A method for enhancing anaerobic ammonium oxidation denitrification based on the synergistic regulation of calcium ions and inorganic carbon.

Abstract

This invention discloses a method for enhancing anaerobic ammonium oxidation denitrification based on the synergistic regulation of calcium ions and inorganic carbon. By systematically setting calcium ion and inorganic carbon concentration gradients to study the synergistic effect, the influence of both on the denitrification performance of Anammox is revealed. A method for regulating the dosage of calcium ions and inorganic carbon to improve the denitrification rate in the Anammox system is constructed. Finally, the method for determining the calcium ion and inorganic carbon dosage is determined. 2+ Concentration of 350 mg / L, HCO3 ‑ At a concentration of 1 g / L, the denitrification rate in the Anammox system can be greatly improved; the conclusions of this invention are universal and feasible, providing a scientific basis for subsequent applications.

Description

Technical Field

[0001] This invention relates to the field of anaerobic ammonia oxidation denitrification processes, and more particularly to a method for enhancing anaerobic ammonia oxidation denitrification based on the synergistic regulation of calcium ions and inorganic carbon. Background Technology

[0002] Calcium ions and inorganic carbon are both important factors affecting the nitrogen removal performance of anammox (anammox) oxidation. Current technologies have only studied the effects of calcium ions and inorganic carbon as single factors. However, at high calcium ion concentrations (e.g., >350 mg / L), different inorganic carbon concentrations result in varying nitrogen removal performance. Currently, there is a lack of universally applicable and feasible technical solutions to improve Anammox performance based on these two factors. Therefore, this invention aims to provide a method for enhancing Anammox nitrogen removal based on the synergistic regulation of calcium ions and inorganic carbon, thereby addressing this problem. This invention systematically sets calcium ion and inorganic carbon concentration gradients to study their synergistic effect on the Anammox nitrogen removal rate, revealing the synergistic effect of calcium ions and inorganic carbon on Anammox nitrogen removal performance, determining the optimal calcium ion and inorganic carbon concentrations, and establishing a method for enhancing Anammox nitrogen removal through the synergistic regulation of calcium ions and inorganic carbon.

[0003] Ammonia nitrogen (NH4) + -N) is an important nitrogen pollutant in my country's water bodies, and excessive NH4+... + -N emissions into natural water bodies have a significant impact on the environment and human health. NH4 + Nitrogen removal has always been one of the main tasks of water environment protection in my country. Compared with nitrification-denitrification biological nitrogen removal processes, the Anammox process is a novel autotrophic nitrogen removal process that does not require an external carbon source or aeration. Traditional Anammox processes operate under anaerobic conditions, using NH4+ as the nitrogen source. + -N and nitrite nitrogen (NO2) - Using nitrogen (N-N) as a substrate, it is converted into nitrogen gas for removal. Compared with the traditional nitrification-denitrification process, Anammox has advantages such as no need for external organic carbon sources, low sludge yield, and energy saving, and has been widely used in the treatment of high ammonia nitrogen wastewater such as landfill leachate and sludge digestion liquid.

[0004] Calcium ions and inorganic carbon are key factors affecting the Anammox process. Inorganic carbon participates in the energy metabolism of Anammox bacteria and is the sole carbon source for the synthesis of cellular materials. Its concentration directly determines the bacterial proliferation rate and affects pH stability during the reaction. Calcium ions participate in the regulation of key enzyme activity in the bacterial community and promote the cross-linking of proteins and polysaccharides in extracellular polymers (EPS) through bridging, enhancing anammox sludge granulation and reducing sludge loss. Existing research on how these two factors affect Anammox denitrification performance is inconsistent. This is because, in the Anammox system, calcium ions and inorganic carbon interact through processes such as influencing pH and forming calcium carbonate. However, existing studies only investigate the individual effects of calcium ions or inorganic carbon on Anammox denitrification, neglecting their synergistic effects. This leads to inconsistent and even contradictory conclusions, making it impossible to develop methods to improve Anammox performance based on calcium ions or inorganic carbon, or to establish universally applicable and feasible technical solutions for improving Anammox performance based on calcium ions or inorganic carbon. Therefore, in-depth research into the synergistic mechanism of calcium ions and inorganic carbon, and revealing their comprehensive impact on Anammox denitrification performance, is key to constructing an efficient and stable Anammox system and optimizing the denitrification process.

[0005] Wang Xiaojun, Shi Huiqun, Wu Junbin, et al. A method for rapidly cultivating anaerobic ammonia oxidation granular sludge. Shanghai: CN202211068168.7 [P]. 2023-06-27. This patent document discloses a method for rapidly cultivating Anammox granular sludge, aiming to generate crystalline precipitates (such as struvite, hydroxyapatite, calcium carbonate, etc.) by adding reactants that match the anions and cations of wastewater, promoting the co-growth of Anammox bacteria and crystals to form granular sludge, and simultaneously achieving sludge stabilization and wastewater treatment. Its core is to strengthen bacterial aggregation through crystal precipitation, solving the problem of easy sludge loss in traditional Anammox processes, while also partially recovering resources. This method only studies the effects of single concentrations of calcium and magnesium ions on granular sludge aggregation, but does not study the effect of calcium ion concentration on the denitrification rate, and therefore cannot adjust the denitrification performance accordingly.

[0006] Liu Jianyong, Yang Shoukuan. A method for in-situ formation of granular sludge in a high-load anaerobic ammonia oxidation reactor for leachate treatment. Fujian Province: CN202210262285.0 [P]. 2023-12-22. This patent document discloses a method for in-situ formation of granular sludge in a high-load Anammox reactor for leachate treatment. The patent focuses on utilizing the high alkalinity and calcium ions of the leachate itself to promote in-situ precipitation of calcium carbonate by controlling reactor conditions. This calcium carbonate serves as the "inorganic core" of Anammox bacteria, accelerating sludge granulation and maintaining high-load operation (≥30g N / L / d). Its core lies in utilizing the naturally high calcium content of the leachate, combining with calcium ions in an alkaline environment to form a precipitate, simplifying the process and reducing costs. This method is suitable for high-calcium leachate, focusing on using the leachate to promote calcium carbonate formation and accelerate sludge granulation, but it does not investigate the impact on denitrification performance.

[0007] Although the Anammox process can be carried out under anaerobic conditions, using NH4 + -N and NO2 - -N reacts as a substrate to convert into nitrogen gas, but current technologies only set the calcium ion concentration or inorganic carbon concentration, without considering their interaction, leading to a chain of negative effects. When the calcium ion concentration is too high (e.g., >500 mg / L) and the inorganic carbon is insufficient (e.g., <100 mg / L): excess calcium ions cannot combine with bicarbonate to form calcium carbonate, but instead combine with the carboxyl groups (-COOH) in the extracellular polymeric substances (EPS) of Anammox bacteria, causing EPS structure destruction. The sludge particles disintegrate due to loss of EPS binding force (particle size decreases from 120 μm to 40 μm). The bacterial community is exposed to the water and easily lost with the effluent. The remaining bacteria, due to insufficient inorganic carbon (shortage of carbon source supply), experience a decrease in metabolic rate, with denitrification efficiency dropping from 90% to below 60%, and continuing to deteriorate. Furthermore, adjusting the inorganic carbon concentration only by supplementing bicarbonate, ignoring the synergistic effect of calcium ions, triggers a series of chain problems. When bicarbonate levels are excessive (e.g., >400 mg / L) and calcium ion levels are insufficient (e.g., <150 mg / L): the cross-linking of polysaccharides and proteins in sludge EPS lacks calcium ion bridging, resulting in a loose structure and deteriorated settling performance. Insufficient bacterial density makes it unable to cope with normal nitrogen loads (e.g., 200 mg / L NH4+). + The denitrification efficiency remains below 70% due to the presence of calcium ions and inorganic carbon (-N). To address the aforementioned shortcomings in existing technologies caused by individually controlling calcium ion or inorganic carbon concentrations, the present invention aims to provide a universal and feasible method for synergistic regulation of calcium ions and inorganic carbon to enhance Anammox denitrification performance. Summary of the Invention

[0008] This invention provides a method for enhancing anaerobic ammonium oxidation (Anammox) denitrification based on the synergistic regulation of calcium ions and inorganic carbon.

[0009] This invention, based on the different effects of calcium ions and inorganic carbon on the denitrification efficiency of Anammox bacteria, constructs a method for synergistic regulation of Anammox denitrification by calcium ions and inorganic carbon. By detecting the concentrations of ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, calcium ions, and inorganic carbon in the reactor effluent, the nitrogen degradation rate of the Anammox process in the reactor is further calculated, thereby determining the appropriate dosage of calcium ions and inorganic carbon.

[0010] The technical solution of the present invention is as follows:

[0011] A method for enhancing anaerobic ammonia oxidation denitrification based on the synergistic regulation of calcium ions and inorganic carbon includes:

[0012] Pretreated anaerobic ammonia oxidation sludge was inoculated into a bioreactor. Nitrogenous wastewater was introduced, and calcium and inorganic carbon sources were added. The hydraulic retention time of the wastewater in the reactor was 22 hours, the pH was maintained at 7.7±0.2, and the reactor temperature was controlled at 30±0.2℃. Water samples were taken to measure the NH4+ in the reactor effluent. + -N, NO2 - -N, NO3 - -N concentration, calculate the nitrogen degradation rate of anaerobic ammonia oxidation in the reactor;

[0013] in,

[0014] Bioreactors can be made of glass;

[0015] The pretreatment method for anaerobic ammonia oxidation sludge is as follows: wash the anaerobic ammonia oxidation sludge with 0.9wt% NaCl solution, centrifuge at 5000rpm for 10min, and repeat the washing 3 times; before sludge inoculation, purge with argon gas until dissolved oxygen is below 0.5mg / L;

[0016] The preferred inoculum volume of anaerobic ammonia oxidation sludge is 10% of the effective volume of the reactor;

[0017] Nitrogen-containing wastewater, such as landfill leachate and sludge digestion liquid, is high in ammonia nitrogen. Before being introduced into the reactor, the nitrogen-containing wastewater is purged with argon gas until the dissolved oxygen level is below 0.5 mg / L.

[0018] Ideally, 90% of the effective volume of the reactor should be replaced each time the water is changed;

[0019] The preferred calcium source is CaCl2, Ca 2+ The concentration in wastewater is 350–640 mg / L, preferably 350 mg / L;

[0020] The preferred inorganic carbon source is NaHCO3 or HCO3. - The concentration in wastewater is 0.5–1 g / L, preferably 1 g / L.

[0021] The beneficial effects of this invention are as follows:

[0022] Existing studies have focused on only one factor, calcium ions or inorganic carbon, neglecting their interaction in the Anammox system, leading to inconsistent or even contradictory conclusions. For example, the effects of the same calcium ion concentration on denitrification under different inorganic carbon conditions have yielded opposite results.

[0023] To address the problem of decreased denitrification rates in existing Anammox systems due to a lack of synergistic matching between calcium ion and inorganic carbon concentrations, this invention provides a method for enhancing Anammox denitrification based on the synergistic regulation of calcium ion and inorganic carbon concentrations. This invention studies the synergistic effect by systematically setting calcium ion and inorganic carbon concentration gradients, revealing the influence of both on Anammox denitrification performance, and constructing a method for regulating the dosage of calcium ions and inorganic carbon to improve the denitrification rate in the Anammox system.

[0024] Finally determined Ca 2+ Concentration of 350 mg / L, HCO3 - At a concentration of 1 g / L, the denitrification rate in the Anammox system can be significantly increased. The conclusions of this invention are universal and feasible, providing a scientific basis for subsequent applications. Attached Figure Description

[0025] Figure 1 : Denitrification rate diagram of Anammox reactors with different calcium ion and inorganic carbon concentrations in the examples.

[0026] Figure 2 : Graph showing the calcium ion degradation rate in Anammox reactors with different calcium ion and inorganic carbon concentrations in the examples.

[0027] Figure 3 : Inorganic carbon degradation rate diagram of Anammox reactor with different calcium ion and inorganic carbon concentrations in the examples. Detailed Implementation

[0028] The present invention is further described below through specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0029] The Anammox granular sludge used in the following examples was obtained from an upflow anaerobic sludge blanket reactor operated in our laboratory. The effective reactor volume was 5L, and the influent nitrogen-containing substrate was NH4. + -N: 200mg / L, NO2 - -N: 264mg / L, environmental operating parameters are: temperature: 30±2℃, pH: 7.2±0.3, dissolved oxygen <0.5mg / L, HRT for each cycle is 6h, continuous and stable operation for more than 3 months, and nitrogen removal efficiency is stable at over 90%.

[0030] Example 1

[0031] A method for synergistic regulation of Anammox deamination by calcium ions and inorganic carbon includes the following steps:

[0032] (1) Reactor operation: Anammox granular sludge is added to the glass reactor device to start the Anammox process. Specifically, an anaerobic reactor is used with an effective volume of 500 mL. The reactor is placed in a constant temperature magnetic stirring water bath.

[0033] (2) Inoculation: The Anammox sludge was washed with 0.9% NaCl solution and centrifuged at 5000 rpm for 10 min. The washing process was repeated three times. Before inoculation, the sludge was purged with argon gas until the dissolved oxygen was below 0.5 mg / L. The treated sludge was inoculated into the bioreactor at a volume of 10% of the effective volume of the reactor, and the mixed liquor suspended solids (MLSS) concentration of the inoculum was 13.65 g·L⁻¹. -1 .

[0034] (3) Influent: Simulated nitrogen-containing wastewater with different calcium ion and inorganic carbon concentrations was added to nine bioreactors (R1, R2, R3, R4, R5, R6, R7, R8, R9). The calcium ion concentrations were 0, 350, 640, 0, 350, 640, 0, 350, 640 mg / L, respectively; HCO3 - The concentrations were 500, 500, 500, 750, 750, 750, 1000, 1000, and 1000 mg / L. The hydraulic retention time of the wastewater in the reactor was 22 h. The pH of the nitrogen-containing wastewater was maintained at 7.7 ± 0.2. Before the experiment, the wastewater was purged with argon gas, and the dissolved oxygen was below 0.5 mg / L. The reactor temperature was controlled at 30 ± 0.2℃, and the magnetic stirrer speed was 450 r / min. 90% of the effective reactor volume was replaced each time the water was changed.

[0035] (4) The simulated nitrogen-containing wastewater contained 763.6 mg / L of ammonia chloride (NH4Cl), 1300.6 mg / L of sodium nitrite (NaNO2), 100.6 mg / L of calcium chloride (CaCl2) prepared according to experimental requirements, 30 mg / L of potassium dihydrogen phosphate (KH2PO4), 70 mg / L of magnesium chloride (MgCl2·6H2O), 1 mL / L of sodium bicarbonate (NaHCO3) prepared according to experimental requirements, and 1 mL / L of trace element A and trace element B.

[0036] (5) The components of trace element A solution are as follows: ferric sulfate (FeSO4·7H2O) 5000 mg / L and ethylenediaminetetraacetic acid (EDTA) 5000 mg / L.

[0037] (6) The components of trace element B solution are as follows: ethylenediaminetetraacetic acid (EDTA) 15000 mg / L, zinc sulfate (ZnSO4·7H2O) 430 mg / L, cobalt chloride (CoCl2·6H2O) 240 mg / L, manganese chloride (MnCl2·4H2O) 990 mg / L, copper sulfate (CuSO4·5H2O) 250 mg / L, sodium molybdate (Na2MoO4·2H2O) 220 mg / L, boric acid (H3BO3) 14 mg / L, nickel chloride (NiCl2·6H2O) 190 mg / L and sodium selenate (NaSeO4·10H2O) 210 mg / L.

[0038] (7) Sampling: Turn off the magnetic stirrer and let it settle for 10 minutes. Take water samples through the sampling port once every 24 hours for measurement and analysis.

[0039] (8) Measure the NH4 content in the effluent from different reactors. + -N, NO2 - -N, NO3 - -N, calcium ion and inorganic carbon concentration. For example... Figures 1-3 The graphs show the calculated nitrogen degradation rate, calcium ion degradation rate, and inorganic carbon degradation rate in the Anammox reactor process. This demonstrates that calcium ions and inorganic carbon are crucial factors influencing the efficient and stable operation of the Anammox process, and that they synergistically regulate the nitrogen removal rate. Based on this method, an optimal method for enhancing Anammox nitrogen removal through the synergistic regulation of calcium ions and inorganic carbon was established: a calcium ion concentration of 350 mg / L and HCO3- concentrations of... - At a concentration of 1 g / L (R8 group), the denitrification rate was higher and more stable than other reactors.

Claims

1. A method for enhancing anaerobic ammonium oxidation denitrification based on the synergistic regulation of calcium ions and inorganic carbon, characterized in that, The method includes: Pretreated anaerobic ammonia oxidation sludge was inoculated into a bioreactor. Nitrogenous wastewater was introduced, and calcium and inorganic carbon sources were added. The hydraulic retention time of the wastewater in the reactor was 22 hours, the pH was maintained at 7.7±0.2, and the reactor temperature was controlled at 30±0.2℃. Water samples were taken to measure the NH4+ in the reactor effluent. + -N, NO2 - -N, NO3 - -N concentration, calculate the nitrogen degradation rate of anaerobic ammonia oxidation in the reactor; in, Calcium source is Ca 2+ The estimated dosage for addition to wastewater is 350–640 mg / L; Inorganic carbon source with HCO3 - The recommended dosage for addition to wastewater is 0.5–1 g / L.

2. The method for enhanced anaerobic ammonium oxidation denitrification based on the synergistic regulation of calcium ions and inorganic carbon as described in claim 1, characterized in that, The pretreatment method for anaerobic ammonia oxidation sludge is as follows: wash the anaerobic ammonia oxidation sludge with 0.9wt% NaCl solution, centrifuge at 5000rpm for 10min, and repeat the washing 3 times; before sludge inoculation, purge with argon gas until the dissolved oxygen is below 0.5mg / L.

3. The method for enhanced anaerobic ammonium oxidation denitrification based on the synergistic regulation of calcium ions and inorganic carbon as described in claim 1, characterized in that, The inoculation volume of anaerobic ammonia oxidation sludge is 10% of the effective volume of the reactor.

4. The method for enhanced anaerobic ammonium oxidation denitrification based on the synergistic regulation of calcium ions and inorganic carbon as described in claim 1, characterized in that, Each time the water is changed, 90% of the effective volume of the reactor should be replaced.

5. The method for enhanced anaerobic ammonium oxidation denitrification based on the synergistic regulation of calcium ions and inorganic carbon as described in claim 1, characterized in that, Calcium source is Ca 2+ The dosage added to the wastewater is calculated to be 350 mg / L; the inorganic carbon source is HCO3. - The calculated addition amount in wastewater is 1 g / L.

6. The method for enhanced anaerobic ammonium oxidation denitrification based on the synergistic regulation of calcium ions and inorganic carbon as described in claim 1, characterized in that, The calcium source is CaCl2, and the inorganic carbon source is NaHCO3.

7. The method for enhanced anaerobic ammonium oxidation denitrification based on the synergistic regulation of calcium ions and inorganic carbon as described in claim 1, characterized in that, Nitrogenous wastewater is: landfill leachate or sludge digestion liquid; before being introduced into the reactor, the nitrogenous wastewater is purged with argon gas until the dissolved oxygen is below 0.5 mg / L.

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