A method for denitrification and dephosphorization of urban sewage by coupling of side-stream pure biofilm anoxic denitrification and anaerobic ammonia oxidation to reinforce A2 / O process

Abstract

The application discloses a kind of side flow pure biofilm anoxic denitrification coupling anaerobic ammonia oxidation enhanced municipal wastewater A2 / O process denitrification and phosphorus removal method, it is related to wastewater treatment technical field, the method is realized based on the system consisting of main flow area and side flow area, the system further includes: side flow pure biofilm treatment subsystem, be located in side flow area;Primary sedimentation tank and secondary sedimentation tank, be located in main flow area, the effluent end of primary sedimentation tank and secondary sedimentation tank is connected with side flow pure biofilm treatment subsystem, part of effluent in primary sedimentation tank and secondary sedimentation tank enters side flow pure biofilm treatment subsystem;Anaerobic zone, be located in main flow area, side flow pure biofilm treatment subsystem drains water to anaerobic zone by backwater pipe;The method from two sedimentation tanks part of effluent enters into side flow pure biofilm treatment subsystem, such nitrate nitrogen utilizes raw water carbon source and carries out heterotrophic denitrification denitrification, simultaneously, using ammonia nitrogen and nitrite nitrogen carries out anaerobic ammonia oxidation denitrification.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of sewage treatment, and more particularly relates to a method for enhancing denitrification and phosphorus removal of municipal sewage A2 / O process by using a side-flow pure biofilm anoxic denitrification coupled with anaerobic ammonia oxidation. BACKGROUND

[0002] The standard discharge of municipal sewage treatment plants is the focus of attention in recent years, especially the standard discharge and control of effluent nitrogen and phosphorus are increasingly strict. In recent years, many sewage treatment plants still face the situation of upgrading and reconstruction due to the failure to meet the standard discharge of total nitrogen. The carbon-nitrogen ratio of the influent of these sewage treatment plants is relatively low, and the use of traditional nitrification-denitrification technology limits the denitrification efficiency of the process. In order to meet the increasingly strict discharge requirements, the method of adding external carbon source is widely used to enhance denitrification, but the cost of adding carbon source is very high. On the other hand, a large amount of aeration is required for nitrification, and the current situation of energy saving and consumption reduction of the entire sewage treatment plant is severe. Therefore, seeking a new low-consumption and high-efficiency sewage denitrification technology is a difficult problem in the current environmental field.

[0003] Anaerobic ammonia oxidation (Anammox) is a new biological technology, and its discovery is regarded as a sustainable method for denitrification from municipal sewage. Anaerobic ammonia oxidation bacteria can oxidize ammonia nitrogen (NH4 + ) to nitrogen (N2) under anaerobic conditions, and its advantage is that it does not require dissolved oxygen and organic carbon. At present, there are more than one hundred projects in the world using anaerobic ammonia oxidation technology to treat high ammonia wastewater, including sludge digestion supernatant, landfill leachate and aquaculture wastewater. In the past decade, more and more application researches on anaerobic ammonia oxidation technology in the treatment of low ammonia wastewater have been carried out, which highlights the great application potential of this technology in municipal sewage treatment, but the solution of the bottleneck problem still needs to be verified by research and application, and the application of this technology to the mainstream area will maximize the energy consumption of wastewater treatment plants, which is beneficial to the realization of carbon emission reduction target in the environmental protection field.

[0004] In recent years, the short-cut denitrification-anaerobic ammonia oxidation process (PD / A) has attracted widespread attention in the field of municipal sewage treatment. In fact, anaerobic ammonia oxidation bacteria can reduce nitrate (NO3 - ) to nitrite (NO2 - ), and then convert NO2 - and NH4 + to N2. Studies have shown that the PD / A process is efficient in denitrification, low in carbon consumption, and low in residual sludge production. At present, positive progress has been made in the exploration of regulation strategies for short-cut denitrification coupled with anaerobic ammonia oxidation technology, and recent studies have shown that reducing the suspended sludge concentration may help in the reduction of NO3 - during the process of NO2 -The production of NO2- and N2O suggests that the enhanced anoxic biofilm metabolic process is a potential key regulatory factor. The effluent total nitrogen concentration of the short-cut denitrification-anammox process is significantly lower than that of the traditional nitrification-denitrification process, which has practical research significance and engineering application prospects. SUMMARY

[0005] The present application aims at the deficiencies in the prior art, and provides a method for enhancing the denitrification and phosphorus removal of urban sewage A2 / O process by using a side flow pure biofilm anoxic denitrification coupled with anammox, which is characterized in that a part of the effluent from the primary sedimentation tank and the secondary sedimentation tank is introduced into the side flow pure biofilm treatment subsystem, so that the nitrate nitrogen uses the carbon source in the raw water for heterotrophic denitrification, and at the same time, the short-cut denitrification occurs in the low C / N ratio environment to produce nitrite nitrogen, so that the anammox bacteria on the carrier biofilm use the ammonia nitrogen and the nitrite nitrogen for anammox denitrification.

[0006] To achieve the above-mentioned purpose, the present application provides a method for enhancing the denitrification and phosphorus removal of urban sewage A2 / O process by using a side flow pure biofilm anoxic denitrification coupled with anammox, which is realized based on a system composed of a main flow zone and a side flow zone, and the system further comprises:

[0007] a side flow pure biofilm treatment subsystem arranged in the side flow zone;

[0008] a primary sedimentation tank and a secondary sedimentation tank both arranged in the main flow zone, and the effluent ends of the primary sedimentation tank and the secondary sedimentation tank are connected with the side flow pure biofilm treatment subsystem, and a part of the effluent in the primary sedimentation tank and the secondary sedimentation tank is introduced into the side flow pure biofilm treatment subsystem;

[0009] an anaerobic zone arranged in the main flow zone, and the side flow pure biofilm treatment subsystem is connected with the anaerobic zone through a backwater pipe.

[0010] Optionally, the side flow pure biofilm treatment subsystem is provided with a carrier biofilm, and the filling ratio of the carrier biofilm is less than 66.7%.

[0011] Optionally, the main flow zone further comprises an anoxic zone and an aerobic zone, the bottom of the secondary sedimentation tank is connected with the anaerobic zone through a sludge return pipe, the end of the aerobic zone is connected with the anoxic zone through a nitrification liquid return pipe, and the effluent end of the secondary sedimentation tank is provided with a drainage pipe.

[0012] Optionally, the drainage pipe is connected with the side flow pure biofilm treatment subsystem through an effluent branch pipe.

[0013] The present application provides a method for enhancing the denitrification and phosphorus removal of urban sewage A2 / O process by using a side flow pure biofilm anoxic denitrification coupled with anammox, which has the following beneficial effects:

[0014] 1、the method can save aeration quantity significantly, traditional urban sewage treatment plant based on activated sludge method nitrification denitrification process conversion 1gNH4 + -N theoretically consumes 4.57gO2;The system side stream treatment can complete part of anaerobic ammonia oxidation autotrophic denitrification, so a certain proportion of ammonia nitrogen does not need to be converted into nitrate nitrogen by aeration in the main flow area process, and theoretically consumes between 2.29-4.57gO2, which can effectively reduce the aeration energy consumption of the sewage treatment plant;

[0015] 2、the method can save carbon source dosage, traditional nitrification denitrification process removes 1gNO3 - -N theoretically requires 2.86gCOD;The side stream treatment process of the system realizes part of anaerobic ammonia oxidation autotrophic denitrification, which leads to a certain proportion of nitrate nitrogen being converted into nitrogen without carbon source, and the conversion of nitrate nitrogen into nitrogen during the reduction process does not require carbon source, and the corresponding carbon source saved can be further used for removing total nitrogen in the main flow area, so the system removes 1gNH4 + -N theoretically can provide a lower amount of carbon source, when the organic matter in the raw water is less, the carbon source dosage is significantly saved compared to the traditional nitrification denitrification process, and if the organic matter in the raw water reaches a certain range, even no carbon source needs to be added;

[0016] 3、the method can reduce the residual sludge yield, the reaction process of the system is part of autotrophic denitrification, the sludge yield is effectively reduced, which is beneficial to reduce the sludge disposal cost;

[0017] 4、the autotrophic denitrification in the side flow area of the system is strong in robustness, the system combines short-cut denitrification based on side flow with part of anaerobic ammonia oxidation process, the carrier biofilm effectively retains anaerobic ammonia oxidation bacteria, and has good impact resistance, and the process has strong robustness;

[0018] 5、the autotrophic denitrification in the main flow area of the system is improved, the side flow area can efficiently realize anaerobic ammonia oxidation denitrification, the biofilm will continuously fall off in the metabolic process, and the fallen biofilm will strengthen the proportion of autotrophic denitrification after entering the main flow area, thereby improving the autotrophic denitrification capacity of the main flow area;

[0019] 6、the system has strong engineering adaptability, can be upgraded and modified simply in the built water plant, the process is simple and flexible, the system management and operation are easy to implement, and is easy to popularize and apply;For a newly built sewage treatment plant, compared with the traditional nitrification denitrification process, the same denitrification load can be achieved by arranging the process simply.

[0020] Other features and advantages of the present application will be described in detail in the following specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0021] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference characters refer to like parts throughout the figures, and in which:

[0022] Figure 1 Fig. 1 shows a structural schematic diagram of a system for denitrification and phosphorus removal of municipal wastewater by a side-stream pure biofilm anoxic denitrification coupled with anaerobic ammonia oxidation enhanced A2 / O process according to an embodiment of the present application.

[0023] BRIEF DESCRIPTION OF DRAWINGS

[0024] 1, primary sedimentation tank; 2, primary sedimentation tank effluent pipe; 3, anaerobic zone; 4, anoxic zone; 5, aerobic zone; 6, secondary sedimentation tank; 7, nitrification liquid return pipe; 8, sludge return pipe; 9, excess sludge discharge pipe; 10, drainage pipe; 11, effluent branch pipe; 12, primary sedimentation tank effluent branch; 13, side-stream pure biofilm treatment subsystem; 14, carrier biofilm; 15, backwater pipe. DETAILED DESCRIPTION

[0025] Preferred embodiments of the present application will be described in greater detail below. Although the following describes preferred embodiments of the present application, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present application will be thorough and complete, and will fully convey the scope of the present application to those skilled in the art.

[0026] The present application provides a method for denitrification and phosphorus removal of municipal wastewater by a side-stream pure biofilm anoxic denitrification coupled with anaerobic ammonia oxidation enhanced A2 / O process, which is realized based on a system composed of a main stream zone and a side stream zone, and the system further comprises:

[0027] a side-stream pure biofilm treatment subsystem, which is arranged in the side stream zone;

[0028] a primary sedimentation tank and a secondary sedimentation tank, which are both arranged in the main stream zone, and the effluent ends of the primary sedimentation tank and the secondary sedimentation tank are connected to the side-stream pure biofilm treatment subsystem, and a part of the effluent of the primary sedimentation tank and the secondary sedimentation tank enters the side-stream pure biofilm treatment subsystem;

[0029] an anaerobic zone, which is arranged in the main stream zone, and the side-stream pure biofilm treatment subsystem discharges water to the anaerobic zone through a backwater pipe.

[0030] Specifically, the system has a primary sedimentation tank and a secondary sedimentation tank, and the part of the effluent of the secondary sedimentation tank is mixed together to provide a reaction substrate for short-cut denitrification coupled with anaerobic ammonia oxidation, and the effluent of the side-stream pure biofilm treatment subsystem is sent to the anaerobic zone through a backwater pipe after reaction, and the anaerobic phosphorus release reaction is carried out in the anaerobic zone: the phosphorus accumulating organisms utilize the volatile fatty acids (VFAs) in the raw water to synthesize the internal carbon source PHAs to reduce the C / N ratio, and release the phosphorus to the extracellular; the nitrate nitrogen can also utilize the carbon source in the raw water for heterotrophic denitrification, that is, the process of reducing the nitrate nitrogen to nitrogen gas.

[0031] Optionally, the side-stream pure biofilm treatment subsystem is provided with a carrier biofilm, and a filling ratio of the carrier biofilm is less than 66.7%.

[0032] Specifically, the side-stream pure biofilm treatment subsystem needs to be provided with a carrier that is easy to form a biofilm, to provide an anoxic microenvironment for denitrifying functional microorganisms, to facilitate the growth of denitrifying bacteria and anaerobic ammonia oxidation bacteria; the biofilm filling ratio of the side-stream pure biofilm treatment subsystem is less than 66.7%, and a fluidized mode is adopted; the carrier can be an anaerobic ammonia oxidation carrier that has been cultivated, a denitrification carrier that has been cultivated, or a blank filler carrier.

[0033] Optionally, the main stream zone further comprises an anoxic zone and an aerobic zone, the bottom of the secondary sedimentation tank is connected to the anaerobic zone through a sludge return pipe, the end of the aerobic zone is connected to the anoxic zone through a nitrification liquid return pipe, and the effluent end of the secondary sedimentation tank is provided with a drain pipe.

[0034] Specifically, the main stream zone is not limited to the A 2 / O process, and can be a similar or improved plug-flow process, such as A / O, multi-stage A / O, AOA, UCT process, etc. The return pipe of the sludge return pipe is controlled at 50%-100%, the return ratio of the nitrification liquid return pipe is controlled at 75%-200%, the total hydraulic retention time of the main stream zone is designed to be 8-17 hours, the hydraulic retention time of the aerobic zone is 5-9 hours, and the dissolved oxygen at the end of the aerobic zone is controlled at 1-3 mg / L to ensure the completion of the nitrification reaction.

[0035] Optionally, the drain pipe is connected to the side-stream pure biofilm treatment subsystem through an effluent branch pipe.

[0036] Specifically, in the system, the wastewater containing ammonia nitrogen after the primary sedimentation tank treatment enters the anaerobic zone, the ammonia nitrogen concentration of the influent is 15-80 mg / L, the carbon-nitrogen ratio is between 1.5-6, at the same time, the front end of the anaerobic zone also has sludge returned by the sludge return pipe and effluent returned by the backwater pipe, and the anaerobic phosphorus release reaction is carried out in the anaerobic zone: the phosphorus accumulating organisms use the volatile fatty acids (VFAs) in the raw water to synthesize the internal carbon source PHAs to reduce the C / N ratio, and release the phosphorus to the extracellular; the nitrate nitrogen can also use the carbon source in the raw water for heterotrophic denitrification, i.e. the process of reducing the nitrate nitrogen to nitrogen gas.

[0037] The wastewater treated by the anaerobic zone enters the anoxic zone, and the nitrated liquid returned from the end of the aerobic zone, the return ratio of the nitrated liquid is 75%-200%, and the nitrated nitrogen is also contained, the concentration of the nitrated nitrogen is 5-15 mg / L, so that the nitrated nitrogen uses the carbon source in the wastewater for heterotrophic denitrification in the anoxic zone, i.e. the process of reducing the nitrated nitrogen to nitrogen gas.

[0038] The wastewater treated by the anaerobic zone enters the anoxic zone, and the nitrated liquid returned from the end of the aerobic zone, the return ratio of the nitrated liquid is 75%-200%, and the nitrated nitrogen is also contained, the concentration of the nitrated nitrogen is 5-15 mg / L, so that the nitrated nitrogen uses the carbon source in the wastewater for heterotrophic denitrification in the anoxic zone, i.e. the process of reducing the nitrated nitrogen to nitrogen gas.

[0039] The wastewater treated by the anaerobic zone enters the anoxic zone, and the nitrated liquid returned from the end of the aerobic zone, the return ratio of the nitrated liquid is 75%-200%, and the nitrated nitrogen is also contained, the concentration of the nitrated nitrogen is 5-15 mg / L, so that the nitrated nitrogen uses the carbon source in the wastewater for heterotrophic denitrification in the anoxic zone, i.e. the process of reducing the nitrated nitrogen to nitrogen gas.

[0040] The side flow pure biofilm treatment subsystem is a continuous flow process, the influent of which is from a part of effluent of the primary sedimentation tank and the secondary sedimentation tank, and the nitrate nitrogen is denitrified by heterotrophic denitrification using the carbon source in raw water, that is, the process of reducing the nitrate nitrogen to nitrogen; meanwhile, the short-cut denitrification occurs in the low C / N ratio environment to produce nitrite nitrogen, and the anaerobic ammonia oxidation bacteria use the ammonia nitrogen and the nitrite nitrogen for anaerobic ammonia oxidation denitrification on the carrier in the side flow pure biofilm treatment subsystem. The water treated by the side flow pure biofilm treatment subsystem is all returned to the front end of the anaerobic zone, and with the growth and enrichment of the biofilm, a part of the biofilm will naturally fall off, and the anaerobic ammonia oxidation bacteria contained in the fallen biofilm can be supplemented to the main flow process, so as to strengthen the autotrophic biological denitrification in the main flow zone, and thus be beneficial to the treatment of the low carbon-nitrogen ratio sewage.

[0041] Embodiment

[0042] As shown in Figure 1 The present application provides a method for strengthening the denitrification and phosphorus removal of urban sewage A2 / O process by side flow pure biofilm anoxic denitrification coupled with anaerobic ammonia oxidation, which is realized based on a system composed of a main flow zone and a side flow zone, and the system further comprises:

[0043] A side flow pure biofilm treatment subsystem 13 is arranged in the side flow zone.

[0044] A primary sedimentation tank 1 and a secondary sedimentation tank 6 are arranged in the main flow zone, and the effluent end of the primary sedimentation tank 1 and the secondary sedimentation tank 6 is connected with the side flow pure biofilm treatment subsystem 13, and a part of the effluent in the primary sedimentation tank 1 and the secondary sedimentation tank 6 enters the side flow pure biofilm treatment subsystem 13.

[0045] An anaerobic zone 3 is arranged in the main flow zone, and the side flow pure biofilm treatment subsystem 13 discharges water to the anaerobic zone 3 through a backwater pipe 15.

[0046] In this embodiment, the side flow pure biofilm treatment subsystem 13 is provided with a carrier biofilm 14, and the filling ratio of the carrier biofilm 14 is less than 66.7%.

[0047] In this embodiment, the main flow zone further comprises an anoxic zone 4 and an aerobic zone 5, the bottom of the secondary sedimentation tank 6 is connected with the anaerobic zone 3 through a sludge return pipe 8, the end of the aerobic zone is connected with the anoxic zone 4 through a nitrification liquid return pipe 7, and the effluent end of the secondary sedimentation tank 6 is provided with a drainage pipe 10.

[0048] In this embodiment, the drainage pipe 10 is connected with the side flow pure biofilm treatment subsystem 13 through an effluent branch pipe 11.

[0049] In summary, the method for denitrification and phosphorus removal of the A2 / O process of municipal wastewater by the side flow pure biofilm anoxic denitrification coupled with anaerobic ammonia oxidation strengthens the denitrification of the wastewater with the sludge concentration of 1600-6000 mg / L, which is sent into the anaerobic zone 3, the anoxic zone 4 and the aerobic zone 5 in turn, so as to provide a basic environment for the denitrification functional microorganism, which is beneficial to the growth of denitrifying bacteria, nitrifying bacteria and phosphorus accumulating bacteria; in addition, the side flow pure biofilm treatment subsystem 13 is inoculated with the anaerobic ammonia oxidation biofilm, and the polyethylene filler biofilm with a diameter of 25 mm can be used, and when the inoculation condition is not met, the blank biofilm carrier can be added, and the biofilm is gradually formed along with the operation of the system. During the operation of the system, the return ratio of the sludge return pipe 8 is controlled at 50%-125%, and the dissolved oxygen concentration in the aerobic zone is controlled at 1.0-3.0 mg / L, so as to ensure the completion of nitrification; the effluent branch pipe 11 introduces part of the effluent in the secondary sedimentation tank 6 into the side flow pure biofilm treatment subsystem 13, and the primary sedimentation tank effluent branch 12 also introduces part of the effluent in the primary sedimentation tank 1 into the side flow pure biofilm treatment subsystem 13, the mixing flow ratio is flexibly adjusted according to the water quality of the two types of influent, the control of the mixed water quality is realized, the COD / NO3 - -N is controlled at 2.0-5.0, the NO3 - -N / NH4 + -N is controlled at 1.0-3.0; the hydraulic retention time of the side flow pure biofilm treatment subsystem 13 is controlled at 2-15 h; after the stable operation of the whole system, when the influent NH4 + -N concentration is 40 mg / L and the influent COD / TN is 4, the effluent COD concentration is 20-50 mg / L, the NH4 + -N concentration is 0-1 mg / L, the NO3 - -N concentration is 4-8 mg / L, and the TN concentration is 5-10 mg / L.

[0050] The above has described the embodiments of the present application, and the above description is exemplary, is not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for nitrogen and phosphorus removal in an anoxic denitrification coupled with anaerobic ammonium oxidation in a side-flow pure biofilm process for enhanced A2 / O treatment of urban wastewater, characterized in that... This method is based on a system consisting of a main flow region and a side flow region, which also includes: A side-flow pure biofilm treatment subsystem (13) is installed in the side-flow zone; The primary sedimentation tank (1) and the secondary sedimentation tank (6) are both located in the main flow zone. The effluent ends of the primary sedimentation tank (1) and the secondary sedimentation tank (6) are connected to the side flow pure biofilm treatment subsystem (13). A portion of the effluent from the primary sedimentation tank (1) and the secondary sedimentation tank (6) enters the side flow pure biofilm treatment subsystem (13). The anaerobic zone (3) is located within the main flow zone, and the side flow pure biofilm treatment subsystem (13) discharges water only into the anaerobic zone (3) through the return water pipe (15). The side-flow pure biofilm treatment subsystem (13) is equipped with a carrier biofilm (14), and the filling ratio of the carrier biofilm (14) is less than 66.7%. In the side-flow pure biofilm treatment subsystem, nitrate nitrogen is removed by heterotrophic denitrification using carbon sources in the raw water; at the same time, short-cut denitrification occurs under a low C / N ratio environment to produce nitrite nitrogen. On the carrier within this side-flow pure biofilm treatment subsystem, anaerobic ammonia-oxidizing bacteria use ammonia nitrogen and nitrite nitrogen for anaerobic ammonia oxidation denitrification.

2. The method for nitrogen and phosphorus removal in the A2 / O process of urban wastewater treatment using a side-flow pure biofilm anoxic denitrification coupled with anaerobic ammonia oxidation as described in claim 1, characterized in that... The main zone also includes an anoxic zone (4) and an aerobic zone (5). The bottom of the secondary sedimentation tank (6) is connected to the anaerobic zone (3) through a sludge return pipe (8). The end of the aerobic zone is connected to the anoxic zone (4) through a nitrification liquid return pipe (7). The outlet end of the secondary sedimentation tank (6) is equipped with a drain pipe (10).

3. The method for nitrogen and phosphorus removal in the A2 / O process of urban wastewater treatment using a side-flow pure biofilm anoxic denitrification coupled with anaerobic ammonia oxidation as described in claim 2, is characterized in that... The drain pipe (10) is connected to the side flow pure biofilm treatment subsystem (13) via the outlet branch pipe (11).

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