A method and device for highly efficient nitrogen removal by short-cut nitrification-short-cut denitrification double-coupled anaerobic ammonium oxidation

Abstract

A method and device for highly efficient nitrogen removal by coupling short-cut nitrification, short-cut denitrification and anaerobic ammonium oxidation belong to the field of sewage treatment. Domestic sewage enters the first SBR to remove most of the organic matter, and the effluent enters the second SBR for anaerobic-aerobic-anaerobic operation. The second SBR discharges flocculent sludge every other cycle to wash out nitrifying bacteria and uses the sludge strengthened by the surplus sludge input into the first SBR as the source of short-cut nitrification sludge. AOB grows preferentially over NOB, enabling the gradual recovery of short-cut nitrification in the second SBR. Moreover, the heterotrophic denitrifying bacteria added with the sludge can reduce nitrate nitrogen to nitrite nitrogen in the anaerobic section. The two nitrite nitrogen supply pathways strengthen the mainstream anaerobic ammonium oxidation, realizing the coupling of short-cut nitrification, short-cut denitrification and anaerobic ammonium oxidation and achieving deep nitrogen removal. This method is instructive for the startup, maintenance and recovery of short-cut nitrification, saves energy consumption and greatly improves the nitrogen removal efficiency of urban sewage.

Description

Technical Field

[0001] The present invention relates to a method and device for highly efficient nitrogen removal by short-cut nitrification-short-cut denitrification double-coupled anaerobic ammonium oxidation, belonging to the field of urban sewage treatment. This method is applicable to the deep nitrogen removal of low C / N urban domestic sewage. Background Art

[0002] With the continuous prosperity of social and urban development and the continuous enrichment of human life, a large amount of pollutants are generated. These pollutants are discharged into natural water bodies in large quantities, causing serious water pollution in rivers, lakes and seas. The problem of water eutrophication caused by nitrogen and phosphorus substances is particularly serious. It is urgent to efficiently treat urban sewage. And because the sewage treatment cost is relatively high, it is of great significance to develop an energy-saving and efficient biological treatment technology.

[0003] The nitrogen removal process commonly used in sewage treatment plants in China is biological nitrification-denitrification. However, with the increasingly serious water pollution problem and the stricter discharge standards, the traditional nitrification-denitrification exposes many problems, such as high energy consumption, high cost, large sludge production, and easy generation of greenhouse gases. The anaerobic ammonium oxidation process is a biological autotrophic nitrogen removal technology that has received much attention in recent years and has significant economic and environmental benefits, and has been widely used in the field of sewage treatment. Among many nitrogen removal technologies, the short-cut nitrification coupled with anaerobic ammonium oxidation process has received extensive attention. Short-cut nitrification can be an important source of providing nitrite, but one of the main bottlenecks faced by this process is the stable maintenance of short-cut nitrification, that is, continuously obtaining nitrite. The traditional methods for realizing short-cut nitrification include free ammonia treatment, free nitrous acid treatment, hydroxylamine, dissolved oxygen control, etc. The principle is to inhibit the growth of NOB and continuously wash out NOB, so that AOB grows dominantly and provides substrates for anaerobic ammonium oxidation. However, these methods also face defects such as high investment cost, complex processes, and difficulty in maintaining a single treatment effect for a long time. Some studies use sludge strengthening technology to control the sludge age and continuously add short-cut nitrification sludge to achieve stable short-cut nitrification coupled with anaerobic ammonium oxidation. However, obtaining short-cut nitrification sludge faces the problem of high cost and is difficult to obtain on a large scale. Therefore, this method cannot be popularized.

[0004] The EBPR-PNA process based on mainstream anaerobic ammonium oxidation is a typical two-sludge system, which solves the contradiction between carbon source and sludge age in the processes of nitrogen removal and phosphorus removal. Among them, EBPR removes organic matter and recovers bioenergy, providing good influent for PNA and reducing the adverse impact of organic matter on anaerobic ammonium oxidation. PNA is a completely autotrophic nitrogen removal process. Shortcut nitrification provides stable nitrite accumulation for anaerobic ammonium oxidation. Based on previous studies, the present invention uses the excess sludge with extremely low nitrifying bacteria content in the EBPR system for sludge enhanced addition to the PNA system and cultivates AOB as the source of shortcut nitrifying sludge, constructs a new type of A-B process, and realizes the coupling of shortcut nitrification - shortcut denitrification and anaerobic ammonium oxidation. Only the existing sewage treatment equipment is used, without additional chemical agents and equipment investment, and the operation is simple and the cost is low. It has guiding significance for the startup, stable operation, recovery after damage of shortcut nitrification and the mainstream anaerobic ammonium oxidation process of municipal sewage. Summary of the Invention

[0005] Aiming at the problems such as the difficulty in starting up and maintaining shortcut nitrification and the difficulty in deep nitrogen removal in sewage treatment technology, the present invention provides a method and device for highly efficient nitrogen removal by coupling shortcut nitrification - shortcut denitrification and anaerobic ammonium oxidation. Domestic sewage enters the first SBR and undergoes anaerobic-aerobic operation to remove most of the organic matter. The effluent enters the second SBR and undergoes anaerobic-aerobic-anaerobic operation. Flocculent sludge is discharged every two cycles to wash out nitrifying bacteria, and the excess sludge used for sludge enhanced addition to the first SBR is used as the source of shortcut nitrifying sludge. AOB preferentially grows over NOB, gradually restoring shortcut nitrification in the second SBR. The added heterotrophic denitrifying bacteria reduce nitrate nitrogen to nitrite nitrogen in the anoxic section and supply it to anaerobic ammonium oxidation. Through the above process, shortcut nitrification - shortcut denitrification coupling anaerobic ammonium oxidation is achieved in the second SBR, achieving the purpose of deep nitrogen removal.

[0006] This solution is achieved through the following technical solutions:

[0007] (I) Start-up and operation of the first SBR: The first SBR (1) is inoculated with fully nitrified sludge, and the sludge concentration is maintained at 2000 - 3000 mg / L. The start-up and operation of the first SBR (1) include the following two stages: Stage 1, the influent is domestic sewage, and the influent volume is 50% of the effective volume of the reactor. It operates in an anaerobic-aerobic mode, with 4 cycles per day. After anaerobic stirring for 30 - 60 min, aeration is carried out. The aerobic stirring time is 30 - 60 min, sedimentation is 30 min, and drainage is 5 min. The DO concentration is monitored in real time and online through the first DO probe (1.4), and the DO concentration in the aerobic section is maintained at 0.5 - 2.0 mg / L. Before the end of each cycle reaction, the SRT is controlled at 5 - 10 days by sludge discharge. When the effluent COD concentration is less than 100 mg / L, the phosphate concentration is less than 0.5 mg / L, and the difference in ammonia nitrogen concentration between the influent and effluent is less than 5 mg / L and remains for more than 3 consecutive days, it is considered that the start-up of the first SBR (1) is successful.

[0008] Stage 2, the influent is domestic sewage, and the influent volume is 50% of the effective volume of the reactor. It operates in an anaerobic-aerobic mode, with 4 cycles per day. After anaerobic stirring for 30 - 60 min, aeration is carried out. The aerobic stirring time is 30 - 60 min, sedimentation is 30 min, and drainage is 5 min. The DO concentration is monitored in real time and online through the first DO probe (1.4), and the DO concentration in the aerobic section is maintained at 0.5 - 2.0 mg / L. Before the end of each cycle reaction, the SRT is controlled at 5 - 10 days by sludge discharge. The effluent COD concentration is less than 100 mg / L, the phosphate concentration is less than 0.5 mg / L, and the difference in ammonia nitrogen concentration between the influent and effluent is less than 5 mg / L and can be stably maintained for more than 100 days.

[0009] (II) Start-up and operation of the second SBR: The second SBR (2) is inoculated with fully nitrified flocculent sludge and anaerobic ammonium oxidation granular sludge, and the sludge concentration is maintained at 1800 - 2000 mg / L. The operation of the second SBR (2) includes the following three stages.

[0010] Phase 1: Complete nitrification, without anaerobic ammonia oxidation. It operates in 2 cycles per day, and the specific operation is as follows: The influent is the effluent of the first SBR (1), which is pumped from the intermediate water tank (1.12) into the second SBR (2) through the second peristaltic pump (1.13), and the influent volume is 50% of the effective volume of the reactor. After the influent ends, anaerobic stirring is carried out, and the anaerobic stirring time is set to 0.5 h. The second air pump (2.9) is turned on to supply oxygen to the third SBR (2), and the DO concentration is monitored in real time through the second DO probe (2.3) to maintain the DO concentration at 2.0 - 3.0 mg / L, and the aeration time is set to 1 - 1.5 h. Control the ammonia nitrogen concentration at the end of aeration to be 10.0 - 15.0 mg / L. The anoxic stirring time is set to 4.5 - 6.5 h, sedimentation for 30 min, and drainage for 5 min. When the NAR in the aerobic section is less than 5%, the difference between the ammonia nitrogen concentration and the nitrate nitrogen concentration at the initial and final stages of the anoxic section is less than 3 mg / L, the effluent COD concentration is 40.0 - 50.0 mg / L and remains above for more than 3 consecutive days, it is considered that the second SBR (2) starts successfully and Phase 1 ends.

[0011] In Stage 2, sludge discharge and sludge feeding are carried out simultaneously. Nitrification is inhibited, and shortcut denitrification coupled with anaerobic ammonium oxidation occurs. It operates 2 cycles per day. The specific operation is as follows: Sludge is discharged every other cycle. The volume ratio of the sludge discharged before sedimentation is 5%-8% and enters the sludge discharge bucket (2.12). The flocculent sludge is washed out through a 70-mesh sieve, and the granular sludge is retained and put back into the second SBR (2). Sludge is fed every other cycle. Before the start of water inlet, the excess sludge of the first SBR (1) with a volume ratio of 5%-8% is washed and pumped into the second SBR (2) by the third peristaltic pump (2.1). The influent water for each cycle is the effluent of the first SBR (1), which is pumped from the intermediate water tank (1.12) into the second SBR (2) by the second peristaltic pump (1.13). The influent volume is 50% of the effective volume of the reactor. After the water inlet is completed, anaerobic stirring is carried out. The anaerobic stirring time is set to 0.5 h. Since the sludge rich in heterotrophic bacteria in the first SBR (1) is put into the second SBR (2), the heterotrophic bacteria can store the limited organic matter in the influent water as an internal carbon source. The second air pump (2.9) is turned on to supply oxygen to the third SBR (2). The DO concentration is monitored in real time by the second DO probe (2.3) to maintain the DO concentration at 3.0-4.0 mg / L. The aeration time is set to 1.5-2 h, and the ammonia nitrogen concentration at the end of aeration is controlled at 10.0-15.0 mg / L. The anoxic stirring time is set to 4.5-6.5 h. The heterotrophic denitrifying bacteria use the internal carbon source to convert the nitrate nitrogen generated in the aerobic section into nitrite nitrogen. The anaerobic ammonium oxidation reaction simultaneously removes ammonia nitrogen and nitrite nitrogen. Sedimentation is carried out for 30 min, and drainage is carried out for 5 min. When the NAR in the aerobic section rises by more than 5%, the effluent COD concentration is less than 40.0 mg / L, the ammonia nitrogen concentration is less than 10.0 mg / L, the nitrite nitrogen concentration is less than 1.0 mg / L, and the nitrate nitrogen concentration is less than 5.0 mg / L for more than 3 consecutive days, Stage 2 ends.

[0012] Stage 3: Nitrification activity recovers, and simultaneous nitrification - denitrification coupling with anaerobic ammonium oxidation occurs. It operates 2 cycles per day. The specific operation mode is as follows: Sludge is discharged every other cycle. The volume ratio of the sludge discharged before sedimentation is 5% - 8% and enters the sludge discharge tank (2.12). After being washed through a 70 - mesh sieve, the flocculent sludge is removed, and the granular sludge is retained and put back into the second SBR (2). Sludge is added every other cycle. Before the start of water inlet, the excess sludge of the first SBR (1) with a volume ratio of 5% - 8% is washed and pumped into the second SBR (2) through the third peristaltic pump (2.1). The influent water for each cycle is the effluent of the first SBR (1), which is pumped from the intermediate water tank (1.12) into the second SBR (2) through the second peristaltic pump (1.13), and the influent volume is 50% of the effective volume of the reactor. After the water inlet is completed, anaerobic stirring is carried out, and the anaerobic stirring time is set to 0.5 h. Since the sludge rich in heterotrophic bacteria in the first SBR (1) is put into the second SBR (2), the heterotrophic bacteria can store the limited organic matter in the influent water as an internal carbon source. The second air pump (2.9) is turned on to supply oxygen to the third SBR (2). The DO concentration is monitored in real - time through the second DO probe (2.3), and the DO concentration is maintained at 3.0 - 4.0 mg / L. The aeration time is set to 1 - 1.5 h, and the ammonia - nitrogen concentration at the end of aeration is controlled to be 10.0 - 15.0 mg / L. The anoxic stirring time is set to 4.5 - 6.5 h. Sedimentation lasts for 30 min, and drainage lasts for 5 min. Due to the long - term sludge discharge and washing out of nitrifying bacteria (including AOB and NOB) in the inoculated sludge, the number of nitrifying bacteria in the sludge strengthened by sludge addition is extremely small. After the recovery in Stage 2 and Stage 3, AOB in it grows prior to NOB, the activity of AOB in the aerobic section recovers and nitrite - nitrogen accumulation occurs. In the anoxic section, anaerobic ammonium oxidation utilizes the remaining ammonia - nitrogen and nitrite - nitrogen after the end of aeration, and endogenous denitrification also provides nitrite - nitrogen. When the NAR in the aerobic section is greater than 60%, the effluent COD concentration is less than 40.0 mg / L, the ammonia - nitrogen concentration is less than 1.0 mg / L, the nitrite - nitrogen concentration is less than 1.0 mg / L, and the nitrate - nitrogen concentration is less than 1.0 mg / L for more than 3 consecutive days, it is considered that the simultaneous nitrification - denitrification double - coupling anaerobic ammonium oxidation is successful.

[0013] The present invention provides a method and device for highly efficient nitrogen removal by simultaneous nitrification - denitrification double - coupling anaerobic ammonium oxidation. The advantages are as follows:

[0014] 1) By simultaneously discharging and adding sludge, while washing out NOB and domesticating AOB, it has guiding significance for the startup or recovery of simultaneous nitrification.

[0015] 2) The added sludge introduces some heterotrophic denitrifying bacteria groups, which can reduce nitrate - nitrogen to nitrite - nitrogen in the anoxic section, providing another source of nitrite - nitrogen for anaerobic ammonium oxidation and improving the nitrogen removal efficiency of the whole process.

[0016] 3) This method does not require additional reagents and equipment, is easy to operate, and reduces the energy consumption and cost of sewage treatment. Brief Description of the Drawings

[0017] Figure 1 It is a schematic diagram of the device of the present invention.

[0018] Figure 1 In the figure: 1 - the first SBR; 2 - the second SBR. Among them, 1.1 - the raw sewage water tank of the city; 1.2 - the first peristaltic pump; 1.3 - the first stirrer; 1.4 - the first DO probe; 1.5 - the first pH probe; 1.6 - the first overflow port; 1.7 - the first sludge discharge port; 1.8 - the first drainage port; 1.9 - the first aeration head; 1.10 - the first air pump; 1.11 - the first gas flowmeter; 1.12 - the intermediate water tank; 1.13 - the second peristaltic pump; 1.14 - the sludge storage tank; 2.1 - the third peristaltic pump; 2.2 - the second stirrer; 2.3 - the second DO probe; 2.4 - the second pH probe; 2.5 - the second overflow port; 2.6 - the second sludge discharge port; 2.7 - the second drainage port; 2.8 - the second aeration head; 2.9 - the second air pump; 2.10 - the second gas flowmeter; 2.11 - the effluent water tank; 2.12 - the sludge discharge bucket.

[0019] Figure 2 It is the operation mode of the first SBR.

[0020] Figure 3 It is the operation mode of the second SBR. Detailed Embodiments

[0021] The present invention will be described in detail in combination with the drawings and examples:

[0022] Such as Figure 1As shown in the figure, the device used in the present invention includes that the raw urban sewage water tank (1.1) enters the first SBR (1) through the first peristaltic pump (1.2); the first SBR is provided with a first stirrer (1.3), a first DO probe (1.4), a first pH probe (1.5), a first overflow port (1.6), a first sludge discharge port (1.7), a first drainage port (1.8), a first aeration head (1.9) is arranged at the bottom of the first SBR (1), the first air pump (1.10) is connected to the first aeration head (1.9), and the air flow rate is controlled by the first gas flowmeter (1.11). The water discharged from the first SBR (1) enters the intermediate water tank (1.12), and is pumped into the second SBR (2) through the second peristaltic pump (1.13). The excess sludge enters the sludge storage tank (1.14) through the first sludge discharge port (1.7), and after elutriation, the excess sludge is pumped into the second SBR (2) through the third peristaltic pump (2.1). The second SBR (2) is provided with a second stirrer (2.2), a second DO probe (2.3), a second pH probe (2.4), a second overflow port (2.5), a second sludge discharge port (2.6), a second drainage port (2.7), a second aeration head (2.8) is arranged at the bottom, the second air pump (2.9) is connected to the second aeration head (2.8), and the air flow rate is controlled by the second gas flowmeter (2.10); the water discharged from the second SBR (2) enters the effluent water tank (2.11), and the discharged excess sludge enters the sludge discharge bucket (2.12).

[0023] The domestic sewage in the specific implementation experiment was taken from the septic tank of a residential area in Beijing, where the COD was 160.0 - 220.0 mg / L, the ammonia nitrogen concentration was 40.0 - 70.0 mg / L, the concentrations of nitrite nitrogen and nitrate nitrogen were both less than 1.0 mg / L, and the total phosphorus concentration was 3.0 - 6.0 mg / L.

[0024] It includes the following steps:

[0025] (I) Start-up and operation of the first SBR: The first SBR (1) is inoculated with full-scale nitrifying sludge, and the sludge concentration is maintained at 2000 - 3000 mg / L. The start-up and operation of the first SBR (1) include the following two stages:

[0026] In the first stage, the influent is domestic sewage from the city, and the influent volume is 50% of the effective volume of the reactor. It operates in an anaerobic-aerobic mode, with 4 cycles per day. After anaerobic stirring for 30 - 60 minutes, aeration is carried out. The aerobic stirring time is 30 - 60 minutes, sedimentation is 30 minutes, and drainage is 5 minutes. The DO concentration is monitored in real time online through the first DO probe (1.4), and the DO concentration in the aerobic section is maintained at 0.5 - 2.0 mg / L. Before the end of each cycle, the SRT is controlled at 5 - 10 days by sludge discharge. When the effluent COD concentration is less than 100 mg / L, the phosphate concentration is less than 0.5 mg / L, and the difference in ammonia nitrogen concentration between the influent and the effluent is less than 5 mg / L and remains for more than 3 consecutive days, it is considered that the first SBR (1) has been successfully started.

[0027] In the second stage, the influent is domestic sewage from the city, and the influent volume is 50% of the effective volume of the reactor. It operates in an anaerobic-aerobic mode, with 4 cycles per day. After anaerobic stirring for 30 - 60 minutes, aeration is carried out. The aerobic stirring time is 30 - 60 minutes, sedimentation is 30 minutes, and drainage is 5 minutes. The DO concentration is monitored in real time online through the first DO probe (1.4), and the DO concentration in the aerobic section is maintained at 0.5 - 2.0 mg / L. Before the end of each cycle, the SRT is controlled at 5 - 10 days by sludge discharge. The effluent COD concentration is less than 100 mg / L, the phosphate concentration is less than 0.5 mg / L, and the difference in ammonia nitrogen concentration between the influent and the effluent is less than 5 mg / L and can be stably maintained for more than 100 days.

[0028] (II) Start-up and operation of the second SBR: The second SBR (2) is inoculated with full nitrification floc sludge and anaerobic ammonium oxidation granular sludge, and the sludge concentration is maintained at 1800 - 2000 mg / L. The operation of the second SBR (2) includes the following three stages.

[0029] Phase 1: Complete nitrification without anammox. Operate 2 cycles per day, and the specific operation is as follows: The influent is the effluent of the first SBR (1), which is pumped from the intermediate water tank (1.12) into the second SBR (2) through the second peristaltic pump (1.13), and the influent volume is 50% of the effective volume of the reactor. After the influent ends, anaerobic stirring is carried out, and the anaerobic stirring time is set to 0.5 h. The second air pump (2.9) is turned on to supply oxygen to the third SBR (2), and the DO concentration is monitored in real time through the second DO probe (2.3) to maintain the DO concentration at 2.0 - 3.0 mg / L, and the aeration time is set to 1 - 1.5 h. Control the ammonia nitrogen concentration at the end of aeration to be 10.0 - 15.0 mg / L. The anoxic stirring time is set to 4.5 - 6.5 h, sedimentation for 30 min, and drainage for 5 min. When the NAR in the aerobic section is less than 5%, the difference between the ammonia nitrogen concentration and the nitrate nitrogen concentration at the initial and final stages of the anoxic section is less than 3 mg / L, the effluent COD concentration is 40.0 - 50.0 mg / L and remains for more than 3 consecutive days, it is considered that the second SBR (2) has been successfully started and Phase 1 ends.

[0030] In Stage 2, sludge discharge and sludge feeding are carried out simultaneously. Nitrification is inhibited, and shortcut denitrification coupled with anaerobic ammonium oxidation occurs. It operates 2 cycles per day. The specific operation is as follows: Sludge is discharged every other cycle. The volume ratio of the sludge discharged before sedimentation is 5%-8% and enters the sludge discharge tank (2.12). The flocculent sludge is washed out through a 70-mesh sieve, and the granular sludge is retained and put back into the second SBR (2). Sludge is fed every other cycle. After washing the excess sludge with a volume ratio of 5%-8% of the first SBR (1) before the start of water inlet, it is pumped into the second SBR (2) by the third peristaltic pump (2.1). The influent for each cycle is the effluent of the first SBR (1), which is pumped into the second SBR (2) from the intermediate water tank (1.12) by the second peristaltic pump (1.13). The influent volume is 50% of the effective volume of the reactor. After the water inlet ends, anaerobic stirring is carried out. The anaerobic stirring time is set to 0.5 h. Since the sludge rich in heterotrophic bacteria in the first SBR (1) is put into the second SBR (2), the heterotrophic bacteria can store the limited organic matter in the influent as an internal carbon source. The second air pump (2.9) is turned on to supply oxygen to the third SBR (2). The DO concentration is monitored in real time through the second DO probe (2.3) to maintain the DO concentration at 3.0 - 4.0 mg / L. The aeration time is set to 1.5 - 2 h, and the ammonia nitrogen concentration at the end of aeration is controlled to be 10.0 - 15.0 mg / L. The anoxic stirring time is set to 4.5 - 6.5 h. The heterotrophic denitrifying bacteria use the internal carbon source to convert the nitrate nitrogen generated in the aerobic section into nitrite nitrogen, and the anaerobic ammonium oxidation reaction simultaneously removes ammonia nitrogen and nitrite nitrogen. Sedimentation is carried out for 30 min, and drainage is carried out for 5 min. When the NAR in the aerobic section rises by more than 5%, the effluent COD concentration is less than 40.0 mg / L, the ammonia nitrogen concentration is less than 10.0 mg / L, the nitrite nitrogen concentration is less than 1.0 mg / L, and the nitrate nitrogen concentration is less than 5.0 mg / L for more than 3 consecutive days, Stage 2 ends.

[0031] In Stage 3, nitrification activity is restored, and shortcut nitrification-shortcut denitrification coupled with anaerobic ammonium oxidation occurs. It operates 2 cycles per day. The specific operation mode is as follows: Sludge is discharged every other cycle. The volume ratio of the sludge discharged before sedimentation is 5%-8% and enters the sludge discharge tank (2.12). The flocculent sludge is washed out through a 70-mesh sieve, and the granular sludge is retained and re-put into the second SBR (2). Sludge is added every other cycle. Before the start of water inlet, the excess sludge of the first SBR (1) with a volume ratio of 5%-8% is washed and pumped into the second SBR (2) through the third peristaltic pump (2.1). The influent water for each cycle is the effluent of the first SBR (1), which is pumped from the intermediate water tank (1.12) into the second SBR (2) through the second peristaltic pump (1.13), and the influent volume is 50% of the effective volume of the reactor. After the water inlet ends, anaerobic stirring is carried out, and the anaerobic stirring time is set to 0.5 h. Since the sludge rich in heterotrophic bacteria in the first SBR (1) is put into the second SBR (2), the heterotrophic bacteria can store the limited organic matter in the influent water as an internal carbon source. The second air pump (2.9) is turned on to supply oxygen to the third SBR (2). The DO concentration is monitored in real time through the second DO probe (2.3), and the DO concentration is maintained at 3.0-4.0 mg / L. The aeration time is set to 1-1.5 h, and the ammonia nitrogen concentration at the end of aeration is controlled to be 10.0-15.0 mg / L. The anoxic stirring time is set to 4.5-6.5 h. Sedimentation is carried out for 30 min, and drainage is carried out for 5 min. Since the nitrifying bacteria (including AOB and NOB) in the inoculated sludge are washed out by long-term sludge discharge, the number of nitrifying bacteria in the sludge strengthened and added is extremely small. After the recovery in Stage 2 and Stage 3, AOB in it grows prior to NOB, the activity of AOB in the aerobic section is restored, and nitrite nitrogen accumulation occurs. In the anoxic section, anaerobic ammonium oxidation utilizes the remaining ammonia nitrogen and nitrite nitrogen after the end of aeration, and endogenous denitrification also provides nitrite nitrogen. When the NAR in the aerobic section is greater than 60%, the effluent COD concentration is less than 40.0 mg / L, the ammonia nitrogen concentration is less than 1.0 mg / L, the nitrite nitrogen concentration is less than 1.0 mg / L, and the nitrate nitrogen concentration is less than 1.0 mg / L for more than 3 consecutive days, it is considered that the shortcut nitrification-shortcut denitrification double-coupled anaerobic ammonium oxidation is successful.

[0032] The experimental results show that after the reactor operates stably, the effluent total nitrogen concentration is less than 5.0 mg / L, the ammonia nitrogen concentration is less than 1.0 mg / L, and the COD concentration is less than 40.0 mg / L, achieving deep nitrogen removal and stable operation in the long term.

Claims

1. A method for highly efficient nitrogen removal by short-cut nitrification-short-cut denitrification double-coupled anaerobic ammonium oxidation, characterized in that: The device used in this method includes that the raw water tank of urban domestic sewage (1.1) enters the first SBR (1) through the first peristaltic pump (1.2); the first SBR is equipped with a first stirrer (1.3), a first DO probe (1.4), a first pH probe (1.5), a first overflow port (1.6), a first sludge discharge port (1.7), a first drain port (1.8), a first aeration head (1.9) is arranged at the bottom of the first SBR (1), the first air pump (1.10) is connected to the first aeration head (1.9), and the aeration volume is controlled by the first gas flowmeter (1.11). The effluent of the first SBR (1) enters the intermediate water tank (1.12) and is pumped into the second SBR (2) through the second peristaltic pump (1.13). The excess sludge enters the sludge storage tank (1.14) through the first sludge discharge port (1.7). After elutriation, the excess sludge is pumped into the second SBR (2) through the third peristaltic pump (2.1). The second SBR (2) is equipped with a second stirrer (2.2), a second DO probe (2.3), a second pH probe (2.4), a second overflow port (2.5), a second sludge discharge port (2.6), a second drain port (2.7), a second aeration head (2.8) is arranged at the bottom, the second air pump (2.9) is connected to the second aeration head (2.8), and the aeration volume is controlled by the second gas flowmeter (2.10); the effluent of the second SBR (2) enters the effluent water tank (2.11), and the discharged excess sludge enters the sludge discharge bucket (2.12); It is characterized by including the following steps: (I) Start-up and operation of the first SBR: The first SBR (1) is inoculated with full nitrification sludge, and the sludge concentration is maintained at 2000 - 3000 mg / L; The start-up and operation of the first SBR (1) include the following two stages: (1) In the first stage, the influent is urban domestic sewage, and the influent volume is 50% of the effective volume of the reactor; It operates in an anaerobic-aerobic mode, with 4 cycles per day; After anaerobic stirring for 30 - 60 min, aeration is carried out. The aerobic stirring time is 30 - 60 min, sedimentation is 30 min, and drainage is 5 min; The DO concentration is monitored online in real time through the first DO probe (1.4), and the DO concentration in the aerobic section is maintained at 0.5 - 2.0 mg / L; Before the end of each cycle reaction, the SRT is controlled at 5 - 10 days by sludge discharge; When the effluent COD concentration is less than 100 mg / L, the phosphate concentration is less than 0.5 mg / L, and the difference in ammonia nitrogen concentration between the influent and effluent is less than 5 mg / L and remains for more than 3 consecutive days, it is considered that the start-up of the first SBR (1) is successful; In the second stage, the influent is domestic sewage from the city, and the influent volume is 50% of the effective volume of the reactor. It operates in an anaerobic-aerobic mode, with 4 cycles per day. After anaerobic stirring for 30 - 60 minutes, aeration is carried out. The aerobic stirring time is 30 - 60 minutes, sedimentation is 30 minutes, and drainage is 5 minutes. The DO concentration is monitored in real time online through the first DO probe (1.4), and the DO concentration in the aerobic section is maintained at 0.5 - 2.0 mg / L. Before the end of each cycle reaction, the SRT is controlled at 5 - 10 days by sludge discharge. The effluent COD concentration is less than 100 mg / L, the phosphate concentration is less than 0.5 mg / L, and the difference in ammonia nitrogen concentration between the influent and effluent is less than 5 mg / L and is stably maintained for more than 100 days. (II) Start-up and operation of the second SBR: The second SBR (2) is inoculated with full nitrification flocculent sludge and anaerobic ammonium oxidation granular sludge, and the sludge concentration is maintained at 1800 - 2000 mg / L. The start-up and operation of the second SBR (2) include the following three stages: In the first stage, complete nitrification without anaerobic ammonium oxidation. It operates 2 cycles per day. The specific operation is as follows: The influent is the effluent of the first SBR (1), which is pumped into the second SBR (2) from the intermediate water tank (1.12) through the second peristaltic pump (1.13), and the influent volume is 50% of the effective volume of the reactor. After the influent ends, anaerobic stirring is carried out, and the anaerobic stirring time is set to 0.5 h. The second air pump (2.9) is turned on to supply oxygen to the second SBR (2), and the DO concentration is monitored in real time through the second DO probe (2.3) to maintain the DO concentration at 2.0 - 3.0 mg / L. The aerobic time is set to 1 - 1.5 h. The ammonia nitrogen concentration at the end of aeration is controlled at 10 - 15 mg / L. The anoxic stirring time is set to 4.5 - 6.5 h. Sedimentation is 30 minutes, and drainage is 5 minutes. When the NAR in the aerobic section is less than 5%, and the difference in ammonia nitrogen concentration and nitrate nitrogen concentration between the initial and final stages of the anoxic section is less than 3 mg / L and remains for more than 3 consecutive days, it is considered that the second SBR (2) has been successfully started, and the first stage ends. In Stage 2, sludge discharge and sludge feeding are carried out simultaneously. Nitrification is inhibited, and shortcut denitrification coupled with anaerobic ammonium oxidation occurs. It operates for 2 cycles per day. The specific operation is as follows: Sludge is discharged every other cycle. The volume ratio of the sludge discharged before precipitation is 5%-8% and enters the sludge discharge tank (2.12). The flocculent sludge is washed out through a 70-mesh sieve, and the granular sludge is retained and re-put into the second SBR (2); Sludge is fed every other cycle. After washing the excess sludge with a volume ratio of 5%-8% of the first SBR (1) before the start of water inlet, it is pumped into the second SBR (2) by the third peristaltic pump (2.1); The influent water for each cycle is the effluent of the first SBR (1), which is pumped into the second SBR (2) from the intermediate water tank (1.12) by the second peristaltic pump (1.13). The influent volume is 50% of the effective volume of the reactor; After the water inlet is completed, anaerobic stirring is carried out. The anaerobic stirring time is set to 0.5 h; The second air pump (2.9) is turned on to supply oxygen to the second SBR (2). The DO concentration is monitored in real time through the second DO probe (2.3) to maintain the DO concentration at 3.0-4.0 mg / L. The aeration time is set to 1.5-2 h, and the ammonia nitrogen concentration at the end of aeration is controlled to be 10-15 mg / L; The anoxic stirring time is set to 4.5-6.5 h; Sedimentation is carried out for 30 min and drainage is carried out for 5 min; When the NAR in the aerobic section is greater than 5%, the effluent ammonia nitrogen concentration is less than 10.0 mg / L, the nitrite nitrogen concentration is less than 1.0 mg / L, and the nitrate nitrogen concentration is less than 5.0 mg / L for more than 3 consecutive days, Stage 2 ends; Stage 3: Nitrification activity is restored, and short-cut nitrification-short-cut denitrification dual-coupled anaerobic ammonium oxidation occurs; it operates 2 cycles per day. The specific operation mode is as follows: sludge discharge is carried out every other cycle, and the volume ratio of the sludge discharged before sedimentation is 5%-8% and enters the sludge discharge bucket (2.12), and the flocculent sludge is washed out through a 70-mesh sieve, and the granular sludge is retained and re-put into the second SBR (2); sludge feeding is carried out every other cycle, and the excess sludge with a volume ratio of 5%-8% of the first SBR (1) is washed and pumped into the second SBR (2) by the third peristaltic pump (2.1) before the start of water inlet; the influent water for each cycle is the effluent of the first SBR (1), which is pumped from the intermediate water tank (1.12) into the second SBR (2) by the second peristaltic pump (1.13), and the influent water volume is 50% of the effective volume of the reactor; after the water inlet ends, anaerobic stirring is carried out, and the anaerobic stirring time is set to 0.5 h; the second air pump (2.9) is turned on to supply oxygen to the second SBR (2), and the DO concentration is monitored in real time through the second DO probe (2.3) to maintain the DO concentration at 3.0-4.0 mg / L, the aeration time is set to 1-1.5 h, and the ammonia nitrogen concentration at the end of aeration is controlled to be 10-15 mg / L; the anoxic stirring time is set to 4.5-6.5 h; sedimentation is carried out for 30 min and drainage is carried out for 5 min; when the NAR in the aerobic section is greater than 60%, the effluent ammonia nitrogen concentration is less than 1.0 mg / L, the nitrite nitrogen concentration is less than 1.0 mg / L, and the nitrate nitrogen concentration is less than 1.0 mg / L for more than 3 consecutive days, it is considered that the short-cut nitrification-short-cut denitrification dual-coupled anaerobic ammonium oxidation is successful.

Images