Method for enhancing anaerobic ammonia oxidation denitrification activity based on ammonia carboxylic acid complexing agent

Abstract

The invention relates to the technical field of wastewater treatment, and discloses a method for enhancing anaerobic ammonia oxidation denitrification activity based on an ammonia complexing agent. The method comprises the following steps: (1) taking a sequencing batch reactor as an anaerobic ammonia oxidation reactor, inoculating anaerobic ammonia oxidation sludge, and adding wastewater containing ammonia nitrogen and nitrite nitrogen; and (2) adding an ammonia carboxylic complexing agent-Fe < 3 + > into the anaerobic ammonia oxidation reactor, and carrying out denitrification treatment under an anaerobic condition. According to the method, the solubility and bioavailability of ferric iron are improved by means of the ammonia-carboxyl complexing agent, the uptake capacity of anaerobic ammonium oxidation bacteria on the ferric iron is enhanced, the iron absorption rate can be increased to 50% or above, and the intracellular iron element content can be increased by 1-2 times. The increase of the intracellular iron element content of the anaerobic ammonium oxidation bacteria further promotes the synthesis of key functional enzymes, the denitrification activity is improved and can be improved by 2-5 times compared with the anaerobic ammonium oxidation activity, and the denitrification efficiency of the anaerobic ammonium oxidation system is remarkably enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a method for enhancing anaerobic ammonia oxidation denitrification activity based on an aminocarboxylic acid complexing agent. Background Art

[0002] Oxygen-ammonia oxidation is a process in which anaerobic ammonium-oxidizing bacteria convert nitrite (NO2 - -N) as an electron acceptor, converting ammonia nitrogen (NH4 + -N) is oxidized to nitrogen.

[0003] Compared with the traditional nitrification-denitrification process, anaerobic ammonium oxidation technology can reduce aeration energy consumption by 60%, sludge production by 80%, and does not require an external carbon source. It is an environmentally friendly, energy-saving and efficient new autotrophic biological denitrification technology. Therefore, anaerobic ammonium oxidation technology has broad application prospects in the field of wastewater treatment.

[0004] However, anaerobic ammonium-oxidizing bacteria have a slow growth rate and are highly sensitive to the environment, which makes their microbial activity easily inhibited during actual application, thereby affecting the system's denitrification efficiency and limiting the large-scale engineering application of anaerobic ammonium-oxidizing technology.

[0005] Iron is the most abundant trace element in anaerobic ammonium-oxidizing bacteria and plays an important role in their growth and metabolism. Iron is involved in the formation of functional enzymes such as nitrite reductase (NIR), hydrazine synthase (HZS), and hydrazine dehydrogenase (HDH), which are the main energy sources for the anaerobic ammonium-oxidizing bacteria's anabolism.

[0006] At present, many studies have shown that iron can enhance the denitrification activity of anaerobic ammonium oxidation and strengthen the denitrification efficiency of anaerobic ammonium oxidation systems. However, the bioavailability of iron is limited in anaerobic ammonium oxidation systems. Anaerobic ammonium oxidizing bacteria can only directly absorb dissolved divalent iron (Fe 2+ ), while for dissolved trivalent iron (Fe 3+ ) is insufficient, but in the anaerobic ammonium oxidation system, Fe 2+ Unstable, easily oxidized to Fe 3+ , while Fe 2+ , Fe 3+ It is easy to hydrolyze and form precipitates under neutral and alkaline conditions, resulting in extremely low biological availability of iron and difficulty in maintaining high anaerobic ammonia oxidation denitrification activity.

[0007] Complexone is a kind of Fe 3+ Organic complexing agent with high affinity to Fe 3+ Forms a stable soluble chelate Complexone-Fe 3+ This chelation not only maintains Fe3+ The stable existence of iron prevents its hydrolysis to form hydroxide precipitation, and also promotes the absorption and utilization of iron by microorganisms.

[0008] Therefore, the introduction of aminocarboxylic acid chelating agents into the anaerobic ammonium oxidation system is expected to enhance the anaerobic ammonium oxidizing bacteria's ability to absorb trivalent iron, improve the bioavailability of iron, and thereby enhance the anaerobic ammonium oxidation denitrification activity and strengthen the denitrification efficiency of the anaerobic ammonium oxidation system. Summary of the invention

[0009] The purpose of the present invention is to provide a method for enhancing the anaerobic ammonium oxidation denitrification activity based on an aminocarboxylic acid complexing agent based on the above technical problems.

[0010] In order to achieve the above object, the first aspect of the present invention provides a method for enhancing the anaerobic ammonium oxidation denitrification activity based on an aminocarboxylic acid complexing agent, the method comprising the following steps: (1) Using a sequencing batch reactor as an anaerobic ammonium oxidation reactor, inoculating anaerobic ammonium oxidation sludge, and adding wastewater containing ammonia nitrogen and nitrite nitrogen; (2) Adding aminocarboxylic acid complexing agent-Fe to the anaerobic ammonium oxidation reactor 3+ , denitrification is carried out under anaerobic conditions.

[0011] Preferably, in step (1), the concentration of the inoculated anaerobic ammonium oxidation sludge is 2000 mg SS / L.

[0012] Further preferably, in step (1), the molar ratio of ammonia nitrogen to nitrite nitrogen in the wastewater is 1:1.2.

[0013] Preferably, in step (2), the aminocarboxylic acid complexing agent-Fe 3+ The addition concentration is 12.5~150μmol / L.

[0014] Preferably, in step (2), the aminocarboxylic acid complexing agent-Fe 3+ The preparation method is to complex an aminocarboxylic acid complexing agent and FeCl3 with a molar concentration of 1:1.

[0015] More preferably, in step (2), the conditions for the denitrification treatment meet the following conditions: the temperature of the anaerobic ammonium oxidation reactor is controlled to be 30-35°C, the pH is 7.0-8.5, and the dissolved oxygen concentration is less than 0.1 mg / L.

[0016] The method provided by the present invention also has at least the following beneficial effects: (1) The present invention uses an aminocarboxylic acid complexing agent to maintain the solubility of Fe 3+The stable presence of anaerobic ammonia-oxidizing bacteria is beneficial to avoid the formation of hydroxide precipitation, while enhancing the uptake of trivalent iron by anaerobic ammonia-oxidizing bacteria and improving the bioavailability of iron. The iron absorption rate can be increased to more than 50%, the amount of iron added to the influent can be reduced by more than 70%, and the intracellular iron content can be increased by 1 to 2 times.

[0017] (2) The present invention uses an aminocarboxylic acid complexing agent -Fe 3+ Promoting the synthesis of anaerobic ammonium oxidation functional enzymes can effectively improve the anaerobic ammonium oxidation denitrification activity and the denitrification efficiency of the anaerobic ammonium oxidation system. The activity of key functional enzymes can be increased by more than 1 times, which is 2 to 5 times higher than that of anaerobic ammonium oxidation, and the total nitrogen removal rate can be increased by about 70%.

[0018] (3) The aminocarboxylic acid complexing agent used in the present invention has a small demand, low reagent cost, and small secondary pollution. It is economical, efficient, green and environmentally friendly, and has significant engineering application value.

[0019] (4) The present invention is suitable for the application of anaerobic ammonium oxidation process in the treatment of environments with low iron concentrations such as municipal wastewater and natural surface water. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a graph showing changes in intracellular iron content in the anaerobic ammonium oxidation reactors of Examples 1 to 7 and Comparative Example 1;

[0021] Figure 2 is a graph showing changes in specific anaerobic ammonium oxidation activity (SAA) in the anaerobic ammonium oxidation reactors of Examples 1 to 7 and Comparative Example 1;

[0022] Figure 3 is a graph showing changes in nitrogen concentration in the inlet and outlet water and total nitrogen removal efficiency (NRE) in the anaerobic ammonium oxidation reactor of Comparative Example 2 over the operating time;

[0023] Figure 4 is a graph showing changes in nitrogen concentration in the inlet and outlet water and total nitrogen removal efficiency (NRE) in the anaerobic ammonium oxidation reactor of Comparative Example 3 over the operating time;

[0024] Figure 5 This is a graph showing the change in nitrogen concentration in the inlet and outlet water and the total nitrogen removal efficiency (NRE) in the anaerobic ammonium oxidation reactor of Example 8 over the operating time. DETAILED DESCRIPTION

[0025] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0026] In the present invention, "EDTA" means ethylenediaminetetraacetic acid.

[0027] In the present invention, "SAA" is the specific anaerobic ammonium oxidation activity, which is calculated as follows (wherein "HRT" is the hydraulic retention time):

[0028]

[0029] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, the raw materials are all commercially available.

[0030] Example 1

[0031] This example is used to provide a method for enhancing the anaerobic ammonia oxidation denitrification activity based on an aminocarboxylic acid complexing agent, and the method: (1) A serum bottle with an effective volume of 100 mL was used as an anammox reactor, operated in a sequencing batch mode (i.e., a sequencing batch reactor), inoculated with anammox sludge at a concentration of 2000 mg SS / L, and synthetic wastewater containing ammonia nitrogen and nitrite nitrogen was added to the effective volume;

[0032] The anaerobic ammonium oxidation sludge is uniformly pretreated for about 45 days before inoculation, during which no iron element and aminocarboxylic acid complexing agent are added to the influent, and other components are added normally to eliminate the interference of iron element in the inoculated sludge as much as possible;

[0033] The main components of the synthetic wastewater are as follows: NH4Cl-N 50mg / L, NaNO2 -N 60mg / L, KHCO3 1.0g / L, CaCl2 0.055g / L, MgSO4·7H2O 0.1g / L, KH2PO4 0.025g / L, trace elements 1mL / L;

[0034] Among them, the main components of trace elements include: H3BO3 0.0175mg / L, Na2MoO4·2H2O 0.275mg / L, MnCl2·4H2O 1.2375mg / L, CuSO4·5H2O 0.3125mg / L, CoCl2·6H2O 0.3mg / L, NiCl2·6H2O0.2375mg / L, ZnSO4·7H2O 0.5375mg / L, and Na2EDTA 7.5mg / L.

[0035] (2) Continuously add 12.5 μmol / L of aminocarboxylic acid complexing agent -Fe to the anaerobic ammonium oxidation reactor. 3+ , carry out denitrification under anaerobic conditions and record the operation of the anaerobic ammonium oxidation reactor;

[0036] The aminocarboxylic acid complexing agent-Fe3+ The product is obtained by complexing an aminocarboxylic acid complexing agent with a molar concentration of 1:1 with FeCl3, wherein the aminocarboxylic acid complexing agent is N-triacetic acid;

[0037] The conditions for the denitrification treatment are as follows: the operation time of the anaerobic ammonia oxidation reactor is 7 days, the synthetic wastewater is replaced every 12 hours, the water replacement ratio is set to 100%, the hydraulic retention time is 12 hours, the pH is controlled at 7.5±0.1, the dissolved oxygen concentration is controlled to be less than 0.1 mg / L, the temperature is controlled at 32~34°C by a constant temperature shaker, and the shaker speed is 180 rpm.

[0038] Example 2

[0039] The method of Example 1 was followed, except that in step (2), 25 μmol / L of aminocarboxylic acid complexing agent -Fe was continuously added. 3+ The remaining steps and parameters are the same as in Example 1.

[0040] Example 3

[0041] The method of Example 1 was followed, except that in step (2), 37.5 μmol / L of aminocarboxylic acid complexing agent -Fe was continuously added. 3+ The remaining steps and parameters are the same as those in Example 1.

[0042] Example 4

[0043] The method of Example 1 was followed, except that in step (2), 50 μmol / L of aminocarboxylic acid complexing agent -Fe was continuously added. 3+ The remaining steps and parameters are the same as in Example 1.

[0044] Example 5

[0045] The method of Example 1 was followed, except that in step (2), a concentration of 75 μmol / L of aminocarboxylic acid complexing agent -Fe was continuously added. 3+ The remaining steps and parameters are the same as in Example 1.

[0046] Example 6

[0047] The method of Example 1 was followed, except that in step (2), 100 μmol / L aminocarboxylic acid complexing agent -Fe was continuously added. 3+ The remaining steps and parameters are the same as in Example 1.

[0048] Example 7

[0049] The method of Example 1 was followed, except that in step (2), 150 μmol / L aminocarboxylic acid complexing agent -Fe was continuously added. 3+The remaining steps and parameters are the same as those in Example 1.

[0050] Example 8

[0051] The method of Example 2 is followed, except that in step (1), a sequencing batch reactor with an effective volume of 1 L is used as the anaerobic ammonium oxidation reactor; the ammonia nitrogen content in the synthetic wastewater is 100 mg / L, and the nitrite nitrogen content is 120 mg / L; the conditions for the denitrification treatment are as follows: the operating time of the anaerobic ammonium oxidation reactor is 60 days, the synthetic wastewater is replaced every 8 hours, the water replacement ratio is set to 50%, the hydraulic retention time is 14 hours, and the remaining steps and parameters are the same as those in Example 2.

[0052] Comparative Example 1

[0053] The method of Example 1 was followed, except that in step (2), Fe was not added. 3+ and an aminocarboxylic acid complexing agent, and the remaining steps and parameters are the same as in Example 1.

[0054] Comparative Example 2

[0055] The method of Example 8 was followed, except that in step (2), no Fe was added to the influent. 3+ and an aminocarboxylic acid complexing agent, and the remaining steps and parameters are the same as in Example 8.

[0056] Comparative Example 3

[0057] The method of Example 8 was followed, except that in step (2), EDTA-Fe with a concentration of 25 μmol / L was added to the influent. 3+ , the remaining steps and parameters are the same as those in Example 8;

[0058] Wherein, the EDTA-Fe 3+ Obtained by the complexation of EDTA-2Na and FeCl3 with a molar concentration of 1:1.

[0059] Test Example 1

[0060] After the operation was completed, the intracellular iron content and SAA changes in the anaerobic ammonium oxidation reactors of Examples 1 to 7 and Comparative Example 1 were detected. The results were as follows: Figure 1 and Figure 2 shown.

[0061] Depend on Figure 1 and Figure 2 It can be seen that with the aminocarboxylic acid complexing agent-Fe 3+ With the increase of the dosage concentration, the intracellular iron content and SAA first increased and then stabilized. 3+ When the concentration was lower than 25 μmol / L, the intracellular iron content and SAA increased rapidly with the increase of its concentration; however, when the aminocarboxylic acid complexing agent-Fe3+ When the concentration exceeded 25 μmol / L, the intracellular iron content and SAA changed slowly, indicating that further increasing the aminocarboxylic acid complexing agent-Fe 3+ The concentration has limited effect on the improvement of anaerobic ammonium oxidation denitrification activity. 3+ The appropriate dosage concentration is 25 μmol / L, which can maximize the anaerobic ammonia oxidation denitrification activity while ensuring efficient absorption of iron.

[0062] Moreover, compared with Comparative Example 1, the intracellular iron content in the anaerobic ammonium oxidation reactors described in Examples 1 to 7 of the present invention increased significantly by 32% to 114%, and SAA increased by 2.1 to 4.2 times, indicating that the addition of aminocarboxylic acid complexing agent -Fe 3+ It can effectively enhance the ability of anaerobic ammonium-oxidizing bacteria to absorb trivalent iron, and it utilizes the absorbed iron to synthesize functional enzymes, thereby significantly improving the anaerobic ammonium-oxidizing denitrification activity.

[0063] Test Example 2

[0064] After the operation was completed, the changes in nitrogen concentrations in the inlet and outlet water of the anaerobic ammonium oxidation reactors of Example 8 and Comparative Examples 2 to 3 were detected. Figure 3 , Figure 4 , Figure 5 As shown; the iron content and denitrification efficiency in the anaerobic ammonium oxidation reactor at the end of operation were compared, and the results are shown in Table 1.

[0065] Table 1

[0066] In Table 1, iron absorption rate = 100% - (iron content of outlet water / iron content of inlet water) × 100%.

[0067] It can be seen from the results of Table 1 that at the end of operation, the iron content in the effluent of the anaerobic ammonium oxidation reactors of Comparative Example 2, Comparative Example 3, and Example 8 was 0.3 mg / L, 1.5 mg / L, and 0.7 mg / L, respectively, and the corresponding iron absorption rates were 0%, 3%, and 54%, respectively; and the intracellular iron content of the anaerobic ammonium oxidation reactor of Example 8 of the present invention reached 12.2 mg / g VSS, while that of Comparative Example 2 was 3.1 mg / g VSS, and that of Comparative Example 3 was 4.4 mg / g VSS. These results show that the anaerobic ammonium oxidizing bacteria have a weak ability to absorb trivalent iron, resulting in the iron element added to the anaerobic ammonium oxidation system being mainly lost with the effluent; and the introduction of the aminocarboxylic chelating agent -Fe3+ can effectively promote the uptake of trivalent iron by anaerobic ammonium oxidizing bacteria, significantly improving the bioavailability of iron in the system.

[0068] Depend on Figure 3 , Figure 4 , Figure 5 It can be seen that during operation, in the anaerobic ammonium oxidation reactor of comparative example 2, due to the lack of iron in the influent, the denitrification efficiency was always maintained at a low level; although the influent of the anaerobic ammonium oxidation reactor of comparative example 3 was supplemented with iron, the denitrification efficiency was also low due to the limited uptake capacity of anaerobic ammonium oxidizing bacteria for trivalent iron. In contrast, the denitrification efficiency in the anaerobic ammonium oxidation reactor of Example 8 of the present invention was significantly improved within 0 to 14 days, and stabilized within 15 to 60 days; and, compared with comparative examples 2 and 3, the NRE in Example 8 of the present invention was increased by 73% and 71%, respectively (as shown in Table 1). At the same time, Table 1 shows that the change trend of anaerobic ammonium oxidation denitrification activity is consistent with the denitrification efficiency. In addition, compared with comparative examples 2 and 3, the activities of the key functional enzymes NIR, HZS, and HDH in the anaerobic ammonium oxidation reactor of Example 8 of the present invention were increased by more than 1 times, and SAA was increased by 4.8 times and 3.2 times, respectively. These results indicate that the improvement in the denitrification efficiency in the anaerobic ammonium oxidation reactor of Example 8 of the present invention is mainly due to the enhancement of the anaerobic ammonium oxidation denitrification activity, that is, the aminocarboxylic acid complexing agent -Fe3+ can significantly enhance the anaerobic ammonium oxidation denitrification activity by promoting the activity of key functional enzymes, thereby enhancing the denitrification efficiency of the anaerobic ammonium oxidation system.

[0069] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for enhancing the anaerobic ammonium oxidation denitrification activity based on an aminocarboxylic acid complexing agent, characterized in that: The method comprises the following steps: (1) Using a sequencing batch reactor as an anaerobic ammonium oxidation reactor, inoculating anaerobic ammonium oxidation sludge, and adding wastewater containing ammonia nitrogen and nitrite nitrogen; (2) Adding aminocarboxylic acid complexing agent-Fe to the anaerobic ammonium oxidation reactor 3+ , denitrification is carried out under anaerobic conditions.

2. The method according to claim 1, characterized in that In step (1), the concentration of the inoculated anaerobic ammonium oxidation sludge is 2000 mg SS / L.

3. The method according to claim 1, characterized in that In step (1), the molar ratio of ammonia nitrogen to nitrite nitrogen in the wastewater is 1:1.

2.

4. The method according to claim 1, characterized in that In step (2), the aminocarboxylic acid complexing agent-Fe 3+ The addition concentration is 12.5~150μmol / L.

5. The method according to claim 1, characterized in that: In step (2), the aminocarboxylic acid complexing agent-Fe 3+ The preparation method is to complex an aminocarboxylic acid complexing agent and FeCl3 with a molar concentration of 1:

1.

6. The method according to claim 1, characterized in that In step (2), the conditions for the denitrification treatment are as follows: the temperature of the anaerobic ammonium oxidation reactor is controlled to be 30-35°C, the pH is 7.0-8.5, and the dissolved oxygen concentration is less than 0.1 mg / L.

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