Nitrifying bacterium consortia, preparation method thereof and application of nitrifying bacterium consortia in wastewater treatment

Abstract

The invention relates to the technical field of water pollution control and treatment, in particular to a nitrifying bacteria consortium, a preparation method thereof and application of the nitrifying bacteria consortium in wastewater treatment. The nitrobacteria consortia comprises nitrosomonas sp. And nitrobacter winogradsky, and a compact and spherical cenobium structure is formed; the nitrification rate of the continuous passage of the nitrifying bacterium consortium is stabilized between 200-300mg NH4 < + >-N / L / h, so that the long-term stability of the nitrifying bacterium community is ensured; meanwhile, ammonia nitrogen can still be efficiently degraded under the extreme environmental conditions of high salt, high alkalinity, high aniline content and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water pollution control and treatment, and particularly relates to a nitrifying bacterial consortium, a preparation method thereof and application thereof in wastewater treatment. BACKGROUND

[0002] Nitrifying bacteria (including ammonia-oxidizing bacteria AOB and nitrite-oxidizing bacteria NOB) play a core role in nitrogen cycle and biological denitrification of wastewater. AOB oxidizes ammonia nitrogen (NH4 + ) to nitrite (NO2 - ), and NOB further converts nitrite to nitrate (NO3 - ), and the two of them cooperatively complete the nitrification process. The development of efficient nitrifying bacteria is the key to improving the efficiency of wastewater treatment. However, the existing technology still has problems such as low efficiency of separation of nitrifying bacteria, difficulty in high-density pure culture of AOB, difficulty in construction of consortium, and easy disintegration of consortium.

[0003] Traditional separation methods are time-consuming and have low success rate: plate streaking method, gradient centrifugation method and the like rely on the difference in growth rate of microorganisms, but the generation time of AOB / NOB (8-60 hours) is long, and the competitive growth of heterotrophic bacteria easily leads to separation failure.

[0004] AOB is difficult to achieve high-density pure culture: AOB grows slowly, and if the accumulation concentration of nitrite produced during the growth process is high, it will have significant feedback inhibition and toxic effects on AOB cells, seriously restricting their metabolic activity, and even leading to cell death. This characteristic makes it difficult for AOB to achieve high-density pure culture and single bacteria production, because it cannot avoid self-inhibition in its own metabolic process, and it is difficult to achieve large-scale fermentation production.

[0005] Lack of consortium research: In order to obtain microbial preparations with complete nitrification function, the prior art generally uses the method of enriching and domesticating nitrifying bacteria community from natural environment. However, this method has inherent defects: the enrichment process relies on the microbial community structure in the natural environment, the dominant bacteria have randomness, resulting in significant differences in strain species, activity and proportion of different batches of products, poor quality uniformity and poor stability in subculture. In the process of subculture or actual application, due to the different growth rates of AOB and NOB, the community structure is prone to succession, resulting in disintegration of functional consortium, rapid decay of nitrification efficiency and unpredictability, which limits its application in practice. For example, in the paper "Application of Chlorella pyrenoidosa nitrifying microbial co-culture in water quality purification of shrimp culture", nitrifying bacteria (mixed culture of AOB and NOB) and microalgae are used for water quality purification. Although it involves mixed bacteria, the technical core is the cross-border cooperation of nitrifying bacteria and exogenous microorganisms (algae), and the mixed culture of AOB and NOB is still the traditional method of co-enrichment, which cannot fundamentally solve the core technical problem of unstable internal structure of nitrifying bacteria and easy disintegration. SUMMARY

[0006] Therefore, the present application provides a nitrifying bacteria consortium, a preparation method thereof and application thereof in wastewater treatment. The technical problem of poor subculture stability and easy disintegration of the nitrifying bacteria consortium, which leads to nitrification failure, is solved. The nitrifying bacteria consortium constructed can maintain a nitrification rate of 200-300 mg NH4 + -N / L / h for at least 10 subcultures, and the fermentation density can reach 3.5x10 9 CFU / mL. At the same time, it can still efficiently degrade ammonia nitrogen under extreme environmental conditions such as high salt, high alkalinity and high total phenol content, and has wide application scenarios.

[0007] The technical scheme of the present application is as follows: In a first aspect, the present application provides a nitrifying bacteria consortium, which comprises Nitrosomonas europaea and Nitrobacter winogradskyi, forming a spherical bacterial cluster structure of Nitrosomonas europaea wrapping Nitrobacter winogradskyi.

[0008] On the basis of the above technical scheme, preferably, the classification name of the Nitrosomonas europaea is Nitrosomonas europaea SZG-AOB-002, and the preservation number is CCTCC NO: M 20232716; and the classification name of the Nitrobacter winogradskyi is Nitrobacter winogradskyi SZG-NOB-001, and the preservation number is CCTCC NO: M2022808.

[0009] The electron microscope (SEM) scanning of the bacterial liquid structure of the nitrifying bacteria consortium can observe that the Nitrosomonas europaea cells tightly wrap the Nitrosospira winogradskyi to form a dense, spherical granule structure, and some free Nitrosospira winogradskyi can be seen on the periphery of the granule. This tight structure greatly enhances the physical stability of the consortium, making it not easy to be dispersed by hydraulic shear force, avoiding the disintegration of the consortium.

[0010] In a second aspect, a culture method of the nitrifying bacteria consortium is provided, preferably, the isolated ammonia-oxidizing bacteria and nitrite-oxidizing bacteria are mixed and fed for culture.

[0011] On the basis of the above technical solutions, preferably, the inoculation volume ratio of the ammonia-oxidizing bacteria and the nitrite-oxidizing bacteria is (1-2):(1-3); further preferably, the inoculation volume ratio of the ammonia-oxidizing bacteria and the nitrite-oxidizing bacteria is 1:3.

[0012] On the basis of the above technical solutions, preferably, the fed-batch culture is fed with a feed solution according to the ammonia nitrogen consumption, subcultured, and the pH is adjusted to 7.5-8.0 with an alkali solution; the feeding frequency is 2-14 times.

[0013] On the basis of the above technical solutions, preferably, the feed solution for feeding is ammonium sulfate, the alkali solution is Na2CO3, and the subculture is 10 times.

[0014] On the basis of the above technical solutions, further preferably, the seed solution combined according to the optimal ratio is taken out, inoculated into fresh shake flask medium at an inoculation amount of 10% (v / v), initially fed with 0.6 mL of 100 g / L (NH4)2SO4 feed solution, cultured at 30°C and 200 r / min. The ammonia nitrogen consumption in the shake flask is detected qualitatively at regular time every day, and when the ammonia nitrogen consumption is completed, 0.6 mL of the feed solution is added again, and the pH is adjusted to 7.5-8.0 with 100 g / L Na2CO3 alkali solution for feeding, and the feeding is 7 times.

[0015] By optimizing the inoculation ratio of the ammonia-oxidizing bacteria and the nitrite-oxidizing bacteria, the subculture frequency, and the like, a structurally stable nitrifying bacteria consortium is artificially constructed, the nitrification rate of the nitrifying bacteria consortium is stably maintained at 200-300 mg NH4 + -N / L / h after 10 times of continuous subculture, and the bacterial number in the shake flask fed-batch culture reaches 3.5×10 9 CFU / mL, which is much higher than the 2.0×10 8 CFU / mL level reported in related literatures.

[0016] In a third aspect, the nitrifying bacteria consortium is applied to degrading ammonia nitrogen in wastewater.

[0017] Preferably, the concentration of ammonia nitrogen in the wastewater is ≤140 mg / L.

[0018] Preferably, the alkalinity in the wastewater is ≤3000 mg / L; further preferably, the alkalinity in the wastewater is ≤1500 mg / L.

[0019] Preferably, the salinity in the wastewater is ≤30000 mg / L; further preferably, the salinity in the wastewater is ≤15000 mg / L.

[0020] Preferably, the aniline content in the wastewater is ≤10 mg / L; further preferably, the aniline content in the wastewater is ≤5 mg / L.

[0021] The nitrobacteria consortium of the present application has the following beneficial effects over the prior art: 1. The nitrobacteria consortium artificially constructed by the present application forms a compact, spherical granular structure, is not easy to disintegrate, can maintain a stable nitration rate of 200-300 mg NH4 + -N / L / h during stable subculture, and the fermentation density can reach 3.5 x 10 9 CFU / mL.

[0022] 2. According to the relay oxidation relationship of ammonia by AOB and NOB, the artificial synthesis of the consortium overcomes the inhibition of metabolic products on growth during separate culture of the two bacteria, realizes high-density co-culture of the two bacteria, and improves the production efficiency; through optimization of the ratio, subculture and feeding times, etc., the nitrobacteria consortium with the characteristics of rapid proliferation, stable structure, easy-to-control culture, strong adaptability, and resistance to impact of various harmful substances is obtained, and a stable micro-ecosystem is formed, which ensures that the optimal ratio of AOB and NOB is maintained during long-term subculture and continuous operation, effectively solves the core disadvantage of easy disintegration of naturally enriched bacterial flora, and significantly improves the long-term stability of the nitrobacteria flora.

[0023] 3. The AOB strain is purified by flow sorting, which improves the efficiency of traditional plate screening of nitrobacteria.

[0024] 4. The consistency and repeatability of the bacterial agent product are ensured: the present application adopts a standardized process of artificial directional screening and rational splicing, which avoids the randomness of the natural enrichment process. The artificial consortium prepared in different batches has high consistency and repeatability in strain composition, ratio and functional performance, which solves the problem of large fluctuation of product quality in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or the prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only aim to some embodiments of the present application, and all other embodiments obtained by those of ordinary skill in the art without any creative work on the basis of these drawings also belong to the protection scope of the present application.

[0026] Figure 1 A colony morphology chart of the Nitrobacter winogradskyi in the present application; Figure 2 A feeding growth curve chart of the nitrobacterial consortium in the present application; Figure 3 A nitration rate change chart of the nitrobacterial consortium continuous passage in the present application; Figure 4 A cell electron microscope chart of the nitrobacterial consortium in the present application; Figure 5 A nitration rate change chart of the nitrobacterial consortium continuous passage in the present application; Figure 6 A trend chart of ammonia nitrogen change in different alkalinity landfill leachate using the nitrobacterial consortium in Example 6 of the present application; Figure 7 A municipal wastewater ammonia nitrogen change chart of the nitrobacterial consortium under different aniline concentrations in Example 7 of the present application; Figure 8 A municipal wastewater ammonia nitrogen change chart of the nitrobacterial consortium under different salinity in Example 8 of the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative work on the basis of the present application also belong to the protection scope of the present application.

[0028] Example 1 Screening, isolation and identification of AOB strains.

[0029] A certain amount of sample (0.2-0.4g soil, 1mL activated sludge, and 4mL lake water) was added to a 250mL Erlenmeyer flask containing 50mL of nitrifying bacteria enrichment medium (Minimum Mineral Salt Medium, with ammonia nitrogen added as substrate) and cultured at 30℃ and 200r / min on a shaker. The formation of nitrite was qualitatively detected weekly using a nitrite colorimetric reagent to determine the enrichment status. After one week of culture, the sample was replenished once with sterile 100g / L (NH4)2SO4 solution, reaching the initial substrate concentration of the medium. After two weeks of culture, the sample was transferred to fresh medium with an inoculum of 20%. This process of culture-replenishment-transfer was repeated for 2-3 months, and the amount of nitrite in each enriched sample was quantitatively determined. The group with faster enrichment was selected to detect AOB abundance. After enrichment, a highly efficient enrichment solution that could tolerate 2000mg / L alkaline landfill leachate and 10mg / L aniline was obtained and named AA.

[0030] Sample pretreatment: The enrichment solution was sonicated at 120W for 3 min to disperse the cells. The sonicated enrichment solution was then diluted with sterile culture medium to a bacterial count of 1×10⁻⁶. 6 The sample was processed at a density of 1 / mL, filtered through a 300-mesh filter cloth, and dispensed into sterile 2mL centrifuge tubes.

[0031] Determination of the distribution area of ​​the reference strain: Using the sorting function of the flow cytometer, the main distribution area was determined based on the forward angle (FSC) and side angle (SSC) scattered light signals generated by the cells. Referring to the FSC and SSC data, different particle regions were selected for sorting. After loading the strain, the injection flow rate was adjusted to 1000 particles / s, and 10,000 particle data were collected. 180 μL of AOB liquid medium containing phenol red was pre-dispensed into each well of a 96-well microplate, and the flow cytometry-sorted samples were collected using the wells containing the medium.

[0032] Sorted culture: After sorting, the microplates were cultured statically at 28℃ in the dark for 21 days. Then, 30 μL of bacterial solution was taken from the wells that turned yellow and mixed with 10 μL of nitrite chromogenic reagent for qualitative testing. Wells that turned red were positive. A small amount of bacterial solution was taken with a sterile pipette tip and streaked on an LB plate. The positive wells without colony growth were selected and transferred to 2 mL deep-well plates and 500 mL shake flasks for expansion culture. The expanded bacterial solution was streaked again to verify the purity and identify the bacterial species.

[0033] Five 96-well plates were sorted using AA, and the overall positive rate was 75.8% after plate-by-plate testing. All positive wells were streaked for purity testing, and only AAP4-B7 showed no contamination. After 16S expansion, the bacteria were identified as *Nitrosomonas cerevisiae* (European Nitrosomonas). Nitrosomonas europaea ).

[0034] Example 2 Enrichment and isolation of NOB strains.

[0035] A certain amount of sample (0.2-0.4g soil, 1mL activated sludge, and 4mL lake water) was taken for enrichment. After centrifugation of the sediment, the supernatant was discarded, and the precipitate was added to the enrichment medium at 10% (w / v). Enrichment was carried out at 28-30℃ and 200rpm on a shaker. The changes in nitrite nitrogen (NO2-N) and nitrate nitrogen (NO3-N) content in the medium were monitored daily. Once the nitrite nitrogen in the medium dropped to 0 mg / L, nitrite nitrogen was added. When the accumulated nitrate nitrogen exceeded 1000 mg / L, it was inoculated again into a new medium at a ratio of 10% (v / v), while increasing the nitrite nitrogen content. After two months of acclimatization using this method, the microbial NO2-N degradation efficiency in the enriched solution increased to 100 mg / L·h, resulting in an enriched solution with a nitrifying bacteria abundance of 30%. This enriched solution was purified using a gradient dilution method and a solid dilution plating combined with streak plating.

[0036] Dilution coating method and streak plating purification: Dilute the above enriched solution with pure water to a concentration of 10. -1 ~10 -7 Seven cell / mL gradients were calculated, with 100 μl of each gradient plated onto solid purification medium. Each gradient was replicated in triplicate. The plates were incubated at 30°C for two weeks. Different colonies that grew on the plates were then streaked for purification. After enrichment, 8 enriched solutions with nitrite degradation ability were obtained from 14 samples. The nitrite oxidation rate was measured, and the enriched solution S2 with the highest rate was selected as the target for subsequent NOB experiments. After multiple rounds of enrichment, transfer, isolation, and purification, strain S2 grew on solid culture medium for 14-21 days, exhibiting a transparent pinhead morphology, with colonies as shown in the image. Figure 1 As shown. Single colonies were picked from the plate and identified by 16S rRNA, confirming they were *Nitrosobacterium velutipes* (…). Nitrobacter winogradskyi ).

[0037] Example 3 Optimization of the inoculation ratio for artificial synthesis of nitrifying bacteria aggregates.

[0038] The AOB strain AA and NOB strain S2 isolated in Examples 1 and 2 were subjected to fed-batch culture. The total inoculum was 10% (v / v), and AOB and NOB bacterial cultures were inoculated at inoculum ratios of 2:1, 1:1, 1:2, and 1:3, respectively. At the time of inoculation, AOB was cultured until the nitrification rate was approximately 100 mg NH4. + -N / L / h, NOB cultured to a rate of approximately 150 mg NO2 -N / L / h, 0.6 mL ammonium sulfate was added each time, and samples were taken daily for qualitative analysis of ammonia nitrogen consumption in the shake flasks. When ammonia nitrogen was depleted, another 0.6 mL of feed solution was added, and the pH was adjusted to 7.5-8.0 with 100 g / L Na₂CO₃ alkali solution. After 120 h of culture, the nitrification rate of each group was measured. The group with the highest rate and optimal ratio was selected for continuous subculturing, and the change in nitrification rate after the culture was completed was recorded. Nitrite, as an intermediate product of nitrifying bacteria metabolism, has an inhibitory effect on the growth of nitrifying bacteria. Under culture conditions of pH 7.8, Nitrosomonas europaea Growth ratio Nitrobacter winogradskyi Rapid growth can lead to the accumulation of nitrite in the culture medium. Studies have shown that high concentrations of nitrite can reduce... Nitrosomonas europaea AMO enzyme activity thus affects ammonia oxidation activity, and ammonia oxidation activity is reduced more at alkaline pH (7-8) than at acidic pH (5.5-6.5).

[0039] The nitrification rate data for different AOB:NOB inoculum ratios are shown in Table 1: Table 1

[0040] The growth rates of AOB and NOB cultured individually were not significantly different. When cultured in different proportions, the growth rate increased with the increase of the NOB inoculum ratio at the end of the culture. However, as the NOB inoculum ratio continued to increase, the nitrite nitrogen generated by AOB was insufficient for NOB growth, and the NOB growth rate decreased due to insufficient substrate. Therefore, an inoculum ratio of 1:3 was selected for subsequent experiments, denoted as composite AS2.

[0041] Example 4 Growth curves of artificially synthesized nitrifying bacteria aggregates.

[0042] The AS2 seed culture was removed from a 4℃ freezer and inoculated into fresh shake flask culture medium at a 10% inoculum rate. An initial feed of 0.6 mL of 100 g / L (NH4)2SO4 was added, and the culture was incubated at 30℃ and 200 rpm. Ammonia nitrogen consumption was qualitatively measured daily. When ammonia nitrogen was depleted, another 0.6 mL of feed was added, and the pH was adjusted to 7.5-8.0 with 100 g / L Na2CO3 alkali supplementation. Samples were taken at feed times 0, 2, 3, 5, 6, 7, 10, 11, 12, and 13 times after ammonia nitrogen depletion to measure nitrification rate and bacterial count, and growth curves of nitrifying bacteria were plotted. Figure 2 As shown.

[0043] pass Figure 3It was found that when the number of feeding cycles was ≤3, the nitrification rate of the nitrifying bacteria shake flask culture had a good correlation with the number of feeding cycles, and the nitrification rate increased significantly with the increase of feeding cycles. As the fed-batch culture progressed, the substrate consumption rate of the nitrifying bacteria increased rapidly. Inevitably, overnight cultures experienced problems with untimely feeding or alkali replenishment, such as the 4th, 8th, and 9th cycles. This resulted in a slight decrease in the nitrification rate after overnight culture compared to before overnight culture, but the rate resumed its upward trend after normal feeding was resumed during the day. A total of 14 feeding cycles were conducted during the entire culture period. The nitrification rate reached its highest value after 7 feeding cycles, and fluctuated after the 8th-14th feeding cycles. Simultaneously, the bacterial count of nitrifying bacteria showed a good correlation with the nitrification rate, reaching a maximum of 3.5 × 10⁻⁶ after 7 feeding cycles. 9 CFU / mL.

[0044] Example 5 Stability of artificially synthesized nitrifying bacterial aggregates through passage.

[0045] AOB / NOB was selected and inoculated at a ratio of 1:3. The synthesized AS2 polymer seed culture was continuously passaged for 10 generations, and the nitrification rate was continuously monitored. The results are as follows: Figure 3 As shown, the nitrification rate of the polymer is stable at 200-300 mg NH4. + The ratio of AOB to NOB is between -N / L / h, reflecting the long-term stability of the aggregated nitrifying bacteria community. This ensures that the optimal ratio of AOB to NOB is maintained during long-term subculturing and continuous operation, effectively solving the core drawback of the easy disintegration of naturally enriched bacteria communities.

[0046] The aggregates obtained from the above successive generations were scanned using a electron microscope (SEM), and the results are as follows: Figure 4 As shown, *Nitrosomonas cerevisiae* (European nitrosomonas) can be observed. Nitrosomonas europaea The cells tightly encapsulate *Nitrobacterium vesiculosus* ( Nitrobacter winogradskyi This process forms a dense, spherical bacterial aggregate structure, with some free *Nitrobacterium velutipes* visible on the periphery of the aggregate. This compact structure greatly enhances the physical stability of the aggregate, making it less susceptible to being dispersed by hydraulic shear forces. This effectively solves the technical problem of "easily disintegrating aggregates" and ensures stable ammonia nitrogen degradation function during long-term use, demonstrating excellent application prospects.

[0047] The above results demonstrate that the artificial aggregates constructed through the screening and optimized combination of specific strains in this invention successfully form a structurally stable, mutually beneficial symbiotic micro-ecosystem. This structure ensures that the nitrite produced by AOB can be efficiently and rapidly consumed by its neighboring NOB.

[0048] Comparative Example 1 AOB / NOB was selected and inoculated at a ratio of 1:5. The synthesized seed culture was continuously subcultured, and the nitrification rate was continuously monitored. The results are as follows: Figure 5 As shown, the rate of the polymer within 7 generations is 70~210 mg NH4. + Between -N / L / h, it shows a continuous downward trend, and the rate and stability are far lower than the 1:3 inoculation ratio rate.

[0049] Example 6 Application examples of nitrifying bacteria aggregates in landfill leachate with different alkalinities.

[0050] A real leachate sample from a landfill, after pretreatment to remove suspended solids, had an ammonia nitrogen concentration of approximately 140 mg / L. Different alkalinity levels were achieved through aeration and the addition of NaHCO3 or dilute HCl solution. Experiments were conducted using a series of sequencing batch reactors (SBRs) with an effective volume of 1 L. The biopolymers were cultured to a rate of 250 mg / L NH4+. + -N / L / h, 1% dosage, with a control group not given bacteria.

[0051] like Figure 6 As can be seen, the polymer of this invention exhibits significant ammonia nitrogen removal efficiency in landfill leachate with alkalinity ranging from 900 to 3000 mg / L, with the optimal removal efficiency at 900 mg / L, achieving an ammonia nitrogen removal rate exceeding 82% after 188 hours. Increasing the alkalinity to 1500 mg / L slightly enhances the inhibitory effect compared to 900 mg / L, but extends the total degradation time by 29 hours (from 7 days to 8 days). At an alkalinity of 2000 mg / L, nitrifying bacteria degrade ammonia nitrogen slowly, degrading only about 12 mg / L per 24 hours. Compared to the natural bacterial community in landfill leachate (the control group showed no effect), it demonstrates extremely strong environmental adaptability across a wide alkalinity range, especially effectively degrading ammonia nitrogen even at high alkalinity conditions below 2000 mg / L, thus solving the alkalinity tolerance problem of traditional nitrifying bacteria.

[0052] The polymer of this invention operates stably in leachate with different alkalinities and exhibits no activity decay. It can be applied to nitrification treatment processes of landfill leachate with different alkalinities and has significant industrial application value.

[0053] Example 7 Application examples of nitrifying bacterial aggregates degrading ammonia nitrogen in municipal wastewater at different aniline concentrations.

[0054] Municipal wastewater was taken from the inlet of a city's sewage treatment plant, with an ammonia nitrogen concentration of approximately 48 mg / L, COD of 150-200 mg / L, pH of 7.5-7.8, and an aniline concentration of 0. The following groups were established by adding analytically pure aniline: 0 mg / L group (aniline-free control group), 0.5 mg / L group, 1 mg / L group, 3 mg / L group, 5 mg / L group, 10 mg / L group, and a control group without added aerobic polymers. Bacteria were added to each experimental group (except the CK group) at a uniform rate of 250 mg / L NH4+. + -N / L / h, the inoculum amount is 1% (V / V) of the effective volume of the reactor; the CK group is inoculated with an equal amount of municipal wastewater without the addition of the strain.

[0055] Experimental results are as follows Figure 7 As shown, the polymeric strain of this invention exhibits significant ammonia nitrogen removal efficiency in municipal wastewater with aniline concentrations of 0-10 mg / L, with the optimal removal efficiency at 0-1 mg / L, achieving 100% ammonia nitrogen removal rate after 64 hours. At aniline concentrations of 3-5 mg / L, the ammonia nitrogen degradation effect is delayed by 1 day compared to the control group. 10 mg / L aniline partially inhibits nitrifying bacteria, but as the bacteria gradually adapt, degradation is completed by 135 hours. In contrast, the natural bacterial community in the control group of municipal wastewater requires 159 hours to degrade ammonia nitrogen, while the polymeric strain of this invention only requires 64 hours, demonstrating a unique ability to maintain nitrification activity in aniline-containing municipal wastewater. This strain can be applied to the nitrification treatment process of municipal wastewater containing aniline pollutants.

[0056] Example 8 Application examples of nitrifying bacterial aggregates in degrading ammonia nitrogen in municipal wastewater at different salinities.

[0057] Municipal wastewater was taken from the inlet of a city's sewage treatment plant, with an ammonia nitrogen concentration of 48 mg / L, COD of 150-200 mg / L, pH of 7.5-7.8, and salinity of 200-300 mg / L. The following salinity groups were established by adding analytical grade sodium chloride: 0 mg / L, 5000 mg / L, 10000 mg / L, 15000 mg / L, 20000 mg / L, 25000 mg / L, 30000 mg / L, and a control group without added agglomerates. Agglomerates were added to all experimental groups (except the control group), with a uniform bacterial growth rate of 250 mg / L NH4+. + -N / L / h, the inoculum amount is 1% (V / V) of the effective volume of the reactor; the CK group is inoculated with an equal amount of municipal wastewater without added polymers.

[0058] Experimental results are as follows Figure 8As shown, ammonia nitrogen can be effectively degraded in the salinity range of 0~30000 mg / L. Ammonia nitrogen can be completely removed in the range of 0~15000 mg / L (removal rate 100%), while some activity is still maintained in the range of 25000~30000 mg / L.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A nitrifying bacteria aggregate, characterized in that: The nitrifying bacteria aggregate includes *Nitrosomonas cerevisiae* and *Nitrobacterium vesiculosus*, forming a spherical bacterial clump structure in which *Nitrosomonas cerevisiae* encapsulates *Nitrobacterium vesiculosus*.

2. The method for preparing nitrifying bacterial aggregates as described in claim 1, characterized in that: The isolated ammonia-oxidizing bacteria and nitrite-oxidizing bacteria were mixed and fed a culture.

3. The method for preparing nitrifying bacterial aggregates as described in claim 2, characterized in that: The volume ratio of the inoculum of ammonia-oxidizing bacteria to nitrite-oxidizing bacteria is (1~2):(1~3).

4. The method for preparing nitrifying bacterial aggregates as described in claim 2, characterized in that: The fed culture is carried out by adding feed solution according to the ammonia nitrogen consumption, and the pH is adjusted to 7.5-8.0 with alkaline solution; the feeding is carried out 2-14 times.

5. The application of the nitrifying bacteria aggregate as described in claim 1 in the degradation of ammonia nitrogen in wastewater.

6. The application as described in claim 5, characterized in that: The concentration of ammonia nitrogen in the wastewater is ≤140mg / L.

7. The application as described in claim 5, characterized in that: The alkalinity of the wastewater is ≤3000mg / L.

8. The application as described in claim 5, characterized in that: The salinity of the wastewater is ≤30000mg / L.

9. The application as described in claim 5, characterized in that: The aniline content in the wastewater is ≤10mg / L.

10. A bacterial agent for wastewater treatment, characterized in that: It includes the nitrifying bacteria aggregate as described in claim 1.

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