Method for realizing rapid enrichment of anammox bacteria by combined regulation of NLR and HRT

Abstract

The present application relates to a method for realizing anaerobic ammonia oxidation bacteria enrichment under the joint regulation of NLR and HRT in the field of sewage biological treatment technology, which aims at the problems of anaerobic ammonia oxidation bacteria being greatly affected by the environment and slow enrichment, etc. + -N and NO2 ‑ -N is pumped into the SBR reactor, and the enrichment of anaerobic ammonia oxidation bacteria is successfully realized by continuously changing the hydraulic retention time and the substrate concentration of the influent. The total nitrogen removal rate is stably maintained at 75%, which has good removal efficiency, and the flexible regulation of the reactor is beneficial to the rapid start of the anaerobic ammonia oxidation reactor, providing a theoretical reference for the practical application of the Anammox process. It is simple to operate, easy to manage, has high treatment efficiency, and has good popularization and application prospect.

Description

Technical Field

[0001] This invention belongs to the field of wastewater biological treatment technology, specifically relating to a device and method for rapidly enriching anaerobic ammonia-oxidizing bacteria through combined regulation of load and hydraulic retention time. Background Technology

[0002] Excessive nitrogen and phosphorus emissions into water bodies lead to eutrophication, one of the world's most pressing environmental problems. To protect water resources, especially in water-scarce regions, nitrogen removal from wastewater is crucial, leading many countries to implement stringent nitrogen emission standards in recent years. Typically, wastewater denitrification involves nitrification followed by denitrification; both processes are energy-intensive and require significant external carbon sources, increasing operating costs. Compared to traditional nitrification-denitrification technologies, anaerobic ammonium oxidation (ANAO) offers advantages such as lower oxygen demand, lower operating costs, and the elimination of the need for external carbon sources.

[0003] Anaerobic ammonia oxidation (ANAMMOX) is an autotrophic nitrogen removal process that uses ammonia nitrogen (NH4) as the nitrogen source. + -N) as the electron donor, with nitrite (NO2) - Anaerobic ammonia oxidation (AAO) is a biological reaction that uses electron acceptors (-N) and produces nitrogen gas as the product. Due to its advantages such as low oxygen demand, no need for external carbon sources, low sludge production, and no secondary pollution, it has broad application prospects in wastewater denitrification. Anaerobic ammonia oxidizing bacteria have a low specific growth rate, long doubling time, and are easily affected by temperature, pH, and influent substrate concentration. Therefore, exploring and optimizing the start-up conditions of anaerobic ammonia oxidation reactors is essential.

[0004] The shortcomings of existing technologies are that existing anaerobic ammonia oxidizing bacteria are difficult to enrich and are greatly affected by the environment, which limits their application to a certain extent. Summary of the Invention

[0005] The purpose of this invention is to provide a method for the rapid enrichment of anaerobic ammonia oxidizing bacteria through the combined regulation of NLR and HRT, in order to solve the problems of difficulty in enriching anaerobic ammonia oxidizing bacteria and the great influence of the environment in the prior art. The enrichment of anaerobic ammonia oxidizing bacteria is achieved by the combined regulation of load and hydraulic retention time.

[0006] Therefore, one of the objectives of this invention is achieved as follows: a method for rapid enrichment of anaerobic ammonia-oxidizing bacteria through combined regulation of NLR and HRT, comprising the following steps:

[0007] (1) Selection of sludge inoculation and reactor and setting of experimental parameters: SBR reactor was inoculated with flocculent sludge containing anaerobic ammonia oxidizing bacteria. The reactor influent was artificial simulated wastewater. The water temperature in the reactor was kept stable at 29-35℃, the pH was controlled between 7.4-8.4, and the dissolved oxygen concentration was controlled between 0-0.4mg / L. The reactor was covered with a light-shielding cloth to keep it away from light.

[0008] (2) The simulated wastewater was treated in several cycles using an SBR reactor. Each treatment cycle included: influent, reaction, sedimentation, effluent and idle, which were carried out in a cycle. The SBR reactor operated in a total of five stages. Stage I was the activity recovery period. When the removal rates of ammonia nitrogen and nitrite reached 80%, the influent matrix concentration and hydraulic retention time were adjusted to proceed to Stage II. When the removal rates of ammonia nitrogen and nitrite reached a stable value, the hydraulic retention time was adjusted to increase the nitrogen load to proceed to Stage III. When the removal rates of ammonia nitrogen and nitrite reached a stable value, the influent matrix concentration was increased to increase the nitrogen load to proceed to Stage IV. When the removal rates of ammonia nitrogen and nitrite reached a stable value, the hydraulic retention time was further reduced to increase the nitrogen load to proceed to Stage V. When the removal rates of ammonia nitrogen and nitrite reached a stable value, the process continued until the removal rates of ammonia nitrogen and nitrite in the reactor were greater than 80% and the total nitrogen removal rate was greater than 75%.

[0009] (3) Convert the simulated wastewater into the actual wastewater that needs to be treated and operate it stably for a long time.

[0010] Furthermore, in step (2), the SBR reactor runs for two cycles per day. In each cycle, the water inlet is 15-25 min, the stirring reaction time is 4.5-8 h, the settling time is 45-75 min, the drainage time is 15-25 min, and the rest is idle time. The drainage ratio is 40-60%. The reactor does not actively discharge sludge during operation.

[0011] Furthermore, the MLSS of the inoculated anaerobic ammonia oxidation flocculent sludge was 3300 mg / L, and the inoculation amount accounted for one-fifth of the SBR reactor volume.

[0012] Furthermore, the simulated wastewater influent matrix is ​​provided by NH4Cl and NaNO2, and the components of the simulated wastewater are: NH4Cl and NaNO2. + -N, 30-40 mg / L; NO2 - -N, 30-40mg / L; KH2PO4, 20mg / L; NaHCO3, 500mg / L.

[0013] Furthermore, trace elements I and II are added to the simulated wastewater daily. The composition of trace element I is Na2-EDTA·2H2O, 5000 mg / L; FeSO4·7H2O, 5000 mg / L; and the composition of trace element II is Na2-EDTA·2H2O, 15000 mg / L; ZnSO4·7H2O, 420 mg / L; CoCl2·6H2O, 240 mg / L; MnCl2·4H2O, 1000 mg / L; CuSO4·5H2O, 250 mg / L; NaMoO4·2H2O, 250 mg / L; NiCl2·6H2O, 200 mg / L; Na2SeO4, 250 mg / L; and H3BO3, 15 mg / L. The daily addition amount of trace elements I and II is 1 / 5000-1 / 20000 of the total weight of the water body on that day.

[0014] Specifically, in step (2), the reactor runs for a total of 300 cycles, corresponding to five stages;

[0015] Phase I: Running cycles 1-60, NH4 + -N influent concentration is 30 mg / L, NO2 - The influent nitrogen concentration was 40 mg / L, and the hydraulic retention time at this stage was 8 hours (average nitrogen load was 0.24 kg N / (m³)). 3 ·d));

[0016] Phase II: Run cycles 61-120; NH4 + -N, NO2 - The influent nitrogen concentration was 30 mg / L, and the hydraulic retention time was 6 h (average nitrogen load was 0.28 kg N / (m³)). 3 ·d));

[0017] Phase III: Run cycles 121-180; NH4 + -N, NO2 - The nitrogen influent concentration was kept constant at 30 mg / L, and the hydraulic retention time was adjusted to 5 h (average nitrogen load was 0.32 kg N / (m³)). 3 ·d));

[0018] Phase IV: Run cycles 181-240; NH4 is adjusted during this phase. + -N, NO2 - -N influent concentration is 40 mg / L, hydraulic retention time remains unchanged at 5 h (average nitrogen load is 0.41 kgN / (m3·d));

[0019] Phase V: Run 241-300 cycles; keep the influent ammonia nitrogen concentration constant, adjust the hydraulic retention time to 4.5 h (average nitrogen load is 0.46 kg N / (m³)). 3 ·d)).

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] (1) Using low substrate concentration influent can effectively avoid the inhibition of anaerobic ammonia oxidizing bacteria by FA and FNA.

[0022] (2) By adopting a combined regulation strategy of gradually increasing NLR and reducing HRT, the domestication and enrichment of anaerobic ammonia oxidizing bacteria were accelerated.

[0023] (3) The online control system can monitor the changes in DO and pH in the reactor in real time, while the heating rod keeps the water temperature within a suitable range, creating favorable conditions for the growth of anaerobic ammonia oxidizing bacteria.

[0024] This invention presents a method for the rapid enrichment of anaerobic ammonia oxidizing bacteria through combined NLR and HRT regulation, which facilitates the rapid start-up of anaerobic ammonia oxidation reactors and provides a theoretical reference for the practical application of the Anammox process. Furthermore, it is simple to operate, convenient to manage, and has high processing efficiency, showing promising prospects for widespread application. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the device for enriching anaerobic ammonia-oxidizing bacteria according to the present invention.

[0026] Figure 2 The diagrams are pie charts showing the bacterial community structure, where (a) shows the bacterial community structure at the beginning of the experiment and (b) shows the bacterial community structure at the end of the experiment.

[0027] In the diagram, 1 is the inlet pump; 2 is the heating rod; 3 is the sampling port; 4 is the outlet; 5 is the electric stirrer; 6 is the pH and dissolved oxygen meter; 7 is the inlet tank; 8 is the outlet tank; and 9 is the PLC control box. Detailed Implementation

[0028] like Figure 1 As shown, the device for enriching anaerobic ammonia-oxidizing bacteria includes an inlet pump 1 for pumping water from the inlet tank 7 into the SBR reactor; a heating rod 2 inside the SBR reactor for regulating the water temperature; an outlet 4 connected to the outlet tank 8 on the SBR reactor; and an electric stirrer 5 on the SBR reactor to accelerate the reaction. A sampling port 3 is used for sampling and testing; a pH and dissolved oxygen meter 6 is used for online monitoring of pH and dissolved oxygen levels in the water; and a PLC control box 9 is used for overall control.

[0029] The method for enriching anaerobic ammonia-oxidizing bacteria in an SBR reactor using the above-described modified device comprises the following specific steps:

[0030] (1) Inoculate the SBR reactor with sludge

[0031] The experiment used an SBR reactor, a cylindrical plexiglass container with a main body effective volume of 5L, 300mm high, and 200mm in diameter. A row of sampling ports spaced 100mm apart was vertically arranged on the reactor wall for sampling and drainage. The reactor was equipped with a timer switch, a constant temperature heating rod, a solenoid valve, an influent pump, an electric stirrer, and pH and DO meters. Water entered through the top of the reactor and exited through the middle. The anaerobic ammonia oxidizing bacteria were commercially available; manufacturer: Shandong Luxing Environmental Protection Technology Co., Ltd.; model: LXHJ65; effective ingredient content: 90%; pH value: 6.5; brand: Luxing. These anaerobic ammonia oxidizing bacteria were inoculated into a sludge treatment tank of a wastewater treatment plant. The inoculated sludge in this experiment was taken from this sludge treatment tank, with an MLSS of 3300mg / L. The inoculation amount was one-fifth of the reactor volume, and the inoculated sludge contained a small amount of anaerobic ammonia oxidizing bacteria. The inoculated sludge can also be obtained by directly preparing commercially available anaerobic ammonia oxidizing bacteria.

[0032] (2) Composition and concentration of the culture medium

[0033] The test water used was artificially simulated wastewater. The influent substrate was provided by NH4Cl and NaNO2, and their concentrations were adjusted according to the operating results. No organic carbon source was added to the reactor during the entire test. The composition of the simulated wastewater is shown in Table 1.

[0034] Table 1 Simulated wastewater quality

[0035] Water distribution index Concentration (mg / L) <![CDATA[NH4 + -N]]> 30-40 <![CDATA[NO2 - -N]]> 30-40 <![CDATA[KH2PO4]]> 20 <![CDATA[MgSO4·7H2O]]> 350 <![CDATA[CaCl2·2H2O]]> 30 <![CDATA[NaHCO3]]> 500

[0036] Table 2 shows the trace element table. Trace elements I and II are added once a day, with the daily addition amount being 1 / 5000-1 / 20000 of the total weight of the water body. The composition and concentration of trace elements I and II are shown below:

[0037] Table 2 Trace Elements Table

[0038]

[0039]

[0040] (3) Operating parameters

[0041] The experiment employed an intermittent influent and effluent operation, maintaining a stable water temperature of 29-35℃, pH between 7.4-8.4, and dissolved oxygen concentration between 0-0.4 mg / L within the reactor. The reactor was strictly protected from light by a light-blocking cloth. The reactor operated for two cycles per day, with the operating time within each cycle varying according to the hydraulic retention time. Each cycle consisted of 15-25 minutes of influent, 4.5-8 hours of stirring and reaction, 60 minutes of settling, 15-25 minutes of effluent discharge, and the remaining time was idle. The effluent ratio was set at 1 / 2. No active sludge removal was performed during reactor operation.

[0042] (4) Results

[0043] ① Stage I (cycles 1-60), NH4 + -N and NO2 - The influent nitrogen concentrations were 30 mg / L and 40 mg / L, respectively, and the average nitrogen load was 0.24 kgN / (m³). 3 ·d), the hydraulic retention time is 8 hours. During this stage, the effluent concentration fluctuates significantly, possibly because the anaerobic ammonia-oxidizing bacteria are gradually adapting to the new environment. The NH4 concentration in the first 20 cycles... + -N and NO2 - -N removal rates decreased sharply, reaching minimums of 48.68% and 38.68%, with a total nitrogen removal rate of 38.05%. In the latter 20 cycles, as the anaerobic ammonia-oxidizing bacteria gradually adapted to the new environment, NH4+ removal decreased. + -N and NO2 - As the concentration of -N in the effluent gradually decreases, the removal rate gradually increases. NH4 + -N and NO2 - -N removal rates remained stable at approximately 80% and 70%, respectively, while total nitrogen removal rate remained stable at 65%, and NO3 removal rate remained stable at approximately 65%. - The slight increase in -N concentration may be due to the presence of some denitrifying bacteria in the reactor.

[0044] ② During Phase II (cycles 61-120), the average nitrogen load was 0.28 kg N / (m³). 3 ·d), due to the first stage NH4 + -N was almost completely degraded, NO2 - -N remains at approximately 10 mg / L, therefore, NH4 is adjusted in Phase II. + -N and NO2 - The influent and effluent concentrations of -N were both 30 mg / L, and the hydraulic retention time was 6 h. NH4 + -N and NO2 - -N effluent concentrations were relatively stable, with removal rates of approximately 95% and 98%, respectively, and total nitrogen removal rate reaching 80%. - An increase of 5-6 mg / L in -N concentration enhances the activity of anaerobic ammonia oxidizing bacteria.

[0045] ③ Stage III (cycles 121-180), during which NH4 + -N and NO2 - The influent nitrogen concentration remains at 30 mg / L, and the average nitrogen load is 0.32 kgN / (m³). 3 ·d) The hydraulic residence time is reduced to 5 hours. Due to the reduced hydraulic residence time, initially NH4 + -N and NO2 - -N effluent concentration fluctuates significantly, but the total nitrogen removal rate remains around 70%. After 10 cycles, NH4... + -N and NO2 - -N concentration in effluent is relatively stable, NH4+ + -N and NO2 - -N removal rate reached 95%, and total nitrogen removal rate reached 82%.

[0046] ④ Stage IV (cycles 181-240), during which NH4 + -N and NO2 - The influent nitrogen concentration was 40 mg / L, and the average nitrogen load was 0.41 kgN / (m³). 3 ·d), initially due to the increase in load, NH4 + -N and NO2 - -N removal rates were 80% and 75%, and total nitrogen removal rate was approximately 70%. The removal rate gradually increased with the number of cycles. + -N and NO2 - -N removal rate is around 85%, and total nitrogen removal rate is stable at 76%.

[0047] ⑤ Stage V (cycles 241-300), during this stage NH4 + -N and NO2 - The influent nitrogen concentration was 40 mg / L, and the average nitrogen load was 0.46 kgN / (m³). 3 ·d), further reduce the hydraulic retention time to 4.5h. After long-term acclimatization, NH4 + -N and NO2 - -N removal rate is about 85%, total nitrogen removal rate is stable at 78%, and NO3 in reactor - The average concentration of -N increased by 6.9 mg / L, and the activity of anaerobic ammonia oxidizing bacteria was enhanced, successfully achieving the enrichment of anaerobic ammonia oxidizing bacteria.

[0048] like Figure 2 As shown, after the experimental operation, the proportion of anaerobic ammonia oxidizing bacteria Candidatus-kuenenia increased from 2.5% at the beginning of the experiment to 17.9% at the end of the experiment.

[0049] (5) Convert the simulated wastewater into the actual wastewater that needs to be treated and operate it stably for a long time.

[0050] Based on Example 1 above, only the discharge water ratio was changed, and the experiment was conducted again. The results are shown in the table below:

[0051] Serial Number Discharge ratio Average total nitrogen removal rate 1 20％ 42.8％ 2 30％ 55.6％ 3 40％ 70.8％ 4 50％ 78.8％ 5 60％ 76.7％ 6 70％ 62.1％

[0052] The table above shows that using a drainage ratio of 40-60% yields better technical results.

[0053] Based on Example 1 above, only the stirring reaction time was changed, and the experiment was conducted again. The results are shown in the table below:

[0054] For stage I, NH4 + -N and NO2 - -N influent concentrations were 30 mg / L and 40 mg / L, respectively;

[0055] Serial Number Stirring reaction time Average total nitrogen removal rate 1 7h 52％ 2 7.5h 60.2％ 3 8h 65％ 4 8.5h 64.8％ 5 9h 65.4％

[0056] For stage II, NH4 + -N and NO2 - -N influent concentrations were 30 mg / L and 30 mg / L, respectively;

[0057]

[0058]

[0059] For stage III, NH4 + -N and NO2 - The influent concentrations of -N were 30 mg / L and 30 mg / L, respectively. Due to the prior acclimatization, the system gradually adapted to the changes in low HRT.

[0060] Serial Number Stirring reaction time Average total nitrogen removal rate 1 4h 73.4％ 2 4.5h 78.6％ 3 5h 82％ 4 5.5h 81.2％ 5 6h 83％

[0061] For stage IV, NH4 + -N and NO2 - -N influent concentrations were 40 mg / L and 40 mg / L, respectively.

[0062] Serial Number Stirring reaction time Average total nitrogen removal rate 1 4h 69.8％ 2 4.5h 73.4％ 3 5h 76.2％ 4 5.5h 64.8％ 5 6h 65.4％

[0063] For stage V, NH4 + -N and NO2 - -N influent concentrations were 40 mg / L and 40 mg / L, respectively.

[0064]

[0065]

[0066] The table above shows that the stirring reaction times for the five stages are 8h, 6h, 5h, 5h, and 4.5h, respectively, which have good technical effects.

[0067] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.

Claims

1. A method for rapid enrichment of anaerobic ammonia-oxidizing bacteria through combined regulation of NLR and HRT, characterized in that... Includes the following steps: (1) Selection of inoculated sludge and reactor, and setting of experimental parameters: Anaerobic ammonia-oxidizing bacteria flocculent sludge was inoculated into the SBR reactor. The reactor influent was artificial simulated wastewater. The changes in DO and pH within the reactor were monitored in real time using an online control system. Simultaneously, a heating rod was used to maintain the water temperature at 29-35℃; the pH was controlled between 7.4-8.4; and the dissolved oxygen concentration was controlled between 0-0.4 mg / L. The reactor was shielded from light by a light-blocking cloth. Trace elements I and II were added daily to the simulated wastewater. Trace element I consisted of Na2-EDTA·2H2O, 5000 mg / L; FeSO4·7H2O, 5000 mg / L. g / L; the components of trace element II are Na2-EDTA·2H2O, 15000 mg / L; ZnSO4·7H2O, 420 mg / L; CoCl2·6H2O, 240 mg / L; MnCl2·4H2O, 1000 mg / L; CuSO4·5H2O, 250 mg / L; NaMoO4·2H2O, 250 mg / L; NiCl2·6H2O, 200 mg / L; Na2SeO4, 250 mg / L; H3BO3, 15 mg / L; the daily addition of trace elements I and II is 1 / 5000-1 / 20000 of the total weight of the water body on that day; (2) The simulated wastewater was treated using an SBR reactor for several cycles. Each treatment cycle included: influent, reaction, sedimentation, effluent, and idle period, which were carried out in a loop. The SBR reactor operated in a total of five stages. Stage I was the activity recovery period. When the removal rates of ammonia nitrogen and nitrite reached 80%, the influent substrate concentration and hydraulic retention time were adjusted to proceed to Stage II. After the removal rates of ammonia nitrogen and nitrite reached a stable value, the hydraulic retention time was adjusted to increase the nitrogen load to proceed to Stage III. After the removal rates of ammonia nitrogen and nitrite reached a stable value, the influent substrate concentration was increased to increase the nitrogen load to proceed to Stage IV. In the first stage, after the removal rates of ammonia nitrogen and nitrite reach stable values, the hydraulic retention time is further reduced to increase the nitrogen load for the second stage. After the removal rates of ammonia nitrogen and nitrite reach stable values, this process continues until the removal rates of ammonia nitrogen and nitrite in the reactor are greater than 80% and the total nitrogen removal rate is greater than 75%. The SBR reactor operates for two cycles per day. In each cycle, the influent time is 15-25 minutes, the stirring reaction time is 4.5-8 hours, the settling time is 45-75 minutes, the drainage time is 15-25 minutes, and the remaining time is idle time. The drainage ratio is 40-60%. No sludge is actively discharged during the operation of the reactor. The reactor operated for a total of 300 cycles, corresponding to five stages; Phase I: Running cycles 1-60, NH4 + -N influent concentration is 30 mg / L, NO2 - The influent concentration of -N is 40 mg / L, and the hydraulic retention time at this stage is 8 hours. Phase II: Run cycles 61-120; NH4 + -N, NO2 - -N influent concentration was 30 mg / L, and hydraulic retention time was 6 h; Phase III: Run cycles 121-180; NH4 + -N, NO2 - The -N influent concentration was kept constant at 30 mg / L, and the hydraulic retention time was adjusted to 5 h. Phase IV: Run cycles 181-240; NH4 is adjusted during this phase. + -N, NO2 - The influent concentration of -N was 40 mg / L, and the hydraulic retention time remained unchanged at 5 h. Phase V: Run 241-300 cycles; keep the influent ammonia nitrogen concentration constant, and adjust the hydraulic retention time to 4.5h; (3) Convert the simulated wastewater into the actual wastewater that needs to be treated and operate it stably for a long time.

2. The method for rapid enrichment of anaerobic ammonia-oxidizing bacteria by combined regulation of NLR and HRT according to claim 1, characterized in that, The MLSS of the anaerobic ammonia oxidation flocculent sludge was 3300 mg / L, and the inoculum amount accounted for one-fifth of the SBR reactor volume.

3. The method for rapid enrichment of anaerobic ammonia-oxidizing bacteria by combined regulation of NLR and HRT according to claim 1, characterized in that, The simulated wastewater influent substrate was provided by NH4Cl and NaNO2, and the components of the simulated wastewater were: NH4Cl and NaNO2. + -N, 30-40 mg / L; NO2 - -N, 30-40mg / L; KH2PO4, 20mg / L; NaHCO3, 500mg / L.

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