S n 2- Method and system for deep denitrification mediated effect one-stage PD / A

Abstract

This invention relates to the field of wastewater denitrification technology, and particularly to a method based on S n 2‑ A method and system for one-stage PD / A deep denitrification using a mediated effect includes: constructing a biofilm reaction system by setting up a biofilm carrier component and inoculating it with activated sludge in a continuous flow reactor; simulating the preparation of wastewater effluent containing nitrate nitrogen and introducing a polysulfide solution as an electron donor, then independently and continuously adding both to the continuous flow reactor and mixing them uniformly by stirring; adding ammonia nitrogen to the wastewater effluent and inducing in-situ enrichment of anaerobic ammonia oxidizing bacteria in the biofilm reaction system by staged control of the ammonia nitrogen load in the wastewater effluent; and achieving stable coupling of short-cut denitrification and anaerobic ammonia oxidation in a one-stage continuous flow reactor to simultaneously remove nitrate nitrogen and ammonia nitrogen from the wastewater effluent. This invention features a simple start-up method, stable operation, low dependence on external organic carbon sources, and low sludge yield, making it suitable for deep denitrification treatment of urban wastewater with low carbon-to-nitrogen ratios and wastewater treatment plant effluent.

Description

Technical Field

[0001] This invention relates to the field of wastewater denitrification technology, and particularly to a method based on S n 2- A method and system for one-stage PD / A deep denitrification mediated by the mediating effect. Background Technology

[0002] Currently, eutrophication remains a prominent issue in my country's water bodies, with nitrogen pollution being a significant factor contributing to the degradation of aquatic ecosystems. Nitrogen emissions from wastewater treatment plants are a major source of nitrogen pollution in water bodies. In response, local governments have successively introduced stricter standards for nitrogen pollutant discharge from wastewater treatment plants. However, due to the technological limitations of existing treatment processes and the generally low carbon-to-nitrogen ratio of urban wastewater, achieving high-standard and stable compliance with nitrogen pollutant discharge standards remains a considerable challenge.

[0003] Traditional wastewater treatment processes primarily employ nitrification-denitrification pathways for nitrogen removal. Nitrification relies on continuous aeration, resulting in high energy consumption; denitrification, on the other hand, is highly dependent on the supply of organic carbon sources. Given the low carbon-to-nitrogen ratio of municipal wastewater, denitrification typically requires the addition of additional organic carbon sources to ensure effective nitrogen removal, leading to increased operating costs and higher levels of excess sludge production, thus hindering the economic viability and sustainable operation of wastewater treatment plants.

[0004] Compared to traditional nitrogen removal technologies, biological nitrogen removal technology based on anaerobic ammonium oxidation (ANAO) has advantages such as high nitrogen removal load and no carbon source requirement. ANAO technology utilizes anaerobic ammonium oxidizing bacteria (AnAOB) to remove nitrite nitrogen (NO2) under anoxic conditions. - -N) and ammonia nitrogen (NH4) + Simultaneously, nitrogen (NO3-) is converted into nitrogen gas (N2). This process requires no organic carbon source or aeration and features low sludge production, high nitrogen removal rate, and reduced greenhouse gas emissions. However, anaerobic ammonium oxidation requires NO3-. - -N and NH4 + -N is the substrate, and the reaction matrix is ​​NO3. - The stable acquisition of -N has become a significant bottleneck in the widespread application of anaerobic ammonia oxidation technology. Furthermore, maintaining the activity and dominant position of anaerobic ammonia oxidizing bacteria stably within the reaction system over a long period also presents certain technical challenges.

[0005] Partial denitrification (PD) is a process that uses nitrate nitrogen (NO3) to achieve partial denitrification. - -N) is reduced to NO2 --N can provide a key substrate for anammox. The combined process of short-cut denitrification and anammox is known as the PD / A process. Existing PD / A processes mostly use organic carbon sources as electron donors, achieving deep nitrogen removal through the coupling of heterotrophic short-cut denitrification and anammox. However, adding an external organic carbon source inevitably increases operating costs and places higher demands on system stability and sludge management.

[0006] Compared to traditional heterotrophic denitrification technology, sulfur autotrophic denitrification has advantages such as no need for external organic carbon sources, high nitrogen removal efficiency, safe operation, lower operating costs, and less residual sludge production. However, existing sulfur autotrophic denitrification technologies mostly use elemental sulfur (S). 0 ) or sulfides (S 2- As an electron donor, it suffers from slow electron transfer rate and low sulfur source utilization. Furthermore, the effective coupling of polysulfide-mediated short-cut denitrification with anaerobic ammonia oxidation in a single-stage continuous flow reactor for deep nitrogen removal from wastewater effluent requires further clarification regarding process design and stable operation strategies. Summary of the Invention

[0007] To address at least one of the aforementioned technical problems, this invention proposes a method based on S... n 2- A method and system for one-stage PD / A deep denitrification with mediating effects is proposed to solve the above problems.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of this invention proposes a method based on S n 2- A method for one-stage PD / A deep denitrification mediated by polysulfide (PS) is disclosed, which is applied to a one-stage biofilm treatment system to achieve coupled operation of polysulfide-mediated short-cut denitrification and anaerobic ammonia oxidation within the same continuous flow reactor, wherein anaerobic ammonia oxidizing bacteria are initiated through in-situ enrichment. The method includes the following steps: S1, A biofilm carrier assembly is set up in a continuous flow reactor and activated sludge is inoculated to construct a biofilm reaction system; S2, simulate the preparation of wastewater effluent containing nitrate nitrogen, and introduce polysulfide solution as an electron donor. The wastewater effluent and polysulfide solution are independently and continuously added to the continuous flow reactor. By stirring and mixing evenly, a polysulfide-mediated short-cut denitrification process is realized, converting nitrate nitrogen into nitrite nitrogen. S3, Ammonia nitrogen is added to the effluent of the wastewater treatment plant, and the ammonia nitrogen load of the wastewater treatment plant effluent is adjusted in stages to induce anaerobic ammonia oxidizing bacteria to accumulate in situ in the biofilm reaction system. S4, in the single-stage continuous flow reactor, achieves stable coupling of short-cut denitrification and anaerobic ammonia oxidation, simultaneously removing nitrate nitrogen and ammonia nitrogen from the wastewater treatment plant effluent.

[0009] The inoculated sludge in S1 is sludge from an aerobic tank that has been filtered through a 200-mesh screen, and the biofilm carrier component is attached to the biofilm in a continuous flow reactor for 24 hours.

[0010] Preferably, NaNO3 is used to prepare the wastewater effluent containing nitrate nitrogen in S2, and the ratio of S to nitrate nitrogen is controlled to be 1.2.

[0011] Preferably, the polysulfide solution in S2 is prepared as follows: sulfur powder is added to sodium sulfide solution, and the sodium sulfide solution is continuously stirred for 48 to 72 hours using a magnetic stirrer to ensure that the sulfur powder is completely dissolved, thereby obtaining a polysulfide solution. The chemical reaction formula for obtaining the polysulfide is as follows: Where n is a positive integer greater than 1.

[0012] Preferably, in step S2, the wastewater effluent and polysulfide solution are independently and continuously added to the continuous flow reactor, including: the wastewater effluent and polysulfide solution are respectively transported to the bottom pipeline of the continuous flow reactor by a peristaltic pump for pre-mixing, and then enter the continuous flow reactor from the same wastewater effluent outlet of the continuous flow reactor, and are fully stirred by a stirring device to form a uniform mixture.

[0013] Preferably, the staged regulation of ammonia nitrogen load in the wastewater treatment plant effluent in step S3 includes: Phase I: Maintain ammonia nitrogen concentration in the wastewater effluent ≤5mg / L, and operate until the system nitrite nitrogen accumulation rate stabilizes >60%; Phase II: Increase the ammonia nitrogen concentration in the wastewater effluent to 20-30 mg / L, and operate until the ammonia nitrogen removal rate is stable at >40%; Phase III: Reduce the ammonia nitrogen concentration in the wastewater effluent to 10-15 mg / L to achieve stable coupled operation of the system.

[0014] Preferably, the hydraulic retention time of the wastewater effluent in the continuous flow reactor is 2.5-3.5 h, and the stirring speed is 300-400 r / min.

[0015] A second aspect of the present invention proposes a one-stage PD / A deep denitrification system based on polysulfide-mediated effects for implementing the method described in the first aspect, comprising: A continuous flow reactor is used to provide reaction space for short-cut denitrification and anaerobic ammonia oxidation. The continuous flow reactor is a single-stage biofilm continuous flow reactor, and biofilm components for attaching and growing short-cut denitrifying bacteria and anaerobic ammonia oxidizing bacteria are spaced apart inside the continuous flow reactor. An inlet tank is used to store inlet water containing nitrate nitrogen and ammonia nitrogen, and the inlet tank is connected to the continuous flow reactor via a peristaltic pump; A feed bottle for storing polysulfide solutions is connected to the continuous flow reactor via a peristaltic pump. A magnetic stirrer is installed at the bottom of the continuous flow reactor and is used to stir the solution in the continuous flow reactor by driving the rotor to rotate magnetically. The outlet is located on the side wall near the top of the continuous flow reactor and is used to discharge the treated effluent.

[0016] An overflow outlet is provided on the side wall of the continuous flow reactor and is symmetrical to the outlet. It is used to maintain the stability of the liquid level in the continuous flow reactor under continuous water inlet conditions.

[0017] Preferably, the biofilm carrier assembly includes a support disposed within the continuous flow reactor and nonwoven fabrics fixed to the support at parallel intervals.

[0018] Preferably, the continuous flow reactor is made of polyvinyl chloride pipe with an inner diameter of 130 mm, the support is made of glass fiber, and the non-woven fabric is spaced 15 mm apart.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention constructs a biofilm reaction system by setting up a biofilm carrier assembly and inoculating it with activated sludge in a continuous flow reactor; and prepares a solution containing NO3 according to the effluent quality of the wastewater treatment plant. - -N inlet water, introducing S n 2- As electron donors, both are introduced separately into a continuous flow reactor for biofilm, and mixed uniformly by stirring to achieve NO3- in the biofilm system. - -N to NO2 - -N short-range denitrification process; addition of NH4 to the influent + -N, and regulate the influent NH4 + -N loading induces in-situ enrichment of anaerobic ammonia oxidizing bacteria; thereby achieving stable coupling of short-cut denitrification and anaerobic ammonia oxidation processes in a single-stage continuous flow reactor, and realizing the reduction of NO3 in the influent. - -N, NH4 +Highly efficient simultaneous removal of -N. Compared with traditional denitrification processes, the technical solution of this application is simple to start up, has a stable operation, low dependence on external organic carbon sources, and low sludge production rate. It is suitable for deep denitrification treatment of urban sewage with low carbon-to-nitrogen ratio and sewage treatment plant effluent. Attached Figure Description

[0020] Figure 1 Based on S n 2- A schematic diagram of the process flow for a one-stage PD / A deep denitrification method mediated by the effect; Figure 2(a) and Figure 2(b) are based on S n 2- A schematic diagram of the nitrogen conversion effect during process operation in a one-stage PD / A deep denitrification method mediated by the PD / A method; Figure 3 Based on S n 2- A schematic diagram of TN removal rate and denitrification contribution rate during process operation in a one-stage PD / A deep denitrification method mediated by the effect; Figure 4 Based on S n 2- A schematic diagram of the abundance changes of nitrogen cycle-related functional genes in biomembrane systems during a one-step PD / A deep denitrification method mediated by the effect. Figure 5 Based on S n 2- A schematic diagram of the system structure of a one-stage PD / A deep denitrification system with a guiding effect. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments of the present invention.

[0022] Example 1 For ease of understanding, the relevant chemical symbols and their corresponding Chinese names in the text are explained below: S n 2- Polysulfides; Na2S n Sodium polysulfide; Na2S: Sodium sulfide; S: Sulfur or sulfur powder; NO3 - : Nitrate ion; NO3 - -N: Nitrate nitrogen; NO2 - : Nitrite ions; NO2 - -N: Nitrite nitrogen; NH4 + : Ammonium ion; NH4 +-N: Ammonia nitrogen; N2: Nitrogen gas; AnAOB: Anaerobic ammonia oxidizing bacteria; PD: Short-cut denitrification; A: Anaerobic ammonia oxidation; PD / A: Short-cut denitrification coupled with anaerobic ammonia oxidation; NarGHI: Membrane-bound nitrate reductase complex gene; NapAB: Periplasmic nitrate reductase complex gene; HzsABC: Hydrazine synthase complex gene; hdh: Hydrazine dehydrogenase gene; HRT: Hydraulic retention time; TN: Total nitrogen; S / N: Sulfur-to-nitrogen ratio; MLSS: Mixed liquor suspended solids concentration; COD: Chemical oxygen demand; DO: Dissolved oxygen.

[0023] Please refer to Figure 1 and Figure 5 As shown, this embodiment provides a method based on S n 2- The method for one-stage PD / A deep denitrification mediated by the mediating effect needs to be explained. Specifically, the "S" mentioned in this application... n 2- "Mediated effect" refers to: polysulfide ions (S... n 2- In biological denitrification (n=2-6), it not only participates in redox reactions as an electron donor, but also in the gradual oxidation process (S... n 2- →S 0 →SO4 2- This can maintain a stable electron supply rate in the system. More importantly, S n 2- It selectively inhibits nitrite reductase (Nir) while having little effect on nitrate reductase (Nar), thus achieving NO3... - →NO2 - Short-range transformation. "S" n 2- "Mediation effect" is a common sulfide (S) 2- ) or elemental sulfur (S) 0 It does not have.

[0024] This method is applied to a single-stage biofilm treatment system to achieve the coupled operation of polysulfide-mediated short-range denitrification and anaerobic ammonia oxidation in the same continuous flow reactor, wherein anaerobic ammonia oxidizing bacteria are initiated through in-situ enrichment.

[0025] The method includes the following steps: S1. A biofilm carrier assembly is set up in a continuous flow reactor and activated sludge is inoculated to construct a biofilm reaction system.

[0026] It should be noted that in this embodiment, the inoculated sludge comes from the secondary sedimentation tank of an urban wastewater treatment plant. Before inoculation, it is filtered multiple times through a 200-mesh sieve to remove larger inorganic particulate impurities such as sand from the raw sludge, ensuring the homogeneity of the sludge and the stability of the continuous flow reactor operation. The biofilm carrier assembly is placed inside the biofilm continuous flow reactor to provide space for microorganisms to attach and grow.

[0027] Activated sludge from the wastewater treatment system was inoculated into a continuous flow biofilm reactor to construct a basic short-cut denitrification biofilm reaction system. During inoculation, the agitator was turned on to enhance mass transfer conditions within the continuous flow reactor, which was conducive to the uniform attachment and stable growth of microorganisms on the carrier surface, thus providing a stable and efficient microbial community foundation for subsequent sludge acclimation and biological treatment processes. After 24 hours of sludge inoculation to complete biofilm formation, the reactor entered a continuous influent operation phase, with a hydraulic retention time (HRT) set at 3 hours, during which unformed suspended sludge was discharged.

[0028] S2 simulates the preparation of wastewater effluent containing nitrate nitrogen, and introduces a polysulfide solution as an electron donor. The wastewater effluent and the polysulfide solution are independently and continuously added to a continuous flow reactor. Through stirring and mixing, a polysulfide-mediated short-cut denitrification process is achieved, converting nitrate nitrogen into nitrite nitrogen.

[0029] It should be noted that in this embodiment, NaNO3 is used to prepare the wastewater effluent containing nitrate nitrogen, and the nitrate nitrogen (NO3) is controlled. - The concentration of S-N was approximately 30 mg / L, and the ratio of S to nitrate nitrogen (S / N) was controlled at 1.2.

[0030] The preparation method of the above-mentioned polysulfide solution is as follows: sulfur powder is added to a sodium sulfide solution, and the sodium sulfide solution is continuously stirred for 48 to 72 hours using a magnetic stirrer to ensure that the sulfur powder is completely dissolved, thereby obtaining a polysulfide solution. The chemical reaction formula for obtaining the polysulfide is: Where n is a positive integer greater than 1. n can be 2, 3, 4, ...

[0031] Given the active proliferation and vigorous metabolism of denitrifying microorganisms, which easily trigger the denitrification process prematurely during the influent stage, in this embodiment, the wastewater effluent and polysulfide solution are separately pre-mixed by continuously pumping them to the bottom pipeline of the continuous flow reactor using peristaltic pumps. Then, they enter the continuous flow reactor from the same inlet and are thoroughly stirred by a stirring device to form a homogeneous mixture. Under stirring and mixing conditions, the influent substrate and S... n 2- Evenly dispersed and in full contact with the biofilm system, it facilitates the domestication and enrichment of functional microorganisms, thereby promoting NO3. --N to NO2 - Selective transformation of -N, gradually establishing S n 2- This mediated short-cut denitrification process effectively avoids unexpected reactions during the influent stage, thus promoting the stable operation of the short-cut denitrification process.

[0032] This step enables the continuous addition and enhanced mixing of polysulfide solutions, providing a stable electron donor for the subsequent denitrification reaction while maintaining the uniformity and stability of the reaction environment within the reactor.

[0033] S3, ammonia nitrogen is added to the effluent of the wastewater treatment plant, and the ammonia nitrogen load of the wastewater treatment plant effluent is adjusted in stages to induce the in-situ enrichment of anaerobic ammonia oxidizing bacteria in the biofilm reaction system.

[0034] It is understandable that NH4 enters the water. + -N and S n 2- Mediating short-cut denitrification to continuously provide NO2 - The substrate conditions of -N work together to create a suitable substrate environment for the growth of AnAOB, inducing its in-situ proliferation, enriching and forming functional bacterial communities, without the need for exogenous inoculation of anaerobic ammonia oxidation sludge.

[0035] In this embodiment, S is carried out simultaneously in the same biofilm continuous flow reactor. n 2- The mediated short-cut denitrification reaction and anaerobic ammonium oxidation reaction reduce the NO2 produced by the short-cut denitrification process. - -N and NH4 in the influent + -N undergoes coupling transformation to achieve NO3 - -N and NH4 + The synchronous conversion of -N to N2 completes deep denitrification.

[0036] Table 1 As can be seen from the main influent parameters of the continuous flow reactor shown in Table 1, the above-mentioned staged regulation of ammonia nitrogen load in the wastewater treatment plant effluent in this embodiment includes: Phase I: Maintain influent ammonia nitrogen concentration ≤5mg / L, and operate until the system nitrite nitrogen accumulation rate stabilizes >60%; no additional ammonium ions are added to the influent during this phase, and the system primarily uses sulfur (S). n 2- The primary focus is on mediated short-range denitrification reactions, with the aim of establishing a stable short-range denitrification process to achieve NO3 reduction. - -N→NO2 - The conversion of -N provides a substrate source for subsequent AnAOB.

[0037] Phase II: Increase the influent ammonia nitrogen concentration to 20-30 mg / L and operate until the ammonia nitrogen removal rate stabilizes above 40%; ammonium ions are added to the influent during this phase to react with sulfur. n 2- Mediating the continuous production of NO2 from short-cut denitrification - -N forms the substrate system required for anaerobic ammonia oxidation, thereby inducing the gradual enrichment and proliferation of AnAOB.

[0038] Phase III: The influent ammonia nitrogen concentration is reduced to 10-15 mg / L to maintain long-term stable system operation. This phase reduces the ammonium ion load, ensuring ammonium ion supply is equal to NO2. - The production rates are matched to achieve stable coupling of short-cut denitrification and anaerobic ammonium oxidation processes.

[0039] In this embodiment, the one-stage PD / A biofilm system is designed according to the influent NH4 + Figure 2(a) shows the nitrogen conversion in the three operating stages based on -N concentration, and Figure 2(b) shows the denitrification contribution rate. The TN removal rate and denitrification contribution rate are shown in Figure 2(a). Figure 3 As shown.

[0040] Specifically, Phase I (days 1-16) is the short-range denitrification stable operation phase, with an average influent NO3 level of [missing information]. - -N concentration is 30.5 mg / L, NH4 + The -N concentration is 0 mg / L. At this point, short-cut denitrification mainly occurs in the continuous flow reactor, producing NO2. - The accumulation of -N, on average NO3 - -N removal rate was 82.4%, and average NO2 in effluent was [missing information]. - -N is 15.6 mg / L.

[0041] It should be noted that existing polysulfide-assisted activated sludge denitrification technologies (such as CN202510469487.6) mainly rely on complete denitrification, with the electron transfer pathway being NO3. - →NO2 - →N2, intermediate product NO2 - -N is rapidly reduced, failing to provide a stable substrate source for anaerobic ammonium oxidation. In contrast, this application utilizes S... n 2- The mediating effect makes the system more favorable for NO3. - -N to NO2 - -N selective conversion, and to some extent slows down NO2. - Further reduction of -N, thus achieving NO2 - The stable accumulation of -N promotes the coupling of short-cut denitrification with anaerobic ammonium oxidation.

[0042] NH4 was added to the feed water of the continuous flow reactor on the 17th day. + -N, Average NO3 influent to the Stage II system - -N concentration was 30.7 mg / L, NH4+ + The NO3- concentration in the system is 24.2 mg / L. - -N removal rate was 82.1%, maintaining a good level. Due to the low amount of AnAOB in the system, NH4+... + -N concentration remained almost unchanged, and over the following 78 days, the system's response to NH4+ was... + -N was almost completely removed, NH4 + -N removal rate was only 3.8%. This is because the system contains a relatively high amount of NO2. - -N, add NH4 to the influent + After the -N reaction, AnAOB had sufficient reaction substrate, promoting its enrichment. The continuous flow reactor operated for 93 days, and NH4... + -N removal rate rose to 10.3%, and then continued to increase. However, from day 133 onwards, NH4... + -N removal efficiency tends to stabilize, with an average value of 48.1%, and effluent NH4 + -N concentration remained at a high level of 12.8 mg / L. Meanwhile, the effluent NO2... - -N concentrations were low (average 1.29 mg / L), indicating that NO2... - -N has been almost completely consumed, resulting in the remaining NH4 + -N cannot be removed further.

[0043] It should be noted that this invention achieved efficient enrichment of AnAOB within 93 days and stable coupling of short-cut denitrification and anaerobic ammonium oxidation within 133 days. Compared to previously reported elemental sulfur autotrophic PD / A systems, this invention has a shorter start-up period. Furthermore, this invention constructs a NO2-based... - Accumulation rate (>60%) and NH4 + The quantization threshold switching strategy for removal rate (>40%) provides strong process controllability and facilitates engineering scale-up and automated control.

[0044] Phase III begins on day 151, with the introduction of NH4 into the water. + -N concentration adjusted to approximately 13 mg / L. Influent NH4 content reduced. + -N load followed by effluent NH4 + -N concentration decreased significantly. During this stage, the system maintained excellent denitrification performance, and NO3 concentration decreased significantly. - -N, NH4 +The average removal rates of NO2- and TN were 87.4%, 82.6%, and 84.6%, respectively. - The average N-N concentration was 1.0 mg / L. During the stable operation of Stage II, anaerobic ammonia oxidation contributed an average of 62.8% to TN removal; when the influent NH4+... + After the -N concentration decreased, its contribution rate remained between 62.5% and 65.3%.

[0045] In this invention, anaerobic ammonia oxidation contributes an average of over 62% to total nitrogen removal, making it the dominant nitrogen removal pathway in the system. This demonstrates that the invention successfully achieves a stable coupling between short-cut denitrification and anaerobic ammonia oxidation, rather than the traditional complete denitrification, while also achieving simultaneous deep nitrogen removal of both nitrate and ammonia nitrogen.

[0046] like Figure 4 As shown in the figure, this example analyzed the gene expression activity of key processes in the microbial nitrogen cycle of a single-stage PD / A biofilm system on days 16 and 170 of operation. The results show that the expression activity involved in NO3... - -N to NO2 - The -N conversion process is associated with NarGHI and NapAB. After more than 170 days of continuous system operation, compared with day 16, the enrichment of NarGHI and NapAB genes showed an increasing trend on day 170, with the abundance of narG, narH, and narI genes increasing by 79.8%, 63.4%, and 111.8%, respectively; simultaneously, the abundance of napA and napB genes also increased by 83.0% and 94.5%, respectively. Anaerobic ammonia oxidation is closely related to the HzsABC and hdh genes. Compared with day 16, the abundance of hzsA, hzsB, hzsC, and hdh genes all increased significantly on day 170, with increases of 2428.6%, 2135.9%, 298.9%, and 1567.7%, respectively.

[0047] Based on the above functional gene analysis results, it can be concluded that this embodiment verifies "S" at the molecular biology level. n 2- "Mediation effect": S n 2- It can target and enhance the short-cut denitrification pathway, and successfully enrich AnAOB in situ, enabling process start-up without exogenous inoculation.

[0048] Comparative Example 1 To verify the present invention S n 2- The technical effects of this application as an electron donor for sulfur autotrophic short-range denitrification are illustrated by comparative examples.

[0049] In this comparative example, S from Example 1 will be used. n2- The solution was replaced with Na2S solution as the electron donor, while the influent water quality, dosing method, device structure, and operating conditions remained consistent with Example 1. Under these conditions, the denitrification performance and reaction contribution rate of the one-stage biofilm reactor system at different operating stages are shown in Table 2.

[0050] Table 2 The results show that when Na2S is used as the electron donor, NO2 in the system in stage I... - -N accumulates at a low level, failing to form a stable short-range denitrification process. After entering Stage II, although NO3... - -N removal remains at a high level, but NH4 + -N was hardly removed, indicating that the anaerobic ammonium oxidation reaction failed to establish itself effectively. Meanwhile, NO2 in the system... - -N concentrations remained at low levels, making it difficult to provide a stable substrate source for anaerobic ammonium oxidation. In Stage III, NH4+... + Although the nitrogen removal efficiency was improved, the contribution of anaerobic ammonia oxidation to TN removal remained low, and the system was still dominated by denitrification. In summary, this comparative example did not achieve satisfactory nitrogen removal, proving that the S-type nitrogen used in this invention... n 2- It has significant advantages over ordinary sulfides.

[0051] Example 2 Please refer to Figure 5 As shown, a one-stage PD / A deep denitrification system based on polysulfide-mediated effect is used to implement the method as described in Example 1. The system mainly includes: a continuous flow reactor 4, an inlet tank 1, a peristaltic pump 2, a drug inlet bottle 3, a biofilm carrier assembly 5, a stirrer 7, a rotor 6, an outlet 8, and an overflow outlet 9.

[0052] Specifically, the continuous flow reactor is used to provide reaction space for short-cut denitrification and anaerobic ammonia oxidation. The continuous flow reactor is a single-stage biofilm continuous flow reactor, in which biofilm components for the attachment and growth of short-cut denitrifying bacteria and anaerobic ammonia oxidizing bacteria are arranged at intervals.

[0053] It should be noted that in this embodiment, the continuous flow reactor is symmetrically equipped with an outlet and an overflow outlet at the top, which can be located 200mm from the bottom of the continuous flow reactor. The outlet is used to discharge the treated effluent, and samples are taken from the discharged treated effluent for NO3 testing. - -N, NH4 +Monitoring of key indicators such as -N. The overflow port is used to maintain a stable liquid level in the continuous flow reactor under continuous water intake conditions. In this embodiment, the effective volume of the continuous flow reactor 4 is 2.5L, and it is made of polyvinyl chloride pipe with an inner diameter of 130mm.

[0054] To facilitate thorough mixing of the solution in the continuous flow reactor, this embodiment includes a magnetic stirrer at the bottom of the reactor. The rotor is driven to rotate by magnetic force, thereby causing the solution in the continuous flow reactor to rotate synchronously and achieve thorough mixing between different solutions.

[0055] To facilitate the attachment and growth of short-range denitrifying bacteria and anaerobic ammonia-oxidizing bacteria, the biofilm carrier assembly in this embodiment includes a support frame disposed within a continuous flow reactor and non-woven fabrics fixed to the support frame at parallel intervals. The support frame is made of glass fiber, and the non-woven fabrics are spaced 15 mm apart.

[0056] The inlet tank is used to store inlet water containing nitrate nitrogen and ammonia nitrogen. The inlet tank is connected to the continuous flow reactor via a peristaltic pump.

[0057] The inlet bottle is used to store the polysulfide solution and is connected to the continuous flow reactor via a peristaltic pump.

[0058] The system provided in this embodiment can achieve S within the same continuous flow reactor. n 2- The coupled operation of mediated short-cut denitrification and anaerobic ammonia oxidation enhances deep nitrogen removal from wastewater. This system is easy to start up, operates stably, has low dependence on external organic carbon sources, and produces relatively low sludge. It is suitable for deep nitrogen removal treatment of urban wastewater with low carbon-to-nitrogen ratios and wastewater treatment plant effluent, and has promising industrial application prospects and promotional value.

[0059] Comparative Example 2 To verify the advantages and applicability of the single-stage PD / A system of the present invention, this application provides Comparative Example 2 for illustration.

[0060] In this comparative example, the single-stage PD / A system in Example 1 was replaced with a two-stage PD / A system, mainly comprising a short-cut denitrification reactor and an anaerobic ammonia oxidation reactor arranged in series. Both reactors adopted the same biofilm cultivation method and non-woven fabric component structure as in Example 1. Furthermore, the electron donor, influent addition method, and operating conditions remained consistent with Example 1.

[0061] During operation, wastewater effluent and polysulfide solutions first enter the PD reactor, where they are then processed in the S... n 2- NO3-mediated realization - -N to NO2 -The process involves the conversion and accumulation of nitrogen (N-O); subsequently, the effluent from the PD reactor enters the A reactor and undergoes anaerobic ammonia oxidation. The denitrification performance and reaction contribution rate of the two-stage combined process during stable operation are shown in Table 3.

[0062] Table 3 The results showed that the overall nitrogen removal efficiency of the two-stage PD / A system was close to that of the PD / A system. However, the two-stage system requires separate short-cut denitrification reactors and anaerobic ammonium oxidation reactors, resulting in a more complex system structure; and additional control of NO2 between the two stages is also necessary. - -N and NH4 + The matching relationship between -N requires high operational control. In contrast, the single-stage PD / A system described in this invention can achieve coupled operation of short-cut denitrification and anaerobic ammonia oxidation in the same reactor, maintaining high nitrogen removal efficiency while offering advantages such as simple process flow, high equipment integration, and convenient operation control.

[0063] The above description is a specific implementation of the embodiments of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A method based on S n 2- A one-stage PD / A deep denitrification method with mediating effects is characterized by, The method is applied to a single-stage biofilm treatment system to achieve coupled operation of polysulfide-mediated short-cut denitrification and anaerobic ammonia oxidation within the same continuous flow reactor, wherein anaerobic ammonia oxidizing bacteria are initiated through in-situ enrichment. The method includes the following steps: S1, A biofilm carrier assembly is set up in a continuous flow reactor and activated sludge is inoculated to construct a biofilm reaction system; S2, simulate the preparation of wastewater effluent containing nitrate nitrogen, and introduce polysulfide solution as an electron donor. The wastewater effluent and polysulfide solution are independently and continuously added to the continuous flow reactor. By stirring and mixing evenly, a polysulfide-mediated short-cut denitrification process is realized, converting nitrate nitrogen into nitrite nitrogen. S3, Ammonia nitrogen is added to the effluent of the wastewater treatment plant, and the ammonia nitrogen load of the wastewater treatment plant effluent is adjusted in stages to induce anaerobic ammonia oxidizing bacteria to accumulate in situ in the biofilm reaction system. S4, in the single-stage continuous flow reactor, achieves stable coupling of short-cut denitrification and anaerobic ammonia oxidation, simultaneously removing nitrate nitrogen and ammonia nitrogen from the wastewater treatment plant effluent.

2. The S-based method according to claim 1 n 2- A one-stage PD / A deep denitrification method with mediating effects is characterized by, The inoculated sludge in S1 is sludge from an aerobic tank that has been filtered through a 200-mesh screen, and the biofilm carrier component is attached to the biofilm in a continuous flow reactor for 24 hours.

3. The S-based method according to claim 1 n 2- A one-stage PD / A deep denitrification method with mediating effects is characterized by, In the S2, NaNO3 is used to prepare the wastewater effluent containing nitrate nitrogen, and the ratio of S to nitrate nitrogen is controlled to be 1.

2.

4. The S-based method according to claim 1 n 2- A one-stage PD / A deep denitrification method with mediating effects is characterized by, The preparation method of the polysulfide solution in S2 is as follows: sulfur powder is added to sodium sulfide solution, and the sodium sulfide solution is continuously stirred for 48 to 72 hours using a magnetic stirrer to ensure that the sulfur powder is completely dissolved, thereby obtaining a polysulfide solution. The chemical reaction formula for obtaining polysulfides is as follows: Where n is a positive integer greater than 1.

5. The S-based method according to claim 1 n 2- A one-stage PD / A deep denitrification method with mediating effects is characterized by, The wastewater treatment plant effluent and polysulfide solution in S2 are independently and continuously added to the continuous flow reactor, including: the wastewater treatment plant effluent and polysulfide solution are respectively transported to the bottom pipeline of the continuous flow reactor by a peristaltic pump for premixing, and then enter the continuous flow reactor from the same wastewater treatment plant effluent outlet, and are fully stirred by a stirring device to form a uniform mixture.

6. The S-based method according to claim 1 n 2- A one-stage PD / A deep denitrification method with mediating effects is characterized by, The phased regulation of ammonia nitrogen load in wastewater effluent mentioned in S3 includes: Phase I: Maintain ammonia nitrogen concentration in the wastewater effluent ≤5mg / L, and operate until the system nitrite nitrogen accumulation rate stabilizes >60%; Phase II: Increase the ammonia nitrogen concentration in the wastewater effluent to 20-30 mg / L, and operate until the ammonia nitrogen removal rate is stable at >40%; Phase III: Reduce the ammonia nitrogen concentration in the wastewater effluent to 10-15 mg / L to achieve stable coupled operation of the system.

7. The S-based method according to claim 1 n 2- A one-stage PD / A deep denitrification method with mediating effects is characterized by, The hydraulic retention time of the wastewater effluent in the continuous flow reactor is 2.5-3.5 h, and the stirring speed is 300-400 r / min.

8. Based on S n 2- A one-stage PD / A deep denitrification system with mediating effects, used to implement the method as described in any one of claims 1-7, characterized in that, include: A continuous flow reactor (4) is used to provide reaction space for short-cut denitrification and anaerobic ammonia oxidation. The continuous flow reactor is a single-stage biofilm continuous flow reactor. Biofilm components (5) for attaching and growing short-cut denitrifying bacteria and anaerobic ammonia oxidizing bacteria are provided at intervals in the continuous flow reactor. The inlet tank (1) is used to store inlet water containing nitrate nitrogen and ammonia nitrogen. The inlet tank is connected to the continuous flow reactor via a peristaltic pump. A drug inlet bottle (3) is used to store a polysulfide solution, and the drug inlet bottle is connected to the continuous flow reactor via a peristaltic pump; A magnetic stirrer (7) is installed at the bottom of the continuous flow reactor and is used to stir the solution in the continuous flow reactor by driving the rotor (6) to rotate by magnetic force. The outlet (8) is located on the side wall near the top of the continuous flow reactor and is used to discharge the treated effluent; An overflow port (9) is provided on the side wall of the continuous flow reactor and is symmetrical to the outlet. It is used to maintain the stability of the liquid level in the continuous flow reactor under continuous water intake conditions.

9. According to claim 8, based on S n 2- A one-stage PD / A deep denitrification system with mediating effects is characterized by, The biofilm carrier assembly includes a support frame disposed within the continuous flow reactor and nonwoven fabrics fixed to the support frame at parallel intervals.

10. Based on S according to claim 9 n 2- A one-stage PD / A deep denitrification system with mediating effects is characterized by, The continuous flow reactor is made of polyvinyl chloride pipe with an inner diameter of 130 mm, the support is made of glass fiber, and the non-woven fabric is spaced 15 mm apart.

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