A method for enhancing anaerobic ammonium oxidation performance using magnetite as a core

Abstract

The present invention relates to a method for enhancing the performance of anaerobic ammonia oxidation using magnetite as a core, characterized in that the method comprises the following steps: Step 1, starting an upflow anaerobic sludge blanket reactor and monitoring the denitrification effect of anaerobic ammonia oxidizing bacteria; Step 2, when the denitrification effect of the anaerobic ammonia oxidation reaches a preset index, adding magnetite with a micron-sized particle size to the upflow anaerobic sludge blanket reactor to achieve continued cultivation of the anaerobic ammonia oxidizing bacteria. The present invention adds micron-sized magnetite to a UASB reactor, and the bacterial community secretes a large amount of extracellular polymers. The extracellular polymers and iron core increase the particle size of the bacterial community, and the anaerobic ammonia oxidation activity is increased by 39%. The present invention has a simple process, high feasibility, easy-to-buy materials, and is non-toxic and harmless to the environment, and is convenient for application in sewage treatment projects.

Description

Technical Field

[0001] The present invention relates to the field of sewage treatment, and more specifically, to a method for enhancing the anaerobic ammonia oxidation performance using magnetite as a core. Background Art

[0002] At present, anaerobic ammonium oxidation (Anammox) technology uses NO2 - -N is used as an electron acceptor and does not require additional carbon source and aeration, and has been widely used in sewage treatment worldwide. However, anaerobic ammonium oxidizing bacteria grow slowly, and the development of methods to optimize the operation of anaerobic ammonium oxidizing reactors and promote the granulation of anaerobic ammonium oxidizing bacteria is still a research hotspot.

[0003] The crystal nucleus theory is one of the important theories of anaerobic granule formation. Researchers promote the formation of anaerobic ammonium-oxidizing bacteria granules by adding hydroxyapatite. Hydroxyapatite can exist in the granules as a stable core, but the high concentration of phosphate ions added can easily cause secondary pollution to the water body and is not conducive to the activity of anaerobic ammonium-oxidizing bacteria. In the prior art, there is no more environmentally friendly method that is different from hydroxyapatite and can promote the granulation of anaerobic ammonium-oxidizing bacteria.

[0004] On the other hand, iron is widely distributed in anaerobic ammonium-oxidizing bacteria and plays an important role in the growth of anaerobic ammonium-oxidizing bacteria cells and the formation of heme. Researchers have found that the denitrification performance of the anaerobic ammonium-oxidizing reactor has been significantly improved by exogenous addition of divalent iron ions and trivalent iron ions. Iron-based materials have also been shown to be more helpful to the stability of anaerobic ammonium-oxidizing particle formation than non-iron-based materials. In the prior art, the use of nano-magnetite and nano-zero-valent iron can significantly promote the agglomeration and granulation of anaerobic ammonium-oxidizing bacteria, but there are problems with the cumbersome steps of nanoparticle synthesis, easy deterioration and unstable effects.

[0005] In view of the above problems, there is an urgent need for a method to enhance the performance of oxygen-ammonia oxidation through suitable iron-based materials. Summary of the invention

[0006] In order to solve the deficiencies in the prior art, the present invention provides a method for enhancing the anaerobic ammonia oxidation performance using magnetite as a core, by adding micron-sized magnetite to an upflow anaerobic sludge blanket reactor to enhance the oxygen ammonia oxidation performance.

[0007] The present invention adopts the following technical solution.

[0008] The first aspect of the present invention relates to a method for enhancing the performance of anaerobic ammonium oxidation using magnetite as a core, the method comprising the following steps: step 1, starting an upflow anaerobic sludge blanket reactor and monitoring the denitrification effect of anaerobic ammonium oxidizing bacteria; step 2, when the anaerobic ammonium oxidation denitrification effect reaches a preset index, adding magnetite with a micron-sized particle size to the upflow anaerobic sludge blanket reactor to achieve continued cultivation of the anaerobic ammonium oxidizing bacteria.

[0009] Preferably, the particle size of the magnetite is 10-20 μm; and the magnetite is dissolved in the wastewater with the concentration of ammonium nitrogen and nitrite nitrogen being 50 mg / L respectively at a content of 1 g / L.

[0010] Preferably, the volume of the upflow anaerobic sludge blanket reactor is 5L; starting the upflow anaerobic sludge blanket reactor also includes: inoculating the upflow anaerobic sludge with a VSS of 1000-1100 mg / L pre-acclimated anaerobic ammonia oxidation sludge into the upflow anaerobic sludge blanket reactor, introducing wastewater with ammonium nitrogen and nitrite nitrogen concentrations of 50 mg / L respectively, and purging a mixed gas with a volume ratio of 95% nitrogen and 5% carbon dioxide.

[0011] Preferably, the preset indicators are the startup time of the upflow anaerobic sludge blanket reactor and the denitrification efficiency index of the upflow anaerobic sludge blanket reactor.

[0012] Preferably, the preset indicator is that the startup of the upflow anaerobic sludge blanket reactor reaches 14 days or the ammonia nitrogen removal rate in the upflow anaerobic sludge blanket reactor reaches 90%.

[0013] Preferably, the concentrations of ammonium nitrogen and nitrite nitrogen in the wastewater are preferentially adjusted, and then the hydraulic retention time of the reactor is adjusted; when the startup time of the reactor reaches 90 days, the concentrations of ammonium nitrogen and nitrite nitrogen in the wastewater are adjusted to 200 mg / L, and the hydraulic retention time is adjusted to 12 hours.

[0014] Preferably, the method further comprises: using a control group, adding ferrous sulfate of the same concentration as magnetite to replace the magnetite of micron-sized particles, thereby achieving the cultivation of anaerobic ammonia-oxidizing bacteria.

[0015] Preferably, the method further comprises: after the cultivation of the anaerobic ammonium-oxidizing bacteria is completed, the anaerobic ammonium-oxidizing sludge is placed in an anaerobic state for shaking, and the sludge is sampled every 1 to 2 hours, and the supernatant is filtered through a 0.45 μm filter membrane for three nitrogen determination.

[0016] Preferably, the method further comprises: measuring the particle size of the bacterial flora in the sludge on the 0th day, the 57th day, the 71st day and the 95th day using a laser diffraction particle size analyzer at a refractive index of 1.53.

[0017] The beneficial effect of the present invention is that, compared with the prior art, the method of enhancing the anaerobic ammonia oxidation performance using magnetite as a core in the present invention can enhance the ammonia oxidation performance of anaerobic ammonia oxidizing bacteria by adding micron-sized magnetite to an upflow anaerobic sludge blanket reactor. From the test results, it can be seen that the method of the present invention further improves the activity of anaerobic ammonia oxidizing bacteria, maintains reaction stability and promotes granulation.

[0018] The present invention adds micron-sized magnetite in the UASB reactor, and the bacterial community secretes a large amount of extracellular polymers. The extracellular polymers and iron cores increase the particle size of the bacterial community, and the anaerobic ammonia oxidation activity is increased by 39%. The present invention has a simple process, high feasibility, easy-to-buy materials, is non-toxic and harmless to the environment, and is easy to apply in sewage treatment projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of a reaction device in a method for enhancing anaerobic ammonia oxidation performance using magnetite as a core of the present invention;

[0020] Reference numerals:

[0021] 1-Water bucket,

[0022] 2-Upflow anaerobic sludge blanket reactor,

[0023] 3- Water inlet pump,

[0024] 4-Water inlet bucket,

[0025] 5- Reflux pump,

[0026] 6-Circulation pump,

[0027] 7- Water bath;

[0028] Figure 2 It is a schematic diagram of the nitrogen removal process in anaerobic ammonium oxidation sludge in a method for enhancing anaerobic ammonium oxidation performance using magnetite as a core of the present invention;

[0029] Figure 3 It is a schematic diagram of the microstructure of the bacterial flora of the control group and the experimental group in a method for enhancing the anaerobic ammonium oxidation performance using magnetite as a core of the present invention;

[0030] Figure 4 It is a schematic diagram of the process of EPS secretion by the microflora of the control group and the experimental group in a method for enhancing the anaerobic ammonium oxidation performance using magnetite as a core of the present invention;

[0031] Figure 5 This is a diagram showing changes in the bacterial community structure and nitrogen cycle functional genes in the entire sample of the control group and the experimental group in a method for enhancing anaerobic ammonia oxidation performance using magnetite as a core of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in the present invention are only embodiments of a part of the present invention, not all embodiments. Based on the spirit of the present invention, all other embodiments not recorded in the present invention obtained by ordinary technicians in this field according to the embodiments recorded in the present invention without making creative work should belong to the protection scope of the present invention.

[0033] The invention relates to a method for enhancing anaerobic ammonia oxidation performance by taking magnetite as a core. The method comprises step 1 and step 2.

[0034] Step 1: Start the upflow anaerobic sludge blanket reactor and monitor the denitrification effect of anaerobic ammonium oxidizing bacteria.

[0035] It should be noted that the method provided by the present invention improves the denitrification performance of anaerobic ammonia-oxidizing bacteria by operating an upflow anaerobic sludge bed (UASB) reactor and adding micron-sized magnetite.

[0036] Figure 1 The figure is a schematic diagram of a reaction device in a method for enhancing the anaerobic ammonium oxidation performance using magnetite as a core according to the present invention. Figure 1 As shown, when the reactor is working, the sewage enters the bottom of the reactor through uniform water distribution, and the sewage passes through the anaerobic sludge blanket reactor from bottom to top. A high-concentration, high-activity sludge layer can be set at the bottom of the reactor, and the three-phase separation of gas, liquid and solid can be completed through the three-phase separator set at the top of the reactor.

[0037] Preferably, the volume of the upflow anaerobic sludge blanket reactor is 5L; starting the upflow anaerobic sludge blanket reactor also includes: inoculating the upflow anaerobic sludge with a VSS of 1000-1100 mg / L pre-acclimated anaerobic ammonia oxidation sludge into the upflow anaerobic sludge blanket reactor, introducing wastewater with ammonium nitrogen and nitrite nitrogen concentrations of 50 mg / L respectively, and purging a mixed gas with a volume ratio of 95% nitrogen and 5% carbon dioxide.

[0038] The present invention adopts Figure 1 The culture process of anaerobic ammonia oxidizing bacteria in sludge is realized in the above way. The reactor is always operated at a temperature of 37±1℃, and a water bath is used to control the stability of the reactor temperature. At the same time, the pH of the reactor is maintained between 7.5-8.0. The whole process is cultured under light-proof conditions.

[0039] Step 2: When the anaerobic ammonium oxidation denitrification effect reaches a preset index, magnetite with a micron-sized particle size is added to the upflow anaerobic sludge blanket reactor to achieve continued cultivation of the anaerobic ammonium oxidizing bacteria.

[0040] Preferably, the preset indicators are the startup time of the upflow anaerobic sludge blanket reactor and the denitrification efficiency index of the upflow anaerobic sludge blanket reactor.

[0041] According to the usual cultivation method of the upflow anaerobic sludge blanket reactor for anaerobic ammonia oxidation sludge, it is possible to further add magnetite when the denitrification effect in the sludge remains relatively stable. The startup duration here can be set according to experience. Of course, the present invention also supports the use of various objective indicators to achieve the evaluation of the denitrification efficiency. For example, the Nessler spectrophotometry method in the prior art can be used to determine the content of ammonium nitrogen, and the N-(1-naphthyl)-ethylenediamine spectrophotometry method can also be used to determine the content of nitrite nitrogen, and so on.

[0042] In one embodiment of the present invention, the preset index is that the startup of the upflow anaerobic sludge blanket reactor reaches 14 days or the ammonia nitrogen removal rate in the upflow anaerobic sludge blanket reactor reaches 90%. On this basis, magnetite with a micron-sized particle size is added to the upflow anaerobic sludge blanket reactor, and the influent nitrogen concentration, the hydraulic retention time of the reactor and other indicators are jointly adjusted and continuously adjusted.

[0043] Preferably, the method further comprises: using a control group, adding ferrous sulfate of the same concentration as magnetite to replace the magnetite of micron-sized particles, thereby achieving the cultivation of anaerobic ammonia-oxidizing bacteria.

[0044] In the present invention, a control group was selected to observe the excellent characteristics of micron-sized magnetite in enhancing the anaerobic ammonium oxidation performance. In addition, in order to eliminate the influence of the iron element itself on the enrichment of anaerobic ammonium oxidizing bacteria, the present invention also added ferrous sulfate of the same concentration to the control group.

[0045] Specifically, the particle size of magnetite is 10 to 20 μm; and the magnetite is dissolved in wastewater with an ammonium nitrogen concentration of 50 mg / L and a nitrite nitrogen concentration of 50 mg / L at a content of 1 g / L.

[0046] The particle size of the magnetite with the best bacterial aggregation effect used in the present invention is between 10 and 20 μm. In addition, the present invention refers to the content of the prior art and selects magnetite with a content of 1 g / L so that the total nitrogen removal rate is maintained at more than 95% after 40 days.

[0047] It should be noted that the size of anaerobic ammonium oxidizing cells is between 0.8-1.2μm, and nano-magnetite can be attached to the surface of anaerobic ammonium oxidizing bacteria to promote the granulation of anaerobic ammonium oxidizing bacteria. Unlike nano-sized magnetite, in the present invention, it is confirmed that micron-sized magnetite can be used as the core of anaerobic ammonium oxidizing bacteria, and anaerobic ammonium oxidizing bacteria of 0.8-1.2μm size can be adsorbed on the surface of magnetite. This process can fully promote the formation of anaerobic ammonium oxidizing sludge granulation, while fully avoiding the instability of nanomaterials.

[0048] In the prior art, magnetite with a diameter of 45 to 75 μm was used as a carrier to run an SBR (Sequencing Batch Reactor Activated Sludge Process) reactor. It was found that magnetite promoted the granulation of anaerobic ammonium oxidizing bacteria, but had no significant effect on improving performance. After running three times, magnetite with a diameter of 100 μm only increased the anaerobic ammonium oxidation activity by 5.9%, and sometimes even had an inhibitory effect.

[0049] To this end, the particle size of the selected magnetite is reasonably improved in the present invention. In one embodiment of the present invention, the magnetite material comes from Beijing Belo Biotechnology Co., Ltd. The magnetite raw material is easy to purchase, low in cost, and non-toxic and harmless to the environment. By reasonably selecting various indicators in the reaction process, the present invention uses 10-20μm magnetite as the core to achieve the aggregation of anaerobic ammonia oxidation bacteria in anaerobic ammonia oxidation sludge, promote the secretion of a large amount of extracellular polymers by the bacteria and increase the particle size of sludge particles. After adding magnetite, the enzyme activity required for anaerobic ammonia oxidation sludge in the anaerobic ammonia oxidation reaction process is relatively improved. After testing, it was found that the total nitrogen removal rate was increased by 39%.

[0050] Preferably, the concentrations of ammonium nitrogen and nitrite nitrogen in the wastewater are preferentially adjusted, and then the hydraulic retention time of the reactor is adjusted; when the startup time of the reactor reaches 90 days, the concentrations of ammonium nitrogen and nitrite nitrogen in the wastewater are adjusted to 200 mg / L, and the hydraulic retention time is adjusted to 12 hours.

[0051] In the method of the present invention, before and after the addition of magnetite, along with the enrichment degree of the bacterial flora, the method can also adjust the concentration of ammonium nitrogen and nitrite nitrogen in the wastewater and the hydraulic retention time in the reactor in real time according to the progress of the test. When the start-up time of the reactor reaches between 90 days and 95 days when the test is about to end, the concentration of ammonium nitrogen and nitrite nitrogen can be further increased, and the hydraulic retention time can be further shortened.

[0052] Preferably, the method further comprises: after the cultivation of the anaerobic ammonium-oxidizing bacteria is completed, the anaerobic ammonium-oxidizing sludge is placed in an anaerobic state for shaking, and the sludge is sampled every 1 to 2 hours, and the sludge is filtered through a 0.45 μm filter membrane to perform three nitrogen determinations on the supernatant obtained after filtration.

[0053] It should be noted that the method for determining the three nitrogens in the present invention is achieved by taking out the wet sludge from the reactor after the test. Specifically, 4 g of wet sludge can be evenly weighed in the mixed R1 and R2 reactors for activity testing. The activity experiment was carried out in a 500 mL serum bottle, inoculated with NH4 + -N and NO2 - -N each 50mg / L anaerobic ammonium oxidation medium, with a volume ratio of 95% N2 and 5% CO2 aeration for 30 minutes, so as to maintain the original anaerobic conditions of the sludge in the reactor. During the test, a number of biological replicates can be set up to 3, and all collected samples are placed in a constant temperature shaker at 37°C and a speed of 150rpm for the experiment. Sampling is carried out with a syringe every 1 to 2 hours, and the supernatant is filtered through a 0.45 micron filter membrane for later three nitrogen determination.

[0054] Figure 2 Schematic diagram of the nitrogen removal process in anaerobic ammonium oxidation sludge in a method of enhancing anaerobic ammonium oxidation performance using magnetite as a core of the present invention. Figure 2 As shown in the figure, the contents of various nitrogen-containing components in the control group R1 and the experimental group R2 changed within 5 hours. (a) NH4 + -N concentration, (b) NO2 - -N concentration, NO3 in (c) - The concentration of -N gradually decreased with the extension of the test time, and the effect of R2 was significantly better than that of R1. Therefore, the total nitrogen removal rate in (d) also increased significantly with the increase of the test time. Within 0 to 2 hours, the nitrogen removal rate was generally high, and remained relatively balanced after 2 hours. The nitrogen removal rate of R2 was maintained at 15g / m 3 At 3 h, the total nitrogen removal rate of the experimental group was significantly higher than that of the control group, and at 5 h, the total nitrogen removal rate reached 16.28 g·m -3 ·h -1 , while the control group was only 11.82 g·m -3 ·h -1 , the denitrification activity was significantly increased by 39%. The results show that the addition of magnetite significantly increased the denitrification rate of anaerobic ammonium oxidation sludge. In addition, p in the figure is the significant difference value obtained when the t test is performed on different samples, which also indicates that there are significant differences in the data results between the control group and the experimental group.

[0055] Preferably, the method further comprises: measuring the particle size of the bacterial flora in the sludge on the 0th day, the 57th day, the 71st day and the 95th day using a laser diffraction particle size analyzer at a refractive index of 1.53.

[0056] In one embodiment of the present invention, the laser diffraction particle size analyzer used is Malvern Mastersizer 3000. Table 1 records the size of the anaerobic ammonium oxidation sludge particles at different test stages. As shown in Table 1, the table lists the relevant indicators of the sludge particle size of the control group and the test group at different test stages. Here, Dx (10), Dx (50) and Dx (90) respectively characterize the particle size corresponding to the cumulative particle size distribution number in the measured sample reaching 10%, 50% and 90%, respectively. It can be found from Table 1 that the particle size of the anaerobic ammonium oxidation sludge in the R2 test group is larger than that in the R1 control group, among which the difference is most obvious in Dx (90). For example, in the sample on the 95th day, the Dx (90) of the R2 group reached 420μm. Considering the discreteness of the particle size distribution, the formula used in the present invention is To calculate the particle size distribution in the sample, in the sample on the 95th day, the dispersion of R2 was calculated by the formula to be about 3.20, while the dispersion of R1 was 3.02. It can be seen that when the extreme particle size is excluded, the addition of magnetite leads to an increase in the average particle size of the bacterial community and makes the particle size of the bacterial community have a wider size distribution.

[0057]

[0058] Table 1 Anaerobic ammonium oxidation sludge particle size table

[0059] In one embodiment of the present invention, for the sludge particles obtained in this experiment, a scanning electron microscope combined with an energy dispersive X-ray spectrometer was used to calibrate the elemental composition of the bacterial flora in the sludge, wherein the iron element accounted for 12.64%.

[0060] On the 95th day of reactor operation, anaerobic ammonium oxidation sludge was taken out from the reactors of R1 and R2 respectively, and the microstructure of the bacterial community was characterized and the elemental composition and distribution were determined using a scanning electron microscope combined with an energy dispersive X-ray detector (SEM-EDS).

[0061] Figure 3 This is a schematic diagram of the microstructure of the bacterial flora in the control group and the experimental group in a method for enhancing the anaerobic ammonium oxidation performance using magnetite as the core of the present invention. Figure 3As shown, the anaerobic ammonium oxidation sludge in the R2 reactor is better granulated than that in R1, with a harder surface and a more regular shape. The present invention observes the sludge at the scale of 100 μm and 10 μm, and the distribution of iron, carbon and oxygen therein. It can be clearly observed that the distribution of iron in the R1 sludge is very uniform, mainly because the FeSO4 added to the influent matrix is ​​converted into divalent and trivalent iron ions in the water, and evenly participates in the reaction process of anaerobic ammonium oxidation.

[0062] It should be noted that in the present invention, magnetite nuclei with a size of 10-20 μm can be clearly observed inside the R2 sludge particles, and the elemental analysis results show that the proportion of iron can reach 12.64%. Through the aggregation of micron-sized magnetite nuclei, the anaerobic ammonia-oxidizing bacteria in the R2 sludge achieves bacterial aggregation, thereby showing better granulation characteristics.

[0063] In another embodiment of the present invention, during the R1 and R2 experiments, sludge can be taken out from the reactor every 10 to 15 days, and the extracellular polymers (EPS) of the sludge can be extracted by heat extraction. During the experiment, the number of biological replicates for each sample group was set to 3. The extracted extracellular polymers were used to determine the protein (PN) content using a BCA kit, and the polysaccharide (PS) content was determined using an anthrone-sulfuric acid method.

[0064] Figure 4 Schematic diagram of the process of EPS secretion by the microflora of the control group and the experimental group in a method of enhancing anaerobic ammonia oxidation performance using magnetite as a core of the present invention. Figure 4 As shown in the figure, the content of extracellular protein in the R2 group gradually increased from 0 to 71 days, and reached a peak of 355.6±35.1 mg / g TPN (Total Protein) on the 71st day, and then slowly decreased, which was 24.5% higher than that of the R1 group. The protein concentration in the R1 group reached a peak around 85 days, and was relatively lower than that of R2. Similarly, the polysaccharide content in R2 reached a peak of 146.1±22.4 mg / g TPN (Total Protein) on the 71st day, which was 63.4% higher than that of the R1 group. From 85 to 95 days, the polysaccharide and protein contents of the experimental group and the control group decreased significantly, and the decrease in polysaccharide was more significant.

[0065] In addition, the protein-polysaccharide content ratio gradually increased during the experiment and reached a peak around the 85th day, and then gradually decreased. It should be noted that in the R1 group, this ratio showed obvious fluctuations, with a peak of about 25, while in the R2 group, the peak of this ratio was within 10. In addition, at most points during the operation of the reactor, the PN / PS of the control group was significantly higher than that of the control group, and it was 56% higher at 95 days.

[0066] The total extracellular polymer concentration in the sludge also reached a peak at 71 days and then slowly decreased. At 71 days, the total EPS concentration of the R2 group was about 500 mg / L, significantly higher than the 380 mg / L of the R1 group. It can be seen that the R2 group used micron-sized magnetite as the core to ensure the balanced, stable and sufficient production of extracellular polymers of the bacterial community.

[0067] In one embodiment of the present invention, metagenomics technology is also used to further explain why the anaerobic ammonium oxidation sludge is more active in the presence of magnetite. After the reactor was operated for 95 days, 0.5 g of anaerobic ammonium oxidation sludge was evenly taken from the R1 and R2 reactors respectively, and the The total DNA of the sludge samples was extracted using the SPIN Kit for Soil (MPBIO, USA). After the DNA passed the quality inspection, the long-chain DNA fragments were cut using the Covaris M220 automatic focused ultrasonic crusher, and the double-end library was constructed using the Illumina sequencer.

[0068] In the process of sequencing data processing, the original sequence obtained by sequencing can be first trimmed into a pure sequence, and the quality control is performed using Sickle software to retain the sequences with a quality score of more than 20% or a sequence length greater than or equal to 50bp, and then the high-quality bases are assembled into contigs (Contig) and contigs (Scaffold) of known order using IDBA-UD software. The bases are used for genome splicing using MataBAT (v0.32.5), wherein the metagenomic binning tool Check M (v.1.0.7) can be used to realize the analysis of the integrity and contamination rate of the spliced ​​bins, and the bins with an integrity of ≥70% and a contamination rate of ≤10% are retained. Phylosift (v1.0.1) is used to identify species, and Prodigal (v.2.6.3) is used to predict open reading frames (ORF, Open Reading Frame). In addition, Diamand software is used to perform more detailed and accurate functional annotations and species identification on protein files such as KEGG and ncbi-nr.

[0069] Among them, nitrogen functional genes were obtained by comparison with the Ncyc_100 database. During the acquisition process, the screening threshold of blastP can be set to 1e-5. Gene abundance was calculated using BBmap software to obtain genome coverage, such as the number of reads per kilobase length of a gene per million reads (RPKM, Reads Per Kilobase per Million mapped reads). Relative abundance was obtained by normalizing the sum of the RPKM of the entire sample.

[0070] The results showed that the metagenomic data of the two samples obtained a total of 37 bins after removing redundancy. Figure 5 This is a diagram showing the changes in the bacterial community structure and nitrogen cycle functional genes in the whole sample of the control group and the experimental group in a method for enhancing anaerobic ammonia oxidation performance using magnetite as the core of the present invention. Figure 5 As shown, (a) is the distribution of bacterial communities classified by phylum in R1 and R2 obtained after NCBI-NR species identification. (b) is the distribution of bacterial community structure classified by genus. From the figure, it can be seen that the relative abundance of Candidatus Brocadia and Candidatus Kuenenia, which belong to anammox bacteria, increased from 34.5% and 1.65% in R1 to 36.6% and 2.29%, respectively. The micron iron particle core fully enhanced the activity of anaerobic ammonia oxidizing bacteria.

[0071] (c) is a gene change diagram of nitrogen cycle function, and the genes in the comparison include hzo, hdh, hzsB, nirK and nirS. Among them, hzsB is responsible for producing hydrazine from ammonia and nitric oxide, hzo and hdh are responsible for oxidizing hydrazine to nitrogen, and nirK and nirS are responsible for reducing nitrite to nitric oxide. As can be seen from the figure, the proportion of hzsB in R2 is 14% higher than that in R1, while hzo and hdh are slightly increased, increasing by 3.9% and 5.5% respectively, and nirK and nirS are increased by 4.5% and 33.6% respectively compared with R1. It can be seen that the present invention effectively activates the enzymes required in the anaerobic ammonium oxidation reaction process and improves the activity of the anaerobic ammonium oxidation reaction.

[0072] The present invention adds micron-sized magnetite in the UASB reactor, and the bacterial community secretes a large amount of extracellular polymers. The extracellular polymers and iron cores increase the particle size of the bacterial community, and the anaerobic ammonia oxidation activity is increased by 39%. The present invention has a simple process, high feasibility, easy-to-buy materials, is non-toxic and harmless to the environment, and is easy to apply in sewage treatment projects.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for enhancing the anaerobic ammonium oxidation performance using magnetite as a core, characterized in that: The method comprises the following steps: Step 1, starting the upflow anaerobic sludge blanket reactor and monitoring the denitrification effect of anaerobic ammonium oxidizing bacteria; The starting upflow anaerobic sludge blanket reactor comprises inoculating the upflow anaerobic sludge with a VSS of 1000-1100 mg / L pre-tamed into the upflow anaerobic sludge blanket reactor, introducing ammonium nitrogen and nitrite nitrogen with a concentration of 50 mg / L, and purging a mixed gas with a volume ratio of 95% nitrogen and 5% carbon dioxide, the upflow anaerobic sludge blanket reactor is always at a temperature of 37±1°C, and a water bath is used to control the temperature of the reactor to be stable, and the pH value of the reactor is maintained between 7.5 and 8.0, and the entire reaction process is cultured under light-proof conditions; Step 2, when the anaerobic ammonium oxidation denitrification effect reaches a preset index, adding micron-sized magnetite to the upflow anaerobic sludge blanket reactor to achieve continued cultivation of the anaerobic ammonium oxidizing bacteria; measuring the content of ammonium nitrogen or nitrite nitrogen to determine whether the anaerobic ammonium oxidation denitrification effect reaches the preset index; The preset index is that the startup of the upflow anaerobic sludge blanket reactor reaches 14 days or the ammonia nitrogen removal rate in the upflow anaerobic sludge blanket reactor reaches 90%; When the start-up time of the reactor reaches 90 days, the concentrations of ammonium nitrogen and nitrite nitrogen in the wastewater are adjusted to 200 mg / L, and the hydraulic retention time is adjusted to 12 hours; The particle size of the magnetite is 10 to 20 μm; and The magnetite is dissolved in the wastewater with the concentration of ammonium nitrogen and nitrite nitrogen of 50 mg / L respectively at a content of 1 g / L, so that the total nitrogen removal rate is maintained at more than 95% after 40 days.

2. A method for enhancing anaerobic ammonium oxidation performance using magnetite as a core according to claim 1, characterized in that: The volume of the upflow anaerobic sludge blanket reactor is 5L.

3. A method for enhancing anaerobic ammonium oxidation performance using magnetite as a core according to claim 1, characterized in that: The method further comprises: A control group was adopted, in which ferrous sulfate having the same concentration as that of magnetite was added to replace the magnetite with micron-sized particles, thereby achieving the cultivation of the anaerobic ammonia-oxidizing bacteria.

4. A method for enhancing anaerobic ammonium oxidation performance using magnetite as a core according to claim 1, characterized in that: The method further comprises: After the culturing of the anaerobic ammonium-oxidizing bacteria is completed, the anaerobic ammonium-oxidizing sludge is placed in an anaerobic state for shaking, and the sludge is sampled every 1 to 2 hours, and the supernatant is filtered through a 0.45 μm filter membrane for three nitrogen determination.

5. The method for enhancing the anaerobic ammonium oxidation performance using magnetite as a core according to claim 1, characterized in that: The method further comprises: The particle size of the bacterial flora in the sludge on days 0, 57, 71 and 95 was measured using a laser diffraction particle size analyzer at a refractive index of 1.53.

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