Denitration sewage treatment device

Abstract

The invention provides a denitration sewage treatment device and device, and relates to the technical field of sewage treatment.The device is characterized in that on the basis of the traditional process that an anaerobic tank, an anoxic tank and an aerobic tank are connected in series, a denitration tank is additionally arranged at the front end of the anaerobic tank, and the front section of the denitration tank is an independent partitioned mixing tank provided with a sludge stirrer; according to the method disclosed by the invention, external sewage and refluxed activated sludge are introduced into the mixing tank together to be quickly mixed, then dissolved oxygen carried by the refluxed sludge is consumed by using organic matters in the sewage as a carbon source in the denitration area, and the sewage enters a subsequent anaerobic tank after pre-denitration treatment is completed. Through the pretreatment step, the inhibition effect of dissolved oxygen in the returned sludge on subsequent anaerobic and anoxic units is effectively eliminated, the operation contradiction between nitrification and denitrification in the traditional A2O process is solved, and the nitrogen and phosphorus removal efficiency and the operation stability of the whole system are remarkably improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and in particular relates to a denitrification sewage treatment device. Background Art

[0002] In the wastewater treatment sector, the anaerobic-anoxic-aerobic (A2O) process has been widely used due to its ability to simultaneously achieve biological denitrification and biological phosphorus removal. This process primarily consists of three core reaction zones: anaerobic, anoxic, and aerobic tanks. In the aerobic tank, ammonia nitrogen is nitrified to nitrate by aerobic microorganisms, providing the prerequisite for denitrification. Simultaneously, phosphate-accumulating bacteria (PABs) absorb excess P during this stage, achieving P removal.

[0003] However, the A2O process has an inherent technical bottleneck: to ensure efficient nitrification, the aerobic tank must maintain a high dissolved oxygen concentration. When the mixed liquor at the end of the aerobic tank and the activated sludge concentrated in the sedimentation tank flow back to the front of the system, the high concentration of dissolved oxygen they carry with them directly enters the anaerobic and anoxic zones. This dissolved oxygen severely damages the anaerobic environment in the anaerobic zone, inhibiting the phosphorus release process of phosphate-accumulating bacteria; it also interferes with the anoxic environment in the anoxic zone, reducing the denitrification efficiency of denitrifying bacteria. This conflict between nitrification and denitrification, and between phosphorus release and absorption, caused by the circulation and interference of dissolved oxygen between different treatment units, limits further improvements in the treatment efficiency and stability of the traditional A2O process. Summary of the Invention

[0004] In order to overcome the problems in the background technology, the present invention provides a denitrification wastewater treatment device and method that can eliminate the adverse effects of dissolved oxygen in return sludge on the front end of the system, so as to improve the overall denitrification and phosphorus removal efficiency.

[0005] To achieve the above object, the present invention is implemented through the following technical solutions: A denitrification sewage treatment device comprises a denitrification tank, a sludge agitator, and a submersible agitator. The front section of the denitrification tank is a mixing tank with an independent partition. The mixing tank is provided with a first inlet connected to an external sewage inlet pipeline, and a second inlet connected to a sludge return pipeline of an aerobic tank. The sludge agitator is installed in the mixing tank. The power input end of the sludge agitator is connected to the power output end of a motor installed outside the mixing tank. An overflow is provided in the mixing tank to connect to the denitrification zone of the denitrification tank. The rear section of the denitrification zone is provided with a water outlet connected to an anaerobic tank. The submersible agitator is installed in the denitrification zone.

[0006] Furthermore, the hydraulic retention time corresponding to the effective volume of the denitrification zone of the denitrification tank is not less than the hydraulic retention time of the anaerobic tank.

[0007] Furthermore, the water inlet and outlet of the denitrification zone of the denitrification pool adopt a structure of entering from the top and exiting from the bottom, and facing each other on two opposite sides of the denitrification zone.

[0008] A denitrification wastewater treatment process, applied to the denitrification wastewater treatment device, comprises the following steps: S1, pre-denitrification and mixing The external sewage is introduced into the mixing tank through the first inlet, and the return sludge generated in the subsequent aerobic treatment step is introduced into the mixing tank through the second inlet. The sludge agitator is started to perform rapid shear mixing on the two water streams, and the fully mixed liquid enters the denitrification zone through the overflow port; In the denitrification zone, the submersible agitator is started to perform gentle and continuous stirring to meet the reaction residence time requirements. The organic matter in the sewage is used as a carbon source, allowing microorganisms to consume the dissolved oxygen carried by the return sludge, thus completing the pre-denitrification treatment. S2. Anaerobic treatment The mixed liquid that has undergone the pre-denitrification treatment in step S is drawn out from the outlet of the denitrification zone and sent to the subsequent anaerobic tank for anaerobic treatment to create an excellent phosphorus release environment; S3. Hypoxia treatment The mixed liquid after anaerobic treatment is sent to the anoxic tank and mixed with the nitrified liquid returned from the aerobic tank in the subsequent step S, and denitrification treatment is carried out under anoxic conditions; S4. Aerobic treatment The mixed liquid after anoxic treatment is sent to the aerobic pool to efficiently degrade organic matter, complete the nitrification of ammonia nitrogen, and achieve excessive phosphorus absorption by polyphosphate bacteria; S5. Reflux loop construction The mixed liquor after treatment in the aerobic tank is sent to the sedimentation tank for solid-liquid separation, and the supernatant is discharged as qualified effluent; a portion of the activated sludge at the bottom of the sedimentation tank is used as return sludge and returned to the second inlet of the mixing tank in step S through the sludge return pipeline; at the same time, a portion of the mixed liquor at the end of the aerobic tank is returned to the anoxic tank in step S as nitrification liquid.

[0009] Beneficial effects of the present invention: 1. The newly added pre-denitrification tank consumes the dissolved oxygen that is harmful to subsequent processes in advance, achieving efficient coordinated operation of aerobic nitrification and anoxic denitrification; 2. The total nitrogen removal rate is improved, while the phosphorus release environment in the anaerobic zone is guaranteed, and the overall nitrogen and phosphorus removal efficiency and stability of the system are greatly enhanced; 3. The organic matter in the influent is used as the carbon source for the deoxygenation process, achieving waste treatment with waste. No additional chemicals are required, and the operating cost is low. The submersible agitator not only performs the basic function of preventing sedimentation, but also increases oxygen consumption, thereby improving the overall efficiency of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of the overall structure of this application; Figure 2 This is a schematic diagram of the internal structure of this application Figure 1 ; Figure 3 This is a schematic diagram of the internal structure of this application Figure 2 ; Figure 4 This is a schematic diagram of the internal structure of this application Figure 3 ; Figure 5 This is a schematic diagram of the denitrification wastewater treatment process flow for this application.

[0011] 001-denitrification tank, 011-mixing tank, 111-first inlet, 112-second inlet, 113-overflow, 012-denitrification area, 121-water outlet, 002-sludge agitator, 003-submersible agitator, 004-motor. DETAILED DESCRIPTION

[0012] In order to make the objectives, technical solutions and beneficial effects of the present invention clearer, preferred embodiments of the present invention will be described in detail below to facilitate understanding by technicians.

[0013] The present invention discloses a denitrification sewage treatment device, which improves the traditional A2O process. Figure 1 and Figure 2 As shown, the denitrification tank 001 consists of two independent partitions: a mixing tank 011 at the front and a denitrification zone 012 at the rear. External sewage enters the mixing tank 011 through a first inlet 111, and the return activated sludge from the secondary sedimentation tank at the rear end of the system also enters the mixing tank 011 through a second inlet 112. like Figure 2 and Figure 3 As shown, a sludge agitator 002 is installed in the mixing tank 011, which is powered by an external motor 004. The function of the agitator is to quickly and highly shear mix the two liquids with different properties that have just entered, ensuring that the sludge, sewage and dissolved oxygen are quickly evenly distributed at the microscopic level.

[0014] like Figure 3 and Figure 4 As shown, the fully mixed liquid flows smoothly into the main denitrification zone 012 through the overflow port 113 (such as a weir or baffle). The hydraulic retention time of the denitrification zone 012 is designed to be the same as that of the subsequent anaerobic tank, which is 1-2 hours. To prevent sludge from settling during this period and maintain a gentle, full-area stirring state, a submersible agitator 003 is installed in the denitrification zone 012. Microorganisms use the organic matter in the sewage to consume the dissolved oxygen carried by the return sludge as electron acceptors until it is exhausted. This process is called pre-denitrification treatment. After the pre-denitrification treatment, the mixed liquid with extremely low dissolved oxygen content enters the subsequent anaerobic tank through the outlet 121 located at the rear section of the denitrification zone 012.

[0015] In this embodiment, the overflow port 113 is located on the upper side of the denitrification zone, while the water outlet 121 is located on the lower opposite side of the denitrification zone, forming a flow path that enters from the top and exits from the bottom and runs opposite to each other, which can effectively avoid short-circuiting.

[0016] like Figure 5 As shown, the steps of the denitrification wastewater treatment process of the denitrification wastewater treatment device of the present invention are: S1, pre-denitrification and mixing Rapid physical mixing: External sewage rich in organic matter (BOD / COD) is introduced into the mixing tank 011 at the front end of the system through the first inlet 111. At the same time, the return activated sludge from the sedimentation tank at the end of the system, which is rich in microorganisms but has a high dissolved oxygen concentration, is also sent to the same mixing tank 011 through the second inlet 112. The two streams enter and the sludge agitator 002 installed in the mixing tank 011 is started. The agitator is a high-shear mechanical stirring device. Its function is to break up and mix the two streams in an extremely small volume and an extremely short residence time, preferably 1-5 minutes, to achieve a uniform distribution among the organic matter in the sewage, the microorganisms in the sludge, and the dissolved oxygen, thereby ensuring the start of subsequent biochemical reactions and consuming the dissolved oxygen under the same hydraulic retention time as the anaerobic tank. After rapid mixing, the liquid flows smoothly into the main denitrification zone 012 through the overflow port 113. The denitrification zone 012 can provide a reaction time equivalent to the hydraulic retention time of the anaerobic tank (1-2 hours). In this zone, the submersible agitator 003 performs gentle and continuous stirring. Its purpose is to prevent the activated sludge from settling and keep it in a suspended state; secondly, it drives the liquid in the entire zone to flow slowly, ensuring that all mixed liquids undergo sufficient and uniform reactions: microorganisms consume dissolved oxygen through aerobic respiration, transforming the zone into an anoxic environment with extremely low dissolved oxygen concentration (less than 0.2 mg / L). If the return sludge still carries a small amount of nitrate, then after the dissolved oxygen is exhausted, denitrifying bacteria will use the nitrate for denitrification, further reducing the total nitrogen. The final product of this step is a mixed liquor in which dissolved oxygen is completely removed, total nitrogen is reduced to a certain extent, and organic matter is partially consumed. This mixed liquor creates the most ideal inlet conditions for the subsequent anaerobic treatment steps.

[0017] S2. Anaerobic treatment The mixed liquid pretreated in step S1 enters the anaerobic tank from the outlet 121 of the denitrification zone 012. Since the dissolved oxygen and nitrate in the influent have been removed in advance, a strict anaerobic environment can be maintained in the anaerobic tank. Under this environment, polyphosphate bacteria will undergo an anaerobic phosphorus release process. They decompose the polyphosphates stored in their bodies to obtain energy, thereby releasing a large amount of phosphate into the water body, increasing the phosphorus concentration in the water body.

[0018] S3. Hypoxia treatment The mixed liquid after anaerobic treatment is sent to the anoxic tank. At the same time, the nitrate-rich mixed liquid from the end of the aerobic tank in step S4 (i.e., the nitrified liquid refluxed internally) is also pumped here. The two liquids are mixed in the anoxic tank. Denitrifying bacteria use the remaining organic matter as a carbon source to reduce the nitrate in the nitrified liquid to harmless nitrogen (N2). The nitrogen escapes from the water, thereby achieving the removal of total nitrogen.

[0019] S4. Aerobic treatment The mixed liquid after the anoxic treatment is sent to the aerobic tank, and a large amount of oxygen is supplied to the tank through aeration and other methods to maintain a high dissolved oxygen state. During this stage, three important biochemical processes mainly occur: aerobic microorganisms decompose most of the remaining organic matter into carbon dioxide and water; nitrifying bacteria oxidize ammonia nitrogen in the water into nitrate nitrogen, providing denitrification raw materials for step S3; in an aerobic environment, polyphosphate bacteria absorb phosphorus, thereby greatly reducing the phosphorus content in the effluent.

[0020] S5. Reflux loop construction The mixed liquor after treatment in the aerobic tank enters the sedimentation tank, and the activated sludge settles to the bottom of the tank due to gravity and is separated from the clean water on the upper layer. The supernatant is the final treated effluent that meets the standards and can be discharged; part of the concentrated activated sludge at the bottom of the sedimentation tank is pumped back to the starting point of the entire process, that is, the mixing tank 011 in step S1, through the sludge return pipeline; at the same time, a part of the nitrate-rich mixed liquor at the end of the aerobic tank S4 is pumped to the front end of the anoxic tank S3 through the internal return pipeline to provide the necessary nitrate for denitrification.

[0021] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A denitrification wastewater treatment device, characterized in that: The invention comprises a denitrification tank (001), a sludge agitator (002), and a submersible agitator (003). The front section of the denitrification tank (001) is a mixing tank (011) with independent partitions. The mixing tank (011) is provided with a first inlet (111) connected to an external sewage inlet pipeline. The mixing tank (011) is provided with a second inlet (112) connected to a sludge return pipeline of an aerobic tank. The sludge agitator (002) is installed in the mixing tank (011). The power input end of the sludge agitator (002) is connected to the power output end of a motor (004) installed outside the mixing tank (011). The mixing tank (011) is provided with an overflow port (113) connected to a denitrification zone (012) of the denitrification tank (001). The rear section of the denitrification zone (012) is provided with a water outlet (121) connected to an anaerobic tank. The submersible agitator (003) is installed in the denitrification zone (012).

2. The denitrification wastewater treatment device according to claim 1, characterized in that: The hydraulic retention time corresponding to the effective volume of the denitrification zone (012) of the denitrification tank (1) is not less than the hydraulic retention time of the anaerobic tank.

3. The denitrification wastewater treatment device according to claim 1, characterized in that: The water inlet and outlet of the denitrification zone (012) of the denitrification pool (1) adopt a structure of upper inlet and lower outlet, and are arranged opposite to each other on two opposite sides of the denitrification zone (012).

4. A denitrification wastewater treatment process, applied to the denitrification wastewater treatment device according to any one of claims 1 to 3, characterized in that: The steps include: S1, pre-denitrification and mixing The external sewage is introduced into the mixing tank (011) through the first inlet (111), and the return sludge generated in the subsequent aerobic treatment step is introduced into the mixing tank (011) through the second inlet (112), and the sludge agitator (002) is started to perform rapid shear mixing on the two water streams, so that the fully mixed liquid enters the denitrification zone (012) through the overflow port (113); In the denitrification zone (012), the submersible agitator (003) is started to perform gentle and continuous stirring to meet the reaction residence time requirement, and the organic matter in the sewage is used as a carbon source to enable microorganisms to consume the dissolved oxygen carried in the return sludge, thereby completing the pre-denitrification treatment; S2. Anaerobic treatment The mixed liquid that has undergone the pre-denitrification treatment in step S1 is drawn out from the outlet (121) of the denitrification zone (012) and sent to a subsequent anaerobic tank for anaerobic treatment to create an excellent phosphorus release environment; S3. Hypoxia treatment The anaerobic mixed liquid is sent to the anoxic tank and mixed with the nitrified liquid returned from the aerobic tank in the subsequent step S4, and denitrification treatment is carried out under anoxic conditions; S4. Aerobic treatment The mixed liquid after anoxic treatment is sent to the aerobic pool to efficiently degrade organic matter, complete the nitrification of ammonia nitrogen, and achieve excessive phosphorus absorption by polyphosphate bacteria; S5. Reflux loop construction The mixed liquor after treatment in the aerobic tank is sent to the sedimentation tank for solid-liquid separation, and the supernatant is discharged as qualified effluent; a portion of the activated sludge at the bottom of the sedimentation tank is used as return sludge and returned to the second inlet (112) of the mixing tank (011) of step S1 through the sludge return pipeline; at the same time, a portion of the mixed liquor at the end of the aerobic tank is returned to the anoxic tank of step S3 as nitrification liquid.

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