A method for reducing total nitrogen in nitrogen-containing wastewater to an ultra-low concentration

Abstract

The present application belongs to the technical field of nitrogen-containing wastewater biological treatment, and relates to a method for reducing total nitrogen in nitrogen-containing wastewater to an ultralow concentration. The method combines nitrification with Biotra-DN. The formed system does not need a sedimentation tank and a sludge discharge system, has a small footprint, low investment, can reduce TN in water, including but not limited to dredging water and / or water from a lake after being divided, aquaculture wastewater, industrial wastewater, municipal wastewater and river water, to below 1 mg / L, only needs simple backwashing, has a short residence time, is simple in daily operation and maintenance, and is low in operation cost.

Description

Technical Field

[0001] This invention belongs to the field of biological treatment technology for nitrogen-containing wastewater, specifically relating to a method for reducing the total nitrogen in nitrogen-containing wastewater to ultra-low concentrations. Background Technology

[0002] Water resources, especially freshwater resources usable by humans, are extremely scarce in today's world, where per capita resources are being depleted at an accelerating pace. This makes protecting limited freshwater resources and treating polluted water bodies even more important. Nitrogenous pollutants in wastewater mainly consist of organic nitrogen (proteins, urea, etc.) and ammonia nitrogen (NH4). + -N), nitrite nitrogen (NO2) - -N) and nitrate nitrogen (NO3) - Nitrogen exists in various forms, including nitrogen (NO3-), and is present in every corner of nature, playing a vital role in all aspects of the ecosystem. However, excessive nitrogen input can cause environmental pollution and harm the health of aquatic ecosystems. Too much nitrogen can lead to the proliferation of algae, causing algal blooms in rivers and lakes and red tides in the sea. This not only affects appearance but also consumes large amounts of dissolved oxygen in the water, leading to a decrease in dissolved oxygen concentration, mass mortality of aquatic organisms, and a decline in water quality, resulting in blackening and foul odors. Simultaneously, NO3- in the water... - -N and NO2 - Excessive levels of -N can also be harmful to humans and aquatic organisms.

[0003] To remove total nitrogen from water, physical, chemical, and biological methods are generally employed. Physical techniques primarily remove pollutants through physical means, such as removing bottom sludge, diluting with water, and mechanical algae removal. Sludge removal removes pollutants from the river system, significantly reducing the contribution of bottom sediment to the overlying water and thus improving water quality. Water diversion involves using hydraulic facilities such as sluice gates and pumping stations to introduce clean water from upstream or nearby sources to improve the water quality of downstream polluted rivers. Mechanical algae removal uses filters and screens to quickly remove surface algae. Physical methods are simple in equipment and operation, but expensive, and only address the symptoms, generally failing to meet discharge standards, and are mostly used as pretreatment or emergency measures.

[0004] Chemical methods involve adding appropriate chemical agents to react with pollutants in the water, generating gases or precipitates that are separated from the water, or degrading them into low-toxicity or non-toxic chemical forms, thereby removing pollutants from the water. Common methods include coagulation and sedimentation, adding chemical agents to kill algae, and adding lime for denitrification. For low-ammonia-nitrogen wastewater, adsorption, breakpoint chlorination, and ion exchange methods can also be used. Chemical methods offer the most immediate and noticeable results, but they are very prone to causing secondary pollution of water bodies, have high operating costs, and do not address the root cause. Chemical agents often need to be repeatedly added, resulting in high treatment costs. Long-term use can also lead to aquatic ecological imbalance, and these methods are generally used as supplementary or emergency control technologies.

[0005] It can be seen that physical and chemical methods are usually costly, only address the symptoms and not the root cause, and easily introduce other byproducts, causing secondary pollution to water bodies. Biotechnology mainly improves the self-regulation capacity of ecosystems, perfects system functions, realizes feedback regulation mechanisms, and coordinates external environmental pollution factors. Biotechnology utilizes specific organisms—plants, microorganisms, or protozoa—to absorb, transform, remove, or degrade environmental pollutants, achieving environmental purification and ecological restoration. It primarily focuses on in-situ remediation, resulting in thorough degradation, low cost, and compatibility with various other technologies. Due to its economic efficiency and the absence of secondary pollution, biological methods are environmentally friendly and sustainable, making them the mainstream process in wastewater denitrification.

[0006] Biotechnology includes natural ecological purification and microbial treatment. Natural ecological purification involves the purposeful introduction of superior aquatic plant species or the restoration of existing damaged plants, promoting the recovery of aquatic vegetation in degraded aquatic ecosystems and achieving a virtuous cycle in the aquatic ecosystem. It is suitable for water bodies with low pollution levels and is environmentally friendly. However, it is also suitable for water bodies with low pollution levels, has high specificity, a long removal time, requires a large area, and the subsequent harvesting and placement of plants need to be addressed.

[0007] Microbial treatment: Microbial agents can be directly added to water bodies for treatment, but this usually requires large dosages and repeated additions. Therefore, traditional activated sludge and biofilm methods are mainly used to colonize microorganisms and prevent loss. The activated sludge method is now widely used for treating various wastewaters. It utilizes suspended activated sludge in wastewater to adsorb and decompose organic matter or certain inorganic salts. The biofilm method is a new type of wastewater treatment technology that organically combines membrane filtration technology with the activated sludge method. It uses a membrane separation device to effectively retain activated sludge and large molecular organic matter in the biological reaction tank, increasing the sludge concentration and organic matter degradation rate, and improving the effluent quality. In recent years, due to researchers' continuous in-depth research and improvement of the biochemical reaction mechanism of microorganisms, many new processes have emerged, making the application range of this technology increasingly wide and significantly improving treatment efficiency. Microbial treatment can completely remove pollutants, has minimal environmental impact, short remediation time, low capital investment, simple in-situ remediation operation, low energy consumption, no secondary pollution, and can restore the self-purification capacity of water bodies.

[0008] Traditional biological denitrification processes include oxidation ditch, O / A, A / O, and A 2 O, SBR, MBR, etc., all rely on nitrification-denitrification. Nitrification requires aeration, which increases energy consumption, and denitrification requires the addition of carbon sources, which increases operating costs. They are ineffective in treating low C / N wastewater, have long retention times, require large land areas, produce large amounts of sludge, are complex to operate and manage, and it is difficult to achieve low concentrations in the effluent.

[0009] Novel nitrogen removal processes include simultaneous nitrification-denitrification, anaerobic ammonium oxidation (ANAO), short-cut nitrification-denitrification, heterotrophic nitrification-aerobic denitrification, semi-nitrification-ANAO, and autotrophic denitrification. Most of these new processes offer advantages such as energy and land saving, reduced carbon source input, and decreased carbon emissions and sludge production. However, simultaneous nitrification-denitrification is an integrated reaction with complex microbial communities, significant oxygen influence, and unstable operation. Anaerobic ammonium oxidation requires demanding cultivation conditions, necessitating a stable supply of NO2-N, and generally needs to be combined with other processes, such as incorporating partial nitrification processes at the upstream end of the system to ensure high nitrogen removal efficiency. Short-cut nitrification-denitrification requires suppression of NOB enrichment (AOB), which is difficult to control. Heterotrophic nitrification-aerobic denitrification has high requirements for carbon sources and aeration rates, increasing energy consumption and operating costs. Summary of the Invention

[0010] The purpose of this invention is to provide a method for reducing the total nitrogen in nitrogen-containing wastewater to ultra-low concentrations, addressing the problems existing in the prior art. This method combines nitrification with Biotra-DN, and the resulting system does not require sedimentation tanks or sludge removal systems, has a small footprint, low investment, and can reduce TN in wastewater to below 1 mg / L. It only requires simple backwashing, has a short retention time, simple daily operation and maintenance, and low operating costs.

[0011] Therefore, the present invention provides a method for reducing total nitrogen in wastewater to ultra-low concentrations, comprising:

[0012] Step A: In the reaction tank I of the nitrification system, the nitrification composite microbial preparation is mixed and cultured with carrier I and nitrogen-containing wastewater to obtain carrier I with a stable nitrification composite microbial film attached.

[0013] Step B involves directly feeding nitrogen-containing wastewater at full load into reaction tank I of the nitrification system to treat ammonia nitrogen degradation and obtain primary ammonia nitrogen-reduced wastewater.

[0014] Step C: In the reaction tank II of the Biotra-DN system, the Biotra-DN composite microbial preparation is mixed and cultured with carrier II and primary ammonia nitrogen reduction wastewater to obtain carrier II with stable attachment of Biotra-DN composite biofilm.

[0015] Step D: The primary ammonia nitrogen reduction wastewater is directly fed into the reaction tank II of the Biotra-DN system at full load for total nitrogen degradation treatment to obtain dischargeable water;

[0016] Among them, the ammonia nitrogen in the primary ammonia nitrogen reduction wastewater is <0.5 mg / L; and the total nitrogen in the dischargeable water is <1 mg / L.

[0017] According to some embodiments of the present invention, step A includes:

[0018] Step S1: Add the nitrifying compound microbial agent to reaction tank I containing carrier I, so that it is evenly distributed on carrier I, and add nitrogen-containing wastewater to reaction tank I, so that the water level rises to just submerge carrier I, to obtain a mixture of nitrifying compound microbial agent-carrier I-nitrogen-containing wastewater;

[0019] Step S2: Aeration. The mixture of nitrifying complex microbial preparation, carrier I, and nitrogen-containing wastewater is cultured to allow the nitrifying complex microbial community to stably attach to carrier I and form a biofilm. Carrier I with a stable nitrifying complex microbial biofilm is obtained. The liquid in reaction tank I is then drained.

[0020] According to other embodiments of the present invention, step C includes:

[0021] Step T1: Add Biotra-DN composite microbial agent to reaction tank II containing carrier II, so that it is evenly distributed on carrier II, and add primary ammonia nitrogen reducing wastewater to reaction tank II, so that the water level rises to just submerge carrier II, to obtain a mixture of Biotra-DN composite microbial agent-carrier II-primary ammonia nitrogen reducing wastewater.

[0022] Step T2: Bottom stirring or internal circulation is used to cultivate the mixture of Biotra-DN composite microbial preparation-carrier II-primary ammonia nitrogen reduction wastewater, so that the Biotra-DN composite microbial community can stably attach to carrier II to form a biofilm, and carrier II with a stable Biotra-DN composite microbial film is obtained. The liquid in reaction tank II is then drained.

[0023] Preferably, in steps S2 and T2, the water temperature is maintained between 18 and 30°C; preferably, the culture time is 3 to 5 days.

[0024] In this invention, the nitrifying compound microbial preparation includes nitrifying bacteria, biological aid I, and nutrient I.

[0025] Preferably, the nitrifying bacteria include Nitrosomonas and / or Nitrobacterium.

[0026] According to the present invention, the biological adjuvant I includes microcarrier I, growth factor I, and protective agent I.

[0027] In some embodiments of the present invention, the microcarrier I includes one or more of talc powder, pumice powder, zeolite powder, powdered activated carbon, bamboo charcoal powder, white carbon black, diatomaceous earth, polycaprolactone, and calcium alginate.

[0028] In some embodiments of the present invention, the growth-promoting factor I includes trace metal elements and / or vitamins.

[0029] In some embodiments of the present invention, the protective agent I includes one or more of glycerol, trehalose, nitrite and nitrate;

[0030] In some embodiments of the present invention, the nutrient agent I is a CNP-containing substance I, which includes one or more of glucose, urea, peptone and potassium dihydrogen phosphate;

[0031] Preferably, the ratio of nitrifying bacteria, biological aid I, and nutrient I in the nitrifying compound microbial preparation is 1-5:1-5:1-5.

[0032] According to the present invention, the Biotra-DN compound microbial preparation comprises denitrifying bacteria, biological adjuvant II, and nutrient II.

[0033] Preferably, the denitrifying bacteria include Pseudomonas and / or Bacillus;

[0034] According to the present invention, the biological adjuvant II includes microcarrier II, growth promoting factor II, and protective agent II.

[0035] In some embodiments of the present invention, the microcarrier II includes one or more of the following: activated carbon powder, powdered activated carbon, bamboo charcoal powder, white carbon black, diatomaceous earth, polycaprolactone, calcium alginate, cassava starch, and corn starch.

[0036] In some embodiments of the present invention, the growth factor II includes trace metal elements and / or vitamins.

[0037] In some embodiments of the present invention, the protective agent II comprises glycerol and / or trehalose;

[0038] In some embodiments of the present invention, the nutrient agent II is a CNP-containing substance II, which includes one or more of glucose, urea, peptone and potassium dihydrogen phosphate.

[0039] Preferably, the ratio of denitrifying bacteria, biological adjuvant II, and nutrient II in the Biotra-DN compound microbial preparation is 1-5:1-5:1-5.

[0040] According to the present invention, the nutrient I and the nutrient II may be the same or different; preferably, the mass ratio of carbon, nitrogen and phosphorus in the nutrient I and the nutrient II is 100:5:1.

[0041] In some embodiments of the present invention, the carrier I includes a bio-rope; preferably, the bio-rope is composed of PET nano-modified composite fibers, and more preferably, the bio-rope has a diameter of 80-85 mm, a specific surface area > 0.55 m² / g, a dry weight > 50 g / m, and a tensile strength > 2800 N.

[0042] In this invention, the carrier II comprises activated carbon and / or activated coke.

[0043] In some embodiments of the present invention, the activated carbon is coal-derived granular activated carbon; preferably, the activated carbon has an iodine value of 600–1100 mg / g, a strength >90%, and a specific surface area of ​​500–1200 m². 2 / g.

[0044] In some embodiments of the present invention, the activated carbon has an iodine value of 400-800 mg / g, a strength >90%, and a specific surface area of ​​400-800 m². 2 / g.

[0045] In some embodiments of the present invention, the nitrogen-containing wastewater includes one or more of the following: lake dredging water, lake water from dismantling enclosures, aquaculture wastewater, industrial wastewater, municipal wastewater, and river water.

[0046] This invention combines nitrification with Biotra-DN (coupled treatment). The nitrification system uses a carrier inoculated with self-developed nitrifying bacteria, primarily converting ammonia nitrogen to nitrite nitrogen, and then to nitrate nitrogen, under aerobic conditions. The Biotra-DN system uses specially screened activated carbon inoculated with self-developed denitrifying bacteria, which degrade nitrate nitrogen into nitrogen gas under anaerobic conditions using organic matter as a carbon source. The system formed by combining nitrification and Biotra-DN requires only one-time addition of both the bacteria and the carrier, eliminating the need for subsequent replenishment; only the nitrification system requires aeration. This coupled system can efficiently treat nitrogen-containing wastewater, achieving a total nitrogen (TN) concentration of <1 mg / L. It produces minimal sludge, eliminating the need for sedimentation tanks and sludge removal systems. The entire system has a small footprint, low investment, requires only simple backwashing, has a short head retention time (HRT), simple daily maintenance, low operating costs, and is environmentally friendly with no secondary pollution. Attached Figure Description

[0047] The invention will now be further described with reference to the accompanying drawings.

[0048] Figure 1 This is a schematic diagram of the nitrogen removal device for nitrogen-containing wastewater used in this invention.

[0049] Figures 2-8 The total nitrogen removal results of nitrogen-containing wastewater in Examples 1 to 7 are shown respectively. Detailed Implementation

[0050] To facilitate understanding of the present invention, it will be described in detail below with reference to embodiments. However, before describing the present invention in detail, it should be understood that the present invention is not limited to the specific embodiments described. It should also be understood that the terminology used herein is for describing specific embodiments only and is not intended to be restrictive.

[0051] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. While any methods and materials similar to or equivalent to those described herein may also be used in the practice or testing of this invention, preferred methods and materials are now described.

[0052] I. Terminology

[0053] The term "dischargeable water" as used in this invention refers to water that meets the Class III water discharge standard (GB 3838-2002) of the Surface Water Environmental Quality Discharge Standard.

[0054] The term "self-fermenting denitrifying bacteria" as used in this invention refers to microbial denitrifying bacteria strains selected from nature that can remove nitrate nitrogen from water. These strains are formulated with biological aids and nutrients in a professional ratio to form a self-fermenting denitrifying bacteria agent, which is mainly used to start up or improve the nitrate nitrogen removal capacity of wastewater treatment systems.

[0055] The term "Biotra-DN" used in this invention is a trademark of Shanghai Diyu Technology Co., Ltd., referring to the anoxic denitrification process within the "High-Efficiency Biological Activated Carbon Filter Process" Biotra. The Biotra process integrates "adsorption-concentration-online regeneration," utilizing a combination of highly effective microbial communities and specially selected biological activated carbon. This technology effectively removes recalcitrant pollutants such as COD, ammonia nitrogen, or total nitrogen from water, providing a green and environmentally friendly solution without secondary pollution. It is divided into aerobic and anoxic processes. Biotra-DN represents the anoxic denitrification process within this process.

[0056] The term "ultra-low concentration" as used in this invention refers to the reduction of total nitrogen (TN) in water to 1 mg / L.

[0057] The term "EBCT" (Empty Bed Contact Time) used in this invention refers to the time required for water to flow through the space occupied by the filter bed, assuming no filter bed is installed, and is measured in minutes.

[0058] The term "nitrogen-containing wastewater" as used in this invention refers to wastewater containing ammonia nitrogen and total nitrogen. It can be used interchangeably with "nitrogen-containing wastewater raw water" and includes, but is not limited to, one or more of the following: lake dredging water, lake water from dismantling enclosures, aquaculture wastewater, industrial wastewater, municipal wastewater, and river water.

[0059] In this invention, the terms "wastewater" and "sewage" can be used interchangeably.

[0060] The terms “about,” “approximately,” “substantially,” and “mainly” used herein, when combined with a range of elements, concentrations, temperatures, or other physical or chemical properties or characteristics, cover variations that may exist within the upper and / or lower limits of the range of the property or characteristic, including variations caused, for example, by rounding, measurement methods, or other statistical changes. For example, as used herein, “about” in relation to numerical values ​​such as quantity and weight is defined as all numerical values ​​for each specific value plus or minus 1%. For example, the term “about 10%” should be understood as “9% to 11%.”

[0061] II. Implementation Plan

[0062] As mentioned earlier, traditional biological denitrification processes are ineffective at treating nitrogen-containing wastewater, have long retention times, require large land areas, produce large amounts of sludge, are complex to operate and manage, and struggle to achieve low effluent concentrations. While most newer processes offer advantages such as energy and land savings, reduced carbon source dosage, and decreased carbon emissions and sludge production, simultaneous nitrification-denitrification in these processes is an integrated reaction with complex microbial communities, significant oxygen influence, and unstable operation. Anaerobic ammonia oxidation requires demanding cultivation conditions, necessitating a stable supply of NO2-N, and generally requires combination with other processes, such as incorporating partial nitrification at the upstream end of the process to ensure high denitrification efficiency. Short-cut nitrification-denitrification processes require suppression of NOB enrichment (AOB), which is difficult to control. Heterotrophic nitrification-aerobic denitrification has high requirements for carbon sources and aeration rates, increasing energy consumption and operating costs. Therefore, the inventors have conducted extensive and in-depth research on nitrogen-containing wastewater treatment technologies.

[0063] The inventors have discovered that combining nitrification with Biotra-DN (coupled) results in a nitrification system inoculated with self-fermenting nitrifying bacteria. This system primarily converts ammonia nitrogen into nitrite nitrogen, and then into nitrate nitrogen, under aerobic conditions. The Biotra-DN system, on the other hand, uses modified activated carbon inoculated with a self-developed denitrifying agent. Under anaerobic conditions, heterotrophic denitrifying bacteria using organic matter as a carbon source degrade nitrate nitrogen into nitrogen gas. In this system, both the agent and carrier are added only once, eliminating the need for subsequent replenishment. The nitrification system only requires aeration. Biotra-DN can treat nitrogen-containing wastewater to below 1 mg / L.

[0064] Therefore, the wastewater treatment system of the present invention is composed of a nitrification system 1 and a Biotra-DN system 2 coupled in series, as follows: Figure 1 As shown.

[0065] The nitrification system 1 consists of a raw water tank 11, a nitrification system inlet pump 12, a reaction tank I 13, and an intermediate water storage tank 21 connected in series. The raw water tank 11 is connected to the bottom inlet 131 of the reaction tank I via the nitrification system inlet pump 12. The top outlet 132 of the reaction tank I is connected to the intermediate water storage tank 21 via a pipe. An air inlet 133 is also provided at the bottom of the reaction tank I, which is connected to the nitrification system air pump 14.

[0066] The Biotra-DN system consists of an intermediate water storage tank 21, a Biotra-DN system inlet pump 22, a reaction tank II 23, and a product water tank 24 connected in series. The intermediate water storage tank 21 is connected to the bottom inlet I 231 of the reaction tank II via the Biotra-DN system inlet pump 22. The top outlet 232 of the reaction tank II is connected to the product water tank 24. The reaction tank II is also equipped with a carbon source dosing device 26, which is connected to the bottom inlet II 233 of the reaction tank II via a carbon source feed pump 25.

[0067] The reaction tank I13 of nitrification system 1 is connected to the reaction tank II23 of Biotra-DN system 2 via intermediate water storage tank 21 and Biotra-DN system inlet pump 22.

[0068] There are no particular restrictions on reaction tank I and reaction tank II in this invention. Conventional filters in the field can be used, as long as they can achieve the present invention. For example, the filter in Chinese patent CN 113185005 A can be used.

[0069] Accordingly, the method for removing total nitrogen from water according to the present invention includes the following steps:

[0070] (1) Add the nitrifying compound microbial preparation to the reaction tank I containing biological rope, so that it is evenly distributed on the carrier I, and add nitrogen-containing wastewater raw water to the reaction tank I, so that the water level rises to just submerge the carrier I, and obtain a mixture of nitrifying compound microbial preparation-carrier I-nitrogen-containing wastewater;

[0071] (2) Maintain the water temperature between 18 and 30°C, aerate, and culture the mixture of nitrifying compound microbial preparation-carrier I-nitrogenous wastewater for 3 to 5 days, so that the nitrifying compound microbial community can stably attach to carrier I to form a biofilm, obtain carrier I with a stable nitrifying compound microbial biofilm, and drain the liquid in reaction tank I.

[0072] (3) Nitrogen-containing wastewater is directly fed into the reaction tank I of the nitrification system at full load to degrade ammonia nitrogen and obtain primary ammonia nitrogen-reducing wastewater with ammonia nitrogen <0.5mg / L;

[0073] (4) Add Biotra-DN composite microbial agent to reaction tank II containing carrier II, so that it is evenly distributed on carrier II, and add primary ammonia nitrogen reduction wastewater to reaction tank II, so that the water level rises to just submerge carrier II, and obtain a mixture of Biotra-DN composite microbial agent-carrier II-primary ammonia nitrogen reduction wastewater.

[0074] (5) Bottom stirring or internal circulation is used to cultivate the mixture of Biotra-DN composite microbial preparation-carrier II-primary ammonia nitrogen reduction wastewater, so that the Biotra-DN composite microbial community can be stably attached to carrier II to form a biofilm, and carrier II with stable attachment of Biotra-DN composite microbial film is obtained. The liquid in reaction tank II is then drained.

[0075] (6) The primary ammonia nitrogen reduction wastewater is directly fed into the reaction tank II of the Biotra-DN system at full load for total nitrogen degradation treatment to obtain dischargeable water with total nitrogen <1mg / L.

[0076] In this invention, the nitrifying compound microbial preparation includes nitrifying bacteria, biological aid I, and nutrient I.

[0077] In this invention, the nitrifying bacteria are obtained by taking sludge from the aerobic tank of the wastewater treatment plant in Wujin Textile Industrial Park, Changzhou City, Jiangsu Province, adding it to water containing ammonia nitrogen, and culturing it under aeration for 5 days. The bacterial community analysis results show that it mainly includes Nitrosomonas and Nitrobacterium, and the ratio of Nitrosomonas to Nitrobacterium is 3:5 (quantity ratio). The water containing ammonia nitrogen is wastewater prepared from river water with an ammonia nitrogen concentration of 100 mg / L.

[0078] According to the present invention, the biological adjuvant I includes microcarrier I, growth factor I, and protective agent I.

[0079] In this invention, the microcarrier I is mainly used for bacteria that can attach biofilms, providing a place for bacterial growth and rapidly forming biofilms; preferably, the microcarrier I includes, but is not limited to, one or more of talc, pumice, zeolite, powdered activated carbon, bamboo charcoal powder, white carbon black, diatomaceous earth, polycaprolactone, and calcium alginate.

[0080] In this invention, the growth-promoting factor I can provide the trace components required for bacterial growth; preferably, the growth-promoting factor I includes one or more of all trace metal elements and / or one or more of all vitamins.

[0081] In this invention, the protective agent I can keep the bacteria in a dormant state, maintain a certain activity of the bacteria, prevent the bacteria from dying, and prolong the stability time of the bacterial agent; preferably, the protective agent I includes one or more of glycerol, trehalose, nitrite and nitrate.

[0082] In some embodiments of the present invention, the nutrient agent I is a CNP-containing substance I, which includes one or more of glucose, urea, peptone and potassium dihydrogen phosphate.

[0083] Preferably, the ratio of nitrifying bacteria, biological aid I, and nutrient I in the nitrifying compound microbial preparation is 1-5:1-5:1-5.

[0084] In some specific examples of the present invention, the nitrifying compound microbial preparation is composed of Nitrosomonas, Nitrobacterium, talc, pumice, zeolite, diatomaceous earth, glycerol, nitrite, nitrate, glucose, urea, potassium dihydrogen phosphate, and peptone; wherein, Nitrosomonas and Nitrobacterium are extracted from natural water, and the other biological aids and nutrients are all purchased from common markets.

[0085] In some specific preferred embodiments of the present invention, the nitrifying compound microbial preparation is composed of Nitrosomonas, Nitrobacterium, talc, pumice, zeolite, diatomaceous earth, glycerol, nitrite, nitrate, glucose, urea, potassium dihydrogen phosphate, and peptone in a ratio of 3:5:5:4:4:1:1:2:2:1:1:1:1.

[0086] According to the present invention, the Biotra-DN compound microbial preparation comprises denitrifying bacteria, biological adjuvant II, and nutrient agent II.

[0087] In this invention, the denitrifying bacteria consist of *Pseudomonas stearothermii* DY-2316 (culture preservation number GCMCC No. 28879) and *Bacillus licheniformis* DY-2306 (culture preservation number CGMCC No. 28526). Furthermore, the ratio of *Pseudomonas stearothermii* to *Bacillus licheniformis* is 5:5 (quantitative ratio).

[0088] According to the present invention, the biological adjuvant II includes microcarrier II, growth promoting factor II, and protective agent II.

[0089] In this invention, the microcarrier II is mainly used for bacteria that can attach biofilms, providing a place for bacterial growth and rapidly forming biofilms; preferably, the microcarrier II includes one or more of the following: activated carbon powder, bamboo charcoal powder, white carbon black, diatomaceous earth, polycaprolactone, calcium alginate, cassava starch, and corn starch.

[0090] In this invention, the growth-promoting factor II can provide the trace components required for bacterial growth; the growth-promoting factor II includes one or more of all trace metal elements and / or one or more of all vitamins.

[0091] In this invention, the protective agent II can keep the bacteria in a dormant state, maintain a certain activity of the bacteria, prevent the bacteria from dying, and prolong the stability time of the bacterial agent; preferably, the protective agent II includes glycerol and / or trehalose.

[0092] In some embodiments of the present invention, the nutrient agent II is a CNP-containing substance II, which includes one or more of glucose, urea, peptone and potassium dihydrogen phosphate.

[0093] Preferably, the ratio of denitrifying bacteria, biological adjuvant II, and nutrient II in the Biotra-DN compound microbial preparation is 1-5:1-5:1-5.

[0094] According to the present invention, the nutrient I and the nutrient II may be the same or different; preferably, the mass ratio of carbon, nitrogen and phosphorus in the nutrient I and the nutrient II is 100:20:1.

[0095] In some specific examples of the present invention, the Biotra-DN composite microbial preparation is composed of Pseudomonas, Bacillus, ferrous sulfate, powdered activated carbon, bamboo charcoal powder, diatomaceous earth, calcium alginate, glycerol, trehalose, glucose, urea, potassium dihydrogen phosphate, and peptone.

[0096] In some specific preferred embodiments of the present invention, the Biotra-DN composite microbial preparation is composed of Pseudomonas, Bacillus, ferrous sulfate, powdered activated carbon, bamboo charcoal powder, diatomaceous earth, calcium alginate, glycerol, trehalose, glucose, urea, potassium dihydrogen phosphate, and peptone in a ratio of 5:5:5:4:2:2:1:2:2:1:1:1:1.

[0097] In some embodiments of the present invention, the carrier added to the nitrifying composite microbial preparation includes, but is not limited to, bio-ropes. The bio-ropes are composed of PET nano-modified composite fibers. Preferably, the bio-ropes have a diameter of 80-85 mm and a specific surface area > 0.55 m². 2 / g, dry weight > 50g / m, tensile strength > 2800N.

[0098] In this invention, the activated carbon carrier includes, but is not limited to, activated carbon and / or activated coke.

[0099] In some embodiments of the present invention, the activated carbon is coal-derived granular activated carbon; preferably, the activated carbon has an iodine value of 600–1100 mg / g, a strength >90%, and a specific surface area of ​​500–1200 m². 2 / g.

[0100] In some embodiments of the present invention, the activated carbon has an iodine value of 400-800 mg / g, a strength >90%, and a specific surface area of ​​400-800 m². 2 / g.

[0101] In this invention, the wastewater has a COD of 7-220 mg / L, an alkalinity of 41.3-123.7, a total nitrogen of 3.6-80 mg / L, and an ammonia nitrogen of 1.43-17.3 mg / L.

[0102] In some embodiments of the present invention, the nitrogen-containing wastewater includes, but is not limited to, lake dredging water and / or lake water from dismantling enclosures, aquaculture water, etc.

[0103] Those skilled in the art should understand that in this invention, sodium acetate is a type of carbon source and is the main nutrient required for the Biotra-DN system to degrade total nitrogen during operation. It is also a necessary condition for the system to degrade total nitrogen (not unique to this system; other denitrification processes also require carbon sources). The nutrient agent (CNP) is added as a nutrient agent to allow the bacteria to grow and multiply in large quantities, since the system needs to stand for 3 to 5 days without water intake during startup.

[0104] III. Testing Methods

[0105] 1. Ammonia nitrogen detection experiment

[0106] The main instruments required include: UV-Vis spectrophotometer (DR3900, HACH).

[0107] The main operating steps include:

[0108] (1) Turn on the UV-Vis spectrophotometer (DR3900, HACH) and select program 380.

[0109] (2) Take two 1-inch Hash detector cuvettes.

[0110] (3) Add 10 mL of the matching deionized water (or completely nitrogen-free water instead of the matching deionized water) to one of the cuvettes as a blank, and add 10 mL of the sample to the other cuvette.

[0111] (4) Add mineral stabilizer to each of the two cuvettes and shake well.

[0112] (5) Add polyvinyl alcohol dispersant to each of the two cuvettes and shake well.

[0113] (6) Add 0.4 mL of the matching Nessler's reagent to each of the two cuvettes and shake well.

[0114] (7) Start the instrument timer and time the reaction for 1 minute.

[0115] (8) After timing is complete, wipe the blank cuvette clean and place it in the adapter. Press the "Zero" key to zero the instrument.

[0116] (9) Wipe the colorimetric tube containing the sample clean and place it in the adapter. Press the "Read" key to read the ammonia nitrogen content.

[0117] 2. Total nitrogen detection experiment

[0118] The required instruments mainly include: a digestion reactor (DRB200, HACH) and a UV-Vis spectrophotometer (DR3900, HACH).

[0119] The main operating steps include:

[0120] (1) Take a low-range total nitrogen digestion reagent tube (detection range is 0-25mg / L) and add a packet of total nitrogen persulfate reagent powder.

[0121] (2) Take one reagent tube and add 2 mL of the matching deionized water (or completely nitrogen-free water instead of the matching deionized water) as a blank, and add 2 mL of sample to the remaining reagent tubes respectively.

[0122] (3) Cover the reagent tube and shake it vigorously for at least 30 seconds to mix thoroughly.

[0123] (4) Turn on the DRB200 digester and heat to 105°C. Insert the reagent tube into the digester, close the lid, and heat for 30 minutes to digest. After the digestion time is up, immediately remove the tube from the digester and place it on a reagent tube cooling rack to cool to room temperature.

[0124] (5) Open the caps of the reagent tubes and add one packet of TNA (Total Nitrogen A) reagent powder to each tube. Close the caps and shake the reagent tubes up and down for 15 seconds. Start the instrument timer and start the reaction for 3 minutes.

[0125] (6) After the timing period ends, open the caps of the reagent tubes and add one packet of TNB (Total Nitrogen B) reagent powder to each tube. Close the caps and shake the reagent tubes up and down for 15 seconds. Start the instrument timer and start the reaction for 2 minutes.

[0126] (7) After the timing period ends, open both TNC (Total Nitrogen C) reagent tubes and add 2 mL of digestion solution to each TNC reagent tube. Cover the tubes and slowly invert them 10 times to mix thoroughly. Start the instrument timer and start the reaction for 5 minutes.

[0127] (8) After the timing period ends, turn on the DR3900 and select the TN LR program. Wipe the blank test tube clean and place it in the 16mm circular adapter. Press the "Zero" key to zero the instrument.

[0128] (9) Wipe the reagent tube containing the sample clean and place it into the 16mm circular adapter. Press the "Read" key to read the total nitrogen content.

[0129] Example

[0130] The present invention will be specifically described below through specific embodiments. Unless otherwise specified, the experimental methods described below are standard laboratory methods. Unless otherwise specified, the experimental materials described below are commercially available.

[0131] use Figure 1 The nitrogen removal device for nitrogenous wastewater shown first mixes a nitrifying composite microbial agent with a bio-rope carrier and the raw nitrogenous wastewater, then aerates and cultivates it to obtain a bio-rope carrier with a stable nitrifying composite microbial film attached. The liquid in reaction tank I is then drained. Next, a Biotra-DN composite microbial agent is mixed with an activated carbon carrier and primary ammonia-reducing wastewater and cultivated to obtain an activated carbon carrier with a stable Biotra-DN composite microbial film attached. Primary ammonia-reducing wastewater is then introduced at full load into reaction tank II of the Biotra-DN system for total nitrogen degradation. Finally, wastewater and a corresponding proportion of nutrient solution are introduced into the reaction tank to degrade the target pollutants, yielding dischargeable water.

[0132] Example 1:

[0133] (I) Wastewater Indicators

[0134] Currently, reducing non-point source pollution, intercepting point source pollution, and measures such as dredging and dismantling enclosures have become the main means of water environment management. Generally, the sludge removed from the lake will generate dredging water after compression. This water needs to be treated to meet the Class III water standard (TN≤1mg / L) before it can be discharged back into the original water body. The specific pollutant indicators of the dredging water of a certain lake are shown in Table 1 below. Among them, TN is the main pollutant that is difficult to meet the standard, making treatment difficult.

[0135] Table 1

[0136] Value (mg / L) 7 90.1 3.6 2 0.5 7.24

[0137] (II) Preparation of nitrifying complex microbial preparations and Biotra-DN complex microbial preparations

[0138] (1) Preparation of nitrifying compound microbial preparation (nitrifying bacteria, biological aid I, and nutrient I):

[0139] The nitrifying bacteria were obtained by taking sludge from the aerobic tank of the wastewater treatment plant in Wujin Textile Industrial Park, Changzhou City, Jiangsu Province, adding it to water containing ammonia nitrogen, and culturing it under aeration for 5 days. The bacterial community analysis results showed that it mainly included Nitrosomonas and Nitrobacterium, and the ratio of Nitrosomonas to Nitrobacterium was 3:5 (quantity ratio). The water containing ammonia nitrogen was prepared by diluting river water to a concentration of 100 mg / L.

[0140] Biological adjuvant I includes microcarrier I, growth factor I, and protective agent I;

[0141] The aforementioned microcarrier I is a mixed reagent consisting of talc powder, pumice powder, zeolite powder, and diatomaceous earth in a mass ratio of 5:4:4:1;

[0142] Growth promoter I is a mixed reagent containing trace metal elements (magnesium sulfate, ferrous sulfate, and zinc chloride in a mass ratio of 1:1:1); Protectant I is a mixed reagent containing glycerol, nitrite, and nitrate in a mass ratio of 1:2:2.

[0143] The above-mentioned nutrient agent I is substance I containing CNP, which is a mixed reagent composed of glucose, urea, peptone and potassium dihydrogen phosphate in a mass ratio of 8:1:1:1;

[0144] The ratio of nitrifying bacteria, biological aid I, and nutrient I in the above-mentioned nitrifying compound microbial preparation is 5:4:1.

[0145] (2) Preparation of Biotra-DN compound microbial preparation (denitrifying bacteria, biological adjuvant II and nutrient II):

[0146] The denitrifying bacteria consist of *Pseudomonas stearothermii* DY-2316 (strain preservation number GCMCC No. 28879) and *Bacillus licheniformis* DY-2306 (strain preservation number CGMCC No. 28526). Furthermore, the ratio of *Pseudomonas stearothermii* to *Bacillus licheniformis* is 5:5 (quantitative ratio).

[0147] Biological adjuvants II include microcarriers II, growth factors II, and protective agents II;

[0148] Microcarrier II is a mixed reagent composed of coumarin powder, powdered activated carbon, bamboo charcoal powder, diatomaceous earth, and calcium alginate in a mass ratio of 5:4:2:2:1; growth promoter II is a mixed reagent composed of trace metal elements (magnesium sulfate, ferrous sulfate, and zinc chloride in a mass ratio of 1:1:1); and protective agent II is a mixed reagent composed of glycerol and trehalose in a mass ratio of 1:1.

[0149] Nutrient II is a substance containing CNP, which is a mixed reagent composed of glucose, urea, peptone and potassium dihydrogen phosphate in a mass ratio of 8:1:1:1.

[0150] The ratio of denitrifying bacteria, biological adjuvant II, and nutrient II in the above-mentioned Biotra-DN compound microbial preparation is 5:3:1.

[0151] (III) Treatment of the lake water

[0152] (1) Based on the mass of the carrier, 1‰ of the nitrifying compound microbial preparation is added to the reaction tank I containing the biological rope carrier, so that it is evenly distributed on the biological rope and other carriers. Nitrogenous wastewater is added to the reaction tank I, so that the water level rises to just submerge the biological rope and other carriers, and a mixture of compound microbial preparation-biological rope and other carriers-nitrogenous wastewater is obtained.

[0153] (2) Maintain the water temperature between 18 and 30°C, aerate, and culture the mixture of microbial composite culture medium, biological rope and other carriers, and nitrogen-containing wastewater for 3 to 5 days, so that the nitrifying composite microbial community can be stably attached to the biological rope and other carriers to form a biofilm, obtain the biological rope and other carriers with a stable nitrifying composite microbial biofilm, and drain the liquid in reaction tank I.

[0154] (3) Nitrogen-containing wastewater is directly fed into the reaction tank I of the nitrification system at full load to degrade ammonia nitrogen and obtain primary ammonia nitrogen-reducing wastewater with ammonia nitrogen <0.5mg / L;

[0155] (4) Based on the carrier mass, add 1% of Biotra-DN composite microbial preparation to reaction tank II containing activated carbon carrier, so that it is evenly distributed on the activated carbon carrier, and add primary ammonia nitrogen reduction wastewater to reaction tank II, so that the water level rises to just submerge the activated carbon carrier, and obtain a mixture of composite microbial preparation-activated carbon carrier-primary ammonia nitrogen reduction wastewater.

[0156] (5) Stir at the bottom or circulate internally to cultivate the mixture of compound microbial preparation-activated carbon carrier II-primary ammonia nitrogen reduction wastewater, so that the Biotra-DN compound microbial community can be stably attached to the activated carbon carrier to form a biofilm, obtain the activated carbon carrier with stable Biotra-DN compound microbial film attached, and drain the liquid in reaction tank II.

[0157] (6) The primary ammonia nitrogen reduction wastewater is directly fed into the reaction tank II of the Biotra-DN system at full load for total nitrogen degradation treatment to obtain dischargeable water with total nitrogen <1mg / L.

[0158] (iv) Operating parameters

[0159] The nitrification system is aerated to ensure dissolved oxygen levels are above 4 mg / L, with an EBCT of 30 min. The Biotra-DN system uses activated carbon A as the carrier and adds sodium acetate to provide a carbon source, with an EBCT of 4 h.

[0160] (V) Operational Data

[0161] Running data such as Figure 2 And as shown in Table 2 below:

[0162] Table 2

[0163] TN 3.38±0.53 0.97±0.49 72.21±9.91

[0164] From the above and Figure 2As shown in Table 2, the raw water requiring total nitrogen (including ammonia nitrogen and nitrate nitrogen) removal is pumped into the nitrification system via the nitrification system inlet pump. The nitrification system is filled with bio-strings inoculated with nitrifying bacteria, which convert ammonia nitrogen to nitrate nitrogen under aerobic conditions. Currently, ammonia nitrogen can be reduced to below 0.5 mg / L under sufficient alkalinity conditions. If the raw water alkalinity is insufficient or the pH is acidic, alkalinity or pH monitoring devices can be added for real-time adjustment. Oxygen is supplied by an air pump. The product water from the nitrification system is pumped into the reactor via the Biotra-DN system inlet pump. A carbon source needs to be added to convert nitrate nitrogen into nitrogen gas and water, thereby removing total nitrogen. This process will increase the pH, so the pH of the influent needs to be controlled to prevent it from becoming too high; acid can be added for adjustment if necessary. Through the combined action of the two systems, the total nitrogen in the product water can be controlled below 1 mg / L, at least meeting the total nitrogen and ammonia nitrogen requirements of Class III water in the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0165] Example 2:

[0166] To further illustrate the effectiveness of this invention, flotation water from a dredged lake was selected. The influent pollutant indicators are shown in Table 3 below. Using this invention, the process parameters were adjusted, and sodium acetate was added to the Biotra-DN system to provide a carbon source. EBCT = 3h, and the system was run continuously for approximately 15 days. The total nitrogen (TN) of the influent and effluent was then measured, and the results are as follows: Figure 3 As shown, for the first 6 days, the effluent concentration was between 1 and 1.5 mg / L, after which the total nitrogen (TN) in the effluent stabilized at <1 mg / L. This meets at least the total nitrogen and ammonia nitrogen requirements for Class III water in the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0167] Table 3

[0168] Value (mg / L) 16 105 5.6 4.1 7.85

[0169] Example 3:

[0170] To further illustrate the effectiveness of this invention, flotation water from a dredged lake was selected. The influent pollutant indicators are shown in Table 4 below. The invention was used to operate and adjust process parameters. Sodium acetate was added to the Biotra-DN system to provide a carbon source, and activated carbon C was used as a carrier. EBCT = 2h, and the system was run continuously for 2 months. The total nitrogen (TN) of the influent and effluent was measured, and the results are as follows: Figure 4 As shown, for the first 10 days or so, the total nitrogen (TN) in the effluent was between 1 and 2 mg / L. After that, the TN in the effluent fluctuated around 1 mg / L until it finally stabilized below 1 mg / L. This at least meets the total nitrogen and ammonia nitrogen requirements for Class III water in the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0171] Table 4

[0172] Value (mg / L) 27±4.08 117±7.53 4.65±1.40 2.75±1.34 0.53±0.25 0.07±0.03

[0173] Example 4:

[0174] To further illustrate the effectiveness of this invention, filtration water from dredged sediment of a lake was selected. The pollutant indicators of the influent are shown in Table 5 below. The process parameters were adjusted using this invention, with the Biotra-DN system employing two different activated carbon carriers in series, EBCT = 1h + 1h, and continuous operation for 20 days. The total nitrogen (TN) of the influent and effluent was measured, and the results are as follows: Figure 5 As shown, the total nitrogen (TN) in the system effluent is consistently <1 mg / L. This meets at least the total nitrogen and ammonia nitrogen requirements for Class III water in the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0175] Table 5

[0176] Value (mg / L) 10 46.3 7.0 6.48 8.23

[0177] Example 5:

[0178] To further illustrate the effectiveness of this invention, filtration water from dredged sediment of a lake was selected. The pollutant indicators of the influent are shown in Table 6 below. The process parameters were adjusted using this invention, with the Biotra-DN system employing two different activated carbon carriers in series. EBCT = 40 min + 40 min was used, and the system was run continuously for one week. The total nitrogen (TN) of the influent and effluent was then measured, and the results are as follows: Figure 6 As shown, the total nitrogen (TN) in the system effluent is consistently <1 mg / L. This meets at least the total nitrogen and ammonia nitrogen requirements for Class III water in the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0179] Table 6

[0180] Value (mg / L) 10±0 41.3±7.07 11.05±5.73 10.24±5.32 7.85±0.54

[0181] Example 6:

[0182] To further illustrate the effectiveness of this invention, filtration water from dredged sediment of a lake was selected. The pollutant indicators of the influent are shown in Table 7 below. The process parameters were adjusted using this invention, with the Biotra-DN system employing a two-stage EBCT (30 min + 30 min) connection, running continuously for 56 days. Total nitrogen (TN) in both the influent and effluent was measured, and the results are as follows: Figure 7 As shown, the total nitrogen (TN) in the system effluent is consistently <1 mg / L. This meets at least the total nitrogen and ammonia nitrogen requirements for Class III water in the "Surface Water Environmental Quality Standard" (GB 3838-2002).

[0183] Table 7

[0184] Value (mg / L) 17.67±5.13 60.0±15.8 14.13±4.37 13.25±4.18 7.70±0.62

[0185] Example 7:

[0186] To more specifically illustrate the effectiveness of this invention, a certain aquaculture wastewater was selected, with influent pollutant indicators as shown in Table 8 below. The requirement was that the effluent TN < 5 mg / L. The invention was used to operate and adjust the process parameters, where the EBCT of the nitrification system was 4 h, the EBCT of the denitrification system was 6 h, and the EBCT of the Biotra-DN system was 30 min. The TN of the influent and effluent was measured, and the results are as follows: Figure 8 As shown, the final effluent TN of the system is <1 mg / L, meeting the effluent quality standards.

[0187] Table 8

[0188] Value (mg / L) 220 80 4.65 56 7.49 16

[0189] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for reducing total nitrogen in nitrogen-containing wastewater to ultra-low concentrations, comprising: Step A: In the reaction tank I of the nitrification system, the nitrification composite microbial preparation is mixed and cultured with carrier I and nitrogen-containing wastewater to obtain carrier I with a stable nitrification composite microbial film attached. Step B involves directly feeding nitrogen-containing wastewater at full load into reaction tank I of the nitrification system to treat ammonia nitrogen degradation and obtain primary ammonia nitrogen-reduced wastewater. Step C: In the reaction tank II of the Biotra-DN system, the Biotra-DN composite microbial preparation is mixed and cultured with carrier II and primary ammonia nitrogen reduction wastewater to obtain carrier II with stable attachment of Biotra-DN composite biofilm. Step D: The primary ammonia nitrogen reduction wastewater is directly fed into the reaction tank II of the Biotra-DN system at full load for total nitrogen degradation treatment to obtain dischargeable water; Among them, the ammonia nitrogen in the primary ammonia nitrogen reduction wastewater is <0.5 mg / L; and the total nitrogen in the dischargeable water is <1 mg / L. Step S1: Add the nitrifying compound microbial agent to reaction tank I containing carrier I, so that it is evenly distributed on carrier I, and add nitrogen-containing wastewater to reaction tank I, so that the water level rises to just submerge carrier I, to obtain a mixture of nitrifying compound microbial agent-carrier I-nitrogen-containing wastewater; Step S2: Aeration. The mixture of nitrifying complex microbial preparation, carrier I, and nitrogen-containing wastewater is cultured to allow the nitrifying complex microbial community to stably attach to carrier I and form a biofilm. Carrier I with a stable nitrifying complex microbial biofilm is obtained. The liquid in reaction tank I is then drained. Step T1: Add Biotra-DN composite microbial agent to reaction tank II containing carrier II, so that it is evenly distributed on carrier II, and add primary ammonia nitrogen reducing wastewater to reaction tank II, so that the water level rises to just submerge carrier II, to obtain a mixture of Biotra-DN composite microbial agent-carrier II-primary ammonia nitrogen reducing wastewater. Step T2: Bottom stirring or internal circulation is used to cultivate the mixture of Biotra-DN composite microbial preparation-carrier II-primary ammonia nitrogen reduction wastewater, so that the Biotra-DN composite microbial community can stably attach to carrier II to form a biofilm, and carrier II with stable attachment of Biotra-DN composite microbial film is obtained. The liquid in reaction tank II is then drained. The nitrifying compound microbial preparation includes nitrifying bacteria, biological aid I, and nutrient I; the nitrifying bacteria include Nitrosomonas and Nitrobacterium; the ratio of Nitrosomonas to Nitrobacterium is 3:

5. The Biotra-DN compound microbial preparation includes denitrifying bacteria, biological aid II, and nutrient agent II; the denitrifying bacteria include Pseudomonas and Bacillus. The carrier I is a bio-rope; the bio-rope is composed of PET nano-modified composite fibers, and has a diameter of 80-85 mm and a specific surface area > 0.55 m². 2 / g, dry weight > 50g / m, tensile strength > 2800N; The carrier II is activated carbon and / or activated coke; the activated carbon is coal-derived granular activated carbon; the iodine value of the activated carbon is 600–1100 mg / g, the strength is >90%, and the specific surface area is 500–1200 m². 2 / g; and / or, the activated char has an iodine value of 400–800 mg / g, a strength >90%, and a specific surface area of ​​400–800 m² / g. 2 / g; The wastewater contained COD of 7-220 mg / L, alkalinity of 41.3-123.7, total nitrogen of 3.6-80 mg / L, and ammonia nitrogen of 1.43-17.3 mg / L.

2. The method according to claim 1, characterized in that, In steps S2 and T2, the water temperature is maintained between 18 and 30°C; the culture time is 3 to 5 days.

3. The method according to claim 1, characterized in that, The biological adjuvant I comprises microcarrier I, growth factor I, and protective agent I; the microcarrier I comprises one or more of talc, pumice, zeolite, powdered activated carbon, bamboo charcoal, silica, diatomaceous earth, polycaprolactone, and calcium alginate; and / or, the growth factor I comprises trace metal elements and / or vitamins; and / or, the protective agent I comprises one or more of glycerol, trehalose, nitrite, and nitrate. The nutrient I is a CNP-containing substance I, which includes one or more of glucose, urea, peptone, and potassium dihydrogen phosphate.

4. The method according to claim 3, characterized in that, The ratio of nitrifying bacteria, biological aid I, and nutrient I in the nitrifying compound microbial preparation is 1-5:1-5:1-5.

5. The method according to claim 1, characterized in that, The biological adjuvant II includes microcarrier II, growth factor II, and protectant II; the microcarrier II includes one or more of the following: ferrous sulfate, powdered activated carbon, bamboo charcoal powder, white carbon black, diatomaceous earth, polycaprolactone, calcium alginate, cassava starch, and corn starch; and / or, the growth factor II includes trace metal elements and / or vitamins; and / or, the protectant II includes glycerol and / or trehalose. The nutrient II is a CNP-containing substance II, which includes one or more of glucose, urea, peptone, and potassium dihydrogen phosphate.

6. The method according to claim 5, characterized in that, The ratio of denitrifying bacteria, biological adjuvant II, and nutrient II in the Biotra-DN compound microbial preparation is 1-5:1-5:1-5.

7. The method according to any one of claims 1-6, characterized in that, The nutrient I and nutrient II may be the same or different; the mass ratio of carbon, nitrogen and phosphorus in the nutrient I and nutrient II is 100:5:

1.

8. The method according to any one of claims 1-6, characterized in that, The nitrogen-containing wastewater includes one or more of the following: lake dredging water, lake water from dismantling enclosures, aquaculture wastewater, industrial wastewater, municipal wastewater, and river water.

Images