UBF reactor, deep denitrification system and deep denitrification method

Abstract

The invention provides a UBF reactor, a deep denitrification system and a deep denitrification method, the reactor comprises an anaerobic ammonia oxidation hot zone, a coupling zone and a deep denitrification guarantee zone from bottom to top, the coupling zone is provided with a first sulfur source dosing port, the deep denitrification guarantee zone is provided with a second sulfur source filler zone, and the outer layer of the UBF reactor is coated with a thermal insulation layer. By constructing a three-level function cooperation system, the problems that in the prior art, anaerobic ammonia oxidation nitrate nitrogen is left in an anaerobic ammonia oxidation hot area, sulfur source utilization is unstable, and the system is prone to being inhibited are solved, cooperation of deep nitrogen removal, stable operation and cost saving is achieved, and the method is suitable for high-nitrogen-content wastewater treatment.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and specifically relates to a UBF reactor, a deep denitrification system and method thereof. Background Technology

[0002] With the accelerated pace of industrial development and urbanization, environmental problems such as eutrophication caused by nitrogen-containing wastewater discharge are becoming increasingly severe, making the research and development of efficient nitrogen removal technologies increasingly urgent. Current biological nitrogen removal technologies have many limitations: traditional nitrification-denitrification processes have high energy consumption and operating costs; short-cut nitrification-denitrification processes have complex control conditions and poor stability; anaerobic ammonia oxidation processes require combination with other processes and face technical challenges such as residual nitrate nitrogen and unstable sulfur source utilization. Specifically, while the Anammox process alone can achieve autotrophic biological nitrogen removal, it theoretically produces 11% NO3. - For high ammonia nitrogen wastewater, the effluent cannot be directly discharged due to nitrate nitrogen limitations, requiring further denitrification to remove nitrate nitrogen. However, when sulfur-containing minerals are used as sulfur sources, their limited direct contact with microorganisms and reliance on surface reactions and diffusion mass transfer result in low mass transfer efficiency, affecting overall nitrogen removal efficiency and requiring a long hydraulic retention time (HRT). Furthermore, when readily available sulfur sources such as sodium thiosulfate are used as the primary electron donor, incompletely oxidized sulfur... 2- In particular, H2S can damage cytochrome enzymes, interfere with the energy metabolism of the microbial community, and inhibit the activity of other functional microbial communities. Coupled with Anammox, it can lead to poisoning of the AnAOB microbial community, system instability, or even collapse. Furthermore, the sulfur autotrophic denitrification process produces acid and consumes alkalinity, which can easily cause system acidification and lead to metabolic disorders of the microbial community. Buffers need to be added to adjust the alkalinity.

[0003] For example, the technical solution with patent number CN107162184A discloses a UBF reactor and its system and denitrification method that utilizes anaerobic ammonia oxidation-sulfur autotrophic denitrification coupled for nitrogen removal. Although this process integrates three autotrophic denitrification processes and attempts to achieve autotrophic denitrification driven by ammonia nitrogen, it suffers from drawbacks such as insufficient long-term effectiveness of the sulfur source and limited deep denitrification capacity: the denitrification effect of minerals as a slow-release sulfur source decreases with operating time, requiring frequent replacement to maintain efficiency in long-term operation, making it difficult to guarantee the continuity of high ammonia nitrogen wastewater treatment; moreover, its sulfur autotrophic denitrification stage has limited removal depth of nitrate nitrogen, and the total nitrogen in the effluent still requires a subsequent treatment unit, leading to an increase in overall cost.

[0004] For example, the technical solution with patent number CN115231700A discloses a method for simultaneous nitrogen and phosphorus removal from low C / N wastewater based on a coupled system of sulfur autotrophic denitrification and sulfate reduction. This process utilizes pyrrhotite to achieve sulfur autotrophic denitrification and iron ion removal. Although it constructs a sulfate reduction cycle, it suffers from problems such as narrow substrate compatibility, low treatment efficiency, and difficulty in stability control: First, the reaction substrate is only suitable for nitrate nitrogen, which cannot meet the denitrification requirements of high ammonia nitrogen wastewater, limiting its applicability; second, the slow sulfur release rate of pyrrhotite leads to a prolonged hydraulic retention time, hindering efficient wastewater treatment; third, the large-scale generation of sulfides during the reaction exacerbates alkalinity consumption, requiring continuous addition of alkali to maintain system stability, increasing operating costs and making long-term reliability difficult to guarantee.

[0005] Therefore, developing a technical solution that can achieve deep denitrification, stable operation, efficient utilization of sulfur source, and no need for additional alkalinity adjustment has become the key to solving the problem of nitrogen-containing wastewater treatment. Summary of the Invention

[0006] To address the problems mentioned in the background art, this application provides a UBF reactor, a deep denitrification system, and a method thereof.

[0007] According to a first aspect of the present invention, a UBF reactor is provided, which includes, from bottom to top, an anaerobic ammonia oxidation thermal zone, a coupling zone, and a deep denitrification protection zone. The coupling zone is provided with a first sulfur source dosing port, the deep denitrification protection zone is provided with a second sulfur source packing zone, and the outer layer of the UBF reactor is covered with an insulation layer.

[0008] In the above technical solution, the synergistic function of anaerobic ammonia oxidation and sulfur autotrophic denitrification is achieved through vertical partitioning design, and different forms of nitrogen are treated in a stratified manner to improve nitrogen removal efficiency; the heat insulation layer ensures stable temperature inside the reactor, adapts to the optimal metabolic environment of functional bacteria (anaerobic ammonia oxidizing bacteria and sulfur autotrophic denitrifying bacteria), and reduces the interference of temperature fluctuations on the reaction.

[0009] Furthermore, the primary sulfur source is thiosulfate, and its addition amount is based solely on the average effluent NO3 during the anaerobic ammonia oxidation period. - The concentration of nitrogen (N) determines the optimal sulfur content, and the S / N mass ratio must be ≥2.86 according to the reaction equation. Preferably, sodium thiosulfate is used. As a highly efficient soluble sulfur source, thiosulfate can precisely match the nitrate nitrogen load. By controlling the S / N ratio, it ensures the electron donor requirements of sulfur-autotrophic denitrifying bacteria while avoiding secondary pollution caused by excessive sulfur source. Dynamic adjustment of the dosage based on historical effluent data enables precise sulfur source addition, improving process economy and denitrification stability.

[0010] Furthermore, the second sulfur source is iron sulfide minerals, and the volume of iron sulfide mineral packing accounts for 20-30% of the total reaction zone volume of the UBF reactor. As a slow-release sulfur source, iron sulfide minerals form a dual sulfur source system with the first sulfur source, which is characterized by "rapid replenishment + long-term slow release," thus avoiding metabolic interruption caused by a single sulfur source. The packing ratio can be flexibly adjusted according to the nitrogen load, ensuring sufficient sulfur source while avoiding flow obstruction caused by over-packing, thereby balancing denitrification efficiency and hydraulic conditions.

[0011] Furthermore, the iron sulfide mineral is pyrite, preferably with a particle size of 2-5 mm and a crystal form of (111). The (111) crystal form of pyrite has high reactivity and can significantly improve the rate of sulfur autotrophic denitrification; the 2-5 mm particle size forms a gradient filter layer, which can both retain functional bacteria (anaerobic ammonia oxidizing bacteria and sulfur autotrophic denitrifying bacteria) and ensure water flow, realizing the three-in-one function of "physical interception + sulfur source supply + metabolic acceleration", and strengthening the system stability.

[0012] Furthermore, the UBF reactor is equipped with a three-phase separator at the top and a support zone at the bottom, with a glass bead structure within the support zone for support. The three-phase separator efficiently separates gas (N2), liquid (treated water), and solid (sludge), preventing sludge from being carried away by the gas. The glass bead structure in the support zone supports the upper packing material and microbial community, preventing reactor blockage and providing uniform water distribution for the influent, ensuring stable flow.

[0013] The second aspect of the present invention proposes a deep denitrification system, including the UBF reactor described in the first aspect, as well as a dosing device, an inlet device, and a dosing device connected to a first sulfur source dosing port, wherein the inlet device is connected to the bottom of the UBF reactor.

[0014] In the above technical solution, the integrated system design enables precise addition of sulfur source, stable delivery of influent and constant temperature control, ensuring the coordinated function of each zone of the UBF reactor.

[0015] Furthermore, the system also includes a gas flow meter and a temperature probe. The gas flow meter is located at the top of the three-phase separator in the UBF reactor, and the temperature probe penetrates the insulation layer and extends into the UBF reactor. The gas flow meter monitors nitrogen production in real time, indirectly reflecting the intensity of the denitrification reaction; the temperature probe accurately provides feedback on the temperature inside the reactor, preventing a decrease in bacterial activity due to temperature deviations and improving the controllability of system operation.

[0016] Furthermore, the dosing device includes a first sulfur source dosing tank and a first peristaltic pump. The first sulfur source dosing tank is connected to the first sulfur source dosing port via the first peristaltic pump. The peristaltic pump precisely controls the dosage of the first sulfur source. Combined with the S / N ratio design, it achieves metering matching between the sulfur source and nitrate nitrogen, avoiding incomplete denitrification due to insufficient sulfur source or secondary pollution due to excessive sulfur source, thus improving the efficiency of reagent utilization.

[0017] The third aspect of this invention proposes a deep denitrification method, implemented using the deep denitrification system described in the second aspect, the method comprising: S1. Start the UBF reactor, maintain the water temperature in the reaction zone of the UBF reactor at 30-37℃, inoculate anaerobic ammonia oxidation bacteria in the anaerobic ammonia oxidation hot zone, introduce the first sulfur source into the coupling zone to enrich sulfur autotrophic denitrifying bacteria, and fill the deep denitrification guarantee zone with the second sulfur source. S2. Nitrogenous wastewater is pumped into the UBF reactor through an inlet device, so that the water flows through the anaerobic ammonia oxidation thermal zone, coupling zone and deep denitrification guarantee zone in sequence, and the hydraulic retention time is controlled to be 1.8-3.6 h and the nitrogen load is 2-2.25 g N / L / d.

[0018] In the above technical solution, step-by-step start-up and parameter optimization enable rapid enrichment and functional stability of the bacterial community; temperature control ensures bacterial activity; and hydraulic condition design balances reaction time and treatment efficiency, enabling the system to operate stably for a long time with total nitrogen in the effluent ≤5 mg / L.

[0019] Furthermore, step S2 includes: Anaerobic ammonia oxidation occurs in the anaerobic ammonia oxidation hot zone, producing NH4+. + -N and NO2 - -N is converted to N2, while some NO3 is produced. - -N; Sulfate-autotrophic denitrifying bacteria in the coupling zone utilize the primary sulfur source to oxidize NO3 produced in the thermal zone using anaerobic ammonia. - -N is partially denitrified into NO2. - -N, NO2 - -N and NH4 that has not reacted with the anaerobic ammonium oxidation hot zone + -N is further converted to N2 through anaerobic ammonium oxidation; and some NO3 is also converted to N2. - -N is directly converted to N2 through complete denitrification; In the deep denitrification protection zone, sulfur-autotrophic denitrifying bacteria utilize the second sulfur source and the remaining first sulfur source to denitrify the NO3 remaining in the coupling zone. - -N is further denitrified into N2, achieving deep nitrogen removal; Among them, the NH4 in the nitrogen-containing wastewater in the influent device + -N: NO2 - -N is (1-1.1):1.

[0020] In the above technical solution, the three-stage relay denitrification mechanism (anaerobic ammonia oxidation as the main denitrification → sulfur autotrophic denitrification coupled with supplementary denitrification → pyrite-enhanced deep denitrification) achieves the removal of nitrogen in all forms; the nitrate nitrogen is converted step by step to avoid the accumulation of intermediate products, and the final effluent total nitrogen is ≤5 mg / L, achieving the goal of deep denitrification; at the same time, the alkalinity self-balancing (anaerobic ammonia oxidation to produce alkali → sulfur autotrophic denitrification to consume alkali) makes the effluent pH close to neutral, without the need for additional adjustment, reducing operating costs.

[0021] Compared with the prior art, the beneficial results of the present invention are as follows: (1) The present invention forms an anaerobic ammonia oxidation hot zone, a coupling zone and a deep denitrification guarantee zone by longitudinal partitioning. For the nitrate nitrogen naturally produced by Anammox process, a complete nitrogen conversion chain is constructed: "anaerobic ammonia oxidation main denitrification → sodium thiosulfate driven partial denitrification feed + full denitrification → pyrite enhanced deep denitrification". This solves the technical bottleneck of incomplete removal of nitrate nitrogen by traditional single process and achieves step-by-step precise removal of nitrogen forms.

[0022] (2) The pyrite in the deep denitrification protection zone of this invention forms a gradient filter layer through 2-5 mm particles, which efficiently intercepts anaerobic ammonia oxidizing bacteria and sulfur autotrophic denitrifying bacteria, and constructs a stable microbial ecological niche; its (111) crystal form acts as a "metabolic accelerator", which significantly improves the anaerobic ammonia oxidation activity and sulfur autotrophic denitrification activity, solves the problem of mismatched proliferation rate of functional bacteria and easy loss, and strengthens the metabolic intensity and shock resistance of the system.

[0023] (3) This invention forms an alkalinity self-balancing mechanism by dynamically coupling Anammox alkali production with sulfur autotrophic denitrification alkali consumption, so that the pH of the effluent is stable at 7.05±0.11, without the need for additional acid or alkali addition; the total nitrogen removal rate of the system is as high as 97.99%, and the total nitrogen in the effluent is stable at 4.3±2.8 mg / L, breaking through the denitrification bottleneck of traditional processes and achieving near-limit denitrification effect.

[0024] (4) The present invention adopts a single-stage UBF reactor to integrate three functional areas, avoiding the increase in space and equipment costs caused by multiple reactors in series, and realizing engineering intensification; using tailings pyrite as a self-sustaining sulfur source to replace the continuous addition of traditional chemical sulfur sources, it not only reduces the cost of reagent consumption, but also promotes the resource utilization of solid waste, taking into account both technological innovation and environmental sustainability. Attached Figure Description

[0025] The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the invention. Other embodiments and many anticipated advantages of the embodiments will be readily recognized as they become better understood through reference to the following detailed description. Elements in the drawings are not necessarily to scale. The same reference numerals refer to corresponding similar parts.

[0026] Figure 1 This is a schematic diagram of the structure of a UBF reactor according to an embodiment of the present invention; Figure 2 This is an X-ray diffraction (XRD) pattern of pyrite with a selected crystal plane of (111) according to an embodiment of the present invention; Figure 3 This is an experimental analysis diagram of the accelerated reaction rate effect of pyrite with crystal plane (111) according to an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of a deep denitrification system according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of a deep denitrification system according to a specific embodiment of the present invention; Figure 6 This is a visualization of the nitrogen removal performance monitoring data of the deep nitrogen removal system according to a specific embodiment 1 of the present invention; Figure 7 This is a material flow analysis diagram of different zones within the UBF reactor of the deep denitrification system according to a specific embodiment 1 of the present invention; Figure 8 The results are based on the deep denitrification performance test results of Comparative Examples 1-3 and Example 1 of this application; The meanings of the numbers in the diagram are as follows: 100-UBF reactor, 200-dosing device, 300-water inlet device, 400-heating device, 500-gas flow meter, 600-temperature detection probe, 110-anaerobic ammonia oxidation thermal zone, 120-coupling zone, 130-deep denitrification protection zone, 140-support zone, 150-three-phase separator, 160-insulation layer, 170-sampling port, 121-first sulfur source dosing port, 122-first sulfur source, 131-filter bag, 132-second sulfur source, 201-first peristaltic pump, 202-first sulfur source dosing tank, 301-second peristaltic pump, 302-sewage collection tank. Detailed Implementation

[0028] The technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. Similar component reference numerals in the drawings represent similar components. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0029] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0030] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0031] This invention provides a schematic diagram of the structure of a UBF reactor, as shown in the embodiment. Figure 1 As shown, the UBF reactor 100 includes a bottom column reaction zone and a three-phase separator 150. The bottom column reaction zone, from bottom to top, includes an anaerobic ammonia oxidation thermal zone 110, a coupling zone 120, and a deep denitrification support zone 130. The coupling zone 120 is equipped with a first sulfur source dosing port 121, and the deep denitrification support zone 130 is equipped with a second sulfur source packing zone consisting of a filter screen 131 for filling with a second sulfur source 132. The UBF reactor 100 is covered with an insulation layer 160. The first sulfur source 122 is thiosulfate, preferably... The amount added is based solely on the average effluent NO3 during the anaerobic ammonia oxidation period. - The -N concentration is determined, and the S / N mass ratio is set to 2.86 according to the reaction equation. The second sulfur source 132 is iron sulfide mineral, and its filling volume accounts for 30% of the overall reaction zone volume of the UBF reactor 100; preferably, the iron sulfide mineral is pyrite, which has a particle size of 2-5 mm and a crystal form of (111). The top and bottom of the UBF reactor 100 are respectively equipped with a three-phase separator 150 and a support zone 140. The support zone 140 is equipped with a glass bead structure for support to prevent sludge blockage and can be inoculated with long-term cultured anaerobic ammonia oxidation sludge. Wastewater enters from port A of the UBF reactor 100 and flows sequentially through the anaerobic ammonia oxidation hot zone 110, the coupling zone 120 and the deep denitrification protection zone 130 for treatment. The gas produced by the reaction (mainly nitrogen) is discharged from the top of the three-phase separator 150, and the treated water is discharged from port B.

[0032] In some specific embodiments, the bottom column reaction zone is equipped with multiple sampling ports 170 fitted with water-stop clamps. This allows for easy access for sampling and testing of water quality (NH4) at each layer. + NO2 - NO3 - (Concentration), monitoring the reaction process.

[0033] In some specific embodiments, reference is made to Figure 2 , Figure 2 The X-ray diffraction (XRD) pattern of pyrite with a selected crystal face (111) according to an embodiment of this application is shown. The diffraction peak corresponding to FeS2 in this pattern matches the standard card PDF#42-1340 (marked with a red vertical line). For sulfur-containing minerals, due to the limitations of direct contact between minerals and microorganisms, the mass transfer process relies on surface reactions and diffusion mass transfer, which easily leads to low mass transfer efficiency, thus adversely affecting the overall denitrification efficiency and requiring a long hydraulic residence time (HRT). In addition, different crystal forms of pyrite have different reaction rates. Taking pyrite as an example, its reaction rate is (111) > (110) > (100). Based on this, in order to avoid situations where the denitrification effect is contrary to the expected effect due to improper crystal form selection, it is necessary to further screen the minerals to ensure that the selected pyrite crystal form (such as pyrite with crystal face (111) in Example 1) can meet the requirements of the denitrification reaction, improve the mass transfer efficiency and denitrification effect, and ensure the stable and efficient operation of the UBF reactor deep denitrification system.

[0034] In the UBF reactor, pyrite achieves a triple functional coupling of physical barrier filtration, accelerated microbial metabolic activity, and deep denitrification protection. Firstly, as a physical barrier filter, pyrite particles (2-5 mm in diameter) form a gradient filtration layer at the top of the reactor, effectively trapping slow-growing anaerobic ammonia-oxidizing bacteria (AnAOB) and sulfur-autotrophic denitrifying bacteria (SOB), thus creating a stable ecological niche for the functional microbial community through this physical trapping effect. For details on the functions of accelerated microbial metabolic activity and deep denitrification protection, please refer to [reference needed]. Figure 3 , Figure 3 An experimental analysis diagram of the accelerated reaction rate effect of pyrite with crystal plane (111) according to an embodiment of the present invention is shown, wherein... Figure 3 (a) shows the enhancing effect of pyrite on the activity of functional microbial communities. Figure 3 (b) Verification of denitrification efficiency driven by pyrite. Figure 3(a) Using bacterial activity (gN / gVSS / d) as an indicator, the changes in anaerobic ammonia oxidation (SAA) and sulfur autotrophic denitrification (SSA) activities were compared. Data were statistically tested (*p<0.05; **p<0.01; ***p<0.001). The results showed that batch experiments confirmed that pyrite can significantly enhance the metabolic activity of functional bacterial communities. Compared with the control group, in the 20 g pyrite addition group, anaerobic ammonia oxidation activity increased from 0.12 gN / gVSS / d to 0.25 gN / gVSS / d, and sulfur autotrophic denitrification activity simultaneously increased by 44% (from 0.09 gN / gVSS / d to 0.13 gN / gVSS / d), indicating that pyrite packed in the reactor can act as a metabolic accelerator, enhancing microbial metabolic activity and nitrogen degradation rate. To verify the deep denitrification compensation effect of pyrite, the reaction zone filling conditions were simulated. With 30% pyrite as the sole sulfur source in a 150 ml serum bottle, 84.3% NO3 was achieved within 72 hours. - -N removal rate (decreased from 50 mg / L to 7.87 mg / L) and 62.8% of NH4+ removal. + The -N removal rate (decreased from 32.53 mg / L to 12.1 mg / L) confirms that it can serve as a self-sustaining sulfur source to drive a complex denitrification process, exhibiting a unique denitrification compensation effect.

[0035] The embodiments of the present invention also propose a method based on Figure 1 The deep denitrification system of the UBF reactor is described, combined with Figure 1 and Figure 4 , Figure 4A schematic diagram of a deep denitrification system according to an embodiment of the present invention is shown. As shown, the system includes a UBF reactor 100, a dosing device 200, a water inlet device 300, a heating device 400, a gas flow meter 500, and a temperature detection probe 600. The UBF reactor 100, from bottom to top, comprises an anaerobic ammonia oxidation thermal zone 110, a coupling zone 120, a deep denitrification support zone 130, a support zone 140 at the bottom, a three-phase separator 150 at the top, and is covered with an outer insulation layer 160. The coupling zone 120 has a first sulfur source dosing port 121. The dosing device 200 is connected to the first sulfur source dosing port 121 and includes a first sulfur source dosing tank 202 and a first peristaltic pump 201. The first sulfur source dosing tank 202 delivers a first sulfur source 122 to the first sulfur source dosing port 121 via the first peristaltic pump 201. The inlet device 300 is connected to the bottom of the UBF reactor 100 and consists of a wastewater collection tank 302 and a second peristaltic pump 301, used to deliver nitrogen-containing wastewater into the UBF reactor 100. The heating device 400 is connected to the insulation layer 160 to provide a stable temperature environment for the operation of the UBF reactor 100. A gas flow meter 500 is installed at the top of the three-phase separator 150 of the UBF reactor 100 to monitor the flow rate and amount of gas generated in the reaction. Preferably, the gas flow meter 500 is a wet gas flow meter. A temperature detection probe 600 penetrates the insulation layer 160 and extends into the UBF reactor 100 to monitor the temperature inside the reactor in real time.

[0036] The embodiments of the present invention propose based on Figure 4 A deep denitrification method for a deep denitrification system, the method comprising: S1. Start the UBF reactor, maintain the water temperature in the reaction zone of the UBF reactor at 30-37℃, inoculate anaerobic ammonia oxidation bacteria in the anaerobic ammonia oxidation hot zone, introduce the first sulfur source into the coupling zone to enrich sulfur autotrophic denitrifying bacteria, and fill the deep denitrification guarantee zone with the second sulfur source. S2. Nitrogenous wastewater is pumped into the UBF reactor through an inlet device, so that the water flows through the anaerobic ammonia oxidation thermal zone, coupling zone and deep denitrification guarantee zone in sequence, and the hydraulic retention time is controlled to be 1.8-3.6 h and the nitrogen load is 2-2.25 g N / L / d.

[0037] In some specific embodiments, step S2 includes: Anaerobic ammonia oxidation occurs in the anaerobic ammonia oxidation hot zone, producing NH4+. + -N and NO2 - -N is converted to N2, while some NO3 is produced. - -N.

[0038] Sulfate-autotrophic denitrifying bacteria in the coupling zone utilize the primary sulfur source to oxidize NO3 produced in the thermal zone using anaerobic ammonia. - -N is partially denitrified into NO2. --N, NO2 - -N and NH4 that has not reacted with the anaerobic ammonium oxidation hot zone + -N is further converted to N2 and some NO3 through anaerobic ammonium oxidation. - -N is directly converted to N2 through complete denitrification; In the deep denitrification protection zone, sulfur-autotrophic denitrifying bacteria utilize the second sulfur source and the remaining first sulfur source to denitrify the NO3 remaining in the coupling zone. - -N is further denitrified into N2, achieving deep nitrogen removal; Among them, the NH4 in the nitrogen-containing wastewater in the influent device + -N: NO2 - -N is (1-1.1):1.

[0039] Example 1 refer to Figure 5 , Figure 5 A deep denitrification system according to a specific embodiment of this application is shown. The system includes a main reaction system and an external sulfur source addition system 502. The temperature of the UBF reactor 501 is maintained by a water bath device 506. The UBF reactor 501 integrates an influent distribution system 503, an Anammox reaction zone L1 (i.e., the anammox thermal zone), a sulfur autotrophic denitrification coupled anammox reaction zone L2 (i.e., the coupling zone), a multi-reduced sulfur-driven sulfur autotrophic denitrification coupled anammox reaction zone L3 (i.e., the deep denitrification guarantee zone), a three-phase separation zone 504, and an effluent system 505. The reaction substrate in the Anammox reaction zone L1 is pumped in by the influent distribution system 503, wherein NH4+... + -N is provided by adding NH4Cl, NO2 - -N is provided by adding NaNO2, and the total nitrogen concentration in the influent is set at 200 mg / L (NO2). - -N concentration 100mg / L, NH4 + -N concentration of 100 mg / L, which is the NH4+ concentration of nitrogen-containing wastewater in the influent water distribution system. + -N: NO2 - -N is 1:1) to match the substrate requirements of anaerobic ammonia oxidizing bacteria. Sulfotrophic denitrification coupled with anaerobic ammonia oxidation in reaction zone L2 of NO3. - -N is provided by metabolic byproducts of the Anammox reaction zone L1; this reaction zone is pumped in... Supplementing the sulfur source, specifically by adopting As a sulfur source, its dosage is based on the average effluent NO3 during the Anammox operation period. - With the N-N concentration determined, the S / N ratio was controlled at 2.86 according to the stoichiometric relationship (eq1) to achieve targeted enrichment of sulfur-autotrophic denitrifying bacteria and drive the sulfur-autotrophic denitrification process. The average effluent NO3 during the Anammox-only operation period was [not specified in the original text].- The -N concentration was 34.4 ± 2.7 mg / L. Based on this average concentration of 34.4 mg / L, the initial... The addition amount was 172 mg / L. The sulfur-autotrophic denitrification coupled with anaerobic ammonia oxidation reaction zone L3, driven by multi-reduced sulfur, was filled with pyrite with a crystal face of (111) using an iron wire filter bag (verified by XRD screening, such as...). Figure 2 As shown in the figure, the pyrite filling rate is 30% of the overall reaction zone of the reactor; no other substrate is added to this zone. Relying on the slow-release sulfur source characteristics and crystal surface catalytic activity of pyrite, the synergistic denitrification efficiency of sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation is enhanced. The reactor operating parameters are set as follows: hydraulic retention time (HRT) 2.4 h, nitrogen load (NLR) 2 g N / L / d. Through zoned functional synergy and precise parameter control, the efficient and stable operation of the deep denitrification process is ensured.

[0040] refer to Figure 6 , Figure 6 A visualization of the nitrogen removal performance monitoring data of the deep nitrogen removal system according to Example 1 of this application is shown. As shown in the figure, the horizontal axis (Duration(d)) represents the operating time of 0-60 days, used to observe the system's treatment stability within a 2-month period; the left vertical axis covers nitrogen concentration (mg / L) and pH, reflecting the distribution of nitrogen speciation in the water and the acid-base environment of the reaction system; the right vertical axis NRE (%) represents the total nitrogen removal efficiency (NRE), with higher values ​​indicating better nitrogen removal performance. Regarding ammonia nitrogen, NH4... + -N inf (The solid green circle indicates the influent ammonia nitrogen concentration, NH4) + -N eff (The green hollow circle) indicates the ammonia nitrogen concentration in the effluent, Average NH4. + -N eff (The solid yellow-green line) shows an average ammonia nitrogen effluent concentration of 1.5 ± 2.0 mg / L, indicating that the UBF system, relying on anaerobic ammonia-oxidizing bacteria, has an excellent ammonia nitrogen removal effect; regarding nitrite nitrogen, NO2... - -N inf (The solid red circle indicates the concentration of nitrite nitrogen in the influent, NO2) - -N eff (The red hollow circle) indicates the effluent nitrite concentration, Average NO2. - -N eff (The solid blue line) shows an average nitrite nitrogen concentration of 1.2 ± 1.6 mg / L in the effluent, indicating that nitrite nitrogen was efficiently converted, specifically through direct reaction by anaerobic ammonia oxidizing bacteria and further reduction by sulfur-autotrophic denitrifying bacteria; regarding nitrate nitrogen, NO3... - -N inf(Purple solid circle) indicates influent nitrate nitrogen and NO3. - -N eff (Purple hollow circle) indicates the effluent nitrate and nitrogen concentration, Average NO3. - -N eff (The solid red line) shows an average nitrate nitrogen concentration of 1.5 ± 0.9 mg / L in the effluent, indicating that nitrate nitrogen is effectively removed and can be indirectly utilized through reduction by sulfur-autotrophic denitrifying bacteria and anaerobic ammonia-oxidizing bacteria; regarding total nitrogen and total nitrogen removal rate, TN... inf (Light purple solid circle) indicates influent ammonia nitrogen, TN eff (Light purple hollow circle) indicates the total nitrogen concentration in the effluent, Average TN eff (Light purple solid line) shows an average effluent total nitrogen of 4.3 ± 2.8 mg / L, and an average total nitrogen removal rate of 97.99% and a maximum of 100% for NRE (gray layer), demonstrating the system's strong deep nitrogen removal capability, which can reduce high concentrations of total nitrogen to low levels, meeting the discharge standards of multiple countries; regarding pH changes, pH inf (The solid red asterisk) indicates the influent pH. eff (Blue hollow asterisk) indicates the outlet pH, Average pH. eff (Yellow solid line) shows that the pH of the reaction system is maintained at 7.05±0.11. Because the alkali produced by anaerobic ammonia oxidation and the alkali consumed by sulfur autotrophic denitrification are dynamically offset, no additional pH adjustment is required, which ensures the metabolic activity of functional bacteria and the stability of system operation. Overall, the UBF reactor shows "stable denitrification, high efficiency and good environment". The concentration of ammonia nitrogen and other effluent is extremely low, and the total nitrogen removal rate is nearly 100%, achieving deep denitrification. The 60-day operating indicators fluctuate little and have strong shock resistance. The stable neutral pH is suitable for the survival of microorganisms.

[0041] Continue to refer to Figure 7 , Figure 7 The diagram shows a mass flow analysis of different zones of the UBF reactor in the deep denitrification system according to Embodiment 1 of this application, wherein... Figure 7 (a), 7(b), and 7(c) are graphs analyzing the contribution of nitrogen mass flow, water quality changes, and nitrogen removal function in different reaction zones, respectively. (a) The UBF reactor forms a three-level metabolic division coupling system along the longitudinal direction (L1→L2→L3). The nitrogen conversion and key reactions in each layer are as follows: L1 layer (Anammox reaction zone), influent contains high concentration of NH4 + -N (accounting for 50.0% of total nitrogen) and NO2 - -N (accounting for 50.0% of total nitrogen) mainly undergoes ① anaerobic ammonium oxidation reaction, The vast majority of NO2 --N is converted to N2 via anaerobic ammonium oxidation (e.g., N2 generation accounts for 82.3% in the L1 layer), but this process produces 26.0 mg / L of NO3 as a byproduct. - -N (accounting for approximately 11%); meanwhile, NH4 + The nitrogen (N) concentration decreased from a high value in the influent to 16.1 mg / L (approximately 6.7%). Due to the alkali-producing characteristics of the anaerobic ammonia oxidation reaction, the pH of the wastewater increased significantly after flowing through the L1 reaction zone. This layer is a high-intensity denitrification zone and is the overall Anammox reaction hot zone, where the denitrification process is completely dominated by Anammox.

[0042] L2 layer (sulfur autotrophic denitrification coupled with anaerobic ammonium oxidation reaction zone), the influent contains NH4 from L1 layer. + -N (16.1 mg / L), byproduct NO3 - -N (26.0 mg / L), and added sodium thiosulfate. During the reaction, the sodium thiosulfate-driven denitrification reaction occurs first, removing the NO3- accumulated in layer L1. - -N is partially denitrified into NO2. - -N, The generated NO2 - -N and remaining NH4 + -N is further removed via anaerobic ammonia oxidation (reaction ①). Furthermore, due to the abundant electron donor from the sulfur source, there is 3.1 mg / L of NO3. - -N is removed by directly generating nitrogen gas through ③ full-process denitrification. This achieves sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation, increasing the proportion of N2 generation (e.g., the N2 generation proportion in the L2 layer reaches 83.6%). Because sulfur autotrophic denitrification is an acid-producing reaction, it consumes a large amount of alkalinity, and the pH of the wastewater decreases significantly after flowing through the L2 functional zone.

[0043] L3 layer (deep denitrification protection zone), the influent contains NO3 remaining from L2 layer. - -N, and a dual sulfur source system consisting of pyrite and residual sodium thiosulfate. In its reaction process, pyrite acts as an enhanced electron transfer carrier, driving sulfur-oxidizing bacteria (SOB) to utilize the residual sodium thiosulfate and pyrite's own sulfur source, reacting with residual NO3. - -N reacts to achieve ④ pyrite-driven sulfur autotrophic denitrification (deep denitrification). Nearly 98.0% of the residual NO3 - -N is converted to N2, and finally NO3 is produced in the water. - -N was only 1.2 mg / L; due to the continuous occurrence of sulfur autotrophic denitrification reaction that produces acid, the pH gradually decreased from L2 to L3, but remained neutral overall.

[0044] Figure 7(b) is a water quality change analysis diagram. As shown in the figure, the total nitrogen (TN) concentration drops sharply as the water flows through the L1→L2→L3 reaction zones. After treatment by the three-stage metabolic coupling system, the high TN concentration in the influent results in extremely low TN in the effluent (close to the deep denitrification standard), demonstrating the system's deep denitrification efficiency. Sulfate Because sulfur sources such as sodium thiosulfate and pyrite are continuously transformed into sulfur through autotrophic denitrification reactions. The concentration of nitrogen continuously increases along the water flow direction. In layer L1, the pH rises significantly due to anaerobic ammonia oxidation producing alkali; in layer L2, the pH drops sharply due to sulfur autotrophic denitrification producing acid and consuming alkali; in layer L3, the pH further decreases slightly due to continuous sulfur autotrophic denitrification producing acid, but remains neutral overall. This reflects a self-regulating mechanism in the reaction system, where Anammox provides alkalinity and SOB consumes it, ensuring stable system operation. The total nitrogen removal rate (NRE) continuously increases as the water flows through L1→L2→L3. Layer L1 achieves initial high-efficiency nitrogen removal with the help of Anammox, while layers L2 and L3 further enhance the nitrogen removal effect through coupled metabolism, ultimately achieving an NRE close to 100%, reaching near-limit nitrogen removal standards.

[0045] Figure 7 (c) is a graph showing the contribution of nitrogen removal function. As shown in the figure, different colors represent the contributions of different nitrogen removal pathways (red for Anammox, blue for sulfur autotrophic denitrification). In layer L1, the nitrogen removal process is completely dominated by Anammox, with a contribution rate of 100%, highlighting its core role as the functional hot zone of Anammox. In layer L2, sulfur autotrophic short-cut denitrification coupled with anaerobic ammonium oxidation is the main nitrogen removal pathway, with Anammox contributing 84.5% and sulfur autotrophic denitrification contributing 15.5%, reflecting the synergistic effect of coupled metabolism. In layer L3, the contribution rate of fully autotrophic denitrification driven by multiple reduced sulfur increases to 60.0%, and Anammox contributes 40%, indicating that after long-term operation and optimization, the system forms a three-level metabolic division of labor coupling system, achieving enhanced deep nitrogen removal function.

[0046] Comparative Example 1 The difference from Example 1 is that no thiosulfate was added to the reactor, and the NH4+ from the nitrogen-containing wastewater in the influent distribution system was [not specified]. + -N: NO2 - With a nitrogen ratio of 1:1.32, the reactor operating parameters were set as follows: hydraulic retention time of 1.2 h, nitrogen load of 4 g N / L / d, and total nitrogen residue of 38.7 ± 3.7 mg / L. Deep denitrification could not be achieved.

[0047] Comparative Example 2 The difference from Example 1 is that the NH4 in the nitrogen-containing wastewater in the influent distribution system... + -N: NO2 -With a nitrogen ratio of 1:1.32, the reactor operating parameters were set as follows: hydraulic retention time of 2.4 h, nitrogen load of 2 g N / L / d, and total nitrogen residue as high as 24.7 ± 4.1 mg / L, which could not achieve deep denitrification.

[0048] Comparative Example 3 The difference from Example 1 is that the NH4 in the nitrogen-containing wastewater in the influent distribution system... + -N: NO2 - With a nitrogen ratio of 1:1.15, the reactor operating parameters were set as follows: hydraulic retention time of 2.4 h, nitrogen load of 2 g N / L / d, and total nitrogen residue of 11.5 ± 2.7 mg / L. Deep denitrification could not be achieved.

[0049] Final Reference Figure 8 , Figure 8 The results of deep denitrification performance tests according to Comparative Examples 1-3 and Example 1 of this application are shown. As shown in the figure, the UBF reactor operation was divided into three stages. The first stage (1-43 days) was a single-function stage (i.e., Comparative Example 1). During the first 43 days, the effluent TN was maintained at 38.7±3.7 mg / L, and the denitrification efficiency (NRE) was 81.9±1.8%. The effluent TN was mainly contributed by nitrates (34.4±2.7 mg / L) produced by the Anammox process. In this stage, sulfur autotrophic denitrification was not activated. At this time, pyrite mainly played the role of sludge interception, and the entire reactor was in Anammox function. In the second stage, thiosulfate was introduced at the L2 dosing port to enrich SOB and activate SAD, aiming to remove nitrates produced by anaerobic ammonia oxidation in L1, while establishing a multifunctional layer in the UBF reactor (i.e., Comparative Example 2). After the addition of thiosulfate, the effluent NO3 - -N decreased to 6.9±4.0 mg / L. Simultaneously, the effluent pH value showed a similar trend to NO3. - -N reduction showed a parallel decreasing trend. This confirms the successful initiation of thiosulfate-driven sulfur autotrophic denitrification. Furthermore, NO2 was observed during the stable operation phase (50-67 days). - -N continued to accumulate, reaching a concentration of 17.0 ± 2.7 mg / L. This is because reducing inorganic sulfur compounds affect NO3-. - -N has a higher affinity than NO2. - -N, thus preferentially driving partial denitrification (NO3) - →NO2 - ).actual The yield (234.2±25.4 mg / L) was lower than the theoretical yield of 291.4 mg / L, indicating that inorganic sulfur compounds were not completely oxidized to sulfates to obtain electrons during denitrification, and that thiosulfate oxidation was incomplete, resulting in intermediate sulfur species. In the third stage, to further achieve the goal of deep denitrification (effluent TN≤5 mg / L), the influent NH4 was adjusted. + / NO2 - The proportion of NH4 in reactor L2 was increased. + -N flux enables the production of NO2 from Anammox coupled with denitrification. - Synergistic denitrification. When NH4 + / NO2 - When the ratio is 1:1.15 (i.e., comparative example 3), the NO2 in the effluent... - -N was 6.9 ± 2.2 mg / L, NRE was 94.6 ± 1.2% (remaining TN was 11.5 ± 2.7 mg / L). On day 100, NH4+ was... + / NO2 - Adjusted to 1:1 (i.e., Example 1 of this application), the final effluent NO2 - -N was 1.2±1.6 mg / L, and the average TN was 4.3±2.8 mg / L, which was significantly lower than the previous two stages (p<0.001). NRE was 98.0±1.3%, and NLR and NRR were basically the same. The TN concentration in the effluent met the strict discharge standards of the major regions.

[0050] Example 2 The difference from Example 1 is that the reactor operating parameters were set as follows: hydraulic retention time of 1.8 h and nitrogen load of 2 g N / L / d.

[0051] Example 3 The difference from Example 1 is that the reactor operating parameters were set as follows: hydraulic retention time of 3.6 h and nitrogen load of 2.25 g N / L / d.

[0052] Example 4 The difference from Example 1 is that the NH4 in the nitrogen-containing wastewater in the influent distribution system... + -N: NO2 - -N is 1.1:1.

[0053] Example 5 The difference from Example 1 is that the pyrite filling rate is 20% of the overall reaction zone of the reactor.

[0054] Example 6 The difference from Example 1 is that the pyrite filling rate is 20% of the overall reaction zone of the reactor, and the reactor operating parameters are set as follows: hydraulic retention time of 1.8 h and nitrogen load of 2 g N / L / d.

[0055] Example 7 The difference from Example 1 is that the pyrite filling rate is 20% of the overall reaction zone of the reactor, and the reactor operating parameters are set as follows: hydraulic retention time of 3.6 h and nitrogen load of 2.25 g N / L / d.

[0056] This application utilizes a single-stage upflow reactor with vertical spatial zoning technology to construct a three-dimensional synergistic reaction architecture. Based on the hydraulic stratification effect, axial functional zoning is achieved: the bottom section is the Anammox reaction hot zone, where nitrate nitrogen byproducts are produced through anaerobic ammonia oxidation; the middle section is a sodium thiosulfate-driven sulfur autotrophic denitrification coupled with anaerobic ammonia oxidation functional zone, using sodium thiosulfate as an electron donor to drive the synergistic effect of sulfur autotrophic denitrification and anaerobic ammonia oxidation, stably accumulating nitrite to provide substrate for anaerobic ammonia oxidation while consuming alkalinity; the upper section is a sulfur autotrophic denitrification enhanced deep denitrification zone composed of a pyrite filter media layer, driven by multiple reduced sulfur sources. With the help of the pyrite filter media layer, multiple sulfur sources rapidly drive functional microorganisms to achieve the goal of deep denitrification. After the introduction of sodium thiosulfate, anaerobic ammonia oxidizing bacteria and sulfur autotrophic denitrifying bacteria are successfully coupled, significantly improving the diversity of the microbial community and enhancing the shock resistance of the reaction system. The proliferation rates of the two bacterial communities are matched to avoid microbial community drift and eliminate the need for external sludge discharge; the top physical isolation design effectively prevents sludge loss. Nitrate nitrogen generated by bottom anaerobic ammonia oxidation is thoroughly removed in the middle and upper sections, ensuring long-term stable operation of the reaction system and maintaining total nitrogen in the effluent consistently below 5 mg / L. The reaction system possesses a self-balancing alkalinity mechanism: the bottom anaerobic ammonia oxidation reaction zone generates alkalinity through metabolism... The alkalinity-providing layer forms an alkalinity-supplying layer to provide alkalinity for the upper autotrophic denitrification; the middle section uses sodium thiosulfate as an electron donor to consume alkalinity and regulate the system alkalinity; the upper pyrite filter layer achieves secondary alkalinity consumption, making the final effluent pH close to neutral, and completing the alkalinity self-balancing. The screened pyrite with a (111) crystal face plays a "three-in-one" role: 2-5 mm particles form a filter layer, retaining AnAOB and SOB, and constructing a stable microbial ecological niche; batch experiments have verified that the pyrite with this crystal face has a significant promoting effect on the anaerobic ammonia oxidation activity, while improving the sulfur autotrophic denitrification efficiency; as a self-sustaining sulfur source, it continues to play a role in the reactor, helping the deep denitrification process.

[0057] It is evident that those skilled in the art can make various modifications and alterations to the embodiments of the present invention without departing from the spirit and scope of the invention. In this way, the invention is also intended to cover such modifications and alterations if they fall within the scope of the claims and their equivalents. The word "comprising" does not exclude the presence of other elements or steps not listed in the claims. The simple fact that certain measures are described in mutually different dependent claims does not indicate that a combination of these measures cannot be used for profit. Any reference numerals in the claims should not be considered as limiting the scope.

Claims

1. A UBF reactor, characterized in that, The UBF reactor comprises, from bottom to top, an anaerobic ammonia oxidation thermal zone, a coupling zone, and a deep denitrification support zone. The coupling zone is equipped with a first sulfur source dosing port, and the deep denitrification support zone is equipped with a second sulfur source packing zone. The outer layer of the UBF reactor is covered with an insulation layer.

2. The UBF reactor according to claim 1, characterized in that, The first sulfur source is thiosulfate, and its addition amount is based on the average effluent NO3 during the anaerobic ammonia oxidation period only. - The concentration of -N determines the reaction rate, and the S / N mass ratio must be ≥2.86 according to the reaction equation. Preferably, the thiosulfate is sodium thiosulfate.

3. The UBF reactor according to claim 1, characterized in that, The second sulfur source is iron sulfide mineral, and the volume of the iron sulfide mineral packing accounts for 20-30% of the total reaction zone volume of the UBF reactor.

4. The UBF reactor according to claim 3, characterized in that, The iron sulfide mineral is pyrite, preferably with a grain size of 2-5 mm and a crystal form of (111).

5. The UBF reactor according to claim 1, characterized in that, The UBF reactor is equipped with a three-phase separator at the top and a support zone at the bottom, and the support zone is equipped with a glass bead structure for support.

6. A deep denitrification system, characterized in that, The device includes the UBF reactor, dosing device, and inlet device as described in any one of claims 1-5, wherein the dosing device is connected to the first sulfur source dosing port, and the inlet device is connected to the bottom of the UBF reactor.

7. The deep denitrification system according to claim 6, characterized in that, The system also includes a gas flow meter and a temperature detection probe. The gas flow meter is located at the top of the three-phase separator of the UBF reactor, and the temperature detection probe penetrates the insulation layer and extends into the UBF reactor.

8. The deep denitrification system according to claim 6, characterized in that, The dosing device includes a first sulfur source dosing tank and a first peristaltic pump, wherein the first sulfur source dosing tank is connected to the first sulfur source dosing port through the first peristaltic pump.

9. A deep denitrification method, characterized in that, The method comprises: utilizing the deep denitrification system according to any one of claims 6-8 S1. Start the UBF reactor, maintain the water temperature in the reaction zone of the UBF reactor at 30-37℃, inoculate anaerobic ammonia oxidation bacteria in the anaerobic ammonia oxidation hot zone, introduce the first sulfur source into the coupling zone to enrich sulfur autotrophic denitrifying bacteria, and fill the deep denitrification guarantee zone with the second sulfur source. S2. Nitrogenous wastewater is pumped into the UBF reactor through the inlet device, so that the water flows sequentially through the anaerobic ammonia oxidation thermal zone, the coupling zone and the deep denitrification guarantee zone, and the hydraulic retention time is controlled to be 1.8-3.6 h and the nitrogen load is 2-2.25 g N / L / d.

10. The deep denitrification method according to claim 9, characterized in that, Step S2 includes: The anaerobic ammonia oxidation hot zone undergoes an anaerobic ammonia oxidation reaction, converting NH4+ into nitrogen. + -N and NO2 - -N is converted to N2, while some NO3 is produced. - -N; The sulfur-autotrophic denitrifying bacteria in the coupling zone utilize a first sulfur source to oxidize NO3 produced in the anammox thermotropic zone. - -N is partially denitrified into NO2. - -N, NO2 - -N unreacted with NH4 in the anaerobic ammonium oxidation hot zone + -N is further converted to N2 through anaerobic ammonium oxidation; and some NO3 is also converted to N2. - -N is directly converted to N2 through complete denitrification; In the deep denitrification protection zone, the sulfur autotrophic denitrifying bacteria utilize the second sulfur source and the remaining first sulfur source to remove the NO3 remaining in the coupling zone. - -N is further denitrified into N2, achieving deep nitrogen removal; The influent device contains nitrogen-containing wastewater with NH4. + -N: NO2 - -N is (1-1.1):1.

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