plants. The wastewater treated here often contains rich nitrates and organic matter, which provides a good basis for the denitrification process. Feammox sludge is cultivated in the laboratory. By adding iron ions and ammonia nitrogen under a controlled environment, microorganisms that can use iron ions as electron acceptors for ammonia oxidation are cultivated. Anaerobic ammonia oxidation granular sludge is taken from the anaerobic ammonia oxidation section of the sewage treatment plant, which is specialized in domesticating and maintaining efficient anaerobic ammonia oxidation microbial communities.

[0054] Embodiment 1:

[0055] This embodiment provides a coagulation sedimentation-short-range nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonium oxidation integrated method, which is as follows:

[0056] Take the biogas slurry produced by anaerobic digestion in a certain treatment plant, with ammonia nitrogen of 1683mg / L and COD of 2612mg / L. Ferrous sulfate is selected as a coagulant, and the dosage is set to 25mg / L. High-efficiency coagulation and precipitation technology (the specific technology can be referred to DOI:10.15890 / j.cnki.jsjs.2012.01.020, DOI:10.13789 / j.cnki.wwe1964.2013.12.007), that is, the Turbo-LME high-speed sedimentation tank is used to adjust the influent pH to 7.0. This link can achieve a suspended solids removal rate of more than 90% and a COD removal rate of 25%. In the SBR reactor with an effective volume of 6L, short-range nitrification activated sludge is initially inoculated, and denitrification sludge and iron ammonia oxidation (Feammox) sludge are gradually introduced, and the initial sludge concentration is adjusted to 3500mg / L. The aeration system is set to automatically adjust the dissolved oxygen level to 2-3 mg / L in the aerobic stage and below 0.5 mg / L in the anoxic stage. The aeration system includes the following substructures, all of which are prior art: microporous aeration system (model Sanitaire Silver Series II), dissolved oxygen sensor (YSIProDSS portable multi-parameter water quality analyzer), dissolved oxygen controller (WTW IQ SensorNet 2020), and automatic control system (Siemens SIMATIC S7 programmable logic controller). Working principle of aeration system: Aerator and air supply system: The aerator introduces air into the reactor through a blower or compressed air supply system. The aerator selects microporous aerator or mechanical aerator and combines it with the air supply system to achieve efficient aeration. Dissolved oxygen monitoring and control: The dissolved oxygen sensor monitors the dissolved oxygen level in the reactor in real time. The dissolved oxygen controller transmits the monitoring data to the PLC or DCS control system. The dissolved oxygen target values ​​for the aerobic and anoxic stages are preset: Aerobic stage: The dissolved oxygen level is maintained at 2-3 mg / L. Anoxic stage: The dissolved oxygen level is controlled below 0.5 mg / L. The PLC or DCS control system automatically adjusts the blower speed or aeration volume to achieve the target dissolved oxygen level. The cycle is set to 6 hours, including 1.5 hours of anoxic, 3 hours of aerobic, and another 1.5 hours of anoxic. The pH is controlled at 7.5 and the temperature is controlled at 25±2°C. Anaerobic ammonia oxidation granular sludge with good sedimentation performance is inoculated in a UASB reactor with an effective volume of 6L, and the particle size is selected as 0.75mm. A staged acclimation strategy is adopted. First, the system is adapted to the water distribution of 100 mg / L ammonia nitrogen and 132 mg / L nitrite nitrogen. Then the actual sewage ratio is gradually increased and adjusted to the same conditions as the actual sewage. The activity of Anammox (anaerobic ammonia oxidation bacteria) is monitored to ensure its stable operation. This process lasts for 3 weeks.The SBR reactor cycle was set to 6 hours using intermittent aeration combined with internal circulation, including: 1.5 hours of anoxic (A1): Set the aeration system to stop running and maintain stirring to ensure mixing. Control the dissolved oxygen level to be below 0.5 mg / L. The pH was controlled at 7.5. 3 hours of aerobic (O): Set the aeration system to start and automatically adjust the dissolved oxygen level to 2-3 mg / L. The pH was controlled at 7.5. 1.5 hours of anoxic (A2): Set the aeration system to stop running and maintain stirring to ensure mixing. Control the dissolved oxygen level to be below 0.5 mg / L. The pH was controlled at 7.5. The temperature was controlled at 25±2℃. The internal circulation reflux ratio was set to 125%, SBR for about 6 hours, and UASB for about 6 hours. Eventually, the total nitrogen removal rate of the system was stabilized at more than 90.6%, and the COD removal rate was stabilized at more than 52.4%, which were maintained for more than 20 days. During this period, the temperature (20-30℃), inlet C / N ratio (4:1 to 6:1) and hydraulic retention time of each reactor (about 6 hours for SBR and about 6-8 hours for UASB) were continuously monitored to ensure the normal operation of the system.

[0057] Comparative Example 1:

[0058] Take the biogas slurry produced by anaerobic digestion in a local treatment plant, with ammonia nitrogen of 1683 mg / L and COD of 2612 mg / L. After filtering, the above biogas slurry is put into a short-range nitrification reactor with an effective volume of 6L, the temperature is controlled at 25±2℃, the pH is automatically adjusted to 7.5, the dissolved oxygen level is adjusted to above 2mg / L, and the hydraulic retention time is 6h. The treated biogas slurry then flows into the stable anaerobic ammonia oxidation section obtained by artificial water distribution and domestication for further treatment. During the treatment process of this section, the total nitrogen removal rate of the system is finally stabilized at more than 72.3%, and the COD removal rate is stabilized at more than 43.3%, which is maintained for 5 days.

[0059] It can be seen that compared with Comparative Example 1, the ammonia nitrogen removal rate of Example 1 is increased by 18.3%, the organic matter removal rate is increased by 9.1%, and the duration is longer.

[0060] Embodiment 2:

[0061] This embodiment provides a coagulation sedimentation-short-range nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonium oxidation integrated method, which is as follows:

[0062] Take the biogas produced by anaerobic digestion in a local treatment plant, with ammonia nitrogen of 1539mg / L and COD of 2496mg / L. Ferrous sulfate is selected as a coagulant, and the dosage is set to 20mg / L. Using high-efficiency coagulation and sedimentation technology, the influent pH is adjusted to 7.2 using the Turbo-LME high-speed sedimentation tank. This link can achieve a suspended solids removal rate of more than 90% and a COD removal rate of 24%. In an SBR reactor with an effective volume of 6L, short-range nitrification activated sludge is initially inoculated, and denitrification sludge and Feammox sludge are gradually introduced. The initial sludge concentration is adjusted to 3200mg / L. Adjust the dissolved oxygen level to 2-3mg / L in the aerobic stage and below 0.5mg / L in the anoxic stage. The cycle is set to 6 hours, including 1.5 hours of anoxic, 3 hours of aerobic, and another 1.5 hours of anoxic, pH is controlled at 7.2, and the temperature is controlled at 25±2℃. Anaerobic ammonium oxidation granular sludge with good sedimentation performance was inoculated in a UASB reactor with an effective volume of 6L, and the particle size was selected to be 1mm. A phased acclimation strategy was adopted. First, the system was adapted with 50mg / L ammonia nitrogen and 66mg / L nitrite nitrogen. Then the actual sewage ratio was gradually increased and adjusted to the same conditions as the actual sewage. The activity of Anammox was monitored to ensure its stable operation. This process lasted for 4 weeks. Through intermittent aeration combined with internal circulation reflux, the internal circulation reflux ratio was set to 112%, SBR was about 6 hours, and UASB was about 6 hours. Finally, the total nitrogen removal rate of the system was stabilized at more than 92.5%, and the COD removal rate was stabilized at more than 54.6%, which was maintained for more than 20 days.

[0063] Comparative Example 2:

[0064] Take the biogas produced by anaerobic digestion in a local treatment plant, with ammonia nitrogen of 1539 mg / L and COD of 2496 mg / L. After filtering, the above biogas was put into a short-range nitrification reactor with an effective volume of 6L, the temperature was controlled at 25±2℃, the pH was automatically adjusted to 7.2, the dissolved oxygen level was adjusted to above 2mg / L, and the hydraulic retention time was 6h. Anaerobic ammonia oxidation granular sludge with good sedimentation performance was inoculated in a UASB reactor with an effective volume of 6L, and the particle size was selected as 1mm. A phased acclimation strategy was adopted. First, the system was adapted with 50mg / L ammonia nitrogen and 66mg / L nitrite nitrogen. Then the actual sewage ratio was gradually increased and adjusted to the same conditions as the actual sewage. The activity of Anammox was monitored to ensure its stable operation. This process lasted for 4 weeks. Finally, the total nitrogen removal rate of the system was stabilized at more than 75.2%, and the COD removal rate was stabilized at more than 45.2%, which was maintained for 9 days.

[0065] It can be seen that compared with Comparative Example 2, the ammonia nitrogen removal rate of Example 2 is increased by 17.3%, the organic matter removal rate is increased by 9.4%, and the duration is longer.

[0066] Embodiment 3:

[0067] This embodiment provides a coagulation sedimentation-short-range nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonium oxidation integrated method, which is as follows:

[0068] Take the biogas produced by anaerobic digestion in a local treatment plant, with ammonia nitrogen of 1852 mg / L and COD of 2563 mg / L. Ferric chloride is selected as a coagulant, and the dosage is set to 30 mg / L. Using high-efficiency coagulation and sedimentation technology, the influent pH is adjusted to 6.8 through the Turbo-LME high-speed sedimentation tank. This link can achieve a suspended solids removal rate of more than 90% and a COD removal rate of 28%. In an SBR reactor with an effective volume of 6L, short-range nitrification activated sludge is initially inoculated, and denitrification sludge and iron ammonia oxidation (Feammox) sludge are gradually introduced. The initial sludge concentration is adjusted to 4000 mg / L. Adjust the dissolved oxygen level to 2-3 mg / L in the aerobic stage and below 0.5 mg / L in the anoxic stage. The cycle is set to 6 hours, including 1.5 hours of anoxic, 3 hours of aerobic, and another 1.5 hours of anoxic, pH is controlled at 6.8, and the temperature is controlled at 25±2℃. Anaerobic ammonium oxidation granular sludge with good sedimentation performance was inoculated in a UASB reactor with an effective volume of 6L, and the particle size was selected to be 0.6mm. A phased acclimation strategy was adopted. First, the system was adapted with water distribution of 100mg / L ammonia nitrogen and 132mg / L nitrite nitrogen, and then the actual sewage ratio was gradually increased and adjusted to the same conditions as the actual sewage. The activity of Anammox was monitored to ensure its stable operation. This process lasted for 3.5 weeks. Through intermittent aeration combined with internal circulation reflux, the internal circulation reflux ratio was set to 120%, SBR was about 6 hours, and UASB was about 6 hours. Finally, the total nitrogen removal rate of the system was stabilized at more than 92.8%, and the COD removal rate was stabilized at more than 55.2%, which was maintained for more than 20 days.

[0069] Comparative Example 3:

[0070] Take the biogas produced by anaerobic digestion in a local treatment plant, with ammonia nitrogen of 1852 mg / L and COD of 2563 mg / L. Ferric chloride is selected as a coagulant, and the dosage is set to 30 mg / L. Adjust the influent pH to 6.8. This link can achieve a suspended solids removal rate of more than 90% and a COD removal rate of 28%. In an SBR reactor with an effective volume of 6L, short-range nitrification activated sludge is initially inoculated, the initial sludge concentration is adjusted to 3500 mg / L, the temperature is controlled at 25±2℃, the pH is automatically adjusted to 7.2, the dissolved oxygen level is adjusted to above 2 mg / L, and the hydraulic retention time is 6h. Anaerobic ammonia oxidation granular sludge with good sedimentation performance is inoculated in a UASB reactor with an effective volume of 6L, and the particle size is selected to be 0.6mm. A phased acclimation strategy was adopted. First, the system was adapted to the water distribution of 100 mg / L ammonia nitrogen and 132 mg / L nitrite nitrogen. Then the proportion of actual sewage was gradually increased and adjusted to the same conditions as the actual sewage. The activity of Anammox was monitored to ensure its stable operation. This process lasted for 3.5 weeks. Finally, the total nitrogen removal rate of the system was stabilized at more than 79.9%, and the COD removal rate was stabilized at more than 47.3%, which was maintained for 12 days.

[0071] It can be seen that compared with Comparative Example 3, the ammonia nitrogen removal rate of Example 3 is increased by 12.9%, the organic matter removal rate is increased by 7.9%, and the duration is longer.

[0072] The above description of the embodiments is to facilitate the understanding and application of the present invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the embodiments herein, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

[0073] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A coagulation sedimentation-short-term nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonium oxidation integrated method, characterized in that: The method is used to remove nitrogen from sewage, and the method comprises the following steps: S1. Front-end pretreatment: According to the influent characteristics, iron salt is selected as the coagulant and the dosage of the coagulant is adjusted to perform coagulation and sedimentation; S2. Start-up of short-range nitrification / denitrification / Feammox: Inoculate and cultivate microorganisms, optimize the short-range nitrification / denitrification / Feammox process by setting up the aeration system to automatically adjust the dissolved oxygen level, cycle time and pH. Step S2 realizes the cyclic conversion between Fe(III) and Fe(II). During Feammox and dissimilatory iron reduction, Fe(III) is reduced to Fe(II), while during aeration and autotrophic denitrification, Fe(II) is oxidized back to Fe(III). ; Step S2 includes the following specific processes: inoculation and cultivation of microorganisms: sludge is initially inoculated in a reactor, and a periodic water inlet and aeration strategy is adopted. The aeration strategy includes dynamically changing the oxygen supply so that the system continuously switches between anoxic and aerobic states, providing an aerobic environment for nitrifying microorganisms, and providing anoxic environments for Feammox microorganisms, heterotrophic denitrifying microorganisms, and autotrophic denitrifying microorganisms, thereby improving the overall treatment efficiency of the reactor; by setting up an aeration system, a dissolved oxygen probe is installed throughout the reactor to monitor the oxygen level, and a control device is installed at the same time, and a variable speed blower or a fine bubble diffuser is dynamically adjusted according to real-time feedback, and the dissolved oxygen level is automatically adjusted to below 0.5 mg / L for anoxic, 2-3 mg / L for aerobic, and the cycle time is 6 hours per cycle, including 1.5 hours of anoxic, 3 hours of aerobic, 1.5 hours of re-anoxic and pH of 7.0-8.0 to optimize the short-range nitrification / denitrification / Feammox process; S3. Anammox startup: inoculate granular sludge and adopt a phased acclimation strategy, first adapt to artificial water distribution with low concentrations of ammonia nitrogen and nitrite nitrogen, then increase the proportion of actual sewage and adjust to the same conditions as the actual sewage. Monitor Anammox activity throughout the process to ensure the effective operation of the Anammox microbial process in the actual sewage treatment system; S4. System operation: Combine intermittent aeration and internal circulation to optimize the nitrogen conversion path of the entire biogas slurry nitrogen treatment system; when the total nitrogen removal rate of the system reaches more than 90% and is maintained for 20 days, the process is considered to have reached a stable operation state; continuously monitor the temperature, influent C / N ratio and hydraulic retention time of each reactor, maintain the temperature at 20-30℃, the influent C / N ratio at 4:1 to 6:1, and the hydraulic retention time of each reactor at 6 hours for SBR and 6-8 hours for UASB, and adjust the operating parameters according to the monitoring results to ensure the operation of the system; In step S1, the iron salt is at least one of ferrous sulfate or ferric chloride; the dosage of the iron salt is between 10-30 mg / L; In step S2, the sludge is one or more of short-range nitrification activated sludge, denitrification sludge, and iron-ammonia oxidation sludge; in step S2, the initial concentration of the sludge is 3000-4000 mg / L; In step S4, the internal circulation reflux ratio is set to 100%-150% to ensure the effective conversion of nitrogen in different treatment stages.

2. The integrated method of coagulation sedimentation-short-range nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonium oxidation according to claim 1, characterized in that: In step S1, the specific process of coagulation and sedimentation is as follows: Adopting high-efficiency coagulation and sedimentation technology, the sludge is coagulated and pH adjusted through the Turbo-LME high-speed sedimentation tank, and the inlet pH is adjusted to 6.5-7.5 to optimize the coagulation effect of iron salts, with a suspended solids removal rate of >90% and a COD removal rate of 20%-30%.

3. The integrated method of coagulation sedimentation-short-range nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonium oxidation according to claim 1, characterized in that: In step S2, the first stage reactor is an SBR reactor.

4. The integrated method of coagulation sedimentation-short-range nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonium oxidation according to claim 1, characterized in that: Step S3 specifically includes the following process: Inoculate anaerobic ammonium oxidation granular sludge in the second-stage reactor to ensure the biological reaction in the reactor; A phased acclimation strategy was adopted, with artificial water distribution containing low concentrations of ammonia nitrogen and nitrite nitrogen being used for adaptive acclimation, with ammonia nitrogen concentration of 50-100 mg / L and nitrite nitrogen concentration of 66-132 mg / L. The proportion of actual sewage was then increased, and Anammox activity was monitored throughout the process to ensure its stable operation. This process took 2-4 weeks. The artificial water distribution was adjusted to be completely consistent with the conditions of actual sewage by gradually introducing actual sewage in stages over 2-4 weeks. During this period, the concentrations of ammonia nitrogen and nitrite nitrogen were precisely adjusted to reflect the final sewage composition, and additional nutrients were supplemented to simulate the chemical characteristics of sewage, including acetate or propionate to simulate organic carbon content, phosphate to simulate phosphorus content, and trace elements. Sodium bicarbonate was added to adjust the alkalinity to keep the pH between 7.0-8.

0. Temperature and dissolved oxygen levels were controlled at the same time to ensure optimal Anammox activity and ensure the transition to actual sewage conditions.

5. The integrated method of coagulation sedimentation-short-range nitrification / autotrophic denitrification / heterotrophic denitrification / FEAMMOX-anaerobic ammonium oxidation according to claim 4, characterized in that: In step S3, the second stage reactor is a UASB reactor; In step S3, the particle size of the anaerobic ammonium oxidation granular sludge is between 0.5-1.0 mm.