A process for reducing the substrate NO2 - dependence method

Abstract

The present application relates to the field of sewage treatment, in particular to a kind of trivalent iron reduces Anammox autotrophic denitrification process to substrate NO2 ‑ Dependence method, after inoculating Anammox anaerobic sludge to reactor, trivalent iron is introduced into system, Anammox anaerobic sludge is domesticated and cultured again, the ratio of nitrite nitrogen and ammonia nitrogen is reduced, and the hydraulic retention time is adjusted, the demand of Anammox autotrophic denitrification process to substrate NO2 ‑ Is reduced, the problem of high process cost and process equipment procedure complexity when anaerobic ammonia oxidation reaction occurs is solved, and it has important significance for sewage denitrification.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sewage treatment, in particular to a method for reducing the substrate NO2 - dependence of anammox autotrophic denitrification process. BACKGROUND

[0002] Sewage denitrification is still an important problem in global water pollution control. The traditional nitrification-denitrification process requires aeration and sufficient carbon source, consumes a large amount of energy, and has environmental problems such as incomplete denitrification and greenhouse gas emissions.

[0003] Anaerobic ammonium oxidation (Anammox) process is a new type of biological denitrification technology for sewage. Under anaerobic conditions, anaerobic ammonium oxidation bacteria use NH4 + as an electron donor and NO2 - as an electron acceptor to directly generate N2. The application of this technology can save energy and reduce carbon emissions, so it plays an important role in sewage denitrification.

[0004] The application system of Anammox process must contain NH4 + and NO2 - to achieve nitrogen removal, but NO2 - is difficult to accumulate for a long time, so an aerobic nitration process is set before the anaerobic ammonium oxidation reaction to ensure that there is a continuous and appropriate amount of NO2 - to react, which greatly increases the process cost and complexity. Iron ammonia oxidation (Fe(III)-mediated anaerobic ammonium oxidation, Feammox) is a metabolic mechanism that objectively exists in the biochemical cycle of the earth. In the research process, it was found that under anaerobic conditions, NH4 + can be oxidized by the action of microorganisms in the Feammox mechanism while Fe(III) is reduced, but its end product has not been clearly verified, so it cannot be determined whether it can play a role in sewage treatment, especially in denitrification, and its application in sewage denitrification treatment is limited.

[0005] Iron-type denitrification (NDFO) refers to the reduction of nitrogen oxides (NO x - ) to N2 by Fe(II) while generating Fe(III). Feammox and NDFO can exist in a coupled manner, and the Fe(II) and nitrogen oxides generated by Feammox reaction can undergo NDFO reaction under the action of microorganisms. If the two can be effectively coupled, the denitrification efficiency can be further improved.

[0006] From this, researchers began to consider whether to use ferric iron to replace part of NO2 - , directly with NH4 + reaction for wastewater denitrification application, to make up for the problem that the Anammox autotrophic denitrification process cannot achieve the ideal denitrification effect due to the absence of NO2 - The present application aims to provide a method for reducing the dependence of Anammox autotrophic denitrification process on NO2 - , reducing the complexity and cost of wastewater denitrification treatment process, and has a practical positive significance. SUMMARY

[0007] The purpose of the present application is to provide a method for reducing the dependence of Anammox autotrophic denitrification process on substrate NO2 - .

[0008] The technical scheme adopted to achieve the purpose of the present application is:

[0009] Step 1. Inoculating Anammox anaerobic sludge into the reactor

[0010] The Anammox granular sludge is washed with phosphate buffer solution (PBS) for 3 times, and then inoculated into the anaerobic sludge reactor after discarding the supernatant. The MLSS of the Anammox granular sludge is controlled at about 8000mg / L after inoculation.

[0011] Step 2. Introduction of ferric ion

[0012] The deoxygenated water solution is continuously introduced into the Anammox sludge for 20 days of early domestication.

[0013] Further, the ammonia nitrogen content in the deoxygenated water solution is 103mg / L, the nitrite nitrogen content is 137mg / L, the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration is controlled at 1.32, the hydraulic retention time is 8h, and the total nitrogen load is 0.72kg / m 3 / d;

[0014] After the early domestication, ferric ions are introduced into the Anammox granular sludge, and the deoxygenated water solution is continuously introduced for 10 days of continuous domestication.

[0015] Further, the ferric ion release source includes but is not limited to solid iron, and the dosage is calculated based on iron;

[0016] Further, the solid iron source is preferably Fe2O3, and the input form is powder, and the input amount is 20mmol / L (calculated based on Fe).

[0017] Step 3. Domestication and cultivation of Anammox anaerobic sludge

[0018] Gradually increasing the ammonia nitrogen concentration and reducing the nitrite nitrogen concentration in the deoxygenated water solution under the premise of ensuring the nitrogen mass conservation of the matrix, so that the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration gradually decreases, and the deoxygenated water solution is continuously introduced into the Anammox sludge, and the hydraulic retention time is gradually adjusted for continuous domestication.

[0019] (1) After the pre-domestication of steps 1 and 2, the ammonia nitrogen concentration in the original deoxygenated water solution introduced is increased to 114 mg / L, the nitrite nitrogen is reduced to 126 mg / L, and the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration is controlled to be 1.1;

[0020] The hydraulic retention time is adjusted to 24 h, the total nitrogen load is 0.24 kg / m 3 / d, and domestication is performed for 10 days;

[0021] The hydraulic retention time is adjusted to 12 h, the total nitrogen load is 0.45 kg / m 3 / d, and domestication is performed for 10 days;

[0022] The hydraulic retention time is adjusted to 8 h, the total nitrogen load is 0.72 kg / m 3 / d, and domestication is performed for 10 days.

[0023] (2) The ammonia nitrogen concentration in the deoxygenated water solution in (1) is increased to 133 mg / L, the nitrite nitrogen is reduced to 107 mg / L, and the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration is controlled to be 0.8;

[0024] The hydraulic retention time is adjusted to 24 h, the total nitrogen load is 0.24 kg / m 3 / d, and domestication is performed for 10 days;

[0025] The hydraulic retention time is adjusted to 12 h, the total nitrogen load is 0.45 kg / m 3 / d, and domestication is performed for 10 days;

[0026] The hydraulic retention time is adjusted to 8 h, the total nitrogen load is 0.72 kg / m 3 / d, and domestication is performed for 10 days.

[0027] (3) The ammonia nitrogen concentration in the deoxygenated water solution in (2) is increased to 150 mg / L, the nitrite nitrogen is reduced to 90 mg / L, and the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration is controlled to be 0.6;

[0028] The hydraulic retention time is adjusted to 24 h, the total nitrogen load is 0.24 kg / m 3 / d, and domestication is performed for 10 days;

[0029] The hydraulic retention time is adjusted to 12 h, the total nitrogen load is 0.45 kg / m 3 / d, and domestication is performed for 10 days;

[0030] The hydraulic retention time was adjusted to 8 hours, and the total nitrogen load was 0.72 kg / m³. 3 / d, 10 days of acclimatization.

[0031] This means that a method for reducing the impact of Anammox autotrophic denitrification process on the substrate NO2 by introducing ferric iron has been successfully developed. - The method relies on [specific methods] to achieve a total nitrogen removal rate of over 90% in the effluent, thus reducing NO2 [efforts]. - After achieving the desired content, the Anammox autotrophic denitrification process allows for the coexistence of two different denitrification modes: one using NO2... - Another approach is to use ferric iron as an electron acceptor in the system, enabling the Anammox autotrophic denitrification process to operate continuously.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] 1. The ferric iron provided by this invention reduces the impact of Anammox autotrophic denitrification process on substrate NO2. - This method reduces the dependence on substrate NO2 in Anammox's autotrophic denitrification process. - The requirements are as follows: In the original Anammox autotrophic denitrification process, the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration must be at least 1.32:1. With this technical solution, even when the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration is 0.6:1, it will not affect the denitrification effect of the Anammox autotrophic denitrification process in wastewater treatment. After introducing ferric iron, an Anammox autotrophic denitrification process utilizing ferric iron as an electron acceptor is obtained through domestication. This is equivalent to opening up a metabolic mechanism in the Anammox autotrophic denitrification process that conforms to the Feammox iron ammonia oxidation. In particular, after stimulating the potential of Feammox, Feammox is coupled with NDFO, which further improves the total nitrogen removal rate and makes the final product clear. At the same time, it solves the problems of high process cost, complex process equipment and procedures, and unclear Feammox iron ammonia oxidation final product caused by the lack of anaerobic ammonia oxidation reaction.

[0034] 2. The introduction of ferric iron has a positive effect on the denitrification of the Anammox autotrophic denitrification process, which can improve the total nitrogen load capacity of the Anammox autotrophic denitrification process and is of great significance for wastewater denitrification. Attached Figure Description

[0035] Figure 1 This is a graph showing the influent concentrations of ammonia nitrogen and nitrite nitrogen, as well as the total nitrogen removal rate during the wastewater treatment process of this invention. Detailed Implementation

[0036] With reference to the accompanying drawings, the technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0037] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0038] Embodiment 1

[0039] Anammox granular sludge was inoculated into the anaerobic sludge reactor, the Anammox granular sludge was washed with phosphate buffer solution (PBS) for 3 times, and then inoculated into the anaerobic sludge reactor after the supernatant was discarded, and the MLSS of the Anammox granular sludge was controlled at about 8000 mg / L after inoculation.

[0040] The deoxygenated water solution was provided, wherein the ammonia nitrogen was 103 mg / L, the nitrite nitrogen was 137 mg / L, the ratio of the concentration of the nitrite nitrogen to the concentration of the ammonia nitrogen was 1.32, the hydraulic retention time was 8 h, and the total nitrogen load was 0.72 kg / m 3 / d; the water solution was continuously introduced into the Anammox sludge, and the preliminary domestication was performed for 20 days until the total nitrogen removal rate was greater than 85%.

[0041] After the preliminary domestication was completed, 20 mmol / L of Fe2O3 was added into the Anammox granular sludge, the deoxygenated water solution was provided, wherein the ammonia nitrogen was 103 mg / L, the nitrite nitrogen was 137 mg / L, the hydraulic retention time was 8 h, and the total nitrogen load was 0.72 kg / m 3 / d; the water solution was continuously introduced into the Anammox sludge, and the domestication was continued for 10 days, the ammonia nitrogen and the nitrite nitrogen were still removed synchronously, and the total nitrogen removal rate was greater than 85%.

[0042] The concentration of the ammonia nitrogen in the deoxygenated water solution was increased to 114 mg / L, the concentration of the nitrite nitrogen was decreased to 126 mg / L, the ratio of the concentration of the nitrite nitrogen to the concentration of the ammonia nitrogen was 1.1, the hydraulic retention time was adjusted to 24 h, and the total nitrogen load was 0.24 kg / m 3 / d, the domestication was performed for 10 days, the ammonia nitrogen and the nitrite nitrogen were removed synchronously, and the total nitrogen removal rate was greater than 90%. The hydraulic retention time was adjusted to 12 h, the total nitrogen load was 0.45 kg / m 3 / d, the domestication was performed for 10 days, the ammonia nitrogen and the nitrite nitrogen were removed synchronously, and the total nitrogen removal rate was greater than 90%. The hydraulic retention time was adjusted to 8 h, the total nitrogen load was 0.72 kg / m 3 / d, the domestication was performed for 10 days, the ammonia nitrogen and the nitrite nitrogen were removed synchronously, and the total nitrogen removal rate was greater than 90%.

[0043] The ammonia nitrogen concentration in the deoxygenated aqueous solution was then increased to 133 mg / L, and the nitrite nitrogen concentration was reduced to 107 mg / L. At this point, the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration was 0.8. The hydraulic retention time was adjusted to 24 h, and the total nitrogen load was 0.24 kg / m³. 3 / d, after 10 days of acclimatization, ammonia nitrogen and nitrite nitrogen were removed simultaneously, with a total nitrogen removal rate exceeding 90%. The hydraulic retention time was adjusted to 12 hours, and the total nitrogen load was 0.45 kg / m³. 3 / d, after 10 days of acclimatization, ammonia nitrogen and nitrite nitrogen were removed simultaneously, with a total nitrogen removal rate exceeding 90%. The hydraulic retention time was adjusted to 8 hours, and the total nitrogen load was 0.72 kg / m³. 3 / d, after 10 days of acclimatization, ammonia nitrogen and nitrite nitrogen are removed simultaneously, and the total nitrogen removal rate reaches over 90%.

[0044] Continue increasing the ammonia nitrogen concentration in the deoxygenated aqueous solution to 150 mg / L and decreasing the nitrite nitrogen concentration to 90 mg / L. At this point, the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration is 0.6. Adjust the hydraulic retention time to 24 h and the total nitrogen load to 0.24 kg / m³. 3 / d, after 10 days of acclimatization, ammonia nitrogen and nitrite nitrogen were removed simultaneously, with a total nitrogen removal rate exceeding 90%. The hydraulic retention time was adjusted to 12 hours, and the total nitrogen load was 0.45 kg / m³. 3 / d, after 10 days of acclimatization, ammonia nitrogen and nitrite nitrogen were removed simultaneously, with a total nitrogen removal rate exceeding 90%. The hydraulic retention time was adjusted to 8 hours, and the total nitrogen load was 0.72 kg / m³. 3 / d, after 10 days of acclimatization, ammonia nitrogen and nitrite nitrogen are removed simultaneously, and the total nitrogen removal rate reaches over 90%.

[0045] like Figure 1 The figure shows the influent concentrations of ammonia nitrogen and nitrite nitrogen, as well as the total nitrogen removal rate during wastewater treatment. The experimental results indicate that this method can utilize ferric iron to reduce the NO2 content of the Anammox autotrophic denitrification process. - Dependence on NO2, to achieve partial NO2 - Without participating in the reaction, ferric iron can be used as an electron acceptor to acclimatize the Anammox autotrophic denitrification process system. Within the Anammox autotrophic denitrification process system, the metabolic mechanism conforming to Feammox iron ammonia oxidation is obtained through acclimatization. After acclimatization, the final products are clearly defined during wastewater denitrification treatment, and the system can operate sustainably, still achieving the goal of continuous autotrophic denitrification.

[0046] Comparative Example 1

[0047] The Anammox granular sludge was rinsed three times with phosphate-buffered saline (PBS), and the supernatant was discarded before being inoculated into an anaerobic sludge reactor. After inoculation, the MLSS of the Anammox granular sludge was controlled at around 8000 mg / L.

[0048] The deoxygenated water solution with the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration of 1.3, 1.1, 0.8, 0.6 was respectively introduced into the reactor inoculated with Anammox granular sludge, and the total nitrogen removal rate was calculated after 10 days of domestication under different conditions.

[0049] The total nitrogen removal rate after 10 days of domestication is shown in Table 1.

[0050] Table 1

[0051] Ratio of nitrite nitrogen concentration to ammonia nitrogen concentration Hydraulic retention time (h) Total nitrogen load (kg / m 3 / d) Total nitrogen removal rate (%) 1.32 8 0.72 85 1.1 24 0.24 80 0.8 24 0.24 69 0.6 24 0.24 58

[0052] As can be seen from the data in Table 1, the deoxygenated water solution was treated under anaerobic conditions in the reactor inoculated with Anammox granular sludge under the same conditions as in Example 1, and the difference from Example 1 is that no ferric iron was introduced in this process, and no NO2 - was continuously supplemented in the process.

[0053] As can be seen from the data in Table 1, the total nitrogen removal rate can reach 85% when the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration is 1.32, which meets the requirements of nitrogen removal in the industry, but when the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration is reduced to below 1.32, the total nitrogen removal rate decreases significantly, when the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration is 1.1, the total nitrogen removal rate can be maintained at 80%, when the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration is 0.8, the total nitrogen removal rate can only reach 69%, and when the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration is reduced to 0.6, the total nitrogen removal rate is only 58%.

[0054] Compared with Example 1, it can be seen from the total nitrogen removal rate that the Anammox autotrophic denitrification process has a strong dependence on NO2 - , and the reduction of the proportion of NO2 - will directly affect the denitrification effect of the Anammox autotrophic denitrification process, but after the introduction of ferric iron, the Feammox potential in the Anammox autotrophic denitrification process is stimulated, and Feammox is coupled with NDFO, so that the total nitrogen removal rate is significantly improved.

[0055] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for reducing the substrate NO2 - dependence of an Anammox autotrophic denitrification process characterized in that, The method comprises the following steps: Step 1: inoculating Anammox anaerobic sludge into a reactor: after the Anammox granular sludge is cleaned with a cleaning solvent, the supernatant is discarded and inoculated into the anaerobic sludge reactor; Step 2: introduction of ferric ion: the Anammox sludge is continuously fed with the deoxygenated water solution for 20 days of pre-acclimation, and then the ferric ion is introduced into the Anammox granular sludge, and the deoxygenated water solution is continuously fed for 10 days of acclimation; the ammonia nitrogen content in the deoxygenated water solution is 103 mg / L, the nitrite nitrogen content is 137 mg / L, the ratio of the nitrite nitrogen concentration to the ammonia nitrogen concentration is controlled to be 1.32, the hydraulic retention time is 8 h, and the total nitrogen load is 0.72 kg / m 3 / d. Step 3: domestication culture of the Anammox anaerobic sludge: (1) After the pre-acclimation of step 1, 2, the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration in the original deoxygenated water solution is adjusted to 1.1; the hydraulic retention time is adjusted to 24h, the total nitrogen load is 0.24kg / m 3 / d, acclimated for 10 days; the hydraulic retention time is adjusted to 12h, the total nitrogen load is 0.45kg / m 3 / d, acclimated for 10 days; the hydraulic retention time is adjusted to 8h, the total nitrogen load is 0.72kg / m 3 / d, acclimated for 10 days; (2) Adjust the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration in the deoxidized water solution in (1) to 0.8, adjust the hydraulic retention time to 24 h, total nitrogen load to 0.24 kg / m 3 / d, acclimate for 10 days; adjust the hydraulic retention time to 12 h, total nitrogen load to 0.45 kg / m 3 / d, acclimate for 10 days; adjust the hydraulic retention time to 8 h, total nitrogen load to 0.72 kg / m 3 / d, acclimate for 10 days; (3) Adjust the ratio of nitrite nitrogen concentration to ammonia nitrogen concentration in the deoxidized water solution in (2) to 0.6, adjust the hydraulic retention time to 24 h, total nitrogen load to 0.24 kg / m 3 / d, acclimate for 10 days; adjust the hydraulic retention time to 12 h, total nitrogen load to 0.45 kg / m 3 / d, acclimate for 10 days; adjust the hydraulic retention time to 8 h, total nitrogen load to 0.72 kg / m 3 / d, acclimate for 10 days.

2. The Anammox autotrophic denitrification process with reduced iron (III) dependence according to claim 1, characterized in that - The method according to claim 1, characterized in that The cleaning solvent in step 1 is a phosphate buffer solution, and the MLSS of the Anammox granular sludge after inoculation is 8000 mg / L.

3. The Anammox autotrophic denitrification process with reduced iron (III) dependence according to claim 1, characterized in that - The method according to claim 1, characterized in that The trivalent iron ion release source in step 2 includes but is not limited to solid iron, and the dosage is calculated based on iron.

4. The Anammox autotrophic denitrification process with reduced iron (III) dependence according to claim 3, characterized in that - The method according to claim 1 or 2, characterized in that The solid iron source in step 2 is powdered Fe2O3, and the input amount is 20 mmol / L.

5. The process of claim 1 for reducing the substrate NO2 dependence of the Anammox autotrophic denitrification process with Fe(III) - The method is characterized in that The acclimation conditions in Step 2 were a hydraulic retention time of 8 h, a total nitrogen loading of 0.72 kg / m 3 / d.

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