Iron-rich inclusion anaerobic ammonia oxidation particles, and methods of making and using the same

Abstract

The application discloses an iron-rich inclusion anaerobic ammonia oxidation particle as well as a preparation method and application thereof, and belongs to the field of nitrogen-containing wastewater treatment. The preparation method of the iron-rich inclusion anaerobic ammonia oxidation particle comprises the following steps: inoculating sludge in an anaerobic ammonia oxidation particle sludge reactor, introducing wastewater, adding excess zero-valent iron during the operation of the reactor, and obtaining the iron-rich inclusion anaerobic ammonia oxidation particle after the operation is completed. According to the application, the excess zero-valent iron is continuously added to the anaerobic ammonia oxidation particle sludge, a uniform iron-rich inclusion protective barrier is formed on the surface of the anaerobic ammonia oxidation particle, and the application performance of the anaerobic ammonia oxidation particle in treating high-load and toxic wastewater is strengthened.

Description

Technical Field

[0001] This invention relates to the field of nitrogen-containing wastewater treatment, specifically to an iron-rich anaerobic ammonia oxidation particle, its preparation method, and its application. Background Technology

[0002] Anaerobic ammonia oxidation (AAO) is a novel biological nitrogen removal method that directly oxidizes ammonia nitrogen into nitrogen gas using nitrite as an electron acceptor. Compared to traditional nitrification-denitrification processes, AAO offers significant advantages: it eliminates the need for additional aeration and external organic carbon sources, greatly reduces sludge production, and has enormous potential for energy conservation, greenhouse gas emission reduction, and lower operating costs. However, in practical applications, AAO faces numerous challenges. Nitrogenous wastewater typically exhibits large volumes and complex compositions. High influent loads and toxic substances in the wastewater can severely inhibit and toxicize the AAO process, thereby affecting the stable operation of the AAO granular sludge reactor.

[0003] Zero-valent iron (ZVFe) shows great promise for promoting anammox due to its high reducing activity and stable Fe(II) release characteristics. Iron plays a crucial role in the metabolism of anammox bacteria, which are rich in iron-containing substances such as heme c, iron-sulfur clusters, and iron-nickel proteins, as well as other iron-containing coenzyme factors, all of which participate in nitrogen metabolism-related reactions. Furthermore, studies have shown that iron significantly affects the activity of three key enzymes in anammox. Therefore, the addition of small amounts of ZVFe to promote anammox has attracted widespread attention from researchers. However, adding small amounts of ZVFe can only improve the performance of anammox systems to a certain extent, and it is still difficult to completely overcome the limitations of anammox granular sludge when facing high loads and toxic substances. Summary of the Invention

[0004] The purpose of this invention is to provide an iron-rich encapsulated anammox granule, its preparation method, and its application. This invention continuously adds excess zero-valent iron to the anammox granule sludge, forming a uniform iron-rich protective barrier on the surface of the anammox granule, thereby enhancing the performance of the anammox granule in treating high-load and toxic wastewater.

[0005] This invention first provides a method for preparing iron-rich inclusion anaerobic ammonia oxidation particles, comprising the following steps:

[0006] Sludge was inoculated into an anaerobic ammonia oxidation granular sludge reactor, wastewater was introduced, excess zero-valent iron was added during reactor operation, and the iron-rich inclusion anaerobic ammonia oxidation granules were obtained after the operation was completed.

[0007] In the above preparation method, the sludge is anaerobic ammonia oxidation granular sludge;

[0008] The inoculation concentration of the sludge is 20-40 g / L;

[0009] The concentrations of ammonia nitrogen and nitrite nitrogen in the wastewater are both 100-500 mg / L; specifically, they can be 250 mg / L.

[0010] The influent nitrogen load of the wastewater is 0.5-10 kg N / m³. 3 / d.

[0011] Specifically, the influent nitrogen load of the wastewater is 0.5-5 kg-N / m³ in the initial stage. 3 / d, later stage is 5-10 kg-N / m 3 / d;

[0012] The early stage refers to days 1-50 of the load experiment, and the later stage refers to days 51-86 of the load experiment.

[0013] In the above preparation method, the final amount of zero-valent iron added is 1.5-10 g / g-VSS; specifically, it can be 1.5-6 g / g-VSS; more specifically, it can be 2.03 g / g-VSS.

[0014] The final amount of zero-valent iron added refers to the ratio of the concentration of zero-valent iron added (g / L) to the concentration of inoculated sludge (g-VSS / L).

[0015] The concentration of zero-valent iron added refers to the total mass of zero-valent iron added throughout the process divided by the total volume of the reactor.

[0016] The anaerobic ammonia oxidation granular sludge reactor is an upflow anaerobic sludge bed reactor.

[0017] In the above preparation method, the concentration of excess zero-valent iron added during reactor operation is 1-10 g / L, and the amount of zero-valent iron added is dynamically adjusted according to the denitrification effect during reactor operation to avoid reactor collapse due to excessive addition of zero-valent iron, until a uniform iron-rich inclusion is formed on the surface of the anaerobic ammonia oxidation particles.

[0018] The present invention also provides iron-rich inclusion anaerobic ammonia oxidation particles prepared by the above preparation method.

[0019] According to the scanning electron microscopy energy dispersive spectroscopy analysis, the iron content on the surface of the aforementioned iron-rich inclusion anaerobic ammonium oxidation particles is above 30%; specifically, it can be 30%-60%.

[0020] Finally, the present invention provides the application of the above-mentioned iron-rich inclusion anaerobic ammonia oxidation particles in any of the following:

[0021] (1) Denitrification treatment of high-load nitrogen-containing wastewater;

[0022] (2) Denitrification treatment of nitrogen-containing wastewater containing heavy metals and / or antibiotics.

[0023] In the above applications, the denitrification load for the high-load nitrogen-containing wastewater is 30-60 kg-N·m. -3 ·d -1 Specifically, it can be 40 kg-N·m -3 ·d -1 .

[0024] In the above applications, the concentration of heavy metals in the nitrogen-containing wastewater containing heavy metals and / or antibiotics is 50-1000 mg / L, and the concentration of antibiotics is 1-100 mg / L.

[0025] Specifically, the concentration of the heavy metal is 500 mg / L, and the concentration of the antibiotic is 10 mg / L;

[0026] Specifically, the heavy metal may be at least one of nickel, manganese, iron, chromium, cadmium, copper, zinc, lead, mercury, silver, and arsenic; the antibiotic may be at least one of tetracycline, oxytetracycline, sulfamethoxazole, erythromycin, spiramycin, clarithromycin, norfloxacin, and ciprofloxacin.

[0027] In the above applications, the concentrations of ammonia nitrogen and nitrite nitrogen in the nitrogen-containing wastewater containing heavy metals and / or antibiotics are both 400-700 mg / L; specifically, they can be 500-600 mg / L.

[0028] In the above applications, the inoculum concentration of the iron-rich inclusion anaerobic ammonia oxidation particles in the denitrification treatment of nitrogen-containing wastewater is 1-40 g / L.

[0029] This invention, by controlling the amount and frequency of zero-valent iron (ZVFe) addition, forms iron-rich inclusion anaerobic ammonia oxidation (AAMO) granular sludge reactors. Under the collimating effect of extracellular polymeric substances (EPS) secreted by anaerobic ammonia oxidizing bacteria, iron ions and iron minerals generated from the hydrolysis of ZVFe form loose, porous iron-EPS inclusions on the particle surface. The hydrophobic proteins in EPS further promote the aggregation of these inclusions, ultimately forming stable and uniformly coated iron-rich inclusion AAMO granules. These iron-rich inclusions significantly improve the activity, mechanical strength, settling properties, and metabolic potential of the AAMO granules, greatly enhancing their resistance to high loads and toxic substances.

[0030] The present invention has the following beneficial effects:

[0031] (1) The present invention significantly enhances the activity of anammox by forming iron-rich inclusions on the surface of anammox particles; the inclusions not only strengthen the mechanical strength and sedimentation performance of the particles, but also improve the performance related to nitrogen metabolism and iron metabolism; this unique structure provides strong metabolic potential for anammox microorganisms, thereby enhancing the overall performance of anammox particles.

[0032] (2) The iron-rich inclusion anaerobic ammonia oxidation particles obtained by the present invention significantly enhance their adaptability to adverse environmental pressures such as heavy metals, antibiotics and high loads; the iron-rich inclusion endows the anaerobic ammonia oxidation particles with excellent resistance, enabling them to maintain basic performance when facing various environmental stresses and ensuring stable operation under adverse conditions; this unique iron-rich inclusion structure plays a role in protecting and strengthening the anaerobic ammonia oxidation particles, improving their environmental adaptability and application potential; through the method of the present invention, the stress resistance of anaerobic ammonia oxidation particles has been significantly improved, laying a solid foundation for their application in complex and ever-changing actual environments; this technology also provides a novel and effective strategy for enhancing the environmental adaptability of anaerobic ammonia oxidation particles. Attached Figure Description

[0033] Figure 1 Electron microscopy images and energy dispersive spectroscopy analysis of anaerobic ammonia oxidation particles without iron-rich inclusions and anaerobic ammonia oxidation particles with iron-rich inclusions, showing the iron distribution and iron content on their surfaces. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments. The embodiments given are only for illustrating the present invention and are not intended to limit the scope of the present invention.

[0035] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.

[0036] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0037] In Example 1 below, the inoculated sludge was anaerobic ammonia oxidizing bacteria granular sludge, purchased from Company A and Company B.

[0038] Example 1

[0039] Two anaerobic ammonia oxidation granular sludge reactors (UASB, upflow anaerobic sludge bed reactors) were used. The sludge inoculum concentration was 34.5 g / L, and the influent ammonia nitrogen and nitrite nitrogen concentrations were both 250 mg / L. The influent nitrogen loading was 3.60 kg-N / m³ in the initial stage (days 1-50). 3 / d, with a later stage (days 51-86) of 7.20 kg-N / m 3The reactor operated for a total of 86 days. A small, continuous excess of zero-valent iron (purchased from Aladdin, catalog number I434865-25g) was added to one reactor. From days 1 to 20, the concentration of zero-valent iron was 1 g / L, added every 2 days (the first addition was on day 1, and the last addition was on day 19). From days 21 to 50, the concentration of zero-valent iron was 2 g / L, added every 3 days (the first addition was on day 21, and the last addition was on day 48). From days 51 to 66, the concentration of zero-valent iron was 4 g / L, added every 4 days (the first addition was on day 51, and the last addition was on day 63). From days 67 to 86, the concentration of zero-valent iron was 6 g / L, added every 5 days (the first addition was on day 67, and the last addition was on day 82). The final addition amount of zero-valent iron reached 2.03 g / g-VSS. The other reactor, following conventional methods, added only a small amount of zero-valent iron (ZFe). From days 1 to 20, the ZFe concentration was 1 g / L, added every 10 days (i.e., added on days 1 and 10). From days 21 to 50, the ZFe concentration was 2 g / L, added every 30 days (i.e., added on day 21). From days 51 to 66, the ZFe concentration was 4 g / L, added every 16 days (i.e., added on day 51), with a final ZFe addition of 0.23 g / g-VSS. During the ZFe addition process, the operating conditions of both reactors were identical. The operating temperature of both reactors was 30°C.

[0040] The wastewater used in this example was prepared in the laboratory, and its specific components and concentrations are as follows: (NH4)2SO4 250 mg / L, NaNO2 250 mg / L, EDTA 0.005 g / L, KH2PO4 0.054 g / L, KHCO3 1.25 g / L, FeSO4·7H2O 0.009 g / L, trace element I solution 1 mL / L, and trace element II solution 2 mL / L. The composition and concentration of the trace element I solution are as follows: CoCl2·6H2O 0.24 g / L, CuSO4·5H2O 0.25 g / L, H3BO3 0.014 g / L, MnCl2·4H2O 0.99 g / L, Na2MoO4·2H2O 0.22 g / L, NiCl·6H2O 0.19 g / L, ZnSO4·7H2O 0.43 g / L; the composition and concentration of the trace element II solution are as follows: CaCl2·2H2O 0.927 g / L, KCl 0.7 g / L, MgSO4·7H2O 1.027 g / L, NaCl 0.5 g / L.

[0041] After operation, granular sludge was removed from the reactor and subjected to electron microscopy. The results are shown below. Figure 1.Depend on Figure 1 It can be seen that in a reactor with an excess of zero-valent iron, a uniformly distributed layer of iron-rich inclusions forms on the surface of the anaerobic ammonia oxidation particles (see...). Figure 1 (b) According to energy dispersive spectroscopy analysis, the iron content on the particle surface is as high as 30.32% (see [reference]). Figure 1 (b-1 in the text). In contrast, no formation of iron-rich inclusion anaerobic ammonia oxidation particles was observed in the reactor with a small amount of zero-valent iron added. Figure 1 (a) According to energy dispersive spectroscopy analysis, the proportion of iron on the particle surface is only 0.42% (see a). Figure 1 (a-1 in the text).

[0042] Example 2: Application of iron-rich inclusion anaerobic ammonia oxidation particles in the treatment of high-load nitrogen-containing wastewater

[0043] Simulated wastewater (the composition of which was the same as that used in Example 1, except for the concentrations of ammonia nitrogen and nitrite nitrogen) was introduced into the reactor after the operation of Example 1. The influent ammonia nitrogen and nitrite nitrogen concentrations were 250 mg / L in the early stage (days 1-7), 300 mg / L in the middle stage (days 8-18), and 350 mg / L in the late stage (days 19-30). The hydraulic retention time was 0.83 hours in days 1-4, 0.67 hours in days 5-11, 0.56 hours in days 12-14, and 0.042 hours in days 15-30. The influent load was also adjusted from the initial 14.4 kg-N·m -3 ·d -1 Gradually reaching 40 kg-N·m -3 ·d -1 In reactors where iron-rich inclusions did not form, the denitrification load only gradually increased with the influent load during the first 8 days, reaching a maximum of 13.1 kg-N·m³. -3 ·d -1 However, starting from day 9, the nitrogen removal load dropped sharply, falling to 0.8 kg-N·m³ by day 20. -3 ·d -1 By day 30, the reactor had almost completely lost its denitrification capacity. However, the iron-rich inclusion anaerobic ammonia oxidation granular sludge reactor exhibited excellent denitrification performance, maintaining a denitrification efficiency above 90% under high load conditions, with a denitrification load reaching 21.5 kg-N·m³ by day 8. -3 ·d -1 Subsequently, the denitrification load continued to increase steadily with the influent load, reaching 37.4 kg-N·m³ on day 20. -3 ·d -1 And it has remained at this high level steadily throughout the subsequent process.

[0044] Example 3: Application of iron-rich inclusion anaerobic ammonia oxidation particles in the treatment of arsenic-containing wastewater

[0045] After the reactor operation in Example 1 was completed, 20 mL of anaerobic ammonia oxidation granular sludge from each of the two reactors was taken into 550 mL serum bottles, and 500 mL of nitrogenous wastewater was added to each bottle. The sludge concentration in the serum bottles was 1.2 g / L. The concentrations of ammonia nitrogen and nitrite nitrogen in the nitrogenous wastewater were 500 mg / L and 600 mg / L, respectively. The concentration of arsenic pentoxide in the pentavalent arsenic wastewater was 500 mg / L, and the concentration of arsenic trioxide in the trivalent arsenic wastewater was 300 mg / L. The remaining components were the same as those used in Example 1. The serum bottles were placed on a constant-temperature shaker at 180 rpm and the temperature was controlled at 33±1℃. When the NH4+ in the serum bottles... + -N and NO2 - -N concentration decreased to 50 mg·L -1 When the following occurs, ammonium sulfate and sodium nitrite are replenished to make NH4+. + -N and NO2 - -N to the initial concentration, and begin the next experimental cycle. This batch of experiments lasted 26 days and completed 8 cycles. For anaerobic ammonia oxidation particles that did not form iron-rich inclusions, a significant inhibitory effect was observed in the first cycle, with a denitrification efficiency of only 10.9%. With prolonged exposure time, the denitrification efficiency continued to decline, reaching almost zero by the 6th cycle (day 15), and showed no recovery in subsequent cycles, ultimately losing almost complete denitrification capacity. In contrast, iron-rich inclusion anaerobic ammonia oxidation particles showed significant resistance in the treatment of arsenic-containing wastewater. In the first cycle, these particles exhibited a high denitrification efficiency of 69.0%. With increasing cycle count, the adaptability of these particles to arsenic gradually increased, reaching a denitrification efficiency of 81.3% by the 4th cycle (day 7), and maintaining this high level throughout the subsequent cycles until the end of the 8th cycle (day 26).

[0046] Each experiment was repeated three times, and the results were averaged.

[0047] Example 4: Application of iron-rich inclusion anaerobic ammonia oxidation particles in the treatment of antibiotic-containing wastewater

[0048] After the reactor operation in Example 1 was completed, 20 mL of anaerobic ammonia oxidation granular sludge from each of the two reactors was taken into 550 mL serum bottles, and 500 mL of nitrogen-containing wastewater was added to each bottle. The sludge concentration in the serum bottles was 1.2 g / L. The composition and concentration of the nitrogen-containing wastewater were as follows: ammonia nitrogen and nitrite nitrogen concentrations were 500 mg / L and 600 mg / L, respectively; tetracycline or sulfamethoxazole concentration was 10 mg / L; and the remaining components were the same as those used in Example 1. The serum bottles were placed on a constant-temperature shaker at 180 rpm and the temperature was controlled at 33±1℃. When the NH4+ in the serum bottles... + -N and NO2 - -N concentration decreased to 50 mg·L -1 When the following occurs, ammonium sulfate and sodium nitrite are replenished to make NH4+. + -N and NO2 - -N to the initial concentration, and begin the next experimental cycle. This batch of experiments lasted 26 days and completed 8 cycles. For anaerobic ammonium oxidation particles that did not form iron-rich inclusions, their denitrification efficiency was only 14.7% in the first cycle. As the stress time increased, their denitrification efficiency gradually decreased, reaching almost 0 in the 7th cycle (day 19), and did not recover in subsequent cycles, eventually almost completely losing its denitrification function. In contrast, iron-rich inclusion anaerobic ammonium oxidation particles showed significant antibiotic resistance. Their denitrification efficiency reached 77.4% in the first cycle. After a short adaptation period, the denitrification efficiency of iron-rich inclusion anaerobic ammonium oxidation particles reached 92.4% in the 3rd cycle (day 4) and remained stable in subsequent cycles, consistently maintaining a high level of denitrification efficiency.

[0049] Each experiment was repeated three times, and the results were averaged.

Claims

1. A method for preparing iron-rich inclusion anaerobic ammonia oxidation particles, comprising the following steps: Sludge was inoculated into the anaerobic ammonia oxidation granular sludge reactor at an inoculum concentration of 20-40 g / L. The influent ammonia nitrogen and nitrite nitrogen concentrations were 100-500 mg / L, and the influent nitrogen loading was 3.60 kg-N / m³ for 1-50 days. 3 / d, 7.20 kg-N / m³ for days 51-86 3 The reactor operated for a total of 86 days. Small amounts of excess zero-valent iron (ZFe) were continuously added to the reactor. From days 1 to 20, the ZFe concentration was 1 g / L, added every 2 days; from days 21 to 50, the ZFe concentration was 2 g / L, added every 3 days; from days 51 to 66, the ZFe concentration was 4 g / L, added every 4 days; and from days 67 to 86, the ZFe concentration was 6 g / L, added every 5 days. The final ZFe addition reached 1.5-10 g / g-VSS. After the operation, the iron-rich inclusion anaerobic ammonia oxidation particles were obtained.

2. The iron-rich inclusion anaerobic ammonia oxidation particles prepared by the preparation method of claim 1.

3. The iron-rich inclusion anaerobic ammonium oxidation particles according to claim 2, characterized in that: According to scanning electron microscopy energy dispersive spectroscopy analysis, the iron content on the surface of the iron-rich inclusion anaerobic ammonium oxidation particles is above 30%.

4. The use of the iron-rich inclusion anaerobic ammonia oxidation particles according to claim 2 or 3 in any of the following: (1) Denitrification treatment of high-load nitrogen-containing wastewater; (2) Denitrification treatment of nitrogen-containing wastewater containing heavy metals and / or antibiotics.

5. The application according to claim 4, characterized in that: The denitrification treatment load for the high-load nitrogen-containing wastewater is 30-60 kg-N·m³. -3 ·d -1 .

6. The application according to claim 4, characterized in that: The nitrogen-containing wastewater containing heavy metals and / or antibiotics has a concentration of 50-1000 mg / L for heavy metals and 1-100 mg / L for antibiotics.

7. The application according to claim 6, characterized in that: The heavy metal is at least one of nickel, manganese, iron, chromium, cadmium, copper, zinc, lead, mercury, silver, and arsenic; the antibiotic is at least one of tetracycline, oxytetracycline, sulfamethoxazole, erythromycin, spiramycin, clarithromycin, norfloxacin, and ciprofloxacin.

8. The application according to any one of claims 4-7, characterized in that: In the denitrification treatment of nitrogen-containing wastewater, the inoculum concentration of the iron-rich inclusion anaerobic ammonia oxidation particles is 1-40 g / L.

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