Method for wastewater treatment based on interspecies electron transfer

Abstract

The application provides a wastewater treatment method based on interspecies electron transfer, and belongs to the technical field of wastewater treatment. The wastewater treatment method based on interspecies electron transfer comprises the following steps: introducing wastewater to be treated into a wastewater treatment device, wherein the wastewater treatment device comprises ammonia-oxidizing bacteria, carbon-fixing bacteria and sulfate-reducing bacteria; under anaerobic conditions, in the wastewater treatment device, the ammonia-oxidizing bacteria oxidize ammonia nitrogen in the wastewater to be treated as an electron donor to generate an oxidation reaction, the carbon-fixing bacteria reduce inorganic carbon in the wastewater to be treated as an electron acceptor to generate a reduction reaction, and the sulfate-reducing bacteria are used to combine the ammonia-oxidizing bacteria and the carbon-fixing bacteria by using interspecies electron transfer capacity of the sulfate-reducing bacteria, so that the wastewater to be treated is subjected to denitrification through metabolic interaction among multiple strains, and treated wastewater is obtained.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a wastewater treatment method based on interspecies electron transfer. Background Technology

[0002] Biological denitrification of wastewater is an important secondary treatment process in wastewater treatment plants. It typically utilizes nitrification-denitrification reactions, promoting the oxidation of ammonia nitrogen to nitrate nitrogen through aeration, and using the carbon source in the influent to carry out denitrification reactions. However, it has problems such as high energy consumption and high treatment costs. At the same time, the nitrification and denitrification reactions produce a large amount of greenhouse gases, especially nitrous oxide, which is a major contributor to the carbon footprint of wastewater treatment plants.

[0003] Traditional anaerobic ammonia oxidation (ANAO) processes can save 50-60% of aeration energy consumption, do not require organic carbon sources, and are an energy-saving and cost-effective wastewater treatment process for nitrogen removal. It uses ammonia nitrogen as an electron donor and nitrite as an electron acceptor to achieve the nitrogen removal reaction. The stable acquisition of nitrite is one of the important factors limiting the effectiveness of traditional ANAO reactions. Extensive research has been conducted in recent years on achieving nitrite accumulation based on short-cut nitrification or partial denitrification reactions, but problems such as unstable operation and complex control technologies still exist. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a wastewater treatment method based on interspecies electron transfer, aiming to at least partially solve these problems. The specific technical solution provided by this invention is as follows.

[0005] According to an embodiment of the present invention, a wastewater treatment method based on interspecies electron transfer is provided, comprising: introducing wastewater to be treated into a wastewater treatment device, the wastewater treatment device including ammonia-oxidizing bacteria, carbon-fixing bacteria and sulfate-reducing bacteria; under anaerobic conditions, in the wastewater treatment device, ammonia-oxidizing bacteria use ammonia nitrogen in the wastewater to be treated as an electron donor to undergo an oxidation reaction, and carbon-fixing bacteria use inorganic carbon in the wastewater to be treated as an electron acceptor to undergo a reduction reaction; utilizing the interspecies electron transfer capability of sulfate-reducing bacteria to combine ammonia-oxidizing bacteria and carbon-fixing bacteria, thereby denitrifying the wastewater to be treated through metabolic interactions between multiple bacterial species, to obtain treated wastewater.

[0006] In this embodiment of the invention, the wastewater treatment method based on interspecies electron transfer provided by the present invention utilizes the interspecies electron transfer capability of sulfate-reducing bacteria to combine ammonia-oxidizing bacteria and carbon-fixing bacteria. Through metabolic interactions among multiple bacterial species, wastewater is treated. This method can treat inorganic wastewater without the need for additional organic carbon sources, reducing wastewater treatment costs and lowering operating energy consumption. It is energy-saving and emission-reducing, does not require aeration, saves energy, has a fast denitrification rate, and can also cause carbon fixation reactions during wastewater treatment, thus achieving carbon emission reduction. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of a wastewater treatment device in one embodiment of the present invention;

[0008] Figure 2 This is a graph showing the ammonia nitrogen test results in wastewater in Example 1 of the present invention;

[0009] Figure 3 This is a graph showing the test results of nitrate nitrogen in wastewater in Example 1 of the present invention;

[0010] Figure 4 This is a graph showing the test results of inorganic carbon in wastewater in Example 1 of the present invention.

[0011] Explanation of reference numerals in the attached figures:

[0012] 100—Water inlet unit;

[0013] 200—Anaerobic ammonia oxidation reactor; 201—Inlet pump; 202—Reflux pump;

[0014] 300—Water outlet unit;

[0015] 400—Gas collection unit. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0017] To address the problems of high energy consumption, high operating costs, and high carbon emissions in existing wastewater denitrification processes, this invention proposes a wastewater treatment method based on interspecies electron transfer.

[0018] Interspecies electron transport (IET) is an important interaction mechanism among microorganisms, with significant implications for geochemical cycles and environmental remediation. Direct interspecies electron transport (DIET) is a newly discovered intermicrobial electron transport pathway with higher efficiency than traditional interspecies hydrogen / formic acid transport, providing a new perspective for studying microbial mutualism. Microorganisms obtain energy through extracellular electron transport (EET), utilizing redox proteins, electron mediators, or nanowires to transfer intracellularly generated electrons to extracellular electron acceptors or to transfer electrons from extracellular electron donors to intracellular sources. This electron transport process is not only crucial for microbial energy metabolism but also has broad application potential in environmental remediation and biofuel production. Some sulfate-reducing bacteria (SRBs), such as *Desulfovibrio*, possess interspecies electron transport capabilities, utilizing conductive flagella (e-pili) and cytochrome c (Cytc) to achieve extracellular electron transfer.

[0019] Based on this, the present invention provides a wastewater treatment method based on interspecies electron transfer. This method utilizes the extracellular electron transfer capacity of sulfate-reducing bacteria (SRB), using ammonia nitrogen as an electron donor and inorganic carbon as an electron acceptor, to achieve a nitrogen removal reaction in wastewater. This process involves metabolic interactions among various bacteria, including ammonia-oxidizing bacteria, sulfate-reducing bacteria, and carbon-fixing bacteria. Compared to nitrification-denitrification and traditional anaerobic ammonia oxidation reactions, this method requires no aeration or organic carbon source, instead undergoing a biological carbon fixation reaction. This saves energy and chemical inputs, and achieves carbon emission reduction, potentially enabling wastewater treatment plants to achieve negative carbon emissions.

[0020] Specifically, according to an embodiment of the present invention, a wastewater treatment method based on interspecies electron transfer is provided, comprising: introducing wastewater to be treated into a wastewater treatment device, the wastewater treatment device including ammonia-oxidizing bacteria, carbon-fixing bacteria and sulfate-reducing bacteria; under anaerobic conditions, in the wastewater treatment device, ammonia-oxidizing bacteria use ammonia nitrogen in the wastewater to be treated as an electron donor to undergo an oxidation reaction, and carbon-fixing bacteria use inorganic carbon in the wastewater to be treated as an electron acceptor to undergo a reduction reaction; utilizing the interspecies electron transfer ability of sulfate-reducing bacteria to combine ammonia-oxidizing bacteria and carbon-fixing bacteria, so as to denitrify the wastewater to be treated through metabolic interactions between multiple bacterial species, thereby obtaining treated wastewater.

[0021] In this embodiment of the invention, the wastewater treatment method based on interspecies electron transfer provided by the present invention utilizes the interspecies electron transfer capability of sulfate-reducing bacteria to combine ammonia-oxidizing bacteria and carbon-fixing bacteria. Through metabolic interactions among multiple bacterial species, wastewater is treated. This method can treat inorganic wastewater without the need for additional organic carbon sources, reducing wastewater treatment costs and lowering operating energy consumption. It is energy-saving and emission-reducing, does not require aeration, saves energy, has a fast denitrification rate, and can also cause carbon fixation reactions during wastewater treatment, thus achieving carbon emission reduction.

[0022] Specifically, utilizing the interspecies electron transfer capacity of sulfate-reducing bacteria to combine ammonia-oxidizing bacteria and carbon-fixing bacteria involves: sulfate-reducing bacteria using the organic carbon released by carbon-fixing bacteria and the sulfate in the wastewater to be treated for proliferation; simultaneously, sulfate-reducing bacteria exert their interspecies electron transfer capacity, enabling oxidation and reduction reactions to occur synergistically, achieving multi-species interaction among ammonia-oxidizing bacteria, carbon-fixing bacteria, and sulfate-reducing bacteria. The sulfate-reducing bacteria's interspecies electron transfer capacity includes: receiving electrons released by the oxidation reaction of ammonia-oxidizing bacteria through their conductive flagella and cytochrome c, and transferring these electrons to the carbon-fixing bacteria for reduction reactions.

[0023] According to embodiments of the present invention, ammonia-oxidizing bacteria are introduced through anaerobic ammonia-oxidizing sludge; sulfate-reducing bacteria are introduced through anaerobic digestion sludge; and carbon-fixing bacteria are introduced through a combination of anaerobic ammonia-oxidizing sludge and anaerobic digestion sludge. Different microorganisms are introduced by introducing different types of sludge into the wastewater treatment device. Specifically, the introduced ammonia-oxidizing bacteria oxidize ammonia nitrogen in the wastewater to nitrogen gas; the introduced carbon-fixing bacteria convert inorganic carbon in the wastewater into intracellular organic matter, which is then released into the wastewater for further utilization and proliferation by other microorganisms; and the introduced sulfate-reducing bacteria reduce sulfate in the wastewater to reduced sulfides (such as sulfide ions or elemental sulfur), promoting the sulfur cycle and simultaneously utilizing interspecies electron transfer capabilities to transfer electrons between ammonia-oxidizing bacteria and carbon-fixing bacteria, promoting the synergistic occurrence of denitrification oxidation and carbon reduction reactions in the wastewater.

[0024] According to embodiments of the present invention, the mass ratio of anaerobic ammonia oxidation sludge to anaerobic digestion sludge in the wastewater treatment device is 1:1, which helps maintain the balance of the microbial community in the wastewater treatment device. The ammonia-oxidizing bacteria and some carbon-fixing bacteria in the anaerobic ammonia oxidation sludge can cooperate with the sulfate-reducing bacteria and another portion of carbon-fixing bacteria in the anaerobic digestion sludge. The total sludge concentration in the wastewater treatment device is 5-7 g / L, ensuring a sufficient number of microorganisms to treat the pollutants in the wastewater. Within this concentration range, microorganisms have sufficient contact opportunities with the pollutants in the wastewater. If the sludge concentration is too high, it may cause sludge bulking, leading to sludge loss and affecting the treatment effect of the wastewater. Simultaneously, excessively high sludge concentration may also cause blockage of the treatment device, increasing equipment maintenance costs. The total sludge age in the wastewater treatment device is 30-60 days. For anaerobic ammonia-oxidizing bacteria, their growth rate is relatively slow. A longer sludge age provides them with sufficient time to grow and reproduce. For sulfate-reducing bacteria, their growth also requires a certain amount of time to adapt to the wastewater environment and function. An appropriate sludge age allows microorganisms to transition from the adaptation phase to the logarithmic growth phase within the treatment plant, fully utilizing the sulfate in the wastewater for metabolic activities, reducing sulfate to hydrogen sulfide. Carbon-fixing bacteria also benefit from a longer sludge age. Their process of synthesizing organic carbon compounds from inorganic carbon is relatively complex and requires time to accumulate sufficient energy and matter. Furthermore, the influent quality and quantity of wastewater treatment plants may fluctuate. A longer sludge age allows for greater adaptability of the microbial community.

[0025] According to embodiments of the present invention, the dissolved oxygen concentration in the wastewater treatment device is ≤0.05 mg / L. Nitrogen stripping pretreatment can be used to maintain low dissolved oxygen conditions (≤0.05 mg / L) in the reactor influent. Ammonia-oxidizing bacteria are strictly anaerobic microorganisms, and high dissolved oxygen concentrations inhibit their activity. When the dissolved oxygen concentration is ≤0.05 mg / L, suitable survival conditions are provided for ammonia-oxidizing bacteria, enabling them to normally convert ammonia nitrogen into nitrogen gas. For sulfate-reducing bacteria, a low dissolved oxygen environment is conducive to their proliferation and interspecies electron transfer function. For carbon-fixing bacteria, they can utilize carbon dioxide or other inorganic carbon sources for growth under anaerobic conditions; low dissolved oxygen concentrations ensure they function in their suitable ecological niches, thereby promoting the stability of the entire microbial ecosystem. The oxidation-reduction potential in the wastewater treatment device is maintained between -140 and -60 mV. Oxidation-reduction potential is an important indicator of microbial activity. By monitoring and maintaining the oxidation-reduction potential, the growth and metabolic state of microorganisms in the wastewater treatment device can be directly understood. If the oxidation-reduction potential deviates from this range, it means that the microbial community has been disturbed, for example, by being impacted by toxic or harmful substances or by a disruption of the balance between microorganisms. In this case, the oxidation-reduction potential can be restored by adjusting the influent water quality or adding nutrients, thereby ensuring the normal activity of the microorganisms and maintaining the stable operation of the wastewater treatment plant.

[0026] According to embodiments of the present invention, the hydraulic retention time of the wastewater treatment device is 1-2 days, ensuring sufficient time for microorganisms and wastewater to fully contact and react. The decomposition of organic matter in wastewater, whether through anaerobic digestion or other microbial metabolic activities, requires a certain amount of time. The metabolic activities of microorganisms such as ammonia-oxidizing bacteria, sulfate-reducing bacteria, and carbon-fixing bacteria each have their own timescales. This time range matches the growth cycle and metabolic reaction rate of these microorganisms, allowing them to grow, reproduce, and metabolize normally within the wastewater treatment device. The necessary reactions will not be impossible due to an excessively short hydraulic retention time, nor will excessively long hydraulic retention times lead to overgrowth or other abnormalities within the device. The temperature of the wastewater treatment device is 28-30°C, which is the suitable growth temperature for many microorganisms involved in wastewater treatment. For anaerobic ammonia-oxidizing bacteria, this temperature range is beneficial for maintaining their high enzyme activity. Sulfate-reducing bacteria and carbon-fixing bacteria also maintain good growth within this temperature range. Maintaining the temperature at 28-30°C makes the wastewater treatment process more stable. When the temperature is within this range, the growth and metabolism of microorganisms are relatively stable, and there will be no mass death or sharp decline in activity of microorganisms due to drastic temperature fluctuations.

[0027] According to an embodiment of the present invention, a wastewater treatment device includes an anaerobic ammonia oxidation reactor employing an upflow process. The inlet of the anaerobic ammonia oxidation reactor is located at the bottom, and the outlet is located at the top. The wastewater to be treated flows upwards within the reactor, providing relatively stable hydraulic conditions. Compared to other flow patterns, upflow reduces short-circuiting and dead zones, and also prevents sludge loss. Because the wastewater flows upwards, the sludge settles more easily at the bottom of the reactor under gravity. This helps maintain sufficient biomass within the reactor for both the anaerobic ammonia oxidation sludge and the anaerobic digestion sludge, thus ensuring efficient wastewater treatment. From the perspective of the substrate (pollutants in the wastewater), the bottom inlet allows pollutants such as ammonia nitrogen and sulfate in the wastewater to come into contact with microorganisms at the bottom of the reactor. From the perspective of the products, the upflow process facilitates the discharge of products such as nitrogen and hydrogen sulfide. The effluent outlet of the anammox reactor is connected to the effluent unit, and the effluent pipe is liquid-sealed below the liquid surface of the effluent unit, effectively preventing outside air (containing oxygen) from entering the anammox reactor. Simultaneously, this liquid-sealing method prevents harmful gases (such as hydrogen sulfide) generated within the anammox reactor from escaping into the surrounding environment. The liquid-sealing structure helps stabilize the hydraulic conditions of the anammox reactor and prevents short-circuit flow (the direct discharge of untreated wastewater).

[0028] According to embodiments of the present invention, the anammox reactor is equipped with a reflux pipe for recirculating the wastewater to be treated within the reactor. Further, the reflux ratio of the reflux pipe is 400%–600%. A higher reflux ratio allows for more contact between ammonia nitrogen in the wastewater and microorganisms. The recirculated wastewater contains various organic matter and sulfates, which can be further decomposed and transformed by microorganisms when they pass through the anammox reactor again. A higher reflux ratio helps stabilize the hydraulic conditions within the anammox reactor. Stable hydraulic conditions are crucial for microbial growth and reaction during wastewater treatment. The recirculated wastewater can buffer changes in influent flow rate and water quality, preventing hydraulic shocks within the anammox reactor. Simultaneously, through reflux, the microbial ecosystem within the anammox reactor can remain relatively stable. In some embodiments of the present invention, the anammox reactor employs a continuous flow process, which allows wastewater to continuously enter the reactor, ensuring the continuity of the treatment process. Compared to intermittent processes, there are no frequent start-up and shutdown phases, allowing microorganisms to remain in a relatively stable working state. For microorganisms, continuous flow processes provide a relatively stable growth environment. Microbial growth and metabolism are continuous processes, and continuous flow processes can maintain relative stability in environmental factors such as substrate (pollutants in wastewater) concentration, temperature, and redox potential. This stable environment is conducive to the acclimatization of microorganisms. During continuous flow, microorganisms can gradually adapt to changes in the composition and concentration of pollutants in the wastewater.

[0029] Figure 1 This is a schematic diagram of a wastewater treatment device in one embodiment of the present invention.

[0030] In some embodiments of the present invention, such as Figure 1 As shown, the wastewater treatment device includes:

[0031] Inlet unit 100 introduces the wastewater to be treated;

[0032] The anaerobic ammonia oxidation reactor 200 contains wastewater undergoing reactions such as denitrification and carbon fixation.

[0033] Wastewater discharged from the anaerobic ammonia oxidation reactor enters the effluent unit 300;

[0034] Gas collection unit 400: Gas discharged from the anaerobic ammonia oxidation reactor enters the gas collection unit 400.

[0035] The inlet pump 201 is used to pump the wastewater to be treated from the bottom inlet of the anaerobic ammonia oxidation reactor.

[0036] The reflux pump 202 connects the top reflux outlet and the bottom reflux inlet of the anaerobic ammonia oxidation reactor to promote mass transfer, contact and reaction between sludge and wastewater to be treated.

[0037] The anaerobic ammonia oxidation reactor 200 adopts an upflow process, with the inlet located at the bottom and the outlet located at the top. At the same time, the anaerobic ammonia oxidation reactor 200 has a return outlet and a return inlet at the top and bottom for returning the wastewater in the anaerobic ammonia oxidation reactor.

[0038] In some embodiments of the present invention, during the laboratory experiment phase, NH4 is introduced into the wastewater to be treated. + :HCO3 - The molar ratio is 1:1 to 1:2; the NH4 content of the wastewater to be treated + :SO4 2- The molar ratio is 2:1; the NH4 content of the wastewater to be treated + -N concentration is 100~400 mg / L.

[0039] The present invention will be further illustrated below through embodiments and related test experiments. In the following detailed description, numerous specific details are set forth for ease of explanation to provide a comprehensive understanding of the embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without these specific details. Moreover, the details in the following embodiments can be arbitrarily combined to form other feasible embodiments without conflict. All instruments, consumables, and reagents used in the following embodiments are commercially available unless otherwise specified.

[0040] Example 1

[0041] This embodiment 1 is passed through Figure 1 The wastewater treatment device shown denitrifies the wastewater.

[0042] The wastewater to be treated is pumped into the bottom of the anaerobic ammonia oxidation reactor using an inlet pump. The continuous flow anaerobic ammonia oxidation reactor is equipped with a reflux system, which returns the wastewater from the top of the reactor to the bottom via a reflux pump. The wastewater is then denitrified through a biological reaction, and the effluent enters the effluent tank through the effluent outlet.

[0043] The influent to the anaerobic ammonia oxidation reactor is distribution water, with an ammonia nitrogen concentration of 100-200 mg / L and NH4+ concentration of... + :HCO3 - The molar ratio is 1:2, the N / S molar ratio is 2:1, and no NO2 is added to the influent. - and NO3 -The influent is prepared using reagents such as ammonium sulfate, sodium bicarbonate, and sodium sulfate, and supplemented with necessary trace elements. The hydraulic retention time (HRT) of the anammox reactor is controlled at 2 days, and the temperature is controlled at 28–30℃. The influent undergoes nitrogen stripping pretreatment to maintain an anammox environment in the reactor, with dissolved oxygen (DO) controlled below 0.05 mg / L, oxidation-reduction potential (ORP) between -140 and -60 mV, and pH between 7.4 and 7.9. The reflux ratio of the anammox reactor is 500%. The inoculated sludge in the reactor is a mixture of traditional anammox sludge and anaerobic digestion sludge in a 1:1 mass ratio, with a sludge age of 30 days. After inoculation, the sludge concentration in the reactor is 6–7 g / L.

[0044] Figure 2 This is a graph showing the ammonia nitrogen test results in wastewater in Example 1 of the present invention; Figure 3 This is a graph showing the test results of nitrate nitrogen in wastewater in Example 1 of the present invention; Figure 4 This is a graph showing the test results of inorganic carbon in wastewater in Example 1 of the present invention.

[0045] like Figure 2 As shown, the anammox reactor reached equilibrium after 15 days, indicating that the start-up period of the anammox reaction is 6-12 days, and the ammonia nitrogen removal rate during the stable operation phase can reach 0.08-0.10 kgN / (m³). 3 •d) Ammonia nitrogen removal rate reaches 85-95%. For example... Figure 3 As shown, tests revealed that the effluent contained almost no NO3. - and NO2 - NO2 in the water - -N and NO3 - A -N concentration between 0.1-1 mg / L indicates that N2 is the main denitrification product. For example... Figure 4 As shown, the removal rate of inorganic carbon (IC) is 0.6~0.9 kgC / (m²). 3 •d). The molar ratio of ammonia nitrogen removal and inorganic carbon removal (ΔN / ΔC) in the influent and effluent was 1.0~1.3, proving that inorganic carbon is the electron acceptor in the denitrification reaction.

[0046] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A wastewater treatment method based on interspecies electron transport, comprising: The wastewater to be treated is fed into a wastewater treatment device, which includes ammonia-oxidizing bacteria, carbon-fixing bacteria, and sulfate-reducing bacteria. Under anaerobic conditions, in the wastewater treatment device, the ammonia-oxidizing bacteria use ammonia nitrogen in the wastewater to be treated as an electron donor for oxidation, the carbon-fixing bacteria use inorganic carbon in the wastewater to be treated as an electron acceptor for reduction, and the sulfate-reducing bacteria utilize the organic carbon released by the carbon-fixing bacteria and the sulfate in the wastewater to be treated for proliferation. At the same time, the sulfate-reducing bacteria exert interspecies electron transfer capabilities, enabling the oxidation and reduction reactions to occur synergistically. This achieves multi-species interaction among the ammonia-oxidizing bacteria, carbon-fixing bacteria, and sulfate-reducing bacteria, thereby denitrifying the wastewater to be treated through metabolic interactions among multiple bacterial species, resulting in treated wastewater.

2. The method according to claim 1, wherein, The sulfate-reducing bacteria exert interspecies electron transfer capabilities including: The sulfate-reducing bacteria receive electrons released by the oxidation reaction of the ammonia-oxidizing bacteria through their conductive flagella and cytochrome c, and then transfer these electrons to the carbon-fixing bacteria for reduction.

3. The method according to claim 1, wherein, The ammonia-oxidizing bacteria are introduced via anaerobic ammonia-oxidizing sludge. The sulfate-reducing bacteria are introduced from anaerobic digested sludge; The carbon-fixing bacteria are introduced together from the anaerobic ammonia oxidation sludge and the anaerobic digestion sludge.

4. The method according to claim 3, wherein, The mass ratio of anaerobic ammonia oxidation sludge to anaerobic digestion sludge in the wastewater treatment device is 1:

1. The total sludge concentration in the wastewater treatment device is 5~7g / L.

5. The method according to claim 1, wherein, The dissolved oxygen concentration in the wastewater treatment device is ≤0.05 mg / L; The oxidation-reduction potential in the wastewater treatment device is maintained at -140 to -60 mV.

6. The method according to claim 1, wherein, The hydraulic retention time of the wastewater treatment device is 1-2 days; The temperature of the wastewater treatment device is 28~30℃.

7. The method according to any one of claims 1-6, wherein, The wastewater treatment device includes an anaerobic ammonia oxidation reactor employing an upflow process. The inlet of the anaerobic ammonia oxidation reactor is located at the bottom of the reactor, and the outlet of the reactor is located at the top of the reactor.

8. The method according to claim 7, wherein, The anaerobic ammonia oxidation reactor is equipped with a reflux pipe for recirculating the wastewater to be treated within the reactor.

9. The method according to claim 8, wherein, The reflux ratio of the reflux pipe is 400% to 600%.

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