Sulfate type anaerobic hydroxylamine oxidation efficient denitrification method

Abstract

The invention discloses a sulfate type anaerobic hydroxylamine oxidation efficient denitrification method, and belongs to the field of industrial sewage treatment. The invention aims to solve the problems that the reaction is unstable, the denitrification efficiency is low and microbial communities are easily inhibited when the existing denitrification technology is used for treating complex wastewater containing hydroxylamine and sulfate. The method comprises the following steps: 1, preparing inoculated sludge; 2, setting operation conditions of the reactor; and 3, operating the reactor. The method is used for acid salt type anaerobic hydroxylamine oxidation efficient denitrification.

Description

Technical Field

[0001] This invention belongs to the field of industrial wastewater treatment. Background Technology

[0002] With the continuous increase in industrial and municipal wastewater discharge, the problem of combined nitrogen and sulfur pollution is becoming increasingly prominent. Wastewater from industries such as chemical, coking, smelting, pharmaceutical, and landfill leachate often contains high concentrations of hydroxylamine (NH2OH) and sulfate (SO42-). 2- Pollutants such as hydrogen sulfide and heavy metal leaching can cause eutrophication of receiving water bodies if discharged directly without adequate treatment. This can lead to secondary pollution, posing a threat to ecosystems and human health.

[0003] Currently, the treatment of nitrogen- and sulfur-containing wastewater often employs a coupled process of sulfur autotrophic short-cut denitrification and anaerobic ammonia oxidation (Anammox). In this process, sulfur autotrophic short-cut denitrification uses sulfides and other substances as electron donors to denitrate nitrates (NO3-). - ) reduces and generates nitrite (NO2) - This process, in conjunction with Anammox, further enhances nitrogen removal efficiency. However, such processes are generally significantly constrained by environmental conditions and intermediate products: NO2 - Salt, as a key electron acceptor in Anammox, is susceptible to substrate fluctuations during operation, and its reaction rate is often limited by NO2. - Insufficient supply. In addition, the system is sensitive to operating parameters such as pH, temperature and dissolved oxygen, often exhibiting long start-up and acclimatization periods and insufficient operational stability, thus limiting its engineering application.

[0004] In recent years, researchers have gradually discovered that NH2OH plays a unique intermediate role in the nitrogen cycle system. Hydroxylamine can serve as an intermediate product of ammonia oxidation, and under specific conditions, it can also be directly oxidized by microorganisms to nitrogen gas (N2), thus bypassing NO2. - The process enables a novel anaerobic hydroxylamine oxidative denitrification pathway. This pathway offers advantages such as rapid reaction rate, low energy requirement, and flexibility in substrate selection, providing a new technological direction for efficient autotrophic denitrification.

[0005] However, existing anaerobic hydroxylamine oxidation systems still face multiple challenges in engineering applications: (1) Complex reaction mechanism and poor stability of functional microbial communities: The anaerobic hydroxylamine oxidation process involves multiple functional microorganisms such as hydroxylamine oxidizing bacteria and sulfate-reducing bacteria. Their metabolic pathways are interactively coupled and easily affected by fluctuations in influent water quality and environmental conditions, leading to system instability and difficulty in long-term operation. (2) Significant inhibitory effect of intermediate products: During sulfate reduction, intermediate products such as sulfides, sulfites, and elemental sulfur are often generated. These substances have potential toxicity to anaerobic hydroxylamine oxidizing bacteria, inhibiting their metabolic activity and causing a decrease in reaction rate. (3) Lack of substrate regulation mechanism: The conversion of hydroxylamine as an electron donor or acceptor strongly depends on the redox state of the reaction system. However, existing technologies lack effective substrate supply and electron flow regulation methods, resulting in large fluctuations in system operation and low reaction efficiency.

[0006] In summary, existing denitrification technologies still suffer from problems such as unstable reactions, low denitrification efficiency, and easy suppression of microbial communities when dealing with complex wastewater containing hydroxylamine and sulfate. Summary of the Invention

[0007] This invention aims to address the problems of unstable reaction, low denitrification efficiency, and easy inhibition of microbial communities in existing denitrification technologies when dealing with complex wastewater containing hydroxylamine and sulfate. Therefore, it provides a sulfate-based anaerobic hydroxylamine oxidation method for highly efficient denitrification.

[0008] A highly efficient denitrification method using sulfate-based anaerobic hydroxylamine oxidation is described, comprising the following steps:

[0009] I. Preparation of inoculum sludge:

[0010] Anaerobic ammonia oxidation granular sludge, secondary sedimentation tank activated sludge and river bottom sediment are pretreated and then mixed evenly to obtain a mixed liquid.

[0011] The concentration of suspended solids in the mixture is 8.5 g SS L. -1 ~10.5g SS L -1 ;

[0012] The mass ratio of the anaerobic ammonia oxidation granular sludge, the secondary sedimentation tank activated sludge, and the riverbed sediment is 2:(0.6~1.2):(0.6~1.2);

[0013] II. Reactor operating condition settings:

[0014] Before inoculation, residual oxygen in the reactor was removed and an anaerobic environment was established. The reactor was set to operate in a dual-inlet mode, with hydroxylamine solution and sulfate solution as inlets. The flow rate was controlled by a peristaltic pump. Then, the mixed solution was introduced into the reactor as inoculum.

[0015] III. Reactor Operation:

[0016] ① From day 1 to day 21 of reactor operation, the hydraulic retention time is set to 16 to 18 days to maintain a low hydroxylamine influent load;

[0017] ② From day 22 to day 75 of reactor operation, the hydraulic retention time is set to 11 to 15 days to further increase the hydroxylamine influent load;

[0018] ③ From day 76 to day 168 of reactor operation, the hydraulic retention time is set to 9 to 11 days, and the influent load is increased to a high hydroxylamine level, thus completing the sulfate-type anaerobic hydroxylamine oxidation high-efficiency denitrification method.

[0019] The beneficial effects of this invention are:

[0020] The sulfate-based anaerobic hydroxylamine oxidation method for high-efficiency nitrogen removal described in this invention achieves efficient conversion and long-term stable removal of nitrogen and sulfur pollutants by constructing a synergistic system of hydroxylamine oxidation and sulfate reduction. Specific effects are as follows:

[0021] (a) Highly efficient removal of nitrogen and sulfur pollutants, significantly improving denitrification performance: In the initial stage of operation (0~21d), the hydroxylamine removal rate reached 100%, and the reactor was able to completely remove hydroxylamine from the influent; the sulfate removal rate was stable at 3.5 mg SL. -1 d -1 The sulfate concentration in the effluent remained stable at 13.3 mg / L. -1 As the hydroxylamine influent loading rate gradually increased to 14.4 mg NL -1 d -1 The reactor was still able to effectively remove hydroxylamine, with a removal rate of 14.4 mg NL. -1 d -1 Furthermore, the sulfate removal rate recovered to 3.2 mg SL. -1 d -1 Compared to the common problem of "sulfide accumulation and reaction inhibition under high load" in traditional sulfate-type anaerobic ammonium oxidation systems, the reactor of this invention achieves efficient coupling of nitrogen-sulfur electron flow through the anaerobic hydroxylamine oxidation process, effectively overcoming the system's susceptibility to inhibition.

[0022] (b) Good adaptability and tolerance, significantly mitigating the effects of substrate toxicity: This invention significantly reduces the inhibitory effect of hydroxylamine on functional microbial communities by gradually increasing the hydroxylamine loading in stages. Experimental results show that the microbial community gradually adapts to changes in hydroxylamine loading during operation, and the system is effective at an influent hydroxylamine loading rate of 5.7 mg NL. -1 d -1 Increased to 14.4 mg NL -1 d -1Under these conditions, the reactor maintained a stable hydroxylamine removal rate and simultaneous sulfate reduction efficiency. Furthermore, no toxic H2S accumulation was detected in the system, and XPS analysis showed that the reaction products were predominantly elemental sulfur (SO), indicating that this invention effectively avoided the problem of hydrogen sulfide byproduct inhibition. In summary, the reactor maintained efficient operation under long-term high-load conditions, demonstrating excellent substrate tolerance and long-term operational stability.

[0023] (c) High-efficiency enrichment of functional microorganisms, overcoming community instability: 16S rRNA sequencing analysis revealed that the microbial community structure was gradually optimized during continuous operation of the reactor, exhibiting a significant enrichment effect of functional microorganisms. After 150 days of operation, the relative abundance of Proteobacteria increased to 32.8%, becoming the dominant phylum in the system; Chloroflexi (16.5%) and Acidobacteriota (9.2%) were significantly enriched, promoting the dynamic balance between sulfur oxidation and sulfur reduction processes; the relative abundance of anaerobic ammonia oxidation-related bacteria Candidatus Brocadia and Candidatus Anammoxoglobus increased from less than 5% initially to over 10%, indicating their core role in hydroxylamine oxidation and nitrogen reduction reactions; the abundance of filamentous bacteria OLB17 increased from 1.8% to 6.3%, enhancing the structural stability of sludge particles and further improving the system's shock resistance. These results demonstrate that the present invention achieves synergistic enrichment and stable symbiosis of anaerobic hydroxylamine oxidizing bacteria and sulfate-reducing bacteria, overcoming the shortcomings of unstable microbial communities and unreliable reactivity in traditional denitrification systems.

[0024] (d) Superior overall performance and significant potential for engineering applications: The sulfate-based anaerobic hydroxylamine oxidation system of this invention can achieve simultaneous and efficient removal of hydroxylamine and sulfur pollutants under conditions of no external carbon source and low energy consumption: hydroxylamine removal rate >99%, sulfate removal rate is 3.2 mg SL -1 d -1 The reaction system can operate continuously and stably for more than 168 days without significant biomass loss; the operating energy consumption is reduced by 35% to 45% compared with the traditional denitrification process.

[0025] Therefore, this invention not only achieves highly efficient coupling of hydroxylamine oxidation and sulfate reduction in terms of reaction mechanism, but also demonstrates significant advantages in engineering practice, including high efficiency, low energy consumption, and stable operation. This invention provides a novel, sustainable, scalable, and long-term stable process for anaerobic biological denitrification of wastewater with high nitrogen and high sulfur content. Detailed Implementation

[0026] Specific Implementation Method 1: This implementation method is a sulfate-type anaerobic hydroxylamine oxidation high-efficiency denitrification method, which is carried out according to the following steps:

[0027] I. Preparation of inoculum sludge:

[0028] Anaerobic ammonia oxidation granular sludge, secondary sedimentation tank activated sludge and river bottom sediment are pretreated and then mixed evenly to obtain a mixed liquid.

[0029] The concentration of suspended solids in the mixture is 8.5 g SS L. -1 ~10.5g SS L -1 ;

[0030] The mass ratio of the anaerobic ammonia oxidation granular sludge, the secondary sedimentation tank activated sludge, and the riverbed sediment is 2:(0.6~1.2):(0.6~1.2);

[0031] II. Reactor operating condition settings:

[0032] Before inoculation, residual oxygen in the reactor was removed and an anaerobic environment was established. The reactor was set to operate in a dual-inlet mode, with hydroxylamine solution and sulfate solution as inlets. The flow rate was controlled by a peristaltic pump. Then, the mixed solution was introduced into the reactor as inoculum.

[0033] III. Reactor Operation:

[0034] ① From day 1 to day 21 of reactor operation, the hydraulic retention time is set to 16 to 18 days to maintain a low hydroxylamine influent load;

[0035] ② From day 22 to day 75 of reactor operation, the hydraulic retention time is set to 11 to 15 days to further increase the hydroxylamine influent load;

[0036] ③ From day 76 to day 168 of reactor operation, the hydraulic retention time is set to 9 to 11 days, and the influent load is increased to a high hydroxylamine level, thus completing the sulfate-type anaerobic hydroxylamine oxidation high-efficiency denitrification method.

[0037] In step two of this specific implementation method, the flow rates of the two inlet water streams are precisely controlled by independent peristaltic pumps to meet the regulation requirements under different nitrogen and sulfur load conditions.

[0038] The reactor described in this specific embodiment adopts a vertical cylindrical structure, with a cylindrical top, a straight middle section, and a conical bottom. This configuration facilitates liquid-solid separation and promotes sludge settling and reflux, thereby enhancing the biomass retention capacity. The reactor is equipped with a water bath jacket, the inlet and outlet of which are connected to a constant-temperature water bath to maintain the system temperature at 30±2℃, providing a suitable growth environment for sulfate-reducing bacteria and anaerobic hydroxylamine-oxidizing bacteria. A three-phase separator is installed at the top of the reactor to effectively separate gas, liquid, and sludge, and to retain and reflux poorly settling biological particles to prevent biomass loss and prolong the retention time of functional bacteria. An inlet is located at the bottom of the reactor for inputting the substrate solution; an outlet and a gas outlet are located at the top. The outlet is connected to a gas bag to maintain the anaerobic environment of the system and achieve gas-liquid pressure balance. A circulating pump is connected to the reactor body to drive the internal circulation of the reaction liquid, ensuring sufficient mixing and mass transfer of hydroxylamine, sulfate, and intermediate products, thereby promoting the stable progress of the synergistic reaction. The inlet pump is connected to the storage bottle, which enables a stable and continuous inlet of water containing hydroxylamine and sulfate solutions, meeting the metabolic needs of microorganisms and maintaining the system's operational balance.

[0039] A circulation pump is installed at the bottom of the reactor pipeline to drive the reaction solution to circulate and mix within the system, thereby ensuring uniform distribution of substrates such as hydroxylamine and sulfate and promoting efficient microbial metabolism. An internal pH meter monitors the system's pH in real time and can be adjusted by adding external acid or alkali solutions when necessary to maintain the pH within the range of 7.0–8.0, ensuring the stable activity of the functional microorganisms.

[0040] In this embodiment, the influent pump continuously injects wastewater containing hydroxylamine and sulfate into the reactor body, the circulation pump ensures uniform mixing of the substrate and sludge, the constant temperature water bath maintains a stable temperature, the pH meter monitors the acidity and alkalinity in real time, and the effluent is discharged into the effluent bottle for collection through the top outlet. This configuration can maintain stable operation even under high-load influent conditions containing hydroxylamine and sulfate, effectively avoiding oxygen interference and biomass loss, and providing an efficient and stable operating environment for the synergistic reaction of sulfate reduction and anaerobic hydroxylamine oxidation.

[0041] This embodiment aims to enrich and stabilize functional microorganisms such as sulfate-reducing bacteria and anaerobic hydroxylamine-oxidizing bacteria, and the reactor adopts a continuous flow operation mode.

[0042] In this specific embodiment, the pH value of the reactor is maintained between 7.0 and 8.0, and the temperature is maintained at 30±2°C throughout the entire operation cycle, so as to ensure the metabolic stability of functional microorganisms and the long-term operational efficiency of the system.

[0043] The sulfate-based anaerobic hydroxylamine oxidation high-efficiency nitrogen removal method described in this embodiment achieves efficient simultaneous removal of hydroxylamine and sulfate under anaerobic conditions through synergistic optimization of continuous flow operation and reactor structure. Compared with traditional nitrogen removal processes, this method systematically improves upon issues such as poor system stability, significant inhibition of sulfide intermediate products, and lack of substrate regulation mechanisms. This embodiment can rapidly enrich and form a synergistic microbial community centered on anaerobic hydroxylamine oxidizing bacteria and sulfate-reducing bacteria. Under long-term operation, the nitrogen and sulfur removal rates remain above 90%, demonstrating excellent operational stability and shock resistance. This method and reactor effectively overcome key defects in existing technologies, providing a new technical pathway for efficient, low-carbon, and sustainable biological nitrogen removal from complex nitrogen- and sulfur-containing wastewater.

[0044] This embodiment aims to address the problems of unstable reaction processes, low denitrification efficiency, and susceptibility to microbial community inhibition in existing denitrification technologies when treating complex wastewater containing both hydroxylamine and sulfate. Therefore, it provides a highly efficient denitrification method based on sulfate-based anaerobic hydroxylamine oxidation. This method targets wastewater systems containing both hydroxylamine and sulfate, achieving efficient and stable removal of nitrogen and sulfur pollutants by enhancing the metabolic coupling and synergistic electron transfer between sulfate-reducing bacteria and anaerobic hydroxylamine-oxidizing bacteria.

[0045] The beneficial effects of this embodiment are:

[0046] The sulfate-based anaerobic hydroxylamine oxidation high-efficiency nitrogen removal method described in this embodiment achieves efficient conversion and long-term stable removal of nitrogen and sulfur pollutants by constructing a synergistic system of hydroxylamine oxidation and sulfate reduction. The specific effects are as follows:

[0047] (a) Highly efficient removal of nitrogen and sulfur pollutants, significantly improving denitrification performance: In the initial stage of operation (0~21d), the hydroxylamine removal rate reached 100%, and the reactor was able to completely remove hydroxylamine from the influent; the sulfate removal rate was stable at 3.5 mg SL. -1 d -1 The sulfate concentration in the effluent remained stable at 13.3 mg / L. -1 As the hydroxylamine influent loading rate gradually increased to 14.4 mg NL -1 d -1 The reactor was still able to effectively remove hydroxylamine, with a removal rate of 14.4 mg NL. -1 d -1 Furthermore, the sulfate removal rate recovered to 3.2 mg SL. -1 d -1 Compared to the common problem of "sulfide accumulation and reaction inhibition under high load" in traditional sulfate-type anaerobic ammonium oxidation systems, the reactor in this embodiment achieves efficient coupling of nitrogen-sulfur electron flow through the anaerobic hydroxylamine oxidation process, effectively overcoming the system's susceptibility to inhibition.

[0048] (b) Good adaptability and tolerance, significantly mitigating the effects of substrate toxicity: This implementation method significantly reduced the inhibitory effect of hydroxylamine on the functional microbial community by gradually increasing the hydroxylamine loading in stages. Experimental results showed that the microbial community gradually adapted to the changes in hydroxylamine loading during operation, and the system was able to adapt to the changes in hydroxylamine loading at an influent loading rate of 5.7 mg NL. -1 d -1 Increased to 14.4 mg NL -1 d -1 Under these conditions, the reactor maintained a stable hydroxylamine removal rate and simultaneous sulfate reduction efficiency. Simultaneously, no accumulation of toxic H2S was detected in the system, and XPS analysis showed that the reaction products were mainly elemental sulfur (SO), indicating that this embodiment effectively avoided the problem of hydrogen sulfide byproduct inhibition. In summary, the reactor maintained efficient operation under long-term high-load conditions, demonstrating excellent substrate tolerance and long-term operational stability.

[0049] (c) High-efficiency enrichment of functional microorganisms, overcoming community instability: 16S rRNA sequencing analysis revealed that the microbial community structure was gradually optimized during continuous operation of the reactor, exhibiting a significant enrichment effect of functional microorganisms. After 150 days of operation, the relative abundance of Proteobacteria increased to 32.8%, becoming the dominant phylum in the system; Chloroflexi (16.5%) and Acidobacteriota (9.2%) were significantly enriched, promoting the dynamic balance between sulfur oxidation and sulfur reduction processes; the relative abundance of anaerobic ammonia oxidation-related bacteria Candidatus Brocadia and Candidatus Anammoxoglobus increased from less than 5% initially to over 10%, indicating their core role in hydroxylamine oxidation and nitrogen reduction reactions; the abundance of filamentous bacteria OLB17 increased from 1.8% to 6.3%, enhancing the structural stability of sludge particles and further improving the system's shock resistance. These results indicate that this implementation method achieves synergistic enrichment and stable symbiosis of anaerobic hydroxylamine oxidizing bacteria and sulfate-reducing bacteria, overcoming the shortcomings of unstable microbial communities and unreliable reaction performance in traditional denitrification systems.

[0050] (d) Excellent overall performance and significant potential for engineering applications: The sulfate-based anaerobic hydroxylamine oxidation system of this embodiment can achieve simultaneous and efficient removal of hydroxylamine and sulfur pollutants under conditions of no external carbon source and low energy consumption: hydroxylamine removal rate >99%, sulfate removal rate is 3.2 mg SL -1 d -1 The reaction system can operate continuously and stably for more than 168 days without significant biomass loss; the operating energy consumption is reduced by 35% to 45% compared with the traditional denitrification process.

[0051] Therefore, this embodiment not only achieves highly efficient coupling of hydroxylamine oxidation and sulfate reduction in terms of reaction mechanism, but also demonstrates significant advantages in engineering practice, including high efficiency, low energy consumption, and stable operation. This embodiment provides a novel, sustainable, scalable, and long-term stable process route for anaerobic biological denitrification of wastewater with high nitrogen and high sulfur content.

[0052] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the particle size of the anaerobic ammonia oxidation granular sludge mentioned in step one is 0.5 mm or larger, and the SVI is 20 mL / g to 40 mL / g. Everything else is the same as in Specific Implementation Method One.

[0053] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the MLSS of the activated sludge in the secondary sedimentation tank mentioned in step one is 7000 mg / L to 10000 mg / L. Everything else is the same as in Specific Implementation Method One or Two.

[0054] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the mass percentage of gravel in the riverbed sediment mentioned in Step One is less than 15%. Everything else is the same as Specific Implementation Methods One to Three.

[0055] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the pretreatment of the anaerobic ammonia oxidation granular sludge and the activated sludge in the secondary sedimentation tank in step one involves washing with a culture medium; the pretreatment of the riverbed sediment in step one involves mixing the riverbed sediment with the culture medium evenly, and then filtering it through a screen to remove coarse particulate impurities. Everything else is the same as in Specific Implementation Methods One to Four.

[0056] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One through Five in that: in step three①, maintaining a low hydroxylamine influent load specifically means that the hydroxylamine influent load rate is 3.8 mg NL. -1 d -1 ~5.7mg NL -1 d -1 The sulfate influent loading rate was 2.3 mg SL. -1 d -1 ~3.9mg SL -1 d -1 Everything else is the same as in specific implementation methods one through five.

[0057] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One through Six in that: in step three, step two, the hydroxylamine influent load is further increased, specifically to a hydroxylamine influent load rate of 8.6 mg NL. -1 d -1 ~11.5mg NL -1 d-1 The sulfate influent loading rate was 2.3 mg SL. -1 d -1 ~3.9mg SL -1 d -1 The rest is the same as in specific implementation methods one through six.

[0058] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One through Seven in that: in step three ③, increasing the hydroxylamine influent load to a high level specifically means that the hydroxylamine influent load rate is 13.8 mg NL. -1 d -1 ~14.4mg NL -1 d -1 The sulfate influent loading rate was 2.3 mg SL. -1 d -1 ~3.9mg SL -1 d -1 Everything else is the same as in specific implementation methods one through seven.

[0059] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: in steps three ①, ②, and ③, the reactor pH value is 7.0~8.0 during the operating cycle. Everything else is the same as in Specific Implementation Methods One to Eight.

[0060] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the temperature in steps three (①, ②, and ③) is 30±2℃ during the operating cycle. Everything else is the same as in Specific Implementation Methods One to Nine.

[0061] The beneficial effects of the present invention are verified using the following embodiments:

[0062] Example 1:

[0063] A highly efficient denitrification method using sulfate-based anaerobic hydroxylamine oxidation is described, comprising the following steps:

[0064] I. Preparation of inoculum sludge:

[0065] Anaerobic ammonia oxidation granular sludge, secondary sedimentation tank activated sludge and river bottom sediment are pretreated and then mixed evenly to obtain a mixed liquid.

[0066] The concentration of suspended solids in the mixture was 8.6 ± 0.2 g SS L. -1 ;

[0067] The mass ratio of the anaerobic ammonia oxidation granular sludge, the secondary sedimentation tank activated sludge, and the riverbed sediment is 2:1:1.

[0068] II. Reactor operating condition settings:

[0069] Before inoculation, high-purity nitrogen (purity ≥99.9%) was introduced into the reactor for 15 minutes to remove residual oxygen and establish an anaerobic environment. The reactor was set to operate in a dual-inlet mode, with hydroxylamine solution and sulfate solution as inlets. The flow rate was controlled by a peristaltic pump. The mixed solution was then introduced into the reactor as inoculum.

[0070] III. Reactor Operation:

[0071] ① From day 1 to day 21 of reactor operation, the hydraulic retention time was set to 17.5 days to maintain a low hydroxylamine influent load;

[0072] ② From day 22 to day 75 of reactor operation, the hydraulic retention time was set to 14 days to further increase the hydroxylamine influent load;

[0073] ③ From day 76 to day 168 of reactor operation, the hydraulic retention time is set to 10 days, and the influent load is increased to a high hydroxylamine level, thus completing the sulfate-type anaerobic hydroxylamine oxidation high-efficiency denitrification method.

[0074] The anaerobic ammonia oxidation granular sludge mentioned in step one comes from a stable Anammox reactor in a wastewater treatment plant, with an average particle size of 0.68 mm and an SVI of 31.2 mL / g.

[0075] The activated sludge in the secondary sedimentation tank mentioned in step one comes from the secondary sedimentation tank of a municipal wastewater treatment plant, with an MLSS of 8735 mg / L.

[0076] The riverbed sediment mentioned in step one was collected from natural riverbeds at a sampling depth of 50cm to 60cm, and the mass percentage of sand and gravel in the riverbed sediment was 9.8%.

[0077] The pretreatment of the anaerobic ammonia oxidation granular sludge and the secondary sedimentation tank activated sludge in step one involves washing with a culture medium to remove residual substrates and impurities.

[0078] The pretreatment of riverbed sediment in step one involves mixing the riverbed sediment with the culture medium until they are homogeneous, and then filtering them through a sieve to remove coarse particulate impurities.

[0079] Step 3① further increases the hydroxylamine influent load, specifically by setting the hydroxylamine influent load rate to 5.7 mg NL. -1 d -1 The sulfate influent loading rate was 3.9 mg SL. -1 d -1 .

[0080] In step 3②, increasing the influent load to a high hydroxylamine level specifically means that the hydroxylamine influent load rate is 11.5 mg NL. -1 d -1 The sulfate influent loading rate was 3.9 mg SL.-1 d -1 .

[0081] Step 3, ③, specifically increasing the hydroxylamine influent load to a high hydroxylamine influent load rate of 14.4 mg NL. -1 d -1 The sulfate influent loading rate was 3.9 mg SL. -1 d -1 .

[0082] In steps 3, ①, ②, and ③, the reactor pH is 7.0~8.0 and the temperature is 30±2℃.

[0083] The culture medium used in the pretreatment was a freshly prepared inorganic salt basal medium with the following composition: 0.04 g / L. -1 KH2PO4, 0.08g L -1 MgCl2•6H2O, 0.30g L -1 CaCl2•2H2O, 0.50g L -1 KHCO3; and add 1 mL of trace element I solution and 1 mL of trace element II solution per liter of culture medium. The formula for trace element I solution is: 15.0 g / L -1 EDTA, 0.01g / L -1 H3BO3, 0.43g L -1 ZnSO4•7H2O, 0.24g L -1 CoCl2•6H2O, 0.99g L -1 MnCl2•4H2O, 0.25g L -1 CuSO4, 0.22 g L -1 NaMoO4•2H2O, 0.21g L -1 NaSeO4•10H2O, 0.19g L -1 NiCl2•6H2O, 0.05g L -1 The formula for NaWO4•2H2O; trace element II solution is (in g L) -1 (Calculated): 5.00g L -1 EDTA, 5.00g / L -1 FeSO4•7H2O.

[0084] To reduce the inhibitory effect of hydroxylamine on the microbial community, promote the gradual adaptation of functional microorganisms, and ensure stable system operation, this embodiment adopts a phased acclimatization operation method, dividing the operation process into three stages (days 1-21, 22-75, and 76-168). During the start-up acclimatization stage (days 1-21), the reactor operates with a low substrate influent load, where the hydroxylamine influent load rate is 5.7 mg NL. -1 d -1 The sulfate influent loading rate was 3.9 mg SL. -1 d -1 The purpose of setting a low load in this stage is to avoid the rapid accumulation of hydroxylamine in the reaction system, which could cause acute toxicity shock. This allows the microbial community to gradually adapt to the complex environment containing hydroxylamine and sulfate, laying the foundation for subsequent metabolic synergy and stable operation. Entering the load-increasing acclimatization stage (days 22-75), while keeping the sulfate influent load rate constant, the hydroxylamine influent load rate is gradually increased (from 8.6 mg NL). -1 d -1 Increased to 11.5mg NL -1 d -1 The objective of this phase is to promote the adaptive screening and enrichment of key functional bacteria under higher substrate pressure without altering the sulfate supply level, and to facilitate the stable coupling of denitrification and sulfate reduction processes within the system. During the high-load stable operation phase (days 76-168), the hydroxylamine influent loading rate was further increased to 14.4 mg NL. -1 d -1 The microbial community demonstrated tolerance and long-term operational stability under higher hydroxylamine exposure and substrate loading conditions. This verified its shock resistance and functional maintenance capabilities under high-load conditions, facilitating the microbial community's transition from "adaptation-enrichment" to "stability-enhancement," and enabling continuous and efficient nitrogen and sulfur removal operation under hydroxylamine and sulfate-containing wastewater conditions.

[0085] Comprehensive operational data shows that the reactor effectively removed hydroxylamine from the influent in all three stages. The hydroxylamine removal rate was basically consistent with the influent load rate of the corresponding stage, and the effluent hydroxylamine concentration remained consistently below the detection limit. In the initial stage of operation (0-21 days), the hydroxylamine removal rate reached 100%, indicating that the reactor could completely remove hydroxylamine from the influent. As the hydroxylamine influent load rate gradually increased to 14.4 mg NL... -1 d -1 The reactor was still able to effectively remove hydroxylamine, with a removal rate of 14.4 mg NL. -1 d -1 The sulfate removal rate stabilized at approximately 3.5 mg SL during the start-up phase. -1 d -1The sulfate concentration in the effluent is approximately 13.3 mg SL. -1 During the load increase phase, the sulfate removal rate decreased to approximately 2.6 mg SL. -1 d -1 ~3.2mg SL -1 d -1 The sulfate concentration in the effluent rises to approximately 25 mg SL. -1 ~44mg SL -1 During the high-load stable operation phase, the sulfate removal rate recovered to approximately 3.2 mg SL. -1 d -1 This indicates that the microbial community can be re-established and maintain sulfate-reducing activity after acclimatization; and because the microorganisms reduce hydroxylamine to ammonia nitrogen, the ammonia nitrogen concentration in the effluent accumulates to 28.6 mg NL at the end of the start-up phase. -1 And during the load increase phase, it rose to 36.9 mg NL at one point. -1 It then tends to stabilize (approximately 30 mg NL). -1 After entering the high-load stable operation phase, the concentration gradually decreased and fell below the detection limit on day 141. In summary, by gradually increasing the influent load of hydroxylamine, the instantaneous toxic shock of the system can be effectively reduced and the functional microbial community can be gradually adapted and enriched, thereby significantly improving the microbial acclimatization effect and ensuring the stable operation of the reactor under high-load conditions.

Claims

1. A highly efficient denitrification method using sulfate-based anaerobic hydroxylamine oxidation, characterized in that... It is done in the following steps: I. Preparation of inoculum sludge: Anaerobic ammonia oxidation granular sludge, secondary sedimentation tank activated sludge and river bottom sediment are pretreated and then mixed evenly to obtain a mixed liquid. The concentration of suspended solids in the mixture is 8.5 g SS L. -1 ~10.5g SS L -1 ; The mass ratio of the anaerobic ammonia oxidation granular sludge, the secondary sedimentation tank activated sludge, and the riverbed sediment is 2:(0.6~1.2):(0.6~1.2); II. Reactor operating condition settings: Before inoculation, residual oxygen in the reactor was removed and an anaerobic environment was established. The reactor was set to operate in a dual-inlet mode, with hydroxylamine solution and sulfate solution as inlets. The flow rate was controlled by a peristaltic pump. Then, the mixed solution was introduced into the reactor as inoculum. III. Reactor Operation: ① From day 1 to day 21 of reactor operation, the hydraulic retention time is set to 16 to 18 days to maintain a low hydroxylamine influent load; ② From day 22 to day 75 of reactor operation, the hydraulic retention time is set to 11 to 15 days to further increase the hydroxylamine influent load; ③ From day 76 to day 168 of reactor operation, the hydraulic retention time is set to 9 to 11 days, and the influent load is increased to a high hydroxylamine level, thus completing the sulfate-type anaerobic hydroxylamine oxidation high-efficiency denitrification method.

2. The method for efficient nitrogen removal by sulfate-type anaerobic hydroxylamine oxidation according to claim 1, characterized in that... The anaerobic ammonia oxidation granular sludge mentioned in step one has a particle size of 0.5 mm or more and an SVI of 20 mL / g to 40 mL / g.

3. The sulfate-type anaerobic hydroxylamine oxidation high-efficiency denitrification method according to claim 1, characterized in that... The MLSS of the activated sludge in the secondary sedimentation tank mentioned in step one is 7000 mg / L to 10000 mg / L.

4. The sulfate-type anaerobic hydroxylamine oxidation high-efficiency denitrification method according to claim 1, characterized in that... The mass percentage of sand and gravel in the riverbed sediment mentioned in step one is less than 15%.

5. The method for efficient nitrogen removal by sulfate-type anaerobic hydroxylamine oxidation according to claim 1, characterized in that... The pretreatment of anaerobic ammonia oxidation granular sludge and secondary sedimentation tank activated sludge in step one involves washing with a culture medium; the pretreatment of riverbed sediment in step one involves mixing the riverbed sediment with the culture medium evenly and then filtering it through a screen to remove coarse particulate impurities.

6. The method for efficient nitrogen removal by sulfate-type anaerobic hydroxylamine oxidation according to claim 1, characterized in that... Step 3① maintains a low hydroxylamine influent load, specifically a hydroxylamine influent load rate of 3.8 mg NL. -1 d -1 ~5.7mg NL -1 d -1 The sulfate influent loading rate was 2.3 mg SL. -1 d -1 ~3.9mg SL -1 d -1 .

7. The sulfate-type anaerobic hydroxylamine oxidation high-efficiency denitrification method according to claim 1, characterized in that... Step 3, ②, further increases the hydroxylamine influent load, specifically by setting the hydroxylamine influent load rate to 8.6 mg NL. -1 d -1 ~11.5mg NL -1 d -1 The sulfate influent loading rate was 2.3 mg SL. -1 d -1 ~3.9mg SL -1 d -1 .

8. The method for efficient nitrogen removal by sulfate-type anaerobic hydroxylamine oxidation according to claim 1, characterized in that... Step 3, ③, specifically increasing the hydroxylamine influent load to a high hydroxylamine influent load rate of 13.8 mg NL. -1 d -1 ~14.4mg NL -1 d -1 The sulfate influent loading rate was 2.3 mg SL. -1 d -1 ~3.9mg SL -1 d -1 .

9. The method for efficient nitrogen removal by sulfate-type anaerobic hydroxylamine oxidation according to claim 1, characterized in that... In steps 3, ①, ②, and ③, the reactor pH value is 7.0~8.0 during the operation cycle.

10. The method for efficient nitrogen removal by sulfate-type anaerobic hydroxylamine oxidation according to claim 1, characterized in that... In steps 3, ①, ②, and ③, the temperature is 30±2℃ during the operating cycle.