Novel composite enhanced denitrification treatment method and system

Abstract

The invention provides a novel composite enhanced denitrification treatment method and system, and the treatment method comprises the following steps: firstly, carrying out preliminary treatment on sewage to obtain preliminarily treated sewage; then carrying out partial nitrification treatment on the primary treatment wastewater to convert partial ammonia nitrogen in the primary treatment wastewater into nitrite nitrogen to form partial nitrification wastewater, and then carrying out anaerobic ammonia oxidation treatment on the partial nitrification wastewater to generate nitrogen and anaerobic ammonia oxidation wastewater; and carrying out denitrification treatment on the anaerobic ammonia oxidation sewage to regenerate nitrogen and denitrified sewage so as to realize denitrification of the sewage. According to the method, partial nitrification, anaerobic ammonia oxidation and denitrification technologies are combined, efficient denitrification is achieved, and the total nitrogen removal rate is high.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular to a novel composite enhanced denitrification treatment method and system thereof. Background Art

[0002] With the rapid advancement of global industrialization and the continuous increase in human activities, nitrogen pollution in water bodies has become a global environmental challenge. Excessive presence of nitrogen in water bodies will not only lead to eutrophication of water bodies, trigger the proliferation of algae, consume dissolved oxygen in water, and threaten the balance of aquatic ecosystems, but may also accumulate through the food chain, posing a potential threat to human health.

[0003] Traditional denitrification processes, such as nitrification-denitrification processes, are currently the most widely used biological denitrification technologies. The nitrification process converts ammonia nitrogen into nitrates, while the denitrification process uses organic carbon sources to reduce nitrates to nitrogen gas, thereby achieving nitrogen removal. However, this process has exposed a series of problems in practical applications, such as high energy consumption, the need for a large amount of organic carbon sources as electron donors, and the generation of a large amount of residual sludge. These problems not only increase the treatment cost, but may also cause secondary pollution to the environment.

[0004] In order to overcome the limitations of traditional denitrification processes, anaerobic ammonium oxidation technology came into being. Anaerobic ammonium oxidation is a new type of biological denitrification technology that can directly convert ammonia nitrogen into nitrogen gas under anaerobic conditions using nitrite as an electron acceptor. This technology has significant advantages such as no need for an organic carbon source, low energy consumption, and low sludge production, providing a new approach to the control of nitrogen pollution. However, anaerobic ammonium oxidation technology also has some limitations, such as long start-up time, sensitivity to environmental conditions (such as temperature, pH value, dissolved oxygen concentration, etc.), and difficulty in achieving efficient denitrification alone in practical applications.

[0005] In view of the respective advantages and disadvantages of traditional denitrification processes and anaerobic ammonium oxidation technology, it is particularly important to develop new denitrification processes at present.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The first purpose of the present invention is to provide a novel composite enhanced denitrification treatment method, which combines partial nitrification, anaerobic ammonia oxidation and denitrification technologies to achieve efficient denitrification, and the total nitrogen removal rate further reduces the cost of denitrification treatment and the impact on the environment.

[0008] The second object of the present invention is to provide a novel composite enhanced denitrification treatment system for implementing the above-mentioned treatment method, which is simple to operate and highly efficient and stable.

[0009] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: A novel composite enhanced denitrification treatment method comprises the following steps: The sewage is first subjected to preliminary treatment to obtain preliminary treated sewage, and then the preliminary treated wastewater is subjected to partial nitrification treatment to convert part of the ammonia nitrogen in the preliminary treated sewage into nitrite nitrogen to form partial nitrified sewage, and then the partial nitrified sewage is subjected to anaerobic ammonia oxidation treatment to generate nitrogen gas and anaerobic ammonia oxidation sewage, and the anaerobic ammonia oxidation sewage is subjected to denitrification treatment to generate nitrogen gas and denitrified sewage again, thereby achieving denitrification of the sewage.

[0010] Preferably, the denitrified wastewater obtained after the denitrification treatment is subjected to deep treatment to ensure that the water quality meets the discharge standard.

[0011] Preferably, the preliminary treatment method is a combination of one or more of physical, chemical and biological methods.

[0012] Preferably, the anaerobic ammonium oxidation treatment is a process in which anaerobic ammonium-oxidizing bacteria react with nitrite nitrogen and ammonia nitrogen to generate nitrogen gas.

[0013] Preferably, an organic carbon source is required in the denitrification treatment to further improve the efficiency of denitrification.

[0014] The denitrification treatment method provided by the present invention is to convert part of the ammonia nitrogen in the preliminary treated sewage into nitrite nitrogen through partial nitrification, thereby providing a suitable substrate concentration for subsequent anaerobic ammonium oxidation treatment. The substrates of the anaerobic ammonium oxidation treatment process are ammonia and nitrite, but if the concentrations of the two are too high, the anaerobic ammonium oxidation process will also be inhibited; the anaerobic ammonium oxidation process utilizes the action of anaerobic ammonium-oxidizing bacteria to directly convert nitrite nitrogen and remaining ammonia nitrogen into nitrogen gas. This is an extremely efficient denitrification approach, which can greatly reduce energy consumption and sludge production compared to traditional denitrification technologies.

[0015] For the subsequent denitrification treatment, the organic carbon source is further used as an electron donor to reduce the remaining nitrite nitrogen in the sewage after anaerobic ammonium oxidation treatment to nitrogen gas, thereby achieving comprehensive removal of nitrogen in the sewage. This synergistic denitrification method of partial nitrification, anaerobic ammonium oxidation and denitrification technology has significantly improved the overall denitrification efficiency of sewage.

[0016] There is no need to add oxygen during the anaerobic ammonium oxidation process. Under anaerobic conditions, ammonia is oxidized into nitrogen gas using ammonia as the electron donor and nitrate or nitrite as the electron acceptor. This avoids the emission of large amounts of carbon dioxide in the traditional nitrification process and has a protective effect on the environment.

[0017] Although an organic carbon source is required during the denitrification process, compared with traditional denitrification methods, since most of the nitrogen content in the sewage has been removed during the previous anaerobic ammonia oxidation treatment process, the amount of organic carbon source required in the denitrification stage is greatly reduced, thereby reducing operating costs and environmental burdens.

[0018] By using the novel composite enhanced denitrification treatment method provided by the present invention, nitrogen in sewage is effectively removed, and the nitrogen content of the discharged water after denitrification treatment is significantly reduced, which is better than the national and local sewage discharge standards. This method is beneficial to protecting the water environment.

[0019] Further deep treatment, namely filtration and disinfection, can further remove pollutants such as suspended matter, organic matter and microorganisms in the discharged water to ensure that the discharged water is clear and transparent. Disinfection is the process of killing or removing pathogenic microorganisms in the water by physical or chemical methods to ensure that the sewage discharged after treatment can meet the sewage discharge standards and even the high standards for ecologically sensitive areas and reused water quality.

[0020] The present invention also provides a novel composite enhanced denitrification treatment system, comprising: Primary treatment unit, partial nitrification unit, anaerobic ammonium oxidation unit and denitrification unit; The preliminary treatment unit is used to remove large particle impurities in the sewage entering the system; The partial nitrification unit is connected to the preliminary treatment unit to reduce the risk of substrate inhibition of subsequent anaerobic ammonium oxidation; The anaerobic ammonium oxidation unit is connected to part of the nitrification unit and is used to convert nitrite nitrogen and ammonia nitrogen into nitrogen gas; The denitrification unit is connected to the anaerobic ammonium oxidation unit and is used to convert nitrate nitrogen in the sewage into nitrogen gas.

[0021] Preferably, the denitrification unit is further connected to a deep treatment unit for treating the sewage passing through the denitrification unit to ensure that the water quality of the sewage meets the discharge standard.

[0022] Preferably, the anaerobic ammonium oxidation unit uses at least one of an anaerobic fluidized bed and an anaerobic membrane bioreactor as the anaerobic ammonium oxidation reactor.

[0023] As the first direction of the novel composite enhanced denitrification treatment system of the present invention, the preliminary treatment unit can effectively remove large particle impurities in sewage, provide relatively clean water for subsequent treatment, reduce blockage and wear problems during the treatment process, and ensure the stable operation of the system. The partial nitrification unit converts part of the ammonia nitrogen into nitrite nitrogen by accurately controlling the nitrification process, avoiding the inhibitory effect of nitrate nitrogen produced by complete nitrification on the anaerobic ammonium oxidation treatment process, optimizing the substrate concentration and the efficiency of anaerobic ammonium oxidation treatment.

[0024] The anaerobic ammonium oxidation unit uses anaerobic ammonium oxidizing bacteria to directly convert nitrite nitrogen and remaining ammonia nitrogen into nitrogen gas; no external oxygen is required, which greatly saves energy, and the generated nitrogen gas is harmless to the environment, achieving efficient nitrogen removal. The denitrification unit further processes the remaining nitrate nitrogen and reduces the nitrate nitrogen to nitrogen gas by adding an organic carbon source, ensuring that the nitrogen content in the effluent is extremely low and meets strict emission standards. In addition, although the denitrification process requires an organic carbon source, this system reduces the amount of carbon source required for subsequent denitrification by optimizing part of the nitrification process, thereby reducing operating costs.

[0025] The anaerobic ammonium oxidation unit adopts a high-efficiency reactor such as an anaerobic fluidized bed or an anaerobic membrane bioreactor, which has good mass transfer effect and biomass retention capacity, ensuring the stable operation of the anaerobic ammonium oxidation process. Specifically, the units of the denitrification treatment system of the present invention are connected by pipes and valves, which are easy to adjust and control, and the treatment parameters can be flexibly adjusted according to the actual sewage inlet water quality and treatment requirements, thereby improving the adaptability and flexibility of the system.

[0026] Compared with the prior art, the present invention has the following beneficial effects: The present invention achieves efficient removal of ammonia nitrogen and nitrate nitrogen in sewage by combining three key steps: partial nitrification, anaerobic ammonium oxidation and denitrification. As a new type of biological denitrification technology, the anaerobic ammonium oxidation process can directly convert nitrite nitrogen and remaining ammonia nitrogen into nitrogen gas without the need for additional oxygen supply, thereby significantly improving the denitrification efficiency and reducing energy consumption. Compared with traditional denitrification treatment technologies, the anaerobic ammonium oxidation process in the present invention does not require oxygen, thus avoiding the energy consumption required during the treatment process; at the same time, due to the slow growth rate of anaerobic ammonium oxidizing bacteria, the amount of residual sludge produced is also small, further reducing carbon emissions during sludge treatment and disposal.

[0027] Since the anaerobic ammonium oxidation process has a low demand for organic carbon sources, although the present invention needs to add organic carbon sources to improve the denitrification efficiency during the denitrification process, it generally reduces the consumption of organic carbon sources compared to the traditional process. In addition, due to the reduction in the amount of residual sludge, the relevant costs of sludge treatment are also reduced.

[0028] The denitrification sewage can further remove suspended solids, colloids, refractory organic matter and pathogenic microorganisms in the sewage in the deep treatment unit of the present invention, ensuring that the effluent water quality meets the discharge standard, which is beneficial to protecting the water environment and human health. The denitrification treatment system of the present invention can adapt to sewage with different water quality conditions, including industrial wastewater, urban sewage, etc. The preliminary treatment unit can select one or more combinations of physical, chemical or biological methods according to actual conditions to improve the flexibility and adaptability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps. Figure 1 A schematic diagram of the overall process of a novel composite enhanced denitrification treatment method and its system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0031] The present invention provides a novel composite enhanced denitrification treatment method, see Figure 1As shown. The first step is to preliminarily treat the sewage by introducing the sewage into the screen equipment in the preliminary treatment unit to remove large particles of impurities, and then send the sewage to the grit chamber to further remove sand and fine particles in the sewage, creating more favorable conditions for subsequent treatment processes. The preliminarily treated sewage is then sent to the partial nitrification reactor in the partial nitrification unit. The key parameters such as dissolved oxygen concentration, temperature and pH value in the sewage are adjusted through the partial nitrification reactor, so that part of the ammonia nitrogen in the sewage can be converted into nitrite nitrogen. This conversion is to reduce the risk of substrate inhibition in the subsequent anaerobic ammonia oxidation step and help reduce the energy consumption of the overall system process. The partially nitrified sewage is sent to the anaerobic ammonium oxidation reactor in the anaerobic ammonium oxidation unit. In this link, the sewage that is sent is partially nitrified. In the case of subsequent continuous sewage treatment, the sewage sent to the anaerobic ammonium oxidation treatment link is sewage mixed with the liquid returned after the denitrification treatment; the mixed sewage is sent to the anaerobic ammonium oxidation reactor, where the anaerobic ammonium oxidizing bacteria will use nitrite nitrogen and ammonia nitrogen to react to generate nitrogen gas, achieving the effect of efficient denitrification. The sewage after anaerobic ammonium oxidation treatment also contains a small amount of nitrate nitrogen. The sewage containing nitrate nitrogen is sent to the denitrification reactor in the denitrification unit, and a suitable organic carbon source is added to the denitrification reactor. The organic carbon source provides energy and reducing power for the denitrifying bacteria, so that the denitrifying bacteria can complete the reduction of nitrates and convert them into nitrogen gas, further improving the overall denitrification treatment method of the present invention. After the denitrification treatment is completed, the discharged sewage is further treated in depth, that is, it is filtered and disinfected. The above is to remove suspended matter and tiny particles in the sewage to ensure that the final discharged water is clear. The above disinfection is to kill pathogenic microorganisms in the water to ensure that the water quality of the discharged water meets the relevant emission standards.

[0032] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0033] Example 1 A chemical enterprise produces high ammonia nitrogen wastewater, and the ammonia nitrogen concentration of the wastewater before denitrification treatment is 500 mg / L, and the total nitrogen concentration is 600 mg / L. The novel composite enhanced denitrification treatment method of the present invention is carried out according to the following steps: (1) First, the sewage is introduced into the screen equipment in the preliminary treatment unit to remove large particles of impurities in the sewage, and then the sewage is passed through the sedimentation tank to remove suspended matter in the sewage to prevent clogging of subsequent treatment units; (2) The sewage after preliminary treatment enters the partial nitrification reactor in the partial nitrification unit, and the dissolved oxygen concentration in the reactor is controlled to be 0.5 mg / L, the temperature to be 30°C, and the pH value to be 7.5; after the partial nitrification reaction, the ammonia nitrogen conversion rate reaches about 50%, that is, about 250 mg / L of nitrite nitrogen is generated; so that part of the ammonia nitrogen in the preliminary treated sewage is converted into nitrite nitrogen, so as to reduce the risk of substrate inhibition of subsequent anaerobic ammonia oxidation; (3) After partially nitrified sewage is mixed with denitrification return liquid, it is sent to the anaerobic ammonium oxidation reactor; the anaerobic ammonium oxidation reactor adopts the form of anaerobic fluidized bed to provide sufficient microbial attachment area and mixing effect. The temperature in the reactor is controlled at 35°C and the pH value is 7.8. After the anaerobic ammonium oxidation reaction treatment, the total nitrogen removal rate reaches more than 80%, that is, the total nitrogen concentration in the effluent is reduced to below 120 mg / L; (4) The wastewater treated by the anaerobic ammonium oxidation reactor is sent to the denitrification reactor, and methanol is added to the denitrification reactor as an organic carbon source to provide the electron donor required by the denitrifying bacteria; the COD / N ratio in the denitrification reactor is controlled to be 4 (i.e., the ratio of organic carbon source to nitrogen) to ensure the smooth progress of the denitrification reaction; after the denitrification reaction, the total nitrogen concentration is further reduced to a lower level; (5) The wastewater treated by the denitrification reactor is sent to a deep treatment unit, such as an activated carbon adsorption device, to remove suspended solids, colloids, difficult-to-degrade organic matter, and pathogenic microorganisms; after deep treatment, the wastewater quality exceeds the national emission standards and is discharged.

[0034] Example 2 The water produced by a food processing enterprise has a wastewater ammonia nitrogen concentration of 300 mg / L and a total nitrogen concentration of 400 mg / L before denitrification treatment. The novel composite enhanced denitrification treatment method of the present invention is carried out according to the following steps: (1) First, the sewage is introduced into the screen equipment in the preliminary treatment unit to remove large particles of impurities in the sewage, and then the sewage is passed through the sedimentation tank to remove suspended matter in the sewage to prevent clogging of subsequent treatment units; (2) The sewage after preliminary treatment enters the partial nitrification reactor in the partial nitrification unit, and the dissolved oxygen concentration in the reactor is controlled to be 0.8 mg / L, the temperature to be 32°C, and the pH value to be 7.2; after the partial nitrification reaction, the ammonia nitrogen conversion rate reaches about 50%, that is, about 150 mg / L of nitrite nitrogen is generated; so that part of the ammonia nitrogen in the preliminary treated sewage is converted into nitrite nitrogen, so as to reduce the risk of substrate inhibition of subsequent anaerobic ammonia oxidation; (3) After partially nitrified sewage is mixed with denitrification return liquid, it is sent to the anaerobic ammonium oxidation reactor; the anaerobic ammonium oxidation reactor adopts the form of anaerobic fluidized bed to provide sufficient microbial attachment area and mixing effect. The temperature in the reactor is controlled at 37°C and the pH value is 7.5. After the anaerobic ammonium oxidation reaction treatment, the total nitrogen removal rate reaches more than 75%, that is, the total nitrogen concentration in the effluent is reduced to below 100 mg / L; (4) The wastewater treated by the anaerobic ammonium oxidation reactor is sent to the denitrification reactor, and glucose is added to the denitrification reactor as an organic carbon source to provide the electron donor required by the denitrifying bacteria; the COD / N ratio in the denitrification reactor is controlled to be 4 (i.e., the ratio of organic carbon source to nitrogen) to ensure the smooth progress of the denitrification reaction; after the denitrification reaction, the total nitrogen concentration is further reduced to a lower level; (5) The wastewater treated by the denitrification reactor is sent to a deep treatment unit, such as an activated carbon adsorption device, to remove suspended solids, colloids, difficult-to-degrade organic matter, and pathogenic microorganisms; after deep treatment, the wastewater quality exceeds the national emission standards and is discharged.

[0035] In summary, the novel composite enhanced denitrification treatment method of the present invention performs a series of treatment steps for high-ammonia nitrogen-containing wastewater from different sources to achieve efficient denitrification. The present invention successfully achieves efficient denitrification treatment of wastewater by comprehensively applying partial nitrification, anaerobic ammonia oxidation and denitrification technologies, and significantly improves the total nitrogen removal rate; among them, the use of anaerobic ammonia oxidation technology does not require the addition of additional organic carbon sources, which not only effectively reduces the treatment cost, but also reduces the burden on the environment; at the same time, the partial nitrification process pre-converts part of the ammonia nitrogen into nitrite nitrogen, reducing the risk of substrate inhibition during the anaerobic ammonia oxidation process and enhancing the stability of the entire system. The subsequent denitrification step further removes residual nitrate nitrogen, ensuring that the effluent water quality meets national emission standards; therefore, this method is particularly suitable for the treatment of high-ammonia nitrogen wastewater.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A novel composite enhanced denitrification treatment method, characterized in that: The steps include: The sewage is first subjected to preliminary treatment to obtain preliminary treated sewage, and then the preliminary treated wastewater is subjected to partial nitrification treatment to convert part of the ammonia nitrogen in the preliminary treated sewage into nitrite nitrogen to form partial nitrified sewage, and then the partial nitrified sewage is subjected to anaerobic ammonia oxidation treatment to generate nitrogen gas and anaerobic ammonia oxidation sewage, and the anaerobic ammonia oxidation sewage is subjected to denitrification treatment to generate nitrogen gas and denitrified sewage again, thereby achieving denitrification of the sewage.

2. The novel composite enhanced denitrification treatment method according to claim 1, characterized in that: The denitrified wastewater obtained after the denitrification treatment is subjected to deep treatment to ensure that the water quality meets the discharge standard.

3. The novel composite enhanced denitrification treatment method according to claim 1, characterized in that: The preliminary treatment method is one or a combination of physical method, chemical method and biological method.

4. The novel composite enhanced denitrification treatment method according to claim 1, characterized in that: The anaerobic ammonium oxidation treatment is a process in which anaerobic ammonium oxidizing bacteria react with nitrite nitrogen and ammonia nitrogen to generate nitrogen gas.

5. The novel composite enhanced denitrification treatment method according to claim 1, characterized in that: An organic carbon source needs to be used in the denitrification treatment to further improve the efficiency of denitrification.

6. A novel composite enhanced denitrification treatment system according to any one of claims 1 to 7, characterized in that: include: Primary treatment unit, partial nitrification unit, anaerobic ammonium oxidation unit and denitrification unit; The preliminary treatment unit is used to remove large particle impurities in the sewage entering the system; The partial nitrification unit is connected to the preliminary treatment unit to reduce the risk of substrate inhibition of subsequent anaerobic ammonium oxidation; The anaerobic ammonium oxidation unit is connected to part of the nitrification unit and is used to convert nitrite nitrogen and ammonia nitrogen into nitrogen gas; The denitrification unit is connected to the anaerobic ammonium oxidation unit and is used to convert nitrate nitrogen in the sewage into nitrogen gas.

7. The novel composite enhanced denitrification treatment system according to claim 6 is characterized in that: The denitrification unit is also connected to a deep treatment unit for treating the sewage that has passed through the denitrification unit to ensure that the water quality of the sewage meets the discharge standard.

8. The novel composite enhanced denitrification treatment system according to claim 6 is characterized in that: The anaerobic ammonium oxidation unit adopts at least one of an anaerobic fluidized bed and an anaerobic membrane bioreactor as an anaerobic ammonium oxidation reactor.

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