A start-up method of an anaerobic ammonia oxidation process

Abstract

The present application relates to wastewater biological denitrification technical field, especially to an anaerobic ammonia oxidation process starting method, comprising the following steps: using the expanded granular sludge bed reactor as the starting device of anaerobic ammonia oxidation, under the condition that the wastewater contains ammonia nitrogen and nitrite, the ratio of the concentration of nitrite and ammonia nitrogen in wastewater is respectively 1.33, 2.00, 2.66, 1.33, 1.00, 1.00, 1.33 in stages dynamic control.The present application can provide sufficient electron acceptor to meet the needs of anaerobic ammonia oxidation process in the early stage of reactor starting, and the metabolic activity of anaerobic ammonia oxidation system is improved by regulation, so that the rapid start and long-term stable operation of anaerobic ammonia oxidation system are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater biological denitrification, in particular to a start-up method of an anaerobic ammonia oxidation process. BACKGROUND

[0002] Under the background of the national strategy of "carbon peak and carbon neutrality", energy-saving wastewater treatment technology has become a research hotspot and focus in the current environmental field. In recent years, how to economically and efficiently remove nitrogen pollutants from sewage wastewater to meet the increasingly stringent nitrogen emission standards has become a major environmental protection issue that needs to be addressed urgently. The new biological denitrification technology based on the anaerobic ammonia oxidation process has become an attractive resource-efficient solution.

[0003] Anaerobic ammonia oxidation refers to the process in which anaerobic ammonia oxidation bacteria oxidize ammonia nitrogen directly to nitrogen gas and generate a small amount of nitrate under anaerobic conditions with nitrite as the electron acceptor.

[0004]

[0005] This process has the advantages of high denitrification efficiency, 60% aeration quantity saving, no need for external organic carbon source, and 90% reduction in residual sludge production, and has obvious advantages and good application prospects in treating high-ammonia-nitrogen and low-carbon-nitrogen-ratio wastewater.

[0006] However, anaerobic ammonia oxidation bacteria grow slowly, with a doubling time of 11 days, and anaerobic ammonia oxidation bacteria only show activity when the cell density reaches a certain threshold (10 10 -10 11 Individuals / mL). This makes it difficult to cultivate and enrich them, and it takes at least several months. The long start-up period of the anaerobic ammonia oxidation process has become a major bottleneck hindering the application of the process in wastewater denitrification treatment. SUMMARY

[0007] The purpose of the present application is to provide a start-up method of an anaerobic ammonia oxidation process, which can provide sufficient electron acceptors to meet the needs of the anaerobic ammonia oxidation process in the early stage of reactor start-up, and regulate and improve the metabolic activity of the anaerobic ammonia oxidation system, thereby realizing the rapid start-up and long-term stable operation of the anaerobic ammonia oxidation system.

[0008] The present application provides a start-up method of an anaerobic ammonia oxidation process, comprising the following steps:

[0009] An expanded granular sludge bed reactor is used as the start-up device for anaerobic ammonia oxidation, and under the condition that the wastewater contains ammonia nitrogen and nitrite, the ratio of the nitrite and ammonia nitrogen concentrations in the wastewater is dynamically regulated in stages (stages I-VII) to be 1.33, 2.00, 2.66, 1.33, 1.00, 1.00, and 1.33, respectively.

[0010] The method of dynamically regulating the ratio of nitrite and ammonia nitrogen concentration in wastewater can overcome the negative influence of competition of denitrifying bacteria for nitrite at the initial stage of reactor start-up. Due to the increase of nitrite concentration in wastewater, the nitrite concentration obtained by unit weight of activated sludge in unit time is increased, which provides sufficient electron acceptor for anaerobic ammonia oxidation process and promotes the occurrence of anaerobic ammonia oxidation process, and is beneficial to the growth and enrichment of anaerobic ammonia oxidation bacteria.

[0011] Preferably, the wastewater is used for domestication of anaerobic ammonia oxidation bacteria, the ammonia nitrogen concentration in wastewater ranges from 30 to 60 mg / L, the nitrite concentration ranges from 30 to 80 mg / L, and a phosphorus source (3 mg / L) and a trace element concentrate solution (0.1% of the volume of wastewater) required for microbial growth are added.

[0012] Preferably, the DO value of the wastewater is 3-5 mg / L, the conditions for stable operation of the control equipment and the alkalinity required for maintaining the pH of the wastewater are determined according to the effluent ammonia nitrogen and nitrite concentration to determine the time for entering the next stage.

[0013] Preferably, the ammonia nitrogen concentration of the wastewater is provided by NH4Cl, the nitrite concentration is provided by NaNO2, the phosphorus source is provided by KH2PO4, and the alkalinity is provided by NaHCO3.

[0014] Preferably, the anaerobic ammonia oxidation reaction system is placed in an anaerobic environment at 35±1℃, and the pH of the wastewater is maintained at 7-8 at all times.

[0015] Preferably, the trace element concentrate solution is prepared by dissolving 0.5g H3BO3, 0.5g ZnCl2, 0.5g (NH4)6Mo7O 24 4H2O, 0.5g NiCl·6H2O, 0.5g AlCl3·6H2O, 0.5g CoCl2·6H2O, 0.5g CuSO4·5H2O, 1.6g FeCl3, 2.7g FeCl3·6H2O, 1g MnCl2·4H2O, 5g MgSO4·7H2O, and 5mL 37wt% HCl solution in 1000mL water.

[0016] Preferably, the expanded granular sludge bed reactor comprises a water inlet system, a reaction chamber, a three-phase separator, and a three-phase separation zone, the bottom end of the reaction chamber is provided with a water inlet pipe connected to the water inlet system, the reaction chamber is connected to the three-phase separation zone through a funnel-shaped gradually expanding pipe, the inverted funnel-shaped three-phase separator is connected to the external environment through a gas guide pipe, the inner wall of the three-phase separation zone is provided with a protruding overflow port connected to a water outlet pipe, the top and bottom of the inner wall of the reaction chamber are provided with sampling pipes, and the bottom of the reaction chamber is provided with a perforated plate.

[0017] Preferably, the diameter of the multi-well plate hole is 2 mm, which is beneficial to uniform water distribution and prevents granular sludge from falling and blocking the water inlet pipe.

[0018] Preferably, the effective volume of the reaction chamber is 6 L, and the height-diameter ratio is 10:1.

[0019] Preferably, the sludge concentration (MLSS) inoculated in the expanded granular sludge bed reactor is 44 g / L, the hydraulic retention time is 24 h, and the reflux ratio is 10:1; the inoculated sludge is from the anaerobic tank sludge of a dyeing and printing industrial park wastewater treatment plant.

[0020] Through the above preferred scheme, the enriched bacterial community is obtained by 16S rRNA gene sequencing technology.

[0021] The beneficial effects of the present application are:

[0022] The present application develops an anaerobic ammonia oxidation enhanced start-up method based on chemometrics regulation, which can provide sufficient electron acceptors to meet the needs of the anaerobic ammonia oxidation process in the early stage of reactor start-up, and provide a basic guarantee for the growth and enrichment of anaerobic ammonia oxidation bacteria.

[0023] The method of dynamically regulating the ratio of nitrite and ammonia nitrogen concentration in wastewater can ensure that the activated sludge per unit weight obtains sufficient nitrite per unit time, providing sufficient electron acceptors for the anaerobic ammonia oxidation process and promoting the occurrence of the anaerobic ammonia oxidation process.

[0024] In addition, by dynamically regulating the ratio of nitrite and ammonia nitrogen concentration in wastewater, the relative abundance of denitrifying bacteria can be significantly reduced, and as the anaerobic ammonia oxidation bacteria are cultured and domesticated, the anaerobic ammonia oxidation effect in the reactor is obvious. In the 71th stage, the relative abundance of Candidatus Brocadia is as high as 20.31%, and the average removal rates of ammonia nitrogen and nitrite in wastewater are 93.81% and 95.21%, respectively. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the following specific embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0026] Figure 1 The experimental device diagram of the present application;

[0027] Figure 2 The change of denitrification performance of the anaerobic ammonia oxidation start-up device;

[0028] Figure 3 Total nitrogen removal rate of the anammox start-up device;

[0029] Figure 4 Microbial community structure change (phylum level) of the anammox start-up device;

[0030] Figure 5 Microbial community structure change (genus level) of the anammox start-up device;

[0031] Figure 6 Relative abundance change of Candidatus Compet ibacter and Candidatus Brocadia in the anammox start-up device.

[0032] Explanation of reference signs: 1 - reaction chamber, 2 - three-phase separator, 3 - three-phase separation zone, 4 - water inlet pipe, 5 - gradually expanding pipe, 6 - air guide pipe, 7 - overflow port, 8 - water outlet pipe, 9 - sampling pipe, 10 - multi-hole plate. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the present application. Unless otherwise defined, 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 application belongs.

[0034] It should be noted that the terms used herein are only intended to describe specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form also includes the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0035] The technical solutions of the present application will be described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0036] The present applicant found in the research and exploration that denitrifying bacteria can utilize residual organic matter or dead microorganisms in the reactor for endogenous denitrification to participate in the reduction of nitrite at the initial stage of reactor start-up, which leads to rapid consumption of nitrite in the reactor, hindering the occurrence of anammox process.

[0037] Dynamic regulation of the ratio of nitrite and ammonia concentration in wastewater can overcome the negative effects of competition for nitrite by denitrifying bacteria at the initial stage of reactor start-up. With the increase of nitrite concentration in wastewater, the nitrite concentration obtained by unit weight of activated sludge in unit time is increased, which provides sufficient electron acceptor for anaerobic ammonia oxidation process and promotes the occurrence of anaerobic ammonia oxidation process, thus being beneficial to the growth and enrichment of anaerobic ammonia oxidation bacteria.

[0038] Preparation Example

[0039] A preparation step of a trace element concentrate solution: 0.5 g of H3BO3, 0.5 g of ZnCl2, 0.5 g of (NH4)6Mo7O 24 4H2O, 0.5 g of NiCl·6H2O, 0.5 g of AlCl3·6H2O, 0.5 g of CoCl2·6H2O, 0.5 g of CuSO4·5H2O, 1.6 g of FeCl3, 2.7 g of FeCl3·6H2O, 1 g of MnCl2·4H2O, 5 g of MgSO4·7H2O, and 5 mL of a 37 wt% HCl solution are dissolved in 1000 mL of water.

[0040] The domestication of the anaerobic ammonia oxidation bacterial community is performed using artificially prepared wastewater, the ammonia nitrogen concentration of the wastewater substrate is provided by NH4Cl, the nitrite concentration is provided by NaNO2, the phosphorus source is provided by KH2PO4, the alkalinity is provided by NaHCO3, and 0.1% of the volume of the wastewater is added with a trace element concentrate solution. The DO value of the wastewater is 3-5 mg / L during the experimental period.

[0041] Embodiment

[0042] A start-up method of an anaerobic ammonia oxidation process, which uses an expanded granular sludge bed (EGSB) reactor as a start-up device for anaerobic ammonia oxidation, comprising a water inlet system, a reaction chamber 1, a three-phase separator 2, and a three-phase separation zone 3, the bottom end of the reaction chamber 1 is provided with a water inlet pipe 4 connected to the water inlet system, the reaction chamber 1 is connected to the three-phase separation zone 3 through a funnel-shaped gradually expanding pipe 5, the inverted funnel-shaped three-phase separator 1 is connected to the external environment through a gas guide pipe 6, a protruding overflow port 7 is provided on the inner wall of the three-phase separation zone 3 to communicate with a water outlet pipe 8, sampling pipes 9 are provided on the top and bottom of the inner wall of the reaction chamber 1, and a perforated plate 10 with a diameter of 2 mm is provided at the bottom of the reaction chamber 1, which is beneficial to uniform water distribution and prevents granular sludge from falling and blocking the water inlet path, for details, see the attached drawings. Figure 1 .

[0043] The conditions required for starting the control device are controlled, the inoculated sludge concentration (MLSS) is 44 g / L, the temperature condition is controlled at 35±1℃, the hydraulic retention time (HRT) is controlled at 24 h, the reflux ratio is 10:1, and the inoculated sludge comes from the anaerobic tank sludge of a dyeing and printing industrial park wastewater treatment plant.

[0044] The top three phyla of the inoculated sludge were Proteobacteria, Chloroflexi and Syntrophiaceae. No anaerobic ammonia oxidation species was detected at the genus level, and the main denitrifying bacteria were Candidatus Competibacter, with a relative abundance of 40.27%.

[0045] Under the condition that the wastewater contains ammonia nitrogen and nitrite, the ratio of the concentrations of nitrite and ammonia nitrogen in the wastewater is dynamically regulated in stages (stages I-VII) as 1.33, 2.00, 2.66, 1.33, 1.00, 1.00 and 1.33, as shown in Table 1, which is the water quality characteristics of the wastewater during the experiment.

[0046] Table 1

[0047]

[0048] The treatment method specifically comprises the following steps:

[0049] In stages I-III, the conditions for stable operation of the equipment and the alkalinity required for maintaining the pH of the wastewater are controlled, artificial wastewater is used, the influent conditions of the wastewater are controlled as follows: the ammonia nitrogen concentration is 30 mg / L, the nitrite concentration is 40-80 mg / L, a phosphorus source (3 mg / L) required for microbial growth and a trace element concentrate solution of 0.1% of the volume of the wastewater are added, the ratio of the concentrations of nitrite and ammonia nitrogen in the wastewater is dynamically regulated as 1.33, 2.00 and 2.66, the running time is from the 1st day to the 60th day, and the nitrite concentration in the effluent is used as an index. When the nitrite removal rate in the wastewater is more than 99% and the ammonia nitrogen in the wastewater is almost not removed, the nitrite concentration in the wastewater is further increased, i.e., the ratio of the concentrations of nitrite and ammonia nitrogen in the wastewater is further increased.

[0050] In stages IV-V, because the average nitrite removal rate at the end of the previous stage decreases from 99.04% to 73.71%, the average nitrite concentration in the effluent increases to 21.02 mg / L, which is higher than the inhibition threshold of 5 mg / L. Therefore, in stage IV, the other operating conditions are not changed, the ammonia nitrogen concentration in the wastewater is maintained unchanged, and the nitrite concentration in the wastewater is reduced to 40 mg / L. However, the nitrite in the wastewater in this stage is still not completely removed, and the average nitrite removal rate is only maintained at 73.76%. In order to avoid the continuous inhibition of the residual nitrite in the reactor on the anaerobic ammonia oxidation bacteria, in stage V, the nitrite concentration in the wastewater is further reduced to 30 mg / L, i.e., the ratio of the concentrations of nitrite and ammonia nitrogen in the wastewater in stages IV and V is 1.33 and 1.00, respectively. The running time of stages IV-V is from the 61st day to the 152nd day.

[0051] In the phase VI-VII, the ratio of nitrite removal and ammonia removal in the reactor decreased to 1.49, in order to keep the ratio of ammonia and nitrite in the wastewater equal to the stoichiometric ratio of ANAMMOX reaction (1.32), the concentration of ammonia and nitrite in the wastewater were further increased to 60 and 80 mg / L in the phase VII, the ratio of nitrite removal and ammonia removal in the reactor decreased to 1.35, and the average removal rate of ammonia and nitrite in the wastewater reached 93.81% and 95.21% respectively, which indicated that the ANAMMOX process in the reactor was successfully started, and the running time of the phase VI-VII was from the 153th day to the 222th day.

[0052] The treatment method provided sufficient electron acceptor to meet the needs of ANAMMOX process at the initial stage of reactor start-up, weakened the negative effects of denitrifying bacteria competing for nitrite when activated sludge was used as inoculum to start the ANAMMOX process, and provided a basic guarantee for the efficient operation of the ANAMMOX reaction system.

[0053] Effect verification:

[0054] I. Change of total nitrogen removal rate: Through the method of dynamically adjusting the ratio of nitrite and ammonia in the wastewater, the total nitrogen removal rate of the wastewater showed a trend of first increasing and then decreasing in the phase I-III, mainly because a large number of denitrifying bacteria occupied the dominant ecological niche at the initial stage of reactor start-up, the denitrification process in the reactor was the main nitrogen removal path, and the nitrite in the wastewater was mainly removed through the endogenous denitrification pathway, thereby improving the total nitrogen removal rate of the wastewater. In the phase IV-V, the total nitrogen removal rate of the wastewater decreased significantly, mainly because the activity of denitrifying bacteria in the reactor was significantly inhibited, while the ANAMMOX process in the reactor had not occurred or had not become the main denitrification pathway, thereby leading to poor removal effect of nitrogen pollutants in the wastewater. In the phase VI-VII, the total nitrogen removal rate of the wastewater improved significantly, reaching the optimal state in the running process, mainly because the activity of ANAMMOX bacteria in the reactor was significantly improved, and the average removal rate of ammonia and nitrite in the wastewater reached 93.81% and 95.21% respectively in the phase VII, details are shown in the following table. Figures 2-3 , Figure 2 I-VII represent the 1st-7th phase, EffNH4 + -N represents the effluent ammonia concentration, EffNO2 -- N represents effluent nitrite concentration, EffN03 - - N represents effluent nitrate concentration, NH4 + - N Removal rate represents ammonia nitrogen removal rate, NO2 - - N Removal rate represents nitrite removal rate.

[0055] II. Changes in relative abundance of Candidatus Competibacter and Candidatus Brocadia: During the operation of the reactor, as the residual organic matter in the reactor was consumed, the relative abundance of Candidatus Competibacter decreased significantly, from 40.27% to 0.88%; no anaerobic ammonia oxidation species was detected in the inoculated sludge, but as the anaerobic ammonia oxidation bacteria were cultured and domesticated, the effect of anaerobic ammonia oxidation in the reactor was obvious, and the relative abundance of the phylum-level species of the anaerobic ammonia oxidation bacteria, i.e., the relative abundance of the phylum Chloroflexi, increased significantly; the relative abundance of the genus-level species of the anaerobic ammonia oxidation bacteria, i.e., Candidatus Brocadia, increased from 0.08% in the Vth stage to 20.31% in the VIIth stage, details of which are shown in the following table: Figures 4-6 .

[0056] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for starting up an anaerobic ammonia oxidation process, characterized in that, The method comprises the following steps: The anaerobic ammonium oxidation is started by using an expanded granular sludge bed reactor, and under the condition that the wastewater contains ammonia nitrogen and nitrite, the ratio of the concentration of nitrite to the concentration of ammonia nitrogen in the wastewater is dynamically regulated in stages to be 1.33, 2.00, 2.66, 1.33, 1.00, 1.00 and 1.33, the wastewater is used for domestication of the anaerobic ammonium oxidation bacteria, the concentration of ammonia nitrogen in the wastewater ranges from 30 to 60 mg / L, the concentration of nitrite ranges from 30 to 80 mg / L, 3 mg / L of a phosphorus source required for microbial growth and 0.1% of trace element concentrate in the volume of the wastewater are added, the DO value of the wastewater is 3-5 mg / L, the conditions required for stable operation of the equipment and the alkalinity required for maintaining the pH of the wastewater are controlled, the time for entering the next stage is determined according to the concentration of ammonia nitrogen and nitrite in the effluent, the concentration of ammonia nitrogen in the wastewater is provided by NH4Cl, the concentration of nitrite is provided by NaNO2, the phosphorus source is provided by KH2PO4, and the alkalinity is provided by NaHCO3, the anaerobic ammonium oxidation reaction system is placed in an anaerobic environment at 35±1℃, and the pH of the wastewater is maintained at 7-8.

2. The start-up method of an anaerobic ammonia oxidation process according to claim 1, characterized in that, The microelement concentrate preparation method is: 0.5g H3BO3, 0.5g ZnCl2, 0.5g(NH4)6Mo7O 24 ·4H2O, 0.5g NiCl·6H2O, 0.5g AlCl3·6H2O, 0.5g CoCl2·6H2O, 0.5g CuSO4·5H2O, 1.6g FeCl3, 2.7g FeCl3·6H2O, 1g MnCl2·4H2O, 5g MgSO4·7H2O, 5mL 37wt% HCl solution is dissolved in 1000mL water.

3. The start-up method of an anaerobic ammonia oxidation process according to claim 1, characterized in that, The expanded granular sludge bed reactor comprises a water inlet system, a reaction chamber, a three-phase separator and a three-phase separation zone, the bottom end of the reaction chamber is provided with a water inlet pipe connected to the water inlet system, the reaction chamber is connected to the three-phase separation zone through a funnel-shaped gradually expanding pipe, the inverted funnel-shaped three-phase separator is connected to the external environment through a gas guide pipe, the inner wall of the three-phase separation zone is provided with a protruding overflow port connected to a water outlet pipe, the top and bottom of the inner wall of the reaction chamber are provided with sampling pipes, and the bottom of the reaction chamber is provided with a perforated plate.

4. The start-up method of an anaerobic ammonia oxidation process according to claim 3, characterized in that, The diameter of the holes of the perforated plate is 2 mm, which is beneficial to uniform water distribution and prevents the granular sludge from falling and blocking the water inlet pipe.

5. The start-up method of an anaerobic ammonia oxidation process according to claim 3, characterized in that, The effective volume of the reaction chamber is 6 L, and the height-diameter ratio is 10:

1.

6. The start-up method of an anaerobic ammonia oxidation process according to claim 1, characterized in that, The sludge concentration (MLSS) of the expanded granular sludge bed reactor is 44 g / L, the hydraulic retention time is 24 h, and the reflux ratio is 10:1.

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