A device for autotrophic denitrification of wastewater

Abstract

This utility model relates to the field of wastewater treatment technology, specifically an autotrophic denitrification wastewater treatment device, including an influent tank, a sulfate-type autotrophic denitrification bioreactor, an ultrafiltration membrane module, a nanofiltration membrane module, and an effluent tank. It solves problems such as high aeration volume, high treatment cost, and substandard effluent in wastewater treatment. This wastewater treatment device eliminates the need for aeration, utilizing sulfate-type anaerobic ammonia oxidation and sulfur autotrophic denitrification to achieve autotrophic denitrification. Ultrafiltration membranes remove organic matter and colloids, providing fine pretreatment for subsequent nanofiltration. Nanofiltration membranes concentrate and reflux sulfate in the concentrate, providing reaction conditions for sulfate-type biological denitrification. The nanofiltration effluent meets the quality requirements for reclaimed water.

Description

Technical Field

[0001] This utility model relates to the field of wastewater treatment technology, specifically to an autotrophic denitrification wastewater treatment device. Background Technology

[0002] Domestic sewage treatment refers to the process of removing pollutants from domestic sewage through physical, chemical, and biological technologies, so that the treated water meets discharge standards or reuse requirements, and ultimately achieves water resource recycling or safe discharge.

[0003] Among related technologies, a search revealed an intelligent aeration denitrification system (publication number CN111635006A) that utilizes a multi-point influent method to fully leverage the carbon source carried in the influent to participate in the denitrification reaction in the downstream anoxic tank, reducing the nitrate nitrogen content in the effluent and decreasing the nitrification liquor recirculation flow, thereby reducing energy consumption. Compared with traditional A2 / O treatment systems, this system can more fully utilize the carbon source in the influent, achieving precise aeration and recirculation, and avoiding energy waste and unstable or even substandard water quality caused by excessive or insufficient aeration and recirculation.

[0004] However, the aforementioned wastewater treatment processes, especially biological denitrification, require nitrification-denitrification reactions and rely on aeration and influent carbon sources for nitrogen removal. Aeration consumes a lot of energy, has high operating costs, and generates significant carbon emissions. When the influent carbon source is insufficient, external carbon sources (such as sodium acetate or glucose) need to be added, leading to high reagent consumption. Utility Model Content

[0005] The purpose of this invention is to provide an autotrophic denitrification wastewater treatment device to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: An autotrophic denitrification wastewater treatment device includes an inlet tank, a nanofiltration membrane module, and an outlet tank; The inlet tank is connected to a sulfate-type autotrophic denitrification bioreactor, which performs autotrophic denitrification of the wastewater. The sulfate-type autotrophic denitrification bioreactor is connected to an ultrafiltration membrane module, which removes organic matter and colloids from the wastewater. The ultrafiltration concentrate outlet of the ultrafiltration membrane module is connected to the sulfate-type autotrophic denitrification bioreactor for secondary autotrophic denitrification of the wastewater, thereby improving the pollutant removal rate. The nanofiltration membrane module is connected to the ultrafiltration membrane module. The nanofiltration membrane has a pore size of 0.5-0.8 nm. The nanofiltration membrane module removes sulfate, ammonia nitrogen, and organic matter from the wastewater. The nanofiltration membrane module is also connected to the influent tank to return the sulfate-rich wastewater to the influent tank, realizing the recycling of sulfate resources. This adapts to the sulfate requirements of the autotrophic denitrification process, eliminating the need for additional sulfate supplementation and reducing operating costs. The effluent tank is connected to the nanofiltration membrane module and stores reclaimed water. Through a three-stage treatment process involving biological reaction, ultrafiltration, and nanofiltration, a closed-loop treatment system is achieved, which includes autotrophic denitrification, pollutant separation, and resource recycling, ensuring that the reclaimed water meets the standards.

[0007] Furthermore, the inlet pool is connected to the inlet end of the sulfate-type autotrophic denitrification bioreactor via a wastewater pipeline, and the wastewater pipeline is equipped with a peristaltic pump. The peristaltic pump has the characteristics of controllable flow and anti-clogging, which can precisely adjust the wastewater inflow to match the treatment load of the sulfate-type autotrophic denitrification bioreactor and avoid microbial activity inhibition caused by water flow fluctuations. The outlet end of the sulfate-type autotrophic denitrification bioreactor is also connected to the inlet end of the ultrafiltration membrane module via a wastewater pipeline. Wastewater pipelines are also installed at the ultrafiltration effluent outlet of the ultrafiltration membrane module and the inlet of the nanofiltration membrane module. A booster pump is installed in this section of the wastewater pipeline to meet the operating pressure requirements of the nanofiltration membrane, ensure that the retention performance of the nanofiltration membrane is fully utilized, avoid the decrease in sulfate and ammonia nitrogen retention rates due to insufficient pressure, and ensure the continuous and stable operation of the entire treatment device.

[0008] Furthermore, the ultrafiltration membrane module's ultrafiltration concentrate outlet is connected to the sulfate-type autotrophic denitrification bioreactor via an ultrafiltration membrane concentrate return pipeline. This avoids pollution caused by direct discharge of pollutants, recovers functional microorganisms, maintains a stable microbial concentration within the sulfate-type autotrophic denitrification bioreactor, and improves denitrification efficiency. The nanofiltration membrane module is connected to the inlet pool via a nanofiltration membrane concentrate return pipeline, enabling directional circulation of sulfate and preventing sulfate loss with the effluent. This also reduces the amount of sulfate replenished in the raw water of the inlet pool, thereby lowering water resource and reagent consumption.

[0009] Furthermore, the sulfate-type autotrophic denitrification bioreactor includes an anaerobic digestion sludge reactor and an anaerobic ammonia oxidation sludge reactor using nitrite as an electron acceptor, achieving zoned and synergistic effects of the two functional sludge components. The anaerobic digestion sludge reactor focuses on sulfate reduction, providing the electron donors required for autotrophic denitrification. The anaerobic ammonia oxidation sludge reactor efficiently degrades ammonia nitrogen; the zoned arrangement of the two components avoids competition among microbial communities and enhances their respective metabolic efficiencies.

[0010] Compared with the prior art, the beneficial effects of this utility model are: (1) In the sulfate-type autotrophic denitrification bioreactor, sulfate-type anaerobic ammonia oxidation and sulfur autotrophic denitrification occur. The sulfur autotrophic denitrification reaction is used to reduce the generated nitrate to nitrogen gas, thereby achieving further denitrification. Wastewater treatment does not require aeration or external carbon source, saving the aeration energy consumption and chemical reagent consumption of conventional sewage treatment.

[0011] (2) Use ultrafiltration membrane to remove organic matter and colloids, providing fine pretreatment for subsequent nanofiltration membrane. Use nanofiltration membrane to concentrate and reflux sulfate in concentrated water, providing reaction conditions for sulfate-type biological denitrification. The effluent from nanofiltration membrane can meet the water quality requirements for regeneration. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a flow chart of the wastewater treatment process of this utility model; Figure 3 This is a schematic diagram illustrating the denitrification effect of this utility model; Figure 4 This is a schematic diagram showing the changes in sulfate concentration in the influent and effluent of this utility model.

[0013] In the diagram: 1. Inlet tank; 2. Sulfate-type autotrophic denitrification bioreactor; 3. Ultrafiltration membrane module; 4. Nanofiltration membrane module; 5. Outlet tank; 6. Peristaltic pump; 7. Booster pump; 8. Wastewater pipeline; 9. Ultrafiltration membrane concentrate return pipeline; 10. Nanofiltration membrane concentrate return pipeline. Detailed Implementation

[0014] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0015] Example: Please see Figure 1-4 This utility model provides a technical solution: An autotrophic denitrification wastewater treatment device includes an inlet tank 1, a nanofiltration membrane module 4, and an outlet tank 5. The inlet tank 1 is used to store and regulate wastewater.

[0016] The inlet tank 1 is connected to the inlet end of the sulfate-type autotrophic denitrification bioreactor 2 by a wastewater pipeline 8, and the wastewater pipeline 8 is equipped with a peristaltic pump 6, which is used to transport wastewater to the sulfate-type autotrophic denitrification bioreactor 2. The sulfate-type autotrophic denitrification bioreactor 2 is used to carry out sulfate-type anaerobic ammonia oxidation and sulfur autotrophic denitrification reactions to achieve autotrophic denitrification.

[0017] Wastewater pipeline 8 is also connected between the effluent end of sulfate-type autotrophic denitrification bioreactor 2 and the influent end of ultrafiltration membrane module 3. Ultrafiltration membrane module 3 is used to remove organic matter and colloids in wastewater, providing fine pretreatment for subsequent nanofiltration membrane module 4. Ultrafiltration concentrate outlet of ultrafiltration membrane module 3 is connected to ultrafiltration concentrate return pipeline 9 between sulfate-type autotrophic denitrification bioreactor 2. Concentrate containing organic matter and colloids is returned to sulfate-type autotrophic denitrification bioreactor 2 for further degradation and autotrophic denitrification by microorganisms.

[0018] Wastewater pipelines 8 are also installed at the ultrafiltration outlet of the ultrafiltration membrane module 3 and the inlet of the nanofiltration membrane module 4. A booster pump 7 is installed in the wastewater pipeline 8. The nanofiltration membrane module 4 is used to intercept sulfate, some ammonia nitrogen and organic matter in the wastewater. A nanofiltration membrane concentrate return pipeline 10 is connected between the nanofiltration membrane module 4 and the inlet pool 1 to send the sulfate-rich wastewater back to the inlet pool 1 to drive the sulfate-type autotrophic denitrification reaction.

[0019] The effluent tank 5 is connected to the nanofiltration membrane module 4. The effluent tank 5 is used to collect nanofiltration effluent that meets the quality requirements for reclaimed water reuse.

[0020] In this embodiment, sulfate-type autotrophic denitrification bioreactor 2 undergoes sulfate-type anaerobic ammonium oxidation and sulfur autotrophic denitrification. The sulfate-type anaerobic ammonium oxidation utilizes sulfate as an electron acceptor to oxidize ammonia nitrogen into nitrogen gas and nitrate. Sulfate is reduced to elemental sulfur or low-valence sulfur elements such as thiosulfate. Further sulfur autotrophic denitrification then reduces the generated nitrate back to nitrogen gas, achieving further denitrification. This process requires no aeration or external carbon source, saving on the aeration energy consumption and chemical reagent consumption of conventional wastewater treatment.

[0021] In this embodiment, the inoculated sludge in the sulfate-type autotrophic denitrification bioreactor 2 is anaerobic digestion sludge and anaerobic ammonia oxidation sludge with nitrite as electron acceptor. The preferred inoculation ratio of the two sludges is 1:1, and the sludge concentration after inoculation is 3-5 g / L.

[0022] In this embodiment, to reduce organic pollution to the nanofiltration membrane module 4, the ultrafiltration membrane module 3 is preferably 10-50 kDa and made of PVDF membrane material. After ultrafiltration membrane separation, the concentrate ratio is about 10%-15%, and the concentrate is returned to the sulfate-type autotrophic denitrification bioreactor 2.

[0023] In this embodiment, the operating pressure of the nanofiltration membrane module 4 is provided by the booster pump 7 to ensure membrane separation efficiency and sulfate rejection rate. The nanofiltration membrane preferably has a pore size of 0.5-0.8 nm and an operating pressure of 0.6-0.8 MPa. The influent SO4 content is... 2- The concentration is approximately 200 mg / L, with a rejection rate of 80%-90%. After removal by the nanofiltration membrane, the concentrate ratio is 15%-25%, and the concentrate contains SO4. 2-The concentration is approximately 600-1200 mg / L, and the concentrated water is returned to the inlet tank 1.

[0024] Specifically, during use, the wastewater to be treated is stored in the inlet tank 1, and then transported directionally to the sulfate-type autotrophic denitrification bioreactor 2 through the wastewater pipeline 8 and peristaltic pump 6. The sulfate-type autotrophic denitrification bioreactor 2 contains anaerobic digestion sludge and anaerobic ammonia oxidation sludge, forming a zoned synergistic system: the sulfate-reducing bacteria in the anaerobic digestion sludge reduce the sulfate in the wastewater, providing electron donors for denitrification; the anaerobic ammonia oxidizing bacteria in the anaerobic ammonia oxidation sludge (using nitrite as an electron acceptor) efficiently convert ammonia nitrogen in the wastewater into nitrogen gas and release it, completing the core denitrification process; Wastewater treated by sulfate-type autotrophic denitrification bioreactor 2 is transported to ultrafiltration membrane module 3 through wastewater pipeline 8. The ultrafiltration membrane retains organic matter, colloids, and suspended functional microorganisms to separate clean water from pollutants and microorganisms. The ultrafiltration effluent enters the subsequent nanofiltration treatment stage, while the ultrafiltration concentrate, which is rich in incompletely degraded pollutants and functional microorganisms, is returned to sulfate-type autotrophic denitrification bioreactor 2 through ultrafiltration membrane concentrate return pipeline 9 for secondary autotrophic denitrification. This not only improves the pollutant removal rate but also maintains a stable microbial concentration within sulfate-type autotrophic denitrification bioreactor 2. After being pressurized by the booster pump 7, the ultrafiltration effluent enters the nanofiltration membrane module 4. Through the precise sieving effect of the nanofiltration membrane, residual sulfate, ammonia nitrogen, and trace organic matter are efficiently intercepted, preventing pollutants from being discharged with the effluent. The intercepted sulfate-rich nanofiltration concentrate is returned to the inlet pool 1 through the nanofiltration membrane concentrate return pipeline 10, realizing the recycling of sulfate resources without the need for additional sulfate replenishment. The qualified reclaimed water produced by the nanofiltration membrane is transported to the outlet pool 5 for storage through a sealed pipeline.

[0025] Autotrophic denitrification utilizes autotrophic microorganisms to carry out biological nitrogen removal reactions, such as anaerobic ammonium oxidation (AMO) with nitrite as the electron acceptor, AMO with sulfate as the electron acceptor, and sulfur autotrophic denitrification with low-valence sulfur as the electron donor. Under the same total nitrogen removal conditions, autotrophic denitrification can reduce aeration energy consumption and save external carbon sources.

[0026] Sulfate-type anaerobic ammonium oxidation is a reaction in which ammonia nitrogen is used as an electron donor to oxidize sulfate. Ammonia nitrogen is oxidized to nitrogen gas and nitrate nitrogen, while sulfate is reduced to lower valence states of sulfur, such as elemental sulfur, sulfites, or thiosulfates. Sulfate autotrophic denitrification is a biological reaction process that uses lower valence sulfur as an electron donor to reduce nitrate and nitrite nitrogen to nitrogen gas. Therefore, sulfur cyclically drives redox reactions of nitrogen at different valence states in both of these reactions.

[0027] Increasing sulfate concentration promotes sulfate-type anaerobic ammonium oxidation. The sulfate concentration in domestic wastewater is typically 20-40 mg / L, limiting this reaction. Adding sulfate to wastewater is not only uneconomical but also leads to increased salinity. Nanofiltration membranes are charged, pressure-driven separation membranes that fall between ultrafiltration and reverse osmosis. Through the synergistic effect of steric hindrance (sieving) and charge effect (Dowson repulsion), they can selectively and efficiently retain divalent and high-valent ions (such as SO42-). 2- It allows some monovalent ions and water molecules to pass through. Based on the sulfate retention effect of nanofiltration membrane, sulfate can be effectively enriched on the concentrate side. At the same time, by utilizing nanofiltration membrane to further retain pollutants, the effluent can meet water quality targets such as regeneration and reuse.

[0028] The wastewater treatment device of this embodiment uses a sulfate-type autotrophic denitrification bioreactor 2 to treat ammonia nitrogen wastewater. The influent ammonia nitrogen concentration in the influent tank 1 is 200 mgN / L and the sulfate concentration is 200 mgS / L. mgN / L represents the mass concentration of nitrogen (N) in ammonia nitrogen only, and mgS / L represents the mass concentration of sulfur (S) in sulfate only.

[0029] The sulfate-type autotrophic denitrification bioreactor 2 was inoculated with anaerobic digestion sludge and anaerobic ammonia oxidation sludge using nitrite as the electron acceptor, at a 1:1 ratio. The sludge concentration after inoculation was 4-5 g / L, and the hydraulic retention time was 2 days. An external carbon source was added throughout the process. The operating temperature of the sulfate-type autotrophic denitrification bioreactor 2 was controlled at 25-30℃, and the pH was controlled at 7.5-8.5. The nitrogen removal efficiency was as follows: Figure 3 As shown, the average ammonia nitrogen concentration in the effluent was 20-30 mg / L, and the denitrification rate was 0.1 kg / (m³). 3 ·d), higher than the conventional nitrogen removal reaction rate of wastewater treatment plants (0.05 kg / (m³). 3 ·d)).

[0030] The sulfate concentrations in the influent and effluent of sulfate-type autotrophic denitrification bioreactor 2 are as follows: Figure 4 As shown. SO4 2- The removal effect of SO4 is not obvious. 2- The average removal rate is approximately 0.005 kg / (m³). 3 ·d), SO3 was detected in the water at the same time. 2- Concentration below 1 mg / L, S 2- The concentration is on the order of μg / L. A relatively small amount of SO4. 2- The concentration change indicates that sulfate underwent a reduction and oxidation cycle in this reaction unit.

[0031] The effluent from sulfate-type autotrophic denitrification bioreactor 2 enters ultrafiltration membrane module 3 for pretreatment to remove organic matter and colloids, and then enters nanofiltration membrane module 4 for further removal of sulfate, residual ammonia nitrogen, and COD. The final effluent indicators are as follows: The ultrafiltration membrane module 3 is used for the advanced treatment of the effluent from the sulfate-type autotrophic denitrification bioreactor 2. The ultrafiltration membrane effluent has a COD ≤ 20 mg / L, turbidity ≤ 1 NTU, and colloid removal rate ≥ 90%.

[0032] The nanofiltration membrane has a pore size of 0.6 nm, an operating pressure of 0.7 MPa, an actual sulfate rejection rate of 85%, a concentrate ratio of 20%, and a concentrate SO4 content of [missing information]. 2- Concentration 800 mg / L.

[0033] The effluent from the nanofiltration membrane has ammonia nitrogen ≤5mg / L, COD ≤10mg / L, and sulfate ≤50mg / L, which meets the standard of GB / T18920-2022 "Water Quality Standard for Urban Wastewater Reuse for Miscellaneous Uses".

[0034] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An autotrophic denitrification wastewater treatment device, characterized in that, include: The wastewater in the inlet pool flows into a sulfate-type autotrophic denitrification bioreactor for autotrophic denitrification. The wastewater in the sulfate-type autotrophic denitrification bioreactor flows into an ultrafiltration membrane module to remove organic matter and colloids from the wastewater. The ultrafiltration concentrate outlet of the ultrafiltration membrane module is connected to the sulfate-type autotrophic denitrification bioreactor for secondary autotrophic denitrification of the wastewater. A nanofiltration membrane module, which is connected to an ultrafiltration membrane module to collect wastewater, wherein the sulfate-rich wastewater in the nanofiltration membrane module is returned to the influent tank; An effluent tank stores regenerated water filtered by the nanofiltration membrane module.

2. The autotrophic denitrification wastewater treatment device according to claim 1, characterized in that: The inlet pool is connected to the inlet end of the sulfate-type autotrophic denitrification bioreactor by a wastewater pipeline, and a peristaltic pump is installed on the wastewater pipeline. The outlet end of the sulfate-type autotrophic denitrification bioreactor is also connected to the inlet end of the ultrafiltration membrane module by a wastewater pipeline.

3. The autotrophic denitrification wastewater treatment device according to claim 2, characterized in that: Wastewater pipelines are also installed at the ultrafiltration outlet of the ultrafiltration membrane module and the inlet of the nanofiltration membrane module, and booster pumps are installed in the wastewater pipelines.

4. The autotrophic denitrification wastewater treatment device according to claim 1, characterized in that: The ultrafiltration membrane module has an ultrafiltration concentrate outlet connected to the sulfate-type autotrophic denitrification bioreactor via an ultrafiltration membrane concentrate return pipeline, and the nanofiltration membrane module has a nanofiltration membrane concentrate return pipeline connected to the inlet tank.

5. The autotrophic denitrification wastewater treatment device according to claim 1, characterized in that: The sulfate-type autotrophic denitrification bioreactor includes an anaerobic digestion sludge reaction component and an anaerobic ammonia oxidation sludge reaction component that uses nitrite as an electron acceptor.

6. The autotrophic denitrification wastewater treatment device according to claim 1, characterized in that: The nanofiltration membrane of the nanofiltration membrane module has a pore size of 0.5-0.8 nm.

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