A method for simultaneous denitrification and chlorine removal by coupling short-cut nitrification and denitrification with perchlorate reduction

Abstract

The present invention belongs to the technical field of biological treatment of wastewater and relates to a method for synchronous denitrification and dechlorination by coupling nitrification and denitrification with perchlorate reduction. In the first stage, anaerobic activated sludge is inoculated in the reactor and cultured anaerobic and heterotrophically to start the perchlorate reduction reaction; in the second stage, aerobic nitrification sludge is inoculated and cultured aerobic and anaerobic to strengthen the nitrite reaction; in the third stage, the aeration time and aeration volume are reduced to suppress NO2 in the aerobic period. ‑ Oxidized to NO3 ‑ , while simultaneously improving denitrification and perchlorate reduction reactions during the anaerobic phase, strengthening the nitritation process, and thereby achieving stable short-range nitrification and denitrification coupled with perchlorate reduction. The method for simultaneous denitrification and dechlorination provided by the present invention has a good treatment effect on wastewater containing ammonium perchlorate. The final effluent ammonia nitrogen and perchlorate degradation rates are above 80%, the nitritation rate is above 90%, and the total nitrogen removal rate is above 80%, providing a new research approach for the simultaneous removal of ammonium perchlorate.

Description

Technical Field

[0001] The invention belongs to the technical field of biological treatment of wastewater, and in particular relates to a method for synchronous denitrification and dechlorination by coupling short-range nitrification and denitrification with perchlorate reduction. Background Art

[0002] Perchlorate is a persistent chemical pollutant that can exist for decades under normal environmental conditions. Ammonium perchlorate (NH4ClO4, AP) accounts for about 90% of all manufactured perchlorates and is widely used in solid rocket fuel, missiles, explosives, fireworks and other fields. The large-scale use of AP and improper disposal methods have led to serious pollution problems in water bodies, soil and other environments. AP is highly soluble in water and usually dissociates into ClO4 - and NH4 + Therefore, AP-contaminated wastewater often contains ClO4 - and NH4 + The problem of shared pollution.

[0003] Targeting ClO4 - The main removal methods include adsorption, ion exchange and biological treatment, among which biological methods are widely used due to their high efficiency, economy and no secondary pollutants. - The biodegradation of perchlorate-reducing bacteria is carried out under anaerobic conditions to - As an electron acceptor, ClO4 - Reduced to chlorate and chlorite, and finally to Cl - The current ClO4 - The biodegradation process can only achieve ClO4 in AP wastewater - Removal of NH4 + The removal of NO2 requires the help of other denitrification processes, such as nitrification-denitrification or anaerobic ammonium oxidation. Traditional nitrification-denitrification processes often consume a lot of oxygen and organic matter, which leads to high operating costs of sewage treatment plants. As an emerging biological denitrification process, short-range nitrification-denitrification can save about 25% of oxygen supply and 40% of carbon source in the denitrification process. How to control the nitrification reaction to stay at NO2 - The stage is the key to achieve short-term nitrification-denitrification biological denitrification. Studies have shown that reducing dissolved oxygen (DO) has little effect on ammonia oxidation, but can significantly hinder NO2 - Therefore, by regulating the DO concentration, the nitrite reaction can be enhanced, and the short-term nitrification-denitrification process can be initiated, thereby achieving economical and efficient denitrification.

[0004] Currently ClO4 -and NH4 + The biodegradation technology is relatively mature, but it is only for a single removal process and has no effect on ClO4 - and NH4 + There are few studies on the simultaneous removal process of NH4 + It can provide nitrogen source for perchlorate reducing bacteria and nitrifying-denitrifying bacteria, ClO4 - The O2 released during the biodegradation process can provide a local aerobic environment for ammonia oxidizing bacteria, which is conducive to the occurrence of short-term nitrification reaction. Therefore, it is theoretically feasible to couple the short-term nitrification-denitrification and perchlorate reduction processes in the same reaction system, which is a good opportunity for ClO4 - and NH4 + It provides an effective way to remove the synchronous Summary of the Invention

[0005] The purpose of the present invention is to solve the above-mentioned problems existing in the prior art. A method for synchronous denitrification and chlorine removal by coupling short-term nitrification and denitrification with perchlorate reduction is proposed. A sequencing batch reactor (SBR) is used to sequentially inoculate anaerobic activated sludge and aerobic nitrification sludge, and a "three-stage" culture mode is adopted to achieve rapid startup and stable operation of short-term nitrification and denitrification coupled with perchlorate reduction.

[0006] The technical solution of the present invention is:

[0007] The present invention utilizes sequencing batch reactor (SBR) to sequentially inoculate anaerobic activated sludge and aerobic nitrification sludge, and adopts the method of starting perchlorate reduction first and then starting short-cut nitrification to achieve the coupling of short-cut nitrification-denitrification and perchlorate reduction, thereby achieving NH4 + and ClO4 - The method consists of three stages: in the first stage, anaerobic activated sludge is inoculated, anaerobic heterotrophic culture is adopted, sodium acetate is used as the organic carbon source, and the perchlorate reduction reaction is started; in the second stage, aerobic nitrification sludge is inoculated, aerobic-anaerobic culture is adopted, and nitrite reaction is started; in the third stage, NO2 is suppressed in the aerobic period by reducing the aeration time and aeration volume. - Oxidized to NO3 - , strengthen the nitrite reaction while enhancing the denitrification and perchlorate reduction reaction in the anaerobic period, thereby achieving the purpose of short-term nitrification-denitrification coupling perchlorate reduction and realizing stable NH4 + and ClO4 - Synchronous removal.

[0008] The present invention provides a method for synchronous denitrification and chlorine removal by coupling short-cut nitrification and denitrification with perchlorate reduction, wherein the method adopts a sequencing batch reactor and comprises the following steps:

[0009] (1) Anaerobic activated sludge was inoculated in the reactor, and anaerobic heterotrophic culture was adopted. Sodium acetate was used as the organic carbon source, and the operation cycle was 30-50 minutes for water inlet period, 2-7 minutes for stirring period, 7-9 hours for anaerobic period, 10-20 minutes for drainage period, and 14-16 hours for static period.

[0010] (2) Inoculate aerobic nitrification sludge in the reactor at a ratio of 1:1 to 2:1 of anaerobic activated sludge to aerobic nitrification sludge, adopt an aerobic-anaerobic culture method, and operate the reactor with a water inlet period of 30 to 50 minutes, a stirring period of 2 to 7 minutes, an aerobic period of 4 to 6 hours, an anaerobic period of 7 to 9 hours, a drainage period of 10 to 20 minutes, and a static period of 9 to 11 hours; at the same time, control the DO concentration in the aerobic period to be above 2 mg / L;

[0011] (3) The reactor was adjusted to operate in cycles of 30-50 min for the water inlet period, 2-7 min for the stirring period, 3-7 min for the aerobic period, 7-9 h for the anaerobic period, 10-20 min for the drainage period, and 14-16 h for the static period. The DO concentration in the aerobic period was controlled at 1.0-1.5 mg / L.

[0012] Furthermore, the water inlet rate of the reactor is 0.6-1.2 L / h, and the stirring speed is 90-135 r / min.

[0013] Preferably, the water inlet rate is 1 L / h; preferably, the stirring speed is 110 r / min.

[0014] Furthermore, the reactor was operated in the dark, with pH stabilized at 7.0 to 8.0, temperature controlled at 20 to 25° C., and C / N of 2 to 3. Specifically, the reactor was covered with black cloth during operation, with pH 7.5, temperature 23° C., and C / N≈2.2.

[0015] Furthermore, the gas flow rate during the aerobic period is controlled at 3-4 L / min, and the aeration position is at 1 / 4 of the distance from the bottom of the reactor.

[0016] Furthermore, the cycle in step (1) is: water inlet period of 40 minutes, stirring period of 5 minutes, anaerobic period of 8 hours, drainage period of 15 minutes, and static period of 15 hours.

[0017] Furthermore, the cycle in step (2) is: water inlet period of 40 minutes, stirring period of 5 minutes, aerobic period of 5 hours, anaerobic period of 8 hours, drainage period of 15 minutes, and static period of 10 hours.

[0018] Furthermore, the cycle in step (3) is: water inlet period of 40 minutes, stirring period of 5 minutes, aerobic period of 5 minutes, anaerobic period of 8 hours, drainage period of 15 minutes, and static period of 15 hours.

[0019] Furthermore, the operation time of step (1) is 1 to 29 days, the operation time of step (2) is 30 to 62 days, and the operation time of step (3) is 63 to 100 days.

[0020] Furthermore, the water added to the reactor is synthetic wastewater, the components of which include:

[0021] 0.95g / LKH2PO4, 1.5g / LNa2HPO4·12H2O, 0.12g / LMgSO4·7H2O, 1.8g / L CH3COONa, 10mMNaClO4, 10mM NH4Cl, C / N≈2.2, 1mL of trace element I and trace element II solution; trace element I: 5g / LNa2·EDTA·2H2O, 5g / L FeSO4·7H2O, trace element II: 0.1g / L ZnSO4·7H2O, 0.2g / L CoCl2·6H2O, 0.01g / L CuSO4·5H2O, 0.03g / LNa2MoO4·2H2O, 0.02g / LNiCl2·6H2O, 0.05g / LH3BO3·H2O; the wastewater pH is 7.0-8.0; preferably, the wastewater pH is 7.5;

[0022] The wastewater added in step (1) does not contain NH4Cl.

[0023] Beneficial effects of the present invention:

[0024] The method for simultaneous denitrification and dechlorination provided by the present invention adopts a "three-stage" mode, sequentially inoculating anaerobic activated sludge and aerobic nitrification sludge, and adopts a method of first starting perchlorate reduction and then starting short-range nitrification, thereby achieving the coupling of short-range nitrification-denitrification and perchlorate reduction, thereby achieving simultaneous removal of NH4 + and ClO4 - The final effluent NH4 + and ClO4 - The degradation rate is above 80%, the nitrification rate is above 90%, and the total nitrogen (TN) removal rate is above 80%, which is NH4 + and ClO4 - The study of simultaneous removal of BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the sequencing batch reactor SBR of the present invention;

[0026] Figure 2 NH4 for inlet and outlet water + and ClO4 - Concentration change and degradation rate diagram; in the figure, the horizontal axis is the incubation time, the vertical axis is the concentration change and NH4+ and ClO4 - removal rate;

[0027] Figure 3 For inlet and outlet water NO2 - 、NO3 - Concentration change and nitrite accumulation rate graph; in the graph, the horizontal axis is the culture time, and the vertical axis is the concentration change and nitrite accumulation rate;

[0028] Figure 4 This is a graph of the total nitrogen concentration changes and degradation rates in the inlet and outlet water; in the graph, the horizontal axis is the incubation time, and the vertical axis is the concentration change and degradation rate. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] In order to further understand the present invention, the present invention will be further described with reference to the accompanying drawings and embodiments.

[0031] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0032] Unless otherwise specified, the experimental methods in the following examples are conventional methods and were performed according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials and reagents used in the following examples, unless otherwise specified, were all commercially available.

[0033] The sequencing batch reactor (SBR) used in the present invention is a cylindrical glass container with an effective volume of 2 L, a diameter of 100 mm and a height of 250 mm. Figure 1 As shown, the SBR includes an electric motor (1), an upper water outlet (2), a middle water outlet (3), a water inlet (4), a constant flow pump (5), a water inlet bottle (6), an aeration port (7), a DO detection port (8), a dissolved oxygen meter (9), an air pump (10), a waste liquid collection device (11), an agitator (12), and a glass round cover (13). The electric motor (1) is connected to the agitator (12) inside the reactor, the constant flow pump (5) is connected to the water inlet bottle (6) and the water inlet (4), the upper water outlet (2) and the middle water outlet (3) are connected to the waste liquid collection device (11), the air pump (10) is connected to the aeration port (7) on the reactor, and the DO monitoring port (8) is externally connected to the dissolved oxygen meter (9) and is internally connected to the reactor.

[0034] SBR adopts the operation mode of intermittent water inlet, intermittent aeration and DO control. Each cycle includes: water inlet period, stirring period, aerobic period, anaerobic period, drainage period and static period.

[0035] During operation, 1L of synthetic wastewater is pumped into the reactor from the lower water inlet (4) to 2 / 3 through a constant flow pump (5), and the excess wastewater is discharged from the upper water outlet (2). After each cycle of water inflow is completed, water samples are taken from the reactor to determine ClO4 - 、NO2 - 、NO3 - and NH4 + concentration.

[0036] The perchlorate reduction start-up phase of step (1) is as follows: 400-600 mL of anaerobic activated sludge is inoculated in the reactor, and an anaerobic heterotrophic culture method is adopted. The reactor is operated in a cycle with a water inlet period of 30-50 min, a stirring period of 2-7 min, an anaerobic period of 7-9 h, a drainage period of 10-20 min, and a static period of 14-16 h. Sodium acetate is used as the organic carbon source and ClO4- is used as the electron acceptor for the reduction reaction. The operation time of this phase is 1-29 days. After each cycle, the sample in the reactor is sampled and analyzed to determine the ClO4 in the sample. - 、NO2 - 、NO3 - and NH4 + concentration.

[0037] In the nitrification reaction start-up phase of step (2), 200-300 mL of aerobic nitrification sludge is inoculated in the reactor, ensuring that the inoculation ratio of anaerobic activated sludge to aerobic nitrification sludge is 1:1-2:1, and an aerobic-anaerobic culture method is adopted. The SBR is operated in a cycle of a water inlet period of 30-50 minutes, a stirring period of 2-7 minutes, an aerobic period of 4-6 hours, an anaerobic period of 7-9 hours, a drainage period of 10-20 minutes, and a static period of 9-11 hours. When entering the aerobic period, an air pump (10) aerates the reactor from the upper aeration port (7), and the gas flow rate is controlled at 3-4 L / m in, DO concentration is controlled at more than 2 mg / L, and the aeration position is 1 / 4 of the distance from the bottom of the reactor to reduce the direct impact of aerated perchlorate-reducing bacteria; at the same time, a stirrer (12) is used to mix the sludge and wastewater, with a rotation speed of 90 to 135 r / min, and an external dissolved oxygen meter (9) is used to monitor the dissolved oxygen content inside the reactor in real time; when the DO content inside the reactor is monitored to be below 0.2 mg / L, the reactor enters the anaerobic period; after the anaerobic period ends, the wastewater is discharged from the middle outlet (3) to the waste liquid collection device (11), and samples are taken for analysis to determine the ClO4 content in the sample. - 、NO2 - 、NO3 - and NH4 +The concentration changes, and then enters the static period. This stage lasts for 30 to 62 days.

[0038] Step (3) of the short-range nitrification-denitrification coupled perchlorate reduction stable operation phase: in order to control the phenomenon of the decline of the nitrite rate and the fluctuation of the perchlorate degradation rate caused by the aeration in the previous stage, the aeration time and aeration volume are reduced to inhibit NO2 - Oxidized to NO3 - , strengthen the nitrite reaction, and at the same time enhance the denitrification and perchlorate reduction reaction; based on this, adjust the SBR to operate in cycles of 30-50min water inlet period, 2-7min stirring period, 3-7min aerobic period, 7-9h anaerobic period, 10-20min drainage period, and 14-16h static period; when entering the aerobic period, the gas flow rate is controlled at 1-2L / min, and the DO concentration in the aerobic period is controlled at 1.0-1.5mg / L; the operation time of this stage is 63-100d; after the operation, the samples in the reactor are sampled and analyzed to determine the ClO4 - 、NO2 - 、NO3 - and NH4 + concentration.

[0039] The reactor is covered with black cloth during operation, the pH is stabilized at 7.0-8.0, the temperature is controlled at 20-25°C, C / N≈2.2, and the stirring speed is controlled at 90-135r / min. No sludge discharge is required during the entire cultivation process, and the sludge is cultivated in the reactor for a long time.

[0040] The present invention also provides the following specific implementation method.

[0041] In a specific embodiment, the seed sludge and wastewater used are as follows:

[0042] The sludge was obtained from anaerobic activated sludge and aerobic nitrification sludge that were domesticated and matured in the laboratory;

[0043] The synthetic wastewater composition was as follows: 0.95 g / L KH2PO4, 1.5 g / L Na2HPO4·12H2O, 0.12 g / L MgSO4·7H2O, 1.8 g / L CH3COONa, 10 mM NaClO4, 10 mM NH4Cl, C / N ≈ 2.2, and 1 mL of trace element I and trace element II solutions. Trace element I: 5 g / L Na2·EDTA·2H2O, 5 g / L FeSO4·7H2O; trace element II: 0.1 g / L ZnSO4·7H2O, 0.2 g / L CoCl2·6H2O, 0.01 g / L CuSO4·5H2O, 0.03 g / L Na2MoO4·2H2O, 0.02 g / L NiCl2·6H2O, and 0.05 g / L H3BO3·H2O. The pH value is 7.0 to 8.0, and no NH4Cl is added during the start-up phase of perchlorate reduction in step (1).

[0044] The specific steps of the method are as follows:

[0045] (1) Perchlorate reduction start-up phase (1 to 29 days)

[0046] The reactor was inoculated with 400 mL of anaerobic activated sludge and cultured in an anaerobic heterotrophic manner. The reactor was operated with a water inlet period of 40 min, a stirring period of 5 min, an anaerobic period of 8 h, a drainage period of 15 min, and a static period of 15 h. Sodium acetate was used as the organic carbon source and ClO4 - Acts as an electron acceptor in reduction reactions.

[0047] After 29 days of continuous operation in this stage, the effluent ClO4 - 、NO2 - 、NO3 - The concentrations were 0.26mM, 0.036mM, and 0.012mM, respectively, and the TN removal rate was 9% ( Figure 4 ), ClO4 - and NH4 + The degradation rates were 92.8% and 1.4% ( Figure 2 ). The results show that this stage achieved a higher ClO4 - removal efficiency, and the perchlorate reduction reaction was successfully initiated.

[0048] (2) Nitrosation reaction start-up phase (30-62 days)

[0049] The reactor was inoculated with 200 mL of aerobic nitrifying sludge, maintaining an inoculum ratio of 2:1 between anaerobic activated sludge and aerobic nitrifying sludge. An aerobic-anaerobic culture system was employed, with a 40-minute influent phase, a 5-minute stirring phase, a 5-hour aerobic phase, an 8-hour anaerobic phase, a 15-minute drainage phase, and a 10-hour rest phase. During the aerobic phase, the gas flow rate was controlled at 3-4 L / min, the DO concentration was kept above 2 mg / L, and the aeration position was located 1 / 4 of the way from the bottom of the reactor to minimize direct impact of aeration on perchlorate-reducing bacteria.

[0050] In the first 15 days (30-45 days) after inoculation of aerobic nitrification sludge, the effluent NH4 + The concentration is 9.16mM; starting from the 45th day, the effluent NH4 + The concentration gradually decreased from 9mM to below the detection limit, and the degradation rate increased to more than 95% ( Figure 2 ). NO2 in the effluent - The content gradually increased to 5.69mM, and the nitrosation rate was 76.5% ( Figure 3 ), indicating that AOB and NOB in nitrifying sludge were enriched, thus achieving NH4 + The biological oxidation and nitrification reaction were successfully started. The effluent ClO4 - was 1.54 mM, and the degradation rate was 76% ( Figure 2 ), TN removal rate was 5.18% ( Figure 4 ), indicating that the activity of perchlorate-reducing bacteria was affected by the long-term aeration at this stage. It can be seen that the nitrite reaction was started by inoculating aerobic nitrification sludge at this stage, and NH4 + Oxidation, but the influence of aeration leads to ClO4 - The removal efficiency decreased and the TN removal rate remained very low.

[0051] (3) Short-range nitrification-denitrification coupled perchlorate reduction stable operation stage (63-100 days)

[0052] In order to control the phenomenon of excessive aeration in the previous stage causing the decline of nitrite rate and fluctuation of perchlorate degradation rate in the later stage, the aeration time and aeration volume were reduced to inhibit NO2 - Oxidized to NO3 - The system is operated in cycles of 40 minutes of water inflow, 5 minutes of stirring, 5 minutes of aerobic period, 8 hours of anaerobic period, 15 minutes of drainage period, and 15 hours of static period. During the aerobic period, the gas flow rate is controlled at 1-2 L / min and the DO concentration is between 1.0 and 1.5 mg / L.

[0053] The effluent NH4 of the entire stage III +The average concentration was 0.13 mM, and from 73 days on, the effluent NO3 - The concentration dropped from 4.74 mM to below the detection limit ( Figure 3 ), the nitrification rate increased to 93.3% ( Figure 3 ), indicating that at this stage, under low aeration time and aeration volume, NH4 + The removal capacity can still maintain the high level of step (2), and the TN removal rate increases from 5.18% to 81.9% ( Figure 4 ). Outlet ClO4 - The concentration was gradually reduced to 1.08 mM, ClO4 - Degradation gradually returned to stability, ClO4 - The degradation rate reaches more than 80% in step (1) ( Figure 2 ), indicating that the capacity for perchlorate reduction and denitrification reduction reactions increased.

[0054] In general, through the "three-stage" model, anaerobic activated sludge and aerobic nitrification sludge are inoculated in sequence, and the short-range nitrification is started after the perchlorate reduction, so as to achieve the coupling of short-range nitrification-denitrification and perchlorate reduction, thereby achieving the simultaneous removal of NH4 + and ClO4 - The final effluent NH4 + and ClO4 - The degradation rate is above 80%, the nitrification rate is above 90%, and the total nitrogen (TN) removal rate is above 80%, achieving NH4 + and ClO4 - Synchronous removal.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art may still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, and modifications made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for synchronous denitrification and chlorine removal by coupling short-cut nitrification and denitrification with perchlorate reduction, characterized in that: The method adopts a sequencing batch reactor and comprises the following steps: (1) The reactor was inoculated with anaerobic activated sludge containing perchlorate-reducing bacteria, and the anaerobic heterotrophic culture method was adopted. Sodium acetate was used as the organic carbon source. The operation cycle was 30-50 minutes for water inlet period, 2-7 minutes for stirring period, 7-9 hours for anaerobic period, 10-20 minutes for drainage period, and 14-16 hours for static period. (2) Inoculate aerobic nitrification sludge in the reactor at a ratio of 1:1 to 2:1 of anaerobic activated sludge to aerobic nitrification sludge, adopt an aerobic-anaerobic culture method, and operate the reactor with a water inlet period of 30 to 50 minutes, a stirring period of 2 to 7 minutes, an aerobic period of 4 to 6 hours, an anaerobic period of 7 to 9 hours, a drainage period of 10 to 20 minutes, and a static period of 9 to 11 hours; at the same time, control the DO concentration in the aerobic period to be above 2 mg / L; (3) The reactor was adjusted to operate in cycles of 30-50 min for the water inlet period, 2-7 min for the stirring period, 3-7 min for the aerobic period, 7-9 h for the anaerobic period, 10-20 min for the drainage period, and 14-16 h for the static period. The DO concentration in the aerobic period was controlled at 1.0-1.5 mg / L.

2. The method according to claim 1, characterized in that The water inlet rate of the reactor is 0.6-1.2 L / h, and the stirring speed is 90-135 r / min.

3. The method according to claim 1, characterized in that The reactor was operated in the dark, with pH stable at 7.0-8.0, temperature controlled at 20-25°C, and C / N ratio of 2-3.

4. The method according to claim 1, wherein The gas flow rate during the aerobic period is controlled at 3-4 L / min, and the aeration position is at 1 / 4 of the distance from the bottom of the reactor.

5. The method according to claim 1, wherein The cycle in step (1) is: water inlet period of 40 minutes, stirring period of 5 minutes, anaerobic period of 8 hours, drainage period of 15 minutes, and static period of 15 hours.

6. The method according to claim 1, wherein The cycle in step (2) is: water inlet period of 40 minutes, stirring period of 5 minutes, aerobic period of 5 hours, anaerobic period of 8 hours, drainage period of 15 minutes, and static period of 10 hours.

7. The method according to claim 1, characterized in that The cycle in step (3) is: water inlet period of 40 minutes, stirring period of 5 minutes, aerobic period of 5 minutes, anaerobic period of 8 hours, drainage period of 15 minutes, and static period of 15 hours.

8. The method according to claim 1, characterized in that The operation time of step (1) is 1 to 29 days, the operation time of step (2) is 30 to 62 days, and the operation time of step (3) is 63 to 100 days.

9. The method according to claim 1, characterized in that The water added to the reactor is synthetic wastewater, which contains: 0.95g / L KH2PO4, 1.5g / LNa2HPO4·12H2O, 0.12g / LMgSO4·7H2O, 1.8g / L CH3COONa, 10mMNaClO4, 10mM NH4Cl, C / N ratio of 2.2, 1mL of trace element I and trace element II solution; trace element I: 5g / LNa2·EDTA·2H2O, 5g / L FeSO4·7H2O, trace element II: 0.1g / L ZnSO4·7H2O, 0.2g / L CoCl2·6H2O, 0.01g / L CuSO4·5H2O, 0.03g / LNa2MoO4·2H2O, 0.02g / LNiCl2·6H2O, 0.05g / L H3BO3·H2O; wastewater pH is 7.0-8.0; The wastewater added in step (1) does not contain NH4Cl.

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